ABSTRACT
Eutrophication has been identified as the most pressing water quality problem in the Long Island Sound due to excessive nutrient loading from land-based point and non-point sources and from atmospheric deposition. A three-year Water Quality Monitoring Program was initiated in January 1997 by the Westchester County Department of Planning and New York State Department of Environmental Conservation (NYSDEC) to determine the nutrient loads delivered to Long Island Sound from the two largest watersheds in lower Westchester County via Mamaroneck and Blind Brook rivers. Baseline and storm events were studied in an attempt to obtain representative samples that included both dry and wet weather conditions. Water temperature, pH, conductivity, dissolved oxygen and flow rate were monitored in the field, whereas turbidity, total suspended solids, total coliform, fecal coliform, total nitrogen, total Kjeldahl nitrogen (TKN), nitrate, nitrite, ammonia, total phosphorus, and orthophosphate were analyzed. Annual input of nutrients from the Mamaroneck and Blind Brook watersheds into the Long Island Sound were determined using water concentrations data and river flows. Although the Mamaroneck and Blind Brook Wastewater Treatment Plants are still the main contributors of nitrogen loading, 217 tons and 29 tons from both MWWTP every year respectively, the data show that non-point sources from both watersheds contribute significant loads amounting to 70 tons and 40 tons, respectively. In Spring 2000, rainfall samples collected in two locations in the watersheds during three storm events show that total nitrogen loads from atmospheric sources could account for 14% and 18% of the total loads measured in Mamaroneck River and in Blind Brook respectively.
