There is hereby created a body corporate and politic to be known as the Water Conservation Storage Commission which may sue and be sued and plead and be impleaded. The Commission, where necessary to promote the optimum development and utilization of reservoir sites, shall have the power to acquire by purchase, gift, devise or eminent domain land and interests in land except mineral interests. The Commission is hereby constituted an instrumentality of the State of Oklahoma, and exercise by the Commission of the powers conferred by this act shall be deemed and shall be held to be an essential governmental function of the State of Oklahoma. The Commission shall be composed of the members of the Oklahoma Water Resources Board and the officers of said Oklahoma Water Resources Board shall be the officers of the Commission. The duties assigned to each member of the Commission by the provisions of this act shall be considered additional duties to those required by virtue of their membership on the Oklahoma Water Resources Board, and they shall not receive any additional compensation for the performance of the duties required by this act, except that they shall be entitled to their actual expenses incurred, and reimbursement for such expenses shall be paid out of the funds available for the operation of their department, on the same basis as now provided by law.