This map service contains the most current version of the USGS Watershed Boundary Dataset (WBD) from The National Map (TNM). The WBD defines the perimeter of drainage areas formed by the terrain and other landscape characteristics. These drainage areas or Hydrologic Unit (HU) polygon boundaries are available for the United States, Puerto Rico, and the U.S. Virgin Islands. The drainage areas are nested within each other so that a large drainage area, such as the Upper Mississippi River, will be composed of multiple smaller drainage areas, such as the Wisconsin River. Each of these smaller areas can further be subdivided into smaller and smaller drainage areas. The WBD uses six different levels in this hierarchy, with the smallest averaging about 30,000 acres. The WBD is made up of polygons nested into six levels of data respectively defined by Regions, Subregions, Basins, Subbasins, Watersheds, and Subwatersheds.The data is a seamless National representation of HU boundaries from 2 to 14 digits compiled from U.S. Geological Survey (USGS) National Hydrography Dataset (NHD) and U.S. Department of Agriculture (USDA) National Resources Conservation Service (NRCS) Watershed Boundary Dataset (WBD) sources. Purpose: This data is intended primarily for geographic display and analysis of regional and national data, and can also be used for illustration purposes at intermediate or small scales (1:250,000 to 1:2,000,000). For additional information on the WBD, go to https://nhd.usgs.gov/wbd.html.

The Watershed Boundary Dataset (WBD) from USGS' The National Map (TNM) defines the perimeter of drainage areas formed by the terrain and other landscape characteristics. The drainage areas are nested within each other so that a large drainage area, such as the Sacramento River, will be composed of multiple smaller drainage areas, such as the Feather River. Each of these smaller areas can further be subdivided into smaller and smaller drainage areas. The WBD uses six different levels in this hierarchy, with the smallest averaging about 30,000 acres. The WBD is made up of polygons nested into six levels of data respectively defined by Regions, Subregions, Basins, Subbasins, Watersheds, and Subwatersheds. For additional information on the WBD, go to https://www.usgs.gov/core-science-systems/ngp/national-hydrography/watershed-boundary-dataset. DWR was the steward for NHD and WBD in California. We worked with other organizations to edit and improve NHD and WBD, using the business rules for California. California's WBD improvements are sent to USGS for certification and incorporation to the national geodatabase. The certified WBD is included within the National Hydrography Dataset downloadable file geodatabase, and is also available in shapefile format and as web map services accessible from the USGS website. (https://www.usgs.gov/core-science-systems/ngp/national-hydrography/access-national-hydrography-products).

The final static version of the WBD was published in January 2025. No edits to this dataset are being accepted by USGS. Future mapping of drainage areas will be done by USGS as the 3D Hydrography Program (3DHP) is built out. DWR and its stewardship partners are actively producing LiDAR-derived hydrography data for inclusion in the California portion of 3DHP data and eventually its companion set of drainage areas. For now, the WBD is considered the authoritative source for watershed delineations in California.

The California Interagency Watershed Map of 1999 (Calwater 2.2, updated May 2004, "calw221") is the State of California's working definition of watershed boundaries. Previous Calwater versions (1.2 and 2.2) described California watersheds, beginning with the division of the State's 101 million acres into ten Hydrologic Regions (HR). Each HR is progressively subdivided into six smaller, nested levels: the Hydrologic Unit (HU, major rivers), Hydrologic Area (HA, major tributaries), Hydrologic Sub-Area (HSA), Super Planning Watershed (SPWS), and Planning Watershed (PWS). At the Planning Watershed (the most detailed level), where implemented, polygons range in size from approximately 3,000 to 10,000 acres. At all levels, a total of 7035 polygons represent the State's watersheds. The present version, Calwater 2.2.1, refines the watershed coding structure and documentation (database fields were added and some were renamed). There are significant watershed boundary, code, and name differences between Calwater versions 1.2 (1995), 2.0 (1998), and 2.2 (1999). The differences between versions 2.2 (1999) and 2.2.1 (2004) are attribute field names and some inserted lines that identify differences between State and federal watersheds. Calwater 2.2.1 most accurately delineates true watersheds in mountainous terrain. However, neither Calwater 2.2.1 nor any of its predecessors is a "pure" watershed map because administrative boundaries such as the State border were used to delineate watershed areas. Some of the boundaries, particularly in developed valley areas, also have legal and administrative purposes other than the representation of actual drainage divides. Examples include the so-called "Legal Delta" (California Water Code, Chapter 2, the Delta, Sec. 12220) and other district boundaries. Neither is Calwater a legal map document, as it does not represent State of California Regional Water Quality Control Board (RWQCB) jurisdictions, officiated by the State Water Resources Control Board (SWRCB) under California Water Code Section 13200. Calwater is a hybrid, a spatial cross-reference for use in local, State, and federal information communities. The California Resources Agency (CRA) Department of Forestry and Fire Protection (CDF) contracted with Tierra Data Systems for the original digital production in 1993, based on Hydrologic Basin Planning Maps published in hardcopy (SWRCB, 1986). The State of California Stephen P. Teale Data Center GIS Solutions Group (Teale) under the direction of the California Department of Water Resrouces (DWR) and CDF, finalized the current version in ESRI ArcInfo coverage format in 1999 with USDA Forest Service and RWQCB/SWRCB inputs. The CRA California Spatial Information Library (CaSIL) is the current distributor of the coverage in the Teale Albers Conical Equal-Area projection, North American Datum of 1983. The California Department of Fish and Game (DFG) authored Calwater attribution design and documentation culminating in May 2004 with this Federal Geographic Data Committee (FGDC-STD-001-1998) standard metadata.This dataset comprises a portion of the full California dataset to cover hydrological basins that intersect San Diego County, Imperial County, Riverside County and Orange County.

