A detailed survey of 2450 dwellings on the shore of Crystal Lake and their waste water systems was carried out by members of the University of Michigan Biological Station Project CLEAR during the September 20 - October 30, 1978 period. This total of 249 homes represents 23% of the total of 1085 homes on the lake shore. From information derived by the survey, it was determined that approximately 76% of the homes on Crystal Lake are used seasonally. The winter population of about 550 easily climbs to 4000 on most summer weekends. The shoreline was divided for purposes of doing the survey into five sections. These were each evaluated individually (NE, NW, W, SW, SE). The important variables calculated for each section were: percentage of septic systems with problems, percentage of septic systems more than ten years old, percentage of septic systems within 50 feet of the lake, percentage of shore line lots with Cladophora (a microscopic algae), and percentage of septic systems meeting current public health regulations. Most of the lake is surrounded by sandy, well-drained soils except for the NE and parts of the SE sections. These two sections also had the largest summer populations and the highest concentrations of Cladophora. Central sewering and land application should be considered for these areas. The NW, W, and SW sections are on better soils, have fewer septic system problems, and less Cladophora. On-site improvements would be necessary however, because more than 60% of the homes do not meet current public health regulations.