7281 ‎(2)‎

• UCREFRP Catalog Number: 7281
• Author: U.S. Fish and Wildlife Service.
• Title: Recovery Implementation Program for Endangered Fish Species in the Upper Colorado River Basin, Environmental Assessment, November 1987.
• USFW Year: 1987.
• USFW - Doc Type: Denver, Colorado.
• Copyright Material: NO

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CHAPTER IV
ENVIRONMENTAL CONSEQUENCES
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located on the Colorado River near the Colorado-Utah border,
31 miles below the confluence of the Gunnison and Colorado
Rivers) in 9 out of 10 years. Historical flows at the Stateline
gage have rarely dropped below 2,000 cfs. Between the time
Aspinall was built and 1982, this has only occurred once in the
August-September period. Between now and the year 2040 (when
the Upper Basin is expected to fully deplete its allotment under
the Compact), depletions are expected to continue to reduce
river flows. Year 2040 flows below the confluence of the
Gunnison and Colorado are projected to drop below 2,000 cfs
25 percent of the time, but only in August and September.
In the year 2040, if the interim regime was continued as the
postconsultation regime, Aspinall releases will produce between
0-500 cfs additional flow in the Gunnison River during August
and September, the exact quantity dependent on natural flow in
the Colorado River. Current Reclamation projections of future
water demand indicate that after the year 2040, 75 percent of
the time no additional releases will be needed to meet the
2,000 cfs target. Fifteen percent of the time supplemental
releases of up to 500 cfs will be supplied in August and
September. Ten percent of the time no additional releases will
be requested to meet the 2,000 cfs target (since the agreement
is for 9 out of 10 years). Future research on the Gunnison and
Colorado Rivers as a part of Section 7 consultation on the
Aspinall Unit will further evaluate the 2,000 cfs flow target
and the frequency that the target must be met.
Water right transactions involving rivers such as the Yampa and
White Rivers will attempt to preserve naturally occurring flows.
Research investigations will determine instream flow needs on
the White River and refine estimates of instream flow needs on
the Yampa River.
b. State and Private Water Management
(1) Assumptions
A year 2000 analysis was undertaken because the year 2000 is
commonly accepted as the near term planning target for most
planning endeavors and because it approximates the 15-year
timeframe for the completion of the Proposed Action. This
analysis provides insight, on a gross level, into potential "hot
spots," i.e., Upper Basin reaches where there may be conflicts
(due to depletions) between proposed development actions and
endangered fishes instream flow needs. Appendix D displays
project depletion data used to project the year 2000 flows.
(2) Impact Findings
The year 2000 analysis identified several river segments where
water development could occur. Depletions associated with these
IV-A-6

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