Guest editorial There is no denying that the oil and gas industry, as well as the agencies that regulate its activities, have significantly improved many aspects of environmental performance in recent years. Standards and practices have changed, in some cases drastically, leading to risk reductions in a number of areas. Despite this progress, there is always more to be done to identify and manage risks associated with oil and gas development. As industry continues to evolve through technical advances, so should leading practices and regulations. This is particularly important given that the broader public is increasingly aware of and concerned about potential impacts on the environment and their communities from development, especially where those impacts involve water. Fortunately, improved understanding of risks and newly emerging risk control options make continual improvement possible. Where should industry and its technical advisers concentrate at this juncture? A number of noteworthy, long-awaited reports on the environmental impacts of oil and gas development have been published over the past year or are awaiting publication. To a significant degree, these reports coalesce into a few major areas of concern, and endeavor to provide guidance on how governments and industry can achieve additional risk reductions to minimize or eliminate potential impacts on water. The Reports US Environmental Protection Agency (EPA), “Assessment of the Potential Impacts of Hydraulic Fracturing for Oil and Gas on Drinking Water Resources,” Draft, June 2015 The EPA report highlights potential vulnerabilities to drinking water and confirmed pollution events. Vulnerabilities include (1) inadequately cased or cemented wells resulting in belowground migration of gases and liquids, (2) inadequately treated waste water discharged into drinking water resources, and (3) spills of hydraulic fracturing fluids, flowback, and produced water. Given these vulnerabilities and knowledge gaps highlighted by EPA, industry should not take too much comfort in the widely reported conclusion that the EPA found no evidence of widespread, systemic impacts. California Council on Science and Technology (CCST), SB4 Commissioned Report for the California Natural Resources Agency, “An Independent Scientific Assessment of Well Stimulation in California,” July 2015 The CCST summary report contains an appendix summarizing the “most concerning risk issues” including (1) the number and toxicity of chemicals in hydraulic fracturing and acid stimulation fluids, (2) hydraulic fracturing in reservoirs with a long history of oil and gas production, (3) spills and leaks, (4) beneficial use of produced water, and (5) disposal of water in percolation pits.