I did an internet search on "veterinary surgeons Iowa" and came up with several private practices. There's also this site where you can supposedly search for board certified vet specialists, but I admit I can't figure out how to search for a surgeon in Iowa there.
Veterinary Specialist Directory - Find Veterinary Specialist - VetSpecialists.com
I used a site like that when I bought a puppy out of state and wanted to have heart and eye exams done by board certified specialists before flying home with her.
When I looked for vet ortho surgeons for TPLO surgery, I asked dog people I knew who they had used and had good experiences with. If you have no access to people like that, you might call some breeders, trainers, and rescue groups that deal with large dogs in your area. Some will brush you off, but you might find some who will be helpful. Don't know how far you can travel.
P.S. Saw LeoRose's post, and I agree - didn't anyone at Iowa State give you names of private vet surgeons who could do the surgery? Maybe call them and ask specifically for references. Hard to believe they want you to wait with a dog in pain until they can do it, but I admit my experiences with university vets here in Colorado have all been discouraging, although I know people who swear by them.