An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

Using CAST to Develop Implementation Plans that Meet Loading Targets in the Chesapeake Bay Watershed

Rich Batiuk, Associate Director for Science, Analysis and Implementation, Chesapeake Bay Program, U.S. Environmental Protection Agency
Olivia Devereux, Environmental Scientist, Devereux Environmental Consulting

The Chesapeake Assessment Scenario Tool (CAST) allows users to run model simulations online for any portion of the 64,000 square mile, six-state watershed. This webcast will demonstrate CAST and highlight how the tool is being used by counties, states, watershed groups, and others for total maximum daily loads (TMDLs), nonpoint source pollutant management, and municipal stormwater programs across the Chesapeake Bay basin. Lessons learned from developing the online load estimator for local planners can be applied to watershed programs nationwide.

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.