Toxic Runoff Contaminating Mystic and Neponset Rivers

CLF petitions EPA to clean up waters and prevent algae outbreaks

The Mystic River. Photo: Shuttersv via Shutterstock

August 24, 2020 (BOSTON, MA) – Conservation Law Foundation (CLF) has filed two petitions with the Environmental Protection Agency (EPA) today to protect the Neponset and Mystic Rivers from stormwater pollution. The petitions request that EPA use its authority to require large properties contaminating the rivers with polluted runoff to obtain Clean Water Act permits.

“Properties have been given free rein to dump toxic pollutants into the Mystic and Neponset Rivers for too long,” said Heather Govern, Director of CLF’s Clean Air and Water program. “Communities surrounding the Mystic and Neponset already see far more than their share of pollution, and toxic algae outbreaks only add insult to injury. It’s time EPA hold these polluters accountable and ensure residents have access to clean and healthy rivers.”

Cyanobacteria, more commonly known as blue-green algae because of its color, is caused by too much phosphorus in the rivers. Exposure to cyanobacteria blooms have been linked to neurodegenerative diseases like ALS, and they are also harmful to pets and wildlife.

During rain or snowmelt, water runoff from urban streets, parking lots, and construction sites carry oil, grease, sediment, phosphorus, and other pollutants into the Mystic and Neponset Rivers. CLF’s petition calls on the EPA to require Clean Water Act permits for large properties like big box stores, strip malls, and major apartment complexes surrounding the rivers in order to limit the amount of pollution.

You can find the petitions here.


As a result of a previous petition filed by CLF, similar properties along the Charles River may now be required to obtain permits to prevent the same type of toxic algae outbreaks. More details about that petition are here.

CLF experts are available for further comment.

###