[Federal Register: June 6, 2006 (Volume 71, Number 108)]
[Proposed Rules]
[Page 32745-32796]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr06jn06-22]
[[Page 32745]]
-----------------------------------------------------------------------
Part III
Department of the Interior
-----------------------------------------------------------------------
Fish and Wildlife Service
-----------------------------------------------------------------------
50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Critical Habitat for
Five Endangered and Two Threatened Mussels in Four Northeast Gulf of
Mexico Drainages; Proposed Rule
[[Page 32746]]
-----------------------------------------------------------------------
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
RIN 1018-AU87
Endangered and Threatened Wildlife and Plants; Critical Habitat
for Five Endangered and Two Threatened Mussels in Four Northeast Gulf
of Mexico Drainages
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule.
-----------------------------------------------------------------------
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to
designate critical habitat for the endangered fat threeridge,
shinyrayed pocketbook, Gulf moccasinshell, Ochlockonee moccasinshell,
and oval pigtoe, and the threatened Chipola slabshell and purple
bankclimber (collectively referred to as the seven mussels), pursuant
to the Endangered Species Act of 1973, as amended (Act). We propose to
designate 11 units encompassing approximately 1,864 kilometers (1,158
miles) of river and stream channels as critical habitat. Proposed
critical habitat includes portions of the Econfina Creek drainage in
Florida, the Apalachicola--Chattahoochee--Flint River drainage in
Alabama, Florida, and Georgia, the Ochlockonee River drainage in
Florida and Georgia, and the Suwannee River drainage in Florida.
DATES: We will accept comments from all interested parties until August
7, 2006. We must receive requests for public hearings, in writing, at
the address shown in the ADDRESSES section by July 21, 2006.
ADDRESSES: If you wish to comment, you may submit your comments and
materials concerning this proposal by any one of the following methods:
1. You may submit written comments and information to the Field
Supervisor, U.S. Fish and Wildlife Service, 1601 Balboa Avenue, Panama
City, Florida 32405.
2. You may hand-deliver written comments to our office, at the
above address.
3. You may send comments by electronic mail (e-mail) to
FW4ESFRPanamaCity@FWS.gov. Please see the ``Public Comments Solicited''
section under SUPPLEMENTARY INFORMATION for file format and other
information about electronic filing.
4. You may fax your comments to 850-763-2177.
5. Federal eRulemaking Portal: http://www.regulations.gov. Follow
the instructions for submitting comments.
Comments and materials received, as well as supporting
documentation used in the preparation of this proposed rule, will be
available for public inspection, by appointment, during normal business
hours at U.S. Fish and Wildlife Service, 1601 Balboa Avenue, Panama
City, Florida 32405 (telephone 850-769-0552).
FOR FURTHER INFORMATION CONTACT: Jerry Ziewitz at the address above
(telephone 850-769-0552 ext. 223; facsimile 850-763-2177).
SUPPLEMENTARY INFORMATION:
Public Comments Solicited
We intend that any final action resulting from this proposal will
be as accurate and as effective as possible. Therefore, comments or
suggestions from the public, other concerned governmental agencies, the
scientific community, industry, or any other interested party
concerning this proposed rule are hereby solicited. We particularly
seek comments concerning:
(1) The reasons any habitat should or should not be determined to
be critical habitat as provided by section 4 of the Act (16 U.S.C. 1531
et seq.), including whether the benefit of designation will outweigh
any threats to the species due to designation;
(2) Specific information on the amount and distribution of habitat
for the seven mussels, including areas occupied by the seven mussels at
the time of listing and containing the features essential to the
conservation of the species, and areas not occupied at the time of
listing that are essential to the conservation of the species;
(3) Whether the middle section of the Flint River complex, between
the confluence of Gum Creek and the confluence of Auchumpkee/
Ulcohatchee Creek, has the Primary Constituent Elements for the
mussels, is occupied by the mussels, or is essential to the
conservation of the mussels;
(4) Land use designations and current or planned activities in the
subject areas and their possible impacts on proposed critical habitat;
(5) Any foreseeable economic, national security, or other potential
impacts resulting from the proposed designation and, in particular, any
impacts on small entities; and
(6) Whether our approach to designating critical habitat could be
improved or modified in any way to provide for greater public
participation and understanding, or to assist us in accommodating
public concerns and comments.
If you wish to comment, you may submit your comments and materials
concerning this proposal by any one of several methods (see ADDRESSES
section). Please submit e-mail comments to FW4ESFRPanamaCity@FWS.gov in
ASCII file format and avoid the use of special characters or any form
of encryption. Please also include ``Attn: 7 mussels--RIN 1018-AU87''
in your e-mail subject header, and your name and return address in the
body of your message. If you do not receive a confirmation from the
system that we have received your message, contact us directly by
calling our Panama City, Florida, Fish and Wildlife Office at phone
number 850-769-0552. Please note that the e-mail address
FW4ESFRPanamaCity@FWS.gov will be closed out at the termination of the
public comment period.
Our practice is to make comments, including names and home
addresses of respondents, available for public review during regular
business hours. Individual respondents may request that we withhold
their home addresses from the rulemaking record, which we will honor to
the extent allowable by law. There also may be circumstances in which
we would withhold from the rulemaking record a respondent's identity,
as allowable by law. If you wish us to withhold your name or address,
you must state this prominently at the beginning of your comment, but
you should be aware that the Service may be required to disclose your
name and address pursuant to the Freedom of Information Act. However,
we will not consider anonymous comments. We will make all submissions
from organizations or businesses, and from individuals identifying
themselves as representatives or officials of organizations or
businesses, available for public inspection in their entirety. Comments
and materials received will be available for public inspection, by
appointment, during normal business hours at the above address.
Role of Critical Habitat in Actual Practice of Administering and
Implementing the Act
Attention to and protection of habitat is paramount to successful
conservation actions. The role that designation of critical habitat
plays in protecting habitat of listed species, however, is often
misunderstood. There are significant limitations on the regulatory
effect of designation under Act section 7(a)(2). In brief, (1)
designation provides additional protection to habitat only where there
is a Federal nexus; (2) the protection is relevant only when, in the
[[Page 32747]]
absence of designation, destruction or adverse modification of the
critical habitat would in fact take place (in other words, other
statutory or regulatory protections, policies, or other factors
relevant to agency decision-making would not prevent the destruction or
adverse modification); and (3) designation of critical habitat triggers
the prohibition of destruction or adverse modification of that habitat,
but it does not require specific actions to restore or improve habitat.
Currently, only 475 species, or 36 percent of the 1,311 listed
species in the U.S. under the jurisdiction of the Service, have
designated critical habitat. We address the habitat needs of all 1,311
listed species through conservation mechanisms such as listing, section
7 consultations, the section 4 recovery planning process, the section 9
protective prohibitions of unauthorized take, section 6 funding to the
States, the section 10 incidental take permit process, and cooperative,
non-regulatory efforts with private landowners. The Service believes
that it is these measures that may make the difference between
extinction and survival for many species.
In considering exclusions of areas proposed for designation, we
evaluated the benefits of designation in light of Gifford Pinchot Task
Force v. United States Fish and Wildlife Service (378 F. 3d 1059 (9th
Cir 2004). In that case, the Ninth Circuit invalidated the Service's
regulation defining ``destruction or adverse modification of critical
habitat.'' In response, on December 9, 2004, the Director issued
guidance to be considered in making section 7 adverse modification
determinations. This proposed critical habitat designation does not use
the invalidated regulation in our consideration of the benefits of
including areas in this final designation. Rather, it relies on the
guidance issued by the Director in response to the Gifford Pinchot
decision (see ``Adverse Modification Standard'' discussion below). The
Service will carefully manage future consultations that analyze impacts
to designated critical habitat, particularly those that appear to be
resulting in an adverse modification determination. Such consultations
will be reviewed by the Regional Office prior to finalizing to ensure
that an adequate analysis has been conducted that is informed by the
Director's guidance.
On the other hand, to the extent that designation of critical
habitat provides protection, that protection can come at significant
social and economic cost. In addition, the mere administrative process
of designation of critical habitat is expensive, time-consuming, and
controversial. The current statutory framework of critical habitat,
combined with past judicial interpretations of the statute, make
critical habitat the subject of excessive litigation. As a result,
critical habitat designations are driven by litigation and courts
rather than biology, and made at a time and under a time frame that
limits our ability to obtain and evaluate the scientific and other
information required to make the designation most meaningful.
In light of these circumstances, the Service believes that
additional agency discretion would allow our focus to return to those
actions that provide the greatest benefit to the species most in need
of protection.
Procedural and Resource Difficulties in Designating Critical Habitat
We have been inundated with lawsuits for our failure to designate
critical habitat, and we face a growing number of lawsuits challenging
critical habitat determinations once they are made. These lawsuits have
subjected the Service to an ever-increasing series of court orders and
court-approved settlement agreements, compliance with which now
consumes nearly the entire listing program budget. This leaves the
Service with little ability to prioritize its activities to direct
scarce listing resources to the listing program actions with the most
biologically urgent species conservation needs.
The consequence of the critical habitat litigation activity is that
limited listing funds are used to defend active lawsuits, to respond to
Notices of Intent (NOIs) to sue relative to critical habitat, and to
comply with the growing number of adverse court orders. As a result,
listing petition responses, the Service's own proposals to list
critically imperiled species, and final listing determinations on
existing proposals are all significantly delayed.
The accelerated schedules of court-ordered designations have left
the Service with limited ability to provide for public participation or
to ensure a defect-free rulemaking process before making decisions on
listing and critical habitat proposals, due to the risks associated
with noncompliance with judicially imposed deadlines. This in turn
fosters a second round of litigation in which those who fear adverse
impacts from critical habitat designations challenge those
designations. The cycle of litigation appears endless and is expensive,
thus diverting resources from conservation actions that may provide
relatively more benefit to imperiled species.
The costs resulting from the designation include legal costs, the
cost of preparation and publication of the designation, the analysis of
the economic effects and the cost of requesting and responding to
public comment, and in some cases the costs of compliance with the
National Environmental Policy Act (NEPA; 42 U.S.C. 4371 et seq.). These
costs, which are not required for many other conservation actions,
directly reduce the funds available for direct and tangible
conservation actions.
Background
In this proposed rule, we intend to discuss only information about
the seven mussels that is directly relevant to the designation of
critical habitat. For more information about these seven mussels,
please refer to our final rule listing fat threeridge, shinyrayed
pocketbook, Gulf moccasinshell, Ochlockonee moccasinshell, and oval
pigtoe as endangered, and Chipola slabshell and purple bankclimber as
threatened published in the Federal Register on March 16, 1998 (63 FR
12664) and to our final recovery plan, which is available from the
Panama City, Florida Fish and Wildlife Office or online at http://www.fws.gov/endangered/recovery/Index.html#plans.
The purple
bankclimber (Elliptoideus sloatianus), Gulf moccasinshell (Medionidus
penicillatus), Ochlockonee moccasinshell (Medionidus simpsonianus),
oval pigtoe (Pleurobema pyriforme), shinyrayed pocketbook (Lampsilis
subangulata), Chipola slabshell (Elliptio chipolaensis), and fat
threeridge (Amblema neislerii) are variously distributed in four river
basins that flow into the northeast Gulf of Mexico: Econfina Creek,
Apalachicola River (a large basin generally labeled with the names of
its major tributaries, the Chattahoochee and Flint rivers, as the ACF
River Basin), Ochlockonee River, and Suwannee River.
The endangered fat threeridge is a medium-sized to large,
subquadrate, inflated, solid, and heavy-shelled mussel that reaches a
length of 10.2 centimeters (cm) (4.0 inches (in)). Large specimens are
so inflated that the width approximates the height. The umbos (bulges
near the hinge of the shell) are in the anterior quarter of the shell.
The dark brown to black shell is strongly sculptured with seven or
eight prominent horizontal parallel plications (ridges).
The endangered shinyrayed pocketbook is a medium-sized mussel that
reaches approximately 8.4 cm (3.3 in) in length. The shell is generally
elongated, with broad, somewhat inflated umbos and a rounded posterior
ridge. The shell is thin but solid. The
[[Page 32748]]
surface is smooth and shiny and ranges from straw-yellow to chestnut-
brown with a variable number of black to bright emerald-green rays,
which emanate from the umbo across the disk.
The shinyrayed pocketbook was listed as federally endangered under
the scientific name Lampsilis subangulata. The shinyrayed pocketbook
and three other Lampsilis species that are not federally listed are now
assigned to the newly recognized genus Hamiota (Roe and Hartfield 2005,
p. 1). Several characteristics, including glochidia packaging in a
superconglutinate, placement and shape of the marsupia, and glochidia
release through the excurrent siphon, support recognition of these
species as a distinct genus (Roe and Hartfield 2005, p. 1), and we plan
to implement the name change in a separate rule-making.
The endangered Gulf moccasinshell is a small mussel that reaches a
length of about 5.6 cm (2.2 in), is elongate-elliptical or rhomboidal
in outline, fairly inflated, and has relatively thin valves. The
ventral margin is nearly straight or slightly rounded. The posterior
ridge is rounded to slightly angled and intersects the end of the shell
at the base line. Females tend to have the posterior point above the
ventral margin and are more inflated than males.
The endangered Ochlockonee moccasinshell is small, generally under
5.6 cm (2.2 in) long. It is slightly elongate-elliptical in outline,
the posterior end obtusely rounded at the median line, and the ventral
margin broadly curved. The posterior ridge is moderately angular and
covered in its entire length with well-developed, irregular plications.
Sculpturing may also extend onto the disk below the ridge. The
periostracum (outside surface of the shell) is smooth. The color is
light brown to yellowish green, with dark green rays formed by a series
of connected chevrons or undulating lines across the length of the
shell.