Abstract: This data set is a complete digital hydrologic unit boundary layer to the Subwatershed (12-digit) 6th level for California. This data set consists of geo-referenced digital data and associated attributes created in accordance with the "FGDC Proposal, Version 1.0 - Federal Standards For Delineation of Hydrologic Unit Boundaries 3/01/02"(http://www.ftw.nrcs.usda.gov/huc_data.html). Polygons are attributed with hydrologic unit codes for 4th level sub-basins, 5th level watersheds, 6th level subwatersheds, name, size, downstream hydrologic unit, type of watershed, non-contributing areas and flow modification. Arcs are attributed with the highest hydrologic unit code for each watershed, linesource and a metadata reference file.

Purpose: The Watershed and Subwatershed hydrologic unit boundaries provide a uniquely identified and uniform method of subdividing large drainage areas. The smaller sized 6th level sub-watersheds (up to 250,000 acres) are useful for numerous application programs supported by a variety of local, State, and Federal Agencies. This data set is intended to be used as a tool for water-resource management and planning activities, particularly for site-specific and localized studies requiring a level of detail provided by large-scale map information. The dataset will be appended to a larger seamless nationally consistent geospatial database as other states complete their portion of the watershed boundary dataset.

Use_Constraints: The distributor shall not be held liable for improper or incorrect use of this data, based on the description of appropriate/inappropriate uses described in this metadata document. It is strongly recommended that this data is directly acquired from the distributor and not indirectly through other sources which may have changed the data in some way. These data should not be used at scales greater than 1:24,000 for the purpose of identifying hydrographic watershed boundary feature locations in the U.S.A. The NRCS should be acknowledged as the data source in products derived from these data. The Watershed Boundary Dataset is public information and may be interpreted by all organizations, agencies, units of government, or others based on needs; however, they are responsible for the appropriate application of the data. Federal, State, or local regulatory bodies are not to reassign to the Natural Resources Conservation Service any authority for the decisions they make. The Natural Resources Conservation Service will not perform any evaluations of these maps or purposes related solely to State or local regulatory programs. Photographic or digital enlargement of these maps to scales greater than that at which they were originally delineated can result in misrepresentation of the data. If enlarged, the maps will not include the fine detail that would be appropriate for mapping at the small scale. Digital data files are periodically updated. Files are dated, and users are responsible for obtaining the latest version of the data from the source distributor.

