Report Card Grades
WATER QUALITY REPORT CARD
On June 17, 2025, CRWA gathered with Mystic River Watershed Association, Neponset River Watershed Association, state and local leaders, and community partners to announce the 2024 Water Quality Report Card Grades for the three rivers that flow into Boston Harbor––the Neponset, the Charles, and the Mystic.
Since 1995, U.S. EPA has issued the annual Charles River Report Card to report the recreational health of the Charles River. The 2024 Report Card Grades, which range from A to C+, show vast overall improvements compared to prior decades yet illuminate how the weather extremes of drought, heat, and increased precipitation impact river health, safe recreation, and enjoyment of these rivers, at a time when residents rely on them most.
WHAT DO THE GRADES TELL US?
Based on our data collected by community science volunteers, the report card grades show the percentage of time public health hazards like E.Coli bacteria, sewer overflows, and cyanobacteria blooms impede safe recreation in four river sections and two tributaries, the Stop River and Muddy River.
In the Charles River, grades ranged from an A in the Upper Middle Watershed, an A- in the Lower Middle Watershed, a B+ in the Stop River Tributary, Bs in the Upper Watershed and Lower Basin, and a C+ in the Muddy River tributary. These grades are slightly improved from last year and follow typical trends. More urbanized, paved areas consistently see lower grades due to stormwater pollution, while greener, more forested areas of the watershed are swimmable on most days.
DIVE INTO THE GRADES!
CLIMATE CHANGE STALLS PROGRESS
Drought in the Charles River Watershed Six Lowest Depths Recorded in September 2024. Data Source: CRWA Volunteer Monthly Monitoring Program
Greater Boston is already seeing the effects of climate change––impacts of increased precipitation, drought, heat, and stronger storms threaten to stall the progress made toward swimmable urban rivers. In the three highly urbanized watersheds, with over 80% impervious cover in some communities, the scale and consequences of heavier rainfall and extreme weather are stark, resulting in more stormwater pollution, frequent combined sewer overflows (CSOs), and flooding. In 2024, heavy rains caused 24 Combined Sewer Overflow events, releasing 47.8 million gallons of sewage into the Charles River. CSOs directly restricted recreation on the Charles River for twenty days in 2024.
IS IT SAFE TO SWIM IN THE CHARLES?
The short answer is… sometimes. And in wet weather, generally no.
Public health hazards, such as bacterial pollution from stormwater, sewer overflows, and toxic cyanobacteria blooms, continue to make swimming and boating unsafe in many sections of the Charles River.
WHAT ARE WE DOING ABOUT IT?
“These grades make it clear: progress has hit a wall. That’s unacceptable — and the public shouldn’t accept it either. The Clean Water Act set a goal of fishable, swimmable rivers by 1983. The EPA’s Clean Charles Initiative aimed for a swimmable Charles by 2005. Those commitments haven’t been met. Cities and towns need to cut back on polluted stormwater runoff, and Cambridge, Boston, Somerville, and the MWRA must stop releasing sewage into the river. A swimmable Charles River is absolutely within reach — but we need the public’s help to put real pressure on decision-makers to invest in the solutions,” said Emily Norton, Executive Director of the Charles River Watershed Association.
We advocate for a clean, resilient, swimmable Charles River in all aspects of our work––one way is by building nature-based solutions, such as green infrastructure in cities and towns, to keep pollution out of the river and build climate resilience. Other options to eliminate CSOs include separating combined pipes or building underground storage to hold stormwater or combined sewage. However, a swimmable Charles River is only possible if decision-makers and the public support the necessary investments to make it a reality.
This legislative session, we are advocating for the CSO Bill, which would eliminate Combined Sewer Overflows (CSOs) by 2050 and incorporate more nature-based solutions to make our communities more resilient to climate change. Join us in telling legislators that it’s time to ‘Cut the Crap.’ Click this link to sign our petition, or send a message directly to your legislators asking for their support. With your help, we can put an end to combined sewer overflows and take a step towards a swimmable Charles River.
