The previously developed three-dimensional groundwater flow model (MODFLOW2000) of the Denver Basin bedrock aquifer system and overlying alluvial aquifer (https://pubs.er.usgs.gov/publication/pp1770 and model archive https://doi.org/10.5066/F77W69PQ) was updated to provide quantitative estimates of groundwater flow conditions and provide a useful tool for managers to analyze temporal changes to the hydrologic system in response to changing climatic conditions and future groundwater development. The computer program ZONEBUDGET was used to calculate cell by cell water balances for the major components of the water budget for the Upper Big Sandy Designated Groundwater Basin alluvial aquifer. The original Denver Basin groundwater flow model was done as part of a large-scale regional groundwater availability study of the principal aquifers and represents regional time-varying (transient) conditions prior to 1880 through 2003. This model was updated to include updated well pumping data through 2016. This U.S. Geological Survey data release contains all of the input and output files for the simulation described in the associated model documentation report (https://doi.org/10.3133/sir20195049).

A three-dimensional groundwater flow model (MODFLOW2000) of the Denver Basin bedrock aquifer system and overlying alluvial aquifer was developed to provide quantitative estimates of groundwater flow conditions and provide a useful tool for managers to analyze temporal changes to the hydrologic system in response to changing climatic conditions and future groundwater development. In 2004, the U.S. Geological Survey (USGS) initiated large-scale regional studies to provide updated assessments of groundwater availability in important principal aquifers across the United States, including the Denver Basin. The Denver Basin groundwater flow model includes several enhancements over previous modeling efforts because of the availability of additional data, improved modeling capabilities, and advanced computer technology. Additional data available include updated geologic mapping, additional geophysical logs, water-level, streamflow, precipitation, and irrigation data collected since previous studies; and updated estimates of pumping from Denver Basin bedrock and alluvial aquifers. Modeling capabilities and computer technology also have advanced such that additional features, hydrologic processes, and numerical techniques are included in the current model that were not possible in previous models. The Denver Basin groundwater flow model represents regional time-varying (transient) conditions prior to 1880 through 2003. The model was calibrated by primarily adjusting hydraulic conductivity and recharge parameters until a best fit was obtained between observed and simulated transient hydraulic heads and flows using PEST. The calibrated model was used to estimate the hydrologic system response to two pumping scenarios for the period 2004 through 2053. This USGS data release contains all of the input and output files for the simulation and calibration described in the associated model documentation report (https://pubs.er.usgs.gov/publication/pp1770).

A three-dimensional groundwater flow model (MODFLOW2000) of the Denver Basin bedrock aquifer system and overlying alluvial aquifer was developed to provide quantitative estimates of groundwater flow conditions and provide a useful tool for managers to analyze temporal changes to the hydrologic system in response to changing climatic conditions and future groundwater development. In 2004, the U.S. Geological Survey (USGS) initiated large-scale regional studies to provide updated assessments of groundwater availability in important principal aquifers across the United States, including the Denver Basin. The Denver Basin groundwater flow model includes several enhancements over previous modeling efforts because of the availability of additional data, improved modeling capabilities, and advanced computer technology. Additional data available include updated geologic mapping, additional geophysical logs, water-level, streamflow, precipitation, and irrigation data collected since previous studies; and updated estimates of pumping from Denver Basin bedrock and alluvial aquifers. Modeling capabilities and computer technology also have advanced such that additional features, hydrologic processes, and numerical techniques are included in the current model that were not possible in previous models. The Denver Basin groundwater flow model represents regional time-varying (transient) conditions prior to 1880 through 2003. The model was calibrated by primarily adjusting hydraulic conductivity and recharge parameters until a best fit was obtained between observed and simulated transient hydraulic heads and flows using PEST. The calibrated model was used to estimate the hydrologic system response to two pumping scenarios for the period 2004 through 2053. This USGS data release contains all of the input and output files for the simulation and calibration described in the associated model documentation report (https://pubs.er.usgs.gov/publication/pp1770).

