Colorado Revised Statutes Title 42. Vehicles and Traffic § 42-4-901. Required position and method of turning

(a) Right turns. Both the approach for a right turn and a right turn shall be made as close as practicable to the right-hand curb or edge of the roadway.

(b) Left turns. The driver of a vehicle intending to turn left shall approach the turn in the extreme left-hand lane lawfully available to traffic moving in the direction of travel of such vehicle. Whenever practicable, the left turn shall be made to the left of the center of the intersection so as to leave the intersection or other location in the extreme left-hand lane lawfully available to traffic moving in the same direction as such vehicle on the roadway being entered.

(c) Two-way left-turn lanes. Where a special lane for making left turns by drivers proceeding in opposite directions has been indicated by official traffic control devices in the manner prescribed in the state traffic control manual, a left turn shall not be made from any other lane, and a vehicle shall not be driven in said special lane except when preparing for or making a left turn from or into the roadway or when preparing for or making a U-turn when otherwise permitted by law.