Endangered and Threatened Wildlife and Plants; Endangered Status for the Altamaha Spinymussel and Designation of Critical Habitat, 62928-62960 [2011-25539]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 76, Number 196 (Tuesday, October 11, 2011)]
[Rules and Regulations]
[Pages 62928-62960]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-25539]



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Vol. 76

Tuesday,

No. 196

October 11, 2011

Part III





Department of the Interior





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Fish and Wildlife Service





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50 CFR Part 17





 Endangered and Threatened Wildlife and Plants; Endangered Status for 
the Altamaha Spinymussel and Designation of Critical Habitat; Final 
Rule

Federal Register / Vol. 76 , No. 196 / Tuesday, October 11, 2011 / 
Rules and Regulations

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R4-ES-2008-0107; 92210 1111 0000-B2]
RIN 1018-AV88


Endangered and Threatened Wildlife and Plants; Endangered Status 
for the Altamaha Spinymussel 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, list the Altamaha 
spinymussel (Elliptio spinosa), a freshwater mussel endemic to the 
Altamaha River drainage of southeastern Georgia, as an endangered 
species under the Endangered Species Act of 1973, as amended (Act), and 
designate approximately 237.4 kilometers (km) (147.5 miles (mi)) of 
mainstem river channel as critical habitat in Appling, Ben Hill, 
Coffee, Jeff Davis, Long, Montgomery, Tattnall, Telfair, Toombs, Wayne, 
and Wheeler Counties, Georgia. This final rule will implement the 
Federal protections provided by the Act.

DATES: This rule becomes effective on November 10, 2011.

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, Georgia 
Ecological Services Office, 105 Westpark Dr., Suite D, Athens, GA 
30606; telephone 706-613-9493; facsimile 706-613-6059.

FOR FURTHER INFORMATION CONTACT: Sandra Tucker, Field Supervisor, U.S. 
Fish and Wildlife Service, Georgia Ecological Services Office (see 
ADDRESSES above). 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 the Altamaha spinymussel (Elliptio spinosa) as endangered; and 
(2) a final rule to designate critical habitat for this species.

Previous Federal Actions

    Federal actions for this species prior to October 6, 2010, are 
outlined in our proposed rule (75 FR 61664), which was published on 
that date. Publication of the proposed rule opened a 60-day comment 
period, which closed on December 6, 2010. We reopened the comment 
period from May 12, 2011, through June 13, 2011, 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 (76 FR 27629).

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

Species Description

    The Altamaha spinymussel (Elliptio spinosa) is a freshwater mussel 
in the family Unionidae, endemic to (found only in) the Altamaha River 
drainage of southeastern Georgia. The Altamaha River is formed by the 
confluence of the Ocmulgee and Oconee rivers and lies entirely within 
the State of Georgia. The species was described by I. Lea in 1836 from 
a site near the mouth of the Altamaha River in Darien, Georgia (Johnson 
1970, p. 303).
    This species reaches a shell length of approximately 11.0 
centimeters (cm) (4.3 inches (in)). The shell is subrhomboidal or 
subtriangular in outline and moderately inflated. As the name implies, 
the shells of these animals are adorned with one to five prominent 
spines. These spines may be straight or crooked, reach lengths from 1.0 
to 2.5 cm (0.39 to 0.98 in), and are arranged in a single row that is 
somewhat parallel to the posterior ridge. In young specimens, the 
outside layer or covering of the shell (periostracum) is greenish-
yellow with faint greenish rays, but as the animals get older, they 
typically become a deep brown, although some raying may still be 
evident in older individuals. The interior layer of the shell (nacre) 
is pink or purplish (Johnson 1970, p. 303).

Life History and Habitat

    Adult freshwater mussels are filter-feeders, siphoning 
phytoplankton, diatoms, and other microorganisms from the water column. 
For the first several months, juvenile mussels employ pedal (foot) 
feeding, extracting bacteria, algae, and detritus from the sediment 
(Yeager 1994, pp. 217-221; Cope et al. 2008, p. 457).
    Although the life history of the Altamaha spinymussel has not been 
studied, the life histories of other mussels in the Elliptio genus have 
been. Internal fertilization results in the female brooding the larvae 
(glochidia), which when mature are released. To ensure survival, 
glochidia must come into contact with a specific host fish or fishes to 
develop into juvenile mussels. Other mussels in the genus Elliptio are 
broadcast releasers, which may release conglutinates that resemble 
insect larvae. This reproductive strategy depends on clear water during 
the time of the year when mussels release their glochidia (Hartfield 
and Hartfield 1996, p. 375). The Altamaha spinymussel is thought to 
reproduce in late spring and release glochidia by May or June (Johnson 
2004, p. 2; Bringolf 2011, pers. comm.). The host fish of the Altamaha 
spinymussel is currently unknown. Furthermore, juvenile age classes of 
other mussels are commonly found during surveys; however, no 
spinymussel recruitment has been evident in surveys conducted since 
1990 (Keferl 2008, pers. comm.; Wisniewski 2008, pers. comm.). Research 
to develop a better understanding of the natural history and the 
reasons for a lack of recruitment in the species is continuing.
    This spinymussel is known only from Georgia in Glynn, Ben Hill, 
McIntosh, Telfair, Tattnall, Long, Montgomery, Toombs, Wheeler, 
Appling, Jeff Davis, Coffee, and Wayne Counties. This spinymussel is 
considered a ``big river'' species; is associated with stable, coarse-
to-fine sandy sediments of sandbars, sloughs, and mid-channel islands; 
and appears to be restricted to swiftly flowing water (Sickel 1980, p. 
12). Johnson (1970, p. 303) reported Altamaha spinymussels buried 
approximately 5.1 to 10.2 cm (2.0 to 4.0 in) below the substrate 
surface.

Species Distribution and Status

    The historical range of the Altamaha spinymussel was restricted to 
the Coastal Plain portion of the Altamaha River and the lower portions 
of its three major tributaries, the Ohoopee, Ocmulgee, and Oconee 
Rivers (Johnson 1970, p. 303; Keferl 2001, pers. comm.). Large-scale, 
targeted surveys for the mussel have been conducted since the 1960s 
(Keferl 1993, p. 299). Recent surveys have revealed a dramatic decline 
in recruitment, the number of populations, and number of individuals 
within populations throughout the species' historic range (Stringfellow 
and Gagnon 2001, pp. 1-2; Keferl 1995, pp.

