ESTABLISHING A BASELINE AND A FINGERPRINT OF GROUNDWATER CHEMISTRY PRIOR TO HIGH VOLUME HORIZONTAL GAS DRILLING IN OTSEGO COUNTY, NEW YORK

Groundwater, and specifically drinking water, in Otsego County NY is susceptible to changes in water chemistry due to proposed natural gas drilling of the Marcellus and Utica shale formations. Our study focuses on establishing a baseline of groundwater chemistry prior to drilling. We collected eighteen samples taken from residential wells within Otsego County from Summer 2010 to Fall 2011. Some of the wells were sampled repeatedly throughout the year. We had the samples analyzed for 61 major, minor, and trace elements with an inductively coupled plasma mass spectrometer at a commercial laboratory (Activation Laboratories Limited, Canada), of which 51 elements were detectable. We determined conductivity, temperature, and pH on site, and measured alkalinity and anions with a Hach portable spectrophotometer back in the lab. The most abundant constituents found in the groundwater were Ca, Si, Na, Mg, K; all of which exist at a median of 500 ppb or greater. Elements that vary the most based on the coefficient of variation include Cd, Zn, and U. The most abundant anion measured was chloride, concentrations of which ranged from 100 ppb to 32,300 ppb. Barium levels ranged from 1.6 ppb to 217 ppb. In addition to our data collection, we utilize published data on groundwater chemistry from the USGS for water wells scattered widely across the upper Susquehanna watershed in New York. Variations in water chemistry are possibly due to disparities in well location, depth and underlying bedrock. Cross correlations between the twenty most prevalent elements between wells yield a quantitative measure of similarity and diversity. We find that such variability is more a function of space than time, leading to the idea that water can be fingerprinted, and thus provide a well-constrained baseline for monitoring purposes.