LA area rock question

Greetings,

Im new to the group, Ive kept koi in small ponds for around 15 years, but
recently took the plunge, heh heh, and dug myself a 600 or so gallon
flexible liner pond. Fortunately my climate makes this a year round hobby
and Im looking forward to that.

Right now I am using seed water from the old pond, and a barrel style
trickle bio ball filter which ran in my old 100 gallon pond for several
weeks, so I anticipate the new pond to have its bio system up very quickly.
I added 4 small koi which inhabited my old pond but wont add additional fish
for several weeks.

Anyway, on to my question, can any fellow pond o philes suggest a local
source ( Long Beach area) for landscaping rock? I need at least 50 or so
natural boulder rocks for my pond borders and waterfall construction. Im
planning to surround the back and sides with natural rock border and the
front edge with flagstones. Then build up a waterfall area , probably
without mortar to camoflage my filter unit which connects to the pond via a
5 gallon pre formed streambed section which I will also fill and hide with
boulders and rock.

Thanks for your help

D