Snow, cold: Silver lining for shipping
MADISON — There is a silver lining to the severe winter for shippers as snow and cold temperatures have reversed decades-long declining levels on Lake Superior and the other Great Lakes, according to U.S. Army Corps of Engineer forecasters.
Lake Superior is showing the biggest recovery as the ACE reports the level is a foot higher than last year at this time but an inch below its long-term average.
“The cold temperatures, seemingly endless snowfalls and near-record setting ice cover,” have helped stem a decades-long lowering of lake levels, Keith Kompoltowicz, a meteorologist in the ACE’s Detroit office said Wednesday.
Lake Superior’s level is forecast to remain an inch or two above last year’s level into August.
Snowfall across the Great Lakes basin is 30 percent above any year in the past decade, and ice coverage for all the lakes was 93.1 percent Tuesday, the second highest total since 1977, said Kompoltowicz.
That not only increases the potential water supply to the lakes but also slows evaporation during the cold weather months, he noted.
The snow pack around Lake Superior holds an estimated 9.5 inches of water equivalent, which also is well above the annual average.
Higher lake levels will help shippers as each inch of water depth allows a typical 1,000-foot-long ship to carry an additional 240 tons of cargo, said Richard Stewart, a transportation researcher at the University of Wisconsin-Superior.
“Every inch is of consequence for cargo carrying vessels as they can carry more per trip … which can result in fewer trips,” during a shipping season, he said.
The Great Lakes form a shipping system and carriers can only load as much will float over the shallowest depth along the route, Stewart said.
There is good news for down bound shippers as levels in lakes Michigan and Huron are 8 to 14 inches above last year and may remain several inches above their long term average through August, Kompoltowicz said.
Just last year lakes Michigan and Huron reached some of their lowest levels since 1918 and have been low for since the 1990s, he said.
Lake St. Clair, lying between lakes Huron and Erie is three inches above last year but seven inches below its long-term average. Ice formations on the St. Claire River has been restricting Huron’s outflow into Erie, said Kompoltowicz.
Lake Erie currently is three inches above last but two inches below its long-term average and is expected to fall slightly below its long-term average by July or August, he said.
Lake Ontario is four inches above last year and near its long-term average level.
The Soo Locks connecting Superior and Huron are scheduled to open March 25, according to the ACE’s Maj. James Booth. Navigation for at least the short-term may be limited to the amount of shipping lanes the Coast Guard can keep open then, Booth said.
“They’re expecting a difficult go of it when navigation resumes,” he said.
Ice coverage began forming earlier this winter than any in the past 40 years and is expected to linger longer than normal as well, said George Leshkevich, an ice expert with the Great Lakes Environmental research Laboratory.
Extensive ice cover benefits commercial fishermen as whitefish require stable ice cover to protect spawning beds and increase propagation, he said.
“Lake Superior being a foot higher than last year is great news and even better is the higher levels in lakes Huron and Michigan and the St. Claire River, said Adele Yorde, spokesperson for the Duluth Seaway Port Authority.