Once the main channel of the Illinois River, Spring Lake is now geologically classified as a "meander scar," an abandoned channel of the river. Guarded by a high sandstone bluff, this 1,946-acre site is one of the few Illinois River floodplain components where upland pine forests still exist. The Spring Lake area possesses a total of 7.5 miles of hiking trails spread over 3 different trail systems. Besides hiking, these trails are also great for studying the bird, insect, and plant life associated with the site. Waterfowl watchers will want to utilize the numerous parking sites and day-use areas located along the 18 miles of lake shoreline.