How Mansfield Dam Made Lake Travis

Before the marinas and limestone coves, this was a deep Colorado River canyon near the old Marshall Ford crossing. LCRA and the U.S. Bureau of Reclamation built Mansfield Dam from 1937 to 1942. A hard 1938 flood changed the design: the dam grew taller so the new Lake Travis could hold floodwater as well as stored water.

That is why Lake Travis has two familiar lives. Its ordinary pool stores water and supports hydroelectric power and recreation. Above the full water-supply level is a flood pool designed to hold about 776,000 additional acre-feet while LCRA moves water through the system under federal operating rules.

The dam reduces Colorado River flood risk; it does not make every Austin-area flood a dam problem or prevent every flood. Rain below Mansfield Dam and water rushing through local creeks can still flood roads and neighborhoods. During a storm, local warnings and creek conditions matter alongside the lake level.