PREPARING FOR MARCELLUS SHALE DRILLING: ESTABLISHING BASELINE WATER QUALITY AT FIDDLE LAKE, SUSQUEHANNA COUNTY, PENNSYLVANIA

Flowback fluids associated with hydraulic fracturing extraction methods are a potential source of contamination for shallow aquifers. This study investigates whether a single, certified multiparameter water test is sufficient for establishing baseline water quality for private drinking water wells from which possible future contamination by flowback waters could be recognized. A statistical analysis of repeated measurements of well water from 32 houses around Fiddle Lake, PA shows greater between house variability for dissolved species in ground water than within house variability for major ions over time, due to different contributions by mineral weathering and deicing agents to ground water in the watershed. Comparison of a subset of these houses that had certified water tests against repeated measurements showed a significant difference (p<0.05) for 4 out of 13 parameters, but this resulted in part to one house having a certified test with analytical errors. After removing this house from the statistical model, the repeated measurements only showed a significant difference from the certified tests for 2 out of 13 parameters: Mg²⁺ and Cl^-. Aside from potential laboratory errors, the results lend confidence that a single certified test can represent a baseline chemistry, particularly for trace metals that do not have a significant source within the watershed. Follow-up certified tests will assist with establishing a geochemical picture, particularly if the well already receives nonpoint source pollution. Certified tests should include multiple parameters so potential contamination from flowback waters can be distinguished from other sources of nonpoint source pollution in the watershed.