PITTSBURGH (AP) — A top official with the U.S. Environmental Protection Agency is optimistic that a nationwide project examining natural gas hydraulic fracturing and potential drinking water impacts will provide comprehensive guidelines to help scientists and the public identify the key issues to focus on. But the industry said past studies have already shown the process is safe.

Glenn Paulson, the EPA's science advisor, said Friday that a progress report on the study — mandated by Congress in 2010 — should be released before the end of the year, and a final report in 2014. He spoke at a University of Pittsburgh conference on health impacts of hydraulic fracturing, or fracking.

Paulson said the study of fracking and drinking water "is one of the most aggressive public outreach programs in EPA history." He said the progress report will show the "range and depth" of what EPA is looking at, and will be open to public comment.

"It will really be a lot for experts to chew on in their particular fields," Paulson said, noting that EPA is reaching out to geologists, academic experts, the industry, environmental groups, and even Indian tribes.

"I think the drinking water study is going to be useful to local governments, and state governments, too," Paulson said. He added that "a lot of people have their minds made up" about fracking, even though many aspects of research are still in the early stages.

Paulson said the Obama administration is providing enough support to study the issue. The EPA says in the project overview that natural gas "plays a key role in our nation's clean energy future" but that serious concerns have been raised about potential impacts to the environment and human health.

The fracking process has made it possible to tap into deep reserves of oil and gas. Large volumes of water, along with sand and hazardous chemicals, are injected underground to break rock apart and free the oil and gas. Contaminated wastewater from the process can leak from faulty well casings into aquifers, but it's often difficult to trace underground sources of pollution. Some studies also have shown air quality problems around gas wells, while others have indicated no problems.

Dan Alfaro, a spokesman for Energy in Depth, an industry group, said it believes the EPA study will show that gas drilling and fracking are safe.

"There have been numerous studies and a multitude of research on oil and natural gas extraction methods," Alfaro said. The EPA study "will confirm once again previous findings that current industry practices used in development are safe, responsible and effective means of extracting and producing our natural energy resources."

Environmental groups and some scientists say there hasn't been enough research on fracking. The industry and many federal and state officials say the practice is safe when done properly, and many rules on air pollution and disclosure of the chemicals used in fracking are being strengthened.

In Pennsylvania, the EPA study is focusing on water quality and quantity issues in Washington, Bradford and Susquehanna counties.

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  • In this file photo from Oct. 14, 2011, a drilling rig is seen in Springville, Pa. State regulators blamed faulty gas wells drilled for leaking methane into the groundwater in nearby Dimock, Pa. It was the first serious case of methane migration said to be related to the Pennsylvania Marcellus Shale gas field drilling boom. (AP Photo/Alex Brandon, FILE)

  • British police secure the area where demonstrators erected a mock fracking rig with a banner reading 'No fracking in the UK' in a protest against hydraulic fracturing for shale gas outside the Houses of Parliament in London on December 1, 2012. AFP PHOTO / JUSTIN TALLIS

  • SPRINGVILLE, PA - JANUARY 18: A truck with the natural gas industry, one of thousands that pass through the area daily, drives through the countryside to a hydraulic fracturing site on January 18, 2012 in Springville, Pennsylvania. (Photo by Spencer Platt/Getty Images)

  • SAN FRANCISCO, CA - MAY 30: Protestors stage a demonstration against fracking in California outside of the Hiram W. Johnson State Office Building on May 30, 2013 in San Francisco, California. Dozens of protesters with the group Californians Against Fracking staged a protest outside of California Gov. Jerry Brown's San Francisco offices demanding that Gov. Brown ban fracking in the state. (Photo by Justin Sullivan/Getty Images)

  • People demonstrate on August 3, 2013 in La Petite Brosse, near Jouarre, outside Paris, to protest against an exploratory oil shale drilling, considering that it opens the door to the exploration of shale gas in the Parisian Basin. Banner reads 'Stop gas and oil shale'. AFP PHOTO / PIERRE ANDRIEU

  • In this Nov. 26, 2012 photo, Steve Lipsky demonstrates how his well water ignites when he puts a flame to the flowing well spigot outside his family's home in rural Parker County near Weatherford, Texas. The U.S. Environmental Protection Agency had evidence a gas company's drilling operation contaminated Lipsky's drinking water with explosive methane, and possibly cancer-causing chemicals, but withdrew its enforcement action, leaving the family with no useable water supply, according to a report obtained by The Associated Press. The EPA's decision to roll back its initial claim that hydraulic fracturing, or “fracking,” operations had contaminated the water is the latest case in which the federal agency initially linked drilling to water contamination and then softened its position, drawing criticism from Republicans and industry officials who insisted they proved the agency was inefficient and too quick to draw conclusions. (AP Photo/LM Otero)

