The rush to drill for natural gas in Pennsylvania has put state officials in the unsettling position of playing catch-up with environmental regulations.

The state Department of Environmental Protection is hiring new inspectors as fast as it can, and developing new rules for drillers. But more needs to be done in Harrisburg to ensure this aggressive push for domestic fuel doesn't pollute drinking water.

The industry is expected to drill up to 1,750 wells this year in the Marcellus Shale region, which holds vast deposits of natural gas in mile-deep rock. Last year, 763 wells were drilled.

Representatives of the Marcellus Shale Coalition, an industry trade group, point out that not a single case of groundwater contamination has been linked to their drilling technique, called hydraulic fracturing or "fracking." It involves pumping up to three million gallons of water (per well), combined with sand and chemicals, more than a mile underground to shatter the rock and release the gas.

But fracking does carry potential risks to the environment. Those concerns are causing government officials elsewhere to proceed cautiously on Marcellus drilling. New York state has imposed a moratorium on Marcellus wells until it completes an environmental-impact assessment.

And the U.S. Environmental Protection Agency last week launched a two-year study to determine whether fracking is a danger to groundwater. An EPA study in 2004 deemed the process safe, but the Obama administration is questioning the thoroughness of the Bush-era review.

In Pennsylvania, it's full speed ahead with Marcellus drilling, including widespread leasing of state forest land. There is no comprehensive set of laws aimed specifically at regulating this new industry, nor a tax on the production of natural gas that exists in most other gas-producing states. Gov. Rendell correctly seeks to impose a severance tax again.

Another useful tool for protecting the environment is a bill proposed by Rep. Camille "Bud" George (D., Clearfield) that would coincide with pending DEP regulations. George's measure would require more inspections of Marcellus wells and expand to 2,500 feet (from 1,000 feet) the "pollution zone" in which groundwater contamination is presumed to be caused by a well operator.

George also would require drillers to disclose the specific chemical concentrations of their fracking fluid. Many drillers withhold that information, arguing it's proprietary. U.S. Interior Secretary Ken Salazar told Congress last week that he, too, is considering requiring drillers to disclose the chemicals used in fracking.

Some industry leaders agree; some don't. Disclosure of the chemicals being pumped into the ground ought to be a minimum standard of environmental protection as regulators try to keep pace with this burgeoning industry.