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 data release contains measured stream discharge and total dissolved solids (TDS) data and estimated values for daily stream TDS loads, daily baseflow discharge, and daily baseflow TDS loads for 205 locations in the Upper Colorado River Basin. The estimated values, which represent conditions between 10/1/1985 and 9/30/2020, were obtained using the Weighted Regressions on Time, Discharge, and Season (WRTDS) program and a previously published method for hydrograph separation.

This data release contains measured stream discharge and total dissolved solids (TDS) data and estimated values for daily stream TDS loads, daily baseflow discharge, and daily baseflow TDS loads for 205 locations in the Upper Colorado River Basin. The estimated values, which represent conditions between 10/1/1985 and 9/30/2020, were obtained using the Weighted Regressions on Time, Discharge, and Season (WRTDS) program and a previously published method for hydrograph separation.

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

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

This data release contains the input and output used to assess the potential effect of climate on streamflow and salinity (measured as total dissolved solids [TDS]) yields across the Upper Colorado River Basin from water years 1986 to 2021. This analysis included estimation of the spatiotemporal variability in mean annual climatic variables (air temperature, snow water equivalent, precipitation and antecedent precipitation), mean annual streamflow yields, and mean annual TDS yields at 34 sites within the basin. Generalized Additive Models (GAMs) were used to look at non-linear trends in streamflow and TDS yields in the Upper Colorado River Basin. GAMs were also used to create attribution models that explain temporal variability in streamflow and TDS using climate variables (precipitation, snow, and air temperature). A detailed description of the analysis is provided in the associated journal article.

This data release contains six different datasets that were used in the report SIR 2018-5108. These datasets contain discharge data, discrete dissolved-solids data, quality-control discrete dissolved data, and computed mean dissolved solids data that were collected at various locations between the Hoover Dam and the Imperial Dam. Study Sites: Site 1: Colorado River below Hoover Dam Site 2: Bill Williams River near Parker Site 3: Colorado River below Parker Dam Site 4: CRIR Main Canal Site 5: Palo Verde Canal Site 6: Colorado River at Palo Verde Dam Site 7: CRIR Lower Main Drain Site 8: CRIR Upper Levee Drain Site 9: PVID Outfall Drain Site 10: Colorado River above Imperial Dam Discrete Dissolved-solids Dataset and Replicate Samples for Discrete Dissolved-solids Dataset: The Bureau of Reclamation collected discrete water-quality samples for the parameter of dissolved-solids (sum of constituents). Dissolved-solids, measured in milligrams per liter, are the sum of the following constituents: bicarbonate, calcium, carbonate, chloride, fluoride, magnesium, nitrate, potassium, silicon dioxide, sodium, and sulfate. These samples were collected on a monthly to bimonthly basis at various time periods between 1990 and 2016 at Sites 1-5 and Sites 7-10. No data were collected for Site 6: Colorado River at Palo Verde Dam. The Bureau of Reclamation and the USGS collected discrete quality-control replicate samples for the parameter of dissolved-solids, sum of constituents measured in milligrams per liter. The USGS collected discrete quality-control replicate samples in 2002 and 2003 and the Bureau of Reclamation collected discrete quality-control replicate samples in 2016 and 2017. Listed below are the sites where these samples were collected at and which agency collected the samples. Site 3: Colorado River below Parker Dam: USGS and Reclamation Site 4: CRIR Main Canal: Reclamation Site 5: Palo Verde Canal: Reclamation Site 7: CRIR Lower Main Drain: Reclamation Site 8: CRIR Upper Levee Drain: Reclamation Site 9: PVID Outfall Drain: Reclamation Site 10: Colorado River above Imperial Dam: USGS and Reclamation Monthly Mean Datasets and Mean Monthly Datasets: Monthly mean discharge data (cfs), flow weighted monthly mean dissolved-solids concentrations (mg/L) data and monthly mean dissolved-solids load data from 1990 to 2016 were computed using raw data from the USGS and the Bureau of Reclamation. This data were computed for all 10 sites. Flow weighted monthly mean dissolved-solids concentration and monthly mean dissolved-solids load were not computed for Site 2: Bill Williams River near Parker. The monthly mean datasets that were calculated for each month for the period between 1990 and 2016 were used to compute the mean monthly discharge and the mean monthly dissolved-solids load for each of the 12 months within a year. Each monthly mean was weighted by how many days were in the month and then averaged for each of the twelve months. This was computed for all 10 sites except mean monthly dissolved-solids load were not computed at Site 2: Bill Williams River near Parker. Site 8a: Colorado River between Parker and Palo Verde Valleys was computed by summing the data from sites 6, 7 and 8. Bill Williams Daily Mean Discharge, Instantaneous Dissolved-solids Concentration, and Daily Means Dissolved-solids Load Dataset: Daily mean discharge (cfs), instantaneous solids concentration (mg/L), and daily mean dissolved solids load were calculated using raw data collected by the USGS and the Bureau of Reclamation. This data were calculated for Site 2: Bill Williams River near Parker for the period of January 1990 to February 2016. Palo Verde Irrigation District Outfall Drain Mean Daily Discharge Dataset: The Bureau of Reclamation collected mean daily discharge data for the period of 01/01/2005 to 09/30/2016 at the Palo Verde Irrigation District (PVID) outfall drain using a stage-discharge relationship.

