Wash. Rev. Code § 36.61.120
After a lake or beach management district is created, the county shall prepare a proposed special assessment roll. A separate special assessment roll shall be prepared for annual special assessments if both annual special assessments and special assessments paid at one time are imposed. The proposed special assessment roll shall list:
At the time, date, and place fixed for a public hearing, the county legislative authority shall act as a board of equalization and hear objections to the special assessment roll, and at the times to which the public hearing may be adjourned, the county legislative authority may correct, revise, raise, lower, change, or modify the special assessment roll or any part thereof, or set the proposed special assessment roll aside and order a new proposed special assessment roll to be prepared. The county legislative authority shall confirm and approve a special assessment roll by adoption of a resolution.
If a proposed special assessment roll is amended to raise any special assessment appearing thereon or to include omitted property, a new public hearing shall be held. The new public hearing shall be limited to considering the increased special assessments or omitted property. Notices shall be sent to the owners or reputed owners of the affected property in the same manner and form and within the time provided for the original notice.
Objections to a proposed special assessment roll must be made in writing, shall clearly state the grounds for objections, and shall be filed with the governing body prior to the public hearing. Objections to a special assessment or annual special assessments that are not made as provided in this section shall be deemed waived and shall not be considered by the governing body or a court on appeal.
RCW 36.61.120