SAN FRANCISCO -- Underneath much of Central and southern California sits one of the largest deposits of shale oil in the United States, boasting a motherlode of some 15 billion barrels of oil.

While the Monterey Shale's unique geology has prevented energy companies from unleashing a new West Coast energy boom, California regulators have begun to take the first steps in regulating hydraulic fracturing (or "fracking"), a controversial practice decried by environmentalists and the most promising solution for retrieving said oil.

The process of injecting a mixture of water, sand and other chemicals into a well in order to stimulate the flow of oil or natural gas, fracking is especially helpful in accessing energy deposits in shale formations that would otherwise be out of reach using traditional methods.

Kassie Siegel of the nonprofit Center for Biological Diversity, which is in the process of suing the state for doing what it calls an insufficient job of regulating fracking, argues that the practice has the potential to do irreparable harm to the environment. She notes that a quarter of all the chemicals used in fracking are known carcinogens, and some people living near fracked wells have reported health ailments like vomiting, nausea and seizures.

On the other hand, industry representatives have pointed to a recent year-long study conducted in Southern California's Ingleside Oil Field that found no negative health, air quality or seismic effects from the fracking occurring there. The study, paid for by Plains Exploration & Production Company as part of a lawsuit against the energy producer, has been criticized by environmentalists for not looking at the long-term heath effects of fracking.

Earlier this month, the California Department of Conservation's Department of Oil, Gas & Geothermal Resources (DOGGR) released a preliminary set of regulatory guidelines for all fracking activities occurring in the state.

During a phone conference with members of the media last week, state regulators noted that many of the rules they're planning to put in place mandate practices already standard across the energy industry. However, one area headed for change is the requirement that companies disclose all the chemicals they use in fracking.

The new rules mandate that all chemicals used in the fracking process be disclosed within 60 days after the completion of fracking and that the state be notified 10 days before fracking occurs.

Presently, energy producers aren't required to tell anyone where or when they're using hydraulic fracturing, although many companies have started to do so on a voluntarily basis through industry-run site FracFocus.org after state regulators asked them to do so earlier this year. Under the new regulatory regime, reporting chemicals on FracFocus would become mandatory.

FracFocus now lists information for just over 600 fracked wells in California. According to Western States Petroleum Association Spokesman Tupper Hull, a recent survey found that of the 47,000 active wells, only 628 utilize hydraulic fracturing.

Some environmentalists have questioned the wisdom of relying on a private, industry-run website to host this information, especially when said site isn't required to comply with Freedom Of Information Act requests. However, on last week's conference call, regulators explained that the state retains the ability to extricate itself from FracFocus at any time and build its own site if they feel FracFocus isn't doing an adequate job. It would likely take California at least three years to get its own version of FracFocus online, whereas the industry site is ready now and has been hosting voluntary disclosures for over a year.

"When the companies voluntarily disclosure info, we're happy," said Scott Anderson, a senior policy advisor at the Environmental Defense Fund. "But voluntary disclosure is insufficient."

Surprisingly, over the past year or so, many of the companies engaging in fracking have come to the same conclusion as Anderson. When Wyoming adopted a mandatory disclosure rule in 2010, the state imposed it over significant industry opposition. However, as Anderson explained, the industry has come to see mandatory disclosure as a way to overcome some of the widespread hostility toward fracking. "There's no reason for people to trust data that's doled out by these companies on a voluntary basis," he explained.

This newfound openness toward letting the whole world know about precisely which chemicals they're pumping into the ground isn't exactly universal--it stops at a line marked "trade secrets."

Firms in states with mandatory disclosure rules, such as the ones proposed in California, are able to avoid releasing information about certain compounds by saying that making this information public would put them at a competitive disadvantage against other drilling firms.

The California rules would allow the state to challenge trade secrets claims and require immediate disclosure if a heath professional declares a medical emergency.

In an editorial published a few days after the release of this new set of regulations, the Sacramento Bee came down strongly in favor of the state demanding the strongest level of disclosure possible:

As valuable as fossil fuels are, California groundwater is a much more treasured resource, and it needs to be protected. We don't allow food companies to withhold the fact they might be adding carcinogenic chemicals to their recipes. Why should we allow oil companies to do the same with fracking?

California must insist on full disclosure on fracking chemicals. If regulators think they lack the authority to order such disclosure, then the Legislature will need to pass legislation to make it the law of the land.

Siegel came out even more forcefully. "These draft regulations would keep California's fracking shrouded in secrecy and do little to contain the many threats posed by fracking," she said in a statement. "These regulations are going to have to be completely rewritten if the goal is to provide real protection for our air, water, and communities."

Formal discussion of the fracking rules will begin early next year. During that process, regulators plan on meeting with both environmentalists and industry representatives and will host a series of town hall discussions with members of public in oil-producing areas across the state.

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  • In this file photo from Oct. 14, 2011, a drilling rig is seen in Springville, Pa. State regulators blamed faulty gas wells drilled for leaking methane into the groundwater in nearby Dimock, Pa. It was the first serious case of methane migration said to be related to the Pennsylvania Marcellus Shale gas field drilling boom. (AP Photo/Alex Brandon, FILE)

  • British police secure the area where demonstrators erected a mock fracking rig with a banner reading 'No fracking in the UK' in a protest against hydraulic fracturing for shale gas outside the Houses of Parliament in London on December 1, 2012. AFP PHOTO / JUSTIN TALLIS

  • SPRINGVILLE, PA - JANUARY 18: A truck with the natural gas industry, one of thousands that pass through the area daily, drives through the countryside to a hydraulic fracturing site on January 18, 2012 in Springville, Pennsylvania. (Photo by Spencer Platt/Getty Images)

