The climate of Central Texas is sub-humid, it’s not unusual for most river beds to go dry during the hot season. When rain falls, flash flood warnings are frequent, rivers and creeks come back to life for a few hours, sometimes flooding over roads and trails, before drying up until the next downpour.
Hamilton pool, a nice preserve North West of Austin, is fed by the Hamilton creek, falling into a pool and then running off to the Pedernales river. After a heavy downpour, the waterfall comes back to life and is magnificent.
The Hill Country, the region surrounding Austin, is on a porous limestone formation. Water runs down into the Edwards aquifer. That is the balance of water there.
Here’s Hamiton pool and its waterfall, alive.