Fish and Wildlife Service, Interior.
Proposed rule.
The best available scientific and commercial data indicate that the Concho water snake (
The Concho water snake is a reptile endemic to central Texas. It was listed as threatened on September 3, 1986, due to threats of habitat modification and destruction (51 FR 31412). Through implementation of recovery efforts, the Service has determined that this species has been recovered and no longer meets the definition of threatened or endangered.
Comments on the proposed rule must be received on or before September 8, 2008. Public hearing requests must be received by August 22, 2008.
You may submit comments by one of the following methods:
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We will post all comments on
Adam Zerrenner, Field Supervisor, U.S. Fish and Wildlife Service, Austin Ecological Services Field Office, 10711 Burnet Road, Suite 200, Austin, TX 78758; telephone 512/490–0057, extension 248; facsimile 512/490–0974. Persons who use a telecommunications device for the deaf (TDD) may call the Federal Information Relay Service (FIRS) at 800/877–8339, 24 hours a day, 7 days a week.
Our intent is to use the best available commercial and scientific data as the foundation for all endangered and threatened species classification decisions. Comments or suggestions from the public, other concerned governmental agencies, the scientific community, industry, or any other interested party concerning this proposed rule to delist the (species name) are hereby solicited. Comments particularly are sought concerning:
(1) Any threat (or lack thereof) to the Concho water snake;
(2) Additional information on the range, distribution, and location of any additional populations of the Concho water snake;
(3) Information on habitat destruction and/or preservation for the Concho water snake;
(4) Current or planned activities in the species' habitat and the possible impacts to the Concho water snake;
(5) Data on population trends;
(6) Data on the status of Concho water snakes in reservoirs;
(7) Information regarding the sufficiency of planned flows in the Colorado River to maintain habitat for the Concho water snake;
(8) Data on the need for movement of Concho water snakes around large dams to maintain genetic diversity; and
(9) Information pertaining to the design of the required post delisting monitoring.
You may submit your comments and materials concerning this proposed rule by one of the methods listed in the
Before including your address, phone number, e-mail address, or other personal identifying information in your comment, you should be aware that we will post your entire comment—including your personal identifying information—on
In making a final decision on this proposal, we will take into consideration the comments and any additional information we receive. Such communications may lead to a final rule that differs from this proposal.
Comments and materials we receive, as well as supporting documentation we used in preparing this proposed rule, will be available for public inspection on
The Act provides for one or more public hearings on this proposal, if requested. Requests must be received by August 22, 2008. Such requests must be made in writing and addressed to the Field Supervisor (see
The Concho water snake is endemic to the Colorado and Concho Rivers in central Texas (Tennant 1984, p. 344; Scott
At the time of listing, there were considered to be two subspecies of
In 1998, the Colorado River Municipal Water District (District) (1998, pp. 8–29) summarized 10 years of data collected on Concho water snake populations, status, and distribution. In 2004, the U.S. Geological Survey (USGS) analyzed capture-recapture data from 3 sources: (1) Mueller (1990, pp. 18–27); (2) Whiting (1993, Appendix 1); and (3) the 10 years of District data. However, for a number of reasons, primarily insufficient sampling effort at any single study site and a host of variables, especially environmental variability within a site and among sites, study results have not been robust enough to allow either population or trend estimates with satisfactory precision (Service 2004, p. 23). Additional information, particularly concerning the habitat requirements of the Concho water snake, is discussed under Summary of Factors Affecting the Species below.
The Concho water snake is characterized by being somewhat smaller than most other
Concho water snakes feed almost exclusively on fish (Williams 1969, pp. 9–10; Dixon
We classified the Concho water snake as threatened on September 3, 1986 (51 FR 31412). The primary reasons for listing were extensive habitat loss and imminent threats to a large portion of its remaining population. Critical habitat was designated on June 29, 1989 (54 FR 27377). In September 1993, we finalized a recovery plan for the Concho water snake (Service 1993). In June 1998, we received a petition to delist the Concho water snake from the District. On August 2, 1999, we published a 90-day petition finding that the petitioner did not present substantial information indicating that delisting the species may be warranted (64 FR 41903).
Section 4(f) of the Act directs us to develop and implement recovery plans for listed species unless the Director determines that such a plan will not benefit the conservation of the species. The Service completed the Concho Water Snake Recovery Plan in 1993. The Concho Water Snake Recovery Plan outlines recovery criteria to assist in determining when the snake has recovered to the point that the protections afforded by the Act are no longer needed (Service 1993, p. 33). These criteria are: (1) Adequate instream flows are assured even when the species is delisted. (2) Viable populations are present in each of the three major reaches (the Colorado River above Freese Dam, Colorado River below Freese Dam, and the Concho River). Here, population is defined as all Concho water snakes in a given area, in this case, each major river reach. (3)
We used the recovery plan to provide guidance to the Service, State of Texas, and other partners on methods to minimize and reduce the threats to the Concho water snake and to provide measurable criteria that would be used to help determine when the threats to the Concho water snake had been reduced so that it could be removed from the Federal List of Endangered and Threatened Wildlife.
