An early warning alarm system had been proposed for years previously but was deemed too expensive. Kerr County also didn't issue evacuation orders where the cops go around will loudhailers trying to wake people up - apparently they were concerned that evacuating cars would get trapped in the floods. The first alert was at 1:14am the last at 4:03am and they were sent by mobile phone - so if your phone was off or had no signal or didn't wake you....
The state is now saying that they will pay for flood sirens,
https://edition.cnn.com/2025/07/07/us/texas-floods-warning-system-invs
Also, they have a problem with stupid people:
It also seems that a lot of the cabins in Camp Mystic were built on the flood plain most likely to flood and no-one seems to have noticed whether they should be there as they had been there for 50+ years.