Pelham Stormwater Management - MS4

This page is provided so the public can easily access Pelham’s Stormwater-related plans, permits, public educational messages and other useful information about protecting our most precious natural resource.

Municipal Separate Storm Sewer System (MS4)


Local drainage systems, whether natural or constructed, are important features that generally carry stormwater runoff away from developed areas to undeveloped areas, waterbodies, and wetlands. Although these drainage systems help to manage stormwater in our built environment, they are also a primary source of untreated pollutants in receiving waters including bacteria, nutrients oil, trash, and many other pollutants. These untreated pollutants in stormwater runoff are defined by the U.S. Environmental Protection Agency (EPA) as “nonpoint source pollution”, meaning that the source of the pollution is not directly attributable to a single spatial point or polluter. Stormwater runoff from streets, parking lots, and lawns picks up and carries contaminants as it moves across the ground surface before entering into local drainage systems.

A municipal separate storm sewer system (MS4) includes the stormwater collection, conveyance, and outfall structures within a city or town. These structures include (but are not limited to) catch basins, drain manholes, culverts, stormwater basins, and swales. As with approximately sixty other municipalities in NH, the Town of Pelham’s MS4 is regulated under the EPA Clean Water Act (CWA) and requires a permit for discharges to the environment.

Stormwater Management Plan
Stormwater Management Plan Appendix AStormwater Management Plan Appendix BStormwater Management Plan Appendix C
Stormwater Management Plan Appendix DStormwater Manatement Plan Appendix EPelham MS4 Stormwater Map