Although New England’s most prominent river, the Charles River, flows right through Wellesley, it can be easy for residents to forget all about the 3.9-mile section that winds from the South Natick line to Wellesley Hills. In all, the Charles glides 80 miles from its starting point in Hopkinton, Mass. to its eventual merger with Boston Harbor. It’s the longest river in Massachusetts, and northeast through 23 cities and towns.
It does so on a stealth path through Wellesley. No main driving thoroughfares in town move along the river’s path. And the Charles can be so narrow in certain sections that it might be mistaken for a stream.
Getting to know the river is well worth it, however. You just have to know a few access points to open up this wonderful resource and connection to the natural world.
Organizations such as the Charles River Watershed Association keep tabs on the health of the river, and educate the public about the challenges the Charles River faces.
EVENT: Annual Charles River Earth Day Cleanup
DATE: Saturday, April 25, 2026
LOCATIONS: Wellesley, Natick, and 13 other towns (Dedham, Dover, Franklin, Holliston, Jamaica Plain, Medfield, Milford, Millis, Needham, Newton, Norfolk, West Roxbury, and Weston)
SIGN UP here
The Charles River Watershed Association, in partnership with the Emerald Necklace Conservancy, Charles River Conservancy, Waltham Land Trust, and Esplanade Association, will collect trash from the Charles River and surrounding area with thousands of incredible volunteers. The cleanup brings together over 3,000 volunteers each year to pick up litter, remove invasive species, and assist with park maintenance along all 80 miles of the Charles River.
Progress toward a swimmable Charles River—options to eliminate sewage overflows
From the Charles River Watershed Association:
Jan. 23, 2024–The Massachusetts Water Resources Authority (MWRA) and the cities of Cambridge and Somerville introduced several alternative project concepts to eliminate Combined Sewer Overflows (CSOs) from polluting the Charles River, a significant step toward delivering the swimmable river promised by the 1972 Clean Water Act.
MWRA, Cambridge, and Somerville are required to carry out an extensive updated CSO planning effort to address the ongoing challenge of raw and partially treated sewage being dumped into the Charles River during heavy rain.
CSOs are a key source of contamination to the Charles and are becoming more frequent as our climate changes. In these outdated systems, stormwater and household/industrial wastewater are collected in the same pipes to be conveyed to a wastewater treatment plant, but during heavy rainstorms, the combined system cannot handle the excess polluted water and releases it into the river.
One option MWRA, Cambridge, and Somerville presented was a CSO storage tunnel, a well-established technique to eliminate combined sewage discharges that has been used in Portland (OR), Milwaukee, and South Boston. This innovative tunnel would be designed with climate change in mind, making CSOs a thing of the past in all but the most severe storms expected under future climate conditions.
Additional options presented include implementing green stormwater infrastructure (GSI) in combination with tunnel storage to reduce or eliminate CSOs in smaller storms. GSI provides numerous co-benefits, such as reducing flooding and urban heat impacts, improving air and water quality, and beautifying neighborhoods.
While the MWRA has reduced sewage discharges by over 95% since 1988, tens of millions of gallons of sewage-laden stormwater are still entering the river every year, and that volume is growing thanks to climate change. In 2023, 72 million gallons polluted the Charles, equivalent to 109 Olympic-sized swimming pools.
Charles River Watershed Association —help reduce pollution in the Charles River
Jan. 17, 2025–The Environmental Protection Agency (EPA) recently released a draft permit that could dramatically reduce stormwater pollution in the Charles River coming from large properties with expansive paved surfaces.
The draft permit would require private properties with an acre or more of “impervious surfaces” to implement measures to reduce stormwater runoff such as creating rain gardens or underground infiltration systems.
This draft permit is critical to improving water quality and minimizing the biggest source of pollution in the Charles. Supportive comments are needed before January 29, 2025 to get this draft permit across the finish line.
