This report presents the methodology and results for a study of surface-water quality of the Lycoming Creek watershed in north-central Pennsylvania during August 1–3, 2011. The study was done in cooperation with the Williamsport Municipal Water Authority and the Pennsylvania Department of Environmental Protection. Samples of stream water were collected from 31 sites in an area of exploration and production of natural gas from the Marcellus Shale – 5 sites on the main stem of Lycoming Creek and 26 sites on tributary streams. The samples provide a snapshot of the base-flow water-quality conditions, which helps document the spatial variability in water-quality and could be useful for assessing future changes.

The 272-square mile Lycoming Creek watershed is located within Lycoming, Tioga, and Sullivan Counties in north-central Pennsylvania. Lycoming Creek flows 37.5 miles to its confluence with the West Branch Susquehanna River in the city of Williamsport. A well field that supplies water for Williamsport captures some water that has infiltrated the streambed of Lycoming Creek. Because the stream provides a source of water to the well field, this study focused on the stream-water quality as it relates to drinking-water standards as opposed to aquatic life.

Surface-water samples collected at 20 sites by the U.S. Geological Survey and 11 sites by the Pennsylvania Department of Environmental Protection were analyzed by each agency for a suite of constituents that included major ions, trace metals, nutrients, and radiochemicals. None of the analytical results failed to meet standards set by the U.S. Environmental Protection Agency as maximum contaminant levels for drinking water.

Results of the sampling show the substantial spatial variability in base-flow water quality within the Lycoming Creek watershed caused by the interrelated effects of physiography, geology and land use. Dissolved-solids concentrations ranged from less than the laboratory reporting level of 12 milligrams per liter (mg/L) in Wolf Run, a pristine forested watershed, to 202 mg/L in Bottle Run, a watershed with more development near Williamsport. Concentrations of the major ions ranged over at least one order of magnitude; chloride had the largest range from 0.3 to 45.4 mg/L, with nine samples exceeding the natural background level of about 5 mg/L, most likely because of the application of deicing salt to roads. Trace constituents were even more variable, with concentrations for aluminum, cobalt, and manganese ranging over almost four orders of magnitude. Samples from Red Run and Dutchman Run, watersheds that experienced past coal mining activity, had concentrations of 11 metals that were significantly greater than in samples collected from other streams. Samples from Bottle Run, the tributary of Lycoming Creek nearest to Williamsport, contained elevated levels of chloride and boron, constituents associated with urban development.