© Natural Resources Conservation Service (NRCS) USDA

Six digit hydrologic units intersecting California. The Watershed Boundary Dataset (WBD) is a comprehensive aggregated collection of hydrologic unit data consistent with the national criteria for delineation and resolution. It defines the areal extent of surface water drainage to a point except in coastal or lake front areas where there could be multiple outlets as stated by the "Federal Standards and Procedures for the National Watershed Boundary Dataset (WBD)" “Standard” (https://pubs.usgs.gov/tm/11/a3/). Watershed boundaries are determined solely upon science-based hydrologic principles, not favoring any administrative boundaries or special projects, nor particular program or agency. This dataset represents the hydrologic unit boundaries to the 12-digit (6th level) for the entire United States. Some areas may also include additional subdivisions representing the 14- and 16-digit hydrologic unit (HU). At a minimum, the HUs are delineated at 1:24,000-scale in the conterminous United States, 1:25,000-scale in Hawaii, Pacific basin and the Caribbean, and 1:63,360-scale in Alaska, meeting the National Map Accuracy Standards (NMAS). Higher resolution boundaries are being developed where partners and data exist and will be incorporated back into the WBD. WBD data are delivered as a dataset of polygons and corresponding lines that define the boundary of the polygon. WBD polygon attributes include hydrologic unit codes (HUC), size (in the form of acres and square kilometers), name, downstream hydrologic unit code, type of watershed, non-contributing areas, and flow modifications. The HUC describes where the unit is in the country and the level of the unit. WBD line attributes contain the highest level of hydrologic unit for each boundary, line source information and flow modifications.

description: This dataset is intended to be used as a tool for water-resource management and planning activities, particularly for site-specific and localized studies requiring a level of detail provided by large-scale map information.; abstract: This dataset is intended to be used as a tool for water-resource management and planning activities, particularly for site-specific and localized studies requiring a level of detail provided by large-scale map information.

This layer is a component of Geology & Geography.

This dataset was created using the 123 PISCES extant species range layers listed below in the table. The PISCES datasets were converted to rasters using GIS and then map algebra was used to calculate the total number of species in each huc12 watershed. Using GIS, an extended table was created to provide species lists by watershed using a one to many table relate. Species presence data was provided by PISCES: Moyle, Quinones and Bell (direct addition), Moyle and Randall (gstpoly), . These layers were generated by PISCES on 10/30/2014. The datasets listed in the table below were used in this analysis.Pisces_CodeCommon_NameAAM01Northern Green SturgeonAAT01White sturgeonCCF01Owens SuckerCCO02Goose Lake SuckerCCS01Klamath Largescale SuckerCCA03Clear Lake Prickly SculpinCCG01Riffle SculpinCCK03Upper Klamath Marbled SculpinCCK01Bigeye Marbled SculpinCCK02Lower Klamath Marbled SculpinCCN02Amargosa River PupfishCCN01Saratoga Springs PupfishCCN04Shoshone PupfishCCS03Salt Creek PupfishPEF01Northern California Brook LampreyPES01Klamath River LampreyPET02Goose Lake LampreyPET01Pacific LampreyCGC01Blue ChubCGO01Arroyo ChubEHT03Clear Lake Tule PerchEHT02Russian River Tule PerchEHT01Sacramento Tule PerchPLH01Kern Brook LampreyPLL01Pit-Klamath Brook LampreyPLR01Western Brook LampreyCLE01Sacramento HitchCLE03Monterey HitchCLP01Gualala RoachCLS06Navarro RoachCLS05Monterey RoachCLS04Clear Lake RoachCLS02Red Hills RoachCLS03Russian River RoachCLS07Tomales RoachCLS01Central California RoachCMC01HardHeadSOC01Coastal Cutthroat TroutSOM03Klamath Mountains Province Winter SteelheadSOM04Klamath Mountains Province Summer SteelheadSOM14California Golden TroutSOM12Eagle Lake Rainbow TroutSOM13Kern River Rainbow TroutSOM10McCloud River Redband TroutSOM11Goose Lake Redband TroutSOT08Central Valley Fall Chinook SalmonSOT07Central Valley Late Fall Chinook SalmonSOT03Southern Oregon Northern California Coast Fall Chinook SalmonSOT01Upper Klamath-Trinity Fall Chinook SalmonSOT02Upper Klamath-Trinity Spring Chinook SalmonCCP01Lahontan Mountain SuckerCPM01Sacramento SplittailSPW01Mountain WhitefishCRO06Amargosa Canyon Speckled DaceCRO05Long Valley Speckled DaceCRO04Owens Speckled DaceCRO07Santa Ana Speckled DaceCSB03Lahontan Lake Tui ChubCSB05Eagle Lake Tui ChubCST01Goose Lake Tui ChubCST03Cow Head Tui ChubAAM02Southern Green SturgeonCCL01Lost River SuckerCCM01Modoc SuckerCCO04Humboldt SuckerCCO03Monterey SuckerCCO01Sacramento SuckerCCR01Klamath Smallscale SuckerCCS02Santa Ana SuckerCCT01Tahoe SuckerCCB01Shortnose SuckerCCA04Coastrange SculpinCCA02Prickly SculpinCCA01Rough SculpinCCB02Paiute SculpinCCP03Reticulate SculpinCCP02Pit SculpinCCM02Desert PupfishCCR02Owens PupfishCCS04Cottonball Marsh PupfishGEN01Tidewater GobyCFP01California KillfishGGA01Coastal Threespine SticklebackGGA02Inland Threespine SticklebackGGA04Santa Ana (Shay Creek) SticklebackGGA03Unarmored Threespine SticklebackOHP01Delta SmeltPLA01River LampreyCLE02Clear Lake HitchCLS08Northern (Pit) RoachCLA01Staghorn SculpinMMC02Striped MulletSOC03Lahontan Cutthroat TroutSOC02Paiute Cutthroat TroutSOG01Pink SalmonSOK03Chum SalmonSOK01Central Coast Coho SalmonSOK02Southern Oregon Northern California Coast Coho SalmonSOM05Central California Coast Winter SteelheadSOM06Central Valley SteelheadSOM02Northern California Coast Summer SteelheadSOM01Northern California Coast Winter SteelheadSOM07South Central California Coast SteelheadSOM08Southern California SteelheadSOM09Coastal Rainbow TroutSOM15Little Kern Golden TroutSOT04California Coast Fall Chinook SalmonSOT06Central Valley Spring Chinook SalmonSOT05Central Valley Winter Chinook SalmonCOM01Sacramento BlackfishPPS01Starry FlounderCPG01Sacramento PikeminnowCRO03Klamath Speckled DaceCRO02Lahontan Speckled DaceCRO01Sacramento Speckled DaceCRE01Lahontan RedsideCSB01Klamath Tui ChubCSB04Lahontan Stream Tui ChubCSB06Owens Tui ChubCST02Pit River Tui ChubOST01Longfin SmeltOTP01EulachonCXT01Razorback Sucker

