Kankakee River State Park is an Illinois state park on 4,000 acres (1,619Â ha) primarily in Kankakee and Will Counties, Illinois, United States. Originally, 35 acres (14Â ha) of land was donated by Ethel Sturges Dummer for the creation of the state park in 1938. Another 1,715 acres (694Â ha) was donated by Commonwealth Edison in 1956, which again donated more land in 1989. The islands of Smith, Hoffman, Langham, and Willow are all located inside the park on the Kankakee River.