Limnological studies of five reservoirs in the Salt Valley Watershed District (eastern Nebraska) were initiated to determine existing trophic conditions, estimate eutrophication rates, if possible, by measuring changes in several parameters, identify sources of nutrient inputs, and evaluate preventative and remedial measures. Water samples were analyzed for dissolved oxygen, temperature, underwater light intensity, alkalinity, pH, hardness, dissolved and suspended solids, iron, COD, phosphates, ammonia, nitrate and organic nitrogen, chloride, sulfate, and turbidity; algae identified, and primary production determined. Runoff waters impounded in the reservoirs contain sufficient nutrient salts to support abundant growths of aquatic plants. (Author)