Official websites use .gov
A .gov website belongs to an official government organization in the United States.
Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.
This is not the current EPA website. To navigate to the current EPA website, please go to www.epa.gov. This website is historical material reflecting the EPA website as it existed on January 19, 2025. This website is no longer updated and links to external websites and some internal pages may not work. More information »
The Merrimack River watershed is the fourth largest watershed in New England, encompassing 5,010 square miles.
Stormwater runoff is generated from precipitation that does not soak into the ground. The runoff picks up pollutants that can harm our waters.
Water quality monitoring is a crucial aspect to protecting and understanding water resources.
