Many Ontario and American cities are failing in efforts to keep untreated urban sewage and effluent from flowing into the Great Lakes each year, suggests a study released Wednesday by a Canadian environmental group.

The resulting pollution is threatening one of the world's most important freshwater ecosystems, says the Sierra Legal Defence Fund.

Elaine MacDonald, the author of the study, told CBC Newsworld the pollution affects biodiversity, water-treatment costs and our ability to enjoy the water.

"We can't go swimming in the summer at our beaches, that's a direct effect," said MacDonald, citing the effect of sewage overflows following rainstorms.

Sierra Legal graded the performance of 20 Ontario and U.S. cities and municipalities on how they managed their sewage, and called the results appalling.

Windsor had the worst record among the 10 Ontario cities or municipalities in the study, with only Detroit and Cleveland scoring a lower performance record for treating sewage.

Sudbury, Kingston, Hamilton, Sarnia, Toronto and the Niagara Region also received below-average grades.

Peel Region, which includes Mississauga, Brampton and Caledon, was the highest-ranked Ontario municipality, largely because of its ability to keep rain water and sewage separate, the study says. The region trailed only Green Bay, Wis., in the rankings.

Thunder Bay, London and Sault Ste. Marie also were in the top 10. Two other urban areas in Ontario — Kitchener-Waterloo Region, and York and Durham regions —were unranked after refusing to respond to the survey.

Particularly troubling was the inconsistency between Ontario's urban regions, said MacDonald.

"There were three cities on the Canadian side which only had primary treatment, while on the American side they all had secondary systems," she said.

"We don't even have standards in the province of Ontario," she said. "We have rules and regulations, but no standards. We need national standards."

Every Canadian city except Toronto scored an A for avoiding commercial raw sewage discharges from spills or plant bypasses, the study says.

But Toronto also had the most comprehensive effluent test of all 20 cities, conducting over 6,600 tests per year.

Sewage treatment grades and ranks for Canadian municipalities (Source: Sierra Legal Defence Fund)
City or Municipality	Grade	Rank
Peel Region	B	2nd
Thunder Bay	B-	4th
London	C+	7th
Sault Ste. Marie	C+	10th
Niagara Region	C+	11th
Toronto	C	12th
Hamilton	C	Tied- 13th
Sarnia	C	Tied-13th
Kingston	C	15th
Sudbury	C	16th
Windsor	D+	18th

The main culprit for poor grades for Canadian cities was the frequency of sewer overflows. Antiquated sewage systems incapable of dealing with the vast amounts of effluent flowing through them were the main problem, the study said.

The overflow results in some 91 billion litres (24 billion gallons) of untreated effluent enter the Great Lakes every year, the study found.

Sudbury and Hamilton were also singled out for poor municipal planning, with both regions scoring D marks for future plans and updated sewer-use bylaws.

The report made several recommendations, including:

• Improving water conservation to reduce the flow to sewage plants.
• Keeping rainwater out of sewers by separating storm drains and sewer systems.
• Upgrading sewage-treatment plants to remove toxic substances from entering the lakes.

"If we want future generations to be able to enjoy this vibrant ecosystem and all it offers," the report concludes, "we need to change our ways and stop treating the Great Lakes like a toilet."