C.R.S. § 40-4-112

The commission has power, after hearing, to require any or all public utilities to carry a proper and adequate depreciation account in accordance with such rules, regulations, and forms of accounts as the commission may prescribe. The commission, from time to time, may determine and by order fix the proper and adequate rates of depreciation of the several classes of property of each public utility, and each public utility shall conform its depreciation accounts to the rates so determined.