EPA conducted independent research resulting in over 25 peer-reviewed research papers and journal articles. This research supports the final assessment. 

Analysis of Existing Data

• EPA Analysis of FracFocus 1.0 Data
• "Review of State and Industry Spill Data: Characterization of Hydraulic Fracturing-Related Spills"
  Burden et al. EPA Report. May 2015.
• Review of Well Operator Files
  • ​Well Design and Construction
  • Hydraulic Fracturing Operations

Case Studies

• Case Studies for EPA's Hydraulic Fracturing Study
  • ​Raton Basin, Colorado
  • Killdeer, North Dakota
  • Northeastern Pennsylvania
  • Southwestern Pennsylvania
  • Wise County, Texas

Laboratory Studies

• “Characterization of liquid chromatography-tandem mass spectrometry method for the determination of acrylamide in complex environmental samples”
  Patrick DeArmond and Amanda DiGoregorio. Analytical and Bioanalytical Chemistry. May 2013.
• “Rapid liquid chromatography–tandem mass spectrometry-based method for the analysis of alcohol ethoxylates and alkylphenol ethoxylates in environmental samples”
  Patrick DeArmond and Amanda DiGoregorio. Journal of Chromatography A. August 2013.
• "The Verification of a Method for Detecting and Quantifying Diethylene Glycol, Triethylene Glycol, Tetraethylene Glycol, 2-Butoxyethanol and 2-Methoxyethanol in Ground and Surface Waters"
  Brian A. Schumacher and Lawrence Zintek. EPA Report. July 2014.
• "Development of Rapid Radiochemical Method for Gross Alpha and Gross Beta Activity Concentration in Flowback and Produced Waters from Hydraulic Fracturing Operations"
  Schumacher et al. EPA Report. July 2014.        

• "Sources Contributing Inorganic Species to Drinking Water Intakes During Low Flow Conditions on the Allegheny River in Western Pennsylvania"
  Norris et al. EPA Report. May 2015.                                        

Scenario Evaluations

• “Modeling of fault reactivation and induced seismicity during hydraulic fracturing of shale gas reservoirs” 
  Rutqvist et al. Journal of Petroleum Science and Engineering. July 2013.
• “Development of the T+M coupled flow-geomechanical simulator to describe fracture propagation and coupled flow-thermal-geomechanical processes in tight/shale gas systems”
  Jihoon Kim and George Moridis. Computers and Geosciences. October 2013.
• “The RealGas and RealGasH2O options of the TOUGH+ code for the simulation of coupled fluid and heat flow in tight/shale gas systems”  
  George Moridis and Craig M. Freeman. Computers and Geosciences. April 2014.
• "MeshVoro: A three-dimensional Voronoi mesh building tool for the TOUGH family of codes"
  Freeman et al. Computers and Geosciences. September 2014.
• "Gas Flow Tightly Coupled to Elastoplastic Geomechanics for Tight- and Shale-Gas Reservoirs: Material Failure and Enhanced Permeability"
  Jihoon Kim and George Moridis. Society of Petroleum Engineers. December 2014.
• "Modeling of fault activation and seismicity by injection directly into a fault zone associated with hydraulic fracturing of shale-gas reservoirs"
  Rutqvist et al. Journal of Petroleum Science and Engineering. March 2015.
• "Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface ground water: background, base cases, shallow reservoirs, short-term gas and water transport"
  Reagan et al. Water Resources Research. April 2015.
• "Numerical analysis of fracture propagation during hydraulic fracturing operations in shale gas systems"
  Jihoon Kim and George Moridis. International Journal of Rock Mechanics and Mining Sciences. June 2015.
• "Case Study Analysis of the Impacts of Water Acquisition for Hydraulic Fracturing on Local Water Availability"
  Sullivan et al. EPA Report. May 2015.
• "Scenario Analysis of the Impact on Drinking Water Intakes from Bromide in the Discharge of Treated Oil and Gas Wastewater"
  Weaver, J., Xu, J., and Mravik, S. Journal of Environmental Engineering. August 2016.
• "Investigation of possible wellbore cement failures during hydraulic fracturing operations"
  Kim, Jihoon, Moridis, George J., Martinez, Eduardo R. Journal of Petroleum Science and Engineering. February 2016. 

Toxicity Studies

• "Overview of Chronic Oral Toxicity Values for Chemicals Present in Hydraulic Fracturing Fluids, Flowback and Produced Waters"
  Yost, et al. Environmental Science and Technology. April 2016.
• "Estimating the Potential Toxicity of Chemicals Associated with Hydraulic Fracturing Operations Using Quantitative Structure-Activity Relationship Modeling"
  Yost, et al. Environmental Science and Technology. May 2016