615 ILCS 15/1
It is hereby recognized that the unregulated flow of the rivers and waters of the State of Illinois constitutes a menace to the general welfare of the people of this State, resulting in periods of destructive floods upon the rivers and waters of Illinois, upsetting the orderly processes of industry, agriculture and life in general, and causing loss of life and property, including the erosion of lands, the impairment and obstruction of their drainage, the impairment or destruction of surface water supplies for domestic use, the impairment or destruction of navigation, highways, railroads, and other channels of commerce within the State; and periods of inadequate low water flows wherein the public water supplies of cities and villages are dangerously reduced, facilities for public recreation are rendered inadequate, and the propagation and conservation of wild life is adversely affected.
It is the sense of this General Assembly that regulation of the flood and low water flows of the rivers and waters of Illinois is a proper activity of the State of Illinois, independently or in cooperation with the United States government, State agencies, units of local government and school districts; that investigations and improvements of the rivers and waters of Illinois, including the watersheds thereof, for the purpose of control of flood and low water flows, are in the interest of the general welfare of the People of Illinois; and that the State of Illinois should improve or participate in the improvement of the rivers and waters, including the watersheds thereof, for the purpose of regulating the flood and low water flows and the development and utilization of water, waterways and water resources if the benefits are in excess of the estimated costs, and if the lives and general welfare of the People of Illinois are adversely affected; except that for improvements limited to channelization, the benefits need not necessarily exceed the estimated costs.
615 ILCS 15/1