Climate

Bacteria Levels In Boston’s Charles River Spur Health Warnings From City Officials

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Just when it seemed like Boston’s chronically-polluted Charles River had made a miraculous turnaround, an algae bloom is forcing residents to avoid the river once again.

On Thursday, health officials announced that an algae bloom had sprouted in the Lower Charles River Basin, causing concentrations of bacteria in the river twice the recommended limit, according to the Boston Globe.

The algae is known as cyanobacteria — a type of aquatic bacteria that gets its energy from photosynthesis — and is common in United States’ lakes and rivers during the summer months, when warm temperatures and lots of sun help it proliferate. Unlike the algae bloom in Lake Erie that shut down Toledo’s water supply for days last summer, Boston’s algae bloom doesn’t appear to be toxic, according to the director of the Massachusetts Department of Public Health’s Environmental Toxicology Program.

“You’d have to consume an appreciable amount of that water to get ill,” Marc Nascarella told the Boston Globe.

The Charles River didn’t always used to be safe for swimming — for years, the river was so polluted that public swimming was actually banned. Used as a power source for New England’s manufacturing industry in the late 1800s and early 1900s, the industrial mills, dams, and settlements all dumped their waste into the Charles. For much of the 20th century, the river was also polluted by old pipes that carried sewage and rainwater at the same time. When water levels were low, this wasn’t a problem — but during a storm or heavy rain, the outdated infrastructure couldn’t handle the increase in volume, and flushed both sewage and storm water out into the Charles River. Beginning in the late 1980s, extensive sewer system renovations helped reduce the amount of sewage that flowed into the river with rainwater.

But even with marked progress in the health of the river — it passed the EPA’s bacterial water quality standards last year 65 percent of the time for swimming and 91 percent of the time for boating — Thursday’s news is a reminder that even with improvement, the river’s health can fluctuate day to day.

“With the Charles, it can change in a day,” Julie Woods, project director for the Charles River Watershed Association, told the Boston Globe. “Let’s clean it up, so it is made to swim all the time.”

This particular bloom, Nascarella told the Boston Globe, probably has more to do with climate change than the health of the Charles. Massachusetts has issued 150 advisories for algae blooms since 2009, and 11 of them have involved the Charles River.

Algae blooms are becoming increasingly common in bodies of water around the globe, as warmer temperatures and increased nutrient runoff (largely from agriculture) fuel their growth. And they’re expected to get worse with climate change, as more frequent heavy storms wash fertilizer into bodies of water and overwhelm pipes that carry both storm water and sewage.

A recent report conducted by scientists from Oregon State University and the University of North Carolina found that blooms of toxic cyanobacteria pose an increasingly pressing threat to the United States’ drinking water. Not all cyanobacteria produce toxins — but those that do, especially when found in high concentration, can cause skin irritation, gastrointestinal illness, and liver damage, as well as fatalities in pets, wildlife, and, in rare cases, humans.

“The biggest health concern with cyanobacteria in sources of drinking water is that there’s very little regulatory oversight, and it remains unclear what level of monitoring is being voluntarily conducted by drinking water utilities,” Tim Otten, a postdoctoral scholar in Oregon State University’s Department of Microbiology, said in a press release.

Boston health officials stressed that the bloom currently present in the Charles doesn’t appear to be toxic, but cautioned against drinking water directly from the river and to rinse off directly after contact with the water. Nascarella told the Boston Globe that most algae advisories last about two weeks.