Nice catch, and some follow-up research shows that all of those WA schools are, indeed, in the OSAA now.

Of course, they're not noticed as much because they're all Oregon 1A (or basically 1B by WA standards, Trout Lake's school size is 12 kids!) and none of them have football or wrestling while Hermiston is a Washington 4A high school with 1500+ kids.

Looking at the map, though, the nearest OSAA 6A league is 3 hours away. Heck, the nearest 5A league is even farther. Meanwhile, the Tri-Cities are 45 minutes away and Spokane is 2 hours, 45 minutes.

I will admit that when I first heard of this years ago, it ruffled my feathers, but after taking a closer look it makes the most sense.