EPA Heightens Scrutiny of Pa.'s Marcellus Shale Tugging on rubber gloves, a laboratory worker kneels before a gushing spigot behind Kim Grosso's house and positions an empty bottle under the clear, cold stream. The process is repeated dozens of times as bottles are filled, marked and packed into coolers. After extensive testing, Grosso and dozens of her neighbors will know this week what may be lurking in their well water as federal regulators investigate claims of contamination in the midst of one of the nation's most productive natural gas fields. More than three years into the gas-drilling boom that's produced thousands of new wells, the U.S. Environmental Protection Agency and the state of Pennsylvania are tussling over regulation of the Marcellus Shale, the vast underground rock formation that holds trillions of cubic feet of gas. The state says EPA is meddling. EPA says it is doing its job. Grosso, who lives near a pair of gas wells drilled in 2008, told federal officials her water became discolored a few months ago, with an intermittent foul odor and taste. Her dog and cats refused to drink it. While there's no indication the problems are related to drilling, she hopes the testing will provide answers. "If there is something wrong with the water, who is responsible?" she asked. Who's going to fix it, and what does it do to the value of the property? A Monday, Feb. 13, 2012 photo shows a Cabot Oil & Gas wellhead in Dimock, Pa. The U.S. Environmental Protection Agency appears to be ramping up its interest in the Marcellus Shale a rock formation in Pennsylvania and surrounding states that is believed to hold the nation's largest reservoir of gas with investigations in both the northeastern and southwestern corners of Pennsylvania. The drilling industry accuses EPA of overreach. (AP Photo/Matt Rourke) Close Federal regulators are ramping up their oversight of the Marcellus with dual investigations in the northeastern and southwestern corners of Pennsylvania. EPA is also sampling water around Pennsylvania for its national study of the potential environmental and public health impacts of hydraulic fracturing, or fracking, the technique that blasts a cocktail of sand, water and chemicals deep underground to stimulate oil and gas production in shale formations like the Marcellus. Fracking allows drillers to reach previously inaccessible gas reserves, but it produces huge volumes of polluted wastewater and environmentalists say it can taint groundwater. Energy companies deny it. The heightened federal scrutiny rankles the industry and politicians in the state capital, where the administration of pro-drilling Gov. Tom Corbett insists that Pennsylvania regulators are best suited to oversee the gas industry. The complaints echo those in Texas and in Wyoming, where EPA's preliminary finding that fracking chemicals contaminated water supplies is forcefully disputed by state officials and energy executives. Caught in the middle of the state-federal regulatory dispute are residents who don't know if their water is safe to drink. EPA is charged by law with protecting and ensuring the safety of the nation's drinking water, but it has largely allowed the states to take the lead on rules and enforcement as energy companies drilled and fracked tens of thousands of new wells in recent years. In Pennsylvania, that began to change last spring after The Associated Press and other news organizations reported that huge volumes of partially treated wastewater were being discharged into rivers and streams that supply drinking water. EPA asked the state to boost its monitoring of fracking wastewater from gas wells, and the state declared a voluntary moratorium for drillers that led to significant reductions of Marcellus waste. Yet a loophole in the policy allows operators of many older oil and gas wells to continue discharging significant amounts of wastewater into treatment plants, and thus, into rivers.