Prepared in cooperation with the Maine Geological Survey

Simulation of Groundwater Flow and Streamflow 

Depletion in the Branch Brook, Merriland River, and Parts of 

the Mousam River Watersheds in Southern Maine

Scientific Investigations Report 2014–5235

U.S. Department of the Interior

U.S. Geological Survey
Front cover photo. Branch Brook.
Simulation of Groundwater Flow and 

Streamflow Depletion in the Branch Brook, 

Merriland River, and Parts of the Mousam 

River Watersheds in Southern Maine

By Martha G. Nielsen and Daniel B. Locke

Prepared in cooperation with the Maine Geological Survey

Scientific Investigations Report 2014–5235

U.S. Department of the Interior

U.S. Geological Survey
U.S. Department of the Interior

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2015

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Suggested citation:

Nielsen, M.G., and Locke, D.B., 2015, Simulation of groundwater flow and streamflow depletion in the Branch Brook, 

Merriland River, and parts of the Mousam River watersheds in southern Maine: U.S. Geological Survey Scientific 

Investigations Report 2014–5235, 78 p., http://dx.doi.org/10.3133/sir20145235.

ISSN 2328-0328 (online)
iii

Acknowledgments

Staff of the Kennebunk, Kennebunkport and Wells Water District (KKWWD), and the Sanford 

Water District (SWD) were very generous in sharing numerous well logs and reports of previous 

aquifer investigations in the study area. John Roberts of the Maine Turnpike Authority shared 

drilling and engineering reports. J.H. Swett generously shared his experience and insight as 

local driller in the area for the last 40 years. The Nature Conservancy allowed access to wells 

at the Wells Blueberry Preserve for the water-level survey, and Matthew Reynolds of Drumlin 

Environmental provided field assistance in collecting water-level data during the water-level 

survey. Mark Holden of the Maine Department of Environmental Protection shared water-level 

measurements in monitoring wells in the Sanford area for the water-level survey. KKWWD and 

SWD staff also assisted in the water-level survey effort. Numerous residents of Sanford, Wells, 

and Kennebunk generously provided access to private wells for water-level measurements. 

Robert Gerber also was particularly generous in sharing reports, drilling records, and insight 

into the hydrogeology of the study area from previous modeling efforts. Luke Sturtevant, 

U.S. Geological Survey volunteer, was very helpful in the assembling and organizing well log 

data from the various agencies.

v

Contents

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

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

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

Description of the Study Area ............................................................................................................2

Previous Studies and Sources of Data .............................................................................................4

Groundwater and Surface-Water Resources...........................................................................................5

Geologic Setting....................................................................................................................................5

Surficial Geology and Mapped Soils ........................................................................................5

Bedrock .......................................................................................................................................10

Groundwater Resources ...................................................................................................................10

Hydraulic Properties .................................................................................................................10

Recharge.....................................................................................................................................12

Groundwater Levels ..................................................................................................................12

Long-Term Groundwater Levels .....................................................................................12

Synoptic Water-Level Survey .........................................................................................13

Groundwater Flow System................................................................................................................15

Surface-Water Resources ................................................................................................................16

Streamflow Measurements .....................................................................................................17

Calculation of State Requirements for In-stream Flows .....................................................17

Monthly Median Streamflows and In-stream Flow Requirements Based on 

Statewide Flow Equations .................................................................................17

Monthly Median Streamflows Based on Site-Specific Streamflow 

Measurements.....................................................................................................19

Comparison of Monthly Median Streamflows and Late Summer In-stream 

Flow Requirements Using the Two Methods..................................................19

Water Use and Withdrawals......................................................................................................................22

Sources of Water Use Data .....................................................................................................23

Reported Withdrawals.....................................................................................................23

Estimated Withdrawals....................................................................................................23

Reported and Estimated Withdrawals in the Study Area ...................................................23

Simulation of Groundwater Flow and Discharge to Streams...............................................................25

Conceptual Model of the Groundwater Flow System...................................................................25

Steady-State Numerical Groundwater Flow Model .....................................................................25

Spatial Discretization of the Model ........................................................................................25

Boundary Conditions.................................................................................................................28

Stresses.......................................................................................................................................28

Hydraulic Properties .................................................................................................................29

Model Calibration Using Parameter Estimation and Observations............................................29

Observations...............................................................................................................................31

Groundwater Level Observations ..................................................................................31

Streamflow Observations................................................................................................31

Parameters..................................................................................................................................32

Model Fit to Observations ........................................................................................................32
vi

Simulated Groundwater Levels and Flow Under Steady-State Conditions .....................36

Model Sensitivity Analysis and Parameter Uncertainty .....................................................36

Model-Calculated Water Budget for Branch Brook, the Merriland River, and 

Lower Mousam River............................................................................................................40

Scenario Testing .................................................................................................................................43

Use of the Groundwater Model to Determine Groundwater Divides and Flow Directions....43

Evaluation of Streamflow Depletion in Branch Brook and the Merriland River ...............................46

Simulation of Streamflow Depletion Using the Groundwater Flow Model ...............................46

Comparison of Streamflow Depletion Estimates to In-stream Flow Requirements .......47

Limitations of the Model ....................................................................................................................47

Summary and Conclusions.........................................................................................................................50

References Cited..........................................................................................................................................52

Appendix 1. Groundwater Observation Information...........................................................................57

Appendix 2. Dimensionless Scaled Sensitivities for Parameters ....................................................63

Figures

1. Map showing location of the study area, extent of the groundwater model area, 

and sand and gravel aquifers in the Branch Brook, Merriland River, and parts of 

the Mousam River watersheds in southern Maine.................................................................3

2. Map showing simplified surficial geology in the area in and around the 

Branch Brook watershed in southern Maine ..........................................................................7

3. Geologic cross sections A–A’, B–B’, and C–C’ for the area in and around the 

Branch Brook watershed in southern Maine ..........................................................................8

4. Maps showing generalized glacial geology at depths greater than 25 feet below the 

land surface in the area in and around the Branch Brook watershed in southern 

Maine: A, altitude of bedrock surface and thickness of surficial materials, and 

B, composition of glacial sediments at depth..........................................................................9

5. Graph showing long-term monthly water-level statistics for the U.S. Geological 

Survey groundwater monitoring well ME–YW 807 in Sanford, Maine ..............................13

6. Map showing locations of groundwater and streamflow measurement sites in 

the area in and around the Branch Brook watershed in southern Maine from 2010 

through 2012 ................................................................................................................................14

7. Graph showing streamflows measured on Branch Brook for selected dates 

between April 2010 and August 2011, southern Maine ........................................................18

8. Graph showing seasonal aquatic in-stream flow requirements calculated for 

Branch Brook and the Merriland River in southern Maine from statewide 

equations......................................................................................................................................20

9. Graphs showing comparison of annual hydrographs for A, Branch Brook and 

B, the Merriland River in southern Maine using two estimation methods, and the 

standard seasonal aquatic in-stream flow requirements calculated using 

statewide equations...................................................................................................................21

10. Map showing model grid and boundary conditions for the numerical groundwater 

flow model of the area in and around the Branch Brook watershed in southern 

Maine............................................................................................................................................26

11. Representation of model layers for cross-sections B–B’ and C–C’ in the area in 

and around the Branch Brook watershed in southern Maine............................................27
vii

12. Graph showing percentiles of daily streamflow in Branch Brook at station 

01069700 for June and July for the period of record, June and July daily streamflows 

for 2012, and the base-flow calibration target for the groundwater flow model, 

southern Maine...........................................................................................................................34

13. Map showing subwatersheds used as base-flow observation zones in the 

groundwater flow model of the area in and around the Branch Brook watershed in 

southern Maine...........................................................................................................................35

14. Graph showing relation between observed and model-simulated heads for the 

area in and around the Branch Brook watershed in southern Maine...............................37

15. Graph showing weighted residuals and unweighted simulated values for heads 

in the groundwater flow model of the area in and around the Branch Brook 

watershed in southern Maine ..................................................................................................38

16. Map showing spatial distribution of head residuals for the model domain in the 

area in and around the Branch Brook watershed in southern Maine...............................39

17. Graph showing steady-state observed and model-simulated base flow (groundwater discharge), with confidence intervals on the observed values, for the area 

in and around the Branch Brook watershed in southern Maine........................................40

18. Maps showing simulated steady-state groundwater heads and flow directions in 

A, layer 1 and B, layer 4 of the groundwater flow model of the area in and around 

Branch Brook watershed in southern Maine .......................................................................41

19. Graph showing final calibrated model parameter values, 95-percent confidence 

intervals, and reasonable ranges for hydraulic conductivity and recharge values 

for the groundwater flow model of the area in and around the Branch Brook 

watershed in southern Maine ..................................................................................................42

20. Graph showing steady-state simulated inflows and outflows for the Branch Brook, 

Merriland River, and Mousam River watershed areas in the groundwater flow 

model of the area in and around the Branch Brook watershed in southern Maine .......44

21. Maps showing groundwater divides and flow directions from simulated heads 

compared to topography-based watershed divides in the headwaters of the 

Branch Brook watershed in southern Maine: A, normal pumping and no pumping 

scenario and B, less recharge (drought) and increased pumping scenario....................45

22. Graph showing model-simulated base flow in Branch Brook from the headwaters 

to the end, showing the effects of pumping and drought, southern Maine......................48

23. Graph showing calculated monthly streamflows in Branch Brook and projections 

of streamflows accounting for direct withdrawals, streamflow depletion from 

pumping, and drought, southern Maine..................................................................................49

Tables

1. Water-supply wells in the Branch Brook, Merriland River, and parts of the 

Mousam River watersheds in southern Maine .......................................................................4

2. Hydraulic properties of hydrogeologic units in the area in and around the 

Branch Brook watershed in southern Maine ........................................................................11

3. Recharge rates to unconsolidated and shallow bedrock aquifer materials in 

southern Maine from previously published studies..............................................................12

4. Streamflow measurement site information, Mousam River, Branch Brook, and 

Merriland River watersheds in southern Maine from 2010 through 2012 .........................16

5. Watershed characteristics for the calculation of monthly median streamflows for 

Branch Brook and the Merriland River in southern Maine.................................................18
viii

6. Median monthly streamflows in Branch Brook and the Merriland River in southern 

Maine based on statewide equations.....................................................................................18

7. Median monthly flows in Branch Brook and the Merriland River in southern Maine 

based on site-specific streamflow data and regressions with local index sites.............20

8. Comparison of monthly median streamflows for Branch Brook and the Merriland 

River in southern Maine ............................................................................................................22

9. Estimated withdrawals from groundwater and surface water, 2010, for the area 

in and around the Branch Brook watershed in southern Maine by water use 

category .......................................................................................................................................24

10. Pumping wells simulated in the groundwater flow model of the area in and around 

the Branch Brook watershed in southern Maine..................................................................30

11. Hydrogeologic units and corresponding hydraulic properties...........................................30

12. Riverbed and streambed hydraulic properties......................................................................31

13. Summary of groundwater level observation points used in calibrating the 

groundwater flow model of the area in and around the Branch Brook watershed 

in southern Maine.......................................................................................................................31

14. Streamflow observations used in calibrating the Branch Brook area groundwater 

flow model....................................................................................................................................33

15. Parameters used in the groundwater flow model of the area in and around the 

Branch Brook watershed in southern Maine, with composite scaled sensitivities 

and calibrated values.................................................................................................................36

16. Steady-state model calculated water budget fluxes for the Branch Brook area 

groundwater flow model and three primary watersheds within the model area............43

17. Model-calculated streamflow depletion in Branch Brook and the Merriland River ......47
ix

Conversion Factors, Datum, and Abbreviations

Inch/Pound to SI

Multiply By To obtain

Length

inch (in) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 2.590 square kilometer (km2)

Volume

gallon (gal) 3.785 liter (L)

million gallons (Mgal) 3,785 cubic meter (m3)

Flow rate

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

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)

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

inch per year (in/yr) 25.4 millimeter per year (mm/yr)

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 North American Vertical Datum of 1988 

(NAVD 88).

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

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

*Transmissivity: The standard unit for transmissivity is cubic foot per day per square foot times 

foot of aquifer thickness [(ft3/d)/ft2]ft. In this report, the mathematically reduced form, foot 

squared per day (ft2/d), is used for convenience.
x

Abbreviations

GHB general head boundary

GIS geographic information system

GPS global positioning system

MODFLOW modular three-dimensional finite-difference groundwater model

MOVE.1 maintenance of variance, type 1

MGS Maine Geological Survey

USGS U.S. Geological Survey
Simulation of Groundwater Flow and Streamflow 

Depletion in the Branch Brook, Merriland River, and 

Parts of the Mousam River Watersheds in Southern Maine

By Martha G. Nielsen and Daniel B. Locke

Abstract

Watersheds of three streams, the Mousam River, Branch 

Brook, and Merriland River in southeastern Maine were 

investigated from 2010 through 2013 under a cooperative 

project between the U.S. Geological Survey and the Maine 

Geological Survey. The Branch Brook watershed previously 

had been deemed “at risk” by the Maine Geological Survey 

because of the proportionally large water withdrawals compared to estimates of the in-stream flow requirements for 

habitat protection. The primary groundwater withdrawals in 

the study area include a water-supply well in the headwaters 

of the system and three water-supply wells in the coastal 

plain near the downstream end of the system. A steady-state 

groundwater flow model was used to understand the movement of water within the system, to evaluate the water budget 

and the effect of groundwater withdrawals on streamflows, 

and to understand streamflow depletion in relation to the 

State of Maine’s requirements to maintain in-stream flows for 

habitat protection.

Delineation of the simulated groundwater divides 

compared to the surface-water divides suggests that the 

groundwater divides in the headwater areas do not exactly 

correspond to the surface-water divides. Under both pumping 

and non-pumping conditions, groundwater flows from the 

headwaters of the Branch Brook watershed into the Mousam 

River watershed. Pumping in the Mousam River watershed 

captures a small amount of groundwater from the Branch 

Brook basin. 

The cumulative effect of groundwater withdrawals on 

base flows in two rivers in the study area (Branch Brook and 

the Merriland River) was evaluated using the groundwater 

flow model. Streamflow depletion in the headwaters of 

Branch Brook was 0.12 cubic feet per second (ft3/s) for the 

steady-state simulation, or about 10 percent of the average 

base flow at that location. Downstream on Branch Brook, the 

total streamflow depletion from all the wells was 0.59 ft3/s, 

or 3 percent of the average base flow at that location. In the 

Merriland River downstream from the Merriland River well, 

the total amount of streamflow depletion was 0.6 ft3/s, or about 

7 percent of the average base flow.

The groundwater model was used to evaluate several different scenarios that could affect streamflow and groundwater 

discharging to the rivers and streams in the study area. The 

scenarios were (1) no pumping from the water-supply wells; 

(2) current pumping from the water-supply wells, but simulated drought conditions (25 percent reduction in recharge); 

(3) current recharge, but with increased pumping from the 

large water-supply wells; and (4) drought conditions and 

increased pumping combined. 

Simulations of increased pumping in the water-supply 

wells resulted in streamflow depletion in the headwaters 

of Branch Brook increasing to 16 percent of the headwater 

base flow. Simulated increases in the pumping in the coastal 

plain wells increased the amount of streamflow depletion 

to 6 percent of the flow in Branch Brook and to 8 percent 

of the flow in the Merriland River. The additional stress of 

a drought imposed on the model (25 percent less recharge) 

had a substantial impact on streamflows, as expected. If the 

simulated drought occurred simultaneously with an increase 

in pumping, the base flows would be reduced 48 percent in 

the headwaters of Branch Brook, compared to the no-pumping 

scenario. Downstream in Branch Brook, the total reduction 

in flow would be 29 percent of the simulated base flows 

in the no-pumping scenario, and in the Merriland River, 

the reduction would be 33 percent of the base flows in the 

no-pumping scenario.

The study evaluated two different methods of 

calculating in-stream flow requirements for Branch Brook 

and the Merriland River—a set of statewide equations 

used to calculate monthly median flows and the MOVE.1 

record-extension technique used on site-specific streamflow 

measurements. The August median in-stream flow requirement 

in the Merriland River was calculated as 7.18 ft3/s using the 

statewide equations but was 3.07 ft3/s using the MOVE.1 

analysis. In Branch Brook, the August median in-stream flow 

requirements were calculated as 20.3 ft3/s using the statewide 

equations and 11.8 ft3/s using the MOVE.1 analysis. In each 

case, using site-specific data yields an estimate of in-stream 

flow that is much lower than an estimate the statewide 

equations provide.
2 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

Introduction

In 2009, the U.S. Geological Survey (USGS) and the 

Maine Geological Survey (MGS) began a cooperative project 

to provide a rigorous evaluation of the hydrologic effects of 

withdrawals in “watersheds at risk” in the State of Maine 

(Nielsen and Locke, 2011). The results of the initial study 

under this cooperative project, in Freeport, Maine, indicated 

the importance of high-quality site-specific data in analyzing the hydrologic effects of withdrawals. That study of a 

small watershed (less than 10 square miles [mi2]) having only 

one withdrawal well served as a pilot for the overall project. 

The Freeport aquifer study concluded that using site-specific 

streamflow data provided estimates of the monthly median 

streamflows that were significantly different from the standard 

estimation method for determining seasonal in-stream flows, 

which uses statewide equations for the monthly median flows, 

particularly in a very small watershed (Nielsen and Locke, 

2011). The use of a numerical groundwater flow model in that 

study indicated how streamflow depletion from withdrawal 

wells could be quantified and used to estimate summertime 

pumping effects on streamflow under drought conditions, 

potential future increased withdrawals, or both. The construction and calibration of the Freeport aquifer groundwater flow 

model revealed groundwater flow directions and connections 

between deep and shallow aquifers that were not otherwise 

apparent (Nielsen and Locke, 2011).

As a second study under the USGS-MGS cooperative 

project, a study of watersheds in the towns of Kennebunk, 

Wells, and Sanford, Maine, was begun in 2010, using 

similar methods to the Freeport aquifer study but on a larger 

study area with more complex geology and groundwater 

withdrawals. The study uses an evaluation of the water budget 

and simulations of streamflow depletion, determined through 

use of a numerical groundwater flow model, to evaluate the 

effect that groundwater withdrawals have on streamflows 

and groundwater within the system. This study, like the 

earlier Freeport aquifer study (Nielsen and Locke, 2011), 

is intended to provide insight into the effect of withdrawals 

on streamflows under a certain set of conditions (that is, the 

withdrawal conditions and aquifer geometry presented by 

the specific study area) and is intended to help understand 

streamflow depletion in light of the State requirements to 

maintain in-stream flows for habitat protection.

The MGS identified two adjacent watersheds in 

the Kennebunk, Maine, area (fig. 1) as having permitted 

groundwater and surface-water withdrawals in combination 

with flows required to meet in-stream flow requirements that 

are quite large in comparison to the total annual runoff (Robert 

G. Marvinney, Maine Geological Survey, written commun., 

2011). These watersheds (the Branch Brook and Merriland 

River watersheds) and the glacial aquifer from which water 

is withdrawn are the focus of the study area. Adjacent parts 

of the Mousam River watershed are included in the study 

area because of uncertainty in the position of the groundwater 

divide and groundwater flow directions between the Branch 

Brook and Merriland River watersheds and the Mousam 

River watershed. 

The use of a numerical groundwater flow model, 

which allows water to be accounted for as it flows through 

the groundwater system to the surface-water system, was 

intended to address several areas of concern in the study area. 

These include (1) to evaluate the effect of water management 

practices on streamflow and quantify streamflow depletion in 

Branch Brook and the Merriland River, (2) to help refine the 

conceptual model of groundwater flow in the study area, as 

the possible source of groundwater to some of the withdrawal 

wells was poorly understood at the outset, and (3) to delineate 

the groundwater divide between the Mousam River, Branch 

Brook, and the Merriland River watersheds. The study had 

two additional goals in support of a better understanding of 

water resource management in the watersheds, which were 

to fully account for all water withdrawals, not just permitted 

withdrawals, and to evaluate two different methods of calculating in-stream flow requirements for Branch Brook and the 

Merriland River.

This report describes the determination of total water 

use in the study area, the use and calibration of a steady-state 

groundwater flow model of the Branch Brook, Merriland 

River, and part of the Mousam River watersheds, and its use in 

evaluating the effect of groundwater withdrawals on streamflow in those watersheds. The data collected to construct and 

calibrate the groundwater flow model are presented. Simulation results for varying water withdrawal and climatic scenarios on the water budgets for Branch Brook, the Merriland 

River, and part of the Mousam River watershed are described. 

The parameter estimation used for model calibration, model 

sensitivities and limitations, and prediction uncertainties also 

are reported for the model. The report presents a summary 

of the effect of withdrawals on streamflows in the study area 

and on the overall movement of water through the hydrologic 

system. In addition, an analysis of two methods for the calculation of state in-stream flow requirements for Branch Brook 

and the Merriland River are presented.

Description of the Study Area

The study area includes the Branch Brook and Merriland 

River watersheds and part of the Mousam River watershed 

south of the Mousam River and east of Sanford (total area 

51.8 mi2) in southern coastal Maine (fig. 1). This includes 

parts of the towns of Kennebunk, Wells, and Sanford. The 

groundwater model covers the entire study area. Although the 

primary focus of the study is Branch Brook and the Merriland 

River, the adjacent parts of the Mousam River watershed were 

included in the study and the groundwater model because of 

uncertainties in the hydrologic boundaries along the Branch 

Brook-Mousam River divide and the Merriland RiverMousam River divide. The study area forms a northwestsoutheast trending oblong-shaped area that has its headwaters 

in the eastern part of the city of Sanford and ends in a narrow 
Introduction 3

£¤1

ME-YW807 § ̈¦95

01069700

01069500

01068910

Wells

Sanford Kennebunk

Alfred Lyman

1

4

3

5

2

6

8

7

Water bodies, watersheds, towns, and roads from U.S. Geological Survey digital line graphs 1:24:000, 2010.

Shaded relief from U.S. Geological Survey National Elevation Dataset, 1/3- and 1/9-arc second data, 2013.

North American Datum of 1988

Universal Transverse Mercator projection

State plane Maine West FIPS 1802 coordinate system

01069700

EXPLANATION

Town boundaries

Watershed boundaries

Long-term groundwater observation well

Streamgage with identification number

6 to 20

21 to 500

501 to 1000

Production well, pumping rate in gallons 

per minute (numbers refer to table 1) Groundwater model

Model boundary

Active model boundary

Sand and gravel aquifers, by yield

10 to 50 gallons per minute

More than 50 gallons per minute

7

5

8

ME-YW807

MAINE

0 25 50 100 KILOMETERS

50250 100 MILES Study area

Portland

Sand and gravel aquifers from Neil and Smith (1998a-d). 

0 10.5 2 3 4 KILOMETERS

0 0.5 1 2 3 4 MILES

Merriland River

Atlantic 

Ocean

Little River

Mou sam

River

Mousam River

Mousam

River

Branch Brook

Cold Water Bk.

Perkins Marsh B k.

Day Brook

Figure 1. Location of the study area, extent of the groundwater model area, and sand and gravel aquifers in the Branch Brook, 

Merriland River, and parts of the Mousam River watersheds in southern Maine.
4 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

strip along the ocean 10 miles (mi) farther to the east. All of 

the primary surface-water features (the Mousam River, Branch 

Brook, and Merriland River) flow from west to east towards 

the ocean. The study area (and groundwater model) is 6 miles 

across in the north-south direction and 13 miles long in the 

east-west direction.

