Colo. Rev. Stat. § 32-7-140
For the purpose of providing public surface transportation, a service authority shall have, insofar as consistent with this article, any additional special powers applicable to the provision of that specific service as provided by article 9 of this title. The mill levy limitation for ad valorem taxes imposed by said article 9 shall be applicable to the service of public surface transportation when such service is provided by a service authority. Any municipality may plan or operate a public surface transportation system, and any county or municipality may contract with a service authority for the planning or operation of such a system. In addition, any county may plan and operate such a system if such plan is made in coordination with, or is made by, a regional transportation district or a service authority.
C.R.S. § 32-7-140