BEDROCK LITHOLOGIC AND STRATIGRAPHIC INFLUENCES ON THE WATER QUALITY OF SPRINGS IN CAMERON AND MCKEAN COUNTIES, PENNSYLVANIA

Recent research conducted on springs during a routine mapping project led to interesting correlative relationships between the characteristic groundwater of springs and the bedrock formations they flow through. This spring study is to gain a better understanding of bedrock influence on groundwater chemistry in northwest Cameron County and southeast McKean County, Pennsylvania. During geologic mapping of the Norwich and Rich Valley 7.5-minute quadrangles, over 90 springs within the Pottsville Formation (Pp), Waverly Group (MDw), Catskill Formation (Dck), and Lock Haven Formation (Dlh) were inventoried and analyzed for yield, pH, specific conductance, and temperature. Twelve springs had additional laboratory analyses including alkalinity, hardness, sulfate, sulfide, chloride, bromide, mercury, and metals (arsenic, barium, calcium, iron, lead, potassium, magnesium, manganese, sodium, strontium, and vanadium). Water quality results were compared to bulk rock geochemistry and XRD mineralogy to identify unique lithologic properties in each formation and how they affect the water chemistry. General trends observed include acidic waters in the coal-bearing Pottsville Formation transitioning to slightly acidic to slightly alkaline waters by the time the groundwater has percolated to the Waverly Group/Catskill Formation contact; seasonal increases in specific conductance and pH during base-flow conditions in late summer/early autumn; and a groundwater temperature range of 4.5° C (late winter) to 15.5° C (late summer/early autumn). These studies provide groundwater characteristics by geologic formation in a dominantly rural community that depends on groundwater as a drinking water supply. The data from this study provide the private homeowner, well driller, land manager, and land developer information that can inform water-well design/siting, use of springs as a water source, and strategic placement of future infrastructure in the study area.