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COEUR D'ALENE LAKE, IDAHO. HYPOLIMNETIC CONCENTRATIONS OF DISSOLVED OXYGEN, NUTRIENTS, AND TRACE ELEMENTS, 1987
Description:
A reconnaissance study of Coeur dAlene Lake, Idaho (17010303) done from May through November 1987 assessed water quality throughout the lake. Particular emphasis was on hypolimnetic concentrations of dissolved oxygen, nutrients, and trace elements. Study results enabled refinement of the sampling protocol in a U.S. Geological Survey research proposal for a large-scale investigation of nutrient enrichment and trace-element contamination problems affecting the 129.5 square kilometer lake in northern Idaho. Hypolimnetic dissolved oxygen concentrations as low as 4.1 milligrams per liter in November and the frequent occurrence of supersaturated dissolved oxygen concentrations from June through August indicated nutrient enrichment. Secchi-disc depths in the lakes central and southern areas were typical of mesotrophic conditions, whereas oligotrophic conditions prevailed in the northern area. Throughout the study, hypolimnetic concentrations of total recoverable zinc exceeded chronic and acute toxicity criteria for freshwater aquatic life. Woods, P.F. 1989. USGS Water-Resources Investigations Report 89-4032. U.S. Geological Survey, Boise, ID. 56 pp.