Test of Longhorn Dam Floodgate Warning Sirens Scheduled for September 15

AUSTIN – Austin Water will conduct a test of the floodgate warning sirens at Longhorn Dam on Tuesday, September 15, 2026, at 10 a.m. Residents and visitors in the surrounding area may hear the siren during the test. No emergency is occurring and no action is required from the public. The siren test will sound, one time, continuously for five minutes.

Pedestrian traffic will not be permitted on the Longhorn Dam section of sidewalk along Pleasant Valley Road during the siren test. There will be no impact to vehicle traffic and no impact to the Hike and Bike Trail or parkland. 

The siren test is part of Austin Water’s ongoing emergency preparedness program. The test at the dam will not change the position or status of the floodgates. It is intended to test the operation of the sirens and confirm the range and coverage of the sound. The test will provide personnel with an opportunity to monitor and verify sound levels at various points along Lady Bird Lake and the Colorado River. 

If this was not a test, in the event of an actual severe weather emergency requiring the release of storm runoff, the Longhorn Dam floodgate warning sirens would sound before the floodgates were opened. Increased flows, strong moving currents and unsafe water conditions would be present and recreational swimming, boating, kayaking and other water activities should be avoided.

“This test is an important part of maintaining our emergency preparedness and helps us reach the community quickly in an emergency,” said Stephanie Sue, Austin Water Assistant Director of Operations. “We’re grateful for the public’s understanding as we test the sirens and strengthen our systems and emergency communication tools.”

Modernization of the floodgate warning sirens began in 2026, with final installation completed in August 2026.

About Longhorn Dam

Austin Water manages the operation of Longhorn Dam for the City of Austin. Since taking over operations in 2018, Austin Water has conducted extensive maintenance and improvements to Longhorn Dam’s controls as well as the mechanical systems that move the various gates controlling water flow.

Visit austintexas.gov/longhorndam for more information about Longhorn Dam operations.