S. Jerrod Smith Nicole C. Gammill 20250625 Groundwater model Reston, Va. U.S. Geological Survey https://doi.org/10.5066/P1KASBTM Nicole C. Gammill S. Jerrod Smith 2025 publication n/a US Geological Survey https://doi.org/10.3133/sir20255043 The U.S. Geological Survey (USGS), in cooperation with the Oklahoma Water Resources Board (OWRB), constructed a finite-difference numerical groundwater-flow model of the Salt Fork Arkansas River and Chikaskia River alluvial aquifers by using MODFLOW-2005 with the Newton formulation solver (MODFLOW-NWT). The model included the Chikaskia River alluvial aquifer, which is classified as a minor aquifer by the OWRB and is hydrologically connected to the Salt Fork Arkansas River alluvial aquifer. The 1973 Oklahoma Groundwater Law requires that the OWRB conduct hydrologic investigations of the State’s aquifers to determine the maximum annual yield (MAY) for each groundwater basin. The MAY is defined as the total amount of fresh groundwater that can be annually withdrawn while allowing a minimum 20-year life of that groundwater basin. For alluvium and terrace groundwater basins, the life requirement is satisfied if, after 20 years of MAY withdrawals, 50 percent of the groundwater basin (hereinafter referred to as an “aquifer”) retains a saturated thickness of at least 5 feet. Once a MAY has been established, the amount of land owned or leased by a groundwater-use permit applicant determines the annual volume of water allocated to that groundwater-use permit applicant. The annual volume of groundwater allocated per acre of land is known as the equal-proportionate-share (EPS) pumping rate. At the time of this publication (2025), a hydrologic investigation and determination of the MAY for the Salt Fork Arkansas River alluvial aquifer had not been completed. The U.S. Geological Survey, in cooperation with the OWRB, conducted a hydrologic investigation and evaluated the simulated effects of potential groundwater withdrawals on groundwater flow and availability in the Salt Fork Arkansas River alluvial aquifer in northern Oklahoma for a study period spanning 1980–2020. Fifteen simulations are included in this data release: a simulation for the calibrated numerical groundwater-flow model, 9 scenario simulations to evaluate the EPS pumping rate, 4 scenario simulations to evaluate groundwater storage over a 50-year period, and 1 scenario simulation to evaluate effects of a hypothetical drought. This USGS data release contains all the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20255043). The numerical groundwater-flow models of the Salt Fork Arkansas River and Chikaskia River alluvial aquifers in this data release were developed to (1) estimate the EPS pumping rate that ensures a minimum 20-, 40-, and 50-year life of the aquifer, (2) quantify the potential effects of projected well withdrawals on groundwater storage over a 50-year period, and (3) simulate the potential effects of a hypothetical (10-year) drought on groundwater storage. The results of these groundwater-availability scenarios could be used by the OWRB to evaluate the maximum annual yield of groundwater from the Salt Fork Arkansas River alluvial aquifer in northern Oklahoma. The development of the model input and output files included in this data release are documented in the companion USGS Scientific Investigations Report 2025-5043 (https://doi.org/10.3133/sir20255043). Users are encouraged to review the model documentation report (https://doi.org/10.3133/sir20255043) to understand the purpose, construction, and limitations of this model. The model will run successfully only if the original directory structure is correctly restored. The model application data release is separated into several pieces to reduce the likelihood of download timeouts. Instructions for reconstructing the original directory structure and running the models included in this data release and described in the model documentation report can be found in the readme.txt file which can be downloaded as part of this data release. 