Olson Beach at Rock Cut State Park will be closed for swimming due to siltation of the lake.
The Illinois Department of Natural Resources made the announcement Monday.
The DNR says the siltation of the lake, along with warmed water temperatures and the shallow depth of the lake, has diminished the water quality of Olson Lake.
As of right now, a spokesman said it's closed for the season and there are no plans to re-open it. It was never intended to be a swimming beach, according to the spokesman.