A three-dimensional groundwater flow model was developed to simulate the effects of withdrawals on the groundwater-flow systems of five aquifers in and around Ocean County, New Jersey—the unconfined Kirkwood-Cohansey aquifer system and Vincentown aquifer, and three confined aquifers--the Rio Grande water-bearing zone, the Atlantic City 800-foot sand, and the Piney Point aquifer. A transient model was used to simulate conditions that represent no groundwater withdrawals, 2000–2003 groundwater withdrawals, and maximum-allocation groundwater withdrawals. Particle-tracking analysis, using results from two steady-state simulations, determine flow paths and travel times to near-shore wells screened in the unconfined Kirkwood-Cohansey aquifer system, the Rio Grande water-bearing zone, and the Atlantic City 800-foot sand. Sources of water to wells in both unconfined and confined aquifers and travel times based on particle-tracking analysis are used to assess the susceptibility of selected wells to saltwater intrusion from bay or ocean water. 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/sir20165035).

A three-dimensional groundwater-flow model (MODFLOW-2000 ) of the Kirkwood-Cohansey aquifer system, Rio Grande water-bearing zone, and Atlantic City 800-foot sand in the Great Egg Harbor and Mullica River Basins, N.J. was developed to simulate the effects of withdrawals on streamflow and groundwater supply. Increasing groundwater withdrawals from the unconfined Kirkwood Cohansey aquifer system is a major concern because of the potential for streamflow depletion and the resulting ecological effects on aquatic habitats, wetlands, and vernal ponds. In the confined Atlantic City 800-foot sand aquifer water levels have been steadily declining and most of the groundwater withdrawn from the Atlantic City 800-foot sand ultimately comes from the Kirkwood -Cohansey aquifer system. The groundwater flow model was used to simulate scenarios under three possible conditions: average 1998 to 2006 withdrawals (Average scenario), full-allocation withdrawals (Full Allocation scenario), and projected 2050-demand withdrawals (2050 Demand scenario). Three adjusted scenarios, variations of the Average, Full Allocation, and 2050 Demand scenarios, were simulated where withdrawals were modified in stages with the intent to successively eliminate or minimize the base-flow deficits. Monthly base-flow depletion criteria were determined using the NJDEP Low-Flow Margin method to estimate available water on an annual basis and if water-supply deficits exist. The model simulates monthly stress periods from 1998 through 2006. An existing regional model of the New Jersey Coastal Plain was revised to provide boundary conditions for the Great Egg Harbor and Mullica River Basin model (GEM). This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (http://pubs.usgs.gov/sir/2012/5187/).

A three-dimensional groundwater-flow model (MODFLOW-2000 ) of the Kirkwood-Cohansey aquifer system, Rio Grande water-bearing zone, and Atlantic City 800-foot sand in the Great Egg Harbor and Mullica River Basins, N.J. was developed to simulate the effects of withdrawals on streamflow and groundwater supply. Increasing groundwater withdrawals from the unconfined Kirkwood Cohansey aquifer system is a major concern because of the potential for streamflow depletion and the resulting ecological effects on aquatic habitats, wetlands, and vernal ponds. In the confined Atlantic City 800-foot sand aquifer water levels have been steadily declining and most of the groundwater withdrawn from the Atlantic City 800-foot sand ultimately comes from the Kirkwood -Cohansey aquifer system. The groundwater flow model was used to simulate scenarios under three possible conditions: average 1998 to 2006 withdrawals (Average scenario), full-allocation withdrawals (Full Allocation scenario), and projected 2050-demand withdrawals (2050 Demand scenario). Three adjusted scenarios, variations of the Average, Full Allocation, and 2050 Demand scenarios, were simulated where withdrawals were modified in stages with the intent to successively eliminate or minimize the base-flow deficits. Monthly base-flow depletion criteria were determined using the NJDEP Low-Flow Margin method to estimate available water on an annual basis and if water-supply deficits exist. The model simulates monthly stress periods from 1998 through 2006. An existing regional model of the New Jersey Coastal Plain was revised to provide boundary conditions for the Great Egg Harbor and Mullica River Basin model (GEM). This USGS data release contains all of the input and output files for the simulations described in the associated model documentation report (http://pubs.usgs.gov/sir/2012/5187/).

