On July 30, 2016 at about 3:40pm, Zion dispatch received a cell phone call from a group of three reporting that they were in distress on the East Rim Trail. The group reported that they were out of water and afraid that they would not be able to make it back to the trailhead. The group was calling from Stave Spring (which was dry at the time). They had the small rectangular souvenir park map that was given to them at the entrance station. Based off this limited detail, not to scale map they had planned to hike from the East Entrance to Angels Landing. If they had done a small amount of research or had a map with mileages or topo lines they would have recognized that it was impractical for them to hike from the East Rim trailhead to Angels Landing and back in one day. (This is over 24 miles with about 2,300+ feet in elevation change multiple times.)
Rangers were able to make contact via cell phone and directed them to walk to the Stave Spring trailhead where two Wilderness Rangers met them in a vehicle and gave them a ride back to their car at the East Rim trailhead.
Lessons learned: Do some research or at least ask a question or two. Use a map with mileages and contour lines if you are embarking on a longer trail. Bring lots of water; don't expect springs to be running.