7245

• UCREFRP Catalog Number: 7245
• Author: Rose, K. L. and D. R. Hann.
• Title: Consolidated Instream Flow Report, Habitat Modeling on the Green River Using the Physical Habitat Simulation System.
• USFW Year: 1989.
• USFW - Doc Type: Grand Junction, Colorado.
• Copyright Material: NO

Table 11. IFG4 measured versus predicted discharges (Q) in cubic feet per
second for each transect at Ruple Ranch study site.

Transect

Meas. 0

Pred. 0

Ratio

1 5553 5248 1.06
2 5407 5358 1.01
3 5434 5284 1.03
4 5491 5458 1.01
5 5449 5349 1.02
6 5672 5510 1.03
-,--'

3. Calculation of WeiQhted-Useable-Area

The HABTAT4 program combines the simulated hydraulic data with SI curves to
produce a WUA versus discharge relationship. The optimum stream flow for a
fish species and life stage is considered to be the discharge associated with
the highest WUA value. For the purposes of this paper, an acceptable flow
window is defined as the approximate range of flows which maintain 90 percent
of the highest WUA value at either 0.6 or 0.8 depth.

A~ the Ruple Ranch study site the year-round WUA for adult Colorado squawfish
was maximized at a flow of 1200 cfs, with a flow window between 700 and 2200
cfs at 0.6 depth. The WUA for the depositional life stage, from mid-June to
September, was maximized at 1500 cfs, with a flow window between 1100 and 2400
cfs. Similarly, the adult razorback sucker habitat was maximized at 2200 cfs,
with a flow window between 900 and 4200 cfs in May and June, and 1600 cfs,
with a flow window between 1100 and 2300 cfs from July to October (Table 12).
In general, maintaining a high percentage of physical habitat for both species
and all life stages at 0.6 depth would theoretically be accomplished with a
range of flows between 1100 and 2200 cfs.

The WUA for adult Colorado squawfish at 0.8 depth (Table 13) is maximized at
1500 cfs with a window between 700 and 3000 cfs. The depositional life stage
habitat is maximized at 1600 cfs with a window between 1100 and 2400 cfs. The
razorback sucker habitat is optimized at slightly higher flows with the
maximum habitat at 3000 cfs, with a window between 1000 and 5600 cfs in May
and June, and 1900 cfs, with a window between 1400 and 2700 cfs from July to
October. In general, a flow range between 1400 and 3000 cfs will
theoretically maintain a high percentage of physical habitat at 0.8 depth.
The WUA for adult Colorado squawfish at 0.6 and 0.8 depths with the second set
of curves modified from the review of Tyus, Jones and Trinca (1987) is 1000
cfs, with a window between 500 and 2000 cfs at 0.6 depth (Table 14), and 1500
cfs with a window between 500 and 2700 cfs at 0.8 depth (Table 15). The WUA
for the depositional life stage peaks at a flow of 3000 cfs with a window
between 1800 and 4200 cfs at 0.6 depth, and 4200 cfs, with a window between
2200 and 5600 cfs at 0.8 depth. For the months of May and June, the WUA for
razorback suckers peaks at 3000 cfs with a window between 1100 and 5600 cfs at
0.6 depth and 5600 cfs with a window between 1600 and 7700 cfs at 0.8 depth.

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