[Federal Register Volume 65, Number 17 (Wednesday, January 26, 2000)]
[Rules and Regulations]
[Pages 4140-4156]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-1746]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AD23


Endangered and Threatened Wildlife and Plants; Designation of 
Critical Habitat for the Woundfin and Virgin River Chub

AGENCY:  U.S. Fish and Wildlife Service, Interior.

ACTION:  Final rule.

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SUMMARY:  We, the Fish and Wildlife Service (Service), designate 
critical habitat for the Virgin River chub (Gila seminuda) and the 
woundfin (Plagopterus argentissimus) in accordance with the Endangered 
Species Act of 1973, as amended. The Virgin River chub and woundfin are 
listed as endangered. Both species occur within the area designated as 
critical habitat. The designation includes portions of the Virgin River 
in Utah, Arizona, and Nevada. We are designating 140.1 kilometers (km) 
(87.5 miles (mi)) of critical habitat for the woundfin (approximately 
12.5 percent of its historical range) and the Virgin River chub (65.3 
percent of its historical range). The majority of the land to be 
designated as critical habitat is under Federal ownership (57.7 
percent) or private ownership (39.9 percent). This critical habitat 
designation includes portions of the mainstem Virgin River and its 
associated 100-year floodplain. Under section 7 of the Endangered 
Species Act (Act) of 1973, as amended, Federal agencies are required to 
ensure that their actions are not likely to destroy or adversely modify 
designated critical habitat. Section 4 of the Act required us to 
consider economic and other impacts prior to making this final decision 
on the size and scope of the designation.

EFFECTIVE DATE:  February 25, 2000.

ADDRESSES:  You may inspect the complete file for this rule, by 
appointment, during normal business hours at the office of the Field 
Supervisor, Ecological Services, U.S. Fish and Wildlife Service, 145 
East 1300 South, Suite 404, Salt Lake City, Utah 84115.

FOR FURTHER INFORMATION CONTACT:  Mr. Reed E. Harris, Field Supervisor, 
Salt Lake City Field Office, at the above address, (801/524-5001).

SUPPLEMENTARY INFORMATION:

Background

    The woundfin (Plagopterus argentissimus) and Virgin River chub 
(Gila seminuda) are currently listed as endangered pursuant to the 
Endangered Species Act (Act) of 1973, as amended (16 U.S.C. 1531 et 
seq.). In the subsequent text, we refer to the woundfin and Virgin 
River chub as ``listed fishes.'' The Virgin River originates in south-
central Utah, running in a southwest direction to northwestern Arizona, 
and southeastern Nevada for approximately 320 km (200 mi) before 
emptying into Lake Mead. Prior to the completion of Boulder (Hoover) 
Dam in 1935, the Muddy River in southeastern Nevada joined the Virgin 
River before the latter emptied into the Colorado River. These two 
rivers now flow separately into the Overton Arm of Lake Mead. The 
Virgin River chub and woundfin have declined in numbers due to the 
cumulative effects of dewatering from numerous diversion projects; 
proliferation of nonnative fishes; and alterations to natural flow, 
temperature, and sediment regimes.

Woundfin

    Based on early records, the original range of the woundfin extended 
from near the junction of the Salt and Verde Rivers at Tempe, Arizona, 
to the mouth of the Gila River at Yuma, Arizona (Gilbert and Scofield 
1898; Minckley 1973). Woundfin were also found in the mainstem Colorado 
River from Yuma (Jordan and Evermann 1896; Meek 1904; Follett 1961) 
upstream to the Virgin River in Nevada, Arizona, and Utah and into La 
Verkin Creek, a tributary of the Virgin River in Utah (Gilbert and

[[Page 4141]]

Scofield 1898; Snyder 1915; Miller and Hubbs 1960; Cross 1975). 
However, because no barriers or habitat considerations exist that would 
have precluded woundfin from existing further upstream in these rivers, 
we believe that the woundfin likely occurred further upstream in the 
Verde, Salt, and Gila Rivers in Arizona.
    Except for the mainstem of the Virgin River, woundfin are 
extirpated from most of their historical range. Woundfin presently 
range from Pah Tempe Springs (also called La Verkin Springs) on the 
mainstem of the Virgin River and the lower portion of La Verkin Creek 
in Utah, downstream to Lake Mead. A single specimen was taken from the 
middle Muddy (Moapa) River, Clark County, Nevada, in the late 1960s. 
However, no additional specimens have been collected from that drainage 
since that time (Deacon and Bradley 1972).
    Adult and juvenile woundfin inhabit runs and quiet waters adjacent 
to riffles with sand and sand/gravel substrates. Adults are generally 
found in habitats with water depths between 0.15 and 0.43 meters (m) 
(0.5 and 1.4 feet (ft)) with velocities between 0.24 and 0.49 meters 
per second (m/s) (0.8 and 1.6 feet per second (ft/s)). Juveniles select 
areas with slower and deeper water, while larvae are found in 
backwaters and stream margins which are often associated with growths 
of filamentous algae. Spawning takes place during the period of 
declining spring flows.

Virgin River Chub

    The Virgin River chub was first described as a full species (Gila 
seminuda) in 1875 (Cope and Yarrow 1875). Later, Ellis (1914) 
considered this chub to be an intermediate between the roundtail chub 
(G. robusta) and bonytail chub (G. elegans), and reduced it to a 
subspecies (G. robusta seminuda) of the roundtail chub. The fish was 
believed to be restricted to the Virgin River between Hurricane, Utah, 
and its confluence with the Colorado River.
    In a recent taxonomic study of the genus Gila using morphological 
and genetic characters, DeMarais et al. (1992) concluded that the prior 
treatment of the Virgin River chub as a subspecies of roundtail chub 
was inappropriate and arbitrary. The authors asserted that full species 
status (Gila seminuda) was warranted for the Virgin River chub, which 
likely arose through introgressive hybridization involving G. robusta 
and G. elegans (DeMarais et al, 1992). Moreover, DeMarais et al. (1992) 
concluded that the chub found in the Muddy (=Moapa) River, a Virgin 
River tributary, was also G. seminuda, although the Muddy River 
population was ``distinctive.'' Prior to this conclusion, this 
geographically isolated population of Virgin River chub was considered 
a separate, unnamed subspecies of roundtail chub (G. robusta spp.), and 
was referred to as the Moapa roundtail chub (Minckley 1973, Smith et 
al. 1977). We, along with the American Fisheries Society and American 
Society of Ichthyologists and Herpetologists Fish Names Committee (Mr. 
Joseph S. Nelson, American Fisheries Society, in litt. 1993) have 
accepted the taxonomic revisions of Gila.
    In past candidate notices of review, we considered the Muddy River 
population of Virgin River chub to be a category 2 candidate species 
(December 30, 1982, 47 FR 58455; January 6, 1989, 54 FR 556; November 
21, 1991, 56 FR 58804). At that time, category 2 candidate species were 
those species for which we had information indicating that listing may 
be appropriate, but did not have enough information on file to support 
issuance of a proposed rule to list. In our February 28, 1996, 
candidate notice of review (61 FR 7596), we discontinued the 
designation of category 2 candidates. The final rule listing the Virgin 
River chub as an endangered species (August 24, 1989; 54 FR 35305) 
specifically excluded the Muddy River population, because at the time 
it was classified as an undescribed subspecies. The Muddy River is not 
included in this final rule designating critical habitat for the Virgin 
River chub because at the time that the proposed critical habitat 
designation and economic analysis were prepared, we did not consider 
the Muddy River population to be listed. Therefore, in order to respond 
in a timely manner and make a final determination with regard to 
critical habitat for the Virgin River chub, this final rule encompasses 
only the mainstem Virgin River. A separate listing determination, which 
will include analyses on the status of the species and whether listing 
the fish in the Muddy River is warranted, will be prepared for this 
population and made available for public review and comment. The 
prudency and determinability of critical habitat for the Muddy River 
population will be addressed at that time.
    The Virgin River chub was first collected in the 1870s from the 
Virgin River near Washington, Utah. Historically, it was collected in 
the mainstem Virgin River from Pah Tempe Springs, Utah, downstream to 
the confluence with the Colorado River in Nevada (Cope and Yarrow 1875; 
Cross 1975), though it may have occurred upstream of that point. 
Presently, the Virgin River chub occurs within the mainstem Virgin 
River from Pah Tempe Springs, Utah, downstream to at least the Mesquite 
Diversion, located near the Arizona-Nevada border.
    Adult and juvenile Virgin River chub select deep runs or pools with 
slow to moderate velocities containing boulders or other instream cover 
over a sand substrate. Generally, larger fish occupy deeper habitats; 
however, there is no apparent correlation with velocity. Chub are 
generally found in velocities ranging up to 0.76 m/s (2.5 ft/s).

