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<br />0023~5 <br /> <br />SAMPLE COLLECTION AND ANALYSIS <br /> <br />Objectives <br /> <br />The general objective of this reconnaissance investigation was to deter- <br />mine if selenium, other trace elements, and pesticides were present in water, <br />bottom sediment, and biota in and downstream from the Uncompahgre Project <br />area. Constituent concentrations were compared to guidelines for environ- <br />mental quality or natural background concentrations. A specific objective was <br />a general reconnaissance to determine if the project area was contributing <br />potentially harmful chemical constituents and compounds to the Gunnison and <br />Uncompahgre Rivers. Another objective was to substantiate the large selenium <br />concentrations previously reported in water, bottom sediment, and fish from <br />Sweitzer Lake. <br /> <br />A standard set of chemical constituents (table 8) for analysis in each <br />medium were developed by the DOl Task Group for use in all irrigation- <br />drainage studies to afford comparability of data among the study areas. At <br />water-quality collection sites, water temperature, pH, specific conductance, <br />and dissolved oxygen were measured. Stream discharge was determined at the <br />sites on the Gunnison and Uncompahgre Rivers and at inflow and outflow sites <br />at Sweitzer Lake. Instantaneous stream discharge was determined at sites <br />with gaging stations from the stage record and from stage-discharge rating <br />tables. Pesticide compounds selected for analysis were based on pesticide <br />usage in each study area. In the Uncompahgre Valley, organophosphate and <br />carbamate pesticides and the herbicide 2,4-D (table 8) were selected based <br />on discussions with agricultural extension agents and farm-supply businesses <br />in the area. <br /> <br />A primary objective of the biological sampling was to identify possible <br />bioaccumulation of contaminants within different trophic levels. Biota <br />selected from lower trophic levels (invertebrates and plants) represent <br />possible food sources for either fish or migratory birds that were most likely <br />to be present at study-area locations. Consistency in species composition of <br />samples among sites was attempted so that direct comparisons of data could be <br />made between areas. Consistency among species could not always be achieved <br />because of habitat variability and because sufficient numbers of organisms <br />for adequate biomass for analysis could not always be collected. <br /> <br />Bird and egg samples of the following species were collected during this <br />study: Canada geese, common mergansers, mallards, blue-winged teal, western <br />grebes, eared grebes, coots, sora rails, Gambel's quail, bobwhite quail, <br />killdeer, red-winged blackbirds, and yellow-headed blackbirds. Fish species <br />collected include: brown trout, rainbow trout, channel catfish, green sunfish, <br />flannelmouth suckers, white suckers, bluehead suckers, carp, round tail chubs, <br />red shiners, speckled.dace, fathead minnows, and mottled sculpin. <br />Invertebrate species collected were crayfish and snails, and various insects. <br />Aquatic plants and filamentous algae samples also were collected. <br /> <br />29 <br />