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Environmental Protection Agency.
The Environmental Protection Agency (EPA) is approving a revision to the California Regional Haze (RH) State Implementation Plan (SIP) submitted by the California Air Resources Board (CARB) documenting that the State's existing plan is making adequate progress to achieve visibility goals by 2018. The revision consists of the California Regional Haze Plan 2014 Progress Report that addresses the Regional Haze Rule (RHR) requirements under the Clean Air Act (CAA) to describe progress in achieving visibility goals in Federally designated Class I areas in California and nearby states. EPA is taking final action to approve California's determination that the existing RH SIP is adequate to meet these visibility goals and requires no substantive revision at this time.
Effective date: This rule is effective May 1, 2015.
EPA has established docket number EPA-R09-OAR-2014-0586 for this action. Generally, documents in the docket are available electronically at http://www.regulations.gov or in hard copy at EPA Region 9, 75 Hawthorne Street, San Francisco, California. Please note that while many of the documents in the docket are listed at http://www.regulations.gov, some information may be publicly available only at the hard copy location (e.g., copyrighted material, large maps, multi-volume reports, or otherwise voluminous materials), and some may not be available at either location (e.g., confidential business information). To inspect the hard copy materials that are publicly available, please schedule an appointment during normal business hours with the contact listed directly below.Start Further Info
FOR FURTHER INFORMATION CONTACT:
Thomas Webb, U.S. EPA, Region 9, Planning Office, Air Division, AIR-2, 75 Hawthorne Street, San Francisco, CA 94105. Thomas Webb may be reached at telephone number (415) 947-4139 and via electronic mail at email@example.com.End Further Info End Preamble Start Supplemental Information
Table of Contents
I. Overview of Proposed Action
II. Public Comments and EPA Responses
III. Summary of Final Action
IV. Statutory and Executive Order Reviews
I. Overview of Proposed Action
EPA proposed on September 29, 2014, to approve the California Regional Haze Plan 2014 Progress Report (“Progress Report” or “Report”) as a revision to the California RH SIP. CARB submitted the Progress Report to EPA on June 16, 2014, to address the RHR requirements at 40 CFR 51.308(g), (h), and (i). As described in our proposal, CARB demonstrated that the emission control measures in the existing California RH SIP are sufficient to enable California, as well as other states with Class I areas affected by emissions from sources in California, to meet all established visibility goals (known as reasonable progress goals or RPGs) for 2018. Based on our evaluation of the Report, we proposed to approve CARB's determination that the California RH SIP requires no substantive revision at this time. We also proposed to find that CARB fulfilled the requirements in 51.308(i)(2), (3), and (4) to provide Federal Land Managers (FLMs) with an opportunity to consult on the RH SIP revision, describe how CARB addressed the FLMs' comments, and provide procedures for continuing the consultation. Please refer to our proposed rule for background information on the RHR, the California RH SIP, and the specific requirements for Progress Reports.
II. Public Comments and EPA Responses
EPA's proposed action provided for a public comment period that, upon request, was extended to 60 days ending on November 28, 2014. We received one set of comments from the National Parks Conservation Association (NPCA). NPCA's comments and our responses are summarized below.Start Printed Page 17328
A. General Comments
Comment: In a number of its comments, NPCA requested that EPA provide information or analysis that is not included in CARB's Progress Report. In several instances, NPCA requested that EPA include such information by revising the CARB's Progress Report itself. For example, NPCA requested that EPA revise the Report to include emissions from natural sources, impacts of pollutant species, estimates of emission trends from sources outside the State, and reduced RPGs that reflect progress to date,
Response: EPA's role is to review progress reports as they are submitted by the states and to either approve or disapprove them based on a comparison of their content to the requirements of the Regional Haze Rule. EPA is not able to revise a state's progress report, and we are not obligated to develop a progress report ourselves if we approve the state's progress report. In the case of California's Progress Report, EPA's proposed approval is based on our determination that CARB has adequately addressed the requirements in 40 CFR 51.308(g) and (h) through the information provided in its Report. CARB provided an opportunity for public comment before submitting its Report to EPA, which would have been the opportune time to address the contents. Otherwise, the State is under no obligation to provide information beyond what is required by Rule. While additional information or different types of analysis would potentially add value, we must evaluate the State's Progress Report based on its contents in relation to the statutory and regulatory requirements. As explained in our responses to specific comments below, the commenter has not identified any such requirements which the Progress Report fails to meet, nor has the commenter identified any shortcomings in the data or analysis upon which the Report relies. Accordingly, EPA has no obligation to supplement the Progress Report's contents or to disapprove the Report.
