I'll second the Big Horn. Fished it every July for the last 4-5 years and a couple of other months in between. Was there in April and the water is low and very wadable in many sections near the boat launch and take outs if you don't have a boat. We stay at a lodge there and if you happen to be passing through and there's availability I highly recommend the place. Call David Couch at Tight Lines Lodge in St Xavier, don;'t have the number handy but worth a call.