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.

Many camps in the Guadalupe river region are adjacent or are partially inside high-risk flood zones, according to maps from the Federal Emergency Management Agency.

When too much rain falls for the ground to absorb, it runs downhill, pulled by gravity into streams, creeks and rivers.