Wyo. Stat. § 41-9-250
Any owner of land, or any interest in land, within a drainage district, who claims that his land in said district is exempt from liability for, or lien of any assessment for construction or repairs, or any additional assessment by said commissioners levied against the same whether said assessments be the first or any subsequent assessment or questions the legality of such assessment, may at any time, on ten (10) days notice, or order to show cause, be brought before the court having jurisdiction and required to show cause why said land should not be bound by all drainage district assessments in any report or reports of the commissioners of said district assessed against the same. The presumption shall be in favor of the regularity of such assessments, and they shall stand as valid assessments unless the owner of such land, or some interest therein shall show that said assessment is inequitable, or is void because the lands were not subject to assessment in the first instance.
W.S. 41-9-250