Energy usage in the United States has increased by more than 50 percent in the last half-century, and a similar increase is projected by 2030. In many places, the impacts of energy development are considered only on a project-by-project basis without accounting for their collective effects on fresh water and other natural systems that ensure the health of people and wildlife.

A new study by Nature Conservancy scientists published today in the journal PLOS ONE, is the first one to examine the potential environmental impacts of shale gas and wind development across the entire Marcellus shale play, a mammoth gas field in Central Appalachia that underlies portions of New York, Pennsylvania, Ohio, Maryland, Virginia and West Virginia.

The Marcellus shale gas play is one of the most active shale gas developments in the world and falls within the Central Appalachian Forest—a national and global hotspot for natural diversity and a source of drinking water for more than 22 million people in several of the largest metropolitan areas in the United States (e.g. New York City, Pittsburgh, Philadelphia and Washington, DC).

“Studies such as this provide the tools to evaluate areas where cumulative impacts may be the highest, enabling decision-makers to focus on how those impacts may be minimized,” said Jeffrey Evans, lead author of the manuscript and Senior Landscape Ecologist for The Nature Conservancy’s Development by Design global program.

The study uses The Conservancy’s Development by Design methodology, taking a proactive, big picture approach to identify where conflicts could occur between expected development and important natural resources.

The study found the following:

• The impacts from energy development in the Central Appalachians could lead to a decrease in watershed condition and potentially affect the quality of surface water (including drinking water resources) for up to 22 million people.
• According to a U.S. Forest Service report, watersheds in the region are among the most important in the country due to the amount of drinking water they produce, and the study projects that energy development in the region will disproportionally take place in watersheds identified in that report as high-value watersheds.
• 36% of the predicted energy expansion in the study area is expected to occur in watersheds that are among the top 25% nationally in terms of water importance, also representing intact forests with high biodiversity.
• In comparison to wind, shale gas development will result in significantly more land use change in the Central Appalachians region—causing significant conversion of natural vegetation and deforestation. Wind development, however, will have a disproportionate impact on mountain ridge habitats.
• The study predicts up to 106,004 new gas wells and 10,798 new wind turbines, resulting in up to 1,490,732 acres (an area larger than the state of Delaware), of impervious surfaces due to development of roads, well pads and pipelines and upwards of 1,224,053 acres of affected forest.
• Unlike traditional gas development, horizontal drilling shale gas wells allow for more flexibility in where well pads and infrastructure can be placed. This flexibility provides a tremendous opportunity to help avoid or minimize the impacts to natural habitats (e.g. if well density achieves 8 wells per pad, forest impacts are reduced by 59%).

The paper illustrates that it is the cumulative impacts to land and water that pose the greatest challenge for energy expansion. Despite the potential for significant cumulative impacts, there are no safeguards in place to assess or even consider these potential impacts in the decisions made about development siting.

“Our analysis illustrates that you do not need to wait until development occurs to estimate environmental impacts. By using science-based scenario modeling, political and corporate decision makers can take a proactive approach to development planning that avoids impacts before they create significant problems,” said Joe Kiesecker, co-author and a Conservancy’s Lead Scientist and Development by Design Director.

The Nature Conservancy is also working on a broader Appalachians-wide analysis that will evaluate the potential effects of natural gas, coal, and wind development on the region’s forests and natural resources over the next 20 years. This analysis will help actors in the public, private, and non-profit sectors to consider the cumulative effects of energy development on nature and natural resources across the entire region, and to take those impacts into account when planning and implementing development projects.

News release by The Nature Conservancy.