Melissa D. Masbruch Susan G. Buto 2011 vector digital data Reston, VA U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?sir2010_5193_potentiometric1000 Heilweil, V.M., editor Brooks, L.E., editor 2011 document U.S. Geological Survey Scientific Investigations Report SIR2010-5193 Reston, VA U.S. Geological Survey http://pubs.usgs.gov/sir/2010/5193 This dataset was created in support of a U.S. Geological Survey (USGS) study focusing on groundwater resources in the Great Basin carbonate and alluvial aquifer system (GBCAAS). The GBCAAS is a complex aquifer system comprised of both unconsolidated and bedrock formations covering an area of approximately 110,000 square miles. The aquifer system is situated in the eastern portion of the Great Basin Province of the western United States. The eastern Great Basin is experiencing rapid population growth and has some of the highest per capita water use in the Nation. These factors, combined with the arid setting, have levied intensive demand upon current groundwater resources and, thus, predictions of future shortages. Because of the large regional extent of the aquifer system, rapid growth in the region, and the reliance upon groundwater for urban populations, agriculture, and native habitats, the GBCAAS was selected by the USGS Water Resources program as part of the National Water Census Initiative to evaluate the Nation's groundwater availability. This dataset consists of potentiometric contours, control points used to guide the creation of the contours, and a grid of 2 square-mile cells used to average the water-level value of selected control points. Control points are based on water-level measurements at well and spring locations from the USGS National Water Information System (NWIS, Mathey, 1998). Additional control points were derived from estimates of water-level altitudes in perennial mountain streams based on National Hydrography Dataset (NHD, 1999) stream reaches. References cited: Mathey, Sharon B., ed., 1998, National Water Information System (NWIS): U.S. Geological Survey Fact Sheet 027-98, 2 p., Accessed January 14, 2009 at <http://pubs.usgs.gov/fs/FS-027-98/fs-027-98.pdf> U.S. Geological Survey, 1999, National Hydrography Dataset: U.S. Geological Survey Fact Sheet 106-99, accessed March 2007 at http://erg.usgs.gov/isb/pubs/factsheets/fs10699.html This dataset was created to support hydrologic investigations in the Great Basin Physiographic Province. The intended uses of this dataset include, but are not limited to, natural resource modeling, mapping, and visualization applications. 2011 publication date Complete None planned -118.647404 -111.009994 42.511846 35.171686 ISO 19115 topic category inlandWaters none Potentiometric contour Water-level altitude Groundwater-level altitude none Great Basin Utah Nevada Idaho California None. This data set is provided by USGS as a public service. Although this Federal Geographic Data Committee (FGDC) compliant metadata file is intended to document the dataset in nonproprietary form, this metadata file may include some ArcGIS-specific terminology. These data are not intended to be used as a survey product and are for reference only. U.S. Geological Survey Utah Water Science Center Center Director mailing and physical address