Recovery plans in general are not regulatory documents and are instead intended to provide a guide on how to achieve recovery. There are many paths to accomplishing recovery of a species in all or a significant portion of its range. The main goal is to remove the threats to a species, which may occur without meeting all recovery criteria contained in a recovery plan. For example, one or more criteria may have been exceeded while other criteria may not have been accomplished. In that instance, the Service may judge that, overall, the threats have been reduced sufficiently, and the species is robust enough, to reclassify the species from endangered to threatened or perhaps to delist the species. In other cases, recovery opportunities may be recognized that were not known at the time the recovery plan was finalized. Achievement of these opportunities may be counted as progress toward recovery in lieu of methods identified in the recovery plan. Likewise, we may learn information about the species that was not known at the time the recovery plan was finalized. The new information may change the extent that criteria need to be met for recognizing recovery of the species. Overall, recovery of a species is a dynamic process requiring adaptive management. Judging the degree of recovery of a species is also an adaptive management process that may, or may not, fully follow the guidance provided in a recovery plan.
For more information on recovery of the Concho water snake, see the recovery plan at
A review of the best scientific and commercial data currently available (see Summary of Factors Affecting the Species section below) indicates that all three criteria in the Concho water snake recovery plan (adequate instream flows even after delisting, viable populations in each of the three major river reaches, and movement of snakes to assure adequate genetic mixing) have been met. Further, recovery of the Concho water snake has been a dynamic process, which has been furthered by the significant amount of new data collected on the biology and ecology of the species by numerous species experts. Since the time of listing and completion of the recovery plan, biologists have discovered that the snakes are able to persist and reproduce in the shorelines of reservoirs and that the snakes have managed to persist in all three population segments, surviving many years of drought. Based on this new information, the analysis below considers the best available data in determining that the Concho water snake may no longer meet the definition of a threatened or endangered species.
Section 4 of the Act and its implementing regulations (50 CFR part 424) set forth the procedures for listing, reclassifying, or removing species from listed status. “Species” is defined by the Act as including any species or subspecies of fish or wildlife or plants, and any distinct vertebrate population segment of fish or wildlife that interbreeds when mature (16 U.S.C. 1532(16)). Once the “species” is determined, we then evaluate whether that species may be endangered or threatened because of one or more of the five factors described in section 4(a)(1) of the Act. We must consider these same five factors in delisting a species. We may delist a species according to 50 CFR 424.11(d) if the best available scientific and commercial data indicate that the species is neither endangered nor threatened for the following reasons: (1) The species is extinct; (2) the species has recovered and is no longer endangered or threatened (as is the case with the (Concho water snake)); and/or (3) the original scientific data used at the time the species was classified were in error.
A recovered species is one that no longer meets the Act's definition of threatened or endangered. Determining whether a species is recovered requires consideration of the same five categories of threats specified in section 4(a)(1) of the Act. For species that are already listed as threatened or endangered, this analysis of threats is an evaluation of both the threats currently facing the species and the threats that are reasonably likely to affect the species in the foreseeable future following the delisting or downlisting and the removal or reduction of the Act's protections.
A species is “endangered” for purposes of the Act if it is in danger of extinction throughout all or a “significant portion of its range” and is “threatened” if it is likely to become endangered within the foreseeable future throughout all or a “significant portion of its range.” The word “range” in the phrase “significant portion of its range” (SPR) refers to the range in which the species currently exists. For the purposes of this analysis, we will evaluate whether the currently listed species, the Concho water snake, should be considered threatened or endangered throughout all of its range. Then we will consider whether there are any portions of the Concho water snake's range in which it is in danger of extinction or likely to become endangered within the foreseeable future.
For the purposes of this proposed rule, we consider “foreseeable future” for the Concho water snake to be 20 years. This is a reasonable timeframe for analysis of factors identified that could affect the species in the future and as they relate to Concho water snake biology. The snakes become sexually mature at 2 or 3 years old and reproduce annually (Werner and Dixon 2000, p. 216), with a likely life span rarely exceeding 5 years (Greene
The following analysis examines all five factors currently affecting, or that are likely to affect, the Concho water snake within the foreseeable future.
Concho water snakes are known to occur in rivers, streams, and along the artificial shoreline of reservoirs. These snakes are air-breathing; however, they feed almost exclusively on fish and are, therefore, found only near water sources capable of supporting at least a minimal fish population. Stream and river habitat used by the Concho water snake is primarily associated with riffles (Greene 1993, p. 96; Werler and Dixon 2000, p. 210; Forstner
In the reservoirs, Concho water snake habitat is most likely shallow water with minimal wave action and rocks along the shoreline (Scott
Adult and maturing Concho water snakes use a wider range of habitats than do juveniles (Scott
Historically the Concho water snake was known to occur in spotty distribution on the mainstem of the Colorado River below E.V. Spence Reservoir near the City of Robert Lee downstream to the F.M. 45 bridge and then not again until further downstream near the City of Bend (Tinkle and Conant 1961, pp. 42–43; Williams 1969, p. 3). On the Concho River and its tributaries, Concho water snakes were historically known from Spring Creek, Dove Creek, and the South Concho River, all upstream of the Twin Buttes Reservoir, and on the mainstem of the Concho River downstream from San Angelo to the confluence with the Colorado River (Marr 1944, pp. 486–487; Tinkle and Conant 1961, pp. 42–43). By the time the Concho water snake was federally listed, it had been extirpated from the tributaries above the City of San Angelo (Flury and Maxwell 1981, p. 31), and surveys had never located snakes in lakes or reservoirs (Scott and Fitzgerald 1985, pp. 17, 34). At the time of listing, the range of the snake included O.C. Fisher, Twin Buttes, and Spence reservoirs and one tributary creek reservoir, Ballinger Municipal Lake. A fifth reservoir, O.H. Ivie (formerly known as Stacy), was already planned for construction at the confluence of the Concho and Colorado Rivers and was expected to reduce the range of Concho water snakes by more than 50 percent (Scott and Fitzgerald 1985, pp. 31, 35).
