There is one TG listed for Izard County, 15401, on AWIN. I would imagine that they just use it some since there is only one TG. Usually if a dept uses AWIN full time they'll have some other TGs...it's possible they haven't been reported yet so if you're in the area, plug in the CCs for the local tower site and be in ID search mode (or wildcard on Whistler scanners) and see what you catch.
To answer the other question from Steven, I'm not sure what you mean by AWIN frequencies...you'll need the AWIN P25 system programmed in with that site included and then monitor the talkgroups you want to hear, such as Izard SO which is 15401. Sites, etc., are listed in the database AWIN listing on here.