The U.S. Geological Survey, in cooperation with the Town of Barnstable, Massachusetts, modified an existing numerical, steady-state regional MODFLOW-2005 groundwater-flow model to evaluate changes in water levels from a reference condition (2015) for nine pumping and wastewater return flow scenarios prepared by the Hyannis Water System. The three-dimensional, steady-state groundwater-flow model used to simulate water level changes is a modified and recalibrated version of an existing model that was used to simulate the potential effects of sea-level rise on groundwater levels of the Sagamore and Monomoy freshwater lenses of the Cape Cod aquifer (Walter and others, 2016) (https://doi.org/10.3133/sir20165058). Two modifications, (1) the addition of spatially variable natural recharge from precipitation, and (2) a revised representation of wastewater return-flow recharge to septic systems in the Town of Barnstable, were made to the existing regional groundwater-flow model for this study. The modified model was recalibrated to the same observations of heads and streamflows as those used in the original model. The modifications and results of the recalibration are described in the appendix of the associated scientific investigations report (https://doi.org/10.3133/sir20195121). The model is a mathematical representation of the groundwater-flow system. Several assumptions and limitations of the modeling approach are discussed in the report, as well as in the scientific investigations report describing the original model (https://doi.org/10.3133/sir20165058). This USGS data release contains all the input and output files for the simulations described in the associated scientific investigations report (https://doi.org/10.3133/sir20195121). The modified model supersedes the original model described by Walter and others (https://doi.org/10.3133/sir20165058).

The U.S. Geological Survey (USGS), in cooperation with the Town of Falmouth, used an existing groundwater flow model to simulate responses of the freshwater hydrologic system in Falmouth, Massachusetts to proposed wastewater-return-flow scenarios. The existing model is a steady-state, three-dimensional MODFLOW-2005 model of the Sagamore flow lens of the Cape Cod aquifer documented by Walter and others (2019). The existing model was updated with groundwater withdrawal and wastewater-return-flow data to represent average conditions for calendar years 2019 through 2023. The updated model was then used to simulate two wastewater-return-flow scenarios associated with the potential installation of an ocean outfall pipe in Falmouth, Massachusetts. This USGS data release contains the input and output files for the simulations described in the associated model documentation report (https://doi.org/10.3133/sir20255066). Associated Scientific Investigations Report: -------------------------------------- Goldstein, K.M.F., and McCobb, T.D., 2025, Simulated hydrologic responses to proposed wastewater-return-flow scenarios in Falmouth, Massachusetts: U.S. Geological Survey Scientific Investigations Report 2025-5066, 19 p., https://doi.org/10.3133/sir2025-5066. References: -------------------------------------- Walter, D.A., McCobb, T.D., and Fienen, M.N., 2019, Use of a numerical model to simulate the hydrologic system and transport of contaminants near Joint Base Cape Cod, Western Cape Cod, Massachusetts: U.S. Geological Survey Scientific Investigations Report 2019-5139, 98 p., https://doi.org/10.3133/sir20185139.

An existing, three-dimensional, transient groundwater-flow model of the Upper Charles River Basin, eastern Massachusetts, was modified to evaluate alternative groundwater-withdrawal scenarios on water levels in Kingsbury Pond. The pond is hydraulically connected to the groundwater-flow system, and water levels in the pond fluctuate in response to recharge to the aquifer from precipitation and wastewater return flows through septic systems, to withdrawals from the aquifer at nearby wells, and to precipitation directly on the pond surface. Concerns about the effects of groundwater withdrawals on water levels in the pond prompted an investigation by the U.S. Geological Survey (USGS) in cooperation with the Massachusetts Department of Environmental Protection to better understand the hydrology of Kingsbury Pond and its response to withdrawals. The goal of the study was to determine if withdrawals from wells in Franklin, Massachusetts, can be modified to simultaneously reduce the effect on water levels in the pond and yet meet the water-supply demands of the Town of Franklin. The model, which uses MODFLOW-2000, simulates flow within the surficial deposits and groundwater interactions with surface water in the basin. The model was modified for the study near Kingsbury Pond to improve representation of the hydrologic system near the pond. A groundwater-management model that links the groundwater-flow model with a mathematical-optimization method (referred to as the response-matrix method) was developed to evaluate the effects of three alternative groundwater-withdrawal scenarios for the Franklin public-water system on water levels in Kingsbury Pond. 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/sir20235083).

