A cumulative reserve fund is created pursuant to RCW 35.21.070 to be used for the purpose of constructing and repairing roads, streets, alleys and sidewalks for the street department of the city as shall be determined by the majority vote of the commissioners of the city. All funds budgeted or levied for such fund shall be placed in said fund and shall be used for the purpose above set forth and for no other purposes except as provided by law. (Prior code § 1.80.020.)