The Parks Department warns visitors with these photos and signs everywhere the area can change in the blink of an eye and it is deadly.  Sometimes rains miles away (without a drop even falling in this area) can fill the valley in a matter of a few minutes.  Getting out can be very difficult if you don't notice the early warning signs.  From points out by the falls it could take you five minutes to climb over the boulders, across the sand and gravel bars, and up the valley sides to safety.  Nature's fury... amazing.