Patrick M. McCarthy Bryant C. Jurgens Jennifer S. Harkness 20230925 tabular digital data https://doi.org/10.5066/P9KUBQKM Jennifer S. Harkness Patrick M. McCarthy Bryant C. Jurgens Zeno F. Levy 20230921 publication n/a American Chemical Society (ACS) https://doi.org/10.1021/acsestwater.3c00239 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. This data release was compiled for the purpose of modeling and evaluating the contributions of up to 7 different water sources to the major ion geochemistry of USGS and CA-DDW groundwater samples within the Indio subbasin. The analysis was completed as part of a study of salinity trends in groundwater in the Coachella Valley, which includes discussion and interpretation of the included inverse model results. All data are current as of date of publication. 19620226 20211222 See Supplemental Info Complete None planned Coachella Valley -116.7271 -115.8978 33.9246 33.3724 USGS Thesaurus groundwater quality groundwater geochemical processes mathematical simulation hydrogeology water chemistry inverse modeling USGS information products data release USGS Metadata Identifier USGS:63caf1fad34e06fef14f3f97 Geographical Areas Coachella Valley Indio Subbasin Palm Desert La Quinta Common geographic areas Indio California Riverside Palm Springs None. Please see 'Distribution Info' for details. None. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Patrick M Mccarthy U.S. Geological Survey, SOUTHWEST REGION STUDENT TRAINEE (HYDRO) mailing address

6000 J Street Placer Hall

Sacramento CA 95819 US 916-278-3000 pmccarthy@usgs.gov This data release contains two data tables and one data dictionary formatted as a comma-separated text files. Microsoft Excel for Microsoft 365 MSO (32-bit) version 2102 was used for tabular data. J.H. Robison 19810101 publication n/a Office of Scientific and Technical Information (OSTI) https://doi.org/10.2172/5045384 David L. Parkhurst C.A.J. Appelo 2013 publication n/a US Geological Survey https://doi.org/10.3133/tm6A43 P.B. McMahon F.H. Chapelle 200803 publication Ground Water vol. 46, issue 2 n/a Wiley ppg. 259-271 https://doi.org/10.1111/j.1745-6584.2007.00385.x Bryant C. Jurgens Peter B. McMahon Francis H. Chapelle Sandra M. Eberts 2009 publication n/a US Geological Survey https://doi.org/10.3133/ofr20091004 Data are included as reported by publications and public databases. The compiled data were re-censored to remove non-detect values. For all other quality control evaluations, see original data release (Harkness, 2022) as no additional quality control evaluations were performed. No logical tests were performed. Data were not rounded. This data release includes all sites and samples from Harkness (2022) that met the criteria a) samples with data for water quality constituents needed to accurately perform the inverse modeling b) wells with sufficient number of samples to perform a timeseries analysis. For these selected samples, the data release further includes all inverse models that met the model acceptance criteria. Samples and sites that could not be modeled and inverse models that did not pass the acceptance criteria models are not included. A formal accuracy assessment of the horizontal positional information in the data set has not been conducted. A formal accuracy assessment of the vertical positional information in the data set has either not been conducted or is not applicable. Jennifer S Harkness 20220711 tabular digital data Reston, VA US Geological Survey data release https://doi.org/10.5066/P92DU67Q Digital and/or Hardcopy 19330131 20211231 observed Harkness (2022) Source dataset for all analytical sample and endmember major ion geochemistry and TDS, apart from the geothermal well. Project geospatial extent and well location data. Step 1 – Table_Indio_ModelResults.csv construction 1. Digital tabular data from the parent data release (Harkness, 2022) was received in Microsoft Excel file formats. Data were tabularized into common units, formatted for PHREEQC input, and checked for input errors. For many fields, if a description field was present, and indicated the result was below a method detection limit or reporting limit, the converted value was replaced with -999 because inverse modeling does not utilize non-detect values. 2. For samples with missing bicarbonate (HCO3) concentrations, the bicarbonate value was calculated from the reported Alkalinity using the equation: HCO3 = Alkalinity (mg/L) * 61 / 50. Affected samples are indicated by the "Bicarbonate calculated from Alkalinity" flag in the "Well Notes" column of the Table_Indio_Chemistry.csv dataset. 3. The general redox category and predominant redox process for each sample was calculated using the classification scheme of McMahon and Chapelle (2008). An automated worksheet program (Jurgens and others, 2009) was used to assign each general redox category. This classification also includes the calculation of each samples pe and Eh values, which are included in the Table_Indio_Chemistry.csv dataset 4. Samples used for inverse modeling were selected from the master dataset based on the following two criteria: 1) the sample location was within the study area, and 2) the sample contained complete to nearly complete pH, alkalinity, calcium, chloride, magnesium, potassium, sodium, nitrate, silica, and sulfate measurements. 