Spatial analysis for identifying hotspots of EDC and PPCP sources for monitoring systems

This study utilized spatial analysis to identify hotspots for endocrine disrupting chemicals (EDCs), pharmaceuticals, and personal care products (PPCPs) using data from potential sources including wastewater treatment plants, National Pollutant Discharge Elimination System (NPDES)-permitted pollution sources, septic systems, and agricultural and grazing areas. The study area is Lake Mead, to which the return of treated effluent is one of the largest water reuse practices in the USA. Based on Getis-Ord's Gi* statistic, clusters of pollution sources were identified based on the values of each feature and its neighboring features. Spatial analysis was applied to evaluate the impact from point and nonpoint source pollution. The results of spatial statistical analyses were used to evaluate the existing sampling locations in Las Vegas Wash. The results indicated that sampling locations with highest concentrations of EDCs/PPCPs were close to the outlets of subbasins with high susceptibility to EDCs/PPCPs, which confirms the suitability of sampling locations.