Jefferson River 1340 CFS @ Twin Bridges
The Jefferson River is fishing quite well right now, and it probably won't be a long season here this year. Sculpins and crayfish are great lead flies for nymphing, trailed by Psycho May, PT's, and Sally nymphs for most of the day. Caddis are thick in the evenings.
Madison River 1230 CFS @ Cameron 1530 CFS below Ennis Dam
The Lower Madison is still fishing well, but it is getting a little warm, and the bikini hatch as begun in earnest. Still a good option, but with everything else that is fishing well, probably a better experience going elsewhere. Crayfish, caddis, and worms are still catching fish. There is a lot going on above Ennis- Salmon Flies, Golden Stones, PMD's, Sallies, and caddis are all going strong right now. The Upper has a great flow, and is fishing very well.
Gallatin River 1430 CFS @ Gallatin Gateway
The Gallatin River has finally come into shape, and is actually perfect right now. All the hatches are happening, and the fish are eating well. The river is still a big high, so be careful wading. Look for all the hatches listed above on the Gallatin as well.
Missouri River 4280 CFS below Holter Dam
Things are still going strong on the Missouri River right now. The river is slowly coming down, and the PMD's, Sallies, and caddis are all hatching. The PMD dry fly fishing is some of the best of the season on the Mo.
Yellowstone River 6140 CFS @ Corwin Springs
The Yellowstone River has come around as of last week, and there are Salmon Flies, and Golden Stones hatching around Emigrant and above. The PMD's are thicker than I have seen in recent years, and the Little Yellow Sallies and several types of caddis are around as well. The fishing on the Yellowstone is as good as it gets right now.