Water levels in the Great Lakes are falling; Lake Ontario, for example, is about seven inches below where it was a year ago. And for every inch of water that the lakes lose, the ships that ferry bulk materials across them must lighten their loads by 270 tons — or 540,000 pounds — or risk running aground, according to the Lake Carriers' Association, a trade group for United States-flag cargo companies.
As a result, more ships are needed, adding millions of dollars to shipping companies' operating costs, experts in maritime commerce estimate.
"When a ship leaves a dock, and it's not filled to capacity, it's the same as a plane leaving an airport with empty seats: It cuts into their earning capacity," said Richard D. Stewart, a co-director of the Transportation and Logistics Research Center at the University of Wisconsin-Superior.
"Because it's mostly raw materials we're talking about, the average consumer may see an increase in pennies in the price they pay for, say, a new car or washing machine," Dr. Stewart said. For major manufacturers or firms managing big projects, however, the increase in transportation costs "is much more significant," he said.
The water levels in all five Great Lakes — Superior, Michigan, Huron, Erie and Ontario — are below long-term averages and are likely to stay that way until at least March, according to the Army Corps of Engineers. (The same is true at Lake St. Clair, which straddles the border between the state of Michigan and the province of Ontario and is between Lake Huron and Lake Erie; it is not considered one of the Great Lakes, although it is part of the Great Lakes system.)
The International Joint Commission, which advises the United States and Canada on water resources, is conducting a $17 million, five-year study to determine whether the shrinking of the Great Lakes is related to the seasonal rise-and-fall cycles or is a result of climate change, said Greg McGillis, a spokesman for the commission. A final report is expected in March 2012.
Lake Ontario stood at 244.1 feet as of Wednesday — 3 inches below where it was at the beginning of the month, 5 inches below last month's average and about a foot below last year's average. The water, however, is still about 2 feet above the lake's low of 242.19 feet, registered in 1934, according to the Corps of Engineers.