5. The dataset was split into three separate modeling datasets: a calibration dataset, a most recent value dataset, and a timeseries dataset. In some instances, a site or sample may be present in more than one dataset if it fulfilled multiple criteria. This is indicated in the Dataset column in the associated tables. 6. Samples chosen for the calibration dataset were selected based on the following criteria: 1) Samples collected by the USGS in the study area, 2) the sample was the most recent, post-2010 sample for a given well, and 3) the sample contained complete pH, alkalinity, calcium, chloride, magnesium, potassium, sodium, nitrate, silica, and sulfate measurements. 7. To construct the most recent value dataset, the most recent, post-2010 sample for each well was selected from the master dataset. Samples from all reporting agencies and data sources that had sufficient major-ion geochemistry were used for inverse modeling. 8. Samples selected from the master dataset for the timeseries analysis were required to be part of continuous decadal sampling intervals of 1980 through 2000 or 1990 through 2010 and have sufficient major-ion geochemistry to run an inverse model. Harkness (2022) 2022 Step 2 - Model Design 1. Endmember selection is described in the text of the associated publication (Harkness et al, in prep). Endmember samples and chemistry are included in the Table_Indio_Chemistry.csv table and are indicated in the Model Type and Dataset fields. 2. The primary phases considered in the inverse modeling were water (H2O(g)), amorphous silica (SiO2), fertilizer as Calcium Nitrate (Ca(NO3)2), CO2(g), Calcite, Plagioclase, organic matter as CH2O, and ion-exchange reactions involving Ca, Na, K, and Mg. All phases were permitted to dissolve into or precipitate out of solution to simulate naturally occurring geochemical processes. In the case where these conditions did not produce a model solution, halite was added to the phases to account for both evaporation and increased mixing from the more saline endmembers. 3. The uncertainty for all endmembers, elements, and geochemical phases was set to 10% and the tolerance for the optimizing solver set to 1x10-10. The model was constrained to reduce the models to the minimum number of phases that could satisfy all the above constraints within the specified uncertainty limits. The PHREEQC “-minimal” modeling keyword minimizes the number of calculations that would be performed and produces the models that contain the only most essential geochemical reactions (Parkhurst & Appelo, 1999). 4. Constituents not included in the set of geochemical phases were included under the PHREEQC '-balance' keyword to include that element as a mole-balance constraint in inverse modeling. 2022 Step 3 - Dissolved Silica Modeling 1. In both datasets, dissolved silica was the limiting chemical constituent and was unreported in 1992 samples. For these samples, modeled silica concentrations were used in place of measured concentrations. Modeled silica concentrations were computed using a linear regression between pH and silica saturation index of samples with silica and pH. PHREEQC was used to calculate the silica saturation index (SSI) of each sample. The relationship between pH and silica is given as: Y= -0.17 (pH)+0.58; R^2=0.60 2. To verify the accuracy of this modeling approach, the modeled total dissolved solids (TDS) in mg/L was compared against the measured TDS for each sample. This relationship is defined by the linear regression equation: Y=0.96x+82.09; R^2=0.9995 3. The TDS for each sample was recalculated using the modeled silica concentrations in place of the measured, and the regression analysis repeated. The relationship between the modeled TDS and measured TDS following this approach is defined by the linear regression equation: Y=0.96x+84.18; R^2=0.9994. 4. The regression equation Y= -0.17 (pH)+0.58 was then used to calculate the SSI for each sample absent of a measured silica concentration in the master dataset. 5. A basic PHREEQC equilibrium model was run using the calculated SSI for each sample, outputting the dissolved silica concentration at the SSI into a tabular dataset. 2022 Step 4 - Constituent Precision 1. Differences in analytical precision between reported constituents may result in computational rounding errors, preventing samples from being successfully modeled. To account for this, all chemical constituents were first rounded to equal degrees of precision prior to executing the model. Reported results greater than 10 were treated as integers, results greater than 0 and less than 10 were rounded to 1 decimal point, and results less than 1 were rounded to 2 decimal points. Chemistry included in the Table_Indio_Chemistry.csv table of this data release is presented unrounded to preserve the original reported values. 2022 Step 5 - Inverse Modeling 1. The datasets were input into inverse model iteratively following the above conventions. 