WSP00537

• File Number: 8220.112.K
• Description: Dallas Creek Participating Project
• State: CO
• Basin: Gunnison
• Water Division: 4
• Date: 11/16/1979
• Author: USDOI - USFWS
• Title: Biological Opinion for Dallas Creek Project-Colorado
• Water Supply Pro - Doc Type: Biological Opinion

- .

-----~

2

human alteration of the river env:l.ronment. Major impoundments and water
diversions have depleted water and altered temperature, turbidity, and
stream flow patterns, thus reducing habitat for both fishes.

Historically, the Colorado squawfish and humpback chub were found in the
Gunnison and Uncompahgre River drainages. Squawfish were reported to be
common in the Gunnison.as far upstream as Delta, Colorado. All confirmed
historical reports of squawfish collected in the Gunnison drainage were
large specimens, suggesting most were spawning migrants from the Colorado
River. Reports of large migrations of squawfish were common in the
early 1900' s. '

Except for a slight increase in' the squawfish population believed to
occur between 1940 and 1947 as a result of above normal runoff, the
squawfish population has continually declined. This dec~ine of squawfish.
and a similar decline of humpback chubs, in the lower Gunnison is attributed
to the numerous upper basin dams and irrigation diversions which have
been ,constructed over the years. Upstream migration has been retarded,
and sometimes prevented, by the structures themselves and by the reduced
spring and early summer flows caused by their operations.

h
Ii
I'
i;
I,
"
"

I',i,'
;!

,
F
Ie

~ :

"
{
,

,.:'

These low flow conditions have contributed to the reduced populations of
endemic fishes and this is reflected by the scarcity of fish in recent
collection attempts. Except for the collections by Holden and Stalnaker
in 1971, other recent collections (for example by Kidd 1976 and the
Colorado Div:l.sionof WildH.fe in 1977) have failed to turn up squawfish
and humpback chubs in areas where they once existed in the G=ison. In
addition, attempts at collection by the Fish and Wildlife Service (FWS)
in that area, in 1979 were unsuccessful.

:;.1

"
,-

.:..
~{
>.'

,

Reports show that the squawfish and humpback chub have been declining
throughout the Colorado River drainage. However, recent FWS surveys
have identified good' populations of squawfish and humpback chubs in the
Black Rocks area of Ruby Canyon and, in the Westwater Canyon along the
main Colorado River. Protection of these population strongholds and the
habitat offere~ by these canyon sections is essential for'recovery of
both species. Therefore, this biological opinion considers the cumulative
depletion of water from the Colorado River below the confluence with the
Gunnison as well as from the lower Gunnison River. Significant depletions
by projects such as Dallas Creek could affect these important downstream
populations.

~;i..

I,:

I ~.::.
!\~..

'~~
t$"1
if-'
'.
~

,,'

The pruposed Dallas Creek Project is part of th~ Colorado River Storage
Project (CRSP), which was authorized as a participating project of the
Colorado River Storage Project Act of April 11, 1956. We considered the
cumulative effects of all Gunnison River'CRSP units in developing t~s
biological opinion'and have summarized their effects below. Figure 1
shows the major projects in the G=ison River watershed that will
"affect tbe Colorado squawfish and humpback chub. The Gunnison River
contributes as much as 41 percent of the flow of the Colorado River in a
high-water year (1970) and 53 percent in a low-water year (1977) at the
border of Colorado and Utah.

,-
,

i.