The endangered oval pigtoe is a small-to-medium-sized mussel that
attains a length of about 6.1 cm (2.4 in). The shell is suboviform and
compressed. The periostracum is shiny smooth; yellowish, chestnut, or
dark brown; rayless; and with distinct growth lines. The posterior
slope is biangulate and forms a blunt point on the posterior margin.
The umbos are slightly elevated above the hingeline.
The endangered oval pigtoe is the only species among the seven
mussels of this proposed rule that occurs in all four Gulf of Mexico
river basins comprising their collective range: Econfina Creek, ACF,
Ochlockonee, and Suwannee. Morphological variation across this broad
range has led to the description of several nominal species since it
was originally described as Unio pyriformis (Lea 1857, p. 169-172).
Williams and Butler (1994, p. 111) recognized the form distributed in
the Ochlockonee and Suwannee River systems as the Florida pigtoe,
Pleurobema reclusum (Wright 1898, p. 111-112), consistent with Simpson
(1914, p. 1-1540). However, Turgeon et al. (1998, p. 36) recognized the
forms from all four basins as one species, P. pyriforme, which was the
taxonomic classification upon which we relied on for the 1998 final
rule listing this species as endangered. A recent study using molecular
genetic techniques compared tissue samples from three of the four
basins (Econfina Creek, ACF, and Suwannee), and concluded that the
Suwannee samples were distinctive and warranted specific status as P.
reclusum (Kandl et al. 2001, p. 10). We acknowledged these findings in
our 2003 final recovery plan, but have deferred any revisions to the
listing taxonomy pending review of an analysis that includes samples
from the Ochlockonee Basin as well. Peer review and publication of a
genetic analysis of samples from all four basins is expected sometime
in 2006 (J.D. Williams, USGS, pers. comm. 2005).
The threatened Chipola slabshell is a medium-sized species reaching
a length of about 8.4 cm (3.3 in). The shell is ovate to subelliptical,
somewhat inflated, and with the posterior ridge starting out rounded
but flattening to form a prominent biangulate margin. The periostracum
is smooth and chestnut-colored. Dark brown coloration may appear in the
umbo region, and the remaining surface may exhibit alternating light
and dark bands.
The threatened purple bankclimber is a large, heavy-shelled,
strongly sculptured mussel reaching lengths of 20.5 cm (8.0 in). A
well-developed posterior ridge extends from the umbo to the posterior
ventral margin of the shell. The posterior slope and the disk just
anterior to the posterior ridge are sculptured by several irregular
plications that vary greatly in development. The umbos are low,
extending just above the dorsal margin of the shell.
Life History
The seven mussels are all bivalve mollusks (clams) of the family
Unionidae. Unionid mussels generally live embedded in the bottom of
rivers, streams, and other bodies of water. They siphon water into
their shells and across four gills that are specialized for respiration
and food collection. Known food items include detritus (disintegrated
organic debris), diatoms, phytoplankton, zooplankton, and other
microorganisms (Coker et al. 1921, p. 88; Churchill and Lewis 1924, p.
462; Fuller 1974, p. 221). Adults are filter feeders and generally
orient themselves on or near the substrate surface to take food and
oxygen from the water above them (Kraemer 1979, p. 1085-1096).
Juveniles typically burrow completely beneath the substrate surface and
are pedal (foot) feeders (bringing food particles inside the shell for
ingestion that adhere to the foot while it is extended outside the
shell) until the structures for filter feeding are more fully developed
(Gatenby et al. 1996, p. 604; Yeager et al. 1994, p. 221).
Sexes in unionid mussels are usually separate. Males release sperm
into the water, which females take in through their siphons during
feeding and respiration. Eggs are fertilized and retained in the gills
of the female until the larvae (glochidia) fully develop. The glochidia
of most unionid species, including all seven species addressed in this
proposed rule, require a parasitic stage on the fins, gills, or skin of
a fish to transform into juvenile mussels (for species-specific
information, see ``Primary Constituent Elements--Fish Hosts''). Females
release glochidia either separately or in masses termed conglutinates,
depending on the mussel species. Exceptionally large conglutinates,
such as those of the shinyrayed pocketbook, are termed
superconglutinates. The duration of the parasitic stage varies by
mussel species, water temperature, and perhaps host fish species. When
the transformation is complete, juvenile mussels normally detach from
their fish host and sink to the stream bottom where, given suitable
conditions, they grow and mature to the adult form.
Distribution
The historical and current range of the seven mussels includes
portions of four river basins of the northeast Gulf of Mexico in
Alabama, Florida, and Georgia: Econfina Creek, ACF, Ochlockonee, and
Suwannee. Of these four basins, the ACF is the largest and the only one
that extends beyond the Coastal Plain physiographic province into the
Piedmont of Georgia and Alabama. Two or more of the seven mussels occur
in each of the four basins, except the Suwannee, in which only the oval
pigtoe is found. Because large reservoirs are unsuitable as habitat for
these mussels and the dams that impound them are barriers to the
movement of their host fishes, their
[[Page 32749]]
range within two of the basins (ACF and Ochlockonee) is divided into
two or more sub-basins that likely represent the maximum spatial extent
of potentially interbreeding populations. We estimate that the five
species listed as endangered are each extirpated from over half of
their historical ranges, and the two threatened species are extirpated
from about one-third of their historical ranges (USFWS 2003, p. 77).
Summary of Threats to Surviving Populations
The declining range and abundance of the seven mussels is due
mostly to changes in their riverine habitats resulting from dams,
dredging, mining, channelization, pollution, sedimentation, and water
withdrawals, and possibly also the introduction of nonnative species,
such as the Asian clam. Each of these threats affect one or more of the
physical and biological habitat features that we have identified as
essential to the conservation of the seven mussels, which we discuss in
detail under ``Primary Constituent Elements.''
More than 350 kilometers (km) (217 miles (mi)) of large and small
river habitat in the ACF and Ochlockonee basins within the current
range of the seven mussels is inundated by reservoirs. None of the
seven species are known to persist in impoundments, although a single
purple bankclimber was found in an impounded portion of the
Chattahoochee River (C. Stringfellow, Columbus State University, pers.
comm. 2000). Obligate riverine fishes, some of which may serve as hosts
for larvae of the seven mussels, are also eliminated by dams and
impoundments. Several populations of the seven species persist in
relatively small fragments of the four major river basins that are
isolated from other populations by impoundments or other large patches
of unsuitable habitat and by dams or other barriers to dispersal via
their fish hosts. Habitat fragmentation reduces the probability of
population persistence (Wilcox and Murphy 1985, p. 879-884), because
smaller, more isolated populations are less able to rebound from chance
adverse environmental, demographic, and genetic events (Shaffer 1981,
p. 131; Lande 1988, p. 1455).
A variety of activities may induce channel instability that
adversely affects habitat conditions for mussels. Because impoundments
block the natural downstream movement of sediment, channel degradation
is commonly observed in the tailwaters of dams (Williams and Wolman
1984, p. 14; Lignon et al. 1995, p. 187). The mean bed elevation of the
Apalachicola River downstream of Jim Woodruff Lock and Dam, which is
located at the confluence of the Chattahoochee and Flint rivers, has
degraded about 1.2 to 1.5 meters (m) (4 to 5 feet (ft)) since its
construction in the late 1950s (Light et al. 1998, p. 21). The main
channel of the river widened at a rate of about 0.45 m (1.5 ft) per
year, based on cross sections measured by the U.S. Army Corps of
Engineers (USACE) between 1980 and 2001 (USACE 2002, p. 1.1-8.3). The
Apalachicola River near the Chattahoochee-Flint confluence once
supported a particularly rich mussel bed, which included large numbers
of fat threeridge and purple bankclimber, but this bed had declined
substantially in diversity and numbers by the early 1970s (Heard 1975,
p. 1-31). Although the purple bankclimber persists, the fat threeridge
is now rare in the upper river (Brim Box and Williams 2000, p. 89).
Quantitative sampling using substrate sieves at two locations in the
upper river failed to detect juveniles of any unionid mussels
(Richardson and Yokley 1996, p. 137). The decline of the rich mussel
fauna of the Chattahoochee River was attributed partly to erosion from
intensive farming before the Civil War (van der Schalie 1938, p. 56;
Clench 1955, p. 96), although substantial erosion continued for several
more decades (Glenn 1911, p. 1-137; Trimble 1972, p. 454-457). The most
striking example of this erosion and resulting stream channel
instability is in the headwaters of Turner Creek, a Chattahoochee River
tributary in Stewart County, Georgia. The massive amount of sediment
that washed away was conveyed via Turner Creek over time to the
Chattahoochee River.
Channelization
Channelization (straightening a stream course by artificial cutoffs
and other means for flood control and navigation), dredging, snagging
(removal of large woody debris), in-stream gravel mining, and other
forms of direct stream channel modifications may induce channel
instability. A well-documented example of how direct modifications to a
stream induced substantial instability is the Homochitto River in
Mississippi, which incised 5 m (16.4 ft) and widened 450 percent
following channelization (Kesel and Yodis 1992, p. 99). Hartfield
(1993, p. 131-141) and Neves et al. (1997, p. 71-72) reviewed the
adverse effects of channel modifications on freshwater mollusks.
Dredging in the Apalachicola River to maintain navigability may be
contributing to observed channel instability in that system (letter
from G. Carmody, Service, to R. Keyser, USACE, dated August 8, 2003).
Channel instability induced by gravel mining has probably played a
significant role in extirpating the Gulf moccasinshell and oval pigtoe
from the Uchee Creek system (Howard 1997, p. 157), where a small
population of the shinyrayed pocketbook persists. A recent Service
stream habitat condition survey in the Ochlockonee Basin found evidence
of substantial channel instability (actively eroding banks) at only 9
of 181 sites surveyed, but classified over half of the sites (99) as
having a moderate risk of bank erosion (H. Blalock-Herod, Service,
pers. comm. 2006).
Sedimentation
Sedimentation is widely reported as a contributing factor in the
decline of stream mussel populations (Kunz 1898, p. 328; Ellis 1931, p.
5; 1936, p. 29; Imlay 1972, p. 76; Coon et al. 1977, p. 279; Marking
and Bills 1979, p. 204; Dennis 1985, p. 1-171; Aldridge et al. 1987, p.
17; Schuster et al. 1989, p. 84; Wolcott and Neves 1990, p. 74; Houp
1993, p. 93-97; Richter et al. 1997a, p. 1090; Brim Box 1999, p. 1-
108). Sedimentation is the process by which water detaches, transports,
and deposits soil materials on the substrates of streams, lakes, and
wetlands. In geomorphically stable stream reaches, sediment input is
balanced by sediment output, resulting in no net accumulation or loss
of sediment from the stream bed. Sediment input is increased by a
variety of human activities that are common in the range of the seven
mussels. Substantial sediment accumulation is one factor that may
induce channel instability. Lesser amounts may also adversely affect
substrate quality for mussels by altering its texture (usually by
increasing the percentage of fine materials) and by introducing harmful
pollutants.
Waters (1995, p. 173-176) reviewed the biological effects of
sediments in streams, and Mount (1995, p. 1-359) provided an overview
of the effects of various land uses on stream systems. Brim Box and
Mossa (1999, p. 99-117) reviewed the effects of sediments and land uses
specifically on mussels. They identified several activities that may
affect mussels through sedimentation, including logging, farming,
ranching, mining, and urbanization. Without adequate measures to
control erosion, these activities may deliver sediment to streams via
upland gullies, unpaved roads, road-side ditches, construction sites,
and other areas of soil disturbance. All of these activities are
widespread in the current range of the seven mussels.
Sediment samples from several ACF Basin streams contained elevated
[[Page 32750]]
concentrations of two heavy metals that are harmful to mussels: Copper
(found throughout the Piedmont) and cadmium (found in large Coastal
Plain tributaries of the Flint River) (Frick et al. 1998, p. 19).
Elevated concentrations of heavy metals (such as chromium and cadmium)
were measured in Asian clams and in sediment samples collected
downstream of two abandoned battery salvage operations on the Chipola
River (Winger et al. 1985, p. 141, 144). Farther downstream in the
Chipola River, the chromium concentrations found in the sediments of
Dead Lake (Winger et al. 1985, p. 141, 144) are toxic to mussels
(Havlik and Marking 1987, p. 1-20).
Impoundments
The operations of several dams and withdrawals of surface and
groundwater may alter flow regimes to a degree that adversely affects
mussels. Four portions of the range of the seven mussels are
immediately downstream of major mainstem dams. The Apalachicola River
is downstream of Jim Woodruff Lock and Dam (JWLD), which impounds Lake
Seminole, a large but shallow reservoir in the southwest corner of
Georgia with a storage capacity of about 86 million meters\3\ (70,000
acre-feet). Seminole is the downstream-most reservoir in a series of
much larger reservoirs on the Chattahoochee River with a cumulative
capacity of about 2.2 billion m\3\ (1.8 million ac-ft), which
represents about 11 percent of the average annual discharge from JWLD
(USACE 1998, p. 4.10, 4.48, 4.56). During extended periods without
substantial rainfall, however, as during 1999 to 2002, the flow of the
Apalachicola River may consist mostly of releases from storage in the
Chattahoochee reservoirs.
The Flint River is impounded by two mainstem reservoirs, Lake
Blackshear and Lake Worth. By impeding passage of host fishes, these
dams separate individuals of the shinyrayed pocketbook, Gulf
moccasinshell, oval pigtoe, and purple bankclimber into at least three
populations within the basin. Both dams are used for hydropower and are
licensed to operate generally in a run-of-river mode (releases
approximately equal reservoir inflow) (USACE 1998, p. 4.48, 4.56), but
short-term alterations of river flow may occur. A mainstem dam on the
Ochlockonee River creates Lake Talquin, which is licensed and operated
in a similar fashion. No dams have been constructed on Econfina Creek
or the Suwannee River and its major tributaries within the range of the
seven mussels.
