Prepared in cooperation with the Capital Area Groundwater Conservation Commission; the 

Louisiana Department of Transportation and Development, Public Works and Water 

Resources Division; and the City of Baton Rouge and Parish of East Baton Rouge

Simulation of Groundwater Flow in the “1,500-Foot” Sand

and “2,000-Foot” Sand and Movement of Saltwater in the 

“2,000-Foot” Sand of the Baton Rouge Area, Louisiana 

By Charles E. Heywood and Jason M. Griffith

Open-File Report 2013–1153

U.S. Department of the Interior

U.S. Geological Survey
ii

U.S. Department of the Interior

Sally Jewell, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2013 

For more information on the USGS—the Federal source for science about the Earth,

it’s natural and living resources, natural hazards, and the environment—visit 

http://www.usgs.gov or call 1–888–ASK–USGS

For an overview of USGS information products, including maps, imagery, and publications,

visit http://www.usgs.gov/pubprod

To order this and other USGS information products, visit http://store.usgs.gov

Suggested citation:

Heywood, C.E., and Griffith, J.M., 2013, Simulation of groundwater flow in the “1,500-foot” sand and “2,000-foot” 

sand and movement of saltwater in the “2,000-foot” sand of the Baton Rouge area, Louisiana: U.S. Geological 

Survey Open-File Report 2013-1153, 79 p., http://pubs.usgs.gov/of/2013/1153/. 

Any use of trade, product, or firm names is for descriptive purposes only and does not imply 

endorsement by the U.S. Government. 

Although this report is in the public domain, permission must be secured from the individual 

copyright owners to reproduce any copyrighted material contained within this report.
iii

Acknowledgments

The authors would like to thank the many people who have contributed substantially to a better 

understanding of the hydrogeology and saltwater encroachment in the Baton Rouge area in southeastern 

Louisiana. Don C. Dial, Anthony J. Duplechin, Zahir “Bo” Bolourchi, and other members of the Capital 

Area Ground Water Conservation Commission provided guidance and assistance throughout this 

investigation.

Contents

Acknowledgments......................................................................................................................................................iii

Conversion Factors................................................................................................................................................... vii

Abbreviations ........................................................................................................................................................... viii

Abstract ......................................................................................................................................................................... 1

Introduction.................................................................................................................................................................... 2

Purpose and Scope.................................................................................................................................................... 3

Previous Investigations .............................................................................................................................................. 3

Study Area Description .............................................................................................................................................. 4

Horizontal Datum and Projection Systems ............................................................................................................. 4

Hydrogeology................................................................................................................................................................. 4

Baton Rouge Fault ..................................................................................................................................................... 5

Occurrence and Movement of Saltwater.................................................................................................................... 6

Hydrogeologic Framework ......................................................................................................................................... 6

Groundwater Withdrawals.............................................................................................................................................. 7

Simulation of Groundwater Flow and Movement of Saltwater ....................................................................................... 8

Conceptual Model for Saltwater Transport................................................................................................................. 9

Equations of Groundwater Flow and Transport.......................................................................................................... 9

Spatial Discretization................................................................................................................................................ 10

Internal Flow Package.............................................................................................................................................. 11

Horizontal-Flow Boundaries ................................................................................................................................. 11

Temporal Discretization ........................................................................................................................................... 12

Boundary Conditions................................................................................................................................................ 12

No-Flow Boundaries............................................................................................................................................. 12

Specified Head Boundaries.................................................................................................................................. 12

Head-Dependent Flux Boundaries ....................................................................................................................... 13

Specified-Concentration Boundaries and Initial Conditions .................................................................................. 13

Hydraulic-Property Distribution................................................................................................................................. 14

Horizontal Interpolation of Hydraulic Conductivity ................................................................................................ 14

Transport Properties............................................................................................................................................. 15

Model Calibration......................................................................................................................................................... 15

Calibration Dataset................................................................................................................................................... 15

Water-Level Observations.................................................................................................................................... 16

Wellbore-Flow Observation .................................................................................................................................. 16

Concentration Observations................................................................................................................................. 16

Water-Level Observation Errors ........................................................................................................................... 17

Weights ................................................................................................................................................................ 17
iv

Calibration Assessment ........................................................................................................................................... 17

Estimated Parameter Values................................................................................................................................ 18

Parameter Sensitivities......................................................................................................................................... 18

Residual Plot ........................................................................................................................................................ 18

Simulated Groundwater Conditions ............................................................................................................................. 19

Simulated Water Levels ........................................................................................................................................... 19

Simulated Connector-Well Flow Rate ...................................................................................................................... 20

Simulated Water Budget .......................................................................................................................................... 21

Simulated Concentrations ........................................................................................................................................ 21

Limitations and Appropriate Use of the Model ............................................................................................................. 22

Hypothetical Groundwater Management Scenarios..................................................................................................... 22

Scenario 1: Continued Groundwater Withdrawals at 2007 Rates ............................................................................ 23

Scenario 2: Reduction of Groundwater Withdrawals from the “1,500-foot” Sand..................................................... 23

Scenario 3: Scavenger Well Withdrawal from the Base of “2,000-foot” Sand .......................................................... 24

Scenario 4: Reduction of Groundwater Withdrawals from the “2,000-foot” Sand in the Baton Rouge Industrial 

District...................................................................................................................................................................... 25

Scenario 5: Cessation of Groundwater Withdrawals from the “2,000-foot” Sand in the Baton Rouge Industrial 

District...................................................................................................................................................................... 25

Summary ..................................................................................................................................................................... 26

Selected References ................................................................................................................................................... 28

Figures

(At back of report.)

Figure 1. Map showing location of the study area, the Baton Rouge Fault, geophysical-control wells, and 

simulated groundwater-withdrawal wells in southeastern Louisiana and southwestern Mississippi.

Figure 2. Hydrogeologic section A-A’ in East Baton Rouge and East and West Feliciana Parishes, southeastern 

Louisiana.

Figure 3. Map showing simulated altitude of the top of the “1,500-foot” sand of the Baton Rouge area in 

southeastern Louisiana and southwestern Mississippi.

Figure 4. Map showing simulated thickness of the “1,500-foot” sand of the Baton Rouge area in southeastern 

Louisiana and southwestern Mississippi. 

Figure 5. Map showing simulated altitude of the top of the “2,000-foot” sand of the Baton Rouge area in 

southeastern Louisiana and southwestern Mississippi. 

Figure 6. Map showing simulated thickness of the “2,000-foot” sand of the Baton Rouge area in southeastern 

Louisiana and southwestern Mississippi. 

Figure 7. Conceptual offset of hydrogeologic units at faults in the Baton Rouge area, southeastern Louisiana. 

Figure 8. Graph showing estimated withdrawals from the Baton Rouge sands, 1940–2007. 

Figure 9. Map showing the model finite-difference grid and locations of the horizontal flow barriers in the “2,000-

foot” sand of the Baton Rouge area and simulated groundwater-withdrawal wells in southeastern Louisiana and 

southwestern Mississippi. 
v

Figure 10. Map showing the finite-difference grid and locations of horizontal flow barriers; simulated 

groundwater-withdrawal wells, and water-level observation wells in the "1,000-foot,” “1,200-foot," "1,700-foot," 

"2,400-foot," and "2,800-foot" sands of the Baton Rouge area in the detailed model area in southeastern Louisiana.

Figure 11. North-south cross section along model column 24 showing aquifers, confining units, and finitedifference discretization.

Figure 12. Map showing pilot point locations and the simulated horizontal hydraulic-conductivity distribution 

within: A, the “1,500-foot” sand; B, the “2,000-foot” sand of the Baton Rouge area in the detailed model area in 

southeastern Louisiana.

Figure 13. Graph showing residuals as a function of simulated water level altitudes for the “2,000-foot” sand 

and all other simulated aquifers. Residuals are calculated by subtracting simulated water-level altitudes from 

observed water-level altitudes.

Figure 14. Map showing simulated steady-state water-levels within the “1,500-foot” sand of the Baton Rouge 

area representing predevelopment conditions before 1940 in southeastern Louisiana and southwestern Mississippi.

Figure 15. Map showing simulated steady-state water-levels within the “2,000-foot” sand of the Baton Rouge 

area representing predevelopment conditions before 1940 in southeastern Louisiana and southwestern Mississippi.

Figure 16. Maps showing simulated 2007 water levels within the “1,500-foot” sand of the Baton Rouge area in: 

A, southeastern Louisiana and southwestern Mississippi; and B, the detailed model area in southeastern Louisiana.

Figure 17. Maps showing simulated 2007 water levels within the “2,000-foot” sand of the Baton Rouge area in: 

A, southeastern Louisiana and southwestern Mississippi; and B, the detailed model area in southeastern Louisiana.

Figure 18. Graphs showing simulated and observed water levels within the “1,000-foot” and “1,200-foot” sands 

of the Baton Rouge area in southeastern Louisiana.

Figure 19. Graphs showing simulated and observed water levels within the “1,500-foot” sand of the Baton 

Rouge area in southeastern Louisiana.

Figure 20. Graphs showing simulated and observed water levels within the “1,700-foot” sand of the Baton 

Rouge area in southeastern Louisiana.

Figure 21. Graphs showing simulated and observed water levels within the “2,000-foot” sand of the Baton 

Rouge area in southeastern Louisiana.

Figure 22. Graphs showing simulated and observed water levels within the “2,400-foot” sand of the Baton 

Rouge area in southeastern Louisiana.

Figure 23. Graph showing simulated and observed water levels within the “2,800-foot” sand of the Baton 

Rouge area in southeastern Louisiana.

Figure 24. Graph showing simulated groundwater withdrawals and flows from storage and specified-head 

boundaries.

Figure 25. Graph showing simulated and observed chloride concentrations at observation wells within the 

“2,000-foot” sand of the Baton Rouge area in southeastern Louisiana.

Figure 26. Map showing simulated 2007 water levels and chloride concentrations at the base of the “2,000-

foot” sand of the Baton Rouge area in the detailed model area in southeastern Louisiana.

Figure 27. Map showing predicted 2047 water levels within the “1,500-foot” sand of the Baton Rouge area in 

the detailed model area in southeastern Louisiana after continued pumping at 2007 rates.
vi

Figure 28. Map showing predicted 2047 water levels and chloride concentrations at the base of the “2,000-foot” 

sand of the Baton Rouge area in the detailed model area in southeastern Louisiana after continued pumping at 

2007 rates.

Figure 29. Graphs showing predicted chloride concentrations at the base of the “2,000-foot” sand after 

continued pumping at 2007 rates (scenario 1), scavenger wells (scenario 3), 3.6 Mgal/d (million gallon per day) 

reduction of industrial-district withdrawals (scenario 4), and cessation of industrial-district withdrawals from the 

“2,000-foot” sand (scenario 5) for: A, well EB-1028; B, well EB-1150; C, well EB-630; D, well EB-781; E, well EB807B; and F, hypothetical well EB-X.

Figure 30. Map showing predicted 2047 water levels in the “1,500-foot” sand of the Baton Rouge area in the 

detailed model area in southeastern Louisiana following cessation of pumping from selected industrial wells in the 

“1,500-foot” and “1,700-foot” sands after 2007.

Figure 31. Map showing predicted 2047 water levels and chloride concentrations at the base of the “2,000-foot” 

sand of the Baton Rouge area in the detailed model area in southeastern Louisiana after 40 years of pumping at a 

rate of 2 million gallons per day from a simulated scavenger well located in model row 57 and column 26.

Figure 32. Map showing predicted 2047 water levels and chloride concentrations at the base of the “2,000-foot” 

sand of the Baton Rouge area in the detailed model area in southeastern Louisiana after 40 years of pumping at a 

rate of 2 million gallons per day from a simulated scavenger well located in model row 68 and column 30.

Figure 33. Map showing predicted 2047 water levels and chloride concentrations at the base of the “2,000-foot” 

sand of the Baton Rouge area in the detailed model area in southeastern Louisiana after a 3.6 million gallon per 

day reduction in pumping (from 2007 rates) at selected wells in the Baton Rouge industrial district.

Figure 34. Map showing predicted 2047 water levels and chloride concentrations at the base of the “2,000-foot” 

sand of the Baton Rouge area in the detailed model area in southeastern Louisiana following cessation of pumping 

from the “2,000-foot” sand in the Baton Rouge industrial district after 2007.

Tables

(At back of report.)

Table 1. Groundwater withdrawals (min millon gallons per day) in the Baton Rouge area, Louisiana, by parish 

and principal use, 2010.

Table 2. Aquifers and aquifer systems in southern Mississippi and southeastern Louisiana and corresponding 

model layers.

Table 3. Time discretization summary.

Table 4. Parameter values and sensitivities for the calibrated groundwater-flow model.

Table 5. Simulated steady-state and transient flow rates.

Table 6. Simulated plume areas and chloride concentrations.
vii

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square foot (ft2) 0.09290 square meter (m2)

square mile (mi2) 2.590 square kilometer (km2) 

acre 4,047 square meter (m2)

Volume

gallon (gal) 0.003785 cubic meter (m3) 

cubic foot (ft3) 0.02832 cubic meter (m3) 

Flow rate

cubic foot per day (ft3/d) 0.02832 cubic meter per day (m3/d)

gallon per minute (gal/min) 0.06309 liter per second (L/s)

gallon per day (gal/d) 0.003785 cubic meter per day (m3/d)

million gallons per day (Mgal/d) 0.04381 cubic meter per second (m3/s)

Density

pound per cubic foot (lb/ft3) 16.02 kilogram per cubic meter 

(kg/m3)

pound per cubic foot (lb/ft3) 0.01602 gram per cubic centimeter 

(g/cm3)

Hydraulic conductivity

foot per day (ft/d) 0.3048 meter per day (m/d)

Transmissivity*

foot squared per day (ft2/d) 0.09290 meter squared per day (m2/d) 

Temperature in degrees Fahrenheit (°F) may be converted to degrees Celsius (°C) as follows:

°C=(°F-32)/1.8

Vertical coordinate information is referenced to the National Geodetic Vertical Datum of 1929 (NGVD 29). 

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

Altitude, as used in this report, refers to distance above the vertical datum.

Concentrations of chemical constituents in water are given in milligrams per liter (mg/L).
viii

Abbreviations 

City-Parish City of Baton Rouge and Parish of East Baton Rouge 

Commission Capital Area Groundwater Conservation Commission 

DOTD Louisiana Department of Transportation and Development 

DNR Louisiana Department of Natural Resources

FHB Flow and Head Boundary package

GIS Geographic information system

HOB Head Observation Package

HUF Hydrogeologic-Unit Flow package 

IMT Integrated Mass Transport package 

Mgal/d million gallons per day

mg/L milligram per liter

MNW2 Multi-Node Well package 

NWIS National Water Information System

RASA Regional Aquifer System Analysis

TVD Total Variation Diminishing scheme

USGS U.S. Geological Survey 

VDF Variable-Density Flow package

[M] mass dimension

[L] length dimension 

[T] time dimension
1

Simulation of Groundwater Flow in the “1,500-foot” Sand

and “2,000-foot” Sand and Movement of Saltwater in the 

“2,000-foot” Sand of the Baton Rouge Area, Louisiana

By Charles E. Heywood and Jason M. Griffith

Abstract

Groundwater withdrawals have caused saltwater to encroach into freshwater-bearing aquifers 

beneath Baton Rouge, Louisiana. Groundwater investigations in the 1960s identified a freshwatersaltwater interface located at the Baton Rouge Fault, across which abrupt changes in water levels occur. 

Aquifers south of the fault generally contain saltwater, and aquifers north of the fault contain 

freshwater, though limited saltwater encroachment has been detected within 7 of the 10 aquifers north of 

the fault. The 10 aquifers beneath the Baton Rouge area, which includes East and West Baton Rouge 

Parishes, Pointe Coupee Parish, and East and West Feliciana Parishes, provided about 167 million 

gallons per day (Mgal/day) for public supply and industrial use in 2010. Groundwater withdrawals from 

an aquifer that is 2,000-feet (ft) deep in East Baton Rouge Parish (the “2,000-foot” sand of the Baton 

Rouge area) have caused water-level drawdown up to 356 ft and induced saltwater movement northward 

across the fault. Groundwater withdrawals from the “2,000-foot” sand averaged 23.9 Mgal/d during 

2010. Saltwater encroachment threatens wells that are located about 3 miles north of the fault, where 

industrial withdrawals account for about 66 percent of the water withdrawn from the “2,000-foot” sand 

in East Baton Rouge Parish. Constant and variable-density groundwater models were developed with 

the MODFLOW and SEAWAT groundwater modeling codes to evaluate strategies to control saltwater 

migration, including changes in the distribution of groundwater withdrawals and installation of 

“scavenger” wells to intercept saltwater before it reaches existing production wells. 

Five hypothetical scenarios simulated the effects of different groundwater withdrawal options on 

groundwater levels within the “1,500-foot” sand and the “2,000-foot” sand and the transport of 

saltwater within the “2,000-foot” sand. Scenario 1 is considered a base case for comparison to the other 

four scenarios and simulates continuation of 2007 reported groundwater withdrawals. Scenario 2 

simulates discontinuation of withdrawals from seven selected industrial wells located in the northwest 

corner of East Baton Rouge Parish, and water levels within the “1,500-foot” sand were predicted to be 

about 15 to 20 ft higher under this withdrawal scenario than under scenario 1. Scenario 3 simulates the 

effects of a scavenger well, which withdraws water from the base of the “2,000-foot” sand at a rate of 2 

Mgal/d, at two possible locations on water levels and concentrations within the “2,000-foot” sand. In 

comparison to the concentrations simulated in scenario 1, operation of the scavenger well in the 

locations specified in scenario 3 reduces the chloride concentrations at all existing chloride-observation 

well locations. Scenario 4 simulates a 3.6 Mgal/d reduction in total groundwater withdrawals from 

selected wells screened in the “2,000-foot” sand that are located in the Baton Rouge industrial district. 

For scenario 4, the median and mean plume concentrations are slightly lower than scenario 1. Scenario 5 

simulates the effect of total cessation of groundwater withdrawals from the “2,000-foot” sand in the 
2

industrial district. The simulated chloride-concentration distribution in scenario 5 reflects the change in 

groundwater flow direction. Although some saltwater would continue to cross the Baton Rouge Fault 

and encroach toward municipal supply wells, further encroachment toward the industrial district would 

be abated.

Introduction

Fresh groundwater is a valuable resource in southeastern Louisiana and the five-parish Baton 

Rouge capital area (subsequently referred to as the “Baton Rouge area”), which includes East and West 

Baton Rouge, Pointe Coupee, and East and West Feliciana Parishes. In the Baton Rouge area, fresh 

groundwater in most aquifers is soft sodium bicarbonate water with a dissolved-solids concentration of 

about 200 milligrams per liter (mg/L) (Meyer and Turcan, 1955), and requires little treatment for 

potable use or industrial purposes (Stuart and others, 1994). Groundwater withdrawals in the Baton 

Rouge area since the 1940s have lowered water levels in the “2000-ft” sand as much as 356 feet (ft), and 

altered groundwater-flow directions in most of the 10 underlying freshwater-bearing aquifers. During

2010, about 196 million gallons per day (Mgal/d) of groundwater was withdrawn (table 1) in the Baton 

Rouge area (Sargent, 2011), mostly in East Baton Rouge Parish. Groundwater usage in 2010 was 

primarily for public supply and industry, which consumed about 94 Mgal/d and 73 Mgal/d, respectively. 

Withdrawals from the aquifers that are 1500-ft-deep and 2,000-ft-deep (termed the "1,500-foot” sand

and "2,000-foot” sand) in the Baton Rouge area were about 19.9 Mgal/d and 23.9 Mgal/d, or 10.2 

percent and 12.2 percent of the total withdrawals, respectively (P. Sargent, USGS, written commun., 

2013). The drawdown of groundwater levels has caused saltwater to encroach into areas previously 

containing freshwater near Baton Rouge, and saltwater encroachment has been detected in seven

aquifers, including the “1,500-foot” sand and the “2,000-foot” sand in East Baton Rouge Parish (Meyer 

and Turcan, 1955; Morgan, 1961; Tomaszewski, 1996; Lovelace, 2007). Within the “2,000-foot” sand, 

saltwater threatens industrial withdrawals from wells which account for about 66 percent of the 

withdrawals from the “2,000-foot” sand in East Baton Rouge Parish. 

 Water planners and managers need additional knowledge of the effects of groundwater 

withdrawals on the rate and pathways of saltwater migration and to assess possible management 

strategies that could control further saltwater encroachment in the Baton Rouge area. In response to this 

concern, the U.S. Geological Survey (USGS), in cooperation with the Capital Area Ground Water 

Conservation Commission (Commission), Louisiana Department of Transportation and Development 

(DOTD) Water Resources Office, and the City of Baton Rouge and Parish of East Baton Rouge (CityParish), developed the groundwater-flow and saltwater-transport model of the Southern Hills regional 

aquifer system that is documented in this report. The model simulates the effects of reported 

groundwater withdrawals on groundwater flow in the “1,500-foot” sand and “2,000-foot” sand, and the 

movement of saltwater in the “2,000-foot” sand northward from the Baton Rouge Fault in East Baton 

Rouge Parish. The model simulates historical conditions (prior to 2008) and five possible future 

pumping scenarios and can be used to evaluate possible strategies to mitigate saltwater encroachment in 

the “2,000-foot” sand in the Baton Rouge area. The model provides a tool for evaluation of the need, 

effectiveness, and possible locations of additional pumping, injection, or observation wells that may 

either mitigate or be used to monitor saltwater encroachment. The model also provides a framework for 

future studies of groundwater flow and saltwater encroachment in other aquifers within the 

groundwater-flow system. It could also facilitate study of possible saltwater-encroachment mitigation 

strategies and increase understanding of saltwater movement in similar hydrogeologic settings. A digital 

archive of the groundwater model is on file at the USGS office in Baton Rouge. 
3

Purpose and Scope

This report documents the hydrogeologic framework of the Southern Hills regional aquifer 

system in southeastern Louisiana and in southwestern Mississippi, the hydraulic properties of the 

aquifer system, groundwater-withdrawal rates, and the development and calibration of a groundwaterflow and saltwater-transport model that simulates groundwater flow in the “1,500-foot” sand and 

“2,000-foot” sand and migration of saltwater within the “2,000-foot” sand in the Baton Rouge area. The 

simulated effects of groundwater withdrawals on water levels and flow directions in the “2,000-foot” 

sand and “1,500-foot” sand and on the movement of saltwater in the “2,000-foot” sand are described. 

Five future scenarios are discussed that represent the effects of continued groundwater withdrawals and 

possible strategies to mitigate saltwater encroachment in the “2,000-foot” sand beneath the city of Baton 

Rouge. 

The model domain encompasses an area of about 6,600 square miles (mi2) in southeastern 

Louisiana and southwestern Mississippi; however, its primary focus is on the “1,500-foot” sand and 

“2,000-foot” sand in a 25-mi2 area in Baton Rouge where large groundwater withdrawals have occurred 

and where saltwater encroachment is of concern. Simulation of regional groundwater flow through all 

hydrogeologic units in the Southern Hills aquifer system helped assure reasonable simulated results 

within the primary area of concern. 

