Natural land cover can remove pollutants from runoff water by slowing water flow and physically trapping suspended particles. We identified natural land cover in the Southeast US potentially contributing to water purification due to its location in the flowpath between sources of nonpoint-source pollution and waterways.

Natural land cover can remove pollutants from runoff water by slowing water flow and physically trapping suspended particles. We identified natural land cover in the Southeast US potentially contributing to water purification due to its location in the flowpath between sources of nonpoint-source pollution and waterways. Version 2.0 provides an update to the previous version with the inclusion of data from 2013, 2016, and 2019.

Natural land cover can remove pollutants from runoff water by slowing water flow and physically trapping suspended particles. We identified natural land cover in the Southeast US potentially contributing to water purification due to its location in the flowpath between sources of nonpoint-source pollution and waterways.

Natural land cover can remove pollutants from runoff water by slowing water flow and physically trapping suspended particles. We identified natural land cover in the Southeast US potentially contributing to water purification due to its location in the flowpath between sources of nonpoint-source pollution and waterways. Version 2.0 provides an update to the previous version with the inclusion of data from 2013, 2016, and 2019.

The U.S. Geological Survey (USGS) developed a spatial water-quality model called SPAtially Referenced Regressions On Watershed attributes (SPARROW) to estimate the major sources and environmental factors that affect the long-term supply, transport, and fate of contaminants in the Nation’s streams. The SPARROW model relates in-stream water-quality data to spatially referenced characteristics of watersheds, including contaminant sources and factors influencing terrestrial and aquatic transport. Based on SPARROW modeling, one of the main nutrient sources to streams is point-source facilities such as municipal waste-water treatment plants that discharge directly to streams. This dataset was developed to assist with SPARROW models developed to assess supply, transport and fate of total nitrogen and phosphorous in streams of the conterminous United States (2012). This dataset documents discharge information from point sources in the conterminous United States and was obtained from the EPA Integrated Compliance Information System (ICIS) and Permit Compliance System (PCS). When available, nutrient concentrations were used to calculate point source loads. However, in many cases measured concentration data were not available in the ICIS or PCS data base and so “typical pollutant concentrations” (TPC’s) were developed using data from similar facilities. A new method for calculating TPC’s was implemented that allows varying amounts of nutrient concentration data and/or varying numbers of facilities to determine TPC’s. This dataset contains the EPA facility, flow, and concentration data and all updates to the data, along with the TPC tables and resultant total nitrogen and phosphorous loads calculated from the input datasets.

The U.S. Geological Survey (USGS) developed a spatial water-quality model called SPAtially Referenced Regressions On Watershed attributes (SPARROW) to estimate the major sources and environmental factors that affect the long-term supply, transport, and fate of contaminants in the Nation’s streams. The SPARROW model relates in-stream water-quality data to spatially referenced characteristics of watersheds, including contaminant sources and factors influencing terrestrial and aquatic transport. Based on SPARROW modeling, one of the main nutrient sources to streams is point-source facilities such as municipal waste-water treatment plants that discharge directly to streams. This dataset was developed to assist with SPARROW models developed to assess supply, transport and fate of total nitrogen and phosphorous in streams of the conterminous United States (2012). This dataset documents discharge information from point sources in the conterminous United States and was obtained from the EPA Integrated Compliance Information System (ICIS) and Permit Compliance System (PCS). When available, nutrient concentrations were used to calculate point source loads. However, in many cases measured concentration data were not available in the ICIS or PCS data base and so “typical pollutant concentrations” (TPC’s) were developed using data from similar facilities. A new method for calculating TPC’s was implemented that allows varying amounts of nutrient concentration data and/or varying numbers of facilities to determine TPC’s. This dataset contains the EPA facility, flow, and concentration data and all updates to the data, along with the TPC tables and resultant total nitrogen and phosphorous loads calculated from the input datasets.

