Drive I-10 west towards katy, i think the exit is 1463 / Pin Oak , it shouldbe just pass Katy Mills Mall. once u take that exit, pass thru Pin Oak and the next intersection should be a 4 way stop. there turn left (heading South), go under I-10 and like 50 yards up you will see a brigde. i park on the shoulder just before the bridge. the waterfalls are right there, you cant miss them.
also, if u drive over the bridge, u will see the neighborhood opening on the left hand side. theres another cool water fall there...
i hope this helps... one your on 1463, you cant miss them.