Closing the Clean Water Gap

Tackling the Biggest Threat to a Clean Charles River

An evening along the Charles is not as idyllic as it seems. For decades, the river’s biggest polluters haven’t had to clean up their dirty runoff, putting the river at risk. Photo: Paolo Braiuca CC by 2.0

By Laurie O'Reilly

Take a stroll along the Charles River on a nice weekend, and you’ll see why it’s considered one of the busiest watersheds in the country. Even at the height of the COVID-19 pandemic, joggers and walkers still threaded its shoreline paths; canoes, kayaks, and sculls plied its waters; and sailboats drifted along its currents.

But this scene is not as idyllic as it seems. Far too often these days, beautiful afternoons by the water are marred by toxic blue-green algae outbreaks. Those outbreaks don’t just smell and look bad – they can harm our health and that of our children, pets, and the fish, plants, and other aquatic life that call the Charles home.

It wasn’t so long ago that the Charles was one of the dirtiest rivers in the country. Today, thanks to CLF, the Charles River Watershed Association (CRWA), and other advocates, the Bay State’s iconic river is on the mend. But despite these decades-long clean-up efforts, we still have far to go before we can declare the Charles truly healthy.

The biggest issue facing the river today – and the underlying cause of those toxic algae outbreaks – is phosphorus pollution from stormwater runoff.

Along the river’s 80-mile course from Hopkinton to Boston Harbor are thousands of acres of strip malls, office parks, and other commercial development, along with their flat roofs and huge parking lots. “We continue to develop along the Charles and not require these developments to manage their stormwater pollution on-site,” says Heather Miller, general counsel and policy director for CRWA. “As a result, blue-green algae, which occur naturally, are growing into harmful blooms and, along with invasive species, have become unmanageable.”

Back when the Charles flowed through a largely natural landscape, rainwater was absorbed by the ground. The ground acted as a natural filter for pollutants before the water eventually drained into the river. Today, stormwater gushes off those acres of roads, sidewalks, parking lots, and roofs, picking up trash, chemicals, gasoline, fertilizer, and other harmful pollutants along the way. The result: a contaminated soup of dirty water draining into the Charles, Boston Harbor, and other rivers, lakes, and streams across New England.

A major ingredient in that soup is phosphorus, which feeds blue-green algae and causes the harmful outbreaks. Excess phosphorus also fertilizes harmful invasive species such as water chestnut and milfoil, which crowd out native plants and damage the ecosystem. Last summer, says Miller, “we saw a bloom in the lower [Charles River] basin that lasted from June to the end of the year. If we don’t get a handle on the stormwater pollution, these issues are only going to get worse.”

Stormwater pollution feeds toxic blue-green algae outbreaks that harm wildlife and degrade the health of the Charles. Photo: Charles River Watershed Association

Stormwater pollution is a preventable problem, however. With effective implementation of the Clean Water Act by the Environmental Protection Agency, this entire destructive cycle could have been halted years ago.

Properties such as commercial businesses, academic institutions, and high-density residential buildings contribute the greatest amount of phosphorus to the Charles River. But these property owners don’t have to take steps to reduce the polluted water flowing from their properties. Instead, it all gets dumped into municipal stormwater systems – leaving local governments on the hook for its costs.

“For decades, cities and towns have been footing most of the bill for stormwater pollution prevention,” says Heather Govern, CLF’s vice president for Clean Water. “It’s time the large commercial property owners and institutions that benefit from their location along the beautiful Charles be held accountable for the pollution they produce.”

It’s no mystery to the EPA which private property owners pollute the most (Harvard University and MIT, among them). The EPA has had both the legal authority and obligation to hold them accountable for decades, but they’ve failed to require them to obtain a permit that would cap the amount of polluted stormwater they could discharge.

All of that, however, is about to change.

Two years ago, CLF and CRWA petitioned the EPA to live up to its legal responsibility. Together, they called on the federal agency to control stormwater pollution from landowners with large amounts of paved surfaces and buildings.

As a result of that petition, the EPA is finally acting. The agency is now deciding the details of a permitting program that will reduce runoff from these polluters. CLF’s Govern is optimistic that by next spring, large property owners that have had a free pass to pollute for decades will be required to better control their dirty runoff – and with it, the phosphorus loads entering the river. “It is time they realize the true costs of combating stormwater pollution and share that burden with cities, towns, and taxpayers,” she says.

Govern believes this outcome won’t just be a success for the Charles. This stormwater permitting program for the Charles River watershed could set a trend for other watersheds in New England and nationwide, putting many more of our rivers, lakes, and streams on the path to being fishable and swimmable for all.