R. Blaine McCleskey Robert L. Runkel Sheila F. Murphy David A. Roth Ronald C. Antweiler 20240408 tabular digital data Boulder, CO U.S. Geological Survey https://doi.org/10.5066/P14EVYYX R. Blaine McCleskey Robert L. Runkel Sheila F. Murphy David A. Roth 20250110 publication Water Resources Research vol. 61, issue 1 n/a American Geophysical Union (AGU) https://doi.org/10.1029/2024WR037771 Slug additions are often the most accurate method for determining discharge when traditional current meter or acoustic measurements are unreliable because of high turbulence, rocky streambed, shallow or sheet flow, or the stream is physically inaccessible (e.g., under ice or canyon walls) or unsafe to wade (Zellweger et al., 1989, Kilpatrick and Cobb 1984, Ferranti 2015). The slug addition method for determining discharge requires an injection of a known amount of a single salt and high-frequency downstream measurement of solute concentration to capture the response curve (Kilpatrick and Cobb 1984). A new slug method was developed to determine stream discharge utilizing specific conductance and ionic molal conductivities to quantify the downstream salt concentration. The new method adopts an approach that accurately calculates the specific conductance of natural waters (McCleskey, et al., 2012). The main advantage of the new method is high-frequency measurements of specific conductance are easily obtained and the method does not require collection or analyses of discrete samples, allowing for more rapid and less expensive measurements. Data from twenty-nine slug additions are presented. The data were used to evaluate the performance of the new discharge method by comparing with discharge estimates obtained by other means (Manning et al. 2022; McCleskey et al., 2021; U.S. Geological Survey, 2022). File information: SlugAdditions.csv is a tab separated file containing details of each slug addition including stream location, date and time, type and mass of salt added, and discharge determined by an alternative method are presented. SlugAdditions_SC.csv is a tab separated file containing high-frequency specific conductance data collected from twenty-nine slug addition tests. FourmileWQ.csv is a tab separated file containing water quality data from eight different slug addition tests in Fourmile Creek, CO. Specific conductance was calculated and compared to field measurements to demonstrate the validity of the approach. Discharge.xlsx is an Excel spreadsheet that calculates discharge using high-frequency specific conductance data collected downstream from a slug addition. SaltMass.xlsx is an Excel spreadsheet that calculates the salt mass used in the slug addition. References Cited Ferranti, F., 2015. Validation Of Salt Dilution Method For Discharge Measurements In The Upper Valley Of Aniene River (Central Italy). Recent Advances in Environment, Ecosystems and Development. Kilpatrick, F.A. and Cobb, E.D., 1984. Measurement of discharge using tracers. U. S. Geological Survey Open-File Report 84-136. McCleskey, R.B., Nordstrom, D.K., Ryan, J.N. and Ball, J.W., 2012. A new method of calculating electrical conductivity with applications to natural waters. Geochimica et Cosmochimica Acta, 77(0): 369-382. McCleskey, R.B., Antweiler, R.C., Andrews, E.D., Roth, D.A. and Runkel, R.L., 2021. Streamflow and water chemistry in the Tenaya Lake Basin, Yosemite National Park, California. U.S. Geological Survey data release, https://doi.org/10.5066/P9X3WI80. U.S. Geological Survey, 2022. USGS water data for the Nation: U.S. Geological Survey National Water Information System database. accessed July 28, 2022, at https://doi.org/10.5066/F7P55KJN. Zellweger, G.W., Avanzino, R.J. and Bencala, K.E., 1989. Comparison of tracer-dilution and current-meter discharge measurements in a small gravel-bed stream, Little Lost Man Creek, California. U.S. Geological Survey Water-Resources Investigations Report 89-4150. The purpose of this data release is to present high-frequency specific conductance data collected during twenty-nine slug additions. These data are used to evaluate a new method to determine discharge. Details of each slug addition including stream location, date and time, type and mass of salt added, and discharge determined by an alternative method are presented (Manning et al. 2022; McCleskey et al., 2021; U.S. Geological Survey, 2022). 20180619 20210810 publication date Complete None planned -119.8114 -104.6777 40.3800 37.3483 USGS Thesaurus specific conductance conductivity discharge slug USGS Metadata Identifier USGS:6592f65ed34e3265ab14f326 NA NA none none R. Blaine McCleskey U.S. Geological Survey Research Chemist mailing address

