Lake Superior continues downward slide
- Lake Superior continues downward slide
By John Myers
Published in the River Falls Journal January 5, 2007
The world's largest freshwater lake keeps getting smaller, inch by
inch, as the worst drought in at least 30 years grips the Northland.
The International Lake Superior Board of Control reported Wednesday
that Lake Superior continued its decline through December and sits at
its lowest Jan. 1 level in 81 years.
The lake dropped two inches in December. It now sits a foot below the
level it was at this time last year and more than 18 inches below the
average for the month.
So far, contrary to some media reports, the big lake's big drop
hasn't set any monthly or all-time records. As low as it is now, Lake
Superior is still three inches above its all-time January low and 10
inches higher than the all-time record low set in April 1926.
Even with the lake expected to drop through March, it's unlikely to
fall below the 1926 record, said Cynthia Sellinger, a National
Oceanic and Atmospheric Administration scientist at the Great Lakes
Environmental Research Laboratory in Ann Arbor, Mich.
"At this point, I don't see that happening," she said. "But that
could change if it stays dry."
Precipitation across the Lake Superior basin was only about 60
percent of normal in December, although that's closer to normal than
recent months. There has been less evaporation because of fewer cold
snaps, which pull moisture from the lake.
"The lake actually declined a little less than normal in December.
But not much less," said Carl Woodruff, a hydraulic engineer for the
U.S. Army Corps of Engineers Detroit District.
Lake Superior is so huge that the decline has been hard to notice to
the untrained eye. Even at 18 inches below the long-term average, the
lake doesn't look much different to most people.
Park Point residents are noticing a wider-than-ever beach. And Great
Lakes freighters are traveling with less-than-full loads because
water levels in harbors are so low. That means thousands of dollars
more to move the same amount of coal, taconite and grain millions
of dollars spread across the hundreds of vessels on the lakes.
Environmentally, low water levels shouldn't have much effect on Lake
Superior, and may even help prevent erosion along sensitive
shoreline. But the drought has affected the lake's tributary streams,
where some salmon and trout spawn. North and South Shore streams are
running at near-historic low seasonal levels, as are most rivers in
While heavy rain last weekend will help soften the drought, it's far
from over. The National Drought Mitigation Center is forecasting the
region's extreme drought to continue through March before any relief
Some northern Minnesota areas had their lowest rainfall levels in
recorded history during the past growing season, from May to October.
So far this year, snow-depth rankings have been off the charts the
sparsest December snow cover ever in some places.
"If the next 90-day forecast is the same as the current one, then
we'll see a continued decline in the lake's level," Sellinger
said. "You've got very little snowpack. The levels already are low.
And if there's not the usual spring rains, that's not a good
combination. At this point, I'm not seeing much of a spring runoff
increase (in water levels) like we would normally get."
With a warmer and dryer than normal Northland winter forecast through
March, the prognosis for relief isn't great. Evaporation across the
lake's 31,700-square-mile surface area will continue to suck water
out of the lake, especially with little or no ice cover thanks to
unusually warm weather. Woodruff said occasional blasts of cold air
across the unfrozen lake will pull even more moisture out of Lake
Superior and deposit it on land as lake-effect snow. Much of that
moisture returns to the lake, but there's no net gain.
"What we need are some big storms to come in from the west to bring
in new moisture," Woodruff said. "Since early summer, Lake Superior
has been just starved of moisture."
A new study by the International Joint Commission will try to
determine whether the decline is part of a larger pattern. The report
will look at the impact of weather cycles, climate change and how the
lake's outlet at Saulte Ste. Marie is controlled. That outlet
determines how much water can be used for hydroelectric power
generation and how much moves into the lower lakes.
The study also will look at whether a dredging project on the St.
Clair River in 1962, which allowed more water to leave lakes Huron
and Michigan, has contributed to low water levels. When the river was
dredged to 30 feet deep allow heavier ships to pass, erosion scoured
parts of the river to more than 60 feet deep. Some say that has
opened a wider funnel out of the upper lakes. But because the lake's
record high came in the 1980s, after the dredging, skeptics say
climate variations not dredging are the primary factor in Lake
Superior water levels.
Others say a contributing factor could be the ongoing settling of the
earth below the Great Lakes, still changing after the last glacial
period and tilting more water out of the basin.