Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for the Georgia Pigtoe Mussel, Interrupted Rocksnail, and Rough Hornsnail and Designation of Critical Habitat, 67512-67550 [2010-27417]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 75, Number 211 (Tuesday, November 2, 2010)]
[Rules and Regulations]
[Pages 67512-67550]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-27417]



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Part III





Department of the Interior





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Fish and Wildlife Service



50 CFR Part 17



Endangered and Threatened Wildlife and Plants; Determination of 
Endangered Status for the Georgia Pigtoe Mussel, Interrupted Rocksnail, 
and Rough Hornsnail and Designation of Critical Habitat; Final Rule

Federal Register / Vol. 75, No. 211 / Tuesday, November 2, 2010 / 
Rules and Regulations

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R4-ES-2008-0104; MO 92210-0-0008-B2]
RIN 1018-AU88


Endangered and Threatened Wildlife and Plants; Determination of 
Endangered Status for the Georgia Pigtoe Mussel, Interrupted Rocksnail, 
and Rough Hornsnail and Designation of Critical Habitat

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), list the 
Georgia pigtoe mussel (Pleurobema hanleyianum), interrupted rocksnail 
(Leptoxis foremani), and rough hornsnail (Pleurocera foremani) as 
endangered under the Endangered Species Act of 1973, as amended (Act). 
We also designate approximately 258 kilometers (km) (160 miles (mi)) of 
stream and river channels as critical habitat for the three species, in 
Cherokee, Clay, Coosa, Elmore, and Shelby Counties, Alabama; Gordon, 
Floyd, Murray, and Whitfield Counties, Georgia; and Bradley and Polk 
Counties, Tennessee.

DATES: This rule becomes effective on December 2, 2010.

ADDRESSES: This final rule and final economic analysis are available on 
the Internet at https://www.regulations.gov. Comments and materials 
received, as well as supporting documentation used in preparing this 
final rule are available for public inspection, by appointment, during 
normal business hours, at the U.S. Fish and Wildlife Service, Jackson 
Ecological Services Field Office, 6578 Dogwood View Parkway, Suite A, 
Jackson, MS 39213 (telephone 601-321-1122; facsimile 601-965-4340).

FOR FURTHER INFORMATION CONTACT: Stephen Ricks, Field Supervisor, U.S. 
Fish and Wildlife Service, Jackson Ecological Services Field Office 
(see ADDRESSES section). If you use a telecommunications device for the 
deaf (TDD), call the Federal Information Relay Service (FIRS) at 800-
877-8339.

SUPPLEMENTARY INFORMATION: This document consists of: (1) A final rule 
to list as endangered the Georgia pigtoe mussel (Pleurobema 
hanleyianum), interrupted rocksnail (Leptoxis foremani), and rough 
hornsnail (Pleurocera foremani); and (2) a final rule to designate 
critical habitat for each of these three species.

Previous Federal Action

    Federal actions for these species prior to June 29, 2009 are 
outlined in our proposed rule for these actions (74 FR 31113). 
Publication of the proposed rule opened a 60-day comment period, which 
closed on August 28, 2009. We reopened the comment period from February 
10, 2010, through March 12, 2010, in order to announce the availability 
of and receive comments on a draft economic analysis (DEA), and to 
extend the comment period on the proposed listing and designation to 
accommodate a public hearing (75 FR 6613).

Public Comments

    We received comments from the public on the proposed listing action 
and proposed critical habitat designation, and, in this rule, we 
respond to these issues in a single comments section. Below, we present 
the listing analysis first, followed by the analysis for designation of 
critical habitat.

Background

    It is our intent to discuss only those topics directly relevant to 
the listing and designation of critical habitat for the Georgia pigtoe 
mussel (Pleurobema hanleyianum), interrupted rocksnail (Leptoxis 
foremani), and rough hornsnail (Pleurocera foremani). For information 
on our proposed determination, refer to the proposed rule published in 
the Federal Register on June 29, 2009 (74 FR 31113).

Georgia Pigtoe Mussel

    The Georgia pigtoe (Pleurobema hanleyianum) is a freshwater mussel 
in the family Unionidae. It was described in 1852 by Lea as Unio 
hanleyianum from the Coosawattee River in Georgia. The species 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. 719-721).
    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 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 yellowish-tan to reddish-brown and may 
have concentric green rings. The beak cavity is shallow, and the shell 
interior is white to dull bluish-white (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 sand-gravel-cobble bottoms. 
Unionid mussels, such as the Georgia pigtoe, filter-feed 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 hosts 
for 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, and 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) in litt. 
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 (Gangloff in litt. 2006).
    In 1990, the Service initiated a status survey and reviewed 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. 1-27; Hartfield in litt. 
1990-2001). 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.