3215 Marine St

Boulder CO 80303 US 303-541-3015 303-541-3084 rbmccles@usgs.gov Excel was used to compile all data Quality Assurance and Quality Control Several techniques were used to assure the quality of the ionic analytical data. These techniques included calculation of charge balance, specific conductance imbalance (McCleskey et al., 2012; McCleskey, 2018), analysis of lab blanks, and analysis of U.S. Geological Survey Standard Reference Water Samples. The charge balance calculation is a common quality-assurance/quality-control procedure to check the accuracy of a water analysis (Nordstrom and Munoz, 1994). For samples that were analyzed for major cations and anions, the accuracy of the analyses was checked for charge balance using the geochemical code PHREEQCI (Parkhurst and Appelo, 1999). The mean charge balance was -0.6 percent with a standard deviation of 1.0 percent. Calculated specific conductance also provides a check on field measured specific conductance. The mean specific conductance imbalance was 0.6 percent with a standard deviation of 0.6 percent. Several standard reference water samples were analyzed as unknowns multiple times during each analytical run to check for accuracy. U.S. Geological Survey standard reference water samples (SRWS) were used to check the analytical methods for major and trace metals, anions, and alkalinity (U.S. Geological Survey, 2022). References McCleskey, R.B., 2018, Calculated specific conductance using PHREEQCI: U.S. Geological Survey software release, https://doi.org/10.5066/F7M907VD. McCleskey, R.B., Nordstrom, D.K., Ryan, J.N., and Ball, J.W., 2012, A new method of calculating electrical conductivity with applications to natural waters: Geochimica et Cosmochimica Acta, v. 77, no. 0, p. 369-382. Nordstrom, D.K., and Munoz, J.L., 1994, Geochemical Thermodynamics, 2nd edition (second edition ed.): Caldwell, New Jersey, Blackwell Scientific Publications, 493 p. Parkhurst, D.L., and Appelo, C.A.J., 1999, User's guide to PHREEQC (Version 2) - A computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations: U.S. Geological Survey Water-Resources Investigations Report 99-4259, 312 p. U.S. Geological Survey, 2022, Standard Reference Sample Project: U.S. Geological Survey accessed June 3, 2022 at http://bqs.usgs.gov/srs/. Logical consistency was verified based on specific conductance imbalance, charge balance, and comparison of various specific conductance standards. Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. No formal positional accuracy tests were conducted No formal positional accuracy tests were conducted Salt Additions Twenty-nine slug additions were performed to determine stream discharge. The slug additions were performed in North Quartz and Fourmile Creeks, Colorado and in Cathedral and Tenaya Creeks, Yosemite National Park, California. Sodium chloride was used in twenty-five slug additions and one addition was performed with each of the following salts: sodium bromide, potassium chloride, potassium bromide, and lithium chloride. Unless noted, all salts utilized in the slug additions were reagent grade. We also tested the relatively inexpensive and readily available table salt (Morton). An assay of the table salt showed that it was >99% sodium chloride. Concentrated salt solutions, rather than solid salts, were added to the stream during tracer studies. The slug addition solutions were prepared on-site using a pre-weighed salt, stream water, and a large mixing container (e.g., 20-L bucket). Prior to a site visit, we gravimetrically measured the mass of dried salt (dried at 50°C for 24-hours) and stored it in HDPE bottles. Specific conductance measurements We adhered to the U.S. Geological Survey’s guidance on specific conductance calibration, measurement, and equipment (U.S. Geological Survey, 2019). The specific conductance meters or sondes with specific conductance probe utilized in this study have the capability to measure and log data every 2 to 4 seconds (Thermo Scientific Orion A325, In-Situ Aqua TROLL 500, Yellow Springs Instruments 600 OMS). All specific conductance measurements are reported at 25 degrees Celsius (°C). Prior to salt addition to a stream, a