The Muddy River has received a D- score on The Charles River Watershed Association (CRWA)’s annual water quality report for 2020, with all other areas of the Charles River watershed earning A and B grades.

A D- grade means the Muddy River failed to meet Massachusetts water quality standards for swimming and boating for 55% to 60% of both the wet and dry seasons. The main factors volunteers looked for were the presence of E. Coli and Cyanobacteria, with a failure marked on any day the levels were high enough to pose a health risk to humans.

“You wouldn’t want to swim in it,” said Emily Norton, Executive Director for the Watershed Association. “Particularly when there’s Cyanobacteria, dogs are killed when they get in and drink the water. It’s dangerous to have contact with it and according to some studies even to breathe near it.” The annual report’s data is collected by around 80 volunteers. Once a month, samples are collected at 35 different sites and tested for hazardous elements. Muddy River has long been a problem area as one of only two tributary sites measured by the Watershed Association.

“Tributaries often have higher pollution because they lack the dilution effect of the river’s main stem,” said Lisa Kumpf, the CRWA’s aquatic scientist.

“The land use around the area is also highly urbanized, with the watershed covering Brookline Avenue and part of Newton. Several storm sewer systems go into the Muddy as well as one Combined Sewer Overflow discharge site.”

Pollution along Muddy River goes back decades and was one of the challenges the Emerald Necklace Conservancy was founded to address in 1996.

“The Emerald Necklace Conservancy was born over concerns about the Muddy River,” said Karen Mauney-Brodek, the Conservancy’s president. “There’s a real need to focus on water quality. Land and river aren’t separate, even if regulators treat them as such.”

Kumpf indicated that the main source of E. coli pollution in the Charles River watershed is storm runoff, which the CRWA hopes to counteract with beds of local plant life around stormwater discharge sites. Green stormwater infrastructure naturally filters the grey water through the soil, isolating and purifying contaminants so that the river receives clean water.

The CRWA has been lobbying local governments to alert residents of sewage releases and has set up its own alert service for poor water quality. Muddy River has also been the site of a restoration project from the Army Corps of Engineers since the late 1990s in the interest of flood control. A first phase opened up a section of the Muddy River to sunlight and air in 2016, and the current second phase consists of dredging. The process started last fall and aims to both improve filtration and clear habitat to be reclaimed by local wildlife, further filtering the water.

The Emerald Necklace Conservancy is planning to clear the last areas still choked by 15-foot-tall groves of invasive phragmites reeds after the Army Corps’ two-year second phase. It also has its sights set on daylighting Charlesgate, the connection between Muddy River and the Charles River. “The last 250 feet of the river is in a pipe from the 1950s,” said Mauney-Brodek.

“They’re old, they’re full of gunk, and the D-rating is taken just north of that, so it might be an F in the middle of those pipes.”

There could be much more work to be done around other Charles River tributaries. The CRWA’s sampling efforts only began giving its two measured tributaries discrete grades in 2019, and over 30 other tributaries go unmeasured due to a lack of funding.

“We don’t have the capacity to do sampling in every tributary. I wish we did, but we just don’t,” said Norton.