Does antifreeze harm the lake?


I use RV antifreeze to winterize my inboard/outboard. I’ve heard that in the spring, some people discharge it directly into the lake. Is this harmful? —Norma Goodger, via e-mail

Well, it’s certainly not helpful. “The quantity of antifreeze being talked about here would probably be insignificant, but it’s unnatural in a very localized way,” says John Casselman, an adjunct professor in the biology department at Queen’s University. It’s like we all learned as toddlers: Don’t stick stuff where it doesn’t belong. “If it didn’t come from the water, you shouldn’t put it into the water,” says Casselman. “That’s a heckuva good rule.”

Monica Nowierski, an aquatic risk assessment scientist with the Ontario Ministry of the Environment, says that, along with immediate, local effects to the lake—some dyes in the antifreeze may cause the water to change colour, for example—there are secondary effects. “Anything that gets into water undergoes a degradation process,” she explains. This degradation depletes oxygen levels in the lake, leaving less for the aquatic life. “It would be frightening if everyone on the lake started doing this,” she says.

Bob Eaton, the director of environmental services for Boating Ontario, suspects that boaters may feel that propylene glycol (RV antifreeze) is okay for the water because it’s less toxic than ethylene glycol (common in internal combustion engines). “It still shouldn’t go in the lake,” he says. “People say, ‘But it’s non-toxic!’ and I say, ‘Well, drink a glass of it, then.’” Good point.