Kerry Grens searches for the answer to one of the most pressing questions: How will natural gas production affect Pennsylvania’s water?

Natural gas has been trapped deep below the surface of Pennsylvania for eons. But only in the past two years has the industry begun in earnest to tap the rich gas reserves of the Marcellus Shale -- a layer of rock thousands of feet down that runs from New York to West Virginia. Gas companies sunk nine hundred wells into the Pennsylvania Marcellus this year. With this new area in play, residents have a lot of questions. The most frequently asked: what will be the impact on their water. In part two of our series The Shale Game, WHYY's health and science reporter Kerry Grens searches for the answer.

Krafjack: We have carrots here. Spinach is done. There's scallions, two kinds of lettuce, beets...

The view from Emily Krafjack’s property in Mehoopany, Pennsylvania.Emily Krafjack's garden in Mehoopany Pennsylvania offers a panoramic view of Wyoming County. A bright red barn, horses munching grass, and off in the distance, a crease in the hillside where the Susquehanna River courses through. Four hundred feet down the road from her house, a gas company recently laid out a well pad and starting digging a well that will reach thousands of feet into the earth.

Krafjack: You stand up there at the well site and look at the house. It's very close. [Laughs] It don't look so bad from this view.

A year ago, before the construction began, Krafjack had noticed that gas company trucks were gathering at her neighbor Jim's house.

Krafjack: I knew something was up. At a township meeting that night he pulls me aside and says they're putting a well pad across the road from your house. And the first thing I said was, Jim, what about my water?

Krafjack had heard horror stories of people who could light their taps on fire, rivers that ran salty, and spills of hazardous chemicals -- all due to natural gas drilling. She decided to have her well water sampled before the drilling began, so she could monitor any changes.

Emily Krafjack decided to continue testing her well water as a natural gas well is constructed 400 feet from her house.Krafjack: We haven't had any problems with any of the water since they drilled. I was expecting some sediment or something during the drilling process. But we had nothing. Grens: Do you feel secure or will you continue to test? Krafjack: Oh, I'll continue to test. I know they're going to start fracking soon and so maybe after that we'd be looking at testing.

Fracking -- short for hydraulic fracturing -- sends a blast of sand and fluids in the well bore to crack open the shale and release gas deposits. The process is unnerving for some residents, because the fluid includes dozens of chemicals.

Theo Colborn is the president of the environmental research organization called The Endocrine Disruption Exchange, which has been an outspoken critic of gas industry drilling practices -- particularly, fracking.

Colborn: We've been trying to get a handle or an idea of what they're using. What are the products that are being used? What kinds of chemicals are they?

Colborn says she's been able to get the names of nearly 1,000 chemicals companies use in the process -- but almost half of those were not chemically identifiable.

Colborn: In other words, 43 precent of those names only provided a name on material data safety sheets...And industry is not telling us enough. Theo Colborn, president of The Endocrine Disruption Exchange, has been investigating chemicals used in hydraulic fracturing.The industry is becoming more transparent in disclosing fracking recipes, says Matt Pitzarella, a spokesman for Range Resources, one of the most active Marcellus Shale drillers. The company prides itself on having been the first to post well-by-well fracking recipes. Pitzarella admits that some ingredients are hazardous in concentrated form.

Pitzarella: Of those components that are considered hazardous in a concentrated form, our fluid makes up 0.04 percent of what goes into the well....At that level of dilution they pose no risk to human or animal health.

Pitzarella points out that fracking has been around in various forms for decades -- and it keeps getting safer, with fewer hazardous chemicals.

Pitzarella: If you look in Fort Worth in the Barnett Shale in Texas they have drilled 14,000 of these exact same wells in a 50 mile radius of the city of Fort Worth, and they have had no impacts on water, air quality.

There have been complaints from Texas residents that their water supply was affected.

The Environmental Protection Agency is soliciting input about research on fracking fluids. Previous work by the EPA was criticized as being biased toward the industry. EPA is still working out the details of this new study plan, but expects to have results in about two years.

Bryan Swistock at Penn State is leading a study to measure any impacts gas drilling may have on residents’ drinking water wells.Pennsylvania's Department of Environmental Protection is working to better protect water supplies; it has ramped up inspections and violations of unsafe truck drivers; limited the amount of pollutants drillers can discharge from their sites; and is working to improve well construction so there are no gas leaks.

DEP Secretary John Hanger:

Hanger: The industry is now reusing waste water and reducing the amount of water that they would dispose of in a river/stream because they face the great cost of cleaning it up before it goes into a river/stream.

Penn State has launched its own study on the water impacts of drilling, led by Bryan Swistock.

Swistock: There's a whole string for opportunities for problems. Not that they've been widespread, but there are certain places where there is a risk.

Swistock's team is intensively monitoring drinking water at 50 homes around Pennsylvania, each within 2,000 feet of a well site. He says many residents are concerned about fracking fluids seeping up from the shale. But that hasn't been the source of problems to date.

Swistock: The hydraulic fracturing has been done for a long time and has a relatively good track record. A lot of what we do see are human accidents and errors right around the well.

Spills or poor construction have led to chemicals getting into places they shouldn't. The other problem -- and perhaps the most infamous -- is gas migration. Badly sealed wells allow the gas to seep into aquifers close to the surface, and then into people's drinking water wells. Dimock, Pennsylvania in Susquehanna County had a number of cases of explosions and flammable taps.

In a year Swistock will have data on the water monitoring. While waiting for results, drilling will continue and so will people's concerns.

Shimer: They're scared. They know about Dimock. It frightens them and they never realized how much their water meant to them until this came along and they wish it wasn't here.

Kay Shimer, lab manager at Benchmark Analytics, says she’s taken hundreds of calls from residents concerned about their water.Kay Shimer is the laboratory manager at Benchmark Analytics in Sayer, Pennsylvania. The company analyzes water samples from residents and companies. Shimer has been flooded with calls from worried residents, asking what they should do when the gas trucks begin streaming by to well construction sites. She refers them to Penn State's recommendations: testing just before drilling begins, and then waiting for signs of change in the water -- like cloudiness or color -- before testing again.

Shimer: We tell people, take a cigarette lighter and try to ignite it. If it ignites, you have a problem.

Shimer says most of the analysis her company has done is pre-drilling. Only a few of the post-drilling samples have been contaminated with ethane or methane. But there have also been some surprises. One well had high methane levels before drilling started nearby.

Shimer: But apparently there was some drilling activity in the area they thought was too far away to affect them and apparently it wasn't.

Some people are waiting for the EPA's research to figure out of they want to lease their land for drilling. As gas company reps keep knocking on doors, many owners will have to choose before the data are in.