[[Page 62929]]

3-6; Keferl 2008 pers. comm.; Wisniewski 2006, pers. comm.).
Ohoopee River
    In a survey of the Ohoopee River, Keferl (1981, pp. 12-14) found at 
least 30 live specimens of the Altamaha spinymussel at seven of eight 
collection sites, in thinly scattered beds, in the lower 8 kilometers 
(km) (5 miles (mi)) of the river. Spinymussels were not found higher in 
the watershed, presumably because there are insufficient flows to 
support this species. By the early 1990s, however, only two live 
specimens were found at the same sites (Keferl 1995, pp. 3-6; Keferl 
2008 pers. comm.; Wisniewski 2006, pers. comm.). Stringfellow and 
Gagnon (2001, pp. 1-2) resurveyed these sites using techniques similar 
to those used by Keferl (1981, p. 12), but did not find any live 
Altamaha spinymussels in the Ohoopee River. Therefore, the species is 
currently either extirpated from the Ohoopee River or present in such 
low numbers that it is undetectable.
Ocmulgee River
    The Altamaha spinymussel is known from the Ocmulgee River from its 
confluence with the Oconee River upstream to Red Bluff in Ben Hill 
County (approximately 110 km/68.3 mi). Early collecting efforts in the 
Ocmulgee River near Lumber City yielded many live Altamaha 
spinymussels. In 1962, Athearn made a single collection of 40 live 
spinymussels downstream of U.S. Highway 341 near Lumber City (Johnson 
et al. 2008, Athearn database). Researchers collected 19 and 21 live 
individuals, respectively, during two surveys at Red Bluff (Thomas and 
Scott 1965, p. 67). In 1986, Stansbery collected 11 live individuals at 
the U.S. Highway 441 Bridge near Jacksonville, Georgia (Wisniewski 
2006, pers. comm.).
    The lower Ocmulgee River was surveyed by Keferl in the mid 1990s, 
during 2000-2001 (Cammack et al. 2001, p. 11; O'Brien 2002, p. 2), and 
in 2004 (Dinkins 2004, pp. 1-1 and 2-1). Over 90 sites have been 
surveyed since 1993, many of which were repeatedly surveyed, resulting 
in a total of 19 live Altamaha spinymussels detected at 10 sites, 
distributed from Jacksonville downstream to the Oconee River 
confluence.
Oconee River
    There are few historical records of Altamaha spinymussels from the 
Oconee River. Athearn collected 18 spinymussels, including 5 juveniles, 
at a site in Montgomery County near Glenwood in the late 1960s (Johnson 
et al. 2008, Athearn database). The species has not been collected 
there since and is probably extirpated from the Oconee River system 
(Keferl 2008, pers. comm.). In 1995, as part of a dam relicensing 
study, 41 sites between Lake Sinclair and Dublin were surveyed (EA 
Engineering 1995, pp. 1-1, 3-1, 3-2, 4-2, and 4-3). One hundred forty-
four hours of search time yielded 118 live mussels, but no Altamaha 
spinymussels. Compared to the other portions of its range, the Oconee 
River has not been extensively surveyed, in part because the entire 
mussel fauna of this river appears to be sparse.
Altamaha River
    Most surveys for Altamaha spinymussels have been conducted in the 
Altamaha River. Although methodological differences preclude accurate 
comparison of mussel abundances over time, there is evidence that 
higher abundances of Altamaha spinymussels occurred in the Altamaha 
River historically. Early surveys at the U.S. Route 301 crossing 
documented 20 individuals in 1963, 7 in 1965, and 43 in 1970. Sickel 
sampled seven sites downstream of the U.S. Route 1 bridge in 1967. 
Sixty spinymussels were collected in one 500-square meters (m\2\) 
(5382-square feet (ft\2\)) site, and an additional 21 spinymussels were 
collected in a 400-m\2\ (4306-ft\2\) (Sickel 1980, p. 11; Wisniewski 
2006, pers. comm.) site. One site had five live spinymussels, two sites 
had one each, and two sites had no Altamaha spinymussels.
    From 1993 to 1996, Keferl surveyed 164 sites on the mainstem of the 
Altamaha River between the Ocmulgee-Oconee River confluence and the 
Interstate 95 crossing near the river's mouth (approximately 189 km/117 
mi.). A total of 63 live Altamaha spinymussels were collected from 18 
of these sites, located between the Oconee River and U.S. Route 301 
(116 km/72 mi); however, no Altamaha spinymussels were collected below 
U.S. Route 301 (73 km/45 mi), suggesting absence or extreme rarity in 
the reach between U.S. Route 301 and the river's mouth (approximately 
73 km (45 mi)). In addition, 10 of these sites were clustered within a 
4-km (2-mi) reach upstream of the U.S. Route 301 crossing near Jesup; 
the remaining eight sites were isolated by long distances of habitat 
with no or sub-detectable numbers of live spinymussels.
    O'Brien (2002, pp. 3-4) surveyed 30 sites on the Altamaha River 
from the confluence of the Ocmulgee and Oconee Rivers downstream to 
U.S. Route 301 during 2001, including the 18 known Altamaha spinymussel 
sites, reported by Keferl, within the reach. She collected a total of 
six live individuals from five different sites and freshly dead shells 
from two additional sites.
    In 2003 and 2004, researchers surveyed 25 sites to collect 
specimens for host-fish trials (Albanese 2005, pers. comm.). Live 
Altamaha spinymussels were detected at only four sites. Five of the 
seven sites documented by O'Brien and all four sites documented during 
the host-fish surveys were clustered within a short reach (15 km/24 mi) 
of the Altamaha River just upstream of the U.S. Route 301 crossing near 
Jesup, Georgia.
    To summarize, researchers were able to find 60 Altamaha 
spinymussels at a single site on the Altamaha River in 1967; in 
contrast, the largest number of Altamaha spinymussels observed from a 
single site on the Altamaha River during the 1990s or 2000s was nine 
(Albanese 2005, pers. comm.).
Summary of Basin-Wide Population Estimates
    In 1994, researchers spent 128 search-hours throughout the Altamaha 
Basin to find 41 spinymussels (Keferl 1995, p. 3). From 1997 through 
2006, researchers searched 233 sites throughout the basin to document 
34 spinymussels in more than 550 hours of searching (Wisniewski 2006, 
pers. comm.); from 2007 to 2009, only 23 spinymussels were found from 
more than 110 sites (Wisniewski 2009, pers. comm.). In summary, the 
Altamaha spinymussel is considered extirpated from two rivers in its 
historical range, the Ohoopee (15 km (9 mi)) and Oconee Rivers (45 km 
(28 mi)), as well as the lower 73 km (45 mi) of the Altamaha River 
(Table 1). Since 1997, despite extensive survey efforts made by several 
different researchers, only 57 spinymussels have been observed from 7 
sites in the Ocmulgee (110 km (68 mi)) and 15 sites in the upper 
Altamaha (116 km (72 mi)) combined, and while individual spinymussels 
have been found scattered throughout this stretch of river, most of 
these sites have been clustered in the 10 km (6 mi) immediately north 
of the U.S. Route 301 crossing.

