TRAVERSE CITY (AP) – A U.S.-Canadian advisory panel wound up a five-year study this week with a recommendation against large-scale engineering projects to prevent swings in Great Lakes water levels, saying people across the region should adapt to nature’s ups and downs.

The $14.6 million investigation concluded that trying to control levels by placing more structures at choke points such as the St. Clair River at the south end of Lake Huron would be too expensive and damage the environment. About 200 scientists and engineers contributed to a report requested by the International Joint Commission, which advises both governments on issues affecting the Great Lakes and other boundary waters.

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“It’s a reality check,” said Ted Yuzyk, Canadian co-chairman of the International Upper Great Lakes Study Board. The report discourages people from “hoping the government will miraculously step in and solve the problem,” he said.

The findings were sure to disappoint many along Lake Huron’s Georgian Bay, where levels have been abnormally low since the late 1990s. The drop-off has hurt marinas and other businesses, forced shoreline residents to relocate docks and boathouses, and dried up ecologically valuable wetlands.

A group representing property owners along the bay, the Great Lakes’ largest, wants measures to compensate for excessive water losses caused by dredging and sand mining in the St. Clair River in the 1960s and earlier. They could include using structures such as underwater “speed bumps” or inflatable gates to slow the outflow from Lake Huron south toward Lake Erie.

“A responsible plan must and can be found to restore the water levels” to where they were before humans intervened, said Mary Muter, a Georgian Bay resident and representative of Sierra Club Ontario.

Study leaders acknowledge something triggered faster outflows but disagree with the Georgian Bay group over how much water has been lost. Yuzuk said the flow rate returned to normal around 2000.

The report found the structures could cost up to $170 million and disrupt fish habitats, including spawning areas for rare Great Lakes sturgeon. Many homeowners along southern Lake Michigan also oppose raising levels on Lake Huron, which is connected to Lake Michigan by a 5-mile-wide straits area. They fear a return of high water that eroded beaches and swept away cottages in the mid-1980s.

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The study group also dismissed the idea of trying to control the levels of all five Great Lakes with massive dam construction, saying it would cost billions and take decades to complete. Even then, it’s questionable whether manmade infrastructure could trump the influence of rainfall, evaporation and runoff, the report said.

John Jackson, of the U.S.-Canadian environmental group Great Lakes United, praised the recommendation to avoid big-ticket engineering projects but said authorities should investigate other ways to raise Lake Huron levels, such as removing seawalls that prevent a buildup of sand on the St. Clair river bottom.

Adjusting releases from Lake Superior, which already are controlled by gates and hydropower turbines on the St. Marys River, would produce a more natural and stable flow to the other lakes, the report said. It also would provide more flexibility to deal with wetter or drier conditions that could result from climate change, which the report said might not alter levels as dramatically as previous studies have suggested.

The report called for a board to oversee studies of why the lakes rise and fall. That could help people anticipate changes and adjust in ways such as building dikes to hold water in wetlands, Yuzyk said.

But it’s unclear whether wetlands that developed over thousands of years can adapt, said Patricia Chow-Fraser, a biologist with McMaster University in Ontario.

“We cannot allow these sustained low water level conditions to continue,” she said.

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