From May to December 2017, 48 environmental samples and six quality control samples were collected throughout the Upper Hudson and Central New York River Basins. Samples were collected from nine production wells and 11 domestic wells in the Upper Hudson River Basin, and 14 production wells and 14 domestic wells in the Central New York River Basin. Of the total wells sampled, 22 were completed in bedrock and 26 were completed in sand and gravel. Approximately 20 percent of samples were collected from wells that were previously sampled as in 2007 and 2012. Groundwater samples were collected prior to any treatment or filtration systems, from existing domestic and production wells equipped with permanently installed pumps.
Samples were collected and processed using standard USGS methods and were analyzed for 372 constituents including physicochemical properties, dissolved gases, major ions, nutrients, trace elements, pesticides, volatile organic compounds (VOCs), radiological activity, and indicator bacteria. All analytes are listed in the data release, along with the associated method detection and reporting limits, some of which changed over time. About 73 percent of constituents analyzed were not detected at concentrations greater than the method detection limit. Samples were analyzed at the USGS National Water Quality Laboratory (NWQL) in Denver, Colorado, and other certified laboratories following published methods.
Quality assurance and quality control samples were collected and assessed in each of the sampled basins. In the Upper Hudson River Basin, one replicate was collected at well SA1091, and in the Central New York River Basin, one replicate was collected at well OW1677, and both were analyzed for all constituents. Replicates analyzed for dissolved gases, radionuclides, and indicator bacteria were collected at well RE4784 of the Upper Hudson River Basin and well OT1821 of the Central New York River Basin. Field blanks analyzed for major ions, dissolved solids, nutrients, organic carbon, trace elements, pesticides, and VOCs were collected at well OT1821 and well RE4784. The VOC 1,2,4-Trimethylbenzene was detected in blank samples and most of the groundwater samples, and contamination is suspected from the scintillation liquid in the radon sampling kits. Due to the potential for contamination bias, results for 1,2,4-Trimethylbenzene are not included.