Comment: NPCA encouraged EPA and California to begin identifying potential sources of emission reductions for the 2018 SIP revision, including any gaps in monitoring and emission inventories. Two types of sources mentioned are those that were not subject to Best Available Retrofit Technology (BART) due to low effects on visibility and non-BART point sources.
Response: We agree that additional source analysis is needed in the next phase of the program.
B. Emission Reductions Achieved
Comment: NPCA argued that while the Progress Report accounts for emission reductions, it does not distinguish between emission reductions achieved as a result of the California RH SIP versus reductions achieved as a result of other enforceable measures and voluntary programs. NPCA requested that EPA require the State to revise the Report to quantify the emission reductions achieved specifically by the RH SIP.
Response: We disagree that the CARB has not properly reported on the emission reductions achieved by implementing the measures in the California RH SIP, as required under 40 CFR 51.308(g)(2). Nothing in this provision of the Rule requires a detailed, causal analysis linking specific emission reductions to specific regional haze SIP measures. The RHR is explicitly designed to facilitate the coordination of emissions management strategies for regional haze with those needed to implement national ambient air quality standards (NAAQS). In fact, the RHR prohibits states from adopting RPGs that represent less visibility improvement than is expected to result from the implementation of other CAA requirements during the planning period. Given this requirement, California and other states include in their RH SIPs a number of Federal and State regulations that were in effect or were expected to come into effect during the period covered by the Progress Report that were anticipated to result in reductions of visibility impairing pollutants.
The California RH SIP is based on a number of air quality programs that represent some of the most stringent air pollution controls in the country. These measures include those to achieve ozone, fine particulate matter, and sulfur dioxide NAAQS. Emission reductions also are achieved by installing and operating BART controls on the Valero refinery as required by the RHR. Other measures, for example, are related to innovative programs to reduce mobile source emissions or conserve energy. In essence, the State's plan to improve visibility in its Class I areas is inextricably linked to emission reductions from a variety of programs. Given the plan's reliance on a range of control measures, CARB's Progress Report appropriately summarizes all the emission reductions that the RH SIP encompasses.
Comment: NPCA particularly encouraged EPA to include emission reductions from California's only BART source, the Valero refinery in Benicia, California.
Response: CARB states in its Progress Report  that BART controls were installed and operating at the main stack of the Valero refinery as of February 2011. These controls include an amine scrubber to reduce sulfur dioxide (SO2), a pre-scrubber to remove SO2 and particulate matter of ten microns or less (PM10), and selective catalytic reduction and low-nitrogen oxide (NOX) burners to remove NOX. CARB states that these improvements have resulted in reductions equivalent to 5,731 tons per year (tpy) of SOX, 237 tpy of NOX, and 22 tpy of PM10. These emission reductions, included in the State's plan and in its Progress Report, primarily benefit visibility at the Point Reyes National Seashore. Thus, the State has provided the information that NPCA requested.
Comment: NPCA also encouraged EPA to include a direct comparison of the emission projections used by the WRAP in its model relied upon by California to establish its RPGs versus the most recent emission inventory, to explain any discrepancies and projected changes to 2018.
Response: The RHR does not require a direct comparison of the emission projections used to establish the RPGs in 2018 for the California RH SIP, with the most recent emission inventory used in the Progress Report to summarize emission reductions achieved. To understand better the difficulty of relying on emission inventories to evaluate visibility conditions at individual Class I areas, please refer to the WRAP Regional Haze Rule Reasonable Progress Report Support Document. The Rule does require a state to use updated emission inventories and other data for the comprehensive revision to the RH SIP due in 2018 that establishes new RPGs for 2028.
C. Changes in Visibility Conditions
Comment: NPCA requested that EPA revise the Progress Report to include “natural conditions and the uniform rate of progress (URP) milestones” since these are “the goals by which visibility progress is measured.” NPCA included a table focusing on visibility improvement on worst days, the salient component of which is comparing the Start Printed Page 17329five-year period from 2008-2012 to the URP milestone in 2018.
