7103

• UCREFRP Catalog Number: 7103
• Author: Grabowski, S. J. and S. D. Hiebert.
• Title: Green River Trophic Dynamics Study 1987
• USFW Year: 1988.
• USFW - Doc Type: Draft.
• Copyright Material: NO

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INTRODUCTION

The Green River in Wyoming, Colorado and Utah, is a major tributary
of the Colorado River and since the construction of Flaming Gorge Dam
is strongly influenced by controlled releases for power generation
from the dam. Sixty-five river miles downstream of Flaming Gorge Dam,
the Yampa River enters the Green River, and 97 miles below this confluence
the Duschesne and White Rivers enter the Green River near Ouray, Utah,
(fig. 1). These three tributaries are uncontrolled and have their
highest relative flows during the spring runoff period. Since the
construction and impoundment by Flaming Gorge Dam in the early 1960s,
there has been a subsequent reduction in the abundance of several indigenous
species of fish in the river below the dam, including the Colorado
squawfish (Ptychocheilus lucius).

The USFWS (U.S. Fish and Wildlife Service) has conducted studies of
the endangered Colorado squawfish since 1978, in both the Green River
and the upper Colorado River. These studies and others have been done
to understand the physical and biological requirements of the Colorado
squawfish. Ultimately, this information, along with results of ongoing
studies, will provide guidance to the USFWS in formulating a biological
opinion regarding operational schemes for Flaming Gorge Dam in relation
to survival and enhancement of Colorado squawfish. At present, Flaming
Gorge Dam is operated with annual moderate flows from May through October
with relatively unlimited fluctuations and flows during the remainder

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