Water Withdrawals
Water withdrawals for agricultural, municipal, and industrial use
may reduce stream flow and affect mussels. In the Dougherty Plain of
the lower Flint River Basin and upper Chipola River Basin, irrigated
agriculture is the largest consumptive water use (Marella et al. 1993,
p. 6, 13, 29, 42). Major crops in the region include cotton, peanuts,
corn, and soybeans, with the largest acreage irrigated by groundwater
using center pivot sprinkler systems. Due to the porous limestone
underlying this area, ground and surface waters are highly connected,
and the base flow of many streams is supported by the discharge of
springs (Torak et al. 1996, p. 1-106). This area is also the center of
the current range of several of the seven mussels. Approximately
172,125 hectares (ha) (425,000 acres (ac)) of cropland were irrigated
using center pivot systems in a 16-county area of Georgia in the lower
Flint River Basin, with an additional 30,375 ha (75,000 ac) irrigated
with surface waters (Litts et al. 2001, p. 23). Using models
representing surface water--groundwater dynamics in the lower Flint-
upper Chipola area, Albertson and Torak (2002, p. 22) found that 8 of
37 streams examined (7 of these 37 support listed mussels) were highly
sensitive to groundwater withdrawal and that during droughts these
streams may go dry.
Water supply for municipal and industrial needs are greatest in the
areas of greatest human population. Several large urban areas
(population greater than 100,000) are near or within the current range
of the seven mussels, including Dothan, Alabama; Panama City and
Tallahassee, Florida; and Albany, Atlanta, and Columbus, Georgia. The
largest of these is the Atlanta metro area, which extends into the
headwaters of the Flint River Basin. Population in the 16-county metro
area is forecast to increase from about 4 million people in 2000 to
about 8 million in 2030, when regional water planning authorities
predict water demand will equal available water supply from existing
and presently planned sources (Ashley 2005, p. 1). Water use will
likely increase along with increasing human population in each of the
four basins that support the seven mussels.
Water Quality
Water quality is reported as impaired or potentially impaired in
some portions of all four river basins within the current range of the
seven mussels, according to the water quality agencies of the three
States in their periodic assessments under Section 305(b) of the Clean
Water Act (CWA). Although water quality in the smallest of the four
basins, Econfina Creek, is generally good, mercury accumulation in fish
populations was cited as a potential impairment in Florida's most
recent basin status report (FDEP 2003a, p. 71). Barrios and Chelette
(2004, p. 7) described the hydrologic setting of Econfina Creek, which
strongly influences its water quality characteristics. Except during
periods of high rainfall, most of the flow in Econfina Creek derives
from the discharge of a series of at least 39 spring vents from the
Floridan Aquifer in the middle section of the creek. The ground water
contribution zone for these springs is large and encompasses a
significant portion of the creek's surface water basin. Water quality
in the Floridan Aquifer is vulnerable to land use activities in this
contribution zone.
Water quality in the largest of the four basins, the ACF, varies
considerably. Two small portions of the seven mussels' current range in
the ACF are within the State of Alabama: The entire Uchee Creek
watershed (a Chattahoochee River tributary) and the headwaters of the
Chipola River watershed (an Apalachicola River tributary). In the
latter, the Alabama Department of Environmental Management (2004, p. 7)
reports that Cypress Creek is impaired due to organic enrichment and
low dissolved oxygen (DO). We have no records of the seven mussels in
Cypress Creek; however, three of the species are known to occur within
a few miles downstream of its mouth. In the Florida portion of the ACF,
several stream segments that support one or more of the seven mussels
in the Chipola and Apalachicola watersheds are potentially impaired due
to excessive coliform bacteria, nutrients, un-ionized ammonia, or
turbidity (FDEP 2003b, p. 1-208). Mercury-based fish advisories apply
to one or more segments of both watersheds. The current range of the
seven mussels in the Flint River Basin includes 131 km (81 mi) that are
reported as not supporting or partially supporting designated uses due
to departures from Georgia's standards for DO or biological integrity,
or are under mercury-based fish consumption advisories (GDNR-EPD 2002,
p. 1/1-9/2). The streams listed include such Flint River tributaries as
Spring Creek and Kinchafoonee Creek, but not the mainstem. The
conditions in an additional 58 km (36 mi) of Flint River tributaries
occupied by the mussels violate the coliform bacteria standard.
[[Page 32751]]
Water quality is considered impaired in a majority of the mussels'
range in the Ochlockonee River Basin of Florida and Georgia. In both
States, the entire mainstem length of the river is impaired or
potentially impaired by excessive coliform bacteria or nutrients, low
DO, or is under mercury-based fish consumption advisories (FDEP 2003c,
p. 1-141; GDNR--EPD 2002, p. 1/1-9/2). A study of water and sediment
quality in the basin in relation to mussels found that sites with low
DO or elevated levels of lead, manganese, or ammonia no longer
supported their historical mussel assemblages, including the listed
species (Hemming et al. 2005, p. 2).
The range of the seven mussels in the Suwannee River Basin is
limited to one species (the oval pigtoe), to the Florida portion of the
basin, and to one watershed within that portion (the Santa Fe River
watershed). The oval pigtoe is currently known only from the New River
and a short segment of Santa Fe itself downstream of the mouth of the
New River. Most of the New River was listed as impaired due to
excessive coliform bacteria, excessive nutrients, and low DO in 1998,
and remains potentially impaired under Florida's current standards
(FDEP 2003d, p. 1-159).
Agricultural sources of contaminants in the ACF and Suwannee basins
include nutrient enrichment from poultry farms and livestock feedlots,
and pesticides and fertilizers from row crop agriculture (Couch et al.
1996, p. 1-58; Frick et al. 1998, p. 1-36; Berndt et al. 1998, p. 1-
32). A study by the U.S. Soil Conservation Service (1993, p. 26) (now
the Natural Resources Conservation Service) in the Flint River system
determined that between 72 and 75 percent of the nutrients entering
Lake Blackshear were derived from agricultural sources. Organochlorine
pesticides were found at levels in ACF Basin streams that often
exceeded chronic exposure criteria for the protection of aquatic life
(Buell and Couch 1995, p. 1; Frick et al. 1998, p. 11). Cotton is
raised in much of the region inhabited by these mussels. One of the
most important pesticides used in cotton farming, malathion, affects
mussels physiologically and may decrease respiration and feeding
ability (Kabeer et al. 1979, p. 71-73). Within the Suwannee River
basin, nutrient concentrations were greater in agricultural areas and
nitrates were found to exceed U.S. Environmental Protection Agency
(USEPA) drinking water standards in 20 percent of the surficial aquifer
groundwater samples (Berndt et al. 1998, p. 6). Mostly in urban areas,
pesticide concentrations were found to exceed criteria for protection
of aquatic life.
Many pollutants in the ACF Basin originate from urban stormwater
runoff, developmental activities, and municipal waste water facilities,
primarily upstream of the fall line (the line marking the relatively
abrupt elevation transition between the Piedmont physiographic province
and the coastal plain) (Frick et al. 1998, p. 1-36). Urban catchments
in Piedmont drainages have higher concentrations of nutrients, heavy
metals, pesticides, and organic compounds than do agricultural or
forested ones (Lenat and Crawford 1994, p. 185; Frick et al. 1998, p.
1-36), and at levels sufficient to affect fish health (Ostrander et al.
1995, p. 213). Couch et al. (1996, p. 50) counted 137 municipal
wastewater treatment facilities in the ACF Basin.
Host Fish
Collectively, eight species of fish are now considered probable
primary hosts for the larval life stage of four of the seven mussels:
Largemouth bass, spotted bass, bluegill, redear sunfish, weed shiner,
sailfin shiner, blackbanded darter, and brown darter (O'Brien and Brim
Box 1999, p. 136; O'Brien and Williams 2002, p. 150-152) (see ``PCEs--
Fish Hosts''). According to Lee et al. (1980, p. 1-854), the range of
each of these fishes encompasses the range of the respective mussel(s)
that successfully parasitized each species in laboratory tests, with
the possible exception of the sailfin shiner--oval pigtoe association.
The sailfin shiner does not occur far upstream of the fall line in the
ACF basin (B. Albanese, GA DNR Wildlife Division, pers. comm. 2006),
but the oval pigtoe does; therefore, at least one more fish likely
serves as a host for this species. None of the eight fishes is
protected under the Act or considered imperiled rangewide (Williams et
al. 1989, p. 2-20); however, Georgia recognizes the sailfin shiner as a
species of special concern (State rank ``S3''; rare or uncommon in
State). The four centrarchid fishes (the two basses, bluegill, and
redear sunfish) are each classified as game species by the three
States. Riverine fish populations in the southeast generally have been
adversely affected by a variety of the same habitat alterations that
have contributed to the decline of the region's mussel fauna (Etnier
1997, p. 91; Neves et al. 1997, p. 60; Warren et al. 1997, p. 106, 123-
125, 127, 131).
Non-Native Species
Asian Clam
The invasion of non-native aquatic species has contributed to the
decline of several North American mussel species (Neves et al. 1977, p.
72-75; Strayer 1999, p. 74). Some native mussels may go extinct due to
the continued spread of the zebra mussel (Dreissena polymorpha), a
species not yet established in the southeast (Ricciardi et al. 1998, p.
618). Another non-native bivalve, the Asian clam (Corbicula fluminea),
is well-established and almost ubiquitous in the range of the seven
mussels. Reports of Asian clam density vary considerably, from 9 per
square foot (Flint River, Sickel 1973, p. 11) to over 195 per square
foot (Santa Fe River, Bass and Hitt 1974, p. 16). In the New River
(Suwannee River drainage), Blalock and Herod (1999, p. 145-151) found
an overall density of 8 Asian clams per square foot in an area where
oval pigtoe density was 0.003 per square foot (Blalock-Herod 2000, p.
1-72). In one reach of the Apalachicola River immediately downstream of
Jim Woodruff Lock and Dam, the stream bed is almost entirely covered
with a layer of live and dead Asian clams several inches deep (J.
Ziewitz, personal observation). Several researchers have suggested that
the Asian clam competes with native mussels for food, nutrients, and
space (Heard 1977, p. 1-177; Kraemer 1979, p. 1094; Clarke 1986, p. 8),
particularly with juvenile unionids (Neves and Widlak 1987, p. 6).
Yeager et al. (2000, p. 257) determined that high densities of Asian
clams reduced survival and growth of newly metamorphosed juvenile
mussels. However, Asian clams are present at almost all locations where
the seven mussels for which we are proposing critical habitat in this
proposed rule are currently found, and the specific impact of this
species upon native mussels is largely unresolved (Leff et al. 1990, p.
415; Strayer 1999, p. 90).
Black Carp
The black carp (Mylopharyngodon piceus) is another introduced
species that may pose a threat to the seven mussels. Largest of the
Asiatic carp species, the black carp eats mollusks (snails and
mussels), and sterile fish are sometimes used in catfish aquaculture to
control snails that are the intermediate hosts of a catfish parasite
(Nico et al. 2001, p. 1-124). Escape of substantial numbers of the
sterile fish could significantly reduce numbers of native mussels where
the escape occurs, and the establishment of non-sterile black carp in
the wild could
[[Page 32752]]
conceivably extirpate entire mussel populations.
Previous Federal Actions
We listed the seven mussels under the Act on March 16, 1998 (63 FR
12664), and approved a final recovery plan for the seven species on
September 19, 2003 (68 FR 56647; October 1, 2003). In the final 1998
rule, we determined that designation of critical habitat was not
prudent. On March 15, 2004, the Center for Biological Diversity
(Center) filed a lawsuit in the U.S. District Court for the Northern
District of Georgia (Civil Action No. 1:04 CV-0729-GET) alleging that
we violated the Act by failing to designate critical habitat for the
seven mussels. We entered a settlement agreement with the Center on
August 31, 2004, which stipulates that the Service would submit for
publication in the Federal Register, on or before May 30, 2006, a new
prudency determination, and if designation was determined to be
prudent, a proposed rule designating critical habitat. This publication
is our new prudency determination and our proposed rule designating
critical habitat for the seven mussels.
Critical Habitat
Critical habitat is defined in section 3 of the Act as--(i) the
specific areas within the geographical area occupied by a species, at
the time it is listed in accordance with the Act, on which are found
those physical or biological features (I) essential to the conservation
of the species and (II) that may require special management
considerations or protection; and (ii) specific areas outside the
geographical area occupied by a species at the time it is listed, upon
a determination that such areas are essential for the conservation of
the species. Conservation, as defined under section 3 of the Act, means
to use and the use of all methods and procedures which are necessary to
bring any endangered species or threatened species to the point at
which the measures provided pursuant to the Act are no longer
necessary.
Critical habitat receives protection under section 7 of the Act
through the prohibition against destruction or adverse modification of
critical habitat with regard to actions carried out, funded, or
authorized by a Federal agency. Section 7 requires consultation on
Federal actions that are likely to result in the destruction or adverse
modification of critical habitat. The designation of critical habitat
does not affect land ownership or establish a refuge, wilderness,
reserve, preserve, or other conservation area. Such designation does
not allow government or public access to private lands.
To be included in a critical habitat designation, the habitat
within the area occupied by the species must first have features that
are essential to the conservation of the species. Critical habitat
designations identify, to the extent known using the best scientific
data available, habitat areas that provide essential life cycle needs
of the species (areas on which are found the primary constituent
elements, as defined at 50 CFR 424.12(b)).
Habitat occupied at the time of listing may be included in critical
habitat only if the essential features thereon may require special
management or protection. Thus, we do not include areas where existing
management is sufficient to conserve the species. Accordingly, when the
best available scientific data do not demonstrate that the conservation
needs of the species so require, we will not designate critical habitat
in areas outside the geographical area occupied by the species at the
time of listing. An area currently occupied by the species but was not
known to be occupied at the time of listing is likely, but not always,
essential to the conservation of the species and is typically included
in the critical habitat designation.
