Federal Register: June 29, 2009 (Volume 74, Number 123)

DOCID: fr29jn09-22 FR Doc E9-15236

Veterans Affairs Department

CFR Citation: 50 CFR Part 17

RIN ID: RIN 1018-AU88

FWS ID: [FWS-R4-ES-2008-0104; MO 9221050083]

NOTICE: Part II

DOCID: fr29jn09-22

DOCUMENT ACTION: Proposed rule.

SUBJECT CATEGORY:

Endangered and Threatened Wildlife and Plants; Proposed Endangered Status for the Georgia Pigtoe Mussel, Interrupted Rocksnail, and Rough Hornsnail with Critical Habitat

DATES: We will accept comments received on or before August 28, 2009. We must receive requests for public hearings, in writing, at the address shown in the FOR FURTHER INFORMATION CONTACT section by August 13, 2009.

DOCUMENT SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), propose to list the Georgia pigtoe mussel (Pleurobema hanleyianum), interrupted rocksnail (Leptoxis foremani), and rough hornsnail (Pleurocera foremani), as endangered species under the Endangered Species Act of 1973, as amended (Act). The Georgia pigtoe, interrupted rocksnail, and rough hornsnail are endemic to the Coosa River drainage within the Mobile River Basin of Alabama, Tennessee, and Georgia. These three species have disappeared from large portions of their natural ranges due to extensive construction of dams that eliminated or reduced water currents and caused changes in habitat and water quality. The surviving populations are small, localized, and highly vulnerable to water quality and habitat deterioration.

We are also proposing to designate critical habitat concurrently for the Georgia pigtoe, interrupted rocksnail, and rough hornsnail under the Act. In total, approximately 258 kilometers (km) (160 miles (mi)) of stream and river channels fall within the boundaries of the proposed critical habitat designation for the three species: 153 km (95 mi) for the Georgia pigtoe, 101 km (63 mi) for the interrupted rocksnail, and 27.4 km (17 mi) for the rough hornsnail. The proposed critical habitat is located in Cherokee, Clay, Coosa, Elmore, and Shelby Counties, Alabama; Gordon, Floyd, Murray, and Whitfield Counties, Georgia; and Bradley and Polk Counties, Tennessee.

These proposals, if made final, would implement Federal protection provided by the Act.

SUMMARY:

Interior Department, Fish and Wildlife Service

SUPPLEMENTAL INFORMATION

Public Comments

We intend that any final action resulting from this proposal will be as accurate and as effective as possible. Therefore, we are seeking comments or suggestions from the public, other concerned governmental agencies, the scientific community, industry, or any other interested party concerning this proposed rule. We particularly seek comments concerning:
(1) Any biological, commercial trade, or other relevant data concerning any threat (or lack thereof) to the Georgia pigtoe mussel, interrupted rocksnail, and rough hornsnail;
(2) Any additional information concerning the ranges,
distributions, and population sizes of the species;
(3) Land use designations and current or planned activities in the subject area and their possible impacts on these species or proposed critical habitats;
(4) The reasons why any area should or should not be designated as critical habitat as provided by section 4 of the Act (16 U.S.C. 1531 et seq.), including whether the benefit of designation would outweigh threats to the species caused by designation such that the designation of critical habitat is prudent;
(5) Specific information on the amount and distribution of habitat for the Georgia pigtoe, interrupted rocksnail, and rough hornsnail, including areas occupied at the time of listing and containing the features essential to the conservation of the species, and areas not occupied at the time of listing that are essential to the conservation of the species and why;
(6) Any foreseeable economic, national security, or other potential impacts resulting from the proposed designation and, in particular, any impacts on small entities, and information about the benefits of including or excluding any areas that exhibit those impacts; and (7) Whether our approach to designating critical habitat could be improved or modified in any way to provide for greater public participation and understanding, or to assist us in accommodating public concerns and comments.

You may submit your comments and materials concerning this proposed rule by one of the methods listed in the ADDRESSES section. We will not accept comments you send by email or fax or to an address not listed in the ADDRESSES section.

We will post your entire commentincluding your personal identifying informationon http://www.regulations.gov. If you provide personal identifying information in addition to the required items specified in the previous paragraph, such as your street address, phone number, or email address, you may request at the top of your document that we withhold this information from public review. However, we cannot guarantee that we will be able to do so.

Comments and materials we receive, as well as supporting documentation we used in preparing this proposed rule, will be available for public inspection on http://www.regulations.gov, or by appointment, during normal business hours, at the U.S. Fish and Wildlife Service, Mississippi Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT).
Background

Georgia Pigtoe Mussel

The Georgia pigtoe (Pleurobema hanleyianum) is a freshwater mussel in the family Unionidae. It was described in 1852 by I. Lea as Unio hanleyianum from the Coosawattee River in Georgia. It was placed in the genus Pleurobema by Simpson in 1900. The uniqueness of the Georgia pigtoe has been verified both morphologically (Williams et al. 2008, p. 533) and genetically (Campbell et al. 2008, pp. 719721).

The shell of the Georgia pigtoe reaches about 50 to 65 millimeters (mm) (2 to 2.5 inches (in)) in length. It is oval to elliptical and somewhat inflated. The posterior ridge is low and evenly
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rounded when evident. The anterior end is rounded, while the posterior margin is bluntly pointed below. Dorsal and ventral margins are curved, and the beaks rise slightly above the hinge line. The periostracum (membrane on the surface of the shell) is yellowishtan to reddish brown and may have concentric green rings. The beak cavity is shallow, and the shell interior is white to dull bluishwhite (Parmalee and Bogan 1998, p. 185; Williams et al. 2008, p. 533).

Little is known about the habitat requirements or life history of the Georgia pigtoe; however, it is found in shallow runs and riffles with strong to moderate current and coarse sandgravelcobble bottoms. Unionid mussels, such as the Georgia pigtoe, filterfeed on algae, detritus, and bacteria from the water column. The larvae of most unionid mussels are parasitic, requiring a period of encystment on a fish host before they can develop into juvenile mussels. The fish host and glochidia (parasitic larvae) of Georgia pigtoe are currently unknown.

The Georgia pigtoe was historically found in large creeks and rivers of the Coosa River drainage of Alabama, Georgia, and Tennessee (Johnson and Evans 2000, p. 106; Williams et al., 2008, p. 534). There are historical reports or museum records of the Georgia pigtoe from Tennessee (Conasauga River in Polk and Bradley Counties), Georgia (Conasauga River in Murray and Whitfield Counties, Chatooga River in Chatooga County; Coosa River in Floyd County, Etowah River in Floyd County), and Alabama (Coosa River in Cherokee County, Terrapin Creek in Cherokee County, Little Canoe and Shoal Creeks in St. Clair County, Morgan Creek in Shelby County, and Hatchet Creek in Coosa County) (Florida Museum of Natural History Malacology Database (FLMNH) 2006; Gangloff 2003, p. 45). Based on these historical records, the range of the Georgia pigtoe included more than 480 km (300 mi) of river and stream channels. Additional historical Coosa River tributary records credited to Hurd (1974, p. 64) (for example, Big Wills, Little Wills, Big Canoe, Oothcalooga, Holly Creeks) have been found to be misidentifications of other species (M. Gangloff in litt. 2006).

