Alison D. Gordon Ryan S. Frederiks Jason P. Pope 20260116 water budgets Reston, VA U.S. Geological Survey https://doi.org/10.5066/P13GJEYW Jason P. Pope Alison D. Gordon Ryan S. Frederiks 2026 Publication Preprint 1 Reston,VA U.S. Geological Survey https://doi.org/10.31223/X5HB5D This data release contains results from annual water budgets computed for two groundwater-flow models of the Virginia Coastal Plain published by the Virginia Department of Environmental Quality (Virginia Department of Environmental Quality, 2020, 2024a and 2024b). Both models simulated historical withdrawals from approximately 1900 to 2023 and projected withdrawal conditions to 2073. Decades of substantial groundwater withdrawals from the Virginia Coastal Plain aquifer system have altered the groundwater-flow system from pre-development conditions which has the potential to threaten groundwater resources for current and future water users by depleting aquifer storage. Computation of detailed groundwater budgets enables quantification and better understanding of this important resource for current and future management and development. This U.S. Geological Survey data release contains the input and output files for the water-budget analyses using the U.S. Geological Survey ZONEBUDET program (Harbaugh, 2009) for the eight simulations described in the associated report (https://doi.org/10.31223/X5HB5D). The ZONEBUDGET program was used to assess water budgets for eight simulations for the hydrogeologic units and Geographic Budget Regions in the Virginia Coastal Plain aquifer system. These simulations were used to analyze historical, current and projected groundwater withdrawals on the Coastal Plain aquifer system for the time period 1899-2073. Understanding the affects of withdrawals over time on the aquifer system is essential for the Virginia Department of Environmental Quality for planning water-allocation strategies. The ZONEBUDGET program input and output files included in this data release are documented in the U.S. Geological Survey Open-File Report (https://doi.org/10.31223/X5HB5D). Support is provided for correcting errors in the data release by the U.S. Geological Survey. The programs will run successfully only if the original directory structure is correctly restored. The archive is broken into several pieces to reduce the likelihood of download timeouts. Instructions for reconstructing the original directory structure and running the programs included in this data release and described in the documentation report can be found in the readme.txt ASCII file which can be downloaded as part of this data release. Files in this data release include: -readme.txt: This ASCII text file describes the archive data release including the archive folder structure and files contained within each subfolder. This file also includes instructions on how to run the models contained in this data release. -ancillary.zip: ZIP file containing the Python programs and scripts to produce ZONEBUDGET outputs for each simulation. -bin.zip: ZIP file containing the 64-bit executable for ZONEBUDGET (version 3_01) used to do the analyses documented in this data release. -georef.zip: ZIP fle containing outline of model grid. -BudgetAnalysis.zip: ZIP file containing the input and output files for each withdrawal simulation documented in this data release. -source.zip: ZIP file containing source files for standard code version of ZONEBUDGET (version 3_01). 18990101 20731231 publication date Complete None planned -77.534 -74.769 38.384 36.100 ISO 19115 Topic Category geoscientificInformation inlandWaters USGS Thesaurus water budget none usgsgroundwatermodel ZONEBUDGET Groundwater Model USGS Metadata Identifier USGS:68daed39d4be021b36eb6708 Geographic Names Information System Virginia Accomack County Caroline County Charles City County Chesterfield County Essex County Gloucester County Greensville County Hanover County Henrico County Isle of Wight County King and Queen County King George County King William County Lancaster County Mathews County Middlesex County New Kent County Northampton County Northumberland County Prince George County Richmond County Southampton County Spotsylvania County Stafford County Surrey County Sussex County Westmoreland County York County Maryland North Carolina none Virginia Coastal Plain These ZONEBUDGET input and output files are provided to support the analyses documented in the associated report (https://doi.org/10.31223/X5HB5D). Although the information contained in the 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. none Jason P. Pope U.S. Geological Survey mailing and physical