Response: The RHR in 51.308(g)(3) requires a state to assess visibility for most impaired and least impaired days based on five-year averages at each Class I area for current conditions, current compared to baseline conditions, and over the past five years. As stated in the title of 40 CFR 51.308(g), these are “[r]equirements for periodic reports describing progress towards the reasonable progress goals.” While the URP to natural conditions, and the resulting URP milestone for 2018, is an important frame of reference, a state is required to report progress toward its RPG for 2018, not the URP milestone. CARB used the five-year period from 2007-2011 as the basis of comparison to the RPGs, which was the most current data available at the time of the analysis. CARB also included data on visibility conditions at each Class I area in 2012 in the appendices  to indicate further progress, even though this year is outside the time frame of the State's review. We do not agree that the Progress Report needs revision, because CARB has adequately addressed this particular requirement.
Comment: NPCA requested that EPA include the five-year rolling averages of species extinction in graphical and tabular form for each Class I area to illustrate more clearly the impact associated with each pollutant species. Further, NPCA suggested that EPA clearly include estimates of emission trends from relevant sources outside the State that impact California's Class I areas.
Response: The data on species extinction, while potentially informative, is not required by the Rule. As to emission trends of sources outside of California, this information is required in the progress reports from states in which those Class I areas are located. It is worth noting that CARB is required to address any significant changes in anthropogenic emissions within or outside the State that have impeded progress at its Class I areas under 51.308(g)(5), which is addressed further below.
D. Changes in Emissions
Comment: NPCA stated that the emissions inventory in the Report does not include natural sources, which are particularly important due to the role of wildfire in visibility impairment. NPCA requested that EPA include emissions from natural sources in the State's emissions inventory, including projected future values. NPCA further stated that it is unclear whether the emission inventory includes several other growing sources of anthropogenic emissions, including emissions from increased oil and gas production (e.g., from fracking and transportation of crude oil through California by rail). NPCA also noted that the Report did not discuss emissions of ammonia, a precursor to ammonium nitrate and ammonium sulfate, which impair visibility.
Response: CARB provides statewide emission inventories by source category and pollutant in five-year increments from 2000 to 2020 in the Emission Inventory 2013 Almanac (Appendix B of the Progress Report) that is used as the basis for reporting on emission inventories and trends, including the period from 2005 to 2010. In the context of reducing man-made impairment of visibility, EPA does not expect states to include wildfires in addressing this requirement. While developing an inventory of past wildfire emissions is possible, using this information to project future emissions is highly problematic given the variation in time and place as well as the inherent unpredictability of wildfire events. That said, CARB includes in its Progress Report  three case studies that provide a detailed analysis of the impact of documented wildfire events on specific Class I areas. While not appropriate for a trend analysis, this type of information is critical to understanding the effect of wildfires on visibility, especially in Class I areas where wildfires have limited progress toward achieving the RPGs for 2018.
CARB did include emissions from oil and gas production. Two source categories are listed for each of the four pollutants (NOX, SOX, volatile organic compounds (VOC), and particulate matter of 2.5 microns or less (PM2.5)) in the Emission Inventory 2013 Almanac. The first category, “Oil and Gas Production (Combustion),” is largely emissions from oil field equipment, which are mostly point sources. The second category, “Oil and Gas Production,” consists of evaporative emissions from sources like tanks and leaking valves, which are usually area sources. Another category, listed as “Off-Road Equipment,” includes emissions from drilling rigs. CARB's interactive emission inventory that was used for the Progress Report is available online at http://www.arb.ca.gov/app/emsinv/fcemssumcat2013.php.
It is difficult to determine whether the limited, minor increases in the Oil and Gas inventory are attributable to any increase in production. We consider any potential growth in this sector a prospective issue for the State to address in its next RH SIP revision due in 2018. Nonetheless, according to the Emission Inventory 2013 Almanac (Appendix B), the following trends are discernable:
- Oil and Gas Production (Combustion): For this category of oil and gas stationary sources, NOX emissions constitute the largest annual total (3,723 tpy in 2010) of the four pollutants listed in the State's inventory. However, these emissions are projected to decline from 2000 to 2020. SOX emissions from this category increased from 2005 to 2010 (475 to 767 tpy), but overall are projected to decline from 2000 to 2020. VOC emissions are relatively flat (949 tpy in 2005 and 2010). PM2.5, while also relatively flat from 2000 to a projected 2020, increased slightly from 2005 to 2010 (657 to 767 tpy).
