This one has been difficult to identify. I can't spot any of the gill remnants characteristic of Perlidae, but the wing venation (Venation: The pattern in which the veins on the wings of an insect are arranged. It is usually one of the most useful identifying characteristics.) seems to point in that direction. I tried keying it out as Perlodidae but arrived at Isoperla, every western species of which has significantly smaller bodies than this one.
Edit: See forum comments for a likely correct identification.