Wyo. Stat. § 15-7-409
The board of public utilities of any city or town engaged in the business of supplying water or electricity to its inhabitants which requires deposits to be made on water meters or electric meters furnished its customers, shall place all monies received from the deposits in a separate fund. The fund may be invested in securities as provided by law for trust funds of cities or towns. Any interest or income earned by or accruing to the fund, not otherwise pledged for the payment of general obligations or revenue bonds, may annually be transferred and paid into the general fund of the city or town. Any person who has made or makes a deposit on a water meter or electric meter is entitled only to the repayment of the principal amount of his deposit.
W.S. 15-7-409