55 ILCS 5/5-25019
Any county which has established a county health department or any counties which have established a multiple-county health department may unite with one or more adjacent counties which have established county or multiple-county health departments, for the purpose of maintaining and operating a consolidated health department subject to the approval of the county boards involved and the Director of the Illinois Department of Public Health. In the event of approval by the county boards involved and the Director of Public Health, the chairman or president of each county board and of each board of health shall meet and immediately proceed to organize the consolidated health department. At such time as they shall agree concerning the conditions governing organization and operation, and the apportionment of the costs thereof, they shall select a date within 60 days on which the consolidated health department shall be established, and its operation and maintenance shall be in accordance with all provisions of this Division relating to county health departments except where otherwise prescribed for multiple-county health departments. The county or multiple-county health departments in counties joining together to operate and maintain a consolidated health department shall cease to function as independent health departments so long as the consolidation shall exist; shall transfer all records to the consolidated health department; and shall not withdraw from this union except in accordance with the provisions of Section 5-25020.
The board of health of each consolidated health department shall consist of the members of the boards of health of the county and multiple-county health departments involved except that members from counties which have previously established single county health departments shall be reduced to four, including at least one physician and one member of the county board. New appointments and reappointments shall be made in accordance with the provisions of Section 5-25012 relating to boards of health of multiple-county health departments. The consolidated board of health shall hold its first meeting no later than seven days after the date of establishment, for the purpose of organizing, electing officers, and carrying out its responsibilities in connection with the consolidated health department. Its subsequent meetings shall be held as prescribed in this Division for multiple-county health departments. Membership and actions of the consolidated board of health shall become official at its first meeting or on the date of establishment of the consolidated health department, whichever occurs at the earlier date. After a consolidated health department has begun operation, addition of other health departments to the consolidation may be accomplished with consent of all county boards of supervisors or commissioners concerned and the Director of Public Health; participation by such additional counties will be under the conditions selected in the original consolidation agreement, and date of entry into the consolidation and other relevant details will be arranged between the board of health of the consolidated health department, and the president of the county board and the chairman or president of the board of health of each county requesting admission to the consolidated health department.
55 ILCS 5/5-25019