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 page refers to the small American River that flows eastward from headwaters near Mount Ranier in Washington to join the Naches, Yakima, and Columbia rivers.
Although it is known to have some trout, I have not had good luck fishing here.