- Oil and Gas Production: For this category of oil and gas area sources, VOCs constitute the largest annual total (13,615 tpy in 2010), but are projected to decline from 2000 to 2020. For the five-year period from 2005 to 2010, emissions of VOCs decreased about 11 percent from 15,367 to 13,615 tpy. These oil and gas area sources also emit NOX emissions, but at a lower level. Emissions of NOX are expected to decline from 2000 to 2020, including from 986 tpy in 2005 to 803 tpy in 2010. SOX emissions are consistently flat from 2000 to 2020 at about 36 tpy. PM2.5 emissions were 36 tpy in 2005 and are reportedly zero for 2010 and the inventory years thereafter.
Regarding ammonia, the RHR does not require the inclusion of ammonia in the emission inventory. In EPA's General Principles for developing the progress reports, we explained that “[b]ecause nearly all of the initial regional haze SIPs . . . considered only SO2, NOX, and PM as visibility impairing pollutants, the first five-year reports are usually not required to identify or quantify emission reductions for other pollutants, such as ammonia or VOC.”  Although not required, information exists regarding whether emissions of ammonia are an issue in California. For example, research by Start Printed Page 17330CARB  indicates that, due to the relative abundance of ammonia, reducing ammonia emissions are not as effective at reducing ammonium nitrate and ammonium sulfate as directly reducing NOX and SO2.
E. Anthropogenic Emissions Impeding Progress
Comment: NPCA acknowledged that California discusses the impacts of wildfire, off-shore shipping, and Asian dust, which have impeded progress in some of California's Class I areas. NPCA suggested that EPA do more research in these areas to develop nationally consistent methods to account for emissions from these types of sources. For example, the distinction between prescribed fires and wildfires is confusing in regard to what is natural versus anthropogenic and what is controllable versus uncontrollable given the interconnection between these two categories of fire. Similarly, NPCA encouraged EPA to address emissions from federally regulated sources and to consult with other countries on international sources of haze. NPCA restated its concern regarding the potential for increased emissions related to oil and gas development and production, as well as the importation of crude oil by rail. NPCA also addressed the indirect impacts of climate change on regional haze as warmer temperatures contribute to higher ground level ozone and PM2.5 concentrations.
Response: EPA acknowledges that more research and consistent methods are needed to understand and measure the effects of anthropogenic emissions from sources outside a state's control (e.g., emissions from Asia, Mexico, and Canada). Further research also is needed concerning the anthropogenic component of wildfires and prescribed fires, which is subject to interpretation, and varies over time and place. It is worth noting that the Federal government continues to regulate emissions from mobile and off-shore shipping, for example, which are credited in the RH SIPs. Moreover, we understand and share concerns about the potential effects of climate change on human health and the environment. We continually work with CARB and other air quality agencies in California to update and improve emission inventories in order to evaluate more accurately our progress in improving human health and the environment.
F. Meeting the Reasonable Progress Goals
Comment: NPCA is concerned that the progress that California appears to be making in most Class I areas may not be enforceable or permanent. NPCA encouraged EPA to revise downward the RPGs for 2018 to reflect the progress to date, noting that California has previously committed to reevaluating the RPGs to determine if they should be adjusted to better reflect achievable improvement.
Response: The purpose of the Progress Report is to evaluate whether the State's existing plan is making sufficient progress in achieving the established RPGs for 2018 in its 29 Class I areas, and is not interfering with the ability of other States to make similar progress in nearby Class I areas. The Rule does not make any provision for EPA to require a state to lower its RPGs where it appears from a progress report that they will be achieved.
G. Visibility Monitoring Strategy
Comment: NPCA encouraged EPA to maintain, and consider increasing, funding for the IMPROVE monitoring network, given that a number of California's Class I areas share monitors.
Response: EPA acknowledges NPCA's support for the IMPROVE monitoring network.
H. Determination of Adequacy
Comment: NPCA requested that EPA not approve California's determination of adequacy. NPCA cited the fact that the LAVO  monitoring data shows degradation of visibility on the worst days, and is therefore not on track to meet its RPG. This means that the SIP is not sufficient to meet the established visibility goals. NPCA also mentioned California's identification of wildfires, shipping emissions, and Asian dust as relatively significant factors, particularly in relation to the LAVO monitor.