By 1993, Scott
In 2004 and 2005, Drs. Forstner and Dixon surveyed for Concho water snakes across the species' range. One goal of Forstner
At the time of listing, we believed the construction of Ivie Reservoir would have two major impacts that would result in loss of Concho water snake
As a result of a 1986 formal consultation conducted under section 7 of the Act with the U.S. Army Corps of Engineers (USACE) on construction of Freese Dam to form Ivie Reservoir (1986 Biological Opinion), the District agreed to implement conservation measures that included, but were not limited to: Long-term monitoring of the snakes, completing life-history studies, maintaining specific flow regimes from Spence and Ivie reservoirs, creating six artificial riffles below Spence, and transplanting snakes between populations above and below Ivie Reservoir (Service 1986, pp. 12–24).
As part of their long-term monitoring plan, District field biologists conducted extensive searches for the Concho water snake beginning in 1987. According to Dixon
Additionally, during the District's 10-year monitoring effort (1987–1997), snakes were regularly found in Spence, Ivie, and Lake Ballinger Reservoirs, a habitat type they were not known to occupy at the time of listing. Concho water snakes have continued to be found in reservoirs. Dixon's (2004, pp. 3–4) surveys in 2004 confirmed that snakes persist in Spence and Ivie Reservoirs, and, while Ballinger Lake had only a small pool of water (2 feet or less) in 2004 and no snakes were found, after rains in 2005 Forstner
Because Concho water snakes are now known to be reproducing and persisting in lakes and reservoirs and their current distribution is larger than reported at the time of listing and historically, habitat loss from reservoir inundation is no longer believed to be a significant threat to the long-term survival of the species.
In severe drought, as the region has experienced over the last 15 years (TWDB 2006, 1–60, 1–67), the linear extent of dewatered riverine habitats could be large and the length of time without flows could extend for several months or more (Service 2004, p. 51). Decreased flow will likely reduce the amount of available shallow rocky habitats in much of the river. However, Concho water snakes appear able to survive these low flow periods. For example, Elm Creek had experienced a number of extended no flow periods over the 5 years prior to 2004 and then flooded in August 2004. In September 2004, Dixon (2004, p. 11) noted Concho water snakes inhabited the site. Dixon (2004, p. 12) surmised that snakes either moved from the mouth of Elm Creek at the Colorado River (a distance of 4.6 creek mi (7.4 creek km)), or existed in deep pools somewhere within a returnable distance to the site. Another example of snake persistence during dry times was the drying of Ballinger Lake in 2004 and confirmation of reproductive snakes in the lake in 2005 following rains (Dixon 2004, p. 4; Forstner
According to Dixon (2004, p. 9), during long periods of drought, the low-head dams (small private dams, a few feet tall, that create pools upstream and riffle-like areas downstream) within both the Concho and Colorado Rivers form pools that can extend two-thirds of a mile (1 km) or more up river (depending on dam height). The riffles and pools that lie upstream of these low-head dams may not completely dry up because of small springs and creeks nearby. These pools act as refuges for juvenile and adult Concho water snakes when flow ceases (Dixon 2004, p. 9). Concho water snakes have been located in pools behind low-head dams along the Colorado River, and Dixon (2004, p. 9) states that it is reasonable to expect the small pools behind low-head dams on the Concho River act in the same way. Even with the drought, water continues to flow over bedrock in some areas, and snakes have been observed foraging for fish in the diminished flow. The extent of solid bedrock in some of the riffle systems tends to maintain the nature of the riffle and does not allow vegetation to root and collect debris and silt (Dixon 2004, p. 9).
Another way the snakes may endure drying conditions is to use deep burrows. Greene (1993, pp. 89, 94) found Concho water snake hibernacula (shelters for hibernating snakes) within 19.7 ft (6 m) of water with a mean depth of 1.7 ft (0.52 m). Hibernacula types included crayfish burrows, rock ledges, debris piles, and concrete low water crossings for adults and loose embankments of rock and soil for juveniles. Dixon (2006, p. 2) stated that during droughts the snakes were possibly in the crayfish burrows, since they may retain moisture.