[[Page 67513]]

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 (Hartfield in litt. 2004; Williams and 
Hughes 1998, pp. 2-6; Johnson and Evans 2000, p. 106; Herod et al. 
2001, pp. i-ii; Gangloff 2003, pp. 11-12; McGregor and Garner 2004, pp. 
1-18; 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. 11-12, 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. 33-34). All recent collection sites occur within a 43-km (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 small-to-medium-
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 ornamented by partial costae (folds in the 
surface). The shell is subglobose (not quite spherical); thick, dark 
brown to olive in color; occasionally spotted; and generally covered 
with fine striae (longitudinal ridges). 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. 18-19, 21-23). 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. 45-46); 
however, Burch (1989, p. 155) had previously placed L. downei within L. 
foremani as an ecological variant. 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). 
In a hatchery setting, mean clutch size for 2-year-old interrupted 
rocksnails is around 8.83 (3 to 18 eggs per clutch), and clutch size of 
females greater than 3 years is 13.63 (2 to 21 eggs per clutch) 
(Johnson in litt. 2009). 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 
silt-free 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 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 in litt. 2006).
    Snail surveys conducted within the historical range of the 
interrupted rocksnail (Bogan and Pierson 1993a, pp. 1-27; Williams and 
Hughes 1998, pp. 1-21) 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 Gordon and Floyd County line (Johnson and Evans 2000, 
pp. 45-46; 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. 1-4). 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; 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 
search-hours in 2004 (Johnson in litt. 2003, 2004). The cause of 
decline was suspected to be some form of water contamination (Johnson 
in litt. 2003, 2004; Hartfield in litt. 2006). A July 2006 search for 
adults to use as hatchery stock failed to locate any rocksnails in more 
than 2 search-hours (Hartfield in litt. 2006). However, a subsequent 
search in August 2006 under lower flow conditions resulted in the 
location of 89 snails in 4 search-hours at one shoal,

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and 2 rocksnails in 4 search-hours at another shoal (Johnson in litt. 
2007a).
    Since their reintroduction into the Lower Coosa River of Alabama, a 
few of the 2003 hatchery-cultured 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 (Pierson in litt. 2005). 
During a 40-minute search of this release area in 2006, two interrupted 
rocksnails were found (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 yellowish-brown whorls. The aperture is 
elongated, angular, channeled at the base, and usually white inside. 
The presence of a double row 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. In a hatchery setting, 
however, the distinctive double row of tubercules do not appear until 
the second year of life (5 to 7 mm shell width) (Johnson in litt. 
2009).
    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. 21-22, 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 co-occurring 
species in the genus Elimia, and concluded that it should be recognized 
as Elimia foremani (Sides 2005, pp. 26-27). Although the Sides (2005, 
pp. 26-27) study provides some evidence that this species should be 
placed in the genus Elimia, this taxonomic change has not been formally 
peer-reviewed 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, bedrock, 
and mud 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 low-to-moderate 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. 26-27), 
whereas Elimia snails generally lay eggs in short strings (P. Johnson 
pers. comm. 2006). Although some attempts to induce rough hornsnails to 
lay eggs in captivity have been unsuccessful (Sides 2005, p. 27), 
others have observed females laying eggs individually or in short 
``strips'' (3 to 10 eggs) during late April into July (Johnson in litt. 
2009). Cultured rough hornsnails have become reproductively active in 
their second year (Johnson in litt. 2009). Some adult individuals 
collected from the wild have survived in captivity for 3 years, 
suggesting a life span of 4 to 5 years (Garner in litt. 2009, Johnson 
in litt. 2009).
    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 site-specific records of 
the rough hornsnail that validate its range into the State of Georgia 
(Johnson in litt. 2006a). Historical museum records of the rough 
hornsnail in the Coosa River (FLMNH in litt. 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 in Calhoun County; Choccolocco and 
Peckerwood Creeks in Talladega County; Yellowleaf Creek in Shelby 
County; and Yellow Leaf Creek in Chilton County (FLMNH in litt. 2006).
    The rough hornsnail is currently known to occur at two locations: 
Lower 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 in litt. 2006); however, the species has not 
been collected from this shoal reach in recent surveys (Johnson 2002, 
pp. 5-9). Yellowleaf Creek is a moderately sized stream where rough 
hornsnails were, until recently, only known from about a 50-m (55-yd) 
length of the stream. At this location, rough hornsnails occur at 
densities of 8 to 32 per m\2\ (1.2 per yd\2\) (Pierson in litt. 2006). 
Following publication of the proposed rule (74 FR 31113, June 29, 
2009), an intensive survey of Yellowleaf Creek extended the range of 
rough hornsnails in this stream to about 1.6 km (1 mi) above and below 
the previously known site (Powell in litt. 2009). The Lower Coosa River 
is a large river channel where rough hornsnails have recently been 
found in two discrete areas (Hartfield pers. obsv. 2001, Crow in litt. 
2008). No quantitative estimates have been made at these sites; 
however, at one site, rough hornsnail numbers were estimated at 300 to 
400 individuals (Crow in litt. 2008). Searches of unimpounded reaches 
of the Coosa River and the lower portions of tributaries to the Coosa 
River have failed to locate the species elsewhere (Bogan and Pierson 
1993a, pp. 1-27; Garner, pers. comm. 2005; Hartfield in litt. 2006). 
The two known surviving populations are separated by three impoundments 
and about 113 km (70 mi) of unsuitable, impounded channel habitat.

