7906

• UCREFRP Catalog Number: 7906
• Author: Upper Colorado River Basin Instream Flow Team.
• Title: Green River, Determination of Flow Needs Using the Physical Habitat Simulation System ‎(PHABSIM)‎ in the Green River, Utah - Draft.
• USFW Year: 1988.
• USFW - Doc Type: \
• Copyright Material: NO

Table 16. The optimum weighted-useable-area (WUA) for Colorado squawfish
and razorback suckers with the 1987 suitability index curves
and the modified curves at 0.6 and 0.8 tenths depths in the
Green River at the Ruple Ranch study site, river mile 332.3,
with 90 percent flow windows.
1987 Suitability Index Curves Modified Suitability Index Curves
0.6 0.8 0.6 0.8
Colorado squawfish
Adult
1200 ( 700-2200> 1500 ( 700-3000) 1000 ( 500-2000) 1500 ( 500-2700)
Deposition
1500 (1100-2400) 1500 (1100-2500) 3000 (1800-4200) 4200 (2200-5600)
Razorback sucker
May & June
2200 ( 900-4200) 3000 (1000-5600) 3000 (1100-5600) 5600 (1600-7700)
July-October
1600 (1100-2300) 1900 (1400-2700) 1600 (1100-2300) 1900 (1400-2700)
III. DISCUSSION
An over all flow window for the Green River at the Ruple Ranch site
can be developed from any of the values given in Table 16. At this point,
however any recon~nendation will need to be verified. before it can be used
in a decision making process. If it is assumed that 0.8 depth is a more
accurate measurement of velocity use than 0.6 depth, and that the modified
curves are more realistic diagrams of habitat use than the original
curves, then an over-all periodic chart for optimum flows can be developed
(Table 17).
From the results a flow regime can be recommended that will optimize
habitat for all species and life stages (Figure 17). This regime would
suggest a flow of 1700 cfs October to April, 2700 cfs in May, and 2200 cfs
mid-June to September. In comparing these results to the historic data,
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