7046 ‎(3)‎

• UCREFRP Catalog Number: 7046
• Author: Valdez, R. A., W. J. Masslich and A. Wasowicz.
• Title: Final Report\
• USFW Year: 1992.
• Copyright Material: NO

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1.0 INTRODUCTION

This document is the Final Report submitted to Utah Division of Wildlife Resources (UDWR)
in fulfillment of Contract No. 90-2559, entitled Dolores River Native Fish Habitat Suitability Study.
This investigation was funded through the Recovery Implementation Program for Endangered Fish
Species in the Upper Colorado River Basin. The investigation included three sampling trips each in
1990 and 1991. Four trip reports were submitted, one for each of the first two sampling trips
conducted in 1990 and 1991. No trip report were submitted for Trip 3 or 6. Results from Trip 3
were summarized and integrated with the results of the first two trips into the Annual Summary
Report for 1990. Results from Trip 6 were summarized and integrated with results of previous trips
into this Final Report

1.1 Objectives

The objectives of this investigation were to:

1. Determine the extent and change in use of the Dolores River by native Colorado River fishes
with the advent of consistent flows, reduced pollutant inflow, and reduced salinity occurring
in the Dolores River Basin.

2. Assess suitability of physical, chemical, and biological attributes of the Dolores River for
endangered fish.

3, Evaluate the feasibility of reintroducing Colorado squawfish into the Dolores River to
enhance recovery of the species in the Upper Basin.

4, Issue recommendations on reintroducing Colorado squawfish into the Dolores River.

1.2 Background

The Dolores River once supported unknown numbers of Colorado squawfish (Ptychocheilus
lucius) and perhaps functioned as a spawning tributary for this species in the upper Colorado River,
Seethaler (1978) reported that T.M. Lynch seined small squawfish from Paradox Valley in 1962.
Several other collections of Colorado squawfIsh were reported during the 1950's and 1960's by
Lemons (1955), Nolting (1956), and Coon (1965). The most recent collection of Colorado squawfish
in the drainage was an unconfirmed report by Horpestad (1973), who captured seven individuals in
the San Miguel River, approximately 6 miles above it's confluence with the Dolores River. No
Colorado squawfish were captured during a fIShery survey of the Dolores River by Holden and
Stalnaker (1975) in 1971. More recent surveys by the U,S. Fish and Wildlife Service (Service) in the
early 1980's also failed to locate Colorado squawfish in the Dolores River (Valdez et at 1982).

Operations of uranium processing facilities from the late 1940's through the 1960's caused adverse
impacts to the stream biota and may have contributed greatly to the local demise of Colorado
squawfish in the Dolores River drainage, These uranium processing facilities included a uranium
concentrator at Naturita, Colorado, and a large uranium mill at Uravan, Colorado, both of which were
located on the San Miguel River within 15 miles of its confluence with the Dolores River, A
uranium concentrator plant was also located on the Dolores River near the town of Slickrock,
Colorado, approximately 60 miles above the confluence of the Dolores and San Miguel rivers.

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