Within about 2–3 miles of the coastline, the study area 

consists of a generally flat coastal plain. A series of northeastsouthwest trending ridges (of about 125 to 150 feet high) 

separates the coastal plain area from the inland areas. Inland of 

these ridges, the Branch Brook/Mousam River watershed areas 

are characterized by a sandy, gently sloping plateau (sloping 

northeast towards the Mousam River) which is dissected by 

streams (primarily Branch Brook and its tributaries). South of 

the Branch Brook watershed, the Merriland River watershed 

is underlain primarily by till and thin-soil-covered bedrock 

uplands. Farther to the west, the sandy plateau broadens to 

include all three watersheds. Furthest to the west, the study 

area ends in the hills to the south of Sanford, and in uplands 

across the West Branch of the Mousam River. The Mousam 

River forms the northernmost boundary of the study area. 

Total topographic relief is 370 feet.

The Merriland River watershed composes 16.4 mi2, or 

31.7 percent of the study area. The Branch Brook watershed 

(13.7 mi2, or 26.4 percent of the study area), the Mousam 

River watershed (20.3 mi2, 39.2 percent), and a small coastal 

section (1.4 mi2, 2.7 percent of the total study area) compose 

the remainder of the study area. The Merriland River watershed is underlain by till and bedrock in its lower reaches 

and converts precipitation into runoff more quickly than the 

Branch Brook watershed, which has abundant sandy soil and 

greater opportunity for groundwater recharge and has more 

consistent groundwater discharge during dry periods.

Most of the study area has been mapped as a significant 

sand and gravel aquifer by the MGS (fig. 1; Neil and Smith, 

1998a–d). The Branch Brook watershed and Mousam River 

watershed area are almost entirely designated as significant 

sand and gravel aquifers, as are the headwater areas of the 

Merriland River watershed.

The mean annual precipitation in the study area from 

1961 through 1990 is 45.9 inches (Oregon State University, 

2010; Natural Resources Conservation Service, 1998). The 

closest long-term temperature station is in Portland, Maine, 

23 mi northeast of the center of the study area. The average 

annual temperature for the Portland station is 45.7 degrees 

Fahrenheit (°F) (National Weather Service, 2010), which is 

expected to be the same in the Kennebunk/Wells/Sanford area 

because of similar elevation, distance from the Atlantic Ocean, 

and proximity to each other.

Land use in and around the study area is primarily rural 

residential with the exceptions of the commercial-industrial 

area of South Sanford and the Sanford airport, residential 

areas of the town of Kennebunk, and the U.S. Route 1 corridor, which has a substantial amount of commercial development. The rural residential areas are largely forested with 

interspersed areas of hayfields along roadways and areas of 

unbroken forest between adjacent road and residential corridors. Several large areas of blueberry barrens and other open 

space cover the flat sandy plateau in the center of the study 

area near Branch Brook. The population density in most of 

the study area is less than 200 persons per square mile. Small 

rural subdivisions (in the range of 10 to 50 houses) can have 

population densities of 1,000 persons per square mile or more, 

and residential neighborhoods in the towns of Kennebunk and 

Sanford have population densities of 1,000 to 3,000 persons 

per square mile (U.S. Census Bureau, 2010). Total population 

in the study area is 11,962 (U.S. Census Bureau, 2010).

There are four large water-supply withdrawal wells 

(pumping between 150 and 1,000 gallons per minute) in the 

study area and four small water-supply wells (pumping less 

than 20 gallons per minute) (fig. 1, table 1). The four large 

withdrawal wells include a well in the western part of the 

study area in the town of Sanford, a well in the coastal plain 

near the Merriland River, and two wells near Branch Brook, 

also in the coastal plain area. The four small withdrawal wells 

are scattered across the central part of the study area. The large 

water-supply wells, plus a direct surface-water withdrawal 

from Branch Brook, together make up a relatively large total 

use of water in this study area compared to its size, according 

to analyses by the MGS (Robert G. Marvinney, written commun., 2011).

Previous Studies and Sources of Data

Information on the geology and hydrogeology of the 

Branch Brook-Merriland River study area is available from 

many sources. The State of Maine has published a series of 

bedrock geologic maps, surficial geologic maps and reports, 

and significant sand and gravel aquifer maps that cover 

the study area (Hussey and others, 2008; Neil and Smith, 

1998a–d; Tolman and others, 1983; Smith, 1999a–f). The 

Table 1. Water-supply wells in the Branch Brook, Merriland 

River, and parts of the Mousam River watersheds in southern 

Maine. 

[Large wells in the study area pumping between 150 and 1,000 gallons per 

minute. Small wells pump less than 20 gallons per minute.]

Map 

number 

(figure 1)

Well name Well type

1 Sanford well Large water-supply well

2 Mobile home park “A” well Small water-supply well

3 Mobile home park “B” well Small water-supply well

4 Mobile home park “C” well Small water-supply well

5 Mobile home park “D” well Small water-supply well

6 Plant well Large water-supply well

7 Harriseckett well Large water-supply well

8 Merriland River well Large water-supply well
Groundwater and Surface-Water Resources 5

hydrologic framework and surficial geology in the central 

part of the study area, known as the Sanford outwash plain, 

has been reported on by several investigators (Bloom, 1959; 

D’Amore, 1983; Hanson, 1984; Tary, 1999; Tary and others, 

2001; and Schnitker and others, 2001). Interpretations of the 

hydrogeology of this area have been discussed by Bloom 

(1959), Robert G. Gerber, Inc. (1981), D’Amore (1983), and 

Hanson (1984). Well logs and other hydrologic data for the 

York County and southern Cumberland County area were 

published in Prescott and Drake (1962) and Tolman and 

others (1983). Long-term continuous groundwater level data 

are available from USGS well ME YW-807 (http://me.water.

usgs.gov; fig. 1), and continuous-record streamflow data 

for USGS streamgages are available for stations 01069500, 

01069700, and 01068910 (http://me.water.usgs.gov; fig. 1). 

Both of the large water utilities in the study area, the Sanford 

Water District (SWD) and Kennebunk, Kennebunkport, 

and Wells Water District (KKWWD), have collected data 

and conducted small-scale hydrogeological investigations 

in the study area. These have been a source of most of the 

well logs used in this study as well as a source of additional 

hydrogeologic information (Camp, Dresser, and McKee, 1965; 

Robert G. Gerber, Inc., 1981; Whitman and Howard, Inc., 

1981; Whitman and Howard, Inc., 1984; Caswell, Eichler, 

and Hill, Inc., 1989; Robert G. Gerber, Inc., 1993; Caswell, 

Eichler, and Hill, Inc., 1995a; Caswell, Eichler, and Hill, 

Inc., 1995b; Caswell, Eichler, and Hill, Inc., 1995c; CEHJacques Whitford, 1997; GS Environmental and Groundwater 

Associates, Inc., 2002).

Additional sources of data include boring logs from the 

Maine Turnpike Authority (Maine Turnpike Authority, written 

commun., 2012), well drillers’ reports from the MGS, and surficial seismic lines collected by the MGS for this study (Maine 

Geological Survey, written commun., 2012).

Groundwater and Surface-Water 

Resources

The hydrologic system in the study area can be described 

by the groundwater and surface-water resources that exist 

within the geologic setting. The geologic materials in the study 

area are generally saturated with water throughout, except for 

a shallow unsaturated zone in either the surficial materials or 

shallow fractured bedrock exposed on hilltops. Rainfall penetrating the surficial materials becomes groundwater, which 

flows through the surficial glacial materials and shallow bedrock to discharge zones in the streams, rivers, and ocean. Flow 

paths through the unconsolidated materials are generally short, 

as the distance to the nearest river or stream discharge point is 

short (less than 5 miles) for any given location in the glacial 

aquifer in the study area. Flow paths for groundwater that 

penetrates deep into the bedrock can be much longer, although 

shallow bedrock flow paths also may be quite short (less than 

a few miles) (Gerber, 1988).

Geologic Setting

The geologic units in the study area include fractured 

crystalline bedrock and stratified, unconsolidated glacial and 

post-glacial deposits that are draped over the bedrock. The glacial deposits include till (in moraines and as a blanket deposit), 

stratified marine sand and gravel, marine silt and clay, beach 

and nearshore sand and gravel deposits, and sandy deltaic 

deposits. (Smith, 1999e, d, f). More recent sediments include 

Holocene stream alluvium and Holocene wetlands.

Surficial Geology and Mapped Soils

As numerous authors have written about the glacial and 

post-glacial history and surficial geology of the coast of Maine 

south of Portland, this report will not attempt to provide a 

thorough summary of these studies. Readers are referred to 

Bloom (1959), Upson and Spencer (1964), D’Amore (1983), 

Hanson (1984), Smith (1999e,d,f), Tary (1999), Schnitker and 

others (2001), and Tary and others (2001) for further details of 

the surficial geology and geologic history of the study area.

In brief, after the last glacial maximum, the melting 

glacier retreated northward past coastal Maine, leaving 

numerous deposits as the retreat occurred. The retreat was 

accompanied by a marine transgression onto the depressed 

land surface so that sediments carried by the melting glacier 

were deposited in a shallow marine environment (Weddle 

and Retelle, 1995; Neil, 1997; Smith 1999d). Deposited 

underneath the glacier, dense unsorted sediment (till) is the 

stratigraphically lowermost unit in the study area, overlying 

the bedrock surface. As the glacier retreated, meltwater carried 

coarse-grained sediment in channels under the glacier, which 

settled out as coarse-grained deltaic deposits near the toe of 

the retreating glacier, most likely in the marine environment 

(Bloom, 1959; D’Amore, 1983; Weddle and Retelle, 1995; 

Tary, 1999; Tary and others, 2001), although some ascribe 

these deltaic deposits to a subaerial deposition framework 

(Smith, 1999d). These submarine deltaic deposits form most 

of the sand and gravel aquifers within the study area. Smaller 

areas of ice-contact deposits (sand and gravel) also are found 

in a few places in the northwestern one-half of the study 

area and compose some of the most high-yielding aquifer 

zones. Farther out to sea from the zone of delta deposition, 

finer sediments were being deposited across the submarine 

landscape, with deposits being thicker in the deepest troughs 

and thinner to non-existent in the shallower areas because of 

the distribution of ocean currents and wave action (D’Amore, 

1983). This deposit formed a widespread silt and clay layer 

known as the Presumpscot Formation (Bloom, 1960; 1963).

As the glacier retreated farther inland, the land surface 

rebounded, exposing the marine sediments first to wave 

action and then to subaerial erosion and deposition. During 

this phase, the top layer of marine sediments was reworked 

by wave action, leaving widespread nearshore sandy deposits over some areas of the silt and clay (Weddle and Retelle, 

1995; Smith, 1999d). Wind and water further reworked these 
6 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

sediments, creating dune features, exposing till uplands, and 

filling in stream valleys with alluvial deposits.

A simplified map of the surficial geology of the study 

area is shown in figure 2. Cross sections showing the interpreted glacial geology at depth in three parts of the study area 

are shown in figure 3 (see fig. 2 for cross-section locations). 

A combination of surficial geology mapped by the Maine 

Geological Survey in the Wells, Kennebunk, Alfred, and 

North Berwick 1:24,000 quadrangles (Neil, 1999; 1999a–e) 

and interpretation from recently acquired (2010) lidar data are 

shown in figure 2. The lidar data primarily were used to adjust 

the boundaries between the geologic units in areas covered 

by thick forest cover, as the earlier mapping had much less 

detailed topographic information to use in drawing the boundaries between units. 

Till is the stratigraphically lowest glacial unit in the 

study area and directly overlies the bedrock. The till can range 

from 0 to more than 20 feet thick in well logs, but it is widely 

distributed across the study area. There are many areas where 

the glacial deposits are quite thin, and these have been mapped 

as thin glacial deposits over bedrock (fig. 2). A thin, dense till 

unit (less than 5 ft thick) is found to directly overlie the bedrock in most drilling records that go all the way to the bedrock 

surface and is shown as an inferred unit on top of the bedrock 

in figure 3.

The ice-contact and marine deltaic deposits (described by 

Smith [1999d, e] as ice-frontal marginal deltas or ice-contact 

deltas) occur primarily in the western one-third of the study 

area (figs. 2 and 3, cross section A–A′). These are the most 

coarse-grained deposits described in the study area and are 

composed of coarse sand and gravel grading to sand. The distal delta deposits (called outwash deltas by Smith [1999d, e]) 

are more fine grained and overlie a large part of the study area. 

They are composed of stratified sand, gravel, and silt. They 

overlie the silt and clay of the Presumpscot Formation in most 

locations (example shown in fig. 3, cross section B–B′). In 

areas of poor access or exposure (or both), the marine deposits 

are mapped as “undifferentiated” and may be sandy or silt-clay 

deposits, or sandy deposits over silt and clay or till.

The stratigraphically uppermost glacial units are nearshore marine deposits, generally deposited above the silt and 

clay of the Presumpscot Formation in the coastal plain area 

(fig. 3, cross section C–C′). Sandy deposits overlying the silt 

and clay of the Presumpscot Formation have often been identified as an upper nearshore sand facies of the formation but 

have sometimes been determined to unconformably overlie the 

silt and clay (Weddle and Retelle, 1995). Post-glacial alluvium 

can be found in many of the stream valleys in the study area. 

Wetlands cover many areas that are flat and poorly drained, 

either because of underlying fine-grained material (Presumpscot Formation) or the presence of a high water table, or both.

The glacier scoured a surface that ranges from the bedrock highs (340 ft) to buried troughs as much as and exceeding 

150 ft below sea level (Upson and Spencer, 1964, D’Amore, 

1983, Tary, 1999), which were filled in with glacial sediments 

during the glacial and post-glacial history described above. 

The surficial geologic maps do not provide information on the 

distribution of the geologic units at depth, and the surficial 

geologic reports provide only a conceptual glacial stratigraphic 

framework. For this study, more than 150 well logs (fig. 4) 

contained in numerous consulting reports were examined 

to help determine the thickness and grain size of the glacial 

materials below the surface, and more than 500 data points 

were used (including well and boring logs, outcrops, seismic 

lines, and drillers reports) to determine the elevation of the 

bedrock surface. MGS collected an additional 10 seismic lines 

for this study to help determine the depth to bedrock in the 

coastal plain area (Camp, Dresser, and McKee, Inc., 1965; 

Whitman and Howard, Inc., 1981; Whitman and Howard, Inc., 

1984; Caswell, Eichler, and Hill, Inc., 1989; Caswell, Eichler, 

and Hill, Inc., 1995a; Caswell, Eichler, and Hill, Inc., 1995b; 

Caswell, Eichler, and Hill, Inc., 1995c; CEH-Jacques Whitford, 1997; GS Environmental and Groundwater Associates, 

Inc., 2002; Scott J., Minor, KKWWD, written commun., 2012; 

Maine Turnpike Authority, written commun., 2012; Maine 

Geological Survey, written commun., 2012; Henry Sweatt, 

private driller, oral commun., 2012). The cross sections (fig. 3) 

were developed using all of these data. The total thickness of 

the materials above the bedrock surface and the texture of the 

materials at depths greater than about 25 feet below the land 

surface are shown in figure 4.

In the central part of the study area, the geologic materials below the surficial deltaic deposits are silt and clay 

(Presumpscot Formation; fig. 4). There is a very deep (more 

than 150 foot [ft]) trough in this area, and the well log for the 

only boring that penetrated this depth indicated silt and clay 

all the way to the basal till just above the bedrock (Tolman 

and others, 1983). In the western one-third of the study area, 

the total thickness of the surficial materials ranges from 25 

to greater than 100 ft (figs. 3 and 4). These surficial materials 

include a stratified mix of silt (and some clay) and sand that 

grade westward into coarser materials (predominantly sand 

and gravel) located in the area of the ice-contact and deltaic 

deposits deposited closest to the edge of the glacier. Little silt 

and clay is found at depth in the northwestern and northern 

part of the study area. In the southeastern part of the study 

area, a deep trough trends generally north-south; the surficial materials are generally from 50 to 100 ft thick, and are 

more than 150 ft thick in some places (figs. 3 and 4). Close 

to the Atlantic Ocean, the materials at depth are described in 

the well logs to be dominated by silt and clay (Presumpscot 

Formation); farther inland there is a more heterogeneous mix 

of silt and clay and sand with little silt and clay in some areas 

(fig. 4). On the basis of well logs for production and monitoring wells between Branch Brook and the Merriland River 

(Scott J. Minor, written commun., 2012), there is a deep buried 

gravel aquifer below the Presumpscot Formation silt and clay 

not described in any of the previous studies (fig. 4). The sediments described in these well logs include some very coarse 

gravel deposits interbedded with sand. Figure 3 shows an 

outline of the possible extent of this buried gravel aquifer. Few 

well logs in this area penetrated as deep as the bedrock, so this 

buried aquifer could extend farther north or south than shown.
Groundwater and Surface-Water Resources 7

Wells

Sanford Kennebunk

Alfred

A

A'

B

B'

C'

C

Wetlands

Alluvium

Nearshore marine deposits (sandy)

Ice-frontal marine delta deposits

Distal delta deposits

Undifferentiated marine deposits

Presumpscot Formation

Till

Thin glacial deposits over bedrock

Water bodies

Surficial geology

Town boundary

Watershed boundary

Cross section location

Groundwater model

Model boundary

Active model boundary

EXPLANATION

Water bodies, watersheds, towns, and roads from U.S. Geological Survey digital line graphs 1:24:000, 2010.

Shaded relief from U.S. Geological Survey National Elevation Dataset, 1/3- and 1/9-arc second data, 2013.

North American Datum of 1988

Universal Transverse Mercator projection

State plane Maine West FIPS 1802 coordinate system

Surficial geology modified from Smith (1993, 1999c,d) and Neil (1999)

0 10.5 2 3 4 KILOMETERS

0 0.5 1 2 3 4 MILES

Merriland River

Atlantic 

Ocean

Little River

Mo u sam River

Mousam River

Branch Brook

Cold Water Bk.

Perkins Marsh Bk.

Day Brook

Figure 2. Simplified surficial geology in the area in and around the Branch Brook watershed in southern Maine.
8 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

Layered sand and coarse gravel

Presumpscot Formation

Nearshore marine deposits

Bedrock (metamorphic)

Land surface

Till

? ?

Alluvium

Alluvium

15,000 14,000 13,000 12,000 11,000 10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000

604020

NAVD 88

-20-40-60-80

-100-120

Elevation, in feet

Distance, in feet

C' C

Merriland River Branch Brook Mousam River

VERTICAL SCALE GREATLY EXAGGERATED

200180160140120100

80604020

Elevation, in feet

28,000 26,000 24,000 22,000 20,000 18,000 16,000 14,000 12,000 10,000 8,000 6,000 4,000 2,000

Bedrock (Webhannet pluton)

Till

Distal delta deposits

Land surface

Presumpscot Formation

Undifferentiated marine deposits

Till

B' B Merriland River

Branch Brook Mousam River

DATUM IS NAVD 88. VERTICAL SCALE GREATLY EXAGGERATED

320300280260240220200180160140120

18,000 16,000 14,000 12,000 10,000 8,000 6,000 4,000 2,000

Elevation, in feet Distal delta deposits

A A'

Land surface

Till Bedrock (Lyman pluton) Ice-contact deposits

BEND IN

SECTION

Water

Mousam River Mousam River Estes Lake

DATUM IS NAVD 88. VERTICAL SCALE GREATLY EXAGGERATED

BEND IN

SECTION

Figure 3. Geologic cross sections 

A

–

A’, B–

B’, and 

C–

C’ for the area in and around the Branch Brook watershed in southern Maine.
Groundwater and Surface-Water Resources 9

Model boundary

Active model 

boundary

Groundwater model

Thin till over bedrock 

and sand and gravel 

less than 25 feet thick

Water body

Buried gravel aquifer

—Location inferred

Glacial sediments at depth

Silt and clay

Silt and clay and sand

Primarily sand

Sand and gravel

EXPLANATION

0 1 2 3 4 0.5 MILES

0 1 2 4 KILOMETERS

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Buried gravel 

aquifer—Location inferred

Cross section 

Thickness of surficial 

materials—Contour 

interval 25 ft

100

! Surficial materials and 

well logs

Model boundary

Active model boundary

Groundwater model

Low : -146.8

High : 341.5

Elevation of bedrock surface, 

in feet relative to NAVD 88

Water body

EXPLANATION

Water bodies from U.S. Geological Survey digital line graphs, 1:24,000, 2010. Universal Transverse Mercator projection, zone 19

State plane Maine West FIPS 1802 coordinate system

North American Datum of 1988

A.

B.

B'

C

C'

A'

B

A

0 1 2 3 4 0.5 MILES

0 1 2 4 KILOMETERS

Merriland River

Little River

Mo usam River

Mousam River

Branch Brook

Merriland River

Atlantic 

Ocean

Little River

Mo usam River

Mousam River

Branch Brook

Atlantic 

Ocean

P

Cold Water Bk.

erkins Marsh Bk.

Day Brook

Figure 4. Generalized glacial geology at depths greater than 25 feet below the land surface in the area in and around 

the Branch Brook watershed in southern Maine: A, altitude of bedrock surface and thickness of surficial materials, and 

B, composition of glacial sediments at depth. Datum is North American Vertical Datum of 1988 (NAVD 88).
10 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

Bedrock

Bedrock in the study area consists of several Silurianand Siluro-Ordovician-aged metamorphic rock units intruded 

by igneous rocks of Permian, Devonian, and Carboniferous 

age (Hussy and others, 2008). The metamorphic rock units 

trend northeast-southwest parallel to the coastline. The 

Silurian Berwick Formation is thrust over the older SiluroOrdovician rocks of the Merrimack Group along the Nonesuch 

River fault (Hussey and others, 2008), which crosses the 

study area along a line roughly parallel to the Sanford town 

line (fig. 1). The location of this fault is inferred, as the rocks 

are deeply buried in this location. The western one-third of 

the study area is underlain by the Permian age Lyman pluton, 

which is a granite-pegmatite unit (fig. 3, cross section A–A′). 

The Devonian Webhannet pluton (granite) underlies much 

of the eastern one-half of the Merriland River watershed and 

the central part of the Branch Brook watershed (Hussey and 

others, 2008; see fig. 3, cross section B–B′).

Groundwater Resources

Groundwater resources in the study area occur in the 

bedrock units and in the unconsolidated surficial deposits, but 

the surficial deposits provide the great majority of the available groundwater resource for human use. Groundwater occurs 

in the bedrock units in fractures, faults, and joints, and the 

bedrock is generally capable of supplying only a few gallons 

per minute of water to wells, so it is not considered a major 

groundwater resource.

Groundwater resources in the study area have been 

explored since the 1960s when local water utilities searched 

for sources to use for drinking water supply (for example, 

Camp, Dresser, and McKee, 1965). The hydrogeologic units 

supplying groundwater to the public supply wells, irrigation 

wells, and to a lesser extent domestic wells are primarily 

the sands and gravels of the ice-contact and marine deltaic 

deposits (including both the deposits mapped as “ice-frontal 

marine delta” and “distal delta” deposits) and nearshore 

marine deposits (fig. 2). The distal deltaic deposits have been 

explored for public supply purposes and have previously 

been used for irrigation (D’Amore, 1984; Scott J. Minor, 

oral commun., 2011) but currently supply only domestic 

wells. Since 1992, the Maine Department of Conservation, 

Maine Geological Survey has been delineating sand and 

gravel glacial deposits in the State that are determined to be a 

“significant” aquifer, based on field observations of surficial 

materials, wells, test borings, municipal well inventories, well 

driller reports, and geophysical investigations. The significant 

sand and gravel aquifers have been mapped at a scale of 

1:24,000 (Neil and Smith, 1998a–d). A “significant” aquifer is 

one having the potential to yield 10 gallons per minute 

(gal/min) or more of water to a properly constructed well. 