2329 Orton Circle

Salt Lake City UT 84119 USA (801)908-5000 (801)908-5001 sbuto@usgs.gov http://water.usgs.gov/GIS/browse/sir2010_5193_potentiometric1000.jpg Illlustration of data set jpg Acknowledgement of the U.S. Geological Survey would be appreciated in products derived from these data. Technical review of this database was done by Shana L. Mashburn, USGS Oklahoma Water Science Center and Toby L. Welborn, USGS Nevada Water Science Center. Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 3; ESRI ArcCatalog 9.2.4.1420 Buto, S.G. Sweetkind, D.S. 2011 vector digital data Reston, VA U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?sir2010_5193_ha1000 Heilweil, V.M., editor Brooks, L.E., editor 2011 document U.S. Geological Survey Scientific Investigations Report SIR2010-5193 Reston, VA U.S. Geological Survey http://pubs.usgs.gov/sir/2010/5193 Brooks, L.E. Masbruch, M.M. Buto, S.G. 2011 vector digital data Reston, VA U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?sir2010_5193_GWdisch1000 Heilweil, V.M., editor Brooks, L.E., editor 2011 document U.S. Geological Survey Scientific Investigations Report SIR2010-5193 Reston, VA U.S. Geological Survey http://pubs.usgs.gov/sir/2010/5193 Sweetkind, D.S. Cederberg, J.R. Buto, S.G. Masbruch, M.M. 2011 raster digital data Reston, VA U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?sir2010_5193_3D_HGF Heilweil, V.M., editor Brooks, L.E., editor 2011 document U.S. Geological Survey Scientific Investigations Report SIR2010-5193 Reston, VA U.S. Geological Survey http://pubs.usgs.gov/sir/2010/5193 Alan L. Flint Lorraine E. Flint 2011 raster digital data Reston, VA U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?sir2010_5193_BCM Heilweil, V.M., editor Brooks, L.E., editor 2011 document U.S. Geological Survey Scientific Investigations Report SIR2010-5193 Reston, VA U.S. Geological Survey http://pubs.usgs.gov/sir/2010/5193 All attempts were made to verify 100 percent of the digital attribute data is complete and consistent. Verification was done by interactive on-screen review. Frequency tests were performed on all feature class attributes to check that no features were unlabeled, misspelled, or inconsistent. Corrections were made until two visual and manual comparisons, combined with on-screen review, determined 100 percent of the digital attribute data is complete and consistent. The logical consistency topologically is clean. Chain-node topology is present. Using ArcGIS tools and routines all lines were checked for node errors, overshoots, undershoots, dangles, intersections, and duplicate features. Complete for the eastern Great Basin. National map accuracy standards (NMAS) established for the United States in 1947 (U.S. Geological Survey, 1988) state that no more than 10 percent of features shall be more than 1/50th of an inch from their intended location on maps of scale smaller than 1:20,000. National standards for spatial data accuracy (NSSDA) published by the Federal Geographic Data Committee (FGDC) in 1998 relate the NMAS to the digital geospatial data standard by multiplying the NMAS accuracy by a factor of 1.1406 (Federal Geographic Data Committee, 1998) resulting in expected error in the geospatial data at standard mapping scales as follows: 1: 24,000-scale map - 14 meters 1: 62,500-scale map - 36 meters 1: 100,000-scale map - 58 meters 1: 250,000-scale map - 145 meters 1: 500,000-scale map - 290 meters 1:1,000,000-scale map - 579 meters All attempts were made to verify 100 percent of the digital spatial data with supporting source datasets. Two visual checks were done to verify that the digital data was a fair representation of hydrologic conditions in the study area. References Cited U.S. Geological Survey, 1988, National mapping program technical instructions --- Part 2: Specifications, Standards for Digital Line Graphs: U.S. Geological Survey, 56 p. Federal Geographic Data Committee, Subcommittee for Base Cartographic data, 1998, Geospatial Positioning Accuracy Standards, Part 3: National Standard for Spatial Data Accuracy, FGDC-STD-007.3-1998, last accessed 03/29/2007 at URL http://www.fgdc.gov/standards/projects/FGDC-standards-projects/accuracy/part3/chapter3 600 meters Errors resulting from source map quality, automation processes, and scale resolution can impact the accuracy of data. Errors resulting from the quality of the source map and automation processes are unknown. Taking all known and unknown sources of error into account the horizontal positional accuracy is deductively estimated at 600 meters. Water level altitude values used to control the creation of the potentiometric contours are from sources of widely varying vertical accuracy. In addition, the control points were created by merging measured and interpolated water levels from multiple locations to an average location at the center of a square sample grid. 75 meters Errors resulting from source map quality, automation processes, and scale resolution can impact the accuracy of data. Taking all known and unknown sources of error into account the vertical accuracy is deductively estimated at 75 meters. U.S. Geological Survey 2008 database http://waterdata.usgs.gov/nwis online 112008 ground condition NWIS spatial and attribute information U.S. Geological Survey Unknown vector digital data http://nhd.usgs.gov/ 100000 vector digital data 2010 publication date NHD spatial information U.S. Geological Survey Unknown raster digital data http://seamless.usgs.gov/ raster digital data 2010 publication date NED attribute information Buto, S.G. Sweetkind, D.S. 2011 vector digital data http://water.usgs.gov/lookup/getspatial?sir2010_5193_ha1000 1000000 vector digital data 2009 ground condition gbcaas ha spatial and attribute information Well locations and water-level altitude measurements were extracted from the USGS NWIS database. Water-level altitudes for each well were averaged over the period of record with no distinctions made between wells screened within basin fill and wells screened within bedrock. For areas with high well density, wells were merged to a single point at the center of a 2-mile square grid cell, and the time averaged water-level altitudes for each of these wells were averaged to a single water-level altitude at the centroid of the cell. Only nonpumping (static) water levels from wells were used to compute an average water-level altitude. NWIS 112008 control point wells Spring locations were acquired from the USGS NWIS database. Water-level altitudes were assumed to be equal to the spring elevation. Only single springs or groups of smaller springs, typically within 1 mile of each other, with discharge greater than 300 gallons per minute, were included as control points; springs with discharge less than 300 gallons per minute were assumed to represent localized, perched aquifers. NWIS 112008 control point springs Stream altitudes of perennial gaining streams located within the mountain block having a baseflow of at least 300 gallons per minute (with a few smaller exceptions) were used as control points. A median altitude was calculated for each perennial mountain stream reach and used as a control point in the potentiometric-surface map. In areas with multiple stream reaches, these median perennial stream altitudes were averaged over a 1 square-mile grid cell and the median altitude is represented as a point at the center of the cell for the potentiometric-surface map. NWIS NHD NED 112008 control point streams Well, spring, and stream locations were merged to a single dataset and intersected with the GBCAAS hydrographic area dataset. control point wells control point springs control point streams gbcaas ha 112008 sir20105193_potentiometric1000_x The control point dataset was used as a guide to digitizing potentiometric contours for the study area. Contours were digitized on-screen using ArcGIS 9.2 software. The draft potentiometric contours were compared to land-surface altitudes using the U.S. Geological Survey's National Elevation Dataset. If a potentiometric contour altitude was greater than 100 ft above the NED altitude in areas without water-level control points, the location of the contour was adjusted until it was less than 100 ft above the NED altitude. sir20105193_potentiometric1000_x 112008-122008 sir20105193_potentiometric1000_l Vector G-polygon 265 String 793 Albers Conical Equal Area 29.500000 45.500000 -114.000000 23.000000 0.000000 0.000000 coordinate pair 0.000167 0.000167 meters North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222 North American Vertical Datum of 1988 0.000100 meters Explicit elevation coordinate included with horizontal coordinates sir20105193_potentiometric1000_l Line feature class representing potentiometric contours User defined OBJECTID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. SHAPE Feature geometry. ESRI Coordinates defining the features. altitude_ft Water-level altitude in feet User defined -200 9300 Feet altitude_m Water-level altitude in meters User defined -60.957025 2834.501676 Meters SHAPE_Length Length of feature in internal units. ESRI Positive real numbers that are automatically generated. sir20105193_potentiometric1000_x Point feature class containing control points used to create potentiometric contours User defined OBJECTID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. SHAPE Feature geometry. ESRI Coordinates defining the features. source The source of the point User defined gaged stream median The point location was calculated as the median elevation of a perennial stream reach User defined spring The point location is a spring or group of springs User defined well The point location is a well or a group of wells User defined average_wl_alt_ft Average water level altitude at the point User defined -276 9645 Feet hyd_area The hydrographic area in which the point falls User defined Hydrographic area number - see cross reference citations for details mesh_code code identifying how point values were averaged User defined 0 Water-level values from a single source were averaged for the period of record of the source User defined 1 Water-level altitude derived from the median altitude of perennial gaining streams located within the mountain block and having a baseflow of at least 300 gallons per minute User defined 2 Water-level values from all wells falling within the boundary of each 2 square-mile grid cell were averaged for the period of record of each well. The average water level for all wells within a grid cell was then used to calculate the average water level within the grid cell. The water level was assigned to a point at the center of the grid cell. User defined sir20105193_potentiometric_2milegrid_p Polygon feature class of 2 square-mile grid cells used to spatially average dense control points User defined OBJECTID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Shape Feature geometry. ESRI Coordinates defining the features. Shape_Length Length of feature in internal units. ESRI Positive real numbers that are automatically generated. Shape_Area Area of feature in internal units squared. ESRI Positive real numbers that are automatically generated. sir20105193_potentiometric_1milegrid_p Polygon feature class of one square-mile grid cells used to locate median gaining stream elevations. User defined OBJECTID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Shape Feature geometry. ESRI Coordinates defining the features. Shape_Length Length of feature in internal units. ESRI Positive real numbers that are automatically generated. Shape_Area Area of feature in internal units squared. ESRI Positive real numbers that are automatically generated. U.S. Geological Survey Ask USGS -- Water Webserver Team mailing address

