Charles River Watershed Association
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Promote Resilience

Curbing Stormwater Pollution
Stormwater runoff is the largest source of pollution to the Charles River. Stormwater carries phosphorus into the river, causing toxic cyanobacteria blooms, invasive plant overgrowth, and poor habitat conditions. These threats will be significantly exacerbated by our changing climate.
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Massachusetts Municipal Stormwater Permit

An updated stormwater permit (referred to as “MS4” permit, short for “municipal separate storm sewer system”) was issued in 2016 that would protect rivers and streams all across the state by reducing the amount of nutrient pollution, especially phosphorus, entering our waterways. When industry and municipal groups challenged the permit in court, CRWA and Conservation Law Foundation intervened in the appeal to prevent the permit from being weakened. The parties reached a 
settlement in late 2019. Under the new permit, over the next twenty years, cities and towns must reduce phosphorus discharges into the Charles in accordance with what CRWA’s studies have shown is necessary for a truly healthy river. CRWA continues to work closely with watershed communities to implement the requirements of the MS4 permit and ensure compliance. Many of the measures required under the permit will also significantly improve communities’ climate resilience. 

additional resources
  • MS4 Permit Workshop: BATT Tool video recording
  • MS4 Permit Workshop: Managing Stormwater video recording​
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Beyond MS4: Regulating Large Stormwater Polluters under the Clean Water Act

While cities and towns in our watershed are required to manage stormwater under the Clean Water Act, commercial, industrial, and large multi-unit developments (big box stores, universities, etc.) currently do not face the same requirements even though they are a large part of the problem. These properties essentially have a “free pass” when it comes to stormwater, placing more of a burden on municipalities and more pollution in the river.
 
In 2019, CRWA and Conservation Law Foundation formally asked EPA to regulate large properties that are polluting the Charles River with stormwater runoff. Under the Clean Water Act, EPA has what is referred to as “residual designation authority,” which gives the agency the power to require stormwater discharge permits in certain situations, like when the discharges contribute to a violation of water quality standards. In the Charles River watershed, it will be difficult to reduce phosphorus pollution to safe levels, also known as the “total maximum daily load” (TMDL), unless large polluters bear their fair share of the responsibility for managing stormwater. In August 2020, EPA announced that it is gathering input from stakeholders on how to address this issue. CRWA will continue pushing for regulation of these large contributors to stormwater pollution in order to fully restore the health of the Charles.

ADDITIONAL RESOURCES
  • ​CRWA Presentation on Curbing Stormwater Pollution: Regulating Large Stormwater Sources
  • CRWA Fact Sheet
  • EPA's Presentation on Charles River Stormwater Permitting​
  • EPA FAQs
  • City of Cambridge's Resolution in Support
Send Comments to EPA
Charles River Watershed Association
41 West St. Suite 800 Boston, MA 02111
t (617) 540-5650   e charles@crwa.org

​© 2021
Donate
  • About
    • Mission
    • Charles River
    • Staff and Board
    • Employment & Internships
    • Contact Us
  • Our Work
    • Blue Cities
    • Climate Change
    • River Science
    • Advocacy
    • CRWA Projects
    • Project Resources
  • News
    • River Current
    • Press
  • Education
    • Request a Visit
    • Classroom Resources
  • Get Involved
    • Events
    • Virtual Events
    • Volunteer
  • Donate
    • Support CRWA
    • Campaign for the Charles River
    • Planned Giving
    • Financial Information
    • Shop CRWA