California is on the verge of a new gold rush. Expanded hydraulic fracturing — or “fracking” — at the Monterey Shale formation is sparking estimates that 15 billion barrels of oil could be accessed, along with millions of jobs and huge contributions to the domestic energy supply.

Even the state’s green-friendly Democratic governor, Jerry Brown, says “the potential is extraordinary.”

But standing in the way is a flurry of anti-fracking bills. At last count, 10 were on the table, all introduced by Democrats seeking tighter controls over the controversial technology.

Some of the measures take aim at how crude is extracted from rock layers beyond the reach of conventional drilling.