Civic
Longhorn Dam floodgate sirens get a test blast Tuesday morning.
A continuous five-minute siren at 10am Sep 15 — not an emergency; the dam sidewalk closes during the test.
September 8, 2026
Austin Water will test the floodgate warning sirens at Longhorn Dam on Tuesday, Sept. 15 at 10 a.m. The siren sounds once, continuously for five minutes. The city says no emergency is occurring and no public action is required.
Pedestrians cannot use the Longhorn Dam section of sidewalk along Pleasant Valley Road during the test. Vehicle traffic is not affected. The Hike and Bike Trail and parkland stay open. The test does not change the position or status of the floodgates. Austin Water says it is checking that the sirens work and how far the sound carries along Lady Bird Lake and the Colorado River.
If it were not a test, the sirens would sound before floodgates opened for a storm-runoff release. Modernization of the sirens finished in August 2026.
Sources
- Austin Water, Sept. 8, 2026 — Tuesday, Sept. 15, 2026, 10 a.m.; five-minute continuous test; not an emergency; dam sidewalk closed; floodgates unchanged
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