Previous Investigations

Several previous reports included background data on the geologic, hydraulic, and water-quality 

characteristics of freshwater-bearing aquifers in the Baton Rouge area (Meyer and Turcan, 1955; 

Morgan, 1961). Morgan and Winner (1964) documented known areas of saltwater in aquifers 

underlying East and West Baton Rouge Parishes and estimated the rates of saltwater movement toward 

areas of large groundwater withdrawals in the industrial district and toward public-supply pumping 

stations. Whiteman (1979) included a detailed discussion of saltwater encroachment in the “600-foot” 

sand and “1,500-foot” sand and discussions of saltwater in other aquifers. Whiteman (1979) also 

documented the existence of the east-west trending Baton Rouge Fault as a leaky hydrologic barrier that 

limits northward movement of saltwater in aquifers in the Baton Rouge area. Buono (1983) described 

the freshwater-bearing aquifers in the northern parishes of southeastern Louisiana (including those in 

the Baton Rouge area) and the up-dip equivalent aquifers in Mississippi as an interdependent system, 

which he named the “Southern Hills regional aquifer system” (table 1). Griffith (2003) presented 

hydrogeologic cross sections of the freshwater aquifers in southeastern Louisiana, which he described as 

a sequence of complexly interbedded, interconnected, lenticular (lens shaped), alluvial, freshwaterbearing, clayey, sandy, and graveliferous strata. Morgan and Winner (1964), Whitman (1979), 

Tomaszewski (1996), and Lovelace (2007) documented the occurrence of saltwater and increasing 

chloride concentrations within various aquifers in the Baton Rouge area.

In 1975, the USGS began a cooperative program with the DOTD and the Commission to analyze 

groundwater flow by using groundwater models of aquifers in the Baton Rouge area, including the 

"400-foot” sand, "600-foot” sand, "1,500-foot” sand, "1,700-foot” sand, and “2,000-foot” sand in the 

Baton Rouge area (Torak and Whiteman, 1982; Huntzinger and others, 1985; Kuniansky, 1989; Halford 

and Lovelace, 1994). Under the USGS regional aquifer-system analysis (RASA) program, the 

hydrogeologic framework, groundwater chemistry, and regional flow patterns in the freshwater aquifers 

along the northern Gulf of Mexico Coast in Louisiana and parts of Texas and Mississippi were 

described, and groundwater flow models were used to simulate regional flow patterns (Martin and 

Whiteman, 1990). 
4

Study Area Description

The study area encompasses about 6,600 mi2 in southeastern Louisiana and southwestern 

Mississippi (fig. 1). The study area extends southward from about 25 miles (mi) north of the Mississippi 

state line to Gonzales, La., in the south and eastward from Breaux Bridge, La., in the west to Hammond, 

La., in the east. In southeastern Louisiana, all or parts of Ascension, Assumption, Avoyelles, Concordia, 

East and West Baton Rouge, East and West Feliciana, Iberville, Livingston, Pointe Coupee, St. Helena, 

St. Martin, St. Landry, and Tangipahoa Parishes are in the study area. In Mississippi, all or parts of 

Adams, Amite, Franklin, Lincoln, Pike, and Wilkinson Counties are in the study area. 

The terrain in the study area varies from forested rolling hills in the north to flat lowlands and 

swamps in the south. The Mississippi River valley dominates the setting near the western and southern 

boundaries of the study area. Land-surface altitudes range from 0 ft to more than 450 ft (Calhoun and 

Frois, 1997). The climate is subtropical, warm, and temperate with an average annual temperature of 

68 oF (20 oC) and an average annual rainfall of 61 inches (National Oceanic and Atmospheric 

Administration, 1995). 

About 1 million people live within the study area, with largest populations in the Baton Rouge 

metropolitan area (U.S. Census Bureau, 2010). All of the public water supplied in the Baton Rouge area 

in 2010 was groundwater (Sargent, 2011). Several industrial facilities, primarily located along the 

Mississippi River, also utilize the groundwater resources in the study area (table 1). In addition, 

groundwater supplies about 84 percent of agricultural water use in the study area (Sargent, 2011). 

Horizontal Datum and Projection Systems

The geographic coordinates of database features, such as well-head locations, and geographic 

information system (GIS) data used in the model are referenced to the North America Datum of 1983 

(NAD83). To represent model-cell areas accurately, polygon and point GIS coverages of the model 

finite-difference cells and nodes, created with the program MODELGRID (Kernodle and Philip, 1988), 

were generated in a Lambert Conformal Conic projection system. The model finite-difference grid 

columns are oriented north-south in the Lambert Conformal Conic projection system. These GIS 

coverages were subsequently projected into the Universal Transverse Mercator (UTM) zone 15 

coordinate system that was used for GIS coverages of wells, the hydrogeologic framework, and water 

levels. Consequently, the model finite difference grid appears slightly rotated in the UTM projection 

displayed in the map figures in this report. Projection and coordinate system details are contained in a 

file in the digital model archive. 

Hydrogeology

Aquifers containing freshwater in the Baton Rouge area are generally part of the Southern Hills 

regional aquifer system and include the Mississippi River alluvial aquifer, the shallow sands of the 

Baton Rouge area, the upland terrace aquifer, the “400-foot” sand, “600-foot” sand, “800-foot” sand, 

“1,000-foot” sand, “1,200-foot” sand, “1,500-foot” sand, “1,700-foot” sand, “2,000-foot” sand, “2,400-

foot “sand, and “2,800-foot” sand of the Baton Rouge area and the Catahoula aquifer (Meyer and 

Turcan, 1955; Morgan, 1961; Buono, 1983; Griffith, 2003). The Mississippi River alluvial aquifer and 

the shallow sands of the Baton Rouge area are the shallowest aquifers in the Baton Rouge area. Deeper 

aquifers in the Baton Rouge area include aquifers that are named for their depth of occurrence in the 

Baton Rouge industrial district (table 2; fig. 2) and the Catahoula aquifer. Aquifers in the Baton Rouge 

area have been correlated with aquifers in southern Mississippi and in Louisiana parishes east of the 

study area. The aquifers also have been grouped based on correlative units in southwestern and central 
5

Louisiana into the Chicot equivalent, Evangeline equivalent, Jasper equivalent and Catahoula equivalent 

aquifer systems (Stuart and others, 1994). Although the Catahoula aquifer contains freshwater in some 

areas, it is generally too deep and contains too much saltwater to be an economically viable water 

resource in the Baton Rouge area (Griffith, 2003). 

Freshwater-bearing aquifers in the Baton Rouge area range in composition from very fine to 

coarse sand with some pea-to-cobble-sized gravel (Griffith, 2003) and are sufficiently permeable to 

yield economically substantial quantities of water to wells (Bates and Jackson, 1984). The aquifers are 

separated by confining units composed of material ranging from solid clay to sandy and silty clay that 

limit vertical groundwater flow. The freshwater aquifers and intervening confining units in the Baton 

Rouge area, together with the up-dip equivalent units in southwestern Mississippi, form a thickening 

wedge that dips to the south and southwest toward the Gulf of Mexico and Mississippi River alluvial 

valley (fig. 2). The confining units generally pinch out northward, and deeper aquifers coalesce with 

overlying surficial aquifers.

The average annual precipitation over the study area is 54 to 60 inches, and precipitation in the 

northern part of the study area (fig. 1) and farther north in Mississippi is the primary source of recharge

to the aquifer system. Because the aquifers are interconnected, precipitation that infiltrates through the 

shallow, surficial aquifers located in recharge areas flows southward into deeper aquifers. Kuniansky 

(1989) estimated a range from 0.2 to 4.6 inches per year (in/yr) for deep regional aquifer recharge. 

Groundwater velocities range from a few tens of feet per year to several hundreds of feet per year 

(Buono, 1983). 

The “1,500-foot” sand and “2,000-foot” sand, like other freshwater aquifers in the study area, 

generally dip and thicken to the south and consist of single or multiple 65- to 95-ft thick intervals of fine 

to medium sand and 100 to 300 ft of medium sand. Where the aquifers contain multiple sand intervals, 

the intervals are separated by clays. The “1,500-foot” sand is about 1,500 ft deep beneath Baton Rouge 

north of the Baton Rouge Fault, but is displaced deeper south of the fault (fig. 3). The “1,500-foot” sand 

is continuous throughout the study area except in parts of Avoyelles, East and West Baton Rouge, 

Livingston, and Point Coupee Parishes and in most of Mississippi (fig. 4). The “2,000-foot” sand is 

about 2,000 ft deep beneath Baton Rouge north of the Baton Rouge Fault, but is also displaced deeper 

south of the fault (fig. 5). The “2,000-foot” sand is continuous throughout the study area (fig. 6). The 

location and thickness of the aquifers in Mississippi are based on the correlation of the “1,500-foot” 

sand and “2,000-ft” sand in the Baton Rouge area with up-dip units in southwestern Mississippi (Meyer 

and Turcan, 1955; Morgan, 1961; Newcome, 1975; Huntzinger and others, 1985; Griffith, 2003.) 

Baton Rouge Fault

The Baton Rouge Fault extends across the southern part of the study area (fig. 2) and is part of a 

series of east-west trending faults in southern Louisiana (Murray, 1961; Hanor, 1982; Griffith, 2003). 

The location of the Baton Rouge Fault was documented in the 1960s and 1970s after the importance of 

the fault as a barrier to groundwater flow in the aquifers in the Baton Rouge area became apparent 

(Meyer and Rollo, 1965; Whiteman, 1979). McCulloh (1991) mapped the detailed location of the 

surface expression of faults through East Baton Rouge Parish. Within the study area, the Baton Rouge 

Fault dips to the south at angles between about 65 degrees and 70 degrees (Durham and Peeples, 1956; 

Smith and Kazmann, 1978; Whiteman, 1979; Roland and others, 1981; Hanor, 1982; McCulloh, 1991; 

Griffith, 2003, 2006). 

Sediment deformation and displacement of sedimentary layers across the fault reduce the 

hydraulic connections between aquifers, thereby impeding horizontal groundwater flow, which causes 

substantial changes in both water levels and water quality across the fault. The displacement of aquifers 
6

across the Baton Rouge Fault ranges from about 20 ft near the ground surface to about 300 ft at altitudes 

of -1,600 to -3,000 ft (fig. 2). In the Baton Rouge area the displacement of the “1,500-foot” sand and 

“2,000-foot” sand at the Baton Rouge Fault are about 235 and 250 ft, respectively (Durham and Peeples, 

1956; Meyer and Rollo, 1965; Smith and Kazmann, 1978; Whiteman, 1979; Roland and others, 1981; 

Hanor, 1982; McCulloh, 1991; Griffith, 2003, 2006). 

Occurrence and Movement of Saltwater

Groundwater investigations conducted during the 1960s identified a freshwater-saltwater 

interface located near the Baton Rouge Fault (Morgan and Winner, 1964; Rollo, 1969). Prior to 

groundwater development in the 1940s, freshwater flowed from recharge areas in Mississippi southward 

toward the fault, then upward to where it discharged at springs. This groundwater flow pattern caused 

aquifers north of the fault to generally contain freshwater, whereas they may contain saltwater south of 

the fault. In the Baton Rouge area, the base of freshwater is between about 1,100 and 2,600 ft deeper on 

the north side of the fault than it is on the south side of the fault. The altitude of the base of freshwater 

ranges between about -1,500 ft and -3,500 ft north of the fault, and between -200 and -1,000 ft south of 

the fault (Smoot, 1988; Griffith, 2003). Aquifer tests conducted across the fault in the vicinity of Baton 

Rouge have indicated that the fault acts as a leaky barrier that impedes groundwater flow (Whiteman, 

1979). 

Large groundwater withdrawals north of the fault in Baton Rouge, primarily for public supply 

and industrial use, have lowered water levels and created gradients conducive to the movement of 

saltwater from the south side of the fault into previously freshwater areas north of the fault (Whiteman, 

1979; Tomaszewski, 1996). Except in the deeper "2,800-foot” sand and Catahoula aquifers, most 

saltwater currently north of the fault moved in response to the groundwater withdrawals in the Baton 

Rouge area. If groundwater withdrawals in the Baton Rouge area continue at rates similar to the 

historical rates, saltwater encroachment will probably continue to occur (Tomaszewski, 1996). 

Based on historical chloride-concentration data collected through 2005, saltwater and water 

containing chloride concentrations above background levels (10 mg/L or less) have been detected in all 

aquifers in the Baton Rouge area except the “800-foot” sand and “1,700-foot” sand (Lovelace, 2007). 

Analyses of chloride-concentration measurements collected from wells prior to 1992 indicated that 

saltwater encroachment had occurred in the “600-foot” sand, “800-foot” sand, “1,000-foot” sand, 

“1,500-foot” sand, and “2,000-foot” sand (Morgan and Winner, 1964; Whiteman, 1979; Tomaszewski, 

1996). Chloride concentration data collected from 1993 to 2003 indicated that chloride concentrations 

increased in the “1,000-foot” sand, “1,200-foot” sand, “1,500-foot” sand, “2,000-foot” sand, “2,400-

foot” sand, and “2,800-foot” sand (Lovelace, 2007). Chloride concentrations measured during 2004 to 

2005 exceeded background levels in one or more water samples from wells in East and West Baton 

Rouge Parishes north of the fault screened in the “600-foot” sand, “1,000-foot” sand, “1,200-foot” sand, 

“1,500-foot” sand, “1,700-foot” sand, “2,000-foot” sand, “2,400-foot” sand, and “2,800-foot” sand. 

Comparison of the 2004–5 data with historical data indicated that chloride concentrations north of the 

Baton Rouge Fault were increasing in all of those aquifers except the “1,700-foot’ sand (Lovelace, 

2007). Within the “2,000-foot” sand, chloride concentrations of about 3,500 mg/L have been measured 

3 miles east of the Mississippi River and about 500 feet north of the Baton Rouge Fault in observation 

well EB-781. 

Hydrogeologic Framework

A three-dimensional hydrogeologic framework was constructed to delineate the extents and 

thicknesses of aquifers and confining units in the study area. The hydrogeologic framework represents 
7

the entire sequence of aquifers and confining units in the Southern Hills regional aquifer system above 

the Catahoula-equivalent aquifer system (table1). The Catahoula-equivalent aquifer system was omitted 

from the framework because in the study area it contains mostly saltwater and is little used and few 

geophysical logs were available to delineate the extent and thickness of the aquifers in the system. The 

hydrogeologic framework defines the top altitudes and thicknesses of the hydrogeologic units in the 

groundwater model documented in this report. Although the groundwater model was primarily 

developed to address concerns about declining groundwater levels in the “1,500-foot” sand and “2,000-

foot” sand and saltwater encroachment in the “2,000-foot” sand, simulating groundwater flow in 

overlying and underlying aquifers improved the simulation of water-levels in the “1,500-foot” sand and 

“2,000-foot” sand aquifers. 

The top of the hydrogeologic framework is the ground surface and the base is the bottom of the 

“2,800-foot” sand. The aquifers and confining units are represented by 22 layers, numbered from the top 

toward the bottom (table 1). Layers 1, 3, 5, 7, 9–18, 20, and 22 make up the aquifer layers. Layers 2, 4, 

6, 8, 19, and 21 make up confining units that separate the aquifer layers. Layers 1 and 3 represent

multiple aquifers that have similar hydraulic characteristics and are likely interconnected. Layer 1 

represents the Mississippi River alluvial aquifer, shallow sands, upland terrace aquifer, and the “400-

foot” sand, “600-foot” sand, and “800-foot” sand. Layer 3 includes the “1,000-foot” sand and “1,200-

foot” sand. The “2,000-foot” sand is represented by 10 layers numbered 9 through 18. 

The location and thickness of aquifer and confining-unit layers in the hydrogeologic framework 

were specified based on about 3,200 lithologic contacts (altitudes of interpreted sand-clay interfaces)

interpreted from 192 borehole resistance, spontaneous potential, resistivity, nuclear, and drillers’ 

lithologic logs, and the previous work of Griffith (2003). Generally, aquifer and confining units less 

than 10-ft thick were not represented by discrete layers in the hydrogeologic framework.

Raster arrays of the top altitudes and thicknesses of all hydrogeologic-framework layers were 

constructed with the VIEWLOG interpolation tool (Viewlog Systems, 2004). Hydrogeologic contacts 

interpreted from logs outside the study area were used to specify the hydrogeologic-unit altitudes along 

the boundary of the study area. The hydrogeologic-unit top altitudes interpolated with VIEWLOG were 

manually smoothed in areas where data were unavailable (generally near the margin of the study area). 

Contour maps (figs. 3, 4, 5, and 6) illustrate the top altitudes and thicknesses of the hydrogeologicframework layers that represent the “1,500-foot” sand and the “2,000-foot” sand. 

The location and correlation of hydrogeologic units near the Baton Rouge Fault in the study area 

is uncertain (Griffith, 2003), and the apparent displacement of units may be due to differences in 

sediment deposition on either side of the fault (Smith, 1979). By using previous reports (Durham and 

Peeples, 1956; Murray, 1961; Winner and others, 1968; Rollo, 1969; Whiteman, 1979; Smith, 1979; 

Hanor, 1982; Smoot, 1988; McCulloh, 1991; Griffith, 2003, 2006) and the lithologic contacts, separate 

representations of hydrogeologic-unit layer top altitudes and thicknesses were generated for areas north 

and south of the Baton Rouge Fault. The separate north and south representations for each layer were 

linked at the fault to form a single representation for each layer so that differences in layer-top altitudes

across the Baton Rouge Fault represent the vertical fault displacement (fig. 7).

Groundwater Withdrawals

Withdrawals from 605 wells in Louisiana for the period of 1940 to 2007 were compiled from the 

digital databases and paper records of the USGS and the Commission. Most of these withdrawal records 

were reported by personnel at public supply and industrial facilities. 

Withdrawal rates for wells or facilities inventoried on a 5-year basis from 1960 to 2005 were 

obtained from USGS water-use records. Sporadic annual withdrawal data from 1940 to 1975 for some 
8

facilities in the Baton Rouge area also were obtained from USGS water-use records. Annual withdrawal 

rates from wells in East and West Baton Rouge, East and West Feliciana, and Pointe Coupe Parishes 

from 1975 to 2007 were obtained from the Commission water-use database. Annual withdrawal rates 

from about 1988 to 2007 for facilities that withdraw an average of 1 Mgal/d or greater and are located in 

other parishes in the study area were obtained from USGS water-use records. 

Where only facility-specific withdrawals were available, well-specific rates were estimated by 

disaggregating the total withdrawal rate reported for the facility. Generally the disaggregated wellspecific withdrawal rates were estimated by evenly distributing the withdrawals reported for each 

facility among the active wells at the respective facility. Well registration, construction, and plugging or 

abandonment data from USGS, DOTD, Commission, and Louisiana Department of Natural Resources 

(DNR) databases were used to determine when specific wells were in use at the facilities where facilityspecific withdrawals were reported. For some wells with intermittent data, annual withdrawals were 

estimated or interpolated to complete their pumpage records. In some cases, facilities were contacted to 

verify pumping rates and well activity during different periods. 

Well-construction data including the borehole, screen, and casing diameters; screen intervals; 

pump depth; location; and land-surface altitude were obtained from USGS and state databases. Missing 

or inadequate information was estimated or adjusted by using ancillary information from topographic 

maps, well logs, the specifications of other nearby wells or wells with identical ownership, well 

schedules, and thickness data from the hydrogeologic framework. Some wells with inadequate wellconstruction information and probable withdrawal rates less than 0.01 Mgal/d were omitted. Wells with 

screen-interval records corresponding to confining-unit intervals in the hydrogeologic framework were 

assumed to be screened in aquifers and were assigned to the appropriate adjacent sand layer. 

A graph of the withdrawals from aquifers in the Baton Rouge area, also known as the “Baton 

Rouge sands” (fig. 8), illustrates both increased total withdrawals and the withdrawal from deeper 

aquifers through time. Until the early 1950s, groundwater withdrawals were principally from the “400-

foot” sand and the “600-foot” sand. Since that time, deeper aquifers such as the “1,200-foot” sand, 

“1,500-foot” sand, “2,000-foot” sand, “2,400-foot” sand, and “2,800-foot” sand have increasingly 

supplied the majority of groundwater in the Baton Rouge area. 

Simulation of Groundwater Flow and Movement of Saltwater

The modeling strategy was to initially construct a constant-density groundwater flow model and 

calibrate the groundwater-flow model parameters to observed water levels throughout the aquifer 

system. Subsequently, the simulation of saltwater transport with a variable-density version of the 

groundwater flow model was accomplished. Calibration of simulated concentrations to chloride 

concentrations observed in the Baton Rouge area required minor modification of some flow-model 

parameters and estimation of parameters that represented effective porosity and aquifer dispersivities. 

The highest observed chloride concentration north of the Baton Rouge Fault within the “2,000-foot” 

sand has been 3,500 mg/L, implying that groundwater at that location has a density of about 62.71 

pounds per cubic foot (lb/ft3

), which is about 0.45 percent greater than freshwater. Although the density 

of localized areas of brackish to saline groundwater (chloride concentration from 1,000 to 10,000 mg/L) 

may sufficiently contrast with adjacent fresher groundwater to affect flow in some areas, such as 

adjacent to the Baton Rouge Fault, density contrasts over larger areas are not thought to substantially

affect regional groundwater flow. Because the constant-density groundwater-flow code MODFLOW2005 (Harbaugh, 2005) can apportion specified pumpage withdrawals among multiple aquifers 

penetrated by a single well, which is important for simulating transient groundwater flow in the Baton 

Rouge area, it was used during the groundwater-flow model calibration process. After the groundwater 
9

flow model had been calibrated, the optimal set of flow parameters and computed well fluxes were 

imported into the variable-density code SEAWAT, which enabled simulation of saltwater transport. 

High concentrations of salt (sodium chloride) increase groundwater density and can affect the 

patterns and rates of groundwater flow if the density varies spatially. Although most chloride 

concentrations in the “2,000-foot” sand north of the Baton Rouge Fault are less than several hundred 

milligrams per liter, which is too low to substantially increase groundwater density, concentrations up to 

3,500 mg/L near the north side of the fault have been observed and are likely higher in observed 

locations closer to the source of the salt. The effect of density contrasts on groundwater flow was

simulated with the variable-density finite-difference code SEAWAT (Langevin and others, 2003), 

which integrates MODFLOW-2000 (Harbaugh and others, 2000) with MT3DMS (Zheng and Wang, 

1999), a code that simulates solute transport. Because chloride is a conservative solute, chemical 

reactions were not simulated in the SEAWAT transport model. Temperature gradients within the 

Southern Hills aquifer system north of the Baton Rouge Fault are not substantial and are not known to 

affect groundwater flow within the “1,500-foot” sand and “2,000-foot” sand. The groundwater system 

was therefore modeled as isothermal, and temperature effects on groundwater density and viscosity 

were not simulated.

The model-input for SEAWAT and MODFLOW-2005 is generally similar, but the multi-node 

well package, MNW2 (Konikow and others, 2009), was not available with SEAWAT. Because the 

apportionment of withdrawals among aquifers from wells tapping multiple aquifers was important for 

groundwater-flow model calibration, the MODFLOW-2005 code was used during the parameterestimation process. After the flow-model parameters had been optimized, an equivalent WEL package 

(Harbaugh and others, 2000) input was generated with MNW2 by using the parameter values optimized 

for the MODFLOW-2005 simulation. This computed WEL Package input was subsequently used to 

specify layer-variable groundwater fluxes for each withdrawal well in the SEAWAT simulation. 

