The Cambridge and Somerville city councils have both passed policy orders pushing back against a proposed $1.3 billion regional sewer overhaul, calling for stronger measures to prevent sewage from spilling into local waterways as climate change brings increasingly intense rainstorms.
Like many older cities, Cambridge and Somerville have aging sewer systems that carry wastewater and stormwater through the same pipes. During heavy storms, those pipes can become overwhelmed, forcing a mixture of stormwater and untreated sewage into nearby waterways, including Alewife Brook and the Charles and Mystic rivers.
The proposed Draft Updated Combined Sewer Overflow Long-Term Control Plan, developed over four years by the Cambridge Department of Public Works, Somerville Department of Infrastructure and Asset Management and Massachusetts Water Resources Authority (MWRA) to meet federal Clean Water Act requirements, calls for infrastructure improvements intended to eliminate overflows during a typical year under projected 2050 climate conditions.
The heart of the disagreement lies in the plan’s ambition. Although the improvements are projected to eliminate sewage discharges during an average year in 2050, storms of unusual intensity expected roughly once every five years or 25 years would still overwhelm the system. Critics argue that the region should pursue stronger protections against these more severe storms, even at a greater cost.
On Oct. 22, the Somerville City Council voted 9-1, with one member absent, to oppose the draft plan and call for a more comprehensive regional solution. The resolution, sponsored by Councilors Emily Hardt, Jon Link and Will Mbah, calls for the “virtual elimination” of combined sewer overflows.
“This is a technical plan to address what I see as a political problem,” Hardt said, arguing that the proposed improvements would require years of construction and substantial investment without adequately preparing the region for future storms. “We don’t want to have a halfway solution that just kicks the can down the road to future generations when it’s going to be a bigger problem and a more expensive problem,” she said.
Hardt pointed to the public health consequences of sewage discharges, noting that Alewife Brook flooded nearby recreational areas five times in 2023. Sewage discharges into the brook have continued since then, including multiple incidents recorded by Cambridge and Somerville this year. “Studies have found that when there are significant CSO events, there’s a corresponding increase in emergency room visits for acute GI illnesses,” Hardt said.
Cambridge City Council took a less combative approach Oct. 5, unanimously asking City Manager Yi-An Huang and city staff to advocate for stronger sewage overflow controls and the virtual elimination of CSOs by 2050, without formally opposing the draft plan.
“While the city stands behind this [proposed plan], we, the City Council, really want more,” said Cambridge City Councilor Patty Nolan. “Not to get too simplistic or too graphic, but it is literally true that when these CSOs happen, there’s poop floating around in streets and we really don’t want that,” she added.
Boston’s City Council took a stance somewhere between its two northern neighbors, formally opposing the draft plan in a nonbinding Aug. 26 resolution calling for protections against sewage discharges during storms up to the intensity of a 25-year storm under projected 2050 climate conditions, rather than explicitly demanding the “virtual elimination” sought by Somerville. The resolution urges the agencies developing the plan to adopt stronger protections before it is finalized.
“We should not accept a long-term plan that allows untreated sewage to continue entering our waterways when there are infrastructure solutions available to significantly reduce these discharges,” said Boston City Council President Liz Breadon, who introduced the resolution.
Although Boston was not involved in developing the plan, it shares the Charles River with Cambridge and would be affected by continued sewage overflows.
Not everyone agreed that the region should pursue stronger protections at a potentially greater cost. “The current plan’s projected annual increases of 15 percent or more year after year for every Somerville ratepayer is already a colossal burden,” said Somerville City Councilor Ben Wheeler, the lone vote against the Oct. 22 resolution.
The $1.3 billion proposal already has significant financial implications for residents. According to projections provided to Cambridge Day earlier this month by officials in both cities, the average annual sewer bill for a single-family household in Cambridge could rise from approximately $1,200 in fiscal 2026 to $3,300 over the next 30 years, an increase of roughly 175%. In Somerville, a typical household’s annual sewer bill is projected to rise from approximately $850 to $2,600 by 2055, more than tripling.
Those increases are projected even as the $1.3 billion plan’s cost would be spread across the MWRA’s 43 sewer-service communities.
The public comment period remains open through Oct. 30. Residents can also provide feedback at a final public hearing Wednesday, Oct. 28, at 6 p.m. at Somerville City Hall or remotely via Zoom.
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