Last week, California Governor Schwarzenegger signed the California artificial reef bill, laying the ground work for artificial reefing projects in California.
This bill limits the government's liability for scuba diving and fishing accidents on artificial reefs. This was a huge impediment to laying artificial reefs in the California waters.
There are already a large number of artificial reefs off California, as most west coast divers know. Surprisingly, most of these are composed of quarry rock, rather than ships and barges. Others are made of light poles, pier pilings, concrete chimneys, and old streetcars. Here is a list of artificial reefs and coordinates, which also says what each are made of.
This initiative was pushed by California Ships to Reefs, so I expect newer reefs to be made of unsalvageable ships. While there are a few artificial reefs made of ships off California, like the Yukon in San Diego, they are definitely in the minority.
Not only do artificial wrecks provide shelter for fish, but they also provide a relatively safe wreck diving environment. They tend to be safer than genuine wrecks because all hazardous materials are removed prior to sinking.
Photo from yukonsite.wordpress.com