Summary of Comments and Recommendations

    During the open comment periods for the proposed rule (74 FR 
31113), draft economic analysis, and public hearing (75 FR 6613), we 
requested all interested parties submit comments or information 
concerning the proposed

[[Page 67515]]

listing and designation of critical habitat for the three mollusks. We 
contacted all appropriate State and Federal agencies, county 
governments, elected officials, scientific organizations, and other 
interested parties and invited them to comment. We also published 
newspaper notices inviting public comment in the following newspapers: 
Cherokee County Herald, Centre, AL; Daily Home, Talladega, AL; The 
Wetumpka Herald, Wetumpka, AL; Chatsworth Times, Chatsworth, GA; Rome 
News Tribune, Rome, GA; The Daily Citizen, Dalton, GA; The Calhoun 
Times, Calhoun, GA; Cleveland Daily Banner, Cleveland, TN; and Polk 
County News, Benton, TN.
    We directly notified and requested comments from all affected 
States. The State of Alabama provided additional records of one 
species. None of the States expressed a position on the actions. During 
the comment periods, we received a total of 16 comments from one State 
agency, two Federal agencies, eight groups, and three individuals. At 
the public hearing, we received three oral comments. A transcript of 
the hearing is available for inspection at the Jackson, Mississippi 
Ecological Services Field Office (see ADDRESSES section).

Peer Review

    In accordance with our peer review policy published in the Federal 
Register on July 1, 1994 (59 FR 34270), we requested the expert 
opinions of four knowledgeable individuals with expertise on freshwater 
mollusks, the Mobile River Basin, and conservation biology principles. 
The purpose of such review is to ensure that the designation is based 
on scientifically sound data, assumptions, and analyses, including 
input of appropriate experts and specialists.
    We received written responses from three of the peer reviewers. All 
peer reviewers stated that the proposal included a thorough and 
accurate review of the available scientific and commercial data on 
these mollusks and their habitats. One peer reviewer provided 
additional details and minor corrections on the shell descriptions of 
the interrupted rocksnail and rough hornsnail. Two reviewers provided 
information on clutch size and life span of rough hornsnail. One 
reviewer noted the collection of rough hornsnail on mud bottoms, and 
recommended including this in the discussion of the physical and 
biological features that are essential to the conservation of that 
species (primary constituent elements (PCEs)). This information 
provided by the reviewers has been incorporated into the appropriate 
sections of this final rule. One peer reviewer suggested additional 
stream reaches that could be designated as critical habitat for each of 
the three species. These suggestions are discussed below.
    We reviewed all comments received for substantive issues and new 
data regarding the three mollusks, their critical habitats, and the 
draft economic analysis. Written comments and oral statements presented 
at the public hearing and received during the comment periods are 
addressed in the following summary. For readers' convenience, we have 
combined similar comments into single comments and responses.

Peer Reviewer Comments

    (1) Comment: The Georgia pigtoe survives in only 3 to 5 miles (4.8 
to 8 kilometers) of the Conasauga River, and has been extirpated from 
more than 99.9 percent of its historic range.
    Our response: Over the past 20 years, the Georgia pigtoe has been 
collected from two localized collection sites on the Conasauga River, 
one at each extreme of a 43-km (27-mi) reach of the river. We have 
considered this entire reach as occupied because of the similarity of 
habitat within this reach, and the potential of the species to occur 
within any portion of the reach.
    (2) Comment: Big Canoe, Choccolocco, and Weogufka Creeks should be 
designated as critical habitat for Georgia pigtoe.
    Our response: While Big Canoe, Choccolocco, and Weogufka Creeks are 
within the geographical range of the Georgia pigtoe and appear to be 
suitable for the species, we are unaware of any verified historical 
records of the species from these three tributaries. Although we have 
not included these areas as critical habitat in this final rule, they 
are within the geographical range of the species and may prove to be 
important in the future to the conservation of the species.
    (3) Comment: Choccolocco, Hatchet, and Terrapin Creeks should be 
designated as critical habitat for the interrupted rocksnail.
    Our response: Choccolocco, Hatchet, and Terrapin Creeks are within 
the geographical area historically occupied by the interrupted 
rocksnail. Most museum specimens and historical records of interrupted 
rocksnail were from the mainstem Coosa River and larger tributaries 
(Oostanaula, Coosawhattee, Conasauga, and Etowah Rivers), and we were 
able to document records of interrupted rocksnail from the lower reach 
of Terrapin Creek. It is also likely that some populations extended 
into the lower reaches of some other tributaries. However, this species 
requires moderate to high stream flow, and the lower reaches of 
Choccolocco and Hatchet Creeks have little flow, due to embayment by 
Coosa River reservoirs. As a result, we did not include these areas as 
critical habitat in this final rule. Lower Terrapin Creek continues to 
experience natural flow, and will be available to colonization if the 
species is successfully reintroduced into Unit IR 1.
    (4) Comment: Recent sampling has extended the range of the rough 
hornsnail in Yellowleaf Creek.
    Our response: Following publication of the proposed rule and 
closure of the first comment period, a snail survey of lower Yellowleaf 
Creek was conducted by biologists from the Service, ADCNR, and Alabama 
Power Company. The rough hornsnail was found at several sites within 
the upper and lower limits of the proposed critical habitat. The 
information that the rough hornsnail currently inhabits all of the area 
within Unit RH 2, Yellowleaf Creek, has been incorporated into the 
Background and Critical Habitat sections of this final rule.
    (5) Comment: Choccolocco Creek, Kelly Creek, and the Coosa River 
below Logan Martin Dam in the vicinity of the confluence of Kelly Creek 
should be included as critical habitat for the rough hornsnail.
    Our response: We identified two areas with greatest conservation 
potential for the rough hornsnail, Lower Coosa River (Unit IR 1) and 
Yellowleaf Creek (Unit IR 2), as both of these units contain unoccupied 
habitat adjacent to occupied areas, with the potential of natural 
dispersal and recolonization. Lower Choccolocco Creek was considered to 
have minimal conservation potential for the species at this time 
because it is embayed by Logan Martin Lake, and is on the Alabama 
303(d) list of impaired waters. Kelly Creek, and the short associated 
reach of the Coosa River, is remote from currently occupied areas. 
Although this area was not included in the critical habitat designation 
for rough hornsnail, it may become important for the conservation of 
the species at some point in the future.

