Wash. Rev. Code § 35.21.088
Any city or town may create, by ordinance, an "equipment rental fund," hereinafter referred to as "the fund," in any department of the city or town to be used as a revolving fund to be expended for salaries, wages, and operations required for the repair, replacement, purchase, and operation of equipment, and for the purchase of equipment, materials, and supplies to be used in the administration and operation of the fund.
The legislative authority of a city or town may transfer any equipment, materials or supplies of any office or department to the equipment rental fund either without charge, or may grant a credit to such office or department equivalent to the value of the equipment, materials or supplies transferred. An office or department receiving such a credit may use it any time thereafter for renting or purchasing equipment, materials, supplies or services from the equipment rental fund.
Money may be placed in the fund from time to time by the legislative authority of the city or town. Cities and towns may purchase and sell equipment, materials and supplies by use of such fund, subject to any laws governing the purchase and sale of property. Such equipment, materials and supplies may be rented for the use of various offices and departments of any city or town or may be rented by any such city or town to governmental agencies. The proceeds received by any city or town from the sale or rental of such property shall be placed in the fund, and the purchase price of any such property or rental payments made by a city or town shall be made from moneys available in the fund. The ordinance creating the fund shall designate the official or body that is to administer the fund and the terms and charges for the rental for the use of any such property which has not been purchased for its own use out of its own funds and may from time to time amend such ordinance.
There shall be paid monthly into the fund out of the moneys available to the department using any equipment, materials, and/or supplies, which have not been purchased by that department for its own use and out of its own funds, reasonable rental charges fixed by the legislative authority of the city or town, and moneys in the fund shall be retained there from year to year so long as the legislative authority of the city or town desires to do so.
Every city having a population of more than eight thousand, according to the last official census, shall establish such an equipment rental fund in its street department or any other department of city government. Such fund shall acquire the equipment necessary to serve the needs of the city street department. Such fund may, in addition, be created to service any other departments of city government or other governmental agencies as authorized hereinabove.
RCW 35.21.088
Census to be conducted in decennial periods: State Constitution Art. 2 s 3.
Determination of population: Chapter 43.62 RCW.