[Federal Register Volume 90, Number 186 (Monday, September 29, 2025)]
[Rules and Regulations]
[Pages 46483-46509]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2025-18816]
[[Page 46483]]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 131
[EPA-HQ-OW-2023-0222; FRL 10760-02-OW]
RIN 2040-AG30
Water Quality Standards To Protect Aquatic Life in the Delaware
River
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.
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SUMMARY: The U.S. Environmental Protection Agency (EPA) is finalizing
revised water quality standards (WQS) largely as proposed for certain
water quality management zones of the mainstem Delaware River under the
Clean Water Act (CWA). Specifically, the EPA is promulgating a
designated use of protection and propagation of resident and migratory
aquatic life and corresponding dissolved oxygen water quality criteria
for the mainstem Delaware River in Zone 3, Zone 4, and the upper
portion of Zone 5 (in total, river miles 108.4 to 70.0).
DATES: This final rule is effective on November 28, 2025.
ADDRESSES: The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OW-2023-0222. All documents in the docket are
listed on the https://www.regulations.gov website. Although listed in
the index, some information is not publicly available, e.g.,
Confidential Business Information or other information whose disclosure
is restricted by statute. Certain other material, such as copyrighted
material, is not placed on the internet and will be publicly available
only in hard copy form. Publicly available docket materials are
available electronically through https://www.regulations.gov.
FOR FURTHER INFORMATION CONTACT: Hannah Lesch, Office of Water,
Standards and Health Protection Division (4305T), Environmental
Protection Agency, 1200 Pennsylvania Avenue NW, Washington, DC 20460;
telephone number: (202) 566-1224; email address: [email protected].
SUPPLEMENTARY INFORMATION: The information in this preamble is
organized as follows:
I. General Information
A. Does this action apply to me?
B. How did the EPA develop this final rule?
II. Background
A. Statutory and Regulatory Authority
B. Relevant Ecological History of the Delaware River
C. Administration of Water Quality Standards in the Delaware
River
D. Relevant Aquatic Life Designated Uses and Dissolved Oxygen
Criteria Prior to Promulgation of This Final Rule
E. Summary of the EPA Administrator's Determination
III. Final Water Quality Standards
A. Scope of the EPA's Rule
B. Aquatic Life Designated Use
C. Dissolved Oxygen Criteria To Protect Aquatic Life Propagation
IV. Endangered Species Act Consultation
V. Applicability
VI. Conditions Under Which Federal Water Quality Standards Would Be
Withdrawn
VII. Alternative Regulatory Approaches and Implementation Mechanisms
A. Water Quality Standards Variances and NPDES Permit Compliance
Schedules
B. Clean Water Act Section 303(d)/305(b) Water Quality
Assessments
VIII. Economic Analysis
A. Baseline for the Analysis
B. Development of the Policy Scenario
C. Potential Costs
D. Potential Benefits
E. Conclusion
IX. Statutory and Executive Order Reviews
A. Executive Order 12866: Regulatory Planning and Review and
Executive Order 13563: Improving Regulation and Regulatory Review
B. Executive Order 14192: Unleashing Prosperity Through
Deregulation
C. Paperwork Reduction Act (PRA)
D. Regulatory Flexibility Act (RFA)
E. Unfunded Mandates Reform Act (UMRA)
F. Executive Order 13132: Federalism
G. Executive Order 13175: Consultation and Coordination With
Indian Tribal Governments
H. Executive Order 13045: Protection of Children From
Environmental Health Risks and Safety Risks
I. Executive Order 13211: Actions That Significantly Affect
Energy Supply, Distribution, or Use
J. National Technology Transfer and Advancement Act (NTTAA)
K. Congressional Review Act (CRA)
I. General Information
A. Does this action apply to me?
Table 1 of this preamble identifies a range of individuals and
entities that could be indirectly affected by this final rule. For
example, entities that discharge pollutants to certain waters under the
jurisdiction of the States of Delaware, New Jersey, and Pennsylvania--
such as industrial facilities and municipalities that manage
stormwater, separate sanitary, or combined sewer systems--could be
indirectly affected by this rule because the Federal WQS promulgated by
the EPA in this rule are applicable WQS for these waters for CWA
purposes. Specifically, these Federal WQS are the applicable standards
that must be used in CWA regulatory programs, such as permitting under
the National Pollutant Discharge Elimination System (NPDES) under CWA
section 402 \1\ and identifying impaired waters under CWA section
303(d). In addition, individuals and entities who rely on or benefit
from aquatic life in these waters may be indirectly affected.
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\1\ Before any water quality-based effluent limit could be
included in an NPDES permit, the permitting authority (here, the
states of Delaware, New Jersey, and Pennsylvania), must first
determine whether a discharge ``will cause or has the reasonable
potential to cause, or contribute to an excursion above any WQS.''
40 CFR 122.44(d)(1)(i) and (ii).
Table 1--Entities Potentially Indirectly Affected by This Rule
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Examples of potentially indirectly
Category affected entities
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Industry..................... Industrial point sources discharging to
certain waters in Delaware, New Jersey,
and Pennsylvania. Commercial fishing
operations that harvest fish.
Municipalities, including Publicly owned treatment works or similar
those with stormwater or facilities responsible for managing
combined sewer system stormwater, separate sanitary, or
outfalls. combined sewer systems that discharge to
certain waters in Delaware, New Jersey,
and Pennsylvania.
Recreation and Tourism....... Anglers and tourists seeking recreational
opportunities related to aquatic life in
certain waters in Delaware, New Jersey,
and Pennsylvania.
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This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities that could be indirectly affected
by this action. If you have questions regarding the applicability of
this action to a particular entity, consult the person listed in the
FOR FURTHER INFORMATION CONTACT section above.
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B. How did the EPA develop this final rule?
In developing this final rule, the EPA carefully considered the
public comments and input received from interested parties. The EPA
provided a 60-day public comment period after publishing the proposed
rulemaking in the Federal Register on December 21, 2023.\2\ In
addition, the EPA held two online public hearings on February 6 and 7,
2024, to discuss the contents of the proposed rulemaking and accept
verbal public comments.
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\2\ United States Environmental Protection Agency. Proposed
Rule: Water Quality Standards to Protect Aquatic Life in the
Delaware River. 88 FR 88315, December 21, 2023.
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The EPA received approximately 4,800 total comments on a range of
issues. Most commenters were supportive of the EPA's proposal to revise
WQS in the Delaware River. Some commenters expressed concerns regarding
potential implementation costs and the potential cost to water utility
ratepayers. Other commenters focused on aspects of the methods the EPA
used to derive the dissolved oxygen criteria and the stringency of the
proposed criteria. In this preamble, the EPA explains how it responded
to certain comments received on aspects of the proposal. A complete
record of the comments received and the EPA's responses is available in
the associated response to comments document in the official public
docket.\3\
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\3\ A complete record of the comments received and the EPA's
responses is available in the associated Response to Comments
document in the official public docket (regulations.gov, docket ID
EPA-HQ-OW-2023-0222).
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II. Background
A. Statutory and Regulatory Authority
CWA section 101(a)(2) establishes a national goal of ``water
quality which provides for the protection and propagation of fish,
shellfish, and wildlife and provides for recreation in and on the
water'' (hereafter, collectively referred to as ``101(a)(2) uses'' or
``101(a)(2) goals''), wherever attainable.\4\ CWA section 303(c)(2)(A)
provides that WQS must protect the public health or welfare, enhance
water quality, and serve the purposes of the CWA, taking into
consideration the use and value of water for the propagation of fish
and wildlife.\5\ The EPA's regulation at 40 CFR 131.10 implements these
statutory provisions.
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\4\ 33 U.S.C. 1251(a)(2); see also 40 CFR 131.2.
\5\ 33 U.S.C. 1313(c)(2)(A).
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Under CWA section 303(c), states \6\ have the primary
responsibility for reviewing, establishing, and revising WQS applicable
to their waters. In CWA section 303(c)(4), Congress directs the EPA to
promulgate Federal WQS in two situations. First, if the EPA determines
that a state's new or revised WQS are not consistent with the
requirements of the CWA and specifies changes to meet such
requirements, the state has 90 days to submit a modified standard to
the EPA. If the state fails to submit new or revised WQS that meet the
CWA's requirements, then the EPA must propose and promulgate new or
revised Federal WQS for the waters involved.\7\ Second, the EPA
Administrator has the authority to propose and promulgate standards in
any case where the Administrator determines that a new or revised
standard is necessary to meet the requirements of the CWA.\8\ The EPA
refers to a determination pursuant to CWA section 303(c)(4)(B) as an
``Administrator's Determination.'' \9\ In either instance, CWA section
303(c)(4) states that the EPA must promulgate new or revised WQS,
``unless prior to such promulgation,'' a state adopts and EPA approves
new or revised WQS that meet the CWA's requirements.
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\6\ Pursuant to 40 CFR 131.3(j), ``states'' also includes
territories and ``Indian Tribes that EPA determines to be eligible
for purposes of the water quality standards program.''
\7\ CWA section 303(c)(4)(A).
\8\ CWA section 303(c)(4)(B).
\9\ CWA section 303(c)(4)(B); 40 CFR 131.22(b).
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WQS define the desired condition of a water body by designating the
use or uses to be made of the water \10\ and by setting water quality
criteria to protect those uses.\11\ There are two primary categories of
water quality criteria: human health criteria and aquatic life
criteria. Human health criteria protect designated uses such as public
water supply, recreation, and fish and shellfish consumption. Aquatic
life criteria protect designated uses such as survival, growth, and
reproduction of fish, invertebrates, and other aquatic species. The
EPA's regulation provides that water quality criteria ``must be based
on sound scientific rationale and must contain sufficient parameters or
constituents to protect the designated use. For waters with multiple
use designations, the criteria shall support the most sensitive use.''
\12\
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\10\ 40 CFR 131.2 and 131.10.
\11\ 40 CFR 131.2 and 131.11.
\12\ 40 CFR 131.11(a)(1).
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States are required to hold a public hearing to review applicable
WQS at least once every three years and, if appropriate, revise or
adopt new standards, including additional attainable designated
uses.\13\ Any new or revised WQS must be submitted to the EPA for
review and approval or disapproval.\14\ As explained above, CWA section
303(c)(4)(B) independently authorizes the Administrator to determine
that a new or revised standard is necessary to meet CWA requirements.
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\13\ CWA section 303(c)(1); 40 CFR 131.20(a).
\14\ CWA section 303(c)(2)(A) and (c)(3).
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B. Relevant Ecological History of the Delaware River
The Delaware River has historically been home to numerous species
of ecological, recreational, and economic importance. However, water
quality impacts and habitat degradation, peaking in the mid-twentieth
century, made portions of the river unsuitable for many aquatic
species--such as the Atlantic Sturgeon (Acipenser oxyrinchus
oxyrinchus), Shortnose Sturgeon (A. brevirostrum), American Shad (Alosa
sapidissima), and Striped Bass (Morone saxatilis), among others \15\--
that are sensitive to seasonal anoxia (i.e., absence of sufficient
oxygen) in the mainstem Delaware River in Zone 3, Zone 4, and the upper
portion of Zone 5 (in total, river miles 108.4 to 70.0; hereafter,
referred to as ``specified zones'' or ``relevant
zones'').16 17
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\15\ Stoklosa, A.M., Keller, D.H., Marano, R., and Horwitz, R.J.
(2018). ``A Review of Dissolved Oxygen Requirements for Key
Sensitive Species in the Delaware Estuary.'' Academy of Natural
Sciences of Drexel University. November 2018. https://www.nj.gov/drbc/library/documents/Review_DOreq_KeySensSpecies_DelEstuary_ANStoDRBCnov2018.pdf.
\16\ Hardy, C.A. (1999). Fish or Foul: A History of the Delaware
River Basin Through the Perspective of the American Shad, 1682 to
the Present. Pennsylvania History, 66(4), 506-534. https://digitalcommons.wcupa.edu/hist_facpub/13;
Secor, D.H. and Waldman, J. (1999). Historical abundance of
Delaware Bay Atlantic sturgeon and potential rate of recovery.
American Fisheries Society Symposium. 23. 203-216. https://www.researchgate.net/publication/291783957_Historical_abundance_of_Delaware_Bay_Atlantic_sturgeon_and_potential_rate_of_recovery;
Smith, T.I.J., & Clugston, J.P. (1997) Status and management of
Atlantic sturgeon, Acipenser oxyrinchus, in North America.
Environmental Biology of Fishes 48, 335-346. https://doi.org/10.1023/A:1007307507468;
National Marine Fisheries Service. (1998). Recovery Plan for the
Shortnose Sturgeon (Acipenser brevirostrum). Prepared by the
Shortnose Sturgeon Recovery Team for the National Marine Fisheries
Service, Silver Spring, Maryland. 104 pages. https://repository.library.noaa.gov/view/noaa/15971;
Atlantic States Marine Fisheries Commission. (1981). Interstate
Fisheries Management Plan for the Striped Bass. http://www.asmfc.org/uploads/file/1981FMP.pdf.
\17\ A map showing the Delaware River watershed and the
specified zones is available in the docket (Docket ID No. EPA-HQ-OW-
2023-0222) as well as in each of the supporting documents associated
with this final rule: Technical Support Document for the Final Rule:
Water Quality Standards to Protect Aquatic Life in the Delaware
River; and Economic Analysis for the Final Rule: Water Quality
Standards to Protect Aquatic Life in the Delaware River.
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Dissolved oxygen is an important water quality parameter that can
significantly influence the distribution and abundance of aquatic
organisms and their ecological relationships in aquatic ecosystems.
Aquatic organisms need adequate levels of dissolved oxygen to maintain
and support normal functions, especially during the sensitive early
life history when spawning, larval development, and juvenile growth
occur.\18\ As dissolved oxygen levels decrease in a waterbody, the rate
at which aquatic organisms can obtain oxygen from the water decreases,
resulting in impaired growth and reduced survival. Maintaining a
healthy ecosystem requires dissolved oxygen at levels that do not
impair growth and survival of aquatic species.
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\18\ United States Environmental Protection Agency. (2021).
Factsheet on Water Quality Parameters: Dissolved Oxygen. July 2021.
Document ID: EPA 841F21007B. https://www.epa.gov/system/files/documents/2021-07/parameter-factsheet_do.pdf;
United States Environmental Protection Agency. (2023a).
Indicators: Dissolved Oxygen. June 9, 2023. https://www.epa.gov/national-aquatic-resource-surveys/indicators-dissolved-oxygen.
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1. Causes of Low Dissolved Oxygen in the Specified Zones of the
Delaware River
Discharges of untreated or poorly treated municipal and industrial
wastewater into the Delaware River have historically been a major cause
of water quality degradation, including oxygen depletion, in the
specified zones.\19\ While conditions have significantly improved,
inputs of oxygen-consuming wastes from wastewater dischargers,
especially ammonia (NH3) and ammonium (NH4\+\)
(which in combination are hereafter referred to as ``ammonia
nitrogen''), as well as sediment-water ammonium flux and sediment
oxygen demand, continue to be significant sources of oxygen demand in
the specified zones of the Delaware River.\20\
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\19\ Hardy (1999); Delaware River Basin Commission. (2024a). A
Pathway for Continued Restoration: Improving Dissolved Oxygen in the
Delaware River Estuary. Technical Report No. 2024-6. September 2024.
https://www.nj.gov/drbc/library/documents/ALDU_RestorationPathway/Report_RestorationPathway_sept2024.pdf.
\20\ Delaware River Basin Commission (2024a); Delaware River
Basin Commission. (2024b). Modeling Eutrophication Processes in the
Delaware River Estuary: Three-Dimensional Water Quality Model.
Technical Report No. 2024-5. August 2024. https://www.nj.gov/drbc/library/documents/ALDU_RestorationPathway/WQCalibration_FinalRpt_aug2024.pdf.
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Along the Delaware River, untreated wastewater discharges typically
occur during and after rainfall events due to combined sewer overflows
(CSOs), which are a source of nutrients (i.e., nitrogen and
phosphorus), sediments, and toxic contaminants, and can lead to
increased chemical and biological oxygen demand in the river.\21\
Although the cumulative impact of historical CSOs on sediment oxygen
demand in the Delaware River has not been estimated, over time, CSOs
can increase or maintain sediment oxygen demand as untreated organic
material settles on the riverbed and is broken down by oxygen consuming
bacteria (thus, removing oxygen from the water column), a process that
continues long after the end of an overflow event.\22\ CSOs have been a
persistent source of pollutants in the specified zones of the Delaware
River for over a century. For example, sewer overflows from
Philadelphia in the early 1900s deposited over 200,000 tons of solids
per year, which, in combination with other solid wastes, created
deposits 12 feet deep in the river.\23\ From July 1, 2022 to June 30,
2023, Philadelphia's wastewater system alone discharged over 1.35
billion cubic feet of CSOs into the Delaware River and its
tributaries.\24\
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\21\ Miskewitz, R. and Uchrin, C. (2013). In-Stream Dissolved
Oxygen Impacts and Sediment Oxygen Demand Resulting from Combined
Sewer Overflow Discharges. Journal of Environmental Engineering,
139(10). https://doi.org/10.1061/(ASCE)EE.1943-7870.0000739.
\22\ Miskewitz and Uchrin (2013).
\23\ Hardy (1999).
\24\ Philadelphia Water Department. (2023). Combined Sewer
Management Program Annual Report. Stormwater Management Program
Annual Report. See Appendix D--``NPDES Annual CSO Status Report FY
2023,'' Table 2--``Overflow Summary for 7/1/2022-6/30/2023.''
https://water.phila.gov/pool/files/fy23-npdes-annual-report.pdf.
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Although most point source discharges today are treated, treated
effluent can still contain high levels of ammonia nitrogen, which
depletes oxygen in the water as microbes oxidize ammonia into nitrite,
nitrate, and dinitrogen gas.\25\ During the reporting periods from July
through October 2023, major wastewater treatment facilities along the
Delaware River discharged ammonia nitrogen at monthly average
concentrations ranging from a low of 0.1 milligrams nitrogen per liter
(mg-N/L) at the Easton Area Joint Sewer Authority in Pennsylvania
(discharging into Zone 1 of the Delaware River) to a high of 34.5 mg-N/
L at the Gloucester County Utilities Authority in New Jersey
(discharging into Zone 4 of the Delaware River).\26\ The effect of any
one discharge on dissolved oxygen in the river depends on a variety of
factors, including the discharge concentration, the magnitude of the
discharge, the location of the discharge, and conditions in the river,
which may also be affected by other dischargers.
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\25\ United States Environmental Protection Agency. (2023b).
Ammonia. https://www.epa.gov/caddis-vol2/ammonia.
\26\ Each individual reporting period is one month long. For the
reporting periods ending on August 31, 2023, and October 31, 2023,
the Easton Area Joint Sewer Authority discharged an average of 0.1
mg/L of ammonia. For the reporting period ending on August 31, 2023,
the Gloucester County Utilities Authority discharged an average of
34.5 mg/L of ammonia. Source: U.S. Environmental Protection Agency.
Integrated Compliance Information System (ICIS). Database. Retrieved
May 22, 2024.
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2. Endangered Species in the Specified Zones of the Delaware River
The Delaware River is home to multiple oxygen-sensitive fish
species, two of which--Shortnose Sturgeon and Atlantic Sturgeon--are
protected under the Federal Endangered Species Act (ESA). All
populations of Shortnose Sturgeon have been listed as endangered since
1967.\27\ Across the U.S., Shortnose Sturgeon face ongoing threats due
to water pollution, among other factors.\28\ While the historic
population size of Shortnose Sturgeon in the Delaware River remains
unknown, in 2006 the Delaware River population was estimated to be
approximately 12,000 adults.\29\
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\27\ Federal Register, Vol. 32, No. 48 (32 FR 4000). March 11,
1967. https://www.fisheries.noaa.gov/s3//2022-12/4000-4002.pdf.
\28\ NMFS. (2023a). Shortnose Sturgeon--Overview. https://www.fisheries.noaa.gov/species/shortnose-sturgeon.
\29\ Id.; NMFS. (2023b). Shortnose Sturgeon--Populations.
https://www.fisheries.noaa.gov/species/shortnose-sturgeon#populations.
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The New York Bight distinct population segment (DPS) of Atlantic
Sturgeon--which includes the population found in the Delaware River--
was listed as endangered under the ESA in 2012.\30\ In 2017, the
National Oceanic and Atmospheric Administration's National Marine
Fisheries Service (NMFS) designated the Delaware River, among others,
as critical habitat for the New York Bight DPS of Atlantic
Sturgeon,\31\ and reaffirmed its endangered listing status in 2022
following a five-year review.\32\ The remnant population of the New
York Bight DPS of Atlantic Sturgeon
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faces ongoing threats due to water quality in natal rivers, such as the
Delaware River, among other factors.33 34 Like the Shortnose
Sturgeon, the historic population size of Atlantic Sturgeon is not well
documented. However, in 1890, when the population was already
declining, there were approximately 180,000 female Atlantic Sturgeon in
the Delaware River.\35\ Despite improvements in dissolved oxygen levels
since the 1970s, it is estimated that only 125-250 adult (male and
female) Atlantic Sturgeon currently return to spawn in the Delaware
River.\36\
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\30\ Federal Register, Vol. 77, No. 24 (77 FR 5879). February 6,
2012. https://www.federalregister.gov/documents/2012/02/06/2012-1946/endangered-and-threatened-wildlife-and-plants-threatened-and-endangered-status-for-distinct.
