The giant Salmonflies of the Western mountains are legendary for their proclivity to elicit consistent dry-fly action and ferocious strikes.
The tails on # 2 has keep me puzzled by being so dark and most Maccaffertium have pale yellow tails with reddish-brown articulations.
A good close up of the fore tarci would be helpful, John. Particularly the first few segments below the tibia.
OK I know now for sure the genus and species and they love that kind of water.
They are Stenacron I see the black spots in the mid area of the forewing towards the front edge. I will look at my specs to ad the species in a half hour. I spent all winter studying this group in great detail.