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_‘Trashed’ for 150 years, Toronto’s Don River struggles to run clean again_
Some see the Don River as an escape to nature in a highly urbanized environment. Others not so affectionately refer to it as an open sewer.
Experts were not surprised to hear that the Don, which flows into the heart of downtown Toronto, received a water quality rating of just 34.8 out of 100—among the lowest rated rivers in Canada and the worst in Ontario—in data released to the Citizen by Environment Canada.
“It has been industrialized and straitjacketed and pretty well trashed for the last 150 years,” said John Wilson, chair of Toronto’s Bring Back the Don committee.
“The blessing is that being right through the middle of the city, there are a lot of people using it for running and walking and biking,” said Mr. Wilson. “It is a little sliver of nature … yet at the same time it is not hard to miss that there are problems.”
The 38-kilometre long Don River starts in the Oak Ridges Moraine north of the city, winding through places such as Richmond Hill before emptying into Lake Ontario just east of downtown Toronto.
Calling the area “a highly urbanized watershed,” Adele Freeman, director of watershed management for Toronto and Region Conservation Authority (TRCA), said that about 85 per cent of the land that surrounds the river is developed.
Among the many issues that face the Don, Ms. Freeman said, the big three are clear: a large population, sewage overflow from older combined sewage systems and lack of forest cover or wetlands in an area where much of the ground is covered by impervious surfaces like paved roadways.
“Whatever washes off the street or from under your car … that becomes the quality of the Don River,” said Mr. Wilson.
“It is not that Toronto is dirtier than other cities in Canada,” said Tim Van Seters, manager of sustainable technologies at the TRCA, “but that the river is surrounded by a higher percentage of urban land.”
One of the biggest problems the Don faces at this time of year is chloride from road salt that washes off of nearby paved surfaces such as the Don Valley Parkway.
Chloride adversely affects sensitive species when it reaches roughly 240 milligrams per litre of water, said Mr. Van Seters. About 41 per cent of water samples taken between 2002 and 2005 exceeded that limit and the highest concentration the Don saw was 3,920 milligrams per litre. The median phosphorus levels were also reached five times the provincial recommendation.
“The Don’s diversity of fish is quite low because the biological and physical conditions that make up their habitat are very stressful,” said Christine Tu, supervisor for aquatic management at the TRCA.
There are up to seven species of fish in the Toronto area of the Don. The white sucker, fathead minnow and blacknose dace are among species that have adapted and become tolerant to things like low oxygen, said Ms. Tu.
“To say that there is no function or integrity is not accurate,” said Ms. Tu. “It’s just that we’re down to about as low as we would ever want to go in terms of diversity.”
Michael D’Andrea, director of Toronto’s water infrastructure management, said that the city has been working hard to curb the effects of the urban environment.
One initiative is a $1-billion, 25-year Wet Weather Flow Master Plan, which will control storm water and sewage overflow into the river through mandatory disconnection of roof spouts that send rainwater directly into older combined sewers.
Another multi-million dollar plan is the re-naturalization of the river.
“We’re looking at returning it to more of a natural environment with wetlands and natural parks,” said Elaine Baxter-Trahair, director of the waterfront revitalization initiative.
The plan’s environmental assessment is expected to be completed mid-2008 and the hope is that if enough resources are dedicated to the Don, it will be liberated from what Mr. Wilson calls its “concrete girdle.”
“It is a highly degraded water course and we all know that,” said Ms. Freeman. “But it is time that people stop looking at the Don as a sewer and start treating it as the centre of the city of Toronto.”
© The Ottawa Citizen 2007