Colo. Rev. Stat. § 31-25-611.5
In order to defray all or any portion of the costs of the improvements or services provided by the district, the board may establish special improvement districts within the boundaries of the district in accordance with part 5 of this article. Such special improvement districts may be established whenever the board determines that property in the district will be especially benefitted by such improvements or services. The method of creating special improvement districts, making the improvements or providing the services, and assessing the costs thereof shall be as provided in part 5 of this article. However, the electors eligible to vote on any question under this section shall either be electors of the district or electors within the local improvement district, as determined by the board. In addition, the board shall perform the duties of the governing body set forth in part 5 of this article, and the secretary of the district shall perform the duties of the clerk set forth in part 5 of this article. The improvements that the special improvement district may construct and the services that the special improvement district may provide shall be the improvements and services that the district may provide pursuant to this part 6.
C.R.S. § 31-25-611.5