Lambert, Rebecca B. Opsahl, Stephen P. Musgrove, MaryLynn 2017 v1.0 tabular digital data Data release 2017 Texas Water Science Center U.S. Geological Survey https://doi.org/10.5066/F7Q23Z5S Lambert, Rebecca B. Opsahl, Stephen P. Musgrove, 2017 v1.0 document Scientific Investigations Report 5121 Denver, CO U.S. Geological Survey Located in south-central Texas, the Geronimo Creek and Plum Creek watersheds have long been characterized by elevated nitrate concentrations. From April 2015 through March 2016, an investigation was done by the U.S. Geological Survey, in cooperation with the Guadalupe-Blanco River Authority (GBRA) and the Texas State Soil and Water Conservation Board (TSSWCB), to assess nitrate (as nitrogen) concentrations and to document possible sources of elevated nitrate as nitrogen in these two watersheds. Water-quality samples were collected from 20 groundwater, spring, and stream sites across the two watersheds, along with precipitation samples and wastewater treatment plant (WWTP) effluent samples from the Plum Creek watershed. Stream, spring, and groundwater samples were collected from both watersheds during four synoptic sampling events to characterize spatial and temporal variations in water quality and chemical loadings. Water-quality and quantity data from the wastewater treatment plants and stream discharge data were also considered. Samples were analyzed for major ions, selected trace elements, nutrients, stable isotopes of water and nitrogen isotopes. Data collected for this project was used to calculate selected chemical loadings and used in interpretation of sources of nitrate in both watersheds. The purpose of this data release is to document water-quality and chemical loading data collected for the Plum Creek Isotopes project in the Geronimo Creek and Plum Creek watersheds from April 2015 through March 2016. Water-quality data were collected from stream, spring, and groundwater sites from April through October 2015 (PlumCreek_QWData.txt). Additional data from a bulk precipitation collector and five wastewater treatment plants (WWTPs) located in the Plum Creek watershed also were collected from June 2015 through March 2016 and in April 2015, respectively (PlumCreek_QWData.txt). Quality-assurance data collected June 2015 through March 2016 also is included (PlumCreek_QAData.txt). Data on mean daily nitrate concentrations and effluent discharge values (variously dated, 2008-16) provided by the GBRA were used to calculate the effluent discharge contribution to the Plum Creek watershed (PlumCreek_WWTPLoads.txt). List of data files: PlumCreek_ReadMe.txt PlumCreek_SiteInformation.txt PlumCreek_CodeDefinitions.txt PlumCreek_FieldDefinitions.txt PlumCreek_QWData.txt PlumCreek_QAData.txt PlumCreek_RPDs.txt PlumCreek_QWLoads.txt PlumCreek_WWTPLoads.txt PlumCreek_DataTables_Combined.xlsx Metadata file: PlumCreek_Metadata.xml Note: These digital data accompany Lambert, R.B., Opsahl, S.P., and Musgrove, M., 2017, Water quality, sources of nitrate, and chemical loadings in the Geronimo Creek and Plum Creek watersheds, south-central Texas, April 2015—March 2016: U.S. Geological Survey Scientific Investigations Report 2017-5121, https://doi.org/10.3133/sir20175121 20150415 20160307 ground condition Complete None planned -98.16666667 -97.33333333 30.16666667 29.500000 None Water-quality sampling deuterium isotopic analysis oxygen isotopic analysis nitrogen isotopes analysis water chemistry hydrogeology nutrients nitrate sources USGS Metadata Identifier USGS:59bad30be4b091459a563d1d Geographic Names Information System Caldwell County Guadalupe County Buda Kyle Luling Lockhart Geronimo Creek Plum Creek south-central Texas None Texas Caldwell County Comal County Guadalupe County Hays County Geronimo Creek Plum Creek USGS Station ID 294011097575800 USGS Station ID 293851097570301 USGS Station ID 293802097563800 USGS Station ID 293739097565801 USGS Station ID 08172065 USGS Station ID 08172400 USGS Station ID 295309097400100 USGS Station ID 08172475 USGS Station ID 295228097440600 USGS Station ID 295220097432601 USGS Station ID 08172980 USGS Station ID 08173000 USGS Station ID 08173080 USGS Station ID 08173200 USGS Station ID 295204097384100 USGS Station ID 