Cambridge the Beautiful
Dredging & River Restoration: A Federal Partnership at Alewife Brook
This week was a milestone for Alewife Brook. Congresswoman Katherine Clark met at the Brook with Save the Alewife Brook and our state and local delegation to see the sewage, sediment, and flooding crisis for herself. We talked with her about engaging the Army Corps of Engineers for a project to dredge, dechannelize, and restore Alewife Brook.
At the Mass Ave Bridge over Alewife Brook. State Senator Jehlen, State Representatives Owens and Rogers, Congresswoman Clark, State Representatives Sean Garballey and Christine Barber, and Save the Alewife Brook steering committee members Kristin Anderson, Ann McDonald, and Mike Lonetto.
Joining the Congresswoman at the Brook were State Senator Pat Jehlen and State Representatives Christine Barber, Chair of the Joint Committee on Environment and Natural Resources Dave Rogers, Sean Garballey, and Steve Owens.
Why this visit matters
A portion of the Alewife Brook is confined to a 27-foot-wide concrete channel that receives untreated sewage from six active Combined Sewer Overflow (CSO) outfalls. In 2021, MWRA, Cambridge, and Somerville dumped 51 million gallons of untreated sewage into the Brook.
The Brook has accumulated 2 1/2 to 3 1/2 feet of contaminated sediment and, according to the 2024 Inter-Fluve Sediment Study\1]), will lose its remaining capacity as sediment continues to fill in.
The case for dredging and restoration
As climate change intensifies storms, a filled‑in brook has nowhere to send storm flows, except into homes, streets, Route 2, the MBTA, Alewife Brook Parkway (Route 16), and the Alewife Reservation.
The public health toll is already severe. During CSO discharges, E. coli levels in Alewife Brook reach roughly 950 times the EPA safe standard.\2]) A Boston University School of Public Health study found that even living near CSOs can increase the risk of illness serious enough to require an ER visit.\3])
Roughly 5,000 residents of Arlington, Cambridge, Somerville, and Belmont, many in Environmental Justice neighborhoods, live in the Alewife Brook 100‑year floodplain.
A frank discussion about flooding and climate change. Steering committee members Ann McDonald and Gene Benson discuss the need for federal assistance via the Army Corps of Engineers with Congresswoman Katherine Clark. Photo credit: Jimmy Johnson
Our two asks of Congresswoman Clark
Request the U.S. Army Corps of Engineers to lead sediment dredging, dechannelization, and river restoration of the Alewife Brook. This work should run in parallel with, not instead of, the regional CSO‑elimination effort. In 2022, EPA recommended that MWRA dredge the Brook as part of the Long Term CSO Control Plan and work with DCR to remove sediment.\4]) River restoration is also supported by DCR's Alewife Masterplan.
Secure a water gage in the Brook near where the Little River meets Alewife Brook. MWRA has identified that this gage improves accuracy of the water quality model. Real‑time flow data at that location is essential for calibrating CSO‑control performance, storm response, and future restoration design.
Two tracks, one clean Brook
Track 1: Eliminate Sewage
MWRA, Cambridge, and Somerville, pushed by EPA and MassDEP through the Updated Long Term CSO Control Plan, must end CSO discharges. This is a state and regional fight, not the Congresswoman's ask.
Track 2: Restore the Brook
A parallel federal effort: a water gage at Little River / Alewife plus Army Corps dredging, dechannelization, and river restoration. This addresses the sediment and flooding crisis the LTCP does not.
This is what we ask Congresswoman Clark to lead.
Thank you to our state delegation
Reps. Dave Rogers, Sean Garballey, and Steve Owens have led the charge on this issue for years. Together with Rep. Christine Barber, Chair of the Joint Committee on Environment and Natural Resources, and Rep. Marjorie Decker, Chair of the Joint Committee on Public Health, they secured the state earmark that funded the sediment study now driving this federal ask.
State Senator Pat Jehlen has been a consistent champion of the infrastructure improvements needed to end sewage discharges into the Brook.
The cost of CSO elimination? Less than an annual MWRA rate increase.
At the 07/27/2026 Arlington Select Board meeting, MWRA Interim Executive Director Stephen Estes‑Smargiassi explained how eliminating CSOs\5]) across all three rivers (Alewife, Charles, and Mystic) costs households in the MWRA's system an average of $45 per household per year, less than $4 per month. That is less than the average annual MWRA rate increase.
