Colo. Rev. Stat. § 38-6-209
After the report of the commissioners is filed with the clerk of the court, the court shall fix a time for the consideration of said report, and the petitioner shall give written notice to the defendants and all other persons who are the owners of property mentioned in said report, whether damaged, appropriated, condemned, or assessed special benefits, of the matters contained in said report and of the time so fixed by the court for the consideration thereof. The notice shall be served in like manner as is provided by the laws of this state for the service of summons in civil actions, except as otherwise provided in this section. Said persons shall be served at least ten days before the time fixed for the consideration of the report by the court. In case any defendant or owner of any property damaged, appropriated, condemned, or assessed special benefits does not reside in the state or is a foreign corporation or in case the attorney for said petitioner files an affidavit that he has endeavored to find such person for the purpose of causing said person to be notified and that after reasonable effort he has been unable to find said person in the state, the petitioner may cause to be published a notice, of the matters affecting such person contained in said report and of the time fixed for the consideration thereof, for three successive times in some daily or weekly newspaper published in said judicial district. Said publication shall be in lieu of personal service of said notice on all such persons.
C.R.S. § 38-6-209