A three-dimensional groundwater flow model (MODFLOW200-FMP1_1) of the Central Valley in California was developed to aid water managers in understanding how water moves through the aquifer system, to predict water-supply scenarios, and to address issues related to water competition. The USGS Groundwater Resources Program made a detailed assessment of groundwater availability of the Central Valley aquifer system, which includes: (1) the present status of groundwater resources; (2) how these resources have changed over time; and (3) tools to assess system responses to stresses from future human uses and climate variability and change. This effort builds on previous investigations, such as the USGS Central Valley Regional Aquifer System and Analysis (CV-RASA) project and several other groundwater studies in the Valley completed by Federal, State and local agencies at differing scales. The principal product of this new assessment is a tool referred to as the Central Valley Hydrologic Model (CVHM) that accounts for integrated, variable water supply and demand, and simulates surface-water and groundwater-flow across the entire Central Valley system. The current model was extended to incorporate a slightly larger geographic area, has a finer spatial and temporal discretization, uses a more-detailed depiction of subsurface geology. In addition, the model utilizes a modified version of MODFLOW2000 (version 1.15.03) to include an updated and refined Farm Process (FMP1) to simulate groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis for April 1961 through September 2003. This USGS data release contains all of the input and output files for the simulation and calibration of the CVHM described in the associated model documentation report (https://pubs.er.usgs.gov/publication/pp1766).

A three-dimensional groundwater flow model (MODFLOW200-FMP1_1) of the Central Valley in California was developed to aid water managers in understanding how water moves through the aquifer system, to predict water-supply scenarios, and to address issues related to water competition. The USGS Groundwater Resources Program made a detailed assessment of groundwater availability of the Central Valley aquifer system, which includes: (1) the present status of groundwater resources; (2) how these resources have changed over time; and (3) tools to assess system responses to stresses from future human uses and climate variability and change. This effort builds on previous investigations, such as the USGS Central Valley Regional Aquifer System and Analysis (CV-RASA) project and several other groundwater studies in the Valley completed by Federal, State and local agencies at differing scales. The principal product of this new assessment is a tool referred to as the Central Valley Hydrologic Model (CVHM) that accounts for integrated, variable water supply and demand, and simulates surface-water and groundwater-flow across the entire Central Valley system. The current model was extended to incorporate a slightly larger geographic area, has a finer spatial and temporal discretization, uses a more-detailed depiction of subsurface geology. In addition, the model utilizes a modified version of MODFLOW2000 (version 1.15.03) to include an updated and refined Farm Process (FMP1) to simulate groundwater and surface-water flow, irrigated agriculture, land subsidence, and other key processes in the Central Valley on a monthly basis for April 1961 through September 2003. This USGS data release contains all of the input and output files for the simulation and calibration of the CVHM described in the associated model documentation report (https://pubs.er.usgs.gov/publication/pp1766).

The U.S. Geological Survey in cooperation with the Upper Arkansas Water Conservancy District, created a numerical groundwater-flow model for the Wet Mountain Valley alluvial aquifer using the finite-difference MODFLOW code with the Newton formulation solver. This numerical groundwater-flow model simulates water-budget components, groundwater and surface-water interactions, and evaluates the potential effects of aquifer storage and recovery through an added recharge simulation. The numerical model was spatially discretized into two layers with 261 rows and 133 columns of square cells at 250 meters on each side, for a total of 20,007 active cells. The model was rotated by 36 degrees to the northwest to align with the orientation of the valley and the assumed groundwater-flow directions. The numerical model was temporally discretized into 241 stress periods. The first stress period simulates a mean steady-state period, and the subsequent 240 stress periods were transient and simulate each month from 2000 to 2019. This U.S. Geological Survey data release includes all of the necessary files to simulate the Wet Mountain Valley alluvial aquifer and potential flow paths within it as described in the associated Scientific Investigations Report (https://doi.org/10.3133/sir20245105).

The U.S. Geological Survey in cooperation with the Upper Arkansas Water Conservancy District, created a numerical groundwater-flow model for the Wet Mountain Valley alluvial aquifer using the finite-difference MODFLOW code with the Newton formulation solver. This numerical groundwater-flow model simulates water-budget components, groundwater and surface-water interactions, and evaluates the potential effects of aquifer storage and recovery through an added recharge simulation. The numerical model was spatially discretized into two layers with 261 rows and 133 columns of square cells at 250 meters on each side, for a total of 20,007 active cells. The model was rotated by 36 degrees to the northwest to align with the orientation of the valley and the assumed groundwater-flow directions. The numerical model was temporally discretized into 241 stress periods. The first stress period simulates a mean steady-state period, and the subsequent 240 stress periods were transient and simulate each month from 2000 to 2019. This U.S. Geological Survey data release includes all of the necessary files to simulate the Wet Mountain Valley alluvial aquifer and potential flow paths within it as described in the associated Scientific Investigations Report (https://doi.org/10.3133/sir20245105).