Comments from States

    (6) Comment: There are records of Georgia pigtoe from Kelly, Big 
Canoe, and Choccolocco Creeks that were not acknowledged in the 
historical distribution.
    Our response: It is probable that any large Coosa River tributary 
may have supported historical populations of the Georgia pigtoe at some 
time in the past. We have relied on published records and museum 
specimens to confirm the species' historical presence for purposes

[[Page 67516]]

of this critical habitat designation. Some historical Coosa River 
tributary records, however, have been found to be misidentifications of 
other closely related species, and we were unable to document any 
historical records of Georgia pigtoe from Kelly, Big Canoe, and 
Choccolocco Creeks.

Public Comments

    (7) Comment: The conclusions supporting the proposed designation of 
the critical habitat units are not supported by data or sound science. 
The Act requires the Service to refrain from designating critical 
habitat when the biological needs of the species are not sufficiently 
well known to permit identification of an area as critical habitat 
(citing Cape Hatteras Access Preserv. Alliance v. U.S. Dept. Int., 344 
F. Supp. 2nd 108, 123 (D.D.C. 2004)).
    Our response: We determined that, based on the best available 
scientific and commercial data, sufficient information is available to 
identify physical and biological features essential to the conservation 
of the species and specific areas that meet the definition of critical 
habitat (see Primary Constituent Elements (PCEs) section).
    In the case cited by the commenter, the Service had not identified 
any features essential to the conservation of the species (primary 
constituent elements (PCEs)) within some portions of a broad critical 
habitat designation for piping plover, but argued that designation was 
proper because PCEs would likely be found in the future. The court 
found that this was ``beyond the pale of the [Act].'' In contrast, in 
both the proposed and this final rule, we identified PCEs within the 
designated habitat (see Criteria Used To Identify Critical Habitat, and 
Critical Habitat Designation sections). Therefore, we have complied 
with the requirements of the Act.
    (8) Comment: The Service exceeded the statutory basis for proposing 
to designate Units GP2 and IR1 as unoccupied critical habitat by 
including the potential for minimum flows as baseline criteria for the 
establishment of the units. The Act does not provide for special 
management or operational considerations for proposed units that are 
presently unoccupied by target species (citing Cape Hatteras Access 
Preserv. Alliance v. U.S. Dept. Int., 344 F. Supp. 2nd 108, 123 (D.D.C. 
2004)).
    Our response: In the case cited by the commenter, the Service 
included areas that clearly did not contain PCEs within a broad 
critical habitat designation for piping plover. The Court determined 
that the Service must show that PCEs, which may in the future require 
special consideration or management, are found on the areas it 
designated as critical habitat.
    In this designation, when considering areas as critical habitat, we 
assessed whether the areas contained features that are essential to the 
conservation of the species (PCEs) and whether those features may 
require special management considerations or protections. The presence 
of one or more PCE was documented (see Critical Habitat Designation 
section) in all of the stream reaches designated as unoccupied critical 
habitat for the Georgia pigtoe, interrupted rocksnail, and rough 
hornsnail. We use the language ``* * * one or more * * *'' in 
recognition that all areas essential to the conservation of a species 
may not contain all PCEs, based on the biology of the species. For 
example, a species may require one area for feeding and growing, 
another for reproduction or roosting, and still other areas for passage 
between feeding and growing areas. So while all areas may not contain 
the same constituent elements, they may be important at some life stage 