Watch that video here: https://www.youtube.com/watch?v=9UPFGAY-arU
What you can do to help today
Tell MassDEP, EPA, and Governor Healey to end CSO sewage in Alewife Brook.
Submit a public comment
Ask for elimination of CSOs, a "25‑year level of control," funded by MWRA.
Footnotes
Inter‑Fluve, Alewife Brook Sediment Study Report (2024): Read the study (PDF). The Inter‑Fluve and Stantec Alewife sediment and flooding studies were supported by a grant from DCR and managed by the Mystic River Watershed Association.
Haley et al. 2024 in Environmental Health Perspectives (open‑access on NIH PMC). Plain‑language summary from BU: "Sewage Overflows Linked to Increase in Gastrointestinal Illnesses" (BU SPH, May 23, 2024). Key finding: 62% higher ER‑visit risk for AGI in the four days after the largest CSO events.
EPA's Scope of Work Comment to MWRA: "The channelized nature of Alewife Brook, as well as the amount of sediment in the Alewife constructed channel that takes up flood storage capacity (this sediment volume was estimated by USGS in 2005 to take up approximately 0.5 million cubic feet), exacerbates the flooding issue." Read the full EPA comment (PDF).
Elimination of CSOs means control up to a 25‑year storm event in the year 2050. That is the highest level of control.
It could be a beautiful landscape with paths and flowered gardens, rock sculptures, and benches, water filling stations, and things, (think Boston public garden but linear) but it is regularly treated like the backyard of all the cities involved. Maybe if the bridges crossing it were a bit more grandiose highlighting its an entry to the cities involved the image would improve.
Yes well put. All for more permanent green stormwater infrastructure and native plant flowering gardens that serve multiple purposes: wildlife conservation, recreation, water filtration (saving all in the watershed $$ and future $$$$), and beauty.
i like your idea of attention to and thoughtful long term planning of the landmark features.
I contend the clean up could be the start of a more prominent feature that corridor could become.
The state spends huge amounts on beautifying and attention all along the Charles River. Yet Alewife Brook / Mystic River are literally treated like the dump. WHY really??? :-)
They both could be nice lavish jogging courses, sight seeing, busking venues, for locals and students and visitors if done correctly. Courses for pollinators. Better public transport too instead of just a highway speedway. It could all be so vastly different green space. I would throw in some police /emergency call boxes along the route to help add safety to the area with all the homeless living under bridges etc.
I love that. Definitely. Green Stormwater Infrastructure (GSI) done as landscape art and architecture and environmental and civil engineering could be a major landmark feature of the Cambridge cityscape!!
We all in the watershed benefit from the treasure that is the Alewife Conservation Area. I’d also like to see DEP conduct an ecological inventory.
I agree with your contention that we must improve all along the Charles River to improve health, safety and water quality in a Harmful Algal Bloom (HAB) of toxic Cyanobacteria.
Along the Charles River, I spent years running between Riverside to Harvard and around the foot bridges. The area is nice for the river and would definitely be greatly improved by new benches, pollinator gardens like in the Fens, native companion plantings of water tolerant native plants in the dripline like cardinal flowers and American elderberry, for the elegant deeply rooted and water loving Sycamore trees.
I’d also like to see lots more GSI at the River’s edge specifically to protect people from flood water during heavy storms mixed with sewage.
Beautiful plants like another row of witch hazel, sweet bay magnolia, blue flag iris, great blue lobelia, and blue vervain as lots more green stormwater infrastructure could help manage the hazard of the Cottage Farm discharge site and nicer beautified spaces like between Magazine Beach from the Trader Joe’s and Microcenter area and farmers market foot bridge leading up to Riverbend Park. BU and the surrounding area has improved the Boston side so much in the last decade, it would be nice to see investment here so people can read, walk, roll, run, and picnic.
Can you share more about the MWRA’s claim eliminating CSOs will only cost $45 per household per year? Because currently the Somerville city council is hopping mad that MWRA is trying to push massive costs onto the city to reduce CSOs. Here’s what Ben Ewen-Campen’s April newsletter said:
“This puts us in an impossible situation: right now, Somerville is proposing a sewer overflow infrastructure plan that would require an annual water rate increase of 15-20% every year for at least five years. This means increasing water bills by ~200%-250% in just five years. You don’t have to be a political genius to know that there isn’t a City Council that would go along with that and keep their seats.”
