Okla. Stat. tit. 11 § 22-154
Nothing in the Oklahoma Municipal Utility Revenue Bond Act shall prevent a municipality from dedicating sales taxes or other municipal taxes as an additional source of payment and security for its utility revenue obligations, provided that the dedication of such tax revenue is approved by a majority of municipal voters voting at an election held for that purpose, in the manner set out in Section 2701 of Title 68 of the Oklahoma Statutes and other applicable laws, on a ballot question separate from the question of the issuance of revenue obligations. Further, nothing in the Oklahoma Municipal Utility Revenue Bond Act shall prevent a municipality from purchasing a policy of municipal bond insurance, securing a rating on the creditworthiness of the obligations, obtaining a letter of credit and other such credit enhancement product generally utilized in the public finance industry to further enhance and secure the obligations, provided, that at the time of the securing of such credit enhancement it reasonably appears to the governing body of the municipality that such credit enhancement shall result in a reduction in the amount of interest to be paid by the municipality over the life of the obligations, taking into account the cost of such credit enhancement. The dedication of such municipal taxes or the providing of credit enhancement for the obligations shall be at the sound discretion of the governing body of the municipality.
Okla. Stat. tit. 11, § 22-154