Long-polluted parts of Boston’s major rivers continue to fail EPA’s water quality ‘report card’ – The Boston Globe

Though some sections of the Charles, Mystic, and Neponset Rivers received “A” and “B” grades, reflecting safe swimming conditions much of the time, long-polluted segments stayed dirty or saw minimal improvements, according to the 2022 Water Quality Report Card, an annual report produced by the Environmental Protection Agency.

The school-style grades reflect levels of bacteria, including E. coli, in the water. An A+ grade means a body of water’s bacteria levels are in compliance with the Massachusetts Department of Environmental Protection water quality standards for swimming and boating over 95 percent of the time, while an F signifies safe levels less than 40 percent of the time.

Very few sections along the three rivers are consistently clean enough to swim in, according to the report: only Upper Mystic Lake on the Mystic River and Turner Pond, Crack Rock Pond, and Willet Pond on the Neponset received A+ grades.

Meanwhile, several sections received very low or failing grades, indicating bacteria levels that exceed safe levels 50 percent of the time or more. Many of those sections are located neighborhoods identified by the state as environmental justice communities, based on income and other demographics.

Segments within the Mystic River watershed that retained their D grades were Little River, Alewife Brook, Mill Brook, and Winns Brook, while Malden River dropped from a C- to a D, and Mill Creek scored an F. In the Neponset watershed, the Pequit, Pine Tree, Traphole, Unquity, and Germany Brooks all received D-range grades, and Meadow Brook received an F. On the Charles, the Muddy River got a C, a slight improvement from last year’s C-.

“Shame on us,” said David Cash, the EPA administrator for the New England region, at the event. He had hoped to jump into the Charles during the event to demonstrate the river’s cleanliness, but was dissuaded by the upper basin’s B rating. “We have so much more to do. This report card thankfully illuminates where the work needs to be done.”

Much of the persistent contamination comes from so-called combined sewer overflows, which can happen in towns with combined wastewater and stormwater systems. During major rainfall events, stormwater can overwhelm water infrastructure, forcing towns to divert raw sewage into rivers or risk backing up pipes.

CSOs are especially common in areas with a high percentage of paved surfaces, because stormwater runoff cannot absorb into the ground. There were 47 CSOs along the Charles in 2021, a particularly wet year, causing 126 million gallons of waste to enter the river.

Stormwater is also its own source of pollution, as floodwaters pick up contaminants on roads — including chemical residue and fecal matter — and deposit them in the rivers.

“It’s one step forward and two steps back,” said Ian Cooke, the executive director of the Neponset River Watershed Association. Despite some “success stories,” he said many of the Neponset’s tributaries are “really backsliding,” largely due to polluted runoff.

Officials also emphasized that climate change is already making cleanup efforts more challenging. Scientists have linked climate change to more intense rainfall events, which make CSOs and heavy stormwater runoff more frequent.

Despite the bleak prognosis, officials noted long-term improvements since the mid-20th century, when rivers were dumping grounds for industrial waste, and said that they’re not fighting a losing battle.

Emily Norton, executive director of the Charles River Watershed Association, said “nature-based solutions,” like rain gardens or bioswales, are effective: They make CSOs less likely by reducing the amount of water entering combined water systems in the first place. “These are basically mimicking the way that nature will manage its water by slowing it down and infiltrating into the ground, instead of sending it polluted into storm drains,” she said.

Water infrastructure improvements could also get a boost from the federal government: Markey encouraged the officials in attendance to apply for funds available through the Bipartisan Infrastructure Law.

“There are billions of dollars available,” said Norton, though she noted that local organizations have yet to decide on which projects to prioritize. “Money cannot be an excuse.”

Considering this year’s mixed bag of a report card, cleaning up the three rivers will take significant time and money, officials said.

“We should all be leaning in for the next 20 years of work,” said Patrick Herron, the executive director of the Mystic River Watershed Association. “It’s going to require a tremendous investment, a billion dollars of investment, to actually have a clean waterway that we can all swim in and boat in.”

Still, officials reiterated their commitment to meeting environmental goals.

“We must never stop fighting to ensure our waterways don’t just get a passing grade,” Markey said, but “are at the top of the class.”

Norton said she hoped the Charles would be swimmable in the next decade.

“Soon enough that people can have hope that they can do that,” she said.

Maliya Ellis can be reached at maliya.ellis@globe.com. Follow her @EllisMaliya.