Russell Vaughan has his ear to a storm drain and a smile on his face.
"You hear that?" he says to the people around him, who strain their ears to listen over the roar of water rushing below. "That's your lost river."
Mr. Vaughan is one of about 20 people who lead tours of Toronto's forgotten rivers, the not-so-quiet ghosts that come out to haunt the city after heavy rains. Otherwise known as the Don River watershed, the flow starts at the Oak Ridges Moraine and spans 360 square kilometres, ending 38 kilometres south in Lake Ontario.
The Lost Rivers Walks were created by the North Toronto Green Community and the Toronto Field Naturalists about five years ago. The next one is a five-hour day hike along a long-buried downtown stream, Taddle Creek, which has been regenerated in parts. The July 16 tour starts at Wychwood Ave. and St. Clair Ave. West, at 11 a.m.
Now filled in with garbage, paved over with asphalt and directed into sewers, this and other lost rivers can mostly be traced by the many dips and ridges around Toronto.
Most Torontonians only notice the buried rivers during times of heavy rain. Flooded basements, washed-out streets and foundation damage are all good reasons to start paying attention to the watershed when we develop land, Mr. Vaughan said.
"We have to find the paths of these rivers, to understand changes in the hills and valleys in which we build our homes," he said during a recent walk through Riverdale.
Alarmed at the water seeping into clay foundation sites near her home at Greenwood Avenue and Dundas Street East, English teacher Robin Osemlak joined the Riverdale walk to learn more.
"If you go up a little from [my]area, it's an old landfill there and it seems that you'd be getting 100 years of landfill seepage coming through," she said, as she strolled through a sunny glade. "God knows what's in the water."