RCW 88.32.060

Such commission shall also make, or cause to be made, an assessment roll, in which shall appear the names of the owners of the property assessed, so far as known, the description of each lot, block, parcel or tract of land within such assessment district, and the amount assessed against the same, as separate, special or particular benefits, and certify such assessment roll to the board of county commissioners, of such county, within ten weeks after their appointment, or within such further time as may be allowed by the board of county commissioners of such county.