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The Moraine

photo - hills

The Oak Ridges Moraine is a landform unique to southern Ontario. One of Ontario's largest moraines, the Oak Ridges Moraine extends 160 kilometres from the Niagara Escarpment in the west to the Trent River system in the east, and is on average 13 kilometres wide. One-hundred-and-fifty metres deep, the moraine stands out as one of the most distinct landscapes of southern Ontario. Its height above the flat lands to the north and south, its rolling hills and river and stream valleys and large blocks of mixed forest provide solace and a sense of connection to the people who live, work and play on the moraine, natural and wild habitat for flora and fauna, and untapped recreational opportunities.

However, the Oak Ridges Moraine is more than just a beautiful landform feature with its breathtaking vistas, rolling hills, wooded valleys and 'kettle' lakes. Its most precious feature lies hidden below the ground surface.

photo - stream

One of the moraine's most important functions is as a water recharge/discharge area - sustaining the health of the many watersheds, which originate in the moraine and directly providing drinking water to over 250,000 people. It has been described as southern Ontario's rain barrel - its permeable sands and gravels absorb and collect precipitation, which slowly recharge the deep aquifers below the ground.

These sand and gravel aquifers store, filter and release this groundwater to over 65 watercourses flowing north and south into Georgian Bay, Lakes Simcoe, Scugog, Rice and Ontario. At the same time, unprecedented human exploitation of this groundwater places the moraine in a precarious ecological position.

The 1991 Oak Ridges Moraine Planning Study, which began as a tightly focused land use planning exercise, became a catalyst for innovative water resource studies. The Ontario Ministry of Natural Resources, through the planning study, undertook a broad hydrogeological review of the Oak Ridges Moraine. This led to the involvement of the Ontario Geological Survey and the Ontario Ministry of the Environment in developing detailed geological and hydrogeological mapping. In 1993, the Geological Survey of Canada initiated an extensive five-year Oak Ridges Moraine study. The result of this collaborative work is an extensive 'regional scale' understanding of the Oak Ridges Moraine, exceptional by Canadian standards.

photo - lake

Despite the focus of the Geological Survey of Canada and its call for integration of land- use planning and groundwater management, municipalities and the provincial government continued to carry on with business as usual - processing applications for development and official plan amendments in the absence of a comprehensive groundwater management strategy. Land-use changes, primarily the building of residential subdivisions, the construction of roads and the paving of parking lots increase the imperviousness of the ground surface, stopping water from entering the hydrologic cycle. Consequently, this surface runoff results in dramatic increases in wet weather flows of the headwater streams on the moraine causing erosion and degradation of these fragile systems. Urban and rural contaminants entering the ground today can remain undetected for many decades given the excruciatingly slow movement of water through the ground. Water-taking, associated with these new land uses, further exacerbates the pressure on the resource. Not only is precipitation blocked from entering the ground but more water is being removed. Municipal water supplies, golf courses and commercial water-bottling companies have, by necessity, began to 'go deeper' into the moraine to find adequate quantities of drinkable and usable water.

photo - iris

We have learned over the past several years that we must proceed cautiously - how we use the moraine's land surface and its water resources can affect the deep regional groundwater flow systems, which are integral to the ecosystem health of south-central Ontario.

The Oak Ridges Moraine:
A Provincial Treasure

Soaring north from Lake Ontario's northern shoreline, the landscape below leaves behind the tall office buildings and dense residential streets of Toronto's heart, passes over suburban sprawl of subdivision and industrial parks and development coalesces along major roads and unseen pipelines that penetrate the countryside. The land below is flat, dissected by river valleys that deepen as they reach further into their headwaters. And then, abruptly, the country changes from flat till plains to rolling hills and valleys; splashes of green forests and blue waters replacing the greys and blacks of pavement and rooftops. With a shift in perception through the lens of time, you can almost see the massive glacial rent in the ice sheet filling up with icy waters and a millennia worth of sand and gravel and boulders; these are the early days of the interlobate Oak Ridges Moraine, arcing like a huge eyebrow above the eye of Canada's largest city.

Image - map

Seen directly from above the first and most startling impression is "this is where the rivers begin!" All along the ridge of this regional surface water divide are many finger patterns of tiny headwater streams bubbling out of the ground in seeps and swales and springs. These trickles of water join forces, delivering cold clean water to the many rivers and streams that flow north and south from the moraine. The river valleys are well forested, providing living corridors along which animals travel. Wetlands and kettle lakes along the length of the watersheds are home to hundreds of species of birds and amphibians and provide needed watering holes for all kinds of wildlife.

Deep within the ground is the true treasure of the moraine - thick layers of sand and gravel many hundreds of metres from surface to bedrock. The waters in these aquifers span thousands of years in age; on the surface the water was yesterday's rain but deep deep down the water held in trust was once glacial ice. This is truly the lifeblood of the region, providing water to people, to rivers and to the oceans. It is these waters that may help us survive the warming of the years to come.

Image - roads

Strung along the rivers of the moraine are historic towns that show similar patterns of conurbation - the classic village center ringed by modern subdivisions and schools and baseball diamonds. Up or downstream are remains of dams signifying how important the fast flowing rivers once were to the economy of a century ago. Today, the millponds perform a different role of attracting birds and wildlife, bringing eco-tourist dollars to these struggling centers.

The second startling impression is the sight of a long and narrow urban band stretching from the south to the north straight through the hills and valleys. The Big Pipe decision decades ago helped to bury the precious tributaries under acres of pavement and to bring thousands of people up to the moraine. It was here where the moraine was almost cut in half by development and it was here where the battle for the moraine was staged and won. Through provincial intervention, this significant section of the moraine has been placed in the public trust, thus preserving a vital link in the regional natural heritage system.

Fields of corn, hay, soybean, horses and cattle seem to drape themselves around large garrulous old forests. Decades of restoration efforts to re-connect the forest fragments are evident in the thousands of acres of pine plantations, the hedgerow artifacts and the newly planted saplings put there by school children. It's obvious now that many of these marginal farm fields high on the ridge should never have been cleared back in the early days of First Contact - like long lost friends the newly-planted roots re-secure the fine sands and silts and hold them close. More productive farms on the north and south slopes are thriving and contribute strongly to the economy of the area - tractors move more slowly up and down the moraine hills than they do on the flat fields to the north and south. The natural curves of the rivers and forest edges are rudely pushed aside by the long linear slashes of roads first built to bring the Europeans to this land to conquer. Like ribbons of death, the new four lane highways do their best to stop the genetic movement of nature. But nature's resiliency proves too strong as plants and animals continue to move about the length of the moraine.

Yes, sprawl is nibbling at the southern front of the moraine and sprawl has been temporarily tamed. It will roar again in the future and its threat will never totally disappear. But for now development has been beaten back to the boardroom.

Debbe Crandall
STORM Coalition (Save the Oak Ridges Moraine) 

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Copyright 2007 Save the Oak Ridges Moraine (STORM) Coalition