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Stormwater Spotlight: How Permits Can Protect Your Favorite River

Writer's picture: Lydia OlsonLydia Olson

Part 1: Understanding the MS4 Permit System


storm drain that collects water and pollutants
storm drain that collects water and pollutants

Did you know that every time it rains or snows, water that rushes off roads, driveways, and rooftops carries a dangerous cargo of pollutants straight into our rivers? Stormwater runoff isn’t just dirty water—it’s the one of the biggest sources of water pollution in Massachusetts! The US Environmental Protection Agency (EPA) estimates that nationwide, 10 trillion gallons of untreated stormwater runoff enters US waterways from city sewer systems every year.


But here’s the good news: each of us can help clean up stormwater, and it starts with understanding the problem.


So we’re thrilled to launch a four-part blog series on stormwater. Throughout this series, we’ll explore the fundamentals of stormwater pollution; who regulates it, tools for tackling the problem, and how sewage overflows contribute to the issue. 


Let’s dive in with our first installment on stormwater permitting, also known as the MS4 Permit system. Don’t worry, it is not as scary as it sounds!


What is stormwater, and how does it pollute our rivers?


Stormwater refers to water from rain or snow that is not absorbed by the ground and instead runs off surfaces. In urban landscapes, more of the ground is covered by pavement or other hard surfaces (called impervious surfaces) that rain or snow cannot penetrate. Instead, that water runs along streets and parking lots, picking up pollutants as it moves. Just one inch of rainfall on one mile of a narrow, two-lane road can produce 55,000 gallons of stormwater runoff!

Diagram showing effects of impervious surfaces on runoff and infiltration. Four scenarios from natural ground cover to 75-100% imperviousness.
Diagram showing effects of impervious surfaces on runoff and infiltration

In most systems, stormwater is not directed to a water treatment facility to be cleaned before it reaches a water body. Instead, this polluted runoff flows directly into our rivers and streams, degrading water quality, and sometimes overwhelming local infrastructure, which can then lead to sewage overflows. Contaminants can include nutrients like nitrogen and phosphorus from lawn fertilizer or leaf litter; bacteria from dog or animal waste; salt and other deicing chemicals; heavy metals, and oil/grease from cars and industrial areas. The next time you are out in your neighborhood, see if you can spot impervious surfaces around you- you might be surprised at how much you find!


Who regulates stormwater?


In Massachusetts, stormwater pollution is regulated at the federal level by the EPA with a permit called the Municipal Separate Storm Sewer System General Permit, abbreviated as the MS4 Permit. Most impervious surfaces in Massachusetts are owned by cities or towns, (i.e. roadways), and this permit applies specifically to municipal-, state-, and federally-owned properties in urban areas of greater than 50,000 people that have stormwater infrastructure, and discharge their collected stormwater to a “Water of the United States” as defined by the US Clean Water Act. Any owner or operator of a MS4 must apply to the EPA with a Notice of Intent to discharge, and the EPA reviews the applications and decides what permit requirements will be necessary for each permittee.

Map depiciting areas in Massachusetts covered under MS4 permits. Courtesy of the EPA.
Areas in Massachusetts covered under MS4 permits. Courtesy of the EPA.

What is in an MS4 Permit?


The permit itself tells the organizations regulated by the permit, “the permittees”, how much pollution they are allowed to release into nearby water bodies, and what actions they must take to limit stormwater pollution from their sewer systems. 

Under the MS4 permit, municipalities must implement six minimum control measures to limit the amount of pollution from stormwater that enters water bodies:

  1. Public Education and Outreach

  2. Public Participation

  3. Illicit Discharge Detection and Elimination

  4. Management of Construction Site Runoff

  5. Management of Runoff from New or Redevelopment (after construction)

  6. Good Housekeeping in Municipal Operations

 

How does the MS4 Permit protect our rivers?


As part of the permit, municipalities must have programs, like street sweeping and installing green infrastructure, to reduce both the volume of and the amount of pollutants in stormwater that reach local water bodies. Additionally, public involvement is a key requirement of the permit, so all towns should have ways for residents to get involved in stormwater management, like Adopt-a-Drain programs and leaf collection.


Though the permit has existed since 2003, stormwater pollution remains a problem throughout the state. This is because, while the permit limits stormwater pollution, it does not eliminate it, and in many areas it could limit different types of pollution more strongly. Also, the permit has no penalties if permittees fail to meet the requirements of their permit. Thus, many permittees may not be meeting requirements- mainly due to lack of funding and staff to institute and organize permit conditions. 


Additionally, permittees are responsible for stormwater generated by private properties and institutions, which adds more pollution to sewer systems that municipalities are not equipped to handle. The EPA has recently issued a permit using their Residual Designation Authority (RDA) to cover stormwater specifically from private properties in the Charles, Mystic, and Neponset Watersheds to address this issue, which we will talk about in part II of our stormwater series.


What’s happening with the MS4 Permit now?


The MS4 permit for Massachusetts is currently in the process of being renewed. The EPA has issued a Draft Permit that is currently open for comment until February 20th, 2025. The new permit contains exciting progress, like a restoration plan for the Mystic River, one of the most heavily-urbanized watersheds in Massachusetts. However, because Massachusetts MS4 permits are issued by the EPA, depending on the priorities of the new federal administration, the final permit may not be issued. In that case, the previous permit that was revised in 2020 will go into effect.


The current Draft Permit is exciting because it gives us the opportunity to submit a comment letter that addresses some of the limitations of the Draft Permit, which could help to strengthen the requirements for stormwater pollution elimination and ensure that more permittees are able to meet their permit requirements.


What can you do?


Everyone has a right to clean, healthy water and waterways. The MS4 Permit regulates the amount of stormwater that can be released into waterways and the actions needed to limit stormwater pollution. Change starts with understanding the problem—and taking small steps to be part of the solution. 

You can play a role in shaping the new MS4 Permit by:

  • Attending the EPA's upcoming information meeting and public hearing. It is currently postponed, but you can check this website to sign up for the meeting when it is rescheduled. 

  • Signing up for our bi-weekly e-newsletter, River News & Notes, to be notified of other opportunities/information relating to stormwater!                                                                 

  • Writing your own public comment for the MS4 permit. You can contact your local watershed organization or email our Technical Specialist, Lydia Olson, lydiaolson@massriversalliance.org, for a draft letter to send directly to the EPA. 

  • Get involved with your town’s Stormwater Management Program, or help spread the word on stormwater pollution to your friends and neighbors. Reducing lawn fertilizer in the spring, leaving your leaves on your lawn in the fall, and cleaning out your local storm drains are all easy, inexpensive ways to help reduce stormwater pollution. Little by little, we can collectively do a lot to clean up stormwater!


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Founded in 2007, Mass Rivers works to strengthen statewide river policies in four areas: water quality, streamflow, wildlife habitat, and investment in green infrastructure.

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