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Daily Rules, Proposed Rules, and Notices of the Federal Government

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.
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 athttp://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 (seeADDRESSESabove). 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; Copeet al.2008, p. 457).

Although the life history of the Altamaha spinymussel has not been studied, the life histories of other mussels in theElliptiogenus 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 genusElliptioare 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.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 (Johnsonet 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 (Cammacket 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 (Johnsonet 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 (m2) (5382-square feet (ft2)) site, and an additional 21 spinymussels were collected in a 400-m2(4306-ft2) (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.

Table 1—Decline in Range of the Altamaha Spinymussel River reach Historically
  • occupied
  • (linear km/mi)
  • Current habitat Percent of historical range lost
    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

    Using Georgia Department of Natural Resources (GDNR)'s database, which included many of the surveys mentioned above, Wisniewskiet 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 (Wisniewskiet 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 theFederal Registeron 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 0.42-20.3 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 oxyrinchusandA. 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 genusElliptio,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 mgN/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 (Newtonet al.2003, p. 2556 and Wanget 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 (Wanget 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 theSummary of Factors Affecting the Speciesregarding 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 andFactor 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 (seeApplication 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 sturgeonin 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 °C with no more than a 2 °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 (Newtonet al.2003, p. 2556) and 0.37 mg N/L in 28-d tests (Wanget 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 µg/L in 96-h tests with juveniles (Wanget al.2010, pp. 2056-2057). The Cd criteria for Georgia are 1 µg/L (CMC) and 0.15 µg/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 aregenerally 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. Yeageret 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. Gardneret al.(1976, pp. 122-124) hypothesized that the decline in bivalve populations in the Altamaha River co-occurred with the invasion ofCorbicula;they also admit that “a combination of factors probably was responsible for the success ofCorbiculaand 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 (Jacksonet 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 (Jacksonet 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 (Jacksonet 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 RiverBasin 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 Riverkeeperv.Amercord, Inc.,No. CV 300-042 (S.D. Ga) (Order on Motion for Partial Summary Judgment, Mar. 15, 2001);Altamaha Riverkeeperv.City of Lumber City,CV-300-043 (S.D. Ga);Altamaha RiverkeepersvCity 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; Coonet al.1977, p. 284; Marking and Bills 1979, pp. 209-210; Wilber 1983, pp. 25-57; Dennis 1984, pp. 207-212; Aldridgeet al.1987, pp. 25-26; Schusteret 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; Richteret 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; Aldridgeet 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 spinymusselsattempt 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 (Salomonset 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 (Jacksonet 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; Jacksonet 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 (Jacksonet 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 per