The Service's Policy on Information Standards Under the Endangered
Species Act, published in the Federal Register on July 1, 1994 (59 FR
34271), and Section 515 of the Treasury and General Government
Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)
and the associated Information Quality Guidelines issued by the
Service, provide criteria, establish procedures, and provide guidance
to ensure that decisions made by the Service represent the best
scientific data available. They require Service biologists to the
extent consistent with the Act and with the use of the best scientific
data available, to use primary and original sources of information as
the basis for recommendations to designate critical habitat. When
determining which areas are critical habitat, a primary source of
information is generally the listing package for the species.
Additional information sources include the recovery plan for the
species, articles in peer-reviewed journals, conservation plans
developed by States and counties, scientific status surveys and
studies, biological assessments, or other unpublished materials and
expert opinion or personal knowledge. All information is used in
accordance with the provisions of Section 515 of the Treasury and
General Government Appropriations Act for Fiscal Year 2001 (Pub. L.
106-554; H.R. 5658) and the associated Information Quality Guidelines
issued by the Service.
Section 4 of the Act requires that we designate critical habitat on
the basis of the best scientific data available. Habitat is often
dynamic, and species may move from one area to another over time.
Furthermore, we recognize that designation of critical habitat may not
include all of the habitat areas that may eventually be determined to
be necessary for the recovery of the species. For these reasons,
critical habitat designations do not signal that habitat outside the
designation is unimportant or may not be required for recovery.
Areas that support populations, but are outside the critical
habitat designation, will continue to be subject to conservation
actions implemented under section 7(a)(1) of the Act and to the
regulatory protections afforded by the section 7(a)(2) jeopardy
standard, as determined on the basis of the best available information
at the time of the action. Federally funded or permitted projects
affecting listed species outside their designated critical habitat
areas may still result in jeopardy findings in some cases. Similarly,
critical habitat designations made on the basis of the best available
information at the time of designation will not control the direction
and substance of future recovery plans, habitat conservation plans, or
other species conservation planning efforts, if new information
available to these planning efforts calls for a different outcome.
Prudency Determination
Section 4(a)(3) of the Act and its implementing regulations (50 CFR
424.12) require that, to the maximum extent prudent and determinable,
we designate critical habitat at the time a species is listed as
endangered or threatened. Our regulations at 50 CFR 424.12(a)(1) state
that the designation of critical habitat is not prudent when one or
both of the following situations exist: (1) The species is threatened
by taking or other activity and the identification of critical habitat
can be expected to increase the degree of threat to the species; or (2)
such designation of critical habitat would not be beneficial to the
species. In our March 16, 1998, final rule (63 FR 12664), we determined
that designating critical habitat was not prudent for the seven mussels
because it would result in no known benefit to the species and could
further pose a threat to them through publication of their site-
specific localities. However, several of our determinations that the
[[Page 32753]]
designation of critical habitat would not be prudent have been
overturned by court decisions (for example, Conservation Council for
Hawaii v. Babbitt (2 F. Supp. 2d 1280 [D. Hawaii 1998]); and Natural
Resources Defense Council v. U.S. Department of the Interior (113 F. 3d
1121, 1125 [9th Cir. 1997])).
We are already working with Federal and State agencies, private
individuals, and organizations in carrying out conservation activities
for the seven mussels, conducting surveys for additional occurrences,
and assessing habitat conditions. However, critical habitat designation
may provide additional information to individuals, local and State
governments, and other entities engaged in long-range planning, since
areas with features essential to the conservation of the species are
clearly delineated and, to the extent currently feasible, the primary
constituent elements of the habitat necessary to the survival of the
subspecies are specifically identified. Furthermore, although the low
numbers of these mussels make it unlikely that their populations could
withstand even moderate collecting pressure or vandalism, we do not
have specific evidence of taking, collection, vandalism, trade, or
unauthorized human disturbance.
Accordingly, we withdraw our previous determination that the
designation of critical habitat will not benefit the seven mussels and
will increase the degree of threat to the species. We determine that
the designation of critical habitat is prudent for these species. At
this time, we have sufficient information necessary to identify
specific areas that meet the definition of critical habitat and are,
therefore, proposing critical habitat for the seven mussels.
Methods
As required by section 4(b)(1) of the Act, we used the best
scientific and commercial data available in determining areas that
contain the physical and biological features essential to the
conservation of the seven mussels. We reviewed the available
information pertaining to their historical and current distributions,
life histories, host fishes, habitats, threats to mussels in general,
and threats to the seven mussels in particular. This information
includes our own site-specific species and habitat data; unpublished
survey reports; notes and communications with other qualified
biologists or experts; peer-reviewed scientific publications; the final
listing rule for the seven mussels; and our final recovery plan for the
seven mussels.
Our principal sources of information for identifying the specific
areas within the occupied range of the seven mussels on which are found
those features essential to their conservation were: the collective
database of locality records for the seven mussels, which is tabulated
in our 2003 final recovery plan and has been supplemented with surveys
completed since then, and the peer-reviewed scientific literature on
mussels' life history and habitat requirements. Our 1998 final listing
rule relied extensively upon data obtained in a rangewide status survey
of the seven mussels commissioned by the Service and conducted in 1991
and 1992 (cited as Butler (1993, p. 1-30) in the final listing). Most
of these data were taken in the ACF basin and have since been published
by Brim Box and Williams (2000, p. 3). Although mussel surveys have
been conducted since publication of the final listing rule at various
locations in the four river basins that encompass their known range,
the 1991-1992 status survey still provides a majority of the most
recent distributional records for these seven mussels. For purposes of
this proposed rule, the Service considers the most recent post-1990
survey data at a particular location as representing a species' current
presence or absence at that location, and we consider pre-1990 survey
data as representing historical distribution. We must extend the
definition of current distribution back to 1990 because mussels are
sedentary, long-lived animals, some species attaining maximum life
spans of 100 to 200 years (Neves and Moyer 1988, p. 185; Bauer 1992, p.
425; Mutvei et al. 1994, p. 163-186). It was rare in the 1991-1992
survey, and is still rare, to find juveniles of the seven mussels.
We relied on a variety of information sources for identifying
occupied areas in which the features essential to the conservation of
the seven mussels may require special management considerations or
protection, including land and water management plans of State and
regional government agencies, surveys of stream channel condition,
water quality assessments, and distributional information for host
fishes. We used the sources cited in our final recovery plan's summary
of known threats to the seven mussels to identify which essential
features may be most vulnerable in certain portions of the occupied
range.
Primary Constituent Elements
In accordance with section 3(5)(A)(i) of the Act and regulations at
50 CFR 424.12, we are required to base critical habitat determinations
on the best scientific and commercial data available and to consider
within areas occupied by the species at the time of listing those
physical and biological features that are essential to the conservation
of the species (PCEs), and that may require special management
considerations or protection. These include, but are not limited to:
Space for individual and population growth and for normal behavior;
food, water, air, light, minerals, or other nutritional or
physiological requirements; cover or shelter; sites for breeding,
reproduction, and rearing (or development) of offspring; and habitats
that are protected from disturbance or are representative of the
historic geographical and ecological distributions of a species.
The specific PCEs essential for the seven mussels are derived from
their biological needs as described in the Background section of this
proposal. Space for individual and population growth and normal
behavior, and sites for reproduction and development of offspring are
provided for the seven mussels on and within the streambed of stable
channels with a suitable substrate, which we have captured in the PCEs
regarding channel stability, substrate quality, and flow regime.
Because the seven mussels are dependent on fish to complete their
larval life stage, the PCE regarding fish hosts is a further
requirement for successful reproduction. Various nutritional and
physiological requirements are captured in the PCEs regarding flow
regime and water quality. These PCEs are explained in additional detail
below.
Channel Stability
Unstable channels do not favor mussels in part because adults and
juveniles are relatively sedentary animals. They are unable to move
quickly or across great distances from unsuitable to suitable
microhabitats on and in the stream bed. Several researchers have
reported direct adverse effects to mussels in aggrading (filling) and
degrading (scouring) channels (Vannote and Minshall 1982, p. 4106;
Kanehl and Lyons 1992, p. 7; Hartfield 1993, p. 133; Brim Box and Mossa
1999, p. 99-117). In degrading channels, mussels lose the substrate
sediment in which they anchor themselves against the current. Mussels
have been extirpated from streams experiencing a ``headcut'' (stream
bed degradation progressing in an upstream direction) and from
degrading reaches immediately downstream of dams. In aggrading channels
or in channels with
[[Page 32754]]
actively eroding stream banks, excess sediment fouls the gills of
mussels, which reduces feeding and respiratory efficiency, disrupts
metabolic processes, reduces growth rates, and physically smothers
mussels (Ellis 1936, p. 39; Stansbery and Stein 1971, p. 2178; Marking
and Bills 1979, p. 209-210; Kat 1982, p. 123; Vannote and Minshall
1982, p. 4105-4106; Aldridge et al. 1987, p. 18; Waters 1995, p. 173-
176; Brim Box 1999, p. 65).
In addition to the direct effects above, channel instability
indirectly affects mussels and their fish hosts in several ways.
Channels becoming wider and shallower via bank erosion develop more
extreme daily and seasonal temperature regimes, which affects DO levels
and many other temperature-regulated physical and biological processes.
Mussels in wider and shallower channels are likely more susceptible to
predation. Erosive channels lose the habitat complexity provided by
mature bankside vegetation, which reduces diversity and abundance of
fish species. Fewer fish means lower probability of mussel recruitment
(see ``Fish Hosts''). The many direct and indirect adverse effects of
channel instability on mussels and their fish hosts strongly suggest
that channel stability is a habitat feature essential to their
conservation.
Substrate Quality
Adult unionid mussels are generally found in localized patches
(beds) almost completely burrowed in the substrate with only the area
around their siphons exposed (Balfour and Smock 1995, p. 255-268). The
composition and abundance of adult mussels have been linked to bed
sediment distributions (Neves and Widlak 1987, p. 5; Leff et al. 1990,
p. 415). Substrate texture (particle size distribution) affects the
ability of mussels to burrow in the substrate and anchor themselves
against stream currents (Lewis and Riebel 1984, p. 2025). Texture and
other aspects of substrate composition, including bulk density (ratio
of mass to volume), porosity (ratio of void space to volume), and
sediment sorting may also influence mussel densities (Brim Box 1999, p.
1-86; Brim Box and Mossa 1999, p. 99-117). Although several studies
have reported adult habitat selection by substrate composition, most
species are found in a relatively broad range of substrate types
(Tevesz and McCall 1979, p. 114; Strayer 1981, p. 411; Hove and Neves
1994, p. 36; Strayer and Ralley 1993, p. 255), with few exceptions
(Stansbery 1966, p. 29-30). The seven mussels for which we are
proposing critical habitat in this proposed rule are found in a variety
of substrates, ranging from pockets of sand on bedrock to sandy mud,
but not in substrates composed of predominantly fine materials (more
than 50 percent silt or clay by dry weight) (Brim Box and Williams
2000, p. 1-143; Blalock-Herod 2000, p. 1-72).
Interstitial spaces (pores) in coarse stream substrates may become
clogged when fine sediment input to streams is excessive (Gordon et al.
1992, p. 1-444). Reduced pore space and pore flow rates reduce habitat
for juvenile mussels, which tend to burrow entirely beneath the
substrate surface, and for some adult mussels as well (Brim Box and
Mossa 1999, p. 99-117). At least some species of juvenile unionids feed
primarily on particles associated with sediments and pore water during
their early development (Yeager et al. 1994, p. 221). Fine sediments
act as vectors in delivering contaminants such as nutrients, heavy
metals, and pesticides to streams (Salomons et al. 1987, p. 13). Most
toxicity data for freshwater mussels is from tests with water-only
exposures, despite reports that contaminated sediments have contributed
to mussel declines (Newton 2003, p. 2543; Wilson et al. 1995, p. 213-
218).
Because the juveniles and adults of the seven mussels live in
relatively coarse and not predominantly fine-grained substrates, and
the introduction of fine-grained sediments and various pollutants is
likely detrimental to one or more of their life stages, we have
determined that substrate quality is a habitat feature essential to
their conservation.
Flow Regime
The species that are the subject of this proposed rule are all
riverine unionid mussels and are not found in natural or manmade ponds
and lakes. One known exception is a single large (and presumably old)
purple bankclimber found in Goat Rock Reservoir on the Chattahoochee
River by malacologist C. Stringfellow (Columbus State University) in
2000 (pers. comm. 2000). Otherwise, none of the seven mussels tolerate
impounded conditions or persist in intermittent streams (Brim Box and
Williams 2000, p. 1-141); therefore, continuously flowing water is a
habitat feature associated with all potentially viable populations.
Flowing water transports food items to the sedentary juvenile and adult
life stages and provides oxygen for mussel respiration at depths that
would be anoxic in a pond setting. At least three of the seven mussels
are known to attract host fishes visually by apparently disguising
their glochidia as potential prey items (O'Brien and Brim Box 1999, p.
135-136; O'Brien and Williams 2002, p. 154), and some of these
mechanisms appear to require flowing water to function effectively as
lures. For example, flowing water is required to suspend the several-
feet-long superconglutinate of the shinyrayed pocketbook in the water
column so that the glochidia packet at the end of it, which resembles a
small fish, is visible to fish (O'Brien and Brim Box 1999, p. 135,
138).
Quantifying the amount of flowing water that is essential to the
conservation of the seven mussels is complicated by the broad size
range of streams they inhabit, from small tributaries near watershed
headwaters to the Apalachicola River, which is the world's 82nd-largest
river by discharge (Leopold 1994, p. 101). These seven mussels are
often found near the toe of stable stream banks associated with roots
and other instream cover or structure. A flow sufficient to inundate
the stream bed from bank toe to bank toe with adequately oxygenated
water deep enough to deter terrestrial predators is several orders of
magnitude greater at a site on the lower Apalachicola River compared to
a site on a tributary stream in the upper Ochlockonee River.
