A canyon just west of Wild Horse Mesa looks like a promising route downward
Date: May 27, 2009, 14h44
Peering through the wire, I see a large, dry concrete reservoir
Though dry today, this would have held a lot of water. I've heard that this reservoir supplied the town of Kelso with water and perhaps the passing steam-engine trains as well. In this dry country, it would have made a great swimming hole too!