C.R.S. § 40-6-112

(1) The commission, at any time upon notice to the public utility affected, and after opportunity to be heard as provided in the case of complaints, may rescind, alter, or amend any decision made by it. Any decision rescinding, altering, or amending a prior decision, when served upon the public utility affected, shall have the same effect as original decisions. (2) In all collateral actions or proceedings, the decisions of the commission which have become final shall be conclusive.