An existing, three-dimensional, transient groundwater-flow model of the Upper Charles River Basin, eastern Massachusetts, was modified to evaluate alternative groundwater-withdrawal scenarios on water levels in Kingsbury Pond. The pond is hydraulically connected to the groundwater-flow system, and water levels in the pond fluctuate in response to recharge to the aquifer from precipitation and wastewater return flows through septic systems, to withdrawals from the aquifer at nearby wells, and to precipitation directly on the pond surface. Concerns about the effects of groundwater withdrawals on water levels in the pond prompted an investigation by the U.S. Geological Survey (USGS) in cooperation with the Massachusetts Department of Environmental Protection to better understand the hydrology of Kingsbury Pond and its response to withdrawals. The goal of the study was to determine if withdrawals from wells in Franklin, Massachusetts, can be modified to simultaneously reduce the effect on water levels in the pond and yet meet the water-supply demands of the Town of Franklin. The model, which uses MODFLOW-2000, simulates flow within the surficial deposits and groundwater interactions with surface water in the basin. The model was modified for the study near Kingsbury Pond to improve representation of the hydrologic system near the pond. A groundwater-management model that links the groundwater-flow model with a mathematical-optimization method (referred to as the response-matrix method) was developed to evaluate the effects of three alternative groundwater-withdrawal scenarios for the Franklin public-water system on water levels in Kingsbury Pond. 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/sir20235083).

This model archive provides the necessary documentation of the numerical models developed for the Central Sands Lake study in central Wisconsin and will be included as a technical appendix (Appendix C) in the report to the Wisconsin State Legislature by the Wisconsin Department of Natural Resources (WDNR) in response to 2017 Wisconsin Act 10. This legislation directed DNR to determine whether existing and potential groundwater withdrawals are causing or are likely to cause significant reduction of mean seasonal water levels at Pleasant Lake, Long Lake, and Plainfield Lake (s. 281.34(7m)(2)(b), Wis. Stats.) in Waushara County, Wisconsin. To evaluate the potential hydrologic connection between groundwater withdrawals and the nearby study lakes, hydrologic models were created that focused on the lakes of interest and yet were large enough to cover a broad enough region to extend to the major hydrologic boundaries of the natural flow system. The areas near the lakes require finer-scale grid discretization (or spacing) to better represent the lakes and streams in the model, but also need to cover a large enough area to include the groundwater withdrawal locations that have the potential to cause reduction in water levels in the lakes. To accomplish these goals, three groundwater models were created: a regional model extending to major hydrologic boundaries; and two inset models, inheriting boundaries from the regional model but focused near the lakes. Each of the inset models, in turn, included a detailed area close to the lakes surrounded by an area at the same spatial scale as the regional model. To support WDNR in evaluating the connection between groundwater withdrawals and lake levels, a representative time period was required over which to compare land use with and without irrigated agriculture and for WDNR to evaluate potential lake stage and flux changes related to irrigated agriculture. WDNR chose the climate period of 1981-2018 to be representative of a typical period and provided two land use scenarios—one with no irrigated agriculture and one with assumed crop rotations similar to current conditions—to simulate with groundwater models to, then, compare lake responses with. As a result, simulations over this climate record are not intended to recreate the history of 1981-2018 because land use changed over that time. These runs are, instead, intended to provide a basis on which to compare land use with and without irrigation-related groundwater withdrawals based on the current arrangement of land use and a varied climatic record. Groundwater withdrawals focused on irrigated-agriculture-related water use because greater than 95% of groundwater withdrawal in the two inset models around the study lakes is for irrigated agriculture water use. The period of 2012-2018 was used for parameter estimation (synonymously referred to as “history matching”) for the groundwater models. This time period was chosen because it includes the most complete water use records to simulate groundwater withdrawals. History matching was performed using groundwater elevations, lake stages, and streamflow observations over the 2012-2018 time period and processed observations derived from those raw data. Climatic data were incorporated into the model using a soil-water balance approach. A soil water balance model (Westenbroek and others, 2021) was constructed at the scale of the regional groundwater model to both calculate recharge based on land use and climate, and in the long-term climate-period runs, to estimate water use required by irrigated agriculture to apply as well boundary conditions in the groundwater model in the absence of reported water use values over that period. The model archive presents all the inputs needed to run the models, the model software, information on history matching to estimate parameters of the model, model scenario files, and model outputs that the user should be able to recreate using the model files in this archive.

