Colo. Const. art. XXV

In addition to the powers now vested in the General Assembly of the State of Colorado, all power to regulate the facilities, service and rates and charges therefor, including facilities and service and rates and charges therefor within home rule cities and home rule towns, of every corporation, individual, or association of individuals, wheresoever situate or operating within the State of Colorado, whether within or without a home rule city or home rule town, as a public utility, as presently or as may hereafter be defined as a public utility by the laws of the State of Colorado, is hereby vested in such agency of the State of Colorado as the General Assembly shall by law designate.

Until such time as the General Assembly may otherwise designate, said authority shall be vested in the Public Utilities Commission of the State of Colorado; provided however, nothing herein shall affect the power of municipalities to exercise reasonable police and licensing powers, nor their power to grant franchises; and provided, further, that nothing herein shall be construed to apply to municipally owned utilities.