This is the first of it's family I've seen, collected from a tiny, fishless stream in the Cascades. The three species of this genus all live in the Northwest and are predators that primarily eat stonefly nymphs Merritt R.W., Cummins, K.W., and Berg, M.B. (2019).
The spinner falls of this elegant species can be quite important to anglers across the West. Recent revisions have synonymized the Midwestern species Heptagenia diabasia that may be of some local importance.