In 1990, the Service initiated a status survey and review of the molluscan fauna of the Mobile River Basin (Hartfield 1991, p. 1). This led to extensive mollusk surveys and collections throughout the Coosa River drainage (Bogan and Pierson 1993a, pp. 127; P. Hartfield in litt. 19902001). At all localities surveyed in the Coosa River drainage, the freshwater mussel fauna had declined from historical levels, and at all but a few localized areas, the fauna proved to be completely eliminated or severely reduced due to a variety of impacts, including point and nonpoint source pollution, and channel modifications such as impoundment. Following a review of these efforts and observations, the Service reported 14 species of mussels in the genus Pleurobema, including the Georgia pigtoe, as presumed extinct, based on their absence from collection records, technical reports, or museum collections for a period of 20 years or more (Hartfield 1994, p. 1).

The Service and others continued to conduct surveys in the Coosa River drainage for mollusks (P. Hartfield in litt. 19902001; Williams and Hughes 1998, pp. 26; Johnson and Evans 2000, p. 106; Herod et al. 2001, pp iii; Gangloff 2003, pp. 1112; McGregor and Garner 2004, pp. 118; Johnson et al. 2005, p. 1). Several freshly dead and live individuals of the Georgia pigtoe were collected during these mussel surveys in the Upper Conasauga River, Murray and Whitfield Counties, Georgia (Williams and Hughes 1998, p. 10; Johnson and Evans 2000, p. 106). Gangloff (2003, pp. 1112, 45) conducted mussel surveys of Coosa River tributaries in Alabama, including all known historical collection sites for the Georgia pigtoe, without relocating the species. McGregor and Garner (2004, p. 8) surveyed the Coosa River dam tailraces for mollusks without encountering the Georgia pigtoe.

The Georgia pigtoe is currently known from a few isolated shoals in the Upper Conasauga River in Murray and Whitfield Counties, Georgia, and in Polk County, Tennessee (Johnson and Evans 2000, p. 106; Evans 2001, pp. 3334). All recent collection sites occur within a 43km (27 mi) reach of the river. Within this reach, the Georgia pigtoe is very rare (Johnson and Evans 2000, p. 106), and no population estimates are available.

Interrupted Rocksnail

The interrupted rocksnail (Leptoxis foremani) is a smalltomedium sized freshwater snail that historically occurred in the Coosa River drainage of Alabama and Georgia. The shell grows to approximately 22 mm (1 in) in length and may be plicate (folds in the surface) with obscure striations (fine longitudinal ridges), subglobose (not quite spherical), thick, dark, brown to olive in color, and occasionally spotted. The spire (apex) of the shell is very low, and the aperture (opening) is large and subrotund (not quite round).

The interrupted rocksnail, a member of the aquatic snail family Pleuroceridae, was described from the Coosa River, Alabama, by Lea in 1843. Goodrich (1922, p. 13) placed the species in the ``Anculosa (=Leptoxis) picta (Conrad 1834) group,'' which also included the Georgia rocksnail (Leptoxis downei (Lea 1868)). L. foremani was considered to inhabit the Lower Coosa River, with L. downei inhabiting the Upper Coosa drainage (Goodrich 1922, pp. 1819, 2123). When a rocksnail population was rediscovered surviving in the Oostanaula River, Georgia, in 1997, it was initially identified as L. downei (Williams and Hughes 1998, p. 9; Johnson and Evans 2000, pp. 4546); however, Burch (1989, p. 155) had previously placed L. downei within L. foremani as an ecological variation. Therefore, L. downei is currently considered an upstream phenotype of the interrupted rocksnail, and L. foremani is recognized as the valid name for the interrupted rocksnail (Turgeon et al. 1998, p. 67; Johnson 2004, p. 116).

Rocksnails live in shoals, riffles, and reefs (bedrock outcrops) of small to large rivers. Their habitats are generally subject to moderate currents during low flows and strong currents during high flows. These snails live attached to bedrocks, boulders, cobbles, and gravel and tend to move little, except in response to changes in water level. They lay their adhesive eggs within the same habitat (Johnson 2004, p. 116). Interrupted rocksnails are currently found in shoal habitats with sand boulder substrate, at water depths less than 50 centimeters (cm) (20 in), and in water currents less than 40 cm/second (sec) (16 in/sec) (Johnson 2004, p. 116). We know little of the life history of pleurocerid snails; however, they generally feed by ingesting periphyton (algae attached to hard surfaces) and biofilm detritus scraped off of the substrate by the snail's radula (a horny band with minute teeth used to pull food into the mouth) (Morales and Ward 2000, p. 1). Interrupted rocksnails have been observed grazing on siltfree gravel, cobble, and boulders (Johnson 2004, p. 116). They have survived as long as 5 years in captivity (Johnson in litt. 2006b).

The interrupted rocksnail was historically found in colonies on reefs and shoals of the Coosa River and several of its tributaries in Alabama and Georgia. The range of the rocksnail formerly encompassed more than 800 km (500 mi) of river and stream channels, including the Coosa River (Coosa, Calhoun, Cherokee, Elmore, Etowah, Shelby, St. Clair, and Talladega
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Counties), Lower Big Canoe Creek (St. Clair County), and Terrapin Creek (Cherokee County) in Alabama; and the Coosa and Lower Etowah Rivers (Floyd County), the Oostanaula River (Floyd and Gordon Counties), the Coosawattee River (Gordon County), and the Conasauga River (Gordon, Whitfield, and Murray Counties) in Georgia (Goodrich 1922, pp. 19, 21; Johnson 2004, p. 116; FLMNH 2006).

Snail surveys conducted within the historical range of the interrupted rocksnail (Bogan and Pierson 1993a, pp. 127; Williams and Hughes 1998, pp. 121) resulted in the collection of only a single live specimen from the Oostanaula River, Floyd County, Georgia, during 1997 (Williams and Hughes 1998, p. 9). Intensive surveys of the Oostanaula, Coosa, Coosawattee, Etowah, and Conasauga Rivers since 1999 have located the species in about 12 km (7.5 mi) of the Oostanaula River upstream of the GordonFloyd County line (Johnson and Evans 2000, pp. 4546; Johnson and Evans 2001, pp. 2, 25). A captive colony was maintained at the Tennessee Aquarium Research Institute (TNARI) from 2000 through 2005 for study and propagation. In coordination with TNARI and the Service, the Alabama Department of Conservation and Natural Resources (ADCNR) developed a plan and strategy to reintroduce interrupted rocksnails from the TNARI colony into the Coosa River above Wetumpka, Elmore County, Alabama (ADCNR 2003, pp. 14). In 2003, 2004, and 2005, approximately 3,200, 1,200, and 3,000 juvenile snails, respectively, from the TNARI culture were released into the Lower Coosa River (ADCNR 2004, p. 33; P. Johnson in litt. 2005a). In 2005, ADCNR established the Alabama Aquatic Biodiversity Center (AABC) at the Marion State Fish Hatchery for the culture of imperiled mollusk species, and the interrupted rocksnail TNARI colony was transferred to that facility.