In some areas, a thin layer (usually less than 10 ft) of waterbearing sand and gravel material may be readily identifiable 

on the surface, but if that area was determined as unable to 

sustain a yield of 10 gal/min or more (because it is not fully 

saturated or too small in area), that area was not mapped as 

an aquifer. Conversely, if materials with poor water-bearing 

properties overlie coarse-grained sediments, the underlying 

deposit may not have been recognized as a potentially 

significant aquifer (Dudley, 2004). Figure 1 shows the 

significant sand and gravel aquifers mapped for this study area 

(Neil and Smith, 1998a–d) expected to yield (a) 10–50 gallons 

per minute and (b) more than 50 gallons per minute to a 

properly constructed well. The delineated aquifers in the study 

area do not include the buried valley sand and gravel deposit 

underlying the coastal plain area in Kennebunk and Wells.

Hydraulic Properties

Published estimates of the hydraulic properties (transmissivity or hydraulic conductivity) of the hydrogeologic units 

in the study area are available from several studies (table 2). 

These estimates are based on calibrated groundwater modeling 

studies, aquifer tests, grain-size analysis, slug tests (singlewell tests) and other sources. Many of these studies were 

summarized in Nielsen and Locke (2011) and were done in 

areas with hydrogeologic units similar to those found in the 

study area.

Investigations into the hydrogeology of the sand and 

gravel aquifers in the study area have been limited to the 

sand and gravels in the central and western part of the study 

area. The high-yielding aquifer in the town of Sanford has 

been studied during the process of expanding the municipal 

water supply and also in protecting it from local point-source 

contamination sites (Camp, Dresser, & McKee, Inc., 1965; 

Whitman and Howard, Inc., 1981; Whitman and Howard, Inc., 

1984; Robert G. Gerber, Inc., 1993). Pump tests in the coarse 

sandy ice-contact deposits (mapped as ice-frontal marine delta 

deposits, fig. 2) yielded transmissivities ranging from 62,000 

to 82,000 gallons per day per foot (gpd/ft), or 80–150 feet 

per day (ft/d) hydraulic conductivities (saturated thicknesses 

ranging from 70 to 100 ft). Farther east, in the central part of 

the Branch Brook watershed (mapped as distal delta deposits, 

fig. 2), the aquifer has been studied for its use for the irrigation 

of blueberries in the past and was considered for possible use 

for bottled water extraction (Robert G. Gerber, 1981; Caswell, 

Eichler, and Hill, Inc., 1989; Caswell, Eichler, and Hill, 

Inc., 1995a; Caswell, Eichler, and Hill, Inc., 1995b; CEHJacques Whitford, 1997; GS Environmental and Groundwater 

Associates, Inc., 2002). These studies reported pump tests 

yielding transmissivities ranging from 6,000 to 13,000 gpd/ft 

or hydraulic conductivities of 40–90 ft/d (saturated thicknesses 

ranging from 16 to 20 ft). Single-well tests on monitoring 

wells with shorter screens yielded hydraulic conductivities 

ranging from 0.8 to 78 ft/d (median of nine tests was 6.4 ft/d) 

(Caswell, Eichler, and Hill, Inc., 1989). The discrepancy 

between the single-well tests and the pumping tests suggests 

that there is considerable heterogeneity in the stratified sand 

and gravels in this part of the study area and that an average 

effective hydraulic conductivity for the whole area may be 
Groundwater and Surface-Water Resources 11

Table 2. Hydraulic properties of hydrogeologic units in the area in and around the Branch Brook watershed in southern Maine.

[ft/d, foot per day; K, hydraulic conductivity; --, not applicable]

Hydrogeologic unit, 

location

Horizontal hydraulic 

conductivitiy, 

in ft/d

Vertical hydraulic 

conductivity, 

in ft/d

Source Method

Very fine to medium sand, 

with some silt (similar to 

marine nearshore sands), 

Fryeburg, Maine

2 to 5 -- Tepper and others (1990) Model

Marine nearshore sandy 

deposits, Freeport aquifer

-- -- Nielsen and Locke (2011) Model

Presumpscot Formation silt/

clay (unweathered), central 

Maine

6.2 × 10-3 (mean of 

32 measurements)

1.4 × 10-4 to 5 × 10-6

(range of three 

methods)

Brainerd and others (1996) Movement of natural 

tracers, age dating, 

rising-head tests

Presumpscot Formation silt/

clay, Saco, Maine

-- 2.7 × 10-5 Nielsen and others (1995) Movement of natural 

tracers

Presumpscot Formation silt/

clay (several sites)

-- 1.2 × 10-4 to 5 × 10-4 Gerber and Hebson (1996) Models–compilation of 

several studies

Stratified outwash sands, 

Oxford, Maine

15 to 80 -- Morrissey (1983) Model

Sand and gravel deposits in 

and near the Branch Brook 

watershed (central and 

western portions of the 

study area)

40 to 170 (range from 

5 aquifer tests)

-- Whitman and Howard, Inc., 

(1981), Caswell, Eichler, and 

Hill, Inc. (1995a), Caswell, 

Eichler, and Hill, Inc. (1995b), 

GS Environmental and 

Groundwater Associates (2002)

Aquifer tests

Sand and gravel in the central 

Branch Brook watershed 

area

0.8 to 78 (median 

6.4) from 9 singlewell aquifer tests

-- Caswell, Eichler, and Hill, Inc. 

(1989)

Slug tests

Till, Bald Mountain, Maine 0.045 to 0.91 -- Gerber and Hebson (1996) Model

Till, Fryeburg, Maine 4 -- Morrissey (1983) Model

Till, Freeport Aquifer 0.69 -- Nielsen and Locke (2011) Model

Fractured crystalline bedrock, 

Connecticut

0.5 -- Melvin and others (1995) Model

Fractured bedrock aquifer, 

Meddybemps, Maine

Less than 0.01 ft/d -- Lyford and others (1998) Model

Fractured bedrock, Corinna, 

Maine

0.1 to 1 ft/d -- Mack and Dudley (2001) Model
12 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

lower than the pump tests suggest if the lower hydraulic 

conductivity (K) parts of the aquifer materials are widespread.

Streambed and riverbed hydraulic conductivities typically 

are not measured in the field. Values used in other groundwater modeling studies in Maine and New England range from 

0.02 ft/d (Nielsen and Locke, 2011) and 1 ft/d (DeSimone, 

2004) to 2–5 ft/d (Tepper and others, 1990).

Recharge

Recharge in the study area has been estimated but not 

directly measured. D’Amore (1984) reported an estimated 

recharge amount of 47 percent of precipitation using an 

energy-balance method. The theoretical maximum amount of 

shallow recharge to sandy soils is about 25 inches per year 

(in/yr), based on the Lyford and Cohen (1988) method, or 

about 54 percent of precipitation. However, more recent 

studies of the hydrogeology in the study area determined 

recharge to the sandy aquifer in the Sanford outwash plain 

area to be very high for Maine, on the order of 60 percent 

or more of total precipitation (Gerber and Hebson, 1996; 

Robert G. Gerber, Ransom Environmental Services, Inc. 

[retired], oral commun., 2013). Nielsen and Locke (2011) 

reviewed the literature on recharge to several hydrogeologic 

units in southern Maine and New Hampshire with hydrologic 

settings similar to the study area, including till, the siltclay Presumpscot Formation, and sand and gravel deposits. 

Recharge to the groundwater flow model developed for the 

Freeport aquifer (Nielsen and Locke, 2011) ranged from 

5 inches in till and shallow bedrock areas to 25 inches in the 

sandy surficial aquifer areas. Published values of recharge into 

the Presumpscot Formation have been summarized by Gerber 

and Hebson (1996). Table 3 summarizes available information 

on recharge to the various hydrogeologic units in the Branch 

Brook-Merriland River study area.

The presence of unsewered suburban housing developments could add to the total amount of recharge entering the 

unsaturated zone in some locations. Houses in the study area 

that are not served by public water supply use either deep 

bedrock wells or shallow dug wells for their water supply, 

which is largely returned to the subsurface by way of individual septic systems. Although this process does not change 

the overall recharge rate, it could act to move water from the 

bedrock aquifer into the unsaturated zone, effectively increasing the local recharge rate to the uppermost hydrogeologic 

units. Most houses in the study area use dug wells in the shallow sandy aquifer, so the overall potential increase in recharge 

to the upper sandy units from septic systems is likely to be 

very small. 

Groundwater Levels

Historical groundwater level measurements in the study 

area are reported in well logs and some of the consultant’s 

reports, but these are not widely distributed across the study 

area and cover different time periods. Additional water-level 

data are available from a long-term groundwater monitoring 

well (well ME-YW 807) and from a one-time synoptic waterlevel survey that was conducted for this study in June 2012. 

Monthly groundwater levels in eight wells in the study area 

were published for 5 months in 1981–1982 (Tolman and others, 1983), but the wells were not clearly located.

Long-Term Groundwater Levels

The USGS operates a long-term groundwater monitoring 

well tapping the unconfined aquifer in the middle of the study 

area (well no., ME-YW 807, site ID 432310070393301), having periodic data going back to 1988. Groundwater levels for 

this well can be retrieved by visiting the USGS Groundwater 

Watch web page (http://groundwaterwatch.usgs.gov). Daily 

water levels in this well are available from the current time 

(2014) back to October 1989. Figure 5 shows the monthly 

water-level statistics for this well for the period of record. The 

median monthly water levels range from 17 to 19.5 feet below 

land surface, a relatively narrow range that reflects the abundant recharge and coarse-natured aquifer in this area.

Table 3. Recharge rates to unconsolidated and shallow bedrock aquifer materials in southern Maine from previously published studies. 

[in/yr, inches per year]

Hydrogeologic unit

Recharge rates reported 

in literature (from Nielsen 

and Locke, 2011), 

in/yr

Recharge rates in calibrated 

groundwater flow model, 

Freeport Aquifer (Nielsen 

and Locke, 2011), 

in/yr

Recharge rates from 

other investigations2 in 

the Branch Brook area, 

in/yr

Shallow bedrock 2 to 111 5 1 to 2.5

Till 3.5 to 8 5 to 7 2.5 to 5

Presumpscot Formation silt/clay (fresh, unweathered) 0.5 to 1.9 0.75

Sand and gravel deposits 22 to 25 24 to 25 19 to 28

1

Values originally from Nielsen (2002).

2

Investigations include D’Amore (1983), Robert G. Gerber, Inc. (1981), Robert G. Gerber, oral commun., 2013.
Groundwater and Surface-Water Resources 13

EXPLANATION

Percentile ranges

Greater than 90

76 to 90

25 to 75

10 to 24

Less than 10

Long-term 

monthly median

June and July

monthly mean, 2012

10

12

14

16

18

20

22

24

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

Depth to water level, in feet below land surface

Month

Water-level elevation in well, in feet above North

American Vertical Datum of 1988

200

198

196

194

190

192

188

Figure 5. Long-term monthly water-level statistics for the U.S. Geological Survey groundwater monitoring well ME–YW 807 in 

Sanford, Maine.

Synoptic Water-Level Survey

A synoptic survey of groundwater levels was conducted 

in late June 2012 to use for calibration points in the model. 

This time period was chosen because water levels in June and 

July are normally very close to the annual average water levels 

in this area, as determined using the ME-YW 807 well (fig. 5) 

and other USGS sand and gravel monitoring wells in Maine. 

In the case of June–July 2012, water levels were slightly 

above the average (fig. 5). Precipitation that occurred in the 

week prior to the water-level survey resulted in water levels 

that were generally rising during the week of the survey.

The water-level measurements for this survey were 

collected from a combination of monitoring wells and 

homeowner wells (fig. 6). The monitoring wells included 

wells established by the KKWWD and SWD for periodic 

monitoring of groundwater levels near their current pumping 

wells but also in areas that had been considered for other 

pumping wells. Monitoring wells for some chemical 

contamination sites in Sanford were included in this survey, 

along with the ME-YW 807 long-term monitoring well. In 

total, water levels in 96 monitoring wells were measured 

between June 21 and June 29, 2012, for this effort, along 

with water levels in 34 homeowner wells (23 dug wells and 

11 bedrock wells). The 10 wells used for a Maine Department 

of Environmental Protection (DEP) contamination-monitoring 

study in Sanford were measured on May 23, 2012 (Matthew 

Reynolds, written commun., 2012). Overall, 130 wells were 

measured for this effort (wells are listed in appendix 1). 

The homeowner wells were measured by USGS staff, and 

the monitoring wells were measured by a combination of 

USGS staff, water district employees, Maine DEP and MGS 

employees, and a consultant hired by the KKWWD. Waterlevel measurement training was provided to all personnel 

involved in the water-level survey.

Water levels during the synoptic survey ranged from 

within 0.1 ft of the land surface to more than 58 ft below land 

surface. The water-level elevations ranged from a high of 

230–232 ft in the water-table aquifer in the Sanford area to 

15 ft below sea level in the (confined) buried aquifer near the 

Merriland River pumping well. Water levels in the sand and 

gravel monitoring wells averaged about 14–16 feet below land 

surface in the Sanford and central Branch Brook watershed 

areas. A limited number of shallow-deep well pairs indicated a 

slight downward gradient in the Sanford area and the area just 

north of Branch Brook, and a stronger downward gradient in 

the sand plain to the south of Branch Brook. Wells in the headwaters of Branch Brook indicated an upwards hydraulic gradient. In the areas around the pumping wells in the southeastern 

part of the study area, water levels averaged more than 33 ft 

below land surface in the upper unconfined sand and gravel 

aquifer and more than 42 ft below land surface in the confined 

aquifer near the Merriland River pumping well. The only shallow-deep well pairs near the Harriseckett and Plant wells were 

too close to the pumping wells to determine a representative 

hydraulic gradient. Water levels in a shallow-deep well pair 

800 ft from the Merriland well indicated a strong downward 
14 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

k

k

kk

k

k

k

k

01069500

01069780

01069785

01069700

01069720

01069505

01069515

01069580

01069725

01069690 01069680

01069640

01069645

01069660

ME-YW807

Watershed boundaries

Long-term groundwater 

observation well

Continuous streamgage

Partial record streamgage site

Groundwater measurement sites, by type

Homeowner well, bedrock

Homeowner well, till

Homeowner well, sand/gravel

Monitoring well, sand/gravel

Wetland or surface-water body

ME-YW807

01069780

01069700 Production well, and pumping rate in gallons per minute

6 to 20

21 to 500

501 to 1000

Groundwater model

Model boundary

Active model boundary

EXPLANATION

Branch Brook

Cold Water Bk.

0 10.5 2 3 4 KILOMETERS

0 0.5 1 2 3 4 MILES Water bodies, watersheds, towns, and roads from U.S. Geological Survey digital line graphs 1:24:000, 2010.

North American Datum of 1988

Universal Transverse Mercator projection

State plane Maine West FIPS 1802 coordinate system

Perkins Marsh Bk.

Day Brook

Merriland River

Atlantic 

Ocean

Little River

Mo u sam River

Mousam River

Branch Brook

Figure 6. Locations of groundwater and streamflow measurement sites in the area in and around the Branch Brook watershed 

in southern Maine from 2010 through 2012.
Groundwater and Surface-Water Resources 15

gradient. Water levels in the homeowner wells were generally 

shallower; water levels in the till and sandy aquifer dug wells 

averaged less than 5 ft below land surface. In bedrock wells, 

water levels averaged 16 ft below land surface. There were no 

well pairs that included bedrock wells.

Groundwater Flow System

The groundwater levels and geometry of the surfacewater system indicate the general groundwater flow directions 

within the study area, whereas the hydrogeologic units are 

defined by the surficial geology. The groundwater flows generally from west to east, following the overall topographic trend, 

and from the topographic highs between rivers and streams 

towards the closest surface-water feature. 

In the western part of the study area (Sanford area), the 

sand and gravel deposits are quite thick (60 ft to over 100 ft; 

see figs. 3 [cross-section A–A′] and 4). The Mousam River 

acts as a regional groundwater discharge zone in this area, and 

groundwater generally flows towards the closest surface-water 

body. There is no large-scale confining unit, although silt/clay 

lenses are interspersed in the sand and gravel. A groundwater 

divide exists somewhere between the headwaters of Branch 

Brook and the Mousam River. Because the surface of the 

outwash delta deposits has such low relief, the location of the 

groundwater divide is not well defined by the surface topography. Another groundwater divide separates groundwater flowing to the headwaters of Branch Brook from water flowing to 

the headwaters of the Merriland River. Similarly, its location is 

not well-defined by the surface topography (fig. 1). 

In the Branch Brook watershed, the Presumpscot Formation fills a deep bedrock valley (fig. 4A), and the significant 

aquifer materials are deposited in a 30- to 50-ft thick sandy 

unit above the Presumpscot Formation. The saturated thickness of these units ranges from 10 to approximately 40 ft. 

Branch Brook itself is incised completely through the sand and 

gravel and into the Presumpscot Formation, and groundwater 

flows towards the river, discharging in springs and short, steep 

tributaries incised into the sand and gravel. Recharge percolates through the surficial sandy soils to the water table. North 

of the Branch Brook watershed, the shallow groundwater discharges to tributaries to the Mousam River and to the Mousam 

River itself, which forms a regional groundwater divide. The 

Presumpscot Formation acts as a significant barrier to vertical 

groundwater flows between the surficial aquifer and bedrock 

in the central part of the study area (fig. 3).

In the headwaters of the Merriland River watershed, 

groundwater flow is considered to be from northwest to 

southeast, based on the topography and location of the mapped 

sand and gravel aquifer materials and location of streams. 

However, some groundwater may flow directly to the east, 

towards Branch Brook (which is topographically lower than 

the Merriland River headwaters), and some groundwater may 

flow south across the watershed boundary where the mapped 

sand and gravel aquifer straddles the watershed boundary in 

the southern part of Sanford (fig. 1). There were not enough 

groundwater wells in this area to determine flow directions 

independently. Groundwater in the rest of the Merriland River 

watershed exists in thin sand or till deposits over bedrock or 

in thicker till, neither of which are significant groundwater 

resources. Groundwater flow is generally from the upland 

areas towards the nearest surface-water body.

The central part of the study area is separated from the 

coastal plain by a northeast-southwest trending bedrock ridge, 

through which the Merriland River, Branch Brook, and the 

Mousam River flow (fig. 2). This bedrock high limits shallow 

groundwater flow towards the ocean and the coastal plain, as 

the shallow sandy aquifer material in the Branch Brook and 

Mousam River valleys is severely constricted in this area. 

East of the bedrock high, the topography is relatively flat, 

and the three river valleys flatten and join in the coastal plain 

area, discharging to the ocean quite close to one another. In 

this area (generally east of Interstate-95, fig. 1), groundwater 

is found in shallow, unconfined aquifer areas and in a deeper 

sand and gravel aquifer underneath the coastal plain. 

The shallow sediments in the coastal plain are a layered 

mix of coarse to fine sand and silt and clay. They are coarsest 

near the bedrock ridge and get progressively finer towards the 

ocean. The surficial sandy units are approximately 20 to 50 ft 

thick over the Presumpscot Formation. In some places, mucky 

peat overlies the silt and clay of the Presumpscot Formation instead of sand. At depth, a deep buried valley is at least 

partially filled with coarse sand and gravel. This is largely 

covered with the silt and clay of the Presumpscot Formation, 

which forms a partial confining unit that overlies much of 

this aquifer (figs. 3 and 4). The extent of this sand and gravel 

deposit is not well mapped, but from well logs it appears to 

trend in a northeast-southwest direction. Seismic lines were 

used to help identify the extent of the bedrock valley but could 

not be used to determine the nature of the sediments filling the 

valley. The source of recharge to this unit, which is used as 

a drinking water supply by the local water utility, is not well 

defined. On the basis of pumping and water-level records on 

file with the local water utility, this sand and gravel deposit is 

at least partially connected to the shallower coarse sands near 

the bedrock high (to the west-northwest) and extends south 

beyond the Merriland River watershed boundary.

On the southwest side of Branch Brook, water levels 

are 20–40 ft below land surface, and natural flow gradients 

are somewhat disrupted by the Harriseckett and Plant pumping wells, but flow gradients are still generally towards the 

Merriland River and Branch Brook surface-water features. 

Between Branch Brook and the Mousam River, the water 

table gradients are particularly flat, and the water table is quite 

shallow. Much of this area is covered by forested wetlands 

because of the high water table and, in some areas, because 

of the presence of the Presumpscot Formation silt/clay, which 

retards vertical groundwater movement. Beneath the Presumpscot Formation in the buried gravel aquifer, the groundwater 

flow is affected primarily by the Merriland River pumping 

well, which draws groundwater from both the north and south 

within this aquifer. 
16 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

Groundwater in the bedrock units in the study area is 

assumed to discharge to the local surface-water bodies (rivers 

and streams or the ocean) where the Presumpscot Formation 

does not directly overlie the bedrock and act as a barrier to 

flow. There is little evidence indicating whether or not there 

is groundwater exchange between the bedrock units and the 

surficial aquifers in the study area. Although there is a large 

regional fault system that crosses the study area, it is just as 

likely to act as a barrier to bedrock groundwater flow as it 

is to act as a conduit. There are no data to indicate that the 

fault system affects the surficial aquifers in any particular 

manner. Besides this feature, it is expected that there would 

be some small amount of groundwater interaction between the 

coarse-grained units that overlie the bedrock and the shallow 

bedrock but an insignificant amount of interaction where the 

Presumpscot Formation overlies the bedrock.

Surface-Water Resources

There are three primary rivers within the study area. They 

are, from north to south, the Mousam River, which defines the 

northern boundary of the study area; Branch Brook; and the 

Merriland River, which is farthest to the south. The Branch 

Brook and Merriland River watersheds (13.4 and 17.3 mi2, 

respectively) together cover most of the study area and are of 

primary concern in this study. The remainder is the part of the 

Mousam River watershed that falls between the Branch Brook 

watershed and the Mousam River itself to the north. (figs. 1 

and 6). The USGS has operated a streamgage on the Mousam 

River (station 01069500) from 1939 to 1985 and 2008 to 

the present (2014) and has operated a streamgage on Branch 

Brook (station 01069700) since 2008. In order to better 

understand the groundwater–surface-water interactions within 

the study area, 12 additional streamflow monitoring sites were 

established for this study (fig. 6) and are described below.

Streamflow monitoring sites were established on the 

Merriland River, Branch Brook, and tributaries to the Mousam 

River (fig. 6). Approximately 16 measurements were made 

at each of these sites during 2010–11 (table 4). Six separate 

locations along Branch Brook were measured between U.S. 

Route 1 (fig. 1) and the headwaters (including the USGS 

streamgage [station 01069700] and stations 01069640, 

01069645, 01069660, 01069690, and 01069720). Two 

tributaries to Branch Brook also were measured (stations 

01069680 and 01069725). Two sites on the Merriland River 

were measured, one above the confluence with Branch Brook 

and the Little River (station 01069785) and the other about 

1.5 miles upstream (station 01069780). The Merriland River 

pumping well is located between these two sites. Finally, three 

tributaries to the Mousam River were measured—Day Brook 

Table 4. Streamflow measurement site information, Mousam River, Branch Brook, and Merriland River watersheds in southern Maine 

from 2010 through 2012.

