Cell phone signal can be sketchy outside Kerrville proper.
As long as you have cell or internet, you could subscribe to water alerts from this station.
https://waterdata.usgs.gov/monitoring-location/USGS-08165300/#dataTypeId=continuous-00065-0&period=P7D
Well, I know of a guy who owns his own satellite network...
A scaled-down Starlink terminal configured with no-BS alarms could be implemented very inexpensively. I say that because NOAA Weather Radio sends out so many alerts that people ignore them as posted above.
So make a parallel system for high risk areas like this and wire the alarm output up to electrodes in the administrators bed if necessary! When that alarm is sounded, everyone is evacuated pronto - no questions asked.
Camp Mystic had 700 girls on site at over $4,000 each so don’t tell me they can’t afford it.
The problem is a system that doesn’t “cry wolf”.