Oregon Revised Statutes Cities § 224.140

A city, through its council, may enact and enforce such ordinances and other provisions as may be necessary or essential for the proper policing, protection, management and control of sewers, ditches, canals and other works beyond the city limits and constructed by the city under or by virtue of ORS 224.010 to 224.170. The city may construct extensions, laterals and branches to such sewer system upon the terms and provisions applicable to original construction.