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                              Table 1--Decline in Range of the Altamaha Spinymussel
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                                                                                                     Percent of
              River reach                  Historically  occupied           Current habitat          historical
                                               (linear km/mi)                                        range lost
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Ohoopee................................  15 km/9 mi...............  Not seen since 1997...........           4
Oconee.................................  45 km/28 mi..............  Not seen since 1968...........          12.5
Ocmulgee...............................  110 km/68.3 mi...........  Widely scattered..............           0
Upper Altamaha.........................  116 km/72 mi.............  Widely scattered individuals..           0
Lower Altamaha.........................  73 km/45 mi..............  Not seen since 1970...........          20
                                        ------------------------------------------------------------------------
    Total..............................  359 km/222 mi............  226 km/140 mi.................          36.5
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    Using Georgia Department of Natural Resources (GDNR)'s database, 
which included many of the surveys mentioned above, Wisniewski et al. 
(2005, p. 2) conducted a test for a temporal change in sites occupied 
in the Ocmulgee and Altamaha Rivers between the early 1990s and the 
early 2000s. Live Altamaha spinymussels were detected at 24 of 241 
sites (10 percent) sampled before 2000 and at 14 of 120 sites (12 
percent) sampled after 2000. Although the percentage of sites occupied 
is not indicative of a decline, an analysis of 39 sites sampled during 
both time periods, of which the spinymussel was initially present in 13 
of the 39 sites, indicated that the spinymussel was lost from 
significantly more sites (11 sites) than it colonized (3 sites) between 
the early 1990s and early 2000s (Wisniewski et al. 2005, p. 2). This 
test is imprecise because the failure to detect Altamaha spinymussels 
when present could result in both false colonizations (species missed 
during early surveys but detected in recent survey) and false 
extirpations (species detected during early survey but missed during 
recent survey). Thus, although the exact number of extirpations and 
colonizations between the two time periods may not be accurate, the 
much higher number of extirpations is suggestive of a decline over this 
time period.

Summary of Comments and Recommendations

    During the open comment periods for the proposed rule (75 FR 61664) 
and draft economic analysis, we requested that all interested parties 
submit comments or information concerning the proposed listing and 
designation of critical habitat for the Altamaha spinymussel. We 
contacted all appropriate State and Federal agencies (including the 
State of Georgia, from whom we directly requested comments), county 
governments, elected officials, scientific organizations, and other 
interested parties and invited them to comment. Articles concerning the 
proposed rule and inviting public comment were published by the 
Associated Press, The Brunswick News and the Florida Times Union. An 
article was also published by the Center for Biological Diversity.
    During the comment periods, we received a total of 79 comments. We 
received comments supporting the listing of the Altamaha spinymussel 
from the Georgia Department of Natural Resources-Wildlife Resources 
Division, the U.S. Army Corps of Engineers, three environmental groups, 
and 70 individuals including 9 letters and 65 postcards. We received 
two requests for an extension of the open comment period and notified 
requestors that the comment period would reopen for the Notice of 
Availability of the Draft Economic Analysis, published on May 12, 2011. 
We received no requests for, and therefore did not hold, a public 
hearing.

Peer Review

    In accordance with our peer review policy published in the Federal 
Register on July 1, 1994 (59 FR 34270), we requested the opinions of 
four knowledgeable individuals with expertise on freshwater mollusks, 
the Altamaha River Basin, and conservation biology principles. The 
purpose of peer 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.
    Peer reviewers stated that: (1) The proposal included a thorough 
and accurate review of the available scientific and commercial data on 
this mussel and its habitats; (2) the best available scientific data 
documented substantial declines in its abundance and distribution; and 
(3) the data supported the proposed listing as endangered with the 
designation of approximately 237.4 km (147.5 mi) of critical habitat. 
Two peer reviewers provided additional details and correction about the 
life history of the spinymussel, one of these reviewers also provided 
specific recommendations for the primary constituent elements (PCEs). 
The information provided by the reviewers has been incorporated into 
the appropriate sections of this final rule or is addressed in the 
comments below.
    We reviewed all comments received for substantive issues and new 
data regarding the spinymussel, its critical habitat, and the draft 
economic analysis. Written comments 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: Water quality standards set by the State of Georgia 
are based on water quality criteria established by the U.S. 
Environmental Protection Agency (EPA) for protection of aquatic life, 
not humans. Mussels are not currently represented in datasets used by 
EPA for derivation of water quality criteria. If adopted, the proposed 
criteria for ammonia will be the first to include mussel sensitivity 
data. Therefore, the statement that many of the standards may not be 
protective of mussels is accurate.
    Our response: We agree, and have incorporated this information into 
the Physical or Biological Features Section to reflect this comment. 
Also see Comment 4 below.
    (2) Comment: Dissolved Oxygen (DO) concentrations of 33.1 mg/L 
appear unusually high for a river segment with no dams. It seems 
appropriate to exclude this value as described by reporting the 10th 
and 90th percentiles for DO.
    Our response: After reviewing the data, we found three data points 
to be exceptionally high. All three were taken from the same timeframe 
with the same device, which suggests that the device may not have been 
calibrated correctly. These three data points have been thrown out, and 
the concentration range has been recalculated to 0.42-

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20.3 mg/l. The benefit of using the 10th and 90th percentiles is that 
it allows us to exclude the outliers from the data that may be due to 
device errors.
    (3) Comment: Populations of several fish species, particularly 
anadromous fishes (e.g. striped bass (Morone saxatilis), Atlantic and 
shortnose sturgeon (Acipenser oxyrinchus and A. brevirostrum), American 
shad (Alossa sapidissima), and other herrings), have declined 
substantially in recent decades. Host trials for spinymussels with 10 
species of fish from six families (Centrarchidae, Cyprinidae, 
Ictaluridae, Moronidae, Acipenseridae, Catostomidae) have been 
conducted. Unfortunately, none of these trials have produced juvenile 
spinymussels.
    Our response: We agree. One of the largest gaps in knowledge of 
this species is host fish information. Presence of suitable host fish 
in the basin is critical for survival of this species. Evaluation of 
habitat suitability for the spinymussel would be greatly enhanced with 
knowledge of the host fish occurrence and distribution; suitable 
habitat must also be present for the host fish(es). Though all 85 fish 
species native to the Altamaha Basin are still present, populations of 
several fish species have declined substantially compared to historic 
numbers. Host fish have been identified for other members of the genus 
Elliptio, and these species should provide a starting point for the 
spinymussel. Identification of suitable host fish is also critical for 
development of a propagation program. Laboratory culture of juveniles 
would allow for a potential population augmentation program and/or 
could be used to produce organisms for toxicity testing purposes. The 
Service has incorporated this information into the Physical or 
Biological Features Section to reflect this comment.
    (4) Comment: EPA has recently (2009) proposed to revise the chronic 
water quality value for ammonia (at pH 8 and 25 C) from 1.2 mg/L to 
0.26 mg/L. This value is calculated to protect 95% of aquatic species. 
Because ammonia toxicity data have not been generated for the Altamaha 
spinymussel it is prudent for the Service to consider a lower PCE value 
for ammonia such as 0.22 mg N/L as indicated in the proposal.
    Our response: We agree. We believe the value chosen for the PCE for 
ammonia is well supported, which is why it is being adopted by EPA 
(Newton et al. 2003, p. 2556 and Wang et al. 2007, pp. 2041-2043).
    (5) Comment: The commenter recommends adding criteria for copper, 
nickel, and pyrene. Copper toxicity to early life stages of unionids 
has been reported as low as 6.8 ug/L in a 96-hr test at a water 
hardness of 177 mg/L (Wang et al. 2007, p. 2043). Hardness buffers 
metal toxicity by reducing bioavailability of metal ions. Hardness 
values are much lower (20-40 mg/L) in the Altamaha, thus toxicity would 
be expected at even lower copper concentrations. Chronic criteria 
should be substantially lower than this acute value.
    Nickel toxicity has been reported for juvenile unionids at 190 ug/L 
in a 96-hr test with soft water (hardness <50 mg/L). Acute and chronic 
nickel criteria should be lower than 190 ug/L (no citation provided).
    Pyrene is a polycyclic aromatic hydrocarbon (PAH) that may be 
associated with pulp and paper mills among other industrial and urban 
sources. This PAH is toxic to unionid glochidia (24 h LC50) at 2.63 ug/
L in the presence of UV light (no citation provided). Chronic criteria 
for persistent, bioaccumulative compounds like PAHs should be 
substantially lower than acute toxicity values.
    Our response: The Service routinely consults with other federal 
agencies regarding the effects of their actions, and uses the best 
science available. Given the complex and unique conditions inherent in 
individual consultations, as well as at different times of year and 
areas of the river, we believe it would not be prudent to set standards 
for these compounds at this time because temperature, life stage, and 
other unknowns may have substantial impact on their toxicity (e.g., 
temperature and copper interaction). Where surrogate science was 
available and appropriate to establish general guidelines for water 
quality, it was applied in this manner. However, we do not have 
sufficient data to develop water quality criteria for copper, nickel, 
and pyrene at the level of specificity suggested by the commenter.

