By Kyle Ferrar, MPH – EOH Doctoral Student, University of Pittsburgh GSPH
Wastewater discharges are regulated through national pollutant discharge elimination system (NPDES) permits, and are based on the concept “the solution to pollution is dilution.” However, what happens when the diluting capacity of a river diminishes? If the natural gas industry will be producing 20 million gallons per day (MGD) of wastewater in 2011, but only retrieves 20% to 70% of the water used to drill and hydrofracture a well, over 28.5 to 100 MGD must be withdrawn from water resources1.
Water withdrawals for the natural gas industry are permitted through the Pennsylvania Department of Environmental Protection (PA DEP) with the approval of the Department of Conservation and Natural Resources (DCNR). As water is withdrawn, the volumes of stream flow decrease. Water withdrawals must be conducted responsibly, so that the volumes of stream flow are not impacted. Decreasing flow decreases the assimilative capacity of waterways to dilute pollution, such as TDS. In the late summer and fall, lack of precipitation causes drought conditions, and accounts for the lowest flow periods each year. But in 2008 through 2010, flow in parts of the Monongahela River have been less than half than what they are typically, at this time of the year, according to the Army Corps of Engineers2.
Figure 1. Permitted surface water withdrawals in Pennsylvania are shown on the map, active as of April 2, 2010.
Figure 1 shows the permitted water withdrawals in Pennsylvania for commercial, industrial, and agricultural use, as well as the permitted water withdrawals for the oil and natural gas industry. There is a multitude of groups that rely on water withdrawals for their livelihood, including the oil and gas industry, labeled as red stars. The capacity of river flow to dilute pollutants to safe levels also depends on river flow, and has precise limits. The current assimilative capacity for pollution and TDS in the Monongahela River is showing signs of saturation, and is characteristically oversaturated during the dry season. Monongahela River communities are already urged to rely on bottled water rather than their own municipal tap water, for certain periods of the year. Therefore, at the current rate of natural gas industry water withdrawals, there is no longer any room left for further economic development of water resources in other sectors of industry within the Monongahela River basin, if public health is to be conserved.
The current water management practices of the natural gas industry during the regional dry season are likely to have contributed to higher TDS concentration in the Monongahela River. New regulations for treatment and discharge of wastewater are designed so that the wastewater does not result in a severe impact, but the issue of mediating sustainable withdrawals has not been addressed. The majority of the pollution in the Monongahela River is still suspected to be caused by issues of legacy pollution, such as extensive acid mine drainage within the watershed3. On the other hand, the water withdrawals in the Monongahela River watershed are potentially causing a cumulative impact on flow volume in the river that magnifies all forms of pollution by increasing the pollutant concentrations. Much more research needs to be conducted on this issue, to ensure safe and sustainable permitting practices for water withdrawals.
- Penn State University, College of Agricultural Sciences, Agricultural Research and Cooperative Extension. 2010. Shaping proposed changes to Pennsylvania’s total dissolved solids standard, a guide to the proposal and the commenting process.
- Puko, Tim. Silty Salty Monongahela River at risk from pollutants. Tuesday August 24, 2010. Pittsburgh Tribune Review.
- Anderson, Robert M. Beer, Kevin M. Buckwalter, Theodore F. Clark, Mary E. McAuley Steven D. Sams, James I. Williams, Donald R. 2000. Water Quality in the Allegheny and Monongahela River Basins. USGS circular 1202.