The Start Of The Riverwalk

Behind the Municipal Auditorium is a ramp that leads down
to the San Antonio river. If you turn right and walk under
a bridge you'll see this scene.
It's the last 'wild' part of the waterway before the
Riverwalk begins, and a good place to start if you want to
see the whole thing.
A tripod and long exposure times are the trick to making
the flowing water look so smooth.

(Click to enlarge)