A steady increase in the chloride and nitrate content of water in a sand and gravel aquifer of glacial origin in the Cortland, N.Y., area prompted a study to obtain data on the extent and source of these constituents. Chloride concentration in the upper part of the aquifer increased generally from 2 mg/liter in 1930 to 20 mg/liter in 1976, and nitrate concentration (as nitrogen) in the upper part of the aquifer increased from 1 mg/liter in 1930 to an average of 4 mg/liter in 1976. Although the ground water is normally very hard, its quality generally meets State standards for source waters used for drinking. Road salting and farming seem to be the primary cause of chloride increases, although septic systems may be a major source locally. Farm-animal waste, sewage systems, and fertilizers are the major contributors of nitrate to ground water. Flow in the aquifer system in the Otter Creek-Dry Creek basin was simulated with a digital-computer model. The model was calibrated by comparing measured water levels in the aquifer with those determined by the model. The major sources of recharge are from precipitation and seepage from losing reaches of the streams. (Woodard-USGS)
