Wyo. Stat. § 41-4-312
Should any person, corporation or association of persons owning any irrigation works, or claiming any interest in the stream or streams involved in the adjudication, desire to contest any of the rights of the persons, corporations or associations who have submitted their evidence to the superintendent as aforesaid; such persons, corporations or associations shall, within fifteen (15) days after the testimony so taken shall have been opened to public inspection, in writing, notify the superintendent of the water division in which is located said irrigation works or stream or streams, stating with reasonable certainty the grounds of their proposed contest, which statement shall be verified by the affidavit of the contestant, his agent or attorney, and the said division superintendent shall notify the said contestant and the person, corporation or association whose rights are contested, to appear before him at such convenient place as the superintendent shall designate in said notice.
W.S. 41-4-312