Of the approximately 6.6 million people living in the Mississippi embayment (MISE) region in the central United States, approximately 65 percent rely on groundwater for their drinking water (Dieter, Linsey, and others, 2017). Regional assessments of water quality in principal aquifer systems provide context for the long-term availability of these water resources for drinking-water supplies. To assess the current (2018) status of water quality in MISE in relation to drinking water supplies, groundwater withdrawal zones used for domestic and public supply were modeled using available groundwater well and hydrogeologic framework data. Three dimensional surfaces were modeled to map the depth zones at which groundwater is withdrawn for drinking water. These surfaces will be used to model groundwater quality as part of the U.S. Geological Survey National Water Quality Assessment project’s intensive principal aquifer analysis. The MISE region includes two principal aquifer systems: the surficial aquifer system, which is dominated by the Quaternary Mississippi River Valley Alluvial aquifer (MRVA), and the Mississippi embayment aquifer system, which includes deeper Tertiary aquifers and confining units. Based on the distribution of groundwater use for drinking water, the modeling effort is focused on MRVA and two hydrogeologic units from the deeper system, including the middle Claiborne aquifer (MCAQ) and lower Claiborne aquifer (LCAQ). The MRVA is a surficial, unconfined to semi-confined, highly productive aquifer used mostly for irrigation, with a lesser amount of groundwater use for public supply and domestic self-supply (Clark and others, 2011; Maupin and Barber, 2005). The median thickness of the MRVA is about 130 feet (ft) but it can be as much as 290 ft thick (Hart and others, 2008). The MCAQ is confined where overlain by the Middle Claiborne confining unit and is used dominantly for public supply. Domestic self-supply occurs along outcrop areas where the unit is shallower or crops out. The unit consists mostly of the Sparta Sand, but north of approximately the 35th parallel (near the border between Tennessee and Mississippi), the underlying lower Claiborne confining unit (LCCU) undergoes a facies change and the Memphis Sand is included in the MCAQ (Hosman and Weiss, 1991). The MCAQ has a median thickness of about 805 ft, but it can be as much as 1,890 ft thick (Hart and others, 2008). Although not as regionally important as MRVA or MCAQ, domestic and public supply wells withdraw groundwater from LCAQ, especially on the margins of the Mississippi embayment where LCAQ is relatively shallow or crops out. The aquifer does not extend north of approximately the 35th parallel because of a facies change in the LCCU. The aquifer is relatively thin, ranging from 50 to 195 ft thick with a median thickness of 125 ft (Hart and others, 2008). Continuous surfaces representing groundwater withdrawal zones used for drinking water were created for MRVA (combined domestic and public supply), MCAQ-domestic, MCAQ-public supply, LCAQ-domestic, and LCAQ-public supply, where the surfaces represent the altitude (in feet above North American Vertical Datum of 1988) of the bottom and top of the screened interval. Surfaces were created by kriging well points using Empirical Bayesian Kriging in ArcMap version 10.4 (ESRI, 2016). Well construction information for public supply (P) and domestic (D) wells and aquifer surfaces from the Mississippi Embayment hydrogeologic framework (Hart and others, 2008) were used to populate as much information as available about well use, well depth, screened interval, and aquifer as to improve the modeled surfaces. To assess error on the modeled surfaces, well datasets were separated into training (90 percent) and testing (10 percent) datasets for kriging and root mean square error was calculated. The number of wells used for kriging varied for each surface (WellsSummary.csv). A shapefile representing the density of wells

Of the approximately 6.6 million people living in the Mississippi embayment (MISE) region in the central United States, approximately 65 percent rely on groundwater for their drinking water (Dieter, Linsey, and others, 2017). Regional assessments of water quality in principal aquifer systems provide context for the long-term availability of these water resources for drinking-water supplies. To assess the current (2018) status of water quality in MISE in relation to drinking water supplies, groundwater withdrawal zones used for domestic and public supply were modeled using available groundwater well and hydrogeologic framework data. Three dimensional surfaces were modeled to map the depth zones at which groundwater is withdrawn for drinking water. These surfaces will be used to model groundwater quality as part of the U.S. Geological Survey National Water Quality Assessment project’s intensive principal aquifer analysis. The MISE region includes two principal aquifer systems: the surficial aquifer system, which is dominated by the Quaternary Mississippi River Valley Alluvial aquifer (MRVA), and the Mississippi embayment aquifer system, which includes deeper Tertiary aquifers and confining units. Based on the distribution of groundwater use for drinking water, the modeling effort is focused on MRVA and two hydrogeologic units from the deeper system, including the middle Claiborne aquifer (MCAQ) and lower Claiborne aquifer (LCAQ). The MRVA is a surficial, unconfined to semi-confined, highly productive aquifer used mostly for irrigation, with a lesser amount of groundwater use for public supply and domestic self-supply (Clark and others, 2011; Maupin and Barber, 2005). The median thickness of the MRVA is about 130 feet (ft) but it can be as much as 290 ft thick (Hart and others, 2008). The MCAQ is confined where overlain by the Middle Claiborne confining unit and is used dominantly for public supply. Domestic self-supply occurs along outcrop areas where the unit is shallower or crops out. The unit consists mostly of the Sparta Sand, but north of approximately the 35th parallel (near the border between Tennessee and Mississippi), the underlying lower Claiborne confining unit (LCCU) undergoes a facies change and the Memphis Sand is included in the MCAQ (Hosman and Weiss, 1991). The MCAQ has a median thickness of about 805 ft, but it can be as much as 1,890 ft thick (Hart and others, 2008). Although not as regionally important as MRVA or MCAQ, domestic and public supply wells withdraw groundwater from LCAQ, especially on the margins of the Mississippi embayment where LCAQ is relatively shallow or crops out. The aquifer does not extend north of approximately the 35th parallel because of a facies change in the LCCU. The aquifer is relatively thin, ranging from 50 to 195 ft thick with a median thickness of 125 ft (Hart and others, 2008). Continuous surfaces representing groundwater withdrawal zones used for drinking water were created for MRVA (combined domestic and public supply), MCAQ-domestic, MCAQ-public supply, LCAQ-domestic, and LCAQ-public supply, where the surfaces represent the altitude (in feet above North American Vertical Datum of 1988) of the bottom and top of the screened interval. Surfaces were created by kriging well points using Empirical Bayesian Kriging in ArcMap version 10.4 (ESRI, 2016). Well construction information for public supply (P) and domestic (D) wells and aquifer surfaces from the Mississippi Embayment hydrogeologic framework (Hart and others, 2008) were used to populate as much information as available about well use, well depth, screened interval, and aquifer as to improve the modeled surfaces. To assess error on the modeled surfaces, well datasets were separated into training (90 percent) and testing (10 percent) datasets for kriging and root mean square error was calculated. The number of wells used for kriging varied for each surface (WellsSummary.csv). A shapefile representing the density of wells