Geospatial Assessment of Karst Spring Water Quality in Northeast Tennessee, USA

Abstract

Karst springs are an essential source of private water supply for about 10% of households in Tennessee. However, the water quality of these springs is unmonitored and unregulated even though many springs are highly productive yet vulnerable to contamination. This study assesses spatial patterns in the water quality of roadside springs in northeast Tennessee. Karst spring water samples collected from 50 springs were assessed using EPA Standard methods for pathogens, nutrients, radon, and physicochemical parameters. From statistical and spatial analyses, all but five samples contained E. coli, while all samples contained fecal coliform. High E. coli was spatially clustered (Local Moran’s I = 0.177, pseudo p-value = 0.012) in regions of high agricultural land use, resulting in a fecal contamination hot spot on the border of Washington and Sullivan Counties, Tennessee. Radon concentrations exceeded the 300 pCi/L proposed MCL in 29 (58%) of springs, with one spring in Unicoi County exceeding 1000 pCi/L. A radon hot spot was identified in northern Washington County (Local Moran’s I = 0.160, pseudo p-value = 0.014). Cokriging of E. coli with land use and radon with distance to mapped fault did not improve interpolation models for either parameter. Other parameters, including nitrate, pH, and total dissolved solids, were within recommended ranges for drinking water. This snapshot of spring water quality status identifies areas of poor spring water quality of which spring water users in the region should be aware, and establishes the need for longitudinal sampling of spring water quality in contamination hot spots.

Evaluation of karst spring water quality in northeast Tennessee using water quality indices

“…Notable agreement with the results produced in Fashina et al (2022) exists in sites of high fecal contamination and high radon concentration within northern Washington County-southern Sullivan County, which were rated "unfit for drinking" in BWQI. This agreement existed despite our noting that the high relative weight of parameters like DO, pH, and turbidity contributed more to the rating/assessment than E. coli or radon.…”

“…Water quality data (physicochemical, microbial, nutrient, and radioactive) were collected from 50 springs during May–June 2021 (Figure 1). Field methods and sampling protocol were fully described in (Fashina et al., 2022).…”

“…Recognizing that WQIs are developed for specific water quality objectives and working within the constraints of the water quality dataset described in (Fashina et al., 2022), two WQIs were selected for comparison: NSFWQI and BWQI. These are two of the most commonly used WQIs in the United States and they allow maximal use of the available data, unlike other rigid methods, hence their selection for the comparative analysis presented here.…”

“…Agricultural activities, especially livestock farming, dominate some parts of the study area and more predominantly in areas of the fecal contamination hotspot identified in Fashina et al (2022) which corresponds to areas of "unfit for drinking" water quality in the BWQI rating and "medium quality" in the NSFWQI rating. Therefore, we recommend that future research should consider inclusion of other water quality constituents like pesticides, other toxic organic compounds (from agro-allied chemicals) used for external parasite control in livestock, and water quality parameters suitable for drinking water-specific WQI models.…”