We’re Speaking Truth to Power!

On March 11th, 2022, the Charles River Watershed Association, the Mystic River Watershed Association, and Save the Alewife Brook came together to speak with one voice to the Federal Environmental Protection Agency and the Massachusetts Department of Environmental Protection. Together, we collaborated on the following letter about the decades-long Combined Sewer Overflows (CSOs) work; we commented on the history of that work and, more importantly, on the future of the CSO work.

Note that Save the Alewife Brook is a fiercely independent, growing, grassroots, environmental activist organization with supporters in Cambridge, Somerville, Arlington, Belmont, and Medford. Please sign our petition here: Email Petition to End Alewife Brook Sewage Pollution

March 11, 2022

Regional Administrator David Cash
Environmental Protection Agency, Region 1
5 Post Office Square, Suite 100
Boston, MA 02109

Commissioner Martin Suuberg
Massachusetts Department of Environmental Protection
One Winter Street
Boston, MA 02108

Dear Regional Administrator Cash and Commissioner Suuberg:

We are at an important moment in the decades-long fight to eliminate combined sewer overflows (CSOs) in the Charles and Mystic Rivers, Alewife Brook, and Boston Harbor. The original Long Term Control Plan (LTCP) is coming to a close and the Massachusetts Water Resources Authority (MWRA), Cambridge, and Somerville are beginning to plan for future CSO control efforts. On behalf of Charles River Watershed Association (CRWA), Mystic River Watershed Association (MyRWA), and Save the Alewife Brook (StAB), we are reaching out to you and your respective agencies to highlight several important issues and opportunities as we move into the next phase of CSO control planning. We would welcome an opportunity to meet with you to discuss these topics in more detail. Briefly summarized:

  • Despite decades of investment in CSO-reduction projects, MWRA’s CSO discharges are still violating the limits set in the LTCP at more than a dozen outfalls, prompting MWRA to seek a three-year extension (until 2024) to achieve compliance with the court-mandated LTCP. The current LTCP must be fully implemented as close to schedule as possible such that all CSO locations meet or do better than the agreed-upon limits—anything less is unacceptable. MWRA must employ all possible tools at their disposal, including green infrastructure measures, to achieve compliance with the LTCP. 
  • Because the LTCP does not consider increased precipitation caused by climate change or environmental justice, even if MWRA were in compliance with the existing LTCP—which it is not—it would not be a sustainable solution to CSOs. The effects of climate change and environmental justice considerations must be incorporated into future requirements.
  • As MWRA, Cambridge, and Somerville begin the next phase of CSO control planning required by the Water Quality Standards variances, it is critical to incorporate robust public participation early and often in that process, including as the scopes of the plans are developed.
  • We expect the next phase of CSO planning to focus on eliminating CSO discharges into the Charles and Mystic Rivers and Alewife Brook—anything short of complete elimination prolongs the public health risks and environmental harm caused by CSOs.

CRWA and MyRWA both have long, successful histories of partnering with MWRA, EPA, and DEP to improve water quality and habitat conditions in our respective rivers, a task that is becoming increasingly urgent as our climate changes. The emergence of Save the Alewife Brook in the past year, as well as the increased focus on CSOs by residents and community groups throughout the Boston area, is clear evidence that many members of the public share these concerns and are similarly invested in the development of concrete plans to effectively eliminate the remaining CSOs as expeditiously as possible. 

The Water Quality Standards variances for CSO discharges in the Lower Charles River/Charles Basin and Alewife Brook/Upper Mystic River require that MWRA and the cities of Cambridge and Somerville begin the next phase of CSO control planning. The first step is the submission of scopes and schedules for updated CSO control planning, which are due by April 1, 2022. 

Concerns with the end of the LTCP/Post Construction Assessment phase

Much of the work required under the 1997 LTCP, as revised in 2006, has been completed and the success and failure of those measures has now been assessed. Substantial investment by MWRA and the cities of Boston, Cambridge, and Somerville has led to significant progress in reducing CSO activations and volumes. However, sixteen CSOs are violating LTCP limits under “Typical Year” conditions. An additional six CSOs are also violating their respective activation or volume limits, but MWRA states that the difference between actual performance and LTCP limits at those sites should be considered “immaterial.” Further, actual discharges in 2021, as compared to MWRA’s model, significantly violated the LTCP limits for many CSOs. There is clearly much work yet to be done under the existing LTCP, even before increased precipitation and environmental justice are taken into account. 

