Data provided here describe the contribution of up to 7 different water sources to the major ion geochemistry of U.S. Geological Survey (USGS) and California State Water Resources Control Board Division of Drinking Water (CA-DDW) groundwater samples within the Indio Subbasin of the Coachella Valley, California. The Inverse Geochemical Modeling was performed in the USGS's PHREEQC ver. 3 program and the results are discussed in the associated publication of Harkness and others (2023). Datasets include the major ion chemistry and model input parameters of 1593 samples included in the analysis, the median model results for each sample, and a data dictionary describing the tables. Analyses completed as part of this assessment relied on the previously published data of Harkness (2022) and no new data were collected.

The U.S. Geological Survey collected groundwater samples from 17 wells in the Indio subbasin (CA basin designation 7-21.01) of the Coachella Valley and surface water samples from two sites representing sources of recharge to the Indio subbasin in 2021. These samples are intended to provide inorganic water quality data, particularly total dissolved solids (TDS), within areas of the Indio subbasin not sampled for the Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project’s assessment of the quality of groundwater used for domestic and small system drinking water supplies in Coachella Valley (CODA). Other areas of special interest for the Indio salinity study were nearby managed aquifer replenishment facilities. Various well types were sampled including domestic, public supply, irrigation, and monitoring wells. The two surface water samples were collected in order to better understand primary sources of recharge to the Indio subbasin: the Whitewater River and the Colorado River via the Coachella Canal. Groundwater samples from all 17 wells were analyzed for field water-quality parameters, major ions and trace elements, chromium (VI), perchlorate, nutrients, carbon-14 in dissolved inorganic carbon, stable isotopic ratios of water, tritium, isotopes of sulfur in sulfate, sulfur hexafluoride, and noble gases. Groundwater levels were measured in 9 of the 17 wells. Surface water samples from both sites were analyzed for field water-quality parameters, major ions and trace elements, chromium (VI), perchlorate, nutrients, and stable isotopic ratios of water. All results are presented in this data release except for the isotopic ratios of strontium and boron in water. Data collected from 23 wells sampled in the Indio subbasin for the CODA assessment are not included in this data release but can be found here: https://doi.org/10.5066/P9UYXI95

The U.S. Geological Survey collected groundwater samples from 17 wells in the Indio subbasin (CA basin designation 7-21.01) of the Coachella Valley and surface water samples from two sites representing sources of recharge to the Indio subbasin in 2021. These samples are intended to provide inorganic water quality data, particularly total dissolved solids (TDS), within areas of the Indio subbasin not sampled for the Groundwater Ambient Monitoring and Assessment (GAMA) Program Priority Basin Project’s assessment of the quality of groundwater used for domestic and small system drinking water supplies in Coachella Valley (CODA). Other areas of special interest for the Indio salinity study were nearby managed aquifer replenishment facilities. Various well types were sampled including domestic, public supply, irrigation, and monitoring wells. The two surface water samples were collected in order to better understand primary sources of recharge to the Indio subbasin: the Whitewater River and the Colorado River via the Coachella Canal. Groundwater samples from all 17 wells were analyzed for field water-quality parameters, major ions and trace elements, chromium (VI), perchlorate, nutrients, carbon-14 in dissolved inorganic carbon, stable isotopic ratios of water, tritium, isotopes of sulfur in sulfate, sulfur hexafluoride, and noble gases. Groundwater levels were measured in 9 of the 17 wells. Surface water samples from both sites were analyzed for field water-quality parameters, major ions and trace elements, chromium (VI), perchlorate, nutrients, and stable isotopic ratios of water. All results are presented in this data release except for the isotopic ratios of strontium and boron in water. Data collected from 23 wells sampled in the Indio subbasin for the CODA assessment are not included in this data release but can be found here: https://doi.org/10.5066/P9UYXI95

Groundwater salinity presents a challenge to the management of water quality in the Indio subbasin of the Coachella Valley where a growing population is dependent primarily on groundwater for drinking water. The U.S. Geological survey, along with the Colorado River Basin regional water quality control board, are working to provide an assessment of salinity trends and sources in the Indio subbasin (California (CA) basin designation 7-21.01; California Department of Water Resources (2020)). As part of this work, salinity data and other selected inorganic water quality data, along with well construction information, for wells with available total dissolved solids (TDS) or conductance data were compiled from published reports, public databases, and unpublished archives into a tabulated spreadsheet. This spreadsheet represents a synthesis of available data on groundwater salinity in the Coachella Valley, however it does not include all data ever published in the region.

