Tucked up above Devil's Gate Dam and below NASA's (or, as we like to think, Pasadena's) Jet Propulsion Lab, is a hiking/biking/dog walking heaven called Hahamongna Watershed Park. Most of the time you'd be hard pressed to find much water there. But after a weekend of rain, boy howdy! Devil's Gate Dam was doing it's job, and the watershed basin lived up to its purpose.
Where did they get that name, Hahamongna? Try saying it five times fast. I shouldn't complain. People have trouble pronouncing my name all the time.
Those river rocks I mentioned before--I believe they're manufactured in places like this.