9603

• UCREFRP Catalog Number: 9603
• Author: Clayton, R. and A. Gilmore.
• Title: Flaming Gorge Environmental Impact Statement Hydrologic Modeling Study Report - Results of Action and No Action Alternative Analysis.
• USFW Year: 2001.
• USFW - Doc Type: \
• Copyright Material: NO

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7
TABLE 1 C t II" C't' A I . fA.

dNA. MdlR It

on ro mg n ena nalysls 0 chon an 0 ctlOn o e esu s
Spring Peak Flow Recommendations Target Model Results
for Reach 2 0/0
Action Action No
(ALL-l ) (ALL) Action
Achieve Peak at Jensen >= 26,400 cfs 10% 11.4% 16.4% 5.0%
Sustained Peak at Jensen >= 22,700 cfs 10% 10.8% 12.3% 4.1%
for at least 2 weeks.
Sustained Peak at Jensen >= 18,600 cfs 10% 9.5% 18.1% 5.0%
for at least 4 weeks.
Achieve Peak at Jensen >= 20,300 cfs 30% 44.7% 57.7% 40.4%
Sustain Peak at Jensen >= 18,600 cfs 40% 18.2% 43.10/0 14.0%
for at least 2 weeks.
Achieve Peak at Jensen >= 18,600 cfs 50% 60.2% 66.0% 58.9%
Achieve Peak at Jensen >= 8,300 cfs 100% 99.7% 99.7% 98.5%
Sustain Peak at Jensen >= 8,300 cfs 90% 96.9% 96.9% 96.9%
At least I week.
Sustain Peak at Jensen >= 8,300 cfs 98% 97.3% 97.3% 97.3%
at least 2 days except in extreme dry
years.

Reservoir Water Surface Elevation Results

For each month of the model run, from January 2002 to December 2040, there are 65
elevations that could potentially occur in any given month (one elevation for each trace). These
monthly data sets have been sorted from lowest to highest. The 10th, 50th, and 90th percentile
values have been selected from each set. Figure 1 shows the 90th percentile elevations that
occurred for all three runs of the model for the first 10 years of the model run. The results in
Figure 1 do not represent anyone particular elevation trace. Rather, these curves can best be
thought of as a boundary elevation that will be exceeded 10% of the time. To illustrate how
individual traces fluctuate through time, trace 54, which achieved the 90% boundary elevation in
July, 10 years into the model run, is included in the figure. The amplitude of the curves from year
to year indicated how much water was being stored during the spring for release later in the year.
The smaller the amplitude, the less storage that took place throughout the year and the less
change in elevation that occurred from year to year. Both the Action(ALL) and the Action(ALL-
1) model runs have smaller amplitudes than the No Action Alternative indicating less active
storage and less elevation change during the year.