Okla. Stat. tit. 82 § 576
The board of directors shall also have the right and authority to enter into contracts or other arrangements with the United States Government or any department thereof, with persons, railroad or other corporations, with public corporations, cities and towns, and the state government of this or other states with drainage conservation, conservancy, or other improvement districts, in this or other states, for cooperation or assistance in constructing, maintaining, using and operating the works of the district or the waters thereof, not in violation of Article VI of the Constitution or for making surveys and investigations or reports; and may purchase, lease or otherwise acquire land or other property in adjoining states in order to secure outlets or spend money for securing such outlets or reservoirs or other works in adjoining states, and the Governor of the State of Oklahoma is hereby authorized to assist any conservancy district in negotiating any agreements with other states and the United States, under the power conferred upon him by Section 8 of Article VI of the Constitution of Oklahoma. That the streams constituting boundaries between this and other states for more than one hundred (100) miles shall not be organized within the conservancy districts until the state governments of this and other states affected shall have executed agreements as to equitable division of costs and benefits between the areas with different states affected by the agreement.
Okla. Stat. tit. 82, § 576