9578

• UCREFRP Catalog Number: 9578
• Author: Hamilton, S. J. and e. al.
• Title: The Evaluation of Contaminant Impacts on Razorback Sucker Held in Flooded Bottomland Sites Near Grand Junction, Colorado - 1997.
• USFW Year: 2001.
• USFW - Doc Type: CAP6-WW,
• Copyright Material: NO

INTRODUCTION

Endangered fish

As a result of its long isolation, the Colorado River basin supports some of the most
distinctive ichthyofauna in North America (Figure 1). Several fish species have declined in the
basin, which originally contained 32 native species, of which 75% were endemic (Minckley
1991). The upper Colorado River provides critical habitats for four endangered fish species,
Colorado pikeminnow (Ptychocheilus lucius), razorback sucker (Xyrauchen texanus), humpback
chub (Gila cypha), and bonytail (Gila elegans) (USFWS 1994). A combined approach for
recovery of the four endangered fish in the upper Colorado River basin has been undertaken by
the Upper Colorado River Endangered Fish Recovery Program, which was initiated in 1987
(USFWS 1987). The upper basin is defined as the portion of the basin above Glen Canyon Dam.
The goal of this IS-year program is to reestablish self-sustaining populations of the four species
while allowing continued development of water.
The reasons for the decline of these species are related to a combination of factors
including stream alteration (dams, irrigation withdrawals, dewatering, channelization), loss of
habitat (spawning sites and backwater nursery areas), changes in flow regime, blockage of
migration routes, water temperature changes, competition with and predation by introduced
species, parasitism, and changes in food base (USFWS 1987). Irrigation and pollution
were suggested in 1976 as possible contributing factors to the decline of endangered fish
(Seethaler et al. 1979). The U.S. Fish and Wildlife Service's (USFWS) Colorado River Fishery
Project (CRFP), a component of the Recovery Program, contracted in 1981 to have short-term .
tests conducted to determine the toxicity of several inorganic and organic chemicals to Colorado
pikeminnow and humpback chub (Beleau and Bartosz 1982). Those tests were conducted with
older life stages of these fish, which tend to be less sensitive than young life stages (Rand and
Petrocelli 1985), and seemed to indicate that contaminants were not adversely effecting the
endangered fish.

Contaminant studies in the Colorado River basin

Following the discovery of selenium-contaminated irrigation return waters in the San
Joaquin Valley of central California in 1982, the Department of the Interior (DOl) initiated the
National Irrigation Water Quality Program (NIWQP) to identify other areas in the western U.S.
that have water quality problems induced by irrigation drainage (Feltz et al. 1991). The NIWQP
investigations focused on irrigation drainage facilities constructed by the DOl, where the
drain water was to a national wildlife refuge, or had the potential to impact migratory birds or
endangered species. The upper Colorado River basin including the middle Green River basin of
Utah and the upper Colorado, Gunnison, and Uncompahgre rivers in northwestern Colorado
were identified as areas needing further study. Analysis of water, bottom sediment, and biota
collected since 1986 from the middle Green River basin and the Grand Valley, located in western
Colorado and includes a portion of the Colorado, Gunnison, and Uncompahgre rivers, have
confirmed the presence of inorganic elements including seleni um at concentrations that could be
potentially harmful to fish and wildlife (Butler et al. 1989, 1991, 1994, 1996; Stephens et al.
1988, 1992; Peltz and Waddell 1991).
The NIWQP studies provided a basic foundation of survey information on the occurrence

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