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Richmond VA 23228 USA 765-577-0705 jpope@usgs.gov Virginia Department of Environmental Quality None Unclassified None Charles E. Heywood Jason P. Pope 2009 Publication Reston, Va. U.S. Geological Survey https://doi.org/10.3133/sir20095039 Ward E. Sanford Jason P. Pope David L. Nelms 2009 Publication Reston, Va. U.S. Geological Survey https://doi.org/10.3133/sir20095066 Christian D. Langevin W. Barclay Shoemaker Weixing Guo 2023 publication Reston, Va. U.S. Geological Survey https://fl.water.usgs.gov/Abstracts/ofr03_426_langevin.html In 2009, the calibration of the Virginia Coastal Plain and the Eastern Shore groundwater models were documented in two published U.S. Geological Survey reports (Heywood and Pope, 2009 and Sanford and others, 2009, respectively). The Virginia Coastal Plain model was calibrated to 7,183 historic water-level observations from 497 observation wells with the parameter-estimation codes UCODE–2005 (Poeter and others, 2005) and PEST (Doherty, 2004). The Eastern Shore model was calibrated using the U.S. Geological Survey code SEAWAT (Langevin and others, 2003) to simulate both water levels and concentrations of chloride (representing salinity) and UCODE (Poeter and Hill, 1998). Since the publication of the Virginia Coastal Plain and Eastern Shore groundwater models by U.S. Geological Survey, both models have been used by the Virginia Department of Environmental Quality (VADEQ) for water-supply planning, management, and regulation. The models have been updated annually with the current groundwater withdrawals and other input data. The updated models of the Virginia Coastal Plain and Eastern Shore are maintained and used by the VADEQ and are known as the VAHydroGW-VCP and VAHydroGW-VAES models, respectively. In 2019, the VAHydroGW-VCP model was recalibrated by the Aquaveo consulting firm for the Virginia Department of Environmental Quality to improve the match between simulated and measured groundwater levels. Both models simulate historical withdrawal conditions to 2023 and project groundwater conditions 50 years into the future to 2073, assuming the continuation of current pumping and environmental conditions. The documentation of the Virginia Coastal Plain model recalibration is available online from the Virginia Department of Environmental Quality, 2020. The groundwater model digital files can be obtained through written communication with Eric Seavey, Manager of the Office of Water Withdrawal Permitting for VADEQ (Eric.Seavey@deq.virginia.gov). VADEQ has published reports for simulations through 2023 for both the Virginia Coastal Plain groundwater model (Virginia Department of Environmental Quality, 2024a) and the Eastern Shore groundwater model (Virginia Department of Environmental Quality, 2024b). References: -Doherty, John, 2004, PEST model-independent parameter estimation (5th ed.): Corinda, Australia, Watermark Numerical Computing, 336 p. -Heywood, C.E., and Pope, J.P., 2009, Simulation of groundwater flow in the coastal plain aquifer system of Virginia: U.S. Geological Survey Scientific Investigations Report 2009–5039, 115 p., http://pubs.er.usgs.gov/publication/sir20095039. -Langevin, C.D., Shoemaker, W.B., and Guo, W., 2003, MODFLOW-2000, the U.S. Geological Survey Modular Ground-Water Model–Documentation of the SEAWAT-2000 Version with the Variable-Density Flow Process (VDF) and the Integrated MT3DMS Transport Process (IMT): U.S. Geological Survey Open-File Report 03-426, 43 p., https://doi.org/10.3133/ofr03426. -Poeter, E.P., Hill, M.C., and Banta, E.R., 2005, UCODE_2005 and six other computer codes for universal sensitivity analysis, calibration, and uncertainty evaluation: U.S. Geological Survey Techniques and Methods, book 6, chap. 11, 283 p. -Sanford, W.E., Pope, J.P., and Nelms, D.L., 2009, Simulation of groundwater-level and salinity changes in the Eastern Shore, Virginia: U.S. Geological Survey Scientific Investigations Report 2009– 5066, 125 p., http://pubs.er.usgs.gov/publication/sir20095066. -NOTE-The model files are obtained by written communication with Eric Seavey, Manager of the Office of Water Withdrawal Permitting for Virginia. -Virginia Department of Environmental Quality, 2020, 2019 update and recalibration of the VAHydroGW-VCPM,86 p. accessed September 5, 2025 at https://www.deq.virginia.gov/home/showpublisheddocument/27226/638702936855630000. -Virginia Department of Environmental Quality, 2024a, Virginia Coastal Plain model(VAHydroGW-VCPM 2023-2024 annual simulation of potentiometric surface elevations of reported and total permitted use, 53 p, accessed September 5, 2025 at https://www.deq.virginia.gov/home/showpublisheddocument/27228/638702936855630000. -Virginia Department of Environmental Quality, 2024b, Virginia Coastal Plain model(VAHydroGW-ES) 2023-2024 annual simulation of report use ad total permitted groundwater levels, 32 p, accessed September 5, 2025 at https://www.deq.virginia.gov/home/showpublisheddocument/27228/638702936863430000. No formal logical accuracy tests were conducted Dataset is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record and the associated model documentation reports from the Virginia Department of Environmental Quality which can be obtained by written communication with Eric Seavey, Manager of the Office of Water Withdrawal Permitting for Virginia. No formal positional accuracy tests were conducted No formal positional accuracy tests were conducted The process used to develop, calibrate, and apply the model is fully described in the model documentation reports from the Virginia Department of Environmental Quality which can be obtained by written communication with Eric Seavey, Manager of the Office of Water Withdrawal Permitting for Virginia. 2025 This ZONEBUDGET application data release contains all the model input and output files needed to replicate the simulations described in the associated documentation report (https://doi.org/10.31223/X5HB5D). https://doi.org/10.31223/X5HB5D Detailed descriptions of the program input and output files can be found in the documentation (https://doi.org/10.3133/tm6A16) and online at: https://water.usgs.gov/nrp/gwsoftware/modflow2000/MFDOC/index.html accessed September 24, 2025. https://doi.org/10.3133/tm6A16 GS ScienceBase U.S. Geological Survey mailing and physical

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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 the data, software, and related material have been processed successfully on a computer system at the U.S. Geological Survey (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 2032.388 https://doi.org/10.5066/P13GJEYW None. No fees are applicable for obtaining the dataset. 20260120 U.S. Geological Survey VA-WV Water Science Center Data Release Manager mailing and physical

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Richmond VA 23228 USA 804-261-2600 gs-w-nj_datarelease@usgs.gov FGDC Content Standards for Digital Geospatial Metadata FGDC-STD-001-1998