[ID, identification number; USGS, U.S. Geological Survey; mi2, square miles; ft3/s, cubic feet per second; --, not applicable; S., south; ME, Maine; Trib, tributary; Br., brook; nr, near; Rte, U.S. Route; R., river]

Station 

number Local ID Station name

USGS 

continuous gaging 

station

Drainage 

area 

(mi2)

Number of 

measurements 

(2010–12)

Range in 

measured 

streamflows 

(in ft3/s)

Mousam River Watershed

01069505 Perkins Marsh Perkins Marsh Brook near South Sanford, Maine -- 2.74 17 0.77–8.59

01069515 Cold Water Cold Water Brook near Kennebunk, Maine -- 0.84 16 1.46–2.88

01069580 Day Brook Day Brook at Whitten Road near Kennebunk, Maine -- 1.78 16 .87–5.08

Branch Brook Watershed

01069640 BB#7 Branch Brook near South Sanford, Maine -- 1.41 16 .31–11.03

01069645 BB#6 Branch Br. at Sam Allen Hill Rd., S. Sanford, ME -- 1.74 17 .48–10.81

01069660 BB#5 Branch Brook near Saywards Corner, Wells, Maine -- 3.51 17 2.48–17.8

01069680 BB#4 Trib to Branch Br. nr Hobbs Crossing, Wells, ME -- 1.17 17 .23–3.21

01069690 BB#3 Branch Brook near Wells, Maine -- 7.60 17 7.67–24.8

01069700 BB#2 Branch Brook near Kennebunk, Maine Yes 9.67 --

01069720 BB#1 Branch Br. at Post Rd (Rte 1), Kennebunk, Maine -- 11.6 18 .04–33.0

01069725 BB#8 Trib to Branch Br. at Post Rd (Rte 1) nr Wells, ME -- 1.04 17 .22–4.29

Merriland River Watershed

01069780 Merri#2 Merriland River at Coles Hill Rd nr Wells, Maine -- 15.8 16 2.76–41.5

01069785 Merri#1 Merriland R. at Skinner Mill Rd near Wells, Maine -- 16.7 16 2.07–33.6
Groundwater and Surface-Water Resources 17

(station 01069580), Cold Water Brook (station 01069515), 

and Perkins Marsh Brook (station 01069505). These three 

flow generally northward from the edge of the Branch Brook 

watershed to the Mousam River. All these sites were measured 

to gain an understanding of how groundwater discharge was 

distributed geographically around the study area to use in 

calibrating the groundwater flow model.

Streamflow Measurements

Between 15 and 17 measurements representing a range 

of flows were obtained at each station (table 4) so that mean 

monthly flow estimates and base-flow estimates could be 

computed for each site. Most sites had 16 measurements completed. All the measurements were made following standard 

USGS techniques, using a pygmy meter, AA meter, or a 3-inch 

modified Parshall flume (Rantz and others, 1982). Measurements were made between June 1, 2010, and April 7, 2012, 

with more measurements being made during the summer 

than during the spring and fall. No measurements were made 

between the middle of November and April during this period. 

The flows measured ranged from low summer flows through 

high flows in the spring and fall. At the most downstream 

measurement site on Branch Brook (BB#1, station 01069720, 

at the U.S. Route 1 bridge), measurements were made downstream from the intake for surface-water withdrawals. The 

amount of withdrawal was added back to the measured flows 

to obtain the flow at that site before the withdrawal.

A summary of the measurements taken along Branch 

Brook is shown in figure 7. The flows for a representative 

selection of dates are plotted in downstream order at each of 

the Branch Brook measurement sites, illustrating the downstream accumulation of flow from the uppermost site (BB#7, 

station 01069645) to the most downstream site (BB#1, station 

01069720) to the intake just below BB#1. Flows increase in 

a linear manner all along the length of the stream until the 

segment between BB#2 (USGS streamflow gage, station 

01069700) and BB#1 where the increase in flow slows down.

The Branch Brook streamgage (station 01069700) has not 

been operating long enough to collect long-term statistics, but 

the mean annual flow for 2011–13 was 21.6 ft3/s. The mean 

annual flow at the Mousam River site (station 01069500) for 

the same years was 201 ft3/s, as compared to the long-term 

mean of 188 ft3/s; this suggests that the data-collection time 

period was somewhat wetter than average for the study area.

Although the total runoff in cubic feet per second per 

square mile (ft3

/mi2) from Branch Brook is similar to the State 

average (2.24 ft3/mi2 in Branch Brook at station 01069700 for 

water years1

 2011–2013, compared to the statewide median 

for water years 2011–2013 of 2.34 ft3/mi2), a larger percentage 

of that runoff likely occurs as groundwater discharge (base 

flow) rather than as direct runoff from precipitation events 

because of the coarse-grained soils and small number of 

1

A water year is the 12-month period from October 1 to September 30. It is 

designated by the year in which it ends. 

surface tributaries in the watershed. The groundwater model, 

described in the section on the simulation of groundwater flow 

later in this report, can simulate groundwater discharge (base 

flow) but not direct runoff from individual precipitation events 

nor total runoff (base flow plus direct runoff).

Calculation of State Requirements for In-stream 

Flows

The in-stream flow requirements (seasonal aquatic base 

flows) for the State of Maine (also known as the Chapter 587 

rules) are designed to protect the aquatic health of riverine 

ecosystems and vary with the seasons (Maine Department of 

Environmental Protection, 2007). The State uses estimates of 

natural monthly flows, sometimes combined with site-specific 

geomorphic analysis, to evaluate streamflow requirements 

in support of aquatic habitat where a proportionally large 

withdrawal is identified in a watershed. The in-stream 

flow requirements are specific to six time periods—winter 

(January 1 to March 15), spring (March 16 to May 15), early 

summer (May 16 to June 30), summer (July 1 to September 

15), fall (September 16 to November 15), and early winter 

(November 16 to December 31); each of these is based on 

estimates of median monthly streamflows. Chapter 587 states 

that, without site-specific flow data, the monthly median 

flows can be determined by using statewide flow equations 

developed by Dudley (2004). These equations use watershed 

characteristics (such as area and precipitation) to estimate 

monthly median flows and confidence intervals around those 

estimates. The State requirements also indicate that sitespecific hydrologic data may be used to calculate the monthly 

median flows. Site-specific estimates of the median monthly 

flows is likely better suited to the specific site than the 

statewide equations (Nielsen and Locke, 2011). 

For this study, a comparison was made between the instream flow requirements calculated from the statewide equation estimates of monthly median flows and monthly median 

flows calculated using site-specific data at the farthest downstream measurement sites in Branch Brook and the Merriland 

River (stations 01069725 and 01069785).

Monthly Median Streamflows and In-stream Flow 

Requirements Based on Statewide Flow Equations

The equations in Dudley (2004) were used to derive 

estimates of monthly median flows at stations 01069720 and 

01069785 using watershed data given in table 5. Both watersheds have similar areas, precipitation amounts, and distances 

from the Gulf of Maine line, but differ dramatically in the percentage of mapped sand and gravel aquifers (table 5, fig. 1). 

This manifests primarily in the summer median monthly flows 

(table 6), as the differences in fall and winter median flows are 

driven by differences in drainage area size.

The six seasons that are defined in the Chapter 587 

requirements are winter, spring, early summer, late summer, 

fall, and early winter. The streamflow requirements for those 
18 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

BB#7

BB#6

BB#5

BB#3

BB#2

BB#1

Below intake

0

5

10

15

20

25

30

35

40

45

0 2 4 6 8 10 12 14 16 18

Streamflow, in cubic feet per second

Distance along Branch Brook, in miles

6/29/2010

7/16/2010

7/29/2010

8/11/2010

11/11/2010

4/22/2011

6/15/2011

Average of 16 

measurements

EXPLANATION

Measurement dates

Figure 7. Streamflows measured on Branch Brook for selected dates between April 2010 and August 2011, southern Maine.

Table 5. Watershed characteristics for the calculation of 

monthly median streamflows for Branch Brook and the Merriland 

River in southern Maine.

[For definitions and derivations of watershed characteristics, see Dudley 

(2004)]

Watershed characteristic

Branch 

Brook 

(01069720)

Merriland 

River 

(01069785)

Drainage area, in square miles 13.6 16.7

Distance from Gulf of Maine line, in miles 27 27

Percent sand and gravel aquifer 65.3 23.2

Annual precipitation, in inches 47.1 47.1

Winter precipitation, in inches 11.5 11.5

Table 6. Median monthly streamflows in Branch Brook and 

the Merriland River in southern Maine based on statewide 

equations. 

[ft3/s, cubic feet per second]

Month

Median monthly streamflows, in ft3

/s

Branch Brook 

(01069720)

Merriland River 

(01069785)

January 25.1 31.1

February 27.6 34.1

March 57.8 71.0

April 66.0 81.2

May 19.6 24.4

June 12.2 15.2

July 19.5 9.22

August 20.3 7.18

September 19.2 7.17

October 26.9 11.4

November 16.8 20.6

December 30.1 37.0
Groundwater and Surface-Water Resources 19

seasons are based on the median flows for the months of 

February, April, June, August, October, and December. The 

seasonal in-stream flow requirements based on the statewide 

equations for Branch Brook (at station 01069720) and the 

Merriland River (at station 01069785) are shown in figure 8. 

Note that the June median flow for Branch Brook deviates 

from a smooth transition between the spring and summer 

flows because the statewide equation for June does not include 

a term for the percentage of sand and gravel aquifers, although 

the later summer months do.

Monthly Median Streamflows Based on Site-Specific 

Streamflow Measurements

As stipulated in the Chapter 587 rules, site-specific data 

may be used to calculate median monthly flows. In this study 

area, the streamflow measurements described above were 

used with streamflow data from several continuous-record 

streamflow gages to estimate the monthly median flows 

using the MOVE.1 method (Hirsch, 1982), as was done in 

the Freeport aquifer study (Nielsen and Locke 2011). The 

MOVE.1 regression method (also called the line of organic 

correlation) is used to estimate statistics representing longterm data at a given site, using short-term data collected over a 

range of hydrologic conditions at that site and concurrent data 

collected at a long-term index site (Hirsch, 1982; Helsel and 

Hirsch, 2002).

Several index stations in western Maine and southern 

New Hampshire were tested for correlations with the 

streamflows collected at the Branch Brook and Merriland 

River sites. The best correlations for the MOVE.1 regression 

were obtained for index stations close to and within the 

study area (Mousam R. [station 01069500] and Branch 

Brook [station 01069700]) and southeastern New Hampshire 

(Bearcamp River at Tamworth, New Hampshire, station 

01064801). Whereas the correlation coefficients between 

the local sites and the Branch Brook streamgage were very 

high for both sites (greater than 0.90 for both locations), 

the Branch Brook streamgage does not have the minimum 

10 years of continuous record for an ideal index site. 

Therefore, the other two index sites were used with the Branch 

Brook streamgage to calculate the monthly flow statistics, 

which are an average of the estimates using two index 

sites (table 7). It should be noted that the median monthly 

streamflow estimates from the two index sites used for each 

location differ slightly from one another. For example, the 

Branch Brook site (station 01069720) and the Branch Brook 

streamgage (station 01069700) yield estimates that are 

equal to or lower than the estimates from the Mousam River 

streamgage (station 01069500). Once the Branch Brook 

streamgage has the minimum 10 years of streamflow required 

for a statistically stable index site, a recalculation of these 

values could yield median monthly streamflow estimates for 

station 01069720 that are slightly lower in some months. The 

converse, however, holds for the Merriland River—that is, the 

Branch Brook streamgage yields somewhat higher estimates 

than the Bearcamp River streamgage (station 01064801).

Comparison of Monthly Median Streamflows and Late 

Summer In-stream Flow Requirements Using the Two 

Methods

The monthly median flows calculated using the sitespecific data are considerably different from the median flows 

estimated from the statewide equations (fig. 9) for many 

months of the year. The annual hydrograph for Branch Brook 

calculated using the MOVE.1 technique is much flatter and 

shows much less variation than the annual hydrograph based 

on the statewide equations. The MOVE.1 annual hydrograph 

also does not display the same lack of smooth transitions from 

month to month seen in the statewide equation hydrograph. In 

the Merriland River, the annual hydrograph shows a similar 

degree of monthly variation using the two methods, but the 

MOVE.1 estimates are significantly lower for every month. 

However, as noted above, once the Branch Brook streamgage 

(station 01069700) reaches 10 years of continuous data, 

new calculations could raise the MOVE.1 estimates for the 

Merriland River.

The late summer season is normally the season with the 

lowest in-stream flow requirement, as it is typically the time 

of year when streamflows are lowest in Maine. The August 

median flow is used as the in-stream flow requirement for late 

summer if there is not a specific waiver or alternative-method 

flow established (such as a geomorphic analysis). The August 

median flow in the Merriland River was calculated as 7.18 ft3/s 

using the statewide equations but was 3.07 ft3/s using the 

MOVE.1 analysis. In Branch Brook, the August median flows 

were 20.3 ft3/s using the statewide equations (which is higher 

than the June median flow) and 11.8 ft3/s using the MOVE.1 

analysis. Clearly, in each case, using site-specific data yields 

an estimate of the August median flow that is much lower than 

the statewide equations provide. Using site-specific data provides target median flows that are closer to actual conditions 

in the local streams than what the statewide equations provide 

and which would therefore be easier for a regulated utility to 

maintain for meeting in-stream flow requirements.

Because the statewide equations (Dudley, 2004) are predictions based on a statistical analysis of many other watersheds, the predicted residual sum of squares (PRESS) statistic 

can be used to calculate prediction intervals for each month, 

as well as the individual monthly predicted value (Dudley, 

2004; Riggs, 1968). The prediction intervals (table 8) indicate the level of certainty surrounding the individual monthly 

predicted value. The flows bounded by the prediction interval 

would be expected to contain the actual (measured) flow for 

a given stream 90 percent of the time. The monthly median 

streamflows estimated using the record extension method 

(MOVE.1) for Branch Brook fall well within the 90-percent 

prediction intervals only for the months January, July, and 

November (table 8). The rest of the time, the MOVE.1 flows 

are either outside the 90-percent prediction interval or near the 
20 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

0

10

20

30

40

50

60

70

80

90

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

Streamflow, in cubic feet per second

Month

Winter

Branch Brook seasonal aquatic in-stream flows

Branch Brook monthly median streamflows 

from statewide equations

Merriland River seasonal aquatic in-stream flows

Merriland River monthly median streamflows 

from statewide equations

EXPLANATION

Spring

Early 

summer

Late summer

Fall Early

winter

Figure 8. Seasonal aquatic in-stream flow requirements calculated for Branch Brook and the Merriland River in southern 

Maine from statewide equations.

Table 7. Median monthly flows in Branch Brook and the Merriland River in southern Maine based on site-specific streamflow data 

and regressions with local index sites.

[ft3/s, cubic feet per second; R., River]

Month

Branch Brook (01069720) median monthly streamflows, 

in ft3

/s 

Merriland River (01069785) median monthly streamflows, 

in ft3/s

Based on index sites Mean of Branch 

Brook and Mousam 

R. medians

Based on index sites Mean of Branch 

Brook and Bearcamp 

R. medians

Mousam R. gage 

(01069500)

Branch Brook gage 

(01069700)

Bearcamp R. gage 

(01064801)

Branch Brook gage 

(01069700)

January 25.7 20.2 23.0 9.63 12.1 10.9

February 26.0 20.2 23.1 7.82 12.1 10.0

March 33.5 34.2 33.9 19.3 43.7 31.5

April 42.2 35.3 38.8 34.2 47.2 40.7

May 30.1 24.5 27.3 18.4 19.4 18.9

June 22.5 22.4 22.4 7.58 15.5 11.5

July 15.7 15.9 15.8 4.13 6.77 5.45

August 12.0 11.6 11.8 2.99 3.15 3.07

September 13.8 12.2 13.0 3.12 3.52 3.32

October 18.4 15.9 17.2 7.95 6.77 7.36

November 23.1 19.7 21.4 15.7 11.3 13.5

December 26.9 24.5 25.7 14.8 19.4 17.1
Groundwater and Surface-Water Resources 21

A. Branch Brook 

Streamflow, in cubic feet per second

Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.

0

10

20

30

40

50

60

70

80

90

Monthly median streamflows from

MOVE.1 analysis

Monthly median streamflows from

statewide equations

Direct withdrawals

Standard seasonal in-stream flow requirements

EXPLANATION

Winter Spring Early 

summer Late summer

Early 

Fall winter

B. Merriland River

Streamflow, in cubic feet per second

Jan. Feb. Mar. Apr. May June July Aug. Sept. Nov. Dec. Oct.

0

10

20

30

40

50

60

70

80

90

Standard seasonal in-stream flow requirements

Monthly median streamflows from

statewide equations

Monthly median streamflows from

MOVE.1 analysis

Winter

Spring

Early 

summer

Late summer Early 

winter Fall

EXPLANATION

Figure 9. Comparison of annual hydrographs for A, Branch Brook and B, the Merriland River in southern Maine using two 

estimation methods, and the standard seasonal aquatic in-stream flow requirements calculated using statewide equations.
22 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

Table 8. Comparison of monthly median streamflows for Branch Brook and the Merriland River in southern Maine.

[Prediction intervals for monthly median streamflows estimated using the Maine statewide equations from Dudley (2004) and monthly median streamflows 

were calculated using a record extension technique for Branch Brook and the Merriland River. For method of calculating prediction intervals, see Dudley 

(2004). MOVE.1, method of variance extension, type 1, see Hirsch (1982)]

Month

Branch Brook estimates, 

in cubic feet per second

Merriland River estimates, 

in cubic feet per second

Monthly median streamflow estimated 

using recordextension 

technique 

(MOVE.1)

Monthly 

median 

streamflow 

calculated using 

statewide 

equations

Upper 

90-percent 

prediction 

interval on 

statewide 

equation 

streamflows

Lower 

90-percent 

prediction 

interval on 

statewide 

equation 

streamflows

Monthly median streamflow estimated 

using recordextension 

technique 

(MOVE.1)

Monthly 

median 

streamflow 

calculated using 

statewide 

equations

Upper 

90-percent 

prediction 

interval on 

statewide 

equation 

streamflows

Lower 

90-percent 

prediction 

interval on 

statewide 

equation 

streamflows

January 23.0 25.1 34.3 18.4 10.9 31.1 42.4 22.7

February 23.1 27.6 36.0 21.2 10.0 34.1 44.4 26.1

March 33.9 57.8 81.8 40.9 31.5 71.0 100.4 50.2

April 38.8 66.0 99.4 43.8 40.7 81.2 122.3 54.0

May 27.3 19.6 28.8 13.3 18.9 24.3 35.9 16.5

June 22.4 12.2 18.9 7.8 11.5 15.2 23.6 9.8

July 15.8 19.5 33.0 11.6 5.5 9.2 15.6 5.5

August 11.8 20.3 36.1 11.4 3.1 7.2 12.8 4.0

September 13.0 19.2 32.8 11.2 3.3 7.2 12.3 4.2

October 17.2 26.9 48.4 14.9 7.4 11.5 20.6 6.4

November 21.4 16.8 30.6 9.2 13.5 20.6 37.6 11.3

December 25.7 30.1 39.0 23.2 17.1 36.9 47.9 28.5

edge of it, indicating that the Branch Brook watershed is quite 

different from most of the watersheds that were used to derive 

the statewide equations. The MOVE.1-calculated streamflows 

for the Merriland River are well below the lower 90-percent 

prediction interval for the statewide equations calculated for 

the Merriland River for the months of December through 

April (table 8). The MOVE.1 estimates for the months of May 

through November are very close to the lower 90-percent prediction intervals from the statewide equations. In the case of 

the Merriland River, the apparent over-prediction of monthly 

median streamflows by the statewide equations may be an artifact of the possibly low estimates from the MOVE.1 method, 

as suggested above, or it may be because the regression equations used in the statewide flow statistics calculations do not 

include all the watershed characteristics that together explain 

the actual streamflows. In either case, as an alternative method 

of calculating or estimating the monthly median streamflows 

at these two sites, the MOVE.1 method is more apt to provide 

estimates that are closer to values that would be obtained from 

a long-term streamgage because it uses data collected at each 

specific site, and that are therefore likely closer to the “true” 

values of monthly median streamflows. The MOVE.1 analysis 

also was used to estimate early summer base flows to use as 

calibration targets for the groundwater flow model described 

later in the report.

Water Use and Withdrawals

Withdrawals of water for human use include drinking 

water, industrial, commercial, and agricultural (irrigation and 

other agricultural uses) from wells and streams, and rural 

domestic use from homeowner wells. Large water withdrawals in the State of Maine are governed by several Maine laws, 

implemented by multiple State agencies. Maine’s In-Stream 

Flows and Lake and Pond Water Level Rules (Chapter 587) 

apply to most water withdrawals and are intended to protect 

natural aquatic life and other designated uses in Maine’s 

waters. Under Chapter 587 rules, withdrawals are not regulated (and are not reported) if they do not affect river or 

stream flows by a certain percentage (which varies by the U.S. 

Environmental Protection Agency water-quality classification) or if they do not affect water levels in a lake or pond by 

a certain amount. The State laws are aimed at protecting the 

natural resource by requiring that flows be maintained but 

do not require reporting of water withdrawals for most water 

users. Because comprehensive reporting is not required, data 

on water withdrawals are not always available for a given 

watershed, and estimates based on water use coefficients or 

other methods must be applied to account for all potential 

water withdrawals.
Water Use and Withdrawals 23

Sources of Water Use Data

This study used a combination of reported and estimated 

withdrawal data to obtain an estimate of the total amount of 

water withdrawal in the study area. Reported withdrawals for 

public supply were obtained from the Maine Drinking Water 

Program in 2010 (Andrews Tolman, written commun., 2010). 

Estimates of withdrawals for rural domestic use, agricultural 

use, and commercial/industrial use that is not connected to 

the public water supply were made using methods described 

below. Wastewater discharge data are from the U.S. Environmental Protection Agency (undated) National Pollution 

Discharge permits.

Reported Withdrawals

There were six public water suppliers in the study area 

in 2010 that reported withdrawals to the State of Maine. 

Four of these were small community systems serving mobile 

home parks or subdivisions with their own water supply, 

each serving a population of less than 200 persons. The other 

two, the SWD and the KKWWD, each serve relatively large 

populations of 14,000 and 31,400, respectively. The SWD 

withdraws groundwater from a single source within the study 

area (although they use several other groundwater sources 

outside the study area); the KKWWD withdraws a mix of 

surface water (from Branch Brook) and groundwater from 

multiple wells, one of which is outside the study area. The 

reported withdrawals for KKWWD are not broken down by 

source, so staff at the KKWWD provided information on 

withdrawals from each of the groundwater sources (Scott D. 

Minor, Assistant Superintendent, KKWWD, written commun., 

2013) and surface-water withdrawals. Commercial and 

industrial water users in the Sanford area generally are served 

by the Sanford Water District and are included in the public 

water supply category (table 9). In the KKWWD service area, 

there is little industrial activity, but commercial users within 

the service area are likewise included in the public water 

supply categories.

Estimated Withdrawals

Several methods were used to estimate other withdrawals 

in the study area. Domestic water usage from private wells 

was estimated using a geographic information system 

(GIS) analysis of houses located from high-quality aerial 

photography and maps of the extent of public water-supply 

service areas for the towns of Sanford, Kennebunk, and Wells. 