Importance of the Virgin River Floodplain

    Preservation of the river channel alone is not sufficient to ensure 
the survival and recovery of the woundfin and Virgin River chub. The 
Virgin River floodplain is integral to preserving the integrity of the 
primary constituent elements (defined below) and maintaining the 
natural dynamics of the Virgin River. Components of a healthy river 
system needed for these fish include the mainstem channel, where water 
is maintained most or all of the year, and upland habitats that are 
inundated during spring flows. Studies of the major floodplain rivers 
of the world have documented the value of flooded bottomlands and 
uplands for fish production (Welcomme 1979). For example, loss of 
floodplain habitats in the Missouri River Basin has reduced fish 
biomass production as much as 98 percent (Karr and Schlosser 1978). 
These seasonally flooded habitats contribute to the biological 
productivity of the river system by producing allochthonous (humus, 
silt, organic detritus, colloidal matter, and plants and animals 
produced outside the river and brought into the river) organic matter 
which provides nutrients and terrestrial food sources to aquatic 
organisms (Hesse and Sheets 1993). The Virgin River contains little 
aquatic vegetation and contains a minimum amount of autochthonous 
(produced within the river) organic matter. Thus, the fauna of the 
Virgin River is heavily dependent on allochthonous energy inputs from 
the floodplain that provides or supports much of the food base. This 
rich, terrestrial food source may enhance fish growth, fecundity, and/
or survival.
    Use of these inundated floodplain areas increases the energy 
available for spawning and is necessary for reproductive success in 
some species (Finger and Stewart 1987). In many cyprinid fishes, 
including these listed fishes, spawning is associated with seasonal 
rains and flooding of rivers. Flood-related changes in the river

[[Page 4142]]

environment induce spawning for many species, while the loss of these 
seasonal changes due to water withdrawals and channel constrictions may 
be a contributing factor limiting recruitment for these fish (Hontele 
and Stacey 1990).
    Protection of floodplain areas also provides the spatial and 
temporal scope for natural physical processes, including flooding, to 
occur (National Research Council 1992). These processes over time shape 
and reshape the river, constantly redefining the physical habitat and 
complexity of the river. Large flow events allow the river to meander, 
thereby creating and recreating the mosaic of habitats necessary for 
the survival and recovery of the listed fishes. As long as this 
physical reshaping occurs, the habitat complexity and biological 
productivity associated with river-floodplain systems necessary for the 
survival and recovery of the listed fishes will be maintained.
    Inundation of floodplain habitats during spring flows also provides 
areas with warmer water temperatures, lower water velocity habitat used 
for resting, and cover from predation. Recent studies in the Colorado 
River system show that the life histories and welfare of native 
riverine fishes are linked to the maintenance of a natural or 
historical flow regime (i.e., hydrological pattern of high spring and 
low autumn and winter flows that vary in magnitude and duration 
depending on annual precipitation patterns and runoff from snowmelt) 
(Tyus and Karp 1989, 1990). Minckley and Meffe (1987) suggest that loss 
of flooding will result in extirpation of many of the native fish 
species in the Colorado River system.

Previous Federal Action

    We listed the woundfin as endangered on October 13, 1970 (35 FR 
16047), and proposed critical habitat on November 2, 1977 (42 FR 
57329). However, on March 6, 1979, we withdrew the proposal for 
critical habitat (44 FR 12382) due to the 1978 amendments to the Act, 
which required proposals to be withdrawn if not finalized within 2 
years. A Woundfin Recovery Plan was originally approved in July 1979 
and subsequently revised on March 1, 1984.
    On August 23, 1978, we proposed listing the Virgin River chub as 
endangered and designating critical habitat (43 FR 37668). We also 
withdrew this proposal (45 FR 64853; September 30, 1980), due to the 
1978 amendments to the Act. On June 24, 1986, we again proposed the 
listing as endangered and the designation of critical habitat for the 
Virgin River chub (51 FR 22949). The final rule to list the Virgin 
River chub as endangered was published on August 24, 1989 (54 FR 
35305). We postponed the designation of critical habitat to allow time 
to undertake an analysis of the economic and other impacts of the 
designation as required by section 4(b)(2) of the Act. When the Virgin 
River chub was listed, the Muddy River form was specifically excluded 
because it was believed to be a separate, unnamed subspecies of 
roundtail chub (Moapa roundtail chub= Gila robusta ssp.).
    On March 18, 1994, the U.S. District Court, Colorado (Court) 
ordered us to designate critical habitat for the Virgin River chub, 
woundfin, and Virgin spinedace (Lepidomeda mollispinis mollispinis) (if 
it became listed under the Act before December 31, 1994). The Court 
ordered that critical habitat be proposed no later than April 1, 1995, 
and be finalized by December 1, 1995. We proposed the Virgin spinedace 
for listing as a threatened species on May 18, 1994 (59 FR 25875), but 
did not include critical habitat in that proposed rule because we 
believed that all three fish species would receive greater conservation 
benefit if critical habitat for all three was designated 
simultaneously. We published a proposed rule designating critical 
habitat for the three fishes on April 5, 1995 (60 FR 17296). On April 
11, 1995, we entered into the Virgin Spinedace Conservation Agreement 
and Strategy with other Federal, State, and private local entities to 
eliminate or reduce impacts threatening the continued existence of the 
Virgin spinedace. A Virgin River Fishes Recovery Plan, including the 
woundfin, Virgin River chub, and Virgin spinedace, was finalized on 
April 19, 1995. Because of the conservation efforts being implemented 
on behalf of the Virgin spinedace, we withdrew the proposed listing and 
critical habitat designation of the Virgin spinedace on February 6, 
1996 (61 FR 4401). Therefore, the Virgin spinedace is no longer 
included in this critical habitat designation.
    Prior to publication of a final rule designating critical habitat 
for the woundfin and Virgin River chub, Congress enacted a moratorium 
on final listing actions and we postponed further actions to finalize 
critical habitat. Disruptions in the listing budget beginning in Fiscal 
Year 1995 and the moratorium on certain listing actions, including 
critical habitat designations, during parts of Fiscal Years 1995 and 
1996 remained in effect until April 26, 1996, when President Clinton 
approved the Omnibus Budget Reconciliation Act of 1996 and exercised 
the authority that the Act gave him to waive the moratorium. By that 
time, we had accrued a serious backlog of listing actions. To deal with 
this backlog, we developed and published Interim (61 FR 9651) and Final 
(61 FR 24722) Listing Priority Guidelines for Fiscal Year 1996. The 
guidelines described a multi-tiered approach to working through the 
listing backlog and identified critical habitat designations as our 
lowest listing priority. On December 5, 1996, we published our Final 
Listing Priority Guidance for Fiscal Year 1997 (61 FR 64475), which 
maintained this prioritization.
    On May 8, 1998, we published our Final Listing Priority Guidance 
for Fiscal Years 1998 and 1999 (63 FR 25502). The designation of 
critical habitat remained our lowest priority. However, in December 
1998, the 10th Circuit Court ruled that we could no longer use this 
justification for not designating critical habitat and ordered us to 
designate critical habitat for the Rio Grande silvery minnow 
(Hybognathus amarus). Shortly after that decision, the plaintiffs in 
the Virgin River fishes case filed a motion requesting that we be 
ordered to finalize critical habitat designation for the woundfin and 
Virgin River chub. On August 27, 1999, the U.S. District Court of 
Colorado ordered us to finalize critical habitat designation for the 
woundfin and Virgin River chub by January 20, 2000.

Critical Habitat

    Section 4(a)(3) of the Act and implementing regulations (50 CFR 
424.12) require that, to the maximum extent prudent and determinable, 
the Secretary of the Interior (Secretary) designate critical habitat at 
the time the species is determined to be endangered or threatened. As 
explained above, critical habitat was delayed for a variety of reasons. 
With this final rule, however, critical habitat is now designated for 
the woundfin and Virgin River chub in the Virgin River.

Definition of Critical Habitat

    Critical habitat is defined in section 3(5)(A) 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) which 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.'' The term ``conservation,'' as defined in section

[[Page 4143]]

3(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 this Act are no longer necessary'' (i.e., the species is recovered 
and removed from the list of endangered and threatened species).
    We are required to base critical habitat decisions upon the best 
scientific and commercial information available (50 CFR 424.12) after 
taking into account economic and other impacts of such designation. In 
designating critical habitat for the woundfin and Virgin River chub, we 
have reviewed the overall approaches to the conservation of the 
woundfin and Virgin River chub undertaken or proposed by local, State, 
and Federal agencies operating within the Virgin River basin and the 
identified steps necessary for the species recovery outlined in the 
Virgin River Fishes Recovery Plan. We also have reviewed available 
information that pertains to the geographic range of the species in the 
Virgin River and the habitat requirements of each species. That 
information includes that received during the public comment periods 
associated with this rulemaking (described below).

