Big oil continues to buy natural gas leases in Pennsylvania's Marcellus Shale. ExxonMobil Corporation paid almost $1.7 billion for more than 300,000 acres.

Meanwhile, environmental concern over drilling has some calling for state money to pay for baseline water tests for state residents living near wells.

Baseline water tests for those living near new natural gas wells could cost up to $1,000 each. Advocates say it's important for residents to get the tests before any natural gas well is drilled close to their property.

Pennsylvania Rep. Mike Sturla says the state should pay for those tests through a tax or an impact fee on natural gas drillers. Sturla also says the industry should include a chemical tracer in the frack fluid used to drill the well.

"If we had an environmental stewardship fund, we could get a baseline on every well in the state of Pennsylvania," Sturla said. "If we had tracers we would know if it showed up 10 years from now, 20 years from now, 50 years from now. And we would know exactly which well it came from."

The frack fluid contains toxic chemicals. Chemical tracers are sometimes used by industry to track the flowback of frack fluid.

A spokesman for the Marcellus Shale Coalition says tracers are unnecessary because he says frack fluid has never contaminated any drinking water well. He says the Department of Environmental Protection has ways to track the origins of water contamination.