This data release includes a polygon shapefile of grid cells attributed with values representing the simulated base-flow, evapotranspiration, and groundwater-storage depletions as a percentage of hypothetical well pumpage for the 2011-2060 time period. Depletions were simulated by the Phase-Three Elkhorn-Loup Model (ELM), constructed using MODFLOW-NWT (Niswonger and others, 2011). Each polygon represents one model grid cell, with pumping specified from either layer one or layer two of the model. All values are estimates and approximations. The phase three ELM simulated the High Plains aquifer in north-central Nebraska from predevelopment (pre-1895) through 2060 (Flynn and Stanton, 2018). The simulation was calibrated using an automated parameter-estimation method to optimize the fit of simulation outputs to three sets of calibration targets: estimated 1940 groundwater levels and base flows (representing pre-1940 conditions), 1940-through-2010 monthly groundwater levels, and 1940 through 2010 monthly estimated base flows. The calibrated simulation was used to estimate volumetric ratios of the reductions in base flow, evapotranspiration, and groundwater storage to the total volume of water pumped from a hypothetical well for a 50-year future time period. Ratios were then multiplied by 100 to obtain percentages. The 50-year period was selected because base-flow depletion percentages for 40- to 50-year periods are the basis of groundwater and surface-water management decisions in Nebraska.

This data release includes a polygon shapefile of grid cells attributed with values representing the simulated base-flow, evapotranspiration, and groundwater-storage depletions as a percentage of hypothetical well pumpage for the 2006-2055 time period. Depletions were simulated by the Phase-Two Elkhorn-Loup Model (ELM), constructed using MODFLOW-2005 (Harbaugh, 2005) with the Groundwater Vistas, version 5, software (Environmental Simulations, Inc., 2009). Each polygon represents one model grid cell. All values are estimates and approximations. The Phase-Two ELM simulated the High Plains aquifer in north-central Nebraska from predevelopment (pre-1895) through 2055 (Stanton and others, 2010). The simulation was calibrated using an automated parameter-estimation method to optimize the fit of simulation outputs to three sets of calibration targets: estimated 1939 groundwater levels and base flows (representing pre-1940 conditions), 1945-through-2005 decadal groundwater-level changes, and 1940-through-2005 annual base flows. The calibrated simulation was used to estimate volumetric ratios of the reductions in base flow, evapotranspiration, and groundwater storage to the total volume of water pumped from a hypothetical well for a 50-year future time period. Ratios were then multiplied by 100 to obtain percentages. The 50-year period was selected because base-flow depletion percentages for 40- to 50-year periods are the basis of groundwater and surface-water management decisions in Nebraska.

This data release includes a polygon shapefile of grid cells attributed with values representing the simulated base-flow, evapotranspiration, and groundwater-storage depletions as a percentage of hypothetical well pumpage for the 2006-2055 time period. Depletions were simulated by the Phase-Two Elkhorn-Loup Model (ELM), constructed using MODFLOW-2005 (Harbaugh, 2005) with the Groundwater Vistas, version 5, software (Environmental Simulations, Inc., 2009). Each polygon represents one model grid cell. All values are estimates and approximations. The Phase-Two ELM simulated the High Plains aquifer in north-central Nebraska from predevelopment (pre-1895) through 2055 (Stanton and others, 2010). The simulation was calibrated using an automated parameter-estimation method to optimize the fit of simulation outputs to three sets of calibration targets: estimated 1939 groundwater levels and base flows (representing pre-1940 conditions), 1945-through-2005 decadal groundwater-level changes, and 1940-through-2005 annual base flows. The calibrated simulation was used to estimate volumetric ratios of the reductions in base flow, evapotranspiration, and groundwater storage to the total volume of water pumped from a hypothetical well for a 50-year future time period. Ratios were then multiplied by 100 to obtain percentages. The 50-year period was selected because base-flow depletion percentages for 40- to 50-year periods are the basis of groundwater and surface-water management decisions in Nebraska.

This data release includes a polygon shapefile of grid cells attributed with values representing the simulated base-flow, evapotranspiration, and groundwater-storage depletions as a percentage of hypothetical well pumpage for the 2006-2055 time period. Depletions were simulated by the Phase-Two Elkhorn-Loup Model (ELM), constructed using MODFLOW-2005 (Harbaugh, 2005) with the Groundwater Vistas, version 5, software (Environmental Simulations, Inc., 2009). Each polygon represents one model grid cell. All values are estimates and approximations. The Phase-Two ELM simulated the High Plains aquifer in north-central Nebraska from predevelopment (pre-1895) through 2055 (Stanton and others, 2010). The simulation was calibrated using an automated parameter-estimation method to optimize the fit of simulation outputs to three sets of calibration targets: estimated 1939 groundwater levels and base flows (representing pre-1940 conditions), 1945-through-2005 decadal groundwater-level changes, and 1940-through-2005 annual base flows. The calibrated simulation was used to estimate volumetric ratios of the reductions in base flow, evapotranspiration, and groundwater storage to the total volume of water pumped from a hypothetical well for a 50-year future time period. Ratios were then multiplied by 100 to obtain percentages. The 50-year period was selected because base-flow depletion percentages for 40- to 50-year periods are the basis of groundwater and surface-water management decisions in Nebraska.