or during some time of the year and collectively they are essential to 
the conservation of the species.
    Unit GP 2 for the Georgia pigtoe includes the lower reach of 
Terrapin Creek, downstream to its confluence with the Coosa River, and 
the Coosa River from Weiss Dam downstream to a point below the 
confluence of Terrapin Creek in Cherokee County, Alabama (see Critical 
Habitat Designation, Unit GP 2, below). All five PCEs identified for 
Georgia pigtoe are present in Terrapin Creek and in the Coosa River 
portion of Unit GP 2 below the confluence of Terrapin Creek. Unit IR 1 
for the interrupted rocksnail includes the Coosa River channel between 
Weiss Dam to a point below the confluence of Terrapin Creek (see 
Critical Habitat Designation, Unit IR 1, below). All four PCEs 
identified for the interrupted rocksnail are present in the Coosa River 
portion of the Unit below Terrapin Creek. Two of the five PCEs for 
Georgia pigtoe, and two of the four PCEs for interrupted rocksnail, are 
currently present in the Coosa River portion of the units between Weiss 
Dam and the confluence of Terrapin Creek. Minimum flows are projected 
to be released from Weiss Dam as part of a Federal Energy Regulatory 
Commission relicensing agreement in the near future that will restore 
the remaining PCEs for both of these species in this portion of the 
reach, but that was not the sole basis for this designation.
    (9) Comment: It is unreasonable to designate unoccupied areas 
adjacent to current populations as critical habitat in light of the 
Service's lack of knowledge of specific habitat requirements.
    Our response: All recent records of the Georgia pigtoe, interrupted 
rocksnail, and rough hornsnail are extremely localized. Because rare 
aquatic snails and mussels can be difficult to locate, where more than 
one occurrence record of a particular species was found within a stream 
reach, we considered the entire reach between the uppermost and 
lowermost locations as occupied habitat. We then considered the 
adequacy of occupied habitat for conservation of the species, and 
determined that designating only occupied habitat would not be 
sufficient to conserve each of these species (see Criteria Used To 
Identify Critical Habitat section). For identification of unoccupied 
areas essential to the conservation of the species, we established six 
criteria for their consideration (see Stream Reaches Not Currently 
Occupied section), including the presence of PCEs. One of these 
criteria prioritized stream reaches adjacent to currently occupied 
areas. These reaches are similar in stream size, geology, and water 
quality to adjacent occupied areas, and we believe that it is 
reasonable and cost effective to protect areas available for natural 
dispersal and reoccupation.
    (10) Comment: Critical habitat designation of currently uninhabited 
areas remote from occupied areas (Units GP 2, GP 3, IR 1, IR 3) is not 
supported by the record, and would be arbitrary and capricious because 
there is no analysis, data, or discussion whether released, captive-
bred stock can become self-sustaining.
    Our response: Many endangered aquatic mollusks are so rare that 
relocations are not an option (National Native Mussel Conservation 
Committee 1997, p. 8). However, freshwater mussels, including 
endangered and threatened species, have been relocated with some 
success from areas of disturbance into new habitats (Cope and Waller 
1995, p. 147; U.S. Fish and Wildlife Service 2004, p. 4). Attempts to 
relocate imperiled mollusks from areas of natural abundance into 
historical habitats have also been successful (e.g., Ahlstedt 1991, p. 
141). Aquatic mollusk hatchery husbandry is a relatively new science. 
However, much progress has been made over the past 2 decades and 
hatchery propagation of aquatic mollusks is now a viable conservation 
tool (e.g., Freshwater Mollusk Conservation Society 2006, p. 1-13). 
Reintroduction with hatchery propagules is recognized as a primary 
recovery task for rare aquatic species in the Mobile River Basin 
Aquatic

