The standard of measurement of the flow of water shall be the cubic foot per second of time; the standard measurement of the volume of water shall be the acre-foot, being the amount of water upon an acre covered one foot deep, equivalent to forty-three thousand five hundred sixty (43,560) cubic feet, or 325,851 U.S. gallons. [82:105.28]
Okla. Admin. Code § 785:20-11-6