A community group wants the Halifax Regional Municipality to stop salting roads around Williams Lake near Purcells Cove Road because it says the lake is being contaminated.

The Williams Lake Conservation Company, a volunteer non-profit group that works to promote the health of the lake and its watershed, hired retired biologist David Patriquin to test salt levels in the water.

"He found that in one area of the lake it appeared that was not turning over, which is fundamental to a healthy lake," said Kathleen Hall, who sits on the group's executive and lives on Williams Lake.

"The bottom turns over and oxygen is allowed to get in there and so the plants can grow. Of course, if the lake becomes stagnant and doesn't turn over then organisms will die. There will be no fish, birds whatever," Hall told CBC Radio's Information Morning.

Road salt running into lake

Williams said high salt content can prevent a lake from turning over. Tests also showed salt concentrations were higher where runoff from a new subdivision entered the lake.

"The salts were seven times what the inputs were in the undeveloped parts of Williams Lake. So that's a really strong indication that development leads to more salt," said Hall.

Williams Lake used to have some protection; for 25 years the municipality agreed not to salt streets near the lake. Hall said last year crews suddenly began salting again, this time using a brine mixture. She said she was told the municipality changed its policy.

Hall said her conservation group is urging the municipality to once again stop the practice.

HRM following federal salting guidelines

So far Halifax has no plans to do that.

In an email, municipal spokeswoman Jennifer Stairs said Halifax follows Environment Canada's code of practice regarding the environmental management of road salts.

The code recommends using salt management plans to reduce the negative environmental impact. Stairs said negative impacts can be cut by delivering the right amount of salt, in the right place, at the right time.

If people living around Williams Lake have concerns about how salt is applied they can discuss them with the municipality or submit a petition, she said.

Hall said the group already raised its concerns with the municipality, but it hasn't led to change.

"The two parties are locked in a situation where the residents are definitely unhappy and things aren't changing, but then the city will say, 'Well, we don't know what's going on.'"