Salinity levels in streams and tributaries of the Colorado River Basin have been a major concern for years. Recently, the United States Geological Survey’s (USGS) Next Generation Water Observing System (NGWOS) program expanded stream monitoring networks including the number of sites where continuous (15-minute) specific conductance is measured in the Colorado River Headwaters and Gunnison River subbasins located east of the Colorado-Utah state line (hereafter, UCOL). Salinity and total dissolved solids (TDS) can be estimated using specific conductance and water type as a proxy (McCleskey et al., 2023); thus, the UCOL is an ideal basin to apply the proxy. The data presented in this data release, including monitoring site information and water chemistry data, were used to develop a specific conductance and water type proxy model for salinity and TDS for sixty-six USGS monitoring sites in the UCOL. The monitoring site information and water-quality data for the sample sites in the UCOL were retrieved from the Water Quality Portal (Read et al., 2017) using the USGS dataRetrieval R package (De Cicco et al., 2018). The dataset contains 80,206 discrete water analyses collected between 1990 and 2023. The water chemistry data includes the concentrations of calcium, magnesium, sodium, potassium, chloride, sulfate, fluoride, nitrate, iron, boron, aluminum, alkalinity, and silica. A subset of this data includes 4,588 samples all of which have at least the concentrations of calcium, magnesium, sodium, potassium, chloride, and sulfate reported, a charge balance < ±10%, and a specific conductance imbalance < ±15%, unless the specific conductance was less than 100 µS/cm in which case the specific conductance difference was < ± 10 µS/cm. Finally, salinity and TDS were calculated for the discrete samples in the subset (McCleskey et al., 2023). References De Cicco, L.A., Hirsch, R.M., Lorenz, D. and Watkins, W.D., 2018. dataRetrieval: R packages for discovering and retrieving water data available from Federal hydrologic web services, doi:10.5066/P9X4L3GE. McCleskey, R.B., Cravotta, C.A., Miller, M.P., Tillman, F.D., Stackelberg, P., Knierim, K.J. and Wise, D., 2023. Salinity and total dissolved solids measurements for natural waters: An overview and a new salinity method based on specific conductance and water type. Applied Geochemistry, 154. Read, E.K., Carr, L., De Cicco, L., Dugan, H.A., Hanson, P.C., Hart, J.A., Kreft, J., Read, J.S. and Winslow, L.A., 2017. Water quality data for national-scale aquatic research: The Water Quality Portal. Water Resources Research, 53(2): 1735-1745

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.

The U.S Geological Survey (USGS), in cooperation with the Bureau of Reclamation (Reclamation), prepares a biennial analysis of salt loading at 20 sites on the Colorado River and its tributaries in Colorado, Wyoming, New Mexico, Utah, and Arizona. These estimates can also be used by Reclamation to measure the effectiveness of the Colorado River Basin Salinity Control Program. Data are retrieved from the publicly available USGS National Water Information System database and provided by Reclamation in the form of .pdf files that are compiled into Excel spreadsheets and included herein.

This data release contains total dissolved solids (TDS) concentrations and specific conductance (SC) measurements collected at surface-water monitoring locations and groundwater monitoring wells within the Upper Colorado River Basin (UCRB) between 1894 and 2022. Discrete TDS and SC results were obtained from the Water Quality Portal (WQP). Continuous SC monitoring results were obtained from the USGS National Water Information System (NWIS). The data set includes 127,294 TDS results that were collected at 12,339 sites between 1900 and 2022, and 705,918 SC results that were collected at 19,630 sites between 1894 and 2022. The SC results represented 244,784 discrete measurements at 19,625 sites and 461,134 mean daily values from continuous monitoring at 193 sites. The data retrieved from the WQP were harmonized to create a standardized and readily usable dataset. The harmonization process included the synthesis of parameter names and fractions, the reconciliation of remarks and other data qualifiers, the resolution of duplicate records, and basic checks of the data quality. The harmonized results at 230 sites were selected for additional data processing because those sites were potential calibration targets for TDS watershed modeling for the UCRB using the USGS Spatially Referenced Regression on Watershed attributes (SPARROW) model. The 230 sites met the minimum criteria for the number and seasonal distribution of samples, the length of the sampling period, and the amount of overlap with the streamflow record at a nearby gage. The measured TDS concentrations at those sites were supplemented with estimated TDS concentrations that were determined from relations between measured TDS and SC results within the UCRB. A site-specific regression of TDS on SC was used to estimate TDS from SC at 143 sites, while a regional conversion factor between TDS and SC was used to estimate TDS from SC at 87 sites. The final TDS data for the 230 sites included 50,003 measured values from the WQP, 378,147 values estimated using the equation from a site-specific regression of TDS on SC (with 350,840 based on mean daily SC values), and 30,880 values estimated using a regional median ratio between TDS and SC.