A previously published MODFLOW-NWT groundwater-flow model for the Rush Springs aquifer in western Oklahoma (using 1 steady state stress period followed by 444 monthly stress periods representing 1979-2015; Ellis, 2018a) was used as the basis of several groundwater-use scenarios. The model is a 3-layer model including the Cloud Chief formation (confining unit of the Rush Springs aquifer), alluvial and terrace deposits, and the Rush Springs aquifer. The scenarios were used to assess the effects of increasing groundwater withdrawals from the Rush Springs aquifer on base flows to streams that flow into Fort Cobb Reservoir to address concerns over groundwater use reducing inflows to the lake. The effects of groundwater use on base flow were assessed using four scenarios: (1) scaling the equal-proportionate-share rate estimated by Ellis (2018a), (2) scaling historical groundwater withdrawals, (3) scaling historical groundwater withdrawals using zones, and (4) base flow depletion simulations. This USGS data release contains all input and output files for the groundwater-flow simulations and streamflow and base-flow statistics described in the associated model documentation report (https://doi.org/10.3133/sir20245002). Supporting geospatial data are provided that were used to help construct the scenarios and used to display model outputs.

A previously published MODFLOW-NWT groundwater-flow model for the Rush Springs aquifer in western Oklahoma (using 1 steady state stress period followed by 444 monthly stress periods representing 1979-2015; Ellis, 2018a) was used as the basis of several groundwater-use scenarios. The model is a 3-layer model including the Cloud Chief formation (confining unit of the Rush Springs aquifer), alluvial and terrace deposits, and the Rush Springs aquifer. The scenarios were used to assess the effects of increasing groundwater withdrawals from the Rush Springs aquifer on base flows to streams that flow into Fort Cobb Reservoir to address concerns over groundwater use reducing inflows to the lake. The effects of groundwater use on base flow were assessed using four scenarios: (1) scaling the equal-proportionate-share rate estimated by Ellis (2018a), (2) scaling historical groundwater withdrawals, (3) scaling historical groundwater withdrawals using zones, and (4) base flow depletion simulations. This USGS data release contains all input and output files for the groundwater-flow simulations and streamflow and base-flow statistics described in the associated model documentation report (https://doi.org/10.3133/sir20245002). Supporting geospatial data are provided that were used to help construct the scenarios and used to display model outputs.

A three-dimensional groundwater flow model was developed to characterize groundwater resources of the uppermost principal aquifers in the Williston structural basin in parts of Montana, North Dakota, and South Dakota in the United States and of Manitoba and Saskatchewan in Canada as part of a detailed assessment of the groundwater availability of the area. The uppermost principal aquifers are comprised of the glacial, lower Tertiary, and Upper Cretaceous aquifer systems. The model was developed as a part of the U.S. Geological Survey Water Availability and Use Science Program's effort to conduct large-scale multidisciplinary regional studies of groundwater availability. The numerical model was used to (1) simulate hydrologic scenarios of interest to groundwater managers and to advance the understanding of groundwater budgets and components including recharge, discharge, and aquifer storage for the entire system, (2) compute historical and projected system response to natural and anthropogenic stresses, and (3) evaluate potential hydrologic monitoring programs at a scale relevant to basin-wide water-management decisions. This model was previously published by the U.S. Geological Survey in a Scientific Investigations Report (https://doi.org/10.3133/sir20175158) and the model input and output files are available in a data release (https://doi.org/10.5066/F75B01CZ). The underlying directories contain all of the input and output files for predictive simulations of groundwater response to selected scenarios for the uppermost principal aquifer systems in the Williston Basin, United States and Canada. The predictive simulations were created using base model files from a model developed by Davis and Long and documented in the U.S. Geological Survey Scientific Investigations Report 2017-5158 (https://doi.org/10.3133/sir20175158). Model archive files are documented and are available in an online data release (https://doi.org/10.5066/F75B01CZ). The three-dimensional groundwater-flow model was developed using the numerical modeling software, MODFLOW-NWT. For this study, the numerical groundwater-flow model was used to simulated three predictive scenarios: scenario 1 was focused on flowing artesian wells, and was used to simulate 1960‒2035 hydraulic-head changes that would result if none of the flowing artesian wells in the model area were capped or plugged during this period and other conditions remained constant; scenario 2 simulated 10-year drought for 2006‒15, with no increases in groundwater pumping after 2005; and scenario 3 was identical to scenario 2, except that it also applied the increased groundwater withdrawals necessary to fill the needs of energy-resource production for 2006‒15. A data-worth analysis for evaluation of potential hydrologic monitoring networks was also accomplished using the numerical model. This USGS data release contains all of the input and output files for the model described in the associated model documentation report (https://doi.org/10.3133/pp1841). This data release also includes MODFLOW-NWT (version 1.0.9) source code.

