ASSESSING IN THE ROLE OF WATERSHED AREA AND LANDUSE ON NUTRIENT AND SUSPENDED SEDIMENT FLUX TO SENECA LAKE, NY

Seneca Lake is the largest of the Finger Lakes in central New York State. It is an ideal natural hydrogeochemical laboratory to study the source and impact of non-point source pollutants. The 29 subwatersheds and drainages (adjacent first order streams) drain a variety of surface areas (from a few to over 100 km2), landuse areas (agricultural, forested and lesser amounts of urban land), bedrock types (Paleozoic carbonates, shales and coarser silicate-rich clastic rocks), soil types and other features. This project investigated the flux of nutrients and suspended solids to the lake.

Over the past 6 years, weekly to biweekly stream discharge and water samples were gathered from the terminus of seven subwatersheds that represent the array of available surface areas, landuse and bedrock in the basin. The fieldwork focused on the late spring and summer months and resulted from coursework, independent study and summer undergraduate research projects. The water samples were filtered and the filtrate analyzed for Soluble Reactive Phosphate (ppb, P), Nitrate (ppm, N) and Total Suspended Solids (mg/L) and complemented with other common hydrochemical parameters (pH, alkalinity, hardness, conductivity, etc. by appropriate field meters and field titration kits).

The results indicate that basin area, agricultural activities and human waste disposal are the primary factors controlling the nutrient and suspended sediment influx to the lake. The average daily fluxes range from 0.4 to 8.4 kg P/day for phosphate, from 5 to 60 kg N/day for nitrate, and from 30 to 900 kg/day for TSS, amoung the sampled streams. The nutrient fluxes are modulated by biological activity within the watershed and the lake.