The famous nocturnal Hex hatch of the Midwest (and a few other lucky locations) stirs to the surface mythically large brown trout that only touch streamers for the rest of the year.
This one was surprisingly straightforward to identify. The lack of a sclerite at the base of the lateral hump narrows the field quite a bit, and the other options followed fairly obvious characteristics to Clostoeca, which only has one species, Clostoeca disjuncta.
Described by Frison, T.H. (1942) Descriptions, Records and Systematic Notes Concerning Western North American Stoneflies (Plecoptera). The Pan-Pacific Entomologist 18, 61–73.