2. Model input parameters include the calculated sample pe (McMahon and Chapelle, 2008; Jurgens, 2009), sample pH, and major-ion chemistry. Alkalinity was reported as CaCO3 where available or was substituted for Alkalinity as HCO3 if necessary. Additionally, the modeled silica concentrations were used in the models for samples that do not have measured dissolved silica concentrations. For the remaining constituents, if the value was missing or non-detect that constituent was omitted from the solution string. 3. The PHREEQC solution strings for each sample were constructed from the tabular data listed above and passed directly into the modeling software. The models were then run using the Amm.dat database and results output in a tabular data format for interpretation. 2022 Step 6 - Model Evaluation Prior to evaluating and summarizing the model results, additional calculations were performed on the tabular model data to assist with model evaluation and post-processing. 1. The TDS contributed from each mixing endmember was calculated for each model by multiplying the reported TDS of each endmember by the mixing fraction. The reported TDS in mg/L for each endmember can be found in the Table_Indio_Chemistry.csv table. Represented as “_TDS” in the tabular data. 2. The total TDS contributed by the endmembers was calculated as the sum of the TDS contributed by all endmembers. 3. The percent TDS contributed by each endmember to the total TDS was calculated by dividing the contributed TDS by the total TDS. Represented as “_TDS_%” in the tabular data. 4. The percent difference between the modeled total contributed TDS and the reported sample TDS was calculated. Represented as “TDS_percent_difference” in the tabular data. 5. To evaluate the contribution of evaporation or dilution in each model, the sums of the mixing fractions with and without H2O(g) mole transfer were calculated. The “total_mix_frac” column represents the sum of the 7 endmember mixing fractions. The “mass_H2O” column represents the mass of water add to or removed from the water and is calculated by multiplying the molar transfer of H2O(g) by the molar mass of H2O, 0.01802 kg/mol. Similarly, the “mixing_frac_with_H2O” represents the sum of the endmember mixing fractions and the mass added or removed by the H2O(g) phase. This is necessary check to account for for mixing fractions greater than 1, which signal evaporation is also occurring within the model, or models where the mixing fractions do not sum to 1, indicating that water has been derived by mineral reactions in the mole-balance model. However, when the mass of water is accounted for, the mixing fractions should sum to 1. 2023 Step 7 - Post-processing Filters Models that did not accurately represent the geochemistry of the solution were removed from the dataset. This filtering first accounted for models with model errors outside of an acceptable range for the study. This filtering scheme is referred to as "Base Filter" in the associated Table_Indio_Models.csv table and includes the following criteria: 1. Models where the Sum of the Residuals was greater than 30 2. Models with a maximum fractional error greater than 10%. 3. Models that involved sodium mole transfer (NaX) greater than -0.001 4. Models resulting in total TDS contributions less than 0. In some instances, it was found that the above filtering schema was not sufficient to removed nonviable models from the dataset, and additional filtering criteria were applied. These filtering criteria include: 5. Removal of models with a TDS percent difference greater than 25%. Calculated as the percent difference between the contributed TDS and the reported TDS. 6. Removal of models including greater than 30 moles H2O (dilution) and less than -30 moles H2O (evaporation). These additional filters are indicated by "Base + %TDS" to indicate that, in addition to the base filters, filter 5 above as applied, or "Base + H2O+%TDS" to indicate that all 6 filters outlined above were applied to the sample. 2023 Step 8 - Model Aggregation and Creation of Table_Indio_ModelResults.csv Given the size and complexity of the datasets, it was not possible to evaluate the potential solutions for every sample. Instead, all modeled solutions for each sample were aggregated and the median value for each model output parameter was selected as a representative solution for that sample. During this aggregation step we also determined: 1. The “Dominant Endmember”, which is the mixing endmember with the highest median volumetric mixing fraction. 2. The “Dominant Contributor”, which is the endmember that contributed the highest median TDS to each sample. 3. The percent contribution of the Colorado River Water to the total TDS of the sample (CRW%). This value is calculated for each sample as the median volumetric contribution of the Colorado River Water endmember; however, the calculation only considers models with a volumetric mixing fraction greater than 0. As a final filtering step, aggregated samples where the median volumetric contribution of the dominant endmember was less than 10% were removed from the dataset. The samples involved too little contribution from the mixing endmembers, and too great a contribution from mineral phases to appropriately address the study goals and were therefore deemed nonviable. 