Even in light of the ongoing regional drought (TWDB 2006, pp. 1–60, 1–67), USGS stream gauges have registered four flood events greater than 400 cubic feet per second (cfs) below Spence Reservoir and six flood events greater than 1,000 cfs below Ivie Reservoir over the last 10 years. While both Dixon (2004, pp. 8–9) and Forstner
The Concho water snake has evolved and adapted for thousands of years through many documented long-term droughts (Forstner
As discussed above, at the time of listing, we believed the construction of Ivie Reservoir would curtail normal water flow and prevent floodwater scouring. Without such flooding, riffle habitat is lost as the rocky streambed becomes covered with silt. In their recent survey of the Concho water snake and its habitat, Forstner
Since issuance of the 1986 Biological Opinion and associated minimum flow requirements, stream flows throughout the range of the Concho water snake have declined considerably (Forstner
In July 2004, the USACE reinitiated formal consultation (Consultation Number 2–15–F–2004–0242) with the Service on the District's activities. Prior to completing the consultation, the District indicated through a letter (2004, pp. 1–2), and the USACE concurred via e-mail (2004, p. 1), that an emergency situation existed due to a limited water supply endangering public health and safety to their municipal customers (450,000 people). The ongoing drought and implementation of the conditions in the 1986 Biological Opinion were given as the basis for this emergency. During the emergency, the District was allowed to cease releasing minimum flows, while formal consultation was ongoing. An amended biological opinion (2004 Biological Opinion) was completed in December 2004. Shortly thereafter, the District and the USACE determined the emergency had ended and the requirements of the amended Biological Opinion went into effect (Service 2004, pp. 1, 3). The main component of the 2004 Biological Opinion was a reduction in minimum flow requirements (Service 2004, pp. 11–12). The new flow requirements included, to the extent there is inflow into Spence Reservoir, that the District will maintain a minimum flow in the Colorado River downstream of not less than 4.0 cfs (0.11 cms) during April through September and 1.5 cfs (0.04 cms) during the months of October through March.
While the reduced minimum flows outlined in the 2004 Biological Opinion will have an impact on the aquatic habitat conditions in the Colorado River, those impacts will be ameliorated to some degree by the nature of the intervening watersheds that drain each of these stream segments, since both the Colorado and Concho rivers are gaining streams (Service 2004, pp. 50–51). Gaining streams gather water as you progress downstream. This gathering of water is exhibited not only by tributary inflow but also as bank discharge from spring flow that occurs where shallow aquifers interface with the stream. This gaining stream phenomenon is greatly controlled by ambient weather conditions. During periods of long-term drought, the tributaries and springs will cease flowing; however, during normal rainfall periods, these sources of water help to restore and maintain more stable instream flows in the mainstem (Service 2004, p. 50). Additionally, even when releases from dams have ceased, normal seepage from a dam occurs and provides for the formation of pools (large and small) that can provide habitat for the Concho water snake and the fish it preys upon for varying periods of time depending on ambient weather conditions. When dam releases are resumed, the pools (located below dams and up and downstream from spring areas) that may have served as refugial habitat are reconnected by flowing water.
If the Concho water snake is delisted, the minimum flow requirements required by the 2004 Biological Opinion will no longer apply. However, in February 2008 the Service entered into a MOU with the District to provide for the maintenance of these minimum flow releases in perpetuity. The purpose of the MOU is for the District to provide assurance that minimum reservoir releases will continue in perpetuity, consistent with the 2004 BO (Service, 2004, pp. 11–12). The releases will be maintained, to the extent there is inflow, if the Concho water snake is removed from the Federal list of threatened species. While this means the District has the authority to further reduce or even terminate flows during times of extremely low inflow, earlier analysis using 10 years of historical data indicated that, based on studies that demonstrate persistence of the snake in the past, such low flows occurring only occasionally and temporarily should not affect the snake's long-term status.
The District has implemented every activity requested by the Service in previous biological opinions beginning in 1986. The minimum flows required in the 2004 Biological Opinion have been implemented by the District and those flow requirements were duplicated in the 2008 MOU signed by the District. The District has an excellent track record of carrying out conservation actions to benefit the Concho water snake (Freese and Nichols 2006, Service pp. 42–47). The Service is
In addition to the MOU, and the 2004 Biological Opinion, Texas water law requirements also result in maintenance of instream flow. Texas observes traditional appropriative water rights, which is also known as the “first in time, first in right” rule (See Texas Water Code § 11.027). The state's water policy requires the Texas Commission on Environmental Quality (TCEQ) to set, to the extent practicable, minimum instream flows to protect the state's water quality when issuing water rights permits (See Texas Water Code § 11.0235(c)). Furthermore, Texas water law prohibits the owner of stored water from interfering with water rights holders downstream or releasing water that will degrade the water flowing through the stream or stored downstream (Texas Water Code § 297.93).
The District's water rights permit (TCEQ permit #3676) requires the District to maintain flows below Ivie Reservoir of 8 cfs from April through September and 2.5 cfs from October through March. Flows must be maintained below both Spence and Ivie reservoirs to ensure water quality and provide for downstream water rights. Flows are mandated and releases from Spence Reservoir are periodically required by the State of Texas to ensure the quality of water entering Ivie Reservoir. Spence Reservoir is known to be high in dissolved solids and chlorides (Service 2004, p. 6), so if flows into Spence Reservoir are low, water quality in the reservoir can become degraded unless flushing flows are released. The District must also ensure that senior water right holders are delivered specific amounts of water from Ivie Reservoir. Therefore, long-term low flow releases or no releases from Spence and Ivie Reservoirs are rare.
The District has been able to maintain flows from both Spence and Ivie reservoirs over the long term as evidenced by long-term measures of flows at two gages. Daily median flows in the reach of the Colorado River below Spence Reservoir (as measured at USGS near Ballinger since Spence Reservoir was constructed, 1969–2007) exceeded 4.0 cfs in the summer (April through September) all but 12 days. During the winter (October through March), daily median flows always exceeded 1.5 cfs. Daily median flows in the reach of the Colorado River below Ivie Reservoir (as measured at USGS at Winchell since Ivie Reservoir was constructed, 1990–2007) exceeded 8.0 cfs in the summer (April through September) all but 15 days. During the winter (October through March), daily median flows always exceeded 2.5 cfs. We believe that the District will continue to maintain instream flows in the foreseeable future.
