Colo. Rev. Stat. § 8-20-211.5
Throughout the state of Colorado, all visible containers and all devices for drawing motor fuel blends containing class I fuel products and at least two percent by volume of alcohol from underground containers at filling stations, garages, or other places where such products are sold or offered for sale shall be stamped or labeled in a visible place with information indicating the presence of alcohol in the motor fuel blend. If the volume of ethanol exceeds ten percent, or if the volume of methanol exceeds two percent, the stamp or label shall state the exact percentage. Such information shall appear on the front of the pump in a position clear and conspicuous to the driver's position, in at least one-half inch block letters, with information that identifies the maximum percentage by volume to the nearest whole percent of ethanol or of methanol or methanol with cosolvents.
C.R.S. § 8-20-211.5