For the purpose of raising revenue for establishing, laying out, constructing, altering, repairing, improving, and maintaining county roads, bridges, and wharves necessary for vehicle ferriage and for other proper county purposes, the board shall annually at the time of making the levy for general purposes make a uniform tax levy throughout the county, or any road district thereof, of not to exceed two dollars and twenty-five cents per thousand dollars of assessed value of the last assessed valuation of the taxable property in the county, or road district thereof, unless other law of the state requires a lower maximum levy, in which event such lower maximum levy shall control. All funds accruing from such levy shall be credited to and deposited in the county road fund except that revenue diverted under RCW
36.33.220 shall be placed in a separate and identifiable account within the county current expense fund and except that revenue diverted under chapter
39.89 RCW shall be expended as provided under chapter
39.89 RCW.