The data also highlights critical risks in other areas along the Guadalupe River in Kerr County, revealing more than twice as many Americans live in flood prone areas than FEMA's maps show.

Flash floods surged through in the middle of the night, but many local officials appeared unaware of the unfolding catastrophe, initially leaving people near the river on their own.

Two days before flash floods on the Guadalupe River in Texas killed dozens of campers at a Christian girls summer camp, a state inspector approved operations, noting there was a written plan for responding to natural disasters.