2023 Vector G-polygon 1 Albers Conical Equal Area 34.0 40.5 -120.0 0.0 0.0 -4000000.0 coordinate pair 0.6096 0.6096 meters North_American_Datum_1983 GRS 1980 6378137.0 298.257222101 Table_Indio_Chemistry.csv Comma Separated Value (CSV) file containing data. Producer Defined Site_Name Non-unique well ID Producer Defined NA Not available Producer defined ID assigned to well in database prioritized as 1) USGS_Project_ID, 2) USGS Station ID, 3) DWR PS-Code, 4) Geotracker ID, 5) PLSS or 6) local name if no other ID available USGS_STATION_ID Unique 15-digit USGS defined identification number Producer Defined NA Not available Producer defined Used to retrieve data from the National Water Information System (NWIS) web: https://waterdata.usgs.gov/nwis? USGS_Project_ID Sample ID assigned by a USGS project Producer Defined NA Not available Producer defined The USGS_Project_ID is an alphanumeric text field that contains letters and sequence numbers and is assigned to sites sampled by a project. Sites with USGS_Project_IDs with the prefix Indio-GW were sampled for this project. Sites with the prefix COA, COAU, or S11-CODA were sampled for California Groundwater Ambient Monitoring and Assessment Program Priority Basin Project study units. PS_CODE Primary Station Code Producer Defined NA Not available Producer defined Primary station code used by DDW as the unique well ID Geotracker_ID Geotracker Facility or Site ID Producer Defined NA Not available Producer defined Unique identifier for the facility or site within the Geotracker Electronic Submittal of Information system; https://geotracker.waterboards.ca.gov/ PLSS Public Land Survey System ID Producer Defined NA No Data Producer defined ID assigned to well based on location within the Township designation, Range designation, and the section number in the Public Land Survey System; https://gis.data.ca.gov/datasets/2b43d73d12664b73943478741dc5dbf4. SampleDate Date sample was collected, Formatted as year-month-date. Producer Defined 1962-02-26 2021-12-22 Dataset Indicates the dataset the sample was used in. Producer Defined Natural groundwater evolution endmember Indicates that the sample was used as the Natural groundwater evolution mixing endmember. Producer defined Salton Sea endmember Indicates that the sample was used as the Salton Sea mixing endmember. Producer defined Geothermal endmember Indicates that the sample was used as the Geothermal mixing endmember. Producer defined Freshwater endmember Indicates that the sample was used as the Freshwater mixing endmember. Producer defined Wastewater effluent endmember Indicates that the sample was used as the Wastewater effluent mixing endmember. Producer defined Colorado River water endmember Indicates that the sample was used as the Colorado River mixing endmember. Producer defined Agricultural runoff endmember Indicates that the sample was used as the Agricultural runoff mixing endmember. Producer defined Timeseries Indicates that the sample and inverse modeling results are part of the timeseries dataset. Producer defined Calibration Indicates that the sample and inverse modeling results are part of the model calibration dataset. Producer defined Most Recent Value Indicates that the sample and inverse modeling results are part of the most recent value dataset. Producer defined Most Recent Value, Calibration Indicates that the sample and inverse modeling results are part of the most recent value and model calibration datasets. Producer defined pe Conventional negative log of the activity of the electron Producer Defined -999 Not calculated Producer defined -3.5 4.0 standard units Eh Electrical conductivity of the solution Producer Defined -999 Not calculated Producer defined -0.2 0.25 volts pH pH measurement, in standard units Producer Defined -999 Unknown Producer defined 6.79 10.7 standard units Ca_mgL Dissolved calcium concentration Producer Defined -999 Unknown Producer defined 1.809 1349.0 mg/L Mg_mgL Dissolved magnesium concentration Producer Defined -999 Unknown Producer defined 0.01 107.1 mg/L Na_mgL Dissolved sodium concentration Producer Defined -999 Unknown Producer defined 8 2891 mg/L K_mgL Dissolved potassium concentration Producer Defined -999 Unknown Producer defined 0.4 32.0 mg/L Alkalinity_mgL Total alkalinity as calcium carbonate concentration Producer Defined -999 Unknown Producer defined 18.5 250.0 mg/L CaCO3 HCO3_mgL Dissolved bicarbonate concentration Producer Defined -999 Unknown Producer defined 29 690 mg/L Cl_mgL Dissolved chloride concentration Producer Defined -999 Unknown Producer defined 1.7 6836.419 mg/L SO4_mgL Dissolved sulfate concentration Producer Defined -999 Unknown Producer defined 10 1570.819 mg/L Si_mgL Dissolved silica concentration Producer Defined -999 Unknown Producer defined 0.06 37.0 mg/L Nitrate_mgL Dissolved nitrate concentration Producer Defined -999 