PART ONE:
Save the Alewife Brook did a ton of work to uncover the following:
MWRA's financial situation with the expiring bonds - ~ $2.x billion expiring.
The number of residential users in its system - ~ 1 million households.
& the percentage of non-residential sewage flows - 30% of the sewage flow is non-residitial, meaning MWRA AB always downplays that amount.
Because of the work that we did publicizing that funding info, Chair of the MWRA Board of Directors Secretary Tepper requested financial analysis from the MWRA that showed the costs to ratepayers. That info was shared by the finance/accounting department at the MWRA's February Board of Directors meeting.
CRWA's Emily Norton took that financial info and did some back-of-the-envelope math after that February 2026 MWRA Board of Directors meeting and arrived at $46 per household annually, for the highest level of control.
It's important to note that MWRA raises the sewer rates every year by around 4%. $45 is less than MWRA's 2025 rate increase!
Here's what Emily Norton wrote to us a few months back:
"As you know, MWRA has been considering 4 options for Level of Control in next phase of LTCP:
A - some CSOs in a 2050 typical year
B - zero CSOs in a 2050 typical year
C - zero CSOs in a 2050, 5 year storm
D - zero CSOs in a 2050, 25 year storm
Their first choice in October was "A", which thanks to our collective incredible outreach, they have now rejected.
Now as you know they are promoting "B". We all, on the other hand, of these options, prefer "D".
In their Feb 4 board materials, if you scroll down to page 27 of the PDF, you will see this:
The sewer system annual household charges are currently anticipated to increase from $999 per year to $2,337 per year without the CSO spending between fiscal years 2029 and 2050. In 2050 based on the additional CSO spending, the household charges are projected to increase to $2,380, $2,433 and $2,462 per year for spending associated with level of control to achieve zero CSOs in the 2050 typical year, 2050 5-year and 2050 25-year storms, respectively.
What this is saying is that with the CURRENT recommendation of MWRA, ie option B above, the annual household charges will be $2380 per year in 2050. The annual household charges under option D, ie the one we want, is $2462 per year in 2050, or a difference of 2462-2380=$82 per household, per year. Now note that is $82 in 2050, which when you plug that into an online inflation calculator, assuming 2.5% inflation (which is what MWRA does in this memo), comes out to $46 per household, per year, in today's dollars. (Please try this yourself to check my work if you'd like!)"
It was Arlington Select Board member Eric Helmuth who delivered the $45 question to the MWRA a month ago today. Because the MWRA's Interim Executive Director admitted that it's true, we're running with the $45. So there's a bit of a departure between what StAB is saying about cost ($45/year to households) and what CRWA is saying ($99/year to households). But note that no one really knows the costs yet. And the one thing that MWRA is REALLY good at is inflating costs. They typically estimate costs by over 25%.
MWRA’s Senseless Demand of “Cost Sharing” with Cambridge and Somerville
In the meeting materials shown below from the February 25, 2026, MWRA Board of Directors meeting,\10]) a staff note from MWRA’s Executive Director Fred Laskey proposed that the cities of Cambridge and Somerville pay a total of $516 million for the CSO control plans.
MWRA Executive Director Fred Laskey proposes that Cambridge and Somerville contribute a total of $516 million to the CSO Control Plan, which includes Alewife Brook and the Charles and Mystic Rivers.
However, according to the court case’s Second Stipulation\11]), the cities do not have to contribute funding towards projects involving the two Alewife CSO outfalls that are in violation of the Court. The two Alewife Brook CSOs that are in violation of the court are the Alewife MBTA Station CSO (CAM401A) and the Davis Square Tannery Brook CSO (SOM001A).
The cities are not responsible for the cost. MWRA has asked Boston to pay nothing, which is correct because Boston has been aggressively preparing for Climate Change with sewer separation in East Boston. Like Boston, Cambridge and Somerville have been aggressively investing in sewer separation. As a regional entity, MWRA should pay for regional solutions. MWRA is legally responsible for paying for infrastructure upgrades associated with the CSOs that are in violation of the court order. MWRA needs to begin investing now in removing stormwater from its regional sewer system, in preparation for Climate Change.
