This report deals with the impact of some waste disposal practices on Great Lakes water quality. Sanitary landfilling, processed organic waste (sewage sludge) disposal on agricultural lands, land irrigation from wastewater lagoons and private waste disposal (septic- tank systems) were identified for investigation in the PLUARG's 1974 Detailed Study Plan. These studies were designed to provide information on the impairment of receiving waters, both surface and ground waters by any effluent/leachate generated as a result of these land-use practices and to provide an assessment of the impact on Great Lakes water quality. In addition, monitoring of wastewater discharges from point sources was undertaken to determine the magnitude and significance of pollutant contributions from direct municipal and industrial discharges with respect to those from diffuse or non point-source contributions in the Grand River and Saugeen River pilot watersheds.