615 ILCS 5/5

The Department of Natural Resources shall upon behalf of the State of Illinois, have jurisdiction and supervision over all of the rivers and lakes of the State of Illinois, wherein the State of Illinois or the people of the State have any rights or interests, and shall make a list by counties of all the waters of Illinois, showing the waters, both navigable and non-navigable, that are found in each county of the State, and if the same are lakes, the extent of the shore lines and the amount, extent and area of the water surface; and in a like way, if the same are rivers, and specifying whether the same are navigable or non-navigable, and whether they have or have not been meandered.