It took $500 million and nearly two decades of work. Here's how the city did it.

For half a century, the polluted waters of the Charles River have been accepted as fact in Boston. A 1966 rock and roll love letter to the city put them at the center of the city's mythology. (The chorus? "Well I love that dirty water. Boston you're my home"). That Beantown anthem is the Red Sox victory song in Fenway Park.

In 1995, the Environmental Protection Agency began giving an annual report card for the Charles. It's first grade? A D.

But something is changing. By 2012, the river earned a B+, according to William Walsh-Rogalski, an attorney for EPA's Boston-based Region 1. It's even clean enough, apparently, to swim in. Last Saturday, the Charles River Conservancy hosted the first recreational swim in the Charles River since public swimming was banned in the 1950s.

In groups of about two dozen, 144 swimmers jumped off a dock along the city's Esplanade park and splashed around in an enclosed swimming area.    

Topher Baldwin/Charles River Conservancy

So how did the river get clean enough? Mostly, Boston stopped pumping sewage into it. 

Historic infrastructure in older cities like Boston makes cleaning local waterways a real challenge, Walsh-Rogalski explains. When the EPA launched the Clean Charles Initiative in 1995, the agency and several local non-profit partners found that there were problematic connections between the pipes that carried sewage and those that were meant to carry clean rainwater out to the river. 

In much of the Boston area, the EPA found that these were, in fact, the same system. Local sewage infrastructure had been built in the late 19th or early 20th centuries, long before the environmental movement began efforts to clean up public waterways. When water levels were low, all of the liquid in the system -- both sewage and rainwater -- flowed harmlessly to be cleaned at a treatment center on Deer Island in Boston Harbor. When a major rainstorm hit, however, these systems got backed up. Everything in the pipes, sewage and all, would flush directly into the Charles and its tributaries through older drainage pipes that now violate the federal Clean Water Act.

Early clean-up efforts began in the late 1980s following major litigation surrounding the environmental impact on Boston Harbor. In the years before these projects began, Walsh-Rogalski says there were 1.7 billion gallons of this sewage-rain mix dumping directly into the Charles. Over the last few decades, EPA-enforced renovations to municipal sewage systems have reduced that number 99.5 percent.

These re-investments in local sewage and drainage systems show in the measurements taken by the Charles River Watershed Association, a local non-profit that has partnered with the EPA. The CRWA and their team of volunteers conduct monthly readings on the bacteria levels at 37 locations along the length of the Charles. During the summer, these volunteers do twice-weekly checks at spots along the last ten miles of the river, which flows through major recreation areas in Watertown, Cambridge, and Boston. One Cambridge resident has even earned the nickname "The Mad Kayaker" for his sleuthing for illegal sewage drains along the lower parts of the Charles. 

Clean water standards for human recreation are determined by regular readings of levels of E. coli, a bacterial class that experts say is a good indicator of the presence of waste (toilet water, sewage, and all that comes with it). Some level of E. coli is expected from animal droppings, but the EPA has also tested for pharmaceuticals, another clear indication of human contamination.

"People would always say it’s the beavers or the rats. Every municipality had a different animal they would blame it on," Walsh-Rogalski says. "That's why we also measure things like Tylenol and caffeine. There’s correlation where you see those things." 

To be safe for swimming, water must have less than 126 colony forming units of E. Coli per 100 milliliters of water. The standards for safe boating are five times higher. When that nearly-failing D grade was first published in 1995, the part of the river that flows through Boston and Cambridge met boating standards 39 percent of the time and swimming standards an abysmal 19 percent of the time. In 2011, the river was rated safe for boating 82 percent of all days and swimming 54 percent of the time. The overall EPA grade for the last 10 miles of the river is calculated from a composite of daily forecasts and monthly readings. It has hovered for the last few years around B or B+, which many say is the best they can hope for for such an urban river. 

It's hard to compare these Boston-based numbers to rivers in other major American cities, mostly because the EPA's Boston office is the only one that gives out letter grades. What began as a publicity stunt to draw attention to the dire situation in the Charles has become a nearly 20-year tradition, tracking the progress of environmental efforts in the area. The Boston office recently began grading the Mystic River in suburban Boston (currently a D) in hopes of bringing similar reinvestment efforts. Even without this easy comparison, Walsh-Rogalski says he wouldn't be surprised if the Charles ranked as one of the cleanest urban rivers in the country.

And last weekend, this progress was on display. Though the river has hosted a one-mile, competitive swim race for the last few summers, this was the first time swimming was open to the general public. It took the Charles River Conservancy, a local nonprofit that has made a "swimmable Charles" a major priority, several tries to get the right permits in place for the public swim. Those involved in the river clean-up say they hope these public events will draw attention to the progress already made and the work still to be done.

"Part of this has been the psychology of changing people’s view of the river. When it’s a sore, people said why spend money on it," Walsh-Rogalski told me. "If they can start doing these swims, eventually there might be a permanent beach established. We can change the psychology so people start demanding access to the river regularly."

Julie Wood, a Charles River Watershed Association scientist who oversees the bacterial testing programs, was one of the nearly 150 swimmers last weekend. While a regularly swimmable Charles is still years away, she says she would look forward to a public beach in Boston or Cambridge.

"It just felt like a nice jump in a very refreshing lake or river," Wood says of her quick dip off the Esplanade. "I took a shower after I got out, but there was no 'ick factor.'"

Top image: Brian Snyder/Reuters

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