300519097503100 USGS Station ID 295805097500600 USGS Station ID 295303097394800 USGS Station ID 295212097373300 USGS Station ID 294108097374000 None Leona Formation fluviatile terrace deposits alluvium None There is no guarantee concerning the accuracy of these data. No warranty expressed or implied is made regarding the accuracy or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Users should be aware that temporal changes may have occurred since these data were collected or compiled for this study and that some parts of these data may no longer represent actual conditions. Users should not use this data for critical applications without a full awareness of its limitations. Acknowledgement of the U.S. Geological Survey would be appreciated in products derived from these data. Any user who modifies the data is obligated to describe the types of modifications they perform. User specifically agrees not to misrepresent the data, nor to imply that changes made were approved or endorsed by the U.S. Geological Survey. Texas Water Science Center Public Information Officer U.S. Geological Survey PIO - Public Information Office mailing and physical

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Austin TX 78754 USA 512-927-5300 512-927-3500 512-927-3590 gs-w-txpublic-info@usgs.gov The project was done in cooperation with the Guadalupe-Blanco River Authority (GBRA) and the Texas State Soil and Water Conservation Board (TSSWCB). The water-quality data were reviewed for accuracy and precision using historical water-quality data from these sites and quality-control samples collected during the study as a guide to determining attribute accuracy. Quality-control samples were collected and analyzed to help assess the variability and bias associated with the environmental sample results that might have occurred through the sampling and processing procedures. Quality-control samples submitted to the analytical laboratories included two field blanks and four split replicate samples. The blank samples were collected using blank water certified to contain concentrations of the constituents of interest that were less than the laboratory reporting level (LRL). Chloride, sulfate, and phosphorus were detected in at least one of the blank samples, but in concentrations much lower than were detected in the environmental concentrations. The blank data indicates that the sampling procedure and processing procedure have not affected the interpretation of the environmental results. Four split replicate sample pairs (environmental sample and replicate sample) were collected from surface-water, spring, and groundwater sites. The relative percent difference (RPD) was calculated for each replicate pair with concentrations greater than the LRL. Most of the RPDs were less than or equal to 4 percent, indicating acceptable reproducibility associated with sample processing and laboratory analysis. Ammonia, ammonia-N, and phosphorus had RPDs greater than 4 percent, but the concentrations of these constituents were low, near the LRL, which resulted in larger RPDs. The RPD results indicated that the sampling and analytical procedures were consistent and reproducible. Not applicable. 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. Water-quality samples were collected from a bulk precipitation collector, surface-water, spring, and groundwater sites in the Geronimo Creek and Plum Creek watersheds, south-central Texas during April 2015-March 2016. Additional water-quality samples were collected from five major wastewater treatment plants (WWTPs) in the Plum Creek watershed for comparison purposes in April 2015. Water-quality samples collected by the USGS followed the sampling protocols outlined in the USGS national field manual and associated publications and listed below: U.S. Geological Survey, variously dated, National field manual for the collection of water-quality data: U.S. Geological Survey Techniques of Water-Resources Investigations, book 9, chaps. A1–A10, accessed April 28, 2017, at http://pubs.water.usgs.gov/twri9A. Information on water quality in Geronimo Creek and Plum Creek watersheds and wastewater treatment plant samples collected 2008-16 by the Guadalupe-Blanco River Authority was