Following its rediscovery, the interrupted rocksnail population size on shoals in the Oostanaula River declined from a high of 10 to 45 snails per square meter (m\2\) (1.2 square yards (yd\2\) in 1999 (Johnson and Evans 2001, p. 22) to only 20 snails found during 6 searchhours in 2004 (P. Johnson in litt. 2003, 2004). The cause of decline was suspected to be some form of water contamination (P. Johnson in litt. 2003, 2004; P. Hartfield in litt. 2006). A July 2006 search for adults to use as hatchery stock failed to locate any rocksnails in more than 2 searchhours (P. Hartfield in litt. 2006). However, a subsequent search in August 2006 under lower flow conditions resulted in the location of 89 snails in 4 searchhours at one shoal, and 2 rocksnails in 4 searchhours at another shoal (P. Johnson in litt. 2007a).

Since their reintroduction into the Lower Coosa River of Alabama, a few of the 2003 hatcherycultured interrupted rocksnails were observed in the vicinity of the release site in 2004 (Johnson in litt. 2005c). An alternative site was selected for release in August 2005, and 18 snails were located 3 months following release (M. Pierson in litt. 2005). During a 40minute search of this release area in 2006, two interrupted rocksnails were found (P. Johnson in litt. 2007b). Observations of only small numbers of reintroduced snails may be due to habitat size and dispersal, low fecundity of the species, predation, reproductive failure due to dispersal, or habitat disturbance (Johnson in litt. 2005b).

Rough Hornsnail

The rough hornsnail's (Pleurocera foremani) shell is elongated, pyramidal, and thick. Growing to about 33 mm (1.3 in) in length, the shell has as many as nine yellowishbrown whorls. The aperture is elongated, angular, channeled at the base, and usually white inside. The presence of prominent nodules or tubercles on the lower whorls above the aperture is the most distinctive feature that separates it from other hornsnails (Tryon 1873, p. 53). These tubercles, along with the size and shape of the shell, distinguish the species from all other pleurocerid snails (Elimia spp., Leptoxis spp., Pleurocera spp.) in the Mobile River Basin.

The rough hornsnail is a member of the aquatic snail family of Pleuroceridae. The species was described in 1843 by Lea as Melania foremanii (=foremani) (Tryon 1873, p. 52). It was later placed in the genus Pleurocera by Tryon (1873, p. 52), who noted that P. foremani closely resembled species of that genus. Goodrich (1935, p. 3) reported a variation of a species of Pleurocera in the Cahaba River that resembled foremani, but later identified that variant as a ``mutation'' or form of brook hornsnail (P. vestitum) (Goodrich 1941, p. 12). This variant, however, is no longer extant in the Cahaba River (Bogan and Pierson 1993b, p. 12; Sides 2005, pp. 2122, 28). Goodrich (1944, p. 43) considered that the Coosa River P. foremani might also be eventually found to be simply a variant of smooth hornsnail (P. prasinatum), another more widely distributed species in the Coosa River.

In a recent dissertation on the systematics of the Mobile River Basin Pleurocera, the rough hornsnail was found to be both morphologically and genetically distinct from other species in the genus (Sides 2005, pp. 26, 127). This analysis also found that the rough hornsnail was genetically more closely allied to a cooccurring species in the genus Elimia, and concluded that it should be recognized as Elimia foremani (Sides 2005, pp. 2627). Although the Sides (2005, pp. 2627) study provides some evidence that this species should be placed in the genus Elimia, this taxonomic change has not been formally peerreviewed and published. Therefore, for the purposes of this action, we will continue to use currently recognized nomenclature for the rough hornsnail (Pleurocera foremani).

Rough hornsnails are primarily found on gravel, cobble, and bedrock in moderate currents. They have been collected at depths of 1 m (3.3 ft) to 3 m (9.8 ft) (Hartfield 2004, p. 132). The species appears to tolerate lowtomoderate levels of silt deposition (Sides 2005, p. 127). Little is known regarding the life history characteristics of this species. Snails in the genus Pleurocera generally lay their eggs in a spiral arrangement on smooth surfaces (Sides 2005, pp. 2627), whereas Elimia snails generally lay eggs in short strings (P. Johnson 2006). Attempts to induce rough hornsnails to lay eggs in captivity have been unsuccessful (Sides 2005, p. 27).

The rough hornsnail is endemic to the Coosa River system in Alabama. Goodrich (1944, p. 43) described the historical range as the Coosa River downstream of the Etowah River and at the mouths of a few tributaries. The Etowah River enters the Coosa River in Floyd County, Georgia; however, there are no known museum or sitespecific records of the rough hornsnail that validate its range into the State of Georgia (P. Johnson in litt. 2006a). Historical museum records of the rough hornsnail in the Coosa River (FLMNH 2006, and elsewhere) indicate that they occurred from Etowah, St. Clair, Shelby, Talladega, and Elmore Counties, Alabama, a historical range of approximately 322 river km (200 river mi). There are also historical museum records of this species from nine Coosa River tributaries in Alabama, including Big Wills Creek in Etowah County; Kelly, Big Canoe, and Beaver Creeks in St. Clair County; Ohatchee Creek, Calhoun County; Choccolocco and Peckerwood Creeks in Talladega County; Yellowleaf Creek, Shelby County; and Yellow Leaf Creek in Chilton County (FLMNH 2006).

The rough hornsnail is currently known to occur at two locations: Lower
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Yellowleaf Creek in Shelby County, Alabama; and the Lower Coosa River below Wetumpka Shoals in Elmore County, Alabama (Sides 2005, p. 40). There are also museum records of the species from Wetumka Shoals in the early 1990s (FLMNH 2006); however, the species has not been collected from the shoal reach in recent surveys (Johnson 2002, pp. 59). Yellowleaf Creek is a moderately sized stream where rough hornsnails have been collected from about a 50m (55yd) length of the stream. At this location, rough hornsnails occur at densities of 8 to 32 m\2\ (1.2 yd\2\) (Pierson in litt. 2006). The Lower Coosa River is a large river channel where rough hornsnails have been found in an area of about 100 m\2\ (120 yd\2\) (P. Hartfield 2001). No quantitative estimates have been made at this site. Searches of unimpounded reaches of the Coosa River and the lower portions of tributaries to the Coosa have failed to locate the species elsewhere (Bogan and Pierson 1993a, pp. 127; Garner, pers. com. 2005; Hartfield in litt. 2006). The two known surviving populations are separated by three impoundments and about 113 km (70 mi) of impounded channel habitat.

Previous Federal Action

The interrupted rocksnail and rough hornsnail were first identified as candidates for protection under the Act in the November 21, 1991, Federal Register (56 FR 58804). They were assigned a category 2 status designation, which was given to those species for which there was some evidence of vulnerability, but for which additional biological information was needed to support a proposed rule to list as endangered or threatened. In the November 15, 1994, notice of candidate review (59 FR 58982), the rough hornsnail was again assigned a category 2 status, while the status category for the interrupted rocksnail (Leptoxis foremani) was changed to 3A (taxa for which the Service has persuasive evidence of extinction).

Assigning categories to candidate species was discontinued in 1996 (Notice of Candidate Review; February 28, 1996; 61 FR 7596), and only species for which the Service has sufficient information on biological vulnerability and threats to support issuance of a proposed rule are now regarded as candidate species. Candidate species were also assigned listing priority numbers based on immediacy and the magnitude of threat, as well as their taxonomic status (48 FR 43098; Sept. 21, 1983). Due to a need for taxonomic clarification, the rough hornsnail was dropped as a candidate species in 1996.

