A study finds almost 2/3 of bacteria comes from livestock waste.
This is the first report to show how much bacterial pollution comes from different sources between Goderich and Kincardine.
Agriculture waste is a major factor contributing to pollution in lake Huron according to a recent University of Guelph study.
Livestock accounted for between 59 and 62 per cent of E. coli entering the lake.
The rest came from wildlife, human waste and unknown sources.
Human sewage accounted for one to three per cent, according to Professor Jack Trevors.
He co-authored the study with U of G environmental biologist Prof. Hung Lee and researchers from the Ontario Ministry of the Environment.
Their research paper appeared in the March issue of the Canadian Journal of Microbiology.
"We know agriculture is important to Ontario," said Trevors. "We're using scientific tools to learn about the environment and how to sustain and improve our water resources."
The team compiled DNA samples from potential E. coli sources and compared those against samples taken in 2005 and 2006 from Lake Huron and the creeks and rivers feeding it.
Alberta's chief veterinary officer says 500 pigs were slaughtered on a quarantined farm where swine flu was detected last week.
But Dr. Gerald Hauer says it has nothing to do with food safety.
He says the decision to cull the animals was to ease overcrowding on the central Alberta farm.
The herd of 17-hundred pigs remains under quarantine, the population is growing and space is limited.
Agriculture officials say there's no solid proof that pigs on that particular farm ever contracted the virus from a farm worker.
The Canadian Cattlemen's Association says a potential trade deal with the European Union could transform the industry.
President Brad Wildeman says a free trade deal with the E-U could diversify the market and knock down major barriers to Canadian beef.
Canada has virtually no commercially-viable access to the European market.
However, he cautions the talks could take a year or more to negotiate.
The E-U consumes over 8 million tonnes of beef a year and the association says the market could rival the U-S.