ORS § 224.380
The State Treasurer may purchase sewerage bonds from a municipality or sanitary district at private sale if the municipality or district does not receive any bids for the bonds, or if bids received therefor are unsatisfactory. General obligation sewer bonds or sewerage system bonds, other than those issued pursuant to applications to pay assessments in installments, may be purchased by the State Treasurer under the provisions of ORS 224.310 to 224.420 only if the revenues of the sewerage system of the issuing municipality or district, or both, after the payment of operation and maintenance expenses, are pledged wholly to the payment of the principal of and the interest upon the said bonds, and the municipality and the sanitary district, if any, served by the sewerage system of a municipality covenant to levy ad valorem taxes upon all of the taxable property within their corporate limits to meet deficiencies in such revenues for such purposes, and only if the combined indebtedness for all public purposes, other than state or federal, within the boundaries of the municipality, including the proposed sewerage system indebtedness, but excluding obligations issued for other utilities that are self-supporting or self-liquidating or are approximately so, does not exceed 12-1/2 percent of the real market value of all property that is by law assessable for state and county purposes within the limits of the municipality. Notwithstanding that such revenues may have been pledged to the payment of the principal of and the interest upon a particular issue of general obligation bonds owned by the state, the same revenues, with the approval of the State Treasurer, may be pledged to the payment of the principal of and the interest on additional issues of such bonds purchased by the state from the municipality or district. The additional issues shall be on a parity with previous issues as to the pledge of such revenues for such purposes. Municipalities may provide that receipts from the payment of assessments levied under authority of chapter 593, Oregon Laws 1955, and the interest thereon shall be applied to payment of the principal of and the interest upon their general sewerage system bonds issued under authority of chapter 593, Oregon Laws 1955, rather than issue Bancroft or assessment bonds pursuant to such assessments. In order to complete the financing of a sewerage system, the State Treasurer may purchase issues of general obligation sewerage system bonds of municipalities or sanitary districts, payable only from ad valorem property taxes, provided the issues do not exceed the debt limits specified in this section. If, in addition to the net revenues of the sewerage system of the issuing municipality, the net revenues of the municipality-owned water system of the municipality that may become available in not more than five years from the issue date of the sewerage system bonds also are pledged to the said bonds, and the municipality further covenants to levy ad valorem taxes upon all the taxable property within its corporate limits to meet deficiencies in sewerage system and water system revenues for such purposes, the sewerage system bonds of the municipality may be purchased by the State Treasurer, provided the combined indebtedness for all purposes within the boundaries of the municipality, including the proposed sewerage system indebtedness, but excluding obligations issued for other utilities that are self-supporting or self-liquidating or are approximately so, does not exceed 15-3/8 percent of the real market value of the property within the limits of the municipality. This limitation shall include the ratios of indebtedness to real market value of other subdivisions that overlap the municipality to an extent of more that 12-1/2 percent of the real market value of all the taxable property of the municipality.
ORS 224.380