Successful reception of the major networks will require an outdoor antenna. It would be helpful to see the 25' AGL TV Fool Report. The terrain of Delta, CO appears to be relatively flat within the City limits. So I'll be pleasantly surprised if there is a significant difference between your current TVFR and a report based on 25' AGL.
The traditional solution for you would be a deep fringe antenna, preamp and rotator mounted 5 to 12' above the roof peak. Here is a list of equipment that would fit the situation your working with;
Winegard HD7698P
Antennas Direct CPA-18
NTE U-106
NTE TB105
Depending on your roof and general building construction, there are several ways to mount a mast. Here are a variety of mounting options;
http://www.3starinc.com/antenna_mounts_masts.html
Other vendors to consider:
http://www.amazon.com
http://http://www.solidsignal.com/
http://starkelectronics.com/
http://www.channelmasterstore.com/
http://www.warrenelectronics.com/