[[Page 67517]]

Ecosystem Recovery Plan (U.S. Fish and Wildlife Service 2000, p. 30). 
As noted in the Background, above, the interrupted rocksnail has been 
successfully propagated and produced in sufficient numbers for limited 
releases. Another closely related snail, the plicate rocksnail, has 
been propagated, and attempts to reintroduce the species into 
historical habitat in Alabama have shown success in terms of survival 
and natural recruitment in the reintroduced population (Johnson in 
litt. 2008). The available information indicates that the Georgia 
pigtoe and interrupted rocksnail cannot be conserved without extending 
the species' range into historically occupied areas (see Criteria Used 
To Identify Critical Habitat section). Reintroduction using hatchery 
reared offspring is currently the only option to achieve this 
conservation benchmark.
    (11) Comment: The Act and its application in designating critical 
habitat is unconstitutional in light of the clear limitations on the 
use of Federal power in the property clause of the Constitution's Fifth 
Amendment (``* * * private property [shall not] be taken for public 
use, without just compensation'').
    Our response: The designation of critical habitat, in and of 
itself, has no legal effect on property rights or constitute a physical 
or regulatory ``taking'' of real estate property. Critical habitat does 
not preclude property use; rather, it only affects Federal 
authorization or funding of projects that may adversely modify critical 
habitat. In the event such a finding is made in a section 7 
consultation with the Federal funding or authorizing agency, the 
Service is required to identify reasonable and prudent project 
alternatives. Exemption procedures under the Act provide sufficient 
opportunity to accomplish the Service's statutory mandates without 
precluding compatible use of private property. Therefore, critical 
habitat designation, by itself, does not affect a taking of private 
property.
    (12) Comment: FWS should conduct an analysis under the National 
Environmental Policy Act (NEPA) (42 U.S.C. 4321 et seq.) prior to 
listing and designating critical habitat.
    Our response: Environmental assessments and environmental impact 
statements, as defined under NEPA, are not required for regulations 
enacted under section 4 of the Act (see 48 FR 49244, October 25, 1983). 
The FWS has determined that, outside of the jurisdiction of the United 
States Court of Appeals for the Tenth Circuit, a NEPA analysis is not 
required for critical habitat designation.
    (13) Comment: Interrupted rocksnails in Alabama (Unit IR 3) that 
are covered by the proposal are not wild, naturally occurring species. 
The reintroduced colony is not reproducing and is not viable.
    Our response: Any interrupted rocksnails currently surviving in 
Unit IR 3 are surviving individuals from releases made by ADCNR in 2003 
through 2005, or their offspring. While there is currently no evidence 
that natural recruitment of rocksnails has occurred on the shoal since 
the release, we are unable to confirm their extirpation from the site. 
Including this single shoal in the designation alerts Federal action 
agencies to the species' potential presence.
    (14) Comment: The determination that reintroduction of interrupted 
rocksnail into Units IR 1 and IR 3 is essential to its conservation is 
not supported by the record and is arbitrary and capricious.
    Our response: Under the Summary of Factors Affecting the Species 
section, below, we note that the surviving populations of each species 
are small, extremely localized, isolated, and vulnerable to habitat 
modification, toxic spills, progressive degradation from land surface 
runoff, and catastrophic changes to their habitats from flood scour and 
drought. Under the Criteria Used To Identify Critical Habitat section, 
we discuss areas currently occupied by the species, the species' 
limited extent, their vulnerability to random events, and the inability 
of these species to naturally recolonize historically occupied areas 
that might now support them. This information was used to determine 
that the designation of unoccupied critical habitat is essential to the 
conservation of the species. Also under the Criteria Used To Identify 
Critical Habitat section, we discuss our process for assessing the 
potential of historically occupied stream reaches as unoccupied 
critical habitat, the criteria we used to determine if they were 
essential to the conservation of the species, and the PCEs currently 
present in each stream reach considered for designation as critical 
habitat. Our reasons for designating Units IR 1 and IR 3 as critical 
habitat for the interrupted rocksnail are discussed in some detail in 
the Critical Habitat sections, below. These include the presence of 
PCEs in both units, the presence of species in both units that are 
closely related to the interrupted rocksnail and require similar PCEs, 
improvements in water quality and quantity over the past 2 decades, and 
the potential of these two stream reaches for reoccupation by the 
interrupted rocksnail through reintroduction efforts. Based on this 
analysis, and our review of the best available scientific information, 
all unoccupied stream reaches included in the critical habitat 
designations for each of these three species, including Units IR 1 and 
IR 3, are essential to their conservation. Units IR 1 and IR 3, 
however, are remote and separated by one (Unit IR 1) or more (Unit IR 
3) impoundments from the only surviving population of the interrupted 
rocksnail in the Oostanaula River. Therefore, conservation of the 
interrupted rocksnail will require reintroduction of the species into 
Unit IR 1, and appropriate areas in Unit IR 3.
    (15) Comment: Smaller and more protected tributaries should be 
considered for reintroductions of the interrupted rocksnail.
    Our response: While smaller and more protected tributaries are 
within the historical geographical range of the interrupted rocksnail, 
and may become important to its conservation, we relied on documented 
historically occupied areas for the purposes of preparing this critical 
habitat designation for the reasons discussed above (see our response 
to Comment 6, above).
    (16) Comment: There are no rough hornsnails in the habitat proposed 
to be designated as critical habitat.
    Our response: Rough hornsnails were documented from Unit RH 1, 
Coosa River above the Fall Line during the 1990s (FLMNH in litt. 2006), 
and have most recently been documented from two locations below the 
Fall Line (Hartfield in litt. 2001, Crow in litt. 2008). In Unit RH 2, 
Yellowleaf Creek, rough hornsnails occur throughout the designated 
reach (see Background section).
    (17) Comment: The Service appears to be proposing to designate 
critical habitat on the chance a particular species might move into it 
at some point in the future. What happens to unoccupied critical 
habitat if a species does not naturally repopulate the area?
    Our response: With appropriate management, we hope to conserve the 
Georgia pigtoe, interrupted rocksnail, and rough hornsnail within 
currently occupied areas and promote natural dispersal into unoccupied 
areas adjacent to occupied reaches. We recognize that there is little 
chance of natural dispersal of the Georgia pigtoe and interrupted 
rocksnail into the designated unoccupied areas that are remote from 
surviving populations due to the presence of multiple dams and large 
areas of impounded (and thus unsuitable) channels. However, newly