Rates of private water withdrawals were based on a perperson water use coefficient of 60 gal/d per person in Maine 

(U.S. Geological Survey water use compilation for Maine, 

unpub. data, 2010) and census data on the number of persons 

per household in each town (U.S. Census Bureau, 2010). 

Commercial and industrial water usage outside the publicsupply service areas was estimated using a combination of 

GIS mapping, internet searches, and a commercially available 

business database (HarrisInfosource) to locate businesses, 

and the application of water-use coefficients for New England 

(Horn, 2000; Horn and others, 2007) for different types of 

industrial and commercial uses. Agricultural water use was 

estimated using information on irrigated acreage in the study 

area from the Maine Department of Environmental Protection 

(J. Harker, written commun., 2010), internet searches of farms 

in the study area, and irrigation rates determined for 2010 in 

the 2010 U.S. Geological Survey water use compilation for 

Maine (U.S. Geological Survey water-use compilation for 

Maine, unpub. data, 2010). Personal reconnaissance also was 

used to identify other water withdrawals (a fish hatchery).

Reported and Estimated Withdrawals in the 

Study Area

Surface-water withdrawals in the study area in 2010 were 

primarily withdrawals from Branch Brook by the KKWWD 

in the amount of 590 Mgal (2.63 ft3/s). Agricultural irrigation 

from surface-water ponds was estimated to be about 9 Mgal.

Groundwater withdrawals account for the remainder of 

the withdrawals. These include the permitted public water 

supplies, domestic water use, commercial and industrial 

water use, and other agricultural water use (table 9). In 2010, 

permitted public water-supply withdrawals totaled 384.3 Mgal 

in the Merriland River watershed, 231.5 Mgal in the Mousam 

River watershed, and 32.2 Mgal in the Branch Brook 

watershed, for a total of 658.8 Mgal (2.79 ft3/s). Domestic 

withdrawals from a total of 1,751 residences identified from 

aerial photos were split fairly evenly among the watersheds: 

32.2 Mgal in the Merriland River watershed, 32.1 in the 

Mousam River watershed, and 24.6 in the Branch Brook 

watershed, with a small amount (0.15 Mgal) in the coastal 

areas (table 9). Domestic wells in the study include those using 

bedrock, till, and the sandy surficial aquifers. Of the domestic 

withdrawals, estimates of the percent that percolates back into 

the subsurface through individual septic systems range from 

84 to 96 percent (Ralf Topper, Colorado Geological Survey, 

written commun., 2007). Commercial and industrial water 

use that is not served by public water suppliers in the study 

area is small in relation to these other uses: 1.1 Mgal in the 

Merriland River watershed, 0.7 Mgal in the Mousam River 

watershed area, and 0.5 Mgal in the Branch Brook watershed. 

The remaining agricultural usage that relies on groundwater 

in the study area is even smaller, less than 0.3 Mgal across the 

study area (table 9). In all, the study identified 599.6 Mgal/yr 

in surface-water withdrawals (2.54 ft3/s) and 730.3 Mgal/yr in 

groundwater withdrawals (3.09 ft3/s).

The Sanford Sewerage District operates a municipal 

wastewater-treatment facility near the Mousam River in the 

City of Sanford. This facility treats wastewater from the City 

of Sanford, including residential, commercial, and industrial water users in the northwestern section of the study 

area, including the area around the Sanford withdrawal well. 

Wastewater discharges for the Sanford Sewerage District 

averaged 660 Mgal/yr (or 1.8 Mgal/d, 2.8 ft3/s) from 2009 
24 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

Table 9. Estimated withdrawals from groundwater and surface water, 2010, for the area in and around the Branch Brook watershed in 

southern Maine by water use category.

[Mgal/yr, million gallons per year; R., River; Rd., Road; --, none]

Name or sub-category

Number of 

houses not 

on public 

supply

Estimated 

number of 

persons

Surface-water withdrawals, 

Mgal/yr

Groundwater withdrawals, 

Mgal/yr

Merriland 

River

Branch 

Brook

Mousam 

River

Merriland 

River

Branch 

Brook

Mousam 

River

Domestic and public water-supply withdrawals

Domestic water use from private wells (estimated)

Mousam R. 629 1,467 -- -- -- -- -- 32.1

Branch Brook 488 1,123 -- -- -- -- 24.6 --

Merriland R. 634 1,472 -- -- -- 32.2 -- --

Public water supply withdrawals (reported values for 2010)

Mobile home park “A” 1 -- -- -- -- -- 8.1

Mobile home park “B” 1 -- -- -- -- -- 3.3

Merriland well2 -- -- -- 384.3 -- --

Harriseckett and Plant wells2 -- -- -- -- 32.2 --

Branch Brook withdrawals2 -- 590.5 -- -- -- --

Mobile home park “C” 1 -- -- -- 4.7 -- --

Mobile home park “D” 1 -- -- -- 6.1 -- --

Sanford well3 -- -- -- -- -- 220.1

Subtotals, domestic and public water supply -- 590.5 -- 427.4 56.8 263.6

Commercial and industrial withdrawals (estimated)

Schools (very small) -- -- -- 0.085 -- --

Very small restaurant (<13 employees) -- -- -- 0.12 -- --

Small restaurants (13–17 employees) -- -- -- 0.26 -- --

Amusement facilities (small) -- -- -- 0.067 -- --

Special trade contractors, unclassified -- -- -- 0.30 -- --

Computer integrated systems design -- -- -- 0.29 -- --

Saw and planing mills -- -- -- -- -- 0.63

Nondurable goods, unclassified -- -- -- -- -- 0.08

Excavating and grading work -- -- -- -- 0.28 --

Hotel/motel (very small or seasonal) -- -- -- -- 0.21 --

Subtotals, commercial/industrial -- -- -- 1.12 0.49 0.71

Agricultural withdrawals (estimated)

Irrigated cropland 3.1 -- 6.0 -- .09 --

Livestock -- -- -- -- -- .02

Fish hatcheries -- -- -- -- .12 --

Subtotals, agriculture 3.1 -- 6.0 .21 .02

Total estimated withdrawals, all categories

Total withdrawals, all categories 3.1 590.5 6.0 428.5 57.5 264.3

Total withdrawals in cubic feet per second (ft3/s) 0.013 2.63 0.025 1.82 0.24 1.12

1

Maine Drinking Water Program, written commun., 2012. Names withheld for protection of sensitive infrastructure.

2

Scott D. Minor, written commun., 2013.

3

Sanford Water District, written commun., 2013.
Simulation of Groundwater Flow and Discharge to Streams 25

through 2012. The Kennebunk Sewer Department operates a 

wastewater-treatment facility that discharges to the Mousam 

River approximately 2.75 mi upstream from the mouth of the 

Mousam River. Wastewater discharges for the Kennebunk 

Sewer Department averaged 290 Mgal/yr (0.8 Mgal/d, or 

1.2 ft3/s) from 2008 through 2011.

Approximately 6 mi2 of the study area is served by 

public water districts, and approximately 4.6 mi2 of the 

study area is served by public sewer systems. Wastewater 

from the unsewered areas that receive water supply from 

water districts returns to the groundwater system through 

domestic wastewater systems. The housing density within 

most of the approximately 1.4 mi2 that returns wastewater to 

the groundwater system is generally low- to medium-density 

residential. Septic system return-flow rates for low- and 

medium-density residential areas could be on the order of 

1.2 to 4.8 in/yr (DeSimone, 2004), or 0.08 to 0.3 Mgal/d, for 

the 1.4 mi2 area.

Simulation of Groundwater Flow and 

Discharge to Streams

The groundwater modeling component of the study was 

used to further develop the conceptual model of groundwater 

flow and the interaction of groundwater with streamflow in the 

study area. A steady-state groundwater model of the study area 

was constructed using the three-dimensional, finite-difference 

groundwater flow modeling code, MODFLOW–2005 

(Harbaugh, 2005). This model was used to simulate flow in the 

unconsolidated glacial deposits and shallow bedrock units.

Conceptual Model of the Groundwater Flow 

System

As described in the earlier section on groundwater flow, 

groundwater flow in the study area occurs primarily in the 

sand and gravel deposits overlying either bedrock or the finegrained silt/clay sediments of the Presumpscot Formation, 

with the exception of the coarse-grained sand and gravel body 

under the coastal plain area, which is stratigraphically below 

the Presumpscot Formation. Thin deposits of till overlying 

the bedrock are not significant water-bearing deposits in the 

study area, although in some areas where till is at the land 

surface it is thick enough to provide water to shallow dug 

wells. Groundwater is recharged locally and discharges to the 

Mousam River, Merriland River, Branch Brook, water-supply 

wells, and the ocean. 

Steady-State Numerical Groundwater Flow 

Model

The unconsolidated materials and shallow bedrock 

contained within an area defined by the watersheds of the 

Merriland River and Branch Brook plus adjacent parts of the 

Mousam River watershed were included in the groundwater 

flow model area shown in figure 10.

The groundwater system is represented by a 7-layer 

steady-state model (fig. 11); there were insufficient long-term 

groundwater level data available for a transient model of the 

whole study area. The bottom two layers represent the upper 

zone of the bedrock units, which were included in the model 

to investigate the potential amount of interaction between 

groundwater in the unconsolidated units and bedrock and to 

provide numerical stability for the model overall. The upper 

five layers represent the unconsolidated glacial materials and, 

in areas where the glacial material is thin, the upper zone of 

the bedrock aquifer.

The model was calibrated using available water-level data 

collected between June 21 and 29, 2012, which are considered 

a reasonable representation of the long-term average water 

levels (see earlier section on groundwater levels), and estimates of the long-term average base flows in the local rivers 

and streams.

Parameter estimation (also referred to as optimization) 

was used in the calibration phase. Model variables such as 

recharge, streambed conductance, and hydraulic conductivities 

were set up as parameters in the model. Head and streamflow 

measurements were set up as the calibration targets or 

observations. Insensitive parameters and others that could not 

be estimated were set and adjusted by hand using a trial and 

error process.

Spatial Discretization of the Model

The model area was discretized into a grid of 443 rows 

and 214 columns of cells with a uniform 150-ft spacing. The 

grid was rotated to the northeast at an angle of 23 degrees 

to coincide with the major axis of the deltaic deposits that 

compose the study area aquifers. Areas of the grid outside 

the modeled watersheds were inactive (fig. 10). The top of 

layer 1, the uppermost layer, is set equal to the land surface, 

which was interpolated from a lidar-derived digital elevation 

model in the eastern two-thirds of the model area, and 

from a standard 10-meter digital elevation model (DEM) 

derived from topographic maps in the town of Sanford (U.S. 

Geological Survey 1/3- and 1/9-arc second topographic data 

from the National Elevation Dataset at http://nationalmap.gov/

elevation.html). The upper two layers are both convertible 

between confined and unconfined, depending on the vertical 

position of the water table. The bottom of layer 2 is either 

25 ft below land surface or at the top of the silt-clay of 

the Presumpscot Formation, whichever is deeper (fig. 11). 

The composition of layers 1 and 2 varies spatially with the 

geology and includes the upper sandy aquifer materials, till, or 

bedrock, depending on the geology (fig. 11). Where the water 

table is below 17.5 ft from the land surface, layer 1 is inactive. 

If layer 1 is dry (inactive), layer 2 is unconfined.

The lower five layers of the model are simulated under 

confined conditions. Layers 3 through 5 consist of the 
26 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

k

k

kk

k

k

k

k

0

442

214

80

60

20

40

440

380

120

140

220

240

100

160

200

180

420

340

320

300

400

360

280

260

80

180

140

340

260

400

200

240

420

200

0

140

0

80

280

60

140

20

360

120

160

40

220

40

20

160

20

100

60

320

40

20

120

80

160

100

180

440

380

100

120

140

200

60

180

300

EXPLANATION

Recharge rates, 

in inches

less than 1.0

1.0 to 2.50

2.6 to 3.5

3.6 to 5.0

5.1 to 6.0

6.1 to 15.0

15.1 to 18.0

18.1 to 29.0

29.1 to 32.0

Model RIV cells

Model DRN cells

Boundary conditions

Constant head

Head-dependent flux

No flow

180 Model rows and columns

Production well, pumping rate in gallons per minute

6 to 20

21 to 500

501 to 1000

0 10.5 2 3 4 KILOMETERS

0 0.5 1 2 3 4 MILES

Figure 10. Model grid and boundary conditions for the numerical groundwater flow model of the area in and around the Branch Brook 

watershed in southern Maine.
Simulation of Groundwater Flow and Discharge to Streams 27

Layer 2

C'

C FEET

5025

NAVD 88

-25-50-75

-100-125-150

Distance, in feet

14,000 13,000 12,000 11,000 10,000 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 0

Layer 1

Layer 3

Layer 4

Layer 5

Layer 6 Layer 7

DATUM IS NAVD 88. VERTICAL SCALE GREATLY EXAGGERATED

225200175150125100

755025

NAVD 88

-25

FEET

Distance, in feet

28,000 26,000 24,000 22,000 20,000 18,000 16,000 14,000 12,000 10,000 8,000 6,000 4,000 2,000

B

0

B'

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Layer 6 Layer 7

DATUM IS NAVD 88. VERTICAL SCALE GREATLY EXAGGERATED

EXPLANATION

Bedrock

Buried gravel aquifer and ice-contact deposits 

Lithologic representation of model layers:

Presumpscot Formation

Glacial till

Alluvium

Stratified sand and gravel

Elevation, in feet Elevation, in feet

Figure 11. Representation of model layers for cross-sections 

B–

B’ and 

C–

C’ in the area in and around the Branch Brook watershed in southern Maine.
28 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

remainder of the unconsolidated surficial materials or shallow bedrock where the surficial materials are less than 25 ft 

thick (fig. 11). Where the Presumpscot Formation is present, 

it is represented in layers 3 through 5. Figure 11 shows the 

vertical layering of the model across two of the cross sections 

illustrated in figure 3. Cross section B–B′ crosses the model 

at approximately model column 210, and cross section C–C′

crosses the model at model column 366. The bottom of layer 5 

is the bedrock surface where the bedrock surface is more than 

45 ft below land surface or at 45 ft if the surficial units are less 

than 45 ft thick. Layers 6 and 7 represent 300 ft of bedrock, 

with layer 6 representing the top 30 ft of this thickness and 

layer 7 the remainder.

Boundary Conditions

The extent of the groundwater model area is defined 

as much as possible by inferred groundwater divides (as 

determined by topographic divides) around the study area, 

using the bedrock highs of the Merriland River watershed as 

the southern model edge. The topographic divides are treated 

as no-flow boundaries, with exceptions as outlined below. The 

northern model edge is defined by the Mousam River, which 

is incised into the silt and clay of the Presumpscot Formation 

along much of its length, which would prevent any appreciable 

groundwater movement under the river. The Mousam River 

is modeled as a no-flow boundary. The primary concern of 

the model on the western edge is in the headwaters of the 

Merriland River and Branch Brook, but as there is no clear 

groundwater divide to use in this area, the model boundary 

was moved inland to include more of the Mousam River 

watershed so that there would be few (if any) effects of the 

boundary on the model area of interest.

As shown in figure 1, the watershed boundaries defining the western and southern edge of the area included in the 

active model area fall across small sections of mapped sand 

and gravel aquifer. These were defined in the model as headdependent boundaries (general head boundaries) to account for 

small amounts of groundwater flow and to reduce any boundary effects they might cause (fig. 10). These general head 

boundaries (GHBs) are active from the land surface to the 

bottom of the surficial sand and gravel aquifers. Additionally, 

as the possible extent of the buried sand and gravel aquifer 

under the coastal plain became evident, GHBs were added in 

layers 3 through 5 crossing the model boundary south of the 

Merriland River and across the Mousam River to allow for 

inflow to the model from buried sand and gravel outside the 

model boundaries.

Discharge to rivers and streams was simulated using the 

Drain (DRN) and River (RIV) packages (Harbaugh, 2005) in 

MODFLOW. Small streams were simulated using the DRN 

package (fig. 10), where stream discharge is modeled as a 

head-dependent flow across the stream bottom, which is onedirectional and no water transfer occurs if the simulated head 

in the aquifer drops below the defined elevation of the stream 

bottom. As described in the earlier section on groundwater 

flow, springs are particularly common along some of the short, 

steep tributaries to Branch Brook, and also to tributaries to 

the Mousam River. Individual springs were not mapped for 

the study, being very numerous (Charles Fitz, University 

of Southern Maine, written commun., 2011). Discharge 

from stream segments containing springs was handled with 

a separate leakance value from the other stream segments, 

although they were both simulated using the DRN package. 

Larger rivers, including the Mousam River, the main stem 

of Branch Brook, and the downstream part of the Merriland 

River (fig. 10), were simulated in the model using the RIV 

package, in which flux can move in either direction between 

the aquifer and the river bottom, depending on the head in the 

aquifer and the river stage.

The ocean is modeled as a constant head boundary. The 

elevation of the top of the cells that are ocean is derived from 

the digital elevation model used for the study area. Cells 

below layer 1 are treated with an equivalent freshwater head 

approach, in which the constant head is increased as the depth 

of the cell center increases such that the head is equal to 

1 + 0.025*depth.

Stresses

The stresses applied to the groundwater system in the 

model include recharge and pumping. Evapotranspiration 

was not modeled explicitly but is included implicitly in the 

recharge stress.

Recharge was applied as a constant flux to the top active 

cell in the model. The spatial variation in recharge rates 

(fig. 10) was based on a combination of soil drainage classes 

and surficial geologic units. Recharge rates were treated as 

model parameters during the optimization phase of model 

calibration and were adjusted within a range of reasonable 

values, which were determined on the basis of previous studies 

and a review of the literature for other recharge rates used in 

New England groundwater studies. Some of the recharge rates 

used in the calibrated model are quite high compared to other 

New England groundwater studies. The high measured base 

flows in the streams in the study area (Branch Brook, Cold 

Water Brook, and Perkins Marsh Brook in particular) largely 

determined the need for high recharge rates in the coarsegrained deposits in the central and western parts of the study 

area. Previous groundwater modeling efforts in the study area 

(Robert Gerber, oral commun., 2012) also required unusually 

high recharge rates, which corroborates this finding. The 

recharge rates used in the calibrated model are between 5 and 

63 percent of total precipitation. A few areas within the sandy 

part of the central Branch Brook watershed have very sparse 

vegetation, which limits the evapotranspiration potential of 

these areas substantially. The recharge rates in those areas 

were increased to 70 percent of total precipitation.

Because of the small extent of the unsewered residential 

areas receiving public water supply (approximately 2.7 percent 

of the study area), the model does not explicitly account for 

the potential increase in recharge from domestic septic return 
Simulation of Groundwater Flow and Discharge to Streams 29

flow. As most of the private well septic discharge percolates 

back into the local groundwater system from which it was 

withdrawn, recharge rates were not altered in the rural residential areas either.

Pumping from the eight water-supply wells in the study 

area was simulated using the WEL package (Harbaugh, 2005). 

Pumping for each well location was divided equally between 

model layers, depending on the screened intervals of the 

pumping wells. Pumping rates for the four small water-supply 

wells (table 10) were based on reported withdrawals on file 

with the Maine Drinking Water Program (Andrews Tolman, 

written commun., 2010) and were between 3 and 8 gallons 

per minute (gal/min). These wells were assumed to pump year 

round. Pumping from the larger municipal pumping wells 

(table 10) was based on reported pumping rates and data from 

the water utilities (Scott D. Minor, Assistant Superintendent, 

Kennebunk, Kennebunkport and Wells Water District, 

written commun., May 2014; David Parent, Superintendent, 

Sanford Water District, written commun., September 2013). 

The Sanford well pumps continuously at about 400 to 

450 gal/min. The Harriseckett, Plant, and Merriland River 

wells pump at rates of 150, 350, and 1,000 gal/min but only 

during the summer months. The pumping rates used in the 

model for these wells (table 10) were based on how long they 

had been pumping at the time of the water-level survey in 

June 2012. The Merriland River well was simulated using the 

full 1,000 gal/min pumping rate (192,000 ft3/d), as it had been 

pumping for several months at the time of the survey. Lacking 

data to indicate how long the Plant and Herriseckett wells 

take to reach steady state with respect to streamflow depletion 

in the local rivers, these two wells were assigned withdrawal 

rates in the model that were 70 to 75 percent of their full 

pumping rates, as they had been turned on within less than a 

month of the water-level survey.

Hydraulic Properties

Hydraulic properties used in the model included 

streambed and riverbed hydraulic conductivity, horizontal 

hydraulic conductivity in the hydrogeologic units, anisotropy, 

and vertical hydraulic conductivity. These hydraulic properties 

were represented as parameters and adjusted during the model 

calibration and parameter estimation within reasonable limits 

determined by previous investigations and literature surveys. 

The parameter zones were distributed primarily on the basis 

of the surficial and bedrock geology and were adjusted and 

simplified somewhat during calibration. The unconsolidated 

deposits were simulated using 12 parameter zones representing 

11 hydrogeologic units (table 11). These include the nine 

geologic units shown in figure 2 plus a zone representing 

the buried gravel aquifer (in layers 4 and 5; see figs. 3 and 

11, cross section C–C′) under the coastal plain, a zone 

representing surface-water bodies, and a multiplier zone used 

for the Presumpscot Formation areas. As described earlier, the 

Presumpscot Formation is simulated in layers 3 through 5 of 

the model. However, the transition from coarse sandy material 

in the western part of the model to the silt and clay of this 

unit is not abrupt, but occurs gradually. Therefore, a dataset 

representing this spatially graded hydraulic conductivity 

distribution was used to represent the Presumpscot Formation 

and horizontally equivalent unconsolidated deposits in the 

model (layers 3 through 5). The hydraulic conductivity of this 

zone ranges from 50 ft/d in the Sanford area to 0.02 ft/d in 

the Mousam River/Branch Brook area. The multiplier zone 

was used to adjust the values in this zone up or down during 

parameter estimation. The vertical anisotropy for the surficial 

hydraulic conductivity units ranged from 1:10 to 1:200 in the 

final model. The high degree of anisotropy needed for the 

model reflects the vertically heterogeneous nature of many 

of the deposits and the fact that lenses of silt and clay can be 

found in many of the coarse-grained units.

Model areas used to simulate surface-water bodies 

(ponds, reservoirs, the Atlantic Ocean; fig. 1) were assigned 

hydraulic conductivity values of 5,000 ft/d. Using a very high 

value for hydraulic conductivities in these areas effectively 

simulates the lack of resistance to water flow and allows 

the elevation of the water body to be simulated rather than 

proscribed.

The bedrock is represented by five hydraulic conductivity 

zones, which range from 8 × 10-4 to 0.35 ft/d (table 11). The 

uppermost part of the bedrock is reported to be more fractured than the deeper zones (Randall and others, 1988) and is 

therefore represented with a slightly higher hydraulic conductivity than much of the rest of the bedrock areas. The vertical 

anisotropy in the bedrock units ranges from 1:1 to 1:10.

Streambed and riverbed conductivities were determined 

by calibration, within reasonable ranges determined from the 

literature. The riverbed conductivities used in the RIV package ranged from 0.1 ft/d in the Merriland River to 1.5 ft/d in 

Branch Brook. Streams and seeps simulated with the DRN 

package had streambed conductance values of 1.44 and 

0.57 ft/d (table 12).