A previously developed groundwater-flow model of the Great Egg Harbor and Mullica River Basins, N.J. (https://doi.org/10.3133/sir20125187) by the U.S. Geological Survey (USGS) was used to analyze the effects on groundwater levels and stream base flow from possible changes in groundwater withdrawals and effluent infiltration in Winslow Township, Camden County, New Jersey. The Camden County Municipal Utilities Authority (CCMUA) infiltrated treated sewage effluent at their infiltration/percolation lagoons in Winslow Township, New Jersey, from 1985 to 2014. Increasing effluent volumes strained the capacity of the sewage-treatment plant and infiltration/percolation facility which closed in 2014. The treatment plant began pumping effluent from Winslow Township to the main CCMUA treatment facility which discharges treated effluent to the Delaware River. Eliminating infiltration of treated effluent in Winslow Township reduced groundwater recharge in the Great Egg Harbor River Basin and ultimately reducing groundwater discharge (base flow) to the Great Egg Harbor River. A study was conducted to determine the effects of eliminating the infiltration of treated effluent and reducing groundwater withdrawals from wells completed in the Kirkwood-Cohansey aquifer system on groundwater levels and base flow in the Great Egg Harbor River. The model simulates a baseline scenario with 2003-2007 withdrawals and five scenarios with different effluent infiltration conditions and 2008-2010 withdrawals using MODFLOW-2000 (version 1.18.01). This USGS data release contains all of the input and output files for the baseline scenario and five scenarios described in the associated report (https://doi.org/10.3133/sir20235002).

A previously developed groundwater-flow model of the Great Egg Harbor and Mullica River Basins, N.J. (https://doi.org/10.3133/sir20125187) by the U.S. Geological Survey (USGS) was used to analyze the effects on groundwater levels and stream base flow from possible changes in groundwater withdrawals and effluent infiltration in Winslow Township, Camden County, New Jersey. The Camden County Municipal Utilities Authority (CCMUA) infiltrated treated sewage effluent at their infiltration/percolation lagoons in Winslow Township, New Jersey, from 1985 to 2014. Increasing effluent volumes strained the capacity of the sewage-treatment plant and infiltration/percolation facility which closed in 2014. The treatment plant began pumping effluent from Winslow Township to the main CCMUA treatment facility which discharges treated effluent to the Delaware River. Eliminating infiltration of treated effluent in Winslow Township reduced groundwater recharge in the Great Egg Harbor River Basin and ultimately reducing groundwater discharge (base flow) to the Great Egg Harbor River. A study was conducted to determine the effects of eliminating the infiltration of treated effluent and reducing groundwater withdrawals from wells completed in the Kirkwood-Cohansey aquifer system on groundwater levels and base flow in the Great Egg Harbor River. The model simulates a baseline scenario with 2003-2007 withdrawals and five scenarios with different effluent infiltration conditions and 2008-2010 withdrawals using MODFLOW-2000 (version 1.18.01). This USGS data release contains all of the input and output files for the baseline scenario and five scenarios described in the associated report (https://doi.org/10.3133/sir20235002).

