Evaluation of Watershed-Scale Acid Mine Drainage Treatment in the Muddy Creek Watershed, West Virginia

Abstract Acid mine drainage (AMD) from historic, unregulated mining in the eastern U.S. Appalachian Coal Basin has impaired thousands of stream km. Federal and state regulations enacted in 1977 distinguished between these unregulated or abandoned mine lands (AML) and post-1977 or regulated discharges. The regulations also required high standards of treatment for regulated, point-source discharges. Untreated AML discharges often contribute over 80% of the AMD load to watersheds, resulting in ongoing impairment despite major investments in the treatment of regulated discharges. This project evaluated watershed-scale restoration (WSR) with the objective of restoring the designated uses to a given watershed by treating AMD from both AML and regulated discharges based on their load contribution and the cost per recovered stream length. Results were compared to pre-project impairment levels and costs. Despite higher capital costs for WSR, lower operating costs resulted in net savings over the point source treatment strategy. Treatment of only regulated discharges was found to be more expensive over the long term and resulted in the recovery of zero stream km. Managing AMD treatment at a watershed scale rather than at regulated discharges only may produce superior economics in similar watersheds. Furthermore, restoration is achieved more quickly, with more stream km recovered.