615 ILCS 5/24
Title to the bed of Lake Michigan and all other meandered lakes in Illinois, set forth in the 1962 Report of the Department of Public Works and Buildings, Division of Waterways, entitled "Meandered Lakes in Illinois", with Map Appendix, regardless of the location, size or shape is held in trust for the benefit of the People of the State of Illinois and the Department of Natural Resources is the agency designated as the trustee authorized to exercise administrative jurisdiction and control thereover in the execution of the powers and duties under this Act. It shall be the duty of the Department of Natural Resources, to carefully examine the shore lines of Lake Michigan, all other meandered lakes in Illinois and the Chicago River each year for the purpose of seeing that encroachments are not made upon or other unauthorized uses made of these bodies of water, and for the purpose of preventing any land being made along the said Chicago River, Lake Michigan or meandered lakes in such manner as might become an encroachment thereon.
The Department, for the purpose of preventing fills, deposits of any character, or encroachments or other unauthorized uses in or upon any of the lakes or rivers of this State, and for the protection of navigation upon any of the navigable rivers and lakes of this State, or such rivers and lakes as are capable of being made navigable by improvement, is hereby authorized and empowered to lay out and fix shore or harbor lines through any city or municipality, or at any other locality where public interests may require, and to authorize the construction of retaining walls under proper restrictions and conditions. Any person or persons, city or municipality, or other agency, desiring to erect such wall, shall first secure a permit therefor upon application to and submission of plans, profiles and specifications to said Department of Natural Resources, the line upon which said construction is to be placed to be fixed by survey by said Department. Whoever violates any of the provisions of this Section, or does any work herein designated without first obtaining a permit from the Department of Natural Resources, shall be guilty of a Class A misdemeanor.
615 ILCS 5/24