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Charles River

The Charles River Initiative

The Charles River Initiative

Chart: Reduction of Combined Sewer Overflow Discharges to Charles River (1988-2013)View a larger version of image.
The controls MWRA implemented resulted in a dramatic reduction of CSO discharges to the lower Charles River. Reductions went from over 1.7 billion gallons per year prior to 1988, down to approximately 20 million gallons (MG) in 2014. Discharges are projected to drop to 6.88 MG in the next few years, and over 90% of those discharges will be treated at the Cottage Farm facility. This represents an approximately 99% decrease in CSO discharges to the Lower Charles River since 1988.

In 1995, EPA launched an ambitious effort make the Charles River both fishable and swimmable. Thanks to partners in numerous federal, state and local agencies as well as nonprofit groups, private institutions and citizens, the Clean Charles River Initiative has improved water quality in the river.

Using sound science, cutting-edge technologies and strong targeted enforcement, EPA and its partners have determined the causes of pollution and poor water quality in the River.

Since 1995, municipalities and the Massachusetts Water Resources Authority (MWRA) have made remarkable strides to improve water quality by reducing illicit sewage discharges to storm drain systems and Combined Sewer Overflows (CSOs), respectively.

The municipalities of the lower Charles River (including: Boston, Cambridge , Newton, Brookline Watertown and Waltham) have reduced sewage-contaminated stormwater flows through illicit storm drain connections. That effort has eliminated in excess of 48,000 gallons of sewage contaminated stormwater flowing into the River per day since 2004. This is in addition to the more than one million gallons per day of sewage contaminated stormater that has been eliminated from municipal storm drain systems from Watertown to Boston harbor, an effort that began with the launch of the Charles cleanup effort in 1995.

Sewage discharges from CSOs to the river declined significantly as a result of the 2005 settlement between EPA and the MWRA. As a result of various CSO projects throughout the lower Charles (in many cases, eliminating CSOs entirely, MWRA has reduced CSO discharges by an impressive 99.5%).

We have made significant progress targeting bacterial sources of pollution in The River. But, there continue to be problems with excessive amounts of nutrients entering the river, especially phosphorus. See the Environmental Challenges for updated overview of these latest challenges.

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Sound Science on the Charles River

The improvements in water quality on the Charles River are a direct result of sound science. EPA, U.S. Department of Interior Exit, U.S. Geological Survey Exit, Mass DEP Exit, Charles River Watershed Association Exit, Rocky Mountain Institute Exitand New England Interstate Water Pollution Control Commission Exithave conducted studies and produced reports analyzing the River.

Please see Reports and Links for a more complete view of reports on the Charles River.


Today we have a river that is safe for recreational boating virtually all of the time, and safe for swimming 70% of the time. It is a river that is now a resource for an active wind surfing community, an annual swim race and catch and release fishing. Indeed, we are much closer to the original goals of making the Charles both fishable and swimmable.

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Swimmers on the Charles River
Swimmers on the Charles River

Annual Report Cards

EPA uses the Charles River Report Card to measure and evaluate progress towards meeting the State of Massachusetts bacterial water quality standards for swimming and boating.

Agency scientists evaluate water quality data collected by the Charles River Watershed Association at ten locations in the lower Charles River. EPA then determines how often these samples meet Massachusetts water quality standards for swimming and boating to evaluate our progress towards the overall project goals.

Charles River Report Cards
Based on State Bacterial Standards
Year Overall Grade % Meets Standards % Meets Standards in Dry Weather Conditions % Meets Standards in Wet Weather Conditions
  Boating Swimming Boating Swimming Boating Swimming
2015 B+ 95 69 98 86 93 60
2014 B+ 91 65 100 86 86 53
2013 A- 96 70 97 84 95 63
2012 B+ 87 67 99 93 81 53
2011 B 82 54 96 89 74 35
2010 B+ 86 66 94 86 82 54
2009 B+ 93 62 92 69 94 58
2008 B+ 95 48 91 58 92 42
2007 B++ 100 63 100 84 100 50
2006 B+ 90 62 100 80 84 51
2005 B+ 97 50 97 59 96 32
2004 B+ 96 54 94 68 97 62
2003 B- 85 46 91 56 81 41
2002 B 91 39 100 71 86 21
2001 B 82 54 97 80 74 40
2000 B 92 59 94 82 91 46
1999 B- 90 65 100 71 85 62
1998 C+ 83 51 98 85 74 31
1997 C 70 34 87 56 61 22
1996 C- 57 21 94 40 45 15
1995 D 39 19        
The grade is based on a comparison with previous years and general trends. Given that the grades are based on a limited set of data, some annual fluctuations depending on weather are expected. Figures represent the percentage of time that state bacterial standards are met.

Press Releases

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