\31\ Federal Register, Vol. 82, No. 158 (82 FR 39160). August
17, 2017. 50 CFR part 226. https://www.federalregister.gov/documents/2017/08/17/2017-17207/endangered-and-threatened-species-designation-of-critical-habitat-for-the-endangered-new-york-bight.
\32\ National Marine Fisheries Service. (2022). New York Bight
Distinct Population Segment of Atlantic Sturgeon (Acipenser
oxyrinchus oxyrinchus), 5-Year Review: Summary and Evaluation.
February 17, 2022. https://www.fisheries.noaa.gov/resource/document/new-york-bight-distinct-population-segment-atlantic-sturgeon-5-year-review.
\33\ Ibid. See Section 2.3.2, ``Five-Factor Analysis (threats,
conservation measures, and regulatory mechanisms)'', A. through E.,
pp. 14-25.
\34\ Dunton, K.J., Jordaan, A., Conover, D.O., McKown, K.A.,
Bonacci, L.A., and Frisk, M.G. (2015). Marine Distribution and
Habitat Use of Atlantic Sturgeon in New York Lead to Fisheries
Interactions and Bycatch. Marine and Coastal Fisheries 7:18-32.
https://doi.org/10.1080/19425120.2014.986348;
Atlantic Sturgeon Bycatch Working Group. (2022). Action Plan to
Reduce Atlantic Sturgeon Bycatch in Federal Large Mesh Gillnet
Fisheries. NOAA National Marine Fisheries Service. https://media.fisheries.noaa.gov/2022-09/Final-Action-Plan-to-Reduce-Atlantic-Sturgeon-Bycatch.pdf.
\35\ Secor and Waldman (1999).
\36\ White, S.L., Sard, N.M., Brundage, H.M., Johnson, R.L.,
Lubinski, B.A., Eackles, M.S., Park, I.A., Fox, D.A., and Kazyak,
D.C. (2022). Evaluating Sources of Bias in Pedigree-Based Estimates
of Breeding Population Size. Ecological Applications 32(5): e2602.
https://doi.org/10.1002/eap.2602.
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In addition to being listed as endangered under the ESA, available
evidence suggests that Shortnose Sturgeon and Atlantic Sturgeon are the
most oxygen-sensitive species in the specified zones of the Delaware
River. In general, all sturgeon species share common physiological
traits,\37\ which include being relatively more sensitive to low
dissolved oxygen levels than other co-occurring fish.38 39
Sturgeon are considered unusually sensitive to hypoxia (i.e., low
oxygen) given their documented metabolic and behavioral responses and
limited ability to oxyregulate.\40\ Juvenile Atlantic Sturgeon are
particularly sensitive to low dissolved oxygen levels, especially at
high water temperatures,\41\ such as those typically present at the
peak of summer in the Delaware River.\42\ A literature review across
oxygen-sensitive species in the Delaware River indicates that Atlantic
Sturgeon, particularly juveniles, have the highest documented dissolved
oxygen requirements for growth and survival when compared to other
oxygen-sensitive species in the specified zones of the Delaware
River.\43\ In its five-year review of the listing of the New York Bight
DPS of Atlantic Sturgeon, NMFS observed a continuation of low dissolved
oxygen conditions in known Atlantic Sturgeon juvenile rearing habitat
in the Delaware River.\44\ Juvenile Atlantic Sturgeon seeking relief
from areas with low oxygen may move to waters that limit their growth
due to other factors, such as reduced prey availability.\45\ NMFS also
noted studies showing fewer juvenile Atlantic Sturgeon captured in the
Delaware River in the fall when the preceding summer dissolved oxygen
levels were low, providing further evidence that low dissolved oxygen
levels are a contributor to the mortality of juvenile Atlantic
Sturgeon.\46\
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\37\ Federal Register, Vol. 82, No. 158 (82 FR 39161). August
17, 2017. 50 CFR part 226. pp. 39161-39163. https://www.federalregister.gov/documents/2017/08/17/2017-17207/endangered-and-threatened-species-designation-of-critical-habitat-for-the-endangered-new-york-bight.
\38\ Ibid. p. 39162, see Dees (1961), Sulak and Clugston (1999),
Billard and Lecointre (2001), Secor and Niklitschek (2002), and
Pikitch et al. (2005), cited therein.
\39\ Stoklosa et al. (2018); Secor, D.H. and Niklitschek, E.J.
(2001). Hypoxia and Sturgeons: Report to the Chesapeake Bay Program
Dissolved Oxygen Criteria Team. March 29, 2001. Reference Number:
[UMCES] CBL 01-0080. https://www.researchgate.net/publication/277065759_Hypoxia_and_Sturgeons_report_to_the_Chesapeake_Bay_Program_Dissolved_Oxygen_Criteria_Team.
\40\ Secor and Niklitschek (2001). Oxyregulation refers to an
organism's ability to maintain metabolic rates as the oxygen level
in the water declines.
\41\ Secor, D., and T. Gunderson. (1998). Effects of hypoxia and
temperature on survival, growth, and respiration of juvenile
Atlantic sturgeon, Acipenser oxyrinchus. Fishery Bulletin 96:603-
613;
Niklitschek, E. (2001). Bioenergetics modeling and assessment of
suitable habitat for juvenile Atlantic and shortnose sturgeons
(Acipenser oxyrinchus and A. brevirostrum) in the Chesapeake Bay.
University of Maryland at College Park.
\42\ More information is available in the associated document,
Technical Support Document for the Final Rule: Water Quality
Standards to Protect Aquatic Life in the Delaware River.
\43\ Stoklosa et al. (2018).
\44\ National Marine Fisheries Service (2022). See Section
2.3.2.1, ``Present or threatened destruction, modification, or
curtailment of its habitat or range.''
\45\ Ibid. See Allen et al. (2014), cited therein.
\46\ Ibid. See Moberg and DeLucia (2016), Stetzar et al. (2015),
and Park (2020), cited therein.
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3. Dissolved Oxygen Trends in the Specified Zones of the Delaware River
Dissolved oxygen levels in the relevant zones of the Delaware River
mirror trends in historic pollutant loading and recent pollution
control efforts in the river. Average summer dissolved oxygen levels in
the Delaware River near Chester, Pennsylvania (Zone 4) declined from
near saturation in the late 1880s to near zero (i.e., anoxia) in the
1950s and 1960s.\47\ Starting in 1970, dissolved oxygen levels began to
increase steadily following reductions in carbonaceous biological
oxygen demand from wastewater treatment plants.\48\ Ammonia nitrogen
concentrations in the Delaware River declined contemporaneously while
nitrate concentrations increased,\49\ which likely reflects increased
nitrification rates in the river, enabled by increased dissolved oxygen
concentrations. Reductions in nutrient concentrations, including
ammonia nitrogen, have been documented across the Delaware River
watershed through at least 2018.\50\ However, dissolved oxygen levels
in the summer are not yet high enough to avoid continued limitations on
the growth and survival of oxygen-sensitive species, such as juvenile
Atlantic Sturgeon.\51\ Recent modeling studies have shown that further
reductions in pollutant loading, including enhanced treatment of
ammonia nitrogen discharges and, to a lesser extent, a reduction in the
volume and frequency of CSOs, could significantly improve the dissolved
oxygen conditions in the relevant zones of the Delaware River.\52\
Accordingly, this could better support the growth and survival of
oxygen-sensitive species.
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\47\ Sharp, J. (2010). Estuarine oxygen dynamics: What can we
learn about hypoxia from long-time records in the Delaware estuary?
Limnology and Oceanography, 55(2), 535-548.
\48\ Albert, R.C. (1988). The Historical Context of Water-
Quality Management for the Delaware Estuary. Estuaries 11(2): 99-
107.
\49\ Sharp (2010).
\50\ Shoda, M.E., and Murphy, J.C. (2022). Water-quality trends
in the Delaware River Basin calculated using multisource data and
two methods for trend periods ending in 2018. U.S. Geological Survey
Scientific Investigations Report 2022-5097. https://doi.org/10.3133/sir20225097.
\51\ More information is available in the associated document,
Technical Support Document for the Final Rule: Water Quality
Standards to Protect Aquatic Life in the Delaware River;
Delaware River Basin Commission (2024a); Niklitschek, E., and D.
Secor. (2009a). Dissolved oxygen, temperature and salinity effects
on the ecophysiology and survival of juvenile Atlantic sturgeon in
estuarine waters: I. Laboratory results. Journal of Experimental
Marine Biology and Ecology 381:S150-S160. https://doi.org/10.1016/j.jembe.2009.07.018; Stoklosa et al. (2018).
\52\ Delaware River Basin Commission (2024a, 2024b).
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[[Page 46487]]
C. Administration of Water Quality Standards in the Delaware River
In 1961, the Delaware River Basin Compact established the Delaware
River Basin Commission (DRBC), comprised of the states of Delaware, New
Jersey, New York, and Pennsylvania and the Federal Government, to
jointly manage the Delaware River Basin's water resources.\53\ Through
the DRBC, each state participates in the shared governance of this
regional resource and maintains sovereign rights over the portion of
the river within its jurisdiction.\54\ This final rule is not
applicable to the upstream portions of the Delaware River under New
York's jurisdiction and neither the EPA nor the DRBC presently have
data or information indicating that sources of pollution in New York's
upstream waters would impact dissolved oxygen levels in the downstream
specified zones.
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\53\ The DRBC was established pursuant to Federal law (75 Stat.
688 (1961)).
\54\ Delaware River Basin Compact, art. 1, ``Short Title,
Definitions, Purpose and Limitations,'' Sec. 1.3(a), (b), & (c)
``Purpose and Findings,'' pp. 3 & 4, and art. 5, ``Pollution
Control,'' Sec. 5.5(b), ``Further Jurisdiction,'' p. 11, (1961),
available at https://www.nj.gov/drbc/library/documents/compact.pdf.
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Pursuant to the Delaware River Basin Compact, the DRBC adopts WQS
for interstate waters, including the Delaware River.\55\ However as
noted above, under the CWA, states have the primary responsibility for
reviewing, establishing, and revising WQS applicable to their waters,
and must submit new or revised WQS to the EPA for review and approval
or disapproval. Accordingly, WQS for the Delaware River are submitted
to the EPA for review through a process coordinated across the state,
regional, and Federal levels. This process begins when the DRBC adopts
WQS for the Delaware River. To comply with CWA section 303(c),
Delaware, New Jersey, and Pennsylvania have provisions in their state
WQS regulations that explicitly reference or implicitly incorporate the
DRBC's WQS as the applicable WQS for the portions of the Delaware River
under their jurisdictions. When the DRBC adopts new or revised WQS,
each relevant member state submits a certification to the EPA from that
state's attorney general or other appropriate legal authority, in
accordance with 40 CFR 131.6(e). Those certifications provide that the
DRBC's new or revised WQS were duly adopted pursuant to state law. The
EPA then reviews those WQS for consistency with the requirements of the
CWA pursuant to CWA section 303(c)(3).
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\55\ Delaware River Basin Compact, art. 5, ``Pollution
Control,'' Sec. 5.2, ``Policy and Standards,'' p. 11 (1961),
available at https://www.nj.gov/drbc/library/documents/compact.pdf
(DRBC ``may adopt and from time to time amend and repeal rules,
regulations and standards to control . . . future pollution and
abate existing pollution''). The DRBC, the states, and the EPA refer
to these rules, regulations, and standards as equivalent to WQS
under the CWA. As such, the term WQS is used herein to refer to
these rules, regulations, and standards.
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D. Relevant Aquatic Life Designated Uses and Dissolved Oxygen Criteria
Prior to Promulgation of This Final Rule
In 1967, the DRBC adopted WQS for the zones of the Delaware River
included in this final rule.\56\ Based on the conditions of the
Delaware River at the time, the DRBC concluded that ``propagation of
fish'' was not an attainable use for the specified zones due to the
presence of industrial and municipal discharges and associated low
dissolved oxygen levels. Therefore, the DRBC adopted designated uses of
``maintenance of resident fish and other aquatic life,'' and ``passage
of anadromous fish,'' (table 2 of this preamble) and a year-round
numeric water quality criterion for dissolved oxygen of 3.5 mg/L as a
24-hour average, as well as a seasonal criterion of 6.5 mg/L, for these
zones of the Delaware River (table 3 of this preamble).57 58
Because these WQS provided for the ``maintenance'' and ``passage'' of
aquatic life (i.e., ``protection'') but not the ``propagation of fish,
shellfish and wildlife,'' these WQS do not protect those uses reflected
in CWA section 101(a)(2) or the uses to be considered under CWA section
303(c)(2)(A).
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\56\ Delaware River Basin Commission. (2013). Delaware River
Basin Water Code. https://www.nj.gov/drbc/library/documents/watercode.pdf.
\57\ Id.; Delaware River Basin Commission. (2015). ``Existing
Use Evaluation for Zones 3, 4, & 5 of the Delaware Estuary Based on
Spawning and Rearing of Resident and Anadromous Fishes.'' September
30, 2015. https://www.state.nj.us/drbc/library/documents/ExistingUseRpt_zones3-5_sept2015.pdf.
\58\ Anadromous fish are species that are born and reared as
juveniles in freshwater, migrate to marine waters where they spend
most of their adult lives, and return to their natal, freshwater
rivers to spawn.
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Prior to this final rule, the DRBC's 1967 WQS remained applicable
for CWA purposes for the specified zones of the Delaware River as
directly referred to or implicitly incorporated in Delaware's, New
Jersey's, and Pennsylvania's WQS.
1. Aquatic Life Designated Uses in the Specified Zones Prior to
Promulgation of the EPA's Final Rule
As described in section II.C. of this preamble, Delaware, New
Jersey, and Pennsylvania each has its own WQS for the specified zones
of the Delaware River under its jurisdiction. Prior to the EPA's final
rule, the aquatic life designated use for Delaware's portion of the
specified zones of the Delaware River included all life stages,
including the propagation component of the CWA section 101(a)(2) use.
Prior to the EPA's final rule, the aquatic life designated use for New
Jersey's portions of the specified zones of the Delaware River
incorporated by reference the designated uses in the DRBC's Water
Quality Regulations. The aquatic life designated use for Pennsylvania's
portions of the specified zones of the Delaware River prior to the
EPA's final rule aligned with the DRBC's ``maintenance'' and
``passage'' designated use (table 2 of this preamble). Therefore,
before this final rule, the aquatic life designated uses for New
Jersey's and Pennsylvania's portions of the specified zones of the
Delaware River did not include the propagation component of the CWA
section 101(a)(2) use.
[[Page 46488]]
Table 2--Aquatic Life Designated Uses for the Mainstem Delaware River in
Zone 3, Zone 4, and Upper-Zone 5 Prior to the Promulgation of the EPA's
Final Rule
------------------------------------------------------------------------
Entity Designated use
------------------------------------------------------------------------
DRBC \59\.................... Maintenance of resident fish and other
aquatic life, passage of anadromous
fish, wildlife.
Delaware \60\................ Fish, Aquatic Life & Wildlife.\61\
New Jersey \62\.............. The designated uses for the mainstem
Delaware River and Delaware Bay are
those contained in the DRBC Water
Quality Regulations.
Pennsylvania \63\............ Warm Water Fishes (Maintenance Only);
Migratory fishes (Passage Only).\64\
------------------------------------------------------------------------
2. Previously Applicable Dissolved Oxygen Criteria in the Specified
Zones
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\59\ Delaware River Basin Commission. ``Administrative Manual--
Part III Water Quality Regulations with Amendments Through December
7, 2022.'' Accessed August 7, 2024. https://www.nj.gov/drbc/library/documents/WQregs.pdf.
\60\ Delaware Administrative Code. ``7401 Surface Water Quality
Standards.'' Title 7 Natural Resources & Environmental Control.
Delaware Department of Natural Resource and Environmental Control.
Accessed August 7, 2024. https://regulations.delaware.gov/AdminCode/title7/7000/7400/7401.pdf.
\61\ Delaware defines Fish, Aquatic Life & Wildlife as, ``all
animal and plant life found in Delaware, either indigenous or
migratory, regardless of life stage or economic importance.'' A
footnote specifies that this use includes shellfish propagation.
\62\ New Jersey Administrative Code. ``N. J. A. C. 7:9B Surface
Water Quality Standards.'' Accessed August 7, 2024. https://dep.nj.gov/wp-content/uploads/rules/rules/njac7_9b.pdf.
\63\ Pennsylvania Code. ``Chapter 93. Water Quality Standards.''
Commonwealth of Pennsylvania. Accessed August 7, 2024. https://www.pacodeandbulletin.gov/secure/pacode/data/025/chapter93/025_0093.pdf.
\64\ Pennsylvania defines its ``Warm Water Fishes'' designated
use as, ``Maintenance and propagation of fish species and additional
flora and fauna which are indigenous to a warm water habitat'' and
defines its ``Migratory Fishes'' designated use as, ``Passage,
maintenance and propagation of anadromous and catadromous fishes and
other fishes which move to or from flowing waters to complete their
life cycle in other waters.'' For the specified zones of the
Delaware River, Pennsylvania excluded propagation from the
designated uses by specifying ``Maintenance Only'' and ``Passage
Only'' in parentheses.
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For dissolved oxygen in the relevant zones, all three states
incorporated the DRBC's water quality criteria by reference; therefore,
prior to this final rule, the DRBC's dissolved oxygen criteria were the
applicable criteria for the relevant zones in each state for CWA
purposes (table 3 of this preamble). As explained above with respect to
the aquatic life designated use, the DRBC's dissolved oxygen criteria
for the specified zones of the Delaware River do not protect aquatic
life propagation and therefore do not protect those uses reflected in
CWA section 101(a)(2) or the uses to be considered under CWA section
303(c)(2)(A).
Table 3--Previously Applicable Dissolved Oxygen Criteria for the
Mainstem Delaware River in Zone 3, Zone 4, and Upper-Zone 5
------------------------------------------------------------------------
Entity Dissolved oxygen aquatic life criteria
------------------------------------------------------------------------
DRBC \65\.................... 24-hour average concentration shall not
be less than 3.5 mg/l. During the
periods from April 1 to June 15, and
September 16 to December 31, the
dissolved oxygen shall not have a
seasonal average less than 6.5 mg/l in
the entire zone.
Delaware \66\................ For waters of the Delaware River and
Delaware Bay, duly adopted Delaware
River Basin Commission (DRBC) Water
Quality Regulations shall be the
applicable criteria.
New Jersey \67\.............. For parameters with criteria in the DRBC
Water Quality Regulations, the criteria
contained therein are the applicable
criteria.
Pennsylvania \68\............ See DRBC Water Quality Regulations.
------------------------------------------------------------------------
3. Intersection of Delaware's, New Jersey's, and Pennsylvania's Aquatic
Life Designated Uses and Dissolved Oxygen Criteria With the CWA Prior
to the Promulgation of the EPA's Final Rule
---------------------------------------------------------------------------
\65\ Delaware River Basin Commission. ``Administrative Manual--
Part III Water Quality Regulations with Amendments Through December
7, 2022.'' Accessed August 7, 2024. https://www.nj.gov/drbc/library/documents/WQregs.pdf.
\66\ Delaware Administrative Code. ``7401 Surface Water Quality
Standards.'' Title 7 Natural Resources & Environmental Control.
Delaware Department of Natural Resource and Environmental Control.
Accessed August 7, 2024. https://regulations.delaware.gov/AdminCode/title7/7000/7400/7401.pdf.
\67\ New Jersey Administrative Code. ``N. J. A. C. 7:9B Surface
Water Quality Standards.'' Accessed August 7, 2024. https://dep.nj.gov/wp-content/uploads/rules/rules/njac7_9b.pdf.
\68\ Pennsylvania Code. ``Chapter 93. Water Quality Standards.''
Commonwealth of Pennsylvania. Accessed August 7, 2024. https://www.pacodeandbulletin.gov/secure/pacode/data/025/chapter93/025_0093.pdf.
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Table 4 of this preamble provides a summary outlining whether,
prior to the EPA's final rule, the aquatic life designated uses in each
of the three states in the specified zones aligned with CWA section
101(a)(2) goals and consideration of such uses under CWA section
303(c)(2)(A), and whether each state's dissolved oxygen criteria were
protective of an aquatic life designated use that includes propagation.
As explained above, only Delaware included aquatic life propagation in
its designated uses for the specified zones of the Delaware River.
However, none of the three states' dissolved oxygen criteria for the
specified zones were protective of fish and shellfish propagation.
Prior to this final rule, none of the states, and by extension none of
the specified zones of the Delaware River, had WQS for aquatic life
that were consistent with the CWA section 101(a)(2) goals and the
consideration of such uses under CWA section 303(c)(2)(A).
[[Page 46489]]
Table 4--Intersection of Delaware's, New Jersey's, and Pennsylvania's Aquatic Life Designated Uses and Dissolved Oxygen Criteria With CWA 101(a)(2)
Goals Prior to the Promulgation of the EPA's Final Rule
--------------------------------------------------------------------------------------------------------------------------------------------------------
Applicable zone(s) of
State the mainstem Delaware Designated use included CWA section Dissolved oxygen criteria protective of
River 101(a)(2) propagation component aquatic life propagation
--------------------------------------------------------------------------------------------------------------------------------------------------------
Delaware........................... Upper-5............... Yes.......................................... No.
