NPDES-MS4 - National Pollutant Discharge Elimination System - Municipal Separate Storm Sewer System 

What is Stormwater?

Stormwater is water that runs off impervious surfaces such as rooftops, paved roads, driveways and parking lots. Stormwater carries sediment and surface pollutants such as petroleum products, litter/trash, phosphorus and nitrogen. Stormwater is washed down storm drains. The vast drain piping network carries the stormwater into one of the many brooks or ponds in the City where it ultimately ends up in the Sudbury River or the many outfall locations in the town.

Why is Stormwater Runoff a Problem?

Stormwater can pick up debris, chemicals, dirt, and other pollutants and flow into a storm sewer system or directly to a lake, stream, river, wetland, or coastal water. Anything that enters a storm sewer system is discharged untreated into the waterbodies we use for swimming, fishing, and providing drinking water.
Here is something we could all benefit from: Understanding stormwater and what it means in Massachusetts.

Town of Ashland manages the Town's 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 all small MS4s. The United states EPA (Environmental Protection Agency) oversees the NPDES Phase II pemritting program. In order to comply with the program, the Town must follow six Minimum Control measures, which are implemented through a series of Best Management Practices (BMPs). Click on the links below for more details.

 1. Public education and outreach: 

 2. Public involvement and participation
 3. Illicit discharge detection and elimination
 4. Construction site stormwater runoff control
 5. Post-construction stormwater management
 6. Pollution prevention and good housekeeping

Here is more information from the State's EPA website about the permit.

Click here for frequently asked questions about stormwater and how it is a necessary and important utility to maintain.

Currently there are no events planned. We will update this webpage as and when we plan to host events and public info sessions.

Email: to reach the Stormwater Advisory committee with any questions or if you would like to volunteer to be part of this committee.