Saturday, March 12, 2005

Adam Bird / Associated Press Cheryl Mendoza stands in front of Lake Michigan near her home in Grand Haven. Mendoza has been carefully watching the water level of the lake, which is starting to return to its normal level after being low for some time.

Wetlands, fish, people benefit from rise in Great Lakes' levels

By James Prichard / Associated Press

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GRAND RAPIDS -- Rising water levels in the Great Lakes during the past year not only have delighted property owners, who prefer views of waves over weeds, but the swelling bodies also are feeding commerce and a variety of plants and animals that call the lakes home.

High water means more cargo and bigger profits for the shipping industry. It means boaters can more easily get into and out of marinas. It means more visitors at Michigan's beaches.

It also means the replenishment of wetlands along the state's shoreline, which are havens for countless varieties of fauna and flora.

Many people expressed concern about the drop in the Great Lakes' water levels that occurred from the late 1990s through last year. Lakefront property owners disliked seeing the exposed weedy bottomlands that are crucial to wildlife. Less water meant less cash for shippers in an industry where an extra inch of lake water allows a 1,000-foot freighter to carry an additional 270 tons of goods, according to the Cleveland-based Lake Carriers' Association.

Douglas Wilcox, who heads up the coastal and wetland ecology branch of the U.S. Geological Survey's Great Lakes Science Center in Ann Arbor, said many people don't understand the cyclical rise and fall of the lake levels or their long-standing importance to the well-being of the lakes' complex ecosystem.

"The absolute best thing that could happen is to have a high lake level followed by a low lake level, and then water levels come back up," he said.

"The low lake levels that we had several years ago were a godsend. We've been waiting since the 1960s to have low lake levels. They expose the sediments."

Many wetlands dot the state's shoreline, particularly in bays, inlets and river mouths, and taller, broader plants can dominate a wetland in which the water level is high.

As the water recedes and the lake bottom is exposed, the dominant plants will die off and other species whose seeds may have sat dormant for years in the sediment will replace them, regenerating plant diversity.

Without that process, such a habitat would be lost, Wilcox said.

"Those plant species will provide food and habitat for incredible numbers and diversities of invertebrates, which will provide food for a whole lot of small fish, which will provide food for a whole lot of big fish," he said.

When water levels drop and lake bottoms are exposed along the shoreline, the resulting mud or sand flats often become covered with vegetation. While owners of beach homes might consider the plants weeds in need of removal, waterfowl love the vegetation, said Wil Cwikiel, policy director of the Tip of the Mitt Watershed Council in Petoskey.

"It's great for nesting mallards," he said. "They love to nest in that sort of thing."

As a lake rises, its vegetative coastal areas and wetlands become ideal spawning grounds for many fish species, including bass, perch, muskie and walleye. When the water levels off, wave action and ice formations remove much of the underwater vegetation, necessitating the need for another drop.

Cynthia Sellinger, a hydrologist at the Ann Arbor-based Great Lakes Environmental Research Laboratory operated by the National Oceanic and Atmospheric Administration, said the levels of all five Great Lakes are much higher than they were in March 2004.

As of this week, Lake Erie was up 16 inches, Lakes Huron and Michigan were 11 inches higher and Lakes Ontario and Superior were up 8 inches.

Sellinger blamed the below-normal levels of the previous half-dozen years on less rain and snow in the Great Lakes basin combined with more evaporation caused by unusually warm temperatures.

The basin includes the Canadian province of Ontario and portions of eight states: Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania and Wisconsin.

"Last fall was a very wet fall and that just really started pushing the lakes back up," Sellinger said. "Then this winter has been really good because we've had a cold winter where we're having a nice snow pack building up, so by the time the ground thaws, we'll have a good spring runoff."

Good enough for water levels to remain above last year's amounts for at least another six months, she said. "I know boaters are really excited about that."

The levels of Lakes Erie, Ontario and Superior are between 3 and 11 inches higher than their long-term averages measured between 1900 and 2000, she said.

Lakes Michigan and Huron, which are always at the same water level because of their hydraulic connection at the Straits of Mackinac, are 9 inches below their long-term averages. It might be because of different weather patterns on those two lakes, Sellinger said.

"The region's so large, we don't get just one air mass," she said.

While weather patterns, ocean currents and even sun spots affect lake levels, some environmentalists worry about human influences such as global warming and dredging in the Great Lakes' connecting channels.

"The greater concern was, is this a natural fluctuation that's going to come back or is this some permanent damage that's being caused from climate change," said Cheryl Mendoza, water-conservation program manager of the Lake Michigan Federation, which has offices in Chicago and Grand Haven.

"The Great Lakes are fragile and they are vulnerable, and we need to better understand the role that humans can play in manipulating and changing and altering that natural cycle," said Tip of the Mitt's Cwikiel.

On the Net:

Great Lakes Science Center: http://www.glsc.usgs.gov/

Tip of the Mitt Watershed Council: http://www.watershedcouncil.org/

Great Lakes Environmental Research Laboratory: http://www.glerl.noaa.gov/

Lake Michigan Federation: http://www.lakemichigan.org/