New Jersey......................... 3, 4, Upper-5......... No........................................... No.
Pennsylvania....................... 3, 4.................. No........................................... No.
--------------------------------------------------------------------------------------------------------------------------------------------------------
E. Summary of the EPA Administrator's Determination
On December 1, 2022, the EPA issued an Administrator's
Determination, pursuant to CWA section 303(c)(4)(B), finding that a
revised designated use to protect aquatic life propagation and
corresponding dissolved oxygen criteria to protect that use are
necessary in the specified zones of the Delaware River.\69\ The
Administrator's Determination can be accessed at https://www.epa.gov/wqs-tech/federally-promulgated-water-quality-standards-specific-states-territories-and-tribes.
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\69\ December 1, 2022. Letter from Radhika Fox, Assistant
Administrator, EPA Office of Water, to Steven J. Tambini, Executive
Director, Delaware River Basin Commission; Shawn M. Garvin,
Secretary, Delaware Department of Natural Resources and
Environmental Control; Shawn M. LaTourette, Commissioner, New Jersey
Department of Environmental Protection; and Ramez Ziadeh, Acting
Secretary, Pennsylvania Department of Environmental Protection.
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III. Final Water Quality Standards
A. Scope of the EPA's Rule
The EPA's rule applies to the mainstem Delaware River in Zone 3,
Zone 4, and the upper portion of Zone 5 (in total, river miles 108.4 to
70.0), for the states of Delaware, New Jersey, and Pennsylvania (table
5 of this preamble). In the final rule, the EPA made a non-substantive
change to add the word ``mainstem'' to paragraphs (a)(1) and (2) and
(d)(1) and (2) to clarify the scope of the rule, in response to
comments requesting such clarification.
Table 5--Zones Corresponding With the Mainstem Delaware River Covered by
the EPA's Rule
------------------------------------------------------------------------
Segment of the Delaware River River miles States affected
------------------------------------------------------------------------
Zone 3.......................... 108.4 to 95.0..... New Jersey,
Pennsylvania.
Zone 4.......................... 95.0 to 78.8...... New Jersey,
Pennsylvania.
Zone 5--Upper Portion........... 78.8 to 70.0...... Delaware, New
Jersey.
------------------------------------------------------------------------
B. Aquatic Life Designated Use
The EPA is promulgating an aquatic life designated use of
``Protection and propagation of resident and migratory aquatic life''
for the specified zones in New Jersey and Pennsylvania that is
consistent with CWA section 101(a)(2) goals and reflects the
considerations for setting WQS in CWA section 303(c)(2)(A). This is the
same aquatic life designated use that the EPA proposed for the portions
of the affected zones in these two states.\70\ Several commenters
supported the EPA's proposal to upgrade the designated uses of the
specified zones of the Delaware River to include propagation of
resident and migratory aquatic life, and some of these commenters
asserted that such an upgrade is legally and scientifically mandated.
Additionally, some commenters asserted that the designated use upgrade
and stronger dissolved oxygen criteria are essential to protect aquatic
life in the specified zones of the Delaware River, including the
endangered sturgeon, and to support recreational and commercial
fishing. Some commenters asserted that fish, including the endangered
Atlantic Sturgeon and Shortnose Sturgeon, have been propagating in the
specified zones for many years. No commenters opposed the EPA's
proposed aquatic life designated use.
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\70\ United States Environmental Protection Agency. (2023).
Water Quality Standards to Protect Aquatic Life in the Delaware
River. Proposed Rule. 88 FR 88315. December 21, 2023.
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CWA section 303(c) assigns states the primary role in adopting WQS;
accordingly, the EPA evaluated the aquatic life uses for the relevant
zones on a state-by-state basis and proposed a revised use only for New
Jersey and Pennsylvania consistent with CWA section 303(c)(2)(A)'s
instruction to take into consideration the use of waters for
``propagation of fish and wildlife.'' As explained in section II.D. of
this preamble, Delaware's ``Fish, Aquatic Life & Wildlife'' designated
use includes all life stages of indigenous and migratory organisms;
therefore, for the specified zones under its jurisdiction, Delaware's
aquatic life designated use is already consistent with the CWA's
101(a)(2) goals and the considerations in CWA section 303(2)(c)(A) and
no revisions to the aquatic life designated uses in Delaware's portion
of the specified zones are necessary. In contrast, New Jersey's and
Pennsylvania's aquatic life designated uses for the relevant zones of
the Delaware River under their jurisdiction do not include
``propagation'' and therefore do not fully achieve the CWA's 101(a)(2)
goals or reflect the considerations in CWA section 303(c)(2)(A). As
explained in section II.E. of this preamble, the EPA determined that
propagation is an attainable use in the specified zones of the Delaware
River.\71\ Thus, the EPA is promulgating an aquatic life designated use
that includes propagation for New Jersey and Pennsylvania's portions of
the mainstem Delaware River in Zone 3, Zone 4, and the upper portion of
Zone 5 (in total, river miles 108.4 to 70.0).
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\71\ December 1, 2022. Letter from Radhika Fox, Assistant
Administrator, EPA Office of Water, to Steven J. Tambini, Executive
Director, Delaware River Basin Commission; Shawn M. Garvin,
Secretary, Delaware Department of Natural Resources and
Environmental Control; Shawn M. LaTourette, Commissioner, New Jersey
Department of Environmental Protection; and Ramez Ziadeh, Acting
Secretary, Pennsylvania Department of Environmental Protection.
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One commenter asked the EPA whether the propagation designated use
in the EPA's rule is equivalent to Pennsylvania's Warm Water Fishes
(WWF) use to help Pennsylvania evaluate which of its WWF aquatic life
criteria could apply to protect the new Federal designated use.
Pennsylvania's WWF use is one of the state's EPA-approved aquatic life
uses.
[[Page 46490]]
Pennsylvania's WQS define the WWF use as ``[m]aintenance and
propagation of fish species and additional flora and fauna which are
indigenous to a warm water habitat,'' and identify various criteria
associated with the WWF use.\72\ The WWF use is consistent with the CWA
and applies to warm waters in Pennsylvania but does not apply to the
zones of the Delaware River affected by this rulemaking. As discussed
in section II.D. of this preamble, Pennsylvania's currently applicable
designated uses for the zones covered by this rule are ``WWF
(maintenance only)'' and ``Migratory Fishes (passage only).''
Pennsylvania has not established its own criteria to protect these
uses. Therefore, the currently applicable criteria for Pennsylvania's
portions of these zones are the DRBC's criteria for Zones 3 and 4,
which Pennsylvania has adopted by reference.
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\72\ Pennsylvania Code. ``Chapter 93. Water Quality Standards.''
Commonwealth of Pennsylvania. Accessed August 7, 2024. https://www.pacodeandbulletin.gov/secure/pacode/data/025/chapter93/025_0093.pdf.
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Pennsylvania's WWF use and criteria are outside the scope of this
rulemaking. This is because Pennsylvania's WWF designated use and the
EPA-approved aquatic life criteria associated with Pennsylvania's WWF
use do not currently apply for CWA purposes to the specified zones of
the Delaware River for which EPA is promulgating the designated use and
associated dissolved oxygen criteria in this rule. If Pennsylvania
would like to apply its WWF use and criteria to Pennsylvania's portions
of the specified zones of the Delaware River, it could revise its state
WQS and submit that revision to the EPA for CWA section 303(c) review.
The EPA is available to provide Pennsylvania with technical support on
any such future WQS revisions.
The EPA reiterates that the CWA vests the primary responsibility
for developing WQS in the states, and that states have substantial
discretion in designating uses consistent with the CWA's emphasis on
cooperative federalism. CWA section 303(c)(2)(A), for example, provides
that states must establish WQS for waters within their jurisdiction
``taking into consideration their use and value for public water
supplies, propagation of fish and wildlife, recreational purposes, and
agricultural, industrial, and other purposes,'' thereby providing
states discretion in selecting the uses to designate. In this rule,
under the circumstances here, as authorized by CWA section
303(c)(4)(B), the EPA is finalizing a designated use that is attainable
and consistent with the CWA.
C. Dissolved Oxygen Criteria To Protect Aquatic Life Propagation
The EPA is establishing dissolved oxygen criteria largely as
proposed for Delaware, New Jersey, and Pennsylvania, for the specified
zones of the Delaware River based on a sound scientific rationale. The
dissolved oxygen criteria protect the EPA's promulgated designated use
for New Jersey and Pennsylvania, as well as Delaware's current aquatic
life designated use for the specified zones.
1. Derivation of Dissolved Oxygen Criteria
To derive protective dissolved oxygen criteria for the specified
zones of the Delaware River, the EPA used methods adapted from peer-
reviewed literature and data from laboratory studies relevant to
oxygen-sensitive sturgeon species in the Delaware River. Although the
methods and data are from peer-reviewed scientific literature, the EPA
nonetheless completed an external peer review on the data and
application of these methods to develop the criteria; the peer review
and the EPA's response to the peer review comments are available in the
docket for this rulemaking. This section presents a summary of the data
and methods that the EPA used to derive protective dissolved oxygen
criteria for this final rule. First, the EPA describes the Agency's
existing dissolved oxygen national recommendations and guidance
documents. Then, the EPA explains how the Agency selected three seasons
to derive criteria protective of oxygen-sensitive species in the
relevant zones of the Delaware River. Next, the EPA details an Atlantic
Sturgeon cohort model it used to derive criteria protective of juvenile
Atlantic Sturgeon during the season associated with their growth and
development. After that, the EPA explains how the Agency developed
criteria to protect oxygen-sensitive species during the other two
seasons. Lastly, the EPA concludes with an explanation for promulgating
criteria expressed as percent oxygen saturation, rather than as
concentration.
This section is intended to be a high-level summary of the EPA's
criteria derivation methods and results for this final rule. While the
EPA utilized the below described methodologies for finalizing these
criteria, states may use different approaches so long as the resulting
criteria are protective of the relevant designated uses \73\ and based
on sound scientific rationale, as provided in the regulations.\74\ More
details and information are available in the associated document,
Technical Support Document for the Final Rule: Water Quality Standards
to Protect Aquatic Life in the Delaware River.
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\73\ CWA section 303(c)(2)(A).
\74\ 40 CFR 131.11(a).
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Existing EPA Methodology and Guidance Documents
Under CWA section 304(a), the EPA publishes, from time to time,
national recommended aquatic life criteria for a variety of pollutants
and parameters. The EPA's national recommended criteria for dissolved
oxygen in freshwater and saltwater environments are from the 1986
Quality Criteria for Water (``Gold Book'') \75\ and the 2000 Ambient
Aquatic Life Water Quality Criteria for Dissolved Oxygen (Saltwater):
Cape Cod to Cape Hatteras (``Virginian Province Document''),\76\
respectively. The EPA's recommendations in the Virginian Province
Document state that, ``in cases where a threatened or endangered
species occurs at a site, and sufficient data exist to suggest that it
is more sensitive at concentrations above the criteria, it is
appropriate to consider development of site-specific criteria based on
this species.'' \77\
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\75\ United States Environmental Protection Agency. (1986).
Quality Criteria for Water 1986. Document ID: EPA 440/5-86-001. May
1, 1986. https://www.epa.gov/sites/default/files/2018-10/documents/quality-criteria-water-1986.pdf.
\76\ United States Environmental Protection Agency. (2000).
Ambient Aquatic Life Water Quality Criteria for Dissolved Oxygen
(Saltwater): Cape Cod to Cape Hatteras. Document ID: EPA-822-R-00-
012. November 2000. https://www.epa.gov/sites/default/files/2018-10/documents/ambient-al-wqc-dissolved-oxygen-cape-code.pdf.
\77\ Id. Page 41.
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As explained previously in section II.B. of this preamble, Atlantic
Sturgeon and Shortnose Sturgeon are federally listed as endangered
under the ESA and are uniquely sensitive to hypoxia. Given the
availability of laboratory data specific to the oxygen requirements of
Atlantic Sturgeon and Shortnose Sturgeon, the EPA chose to derive site-
specific criteria to protect the oxygen-sensitive endangered species in
the specified zones of the Delaware River and did not rely on the
national recommendations in the Gold Book or Virginian Province
Document to derive criteria in this instance. While some commenters
cited the Gold Book or Virginian Province Document as support for their
assertions that the EPA's proposed criteria were too stringent or not
stringent enough, no commenter suggested that the EPA promulgate
criteria values directly from either of those documents.
[[Page 46491]]
Delineating Seasons for Criteria Derivation
Given available information, including information developed by the
DRBC, the EPA delineated three distinct seasons for dissolved oxygen
criteria development that are intended to protect Atlantic Sturgeon
throughout their life history, while also protecting a range of other
aquatic species during their sensitive early life histories in the
specified zones. For this rule, the EPA defines the Spawning and Larval
Development season as occurring from March 1 to June 30, which
generally covers spawning and egg and larval development periods for
many oxygen-sensitive species, including Atlantic Sturgeon, Shortnose
Sturgeon, American Shad, Atlantic Rock Crab, Channel Catfish, Striped
Bass, Largemouth Bass, White Perch, and Yellow Perch.\78\ The EPA
defines the Juvenile Development season in this final rule as occurring
from July 1 to October 31 and the Overwintering season as occurring
from November 1 to February 28/29, based on young-of-the-year juvenile
Atlantic Sturgeon growth rates.\79\ By November, oxygen levels are
relatively high and not expected to limit growth and survival, a
characteristic of the overwintering period.\80\ While the EPA defines
seasons for this rule largely based on the life history of Atlantic
Sturgeon, these seasons also generally correspond with early life
histories of other oxygen-sensitive species in the specified zones of
the Delaware River. By developing criteria that are protective of
Atlantic Sturgeon, which, as described in section II.B. of this
preamble, is the most oxygen-sensitive species in the relevant zones of
the Delaware River, the EPA concluded that the criteria will also be
protective of other less oxygen-sensitive resident and migratory
aquatic species in the specified zones of the Delaware River. While not
the only appropriate way to develop such criteria, the EPA determined
that this approach is appropriate and scientifically sound under the
circumstances.
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\78\ Stoklosa et al. (2018); Delaware River Basin Commission
(2015); Moberg, T. and M. DeLucia. (2016). Potential Impacts of
Dissolved Oxygen, Salinity and Flow on the Successful Recruitment of
Atlantic Sturgeon in the Delaware River. The Nature Conservancy.
https://www.conservationgateway.org/ConservationPractices/Freshwater/HabitatProtectionandRestoration/Documents/DelawareAtlanticSturgeonReport_TNC5172016.pdf.
\79\ Moberg and DeLucia. (2016).
\80\ Additional information is described in sections 3.3.3 and
4.1.2 of the associated document, Technical Support Document for the
Final Rule: Water Quality Standards to Protect Aquatic Life in the
Delaware River.
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The EPA received several comments requesting that the Agency
finalize dissolved oxygen criteria based on monthly periods rather than
the seasons that the EPA proposed. Many of these commenters asserted
that the EPA's seasonal approach could result in too many days during
which the criteria could be exceeded and expressed concerns about the
impact of those exceedances on aquatic life. These commenters asserted
that monthly assessment periods would reduce the number of consecutive
days where dissolved oxygen could be below protective levels.
Additionally, one commenter asserted that the seasonal approach would
lead to challenges for organizations that monitor water quality and/or
assess attainment of applicable WQS, stating that the EPA's criteria
cannot be adequately assessed with grab samples collected once or twice
a month and continuous monitoring data can be time-consuming and
prohibitively expensive to collect.
As discussed below in this section of the preamble, the EPA's
approach for deriving dissolved oxygen criteria in this instance is
based on defining suitable habitat conditions as those that provide
each year's juvenile cohort the potential to increase its biomass
during the season. Developing criteria that would apply at a monthly
interval would require the EPA to specify a scientifically defensible
operational definition, in accordance with the CWA and the EPA's
implementing regulations, of supporting the propagation designated use
for each month, rather than for the season. Commenters did not provide
an explanation or technical rationale for how the EPA could define
suitable habitat in each month. The EPA also could not identify such an
operational definition because propagation is ecologically a seasonal
process and the amount of dissolved oxygen required in each month may
depend on what the fish are exposed to in other months. Therefore, the
EPA concluded that retaining the seasonal criteria approach applied
sound scientific information to ensure the propagation designated use
is protected.
The EPA acknowledges that each four-month season allows for the
dissolved oxygen criteria to be exceeded for up to 12 days during the
season.\81\ However, the EPA's empirical approach in this rulemaking
ensures that the criteria are set at a level that is expected to
protect aquatic life propagation despite these potential exceedances.
As described in detail below (and in the associated technical support
document and response to comments document), when the seasonal 10th
percentile of oxygen saturation meets the EPA's criteria, the Agency
expects that the oxygen saturation values on the 12 days with the
lowest daily average oxygen level will not be low enough to prevent
attainment of the designated use.
---------------------------------------------------------------------------
\81\ Additionally, for the Juvenile Development season the
dissolved oxygen criteria at the 50% exceedance frequency can be
exceeded up to 61 days.
---------------------------------------------------------------------------
Consistent with the EPA's implementing regulations at 40 CFR
131.11(a), the EPA developed the dissolved oxygen criteria based on
sound science to protect an aquatic life designated use that includes
propagation. Regarding comments suggesting that the Agency's seasonal
approach presents an obstacle to water quality assessments, the EPA has
identified potential strategies that could be used to assess attainment
of the Federal criteria. The EPA concluded that the seasonal structure
of the dissolved oxygen criteria will not impede assessment of the
EPA's criteria in the specified zones, regardless of the types of data
collected. For example, dissolved oxygen measurements could be needed
for as few as 13 days to demonstrate that there are more than 12 days
of exceedance and therefore to demonstrate non-attainment of the 10th
percentile criterion in a season. The publicly available water quality
data that have been collected in the specified zones by the DRBC and
the U.S. Geological Survey indicate which days and locations are least
likely to attain the criteria magnitudes. Thus, organizations that
monitor water quality could readily implement a targeted monitoring
strategy focused on the most critical times and locations, using
dissolved oxygen sensors (i.e., continuous measurements) or discrete
measurements. While the most precise assessment would rely on quality-
assured continuous measurements, a daily time series computed by
interpolation of discrete measurements could also provide valid
evidence to support an assessment decision. The DRBC and the U.S.
Geological Survey have maintained continuous monitoring at two
locations in the specified zones of the river since the 1960s, have
shared the data in near real-time, and have indicated that they intend
to maintain the continuous monitoring into the future. Therefore, the
EPA concluded that water quality assessments are feasible under the
seasonal criteria construct, and that such assessments could rely on
continuous data and/or discrete data collected by a wide array
[[Page 46492]]
of stakeholders. A more detailed discussion about monitoring and
assessment is available in the associated response to comments
document.
Ecological Modeling To Derive Criteria for the Juvenile Development
Season
The EPA obtained recent and high-quality data from a variety of
sources, described below and detailed in the associated technical
support document, to evaluate the oxygen requirements of juvenile
Atlantic Sturgeon. These data include measurements quantifying water
quality conditions at two locations in the specified zones of the
Delaware River. Since 2012 when the Atlantic Sturgeon was listed as an
endangered species, there have been few studies documenting the oxygen
requirements of this species. However, the EPA obtained sufficient data
to establish quantitative relationships between age-0 juvenile sturgeon
(Atlantic Sturgeon and Shortnose Sturgeon) growth, mortality, and
habitat suitability. These include data from Campbell and Goodman
(2004), Niklitschek and Secor (2009a), and EPA (2003), along with
methods from Niklitschek and Secor (2005) and Niklitschek and Secor
(2009b), water quality monitoring data, and juvenile Atlantic Sturgeon
abundance data from the Delaware Department of Natural Resources and
Environmental Control (DNREC).\82\
---------------------------------------------------------------------------
\82\ Campbell, J., and L. Goodman. (2004). Acute sensitivity of
juvenile shortnose sturgeon to low dissolved oxygen concentrations.
Transactions of the American Fisheries Society 133:722-776;
Niklitschek, E., and D. Secor. (2009a). Dissolved oxygen,
temperature and salinity effects on the ecophysiology and survival
of juvenile Atlantic sturgeon in estuarine waters: I. Laboratory
results. Journal of Experimental Marine Biology and Ecology
381:S150-S160. https://doi.org/10.1016/j.jembe.2009.07.018;
United States Environmental Protection Agency. (2003). Ambient
Water Quality Criteria for Dissolved Oxygen, Water Clarity and
Chlorophyll a for the Chesapeake Bay and its Tidal Tributaries.
Document ID: EPA 903-R-03-002. April 2003. https://nepis.epa.gov/Exe/ZyPDF.cgi/P100YKPQ.PDF?Dockey=P100YKPQ.PDF;
Niklitschek, E.J., and D.H. Secor. (2005). Modeling spatial and
temporal variation of suitable nursery habitats for Atlantic
sturgeon in the Chesapeake Bay. Estuarine, Coastal and Shelf Science
64:135-148. https://doi.org/10.1016/j.ecss.2005.02.012;
Niklitschek, E.J., and D.H. Secor. (2009b). Dissolved oxygen,
temperature and salinity effects on the ecophysiology and survival
of juvenile Atlantic sturgeon in estuarine waters: II. Model
development and testing. Journal of Experimental Marine Biology and
Ecology 381:S161-S172. https://doi.org/10.1016/j.jembe.2009.07.019;
USGS 01467200 Delaware River at Penn's Landing, Philadelphia,
PA. Retrieved March 9, 2023. https://waterdata.usgs.gov/nwis/inventory/?site_no=01467200&agency_cd=USGS;
USGS 01477050 Delaware River at Chester PA. Retrieved January
31, 2023. https://waterdata.usgs.gov/nwis/inventory?agency_code=USGS&site_no=01477050;
Park, I. (2023). State of Delaware Annual Compliance Report for
Atlantic Sturgeon. Delaware Division of Fish and Wildlife,
Department of Natural Resources and Environmental Control. September
2023.
