After years of planning, the long process of pulling the plug on a hidden man-made lake in the Ethel's Woods Forest Preserve near Antioch is about to begin.
The Lake County Forest Preserve District board on Tuesday approved measures involved with the project to drain Rasmussen Lake and restore the North Mill Creek channel.
"It's a beautiful looking lake, but beneath there are some real problems," said Randy Seebach, the district's director of planning, conservation and development.
A key action was awarding a contract for about $1.2 million to Kovilic Construction Co., Inc., of Franklin Park. The work involves building a temporary holding structure and controls to slowly draw down the lake level and allow the new stream channel to emerge.
The Illinois Environmental Protection Agency will provide $500,000 toward the cost.
"We're excited to have the opportunity to actually remove the lake, slowly drain it down ... and turn it into the original stream that was there at one time," Seebach said.
This portion is expected to take 18 months to two years.
"We have to be cautious about the sediment. We don't want that to move downstream," said Jim Anderson, the district's natural resource manager.
The 57-acre lake was created in the mid-1950s by a private land owner who built an earthen dam and concrete spillway across Mill Creek. In 2001, the district bought the property east of Route 45 and south of Route 173 and established the Ethel's Woods Forest Preserve.
The lake is a main feature of Ethel's Woods but it is packed with several feet of sediment and has high phosphorous and low oxygen levels. In terms of quality, it is ranked 161 of the 162 lakes monitored by the Lake County Health Department.
"Dams hold and store pollutants and nutrients instead of cleaning them," Seebach said. "It's a man-made barrier to the natural cleansing process."
District officials at one time considered actions to make the lake accessible to the public but the shoreline is severely eroded with steep drop offs. Dredging the lake and making the shoreline safe for visitors was determined to be too costly.
"This is a better option for us," Anderson said. The decision to drain the lake was made in 2007, and the time since has been spent creating an acceptable construction plan and securing permits.
Water will be slowly released, and as the lake level decreases the sediment along the banks and eventually the lake bottom will gradually dry in place.
At that point the sediment will be contoured, the banks restored and the stream corridor reestablished with native vegetation, pools and riffles and other features.
Ethel's Woods, which has no public facilities, will be closed for the duration of the project.