Comments From the State

    Section 4(i) of the Act states, ``the Secretary shall submit to the 
State agency a written justification for his failure to adopt 
regulations consistent with the agency's comments or petition.'' 
Comments received from the State regarding the proposal to designate 
critical habitat for the Altamaha spinymussel are addressed below.
    Because the comments of one peer reviewer (a State of Georgia 
employee) were adopted by the State, we are including them in our 
response to State comments. The State supports the designation of 
critical habitat for the occupied reaches of the Altamaha and Ocmulgee 
rivers as proposed, including the exclusion of the Altamaha River 
between U.S. Route 1 and the upper property boundary of Moody Forest 
Natural Area from proposed critical habitat. Georgia concurs with the 
Service that the designation of critical habitat in only the currently 
occupied reaches of the Altamaha and Ocmulgee Rivers would not 
adequately conserve the Altamaha spinymussel because this range is 
connected in a linear pattern that could be destroyed by a single event 
in the Ocmulgee, flowing downstream into the Altamaha. Therefore, the 
proposed designation of critical habitat in at least one additional 
tributary that historically harbored the Altamaha spinymussel is 
necessary to conserve the species.
    (6) Comment: One item that appears to be poorly supported is the 
considerable discussion found within the Summary of Factors Affecting 
the Species regarding contaminants in sediments of the Oconee River as 
primary threats. In the proposed rule the Service included extensive 
text on heavy metal toxicity due to kaolin mining/processing as a 
threat to unionids in the Oconee River Basin. The Service should also 
include extensive text regarding the presence and operations of Lake 
Sinclair.
    Our response: The effects of contaminants in sediment in the Oconee 
River and the entire Altamaha Basin are not well understood. However, 
it is clear that contaminants in sediment are a threat to mussel fauna 
in the Southeast and are, therefore, a potential threat to the 
spinymussel that must be evaluated in the Threats Assessment (Cope 
2008, pp. 452-459). Currently there are no data to describe the 
sensitivity of the spinymussel to environmental stressors such as 
temperature, dissolved oxygen, and contaminants, but tolerances to 
stressors can be inferred from other mussel species. The effects of 
these stressors on mussel fauna are often interconnected. Standardized 
ASTM (American Society for Testing and Materials) guidelines are 
currently available for toxicity tests with early life stages 
(glochidia and juveniles) of freshwater mussels. As a result, toxicity 
and thermal tolerance data are being generated for a growing number of 
unionid species. The Service considers contaminants in sediment a 
potential threat to the spinymussel throughout its range. The nearest 
reservoir is approximately 120 km (75 miles) from the historic range of 
the spinymussel and approximately 165 km (103 mi.) from occupied 
habitat, thus, the effects of hypolimnetic discharges are not 
considered a threat to the Altamaha spinymussel (also see Comment 7 and

[[Page 62932]]

Factor E. Other Natural and Man Manmade Factors Affecting Its Continued 
Existence).
    (7) Comment: The Oconee River downstream of Lake Sinclair was 
generalized as having sparse mussel populations. The proposal strongly 
suggests that this is a result of contaminants but does not allude to 
any effects due to the presence of a major dam and hydroelectric 
generation facility located at Lake Sinclair. Numerous published 
studies have recognized reservoirs and hydroelectric generation 
facilities as one of the leading reasons for declines and extinctions 
of unionids throughout North America.
    Our response: The Oconee River downstream of Lake Sinclair to U.S. 
Route 280 is poorly surveyed for mussels. Available surveys had 
described the mussel fauna as depauperate (EA Engineering 1995, pp. 1-
1, 3-1, 3-2, 4-2, and 4-3). Typically, habitats immediately downstream 
of dams are unsuitable for unionids due to the highly erosive nature of 
the substrates during channel forming events (e.g., spring floods), 
which scour substrates and deposit those benthic organisms occupying 
these habitats elsewhere. Additionally, eroding substrates are often 
deposited upon downstream habitats where unionids occur and thus impede 
their mobility and their ability to siphon or reproduce. Generally, the 
effects of reservoir operations on river channels are greatest closest 
to dams and gradually decline as rivers flow downstream. This effect is 
observed in the Oconee River, which has a deeply entrenched channel 
near Dublin, Georgia, upstream of the historic range of the 
spinymussel. Conversely, the Oconee River downstream of U.S. Route 280 
near Mt. Vernon (within the historic range of the spinymussel), has a 
wider, less entrenched channel with good floodplain connectivity, 
gentle bank slope, and riparian buffers. Mussel fauna diversity greatly 
increases in the lower portion of the Oconee, suggesting that the 
habitat is not degraded by dam operations. While the dam at Lake 
Sinclair certainly has a profound effect on the ecology of the Oconee 
River, it is 75 miles from the historic range of the spinymussel and, 
therefore, was not considered a threat (see Factor E. Other Natural and 
Man Manmade Factors Affecting Its Continued Existence).
    (8) Comment: The inclusion of the Lower Oconee River as critical 
habitat would more adequately conserve the Altamaha spinymussel than 
the inclusion of the Ohoopee River, as the Oconee River is a much 
larger watershed and would be less vulnerable to dewatering during 
periods of extreme drought, which will likely become more frequent in 
the future. The Oconee River from U.S. 280 in Mt. Vernon downstream to 
its confluence with the Altamaha River should be designated as an 
unoccupied stream reach proposed for critical habitat.
    Our response: We recognize that critical habitat designated at a 
particular point in time may not include all of the habitat areas that 
we may later determine are necessary for the recovery of the species. 
For these reasons, a critical habitat designation does not signal that 
habitat outside the designated critical habitat area is unimportant or 
may not be required for recovery of the species. The Service agrees 
that it is essential for the conservation of the species that one of 
the unoccupied tributaries to the Altamaha be included as critical 
habitat to avoid a linear distribution that might be vulnerable to a 
single catastrophic event. The Service has determined that only one of 
the unoccupied rivers is essential. In deciding which of the two rivers 
to include as critical habitat we looked at all historic records of 
spinymussel. In the Oconee River, the only record of spinymussels was 
from a single collection in 1968. The spinymussel has not been seen in 
the Oconee from any other locations or at any other time and is now 
considered extirpated from this river. Conversely, spinymussels have 
been found from multiple locations over several decades in the Ohoopee 
and were found as recently as 1997. Keferl referred to the Ohoopee as a 
possible refugia for the species endemic to the Altamaha, including the 
spinymussel (Keferl 1981, p. 15). Furthermore, the Oconee has many 
human-induced threats that are not well understood, including: Kaolin 
mining, agriculture, and municipal water treatment. The Ohoopee has 
fewer inputs of point source pollution within this basin; however, this 
river is impacted by municipal water treatment, drought, and, during 
low flows, vehicle traffic in the river bed. Drought is a natural event 
which mussel species have evolved to survive. Vehicle traffic in the 
river bed could be more easily managed than the potential threats to 
the Oconee, which may need extensive study to be understood. In 
determining which river would best serve to protect the spinymussel, 
the Service chose the Ohoopee because it was known to be inhabited by 
the spinymussel more recently, it was considered high-quality habitat 
(habitat that includes multiple PCEs), and manmade impacts should be 
easier to manage.
    (9) Comment: The continued declines of the Altamaha spinymussel are 
likely exacerbated by density-dependence in which too few individuals 
exist to adequately repopulate the basin at observable levels.
    Our response: We agree, and consider this to be the most serious 
threat faced by this mussel (for further explanation see Factor E. 
Other Natural and Man Manmade Factors Affecting Its Continued Existence 
and Determination).

