Endangered and Threatened Wildlife and Plants; Determination of Critical Habitat for the Colorado River Endangered Fishes: Razorback Sucker, Colorado Squawfish, Humpback Chub, and Bonytail Chub

SUMMARY: The Fish and Wildlife Service designates critical habitat for

four species of endemic Colorado River Basin fishes: Razorback sucker

(Xyrauchen texanus), Colorado squawfish (Ptychocheilus lucius),

humpback chub (Gila cypha), and bonytail chub (Gila elegans). These

species are listed as endangered under the Endangered Species Act of

1973, as amended. The critical habitat designated is located primarily

on Federal land and, to a lesser extent, on tribal, State, and private

lands. The designation provides additional protection required under

section 7 of the Act with regard to activities that require Federal

agency action. The Service designates 3,168 km (1,980 mi) of critical

habitat for the four Colorado River endangered fishes in portions of

Colorado, Utah, New Mexico, Arizona, Nevada, and California. The areas

designated for each species also overlap some areas designated for the

other species.

EFFECTIVE DATE: April 20, 1994.

ADDRESSES: The complete file for this rule is available for public

inspection, by appointment, during normal business hours at the office

of the Field Supervisor, Ecological Services, U.S. Fish and Wildlife

Service, 2060 Administration Building, 1745 West 1700 South, Salt Lake

City, Utah 84104.

FOR FURTHER INFORMATION CONTACT: Reed E. Harris, Field Supervisor, at

the above address, telephone 801/975-3630.

SUPPLEMENTARY INFORMATION:

Background

The four endangered fishes are endemic to the Colorado River Basin

(Basin), which consists of portions of seven Western States. The Basin

drains approximately 627,000 km\2\ (242,000 mi\2\) within the United

States and has been politically divided into an Upper and Lower Basin.

The Upper Basin consists of portions of the States of Colorado, New

Mexico, Utah, and Wyoming. The Lower Basin consists of portions of the

States of Arizona, California, and Nevada. An additional 5,000 km\2\

(2,000 mi\2\) of the Basin lies within Mexico.

Historically, the native fish fauna of the Basin was dominated by

the minnow (cyprinids) and sucker (catostomids) families (Minckley et

al. 1986). The four species of concern, the razorback sucker (Xyrauchen

texanus), Colorado squawfish (Ptychocheilus lucius), humpback chub

(Gila cypha), and bonytail chub (Gila elegans) are listed as endangered

under the Endangered Species Act (Act) of 1973, as amended (16 U.S.C.

1531 et seq.). These fishes are threatened with extinction due to the

cumulative effects of environmental impacts that have resulted in

habitat loss (including alterations to natural flows and changes to

temperature and sediment regimes), proliferation of nonnative

introduced fish, and other man-induced disturbances (Miller 1961;

Minckley 1973; U.S. Fish and Wildlife Service [USFWS] 1987; Carlson and

Muth 1989).

Natural Colorado squawfish populations survive only in the Upper

Basin, where their numbers are relatively high only in the Green River

Basin of Utah and Colorado (compared with other rivers in the Upper

Basin) (Tyus 1991). Razorback sucker and bonytail chub populations

throughout the Basin consist predominately of old adult fish.

Populations persist primarily because of the longevity of these species

(USFWS 1990a; Minckley et al. 1991), although some experimental and

augmentation programs have stocked fish in the Basin. Humpback chub

populations in the Little Colorado River, Black Rocks, and Westwater

Canyon in the Colorado River appear relatively stable in number of

fish, but declines have occurred in other locations (USFWS 1990b).

The historical ranges of the four endangered fishes have been

fragmented by construction of dams and water diversions throughout the

Basin (Carlson and Muth 1989). The Fish and Wildlife Service (Service)

believes that it is important to the survival and recovery of these

species to maintain and reestablish populations in geographically

distinct areas within their historic range that provide varying

thermal, chemical, geological, and physical parameters required for

maintenance of genomes.

Conservation of these four species will require the identification

and management of water resources and habitat components that are

considered important to any fish species, such as spawning areas,

nursery grounds, and interactions with predators and competitors.

However, because the four endangered fishes are present in such low

numbers, basic life history and habitat use information has been

difficult to obtain. Changes to the historical Colorado River Basin

ecosystem that have resulted in a lack of reproduction and/or

recruitment have been hypothesized as factors in their endangerment

(USFWS 1990a, 1990b, 1991; Minckley et al. 1991). In this case, not

only would a lack of successful recruitment lead to small numbers of

fish, but over time, remnant stocks may lose genetic diversity.

Ultimately, extinction could result because the loss of genetic

diversity may make populations less able to adjust to environmental

change.

Habitats and Status of Endangered Fish

Affected Environment

The four Colorado River endangered fishes evolved in the Colorado

River Basin (Basin) and were adapted to the natural environment that

existed prior to the beginning of large-scale water development and

introduction of nonnative species. This natural environment was

characterized by highly fluctuating seasonal and annual flows,

distinctly different habitat types (i.e., whitewater, lower gradient

and meandering main channels, off-channel backwaters, and others) and

varying water quality (i.e., sediment load, temperature, salinity,

etc.). Recent population declines and disappearances of endemic Basin

fish species from much of their former range have been associated with

the onset of rapid and widespread anthropogenic changes to the natural

environment. The cumulative environmental impact of these changes has

resulted in alteration of the physical and biological characteristics

of many rivers in the Basin. These impacts presumably occurred so

rapidly that the fish could not adapt to them (Carlson and Muth 1989).

Dams and diversions have fragmented former fish habitat and restricted

fish movement. As a result, genetic interchange (emigration and

immigration of individuals) between some fish populations is no longer

possible. High flood flows were once normal in the Basin and provided

food and nutrient exchange between river channels and shallow-water

flood plain habitats. These high flows are now controlled by numerous

dams. As a result of these dams, major changes also have occurred in

water quality, quantity, temperature, sediment load and nutrient

transport, and other characteristics of the aquatic environment

(Carlson and Muth 1989). The altered river conditions that have

resulted now provide suitable habitats for introduced, nonnative fish.

Some of these nonnative fish species have flourished in the Basin

(Minckley et al. 1982; Tyus et al. 1982; Carlson and Muth 1989). These

physical and biological changes have impacted the river environment to

the extent that no completely unaltered habitat remains in the Basin

for the four Colorado River endangered fish species.

Razorback Sucker

This species once was abundant and widely distributed in rivers of

the Basin (Jordan and Evermann 1896; Minckley 1973). In the Lower

Basin, the razorback sucker remains in the Colorado River from the

Grand Canyon to near the border with Mexico. With the exception of the

relatively large stock of razorback suckers remaining in Lake Mohave

(an estimated 25,000 individuals), these populations are small and

recruitment is virtually nonexistent (Minckley et al. 1991). The

formerly large Lower Basin populations have been virtually extirpated

from other riverine environments (Minckley et al. 1991). In the Upper

Basin, this species remains in the lower Yampa and Green Rivers,

mainstream Colorado River, and lower San Juan River (Tyus et al. 1982;

Minckley et al. 1991; Platania et al. 1991); however, there is little

indication of recruitment in these remnant stocks. The largest extant

riverine population occurs in the upper Green River Basin. It consisted

of only about 1,000 fish in 1989 (Lanigan and Tyus 1989); recent

information suggests that this population may have declined to less

than 500 fish (USFWS unpublished data). In the absence of conservation

efforts, it is presumed that all wild populations in the Basin would

soon be lost as old fish die without sufficient natural recruitment.

Reproduction and habitat use of razorback suckers has been studied

in Lower Basin reservoirs, especially in Lake Mohave. Fish reproduction

has been visually observed along reservoir shorelines for many years.

The fish spawn over mixed substrates that range from silt to cobble and

at water temperatures ranging from 10.5 to 21 deg. C (51 to 70 deg. F)

(reviewed by Minckley et al. 1991).

Habitat use and spawning behavior of adult razorback suckers in

riverine habitats has been studied by radiotelemetry in the Green River

Basin (Tyus and Karp 1990) and in the upper Colorado River (Osmundson

and Kaeding 1989). Fish in the Green River Basin spawn in the spring

with rising water levels and increasing temperatures. Razorback suckers

move into flooded areas in early spring and begin spawning migrations

to specific locations as they become reproductively active, and

spawning occurs over rocky runs and gravel bars (Tyus and Karp 1990).