This model archive provides the necessary documentation of the numerical models developed for the Central Sands Lake study in central Wisconsin and will be included as a technical appendix (Appendix C) in the report to the Wisconsin State Legislature by the Wisconsin Department of Natural Resources (WDNR) in response to 2017 Wisconsin Act 10. This legislation directed DNR to determine whether existing and potential groundwater withdrawals are causing or are likely to cause significant reduction of mean seasonal water levels at Pleasant Lake, Long Lake, and Plainfield Lake (s. 281.34(7m)(2)(b), Wis. Stats.) in Waushara County, Wisconsin. To evaluate the potential hydrologic connection between groundwater withdrawals and the nearby study lakes, hydrologic models were created that focused on the lakes of interest and yet were large enough to cover a broad enough region to extend to the major hydrologic boundaries of the natural flow system. The areas near the lakes require finer-scale grid discretization (or spacing) to better represent the lakes and streams in the model, but also need to cover a large enough area to include the groundwater withdrawal locations that have the potential to cause reduction in water levels in the lakes. To accomplish these goals, three groundwater models were created: a regional model extending to major hydrologic boundaries; and two inset models, inheriting boundaries from the regional model but focused near the lakes. Each of the inset models, in turn, included a detailed area close to the lakes surrounded by an area at the same spatial scale as the regional model. To support WDNR in evaluating the connection between groundwater withdrawals and lake levels, a representative time period was required over which to compare land use with and without irrigated agriculture and for WDNR to evaluate potential lake stage and flux changes related to irrigated agriculture. WDNR chose the climate period of 1981-2018 to be representative of a typical period and provided two land use scenarios—one with no irrigated agriculture and one with assumed crop rotations similar to current conditions—to simulate with groundwater models to, then, compare lake responses with. As a result, simulations over this climate record are not intended to recreate the history of 1981-2018 because land use changed over that time. These runs are, instead, intended to provide a basis on which to compare land use with and without irrigation-related groundwater withdrawals based on the current arrangement of land use and a varied climatic record. Groundwater withdrawals focused on irrigated-agriculture-related water use because greater than 95% of groundwater withdrawal in the two inset models around the study lakes is for irrigated agriculture water use. The period of 2012-2018 was used for parameter estimation (synonymously referred to as “history matching”) for the groundwater models. This time period was chosen because it includes the most complete water use records to simulate groundwater withdrawals. History matching was performed using groundwater elevations, lake stages, and streamflow observations over the 2012-2018 time period and processed observations derived from those raw data. Climatic data were incorporated into the model using a soil-water balance approach. A soil water balance model (Westenbroek and others, 2021) was constructed at the scale of the regional groundwater model to both calculate recharge based on land use and climate, and in the long-term climate-period runs, to estimate water use required by irrigated agriculture to apply as well boundary conditions in the groundwater model in the absence of reported water use values over that period. The model archive presents all the inputs needed to run the models, the model software, information on history matching to estimate parameters of the model, model scenario files, and model outputs that the user should be able to recreate using the model files in this archive.