Unknown Producer defined 0.0045 25.0 mg/L N TDS_mgL Total dissolved solids concentration Producer Defined -999 Unknown Producer defined 116 11753.0 mg/L Well Notes Total dissolved solids concentration Producer Defined NA Unknown Producer defined NA Not applicable Producer defined Bicarbonate calculated from Alkalinity Reported bicarbonate concentration (HCO3_mgL) is calculated from the reported Alkalinity. Producer defined Citation Source citation for sample taken from Harkness, 2022. Producer Defined Coachella Valley Water District (2015) 2015 Coachella Valley Water District Salt and Nutrient Management Plan; http://web.cvwd.org/snmp/library/WQData-Share.xlsx Producer defined Coachella Valley Water District (2022) Annual Progress Report on Implementation of the Coachella Valley Salt and Nutrient Management Plan Groundwater Monitoring Workplan Calendar Year 2021 Prepared Producer defined California Department of Water Resources (2021a) California Department of Water Resources Water Data Library; https://wdl.water.ca.gov/ Producer defined National Water Information System (2021) National Water Information System (NWIS) Web accessed December 13, 2021; https://doi.org/10.5066/F7P55KJN Producer defined California State Water Resources Control Board Division of Drinking Water (2021) California State Water Resource Control Board Division of Drinking Water EDT Library, accessed Jan 1, 2022; https://www.waterboards.ca.gov/drinking_water/certlic/drinkingwater/EDTlibrary.html Producer defined California State Water Resources Control Board Geotracker (2021) California State Water Resources Control Board Electronic Deliverable Format accessed 2021; https://geotracker.waterboards.ca.gov/data_download_by_county Producer defined Robison (1981) Robison, J.H., 1981, Data from geothermal wells near Oasis, lower Coachella Valley, California, https://doi.org/10.2172/5045384 Producer defined Table_Indio_ModelResults.csv Comma Separated Value (CSV) file containing data. Producer Defined Site_Name Well ID assigned by Harkness (2022). Producer Defined Prioritized as 1) USGS Project ID, 2) USGS Station ID, 3) DWR PS-Code, 4) Geotracker ID, 5) PLSS or 6) local name if no other ID available unique_sample_id Unique sample ID used to locate the Site_Name and SampleDate combination in the dataset. Producer Defined Unique ID generated by incrementing the samples by Site_Name and SampleDate beginning with 1 for the oldest sample per site. SampleDate Date sample was collected, Formatted as year-month-day Producer Defined 1962-02-26 2021-12-22 Dataset Indicates the dataset the sample was used in. Producer Defined Most Recent Value Indicates that the sample and inverse modeling results are part of the most recent value dataset. Producer defined Timeseries Indicates that the sample and inverse modeling results are part of the timeseries dataset. Producer defined Calibration Indicates that the sample and inverse modeling results are part of the model calibration dataset. Producer defined Most Recent Value, Calibration Indicates that the sample and inverse modeling results are part of the calibration and most recent value datasets. Producer defined FilterMethod Indicates which filtering scheme was applied to the model results prior to aggregation. See process steps Producer Defined NA Not Available Producer defined Base Filter Indicates that filtering applied to the samples individual models included consideration of the sum of the residuals, the maximum fractional error, sodium exchange, and TDS contribution. See process steps Producer defined Base + %TDS Indicates that filtering applied to the samples individual models included consideration of the sum of the residuals, the maximum fractional error, sodium exchange, TDS contribution and % TDS difference. See process steps Producer defined Base + H2O+%TDS Indicates that filtering applied to the samples individual models included consideration of the sum of the residuals, the maximum fractional error, sodium exchange, TDS contribution,% TDS difference, and H2O mole transfer. See process steps Producer defined RedoxCat Indicates the general redox category as defined by McMahon and Chapelle (2008) and Jurgens (2009). Producer Defined Indeterminate Insufficient geochemistry to make a redox determination. Citation AnoxicOrMixed(oxic-anoxic) See original publication for definition Citation OxicOrAnoxic See original publication for definition Citation Mixed(anoxic)Or(oxic-anoxic) See original publication for definition Citation OxicOrSuboxic See original publication for definition Citation O2 >= 0.5 mg/L See original publication for definition Citation Oxic See original publication for definition Citation Anoxic See original publication for definition Citation Suboxic See original publication for definition Citation RedoxProcess Indicates the predominant redox process as defined by McMahon and Chapelle (2008) and Jurgens (2009). Producer Defined Indeterminate Insufficient geochemistry to make a redox determination. Producer defined Fe(III)/SO4-O2? See original publication for definition Citation O2?OrNO3 See original publication for