Using aerial and LANDSAT data a dynamic land use model of the Nam Pong Basin has been developed. The model simulates erosion that results from conversion of watershed land to alternative uses. Erosion values are passed to a linked reservoir model where they are converted to turbidity levels. Operated together the two models simulate changes in quantity and quality of fish production resulting from increased turbidity levels. Simulation of alternative management scenarios predicts continued increases in sedimentation leading to drastic reductions in fishing income levels. Restrictions on number of fishing families and protection of critical watershed areas are necessary to protect the long-term sustainability of the reservoir fish production system.