A third revision of the New Jersey Coastal Plain (NJCP) groundwater flow model, using MODFLOW-2005 (version 1.12.00), was completed to maintain the model’s usefulness for water-resource managment and development. The regional groundwater-flow model was initially developed for the U.S. Geological Survey (USGS) Regional Aquifer System Analysis (RASA) program. Periodic revision of the model is required as the result of changing hydrologic stresses, different and more complex water management needs, and increased knowledge of hydrologic conditions. The RASA model was initially constructed in the 1980’s as a quasi-3D model with 10 aquifers. The 9 intervening confining units were simulated using vertical leakage parameters at the aquifer contacts. The model was revised in the late 1990’s by (1) rediscretizing the model parameters with smaller grid spacing, (2) rediscretizing the stream cells for a better representation of streams, (3) using a spatially variable recharge rate based on studies conducted by the New Jersey Water Science Center since the model was initially developed, and (4) updating groundwater withdrawal data to 1998. For this study, the USGS, in cooperation with the New Jersey Department of Environmental Protection, again revised the model, updating the hydrogeologic framework, hydraulic parameters, and groundwater withdrawals. The revised 21-layer, fully three-dimensional, NJCP groundwater-flow model extends into Delaware and parts of Maryland and simulates 11 aquifers and 10 intervening confining units. The revisions include spatially and temporally variable recharge estimated using a Soil-Water-Balance (version 1.0.1) model; updated hydrologic parameters using UCODE_2014 (version 1.004) including the confining units in New Jersey and the hydrogeologic units in Maryland and Delaware; updated boundary flows from the North Atlantic Coastal Plain groundwater-flow model; groundwater withdrawals from 1980-2013 for the New Jersey Coastal Plain and from 1980-2010 for the modeled areas in Delaware and Maryland; and additional model layers to refine the simulated flow in Atlantic and Cape May Counties, New Jersey. The revisions to the model allows for (1) refined boundary flows for local models, (2) improved simulated interaction between water levels in southern New Jersey and withdrawals in Delaware, (3) simulation of the unconfined Kirkwood-Cohansey aquifer system and confined Rio Grande water-bearing zone, and (4) the ability to do particle tracking to determine regional sources of flow and times of travel. The groundwater flow model provides water managers with a tool to better understand the groundwater system of the New Jersey Coastal Plain, evaluate groundwater budget components, and make informed water-resource management decisions. 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/sir20235066).

A third revision of the New Jersey Coastal Plain (NJCP) groundwater flow model, using MODFLOW-2005 (version 1.12.00), was completed to maintain the model’s usefulness for water-resource managment and development. The regional groundwater-flow model was initially developed for the U.S. Geological Survey (USGS) Regional Aquifer System Analysis (RASA) program. Periodic revision of the model is required as the result of changing hydrologic stresses, different and more complex water management needs, and increased knowledge of hydrologic conditions. The RASA model was initially constructed in the 1980’s as a quasi-3D model with 10 aquifers. The 9 intervening confining units were simulated using vertical leakage parameters at the aquifer contacts. The model was revised in the late 1990’s by (1) rediscretizing the model parameters with smaller grid spacing, (2) rediscretizing the stream cells for a better representation of streams, (3) using a spatially variable recharge rate based on studies conducted by the New Jersey Water Science Center since the model was initially developed, and (4) updating groundwater withdrawal data to 1998. For this study, the USGS, in cooperation with the New Jersey Department of Environmental Protection, again revised the model, updating the hydrogeologic framework, hydraulic parameters, and groundwater withdrawals. The revised 21-layer, fully three-dimensional, NJCP groundwater-flow model extends into Delaware and parts of Maryland and simulates 11 aquifers and 10 intervening confining units. The revisions include spatially and temporally variable recharge estimated using a Soil-Water-Balance (version 1.0.1) model; updated hydrologic parameters using UCODE_2014 (version 1.004) including the confining units in New Jersey and the hydrogeologic units in Maryland and Delaware; updated boundary flows from the North Atlantic Coastal Plain groundwater-flow model; groundwater withdrawals from 1980-2013 for the New Jersey Coastal Plain and from 1980-2010 for the modeled areas in Delaware and Maryland; and additional model layers to refine the simulated flow in Atlantic and Cape May Counties, New Jersey. The revisions to the model allows for (1) refined boundary flows for local models, (2) improved simulated interaction between water levels in southern New Jersey and withdrawals in Delaware, (3) simulation of the unconfined Kirkwood-Cohansey aquifer system and confined Rio Grande water-bearing zone, and (4) the ability to do particle tracking to determine regional sources of flow and times of travel. The groundwater flow model provides water managers with a tool to better understand the groundwater system of the New Jersey Coastal Plain, evaluate groundwater budget components, and make informed water-resource management decisions. 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/sir20235066).

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-2005 with the SWI2 module, was developed to provide a better understanding of the geohydrology of the Kirkwood-Cohansey aquifer system in the vicinity of Edwin B. Forsythe National Wildlife Refuge, New Jersey. The model was used to evaluate the potential effects of three sea-level rise scenarios on the aquifer system. The model was calibrated to average 2005-15 hydrologic conditions. The model also simulated the movement of the freshwater-seawater interface for three sea-level rise scenarios.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/sir20175135).