Model Calibration Using Parameter Estimation 

and Observations

Methods outlined in Hill and Tiedeman (2007) were 

followed during calibration using the UCODE_2005 software 

package (Poeter and others, 2008). These methods allow for 

the explicit accounting for uncertainty in the water levels 

and streamflows used as calibration targets, documenting the 

model sensitivity to model variables (parameters) and sensitivity to data used in the model.

Statistics on the fit of the model to the observed values 

(the ability of the model to reproduce the observations) are 

used as the dependent variables in the parameter estimation, whereas the model parameters are set up as independent 

variables through a series of linear and nonlinear regression 

calculations. The optimization of the parameter values is done 

using an iterative process, during which the output of each 

model iteration is used to determine parameters that can be 
30 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

Table 10. Pumping wells simulated in the groundwater flow model of the area in and around the Branch Brook watershed in southern 

Maine.

[fig., figure; ft, feet; gal/min, gallons per minute; ft3/d, cubic feet per day; R., River; yr, year; approx., approximately]

Well name Map number 

(fig. 1) Watershed Depth, in ft

Model 

layers Pumping regime Pumping rate, gal/min

Pumping rate 

in model 

(ft3/d)

Sanford well 1 Mousam R. 65 4 365 days/yr 400–450 86,624

Mobile home park “C” well 4 Merriland R. 10 1 365 days/yr 4.5* 1,728

Mobile home park “A” well 2 Mousam R. 64 4, 5, 6 365 days/yr 7.4* 2,972

Mobile home park “D” well 5 Merriland R. 15 1 365 days/yr 5.6* 2,246

Harriseckett well 7 Branch Brook 45 3, 4 Approx. 34 days/yr 150 20,000

Mobile home park “B” well 3 Mousam R. 264 3, 4, 5 365 days/yr 3.0* 1,210

Merriland River well 8 Merriland R. 128 4, 5 6 months/yr 1,000 192,000

Plant well 6 Branch Brook 56 3, 4 Approx. 53 days/yr 350 50,000

*

Reported to the State as an annual total volume; rate shown assumes constant (24 hours/day) pumping.

Table 11. Hydrogeologic units and corresponding hydraulic properties.

[ft/d, feet per day; Fm., Formation; NA, not applicable]

Unit Parameter name Composite scaled 

sensitivity Estimated? Calibrated value (ft/d)

Vertical 

anisotropy

Hydraulic properties for unconsolidated units

Holocene alluvium HK_Alluvium 1.3 Yes 1.97 1/100

Nearshore marine deposits HK_MrnSand 2.7 Yes 3.56 1/100

Undifferentiated marine deposits HK_PmUndiff 0.95 Yes 1.49 1/100

Presumpscot Fm. (in layers 1–2) HK_Presump 1.9 Yes 0.19 1/100

Ice-frontal delta deposits HK_Delta1 0.54 Yes 27.9 1/50

Distal delta deposits HK_Delta2 5.5 Yes 6.30 1/100

Glacial till HK_Till 0.98 Yes 0.79 1/10

Modern wetlands HK_Wetland 0.003 No 40 1/10

Buried gravel aquifer in coastal plain HK_BuriedGrav 2.78 Yes 140 1/200

Coarse-grained distal delta deposits HK_Coarse 0.7 Yes 41.2 1/10

Multiplier zone for layers 3–5 HK_ClayEXP 1.66 Yes 1.81 NA

Hydraulic properties for bedrock units

Granite bedrock HK_Granite 0.29 No 0.1 1/1

Shallow bedrock of all types HK_L1ROCK 1.0 Yes 1.09 1/10

Metamorphic bedrock HK_MMRock 0.20 No 0.01 1/1

Shear zone (fault) bedrock HK_ShearZn 0.04 No 0.5 1/1

Very tight granite bedrock HK_Special 1.0 No 0.008 1/10
Simulation of Groundwater Flow and Discharge to Streams 31

Table 12. Riverbed and streambed hydraulic properties.

[ft/d/ft, feet per day per foot; RIV, MODFLOW-2005 RIVER package; 

DRN, MODFLOW-2005 DRAIN package]

Unit

Composite 

scaled 

sensitivity

Estimated?

Calibrated 

value

(ft/d/ft)

Conductance for RIV cells

KRIV_BranchBrook 0.20 No 1.5

KRIV_Merriland 0.24 No 0.1

KRIV_Mousam 0.02 No 1.0

Conductance for DRN cells

KDR_Seeps 5.0 Yes 0.57

KDR_Streams 0.79 Yes 1.44

estimated and if trial-and-error changes to other parameters 

or changes to the conceptual model are needed. During the 

optimization process, the sensitivity of the model to each 

parameter value is determined for each optimization iteration, 

and only parameters that exceed a threshold sensitivity (and 

are not highly correlated with each other) are estimated (see 

Hill and Tiedeman [2007] for further details on the process of 

parameter estimation).

Observations

Observations used to calibrate the groundwater model 

included head observations and flux observations. Observations were assigned weights used in the model sensitivity and 

parameter estimation analysis. The head (groundwater level) 

observations consisted of the water levels measured during the synoptic groundwater level survey in June 2012 plus 

15 surface-water elevation points (these were a mixture of 

wetlands, reservoirs, and ponds; fig. 6). The flux observations 

consisted of groundwater discharge (base flow) to streams and 

rivers in the model area.

Groundwater Level Observations

Head observations used in the calibration consist of the 

groundwater level measurements collected in 2012 (listed in 

appendix 1), and the locations are shown in figure 6. Every 

layer in the model had at least one head observation. There 

were a total of 151 groundwater level observations used in 

calibrating the model. Many of these were concentrated in 

several clusters of monitoring wells installed for previous 

investigations or for routine monitoring in association with the 

groundwater withdrawal wells in the study area. The homeowner wells and surface-water points were used to fill in the 

other areas of the model where monitoring wells did not exist. 

Although almost one-half of the total observations were shallow wells or surface-water observations in layer 1 (72 points), 

the distribution of wells in layers 2 through 7 was fairly even, 

and 52 of the wells were 50 or more feet deep (table 13).

Table 13. Summary of groundwater level observation points 

used in calibrating the groundwater flow model of the area in and 

around the Branch Brook watershed in southern Maine.

[<, less than; ft, feet; ≥, greater than or equal to]

Observation information Number of 

observations

Total number of groundwater level observations 151

Wells 136

Surface-water points 15

Sand and gravel wells 117

Till wells 8

Bedrock wells 11

Wells <50 ft deep 83

Wells ≥50 ft deep 52

Observations in layer 1 72

Observations in layer 2 18

Observations in layer 3 10

Observations in layer 4 17

Observations in layer 5 13

Observations in layer 6 11

Observations in layer 7 10

The variances used to calculate weights for the observations for water levels in wells (appendix 1) included a combination of measurement and elevation errors. Most of the 

water levels were assigned a measurement error of plus or 

minus 1 ft, which accounted for the changes in water levels 

in the aquifer during the several days that the water-level 

survey took place. Some of the monitoring well elevations 

were determined using global positioning system (GPS) 

technology or surveying, and these were assigned an elevation error of ±0.1 ft. The other elevations were derived from a 

digital elevation model of the area. Much of the study area has 

lidar surface elevation data, and wells in the lidar area were 

assigned an elevation accuracy of ±1 ft. Wells in the rest of 

the study area were assigned an elevation accuracy of ±5 ft. 

The surface-water elevation points were assigned an accuracy equal to the appropriate land-surface elevation accuracy, 

depending on the location. The variances derived from these 

errors were summed to calculate the weights on each observation. Additional details on the use of observations and weighting are described in Hill and Tiedeman (2007).

Streamflow Observations

Because the groundwater model was developed to 

represent a long-term average condition for the early summer 

time period, the streamflow observations to use as calibration 

targets represented base-flow conditions from June through 

July. Base flows (groundwater discharge) are used in the 

model because the model cannot simulate direct runoff and 
32 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

because base flow is a conservative target for streamflow, as 

flows are lower than whenever there is runoff. The method 

used to calculate base-flow values was similar to that used 

for calculating the monthly mean flows for Branch Brook and 

the Merriland River using the MOVE.1 technique described 

earlier in the section on surface-water resources, but the 

method was applied to all 13 of the streamflow measurement 

sites in the study area. The index flows in this case were base 

flows for the Mousam River, Bearcamp River, and Branch 

Brook gages (stations 01069500, 01064801, and 01069700) 

during June and July from 2008 through 2012 time period. 

The PART program (Rutledge, 1998) was used to analyze the 

hydrographs for these dates to determine average base flows 

for these months. These base flows were averaged to obtain an 

index site flow, from which the base-flow observations at each 

site were calculated (table 14). For context, the base-flow calibration target for Branch Brook at the continuous streamgage 

(BB#2, station 01069700) is shown in figure 12 with the daily 

flows during late June when the groundwater observation data 

were collected. The base flow calculated as the model calibration target (17.2 ft3

/s) is close to the daily streamflow at the 

end of June 2012, as the streamflows were declining during 

the groundwater survey. This indicates that the base-flow 

calibration targets used in the model are a reasonable representation of base flows to use with the groundwater measurements 

collected in 2012.

After the base flow was calculated for each surface-water 

site, the base flows were divided into incremental flows for 

the streamflow reach just above each site. This was done by 

subtracting the base flow at the site immediately upstream 

from the base-flow total at that site, if there was an upstream 

site. This applied just to the observation sites on Branch Brook 

and the Merriland River.

In the model, the base-flow values, from here on referred 

to as “base-flow observations” are calculated as the sum of 

the RIV and DRN drain cells in the watersheds of each of the 

streamflow measurement sites (fig. 13). Because the model 

simulates groundwater discharge from both RIV and DRN 

cells, the observed base-flow amounts in each subwatershed 

had to be partitioned between RIV cells and DRN cells for the 

model calibration process. Furthermore, because the model 

simulates two types of DRN cells (seepage [spring] flow 

cells and stream cells, which are differentiated by streambed 

conductance), some of the observed base flows had to be 

further partitioned into two DRN observations (table 14). The 

percentages for partitioning the flows were made on the basis 

of professional judgment, using the number of RIV and DRN 

cells in each subwatershed as a guide.

The base-flow observations were assigned uncertainty 

values to use in the model calibration and against which to 

evaluate the simulated streamflow values from the calibrated 

model. For the parameter estimation and sensitivity analysis, 

the uncertainty values were expressed as a standard deviation. 

For each of the base-flow observations, before apportioning them between RIV and DRN observations, the standard 

deviation was estimated, which is needed for the calculation 

weights for parameter estimation. The standard deviation for 

each subwatershed (table 14) was estimated using the streamflow measurements made in the field at each site. The separating of the observed flow into the RIV and DRN individual 

observations required doubling the total standard deviation in 

the observations because the actual division of flow between 

the two types of discharge cells was unknown. The standard 

deviations for each partitioned observation used during the 

model calibration are shown in table 14. The weight of each 

observation is the inverse of the coefficient of variation, which 

is the square of the standard deviation. Additional details on 

the use of observations and weighting are described in Hill 

and Tiedeman (2007).

Parameters

As stated earlier, the model was calibrated using a 

combination of parameter estimation and trial-and-error 

adjustments in the model variables. A “reasonable range” of 

values for each parameter is input to the process (determined 

using values from the literature and previous studies [tables 2 

and 3]) for comparison with the value output by the parameter 

estimation routine. Generally, parameters with composite 

scaled sensitivities greater than 0.5 can be estimated (Hill and 

Tiedeman, 2007), as long as they are not highly correlated 

with other estimated parameters. Of the 31 parameters set 

up for the model, 18 were sensitive enough to estimate. Two 

of these were not estimated because the estimation arrived 

at values outside their reasonable ranges (RCH_Sandy1 and 

RCH_Till). One (HK_Special) was not estimated because it 

was correlated with another parameter (RCH_Bedrock). Of 

the final 15 determined by use of parameter estimation, there 

were 2 recharge parameters, 11 horizontal K parameters, and 

2 streambed K parameters (table 15). As the model variables 

were adjusted and tested for model fit, alternatives to the 

original conceptual model also were tested to determine if 

they helped in providing a better model fit. Some adjustments 

to the original assumptions of the distribution of the geologic 

units at depth were made in the model to improve the model fit 

as necessary.

Model Fit to Observations

The overall model fit is assessed by evaluating 

observations and their simulated equivalents. The modelsimulated water levels for the head observations at 134 wells 

and 15 surface-water points are graphed against the observed 

values in figure 14 (one well was simulated as dry and 

could not be plotted). The correlation between observed and 

simulated heads indicated a very good agreement (R2

=0.99). 

The weighted residuals (residuals are the observed values 

minus the simulated values) plotted against the unweighted 

simulated heads also indicate a slight negative bias in the 

weighted residuals (fig. 15). The mean difference between the 

observed and simulated heads (observed minus simulated) is 
Simulation of Groundwater Flow and Discharge to Streams 33

Table 14. Streamflow observations used in calibrating the Branch Brook area groundwater flow model.

[USGS, U.S. Geological Survey; ID, identification; ft3/s, cubic feet per second; ft3/d, cubic feet per day; BB, Branch Brook; --, not applicable]

USGS 

station 

number

Local ID

Name of 

partitioned 

observations

Total flow 

this site, 

ft3/s

Incremental 

(subwatershed) 

observed flow, 

ft3/s

Incremental 

(subwatershed) 

observed flow, 

ft3/d

Standard 

deviation on 

incremental 

flow, 

ft3/d

Standard 

deviation on 

partitioned 

flow, 

ft3/d

Observation 

flux, 

ft3/d

01069640 BB #7 BB7_Str 0.77 0.77 66,328 15,805 -- 66,328

01069645 BB #6 BB6_Str 0.92 0.15 12,869 5,268 -- 12,869

01069660 BB #5 5.42 4.50 388,721 52,683 -- --

BB5_Riv -- -- -- -- 31,113 207,462

BB5_Seeps -- -- -- -- 47,912 181,259

01069680 BB #4 0.63 0.63 54,057 18,439 -- --

BB4_Seeps -- -- -- -- 9,167 13,908

BB4_Str -- -- -- -- 18,492 40,149

01069690 BB #3 13.11 7.07 610,456 26,341 -- --

BB3_Seeps -- -- -- -- 31,363 502,337

BB3_Riv -- -- -- -- 8,149 108,118

01069700 BB#2 17.04 3.93 339,824 52,683 -- --

BB2_Seeps -- -- -- -- 16,486 110,612

BB2_Str -- -- -- -- 11,588 86,968

BB2_Riv -- -- -- -- 50,951 142,245

01069720 BB #1 18.13 1.06 91,326 13,171 -- --

BB1_Seeps -- -- -- -- 6,703 48,302

BB1_Riv -- -- -- -- 13,053 43,024

01069505 Perkins Marsh Perkins_Str 2.73 2.73 235,498 18,439 -- 235,498

01069515 Cold Water Cold_Seeps 2.11 2.11 182,156 13,171 -- 182,156

01069580 Day Brook 2.13 2.13 183,823 26,341 -- --

Day_Seeps -- -- -- -- 3,216 2,259

Day_Str -- -- -- -- 36,296 181,564

01069725 BB# 8 BB8_Str 0.83 0.83 72,021 26,341 -- 72,021

01069785 Merri #1 9.31 0.76 65,765 26,341 -- --

Merri1_Str -- -- -- -- 13,829 30,203

Merri1_Riv -- -- -- -- 25,683 35,562

01069780 Merri #2 8.55 8.55 739,022 52,683 -- --

Merri2_Str -- -- -- -- 74,701 722,188

Merri2_Riv -- -- -- -- 4,323 16,834
34 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

1

10

100

1,000

June 1 June 11 June 21 July 1 July 11 July 21 July 31

Streamflow, in cubic feet per second

Date

June and July 2012

Minimum

25th 

50th 

75th 

Maximum

Base-flow calibration 

target for station 01069700

(17.2 cubic feet per second)

EXPLANATION

Percentiles for the 

period of record (2008−13)

Period of groundwater data

collection (June 26−29, 2012)

Figure 12. Percentiles of daily streamflow in Branch Brook at station 01069700 for June and July for the period of record, June and 

July daily streamflows for 2012, and the base-flow calibration target for the groundwater flow model, southern Maine.

1.4 ft, and the mean absolute difference between the observed 

and simulated heads is 4.0 ft. Given that the range in observed 

heads for the model area is 282 ft, these errors represent 

0.5 and 1.4 percent, respectively, of the total head change 

across the model. The surface-water points fall very close to 

the line of equality (fig. 14), whereas the till wells plot slightly 

above the line of equality, meaning that the simulated heads 

are slightly lower, on average, than observed. The bedrock 

wells have water levels that are somewhat over-predicted, 

especially in the 140- to 175-foot elevation range.

The spatial distribution of the head residuals (observed 

minus simulated heads) in figure 16 shows that the simulated heads in the areas underlain by till and shallow bedrock 

(between the coastal plain area and the central part of the 

study area) are higher than observed. Several of the heads in 

the Sanford area also are simulated somewhat higher than 

observed. The heads in the central part of the study area, in the 

Branch Brook watershed, show the lowest general residuals 

(both positive and negative) in the model area.

The discrepancy between observed and simulated heads 

is somewhat worse than average (5.7 ft mean absolute difference between observed and simulated heads) for the sand and 

gravel wells in the coastal plain section of the model, which 

are primarily in the vicinity of the pumping wells in that area 

(fig. 16). The head data in the vicinity of the pumping wells 

were difficult to fit for two reasons: (1) pumping was not 

steady and the observation points had not fully equilibrated 

to the pumping stresses when the water-level survey was 

conducted, and (2) many of the wells were in the buried gravel 

aquifer, which appears to have more heterogeneity than was 

possible to simulate in the model. This lack of fit is evident in 

the somewhat wide spread in the weighted residuals plot as 

well (fig. 15). 

The observed and simulated base flows in the reaches 

above the streamflow measurement sites are shown in 

figure 17. The fit of the base-flow data is very good, and 

most of the model-simulated flows fall well within the 

95-percent confidence intervals of the observations. The 

primary exceptions to this are for BB#3, for which the 

confidence interval is relatively narrow and which has a 

relatively small contributing watershed for the amount of 

flow that enters the river in this segment. The recharge rate 

in this contributing watershed is very high already, so there 

were limits to the amount of water that was available for 

discharge to Branch Brook. The Merriland #2 site is the other 

significant observation in which the model-simulated flows 

are somewhat lower than desired. The contributing watershed 

to this observation site is large, but consists largely of areas 

with till and shallow bedrock, which have low recharge rates. 

Increasing the recharge for these areas beyond what was 

considered a reasonable range was not a favorable option. 

The lack of fit with both of these observations may be a result 
Simulation of Groundwater Flow and Discharge to Streams 35

0

442

214

80

60

20

40

440

380

120

140

220

240

100

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BB#2

BB#1

BB#8

BB#3

BB#4

BB#7

BB#6 BB#5

Merri#2

Merri#1

Day Brook

Cold 

Water

Perkins 

Marsh

140 Model rows and columns

Streamflow observation sites

Active model boundary

Model RIV cells

Model DRN cells

BB#2 Base-flow observation zones

EXPLANATION

Merriland River

Branch Brook

Mousam River

Mousam River

0 10.5 2 3 4 KILOMETERS

0 0.5 1 2 3 4 MILES

Figure 13. Subwatersheds used as base-flow observation zones in the groundwater flow model of the area in and around the Branch 

Brook watershed in southern Maine.
36 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

Table 15. Parameters used in the groundwater flow model of 

the area in and around the Branch Brook watershed in southern 

Maine, with composite scaled sensitivities and calibrated values.

[RIV, MODFLOW-2005 RIVER package; DRN, MODFLOW-2005 DRAIN 

package; Calibrated values for conductances are in feet per day; calibrated 

values for recharge parameters are in inches, calibrated parameters for 

hydraulic conductivity are in feet per day]

Unit Composite 

scaled sensitivity Estimated? Calibrated value

Conductances for RIV cells

KRIV_BranchBrook 0.20 No 1.5

KRIV_Merriland 0.24 No 0.1

KRIV_Mousam 0.02 No 1.0

Conductances for DRN cells

KDR_Seeps 5.0 Yes 0.57

KDR_Streams 0.79 Yes 1.445

Recharge parameters

RCH_Alluv_Urb 0.17 No 5.0

RCH_Bedrock 1.2 No 2.3

RCH_Moraine 0.15 No 3

RCH_Sandy_1 15.0 No 29

RCH_Sandy_2 3.9 Yes 15.9

RCH_Till 1.36 Yes 5.0

RCH_Wetlands 0.002 No 2.5

RCH_Water 0.20 No 1.0

RCH_Xtra 0.47 No 3.0

Hydraulic conductivity parameters

HK_Alluvium 1.3 Yes 1.97

HK_MrnSand 2.7 Yes 3.56

HK_PmUndiff 0.95 Yes 1.5

HK_Presump 1.9 Yes 0.19

HK_Delta1 0.54 Yes 28

HK_Delta2 5.5 Yes 6.3

HK_Till 0.98 Yes 0.79

HK_Wetland 0.003 No 40

HK_BuriedGrav 2.78 Yes 69.8

HK_Coarse 0.7 Yes 41.2

HK_ClayEXP 1.66 Yes 1.81

HK_Granite 0.29 No 0.1

HK_L1ROCK 1.0 Yes 1.09

HK_MMRock 0.20 No 0.01

HK_ShearZn 0.04 No 0.5

HK_Special 1.0 No 0.008

of model error or the range in measurement error. Site BB#8 

also is under-simulated in the model, although this site is 

quite close to the Plant and Herriseckett pumping wells, and 

the wells were not pumping when many of the streamflow 

measurements used to determine the base-flow observation 

were made. The over-simulation of base flows for BB#6, 

which is in the headwater section of Branch Brook, is not 

considered significant because of the particularly small 

contributing area and the lack of detail in the input datasets in 

this area.

Simulated Groundwater Levels and Flow Under 

Steady-State Conditions

The simulated steady-state heads and groundwater flow 

directions in the calibrated model in model layers 1 and 4 are 

represented in figure 18. Heads range from 0 ft at the Atlantic 

Ocean to greater than 250 ft at the northwestern edge of the 

model in the Sanford area. In layer 1, the head contours generally follow the land surface and are most widely spaced where 

the hydraulic conductivities are highest. Breaks in the contours 

in the layer 1 map indicate areas where the model cells in layer 

1 are dry for this unconfined simulation. Flow directions are 

towards surface-water features. There is a very small amount 

of flow between the model and the general head boundaries in layer 1, which are shown on figure 18. In layer 4, the 

heads range from -10 ft in the vicinity of the largest pumping 

well near the ocean to 260 ft in bedrock hills in the northwest 

corner of the model. Although the heads and flow directions 

in layer 4 are quite similar to those in layer 1, there are some 

differences. The pumping wells, especially the larger ones, 

influence the water levels in layer 4 much more than in layer 

1, and cones of depression are developed in the Sanford area 

and near the pumping wells in the coastal plain. The highly 

conductive buried gravel aquifer in layer 4 and the pumping in 

that aquifer greatly influence the flow directions in layer 4 in 

that area. There is more groundwater flow crossing the general 

head boundaries in layer 4 than in layer 1, especially along the 

model edge where the gravel aquifer crosses to the south. The 

vertical head gradients are generally downwards from layer 1 

to layer 4 in most of the model area. The exceptions to that are 

in the major stream and river valleys, where groundwater flow 

is discharging to the surface-water features.

