Switching Channels in Black Creek

A lot of good things came out of the 1950s: Elvis, hula hoops, Hush Puppies; channelized creeks, however, weren't among them, according to Mike Izzard.

Izzard is an environmental lawyer and engineer who chairs the Black Creek Project, a community group working to regenerate this key Humber River tributary. For the past few years he and his colleagues have been assessing ways of naturalizing stretches of Black Creek.

"After Hurricane Hazel, the engineers came in and said we've got to prevent this flooding nonsense," says Izzard. "And the easiest way to do that was to build concrete channels to carry the creeks."

This flooding solution, however, created even more problems. First, concrete only lasts about 30 years; the material cracks, water gets in and freezes, and the whole form starts to crumble. The resulting chunks of concrete create problems, but stream channeling also robs flora and fauna of habitat. As well, the channels hamper the natural processes that absorb floods and filter the water that ultimately reaches Lake Ontario.

The Black Creek Project is studying a 500 metre section of Black Creek in Etobicoke between Jane Street and Rockcliffe Road. Izzard and his colleagues are looking at what it takes to break up and remove the channels. "Almost all of the concrete can be recycled," says Izzard, "so it increases the project's potential revenues and drops the costs."

But once the concrete is out, how do you naturalize a stream bed that has been tamed for decades? According to Mike Izzard, you can just leave it the way it is and let the creek find its own course. Or you can speed up the naturalization process via the science of fluvial geomorphology , or, as Izzard likes to call it, "streamology". Streamologists assess the width and depth of the watercourse, as well as the stream bed material and expected water flow. The resulting computer model guides any engineering work, as well as the planting of shrubs with extensive root systems (like osier, dogwood and willow). "But," as Izzard notes casually, "If you make a mistake on a meander, big deal. It may wash out some of your trees, but the stream will ultimately go where and how it should. There's a sort of Zen to it all."

Public education and awareness are also by-products of this work. "People see that stream naturalization can happen, and they in turn encourage other people to start projects in their areas. It's just like Blue Box recycling: everyone said it would never happen, but they were wrong."

Since the 1950's hundreds of streams have been channelized throughout Lake Ontario's urban areas. Stream naturalization heralds the return of a natural approach to flood control, as well as ultimate improvements in water quality.

Cleaning up the Bay of Quinte one shovelful at a time (April 1997, Vol. 3 No. 1)
New Community Group Aims to Clean Up Toronto Bay (April 1997, Vol. 3 No. 1)