Wash. Rev. Code § 35.42.210
If at the time an option to purchase is exercised the remaining amount to be paid in order to purchase the real or personal property leased after crediting the rental payments toward the total purchase price therefor does not result in a total indebtedness in excess of one and one-half percent of the taxable property of such city or town computed in accordance with RCW 39.36.030, such a city or town may exercise its option to purchase such property. If such remaining amount to be paid to purchase such leased property will result in a total indebtedness in excess of one and one-half percent of the taxable property of such city or town, a proposition in regard to whether or not to purchase the property shall be submitted to the voters for approval or rejection in the same manner that bond issues for capital purposes are submitted to the voters.
RCW 35.42.210