Water guzzler seen from Dead Horse Point State Park... 20081007_8168
From the overlook at the visitors' center of Dead Horse Point State Park I spotted some interesting signs of human activity far below on the canyon topography (identified by notes on photo). Two years later I explored the road, seeing the noted features up close.
Dennis Udink's comment defines the structure on the left as a water guzzler. They are used to collect rain water and store it for the benefit of wildlife, as seen in these pictures on the web site of a company that makes them. Perhaps this one serves the Bighorn sheep that live here.
This article describes how water guzzlers are used to compensate for shortages of water.
Some research on this topic introduced me to the terms "water catchment" and "rainwater harvesting."