A Fish in the City

Leaving the west branch of Huttonville Creek, Heaton drove his government hybrid SUV north, then east. We stopped to look at the remnants of the east branch, a ruler-straight smudge of marsh grasses intersecting a farm field. Farming did not pose a threat for the redside dace when the first reports of the species were made in Ontario in the 1940s; in fact, they probably did well in streams that meandered through farm fields and meadows. But this is not true of modern agriculture. The high cost of farming, especially within the shadow of the city, requires that “idle” wetlands, once set aside as woodlots, must be drained and cultivated, that pastures must be grazed intensively, generating mud and manure, that croplands be made more productive by tile drainage systems that create flash floods and contaminate waterways with pesticides, herbicides, fertilizers and sediments. Moreover, tile drains work well only if the recipient stream bed is lower than the lowest corner of the field. So streambeds, like the one we were looking at, are typically straightened and deepened, breaking their connection to the surrounding floodplain.

But if the geometrically shaped remnants of the east branch of the creek were depressing, much worse was yet to come. When Heaton turned south, the fields beside us gave way to an ecological disaster. Heavy machinery had stripped and piled the topsoil from a tract of perhaps 40 hectares and sculpted the underlying clay into a road grid, awaiting the installation of storm sewers, pipes and conduits. Black filter fabric for capturing silt from the runoff hung from an old wire farm fence that defined the boundaries of the property.

“This is the first assault on the redside dace, this grading of the land,” said Heaton. “All the water that lands here will go into Huttonville Creek. In a perfect world, someone would come around and clean that filter fabric once a week so it does a better job, and the houses would get built and the land would green up in a short period of time. In reality, the amount of sediment that comes off these sites is just phenomenal.

“The second wave is the impervious ground cover. When this is all developed, you get all the water that runs off the roads and rooftops exploding into the creeks.”

Beside the road on a small billboard, a map of the community- to-be suggested that more than 50 percent of the development will be impervious, covered by roads, parking lots, driveways, tennis courts and roofs. The rain that lands on these surfaces will become runoff, laden with pollutants and sediment. It will pour into storm sewers and inevitably into Huttonville Creek, causing flooding and erosion. Municipal building codes generally require builders to intercept runoff in stormwater management ponds, which at least slow down the torrent, allowing some pollutants and sediment to settle out. But such ponds often overflow. Watershed managers agree that no watershed can be ecologically healthy if about 10 percent of its ground cover is impervious. The obvious solution is to increase the ratio of pervious land in the community, thereby creating a pleasantly “green” community with an abundance of parks and wilderness areas. But such green areas aggravate the most acute problem associated with suburbs: greater internal distances mean more roads, more cars, less efficient transit systems and more parking lots.

Dena Lewis, manager of terrestrial and aquatic ecology for the Toronto and Region Conservation Authority, struggles with that conundrum. “I feel like I’m a juggler most of the time, and I’m just waiting for the ball to bounce off my forehead,” she says. “I don’t mean to belittle the importance of the redside dace, but if we protect it passively by not allowing development in catchments that contain the dace, then what does that do to the rest of the natural heritage system? We just push all the development out into other areas.”

One potential solution that Greater Toronto Area conservation authorities are now examining is a strategy known as “low-impact development” (LID), which mimics the capacity of a forest or wilderness area to reduce runoff and filter water through the soil. By one estimate, 17 percent of rain that falls in a forest never reaches the ground, evaporating directly off the canopies of trees. Forests also return water to the atmosphere through transpiration and hold it in the leaves and soil on the forest floor. So the first goal of LID technologies is to reduce stormwater volume, and the second is to keep it out of streams and rivers.

Properly designed green roofs can retain most or all of the water that falls on them. “Rainwater harvesting” is current jargon for cisterns and rain barrels that capture and delay rainwater to significantly reduce runoff. Green parking lots replace asphalt and concrete with permeable and semi-permeable materials that allow stormwater to soak into the soil, where beneficial microbes can break down pollutants. In Minnesota, rain gardens that homeowners maintain were found to reduce runoff by about 90 percent, while a “green street” project in Seattle, which replaced 11 percent of the impervious street cover with soil, trees and shrubs, realized a 99 percent reduction in stormwater runoff. Such technologies are not hugely expensive and help pay for themselves by reducing the amount of land that must be set aside for stormwater ponds.

Provincial conservation authorities feature such LID technologies prominently on their websites, but no significant project using them has yet been implemented in Ontario. The redside dace, with its new status as endangered, may change that by giving more power to watershed managers in their dealings with developers.

But Jim Robb, a former member of the provincial Environmental Assessment Board and co-founder of the Friends of the Rouge, which has challenged development in the Rouge River watershed, is sceptical that the COSSARO designation – and its stipulations – will make any difference. “We already have strong provincial policy statements that say all developments must enhance water quality,” he says. “But the reality is that everywhere we’ve developed, we’ve harmed water quality and increased flooding and erosion. If we keep on doing that, the redside dace will be gone.”

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David Lees is a Toronto writer who has written extensively about science and the environment. This is his first article for ON Nature.

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