Conceptual Model for Saltwater Transport

Groundwater north of the Baton Rouge Fault is assumed to have been fresh prior to groundwater 

development. Groundwater entering the model domain in areas north of the Baton Rouge Fault is 

considered “fresh” with a zero salt concentration. Because sediments south of the Baton Rouge Fault are 

displaced downward, the source of saltwater south of the Baton Rouge Fault is likely within the “1,700-

foot” sand, where its altitude is similar to that of the “2,000-foot” sand north of the fault. Although 

chloride concentrations south of the Baton Rouge Fault have been observed to vary spatially and some 

areas of freshwater are known to occur, a simple representation of the saltwater source is preferred to 

model transport north of the fault. This source was specified within the finite-difference cells adjacent to 

the south side of the fault that connect to the “2,000-foot” sand on the north side of the fault. As

groundwater withdrawals cause aquifer water levels to decline north of the Baton Rouge Fault, higher 

pressure saltwater south of the fault seeps northward across the hydraulically resistive fault. 

Equations of Groundwater Flow and Transport

Whereas MODFLOW-2005 solves the constant-density groundwater flow equation (Harbaugh, 

2005), the SEAWAT-2000 (Langevin and others, 2003) code iteratively solves equations that represent 

variable-density groundwater flow and advective-dispersive mass transport. These equations are 

succinctly presented below, and the interested reader may refer to the referenced model-code 

documentation for further details. 
10

Groundwater systems without significant chemical reactions or temperature gradients are 

governed by equations for variable-density flow: 

( ) t

C

Ct

P

qq s Sp ∂

∂

∂

ρ∂ θ+

∂

∂ ρ=ρ+ρ⋅∇−  (1)

and mass transport: 

 ( ) Cs

qs Cq CD

t

C

θ  −



 





θ

⋅∇−∇⋅∇=

∂

∂ 

 

(2)

where: ∇ is the gradient operator, ρ is fluid density [ML-3], q



is specific discharge [LT-1], ρ is source or 

sink fluid density [ML-3], qs is flow rate per unit volume representing sources or sinks [T-1], Sp is 

specific storage in pressure terms [M-1LT2

], P is fluid pressure [ML-1T-2], t is time [T], θ is effective 

porosity, C is solute concentration [ML-3], D is the dispersion coefficient [L2T-1], and Cs is source or 

sink solute concentration [ML-3]. These groundwater flow and transport equations are coupled by the 

specific discharge ( q



) and concentration ( C ) terms. The dependence of fluid density on concentration 

can be approximated by a linear equation of state: 

C

C f ∂

∂ρ =ρ ρ + (3)

where ρf is the density of freshwater. The SEAWAT-2000 (Langevin and others, 2003) code iteratively 

solves finite-difference versions of these variable-density flow and mass transport equations for every 

transport time step, thereby coupling the flow and transport equations. Because this solute-transport 

problem was advection-dominated, the advection-dispersion (equation 2) was numerically solved with 

the third-order total-variation-diminishing (TVD) scheme to reduce numerical dispersion (Zheng and 

Wang, 1999). 

Spatial Discretization

The three-dimensional finite-difference groundwater model grid (fig. 9) was designed with 

variable grid-cell spacing to (1) provide sufficient spatial resolution in a 25-mi2area (the detailed model 

area) where significant saltwater migration either has occurred or could occur in the future (fig. 10), (2) 

locate model boundaries sufficiently far from the detailed model area to minimize the effects of 

boundary conditions on simulated heads in the area, and (3) limit execution times to enable numerous 

model simulations to be conducted during calibration through parameter estimation. The total area 

encompassed by the model domain is 6,529.23 mi2 and contains of 158,950 active finite difference cells. 

The areas encompassed by the finite-difference cells range from 2.5x105 ft2

 (5.74 acres) in the detailed 

model area to a maximum of 3x109 ft2

 (68,870 acres) at the northwest corner of the model domain. 

The variable grid spacing creates large finite-difference-cell aspect ratio, or differences in the

north-south versus east-west dimensions, in some areas of the model grid. Although numerical 

inaccuracies can occur in such areas (de Marsily, 1986), they are located in areas of the model grid 

where high computational accuracy is not required. 

The model grid consists of 22 variable-thickness layers, each of which is a rectangular array 

containing 85 rows and 85 columns of finite-difference cells. For a subset of the model grid, 50 rows by 

55 columns, a horizontal grid spacing of 500 ft, and vertical layer spacing of about 20 ft within the 

“2,000-foot” sand were specified within the 25-mi2 detailed model area based on preliminary 

simulations along two-dimensional cross-sections through the Baton Rouge area. Transport of saltwater 

was only simulated within the detailed model area to limit model execution times.

The altitude of the top of each model layer on the north side of the Baton Rouge Fault was 

assigned the altitude of the top of hydrogeologic-framework unit represented by the layer (table 2). 
11

South of the Baton Rouge Fault, the altitudes of the top of each finite-difference layer do not correspond 

to the tops of hydrogeologic-framework units and are constant along columns of finite-difference cells 

(that is, in the north-south direction). This geometry facilitated simulation of flow across the Baton 

Rouge Fault and is explained in further detail in the “Internal Flow Package” section. The north-south 

cross-sectional view of the model grid (fig. 11) along column 24 illustrates the variable thickness and 

“pinching out” of hydrogeologic units north of the Baton Rouge Fault, offset of hydrogeologic units at 

the fault, and the discordance between hydrogeologic units and finite-difference cells south of the fault. 

In comparison to numerical solution of the transient groundwater-flow equation, numerical 

solution of the transient solute-transport equation is computationally intensive. It is therefore generally 

desirable to limit the size of the numerical solute-transport problem when possible. Because simulation 

of saltwater encroachment is needed in only a small portion of the flow-model domain, a subset of the 

groundwater-flow model grid was identified for simulation of solute transport. This solute-transport 

domain is the previously described “detailed model area” that has a 500-ft cell spacing (fig. 10). Within 

this area, the solute transport equation was numerically solved in all model layers but was calibrated 

only for model layers 9 through 18, which correspond to the “2,000-foot” sand on the north side of the 

Baton Rouge Fault. 

Internal Flow Package

Offsets of hydrogeologic units at the Baton Rouge Fault may enable flow from stratigraphically 

younger hydrogeologic units south of the fault into stratigraphically older and horizontally juxtaposed 

units north of the fault. This flow between hydrogeologic units was simulated by using the 

Hydrogeologic-Unit Flow Package (HUF) (Anderman and Hill, 2000), which represents the thickness of 

hydrogeologic units independently from that of the model finite-difference-grid-cell layers and

calculates storage and intercell conductance terms for each cell from the hydraulic-property distributions 

assigned to individual hydrogeologic units present within that cell. In this model, the altitudes of the 

finite-difference layers correspond to the tops and bottoms of the aquifers and intervening confining 

units defined in the hydrogeologic framework only for the portion of the model domain north of the 

Baton Rouge Fault (fig. 1). South of the Baton Rouge Fault, the finite-difference-layer altitudes within 

each model-grid column are “flat,” with altitudes equal to those at the simulated fault location. The 

finite-difference layers do not correspond to specific hydrogeologic units south of the Baton Rouge 

Fault. Because of this lack of correspondence, different hydrogeologic units are contained within each 

finite-difference layer on the north versus south sides of the fault, which allows simulated flow and 

transport within finite-difference layers between different aquifers that are horizontally juxtaposed at the 

fault. For example, within model finite-difference layers 9 through 18, the “1,700-foot” sand on the 

south side of the fault is connected to the “2,000-foot” sand on the north side of the fault. 

Horizontal-Flow Boundaries

The resistance to groundwater flow at the Baton Rouge Fault as a consequence of sediment 

deformation and displacement of sedimentary layers was simulated with horizontal flow barriers (HFB) 

(Hsieh and Freckleton, 1993), which were specified along the vertical faces of cells closest to the fault. 

The decrease of each HFB to the conductance between adjacent model cells is specified with a 

“hydraulic characteristic” that is dimensionally equivalent to the hydraulic conductivity of the fault zone 

(in the direction perpendicular to the fault plane) divided by the width of the fault zone. HFBs were 

defined for all model layers that simulated aquifers except model layer 1. 

Because the Baton Rouge Fault plane dips to the south at 65 to 70 degrees, the fault dip was 

represented by offsetting the fault to the south in deeper framework layers. In layers 2 through 7 the 
12

fault is represented 500 ft south of the representation for layer 1 and where indicated in figure 1, 

whereas in layers 8 through 22 the fault is offset 1,000 ft south of the representation for layer 1. 

Temporal Discretization

Because groundwater withdrawals from the Southern Hills aquifer system were relatively minor 

prior to about 1940, a single steady-state stress period was used to simulate predevelopment conditions 

in the groundwater flow system (table 3). Sixty-eight annual stress periods simulated the time from 

January 1, 1940 through December 31, 2007. Each stress period was discretized into 5 time steps that 

geometrically increase in duration by a factor of 1.4, such that the first time step of each stress period 

simulated about 33 days. Hypothetical scenarios used four 10-year transient stress periods representing 

January 1, 2008 through December 31, 2047, each of which were discretized into 11 time steps that also

geometrically increase in duration by a factor of 1.4, such that the first time step simulated about 37 

days. The geometric progression of increasing time-step length provided good temporal discretization 

for simulation of transient changes in groundwater levels. In the solute-transport simulations, flow time 

steps are further subdivided into transport time steps (table 3). The number of transport time steps was

computed internally on the basis of the flow velocity to maintain numerical stability and varied with the 

specified effective porosity and boundary conditions, such as specified groundwater withdrawal rates. 

Smaller transport time steps are required as the flow velocity increases.

Boundary Conditions

Boundary conditions were specified at the boundaries of the groundwater flow system and 

within the model domain where they simulate groundwater-withdrawal wells. Three types of boundary 

conditions were specified for the groundwater-flow model: no-flow, specified head, and head-dependent 

flux. Constant-concentration boundaries were also specified at the lateral boundaries of the solutetransport model. 

No-Flow Boundaries

The north, east, and west sides and the top 21 layers of the southern side of the groundwaterflow model domain (fig. 9) are located where negligible groundwater flow is assumed to enter or exit 

the model domain and were accordingly considered no-flow boundaries. The southernmost row of the 

lowest model layer (row 85, layer 22) contains a specified-head boundary. The model-domain perimeter 

was located sufficiently far from the Baton Rouge area to minimize any effect on simulated water levels 

in that area from possible inaccuracy of the no-flow boundary-condition specification. The bottom 

model boundary at the base of layer 22 is also no-flow and corresponds to the top of a confining unit 

located above the Catahoula Formation (table 1) that restricts vertical groundwater flow. 

Specified Head Boundaries

Water levels in the top model layer (layer 1), which represents the “400-foot” sand, “600-foot” 

sand, and “800-foot” sand, were specified with the Flow and Head Boundary (FHB) package (Leake 

and Lilly, 1997). Water-level distributions that represent the years 1944, 1980, 1984, 1990, 1998, 1999, 

and 2004 were constructed from existing data. Water levels for times between these years were linearly 

interpolated for each model cell in the top layer. Steady-state (predevelopment) water levels were 

specified at the 1944 levels and water levels for times after 2004 were specified at the 2004 levels.

Water-level maps were digitized from previous reports: predevelopment (1944) (Kuniansky, 

1989), 1980 (Martin and Whiteman, 1985a; Boswell and Arthur, 1988), 1984 (Boswell and Arthur, 
13

1988; Kuniansky, 1989), and 1990 (Tomaszewski, 1996). The water-level map for 2004 was created by

using water-level data collected by the USGS in cooperation with the Commission and DOTD. Waterlevel maps for 1998 and 1999 were created by modification of the 1990 and 2004 water-level maps

using water-level data collected at selected wells during 1998 and 1999 to more accurately specify water

levels near the Commission’s “connector well,” EB-1293 (fig. 10), which was installed in 1998 and 

screened in the “800-foot” sand and “1,500-foot” sand (Dial and Cardwell, 1999). Because little waterlevel change has occurred within the model domain in Mississippi, interpreted water levels in

Mississippi during 1982 (Boswell and Arthur, 1988) were incorporated into all of the water-level maps 

used to specify transient water levels with the FHB package. Historic water-level observations were 

used to modify the predevelopment water-level map (Kuniansky, 1989) in some areas.

A specified-head boundary was defined for the southern boundary of the bottom model layer 

(row 85, layer 22) to simulate groundwater underflow out of the model domain under predevelopment 

conditions. The water level specified for this boundary was estimated during the model calibration 

process.

Head-Dependent Flux Boundaries

The previously described groundwater withdrawals were simulated with the revised MNW2 of 

MODFLOW (Konikow and others, 2009), which was used because the screen intervals of many

withdrawal wells span multiple model layers. The MNW2 package computes a layer-by-layer 

distribution of withdrawal for each well based on the hydraulic conductivities and simulated water 

levels in each finite-difference cell connected to the simulated well-screen interval. For each annual 

stress period, the average daily withdrawal from each well was specified in cubic feet per day (ft3/d). In 

some wells water may flow between model layers when the water level simulated in a connected finitedifference cell is less than that simulated in the well. The effects of turbulent-flow head losses near the 

well and flow through drilling-damaged formation, gravel pack, or the well screen were not simulated. 

Groundwater withdrawals from wells screened in the top model layer (layer 1) corresponding to 

the “400-foot” sand, “600-foot” sand, and “800-foot” sand were not simulated because water levels in 

this layer were a specified boundary condition. One exception was the “connector well” (EB-1293) 

(Dial and Cardwell, 1999) near Baton Rouge Water Company’s Government Street pumping station 

(fig. 10), where the water-level for top-layer model layer (layer 1) was not specified. At this location the 

MNW2 package was used to simulate flow through the “connector well,” which has screens that 

intersect the “800-foot” sand (model layer 1) and the “1,500-foot” sand (model layer 5). 

Specified-Concentration Boundaries and Initial Conditions

Model cells within the solute-transport domain adjacent to the south side of the Baton Rouge 

Fault were specified as constant-concentration boundaries and therefore retain the initially assigned 

concentration throughout the simulation. The saltwater source was simulated on the south side of the 

Baton Rouge Fault in model-grid columns 30 through 70 (fig. 10), corresponding to a 4-mile long 

region east of the Mississippi River. Within this region, the specified source concentration increases 

linearly from zero above model-grid layer 9 to a maximum at the base of layer 18. Model cells south of 

the Baton Rouge Fault and west of column 30 have zero concentration, corresponding to freshwater.

Model-grid layers 1 through 8 and 19 through 22 were specified with zero initial concentration. The 

concentration of simulated water flowing from surrounding areas into the solute-transport domain is 

specified as zero, corresponding to freshwater.

North of the Baton Rouge Fault, initial concentrations were specified as zero (corresponding to 

freshwater), and variable concentrations were simulated within the “detailed model area”. Simulated 
14

concentrations were normalized to the maximum specified source concentration, which was 

parameterized and estimated through model calibration to be 10,000 mg/L of chloride. 

Hydraulic-Property Distribution

The simulated horizontal hydraulic conductivities (Kh) within the hydrogeologic units that 

represent aquifers including the “400-foot” sand, “600-foot” sand, and “800-foot” sand; the “1,000-

foot” sand and “1,200-foot” sand; the “1,700-foot” sand; the “2,400-foot” sand; and the “2,800-foot” 

sand were parameterized and estimated during model calibration. Areas within the “1,500-foot” sand 

and “1,700-foot” sand where those units “pinched out” were assigned the Kh that was used for all of the 

confining unit layers. Because the specified thickness of each of these hydrogeologic units is spatially 

variable, simulated transmissivity is spatially variable within each hydrogeologic unit. The spatial 

variation of Kh was interpolated for the hydrogeologic units representing the “1,500-foot” sand and 

“2,000-foot” sand by using pilot-points, as discussed in the following section. The magnitude of Kh in 

the north-south direction may be higher than Kh in the east-west direction within the “1,500-foot” sand

and “2,000-foot” sand because the fluvial-deltaic system that deposited these sands primarily flowed 

from north to south. Horizontal anisotropy of Kh for each of these aquifers was estimated through model 

calibration. The vertical hydraulic conductivity (Kv) for each of the hydrogeologic units representing the 

confining units (model layers 2, 4, 6, 8, 19, and 21 on the north side of the Baton Rouge Fault, 

subsequently referred to as “confining-unit layers”) that separate the aquifer layers was estimated

separately. The Kv of aquifers and Kh of confining units were homogeneously specified within their 

respective hydrogeologic-unit layers and estimated by using a single parameter for each (table 4). 

Separate parameters were defined to represent specific storage (Ss) within each aquifer and confiningunit layer. Because water levels were specified for the top model layer (layer 1), Ss for model layer 1, 

representing the “400-foot” sand, “600-foot” sand, and “800-foot” sand, had no effect on simulated 

water levels. 

Because of the importance of fault-zone conductance in controlling the transport of saltwater 

across the Baton Rouge Fault, distinct hydraulic characteristics were estimated for six lateral segments 

of the Baton Rouge Fault within the 10 model layers (layers 9–18) representing the “2,000-foot” sand

north of the fault. A single hydraulic characteristic was estimated for each of the other model layers 

(layers 3, 5, 7, 20, and 22) that contain aquifers north of the fault. 

The calibrated values of the hydraulic properties for the groundwater-flow model are 

summarized in table 4. Because 290 parameters were used to represent Kh at pilot-points within the 

“1,500-foot” sand and “2,000-foot” sand, the calibrated Kh distribution for those aquifers are graphically 

depicted in figures 12A and 12B. 

Horizontal Interpolation of Hydraulic Conductivity

Heterogeneity of horizontal hydraulic conductivity within the “1,500-foot” sand and “2,000-

foot” sand was interpolated by estimating values at 290 “pilot points” (Doherty, 2003) that were 

specified at selected well locations where borehole lithologic and (or) electric logs were available to 

constrain the estimated values. A total of 148 pilot points were used to represent the spatial variability of 

Kh within the “1,500-foot” sand and 142 pilot points were used to represent the spatial variability of Kh 

within the “2,000-foot” sand. The values of 290 parameters, each representing Kh at a single pilot point, 

were estimated during model calibration. The spatial interpolation between pilot-point locations was 

computed by ordinary kriging with an isotropic spherical variogram. The interpolated Kh distributions in 

the “1,500-foot” sand and “2,000-foot” sand were smoothed to avoid “over fitting” and constrain 

estimated values within a reasonable range by using two “regularization” methods (Doherty, 2003). The 
15

first method minimized the difference between pilot-point parameter values among neighboring pilot 

points, whereas “prior information” (Hill and Tiedeman, 2007) was assigned to the pilot points in the 

second method. The second method was deemed more appropriate and used Kh values of 100 ft/day 

based on aquifer-pumping tests (Meyer and Turcan, 1955; Morgan, 1961, 1963). Parameter values at 

pilot-point locations where an aquifer “pinched out” were fixed with Kh equal to 1 ft/day. Maps 

illustrate the simulated hydraulic-conductivity distribution resulting from the calibrated model 

parameters for the “1,500-foot” sand and “2,000-foot” sand (fig. 12 A and 12B).

Transport Properties

Solution of the advection-dispersion equation with SEAWAT required definition of the spatial 

distribution of the longitudinal, transverse, and vertical dispersivities, diffusion coefficient, and effective 

porosity of the aquifer system within the solute-transport domain. A homogeneous distribution for each 

of these properties was specified. The longitudinal, transverse, and vertical dispersivities and effective 

porosity were estimated during calibration of simulated to observed chloride concentrations. Because 

the simulated transport processes are dominated by advection, diffusion is negligible and the diffusion 

coefficient was specified equal to zero. The calibrated values of these parameters are summarized in the 

“Estimated Parameter Values” section of this report.

Model Calibration

The groundwater flow model was calibrated to obtain the best overall agreement between 

measured heads and their corresponding values simulated with MODFLOW. Although water-level 

measurements were used as observations in the model-calibration regression, groundwater fluxes were 

constrained by specification of well withdrawals. By using the parameter-estimation code PEST

(Doherty, 2004), the values of 331 parameters, which include 290 pilot-point parameters and the others 

summarized in table 4, were adjusted to minimize the objective function: 

( ) ( )

2

1

2 612,3

1

∑ )(' ∑ )(' = =

− −+

NPR

i

iiii

k

ωω HH kkkk b ωω PP b (4) 

In equation 4, symbols in the first summation are associated with water levels: H is the measured water 

level for observation k, H′ is the simulated-equivalent water level for observation k, b is the vector of 

331 model parameters, ωk is the weight applied to water-level observation k, and N is the number of 

water-level observations (3,612). Symbols in the second summation are associated with the “prior 

information” equations used for the regularization previously described in the “Horizontal Interpolation 

of Hydraulic Conductivity” section of this report: Pi is the ith prior estimate, P’i is the ith simulated 

value, ωi is the weight applied to the ith prior estimate, and NPR is the number of prior equations used 

in the regression, which equaled 267. To regularize the Kh distributions specified for the “2,000-ft” 

sand, 138 prior equations were used, and for the “1,500-ft” sand, 129 were used. 

Calibration Dataset

The model calibration dataset consisted of observations of groundwater levels, connector-well 

flow, and chloride concentrations. PEST was used to calibrate the water levels simulated with the 

constant-density MODFLOW model to observed water-levels. The observed borehole flow through the 

“connector well” (fig. 10) was compared to the value simulated for the time of the observation, which 

assisted manual calibration of the Kh specified in the top model layer. Observations of chloride 

concentrations were used to calibrate the transport model parameters. The flow model was calibrated 
16

through parameter estimation with PEST while the transport model was manually calibrated through 

trial and error. 

Water-Level Observations

A total of 4,555 water levels measured during the period between 1940 and 2007 from 161 wells 

in Louisiana were utilized for the groundwater flow model. About 80 percent (3,612) of these 

measurements were used to estimate parameters in the flow-model calibration, and the remainder (943) 

were used to evaluate the accuracy of transient water levels specified in the top model layer. In locations 

where multiple wells with overlapping periods of record exist, wells with the longest periods of 

continuous water-level record generally were selected for the compilation. Measured water-level

altitudes were between 248 and -292 ft. Measured water levels from the deeper observation wells used 

for estimation of flow-model parameters were between 215 and -292 ft, a range of 507 ft.

Well location and construction information from USGS, DOTD, and DNR records were used to 

specify the screen intervals and locations of the observation wells. Water-level observations from wells 

screened within the “400-foot” sand, “600-foot” sand, and “800-foot” sand were assigned zero weights

because water levels within layer 1 were specified throughout the simulation. Although effectively 

removed from the parameter-estimation regression, these observations were retained in the calibration 

dataset for evaluation of the water-level specification accuracy within layer 1. 

Most (3,818) water-level observations were measured in wells with screen intervals

corresponding to a single model layer, but 737 observations were measured in wells with either long or 

multiple screens that correspond to more than one model layer. In the latter cases, the measured water 

levels represent a composite of the actual head conditions in the various aquifer-depth intervals in which 

the well is screened. The majority of these multilayer observations were measured in wells screened in 

the “2,000-foot” sand, which is represented by 10 model layers with identical Kh distributions. The 

composite water level simulated for each multilayer well was computed by averaging the water levels 

simulated in all the model layers intersected by the well screen. 

