Colo. Rev. Stat. § 37-47-133
Except for the issuance of refunding bonds or other funding or refunding of obligations which does not increase the net indebtedness of the district or any subdistrict so proceeding, no indebtedness shall be incurred by the issuance of general obligation bonds of any subdistrict or by any contract by which the district or a subdistrict agrees to repay as general obligations or other obligations constituting a "general obligation debt by loan in any form", as such term is used in section 6 of article XI of the state constitution, of the district or subdistrict, respectively, to the federal government, any political subdivision, or any person over a term not limited to the then current fiscal year any project costs advanced thereby under any contract for the acquisition or improvement of the facilities or any interest therein, or for any project, advanced by the issuance of securities of such a political subdivision or person to defray any cost of the project or of the facilities or an interest therein thereby acquired and becoming a part of the facilities of the district or subdistrict, or otherwise advanced, unless a proposal of issuing the subdistrict's general obligation bonds or of incurring an indebtedness by the district or subdistrict by making such a contract is submitted to the electors of the district or subdistrict, as the case may be, and is approved by a majority of such electors voting on the proposal at an election held for that purpose in accordance with this article and with all laws amendatory thereof and supplemental thereto.
C.R.S. § 37-47-133