For a while it looked like the oil industry was just going to sit there and take it from the environmentalists. And for several hours in Bakersfield Wednesday, that's exactly what happened.

Representatives of the Sierra Club and the Center for Biological Diversity hammered away at the state's proposed rules for regulating the oil field technique known hydraulic fracturing. They called for additional safeguards, tougher penalties for violations and closer state oversight.

Not until almost the end of the state-sponsored "fracking" workshop did anyone from the industry speak up. When they finally did, about three hours into the workshop at the Four Points by Sheraton, the industry's comments were short on specifics and long on caution.

Industry spokesmen told visiting officials from the state Division of Oil, Gas and Geothermal Resources and its parent agency, the Department of Conservation, that oil and gas production is a big job engine and generator of tax revenues. All of that could be jeopardized, they warned, by unreasonable regulations on fracking.

"It would be tragic if the communities that have suffered under a cloud of economic malaise and anemic public services for far too long are denied the opportunity to grow and prosper because decision makers who neither live here nor understand our economic situation are allowed to prevent the beneficial use of a safe and proven technology," said Michael Turnipseed, executive director of the Kern County Taxpayers Association.

Similar concerns were voiced by three industry groups and four oil company representatives.

That's it, then? Nothing more than a plea to spare Kern County's main economic pillar?

Not exactly. As trade group representatives confided before and during the event, they plan to hold their peace until the state enters a formal rulemaking process in April or May. That's when they plan to get specific about proposed fracking rules.

What that meant Wednesday was that environmentalists took repeated shots at a controversial but highly effective technology -- and no one fired back.

Fracking injects sand, large amounts of water and small concentrations of sometimes-toxic chemicals underground at high pressure to break up rock formations and release oil and natural gas. Credited with opening access to vast petroleum reserves in other states, it has been done in western Kern County for decades without reports of groundwater contamination.

In front of an audience of about 50 people, most of them from Kern's oil industry, Sierra Club fracking expert Tom Williams, two lawyers from the Center for Biological Diversity and Santa Paula resident Marianne Ratcliff asked state officials to strengthen -- and in no case weaken -- draft rules released in December.

They asked for several measures not envisioned in the draft rules, such as baseline water sampling and seismic testing before and after frack jobs.

They recommended tougher cementing requirements to ensure that the high pressures associated with fracking do not end up rupturing well casings and allow toxins to seep into nearby groundwater.

They requested pre-fracking disclosure of the chemicals injected underground, not 60 days afterward, as the state has proposed.

Ratcliff, touching on one of the California fracking debate's most sensitive issues, asked that the state simply forbid the use of any chemicals that the industry refuses to identify on the grounds that their disclosure would violate the California Uniform Trade Secrets Act.

At times the comments got pointed. Ratcliff accused industry players of "cutting corners" on environmental rules. Other speakers seemed to imply that state regulators had grown too cozy with the industry.

Such words prompted a heated response by the director of the Department of Conservation, Mark Nechodom, a trained scientist. Uttering the meeting's very last words, he said he "took umbrage" at suggestions that his agency was anything less than independent.

Nechodom emphasized that the proposed rules were not intended to be onerous for oil companies, but neither were they "meant to make profits for the oil and gas industry."

More fracking workshops are expected to take place soon in Monterey, Santa Barbara and Sacramento.