In 2018 The U.S. Geological Survey, in cooperation with the U.S. Bureau of Reclamation and the Oklahoma Water Resources Board, published a calibrated numerical groundwater- flow model and associated model documentation report that evaluated the effects of potential groundwater withdrawals on groundwater flow and availability in the Rush Springs aquifer in western Oklahoma. The results of groundwater-availability scenarios run on the calibrated numerical groundwater-flow model could be used by the Oklahoma Water Resources Board to evaluate the maximum annual yield of groundwater from the Rush Springs aquifer in Oklahoma. A conceptual groundwater-flow model is a simplified description of the major inflow and outflow sources (hydrologic boundaries) of a groundwater-flow system as well as an accounting of the estimated mean flows from those sources (water budget) for a specified period of time. The conceptual model was necessary to provide constraints used in the construction and calibration of a scientifically defensible numerical groundwater-flow model that reasonably represents the groundwater-flow system. A finite-difference numerical groundwater-flow model of the Rush Springs aquifer was constructed by using MODFLOW-2005 with the Newton formulation solver (MODFLOW-NWT). Data inputs for each package were specified in machine-readable text files. The numerical model of the Rush Springs aquifer had 1,362 rows, 1,083 columns, about 554,000 active cells of 500 by 500 ft, and 3 convertible layers. The top layer (layer 1) represented the Permian-age Cloud Chief Formation. The Rush Springs aquifer is composed of Permian-age Whitehorse Group. The second layer (layer 2) represented the undifferentiated Quaternary-age alluvium and terrace deposits, as well as the upper 30 ft of the Whitehorse Group. The bottom layer (layer 3) represented the remainder of the Rush Springs Formation. The model active area was modified from Neel and others (2018). The numerical model was temporally discretized into 444 monthly transient stress periods representing the period 1979-2015. An initial steady-state stress period, in which the groundwater-flow equation had no storage component, represented mean annual inflows to and outflows from the aquifer and produced a solution that was used as the initial condition for subsequent transient stress periods. The numerical model was constructed in units of meters and days. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20185136)

In 2018 The U.S. Geological Survey, in cooperation with the U.S. Bureau of Reclamation and the Oklahoma Water Resources Board, published a calibrated numerical groundwater- flow model and associated model documentation report that evaluated the effects of potential groundwater withdrawals on groundwater flow and availability in the Rush Springs aquifer in western Oklahoma. The results of groundwater-availability scenarios run on the calibrated numerical groundwater-flow model could be used by the Oklahoma Water Resources Board to evaluate the maximum annual yield of groundwater from the Rush Springs aquifer in Oklahoma. A conceptual groundwater-flow model is a simplified description of the major inflow and outflow sources (hydrologic boundaries) of a groundwater-flow system as well as an accounting of the estimated mean flows from those sources (water budget) for a specified period of time. The conceptual model was necessary to provide constraints used in the construction and calibration of a scientifically defensible numerical groundwater-flow model that reasonably represents the groundwater-flow system. A finite-difference numerical groundwater-flow model of the Rush Springs aquifer was constructed by using MODFLOW-2005 with the Newton formulation solver (MODFLOW-NWT). Data inputs for each package were specified in machine-readable text files. The numerical model of the Rush Springs aquifer had 1,362 rows, 1,083 columns, about 554,000 active cells of 500 by 500 ft, and 3 convertible layers. The top layer (layer 1) represented the Permian-age Cloud Chief Formation. The Rush Springs aquifer is composed of Permian-age Whitehorse Group. The second layer (layer 2) represented the undifferentiated Quaternary-age alluvium and terrace deposits, as well as the upper 30 ft of the Whitehorse Group. The bottom layer (layer 3) represented the remainder of the Rush Springs Formation. The model active area was modified from Neel and others (2018). The numerical model was temporally discretized into 444 monthly transient stress periods representing the period 1979-2015. An initial steady-state stress period, in which the groundwater-flow equation had no storage component, represented mean annual inflows to and outflows from the aquifer and produced a solution that was used as the initial condition for subsequent transient stress periods. The numerical model was constructed in units of meters and days. This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20185136)

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 Boone and Roubidoux aquifers in northeastern Oklahoma by using MODFLOW-NWT (version 1.1.4) with the Newton formulation solver to simulate groundwater flow and account for the drying and rewetting of cells within the groundwater-flow model. The numerical groundwater-flow model was discretized into four layers consisting of 354 rows by 261 columns with a 2,000-feet by 2,000-feet cell size. The model layers were used to simulate the Western Interior Plains confining system, the Boone aquifer, the Ozark confining unit, and the Roubidoux aquifer. The model was temporally discretized into one steady-state stress period followed by 456 monthly transient stress periods spanning from January 1980 to December 2017. The steady-state stress period typically consisted of mean annual inputs from January 1980 to December 2017, but inputs from 1979 were included for some of the simulations.