Public Comments

    (10) Comment: In the proposed rule, the Service has not adequately 
considered the cost to other Federal agencies and how the listing might 
impact civil works programs such as dredging for commercial navigation 
or ecosystem restoration on the Altamaha, Oconee, and Ocmulgee Rivers.
    Our response: The Act and our regulations at 50 CFR 424.11(b) 
prohibit us from considering the possible economic impacts associated 
with listing a species. However, we do take into consideration economic 
impacts associated with designating critical habitat in accordance with 
section 4(b)(2) of the Act. Under section 7 of the Act, the U.S. Army 
Corps of Engineers (Corps) will need to consult with us for activities 
that may affect the Altamaha spinymussel or its critical habitat. We 
have broadly defined activities that may affect, 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. 
Our final economic analysis (Industrial Economics, Inc. 2011, pp. ES-2, 
ES-3, ES-4) found that there would be only marginal incremental 
administrative costs associated with this critical habitat designation. 
Incremental administrative costs are costs that would occur only as a 
result of the critical habitat designation, which are above and beyond 
costs associated with listing the species (i.e., baseline costs). The 
economic analysis projects approximately $37,100 of total incremental 
impacts (over the next 30 years (2011-2040)) using a seven percent 
discount rate), as the result of critical habitat designation for the 
Altamaha spinymussel.
    In order to estimate the cost of consultation the Service contacted 
the National Marine Fisheries Service (NMFS) to see how many 
consultations they conduct for the shortnose sturgeon

[[Page 62933]]

in the Altamaha River. NMFS biologists informed us that they average 
less than one formal consultation on the Altamaha annually and would 
estimate that they would conduct three formal consultations annually if 
critical habitat were designated for this species (Bolden 2011, pers. 
comm.). Because a listed species already occurs in these rivers, the 
Altamaha spinymussel listing and critical habitat designation would not 
be likely to prompt a large increase in the need for consultation or 
the associated costs to the Corps.
    (11) Comment: The proposal contains considerable speculation as to 
the possible causes for reduced populations of the Altamaha spinymussel 
but provides no substantive detail or analysis concerning the relative 
importance of factors contributing to the supposed primary stressors, 
sedimentation and contaminants.
    Our response: The Service has monitored the decline of the 
spinymussel since it first became a candidate species in 1984. Since 
that time the Service and the State have funded numerous efforts to 
develop a better understanding of the natural history of this species. 
Unfortunately, the low numbers of this species have made it difficult 
to study; therefore, we have analyzed the threats to this species using 
the best available science on surrogate species. The natural history of 
this species is likely very similar to other species in the family 
Unionidae, and it is reasonable to assume that similar threats will 
affect this species in a similar manner. Each threat is discussed in 
detail in the Summary of Factors Affecting the Species and is 
summarized in the Determination sections. A Threats Matrix detailing 
our best understanding of the relative importance has been developed 
and has been provided to the commenter. A copy of the Threats Matrix is 
on file and available upon request. We have also clarified the relative 
importance of specific threats, as needed, within the Threats Analysis 
of this rule.
    (12) Comment: The proposed rule misrepresents the (EPA's) Total 
Maximum Daily Load (TMDL) program and the impaired waters 
identification process and erroneously suggests that the current 
regulatory process is inadequate and will not afford protection to the 
spinymussel. The proposed rule implies or states directly that current 
regulatory water quality management tools are inadequate to protect 
existing spinymussel populations.
    Our response: The completion of and compliance with a TMDL removes 
a stream from the 303(d) list (list of impaired waterbodies). However, 
as stated, the stream is then placed on the 305(b) list of impaired 
streams with a completed TMDL whether or not water quality conditions 
improve. Furthermore, several waterbodies have been removed from the 
303(d) list upon completion of a TMDL, only to return to the 303(d) 
list due to additional violations. This indicates that while the TMDL 
program can improve water quality in streams, it does not prevent water 
quality violations from occurring, which could have a deleterious 
effect on the Altamaha spinymussel.
    (13) Comment: The proposed rule provides little or no justification 
for the water quality metrics (primary constituent elements, or PCEs) 
that are suggested as ``necessary for normal behavior, growth, and 
viability at all life stages.''
    Our response: In developing the parameters for the water quality 
PCE, we used the best available information to create specific 
guidelines (considering mussel life stage and interactions with 
variables such as temperature) including temperature, dissolved oxygen, 
ammonia, pH, and cadmium. How we derived these criteria is explained 
below. Conversely, there are many possible toxicity issues for which we 
do not believe there is sufficient information to develop water quality 
standards that would be protective of the spinymussel at this time (see 
also response to Comment 5).
Temperature PCE
    We believe that the maximum temperature and the maximum daily 
temperature fluctuation criteria identified in PCE 3 are supported by 
the best available data generated from direct temperature measurements 
of the Altamaha River, as well as comparisons to three temperature 
gauge stations on the Savannah River, which is similar in size, 
hydrology, and proximity (Wisniewski 2011, pers. comm.). Therefore, a 
maximum temperature of 32.6 [deg]C with no more than a 2 [deg]C daily 
fluctuation appears justified. See the Physical or Biological Features 
discussion to see how these were derived.
Dissolved Oxygen PCE
    Comments suggesting that dissolved oxygen in bottom layers of 
critical habitat may be lower than the PCE are not appropriate because 
spinymussels are found in the mainstem river in areas of moving water 
that does not stratify. Therefore, the water should be well-mixed and 
dissolved oxygen should be consistent throughout the water column.
Ammonia PCE
    For ammonia, 1.5 mg N/L is the criteria maximum concentration (CMC) 
and 0.22 mg N/L is the criteria continuous concentration (CCC). A 
review of mussel ammonia literature indicates that at least some 
juvenile mussels are sensitive to ammonia at concentrations as low as 
0.093 mg NH3/L in 10-d assays (Newton et al. 2003, p. 2556) and 0.37 mg 
N/L in 28-d tests (Wang et al. 2007, pp. 2041-2043). EPA did not 
include all mussel toxicity test data in derivation of the proposed 
criteria (2009) because some tests did not use `standardized' methods 
(Bringolf 2011, pers. comm.). The Service considered all available 
mussel ammonia toxicity data in deriving PCEs. The Service arrived at 
the ammonia PCE values as a compromise between the mussel toxicity 
literature and the proposed EPA criteria. There are no ammonia toxicity 
data available for spinymussel, therefore, we believe this to be the 
most valid approach for establishing a standard.
pH PCE
    The Service attempted to determine the `central range' of pH values 
in the Altamaha River by generating the 10th and 90th percentiles (the 
point at which 10% and 90%, respectively, of the observed values fell) 
of pH. Because the causes of the decline of the spinymussel remain 
unidentified, and no data are available regarding the optimal pH for 
this species, it is reasonable to designate a PCE for critical habitat 
that does not include the extremes of any water quality parameter 
(Bringolf 2011, pers. comm.). Critical habitat must be supportive of 
the species, and it is reasonable to assume that extremes of any 
parameter could be detrimental to this species. Critical habitat PCEs 
should incorporate the most stable habitats.
Cadmium PCE
    Mussel toxicity to cadmium (Cd) is reported to occur at 
concentrations as low as 16 [micro]g/L in 96-h tests with juveniles 
(Wang et al. 2010, pp. 2056-2057). The Cd criteria for Georgia are 1 
[micro]g/L (CMC) and 0.15 [micro]g/L (CCC). However, the commenter 
suggests that the Cd concentrations required to cause toxicity are 2000 
to 13,000 times greater than GA water quality criteria (1 ug/L). The Cd 
concentration that caused acute toxicity with juvenile mussels is only 
16 times higher than the Georgia Cd criteria. Therefore, it is not 
prudent to assume that Cd is not a significant contributor to decline 
in spinymussel populations. Early life stages are

