V.L. McGuire S.M. Peterson 2008 (Version 1.0, March 04, 2008) vector digital data U.S. Geological Survey Scientific Investigations Map 3042 Reston, Va U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?sim3042_gu V.L. McGuire S.M. Peterson 2008 PDF document U.S. Geological Survey Scientific Investigations Map 3042 Reston, Va U.S. Geological Survey http://pubs.usgs.gov/sim/3042/ The U.S. Geological Survey (USGS), in cooperation with the Lewis and Clark Natural Resources District (NRD), Lower Elkhorn NRD, Lower Loup NRD, Lower Platte North NRD, Lower Niobrara NRD, Middle Niobrara NRD, Upper Elkhorn NRD, and Upper Loup NRD, have agreed to cooperatively study water resources from prior to the beginning of irrigation development to 2005 in the Elkhorn-Loup Model (ELM) area using a ground-water-flow model. The ELM area covers approximately 30,800 square miles, and extends from the Niobrara River in the north to the Platte River in the south. The western boundary of the ELM area coincides with the western boundary of the Middle Niobrara, Twin Platte, and Upper Loup NRDs; the eastern boundary coincides with the approximate location of the westernmost extent of glacial till in eastern Nebraska. The initial ground-water-flow model was constructed with a single layer vertically to represent the aquifers of the Tertiary-age Ogallala Group and Quaternary-age alluvial deposits, with a uniform node spacing of 2 miles. The model will be calibrated to measured ground-water levels and estimated ground-water discharge to streams for the pre-ground-water development period (approximately 1940) and the simulation of the 1940-2005 period will be calibrated to measure ground-water level changes. The study results will assist Nebraska Department of Natural Resources and the NRDs in the ELM area to develop long-term strategies for managing hydrologically connected waters. This dataset is one of three geospatial datasets that together revise previously published maps of the configuration of the base of the principal aquifer and of the geologic units that form the base of the principal aquifer in the study area; the revisions to the base-of-aquifer altitude are based on currently available or reinterpreted geologic logs of test holes and selected registered wells. The principal aquifer is the High Plains aquifer except in the northeast part of the model area, where the principal aquifer is an unnamed alluvial aquifer. This dataset identifies and delimits approximately the extent of the geologic units forming the base of the principal aquifer and the areas where the base of principal aquifer surface is not well defined. Ambiguity in the calculated base of aquifer existed wherever this calculated base-of-aquifer altitude was above the mapped land surface. The calculated base of aquifer was above the mapped land surface either because of inaccuracy in the mapped land surface or base of aquifer calculation or because the principal aquifer was thin or not present. The purpose of this data release is to make available geospatial data that identity and delimit approximately the extent of the geologic units forming the base of the principal aquifer and the areas where the principal aquifer is not well defined in the Elkhorn-Loup Model area, north-central Nebraska. The dataset was produced in support of the Elkhorn-Loup Model. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this Federal Geographic Data Committee-compliant metadata file is intended to document the dataset in nonproprietary form, as well as in ArcGIS format, this metadata file may include some ArcGIS-specific terminology. 2008 publication date Complete As needed -102.128248 -97.274685 42.925235 40.598895 None USGS High Plains aquifer Elkhorn-Loup Model Area aquifer base Ogallala aquifer ISO 19115 Topic Category inlandWaters geoscientificInformation Water Resources Thesaurus Aquifer characteristics Geohydrologic units None Nebraska None Brule Formation White River Group Upper Cretaceous Lower Tertiary Chadron Formation Pierre Shale Niobrara Formation none This dataset is not intended to be used at scales larger than 1:350,000. McGuire, V.L. U.S. Geological Survey Hydrologist mailing address

5231 South 19th Street

Lincoln NE 68512 USA (402)328-4100 (402)328-4101 Webmaster@ne20dnelnc.cr.usgs.gov http://water.usgs.gov/GIS/browse/sim3042_gu.gif Illustration of dataset. GIF This dataset was prepared in cooperation with the Lewis and Clark Natural Resources District (NRD), Lower Elkhorn NRD, Lower Loup NRD, Lower Platte North NRD, Lower Niobrara NRD, Middle Niobrara NRD, Upper Elkhorn NRD, and Upper Loup NRD. The dataset was prepared using published datasets and reports by the Cooperative Hydrology Study, Nebraska Oil and Gas Commission, University of Nebraska-Lincoln, Conservation and Survey Division, and the U.S. Geological Survey and unpublished data in the test-hole files assembled by J.F. Ayers and maintained by the University of Nebraska-Lincoln, Conservation and Survey Division. E.D. Gutentag, U.S. Geological Survey (retired); J.B. Swinehart, University of Nebraska-Lincoln, Conservation and Survey Division; J.C. Cannia, U.S. Geological Survey; R.F. Diffendal, Jr., University of Nebraska-Lincoln, Conservation and Survey Division; and S.O. Lackey, University of Nebraska-Lincoln, Conservation and Survey Division, reviewed the report and provided valuable feedback. In addition, J.W. Goeke, University of Nebraska-Lincoln, Conservation and Survey Division, provided assistance interpreting the unpublished test-hole information and R.M. Joeckel, University of Nebraska-Lincoln, Conservation and Survey Division, provided assistance with the test-hole data. Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcCatalog 9.3.0.1770 McGuire, V.L. Peterson, S.M. 2009 vector digital data U.S. Geological Survey Scientific Investigations Map 3042 Reston, Va U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?sim3042_tw McGuire, V.L. S.M. Peterson 2008 pdf document U.S. Geological Survey Scientific Investigations Map 3042 Reston, Va U.S. Geological Survey http://pubs.usgs.gov/sim/3042/ McGuire, V.L. Peterson, S.M. 2009 vector digital data U.S. Geological Survey Scientific Investigations Map 3042 Reston, Va U.S. Geological Survey http://water.usgs.gov/lookup/getspatial?sim3042_ab McGuire, V.L. Peterson, S.M. 2008 pdf document U.S. Geological Survey Scientific Investigations Map 3042 Reston, Va U.S. Geological Survey http://pubs.usgs.gov/sim/3042 The mapped geologic units were compared to published reports, if available (see references listed in source information). The designations of the geologic unit that forms the base of the aquifer were reviewed by geologists familiar with the area--E.D. Gutentag, U.S. Geological Survey (retired); J.B. Swinehart, University of Nebraska-Lincoln, Conservation and Survey Division; J.C. Cannia, U.S. Geological Survey; R.F. Diffendal, Jr., University of Nebraska-Lincoln, Conservation and Survey Division; and S.O. Lackey, University of Nebraska-Lincoln, Conservation and Survey Division. Their feedback was incorporated into the report and the map. The density of registered wells and test holes with data about the geologic unit that forms the base of aquifer varies greatly across the map area. The accuracy of the extent of geologic units that form the aquifer base in a given area is related directly to the density and availability of registered well and test-hole data with relevant information in that area. The approximate horizontal accuracy was derived by estimating the average distances between the registered wells and test holes in the vicinity of the geologic unit boundaries; this estimate is 3 miles. Polygon topology is present. The Arc Workstation Labelerrors command were used to verify that each polygon had one and only one label point. The contacts of the geologic units that underlie the principal aquifer, and the areas where the base of the principal aquifer is not well defined, were based on the stratigraphic information from the test-hole lithologic and borehole geophysical logs as interpreted by the University of Nebraska-Lincoln, Conservation and Survey Division geologists and by the authors. These contacts are approximate, especially in areas where there are few test holes supporting the identity of the mapped geologic unit. Varies, typically within about 3 miles, but it depends on the density of applicable wells and test holes. Not applicable Bentall, Ray Dreeszen, V.H Elder, J.A. Jess, J.M. Souders, V.L. Birkel, W.H. Braun, K.J. Ellis, M.J. Engel, G.B. Engberg, R.A. Shaffer, F.B. 1971 document Resource Atlas No. 1 Lincoln, Ne University of Nebraska-Lincoln, Conservation and Survey Division 1000000 paper unknown publication date Bentall and others, 1971 Geologic units in lower Elkhorn River Basin, Nebraska Burchett, R.R. Reed, E.C. Dreeszen, V.H. Prichard, G.E. 1975 raster digital data U.S. Geological Survey Miscellaneous Investigations Series Map I-905 Reston, Va U.S. Geological Survey http://ngmdb.usgs.gov/Prodesc/proddesc_9487.htm 250000 online and paper unknown publication date Map I-905 Extent of bedrock units in the Fremont 1-degree by 2-degree quadrangle. Burchett, R.R. Dreeszen, V.H. Souders, V.L. Prichard, G.E. 1988 raster digital data U.S. Geological Survey Miscellaneous Investigations Series, Map I-1879 Reston, Va U.S. Geological Survey http://ngmdb.usgs.gov/Prodesc/proddesc_9965.htm 250000 online and paper unknown publication date Map I-1879 Extent and altitude of bedrock units in the Nebraska part of the Sioux City 1-degree by 2-degree quadrangle. COHYST 2006 tabular digital data Well and test-hole database used by COHYST Issue identification, not specified Lincoln, Ne Nebr. Dept. of Natural Resources Cooperative Hydrology Study data accessed on November 2006 http://cohyst.dnr.ne.gov/cohyst_preliminarydata.html 250000 online unknown publication date Testholes and wells, COHYST (2006) Wells and testholes used to map the altitude of bedrock and configuration of the base of aquifer in the Cooperative Hydrology Study (COHYST) area. Diffendal, Jr., R.F 1991 raster digital data U.S. Geological Survey Miscellaneous Investigations Series Map I-2277 Reston, Va U.S. Geological Survey http://ngmdb.usgs.gov/Prodesc/proddesc_10209.htm 250000 online and paper unknown publication date Map I-2277 Extent and altitude of bedrock units in the North Platte 1-degree by 2-degree quadrangle. Dreeszen, V.H. Reed, E.C. Burchett, R.R. Prichard, G.E. 1973 raster digital data U.S. Geological Survey Miscellaneous Investigations Series Map I-819 Reston, Va U.S. Geological Survey http://ngmdb.usgs.gov/Prodesc/proddesc_9648.htm 250000 online and paper unknown publication date Map I-819 Extent of bedrock units in the Grand Island 1-degree by 2-degree quadrangle. Eversoll, D.A. Dreeszen, V.H. Burchett, R.R. Prichard, G.E. 1988 raster digital data U.S. Geological Survey Miscellaneous Investigations Series Map I-1878 Reston, Va U.S. Geological Survey http://ngmdb.usgs.gov/Prodesc/proddesc_9964.htm 250000 online and paper unknown publication date Map I-1878 Extent of bedrock units in the McCook 1-degree by 2-degree quadrangle. Nebraska Department of Natural Resources 2007 vector digital data Lincoln, Ne Nebraska Department of Natural Resources Nebraska Department of Natural Resources data accessed in July 2007 http://dnrdata.dnr.ne.gov/wellssql/ online unknown publication date Registered wells database, Nebraska If a registered well was drilled to or below the base of the aquifer and the geologic log is sufficiently descriptive, the source provided the depth to the base of aquifer at the well location. Nebraska Oil and Gas Commission 2007 tabular digital data Current database of oil and gas wells Issue identification, not specified Sidney, Ne Nebraska Oil and Gas Commission Nebraska Oil and Gas Commission data accessed May 2007 http://nogcc.ne.gov/ online unknown publication date Nebraska Oil and Gas Commission data Altitude of bedrock units at well locations. Pettijohn, R.A. Chen, H.H. 1983 document U.S. Geological Survey Open-File Report 82-502 Reston, Va U.S. Geological Survey http://pubs.er.usgs.gov/usgspubs/ofr/ofr82502 750000 paper unknown publication date OFR 82-502 This source includes a map of the base of the High Plains aquifer in Nebraska and of the geologic units that form the base of the aquifer. This source was visually compared to the current map of the base of aquifer and the extent of the geologic units that form the base of aquifer; the current maps were derived from this source and data acquired since this source was published. Souders, V.L. 2000 vector digital data U.S. Geological Survey Miscellaneous Investigations Series Map I-2725 Reston, Va U.S. Geological Survey http://ngmdb.usgs.gov/Prodesc/proddesc_28120.htm 250000 online and paper unknown publication date Map I-2725 Extent and altitude of bedrock units in the Broken Bow 1-degree by 2-degree quadrangle. Swinehart, J.B. Souders, V.L. DeGraw, H.M. Diffendal, Jr., R.F. 1985 document Flores, R.M. Kaplan, S.S., eds. 1985 document Denver, Co Rocky Mountain Section, Society of Economic Paleontologist and Mineralogists 1250000 paper unknown publication date Cenozoic paleogeography of western Nebraska This source contains a configuration map of the base of the Ogallala Group and of the presence of the Ogallala Group in western Nebraska. This source was used to estimate drainage patterns in the current base-of-aquifer map and to identify areas where the Ogallala Group was not present. Swinehart, J.B. Diffendal, Jr., R.F. 1998 document Resource Atlas No. 5b, p. 29-42 Bleed, A.S. Flowerday, C.A., eds. 1998 document Resource Atlas No. 5b Lincoln, Ne University of Nebraska-Lincoln, Conservation and Survey Division 1000000 paper unknown publication date Geology of the pre-dune strata This source contains a configuration map of the base of the Ogallala Group and of the presence of the Ogallala Group in the Sand Hills area in Nebraska. This source was used to estimate drainage patterns in the current base-of-aquifer contour map and to identify areas where the Ogallala Group was not present. University of Nebraska-Lincoln, Conservation and Survey Division 2007 tabular digital data Lincoln, Ne University of Nebraska-Lincoln, Conservation and Survey Division University of Nebraska-Lincoln, Conservation and Survey Division data accessed June 2007. http://csd.unl.edu/general/testholes.asp online unknown publication date Nebraska test-hole database Altitude of bedrock units at test-hole locations. U.S. Geological Survey and Nebraska Department of Natural Resources 1998 Series name, not specified Issue identification, not specified Lincoln, Ne U.S. Geological Survey and Nebraska Department of Natural Resources Data accessed June 2006 http://dnr.ne.gov/databank/dem.html 24000 online unknown publication date DEM 10-m This source was used to estimate the land surface altitude at each well and test-hole location. The published and unpublished stratigraphic data were assembled from test-holes and wells records maintained by the Cooperative Hydrology Study (COHYST); Nebraska Department of Natural Resources; Nebraska Oil and Gas Commission; and the University of Nebraska-Lincoln, Conservation and Survey Division. COHYST base of aquifer data Nebraska Oil and Gas Commission data Nebraska test-hole database Registered wells database, Nebraska 2007 The geologic units that form the base of aquifer were plotted for each of the test-hole and registered wells and polygons were drawn on-screen for the areas with the same geologic unit forming the base of aquifer. The source data for test-holes and selected registered wells were re-examined when the designation for the geologic unit that forms the base of aquifer was anomalous. When needed, corrected values for the identity of the geologic unit that forms the base of aquifer were assigned, if known. The land-surface altitude, as estimated by the 10-m DEM, was compared to the base-of-aquifer surface. Areas where the represented base-of-aquifer surface was above the estimated land surface was interpreted to be areas where either the base of aquifer surface was inaccurate or areas where the principal aquifer is thin or not present. 2007 The base-of-aquifer contours and the designation of the geologic unit that form the base of the aquifer were reviewed by geologists familiar with the area--E.D. Gutentag, U.S. Geological Survey (retired); J.B. Swinehart, University of Nebraska-Lincoln, Conservation and Survey Division; J.C. Cannia, U.S. Geological Survey; R.F. Diffendal, Jr., University of Nebraska-Lincoln, Conservation and Survey Division; and S.O. Lackey, University of Nebraska-Lincoln, Conservation and Survey Division. Their suggestions were incorporated into the dataset and the map. 2007 Metadata imported. P:\C8T02\GIS\aqbase\20090604_4approval_sim3042_gu.xml 20090604 12480400 Vector Complete chain 166 Label point 40 GT-polygon composed of chains 41 State Plane Coordinate System 1983 2600 40.000000 43.000000 -100.000000 39.833333 1640416.666667 0.000000 coordinate pair 15280 15280 Feet North American Datum of 1983 Geodetic Reference System 80 6378137.000000 298.257222 sim3042_gu.pat Feature attribute table for mapped polygons representing the geologic units that form the base of aquifer and areas where the base of aquifer is well defined. See references listed in source information. FID Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. Shape Feature geometry. ESRI Coordinates defining the features. AREA Area of feature in internal units squared. ESRI Positive real numbers that are automatically generated. PERIMETER Perimeter of feature in internal units. ESRI Positive real numbers that are automatically generated. SIM3042_GU# Internal feature number. ESRI Sequential unique whole numbers that are automatically generated. SIM3042_GU-ID User-defined feature number. ESRI Sequential unique whole numbers that were automatically generated. GEO_UNIT Identity of geologic units that form the base of the aquifer, or alternatively, a code signifying an area where the base of the principal aquifer is not well defined. Within the study area, the geologic units of the Lower Tertiary system generally are the Brule and Chadron Formation of the White River Group, but, for some test holes, the aquifer base was noted more generally as the White River Group. The geologic units of the Upper Cretaceous system are the Pierre Shale, Niobrara Formation, or Carlile Shale. See references listed in source information. LT A geologic unit of Lower-Tertiary age forms the base of aquifer in this area. These geologic units, in this area, generally are the Brule and Chadron Formation of the White River Group. See references listed in source information. UK A geologic unit of Upper-Cretaceous age forms the base of aquifer in this area. These geologic units, in this area, generally are the Pierre Shale, Niobrara Formation of the Colorado Group, or the Carlie Shale of the Colorado Group. See references listed in source information. NA The base of the principal aquifer is not well defined in this area. See references listed in source information. The relevant attributes for this dataset are: geo-unit, for the geologic units that form the base of aquifer and the areas where the aquifer is not well-defined. See references listed in source information. U.S. Geological Survey Ask USGS - Water Webserver Team mailing address

507 National Center

Reston Va 20192 USA 1-888-275-8747 (1-888-ASK-USGS) http://water.usgs.gov/user_feedback_form.html Contact via email Downloadable Data 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. ARCE Spatial and attribute information Winzip 0.5 Mbytes http://water.usgs.gov/GIS/dsdl/sim3042gu_e00.zip Shape Shape file zipped 1.0 Mbytes http://water.usgs.gov/GIS/dsdl/sim3042gu_shp.zip None. This dataset is provided by USGS as a public service. 20090603 U.S. Geological Survey Ask USGS - Water Webserver Team mailing

455 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+sim3042gu FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998 None Unclassified Not applicable