A Cal State Bakersfield geologist is leading a "herculean" local study designed to help bring state oil regulators into compliance with federal rules for protecting drinking water.

Professor Jan Gillespie recently began working with CSUB graduate students to review existing chemical and electrical analyses of groundwater from the Kern County portion of the Central Valley.

The idea is to identify the depths at which local groundwater reaches 10,000 parts per million of total dissolved solids, which is the federal threshold for water requiring protection.

For decades, California oil regulators have operated on the less strict definition of water deserving protection of 3,000 parts per million.

The difference between the two definitions arose as a point of some contention in 2011, when an audit commissioned by the U.S. Environmental Protection Agency pointed out that the state's definition was out of compliance with the federal standard.

The state Department of Conservation's Division of Oil, Gas and Geothermal Resources has since promised to adhere to the federal standards. But first it needs to know where underground water meeting the stricter definition exists.

The practical implications could be important to Kern's oil industry.

Petroleum producers often inject naturally occurring toxic gases and other waste materials into underground aquifers where the water is deemed undrinkable. Putting the federal standard into effect will give them fewer places for disposal operations.

Dan Wermiel, DOGGR's technical programs manager, described Gillespie's study as "herculean" at a meeting of industry and regulators Thursday in Bakersfield.

He noted that the study won't develop new data, only look at existing information.

Gillespie wrote in an email that she plans to solicit the help of local oil producers that "have a lot of data we will need for the study." She added that she hopes to finish the study within 18 to 24 months.

Changing the state's drinking water definition is part of a larger project by DOGGR to revise its underground injection program, which the division acknowledged in November 2012 were badly in need of updating.