The Impact of Septic Tank Systems on the Water Quality of Stream Reaches in the Oak Orchard Watershed

Abstract

This study evaluated whether septic fields are a source of nonpoint source pollution in the Oak Orchard watershed. Accurate spatial information on septic fields was combined with hydrography and water quality sampling to identify stream reaches and parts of the shoreline that are most sensitive to septic systems. The regression analysis between septic field density and nitrate concentration shows a weak positive relationship. The regression analysis between number of fields within 200-meters and nitrate concentration also shows a weak positive relationship. The regression analysis between percent cropland and nitrate concentration, and percent cropland and SRP concentration, implies that agriculture does not have as large of an impact on nutrient pollution during the late summer. This study suggests that septic fields do have an impact on nitrate concentrations in the Oak Orchard watershed.