The EPA’s 2025 Three Rivers Report Card for the Charles River, Mystic River and Neponset River reflects ongoing struggles with pollution and increased rainfall throughout the watersheds. The grades were “slightly worse than the previous year, with most grades in the B and C ranges,” reports Katie Castellani for the State House News Service:
“In the Charles River, which is about 80 miles long and flows through 23 municipalities, progress has been stagnant or declined in the Upper and Upper Middle watersheds and urban areas have seen slow improvements. The watershed groups say drought, heat, higher amounts of precipitation, cyanobacteria blooms, more frequent stormwater pollution and combined sewer overflows are limiting recreation in the area.
In summer 2025, the river’s Lower Basin saw a cyanobacteria bloom that lasted more than 80 days. Severe drought in 2024 and 2025 led to very low water levels – under six inches in Bellingham, Medway and Newton. In the past three years, there was also about 130 inches of precipitation and 70 known combined sewer outflows that discharged more than 136 million gallons of raw or untreated sewage into the river.
“’These grades make it clear that progress has stalled,‘ said Emily Norton, Executive Director of Charles River Watershed Association. ‘To achieve a truly clean, healthy, and swimmable Charles, we need to make the necessary investments in reducing stormwater runoff and ending sewage discharges.’”
The Muddy River’s grades dropped from C+ to a C in the new report. “The decrease in grade in the Lower Basin can be attributed mainly to the 2025 cyanobacteria bloom, while the decrease in the Muddy River is likely due to a combination of stormwater runoff and the known presence of illicit connections discharging into the tributary. ”
Read the report.
