Okay, I perhaps it's time for some clues. Although this caddisfly is not well-known, it has been reported from WA, inhabits stillwaters, and emerges in October. It is of the same family (and closely resembles) a caddisfly which is well-known, also emerges in October, but inhabits rivers rather than stillwaters.
Giant Orange Sedge is one of the common names for the (quite similar) river-inhabiting caddisfly mentioned in post #2 of this thread. However, its stillwater-inhabiting counterpart does not have any common name of which I am aware.
I have seen what may be this species hatching out of Rattlesnake Lake. I previously thought they were October caddis, but now I know I must've been wrong. I done learnt me sumthin. Way to go on the ID, Patrick.