The weeks leading up to May 24, 2015 were very stormy across Central Texas.
For the first 2 to 3 weeks of May, many areas across Central Texas were 2 to 4 inches above normal rainfall. These well-above normal rainfall totals set the precedent that any additional rain that fell would almost immediately runoff into creeks, streams, and rivers rather than soaking into the ground.
By Saturday, May 23, a storm system setup across the region that dropped widespread 6-8 inches fell across Bandera, Kerr, Kendall, Blanco and far west portions of Comal and Hays counties with a max of 10 to 13 inches of rain across southern Blanco and extreme NE Kendall counties. Most of this rain fell Saturday night and Sunday morning.
The watershed that this rain fell over feeds into the Blanco River, which flows from southern Blanco County into Hays County. Towns like Wimberley and San Marcos are located downstream from where the heaviest rain fell, but experienced the worst of the river flooding.
The Fischer Store Road bridge over the Blanco River just west of Wimberley was completely destroyed from the flood waters and has since been rebuilt.
The Blanco River, down stream from the bridge, at Wimberley reached a record crest. The gauge failed at 40 feet and the USGS later estimated the crest at 44.9 feet with 175,000 cfs. This height was more than 10 feet over the previous record height of 33.3 feet from 1929.
A historic statistic from the National Weather Service indicates that the Blanco River at Wimberley rose 5 feet every 15 minutes from 10:45 to 11:45pm. This means the river rose 20 feet in just an hour’s time.
This wall of water swept away entire homes and full size cypress trees. Debris struck multiple homes that were able to withstand the torrent of water.
The most tragic story of all was a home where nine people and a dog were vacationing in was swept away by the rapid rise in water. All but one person and the dog survived. Two children were never found. A 29 year-old man was killed when his car was washed off the road. And a 74 year-old man drowned when he was swept off his roof waiting to be rescued. In total, 13 people lost their lives due to the floods.
As, what has been described as, a “tidal wave” of water continued to rush downstream towards San Marcos, debris from destroyed homes and large trees continued to was away more homes and businesses.
For the first time ever, Interstate 35 was shut down due to water over the highway over the Blanco River. Water also overtopped and closed Highway 80 just east of I-35.
In total, 1515 structures were impacted with 321 houses destroyed and an additional 376 receiving major damage according to assessments along the Blanco River in Hays County. It is estimated that there were $100 million (2015 dollars) in insured losses for this flash flood.