7152

• UCREFRP Catalog Number: 7152
• Author: Holden, P. B.
• Title: Relationship between Flows in the Yampa River and Success of Rare Fish Populations in the Green River System.
• USFW Year: 1980.
• USFW - Doc Type: Logan, Utah.
• Copyright Material: NO

INTRODUCTION

The National Park Service is in the process of quantifying their
reserve right claim for water levels in the Yampa River of Colorado

within the boundaries of Dinosaur National Monument. The Monument's

need for water is based on a number of factors which are inherent in

the reason for its formation, i.e., the natural features that it pro-

tects and manages for the people of the nation. One of these factors
is the habitat of several fish species endemic to the Colorado River
system. Two of these species, the Colorado squawfish (Ptychocheilus
lucius) and humpback chub (Gila cypha), are listed as endangered;
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while two others, the bony tail chub (Gila elegans) and the razorback
sucker (Xyrauchen texanus), are proposed for listing.
Data collected over the last 10-20 years in the Colorado River
system have indicated that loss of flow may be one of the major factors
affecting the endemic fishes, especially Colorado squawfish (Joseph
et ale 1977; Holden 1977; Holden 1979). Two major influences of flow

on these endemic species are hypothesized.

1. Reduced flows due to regulation of the rivers in the

Colorado system have tended to alter the instream
habitat to the detriment of the rare fishes.

2. Successful reproduction of Colorado squawfish, and

perhaps the other species, is dependent on natural

or near natural flows.