Wash. Rev. Code § 64.08.090
The superintendents, associate and assistant superintendents, business managers, records officers, and camp superintendents of any correctional institution or facility operated by the state of Washington are hereby authorized and empowered to take acknowledgments on any instruments of writing, and certify the same in the manner required by law, and to administer all oaths required by law to be administered, all of the foregoing acts to have the same effect as if performed by a notary public: PROVIDED, That such authority shall only extend to taking acknowledgments for and administering oaths to officers, employees, and residents of such institutions and facilities. None of the individuals herein empowered to take acknowledgments and administer oaths shall demand or accept any fee or compensation whatsoever for administering or taking any oath, affirmation, or acknowledgment under the authority conferred by this section.
In certifying any oath or in signing any instrument officially, an individual empowered to do so under this section shall, in addition to his or her name, state in writing his or her place of residence, the date of his or her action, and affix the seal of the institution where he or she is employed: PROVIDED, That in certifying any oath to be used in any of the courts of this state, it shall not be necessary to append an impression of the official seal of the institution.
RCW 64.08.090