This data release contains six different datasets that were used in the report SIR 2018-5108. These datasets contain discharge data, discrete dissolved-solids data, quality-control discrete dissolved data, and computed mean dissolved solids data that were collected at various locations between the Hoover Dam and the Imperial Dam. Study Sites: Site 1: Colorado River below Hoover Dam Site 2: Bill Williams River near Parker Site 3: Colorado River below Parker Dam Site 4: CRIR Main Canal Site 5: Palo Verde Canal Site 6: Colorado River at Palo Verde Dam Site 7: CRIR Lower Main Drain Site 8: CRIR Upper Levee Drain Site 9: PVID Outfall Drain Site 10: Colorado River above Imperial Dam Discrete Dissolved-solids Dataset and Replicate Samples for Discrete Dissolved-solids Dataset: The Bureau of Reclamation collected discrete water-quality samples for the parameter of dissolved-solids (sum of constituents). Dissolved-solids, measured in milligrams per liter, are the sum of the following constituents: bicarbonate, calcium, carbonate, chloride, fluoride, magnesium, nitrate, potassium, silicon dioxide, sodium, and sulfate. These samples were collected on a monthly to bimonthly basis at various time periods between 1990 and 2016 at Sites 1-5 and Sites 7-10. No data were collected for Site 6: Colorado River at Palo Verde Dam. The Bureau of Reclamation and the USGS collected discrete quality-control replicate samples for the parameter of dissolved-solids, sum of constituents measured in milligrams per liter. The USGS collected discrete quality-control replicate samples in 2002 and 2003 and the Bureau of Reclamation collected discrete quality-control replicate samples in 2016 and 2017. Listed below are the sites where these samples were collected at and which agency collected the samples. Site 3: Colorado River below Parker Dam: USGS and Reclamation Site 4: CRIR Main Canal: Reclamation Site 5: Palo Verde Canal: Reclamation Site 7: CRIR Lower Main Drain: Reclamation Site 8: CRIR Upper Levee Drain: Reclamation Site 9: PVID Outfall Drain: Reclamation Site 10: Colorado River above Imperial Dam: USGS and Reclamation Monthly Mean Datasets and Mean Monthly Datasets: Monthly mean discharge data (cfs), flow weighted monthly mean dissolved-solids concentrations (mg/L) data and monthly mean dissolved-solids load data from 1990 to 2016 were computed using raw data from the USGS and the Bureau of Reclamation. This data were computed for all 10 sites. Flow weighted monthly mean dissolved-solids concentration and monthly mean dissolved-solids load were not computed for Site 2: Bill Williams River near Parker. The monthly mean datasets that were calculated for each month for the period between 1990 and 2016 were used to compute the mean monthly discharge and the mean monthly dissolved-solids load for each of the 12 months within a year. Each monthly mean was weighted by how many days were in the month and then averaged for each of the twelve months. This was computed for all 10 sites except mean monthly dissolved-solids load were not computed at Site 2: Bill Williams River near Parker. Site 8a: Colorado River between Parker and Palo Verde Valleys was computed by summing the data from sites 6, 7 and 8. Bill Williams Daily Mean Discharge, Instantaneous Dissolved-solids Concentration, and Daily Means Dissolved-solids Load Dataset: Daily mean discharge (cfs), instantaneous solids concentration (mg/L), and daily mean dissolved solids load were calculated using raw data collected by the USGS and the Bureau of Reclamation. This data were calculated for Site 2: Bill Williams River near Parker for the period of January 1990 to February 2016. Palo Verde Irrigation District Outfall Drain Mean Daily Discharge Dataset: The Bureau of Reclamation collected mean daily discharge data for the period of 01/01/2005 to 09/30/2016 at the Palo Verde Irrigation District (PVID) outfall drain using a stage-discharge relationship.

Weighted Regression on Time, Discharge and Season (WRTDS) and WRTDS with Kalman filtering (WRTDS_K) models were developed for total and dissolved cadmium, zinc and lead; total phosphorus and nitrogen; and dissolved orthophosphate at twelve sites in the Spokane River watershed, northern Idaho, for water years 1990 to 2018. The data table contains the annual mean concentrations and annual total loads estimated by WRTDS_K, and the flow-normalized annual mean concentrations and flow-normalized annual total loads estimated by WRTDS for each modeled site and constituent.

Weighted Regression on Time, Discharge and Season (WRTDS) and WRTDS with Kalman filtering (WRTDS_K) models were developed for total and dissolved cadmium, zinc and lead; total phosphorus and nitrogen; and dissolved orthophosphate at twelve sites in the Spokane River watershed, northern Idaho, for water years 1990 to 2018. The data table contains the annual mean concentrations and annual total loads estimated by WRTDS_K, and the flow-normalized annual mean concentrations and flow-normalized annual total loads estimated by WRTDS for each modeled site and constituent.