Wyo. Stat. § 41-9-247
Omission to assess benefits, or to assess for construction, or to make additional assessment, or to make assessment for repairs, or to award damages to any one (1) or more tracts of land or easements in a drainage district, or to assess benefits, or to assess for construction, or to assess for repairs, or to make additional assessments against any corporation which should have been assessed, shall neither affect the jurisdiction of the court to confirm the report nor to render the benefits assessed, or the assessments for construction, or additional assessments, or assessments for repairs against other lands, or assessments against any corporation voidable, but the commissioners of said drainage district shall thereafter, as soon as they discover the omission, or as soon as notice thereof, either agree with the omitted parties upon the proper assessments and award the damages or assess such benefits, make such assessments for construction and make such additional assessments against the omitted lands and corporations, and award such damages as shall be just, and report the facts, together with such assessments and awards, to the court.
W.S. 41-9-247