410 ILCS 635/4
The Illinois Department of Public Health shall administer and enforce this Act. However, any local unit of government with a population of 1,000,000 or more and having or contracting with a health department with a qualified administrative and inspectional staff meeting the personnel standards promulgated by the Illinois Department of Public Health, may administer and enforce this Act by adopting an ordinance containing provisions for enforcement and penalties, and adopting by reference the rules and regulations promulgated and amended from time to time by the Department under the authority of this Act. A local unit of government that is so qualified and elects to administer and enforce this Act shall furnish the Department a copy of its ordinance and the names and qualifications of the employees required by this Act. When it is determined by the Department that the local unit of government is not administering or enforcing the approved local ordinance in an approved manner, such local unit of government shall be notified in writing and given a reasonable time to improve its administration and enforcement of the approved ordinance. During this time period, the Department may make inspections or take enforcement action as necessary to insure compliance with the provisions of this Act. If after such notice and time allowed the local unit of government is unable to administer and enforce the approved ordinance in an approved manner, the approval to administer and enforce this Act shall be revoked and the administration and enforcement of this Act shall revert to the Department.
Dairy farms, milk plants, receiving stations, cleaning and sanitizing facilities, transfer stations, and milk hauler-samplers in jurisdictions under a local ordinance at the time of the effective date of this Act will be subject to the local ordinance in lieu of this Act until July 1, 1986, or until the date prior to July 1, 1986, when the local ordinance is brought into compliance with this Act.
410 ILCS 635/4