This report presents an evaluation of nonpoint source problems affecting the United States Great Lakes and estimated costs for a range of remedial control programs. Consideration of potential critical problems was limited to six areas: in the urban sector, stormwater runoff and combined sewer overflows, construction site runoff and runoff controls for new developments; in the agricultural sector, erosion and sedimentation, and animal waste disposal; as a special problem, on-site waste disposal. Data was collected in places considered potential contributing areas (PCA), those portions of the drainage basin from which contaminants associated with land use activities could reasonably be expected to enter the Great Lakes.