While instream flows have decreased, Concho water snakes have continued to be found throughout their range. In addition, as discussed above in the Drought section, Concho water snakes appear to be able to survive low flow situations. Therefore, because the snakes have survived under low-flow conditions, and because some minimal flows will persist throughout parts of the snake's range (Forstner
Salt cedar (Tamarisk sp.) is a nonnative species that was introduced to the United States in the 1800s from southern Europe or the eastern Mediterranean region (DiTomaso 1998, p. 326). In the watersheds of the Spence and Ivie Reservoirs, these plants are abundant and have been reported to have greatly affected water quality and quantity because they consume large volumes of water and then transport salts from the water to the surfaces of their leaves. When the leaves are dropped in the fall, the salt is concentrated at the soil surface (Freese and Nichols 2006, p. 5.5; DiTomaso 1998, p. 334).
In an effort to increase water yield and reduce salt concentrations in Spence and Ivie reservoirs, the District, in cooperation with the Texas Cooperative Extension, the Texas Department of Agriculture, the U.S. Department of Agriculture—Agricultural Research Service, and the Texas State Soil and Water Conservation Board (TSSWCB), has initiated a salt cedar control project in the Upper Colorado River Basin, which includes spraying an herbicide to eradicate mass concentrations of salt cedar and then using a leaf beetle for biological control of new plant growth (Freese and Nichols 2006, p. 6.4). This project “is an excellent first step in the recovery of the Upper Colorado River Basin back to many of its [pre-infestation] functions, including native riparian habitat for wildlife and improved habitat for fish and other aquatic organisms,” and is “one of the most crucial options for improving water quality and quantity” (Freese and Nichols 2006, pp. 6.5–6.6). We have no information that the herbicide poses a direct poisoning threat to the Concho water snake.
Additionally, control programs for invasive brush species, such as juniper (
At the time of listing, we believed construction of Ivie Reservoir (formed by Freese Dam) would likely segment Concho water snakes into three separate populations and thereby reduce genetic exchange (Scott and Fitzgerald 1985, p. 34). Prior to the snake's listing in 1986, no researchers had documented Concho water snakes traveling over land to circumvent the barriers caused by large dams, and snakes had not been located in reservoirs. Due to this separation, a reasonable and prudent measure in the 1986 Biological Opinion was to transfer snakes annually between the populations separated by the dam. Snakes were transferred in 1995 and again in 2006 (District 1995, p. 1; District 2006, pp. 1–3).
Because we now know Ivie Reservoir, which receives flow from both the Concho and Colorado Rivers, to be occupied, we believe it is reasonable to surmise that snakes are capable of genetic interchange between the Concho and Colorado Rivers via the reservoirs' shorelines. The District (1998, p. 14) summarized Concho water snake habitat within Ivie Reservoir and found that
In recent surveys, Forstner
At the time of listing, we believed buildup of algae in riffle areas reduced oxygen and nutrients available to populations of fish, the Concho water snake's primary food (51 FR 31419). We were also concerned that the inflow of nutrients into the Concho River in the San Angelo area, along with reduced dilution capability associated with lower flows, created large concentrations of algae in portions of the river (51 FR 31419). A summary of the 1987–1996 fish collections in the Colorado and Concho Rivers, included in the Service's 2004 Biological Opinion (Appendix A, pp. 68–69), suggested that fish populations have persisted despite the presence of algae. Also, no impacts to snakes have been observed or documented as a result of water quality conditions during the ongoing drought (Service 2004, p. 52). Additionally, according to Dixon (2006, p. 2), Concho water snakes have been documented to survive in captivity for as long as 12 months with a reduced food supply. Therefore, we no longer consider algal growth and nutrient enrichment to be significant threats to the snake's survival.
The Concho water snake was listed as endangered by the State of Texas in 1984. In 2000, it was removed from the State's list of threatened species (TPWD 2000, p. 3) because TPWD no longer considered it likely to become endangered (64 FR 41903).
The Texas State Legislature implemented the Texas Clean Rivers program in 1991. The District has actively participated in the program since that time and monitors surface water quality in the upper Colorado River basin, which includes the distribution of the Concho water snake above Freese Dam. The Lower Colorado River Authority (LCRA) has the responsibility for water quality monitoring below Freese Dam. Both of these entities have participated in the Clean Rivers Program since 1991 and have provided a proactive response for ensuring a high level of surface water quality in the Colorado River and its mainstem reservoirs. These programs are ongoing and designed to ensure water quality integrity for all aquatic resources, including the Concho water snake and fish, its primary food source, in the upper basin. As water quality problems are detected, swift responses by the District and LCRA to effect corrective actions through State of Texas regulatory agencies (TCEQ and the Texas Railroad Commission) are completed (Service 2004, pp. 52–53).
Additional water quality protections for Concho water snakes in riverine and reservoir habitats will continue indirectly under the Clean Water Act (CWA). According to the Environmental Protection Agency (2006, p. 1), the CWA establishes basic structures for regulating discharges of pollutants into United States waters, protecting water quality for species dependent on rivers and streams for their survival.
