Wash. Rev. Code § 36.34.220
If the board of county commissioners of any county adjudges that it is desirable and for the general welfare and benefit of the people of the county and for the interest of the county to lease or convey property, real or personal, belonging to the county, however acquired, whether by tax foreclosure or in any other manner, to the United States for the purpose of flood control, navigation, power development, or for use in connection with federal projects within the scope of the federal reclamation act of June 17, 1902, and the act of congress of August 30, 1935, entitled "An Act authorizing the construction, repair, and preservation of certain public works on rivers and harbors, and for other purposes," and federal acts amendatory thereof and supplemental thereto, for the reclamation and irrigation of arid lands, the board, by majority vote, may lease or convey such property to the United States for flood control, navigation, and power development purposes, or for use in connection with federal projects for the reclamation and irrigation of arid lands. This property may be conveyed or leased by deed or other instrument of conveyance or lease without notice and upon such consideration, if any, as shall be determined by the board and the deed or lease may be signed by the county treasurer when authorized to do so by resolution of the board. Any deed issued heretofore by any county to the United States under authority of section 1, chapter 46, Laws of 1937 and the amendments thereto, is ratified and approved and declared to be valid.
RCW 36.34.220