The Dirty Secret About the Alewife Sewer System:

It was Designed to Pollute

In 2015, the Massachusetts Water Resource Authority reconstructed and enlarged the Combined Sewer Outfall known as MWR003 in the Alewife wetland.1 This CSO was enlarged and functionality was added to it, to provide hydraulic pressure relief for the system downstream. Before the MWRA performed the work on this CSO in 2015, its annual discharge was about 60,000 gallons of untreated and undiluted sewage from Belmont, mixed with untreated sewage and stormwater from Cambridge. MWRA expected the reconstruction of this CSO would result in an increase of untreated sewage discharge of around 1 million gallons annually. But last year, in 2021, this CSO discharged 20 million gallons2 of untreated sewage and wastewater.

MWR003, the MWRA’s Alewife Watershed CSO, reconstructed in 2015.

Why did the MWRA design this CSO to discharge more sewage into the Alewife Brook?

This CSO is part of a larger sewer system that is tied to the Chelsea Creek Headworks, where it is screened before flowing to the Deer Island water treatment plant. The MWRA’s Chelsea Creek Headworks receives sewage flows from the following 17 municipalities: Everett, Somerville, Cambridge, Arlington, Burlington, Lexington, Malden, Melrose, Wakefield, Stoneham, Medford, Reading, Woburn, Wilmington, Winchester, Belmont, and Bedford, as seen in the map below. 

This map of the Chelsea Creek Headwork Service Area was provided by the Massachusetts Water Resource Authority.

When flows from these municipalities are experiencing “high growth” during storm events, the Chelsea Creek Headworks runs out of capacity. There’s no room in the pipes because too much stormwater gets into the system. Upstream from the Chelsea Creek Headworks, the Alewife Brook pump station cannot handle the increase in flow because there’s nowhere for sewage to go. This is why the MWRA reconstructed their Alewife CSO, MWR003, made it bigger, and turned it into a relief valve for the rest of the system. The MWRA quite likes CSOs, the reasoning being that CSOs provide more capacity to their sewer system during storm events.3

The MWRA views CSOs as “additional capacity” to their sewer system. From MWRA 2018 Wastewater Master Plan.

The MWRA’s sewage pollution in the Alewife Brook is a feature, not a bug!

The systemic failures in the MWRA’s sewer system impact Alewife area residents.

The Commonwealth and the MWRA have known about the flooding problems in the area for decades now. They have known of the health problems that area residents have suffered following flood events, when raw sewage enters their homes. It is time for the Commonwealth and the MWRA to show that they care about the health of vulnerable area residents, in Environmental Justice communities. They must not design, build, and maintain their sewer system in a way that creates serious health hazards for residents!

It’s time to redesign the sewer system in the Alewife.

Constructed in 1951 and operational in 1952, the Alewife Pump Station is the oldest in the MWRA’s entire system.4 The MWRA’s Alewife Brook Sewer, still in use, was constructed in 1896 or 1897.5  In 1948, a larger sewer line was added to the Alewife and is known as the Alewife Brook Conduit.6 This infrastructure is all so old.  Isn’t it time to install new, larger pipes and provide greater pumping capacity for the Alewife Basin? 

The Commonwealth provides CSO sewage treatment facilities elsewhere throughout the MWRA’s system. For example, the MWRA has 6 CSO sewage treatment facilities: Prison Point, Cottage Farm, Somerville Marginal, Union Park, Fox Point, & Commercial Point.7

Why hasn’t the Commonwealth considered a CSO sewage treatment facility for the Environmental Justice populations along the Alewife Brook

We are at a point in the CSO regulatory process when the MWRA must create a new Long Term CSO Control Plan. Now is the perfect moment for the Commonwealth to ensure that the MWRA redesigns and builds new sewer infrastructure that protects the health of the vulnerable populations who live near the Alewife Brook.

1. 2018 MWRA Wastewater Master Plan P. 11-19, Figure 13
2. MWRA Chart of Alewife CSO Discharges: Metered Data vs Modeled Data
3. 2018 MWRA Wastewater Master Plan P. 9
4. MDC 1953 Sanitary Condition of Spy Pond, Arlington P. 45
5. MPC 1904 Report on Improvement of the Upper Mystic and Alewife by John R Freeman P. 64
6. 2018 MWRA Wastewater Master Plan P. 9-14, Table 9-2, Table 9-3
7. 2018 MWRA Wastewater Master Plan P. 9, P. 11-13, Figure 20 (See Union Park Detention / Treatment Facility)

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