Colo. Rev. Stat. § 39-1-101
The general assembly declares that its purpose in enacting articles 1 to 13 of this title is to exercise the authority granted in section 3 of article X of the state constitution wherein it is provided, among other things, that "the actual value of all real and personal property not exempt from taxation under this article shall be determined under general laws, which shall prescribe such methods and regulations as shall secure just and equalized valuations for assessment of all real and personal property not exempt from taxation under this article". It further declares that it intends to fix the percentage of such determined actual value at which all such property shall be assessed for taxation. It further declares that the actual value of certain classes of real property may not be able to be determined after appropriate consideration of the three approaches to value; therefore, it is incumbent upon the general assembly to provide for a means to determine the actual value of such taxable property, and, to effect this result, the general assembly hereby finds and declares that, when appropriate consideration of the three approaches to value fails to derive an actual value for such property, the actual value of such property shall be determined by comparison of the surface use of such property to property with a similar surface use. It further declares that the actual value of nonproducing oil, gas, and oil and gas mineral interests shall be determined by the income approach capitalizing annual net rental income at an appropriate market rate. To these ends, the provisions of said articles shall be strictly construed.
C.R.S. § 39-1-101