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Annual Report Card Shows Water Quality Improvements in Parts of the Mystic River Watershed in 2017

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Emily Bender (

BOSTON – The U.S. Environmental Protection Agency (EPA), in collaboration with the Mystic River Watershed Association (MyRWA), announced its annual Water Quality Report Card on the Mystic River watershed for 2017. For the fourth year in a row, water quality monitoring data show that bacterial contamination in the main stem of the Mystic River, including the Upper and Lower Mystic Lakes, is very low on a regular basis and meets water quality standards nearly all the time, especially in dry weather.

"We are happy to see some improvement in certain segments of the river, indicating the work we are doing is making progress," said EPA Regional Administrator Alexandra Dunn. "There is still work to be done to improve water quality in the tributary streams, and we look forward to working closely with our partners on those efforts."

"The Mystic River Watershed deserves our ongoing attention and commitment," said Massachusetts Department of Environmental Protection (MassDEP) Commissioner Martin Suuberg. "I look forward to the continued work of local, state, federal and advocacy partners to make progress on this important resource."

"We are pleased to celebrate an A- water quality grade for the Mystic River. The Mystic meets standards for boating safety more than 98 percent of the time in dry weather, which doesn't mean that all of the work is done," said MyRWA Executive Director Patrick Herron. "EPA's system for appraising water quality stream-by-stream gives us confidence that we can document positive changes over time in areas that aren't doing as well. We look forward to celebrating the municipal investments and continued stream and lake improvements over the next several years." 

"It's gratifying to see this continued progress on the Mystic," said Fred Laskey, MWRA Executive Director.

"We are thrilled that this year the Mystic River area is receiving an overall A- water quality grade," said City of Medford Mayor Stephanie M. Burke. "Our partnership with the Mystic River Watershed Association, the Environmental Protection Agency, and the Massachusetts Department of Environmental Protection allows us to make necessary improvements to the water quality along the Mystic River. In addition, we are truly fortunate to have volunteers stewarding our watershed. The Mystic Lakes are a wonderful place to recreate, swim, canoe and kayak, or enjoy a walk along the Mystic River Reservation pathway. This is the perfect time of year to learn all that our beautiful watershed has to offer!"

The report card shows improvement in some segments of the watershed in 2017, which indicates that our work to reduce bacterial contamination may be starting to show positive changes. Since 2015, EPA has utilized an enhanced, locally-specific analysis of water quality in the watershed that gives grades for 14 river segments, including ponds and tributary streams.

While no single "overall" grade is generated for the Mystic River watershed as a whole, the data show that the main stem of the river is often safe for swimming and boating; however, bacterial levels in many of the tributary streams feeding the Mystic are high, and these areas often do not meet water quality standards. In 2017, some of these problem streams showed signs of improvement, including Belle Isle Inlet in Revere/East Boston, Meetinghouse Brook in Medford, and Mill Brook in Arlington.

There is still more work to be done. On July 1, 2018, the EPA and MassDEP updated Municipal Separate Storm Sewer (MS4) permit for Massachusetts will become effective and it will require all Mystic River watershed communities to improve their stormwater management efforts, which will help further reduce pollution.


The report card grades issued annually for the Mystic River by the EPA are based on the level of bacterial contamination found in samples collected by MyRWA volunteers over the past year at 15 monitoring sites throughout the entire watershed, as well as data collected at numerous locations by the Massachusetts Water Resources Authority (MWRA). The grades are calculated using a three-year rolling average, allowing for a more complete and accurate assessment of recent water quality that addresses weather variability from year to year.

Mystic River Watershed Water Quality Grades and Compliance Rates – Calendar Year 2017
Grade Water Segment Avg. Meeting MA water quality standards for boating and swimming
A+ Upper Mystic Lake 98.6%
A Chelsea Creek 94.6%
A- Mystic River (salt water) 88.3%
A- Mystic River (fresh water) 87.6%
A- Belle Isle Inlet 89.3%
B Meetinghouse Brook 78.4%
C Malden River 63.7%
C- Aberjona River 59.4%
C- Mill Brook 55.1%
D+ Little River 54.2%
D+ Alewife Brook 53.8%
D- Island End River 42.5%
F Winn's Brook 38.4%
F Mill Creek 31.3%

For the past several years, the EPA, in partnership with the MassDEP has had an active enforcement program focused on finding bacteria 'hot-spots' in the Mystic and tracking down the sources of that pollution. Through innovative approaches to our field testing methods, EPA has been able to find and fix illegal connections and prevent more than 42,000 gallons per day of sewage from entering the Mystic River watershed.

More work is scheduled for these tributaries. Many communities are actively investigating their discharges and are completing repairs to their sanitary and storm sewer systems, which will prevent tens of thousands of gallons more of sewage from discharging to the river during rain events.

In addition to bacterial contamination, the Mystic River watershed also suffers from excess nutrients, primarily phosphorus, entering the river from stormwater. EPA, MassDEP, MyRWA and several other partner agencies are nearing the completion of a two-year study that will help determine how much phosphorus must be reduced to meet water quality standards, and the most cost-effective means of achieving those reductions.

In support of that effort, EPA has deployed a water monitoring buoy in front of the Blessing of the Bay Boathouse in the City of Somerville capable of measuring – in real time – a host of water quality parameters including temperature, dissolved oxygen, pH, turbidity, conductance, and chlorophyll, and helps the agency track cyanobacteria (blue-green algae) blooms. Data from this buoy – and from the water quality sampling program on the Mystic River that led to the grades in this report card – can be found on the EPA's Mystic River website at (

This report card is part of the EPA's long-term effort to improve this vital waterway through support for the Mystic River Watershed Initiative Steering Committee. The Steering Committee includes EPA and MyRWA representatives, as well as representatives from other federal and state agencies, and numerous public advocacy groups and municipalities from throughout the area, and was formed to help foster a strategic, community-driven approach to water quality improvement.

More information on EPA's Mystic River Watershed Initiative, turn here: (