A critical aspects of the uniqueness of coastal drought is the effects on salinity dynamics of creeks and rivers. The location of the freshwater-saltwater interface along the coast is an important factor in the ecological and socio-economic dynamics of coastal communities. Salinity is a critical response variable that integrates hydrologic and coastal dynamics including streamflow, precipitation, sea level, tidal cycles, winds, and tropical storms. The position of the interface determines the composition of freshwater and saltwater aquatic communities as well as the freshwater availability for water intakes. Many definitions of drought have been proposed, with most describing a decline in precipitation which has a negative impacts on water supply. Indices have been developed incorporating data such as rainfall, streamflow, soil moisture, groundwater levels, and snow pack. These water availability drought indices were developed for upland areas and may not be ideal for characterizing coastal drought. The availability of real-time and historical salinity datasets provides an opportunity for the development of a salinity-based coastal drought index. The challenge for the salinity data analysis is to characterize the salinity dynamics in response to drought while excluding responses attributable to the occasional and (or) periodic saltwater intrusion events. An approach similar to the Standardized Precipitation Index was modified and applied to salinity data obtained from sites in South Carolina and Georgia. Evaluation of the coastal drought index indicates that the index can be used for different estuary types, for regional comparison, and as an index for wet (high freshwater inflow) and drought conditions. This data release will provide all the supporting data for the journal article including salinity datasets (with estimated missing values) and the computed indices.

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

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.

Model generated soil pore water salinity (psu) values under scenarios of drought and normal conditions at Tidal Freshwater Forested Wetlands (TFFW) sites along the Waccamaw River and Savannah River in the Southeastern United States.

Model generated soil pore water salinity (psu) values under scenarios of drought and normal conditions at Tidal Freshwater Forested Wetlands (TFFW) sites along the Waccamaw River and Savannah River in the Southeastern United States.

This digital dataset contains the baseline and future climate data used as the basis for analysis of current and future water supplies and demands in the Salinas and Carmel Rivers Basin Study (SCRBS). SCRBS uses a suite of integrated hydrologic models to explore impacts of future climate and socioeconomic scenarios on water supplies and demands in the basins. SCRBS considers one baseline climate scenario that represents recent historical climate conditions and five future climate scenarios that encompass the range of uncertainty in projections of future climate conditions through the end of the 21st century. The baseline scenario was developed by removing trends from an observed historical climate dataset such that the long-term monthly mean and variance over the full period of record (1931-2015) are consistent with observed historical averages over the baseline period (1980-2009). Future climate scenarios were developed by adjusting the baseline scenario to reflect projected changes in the distributions of monthly precipitation and temperature. The five future climate scenarios reflect the range of projected changes across an ensemble of statistically downscaled climate projections: Hot-Wet (HW), Warm-Wet (WW), Hot-Dry (HD), Warm-Dry (WD), and Central Tendency (CT). Analysis of future climate conditions was based on the Localized Constructed Analogues (LOCA) dataset, which includes statistically downscaled climate projections from global climate models (Pierce and others, 2014). Baseline and future climate scenarios were spatially downscaled from a native 1/16° grid to a 270-meter grid. The data set includes daily 270-meter gridded spatially distributed daily precipitation (PPT), maximum and minimum air temperature (TMX and TMN, respectively), and potential evapotranspiration (PET) from 1/1/2016 to 12/31/2100. Pierce, D. W., Cayan, D. R., and Thrasher, B. L., 2014, Statistical downscaling using Localized Constructed Analogs (LOCA): Journal of Hydrometeorology, v. 15, no. 6, p. 2558-2585, https://doi.org/10.1175/JHM-D-14-0082.1.

This digital dataset contains the baseline and future climate data used as the basis for analysis of current and future water supplies and demands in the Salinas and Carmel Rivers Basin Study (SCRBS). SCRBS uses a suite of integrated hydrologic models to explore impacts of future climate and socioeconomic scenarios on water supplies and demands in the basins. SCRBS considers one baseline climate scenario that represents recent historical climate conditions and five future climate scenarios that encompass the range of uncertainty in projections of future climate conditions through the end of the 21st century. The baseline scenario was developed by removing trends from an observed historical climate dataset such that the long-term monthly mean and variance over the full period of record (1931-2015) are consistent with observed historical averages over the baseline period (1980-2009). Future climate scenarios were developed by adjusting the baseline scenario to reflect projected changes in the distributions of monthly precipitation and temperature. The five future climate scenarios reflect the range of projected changes across an ensemble of statistically downscaled climate projections: Hot-Wet (HW), Warm-Wet (WW), Hot-Dry (HD), Warm-Dry (WD), and Central Tendency (CT). Analysis of future climate conditions was based on the Localized Constructed Analogues (LOCA) dataset, which includes statistically downscaled climate projections from global climate models (Pierce and others, 2014). Baseline and future climate scenarios were spatially downscaled from a native 1/16° grid to a 270-meter grid. The data set includes daily 270-meter gridded spatially distributed daily precipitation (PPT), maximum and minimum air temperature (TMX and TMN, respectively), and potential evapotranspiration (PET) from 1/1/2016 to 12/31/2100. Pierce, D. W., Cayan, D. R., and Thrasher, B. L., 2014, Statistical downscaling using Localized Constructed Analogs (LOCA): Journal of Hydrometeorology, v. 15, no. 6, p. 2558-2585, https://doi.org/10.1175/JHM-D-14-0082.1.

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

Since its formation, the Colorado River Basin Salinity Control Forum and its partners have completed a substantial amount of work in an ongoing effort to reduce salinity concentrations and loads in the Colorado River. These efforts and related monitoring have generated a large volume of data and information. This U.S. Geological Survey data release includes geospatial datasets that provide information on salinity-related topics and research in the Colorado River Basin. The datasets include background information and study-specific information. These datasets can be viewed in the accompanying interactive map, available at https://usgs.maps.arcgis.com/apps/webappviewer/index.html?id=a9728bc71f854e7da3e79632441b48a7.