The largest discharges came from big cities such as Detroit, Cleveland and Toronto, where antiquated sewage treatment systems are regularly overwhelmed when it rains and their contents swept untreated into the lakes. But even smaller communities, such as Ontario's London and Kingston, release large quantities of raw sewage.

Information on the discharges was compiled by the Sierra Legal Defence Fund, based mainly on estimates the environmental group obtained from the municipalities themselves. According to city figures, sewage dumping occurs hundreds of times a year, releasing a cocktail of human waste, disease-causing organisms and hundreds of synthetic chemicals from drugs and personal care products.

The total volume of untreated waste at the 20 cities from which the group obtained information was about 98 billion litres a year, enough to fill 37,000 Olympic-size swimming pools with sewage. This volume likely underestimates the magnitude of the pollution problem because it is based on cities representing only about a third of the region's 35 million residents.

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GIMME SMELTER

The sewage figures are being released today in a report whose author said she was shocked by the volume of wastewater that escapes treatment, a wave of sewage that is behind frequent beach closures around the Great Lakes and the reason why drinking water from the lakes needs such extensive treatment to make it potable.

"It's appalling. I think countries as wealthy as Canada and the U.S. can do a hell of a lot better in terms of managing their sewage. The fact that we live on the shores of 20 per cent of the world's supply of fresh water and we treat it this way, there is just no excuse for it," said Dr. Elaine MacDonald, the author and a staff scientist with the group.

Sierra Legal began studying the fate of Great Lakes sewage after conducting similar studies on cities along Canada's coasts, where it found major centres, including Victoria and Halifax, dumping waste water into the ocean with little or no treatment.

Although sewage treatment is more extensive along the five Great Lakes, where governments have been fighting water pollution for more than three decades, the group was unable to find any municipality with what it considered a fully up-to-date wastewater treatment system. Green Bay, Wisc., and Ontario's Peel Region came closest.

The cities it considered to have the most antiquated systems were Detroit, Cleveland and Windsor, Ont. Toronto was ranked in the middle of the group.

According to the report, the biggest factor leading to pollution problems is municipal use of the same network of pipes to carry both sewage and storm water runoff from streets and roofs.

These pipes, built cheaply decades ago, are found in varying numbers in almost all older urban areas along the Great Lakes.

Combined storm and sanitary sewers aren't big enough to handle both sewage and rainwater flows whenever there is precipitation, so cities divert the contents of these pipes into the lakes during storms to prevent sewage from backing up into homes.

In Detroit, all sewer pipes in older parts of city also carry storm water, and an estimated 5 per cent of wastewater is dumped untreated into Lake Erie tributaries when there is precipitation. The city had the largest flow of raw sewage entering the Great Lakes of any community. "Detroit is quite a quagmire," Dr. MacDonald said.

A spokesman for the city defended its wastewater treatment system, saying it has spent about $1-billion over the past 10 years on cleanup efforts.

George Ellenwood said wildlife is returning to Detroit's waterfront area, indicating strides in its efforts at pollution abatement.

He said it was impractical and too costly for the city to separate combined storm and sanitary sewer system.

In Windsor, the worst-ranked Canadian community, a city official said it expects to complete an overhaul of one of its wastewater treatment plants early next year.

Dr. MacDonald said raw sewage discharges from Canadian cities likely violate the federal Fisheries Act, which makes it illegal to discharge wastewater dangerous to fish.

A number of cities refused to reveal their pollution figures or provided incomplete information. This group included York Region, Kitchener-Waterloo and Buffalo.

Slipping on sewage

Many cities dump untreated sewage into the lakes when it rains because they have antiquated pipes that also carry rainwater, overwhelming their treatment systems.

Combined sewer outflows into the Great Lakes

The cities are ranked according to their discharges of raw sewage into the Great Lakes. The larger the circle around a city, the greater its discharge volume.

City Annual discharge in millions of litres per annum -- Percentage of untreated sewage released annually

Detroit----------- *50,000 ----------- 0%

Cleveland---------- 20,820 ------------ 0%

Toronto------------ 9,000 ------------- 0%

Milwaukee---------- 4,110 ------------- 5.30%

Syracuse----------- 2,645 ------------- 5.77%

Hamilton----------- 2,109 ------------- 2.14%

Windsor------------ 1,809 ------------- 1.49%

Niagara------------ 400---------------- 2.27%

Rochester---------- 379-----------------1.70%

Kingston----------- 349---------------- 2.68%

Sudbury------------ 317---------------- 1.00%

London------------- 300---------------- 0.25%

Erie--------------- 190---------------- 0.95%

Grand Rapids------- 190---------------- 0.99%

Duluth-------------- 38---------------- 0.40%

Sault Ste. Marie----- 8---------------- 0.35%

Peel---------------- 5---------------- 0.29%**

Thunder Bay---------- 0---------------- 0.07%

Green Bay------------ 0--------------- 0.05%

* Estimate ** 0.29 (0.06 raw plus 0.23 partial)