[[Page 67518]]

developed information and technology are promising for successful 
reintroductions of hatchery-reared individuals into these areas.
    (18) Comment: What happens to critical habitat if a species becomes 
definitively extinct?
    Our response: The Act requires us to conduct 5-year reviews on the 
status of listed species. If a species is determined to be extinct, it 
can be removed from the List of Endangered and Threatened Wildlife 
through the formal rulemaking process. If a species is removed from the 
List due to extinction, areas that have been designated as critical 
habitat for that species will no longer be subject to the section 7 
consultation requirements of the Act.
    (19) Comment: The Service did not consider whether the reintroduced 
population of interrupted rocksnail present in Unit IR 3 should be 
designated as experimental under section 10(j) of the Act. Listing and 
designating critical habitat for reintroduced species is bad public 
policy, and is an attempt to circumvent the purposes of section 10(j) 
of the Act.
    Our response: Under section 10(j), the Secretary of the Department 
of the Interior can designate reintroduced populations established 
outside the species' current range, but within its historical range, as 
``experimental.'' Based on the best available information, we must 
determine whether an experimental population is ``essential'' or 
``nonessential'' to the continued existence of the species. 
Experimental populations that are essential to the continued existence 
of the species are treated as a threatened species, and the Secretary 
may promulgate regulations under section 4(d) of the Act. Experimental 
populations that are not essential to the continued existence of the 
species are treated as species proposed for listing. Section 
10(j)(C)(ii) prohibits designation of critical habitat only for 
experimental populations that are not essential to the continued 
existence of the species.
    Within this rule, we reviewed the status of the interrupted 
rocksnail, its historical and current range, the threats affecting the 
conservation of the species, and the areas available for its 
conservation. We used this information to identify Unit IR 3 as an area 
essential for the conservation of the interrupted rocksnail, and we are 
designating it as critical habitat (see Unit IR3: Lower Coosa River, 
Elmore County, Alabama, below).
    (20) Comment: The reintroduction of the interrupted rocksnail into 
Alabama prior to the proposed listing did not allow for consideration 
of the Act's reintroduction provisions, or alert the public to the 
Service's consideration of experimental status.
    Our response: As noted in our response to Comment 13, above, the 
reintroduction of the interrupted rocksnail into the lower Coosa River, 
Alabama, was a State action conducted under State regulations. The 
public was notified by the State through a press release and 
publication of the reintroduction in public media.
    (21) Comment: The Service recognizes (in the 2003 draft, Freshwater 
Mussels and Snails of the Mobile River Basin: Plan for the Controlled 
Propagation, Augmentation, and Reintroduction) that reintroductions of 
hatchery mollusk propagules is experimental in nature. Therefore, they 
should be designated as experimental populations under section 10(j) of 
the Act.
    Our response: The 2003 draft plan for controlled propagation was 
addressed to scientists, institutions, and agencies contemplating 
propagation of mollusks as a management strategy. In 2003, mollusk 
propagation was an emerging science and technology. This was the first 
propagation plan developed for mollusk species, and sought to alert the 
intended audience (i.e., scientists and State and Federal agencies 
contemplating propagation of mollusks) of the need for rigorous 
documentation and monitoring. The use of the term ``experimental'' in 
this document has no direct connection to the term's use under section 
10(j) of the Act, where it is a term used to identify reintroduced 
populations of listed species outside of their geographical range that 
may receive specific exemptions from section 9 of the Act.
    (22) Comment: The lack of experimental population designation for 
interrupted rocksnails (in IR 3) may cause serious negative impacts to 
landowners, businesses, and users of the Coosa River, through limiting 
landowners' ability to manage properties and creating uncertainty for 
landowners and waterway users.
    Our response: Unit IR 3 is occupied by the federally protected 
tulotoma snail and fine-lined pocketbook, which are currently subject 
to the section 7 consultation provisions, as well as the section 9 
prohibitions, of the Act. Apart from limited hydropower flow 
modifications to reduce take of tulotoma snail by the Alabama Power 
Company, we are unaware of any negative impacts to landowners, 
businesses, or users of this reach of the Coosa River due to the 
presence of mollusk species currently protected under the Act. It is 
not anticipated that this listing and the reintroduction of interrupted 
rocksnails will impair legal activities in the unit by landowners and 
waterway users.
    (23) Comment: The proposed critical habitat designation of 
unoccupied habitat for the interrupted rocksnail should be withdrawn.
    Our response: We are required by section 4(a) of the Act to 
designate critical habitat at the time a species is listed, and to 
designate unoccupied areas as critical habitat 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 (see 
Critical Habitat section). We determined that Unit IR 1 and unoccupied 
portions of Units IR 2 and IR 3 are essential to the conservation of 
the interrupted rocksnail (see Criteria Used to Identify Critical 
Habitat section).
    (24) Comment: The data in the proposed rule relative to released 
captive interrupted rocksnails are not consistent with ADCNR records. 
The proposed rule states that approximately 7,400 interrupted 
rocksnails were released into the Coosa River by the State of Alabama 
2003-2005, while information from ADCNR indicates that 10,476 
rocksnails were released during this same period.
    Our response: The numbers reported in the proposed rule were a 
typographical error. Records provided to us by TNARI and the State of 
Alabama document the release of 7,513 interrupted rocksnails into the 
Coosa River 2003-2005. We intended to state that approximately 7,500 
snails were released. TNARI records indicate around 10,476 snails were 
produced at its hatchery during 2003-2005. These production numbers may 
have been erroneously reported as released snails in a presentation by 
Dr. Paul Johnson (Johnson in litt. 2010).
    (25) Comment: The Service should develop a programmatic safe harbor 
agreement (SHA) to cover future releases of listed aquatic mollusks in 
Alabama.
    Our response: SHAs have been developed as tools to encourage 
private landowners and entities to implement conservation measures that 
maintain existing populations, encourage colonization by listed 
species, or expand existing populations. Programmatic SHAs have been 
developed to envelop multiple landowners under a single agreement, 
encouraging cooperative implementation and greatly reducing paperwork. 
SHAs and programmatic SHAs can be important conservation tools in 
recovering listed species, particularly in situations where the

[[Page 67519]]

