Wash. Rev. Code § 9.94.043
A person, other than a person serving a sentence in a penal institution of this state, is guilty of possession of contraband on the premises of a state correctional institution in the first degree if, without authorization to do so, the person knowingly possesses or has under his or her control a deadly weapon on or in the buildings or adjacent grounds subject to the care, control, or supervision of a state correctional institution. Deadly weapon is used as defined in RCW 9A.04.110: PROVIDED, That such correctional buildings, grounds, or property are properly posted pursuant to RCW 9.94.047, and such person has knowingly entered thereon: PROVIDED FURTHER, That the provisions of this section do not apply to a person licensed pursuant to RCW 9.41.070 who, upon entering the correctional institution premises, proceeds directly along an access road to the administration building and promptly checks his or her firearm(s) with the appropriate authorities. The person may reclaim his or her firearm(s) upon leaving, but he or she must immediately and directly depart from the premises.
Possession of contraband on the premises of a state correctional institution in the first degree is a class B felony.
RCW 9.94.043