Every district shall consider the preservation of natural conditions and protection of flora and fauna as part of its principal purpose and to that end shall set aside a substantial portion of its land to remain in an essentially undisturbed condition.
A district is empowered to dedicate areas as nature preserves as provided in the "Illinois Natural Areas Preservation Act", as now or hereafter amended, and to cooperate with the Illinois Nature Preserves Commission in matters relating to the purposes of that Act.
70 ILCS 410/11