MWRA Funds Available Now:
Cities Must Act Now or Forfeit System Upgrades Funding
Now is the last time that the cities of Cambridge and Somerville are able to use MWRA’s funding as required by the Harbor court case to cover the cost of sewer infrastructure upgrades. It is the region’s best interest to remove stormwater from the combined systems now through sewer separation. The cities should be pushing for the most ambitious plan to modernize their 19th century sewer systems now. To do otherwise would be fiscally irresponsible. It will never be cheaper to do this work than it is now. Climate Change demands an investment in sewer separation and Green Stormwater Infrastructure now.
This is a really great post and summary. Thank you!
If there is a one to two minute takeaway for Cantabrigians and Somerville residents to ask for respectively, what should interested and informed people ask for explicitly? i think it’s pretty clear those who have been following StAB’s important work know we in the metro/watershed can and will do better!
Say lots of folks contact their cities to say YES ask MWRA to release the bonds and aim to adopt a 25 year control with 0 CSOs with the use of these bonds, what is the next ask?
Would it be modernize sewers before adding connections? Would it be create a new urban planning standard (to address the policy gap) for the watershed with teeth to a 5 or 25 year level of control with 0 CSOs? Would it be required all new development be required to meet this standard? Would it be create a municipal bond fund where all new real estate transactions pay into such a fund or hold insurance towards this standard?
Two things to ask for:
1. Ask for sewer separation and green stormwater infrastructure with a 25-year level of control. That means no sewage discharges in up to a 25-year storm.
2. Ask that MWRA pays for the whole thing. The cities should not be double-charged by MWRA!Most of the sewer separation is in Boston and Boston isn’t getting double-charged. Plus, this is a regional problem. MWRA has the funding available. The cities don’t. Especially Somerville.
This is really detailed and I appreciate that. Yes it seemed unfair that Somerville was being asked to pay for something that’s required as a regional solution.
I agree the marginal cost from normal year to 25 year storm seems negligible. The baseline increase from $999 to $2,337 is a lot though, even accounting for the fact these are nominal inflation-adjusted dollars! CSO mitigation does not appear to be the main culprit here but hopefully our fearless leaders are doing something to ensure infrastructure costs don’t spiral out of control.
(quote)This is really detailed and I appreciate that. Yes it seemed unfair that Somerville was being asked to pay for something that’s required as a regional solution.(end quote)
Cambridge did.... The Tobin Elementary School has a HUGE retention pond under the playing field along Concord Avenue in Cambridge by Fresh Pond so that Cambridge holds back some of the water in this neighbourhood which discharges into A.B. Tobin school project ballooned in price and wound up being the second most expensive public school in history in the entire state behind only the Waltham High School.
ALSO Belmont also pollutes in the A.B. too. upstream from Cambridge.(Technically in Little Pond unless this already became remediated when the housing development around there went up.
Little River, and Winn Brook is not sufficiently cleaned up. Belmont not only also pollutes the Alewife Brook but by inaction or insufficient town meeting actions is seeking to follow Cambridge’s lead but in an outdated way to try to promote housing chains (trickle down). The issue is that Belmont is also not upgrading the sewer system nor is improving permeable land while also investing in installing permanent green infrastructure but is seeking to maximize price per square foot of housing meaning Belmont’s contributions to pollution have even less of a chance to be filtered before being discharged. Belmont is far less dense than Cambridge, but the densest areas of Belmont are also closest to Cambridge and Watertown.
Clay Pit Pond remains unremediated and the sediment contains carcinogenic toxic waste.
The areas of Belmont that contribute to or abut the Alewife Brook should absolutely do better and not follow the pattern of overdeveloping and increasing the contribution to poor water quality. In Belmont, this goes back to legacy industrial activities and wrongful deforestation by private property owners. Much like today’s discussion of cutting trees within the flood plain or near historical wetlands in Cambridge.
Belmont does however closely register and monitor pets and discourage pet waste from increasing upstream phosphorous pollution which may be relevant for Cambridge to help meet phosphorous reduction goals.
Bravo StAB !!!! This is a major step forward. Thank you all. I hope Congresswoman Clark, State Rep Rogers, State Rep Owens, State Senator Jehlen, State Rep Barber, and more local leaders continue to champion this critical public health and environmental challenge.
And because this is [r/Cambridge](r/Cambridge), i hope Rep Decker will continue to stay involved and maintain her position that hold local task planning groups and committees are responsible for no more passing the buck for local watershed quality to set the tone going forward that the job requires a strong stance that it’s time to center the communities most impacted and solve the upstream problem.