Effect of Critical Habitat Designation

    Section 7(a) of the Act, as amended, requires Federal agencies to 
evaluate their actions with respect to any species that is proposed or 
listed as endangered or threatened. Regulations implementing this 
interagency cooperation provision of the Act are codified at 50 CFR 
part 402. Section 7(a)(2) of the Act requires Federal agencies to 
ensure that activities they authorize, fund, or carry out are not 
likely to jeopardize the continued existence of a listed species or to 
destroy or adversely modify its critical habitat. If a Federal action 
may affect a listed species or its critical habitat, the responsible 
Federal agency must enter into formal consultation with us.
    The designation of critical habitat is one of several measures 
available to assist in the conservation and recovery of a species. 
Critical habitat may help focus conservation activities by identifying 
areas that contain essential habitat features (primary constituent 
elements) regardless of whether the areas are currently occupied by the 
listed species. Such designation may alert Federal agencies, States, 
the public, and other organizations to the areas' importance. Critical 
habitat also identifies areas that may require special management 
considerations or protection.
    The designation of critical habitat directly affects only Federal 
agencies, by prohibiting actions they fund, authorize, or carry out 
from destroying or adversely modifying critical habitat. Individuals, 
firms, and other non-Federal entities are not affected by the 
designation of critical habitat so long as their actions do not require 
support by permit, license, funding, or other means from a Federal 
agency.
    An understanding of the interplay of the jeopardy and adverse 
modification standards is necessary to evaluate the likely outcomes of 
both consultation under section 7 and the environmental, economic and 
other impacts of any critical habitat designation. Implementing 
regulations (50 CFR part 402) define ``jeopardize the continued 
existence of'' (a species) and ``destruction or adverse modification 
of'' (critical habitat) in virtually identical terms. ``Jeopardize the 
continued existence of'' means to engage in an action ``that reasonably 
would be expected * * * to reduce appreciably the likelihood of both 
the survival and recovery of a listed species.'' ``Destruction or 
adverse modification'' means a direct or indirect alteration that 
``appreciably diminishes the value of critical habitat for both the 
survival and recovery of a listed species.''
    Common to both definitions is an appreciable detrimental effect on 
both survival and recovery of a listed species. Thus, for most species, 
actions likely to result in destruction or adverse modification of 
critical habitat are nearly always found to jeopardize the species 
concerned. Only in a few instances might an action be found to 
adversely modify critical habitat without also being found to 
jeopardize the continued existence of the species. This situation might 
occur in unoccupied habitat or occupied habitat that may become 
unoccupied in the future. In most cases, the existence of a critical 
habitat designation does not materially affect the outcome of 
consultation. This reality is often in contrast to the public 
perception (and the assumption used in the previous economic analysis 
as described in this final rule) that the adverse modification standard 
sets a lower threshold than the jeopardy standard in all instances. The 
similar nature of the jeopardy and adverse modification standards and 
the application of the standards is true for the listed Virgin River 
fishes as well. The area of the river system being designated as 
critical habitat in this final rule is occupied by the listed fishes.
    Section 4(b)(8) of the Act requires us to describe in any proposed 
or final regulation that designates critical habitat, those activities 
involving a Federal action that may adversely modify such habitat or 
those activities that may be affected by such designation. Activities 
that may destroy or adversely modify critical habitat include those 
that alter the primary constituent elements (defined below) to an 
extent that the value of designated critical habitat for both the 
survival and recovery of a listed species is reduced appreciably.
    Federal activities in the Virgin River basin that may adversely 
modify critical habitat include actions that reduce the volume and 
timing of water flows, destroy or eliminate access to spawning and 
nursery habitat, prevent recruitment, appreciably impact food sources, 
contaminate the river, or significantly increase predation and 
competition by nonnative fishes (Table 1). Examples of such activities 
may include construction and operation of hydroelectric facilities, 
additional irrigation diversions, flood control structures, bank 
stabilization structures, oil and gas drilling, golf courses, and 
resort facilities, as well as mining, grazing, additional pumping to 
meet municipal water demands, and stocking or introduction of nonnative 
fishes.

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Table 1.--Impacts of Woundfin and Virgin River Chub Listing and Critical
                           Habitat Designation
------------------------------------------------------------------------
                                                           Additional
                                Activities impacted by     activities
   Categories of activities      species listing only      impacted by
                                          \1\           critical habitat
                                                         designation \2\
------------------------------------------------------------------------
Federal activities potentially  Activities such as      None.
 affected \3\.                   construction and
                                 operation of
                                 hydroelectric
                                 facilities, flood
                                 control, additional
                                 irrigation
                                 diversions, bank
                                 stabilization, oil
                                 and gas drilling,
                                 mining, grazing,
                                 stocking or
                                 introduction of
                                 nonnative fishes,
                                 that the Federal
                                 Government carries
                                 out that may
                                 jeopardize the
                                 continued existence
                                 of a listed species
                                 (only activities
                                 impacting the
                                 occupied portions of
                                 the river system).
Private activities potentially  Activities such as      None.
 affected \4\.                   additional irrigation
                                 diversions, flood
                                 control, bank
                                 stabilization, oil
                                 and gas drilling,
                                 mining, grazing,
                                 stocking or
                                 introduction of
                                 nonnative fishes,
                                 municipal water
                                 supplies, golf
                                 courses, resort
                                 facilities, water
                                 wheeling, water
                                 leasing, and
                                 dewatering of springs
                                 for municipal and
                                 industrial purposes
                                 that require a
                                 Federal action
                                 (permit,
                                 authorization, or
                                 funding) that may
                                 jeopardize the
                                 continued existence
                                 of the species (only
                                 activities impacting
                                 the occupied portions
                                 of the river system).
------------------------------------------------------------------------
\1\ This column represents the impacts of the final rules listing the
  woundfin (October 13, 1970; 35 FR 16047) and Virgin River chub (August
  24, 1989; 54 FR 35305) under the Endangered Species Act and covers
  land in the occupied portion of the river system only. These rules
  prohibited actions funded, authorized, or carried out by Federal
  agencies that jeopardized the continued existence of the species.
  ``Jeopardizing the continued existence of the species,'' as defined by
  the Act, would result from an action that would appreciably reduce the
  likelihood of the species' survival and recovery.
\2\ This column represents the impacts of the critical habitat
  designation above and beyond those impacts resulting from listing the
  species.
\3\ Activities initiated by a Federal agency.
\4\ Activities initiated by a private entity that may need Federal
  authorization or funding.

    These types of activities have already been examined during formal 
and informal consultations with us since the listing of the species as 
endangered. No additional restrictions to these activities as a result 
of critical habitat designation are anticipated. For example, existing 
Federal activities in the area include the Pah Tempe Pipeline, Halfway 
Wash Project, Lake Powell Pipeline, water wheeling, water leasing, 
Washington Fields Pumpback, and dewatering of springs for municipal and 
industrial purposes.
    Areas outside of critical habitat, containing one or more of the 
primary constituent elements, may still be important for the 
conservation of a species. Some areas do not contain all of the 
constituent elements and may have those missing elements restored in 
the future. Such areas may be important for the long-term recovery of 
the species even if they are not designated critical habitat because 
they may serve to maintain ecosystem integrity, thereby indirectly 
contributing to recovery.
    In summary, designation of critical habitat focuses on the primary 
constituent elements within the defined areas and their contribution to 
the species' recovery, and includes consideration of the species' 
biological needs and factors that will contribute to their recovery 
(i.e., distribution, numbers, reproduction, and viability). In 
evaluating Federal actions, we will consider the actions' impacts on 
the primary constituent elements of water, physical habitat, and 
biological environment (discussed below). The ability of an area to 
provide these constituent elements into the future and to contribute to 
the recovery of the species will also be considered. The potential 
level of allowable impacts or habitat reduction in critical habitat 
will be determined on a case-by-case basis during section 7 
consultation.

Primary Constituent Elements

    In identifying areas as critical habitat, 50 CFR 424.12 provides 
that we consider those physical and biological features that are 
essential to a species' conservation and that may require special 
management considerations or protection. Such physical and biological 
features, as outlined in 50 CFR 424.12, include, but are not limited 
to, the following:
    (1) Space for individual and population growth, and for normal 
behavior;
    (2) Food, water, air, light, minerals, or other nutritional or 
physiological requirements;
    (3) Cover or shelter;
    (4) Sites for breeding, reproduction, rearing of offspring, 
germination, or seed dispersal; and
    (5) Habitats that are protected from disturbance or are 
representative of the historical geographical and ecological 
distributions of a species.
    In determining critical habitat for the woundfin and Virgin River 
chub, we focused on the primary physical and biological elements 
essential to the conservation of each species. Prior to designating an 
area as critical habitat, we assessed the area for all applicable 
constituent elements.
    The primary constituent elements of critical habitat determined 
necessary for the survival and recovery of these Virgin River fishes 
are water, physical habitat, and biological environment. The desired 
conditions for each of these elements are further discussed below.
    Water--A sufficient quantity and quality of water (i.e., 
temperature, dissolved oxygen, contaminants, nutrients, turbidity, 
etc.) that is delivered to a specific location in accordance with a 
hydrologic regime that is identified for the particular life stage for 
each species. This includes the following:
    (1) Water quality characterized by natural seasonally variable 
temperature, turbidity, and conductivity;
    (2) Hydrologic regime characterized by the duration, magnitude, and 
frequency of flow events capable of forming and maintaining channel and 
instream habitat necessary for particular life stages at certain times 
of the year; and
    (3) Flood events inundating the floodplain necessary to provide the 
organic matter that provides or supports the nutrient and food sources 
for the listed fishes.
    Physical Habitat--Areas of the Virgin River that are inhabited or 
potentially habitable by a particular life stage for each species, for 
use in spawning, nursing, feeding, and rearing, or corridors between 
such areas:
Woundfin
    (1) River channels, side channels, secondary channels, backwaters, 
and springs, and other areas which provide access to these habitats;
    (2) Areas inhabited by adult and juvenile woundfin include runs and

[[Page 4145]]

pools adjacent to riffles that have sand and sand/gravel substrates;
    (3) Areas inhabited by juvenile woundfin are generally deeper and 
slower. When turbidity is low, adults also tend to occupy deeper and 
slower habitats;
    (4) Areas inhabited by woundfin larvae include shoreline margins 
and backwater habitats associated with growths of filamentous algae.
Virgin River Chub
    (1) River channels, side channels, secondary channels, backwaters, 
and springs, and other areas which provide access to these habitats; 
and
    (2) Areas with slow to moderate velocities, within deep runs or 
pools, with predominately sand substrates, particularly habitats which 
contain boulders or other instream cover.
    Biological Environment--Food supply, predation, and competition are 
important elements of the biological environment and are considered 
components of this constituent element. Food supply is a function of 
nutrient supply, productivity, and availability to each life stage of 
the species. Predation and competition, although considered normal 
components of this environment, are out of balance due to nonnative 
fish species in many areas. Fourteen introduced species, including red 
shiner (Cyprinella lutrensis), black bullhead (Ameiurus melas), channel 
catfish (Ictalurus punctatus), and largemouth bass (Micropterus 
salmoides), compete with or prey upon the listed fishes. Of these, the 
red shiner is the most numerous and has been the most problematic for 
the listed fishes. Red shiners compete for food and available habitats 
and are known to prey on the eggs and early life stages of the listed 
fishes. Components of this constituent element include the following:
    (1) Seasonally flooded areas that contribute to the biological 
productivity of the river system by producing allochthonous (humus, 
silt, organic detritus, colloidal matter, and plants and animals 
produced outside the river and brought into the river) organic matter 
which provides and supports much of the food base of the listed fishes; 
and
    (2) Few or no predatory or competitive nonnative species in 
occupied Virgin River fishes' habitats or potential reestablishment 
sites.

