Okla. Stat. tit. 11 § 37-127
An incorporated municipality of a state adjoining the State of Oklahoma is hereby granted permission, if authorized or empowered by the laws of such adjoining state to do so, to acquire by purchase from a private corporation which may be furnishing water to water users in the municipality, or which may be furnishing water to the municipality for resale to water users therein, the title to, or lesser interest in, lands that the private corporation owns in the State of Oklahoma. The municipality may also acquire any easements or rights-of-way then owned by such corporation over and across other lands within the State of Oklahoma necessary for pipelines to convey water from a reservoir to a point or points outside the State of Oklahoma. Such lands, easements and rights-of-way acquired by the municipality may be used in connection with, but only used in connection with, the establishment, betterment or expansion of a municipally-owned water supply or system; the necessary protection of the water supply from pollution; or the maintenance and operation of the municipally-owned water supply or system. The municipality may continue to hold lands, easements and rights-of-way so acquired as long as the same are so used. In order to transfer or convey any of its interests in Oklahoma lands, the private corporation shall have owned the title to, or any lesser interest in, lands within the State of Oklahoma as of April 25, 1957, upon which is located, in whole or in part, a reservoir from which such water or portion thereof is obtained, which reservoir has been in existence on the lands for more than one (1) year prior to April 25, 1957, and which land, or interest therein, has been owned by the corporation for more than fifteen (15) years prior to April 25, 1957.
Okla. Stat. tit. 11, § 37-127