According to species experts, minimally maintained, “mandated flows below Ivie Reservoir (TCEQ permit #3676) [and] senior water rights below both Spence and Ivie reservoirs” will adequately provide instream flows for the Concho water snake (Forstner
At the time of listing, we believed that declining flows, inundation, pollution, and other habitat threats would have adverse impacts on riffle-dwelling fish, the principal food of the Concho water snake (Williams 1969, pp. 9–10; Dixon
In conclusion, over the course of 20 years, including the construction of three dams that were anticipated to fragment the distribution of the Concho water snake, a prolonged drought accompanied by extreme low water flows in parts of the snake's range, and concerns about heavy nutrient inflows, surveys have confirmed that the snakes have occupied habitat along the new lakeshores, survived in or quickly reoccupied areas of extreme low flows, and have not been adversely affected by nutrient-related effects. Additionally, habitat restoration efforts such as the removal of salt cedar and other brushy species may be improving instream habitat for the Concho water snake and other aquatic species. We believe that destruction, modification, or curtailment of the Concho water snake habitat or range due to habitat loss, altered instream flows and floodwater scouring, drought, vegetation encroachment, fragmentation, and pollution no longer threaten the Concho water snake with becoming endangered.
Forstner (2006 p. 12) cites Soule's 1987 definition that describes the key criteria for a viable population to include the ability of the population to be self sustaining, able to persist over time (a century or longer for the Concho water snake), and the ability to adapt to local conditions and evolutionary pressures. Forstner stated that the criteria of self sustaining, seemingly viable populations in the Concho and Colorado rivers at the end of a decade of monitoring have been met. Recalling the three recovery criteria from the 1993 Concho Water Snake Recovery Plan: Adequate instream flows, viable populations in each of the three major reaches (as indicated by not only the repeated presence of snakes at long-term monitoring sites, but by documented evidence of reproduction as a measure
At the time of listing, Concho water snakes were known to sometimes be captured or killed by recreationists (51 FR 31420). The effect of this activity on Concho water snake populations was and still is believed to be minimal. However, instances of Concho and Brazos water snakes being killed have been reported in both populated and unpopulated areas. For example, Brazos water snakes have been crushed under stones at the water's edge by people walking on the banks and shot by small caliber firearms, and fishermen have commented on their success in removing the “water moccasins” from the river (Forstner
While some limited killing of snakes is likely still occurring, there is no evidence indicating that these mortalities are affecting the species on a rangewide or population level. Therefore, we find that mortality from this factor is not likely to cause the species to become threatened or endangered in the foreseeable future.
At the time of listing, no problems of disease or predation on Concho water snakes were known to exist (51 FR 31420). While currently no disease problems are known, predators on Concho water snakes have been identified. As is true for most snakes, predation is considered a major natural source of mortality for Concho water snakes (Werler and Dixon 2000, p. 215). Predators documented to prey on Concho water snakes include kingsnakes (
Due to the Texas Clean Rivers program, other Texas water law requirements, and the 2008 MOU between the Fish and Wildlife Service and the ASACE, both discussed earlier under Factor A, we believe that inadequacy of existing regulatory mechanisms does not constitute an ongoing threat to the Concho water snake.
We are unaware of any other natural or manmade factors affecting the continued existence of the Concho water snake at this time.
As required by the Act, we considered the five potential threat factors to assess whether the Concho water snake is threatened or endangered throughout all or a significant portion of its range. When considering the listing status of the species, the first step in the analysis is to determine whether the species is in danger of extinction throughout all of its range. If this is the case, then the species is listed in its entirety. For instance, if the threats on a species are acting only on a portion of its range, but they are at such a large scale that they place the entire species in danger of extinction, we would list the entire species.
Since the time of listing, it has been shown that: (1) Concho water snakes can survive lower flows than previously thought necessary for their survival; (2) mandated flows, downstream senior water rights, and the 2008 MOU between the District and the Service virtually assure maintenance of adequate instream flows; (3) viable populations of Concho water snakes exist in all three reaches of the species' range; (4) the snake uses the shoreline of reservoirs; (5) snakes may not need to be transferred between populations in order to prevent genetic isolation, although the 2008 MOU provides for them to be moved; and (6) it persists, reproduces, and remains viable throughout its range. In addition, the removal of salt cedar and other invasive brushy species is restoring riparian habitat, small riffles, and water quality for the Concho water snake.
The 1993 Recovery Plan described maintenance of adequate instream flows (Recovery Criterion 1) to maintain both the quantity and quality of Concho water snake habitat so that occupied habitat would continue to support viable populations of the species. At the time the recovery plan was completed, adequate instream flow rates were based on the constituent elements identified in the 1989 critical habitat designation (54 FR 27382) and the reasonable and prudent alternatives identified in the
(1) Lower flow rates support the snake population;
(2) Information on the snake's habitat indicates that they are more of a generalist and do not depend on the previously accepted narrow habitat requirements; and
(3) Adequate flow to maintain the snake's habitat and the snake population is provided by a variety of sources in addition to the flow required by the 2004 Biological Opinion (and subsequently required in a 2008 Memorandum of Understanding (MOU)).
As discussed above, in 2004, we revised the biological opinion and determined that lower flow rates were adequate to support riverine habitat for the snake. This was based on new information from numerous studies funded by the District in the 1990s that greatly added to our knowledge of the biology of the snake and its habitat. Monitoring of the snake population indicated that the population was sustained by the lesser flows required in the 2004 Biological Opinion (Forstner 2006, p. 12).