definition Citation Fe(III)/SO4-O2?OrNO3 See original publication for definition Citation O2?OrSuboxic See original publication for definition Citation Unknown See original publication for definition Citation O2 See original publication for definition Citation Mn(IV)-O2?OrNO3 See original publication for definition Citation Mn(IV) See original publication for definition Citation NO3 See original publication for definition Citation Suboxic See original publication for definition Citation Fe(III)/SO4 See original publication for definition Citation H2O(g) Median millimole contribution Median mole transfer of denoted phase; positive value indicates dilution; negative value indicates evaporation. Producer Defined -999 No modeled data Producer defined -685480 54246 mmol SiO2(a) Median millimole contribution Median mole transfer of denoted phase; positive value indicates dissolution, negative value indicates exsolution. Producer Defined -999 No modeled data Producer defined -2.9969 0.4271 mmol KX Median millimole contribution Median mole transfer of denoted phase; positive value indicates dissolution, negative value indicates exsolution. Producer Defined -999 No modeled data Producer defined -0.829 0.7605 mmol MgX2 Median millimole contribution Median mole transfer of denoted phase; positive value indicates dissolution, negative value indicates exsolution. Producer Defined -999 No modeled data Producer defined -5.6114 2.4441 mmol CaX2 Median millimole contribution Median mole transfer of denoted phase; positive value indicates dissolution, negative value indicates exsolution. Producer Defined -999 No modeled data Producer defined -4.9106 27.26 mmol NaX Median millimole contribution Median mole transfer of denoted phase; positive value indicates dissolution, negative value indicates exsolution. Producer Defined -999 No modeled data Producer defined -59.571 11.26 mmol Calcite Median millimole contribution Median mole transfer of denoted phase; positive value indicates dissolution, negative value indicates exsolution. Producer Defined -999 No modeled data Producer defined -19.08 3.3063 mmol Halite Median millimole contribution Median mole transfer of denoted phase; positive value indicates dissolution, negative value indicates exsolution. Producer Defined -999 No modeled data Producer defined -2.8397 50.227 mmol CH2O Median millimole contribution Median mole transfer of denoted phase; positive value indicates dissolution, negative value indicates exsolution. Producer Defined -999 No modeled data Producer defined 0 0 mmol Calcium_Nitrate Median millimole contribution Median mole transfer of denoted phase; positive value indicates dissolution, negative value indicates exsolution. Producer Defined -999 No modeled data Producer defined -0.0646 0.1955 mmol CO2(g) Median millimole contribution Median mole transfer of denoted phase; positive value indicates dissolution, negative value indicates exsolution. Producer Defined -999 No modeled data Producer defined -18.097 4.5606 mmol Plagioclase Median millimole contribution Median mole transfer of denoted phase; positive value indicates dissolution, negative value indicates exsolution. Producer Defined -999 No modeled data Producer defined 0 0 mmol natural_evolution_median_TDS Median TDS contributed by the Natural Evolution endmember. See process steps Producer Defined -999 No modeled data Producer defined 0.0027 312.984 mg/L colorado_river_water_median_TDS Median TDS contributed by the Colorado River endmember. See process steps Producer Defined -999 No modeled data Producer defined 3.1059 2509.819 mg/L salton_sea_median_TDS Median TDS contributed by the Salton Sea endmember. See process steps Producer Defined -999 No modeled data Producer defined 0.0819 8780 mg/L freshwater_median_TDS Median TDS contributed by the Freshwater endmember. See process steps Producer Defined -999 No modeled data Producer defined 0.2363 616.9223 mg/L geothermal_median_TDS Median TDS contributed by the Geothermal endmember. See process steps Producer Defined -999 No modeled data Producer defined 1.6232 616.9223 mg/L wastewater_median_TDS Median TDS contributed by the Wastewater Effluent endmember. See process steps Producer Defined -999 No modeled data Producer defined 0 656.312 mg/L ag_runoff_median_TDS Median TDS contributed by the Agricultural Runoff endmember. See process steps Producer Defined -999 No modeled data Producer defined 3.7227 2467.71 mg/L Tot_TDS_Cont Median Total TDS contributed by endmember mixing. See process steps Producer Defined -999 No modeled data Producer defined 70.7648 8780 mg/L natural_evolution_TDS_% Median TDS contributed by the Natural Evolution endmember, %. See process steps Producer Defined -999 No modeled data Producer defined 0.0011 84.9645 percent colorado_river_water_TDS_% Median TDS contributed by the Colorado River endmember, %. See process steps Producer Defined -999 No modeled data Producer defined 0.8713 100 percent salton_sea_TDS_% Median TDS contributed by the Salton Sea endmember, %. See process steps Producer Defined -999 No modeled data Producer defined 0.0471 100 percent