  • SAN FRANCISCO, CA - MAY 30: Protestors stage a demonstration against fracking in California outside of the Hiram W. Johnson State Office Building on May 30, 2013 in San Francisco, California. Dozens of protesters with the group Californians Against Fracking staged a protest outside of California Gov. Jerry Brown's San Francisco offices demanding that Gov. Brown ban fracking in the state. (Photo by Justin Sullivan/Getty Images)

  • People demonstrate on August 3, 2013 in La Petite Brosse, near Jouarre, outside Paris, to protest against an exploratory oil shale drilling, considering that it opens the door to the exploration of shale gas in the Parisian Basin. Banner reads 'Stop gas and oil shale'. AFP PHOTO / PIERRE ANDRIEU

  • In this Nov. 26, 2012 photo, Steve Lipsky demonstrates how his well water ignites when he puts a flame to the flowing well spigot outside his family's home in rural Parker County near Weatherford, Texas. The U.S. Environmental Protection Agency had evidence a gas company's drilling operation contaminated Lipsky's drinking water with explosive methane, and possibly cancer-causing chemicals, but withdrew its enforcement action, leaving the family with no useable water supply, according to a report obtained by The Associated Press. The EPA's decision to roll back its initial claim that hydraulic fracturing, or “fracking,” operations had contaminated the water is the latest case in which the federal agency initially linked drilling to water contamination and then softened its position, drawing criticism from Republicans and industry officials who insisted they proved the agency was inefficient and too quick to draw conclusions. (AP Photo/LM Otero)

  • In this file photo of Jan. 17, 2013, Yoko Ono, left, and her son Sean Lennon visit a fracking site in Franklin Forks, Pa., during a bus tour of natural-gas drilling sites in northeastern Pennsylvania. Ono and Lennon have formed a group called “Artists Against Fracking,” which has become the main celebrity driven anti-fracking organization. (AP Photo/Richard Drew, File)

  • In this March 29, 2013 file photo, a worker checks a dipstick to check water levels and temperatures in a series of tanks at a hydraulic fracturing operation at a gas drilling site outside Rifle, Colorado. (AP Photo/Brennan Linsley)

  • In this March 29, 2013 file photo, a worker switches well heads during a short pause in the water pumping phase, at the site of a natural gas hydraulic fracturing and extraction operation outside Rifle, in western Colorado. (AP Photo/Brennan Linsley)

  • In this March 29, 2013 file photo, workers tend to a well head during a hydraulic fracturing operation at a gas well outside Rifle, in western Colorado. (AP Photo/Brennan Linsley)

  • Josh Fox, director of the anti-fracking, Oscar-nominated documentary “Gasland” testifies during a House Committee hearing on oil drilling, "fracking" legislation at the Illinois State Capitol Tuesday, May 21, 2013, in Springfield, Ill. (AP Photo/Seth Perlman)

  • This is a Thursday Aug. 15, 2013 image of the Cuadrilla exploration drilling site in Balcombe, southeast England. (AP Photo/Gareth Fuller/PA)

  • A child plays near a farmers' protest in an area where oil company Chevron plans to put a drilling rig exploring for shale gas in the south-eastern Polish village of Zurawlow on June 11, 2013. AFP PHOTO / JANEK SKARZYNSKI

  • Protesters hold a banner during a protest outside of the Momentive resin plant, Monday, July 8, 2013, in Morganton, N.C. Dozens of environmental activists blocked a chemical plant Monday to protest against the company's sale of products used in the natural gas drilling process called hydraulic fracturing, or fracking. (AP Photo/The News Herald, Mary Elizabeth Robertson)

  • A fracking rig exploring for shale gas of oil company Chevron on June 11, 2013 in a village of Ksiezomierz in south-eastern Poland. AFP PHOTO / JANEK SKARZYNSKI

  • People demonstrate on August 3, 2013 in La Petite Brosse, near Jouarre, outside Paris, to protest against an exploratory oil shale drilling, considering that it opens the door to the exploration of shale gas in the Parisian Basin. AFP PHOTO / PIERRE ANDRIEU

  • Opponents of hydraulic fracturing in New York state attend a news conference and rally against hydraulic fracturing, also known as fracking, on January 11, 2012 in New York City. (Photo by Spencer Platt/Getty Images)

  • Eric Weltman of Food & Water Watch attends a news conference and rally against hydraulic fracturing, also known as fracking, in New York State on January 11, 2012 in New York City. (Photo by Spencer Platt/Getty Images)

  • Opponents and supporters of gas-drilling, or fracking, walk into the last of four public hearings on proposed fracking regulations in upstate New York on November 30, 2011 in New York City. (Photo by Spencer Platt/Getty Images)

  • Engineers on the drilling platform of the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • Engineers at work on the drilling platform of the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • General views of the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • Engineers look at the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • A lump of shale rock on display at the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • Engineers on the drilling platform of the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • Engineers at work on the drilling platform of the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • Drill heads on display at the entrance to the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • An engineer displays a lump of shale rock at the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • Actor/director Mark Ruffalo (C) speaks at the Hydraulic Fracturing prevention press conference urging the protection of the drinking water source of 15 million Americans at Foley Square on April 25, 2011 in New York City. (Photo by D Dipasupil/Getty Images)

  • (L-R) Actor/director Mark Ruffalo, Denise Katzman, Wenonah Hauter, and Water Defense co-founder/campaign director Claire Sandberg attend the Hydraulic Fracturing prevention press conference urging the protection of the drinking water source of 15 million Americans at Foley Square on April 25, 2011 in New York City. (Photo by D Dipasupil/Getty Images)

Correction: The article originally incorrectly stated the Monterey formation had the largest shale oil reserves in the United States.

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