In nonreproductive periods, adult razorback suckers occupy a

variety of habitat types, including impounded and riverine areas,

eddies, backwaters, gravel pits, flooded bottoms, flooded mouths of

tributary streams, slow runs, sandy riffles, and others (reviewed by

Minckley et al. 1991). Summer habitats used include deeper eddies,

backwaters, holes, and midchannel sandbars (Osmundson and Kaeding 1989;

Tyus and Karp 1990; Minckley et al. 1991). During winter, adult

razorback suckers use main channel habitats that are similar to those

used during other times of the year, including eddies, slow runs,

riffles, and slackwaters (Osmundson and Kaeding 1989; Valdez and

Masslich 1989; Tyus and Karp 1990).

Habitats used by young razorback suckers have not been fully

described because of the low number of young fish present in the Basin.

However, most studies indicate that the larvae prefer shallow, littoral

zones for a few weeks after hatching, then disperse to deeper water

areas (reviewed by Minckley et al. 1991). Laboratory studies indicated

that in a riverine environment, the larvae enter stream drift and are

transported downstream (Paulin et al. 1989).

Based on available data, Tyus and Karp (1989) and Osmundson and

Kaeding (1989) considered that cumulative environmental impacts from

interactions with nonnative fish, high winter flows, reduced high

spring flows, seasonal changes in river temperatures, and lack of

inundated shorelines and bottom lands are factors that potentially

limit the survival, successful reproduction, and recruitment of this

species.

Colorado Squawfish

This species is the only living representative of the genus

Ptychocheilus endemic to the Basin. Fossils from the Mid-Pliocene epoch

(about 6 million years ago) indicate that early Ptychocheilus had

physical characteristics that were similar to modern forms. Native

populations of the Colorado squawfish are now restricted to the Upper

Basin in Wyoming, Colorado, Utah, and New Mexico. Colorado squawfish

populations have been extirpated from the Lower Basin.

Colorado squawfish spawning has been documented in canyons in the

Yampa and Green Rivers (Tyus 1991). This reproduction is associated

with declining flows in June, July, or August and average water

temperatures ranging from 22 to 25 deg.C (72 to 77 deg.F) depending

on annual hydrology. River mile 130 on the Colorado River, near the

Colorado-Utah State line, also has been identified as a spawning site,

and radio-tagged adults have moved to a specific 0.2 km (0.1 mi) area

in four different years (Osmundson and Kaeding 1989; USFWS unpublished

data 1992-1993). In the mainstream Colorado River, McAda and Kaeding

(1991) stated that spawning occurs at many locations. They also

suggested that Colorado squawfish spawning in the Colorado River may

have been adversely impacted by construction of mainstream dams and a

48 percent reduction in peak discharge. On the San Juan River, a

spawning reach has been identified between river mile 133.4 and 129.8,

near the confluence of the Mancos River (Ryden and Pfeifer 1993).

After spawning, adult Colorado squawfish utilize a variety of

riverine habitats, including eddies, backwaters, shorelines, and others

(Tyus 1990). During winter, adult Colorado squawfish use backwaters,

runs, pools, and eddies, but are most common in shallow, ice-covered

shoreline areas (Osmundson and Kaeding 1989; Wick and Hawkins 1989). In

spring and early summer, adult squawfish use shorelines and lowlands

inundated during typical spring flooding. This natural lowland

inundation is viewed as important for their general health and

reproductive conditioning (Osmundson and Kaeding 1989; Tyus 1990). Use

of these habitats presumably mitigates some of the effects of winter

stress, and aids in providing energy reserves required for migration

and spawning. Migration is an important component in the reproductive

cycle of Colorado squawfish. Tyus (1990) hypothesized that migration

cues, such as high spring flows, increasing river temperatures, and

chemical inputs from flooded lands and springs, may be important to

successful reproduction.

In the Green River Basin, larval Colorado squawfish emerge from

spawning substrates and enter the stream drift as young fry (Haynes et

al. 1989). The larval fish are actively or passively transported

downstream for about 6 days, traveling an average distance of 160 km

(100 mi) to reach nursery areas in lower gradient reaches (Tyus and

Haines 1991). These areas are nutrient-rich habitats that consist of

ephemeral along-shore embayments that develop as spring flows decline.

Humpback Chub

Remains of humpback chub have been found in archaeological sites

dated to about 4000 B.C. (USFWS 1990b). This Colorado River native fish

was not described as a species until 1946 (Miller 1946). This has been

attributed to its presently restricted distribution in remote, white

water canyons (USFWS 1990b). The historical abundance and distribution

of the species is not well known. In the Lower Basin, the humpback chub

occurs in the Little Colorado and Colorado Rivers in the Grand Canyon.

This population is the largest remaining in the Basin. In the Upper

Basin, humpback chub are found in the Black Rocks/Westwater Canyon and

Cataract Canyon of the Colorado River, Desolation and Gray Canyons of

the Green River, and Yampa and Whirlpool Canyons in Dinosaur National

Monument, Green and Yampa Rivers (USFWS 1990b).

Humpback chub in reproductive condition are usually captured in

May, June, or July, depending on location. Spawning occurs soon after

the highest spring flows when water temperatures approach 20 deg. C

(68 deg. F) (Karp and Tyus 1990; USFWS 1990b). The importance of spring

flows and proper temperatures for humpback chub is stressed by Kaeding

and Zimmerman (1983), who implicated flow reductions and low water

temperatures in the Grand Canyon as factors curtailing successful

spawning of the fish and increasing competition from other species.

Populations of humpback chub are found in river canyons, where they

utilize a variety of habitats, including pools, riffles, and eddies.

Most of the existing information on habitat preferences has been

obtained from adult fish in the Little Colorado River, the Grand

Canyon, and the Black Rocks of the Colorado River (Holden and Stalnaker

1975; Kaeding and Zimmerman 1983; Kaeding et al. 1990). In these

locations, the fish are found associated with boulder-strewn canyons,

travertine dams, pools, and eddies. Some habitat-use data also are

available from the Yampa River Canyon where the fish occupy similar

habitats and also use rocky runs, riffles, rapids, and shoreline eddies

(Karp and Tyus 1990). This diversity in habitat use suggests that the

adult fish are adapted to a variety of habitats, and studies of tagged

fish indicated that they move between habitats, presumably in response

to seasonal habitat changes and life history needs (Kaeding and

Zimmerman 1983; Karp and Tyus 1990). Reduced spring peak flows,

availability of shoreline eddy and deep canyon habitats, and

competition and predation by nonnative fish were reported as potential

limiting factors for humpback chub in the Yampa River (Tyus and Karp

1989). The impact of hybridization with other species is currently

being evaluated.

Bonytail Chub

The bonytail chub (also known as the bonytail) is the rarest native

fish in the Basin. Historically reported as widespread and abundant in

rivers throughout the Basin (Jordan and Evermann 1896), its populations

have been greatly reduced. The fish is presently represented in the

wild by a low number of old fish (i.e., ages of 40 years or more), and

recruitment is virtually nonexistent. In the Lower Basin, a small

population persists in the Colorado River in Lake Mohave, and there are

recent records from Lake Havasu (USFWS 1990a). In the Upper Basin,

recent captures have been from Dinosaur National Monument on the Yampa

River, Desolation and Gray Canyons on the Green River, and Black Rocks

and Cataract Canyon on the Colorado River (Kaeding et al. 1986; Tyus et

al. 1987; Valdez 1990; USFWS 1990a).

The bonytail chub is adapted to mainstream rivers, where it has

been observed in pools and eddies (Minckley 1973; Vanicek 1967). In

reservoirs, the fish occupies a variety of habitat types (Minckley

1973). In Lake Mohave, Wagner (1955) observed the fish in eddy

habitats. Spawning requirements have never been documented in a river,

but Vanicek and Kramer (1969) reported that spawning occurred in June

and July at water temperatures of about 18 deg. C (64 deg. F). The

available data suggest that habitats required for conservation of the

bonytail chub include, river channels, and flooded, ponded, or

inundated riverine habitats that would be suitable for adults and

young, especially if competition from nonnative fishes is reduced

(USFWS 1990a).

