Wash. Rev. Code § 39.50.020
Subject to any applicable budget requirements, any municipal corporation may borrow money and issue short-term obligations as provided in this chapter, the proceeds of which may be used for any lawful purpose of the municipal corporation. Short-term obligations may be issued in anticipation of the receipt of revenues, taxes, or grants or the sale of (1) general obligation bonds if the bonds may be issued without the assent of the voters or if previously ratified by the voters; (2) revenue bonds if the bonds have been authorized by ordinance; (3) local improvement district bonds if the bonds have been authorized by ordinance. These short-term obligations shall be repaid out of money derived from the source or sources in anticipation of which they were issued or from any money otherwise legally available for this purpose.
RCW 39.50.020