This specimen resembled several others of around the same size and perhaps the same species, which were pretty common in my February sample from the upper Yakima. Unfortunately, I misplaced the specimen before I could get it under a microscope for a definitive ID.
While relatively rare in most of western Montana, it is common in several small streams along the east side of Flathead Lake and streams on the south side of the Flathead Indian Reservation.
This caddis is one of the most abundant caddisflies in temporary ponds of Glacier Park. The larvae build a round case of detritus and dead plant material that can get quite large.