MWRA Final CSO Meeting Bombshells

Mystic Valley Parkway Over Alewife Brook Bridge

On February 17 2022 the Massachusetts Water Resources Authority (MWRA) hosted a public briefing to discuss their Final combined sewer overflow (CSO) Performance Assessment Report. This was based on their four-year CSO assessment, which looked at their system’s CSO performance from 2018 to 2021. This briefing was a requirement of the Federal Boston Harbor Clean-up court case.

There were 90 people logged in to this virtual meeting and almost all of them were community members who were interested in the Alewife Brook CSOs. The briefing began with PowerPoint presentation, where the MWRA gave an overview of their CSO program work and the results to date.


Somerville’s Alewife CSO is out of compliance.

The MWRA has determined that Somerville’s Alewife CSO is not in regulatory compliance. This means that Somerville has failed even to live up to the terms and requirements of their permit to pollute the Alewife Brook. They are discharging far too much sewage and too frequently!

Based on the MWRA’s modeling results using a “Typical Year” approach, the model shows that Somerville’s CSO (SOM001A) is discharging 4.47 million gallons of sewage water compared to the regulatory goal of 1.67 million gallons. Note that the actual measured discharges for Somerville’s Alewife CSO were 18 million gallons of sewage water in 2021.

Somerville needs to separate their combined sewer system in Davis Square, eliminate that terrible CSO, and add green and grey infrastructure to clean their stormwater and reduce flooding. This work can be done on state DCR land all along the Alewife, including at Dilboy Park.

The MWRA cannot currently meet the area’s sewer needs when we have big rainstorms.

After the MWRA’s PowerPoint presentation, the public was allowed to ask questions and make comments. Arlington Town Meeting Member Patricia Worden said that she used to be a Cambridge resident and that she believes Cambridge can afford to close their Alewife CSOs. Worden also asked whether the sewer system can handle more sewer hookups required by future development. Then Gwen Speeth from North Cambridge asked the MWRA why they don’t take care of their own Alewife Brook CSO, MWR003. Speeth pointed out that the MWRA’s Alewife CSO discharged over 20 million gallons of sewage water in 2021.

In response, a consultant spokesperson for the MWRA, Don Walker from AECOM replied,
“The MWRA system is limited by downstream capacity. Under very large storm events, the capacity of the Alewife Brook Pump Station, which is downstream of [MWR003] is reaching capacity – very large facility, has 90 MGD capacity. That then discharges into sewers that are conveying flow further downstream and going to the Chelsea Creek Headworks, that then reaches capacity. And there are events when the capacity of our Deer Island treatment plant, 1.2 / 1.3 billion gallons per day is reached. So there are limits to what the MWRA can push through the system.”

What Mr. Walker is stating here is that the MWRA’s sewer system through the Alewife is not capable of handling the area’s current needs during some rain storms. This is because stormwater in the combined systems is overloading the MWRA sanitary sewer system.

We note that separating the combined sewer systems will greatly reduce stormwater flow into the MWRA system and thus address the capacity issue.

What does this mean for the future? What is the solution?

Climate Change projections and current data indicates that if the CSOs are not closed, the sewage pollution problem will snowball, and become exponentially worse. Therefore, the combined sewer systems which mix sanitary sewage (what you flush) with street water in West Somerville and North Cambridge must be separated. They must stop sending their street water (AKA stormwater) to the Deer Island sewage treatment facility. This will reduce the overloaded capacity on the system. And the MWRA’s Alewife CSO, which dumped 20 million gallons of sewage water in the Alewife Brook in 2021, must be replaced with a pumping station.

Thank you, Alewife Supporters!

Save the Alewife Brook would like to thank all of the supporters who attended the MWRA’s Final CSO report briefing, including:
Adam Chapdelaine, Amy Schofield, Barbara Moran, Ben Beck, Beth Kudaruskas, Beth Melofchik, Betsy Davis, Carolyn Francisco-Murphy, Carolyn M Fiore, Charlie Jewell, Chris Goodwin, Christian Klein, Clare Nosowitz, Dan Codiga, David Wu, Denise Ellis-Hibbett, Don Seltzer, Douglas Heim, Eugene Benson, Eric Helmuth, Eva Murray, Fang Yu, Gwen Speeth, Jane Carey, Jean Devine, Jianjun Wang, Jill Carr, Jim Barsati, Jimmy Johnson, John Reinhardt, John Salo, John Tortelli, Julia Hopkins, Kane Larin, Karen Graham, Kelly Morton, Lealdon Langley, Leon Cantor, Lucner Charlestra, Maret Smolow, Mary Adelstein, Mary Kay, Michael Fager, Michele Barden, Michele Gillen, Mike Altieri, Minka vanBeuzedom, Nancy Bloom, Pallavi Mande, Pam Heidell, Patricia Worden, Patrick Herron, Peg McAdam, Rachel Roth, Rich Raiche, Sally Carroll, Shavaun Callahan, Stephen Perkins, Steve Cullen, Susan Stamps, Susy King, Todd Borci, Tricia Carney, Wynelle Evens, Yuyou Chen.

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