615 ILCS 15/2
The Department of Natural Resources is hereby authorized and directed to make examinations and surveys, prepare plans and estimates for, and to construct, reconstruct, control, maintain, and operate, or supervise the construction, reconstruction, control, maintenance and operation of all works for the control of floods, the improvement of upland and bottom land drainage and the conservation of low water flows in the rivers and waters of Illinois, including the watersheds thereof, either independently or in cooperation with the United States government, State agencies, units of local government and school districts in connection with such work. However, no expenditure of funds for the improvement of any of the rivers and waters of Illinois, including the watersheds thereof, for the purpose of controlling flood flows, the improvement of bottom land and upland drainage, or the conservation of low water flows, shall be lawful until an appropriation for the improvement or improvements has been made by the General Assembly. No funds shall be expended on any rivers and waters improvement or improvements unless the works proposed by the improvement or improvements are in conformity with a report of survey made and filed as provided in Section 5 of this Act.
615 ILCS 15/2