In 1997, we received reports of a small population of the interrupted rocksnail surviving in the Ostanaula River, Georgia, along with reports of Georgia pigtoe collections in the Conasauga River of Georgia and Tennessee, and their status as candidates was reevaluated. In the 1999 (64 FR 57533), 2001 (66 FR 54808), 2002 (67 FR 40657), and 2004 (69 FR 24876) Federal Register notices of candidate review, both the Georgia pigtoe and interrupted rocksnail (as Georgia rocksnail, Leptoxis downei) were identified as listing priority 5 candidate species. In the May 11, 2005, Federal Register notice of candidate review (70 FR 24870) the nomenclature was corrected for the interrupted rocksnail, and the listing priority for both species was changed from 5 to 2, based on the continued rarity of the Georgia pigtoe and a decline in abundance of the interrupted rocksnail. The rough hornsnail was recognized as a listing priority 2 candidate in the September 12, 2006, Federal Register notice of candidate review (71 FR 53756), following clarification of its taxonomy, along with the interrupted rocksnail and Georgia pigtoe.

Summary of Factors Affecting the Species

Section 4 of the Act (16 U.S.C. 1533), and implementing regulations at 50 CFR part 424, set forth procedures for adding species to the Federal Lists of Endangered and Threatened Wildlife and Plants. Under section 4(a) of the Act, we may list a species on the basis of any of five factors, as follows: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B)
overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; or (E) other natural or manmade factors affecting its continued existence. In making this finding, information regarding the status and trends of the Georgia pigtoe, interrupted rocksnail, and rough hornsnail are considered in relation to the five factors provided in section 4(a)(1) of the Act.

Under section 3 of the Act, a species is ``endangered'' 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'' refers to the range in which the species currently exists. Range is discussed further below in the Conclusion section of this proposed rule.

Foreseeable future is determined by the Service on a casebycase basis, taking into consideration a variety of speciesspecific factors such as lifespan, genetics, breeding behavior, demography, threat projection timeframes, and environmental variability.

The average lifespan of the interrupted rocksnail in the wild is unknown; however, interrupted rocksnails have survived in captivity for as long as 5 years (Johnson in litt. 2006b). Heavyshelled mussels are known to have long life spans, with many species living from 30 to 70 years (Williams et al. 2008, p. 68). For the purposes of this analysis, we estimate a life span of 30 years for the Georgia pigtoe.

Some percentage of rocksnails cultured in captivity have been observed ovipositing in their first year, but all are believed to become sexually mature in their second year. Less is known about the rough hornsnail; however, some pleurocerid snails in the genus Elimia may live up to 5 years (Dillon 1988, p. 113). It is also believed that most pleurocerid snails may begin reproducing within 1 year posthatch, depending upon habitat and productivity (Johnson 2008).

The age of sexual maturity for the Georgia pigtoe is unknown and varies widely among the genera of freshwater mussels. In general, thin shelled species reach sexual maturity earlier and have shorter lifespans than heaviershelled species. In the Mobile River Basin, age at sexual maturity for mussels has been shown to vary from 1 to 2 years for the thinshelled southern pocketbook (Lampsilis ornata), and 3 to 9 years for the heavyshelled Alabama orb (Quadrula asperata) (Haag and Staton 2003, pp. 21222123). The Georgia pigtoe is similar in shell size and thickness to the Alabama orb, so we are estimating sexual maturity for the Georgia pigtoe at age 5 years, and a generational time span of 5 years. Heavyshelled mussels are also known to have long life spans, with many species living from 30 to 70 years (Williams et al. 2008, p. 68).

Threat projection timeframes for the Georgia pigtoe, interrupted rocksnail, and rough hornsnail include specific activities that can arise at any time (such as permitted discharges, construction activities, channel modifications, or random accidents and spills of toxic substances) and periodic weather events (such as droughts and floods).

The following analysis examines all five factors currently affecting or that are likely to affect Georgia pigtoe,
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interrupted rocksnail, and rough hornsnail snail. The five factors listed under section 4(a)(1) of the Act and their application to the Georgia pigtoe mussel (Pleurobema hanleyianum (Lea 1852)), interrupted rocksnail (Leptoxis foremani (Lea 1843)), and rough hornsnail (Pleurocera foremani (Lea 1843)) are as follows:
A. The present or threatened destruction, modification, or curtailment of its habitat or range.

All three species have experienced significant curtailment of their occupied habitats (see ``Background'' above). The Georgia pigtoe has been eliminated from about 90 percent of its historical range of 480 river km (298 river mi). It now inhabits only 43 river km (27 river mi). Interrupted rocksnail has been eliminated from 99 percent of a historical range of 800 river km (497 river mi), and is now known from 12 river km (7 river mi). The rough hornsnail has disappeared from more than 99 percent of a historical range of 321 river km (199 river mi) and now occurs in less than 1 river km (0.6 river mi). The primary cause of range curtailment for all three species has been modification and destruction of river and stream habitats, primarily by the construction of large hydropower dams on the Coosa River. This was compounded by fragmentation and isolation of the remaining freeflowing portions of the Coosa River and its tributaries, as well as their increased vulnerability to local historical events of water quality and habitat degradation.

Dams and Impoundments

Dams eliminate or reduce river flow within impounded areas, trap silts and cause sediment deposition, alter water temperature and dissolved oxygen levels, change downstream water flow and quality, affect normal flood patterns, and block upstream and downstream movement of species (Watters 1999, pp. 261264; McAllister et al. 2000, p. iii; Marcinek et al. 2005, pp. 2021). Within impounded waters, decline of freshwater mollusks has been attributed to sedimentation, decreased dissolved oxygen, and alteration in resident fish populations (Neves et al. 1997, pp. 6364; Watters 1999, pp. 261264; Marcinek et al. 2005, pp. 910). Below dams, mollusk declines are associated with changes and fluctuation in flow regime, scouring and erosion, reduced dissolved oxygen levels and water temperatures, and changes in resident fish assemblages (Williams et al. 1992b, p. 7; Neves et al. 1997, pp. 6364; Watters 1999, pp. 261264; Marcinek et al. 2005, pp. 2021). The decline and extinction of freshwater snails and mussels in the Mobile River Basin has been directly attributed to construction of numerous large impoundments in the major river systems (Williams et al. 1992b, pp. 18; Bogan et al. 1995, pp. 250251; Lydeard and Mayden 1995, pp. 803804; Neves et al. 1997, pp. 62, 64; Marcinek et al. 2005, p. 9).

The Georgia pigtoe, interrupted rocksnail, and rough hornsnail are all endemic to the Coosa River system. The Coosa River was impounded by six major dams constructed between 1928 and 1966. Today, more than 60 percent of the Coosa River and its 19 largest tributaries are inundated or affected by flow regulation (Marcinek et al. 2005, pp. 1216).

