Yeah it's a pollution disclosure thing, to avoid people unknowingly building on landfills or warn people whose houses already are. Not sure how common it is elsewhere, I know both Montreal and Ottawa do it. I've never looked for other municipalities' maps, I suspect it's more common for larger cities which have the resources to try to figure out where these dumps actually are.I have never encountered that. Is it a Canadian thing? Or, is it done for environmental/pollution potential disclosure?