Hi Rob,

From the photo, I can not say what type of ants you're dealing with.  I would need a very clear close up of an ant to be able to have a chance to identify them (or you could bring/send a sample to the Extension office is Castle Rock).

One of the more common types of ants you would find in fields and open areas is the Harvester ant; more information about these can be found here: https://webdoc.agsci.colostate.edu/bspm/arthropodsofcolorado/Harvester-Ants.pdf

Field ants (Formica ants) are also common, particularly in yards. 

This fact sheet about nuisance ants in homes describes some other common types along with control measures that you may want to consider: https://extension.colostate.edu/topic-areas/insects/ants-in-the-home-5-518/

I hope this is helpful.

Cordially,

John