CHARLESTON, W.Va. -- Researchers have begun to identify ways that wastewater and runoff from the natural gas production boom in the Marcellus Shale region is making its way into area rivers and streams.
A new study released this week documents increases in mud and silt downstream from gas drilling and production operations and higher levels of another key pollutant downstream from water treatment plants that handle Marcellus wastes.
The study, published in the Proceedings of the National Academy of Sciences, compared the results of more than 20,000 surface water monitoring reports with the locations of 5,000 wells across the gas-producing areas of Pennsylvania.
Researchers found a 10 percent increase in chlorides concentrations for every 1.5 wastewater treatment facilities located upstream. They found a 5 percent increase in total suspended solids for every additional 18 well pads upstream.
"These are not dramatic changes that they found, but they're not inconsequential either," said Duke University biologist Robert Jackson, who has studied gas-production impacts, but was not involved in the new research.
The study did not look at potential impacts on groundwater supplies -- a matter of much public concern and scientific debate. And it did not look for increases in any other toxic chemicals that might be discharged from gas production. But the study did confirm some previous findings about the drilling boom's effects on streams and rivers.
"The nature of surface water contamination from shale gas development considered here is qualitatively different from the groundwater concerns explored in the literature," says the study, written by Sheila Olmstead and others from the Washington, D.C., think tank Resources for the Future. "Although groundwater concerns may have primarily to do with contamination directly from wellbores or shale formations, surface water concerns may have primarily to do with off-site waste treatment and above-ground management."