The United States Geological Survey (USGS) recently released three publications that are relevant to natural gas extraction in the northeastern United States. Each study contributes important information to our understanding of the actual and potential environmental impacts of natural gas production.
One quantifies landscape changes due to natural gas extraction in Bradford and Washington Counties, Pennsylvania, between 2004 and 2010. The report concludes that shale gas and coalbed methane natural gas extraction practices “create potentially serious patterns of disturbance on the landscape.” The researchers examined landscape disturbance caused by well pads, roads, pipelines, impoundments, and other areas and activities such as processing plants, storage tanks, and staging areas. They found that the amount of landscape disturbance has increased, and that land cover changes due to natural gas extraction have been primarily to forest and agricultural lands. In particular, natural gas extraction activities increased forest fragmentation – creating more and smaller “patches” of forest – and resulted in an overall loss of forest, decreasing the amount of interior forest and increasing the amount of edge forest. Fragmentation, loss of interior forest, and increase in edge forest generally have detrimental impacts on flora and fauna.
The other two studies focus on documenting baseline groundwater quality in national parks in the northeast and in New York State.
The study in the national parks sought to determine baseline groundwater quality from 16 groundwater sources in nine national parks that overlie the Marcellus and Utica shales in New York, Pennsylvania, and West Virginia. The samples were analyzed for 53 constituents, including nutrients, major inorganic constituents, trace elements, chemical oxygen demand, radioactivity, and dissolved gases. For the most part, samples met national drinking water standards, although several samples exceeded secondary (aesthetic based) EPA standards for pH, total dissolved solids (TDS), sulfate, fluoride, sodium, iron, or manganese. One sample exceeded primary (health based) standards for arsenic, and eight samples exceeded the proposed maximum contaminant level (MCL) for Radon-222. One sample had a methane concentration considered to be above ambient background levels.
The report on New York sought to characterize dissolved methane concentrations in the groundwater of the state by compiling existing data. Some samples were from aquifer studies conducted in the late 1990s to characterize groundwater age, in which dissolved gas concentrations, including methane, were also determined. Other samples were from a collaborative project between the USGS and New York State Department of Environmental Conservation to assess groundwater quality in the major river basins of New York. The combined data set consists of methane concentrations in water wells from 239 locations in New York, spanning the years 1999 to 2011. Samples show that 47% of wells had no detectable methane and 91% of wells had methane concentrations below “action” levels (10mg/L). Only 2% of samples had methane concentrations greater than the level at which immediate action is recommended (28mg/L).
NRDC recently explained the importance of baseline groundwater testing in our comments on the Bureau of Land Management’s new proposed well stimulation rules. Although these studies aren’t substitutes for site-specific baseline testing, they contribute important information to our understanding of regional trends.
Good data documenting or related to environmental impacts of natural gas production are few and far between. These studies are welcome additions to a slowly growing but crucial body of knowledge.