Milton’s MS4 Initiative


MS4: Municipal Separate Storm/Sewer System

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 Milton’s MS4 is regulated under the EPA Clean Water Act (CWA) and requires a permit for discharges to the environment.

These educational brochures have been developed by NHDES, UNH Cooperative Extension, and the USEPA and that they have been adapted for the Town of Milton to help inform the community about best practices relating to water-quality and the management of storm-water runoff.

The following handouts/brochures are available below. These can be downloaded and printed:

  • Best practices for Septic Tanks
  • Managing Yard Waste #1
  • Managing Yard Waste #2
  • Pet Waste
  • Lawn Care: Watering and Fertilizing