It is now known that the Concho water snake is more of a habitat opportunist than originally believed (Dixon 2004). In addition to riverine habitat, the snake is known to use areas above and below low head dams, pools created by the dams, man-made lakes, naturally occurring pools in the river, and tributaries, as Concho water snake has been found in Elm Creek and two of its tributaries. Further analysis by Forstner
While riverine habitat is important for the conservation of the snake, the need to maintain continuous flows at levels previously required were determined to no longer be necessary to provide adequate habitat for snakes. The flows described in the Recovery Plan and the specific flows included in the 1989 critical habitat designation were based on the best scientific information at that time; however, subsequent information provided by Forstner, Dixon, and Thornton indicated that the snake survived, reproduced, and maintained population viability with less stream flow. In response to that new information, the Service required lower stream flows in the 2004 Biological Opinion and based that decision on the continued population viability of the water snake (including snake abundance and reproductive success). This was further confirmed by the Fortner
In order to maintain riverine habitats in the Colorado River, we entered into a MOU in 2008 to ensure that the District will operate Colorado River reservoirs to provide adequate instream flows if the species were delisted, consistent with the 2004 Biological Opinion (see Factor A section above for more information).
In addition to the MOU, the District also maintains flows below Spence and Ivie reservoirs to ensure water quality and provide for downstream water rights. Flows are mandated and releases from Spence Reservoir are periodically required by the State of Texas to ensure the quality of water entering Ivie Reservoir. Spence Reservoir is known to be high in dissolved solids and chlorides (Service 2004, p. 6), which results in period releases of water from Spence Reservoir to maintain its water quality. The District must also ensure that senior water right holders are delivered specific amounts of water from Ivie Reservoir. Therefore, long term low flow releases or no releases from Spence and Ivie Reservoirs are not common practices unless an emergency situation occurs.
The Recovery Plan also required maintaining viable populations of the snake (Recovery Criterion 2). Forstner
The Recovery Plan also discussed the movement of Concho water snakes to counteract adverse impacts of population fragmentation and prescribed the movement of four snakes (two of each sex) every five years in a specific pattern above and below Ivie Reservoir (Recovery Criterion 3). The 2004 Biological Opinion discussed population fragmentation (Service 2004, p. 52) and changed the specific requirement for snake movements to five male water snakes above and below both the Robert Lee and Freese Dams once every three years. The Service believes that these movements are sufficient to maintain genetic heterogeneity between the separated populations. The 2008 MOU requires the same movements of snakes by the District even after the species is delisted. The Service based its belief and change in snake movement requirements on information available from monitoring and capture and release data after the preparation of the Recovery Plan.
As a result of the new information discussed above, it is our belief that the Recovery Plan's criteria for recovery of the species have been met.
Having determined that the Concho water snake no longer meets the definition of threatened or endangered, we must next consider whether there are any significant portions of its range that are in danger of extinction or are likely to become endangered in the foreseeable future. On March 16, 2007, a formal opinion was issued by the Solicitor of the Department of the Interior, “The Meaning of ‘In Danger of Extinction Throughout All or a Significant Portion of Its Range’ ” (U.S. DOI 2007). We have summarized our interpretation of that opinion and the underlying statutory language below. A portion of a species' range is significant if it is part of the current range of the species and is important to the conservation of the species because it contributes meaningfully to the representation, resiliency, or redundancy of the species. The contribution must be at a level such that its loss would result in a decrease in the ability to conserve the species.
The first step in determining whether a species is threatened or endangered in a significant portion of its range is to identify any portions of the range of the species that warrant further consideration. The range of a species can theoretically be divided into portions in an infinite number of ways. However, there is no purpose to analyzing portions of the range that are not reasonably likely to be significant and threatened or endangered. To identify only those portions that warrant
If we identify any portions that warrant further consideration, we then determine whether in fact the species is threatened or endangered in any significant portion of its range. Depending on the biology of the species, its range, and the threats it faces, it may be more efficient in some cases for the Service to address the significance question first, and in others the status question first. Thus, if the Service determines that a portion of the range is not significant, the Service need not determine whether the species is threatened or endangered there; conversely, if the Service determines that the species is not threatened or endangered in a portion of its range, the Service need not determine if that portion is significant.
The terms “resiliency,” “redundancy,” and “representation” are intended to be indicators of the conservation value of portions of the range. Resiliency of a species allows the species to recover from periodic disturbance. A species will likely be more resilient if large populations exist in high-quality habitat that is distributed throughout the range of the species in such a way as to capture the environmental variability within the range of the species. It is likely that the larger size of a population will help contribute to the viability of the species. Thus, a portion of the range of a species may make a meaningful contribution to the resiliency of the species if the area is relatively large and contains particularly high-quality habitat or if its location or characteristics make it less susceptible to certain threats than other portions of the range. When evaluating whether or how a portion of the range contributes to resiliency of the species, it may help to evaluate the historical value of the portion and how frequently the portion is used by the species. In addition, the portion may contribute to resiliency for other reasons—for instance, it may contain an important concentration of certain types of habitat that are necessary for the species to carry out its life-history functions, such as breeding, feeding, migration, dispersal, or wintering.
Redundancy of populations may be needed to provide a margin of safety for the species to withstand catastrophic events. This does not mean that any portion that provides redundancy is a significant portion of the range of a species. The idea is to conserve enough areas of the range such that random perturbations in the system act on only a few populations. Therefore, each area must be examined based on whether that area provides an increment of redundancy that is important to the conservation of the species.