445 National Center

Reston VA 20192 1-888-275-8747 (1-888-ASK-USGS) http://answers.usgs.gov/cgi-bin/gsanswers?pemail=h2oteam&subject=GIS+Dataset+SIR2010_5193_potentiometric1000 Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the U.S. Geological Survey in the use of these data, software, or related materials. The use of firm, trade, or brand names in this report is for identification purposes only and does not constitute endorsement by the U.S. Geological Survey. The names mentioned in this document may be trademarks or registered trademarks of their respective trademark owners. WinZipped personal geodatabase 9.2 ESRI 9.2 personal geodatabase Spatial and attribute information http://water.usgs.gov/GIS/dsdl/SIR2010_5193_potentiometric1000.pgdb.zip WinZipped shapefile 07252011 ESRI shapefile. Note some information such as field names and relationship classes may be altered or removed from the source data during conversion to ESRI shapefile format Spatial and attribute information http://water.usgs.gov/GIS/dsdl/SIR2010_5193_potentiometric1000.shape.zip None. This data set is provided by USGS as a public service. 20081104 U.S. Geological Survey Ask USGS -- Water Webserver Team mailing address

445 National Center

Reston VA 20192 1-888-275-8747 (1-888-ASK-USGS) http://water.usgs.gov/user_feedback_form.html FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998