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Lake Level to Keep Falling; Superior Has Dropped By 1 Foot in the Past Year

Posted on: Wednesday, 29 August 2007, 15:10 CDT

By DAN EGAN

Water officials from Canada and the U.S. said Tuesday that Lake Superior will probably continue its downward spiral in coming weeks to record low levels for late summer and fall, and they can do little about it.

This is a problem for more than just Lake Superior, because the water that tumbles out of the grandest of the Great Lakes and down the St. Marys River accounts for about 40% of the water supply for Lakes Michigan and Huron. Those two lakes are already about 2 feet below their long-term average levels and are within about 10 inches of their record low for late summer. Lakes Michigan and Huron are actually one body of water connected at the Straits of Mackinac.

Lake Superior, meanwhile, is almost at its record low for late summer, having lost about a foot of water in just the last year and about 2 feet over the last decade. Hydrologists blame lack of rain and increased evaporation for that stunning loss, which officials with the National Oceanic and Atmospheric Administration estimate is about 12.7 trillion gallons.

Lake Superior levels, which have been tracked since the 1800s, can be tweaked with changes in the way officials manage a complex system of locks, channels and hydropower generating facilities on the St. Marys River. But "there is really very little human influence on the system that can make any substantial change," said Scott Thieme, chief of the Army Corps of Engineers' Great Lakes office for hydraulics and hydrology.

That doesn't mean they aren't trying.

Flows on the St. Marys River have been throttled back to about two-thirds their normal for this time of year, from 83,300 cubic feet per second to 55,100 cubic feet per second. By comparison, the Chicago diversion on Lake Michigan averages about 3,200 cubic feet per second, which is equivalent to about 2.1 billion gallons per day.

Keeping all that water from leaving Lake Superior adds about 1 centimeter per month to the big lake. It also essentially takes away about three-quarters of a centimeter per month from Lakes Michigan and Huron, according to Rob Caldwell of Environment Canada.

Control a balancing act

Caldwell said Tuesday that federal water managers could further reduce flows into Lakes Michigan and Huron if things continue to get worse for Superior, but any such decision is guided by a set of rules between the two countries to essentially share the pain of low water levels among all three lakes. On the other hand, if things were to get worse in a relative way for Michigan and Huron compared with Superior, then Superior could be tapped for more flows.

"It's a balancing act," said Caldwell. "There is no one side that wins."

That doesn't mean there may not be hurt feelings. The Great Lakes states and provinces are attempting now to pass an agreement among themselves designed to protect the world's largest freshwater system from water grabs by thirsty outsiders. But if lake levels continue to shrink, squabbles over who should be getting how much could emerge between the Great Lakes states themselves, and even cities; what's good for shipping in Duluth may be bad news for shoreline property owners and anglers on Lake Michigan.

Still, water experts said all this tinkering amounts to mere drops compared with the gulps nature has taken from the lakes in the past few years. They said it will take a sustained pattern of above- average precipitation to return the lakes to their average levels.

Corps officials acknowledged not everyone buys their contention that nature is the biggest factor in the shrinking Lake Superior phenomenon, but they say the forces at play are almost too vast for many casual lake watchers to grasp.

"People think we have more control over Mother Nature than we do, or we should have more control," said the Army Corps' Thieme, referring to all the channeling and concrete on the St. Marys River at the outflow of Lake Superior. "There are these massive structures, and they seemingly look like we can do a lot with them. But you don't see precipitation and you don't see evaporation, basin- wide."

The bout of wet weather in southern Wisconsin last week, for example, had little impact on water levels in Lake Michigan. A big reason is the heavy rains didn't hit all across the Michigan and Huron basin, which stretches from eastern Wisconsin to Ontario.

"It's measurable, but not by very much - much less than a half inch, maybe a centimeter," said Cynthia Sellinger of the National Oceanic and Atmospheric Administration.

But both Canadian and U.S. water managers said Tuesday they are taking seriously the theory that more than weather is at play for the low levels on Lakes Michigan and Huron. A Canadian property owners group has funded an engineering study that charges an Army Corps dredging project in the 1960s has essentially pulled the plug on the St. Clair River, which is the outflow for the two lakes. That, the study claims, has led to the unexpected loss of more than 2 feet of water from the lakes' long-term average.

The U.S. and Canadian governments intend to look into the issue beginning later this year, and that study is expected to take about three years.

Copyright 2007, Journal Sentinel Inc. All rights reserved. (Note: This notice does not apply to those news items already copyrighted and received through wire services or other media.)

Source: Milwaukee Journal Sentinel

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