[[Page 62934]]

generally more sensitive than adults; therefore, PCEs were established 
based on a survey of all published mussel early-life-stage toxicity 
data since 1992.
    Comment (14): Climate change models do not provide information that 
is appropriate for making management decisions regarding the Altamaha 
spinymussel.
    Our response: The Service agrees that it would not be appropriate 
to use climate change models to make management decisions regarding the 
Altamaha spinymussel. However, the Service acknowledges that climate 
change could alter the severity of storms and droughts, which could 
affect spinymussels in the future (See Factor E. Other Natural and Man 
Manmade Factors Affecting Its Continued Existence, also see the 
discussion under Critical Habitat, Background).
    Comment (15): The Service should consider that factors unrelated to 
habitat, such as invasive species, may be the most important limiting 
factor for the Altamaha spinymussel.
    Our response: While invasive species may be affecting the Altamaha 
spinymussel (either directly or indirectly), there is little, if any, 
information to support that invasive species are the most important 
limiting factor affecting the Altamaha spinymussel or other mussels 
native to the Altamaha or Atlantic Slope of Georgia. The flathead 
catfish (Pylodictis olivaris) was likely introduced into the Altamaha 
River during the 1970s or 1980s, and populations began to greatly 
increase during the 1990s. Flathead catfish may predate the host fish 
for the Altamaha spinymussel and other native unionids (see discussion 
under Factor E. Other Natural or Manmade Factors Affecting Its 
Continued Existence). However, despite the introduction of this 
piscivorous (fish eating) fish, most fish and mollusk species known 
from the Altamaha Basin as well as the remainder of the Atlantic Slope 
of Georgia, where the flathead catfish has been introduced, appear to 
be extant and relatively abundant. Similar trends occur in the nearby 
Flint River Basin where the flathead catfish has been introduced. 
Despite the introduction of this species and the highly altered nature 
of the Flint River, mussel species composition is similar to those 
experienced prior to the introduction of the flathead catfish 
(Wisniewski 2011, pers. comm.).
    The competition between the Asian clam (Corbicula fluminea) and 
native unionids has been examined, but results have been contradictory. 
Yeager et al. (2000, pp. 256-258) suggested that high densities of 
Asian clam may negatively influence unionid recruitment. However, 
Vaughn and Spooner (unpublished data, p. 5) indicated that Asian clam 
densities were generally lower when populations of native unionids were 
dense, but increased with declining populations of native unionids. 
Gardner et al. (1976, pp. 122-124) hypothesized that the decline in 
bivalve populations in the Altamaha River co-occurred with the invasion 
of Corbicula; they also admit that ``a combination of factors probably 
was responsible for the success of Corbicula and the decline of other 
bivalves in the Altamaha River.'' It is likely that the apparent 
declines in the densities of Altamaha spinymussels are a result of a 
variety of factors, some of which may be attributed to invasive 
species. The extent to which they are adversely affected by flathead 
catfish and Asian clam is currently unknown.
    Comment (16): The Service should recognize that suspended solids 
from biological wastewater treatment plants are often comprised largely 
of organic matter and that such solids would not be expected to 
contribute to sedimentation.
    Our response: The Service concurs with this comment; we have no 
information that suspended solids are a threat to the spinymussel at 
this time.
    Comment (17): Sediment issues in the southeastern United States are 
complicated by a legacy of poor agricultural practices during the 1800s 
and early 1900s, which raises questions about sources of sediment 
problems and the relative magnitudes of different sediment sources 
today. Silvicultural activities generally have only a small, short-
lived impact on water quality, especially when compared with other land 
uses.
    Our response: We agree that the primary source of sedimentation is 
legacy sediment and that silvicutural activities have a small and 
short-lived impact on water quality (see Factor A. The Present or 
Threatened Destruction, Modification, or Curtailment of Its Habitat or 
Range). Legacy sediment migrating through the floodplains of the 
Altamaha Basin is likely one of the most severe threats to the 
spinymussel. As an example, in Murder Creek, a tributary of the Oconee 
River, over 1.6 m (5.3 ft) of legacy sediment was observed (Jackson et 
al. 2005, p. 1). Much of the eroded sediment was believed to remain in 
valley storage or in transport as bedload in Georgia's Piedmont streams 
(Jackson et al. 2005, p. 3). Based upon estimates of inputs from 
various sources and exports via total suspended solids and bedload, 
sediment exports were greater than sediment inputs. It is assumed that 
the remainder of the sediment came from excavation and mobilization of 
stored valley sediments, principally through lateral migration of 
stream channels and bank erosion (Jackson et al. 2005, pg 10). Legacy 
sediment is an ongoing threat as it moves downstream covering suitable 
habitat.
    Comment (18): The Service should consider that implementation rates 
for forestry best management practices are high nationally and in 
Georgia, including the Altamaha River Basin.
    Our response: We agree that the rates of implementation for 
forestry BMPs are high and consider sediment from silvicultural 
activities to be a small and short-lived impact.
    Comment (19): When properly implemented, forestry BMPs protect 
water quality and habitat for the Altamaha spinymussel. BMPs are 
critical in mitigating water quality degradation from silviculture, and 
when appropriately implemented and maintained, are very effective in 
controlling nonpoint sources of pollution. Because of the overwhelming 
body of research related to BMPs and their effectiveness for protecting 
water quality and aquatic habitat, it is not surprising that the 
Service has recognized in previous regulatory proposals that BMPs are 
an important component of conservation strategies for freshwater 
mussels.
    Our Response: The Service agrees that BMPs are protective of water 
quality and mussel habitat, and that industrial forestry activities 
generally do a good job of implementing BMPs. However, some harvesting 
operations fail to use BMPs adequately, and localized impacts can and 
do occur.
    Comment (20): The Georgia Forestry Commission's BMP education and 
monitoring programs are effective at encouraging implementation of 
forestry BMPs and provide ``reasonable assurance'' that forestry BMPs 
are implemented effectively in Georgia.
    Our response: We generally agree with this comment, particularly on 
industrial forests. However, there are individual exceptions, with 
compliance reported by the Georgia Forestry Commission at around 95 
percent.
    Comment (21): Sustainable forestry certification programs require 
participants to meet or exceed forestry BMPs and help ensure high rates 
of BMP implementation.
    Our response: The Service agrees that the sustainable forestry 
program is one of the most effective programs to ensure BMPs are 
properly implemented.
    Comment (22): Preliminary sampling of direct tributaries in 
forested watersheds within the Altamaha River