Critical Habitat Designation

    Woundfin--The area designated as critical habitat for the woundfin 
is the mainstem Virgin River and its 100-year floodplain (as defined 
below), extending from the confluence of La Verkin Creek, Utah, to 
Halfway Wash, Nevada, and includes 59.6 km (37.3 mi) of the mainstem 
Virgin River in Utah, 50.6 km (31.6 mi) in Arizona, and 29.9 km (18.6 
mi) in Nevada (Table 2). This designation totals 140.1 km (87.5 mi) of 
the mainstem Virgin River, which represents approximately 12.5 percent 
of the woundfin's historical habitat. Due to the lack of historical 
data on the distribution of the woundfin in Arizona, this percentage is 
only an estimate. The area of the Virgin River designated as critical 
habitat consists of the remaining occupied habitat for the woundfin, 
and this portion of the Virgin River flows through both public and 
private lands (Table 3).

                 Table 2.--Critical Habitat in Kilometers (Miles) for Virgin River Listed Fishes
----------------------------------------------------------------------------------------------------------------
                         State                                Woundfin      Virgin River chub     State totals
----------------------------------------------------------------------------------------------------------------
Arizona................................................        50.6 (31.6)        50.6 (31.6)        50.6 (31.6)
Nevada.................................................        29.9 (18.6)        29.9 (18.6)        29.9 (18.6)
Utah...................................................        59.6 (37.3)        59.6 (37.3)        59.6 (37.3)
----------------------------------------------------------------------------------------------------------------
        Total..........................................       140.1 (87.5)       140.1 (87.5)       140.1 (87.5)
----------------------------------------------------------------------------------------------------------------


 Table 3.--Critical Habitat Shoreline Ownership in Kilometers (Miles) of
   Critical Habitat Occupied by the Woundfin and Virgin River Chub \1\
------------------------------------------------------------------------
                                       Woundfin and
             Ownership              Virgin River chub       Percent
------------------------------------------------------------------------
Federal...........................        80.9 (50.5)               57.7
State.............................          3.3 (2.1)                2.4
Private...........................        55.9 (34.9)               39.9
------------------------------------------------------------------------
        Total.....................       140.1 (87.5)             100.0
------------------------------------------------------------------------
\1\ Landownership was typically the same on both riverbanks. However, in
  several reaches (1.5 km or less), the river forms a boundary between
  Federal and private lands. Based upon the location of the channel,
  these reaches were identified as either Federal or private, not both.
  Therefore, distances given may be doubled to represent ownership along
  both riverbanks.

    Virgin River Chub--The area designated as critical habitat for the 
Virgin River chub is the mainstem Virgin River and its 100-year 
floodplain (as defined below), extending from the confluence of La 
Verkin Creek to Halfway Wash and is identical to the designation for 
the woundfin (Table 2). The designation for this species represents 
approximately 65.8 percent of the Virgin River chub's historical 
habitat within the Virgin River Basin. The area of the Virgin River 
designated as critical habitat consists of the remaining occupied 
habitat for the Virgin River chub, which flows through both public and 
private lands (Table 3).
    The designation of critical habitat for both listed fishes includes 
the mainstem Virgin River currently occupied by the species. The 100-
year floodplain of the Virgin River is included in the designation of 
critical habitat for both species, but we are designating only those 
portions of the 100-year floodplain that contain at least one of the 
primary constituent elements for critical habitat. We chose the 100-
year floodplain for several reasons. First, the implementing 
regulations of the Act require that critical habitat be defined by 
reference points and lines as found on standard topographic maps of the 
area. The 100-year floodplain, as defined by the Federal Emergency 
Management Agency (FEMA), while not included on standard topographic 
maps, is an area of land that would be inundated by a flood having a 
one

[[Page 4146]]

percent chance of occurring in any given year. It is the Federal 
standard for protection of life and property and is delineated and 
readily available on FEMA floodplain maps. This boundary, rather than 
some other delineation, was primarily chosen for two reasons: (1) The 
biological integrity and natural dynamics of the river system are 
maintained within this area (i.e., allowing the river to meander within 
its main channel in response to large flow events, thereby recreating 
the mosaic of habitats necessary for the survival and recovery of 
Virgin River endangered fishes); and (2) conservation of the 100-year 
floodplain also helps protect the riparian areas and provide essential 
nutrient recharge to the Virgin River, which contributes to successful 
spawning and recruitment of endangered fishes.
    Some developed lands within the 100-year floodplain boundary are 
not considered critical habitat because they do not contain the primary 
constituent elements. These include, but are not limited to, existing 
paved roads, bridges, parking lots, dikes, levees, diversion 
structures, railroad tracks, railroad trestles, water diversion canals 
outside of natural stream channels, active gravel pits, cultivated 
agricultural land, and residential, commercial, and industrial 
developments. These developed areas do not contain the primary 
constituent elements and do not furnish habitat or biological features 
for the listed fishes, and generally will not contribute to the 
species' recovery. However, some activities in these areas (if 
federally funded, authorized, or carried out) may affect the 
constituent elements of the designated critical habitat and, therefore, 
may be affected by critical habitat designation, as discussed later in 
this final rule.

Summary of Changes From the Proposed Rule

    During the public comment period for the proposed rule (60 FR 
17296), we received information provided by the Nevada Division of 
Wildlife and Bio/West, Inc. indicating that very few woundfin or Virgin 
River chub have ever been collected below Halfway Wash, Nevada. The 
backwater effect of the high water line of Lake Mead has resulted in a 
large amount of sand deposition below Halfway Wash. This deposition has 
changed the morphology of the river from a single channel to a highly 
braided river reach consisting of multiple rivulets, thereby reducing 
the gradient of the river and resulting in an extremely shallow 
multiple channeled habitat, not suitable for either woundfin or Virgin 
River chub. Based on this information, we changed the critical habitat 
boundary in Nevada from the highwater level of Lake Mead to Halfway 
Wash. This change reduced the critical habitat in Nevada by 11.6 km 
(7.3 mi) from what was described in the proposed rule. Additionally, 
critical habitat as proposed for the Virgin spinedace (60 FR 17296) was 
formally withdrawn on February 6, 1996 (61 FR 4401). This action 
further reduced the designation by 179 km (112.0 mi).
    One assumption that we used in the economic analysis was that the 
threshold for an action to result in an adverse modification 
determination was less than the threshold for an action to jeopardize 
the continued existence of a species. The economic impacts summarized 
in the proposed rule were based on this assumption. Since the 
development of the economic analysis and subsequent proposed rule 
designating critical habitat in the Virgin River basin, we have 
determined that, in most cases, actions that are likely to result in 
the destruction or adverse modification of critical habitat are nearly 
always found to jeopardize the continued existence of the species 
concerned. This determination is based, in part, on numerous 
consultations concerning listed fish and critical habitat designated in 
the 100-year floodplain in the upper Colorado River basin. These 
consultations have demonstrated little or no difference in the results 
of application of the jeopardy and adverse modification standard. We 
further discuss the effect of this determination in the ``Consideration 
of Economic and Other Impacts'' section of this final rule.
    As originally proposed, the critical habitat designation included 
five separate river reaches (Maddux et al. 1995). We structured the 
proposal this way to coincide with the economic analysis and to 
facilitate exclusion of areas if the economic impacts of designation of 
critical habitat outweighed the benefits, provided that exclusion would 
not result in the extinction of either species. For the final 
designation, we have simplified the boundaries by combining all five 
reaches into a single section of river.

Consideration of Economic and Other Impacts

    Section 4(b)(2) of the Act requires us to consider the economic and 
other relevant impacts in determining whether to exclude any proposed 
area(s) from the final designation of critical habitat. We may exclude 
an area from critical habitat designation if the benefits of its 
exclusion outweigh the benefits of its inclusion in critical habitat, 
unless failure to designate the area would result in extinction of the 
species concerned. In 1995, we conducted an analysis on the potential 
economic impacts of the proposed critical habitat designation 
(Brookshire et al. 1995).
    When we directed the economic analysis in 1995, we assessed the 
biological requirements for the recovery of the listed fishes and the 
regional economic activities as the basis of the analysis. The 
biological requirements needed to ensure recovery of the listed fishes 
include adjustments in water diversions in the Virgin River basin and/
or mitigation of nonflow-related activities within the 100-year 
floodplain. We also took into consideration the effects of potential 
recovery efforts on future water depletions in the basin. The study 
region for the economic analysis included Washington and Iron Counties 
in Utah, Clark County in Nevada, and the portion of Mohave County in 
Arizona located north of the Colorado River.
    We believed that Washington County, Utah, and Clark County, Nevada, 
would be directly affected by any actions taken by the Service on 
behalf of the listed fishes. These counties are presently among the 
fastest growing in the United States. From 1980 to 1990, Washington 
County's population grew by 52 percent, while Clark County's grew by 
62.5 percent. Iron County, Utah, (north of Washington County) is a 
rapidly growing area that is economically closely linked to Washington 
County. Although the Virgin River does not flow through Iron County, 
any economic impacts on Washington County would be felt in Iron County 
as well. The Virgin River also flows through a portion of Mohave County 
in Arizona. This area has a very small population and a modest economic 
base.
    In the 1995 economic analysis, we analyzed the economic impacts of 
insuring that the biological requirements of the listed fishes were met 
in the Virgin River Basin. Our analysis included impacts that were 
attributable to the listing itself, through the requirement that 
Federal agencies consult with us to ensure that their actions do not 
jeopardize the continued existence of the species. Habitat requirements 
of the listed fishes have been addressed by the jeopardy standard in 
each consultation we have done since the fishes were listed. Although 
we separately analyzed the incremental effects of the critical habitat 
designation above and beyond the effects of listing, that separation 
was based on the incorrect assumption that

