ORS § 757.500
When any public utility is primarily engaged in another enterprise and is only indirectly engaged in the production, transmission, delivery or furnishing of heat, light, water or power to or for the public by reason of a contract or agreement, express or implied, between itself and another public utility which is directly engaged in such business, the jurisdiction of the Public Utility Commission over such public utility extends only to the right to modify, control, rescind, alter or amend any such existing contract or agreement where the interest of the customers of such public utility directly engaged in such business demands. No such contract or agreement is valid or enforceable until it has been approved by the commission as being in the public interest.
ORS 757.500