The Agricultural Nonpoint Source Pollution Model (AGNPS), which was developed by Agricultural Research Service, was used as a test model for assessing nonpoint source pollution. The model has runoff, erosion/sedimentation, and water quality components. Input data were obtained from three main data sources. The first source was the GIS databases, which include data on soil, land use, streams and water bodies, farm boundaries, monitoring locations, and land management practices. The second source was digital elevation model (DEM) data, which can be used to generate slope and drainage directions and to provide a three-dimensional display of the outputs in the watershed. The third data source was remote sensing data, which included satellite images and scanned aerial photographs. The approach was tested with two Illinois watersheds and the results indicated that this approach was technically and economically feasible.