Washington Revised Code Title 35. Cities and Towns § 35.50.020. Assessment lien--Validity

(1) That the contract for the improvement was not awarded in the manner or at the time required by law; or

(2) That the assessment was made by an unauthorized officer or person if the assessment roll was confirmed by the city or town authorities; or

(3) That the assessment is based upon a front foot basis, or upon a basis of benefits to the property within the improvement district unless it is made to appear that the city or town authorities did not act in good faith and did not attempt to act fairly in regard thereto or unless it is made to appear that the city or town authorities acted fraudulently or oppressively in making the assessment.

All local improvement assessments heretofore or hereafter made by city or town authorities in good faith are valid and in full force and effect.