Blue-Green Algae Blooms Reported in Charles River

BOSTON, MA — A group that monitors water quality in the Charles River on Tuesday confirmed the return of cyanobacteria, aka blue-green algae, in the Charles River Lower Basin downstream of the Massachusetts Avenue Bridge.

According to the Charles River Watershed Association, testing done last Thursday came back positive this week, confirming that concentrations of the bacteria exceed 70,000 cells per milliliter of water, the Massachusetts Department of Public Health's water quality standard. According to the CRWA, an EPA-operated monitoring buoy near the Museum of Science also recorded a spike in phycocyanin, an indirect measure of cyanobacteria, on Saturday.

The Department of Public Health is testing the Charles River again Wednesday, a CRWA spokesperson told Patch.

"Public health officials recommend that people and pets avoid contact with the water in this area and rinse thoroughly in the event of contact," CRWA's blog post says.

Concentrated amounts of cyanobacteria in water can make the water look green and "paint-like," the CRWA said, potentially irritating the eyes, ears, and skin of people, pets, and wildlife that encounter it.

"Because cyanobacteria are most likely to release toxins as they die off, the health risks persist for about two weeks after cell counts decline to safe levels. In addition to the public health risk, by preventing light and oxygen from entering the water, cyanobacteria can smother fish and other aquatic organisms," the blog said.

As to why the bacteria didn't appear sooner, CRWA Executive Director Bob Zimmerman has an idea or two.

“The likely reason we did not see a cyanobacteria outbreak earlier in the summer is because of the severe drought,” he said in a press release.

According to U.S. EPA, the relationship between high phosphorus levels from stormwater discharges to the Charles and the proliferation of cyanobacteria is well-established, the press release said.

For tips on reducing risk from the blooms, in addition to more background on what causes the blue-green algae, visit the CRWA website here.

>> Photo courtesy CRWA