19800101 20201231 ground condition Complete Not planned -98.963287 -97.016095 37.115964 36.431378 ISO 19115 Topic Category geoscientificInformation inlandWaters environment USGS Metadata Identifier USGS:65e6082ad34e5855ff4e66bc USGS Thesaurus groundwater groundwater and surface-water interaction modeling water resource management hydrology hydrogeology hydrologic processes water supply and demand water budget water use none usgsgroundwatermodel Groundwater Model MODFLOW-NWT MODFLOW Soil Water Balance PEST PEST++ Python Geographic Names Information System (GNIS) Salt Fork Arkansas River Chikaskia River Great Salt Plains Reservoir Alfalfa County Garfield County Grant County Kay County Noble County Woods County Oklahoma None. Acknowledgement of the USGS would be appreciated in products derived from this data release. These groundwater model input and output files are provided to support the analyses documented in the associated report (https://doi.org/10.3133/sir20255043). Although the information contained in the model files may be useful for other purposes, it is incumbent on the user to understand the purpose, construction, and limitations of this model. Data have been checked to ensure consistency with the accompanying report. If any errors are detected, please notify the originating office. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. Oklahoma-Texas Water Science Center Public Information Officer U.S. Geological Survey mailing and physical

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Austin TX 78754 USA 512-927-3500 otpublicinfo@usgs.gov Oklahoma Water Resources Board None Unclassified None Environment as of Metadata Creation: Microsoft Windows 10.0 (Build 17763); Esri ArcGIS 10.7.0 (Build 11595); Python 2.7.14 Niswonger, R.G. Panday, S. Ibaraki, M. 2011 Publication Techniques and Methods 6-A37 Reston, Va. U.S. Geological Survey Detailed descriptions of the model input and output file types, which are included in this data release, can be found in this code documentation report. https://doi.org/10.3133/tm6A37 Harbaugh, A.W. 1990 Publication Open-File Report 90-392 Reston, Va. U.S. Geological Survey Detailed descriptions of ZONEBUDGET file types, which are included in this data release, can be found in this documentation report. https://doi.org/10.3133/ofr90392 https://www.usgs.gov/software/zonebudget-program-computing-subregional-water-budgets-modflow-groundwater-flow-models White, J.T. 2018 Publication Environmental Modelling and Software 109 Amsterdam, Netherlands Elsevier Detailed descriptions of PEST++ iterative ensemble smoother output file types, which are included in this data release, can be found in this code documentation report. https://doi.org/10.1016/j.envsoft.2018.06.009 Welter, D.E. Doherty, J.E. Hunt, R.J. Muffels, C.T. Tonkin, M.J. Schreuder, W.A. 2012 Publication Techniques and Methods 7-C5 Reston, Va. U.S. Geological Survey Detailed descriptions of PEST++ input and output file types, which are included in this data release, can be found in this code documentation report. https://doi.org/10.3133/tm7c5 Westenbroek, S.M. Kelson, V.A. Dripps, W.R. Hunt, R.J. Bradbury, K.R. 2010 Publication Techniques and Methods 6-A31 Reston, Va. U.S. Geological Survey Detailed descriptions of SWB input and output file types, which are included in this data release, can be found in this code documentation report. https://doi.org/10.3133/tm6A31 U.S. Geological Survey 2024 publication https://doi.org/10.5066/F7P55KJN https://waterdata.usgs.gov/ok/nwis/ Harbaugh, A.W. 2005 publication Techniques and Methods 6-A16 Reston, Va. US Geological Survey Detailed descriptions of the model input and output file types, which are included in this data release, can be found in this code documentation report. https://doi.org/10.3133/tm6A16 Oklahoma Water Resources Board 2022 publication https://oklahoma.gov/owrb/data-and-maps/gis-data.html Natural Resources Conservation Service 2022 publication https://www.nrcs.usda.gov/resources/data-and-reports/soil-survey-geographic-database-ssurgo Niswonger, R.G. Prudic, D.E. 2005 publication U.S. Geological Survey Techniques and Methods 6-A13 https://doi.org/10.3133/tm6A13 Multi-Resolution Land Characteristics Consortium 2011 publication https://www.mrlc.gov/data?f[0]=category:Land%20Cover Thornthwaite, C.W. Mather, J.R. 1957 publication Centerton, N.J. Drexel Institute of Technology, Laboratory of Climatology, Publications in Climatology v. 10, no. 3, p. 185–311 https://www.wrc.udel.edu/wp-content/publications/ThornthwaiteandMather1957Instructions_Tables_ComputingPotentialEvapotranspiration_Water%20Balance.pdf Engineering Enterprises, Inc. 1977 publication Noman, Okla. Engineering Enterprises, Inc. Doherty, J.E. 2010 publication Brisbane, Australia Watermark Numerical Computing https://pesthomepage.org/programs The numerical groundwater-flow model was calibrated to water-table-altitude observations at selected wells, monthly base-flow observations at selected streamgages, and selected components of a conceptual-model water budget. A total of 1,261 water-table-altitude observations (OWRB, 2022; USGS, 2024) from 68 wells were used as calibration targets for the transient simulation. Water-table-altitude observations from the transient simulation were