Speaking of the Okanogan (the region, not the lake), one of my absolute favorite patterns for the Callibaetis hatches at Lake Chopaka is what I've long called the Chopaka Emerger. A friend of a friend showed me the original pattern which was given to him by an "old timer at Lake Chopaka". After tying and fishing (and, bit-by-bit, modifying it) over many years, it reached what I consider its final form. Tied on a size 14 dry fly hook and fished on the surface it is highly effective during the hatch of Callibaetis mayflies. Although it bears a strong resemblance to many other mayfly emerger patterns, I still think of it as the "Chopaka Emerger"