The Dunkard Creek disaster: summary of the ichthyofauna and the factors leading to a mining related fish kill in the Monongahela River Basin, West Virginia

Historically, the Monongahela River was regarded as one of the most polluted watersheds in the country due to acid mine drainage.   Mitigation of acid sources resulted in improved water quality and fish populations.  In October 2008, attention shifted to total dissolved solids (TDS) as drinking water had been periodically impaired by elevated levels of sulfates and chlorides.  In September 2009, a fish kill occurred in Dunkard Creek, a tributary of the Monongahela River, which straddles West Virginia and southwestern Pennsylvania for approximately 65 km.  Elevated stream conductivities (5,000-51,000 µS/cm) and chloride levels (>4,000 mg/l) were thought to blame.  In the ensuing weeks it was determined that golden algae, typically found in brackish waters, was the kill vector – moving in a downstream to upstream pattern.  Historic data from  resource agencies in West Virginia and Pennsylvania indicate that Dunkard Creek contained a limited fish population in the 1960s.  However, species richness and standing crop had increased between 1982 and 1998 by 29 % and 318%, respectively.  Surveys after the kill indicated the main channel was depauperate, while tributaries served as refugia.  Historic surveys will be summarized, samples made in the summer of 2010 reported, and the fish kill assessment discussed.