60 ILCS 1/115-5
As used in this Article, unless the context otherwise requires:
"Board" means the township board in counties having a population of more than 150,000.
"Development of real property" means the constructing, installing, planting or creating of any permanent or temporary improvement of real property that has been acquired for open space purposes.
"Open land" or "open space" means any space or area of land or water of an area of 50 acres or more, the preservation or the restriction of development or use of which would (i) maintain or enhance the conservation of natural or scenic resources; (ii) protect natural streams or water supply; (iii) promote conservation of soils, wet lands, or shores; (iv) afford or enhance public outdoor recreation opportunities; (v) preserve flora and fauna, geological features, historic sites, or other areas of educational or scientific interest; (vi) enhance the value to the public of abutting or neighboring highways, parks, or other public lands; (vii) implement the plan of development adopted by the planning commission of any municipality or county; or (viii) promote orderly urban or suburban development. A township at any time may release a specified parcel of land from an open space plan and allow the development of the parcel to occur. Once development (as defined in Section 115-55) has commenced, the land shall no longer be eligible for acquisition as open space or open land.
"Open space plan" means the written plan adopted by the board to implement an open space program and includes properly adopted amendments or additions to the plan.
"Open space program" means the acquisition of the fee or of a lesser right or interest in tracts of open land in the township for open space purposes.
"Open space purposes" includes (i) the preservation and maintenance of open land, scenic roadways, and pathways; (ii) the holding of real property described in clause (i), with or without public access, for the education, pleasure, and recreation of the public or for other open space values; (iii) the preservation of portions of that property in their natural condition and the development of other portions of that property; (iv) the management and use of that property in a manner and with restrictions that will leave it unimpaired for the benefit of future generations; and (v) otherwise promoting the conservation of the nature, flora and fauna, natural environment, and natural resources of the township.
60 ILCS 1/115-5