Colo. Rev. Stat. § 37-26-111
The refunding bonds and interest thereon shall be paid from annual assessments levied upon the real property within the district, and such real property shall be and remain liable to be assessed for such payments. Except when refunding bonds are issued for unpaid matured interest, no existing lien or liability created by an original issue of bonds shall be increased by issuing bonds to refund such original bonds. The board of directors of any district issuing refunding bonds shall take the same steps and adopt the same proceedings with respect to ordering and certifying such annual assessments, and county officers shall collect and enforce the same in the same manner as provided by law for the levy, certification, and collection of assessments for the payment of bonds refunded and interest thereon; except that amounts for principal and interest shall be ordered, certified, and collected separately.
C.R.S. § 37-26-111