Previous Federal Actions

Listing Chronology

The Colorado squawfish and humpback chub were listed as endangered

species on March 11, 1967 (32 FR 4001) and the bonytail chub was listed

as endangered on April 23, 1980 (45 FR 27713). Critical habitat for

these species was not designated at the time of their listing. On May

16, 1975, the Service published a notice of its intent to determine

critical habitat for the Colorado squawfish and the humpback chub, and

other species (40 FR 21499). On September 14, 1978, the Service

proposed 1,002 km (623 mi) of the Colorado, Green, Gunnison, and Yampa

Rivers as critical habitat for the Colorado squawfish (43 FR 41060).

The proposal was for 1,002 km (623 mi) of the Colorado, Green,

Gunnison, and Yampa Rivers. This proposal was later withdrawn (44 FR

12382; March 6, 1979) to comply with the 1978 amendments to the Act (16

U.S.C. 1531 et seq.).

The razorback sucker was first proposed for listing as a threatened

species on April 24, 1978 (43 FR 17375). The proposal was withdrawn on

May 27, 1980 (45 FR 35410), to comply with provisions of the 1978

amendments to the Act. These provisions required the Service to include

consideration of designating critical habitat in the listing of

species, to complete the listing process within 2 years from the date

of the proposed rule, or withdraw the proposal from further

consideration. The Service did not complete the listing process within

the 2-year deadline.

On March 15, 1989, the Service received a petition from the Sierra

Club, National Audubon Society, The Wilderness Society, Colorado

Environmental Coalition, Southern Utah Wilderness Alliance, and

Northwest Rivers Alliance to list the razorback sucker as endangered.

The Service made a positive finding in June 1989 and subsequently

published a notice in the Federal Register on August 15, 1989 (54 FR

33586). This notice also stated that the Service was completing a

status review and was seeking additional information until December 15,

1989. A proposed rule to list the razorback sucker as endangered was

published in the Federal Register on May 22, 1990 (55 FR 21154).

The final rule listing the razorback sucker as an endangered

species was published on October 23, 1991 (56 FR 54957), but critical

habitat was not proposed. In the final rule, the Service concluded that

critical habitat was not determinable at the time of listing and

questioned whether it was prudent to designate critical habitat.

On October 30, 1991, the Service received a 60-day notice of intent

to sue from the Sierra Club Legal Defense Fund. The subject of the

notice was the Service's failure to designate critical habitat

concurrent with listing of the razorback sucker pursuant to section

4(b)(6)(c) of the Act. The Sierra Club Legal Defense Fund followed this

with a second notice of intent to sue dated January 30, 1992. At a

meeting on December 6, 1991, the Service concluded that designation of

critical habitat was prudent and determinable and therefore in

compliance with the Act. The Service had no alternative but to

designate critical habitat for the razorback sucker. Because the intent

of the Act is ``* * * to provide a means whereby the ecosystems upon

which endangered species and threatened species depend may be conserved

* * *,'' the Service also decided to propose critical habitat for the

Colorado squawfish, humpback chub, and bonytail chub. The four

endangered Colorado River fish species coexist in the Basin and much of

their habitat overlaps.

On May 7, 1992, the Sierra Club Legal Defense Fund on behalf of the

Colorado Wildlife Federation, Southern Utah Wilderness Alliance, Four

Corners Action Coalition, Colorado Environmental Coalition, Taxpayers

for the Animas River, and Sierra Club filed a lawsuit in the U.S.

District Court (Court), Colorado, against the Service for failure to

designate critical habitat for the razorback sucker. On August 18,

1992, a motion for summary judgment was filed requesting the Court to

order publication of a final rule to designate critical habitat within

90 days. On October 27, 1992, the Court ruled that the Service had

violated the Act by failing to designate critical habitat when the

razorback sucker was listed. The Court ordered the Service to publish a

proposed rule within 90 days designating critical habitat for the

razorback sucker using presently available information, and to publish

a final rule at the earliest time permitted by the Act and its

regulations. To take no action towards designation of critical habitat

would continue to place the Service in violation of the Act and was not

a feasible alternative.

The Service published the proposed rule to designate critical

habitat on January 29, 1993 (58 FR 6578). At that time, the Service had

not completed an economic analysis or a biological support document.

The Service published the Draft Biological Support Document for public

review on September 15, 1993, and reopened the public comment period

(58 FR 48351). On September 21, 1993, the Court held a hearing on the

Sierra Club Legal Defense Fund ``Motion For A Timetable For Publication

Of Final Rule'' on the designation of critical habitat. On November 19,

1993, the Court directed the Service (1) not to submit an interim final

rule, (2) to provide a 60-day comment period for the economic analysis,

(3) to provide notice of the exclusion process and request comments,

and (4) to publish the final rule by March 15, 1994.

Notice of availability of the Economic Analysis, an Overview of the

Proposed Critical Habitat Designation, and a request for public

comments were made in the Federal Register on November 12, 1993 (58 FR

5997), and in a November 9, 1993, letter sent to interested parties.

The public comment period closed on January 11, 1994. On January 18,

1994, the Service conducted the exclusion process, assessing all the

information pertinent to a decision to exclude areas from designation

as critical habitat for economic or other relevant reasons.

Recovery Planning

Recovery plans have been written for three of the four listed

Colorado River fishes. The Colorado Squawfish Recovery Plan was

approved on March 16, 1978, and revised on August 6, 1991 (USFWS 1991).

The Humpback Chub Recovery Plan was approved on August 22, 1979, with a

first revision on May 15, 1984, and a second revision on September 19,

1990 (USFWS 1990b). The Bonytail Chub Recovery Plan was approved on May

16, 1984, with a revised plan approved September 4, 1990 (USFWS 1990a).

Recovery goals contained in these recovery plans have been used in

identifying and evaluating critical habitat for these three species. A

recovery plan for the razorback sucker has not been completed.

Determination of Critical Habitat

Definition of Critical Habitat

``Critical habitat,'' as defined in section 3(5)(A) of the Act,

means: ``(i) the specific areas within the geographical area occupied

by the species at the time it is listed * * *, 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 by the Secretary that such areas are essential for

the conservation of the species.''

The term ``conservation,'' as defined in section 3(3) of the Act,

means: ``* * * 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.'' In the case of critical habitat, conservation represents

the areas required to recover a species to the point of delisting

(i.e., the species is recovered and is removed from the list of

endangered and threatened species). In this context, critical habitat

preserves options for a species' eventual recovery. Section 3(5)(C)

further states that: ``Except in those circumstances determined by the

Secretary, critical habitat shall not include the entire geographical

area which can be occupied by the threatened or endangered species.''

Role of Critical Habitat in Species Conservation

The designation of critical habitat will not, by itself, lead to

recovery but is one of several measures available to contribute to

conservation of a species. Critical habitat helps focus conservation

activities by identifying areas that contain essential habitat features

(primary constituent elements) regardless of whether or not the areas

are currently occupied by the listed species. Such designations alert

Federal agencies, States, the public, and other entities about the

importance of an area for the conservation of a listed species.

Critical habitat also identifies areas that may require special

management or protection. Areas designated as critical habitat receive

protection under section 7 of the Act with regard to actions carried

out, funded, or authorized by a Federal agency that are likely to

adversely modify or destroy critical habitat. Section 7 requires that

Federal agencies consult on their actions that may affect critical

habitat and insure that their actions are not likely to destroy or

adversely modify critical habitat.

Designation of an area as critical habitat only affects Federal

actions that may occur in the area. Designation does not create a

management plan for a listed species. Designation does not

automatically prohibit certain actions, establish numerical population

goals, prescribe specific management actions (inside or outside of

critical habitat), nor does it have a direct effect on habitat not

designated as critical habitat. However, critical habitat may provide

added protection for areas designated and thus assist in achieving

recovery.

Areas Outside of Critical Habitat

Areas outside of critical habitat that contain one or more of the

primary constituent elements may still be important for conservation of

a species. Also, some areas do not contain all of the constituent

elements and may have those missing elements restored in the future.

Such areas also may be important for the long-term recovery of the

species even if they were not designated as critical habitat. Areas not

designated as critical habitat also may be of value in maintaining

ecosystem integrity and supporting other species, indirectly

contributing to recovery of a species.

Areas outside of critical habitat are still subject to section 7

consultation on whether or not an action is likely to jeopardize the

continued existence of a species, and section 9 ``take'' prohibitions

for an action that may affect Colorado River endangered fishes or their

habitat. The Service anticipates that the importance of areas outside

of critical habitat to the conservation of the Colorado River

endangered fishes will be addressed through section 7, section 9, and

section 10 permit processes, the recovery planning process, and other

appropriate State and Federal laws.