temporally averaged by well to derive 68 calibration targets for the steady-state simulation because no observations were available near the beginning of the modeling period (1980). Base-flow observations (./ancillary/Table2_SFAR_EstimatedBaseFlows.csv) were available for 492 months (the full numerical model period) at the Tonkawa gage on the Salt Fork Arkansas River (USGS streamgage 07151000), 86 months at the State Highway 11 gage on the Salt Fork Arkansas River (USGS streamgage 07149520), and 483 months at the Blackwell gage on the Chikaskia River (USGS streamgage 07152000). Base-flow observations were available for 491 months at the Alva gage on the Salt Fork Arkansas River (USGS streamgage 07148400), but only the first 165 months were used as calibration targets because the remaining months were used to formulate Salt Fork Arkansas River inflows. Base-flow records also were available for the period (2017–20) at the OWRB White Eagle gage (collocated with USGS streamgage 07152260; ./ancillary/Table5_SFAR_OWRBWhiteEagleGageData.csv) on the Salt Fork Arkansas River, which was located near the downgradient (eastern) end of the model active area. However, base-flow records at that streamgage were used to calculate a scaling factor (1.1) by which monthly base flows (483 months) could be estimated from summed base-flow observations at the Tonkawa gage on the Salt Fork Arkansas River and the Blackwell gage on the Chikaskia River. The monthly mean base flows for these five streamgages, accounting for 1,709 observations, were used as calibration targets for the transient simulation. The mean annual base flows for the five streamgages, accounting for five observations, were used as calibration targets for the steady-state simulation. Data from other streamgages were unused as calibration targets because they were used as model inputs. The calibration process for the numerical model included both manual and automated adjustment of parameters. The manual calibration was primarily focused on aligning the numerical-model water budget to the conceptual-model water budget. The automated calibration approach was focused solely on minimizing residuals and used the PEST++ Iterative Ensemble Smoother (White, 2018; White and others, 2020) to reduce run times associated with the calibration of highly parameterized models. No formal logical consistency tests were conducted. Values were checked for correct data types. All data match the information provided by their associated metadata and reported values fall within the expected ranges. Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the metadata record and the associated model documentation report for this data release (https://doi.org/10.3133/sir20255043) for additional details. No formal positional accuracy tests were conducted. No formal positional accuracy tests were conducted. The process used to develop, calibrate, and apply the groundwater flow model is fully described in the model documentation report (https://doi.org/10.3133/sir20255043). 2025 Raster Grid Cell 300 700 1 Albers Conical Equal Area 29.5 45.5 -96.0 23.0 0.0 0.0 row and column 800 800 meters North American Datum of 1983 Geodetic Reference System 1980 (GRS 80) 6378137 298.257 North American Vertical Datum of 1988 0.01 feet Attribute values sir2025_5043.zip Compressed (.zip) folder containing a collection of files with a common filename prefix (sir2025_5043) associated with the feature class (shapefile; .shp) containing information on the model domain. U.S. Geological Survey FID Sequential unique whole numbers that are automatically generated for each feature. ESRI 0 The unique whole number assigned to the polygon in the feature class related to the inactive area of the model domain. ESRI 1 The unique whole number assigned to the polygon in the feature class related to the active area of the model domain. ESRI Shape Feature geometry or shape type. ESRI Polygon A polygon consists of one or more rings where a ring is a connected sequence of three or more points that form a closed, non-self-intersecting loop. ESRI Area Text string indicating whether the model domain is active or inactive https://doi.org/10.3133/sir20255043 Inactive Delineation of the inactive area in the model https://doi.org/10.3133/sir20255043 Active Delineation of the active area in the model https://doi.org/10.3133/sir20255043 This model application data release contains all the model input and output files needed to replicate the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20255043). Individual files in this data release include: -readme.txt: This file provides an organizational outline of the model