Response: EPA disagrees with NPCA's request to disapprove the State's determination of adequacy. The requested disapproval is based on the commenter's interpretation that the LAVO monitoring data, representing three Class I areas in northern California, indicate that these Class I areas will not achieve the RPG by 2018. As we noted in our proposal, LAVO is the only monitor, based on the most recent five-year average (2008-2012), which shows worse visibility conditions (15.6 dv) compared to its baseline (14.1 dv). However, this situation in 2008-2012 does not necessarily mean that the SIP is not adequate to achieve the RPG by 2018, because wildfire smoke, a key contributor to haze in this period, should not be assumed to be the same in 2018 as during 2008-2012. We explained that “CARB provides technical analyses of how wildfire smoke can elevate the deciview value on a sufficient number of the 20 percent worst days to increase the annual average deciview as well as skew the five-year average deciview at a given monitor.”  In fact, CARB provides a technical analysis of the factors impeding progress at LAVO in its Progress Report. In particular, CARB establishes a positive correlation between documented wildfires in southern Oregon and northern California in 2008 and 2009 with exceptionally high readings of organic carbon at the LAVO monitor on worst days in those same years. CARB goes on to document that the worst day averages at the LAVO monitor for 2010 (12.8 dv), 2011 (11.7 dv), and 2012 (14.3 dv) were below or near the baseline average of 14.1 dv. Taking this evidence of wildfire impacts into consideration, the LAVO monitor establishes a trend toward meeting the RPG for 2018 of 13.3 dv. It is EPA's determination that CARB adequately demonstrates that no substantive revisions are needed at this time to achieve the established RPGs at the Class I areas.
III. Summary of Final Action
EPA is taking final action to approve the California Regional Haze Plan 2014 Progress Report submitted to EPA on June 16, 2014, as meeting the applicable RHR requirements as set forth in 40 CFR 51.308(g), (h), and (i). With 29 Class I areas in California, we commend CARB on the Progress Report, and in particular, the development of the case studies in Appendix D that provide an analysis of wildfire impacts at three of the IMPROVE monitors. The comprehensive evaluation of the California RH SIP due in 2018 for the next ten-year planning period is the next opportunity to reassess progress and make any necessary adjustments.Start Printed Page 17331
IV. Statutory and Executive Order Reviews
Under the CAA, the Administrator is required to approve a SIP submission that complies with the provisions of the Act and applicable Federal regulations. Thus, in reviewing SIP submissions, EPA's role is to approve state decisions, provided that they meet the criteria of the CAA. Accordingly, this action merely approves state law as meeting Federal requirements, and does not impose additional requirements beyond those imposed by state law. For that reason, this action:
- Is not a “significant regulatory action” subject to review by the Office of Management and Budget under Executive Order 12866 (58 FR 51735, October 4, 1993);
- does not impose an information collection burden under the provisions of the Paperwork Reduction Act (44 U.S.C. 3501 et seq.);
- is certified as not having a significant economic impact on a substantial number of small entities under the Regulatory Flexibility Act (5 U.S.C. 601 et seq.);
- does not contain any unfunded mandate or significantly or uniquely affect small governments, as described in the Unfunded Mandates Reform Act of 1995 (Pub. L. 104-4);
- does not have Federalism implications as specified in Executive Order 13132 (64 FR 43255, August 10, 1999);
- is not an economically significant regulatory action based on health or safety risks subject to Executive Order 13045 (62 FR 19885, April 23, 1997);
- is not a significant regulatory action subject to Executive Order 13211 (66 FR 28355, May 22, 2001);
- is not subject to requirements of Section 12(d) of the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 272 note) because this action does not involve technical standards; and
- does not provide EPA with the discretionary authority to address, as appropriate, disproportionate human health or environmental effects, using practicable and legally permissible methods, under Executive Order 12898 (59 FR 7629, February 16, 1994).
In addition, this rule does not have tribal implications as specified by Executive Order 13175 (65 FR 67249, November 9, 2000), because the SIP is not approved to apply on any Indian reservation land or in any other area where EPA or an Indian tribe has demonstrated that a tribe has jurisdiction. In those areas of Indian country, the rule does not have tribal implications and will not impose substantial direct costs on tribal governments or preempt tribal law as specified by Executive Order 13175.
