Wyo. Stat. § 41-9-244
When the commissioners shall fail to certify to the county commissioners of the proper county, any one (1) or more drainage assessments for construction, reconstruction, enlargement, extension, improvement, or repair, against any lands in said district, at the proper time, they may certify the same to the county commissioners of the proper county at any time thereafter, whether in the same or any subsequent year, as an additional assessment roll of said district for the then current year, and upon receipt of such additional assessment roll by such county commissioners it shall be the duty of such commissioners to make a levy therefor and to certify the same to the county assessor in the manner hereinbefore provided, and it shall then be the duty of the county assessor to add the said levy to the tax roll for the then current calendar year.
W.S. 41-9-244