This mapping tool provides a representation of the general watershed boundaries for stream systems declared fully appropriated by the State Water Board. The boundaries were created by Division of Water Rights staff by delineating FASS critical reaches and consolidating HUC 12 sub-watersheds to form FASS Watershed boundaries. As such, the boundaries are in most cases conservative with respect to the associated stream system. However, users should check neighboring FASS Watersheds to ensure the stream system of interest is not restricted by other FASS listings. For more information regarding the Declaration of Fully Appropriated Stream Systems, visit the Division of Water Rights’ Fully Appropriated Streams webpage. How to Use the Interactive Mapping Tool: If it is your first time viewing the map, you will need to click the “OK” box on the splash screen and agree to the disclaimer before continuing. Navigate to your point of interest by either using the search bar or by zooming in on the map. You may enter a stream name, street address, or watershed ID in the search bar. Click on the map to identify the location of interest and one or more pop-up boxes may appear with information about the fully appropriated stream systems within the general watershed boundaries of the identified location. The information provided in the pop-up box may include: (a) stream name, (b) tributary, (c) season declared fully appropriated, (d) Board Decisions/Water Right Orders, and/or (e) court references/adjudications. You may toggle the FAS Streams reference layer on and off to find representative critical reaches associated with the FASS Watershed layer. Please note that this layer is for general reference purposes only and ultimately the critical reach listed in Appendix A of Water Rights Order 98-08 and Appendix A together with any associated footnotes controls. Note: A separate FAS Watershed boundary layer was created for the Bay-Delta Watershed. The Bay-Delta Watershed layer should be toggled on to check if the area of interest is fully appropriated under State Water Board Decision 1594.

CDFW BIOS GIS Dataset, Contact: Diane Mastalir, Description: This data set is an extract of the California Watershed (calwater) dataset. It has been generalized to hydrologic sub-areas for those watersheds that are considered part of the coastal steelhead trout range.

California Watershed Map: Version 2.2. This layer is composed of polygons at depict the boundary of the various watershed areas in Napa County.

