TORONTO (Reuters) - A river runs through it -- wide, deep, cold and ancient
-- and few people in Toronto suspect it's even there.
There's an ice-age river flowing deep under Canada's largest city. There has
been for at least a million years but it wasn't until last month that anyone saw
any real evidence of it.
The discovery of the glacial river happened when workers were trying to cap two
artesian wells, part of a stormwater runoff project in High Park, one of the
city's largest parks, near the shore of Lake Ontario.
One well was capped, and then, as the other was being capped, the first well
blew off like a broken water main, spewing water 15 feet into the air.
As that cap was being repaired, the second blew off, shooting up water and
Consultation with experts confirmed the workers had siphoned into the rumored,
yet still largely unknown, Laurentian River system running underneath the city.
"We've discovered where it probably comes out into Lake Ontario," said an elated
Bill Snodgrass, senior engineer responsible for groundwater quality management
for the city of Toronto. "What we never really knew before was where it
connected to Lake Ontario."
The existence of a bedrock valley was first documented in the first half of the
century, but its exact location remained largely unknown, said Steve Holysh, a
hydrogeologist working on the project.
It was likely formed one to five million years ago when layers of debris carried
by glaciers covered up the bedrock valley.
In tests done in August, researchers at the High Park site expected to hit
bedrock at about 40 feet, but it wasn't until a depth of 123 feet that they hit
the river system, technically known as an artesian aquifer. They hit bedrock at
The water flows extremely slowly in a sand and gravel stratum, which could be a
20- to 30-foot layer on top of bedrock.
It would take thousands of years for the water to travel to Toronto from the
groundwater system's origin. City hydrogeologists say the Laurentian travels at
the stunningly slow rate of about one centimeter a year.
It's origin is likely near Georgian Bay, about 93 miles north of Toronto.
The water is drinkable, but it tastes distinctly of iron, and the city of
Toronto has no plans to tap the underground river as a source of drinking water.