BACTERIAL AND NUTRIENT WATER QUALITY SURVEY OF THE KEUKA OUTLET, SENECA LAKE WATERSHED, NY

Seneca Lake is the largest and deepest Finger Lake of New York State. The lake provides over 80,000 people with Class AA drinking water and is the focal point for the local tourism economy. Recently, aging municipal and residential waste water treatment systems and an influx of Concentrated Animal Feedlot Operations (CAFOs) have surfaced as emerging concerns for water quality. Preliminary Coliform and nutrient analyses of major tributaries of Seneca Lake during the summer 2003 indicated that Keuka Outlet, a watershed with aging treatment systems and significant agricultural land use, is ideal for additional study.

Here, we report on a segment analysis study to investigate potential sources of contaminates to the Outlet. Water samples were collected on five dates at four different sites along the length of the Outlet during the fall of 2003 and analyzed for Total, E. coli, and Fecal Coliform bacteria using EPA approved Hach procedures. Water samples were diluted (10x), filtered, and incubated in a down-turned Petri-dish on an absorbent pad saturated with m-ColiBlue24 and m-FC broths at 35oC for 24 hours. Colony forming units (CFUs) were viewed and counted under a low-powered microscope and values were multiplied by the dilution factor to reflect colonies per 100 mL. Other water quality parameters were measured on the same samples and included soluble nutrients (nitrates, phosphates and silica), total suspended solids, hardness, alkalinity, pH, dissolved oxygen, conductivity, temperature and stream discharge.

The results indicate that Coliform and other water quality parameters are within the EPA and NYS DEC standards (2,400 Total Coliform colony forming units per 100 mL, and 10 mg/L for nitrate). The bacterial data do not reveal temporal or spatial trends nor do correlations exist between Coliform concentrations and the other measured parameters. Interestingly, nitrate concentrations increase downstream from below 1 mg/L to 1-4 mg/L between the middle two sites. No obvious and unique source(s) for nitrates is observed in land use and other maps of the watershed, and suggests a focus for future research.