"AMLD [Abandoned Mine Lands Division] initiated a project to address acid mine drainage [AMD] in Aaron Run, a stream in Garrett County, Maryland that is listed on the state's 319(d) list of impaired waters because of AMD [acid mine drainage] impacts. In 2009, AMLD began the installation of three treatment systems to address the AMD that discharges to Aaron Run from a number of mine openings within the watershed. By August 31, 2011, all portions of the treatment system had been completed. AMLD requested that PPRP [Power Plant Research Program] collate and analyze the existing water quality data for the watershed and perform pre-treatment assessment of the data. The pre-treatment assessment presented herein provides a baseline for future evaluations of stream water quality once treatment systems are all operational and post-installation water quality data has been collected"--p. 1.