Reef construction provides a man-made assist for Lake Michigan fish and wildlife
A project to restore and connect 1.5 miles of coastal fish habitat is underway from a barge in Lake Michigan at the Fort Sheridan Forest Preserve.
Just offshore, a crane methodically is placing slabs of native limestone, glacial boulders and cobbles, and large woody debris such as tree trunks and root wads on the lake bottom as a man-made assist for fish and wildlife.
The materials may be rough but the placement to create a submerged habitat is precise. The contractor is following GPS coordinates and examining the progress with sonar to create domes and linear structures containing nooks, crannies and other spaces that mimic natural reefs found on the coastline.
"There's a deliberate design we're following," said Nicole Toth, project manager for the U.S. Army Corps of Engineers. "Our engineers created the design in cooperation with our biologists."
The structures are being built in two clusters north and south of Cliff Road in about 10 to 13 feet of water. When finished, the man-made reef will be about four to seven feet beneath the surface. Buoys will be installed to guide boaters.
The habitat is meant as a welcoming place for the state-threatened mudpuppy salamander; fish such as yellow perch, small mouth bass and walleye; and migratory water birds.
Ecologists have found wildlife diversity in the lake has been limited by a decrease in habitat types, according to the Lake County Forest Preserve District, which is partnering with the Army Corps for this part of the project.
"When you build the right habitat the species that are supposed to be there will increase in numbers," said Jim Anderson, the forest preserve district's director of natural resources.
"There are a lot of species near shore that need structure on the bottom rather than just sand or clay."
The reefs themselves will occupy about 1.4 acres of underwater space, but the benefits should extend farther because of the expected congregation of many animal species in the vicinity, Anderson said.
Five sandbar-like structures also are part of the project. Habitat improvement is the main goal but together all the elements may have a secondary benefit, Anderson said.
"Putting these structures in the water can have an impact on biodiversity and provide some shoreline stabilization," he added.
"Everybody on Lake Michigan - all the Great Lakes for that matter - are looking at options like this."
The Army Corps' Chicago district has 14 Great Lakes Fishery and Ecosystem Restoration projects totaling 1,105 acres built or under construction, mostly in urban areas.
Construction at Fort Sheridan, a former Army base which operated from 1887 to 1993, began Aug. 10 and is expected to last 10 weeks.
The man-made reefs are the second part of a $14 million project to connect and restore 1.5 miles of coastal habitats to their natural state.
Phase 1, which was on land, began five years ago and is nearly complete. Work included restoring 75 acres within four main ravines; 40 acres of bluff; and 12 acres of dune along the coastline, as well as about 60 acres of associated woodland.
The intent is to benefit rare and endangered ravine and coastal plants and animals without disrupting existing high-quality patches of habitat, according to the Army Corps.
Besides the Army Corps and forest preserve district, Phase 1 participants included Openlands, the city of Lake Forest and Lake Forest Open Lands Association.
"It's been a process and we've had a lot of partners involved," Anderson said.
The federal government is funding 65%, about $9.1 million, of the cost.
The forest preserve district has contributed about $2.6 million.