Yellowstone River 2130 CFS @ Corwin Springs
Things are great on the Yellowstone River right now. Small to medium sized mayfly dries at the top of the river, nocturnal stones and hoppers in the middle to lower river, and hoppers for sure down low. The water clarity has been a bit variable as of late, but the fishing has been outstanding.
Jefferson River 405 CFS @ Twin Bridges
The Jefferson River is fishing quite well right now, and basically you can do well doing one thing- HOPPERS. Seriously, that is all you need. Small tan, or small yellow. This is closed at 2 PM, due to Hoot Owl, but the fish are there, and they are eating.
Madison River 984 CFS @ Cameron 1320 CFS below Ennis Dam
The Upper Madison seems to be very inconsistent right now. The fishing following the weather. Clouds are good, and the fish are eating everything from a Parachute Adams to Hoppers, and the streamer is getting some good fish as well. The Lower is under Hoot Owl (closed at 2 PM), but fishing well with crayfish, sculpins, micro mayfly nymphs and small purple lightning bugs.
Gallatin River 538 CFS @ Gallatin Gateway
Nocturnal stones, spruce moths, and caddis. The Gallatin is great right now, particularly with dries. The Pat's below the chubby is what every dude with a fly rod is chucking right now, so ditch that rig and throw the other stuff. You will be surprised, fish eat other flies than the chubby- generic.
Missouri River 4400 CFS below Holter Dam
The Missouri seems to be hit or miss right now, with decent trico fishing in the morning, and then some nymph eats to carry the day. Callibaetis can be an option, ants, beetles, hoppers, and still some caddis to be found. I would definitely fish early.