525 ILCS 30/2
All areas within the State except those that are expressly designated by law for preservation and protection in their natural condition are liable to be altered by human activity. Natural lands and waters together with the plants and animals living thereon in natural communities are a part of the heritage of the people. They are of value for scientific research, for teaching, as reservoirs of natural materials not all of the potential uses of which are now known, as habitats for rare and vanishing species, as places of historic and natural interest and scenic beauty and as living museums of the native landscape wherein one may envision and experience primeval conditions in a wilderness-like environment. They also contribute generally to the public health and welfare and the environmental quality of the State.
It is therefore the public policy of the State of Illinois to secure for the people of present and future generations the benefits of an enduring resource of natural areas, including the elements of natural diversity present in the State, by establishing a system of nature preserves, protecting nature preserves and gathering and disseminating information regarding them, providing for appropriate use of nature preserves that will not damage them, establishing and maintaining a register of natural areas and buffer areas, providing certain forms of protection and control of registered natural areas and registered buffer areas and otherwise encouraging and assisting in the preservation of natural areas and features.
525 ILCS 30/2