Okla. Stat. tit. 11 § 11-115
The city treasurer shall be an officer of the city, appointed by the mayor for an indefinite term. The council may provide by ordinance that the same person may hold both the office of city clerk and the office of city treasurer. Said council may also provide by ordinance that the city clerk shall be ex officio city treasurer and that an acting city clerk shall be ex officio acting city treasurer. Subject to such regulations as the council may prescribe, the city treasurer shall deposit daily funds received for the city in depositories as the council may designate. The city treasurer shall have such other powers, duties, and functions related to his statutory duties as may be prescribed by law or by ordinance. The person who serves as city treasurer may be employed by the city to perform duties not related to his position as city treasurer. The salary, if any, for said duties shall be provided for separately by ordinance.
Okla. Stat. tit. 11, § 11-115