Wyo. Stat. § 18-12-141
A district shall not acquire any new improvement or facility or provide any new service that was not originally described in the petition for formation of the district unless the new improvement, facility or service is authorized by this act, approved by the board of county commissioners of the county in which the district is situated and approved by a majority of the qualified voters of the district. Upon approval of the board of county commissioners and by resolution of its board, a district may submit to its qualified voters, by mail ballot election pursuant to W.S. 22-29-116 or concurrently with any other district election, the proposition of acquiring any new improvement or facility or providing any new service authorized under this act.
W.S. 18-12-141