Primary Constituent Elements

In determining which areas to designate as critical habitat for a

species, the Service considers those physical and biological attributes

that are essential to species conservation (i.e., constituent

elements). Such physical and biological features are stated in 50 CFR

424.12 and include, but are not limited to, the following items: (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 generally;

(5) Habitats that are protected from disturbance or are

representative of the historical geographical and ecological

distributions of a species.

In addition, the Act stipulates that the areas containing these

elements may require special management considerations or protection.

Detailed descriptions and the biological basis for the constituent

elements were presented in the Draft Biological Support Document

(Maddux et al. 1993). In considering the biological basis for

determining critical habitat, the Service focused on the primary

physical and biological elements essential to the conservation of the

species. The primary constituent elements are interrelated in the life

history of these species. This relationship was a prime consideration

in the designation of critical habitat. The Service is required to list

the known primary constituent elements together with a description of

any critical habitat that is designated.

The primary constituent elements determined necessary for survival

and recovery of the four Colorado River endangered fishes include, but

are not limited to:

Water

This includes a quantity of water of sufficient quality (i.e.,

temperature, dissolved oxygen, lack of contaminants, nutrients,

turbidity, etc.) that is delivered to a specific location in accordance

with a hydrologic regime that is required for the particular life stage

for each species.

Physical Habitat

This includes areas of the Colorado River system that are inhabited

or potentially habitable by fish for use in spawning, nursery, feeding,

and rearing, or corridors between these areas. In addition to river

channels, these areas also include bottom lands, side channels,

secondary channels, oxbows, backwaters, and other areas in the 100-year

flood plain, which when inundated provide spawning, nursery, feeding

and rearing habitats, or access to these habitats.

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 introduced nonnative fish

species in many areas.

Additional Selection Criteria for the Razorback Sucker

Because a recovery plan for the razorback sucker has not been

completed, additional selection criteria were developed to assist the

Service in making a determination of areas to propose as critical

habitat. Previous Service findings, published and unpublished

literature sources, and discussions with individual members of the

Colorado River Fishes Recovery Team were utilized to develop the

constituent elements and additional selection criteria.

Adult razorback suckers have displayed a degree of versatility in

their ability to survive and spawn in different habitats. However,

razorback sucker populations continue to decline and are considered

below the survival level. Thus, as versatile as the adult life stage of

razorback sucker appears to be in selecting spawning habitat, there has

been little or no recruitment of young to the adult population.

Therefore, special consideration was given to habitats required for

reproduction and recruitment.

The following selection considerations were used by the Service to

help determine areas necessary for survival and recovery of the

razorback sucker.

1. Presence of known or suspected wild spawning populations,

although recruitment may be limited or nonexistent.

2. Areas where juvenile razorback suckers have been collected or

which could provide suitable nursery habitat (backwaters, flooded

bottom lands, or coves).

3. Areas presently occupied or that were historically occupied that

are considered necessary for recovery and that have the potential for

reestablishment of razorback suckers.

4. Areas and water required to maintain rangewide fish distribution

and diversity under a variety of physical, chemical, and biological

conditions.

5. Areas that need special management or protection to insure

razorback survival and recovery. These areas once met the habitat needs

of the razorback sucker and may be recoverable with additional

protection and management.

The primary constituent elements were identified throughout the

historical range of the Colorado River endangered fishes. In addition,

the five selection considerations described above also were used to

evaluate potential razorback sucker critical habitat areas. The

critical habitat designations were based on the primary constituent

elements, published and unpublished sources of information, Service

reports and other findings, recovery plans (for Colorado squawfish,

humpback chub, and bonytail chub), the additional selection

considerations, and the Service's preliminary recovery goals for the

razorback sucker.

Adjustments to Boundaries

The 100-year flood plain is generally included as part of the

critical habitat designation; however, only those portions of the flood

plain that contain the constituent elements are considered part of

critical habitat. Specific areas in the flood plain must be evaluated

on a case-by-case basis to determine if the areas constitute critical

habitat. The Service stresses that, although critical habitat may only

be seasonally occupied by the fish, such habitat remains important for

their conservation. Protection of such seasonally occupied habitats

contributes to the conservation of the species.

As a result of obtaining additional biological information and

review of comments received during the public comment period, the

Service has determined that some areas are not required for the

survival and recovery of the fishes because they do not contain the

constituent elements, meet the additional selection criteria, or are

not in historical habitat. In addition, other areas may contain

constituent elements but may contribute little to the prospect of

recovery for one or more of the four fishes. Some of these areas are

within sections of designated critical habitat and will be evaluated on

a case-by-case basis. Five stream sections are separable and have been

removed from consideration as part of critical habitat because of a

lack of biological importance. These five areas are:

Davis Dam to the upstream end of Topock Marsh on the

mainstem Colorado River (AZ, CA, NV) (bonytail chub)

Bonita and Eagle Creeks, tributaries to the Gila River

(AZ) (razorback sucker)

Cherry and Canyon Creeks, tributaries to the Salt River

(AZ) (razorback sucker)

Sycamore, Oak, and West Clear Creeks, tributaries to the

Verde River (AZ) (razorback sucker)

The Verde River from Sullivan Lake to Perkinsville (AZ)

(razorback sucker)

The Service reiterates that any or all of these sections could

contribute to the recovery of one or more of the fishes; however, they

do not provide a primary recovery area and are considered only

marginally important. The Service also notes that some of these areas

may not have been historical habitat for the razorback sucker, a

further indication that these areas may have only limited value in the

recovery of these fishes.

Economic Impacts

Introduction

Section 4(b)(2) of the Act directs the Secretary of the Interior

(Secretary) to consider economic and other relevant impacts in

determining whether to exclude proposed areas from the final

designation of critical habitat. The Service, as delegated by the

Secretary, may exclude areas from critical habitat designation when the

benefits of exclusion outweigh the benefits of inclusion, provided that

exclusion will not result in extinction of a species. An economic

analysis (Brookshire et al. 1994) was conducted on the consequences of

this action (critical habitat designation).

The study region for the economic analysis includes the seven

States of the Basin: Arizona, California, Colorado, New Mexico, Nevada,

Utah, and Wyoming. The timeframe chosen for the study, 1995 through

2020, encompasses the time period projected for the recovery of the

endangered fishes.

Linkages between the biological requirements for recovering the

endangered fishes and economic activities in the region formed the

basis for the economic analysis. As an index of these biological

requirements, adjustments made in the operations of Federal reservoirs

in the Basin and/or mitigation of nonflow related activities along the

river's 100-year flood plain were included. The effects of recovery

efforts on future water depletions in the Basin also were taken into

consideration. The direct and indirect impacts of these possible

changes on current and prospective economic activities were then

estimated for each State, the region, and the national economy.

It is impossible to predict the outcome of future section 7

consultations involving endangered fishes in the Basin. If the Upper

Basin and San Juan Recovery Implementation Programs (RIP) do not show

sufficient and timely progress in recovering the endangered fishes,

some planned water developments may be modified, scaled back, delayed,

or foregone. This assumption provides an upper bound on the potential

magnitude of economic impacts associated with the critical habitat

designation. If the RIP's are successful in achieving their objectives,

many of the negative economic impacts can be avoided.

Economic Modeling

Two types of economic effects are of interest when considering the

economic impacts of critical habitat designations: regional economic

impacts and national economic efficiency impacts. Regional economic

impacts refer to the direct and indirect impacts of the critical

habitat designations on specific geographic regions, such as States or

other subregions of the country.

Regional economic impacts were analyzed using input-output (I-O)

models that organize the basic accounting relationships that describe

the production sector of the economy (Brookshire et al. 1993). The I-O

method is based on the assumption that all sectors of the economy are

related, and the production of a good or service can be described by a

recipe whose ingredients are the outputs from other sectors of the

economy. The primary inputs are labor, capital, and other raw

resources. Through its multiplier analysis, the I-O model is capable of

generating estimates of the changes in output for economic sectors,

changes in employment, and changes in income due to the critical

habitat designation. The models report total impacts resulting from

interactions among the sectors of the economy.

National economic efficiency impacts refer to the overall net

impacts on the national economy after the effects of interregional

transfers have been accounted for. The goal of a national efficiency

analysis is to determine whether an action would have an overall

positive or negative impact on the national economy.