freshwater_TDS_% Median TDS contributed by the Freshwater endmember, %. See process steps Producer Defined -999 No modeled data Producer defined 0.1271 100 percent geothermal_TDS_% Median TDS contributed by the Geothermal endmember, %. See process steps Producer Defined -999 No modeled data Producer defined 0.6731 66.9193 percent wastewater_TDS_% Median TDS contributed by the Wastewater endmember, %. See process steps Producer Defined -999 No modeled data Producer defined 0 97.1272 percent ag_runoff_TDS_% Median TDS contributed by the Agricultural Runoff endmember, %. See process steps Producer Defined -999 No modeled data Producer defined 0.8355 95.6312 percent TDS_percent_difference Percent difference between median contributed TDS and reported sample TDS Producer Defined -999 No modeled data Producer defined 0.0161 114.4228 percent mass_H2O Median mass of water added to or removed from the model, kg. See process steps Producer Defined -999 No modeled data Producer defined -12.3523 0.9775 kg mixing_frac_with_H2O Sum of the endmember mixing fractions and the mass of water contributed to the model. Producer Defined -999 No modeled data Producer defined 0.9972 1.0002 fraction percent_mass_H2O Sum of the endmember mixing fractions and the mass of water contributed to the model. Producer Defined -999 No modeled data Producer defined -17.2497 42.9714 percent si_SiO2(a) Modeled silica saturation index (Parkhurst and Appelo, 2013) Producer Defined -999 No modeled data Producer defined -1.239 -0.5743 log 10 of the ion activity product divided by equilibrium constant Si_modeled Modeled dissolved silica concentration. See process steps Producer Defined -999 No modeled data Producer defined 14 31 mg/L median_sum_resid Median sum of the residuals of each modeled phase Producer Defined -999 No modeled data Producer defined 0.1986 17.2225 sum median_sum_Delta/U Median sum of each residual divided by its uncertainty limit. Producer Defined -999 No modeled data Producer defined 1.2883 25.323 delta median_MaxFracErr Median maximum fractional error. Producer Defined -999 No modeled data Producer defined 0.0116 0.1 fraction median_nat_evolution_mix_frac Median mixing fraction of the natural groundwater evolution endmember. Producer Defined -999 No modeled data Producer defined 0 1.3973 fraction median_colorado_river_mix_frac Median mixing fraction of the Colorado River endmember. Producer Defined -999 No modeled data Producer defined 0.0046 3.7182 fraction median_salton_sea_mix_frac Median mixing fraction of the Salton Sea endmember. Producer Defined -999 No modeled data Producer defined 0 1 fraction median_freshwater_mix_frac Median mixing fraction of the Freshwater endmember. Producer Defined -999 No modeled data Producer defined 0.0012 13.073 fraction median_geothermal_mix_frac Median mixing fraction of the geothermal endmember. Producer Defined -999 No modeled data Producer defined 0.0011 0.4197 fraction median_wwtp_mix_frac Median Mixing fraction of the wastewater treatment plant endmember. Producer Defined -999 No modeled data Producer defined 0 0.8204 fraction median_ag_mix_frac Median mixing fraction of the agricultural runoff endmember. Producer Defined -999 No modeled data Producer defined 0.0018 1.1751 fraction DominantEndmember Dominant mixing endmember by volume, defined as the endmember with the highest median volumetric mixing fraction. See process steps Producer Defined Freshwater Indicated endmember is the dominant contributing endmember to final solution chemistry Producer defined Colorado River Water Indicated endmember is the dominant contributing endmember to final solution chemistry Producer defined Geothermal Indicated endmember is the dominant contributing endmember to final solution chemistry Producer defined Wastewater Indicated endmember is the dominant contributing endmember to final solution chemistry Producer defined Ag Runoff Indicated endmember is the dominant contributing endmember to final solution chemistry Producer defined Natural Groundwater Evolution Indicated endmember is the dominant contributing endmember to final solution chemistry Producer defined DominantEndmember_MoleFraction Median mole fraction of the dominant endmember. See process steps Producer Defined -999 No modeled data Producer defined 0.1138 13.073 fraction DominantContributor Dominant endmember by contributed TDS, defined as the endmember with the highest median TDS contributed. See process steps Producer Defined Freshwater Indicated endmember contributes the highest median TDS to the final solution Producer defined Colorado River Water Indicated endmember contributes the highest median TDS to the final solution Producer defined Geothermal Indicated endmember contributes the highest median TDS to the final solution Producer defined Wastewater Indicated endmember contributes the highest median TDS to the final solution Producer defined Ag Runoff Indicated endmember contributes the highest median TDS to the final solution Producer defined Natural Groundwater Evolution Indicated endmember contributes the highest median TDS to the final solution Producer defined