Wyo. Stat. § 37-3-119
In determining just and reasonable rates under this chapter for an interstate electric public utility where a portion of system costs are apportioned to Wyoming ratepayers, the public service commission shall exclude any system costs from rate determinations that do not have a benefit to ratepayers in Wyoming. Costs that may be excluded include the proportional costs associated with facilities that are built or operated primarily for the benefit of other states or entities outside of Wyoming. The public service commission may approve a reduced apportionment of costs to Wyoming ratepayers to the extent that system costs are used to serve Wyoming ratepayers but which relate to facilities that were built at a higher cost than potential alternative sources of electricity, as determined by the commission, because those alternative sources of electricity may not have met electricity service requirements established by other states or entities outside of Wyoming.
W.S. 37-3-119