A new government assessment has identified two areas covering nearly all of Southern Maryland that have the potential for hydraulic fracturing to mine natural gas.

The practice, known as fracking, has been under way for years in parts of Pennsylvania known as the Marcellus Shale, which also extends into western Maryland. Mining companies drill wells into the shale and inject chemical-laced water and sand to crack the rock and release recoverable natural gas or oil.

Using existing wells and test wells, the U.S. Geological Survey developed estimates of the amount of gas in five Mesozoic basins along the East Coast. The agency identified nine other basins that likely have supplies of gas, but did not assess the quantity because of lack of data.

“We try to emphasize there is a range of possibilities,” Jim Coleman, research geologist for the USGS, said of the June report’s findings.

The Taylorsville basin runs through some of Virginia and across the Potomac River to cover much of Charles County, some of Prince George’s and up to Annapolis. That basin was assessed and found to contain an estimated 1,064 billion cubic feet of natural gas.

Some of the Delmarva basin covers parts of Maryland’s Eastern Shore, extends across the Chesapeake Bay and into much of St. Mary’s and Calvert counties. Although that basin was not assessed, Coleman said, it likely contains some amount of natural gas.

Coleman said the amounts of gas predicted in the five newly assessed basins along the East Coast have an estimated 3.9 trillion cubic feet of gas, an amount that pales in comparison with that of the Marcellus Shale, which has an estimated 84 trillion cubic feet of gas. However, he said, that does not rule out the oil and gas industry’s potential to extract the resource in Maryland.

“Most of industry already knows about these areas,” he said.

“It doesn’t say it’s going to happen, but it says it could happen,” Mitch Jones, common resources program director of the Food and Water Watch, said of fracking in Southern Maryland. “We don’t really know the full scale of what we could be looking at” based on the unassessed basins, he said.

Food and Water Watch advocates for safe food and water supplies for consumers and to protect natural resources.

Gov. Martin O’Malley (D) has a standing executive order not to issue fracking permits, essentially prohibiting the practice in Maryland while a commission studies it.

That order could be lifted at any time, Jones said, which potentially would open up the state to fracking.

Jones cited a variety of environmental problems and public health issues that he said are linked to fracking in other areas, including contamination of drinking and surface water by the chemicals used in the process, migration of the methane gas into drinking water and the dilemma of how to dispose of the used fracking solution.

“We are calling for a statewide ban on hydraulic fracturing,” Jones said. He said the group is supporting a bill that Del. Shane Robinson (D-Montgomery) plans to introduce in the 2013 legislative session.

“I think it comes down to a cost-benefit analysis,” Robinson said.

The delegate acknowledged there would be some benefits of tapping into a new energy source, but said “the [relatively small] amount of gas within Maryland is not going to affect” the nation’s energy independence.

He cited the cost of road upgrades to handle increased trucking and the potential for water contamination accidents if fracking were permitted in the state.

“It’s pretty clear, even with regulation, there are going to be accidents if it happens in Maryland” based on reports of contamination of water supplies in other states, Robinson said.

The U.S. Environmental Protection Agency also is studying hydraulic fracturing, citing concerns of potential environmental impacts including stress on groundwater supplies and air pollution.

The USGS report does not look at the legality or economic issues of drilling, Coleman said, only whether the resources exist or not. The East Coast estimates are part of a nationwide project during the past decade to assess domestic petroleum basins.

“Americans are currently benefiting from a plentiful supply of natural gas from continuous resource accumulations similar to the ones considered in this assessment,” Marcia McNutt, USGS director, said in a statement. “By providing estimates of undiscovered resources, the USGS helps both producers and consumers understand the future for our domestic supply and the geographic locations for impacts from energy development.”