HISTORIC AND CURRENT WATER QUALITY CHALLENGES IN PITTSBURGH: ACID MINE DRAINAGE TO COMBINED SEWER OVERFLOWS

Pittsburgh is inextricably linked to its three rivers. The Allegheny, Monongahela, and Ohio Rivers are transportation highways, drinking water sources, and ecological habitat. However, Pittsburgh’s industrialization has left a substantial environmental legacy and continues to have an impact on modern riverine water quality. Extensive coal mining from the 1700s to mid 1900s produced acid mine drainage (AMD) which polluted Pittsburgh’s rivers with acidity and metals. Additionally, rapid industrialization during the 1800s led to the development of combined sewer systems that carried both sewage and stormwater to Pittsburgh’s rivers. Since the 1950’s, regulation of the mining industry, water treatment, land reclamation, and natural attenuation have improved water quality in Pittsburgh to neutral pH and low metal concentrations. However, overflows from the city’s combined sewers remain a major water quality, and legal, challenge.

Pittsburgh’s topography, geology, and climate make it uniquely challenging to address contamination at the source and to stop contamination from reaching the rivers. Here, we discuss legacy and current water quality challenges facing the Pittsburgh area and how these challenges are being addressed. We analyzed current and historic data to track changes in water quality from different pollution sources. Pittsburgh’s water quality has greatly improved since the mid-1900’s, but there are still pollutants (i.e. combined sewer overflows) entering rivers and impacting human and ecological health.