RCW 35.13.210

A second-class city or town may cause territory annexed pursuant to a gift, grant, or lease of the government of the United States to be surveyed, subdivided and platted into lots, blocks, or tracts and lay out, reserve for public use, and improve streets, roads, alleys, slips, and other public places. It may grant or sublet any lot, block, or tract therein for commercial, manufacturing, or industrial purposes and reserve, receive and collect rents therefrom. It may expend the rents received therefrom in making and maintaining public improvements therein, and if any surplus remains at the end of any fiscal year, may transfer it to the city's or town's current expense fund.