This week marks the 100-year anniversary of one of San Antonio’s worst floods

The River Walk owes its existence to the 1921 flood

Photograph shows view looking north, from river bridge, toward intersection with College Street. Texas State Bank and Trust Company on ground floor of the Grayburg Building on left. (UTSA Special Collections)

SAN ANTONIO – Flooding happens in San Antonio on an annual basis. But, there’s a handful of floods that have truly rewritten the history books. The ‘Flood of ‘98′ and the flood of 1913 stand out. It’s the flood of 1921, however, that truly shaped San Antonio’s future and altered how the city would deal with heavy rain in the future.


As you might have guessed, this event had a tropical connection. On Sept. 7, well south of San Antonio, a Category 1 hurricane made landfall south of Tampico, Mexico. The energy from the tropical system raced northward. By Sept. 8, rainfall in San Antonio had begun. The heaviest rainfall fell on Sept. 9.

Surface weather analysis of the second hurricane of the 1921 Atlantic hurricane season on September 7, 1921. This shows the hurricane as it makes landfall near Tampico, Mexico.


According to the U.S. Geological Survey, San Antonio first recorded rain on the morning of Sept. 8, 1921. In total, 0.54″ was reported that day. The following day, 5.38″ fell and initiated the flooding. Sept. 10 would bring an additional 1.46″. The grand total was 7.38″. You might be thinking that doesn’t seem that bad. Keep in mind that San Antonio was a growing city without any flood control. Until this flood, that is....


San Antonio suffered major damage from the flood waters. Buildings were damaged and debris littered the city. More than 50 people lost their lives in San Antonio, while property worth more than $3,000,000 was destroyed. Water as deep as 10 feet in the downtown area flooded buildings and homes, according to the USGS. It should be noted, however, that San Antonio was spared the worst of the storm. Three-day rainfall estimates of nearly 40″ were reported in nearby Williamson County. In total, the storm resulted in 224 deaths and property damage reached to more than $10,000,00. Had the higher rainfall totals been centered over San Antonio, the disaster would have been much worse.

Flood waters left behind significant damage through San Antonio business section
Photograph shows debris, including overturned automobile, in front yard of St. Mary's Church rectory. Side of church visible on left. Taken after flood of September 10, 1921.

Olmos Dam and the River Walk

The flood spurred change. City planners realized that flood control was needed to prevent future tragedies. So plans to build Olmos Dam were started. A bypass channel through downtown was also designed to protect against flooding along the San Antonio River. Plans included cementing over and covering the storm sewer. Famously, architect Robert Hugman proposed putting businesses along the channel instead of paving over the water way. He would eventually move forward with his idea, creating what is now the world-famous River Walk. The two projects proved invaluable during subsequent flood events.

The Olmos Dam after its completion in 1927.

About the Author:

Justin Horne is a meteorologist and reporter for KSAT 12 News. When severe weather rolls through, Justin will hop in the KSAT 12 Storm Chaser to safely bring you the latest weather conditions from across South Texas. On top of delivering an accurate forecast, Justin often reports on one of his favorite topics: Texas history.