WHEN BACTERIA ATTACKS: KEUKA OUTLET, NEW YORK

As the largest by volume and deepest Finger Lake of New York State, Seneca Lake provides 100,000 people with Class AA drinking water and is a main stimulant of the local tourist economy. As the most dependable water resource in the region, the importance of understanding natural and human impacts is essential. Here we expand on earlier research that focused on bacteria and nutrient concentrations, fundamental water quality indicators, through segment analysis of Keuka Outlet, a major tributary of Seneca Lake. With aging sewage treatment systems and significant (~75%) agricultural land use, this watershed is ideal for studying the effects of human activity on our vital natural resource.

In 2005, water was collected and analyzed weekly from seven sites during the early summer. Samples were analyzed for total coliform and E. coli bacteria using an EPA approved Hach Method #10029, that used a m-ColiBlue24 broth and reported as colony forming units (CFUs)/100mL. In addition, water samples were filtered at 0.45µm and the filtrate analyzed for dissolved nutrients, silica, phosphate and nitrate following standard limnological techniques using a spectrophotometer. Total Suspended Solids (TSS) of the samples was determined by the weight of the residue on the filters. Hardness, alkalinity, pH, dissolved oxygen, conductivity, temperature, and stream discharge were also measured on site.

The data reveals two results: a major rain event on June 16^th and a potential pollutant source in the segment analysis. Four parameters reveal significant increases in concentration in conjunction with the rain event on the 16^th: dissolved silica, phosphate, TSS and E. coli concentrations. These peaks are well above average and in step with TSS suggesting that the large concentrations were due to the runoff event. Segment analysis reveals increases in E. coli, nitrate and phosphate concentrations between Fox Mills and Milo Mills, possibly due to failing septic systems. Dissolved silica concentrations decrease downstream, possibly reflecting uptake by benthic algae. The two remaining parameters, discharge and total coliform, show no discernable temporal or spatial trends although total coliform concentrations surpasses EPA standards for recreational water use during the 16^th rain event at four of the seven sites.