Stormwater Management

Town of Somerset Stromwater Management Plan and Illicit Discharge Detention & Elimination (IDDE) Plan

Each Community with a municipal separate storm sewer system (MS4) in designated urbanized areas must develop a Stormwater Management Program (SWMP) That will guide its acitivities under the 2016 MS4 general permit. All documents are available for review and coment.

Comments on the plan may be submitted in the following ways:

  • In writting - 140 Wood Street, Somerset, MA 02740 Attention: Nancy Durfee, Town Planner
  • Phone 508-646-2809

Documents and information may be downloaded in PDF or HTML format using the links provided below. Requests for alternative formats may be directed to Nancy Durfee by calling 508-646-2809, or by email at

Illicit Discharge Detection & Elimination (IDDE) Plan:

Town of Somerset Stormwater Management Plan:


Stormwater is water originating from a rain event or snowmelt. Stormwater runoff occurs when the ground is unable to absorb all of the water. Impervious surfaces (such as buildings, driveways, parking lots, sidewalks, roads, and even compacted gravels and soils) prevent most of the runoff from infiltrating into the ground. As such, the runoff is often directed into physical drainage systems (such as catch basins), and then discharged into local rivers, streams, and other water bodies.


As the stormwater runoff flows, it picks up pollutants (such as fertilizer, oils, salt, sediment, and trash), carries them into those drainage systems, and eventually into our local water bodies. These pollutants can cause algae blooms among other aesthetic, health, and environmental issues. Unlike wastewater, stormwater runoff is often untreated or only pretreated before they are discharged into our local water bodies. Therefore, it is very important that we work as a community to keep our stormwater clean.


The Highway Department manages the Town’s storm drainage system, also known as a Municipal Separate Storm Sewer System (MS4). The Town is authorized to discharge stormwater through the Phase II National Pollutant Discharge Elimination System (NPDES) General Permit for Stormwater Discharges from Small MS4s in Massachusetts. The U.S. Environmental Protection Agency (EPA) oversees the NPDES program. To comply with the permit, the Town must follow six Minimum Control Measures (MCMs):

  • 1. Public Education & Outreach: Provide educational material about stormwater to four audiences (residents, industry, commercial, and construction). The purpose of the educational material is to provide the targeted audience information about stormwater and how their actions may impact it.
  • 2. Public Participation: Provide an opportunity for the public to participate in the Town’s Stormwater Management Program (SWMP).
  • 3. Illicit Discharge Detection and Elimination: Find and eliminate sources of non-stormwater discharges (e.g. sewage) from the storm sewer system. Part of this requirement includes development of a system wide storm sewer map:
  • 4. Management of Construction Site Runoff: Adopt an ordinance and procedures for site plan review as well as erosion and sediment control on construction sites that disturb one or more acres of land.
  • 5. Management of Post-Construction Site Runoff: Address stormwater runoff from new development and redevelopment projects that disturb one or more acres of land. The goal of this measure is to try to management stormwater where it falls and retain it on site. This control measure encourages the use of low impact design techniques and requires the retention or treatment of runoff on site using green infrastructure practices.
  • 6. Good Housekeeping in Municipal Operations: Implement good housekeeping practices in municipal operations such as vehicle maintenance, open space, buildings and infrastructure. The permit requires street sweeping twice per year, optimization of catch basin cleaning, and pollution prevention at the Highway Garage.


Lawn and Garden Tips to Help Curb Stormwater Pollution

  • Test the sole first to understand pH and fertilizer needs
  • Leave grass clippings to fertilize the lawn naturally
  • DON'T trash grass clippings and leaves
  • Use leaves as mulch to boost soil health
  • Water once a week in the morning
  • Adjust your mower to cut your grass 2" to 3" tall
  • Keep your equiment blades sharp
  • DON'T mow wet grass
  • If you need to fertilize, use according to package instructions
  • Know your state and local regulations. Limit use of phosphorous and nitrogen in lawn care.

Under Massachusetts law, only apply fertilizer with phosphorus if: A soil test shows that phosphorus is needed; or during the first growing season for a newly established lawn. Contact the UMass Cooperative Extension Soil Nutrient Testing Laboratory to learn how to conduct a routine soil test:

Business owners and residents can do their part to keep Massachusetts' waterways clean.

Other links/resources to lawn care education: &