An existing three-dimensional model (MODFLOW-2000) by Petkewich and Campbell (2007) (https://pubs.usgs.gov/sir/2007/5126/) was updated to simulate six predictive water-management scenarios that were created to simulate potential changes in groundwater flow and groundwater-level conditions in the Mount Pleasant, South Carolina area. The model was recalibrated to conditions from 1900 to 2015. Simulations included six scenarios: (1) maximize Mount Pleasant Waterworks reverse-osmosis plant capacity by increasing groundwater withdrawals from 3.9 million gallons per day (Mgal/d) in 2015 to 8.6 Mgal/d from the Middendorf aquifer; (2) same as Scenario 1, but with the addition of a 0.5 Mgal/d supply well in the Middendorf aquifer near Moncks Corner, SC; (3) same as Scenario 1, but with the addition of a 1.5 Mgal/d supply well in the Middendorf aquifer near Moncks Corner, SC; (4) maximize Mount Pleasant Waterworks well capacity by increasing withdrawals from the Middendorf aquifer from 3.9 Mgal/d in 2015 to 10.2 Mgal/d (5) minimizing Mount Pleasant Waterworks surface-water purchase from the Charleston Water System by adding supply wells and increasing withdrawals from the Middendorf aquifer from 3.9 Mgal/d in 2015 to 12.2 Mgal/d; and (6) same as Scenario 1, but with the addition of quarterly model stress periods to simulate seasonal variations in the groundwater withdrawals. 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/sir20175128).

An existing three-dimensional model (MODFLOW-2000) by Petkewich and Campbell (2007) (https://pubs.usgs.gov/sir/2007/5126/) was updated to simulate six predictive water-management scenarios that were created to simulate potential changes in groundwater flow and groundwater-level conditions in the Mount Pleasant, South Carolina area. The model was recalibrated to conditions from 1900 to 2015. Simulations included six scenarios: (1) maximize Mount Pleasant Waterworks reverse-osmosis plant capacity by increasing groundwater withdrawals from 3.9 million gallons per day (Mgal/d) in 2015 to 8.6 Mgal/d from the Middendorf aquifer; (2) same as Scenario 1, but with the addition of a 0.5 Mgal/d supply well in the Middendorf aquifer near Moncks Corner, SC; (3) same as Scenario 1, but with the addition of a 1.5 Mgal/d supply well in the Middendorf aquifer near Moncks Corner, SC; (4) maximize Mount Pleasant Waterworks well capacity by increasing withdrawals from the Middendorf aquifer from 3.9 Mgal/d in 2015 to 10.2 Mgal/d (5) minimizing Mount Pleasant Waterworks surface-water purchase from the Charleston Water System by adding supply wells and increasing withdrawals from the Middendorf aquifer from 3.9 Mgal/d in 2015 to 12.2 Mgal/d; and (6) same as Scenario 1, but with the addition of quarterly model stress periods to simulate seasonal variations in the groundwater withdrawals. 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/sir20175128).

A three-dimensional groundwater flow model, MODFLOW-OWHM, was developed to provide a better understanding of the hydrogeology of the Lucerne Valley Groundwater Basin, California. The model was used to investigate the historical groundwater storage loss and subsidence associated with anthropogenic groundwater demands. The model was calibrated to 1942 through 2016 conditions. This USGS 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/sir20225048

A three-dimensional groundwater flow model, MODFLOW-OWHM, was developed to provide a better understanding of the hydrogeology of the Lucerne Valley Groundwater Basin, California. The model was used to investigate the historical groundwater storage loss and subsidence associated with anthropogenic groundwater demands. The model was calibrated to 1942 through 2016 conditions. This USGS 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/sir20225048