Dam construction on the Coosa River had a secondary effect of fragmenting the ranges of aquatic mollusk species, leaving relict habitats and populations isolated by the structures as well as by extensive areas of uninhabitable, impounded waters. These isolated populations were left more vulnerable to, and affected by, natural events (such as droughts), runoff from common landuse practices (such as agriculture, mining, urbanization), discharges (such as municipal and industrial wastes), and accidents (such as chemical spills) that reduced population levels or eliminated habitat (Neves et al. 1997, pp. 6471; U.S. Fish and Wildlife Service 2000, pp. 1415). As a result, many relict populations became locally extirpated, and many mollusk species were driven to extinction (Bogan et al. 1995, pp. 250251; Lydeard and Mayden 1995, pp. 803804; Neves et al. 1997, pp. 54, 62; U.S. Fish and Wildlife Service 2000, pp. 69). If conditions subsequently improved, the surviving mollusk species were unable to naturally recolonize suitable areas, due to impediments created by the dams and impounded waters.

The only known natural population of the interrupted rocksnail occurs in the freeflowing Oostanaula River (Williams and Hughes 1998, p. 9; Johnson and Evans 2001, p. 25). The Oostanaula River is formed by the confluence of the Conasauga and Coosawatee Rivers. The Upper Coosawatee is impounded by Carters Dam, a hydropower dam which discharges into Carters Reregulation Dam and from there into the Coosawatee River. Hydropower discharges from Carters Dam are believed to be implicated in the disappearance of the interrupted rocksnail from the Coosawattee River (Johnson and Evans 2001, p. 26). The effects of power generation discharges from Carters Dam, along with cold water temperatures are evident downstream (Williams and Hughes 1998, p. 11), even to the shoals on the Oostanaula River where the interrupted rocksnail is found (Johnson and Evans 2001, p. 26; Marcinek et al. 2005, p. 15). A Federal Energy Regulatory Commission (FERC) license was issued to construct a hydroelectric facility on the Carters Re regulation Dam (FERC 2001, pp. 12). A notice of probable termination of license has been issued due to failure to commence construction in a timely manner (FERC 2005a, pp. 12). An appeal to the termination order was made (FERC 2005b, p. 1) but denied (FERC 2006a, pp. 13). However, the applicant has since applied for a preliminary permit to proceed with the hydroelectric facility (FERC 2006b, pp. 13).

Rough hornsnails currently survive in Lower Yellowleaf Creek, at the transitional area between the flowing stream and the embayment created by Lay Dam, and in a small area of the Coosa River below the shoals along the Fall Line near Wetumpka, Alabama. Known from the main channel of the Coosa River and the mouths of some of the larger tributaries, all historical habitats, including those two where the rough hornsnail currently survives, are affected to some degree by impounded waters and hydropower releases.

The Georgia pigtoe historically occurred in the Coosa River and many of its major tributaries. As noted above, the Coosa is impounded throughout most of its length by major hydropower dams. In addition, all historically occupied tributaries are isolated from each other by one or more of these dams and extensive reaches of impounded waters. The species is currently known to survive only in the Upper Conasauga River, far above the influence of the Coosa River impoundments. Water and Habitat Quality

The disappearance of shoal populations of rough hornsnail, interrupted rocksnail, and Georgia pigtoe from unimpounded relict habitats in the Coosa River drainage is likely due to historical pollution problems. Pleurocerid snails and freshwater mussels are highly sensitive to water and habitat quality (Havlik and Marking 1987, pp 115; Neves et al. 1997, pp. 6469). Historical causes of water and habitat degradation in the Coosa River and its tributaries included drainage from gold mining activities, industrial and municipal pollution events, and construction and agricultural runoff (for example, Hurd 1974, pp. 3840; Lydeard and Mayden 1995, pp. 803804; Freeman et al. 2005, pp. 560562).

[[Page 31119]]

Prior to the passage of the Federal Clean Water Act (33 U.S.C. 1251 et seq., 1972) and the adoption of State water quality regulations and criteria, water pollution was a significant factor in the disappearance of mollusks from unimpounded river and stream channels in the Mobile River Basin (Baldwin 1973, p. 23; Hurd 1974, pp. 3840, 144151). Hurd (1974, pp. 147149), for example, noted the extirpation of freshwater mussel communities from the Conasauga River below Dalton, Georgia, apparently as a result of textile and carpet mill waste discharges. He also attributed the disappearance of the mussel fauna from the Etowah River and other tributaries of the Coosa River to organic pollution and siltation. Baldwin (1973, p. 23) documented the loss of mussel diversity in the Cahaba River and identified the primary causes as pollution from coalfields and industrial and urban wastes.

Although Federal and State water quality laws and regulations have generally reduced the impacts of point source discharges, nonpoint source pollution continues to affect and possibly threaten the remaining populations of each of these mollusk species. Nonpoint source pollution has been identified as a concern in the Yellowleaf Creek and Lower Coosa River watersheds (Alabama Clean Water Partnership (ACWP) 2005 Chapter 12). These drainages encompass historical habitat for the interrupted rocksnail and Georgia pigtoe, currently occupied habitat for the rough hornsnail, and a recent reintroduction of the interrupted rocksnail. Both Yellowleaf Creek and the eastern watershed of the Lower Coosa River have been designated as High Priority Watersheds by the ACWP (2005 Chap. 12), due to the high potential of nonpoint source pollution associated with expanding human population growth rates and urbanization. The headwaters of Yellowleaf Creek are about 5 km (3 mi) southeast of the greater metropolitan area surrounding Birmingham, and the watershed is highly dissected by county roads. The Lower Coosa River is about 16 km (10 mi) north of the Montgomery greater metropolitan area and is accessible by a fourlane highway. Both general areas are experiencing growth due to their proximity to major metropolitan areas.

Nonpoint source pollution and habitat deterioration are also problems in the Upper Coosa River Basin, including the Conasauga and Oostanaula rivers (Georgia Department of Natural Resources (GDNR) 1998, pp. 4.274.42). In the reaches of the Conasauga River where the Georgia pigtoe continues to survive, overall molluscan abundance and diversity have experienced a general decline over the past two decades that has been primarily attributed to water or sediment toxicity and channel instability (Johnson and Evans 2000, pp. 171173; Sharpe and Nichols 2005, pp. 8188). Sedimentation has been identified as a potential limiting factor for the interrupted rocksnails in the Oostanaula River (Johnson and Evans 2001, p. 26). Following its rediscovery, the interrupted rocksnail population size in the Oostanaula River has declined from a high of 10 to 45 snails per square meter (10.7 sq ft) in 1999 (Johnson and Evans 2001, p. 22) to only 20 snails found during 6 searchhours in 2004 (P. Johnson in litt. 2003, 2004). The cause of decline is suspected to be some form of water contamination (P. Johnson in litt. 2003, 2004; P. Hartfield in litt. 2006).

Nonpoint source pollution from land surface runoff originates from virtually all land use activities and includes sediments; fertilizer, herbicide, and pesticide residues; animal or human wastes; septic tank leakage and gray water discharge; and oils and greases (GDNR 1998, pp. 4.274.42; ACWP 2005, Chap. 9). Nonpoint source pollution can cause excess sedimentation, nutrification, decreased dissolved oxygen concentration, increased acidity and conductivity, and other changes in water chemistry that can seriously impact aquatic mollusks. Land use types around the Georgia pigtoe, interrupted rocksnail, and rough hornsnail populations include pastures, row crops, timber, and urban and rural communities.