National economic efficiency impacts were analyzed in this study

using a Computable General Equilibrium (CGE) model. The CGE model

captures the economic interactions of consumers, the production

sectors, and the government sectors. The CGE model also analyzes

resource reallocations (e.g., changes in river flows as represented by

increased or decreased hydroelectric generation) in a manner such that

the net effects, not just the total effects, are calculated. Given this

capability, the CGE model is able to estimate net national efficiency

impacts.

Modeling Approach

A separate I-O model was developed for each State, and focused on

the direct and indirect impacts generated by the critical habitat

designation (Brookshire et al. 1993). In most cases, impacts in a given

State generated impacts in neighboring States. Thus, it was necessary

to investigate potential offsetting impacts. As a result, an I-O model

was constructed that investigated the impacts of the entire region (all

seven States). In addition to the State and regional I-O models, a CGE

model was developed for the economies of the seven-State area and the

rest of the United States. This model provided a comprehensive

aggregate assessment of the national economic efficiency impacts.

Economic activity for the models was estimated using Impact

Analysis for Planning (IMPLAN) 1982 data sets that were updated and

projected through the year 2020, using data from the Bureau of Economic

Analysis of the U.S. Department of Commerce. The IMPLAN data set

contains 528 economic sectors that were aggregated to 20 sectors

(Brookshire et al. 1994).

Without Fish and With Fish Scenarios

Two scenarios were used to evaluate economic activities associated

with the critical habitat designation (Brookshire et al. 1994). The

``without fish'' economic scenario consisted of projections of the

level of economic activities that would be observed over the study

period if no action was taken to recover the endangered fishes. The

``with fish'' scenario was constructed by analyzing potential changes

in economic activity that may occur due to the critical habitat

designations and/or other protection and recovery efforts for

endangered fish.

Economic Setting

Economic Output

Economic output measures the value of all goods and services

produced and/or consumed in a regional economy. The seven State Basin

region generates about $1.3 trillion annually in economic output. This

output is dominated by the combined manufacturing and the finance,

insurance, and real estate sectors, which produce 18.4 percent and 14.9

percent of total output, respectively. The recreation services sector

produces 7.7 percent of the total output and the combined agricultural

sectors are responsible for 3.0 percent of the total output (Brookshire

et al. 1993).

Employment

Approximately 22.0 million people are employed in the Basin

economy. The largest employment sectors within the Basin States are the

public sector (16.9 percent of total employment), and the combined

manufacturing sector (15.4 percent of total employment). The recreation

services sector is also a very significant part of total employment at

10.5 percent. Combined agricultural employment is approximately 4.3

percent of total employment (Brookshire et al. 1993).

State and Regional Economic Impacts

Three conclusions were obtained from the economic analysis (Table

1): First, regional economic impacts associated with critical habitat

designation are positive for the Basin. Second, the State-level impacts

are not distributed evenly over States in the Basin. Finally, the

percent deviation in the economy from the ``without fish'' scenario is

small.

Table 1.--Annualized Impacts ($1991 Millions) of Critical Habitat Designation in Each State and the Colorado

River Basin. Parentheses () = Percent Change in the State and Regional Economies Due to Designation. (After

Brookshire et al. 1994)

----------------------------------------------------------------------------------------------------------------

Indirect

Output (% Earning (% business Personal

State change) change) taxes (% income taxes

change) (% change)

----------------------------------------------------------------------------------------------------------------

Arizona............................................. -1.049

(.0008) -0.201

(.0004) -0.048

(.0006) -0.050

(.0004)

California.......................................... +16.751

(.0013) +2.880

(.0007) +0.521

(.0008) +0.720

(.0007)

Colorado............................................ -0.848

(.0006) +0.850

(.0020) -0.111

(.0020) +0.213

(.0020)

Nevada.............................................. +7.014

(.0148) +3.369

(.0164) +0.582

(.0182) +0.842

(.0164)

New Mexico.......................................... -12.273

(.0279) -1.511

(.0110) -0.586

(.0204) -0.378

(.0110)

Utah................................................ -3.628

(.0060) -0.718

(.0039) -0.281

(.0090) -0.180

(.0040)

Wyoming............................................. -0.359

(.0020) -0.048

(.0008) -0.023

(.0020) -0.012

(.0008)

Basin............................................... +6.470

(.0003) +3.704

(.0006) +0.136

(.0002) +1.049

(.0006)

----------------------------------------------------------------------------------------------------------------

The projected impacts on the economies of various States ranged

from about -$12.273 million in New Mexico to about +$16.751 million in

California measured as annualized values (Table 1). However, projected

negative impacts that could occur in the various State economies were

so small when compared to the base economies that they are probably

nonexistent, ranging from 0.0008 percent in Arizona to 0.0279 percent

in New Mexico. Some States could experience small but positive impacts

(e.g., California and Nevada).

Impacts on earnings, indirect business taxes, and personal income

taxes are organized in the same way as those for output (Table 1). The

conclusions expressed for output hold also for the earnings, indirect

business taxes, and personal income taxes impacts (Brookshire et al.

1994).

Employment

Table 2 presents State and regional incremental impacts on

employment over the 25-year period of the study. The values in the

table represent the deviation in employment, measured as jobs, between

the without fish and with fish scenarios. As with other aspects of the

economy, employment impacts are both positive and negative both across

States and over time. For New Mexico, the employment impact is

approximately 2 jobs foregone in 1995 and this figure rises to 613 jobs

foregone by the year 2020. On the other hand, for California there is a

gain of approximately 20 jobs in 1995 and this positive impact

increases to a projected 1,162 jobs by 2020. For the Basin as a whole,

the employment impacts are positive through the study period. In 1995,

the projected gain is approximately 60 jobs. By 2020, the gains in

employment are projected to be approximately 393 jobs.

Table 2.-- Impacts of the Critical Habitat Designation on Employment in Each State and the Colorado River Basin.

Employment Impacts Represent Jobs Foregone or Gained in the Future Through the Year 2020. (After Brookshire et

al. 1994)

----------------------------------------------------------------------------------------------------------------

State 1995 2000 2005 2010 2015 2020

----------------------------------------------------------------------------------------------------------------

Arizona......................................... -1.85 -4.68 -7.77 -12.08 -18.86 -25.83

California...................................... +19.99 +92.57 +258.48 +475.86 +781.18 +1161.93

Colorado........................................ +8.91 +5.16 -6.93 -19.69 -36.86 -55.60

Nevada.......................................... +34.86 +71.52 +108.03 +143.22 +177.25 +208.69

New Mexico...................................... -2.17 -27.98 -110.71 -239.60 -415.21 -612.64

Utah............................................ -10.91 -22.30 -34.56 -47.71 -61.06 -74.13

Wyoming......................................... -0.40 -1.40 -2.41 -3.45 -4.35 -5.22

Colorado River Basin............................ +59.94 +116.15 +178.70 +230.02 +294.76 +392.67

----------------------------------------------------------------------------------------------------------------

National Economic Impacts

The results below are from the Computable General Equilibrium model

and represent economic output for the Basin (Table 3). Although the

projected national economic impacts were positive for all variables,

there is almost no change in the regional economy.

Table 3.--Results of Computable General Equilibrium Model for the

Colorado River Basin. (After Brookshire et al. 1994)

------------------------------------------------------------------------

Percent

change

Variable Economic impact in

economy

------------------------------------------------------------------------

Regional Product........................ +$7.92 million...... 0.0013

Employment.............................. +710 jobs........... 0.0047

Earnings................................ +$6.62 million...... 0.0017

Govt Revenue............................ +$3.20 million...... 0.0016

------------------------------------------------------------------------

Exclusion Process

Background

Pursuant to section 4(b)(2) of the Act, critical habitat is

designated by using the best scientific data available, and in full

consideration of economic and other impacts of designation. The

determination on whether to exclude a reach or portion of a reach

considers: (1) The benefits of including that reach, (2) the benefits

of excluding a reach, and (3) the effect of that reach, or the

cumulative effect of excluding more than one reach, on the probability

of species extinction. If the exclusion of a river reach or portion of

a reach would result in the eventual extinction of a species, the

exclusion is prohibited under the Act.

