Okla. Stat. tit. 82, § 82-1085.3: State to be divided into water districts

The Oklahoma Water Resources Board shall, from time to time as

may be necessary for the economical and satisfactory apportionment

of the water, divide the state in conformity with the drainage

areas, into water districts to be designated by name and to

comprise, as far as possible, one or more distinct stream systems in

each district. The districts may be changed from time to time as

may in its opinion be necessary for the economical and satisfactory

apportionment of the water.