Oil extraction method widely used in California with little oversight

Reporting from Sacramento—

Energy companies across California are injecting a mysterious mix of chemicals into the ground to tap oil deposits while frustrating attempts to regulate the controversial process, known as hydraulic fracturing.
http://www.latimes.com/news/local/la-me-oil-fracking-20120315,0,4631157.story

Article courtesy of The Los Angeles Times by Michael J. Mishak