Basic Answer: Scripps Water is free NSW (Natural Sea Water) that is available at Scripps Pier in La Jolla. Its filtered for use by the Birch Aquarium and they graciously allow hobbyists access. Please be polite and respect the free benefit they provide us. There's a small hose at the front of the pier where you can pull in and fill up.
For more in depth information regarding Scripps Water, check out this link
http://www.sandiegoreefs.com/forums/showthread.php?t=11201
there are multiple posts with comments and current info.
And for directions, go to the main page and click on 'Directions to Scripps'