The USGS National Hydrography Dataset (NHD) downloadable data collection from The National Map (TNM) is a comprehensive set of digital spatial data that encodes information about naturally occurring and constructed bodies of surface water (lakes, ponds, and reservoirs), paths through which water flows (canals, ditches, streams, and rivers), and related entities such as point features (springs, wells, stream gages, and dams). The information encoded about these features includes classification and other characteristics, delineation, geographic name, position and related measures, a "reach code" through which other information can be related to the NHD, and the direction of water flow. The network of reach codes delineating water and transported material flow allows users to trace movement in upstream and downstream directions. In addition to this geographic information, the dataset contains metadata that supports the exchange of future updates and improvements to the data. The NHD supports many applications, such as making maps, geocoding observations, flow modeling, data maintenance, and stewardship. For additional information on NHD, go to https://www.usgs.gov/core-science-systems/ngp/national-hydrography.

DWR was the steward for NHD and Watershed Boundary Dataset (WBD) in California. We worked with other organizations to edit and improve NHD and WBD, using the business rules for California. California's NHD improvements were sent to USGS for incorporation into the national database. The most up-to-date products are accessible from the USGS website. Please note that the California portion of the National Hydrography Dataset is appropriate for use at the 1:24,000 scale.

For additional derivative products and resources, including the major features in geopackage format, please go to this page: https://data.cnra.ca.gov/dataset/nhd-major-features Archives of previous statewide extracts of the NHD going back to 2018 may be found at https://data.cnra.ca.gov/dataset/nhd-archive.

In September 2022, USGS officially notified DWR that the NHD would become static as USGS resources will be devoted to the transition to the new 3D Hydrography Program (3DHP). 3DHP will consist of LiDAR-derived hydrography at a higher resolution than NHD. Upon completion, 3DHP data will be easier to maintain, based on a modern data model and architecture, and better meet the requirements of users that were documented in the Hydrography Requirements and Benefits Study (2016). The initial releases of 3DHP include NHD data cross-walked into the 3DHP data model. It will take several years for the 3DHP to be built out for California. Please refer to the resources on this page for more information.

The FINAL,STATIC version of the National Hydrography Dataset for California was published for download by USGS on December 27, 2023. This dataset can no longer be edited by the state stewards. The next generation of national hydrography data is the USGS 3D Hydrography Program (3DHP).

Questions about the California stewardship of these datasets may be directed to nhd_stewardship@water.ca.gov.

This landuse / landcover (LULC) map displays a basic depiction of the Los Planes watershed in Baja California Sur, Mexico. This simplified, 7-class LULC map displays classes that are useful for hydrologic modeling and broad vegetation mapping in the region. It was created from analysis of six Sentinel-2 satellite images and other existing geospatial datasets. These satellite images are provided at 10-meter spatial resolution and were calibrated for topographic illumination effects to enhance its accuracy in rugged, mountainous terrain like that seen in the watershed. A novel filtering methodology was also applied to minimize the "salt-and-pepper effect" from the principle component analysis (PCA) and image classification methodology. See "lulc_los_planes_watershed_final_2_legend.jpg" for a low-resolution overview of the image and legend.

The USGS, in cooperation with the U.S. Bureau of Land Management (BLM), created a series of geospatial products of the Scotts Creek Watershed in Lake County, California, using National Agriculture Imagery Program (NAIP) imagery from 2022 and Open Street Map (OSM) from 2019. The imagery was downloaded from United States Department of Agriculture (USDA) - Natural Resources Conservation Service (NRCS) Geospatial Data Gateway (https://datagateway.nrcs.usda.gov/) and Geofabrik GmbH - Open Street Map (https://www.geofabrik.de/geofabrik/openstreetmap.html), respectively. An updated trail map for the Upper Scotts Creek Watershed, including the BLM Recreational Area, was created to estimate trail densities in the watershed. A preview image of the roads and trail maps is attached to this data release (see UpperScottsCreek_Roads_and_Trails_Map_2022_USGS2022_CC0.png).

The Eel River CZO operates on several spatial scales from a zero order hillslope to the entire Eel River on the north coast of California. Rivendell, Angelo, Sagehorn, South Fork, and Eel River GIS boundaries. GIS polygon shapefiles. All files are in geographic projection (Lat/Long) with a datum of WGS84.

The watershed boundaries are from USGS Watershed Boundary Dataset (WBD) http://nhd.usgs.gov/wbd.html. Rivendell and Angelo boundaries are created from LiDAR by the CZO. Sagehorn Ranch is a privately held, active commercial ranch with no public access. Please contact the CZO if you are interested in data from Sagehorn Ranch.

Shapefiles

Eel River Watershed (drainage area 9534 km^2): Entire eel river. Greatest extent of CZO research.

South Fork Eel Watershed (drainage area 1784 km^2).

