A new report says public debate over hydraulic fracturing should be broadened to include the amount of water used and disposed of underground as part of the controversial oil field technique also known as "fracking."

The paper released Thursday by Oakland-based nonprofit Pacific Institute notes that the national discussion of fracking has focused on identifying the sometimes toxic chemicals injected underground as part of the process.

"But while chemical disclosure can be useful for tracking contamination, it may not be the most important issue for water resources," the authors note. "Other key issues also deserve major attention and analysis, such as the massive water requirements for hydraulic fracturing and the potential conflicts with other water needs, including for ecosystems and for agriculture."

The report could have big implications for Kern County, which has more fracking activity than perhaps anywhere else on the West Coast.

The report's publication comes at a crossroads. California lawmakers are considering bills that would require greater disclosure of fracking information, including how much water is used in the process and what is done with it afterward. Meanwhile, state regulators are drawing up the first California rules specific to fracking.

The technique was pioneered in the 19th century and practiced in Kern for decades. It injects water, sand and chemicals underground at high pressure to break up rock formations in a way that promotes oil production. Recent attention on the process has sparked fears that it may cause groundwater contamination and seismic activity.

There is some question as to how much of the study applies to California. It focuses on fracking for natural gas, which is rare here. Most if not all fracking done in Kern County is intended to produce crude oil, though the process is much the same.

The study's co-author, Pacific Institute researcher Heather Cooley, asserted that the report's conclusions "are certainly applicable for California."

"We have concerns about water availability in California, so if there is a large increase in fracking, it could ... put strain on California's existing resources," Cooley said in an interview.

Tupper Hull, vice president of the trade group Western States Petroleum Association, questioned whether there will be a large increase in fracking in California. He said it is still unclear whether the huge Monterey Shale find beneath much of the southern San Joaquin Valley will respond to fracking, even as many in the industry hope it will.

Natural gas fracking wells typically use between 2.3 million and 3.8 million gallons of water, according to the study, which also cites a single Texas gas well that used 13 million gallons.

There is no reliable data on how much the average oil fracking well uses in California, though industry data published at fracfocus.org details jobs that used less than 200,000 gallons of water, while others used as much as 1.5 million gallons.

Using such large volumes can pit energy against agriculture in a bidding war. The study mentions a situation earlier this year in Colorado in which natural gas companies successfully bid on water that has historically gone to farmers.

Recycling water used in fracking could help alleviate this problem, the study says. But that doesn't normally happen; instead, the water is usually injected underground as waste. WSPA has confirmed that underground disposal of fracking water is the norm in California.

The study says this method of disposal presents the same groundwater contamination and earthquake risks as fracking itself.

But there are barriers to reusing fracking water, according to the study. It requires space for storage, transportation to treatment facilities and energy for processing.

Cooley said oil and natural gas producers must weigh the price of fresh water and underground disposal against the cost of treating frack water.

"Depending on the options available, it's often cheaper to dispose of it in an underground well," she said.

Hull, the trade group vice president, said he didn't know why more companies don't reuse fracking water, adding that some companies have recycled it.

"I'm aware there are some companies that have had projects where they've treated and reused the water or made it available for agricultural uses," he said.