Are we salting Williams Lake to death?

Study suggests immediate impact from January 2015 switch from sand to salt

by Miles Howe

A top place to swim in the Halifax area. But nobody likes an anoxic bottom on a dimictic lake! [Photo: meddygarnet via Flickr]

KJIPUKTUK (Halifax) -- Since the late 1980s, the roads near Williams Lake, in the Halifax municipality, have been treated with sand and grit in the winter time, rather than road salt. There was real concern, leading up to this point, that road salt applications were running into the lake, and cause the deeper portions of the lake to anoxic, or largely devoid of oxygen.

This is a big deal, because while dimictic lakes like Williams Lake and Colpitt Lake will mix their deep to shallow waters twice a year, when an anoxic, salty bottom is created, that silty layer can simply stay there, and no longer refresh itself.

Replacing salt with sand and grit seemed to gradually rehabilitate Williams Lake, that is, until last January, when the city again began to apply road salt to the surrounding roads.

David Patriquin, a retired biology professor, took a series of deep water samples from Williams Lake last December, and what he found was surprising, even to himself. The lake had not fully turned over last fall and there was an anoxic layer at the bottom of the lake. While the tests were not conclusive, Patriquin sees the connection between the resurgent road salt applications.

For more information, I spoke with David Patriquin about his recent study, which can be found here in its entirety.  

Due to the shoe-string nature of our website, you can play the attached audio interview on your laptop or computer, but not on a tablet or phone. If it doesn't appear, don't worry, it's there. Just wait until you get to your computer to listen to the interview.

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