DEVELOPMENT OF A GEOGRAPHIC INFORMATION SYSTEMS METHODOLOGY FOR THE PUBLIC DRINKING WATER SOURCE WATER ASSESSMENT PROGRAM IN TENNESSEE

The Tennessee Department of Environment and Conservation (TDEC) is responsible for administering Tennessee’s Source Water Assessment Program (SWAP), as required by the Safe Drinking Water Act. The goal of the SWAP is to assess the vulnerability of public supply drinking-water from both surface water and groundwater sources to potential contamination. In 2021, the U.S. Geological Survey (USGS) began a program in cooperation with TDEC to develop a geographic information system (GIS)-based decision support system (DSS) that systematically completes source water assessments following the standards set forth in Tennessee’s rules for the more than 1,380 drinking-water sources across the State. A primary goal of the tool is to provide TDEC with a consistent foundation for assessing public drinking water, which communities and water managers can then build on using local knowledge and site-specific information. The DSS is built as an ESRI ArcGIS Pro toolbox and uses Python programming language and LaTeX Document Preparation System to generate summary source water assessment reports. TDEC can execute the DSS from an ArcGIS Pro session to delineate protection zones around public supply sources using NHDplus water body data and source locations provided by TDEC, collate and map the potential contaminant sources in protection zones, consume digital datasets that can be used to rate the susceptibility of the water sources to potential contaminants, and generate a consistent report that summarizes the findings. The susceptibility of a public water source to contamination is assessed using publicly available GIS datasets of environmental conditions (such as soils, climate, geology) and TDEC-managed datasets (such as location of potential contaminant sources).