Wellbore-Flow Observation

Following installation and initial development of well EB-1293, which is the “connector well” 

(fig. 10) providing a conduit between the “800-foot” sand and “1,500-ft sand, a flow rate of about 475 

gallons per minute from the “800-foot” sand to the “1,500-foot” sand was measured with a calibrated 

flow meter during December, 1998 (Dial and Cardwell, 1999). The simulated flow through the 

“connector well” was fitted to the measured flow by adjusting the Kh for model layer 1, which 

represents the “400-foot” sand, “600-foot” sand, and “800-foot” sand. Because further well 

development was conducted before the well was officially placed in service on April 6, 1999, it is 

possible that the ambient flow though the “connector well” since that time has been greater than the 

initial measurement. Multiple measurements of water levels in EB-1293 were also used for model 

calibration with PEST. 

Concentration Observations 

Two-hundred eighty three chloride-concentration observations from 16 wells within the “2,000-

foot”sand were compiled from the USGS National Water Information System (NWIS) for calibration of 

the transport simulation. Five wells (EB-781, EB-1028, EB-1150, EB-630, and EB-807B) were located 

in the area of saltwater encroachment and had sufficiently long periods of record to be useful calibration 

targets.
17

Water-Level Observation Errors

Quantification of the various sources of error that contribute to the uncertainty of water-level 

measurements is desirable for calculation of the measurement weights in the regression equations used

during model calibration. The sources of water-level measurement error in the calibration dataset were

categorized as follows: (1) errors in the measured location and altitude of the observation-well 

measurement point, and (2) errors in depth-to-water measurements. The altitudes of the measurement 

points of most water-level observation wells were interpolated from local USGS 7.5-minute quadrangle 

topographic maps that have a 5-ft contour interval. The uncertainty of each altitude determined from 

these maps is within one half of the contour interval, or 2.5 ft. Most depth-to-water level measurements 

used for model calibration were made using steel or electrical tapes with an estimated accuracy of 0.01 

ft. Water levels at flowing wells, where the water level was above land surface, were measured using 

calibrated pressure gages with an estimated accuracy of 0.1 ft. Because the vast majority of water-level 

measurements used in the model were from wells in the Baton Rouge area which have not flowed since 

the 1940s, the average error associated with the depth-to-water measurements is assumed to be 0.01 ft. 

Transient water-level fluctuations caused by processes not simulated by the model, such as atmospheric

pressure fluctuations, earth tides, or unreported groundwater withdrawals are termed “non simulated 

transient-stress errors.” Although it can be advantageous to estimate the “error” associated with such 

non simulated transient stresses to appropriately weight measurements from “noisy” water-level records, 

these errors were not considered in the observation dataset. The total error for water-level measurements 

was estimated as the sum of errors in measurement-point altitude and depth to water, which is about 2.5 

ft.

Weights

The uncertainties associated with measurement of well-head altitudes and the depth to water in 

the observation well were converted to variances and summed to obtain an error variance associated 

with each water-level measurement (Hill and Tiedeman, 2007). The inverse of this composite variance 

can be used to assign a measurement weight in the model-calibration regression. Because all well-head 

altitude and depth-to-water measurement errors in the calibration dataset were deemed to be similar, the 

resulting observation weights were normalized for observations used in the regression. Observations 

corresponding to specified head boundaries were assigned zero observation weight. Because PEST 

automatically adjusts the weight of the set of prior information equations with respect to the set of

observations during the parameter-estimation process, the relative weight assigned to the set of prior 

information equations versus the set of observations was not important. 

Calibration Assessment

The quality of the model calibration was evaluated on the basis of the reasonableness of the 

estimated parameter values, the overall fit of simulated to observed water levels measured by the 

objective function, the fit of simulated to observed chloride values, and the lack of bias in the 

distribution of positive and negative water-level residuals. Summary statistics were calculated for the 

residuals (simulated minus observed water levels) of the 3,612 water-level observations used in the 

regression. The mean magnitude of the water-level residuals was 11.4 ft. The standard error of the 

regression (Draper and Smith, 1998) was 15.7 ft. The root-mean-square error (RMSE) was calculated as 

the square root of the mean of the unweighted squared residuals: 
18

( )

3612

'

2 612,3

1

∑=

−

= k

HH kk

RMSE

 (5)

where H is the measured water level for observation k, and H′ is the simulated-equivalent water level for 

observation k. The RMSE and the standard deviation of the residuals were both 15.33 ft. The 

normalized root-mean-square deviation, obtained by dividing the RMSE of the residuals by the 507 ft 

range of observed water levels, is 0.0302. Because the RMSE is about 3 percent of the observed 

measurement range, the model is well calibrated.

Estimated Parameter Values

Parameter values were constrained within “reasonable limits” during the model calibration 

process with PEST. Several relatively insensitive model parameters drifted toward their respective 

limiting constraints between successive parameter-estimation iterations, but were not allowed to exceed 

those limits. Consequently, all of the groundwater-model parameters in the “calibrated” MODFLOW2005 and SEAWAT simulations (table 4) are considered reasonable. 

Whereas the groundwater-flow model parameters were formally estimated by minimization of 

the objective function (equation 4), parameters representing the longitudinal, transverse, and vertical 

dispersivities and effective porosity in the solute transport model were estimated by “manual” 

calibration of simulated to observed chloride concentrations. The longitudinal component of the aquifer 

dispersivity was specified homogeneously at 300 ft, the transverse at 30 ft, and the vertical at 3 ft. 

Effective porosity was homogeneously specified at 15 percent. These values are within the range of 

reasonable values for these transport parameters (Zheng and Bennett, 1995).

Parameter Sensitivities

The composite parameter sensitivity reflects the total amount of information provided by the 

water-level observations for the estimation of the model parameter (Hill and Tiedeman, 2007). PEST 

computes a “composite sensitivity” (Doherty, 2004) of each model parameter with respect to all the 

weighted simulated heads (h′i). The relative composite sensitivities of parameters included in the 

regression were calculated by multiplying the composite sensitivities computed at the final parameter 

values with their corresponding final parameter value and are summarized in table 4. 

In general, parameters with sensitivities greater than about 0.1 were well estimated and have 

correspondingly smaller confidence intervals. Parameters with composite scaled sensitivities smaller 

than about 0.1 were more difficult to estimate and (or) have larger confidence intervals.

Residual Plot

A graph of the water-level residuals (measured water levels minus simulated water levels) 

plotted as a function of the simulated water levels can be useful for detecting trends in the distribution of 

residuals, which may indicate model bias. Residuals for water levels measured north of the Baton Rouge 

Fault in the “2,000-foot” sand and in other aquifers are plotted with separate symbols in figure 13. The 

residuals for these observation groups are randomly distributed about the horizontal residual=0 abscissa, 

suggesting a lack of systematic model bias in simulated water levels.
19

Simulated Groundwater Conditions

In areas of constant groundwater density, the horizontal component of groundwater flow is 

generally in the direction of decreasing simulated water levels. Because the simulated chloride 

concentrations are relatively high in some areas adjacent to the Baton Rouge Fault, the contours of 

simulated water levels should not be used to infer the direction of groundwater flow in this area. The 

simulated water levels depicted as contour maps in this report represent conditions on December 31 of 

the indicated year. Comparisons between contour maps generated for different simulated times can be 

used to quantify water-level changes, and hydrographs of simulated and observed water levels at 

observation well locations can also be used to visualize water-level changes at various locations and 

depths within in the aquifer system. Hydrographs of simulated water levels presented in this report were

computed with the Head Observation Package (HOB), which spatially and temporally interpolates

simulated water levels at the location and time of each specified water-level observation. Changes in 

observed chloride concentration with time (chlorographs) and the corresponding concentrations 

simulated with SEAWAT are also presented in this report for selected wells.

Simulated Water Levels

Simulated groundwater flow within the “1,500-foot” sand during the “predevelopment” steadystate period prior to 1940 generally flowed from up-dip areas near the Louisiana-Mississippi border 

southward and southwestward toward the Baton Rouge area (fig. 14). Contours of simulated steadystate predevelopment water levels within the “2,000-foot” sand suggest that groundwater flowed 

southward and southwestward toward Baton Rouge in areas east of the Mississippi River and may have 

flowed in a more westerly direction in areas west of the Mississippi River (fig. 15). Simulated 

groundwater flow within the “2,000-foot” sand and “1,500-foot” sand that flows toward the northwest 

corner of the model domain discharges upward toward the specified-head boundary that represents the 

surficial aquifers.

After 68 years of groundwater withdrawals (1940–2007), simulated groundwater levels in much 

of the study area declined from their predevelopment levels. Groundwater currently flows toward the 

Baton Rouge area where withdrawals from most of the simulated aquifers have caused substantial 

drawdown of water levels (fig. 16A). Within the “1,500-foot” sand, a simulated “cone of depression” 

(area of groundwater drawdown) is centered about 0.3 mi. east of Interstate 110, where the minimum 

simulated water-level altitude is -145 ft (figs. 16A and 16B). Within the “2,000-foot” sand, the area of 

greatest simulated drawdown is located in the industrial district northeast of well EB-367, where the 

minimum simulated water-level altitude is -235 ft (figs. 17A and 17B). Lower water levels within the 

“2,000-foot” sand were simulated for years before 2007. For example, the water level simulated at the 

location of observation well EB-367, in which a water-level drawdown of 338 ft was measured between 

1937 and 1972, is about -292 ft for the year 1972. 

Hydrographs that depict the fit of simulated and observed water levels for wells in the detailed

model area (see figs. 10, 16, 17 for well locations) also show the history of water-level changes in the 

various aquifers (figs. 18–23). Except for the MNW2-calculated hydrograph for the “connector well” 

EB-1293 (fig. 19), simulated water levels depicted in the hydrographs were computed with the HOB 

package, which interpolated heads between model nodes for the well location and observation time, and 

averaged simulated heads for multi-layer observations. A spreadsheet and database containing 

hydrograph information for all observed and simulated water-levels is included with the digital archive 

of this groundwater model that is on file at the USGS office in Baton Rouge. 
20

Water levels in the “1,000-foot” sand and “1,200-foot” sand are simulated by model layer 3

north of the fault. Although a uniform hydraulic conductivity was estimated for this model layer, the 

simulated transmissivity is variable because the model-layer thickness is variable. The fit of simulated 

to observed water levels shown in hydrographs (fig. 18) is good, and the 170 ft of drawdown observed 

in well EB-146, (located about 0.9 miles east of Interstate 10 in Baton Rouge), is well simulated.

Simulated water levels at some wells (EB-146, EB-299, and EB-301) are lower than observed during 

the 1960s and early 1970s, possibly as a result of inaccurate pumpage specified within this layer for 

those periods. 

Water levels in the “1,500-foot” sand north of the fault were simulated by model layer 5 by 

using a complex distribution of horizontal hydraulic conductivity (fig. 12A). The hydrograph for well 

807A documents the largest observed water-level drawdown in the “1,500-foot” sand, which was about 

82 ft between the years 1967 and 1992 (fig. 19). Two sets of simulated water-level hydrographs are 

depicted for the “connector well”, EB-1293 (fig. 19). The flow-weighted composite water levels 

calculated by the MNW2 package for each time step compose a second hydrograph and are shown in 

addition to the HOB-calculated water levels. 

Water levels for the “1,700-foot” sand were simulated with model layer 7 north of the fault by

using a homogeneous horizontal hydraulic conductivity distribution. The water-level recovery at well 

EB-792 during the early 1970s was not simulated by the model (fig. 20), possibly as a result of 

inaccurate pumpage specified within this layer in the vicinity of EB- 792 for that period. 

Water levels in the “2,000-foot” sand were simulated by model layers 9 through 18, each of 

which has an identical, complex distribution of simulated horizontal hydraulic conductivity (fig. 12B). 

Observations of water levels in the “2,000-foot” sand are closely simulated throughout most of the 

model domain, and particularly in the detailed model area. Locations of wells that are screened within 

the “2,000-foot” sand in the detailed model area that were used for model calibration are shown on 

figure 17B. A 368-ft water-level drawdown measured in well EB-112 between 1930 and 1973 is well 

simulated (fig. 21B). Water-level drawdowns of similar magnitude measured in other wells in the 

detailed model area are also well simulated by the model.

Water levels in the “2,400-foot” sand were simulated by model layer 20 with homogeneous 

hydraulic conductivity. Water levels measured in two wells within the detailed model area, EB-794 and 

EB-806B (fig. 10), document about 100 ft of water-level drawdown between 1965 and 2007 (figs. 

22Figure 22A and 22B). Considering the relatively simple hydraulic-conductivity distribution used to 

simulate the “2,400-foot” sand, water levels throughout the model domain are well simulated.

Because chloride concentrations in the “2,800-foot” sand are relatively high in the Baton Rouge 

area, only one well, EB-944 (fig. 23), screened in the “2,800-foot” sand was available to depict water 

levels in the detailed model area (fig. 10). Despite the scarcity of observation wells screened in the 

“2,800-foot” sand in the detailed model area, 15 other hydrographs within the “2,800-foot” sand outside 

of the detailed model area (not shown) also depict good model fit. 

Simulated Connector-Well Flow Rate

The simulated transient flow through the “connector well”, EB-1293, was compared with the 

previously described wellbore-flow observation during model calibration. The simulated flow rate of 

504 gallons per day (gal/d) through this well during December, 1998, is a good fit to the reported value 

of 475 gallons per day measured in that month. The flow simulated through this “connector well” 

increases after December 1999 because simulated water levels within the “1,500-foot” sand generally 

decline faster than water levels specified for the “800-foot” sand, which increases the hydraulic gradient 
21

between those aquifers at that location. The maximum simulated flow rate of 682 gallons per day 

occurred during 2007. 

Simulated Water Budget

Under predevelopment (steady-state) conditions, the simulated water budget indicates that about 

69 Mgal/d of water enters (and exits) the groundwater-flow model domain (table 5). All of the inflow is

from the top model layer, which is a specified head boundary that represents the “400-foot” sand, “600-

foot” sand, and “800-foot” sand aquifers, into underlying hydrogeologic units. By the end of the 

transient historical simulation (December 31, 2007), substantial net groundwater withdrawals (167.25 

Mgal/d during 2007) had caused water-level declines that increased simulated infiltration from layer 1 

by 71 percent, to 118.9 Mgal/d. Water that flows in to a model layer through a multi-node well comes 

out from another model layer connected to the same well. Specified water-level changes in the top 

model layer account for processes not explicitly simulated by the model, including storage changes in

the upper “400-foot” sand, “600-foot” sand, and “800-foot” sand aquifers, evapotranspiration, and 

recharge. As such, recharge and discharge to the upper aquifers are not represented in the simulated 

water budget. Inflows from storage simulated in model layers 2–22 are from aquifer-matrix compression 

and water expansion. 

A graph (fig. 24) of the changes in the contributions from the three major sources and sinks of 

water during the transient historical groundwater simulation illustrates the effect of groundwater 

withdrawals on the simulated water budget. Following the steady-state stress period that simulates 

“predevelopment” conditions prior to 1940, groundwater withdrawals are initially mostly supplied by 

the elastic release of water from storage. Over time, vertical hydraulic gradients caused by groundwater 

withdrawals from the deeper model layers cause increasing downward flow from the top model layer 

specified-head boundary that represents the upper aquifers. Flow from storage continues to respond to 

shorter term changes in the pumpage stress. Flow from specified-head boundaries is relatively smooth

through time (fig. 24) because it is computed during every time step. In contrast, groundwater 

withdrawals are specified by stress periods composed of multiple time steps, and flow from storage 

responds to these specified withdrawals. 

Simulated Concentrations

Because the chloride-source concentration is unknown, it was parameterized and estimated 

during model calibration. To facilitate calibration to observed concentrations, simulated concentrations

were normalized to the source concentration. A chloride-source concentration of 10,000 mg/L produced 

the best overall fit of simulated to observed chloride concentrations. Simulated chloride concentrations 

at the centers of model cells containing chloride-observation well screens were used to generate the 

simulated chlorographs (fig. 25), the locations of which are mapped in figure 26. Simulated chloride 

concentrations in two or more vertically adjacent model cells were averaged for chloride observation 

wells with screens spanning more than one model layer within the “2,000-foot” sand. 

Two factors complicated simulation of the concentrations observed in observation well EB-781, 

the screen of which is located about 250 ft north of the Baton Rouge Fault. First, although the precise 

location of the Baton Rouge Fault at the “2,000-foot” sand depth is somewhat uncertain, it was defined 

along the finite-difference cell interfaces nearest to its presumed location. Because the finite-difference 

grid cell spacing is 500 ft in this area, the error inherent in the simulated fault location is likely on the 

order of 250 ft. Second, the steep simulated concentration gradient near the north side of the Baton 

Rouge Fault causes a large difference in simulated concentration between the model cell north of and 

adjacent to the fault and its neighboring cell to the north. The concentrations simulated for two cells 
22

north of the fault are illustrated by the curves labeled “simulated row 72” and “simulated row 73” in 

figure 25A . Because a reasonable fit to the observed concentrations was obtained with the curve labeled 

“simulated row 73,” which simulates the concentration 250 ft north of the Baton Rouge Fault, the 

transport simulation is considered well calibrated to observations in well EB-781. 

Although the most recent chloride concentration observation in well EB-807B, (located about 

0.7 mile north of well EB-871) was made in 1998, the relatively low concentrations measured before 

that time provide a useful constraint on model parameters affecting the transport of the salty water in a 

northerly direction away from source areas near EB-781 and the Baton Rouge Fault. 

Chloride concentrations measured in wells EB-1150 and EB-630 (figs. 25D and 25E) have 

fluctuated over the period of the observation record. These fluctuations are difficult to simulate while 

maintaining relatively parsimonious initial and boundary conditions and transport-model parameter 

distributions. Consequently, simulated chlorographs for these wells are a reasonable fit to intermediate 

values within the range of fluctuations in the observed concentrations. 

Limitations and Appropriate Use of the Model

The groundwater model was designed and calibrated primarily to simulate groundwater flow in 

the “1,500-foot” sand and “2,000-foot” sand and saltwater transport within the “2,000-foot” sand of the 

Baton Rouge area. Because the model layering was designed to represent the most important 

hydrogeologic units of the aquifer system and water-level observations from all aquifers in the Baton 

Rouge area were used for model calibration, groundwater flow within the “1,000-foot” sand and “1,200-

foot” sand, “1,500-foot” sand, “1,700-foot” sand, “2,400-foot” sand, and “2,800-foot” sand is 

reasonably well simulated. It is possible to simulate the effects of future changes in groundwater 

withdrawals on groundwater levels in each of these sands in the Baton Rouge area. Predictions of 

changes in water levels in the “1,500-foot” sand and “2,000-foot” sand that might result from changes 

such as those described in the subsequent section on hypothetical groundwater management scenarios 

are examples of appropriate uses of the model. The period before 1940 was simulated with a steadystate solution of the flow equation, during which transient effects of any minor groundwater 

withdrawals were not simulated.

Chloride concentrations within the “2,000-foot” sand in the Baton Rouge area were used to 

calibrate the model; consequently, saltwater encroachment in other aquifers in the Baton Rouge area is 

not accurately simulated. Predictions of changes in chloride concentrations within the “2,000-foot” sand

that might result from changes such as those described in the subsequent section on hypothetical 

groundwater management scenarios is an appropriate use of the model. Predictions of changes in 

chloride concentrations within the “1,500-foot” sand or other aquifers is not appropriate because the 

model was not calibrated to chloride-concentration observations within other aquifers. 

The variably spaced finite-difference model grid enabled fine discretization with greater 

numerical accuracy in the Baton Rouge area and coarse and large aspect-ratio (long side divided by 

short side) with less numerical accuracy in the surrounding areas. Water levels predicted for areas with 

either very coarse of very large aspect-ratio model cells will be less accurate, and should be used 

judiciously. 

Hypothetical Groundwater Management Scenarios

Five hypothetical groundwater management scenarios were formulated to predict the effects of 

modifying groundwater withdrawals on future groundwater levels and saltwater concentrations. Each 

scenario used a constant pumping rate for a 40-year period from 2008 through 2047. Scenario 1 
23

simulates continuation of the “status quo” 2007 groundwater-withdrawal rates and is a benchmark for 

comparison of water levels and (or) chloride concentrations simulated in the other four scenarios. 

Scenario 2 simulated the effect of reducing groundwater withdrawals from seven selected industrial 

wells by 10.8 Mgal/d on water levels in the “1,500-foot” sand. Scenarios 3, 4, and 5 simulate alternative 

strategies for mitigating the northward migration of saltwater within the “2,000-foot” sand: scenarios 3a 

and 3b simulate alternative scavenger well locations at the base of the “2,000-foot” sand; scenario 4 

simulates a 3.6 Mgal/d withdrawal reduction from the “2,000-foot” sand; and scenario 5 simulates 

cessation of withdrawals from the “2,000-foot” sand within the industrial district.

In addition to the existing chloride-observation wells, the concentration at a hypothetical 

observation well EB-X located south of the industrial district (fig. 26) is simulated for each scenario. 

The “plume area,” defined as the area with simulated chloride concentration greater than 10 mg/L in 

model layer 18 (the base of the “2,000-foot” sand) north of the Baton Rouge Fault, and the mean and 

median cell concentrations within that area for the start (2007) and end of each 40-year scenario are 

summarized in table 6. 

Scenario 1: Continued Groundwater Withdrawals at 2007 Rates

Continuation of the “status quo” groundwater withdrawals was simulated by specification of the 

2007-reported withdrawal rates for an additional 40 years. Contours of predicted water-levels within the

“1,500-foot” sand (fig. 27) for 2047 are similar to those simulated for 2007 (fig. 16) but are consistently 

about 6 ft lower throughout the Baton Rouge area. The lowest water-level altitudes of about -150 ft are 

simulated 2 miles north-northwest of observation well EB-1293. 

Continued groundwater withdrawals at 2007 rates are predicted to cause further decline of 

groundwater levels within the “2,000-foot” sand. Although the shape of contours of predicted water 

levels within the “2,000-foot” sand (fig. 28) for 2047 are similar to those for 2007 (fig. 17), the water 

levels are about 17 ft lower in the Baton Rouge area. The lowest water-level altitudes of about -250 ft

are simulated in the industrial district.

Comparison of the simulated chloride concentrations in layer 18 for year 2047 (Figure 28) with 

the simulated 2007 concentration distribution (fig. 26) indicates that the portion of the saltwater plume 

containing chloride concentrations in the 161–320 mg/L range at the base of the “2,000-foot” sand 

would migrate approximately 0.6 miles northward toward the industrial district. The area at the base of 

the “2,000-foot” sand north of the Baton Rouge Fault with concentrations above background levels (10 

mg/L) would increase by about 25 percent (table 6). Concentrations at most existing observation wells 

would increase, and the concentration at EB-X, near the center of the plume south of the industrial 

district (fig. 28), is predicted to increase from about 27 mg/L to about 195 mg/L within about 30 years 

(fig.29F). Concentrations at observation well EB-630 are predicted to decrease because groundwater 

flow at that location is from the south where the aquifer south of the fault may be fresh and the saltwater

source is not simulated. 

Scenario 2: Reduction of Groundwater Withdrawals from the “1,500-foot” Sand

Saltwater encroachment is also a concern within the “1,500-foot” sand in the Baton Rouge area. 

