Flows are a bit lower, 714cfs, than the long term average, 1040cfs, as they're filling up Hebgen Lake which is 94% full. The river is clear coming out of the dam and then Cabin and Beaver Creeks are dumping in some dirt.
Fishing has been good between the lakes and best in the mornings with small nymphs. Pheasant tails, pearl lightning bugs and brown three dollar dips in #16, #18 dropped off a rubber legs #6 or red San Juan worms have been the best combo.
The best reports are coming from Reynolds and 3$ bridge. The water is off color and with 18" of visibility. Some baetis and caddis are hatching and a few fish are rising. Nymphing has produced the most fish, but searching around with a purple haze will bring them up. If you want to try for a big brown put on a olive and white double bunny.
The river is dirty below Sage and Taylor's Fork. Nymphing has been decent above there and inside Yellowstone. Larger prince nymphs, rubber legs, and red San Juan worms are the go to flies for now.
The lake is getting better as the weather has warmed up. Lots of chironomids hatching and the fish are rising. For dries use chironomid cripple or a parachute adams #14. The best action is ice cream cones and big black zebra midges under indicators. Stripping leeches and buggers has been slow, but there has been a little action on black and olive.
This has been the place to go. The water is in great shape and the fishing has also been great. PMD's and white Miller caddis #16 are hatching in the upper river, especially at Fountain Flats. Stoneflies and caddis can be found lower on the river in Firehole Canyon. Swinging soft hackles has been very productive. The best two are partridge and green #14, and hare's ear soft hackle #14.
We aren't getting many reports about the Madison in Yellowstone. Hatches are getting better and you can look for the fishing to begin to pick up on this stretch in the next week. PMD's, caddis, and some stoneflies are some go to flies to take with you.