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~. downstream of the discharge, lowering the downstream EPT/C ratios. Macroinvertebrate data <br />' exhibit high variability, with the standard deviations increasing with an increase in mean <br />values. <br />2. No appreciable differences were noted between upstream and downstream physical <br />conditions, with the exception of increased amotmts of silt observed downstream of Sanborn <br />Creek. <br />3. The dischazge plume was detectable in field measuremenu and water samples for several <br />hundred meters downstream. Water quality conditions were near ambient 600 m downstream. <br />4. Although there is a detectable shift in the macroinvertebrate community composition, we <br />believe that the discharge from the Sanborn Creek Mine has a m;n;mal effect on stream <br />macroinvertebrates in general, that the discharge has little, if any, effect on the overall food <br />base for fish, and that the use of the river for fishing has not been impatred. <br />REFERENCES <br />Colorado Department of Highways, 1978, Final Environmental Impac! Statement, Hotchkiss to <br />Paonia Darn. Project RS-133(5). Prepazed by Colorado Department of Highways in <br />cooperation with the U.S. Department of Transportation and Federal Highway <br />Administration. <br />• Merritt, R.W., and K.W. Cnmminc (Ed.), 1984, An Introducrion to the Aquatic Insects of <br />North America, 2nd Ed. Kendall Hunt Publishing Co., Dubuque IA. <br />Pennak, R.W., 1978, Fresh Water Invenebrates of the United States, 2nd Ed. John Wiley and <br />Sons, N.Y. <br />USEPA, 1989, Rapid Bioassessment Protocols for Use in Streams and Rivers: Benthic <br />Macroinvenebrates and Fish. EPA/440/4-89/001. <br />USEPA, 1990, Macroinvertebrate Field and Laboratory Methods forEvaluating the Biological <br />Integrity of Surface Waters. EPA/600/4-90/030. <br />USGS, 1992, Water Resource Data, Colorado, For Water Year 1992. USGS Water Data <br />Report CO-92-2, USGS Water Resource Division, Lakewood, CO <br />Ward, J.V., and B.C. Kondratieff, 1992, An Itlustrated Guide to the Mountain Stream Insects <br />of Colorado. University Press of Colorado, Niwot, CO. <br />Woodling, J., 1985, Colorado's Little Fish: A Guide to the Minnows and Other Lesser Known <br />Fishes in the State of Colorado. Colorado Division of Wildlife. <br />', 22 <br />• <br />