Cheney reservoir is a major water supply for the city of Wichita, Kansas. Elevated phosphorus and sediment inputs to the reservoir have caused algal blooms and resultant foul taste and odor problems in the drinking water. Possible sources of this phosphorus could be runoff and erosion from agricultural fields, livestock waste, wildlife, household septic systems, and small town waste systems. This watershed is classified as 99% agricultural with a wide diversity of farming and ranching practices, crops, rainfall, soil types, and topography. In the mid 1990s a citizen's task force was organized to assist producers through cost sharing the implementation of best management practices (BMPs). Implementation of BMPs is voluntary, which may not result in BMP implementation in fields at high risk for nutrient and sediment loss. The objectives of this study are to identify locations in Cheney Lake watershed at high risk of nutrient and sediment loss and evaluate the spatial relationship between BMPs and these locations. Potential for sediment and associated nutrient losses was determined by computing erosion with the revised universal soils loss equation (RUSLE) in a geographical information system (GIS) for the entire 2430 km² watershed. Erosion losses were determined with land cover from 1997 land-use information. A database of BMPs was compiled to evaluate the spatial relationship of BMPs to the locations identified as high risk for losses. Since the mid 1990s, BMPs have been implemented on 17% of the combined crop, pasture, and range land area consisting of 39 different types of conservation practices. The top BMPs are nutrient management planning, terraces, household waste systems, and conservation tillage consisting of 18, 14, 13, and 8% of all BMPs implemented respectively. Information from this study will help local agencies identify critical areas requiring additional BMP implementation, thereby improving the protection of Cheney Lake.