Okla. Const. art. X, § 9A

For the purpose of maintaining or aiding in maintaining a department of health within any county of the State, an additional levy not to exceed two and one-half mills on the dollar of the assessed valuation of the county may be levied annually, when such levy is approved by a majority of the qualified ad valorem tax paying voters of the county, voting on the question at an election called for such purpose by the Board of County Commissioners, or by initiative petition by voters of a county. A maximum levy of two and one-half mills may be made for such purpose after such approval until repealed by a majority of the qualified ad valorem tax paying voters of the county, voting on the question at an election called for such purpose by the Board of County Commissioners, or by initiative petition by voters of a county. Such department of health may be maintained jointly or in conjunction with one or more counties, cities, towns or school districts, or any combination thereof, and shall be maintained as now or hereafter provided by law. Nothing herein shall prohibit other levies or the use of other public funds for such department of health.