Here are some great places to go if you love the idea that made Los Angeles County and its neighbors so desirable in the first place. Know that the Basin was NOT a desert, it was a GARDEN.
http://wheredothechildrenplayla.wordpress.com/ (check out their marvelous sidebar of links, including botanical gardens and parks)
http://www.theriverproject.org/people.html (particularly useful!)
http://lasgrwc2.org/Default2.asp (Los Angeles and San Gabriel Rivers Watershed Council)
might as well search it~~~