Okla. Stat. tit. 19, § 19-8.2: Authority to adopt or amend county home rule charter

Any county in this state with a population of less than five

hundred fifty thousand (550,000), according to the latest Federal

Decennial Census, which contains a metropolitan area with a

population of two hundred fifty thousand (250,000) or more,

according to the latest Federal Decennial Census, may adopt or amend

a County Home Rule Charter for county government which specifies

those powers appropriate for said government and which are not

inconsistent with the Oklahoma Constitution and laws of this state.