Pamela Woodruff can't be sure, but she suspects the loud, sustained noise coming from an oil operation near her southwest Bakersfield home earlier this year means someone has been fracking in her neighborhood.

Admittedly, Woodruff wouldn't know how to spot the controversial technique that, here and across the country, pumps water, sand and chemicals underground at high pressure to free up oil deposits. But she has heard stories about fracking, and they worry her.

"I just really wonder what is going on there," she said.

So do a lot of Californians. And they're likely to find out.

As fracking, or hydraulic fracturing, becomes more common in California and especially Kern County, state lawmakers, regulators and environmentalists are pushing for greater transparency regarding the practice.

Already some oil producers are responding by voluntarily posting information about their fracking operations to an online national database,

New detail

The result is an easily accessible public repository that reveals local fracking activity in unprecedented detail. Although it is unclear how complete the database is, and its records go back no further than last year, the website shows what chemicals and how much water have been injected where and at what depths at 78 California frack wells, all but five of them in Kern County.

For instance, FracFocus pinpoints a cluster of 58 wells fracked last year between Lost Hills and McKittrick by XTO Energy/ExxonMobil. Many of these frack jobs pumped several hundred thousand gallons of water into wells about 3,000 feet deep.

Another cluster of 12 wells in the Wasco-Shafter area was fracked last year by Occidental Petroleum Corp. These generally used greater volumes of water than the McKittrick wells -- in one case, more than 1.5 million gallons, or close to 5 acre feet of water -- at depths of about 6,000 to 8,000 feet, according to data Oxy posted to the website.

Calls for more

Two bills pending in the state Legislature would build on this trove by requiring still more public information about fracking activity. One would make oil companies turn over the same kind of data available at FracFocus, as well as information on where the fracking water came from and what was done with it afterward. The other bill would force companies to notify nearby property owners before fracking.

In the meantime, State Oil and Gas Supervisor Tim Kustic, head of the Division of Oil, Gas and Geothermal Resources, sent out a notice March 28 urging oil companies to post information to FracFocus on a strictly voluntary basis.

"In the absence of requirements that operators report when, where and how they conduct hydraulic fracturing operations," DOGGR spokesman Don Drysdale wrote in an email Friday, "the Division is asking that operators volunteer some of that information."

A sensitive issue

Fracking has been useful to the domestic energy industry because of its proven potential to unlock vast oil and natural gas reservoirs in places like North Dakota, Texas and Pennsylvania. There the practice has received heavy scrutiny and no small amount of criticism because of claims that it could threaten drinking water and even trigger seismic activity.

There are indications that fracking activity in the state will only increase. Oxy and other local operators are gearing up to tap the Monterey Shale, a huge reservoir beneath Kern and other parts of Central California. People in the industry say producing oil there will require extensive fracking.

Willing to comply

Industry representatives say they would like to see disclosure rules become law, if only to relieve people's safety concerns.

The California Independent Petroleum Association is encouraging its members to comply with DOGGR's request for information.

"We feel disclosing where, when and how the process is being used will only bolster our case that this is a common and safe practice in California," said the association's chief executive, Rock Zierman.

Venoco Inc., a Denver-based oil producer operating in Kern, intends to send fracking records to FracFocus but hasn't done so yet, said Mike Edwards, the company's vice president of corporate and investor relations.

"I think since the order or the notice came out just last month, it's more of a yeah, in concept it'd be something we're supportive of," he said. "As far as the implementation time, I don't know what it's going to take for us to start implementing it."

A spokeswoman for one of Kern County's larger oil producers, Aera Energy LLC, said the company has agreed to begin reporting to FracFocus starting in May. But Aera's support for the initiative is conditional, she added.

"We support reasonable disclosure of completed hydraulic fracturing operations where uniform rules and protocols are in place to ensure that competing companies are disclosing this information in the same manner," spokeswoman Susan Hersberger wrote in an email.