Welcome to the Chesapeake Assessment Scenario Tool
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CAST is based on the Watershed Model version Phase 5.3.2. The Phase 6 version is available here. The Phase 5.3.2 version of the Watershed Model and CAST may continue to be used until the Bay TMDL 2017 milestone assessment and progress review are completed. This is expected in Spring 2018, at which time CAST will no longer accept new scenarios or changes to inputs. Scenario data can be downloaded then imported to the Phase 6 CAST.

The Chesapeake Assessment and Scenario Tool (CAST) allows users to rapidly develop scenarios with varying best management practices.

Output includes nitrogen, phosphorus, and sediment loads from all sectors and sources, acres of each BMP, and costs for the scenario for any area in the Chesapeake Bay Watershed. These loads are consistent with the Chesapeake Bay Program’s Watershed Model. CAST also provides inputs to the Chesapeake Bay Program computer models.

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.

FAQs about the transition to Phase 6