Wash. Rev. Code § 80.54.030
Whenever the commission shall find, after hearing had upon complaint by a licensee or by a utility, that the rates, terms, or conditions demanded, exacted, charged, or collected by any utility in connection with attachments are unjust, unreasonable, or that the rates or charges are insufficient to yield a reasonable compensation for the attachment, the commission shall determine the just, reasonable, or sufficient rates, terms, and conditions thereafter to be observed and in force and shall fix the same by order. In determining and fixing the rates, terms, and conditions, the commission shall consider the interest of the customers of the attaching utility or licensee, as well as the interest of the customers of the utility upon which the attachment is made.
RCW 80.54.030