Colo. Rev. Stat. § 32-11-205
Upon a vacancy occurring in the board by reason of a director's death, resignation, termination of office as a city council member, county commissioner, or executive officer, or failure to remain a professional engineer licensed by the state who is an elector of the district, and is not an officer or in the regular employment of any public body, as the case may be, in contravention of any provision in section 32-11-204(3) to (6), or for any other reason, the vacancy for the unexpired term of office of such director, upon the creation of such vacancy, shall be filled by the authority appointing him or her by the appointment forthwith of a successor director to serve for such unexpired term in the manner provided for such appointing authority in section 32-11-204 for regular appointments, except as otherwise provided in this section.
C.R.S. § 32-11-205