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The EPA followed the peer-reviewed cohort modeling approach of
Niklitschek and Secor (2005) to evaluate the effects of temperature,
salinity, and dissolved oxygen on the potential growth and mortality of
a hypothetical cohort or group of juvenile Atlantic Sturgeon spawned
during a single year.\83\ The cohort model uses growth and mortality
rates to calculate the instantaneous daily production potential, or the
instantaneous daily rate of biomass production per unit of cohort
biomass per day. The EPA used the cohort model to estimate the fraction
of the cohort that could survive from July 1 through October 31 (i.e.,
the Juvenile Development season) and the relative change in biomass for
the same period.
---------------------------------------------------------------------------
\83\ Water temperature and salinity can affect the oxygen
requirements of aquatic species and are needed to compute percent
oxygen saturation, a measure of dissolved oxygen availability to
aquatic organisms, from dissolved oxygen concentrations.
---------------------------------------------------------------------------
As part of the cohort model, the EPA developed a new mortality
model and implemented a peer-reviewed bioenergetics-based growth model
described by Niklitschek and Secor (2009b) to predict the daily
instantaneous minimum mortality rate and potential growth rate,
respectively, for members of the cohort. To develop a mortality model,
the EPA fit a regression to experimental data to predict mortality
resulting from low dissolved oxygen at any given temperature and
percent oxygen saturation.\84\ Mortality rates of juvenile sturgeon
increased with declining dissolved oxygen levels and increased at
higher rates where there was both declining dissolved oxygen and
increasing water temperature. The EPA validated the results of the
mortality model by using observed water quality data from 2002-2022 to
predict the relative abundance of the Atlantic Sturgeon young-of-year
cohort on October 31 of each year and comparing those results to
available catch data from DNREC's juvenile abundance surveys.\85\ The
growth model takes a bioenergetic approach that accounts for
temperature-controlled maximum metabolic rates that may be further
limited by oxygen levels. Low oxygen levels limit overall metabolic
rates and cause a shift in the allocation of available energy away from
growth. Predicted growth rates reflect the balance between energy
inputs and losses and are therefore reduced by low oxygen. Water
quality monitoring data in the relevant zones of the Delaware River
show that the lowest oxygen levels coincided with the highest water
temperatures, resulting in lower growth rates than either condition
would cause alone.
---------------------------------------------------------------------------
\84\ Experimental data are from Campbell and Goodman 2004,
Niklitschek and Secor 2009a.
\85\ USGS 01467200 Delaware River at Penn's Landing,
Philadelphia, PA. Retrieved March 9, 2023. https://waterdata.usgs.gov/nwis/inventory/?site_no=01467200&agency_cd=USGS;
USGS 01477050 Delaware River at Chester PA. Retrieved January
31, 2023. https://waterdata.usgs.gov/nwis/inventory?agency_code=USGS&site_no=01477050; Park (2023).
---------------------------------------------------------------------------
Habitat Suitability Indices have been used in the context of fish-
habitat relationships, conservation management, and habitat evaluation
to quantify the capacity of a given habitat to support essential life
functions (e.g., growth, survival, reproduction) of a selected
species.\86\ At proposal, the EPA defined a Habitat Suitability Index
(HSI) for Atlantic Sturgeon as the instantaneous daily production
potential, which was calculated using the cohort model. The EPA
maintained that definition of HSI for the final rule. HSI evaluates the
combined effect of percent oxygen saturation, water temperature, and
salinity on the potential growth and survival of juvenile Atlantic
Sturgeon during the Juvenile Development season. The EPA used quantile
generalized additive models (QGAMs) to quantify relationships between
computed values of HSI in each year and corresponding seasonal
percentiles of daily average dissolved oxygen for that year.\87\ QGAMs
can model the non-linear relationship between dissolved oxygen and HSI
as well as predict the expected
[[Page 46493]]
median HSI, rather than the expected mean.
---------------------------------------------------------------------------
\86\ E.g., Woodland, R.J., Secor, D.H., and Niklitschek, E.J.
(2009). Past and Future Habitat Suitability for the Hudson River
Population of Shortnose Sturgeon: A Bioenergetic Approach to
Modeling Habitat Suitability for an Endangered Species. American
Fisheries Society Symposium 69: 589-604;
Collier, J.J., Chiotti, J.A., Boase, J., Mayer, C.M.,
Vandergoot, C.S., and Bossenbroek, J.M. (2022). Assessing habitat
for lake sturgeon (Acipenser fulvescens) reintroduction to the
Maumee River, Ohio using habitat suitability index models. Journal
of Great Lakes Research. 48(1): 219-228. https://doi.org/10.1016/j.jglr.2021.11.006;
Brown, S.K., Buja, K.R., Jury, S.H., Monaco, M.E., and Banner,
A. (2000). Habitat Suitability Index Models for Eight Fish and
Invertebrate Species in Casco and Sheepscot Bays, Maine. North
American Journal of Fisheries Management, 20(2): 408-435, https://doi.org/10.1577/1548-8675(2000)020%3C0408:HSIMFE%3E2.3.CO;2.
\87\ A percentile (e.g., 10th percentile) is the dissolved
oxygen level below which the corresponding fraction (e.g., 10%) of
the daily dissolved oxygen values during the season falls below. In
this case, the season is the Juvenile Development season (July 1 to
October 31).
---------------------------------------------------------------------------
The EPA followed the approach of Niklitschek and Secor (2005) to
define suitable habitat for juvenile Atlantic Sturgeon growth and
survival as habitat with water quality resulting in HSI greater than
zero. When HSI is less than or equal to zero, seasonal average
mortality rates are greater than or equal to seasonal average growth
rates and the overall biomass of the cohort is likely to decrease,
reducing the potential for propagation, or recruitment of juveniles to
the population. Conversely, a cohort of juveniles utilizing habitat
with HSI greater than zero has the potential to increase its biomass
during the Juvenile Development season, thus contributing to successful
propagation. Therefore, to derive protective dissolved oxygen criteria,
the EPA evaluated seasonal percentiles of daily average percent oxygen
saturation to find the lowest value at which the QGAMs predict expected
median HSI greater than zero as the minimum threshold for percent
oxygen saturation that, if attained, would provide suitable habitat
during that seasonal period.
The predicted HSI value relies on an expected distribution of daily
average percent oxygen saturation values during the season; therefore,
the EPA selected two percent oxygen saturation percentiles as
thresholds at or above which median HSI is expected to be greater than
zero to maintain the expected distribution of percent oxygen saturation
values. These two percentiles--the 10th percentile and the 50th
percentile--describe the protective seasonal distribution of daily
average dissolved oxygen values. When both the 10th percentile and 50th
percentile are attained, they function together to ensure that a
detrimental shift in the oxygen distribution (i.e., a shift causing
more low oxygen levels) at either the low end (10th percentile) or the
center (50th percentile) of the dissolved oxygen daily average
distribution has not occurred. Median HSI is expected to be zero or
higher, allowing the annual cohort of juvenile Atlantic Sturgeon to
maintain or increase its biomass, when the 10th percentile of daily
average oxygen saturation is at least 66% and the 50th percentile, or
median, of daily average oxygen saturation is at least 74%. Therefore,
the EPA expects oxygen levels will protect propagation of oxygen-
sensitive fish species during the Juvenile Development season if the
10th percentile of daily average oxygen saturation is at least 66% and
the 50th percentile of daily average oxygen saturation is at least 74%.
The EPA received several comments requesting that the Agency
finalize dissolved oxygen criteria that include an instantaneous
minimum criterion (i.e., a lower bound criterion that can never be
exceeded). Many of these commenters asserted that an instantaneous
minimum criterion was necessary to support propagation and protect
against high rates of mortality. While many commenters did not provide
a suggested magnitude for an instantaneous minimum criterion, a few
commenters suggested a minimum criterion of 6 mg/L.
The EPA recognizes that, unlike an instantaneous minimum criterion,
the 10th percentile criterion allows for 12 days of exceedance with no
lower bound. However, monitoring data from the Delaware River show that
the minimum percent oxygen saturation in each year is closely related
to the 10th percentile. Based on a linear regression of 2002-2022 data
from the monitoring stations at Chester and Penn's Landing, the EPA
expects that when the 10th percentile of daily average oxygen
saturation in the Juvenile Development season is 66%, the minimum daily
average oxygen saturation will be 61% (r\2\ = 0.93, 95% confidence
interval: 60.6% to 61.7% saturation). Based on the EPA's cohort
modeling approach, if the 10th percentile criterion is attained, then
the oxygen values expected to occur during the 12 days of potential
exceedance will not be low enough to result in seasonal HSI values less
than zero or prevent attainment of the propagation use, making the
addition of an instantaneous minimum criterion unnecessary. The EPA
also concluded that the 10th percentile dissolved oxygen condition can
be calculated with greater statistical certainty than the instantaneous
minimum because, by definition, no dissolved oxygen data points are
less than the minimum. In contrast, dissolved oxygen data points are
present both below and above the 10th percentile, providing ample data
to increase the statistical confidence in estimates of the 10th
percentile. Using a more statistically robust criterion like a 10th
percentile compared to an instantaneous minimum criterion will ensure
more predictable water quality assessments, thus reducing the need for
states to account for uncertainty and variability when assessing
attainment of the EPA's criteria. Given issues with variability,
representativeness, and measurement uncertainty associated with
assessment of an instantaneous minimum value, many states add an extra
layer of allowable exceedance frequency to their assessment protocols
for such criteria (e.g., 10% exceedance). The rationale for considering
additional exceedance frequencies is eliminated when setting criteria
at the 10th percentile and median values, as the EPA has done in this
final rule.
In addition to the above stated considerations about why an
instantaneous minimum criterion is not the best approach to protect the
propagation use, the EPA considered if the Agency should include an
instantaneous minimum criterion of 6 mg/L, as suggested by a commenter.
However, the commenter did not provide a sound scientific rationale for
this value, and the EPA's own evaluation does not support the need for
a 6 mg/L instantaneous minimum criterion to protect the propagation
use. Rather, the EPA's evaluation suggested that a defensible value for
an instantaneous minimum would be below 6 mg/L, were the EPA to
calculate an instantaneous minimum criterion to protect the propagation
use. Therefore, the EPA concluded that finalizing a 10th percentile
daily average criterion, and not including an instantaneous minimum
criterion, reflects the latest scientific knowledge and is an
appropriate way to ensure that aquatic life propagation is protected
based on current data.
Several commenters asserted that the EPA's criteria are too
stringent. Some commenters stated that the criteria in the EPA's rule
are higher than criteria for some other waters with designated uses
that include propagation, including surrounding areas of the Delaware
River. Some commenters asserted that the EPA's criteria are too
stringent because Atlantic Sturgeon propagation is already occurring in
the Delaware River and that existing dissolved oxygen levels do not
appear to be adversely affecting sturgeon. Some of these commenters
recommended that the EPA promulgate dissolved oxygen criteria of 4.5
mg/L at a 10% exceedance frequency and 5.0 mg/L at a 50% exceedance
frequency for the Juvenile Development season.
The EPA disagrees that the criteria in this final rule are more
stringent than the dissolved oxygen criteria for surrounding areas of
the Delaware River or other waters cited by commenters with designated
uses that include propagation, such as the Chesapeake Bay. Upstream
Zone 2 and downstream Zone 6 of the Delaware River have daily average
dissolved oxygen criteria in the summer months (June 16 to September
15) of 5 mg/L and 6 mg/L, respectively. Because these criteria in Zones
2 and 6 have comparable magnitudes and no exceedance frequency, they
are more
[[Page 46494]]
stringent than the EPA's final dissolved oxygen criteria for the
Juvenile Development season. Please refer to the associated response to
comments document for more discussion about the comparison between the
criteria in this final rule with dissolved oxygen criteria for some
other waters along the East Coast, such as the Chesapeake Bay.
Commenters recommending the EPA adopt dissolved oxygen criteria of
4.5 mg/L at a 10% exceedance frequency and 5.0 mg/L at a 50% exceedance
frequency for the Juvenile Development season did not provide a sound
scientific rationale as to how these values would be protective of the
propagation designated use, in accordance with 40 CFR 131.11(a). A
dissolved oxygen criterion of 4.5 mg/L generally reflects current
conditions in the specified zones. Under current conditions,
propagation of oxygen-sensitive species has been ``weak and
inconsistent'' according to the DRBC \88\ and the New York Bight DPS of
Atlantic Sturgeon remains at a high risk of extinction according to
NMFS.\89\ Please refer to the associated response to comments document
for more discussion about Atlantic Sturgeon propagation under current
conditions in the specified zones.
---------------------------------------------------------------------------
\88\ ``Weak and inconsistent spawning by Atlantic Sturgeon and
limited spatial recovery in spawning and rearing by American Shad
and Striped Bass suggested that full restoration of the
``propagation'' use is not supported by the current available
data.'' Delaware River Basin Commission. (2015).
\89\ In their Biological Opinion, NMFS explained that, ``[t]he
New York Bight DPS's risk of extinction is ``High'' due to low
productivity (e.g., relatively few adults compared to historical
levels and irregular spawning success), low abundance (e.g., only
three known spawning populations and low DPS abundance, overall),
and limited spatial distribution (e.g., limited spawning habitat
within each of the few known rivers that support spawning).''
Documents associated with Endangered Species Act consultation,
including the Biological Opinion, are available in the docket for
this rule.
---------------------------------------------------------------------------
Criteria Development for Spawning and Larval Development and
Overwintering Seasons
The Atlantic Sturgeon cohort model described above relies on
experimental studies that were conducted using juvenile sturgeon and
therefore provides information that is most relevant to juvenile growth
and survival.\90\ Additionally, the underlying studies allocated most
experimental treatments to water temperatures between 12 [deg]C and 28
[deg]C, with a single experimental treatment at 6 [deg]C and none at
lower water temperatures.\91\ The EPA's cohort modeling approach
therefore does not apply to the Spawning and Larval Development season
and is not well-constrained by data for application to the
Overwintering season. For example, overwintering juveniles experience
lower water temperatures for longer periods than juvenile Atlantic
Sturgeon experienced in available experimental studies. Causes of
overwintering mortality, which do not include low oxygen, are not
addressed. While juveniles are present during the spawning and larval
development period, they are from the prior season and are larger than
fish whose oxygen sensitivity has been studied. Accordingly, the EPA
did not use the cohort model to derive criteria for the Spawning and
Larval Development or Overwintering seasons.
---------------------------------------------------------------------------
\90\ Experimental data are from Campbell and Goodman 2004 and
Niklitschek and Secor 2009a.
\91\ Niklitschek and Secor 2009a.
---------------------------------------------------------------------------
Instead, the EPA reviewed available literature and concluded that
Atlantic Sturgeon larvae were likely to be at least as sensitive to low
dissolved oxygen as juvenile Atlantic Sturgeon \92\ and that
overwintering juveniles have temperature-limited metabolism and
therefore have similar or slightly lower oxygen requirements than
juveniles in warmer waters (e.g., summer water temperatures).\93\ Thus,
the EPA determined that the percent oxygen saturation threshold that
would be protective of juveniles experiencing stressful (high) water
temperatures during the Juvenile Development season would also be
protective of larvae and overwintering juveniles not experiencing high
water temperatures. Therefore, the EPA is finalizing criteria requiring
the 10th percentile of daily average oxygen saturation to be at least
66% during the Spawning and Larval Development and Overwintering
seasons. From 2002-2022, typical oxygen levels during the Spawning and
Larval Development and Overwintering seasons were well above the level
expected to negatively impact either Atlantic Sturgeon or other oxygen-
sensitive species. Therefore, the EPA concluded that a second criterion
at the 50th percentile of daily average oxygen was not needed during
these seasons.
---------------------------------------------------------------------------
\92\ Stoklosa et al. (2018); United States Environmental
Protection Agency. (2000). Ambient Aquatic Life Water Quality
Criteria for Dissolved Oxygen (Saltwater): Cape Cod to Cape
Hatteras. Document ID: EPA-822-R-00-012. November 2000. https://www.epa.gov/sites/default/files/2018-10/documents/ambient-al-wqc-dissolved-oxygen-cape-code.pdf.
\93\ Niklitschek and Secor (2009a, 2009b).
---------------------------------------------------------------------------
Criteria Expressed as Percent Oxygen Saturation
Finally, the EPA proposed and is finalizing criteria derived in
terms of percent oxygen saturation in this instance, rather than in
units of concentration (such as milligrams per liter or mg/L) for two
related reasons.\94\ Most importantly, percent oxygen saturation
determines the maximum rate at which aquatic organisms can absorb
oxygen from the water and therefore, is the measurement of oxygen level
that most directly relates to growth and survival of aquatic
organisms.\95\ If the maximum rate at which an aquatic organism can
absorb oxygen from the water is less than needed to meet basic
metabolic requirements, the organism is at increased risk of mortality.
Because organisms require an increased rate of oxygen supply to obtain
and digest food, a reduced rate of oxygen supply may also cause reduced
growth, even if it does not cause mortality. Although dissolved oxygen
concentration is related to percent oxygen saturation, it also varies
in relation to water temperature and, to a lesser extent, in relation
to salinity, which together determine oxygen concentration at
equilibrium with the atmosphere. For any level of oxygen saturation,
dissolved oxygen concentration will be relatively low when water
temperature and salinity are high, and relatively high when water
temperature and salinity are low. Therefore, protective dissolved
oxygen concentrations vary with water temperature, as is reflected in
the seasonally varying concentration-based criteria for the specified
zones of the Delaware River that the EPA sought public comment on in
the proposed rule as an alternative to the proposed percent saturation
criteria. The effect of temperature is especially challenging for
deriving protective concentration-based criteria for periods within
which water temperature varies substantially. Given the relationship
between water temperature and dissolved oxygen concentration, criteria
expressed as a concentration could be either higher than needed to
protect the use or not high enough to protect the use, depending on
water temperature. Conversely, the EPA's criteria for the 10th
percentile do not vary seasonally, despite substantial seasonal
differences in water temperature. Therefore, criteria expressed as
percent oxygen saturation
[[Page 46495]]
provide more consistent protection of aquatic life across seasonally
changing water temperatures and provide a more direct scientific
rationale linking oxygen levels and aquatic life use protection. A
summary of comments the EPA received on the expression of criteria in
percent oxygen saturation is available below in section III.C.3. of
this preamble.
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\94\ Percent oxygen saturation and dissolved oxygen
concentration are two different ways to measure oxygen levels in
water. Dissolved oxygen concentration is the amount of oxygen
dissolved in the water, typically represented as milligrams of
oxygen per liter of water. Percent oxygen saturation is the ratio,
expressed as a percentage, of the dissolved oxygen concentration in
the water relative to the dissolved oxygen concentration when at
equilibrium with the atmosphere (i.e., if there were nothing in the
water producing or consuming oxygen).
\95\ Niklitschek and Secor (2009a).
---------------------------------------------------------------------------
2. Final Dissolved Oxygen Criteria
The EPA is finalizing the dissolved oxygen criteria as proposed,
with only one non-substantive textual change to the language describing
the criteria exceedance frequencies for clarity.\96\
---------------------------------------------------------------------------
\96\ United States Environmental Protection Agency. (2023).
Water Quality Standards to Protect Aquatic Life in the Delaware
River. Proposed Rule. 88 FR 88315. December 21, 2023.
---------------------------------------------------------------------------
The EPA's dissolved oxygen criteria cover three distinct seasons
and are intended to protect oxygen-sensitive species in the Delaware
River, as explained above. The Spawning and Larval Development season
is March 1 to June 30 and captures a comprehensive range of resident
aquatic species' spawning periods.\97\ The Juvenile Development season
is July 1 to October 31 and captures critical early growth and
development for young-of-the-year Atlantic Sturgeon. The Overwintering
season is November 1 to February 28 (or 29, in a leap year), when
juvenile Atlantic Sturgeon growth is limited by low water temperatures.
---------------------------------------------------------------------------
\97\ Stoklosa et al. (2018); Delaware River Basin Commission
(2015).
---------------------------------------------------------------------------
Each season has water quality criteria that consist of three
components: magnitude, duration, and exceedance frequency. The
magnitude component indicates the required level of dissolved oxygen in
the water, which in this rule is expressed as percent oxygen
saturation. The duration component specifies the time period over which
water quality is averaged before it can be compared with the criteria
magnitude; in this rule, the duration is a daily average. The EPA
selected a daily average duration because it is readily measurable
using dissolved oxygen sensors and is protective in the relevant zones
of the Delaware River because variations at time scales of less than
one day are relatively small. Additionally, while the available science
for Atlantic Sturgeon does not address the effect of low oxygen
exposures lasting less than one day, calculations outlined in the
Virginian Province Document suggest that to cause high mortality within
a few hours, daily minimum oxygen concentrations would have to be lower
than the minimum oxygen levels that the EPA expects would be likely in
the specified zones if the EPA's criteria are attained.\98\ The
exceedance frequency component specifies how often each criterion
magnitude can be exceeded while still ensuring that the use is
protected. For this rulemaking, the exceedance frequency was determined
based on the percentile of percent oxygen saturation from which the
magnitude is derived. For example, the 10th percentile criterion
magnitude can be exceeded on 10% of days in the season, which for a
season consisting of 123 days is no more than 12 cumulative days of
exceedance. For dissolved oxygen, an exceedance occurs when the daily
average oxygen level in the water is below the criterion magnitude.
