sorry I cannot respond on Troutnut as my login is not working and
Jason is really busy right now so no time to fix the problem. No telling when I will get back on so here is my guess:
I suspect it is either a limnephilid or phryganeid, and, given the info you provided, I would go with the phryganeid. Tom Ames has a good discussion of the differences in emergence habits of both families in his recent caddisfly book. To summarize, most phryganeids emerge from the water surface, and limnephilids emerge on some type of structure.
Roger's color choice is good (although that specimen is quite faded from the live color) and there are alot of other limnephilids with that same color. [I don't think any Clistoronia occur in lakes big enough to maintain fish. They are usually in small, highly vegetated, shallow "ponds" often with some type of flowing water (stream, seepage flow, etc.) going through them.] In the Rockies phryganeids are quite common and highly fishable in ponds and lakes and several of the phryganeids are also quite pale. And all caddis immediately on emergence as you are seeing them, are very pale with poorly developed color patterns (teneral). Depending on the taxa and the weather it may take several hours before the final color patterns and darkening develop.
Hope that helps - I have had a long time interest in WY caddis so if you ever want to collect I will be more than happy to provide determinations - and the gear to collect if you are really interested.
Have a great day!
creno - on Troutnut
UPDATE: Per email from Dave on 11/1/2010:
Apparently C. magnifica occurs in fishable lakes and are sought by rainbows as larva, particularly under the ice.