The following press release is from Mystic River Watershed Association
Arlington, MA, February 25, 2026 — At their monthly meeting this afternoon, the Massachusetts Water Resources Authority (MWRA) Board of Directors voted to approve a plan that would ensure the ongoing release of combined sewer overflows (CSOs) to the Mystic River, Charles River, and Alewife Brook for a generation or more. Though the new plans are an incremental improvement over an October 2025 proposal, which was shelved after public backlash, they still fall short of what our rivers and public health deserve.
“The Mystic River and Alewife Brook, just like the Charles, are treasured resources for hundreds of thousands of people across greater Boston,” says Patrick Herron, Executive Director for the Mystic River Watershed Association (MyRWA). “But MWRA is still proposing projects that have us running in place against climate change as opposed to outlining the investments necessary to create a modernized, 21st-century water infrastructure to match our world-class cities. MWRA’s own financial models show that more ambitious plans are affordable, so why are we holding back on solving this problem once and for all?”
The new proposal promises “Zero CSOs in a 2050 typical year” in the Mystic, Charles, and Alewife, but this description gives a rosier picture than the reality bears out. We know that MWRA’s draft plan would ensure the release of CSOs to all three waterbodies, including the Alewife Brook, in some, if not most, years. We also know that 2050 conditions will not last forever. Climate change is bringing bigger, more intense storms that will cause more CSO activations as time goes on.
MWRA, Cambridge, and Somerville have presented alternatives that go further, and these plans are not budget-breaking. In the data they presented, even the most expensive plans would amount to only about a 10% increase above average base MWRA rates – the cost of an extra lunch out every month. And this rate change would be rolled out slowly, over decades. MWRA’s own Financial Capability Analysis found the projects to have “low impact” for even the most ambitious plans.
With approval from the MWRA board, plans will move next to the Massachusetts Department of Environmental Protection (Mass DEP) and to the US Environmental Protection Agency (EPA), which hold the regulatory authority to approve or amend it. As this process moves forward, MyRWA will continue to advocate for the virtual elimination of CSOs.
Mystic River Watershed at a Glance
The 76-square-mile Mystic River Watershed stretches from Reading through the northern shoreline of Boston Harbor to Revere. An Anglicized version of the Pequot word missi-tuk (“large river with wind-and tide-driven waves”), it is now one of New England’s most densely populated, urbanized watersheds.
Its 21 municipalities are home to 600,000 residents, including many who are disproportionately vulnerable to extreme weather: environmental justice communities, new Americans, residents of color, elders, low-income residents and employees, people living with disabilities, and English-language learners.
The Mystic River Watershed Association (MyRWA) builds shared solutions so that all people, no matter who you are or where you live across the Mystic River Watershed, have safe and easy access to nature and a healthy environment. MyRWA believes that understanding the roots of current inequity, access to information, and opportunities to learn about the natural world empower us all to work together for a better future in the Mystic.