Floodwaters be contaminated with debris as well as high levels of bacteria, chemicals, waste and other pollutants, which can cause prolonged health risks, experts say.

Catastrophic flooding struck central Texas on Friday as the Guadalupe River surged by more than 20 to 26 feet within 90 minutes, causing widespread devastation and forcing mass evacuations in Texas Hill Country. At least 80 people have been killed in the floods while others remain missing or displaced and more than 850 people required rescuing.