Alewife Brook Water Quality

I am interning in Will’s office this summer and recently attended a hearing on sewer flows into Alewife Brook and the Charles and Mystic basins, which provided a helpful status update on projects to improve water quality.   The hearing was to extend the variance allowing for a certain level of Combined Sewer Overflows (CSO) into Alewife Brook and the Charles and Mystic watersheds for another three years.  This is a necessary step that is basically acknowledging that the work to reduce CSOs has not been fully completed yet.

Much progress has been made, however, and the full plan to reduce CSOs is court-ordered to be completed by 2020.  All of the Alewife Brook projects, however, are scheduled to be completed by 2015.  Once the plan is fully implemented it will have reduced annual CSO volume into Alewife Brook by 85%, from 63 CSO discharges totaling 50 million gallons per year, to 7 CSO discharges totaling 7.3 million gallons.  Alewife Brook will comply with Class B water quality standards (go to Page 9 in link) 98.5% of the time.  Class B standards mean that the water is swimmable and aquatic life is able to live and reproduce in it.

In the whole Upper Mystic Basin, Lower Charles Basin, and Alewife Brook, CSO volume has already been reduced by 81% from its 1988 level with 73% now treated being treated before flowing into the water.  The watershed-wide goal for 2015 is 88% reduction from 1988 levels with 93% treated.

So far 24 of the 35 projects in the Watershed-wide CSO Control Plan have been completed, and two of the five remaining Alewife Brook projects are currently under construction.  All five are scheduled to be complete by 2015.  The final cost of the projects for Alewife Brook and the Upper Mystic River are estimated at $117 million, a cost shared by the Massachusetts Water Resources Authority and the City of Cambridge.

The plan achieves higher water quality in the brook and rivers by building a storm water drainage system that is separate from the sewer system.  This prevents storm water that has drained into the sewer from causing the combination of storm water and sewage to reach a level where it triggers an overflow into Alewife Brook or the river watersheds.

The extension of the variance was seen as necessary step until the completion of the CSO reduction plan, and was supported by all those who testified at the hearing, including the Charles and Mystic Watershed Associations.  One of the main concerns expressed in testimony, however, was that the frequency and severity of floods is increasing, due to climate change and to conditions on the ground such as more paved surfaces that don’t soak up rainwater as well as dirt or grass.  Another main concern was that MWRA was not releasing sufficient data and information to the public.