Exclusion of an area as critical habitat would eliminate the

protection provided under the destruction or adverse modification

provision of section 7 for critical habitat. However, it would not

remove the need to comply with other requirements of the Act for that

area, such as the ``likely to jeopardize'' prohibition of section 7

consultation (for Federal actions) and section 9 (take). Section 7

consultation requirements apply to Federal actions regardless of

whether or not critical habitat is designated for a particular area.

The Service determined whether the benefits of inclusion of

critical habitat areas would outweigh the benefits of their exclusion,

by using five sequential steps:

Step 1--Identify areas that meet the definition of critical habitat

in section 3(5) of the Act and that are considered essential to the

conservation of the species. This was accomplished, and the areas

needed for conservation were published in the proposed rule to

designate critical habitat on January 29, 1993 (58 FR 6578).

Justifications for these areas were presented in the Draft Biological

Support Document, which was made available to the public on September

15, 1993 (58 FR 48351).

Step 2--Conduct an economic analysis to determine the anticipated

economic consequences of designating areas as critical habitat. A draft

report on the economic analysis was completed and made available to the

public for comment on November 12, 1993 (58 FR 59979).

Step 3--Develop economic criteria or thresholds to help identify

those areas that would be significantly affected by the critical

habitat designation. Comments were requested from the public to aid in

developing the criteria (November 12, 1993; 58 FR 59979).

Step 4--Compile the biological information that should be

considered to determine whether excluding an area would result in

extinction. Primary consideration was given to information contained in

published recovery plans. The Service determined whether exclusion of

an area will result in the extinction of a species.

Step 5--Conduct the exclusion process. The Service has evaluated

which areas, if any, should be excluded due to economic or other

relevant impacts. Prior to this evaluation, economic criteria in the

form of thresholds (Step 3) were developed to provide a method by which

the severity of economic impacts could be assessed. Those areas that

exhibited economic impacts above the thresholds were then examined to

determine if the biological threshold of extinction would be exceeded

(Step 4) if the specific area in question was dropped from

consideration as critical habitat.

Benefits and Costs of Designation

A public sector analysis examined the allocation of scarce

resources regarding economic efficiency and distribution or equity

(Brookshire et al. 1993, 1994). The efficiency criterion addressed

whether designating areas as critical habitat produces greater net

benefits than costs. The equity criterion looks at the resulting

distribution of gains and losses. The Act requires the Service to

protect threatened and endangered species for all citizens, now and in

the future. This mandate falls under the national economic efficiency

concern, where policy adjustments seek to minimize economic efficiency

losses for society while preserving endangered species.

The Service does not have a mandated requirement to conduct an

efficiency-based benefit-cost analysis when carrying out its resource

protection activities. This is particularly true for species listing

activities under the Act, where economic considerations are explicitly

prohibited. During critical habitat designation, however, consideration

of benefits and costs can occur when ``economic and other relevant

impacts'' are specifically included as part of the process of final

determination.

The economic analysis (Brookshire et al. 1994) only addressed

market-related benefits and costs. No attempt was made to estimate

nonmarket values associated with the preservation of the endangered

fishes. However, the Service recognizes that the benefits of

preservation are positive. The extant literature addressing the value

of wildlife resources documents positive benefits for consumptive and

nonconsumptive uses of wildlife species. The legislative history of the

Act indicates that Congress believed that the ``worth'' or value of a

species is incalculable and invaluable. This is supported by the

Supreme Court interpretation of the Act in TVA v. Hill, 437 U.S. 153,

178 (1978). This concept is applicable to the Basin as it represents

one of the most distinctive collections of flora and fauna in North

America.

The economic analysis and data used during the exclusion process

addressed impacts to: river basin or sub-basin by State, each State as

a whole, the region, and the Nation. Direct and indirect impacts on

employment, wages, and State and Federal revenues from business and

personal income taxes also were considered during the exclusion

process.

Threshold of Significant Economic Impact

To establish the threshold for significant economic impact, impacts

were evaluated in the context of the normal fluctuations of the economy

(Brookshire et al. 1994). Over the period 1959-1991, the growth rate of

the national economy (measured as percentage change in Gross Domestic

Product) varied from -2.2 percent to 6.2 percent. The mean growth rate

was 2.85 percent (with a standard deviation (SD) of 2.26 percent). Over

the same period, the average unemployment rate was 5.95 percent

(SD=1.52 percent). Impacts that lie within this range are within the

normal fluctuations of the economy and are able to be absorbed by the

economy. A conservative threshold for significant impacts would be a 1

percent SD from the projected baseline. If changes in employment or

output due to critical habitat at a State level exceed this threshold,

then that area of critical habitat should be considered for economic

exclusion.

Various flow and nonflow impacts were evaluated in the economic

analysis (Brookshire et al. 1993, 1994). Impacts associated with

providing flows for fishes, including reoperation of mainstream dams,

constituted the greatest monetary impacts. Flows in one reach may be

dependent on the flows from reaches upstream. Therefore, even though a

reach may be excluded for economic reasons, those economic impacts may

not disappear due to downstream flow requirements of the fish. Thus,

the smallest unit examined for economic impact was an individual river

except for the mainstem Colorado River, which was by river reach.

Many of the critical habitat reaches were designated for more than

one of the endangered fishes. Therefore, some reaches were needed for

the eventual recovery of one species, and also needed to prevent

extinction of another. The dual nature of many of the designated

reaches and other issues made the exclusion process complex.

Conservation and Extinction as Factors in Designating Critical Habitat

The Act defines ``conservation'' to include the use of all means

necessary to bring about the recovery of an endangered or threatened

species. Section 7(a)(2) prohibitions against the destruction or

adverse modification of critical habitat apply to actions that would

impair survival and recovery of a listed species. As a result of the

link between critical habitat and recovery, these prohibitions should

protect the value of critical habitat until recovery. Survival and

recovery, mentioned in the definitions of adverse modification and

jeopardy, are conceptually related. The survival of a species may be

viewed, in part, as a progression between extinction and recovery of

the species. The closer a species is to recovery, the greater the

certainty of its continued survival. The terms ``survival'' and

``recovery'' differ by the degree of confidence about the ability of a

species to persist in nature over a given period.

Critical habitat consists of areas that contain elements that are

essential to the conservation of a listed species. Critical habitat

identifies areas that should be considered in the conservation effort

and provides additional protection to those areas through section 7

consultation. Critical habitat is designated to contribute to a

species' conservation; however, not all areas proposed as critical

habitat may be necessary to prevent extinction. Consequently, some

areas or portions of areas may be excluded due to economic

considerations, provided that such exclusions would not result in the

extinction of the species.

In its designation of critical habitat for the four Colorado River

fishes, the Service has identified habitat required for recovery of

each species and delineated reaches that contain habitat features

needed for spawning, rearing, feeding, and migration. Species

conservation is related to a number of factors, such as the number of

individuals, the amount of habitat, the condition of the species and

its habitat, the species' reproductive biology, and the genetic

composition of the remaining populations. Through its previous efforts

(e.g., section 7 consultation, research), the Service also has

identified biologically important areas that still support these

endangered fish. Additionally, important reaches have been identified

in recovery plans for the Colorado squawfish, humpback chub, and

bonytail chub. The Recovery Implementation Programs in the Upper

Colorado River and San Juan River Basins have also identified essential

reaches for these species. Although all areas proposed are important to

conservation, those areas currently supporting the largest remaining

populations may be key to the long-term survival of these species.

Additionally, the physical and ecological relationships between these

areas are an important consideration.

Extinction of the four Colorado River fishes would most likely

occur as a result of the presence and continued introductions of

nonnative fishes, significant changes in the hydrologic cycle,

increased fragmentation and channelization of their habitat, and

decreased water quality. Although a single action could result in

extinction, the cumulative reduction in suitable habitat resulting from

many actions also could lead to species extinction. Because these

species are long-lived, the specific effects of some impacts are

difficult to establish. Therefore, the exclusion analysis focuses not

only on specific rivers and/or reaches, but also on their relationship

to other reaches in evaluating whether or not extinction would be

probable if a reach were excluded. Such factors as: (1) Current

population status, (2) habitat quality (e.g., presence of spawning

sites, nursery areas, and condition of the habitat), (3) geographical

distribution of the populations, (4) genetic variability within the

population, and (5) the relationship between critical habitat units

were considered.

