Wyo. Stat. § 21-13-709: How bonds to mature.

The various annual maturities shall commence not later than the third year after the date of the bonds. All bonds shall mature serially, at the option of the board of trustees, in substantially equal annual installments of principal, or upon an amortization plan for the bonds of said series, or upon an amortization plan for the proposed bonds and all outstanding bonds of the district, or in any other manner as the board may determine.