seems like most of the guides in my area wont let you harvest from the river ( it's a good policy, rivers are harder to manage, i imagine)
i've gone a company hosted winter fly fishing trip to sarvis, where i know you can keep 2 trout.
its good, i'm pretty much a C&R purist as well on any river, and i dont really harvest fish unless its winter(crappie in the summer though!)
don't know why people would want to keep fish from the yampa, they are not tasty at all.