[[Page 4147]]

the threshold for an action to result in an adverse modification 
determination is less than the threshold for determining that the 
action will likely jeopardize the continued existence of a species. We 
now recognize that our analysis should have been restricted to the 
specific impacts of designating critical habitat, if any, that would 
occur above and beyond the economic impacts of the listing, an 
interpretation upheld by recent case law (New Mexico Cattle Growers 
Association et al. v. United States Fish and Wildlife Service, et al., 
CIV No. 98-0275 BB/DJS-ACE).
    In the economic analysis, we also made an assumption that as a 
species moves from near extinction to recovery, the likelihood that any 
given project will cause adverse modification remains relatively 
constant, while the likelihood of jeopardy decreases. While this 
assumption will hold true in some circumstances, it has turned out to 
be a more complicated situation than initially presumed. Specifically, 
factors that alter the likelihood of jeopardy will only alter the 
likelihood of adverse modification to the extent that they affect 
critical habitat. However, because the adverse modification 
determination has its foundation in the likelihood of survival and 
recovery, as does the jeopardy determination, factors that increase the 
likelihood of adverse modification should logically increase the 
likelihood of jeopardy as well. In other words, adverse modification 
determinations will generally coincide with jeopardy determinations.
    After years of conducting consultations under section 7 of the Act 
on actions affecting both a listed species and its critical habitat, we 
have learned that the two thresholds are nearly identical. In fact, 
biological opinions which conclude that a Federal agency action is 
likely to adversely modify critical habitat but not to jeopardize the 
species for which it is designated are extremely rare historically. 
Although the Service has participated in thousands of formal 
consultations (an estimated 900 in Fiscal Year 1999 alone), no such 
biological opinions have been issued in recent years. The similar 
application of the two standards is true in the specific case of the 
listed Virgin River fishes as well. In this final rule we review the 
results of the economic analysis in light of the correct assumption 
(that the thresholds for adverse modification and jeopardy are usually 
identical.)

Results of the Economic Analysis

    Because the entire economic analysis was based on our incorrect 
assumption that the threshold for an action to result in an adverse 
modification determination is less than the threshold for an action to 
jeopardize the continued existence of a species, we conclude that even 
the small potential impacts attributable to critical habitat 
designation as discussed in the economic analysis, and summarized in 
the proposed rule, were overstated and are primarily attributable to 
the listing of the woundfin and Virgin River chub.
    We have concluded that no incremental economic impacts are 
associated with the critical habitat designation above and beyond the 
effects of listing the species. Therefore, we do not believe that any 
benefit results from excluding any area from designation, nor that any 
benefit of exclusion outweighs the benefit of critical habitat 
designation. Consequently, we have simplified the critical habitat 
boundaries originally described in the proposed rule by combining the 
areas described as five reaches into a single section of river.

Summary of Comments

    On April 5, 1995, we published the proposed rule and notice of 
public hearing in the Federal Register (60 FR 17296). We solicited 
public comment on the proposed critical habitat designation and its 
associated draft economic analysis. The public comment period was open 
from April 5, 1995, to June 5, 1995, and was further extended by 
request to June 20, 1995 (60 FR 31444). During the comment period, we 
conducted a public hearing in St. George, Utah, on May 8, 1995. 
Additional notification of the public hearing and comment period was 
provided by letter to appropriate State agencies, county governments, 
Federal agencies, and other interested parties. Notice of the proposed 
rule, comment period, and the public hearing was also published in the 
Kingman Daily Miner, Desert Valley Times, Daily Spectrum, Deseret News, 
Salt Lake Tribune, Las Vegas Review Journal, and Las Vegas Sun. During 
the comment period, we received 14 written comment letters and 6 people 
testified at the public hearing. Copies of all comments were made 
available to the public at the Washington County Library, Utah.
    Prior to the court order to finalize critical habitat designation, 
on August 9, 1999, we published in the Federal Register (64 FR 43206) a 
notice of availability of a draft environmental assessment on the 
proposed action of designating critical habitat. The public comment 
period was open from August 9, 1999, to September 8, 1999. Additional 
notification of the availability of the draft environmental assessment 
and comment period was provided by letter to appropriate State 
agencies, county governments, Federal agencies, and other interested 
parties. During the comment period, we received 12 written comment 
letters. After a review of all comments received in response to the 
draft environmental assessment, on November 24, 1999, we published a 
notice of availability of the final environmental assessment and 
finding of no significant impact for designation of critical habitat 
for the listed fishes (64 FR 66192) .
    Some of the information provided during the comment periods is 
reflected in this final rule. A summary of the other issues raised in 
the written and oral comments regarding the proposed rule, economic 
analysis, and draft environmental assessment is provided below.
    Issue 1: The critical habitat designation is based on the 
assumption that fish populations have declined in occupied reaches. The 
critical habitat designation is not warranted because numbers of 
individuals of these species may not have declined, although number of 
miles occupied has decreased.
    Service Response: We disagree. At the time of listing, we 
determined that both the woundfin and Virgin River chub warranted 
protection under the Act due to a number of factors. These factors 
included both a decline in the occupied range of the species as well as 
a decline in the abundance of the species. In addition, current data, 
both published and unpublished, indicate that the decline in the 
woundfin population is continuing. Deacon (1988) showed that a 
substantial decline in woundfin occurred in the Virgin River above 
Quail Creek Reservoir and below Pah Tempe Springs between 1976 and 
1993. He attributed this decline, in part, to a decrease in water 
quality because flows above Pah Tempe Springs were diverted at the 
Quail Creek Diversion. Prior to 1985, these flows had previously 
diluted the high saline input from Pah Tempe Springs. Holden and Zucker 
(1996) analyzed data from 1976-1993 that showed a very clear long-term 
decline of woundfin at long-term sampling stations in Utah, Arizona, 
and Nevada. When they plotted the data as number of woundfin caught per 
seining effort per year, they found a statistically significant 
negative trend over time (p  0.05) at all stations except one during 
the fall season, indicating an overall decline in the woundfin 
population. Monitoring data from the Utah Division of Wildlife 
Resources (unpublished data, Recovery Team Meeting Minutes, April 29, 
1999) show a substantial

[[Page 4148]]

decline from 1994 (total number=456 (spring), 604 (fall)) to 1999 
(total number=77 (spring), 162 (fall)).
    Anecdotal, historical information suggests that Virgin River chub 
were very abundant before the 1900s and that the abundance and range of 
Virgin River chub has declined substantially throughout its range in 
Utah, Arizona, and Nevada since white settlement and water development. 
Reasons for this decline are thought to be mainly habitat destruction. 
Habitat is degraded through dewatering of the river system such that 
some areas are inundated by reservoirs and other areas are completely 
dewatered. Also, competition from nonnative species which may prey on 
young life-stages of Virgin River chub may contribute to population 
declines (Holden 1977).
    Virgin River chub have the lowest densities of any native fish in 
the Virgin River (Radant and Coffeen, 1986; Hardy and Addley 1994). 
However, observed numbers may or may not reflect actual abundance. 
Because Virgin River chub occupy deep holes and habitats that are often 
logistically difficult to sample, catch rates can be erratic and 
sampling can be difficult to standardize. Based on the long-term data 
available, Virgin River chub show a general decline in Utah, Arizona, 
and Nevada, particularly since the mid-1980s. Yet in some areas (below 
Hurricane Bridge and below Washington Diversion) numbers are stable or 
within the range of variability noted in the late 1970s and early 1980s 
(Hardy and Addley 1994). Hardy and Addley are careful to note that 
declines may be due to droughts and other natural climatic changes. 
Natural droughts are no doubt exacerbated by water development and the 
human need for water during these years. More recent data are being 
analyzed to determine the current status of Virgin River chub and to 
determine if declining trends continued through the late 1990s.
    Issue 2: The lower portion of La Verkin Creek should be included as 
critical habitat for the woundfin.
    Service Response: Although woundfin are occasionally collected in 
this reach, we are aware of no data that indicate that this area is 
being used for reproduction or as a nursery or that it is essential for 
the conservation of the species. Therefore, it is not included in this 
final critical habitat designation.
    Issue 3: Why did we not include the Muddy River in Nevada as 
critical habitat for the Virgin River chub?
    Service Response: Please see our discussion of the Muddy River 
population in the Background section of this final rule. Because the 
Muddy River population was not listed, critical habitat designation is 
not appropriate. However, we intend to conduct a separate listing 
determination for the Muddy River population, which will include an 
analysis of the status of the species and a determination about the 
prudency and determinability of a critical habitat designation.
    Issue 4: The area from Quail Creek Diversion to Pah Tempe Springs 
should be included in the critical habitat designation for the 
woundfin.
    Service Response: While it is possible that this area was 
historical habitat for the Virgin River chub, woundfin have never been 
found in this reach. It is a high-gradient reach of the river that has 
gone dry annually for the past 80 years. When critical habitat was 
proposed, this reach of the river was left out because it was dry 
dammed. Since critical habitat was proposed, 3 cfs of flows have been 
restored to this reach of the river. However, since that time only one 
Virgin River chub has been collected in this reach of the Virgin River. 
We do not believe that this reach provides those physical or biological 
features essential to the conservation of either species.
    Issue 5: Additional streams in Arizona should be designated as 
critical habitat.
    Service Response: On July 24, 1985, we proposed the reintroduction 
of the woundfin into the Gila River drainage in Arizona and determined 
this population to be ``nonessential experimental'' in accordance with 
section 10(j) of the Act (50 FR 30188). The Act prohibits inclusion of 
nonessential experimental population areas in critical habitat 
designations.
    Issue 6: The Virgin River in Utah was segmented into numerous 
reaches for designation; no segmenting was done in Nevada or Arizona.
    Service Response: Please see our discussion under the ``Summary of 
Changes to the Proposed Rule'' section of this final rule.
    Issue 7: How is the 100-year floodplain defined, and which parts of 
the floodplain are critical habitat?
    Service Response: Please see the discussion under the ``Critical 
Habitat Designation'' section of this proposed rule.
    Issue 8: A 10-year floodplain designation should be sufficient 
because the riparian community is maintained at this flow level.
    Service Response: Critical habitat, among other things, is intended 
to identify areas that may require special management protection or 
consideration. Our intention in designating a portion of the floodplain 
as critical habitat is to encompass not only the area which provides a 
major source of food and nutrients to the river, but also the area 
within which the river meanders. Only areas that contain at least one 
of the primary constituent elements are considered critical habitat. 
Critical habitat that would encompass a 10-year floodplain would not 
contain these attributes. Moreover the selection of the 100-year 
floodplain is consistent with and supports the goals of Virgin River 
Management Plan (1999) and the Proposed Virgin River Resource 
Management and Recovery Program, both of which contain provisions for 
the protection and enhancement of the 100-year floodplain.
    Issue 9: Critical habitat designation is not prudent because of 
preparation of the Virgin River Management Plan.
    Service Response: As discussed in the implementing regulations at 
50 CFR 424.12, critical habitat is considered not prudent when one or 
more of the following situation exists:
    (1) The species is threatened by taking or other human activity, 
and identification of critical habitat can be expected to increase the 
degree of such threat to the species, or
    (2) Such designation of critical habitat would not be beneficial to 
the species.
    In the absence of any information that indicates that critical 
habitat will increase the degree of threat to a species threatened by 
taking or other human activity, any small benefit of designation 
requires that the designation be found prudent. Although we supported 
development of the Virgin River Management Plan (1999), this plan does 
not increase the degree of threat to the species nor negate any 
benefits that may be provided to the species from critical habitat 
designation. Therefore, such designation must be found prudent. The 
extent to which this plan will protect the Virgin River is still 
unknown. Additionally, this plan only covers the Utah portion of the 
habitat. We anticipate that the Virgin River Management Plan and 
critical habitat designation will complement each other.
    Issue 10: The Service should do NEPA on critical habitat 
designation.
    Service Response: Please see our discussion under the ``Required 
Determinations'' section of this final rule.
    Issue 11: The designation does not give full consideration to 
existing and future water rights.
    Service Response: Critical habitat designation for the Virgin River 
listed fishes does not modify nor nullify any existing State water law, 
compact agreement, or treaty. Impacts to water development 
opportunities within the States are mainly attributable to the effects 
of listing these species. It is our

