In the 1500's California went through an 80 year drought. During
the winter there were blizzards in Central California, the Salinas
river froze solid where it flowed into the Monterey Bay. During the
summer there was no humidity, no rain, and temperatures in the
hundreds for many months. During one year in the 1840's there
was no measurable rain in Santa Barbara. (The highest measured
rainfall in an hour also was in Southern California, 11 inches
in an hour) The same native plants that lived through that are
still on the hillsides of California. California native plants that
do not normally live in the creeks and ponds are very drought
tolerant.
The best way to find your plant is to check
www.mynativeplants.com
and do not water at all. But if you want a simple list of drought
tolerant plants that can work for your garden here are some.