The Charles River in Needham is having quite a summer. Blue-green algae and toxic cyanobacteria has sprouted due to warm, stagnant water and nutrient-rich (primarily fertilizer) runoff, leading to the death of a West Roxbury family pet who just wanted a drink. Water flow has been changing — safely — as just upstream in South Natick a construction crew removed the generations-old dam near the intersection of Pleasant Street and Route 16, a project conservationists say is good for the river but has led to dismay among people who liked the pond it formed. And prior to the algae outbreak, teams of volunteers pulled bags full of invasive water chestnuts that had grown in the water, changing the water flow and narrowing the open channel for kayakers and wildlife such as fish.
Approximately 15.5 miles of the Charles borders Needham, forming most of the town’s boundary. To Julie Wood, director of Climate Resilience at the Charles River Watershed Association (CRWA), it’s important to understand that “if you live in the watershed, everything you do outside, a lot of things you do on your property and in your neighborhood, a lot of things your community does will impact the river.”
In addition to most Needhamites, many Boston-area residents live in that watershed. The entire river is about 80 miles long, winding in every direction from its source in Hopkinton to its (dammed) outlet into Boston Harbor near the Museum of Science. A molecule of water starting at the source, said Wood, takes about four days to make the trip to the harbor. Her organization, along with many government and civic partners, is trying to protect those molecules from mixing with natural or artificial pollutants, invasive plant life and natural threats like the cyanobacteria that likely led to the death of Elivia Savadier Sagov’s 16-year-old dog, Dobby, last month.
“She took [her two dogs] out in Millennium Park,” said Wood the morning after the incident, “and I guess they went in the water a little bit, but also drank the water. And then they both got really sick and one of them died. She got in touch with us and then we got in touch with Public Health, and as soon as they heard the story, they issued a precautionary warning.”
Toxic blooms have been relatively rare in the upper Charles, which is all of the river above the Watertown dam, Wood said. But conditions like drought, hot days that warm the water, and extra phosphorus can make them more likely — and those conditions are increasingly common.
“Plants and natural algae like really hot, really stagnant water,” said Wood. “That’s when the cyanobacteria can just outcompete everybody.” Decades after the clean water laws of the 1970s led to a much cleaner, even swimmable, Charles with no new industrial pollution (old pollutants still rest under the silt at the bottom of the river), climate change is now a threat to the river’s health.
Limiting the impact of humans, Wood said, can help. Although people have stopped adding industrial waste to those traveling molecules, our roads, cars and landscaping activities still have a considerable effect.
“We’ve really changed the natural hydrology. When it rains in a forested area, most of the water goes into the ground. We’ve paved over things or built on things, and the water can’t get through to the ground anymore. So it hits our roofs, it hits the parking lots, and it runs off, picking up pollutants as it runs over those surfaces. Then it goes straight into the river without any treatment.” She said many people believe stormwater drains lead to water treatment facilities the way sewer systems now do, but that’s not the case. “It’s really going to the closest stream or river.”
In fresh water, Wood said, the nutrient to worry about is phosphorus. Some of it is natural, from dirt and leaves that get washed into the river. But much of it comes from fertilizers, detergents, even car exhaust that lands on the roadway and is carried into storm drains.
Then there’s bacteria that may enter the stream from pet waste that is not picked up. Downstream, in the Lower Charles (though not in Needham), human sewage enters the river when especially large rains cause old sewage infrastructure to overflow.
The good news, Wood said, is that people have taken much more responsibility for the health of the Charles and are actively working to improve it. Over the past few decades, it has gone from a dangerous, chemical-filled waterway to a prime destination for recreation and a much improved habitat for plants and animals.
A larger-scale initiative to preserve and restore the health of the river is dam removal, which improves water flow, potentially reducing the time those molecules will spend on their travels. In Natick, the town was facing a multimillion dollar repair to the structure of the South Natick dam, and chose instead to remove it. The work began in July, and the dam is down and construction crews are creating a permanent channel for the water. But the major change is to the park and riverbank where the old structure stood, not to the flow of water in Needham.
Other efforts are underway to move water outlets to natural filtration areas like wetland grasses that retain fertilizers and engine waste, keeping them from reaching the river itself.
Volunteers are helping to keep the river as a more natural habitat by removing invasive, clogging plants. Wood recently spent a day at the Charles River Peninsula property in Needham, working with a volunteer team to pull water chestnuts from the river. “They can get a lot in two hours,” she said.
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