Groundwater salinity presents a challenge to the management of water quality in the Indio subbasin of the Coachella Valley where a growing population is dependent primarily on groundwater for drinking water. The U.S. Geological survey, along with the Colorado River Basin regional water quality control board, are working to provide an assessment of salinity trends and sources in the Indio subbasin (California (CA) basin designation 7-21.01; California Department of Water Resources (2020). As part of this work, salinity data and other selected inorganic water quality data, along with well construction information, for wells with available total dissolved solids (TDS) or conductance data were compiled from published reports, public databases, and unpublished archives into a tabulated file, Indio_data_v2.txt. The database in this data release represents a synthesis of available data on groundwater salinity in the Coachella Valley, however it does not include all data ever published in the region. This database was updated in March, 2025 to include salinity data collected from groundwater samples through the year 2024. Version History Summary: First Published: July 2022 Version 2.0: July 2025

These data (vector and raster) were compiled for spatial modeling of salinity yield sources in the Upper Colorado River Basin (UCRB) and describe different scales of watersheds in the Upper Colorado River Basin (UCRB) for use in salinity yield modeling. Salinity yield refers to how much dissolved salts are picked up in surface waters that could be expected to be measured at the watershed outlet point annually. The vector polygons are small catchments developed originally for use in SPARROW modeling that break up the UCRB into 10,789 catchments linked together through a synthetic stream network. The catchments were used for a machine learning based salinity model and attributed with the new results in these vector GIS datasets. Although all of these feature classes include the same polygons, the attribute tables for each include differing outputs from new salinity models and a comparison with SPARROW model results from previous research. The new model presented in these datasets utilizes new predictive soil maps and a more flexible random forest function to improve on previous UCRB salinity spatial models. The raster data layers represent aspects of soils, topography, climate, and runoff characteristics that have hypothesized influences on salinity yields.

These data (vector and raster) were compiled for spatial modeling of salinity yield sources in the Upper Colorado River Basin (UCRB) and describe different scales of watersheds in the Upper Colorado River Basin (UCRB) for use in salinity yield modeling. Salinity yield refers to how much dissolved salts are picked up in surface waters that could be expected to be measured at the watershed outlet point annually. The vector polygons are small catchments developed originally for use in SPARROW modeling that break up the UCRB into 10,789 catchments linked together through a synthetic stream network. The catchments were used for a machine learning based salinity model and attributed with the new results in these vector GIS datasets. Although all of these feature classes include the same polygons, the attribute tables for each include differing outputs from new salinity models and a comparison with SPARROW model results from previous research. The new model presented in these datasets utilizes new predictive soil maps and a more flexible random forest function to improve on previous UCRB salinity spatial models. The raster data layers represent aspects of soils, topography, climate, and runoff characteristics that have hypothesized influences on salinity yields.

This digital dataset contains the datasets related to agricultural and municipal water supply and groundwater in the Lower Salinas Valley Hydrologic Models (LSVHM), including the Salinas Valley Operational Model (SVOM) and the Salinas Valley Integrated Hydrologic Model (SVIHM). Groundwater inflow and outflow data include reported groundwater pumpage and groundwater elevations obtained for the period from October 1, 1967, to September 30, 2018. Groundwater pumpage in the Lower Salinas Valley Hydrologic Models is grouped into (1) pre-estimated and specified municipal and industrial (referred to as water supply) and (2) simulated pumpage from all irrigation wells used to supply water for irrigation (referred to as agricultural supply). Groundwater pumpage is provided in units of acre-feet per month for each water balance subregion (Henson and Jachens, 2022). Groundwater pumpage was defined by water supply wells and agricultural supply wells. Additionally, water levels from wells were used to evaluate groundwater levels in the simulation. To support the agricultural water demand and supply estimates, surface water diversions and non-routed delivery are included for the water-balance subregions (WBS) that receive surface water for irrigation. To support the evaluation of groundwater levels in the Lower Salinas Valley Hydrologic Models, this data release includes groundwater-level contour maps and groundwater level time series for wells used to define head-dependent flow boundaries in water balance subregions 5 and 6 in the northwestern coastal area in the Lower Salinas Valley Hydrologic Models. Water-level maps were provided by the Monterey County Water Resources Agency (MCWRA) for fall of 1994, 2003, and 2011 for a composite of shallow aquifers (<201 feet below land surface) and deep aquifers (>201 to 420 feet below land surface). These contours can be used for spatial comparison of the model-simulated groundwater values with observed data. Head-dependent flow boundaries were simulated using the General Head Boundary Package (GHB) of MODFLOW (Harbaugh, 2005) and are implemented to represent lateral groundwater underflow. Citations: Harbaugh, A.W., 2005. MODFLOW-2005, the U.S. Geological Survey modular ground-water model-the Ground-Water Flow Process: U.S. Geological Survey Techniques and Methods 6-A16, https://doi.org/10.3133/tm6A16. Henson, W.R., and Jachens, E.R., 2022, Lower Salinas Valley Hydrologic Models: Discretization Data: U.S. Geological Survey data release. https://doi.org/10.5066/P9850MAK.

