As noted, there are several states, particularly in Colorado, where the government has seen fit to make it against the law to capture or use the rain water that falls on your own property. You can't even use your water twice, like using grey water to irrigate your orchard. Verboten.
Putting this in the best possible light, if they don't do that in Colorado and similar states, the Colorado river could dry up and Los Angeles right along with it.
In Colorado, Rain Barrels Are Illegal. Yup. GroovyGreen.com – Start Today :: Save Tomorrow
We could have a whole other interesting conversation about land use and government people sticking their nose in your business, along with the wisdom of having big cities in deserts.
Finest regards,
troy