application folder structure and the files contained in each subfolder, instructions for reconstructing the model application from the downloaded model files, descriptions of each model, and instructions for running the models. -modelgeoref.txt: This text file defines the coordinates of the four corners of the model domain in decimal degrees (referenced to the North American Datum of 1983) and in feet (referenced to a custom Albers Equal-Area projection). Model data files are presented in the custom Albers Equal-Area projection with units of feet. -ancillary.zip, ancillary2.zip, ancillary3.zip: These ZIP files, which should all be extracted to a ./ancillary folder, contain ancillary data files (compressed into three separate zip files to decrease the likelihood of download timeouts) that may aid in the interpretation of model results including ZONEBUDGET outputs for the drought scenario, 20-, 40-, and 50-year EPS scenarios, and the calibrated final model; PEST instruction and template files; files used to generate pilot points for interpolating model hydraulic conductivity; files used to generate the model Streamflow-routing (SFR2) package files; files used to generate the model Well (WEL) package files; the Soil-Water-Balance (SWB) code used to compute and distribute recharge to model cells; PEST files used to calibrate the final model, compute EPS pumping rates, and calculate observation sensitivities; more detailed versions of tables that appear in the model documentation report; information from a historical multi-well aquifer test; and preprocessing and post-processing Python scripts (.py) with initialization (.ini) files. Python scripts have been included in the model application as a courtesy to the user to illustrate the workflow. Scripts will need to be updated by the user to run in the model application structure on the user's computer. -bin.zip: This ZIP file contains the compiled executable codes used to run all simulation scenarios documented in the report. The compiled executable codes include MODFLOW-NWT (version 1.2.0), PEST (version 17.05), PEST++ (version 4.0.1), PEST++_IES (version 4.2.16), SWB (version 1.0.1), and ZONEBUDGET (version 3.01). The Python (version 2.7.14) executable is only in the ./source folder because it does not work when separated from supporting files. -SIR2025_5043.zip: This ZIP file contains a polygon shapefile showing the active and inactive areas of the model domain. -model.zip: This ZIP file contains input, control, and batch (run) files for the calibrated final model and model scenarios (projected-pumping, drought, and equal-proportionate-share [EPS]) and common files used by all models (externalfiles). Detailed information about these scenarios is provided in the model documentation report and the readme.txt file of this model application data release. -output.zip: This ZIP file contains output files for the calibrated final model and model scenarios (projected-pumping, drought, and equal-proportionate-share [EPS]). Detailed information about these scenarios is provided in the model documentation report and the readme.txt file of this model application data release. -source.zip: This ZIP file contains standard model source codes and associated files for MODFLOW-NWT (version 1.2.0), Python (version 2.7.14), PEST (version 17.05), PEST++ (version 4.0.1), PEST++_IES (version 4.2.16), SWB (version 1.0.1), and ZONEBUDGET (version 3.01). The Python 2.7.14 source code is a portable, packaged version of Python that does not require installation of Python on the user's system. https://doi.org/10.3133/sir20255043 GS ScienceBase U.S. Geological Survey mailing and physical

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Denver CO 80225 USA 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 the data, software, and related material have been processed successfully on a computer system at the USGS, 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. Although the 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 shall be held liable for any damages resulting from authorized or unauthorized use. The USGS or the U.S. Government shall not be held liable for improper or incorrect use of the data described and/or contained herein. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Digital datasets None 2636 https://doi.org/10.5066/P1KASBTM None. No fees are applicable for obtaining the dataset. 20250625 S. Jerrod Smith U.S. Geological Survey Hydrologist mailing and physical

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Oklahoma City OK 73116 USA 405-810-4400 sjsmith@usgs.gov FGDC Content Standard for Digital Geospatial Metadata FGDC-STD-001-1998