Wicked Awesome Remediation

July 13, 2013 in Boston was a day more than 50 years in the making, as the long-suffering Charles River was opened for recreational swimming. Infamous for its heavy pollution, the river had become the butt of many a joke, and deservedly so. It sounds like jest to say that anyone who fell in the river was advised to go to the hospital for a tetanus shot, but that was exactly the case. After receiving a “D” grade for water quality by the U.S. EPA in 1995, the Charles began a steady road to recovery that resulted in a “B+” in 2011. And this summer, after half a century, it was once again open to swimmers — and swim they did.

This is a success story that bucks the trend for most urban waters. The U.S. Geological Survey (USGS), in the very same week the Charles River reopened to swimmers, reported that stream health deteriorated in the vast majority of agricultural and urban areas. Their study noted the following statistics:

• Two-thirds of U.S. estuaries can no longer support healthy fish communities due to nutrients and dead zones.
• 42 percent of the streams were poor or degraded compared to regional reference conditions.
• 80 percent of urban waterways contain at least one pesticide detrimental to aquatic life.

But, again, this is a success story. Urban and agricultural conditions, though difficult, are not death sentences for streams. The USGS study points out that nearly one in five of the streams situated in urban/agricultural areas was in relatively good health, despite contending with the challenges of land and water-use development that often lend themselves to poor water quality. For the Charles River to be the exception — of all places, with its history — is a monumental upset (to draw on sports parlance).

It was also quite a comeback. The Charles was once considered “an open sewer,” according to a 2011 news article from the Beacon Hill Times. And yet the purpose of the article was to announce that the river had just won the “largest environmental prize in the world,” the International Riverprize, beating out more than 20 worldwide contenders.

Wastewater Practices And Pollution Prevention
The Charles River was revived with a multifaceted game plan to address the root causes of the pollution. Some efforts, like eliminating combined sewer overflows (CSOs) and stormwater runoff, as well as aggressively monitoring water quality, are familiar and expected. Others, such as computer modeling and “smart sewering,” indicate a more advanced approach. As a practical measure, a dam was also built to prevent salt water that derives from road de-icing, wastewater effluent, and/or faulty septic systems from entering the basin.

There was one method, however, that was highly unusual. Oysters, it seems, love to eat sewage. So, back in 2008, the Massachusetts Oyster Project shipped in 150,000 of the hungry shellfish to feast in the Charles River. Speaking of comebacks, oysters were once prevalent in the Boston area, but were wiped out due to overharvesting and industrialization in the early 1900s. Now they were brought back to save the river.

With each oyster capable of filtering 30 gallons of water per day, it was estimated that 3 million gallons of sewage could be processed every 24 hours. Nitrogen, in particular, fixes to their shells, making up about 8 percent of their total weight. Apparently thriving, the oysters are still there today — a quirky piece of a puzzle assembled rather nicely by the Charles River Watershed Association and its partners.

In a time when many rivers and streams are becoming even more endangered, the reclamation of the Charles River is cause for celebration — particularly for that first group of swimmers on July 13. No tetanus shot required.