Last time I was at that spring, it was about 3 years ago. The actual soaking pool, if it is still there, was about 200 yards uphill from the trough you found. (sounds like you were close but just missed it. Or rather, you didn't miss anything- see below.) With the perfect soaking temperature, and panoramic view of the Snake River valley and the rocky crags of the Bennet Mountain hills, it would have been one of the best hot springs I had ever been to.

But for one nightmarish problem- it was infested with these red parasitic mites!! Nearly microscopic, nonetheless each one of these delivered a series of itchy welts, and I came out of the spring looking and feeling like I had chicken pox. Worst hot spring experience EVER!!!

Love your site. I'm a big rock hound too. Hope to make it to Dismal Swamp (if it's still possible) this fall.