Model Sensitivity Analysis and Parameter 

Uncertainty

The parameter estimation process generates data describing the sensitivity between parameters and observations in 

the model. Dimensionless scaled sensitivities (DSS) indicate 

the sensitivity of each simulated observation to small changes 

in parameter values, whereas composite scaled sensitivities 

(CSS) indicate the composite sensitivity of all the observations 

to changes in each parameter value. The DSS values (listed in 

appendix 2) are generated for every parameter and observation 
Simulation of Groundwater Flow and Discharge to Streams 37

0

25

50

75

100

125

150

175

200

225

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275

0

-25

255075

100125150175200225250275

Observed head, in feet above NAVD 88

Simulated head, in feet above NAVD 88

EXPLANATION

Linear fit

Surface-water points

Bedrock wells

Till wells

Sand and gravel wells

Line of equality

-25

-50

-50

Figure 14. Relation between observed and model-simulated heads for the area in and around the Branch Brook watershed in 

southern Maine.

and can be used to examine which observations or groups of 

observations have the most influence on particular parameter 

estimates in the model. The CSS values, in contrast, reflect 

overall model sensitivity to each parameter. The model parameters with the greatest sensitivity overall include (with CSS 

values in parentheses) the RCH_Sandy1 (15.0), HK_Delta2 

(5.5), and KDR_Seeps (5.0) parameters (table 15).

The RCH_Sandy1 parameter was particularly influential 

on the streamflow observations but not the head observations. 

The HK_Delta2 and KDR_Seeps parameters primarily 

influenced heads in the central part of the Branch Brook 

watershed. Simulated heads in this area also were particularly 

sensitive to the HK_L1ROCK, HK_Alluv, and HK_Presump 

parameters. Together, these parameters control the supply of 

water to the sand and gravel aquifer and the rate at which the 

groundwater discharges to Branch Brook. The model in this 

area is quite sensitive to the vertical layering setup and how 

the model simulates discharge to the springs and seeps that 

feed Branch Brook.

In the coastal plain area, simulated heads were most 

sensitive to a range of parameters, including the RCH_Sandy1, 

HK_MrnSand, RCH_Sandy2, HK_BurGrav, and HK_ClayExp 

parameters. These parameters control the supply of water to 

this area, and the rate at which flow moves vertically from the 

surficial units, through the confining Presumpscot Formation, 

and into the buried gravel aquifer below, as well as the rate 

at which water in the buried gravel aquifer flows towards the 

Merriland River pumping well.

Simulated heads in the Sanford area were most sensitive to the HK_Delta2, HK_ClayExp, RCH_Sandy1, and 

RCH_Sandy2 parameters and were somewhat sensitive to the 

HK_Coarse and KDR_Stream parameters. This area was surprisingly insensitive to the KRIV_Mous parameter, especially 

how close many of the wells are to the river in that area. As 

the HK_ClayExp parameter controls the hydraulic conductivity of the sand and gravel surrounding the pumping well, 

sensitivity to that parameter is not surprising.
38 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

-25

-20

-15

-10

5

0

5

10

15

20

25

-50 0 50 100 150 200 250

Weighted residuals on simulated heads

Unweighted simulated head, in feet above NAVD 88

Figure 15. Weighted residuals and unweighted simulated values for heads in the groundwater flow model of the area in and 

around the Branch Brook watershed in southern Maine.

The simulated heads in the bedrock and till wells across 

the study area displayed a mixed degree of sensitivity to the 

model parameters. Only one bedrock well head simulation 

(ME_YW_888) was particularly sensitive to the RCH_

Bedrock parameter (the till well heads were much more 

sensitive to this parameter); in contrast, several of the bedrock 

wells had heads that were quite sensitive to the RCH_Till 

parameter. The simulated bedrock well heads were also 

generally more sensitive to the HK parameters in the adjacent 

upland areas than to the bedrock HK parameters, probably 

because the surficial unit HKs control the outflows of water 

from the bedrock and therefore the heads. The simulated heads 

in the till wells were sensitive to the RCH_Till and HK_Till 

parameters in general, although individual till well heads were 

quite sensitive to HK parameters in nearby sandy areas, and in 

the RCH_Sandy1 and RCH_Sandy2 parameters.

The 22 individual base-flow simulated values were 

sensitive to many different parameters. Most of the base-flow 

simulated values were quite sensitive to the RCH_Sandy1 

parameter. The simulated base flows at the Merriland River 

sites were generally insensitive to the model parameters, but 

they were sensitive to the layering of the model and spatial 

distribution of the geologic units. The simulated base flows at 

the three tributaries to the Mousam River were most sensitive 

to the HK_Delta2 and RCH_Sandy2 parameters but only 

mildly sensitive to the KDR parameters. The simulated base 

flows in the Branch Brook reaches were sensitive to several 

parameters (besides RCH_Sandy1), including RCH_Sandy2, 

KDR_Seeps, HK_L1Rock, HK_Presump, and HK_Delta2.

The homeowner dug wells in the sandy units and, to 

a lesser extent, the till and bedrock wells had some of the 

greatest individual influence on the model calibration, likely 

because they were widely distributed across the model area 

(appendix 2). Monitoring wells that were in some of the 

clustered areas had less influence in general, except for some 

of the monitoring wells near the Merriland and Herrisecket 

pumping wells. The base-flow observations contributed less 

of an influence on the parameter estimation process than the 

head observations. 
Simulation of Groundwater Flow and Discharge to Streams 39

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Residuals on simulated heads, 

in feet

less than 10.0

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-4.9 to -2.5

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2.51 to 5.0

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greater than 10.0

Production well, pumping rate

in gallons per minute

6 to 20

21 to 500

501 to 1000

Groundwater model

Model RIV cells

Model DRN cells

Model rows and 

columns

120

Active model boundary

EXPLANATION

0 10.5 2 3 4 KILOMETERS

0 0.5 1 2 3 4 MILES

Figure 16. Spatial distribution of head residuals for the model domain in the area in and around the Branch Brook watershed in 

southern Maine.
40 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

0

1

2

3

4

5

6

7

8

9

10

BB #7BB #6

BB #5

BB #4BB #3

BB#2

BB #1

Perkins Marsh

Cold Water

Day Brook

BB #8

Merri #1Merri #2

Base flow, in cubic feet per second

Base flow observation

EXPLANATION

Lower 95th confidence interval

on observed base flows

Upper 95th confidence interval

on observed base flows

Model-simulated base flows

Observed base flows

Figure 17. Steady-state observed and model-simulated base flow (groundwater discharge), with confidence intervals on the observed 

values, for the area in and around the Branch Brook watershed in southern Maine.

The use of parameter estimation also provides 

information on the confidence intervals of the parameter 

estimates for model variables determined using this process. 

The estimates are shown in figure 19 along with the 95-percent 

confidence intervals and reasonable ranges for the estimated 

15 parameters. Ideally, the parameter confidence intervals 

would be small and would fall entirely within the reasonable 

ranges. Prior modeling studies have shown, however, that 

a large degree of uncertainty in most parameter values is 

quite common (Mary Hill, U.S. Geological Survey, written 

commun., 2011). Most of the parameters were estimated 

within their reasonable ranges, and the confidence intervals for 

nine of them fell entirely within the reasonable ranges. Only 

one was estimated outside the reasonable range (RCH_Till), 

although earlier runs of the estimation process attempted to 

set the RCH_Sandy1 parameter (not shown) far outside its 

reasonable range, so that parameter was instead set by hand.

Model-Calculated Water Budget for Branch 

Brook, the Merriland River, and Lower Mousam 

River

The simulated average annual water budget for the 

Branch Brook, Merriland River, and lower Mousam River 

watershed areas in the model were calculated using the 

MODFLOW supplemental software ZONEBUDGET 

(Harbaugh, 1990), which is used to calculate internal flows 

between different zones of the model. This allows for detailed 

summarizing of the cell-by-cell flows across different parts 

of the model and interactions with boundaries and stresses. 

The ZONEBUDGET zones set up for the model followed 

the watershed boundaries and included the surficial units 

(layers 1 through 5) in each of the three watersheds. In the 

areas where bedrock is at or near land surface, the shallow 

bedrock is included in the surficial ZONEBUDGET zones. 

The deeper bedrock (layers 6 and 7, and layers 2 through 5 in 
Simulation of Groundwater Flow and Discharge to Streams 41

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B. Layer 4

A. Layer 1

EXPLANATION

Line of equal 

head—Layer 1

Groundwater flow 

directions—Layer 1

General head boundaries

Model rows and columns 20

Rivers and streams

Active model area

6 to 20

21 to 500

501 to 1,000

Production well,

pumping rate in 

Gravel aquifer in layer 4 gallons per minute

Groundwater flow directions 

—Layer 4

Line of equal head—Layer 4

0 10.5 2 3 4 KILOMETERS

0 0.5 1 2 3 4 MILES

0 10.5 2 3 4 KILOMETERS

0 0.5 1 2 3 4 MILES

Figure 18. Simulated steady-state groundwater heads and flow directions in A, layer 1 and B, layer 4 of the groundwater flow 

model of the area in and around Branch Brook watershed in southern Maine. Contour interval 10 feet. 
42 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

0.001

0.01

0.1

1

10

100

1,000

HK_Alluv

HK_BurGrav

HK_Coarse

HK_Delta2

HK_L1ROCK

HK_MrnSand

HK_PmUndif

HK_Presump

HK_Till

HK_ClayEXP

RCH_Till

RCH_Bedrock

KDR_Seeps

KDR_Stream

RCH_Sandy_2

Model parameter value

Parameter name

EXPLANATION

Reasonable range

for parameter values Estimated parameter values, with

95-percent confidence intervals

Figure 19. Final calibrated model parameter values, 95-percent confidence intervals, and reasonable ranges for hydraulic 

conductivity and recharge values for the groundwater flow model of the area in and around the Branch Brook watershed in southern 

Maine.

shallow bedrock areas) was set up as a separate zone to test 

the amount of groundwater interaction with the bedrock units. 

The constant head in the ocean also was set up as a separate 

zone. Flows reported here are the net fluxes of water across 

the boundaries of the various zones. The detailed accounting 

for fluxes of water between the three watersheds and the 

boundaries (table 16) indicates that for the model overall, 

recharge to the surficial units (97 percent) and inflows across 

the GHB boundaries (3 percent) are the sole inputs to the 

model. Outflows from the model, as a whole, are to surfacewater bodies (89.9 percent), pumping wells (8 percent), GHB 

boundaries (2.4 percent), and the ocean (less than 0.5 percent).

Flow between the surficial aquifer (or shallow bedrock 

where the surficial sediments are less than 25 feet thick) and 

the underlying bedrock accounts for between 7 and 11 percent 

of total fluxes in and out of the surficial units. The Merriland 

River and Mousam River watersheds, being on the edges of 

the model area, had the primary interactions with the GHB 

boundaries (fig. 18), being approximately 6 and 3 percent of 

the flux in those watersheds, respectively. Net inflows from 

GHB boundaries into the Mousam River watershed were split 

between the GHB boundary on the northwest edge of the 

model (65 percent of the GHB inflow) and the smaller one 

that simulates flow within the buried gravel aquifer under the 

Mousam River (35 percent). The southern edge of the Merriland River watershed is bounded by GHB boundaries in four 

locations where sand and gravel aquifers cross the topographic 

divide (figs. 1 and 11). The net total flow across all these GHB 

boundaries is fairly small (table 16), but the inflows across 

this watershed occur dominantly in the buried gravel aquifer 

in the coastal plain (towards the pumping well), whereas the 

outflows occur along the upland GHB boundaries.
Simulation of Groundwater Flow and Discharge to Streams 43

Table 16. Steady-state model calculated water budget fluxes for the Branch Brook area groundwater flow model and 

three primary watersheds within the model area.

[ft3/d, cubic feet per day; GHB, general head boundary; GW, groundwater; --, not applicable; numbers in parentheses indicate negative flows]

Hydrologic budget component

Rate of flux, in ft3/d

Model domain Branch Brook 

watershed

Merriland River 

watershed

Mousam River 

watershed area

Inflows

Recharge to surficial units1 4,532,656 1,751,205 813,024 1,968,426

Inflows from GHB boundaries 132,749 702 56,372 75,675

Interbasin GW flows -- 223,662 133,100 133,042

Inflows from bedrock units -- 203,830 118,984 166,629

Outflows

Discharge to surface-water features (4,077,654) (1,640,361) (681,393) (1,755,900)

Pumping (359,725) (70,000) (195,970) (93,755)

Discharge to ocean (1,041) (2,467) 0 1,425

Interbasin GW flows -- (266,134) (61,734) 161,928

Flows to bedrock units -- (199,979) (101,949) (158,918)

Outflows to GHB boundaries (112,178) (1,225) (52,818) (58,136)

Net GHB flux 20,570 (523) 3,554 17,539

Net bedrock flux -- 3,852 17,035 7,711

1

Does not include recharge applied to ocean.

There is a notable amount of groundwater flux between 

the three watersheds within the surficial units, which accounts 

for about 12 percent of the flows in and out of the surficial 

units of the Branch Brook aquifer, and about 11 and 7 percent, 

respectively, for the Mousam and Merriland River watersheds. 

Much of the flux between the Branch Brook and Merriland 

River watersheds occurs within the buried gravel aquifer in 

layers 4 and 5 (fig. 18). The fluxes between the watersheds are 

combined with the GHB flows in the “GW-surficial” inflow 

and outflow categories in figure 20. Internal fluxes between 

the surficial and bedrock units in each watershed area are 

not shown on figure 20, only the net flows in and out of each 

watershed. Outflows from bedrock in the Mousam River 

watershed (fig. 20) discharge to river and drain cells and to 

the ocean.

Scenario Testing

The groundwater model was used to evaluate several 

different hydrologic conditions, or scenarios, that could 

change the amount of groundwater flowing to the rivers and 

streams in the study area. The scenarios were (a) no pumping 

from the water-supply wells; (b) current (as of 2013) pumping 

from the water-supply wells, but simulated drought conditions 

(25 percent reduction in recharge); (c) current recharge, but 

with increased pumping from the large water-supply wells; 

and (d) drought conditions and increased pumping combined. 

The simulation without any water-supply wells (including 

the SWD and KKWWD wells) was used as a “natural” 

flow scenario against which the base flows with the current 

pumping were compared to derive the base-flow depletion 

amounts in the rivers. The increased pumping scenarios used 

pumping rates for the KKWWD wells that were close to the 

maximum rates that the wells are able to pump. The rate for 

the SWD wells was 150 percent of its current (2013) pumping 

rate. The small community water-supply pumping rates were 

not increased for the scenarios.

Use of the Groundwater Model to Determine 

Groundwater Divides and Flow Directions

At the beginning of the study, there were uncertainties 

about the position of the groundwater divides between the 

Branch Brook, Merriland River, and Mousam River watersheds because of the low-relief topography in the sand plains 

that separated the watersheds. There were also questions about 

how pumping in the Sanford area would affect the position 

of the water table and whether groundwater could flow from 

the Branch Brook watershed to the Mousam River watershed 

under pumping or nonpumping conditions. The calibrated 

groundwater flow model was used to address these questions.
44 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

-2,000,000

-1,500,000

-1,000,000

-500,000

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

Branch Brook Merriland River Mousam River

Flux, in cubic feet per day

Watershed 

INFLOWS

OUTFLOWS

Shallow groundwater crossing 

watershed boundary

Outflows to:

Inflows from:

EXPLANATION

Recharge

Shallow groundwater crossing 

watershed boundary

Surface water

Pumping wells

Flow to or from bedrock

Figure 20. Steady-state simulated inflows and outflows for the Branch Brook, Merriland River, and Mousam River watershed areas in the 

groundwater flow model of the area in and around the Branch Brook watershed in southern Maine.

The head contours in layer 1 represent the water table and 

are appropriate for the delineation of groundwater divides and 

flow directions in relation to the watershed divides in the headwater areas of Branch Brook and the divides between Branch 

Brook and the Mousam River watershed to the north and the 

Merriland River watershed to the south (fig. 21A). Under the 

normal (pumping) conditions, the groundwater divide between 

Branch Brook and the Mousam River is more of a straight line 

than the topographic divide, and groundwater flow crosses 

the topographic divide in both directions along this border. 

The largest difference is in the northwestern most part of the 

Branch Brook watershed, where the groundwater divide is 

almost one-half mile farther to the south than the topographic 

divide, and a significant amount of water flows across the 

topographic divide north into the Mousam River watershed 

and towards the Sanford withdrawal well (fig. 21A). However, 

under the no-pumping scenario, the groundwater divide still 

falls to the south of the topographic divide (fig. 21A). The 

pumping well in Sanford therefore has a small effect on the 

flow directions and groundwater flow divides under the current 

pumping rates and captures a small amount of groundwater 

from the Branch Brook watershed. The water-budget analysis 

concluded that from 7 to 12 percent of the entire water budgets 

of the three watersheds consisted of groundwater flows across 

watershed boundaries but that most of this flow crosses the 

watershed boundaries in the vicinity of the Merriland River 

pumping well, within the buried gravel aquifer. The amount 

crossing the watershed boundaries in the headwater areas is 

correspondingly a small portion of the total.

The movement of the groundwater divide under 

drought conditions with additional pumping is illustrated in 

figure 21B. Under this scenario, there is a significant further 

deflection of the groundwater divide towards Branch Brook 

with more groundwater flowing to the north and the Mousam 

River watershed. Under this scenario, the groundwater 

divide is deflected about three-quarters of a mile south of 

the topographic divide. The changes in the groundwater 

divide between this scenario and the base case shown in 

figure 21A are primarily because of the reduction in recharge, 

especially in areas not immediately adjacent to the Sanford 

pumping wells.

The differences between the groundwater divide and the 

topographic divide in the area that separates Branch Brook 

from the Merriland River to the south are somewhat less pronounced and do not indicate any significant deviation between 

the pumping and no pumping scenarios.
Simulation of Groundwater Flow and Discharge to Streams 45

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Branch Brook watershed

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watershed

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watershed

0 0.5 1 2 MILES

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EXPLANATION

Edge of modeled area

Groundwater divide, no pumping

Rivers and streams

Watersheds from surface topography Groundwater divide

Normal pumping scenario

Flow directions

Line of equal head—Layer 1

Production well, 

pumping rate in 

gallons per minute

6 to 20

Line of equal head—Layer 1 21 to 500

Less recharge and increased 

pumping scenario

Flow directions

Groundwater divides

Model rows and columns 180

A. Normal pumping and no pumping

B. Less recharge (drought) and increased pumping

0 0.5 1 2 MILES

0 0.5 1 2 KILOMETERS

Figure 21. Groundwater divides and flow directions from simulated heads compared to topography-based watershed 

divides in the headwaters of the Branch Brook watershed in southern Maine: A, normal pumping and no pumping scenario 

and B, less recharge (drought) and increased pumping scenario.
46 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

Evaluation of Streamflow Depletion in 

Branch Brook and the Merriland River

A reduction in streamflow resulting from a groundwater 

withdrawal is known as streamflow depletion. Estimating 

the amount of streamflow depletion at a particular location 

caused by a groundwater withdrawal requires knowing how 

that withdrawal propagates through an aquifer to the river or 

stream. The cumulative effect of groundwater pumping by 

wells in the headwaters and near the mouths of Branch Brook 

and the Merriland River was calculated using the groundwater 

flow model.

Simulation of Streamflow Depletion Using the 

Groundwater Flow Model

Streamflow depletion resulting from pumping was 

calculated as the difference between streamflow (discharge 

to RIV and DRN cells) with no pumping (no simulated 

withdrawals from the calibrated model) and streamflow 

with pumping (the base-case calibrated model). Streamflow 

depletion was calculated for three of the streamflow 

measurement and streamflow observation locations: BB#6 

(station 01069645), which represents the headwaters of 

Branch Brook; BB#1 (station 01069725), which is the 

farthest downstream site on Branch Brook and is near several 

withdrawal wells; and Merri#1 (station 01069780), which 

is the farthest downstream site on the Merriland River and 

is downstream from the withdrawal wells. In addition to 

the streamflow depletion using the base pumping rates, the 

streamflows with no pumping were compared to streamflows 

under drought conditions, with increases in pumping, and with 

drought and increased pumping combined.

The streamflow depletion calculations derived from the 

steady-state model assume that the pumping is constant, which 

is not the case for all the wells. The wells in the headwaters 

of Branch Brook pump year round, so the calculation of 

streamflow depletion for the headwater site is assumed to 

be valid for the entire year. The wells in the coastal plain, 

however, do not pump year round. Streamflow depletions may 

last well beyond the period of pumping in many situations 

(Barlow and Leake, 2012), but given the short distances 

between the wells in the coastal plain area and the rivers (less 

than 1⁄2 mile) and the fast rebound of streamflows after the 

cessation of pumping in wells near rivers in similar settings 

in Maine (Dudley and Stewart, 2006), the streamflows may 

return to their natural state shortly after the withdrawals end 

for the season. Therefore, the depletion calculations apply 

primarily to the pumping months, which are primarily April 

through November for the Merriland River wells and June 

through August for the wells closer to Branch Brook. Transient 

simulations of the groundwater, streamflow, and pumping in 

the study area would be useful to indicate more precisely how 

long the streamflow depletion is likely to last in Branch Brook 

and the Merriland River after pumping ceases. The streamflow 

depletion simulated with the groundwater model is considered 

to represent a maximum expected amount of depletion for the 

June base flows simulated in the model.

Streamflow depletion in the headwaters of Branch Brook 

at site BB#6 was 0.12 ft3/s for the steady-state simulation, 

or about 10 percent of the total simulated base flow at that 

location (table 17). This is consistent with the finding that the 

Sanford pumping well had a small effect on the location of 

the groundwater divide, moving it farther south and capturing 

some of the flow in the Branch Brook watershed area. 

Downstream on Branch Brook at BB#1, the total streamflow 

depletion from all the wells was 0.59 ft3/s, or 3 percent of 

the total simulated base flow at that location (although the 

simulated base flow, at 18.1 ft3/s, is higher than the estimated 

August median flow of 11.8 ft3/s). Most of that depletion 

was the result of pumping in the wells near Branch Brook, 

as model simulations without the Merriland River wells did 

not change the amount of depletion in Branch Brook. In the 

Merriland River at Merri#1, the total amount of streamflow 

depletion was 0.6 ft3/s, or about 7 percent of simulated base 

flow (table 17). This amount of streamflow depletion is caused 

by pumping in the Merriland River well, as simulations 

without the wells near Branch Brook did not alter this amount.

The model was run with simulated increases in the pumping rates in each of the wells, as described in the section on 

scenario testing. The streamflow depletion by pumping in the 

headwaters at BB#6 increased to 0.19 ft3/s, or 16 percent of 

the flow at that site (table 17). Increases in the pumping in the 

coastal plain wells increased the amount of streamflow depletion to 1.0 ft3

/s at BB#1 (6 percent of the flow) and to 0.72 ft3/s 

at Merri#1 (8 percent of the flow).

The additional stress of a drought imposed on the model 

(25 percent less recharge) had a significant effect on streamflows, as would be expected. The reduction in streamflows 

from the simulated drought (not streamflow depletion) was 

0.42 ft3/s (38 percent reduction) at BB#6, 3.8 ft3/s (23 percent 

reduction) at BB#1, and 2.1 ft3/s (27 percent reduction) at 

Merri#1. It is interesting to note that the reduction in recharge 

had a disproportionately large effect on streamflows in the 

headwaters and a somewhat disproportionately large effect in 

the Merriland River. When compared to the normal recharge 

simulation without pumping, the streamflow in these river 

reaches was reduced by 34, 23, and 25 percent, respectively.