Excessive sediments are believed to impact riverine mollusks requiring clean, stable streams (Ellis 1936, pp. 3940; Brim Box and Mossa 1999, p. 99). Impacts resulting from sediments have been noted for many components of aquatic communities. For example, sediments have been shown to abrade or suffocate periphyton (organisms attached to underwater surfaces, upon which snails may feed); affect respiration, growth, reproductive success, and behavior of aquatic insects and mussels; and affect fish growth, survival, and reproduction (Waters 1995, pp. 173175). Potential sediment sources within a watershed include virtually all activities that disturb the land surface, and all localities currently occupied by these mollusks are affected to varying degrees by sedimentation.

Land surface runoff also contributes nutrients to rivers and streams. Excessive nutrient input (for example, nitrogen and phosphorus from fertilizers, sewage, and animal manure) can result in effects that are detrimental to aquatic species. High levels of nutrients in surface runoff can promote excessive filamentous algal growth. Dense algal growth covers gravel, cobble, or bedrock substrates and interstices (spaces between bottom particles), and can seriously reduce dissolved oxygen in waters during dark hours due to algal respiration (Shepard et al. 1994, pp. 6164), which affects feeding, reproduction, and respiration in adult and juvenile mussels and snails, and limits access to substrate interstices important to juvenile and adult mussels. Algal mats also provide cover for invertebrate predators of juvenile mollusks (such as flatworms, hydra, and chironomids) and increase their vulnerability to such predators. Filamentous algae may also displace certain species of fish, or otherwise affect fishmussel interactions essential to recruitment (for example, Hartfield and Hartfield 1996, p. 373). In hatcheries, filamentous algal growth reduces juvenile mussel survival by reducing flow, increasing sedimentation, and causing competition with and reduction of the unicellular algal community on which the mussels feed (R. Neves 2002). Nutrient and sediment pollution may have synergistic effects (when the toxic effect of two or more pollutants operating together is greater than the sum of the effects of the pollutants operating individually) on freshwater mollusks, as has been suggested for aquatic insects (Waters 1995, p. 67).

Land surface runoff contributes the majority of humaninduced sediments and nutrients to water bodies throughout the United States. The human population is expanding within the areas currently occupied by the Georgia pigtoe, interrupted rocksnail, and rough hornsnail, increasing the sediment and nutrient input to their riverine habitats, and leaving these mollusks vulnerable to progressive water and habitat degradation from land surface runoff.

Accidental spills that may affect water or habitat quality also threaten surviving populations of each species. For example, on September 12, 2006, a train derailment spilled four tank cars of soybeans into a tributary of Yellowleaf Creek (Birmingham News in litt. 2006). A large rain event flushed the decomposing soybeans into Yellowleaf Creek, resulting in a serious decline in dissolved oxygen in the stream, killing fishes, mussels (including two endangered species, southern pigtoe and triangular kidneyshell), and snails (including the endangered cylindrical
[[Page 31120]]
lioplax) (Johnson 2006). Fortunately, the location of the largest surviving population of rough hornsnail is in the lowest reaches of Yellowleaf Creek, remote from the spill, and no mortality was observed in this population as a result of the spill (Johnson 2006).

In summary, the historical loss of habitat and range is currently, and projected to continue to be, a significant threat to the rough hornsnail, interrupted rocksnail, and Georgia pigtoe. Curtailment of habitat and range also amplifies threats from nonpoint source water and habitat quality degradation, accidental spills, or violation of permitted discharges. Due to the extremely limited extent of habitat currently occupied by each species, and the severity and magnitude of this threat, we have determined that the present or threatened destruction, modification, or curtailment of habitat and range represents an ongoing and significant threat to the rough hornsnail, interrupted rocksnail, and Georgia pigtoe.
B. Overutilization for commercial, recreational, scientific, or educational purposes.

The Georgia pigtoe, interrupted rocksnail, and rough hornsnail are not commercially utilized. Each species has been taken for scientific and private collections in the past, yet collecting is not considered a factor in the decline of these species. While collection is not considered a current threat, the desirability of these species in scientific and commercial collections may increase as their existence and rarity becomes known, and their localized distributions and small population sizes leaves them vulnerable to overzealous recreational or scientific collecting.

C. Disease or predation.

Diseases of freshwater mollusks are poorly known and are not currently considered to be a threat to the Georgia pigtoe, interrupted rocksnail, and rough hornsnail, or a factor in their decline. Aquatic snails and mussels are consumed by various vertebrate predators, including fishes, mammals, and possibly birds. Although predation by naturally occurring predators is a normal aspect of the population dynamics of a species and is not known to be a threat to any of these species, changes in water flows, depths, temperatures, and other environmental factors within some portions of their ranges may have led to increased numbers of native molluskeating fish, such as freshwater drum (Johnson in litt. 2005b). In addition, the potential now exists for the black carp (Mylopharyngodon piceus), a molluskeating Asian fish recently introduced into the waters of the United States (U.S. Fish and Wildlife Service 2002), to eventually enter and disperse through the Mobile River Basin via the TennesseeTombigbee Waterway, or by their accidental release from catfish farms or other aquaculture facilities.

In summary, disease in freshwater mollusks is poorly known and not currently considered a threat. Although there is no direct evidence at this time that predation is detrimentally affecting the Georgia pigtoe, interrupted rocksnail, or rough hornsnail, their small populations and limited ranges leaves them vulnerable to threats of predation from natural or introduced predators. Therefore, we have concluded that predation currently represents a threat of low magnitude, but it could potentially become a significant future threat to the Georgia pigtoe, interrupted rocksnail, or rough hornsnail due to their small population sizes.

D. The inadequacy of existing regulatory mechanisms.

The Alabama Department of Conservation and Natural Resources currently recognizes the rough hornsnail as a ``Priority 1'' species (Highest Conservation Concern) (Mirarchi et al. 2004, p. 117; ADCNR 2005, p. 302). The interrupted rocksnail is considered ``Extirpated (in Alabama) Conservation Action Underway'' (Mirarchi et al. 2004, p. 114), and the Georgia pigtoe is listed as ``extinct'' (Mirarchi et al. 2004, p. 13). While these classifications identify the status of imperiled species in the State of Alabama, they convey no legal protection. Interrupted rocksnail and Georgia pigtoe currently lack any official status recognition by the State of Georgia, but they have been nominated for inclusion on the State Protected Species List. The Georgia pigtoe is identified as a species of the Greatest Conservation Need by the State of Tennessee. NatureServe (2006) identifies the Georgia pigtoe, interrupted rocksnail, and rough hornsnail as G1 critically imperiled species; however, no State or Federal protection is conveyed by these classifications. Without State or Federal protection, these three species are not currently given any specific special consideration under environmental laws when project impacts are reviewed, other than those provided for water quality.