It is disheartening, if not unexpected, to get to the end of the Post Construction Assessment phase with 22 outfalls still not meeting the LTCP goals. In requesting a three-year extension (until the end of 2024) to comply with its obligations under the LTCP, MWRA informed federal district court judge Richard G. Stearns that they believe they have solutions that can be implemented by the end of 2024 at six of the non-compliant outfalls (BOS003, BOS009, BOS014, CHE008, MWR205, and SOM007A/MWR205A). Of the remaining outfalls, MWRA, coordinating with the Boston Water and Sewer Commission, reports having conceptual ideas at four outfalls (BOS017, BOS062, BOS095 and BOS070/DBC) that they believe will bring the outfalls into compliance with the LTCP if they can be successfully implemented. There are six outfalls for which MWRA, Cambridge, or Somerville do not currently have a solution (CAM005, MWR201 [Cottage Farm], MWR018, MWR019, MWR020 and SOM001A) for achieving compliance with the LTCP. These six outfalls are all within the variance waters. Finally, there are six outfalls that are close to achieving compliance—they have not actually achieved compliance—for which MWRA deems exceedances to be “immaterial.”

CRWA and MyRWA have communicated to the court our position that MWRA must achieve full compliance with the LTCP by the extended deadline of 2024 and that as part of its compliance obligation, MWRA must conduct a thorough analysis of the role green infrastructure and real-time monitoring can play in achieving LTCP requirements and maintaining those requirements as our climate changes.

“Typical Year” vs. Reality

The current LTCP modeling and limits were based on the use of a typical precipitation year, consistent with EPA and DEP LTCP guidance. While that has been standard practice in the past, the reality is that our climate is changing and actual discharges are more frequently and regularly exceeding modeled control limits, and this trend will continue. The difference between actual activations and discharges in 2021 and LTCP limits requires a more detailed examination. 

For example, the cumulative LTCP limits for the six remaining outfalls in the Alewife Brook were 29 activations and 7.29 million gallons discharged. Five of the six outfalls were predicted to meet the LTCP limits under typical year conditions. However, under actual 2021 conditions, there were 45 activations and 50 million gallons discharged. Only two outfalls in the Alewife actually met the LTCP activation limits in 2021. And while 2021 did bring a significant amount of rainfall, LTCP limits were also exceeded in 2018 and 2019. In fact, looking at actual conditions in the past four years, it was only in the drought year of 2020 that LTCP limits were met. Clearly the typical year model no longer reflects actual conditions.

Similarly, in the Charles River, in 2019, based on MWRA’s metering, the following sites had more overflow occurrence than what is allowed under the LTCP: CAM017, MWR018, MWR201 Cottage Farm, MWR023, CAM005, and CAM007. CAM007 and MWR023, both of which MWRA considers to be achieving the LTCP, had 1 and at least 3 more overflows than their respective LTCP limits. These differences were far more extreme in 2021; every CSO location on the Charles River, other than MWR010, exceeded LTCP limits. CAM005 had 9 reported overflows with a volume of 3.2 MG, compared to LTCP limits of 3 overflows and 0.84 MG. At Cottage Farm, there were 5 overflows with a total volume of 88 MG compared to LTCP limits of 2 overflows and 6.3 MG. Even locations that MWRA considers to be in compliance with the LTCP violated the limits: CAM007 had 4 activations and 1.4 MG of overflow compared to the limit of 1 overflow and a volume of 0.03 MG, while CAM017 have 5 overflows with a volume of 13.6 MG compared to limits of 1 overflow and 0.45 MG.            

Given the significant differences between typical year expectations and actual conditions, we expect the EPA and DEP to ensure that MWRA’s next annual report, due in April of this year, provides the agencies and the interested public with the type of analysis of actual precipitation compared to the typical year that was included in the prior semi-annual progress reports. The agencies should also ensure that MWRA provides meter data scattergraphs and results of simulations of the most current hydraulic system model (Q4 2021) under actual 2021 precipitation conditions.

