Mild winter exposes Lake Michigan to risk of low levels
In normal winter, ice cover slows evaporation, snow tops
By MEG JONES
Milwaukee Journal Sentinel
Last Updated: Jan. 10, 2002
As sand bars grow, docks get higher and Lake Michigan
continues to shrink, a much-needed water boost that normally
happens each winter isn't materializing.
So far, there's not much snow to melt in the spring and
run into the Great Lakes. In addition, higher than normal
temperatures mean little or no ice forming across lakes
to prevent evaporation, experts said.
Relatively benign weather since the last El Nino of 1997-'98
has dropped water levels in the Great Lakes to some of
the lowest in decades. Last year, Lake Michigan was the
lowest in 35 years, authorities said.
Thanks to this winter's unseasonably balmy weather, Lake
Michigan's water is now evaporating faster than normal.
Usually by this time of year, 60% to 70% of Lake Michigan
is covered in ice, but "this winter there's hardly
any ice cover on Lake Michigan at all," said Roger
Gauthier, a U.S. Army Corps of Engineers hydrologist based
"That's not a good sign. That's a sign that lake
levels will be under pressure again," Gauthier said.
Lakes always evaporate in the winter as cold wind blows
over warmer water. As ice forms the evaporation slows.
But not this year.
In Lakes Michigan and Huron, which are the same height
because they're connected by the Straits of Mackinac,
the water level has dropped by more than 40 inches since
1997 and remains 13 inches below average. Lake Superior
is 3 inches below average, and Lake Erie is 4 inches below
normal, while Lake Ontario is at its average level.
With lower water levels, shipping companies can't fill
their ore carriers as full for fear of running aground.
Ships traversing Lakes Superior and Michigan are hauling
an average of 64,000 tons, down from 70,000 tons in the
mid-'90s before the Great Lakes began dissipating. Last
year was worse, with ships forced to load only 60,000
tons of coal, iron ore, cement and other commodities,
said Glen Nekvasil, vice president of corporate communications
for the Lake Carriers
"When we leave 10,000 tons of iron ore or coal on
the dock, we leave behind $350,000 worth of cargo,"
"What it really means (is) when we're leaving cargo
behind, a ship has to make more trips to deliver the same
amount of cargo."
Larry Sullivan, chief engineer for the Port of Milwaukee,
noticed ships coming in lighter than usual last year.
Dredging was done at the Milwaukee port in 2001, but the
project had been planned for a long time and wasn't related
to low water levels, Sullivan said.
As the Great Lakes drop, docks get higher, sandbars get
bigger and some boat ramps become inaccessible. When water
levels are lower, waves act differently, which can be
hazardous to boaters.
"Every spring when we get storms, we get breaking
wave conditions where we aren't used to seeing them,"
said Philip Keillor, coastal engineering specialist with
the Sea Grant Institute in Madison.
"Last spring a fishing tug almost got rolled over
going into Two Rivers. That's a problem for shallower
harbors like Two Rivers but also deep harbors like Superior,
where in late November they had a storm with waves 20
feet high," Keillor said.
Keillor said receding water is also rapidly aging harbors
that were built a century ago. The wooden structures are
exposed to the air in many spots, which means they're
rotting faster, Keillor said.
A shallower Lake Michigan isn't all bad, though. There
are more beaches. Shores aren't eroding, and some of the
areas formerly under water are now wetlands, which offer
plenty of food and habitat for a variety of wildlife species.
"We definitely have more biodiversity on our shores
since 1997," Gauthier said.