The mollusk fauna (including the Georgia pigtoe) of the Conasauga River and the interrupted rocksnail in the Oostanaula River have experienced significant declines in recent years, apparently due to water quality or sediment toxicity (Evans 2001, p. 3; Johnson in litt. 2004; Sharpe and Nichols 2005, pp. 14; Konwick et al. 2008, pp. 2016 2017). There is no specific scientific information on the sensitivity of the Georgia pigtoe, interrupted rocksnail, and rough hornsnail or their host fish species to common industrial and municipal pollutants, and little information on other freshwater mollusks. Current State and Federal regulations regarding pollutants are assumed to be protective of freshwater mollusks; however, these species may be more susceptible to some pollutants than test organisms commonly used in bioassays. For example, several recent studies have suggested that U.S. Environmental Protection Agency's (EPA) criteria for ammonia may not be protective of freshwater mussels (Augspurger et al. 2003, p. 2571; Augspurger et al. 2007, p. 2026; Newton et al. 2003, pp. 25592560; Newton and Bartsch 2007, p 2057; Ward et al. 2007, p. 2075).

In a review of the effects of eutrophication on mussels, Patzner and Muller (2001, p. 329) noted that stenoecious (narrowly tolerant) species disappear as waters become more eutrophic. They also refer to studies that associate increased levels of nitrate with the decline and absence of juvenile mussels (Patzner and Muller 2001, pp. 330333). Other studies have also suggested that early life stages of mussels are more sensitive to metals and such inorganic chemicals as chlorine and ammonia than are common bioassay test organisms (Keller and Zam 1991, pp. 543545; Goudreau et al. 1993, p. 221; Naimo 1995, pp. 354355). Therefore, it appears that inadequate research and data prevent existing regulations, such as the Clean Water Act (administered by the EPA and the U.S. Army Corps of Engineers), from being fully utilized or effective in the management and protection of these species.

Rough hornsnails currently survive at localized sites in Yellowleaf Creek and in the Lower Coosa River below Wetumpka Shoals in Alabama. In addition, the interrupted rocksnail was recently reintroduced into Wetumpka Shoals. The Alabama Department of Environmental Management (ADEM) has designated the water use classification for some portions of Yellowleaf Creek as ``Swimming'' (S) and others as ``Fish and Wildlife'' (F&W). The F&W designation establishes minimum water quality standards that are believed to protect
[[Page 31121]]
existing species and water uses (for example, fishing, recreation, irrigation) within the designated area, while the S classification establishes higher water quality standards that are protective of human contact with the water. The Lower Coosa River below Wetumpka is currently designated as F&W by ADEM, and adjacent tributaries are classified as S. Both water bodies are currently believed to support their designated uses. However, Yellowleaf Creek and the eastern watershed of the Lower Coosa have been designated as High Priority Watersheds by the ACWP (2005, Chap. 12) due to a lack of monitoring data and the high potential of nonpoint source pollution in these drainages associated with expanding human population growth rates and urbanization.

The reach of the Conasauga River at and below the TennesseeGeorgia State Line supports the only known surviving population of the Georgia pigtoe. This river reach is identified on Georgia's 303(d) list as partially supporting its designated use of FishingDrinking Water (GDNR 2006, p. 35). The Georgia 303(d) list identifies high levels of fecal coliform bacteria and Fish Consumption Guidance (FCG) due to polychlorinated biphenyls (PCBs) as the reasons for this river reach's inclusion on the list, and nonpoint pollution is identified as the source of pollutants (GDNR 2006, p. 35). Recent studies have also implicated sediment and water toxicity in the decline of mollusks in the Conasauga River (Sharpe and Nichols 2005, pp. 8188; Konwick et al. 2008, pp. 20162017).

States maintain wateruse classifications through issuance of National Pollutant Discharge Elimination System (NPDES) permits to industries, municipalities, and others that set maximum limits on certain pollutants or pollutant parameters. For water bodies on the 303(d) list, States are required under the Clean Water Act to establish a total maximum daily load (TMDL) for the pollutants of concern that will bring water quality into the applicable standard. The Georgia Department of Natural Resources has identified TMDLs for the Oostanaula River to address existing problems of PCBs and fecal coliform loads from nonpoint source and urban runoff sources.

In summary, recent declines in mollusk communities within the ranges of each of these species has been attributed to poor water or sediment quality. Although regulatory mechanisms are in place to protect aquatic species, a lack of specific information on the sensitivity of the Georgia pigtoe, interrupted rocksnail, and rough hornsnail and their host fish to common industrial and municipal pollutants limits their application. Water and sediment quality is believed to currently affect (and is expected to continue to affect) the Georgia pigtoe and interrupted rocksnail and has been identified as a concern for the rough hornsnail in Yellowleaf Creek. Therefore, we have determined that the threat of inadequate existing regulatory mechanisms is an imminent threat of high magnitude to the Georgia pigtoe, interrupted rocksnail, and rough hornsnail.
E. Other natural or manmade factors affecting its continued existence.

As noted under Factor A, above, the Georgia pigtoe, interrupted rocksnail, and rough hornsnail have been eliminated from 90 percent or more of their historical ranges. Surviving populations of each species are small, extremely localized, isolated, and vulnerable to habitat modification, toxic spills, and progressive degradation from land surface runoff (nonpoint source runoff) (see Factor A: Dams and Impoundments, Water and Habitat Quality; and Factor D: The inadequacy of existing regulatory mechanisms). These conditions also leave each species vulnerable to catastrophic changes to their habitats that may result from natural events such as flood scour and drought.

There is a growing concern that climate change may lead to increased frequency of severe storms and droughts (for example, Golladay et al. 2004, p. 504; McLaughlin et al. 2002, p. 6074; Cook et al. 2004, p. 1015). During 20072008, a severe drought affected the Coosa River watershed in Alabama and Georgia. Streamflow for the Conasauga River at Tilton, Georgia, during September 2007, was the lowest recorded for any month in 69 years (U.S. Geological Survey 2007). Although the effects of the drought on the Georgia pigtoe, interrupted rocksnail, and rough hornsnail have not been quantified, mollusk declines as a direct result of drought have been documented (for example, Golladay et al. 2004, p. 494; Haag and Warren 2008, p. 1165). Reduction in local water supplies due to drought is also compounded by increased human demand and competition for surface and ground water resources for power production, irrigation, and consumption (Golladay et al. 2004, p. 504).

Freshwater mussels and snails are capable of moving only short distances. As noted previously (see discussion under Factor A: Dams and Impoundments), there are numerous obstacles in the Coosa River drainage to long distance movement of snails, mussels, or the fish hosts of mussels, between relict patches of historically occupied and potentially suitable riverine habitats. Therefore, even if habitat conditions improve for the survival of the Georgia pigtoe, interrupted rocksnail, and rough hornsnail in historically occupied stream and river habitats, they will be unable to recolonize those areas without human assistance. Low numbers of individuals within these isolated populations also increases the risks and consequences of inbreeding and reduced genetic diversity (Lynch 1996, pp. 493494).

The Georgia pigtoe may be adversely affected by the loss or reduction in numbers of the fish host(s) essential to its parasitic glochidial stages. The specific fish host(s) for the glochidia of the Georgia pigtoe is unknown; therefore, specific impacts on this aspect of the mussels' life cycle cannot be evaluated. However, other species of mussels in the genus Pleurobema are known to parasitize various species of chubs, minnows, stonerollers, and other stream fish species.