In order to determine river reaches required to prevent extinction

(ensure survival) of these fishes, the Service relied upon available

biological information and approved recovery plans. Information

relating to the species' biological and ecological needs, such as

habitat, reproduction, rearing, and genetics, was used in determining

if an area was needed to prevent extinction of the species. Where

enough information was available, specific recovery plans presented

downlisting and delisting criteria. Downlisting criteria were generally

equated to the survival level; delisting criteria were related to the

recovery level. Because no recovery plan has been prepared for the

razorback sucker, reaches required for its survival (downlisting) and

recovery (delisting) may change as a recovery plan is developed by the

Service and the Colorado River Fishes Recovery Team.

Exclusion

After considering the economic and other factors that may be

pertinent to any decision to exclude areas from designation as critical

habitat, including information provided during the public comment

period, the Service determined that no exclusions were justified due to

economic and other relevant impacts.

Critical Habitat Designation

Critical habitat for each species is shown by State in Figure 1 and

summarized in Table 4. The 100-year flood plain delineates the lateral

boundary of the critical habitat for the razorback sucker and Colorado

squawfish. This boundary encompasses the productive areas adjacent to

the rivers, including the confluence of smaller tributaries and other

habitats that provide essential fish habitat when inundated.

Figure 1. Map of combined critical habitat for the four Colorado River

endangered fishes.

BILLING CODE 4310-55-P

TR21MR94.000

BILLING CODE 4310-55-C

Table 4.--River Kilometers (Miles) of Critical Habitat for Four Endangered Colorado River Fishes

----------------------------------------------------------------------------------------------------------------

Razorback Colorado Humpback Bonytail

State sucker squawfish chub chub Total\1\

----------------------------------------------------------------------------------------------------------------

Colorado....................................... 349 583 95 95 583

(217) (362) (59) (59) (362)

Utah........................................... 1107 1168 224 224 1172

(688) (726) (139) (139) (728)

New Mexico..................................... 63 97 ........... ........... 97

(39) (60) ........... ........... (60)

Arizona........................................ 832 ........... 291 ........... 832

(517) ........... (181) ........... (517)

AZ/Nevada...................................... 209 ........... ........... 103 209

(130) ........... ........... (64) (130)

AZ/California.................................. 214 ........... ........... 80 294

(133) ........... ........... (50) (183)

----------------------------------------------------------------

Basin Total\2\........................... 2776 1848 610 502 3188

(1724) (1148) (379) (312) \3\(1980)

----------------------------------------------------------------------------------------------------------------

\1\Total--Distances include all overlapping critical habitat reaches by State for all four Colorado River

endangered fish.

\2\Basin Total--Distances include total extent of critical habitat by species for the entire Basin.

\3\Total Basin Total--Note that the sum of critical habitat by species is greater than actual river distance due

to extensive overlap.

Razorback Sucker

The Service is designating 15 reaches of the Colorado River system

as critical habitat for the razorback sucker. These reaches total 2,776

km (1,724 mi) as measured along the center line of the river within the

subject reaches (Table 4). This represents approximately 49 percent of

the historical habitat for the species. In the Upper Basin, critical

habitat is designated for portions of the Green, Yampa, Duchesne,

Colorado, White, Gunnison, and San Juan Rivers. Portions of the

Colorado, Gila, Salt, and Verde Rivers are designated in the Lower

Basin. These reaches flow through a variety of landownerships, both

public and private. The amount of critical habitat for the razorback

sucker by landownership in kilometers of shoreline is presented in

Table 5.

Table 5.--Ownership of Shoreline in Kilometers (Miles) for Critical

Habitat for the Endangered Colorado River Fishes\1\

------------------------------------------------------------------------

Razorback Colorado Humpback Bonytail

Ownership\2\ sucker squawfish chub chub

------------------------------------------------------------------------

NPS................. 1,955 900 545 676

(1,215) (559) (338) (420)

BLM................. 1,140 1,119 203 114

(708) (695) (126) (71)

USFS................ 380 0 0 0

(236) ........... ........... ...........

USFWS............... 159 35 0 40

(99) (22) ........... (25)

Tribal.............. 894 451 444 97

(555) (280) (276) (60)

State Lands......... 63 79 1 40

(39) (49) (TR21MR94.001

BILLING CODE 4310-55-P

* * * * *

Humpback Chub (Gila cypha)

Description of areas taken from BLM 1:100,000 scale maps (available

from BLM State Offices): Rangely, CO 1989; Canyon of Lodore, CO 1990;

Seep Ridge, UT/CO 1982; Vernal, UT/CO 1982; Grand Junction, CO 1990;

Moab, UT/CO 1985; La Sal, UT/CO 1985; Tuba City, AZ 1983; Peach

Springs, AZ 1980; Grand Canyon, AZ 1980; Mt. Trumbull, AZ 1979.

Colorado: Moffat County. The Yampa River from the boundary of

Dinosaur National Monument in T.6N., R.99W., sec. 27 (6th Principal

Meridian) to the confluence with the Green River in T.7N., R.103W.,

sec. 28 (6th Principal Meridian).

Utah: Uintah County; and Colorado: Moffat County. The Green River

from the confluence with the Yampa River in T.7N., R.103W., sec. 28

(6th Principal Meridian) to the southern boundary of Dinosaur National

Monument in T.6N., R.24E., sec. 30 (Salt Lake Meridian).

Utah: Uintah and Grand Counties. The Green River (Desolation and

Gray Canyons) from Sumner's Amphitheater in T.12S., R.18E., sec. 5

(Salt Lake Meridian) to Swasey's Rapid in T.20S., R.16E., sec. 3 (Salt

Lake Meridian).

Utah: Grand County; and Colorado: Mesa County. The Colorado River

from Black Rocks in T.10S., R.104W., sec. 25 (6th Principal Meridian)

to Fish Ford River in T.21S., R.24E., sec. 35 (Salt Lake Meridian).

Utah: Garfield and San Juan Counties. The Colorado River from Brown

Betty Rapid River in T.30S., R.18E., sec. 34 (Salt Lake Meridian) to

Imperial Canyon in T.31S., R.17E., sec. 28 (Salt Lake Meridian).

Arizona: Coconino County. The Little Colorado River from river mile

8 in T.32N., R.6E., sec. 12 (Salt and Gila River Meridian) to the

confluence with the Colorado River in T.32N., R.5E., sec. 1 (Salt and

Gila River Meridian).

Arizona: Coconino County. The Colorado River from Nautiloid Canyon

in T.36N., R.5E., sec. 35 (Salt and Gila River Meridian) to Granite

Park in T.30N., R.10W., sec. 25 (Salt and Gila River Meridian).

Known constituent elements include water, physical habitat, and

biological environment as required for each particular life stage for

each species.

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Colorado Squawfish (Ptychocheilus lucius)

Description of areas taken from BLM 1:100,000 maps (available from

BLM State Offices): Canyon of Lodore, CO 1990; La Sal, UT/CO 1985;

Rangely, CO 1989; Delta, CO 1989; Grand Junction, CO 1990; Hite

Crossing, UT 1982; Vernal, UT/CO 1990; Craig, CO 1990; Bluff, UT/CO

1985; Moab, UT/CO 1985; Hanksville, UT 1982; San Rafael Desert, UT

1985; Huntington, UT 1982; Price, UT 1989; Farmington, NM 1991; Navajo

Mountain, UT/AZ 1982. The 100-year flood plain 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 flood plain.

Only areas of flood plain containing constituent elements are

considered critical habitat.

Colorado: Moffat County. The Yampa River and its 100-year flood

plain from the State Highway 394 bridge in T.6N., R.91W., sec. 1 (6th

Principal Meridian) to the confluence with the Green River in T.7N.,

R.103W., sec. 28 (6th Principal Meridian).

Utah: Uintah, Carbon, Grand, Emery, Wayne, and San Juan Counties;

and Colorado: Moffat County. The Green River and its 100-year flood

plain from the confluence with the Yampa River in T.7N., R.103W., sec.

28 (6th Principal Meridian) to the confluence with the Colorado River

in T.30S., R.19E., sec. 7 (Salt Lake Meridian).

Colorado: Rio Blanco County; and Utah: Uintah County. The White

River and its 100-year flood plain from Rio Blanco Lake Dam in T.1N.,

R.96W., sec. 6 (6th Principal Meridian) to the confluence with the

Green River in T.9S., R.20E., sec. 4 (Salt Lake Meridian).

