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 its 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 contains hydrographic area (HA) boundaries and polygons for the GBCAAS study area. The study area consists of 165 HAs based on Great Basin HAs defined by the USGS in 1988 (Harrill and others, 1988; Buto, 2009). The study area is characterized by north-south trending alluvial basins separated by intervening mountain ranges. HA boundaries generally coincide with the topographic highs separating these basins but may also contain arbitrary divisions that have no topographic control. HAs generally consist of thick layers of unconsolidated geologic deposits in the basins and consolidated bedrock in the mountain ranges. The basins are underlain by bedrock at varying depths. Much of the bedrock in the study area consists of permeable carbonate and volcanic rock strata, both of which allow some degree of hydraulic connection between hydrographic areas. The hydrographic area boundaries in this dataset have been assigned a code identifying each boundary as a potential barrier, conduit, or neutral zone to groundwater flow between basins. References cited: Buto, S.G., 2009, Digital representation of 1:1,000,000-scale Hydrographic Areas of the Great Basin: U.S. Geological Survey Digital Data Report 457, 5 p., Harrill, J.R., Gates, J.S., and Thomas, J.M., 1988, Major ground-water flow systems in the Great Basin region of Nevada, Utah, and adjacent states: U.S. Geological Survey Hydrologic Investigations Atlas HA-694-C, 2 sheets, scale 1:1,000,000.

This data set consists of 1:500,000-scale depth-to-water area polygons for the Humboldt River Basin, Nevada as published in the Nevada Department of Conservation and Natural Resources Water Resources Bulletin 32 titled "Hydrologic reconnaissance of the Humboldt River basin, Nevada", 1966.

This dataset consists of digitized 1:24,000-scale polylines and polygons representing hydrographic areas for the Walker River basin, California and Nevada.

This data set consists of 1:1,000,000-scale areas where shallow ground water is consumed by evapotranspiration (ET) in the Great Basin. The source of this data set is sheet 2 of a 1988 U.S. Geological Survey hydrologic investigations atlas map (Harrill and others, 1988.) Reference Cited Harrill, J.R., Gates, J.S., and Thomas, J.M., 1988, Major ground-water flow systems in the Great Basin region of Nevada, Utah, and adjacent states: U.S. Geological Survey Hydrologic Investigations Atlas HA-694-C, scale 1:1,000,000, 2 sheets.

This dataset contains the amalgamation of the hydrographic area (HA) boundaries and polygons for the GBCAAS study area. The study area consists of 165 HAs based on Great Basin HAs defined by the USGS in 1988 (Harrill and others, 1988; Buto, 2009). This dataset does not contain the HA boundaries or geologic details included in the source dataset. For that information, please see the metadata for the source dataset at https://water.usgs.gov/GIS/metadata/usgswrd/XML/sir2010_5193_ha1000.xml The study area boundary dataset is used by the Office of Groundwater, U.S. Geological Survey, in its hyrogeological framework website.

This data set contains the topographic and administrative hydrographic area boundaries for the Humboldt River Basin at 1:24,000-scale.

This data set consists of the administrative hydrographic area (HA) boundaries for Nevada at 1:750,000-scale and estimates of natural recharge, artificial recharge, pumpage, and net ground-water flow for each basin where the information is available. Formal hydrographic areas in Nevada were delineated systematically by the U.S. Geological Survey and Nevada Department of Conservation and Natural Resources, Division of Water Resources (NDWR) in the late 1960's (Rush, 1968; Cardinalli and others, 1968) for scientific and administrative purposes. The official hydrographic area names, numbers, and geographic boundaries continue to be used in U.S. Geological Survey scientific reports and NDWR administrative activities. Although the boundary lines between hydrographic areas generally coincide with true topographic basin divides, some of the lines are arbitrary divisions that have no topographic control. The pumpage, recharge, and interbasin flow estimates were derived from a variety of sources and methods. The data were tabulated and published by Lopes and Evetts in 2004. References Cited Cardinalli, J.L., Roach, L.M., Rush, F.E., and Vasey, B.J., comps., 1968, State of Nevada hydrographic areas: Nevada Department of Conservation and Natural Resources, Division of Water Resources map, scale 1:500,000. Lopes, T.J. and Evetts, D.M., 2004, Ground-water pumpage and artificial recharge for 2000 and average annual natural recharge and inter-basin flow by hydrographic area: U.S. Geological Survey Scientific Investigations Report 2004-5239, 81 p. Rush, F.E., 1968, Index to hydrographic areas in Nevada: Nevada Department of Conservation and Natural Resources, Division of Water Resources, Information Report 6, 38 p. Rush, F.E., 1974, Static ground water levels of Nevada: Nevada Department of Conservation and Natural Resources, Division of Water Resources map, 1 sheet, scale 1:750,000.

