The park contains such wildlife as deer, squirrels, rabbits, raccoons, eagles, hawks and 47 varieties of birds. At least 14 different ferns and over 500 different herbaceous plants and 165 varieties of flowers can be seen throughout the park. There are also three shelters, two are handicap accessible and may be reserved by obtaining a form from the park office. Playground equipment is provided in the youth group camping area and main picnic areas. Camping permits must be obtained at the park office.
Walnut Grove offers youth group camping and requires a reservation.
This reservation form may be obtained by contacting the park office. The Apple River has a variety of fish including smallmouth bass, sunfish, crappie, carp, and suckers. When economically feasible the Illinois Department of Natural Resources stocks Apple River with keeper-size trout. The river is one of several in the state where the department releases this fish. Trout require clean, clear, cold water and in the spring, Apple River meets these requirements.