70 ILCS 605/12-2

Lands within district-Rights of drainage.

Land included within a district shall continue to have the same rights of drainage, both common law and statutory, as land not within an organized drainage district, except insofar as the drainage system of the district may vary from or be inconsistent with natural drainage. The construction of a covered drain by a drainage district in the course of natural drainage or along the course of an open ditch shall not in itself be considered to be an abandonment of the natural drain or the open ditch.