This actually isn't a waterbody of any sort, though it does look like it on aerial imagery-- that's part of why on the ground verification is important for OSM. This is actually a large black tarp with tires placed on it. It collects water during rainfall events and feeds it into the concrete tank/reservoir immediately south of the collector. The water is stored until the drier parts of the year and then fed into livestock troughs/ponds nearby. This particular collector is maintained by the BLM - St. George Field Office. I'm going to revert this change tomorrow. Glad to have another mapper in the area, just please make sure to double check what you see on aerial.