A dam made of interlocking steel sheet pilings on the Des Plaines River near Ryerson Woods Forest Preserve in Riverwoods is coming down this week, replaced by boulders and rock as part of river restoration efforts.

The effort involves using a 7-foot-tall portable dam to divert half of the river while crews from Clear Cut Tree Services of Grayslake dug out the failing steel wall that was a hazard to canoeists and kayakers.

The old dam also trapped silt and eroded banks not far from the Ryerson log cabin. The Ryerson family built the dam in the late 1920s-early '30s so farm equipment could be moved across the river. During the popular Des Plaines River Canoe Marathon, the second-oldest canoe race in the United States, racers were required to portage around it because of the danger of injury.

"It will be a nicer stream (for them)," said Jim Anderson, natural resource manager for the Lake County Forest Preserve District.

Andy Cocallas, a Libertyville resident and owner of Max's Dawg House in the village, is a longtime canoeist and marathoner. He said the dam had caused a lot of erosion problems and was considered dangerous. Canoe racers were required to portage around the dam.

"I'm very excited," he said, adding that he has already talked with race officials about eliminating the portage. "I already paddled over it. It was easy, it was real nice. There is a nice chute to paddle through," he said, unless the water is very low.

"It was pretty cool how they did that," he said, referring to the Portadam that diverted half the river and the pumping operations to keep it just dry enough to dig and cut the steel off about two feet below the stream bed. The second half of the dam is being removed this week.

In place of the dam will be a row of large boulders across the 125-foot river with a chute in the middle for kayakers and canoeists to glide through. The rock spillway will also help aerate the water, improving water quality, Anderson said.

"The ecology will get better, and we will no longer have an erosion issue with the dam," said Anderson, adding that rock was used to stabilize the stream bank. Other benefits from the free-flowing river include passage of fish and other aquatic species. It also favors native species, and there will be no future repair costs or maintenance.

This is also considered a trial run for removing two other dams on the Des Plaines River in Lake County at Route 60 and MacArthur Woods. Both of those are concrete dams, but first they will need to secure funding.

The Lake County Forest Preserve District has spent between $80,000 and $90,000 on engineering for the project and $500,000 on removal of the dam and restoration of the river. That money came from the district's bond fund.

The project was recommended by the Upper Des Plaines Phase II Flood Reduction Study that is being completed by the U.S. Army Corps of Engineers. There will be some flood control impact in that without the dam, nearby wetlands will be able to release the water they are holding so there will be more capacity in the wetland when it rains.

"Will it solve Des Plaines River flooding? No," Anderson said.

Now he would like to focus on the other two dams, which he said should be easier to disassemble.

"If not in the next five years, for sure in 10 years," he said.

Source: Lake Zurich Courier