---------------------------------------------------------------------------
\98\ United States Environmental Protection Agency. (2000).
Ambient Aquatic Life Water Quality Criteria for Dissolved Oxygen
(Saltwater): Cape Cod to Cape Hatteras. Document ID: EPA-822-R-00-
012. November 2000. https://www.epa.gov/sites/default/files/2018-10/documents/ambient-al-wqc-dissolved-oxygen-cape-code.pdf.
---------------------------------------------------------------------------
In this final rule, the Spawning and Larval Development and
Overwintering seasons each have a single, identical dissolved oxygen
criterion with a magnitude of 66% oxygen saturation, a daily average
duration, and an exceedance frequency that allows for up to 12 days of
cumulative exceedance during each of these two seasons (i.e., 10% of
each 123-day season) (table 6 of this preamble). The Juvenile
Development season has two individually applicable dissolved oxygen
criteria that together define a protective seasonal distribution of
percent oxygen saturation. The criteria differ in both magnitude and
exceedance frequency and both levels must be attained. The first
Juvenile Development criterion defines the lower end of the
distribution of oxygen levels and consists of a magnitude of 66% oxygen
saturation, a daily average duration, and an exceedance frequency that
allows for up to 12 days of cumulative exceedance during the season
(i.e., 10% of the 123-day season). The second Juvenile Development
criterion defines the center of the distribution of oxygen levels and
consists of a magnitude of 74% oxygen saturation, a daily average
duration, and an exceedance frequency that allows for up to 61 days of
cumulative exceedance during the season (i.e., 50% of the 123-day
season) (table 6 of this preamble).
The dissolved oxygen criteria in this final rule are the same as
the criteria that the EPA proposed, with one non-substantive textual
change for clarity.\99\ The EPA altered the expression of the criteria
exceedance frequency, as reflected in the rightmost column in table 6
of this preamble and in the final regulatory text. Whereas the EPA
proposed exceedance frequencies expressed as, for example, ``10% (12
Days Cumulative),'' for the final rule, the EPA reversed the order
(e.g., ``12 Days Cumulative (10% of the 123-day season)'') to make
clear that assessment in each season is based on the entire season and
not the number of measurements collected.
---------------------------------------------------------------------------
\99\ United States Environmental Protection Agency. (2023).
Water Quality Standards to Protect Aquatic Life in the Delaware
River. Proposed Rule. 88 FR 88315. December 21, 2023.
Table 6--Final Dissolved Oxygen Criteria
----------------------------------------------------------------------------------------------------------------
Magnitude
Season (percent oxygen Duration Exceedance frequency
saturation)
----------------------------------------------------------------------------------------------------------------
Spawning and Larval Development 66 Daily Average.................. 12 Days Cumulative
(March 1-June 30). (10% of the 123-day
season).
Juvenile Development (July 1-October 66 Daily Average.................. 12 Days Cumulative
31). (10% of the 123-day
season).
74 Daily Average.................. 61 Days Cumulative
(50% of the 123-day
season).
Overwintering (November 1-February 66 Daily Average.................. 12 Days Cumulative
28/29). (10% of the 123-day
season).
----------------------------------------------------------------------------------------------------------------
[[Page 46496]]
3. Comments Received on Criteria Alternatives Presented at Proposal
At proposal, the EPA included three alternative options for
dissolved oxygen criteria that the Agency considered but ultimately did
not propose due to concerns about whether each alternative would be
protective of aquatic life propagation. The EPA requested comment and
additional information on whether and how one or more of these
alternatives could protect the proposed aquatic life designated uses in
the specified zones of the Delaware River and if so, what anticipated
benefits would be associated with the alternative compared to the EPA's
proposed criteria. This section provides summaries of the comments
received regarding the three criteria alternatives and summaries of the
EPA's responses.
Alternative 1: Dissolved Oxygen Criteria Expressed as Concentration
(mg/L)
For the reasons described above in section III.C. of this preamble,
the EPA proposed dissolved oxygen criteria expressed as percent oxygen
saturation. For the first alternative, the EPA provided an example of
potential criteria expressed as concentration (mg/L) and requested
comment on whether criteria expressed as concentration would be
protective of oxygen-sensitive species during each season. The EPA also
requested public input and supporting information about other ways the
Agency could develop dissolved oxygen criteria expressed as
concentration--particularly for the Spawning and Larval Development and
Overwintering seasons--to protect the relevant aquatic life uses in
accordance with the CWA.
Most commenters indicated a preference for criteria expressed as
concentration due to concerns regarding implementation, specifically
NPDES permitting, and ease of public communication. In addition, some
commenters asserted that criteria expressed as concentration are more
protective of aquatic life, especially in warmer water temperatures.
Conversely, commenters supporting criteria expressed as percent oxygen
saturation agreed with the EPA's rationale as presented in the
associated technical support document and summarized in section
III.C.2. of this preamble. In addition to public comments, the EPA also
solicited comment on this alternative from external peer reviewers.
External peer reviewers supported the criteria expressed as percent
oxygen saturation, rather than concentration, as percent oxygen
saturation is the measurement of oxygen level that most directly
relates to growth and survival of aquatic organisms.
The EPA understands that the switch from concentration-based
dissolved oxygen criteria to percent saturation because of this rule
could require changes to each state's NPDES permitting procedures and
could necessitate additional public education and outreach. However,
the EPA is committed to working with Delaware, New Jersey,
Pennsylvania, and the DRBC to address implementation and outreach
concerns and provide technical support. To inform the Agency's
consideration of this alternative for the final rule, the EPA met with
the DRBC, Delaware, New Jersey, and Pennsylvania to discuss the percent
oxygen saturation aspect of the proposal and potential solutions to
implementation challenges and ways in which the EPA could assist in a
transition to percent oxygen saturation for NPDES permits.
The EPA disagrees with commenters' assertions that criteria
expressed as concentration are more protective of aquatic life than
criteria expressed as percent oxygen saturation. The EPA derived
equally protective values expressed as concentration and percent oxygen
saturation for the Juvenile Development season using the Atlantic
Sturgeon cohort model. For informational purposes, the EPA is providing
the corresponding values in concentration for the Juvenile Development
season in table 7 of this preamble.
Table 7--Corresponding Dissolved Oxygen Values in Concentration for the Juvenile Development Season
----------------------------------------------------------------------------------------------------------------
Season Magnitude (mg/L) Duration Exceedance frequency
----------------------------------------------------------------------------------------------------------------
Juvenile Development (July 1-October 5.4 Daily Average.................. 12 Days Cumulative
31). (10% of the 123-day
season).
6.1 Daily Average.................. 61 Days Cumulative
(50% of the 123-day
season).
----------------------------------------------------------------------------------------------------------------
For the Spawning and Larval Development and Overwintering seasons,
the EPA requested, but did not receive, information and methods for
deriving protective concentration-based criteria in those seasons.\100\
In the absence of such information, the EPA could not derive protective
concentration-based criteria for the Spawning and Larval Development
and Overwintering seasons. Instead, the Agency is finalizing criteria
for each of the seasons expressed as percent saturation for the reasons
explained in section III.C.1 of this preamble. Monitoring data from the
last decade indicate that the EPA's percent saturation-based dissolved
oxygen criteria for the Spawning and Larval Development and
Overwintering seasons are being attained in the specified zones of the
Delaware River, and therefore the EPA does not anticipate
implementation of the criteria in these seasons to require additional
pollutant controls from any regulated entities. Nonetheless, given that
some commenters expressed greater familiarity with dissolved oxygen
criteria expressed as concentration, for informational purposes,
transparency, and completeness, the EPA is reproducing in table 8 of
this preamble the concentration-based dissolved oxygen values for the
Spawning and Larval Development and Overwintering seasons that the
Agency took comment on in the proposed rule.\101\ As noted in the
preamble to the proposed rule, the EPA calculated alternative
concentration-based dissolved oxygen values for the Spawning and Larval
Development and Overwintering seasons that differed based on water
temperature assumptions and noted concerns about whether these
alternative values would be protective in these seasons when
temperatures are cooler.\102\ As one option, the EPA used the 90th
percentile of water temperatures in each season to convert the proposed
66% oxygen saturation criterion to a concentration, and as a second
option, the EPA used the average water temperature in each
[[Page 46497]]
season.\103\ Unlike the equally protective concentration-based values
for the Juvenile Development season that the EPA derived using the
Atlantic Sturgeon cohort model and is providing for illustrative
purposes in table 7 of this preamble, the EPA reiterates that the
values in table 8 of this preamble should not be viewed as necessarily
protective of the aquatic life designated use that the EPA is
promulgating in this final rule. Rather, these values in table 8 of
this preamble are simply an illustrative conversion of the protective
percent saturation criteria for the Spawning and Larval Development and
Overwintering seasons using specific temperature assumptions. The
concentration-based values provided in tables 7 and 8 for informational
purposes are not being promulgated as criteria in this final rule.
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\100\ United States Environmental Protection Agency. Proposed
Rule: Water Quality Standards to Protect Aquatic Life in the
Delaware River. 88 FR 88315. December 21, 2023.
\101\ Ibid.
\102\ Ibid.
\103\ Seasonal 90th percentile and mean water temperature were
calculated using the daily climatology computed for Chester for
March 1, 2012-June 30, 2022, for the Spawning and Larval Development
season and November 1, 2011-February 28, 2022, for the Overwintering
season.
Table 8--Illustrative Example Dissolved Oxygen Values in Concentration
for the Spawning and Larval Development and Overwintering Seasons
------------------------------------------------------------------------
Water temperature
Season ([deg]C) Magnitude (mg/L)
------------------------------------------------------------------------
Spawning and Larval Development * 23.3 (14.7) * 5.6 (6.7)
(March 1-June 30)..............
Overwintering (November 1- * 12.4 (5.6) * 7.0 (8.3)
February 28/29)................
------------------------------------------------------------------------
\*\ The 90th percentile of seasonal water temperature and corresponding
value is used for the main estimate, while the average water
temperature and corresponding value is shown in parentheses.
One commenter suggested that concentration-based criteria
calculated for critical conditions (examples provided were low flow
conditions or high temperatures) could be applied year-round. However,
given the negative relationship between dissolved oxygen concentrations
and temperature, as explained previously in section III.C.1. of this
preamble, year-round concentration-based criteria calculated using
summer high temperatures may not be protective at lower temperatures.
The EPA recognizes that criteria expressed as concentration would
become more stringent if water temperatures increase; however, the
EPA's criteria are derived to protect aquatic life designated uses that
include propagation in the specified zones of the Delaware River based
on current water quality data. As explained in section II of this
preamble, states are required to review their WQS at least once every
three years and if appropriate, revise or adopt new standards. The
EPA's technical approach for this rulemaking illustrates one potential
way in which new water quality data could be evaluated to determine if
a change to criteria is needed to maintain protectiveness. Thus, the
EPA anticipates that Delaware, New Jersey, and Pennsylvania will
reexamine the applicable aquatic life uses and dissolved oxygen
criteria promulgated in this rule when completing their triennial
reviews and determine if revised criteria are necessary to comply with
the CWA. During their triennial review, states may also consider making
other revisions to their applicable WQS.
For all these reasons, the EPA has concluded that criteria
expressed as percent oxygen saturation are protective and consistent
with the latest science and therefore, the Agency did not move forward
with this alternative for the final rule.
Alternative 2: Single Dissolved Oxygen Criterion During the Juvenile
Development Season With a 10% Exceedance Frequency
The EPA proposed dissolved oxygen criteria for the Juvenile
Development season that consisted of two values that would both have to
be met during the season. For the second alternative, the EPA requested
comment and supporting information on instead applying a single daily
average dissolved oxygen criterion with an exceedance frequency of 10%
of days during the Juvenile Development season.
Some commenters preferred the single criterion construct, with one
commenter asserting that the EPA's methodology provides a stronger
technical basis for a single criterion. Other commenters did not
support Alternative 2, with one commenter expressing a preference for a
single instantaneous minimum criterion, and another supporting lower
criteria magnitudes expressed as concentration.
The EPA's responses to comments regarding an instantaneous minimum
criterion and criteria expressed as concentration are articulated above
in this section of this preamble. The EPA disagrees that there is a
stronger technical basis for a single criterion construct. As explained
above, the dual criteria construct is intended to ensure that oxygen
levels throughout the critical Juvenile Development season consistently
support aquatic life propagation. Therefore, the Agency did not move
forward with this alternative for the final rule.
Alternative 3: Inclusion of a 1-in-3-Year Interannual Exceedance
Frequency
The EPA proposed criteria that must be met every year. For the
third alternative, the EPA requested comment and supporting information
on the addition of a 1-in-3-year interannual exceedance frequency as
part of the dissolved oxygen criteria, and specifically how and why
this approach would protect the applicable aquatic life uses.
Most commenters did not support the inclusion of an interannual
exceedance frequency. These commenters noted that due to the small
population size of Atlantic Sturgeon in the Delaware River, combined
with the interannual variability in the number of spawning adults, even
one year with a criteria exceedance could reduce the ability of
sturgeon to propagate and be detrimental to the year class. Some
commenters expressed support for inclusion of an interannual exceedance
frequency. These commenters preferred this alternative to address
uncertainty in the EPA's criteria derivation methods for this
rulemaking and dissolved oxygen variability caused by factors such as
drought or low flow. In addition to public comments, the EPA also
solicited comment on this alternative from external peer reviewers.
External peer reviewers did not support the inclusion of a 1-in-3-year
interannual exceedance frequency. One reviewer noted that the effect of
a failed year class resulting from poor water quality could impact the
population for many years. This reflects the fact that Atlantic
Sturgeon often have a long lifespan, with consistently low rates of
mortality as adults. In contrast, mortality is highest among young-of-
the-year juveniles and has the most potential to
[[Page 46498]]
be reduced; therefore, reduction in juvenile mortality can have the
greatest impact on population growth.\104\ If recruitment is low in a
year due to high juvenile mortality, a demographic gap can persist in
the adult population for several decades, potentially reducing the
number of adults returning to spawn. Overall, reviewers noted that
uncertainties around this alternative are significantly higher and that
it is a less biologically relevant option.
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\104\ Gross, M.R., J. Repka, C.T. Robertson, D. Secor and W. Van
Winkle (2002). Sturgeon Conservation: Insights from Elasticity
Analysis. American Fisheries Society Symposium 28: 13-30.
---------------------------------------------------------------------------
As described above, the EPA specifically requested comment on
whether and how this alternative would protect aquatic life
propagation. Commenters who supported this alternative did not provide
such supporting information. Therefore, the EPA did not have sufficient
information to conclude that this alternative would protect designated
uses that include aquatic life propagation. The EPA agrees with
commenters and peer reviewers that allowing one year of exceedance
could have detrimental impacts on sturgeon propagation, which in turn
could impact the population for decades. Therefore, the EPA did not
move forward with this alternative for the final rule.
IV. Endangered Species Act Consultation
Section 7(a)(2) of the Endangered Species Act (ESA) requires that
each Federal agency ensure that any action authorized, funded, or
carried out by such agency is not likely to jeopardize the continued
existence of any endangered or threatened species or result in the
destruction or adverse modification of critical habitat.\105\ Pursuant
to section 7(a)(2) of the ESA, and prior to finalizing this rulemaking,
the EPA consulted with the U.S. Fish and Wildlife Service (FWS) and
NMFS (collectively, ``the Services'') on the WQS the EPA is
promulgating in this final rule. For species in the action area that
are under the jurisdiction of the FWS,\106\ on April 4, 2024, the FWS
concurred with the EPA's determination that the EPA's action is not
likely to have an adverse effect on those listed species.\107\ NMFS
determined in a final Biological Opinion dated October 11, 2024,\108\
that the EPA's action is not likely to adversely affect certain species
and critical habitat in the action area,\109\ and is likely to
adversely affect certain other species but will not jeopardize their
continued existence or destroy or adversely modify their designated
critical habitat.\110\ NMFS concluded that ``the EPA set the [dissolved
oxygen] criteria at levels expected to allow for the successful
propagation of [S]hortnose and New York Bight DPS of Atlantic
[S]turgeon, improving prospects for increasing population sizes for
both species spawning in the river.'' Documents associated with ESA
consultation are available in the docket for this rule.
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\105\ 16 U.S.C. 1536(a)(2).
\106\ These species include three mammals (Indiana Bat, Northern
Long-eared Bat, and Tricolored Bat), one bird (Rufa Red Knot), one
reptile (Bog Turtle), one insect (Monarch Butterfly), and two
flowering plants (Sensitive-joint Vetch and Swamp Pink).
\107\ United States Fish and Wildlife Service. (2024). Letter to
Gregory Voigt. Reference: Biological Evaluation for the
Establishment of the Aquatic Life Propagation Designated Use and
Dissolved Oxygen Criteria for the Delaware River, States of New
Jersey, Pennsylvania, and Delaware. Document ID 2024-0046899. April
4, 2024.
\108\ National Marine Fisheries Service. Establishment of
Aquatic Life Propagation Designated Use and Dissolved Oxygen
Criteria for the Delaware River by the United States Environmental
Protection Agency. Endangered Species Act Section 7 Biological
Opinion. OPR-2022-03643. National Oceanic and Atmospheric
Administration. October 11, 2024. https://doi.org/10.25923/jqht-ke64.
\109\ These species and critical habitat include two mammals
(Fin Whale and North Atlantic Right Whale), five reptiles (Green Sea
Turtle, Kemp's Ridley Sea Turtle, Leatherback Sea Turtle, Hawksbill
Sea Turtle, Loggerhead Sea Turtle), Atlantic Sturgeon Distinct
Population Segments (DPSs) that do not spawn in the Delaware River
(i.e., Gulf of Maine, Chesapeake Bay, Carolina, and South Atlantic
DPSs), and designated critical habitat for the New York Bight DPS of
Atlantic Sturgeon.
\110\ These species are the Shortnose Sturgeon and the New York
Bight DPS of Atlantic Sturgeon.
---------------------------------------------------------------------------
NMFS included an Incidental Take Statement (ITS) in its Biological
Opinion to address the incidental take of Shortnose Sturgeon and
Atlantic Sturgeon in the Delaware River due to exposure to dissolved
oxygen levels in waters that attain the EPA's final criteria. The ESA
and its implementing regulations provide that incidental take by a
Federal agency is not prohibited if performed in compliance with the
terms and conditions of an ITS.\111\ The ITS included two Reasonable
and Prudent Measures (RPMs) NMFS considered necessary and appropriate
for the EPA to follow to minimize the effects of incidental take on
Shortnose Sturgeon and Atlantic Sturgeon:\112\
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\111\ 16 U.S.C. 1536(b)(4), (o)(2); 50 CFR 402.14(i)(6).
\112\ The EPA does not necessarily endorse or concede that these
RPMs are necessary or appropriate to minimize the impact of any
incidental take.
---------------------------------------------------------------------------
1. EPA is to work within its authorities to ensure that its final
dissolved oxygen criteria are implemented in a timely manner to
minimize the aggregate adverse effects to ESA-listed Shortnose Sturgeon
and New York Bight DPS of Atlantic Sturgeon and critical habitat
designated for the New York Bight DPS of Atlantic Sturgeon specifically
within the Delaware River.
2. EPA is to work within its authorities to oversee the
implementation of the dissolved oxygen criteria, coordinating with the
Services and encouraging other entities to coordinate with the
Services, as appropriate.
NMFS specified in the Terms and Conditions of the ITS that to meet
the first RPM, the EPA is to notify regulatory agencies and the
regulated community that, in NMFS's view as of October 2024, existing
dissolved oxygen conditions in the Delaware River violate the ESA by
resulting in the take of endangered Shortnose Sturgeon and the New York
Bight DPS of Atlantic Sturgeon through increased mortality and
reductions in growth of juvenile fish. Per the ITS, the EPA is to
reference the following sections of the ESA and its implementing
regulations. Section 9 of the ESA \113\ prohibits the ``take'' of
endangered species by any person, defined by the ESA.\114\ The ESA
defines ``take'' as ``to harass, harm, pursue, hunt, shoot, wound,
kill, trap, capture, or collect, or to attempt to engage in any such
conduct.'' \115\ The terms ``harass'' and ``harm'' are currently
further defined in NMFS guidance \116\ and in regulation,\117\
respectively. Entities that are discharging in accordance with limits
based on the EPA's final criteria are covered by the ITS exemption in
the Biological Opinion; entities that are not discharging in accordance
with such limits may elect to seek separate incidental take coverage
under section 10 of the ESA. For more information, see NMFS's ESA
section 7 Biological Opinion, available in the docket for this rule.
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\113\ 16 U.S.C. 1538.
\114\ 16 U.S.C. 1532(13). NMFS also specified in the Terms and
Conditions that the EPA is to reference ESA section 11, which
authorizes criminal and civil penalties for violations of the take
prohibition. 16 U.S.C. 1540.
