Record snowpack should replenish low levels in Great Lakes
By Tom Spears
CanWest News Service
Published March 10, 2008
OTTAWA - This winter's heavy snowpack is excellent news for water levels in the Great Lakes and St. Lawrence River, and should also replenish groundwater for farmland and inland communities.
Falling water levels have caused problems for shipping through Montreal Harbour, and for shoreline residents along Lake Huron, Georgian Bay and other parts of the world's largest lake system.
The Great Lakes get a lot of their water from melting snow. And for many years, snow has been scarce compared with historic norms.
This year the region has had waves of heavy moisture from the southern U.S. states and Gulf of Mexico. This helps more than "lake effect" snow which justs recycles the lakes' own water.
"The problem is we haven't had anywhere near this kind of winter conditions for quite a while, and the levels have dropped and dropped," said Ottawa's Jim Bruce. He's a former senior official with Environment Canada and now sits on a panel advising the International Joint Commission, the Canada-U.S. body overseeing the Great Lakes.
"How much (more water) we'll get is impossible to say, but it's going in the right direction. And groundwater levels, in places where they're down, will also come back up with the snowmelt."
Recent winters have seen pockets of heavy snow here and there, but this year has dumped near-record amount throughout the Great Lakes basin. That includes Great Lakes states such as Wisconsin, Michigan and Illinois.
The U.S. Army Corps of Engineers is also forecasting rising water levels throughout the lakes.
But Bruce says conditions in the late winter and early spring will determine how much of the meltwater actually goes into the lakes.
"It depends a lot on how the snow goes (melts)," he said. "If it melts slowly and there's warm sun, you can lose a lot of water from the snowpack through sublimation."
This is a process where snow crystals turn directly to water vapour instead of melting.
Higher water levels are badly needed in Montreal, he noted. "Montreal Harbour has been rather badly hit. This (extra snow) should help their situation."
Monthly measurements from the Canadian Hydrographic Service, part of Fisheries and Oceans Canada, show Montreal Harbour had record low water levels in the fall. But the levels have risen sharply this winter and are now approaching average. Records there date from 1967.
Lakes Erie and Ontario are close to average. But Lake Superior hit record low levels last fall, and Lake Huron and Georgian Bay had fallen close to a record low in late fall, 70 centimetres below the average dating from 1918. Shoreline residents and cottagers have had to build steps down from their docks in recent years to reach the water.
Lake freighters have had trouble at many harbours, and have had to carry less cargo to float higher in the water.
This winter, however, water levels throughout the lakes, there have risen at a time of year when they normally fall, and projections show more improvement is likely in the next few months.