[[Page 62935]]

Basin suggests that mussel communities are diverse and abundant. The 
role of lakes in supporting the mussel community within the basin is 
not known, but could be significant and should be explored further.
    Our response: We believe that floodplain lakes within the Altamaha 
Basin are of little importance to the Altamaha spinymussel as they do 
not have habitat to sustain the species. Dinkins (2007, p. 4) provides 
support for this by stating, ``species typically found in the river 
where the substrate has a dominant sand matrix and/or slight to 
moderate current during normal flow conditions (e.g., Elliptio spinosa, 
Lampsilis dolabraeformis) were not present in Cogden Lake.'' Cogden 
Lake is a floodplain lake in the Basin. The Altamaha spinymussel is 
typically found in association with protected areas around sand bars, 
in medium to coarse hard-packed sand, with rather swift current near 
gently sloping, soft banks with its distribution greatly restricted to 
these habitats (Meador 2009 p. 52, Sickel 1980, pp. 10-11; Wisniewski 
2008, p. 2). In general, floodplain lakes within the Altamaha River 
Basin exhibit habitats that are not conducive to the survival of the 
Altamaha spinymussel as these habitats typically have little or no flow 
and silty or muddy substrates.
    In conclusion, there is not sufficient evidence to support the 
existence of potential populations of the Altamaha spinymussel in these 
floodplain lakes or tributaries.
    Comment (23): The summary paragraph within Factor A, The present or 
Threatened Destruction, Modification, or Curtailment of Its Habitat or 
Range, is over-reaching and contains speculative language. Inferences 
that enforcement of laws and regulations may be subverted to economic 
interests and citing pending investigations by nongovernmental 
environmental groups (such as Riverkeepers) should not be relied on as 
the best scientific information available and are highly speculative 
regarding impacts to mussels and their habitat.
    Our response: The Service considers the best scientific and 
commercial information available when making listing decisions, and 
Riverkeepers have provided extensive and detailed field notes 
concerning water quality violations. Few of these notes were considered 
sufficient enough to include in this rule; however, the Altamaha 
Riverkeeper has successfully brought three cases to court (Altamaha 
Riverkeeper v. Amercord, Inc., No. CV 300-042 (S.D. Ga) (Order on 
Motion for Partial Summary Judgment, Mar. 15, 2001); Altamaha 
Riverkeeper v. City of Lumber City, CV-300-043 (S.D. Ga); Altamaha 
Riverkeepers v City of Cochran, 162 F. Supp. 2d 1368 (M.D. Ga. 2001)) 
regarding water quality standard violations (see Factor A discussion 
below for more detail). We consider these court findings to be relevant 
information related to enforcement of laws and regulations within the 
watershed.
    Comment (24): Two comments supported additional critical habitat 
including the entire historic range of the spinymussel, as well as, 
associated dry lands and wetlands.
    Our response: We believe the occupied and unoccupied areas we are 
designating as critical habitat adequately represent the geographical 
areas essential for the conservation of the species. See our response 
to Comment 8.
    Comment (25): Why was the area around Plant Hatch excluded from 
Critical Habitat designation?
    Our response: We did not include the section of the Altamaha River 
between US Route 1 and the upper property boundary of Moody Forest 
Natural Area from proposed critical habitat because it does not contain 
the physical or biological features essential to the conservation of 
the species. Dredging operations and thermal stress in the vicinity of 
Edwin I. Hatch Nuclear Plant have altered the habitat quality so that 
the PCEs are not present in this river reach. Habitat within this reach 
is generally unstable, consisting of coarse, mobile sand.

Summary of Factors Affecting the Species

    Section 4 of the Act and its implementing regulations (50 CFR part 
424) set forth the procedures for adding species to the Federal Lists 
of Endangered and Threatened Wildlife and Plants. A species may be 
determined to be an endangered or threatened species due to one or more 
of the five factors described in section 4(a)(1) of the Act. The five 
listing factors are: (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; and (E) other natural or manmade 
factors affecting its continued existence.