The Congressional Review Act, 5 U.S.C. 801 et seq., as added by the Small Business Regulatory Enforcement Fairness Act of 1996, generally provides that before a rule may take effect, the agency promulgating the rule must submit a rule report, which includes a copy of the rule, to each House of the Congress and to the Comptroller General of the United States. EPA will submit a report containing this action and other required information to the U.S. Senate, the U.S. House of Representatives, and the Comptroller General of the United States prior to publication of the rule in the Federal Register. A major rule cannot take effect until 60 days after it is published in the Federal Register. This action is not a “major rule” as defined by 5 U.S.C. 804(2).
Under section 307(b)(1) of the Clean Air Act, petitions for judicial review of this action must be filed in the United States Court of Appeals for the appropriate circuit by June 1, 2015. Filing a petition for reconsideration by the Administrator of this final rule does not affect the finality of this action for the purposes of judicial review nor does it extend the time within which a petition for judicial review may be filed, and shall not postpone the effectiveness of such rule or action. This action may not be challenged later in proceedings to enforce its requirements (see section 307(b)(2)).Start List of Subjects
List of Subjects in 40 CFR Part 52
- Environmental protection
- Air pollution control
- Incorporation by reference
- Intergovernmental relations
- Nitrogen oxides
- Organic carbon
- Particulate matter
- Reporting and recordkeeping requirements
- Sulfur oxides
- Volatile organic compounds
Dated: February 27, 2015.
Regional Administrator, EPA Region IX.
Part 52, Chapter I, Title 40 of the Code of Federal Regulations is amended as follows:Start Part
PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANSEnd Part Start Amendment Part
1. The authority citation for Part 52 continues to read as follows:End Amendment Part
Subpart F—CaliforniaStart Amendment Part
2. Section 52.220 is amended by adding paragraph (c)(454) to read as follows:End Amendment Part
(c) * * *
(454) The following plan was submitted on June 16, 2014, by the Governor's Designee.
(ii) Additional materials.
(A) California Air Resources Board (CARB).
(1) CARB Resolution 14-15, dated May 22, 2014, approving the “California Regional Haze Plan 2014 Progress Report.”
(2) The “California Regional Haze Plan 2014 Progress Report”, adopted on May 22, 2014.
3. Section 52.281 is amended by adding paragraph (g) to read as follows:End Amendment Part
(g) Approval. On June 16, 2014, the California Air Resources Board submitted the “California Regional Haze Plan 2014 Progress Report” (“Progress Report”). The Progress Report meets the requirements of Clean Air Act sections 169A and 169B and the Regional Haze Rule in 40 CFR 51.308.
3. Letter from Nathan Miller (NPCA) to Thomas Webb (EPA) dated November 29, 2014.Back to Citation
6. California Regional Haze Plan 2014 Progress Report, CARB, May 22, 2014, pages 6-7.Back to Citation
7. WRAP Regional Haze Rule Reasonable Progress Report Support Document, Emissions Inventories, page 3-11 to 3-29.Back to Citation
8. NPCA letter to EPA dated November 29, 2014, page 8.Back to Citation
9. See Progress Report, Statewide 2018 Reasonable Progress Goals Summary, Table 3, page 12.Back to Citation
10. See Progress Report, Deciview Record (2000-2012), Appendix C, Tables C-1, C-2, and C-3.Back to Citation
11. Progress Report, Technical Analyses of Factors Impeding Progress, Appendix D, pages 1-23.Back to Citation
12. Progress Report, Appendix B.Back to Citation
13. General Principles for the 5-Year Regional Haze Progress Reports, USEPA, April 2013, page 7.Back to Citation
14. Proposed Revision to the PM2.5 State Implementation Plan for the San Joaquin Valley, Weight of Evidence Analysis, Appendix B, CARB, January 11, 2013, at http://www.arb.ca.gov/planning/sip/sjvpm25/24hrsjvpm25.htm.Back to Citation
15. LAVO is an IMPROVE monitor collecting air quality data for Lassen Volcanic National Park, Caribou Wilderness Area, and Thousand Lakes Wilderness Area in northern California.Back to Citation
17. Ibid.Back to Citation
18. Technical Analyses of Factors Impeding Progress, Appendix D, pages D8-D16.Back to Citation
19. See Figure D-7, Relative Contributions to Total Light Extinction at LAVO, Progress Report, page D-9.Back to Citation
20. Progress Report, page D-13.Back to Citation
[FR Doc. 2015-07232 Filed 3-31-15; 8:45 am]
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