At its headwaters, taylor creek, with its song sparrows, cedar waxwings, goldfinches and monarch butterflies flitting between native saplings, wildflowers and ripening berries, seems to spill into a bucolic vision of the future.
Standing beside it on this hot midsummer day, watching the red-winged blackbirds flying among stream-cleansing cattails and sedges, it's easy to forget that this tributary of the Don, here on Pharmacy Ave near the 401, begins its meandering from a storm sewer culvert.
Once upon a time, the stream here was entirely straitjacketed in concrete, but in the late 90s, as part of long-term restoration, the Conservation Authority ripped out the cement and replaced it with a pair of naturalized stormwater retention ponds.
Now ducks and geese lounge on willow islands while flotillas of glossy whirligig beetles patrol near shore and pairs of common whitetail dragonflies mate in the air overhead, the females afterwards dipping their tails in the drink to lay their eggs a sure sign of good water quality.
But only goldfish navigate beneath the surface, apparently dropped in, as they are in countless park ponds across the city, by locals heedless of calls by authorities to keep exotics out of natural ecosystems.
For native fish, some Toronto streams are a distant piscine dream. Storm sewer runoff, rampant development and artificial stocking for sportsfolk have wacked out the riverine ecosystem. This is in contrast to our lakefront, which, miraculously, is inching toward its former self, its fish population increasing steadily over the last 30 years.
To grasp the sad history of our waterways, consider that like other now-buried or channelized creeks that once furrowed the pre-settlement landscape, Taylor Creek was originally a cold-water brook trout stream.
The area's larger watercourses were fabled for the immensely bountiful spawning runs of Atlantic salmon that attracted Huron and Iroquois villages to their banks. But with European agricultural settlement, forests were cut to those banks, causing massive erosion, siltation and the warming of rivers, while mill dams cut off spawning grounds. The native trout and salmon soon disappeared.
With urbanization and pollution, more sensitive species such as little-known sculpins and rainbow darters, plus various minnows and others perished in many Toronto streams.
Today, stormwater runoff is the greatest threat. Because roofs and pavement cover much of the city's surface, rainwater is rapidly directed through storm sewers into waterways without having a chance to percolate into the ground. This runoff carries with it animal waste, road salt, motor oil and other contaminants.
Storms create surging flushes of warm or cold water, shocking fish and scouring and eroding stream beds, which subsequently have little to feed acquatic life during dry periods. Creeks flowing with less than 5 litres per second rarely harbour fish.
All this won't be fixed any time soon. In 2003, Toronto city council approved its billion-dollar Wet Weather Flow Master Plan, the first 25-year phase of a 100-year strategy. It includes plans to rebuild and naturalize stretches of urban streams and establish green retention ponds like those at Taylor Creek's headwaters and to construct more extensive underground tunnels to capture and treat stormwater.
But while progress may be painfully incremental, one has to be grateful for the reclamations that have been made. Deborah Martin-Downs, director of the Toronto and Region Conservation Authority's ecology division, points to records showing that before modern pollution controls were implemented in the 1960s and 70s, the North Toronto Sewage Treatment Plant one of 13 such plants that once emptied into the Don system created a deadly septic zone of effluent that stretched a mile downstream. "There was nothing living in there except rat-tailed maggots (the larvae of beeflies),' says Martin-Downs.
In the same area today, rainbow trout can be seen spawning in gravel beds in early spring. Later, in September and October, spawning runs of huge Pacific salmon from Lake Ontario move through the same waters, reaching as far north as Thornhill.
Problem is, they're foreigners in these waters and only show how disturbed the watershed really is. They are stocked by the provincial government and private organizations for the benefit of anglers. The reason they're increasingly seen far up the Humber, Don and Rouge is that the Conservation Authority has removed or modified dams, weirs and other obstructions that formerly blocked their migratory paths from the lake.
"It doesn't mean we've fixed the river,' says Martin-Downs. Despite earlier improvements in the most polluted places, she adds, all the suburban development north of Steeles and intensification within the city mean that water quality in our rivers and streams has changed little over the past 20 years.
Consequently, overall aquatic diversity probably continues to decline.
Erling Holm, assistant curator for fishes at the Royal Ontario Museum, has been tracking the decline of the sensitive redside dace in recent decades. Within Toronto, the colourful minnow, which retreats to isolated stream pools during dry periods but needs riffles (fast-moving rocky waters) in which to spawn, is now found only in Morningside Creek.
"The big problem with urban streams is that developers like to build as close as possible to the water. But fish depend not only on what's in the stream but also what's on the bank,' says Holm, noting that redside dace eat insect larvae from vegetation on stream banks.
Yet for all the battering urban waters have taken, finny life persists in far more places than most urbanites realize, a fact attested to by the numbers of cormorants, gulls, night herons and kingfishers that fan out over the city for fish dinners. Seemingly isolated ponds and reservoirs often abound in sunfish, minnows, bass and bullheads all indigenous species.
After breaking free of its concrete lining as it emerges from beneath Eglinton Avenue into a shallow, shaded ravine, Taylor Creek gradually deepens and widens, becoming more varied, wild and rocky. In Warden Woods Park, south of St. Clair, native fish several types of minnows and suction-mouthed, bottom-feeding white suckers finally begin to ply the stream.
Among the minnows, iridescent-sided creek chub sometimes leave long ridges of tiny gravel mounds where they bury their eggs at the bottoms of slow-moving pools in the creek. Their streammates, dark, speckled blacknose dace, raid these same nests, gobbling the eggs and laying their own in their stead.
All of these fish are tolerant of degraded habitats and are among the most common species found in other urban streams such as Black, Highland and Morningside creeks.
On the other hand, unlike sensitive river habitats, the more stable waters of the lake are seeing a constant increase in the number of acquatic denizens, a response to sharp falls in contaminants such as heavy metals and PCBs and to the creation by the TRCA of spawning channels, artificial reefs and wetlands.
Where pollution-tolerant carp and suckers predominated in the once-murky
inshore waters, large numbers of pike, largemouth bass and even habitat-picky walleye all native are turning the waterfront into a surprise sport fishing hot spot.
Native minnows, too, such as emerald and common shiners, as well as sunfish, are increasingly taking the place of long-dominant alien alewives and smelt as the forage base for predatory fish in the harbour, as a more natural ecosystem re-establishes itself.
Even rarities like threespine stickleback and, most recently, sturgeon are turning up. Some 35 fish species have been found in the Toronto Islands' lagoon area.
And the long-lost Atlantic salmon? It may once again throng Toronto waters. The provincial Ministry of Natural Resources has already reintroduced them in spawning rivers to the east and west of the city.