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

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of selenium in fish collected from a variety of aquatic ecosystem components that suggested
selenium and possibly other contaminants might be sufficiently elevated to be contributing to the
decline of endangered fish. Selenium in soils of the western states is derived from weathering of
. outcrops of Cretaceous marine rocks in the Rocky Mountain and Great Plains regions, which
comprises an area of approximately 300,000 square miles (Presser et al. 1994).
The U.S. Fish and Wildlife Services' National Contaminant Biomonitoring Program
(NCBP) has documented elevated selenium concentrations in fish collected from stations located
in the upper and lower Colorado River basins. The NCBP monitors temporal and spatial trends
in concentrations of persistent environmental contaminants, including selenium, that may
threaten fish and wildlife, and was the 85th percentile as an arbitrary point distinguishing "high"
concentrations (Walsh et al. 1977, May and McKinney 1981, Lowe et al. 1985, Schmitt and
Brumbaugh 1990). Selenium concentrations in whole-body fish from the Colorado River basin
have been among the highest in the nation (Walsh et al. 1977, Lowe et al. 1985, Schmitt and
Brumbaugh 1990). In samples collected in 1972-1973, selenium concentrations exceeded the
85th percentile in fish at five of six stations in the Colorado River basin: Green River at Vernal,
UT (the only upper basin station) and Colorado River at four sites in Arizona (Imperial
Reservoir, Lake Havasu, Lake Mead, and Lake Powell). In 1978-1981 and 1984, selenium
concentrations exceeded the 85th percentile at six of seven stations; the five above plus the
Colorado River at Yuma, AZ. The only station at which selenium concentrations in fish have not
exceeded the 85th percentile was on the Gila River (San Carlos Reservoir, AZ).
Prior to the NIWQPand NCBP studies, studies in the 1930s by the U.S. Department of
Agriculture reported elevated selenium concentrations in water in the upper and lower Colorado,
Gunnison, and San Juan rivers due to irrigation activities"(Anderson et al. 1961). Elevated
selenium concentrations were also reported in water 48 and 112 km southeast of the mouth of the
Colorado River in the Gulf of California. The long-term contamination of the lower Colorado
River basin (Anderson et al. 1961) may have been one of the factors contributing to the
disappearance of endangered fish in the early 1930s as reported by Dill (1944). More recently,
elevated selenium concentrations in water, sediment, and biota in the lower Colorado River basin
documented in a NIWQP study were identified as coming from the upper basin (Radtke et al.
1988, Radtke and Kepner 1990).
Wide spread selenium contamination of the Colorado River basin has been reported. In
the upper basin, Stephens and Waddell (1998) reviewed several NIWQP investigations, data in
the National Water Data Storage and Retrieval System of the USGS, DOl Floodplain Habitat
Restoration Program, and contartJinant assessment reports of the USFWS, and reported that
selenium was present at concentrations harmful to fish and wildlife at several locations in the
Green River basin, UT, including Ashley Creek, Anderson Bottom in the Canyonlands area,
Desert Lake Waterfowl Management Area, Escalante Ranch, Sheppard Bottom in Ouray NWR,
Stewart Lake, Pariette Wetlands, and the Price and Yampa rivers. Busseyet al. (1976) measured
10 inorganic elements in various fish tissues collected from Lake Powell and concluded that only
selenium was elevated to concentrations of concern from a human consumption standpoint. In
muscle tissue, selenium concentrations were 12.2 JLglg in largemouth bass (Micropterus
saZmoides) and 16.8 JLglg in black crappie (Pomoxis nigromacuZatus), which were higher than
the proposed toxic threshold (8 JLglg) for adverse effects in fish (Lemly 1996b). Selenium
concentrations, however, were 6.4 JLglg in walleye (Stizostedion vitreum).
Hamilton (1998) reviewed similar sources plus university studies primarily from the

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