Early on the morning of Oct. 31, as waters rose to historic levels in Onion Creek, two of the flood gauges that officials rely on to monitor water levels weren't working. The flooding heavily damaged more than 600 homes and killed five.
One gauge was completely submerged by water, damaging the equipment – which isn't waterproof. But the other had malfunctioned before the flooding even began. And more than two weeks after the Halloween Floods, city and emergency officials still don't know why.
The gauges, which are managed by the U.S. Geological Survey (USGS), provide emergency responders with critical information during floods about how fast and how high flood waters are rising. In Austin, there are 130 flood gauges that measure water levels, rainfall and low-water crossings 24 hours a day.