Such bonds and other evidences of indebtedness and the interest thereon shall be paid by revenue derived from an annual assessment upon the ad valorem taxed property of the district, and all the ad valorem taxed property of the district, including the ad valorem taxed property of public service corporations, shall be and remain liable to be assessed for such payments as herein provided.
Okla. Stat. tit. 19, § 901.18