Stations and a table of download links for time-series data, from DWR's continuous environmental monitoring database. For more information, see DWR's Water Data Library, continuous data section: https://wdl.water.ca.gov/ContinuousData.aspx, where this data is also available.

The California Department of Water Resources (DWR) discrete (vs. continuous) water quality datasets contains DWR-collected, current and historical, chemical and physical parameters found in routine environmental, regulatory compliance monitoring, and special studies throughout the state.

DWR continuous groundwater level measurements contains continuous time-series data from automated recorders at sites operated by the Department of Water Resources. Readings are taken at 15-minute to one-hour intervals. Some of the readings are relayed to the California Data Exchange Center. However, most of the monitoring sites are visited once every month or two, when readings are off-loaded from data recorders, then finalized and published. Wells monitored for this dataset are located within Butte, Colusa, Glenn, Mendocino, Modoc, Sacramento, San Joaquin, Shasta, Siskiyou, Solano, Sutter, Tehama, Yolo, and Yuba Counties. Water-level measurements are the principal source of information about changes in groundwater storage and movement in a basin, and how these are affected by various forms of recharge (e.g., precipitation, seepage from streams, irrigation return) and discharge (e.g., seepage to streams, groundwater pumping). Water-level monitoring involves "continuous" or periodic measurements. Continuous monitoring makes use of automatic water-level sensing and recording instruments that are programmed to make scheduled measurements in wells. This provides a high-resolution record of water-level fluctuations. Resulting hydrographs can accurately identify the effects of various stresses on the aquifer system and provide measurements of maximum and minimum water levels in aquifers. Continuous monitoring may be the best technique to use for monitoring fluctuations in groundwater levels during droughts and other critical periods when hydraulic stresses may change at relatively rapid rates, or when real-time data are needed for making water management decisions [see usgs reference](https://ca.water.usgs.gov/sustainable-groundwater-management/groundwater-levels-california.html).

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).

Discrete water quality monitoring data from the Sacramento-San Joaquin Bay-Delta collected by the Environmental Monitoring Program. Data is also accessible via the [Environmental Data Initiative](https://portal.edirepository.org/nis/mapbrowse?scope=edi&identifier=458&revision=10).