Olmos Dam

About Olmos Dam

The primary purpose of Olmos Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by City Of San Antonio (local government). It impounds the Olmos Creek near San Antonio.

The dam stands 58 feet tall and stretches 1,941 feet across, has a maximum storage capacity of 21,970 acre-feet, and collects water from a drainage area of 32 square miles. Completed in 1926, the structure is well-established, with more than 75 years of service.

This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. An emergency action plan is in place for this dam. The most recent inspection on record was 03/08/2018. That was 8 years ago, which is on the longer end for a high-hazard structure.

At 58 feet, this dam is taller than 95% of all dams in the United States.

Living Downstream

If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Texas dam safety program can provide more specific information about emergency planning for this structure.

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