Quantifying the amount of flowing water that is essential to the
conservation of the seven mussels is also complicated by their
dependency on various species of fishes to serve as hosts for their
glochidia. Mussel population viability is likely dependent on features
of the flow regime that influence fish host population density as well
as features that directly affect adult and juvenile mussel survival.
For example, the largemouth bass, which is a lab-verified host for the
fat threeridge and shinyrayed pocketbook (O'Brien and Brim Box 1999, p.
136; O'Brien and Williams 2002, p. 150), is known to utilize seasonally
inundated floodplain habitats for spawning and rearing (Kilgore and
Baker 1996, p. 291-294), habitats which do not support adult or
juvenile mussels because they are dry for several months of most years.
Year class strength of largemouth bass has been positively correlated
with flows in several river systems due to the additional habitat
available in high-flow years (Raibley et al. 1997, p. 852-853), and
fish host density is a factor in mussel recruitment (see ``Fish Hosts''
discussion below). Year class strength is abundance of a cohort (born
in a particular year) relative to other cohorts. A strong year class is
represented in much greater numbers than a weak year class, presumably
because the strong
[[Page 32755]]
year class experienced more favorable conditions for recruitment.
Riverine ecologists have recognized that variable flow creates
variable physical and chemical conditions that limit the distribution
and abundance of riverine species (Power et al. 1995, p. 166; Resh et
al. 1988, p. 443). Altering natural long-term patterns of flow changes
the structure, composition, and function of riverine communities (Bain
et al. 1988, p. 382-392; Hill et al. 1991, p. 198-210; Sparks 1995, p.
172-173; Scheidegger and Bain 1995, p. 134). Poff et al. (1997, p. 770)
and Richter et al. (1997b, p. 243) concluded that the accumulated
research on the relationship between hydrologic variability and
riverine ecological integrity overwhelmingly supported a ``natural flow
paradigm,'' that is, the patterns of variability in a river's natural
flow regime are critical in sustaining its ecological integrity.
Richter et al. (1996, p. 1165, 1997b, p. 236) proposed a set of
parameters collectively termed ``indicators of hydrologic alteration''
(IHA) for characterizing ecologically relevant features of a flow
regime.
The Service and USEPA adapted a subset of the IHA parameters as
instream flow guidelines for protecting riverine ecosystems under a
possible interstate water allocation formula between Alabama, Florida,
and Georgia for the ACF Basin (USFWS and USEPA 1999, p. 1). Although
the three States failed to agree upon an allocation formula and the ACF
Compact authorizing their negotiations expired, the Service has applied
the instream flow guidelines in consultations with Federal agencies on
actions affecting the species addressed in this proposed rule. The
Service-USEPA guidelines are definitions of measures of flow magnitude,
duration, frequency, and seasonality that may serve as thresholds for
``may affect'' determinations for proposed Federal actions that would
alter a flow regime (for example, water withdrawals and dam
operations). The thresholds are computed from long-term flow records
appropriate to the proposed action, such as daily flow records from a
stream gage in the action area. The Service-USEPA guidelines are
designed as a tool for site-specific analyses and such efforts as this
proposed rule.
Water Quality
The ranges of several standard physical and chemical water quality
parameters (such as temperature, DO, pH, conductivity) that define
suitable habitat conditions for the seven mussels have not been
specifically investigated. As sedentary animals, mussels must tolerate
the full range of these parameters to persist in that stream.
Quantifying water quality tolerances for the seven mussels is further
complicated by the dependency of mussels on fish hosts, which may
exhibit different tolerances.
Most mussels are considered sensitive to low DO levels and high
temperatures (Fuller 1974, p. 245). Johnson (2001, p. 8-11) monitored
water quality and mussel mortality during a drought year in the lower
Flint River Basin. Low DO levels, which occurred during low flow
periods, were associated with high weekly mussel mortality. Species-
specific mortality varied considerably. The shinyrayed pocketbook and
Gulf moccasinshell were among the species with the highest mortality
rates when exposed to DO concentrations less than 5 milligrams per
liter (mg/L). The oval pigtoe demonstrated moderate, but significantly
higher than average, mortality when DO was less than 5 mg/L.
Juvenile mussels may spend their first few years buried in the
sediments of the stream bed. Interstitial water (pore water) in
sediments is generally less oxygenated than flowing water in the stream
above (Sparks and Strayer 1998, p. 129). Sparks and Strayer (1998, p.
132) observed marked differences in behavior between juvenile Eastern
elliptio (Elliptio complanata), congener of the Chipola slabshell, that
were exposed to DO levels of 2 mg/L and 4 mg/L, and most juveniles of
this species that were exposed to 1.3 mg/L for a week died. In general,
juveniles are sensitive to low DO levels. Interstitial DO levels in
streams of the eastern United States are usually less than 4 mg/L in
the summer and may fall below 1 mg/L (Sparks and Strayer 1998, p. 132).
Water temperature affects the amount of oxygen that can be
dissolved in water and the toxicity of various pollutants. The toxic
effects of ammonia are more pronounced at higher temperatures and at
higher pH (Mummert et al. 2003, p. 2545, 2550; Newton 2003, p. 2543).
High temperatures or decreasing pH may increase the toxicity of metals
to unionids (Havlik and Marking 1987, p. 14). Watters and O'Dee (2000,
p. 136) suggested that the release of glochidia is regulated by water
temperature. In Texas, exceptionally warm temperatures appeared to
prompt early initiation of mussel reproductive activity, and cool
temperatures appeared to delay activity (Howells 2000, p. 40).
Temperature may affect immune system response in fish. Some fish
species that reject infections by mussel glochidia at higher
temperatures are infected at lower temperatures (Roberts and Barnhart
1999, p. 484).
Various contaminants in point- and non-point-source discharges can
degrade water and substrate quality and adversely affect mussel
populations (Horne and McIntosh 1979, p. 119-133; Neves and Zale 1982,
p. 53; McCann and Neves 1992, p. 77-81; Havlik and Marking 1987, p. 1-
20). Naimo (1995, p. 341) suggested that chronic, low-level
contamination of streams may explain the widespread decreases in mussel
density and diversity. Mussels appear to be among the organisms most
sensitive to heavy metals (Keller and Zam 1991, p. 539), several of
which are lethal at relatively low levels (Havlik and Marking 1987, p.
3). Cadmium appears to be the most toxic (Havlik and Marking 1987, p.
3), although copper, mercury, chromium, and zinc may also impair
physiological processes (Jacobson et al. 1993, p. 879; Naimo 1995, p.
353-355; Keller and Zam 1991, p. 539-546; Keller and Lydy 1997, p. 3).
Metals stored in mussel tissues indicate recent or current exposure
(Havlik and Marking 1987, p. 12), while concentrations in shell
material indicate past exposure (Imlay 1982, p. 7; Mutvei et al. 1994,
p. 163-186). Highly acidic pollutants such as metals may contribute to
mussel mortality by dissolving shells (Stansbery 1995, p. 2-3). Low
levels of some metals may inhibit glochidial attachment (Huebner and
Pynn[ouml]nen 1992, p. 2349). Mussel recruitment may be reduced in
habitats with low but chronic heavy metal and other toxicant inputs
(Yeager et al. 1994, p. 221; Naimo 1995, p. 341; Ahlstedt and
Tuberville 1997, p. 72-77).
Water pollutants associated with agricultural activity may
adversely affect mussels. Arsenic trioxide, which is used in the
poultry industry as a feed additive, is lethal to adult mussels at
concentrations of 16.0 parts per million (ppm), and ammonia is lethal
at concentrations of 5.0 ppm (Havlik and Marking 1987, p. 3, 13).
Ammonia is associated with animal feedlots, nitrogenous fertilizers,
and the effluents of older municipal wastewater treatment plants.
Ammonia causes a shift in glucose metabolism (Chetty and Indira 1995,
p. 84) and alters the utilization of lipids, phospholipids, and
cholesterol (Chetty and Indira 1994, p. 693). Stream ecosystems are
altered when nutrients are added at concentrations that cannot be
assimilated (Stansbery 1995, p. 2-3). Excessive nutrients promote the
growth of filamentous algae in streams, which may render substrates
unsuitable for mussels of all life stages and degrade water quality by
consuming oxygen during night-time respiration and
[[Page 32756]]
during decay to levels that mussels cannot tolerate. Several studies
have described adverse effects of pesticides on mussels (Fuller 1974,
p. 215-257; Havlik and Marking 1987, p. 13; Moulton et al. 1996, p.
131). Commonly used pesticides were cited as the likely cause of a
mussel die-off in a North Carolina stream (Fleming et al. 1995, p. 877-
879).
Gourdreau et al. (1993, p. 211-230) examined mussel populations
relative to the discharges of two municipal wastewater treatment plants
on the Clinch River in Tazewell County, Virginia. Mussels were absent
or present in low numbers immediately downstream of these discharges,
but occurred in greater diversity and abundance immediately upstream
and farther downstream. The investigators hypothesized that, in
addition to chemicals of known toxicity to glochidia, the bacteria and
protozoans associated with wastewater discharges may also adversely
affect mussel reproduction. Glochidia are vulnerable to attack by
bacteria and protozoans before and after they are released from the
adult female mussel (Fuller 1974, p. 219; Goudreau et al. 1993, p.
221).
Adults of some mussel species may tolerate short-term exposure to
various contaminants by closing their valves (Keller 1993, p. 701).
Juveniles and glochidia appear more sensitive than adults to heavy
metals (McCann and Neves, 1992, p. 77-81) and to ammonia (Goudreau et
al. 1993, p. 224). Ammonia is lethal to juveniles at concentrations as
low as 0.7 ppm total ammonia nitrogen, normalized to pH 8, and lethal
to glochidia at concentrations as low as 2.4 ppm (Augspurger et al.
2003, p. 2569-2575). In streams, ammonia may occur at highest
concentrations in substrate interstitial spaces where juvenile mussels
live and feed (Whiteman et al 1996, p. 794; Hickey and Martin 1999, p.
38; Augspurger et al. 2003, p. 2569-2575).
In general, we believe the numeric standards for pollutants and
water quality parameters (for example, heavy metals and DO) that are
adopted by the States under the Federal Clean Water Act (CWA) represent
levels that are essential to the conservation of the seven mussels.
However, some State standards may not adequately protect mussels, such
as the standard for ammonia (Augspurger et al. 2003, p. 2571; Newton et
al. 2003, p. 2559). USEPA and FWS and National Marine Fisheries Service
(the Services) agreed to a national consultation on the CWA Section
304(a) aquatic life criteria as part of a Memorandum of Agreement
regarding interagency coordination under the CWA and the Act (66 FR
11202, February 22, 2001). The criteria for some pollutants, such as
ammonia, are presently under review. Although the State standards
adopted consistent with the USEPA criteria generally represent levels
that are safe for the seven mussels, these standards are sometimes
violated in some streams within their current range. Rather than
specify the ranges of dozens of water quality parameters for the seven
mussels, it is more practical to deal with cases where the national
criteria are not protective of these and other listed species under the
national consultations with USEPA. For purposes of this proposed rule,
the evidence for the dependency of the seven mussels on good water
quality supports identifying water quality generally as a habitat
feature that is essential to their conservation.
Fish Hosts
Most unionid mussels, including the seven species, parasitize fish
during the larval life stage (see ``Background''), depending on fish
hosts not only for the physiological transformation from larval to
juvenile form (Isom and Hudson 1982, p. 147-151), but also for spatial
dispersal (Neves 1993, p. 4). The distribution and diversity of
unionids is strongly related to the distribution and diversity of fish
species (Watters 1992, p. 488; Haag and Warren 1998, p. 298). Bogan
(1993, p. 600) identified the dependency of mussels on fish hosts,
which are affected by exploitation and a variety of common habitat
alterations, as one of several contributing causes in the extinction of
several unionid species worldwide. Haag and Warren (1998, p. 303)
identified host fish availability and density as significant factors
influencing where certain mussel populations can persist.
Although female mussels may produce 75,000 to 3.5 million glochidia
(Surber 1912, p. 3-10; Coker et al. 1921, p. 144; Yeager and Neves
1986, p. 333), contact of the glochidia with a suitable host fish is a
low-probability event (Neves et al. 1997, p. 60). Contact is dependent
on many factors, including the timely presence of the host fish, the
feeding and respiratory behaviors of the fish (Dartnall and Walkey
1979, p. 36; Neves et al. 1985, p. 17-18), and for some species, the
behavior of the mussel when the fish is present (Davenport and Warmuth
1965, p. R77; Kraemer 1970, p. 225-282). Contact between glochidia and
host fish does not ensure successful larval development to the juvenile
form, because some fish species have natural immunity to glochidial
infestation and others acquire immunity following infestation (Watters
and O'Dee 1996, p. 387). Glochidia that contact a host with natural
immunity are rejected and die, usually within 11 days (Neves et al.
1985, p. 15, 17; Yeager and Neves 1986, p. 338; Waller and Mitchell
1989, p. 86). In the case of acquired immunity, glochidia experience
decreased transformation rates with subsequent infections of an
initially suitable host fish (Arey 1932, p. 372; Bauer and Vogel 1987,
p. 393; Luo 1993, p. 26). The number of exposures associated with
glochidial sloughing is variable (Watters and O'Dee 1996, p. 385, 387).
As few as 1 to as many as 25 fish species are known to serve as
suitable hosts for particular species of mussels (Fuller 1974, p. 238;
Trdan and Hoeh 1982, p. 386; Gordon and Layzer 1989, p. 1-98; Hoggarth
1992, p. 3). Some mussels are host-fish specialists that parasitize a
few fish species (Zale and Neves 1982, p. 2540; Yeager and Saylor 1995,
p. 4; Neves et al. 1985, p. 13, 17), and others are generalists that
parasitize a great variety of host fishes (Trdan and Hoeh 1982, p.
