Oregon Revised Statutes Chapter 450 § 450.895 — Bonds,

Bonds, general obligation or revenue or combination of both; bonds to mature serially and be paid in installments. The authority may, when authorized by a majority of the votes cast at an election by electors of the authority, issue general obligation bonds or revenue bonds, or a combination of both, for the purpose of paying the cost of acquisition or construction, operation and maintenance of sewage treatment plants or trunk or lateral sewers or drains for any area or areas within the authority or to carry out any other purpose authorized under ORS 450.600 to 450.989. Each issue of general obligation bonds shall be the general obligation of the entire authority but shall be the primary obligation of the area directly benefited by the sewage treatment plant or trunk or lateral sewers or drains constructed with the proceeds of each issue of such bonds and paid by assessment, annual levy or sewer service charges, or combinations thereof, as determined by the board under ORS 450.855. Revenue bonds shall be payable solely out of designated revenues of the authority and shall not be deemed to be a general obligation of the authority or a charge upon its tax revenues. All bonds issued shall mature serially within not to exceed 30 years from date of issue, and shall be paid in annual installments of such amounts as will make the combined amount of principal and interest payable each year as nearly equal as practicable during the years of payment. [1955 c.614 §41]