Mo. Rev. Stat. § 91.680

All moneys received from any bonds issued and all other income pursuant to sections 91.620 to 91.770, after reimbursements and repayment to said city or town of all amounts advanced for preliminary expenses, shall be applied solely to the payment of the costs of the works, extensions, operation, maintenance, improvements or betterments or to the appurtenant sinking fund and there shall be and hereby is created and granted a lien upon such moneys, until so applied, in favor of the holders of the bonds or the trustees herein provided for.