Similar to the saltwater encroachment problem within the “2,000-foot” sand, this encroachment is 

caused by water-level drawdown caused by withdrawals from the “1,500-foot” sand. Although transport 

of saltwater was not calibrated for the model documented in this report, the simulation of transient water 

levels within the “1,500-foot” sand enabled assessment of a possible groundwater-withdrawal reduction 

on water levels in the “1,500-foot” sand. Of particular interest is the contribution to water-level

drawdown in the “1,500-foot” sand caused by withdrawals from selected industrial wells in the 
24

northwest corner of East Baton Rouge Parish (fig. 10). This contribution was assessed as the difference 

between the 2047 water levels simulated with scenario 1 and the 2047 water levels simulated with the 

selected industrial wells turned off from 2008 through 2047. For scenario 2, zero withdrawal rates were 

specified from seven industrial wells that have screens either in the “1,500-foot” sand or an adjacent 

sand, simulating a withdrawal reduction of 10.8 Mgal/d. Two wells (EB-963 and PC-343) have 

simulated screen intervals only within the “1,500-foot” sand. Four wells (EB-835, EB-837, EB-1248, 

and EB-1277) have simulated screen intervals within the “1,500-foot” sand and “1,700-foot” sand. 

Although the screen of one well (EB-838) is entirely within the “1,700-foot” sand, it was included 

because pressure changes within the “1,700-foot” sand may propagate to the “1,500-foot” sand through 

the intervening confining layer. 

Comparison of the contours of water levels predicted for 2047 within the “1,500-foot” sand for 

scenarios 1 and 2 (figs. 27 and 30) indicated that 2047 water-level altitudes for scenario 2 are generally 

about 15 to 20 ft higher in the Baton Rouge area than those predicted for scenario 1. The lowest

predicted water-level altitudes, about -130 ft, are around municipal supply wells located about 2 mi. 

southeast of the industrial district. 

Because water-level changes within the aquifer system propagate between aquifers through the 

intervening aquifers and confining layers, the simulated decrease in groundwater withdrawals from the 

“1,500-foot” and “1,700-foot” sands under scenario 2 also affects water levels simulated within the 

“2,000-foot” sand. Water-levels simulated for 2047 in the “2,000-foot” sand with scenario 2 indicate 

that groundwater-flow directions within the “2,000-foot” sand are similar to scenario 1, but water levels 

are about 7 ft higher than the 2047 water levels in scenario 1. 

Scenario 3: Scavenger Well Withdrawal from the Base of “2,000-foot” Sand

One proposed strategy to mitigate the northward migration of the saltwater plume is the 

installation and operation of a “scavenger” well that is screened at the base of the “2,000-foot” sand, 

where multidepth observations of chloride concentrations within the aquifer have indicated that higher 

concentrations exist (Tomaszewski, 1996). The scavenger well would withdraw the higherconcentration groundwater from the base of the aquifer, which would subsequently require 

desalinization and (or) disposal. For scenario 3, the effects of pumping 2 Mgal/d from the bottom (layer 

18) of the “2,000-foot” sand on water levels and chloride concentrations were simulated for two 

possible scavenger-well locations. 

Water-levels simulated for 2047 in the “2,000-foot” sand in scenario 3 are about 15 ft lower than 

those predicted for scenario 1 (the “status quo” simulation), and the lowest water-levels are predicted in 

the same locations of the industrial district as in scenario 1 (figs. 31 and 32). Water-level contours 

depict the drawdown around the scavenger wells, where 2047 water-level altitudes of about -260 ft are 

simulated. 

For scenario 3a, the scavenger well was simulated in model row 57, column 26 (fig. 31). 

Predicted 2047 chloride concentrations in layer 18 (the base of the “2,000-foot” sand) indicate that 

although the lowest-concentration front of the saltwater plume continues to migrate northward toward 

withdrawal wells in the industrial-district, the concentrations between the scavenger well and the 

industrial district are lower than in scenario 1 (fig. 26). Higher chloride concentrations within the central 

portion of the plume between the scavenger well and the Baton Rouge Fault might result from more 

movement of saltwater because of the larger hydraulic gradients generated by the 2 Mgal/day 

withdrawal from the scavenger well. 

For scenario 3b, a scavenger well was simulated in model row 68, column 30 (fig. 32). Predicted 

2047 chloride concentrations in layer 18 indicate that the saltwater plume would also continue to 
25

migrate northward toward withdrawal wells in the industrial-district with concentrations lower than in 

scenario 1. Predicted chloride concentration within the central portion of the plume between this 

scavenger well location and observation wells EB-630 and EB-1150 are lower than those predicted for 

either scenario 1 or scenario 3a (the other scavenger-well location).

In comparison to the concentrations simulated in scenario 1, operation of the scavenger well in 

the locations specified in scenarios 3a and 3b reduces the chloride concentrations at all existing 

chloride-observation well locations (fig. 29). At EB-X, the hypothetical observation location near the 

leading-edge of the plume, predicted 2047 chloride concentrations decrease from the 195 mg/L

predicted in scenario 1 to 25 mg/L and 62 mg/L for scenarios 3a and 3b, respectively (fig. 29F). 

Scenario 4: Reduction of Groundwater Withdrawals from the “2,000-foot” Sand in the Baton Rouge 

Industrial District

Reduction of groundwater withdrawals from the “2,000-foot” sand in the Baton Rouge industrial 

district would decrease the hydraulic gradient toward that area and limit the northward advective 

transport of saltwater. A reduction of 3.6 Mgal/d (from 25 Mgal/d to 21.4 Mgal/d) from selected wells 

screened in the “2,000-foot” sand in the industrial district was simulated over the 40-year period from 

2008 to 2047. 

Contours of water levels predicted within the “2,000-foot” sand (fig. 33) for 2047 illustrate 

similar groundwater flow to that predicted for scenario 1 but are generally between 25 and 35 ft higher 

in the Baton Rouge area. The lowest water-level altitude of about -215 ft is predicted within the 

industrial district in the same location as that predicted for scenario 1. 

The map of simulated chloride concentrations for 2047 at the base of the “2,000-foot” sand (fig. 

33) indicates that the saltwater plume would continue to migrate northward toward the industrial district

withdrawal wells following a 3.6 Mgal/d withdrawal reduction. The simulated concentration at EB-X is

110 mg/L (fig. 29F), which is less than the 195 mg/L predicted for scenario 1. In contrast, 

concentrations at observation wells EB-1028 and EB-807B increase with respect to scenario 1 because 

decreased flow toward the industrial district results in relatively more flow toward the area of municipal 

withdrawals 1 mi. north of EB-807B. The median and mean plume concentrations are slightly lower

than scenario 1 (table 6), and the area with chloride concentration greater than about 80 mg/L is about 4 

percent smaller than that predicted in scenario 1. 

Scenario 5: Cessation of Groundwater Withdrawals from the “2,000-foot” Sand in the Baton Rouge 

Industrial District

Zero withdrawals from 24 production wells in the industrial district were specified for the 40-

year period to simulate industrial-district withdrawal cessation, which causes a reduction of 16.5 Mgal/d 

(from 25 Mgal/d to 8.5 Mgal/d) in total withdrawal from the “2,000-foot” sand. In comparison to 

scenario 1, this scenario simulated the largest increase in water levels and change in chloride 

concentrations within the “2,000-foot” sand. The simulated 2047 water-level altitudes within the

“2,000-foot” sand (fig. 34) are 95 to 165 ft higher than those in scenario 1, and the direction of 

groundwater flow in the Baton Rouge area differs. Whereas in scenarios 1 through 4 groundwater flow 

in the “2,000-foot” sand is generally toward the area of water-level drawdown under the industrial 

district, in scenario 5 groundwater flows toward an area of water-level drawdown about 0.5 mi. north of 

EB-807B (fig. 34). Minimum groundwater levels of about -114 ft reflect the continued municipal 

withdrawals from the “2,000-foot” sand in this area. 

The simulated chloride-concentration distribution (fig. 34) in this scenario reflects the change in 

groundwater flow direction. Although some saltwater would continue to cross the Baton Rouge Fault 
26

and encroach toward municipal supply wells in the area of drawdown about 0.5 mi north of EB-807B, 

further encroachment toward the industrial district would be abated. Saltwater within the “2,000-foot” 

sand that is presently encroaching south of the industrial district (fig. 26) would be replaced by 

freshwater flowing from the northwest. The simulated chloride concentration at the base of the “2,000-

foot” sand at EB-X decreases to “background concentrations” below 10 mg/L by about 2025 (fig. 29F). 

Because saltwater is no longer transported toward the industrial district in this scenario, relatively more 

of it is transported toward the area of municipal groundwater withdrawals north of EB-807B. 

Consequently, chloride concentrations simulated at well EB-807B are approximately twice those in 

scenario 1. Simulated chloride concentrations at EB-1028 and EB-1150 initially increase as higherconcentration water west of those observation wells begins to flow eastward, but subsequently decline 

as it is replaced by fresher water from west of the plume. Simulated concentrations in EB-781 remain 

similar to the other scenarios because it is close to the source, where concentrations are less sensitive to 

the simulated pumping distribution. 

Summary 

Groundwater withdrawals in the Baton Rouge area since the 1940s have lowered water levels 

and altered groundwater-flow directions in the underlying freshwater aquifers of the fluvial-deltaic 

Southern Hills aquifer system. The drawdown of groundwater levels has caused saltwater to encroach 

into previously freshwater areas in the Baton Rouge area. Saltwater encroachment has been detected 

north of the Baton Rouge Fault in East Baton Rouge Parish in 7 of the 10 Baton Rouge sands, including 

the “1,500-foot” sand and “2,000-foot” sand. Generally, aquifers south of the Baton Rouge Fault contain 

saltwater and aquifers north of the fault contain freshwater. The 10 aquifers that underlie the Baton 

Rouge area, which includes East and West Baton Rouge Parishes, Pointe Coupee Parish, and East and 

West Feliciana Parishes, provided about 167 million gallons per day (Mgal/d) for public supply and 

industrial use in 2010. Groundwater withdrawals from the “2,000-foot” sand, which totaled 23.9 Mgal/d 

during 2010, have resulted in measured water-level drawdowns of up to 356 feet (ft) and saltwater 

migration from south of the fault into the “2,000-foot” sand. This saltwater threatens industrial wells 

located about 3 miles north of the fault, which account for about 66 percent of the withdrawals from the 

“2,000-foot” sand in East Baton Rouge Parish. A groundwater flow and saltwater transport model was 

constructed to assess the effects of groundwater withdrawals on the rate and pathways of saltwater 

migration.

Because density differences between groundwater areas with contrasting saltwater 

concentrations may affect groundwater flow between those areas, both constant- and variable-density 

simulations of groundwater flow were utilized. The groundwater-flow simulation was initially 

constructed with MODFLOW and calibrated to observed water levels with PEST. The calibrated 

groundwater-flow model parameters were subsequently utilized for the variable-density SEAWAT 

version of the model. Although much of the model input for SEAWAT is identical to MODFLOW 

input, withdrawal fluxes previously computed with the MODFLOW multi-node well package were used 

to specify WEL package input for SEAWAT. Additional input was constructed to define transport 

boundary and initial conditions, transport properties, and specification of the equation of state relating 

solute concentration to groundwater density. The groundwater flow and solute-transport equations are 

coupled because SEAWAT iteratively solves each equation for every transport time step such that 

computed concentrations affect groundwater density and can therefore influence groundwater velocities. 

A 3-dimensional hydrogeologic framework was constructed to define the extents and thicknesses 

of the aquifers and confining units in the study area. The framework consists of 22 layers that represent 

the entire sequence of sands and clays from land surface to the base of the “2,800-foot” sand. Layers 1, 
27

3, 5, 7, 9–18, 20, and 22 make up the aquifer layers. Layers 2, 4, 6, 8, 19, and 21 make up confining 

units that separate the aquifer layers. Layers 1 and 3 represent multiple aquifers that have similar 

hydraulic characteristics and are likely interconnected. Layer 1 represents the Mississippi River alluvial 

aquifer, shallow sands, upland terrace aquifer, and the “400-foot” sand, “600-foot” sand, and “800-foot” 

sand. Layer 3 includes the “1,000-foot” sand and “1,200-ft” sand. The “2,000-foot” sand is represented 

by 10 layers numbered 9 through 18. 

A finite-difference grid with lateral cell dimensions of 500 by 500 ft in the Baton Rouge area 

uses increasing cell spacing toward the model-domain boundaries so that the entire 6,529 square mile 

study area is discretized with 85 rows and 85 columns of finite-difference cells. Vertical finitedifference discretization was defined such that model-cell layers correspond to the tops of 

hydrogeologic-framework units north of the Baton Rouge Fault and are horizontal along columns from 

the fault southward. Because the Hydrogeologic-Unit-Flow Package was used to define the 

hydrogeologic-framework geometry independently from finite-difference discretization, this 

discretization scheme facilitated simulation of flow between hydrogeologic units where they are 

juxtaposed at the Baton Rouge Fault. Additional resistance to flow across the Baton Rouge Fault was 

simulated with horizontal flow barriers. Following an initial steady-state stress period that simulated 

predevelopment conditions prior to 1940, 68 annual transient stress periods simulated time from 1940 

through 2007. Four additional 10-year stress periods were used for scenarios that simulate future 

conditions through 2047. 

Boundary conditions utilized for the groundwater-flow simulation included specified flux, 

specified head, and head-dependent flux types. Transient water levels within the top model layer, which

represents the “400-foot” sand, “600-foot” sand, and “800-foot” sand were specified by linear 

interpolation between levels constructed for 1944, 1980, 1984, 1990, 1998, 1999, and 2004. Water 

levels in the top model layer for simulated times before 1944 and after 2004 were specified at the 1944 

and 2004 levels, respectively. A constant-head boundary was specified along row 85 in the bottom 

model layer, which corresponds to the southernmost extent of the “2,800-foot” sand. The water-level for 

this boundary, which was estimated as a parameter during model calibration, enabled simulation of 

underflow to the south and out of the aquifer system before development. The remaining lateral and 

lower boundaries of the flow domain were simulated as no-flow boundaries. The layer-by layer 

distributions of withdrawals simulated by the MODFLOW multi-node well package depends upon 

water levels simulated in the connected model layers and are therefore head-dependent fluxes. The 

equivalent fluxes specified with the WEL package for the SEAWAT simulation are the specified-flux 

type.

Average daily withdrawal rates were specified for 605 wells with the multi-node well package 

for each annual stress period from 1940 through 2007. After calibration of the MODFLOW model, the 

simulated layer-by-layer fluxes in and out of each well were specified as WEL package input for the 

SEAWAT simulation.

The area in which solute transport was simulated with SEAWAT is a subset of the flow model 

domain and corresponds to the 50 row by 55 column portion of the grid with 500 by 500 ft finitedifference cells in the Baton Rouge area. Model-grid cells within this area south of the Baton Rouge 

Fault are constant-concentration boundaries; cells north of the fault are variable-concentration cells for 

which a concentration was calculated for each transport time step.

The initial chloride concentration within model-grid cells adjacent to the south side of the Baton 

Rouge Fault, east of column 30, and from model-grid layers 9 through 18 (inclusive) was specified to 

increase linearly with depth from zero to a maximum concentration, which was parameterized and 

estimated during model calibration to be 10,000 milligrams per liter (mg/L). These model grid layers are 
28

laterally connected to the 10 layers that simulate the “2,000-foot” sand north of the fault. All other 

portions of the solute transport domain were assigned a zero initial concentration.

The groundwater-flow model was calibrated to 3,612 water levels measured between 1940 and 

2007 from 137 observation wells with the parameter-estimation code PEST. An additional 943 water 

levels measured in 24 wells screened in the top model layer were included in the calibration dataset to 

evaluate the accuracy of the specified-head boundaries in the top model layer but had no influence on 

the parameter-estimation regression. The estimated values of hydraulic-property parameters were all 

within the range considered reasonable. 

Five hypothetical scenarios simulated the effects of different groundwater withdrawal options on 

groundwater levels within the “1,500-foot” sand and the “2,000-foot” sand and the transport of 

saltwater within the “2,000-foot” sand. Each scenario simulated constant withdrawal rates for a 40-year 

period from 2008 through 2047. Scenario 1 is considered a base case for comparison to the other four 

scenarios and simulates continuation of 2007 reported groundwater withdrawals. Scenario 2 simulates 

discontinuation of withdrawals from seven selected industrial wells located in the northwest corner of 

East Baton Rouge Parish that are screened either in the “1,500-foot” sand or an adjacent aquifer. Water 

levels within the “1,500-foot” sand were predicted to be about 15 to 20 ft higher under this withdrawal 

scenario than under scenario 1. 

Three other scenarios test various groundwater withdrawal options on the water levels and 

predicted chloride concentrations within the “2,000-foot” sand. Scenario 3 simulates the effects of a 

scavenger well at two possible locations on water levels and concentrations within the “2,000-foot” 

sand. The scavenger well would withdraw water from the base of the “2,000-foot” sand at a rate of 2 

Mgal/d. Scenario 4 simulates a 3.6 Mgal/d reduction in total groundwater withdrawals from selected 

wells screened in the “2,000-foot” sand that are located in the Baton Rouge industrial district. Scenario 

5 simulates the effect of total cessation of groundwater withdrawals from the “2,000-foot” sand in the 

industrial district. In comparison to the concentrations simulated in scenario 1, operation of the 

scavenger well in the locations specified in scenario 3 reduces the chloride concentrations at all existing 

chloride-observation well locations. For scenario 4, the median and mean plume concentrations are 

slightly lower than scenario 1, and the area with chloride concentration greater than about 80 mg/L is 

about 4 percent smaller than that predicted in scenario 1. The simulated chloride-concentration 

distribution in scenario 5 reflects the change in groundwater flow direction. Although some saltwater 

would continue to cross the Baton Rouge Fault and encroach toward municipal supply wells in the area 

of drawdown about 1.5 mi. north of the fault, further encroachment toward the industrial district would 

be abated.

Selected References

Anderman, E.R., and Hill, M.C., 2000, MODFLOW–2000, The U.S. Geological Survey modular 

ground-water model—Documentation of the Hydrogeologic-Unit Flow (HUF) package: U.S. 

Geological Survey Open-File Report 00–342, 89 p. 

Atwood, W.W., 1940, The physiographic provinces of North America: Boston, Ginn and Company, 

535 p. 

Bates, R.L., and Jackson, J.A., eds., 1984, Dictionary of geological terms (3d ed.): New York, 

Doubleday, 571 p. 

Bieber, P.P., and Forbes, M.J., Jr., 1966, Pumpage of water in Louisiana, 1965: Department of 

Conservation, Louisiana Geological Survey, and Louisiana Department of Public Works Water 

Resources Pamphlet 20, 8 p. 
29

Boniol, D.P., Autin, W.J., and Hanson, B.C., 1988, Recharge potential of Louisiana aquifers—A 

supplement to the State aquifer recharge map and atlas plates: Baton Rouge, La., Louisiana 

Geological Survey Open-File Series 88–07, 50 p. 

Boswell, E.H., and Arthur, J.K., 1988, Generalized potentiometric surface of shallow aquifers in 

southern Mississippi, 1982: U.S. Geological Survey Water-Resources Investigations Report 87–4257, 

1 sheet.

Buono, Anthony, 1983, The Southern Hills regional aquifer system of southeastern Louisiana and 

southwestern Mississippi: U.S. Geological Survey Water-Resources Investigations Report 83–4189, 

38 p. 

Calhoun, Milburn, and Frois, Jeanne, eds., 1997, Louisiana almanac (1997–98 ed.): Gretna, La., Pelican 

Publishing Company, 695 p. 

Cardwell, G.T., and Walter, W.H., 1979, Pumpage of water in Louisiana, 1975: Louisiana Department 

of Transportation and Development, Office of Public Works Water Resources Special Report no. 2, 

15 p. 

Dial, D.C., 1968, Water-level trends in southeastern Louisiana: Department of Conservation, Louisiana 

Geological Survey, and Louisiana Department of Public Works Water Resources Pamphlet no. 22, 

11 p. 

Dial, D.C., 1970, Pumpage of water in Louisiana, 1970: Department of Conservation, Louisiana 

Geological Survey, and Louisiana Department of Public Works Water Resources Pamphlet 26, 10 p. 

Dial, D.C., and Cardwell, G.T., 1999, A connector well to protect water-supply wells in the "1,500-ft" 

sand of the Baton Rouge, Louisiana area from saltwater encroachment: Capital Area Ground Water 

Conservation Commission Bulletin no. 5, 17 p. 

Dial, D.C., and Sumner, D.M., 1989, Geohydrology and simulated effects of pumpage on the New 

Orleans aquifer system at New Orleans, Louisiana: Louisiana Department of Transportation and 

Development Water Resources Technical Report no. 46, 54 p. 

Doherty, John, 2003, Ground water model calibration using pilot points and regularization: Ground 

Water, v. 41, no. 2, p. 170–177. 

Doherty, John, 2004, PEST—Model-independent parameter estimation, user manual (5th ed.): Corinda, 

Australia, Watermark Numerical Computing, 336 p. 

Draper, N.R., and Smith, H., 1998, Applied regression analysis, 3rd ed: John Wiley & Sons, New York, 

NY, 706 p. 

Dunlap, L.E., and Spinazola, J.M., 1984, Interpolating water-table altitudes in west-central Kansas using 

kriging techniques: U.S. Geological Survey Water-Supply Paper 2238, 19 p. 

Durham, C.O., Jr., and Peeples, E.M. III, 1956, Pleistocene fault zone in southeastern Louisiana [abs.]: 

New Orleans, La., Transactions of the Gulf Coast Association of Geological Societies, v. 6, p. 65–66. 

Fisk, H.N., Richards, H.G., Brown, C.A., and Steere, W.C., 1938, Contributions to the Pleistocene 

history of the Florida Parishes of Louisiana: Department of Conservation, Louisiana Geological 

Survey Geological Bulletin no. 12, 137 p. 

Griffith, J.M., 2003, Hydrogeologic framework of southeastern Louisiana: Louisiana Department of 

Transportation and Development Water Resources Technical Report no. 72, 21 p., 18 pl. 

Griffith, J.M., 2006, Hydrogeologic maps and sections of the “400-foot,” “600-foot,” and “800-foot” 

sands of the Baton Rouge Area and adjacent aquifers in East and West Baton Rouge, East and West 

Feliciana, and Pointe Coupee Parishes, Louisiana: U.S. Geological Survey Scientific Investigations 

Report 2006–5072, 15 p., 13 pl. 
30

Griffith, J.M., and Lovelace, J.K., 2003, Louisiana ground-water map no. 15—Potentiometric surface of 

the “1,200-foot” sand of the Baton Rouge area, Louisiana, spring 2001: U.S. Geological Survey 

Water-Resources Investigations Report 03–4020, scale 1:385000, 2 sheets. 

Griffith, J.M., and Lovelace, J.K., 2003, Louisiana ground-water map no. 16—Potentiometric surface of 

the “1,500-foot” sand of the Baton Rouge area, Louisiana, spring 2001: U.S. Geological Survey 

Water-Resources Investigations Report 03–4021, scale 1:385000, 2 sheets. 

Halford, K.J., and Lovelace, J.K., 1994, Analysis of ground-water flow in the “1,200-foot” aquifer, 

Baton Rouge area, Louisiana: Louisiana Department of Transportation and Development Water 

Resources Technical Report no. 54, 68 p. 

Hanor, J.S., 1982, Reactivation of fault movement, Tepetate fault zone, south central Louisiana, in

Transactions of the Gulf Coast Association of Geological Societies: Gulf Coast Association of 

Geological Societies, v. 32, p. 237–245. 

Harbaugh, A.W., 2005, MODFLOW-2005, the U.S. Geological Survey modular ground-water model—

The ground-water flow process: U.S. Geological Survey Techniques and Methods 6–A16 [variously 

paged]. 

