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Charles River water quality earns a "B" for bacterial sampling conducted in 2018

Contact Information: 
Emily Bender (
(617) 918-1037

BOSTON – The U.S. Environmental Protection Agency (EPA) has given the Charles River a grade of "B" for bacterial water quality in the river during 2018.

"The Charles River has been in the 'B' or better range for bacterial sampling for the last 18 years," said Acting Regional Administrator Deb Szaro. "The Charles has seen big improvements in water quality thanks to a strong local partnership working hard to clean up the river, but there is more work to be done to see even more improvements in the future, and we are committed to that effort."

The EPA grade for water quality in the lower Charles River is based on bacterial sampling conducted by the Charles River Watershed Association (CRWA) over the 2018 calendar year. CRWA collects monthly water quality samples at 10 monitoring sites from the Watertown Dam to Boston Harbor. In 2018 during dry weather, 94% of the Charles River samples met the state's bacterial water quality standards for boating, and 66% of the samples met the state's criteria for swimming. In wet weather, the percentage dropped slightly for boating to 91% and dropped more significantly for swimming to 47%, and it is primarily the low wet-weather swimming percentage that drove the grade down this year.

While the grade dipped this year, EPA has still seen significant improvement in the river's overall water quality since the first report card in 1995, when the river was scored at a "D." It met boating standards 39% of the time and swimming standards 19% of the time.

The Charles River grade is determined by comparing the amount of time the river meets water quality standards to the following criteria:

A – almost always met standards for boating and swimming
B – met standards for almost all boating and some swimming
C – met standards for some boating and some swimming
D – met standards for some boating but no swimming
F – did not meet standards for boating or swimming

The lower Charles River has improved dramatically from the launch of EPA's Charles River Initiative in 1995, when the river received a "D" for meeting boating standards only 39% of the time and swimming standards just 19% of the time. The water quality improvements are due to significant reductions in the amount of Combined Sewer Overflow (CSO) discharges to the river over the past 24 years, as well as enforcement of water quality standards and removal of illicit discharges.  Illicit discharges often consist of cracked and leaking sewer pipes or improper sewer connections to the storm drain system.

While bacteria levels in the Charles have declined over time, algae blooms have become a major problem in the river. These blooms—some of which include toxic cyanobacteria—are driven by excessive phosphorus in stormwater runoff. An updated Municipal Separate Storm Sewer System (MS4) permit for Massachusetts has taken effect and will encourage further progress to reduce harmful amounts of phosphorus. The new MS4 permit will build upon past work and update stormwater management efforts across Massachusetts, better protecting rivers, streams, ponds, lakes and wetlands across the commonwealth.

"The Commonwealth is pleased to join all of the partners in celebrating these critical water quality improvements to the Lower Charles River," said Commissioner Martin Suuberg of the Massachusetts Department of Environmental Protection. "We continue to support the important work that municipalities and stakeholders do as environmental stewards in this historic and vital watershed."

"For years, the Charles River has received consistently high grades for its water quality, enabling residents and visitors with an excellent opportunity to enjoy this incredible natural resource located in the heart of the Greater Boston area," said Massachusetts Department of Conservation and Recreation Commissioner Leo Roy. "The Commonwealth continues to foster strong working relationships with local and federal stakeholders, like the Charles River Watershed Association and the US EPA, to achieve mutual goals that directly benefit the public."

"The B grade is a reminder that while the Charles is much cleaner than it was when the first grade was given- a D in 1995- our work is far from over," said CRWA Executive Director Emily Norton. "Today the biggest challenges facing the river are stormwater runoff, and extreme weather from climate change. We are pleased to be working with the municipal leaders in our watershed to implement nature-based solutions that reduce stormwater pollution while also building climate resilience as we experience more storms, more rains, more frequent drought and more extreme heat."

"It is clear from the data that the Charles, like Boston Harbor, has become a great recreational asset for all to enjoy," said MWRA Executive Director Fred Laskey. "We are pleased that the investments made by MWRA's ratepayers continue to pay dividends."

The grade for 2018 was measured by taking samples during both wet and dry conditions. During wet weather conditions, higher bacterial concentrations and poorer water quality due to sewer overflows and polluted stormwater runoff are more likely.

The 2018 calendar year saw a continuation of the expanding use of the Charles River, with the Charles River Swim and continued advocacy for a permanent swimming area near the entrance to the Charles at North Point Park. Last July, nearly 300 swimmers took part in "City Swim" off the Esplanade docks.

As collaborative efforts between EPA, state and local government, private organizations and environmental advocates continue, the goal of a consistently healthy river becomes closer to an everyday reality. For the fifth year, EPA launched a water quality monitoring buoy in front of the Museum of Science in the Charles River Lower Basin. This buoy measures water quality in near real time. The data is being streamed-live on EPA's Charles River website, as well as to a Charles River exhibit in the Museum of Science.

Citizens have been the driving force behind the Charles River Initiative, and they can continue to help improve water quality in the river while monitoring progress themselves.

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