GEOCHEMICAL BASELINE STUDY OF TEN STREAM SITES IN THE BRIAR CREEK WATERSHED (COLUMBIA COUNTY, PA) IN RELATION TO LAND USE AND GEOLOGY OF THE SURROUNDING AREA

Water samples were collected from 10 sites in the Briar Creek watershed on a biweekly basis from October 2011 to August 2012. Our data collection of chemistry and geology of the area is in support of a study by the Briar Creek Association for Watershed Solutions (BCAWS) to characterize conditions, in order that they may establish a conservation plan for the Briar Creek watershed. In situ analyses of the samples included pH, temperature, dissolved oxygen, and conductivity. Turbidity was measured on site on unfiltered samples. Alkalinity and acidity were measured within six hours of collection on filtered samples. Samples, both filtered and unfiltered, were preserved for later laboratory analyses for simple cations and anions by ion chromatography and selected heavy metals by inductively-coupled plasma optical emission spectroscopy. Samples from two of the sites (one near a trailer park and rail trail and the other the most downstream site near the confluence of Briar Creek with the Susquehanna River) consistently showed higher values for iron than those from the remaining sites. Samples from the site near the trailer park and rail trail were also consistently higher in acidity, alkalinity, conductivity and dissolved barium, manganese, bromide, nitrate, sulfate, potassium, magnesium, and calcium. Samples from a third site, in headwaters exiting a wooded area, were consistently lower in concentration for most of those same species, while the samples from downstream of that site were higher in those species, particularly calcium, magnesium and especially nitrate, an indicator of farming influences. We noticed coordinated higher and lower concentrations in many species over time. One possible cause of these coordinated variations would be stream discharge, which we are currently investigating. We hope that with the chemical data available from our closely spaced sampling/analyses, we will be able to pin down the influence of local geology and land use on the various parts of the watershed, helping BCAWS to better develop their management plan.