70 ILCS 810/40
The corporate authorities of forest preserve districts, having the control or supervision of any forest preserves, may erect and maintain within such forest preserves, under the control or supervision of such corporate authorities, edifices to be used for the collection and display of animals as customary in zoological parks, and may collect and display such animals, or permit the directors or trustees of any zoological society devoted to the purposes aforesaid to erect and maintain a zoological park and to collect and display zoological collections within any forest preserve now or hereafter under the control or supervision of such forest preserve district, out of funds belonging to such zoological society, or to contract with the directors or trustees of any zoological society on such terms and conditions as may to such corporate authorities seem best, relative to the erection, operation and maintenance of a zoological park and the collection and display of such animals within such forest preserve, out of the tax provided in Section 41.
Such forest preserve district may charge, or permit such zoological society to charge an admission fee. The proceeds of such admission fee shall be devoted exclusively to the operation and maintenance of such zoological park and the collections therein. All such zoological parks shall be open to the public without charge for a period equivalent to 52 days each year. Beginning on the effective date of this amendatory Act of the 101st General Assembly through June 30, 2022, any such zoological parks shall be open to the public without charge for a period equivalent to 52 days. All such zoological parks shall be open without charge to organized groups of children in attendance at schools in the State. The managing authority of the zoological park may limit the number of any such groups in any given day and may establish other rules and regulations that reasonably ensure public safety, accessibility, and convenience, including but not limited to standards of conduct and supervision. Charges may be made at any time for special services and for admission to special facilities within any zoological park for the education, entertainment or convenience of visitors.
70 ILCS 810/40