cessation of voluntary conservation actions may result in take of 
listed species, and return their numbers to a pre-agreement baseline. 
We are willing to enter into SHAs, where appropriate, and where they 
would result in conservation benefits to the species.
    (26) Comment: Due to the lack of specific information on the 
biology of these species, the U.S. Army Corps of Engineers (Corps) 
could face operational restrictions (at Carters Reservoir) that have no 
relation to the conservation of the species.
    Our response: Under section 7 of the Act, the Corps will need to 
consult with us should their activities adversely affect the species or 
adversely modify their critical habitats. We have broadly defined 
activities that may destroy or adversely modify critical habitat below 
(see Application of the ``Adverse Modification'' Standard, below), and 
will work with the Corps to ensure that the best available information 
is used when they consult with us. Carters Reservoir is remote from any 
of the areas designated as critical habitat by this rule. The 
Coosawattee River below Carters Reservoir was designated as critical 
habitat for several mussel species in 2004 (see 69 FR 40084, July 1, 
2004). Our final economic analysis (Industrial Economics, Inc. 2010, 
pp. 3-6--3-10) found that there would only be incremental 
administrative costs associated with this listing and critical habitat 
designation and operations at Carters Reservoir.
    (27) Comment: What is the present need for designation of critical 
habitat and its related administrative costs at a time of severe 
economic difficulty?
    Our response: We are required by the Act to designate critical 
habitat, when prudent and determinable, at the time of listing. 
However, our economic analysis identified relatively small incremental 
costs that will occur due to this critical habitat designation 
(Industrial Economics, Inc. 2010). Specifically, incremental costs are 
anticipated to result entirely from the added administrative 
requirements of forecast section 7 consultations, and are estimated to 
be approximately $44,000 annually, assuming a 7 percent discount rate. 
These administrative costs are unlikely to have a significant effect on 
regional or national economic conditions.
    (28) Comment: The Service should avoid interference with barge 
transportation in the Alabama-Coosa-Tallapoosa (ACT) River system.
    Our response: The critical habitat designations in this rule are 
outside of or peripheral to areas used for barge transportation in the 
ACT River system. The economic analysis does not anticipate economic 
effects to barge transportation in the ACT River system as a result of 
this designation.
    (29) Comment: Speculation on future environmental flow releases at 
Carters Reservoir is pre-decisional, as the Corps' Water Control Manual 
update is not complete.
    Our response: The economic analysis draws on publically available 
information, as well as insights from professionals involved in water 
management in the ACT basin, to arrive at reasonable estimates of the 
future economic impacts of species conservation efforts on hydropower 
and other water management activities. The final economic analysis 
includes additional caveats with regard to impacts associated with 
potential environmental flow releases related to Corps facilities 
(Industrial Economics, Inc. 2010, pp. 3-6--3-10).
    (30) Comment: Critical habitat designation could impact power 
production, increase costs, and potentially have significant impacts to 
municipalities and cooperatives that benefit from hydropower.
    Our response: The potential effects of this designation on power 
production were considered in the economic analysis. The economic 
analysis finds that water managers at four hydroelectric production 
facilities in the ACT Basin are likely to undertake conservation 
efforts for listed species that will benefit the three mollusks, at an 
estimated cost of $8.8 million annually. Specifically, three facilities 
(Carters, Weiss, Jordan) are expected to modify operations to provide 
additional flows for the benefit of downstream aquatic species. 
However, these modifications related to conserving the Georgia pigtoe, 
interrupted rocksnail, and rough hornsnail are expected to occur absent 
these critical habitat designations, because the areas affected have 
been previously designated as critical habitat for, and are occupied 
by, other listed mollusk species with similar PCEs and habitat needs. 
Incremental economic impacts resulting from these critical habitat 
designations are expected to arise from expected administrative 
requirements of forecast section 7 consultations between Federal 
regulatory agencies and the Service (see our response to Comment 27, 
above).
    (31) Comment: The listing of the interrupted rocksnail and its 
critical habitat could have serious negative impacts on landowners, 
businesses, and users of the Coosa River system because it will require 
take avoidance and section 7 consultations for an activity that may 
affect the population or its critical habitat.
    Our response: The Act does not require analysis of the costs of 
designating species as endangered or threatened. The potential economic 
impacts associated with critical habitat designation for the 
interrupted rocksnail, as well as costs of protective measures for the 
species already expected to occur without proposed critical habitat 
designation, are presented in the economic analysis as baseline costs. 
Specifically, incremental costs are anticipated to result entirely from 
the added administrative requirements of forecast section 7 
consultations, and are estimated to be approximately $44,000 annually, 
assuming a 7 percent discount rate. Costs associated with future 
conservation efforts that may benefit the three mollusks in critical 
habitat areas are estimated to be $8.97 million to $9.16 million 
annually, assuming a 7 percent discount rate. Most (96 percent) of 
baseline costs quantified are conservation efforts related to potential 
lost hydropower production value at three facilities.

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.
    The following analysis examines all five factors currently 
affecting or that are likely to affect Georgia pigtoe, 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), interrupted rocksnail (Leptoxis 
foremani), and rough hornsnail (Pleurocera foremani) 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 section). The Georgia pigtoe has been 
eliminated from

[[Page 67520]]

more than 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 its 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 its 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 habitat loss was 
compounded by fragmentation and isolation of the remaining free-flowing 
portions of the Coosa River and its tributaries, as well as the 
species' 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. 261-264; McAllister et al. 2000, 
p. iii; Marcinek et al. 2005, pp. 20-21). 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. 63-64; Watters 1999, pp. 261-264; Marcinek et 
al. 2005, pp. 9-10). 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. 
63-64; Watters 1999, pp. 261-264; Marcinek et al. 2005, pp. 20-21). 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. 1-8; Bogan et al. 1995, pp. 250-251; Lydeard and Mayden 1995, pp. 
803-804; 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. 12-16).
    Dam construction on the Coosa River had a secondary effect of 
fragmenting the ranges of aquatic mollusk species, such as the Georgia 
pigtoe, interrupted rocksnail, and rough hornsnail, leaving relict 
habitats and populations isolated by the structures as well as by 
extensive areas of uninhabitable, impounded waters. Isolated 
populations were left more vulnerable to, and affected by, natural 
events (such as droughts), runoff from common land-use 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. 
64-71; U.S. Fish and Wildlife Service 2000, pp. 14-15). As a result, 
many relict populations became locally extirpated, and many mollusk 
species were driven to extinction (Bogan et al. 1995, pp. 250-251; 
Lydeard and Mayden 1995, pp. 803-804; Neves et al. 1997, pp. 54, 62; 
U.S. Fish and Wildlife Service 2000, pp. 6-9). 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 free-flowing 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 impoun