WSP07668

• File Number: 8240.200.10.C.5
• Description: UCRBRIP
• Basin: Colorado Mainstem
• Date: 3/21/1994
• Author: USFWS
• Title: Federal Register - Determination of Critical Habitat for Four Colorado River Endangered Fishes - Final Rule
• Water Supply Pro - Doc Type: Publication

Federal Register / Vol. 59, No, 54 / Monday, March 21, 1994 / Rules and Regulations

humpback chub in the Grand Canyon,
the Lower Colorado River for Colorado
sqw.wfish, and the Duchesne River up
to the confluence with the Uintah River
for razorback sucker and Colorado
squawfish.
Issue 33: Many respondents
questioned the need to designate flood
plain areas. Reasons provided include:
the river is too regulated to allow floods;
agricultural. mining, oil and gas,
residential, tr8nspartation facilities, and
municipal development has occurred;
and there will be considerable economic
impact, They stated that inclusion of
flood plain is not biologically
supportable. Others recommended
alternate flood plain elevations.
Service Response: Large river systems
are composed of the mainstream
channels and adjacent habitats that are
inundated during the higher water
levels that are usually associated With
spring flows, These seasonally flooded
habitats are major contributors to the
natural productivity Of the river system
by providing nutrient inputs and .
makiJlg terrestrial food sources available
to aquatic organisms. The extent of .
flooded wetlands in the Colorado River
has been reduced by the construction .
and openltion of water resO!lfCe .'
develbpment projects. The nom.;n;ng .
flood plain areas have great importance
for recovery of endangered fish.
Recent studies in tlie Colorado River
systeni have shown that the life . .
histories aDd welfare of native riverine
fishes iu-e linked with. the maintenance
of a naturaioihistorical flow regimen
(i,e.. a hydrological pattern of high
spring and low autumn-winter flows
that v8IYin magnitude and duration,
depanding on annual precipitation
patterns and runoff from snowmelt).
Ichthyologists have predJcted that .
stream regUlation that results in loss of
flooding will result in extirpation of
native fish species in the Colorado River
system.
Inundsted flood plains (bottom land
habitats) are important for razorback
sucker, Colorado squawfish, and
perhaps the bonytail and humpback
chubs. Wooded bottom lands, side and
second8IY channels, oxbow lakes, and
flood plain wetlands provide nutrients,
food,.cover, and other features necessary
for various life stages of these'iish, In
order to delineate such areas in
designating critical habitat, the Service
used the 10o-year flood elevation (100.
year flood plainl.1n no way is this
determination meant to include all land
within the 10o-year flood plain as
critical habitat nor'does it imply a
specific frequency of flooding will be
required as part of the rule. Only those
areas that provide one or more of the

constituent elements can be considered
for inclusion as critical habitat. Areas
within the 1 OO.year flood plain that
have been previously developed are not
likely ta provide constituent elements
when flooded,' . .
Issue 34: Several respondents
. believed that the four fish species do not
have enough in common biologically
(habitat use, life history, etc.) to be
included in this single designation. It
will be too difficult to manage all four
fish together,
Service Response: The historical
ranges of the four species overlap. While
the specific habitat components
required by each species may not be
identical, historical conditions created a
variety of acceptable habitats within a
reach of the river. This variety of
habitats enabled more than one of the
four species to use the area. Because the
fish naturally.coexisted together over
much of their ranges,management
efforts to restore habitats will likely
provide the diversity of habitat
components needed to support these
species without having to provide
-discrete and separate management
programs, 0'.
Issue 35: Many respondents stated
that the area proposed for designation
was too l8r2e.' .
Service 1fesponse: The size of the
critical habitat areas i8 required to
ensure that the life history requirements
for species can be met. J.arval drift.
migratory behavior. and the need to
maintain genelicdiveflllty within
species necessiUiteslarge reaches of
river be designated. The Draft Biological
Support Document provided life history
information that discusses in detail
those aspects that influence the amount
of habitat required for survival and
recovery. The designation meets the
intent of the Act in not designating the
entire historic ranges of these species.
Issue 36: Several respondents
maintainedttwtm~gmnemofthe~
areas should be the responsibility of the
land owning agency. tribal governments,
or private property owners, and that
other laws provide for the managmnent
. of wildlife and .fish, making designation
of critical habitat unnecessary,
Service Response: Federal agencies
are responsible. under the Act to insure .
that their actions do not jeopardize the
continued existence of or adversely
modify or destroy the critical habitat of
a listed species, They are required to .
consider the presence of these species in
their management, No other Federal or
State law provides this level of
protection for these resources. Non-
Federal entities (States. tribes. or
individuals) are not bound to consider
critical habitat unless they are receiving

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Federal funding or pennits to undertake
a management action on their lands. In
that case, the Federal agency's
responsibility is invoked.
Issue 37: Some letters indicated that
the selection of boundaries appeared
related to landmarks rather than strictiy
for biological reasons,
Service Response: Exact reach
endpoints and/or boundaries were
indeed chosen for landmarks
recognizable to an on.the.ground
observer. The Service believes that it is
important that the boundaries of critical
habitat be as evident as possible. While
each reach mey have been adjusted in
a minor way to landmarks at the upper
and lower tennini, the biological basis
for reach selection was not
compromised.
Issue 38: A few respondents indicated
that the designation of critical habitat
will improve water quality
Service Response: Maintaining the
flows, habitat. and chemical parameters
required by these fish species may have
an inlluence on the changes in water
quality that can be allowed within the
critical habitat area. It is not certain how
much. if any. change to existing water
quality would result. .
Issue 39: Somerespondeilts asked-
questions regarding the designation of
reservoirs and regarding full pool
elevation. . .
Service Response: nata indicates that
adult razorback suckers and bonytail .
chubs can survive in reservoirs. Large
populations .of these fish.can be .
maintained in reservoirs. allowing for
maintenance of genetic variability and
providing stock for reintroduction and
research, The full pool level in a
reservoir is defined as the water surface
elevation at full capacity, This does not
mean that reservoirs should be
maintained at full pool elevations, but
that habitat is protected regardless of
reservoir pool elevation.
Issue 40: Some respondents believed
that the flow requirements for fish used
in the economic analysis had an
inadequate biological base.
Service Response: The best available
commercial and scientific data were
used in developing the flow scenarios
used in the economic analysis. Flows.
for several river reaches have been
developed by the Service as part of
project reviews or RIP activities, These
flow recommendations have been
published by the Service in reports or
biological opinions. For those river
reaches with no published flow
recommendation, the Service developed
flow scenarios using the best available
hydrological and biological information.
Issue 41: Several respondents
believed the Service did not address the