Harbaugh, A.W., Banta, E.R., Hill, M.C., and McDonald, M.G., 2000, MODFLOW-2000, the U.S. 

Geological Survey modular ground-water model—User guide to modularization concepts and the 

ground-water flow process: U.S. Geological Survey Open-File Report 00–92, 121 p. 

Harder, A.H., Sauer, V.B., and Broussard, W.L., 1968, Water resources of the Lettsworth-InnisBatchelor area, Pointe Coupee Parish, Louisiana: Department of Conservation, Louisiana Geological 

Survey, and Louisiana Department of Public Works Water Resources Pamphlet 21, 28 p. 

Harris, G.D., 1904, Underground waters of southern Louisiana, with discussions of their uses for water 

supplies and for rice irrigation, by M.L. Fuller: U.S. Geological Survey Water-Supply Paper 101, 

98 p. 

Harris, G.D., 1906, Underground waters of southern Louisiana, pt. I of Geological Survey of Louisiana, 

report of 1905: Louisiana State Experiment Station, Louisiana Geological Survey Bulletin I, p. 1–77. 

Hill, M.C., and Tiedeman, C.R., 2007, Effective groundwater model calibration—With analysis of data, 

sensitivities, predictions, and uncertainty: Hoboken, N.J., Wiley, 455 p. 

Hsieh, P.A., and Freckleton, J.R., 1993, Documentation of a computer program to simulate horizontalflow barriers using the U.S. Geological Survey’s modular three-dimensional finite-difference groundwater flow model: U.S. Geological Survey Open-File Report 92–477, 32 p. 

Huntzinger, T.L., Whiteman, C.D., Jr., and Knochenmus, D.D., 1985, Simulation of ground-water 

movement in the “1,500- and 1,700-foot” aquifer of the Baton Rouge area, Louisiana: Louisiana 

Department of Transportation and Development, Office of Public Works Water Resources Technical 

Report no. 34, 52 p. 

Kazmann, R.G., 1970, The present and future ground-water supply of the Baton Rouge area: Baton 

Rouge, La., Louisiana State University, Louisiana Water Resources Research Institute Bulletin 5, 

44 p. 

Kernodle, J.M., and Philip, R.D., 1988, Using a geographic information system to develop a groundwater flow model: American Water Resources Association Monograph, series no. 14, p. 191–202. 

Keys, W.S., 1990, Borehole geophysics applied to ground-water investigations: U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 2, chap. E1, 150 p. 

Keys, W.S., and MacCary, L.M., 1971, Application of borehole geophysics to water-resources 

investigations: U.S. Geological Survey Techniques of Water-Resources Investigations, book 2, 

chap. E1, 126 p. 
31

Konikow, L.F., Hornberger, G.Z., Halford, K.J., and Hanson, R.T., 2009, Revised multi-node well 

(MNW2) package for MODFLOW ground-water flow model: U.S. Geological Survey Techniques 

and Methods 6–A30, 67 p. 

Kuniansky, E.L., 1989, Geohydrology and simulation of ground-water flow in the “400-foot,” 

“600-foot,” and adjacent aquifers, Baton Rouge area, Louisiana: Louisiana Department of 

Transportation and Development Water Resources Technical Report no. 49, 90 p. 

Kuniansky, E.L., Dial, D.C., and Trudeau, D.A., 1989, Maps of the “400-foot,” “600-foot,” and adjacent 

aquifers and confining beds, Baton Rouge area, Louisiana: Louisiana Department of Transportation 

and Development Water Resources Technical Report no. 48, 16 p. 

Langevin, C.D., Shoemaker, W.B., and Guo, Weixing, 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. 

Leake, S.A., and Lilly, M.R., 1997, Documentation of a computer program (FHB1) for assignment of 

transient specified-flow and specified-head boundaries in applications of the Modular FiniteDifference Ground-Water Flow Model (MODFLOW): U.S. Geological Survey Open-File Report 97–

571, 56 p. 

Long, R.A., 1965, Ground water in the Geismar-Gonzales area, Ascension Parish, Louisiana:

Department of Conservation, Louisiana Geological Survey, and Louisiana Department of Public 

Works Water Resources Bulletin 7, 67 p. 

Lovelace, J.K., 1991, Water use in Louisiana, 1990: Louisiana Department of Transportation and 

Development, Water Resources Special Report no. 6, 131 p. 

Lovelace, J.K., 2007, Chloride concentrations in ground water in East and West Baton Rouge Parishes, 

Louisiana, 2004–05: U.S. Geological Survey Scientific Investigations Report 2007–5069, 27 p. 

Lovelace, J.K., and Johnson, P.M., 1996, Water use in Louisiana, 1995: Louisiana Department of 

Transportation and Development Water Resources Special Report no. 11, 127 p. 

Lovelace, J.K., and Lovelace, W.M., 1995, Hydrogeologic unit nomenclature and computer codes for 

aquifers and confining units in Louisiana: Louisiana Department of Transportation and Development 

Water Resources Special Report no. 9, 12 p. 

Lurry, D.L., 1987, Pumpage of water in Louisiana, 1985: Louisiana Department of Transportation and 

Development, Office of Public Works Water Resources Special Report no. 4, 14 p. 

Marsily, Ghislain de, 1986, Quantitative Hydrogeology: San Diego, Calif., Academic Press, 440 p. 

Martin, Angel, Jr., and Whiteman, C.D., Jr., 1985a, Map showing generalized potentiometric surface of 

aquifers of Pleistocene Age, southern Louisiana, 1980: U.S. Geological Survey Water-Resources 

Investigations Report 84–4331, 1 sheet.

Martin, Angel, Jr., and Whiteman, C.D., Jr., 1985b, Map showing generalized potentiometric surface of 

the Evangeline and equivalent aquifers in Louisiana, 1980: U.S. Geological Survey Water-Resources 

Investigations Report 84–4359, 1 sheet. 

Martin, Angel, Jr., and Whiteman, C.D., Jr., 1990, Calibration and sensitivity analysis of a ground-water 

flow model of the coastal lowlands aquifer system in parts of Louisiana, Mississippi, Alabama, and 

Florida: U.S. Geological Survey Water-Resources Investigations Report 89–4189, 54 p. 

Martin, Angel, Jr., and Whiteman, C.D., Jr., 1991, Hydrology of the coastal lowlands aquifer system in 

parts of Alabama, Florida, Louisiana, and Mississippi: U.S. Geological Survey Open-File Report 91–

72, 115 p. 
32

Martin, Angel, Jr., and Whiteman, C.D., Jr., 1999, Hydrology of the coastal lowlands aquifer system in 

parts of Alabama, Florida, Louisiana, and Mississippi: U.S. Geological Survey Professional 

Paper 1416–H, 51 p. 

Martin, Angel, Jr., Whiteman, C.D., Jr., and Becnel, M.J., 1988, Generalized potentiometric surfaces of 

the upper and lower Jasper and equivalent aquifers in Louisiana, 1984: U.S. Geological Survey 

Water- Resources Investigations Report 87–4139, 2 sheets. 

McCulloh, R.P., 1991, Surface faults in East Baton Rouge Parish: Baton Rouge, La., Louisiana 

Geological Survey Open-File series 91–02, 25 p. 

Meyer, R.R., and Rollo, J.R., 1965, Saltwater encroachment, Baton Rouge area, Louisiana: Department 

of Conservation, Louisiana Geological Survey, and Louisiana Department of Public Works Water 

Resources Pamphlet 17, 9 p. 

Meyer, R.R., and Turcan, A.N., Jr., 1953, Summary report on the geology and ground-water resources 

of the Baton Rouge area, Louisiana: U.S. Geological Survey Open-File Report 53–192, 23 p. 

Meyer, R.R., and Turcan, A.N., Jr., 1955, Geology and ground-water resources of the Baton Rouge 

area, Louisiana: U.S. Geological Survey Water-Supply Paper 1296, 138 p. 

Morgan, C.O., 1961, Ground-water conditions in the Baton Rouge area, 1954-59, with special reference 

to increased pumpage: Department of Conservation, Louisiana Geological Survey, and Louisiana 

Department of Public Works Water Resources Bulletin 2, 78 p. 

Morgan, C.O., 1963, Ground-water resources of East Feliciana and West Feliciana Parishes, Louisiana:

Louisiana Department of Public Works, 58 p. 

Morgan, C.O., and Winner, M.D., Jr., 1964, Saltwater encroachment in aquifers of the Baton Rouge 

area—Preliminary report and proposal: Louisiana Department of Public Works, 37 p. 

Murray, G.E., 1961, Geology of the Atlantic and Gulf Coastal Province of North America: New York, 

Harper Brothers, 692 p. 

National Oceanic and Atmospheric Administration, 1995, Climatological data annual summary—

Louisiana: Asheville, N.C., Environmental Data Service, 23 p. 

Newcome, Roy, Jr., 1975, The Miocene aquifer system in Mississippi: U.S. Geological Survey WaterResources Investigations Report 46–75. 

Nyman, D.J., and Fayard, L.D., 1978, Ground-water resources of Tangipahoa and St. Tammany 

Parishes, southeastern Louisiana: Louisiana Department of Transportation and Development, Office 

of Public Works Water Resources Technical Report no. 15, 76 p. 

Orzol, L.L., 1997, User’s guide for MODTOOLS—Computer programs for translating data of 

MODFLOW and MODPATH into geographic information system files: U.S. Geological Survey 

Open-File Report 97–240, 86 p. 

Prakken, L.B., 2004, Louisiana ground-water map no. 17—Generalized potentiometric surface of the 

Kentwood aquifer system and the “1,500-foot” and “1,700-foot” sands of the Baton Rouge area in 

southeastern Louisiana, March-April 2003: U.S. Geological Survey Scientific Investigations Map 

2862, 2 sheets. 

Prakken, L.B., 2004, 2007, Chloride concentrations in the southern hills regional aquifer system in 

Livingston, southern Tangipahoa, and St. Tammany Parishes, Louisiana: Louisiana Department of 

Transportation and Development Water Resources Technical Report no. 76, 30 p. 

Roland, H.L., Hill, T.F., Autin, Peggy, Durham, C.O., and Smith, C.G., 1981, The Baton Rouge and 

Denham Springs-Scotlandville faults (mapping and damage assessment): Baton Rouge, La., Report 

prepared for the Louisiana Department of Natural Resources, Geological Survey and Durham 

Geological Associates Consultants, contract no. 21576-80-01, 26 p. 
33

Rollo, J.R., 1960, Ground water in Louisiana: Department of Conservation, Louisiana Geological 

Survey, and Louisiana Department of Public Works Water Resources Bulletin 1, 84 p. 

Rollo, J.R., 1960, 1969, Saltwater encroachment in aquifers of the Baton Rouge area, Louisiana: 

Department of Conservation, Louisiana Geological Survey, and Louisiana Department of Public 

Works Water Resources Bulletin 13, 45 p. 

Sargent, B.P., 2002, Water use in Louisiana, 2000: Louisiana Department of Transportation and 

Development Water Resources Special Report no. 15, 133 p. 

Sargent, B.P., 2007, Water use in Louisiana, 2005: Louisiana Department of Transportation and 

Development Water Resources Special Report no. 16, 133 p. 

Sargent, B.P., 2011, Water use in Louisiana, 2010: Louisiana Department of Transportation and 

Development Water Resources Special Report no. 17, 135 p. 

Saucier, R.T., 1994a, Geomorphology and Quaternary geologic history of the lower Mississippi Valley: 

Vicksburg, Miss., U.S. Army Corps of Engineers, v. 1, 364 p. 

Saucier, R. T., 1994b, Geomorphology and Quaternary geologic history of the lower Mississippi Valley:

Vicksburg, Miss., U.S. Army Corps of Engineers, v. 2. 

Smith, C.G., 1979, A geohydrologic survey of the “1,200-foot” aquifer in the Capital Area Ground 

Water Conservation District: Capital Area Ground Water Conservation Commission Bulletin 3, 19 p. 

Smith, C.G., and Kazmann, R.G., 1978, Subsidence in the Capital Area Ground Water Conservation 

District—An update: Baton Rouge, La., Capital Area Ground Water Conservation Commission 

Bulletin 2, 31 p. 

Smoot, C.W., 1986, Louisiana hydrologic atlas map no. 2—Areal extent of freshwater in major aquifers 

of Louisiana: U.S. Geological Survey Water-Resources Investigations Report 86–4150, 1 sheet. 

Smoot, C.W., 1988, Louisiana hydrologic atlas map no. 3—Altitude of the base of freshwater in 

Louisiana: U.S. Geological Survey Water-Resources Investigations Report 86–4314, 1 sheet.

Smoot, C.W., 1989, Louisiana hydrologic atlas map no. 4—Geohydrologic sections of Louisiana: U.S. 

Geological Survey Water-Resources Investigations Report 87–4288, 1 sheet. 

Snider, J.L., and Forbes, M.J., Jr., 1961, Pumpage of water in Louisiana, 1960: Louisiana Department of 

Public Works, Department of Conservation, and Louisiana Geological Survey, 6 p. 

Stuart, C.G., Knochenmus, Darwin, and McGee, B.D., 1994, Guide to Louisiana’s ground-water 

resources: U.S. Geological Survey Water-Resources Investigations Report 94–4085, 55 p. 

Tomaszewski, D.J., 1988, Ground-water hydrology of Livingston, St. Helena, and parts of Ascension 

and Tangipahoa Parishes, southeastern Louisiana: Louisiana Department of Transportation and 

Development Water Resources Technical Report no. 43, 54 p. 

Tomaszewski, D.J., 1996, Distribution and movement of saltwater in aquifers in the Baton Rouge area, 

Louisiana, 1990-92: Louisiana Department of Transportation and Development Water Resources 

Technical Report no. 59, 44 p. 

Tomaszewski, D.J., 1998, Hydrogeology and the effects of pumpage on the “1,500-foot” sand south of 

the Baton Rouge fault, near Brusly, Louisiana, 1996: Louisiana Department of Transportation and 

Development Water Resources Technical Report no. 65, 22 p. 

Tomaszewski, D.J., and Accardo, Darren, 2004, Louisiana ground-water map no. 19—Potentiometric 

surface of the “2,400-foot” sand of the Baton Rouge area, Louisiana, May-June 2002: U.S. Geological 

Survey Scientific Investigations Map 2865, 2 sheets. 

Tomaszewski, D.J., and Accardo, Darren, Louisiana Ground-water map no. 20—Potentiometric surface 

of the “2,000-foot” sand of the Baton Rouge area, Louisiana, May-June 2002: U.S. Geological Survey 

Scientific Investigations Map 2872, 2 sheets. 
34

Tomaszewski, D.J., and Anderson, M.L., 1995, Data from wells in a chloride monitoring network, 

Baton Rouge area, Louisiana, 1965-94: Louisiana Department of Transportation and Development 

Water Resources Basic Records Report no. 19, 40 p. 

Torak, L.J., and Whiteman, C.D., Jr., 1982, Applications of digital modeling for evaluating the groundwater resources of the “2,000-foot” sand of the Baton Rouge area, Louisiana: Louisiana Department 

of Transportation and Development, Office of Public Works Water Resources Technical Report no. 

27, 87 p. 

Turcan, A.N., Jr., 1966, Calculation of water quality from electrical logs—Theory and practice:

Department of Conservation, Louisiana Geological Survey, and Louisiana Department of Public 

Works Water Resources Pamphlet 19, 23 p. 

U.S. Census Bureau, 2010, Annual estimates of the population for counties of Louisiana—April 1, 

2000, to July 1, 2004 (CO-EST2004-01-22): accessed June 19, 2006, at 

http://www.census.gov/popest 

U.S. Environmental Protection Agency, 1977, National Secondary Drinking Water Regulations: Federal 

Register, v. 42, no. 62, pl. 143, p. 17143–17147. 

U.S. Environmental Protection Agency, 2006, 2006 edition of the drinking water standards and health 

advisories: Washington, D.C., U.S. Environmental Protection Agency, Office of Water, 12 p. 

Viewlog Systems, 2004, VIEWLOG borehole data management system: Toronto, Ontario, Canada, 

Viewlog Systems, 465 p. 

Walter, W.H., 1982, Pumpage of water in Louisiana, 1980: Louisiana Department of Transportation and 

Development, Office of Public Works Water Resources Special Report no. 3, 15 p. 

Walters, D.J., 1992, Louisiana ground-water map no. 5—Potentiometric surface, 1990, and water-level 

changes, 1974-90, of the Evangeline equivalent/southeast Louisiana aquifer system: U.S. Geological 

Survey Water-Resources Investigations Report 92–4112, 2 sheets. 

Walter, W.H., 1995, Louisiana ground-water map no. 7—Potentiometric surface, 1991, and water-level 

changes, 1969-91, of the Chicot equivalent aquifer system in southeastern Louisiana: U.S. Geological 

Survey Water-Resources Investigations Report 94–4202, 2 sheets. 

Whiteman, C.D., Jr., 1972, Ground water in the Plaquemine-White Castle area, Iberville Parish, 

Louisiana: Department of Conservation, Louisiana Geological Survey, and Louisiana Department of 

Public Works Water Resources Bulletin 16, 69 p. 

Whiteman, C.D., Jr., 1979, Saltwater encroachment in the “600-foot” and “1,500-foot” sands of the 

Baton Rouge area, Louisiana, 1966-78, including a discussion of saltwater in other sands: Louisiana 

Department of Transportation and Development, Office of Public Works Water Resources Technical 

Report no. 19, 49 p. 

Whiteman, C.D., Jr., 1980, Measuring local subsidence with extensometers in the Baton Rouge area, 

Louisiana, 1975-79: Louisiana Department of Transportation and Development, Office of Public 

Works Water Resources Technical Report no. 20, 18 p. 

Winner, M.D., Jr., 1963, The Florida Parishes—An area of large, undeveloped ground-water potential in 

southeastern Louisiana: Louisiana Department of Public Works, 50 p. 

Winner, M.D., Jr., Forbes, M.J., Jr., and Broussard, W.L., 1968, Water resources of Pointe Coupee 

Parish, Louisiana: Department of Conservation, Louisiana Geological Survey, and Louisiana 

Department of Public Works Water Resources Bulletin 11, 110 p. 

Zheng, Chunmiao, 2010, MT3DMS v. 5.3—Supplemental user’s guide: Tuscaloosa, Ala., University of 

Alabama, Department of Geological Sciences, 51 p.

Zheng, Chunmiao, and Bennett, G.D., 1995, Applied contaminant transport modeling: New York, Van 

Nostrand Reinhold, 440 p. 
35

Zheng, Chunmiao, and Wang, P.P., 1999, MT3DMS—A modular three-dimensional multispecies 

transport model for simulation of advection, dispersion and chemical reactions of contaminants in 

ground-water systems; documentation and user’s guide: Jacksonville, Fla., U.S. Army Corps of 

Engineers Contract Report SERDP-99-1, 221 p. 
Lake

Maurep

MISSISSIPPI

LOUISIANA

!!!!!

!!!

!

!!

!!

!

!

!!

!!!

!

!

!

!

!

!!

!

!

!

!

!

!

!!!! !! !

!

! !

!!

!

!

!

!

!! !

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!!!!

!

!!!!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!!

! !

!

!

!

!

!

!

!

!!

!

!

! !

!

!

!

!

!

!!

! !

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!!!

!

!

!

! !

!

!

!

!

! !

!!!!!!!!!!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!!!

!

!!

!!

!

!

!

! ! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!! !

!

!

!

!

!!

!!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

! !

!!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!! !

!

!

!

!

!

! !

!

!

!

!

!

!

! !

!

!

!

!

!!!

!

!

!

!

!

!!

!

!

!

!

!

! !

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

! !

! !

!

!

!

!

!

!

! !

!

!

!

!

!

! !

!

!

!

!

!

!

!

! !

!

!

!

! !

!! !

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

! ! !

!

!

!

!

!

!!

!

!

!

!

!

!!

!

!

!

!

!

! !

!

!

!

!

!

!!

! !

!

!

!

!

!

!

!

!

! !

! !

! !

!!

!

!!

!

!

!

!!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!!

!

!

!

! !

!

! !

!

!

!

!

!! !

! !

!

!

! !

!

! !

!

!

!

!

!

!

!

!

!

!

!

! ! ! ! !

!

!

!

! !

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

! !

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

! ! !

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

! ! !

!

!

!

!

! ! !

!

!

! !

West

Feliciana East Feliciana St. Helena

T

 Livingston East Baton Rouge

West

Baton

Rouge

Pointe

Coupee

Iberville

St. Martin Assumption

St. Landry

Avoyelles

Concordia

Wilkinson

Amite

BatonRouge

Breaux Bridge

Gonzales

Hammon

Adams Franklin 

Seefig. 10

A 

Figure 1. Location of study the area, the Baton Rouge Fault, geophysical-control wells, and simulatedgroundwater-withdrawal wells in southeastern Louisiana and southwestern Mississippi.

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15

190

55

12

10

61

61 10

61

55

51

190

71

51

98

0 10 20 KILO0 10 

92°00' 91°45' 91°30' 91°15' 91°00' 90°45' 90°30'

31°15'31°00'30°45'30°30'30°15'

See

A' fig. 2
VERTICAL SCALE IS GREATLY EXAGGERATEDDatum is National Geodetic Vertical Datum of 1929 (NGVD 29)

0 10 MILES0 10 KILOMETERS

-400

NGVD 29

-600-800

-1,000-1,200-1,400-1,600-1,800

200

-2,000-2.200-2,400-2,600-2,800-3,000-3,200-3,400-3,600-3,800

400

-200

FEET

“1,000-foot” sand

“1,700-foot” sand

“1,000-foot” sand

“1,500-foot” sand

“2,000-foot” sand

“1,500-foot” sand

“2,000-foot” sand

“2,800-foot” sand

“400-foot” sand

“2,400-foot” sand

“2,800-foot” sand

“1,700-foot” sand

“2,000-foot” sand

“2,400-foot” sand

“2,400-foot” sand

“1,200-foot” sand “1,200-foot” sand

Catahoula 

aquifer

“1,500-foot” sand

“1

“1,200-foot” sand

“1,000-foot” sand

“1,700-foot” sand

“600-foot” sand

“400-foot” 

sand

“600-foot” 

sand

“800-foot” 

sand

Shallow aquifer Shallow aquifer Shallow aquifer

“1

“40

“

“1,700-foot” sand

“

“2,000-foot” sand

“2,400-foot” sand

“2,400-foot” sand

“2,800-foot” sand

Catahoula 

aquifer

?

?

?

“2,800- foot” 

sand

?

?

?

?

?

?

? ?

“800-foot” 

sand

Upland terrace aquifer

“800-foot” 

sand

?

Mississippi River 

alluvial aquifer 

NORTH

A'

Figure 2. Hydrogeologic section A-A' in East Baton Rouge and East and West Feliciana Parishes, southeastern Louisiana. Figure modified from Griffith (2003).

Hydrogeologic framework layers—Shows the  location of hydrogeologic layers. Aquifer layers may  contain local confining beds. See figure 7 for conceptual diagram of hydrogeologic framework layers.

