This map displays predicted probability of a 12-digit Hydrologic Unit (HUC12) being at risk of violating the drinking water nitrate standard. Risk is defined as there being greater than a 50% chance of having a drinking water violation. Observed violations of the nitrate standard in public drinking water was used to make predictions across the conterminous United States. The data on nitrate violations comes from the EPA's Safe Drinking Water Information System (SDWIS) and the data used as predictor variables in the prediction models comes from EPA's StreamCat database. The original predictions were made at the National Hydrography Dataset (NHD) Catchment scale and summarized at the HUC12 scale and/or 300 m pixel scale. The maps show that 19% of the conterminous United States is at risk of groundwater sourced drinking violations, while 16% of the U.S. is at risk of nitrate violations from surface water sources. Regions with the highest risk of nitrate drinking violations from groundwater sources are found in the southwest, south central plains, parts of north west, mid-Atlantic. Surface water sourced nitrate violations have the greatest risk primarily in the southwest and south-central areas of the U.S. This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

This EnviroAtlas dataset summarizes several U.S. Geological Survey (USGS) water budget and surficial groundwater datasets by 12-digit HUC. It includes average rates of evapotranspiration, quick-flow runoff, effective recharge (which reflects the quantity of water available to replenish the groundwater table), and total recharge (which also includes an estimate for the recharge quantity that was subsequently intercepted by riparian vegetation and converted to evapotranspiration) based on the USGS' 800m water budget estimates for the Conterminous United States (CONUS) at long-term timescales for 2000-2013. These datasets were produced by Reitz et al. (https://doi.org/10.5066/F7PN93P0). It also includes modeled averages of depth to the water table, mean water transit time across the vadose zone (or unsaturated zone), shallow aquifer transmissivity, long term average soil water content of the unsaturated zone, and mean water residence time in the root zone, based on the USGS's MODFLOW-6 groundwater flow models. These models were driven by spatially-distributed recharge estimated by Reitz et al. using average water-budget information for 1985-2015 and calibrated against long-term average water levels in observation wells, as well as water-level estimates derived from perennial first-order streams and wetlands. The development of the model input and output files included in the USGS data release, as well as post-processing used to derive additional water-budget components also included in this data release, are documented in the Water Resources Research article (https://doi.org/10.1029/2019WR026724). This dataset was produced the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

This EnviroAtlas dataset summarizes several U.S. Geological Survey (USGS) water budget and surficial groundwater datasets by 12-digit HUC. It includes average rates of evapotranspiration, quick-flow runoff, effective recharge (which reflects the quantity of water available to replenish the groundwater table), and total recharge (which also includes an estimate for the recharge quantity that was subsequently intercepted by riparian vegetation and converted to evapotranspiration) based on the USGS' 800m water budget estimates for the Conterminous United States (CONUS) at long-term timescales for 2000-2013. These datasets were produced by Reitz et al. (https://doi.org/10.5066/F7PN93P0). It also includes modeled averages of depth to the water table, mean water transit time across the vadose zone (or unsaturated zone), shallow aquifer transmissivity, long term average soil water content of the unsaturated zone, and mean water residence time in the root zone, based on the USGS's MODFLOW-6 groundwater flow models. These models were driven by spatially-distributed recharge estimated by Reitz et al. using average water-budget information for 1985-2015 and calibrated against long-term average water levels in observation wells, as well as water-level estimates derived from perennial first-order streams and wetlands. The development of the model input and output files included in the USGS data release, as well as post-processing used to derive additional water-budget components also included in this data release, are documented in the Water Resources Research article (https://doi.org/10.1029/2019WR026724). This dataset was produced the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

This EnviroAtlas dataset contains information about 303(d) impairments by 12-digit HUC. It uses data that was originally compiled for the Watershed Index Online (WSIO) Version 2.4, released August 31, 2022. This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

This EnviroAtlas dataset contains information about 303(d) impairments by 12-digit HUC. It uses data that was originally compiled for the Watershed Index Online (WSIO) Version 2.4, released August 31, 2022. This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

This EnviroAtlas dataset includes a number of Discharge Monitoring Report (DMR) metrics summarized by watershed for a given year (https://echo.epa.gov/help/loading-tool/watershed-statistics-help). These metrics include the number of facilities and wastewater discharges located within watersheds according to the Integrated Compliance Information System National Pollutant Discharge Elimination System (ICIS-NPDES), to track the permit compliance and enforcement status of facilities regulated by the NPDES under the Clean Water Act (https://echo.epa.gov/tools/data-downloads/icis-npdes-download-summary). This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

This EnviroAtlas dataset includes a number of Discharge Monitoring Report (DMR) metrics summarized by watershed for a given year (https://echo.epa.gov/help/loading-tool/watershed-statistics-help). These metrics include the number of facilities and wastewater discharges located within watersheds according to the Integrated Compliance Information System National Pollutant Discharge Elimination System (ICIS-NPDES), to track the permit compliance and enforcement status of facilities regulated by the NPDES under the Clean Water Act (https://echo.epa.gov/tools/data-downloads/icis-npdes-download-summary). This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

This EnviroAtlas dataset depicts the total length of stream or river flowlines that have impairments submitted to the EPA by states under section 303(d) of the Clean Water Act. It also contains the total lengths of streams, rivers, and canals, total waterbody area, and stream density (stream length per area) from the US Geological Survey's high-resolution National Hydrography Dataset (NHD). This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

This EnviroAtlas dataset includes a number of Discharge Monitoring Report (DMR) metrics summarized by watershed for a given year (https://echo.epa.gov/help/loading-tool/watershed-statistics-help). These metrics include the number of facilities and wastewater discharges located within watersheds according to the Integrated Compliance Information System National Pollutant Discharge Elimination System (ICIS-NPDES), to track the permit compliance and enforcement status of facilities regulated by the NPDES under the Clean Water Act (https://echo.epa.gov/tools/data-downloads/icis-npdes-download-summary). This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).

This EnviroAtlas dataset includes a number of Discharge Monitoring Report (DMR) metrics summarized by watershed for a given year (https://echo.epa.gov/help/loading-tool/watershed-statistics-help). These metrics include the number of facilities and wastewater discharges located within watersheds according to the Integrated Compliance Information System National Pollutant Discharge Elimination System (ICIS-NPDES), to track the permit compliance and enforcement status of facilities regulated by the NPDES under the Clean Water Act (https://echo.epa.gov/tools/data-downloads/icis-npdes-download-summary). This dataset was produced by the US EPA to support research and online mapping activities related to EnviroAtlas. EnviroAtlas (https://www.epa.gov/enviroatlas) allows the user to interact with a web-based, easy-to-use, mapping application to view and analyze multiple ecosystem services for the contiguous United States. The dataset is available as downloadable data (https://edg.epa.gov/data/Public/ORD/EnviroAtlas) or as an EnviroAtlas map service. Additional descriptive information about each attribute in this dataset can be found in its associated EnviroAtlas Fact Sheet (https://www.epa.gov/enviroatlas/enviroatlas-fact-sheets).