  • In this file photo of Jan. 17, 2013, Yoko Ono, left, and her son Sean Lennon visit a fracking site in Franklin Forks, Pa., during a bus tour of natural-gas drilling sites in northeastern Pennsylvania. Ono and Lennon have formed a group called “Artists Against Fracking,” which has become the main celebrity driven anti-fracking organization. (AP Photo/Richard Drew, File)

  • In this March 29, 2013 file photo, a worker checks a dipstick to check water levels and temperatures in a series of tanks at a hydraulic fracturing operation at a gas drilling site outside Rifle, Colorado. (AP Photo/Brennan Linsley)

  • In this March 29, 2013 file photo, a worker switches well heads during a short pause in the water pumping phase, at the site of a natural gas hydraulic fracturing and extraction operation outside Rifle, in western Colorado. (AP Photo/Brennan Linsley)

  • In this March 29, 2013 file photo, workers tend to a well head during a hydraulic fracturing operation at a gas well outside Rifle, in western Colorado. (AP Photo/Brennan Linsley)

  • Josh Fox, director of the anti-fracking, Oscar-nominated documentary “Gasland” testifies during a House Committee hearing on oil drilling, "fracking" legislation at the Illinois State Capitol Tuesday, May 21, 2013, in Springfield, Ill. (AP Photo/Seth Perlman)

  • This is a Thursday Aug. 15, 2013 image of the Cuadrilla exploration drilling site in Balcombe, southeast England. (AP Photo/Gareth Fuller/PA)

  • A child plays near a farmers' protest in an area where oil company Chevron plans to put a drilling rig exploring for shale gas in the south-eastern Polish village of Zurawlow on June 11, 2013. AFP PHOTO / JANEK SKARZYNSKI

  • Protesters hold a banner during a protest outside of the Momentive resin plant, Monday, July 8, 2013, in Morganton, N.C. Dozens of environmental activists blocked a chemical plant Monday to protest against the company's sale of products used in the natural gas drilling process called hydraulic fracturing, or fracking. (AP Photo/The News Herald, Mary Elizabeth Robertson)

  • A fracking rig exploring for shale gas of oil company Chevron on June 11, 2013 in a village of Ksiezomierz in south-eastern Poland. AFP PHOTO / JANEK SKARZYNSKI

  • People demonstrate on August 3, 2013 in La Petite Brosse, near Jouarre, outside Paris, to protest against an exploratory oil shale drilling, considering that it opens the door to the exploration of shale gas in the Parisian Basin. AFP PHOTO / PIERRE ANDRIEU

  • Opponents of hydraulic fracturing in New York state attend a news conference and rally against hydraulic fracturing, also known as fracking, on January 11, 2012 in New York City. (Photo by Spencer Platt/Getty Images)

  • Eric Weltman of Food & Water Watch attends a news conference and rally against hydraulic fracturing, also known as fracking, in New York State on January 11, 2012 in New York City. (Photo by Spencer Platt/Getty Images)

  • Opponents and supporters of gas-drilling, or fracking, walk into the last of four public hearings on proposed fracking regulations in upstate New York on November 30, 2011 in New York City. (Photo by Spencer Platt/Getty Images)

  • Engineers on the drilling platform of the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • Engineers at work on the drilling platform of the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • General views of the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • Engineers look at the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • A lump of shale rock on display at the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • Engineers on the drilling platform of the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • Engineers at work on the drilling platform of the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • Drill heads on display at the entrance to the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • An engineer displays a lump of shale rock at the Cuadrilla shale fracking facility on October 7, 2012 in Preston, Lancashire. (Photo by Matthew Lloyd/Getty Images)

  • Actor/director Mark Ruffalo (C) speaks at the Hydraulic Fracturing prevention press conference urging the protection of the drinking water source of 15 million Americans at Foley Square on April 25, 2011 in New York City. (Photo by D Dipasupil/Getty Images)

  • (L-R) Actor/director Mark Ruffalo, Denise Katzman, Wenonah Hauter, and Water Defense co-founder/campaign director Claire Sandberg attend the Hydraulic Fracturing prevention press conference urging the protection of the drinking water source of 15 million Americans at Foley Square on April 25, 2011 in New York City. (Photo by D Dipasupil/Getty Images)