Oregon Revised Statutes Utility Regulation § 758.305

(1) Designated service territories of a water utility approved by the Public Utility Commission shall be exclusive. A water utility or community water supply system shall not provide water utility service within the designated exclusive service territory of another water utility without the express approval of the commission.

(2) A water utility shall serve only customers within its designated exclusive service territory and shall serve all applicants for service within its designated territory. The water utility may refuse service only as provided by commission rule.

(3) Upon petition by the water utility for an order, or by the commission on its own motion, a designated service territory may be expanded to include unserved areas. In reviewing a petition, the commission shall consider at least the current ability of the water utility to serve the expanded area, the demand for service in the expanded area, the impact on existing customers and the availability of alternative service. The commission may take other factors into consideration as prescribed by commission rule. Notice and hearing of the proposed expansion shall be given as provided in ORS 758.302.

(4) Upon petition by the water utility or a customer of the utility for an order, or by the commission on its own motion, a designated exclusive service territory may be decreased upon a showing that the water utility is not providing adequate service to its customers or does not have the capacity to serve the designated area. Notice of the proposed decrease of service territory shall be given as provided in ORS 758.302.