Wash. Rev. Code § 36.68.010
Counties may establish park and playground systems for public recreational purposes and for such purposes shall have the power to acquire lands, buildings and other facilities by gift, purchase, lease, devise, bequest and condemnation. A county may lease or sell any park property, buildings or facilities surplus to its needs, or no longer suitable for park purposes: PROVIDED, That such park property shall be subject to the requirements and provisions of notice, hearing, bid or intergovernmental transfer as provided in chapter 36.34 RCW: PROVIDED FURTHER, That nothing in this section shall be construed as authorizing any county to sell any property which such county acquired by condemnation for park or playground or other public recreational purposes on or after January 1, 1960, until held for five years or more after such acquisition: PROVIDED FURTHER, That funds acquired from the lease or sale of any park property, buildings or facilities shall be placed in the park and recreation fund to be used for capital purposes.
RCW 36.68.010