DominantContributor_TDSContribution Median percent TDS of the dominant contributing endmember. See process steps Producer Defined -999 No modeled data Producer defined 0.6892 100 percent CRW% Median modeled percent Colorado River Water, calculated from all models in which the volumetric contribution of the Colorado River is greater than 0. Producer Defined -999 No modeled data Producer defined 0.0002 1 percent Table_Indio_DataDictionary Comma Separated Value (CSV) file containing data. Producer Defined Table Indicates in which table each Field is found Producer Defined All Field is included in all tables. Producer defined Chemistry Field is included in the Table_Indio_Chemistry.csv table Producer defined Models Field is included in the Models table Producer defined Field Indicates the column header the data dictionary is describing Producer Defined Column header of the Table_Indio_Models.csv and Table_Indio_Chemistry.csv tabular datasets. Description Text description defining the data field. Producer Defined Text description defining the data field. Missing Value Indicator Indicates the placeholder value used in the field when no data is recorded Producer Defined NA No Data Producer defined -999 -999 Missing Value Definition Defines the missing value indicator Producer Defined Not Available Data was not available or not reported Producer defined No modeled results Model did not produce results for indicated field Producer defined min Minimum value recorded in indicated field Producer Defined NA/-999 No Data or No modeled results Producer defined Minimum value recorded in indicated field median Median value recorded in indicated field Producer Defined NA/-999 No Data Producer defined No Data or No modeled results max Maximum value recorded in indicated field Producer Defined NA/-999 No Data or No modeled results Producer defined Maximum value recorded in indicated field units Indicates the units the associated field is reported in Producer Defined NA Not Applicable Producer defined fraction Data is reported as a fraction Producer defined millimole Data is reported in moles Producer defined percent Data is reported as a percent Producer defined log 10 of the ion activity product divided by equilibrium constant Data is reported as log 10 of the ion activity product divided by equilibrium constant Producer defined mg/L Data is reported in mg/L Producer defined sum Data is reported as a sum Producer defined delta Data is reported as a difference between two values Producer defined standard units Data is reported in the standard unit of measure for the indicated field Producer defined volts the unit of electric potential Producer defined Associated Header Provides the corresponding dataset header from Harkness (2022) for fields that are sourced from the data set. Producer Defined NA Data is not contained in source data release Producer defined Site_Name Data is from the Site_Name field Producer defined USGS_STATION_ID Data is from the USGS_STATION_ID field Producer defined PS_CODE Data is from the PS_CODE field Producer defined Geotracker_ID Data is from the Geotracker_ID field Producer defined PLSS Data is from the PLSS field Producer defined SampleDate Data is from the SampleDate field Producer defined Calcium Data is from the Calcium field Producer defined Magnesium Data is from the Magnesium field Producer defined Sodium the unit of electric potential Producer defined Potassium Data is from the Potassium field Producer defined Alkalinity Data is from the Alkalinity field Producer defined Bicarbonate Data is from the Bicarbonate field Producer defined Chloride Data is from the Chloride field Producer defined Sulfate Data is from the Sulfate field Producer defined Nitrate Data is from the Nitrate field Producer defined TDS Data is from the TDS field Producer defined Data are compiled into two comma separated files (.csv), 'Table_Indio_Chemistry.csv" and "Table_Indio_Models.csv" which contain the sample chemistry data and model results respectively. The entity and attribute information provided here describes the tabular data associated with the datasets. Please review the detailed descriptions that are provided (the individual attribute descriptions) for information on the values that appear as fields/table entries of the dataset. McCarthy, P.M., Jurgens, B.C., Harkness, J.S., 2023, Inverse Model Data for: Salinity trends in a groundwater system supplemented by 50 years of managed aquifer recharge: U.S. Geological Survey data release, https://doi.org/10.5066/P9KUBQKM. U.S. Geological Survey GS ScienceBase mailing address

Denver Federal Center, Building 810, Mail Stop 302

Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data for other purposes, nor on all computer systems, nor shall the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/P9KUBQKM None 20230925 Patrick M Mccarthy U.S. Geological Survey, SOUTHWEST REGION STUDENT TRAINEE (HYDRO) mailing address

6000 J Street Placer Hall

Sacramento CA 95819 US 916-278-3000 pmccarthy@usgs.gov FGDC Biological Data Profile of the Content Standard for Digital Geospatial Metadata FGDC-STD-001.1-1999