The Great Basin is characterized by strong patterns of precipitation along approximate north-south gradients (Miller and others, 2013). Hence, we used a hydrographic boundary layer developed by Mason (1999), to divide the region-wide extent of sage-grouse habitat mapping analysis into North and South regions that align coarsely with respective mesic (wet) and xeric (dry) regions of the state. Flood regions are based largely on patterns of snowmelt, summer thunderstorms or cyclonic rainfall, and the 8-digit Watershed Boundary Dataset (WBD, 2015) was used to select appropriate watersheds within our mapping extent that corresponded to the Mason (1999) boundary. Slight adjustments, made in ArcMap 10.3, included joining region 2 and 3 to comprise the majority of the North region (where a relatively low number of sampled sites precluded keeping regions 2 and 3 separate), and pooling the more xeric Owyhee Desert (located in the center of the northern part of Nevada) within the drier South region. Use of the hydrographic boundary allowed for an accounting of broad-scale variation in habitat availability and selection patterns for sage-grouse (for example, habitat classified as highly suitable in wet areas could be classified as less suitable in drier areas because these habitats are less available). Interim statewide habitat suitability maps were clipped by the hydrographic boundary and relativized according to their respective maximum values for map classification purposes (see Coates and others 2014), the independent set of sage-grouse telemetry points was also split by the hydrographic boundary. For the spring map, 837 points informed the North region while 794 informed the South region. For the summer map, 604 points informed the North and 794 the South. For winter, 326 informed the North and 411 the South. For our composite annual map made from the multiplicative product of the seasonal maps, 1767 points were used for the North and 1999 for the South. References: Coates, P.S., Casazza, M.L., Brussee, B.E., Ricca, M.A., Gustafson, K.B., Overton, C.T., Sanchez-Chopitea, E., Kroger, T., Mauch, K., Niell, L., Howe, K., Gardner, S., Espinosa, S., and Delehanty, D.J. 2014, Spatially explicit modeling of greater sage-grouse (Centrocercus urophasianus) habitat in Nevada and northeastern California—A decision-support tool for management: U.S. Geological Survey Open-File Report 2014-1163, 83 p., http://dx.doi.org/10.3133/ofr20141163. ISSN 2331-1258 (online) Mason, R.R. 1999. The National Flood-Frequency Program—Methods For Estimating Flood Magnitude And Frequency In Rural Areas In Nevada U.S. Geological Survey Fact Sheet 123-98 September, 1999, Prepared by Robert R. Mason, Jr. and Kernell G. Ries III, of the U.S. Geological Survey; and Jeffrey N. King and Wilbert O. Thomas, Jr., of Michael Baker, Jr., Inc. http://pubs.usgs.gov/fs/fs-123-98/ Miller RF, Chambers JC, Pyke DA, Pierson FB, Williams CJ. 2013. A review of fire effects on vegetation and soils in the Great Basin Region: response and ecological site characteristics. Gen. Tech. Rep. RMRS-GTR-308. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. http://www.fs.fed.us/rm/pubs/rmrs_gtr308.html. WBD, 2015. Coordinated effort between the United States Department of Agriculture-Natural Resources Conservation Service (USDA-NRCS), the United States Geological Survey (USGS), and the Environmental Protection Agency (EPA). The Watershed Boundary Dataset (WBD) was created from a variety of sources from each state and aggregated into a standard national layer for use in strategic planning and accountability. Watershed Boundary Dataset for {HUC#8}, Nevada_ST.zip [ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Hydro/FileGDB101/]. Available URL: http://datagateway.nrcs.usda.gov [Accessed 01/10/2015].

This data set represents the extent of the California Coastal Basin aquifers in California.

This data set consists of 1:500,000-scale water-level altitude contours for the Humboldt River Basin, Nevada as published in the Nevada Department of Conservation and Natural Resources Water Resources Bulletin 32 titled "Hydrologic reconnaissance of the Humboldt River basin, Nevada", 1966.