40 ILCS 5/10-101

In forest preserve districts, the boundaries of which are coextensive with the boundaries of a county in which an annuity and benefit fund is created and set apart and is maintained and administered for county employees under Article 9 of this Code, a forest preserve district employees' annuity and benefit fund shall be created, set apart, maintained and administered for the employees of the forest preserve district, in the same manner as the fund created and set apart, maintained and administered for such county employees. The fund herein created may be referred to as the fund. The term "district" means a forest preserve district as above described.