386). Generally, mussels that are known host-fish specialists tend to
release glochidia in conglutinates (multiple glochidia in a packet
versus a stream of single glochidia) or use various means of attracting
a fish host before releasing multiple glochidia (Watters 1997, p. 45).
Because fish that are not naturally immune to glochidial infection
develop some immunity after infection, securing a host fish is to some
degree a ``first come, first served'' situation. Some researchers have
hypothesized that mussels may compete for fish hosts (Watters 1997, p.
57; Trdan and Hoeh 1982, p. 384-385).
Watters (1997, p. 45-62) developed individual-based models of
mussel--fish interactions to simulate unionid reproductive strategies,
showing specialists tended to have lower population sizes and were less
sensitive to fluctuating host fish density than generalists, which
attained much higher population sizes when host fish density was high
and declined when host fishdensity declined.
Haag and Warren (1998, p. 297-306) examined patterns of fish and
mussel community composition in two north Alabama drainages. They found
that densities of host-generalist mussels and of host-specialist
mussels with elaborate host-attracting mechanisms were independent of
host-fish densities, and were present throughout the two drainages.
Densities of host-specialist mussels without elaborate host-attracting
mechanisms were positively correlated with host-fish densities and were
absent or rare near the drainages' headwaters.
[[Page 32757]]
Host-fish specificity has been examined in laboratory tests for
five of the seven mussels: the fat threeridge, Gulf moccasinshell, oval
pigtoe, purple bankclimber (O'Brien and Williams 2002, p. 151), and
shiny-rayed pocketbook (O'Brien and Brim Box 1999, 136). The fat
threeridge lacks mantle modifications or other morphological
specializations that would serve to attract host fishes and appears to
be a host-fish generalist that may infect fishes of at least three
different fish families. Glochidia transformed to juveniles under
laboratory conditions on five of seven fish species tested: Weed shiner
(Notropis texanus), bluegill (Lepomis macrochirus), redear sunfish (L.
microlophus), largemouth bass (Micropterus salmoides), and blackbanded
darter (Percina nigrofasciata) (O'Brien and Williams 2002, p. 152).
The elaborate superconglutinate of the shiny-rayed pocketbook (see
``Background'') suggests it is a host-fish specialist that targets
sight-feeding piscivorous fishes, such as bass. O'Brien and Brim Box
(1999, p. 136) confirmed that largemouth bass and spotted bass
(Micropterus punctulatus) are likely primary hosts (all fishes infected
produced juvenile mussels) among 11 species tested. Low transformation
rates were associated with fish such as the eastern mosquitofish
(Gambusia holbrooki) and bluegill.
The Gulf moccasinshell is probably a host-fish specialist that
primarily parasitizes darters. It visually lures host fish by
undulating its dark mantle flaps against swollen white gills (O'Brien
and Williams 2002, p. 154). O'Brien and Williams (2002, p. 152) lab-
tested eight fish species for suitability as hosts, finding that all
black-banded darters and brown darters (Etheostoma edwini) exposed to
infection transformed glochidia to juveniles. Other fishes, including
the eastern mosquitofish, also transformed glochidia, but at lower
percentage rates.
The extreme rarity of the Ochlockonee moccasinshell has precluded
any opportunities to explore its life history. We assume its
reproductive biology is similar to its congener, the Gulf
moccasinshell, which uses darters as host fish.
The oval pigtoe releases rigid white to pinkish conglutinates,
which passively drift in the current and may resemble the food
organisms of small-bodied fishes. O'Brien and Williams (2002, p. 152)
tested 11 fish species as hosts, finding that glochidia transformed on
the gills of fish such as the sailfin shiner (Pteronotropis
hypselopterus) and eastern mosquitofish. They considered only the
sailfin shiner as a primary host, as it was the only species upon which
the transformation rate exceeded 50 percent.
We are aware of no studies of the reproductive biology of the
Chipola slabshell. It is likely that the species expels glochidia in a
conglutinate, as do several other members of the genus Elliptio that
occur in the ACF Basin (Brim Box and Williams 2000, p. 34-47). Keller
and Ruessler (1997, p. 402-407) identified centrarchids (sunfishes) as
host fishes of other southeastern Elliptio.
O'Brien and Williams (2002, p. 153) observed in the laboratory that
purple bankclimber conglutinates readily disintegrated when they
contained mature glochidia, and these were easily suspended in the
water by the aerators in their holding tanks. They speculated that the
species may rely on stream currents to carry glochidia to host fish,
which is typical of host-fish generalist species. Of the 14 fish
species they tested as potential hosts, only a few species transformed
glochidia, including the eastern mosquitofish and blackbanded darter.
Only the mosquito fish was 100 percent effective (all fish tested
transformed glochidia), but it is an unlikely primary host fish. The
mosquito fish occupies backwater areas and stream margins with little
or no current (Lee et al. 1980, p. 1-854), while the bankclimber is
found mostly in the main channels of larger streams and rivers. The
primary host fishes of the purple bankclimber are still unknown.
Data that might suggest densities of the various primary host fish
species named above that are sufficient to support normal mussel
recruitment and dispersal rates are not available. Stochastic
simulations of fish'mussel interactions indicate that mussel
populations are extirpated if a threshold host fish density is not
exceeded (Watters 1997, p. 60). Further studies of fish and mussel
population dynamics are necessary to quantify species-specific
thresholds; however, we recognize that the presence of host fish is a
biological habitat feature essential to the conservation of the seven
mussels.
Primary Constituent Elements for Five Endangered and Two Threatened
Mussels
Based on our current knowledge of the life history, biology, and
ecology of the seven mussels, and of the habitat features necessary to
support their essential life history functions in areas occupied at the
time of listing, summarized above, we have determined that the PCEs
are:
(1) A geomorphically stable stream channel (a channel that
maintains its lateral dimensions, longitudinal profile, and spatial
pattern over time without an aggrading or degrading bed elevation);
(2) A predominantly sand, gravel, and/or cobble stream substrate;
(3) Permanently flowing water;
(4) Water quality (including temperature, turbidity, dissolved
oxygen, and chemical constituents) that meets or exceeds the current
aquatic life criteria established under the Clean Water Act (33 U.S.C.
1251-1387); and
(5) Fish hosts (such as largemouth bass, sailfin shiner, brown
darter) that support the larval life stages of the seven mussels.
Criteria Used To Identify Critical Habitat
We are proposing to designate as critical habitat areas that were
occupied at the time of listing by one or more of the seven mussels and
that contain one or more of the PCEs to support life history functions
essential to the conservation of the species. This section describes
how we identified those streams and delineated the upstream and
downstream boundaries of 11 proposed critical habitat units.
We began our analysis by examining the full extent of each species'
historical and current range. As discussed under ``Summary of Threats
to Surviving Populations'' above, the declining range and abundance of
the seven mussels is due mostly to changes in their riverine habitats
resulting from dams, dredging, mining, channelization, pollution,
sedimentation, and water withdrawals. The Econfina, ACF, Ochlockonee,
and Suwannee drainages contain about 54,000 km (33,500 mi) of perennial
streams (USGS 1:100,000 National Hydrography Data). From mussel survey
records, the historical range of the seven mussels collectively spanned
about 3,300 km (2,050 mi), or 6 percent, of the river and stream
channels in these drainages, but no one species accounts for more than
about 2,300 km (1,445 mi) of that total (USFWS 2003, p. 78-80). We
estimate that the five species listed as endangered are each extirpated
from over half of their historical range, and the two threatened
species are extirpated from about one-third of theirs, but none are
extirpated entirely from the four major drainages in which they each
occurred historically. All seven mussels were more widespread and more
abundant within each of the four drainages historically.
The largest single portion of the historical range lost to the
seven mussels is the mainstem of the Chattahoochee River. The
[[Page 32758]]
Chattahoochee comprised over 700 km (435 mi), or almost one-quarter, of
the 3,300-km (2,050-mi) collective historical range, and supported the
shinyrayed pocketbook, Gulf moccasinshell, oval pigtoe, and purple
bankclimber. It is now impounded by several major dams for much of its
length and no longer supports the listed mussels. With the exception of
a single live animal found in Goat Rock Reservoir in 2000, the purple
bankclimber appears extirpated from the entire Chattahoochee Basin, but
at least one of the other three species persist in three of its
tributaries: Uchee Creek, Sawhatchee Creek, and Kirkland Creek.
Elsewhere in the four major drainages, the pattern of extirpation is
more variable, with one or more of the seven species persisting in
portions of a drainage where others have disappeared. The collective
range of the seven species now spans about 1,900 km (1,180 mi) of river
and stream channels. Within this collective range, the species
presently occur in as little as 55 km (34 mi) (the Ochlockonee
moccasinshell) to as much as 785 km (488 mi) (the shinyrayed
pocketbook) (USFWS 2003, p. 78-80).
To identify the specific areas that were occupied at the time of
listing by each of the seven mussels and that contain one or more of
the PCEs, we used post-1990 mussel survey results. Because mussels are
sedentary and long-lived animals, occupancy is strong evidence that
some or all of the PCEs are present, except where it is apparent that
one or a few adult individuals remain at a location with little or no
possibility of reproducing due to substantial habitat alteration (such
as the single purple bankclimber found in Goat Rock Reservoir). It is
not feasible to survey all potential habitat for the seven species;
therefore, to delineate a species' occupied range in the larger stream
network, it is necessary to extrapolate from the available survey data.
Most of the tributary streams in the four basins that may support one
or more of the seven species have never been surveyed, and we do not
propose any unsurveyed streams as critical habitat. We used USGS
1:100,000 digital stream maps to delineate the probable upstream and
downstream limits to the seven species' distribution in streams
surveyed since 1990, according to the criteria listed below. These
limits form the boundaries of proposed critical habitat units as
explained below.
(a) The lateral boundaries of a unit are the ordinary high-water
marks on each bank of currently occupied streams. We recognize the
dynamic nature of riverine systems and that floodplains and riparian
areas are integral parts of those systems. Processes that occur and
habitat characteristics that are found outside the stream banks are
important in maintaining channel morphology, providing energy and
nutrients, and protecting the instream environment from pollutants and
excessive sediments. Similarly, floodplain and backwater habitats may
be important in the life cycle of fish that serve as hosts for mussel
larvae. Although factors affecting the PCEs may occur outside the
channel, the PCEs themselves occur within the channel.
(b) The upstream boundary of a unit in an occupied stream is the
first perennial tributary confluence or first permanent barrier to fish
passage (such as a dam) upstream of the upstream-most current
occurrence record. Many of the mussel survey sites are located near
watershed headwaters. In these areas, the confluence of a tributary
typically marks a significant change in the size of the stream and is a
logical and recognizable upstream boundary for habitat conditions that
are similar to the upstream-most occurrence record. Likewise, a dam or
other barrier to fish passage marks the upstream extent to which
mussels at the upstream-most occurrence may disperse via their fish
hosts. Therefore, proposed segments encapsulate habitat containing
essential features used by host fish and the seven mussels for
successful natural reproductive process. Habitat above these boundaries
does not contain features essential to the conservation of the species.
(c) The downstream boundary of a unit in an occupied stream is the
mouth of the stream, the upstream extent of tidal influence, or the
upstream extent of an impoundment, whichever comes first, downstream of
the downstream-most occurrence record. Many survey sites are located
near the mouths of streams, the upstream extent of impoundments, or the
upstream extent of tidal influence. Survey locations are typically at
road crossings, because that is where surveyors can most easily gain
access to the stream. These road crossings do not typically represent a
meaningful ecological boundary for longitudinal stream habitat
conditions. Mussels are dispersed via host fish, and because these host
fish traverse freely in the area between the upstream most occurrence
and any existing downstream restriction to fish passage, larvae drop
off their host fish at random points along the stream flow segments
traversed by fish. Further, the sperm of all seven species and the
conglutinates (glochidia packets) of some of the seven may be carried
downstream by currents and are viable for several hours to several days
unless they reach unsuitable habitat conditions, such as intolerable
salinity or still water, in which either would sink to the bottom and
be smothered in the sediments. Therefore, we are proposing stream
segments that have mussel point locations from the upstream limit as
defined in (b) above to the downstream location where the PCEs are no
longer present.
The application of these criteria resulted in the identification of
11 units occupied by one or more of the seven mussels and that contain
one or more of the PCEs as indicated by the presence and persistence of
one or more of the listed mussels (see ``Proposed Critical Habitat
Designation''). Based on fish distributional records (Lee et al. 1980,
p. 1-854) and our experience sampling fish in these drainages, these
areas also support shiners, darters, and other fishes that have been
identified as hosts or potential hosts for one or more of the seven
mussels. Further, on the basis of a review of the information
available, we have determined that areas not currently known to be
occupied by the seven mussels do not appear to be essential to their
conservation. As such, we have not included any areas not known to be
occupied by these mussel species in this proposed designation.
When determining the boundaries of proposed critical habitat for
the seven mussels, we made every effort to avoid manmade structures
existing on the effective date of this rule and not containing one or
more of the primary constituent elements, such as buildings and roads.
Any such structures inadvertently left inside the critical habitat
boundaries have been excluded by the text in this proposed rule and are
not proposed for designation.
Special Management Considerations or Protection
When designating critical habitat, we assess whether the areas
determined to be occupied at the time of listing and containing the
PCEs may require special management considerations or protections.
Activities in or adjacent to each of the critical habitat units
described in this proposed rule may affect one or more of the PCEs that
are found in the unit. These activities include, but are not limited
to, those listed in the Adverse Modification Standard section as
activities that may destroy or adversely modify critical habitat. We
find that the features essential to each of the seven mussel species
contained within the areas proposed for designation may require special
management considerations or protections due to known or probable
[[Page 32759]]
threats from these activities. We summarize here the nature of the
threats and the resulting conservation needs for both the mussels and
their host fish across the range of the seven mussels.