specific conductance meter was programmed to measure and log data. The meter was then installed near the center of the streamflow about 100 to 400 meters downstream from the location of the slug addition allowing for measurement of background specific conductance. The salt slug was added to the stream. The specific conductance was continually monitored and once the specific conductance peak passed and the specific conductance returned to background, the meter was removed from the stream and the logging stopped. The data file of the specific conductance log was then created. Water sample collection and analyses For the eight Fourmile Creek slug additions, discrete water samples were also collected near the SC peak at the downstream monitoring site. In addition, a discrete water sample was collected prior to any slug addition to determine background chemistry. A 1-L grab sample was rapidly collected near each SC peak which was then syringe filtered (0.45 µm) within 24-h. Filtered cation (acidified with 1% v/v HNO3) and anion (no preservative added) splits were then collected from the 1-L grab sample. Laboratory Methods All laboratory measurements were made at U.S. Geological Survey Laboratories. All reagents were of equal or higher purity than the reagent-grade standards of the American Chemical Society. Deionized water and redistilled or trace-metal-grade acids were used in all preparations. Samples were diluted as necessary to bring the analyte concentration within the optimal range of the method. The detection limits for anions were determined using the U.S. Environmental Protection Agency method detection limit (U.S. Environmental Protection Agency, 2016). The detection limits for inductively coupled plasma– optical emission spectroscopy (ICP–OES) were determined using the method presented by Skogerboe and Grant (1970). Details on the instrumentation, techniques, general conditions, and variants from standard procedures are discussed in following sections. Major Cation and Trace Metal Determinations Concentrations of dissolved major cations (Ca, Mg, Na, and K), silica (SiO2), and selected trace elements (As, Al, B, Ba, Be, Cd, Co, Cr, Cu, Fe, Li, Mn, Sr, and Zn) were determined using ICP–OES following the method describe by Roth et al., 2022. The axial plasma viewing orientation was used for the major cations and trace metals, except for potassium. The radial plasma viewing orientation was used for potassium. A cesium chloride ionization buffer was added in-line prior to sample nebulization to suppress the ionization of potassium and lithium in the plasma. Anion and Alkalinity Determinations Concentrations of bromide (Br), chloride (Cl), fluoride (F), nitrate (NO3), and sulfate (SO4) were determined by ion chromatography (IC) with suppressed electrical conductivity detection (Brinton and others, 1995). Analytical errors for these constituents are typically less than 5 percent. Alkalinity was determined by automated titration (Thermo, 940-960 autotitrator) using standardized sulfuric acid (Barringer and Johnsson, 1996; Fishman and Friedman, 1989). Fifteen milliliters of sample were titrated with 0.01 normal (equivalents per liter) sulfuric acid to the bicarbonate end-point. The analytical error in alkalinity concentrations is less than 3 percent. References Cited Barringer, J.L., and Johnsson, P.A., 1996, Theoretical considerations and a simple method for measuring alkalinity and acidity in low-pH waters by Gran titration: U.S. Geological Survey Water Resources Investigations Report 89-4029, 36 p. Brinton, T.I., Antweiler, R.C., and Taylor, H.E., 1995, Method for the determination of dissolved chloride, nitrate, and sulfate in natural water using ion chromatography: U.S. Geological Survey Open-File Report 95-426A, 16 p. Carter, R.W., and Davidian, J., 1968, General procedures for gaging streams: U.S. Geological Survey Techniques of Water-Resources Investigations, Book 3, Chapter A6, 13 p. Fishman, M.J., and Friedman, L.C., 1989, Methods for determination of inorganic substances in water and fluvial sediments: Techniques of Water-Resources Investigations of the U.S. Geological Survey, Book 5, Chapter A1, p. 55-56, 55-56 p. Roth, D.A., Johnson, M.O., McCleskey, R.B., Riskin, M.L., and Bliznik, P.A., 2022, Evaluation of preservation techniques for trace metals and major cations for surface waters collected from the U.S. Geological Survey's National Water Quality