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 This website is no longer updated and links to external websites and some internal pages may not work.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 »

Impaired Waters and TMDLs

Pilot TMDL Applications Using the Impervious Cover Method

This report provides a description of the Impervious Cover (IC) method and tests its feasibility as a Total Maximum Daily Load (TMDL) development tool using watersheds nominated by five New England States. In the report, we describe the IC method and apply it to complete a set of seven TMDL allocations for impaired watersheds throughout New England. EPA Region I has identified the IC method as a potentially useful, innovative TMDL approach for water bodies impaired by stormwater. This work has been conducted by EPA Region I as part of an initiative to select and apply scientifically appropriate and resource efficient methods to complete TMDL allocation projects.

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