Groundwater contamination from septic system effluent, and the potential transport of selected effluent-derived contaminants to adjacent coastal waters were assessed in the watershed of Buttermilk Bay, a Massachusetts coastal embayment. Groundwater bacterial densities and nutrient concentrations were measured at four septic system sites, as well as upgradient and downgradient of a densely populated sub-basin of the bay.;High densities of fecal coliform, Clostridium perfringens, and enterococcus were observed in effluent samples (10;Nitrate was the only nutrient species consistently found above background levels in groundwater from the downgradient edge of the sub-basin (median = 313... |