Concern Rising Over Erosion From Manmade Lake in Preserve

by Staff -
(GEI)

By Russell Lissau, rlissau@@dailyherald.com

A man made lake at one of Lake County's most popular forest preserves has developed a natural problem: erosion.

Rising water levels and other factors have caused the 115-acre lake at Independence Grove Forest Preserve near Libertyville to damage some of its shoreline.

On the lake's western edge, water has overtaken what had been shoreline and carved out small sections of land. Elsewhere, a two- foot drop has replaced what once was a gradual slope leading to the water, forest board President Bonnie Thomson Carter said.

Fixing the problem could cost $600,000, forest district officials said. Because of the expense, the project will be spread out over two years.

The erosion will worsen if the forest district doesn't act, Carter said.

"It's not something we can just let go," she said. "Once shoreline starts eroding, it'll keep eroding farther and farther back. And then you have ... water quality issues."

Set on the northeast corner of Milwaukee Avenue and Route 137, Independence Grove opened to the public in 2001. Before its purchase by the forest district in 1978, the site was a gravel pit.

Mining was allowed to continue into the 1990s to fund the eventual improvements at the site.

Erosion was a concern when the lake - the forest district's largest - was created. To prevent shoreline damage, crews built underwater shelves along what had been the quarry edge and planted wetland plants on those shelves to slow wave action.

A pump was installed to control the water level, too. That pump broke last year, however, allowing the lake level to rise.

At one point, the water was 18 to 20 inches deeper than normal, said Mike Fenelon, the district's planning, conservation and development director.

"It was a significant amount," Fenelon said.

Weather conditions this past winter worsened the erosion, officials said. Particularly harmful was the ice that formed on the lake and what had been the shore. The ice further damaged the land when it broke up, Carter said.

"Ice is really tough on a shoreline, whether (the shore) is natural or man made," she said.

To fix the problem, crews will re-grade and re-seed the edge of the lake, Fenelon said. They'll also use stones to reinforce shoreline areas that suffered extreme erosion.

Additionally, officials will lower the water level in the lake by about a foot after Labor Day, Fenelon said.

Erosion has affected the lake before. A much smaller section of shoreline was damaged by erosion about six years ago, he said.

(c) 2008 Daily Herald; Arlington Heights, Ill.. Provided by ProQuest LLC. All rights Reserved.

Source: Daily Herald; Arlington Heights, Ill.

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