This digital dataset contains the datasets related to agricultural and municipal water supply and groundwater in the Lower Salinas Valley Hydrologic Models (LSVHM), including the Salinas Valley Operational Model (SVOM) and the Salinas Valley Integrated Hydrologic Model (SVIHM). Groundwater inflow and outflow data include reported groundwater pumpage and groundwater elevations obtained for the period from October 1, 1967, to September 30, 2018. Groundwater pumpage in the Lower Salinas Valley Hydrologic Models is grouped into (1) pre-estimated and specified municipal and industrial (referred to as water supply) and (2) simulated pumpage from all irrigation wells used to supply water for irrigation (referred to as agricultural supply). Groundwater pumpage is provided in units of acre-feet per month for each water balance subregion (Henson and Jachens, 2022). Groundwater pumpage was defined by water supply wells and agricultural supply wells. Additionally, water levels from wells were used to evaluate groundwater levels in the simulation. To support the agricultural water demand and supply estimates, surface water diversions and non-routed delivery are included for the water-balance subregions (WBS) that receive surface water for irrigation. To support the evaluation of groundwater levels in the Lower Salinas Valley Hydrologic Models, this data release includes groundwater-level contour maps and groundwater level time series for wells used to define head-dependent flow boundaries in water balance subregions 5 and 6 in the northwestern coastal area in the Lower Salinas Valley Hydrologic Models. Water-level maps were provided by the Monterey County Water Resources Agency (MCWRA) for fall of 1994, 2003, and 2011 for a composite of shallow aquifers (<201 feet below land surface) and deep aquifers (>201 to 420 feet below land surface). These contours can be used for spatial comparison of the model-simulated groundwater values with observed data. Head-dependent flow boundaries were simulated using the General Head Boundary Package (GHB) of MODFLOW (Harbaugh, 2005) and are implemented to represent lateral groundwater underflow. Citations: Harbaugh, A.W., 2005. MODFLOW-2005, the U.S. Geological Survey modular ground-water model-the Ground-Water Flow Process: U.S. Geological Survey Techniques and Methods 6-A16, https://doi.org/10.3133/tm6A16. Henson, W.R., and Jachens, E.R., 2022, Lower Salinas Valley Hydrologic Models: Discretization Data: U.S. Geological Survey data release. https://doi.org/10.5066/P9850MAK.

This model archive contains the datasets, procedures, and necessary program code used to describe the Salinas Valley Watershed Model (SVWM). The SVWM simulates the daily historical water balance and hydrologic conditions for the Salinas Valley study area including the many un-gaged tributary subdrainages in the rugged and mountainous upland areas surrounding flat-lying valley lowlands coinciding with developed areas including croplands irrigated with groundwater. The SVWM simulates the natural hydrologic system for the entire Salinas Valley watershed and adjacent coastal basins, excluding anthropogenic components such as pumping, diversions, irrigation, and reservoir operations, for the 70 years beginning October 1, 1948, and ending September 30, 2022. The SVWM uses two modeling applications; the Hydrologic Simulation Program – Fortran (HSPF, version 12.4; U.S. Environmental Protection Agency, 2000) to simulate the natural hydrologic system (Bicknell and others., 2005) and the Basin Characterization Model (BCM; Flint and others, 2021) to develop spatially distributed, historical climate inputs for HSPF. The HSPF application simulates the daily surface water and shallow subsurface water storage and flow processes, including interception storage and evaporation on vegetation, surface retention storage and evaporation, pervious land soil water storage and evapotranspiration, runoff from impervious and pervious land areas, streamflow, recharge from pervious land areas, and recharge from streamflow seepage. Climate inputs developed using the BCM are daily precipitation, daily maximum and minimum air temperature, and daily potential evapotranspiration (PET) (Hevesi and others, 2022). SVWM parameters were estimated using geospatial data and then adjusted by trial-and-error fitting of simulated daily streamflow to long-term records of observed streamflow at 29 U.S. Geological Survey stream gages (U.S. Geological Survey, 2016) and to estimated daily surface water inflows to Nacimiento and San Antonio Reservoirs (Henson and others, 2022a). The trial-and-error calibration provided a good match between simulated and observed daily, monthly, mean-monthly, and annual streamflow. The simulated output components from the SVWM include evapotranspiration, land area runoff (overland flow, interflow, baseflow), recharge, and groundwater recharge for the 690 HRUs, as well as streamflow and stream seepage losses for the 690 stream reaches connecting the HRUs.