MITRE WaterSHEDs PFAS vulnerability model output for Upper Colorado River Basin at 1 km, 9 km, and 100 km hexagonal tessellations

Per- and polyfluoroalkyl substances (PFAS) in the aquatic environment present a water resource management challenge, in part due to the geospatial distribution of presumptive sources and their connections to the hydrological network. MITRE developed a geospatial model called Water Sensing and Hydrology for Environmental Decision Support (WaterSHEDS) that assigns stream-vulnerability scores based on a limited number of presumptive PFAS sources and the hydrologic network from NHDPlus High Resolution. This model is intended to inform decisions on where to sample for PFAS based on upstream presumptive hazard sources. Presumptive PFAS sources within the watershed were assigned relative weights based on their industries. The presence of presumptive sources upstream from each flowline, their relative industry weighting, and distance from the flowline were used to estimate a vulnerability score for each stream reach. A low vulnerability score indicates the absence of presumptive PFAS sources in the contributing catchment, and higher score indicates the presence of many high-weighted potential sources near the stream segment of interest. These vulnerability scores were aggregated into 1 km, 9 km, and 100 km hexagonal tessellations. The WaterSHEDS model is intended to be flexible in the number and type of hazard data sources used, and in how the attributes within the hazard sources and the USGS hydrology data layers are used to calculate an integrated vulnerability.