EXPLANATION

Hydrogeologic unit—Shows the  generalized location of the hydrogeologic  units. Layer 1—Mississippi River alluvial aquifer, shallow sands, upland terrace aquifer, and the “400-,” “600-,” and “800-foot” sands  terrace aquifersLayer 5—“1,500-foot” sandLayer 3—“1,000-” and “1,200-foot” sandsLayer 7—“1,700-foot” sandLayers 9 to 18—"2,000-foot" sandLayer 20—"2,400-foot" sandLayer 22—"2,800-foot" sand

BATON

ROUGE

GENERALIZED 

SURFACE PROFILE

FLOOD PLAIN 

BOUNDARIES

ST. FRANCISVILLE

W. FELICIANA PARISH

E. FELICIANA PARISH

E. FELICIANA PARISH

E. BATON ROUGE PARISH

TEPETATE 

FAULT

BATON R0UGE

FAULT

I-10 HWY 19

WF-236

WF-242

WF-267

WF-269

WF-246

WF-44

EB-833

EB-645

EB-1268

EB-534

EB-1028

FLOOD PLAIN 

BOUNDARIES

Index Map

ARKANSAS A R K A N S A S

MISSISSIPPI M I S S I S S I P P I

TEXAS 

GULF OF MEXICO G U L F O

F M

E X I

C O

LOUISIANA L O U I S I A N A

Study Area

Well—Shows name and location of well.Lithologic contact—Separates clay and sand  units. Dashed where approximate. Queried where  uncertain.

?

Hydrogeologic contact—defines boundary  between conjoined or merged aquifers.Fault

EB-534

Intervening confining unit layer

A

A'
Lake

Maurep

MISSISSIPPI

West LOUISIANA

Feliciana East Feliciana St. Helena

Ta

 Livingston East Baton Rouge West

Baton

Rouge

Pointe

Coupee

Iberville

St. Martin Assumption

St. Landry

Avoyelles

Concordia

Wilkinson

Amite

BatonRouge

Breaux Bridge

Gonzales

Hamm

Adams Franklin 

Figure 3. Simulated altitude of the top of the "1,500-foot" sand of the Baton Rouge area in southeastern Land southwestern Mississippi.

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15

0

-200

-800

-400

-600

-1800

-1000

-1200

-1400

-2000

-1600

200

-1200

-1800

-1400

0

-200

-800

-400

-600

-1800

-1000

-1200

-1400

-2000

-1600

200

-1200

-1800

-1400

0

-200

-800

-400

-600

-1800

-1000

-1200

-1400

-2000

-1600

200

-1200

-1800

-1400

190

55

12

10

61

61 10

61

55

51

190

71

51

98

0 10 20 KILO

0 10 

92°00' 91°45' 91°30' 91°15' 91°00' 90°45' 90°30'

31°15'31°00'30°45'30°30'30°15'
Lake

Maurep

MISSISSIPPI

West LOUISIANA

Feliciana East Feliciana St. Helena

Ta

 Livingston East Baton Rouge West

Baton

Rouge

Pointe

Coupee

Iberville

St. Martin Assumption

St. Landry

Avoyelles

Concordia

Wilkinson

Amite

BatonRouge

Breaux Bridge

Gonzales

Hamm

Figure 4. Simulated thickness of the "1,500-foot" sand of the Baton Rouge area in southeastern Louisiana southwestern Mississippi.

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15

190

55

12

10

61

61 10

61

55

51

190

71

51

98

0 10 20 KILO0 10 

92°00' 91°45' 91°30' 91°15' 91°00' 90°45' 90°30'

31°15'31°00'30°45'30°30'30°15'
Lake

Maure

MISSISSIPPI

LOUISIANA

W. Feliciana E. Feliciana St. Helena

Tan

 Livingston E. Baton Rouge

W. Baton

Rouge

Pointe

Coupee

Iberville

St. Martin Assumption

St. Landry

Avoyelles

Concordia

Wilkinson

Amite

BatonRouge

Breaux Bridge

Gonzales

Hammond

Adams Franklin 

Figure 5. Simulated altitude of the top of the "2,000-foot" sand of the Baton Rouge area in southeastern Land southwestern Mississippi.

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15

0

-400

-600

-200

-800

-1400

-1600

-1000

-2200

-2400

-1800

-2000

-2600

-1200

200

-2800

-3000

-2400

-2800

0

-400

-600

-200

-800

-1400

-1600

-1000

-2200

-2400

-1800

-2000

-2600

-1200

200

-2800

-3000

-2400

-2800

0

-400

-600

-200

-800

-1400

-1600

-1000

-2200

-2400

-1800

-2000

-2600

-1200

200

-2800

-3000

-2400

-2800

190

55

12

10

61

61 10

61

55

51

190

71

51

98

0 10 20 KILO

0 10 

92°00' 91°45' 91°30' 91°15' 91°00' 90°45' 90°30'

31°15'31°00'30°45'30°30'30°15'
Lake

Maurep

MISSISSIPPI

West LOUISIANA

Feliciana East Feliciana St. Helena

T

 Livingston East Baton Rouge West

Baton

Rouge

Pointe

Coupee

Iberville

St. Martin Assumption

St. Landry

Avoyelles

Concordia

Wilkinson

Amite

BatonRouge

Breaux Bridge

Gonzales

Ham

Adams Franklin 

Figure 6. Simulated thickness of the "2,000-foot sand of the Baton Rouge area in southeastern Louisianaand southwestern Mississippi.

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15

190

55

12

10

61

61 10

61

55

51

190

71

51

98

0 10 20 KILO

0 10 

92°00' 91°45' 91°30' 91°15' 91°00' 90°45' 90°30'

31°15'31°00'30°45'30°30'30°15'
Aquifer hydrologeologic units

LAYER 1—Mississippi River alluvial aquifer, shallow sands,

 upland terrace aquifer, and the “400-foot,” “600-foot,” and

 “800-foot” sands

LAYER 5—“1,500-foot” sand

LAYER 3—“1,000-foot” and “1,200-foot” sands

LAYER 7—“1,700-foot” sand

LAYERS 9 to 18—"2,000-foot" sand

LAYER 20—"2,400-foot" sand

LAYER 22—"2,800-foot" sand

Fault

Confining hydrogeologic units

NORTH

SOUTH

BATON ROUGE

DENHAM SPRINGSSCOTTLANDVILLE FAULT

BATON R0UGEFAULT

EXPLANATION

NOT TO SCALE

Figure 7. Conceptual offset of hydrogeologic units at faults in the Baton Rouge area, 

southeastern Louisiana.
Figure 8. Estimated withdrawals from the Baton Rouge sands, 1940-2007.

Year

1940 1950 1960 1970 1980 1990 

Annual withdrawal rate, in million gallons per day

0

1020304050

"400-foot" sand"600-foot" sand"800-foot" sand"1,000-foot" sand"1,200-foot" sand"1,500-foot" sand"1,700-foot" sand"2,000-foot" sand"2,400-foot" sand"2,800-foot" sand
MISSISSIPPI

West LOUISIANA

Feliciana East Feliciana St. Helena

Ta

 Livingston East Baton Rouge West

Baton

Rouge

Pointe

Coupee

Iberville

St. Martin Assumption

St. Landry

Avoyelles

Concordia

Wilkinson

Amite

BatonRouge

Breaux Bridge

Gonzales

Hamm

Adams Franklin L

Seefig. 10

Perimeter ofmodel domain

Figure 9. The model finite-difference grid and locations of the horizontal flow barrier in the "2,000-foot" 

Baton Rouge area and simulated groundwater-withdrawal wells in southeastern Louisiana and southweste

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: NAD 1983, UTM Zone 15

5

10

15

20

8085 5 10 75 80 85

1

1

0 10 20 KILO

0 10 

!!!!!

!!!

!

!!

!!

!

!

!!

!!!

!

!

!

!

!

!!

!

!!

!

!

!!!!! !! !

!

! !!!

!

!

!

!

!!

!! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!!!!

!

!!!!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!!

! !

!

!

!

!

!

!

!

!!

!

!

! !

!

!

!

!

!

!!

! !

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!!!

!

!

!

! !

!

!

!

!

!

!!!!!!!!!!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!!!

!

!!

!!

!

!

!

! ! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!! !

!

!

!

!

!!

!!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!! !

!

!

!

!

!

! !

!

!

!

!

!

!

! !

!

!

!

!

!!!

!

!

!

!

!

!!

!

!

!

!

!

! !

!

!

!

!

!

!

!!

!

!

!

!

!

!

!

! !

! !

!

!

!

!

!

!

! !

!

!

!

!

!

! !

!

!

!

!

!

!

!

! !

!

!

!

! !

!!

!

!! !!! 

!

!!

!

!

!

!

!

!

!

!

! ! !

!

!

!

!

!

!!

!

!

!

!

!

!!

!

!

!

!

!

! !

!

!

!

!

!

!!

! !

!

!

!

!

!

!

!

!

! !

! !

! !

!!

!

!!

!

!

!

!!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!!

!

!

!

!

!

!

! !

!

!

!

!

!! !

92°00' 91°45' 91°30' 91°15' 91°00' 90°45' 90°30'

31°15'31°00'30°45'30°30'30°15'
Mississippi River

12

10

61

10

190

110

19

1

37

30

67

76

986

110

10

986

73

1

25

3540

45

5055606570

7530

15 20 25 30 35 40 45 50 55 60 65 70

! !

!

!

!

!

!

!!

!!

!

!

!

! !

!

! !

!

!

!

!

!

!

! !

!

!

!!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!!

!!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

! !

!

!

!

!

!

!

!

! !

!

! !

!

!

!!

! !

!

!

!

!

!

!

!

!

!

! !!

!

!

!!

!!

!

!

!

!

!

! !

!

!

!

!

!

!

!

EB-1293

!

!

!

!

"

"

"

"

"

"

"

"

"

"

"

"

""

"

" "

"

"

EB - 944

EB - 794

WBR- 100B

EB - 806B

WBR- 147

WBR- 104

WBR- 37

WBR- 36

WBR- 5

EB - 946

EB - 327

EB - 323

EB - 301

EB - 299

EB - 298

EB - 146

EB - 117

EB - 28

EB - 782A

EB - 780A

WBR- 81

WBR- 100A

EB - 792A

012 0.5 KILOMETERS012 0.5 MILE

Figure 10. The 

finite-difference grid and locations of horizontal 

flow barriers, simulated groundwater-withdrawal w

and water-level observation wells in the "1,000-foot," "1,200-foot," "1,700-foot," "2,400-foot," and "2,800-foot" sanof the Baton Rouge area in the detailed model area in southeastern Louisiana.

91°12'30" 91°10'00" 91°07'30"

30°30'00"30°27'30"30°25'00"

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15

Government Street pumping station

Lafayette Street pumping station
EXPLANATION

 

Row

79

Row

16

11.35 miles

VERTICAL EXAGGERATION x10

Baton Rouge Fault Aquifer

Confining unit

Figure 11. North-to-south cross section along model column 24 showing aquifers, confining units, and finite-differencediscretization. The location of column 24 is shown on figure 10.

2,700 feet

Layer 1

Layer 22

North South

Cells other than red or blue containboth aquifers and confining units
Mississippi River Mississippi River

12

10

61

10

190

110

19

1

37

30

67

76

986

110

10

986

73

1

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

WBR-97

WBR-33

EB-972

EB-939

EB-884

EB-855

EB-813

EB-807

EB-806

EB-794

EB-790

EB-789

EB-783

EB-778

EB-751

EB-674

EB-534

EB-514

EB-378

EB-133

WBR-128

WBR-111

WBR-104

WBR-103

WBR-100 EB-1253 EB-1252

EB-1028

P136823

91°12'30" 91°10'00" 91°07'30"

30°30'00"30°27'30"30°25'00"

012 0.5 KILOMETERS012 0.5 MILE

Figure 12A. Pilot point locations and simulated horizontal hydraulic conductivity distribution within the "1,500-fooof the Baton Rouge area in the detailed model area in southeastern Louisiana.

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15
Mississippi River

12

10

61

10

190

110

19

1

37

30

67

76

986

110

10

986

73

1

!

! !

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

WBR-97

WBR-33

EB-972

EB-939

EB-884

EB-855

EB-813

EB-807

EB-806

EB-794

EB-790

EB-789

EB-783

EB-778

EB-751

EB-674

EB-534

EB-514

EB-378

EB-133

WBR-128

WBR-111

WBR-104

WBR-103

WBR-100 EB-1253 EB-1252

EB-1028

P136823

91°12'30" 91°10'00" 91°07'30"

30°30'00"30°27'30"30°25'00"

012 0.5 KILOMETERS012 0.5 MILE

Figure 12B. Pilot point locations and simulated horizontal hydraulic conductivity distribution within the "2,000-fooof the Baton Rouge area in the detailed model area in southeastern Louisiana.

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15
-90

-80-70-60-50-40-30-20-10

0

102030405060708090

-300 -200 -100 0 100 

Residual, in feet

Simulated water level alƟtude, in feet

Figure 13. Residuals as a function of simulated water-level altitudes for the “2,000-foot” sand of the Baton Rougsimulated aquifers. Residuals are calculated by subtracting simulated water-level altitudes from observed water-

Other aquif

“2000-foot
Lake

Maurep

MISSISSIPPI

West LOUISIANA

Feliciana East Feliciana St. Helena

Ta

 Livingston East Baton Rouge West

Baton

Rouge

Pointe

Coupee

Iberville

St. Martin Assumption

St. Landry

Avoyelles

Concordia

Wilkinson

Amite

BatonRouge

Breaux Bridge

Gonzales

Ham

Adams Franklin 

Figure 14. Simulated steady-state water levels within the "1,500-foot" sand of the Baton Rouge area reprepredevelopment conditions before 1940 in southeastern Louisiana and southwestern Mississippi.

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15

190

55

12

10

61

61 10

61

51

190

71

51

98

0 10 20 KILO

0 10 

Amite

Wilkinson

61

Concordia C

MISSISSIPPI

W n

yelles

Coupee

190

90 110 120

80 100

130

140

150 160

170

180

190

70

4 200 060

50

210 30 220

230

60

130

90

190

70

190 160

80

140

50

150

80

170 180

80

100

70

90 110 120

80 100

130

140

150 160

170

180

190

70

4 200 060

50

210

30

220

230

60

130

90

190

70

190 160

80

140

50

150

80

170

180

80

100

70

90 110 120

80 100

130

140

150 160

170

180

190

70

4 200 060

50

210

30

220

230

60

130

90

190

70

190 160

80

140

50

150

80

170

180

80

100

70

92°00' 91°45' 91°30' 91°15' 91°00' 90°45' 90°30'

31°15'31°00'30°45'30°30'30°15'
Lake

Maurep

MISSISSIPPI

West LOUISIANA

Feliciana East Feliciana St. Helena

T

 Livingston East Baton Rouge West

Baton

Rouge

Pointe

Coupee

Iberville

St. Martin Assumption

St. Landry

Avoyelles

Concordia

Wilkinson

Amite

BatonRouge

Breaux Bridge

Gonzales

Ham

Adams Franklin 

92°00' 91°45' 91°30' 91°15' 91°00' 90°45' 90°30'

31°15'31°00'30°45'30°30'30°15'

Figure 15. Simulated steady-state water levels within the "2,000-foot" sand of the Baton Rouge area reprepredevelopment conditions before 1940 in southeastern Louisiana and southwestern Mississippi.

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15

190

55

12

10

61

61 10

61

55

51

190

71

51

98

0 10 20 KILO

0 10 

90

150

140

160

130

80

100

120

110

170

180

70

190 200

60

210

220

230

240

260 250

270

280 290 50 300 310 320 330 340 360 350 370 40

90

150

140

160

130

80

100

1

2

0

110

170

180

70

190 200

60

210

220

230

240

260 250

270

280 290 50 300 310

320 330

340 360 350 370 40

90

150

140

160

130

80

100

1

2

0

110

170

180

70

190 200

60

210

220

230

240

260 250

270

280 290 50 300 310

320 330

340 360 350 370 40
Lake

Maurep

MISSISSIPPI

West LOUISIANA

Feliciana East Feliciana St. Helena

T

 Livingston East Baton Rouge West

Baton

Rouge

Pointe

Coupee

Iberville

St. Martin Assumption

St. Landry

Avoyelles

Concordia

Wilkinson

Amite

BatonRouge

Breaux Bridge

Gonzales

Ham

Adams Franklin 

Figure 16A. Simulated 2007 water levels within the "1,500-foot" sand of the Baton Rouge area in southeaLouisiana and southwestern Mississippi.

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15

190

55

12

10

61

61 10

61

51

190

71

51

98

0 10 20 KILO

0 10 

!

!

!

!

!! ! !

!

!!!!

!

!

!

!

!

!

!!

PC-39 EF-27

WBR-23

TA-454

LI-26B

B-918

EB-917

EB-652

EB-58

EB-392

B-168

-9

EB-803A

Amite

Wilkinson

61

Concordia C

MISSISSIP

W n

oyelles

Coupee

190

0 60

20

-4

0

-20 120

140

160

-60 -80

180

-100

200240

-12

0

0

-40

-20

120

140

60

40

80

40 20

-2

0

100

0

0 60

20

-40

-20 120

140

160

-60 -80

180

-100

200240

-120

0

-40

-20

120

140

60

40

80

40 20

-20

100

0

0 60

20

-4

0

-20 120

140

160

-60 -80

180

-100

200240

-12

0

0

-40

-20

120

140

60

40

80

40 20

-2

0

100

0

92°00' 91°45' 91°30' 91°15' 91°00' 90°45' 90°30'

31°15'31°00'30°45'30°30'30°15'
Mississippi River

12

10

61

10

190

19

1

37

30

67

76

986

110

10

986

73

1

012 0.5 KILOMETERS012 0.5 MILE

Figure 16B. Simulated 2007 water levels within the "1,500-foot" sand of the Baton Rouge area in the detailed modein southeastern Louisiana.

1 986

M

986

sippi

Riiv

!

!

!

!

!

!

!

!

!

!

!

!

EB-918

EB-917

EB-168

WBR-173

WBR-132

WBR-97B

EB-1293

EB-807A

EB-783A EB-789B

EB-782B

EB-780B

-95

-100

-105

-110

-115

-90

-125

-120

-85

-60

-65

-70 -75

-80

-130

-55

-135

-140

-95

-110 -115

-90

-120

-1

00

-105 -125

-85

-95

-100

-105

-110

-115

-90

-125

-120

-85

-60

-65

-70 -75

-80

-130

-55

-135

-140

-95

-110 -115

-90

-120

-100

-105 -125

-85

-95

-100

-105

-110

-115

-90

-125

-120

-85

-60

-65

-70 -75

-80

-130

-55

-135

-140

-95

-110 -115

-90

-120

-1

00

-105 -125

-85

91°12'30" 91°10'00" 91°07'30"

30°30'00"30°27'30"30°25'00"

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15
Lake

Maurep

MISSISSIPPI

West LOUISIANA

Feliciana East Feliciana St. Helena

T

 Livingston East Baton Rouge West

Baton

Rouge

Pointe

Coupee

Iberville

St. Martin Assumption

St. Landry

Avoyelles

Concordia

Wilkinson

Amite

BatonRouge

Breaux Bridge

Gonzales

Ham

Adams Franklin 

Figure 17A. Simulated 2007 water levels within the "2,000-foot" sand of the Baton Rouge area in southeaand southwestern Mississippi.

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15

190

55

12

10

61

61 10

61

55

51

190

71

51

98

0 10 20 KILO

0 10 

40

0

60

80

20

100

120

140

160

180

200

-20

220

240

260 280

-40

-60

300

320

-80

340

-1

00

-120

360

-

140 -160

-180

-200 !!

!

!

!

!

!

!! ! !

!

!!

! ! !! !

!

!

!

!

!

!

!

!

!

!

WF-40

PC-66

LI-61 LI-55

LI-54

IB-29

EB-90

WBR-50

WBR-10

TA-343

TA-273

TA

PC-144

PC-138

EB-781

EB-778

EB-575

EB-315

EB-304

WBR-111 EB-807BEB-803B

92°00' 91°45' 91°30' 91°15' 91°00' 90°45' 90°30'

31°15'31°00'30°45'30°30'30°15'

EB-322
Mississippi River

12

10

61

10

190

110

19

1

37

30

67

76

986

110

10

986

73

1

012 0.5 KILOMETERS012 0.5 MILE

Figure 17

B. Simulated 2007 water levels within the "2,000-foot sand of the Baton Rouge area in the detailed model 

in southeastern Louisiana.

-140

-155

-150

-145

-175

-170

-165

-160

-185

-180

-190

-195

-200

-135

-205

-210

-130

-215

-220

-125

-225

-190

-185

-195

-195

-190

-190

-225

-225

-140

-155

-150

-145

-175

-170

-165

-160

-185

-180

-190

-195

-200

-135

-205

-210

-130

-215

-220

-125

-225

-190

-185

-195

-195

-190

-190

-225

-225

-140

-155

-150

-145

-175

-170

-165

-160

-185

-180

-190

-195

-200

-135

-205

-210

-130

-215

-220

-125

-225

-190

-185

-195

-195

-190

-190

-225

-225

!

!

!

!

!

!

!

!

!

!!

!

!

EB-90

WBR-50

WBR-10

EB-781

EB-778

EB-367

EB-112

WBR-111

WBR-106

EB-1028

EB-807B

EB-792B

EB-783B

91°12'30" 91°10'00" 91°07'30"

30°30'00"30°27'30"30°25'00"

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15
100

-100

-60

-20

20

60

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

100

-100

-60

-20

20

60

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

100

-100

-60

-20

20

60

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

50

-150

-110

-70

-30

10

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

100

-100

-60

-20

20

60

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated

Figure 18. Simulated and observed water levels within the “1,000-foot” and “1,200-foot” sands of the

Baton Rouge area in southeastern Louisiana (see fig. 10 for well locations).

A. well EB-146

B. well EB-299

C. well EB-301

D. well EB-327

E. well EB-782A

Water-level altitude, in feet

Year
-20

-120

-100

-80

-60

-40

1960 1970 1980 1990 2000

-20

-120

-100

-80

-60

-40

1960 1970 1980 1990 2000

-40

-140

-120

-100

-80

-60

1960 1970 1980 1990 2000

-20

-120

-100

-80

-60

-40

1960 1970 1980 1990 2000

-20

-120

-100

-80

-60

-40

1960 1970 1980 1990 2000

Figure 19. Simulated and observed water levels within the “1,500-foot” sand of the Baton Rouge area in

southeastern Louisiana (see fig. 16B for well locations).

A. well EB-782B

B. well EB-807A

C. well EB-917

D. well EB-918

E. well EB-1293

Water-level altitude, in feet

Year

Observed

Simulated

MNW2 simulation

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated
Figure 20. Simulated and observed water levels within the “1,700-foot” sand of the Baton Rouge area in

southeastern Louisiana (see fig. 10 for well locations).

A. well EB-792A

B. well WBR-81

C. well WBR-100A

Water-level altitude, in feet

Year

Observed

Simulated

Observed

Simulated

Observed

Simulated

10

-90

-70

-50

-30

-10

1950 1960 1970 1980 1990 2000

-110

-130

140

40

60

80

100

120

1950 1960 1970 1980 1990 2000

20

0

0

-100

-80

-60

-40

-20

1950 1960 1970 1980 1990 2000

-120

-140
1920 1930 1940 1950 1960 1970 1980 1990 2000

100

-220

-180

-20

20

160

-260

-300

-60

-100

-140

1920 1930 1940 1950 1960 1970 1980 1990 2000

120

-200

-160

0

40

80

-240

-280

-40

-80

-120

1920 1930 1940 1950 1960 1970 1980 1990 2000

80

-240

-200

-40

00

40

-280

-320

-80

-120

-160

1920 1930 1940 1950 1960 1970 1980 1990 2000

140

-180

-140

20

60

100

-220

-260

-20

-60

-100

1920 1930 1940 1950 1960 1970 1980 1990 2000

140

-180

-140

20

60

100

-220

-260

-20

-60

-100

Figure 21. Simulated and observed water levels within the “2,000-foot” sand of the Baton Rouge area

in southeastern Louisiana (see fig. 17B for well locations).

