525 ILCS 30/15

Any public agency or instrumentality of the State and its political subdivisions has the power, and is urged, to dedicate suitable areas or portions of areas within its holdings and to continue holding them as nature preserves. Any public agency or instrumentality holding a natural area with the intention of preserving natural conditions thereon or for a purpose the Commission determines to be compatible with dedication of the area as a nature preserve shall dedicate it, subject to approval of the Commission and the Governor.