Water-quality reconnaissance of selected water-supply lakes in eastern Kansas

Data collected for 19 public water-supply lakes in eastern Kansas during spring-fall 1983 were statistically analyzed to describe relationships between water-quality constituents and lake and watershed physical characteristics. A large range was observed in mean concentrations of total nitrite plus nitrate nitrogen, total ammonia nitrogen, total phosphorus, total organic carbon, and chlorophyll a and in lake and watershed physical characteristics, such as age, surface area, watershed area, watershed-to-lake surface-area ratio, and average maximum depth. Pesticides were detected in 8 of the 19 lakes. Atrazine and Alachlor were the most commonly detected pesticides. Spearman rank-order correlation analyses showed possible relationships between mean concentrations of total nitrite plus nitrate nitrogen, total ammonia nitrogen, total phosphorus, total organic carbon, and chlorophyll a, and certain lake and watershed physical characteristics. Multiple-regression analysis produced significant relations between mean concentrations of total nitrite plus nitrate nitrogen and percentage of watershed in protected cropland and age of lake (0.62 coefficient of determination), and between mean concentrations of total organic carbon and lake average maximum depth, lake-surface area, age of lake, and watershed-to-lake surface-area ratio (0.76 coefficient of determination). (USGS)