MS4 Permit

The Town of Wellesley is responsible for over 130 miles of drain pipe, 4,200 catch basins, 400 outfalls, 2,200 drainage manholes, and 28 drainage connections with other communities. In addition, the Town’s drainage system is comprised of public and privately-owned green infrastructure systems, including constructed wetlands, dry detention basins, infiltration systems, and bioswales. The Town is divided into 10 primary watersheds, all of which are eventually discharge to the Charles River. 

To protect the environment and public health and safety, and to ensure the proper and safe operation of the municipal drainage system, the Town is responsible for administering stormwater requirements contained in federal and state permits and regulations.

The Massachusetts Small Municipal Separate Storm Sewer System (MS4) General Permit authorizes the Town to discharge stormwater to waters of the United States. The permit is jointly overseen by the U.S. Environmental Protection Agency (EPA) and Massachusetts Department of Environmental Protection (MassDEP) and falls under the National Pollutant Discharge Elimination System (NPDES) program. Established in 2003, the permit was reissued in 2016 and aims to improve water quality in surface waterbodies.  In order to comply with the permit, the Town must comply with six Minimum Control Measures (MCMs), as well as additional controls for phosphorus and other pollutants:


Town of Wellesley Drainage System (click to view a larger image)Town of Wellesley Drainage System (click to view a larger image)

MCM 1

MCM 1 - Public Education and Outreach

The Town regularly sends out educational messages to four target audiences: residents, industry, commercial, and construction. The purposes of these messages is to provide information on stormwater and how to implement best management practices.  Educational resources can be found at the Town’s Ways You Can Help page or by visiting Think Blue Massachusetts, a statewide educational campaign.

Touch A Truck


MCM 2 - Public Involvement and Participation

We all have a responsibility to practice good stormwater best management practices and be stewards of a shared natural resource. The public is welcome to provide input in the development and implementation of the Town’s MS4 permit, as well as contribute to stormwater-friendly events such as clean-ups or raising awareness. If you have comments on the program or are looking for ways to contribute, please contact dpw@wellesleyma.gov.

MCM 3

MCM 3 - Illicit Discharge Detection and Elimination Program

Illicit discharges are any non-stormwater substances within a drainage system. These discharges are not allowed by the Town bylaws and can contribute large amounts of pollutants to local waterbodies. Examples of illicit discharges include connections from sewage or washing machines and dumping of hazardous materials or pet waste into catch basins.  To identify and remove illicit discharges, the Town has implemented a methodical water quality sampling and inspection program.  If you are aware of an illicit discharge, please report it to dpw@wellesleyma.gov or (781) 235-7600 ext. 3311.

MCM 4

MCM 4 - Construction Site Stormwater Runoff Control

Soil erosion and improper disposal of construction materials pose a threat to water quality when they are allowed to enter the drainage system. Based on the type and size of the project, the Town requires that erosion and sediment controls are placed on construction sites until final stabilization is achieved.

MCM 5

MCM 5 - Post Construction Stormwater Management

To protect the quality of stormwater discharges after construction on new development or redevelopment has been completed, the use of low impact development techniques or the retention and treatment of stormwater is often required. These best management practices (BMPs) typically focus on protecting beneficial natural resources and/or the use of green infrastructure.

MCM 6

MCM 6 - Good Housekeeping

The Town implements good stormwater housekeeping practices in municipal operations to prevent pollution from entering the drainage system. This includes cleaning catch basins, sweeping streets, regularly inspecting municipally-owned infrastructure, and implementing standard operating procedures for handling with common stormwater pollutants.

additional pollutant controls

Additional Pollutant Controls

In addition to the six minimum control measures, Wellesley is required to implement controls for additional pollutants including bacteria, sediment, and phosphorus. Of these, phosphorus poses the largest and most complex challenge. Phosphorus is a nutrient that acts a fertilizer for vegetation. When too much phosphorus is present, excessive vegetation growth can result. This can lead to a host of issues in waterbodies including noxious algae blooms, dominance of invasive species, and decrease in habitat quality. To address phosphorus the Town will be implementing a Phosphorus Control Plan, a long-term strategy that identifies and acts on opportunities for increased good housekeeping practices and implementation of green infrastructure to reduce phosphorus loads to waterbodies.

Below are documents related to Wellesley's coverage under the MS4 permit. Additional permit documents, such as those required under the six minimum control measures, may be requested at dpw@wellesleyma.gov