[[Page 4149]]

intent to fully consider State water law, interstate compact 
agreements, and treaties in protecting and recovering the listed 
fishes. As an example, we worked with the State of Utah and the WCWCD 
to develop a Virgin River Management Plan. This plan is intended to 
address both the needs for future water development and recovery of the 
listed fishes consistent with State water laws and other agreements.

Issues and Responses Pertaining to the Economic Analysis

    Because the entire economic analysis was based on our incorrect 
assumption that the threshold for an action to result in an adverse 
modification determination is less than the threshold for an action to 
jeopardize the continued existence of a species, in this final rule we 
have concluded that even the small, potential impacts attributable to 
critical habitat designation as discussed in the economic analysis, and 
summarized in the proposed rule, were overstated and are primarily 
attributable to the listing of the woundfin and Virgin River chub. 
Although many of the points raised by various commentors on the 
economic analysis are no longer relevant given our conclusions about 
the economic impacts of critical habitat, we offer the following 
responses to the issues raised about the analysis.
    Issue 12: The economic analysis incorrectly assumes that converting 
agriculture to secondary/culinary water will reduce current flows to 
the river.
    Service Response: The economic analysis assumed that converting 
agricultural water to Municipal and Industrial (M&I) water might result 
in decreased river flows. The Utah State Water Plan for the Virgin 
River Basin reports water depletion figures for agricultural use to be 
45 percent and for M&I use to be 63 percent. Therefore, converting 
agricultural use to M&I would result in a net decrease in water returns 
of 19 percent. Although return flows may be greater than those used in 
the economic analysis, the points at which these flows are returned to 
the river remain unknown.
    Issue 13: The economic analysis did not assess impacts to Mohave 
County, Arizona.
    Service Response: The majority of Mohave County's economic activity 
falls outside of the Virgin River study area, however, a small part of 
Mohave County, was included, mainly around the town of Litchfield, 
Arizona. There is little economic activity in this part of Mohave 
County, and it includes 0.39 percent of the total population of the 
study area. Consequently, the economic activity occurring in Mohave 
County was shared out of the total activity for the Virgin River area 
based on population. This activity was then incorporated into the Clark 
County analysis.
    Issue 14: The Washington County Water Conservancy District's 
(WCWCD) water plans should have been incorporated into the economic 
analysis, and sensitivity analyses regarding the hydrologic assumptions 
should have been conducted.
    Service Response: The WCWCD's water plans, as represented by the 
report ``Population Projections and Future Water Demands'', prepared by 
Boyle Engineering (1994) for WCWCD, were, in fact, used in creating the 
baseline scenario. The hydrologic assumptions were structured such that 
the resulting economic analysis always yielded a worst-case set of 
economic impacts. Thus, sensitivity analysis would only lower the 
impacts presented in the report.
    Issue 15: The Service's choice of the modeling methodology and the 
choice of discount rates used in the economic analysis were presented 
without explanation of why other models or discount rates were 
rejected.
    Service Response: The Act requires the calculation of the economic 
impacts of critical habitat designation. The use of the contingent 
valuation method for inclusion in cost-benefit analysis is not germane. 
Our use of input-output analysis yielded both the direct and indirect 
impacts associated with recovery needs of the listed fishes. Regarding 
the discount rate, the discounting procedures and assumptions used 
represent the ``industry standard.'' The extant economic literature 
clearly calls for a positive discount rate for economic analyses 
addressing water allocation issues.
    Issue 16: Private landowner effects, water right reallocations, 
loss of open space, and community character should have been addressed 
by the economic analysis.
    Service Response: There are no additive impacts to private property 
owners from critical habitat designation that were not present when the 
species were listed. If Federal funding or Federal permits are required 
for a private action, the Federal action agency must then consult with 
the Service. All transactions associated with the reallocation of water 
are voluntary market transactions and are not impacts of this action. 
The extent to which the community chooses to allow the loss of open 
space and changes in community character is beyond the scope of the 
economic analysis. It should be noted, however, that the designation of 
critical habitat along another river-floodplain system, the 100-year 
floodplain of the Colorado River, has not precluded the setting aside 
of open space or development of parks and trails within the floodplain 
or adjacent to the river.
    Issue 17: It was improper to attribute benefits of water 
conservation to critical habitat designation in the economic analysis.
    Service Response: Water conservation will be realized, with or 
without the listed fishes or a critical habitat designation, by water 
management and conservation measures currently being implemented or 
planned in the future within the study area, in particular, Washington 
County. The economic analysis did not attribute the benefits of water 
conservation to listed fishes recovery and conservation. Rather, the 
water conservation scenario serves to demonstrate that the economic 
impacts of the listed fishes including designation of critical habitat 
can be mitigated with moderate conservation efforts.
    Issue 18: The economic analysis did not document the gross overuse 
and waste of water in Washington County.
    Service Response: The report ``Population Projections and Future 
Water Demands'', prepared by Boyle Engineering (1994) for WCWCD 
addressed these matters. Further analysis in these regards is beyond 
the scope of the economic analysis.
    Issue 19: Not enough weight is given in the economic analysis to 
the consequences of the conversions of agricultural lands in Washington 
County due to critical habitat.
    Service Response: The agricultural lands conversions that are 
projected to occur during the economic analysis study period are 
generated by the population growth that is projected for the region, 
not by the needs of the listed fishes or the designation of critical 
habitat. These agricultural lands are, in fact, incorporated in the 
baseline projection of the economy without taking the fish needs into 
consideration. The fish needs may accelerate the retirement of 
agricultural water rights in order to maintain water in the Virgin 
River for the listed fishes and still allow for water development to 
occur to meet the needs of a growing human population. This incremental 
retirement of water and conversion of land is attributable mainly to 
the listing of these fishes and was incorporated into the economic 
analysis.
    Issue 20: The time period for the economic analysis is too short 
and omits the long term impacts of the designation of critical habitat.

