Deadly 2015 Utah flooding swept away families in small town, hikers in Zion National Park

Thirteen women and children were carried away in two vehicles near the Utah-Arizona border, and seven hikers were also swept away by rapid flash flooding. The 2015 flooding event killed 9 people.

Multiple strong thunderstorms with heavy rainfall moved through southwestern Utah on Sept. 14, 2015, creating significant and deadly flash flooding in Hildale, Utah, and Zion National Park that would claim the lives of 20 people, including 10 children. 

The two flash flooding events in the small polygamist community along the Utah-Arizona border and in one of the nation's famous national parks remain Utah's deadliest natural disasters. One death was also reported south of the border with Arizona. 

Flash flooding occurs when heavy rainfall, usually over a long period, moves over a dry land area. When water exceeds the ability of the ground to absorb it, flash flooding occurs. 

According to the National Weather Service's Salt Lake City office, heavy rainfall began in the early afternoon of Sept. 14, causing flash flooding in Short Creek in Hildale and then flooding Highway 59.


A second strong thunderstorm again moved over Hildale, causing more flooding. According to the NWS summary, 16 people were waiting for the flooding to subside and sought shelter in two vans when a large flood swept the vehicles down a channel.

After the floodwaters receded, the mud-covered and warped vehicles were found mangled in the flooding debris but without the people inside. Photos in the aftermath show search efforts in Colorado City, Arizona, and Hildale.

After an extensive search, local authorities said three people swept away were rescued, and 13 people inside those vehicles died. According to the NWS summary of the deadly flooding event, the victims included three women ages 27, 28 and 30. The remaining victims were all children; the youngest was just 4 years old.

Hiking group overcome by floodwaters in slot canyon

On the same day just one hour north of Hildale, a hiking group was lost when strong storms triggered flash flooding in Zion National Park. The water quickly overtook the slot canyon the group was exploring. Seven hikers between 51 and 59 years old were killed in the flash flood. 

On the morning of Sept. 14, the NWS office in Salt Lake City issued a moderate risk of flash flooding, including a higher risk for flash flooding in slot canyons that Zion is known for. 

The Los Angeles Times reports the hikers were all experienced with canyoneering training when they descended into Keyhole Canyon. According to the NWS, flooding in Keyhole Canyon happened quickly, and no one could reach higher ground.


In addition to the deadly cost of the flooding, the NWS estimated $750,000 in property damage to Washington County, Utah, as the water damaged roads, power lines and bridges. Flooding destroyed multiple cars, and homes were damaged during the floods. 

Flash flooding remains the second-deadliest type of extreme weather in the U.S., killing more people yearly than hurricanes, tornadoes and lightning. Only heat is deadlier than flash floods.