Colo. Rev. Stat. § 31-10-905
If the ballots to be furnished to any election judge are not delivered by 8 p.m. on the Monday before election day or if after delivery they are destroyed or stolen, the clerk shall cause other ballots to be prepared, as nearly in the form prescribed as practicable, with the word "substitute" printed in brackets immediately under the facsimile signature of the clerk. Upon receipt of ballots thus prepared, accompanied by a written and sworn statement of the clerk that the same have been so prepared and furnished by him and that the original ballots have so failed to be received or have been destroyed or stolen, the election judges shall cause the ballots so substituted to be used at the election. If from any cause none of the official ballots or substitute ballots prepared by the clerk are ready for distribution at any polling place or if the supply of ballots is exhausted before the polls are closed, unofficial ballots, printed or written, made as nearly as possible in the form of the official ballots, may be used until substitutes prepared by the clerk are printed and delivered.
C.R.S. § 31-10-905
This section is similar to former § 31-10-511 as it existed prior to 1975.