[[Page 4150]]

    Service Response: The study period for the economic analysis (1995-
2040) was selected for the reasons described previously in this rule. 
By the end of this period, the population of Washington County is 
projected to be 380,600 people. Development projections undertaken by 
Boyle Engineering (1994) place the maximum population of Washington 
County at approximately 350,000 at population density levels consistent 
with the present lifestyles of the area. Thus, the population will have 
reached a steady state by the end of the study period used in the 
economic analysis and further impacts are not anticipated.
    The comment further assumes that water maintained to meet the flow 
needs of the fish in critical habitat is lost to the national economy. 
While the Washington County area cannot develop this water, Las Vegas, 
Nevada, could use it after it reaches Halfway Wash. From a national 
perspective, the water may well have a higher value in Las Vegas than 
in Washington County, Utah, because of the larger, more diverse economy 
in Clark County, Nevada.
    Issue 21: The retirement of agricultural lands is not correctly 
addressed in the economic analysis. If land retirements are market 
driven, then the low productivity lands will be converted first and the 
high productivity lands last.
    Service Response: This point is correct. The economic analysis uses 
the average (county-level) productivity to value all agricultural 
lands. This approach overstates the economic impacts due to the listed 
fishes and critical habitat designation because the discounted present 
value of agricultural retirements is higher when the average land value 
is used. This is consistent with the approach calculating the worst-
case economic impacts.
    Issue 22: The economic analysis does not measure the national 
efficiency effects of critical habitat designation.
    Service Response: In accordance with the Act and the regulations 
that implement it, the final designation of critical habitat is made on 
the basis of the best available scientific data, after taking into 
consideration the probable economic and other impacts of the 
designation upon proposed or ongoing activities. The national 
efficiency effects are computed and reported in the economic analysis 
prepared by Brookshire et al. 1995 (see Chapter 8) and summarized in 
the proposed rule. The economic analysis discusses the conditions under 
which the factor payments computed from the input-output analysis may 
be used to value the national efficiency changes.

Required Determinations

Regulatory Planning and Review

    In accordance with Executive Order 12866, this action was submitted 
for review by the Office of Management and Budget. This final rule 
identifies the areas being designated as critical habitat for the 
woundfin and Virgin River chub. The designation will not have an annual 
economic effect of $100 million. Our summary of the economic impacts of 
designation is discussed earlier in this final rule. This rule will not 
create inconsistencies with other agencies' actions. This rule will not 
materially affect entitlements, grants, user fees, loan programs, or 
the rights and obligations of their recipients. Proposed and final 
rules designating critical habitat for listed species are issued under 
the authority of the Act. Critical habitat regulations are issued under 
procedural rules contained in 50 CFR part 424. Based on previous formal 
and informal consultations with other Federal agencies under section 7 
of the Endangered Species Act, the Service has determined that there 
are no economic impacts of critical habitat designation above and 
beyond the impacts of the original listing of the species. Cases 
identified in the economic analysis as a potential economic impact of 
critical habitat designation are actions that would also result in a 
finding of ``jeopardize the continued existence of the species'' during 
section 7 consultation. Thus, any economic impact associated with the 
Virgin River chub and woundfin is one incurred by the original listing 
of the species, not by this critical habitat designation.

Regulatory Flexibility Act

    This rule will not have a significant economic effect on a 
substantial number of small entities as defined under the Regulatory 
Flexibility Act (5 U.S.C. 601 et seq.). As explained previously in this 
final rule, the designation will not have economic effects above and 
beyond those attributed to the listing of the species. This is because 
the prohibition against destroying or adversely modifying critical 
habitat is essentially duplicative of the prohibition against 
jeopardizing the continued existence of the species, and therefore, 
there are no additional economic effects that are not already incurred 
by the listing of the species.

Small Business Regulatory Enforcement Fairness Act

    This rule is not a major rule under 5 U.S.C. 804(2), the Small 
Business Regulatory Enforcement Fairness Act. This rule does not have 
an annual effect on the economy of $100 million or more. As explained 
in this rule, we do not believe that the designation will have economic 
effects above and beyond those attributed to the listing of the 
species. This rule will not cause a major increase in costs or prices 
for consumers, individual industries, Federal, State, or local 
government agencies, or geographic regions, because the designation 
will not have significant economic effects above and beyond the listing 
of the species. This rule does not have significant adverse effects on 
competition, employment, investment, productivity, innovation, or the 
ability of U.S.-based enterprises to compete with foreign-based 
enterprises.

Unfunded Mandates Reform Act (2 U.S.C. 1501 et seq.)

    Based on our analysis of the economic impacts of this rule as 
discussed above, and in accordance with the Unfunded Mandates Reform 
Act (2 U.S.C. 1501 et seq.), this rule will not significantly affect 
small governments because it will not place additional burdens on small 
(State, local, or Tribal) governments. This rule will not produce a 
Federal mandate of $100 million or greater in any year (i.e., it is not 
a significant regulatory action under the Unfunded Mandates Reform 
Act.)

Takings

    In accordance with Executive Order 12630, the rule does not have 
significant takings implications. A takings implication assessment is 
not required. Although the critical habitat designation includes 55.9 
kilometers of privately owned shoreline of the mainstem Virgin River, 
this final rule will not ``take'' private property rights and will not 
alter the value of private property. Critical habitat designation is 
only applicable to Federal lands, or to private lands if a Federal 
nexus exists (i.e., if a Federal agency authorizes or funds an action 
on private land). Private actions without a federal nexus on private 
land are not subject to any critical habitat prohibitions. Any private 
actions on private land that have a Federal nexus are already subject 
to consultation under section 7 of the Endangered Species Act. Because 
we have identified no economic effects of critical habitat designation 
above and beyond those that have accrued from the listing of these 
species, there are no takings implications.

Federalism

    In accordance with Executive Order 13132, this final rule will not 
affect the structure or role of States, and will not have direct, 
substantial, or significant

[[Page 4151]]

effects on States. As previously stated, critical habitat is applicable 
only to Federal lands or to non-Federal lands to the extent that 
activities require Federal funding or permitting. Also, we have 
determined that additional economic impacts would not result from this 
critical habitat designation.
    In keeping with Department of the Interior policy, we requested 
information from and coordinated development of the critical habitat 
proposal with the appropriate State resource agencies in Utah, Arizona, 
and Nevada. On August 9, 1999, we published in the Federal Register (64 
FR 43206) a notice of availability of a draft environmental assessment 
on the proposed action of designating critical habitat. The public 
comment period was open from August 9, 1999, to September 8, 1999. 
Additional notification of the availability of the draft environmental 
assessment and comment period was provided by letter to appropriate 
State agencies, county governments, Federal agencies, and other 
interested parties. During the comment period, we received 12 written 
comment letters, which were considered in finalizing this rule.
    It is our intent to fully consider State water law, interstate 
compact agreements, and treaties in protecting and recovering the 
listed fishes. As an example, we worked with the State of Utah and the 
WCWCD to develop a Virgin River Management Plan (1999). This plan is 
intended to address both the needs for future water development and 
recovery of the listed fishes consistent with State water laws and 
other agreements. The selection of the 100-year floodplain as the 
boundary for this critical habitat designation is consistent with and 
supports the goals of the Virgin River Management Plan and the Proposed 
Virgin River Resource Management and Recovery Program, both of which 
involve the State of Utah.

Civil Justice Reform

    In accordance with Executive Order 12988, the Office of the 
Solicitor has determined that the rule does not unduly burden the 
judicial system and does meet the requirements of sections 3(a) and 
3(b)(2) of the Order. The final designation of critical habitat for the 
woundfin and Virgin River chub has been reviewed extensively. Every 
effort has been made to ensure that the rule contains no drafting 
errors, provides clear standards, simplifies procedures, reduces 
burden, and is clearly written such that litigation risk is minimized.

Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.)

    This rule does not contain any information collection requirements 
for which Office of Management and Budget approval under the Paperwork 
Reduction Act is required.

National Environmental Policy Act

    It is our position that, outside the Tenth Circuit, we do not need 
to prepare environmental analyses as defined by the NEPA in connection 
with designating critical habitat under the Endangered Species Act of 
1973, as amended. We published a notice outlining our reasons for this 
determination in the Federal Register on October 25, 1983 (48 FR 
49244). This assertion was upheld in the courts of the Ninth Circuit 
(Douglas County v. Babbitt, 48 F.3d 1495 (9th Cir. Ore. 1995), cert. 
denied 116 S. Ct. 698 (1996)). However, when the range of the species 
includes States within the Tenth Circuit, pursuant to the Tenth Circuit 
ruling in Catron County Board of Commissioners v. U.S. Fish and 
Wildlife Service, 75 F.3d 1429 (10th Cir. 1996), we undertake a NEPA 
analysis for critical habitat designation. We have completed that 
analysis through an Environmental Assessment and Finding of No 
Significant Impact.

Government-to-Government Relationship With Tribes

    In accordance with the President's memorandum of April 29, 1994, 
``Government-to-Government Relations with Native American Tribal 
Governments'' (59 FR 22951) and procedures outlined by the Department 
of the Interior (512 DM 2), we recognize our responsibility to work 
with federally recognized Tribes on a Government-to-Government basis. 
Moreover, the 1997 Secretarial Order on Native Americans and the Act 
clearly states that Tribal lands should not be designated unless 
absolutely necessary for the conservation of the species. According to 
the Secretarial Order, ``Critical habitat shall not be designated in 
such areas [an area that may impact Tribal trust resources] unless it 
is determined essential to conserve a listed species.'' We are unaware 
of any Tribal lands containing habitat essential to the conservation of 
the listed fishes.

References Cited

    A complete list of all references cited is available upon request 
from the Field Supervisor, Salt Lake City Field Office (see ADDRESSES 
section).

Authors

    The primary authors of this rule are Henry R. Maddux and Janet 
Mizzi, previously of our Salt Lake City Field Office, Patty Stevens of 
our Denver Regional Office, and Keith Rose of our Salt Lake City Field 
Office (see ADDRESSES section).

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Reporting and 
recordkeeping requirements, Transportation.

Regulation Promulgation

    Accordingly, we amend part 17, subchapter B of chapter I, title 50 
of the Code of Federal Regulations, as set forth below:

PART 17--[AMENDED]

    1. The authority citation for part 17 continues to read as follows:

    Authority:  16 U.S.C. 1361-1407; 16 U.S.C. 1531-1544; 16 U.S.C. 
4201-4245; Pub. L. 99-625, 100 Stat. 3500, unless otherwise noted.


