Okla. Const. art. X, § 27A

Any incorporated city or town in Oklahoma may individually or jointly, after approval of the proposition by a majority of the qualified electors voting in an election in each of said cities and towns, contract and pledge revenues for a term of years with other cities or towns, the State of Oklahoma, the United States of America, or any other governmental subdivision or agency of any of them, for the purpose of purchasing water, constructing, acquiring, or operating water facilities, or purchasing or leasing reservoir space. Any one or more incorporated cities and towns in Oklahoma may after approval of the proposition by a majority of the qualified electors voting in an election in each of said cities and towns issue bonds payable over a period not to exceed thirty (30) years and secured by revenues derived from the sale of water for the joint construction, acquisition, repair, extension or improvement of said water facilities; and thereafter enact ordinances giving effect to the provisions of this section. This section shall be independent and shall not be limited by or limit other existing provisions of the Constitution relating to municipal water or the financing thereof, nor shall it be exclusive as to other agencies of the State of Oklahoma authorized by law to incur indebtedness, Section 27 of Article X of the Constitution which pertains to incurring of tax secured indebtedness by cities and towns for public utilities is hereby amended to permit joint ownership by cities and towns of water facilities.