70 ILCS 2605/4.16
The Director shall investigate the efficiency of all officers and employees and of all groups of officers and employees in the classified service and shall report to each officer, board or other authority in charge of any office or department of the sanitary district its findings and recommendations relative to increasing efficiency and economy therein. In case the recommendations made by the Director are not carried into effect within a reasonable time, or in case of a difference of opinion with reference to such findings or recommendations between the Director and the officer, or authority in charge of an office or department concerned in any such findings or recommendations, the report, accompanied by a note of the relevant facts shall be transmitted to the board of trustees for its final decision. The Civil Service Board shall investigate the enforcement of this Act and the rules adopted pursuant to this Act of the conduct of the appointees in the classified service and the methods of administration therein, and may investigate the nature, tenure and compensation of all offices and places in the civil service of the sanitary district. In the course of such investigation the Civil Service Board shall have power to administer oaths and to secure by subpoena both the attendance and testimony of witnesses and the production of books and papers.
70 ILCS 2605/4.16