70 ILCS 3715/21

If the trustees determine that the leasing of the zone of land adjacent to the reservoir will aid in the protection from pollution or other injury to the reservoir by promoting forestation and other desirable vegetation and the improvement, maintenance and care of the premises, to zone such area for residential and business purposes and to lease its real estate for not more than 99 years to proper custodians for such uses and upon such terms and conditions as it determines are for the best interests of the authority and the purposes for which it was created.