used in the calculation of WWTP loads in the data tables and can be accessed online at: http://www.geronimocreek.org/ http://www.gbra.org/plumcreek/default.aspx The water-quality samples were analyzed for major ions, selected trace elements, and nutrients at the USGS National Water Quality Laboratory in Denver, Colorado. The water-quality samples were analyzed for stable isotopes of water and nitrogen at the USGS Stable Isotope Laboratory in Reston, Virginia. Unknown Quality-assurance samples (blanks and split replicates) were reviewed to determine variability and bias associated with sample collection and sample processing. Blank sample results indicated that the environmental results were not affected by contamination associated with sample collection or sample processing. The split replicate sample pairs were reviewed and the relative percent difference (RPD) between the environmental sample and the replicate sample to determine bias associated with sample analysis. The relative percent differences (RPDs) were calculated for each replicate pair having detectable concentrations by using the following equation: RPD = [|C1 – C2|/((C1 + C2)/2)] × 100 where C1 is the constituent concentration, in milligrams per liter, from the environmental sample; and C2 is the constituent concentration, in milligrams per liter, from the replicate sample. Unknown Chemical loadings were calculated. Water-quality constituent concentrations and instantaneous flow data collected at the time a water-quality sample or a wastewater treatment plant sample was collected were used to calculate instantaneous constituent loads for selected surface-water and spring sites in the Geronimo Creek and Plum Creek watersheds. Instantaneous constituent loads were calculated by using the following equation: CL = Qi × CC × k where CL is the instantaneous constituent load, in tons per day; Qi is the instantaneous streamflow, in cubic feet per second; CC is the constituent concentration, in milligrams per liter; and k is a unit conversion factor of 0.0027 in tons per day per cubic foot per second Information on water quality data collected 2008-16 by the Guadalupe-Blanco River Authority was used in the calculation of WWTP loads in the PlumCreek_WWTPLoads.txt data table and can be accessed online at http://www.gbra.org/plumcreek/default.aspx Unknown 0.0011 0.0011 Decimal degrees North American Datum of 1983 Geodetic Reference System 80 6378137 298.25722210088 PlumCreek_CodeDefinitions.txt Description of each code used in PlumCreek_QWData.txt, PlumCreek_QAData.txt, PlumCreek_RPDs.txt, PlumCreek_QWLoads.txt, and PlumCreek_WWTPLoads.txt. Code definitions are defined in the "Overview Descriptions" of the "Entity & Attribute" section. Project defined. PlumCreek_FieldDefinitions.txt Description of each field used in PlumCreek_SiteInformation.txt PlumCreek_QWData.txt., PlumCreek_QAData.txt, PlumCreek_RPDs.txt PlumCreek_QWLoads.txt, and PlumCreek_WWTPLoads.txt Project defined. PlumCreek_QWData.txt Water-quality sample results for environmental samples collected April 2015-March 2016 Project defined. PlumCreek_QAData.txt Water-quality sample results for quality-assurance samples including blanks and split replicate pairs collected April 2015-March 2016 Project defined PlumCreek_QWLoads.txt Chemical load calculations for water-quality samples collected April 2015-March 2016 by the USGS Project defined. PlumCreek_WWTPLoads.txt Chemical load calculations from wastewater treatment plant datasets provided by the Guadalupe-Blanco River Authority. Data available online at http://www.gbra.org/plumcreek/data.aspx Project defined. PlumCreek_DataTables_Combined.xlsx All .txt data tables with water-quality results, quality-assurance results, and constituent loadings combined into one EXCEL file. Each .txt data table is a separate tab in spreadsheet. Project defined. PlumCreek_ReadMe.txt Describes metadata documentation, description of each file available for download. Project defined. PlumCreek_SiteInformation.txt Description of site information including latitude and longitude. Project defined. PlumCreek_RPDs.txt Relative percent differences (RPDs) for split replicate sample pairs listed in PlumCreek_QAData.txt Project