This data release contains total dissolved solids (TDS) concentrations and specific conductance (SC) measurements collected at surface-water monitoring locations and groundwater monitoring wells within the Upper Colorado River Basin (UCRB) between 1894 and 2022. Discrete TDS and SC results were obtained from the Water Quality Portal (WQP). Continuous SC monitoring results were obtained from the USGS National Water Information System (NWIS). The data set includes 127,294 TDS results that were collected at 12,339 sites between 1900 and 2022, and 705,918 SC results that were collected at 19,630 sites between 1894 and 2022. The SC results represented 244,784 discrete measurements at 19,625 sites and 461,134 mean daily values from continuous monitoring at 193 sites. The data retrieved from the WQP were harmonized to create a standardized and readily usable dataset. The harmonization process included the synthesis of parameter names and fractions, the reconciliation of remarks and other data qualifiers, the resolution of duplicate records, and basic checks of the data quality. The harmonized results at 230 sites were selected for additional data processing because those sites were potential calibration targets for TDS watershed modeling for the UCRB using the USGS Spatially Referenced Regression on Watershed attributes (SPARROW) model. The 230 sites met the minimum criteria for the number and seasonal distribution of samples, the length of the sampling period, and the amount of overlap with the streamflow record at a nearby gage. The measured TDS concentrations at those sites were supplemented with estimated TDS concentrations that were determined from relations between measured TDS and SC results within the UCRB. A site-specific regression of TDS on SC was used to estimate TDS from SC at 143 sites, while a regional conversion factor between TDS and SC was used to estimate TDS from SC at 87 sites. The final TDS data for the 230 sites included 50,003 measured values from the WQP, 378,147 values estimated using the equation from a site-specific regression of TDS on SC (with 350,840 based on mean daily SC values), and 30,880 values estimated using a regional median ratio between TDS and SC.

Total dissolved solids (TDS) in surface waters affect water quality and useability and are of particular concern in the Colorado River Basin. Estimates of current and past TDS concentration and flux in rivers support appropriate management and salinity control measures. In this study we estimated the total dissolved solid concentration and flux at 11 sites on tributaries of the Colorado River, starting as early as 1938 until 2021. Of these sites, eight were not affected by dams. For these we estimated daily and water year flow normalized TDS concentration and flux using the Weighted Regressions on Time Discharge and Season (WRTDS) water quality modeling framework. For the three sites situated below dams, we used flow-weighted concentrations to estimate water year mean TDS concentrations. Along with these estimates, we include information about the timing of construction, and capacity of dams in the Lower Colorado River Basin.

Total dissolved solids (TDS) in surface waters affect water quality and useability and are of particular concern in the Colorado River Basin. Estimates of current and past TDS concentration and flux in rivers support appropriate management and salinity control measures. In this study we estimated the total dissolved solid concentration and flux at 11 sites on tributaries of the Colorado River, starting as early as 1938 until 2021. Of these sites, eight were not affected by dams. For these we estimated daily and water year flow normalized TDS concentration and flux using the Weighted Regressions on Time Discharge and Season (WRTDS) water quality modeling framework. For the three sites situated below dams, we used flow-weighted concentrations to estimate water year mean TDS concentrations. Along with these estimates, we include information about the timing of construction, and capacity of dams in the Lower Colorado River Basin.

This U.S. Geological Survey (USGS) data release contains stream water chemistry and streamflow data collected in late August and early September, 2021 from 28 sites located throughout Colorado, USA. The sampled streams all drain high-elevation mountain watersheds in areas where the bedrock is hydrothermally altered and contains abundant sulfide minerals. Most sampled streams are therefore affected by natural acid-rock drainage. All sites had been sampled in prior years so that the 2021 data could be used to evaluate potential changes in stream water chemistry in recent decades. Streamflow was also quantified at most sites using data from a sodium chloride slug addition wherein specific conductivity readings were used as a surrogate for the tracer concentration.

This U.S. Geological Survey (USGS) data release contains stream water chemistry and streamflow data collected in late August and early September, 2021 from 28 sites located throughout Colorado, USA. The sampled streams all drain high-elevation mountain watersheds in areas where the bedrock is hydrothermally altered and contains abundant sulfide minerals. Most sampled streams are therefore affected by natural acid-rock drainage. All sites had been sampled in prior years so that the 2021 data could be used to evaluate potential changes in stream water chemistry in recent decades. Streamflow was also quantified at most sites using data from a sodium chloride slug addition wherein specific conductivity readings were used as a surrogate for the tracer concentration.

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.