A month of temperatures below minus 4 Fahrenheit has caused an ice blanket averaging as much as 24 inches on the lakes,
creating problems for shipping companies and ferries.
"The large lakes freeze once every decade," said John Falkingham, chief of forecast operations, at the Canadian Ice Service,
which is part of Environment Canada. "A sustained long, cold spell causes such an extensive ice cover."
The three lakes are part of the five Great Lakes, including Lake Michigan and Lake Ontario, which constitute the largest
fresh water system in the world and represent 18 percent of global fresh water supply and 95 percent of the U.S. supply, according
to the Great Lakes Information Web site (www.great-lakes.net).
Lake Superior, the largest of the five, is more than 32,000 square miles -- or almost the size of Austria.
Canadian Ice Service said satellite images showed that Superior and Huron froze over for the first time this year on Feb.
27, after record low temperatures, without a hint of the warming trend that is normal for this time of year.
That frigid weather continued into March. Last week, the temperature fell below minus 13 Fahrenheit in southern Ontario,
the coldest for March in a century, according to Environment Canada.
The cold weather has affected the St. Lawrence Seaway, which will now open on March 31, almost a week behind schedule,
said Ivan Lantz, director of marine operations for the Shipping Federation of Canada, an organization of shipowners and agents
involved in the overseas trade.
"My estimate is that before the 15th of April, shipping is going to be very difficult," Lantz said.
On Canada's east coast, ferry service between Sydney, Nova Scotia, and Port aux Basques, Newfoundland, has also experienced
difficulty because of ice. A ferry spent part of Sunday caught in ice and had to be helped by an icebreaker.
Falkingham said the ice is expected to thaw by the end of April.