\115\ 16 U.S.C. 1532(19).
\116\ NMFS Policy Directive 02-110-19.
\117\ 50 CFR 222.102. On April 17, 2025, the Services proposed a
rule to rescind the regulatory definition of ``harm'' in the ESA
implementing regulations. Rescinding the Definition of ``Harm''
Under the Endangered Species Act, 90 FR 161102 (April 17, 2025).
---------------------------------------------------------------------------
Additionally, to meet the first RPM, the EPA is to remind
regulatory agencies, the regulated community, and the interested public
of the EPA's authorities under the CWA that are potentially relevant to
this final rule. These authorities include reviewing
[[Page 46499]]
TMDLs pursuant to CWA section 303(d); objecting to certain state-issued
CWA section 402 pollutant discharge permits under CWA section
402(d)(2); issuing CWA section 402 pollutant discharge permits under
CWA section 402(d)(4) if the EPA's objections to state-issued permits
are not adequately addressed; or withdrawing state pollutant discharge
permitting programs in certain circumstances under CWA section
402(c)(3).
V. Applicability
The EPA is promulgating a Federal designated use that applies in
New Jersey and Pennsylvania, in addition to those states' designated
uses that are already applicable. This means that for the specified
zones of the Delaware River, the EPA is supplementing, rather than
replacing, New Jersey's and Pennsylvania's currently applicable aquatic
life designated uses. Therefore, New Jersey's and Pennsylvania's
currently applicable aquatic life designated uses remain applicable for
CWA purposes. Those states' current water quality criteria associated
with those uses also remain applicable for CWA purposes, with the
exception of any aquatic life criteria for dissolved oxygen, which are
discussed below. The EPA concluded that this approach is the best way
to make clear which of the states' WQS are and are not revised by this
final rule.
In addition, the EPA is promulgating dissolved oxygen criteria that
replace Delaware's, New Jersey's, and Pennsylvania's existing dissolved
oxygen criteria for the specified zones of the Delaware River. In the
final rule, the EPA made a minor, non-substantive change to paragraph
(d)(2) to simplify the language used to describe the other state water
quality criteria that apply to these zones of the Delaware River in
addition to the federally promulgated criteria for dissolved oxygen.
Specifically, the EPA replaced the language ``with applicable water
quality criteria for other parameters'' with ``with other applicable
water quality criteria.'' One commenter shared that Delaware's
regulations specify that the applicable criteria for the specified
zones of the Delaware River are those adopted by the DRBC in its Water
Quality Regulations, unless no criteria exist in the DRBC's regulations
in which case the state's criteria apply. This commenter asserted that
the proposed rule did not define how the proposed designated use and
criteria will be adopted into the DRBC's Water Quality Regulations. The
designated use and dissolved oxygen criteria in this final rule do not
need to be adopted into the DRBC's Water Quality Regulations in order
to apply to these zones of the Delaware River. Pursuant to 40 CFR
131.21, where a WQS in effect under state law is applicable for CWA
purposes, if the EPA promulgates a more stringent standard for that
state, then the EPA-promulgated standard becomes the applicable
standard for CWA purposes. Further, under CWA section 303(c)(4)(B), the
EPA Administrator has the authority to promulgate standards in any case
where the Administrator determines that a new or revised standard is
necessary to meet the requirements of the CWA, as discussed more in
section II.A of this preamble. Pursuant to CWA section 303(c), the
Agency made an Administrator's Determination and is promulgating
Federal WQS for Delaware, New Jersey, and Pennsylvania in accordance
with that Administrator's Determination. As such, the WQS in this final
rule will be effective for CWA purposes even though they have not been
adopted by the DRBC.
The EPA recognizes, however, that with this final rule, there will
now be a mix of state and Federal WQS that are applicable to the
specified zones for CWA purposes. The EPA compiles and publishes on its
website \118\ the state-adopted and federally promulgated WQS in effect
for CWA purposes in each state, including the Federal CWA-effective WQS
for the specified zones covered by this rule. For transparency and ease
of implementation, the EPA recommends that Delaware, New Jersey, and
Pennsylvania similarly identify in a publicly available place that the
WQS in the EPA's final rule are part of the CWA-effective WQS in each
state (e.g., by including a notation in each state's WQS and/or on the
website that hosts each state's WQS, directing people to the Federal
Register publication for this final rule, appropriate section of 40 CFR
part 131, and/or the EPA's website).
---------------------------------------------------------------------------
\118\ United States Environmental Protection Agency. State-
Specific Water Quality Standards Effective under the Clean Water Act
(CWA). https://www.epa.gov/wqs-tech/state-specific-water-quality-standards-effective-under-clean-water-act-cwa. Accessed September
19, 2024.
---------------------------------------------------------------------------
The EPA notes that there are aquatic life criteria for pollutants
and parameters other than dissolved oxygen that are still in effect for
CWA purposes in all three states--not only in the zones covered by this
final rule, but also for other zones of the Delaware River that already
include aquatic life propagation as a designated use. Those criteria
are not impacted by this final rule. As the EPA is only promulgating
revised dissolved oxygen criteria for the specified zones of the
Delaware River, Delaware, New Jersey, and Pennsylvania should evaluate
whether other aquatic life criteria should similarly be added or
revised for the specified zones or other zones of the Delaware River.
One way these states can review their WQS is through the triennial
review process. As explained in section II of this preamble, states
must review their WQS at least once every three years and, if
appropriate, revise standards or adopt new standards (CWA section
303(c)(1) and 40 CFR 131.20(a)). The EPA anticipates that Delaware, New
Jersey, and Pennsylvania will review their existing aquatic life
criteria during their next triennial review to determine if new or
revised aquatic life criteria are appropriate to protect the applicable
aquatic life designated uses, including the designated use that the EPA
is promulgating in this final rule, in addition to considering whether
to make other changes to their WQS.
One commenter asserted that Pennsylvania has a minimum dissolved
oxygen criterion of 5 mg/L that currently applies to the specified
zones of the Delaware River under Pennsylvania's jurisdiction and that
the EPA failed to recognize the application of this criterion. This
commenter asserted that the EPA's proposed dissolved oxygen criteria
would result in a weakening of the applicable WQS because the EPA's
criteria could allow daily excursions down to or below 4 mg/L, and that
this would violate the antidegradation requirement at 40 CFR
131.12(a)(1) to maintain and protect existing uses. Further, this
commenter asserted that the EPA has a duty under the Endangered Species
Act to ensure no jeopardy to the endangered sturgeon in the specified
zones and that the EPA's effort to update the WQS must be consistent
with full recovery of the sturgeon rather than only slight improvements
in their condition, which may be insufficient.
As noted in sections II.D. and III.B. of this preamble,
Pennsylvania's WWF designated use and the EPA-approved aquatic life
criteria associated with Pennsylvania's WWF use, including the state's
WWF dissolved oxygen criteria of 5.5 mg/L as a 7-day average and 5.0
mg/L as a minimum, do not currently apply for CWA purposes to the
specified zones of the Delaware River. For the WWF use and associated
criteria to apply in the relevant zones for CWA purposes, Pennsylvania
would need to revise its WQS accordingly and the EPA would need to
approve that revision under CWA section 303(c). Rather, prior to this
final rule, the applicable aquatic life designated use for
Pennsylvania's portions of the specified zones of the
[[Page 46500]]
Delaware River aligned with the DRBC's ``maintenance'' and ``passage''
designated use and the applicable dissolved oxygen criteria in
Pennsylvania's portions of the relevant zones were the DRBC's criteria
that Pennsylvania had adopted into its WQS by reference--namely, a
year-round numeric water quality criterion for dissolved oxygen of 3.5
mg/L as a 24-hour average, as well as a seasonal criterion of 6.5 mg/L.
Therefore, the EPA's aquatic life designated use of ``protection and
propagation of resident and migratory aquatic life'' and dissolved
oxygen criteria in this final rule represent a strengthening, rather
than a weakening, of the applicable WQS in the relevant zones in
Pennsylvania and are consistent with all 40 CFR part 131 requirements.
For responses to the comments about daily excursions allowed under the
EPA's criteria and the inclusion of an instantaneous minimum criterion
value, please see section III.C. of this final rule preamble. Regarding
the comment about the EPA's obligations under the Endangered Species
Act, please refer to section IV of this preamble.
VI. Conditions Under Which Federal Water Quality Standards Would Be
Withdrawn
Under the CWA, states and authorized tribes have the primary
responsibility in developing and adopting WQS for their navigable
waters (CWA section 303(a) through (c)). Although the EPA is
promulgating a revised aquatic life designated use and protective
dissolved oxygen criteria for the specified zones of the Delaware
River, each state retains the option to adopt and submit to the EPA for
review its own revised designated use and dissolved oxygen criteria
that are consistent with the requirements of the CWA. If Delaware, New
Jersey, and Pennsylvania subsequently adopt and submit revised WQS to
the EPA, and the EPA approves those WQS, then the EPA would undertake a
rulemaking to withdraw the federally promulgated use and/or dissolved
oxygen criteria (40 CFR 131.21(c)). Similarly, if one state adopts and
submits revised WQS to the EPA, and the EPA approves those WQS, then
the EPA would undertake a rulemaking to withdraw the federally
promulgated WQS for that state. As noted earlier in this preamble, the
EPA maintains that states have the primary role to develop WQS.
Pursuant to 40 CFR 131.21(c), if Delaware, New Jersey, and/or
Pennsylvania adopt dissolved oxygen criteria that are as stringent or
more stringent than the federally promulgated criteria, then once the
EPA approves those criteria, they would become the applicable criteria
for CWA purposes.\119\ After approving any state criteria that are as
stringent or more stringent, the EPA would conduct a ministerial
rulemaking to withdraw the Federal criteria. If Delaware's, New
Jersey's, and/or Pennsylvania's adopted dissolved oxygen criteria are
less stringent than the federally promulgated criteria, and the EPA
approves those less stringent criteria, then those EPA-approved
criteria would become the applicable criteria for CWA purposes only
after the EPA withdraws its federally promulgated criteria for the
relevant state(s).
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\119\ CWA section 303(c)(3) (``If the Administrator . . .
determines that such standard meets the requirements of this Act,
such standard shall thereafter be the water quality standard for the
applicable waters of that State.'').
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VII. Alternative Regulatory Approaches and Implementation Mechanisms
In the preamble to the proposed rulemaking, 88 FR 88315, December
21, 2023, the EPA noted several approaches provided at 40 CFR part 131
that Delaware, New Jersey, and Pennsylvania could explore when
implementing or deciding how to implement federally promulgated
criteria. Specifically, the EPA focused the discussion in the proposed
rule preamble on two approaches--WQS variances and NPDES permit
compliance schedules. Additionally, the EPA included a discussion of
CWA section 303(d)/305(b) water quality assessments in the specific
circumstances relevant to this rulemaking. Each of these topics is
discussed in turn directly below.
A. Water Quality Standards Variances and NPDES Permit Compliance
Schedules
With respect to WQS variances and NPDES permit compliance
schedules, some commenters asserted that implementation of the WQS in
the EPA's rule should be phased and adaptively managed with incremental
pollutant reductions followed by monitoring of water chemistry and fish
communities to gauge the effectiveness of the pollutant controls. A few
of these commenters asserted that WQS variances and NPDES permit
compliance schedules are the tools the states should use to allow for
such incremental progress, as needed. Conversely, one commenter
asserted that because propagation is an attainable use in the specified
zones of the Delaware River, WQS variances, which are used when
attaining the designated use and associated criterion is not feasible
during the term of the WQS variance, would defeat the purpose of the
EPA's rule and would inappropriately require subsequent time-consuming
rulemakings by states. Instead, this commenter asserted that NPDES
permit compliance schedules are the appropriate implementation
mechanism to use when dischargers need time to implement additional
treatment technologies.
Regarding the appropriateness of WQS variances to implement the WQS
in this final rule, the commenter is correct that the EPA determined
that the propagation use is attainable in the specified zones. As
discussed in the associated response to comments document, the EPA also
recognizes the comments received on the proposed rule from certain
dischargers regarding potential economic and social impacts. However,
the EPA did not receive information from the states, the DRBC, or other
stakeholders to demonstrate that attaining the propagation use is
infeasible due to one of the factors listed at 40 CFR 131.10(g). Where
a state believes that a discharger may not be able to meet any more
stringent permit limits based on the propagation use and dissolved
oxygen criteria for a specific period of time but can make incremental
water quality improvements towards attaining the propagation use, then
the state should work with the EPA to determine whether a WQS variance
consistent with 40 CFR 131.14 would be appropriate for that discharger.
The EPA has approved WQS variances adopted by states for various
designated uses and criteria.\120\ For example, states may adopt WQS
variances for dischargers based on a demonstration of substantial and
widespread economic and social impacts consistent with 40 CFR
131.14(b)(2)(i)(A)(1) and 40 CFR 131.10(g)(6). Such WQS variances may
consider circumstances such as the degree to which: permit limits would
become more stringent as a result of revised WQS for which incremental,
though not immediate, improvements could be made; technological
limitations exist; facility space constraints limit installation of
certain technologies; and initial capital costs place significant
burdens on the surrounding community. WQS variances can help mitigate
near-term compliance burdens and costs while
[[Page 46501]]
ensuring effective implementation.\121\ The EPA, in coordination with
the DRBC and the states of Delaware, New Jersey, and Pennsylvania, may
issue further guidance on the available WQS flexibilities and
permitting tools available to address implementation concerns for any
affected entities. Additional information on WQS variances and a WQS
variance building tool is available on the EPA's website.\122\
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\120\ For example: Minnesota (https://www.pca.state.mn.us/business-with-us/water-quality-variances), Wisconsin (https://dnr.wisconsin.gov/topic/Wastewater/variances.html), and Missouri
(https://dnr.mo.gov/water/business-industry-other-entities/variances/water-quality-standards).
\121\ The EPA would review any state-adopted WQS variances on a
case-by-case basis for consistency with CWA section 303(c) and 40
CFR 131.14.
\122\ https://www.epa.gov/wqs-tech/water-quality-standards-variances.
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Regarding the use of compliance schedules, the EPA agrees that
where dischargers need additional time to implement an enforceable
sequence of actions--such as facility upgrades or operation changes--
that will lead to compliance with a water quality-based limit based on
the applicable designated use and criteria, the permitting authority
should consider an NPDES permit compliance schedule, addressed in the
EPA's regulations at 40 CFR 122.47 and 131.15. If a permittee cannot
immediately meet a water quality-based limit, the permitting authority
may include a compliance schedule \123\ in the permit, consistent with
40 CFR 122.47, to provide time to achieve the water quality-based
limit. Generally, a compliance schedule must ``require compliance as
soon as possible.'' \124\ Where a permit compliance schedule is longer
than one year, the NPDES permit must include interim requirements and
dates for their achievement.\125\ The EPA's regulation at 40 CFR 131.15
specifies that if a state intends to authorize the use of compliance
schedules in NPDES permits, ``the [s]tate must adopt a permit
compliance schedule authorizing provision. Such authorizing provision
is a [WQS] subject to EPA review and approval under section 303 of the
[Clean Water] Act and must be consistent with sections 502(17) and
301(b)(1)(C) of the [Clean Water] Act.'' Such compliance schedules may
be used to implement the WQS in this final rule.
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\123\ The definition of ``schedule of compliance'' is available
at 40 CFR 122.2.
\124\ 40 CFR 122.47(a)(1).
\125\ 40 CFR 122.47(a)(3).
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B. Clean Water Act Section 303(d)/305(b) Water Quality Assessments
Delaware, New Jersey, and Pennsylvania each have an obligation
under CWA sections 303(d) and 305(b) to assess whether CWA-effective
WQS in their jurisdictions are being attained. The EPA anticipates that
there may be a period of time immediately after issuance of this final
rule when the WQS will not be attained because the actions and
procedures required to achieve compliance will take time to implement.
In this scenario, any of the relevant zones not attaining the WQS
should be classified as impaired on the relevant CWA section(s) 303(d)/
305(b) Integrated Report(s) (IR) submitted to the EPA for review.
Per the CWA and the EPA's implementing regulations, waters that are
assessed under CWA section 303(d) as impaired by a pollutant typically
require the development of a Total Maximum Daily Load (TMDL), which is
a regulatory planning tool designed to restore water quality via
allocations of pollutant reductions to relevant point and non-point
sources. The EPA's regulations also recognize that other pollution
control requirements may obviate the need for a TMDL. Specifically,
impaired waters do not require a TMDL if (1) technology-based effluent
limitations required by the CWA, (2) more stringent effluent
limitations required by a state, local, or Federal authority, or (3)
other pollution control requirements (e.g., best management practices)
required by a state, local, or Federal authority are stringent enough
to implement applicable WQS.\126\ Impaired waters that do not require a
TMDL because one of these alternatives is satisfied are commonly
referred to as Category 4b waters, as described in the EPA's Integrated
Reporting Guidance for CWA sections 303(d), 305(b), and 314.\127\
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\126\ 40 CFR 130.7(b)(1).
\127\ The EPA's Integrated Reporting Guidance is available at:
https://www.epa.gov/tmdl/integrated-reporting-guidance-under-cwa-sections-303d-305b-and-314.
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The DRBC developed a model to evaluate sources of pollution that
affect dissolved oxygen levels in the specified zones of the Delaware
River and concluded that point sources are the primary contributor to
oxygen depletion within those zones.\128\ The EPA's economic analysis
evaluates point source controls that are expected to result in
dissolved oxygen levels that meet the EPA's criteria.\129\ In the
preamble to the proposed rule, the EPA noted that if Delaware, New
Jersey, and/or Pennsylvania require effluent limitations and/or other
pollution control requirements that the EPA agrees are stringent enough
to implement the final dissolved oxygen criteria, the specified zones
may be a candidate for Category 4b in future IRs. The EPA remains
committed to working with Delaware, New Jersey, and Pennsylvania, in
consultation with the DRBC, on future IRs to determine the appropriate
assessment status for the waters that are subject to this rulemaking.
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\128\ Delaware River Basin Commission (2024a, 2024b).
\129\ More details are available in the document, Economic
Analysis for the Final Rule: Water Quality Standards to Protect
Aquatic Life in the Delaware River.
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VIII. Economic Analysis
The EPA conducted an economic analysis pursuant to Executive Order
12866 to evaluate the potential benefits and costs associated with this
final rule. The EPA prepared this analysis of one potential
implementation scenario for informational purposes to provide the
public and potentially affected entities with estimates of the
potential costs and benefits that could accrue when the relevant states
implement this final rule. The EPA did not rely upon this economic
analysis in setting these WQS. For more information about how costs are
addressed in the WQS context, please refer to the associated response
to comments document. Despite evaluation of one potential
implementation scenario in the economic analysis, the EPA's rule does
not prescribe any specific pollutant controls, and the EPA expects that
states will work with affected dischargers to identify the most
appropriate compliance options.
In the high-level summary of the EPA's economic analysis below, the
EPA first describes a baseline scenario that is intended to
characterize the world in the absence of the EPA's rule. Next, the EPA
describes the development of a policy scenario based on potential
pollution control actions that, if implemented, can be expected to meet
the EPA's dissolved oxygen criteria. Finally, the EPA evaluates the
anticipated potential costs associated with the policy scenario and the
potential benefits of the specified zones attaining the EPA's dissolved
oxygen criteria. More details and information are available in the
associated document, Economic Analysis for the Final Rule: Water
Quality Standards to Protect Aquatic Life in the Delaware River,
available in the docket for this rule.
A. Baseline for the Analysis
The baseline is intended to characterize the world in the absence
of the EPA's rule. The EPA typically assumes full compliance with
existing regulations and requirements--including Combined Sewer
Overflow (CSO) Long-Term Control Plans
[[Page 46502]]
(LTCPs) \130\--even if they are not yet fully implemented, as a basis
for estimating the benefits and costs of regulations. This baseline
approach ensures that the benefits and costs of the existing
regulations and requirements are not double counted.
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\130\ As provided in the CSO Control Policy, incorporated under
CWA section 402(q), ``[NPDES p]ermittees with CSOs are responsible
for developing and implementing long-term CSO control plans [or
LTCP] that will ultimately result in compliance with the
requirements of the CWA.'' CSO Control Policy, 59 FR 18688, 18691
(April. 19, 1994).
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In this economic analysis, the EPA assumes that without the final
rule, the prior, less stringent WQS (that do not adequately support
aquatic life propagation) would have remained in effect. Accordingly,
the EPA assumes that water quality conditions in the specified zones of
the Delaware River, particularly during the Juvenile Development season
(July 1 to October 31), would continue to exhibit low oxygen levels
that do not adequately support aquatic life propagation, even with
implementation of existing and planned CSO LTCPs, as well as other
related expansions or plans.\131\ Along the specified zones of the
Delaware River, there are three combined sewer systems with CSO LTCPs
that are relevant for consideration by the EPA as part of the baseline.
The Philadelphia Water Department, Camden County Municipal Utilities
Authority, and Delaware County Regional Water Quality Control Authority
all have LTCPs that are either approved or in progress.\132\ The EPA
expects implementation of these LTCPs, when finalized, to occur
regardless of the EPA's final rule. Therefore, the EPA included
estimated CSO volume reductions for these three dischargers as part of
the baseline for this economic analysis.
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\131\ While the EPA normally assumes full compliance with
existing LTCPs, for this rule, the EPA is also assuming full
compliance with planned LTCPs. Because planned LTCPs are not final
and therefore are subject to change, this adds uncertainty to the
baseline conditions.
