The Massachusetts Water Resources Authority is rolling out a revamped sewer control plan this winter, but people who live along the Alewife Brook, the Mystic and the Charles are being told not to expect clean water every time the skies open up. In heavy storms, raw sewage will still end up in local waterways. Neighbors who walk and bike the Alewife Greenway and nearby parks say that after big rain events, puddles and flooded yards stink, and some residents say they feel sick. The updated package promises fewer routine discharges, yet it leaves the worst storm overflow scenarios largely unresolved.
MWRA staff released a revised set of recommendations and a roughly $764 million plan on Feb. 4, and the agency’s board signed off on a draft earlier this week that now heads into regulatory review. As reported by Axios, the draft models “zero overflows” in a 2050 "typical year" of precipitation, but it would still allow millions of gallons of sewage to spill during rarer, more intense storms.
What MWRA Is Proposing
The staff recommendation mixes storage tanks, micro-tunnels, selective sewer separation and green infrastructure in what officials describe as a compromise between environmental benefits and what ratepayers can afford. For the Charles River, the plan calls for a storage tank of roughly 10 million gallons at the Cottage Farm and Magazine Beach site, along with phased sewer separation across the Back Bay and parts of Cambridge. Agency staff used a 2050 "typical year" rainfall model to show where routine overflows could be eliminated, and they emphasized that full construction would roll out over decades, according to WBUR.
Alewife Brook: The Hardest Hit
By volume, the Alewife basin is in the worst shape. It saw roughly 19 million gallons of combined-sewer overflow in 2024, and watershed data show totals as high as 26 million gallons in earlier years. Local residents and advocates have drawn up their own, more aggressive plan that leans on sewer separation and green infrastructure for North Cambridge and parts of Somerville, with a price tag of about $405 million. MWRA's draft steers roughly $340 million toward Alewife improvements but warns that full separation for the brook could cost about $1.7 billion. Those very different numbers lay bare the tradeoff between substantial short term reductions and a permanent fix, as Axios and the Mystic River Watershed Association note.
Price Tag and Your Sewer Bill
MWRA staff say the recommended package would cost roughly $1.28 billion, which is more than earlier options, and officials warn that household sewer charges are likely to climb sharply by mid century. Staff estimates suggest the average household sewer bill could rise from about $999 in 2029 to roughly $2,300 to $2,400 in 2050 under the plan's scenarios. Tougher controls designed to cut back on overflows during rare, extreme storms would drive rates even higher, WBUR reported.
Activists Say It's Not Enough
Environmental groups argue that the authority's focus on a "typical year" underestimates climate risk and public health impacts. "They voted to invest millions of ratepayer dollars in an outdated system that will continue to dump untreated sewage into our beloved Charles River," Charles River Watershed Association Executive Director Emily Norton said in a press release from the group, calling the draft a missed opportunity. Local advocates say climate driven wet years make a 2050 "typical year" an unreliable basis for planning, according to the CRWA statement.
Health, Recreation and Alerts
Public health officials urge people and pets to stay out of local waterways for at least 48 hours after a combined sewer overflow. In Cambridge, the city posts temporary warnings when discharges occur. The city directs residents to local and MWRA online alert pages and offers signups for real time CSO notifications so people can avoid contaminated stretches of the Charles and the Alewife Greenway, according to the Cambridge Department of Public Works.
What's Next
With the draft plan now in the regulatory phase, the MWRA calendar lists upcoming board and committee meetings that will handle final action and public input over the coming months. If regulators give the green light and construction moves forward, upgrades will unfold over decades, and communities will face ongoing choices about how much they are willing to pay for different levels of protection. The MWRA website posts upcoming meetings and background materials for residents who want to track the process and weigh in.