defined. Field, Description, Notes, and Units -99999, Null value indicator, dimensionless STAID, USGS station number, dimensionless SNAME, USGS station name, dimensionless SHORT_NAME, Short name, dimensionless STYPE, Water-quality sample type code, dimensionless MEDIM, Water-quality medium code, dimensionless COUNTY, County, dimensionless LATITUDE, latitude, NAD83, decimal degrees LONGITUDE, longitude, NAD83, decimal degrees OAQ, Artificial quality-control sample, blank, dimensionless WG, Groundwater sample, dimensionless WGQ, Groundwater quality-control sample, replicate, dimensionless WS, Surface water sample, dimensionless WSQ, Surface water quality-control sample, replicate, dimensionless DATES, Sample or measurement date, date, MMDDYYYY format TIMES, Sample start time, time, CST, 24 hour clock, HHMM format P00025, Barometric pressure, millimeters of mercury P00020, Temperature, air, degrees Celsius P72019, Depth to water level, feet below land surface P00061, Discharge, instantaneous, cubic feet per second P00300, Dissolved oxygen, water, unfiltered, milligrams per liter P00301, Dissolved oxygen, water, unfiltered, percent of saturation P00059, Flow rate, instantaneous, gallons per minute P00400, pH, water, unfiltered, field, standard units P00095, Specific conductance, water, unfiltered, microsiemens per centimeter at 25 degrees Celsius P00010, Temperature, water, degrees Celsius P63680, Turbidity, water, unfiltered, formazin nephelometric units (FNU) P70301, Dissolved solids, water, filtered, sum of constituents, milligrams per liter P00900, Hardness, water, milligrams per liter as calcium carbonate P00904, Noncarbonate hardness, water, filtered, field, milligrams per liter as calcium carbonate P00915, Calcium, water, filtered, milligrams per liter P00925, Magnesium, water, filtered, milligrams per liter P00935, Potassium, water, filtered, milligrams per liter P00931, Sodium adsorption ratio (SAR), water, number P00932, Sodium fraction of cations, water, percent in equivalents of major cations P00930, Sodium, water, filtered, milligrams per liter P39086, Alkalinity, water, filtered, inflection-point titration method (incremental titration method), field, milligrams per liter as calcium carbonate P00453, Bicarbonate, water, filtered, inflection-point titration method (incremental titration method), field, milligrams per liter P71870, Bromide, water, filtered, milligrams per liter P00405, Carbon dioxide, water, unfiltered, milligrams per liter P00452, Carbonate, water, filtered, inflection-point titration method (incremental titration method), field, milligrams per liter P00940, Chloride, water, filtered, milligrams per liter P00950, Fluoride, water, filtered, milligrams per liter P71834, Hydroxide, water, filtered, inflection-point titration method (incremental titration method), field, milligrams per liter P00955, Silica, water, filtered, milligrams per liter as SiO2 P00945, Sulfate, water, filtered, milligrams per liter P00623, Ammonia plus organic nitrogen, water, filtered, milligrams per liter as nitrogen P00625, Ammonia plus organic nitrogen, water, unfiltered, milligrams per liter as nitrogen P71846, Ammonia (NH3 + NH4+), water, filtered, milligrams per liter as NH4 P00608, Ammonia (NH3 + NH4+), water, filtered, milligrams per liter as nitrogen P00631, Nitrate plus nitrite, water, filtered, milligrams per liter as nitrogen P71851, Nitrate, water, filtered, milligrams per liter as nitrate P00618, Nitrate, water, filtered, milligrams per liter as nitrogen P71856, Nitrite, water, filtered, milligrams per liter as nitrite P00613, Nitrite, water, filtered, milligrams per liter as nitrogen P00607, Organic nitrogen, water, filtered, milligrams per liter as nitrogen P00605, Organic nitrogen, water, unfiltered, milligrams per liter as nitrogen P00671, Orthophosphate, water, filtered, milligrams per liter as phosphorus P00660, Orthophosphate, water, filtered, milligrams per liter as PO4 P00666, Phosphorus, water, filtered, milligrams per liter as phosphorus P00665, Phosphorus, water, unfiltered, milligrams per liter as phosphorus P00602, Total nitrogen [nitrate + nitrite + ammonia + organic-N], water, filtered, milligrams per liter P00600, Total nitrogen [nitrate + nitrite + ammonia + organic-N], water, unfiltered, milligrams per liter P01080, Strontium, water, filtered, micrograms per liter P01020, Boron, water, filtered, micrograms per liter P82082, delta hydrogen-2/hydrogen-1, water, unfiltered, per mil P82085, delta oxygen-18/oxygen-16, water, unfiltered, per mil P82690, delta nitrogen-15/nitrogen-14 of nitrate, water, filtered, per mil P63041, delta oxygen-18/oxygen-16 of nitrate, water, filtered, per mil RPD, relative percent difference, percent DS_Load, Dissolved-solids load, instantaneous, tons per day Cl_Load, Chloride load, instantaneous, tons per day SO4_Load, Sulfate load, instantaneous, tons per day NH4-N_Load, Ammonium load, instantaneous, tons per day NO3-N_Load, Nitrate as nitrogen load, instantaneous, tons per day NO2-N_Load, Nitrite as nitrogen load, instantaneous, tons per day OrgN_Load, Organic nitrogen load, instantaneous, tons per day Ortho-P_Load, Orthophosphate as phosphorus load, instantaneous, tons per day Phos_Load, Phosphorus load, instantaneous, tons per day Total-N_Load, Total nitrogen load, instantaneous, tons per day STAID_300519097503100_flow, flow for STAID 300519097503100, cubic feet per second STAID_300519097503100_nitrate-N, nitrate as nitrogen concentration for STAID 300519097503100, milligrams per liter STAID_300519097503100_nitrate-N_load, nitrate as nitrogen load for STAID 300519097503100, tons per day STAID_295805097500600_flow, flow for STAID 295805097500600, cubic feet per second STAID_295805097500600_nitrate-N, nitrate as nitrogen concentration for STAID 295805097500600, milligrams per liter STAID_295805097500600_nitrate-N_load, nitrate as nitrogen load for STAID 295805097500600, tons per day STAID_295303097394800_flow, flow for STAID 295303097394800, cubic feet per second STAID_295303097394800_nitrate-N, nitrate as nitrogen concentration for STAID 295303097394800, milligrams per liter STAID_295303097394800_nitrate-N_load, nitrate as nitrogen load for STAID 295303097394800, tons per day STAID_295212097373300_flow, flow for STAID 295212097373300, cubic feet per second STAID_295212097373300_nitrate-N, nitrate as nitrogen concentration for STAID 295212097373300, milligrams per liter STAID_295212097373300_nitrate-N_load, nitrate as nitrogen load for STAID 295212097373300, tons per day Total_Load_upstr_STAID_294108097374000, Total instantaneous nitrate-N load upstream of STAID 294108097374000, tons per day STAID_294108097374000_flow, flow for STAID 294108097374000, cubic feet per second STAID_294108097374000_nitrate-N, nitrate as nitrogen concentration for STAID 294108097374000, milligrams per liter STAID_294108097374000_nitrate-N_load, nitrate as nitrogen load for STAID 294108097374000, tons per day Total_Load_upstr_STAID_08173200, Total load entire watershed, tons per day Field, Description, Notes, and Units for all fields in Plum Creek data files Code Definition < Less than the long-term method detection limit or laboratory reporting level E Estimated Code definitions U.S. Geological Survey U.S. Geological Survey - Science Base mailing and physical

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Denver CO 80225 1-888-275-8747 sciencebase@usgs.gov Data Release 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 may contain copyrighted materials if 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 Director of the U.S. Geological Survey (USGS). Although these data have been subjected to rigorous review and are substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review. Furthermore, the data are released on the condition that neither the USGS nor the U.S. Government may be held liable for any damages resulting from authorized or unauthorized use. Although the data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. The U.S. Geological Survey or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Users of the data are advised to read all metadata and associated documentation thoroughly to understand appropriate use and data limitations. 20200827 Rebecca Lambert U.S. Geological Survey Hydrologist mailing and physical

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San Antonio TX 78249 210-691-9218 210-691-9270 blambert@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998