Occurrence and source identification of perfluoroalkyl acids (PFAAs) in the Metedeconk River Watershed, New Jersey.

The Brick Township Municipal Utilities Authority (BTMUA), which relies on the Metedeconk River as its primary source of water supply, initiated a perfluoroalkyl acid (PFAA) source trackdown study in collaboration with the New Jersey Department of Environmental Protection (NJDEP) after discovering that the concentration of one PFAA, perfluorooctanoic acid (PFOA), was elevated at their raw surface water intake. Water samples were collected over eight sampling events between September 2011 and July 2014. Samples included surface water, groundwater, stormwater, sanitary sewer water, and commercial/industrial process water. Each sample was analyzed for ten PFAAs. Results from a set of samples collected from the 80 km2 South Branch Metedeconk River watershed directed the focus of this study to a 7.5-km2 area of interest. Within this area, a high concentration of PFAA contamination was documented in a localized zone. Subsequent groundwater sampling led to the identification of a plume of groundwater contamination emanating from an industrial/business park. The suspected source of PFAA detected in the river and drinking water intake was identified to a small industrial facility that used materials containing PFOA. Groundwater PFOA concentrations as high as 70,000 ng/L were found in samples taken within 200 m of the parcel and surface water concentrations as high as 130 ng/L were observed in the river. While various PFAAs were detected in the samples, particularly in groundwater samples, PFOA was identified as the primary contaminant of concern with respect to the river and the BTMUA water supply.

The Likelihood of Coliform Bacteria in NJ Domestic Wells Based on Precipitation and Other Factors.

The influence of precipitation on coliform bacteria detection rates in domestic wells was investigated using data collected through the New Jersey Private Well Testing Act. Measured precipitation data from the National Weather Service (NWS) monitoring stations was compared to estimated data from the Multisensor Precipitation Estimate (MPE) in order to determine which source of data to include in the analyses. A strong concordance existed between these two precipitations datasets; therefore, MPE data was utilized as it is geographically more specific to individual wells. Statewide, 10 days of cumulative precipitation prior to testing was found to be an optimal period influencing the likelihood of coliform detections in wells. A logistic regression model was developed to predict the likelihood of coliform occurrence in wells from 10 days of cumulative precipitation data and other predictive variables including geology, season, coliform bacteria analysis method, pH, and nitrate concentration. Total coliform (TC) and fecal coliform or Escherichia coli (FC/EC) were detected more frequently when the preceding 10 days of cumulative precipitation exceeded 34.5 and 54 mm, respectively. Furthermore, the likelihood of coliform detection was highest in wells located in the bedrock region, during summer and autumn, analyzed with the enzyme substrate method, with pH between 5 and 6.99, and (for FC/EC but not TC) nitrate greater than 10 mg/L. Thus, the likelihood of coliform presence in domestic wells can be predicted from readily available environmental factors including timing and magnitude of precipitation, offering outreach opportunities and potential changes to coliform testing recommendations.

Seasonality of Coliform Bacteria Detection Rates in New Jersey Domestic Wells.

It is important that indicators of fecal pollution are reliable. Coliform bacteria are a commonly used indicator of fecal pollution. As other investigators have reported elsewhere, we observed a seasonal pattern of coliform bacteria detections in domestic wells in New Jersey. Examination of a statewide database of 10 years of water quality data from 93,447 samples, from 78,207 wells, generated during real estate transactions, revealed that coliform bacteria were detected in a higher proportion of wells during warm weather months. Further examination of the seasonal pattern of other data, including well water pH, precipitation, ground and surface water temperatures, surface water coliform bacteria concentrations, and vegetation, resulted in the hypothesis that these bacteria may be derived from nonfecal (or environmentally adapted) as well as fecal sources. We provide evidence that the coliform seasonality may be the result of seasonal changes in groundwater extraction volumes (and to a lesser extent precipitation), and temperature-driven changes in the concentration of surface or near-surface coliform sources. Nonfecal coliform sources may not indicate the presence of fecal wastes and hence the potential presence of pathogens, or do so in an inconsistent fashion. Additional research is needed to identify the sources of the coliforms detected in groundwater.

Coliform bacteria in New Jersey domestic wells: influence of geology, laboratory, and method.

Following passage of the New Jersey Private Well Testing Act, 50,800 domestic wells were tested between 2002 and 2007 for the presence of total coliform (TC) bacteria. Wells containing TC bacteria were further tested for either fecal coliform or Escherichia coli (FC/E. coli) bacteria. Analysis of the data, generated by 39 laboratories, revealed that the rate of coliform detections in groundwater (GW) was influenced by the laboratory and the method used, and also by geology. Based on one sample per well, TC and FC/E. coli were detected in wells located in bedrock 3 and 3.7 times more frequently, respectively, than in wells located in the unconsolidated strata of the Coastal Plain. In bedrock, detection rates were higher in sedimentary rock than in igneous or metamorphic rock. Ice-age glaciers also influenced detection rates, most likely by removing material in some areas and depositing thick layers of unconsolidated material in other areas. In bedrock, coliform bacteria were detected more often in wells with a pH of 3 to 6 than in wells with a pH of 7 to 10 whereas the reverse was true in the Coastal Plain. TC and FC/E. coli bacteria were detected in 33 and 9.5%, respectively, of sedimentary rock wells with pH 3 to 6. Conversely, for Coastal Plain wells with pH 3 to 6, detection rates were 4.4% for TC and 0.6% for FC/E. coli.