Wash. Rev. Code § 36.69.300
Any person desiring to have such a special assessment against a tract of land segregated to apply to smaller parts thereof shall apply to the board of park and recreation commissioners of the park and recreation district which levied the assessment. If the board determines that a segregation should be made, it shall by resolution order the county treasurer to make segregation on the original assessment roll as directed in the resolution. The segregation shall be made as nearly as possible on the same basis as the original assessment was levied, and the total of the segregated parts of the assessment shall equal the assessment before segregation. The resolution shall describe the original tract, the amount and date of the original assessment, and shall define the boundaries of the divided parts and the amount of the assessment chargeable to each part. A certified copy of the resolution shall be delivered to the county treasurer who shall proceed to make the segregation ordered upon being tendered a fee of three dollars for each tract of land for which a segregation is to be made. In addition to such charge the board may require as a condition to the order of segregation that the person seeking it pay the district the reasonable engineering and clerical costs incident to making the segregation.
RCW 36.69.300