The U.S. Geological Survey (USGS), in cooperation with the Air Force Civil Engineering Center, created a numerical groundwater-flow model for the Fountain Creek alluvial aquifer using the finite-difference MODFLOW code with the Newton formulation solver. This numerical groundwater-flow model simulates water-budget components, groundwater-flow directions, and groundwater-flow paths of the Fountain Creek alluvial aquifer. The numerical model was spatially discretized into a single layer with 291 rows and 254 columns of 200 by 200 feet size, and a total of 17,610 active cell. The numerical model was temporally discretized into 1 initial steady-state stress period representing the average conditions of the 240 monthly transient stress periods from 2000 to 2019. This USGS data release includes all the necessary files to simulate the Fountain Creek alluvial aquifer and potential flow paths within it as described in the associated USGS Scientific Investigations Report (https://doi.org/10.3133/sir20235119).

The U.S. Geological Survey (USGS), in cooperation with the Air Force Civil Engineering Center, created a numerical groundwater-flow model for the Fountain Creek alluvial aquifer using the finite-difference MODFLOW code with the Newton formulation solver. This numerical groundwater-flow model simulates water-budget components, groundwater-flow directions, and groundwater-flow paths of the Fountain Creek alluvial aquifer. The numerical model was spatially discretized into a single layer with 291 rows and 254 columns of 200 by 200 feet size, and a total of 17,610 active cell. The numerical model was temporally discretized into 1 initial steady-state stress period representing the average conditions of the 240 monthly transient stress periods from 2000 to 2019. This USGS data release includes all the necessary files to simulate the Fountain Creek alluvial aquifer and potential flow paths within it as described in the associated USGS Scientific Investigations Report (https://doi.org/10.3133/sir20235119).

A new version of previously published steady-state numerical groundwater flow models of the Great Basin carbonate and alluvial aquifer system (GBCAAS), and was developed in conjunction with U.S. Geological Survey (USGS) studies in Parowan, Pine, and Wah Wah Valleys, Utah. This version of the model is considered to be GBCAAS v. 3.0 and supersedes previous versions. This model added 15 transient calibration stress periods and 14 projection stress periods, aquifer storage properties, historical withdrawals in Parowan Valley, and observations of water-level changes in Parowan Valley to the previous steady-state versions. Recharge in Parowan Valley and withdrawal from wells in Parowan Valley and two nearby wells in Cedar City Valley vary for each calibration stress period representing conditions from March 1940 to November 2013. Stresses, including recharge, are the same in each stress period as in the steady-state stress period for all areas outside of Parowan Valley. This data release contains one calibration simulation and one projection simulation. The model is calibrated to transient conditions only in Parowan Valley. Simulated storage properties outside of Parowan Valley are set the same as the Parowan Valley properties and should not be considered calibrated. The projection simulation was used to estimate that reducing withdrawals in Parowan Valley from 35,000 to about 22,000 acre-feet per year should stabilize groundwater levels in the valley if recharge varies as it did from about 1950 to 2012 and that withdrawals of 15,000 acre-feet per year from Pine Valley and 6,500 acre-feet per year from Wah Wah Valley could ultimately (long-term steady-state) cause water-level declines of about 1,900 feet near the withdrawal wells and more than 5 feet over about 10,500 square miles. 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/sir20175072). This data release also contains source code needed to run the models. Model files presented in this data release were modified from an existing, calibrated, steady-state model of the Great Basin carbonate and alluvial aquifer system. SIR 2014-5213 (https://pubs.usgs.gov/sir/2014/5213/) and SIR 2017-5011 (https://doi.org/10.3133/sir20175011) document the construction and calibration of the previous versions of this model. Modifications that were made to the input files and discussion of model results are documented in SIR2017-5072 (https://doi.org/10.3133/sir20175072), which is associated with this data release. The model consists of a parent and a child model and must be run using MODFLOW-LGR. The child model is far removed from the area considered for this project, but is being kept with the model so that one model version exists of the Great Basin carbonate and alluvial aquifer system that incorporates all refinements and improvements. The model files documented in this data release should be used instead of previous versions.