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Its Habitat or Range

    Bogan (1993, pp. 599-600 and 603-605) linked the decline and 
extinction of bivalves to a wide variety of threats including 
siltation, industrial pollution, municipal effluents, modification of 
stream channels, impoundments, pesticides, heavy metals, invasive 
species, and the loss of host fish. The Altamaha spinymussel lives 
within a large river drainage exposed to a variety of landscape uses. 
Habitat and water quality for the Altamaha spinymussel face degradation 
from a number of sources. Primary among these are threats from 
sedimentation and contaminants within the streams that the spinymussel 
inhabits.
    Sickel (1980, p. 12) characterized the habitat of the Altamaha 
spinymussel as coarse-to-fine-grain sandbars, and suggested that this 
may make the Altamaha spinymussel susceptible to adverse effects from 
sediment (siltation). Sediments deposited on the stable sandbars 
required by the Altamaha spinymussel could make sandbars unstable, 
result in suffocation, or simply change the texture of the substrate, 
making them unsuitable for the species. Sedimentation, including 
siltation from surface runoff, has been implicated as a factor in water 
quality impairment in the United States and has contributed to the 
decline of mussel populations in streams throughout the country (Ellis 
1936, pp. 39-41; Coon et al. 1977, p. 284; Marking and Bills 1979, pp. 
209-210; Wilber 1983, pp. 25-57; Dennis 1984, pp. 207-212; Aldridge et 
al. 1987, pp. 25-26; Schuster et al. 1989, p. 84; Wolcott and Neves 
1991, pp. 1-6; Houp 1993, p. 96; Bogan 1993, pp. 603-605; Waters 1995, 
pp. 53-77; Richter et al. 1997, p. 1084).
    Specific impacts on mussels from sediments include reduced feeding 
and respiratory efficiency, disrupted metabolic processes, reduced 
growth rates, increased substrata instability, and the physical 
smothering of mussels (Ellis 1936, pp. 39-41; Stansbery 1970, p. 10; 
Markings and Bills 1979, pp. 209-210; Kat 1982, p. 124; Aldridge et al. 
1987, pp. 25-26; Hartfield and Hartfield 1996, p. 375; Brim Box and 
Mossa 1999, pp. 99-102; TNC 2004, p. 4; Cope 2008, pp. 452-459). Many 
southeastern streams have increased turbidity levels due to siltation 
(van der Schalie 1938, p. 56). Since turbidity is a limiting factor 
that impedes the ability of sight-feeding fishes to forage (Burkhead 
and Jenkins 1991, pp. 324-325), turbidity within the Altamaha River 
Basin during the times that Altamaha spinymussels

[[Page 62936]]

attempt to reproduce may reduce the ability of the host fish to find 
glochidia, and may contribute to the decline of the spinymussel by 
reducing its efficiency at infecting the fish hosts necessary for 
reproduction. In addition, sediment can eliminate or reduce the 
recruitment of juvenile mussels (Brim Box and Mossa 1999, pp. 101-102), 
interfere with feeding activity (Dennis 1984, pp. 207-212), and act as 
a vector in delivering contaminants to streams (Salomons et al. 1987, 
p. 28).
    From 1700 to 1970, agricultural practices in the Southern Piedmont 
physiographic province resulted in extreme soil erosion, removing more 
than 17.8 cm (7 in.) of soil across the landscape (Trimble 1974, p. 1). 
The Ocmulgee, Oconee, and Ohoopee rivers all drain through the Piedmont 
and were directly affected by this erosion and resulting sedimentation. 
In 1938, van der Schalie (p. 56) reported the Altamaha River as being 
yellow in color, due to the large amount of suspended silt originating 
from intensive farming and road construction occurring in the 
headwaters. The sediment from these practices moved into stream 
channels and valleys, covering most of the original bottomlands 
(Trimble 1974, p. 26) and is now referred to as legacy sediment 
(Jackson et al. 2005, pg. 3). As a result, stream profiles have been 
dramatically altered with unstable sediment deposits being dissected 
and streams being incised with entrained sediment migrating downstream 
to be deposited in stream channels and floodplains (Trimble 1974, pp. 
116-121; Jackson et al. 2005, pg 1). The GDNR, Environmental Protection 
Division (EPD 2007, p. iii) reported to EPA that approximately 75 
percent of the average sediment load in the Altamaha River Basin 
resulted from row crops and that it contributed an average sediment 
load of 1 ton per acre per year. The EPD concluded that this sediment 
is probably a legacy of past land use. The mobilization of legacy 
sediments, principally through lateral migration of stream channels and 
bank erosion is an ongoing threat as it moves downstream covering 
suitable habitat (Jackson et al. 2005, p. 10). Large -scale sediment 
movement and deposition may result in increased embeddedness, which 
would generally decrease habitat quality (Bringolf 2011, pers. comm.). 
The degree to which rocks (gravel, cobble, and boulders) and snags are 
covered or sunken into the silt, sand, or mud of the stream bottom is a 
measure of embeddedness, and is a parameter evaluated in the riffles 
and runs of streams (also see Our Response to Comment 17). Although it 
is the historical, anthropogenic land use that created the legacy 
sediment, the volume of legacy sediment still migrating through the 
Altamaha River Basin is a significant threat to the spinymussel.
    Studies of the fish populations in the Altamaha River Basin were 
conducted in 2000 by the GDNR Wildlife Resources Division (WRD). The 
Index of Biotic Integrity (IBI) and modified Index of Well-Being (IWB) 
rate fish populations as being in Excellent, Good, Fair, Poor, or in 
Very Poor condition, and were applied by the WRD to identify impaired 
fish populations in the Altamaha River. Stream segments with fish 
populations rated as Poor or Very Poor were listed as Biota Impacted. A 
lack of fish habitat due to stream sedimentation was generally the 
cause of a low IBI score.
    Five Mile Creek (14.5 km/9 mi), Bullard Creek (12.8 km/8 mi), and 
Jacks Creek (14.5 km/9 mi) were rated as ``Very Poor'' and placed on 
the State of Georgia's 303(d) list of impaired waters due to a 
significant impact on fish (EPD 2007a, pp. 1-2). These three streams 
eventually feed into the mainstem of the Altamaha River via larger 
channels. As sediment moves through the basin, habitat is periodically 
buried. WRD recommends that there be no net increase in sediment 
delivered to the impaired stream segments so that these streams will 
recover over time (EPD 2007a, p. 26). Agriculture and roads were 
identified as the major sources of sediment with silviculture, mining 
sites, grazing, and urban development also contributing nonpoint 
sources of sediment (EPD 2007a, p. 9). Agriculture, including row 
crops, poultry farms, and pastures, constitute 15.5 percent of the land 
cover in the Piedmont and 32.7 percent of the land cover in the Coastal 
Plain (GDNR 2005, pp. 97, 132).
    In addition to agriculture, there are numerous sources of sediment 
within the Altamaha River Basin, including silviculture, unpaved roads, 
kaolin mines, and construction sites. A threat assessment conducted by 
TNC (2004, p. 9) listed sediment from urban, industrial, and nonpoint 
sources (NPSs) as a threat to the spinymussel. The EPD (2007, p. v) 
reported that, while historical row crop-based land use contributes the 
majority of sediment in the Altamaha River (75 percent), that among 
other sources, approximately 17.3 percent of the total sediment load is 
from roads; 4.3 percent from grasses and wetlands; 1.5 percent from 
urban lands; and 1.0 percent from quarries, strip mines, and gravel 
pits. In addition, estimates of the contribution from construction 
could not be obtained, but could represent a comparatively high 
sediment load on a per -acre basis (EPD 2007, p. v).
    Industrial forest management is practiced on approximately 8,000 
hectares (40,000 acres) or 33 percent of the floodplain of the Altamaha 
River (TNC 1997, p. 19). Typical forest management regimes in the 
Altamaha River Basin use timber harvest methods and conduct other 
activities that result in ground disturbances. These ground 
disturbances can result in transport of sediment to streams during and 
after precipitation events. In addition, forest management operations 
often require miles of unpaved roads to extract timber and to provide 
access for management activities. The majority of se