(35 ILCS 200/10-155)
    Sec. 10-155. Open space land; valuation. In all counties, in addition to valuation as otherwise permitted by law, land which is used for open space purposes and has been so used for the 3 years immediately preceding the year in which the assessment is made, upon application under Section 10-160, shall be valued on the basis of its fair cash value, estimated at the price it would bring at a fair, voluntary sale for use by the buyer for open space purposes.
    Land is considered used for open space purposes if it is more than 10 acres in area and:
        (a) is actually and exclusively used for maintaining
or enhancing natural or scenic resources,
        (b) protects air or streams or water supplies,
        (c) promotes conservation of soil, wetlands, beaches,
or marshes, including ground cover or planted perennial grasses, trees and shrubs and other natural perennial growth, and including any body of water, whether man-made or natural,
        (d) conserves landscaped areas, such as public or
private golf courses,
        (e) enhances the value to the public of abutting or
neighboring parks, forests, wildlife preserves, nature reservations, sanctuaries, or other open spaces, or
        (f) preserves historic sites.
    Land is not considered used for open space purposes if it is used primarily for residential purposes.
    If the land is improved with a water-retention dam that is operated primarily for commercial purposes, the water-retention dam is not considered to be used for open space purposes despite the fact that any resulting man-made lake may be considered to be used for open space purposes under this Section.
(Source: P.A. 95-70, eff. 1-1-08.)