Angelo Reserve Boundary (30.0 km^2): Angelo Coast Range Reserve is a University of California Natural Reserve System protected land. It is the central focus of CZO research. http://angelo.berkeley.edu

Sagehorn Ranch Boundary (21.1 km^2): Sagehorn Ranch is a private ranch with active cattle raising. The owners have allowed the CZO to place instrumentation on their lands. Access is only by explicit agreement by owners.

Rivendell Cachement (0.0076 km^2): Rivendell is a small, heavily instrumented hillslope within the Angelo Reserve. It has roughly 700 instruments deployed as of 2016. Data is online at http://sensor.berkeley.edu

This polygon shapefile depicts a dissolve that was run on the Hydrologic Sub Areas for the nine county San Francisco Bay Area Region, California. Hydrologic Sub Areas are those ranging in size from 195-243 square miles or 125,000-155,999 acres (Myers & Peltz-Lewis, 2004). This data was derived from the California Watershed Map (CalWater version 2.2), a set of standardized watershed boundaries meeting standardized delineation criteria. The hierarchy of watershed designations consists of six levels of increasing specificity: Hydrologic Region (HR), Hydrologic Unit (HU), Hydrologic Area (HA), Hydrologic Sub Area (HSA), Super Planning Watershed (SPWS) and Planning Watershed (PWS). The primary purpose of CalWater is the assignment of a single, unique code to a specific watershed polygon. Watersheds are useful for many aspects of the Project, including development of watershed integrity analysis. These data were critical for the Fish and Riparian Focus Team portion of the Project.

This polygon shapefile depicts a dissolve that was run on the planning watersheds for the nine county San Francisco Bay Area Region, California. Planning Watersheds are those ranging in size from 5-79 square miles or 3,000-49,999 acres (Myers & Peltz-Lewis, 2004). This data was derived from the California Watershed Map (CalWater version 2.2), a set of standardized watershed boundaries meeting standardized delineation criteria. The hierarchy of watershed designations consists of six levels of increasing specificity: Hydrologic Region (HR), Hydrologic Unit (HU), Hydrologic Area (HA), Hydrologic Sub Area (HSA), Super Planning Watershed (SPWS), and Planning Watershed (PWS). The primary purpose of CalWater is the assignment of a single, unique code to a specific watershed polygon. Watersheds are useful for many aspects of the Project, including development of watershed integrity analysis. These data were critical for the Fish and Riparian Focus Team portion of the Project.

This raster dataset contains topographic hillshade for the Elk River watershed in Humboldt County, California. This dataset is the product of the Department of Conservation, California Geological Survey’s (CGS) investigation of landslides in the Elk River watershed. The 52 square mile study area is located in Humboldt County in northwestern California. The investigation was based on interpretation of 1940, 1941, 1948, 1954, 1962, 1965, 1984, 1988, 1996 and 2000 aerial photos, findings from CGS’s landslide mapping conducted in the early 1980s (Kilbourne, R.T. 1982-84, Manson, M. W. 1984), as well as other sources. Mapping was conducted at 1:24,000 scale. The resulting maps are titled “Geologic and Geomorphic Features Related to Landsliding, Elk River Watershed” (Plate 1) and “Relative Landslide Potential with Geologic and Geomorphic Features, Elk River Watershed” map (Plate 2). This study was conducted at a regional scale of mapping using ten sets of aerial photos combined with a compilation of earlier published and unpublished work. Other photo sets may reveal additional landslides. The regional nature of the study makes the data and maps, including the relative landslide potential zones, inappropriate as a substitute for site-specific analysis.

The maps/data are useful in preparation of Timber Harvesting Plans, and for use by land managers for identifying areas of potentially unstable ground. The maps/data serve as a guide to potential problem areas where more site-specific review is required.

This subset of the USGS Water Boundary Dataset contains the polygons of the 50 8-digit Hydrologic Units that comprise the greater Central Valley study site. The Watershed Boundary Dataset is a comprehensive set of digital spatial data that represents the surface drainages areas of the United States. The information included with the features includes a feature date, a unique common identifier, name, the feature length or area, and other characteristics. Names and their identifiers are assigned from the Geographic Names Information System. The data also contains relations that encode metadata. The names and definitions of all these feature attributes are in the Federal Standards and Procedures for the National Watershed Boundary Dataset (WBD). The document is available online at https://pubs.usgs.gov/tm/11/a3/