Accounting for the Impacts of Climate Change

The 2021 experience must also inform the CSO control planning process going forward. Whereas EPA’s 1999 CSO Guidance for Monitoring and Modeling is premised on a review of the historical precipitation record, the climate in Massachusetts, and specifically precipitation patterns, has changed significantly in the intervening years and is forecast to continue to do so. What may have been viewed as a static climate system in guidance from the 1990s is now clearly a dynamic one. 

At a minimum, we expect EPA and DEP to require updated calculations for the typical year that account for current and projected climate impacts. It is no longer adequate to rely solely on a historical analysis of precipitation in planning for the future. We also question whether the typical year approach adequately captures the true impacts of climate change.  In looking at the rainfall and CSO discharge data for the previous seven years, we observed that the magnitudes of the discharges in years in which rainfall was above average greatly exceeded the typical year value.

In January, NOAA released a paper titled “Analysis of Nonstationary Climate on NOAA Atlas 14 Estimates” (National Weather Service, Office of Water Prediction, Jan. 31, 2022), which stated that historical assumptions about the magnitude and frequency of extreme future events are not appropriate in the presence of nonstationary climate. Considering that many climate models indicate that the increasing trend in intensity and frequency of precipitation will likely continue in the future, using only statistics from the past observations could underestimate the precipitation frequency quantiles as well as their confidence limits, which could result in undersized civil engineering water resource infrastructure. (p. 6) 

Results of some of the modeling in the NOAA report indicate that overall, the Northeast regional average 2-year 1-day estimates show an increase of between 5% and 22% by the end of the century, while the 100-year 1-day estimates show an increase of between 7% and 30%. (p. 22) EPA and DEP must provide updated guidance to MWRA, Cambridge, and Somerville on considering likely future climate scenarios in their CSO planning simulations.

Environmental Justice Considerations

Since the 1990s—when EPA and DEP last released guidance on CSO control planning—consideration of Environmental Justice has emerged as one of the most important aspects of decision-making on a wide range of environmental issues. Going forward, CSO control planning must take Environmental Justice into account. 

Most of the neighborhoods abutting the Alewife Brook, and the Lower Charles and Mystic Rivers are Environmental Justice neighborhoods according to the Massachusetts 2020 Environmental Justice Population maps published by the Massachusetts Executive Office of Energy and Environmental Affairs. In significant storms, the Alewife Brook has historically flooded Environmental Justice neighborhoods in Arlington, resulting in flood waters containing CSO discharges entering the homes of residents. The areas of Boston and Cambridge immediately downstream of the Cottage Farm discharge are also Environmental Justice neighborhoods and this section of the Charles—which is readily accessible by public transit—is used by many residents, including children, accessing the river through the multiple free or low-cost boating programs such as Community Boating. Environmental Justice is an important consideration in people’s ability to safely recreate in and along our rivers downstream of CSO discharges and must be factored into future CSO control planning.

Expectations Regarding Public Engagement

With respect to updated CSO control planning, we appreciate that the variances require a public participation plan, including ample opportunities for the public to be informed of plan development at critical junctures and opportunities for the public to provide informed comments on the CSO abatement alternatives and recommendations. At the outset, we request that EPA and DEP provide a similar opportunity for the public to offer comments on the proposed scopes and schedules that will chart the course for updated CSO control planning. This will help instill the public confidence and buy-in to the process that is necessary to ensure robust public participation moving forward. To that end, we would welcome a public workshop facilitated by EPA and DEP where MWRA, Cambridge, and Somerville describe their proposed scopes and schedules and answer questions and receive feedback from interested parties. A robust public process is also critical to the Environmental Justice considerations described above.

We appreciate your consideration of these comments, recommendations, and requests, and look forward to working with you towards finally eliminating CSOs in the Charles and Mystic Rivers and Alewife Brook. As noted, we would welcome the opportunity to meet with you in the near future to discuss these issues in greater detail. 


Emily Norton, Executive Director
Charles River Watershed Association

Patrick Herron, Executive Director
Mystic River Watershed Association

Kristin Anderson
David White
Save the Alewife Brook

cc: Frederick Laskey, Executive Director, MWRA
Secretary Kathleen Theoharides, Executive Office of Energy and Environmental Affairs
Mayor Sumbul Siddiqui, City of Cambridge
Mayor Katjana Ballantyne, City of Somerville
Mayor Michelle Wu, City of Boston

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