9520

• UCREFRP Catalog Number: 9520
• Author: Haines, G. B., D. Irving and T. Modde.
• Title: White River Base Flow Study for Endangered Fishes, Colorado and Utah, 1995-1996.
• USFW Year: 2004.
• USFW - Doc Type: 5D,
• Copyright Material: NO

EXECUTIVE SUMMARY

Compared to many western rivers, water depletions from the White River have been

minor, consisting of only 5% of the annual basin yield. Although the hydrology of the White

River is relatively unaltered, a mainstem barrier, Taylor Draw Dam, precludes upstream fish

passage. The dam operates under the guidelines of a Federal Energy Regulatory Commission

permit requiring "run of the river" management. Thus, the water yield and hydrograph of the
White River have not been greatly altered.

The purpose of this study was to identity the base flow needs of endangered fish, i.e.,

adult Colorado pikeminnow (Pytchocheilus lucius), in the White River. Our approach was to

evaluate changes in available habitat as flows receded after runoff This approach defined flows

which protect Colorado pikeminnow habitat and biological productivity associated with riftle

habitat. Determination of both habitat availability and productivity were made using physical

habitat simulations among various flows. Curve break analysis was used to identify the flow

where the greatest rate of habitat change occurred.

Study results suggested that multiple flow levels are required to meet the needs of the

White River Colorado pikeminnow. To cue the fish to migrate, a natural hydrograph is needed

during spring runoff. To provide for passage over riflles, flows >300 cfs are apparently needed.

To maintain riflle productivity during base flow period (i.e., cover 95% of the surface area), flows

of 400-500 cfs are needed; and ifflows fall below 161 cfs, rime habitat declines rapidly.

This study had several shortcomings as a basis for determining future flow needs of

Colorado pikeminnow in the White River. As described in Model Critique, the precision of

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