I looks like a toilet, but it's actually an early model wag bag, left behind like so many others. This model came with a strap for easy carrying back to the trailhead, but they were prone to leaking and quite heavy.
The new models look attractive along side the trail and they serve an important safety purpose. In a white-out, the smell can lead people back down the trail like bread crumbs.
Funny how there is such a variety of toilets in wilderness areas.
Edit: Answer is
here. Map here (approx. loc.)