In summary, a variety of natural or manmade factors, such as droughts, storms, and toxic spills, threaten surviving populations of the Georgia pigtoe, interrupted rocksnail, and rough hornsnail due to the highly restricted and fragmented nature of their habitats and their small population sizes. Other factors, such as inbreeding, reduced genetic diversity, and loss or reduction of fish hosts for the Georgia pigtoe, may threaten each of the three species; however, the severity and magnitude of these threats are not currently known. Therefore, we have determined that other natural and manmade factors, such as accidental spills, floods, and droughts, currently pose an imminent and high degree of threat to the Georgia pigtoe, interrupted rocksnail, and rough hornsnail, and the levels of these threats are projected to continue or increase in the future.

Proposed Determination

We have carefully assessed the best scientific and commercial information available regarding the past, present, and future threats to the Georgia pigtoe, interrupted rocksnail, and rough hornsnail. Section 3(6) of the Act defines an endangered species as ``any species which is in danger of extinction throughout all or a significant portion of its range.'' Based on the severity and magnitude of the threats currently affecting each of these species, we
[[Page 31122]]

propose to list them as endangered species under the Act.

The most significant historical factor affecting the current status of the interrupted rocksnail, rough hornsnail, and Georgia pigtoe was the extreme curtailment of their habitat and range, as discussed in Factor A (above). Curtailment of habitat and range, along with small population sizes, amplifies existing or impending threats from nonpoint source water and habitat quality degradation, accidental spills, violation of permitted discharges, inadequate knowledge to implement existing regulatory measures, floods, or droughts (described under Factors A, D, and E). These threats are imminent and high in magnitude (applicable to the entire range) for each species. As described in Factor C and E above, small populations are also at increased threat due to predation from natural or introduced predators, genetic isolation, and inbreeding depression; however, these threats are not currently known to be imminent.

Only single, localized populations are known to exist of the interrupted rocksnail and Georgia pigtoe, and only two extremely localized populations of the rough hornsnail are known. Each species is faced with a tenuous future even with only the random variation of natural environmental factors. However, the additional threats of water and habitat quality degradation or destruction further threaten each species and this trend is expected to continue or increase.

We believe that, when combining the effects of historical, current, and projected habitat loss and degradation, historical and ongoing drought, and the exacerbating effects of small population sizes and isolation, the interrupted rocksnail, rough hornsnail, and Georgia pigtoe are in danger of extinction throughout all of their ranges, as defined in the ``Summary of Factors Affecting the Species'' above. We believe these threats, particularly the threats resulting from habitat loss and fragmentation, small population sizes, and random natural or human induced events, are current and are projected to continue. We have determined that these threats are operating on each species and their respective habitats with a high degree of imminence, magnitude, and severity (rangewide), as discussed above.

Based on the best available scientific and commercial information, we propose to list the Georgia pigtoe, interrupted rocksnail, and rough hornsnail as endangered species under the Act. Without the protection of the Act, these species are in danger of extinction throughout all of their ranges. This could occur within a few years, given recurring drought conditions, accidents, or other existing threats. Furthermore, because of their curtailed ranges, and immediate and ongoing significant threats to each species throughout their entire respective ranges, as described above in the fivefactor analysis, we find that it is unnecessary to analyze whether there are any significant portions of ranges for each species that may warrant a different determination of status.

Critical Habitat

Critical habitat is defined in section 3 of the Act as: (1) The specific areas within the geographical area occupied by a species, at the time it is listed in accordance with the Act, on which are found those physical or biological features
(a) essential to the conservation of the species and
(b) which may require special management considerations or protection; and
(2) specific areas outside the geographical area occupied by a species at the time it is listed, upon a determination that such areas are essential for the conservation of the species.

Conservation, as defined under section 3 of the Act, means to use and the use of all methods and procedures that are necessary to bring any endangered species or threatened species to the point at which measures provided under the Act are no longer necessary.

Critical habitat receives protection under section 7 of the Act through the prohibition against Federal agencies carrying out, funding, or authorizing the destruction or adverse modification of critical habitat. Section 7(a)(2) of the Act requires consultation on Federal actions that may affect critical habitat. The designation of critical habitat does not affect land ownership or establish a refuge, wilderness, reserve, preserve, or other conservation area. Such designation does not allow the government or public to access private lands. Such designation does not require implementation of restoration, recovery, or enhancement measures by private landowners. Where a landowner requests Federal agency funding or authorization for an action that may affect a listed species or critical habitat, the consultation requirements of Section 7(a)(2) may apply. However, even in the event of a destruction or adverse modification finding, the Federal action agency's and the applicant's obligation is not to restore or recover the species, but to implement reasonable and prudent alternatives to avoid destruction or adverse modification of critical habitat.

To be included in a critical habitat designation, the habitat within the area occupied by the species must first have features that are essential to the conservation of the species. The Service must identify, to the extent known using the best scientific data available, habitat areas that provide essential life cycle needs of the species (areas on which are found the Primary Constituent Elements (PCEs), as defined at 50 CFR 424.12(b)). To be included in the designation, the features at issue must also be ones that may require special management considerations or protection.

Under the Act, we can designate unoccupied areas as critical habitat only when we determine that the best available scientific data demonstrate that the designation of that area is essential to the conservation needs of the species.

Section 4 of the Act requires that we designate critical habitat on the basis of the best scientific and commercial data available. Furthermore, our Policy on Information Standards Under the Endangered Species Act (published in the Federal Register on July 1, 1994 (59 FR 34271)), the Information Quality Act (section 515 of the Treasury and General Government Appropriations Act for Fiscal Year 2001 (Pub. L. 106554; H.R. 5658)), and our associated Information Quality Guidelines provide criteria, establish procedures, and provide guidance to ensure that our decisions represent the best scientific data available. They require our biologists, to the extent consistent with the Act and with the use of the best scientific data available, to use primary and original sources of information as the basis for recommendations to designate critical habitat.

When we are determining which areas we should as critical habitat, our primary source of information is generally the information developed during the listing process for the species. Additional information sources may include the recovery plan for the species, articles in peerreviewed journals, conservation plans developed by States and counties, scientific status surveys and studies, biological assessments, or other unpublished materials and expert opinion or personal knowledge.

Habitat is often dynamic, and species may move from one area to another over time. Furthermore, we recognize that designation of critical habitat may not include all of the habitat areas that we may eventually determine, based on scientific data not now available to the [[Page 31123]]
Service, are necessary for the recovery of the species. For these reasons, a critical habitat designations does not signal that habitat outside the designated area is unimportant or may not be required for recovery of the species.

Areas that support populations, but are outside the critical habitat designation, will continue to be subject to conservation actions we implement under section 7(a)(1) of the Act. They are also subject to the regulatory protections afforded by the section 7(a)(2) jeopardy standard, as determined on the basis of the best available scientific information at the time of the agency action. Federally funded or permitted projects affecting listed species outside their designated critical habitat areas may still result in jeopardy findings in some cases. Similarly, critical habitat designations made on the basis of the best available information at the time of designation will not control the direction and substance

FOR FURTHER INFORMATION CONTACT

Cary Norquist, Acting Field Supervisor, Mississippi Fish and Wildlife Office at 6578 Dogwood View Parkway, Suite A, Jackson, MS 39213 (telephone 6013211122; facsimile 6019654340). If you use a telecommunications device for the deaf (TDD), you may call the Federal Information Relay Service (FIRS) at 8008778339.

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