Network Sites: U.S. Geological Survey data release, https://doi.org/10.5066/P9SMPZ3M. Skogerboe, R.K., and Grant, C.L., 1970, Detection limits and sensitivities for spectroscopic methods: Spectroscopic Letters, v. 3, p. 215-219. U.S. Environmental Protection Agency, 2016, Definition and procedure for the determination of the method detection limit, revision 2: EPA 821-R-16-006, 6 p. 2021 The discharge using the specific conductance slug method can be determined using the accompanying spreadsheet (Discharge.xlxs). To use the spreadsheet, first select the salt from the pull-down menu (cell A4), determine the background SC (cell B7), input the SC collection interval in seconds (cell B8), add the salt mass (cell B9) used in the slug addition, and copy the measured SC at the monitoring sites into the spreadsheet beginning in cell B22. Finally, copy cells rows B12-R12 down to the end of the SC data. The discharge is reported in cells A14 (L/s), B14 (m3/s), and C14 (cfs). 20240102 If the salt mass was not pre-weighed prior to a site visit, the mass can be determined using the SaltMass.xlsx spreadsheet by first selecting the salt from the pull-down menu (cell A5), measuring the background SC (cell B8), measuring the SC of the concentrated salt solution once the salt has fully dissolved (cell B9), and recording the volume (cell A12). 20240102 0.0001 0.0001 Decimal degrees North American Datum of 1983 (NAD 83) Geodetic Reference System 1980 6378137.000000 298.257222 SlugAdditions.csv Comma Separated Value (CSV) file containing data. Producer Defined Slug_addition_test Unique number assigned to each slug addition Producer Defined 1 29 Location Stream or creek where slug addition was performed Producer Defined Stream or creek where slug addition was performed Latitude Latitude (NAD83) Producer Defined 37.8259 40.0187 degrees 0.0001 Longitude Longitude (NAD83) Producer Defined -119.468 -105.3263 degrees 0.0001 Slug_addition_date Date of slug addition Producer Defined Date of slug addition Slug_addition_time Time of slug addition (local) Producer Defined Time of slug addition (local) Salt Salt used in slug addition Producer Defined NaCl Sodium chloride Producer defined NaCl (Morton) Table salt Producer defined NaBr Sodium Bromide Producer defined KCl Potassium chloride Producer defined KBr Potassium bromide Producer defined LiCl Lithium chloride Producer defined Background_specific_conductance_microsiemens_per_centimeter Specific conductance of stream prior to slug addition Producer Defined 3 373 microsiemens per centimenter 1 Mass_grams mass of salt used in slug addition Producer Defined 206.32 2000.0 grams 0.01 Collection_interval_seconds The time between specific conductance measurements Producer Defined 2 4 seconds 1 Discharge_liters_per_second Streamflow or discharge Producer Defined 21.5 778.0 liters per second 0.1 Comparison_discharge_method Discharge method used to evaluate the discharge determined using slug addition and specific conductance Producer Defined Discharge method Comparison_discharge_liters_per_second Discharge determined by comparison method Producer Defined 21.3 801.0 liters per second 0.1 SlugAddition_SC.csv Comma Separated Value (CSV) file containing data. Producer Defined Slug_addition_number Unique number assigned to each slug addition Producer Defined 1 29 Location Stream or creek where slug addition was performed Producer Defined Stream or creek where slug addition was performed Slug_addition_date Date of slug addition Producer Defined Date of slug addition Slug_addition_time Time of slug addition (local) Producer Defined Time of slug addition (local) Elapse_ time_seconds Total time in seconds since the slug addition was added to the stream Producer Defined 0 5072 seconds 2 Specific_conductance_microsiemens_per_centimeter Specific conductance of stream downstream from addition site Producer Defined 3.06 573.0 microsiemens per centimeter 0.01 FourmileWQ.csv Comma Separated Value (CSV) file containing data. Producer Defined Sample_ID A unique identification number assigned to each discrete water sample Producer Defined A unique identification number assigned to each discrete water sample Location Stream or creek where sample was collected Producer Defined Stream or creek where sample was collected Slug_addition_test Unique number assigned to each slug addition Producer Defined << empty cell >> No Data Producer defined 22 29 Salt Salt used in slug addition