A. well EB-90

B. well EB-112

C. well EB-367

D. well EB-781

E. well EB-792B

Water-level altitude, in feet

Year

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated
Figure 21. Simulated and observed water levels within the “2,000-foot” sand of the Baton Rouge area in

southeastern Louisiana (see fig. 17B for well locations)—Continued.

F. well EB-807B

G. well WBR-10

H. well WBR-50

I. well WBR-111

teef ni ,edutitla level-retaW

Year

Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated

1920 1930 1940 1950 1960 1970 1980 1990 2000

200

-120

-80

80

120

160

-160

-200

40

0

-40

1920 1930 1940 1950 1960 1970 1980 1990 2000

60

-260

-220

-60

-20

20

-300

-340

-100

-140

-180

1920 1930 1940 1950 1960 1970 1980 1990 2000

200

-120

-80

80

120

160

-160

-200

40

0

-40

1920 1930 1940 1950 1960 1970 1980 1990 2000

0

-320

-280

-120

-80

-40

-360

-400

-160

-200

-240
Observed

Simulated

Observed

Simulated

Observed

Simulated

Observed

Simulated

Figure 22. Simulated and observed water levels within the “2,400-foot” sand of the Baton Rouge area in

southeastern Louisiana (see figs. 10 and 17A for well locations).

A. well EB-322

B. well EB-794

C. well EB-806B

D. well WBR-100B

Water-level altitude, in feet

1960 1970 1980 1990 2000

0

-160

-40

-200

-80

-120

1960 1970 1980 1990 2000

-40

-200

-80

-240

-120

-160

1960 1970 1980 1990 2000

0

-160

-40

-200

-80

-120

1960 1970 1980 1990 2000

100

-60

60

-100

20

-20
Figure 23. Simulated and observed water levels within the “2,800-foot” sand of the Baton Rouge area

southeastern Louisiana (see fig. 10 for well location).

A. well EB-944

Water-level altitude, in feet

Year

Observed

Simulated

1960 1970 1980 1990 2000

40

-20

-10

0

20

30

10
10

-10

30507090

110130150170

1940 1950 1960 1970 1980 1990 

Million gallons per day

Year

EXPLANATION

Figure 24. Simulated groundwater withdrawals and flows from storage and specified-head boundaries.

Simulated groundwater withdrawalsNet flow from storageNet flow from specified-head boundaries
C. well EB-1028

D. well EB-1150

A. well EB-781

Observed

Simulated row 73

Simulated row 72

Year

E. well EB-630

B. well EB-807B

Observed

Simulated

Figure 25. Simulated and observed chloride concentrations at observation wells within the

“2,000-foot” sand of the Baton Rouge area in southeastern Louisiana (see fig. 26 for well

locations). Chloride concentration, in milligrams per liter

Observed

Simulated

Observed

Simulated

Observed

Simulated

1960 1970 1980 1990 2000

500

0

100

200

300

400

1960 1970 1980 1990 2000

500

0

100

200

300

400

1960 1970 1980 1990 2000

500

0

100

200

300

400

1960 1970 1980 1990 2000

500

0

100

200

300

400

1960 1970 1980 1990 2000

0

1,000

2,000

3,000
Mississippi River

12

10

61

10

190

110

19

1

37

30

67

76

986

110

10

986

73

1

91°12'30" 91°10'00" 91°07'30"

30°30'00"30°27'30"30°25'00"

012 0.5 KILOMETERS012 0.5 MILE

Figure 26. Simulated 2007 water levels and chloride concentrations at the base of the "2,000-foot" sand of theBaton Rouge area in the detailed model area in southeastern Louisiana.

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

.

.

.

.

.

.

EB-781

EB-X

EB-807B

EB-1028

EB-630 EB-1150

EB-874

-140

-

155

-150

-145

-175

-

170

-

1

65

-

1

60

-185

-180

-190

-195

-200

-135

-205

-210 -130 -215

-220 -125 -225

-190

-185 -195

-195

-190

-190

-225

-225

-140

-155

-150

-145

-175

-170

-165

-160

-185

-180

-190

-195

-200

-135

-205

-210 -130 -215

-220 -125 -225

-190

-185 -195

-195

-190

-190

-225

-225

-140

-

155

-150

-145

-175

-

170

-

1

65

-

1

60

-185

-180

-190

-195

-200

-135

-205

-210 -130 -215

-220 -125 -225

-190

-185 -195

-195

-190

-190

-225

-225

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15
Mississippi River

12

10

61

10

190

19

1

37

30

67

76

986

110

10

986

73

1

012 0.5 KILOMETERS012 0.5 MILE

Figure 27. Predicted 2047 water-levels within the "1,500-foot" sand of the Baton Rouge area in the detailed modelarea in southeastern Louisiana after continued pumping at 2007 rates.

1 986

M

986

ippi

Riiv

-110

-105

-100

-11

5

-120

-95

-125 -130

-90

-135

-65

-70

-75 -80

-85

-60

-140

-145

-110-120

-115

-95

-125

-105

-100

-130

-90

-110

-105

-100

-115

-120

-95

-125 -130

-90

-135

-65

-70

-75 -80

-85

-60

-140

-145

-110-120

-115

-95

-125

-105

-100

-130

-90

-110

-105

-100

-11

5

-120

-95

-125 -130

-90

-135

-65

-70

-75 -80

-85

-60

-140

-145

-110-120

-115

-95

-125

-105

-100

-130

-90

!

!

!

!

!

!

!

!

!

!

!

!

EB-918

EB-917

EB-168

WBR-173

WBR-132

WBR-97B

EB-1293

EB-807A

EB-783A EB-789B

EB-782B

EB-780B

91°12'30" 91°10'00" 91°07'30"

30°30'00"30°27'30"30°25'00"

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15
Mississippi River

12

10

61

10

190

110

19

1

37

30

67

76

986

110

10

986

73

1

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

-210

-160

-170

-1

65

-1

90

-185

--175 180 -195

-200

-205

-215

-155 -220 -225-150 -230 -235 -145 -240

-245

-205 -215

-210

-215 -205

-240

-210

-160

-170

-165

-190

-185

--175 180 -195

-200

-205

-215

-155 -220 -225-150 -230 -235 -145 -240

-245

-205 -215

-210

-215 -205

-240

-210

-160

-170

-1

65

-1

90

-185

--175 180 -195

-200

-205

-215

-155 -220 -225-150 -230 -235 -145 -240

-245

-205 -215

-210

-215 -205

-240

91°12'30" 91°10'00" 91°07'30"

30°30'00"30°27'30"30°25'00"

012 0.5 KILOMETERS012 0.5 MILE

Figure 28. Predicted 2047 water levels and chloride concentrations at the base of the "2,000-foot" sand of theBaton Rouge area in the detailed model area in southeastern Louisiana after continued pumping at 2007 rates.

.

.

.

.

.

EB-781

EB-807B

EB-1028

EB-630 EB-1150

EB-874 .

EB-X

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15
Chloride concentration, in milligrams per liter

A well EB-1028

B well EB-1150

D well EB-781

1960 1970 1980 1990 2000 2010 2020 2030 2040

E well EB-807B

Figure 29. Predicted chloride concentrations at the base of the “2,000-foot” sand after continued pumping at 2007 rates (scen

(scenario 3), 3.6 Mgal/d (million gallons per day) reduction of industrial-district withdrawals (scenario 4), and cessation of in

from the “2,000-foot” sand (scenario 5) for: A. well EB-1028;

B. well EB-1150;

C. well EB-630;

D. well EB-781;

E. well EB

well EB-X (see fig. 26 for well locations).

bserved

enario 1: status quo

Scenario3a: scavenger well in row 57 and column 26 

Scenario 3b: scavenger well in row 68 and column 30 

Scenario 4: 3.6 Mgal/d reductio he indu al 

Scenario 5: industrial- cessation

bserved

enario 1

Scenario3

Scenario 3Scenario 4

Scenario 5

bserved

enario 1: status quo

Scenario3a: scavenger well in row 57 and column 26 

Scenario 3b: scavenger well in row 68 and column 30 Scenario 4: 3.6 Mgal/d reductio he indu al 

Scenario 5: industrial- cessation

bserved

enario 1: status quo

Scenario3a: scavenger well in row 57 and column 26 

Scenario 3b: scavenger well in row 68 and column 30Scenario 4: 3.6 Mgal/d reductio he indu al 

Scenario 5: industrial- cessation

bserved

enario 1

Scenario3a

Scenario 3Scenario 4

Scenario 5

bserved

enario 1: status quo

Scenario3a: scavenger well in row 57 and column 26 Scenario 3b: scavenger well in row 68 and column 30 

Scenario 4: 3.6 Mgal/d reductio he indu al 

Scenario 5: industrial- cessation

Chloride concentration, in milligrams per liter

Chloride concentration, in milligrams per liter

Chloride concentration, in milligrams per liter

Chloride concentration, in milligrams per liter

Chloride concentration, in milligrams per liter

Year 

Year Year

Year

0

100

200300

400500

1960 1970 1980 

0

200400600

800

1,000

1960 1970 1980 1990 2000 2010 2020 2030 2040 0

1,000

1960 1970 1980 1990 2000 2010 2020 2030 2040

2,000

3,000

4,000

0

100

200

300

400500

1960 1970 1980 

0

100

200300400500

1960 1970 1980 1990 2000 2010 2020 2030 2040

0

200

400

600

800

1,000

1960 1970 1980 1990 2000 2010 2020 2030 2040

1,200

1,4001,6001,800

2,0002,200
Mississippi River

12

10

61

10

190

19

1

37

30

67

76

986

110

10

986

73

1

012 0.5 KILOMETERS012 0.5 MILE

Figure 30. Predicted 2047 water levels within the "1,500-foot" sand of the Baton Rouge area in the detailed model ain southeastern Louisiana following cessation of pumping from selected industrial wells in the "1,500-foot" and"1,700-foot" sands after 2007.

1 986

Missis

986 ssippi 

Rive

!

!

!

!

!

!

!

!

!

!

!

!

EB-918

EB-917

EB-168

WBR-173

WBR-132

WBR-97B

EB-1293

EB-807A

EB-789B EB-783A

EB-782B

EB-780B

-90

-85

-95

-100 -80

-105

-110 -115

-75

-55

-60

-65

-70

-120

-50

-125

-130

-90

-80

-85

-100 -105

-75

-95

-110

-70

-90

-85

-95

-100 -80

-105

-110 -115

-75

-55

-60

-65

-70

-120

-50

-125

-130

-90

-80

-85

-100 -105

-75

-95

-110

-70

-90

-85

-95

-100 -80

-105

-110 -115

-75

-55

-60

-65

-70

-120

-50

-125

-130

-90

-80

-85

-100 -105

-75

-95

-110

-70

91°12'30" 91°10'00" 91°07'30"

30°30'00"30°27'30"30°25'00"

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15
Mississippi River

12

10

61

10

190

110

19

1

37

30

67

76

986

110

10

986

73

1

012 0.5 KILOMETERS012 0.5 MILE

Figure 31. Predicted 2047 water levels and chloride concentrations at the base of the "2,000-foot" sand of theBaton Rouge area in the detailed model area in southeastern Louisiana after 40 years of pumping at a rate of 2 million gallons per day from a simulated scavenger well located in model row 57 and column 26.

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

.

.

.

.

.

EB-781

EB-807B

EB-1028

EB-630 EB-1150

.

EB-X

EB-874

-225

-165 -180

-170

-175 -200

-1

95

-185

-1

90

-215-205

-210

-220

-230

-235

-160

-240

-245-250 -155 -150 -255

-235

-225

-220

-230

-220

-255

-255

-225

-165 -180

-170

-175 -200

-195 -185

-190

-215-205

-210

-220

-230

-235

-160

-240

-245-250 -155 -150 -255

-235

-225

-220

-230 -220

-255

-255

-225

-165 -180

-170

-175 -200

-1

95

-185

-1

90

-215-205

-210

-220

-230

-235

-160

-240

-245-250 -155 -150 -255

-235

-225

-220

-230

-220

-255

-255

91°12'30" 91°10'00" 91°07'30"

30°30'00"30°27'30"30°25'00"

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15
Mississippi River

12

10

61

10

190

110

19

1

37

30

67

76

986

110

10

986

73

1

012 0.5 KILOMETERS012 0.5 MILE

Figure 32. Predicted 2047 water levels and chloride concentrations at the base of the "2,000-foot" sand of theBaton Rouge area in the detailed model area in southeastern Louisiana after 40 years of pumping at a rate of2 million gallons per day from a simulated scavenger well located in model row 68 and column 30.

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

.

.

.

.

.

EB-781

EB-807B EB-1028

EB-630

EB-1150

.

EB-X

EB-874

-170 -

1

85

-1

80

-175

-205

-200

-

195

-190

-215

-210

-220

-225

-230

-165

-235 -160

-240

-245 -250 -155

-150 -255

-235

-230

-255

-230

-225

-220

-255 -170 -185

-180

-175

-205 -200

-195

-190

-215

-210

-220

-225

-230

-165

-235 -160

-240

-245 -250 -155

-150 -255

-235

-230

-255

-230

-225

-220

-255 -170 -185

-1

80

-175

-205

-200

-

195

-190

-215

-210

-220

-225

-230

-165

-235 -160

-240

-245 -250 -155

-150 -255

-235

-230

-255

-230

-225

-220

-255 

91°12'30" 91°10'00" 91°07'30"

30°30'00"30°27'30"30°25'00"

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15
Mississippi River

12

10

61

10

190

110

19

1

37

30

67

76

986

110

10

986

73

1

012 0.5 KILOMETERS012 0.5 MILE

Figure 33. Predicted 2047 water levels and chloride concentrations at the base of the "2,000-foot" sand of theBaton Rouge area in the detailed model area in southeastern Louisiana after a 3.6 million gallon per day reductionin pumping (from 2007 rates) at selected wells in the Baton Rouge industrial district.

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

.

.

.

.

.

EB-781

EB-807B

EB-1028

EB-630

EB-1150

.

EB-X

EB-874 -185

-155

-175

-150

-145

-

170

-165

-160

-180

-140

-190

-195

-135 -200

-130 -205-210

-185

-180

-185

-180

-190

-205

-210

-185

-155

-175

-150

-145

-170 -165

-160

-180

-140

-190

-195

-135 -200

-130 -205-210

-185

-180

-185

-180

-190

-205

-210

-185

-155

-175

-150

-145

-

170

-165

-160

-180

-140

-190

-195

-135 -200

-130 -205-210

-185

-180

-185

-180

-190

-205

-210

91°12'30" 91°10'00" 91°07'30"

30°30'00"30°27'30"30°25'00"

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15
Mississippi River

12

10

61

10

190

110

19

1

37

30

67

76

986

110

10

986

73

1

012 0.5 KILOMETERS012 0.5 MILE

Figure 34. Predicted 2047 water levels and chloride concentrations at the base of the "2,000-foot" sand of theBaton Rouge area in the detailed model area in southeastern Louisiana following cessation of pumping from the2000-ft sand in the Baton Rouge industrial district after 2007.

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!

!!

!

!

!

!

!

!

.

.

.

.

.

EB-781

EB-807B

EB-1028

EB-630 EB-1150

.

EB-X

EB-874

-90

-85

-95

-100

-105

-80

-110

-75

-115

-90

-11-1 0 10

-85

-90

-85

-95

-100

-105

-80

-110

-75

-115

-90

-11-1 0 10

-85

-90

-85

-95

-100

-105

-80

-110

-75

-115

-90

-11-1 0 10

-85

91°12'30" 91°10'00" 91°07'30"

30°30'00"30°27'30"30°25'00"

Base map modified from Louisiana Oil Spill Coordinator, Office of the

Governor, Louisiana GIS CD: A Digital Map of the State, Version 2.0Map Projection: North American Datum of 1983, Universal Transverse Mercator Zone 15
Rice General

East Baton Rouge 75.12 66.22 7.79 0.28 0.19 0.00 0.25 0.04 149.89 

East Feliciana 3.00 .03 .00 .27 .02 .00 .18 .00 3.50 

Pointe Coupee 4.08 4.92 1.89 .23 .10 4.78 7.19 4.34 27.53 

West Baton Rouge 7.21 1.50 .00 .05 .03 .00 .35 1.07 10.21 

West Feliciana 4.15 .41 .02 .10 .00 .00 .00 .00 4.68 

Total 93.56 73.08 9.70 .93 .34 4.78 7.97 5.45 195.81 

Table 1. Groundwater withdrawals (in million gallons per day) in the Baton Rouge area, Louisiana, by parish 

and principal use, 2010 (modified from Sargent, 2011).

Parish

Public

supply Industrial

Power 

generation Total use

Rural 

domestic Livestock

Irrigation Aquaculture
?

?? ?

Oligocene

Miocene

Tertiary Quaternary Pleistocene Pliocene

Catahoula  aquifer system

equivalent 

Jasper equivalent  aquifer system

Evangeline equivalent  aquifer systemChicot equivalent  aquifer system

Southern Hills regional aquifer system

Catahoula  formationHattiesburg  formationCitronelle  formationGraham  ferry  formationPascagoula  formation

Holocene Alluvium Near-surface aquifers

System Series

Aquifer system

1 Aquifer

unit

Southern 

Mississippi

Franklinton aquifer

Tchefuncte aquiferHammond aquiferAmite aquiferRamsay aquiferLower Ponchatoula  aquiferBig Branch aquiferKentwood aquiferAbita aquiferCovington aquiferSlidell aquifer

Upland terrace aquiferUpper Ponchatoula  aquifer

Catahoula aquifer

“2,000-foot” sand“2,400-foot” sand“2,800-foot” sand

“800-foot” sand

“1,000-foot” sand“1,200-foot” sand“1,500-foot” sand“1,700-foot” sand

“600-foo“400-foo

Upland terrace

aquifer

No regionally extensive 

hydrogeologic units

Mississippi River 

alluvial aquifer

Shallow sands

Eastern Florida 

Parishes Baton Rouge area

1 Aquifer unit

Southeastern Louisiana

1Aquifers in southern Mississippi and southeastern Louisiana are separated by unnamed discontinuous confining units. 

2Aquifer model layers are separated by confining model layers except model layers 9-18. Model layer 22 is the bottom model layer. 

Table 2. Aquifers and aquifer systems in southern Mississippi and southeastern Louisiana and corresponding mofrom Buono, 1975; Stuart and others, 1994; Lovelace and Lovelace, 1995; and Griffith, 2003). ,
Table 3. Time discretization summary. 

Stress 

Period Flow solution Years represented 

Flow time steps

 per stress period 

SEAWAT transport 

time steps 

Duration of first

flow time step 

1 Steady state 1900–39 1 1,790 Not applicable

2–69 Transient 1940–2007 5 14,763 33.4 days 

70–73 Transient 2008–2047 11 21,362 - 9,138 37.0 days 

1

Total number of transport time steps simulating 1940 through 2007. 

2

Number of transport time steps varied among scenarios 1 through 5. 
Table 4. Parameter values and sensitivities for the calibrated groundwater-flow model. 

[ft, foot or feet; numbers in parameter names correspond to aquifer name or layer number (see table 2); 

2k, “2,000-foot” sand. The fault hydraulic characteristic of the “2,000-foot” sand was specified for 6 fault 

segments: fault_2k, fault_2kmid, fault_2ka, fault_2kb, fault_2kc, and fault_2kw.] 

Parameter type Units Parameter name Calibrated value Composite sensitivity

Specified head ft bound_head 105.2 1.607 

Horizontal hydraulic 

conductivity ft/day 

 k_468sand 40.0 fixed 

 k_1200sand 34.0 1.009 

 k_1500sand1 See figure 12 various 

 k_1700sand 10.0 0.326 

 k_2000sand1 See figure 12 various 

 k_2400sand 14.5 0.611 

 k_2800sand 32.3 0.708 

 k_clay 1.E-05 fixed 

Vertical hydraulic 

conductivity ft/day 

 vk_sands 0.71 fixed 

 vk_2con 1.90E‐05 0.165

 vk_4con 8.59E‐05 0.126

 vk_6con 1.16E‐05 0.069

 vk_8con 1.45E‐03 0.206

 vk_19con 4.54E‐04 0.267

 vk_21con 2.28E‐05 0.231

Specific storage ft-1

 ss_sand 1.00E‐05 0.090

 ss_15 1.18E‐06 0.011

 ss_17 4.02E‐06 0.066

 ss_24 2.29E‐05 0.369

 ss_28 1.63E‐06 0.047

 ss_2ksand 3.10E‐06 0.055

 ss_clay2 1.29E‐06 0.005

 ss_clay4 1.65E‐06 0.009

 ss_clay6 1.00E‐06 0.023

 ss_clay8 2.98E‐06 0.061

 ss_clay19 1.00E‐06 0.028

 ss_clay21 1.00E‐06 0.020

Anisotropy of 

horizontal hydraulic 

conductivity 

dimensionless 

 hani15 3.00 0.289

 hani2k 1.15 0.980

Fault hydraulic 

characteristic day-1

 fault_lay_3 1.00E‐04 0.027

 fault_ lay_5 1.00E‐05 0.005

 fault_ lay_7 1.00E‐03 0.053

 fault_2k 1.00E‐03 0.017

 fault_2kmid 1.00E‐04 0.015

 fault_2ka 1.00E‐04 0.016

 fault_2kb 1.00E‐04 0.017

 fault_2kc 1.00E‐04 0.017

 fault_2kw 1.00E‐04 0.018

 fault_ lay_20 1.00E‐06 0.005

 fault_ lay_22 4.00E‐03 0.013

1

290 additional parameters represented horizontal hydraulic conductivity at pilot points in these aquifers. 
Table 5. Simulated steady-state and transient flow rates. 

[SP, stress period; TS, time step; ft3/d, cubic feet per day; Mgal/d, million gallons per day] 

Budget component Steady-state SP 1 (pre-1940) Transient SP 69, TS 5 (Dec. 31, 2007) 

ft3/d Mgal/d ft3/d Mgal/d 

In 

Specified-head layer 1 9.2742x106 69.38 1.5898x107 118.93 

South row of layer 22 0 0 6.5372x106 48.90 

Storage 0 0 2.3931x106 17.90 

Multi-node wells 0 0 2.4745x105 1.85 

Out 

Specified-head layer 1 8.3927x106 62.78 2.4214x106 18.11 

South row of layer 22 8.8141x105 6.60 0 0 

Storage 0 0 5.0110x104 0.37 

Multi-node wells 0 0 2.2605x107 169.10 
Table 6. Simulated plume areas and chloride concentrations. 

[mg/L, milligrams per liter; r, row; c, column] 

Date and scenario 

Plume area

(square miles)

Mean layer 18 cell

concentration (mg/L)

Median layer 18 cell 

concentration (mg/L) 

2007: (start for all scenarios) 5.10 955 411

2047: scenario 1 6.41 1,068 400

2047: scenario 3a: r57c26 5.08 1,230 655

2047: scenario 3b: r68c30 4.74 930 169

2047: scenario 4 6.39 1,047 393

2047: scenario 5 5.55 907 278