The Chesapeake Assessment Scenario Tool allows users to rapidly develop scenarios with varying best management practices. Users can compare among scenarios to select the practices that reduce the most pollution, are most cost-effective, and target these practices to the highest impact areas. Scenarios can be used for TMDL Watershed Implementation Plans, Milestones, or for local planning purposes. Output includes nitrogen, phosphorus, and sediment loads from all sectors and sources, acres of each BMP, and costs for the scenario.