\132\ Delaware River Basin Commission (2024a);
DELCORA. (2023). Combined Sewer System: DELCORA CSO LTCP.
https://www.delcora.org/combined-sewer-systems/delcora-cso-ltcp/;
Philadelphia Water Department. (2023). CSO Long Term Control
Plan. https://water.phila.gov/reporting/ltcp/;
State of New Jersey Division of Water Quality. (2023). Long Term
Control Plan Submittals. https://www.nj.gov/dep/dwq/cso-ltcpsubmittals.htm.
---------------------------------------------------------------------------
During the public comment period, the EPA received comments
regarding the consideration of CSO LTCPs in the EPA's economic
analysis. Some commenters asserted that the EPA should address CSO
control costs in the economic analysis, while other commenters asserted
that these LTCPs would not be completed either at all or prior to
promulgation of the final rule. The EPA disagrees with commenters'
assertions that the Agency should include CSO control costs as part of
the cost analysis for the EPA's rule. CSO controls are expected to be
implemented at certain wastewater treatment plants, described above,
along the specified zones of the Delaware River regardless of the EPA's
rule; therefore, costs associated with these controls cannot be
attributed to the EPA's rule. The EPA acknowledges that the assumption
of full compliance with draft LTCPs, in addition to final LTCPs, could
add uncertainty to baseline conditions since draft LTCPs are subject to
change. The EPA includes a discussion of this uncertainty in table 2-1
of the associated economic analysis. However, the EPA notes that these
draft LTCPs represent the best available information on planned CSO
controls and are therefore appropriately used in the economic analysis.
The DRBC modeled the effect of pollution reduction on dissolved
oxygen levels in the Delaware River and provided the EPA with water
quality simulation results under both baseline and ``restored''
conditions for the years 2012, 2018, and 2019.\133\ Baseline
simulations predict water quality conditions associated with the
discharge of actual wastewater treatment plant (WWTP) flows at existing
levels of treatment and after full implementation of existing and
planned LTCPs. The restored simulations predict water quality
conditions associated with the discharge of actual WWTP flows at
treatment levels that include additional effluent treatment and after
full implementation of LTCPs.
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\133\ The EPA determined that the model runs from the DRBC were
sufficient for use in this economic analysis. Delaware River Basin
Commission (2024b).
---------------------------------------------------------------------------
Of the three available years (2012, 2018, and 2019), the EPA
selected 2019 as representative of the most typical conditions in the
relevant zones of the Delaware River. In comparison, 2012 had
atypically poor conditions (low percent oxygen saturation, high water
temperature), while 2018 had atypically good conditions (high percent
oxygen saturation, low water temperature). Therefore, model runs used
in this economic analysis are based on 2019 conditions.
One commenter asserted that the EPA's use of a single year of water
quality data reduced the reliability of the EPA's technical and
economic assessments because a single year cannot be relied upon to
predict how future infrastructure might address pollution, given
interannual variations in precipitation and temperature. The EPA
acknowledges that relying on a single year of data limits the ability
of the economic analysis to reflect any future changes in water
temperature and/or precipitation. However, as discussed in the
associated technical support document and in the response to comments
document, there are no existing modeling studies that directly predict
future water temperatures in the specified zones of the Delaware River,
which limits the EPA from factoring these future conditions into
additional analyses. Given these limitations, the economic analysis
relies on the most representative year of data available and therefore,
this approach to the analysis was reasonable.
B. Development of the Policy Scenario
There is a wide range of potential paths that Delaware, New Jersey,
and Pennsylvania may choose to take when implementing the EPA's final
WQS. For this economic analysis, the EPA relied on available data to
develop a policy scenario based on modeled pollution controls developed
by the DRBC that the EPA expects would meet the Agency's dissolved
oxygen criteria. Actual benefits, costs, and impacts will depend on the
choices that states make in implementing the final WQS, which may
differ from the policy scenario presented in this economic analysis.
The EPA's dissolved oxygen criteria apply to three seasons;
therefore, when developing a single policy scenario, the EPA evaluated
potential pollution control actions that would be expected to meet the
EPA's criteria in each of the three seasons. The EPA began by
evaluating water quality monitoring data for the past decade from two
continuous monitoring stations in the relevant zones of the Delaware
River--Penn's Landing in Zone 3 and Chester in Zone 4. As noted in
section III.C.3. of this preamble, based on the monitoring data, the
EPA expects that the Agency's dissolved oxygen criteria for the
Spawning and Larval Development and Overwintering seasons will likely
be met without the need for additional WWTP upgrades or other controls
beyond those accounted for in the baseline simulation. Monitoring data
for the Juvenile Development season indicated that additional pollution
control actions are likely necessary to meet the EPA's criteria in that
season. To develop a policy scenario for the Juvenile Development
season, the EPA relied on modeled data from the DRBC predicting oxygen
levels in 2019 in the specified
[[Page 46503]]
zones of the Delaware River following a set of WWTP pollution control
actions for certain dischargers. Modeled data for restored conditions
are described in the baseline section above in this preamble, while
WWTP controls are described in the cost section below in this preamble.
The EPA expects that this policy scenario (hereafter, the 2019 restored
scenario) will meet the final criteria during the Juvenile Development
season.
C. Potential Costs
The EPA estimated compliance costs for the final WQS based on
estimates for WWTPs to reduce effluent ammonia nitrogen concentrations
and raise effluent dissolved oxygen concentrations. Although there are
several causes that contribute to low dissolved oxygen conditions in
the specified zones of the Delaware River, the DRBC identified ammonia
nitrogen loadings from WWTPs as the leading cause of oxygen-depletion
in the river.\134\ The DRBC also identified controlling these loads as
a feasible solution to addressing dissolved oxygen conditions through
their modeling efforts. As a result, for this economic analysis, the
EPA assumed that implementation of additional pollution control
technologies at WWTPs is the most likely way that Delaware, New Jersey,
and Pennsylvania will implement the final WQS. Therefore, the EPA
evaluated WWTP controls rather than other controls, such as non-point
source controls, for this cost analysis.
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\134\ Delaware River Basin Commission (2024a).
---------------------------------------------------------------------------
Some commenters asserted that the EPA should consider habitat
restoration and pollution reductions other than ammonia treatment
controls at wastewater treatment plants. While the EPA did consider
other sources of nutrients into the Delaware River, the Agency
concluded that point source controls are the most likely pathway that
Delaware, New Jersey, and Pennsylvania would choose to take when
implementing the rule. However, the EPA's rule does not preclude each
state from evaluating controls on other pollutant sources, including
non-point sources, or evaluating the potential benefits of habitat
restoration, and the EPA encourages each state to consider all
available and relevant pollution control approaches when implementing
the Federal standards.
The EPA relied on cost information from several DRBC studies to
estimate the costs of achieving the final WQS.\135\ The DRBC's A
Pathway for Continued Restoration: Improving Dissolved Oxygen in the
Delaware River Estuary report categorized WWTPs as either class A', A,
or B facilities.\136\ The DRBC determined that discharges from Class
A', A, and B facilities have a major impact, a marginal impact, or no
measurable impact on oxygen levels in the specified zones,
respectively. The EPA's 2019 restored scenario follows the DRBC's
approach by including the seven Class A' and two Class A facilities and
excluding the three Class B facilities.\137\
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\135\ Id.; Kleinfelder Inc. (2021). Nitrogen Reduction Cost
Estimation Study Final Summary Report. https://www.nj.gov/drbc/library/documents/NitrogenReductionCostEstimates_KleinfelderJan2021.pdf;
Kleinfelder Inc. (2023). Delaware River Basin Commission
Nitrogen Reduction Cost Estimation Study--Supplemental Cost Addendum
2 Technical Memorandum--Final. https://www.nj.gov/drbc/library/documents/NitrogenReductionCostEstimates_Kleinfelder_aug2023addendum.pdf.
\136\ Delaware River Basin Commission (2024a).
\137\ Id.
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The EPA used WWTP-specific (capital, operations and maintenance
(O&M)) compliance costs from Kleinfelder Inc. (2021, 2023) to estimate
compliance costs, based on the discharger classification. Total
compliance costs include the costs associated with both of the
following:
1. Class A' Facilities (7 WWTPs): Reductions in effluent ammonia
nitrogen concentrations to 1.5 mg/L from May 1 through October 31
and increases in effluent oxygen concentrations to a monthly average
of 6 mg/L year-round.\138\
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\138\ These effluent concentrations are consistent with the
DRBC's own water quality regulations, adopted in 1967, and modified
in 1992 to reflect that ``Best Demonstrable Technology (BDT)'' for
new or expanding wastewater treatment facilities was 1.5 mg/L or
less of ammonia nitrogen and 6.0 mg/L or greater of dissolved
oxygen. These BDT requirements are applicable to wastewater
discharges within the 197-mile non-tidal portion of the Delaware
River, immediately upstream of the specified zones in the EPA's
rule. Delaware River Basin Commission. ``Administrative Manual--Part
III Water Quality Regulations with Amendments Through December 7,
2022.'' Accessed August 7, 2024. https://www.nj.gov/drbc/library/documents/WQregs.pdf.
Further, a nationwide evaluation of discharge concentrations
among ``major'' NPDES-permitted wastewater treatment plants (i.e.,
facilities that discharge more than 1 million gallons of effluent
per day) indicates that roughly 75% are discharging ammonia at
levels necessary to achieve compliance with the EPA's dissolved
oxygen criteria for the Delaware River. United States Environmental
Protection Agency (2025). Nutrient Removal Study Dashboard. Web
page. Accessed May 23, 2025. https://ordspub.epa.gov/ords/wfc/f?p=259:49:8670036276255.
The EPA acknowledges that the operation time period for the
treatment technologies that are necessary to meet the final WQS may
differ from the assumptions in Kleinfelder Inc. (2021, 2023). Actual
operation time periods will impact the technology lifespan and O&M
costs. Since time period assumptions in Kleinfelder Inc. (2021,
2023) exceed the July 1-October 31 Juvenile Development season, O&M
costs may be overestimated.
---------------------------------------------------------------------------
2. Class A Facilities (2 WWTPs): Reductions in effluent ammonia
nitrogen concentrations to 5 mg/L from May 1 through October 31.
Some commenters expressed concerns with the EPA's reliance on
information published or commissioned by the DRBC. These commenters
asserted that the cost estimates from the Kleinfelder reports were
unrealistically low, a limited number of economic variables were
considered, and costs associated with other regulatory mandates were
not considered, among other concerns. The EPA disagrees that basing the
Agency's economic analysis on inputs from previous DRBC analyses is
inappropriate. The DRBC analyses reflect the most reliable, up-to-date
information on pollution, pollution controls, and dissolved oxygen
conditions in the Delaware River. The ammonia nitrogen treatment
technologies that the DRBC costed for are proven treatment technologies
(i.e., readily available, established technologies with long-term
performance records) that are reasonably expected to attain the EPA's
criteria. Wastewater treatment plants might be able to achieve the
target effluent limits at a lower cost through more efficient
technological or operational upgrades. Many comparable wastewater
treatment plants, including several in major cities on the U.S. East
Coast (e.g., Washington DC, Baltimore, New York City, Pittsburgh), have
already installed and are using similar technologies to treat ammonia
nitrogen to levels at or below the levels the EPA expects will result
in attainment of the EPA's final dissolved oxygen criteria for the
specified zones of the Delaware River. As such, a majority of similarly
situated dischargers have been able to comply with comparably stringent
dissolved oxygen-related discharge limits that support fish propagation
designated uses. The EPA performed data quality checks (e.g., compared
results to observed data, checked for outliers) before using the DRBC
analyses in the economic analysis. Regarding the Kleinfelder cost
estimates, the DRBC coordinated extensively with dischargers in
development of the Kleinfelder report, and incorporated comments from
dischargers into the final report as appropriate. The EPA considers
regulatory mandates as part of the baseline that is unaffected by this
rulemaking and those mandates are therefore not applicable to the EPA's
cost estimates for this rule.
[[Page 46504]]
The EPA assumed capital costs occur upfront in 2026 followed by a
five-year construction period. Consistent with Kleinfelder Inc. (2021,
2023), the EPA assumed O&M costs occur over a 25-year period from 2031
through 2055. The EPA then annualized costs over a 30-year analysis
period between 2026 and 2055 and discounted all cost values to 2025,
using 3 and 7 percent discount rates and payment at the beginning of
each year in the analysis period.
Some commenters asserted that the EPA underestimated the costs of
the rule. In particular, one commenter asserted that the EPA
underestimated costs at the Philadelphia Water Department's (PWD's)
wastewater treatment plants by between $1.3 billion and $2.5 billion.
The EPA disagrees. The EPA's cost analysis is based on one potential
implementation scenario using cost estimates based on proven wastewater
treatment plant treatment technologies (i.e., established technologies
with long-term performance records), including the standard practice of
a 30% contingency to reflect a pre-design planning level of accuracy,
without consideration of whether other technologies might be more cost
effective for each individual treatment plant. Regarding cost estimates
for the PWD facilities, the EPA requested and received additional
information from PWD regarding its cost estimates. The EPA determined
that PWD proposed a different and more expensive technology approach
than the EPA, which is not necessary for compliance with the revised
WQS, so the EPA retained the Kleinfelder Inc.-based estimates for the
final economic analysis.\139\ Thus, the EPA concluded it is reasonable
to cost for a less expensive technology that can achieve compliance
with the revised WQS and therefore, the EPA's cost estimates are
reasonable. However, to account for additional uncertainty in the cost
estimates, for the final rule and in response to public comments, the
EPA applied ``expected accuracy range'' values (-15 percent for a low
estimate and +20 percent for a high estimate) from the Association for
the Advancement of Cost Engineering to produce low and high
estimates.\140\ The EPA used expected accuracy range values for Class 4
estimates for consistency with the class of estimates used by
Kleinfelder Inc. (2021). The EPA applied expected accuracy range values
to the central cost estimates to present low, central, and high
estimates for the annualized compliance costs associated with achieving
the EPA's final WQS, using 3 and 7 percent discount rates (table 9 of
this preamble).
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\139\ Additional information comparing the EPA's and PWD's cost
estimates is available in the associated response to comments
document.
\140\ Christensen, P., Dysert, L.R., Bates, J., Burton, D.,
Creese, R., & Hollmann, J. (2005). Cost Estimate Classification
system-as Applied in Engineering, Procurement, and Construction for
the Process Industries: TCM Framework: 7.3--Cost Estimating and
Budgeting. AACE International Recommended Practices, 18R-97, 1-9.
---------------------------------------------------------------------------
Using a 3 percent discount rate, the estimated total annualized
compliance cost for nine WWTPs ranges from $121.6 million to $171.6
million, with a central estimate of $143.0 million (2024$). These costs
vary considerably between the nine WWTPs (based on flow and
technology), with central estimates ranging from $2.0 million at the
Lower Bucks County Joint Municipal Authority WWTP to $39.2 million at
the PWD Southwest Water Pollution Control Plant (2024$). Among the
dischargers, PWD bears the highest proportion of total costs, with its
three facilities' combined costs accounting for over 50 percent of
total costs. Overall, across all dischargers, approximately 66 percent
of the costs are attributable to capital and 34 percent are
attributable to O&M. Using a 7 percent discount rate, the estimated
total annualized compliance cost for nine WWTPs ranges from $157.8
million to $222.7 million, with a central estimate of $185.6 million
(2024$).
Table 9--Annualized Compliance Costs Using 3 and 7 Percent Discount Rates
[Million 2024$]
----------------------------------------------------------------------------------------------------------------
Annualized costs (3% Annualized costs (7%
discount rate) discount rate)
Plant State Class -----------------------------------------------------------
Low Central High Low Central High
----------------------------------------------------------------------------------------------------------------
Camden County Municipal NJ A' $14.3 $16.9 $20.2 $17.2 $20.2 $24.2
Utilities Authority.
City of Wilmington............ DE A' 21.2 24.9 29.9 27.7 32.6 39.1
Delaware County Regional Water PA A' 8.0 9.4 11.3 10.5 12.4 14.9
Pollution Control Authority.
Gloucester County Utilities NJ A' 4.3 5.1 6.1 4.6 5.4 6.5
Authority.
PWD Northeast Water Pollution PA A' 23.2 27.3 32.8 33.7 39.7 47.6
Control Plant.
PWD Southeast Water Pollution PA A' 12.5 14.7 17.6 18.3 21.5 25.8
Control Plant.
PWD Southwest Water Pollution PA A' 33.3 39.2 47.1 40.2 47.3 56.8
Control Plant.
Hamilton Township............. NJ A 2.9 3.4 4.1 3.7 4.3 5.2
Lower Bucks County Joint PA A 1.7 2.0 2.4 2.0 2.3 2.8
Municipal Authority.
-----------------------------------------------------------
Total..................... ......... ......... 121.6 143.0 171.6 157.8 185.6 222.7
----------------------------------------------------------------------------------------------------------------
Some commenters asserted that the EPA did not correctly account for
the impact of increased debt service costs that would occur from the
EPA's rule. The EPA disagrees with the assertion that the Agency did
not properly account for debt service costs. As explained in the
associated economic analysis, the EPA's economic analysis focuses on
social costs, the total cost to society. In this context, it does not
take more of society's real resources to finance through debt than when
paid or financed in another way. The EPA notes that the Agency has
followed OMB's Circular A-4 guidance for the presentation of annualized
costs.\141\
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\141\ Office of Management and Budget. (2003). Circular A-4.
Subject: Regulatory Analysis. Retrieved from https://obamawhitehouse.archives.gov/omb/circulars_a004_a-4/.
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Some commenters stated that wastewater treatment plants face future
substantial capital expenditures that are necessary to fulfill other
infrastructure, public health, operational, and regulatory obligations,
which the proposed rule did not fully consider. Commenters also
suggested that state, Federal, or grant funding should be made
available to cover the costs of the EPA's rule. The EPA acknowledges
that entities affected by this rulemaking have limited budgets and
might have capital expenditures allocated to other projects related to
protecting public health and the environment, infrastructure, or other
[[Page 46505]]
regulatory obligations. The EPA's economic analysis is intended to
provide information regarding the potential social costs associated
with this rule and is not intended to provide a holistic picture of a
particular utility's or municipality's financial commitments or
anticipated future commitments. As described above, other regulatory
obligations or budgetary commitments would be considered part of the
analysis baseline since they are expected to occur in the absence of
the EPA's rule. The EPA notes that wastewater treatment plants may have
various financing options available, such as low-interest loans through
state revolving funds, and will presumably pursue the option that works
best for their individual circumstances.
D. Potential Benefits
Water quality improvements can have a wide range of effects on
water resources and the environmental goods and services that they
provide, including services valued by people (e.g., recreation,
commercial fishing, aesthetic beauty, support and preservation of
aquatic life and wildlife). Some environmental goods and services
(e.g., commercially caught fish) are traded in markets, and thus their
value may be directly observed. Other environmental goods and services
(e.g., recreation and support of aquatic life) cannot be bought or sold
directly and thus do not have observable market values; these types of
environmental goods and services are classified as ``non-market.'' The
non-market values of environmental goods and services include both use
(e.g., recreation) and nonuse (e.g., existence and bequest) values.
The EPA used a benefit transfer approach based on a meta-analysis
of surface water valuation studies to evaluate the non-market benefits
(including both use and nonuse values) of improved surface water
quality resulting from achievement of the EPA's final WQS in the 2019
restored scenario. The benefit transfer approach involves three main
steps:
1. Estimate water quality improvements associated with
attainment of the EPA's final WQS relative to the baseline;
2. Translate these improvements into a water quality index (WQI)
that can be linked to ecosystem services and uses that are valued by
society. The WQI used for this analysis includes six parameters:
dissolved oxygen, biochemical oxygen demand, fecal coliform, total
nitrogen, total phosphorus, and total suspended solids; and
3. Estimate the dollar value of the water quality improvements
based on estimates of the public's willingness-to-pay (WTP) derived
from a meta-analysis of surface water valuation studies. For the
final rule, the EPA used a locally weighted application of the meta-
analysis.142 143
---------------------------------------------------------------------------
\142\ Additional details are available in section 4.3 and
Appendices C and D in the associated economic analysis.
\143\ The EPA has used a benefit transfer approach based on the
meta-analysis of surface water valuation studies on numerous
occasions, for example, Benefit and Cost Analysis for Revisions to
the Effluent Limitations Guidelines and Standards for the Steam
Electric Power Generating Point Source Category (U.S. Environmental
Protection Agency. (2020). Benefit and Cost Analysis for Revisions
to the Effluent Limitations Guidelines and Standards for the Steam
Electric Power Generating Point Source Category. (EPA-821-R-20-
003)). The locally weighted regression approach used for the final
rule builds upon this approach by reducing error associated with
benefit transfer.
