The Boston Harbor Clean-Up worked wonders in the Boston Harbor and in the Charles River, but Massachusetts Water Resources Authority’s claim that they have achieved an 85% reduction of combined sewer overflows to the Alewife Brook is not consistent with their own data about the vast quantities of sewage actually discharged into our little brook in recent years.
In 2021 the sewer operators’ own websites (MWRA, Cambridge, Somerville) reported that over 50 million gallons of untreated sewage pollution was discharged into the Alewife Brook. That’s the same amount of sewage pollution as was dumped in the Alewife in 1994, before work began to try to fix the problem.
So, why does the MWRA claim the Alewife sewage pollution problem is 85% better? MWRA’s 85% improvement assertion is based on their flawed computer modeling based on the “Typical Year” (a hypothetical “average” year). They have actual metered data that could be used to evaluate their progress, but they assess themselves using fanciful modeled results instead.
The MWRA’s Typical Year model results bear little resemblance to the current reality in the Alewife Brook because it is based on old weather data going back to 1949, with no acknowledgement of the dramatic changes in precipitation brought about by Climate Change. Increases in storm intensity & volume of rains are causing exponential increases in sewage discharges.
MWRA’s own chart below shows the actual volume of sewage pollution dumped in the brook vs. the MWRA modeled sewage volume. When you compare the actual volumes (gray bars) to the modeled volumes (blue bars), it becomes clear that the MWRA’s model is out of touch with reality.
Note that, until their Alewife sewer separation work ended in 2015, actual sewage discharges decreased as a result of Cambridge’s excellent sewer improvements. The MWRA’s modeled data (blue bars) implies that these positive impacts from Alewife sewer improvements persisted, while the sad reality of exponential increase in actual sewage pollution (gray bars) is undeniable. Over the last seven years, there has been 250% more sewage pollution than the MWRA’s computer model admits.
Why are the sewer operators using modeled data? There is a legal reason for the MWRA’s flawed modeling. As part of the Boston Harbor Cleanup court case, the sewer operators are required by law to reduce their sewage pollution discharge amounts by 85%. They use this computer model to show that they aren’t breaking the legal limit. If the model showed the truth over the last seven years, they would be out of compliance with the law!
So, whenever you hear the MWRA use the words “Typical Year” or “Average Year,” remember that they are not talking about the actual amount of sewage pollution. They are talking about flawed computer modeling that the MWRA created to fulfill a legal requirement of the Boston Harbor Cleanup court case.
Climate Change is Here.
The solution to the Alewife sewage pollution problem is – most urgently – treatment of all sewage discharges, continued sewer separation by the cities to allow for eventual elimination of discharges, and upgrades to the MWRA’s Northern Branch sewer system to handle increased flow to their Deer Island Treatment Plant. The MWRA must end the dumping of untreated sewage into our little brook! This will require significant new sewer infrastructure. MWRA will only invest in this infrastructure if we, the public, insist that they do.
The planning and assessment of new sewer infrastructure requires an honest look at the actual data. That is why the new Alewife CSO (Combined Sewer Overflow) Control Plan being drafted now must include forward-looking Climate Change projections. Climate Change is here – there are no more ‘Typical’ or ‘Average’ Years.
Help End Sewage Pollution!
Please come to the virtual sewage planning meeting Wednesday, June 29th at 6 PM. The Alewife Brook belongs to the people. Tell the MWRA that they must end the dumping of untreated sewage pollution in our little brook!