A blue-green algae bloom has developed in the Charles River by the canoe and kayak launch in Newton, the Charles River Watershed Association said Thursday in an advisory warning people to avoid contact with the water.
This is the first time in recent years that blue-green algae has been spotted in the Lakes District of the Charles River, which includes Newton, Waltham and Weston, the association said. However, there have been a number of algae blooms in the river south of Cambridge over the past six years.
The watershed association advised the public to avoid touching the water in the area near Charles River Canoe & Kayak off Commonwealth Avenue in Newton, and to wash off after any contact. The advisory does not close the river to boating, however.
“We haven’t seen a bloom like this in this section of the river before,” Kate Bowditch, the association’s director of projects, said in a news release. “There are thousands of people out on the river on these hot summer days; we need to do more to protect them and the river we all love.”
Some algae blooms can produce toxins and cause skin and eye irritation, trigger asthma-like symptoms and if swallowed in large amounts, harm the liver.
The section of the river near Commonwealth Avenue has been a deep green since Monday, and tests indicate that cyanobacteria concentration is more than twice the state’s threshold of 70,000 cells per milliliter, the association said.
The algae bloom has also probably extended down to the Moody Street Dam in Waltham and the association is awaiting test results from the water there, said Amy Rothe, the association’s spokeswoman.
Blue-green algae has been a problem this summer around the Greater Boston area, closing popular lakes and ponds to swimmers.
Last week, nine lakes and ponds were under a blue-green algae advisory, according to the Massachusetts Department of Public Health.
Blue-green algae blooms in areas with large amounts of nutrients – such as those found in fertilizers, leaking septic or sewer systems, and animal waste – and in warm temperatures.
The watershed association “believes that high temperatures combined with excessive nutrient pollution loads in the Charles are the cause of the algae bloom in the Lakes District,” Rothe said.
Mark Jacobson, general manager of Charles River Canoe & Kayak, said fewer people were renting boats at the Commonwealth Avenue landing since the advisory was issued. Some are heading instead to the company’s other locations along the river.
“Today’s definitely been quieter,” Jacobson said. A hose has been set up so that paddlers can wash off if needed, he added.
Deirdre Fernandes can be reached at email@example.com.