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<br />,,".;" <br /> <br />0013 <br /> <br />The inorganic chemical constituents discussed in this report were <br />analyzed by two laboratories using methods described by Fishman and Friedman <br />(1985). After a large volume of water was collected from the reservoir (a <br />minimum of 4 L), numerous subsamples were taken using a churn splitter. These <br />subsamples were treated and preserved onsite using methods described in Feltz <br />and others (1985), except that samples treated onsite for analyses of nitrogen <br />by the Pueblo Board of Water Works Laboratory were not preserved with mercuric <br />chloride in order to avoid interference effects. Water samples sent to the <br />Pueblo Board of Water Works Laboratory were analyzed for turbidity, major <br />ions, dissolved and total nitrogen species, and dissolved and total <br />recoverable trace elements. The U.S, Geological Survey National Water-Quality <br />Laboratory analyzed samples for sulfate, dissolved and total phosphorus <br />species, radiochemical constituents, and total-organic carbon. In addition, <br />the U.S. Geological Survey National Water-Quality Laboratory analyzed all <br />constituents when samples were split with the Pueblo Board of Water Works <br />Laboratory for quality-assurance purposes. Analyses for radiochemical <br />constituents were made using methods developed by Thatcher and others (1977). <br />Total organic carbon was analyzed using methods described by Wershaw and <br />others (1983). The reader should note that concentrations of cadmium, lead, <br />and silver reported greater than the analytical detection level have been <br />regarded as questionable by the Colorado Department of Health (1989, written <br />common.) as a result of a comparison of these data to data analyzed by the <br />Colorado Division of Wildlife from samples collected from the Arkansas River <br />upstream from Pueblo Reservoir. <br /> <br />The less precise methods used in this study for determining <br />concentrations at or near the detection level for cadmium, lead, and silver, <br />as compared to the methods used by the Colorado Division of Wildlife, is <br />acknowledged. However, the analytical methods used for analyses of these <br />trace elements were appropriate for the purposes of the study and for <br />evaluating water quality for municipal use. <br /> <br />During October 1987, sediment cores were collected from 23 reservoir <br />sites by using a 4-ft-long, weighted, stainless-steel 2-in. corer that <br />contained a plastic sleeve. The sediment cores were subsampled at the 0-2 cm <br />depth interval and the 4-6 cm depth interval. The subsamples were air dried, <br />sieved, and hand ground with a mortar and pestle. These samples were then <br />analyzed for total-recoverable concentrations of selected constituents by the <br />Pueblo Board of Water Works Laborstory. A subset of the sediment core <br />samples was analyzed by the U.S. Geological Survey Geologic Division <br />Laboratory for total concentrations of selected constituents_. <br /> <br />Biological samples were collected for analyses of phytoplankton, <br />chlorophyll a, and zooplankton. Biological analyses were done by Chadwick and <br />Associatesl of Littleton, Colorado. Phytoplankton samples were collected from <br />a single depth near the reservoir surface by using a 4-L, nonmetallic, <br />2-ft-long, water-sampling bottle. Periodically, samples were collected at two <br />other discrete depths in the euphotic zone, and a .composite sample of the <br />three discreet samples was made. Phytoplankton samples were preserved in a <br />37-percent formaldehyde solution. Phytoplankton densities are reported in <br />cells per milliliter. <br /> <br />lUse of the firm names in this report is for identification purposes <br />only and does not constitute endorsement by the U.S. Geological Survey. <br /> <br />5 <br />