Adequate representation insures that the species' adaptive capabilities are conserved. Specifically, the portion should be evaluated to see how it contributes to the genetic diversity of the species. The loss of genetically based diversity may substantially reduce the ability of the species to respond and adapt to future environmental changes. A peripheral population may contribute meaningfully to representation if there is evidence that it provides genetic diversity due to its location on the margin of the species' habitat requirements.
Applying the process described above for determining whether a species is threatened in a significant portion of its range, we next addressed whether any portions of the range of the Concho water snake warranted further consideration. We concluded through the five-factor analysis, in particular Factor A that the existing or potential threats are consistent throughout its range, and there is no portion of the range where one or more threats is geographically concentrated. We believe that there are no small geographic areas where localized threats still exist. Because the low level of threats to the species is essentially uniform throughout its range, no portion warrants further consideration.
In summary, Concho water snakes can survive lower flows than previously thought necessary for their survival; mandated flows and downstream senior water rights virtually assure maintenance of instream flows; viable populations of Concho water snakes exist in all three reaches of the species' range. Based on the snake's use of reservoirs, persistence, reproduction, and viability throughout its range, we have determined that none of the existing or potential threats, either alone or in combination with others, are likely to cause the Concho water snake to become in danger of extinction within the foreseeable future throughout all or a significant portion of its range. We believe the Concho water snake no longer requires the protection of the Act, and, therefore, we are proposing to remove it from the Federal List of Endangered and Threatened Wildlife.
If made final, this rule would revise 50 CFR 17.11 (h) to remove the Concho water snake from the Federal List of Endangered and Threatened Wildlife. The prohibitions and conservation measures provided by the Act, particularly through sections 7 and 9, would no longer apply to this species. Federal agencies would no longer be required to consult with us to insure that any action they authorize, fund, or carry out may affect the Concho water snake. Critical habitat was designated for the Concho water snake on June 29, 1989 (54 FR 27377). If finalized, this rule would also revise 50 CFR 17.95(x) to remove the critical habitat designation.
The Office of Management and Budget (OMB) has determined that this rule is not significant under Executive Order 12866 (E.O. 12866). OMB bases its determination upon the following four criteria:
(a) Whether the rule will have an annual effect of $100 million or more on the economy or adversely affect an economic sector, productivity, jobs, the environment, or other units of the government.
(b) Whether the rule will create inconsistencies with other Federal agencies' actions.
(c) Whether the rule will materially affect entitlements, grants, user fees, loan programs, or the rights and obligations of their recipients.
(d) Whether the rule raises novel legal or policy issues.
Section 4(g)(1) of the Act requires the Service to implement a system, in cooperation with the States, to monitor for not less than 5 years the status of all species that have recovered and been removed from the lists of threatened and endangered wildlife and plants (50 CFR 17.11, 17.12). The purpose of this post-delisting monitoring (PDM) is to verify that the species remains secure from risk of extinction after it has been removed from the protections of the Act. We are to make prompt use of the emergency listing authorities under section 4(b)(7) of the Act to prevent a significant risk to the well being of any
The Service is developing a draft PDM plan in cooperation with the District and Texas Parks and Wildlife Department. We intend to publish a notice of availability of the draft plan in the
In accordance with our joint policy published in the
Executive Order 12866 requires each agency to write regulations that are easy to understand. We invite your comments on how to make this proposed rule easier to understand, including answers to questions such as the following: (1) Are the requirements in this proposed rule clearly stated? (2) Does the proposed rule contain technical language or jargon that interferes with the clarity? (3) Does the format of the proposed rule (grouping and order of sections, use of headings, paragraphing, etc.) aid or reduce its clarity? (4) Would the rule be easier to understand if it were divided into more (but shorter) sections? (5) Is the description of the proposed rule in the “Supplementary Information” section of the preamble helpful in understanding the document? (6) What else could we do to make the proposed rule easier to understand? Send a copy of any written comments about how we could make this rule easier to understand to: Office of Regulatory Affairs, Department of the Interior, Room 7229, 1849 C Street, NW, Washington, DC 20240. You also may e-mail the comments to this address:
This rule does not contain any new collections of information that require approval by OMB under the Paperwork Reduction Act. This rule will not impose recordkeeping or reporting requirements on State or local governments, individuals, businesses, or organizations. An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid OMB control number.
We have determined that an Environmental Assessment or an Environmental Impact Statement, as defined under the authority of the National Environmental Policy Act of 1969, need not be prepared in connection with regulations adopted pursuant to section 4(a) of the Act. We published a notice outlining our reasons for this determination in the
A complete list of all references cited herein is available upon request from the U.S. Fish and Wildlife Service, Austin Ecological Services Field Office (see
The primary authors of this document are staff located at the Austin Ecological Services Field Office (see
Endangered and threatened species, Exports, Imports, Reporting and recordkeeping requirements, and Transportation.
Accordingly, we propose to amend part 17, subchapter B of chapter I, title 50 of the Code of Federal Regulations, as set forth below:
1. The authority citation for part 17 continues to read as follows:
16 U.S.C. 1361–1407; 16 U.S.C. 1531–1544; 16 U.S.C. 4201–4245; Pub. L. 99–625, 100 Stat. 3500; unless otherwise noted.
2. Section 17.11(h) is amended by removing the entry “Snake, Concho water” under “REPTILES” from the List of Endangered and Threatened Wildlife.
3. Amend section 17.95(c) by removing the critical habitat entry for “Concho water snake,