The July 4 Guadalupe River Flood, Gauge by Gauge

Stream gauges along the upper portion of the river recorded the flood's deadly flow through the Texas Hill Country.

Words and visuals by Will Koeppen

What happened?

On July 1, 2025, the National Weather Service began predicting that remnants of Tropical Storm Barry could bring rain to the Texas Hill Country, a geographic area northwest of San Antonio. By the evening of July 3, forecasts that began as isolated showers had become urgent warnings of slow-moving convective storms that could drop up to 3 inches of rain an hour.

In the early hours of July 4th, the Guadalupe River swelled with deadly speed, killing 119 people in Kerr County.

The speed of the river's rise was staggering, even for a region known as Flash Flood Alley. On a normal day, the North and South Forks of the upper Guadalupe are shallow, tranquil streams, and the road along the river is just a few feet above the water. There are no stream gauges on the South Fork near Camp Mystic, but conditions on the North Fork are likely a good proxy. The river began rising there at 2 a.m., and by 5:30 a.m. it peaked at 20 feet above normal.

Downstream at Kerrville, the surge was just arriving, and the water climbed even faster, at one point rising 4 feet every 5 minutes. Typical flow volumes of the Guadalupe River in Kerrville are 10 to 50 cubic feet per second. During the July 4 floods, flows were estimated at more than 134,000 cubic feet per second. As many as 38,500 homes were flooded.

Where were people killed?

The most heartbreaking stories came out of the disaster at Camp Mystic, a Christian summer camp on the South Fork of the Guadalupe River upstream from Kerrville. Twenty-five young girls, two teenage counselors and the camp's director were killed. Campers closest to the river were evacuated to higher ground, but two cabins housing the youngest campers sat in a wide, flat area near the entrance of a tributary to the Guadalupe called Cypress Creek. Experts speculate that the speed of the water's rise and the hydraulics of the two converging waterways at night likely made rescue or escape impossible once the water reached a certain depth. The camp's director died while trying to shuttle campers from one of the affected cabins to safety.

Ninety-one other people died in Kerr County, primarily in Kerrville. Most were staying in family cabins, campgrounds or RV parks along the river when the water rose.

Sixteen people were killed in other Texas counties, particularly around Lake Travis on the Colorado River.

Why is it called Flash Flood Alley?

The geology of the area plays a major role. Sixty-six million years ago, during the Cretaceous Period, most of Texas, Oklahoma, and Kansas were covered by a large, shallow sea. As the coast receded, the Guadalupe River formed and began draining the broad, flat expanse of fossil-rich limestone, dolomite, and marl of the Edwards Plateau.

Twenty-five million years ago, the eastern side of Texas dropped 700 feet towards the Gulf of Mexico. The limestone plains broke along an arcing path known as the Balcones Fault, just north of San Antonio. All of the rivers in the area, including the Guadalupe, gained potential energy, incising their meandering channels as they cut downward through the faulted hills towards the coast.

The Texas Hill Country sits at a climatic transition between humid subtropical to the east and semi-arid to the west. When warm, moist air from the Gulf meets the cooler, dry air from the Great Plains over the hills, it can produce intense storms and heavy rain. When it does, water can't easily percolate into the shallow, rocky soil, and it instead sheets over the surface, quickly swelling the entrenched creeks and rivers.

What is the significance of Canyon Lake?

The lack of consistent water sources combined with a growing population has led to widespread dam construction across Texas, creating artificial reservoirs for recreation, drinking water and flood control. On the Guadalupe River, the first and only reservoir is Canyon Lake, formed by a dam built at the end of the fault zone where the river exits the hills.

After nearly three years of persistent drought, Canyon Lake was at 46% capacity on July 3, 2025, even lower than the 50% capacity limit imposed in 1964 to test the dam after it was constructed. The July 4 floods brought the lake up to 68% capacity within days, and the downstream gauges at Sattler and New Braunfels recorded only modest increases in water level.

What does the future hold?

The danger of flash floods on the Guadalupe River remains constant. The geology hasn't changed, and 15 to 20 camps still cluster along its banks.

In July 1987, a flash flood on the Guadalupe killed 10 teenage campers at the Pot O'Gold Ranch in Comfort, just downstream from Kerrville in Kendall County. Another 33 teens had to be rescued by helicopter as they clung to trees above the debris-filled water. Since then, there has been repeated talk about installing an early warning system along the Guadalupe in Kerr County.

Many neighboring counties already have such systems, but residents of Kerr County haven't been able to agree on what type of system to install or how much they should have to pay for it. A pilot program, financed by a $6 annual property tax increase, was canceled after only five years. In Kerr County meeting notes from June 27, 2016, Commissioner Buster Baldwin said, “The thought of our beautiful Kerr County having these damn sirens going off in the middle of night, I'm going to have to start drinking again to put up with y'all.” No sirens were ever built, and Baldwin died in 2022.

After the July 4 tragedy, and perhaps spurred by the media coverage of Camp Mystic, State Senator Paul Bettencourt introduced a bill that would require counties to build warning systems in flood-prone areas. The idea has at least verbal support from Gov. Greg Abbott.