Montreal

Bromont to use clay mixture to stave off blue-green algae growth

Bromont environmentalists are hoping a $650,000-project will rid a local lake of dreaded blue-green algae.

Treatment cuts off algae's food source

Microscopic algae cells come together to form a bloom — a green, soupy layer on the water's surface. (Submitted by: University of Alberta)

Bromont environmentalists are hoping a $650,000 project will rid a local lake of dreaded blue-green algae.

About 175 tonnes of Phoslock, a product developed in Australia and made of clay and lanthanum, will be dumped into Bromont Lake either this fall or in the spring.

As it sinks to the bottom of the lake, the clay mixture traps phosphorous, the mineral that feeds the algae. 

Phosphorus gets into water in numerous ways including pollution from sewage and septic fields, runoff from agricultural fields, lawn and garden fertilizers and leaking septic tanks.

"We're fertilizing our lakes, which is creating these blooms," said Anne Joncas, president of a local environmental group pushing for the plan.

A familiar problem in Quebec

Algae, also known as cyanobacteria, have been a problem for Quebec lakes for nearly five decades.

The microscopic algae cells come together to form a bloom — a green, soupy layer on the water's surface that can sometimes be seen from space.

A number of Quebec beaches and lakes, including Lac Bromont, have been temporarily closed over the years because of algae infestations.

Algae, also known as cyanobacteria, have been a problem for Quebec lakes for nearly five decades. (CBC)

Algae deprives the water of oxygen, which affects plants and animals, and emits a foul odour. Algae also have potential to become toxic, Joncas said.

Tests conducted on other bodies of water that have been treated by Phoslock show no toxicological effects on humans, plants, animals, Joncas said, adding European lakes that first used the clay product in 2006 haven't seen new algae blooms since.

Quebec's Environment Ministry approved the project, which will be the first time Phoslock is used in Quebec.

The city will contribute $300,000 to the project; organizers have to raise the rest and have met with provincial and federal politicians as well as local companies to explore their options.

with files from CBC's Quebec AM

now