Wyo. Stat. § 41-3-936
The priority of appropriation of underground water obtained prior to April 1, 1947, shall date from time of completion of the well. The priority of appropriation of underground water obtained subsequent to April 1, 1947, and prior to March 1, 1958, shall date from the filing of registration in the state engineer's office. The priority of appropriation of underground water obtained on or subsequent to March 1, 1958, shall date from the filing of the application for permit in the state engineer's office. Priority of appropriation of underground water for stock or domestic purposes, as defined in W.S. 41-3-907, shall date from the time of completion of the well if properly registered with the state engineer prior to December 31, 1972. If registered with the state engineer subsequent to December 31, 1972, the priority shall date from the filing or registration in the state engineer's office.
W.S. 41-3-936