Sedimentation is an almost ubiquitous threat in the range of the
seven mussels. A wide variety of activities, such as livestock grazing,
road and bridge construction, clear-cut logging, and off-road vehicle
use, that are common in all 11 units may increase erosion rates, either
in the banks of the stream channel itself or elsewhere in the
watershed, and cause the accumulation of fine sediments on the stream
bed. Management considerations to deal with this threat include
protecting streams from sedimentation through application of
agricultural and forestry best management practices, avoiding soil- and
vegetation-disturbing activity in the riparian zone, restoring unstable
stream channels and other erosive areas, and other practices that
prevent or reduce erosion.
Urbanization, road and bridge construction, and other large-scale
alterations of land cover that substantially alter the runoff
characteristics of the watershed may threaten channel stability in
units near the major urban areas of Dothan, Alabama (unit 2); Panama
City and Tallahassee, Florida (units 1 and 10); Albany, Atlanta, and
Columbus, Georgia (units 3, 5, 6, and 7); and other cities. Management
considerations to deal with the threat of channel instability include
avoiding soil- and vegetation-disturbing activity in the riparian zone,
limiting impervious surface area, and other urban storm water runoff
control methods. Sand and gravel mining (unit 3), dredging and
channelization (unit 8), and dam construction (unit 5) may also affect
channel stability.
The construction and operation of dams, water withdrawals, and
water diversions may alter features of the flow regime important to the
mussels and their host fishes. This threat is present to some degree in
all 11 proposed units, but is greatest in units 5, 6, 7, 8, and 10,
which are downstream of the major mainstem dams or in areas of
relatively high municipal, industrial, or agricultural water use.
Measures to deal with this threat include water conservation and
operational strategies that manage water storage capacity and water
demands in combination to minimize departures from the natural flow
regime.
Water pollution, especially from non-point (dispersed release)
sources, is another almost ubiquitous threat in all 11 units. Water
quality is reported as impaired or potentially impaired in some
portions of all four river basins within the current range of the seven
mussels, according to the water quality agencies of the three States in
their periodic assessments under Section 305(b) of the Clean Water Act
(CWA) (see ``Summary of Threats to Surviving Populations''). Streams
that receive a high proportion of their flow from the discharge of
springs are vulnerable to nutrient enrichment from fertilizers and to
other pollutants applied in the recharge areas of those springs (units
1, 2, and 7), which may extend far from the streams themselves.
Management considerations to deal with the threat of pollution include
applying agricultural and forestry best management practices,
preserving native vegetation in riparian zones, maintaining septic
systems, and taking other measures to minimize pollutant-laden runoff
to streams.
Proposed Critical Habitat Designation
We are proposing 11 groups of river and stream segments (units) as
critical habitat for the seven mussels. The river and stream segments
comprising each unit are contiguous to allow for the movement of fish
hosts dispersing the larval life stages of the seven mussels within the
unit. Barriers to the movement of fish hosts (dams and salt water)
separate the units from each other. The critical habitat units
described below constitute our best assessment at this time of areas
that were occupied by one or more of the seven mussels at the time of
listing (1998) and which contain the physical and biological features
essential to the each of the mussel species. Each unit is designated
only for those species that currently occupy it. Each unit contains one
or more of the PCEs, and may require special management considerations
or protection to address the threats noted above. The 11 units, and the
States in which they occur, are: (1) Econfina Creek (FL), (2) Chipola
River (AL, FL), (3) Uchee Creek (AL), (4) Sawhatchee Creek and Kirkland
Creek (GA), (5) Upper Flint River (GA), (6) Middle Flint River (GA),
(7) Lower Flint River (GA), (8) Apalachicola River (FL), (9) Upper
Ochlockonee River (FL, GA), (10) Lower Ochlockonee River (FL), and (11)
Santa Fe River and New River (FL). Collectively, the total length of
the river and stream segments of all of the areas (units) proposed is
approximately 1,864 km (1,158 mi). Table 1 shows the approximate length
of rivers and streams proposed as occupied critical habitat for each of
the seven mussels in the 11 units.
------------------------------------------------------------------------
Currently occupied
Species, critical habitat unit, and -------------------------------
state(s) Kilometers Miles
------------------------------------------------------------------------
Fat threeridge
2. Chipola River, AL, FL................ 190.0 118.1
8. Apalachicola River, FL............... 155.4 96.6
-------------------------------
Total............................... 345.4 214.7
------------------------------------------------------------------------
Shinyrayed pocketbook
2. Chipola River, AL, FL................ 190.0 118.1
3. Uchee Creek, AL...................... 34.2 21.2
4. Sawhatchee Creek and Kirkland Creek, 37.8 23.5
GA.....................................
5. Upper Flint River, GA................ 380.4 236.4
6. Middle Flint River, GA............... 302.3 187.8
7. Lower Flint River, GA................ 396.7 246.5
9. Upper Ochlockonee River, FL, GA...... 177.3 110.2
-------------------------------
Total............................... 1518.7 943.7
------------------------------------------------------------------------
Gulf moccasinshell
1. Econfina Creek, FL................... 31.4 19.5
2. Chipola River, AL, FL................ 190.0 118.1
[[Page 32760]]
4. Sawhatchee Creek and Kirkland Creek, 37.8 23.5
GA.....................................
5. Upper Flint River, GA................ 380.4 236.4
6. Middle Flint River, GA............... 302.3 187.8
7. Lower Flint River, GA................ 396.7 246.5
-------------------------------
Total............................... 1338.3 831.8
------------------------------------------------------------------------
Ochlockonee moccasinshell
9. Upper Ochlockonee River, FL, GA...... 177.3 110.2
-------------------------------
Total............................... 177.3 110.2
------------------------------------------------------------------------
Oval pigtoe
1. Econfina Creek, FL................... 31.4 19.5
2. Chipola River, AL, FL................ 190.0 118.1
4. Sawhatchee Creek and Kirkland Creek, 37.8 23.5
GA.....................................
5. Upper Flint River, GA................ 380.4 236.4
6. Middle Flint River, GA............... 302.3 187.8
7. Lower Flint River, GA................ 396.7 246.5
9. Upper Ochlockonee River, FL, GA...... 177.3 110.2
11. Santa Fe and New Rivers, FL......... 83.1 51.6
-------------------------------
Total............................... 1598.7 993.6
------------------------------------------------------------------------
Chipola slabshell
2. Chipola River, AL, FL................ 190.0 118.1
-------------------------------
Total............................... 190.0 118.1
------------------------------------------------------------------------
Purple bankclimber
5. Upper Flint River, GA................ 380.4 236.4
6. Middle Flint River, GA............... 302.3 187.8
7. Lower Flint River, GA................ 396.7 246.5
8. Apalachicola River, FL............... 155.4 96.6
9. Upper Ochlockonee River, FL, GA...... 177.3 110.2
10. Lower Ochlockonee River, FL......... 75.4 46.9
-------------------------------
Total............................... 1487.2 924.4
¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤¤
Total Proposed for All 11 Units 1864.0 1158.3
(All Species)..................
------------------------------------------------------------------------
Brief descriptions of each unit follow, listing the rivers and
streams included, the upstream and downstream extent of the unit in
those rivers and streams, and which of the seven mussels were present
at the time of listing. Each critical habitat unit includes the
channels of the rivers and streams listed between the ordinary high
water mark on each bank, which is defined in 33 CFR 329.11 as ``the
line on the shore established by the fluctuations of water and
indicated by physical characteristics such as a clear, natural line
impressed on the bank; shelving; changes in the character of soil;
destruction of terrestrial vegetation; the presence of litter and
debris; or other appropriate means that consider the characteristics of
the surrounding areas.'' In the unit descriptions, distances between
landmarks marking the upstream or downstream extent of a particular
stream in the unit are given in kilometers (km) and equivalent miles
(mi), as measured tracing the course of the stream, not straight-line
distance.
Unit 1: Econfina Creek, Florida
Unit 1 includes the main stem of Econfina Creek and one of its
tributaries in Bay and Washington counties, Florida, encompassing a
total stream length of 31.4 km (19.5 mi). The main stem of Econfina
Creek as proposed extends from its confluence with Deer Point Lake at
the powerline crossing located 3.8 km (2.3 miles) downstream of Bay
County Highway 388, Bay County, Florida, upstream 28.6 km (17.8 mi) to
Tenmile Creek in Washington County, Florida. Unit 1 also includes the
tributary stream Moccasin Creek from its confluence with Econfina Creek
upstream 2.8 km (1.7 mi) to Ellis Branch in Bay County. Unit 1 is
designated for the Gulf moccasinshell and oval pigtoe (Blalock-Herod
unpub. data 2002-03; Brim Box unpub. data 1996; Williams unpub. data
1993).
Unit 2: Chipola River, Alabama and Florida
Unit 2 includes the main stem of the Chipola River (including the
reach known as Dead Lake) and six of its tributaries, encompassing a
total stream length of 190.0 km (118.1 mi) in Houston County, Alabama;
and in Calhoun, Gulf, and Jackson counties, Florida. The main stem of
the Chipola River as proposed extends from its confluence with the
Apalachicola River in Gulf County, Florida, upstream 144.9 km (90.0 mi)
to the confluence of Marshall and Cowarts creeks in Jackson County,
Florida. A short segment of the Chipola River that flows underground
within the boundaries of Florida Caverns State Park in Jackson County,
Florida, is not included in Unit 2. The downstream extent of each
tributary within the unit is its mouth (its confluence with the water
body named), and the upstream extent is the landmark listed. The
tributaries of the Chipola River included in Unit 2 are: Dry Creek,
[[Page 32761]]
from the Chipola River upstream 7.6 km (4.7 mi) to Ditch Branch in
Jackson County, Florida; Rocky Creek, from the Chipola River upstream
7.1 km (4.4 mi) to Little Rocky Creek in Jackson County, Florida;
Waddells Mill Creek, from the Chipola River upstream 3.7 km (2.3 mi) to
Russ Mill Creek in Jackson County, Florida; Baker Creek, from Waddells
Mill Creek upstream 5.3 km (3.3 mi) to the confluence with Tanner
Springs in Jackson County, Florida; Marshall Creek, from the Chipola
River upstream 13.7 km (8.5 mi) to the Alabama-Florida State line in
Jackson County, Florida (this creek is known as Big Creek in Alabama);
and Big Creek, from the Alabama-Florida State line upstream 7.8 km (4.9
mi) to Double Bridges Creek in Houston County, Alabama.
This unit is designated for the fat threeridge (Brim Box and
Williams 2000, p. 92-93; Miller 1998, p. 54), shinyrayed pocketbook
(Williams unpub. data 2002; Brim Box and Williams 2000, p. 109-110;
Smith unpub. data 2001; Blalock-Herod unpub. data 2000, 2003; Butler
unpub. data 1993, 1994, 1999, 2000); Gulf moccasinshell (Butler unpub.
data 1999, 2002; Brim Box and Williams 2000, p. 113-114; D.N. Shelton
pers. comm. 1998); oval pigtoe (Butler unpub. data 1993, 1999, 2002;
Brim Box and Williams 2000, p. 116-117; Williams unpub. data 2000); and
Chipola slabshell (Butler unpub. data 1993, 2000; Brim Box and Williams
2000, p. 95-96).
Unit 3: Uchee Creek, Alabama
Unit 3 encompasses 34.2 km (21.2 mi) of the main stem of Uchee
Creek from its confluence with the Chattahoochee River upstream to
Island Creek in Russell County, Alabama. This unit is designated for
the shinyrayed pocketbook (Brim Box and Williams 2000, p. 109-110;
Gangloff unpublished data 2005).
Unit 4: Sawhatchee Creek and Kirkland Creek, Georgia
Unit 4 includes the main stems of Sawhatchee Creek and Kirkland
Creek and one tributary of Sawhatchee Creek, encompassing a total
stream length of 37.8 km (23.5 mi) in Early County, GA. The main stem
of Sawhatchee Creek as proposed extends from its confluence with the
Chattahoochee River upstream 28.6 km (17.8 mi) to the powerline
crossing located 1.4 km (0.87 mi) upstream of County Road 15, Early
County, GA. The main stem of Kirkland Creek extends from its confluence
with the Chattahoochee River upstream 6.1 km (3.8 mi) to Dry Creek,
Early County, GA. The tributary, Sheffield Mill Creek, is included from
its confluence with Sawhatchee Creek upstream 3.1 km (1.9 mi) to the
powerline crossing located 2.3 km (1.4 mi) upstream of Sowhatchee Road,
Early County, GA. Unit 4 is designated for the shinyrayed pocketbook,
Gulf moccasinshell, and oval pigtoe (Brim Box and Williams 2000, p.
109-110, 113-114, 116-117; Abbott pers. comm. 2005; Stringfellow pers.
comm. 2003).
