Colo. Const. art. XI, § 6

(1) No political subdivision of the state shall contract any general obligation debt by loan in any form, whether individually or by contract pursuant to article XIV, section 18 (2)(a) of this constitution except by adoption of a legislative measure which shall be irrepealable until the indebtedness therein provided for shall have been fully paid or discharged, specifying the purposes to which the funds to be raised shall be applied and providing for the levy of a tax which together with such other revenue, assets, or funds as may be pledged shall be sufficient to pay the interest and principal of such debt. Except as may be otherwise provided by the charter of a home rule city and county, city, or town for debt incurred by such city and county, city, or town, no such debt shall be created unless the question of incurring the same be submitted to and approved by a majority of the qualified taxpaying electors voting thereon, as the term "qualified taxpaying elector" shall be defined by statute.

(2) Except as may be otherwise provided by the charter of a home rule city and county, city, or town, the general assembly shall establish by statute limitations on the authority of any political subdivision to incur general obligation indebtedness in any form whether individually or by contract pursuant to article XIV, section 18 (2)(a) of this constitution.

(3) Debts contracted by a home rule city and county, city, or town, statutory city or town or service authority for the purposes of supplying water shall be excepted from the operation of this section.