It is not illegal to pressure wash your driveway in California.
However it is illegal to allow the water from pressure washing your driveway or sidewalks to enter a storm drain in California.
As long as you prevent the water from draining into a storm drain from pressure washing your driveway or sidewalk you can legally pressure wash your driveway, sidewalk, house etc in California.
According to California regulations and San Diego California code which usually applies to other major cities in California as well.
It is illegal to discharge polluted wash water from pressure washing, power washing or hosing down outdoor surfaces into the Municipal Separate Storm Sewer System (MS4) (San Diego Municipal Code ยง43.0304).
Penalties associated with these violations can be up to $10,000.00 per day per incident.
So you're free to pressure wash your driveway or sidewalk or anything else in California as long as you don't allow the water to get into the store drain.