Wyo. Stat. § 15-7-107
A tax to be fixed by ordinance shall be levied each year to pay the interest on the bonds and to create a sinking fund for their redemption. The money that may be on hand at any time belonging to the sinking fund, until there are bonds redeemable, may be loaned or invested by the governing body in any public securities of the state, any subdivision thereof, or of the United States, and the interest that accrues shall be added to the sinking fund. If at any time after ten (10) years from the issue of the bonds the sum in the sinking fund equals or exceeds five hundred dollars ($500.00), and from time to time thereafter when it accrues, the city or town treasurer shall publish a notice in a newspaper in the city or town that, thirty (30) days from the date of the notice, he will redeem the amount of bonds then payable, giving their number and giving preference to the oldest issue. If at the expiration of thirty (30) days the holder of those bonds fails to present them for payment, the interest thereon ceases, but the treasurer shall redeem them on presentation. A copy of the notice shall be sent to the bank designated as the place of payment of the interest on the bonds.
W.S. 15-7-107