RCW 35.13.200: Annexation of federal areas by second-class cities and towns—Annexation ordinance—Provisions.

In the ordinance annexing territory pursuant to a gift, grant, or lease from the government of the United States, a second-class city or town may include such tide and shore lands [tidelands and shorelands] as may be necessary or convenient for the use thereof, may include in the ordinance an acceptance of the terms and conditions attached to the gift, grant, or lease and may provide in the ordinance for the annexed territory to become a separate ward of the city or town or part or parts of adjacent wards.