Colorado: Delta and Mesa Counties. The Gunnison River and its 100-

year flood plain from the confluence with the Uncompahgre River in

T.15S., R.96W., sec. 11 (6th Principal Meridian) to the confluence with

the Colorado River in T.1S., R.1W., sec. 22 (Ute Meridian).

Colorado: Mesa and Garfield Counties; and Utah: Grand, San Juan,

Wayne, and Garfield Counties. The Colorado River and its 100-year flood

plain from the Colorado River Bridge at exit 90 north off Interstate 70

in T.6S., R.93W., sec. 16 (6th Principal Meridian) to North Wash

including the Dirty Devil arm of Lake Powell up to the full pool

elevation in T.33S., R.14E., sec. 29 (Salt Lake Meridian).

New Mexico: San Juan County; and Utah: San Juan County. The San

Juan River and its 100-year flood plain from the State Route 371 Bridge

in T.29N., R.13W., sec. 17 (New Mexico Meridian) to Neskahai Canyon in

the San Juan arm of Lake Powell in T.41S., R.11E., sec. 26 (Salt Lake

Meridian) up to the full pool elevation.

Known constituent elements include water, physical habitat, and

biological environment as required for each particular life stage for

each species.

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Razorback Sucker (Xyrauchen texanus)

Description of areas taken from BLM 1:100,000 scale maps (available

from BLM State Offices): Rangely, CO 1989; Canyon of Lodore, CO 1990;

Seep Ridge, UT/CO 1982; La Sal, UT/CO 1985; Westwater, UT/CO 1981; Hite

Crossing, UT 1982; Glenwood Springs, CO 1988; Grand Junction, CO 1990;

Delta, CO 1989; Navajo Mountain, UT/AZ 1982; Vernal, UT/CO 1990; Craig,

CO 1990; Bluff, UT/CO 1985; Moab, UT/CO 1985; Hanksville, UT 1982; San

Rafael Desert, UT 1985; Huntington, UT 1982; Price, UT 1989; Tuba City,

AZ 1983; Lake Mead, NV/AZ 1981; Davis Dam, AZ/NV/CA 1982; Parker, AZ/CA

1980; Yuma, AZ/CA 1988; Safford, AZ 1991; Globe, AZ 1980; Clifton, AZ/

NM 1975; Prescott, AZ 1982; Theodore Roosevelt Lake, AZ 1982; Grand

Canyon, AZ 1980; Mt. Trumbull, AZ 1979; Boulder City, NV/AZ 1978;

Blythe, CA/AZ 1976; Trigo Mountains, AZ/CA 1988; Sedona, AZ 1982;

Payson, AZ 1988; and U.S. Forest Service map: Tonto National Forest,

Phoenix, AZ. The 100-year flood plain for many areas is detailed in

Flood Insurance Rate Maps (FIRM) published by and available through the

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 flood plain. Only areas of flood plain containing constituent

elements are considered critical habitat.

Colorado: Moffat County. The Yampa River and its 100-year flood

plain from the mouth of Cross Mountain Canyon in T.6N., R.98W., sec. 23

(6th Principal Meridian) to the confluence with the Green River in

T.7N., R.103W., sec. 28 (6th Principal Meridian).

Utah: Uintah County; and Colorado: Moffat County. The Green River

and its 100-year flood plain from the confluence with the Yampa River

in T.7N., R.103W., sec. 28 (6th Principal Meridian) to Sand Wash in

T.11S., R.18E., sec. 20 (6th Principal Meridian).

Utah: Uintah, Carbon, Grand, Emery, Wayne, and San Juan Counties.

The Green River and its 100-year flood plain from Sand Wash at T.11S.,

R.18E., sec. 20 (6th Principal Meridian) to the confluence with the

Colorado River in T.30S., R.19E., sec. 7 (6th Principal Meridian).

Utah: Uintah County. The White River and its 100-year flood plain

from the boundary of the Uintah and Ouray Indian Reservation at river

mile 18 in T.9S., R.22E., sec. 21 (Salt Lake Meridian) to the

confluence with the Green River in T.9S., R.20E., sec. 4 (Salt Lake

Meridian).

Utah: Uintah County. The Duchesne River and its 100-year flood

plain from river mile 2.5 in T.4S., R.3E., sec. 30 (Salt Lake Meridian)

to the confluence with the Green River in T.5S., R.3E., sec. 5 (Uintah

Meridian).

Colorado: Delta and Mesa Counties. The Gunnison River and its 100-

year flood plain from the confluence with the Uncompahgre River in

T.15S., R.96W., sec. 11 (6th Principal Meridian) to Redlands Diversion

Dam in T.1S., R.1W., sec. 27 (Ute Meridian).

Colorado: Mesa and Garfield Counties. The Colorado River and its

100-year flood plain from Colorado River Bridge at exit 90 north off

Interstate 70 in T.6S., R.93W., sec. 16 (6th Principal Meridian) to

Westwater Canyon in T.20S., R.25E., sec. 12 (Salt Lake Meridian)

including the Gunnison River and its 100-year flood plain from the

Redlands Diversion Dam in T.1S., R.1W., sec. 27 (Ute Meridian) to the

confluence with the Colorado River in T.1S., R.1W., sec. 22 (Ute

Meridian).

Utah: Grand, San Juan, Wayne, and Garfield Counties. The Colorado

River and its 100-year flood plain from Westwater Canyon in T.20S.,

R.25E., sec. 12 (Salt Lake Meridian) to full pool elevation, upstream

of North Wash and including the Dirty Devil arm of Lake Powell in

T.33S., R.14E., sec. 29 (Salt Lake Meridian).

New Mexico: San Juan County; and Utah: San Juan County. The San

Juan River and its 100-year flood plain from the Hogback Diversion in

T.29N., R.16W., sec. 9 (New Mexico Meridian) to the full pool elevation

at the mouth of Neskahai Canyon on the San Juan arm of Lake Powell in

T.41S., R.11E., sec. 26 (Salt Lake Meridian).

Arizona: Coconino and Mohave Counties; and Nevada: Clark County.

The Colorado River and its 100-year flood plain from the confluence

with the Paria River in T.40N., R.7E., sec. 24 (Gila and Salt River

Meridian) to Hoover Dam in T.30N., R.23W., sec. 3 (Gila and Salt River

Meridian) including Lake Mead to the full pool elevation.

Arizona: Mohave County; and Nevada: Clark County. The Colorado

River and its 100-year flood plain from Hoover Dam in T.30N., R.23W.,

sec. 1 (Gila and Salt River Meridian) to Davis Dam in T.21N., R.21W.,

sec. 18 (Gila and Salt River Meridian) including Lake Mohave to the

full pool elevation.

Arizona: La Paz and Yuma Counties; and California: San Bernardino,

Riverside, and Imperial Counties. The Colorado River and its 100-year

flood plain from Parker Dam in T.11N., R.18W., sec. 16 (Gila and Salt

River Meridian) to Imperial Dam in T.6S., R.22W., sec. 25 (Gila and

Salt River Meridian) including Imperial Reservoir to the full pool

elevation or 100-year flood plain, whichever is greater.

Arizona: Graham, Greenlee, Gila, and Pinal Counties. The Gila River

and its 100-year flood plain from the Arizona-New Mexico border in

T.8S., R.32E., sec. 34 (Gila and Salt River Meridian) to Coolidge Dam

in T.3S., R.18E., sec. 17 (Gila and Salt River Meridian), including San

Carlos Reservoir to the full pool elevation.

Arizona: Gila County. The Salt River and its 100-year flood plain

from the old U.S. Highway 60/State Route 77 bridge (unsurveyed) to

Roosevelt Diversion Dam in T.3N., R.14E., sec. 4 (Gila and Salt River

Meridian).

Arizona: Yavapai County. The Verde River and its 100-year flood

plain from the U.S. Forest Service boundary (Prescott National Forest)

in T.18N., R.2E., sec. 31 to Horseshoe Dam in T.7N., R.6E., sec. 2

(Gila and Salt River Meridian), including Horseshoe Lake to the full

pool elevation.

Known constituent elements include water, physical habitat, and

biological environment as required for each particular life stage for

each species.

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Dated: March 10, 1994.

George T. Frampton,

Assistant Secretary for Fish and Wildlife and Parks, Department of the

Interior.

[FR Doc. 94-6508 Filed 3-16-94; 11:26 am]

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