Supporters and opponents of shale gas development resumed their war of words on Thursday as Pennsylvania’s natural gas industry gathered for Shale Gas Insight, its annual forum on the development of the Marcellus Shale, one of America’s biggest gas reserves.

Industry and government leaders argued that fracking for natural gas can and is being done without endangering public water supplies, and that industry is taking increasing steps to ensure that fracking chemicals don’t seep in to groundwater.

But several hundred anti-fracking protesters outside the Pennsylvania Convention Center urged the continuation of existing bans on unconventional drilling in New York state and the Delaware River Basin, and called for a halt to the multibillion-dollar gas industry that has boomed in Pennsylvania since 2008.

Pennsylvania Governor Tom Corbett, a strong supporter of the gas industry, attacked protesters, saying that to stop unconventional gas production would destroy an industry that has generated thousands of jobs and millions of tax dollars.

“It’s beyond belief that there are still people who would trade this progress for a return to the status quo,” he said in a speech at the opening of the two-day event.

The Republican governor is fighting to preserve a section of a new law that would restrict the ability of municipalities to control gas development. That part of the law was struck down by a state court earlier this year, and Corbett’s appeal will be heard by the state Supreme Court on Oct. 17.

Corbett said 240,000 people now work in the natural gas industry or in businesses that serve it, and that workers in the gas-rich Marcellus Shale that underlies about two-thirds of Pennsylvania make $30,000 a year more than the average Pennsylvanian.

For all the success of shale development, public confidence is not as strong as it could be,” – Williams, XTO Energy

He said the industry has defied “predictions of disaster from people with no knowledge of the industry” and has shown that fracking for natural gas can be done without contaminating air and water.

But Jack Williams, President of XTO Energy – a company acquired by ExxonMobil in 2010 for over $40 billion, in large part for its unconventional gas development expertise – conceded that the industry needs to do more to win public support.

“For all the success of shale development, public confidence is not as strong as it could be,” Williams told the meeting.

Despite many independent studies affirming the safety of shale production, there is still a “high level of concern” about the impact of shale drilling on communities and the environment, he said.

To help overcome those fears, companies like XTO are disclosing fracking chemicals, publishing guidelines on well construction, site restoration and water management, and conducting water-quality tests within 2,500 feet of Pennsylvania drilling sites, Williams said.

He said there continues to be “a lot of misinformation out there” on the safety of fracking but expressed confidence that public confidence can be built up in Pennsylvania and other northeastern states that are relatively new to gas drilling if they follow the experience of Texas.

He said some 20,000 wells have been drilled in the Barnett Shale at Fort Worth over the last decade and there have been no instances of shale development harming drinking water there.

Outside the hall, protestors held signs with slogans including “Frack Makes Children Sick” and “Don’t Drill the Delaware” as speakers called for a halt to the practice.

Tracy Carluccio, deputy director of the Delaware Riverkeeper Network, an environmental group, said academic and other studies have shown that unconventional gas development threatens aquifers with chemicals that are hazardous to human health.

“These studies are finding that aquifers will be or already have been contaminated,” she said.

Carluccio said cement casings used in fracking aren’t strong enough to prevent chemicals leaking into aquifers, and that regulations in Pennsylvania have failed to set high enough safety standards.

Some Pennsylvania legislators are seeking a moratorium on fracking despite the overwhelming size of the state’s gas industry, she said.