40 ILCS 5/13-204
"Employee": (a) Any employee of the Water Reclamation District appointed to the classified civil service under the Metropolitan Water Reclamation District Act or any employee exempt from civil service under that Act, including any person absent from such position due to assignment to any other position of employment for the District; (b) any temporary employee of the District; (c) all appointed officers or acting officers of the District; (d) any employee of the Retirement Board; and (e) any member of the Board of Commissioners of the District who elects to participate in the Fund within 90 days after becoming a member.
No person shall be an employee hereunder whose duties will not ordinarily permit 120 days of service during one calendar year.
A member of the Civil Service Board of the District who is first appointed to that office on or after the effective date of this amendatory Act of 1997 is not, by virtue of holding that office, an "employee" for the purposes of this Article.
40 ILCS 5/13-204