Wash. Rev. Code § 80.04.015
Whether or not any person or corporation is conducting business subject to regulation under this title, or has performed or is performing any act requiring registration or approval of the commission without securing such registration or approval, shall be a question of fact to be determined by the commission. Whenever the commission believes that any person or corporation is engaged in any activity without first complying with the requirements of this title, it may institute a special proceeding requiring such person or corporation to appear before the commission at a location convenient for witnesses and the production of evidence and produce information, books, records, accounts, and other memoranda, and give testimony under oath as to the activities being conducted. The commission may consider any and all facts that may indicate the true nature and extent of the operations or acts and may subpoena such witnesses and documents as it deems necessary.
After investigation, the commission is authorized and directed to issue the necessary order or orders declaring the activities to be subject to, or not subject to, the provisions of this title. In the event the activities are found to be subject to the provisions of this title, the commission shall issue such orders as may be necessary to require all parties involved in the activities to comply with this title, and with respect to services found to be reasonably available from alternative sources, to issue orders to cease and desist from providing jurisdictional services pending full compliance.
In proceedings under this section, no person or corporation may be excused from testifying or from producing any information, book, document, paper, or account before the commission when ordered to do so, on the ground that the testimony or evidence, information, book, document, or account required may tend to incriminate him or her or subject him or her to penalty or forfeiture specified in this title; but no person or corporation may be prosecuted, punished, or subjected to any penalty or forfeiture specified in this title for or on account of any account, transaction, matter, or thing concerning which he or she shall under oath have testified or produced documentary evidence in proceedings under this section: PROVIDED, That no person so testifying may be exempt from prosecution or punishment for any perjury committed by him or her in such testimony: PROVIDED FURTHER, That the exemption from prosecution in this section extends only to violations of this title.
Until July 1, 1994, in any proceeding instituted under this section to determine whether a person or corporation owning, controlling, operating, or managing a water system is subject to commission regulation, and where the person or corporation has failed or refused to provide sufficient information or documentation to enable the commission to make such a determination, the burden shall be on such person or corporation to prove that the person's or corporation's operations or acts are not subject to commission regulation.
RCW 80.04.015