They are listed in RadioReference without a NAC:
Colorado Mutual Aid (Colorado) Scanner Frequencies and Radio Frequency Reference
I program them in with a NAC Search so I receive all the radio traffic no matter what NAC code is used. I don't believe I have ever heard anything on these mutual aid channels.
I am not sure what the origins of those 700 MHz frequencies are other than it probably being something that was nationally listed for a very short period back when national mutual aid frequencies were included on that page. They are not listed in either the national or state Field Operations Guides for interoperable communications or by CCNC.
As far as I can tell, it is likely some residual stuff from the early days of 700 MHz when everyone was drafting all sorts of plans for the band before things got settled and all of those frequencies got allocated to FirstNet. It seems like an FCC license was required to use those frequencies, most of which were granted around 2006 to a grand total of 17 entities, but no one in Colorado had ever applied for a license for those frequencies. Almost everyone who licensed those frequencies ended up cancelling the license or letting it expire.
It seems like those frequencies were likely replaced with the new 700 MHz itinerant frequencies that are listed in NIFOG and the national database. One may notice that the new itinerant frequencies are offset from the old frequencies so that they fit into the current 700 MHz narrowband allocation.
They should probably be removed from the database at this point considering that all of the other national stuff got floated up to the Nationwide database more than a decade ago, and I am not aware of anyone who has heard them being used in the state.
