This digital dataset contains groundwater level observations for 364 wells, in addition to well construction information, from 1916 to 2014 in the Central Valley, California. Groundwater level observations are used to create groundwater level contours and to calibrate the groundwater levels for the updated Central Valley Hydrologic Model (CVHM2). Groundwater level observations were collected from five sources (USGS, 2018; SLDMWA, 2018; CADWR, 2004; CRNA, 2018).

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This dataset depicts groundwater level (expressed as elevation) at selected monitoring locations (wells), by season and year. Other information on the monitoring location is also included. Water level monitoring locations and measurements used are selected based on measurement date and well construction information, where available, and approximate groundwater levels in the unconfined to uppermost semi-confined aquifers.

The DWR Periodic Groundwater Levels dataset contains seasonal and long-term groundwater level measurements collected by the Department of Water Resources and cooperating agencies in groundwater basins statewide. It also includes data collected through the Sustainable Groundwater Management Act (SGMA) Portal’s Monitoring Network Module (MNM), and the CASGEM (California Statewide Groundwater Elevation Monitoring) Program. Most measurements are taken manually twice per year to capture the peak high and low values in groundwater elevations. However, the dataset also includes measurements recorded more frequently, monthly, weekly, or daily. This resource also included daily measurements from DWR's automated monitoring network of groundwater sites. For DWRs holdings of groundwater level measurements recorded at more frequent intervals (e.g., hourly), please refer to DWR's “Continuous Groundwater Level Measurements” dataset. For additional information regarding DWR groundwater levels data collection please visit DWR's Groundwater Management website (https://www.water.ca.gov/Programs/Groundwater-Management). The source data can also be accessed directly from two websites. The Water Data Library (http://wdl.water.ca.gov) provides anonymous access to this and other data sets. The CASGEM online system (https://www.casgem.water.ca.gov/OSS) provides authenticated access to only the the periodic groundwater measurements. This dataset is maintained primarily in the DWR Enterprise Water Management database and contains information specific to the location of groundwater level monitoring wells and groundwater level measurements collected at these wells. The Stations resource identifies well location coordinates and other supplementary items about the well type. Measurements resources includes information about the time/date a measurement was collected, the entity collecting the measurement, a measurement indicating the depth to groundwater, and quality information about the measurement. The Well Perforations resources contains well construction information identifying the well's screened intervals (not available for all wells).

This digital dataset includes three sets of observational data (groundwater level, streamflow, subsidence) used to calibrate the updated Central Valley Hydrologic Model (CVHM2). CVHM2 is a tool that can be used to quantify the sustainability of groundwater resources in the Central Valley.

This dataset depicts groundwater level (expressed as elevation) at selected monitoring locations (wells), by season and year. Other information on the monitoring location is also included. Water level monitoring locations and measurements used are selected based on measurement date and well construction information, where available, and approximate groundwater levels in the unconfined to uppermost semi-confined aquifers.

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This dataset depicts groundwater level (expressed as elevation in feet amsl) at selected monitoring locations (wells) , by season and year. Other information on the monitoring location is also included. Water level monitoring locations and measurements used are selected based on measurement date and well construction information, where available, and approximate groundwater levels in the unconfined to uppermost semi-confined aquifers. This dataset was created to assist state and local agencies in assessing the status of groundwater levels statewide for recent seasons/years and in relation to other periods. For more information on this service, please contact gis@water.ca.gov

This dataset depicts groundwater level (expressed as elevation in feet amsl) at selected monitoring locations (wells) , by season and year. Other information on the monitoring location is also included. Water level monitoring locations and measurements used are selected based on measurement date and well construction information, where available, and approximate groundwater levels in the unconfined to uppermost semi-confined aquifers. This dataset was created to assist state and local agencies in assessing the status of groundwater levels statewide for recent seasons/years and in relation to other periods. For more information on this service, please contact gis@water.ca.gov

This digital dataset defines the well locations for hydraulic-head observations used in the calibration of the transient hydrologic model of the Central Valley flow system. The Central Valley encompasses an approximate 50,000 square-kilometer region of California. The complex hydrologic system of the Central Valley is simulated using the USGSs numerical modeling code MODFLOW-FMP (Schmid and others, 2006). This application is referred to here as the Central Valley Hydrologic Model (CVHM) (Faunt, 2009). Utilizing MODFLOW-FMP, the CVHM simulates groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis from 1961-2003. The USGS and DWR maintain databases of key wells in the Central Valley that are web-accessible (http://waterdata.usgs.gov and http://www.water.ca.gov/waterdatalibrary/, respectively). These data were combined to form a database of available water levels throughout the Central Valley from 1961 to 2003. More than 850,000 water-level altitude measurements from more than 21,400 wells have been compiled by the USGS or DWR and have been entered into their respective databases. However, only a small proportion of these wells have both sufficient construction information to determine the well-perforation interval and water-level measurements for the simulation period. For model calibration, water-level altitude data were needed that were (1) distributed spatially (both geographically and vertically) throughout the Central Valley, from the valley trough to the foothills; (2) distributed temporally throughout the simulation period (1961-2003); and (3) available during both wet and dry climatic regimes. From the available wells records, a subset of comparison wells was selected on the basis of perforation depths, completeness of record, climatic intervals, and locations throughout the Central Valley. Water-level altitude observations (19,725) for 206 comparison wells were used as calibration targets during parameter estimation. The CVHM is the most recent regional-scale model of the Central Valley developed by the U.S. Geological Survey (USGS).The CVHM was developed as part of the USGS Groundwater Resources Program (see "Foreword", Chapter A, page iii, for details).