| #D001 | | aquifer | An aquifer is an underground body of rock that contains and can transmit groundwater. | high |
| #D002 | | SWC | Source Water Collaboratives | high |
| #D003 | | SSA | Sole Source Aquifer | high |
| #D004 | | NLCD | National Land Cover Database | high |
| #D005 | | MRLC | Multi-Resolution Land Characteristics | high |
| #D006 | | PAD-US | Protected Areas Database of the United States | high |
| #D007 | | NPDES | National Pollutant Discharge Elimination System | high |
| #D008 | | RAD | Reach Address Database | high |
| #D009 | | WATERS | Watershed Assessment, Tracking & Environmental Results System | high |
| #D010 | | FRS | Facility Registry Service | high |
| #D011 | | FMCSA | Federal Motor Carrier Safety Administration | high |
| #D012 | | NTAD | National Transportation Atlas Database | high |
| #D013 | | GRTS | Grant Reporting and Tracking system | high |
| #D014 | | TMDL | Total Maximum Daily Load | high |
| #D015 | | WBD | Watershed Boundaries Dataset | high |
| #D016 | | NHD | National Hydrography Dataset | high |
| #D017 | | DWMAPS | Drinking Water Mapping Application to Protect Source Waters | high |
| #D018 | | 305(b) program | The 305(b) program provides assessed water data and assessed water features for river segments, lakes, and estuaries designated under Section 305(b) of the Clean Water Act. | high |
| #D019 | | 303(d) Listed Impaired Waters program | The 303(d) Listed Impaired Waters program system provides impaired water data and impaired water features reflecting river segments, lakes, and estuaries designated under Section 303(d) of the Clean Water Act. | high |
| #D020 | | source water collaboratives | local, state, and watershed-based partnerships working to protect sources of drinking water | high |
| #D021 | | CWA | Clean Water Act | high |
| #D022 | | USGS | United States Geological Survey | high |
| #D023 | | Aquifer Exemption | The EPA exempts aquifers if the aquifer does not currently serve as a source of drinking water and will not serve as a source of drinking water in the future, based on certain criteria. | high |