Background: Stormwater and Its Regulation


Stormwater is water that runs off the land when it rains or when snow melts. On landscapes impacted by human development, stormwater carries fertilizer, harmful bacteria, oil, gas, toxic metals, and salt into nearby waterways. Julia Blatt, executive director of the Massachusetts Rivers Alliance, says in the Boston Globe, “Stormwater is the state’s No. 1 pollution problem.”

How stormwater discharge is regulated:

Stormwater is regulated as part of the National Pollution Discharge Elimination System (NPDES), which is part of the body of regulations set up under the Clean Water Act. For municipalities in the more populated parts of Massachusetts (see map below), stormwater discharge is regulated by a system called “MS4,” for “municipal separate storm water systems.”


Under this system, a permit is jointly issued by the federal Environmental Protection Agency (EPA) and the Massachusetts Department of Environmental Protection (MassDEP) to a town such as Acton. This involvement of EPA is unusual; in all but a few states, MS4 permitting is done solely by the state.

Permitted towns must create stormwater management plans, map their stormwater collection systems, monitor outfall pipes, and prioritize cleanup of the most pressing problems. Permits also require public outreach, stormwater recharge, and “good housekeeping” practices, such as storm drain cleaning and street sweeping.

How the MS4 system works in Acton:

Discharges that will flow into to the local storm drain system are regulated under the Town of Acton General Bylaws, chapter U. Basically, the Acton bylaw (“Discharges to the Municipal Storm Drain System”) says that no person or business can discharge anything into the Acton storm sewer system or into the “Waters of the Commonwealth” that isn’t just plain water, and that any large-volume discharges (for example, from a sump pump, or from runoff from a construction site), require a permit from the Town. There are a few exemptions: indirect discharge of pesticides, herbicides, and fertilizer via runoff from lawns or crops is allowed if the chemicals have been used “as intended.” There is a long list of pollutants that are specifically not allowed, including oil and other automotive fluids, animal wastes, and “noxious or offensive matter of any kind.”  A short, pragmatic version of the rules is here, along with a link to the application for a discharge permit. The enforcement agency is the Acton Board of Health.

2017 troubles over revised Massachusetts stormwater permit:

As detailed in a Green Acton News & Updates piece, the NPDES general permit for Massachusetts expired in 2008. The EPA, MassDEP, and various stakeholders negotiated an updated set of regulations, which were finally agreed upon in 2016, and set to become effective on July 1, 2017. However, two days before the intended effective date, EPA announced that the effective date was being postponed for one year, until July 1, 2018. A group of watershed protection organizations, including our local OARS, has sued EPA to get a court order to implement the agreed upon general permit.


  • 1948: The Federal Water Pollution Control Act, the first major U.S. law to address water pollution
  • 1972: the Clean Water Act
  • 1990: NPDES Phase I regulation requires medium and large cities or certain counties with populations of 100,000 or more to obtain NPDES permit coverage for their stormwater discharges
  • 1999: NPDES Phase II regulation requires small MS4s in U.S. Census Bureau defined urbanized areas — including Acton
  • 2003: EPA Region 1 issued the  General Permit for MS4s in Massachusetts
  • 2008: the 2003 General Permit expired, and was continued administratively, while new permitting rules were developed
  • April 4, 2016: EPA issued the new general permit, with an effective date of July 1, 2017
  • June 29, 2017: EPA postponed the effective date for one year, until July 1, 2018
  • September 22, 2017: the Massachusetts Rivers Alliance and nine of its member groups filed a lawsuit in federal district court, asking the court to revoke EPA’s one-year stay of the Massachusetts stormwater permit (MS4), and implement the permit immediately

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