Unit 5: Upper Flint River, Georgia
Unit 5 includes the main stem of the Flint River and eight of its
tributaries upstream of Lake Blackshear, plus two tributaries that flow
into Lake Blackshear, encompassing a total stream length of 380.4 km
(236.4 mi) in Coweta, Crawford, Crisp, Dooly, Fayette, Macon,
Meriwether, Peach, Pike, Spalding, Sumter, Talbot , Taylor, Upson, and
Worth counties, Georgia. The main stem of the Flint River in proposed
Unit 5 extends from the State Highway 27 bridge (Vienna Road) in Dooly
and Sumter counties, Georgia (the river is the county boundary),
upstream 247.4 km (153.7 mi) to Horton Creek in Fayette and Spalding
counties, Georgia (the river is the county boundary). The downstream
extent of each tributary within the unit is its mouth (its confluence
with the water body named), and the upstream extent is the landmark
listed. The nine tributary streams in Unit 5 are: Swift Creek, from
Lake Blackshear upstream 11.3 km (7 mi) to Rattlesnake Branch in Crisp
and Worth counties, Georgia (the creek is the county boundary);
Limestone Creek, from Lake Blackshear in Crisp County, Georgia,
upstream 8.8 km (5.5 mi) to County Road 89 in Dooly County, Georgia;
Turkey Creek, from the Flint River upstream 21.7 km (13.5 mi) to Rogers
Branch in Dooly County, Georgia; Pennahatchee Creek, from Turkey Creek
upstream 4.8 km (3 mi) to Little Pennahatchee Creek in Dooly County,
Georgia; Little Pennahatchee Creek, from Pennahatchee Creek upstream
5.8 km (3.6 mi) to Rock Hill Creek in Dooly County, Georgia; Hogcrawl
Creek, from the Flint River upstream 21.6 km (13.4 mi) to Little Creek
in Dooly and Macon counties, Georgia (the creek is the county
boundary); Red Oak Creek, from the Flint River upstream 21.7 km (13.5
mi) to Brittens Creek in Meriwether County, Georgia; Line Creek, from
the Flint River upstream 15.8 km (9.8 mi) to Whitewater Creek in Coweta
and Fayette counties, Georgia (the creek is the county boundary); and
Whitewater Creek, from Line Creek upstream 21.5 km (13.4 mi) to Ginger
Cake Creek in Fayette County, Georgia.
Unit 5 is designated for the shinyrayed pocketbook (Dinkins pers.
comm. 1999, 2003; P.D. Johnson pers. comm. 2003; Brim Box and Williams
2000, p. 109-110; Roe 2000; L. Andrews pers. comm. 2000; Blalock-Herod
unpub. data 1997; Butler and Brim Box 1995, p. 3); Gulf moccasinshell
(Edwards Pittman Environmental 2004; McCafferty pers. comm. 2003;
Dinkins pers. comm. 2002; Brim Box and Williams 2000, p. 113-114;
Andrews pers. comm. 2000; Blalock-Herod unpub. data 1997; Butler and
Brim Box 1995, p. 3); oval pigtoe (Edwards Pittman Environmental 2004;
McCafferty pers. comm. 2003; Dinkins pers. comm. 2002, 2003;
Stringfellow pers. comm. 2000, 2003; Abbott pers. comm. 2001; Brim Box
and Williams 2000, p. 116-117; Andrews pers. comm. 2000; Blalock-Herod
unpub. data 1997); and purple bankclimber (Winterringer CCR pers. comm.
2003; Dinkins pers. comm. 2003; P.D. Johnson pers. comm. 2003; Albanese
pers. comm. 2003 regarding unpub. data from De Genachete and CCR; Brim
Box and Williams 2000, p. 105-106; E. Van De Genachete pers. comm.
1999).
Unit 5 is divided into two maps in the Proposed Regulation
Promulgation section of this proposed rule, one for the southern part
and one for the northern part of the unit. The ``match line'' for
joining these two maps is where the county boundary between Crawford
and Upson counties, Georgia, meets the Flint River.
Unit 6: Middle Flint River, Georgia
Unit 6 includes the main stem of the Flint River between Lake Worth
(impounded by the Flint River Dam near Albany) and the Warwick Dam
(which impounds Lake Blackshear), and nine tributaries, encompassing a
total stream length of 302.3 km (187.8 mi) in Dougherty, Lee, Marion,
Schley, Sumter, Terrell, Webster, and Worth counties, Georgia. The main
stem of the Flint River in Unit 6 extends from Piney Woods Creek in
Dougherty County, Georgia (the approximate upstream extent of Lake
Worth), upstream 39.9 km (24.8 mi) to the Warwick Dam in Lee and Worth
counties, Georgia. The downstream extent of each tributary within the
unit is its mouth (its confluence with the water body named), and the
upstream extent is the landmark listed. The nine tributaries of the
Middle Flint River in Unit 6 are: Kinchafoonee Creek, from the Lee-
Dougherty county line (the approximate upstream extent of Lake Worth)
upstream 107.6 km (66.8 mi) to Dry Creek in Webster County, Georgia;
Lanahassee Creek, from Kinchafoonee
[[Page 32762]]
Creek upstream 9.3 km (5.8 mi) to West Fork Lanahassee Creek in Webster
County, Georgia; Muckalee Creek, from the Lee'Dougherty county line
(the approximate upstream extent of Lake Worth) upstream 104.5 km (64.9
mi) to County Road 114 in Marion County, Georgia; Little Muckalee
Creek, from Muckalee Creek in Sumter County, Georgia, upstream 7.2 km
(4.5 mi) to Galey Creek in Schley County, Georgia; Mill Creek, from the
Flint River upstream 3.2 km (2 mi) to Mercer Millpond Creek in Worth
County, Georgia; Mercer Millpond Creek, from Mill Creek upstream 0.45
km (0.28 mi) to Mercer Millpond in Worth County, Georgia; Abrams Creek,
from the Flint River upstream 15.9 km (9.9 mi) to County Road 123 in
Worth County, Georgia; Jones Creek, from the Flint River upstream 3.8
km (2.4 mi) to County Road 123 in Worth County, Georgia; and Chokee
Creek, from the Flint River upstream 10.5 km (6.5 mi) to Dry Branch
Creek in Lee County, Georgia.
Unit 6 is designated for the shinyrayed pocketbook (Crow CCR pers.
comm. 2004; Edwards Pittman Environmental 2004; Albanese pers. comm.
2003 regarding unpub. data from CCR; DeGarmo unpub. data 2002;
McCafferty pers. comm. 2000, 2001; Golladay unpub. data 2001, 2002; P.
Johnson unpub. data 1999; Blalock-Herod unpub. data 1997; Dinkins pers.
comm. 1995; Brim Box and Williams 2000, p. 109-110), Gulf moccasinshell
(Wisnewski unpub. data 2005; DeGarmo unpub. data 2002; Albanese pers.
comm. 2003 regarding unpub. data from D. Shelton; P. Johnson unpub.
data 1999; Brim Box and Williams 2000, p. 113-114; Weston 1995), oval
pigtoe (Wisnewski unpub. data 2005; Crow CCR pers. comm. 2004; Albanese
pers. comm. 2003 regarding unpub. data from CCR; DeGarmo unpub. data
2002; Stringfellow unpub. data 2002; Golladay unpub. data 2001, 2002;
Brim Box and Williams 2000, p. 116-117; P. Johnson unpub. data 1999;
Blalock-Herod unpub. data 1997; Weston 1995), and purple bankclimber
(Tarbell 2004; Brim Box and Williams 2000, p. 105-106).
Unit 6 is divided into two maps in the Proposed Regulation
Promulgation section of this proposed rule, one for the western part
and one for the eastern part of the unit. The ``match line'' for
joining these two maps is Lake Worth in Dougherty County, Georgia.
Unit 7: Lower Flint River, Georgia
Unit 7 includes the main stem of the Flint River between Lake
Seminole (impounded by the Jim Woodruff Lock and Dam) and the Flint
River Dam (which impounds Lake Worth), and nine tributaries,
encompassing a total stream length of 396.7 km (246.5 mi) in Baker,
Calhoun, Decatur, Dougherty, Early, Miller, Mitchell, and Terrell
counties, GA. The main stem of the Flint River in Unit 7 extends from
its confluence with Big Slough in Decatur County, GA (the approximate
upstream extent of Lake Seminole) upstream 116.4 km (72.3 mi) to the
Flint River Dam in Dougherty County, GA. The downstream extent of each
tributary within the unit is its mouth (its confluence with the water
body named), and the upstream extent is the landmark listed. The nine
tributaries of the Lower Flint River in Unit 7 are: Spring Creek, from
Smith Landing in Decatur County, Georgia (the approximate upstream
extent of Lake Seminole), upstream 74.2 km (46.1 mi) to County Road 35
in Early County, Georgia; Aycocks Creek, from Spring Creek upstream
15.9 km (9.9 mi) to Cypress Creek in Miller County, Georgia; Dry Creek,
from Spring Creek upstream 9.9 km (6.1 mi) to Wamble Creek in Early
County, Georgia; Ichawaynochaway Creek, from the Flint River in Baker
County, Georgia, upstream 68.6 km (42.6 mi) to Merrett Creek in Calhoun
County, Georgia; Mill Creek, from Ichawaynochaway Creek upstream 7.4 km
(4.6 mi) to County Road 163 in Baker County, Georgia; Pachitla Creek,
from Ichawaynochaway Creek upstream 18.9 km (11.8 mi) to Little
Pachitla Creek in Calhoun County, Georgia; Little Pachitla Creek, from
Pachitla Creek upstream 5.8 km (3.6 mi) to Bear Branch in Calhoun
County, Georgia; Chickasawhatchee Creek, from Ichawaynochaway Creek in
Baker County, GA, upstream 64.5 km (40.1 mi) to U.S. Highway 82 in
Terrell County, Georgia; and Cooleewahee Creek, from the Flint River
upstream 15.1 km (9.4 mi) to Piney Woods Branch in Baker County,
Georgia.
Unit 7 is designated for the shinyrayed pocketbook (Gangloff 2005;
McCafferty pers. comm. 2004; Stringfellow unpub. data 2003; Dinkins
pers. comm. 2001, 2003; Golladay unpub. data 2001, 2002; P. Johnson
unpub. data 1999; Albanese pers. comm. 2003 regarding unpub. data from
CCR; Andrews pers. comm. 2000; Blalock-Herod unpub. data 1997; Brim Box
and Williams 2000, p. 109-110; Butler unpub. data 1993), Gulf
moccasinshell (Abbott pers. comm. 2005; Golladay unpub. data 2001,
2002; P. Johnson unpub. data 1999; Brim Box and Williams 2000, p. 113-
114; Butler unpub. data 1998; Blalock-Herod unpub. data 1997), oval
pigtoe (Dinkins pers. comm. 2001; Golladay unpub. data 2001, 2002;
Andrews pers. comm. 2000; Brim Box and Williams 2000, p. 116-117; P.
Johnson unpub. data 1999; Butler unpub. data 1998; Blalock-Herod unpub.
data 1997), and purple bankclimber (S. Carlson unpub. data 2002; Brim
Box and Williams 2000, p. 105-106).
Unit 7 is divided into two maps in the Proposed Regulation
Promulgation section of this proposed rule, one for the western part
and one for the eastern part of the unit. The western part (Map 10)
depicts the Spring Creek system and the eastern part (Map 11) depicts
the lower Flint River system.
Unit 8: Apalachicola River, Florida
Unit 8 includes the main stem of the Apalachicola River and two
distributaries (channels flowing out of the main stem), encompassing a
total stream length of 155.4 km (96.6 mi) in Calhoun, Franklin,
Gadsden, Gulf, Jackson, and Liberty counties, Florida. The main channel
of the Apalachicola River in Unit 8 extends from the downstream end of
Bloody Bluff Island (river mile 15.3 on U.S. Army Corps of Engineers
Navigation Charts) in Franklin County, Florida, upstream to the Jim
Woodruff Lock and Dam in Gadsden and Jackson counties, Florida (the
river is the county boundary). The upstream extent of each distributary
within the unit is its point of departure from the main channel of the
Apalachicola River, and the downstream extent is the landmark listed.
The two distributaries of the Apalachicola River in Unit 6 are: Chipola
Cutoff, from the Apalachicola River in Gulf County, Florida, downstream
4.5 km (2.8 mi) to its confluence with the Chipola River in Gulf
County, Florida; and Swift Slough, from the Apalachicola River in
Liberty County, Florida, downstream 3.6 km (2.2 mi) to its confluence
with the River Styx in Liberty County, Florida.
Unit 8 is designated for the fat threeridge (Brim Box and Williams
2000, p. 92-93; Williams unpub. data 2000; Miller 1998, p. 54, 2000;
Richardson and Yokley 1996, p. 137; Flakes 2001) and purple bankclimber
(Brim Box and Williams 2000, p. 105-106; Miller 1998, p. 55, 2000;
Richardson and Yokley 1996, p. 137; Butler unpub. data 1993; Flakes
2001).
Unit 9: Upper Ochlockonee River, Florida, Georgia
Unit 9 includes the main stem of the Ochlockonee River upstream of
Lake Talquin (impounded by the Jackson Bluff Dam) and three
tributaries, encompassing a total stream length of 177.3 km (110.2 mi)
in Gadsden and
[[Page 32763]]
Leon counties, Florida, and Grady and Thomas counties, Georgia. The
main stem of the Ochlockonee River in Unit 9 extends from its
confluence with Gulley Branch (the approximate upstream extent of Lake
Talquin) in Gadsden and Leon counties, Florida (the river is the county
boundary), upstream to Bee Line Road/County Road 306 in Thomas County,
Georgia. The downstream extent of each tributary within the unit is its
mouth (its confluence with the water body named), and the upstream
extent is the landmark listed. The three tributary streams in Unit 9
are: Barnetts Creek, from the Ochlockonee River upstream 20 km (12.4
mi) to Grady County Road 170/Thomas County Road 74 in Grady and Thomas
counties, Georgia (the creek is the county boundary); West Barnetts
Creek, from Barnetts Creek upstream 10 km (6.2 mi) to GA Highway 111 in
Grady County, Georgia; and Little Ochlockonee River, from the
Ochlockonee River upstream 13.3 km (8.3 mi) to Roup Road/County Road 33
in Thomas County, Georgia.
Unit 9 is designated for the shinyrayed pocketbook (Blalock-Herod
2003, p. 1; McCafferty pers. comm. 2003; Williams unpub. data 1993),
Ochlockonee moccasinshell (Brim Box and Williams 2000, p. 60; Williams
and Butler 1994, p. 64), oval pigtoe (Edwards Pittman Environmental
2004; Blalock-Herod unpub. data 2003; Blalock-Herod 2003, p. 1;
Williams unpub. data 1993), and purple bankclimb