Okla. Stat. tit. 61 § 4
All contracts hereafter made by or on behalf of the state, or by or on behalf of any county, city, township, or other municipality, with any corporation, person or persons, for the performance of any public work, by or on behalf of the state or any county, city, township, or other municipality, shall be deemed and considered as made upon the basis of eight (8) hours constituting a day's work; and it shall be unlawful for such corporation, person or persons to require, aid, abet, assist, connive at, or permit any laborer, workman, mechanic, prison guards, janitors in public institutions, or other person to work more than eight hours per calendar day in doing such work, except in cases and upon the conditions provided in Section 3 of this title.
Provided that the provisions of this act in regard to hours worked per calendar day shall not apply to the construction, reconstruction, maintenance, or the production of local materials for: Highways, roads, streets, and all the structures and drainage in connection therewith; sewer systems, waterworks systems, dams and levees, canals, drainage ditches, airport grading, drainage, surfacing, seeding and planting. Provided that the provisions of this act will not prevent employees from drawing time and half for those hours worked over forty (40) during any calendar week.
Okla. Stat. tit. 61, § 4