For the first time, a bloom of blue-green algae, or cyanobacteria, has caused the closure of a Gatineau Park beach.

On Wednesday, the blue-green algae bloom had dissipated, the NCC reported, but O'Brien Beach will remain closed for at least 10 days if tests for toxic cyanobacteria come back positive.
(CBC)

National Capital Commission officials were to be at O'Brien Beach at Meech Lake Wednesday morning to answer public questions about their decision to close the beach Tuesday after cyanobacteria were found at its edge, a news release said.

The bloom had dissipated by Wednesday, said Kathryn Keyes, spokeswoman for the NCC, the federal agency that manages the park.

While the beach is closed, Quebec's Parks and Environment Ministry will evaluate the cyanobacteria samples to determine whether they are a kind that produces harmful toxins.

The tests are expected to take five to 10 days.

If toxic cyanobacteria are found, the beach will remain closed for at least 10 days, which is the length of time Quebec regulations require it to remain without an observation of blue-green algae before it can reopen, Keyes said.

Otherwise, it can reopen as soon as the ministry receives a negative test result.

Cyanobacteria are microorganisms that grow in warm, slow-moving water, sometimes blooming and forming "pond scum" on the surface of the water.

A sign at the beach warns the public to avoid contact with the water if it is green.
(CBC)

Some kinds produce toxins that can irritate the skin and eyes of people who swim nearby, or cause symptoms such as fever or headaches if ingested in large quantities.

Another Meech Lake beach, Blanchet Beach, remains open to swimmers.

This year, a record number of Quebec lakes have been reported contaminated by cyanobacteria, leading to dozens of drinking water bans. The problem has been called a crisis by Environment Ministry officials.