The Monterey Shale
extends through most of central California and has as much as 15.4 million barrels of oil, according to an estimate.
The Obama Administration gave companies the go-ahead to use hydraulic fracturing -- or fracking -- to try and tap that gas, but a judge on Monday ruled that the oil leases did not judge the environmental impact of fracking and are illegal, according to reports.
Shale oil is notoriously hard to tap, with rock and other organic material throughout the oil deposits. And fracking, of course, is notoriously controversial and quite possibly dangerous: The process involves blasting a high-pressure mixture of sand, water and still-unknown chemicals through shale formations, which then forces the valuable oil to bubble to the surface. This has been known to lead to small earthquakes as well as health hazards.
The Bureau of Land Management issued in 2011 two leases that would have allowed "oil and gas development" on a pair of 2,500-acre tracts, according to Reuters.
And the BLM erred, according to U.S. District Judge Paul Grewal in San Jose, in declining to conduct any kind of study on fracking's environmental impact.
Grewal's ruling came in a lawsuit brought by the Center for Biological Diversity and the Sierra Club.
All drilling is now off until the environmentalists and the oil companies can come to an agreement, according to Reuters. If not, there will be more litigating.
The environmentalists hailed the ruling as a milestone -- a first-ever push for accountability over the use of fracking.
"It's the first federal court opinion we're aware of that explicitly holds that federal agencies have to analyze the environmental impacts of fracking when carrying out an oil and gas leasing program," attorney Brendan Cummings told Reuters.
It should be noted that no less an environmentally-minded man than Gov. Jerry Brown recently praised fracking as a possible method to unlock California's untapped shale oil reserves -- and a study released in March estimated that fracking along the entire Monterey Shale, which extends into the economically depressed San Joaquin Valley, could create over 500,000 jobs.