To assess baseline water quality, the EPA obtained water quality
modeling data of baseline conditions from the DRBC, including dissolved
oxygen, total nitrogen, and total phosphorus levels for various
effluent treatment scenarios. For the remaining parameters included in
the WQI (i.e., biochemical oxygen demand, fecal coliform, and total
suspended solids), the EPA relied on monitoring data at various
locations within the specified zones. To assess water quality under the
2019 restored scenario, the EPA used the DRBC's modeled output of
dissolved oxygen levels in the specified zones following implementation
of effluent controls (described above in the cost section of this
preamble), making minor adjustments as needed to ensure that predicted
oxygen levels meet the EPA's final WQS.\144\
---------------------------------------------------------------------------
\144\ The EPA selectively adjusted the daily modeled dissolved
oxygen concentrations in each model cell within the specified zones
to meet the final WQS. In total, the EPA adjusted approximately ten
percent of observations in the modeled dataset to meet the dissolved
oxygen criteria during the Juvenile Development season. The EPA did
not estimate costs for additional treatment technologies to account
for the minimal adjustments needed to the modeled dissolved oxygen
values. The calculated differences between modeled dissolved oxygen
and the EPA's final criteria are within the bounds of uncertainty
related to dissolved oxygen measurements and model assumptions.
---------------------------------------------------------------------------
The effluent treatment measures implemented for the 2019 restored
scenario will directly affect the amount of ammonia nitrogen discharged
to the specified zones of the Delaware River and therefore also reduce
biochemical oxygen demand. Given the inverse proportional relationship
between biological oxygen demand and dissolved oxygen levels, the EPA
approximated biochemical oxygen demand concentrations following
effluent treatment by assuming that baseline biochemical oxygen demand
concentrations are reduced by the same percentage change that dissolved
oxygen improves within each zone (i.e., Zone 3, 4, and Upper 5) of the
model. Table 10 of this preamble summarizes the percent change in
dissolved oxygen and biochemical oxygen demand by zone between the
baseline and the 2019 restored scenario. The EPA kept levels for the
remaining parameters (total nitrogen, total phosphorus, total suspended
solids, and fecal coliform) unchanged from baseline conditions.
Table 10--Dissolved Oxygen and Biochemical Oxygen Demand Changes Between
the Baseline and 2019 Restored Scenarios
------------------------------------------------------------------------
Zone % Change from baseline \a\
------------------------------------------------------------------------
3.......................................... 11.1
4.......................................... 19.9
5-upper.................................... 7.6
------------------------------------------------------------------------
\a\ The percent change for dissolved oxygen and biochemical oxygen
demand is the same, but in opposite directions, i.e., the percent
decrease in biochemical oxygen demand concentration is the same as the
percent increase in dissolved oxygen concentration.
[[Page 46506]]
To quantify benefits of water quality improvements, as is
consistent with past practice, the EPA analyzed the values held by
households residing within 100 miles of the specified zones of the
Delaware River for water quality improvements associated with the EPA's
final WQS.\145\ Households may consider waters unaffected by the EPA's
rule to be substitute waters for those affected, and this can influence
what households are willing to pay for improvements associated with the
final WQS. The EPA deems similar waters unaffected by the rule within
the 100-mile buffer around each census block group as viable
substitutes.\146\
---------------------------------------------------------------------------
\145\ The EPA's 100-mile radius assumption follows Viscusi et
al. (2008), which states: ``The survey defined relevant water
quality as residing in a region that is `a 2-hour drive or so of
your home, in other words, within 100 miles.' About 80 percent of
all recreational uses of bodies of water are within such a radius of
users' homes.'' This 80 percent figure was based on data generated
by the EPA from the 1996 National Survey on Recreation and the
Environment. Data indicates that 77.9 percent of boating visits,
78.1 percent of fishing visits, and 76.9 percent of swimming
recreational visits are within a 100-mile radius of a given
waterbody. (Citation: Viscusi, W.K., Huber, J., & Bell, J. (2008).
The economic value of water quality. Environmental and resource
economics, 41(2), 169-187).
\146\ The EPA defined ``similar waters'' as waters with a stream
order of five or higher.
---------------------------------------------------------------------------
One commenter asserted that the 100-mile distance buffer used by
the EPA is inappropriate for a localized policy, while another
commenter stated that using the 100-mile radius does not consider the
limited access and recreational experience of the river near
Philadelphia, and it includes many households that likely only hold
nonuse value for the resource. The EPA disagrees that use of a 100-mile
radius for estimating benefits of a localized policy is inappropriate.
The EPA followed best practices from the resource valuation literature
to define the ``extent of market'' of affected households, or locations
of households likely to hold values for water quality improvements in
the specified zones of the Delaware River. For example, many water
quality valuation studies considered the entire state or region in
which the affected waterbodies reside as the appropriate extent of the
market.\147\ The EPA acknowledges that WTP for water quality
improvements is likely to vary within the 100-mile range based on
proximity to the specified zones of the Delaware River, recreational
use of the affected waters, or property ownership. The EPA's estimated
household WTP value represents an average across all households
residing within the 100-mile radius. However, the Agency did not use an
equal household WTP throughout the 100-mile radius, but rather, model
variables account for Census block group-level differences within the
100-mile radius. The EPA also disagrees with the commenter that the
Agency did not account for the presence of competing water bodies in
the region. The EPA's model for this economic analysis includes a
variable to account for the size of affected resources (i.e., specified
zones of the Delaware River) relative to the size of substitute waters
within the 100-mile radius.
---------------------------------------------------------------------------
\147\ For example, Johnston, R.J., Moeltner, K., Peery, S.,
Ndebele, T., Yao, Z., Crema, S., Wollheim, W.M., and Besedin, E.Y.
(2023). Spatial dimensions of water quality value in New England
river networks. Proceedings of the National Academy of Sciences,
120(18), e2120255119. https://doi.org/10.1073/pnas.2120255119;
Lupi, F., Herriges, J.A., Kim, H., & Stevenson, R.J. (2023).
Getting off the ladder: Disentangling water quality indices to
enhance the valuation of divergent ecosystem services. Proceedings
of the National Academy of Sciences, 120(18), e2120261120. https://doi.org/10.1073/pnas.2120261120;
Moore, C., Guignet, D., Dockins, C., Maguire, K.B., & Simon,
N.B. (2018). Valuing Ecological Improvements in the Chesapeake Bay
and the Importance of Ancillary Benefits. Journal of Benefit-Cost
Analysis, 9(1), 1-26. https://doi.org/10.1017/bca.2017.9.
---------------------------------------------------------------------------
The EPA estimated the economic value of water quality changes using
results of a meta-analysis of total WTP estimates (including both use
and nonuse values) for water quality improvements, provided by original
studies conducted between 1981 and 2017. Using information extracted
from these studies, the EPA estimated an econometric model that
calculates total WTP for changes in a variety of environmental services
affected by water quality and valued by people, including changes in
recreational fishing opportunities, other water-based recreation, and
existence services such as aquatic life, wildlife, and habitat
designated uses. The model also allows the EPA to adjust WTP values
based on the core geospatial factors predicted by theory to influence
WTP, including scale (the size of affected resources or areas), market
extent (the size of the area over which WTP is estimated), and the
availability of substitute waters. The model also takes into account
important characteristics, such as population and income, which vary
spatially. For the proposed rule, the EPA used the standard model
application used in prior EPA rulemakings.\148\ For the final rule, the
EPA used a locally weighted application of the model.\149\ The locally
weighted regression approach is a flexible regression approach that can
attach larger weights to study observations more similar to the area
affected by the rule (e.g., similar income levels or similar land use)
and less weight to dissimilar observations. This flexibility allows the
locally weighted regression approach to often be better suited for
benefit transfer than the standard meta-regression approach with
universally fixed coefficients. In this case, the 95 percent confidence
bounds for annual household WTP using the locally weighted regression
method are, on average, approximately 70 percent tighter compared to
those produced by the model used for the proposed rule analysis.\150\
---------------------------------------------------------------------------
\148\ Additional information is available in Appendix C of the
associated economic analysis.
\149\ Additional information is available in Appendix D of the
associated economic analysis.
\150\ Id.
---------------------------------------------------------------------------
Table 11 of this preamble presents estimated household and total
annualized WTP values for water quality improvements following
attainment of the EPA's final WQS, based on the locally weighted
approach, 3 and 7 percent discount rates, and payment at the beginning
of each year in the analysis period.\151\ The total annualized value of
water quality improvements from attainment of the final WQS is $154.9
million using a 3 percent discount rate and $134.3 million using a 7
percent discount rate.
---------------------------------------------------------------------------
\151\ Appendix B of the associated economic analysis reports
benefit estimates using the alternative 2% discount rate reported in
the proposed rule.
[[Page 46507]]
Table 11--Estimated Household and Total Annualized Willingness-To-Pay (WTP) for Water Quality Improvements Under the EPA's Final Water Quality
Standards, Using 3 and 7 Percent Discount Rates
--------------------------------------------------------------------------------------------------------------------------------------------------------
Average number of affected households Average annual WTP per household Total annualized WTP (millions Total annualized WTP (millions
(millions) \a\ (2024$) \b\ \c\ 2024$, 3% discount rate) \b\ \d\ 2024$, 7% discount rate) \b\ \d\
--------------------------------------------------------------------------------------------------------------------------------------------------------
15.49 $10.90 $154.9 $134.3
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Average number of affected households during the 2026-2055 analysis period. The number of households for each year in the analysis period accounts
for projected population growth.
\b\ Estimates are based on the locally weighted approach; additional details are available in Appendix D of the associated economic analysis.
\c\ The average annual WTP per household includes values of $0 for the years 2026-2030 when technology implementation will occur. Positive household WTP
values begin during the assumed first year of technology operation (2031) and continue for the estimated lifespan of the technology (25 years, or
through 2055).
\d\ Value is not based on a simple multiplication of the first two columns in the table. Additional details are available in section 4.3 of the
associated economic analysis.
One commenter expressed concerns that the EPA's meta-regression
model overestimated benefits at proposal because, among other reasons,
the EPA assumes the criteria will be attained and does not account for
treatment processes that are under development, such as PWD's
sidestream ammonia treatment facility. The EPA disagrees that
application of the meta-regression model resulted in overestimation of
the rule's benefits. The EPA evaluated high quality modeling data from
the DRBC for a recent year with typical water quality (2019) and
determined that the Agency's potential implementation scenario is
expected to result in criteria attainment, given the DRBC's model
results and associated uncertainties in the model (for example, the
model does not account for changes in sediment oxygen demand, which the
EPA expects to decrease following pollution reductions, thus leading to
higher oxygen levels in the river). Regarding the planned treatment
processes, at the time the EPA conducted the economic analysis for the
proposed rule, PWD had not yet announced its intention of adding a
sidestream ammonia treatment facility to the Southwest Water Pollution
Control Plant. Following announcement of this additional treatment
facility, the EPA accordingly revised the baseline scenario in the
economic analysis for the final rule; please refer to the final rule
economic analysis for more details.
In addition to the quantitative benefits of water quality
improvements resulting from the final WQS, the EPA described additional
benefits qualitatively in section 4.1 of the associated economic
analysis, including recreational and commercial fishing benefits. For
example, the qualitative assessment summarizes the findings of Kauffman
(2019), which estimated that dissolved oxygen improvements similar to
the improvements anticipated under the final rule WQS would improve
annual recreational and commercial fishing benefits in the Delaware
River watershed by $187 million and $24.5 million, respectively
(2024$).\152\
---------------------------------------------------------------------------
\152\ Kauffman, G.J. (2019). Economic benefits of improved water
quality in the Delaware River (USA). River Research and
Applications, 35(10), 1652-1665.
---------------------------------------------------------------------------
E. Conclusion
The EPA estimates that the implementation of additional effluent
treatment controls at certain WWTPs could lead to annualized costs over
30 years of $143.0 million using a 3 percent discount rate and $185.6
million using a 7 percent discount rate (2024$). The EPA has overstated
annualized costs by allocating all capital costs to the first year when
costs would likely be spread across five years. The EPA quantified non-
market benefits through average annual household WTP for water quality
improvements. Annualized monetized non-market benefits from water
quality improvements over 30 years total $154.9 million using a 3
percent discount rate and $134.3 million using a 7 percent discount
rate (2024$). The EPA's monetary estimation of benefits does not
account for benefits related to protections for endangered species
(Atlantic Sturgeon and Shortnose Sturgeon), increased housing values,
or increased commercial fishing, among other benefits. Therefore, the
EPA's estimation of non-market benefits is an underestimate of total
benefits. In addition, the difference between the benefit and cost
estimates to society under 3 percent and 7 percent is due to capital
costs being attributed to the early years of the analysis even though
capital costs will likely be financed throughout the period of
analysis, while the benefits of environmental improvements occur more
evenly throughout the period of analysis. This leads to evaluations
under higher discount rates showing a larger discrepancy between
benefits and costs. Table 12 of this preamble summarizes annualized
cost and benefit estimates for the rule.\153\
---------------------------------------------------------------------------
\153\ Note that annualized costs under a 7% discount rate are
higher than under a 3% discount rate. While a higher discount rate
more heavily discounts the future and therefore discounting will
lead to a lower present value under a 7% rate than a 3% rate, the
annualizing step can appear to produce counterintuitive results
depending on the timing of when future costs will be incurred. Since
capital costs, which occur in 2026, dominate O&M costs, which are
evenly distributed after 2031, once these costs are discounted and
then annualized across the period of analysis, annualized costs
under a 7% discount rate are higher than under a 3% rate.
Conversely, annualized benefits are lower under the 7% discount rate
relative to 3% because benefits are fairly evenly distributed
through time.
Table 12--Annualized Cost and Benefit Estimates
[Million 2024$]
----------------------------------------------------------------------------------------------------------------
3% Discount rate 7% Discount rate
----------------------------------------------------------------------------------------------------------------
Costs................................................................... $143.0 $185.6
Benefits................................................................ 154.9 134.3
---------------------------------------
Net Benefits \a\.................................................... 11.9 -51.3
----------------------------------------------------------------------------------------------------------------
\a\ Net benefits equal benefits minus costs.
[[Page 46508]]
IX. Statutory and Executive Order Reviews
Additional information about these statutes and executive orders
can be found at https://www.epa.gov/laws-regulations/laws-and-executive-orders.
A. Executive Order 12866: Regulatory Planning and Review and Executive
Order 13563: Improving Regulation and Regulatory Review
This action is a significant regulatory action as defined under
section 3(f)(1) of Executive Order 12866. Accordingly, it was submitted
to the Office of Management and Budget (OMB) for review. Any changes
made in response to OMB recommendations have been documented in the
docket. The EPA prepared an analysis of the potential costs and
benefits associated with this action. This analysis, Economic Analysis
for the Final Rule: Water Quality Standards to Protect Aquatic Life in
the Delaware River, is available in the docket and summarized in
section VIII of this preamble.
B. Executive Order 14192: Unleashing Prosperity Through Deregulation
This action is considered an Executive Order 14192 regulatory
action. Details on the estimated costs of this final rule can be found
in the EPA's analysis of the potential costs and benefits associated
with this action.
C. Paperwork Reduction Act (PRA)
This action does not impose any new information collection burden
under the PRA. OMB has previously approved the information collection
activities contained in the existing regulations and has assigned OMB
control number 2040-0049.
D. Regulatory Flexibility Act (RFA)
I certify that this action will not have a significant economic
impact on a substantial number of small entities under the RFA. This
action will not impose any requirements on small entities. Small
entities, such as small businesses or small governmental jurisdictions,
are not directly regulated by this rule.
EPA-promulgated WQS are implemented through various water quality
control programs including the NPDES program, which limits discharges
to navigable waters, except in compliance with a NPDES permit. CWA
section 301(b)(1)(C) and the EPA's implementing regulations at 40 CFR
122.44(d)(1) provide that all NPDES permits must include any limits on
discharges that are necessary to meet applicable WQS. Thus, under the
CWA, the EPA's promulgation of WQS establishes standards that states
implement through the NPDES permit process. While states have
discretion in developing discharge limits, those limits ``must control
all pollutants or pollutant parameters (either conventional,
nonconventional, or toxic pollutants) which the Director determines are
or may be discharged at a level that will cause, have the reasonable
potential to cause, or contribute to an excursion above any [s]tate
water quality standard, including [s]tate narrative criteria for water
quality.'' \154\
---------------------------------------------------------------------------
\154\ 40 CFR 122.44(d)(1)(i).
---------------------------------------------------------------------------
As a result of this action, the states of Delaware, New Jersey, and
Pennsylvania will need to ensure that permits they issue include any
limitations on discharges necessary to comply with the WQS established
in this final rule. In doing so, each state will have several choices
associated with permit writing. While each state's implementation of
the rule may ultimately result in new or revised permit conditions for
some dischargers, including small entities, the EPA's action, by
itself, does not impose any of these requirements on small entities; in
other words, these requirements are not self-implementing.
E. Unfunded Mandates Reform Act (UMRA)
This action does not contain an unfunded mandate as described in
UMRA, 2 U.S.C. 1531-1538, and does not significantly or uniquely affect
small governments. The action imposes no enforceable duty on any state,
local, or tribal governments or the private sector.
F. Executive Order 13132: Federalism
This action does not have federalism implications, as defined in
Executive Order 13132. It will not have substantial direct effects on
the states, on the relationship between the national government and the
states, or on the distribution of power and responsibilities among the
various levels of government. This rule does not alter Delaware's, New
Jersey's, or Pennsylvania's considerable discretion in implementing
these WQS, nor does it preclude any of those states from adopting
revised WQS and submitting them to the EPA for review and approval
after promulgation of this final rule.
G. Executive Order 13175: Consultation and Coordination With Indian
Tribal Governments
This action does not have tribal implications as specified in
Executive Order 13175. This rule will not affect federally recognized
Indian tribes in Delaware, New Jersey, or Pennsylvania because the WQS
would not apply to waters in Indian lands nor affect tribal interests.
Thus, Executive Order 13175 does not apply to this action.
H. Executive Order 13045: Protection of Children From Environmental
Health Risks and Safety Risks
The EPA interprets Executive Order 13045 as applying only to those
regulatory actions that concern environmental health or safety risks
that the EPA has reason to believe may disproportionately affect
children, per the definition of ``covered regulatory action'' in
section 2-202 of the Executive Order. Therefore, this action is not
subject to Executive Order 13045 because it does not concern an
environmental health risk or safety risk. Since this action does not
concern human health, the EPA's Policy on Children's Health also does
not apply.
I. Executive Order 13211: Actions That Significantly Affect Energy
Supply, Distribution, or Use
This action is not a ``significant energy action'' because it is
not likely to have a significant adverse effect on the supply,
distribution, or use of energy. This action establishes Federal WQS for
specified zones of the Delaware River under the jurisdiction of the
states of Delaware, New Jersey, and Pennsylvania.
J. National Technology Transfer and Advancement Act (NTTAA)
This rule does not involve technical standards.
K. Congressional Review Act (CRA)
This action is subject to the CRA, and the EPA will submit a rule
report to Congress and to the Comptroller General of the United States.
This action meets the criteria set forth in 5 U.S.C. 804(2).
List of Subjects in 40 CFR Part 131
Environmental protection, Indians-lands, Intergovernmental
relations, Reporting and recordkeeping requirements, Water pollution
control.
Lee Zeldin,
Administrator.
For the reasons set forth in the preamble, the EPA amends 40 CFR
part 131 as follows:
PART 131--WATER QUALITY STANDARDS
0
1. The authority citation for part 131 continues to read as follows:
Authority: 33 U.S.C. 1251 et seq.
0
2. Add Sec. 131.48 to read as follows:
[[Page 46509]]
Sec. 131.48 Water quality standards to protect aquatic life in the
Delaware River.
(a) Scope. (1) The designated use in paragraph (b) of this section
applies to river miles 108.4 to 70.0 of the mainstem Delaware River for
the States of New Jersey and Pennsylvania.
(2) The aquatic life criteria in paragraph (c) of this section
apply to river miles 108.4 to 70.0 of the mainstem Delaware River for
the States of Delaware, New Jersey, and Pennsylvania.
(b) Aquatic life designated use. The aquatic life designated use is
protection and propagation of resident and migratory aquatic life.
(c) Dissolved oxygen criteria. The applicable dissolved oxygen
criteria are shown in table 1 to this paragraph (c).
Table 1 to Paragraph (c)--Dissolved Oxygen Criteria
----------------------------------------------------------------------------------------------------------------
Magnitude
Season (percent oxygen Duration Exceedance frequency
saturation)
----------------------------------------------------------------------------------------------------------------
Spawning and Larval Development 66 Daily Average.................. 12 Days Cumulative
(March 1-June 30). (10% of the 123-day
season).
Juvenile Development (July 1-October 66 Daily Average.................. 12 Days Cumulative
31). (10% of the 123-day
season).
74 Daily Average.................. 61 Days Cumulative
(50% of the 123-day
season).
Overwintering (November 1-February 66 Daily Average.................. 12 Days Cumulative
28/29). (10% of the 123-day
season).
----------------------------------------------------------------------------------------------------------------
(d) Applicability. (1) The aquatic life designated use in paragraph
(b) of this section applies concurrently with other applicable
designated uses in New Jersey and Pennsylvania for river miles 108.4 to
70.0 of the mainstem Delaware River.
(2) The dissolved oxygen aquatic life water quality criteria in
paragraph (c) of this section are the applicable dissolved oxygen
criteria in Delaware, New Jersey, and Pennsylvania for river miles
108.4 to 70.0 of the mainstem Delaware River and apply concurrently
with other applicable water quality criteria.
(3) The designated use and criteria established are subject to
Delaware's, New Jersey's, and Pennsylvania's general rules of
applicability in the same way and to the same extent as are other
federally promulgated and State-adopted water quality standards in
those States.
[FR Doc. 2025-18816 Filed 9-26-25; 8:45 am]
BILLING CODE 6560-50-P