Producer Defined Background No salt added Producer defined NaCl (Morton) Table Salt Producer defined NaCl Sodium chloride Producer defined NaBr Sodium bromide Producer defined KCl Potassium chloride Producer defined KBr Potassium bromide Producer defined LiCl Lithium chloride Producer defined specific_conductance_microsiemens_per_centimeter Specific conductance Producer Defined 374.0 450.3 microsiemens per centimeter 0.1 Calculated_specific_conductance_microsiemens_per_centimeter Calculate specific conductance using PHREEQCI Producer Defined 376 454 microsiemens per centimeter 1 Temperature_degrees_Celsius Water temperature Producer Defined 14.3 16.8 degrees Celsius 0.1 Sodium_milligrams_per_liter Concentration of sodium Producer Defined 14.1 28.7 milligrams per liter 0.1 Potassium_milligrams_per_liter Concentration of potassium Producer Defined 2.65 15.3 milligrams per liter 0.01 Calcium_milligrams_per_liter Concentration of calcium Producer Defined 35.7 37.9 milligrams per liter 0.1 Magnesium_milligrams_per_liter Concentration of magnesium Producer Defined 13.7 14.7 milligrams per liter 0.1 Silica_milligrams_per_liter Concentration of silica Producer Defined 12.7 13.9 milligrams per liter 0.1 Chloride_milligrams_per_liter Concentration of chloride Producer Defined 20.5 45.0 milligrams per liter 0.1 Sulfate_milligrams_per_liter Concentration of sulfate Producer Defined 50.9 51.7 milligrams per liter 0.1 Alkalinity_milligrams_bicarbonate_per_liter Concentration of alkalinity Producer Defined 123 131 milligrams per liter bicarbonate 1 Bromide_milligrams_per_liter Concentration of bromide Producer Defined <0.05 16.5 milligrams per liter 0.01 Nitrate_milligrams_per_liter Concentration of nitrate Producer Defined 0.08 0.08 milligrams per liter as NO3 0.01 Fluoride_milligrams_per_liter Concentration of fluoride Producer Defined 0.17 0.23 milligrams per liter 0.01 Aluminum_milligrams_per_liter Concentration of aluminum Producer Defined 0.005 0.006 milligrams per liter 0.001 Arsenic_milligrams_per_liter Concentration of arsenic Producer Defined < 0.02 < 0.02 milligrams per liter 0.01 Boron_milligrams_per_liter Concentration of boron Producer Defined 0.027 0.029 milligrams per liter 0.001 Barium_milligrams_per_liter Concentration of barium Producer Defined 0.0584 0.0660 milligrams per liter 0.0001 Beryllium_milligrams_per_liter Concentration of beryllium Producer Defined < 0.0005 < 0.0005 milligrams per liter 0.0001 Cadmium_milligrams_per_liter Concentration of cadmium Producer Defined < 0.002 < 0.002 milligrams per liter 0.001 Cobalt_milligrams_per_liter Concentration of cobalt Producer Defined < 0.002 < 0.002 milligrams per liter 0.001 Chromium_milligrams_per_liter Concentration of chromium Producer Defined < 0.001 0.001 milligrams per liter 0.001 Copper_milligrams_per_liter Concentration of copper Producer Defined < 0.001 0.001 milligrams per liter 0.001 Iron_milligrams_per_liter Concentration of iron Producer Defined 0.017 0.022 milligrams per liter 0.001 Lithium_milligrams_per_liter Concentration of lithium Producer Defined 0.008 2.91 milligrams per liter 0.001 Manganese_milligrams_per_liter Concentration of manganese Producer Defined < 0.001 < 0.001 milligrams per liter 0.001 Strontium_milligrams_per_liter Concentration of strontium Producer Defined 0.346 0.371 milligrams per liter 0.001 Zinc_milligrams_per_liter Concentration of zinc Producer Defined 0.005 0.006 milligrams per liter 0.001 Charge_balance_percent Calculated charge balance Producer Defined -2.8 1.0 percent 0.1 Discharge.xlsx Excel spreadsheet that calculates discharge using high-frequency specific conductance data collected downstream from a slug addition. Producer Defined SaltMass.xlsx Excel spreadsheet that calculates the salt mass used in the slug addition. Producer Defined 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 Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also contains copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner whenever applicable. The data have been approved for release and publication by the U.S. Geological Survey (USGS). 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 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. 20250113 R. Blaine McCleskey U.S. Geological Survey, WATER Research Chemist mailing address

3215 Marine St

Boulder CO 80303 US 303-541-3015 303-541-3084 rbmccles@usgs.gov Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998