Open-File Report 2006–1350
U.S. GEOLOGICAL SURVEY
Open-File Report 2006–1350
The Lake Roosevelt National Recreation Area is heavily contaminated from trace elements discharged to the Columbia River from mining activities. A number of studies have reported elevated contaminant concentrations in Lake Roosevelt sediments (Johnson and others, 1990; Bortelson and others, 2001; Majewski and others, 2003; Cox and others, 2005) and in fish (Munn and others, 1995; EVS Consultants, 1998; Munn, 2000). In 1994, the U.S. Geological Survey (USGS) reported that concentrations of cadmium, copper, lead, mercury, and zinc in sediments were elevated to levels greater than biological impairment criteria in surficial sediments (Bortelson and others, 2001).
Lake Roosevelt was formed on the Columbia River by Grand Coulee Dam, which was constructed in the late 1930s and early 1940s to supply irrigation water, control flooding, and produce hydroelectric power. Lake Roosevelt is the largest reservoir by volume in Washington, and one of the largest in the Nation in total storage. Lake Roosevelt is in north-central Washington and extends 217 km upstream of the dam, to within 24 km of Canada. The surface area of the lake is 324 km2, with a full-pool elevation of 393 m. The stage level of the lake varies as much as 24 m annually due to operation of Grand Coulee Dam, with a mean annual water retention time of about 40 days, which varies substantially depending on reservoir management. The average depth is 36 m and maximum depth 114 m. Major tributaries include the Colville River, Kettle River, Spokane River, and Sanpoil River. Additional physical data describing Lake Roosevelt and the upper reach of the Columbia River in the United States are provided by Bortleson and others (2001).
The upper Columbia River and Lake Roosevelt are major recreational and economic resources that draw between 1 and 1.5 million visitors each year. A large attraction is the sport fishery, which includes walleye (Stizostedion vitreum), rainbow trout (Oncorhynchus mykiss), kokanee (Oncorhynchus nerka), yellow perch (Perca flavescens), and smallmouth bass (Micropterus dolomieu), as described by McDowell and Griffith (1993). Contamination of fish from Lake Roosevelt was discovered in the early 1980s, when elevated concentrations of trace elements were found in fish collected from Lake Roosevelt near Grand Coulee Dam (Lowe and others, 1985). In a review of the literature, Serdar (1993) reported that several studies had documented elevated concentrations of trace elements, including mercury, in fish from Lake Roosevelt.
The elevated metal concentrations in Lake Roosevelt have been attributed to the transport of metallurgical waste and slag from a lead-zinc smelter in Trail, British Columbia, Canada (Bortleson and others, 2001). Since 1900, the smelter has discharged slag into the Columbia River at a rate of about 360 metric tons per day in recent years (Cominco Metals, 1991). In addition, decades of discharge of liquid effluent from the smelter in British Columbia contributed most of the zinc, lead, and cadmium detected in a recent sediment-coring study of Lake Roosevelt (Cox and others, 2005). Currently, the smelter discharges trace elements through its wastewater system. Other sources of trace elements in Lake Roosevelt include the Spokane River, which transports trace elements from mining areas around the Coeur d’Alene drainage (Yake, 1979), and additional historical mining activities in the region.
The 1992 sediment-quality assessment by Bortelson and others (2001) also included laboratory sediment bioassays. Lethal and sub-lethal effects were observed in laboratory toxicity tests with two aquatic organisms (Hyalella azteca, an amphipod, and Ceriodaphnia dubia, a water flea) exposed to bed sediments collected from near the International boundary and from some sites in Lake Roosevelt. The survival or reproduction of at least one, and commonly both, of the organisms was adversely affected by sediments collected from the free-flowing reach of the Columbia River entering Lake Roosevelt.
The bioavailability of metals in sediments has long been an issue in ecotoxicology (Luoma, 1983). Large differences in toxicity have been reported from sediments with similar metal concentrations but different physical or chemical parameters (for example, grain size, redox conditions, total and dissolved organic carbon, sulfide content, mineralogy, or hydrology). Early efforts to characterize metal availability in sediments were focused on applying a series of treatments with increasingly stronger chemical severity to the sediment prior to elemental analysis and quantification. This approach, referred to as sequential selective extraction, attempts to identify which and how much of particular metals are associated with particular sediment fractions, usually operationally defined by the treatments used. These approaches have been the subject of several reviews (Luoma, 1983; Tack and Verloo, 1995; Filgueiras and others, 2002).
U.S.
Department of the Interior | U.S. Geological
Survey
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