Sec. 17.11  [Amended]

    2. Amend section 17.11(h) by revising the entry in the critical 
habitat column of the entry for ``Chub, Virgin River,'' and 
``Woundfin'', under FISHES, to read as follows:


Sec. 17.11  Endangered and threatened wildlife.

* * * * *
    (h) * * *

--------------------------------------------------------------------------------------------------------------------------------------------------------
                         Species                                                     Vertebrate
---------------------------------------------------------                         population where                   When        Critical       Special
                                                             Historic range         endangered or       Status      listed        habitat        rules
            Common name                Scientific name                               threatened
--------------------------------------------------------------------------------------------------------------------------------------------------------
              FISHES
                   *                  *                  *                  *                  *                  *                  *
Chub, Virgin River................  Gila robusta           U.S.A. (AZ, NV, UT)  ........do..........          E       361     Sec.  17.95(e)         NA
                                     seminuda.

[[Page 4152]]

 
                   *                  *                  *                  *                  *                  *                  *
Woundfin..........................  Plagopterus           U.S.A. (AZ, NV, UT),  Entire, except Gila           E     2,193     Sec.  17.95(e)         NA
                                     argentissimus.        Mexico.               River drainage, AZ,
                                                                                 NM.
                   *                  *                  *                  *                  *                  *                  *
--------------------------------------------------------------------------------------------------------------------------------------------------------


    3. Amend Section 17.95(e) by adding critical habitat of the Virgin 
River chub (Gila robusta seminuda) and woundfin (Plagopterus 
argentissimus) in the same alphabetical order as these species occur in 
17.11(h).


Sec. 17.95  Critical habitat-fish and wildlife.

* * * * *
    (e) * * *
* * * * *
Virgin River Chub (Gila seminuda)
    Legal descriptions for St. George (Utah-Arizona) and Littlefield 
(Arizona) were obtained from the 1987 Bureau of Land Management (BLM) 
maps (Surface Management Status 30 x 60 Minute Quadrangle). Legal 
descriptions for Overton (Nevada-Arizona) were obtained from the 1989 
BLM maps (Surface Management Status 30 x 60 Minute Quadrangle). The 
100-year floodplain for many areas is detailed in Flood Insurance Rate 
Maps (FIRM) published by and available through the Federal Emergency 
Management Agency (FEMA). In areas where a FIRM is not available, the 
presence of alluvium soils or known high water marks can be used to 
determine the extent of the floodplain. Only areas of floodplain 
containing at least one of the constituent elements are considered 
critical habitat. Critical habitat designated for the Virgin River chub 
is as follows:
    Utah, Washington County; Arizona, Mohave County; Nevada, Clark 
County. The Virgin River and its 100-year floodplain from its 
confluence with La Verkin Creek, Utah in T.41S., R.13W., sec.23 (Salt 
Lake Base and Meridian) to Halfway Wash, Nevada T.15S., R.69E., sec.6 
(Salt Lake Base and Meridian).
    The primary constituent elements of critical habitat determined 
necessary for the survival and recovery of these Virgin River fishes 
are water, physical habitat, and biological environment. The desired 
conditions for each of these elements are further discussed below.
    Water--A sufficient quantity and quality of water (i.e., 
temperature, dissolved oxygen, contaminants, nutrients, turbidity, 
etc.) that is delivered to a specific location in accordance with a 
hydrologic regime that is identified for the particular life stage for 
each species. This includes the following:
    1. Water quality characterized by natural seasonally variable 
temperature, turbidity, and conductivity;
    2. hydrologic regime characterized by the duration, magnitude, and 
frequency of flow events capable of forming and maintaining channel and 
instream habitat necessary for particular life stages at certain times 
of the year; and
    3. flood events inundating the floodplain necessary to provide the 
organic matter that provides or supports the nutrient and food sources 
for the listed fishes.
    Physical Habitat--Areas of the Virgin River that are inhabited or 
potentially habitable by a particular life stage for each species, for 
use in spawning, nursing, feeding, and rearing, or corridors between 
such areas:
    1. River channels, side channels, secondary channels, backwaters, 
and springs, and other areas which provide access to these habitats; 
and
    2. areas with slow to moderate velocities, within deep runs or 
pools, with predominately sand substrates, particularly habitats which 
contain boulders or other instream cover.
    Biological Environment--Food supply, predation, and competition are 
important elements of the biological environment and are considered 
components of this constituent element. Food supply is a function of 
nutrient supply, productivity, and availability to each life stage of 
the species. Predation and competition, although considered normal 
components of this environment, are out of balance due to nonnative 
fish species in many areas. Fourteen introduced species, including red 
shiner (Cyprinella lutrensis), black bullhead (Ameiurus melas), channel 
catfish (Ictalurus punctatus), and largemouth bass (Micropterus 
salmoides), compete with or prey upon the listed fishes. Of these, the 
red shiner is the most numerous and has been the most problematic for 
the listed fishes. Red shiners compete for food and available habitats 
and are known to prey on the eggs and early life stages of the listed 
fishes. Components of this constituent element include the following:
    1. Seasonally flooded areas that contribute to the biological 
productivity of the river system by producing allochthonous (humus, 
silt, organic detritus, colloidal matter, and plants and animals 
produced outside the river and brought into the river) organic matter 
which provides and supports much of the food base of the listed fishes; 
and
    2. few or no predatory or competitive nonnative species in occupied 
Virgin River fishes' habitats or potential reestablishment sites.

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[[Page 4154]]


Woundfin (Plagopterus argentissimus)
    Legal descriptions for St. George (Utah-Arizona) and Littlefield 
(Arizona) were obtained from the 1987 BLM maps (Surface Management 
Status 30 x 60 Minute Quadrangles). Legal descriptions for Overton 
(Nevada-Arizona) were obtained from the 1989 BLM maps (Surface 
Management Status 30 x 60 Minute Quadrangles). The 100-year floodplain 
for many areas is detailed in Flood Insurance Rate Maps (FIRM) 
published by and available through the Federal Emergency Management 
Agency (FEMA). In areas where a FIRM is not available, the presence of 
alluvium soils or known high water marks can be used to determine the 
extent of the floodplain. Only areas of floodplain containing at least 
one of the constituent elements are considered critical habitat. 
Critical habitat designated for the woundfin is as follows:
    Utah, Washington County; Arizona, Mohave County; Nevada, Clark 
County. The Virgin River and its 100-year floodplain from its 
confluence with La Verkin Creek, Utah in T.41S., R.13W., sec.23 (Salt 
Lake Base and Meridian) to Halfway Wash, Nevada T.15S., R.69E., sec.6 
(Salt Lake Base and Meridian).
    The primary constituent elements of critical habitat determined 
necessary for the survival and recovery of these Virgin River fishes 
are water, physical habitat, and biological environment. The desired 
conditions for each of these elements are further discussed below.
    Water--A sufficient quantity and quality of water (i.e., 
temperature, dissolved oxygen, contaminants, nutrients, turbidity, 
etc.) that is delivered to a specific location in accordance with a 
hydrologic regime that is identified for the particular life stage for 
each species. This includes the following:
    1. Water quality characterized by natural seasonally variable 
temperature, turbidity, and conductivity;
    2. hydrologic regime characterized by the duration, magnitude, and 
frequency of flow events capable of forming and maintaining channel and 
instream habitat necessary for particular life stages at certain times 
of the year; and
    3. flood events inundating the floodplain necessary to provide the 
organic matter that provides or supports the nutrient and food sources 
for the listed fishes.
    Physical Habitat--Areas of the Virgin River that are inhabited or 
potentially habitable by a particular life stage for each species, for 
use in spawning, nursing, feeding, and rearing, or corridors between 
such areas:
    1. River channels, side channels, secondary channels, backwaters, 
and springs, and other areas which provide access to these habitats;
    2. areas inhabited by adult and juvenile woundfin include runs and 
pools adjacent to riffles that have sand and sand/gravel substrates;
    3. areas inhabited by juvenile woundfin are generally deeper and 
slower. When turbidity is low, adults also tend to occupy deeper and 
slower habitats;
    4. areas inhabited by woundfin larvae include shoreline margins and 
backwater habitats associated with growths of filamentous algae.
    Biological Environment--Food supply, predation, and competition are 
important elements of the biological environment and are considered 
components of this constituent element. Food supply is a function of 
nutrient supply, productivity, and availability to each life stage of 
the species. Predation and competition, although considered normal 
components of this environment, are out of balance due to nonnative 
fish species in many areas. Fourteen introduced species, including red 
shiner (Cyprinella lutrensis), black bullhead (Ameiurus melas), channel 
catfish (Ictalurus punctatus), and largemouth bass (Micropterus 
salmoides), compete with or prey upon the listed fishes. Of these, the 
red shiner is the most numerous and has been the most problematic for 
the listed fishes. Red shiners compete for food and available habitats 
and are known to prey on the eggs and early life stages of the listed 
fishes. Components of this constituent element include the following:
    1. Seasonally flooded areas that contribute to the biological 
productivity of the river system by producing allochthonous (humus, 
silt, organic detritus, colloidal matter, and plants and animals 
produced outside the river and brought into the river) organic matter 
which provides and supports much of the food base of the listed fishes; 
and
    2. few or no predatory or competitive nonnative species in occupied 
Virgin River fishes' habitats or potential reestablishment sites.

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[GRAPHIC] [TIFF OMITTED] TR26JA00.001



[[Page 4156]]


    Dated: January 18, 2000.
Stephen C. Saunders,
Acting Assistant Secretary for Fish and Wildlife and Parks.
[FR Doc. 00-1746 Filed 1-25-00; 8:45 am]
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