Wash. Rev. Code § 85.06.600
At the time and place fixed in said order for the hearing of said petition, or at such time to which the court may continue said hearing, the court shall proceed to a hearing upon said petition and upon any objections or exceptions which have been filed thereto. And upon it appearing to the satisfaction of the court from the proofs offered in support thereof that the allegations of said petition are true, the said court shall ascertain the total amount of said registered warrants, orders, vouchers, or other evidences of indebtedness with the accrued interest and the costs of said proceedings, and thereupon the said court shall enter an order directing the board of county commissioners to levy a tax upon all the real estate within said drainage district exclusive of improvements, taking as a basis the last equalized assessment of said real estate for state and county purposes, sufficient to pay said outstanding registered warrants, orders, vouchers, or other evidences of indebtedness with interest as aforesaid and the costs of said proceeding, and the cost of levying said tax, and further directing the county auditor to issue a warrant on the county treasurer to the petitioner for the costs advanced by him or her in such proceeding, which shall be paid in the same manner as the said registered warrants, orders, vouchers, or other evidences of indebtedness.
RCW 85.06.600