NMED is mapping areas where waters of the state may be vulnerable to contamination from septic tank discharges, and where stricter standards may be imposed. Aquifer sensitivity maps prepared for NMED by Lee Wilson and Associates in 1989 have been digitized and are a data layer in the online Liquid Waste Geographic Information System (GIS). The tab for GIS data layers is near the upper right corner, the buttons for zoom in/out and other functions are on the left, aquifer sensitivity maps are under Geology/Landcover. The Lee Wilson maps are being updated and modified to include current depth-to-ground-water information, as well as areas of karst and fractured bedrock, known contamination sites, and gaining streams. These maps also can be downloaded as bitmap and gif files (Table 1). The maps contain color-coded groundwater areas based on depth to water and naturally occurring, background, total dissolved solids (TDS) as explained in Table 2. Areas with ground water less than 100 feet deep, and with 2000 mg/L or less TDS, are mapped in red. Other areas of concern based on karst or fractured bedrock, known ground-water contamination, and gaining streams impacted by septic tank effluent, are also being mapped.
