Nonpoint source pollution is becoming a larger contributor of freshwater organic nutrient waste in surface and groundwaters. Agriculture and municipal wastewater management systems are often named as contributors to nutrient pollution, however, on-site sewage management systems also contribute significantly to freshwater pollution. A typical urban watershed was selected in which macroinvertebrate communities in eight first order streams were monitored along with water quality. Water samples taken bimonthly and analyzed for nitrates, conductivity, and other parameters, along with macroinvertebrate assemblage data, were correlated with measures of septic system density within each stream. In addition, a dosage trial was also executed to explore the effects of nitrate concentration on macroinvertebrates. Results p=0.05, septic system density does have an effect on water quality and macroinvertebrate assemblage. While septic systems in this watershed were functioning properly, streams with municipal sewer input and wastewater treatment plant input had impaired water quality.