A broad assessment of 40 years of national water quality data was not enough to accurately gauge the possible impacts on watersheds of unconventional natural gas and oil development, according to a report by the U.S. Geological Survey (USGS).
"Results from this limited analysis suggest no consistent and widespread trends in surface water quality for SC [specific conductance] and CI [chloride] in areas with increasing unconventional oil and gas development, and highlight limitations of existing national databases for addressing questions regarding unconventional oil and gas development and water quality," according to the study, which was published by American Geophysical Union's Water Resources Research.
Researchers led by USGS scientist Zack Bowen used USGS and U.S. Environmental Protection Agency data sets to estimate trends in SC and CI in 16% of U.S watersheds with unconventional gas and oil resources. Analysis of the limited data found that CI decreased in about half the study areas and increased in about 40% of them, while SC decreased in more than half of the study areas and increased in about one-third of the rest.
But the researchers concluded that more data and research would be necessary to fully understand the potential risks to water quality associated with unconventional development.
"There are not enough data available to be able to assess potential effects of oil and gas development over large geographic areas," Bowen said.
There is no national water quality monitoring program focused on oil and gas development, the researchers said.
"Various federal and state agencies collect water quality data that often are related to regionally specific resource assessment or site-specific issues that require specific water quality data; however, these data may not include the necessary analytes, appropriate spatial distribution, or continuous sampling required to adequately assess national water quality questions," they said.