Don't Touch The Charles River: Toxic Algae Blooms Detected

BOSTON —Don't touch the Charles - or let your dog go into or drink from the right now. That's the message out of the Department of Conservation and Recreation Thursday, after high levels of the blue-green algae that can be toxic to humans in high volumes were detected in the Charles River Lower Basin during a recent water sampling.

This particular type of algae called cyanobacteria can be toxic if ingested in high doses and can cause skin irritation and a rash after wading or swimming. And it can be pretty smelly (runners beware).

On Thursday DCR announced a cyanobacteria bloom is present within the Charles River Lower Basin in the cities of Boston and Cambridge from the Boston University Bridge to the Museum of Science. If you see the yellow flags out near the Charles River Canoe and Kayak, that's what those mean.

Cyanobacteria blooms have been fairly common in recent years in the Charles. There were blooms reported in 2017, 2016 and 2015. Phosphorus pollution that collect on roads and parking lots, and then drains into the Charles River through the storm drains (they go straight to the river) helps the blue-green sheets of algae grow.

The state will collect water samples on a weekly basis until cell counts drop to safe levels, the DCR announced in an emailed statement to folks on their email list. An advisory generally remains in effect until cell counts drop and remain at safe levels for two consecutive weeks.

"During a bloom it is strongly advised that the public should not contact the water. Additionally, pet owners should keep their animals away from the shoreline to prevent them from ingesting the water," DCR wrote.

Lest you think this algae bloom is a blow to the years of Charles River clean up, not so. The Environmental Protection Agency grades the quality of the water these days. And the river is usually considered safe for boating and reasonably safe for swimming (about 70 percent of the time). This isn't related to that kind tests the EPA does on the water, which looks at E. coli counts.

Other than staying out of the water, there's not much recourse once a bloom is present, say officials. You just have to wait.

Patch reporter Jenna Fisher can be reached at Jenna.Fisher@patch.com or by calling 617-942-0474. Follow her on Twitter and Instagram (@ReporterJenna).