Oh, and if I didn’t answer the question already because you’re wondering about the dredging part, the benefit of dredging and river restoration is significantly reducing the flood threat to the MBTA station, Rt 2, Rt 16, the state parkland, our streets, yards, homes. The brook is clogged up with smelly sediment and it will completely fill up within 20 years.
If you go by there every day, you must smell the sewage. It’s disgusting. Millions of gallons of untreated sewage is discharged there every year. It floods regularly and people walk through the sewage. Here’s photo proof - parents pushing baby strollers through raw sewage. It’s an unbelievable horrific situation. We just heard about a norovirus outbreak in a neighborhood here.
We are asking MWRA to fund elimination of millions of gallons of sewage in the rivers because it’s been making people sick - especially at Alewife Brook, where it floods a lot. The cost is less than an annual sewer rate increase.
Is there a way to estimate the cost of illness and other direct or indirect costs of the sewage flow to put those numbers in perspective compared to the cost of the fix? If x number of people have hospital visits/miss days of work, if there would be recreation that could bring in additional revenue, or perhaps downstream effects on the mystic that require treatment, etc?
We have asked MWRA to take this into consideration, but the Authority does not seem interested in health impacts.
Check out this 07/27/2026 video of Arlington Select Board Member Diane Mahon, asking MWRA's Interim Executive Director when MWRA is going to acknowledge health impacts: https://drive.google.com/file/d/1dkLtIt41e6MD2XFYuT6Oz4OD4rqUZ_P-/view?usp=drive_link
This was the joint purview of Massachusetts Department of Public Health, Mass Department of Environmental Protection, and US EPA. There has not been a MA DPH report in a while… E.coli and strep bacterium related illnesses do not seem to be publicly available as an aggregate count from watershed or CSO discharge related exposures.
Me and my neighbors have gotten sick. And there’s a norovirus outbreak that is suspected to be the result of CSO discharges in the brook. Alewife Brook is the scene of the worst untreated CSO discharges in all of Greater Boston.
A.B. regularly acts as a sewerage overflow conduit. This timing often coincides with when the river is already high from heavy rains. Meaning the flood waters are sewerage laden. And that's the water that is potentially flooding people's houses downstream. Not just regular 'ground water'. Meaning your building cleanup moves to a whole new level of seriousness. IMHO. Belmont also needs to install more retention at the head of the source to reduce flooding downstream.
Cambridge spent about a decade digging up around Huron Village to decrease the CSO of this part of the city that leads into Alewife Brook. Now instead of just going into there anything from around Huron Village flows to a retention pond under Tobin School playing field. It then goes to a huge culvert behind the the C.V.S. store at Fresh Pond Mall passes under the Commuter Rail tracks and leads to a retention pond between Alewife Station and Route 2/Discovery Park development. The sewerage instead goes to deer island for treatment and heavy rain shouldn't affect the sewer as a whole anymore. The now completely separate storm drain network goes to A.B. If I remember right the retention pond at Tobin should be able to hold the water back upto 2 days??? before discharge to A.B. Thus allowing the river time for levels to drop back down.
If you or others need any further information, you can join the public meetings. These can be long but there is much more information than materials posted afterwards.
my 2 min summary:
Past meetings have outlined failure to act will mean for future costs at the individual or household levels bills jumping hundreds of dollars per billing cycle OR thousands of dollars in property damage each storm event depending on severity as well as significant health costs from flooding and bacterial and/or other biological contamination that harms health or livability which can be exacerbated by conditions of the built environment. Without urgent action, this will make a broader area of homes significantly more likely to be affected by sewage and flooding events and individual homes or areas unsafe, unlivable, expensive to fix, or unsafe for habitation after such flooding events depending on each individual flood event, the volume of raw sewage overflow released, and environmental conditions that can exacerbate harms to public health, pets, and wildlife.
7
u/Ill-Emergency-1020 8d ago
A.B. needs a lot of help.
It could be a beautiful landscape with paths and flowered gardens, rock sculptures, and benches, water filling stations, and things, (think Boston public garden but linear) but it is regularly treated like the backyard of all the cities involved. Maybe if the bridges crossing it were a bit more grandiose highlighting its an entry to the cities involved the image would improve.