Oregon Revised Statutes Education and Culture § 341.616

(1) The district board shall ascertain and levy annually, in addition to all other taxes, a direct ad valorem tax on all the taxable property within the district if the district approved bonded indebtedness or within the affected service area or combination of service areas if the service area or combination of service areas approved bonded indebtedness. The ad valorem tax shall be sufficient to pay promptly, when and as payments become due, the maturing interest and principal of all bonds outstanding for the district or the service area or combination of service areas that were approved at an election held pursuant to ORS 341.611 or 341.678. The amount of the tax may be increased by an amount sufficient to retire any bonds that may be callable.

(2) Funds derived from a tax levy within the district or the service area or service areas specifically for the purpose of paying bonded indebtedness shall be applied solely to the payment of the bonds for which the taxes were levied and may not be applied to the payment of any other indebtedness.