Why a dip in Lake Michigan at Fort Sheridan Forest Preserve or its new addition isn't allowed

An apparent military device likely from another era washed up at the Lakeshore Preserve at Fort Sheridan on Lake Michigan over the weekend and was destroyed without issue, authorities said.

Lake County Forest Preserve officials say the situation reported and addressed over a few hours Saturday afternoon illustrates why swimming or even wading is not allowed in the area.

According to Ty Kovach, executive director of the Lake County Forest Preserve District, a couple walking along the beach saw what appeared to be old military device and reported it to local police, who alerted forest preserve authorities.

"They did the right thing," he said of the walkers. "It's an old military base and those things are out there."

Kovach said he didn't see the unidentified object in person but in a photo it appeared to be about a foot long. The district didn't want to take any chances, he added.

"We ended up calling the Waukegan bomb squad," he said. A bomb technician with the Waukegan Fire Department consulted with military personnel.

"It was determined that it was a live device and that it should not be moved," said Fire Marshal Todd Zupec. "Our bomb technician used equipment to destroy the device in place and render it safe."

Kovach said a large perimeter along the beach was secured while this was happening but the preserve was not closed to the public during the situation.

Kovach said the area was used as a gunnery range for decades.

Ron Davis, the forest preserves' public safety director, said a theory is that it came in at high tide.

"Exactly what was found, we don't know. It was just a piece of old military ordnance," Davis said. "It might have been something that was sitting on the bottom of the lake for decades that just got churned up."

The Lakeshore Preserve includes a mile of Lake Michigan shoreline. This summer, the 72-acre property was transferred from Openlands, a conservation organization, as an addition to the adjacent Fort Sheridan Forest Preserve.

Besides bluffs, ravines and other natural features, the connected properties include about two miles of Lake Michigan shoreline. Both are part of the former Fort Sheridan Army base that opened in 1889 and operated for about a century.

In April 2021, Openlands closed the preserve for public use due to safety concerns after a grenade and two flares - remnants of the site's history as an Army base - were found. The grounds were investigated and deemed clear. The preserve was reopened for the Labor Day weekend.

Kovach said the potential presence of ordnance as well as rebar, concrete and other debris in the water is why swimming isn't allowed. Large signs in English and Spanish in the area caution visitors that munitions may be present and to "recognize, retreat, report."

"I hope we don't have anything like this again but that's wishful thinking," Kovach said.