Wyo. Stat. § 37-13-133
Upon completion of the conversion the public utility corporation shall present the governing body with its verified bill for conversion costs as computed pursuant to W.S. 37-13-129 or 37-13-131 of the statutes, but based upon the actual cost of constructing the underground facility rather than the estimated cost of the facility. In no event shall the bill for conversion cost presented by the public utility corporation exceed the amount of estimated conversion costs by the public utility corporation. If the conversion costs are less than the estimated conversion costs, each owner within the improvement district shall receive the benefit, prorated in such form and at such time or times as the governing body may determine to be fair and equitable. The bill of the public utility corporation shall be paid within thirty (30) days by the governing body from the improvement district funds or such other source as is properly designated by the governing body. In determining the actual cost of constructing the underground facility the public utility shall use its standard accounting procedures, such as the uniform system of accounts as defined by the federal communications commission, federal power commission or Wyoming public service commission in use at the time of the conversion.
W.S. 37-13-133