173 sites, open May 11-Sept. 9; The Cranberry Lake area is one of the largest remote areas remaining in the state. There has been only a minimum of civilized encroachment on the lake itself, and just to the south lie thousands of acres of unbroken forest. Originally, the lake was about half its present size, but in 1867, a log crib dam was completed at Cranberry Lake Village to control the flow of the river and improve navigation. The present concrete dam was built in 1916. The park is adjacent to 150,000 acres of forest preserve. There are many miles of marked trails and ponds.