If the simulated drought occurred simultaneously with 

an increase in pumping, the simulated declines in streamflows 

would be 0.58 ft3/s (a 48-percent reduction in flow from the 

no-pumping scenario) in the headwaters at BB#6. Downstream 

in Branch Brook at BB#1, the total reduction in flow would 

be 4.9 ft3/s, which is 29 percent less than the no-pumping 

scenario. In the Merriland River, the reduction would be 

2.8 ft3/s, or a 33-percent reduction from the no-pumping 

scenario (table 17).

Because the groundwater model simulates streamflow 

(base flow) at all the Branch Brook streamflow sites, the differing effects of pumping and drought can be graphed going 
Evaluation of Streamflow Depletion in Branch Brook and the Merriland River 47

Table 17. Model-calculated streamflow depletion in Branch Brook and the Merriland River.

[ft3/s, cubic feet per second]

Scenario

Streamflow site

Branch Brook 

headwaters 

(BB#6)

Branch Brook 

at intake 

(BB#1)

Merriland River 

near mouth 

(Merri#1)

Total streamflow (in ft3/s)

Model-calculated steady-state with existing pumping 1.1 16.5 7.9

Predicted steady-state without pumping 1.2 17.1 8.5

Predicted with pumping increased 1.0 16.1 7.8

Predicted with 25 percent less recharge, existing pumping 0.68 12.7 5.8

Predicted with increased pumping and 25 percent less recharge 0.62 12.2 5.7

Streamflow depletion1

Model-calculated steady-state with existing pumping 0.12 0.59 0.60

Predicted with pumping increased 0.19 1.0 0.72

Predicted with 25 percent less recharge, existing pumping 0.52 4.5 2.7

Predicted with increased pumping and 25 percent less recharge 0.58 4.9 2.8

1

Difference between no pumping and the other scenarios (in ft3/s).

downstream from the headwaters to the station at BB#1 

(fig. 22). It is clear that in terms of magnitude of effect, the 

reduction of recharge (drought) has a much greater influence on streamflow than does pumping, suggesting that base 

flows in Branch Brook are sensitive to drought. The effect 

of groundwater withdrawals is evident primarily in the river 

reach between the USGS streamgage (station 01069700 at 

BB#2) and downstream at site BB#1 (station 01069720). 

Under the maximum pumping and drought scenario, the line 

between those two stations is almost flat (fig. 22), indicating 

that groundwater discharge (base flow) along that reach would 

almost cease.

Comparison of Streamflow Depletion Estimates 

to In-stream Flow Requirements

The water resources of Branch Brook have been used as 

a drinking-water source for many years, as described in the 

introduction. The groundwater model was used to put those 

withdrawals into context with the monthly in-stream flow 

requirements, monthly estimated flows, and streamflow depletion from groundwater pumping.

Figure 23 illustrates the combined effects of simulated 

pumping, direct withdrawals from Branch Brook, and 

simulated drought as applied to the monthly median 

estimates of streamflow in Branch Brook throughout the 

course of a year, in comparison with the State in-stream 

flow requirements. The monthly median flows in Branch 

Brook estimated using the MOVE.1 regression technique 

are shown, along with estimates of streamflow if there had 

been no groundwater pumping. The effect of drought on the 

streamflows is added to show how that might change the 

hydrograph throughout the year (assuming that the effect 

does not vary by month). The effect of the direct withdrawals 

downstream from the public supply intake at BB#1 is shown 

as well, and during the summer months, the flows below the 

intake can be a fraction of the unaffected flows. Because this 

effect has been directly observed by the water district in the 

past, they are actively seeking out alternative sources of water 

to use during the summer months (Scott D. Minor, Assistant 

Superintendent, Kennebunk, Kennebunkport and Wells Water 

District, oral commun., 2012).

As noted earlier in the section on the calculation of instream flow requirements, the two methods of determining 

in-stream flow requirements (based on August median flows) 

differ widely, with the MOVE.1 regression resulting in more 

realistic estimates than using the statewide flow equations. The 

streamflow depletion in Branch Brook simulated by the model 

would be 5 percent of the MOVE.1 August median (11.8 ft3/s). 

In the Merriland River, the simulated streamflow depletion of 

0.6 ft3/s is approximately 20 percent of the MOVE.1 August 

median (3.07 ft3/s).

Limitations of the Model

The groundwater flow model simulates groundwater 

levels, flow, and discharge in the study area. This model is not 

designed to simulate chemical transport, although it could be 
48 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

BB#7

BB#6

BB#5

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BB#1

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Model-simulated base flow, 

in cubic feet per second

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Reduced recharge, maximum pumping

Reduced recharge, no pumping

Base, reduced recharge

Base calibrated model

Maximum pumping

No pumping

EXPLANATION

Figure 22. Model-simulated base flow in Branch Brook from the headwaters to the end, showing the effects of pumping and drought, 

southern Maine.

adapted for that purpose. As with any numerical simulation of 

a natural system, the model incorporates simplifications and 

assumptions about the natural system that create uncertainty in 

model results. Some of the simplifications include the assumption that the water levels and base flows represent true steadystate conditions and that geology is adequately represented by 

parameter values in the assigned zones.

The river and stream network is simplified from reality, and the modeled streambed conductance and riverbed 

conductance incorporate highly simplified representations of 

the width of each stream segment. The discretization of the 

stream network also assumes a straight-line segment in each 

model cell, which may differ significantly from reality. The 

water-level elevations in each model cell are interpolated 

from the topography in a way that may not represent each 

individual stream segment accurately. Most importantly, the 

known quantities for the base-flow observations (total flows at 

the 13 monitoring locations) had to be divided into individual 

DRN and RIV observations in the model. This was done using 

the modeler’s best judgment for each segment but not by any 

measurements. Although the uncertainties of each of these 

individual DRN and RIV observations was adjusted upwards 

significantly to account for this, they still remained arbitrary 

divisions. The parameter estimation, therefore, may have 

given individual DRN or RIV observations more weight than 

warranted in determining the best fit between the observations 

and parameter estimates.

Additional stratigraphic data would have helped to 

make the movement of water more certain, particularly in the 

coastal plain area of the model. The extent of the buried gravel 
Evaluation of Streamflow Depletion in Branch Brook and the Merriland River 49

Jan. Feb. Mar. April May June July Aug. Sept. Oct. Nov. Dec. 

Streamflow, in cubic feet per second

0

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Winter

Spring

Early 

summer

Late summer

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Early

winter

EXPLANATION

Direct withdrawals from Branch Brook

Potential flows in drought conditions

Medians adjusted for withdrawals and depletion

Calculated median flows in Branch Brook, using the

MOVE.1 regression technique

"Natural" flows

"Standard" seasonal in-stream flow requirements

Figure 23. Calculated monthly streamflows in Branch Brook and projections of streamflows accounting for direct withdrawals, 

streamflow depletion from pumping, and drought, southern Maine.

aquifer in the coastal section is largely based on a geometry 

that provided the best fit between the observed and simulated 

water levels, rather than on actual boring or well data (all the 

well data that did exist were used in the delineation of this 

aquifer area). Also, the fact that this aquifer apparently extends 

beyond the model boundary to the south limits the accuracy 

of the model with respect to predictions of changes in water 

levels and fluxes to changes in stresses (pumping) so close to 

this model boundary.

There is other evidence of some model error in the central 

part of the Branch Brook watershed. The base-flow observations in this part of the model are extremely sensitive to 

several recharge parameters, but the recharge parameter with 

the greatest model sensitivity had to be constrained within the 

reasonable bounds as determined from prior information and 

could not be estimated. If the model construction perfectly 

matched the physical reality, the parameter estimation would 

derive best estimates for the recharge rates that fell within a 

reasonable range. This error could be either because of some 

undetected geologic factor that was not accounted for in the 

model or because of errors in the method used to calculate the 

base-flow observations.

The analysis of the model sensitivities noted earlier 

suggests that improvements to the model could be made with 

some additional data collection. This could include additional 

drilling to determine the extent and geologic nature of the 

buried gravel aquifer in the coastal plain area; collecting independent measurements of recharge in the study area, particularly in the Branch Brook, Cold Water Brook, and Day Brook 

watersheds; and additional drilling between Day Brook and 

Branch Brook to better determine the stratigraphy and extent 

of the Presumpscot Formation in that area.

The use of a steady-state model to simulate processes 

that change with the seasons, and pumping rates that are not 

constant, presents some limitations to the final results, as the 

streamflow depletion amounts that would be obtained from a 

transient model would likely differ somewhat from the steadystate streamflow depletion described in this report. A transient 

model also would be more suited to understanding the temporal effects of pumping on the rivers and stream and would be 

able to determine how long the streamflow depletion lingers 

after pumping ceases.
50 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

Summary and Conclusions

The Branch Brook watershed area in the towns of 

Kennebunk, Wells, and Sanford, Maine, was investigated in 

2010 and 2013 under a cooperative project between the U.S. 

Geological Survey (USGS) and the Maine Geological Survey 

to investigate the effect of water withdrawals on watersheds 

having a large amount of permitted withdrawals relative to 

their size. The study area, located in southern coastal Maine, 

includes the Branch Brook watershed, the adjacent Merriland River watershed to the south, and extends north to the 

Mousam River, which forms the northern boundary of the 

study area. This investigation provides an illustration of the 

effects that large withdrawals can have on hydrologic processes in Maine watersheds and evaluates the cumulative 

effect of several withdrawals on a relatively complex sand 

and gravel aquifer system. A steady-state groundwater flow 

model was used to evaluate the water budget, to understand 

the movement of water within the system, and to assess the 

effect that groundwater withdrawals have on streamflows. This 

study, like an earlier study under the cooperative project, is 

intended to provide insight into the effect of withdrawals on 

streamflows under a certain set of conditions (that is, the aquifer geometry presented by the specific study area) and to help 

understand streamflow depletion in light of the State requirements to maintain in-stream flows for habitat protection. The 

groundwater flow model was used to simulate the present 

(2013) withdrawal situation as well as scenarios that included 

drought conditions and future increased pumping.

There are four large water-supply wells in the study 

area, four small water-supply wells, and 1,751 self-supplied 

domestic wells. The large water-supply wells in the study area 

withdraw a total of 658.8 million gallons per year (Mgal/yr), 

and a surface-water withdrawal in Branch Brook withdraws 

590 Mgal/yr. One of the largest groundwater withdrawals is 

located just outside the Branch Brook watershed boundary, 

and one objective of the study was to understand if and how 

much effect that well has on the location of the groundwater 

divide and flow in Branch Brook.

The geologic units in the study area include fractured 

crystalline bedrock and stratified, unconsolidated glacial and 

post-glacial deposits that are draped over the bedrock. The 

glacial deposits include till (in moraines and as a blanket 

deposit), stratified marine sand and gravel, marine silt and 

clay, beach and nearshore sand and gravel deposits, and sandy 

deltaic deposits.

The surficial deposits provide most of the available 

groundwater resource for human use. The hydrogeologic 

units supplying groundwater to the public supply wells, 

irrigation wells, and to a lesser extent, domestic wells, are 

primarily sands and gravels of a large set of ice-contact and 

marine deltaic deposits and nearshore marine deposits. A 

previously unmapped buried gravel aquifer that appears to 

supply most of the water to the Merriland River well trends 

northeast-southwest under the coastal plain, and crosses the 

model boundary to the south. In the central and western part 

of the study area, the topography is very flat, and the relative 

positions of the groundwater and surface-water divides 

between the headwaters of Branch Brook, the Mousam River 

watershed, and the headwaters of the Merriland River are 

difficult to ascertain. Groundwater levels were measured in 

130 wells in the study area in June 2012. The wells were a 

mix of monitoring wells and homeowner wells. One long-term 

groundwater monitoring well operated by the USGS since 

1988 provided context for the hydrologic conditions during 

the water-level survey.

Streamflow was measured at 13 locations in the study 

area from June 2010 to April 2012, including 5 sites on the 

main stem of Branch Brook. Estimates of long-term monthly 

flows were made using the MOVE.1 record-extension techniques on 16 to 17 measurements at each location.

Surface-water withdrawals in the study area in 2010 were 

primarily withdrawals from Branch Brook, in the amount of 

590 million gallons (Mgal). Agricultural irrigation from surface-water ponds was estimated to be about 9 Mgal. Permitted 

groundwater withdrawals totaled 384.3 Mgal in the Merriland 

River watershed, 231.5 Mgal in the Mousam River watershed, 

and 32.2 Mgal in the Branch Brook watershed. Domestic withdrawals from private wells were split fairly evenly between 

the watersheds and were 90 Mgal in total. Commercial and 

industrial water use in the study area is small in relation to 

these other uses and was estimated to total 2.3 Mgal.

The groundwater modeling component of the study was 

used to better understand groundwater flow and the interaction of groundwater with streamflow in the study area. A 

steady-state groundwater model was constructed using the 

three-dimensional, finite-difference groundwater flow modeling code, MODFLOW–2005. This model was used to simulate flow in the unconsolidated glacial deposits and shallow 

bedrock units.

The model area was discretized into a grid of 443 rows 

and 214 columns of cells with uniform 150-foot (ft) spacing. The seven-layer model was used to simulate flow in the 

bedrock under the glacial deposits (two layers), a middle 

zone including productive aquifers in the eastern and western 

parts of the study area and a confining unit in the central and 

eastern parts of the study area (three layers), and an upper 

zone consisting of the shallowest sand and gravel deposits, till, 

and shallow bedrock in upland areas with thin unconsolidated 

materials over bedrock (two layers). The upper two layers 

were modeled as unconfined. The land surface was set as the 

top of the uppermost layer (layer 1). The lateral model boundaries were primarily no-flow boundaries on upland surfacewater divides. The Atlantic Ocean was modeled as a constanthead boundary on the eastern edge. Although the watershed 

boundary was used for most of the groundwater model 

boundary, significant sand and gravel aquifers are mapped 

crossing the watershed boundary in several locations, where a 

general head boundary (GHB) was used instead of a no-flow 

boundary. The southern end of the buried gravel aquifer in the 

coastal plain area also was modeled with a GHB boundary. 
Summary and Conclusions 51

Data from monitoring wells and surface-water bodies were 

used to set the heads at these boundaries.

Recharge was applied in the model to the top active cell. 

Recharge rates ranged from less than 3 inches/year (in/yr) in 

the shallow bedrock and wetland settings to approximately 

30 in/yr in the very coarse-grained soils that cover much of 

the study area. Although this is considered a relatively high 

recharge rate for southern Maine, other investigators have 

corroborated this high rate in the study area. Pumping was 

simulated in the model for all the water-supply wells. The 

surface-water system was modeled using both the Drain package and River package in MODFLOW.

The model was calibrated using a mix of parameter 

estimation of hydraulic properties and recharge rates and trialand-error adjustments to the conceptual model of the groundwater system, as well as some of the hydraulic properties and 

recharge rates. Groundwater level observations were acquired 

from the water-level survey of June 2012 and surface-water 

elevations in wetlands and ponds. Stream- and river-flow 

observations were mid-summer (June and July) base flows 

in the 13 streamflow measurement sites, determined by use 

of record-extension techniques. Hydraulic properties and 

recharge rates were set within a reasonable range established 

by prior studies and literature values.

The mean difference between the observed and simulated 

heads is 1.4 ft, and the mean absolute difference between 

the observed and simulated heads is 4.0 ft. Given the range 

in observed heads over the model area of 282 ft, these errors 

represent 0.5 and 1.4 percent, respectively, of the total head 

change across the model. The simulated streamflows at the 

13 observation sites were almost all within the 95-percent 

confidence intervals of the observation target flows.

The simulated average annual water budget for the 

Branch Brook, Merriland River, and lower Mousam River 

watershed areas in the model were calculated using the 

MODFLOW supplemental software ZONEBUDGET. Flow 

across the surface-water divides between the headwaters 

of Branch Brook, the Mousam River watershed, and the 

headwaters of the Merriland River accounted for between 

7 and 12 percent of the overall budgets of the watersheds. 

Mapping of the simulated water-table divides compared to the 

surface-water divides confirmed that the groundwater divides 

in this area of low topography do not exactly correspond to the 

surface-water divides.

The groundwater model was used to evaluate several 

different scenarios that could change the amount of groundwater flowing to the rivers and streams in the study area. The 

scenarios were (1) no pumping from the water-supply wells; 

(2) current (as of 2013) pumping from the water-supply wells, 

but simulated drought conditions (25 percent reduction in 

recharge); (3) current recharge, but with increased pumping 

from the large water-supply wells; and (4) drought conditions 

and increased pumping combined. The simulation without 

pumping water-supply wells was used as a “natural” flow scenario against which the streamflows with the current pumping 

were compared to derive the streamflow depletion amounts in 

the rivers.

Streamflow depletion resulting from pumping was 

calculated as the difference between discharge to river and 

drain cells in the calibrated model with the no pumping 

scenario. Streamflow depletion was calculated for three of 

the streamflow measurement locations: the first represents the 

headwaters of Branch Brook (site BB#6), the second is the 

furthest downstream site on Branch Brook and is near several 

withdrawal wells (site BB#1), and the third is the furthest 

downstream site on the Merriland River and is downstream 

from the Merriland River withdrawal well (site Merri#1).

Streamflow depletion in the headwaters of Branch Brook 

at site BB#6 was 0.12 cubic feet per second (ft3/s) for the 

steady-state simulation, or about 10 percent of the simulated 

base flow at that location. Downstream on Branch Brook 

at BB#1, the total streamflow depletion from all the wells 

was 0.59 ft3/s, or 3 percent of the simulated base flow at that 

location. In the Merriland River at Merri#1, the total amount 

of streamflow depletion was 0.6 ft3/s, or about 7 percent 

of the simulated base flow. Under simulations of increased 

pumping, streamflow depletion in the headwaters at BB#6 

increased to 0.19 ft3/s, or 16 percent of the simulated base 

flow at that site. Increases in the pumping in the coastal plain 

wells increased the amount of streamflow depletion to 1.0 ft3/s 

at BB#1 and to 0.72 ft3/s at Merri#1. The additional stress of 

a drought imposed on the model (25 percent less recharge) 

had a significant effect on streamflows, as expected. The 

reduction in streamflows from the simulated drought (not 

streamflow depletion) was 0.42 ft3/s (37 percent reduction) at 

BB#6, 3.8 ft3/s (23 percent reduction) at BB#1, and 2.1 ft3/s 

(27 percent reduction) at Merri#1. If the simulated drought 

occurred simultaneously with an increase in pumping, the 

simulated declines in streamflows would be 0.58 ft3/s (a 

48-percent reduction in flow from the no-pumping scenario) 

in the headwaters at BB#6. Downstream in Branch Brook at 

BB#1, the total reduction in flow would be 4.9 ft3/s, which is 

29 percent less than the no-pumping scenario. In the Merriland 

River, the reduction would be 2.8 ft3/s, or a 33 percent 

reduction from the no-pumping scenario.

The pumping from the groundwater-supply wells in 

the coastal plain area is not year round. The streamflow 

depletion estimates for the Merriland River generally apply 

for the primary pumping season for that well, or April through 

November. The pumping wells are pumped for a shorter 

amount of time during the summer months, so the streamflow 

depletion estimates for the downstream Branch Brook site 

generally apply to June through September, although the 

exact period varies from year to year. The pumping in the 

headwaters of Branch Brook is year round, so the headwaters 

streamflow depletion estimates are assumed to be constant.

The August median in-stream flow requirement in 

the Merriland River was calculated as 7.18 ft3/s using the 

statewide equations but was 3.07 ft3/s using the MOVE.1 

analysis. In Branch Brook, the August median in-stream flow 

requirements were calculated as 20.3 ft3/s using the statewide 
52 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

equations and 11.8 ft3/s using the MOVE.1 analysis. In each 

case, analysis of site-specific data yields target median flows 

that are closer to actual conditions in the local streams than 

what the statewide equations provide, and which would therefore be easier for a regulated utility to maintain for meeting 

in-stream flow requirements. The State Chapter 587 requirements for in-stream flows does allow for using a third possible 

method of calculating in-stream flows using a geomorphic 

analysis, but doing so was not an objective of this study.

An analysis of summertime base flows in Branch Brook 

with the permitted surface-water withdrawals and simulated 

declines in flows under drought conditions indicates that the 

amount of water flowing in Branch Brook downstream from 

the withdrawal site could be about 23 to 29 percent less than 

the natural flows under normal conditions. The water utility 

in this area is already planning for increases in groundwater 

withdrawals in the greater region so that the surface-water 

withdrawals might be reduced.

The use of the groundwater flow model to map the 

groundwater divides and flow directions in the flat headwaters 

section has helped to understand the groundwater resources 

in these watersheds and can be used to better manage the 

resource. The scenario simulations run with the model indicated that the pumping well in the Mousam River watershed, 

near the headwaters of Branch Brook, does shift the groundwater divide towards the south several hundred feet, capturing a small amount (less than 0.2 ft3

/s) of groundwater from 

the Branch Brook watershed. The simulations of streamflow 

depletion in Branch Brook and the Merriland River indicate 

that the cumulative effects of pumping should be considered 

together to evaluate the overall effect on a given river or 

stream location.

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Appendix 1. Groundwater Observation 

Information
58 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

Table 1–1. Groundwater observation information, including well names, well depths, land surface altitude, and variances and weights 

used in the model.—Continued

[ft, feet; NAVD 88, North American Vertical Datum of 1988; σ2, variance]

Well name Model observation 

name

Observation 

group

Well 

depth, 

in ft

Land 

surface 

altitude, 

in ft above 

NAVD 88

Model 

layer

Measured 

water 

level, 

in ft above 

NAVD 88

Total 

variance 

(σ2), 

in ft

Weight, 

1/σ2

ME-YW 985 KKW MW-02 KKW_MW02 BB-North 23 211 1 196.8 0.263 3.804

ME-YW 986 KKW MW-07A KKW_MW07A BB-North 54 210 2 193.2 0.263 3.804

ME-YW 987 KKW MW-15 KKW_MW15 BB-North 36 181 2 166.3 0.263 3.804

ME-YW 988 KKW MW-23 KKW_MW23 BB-North 54 208 2 188.7 0.263 3.804

ME-YW 989 KKW MW-26 KKW_MW26 BB-North 38 211 1 194.4 0.263 3.804

ME-YW 990 KKW MW-30 KKW_MW30 BB-North 35 207 1 191.6 0.263 3.804

ME-YW 991 KKW MW-35 KKW_MW35 BB-North 35 207 1 182.1 0.263 3.804

ME-YW 992 KKW MW-48 KKW_MW48 BB-North 38 212 1 184.7 0.263 3.804

ME-YW 933 Nestle MW-01 Nestle_MW01 BB-North 20 199 1 192.4 0.521 1.921

ME-YW 934 Nestle MW-06 Nestle_MW06 BB-North 73 214 4 203.3 0.521 1.921

ME-YW 935 Nestle MW-13 Nestle_MW13 BB-North 81 210 5 192.9 0.521 1.921

ME-YW 936 Nestle MW-14 Nestle_MW14 BB-North 85 205 4 188.4 0.521 1.921

ME-YW 937 Nestle MW-16 Nestle_MW16 BB-North 64 205 3 164.7 0.521 1.921

ME-YW 938 Nestle MW-24 Nestle_MW24 BB-North 60 205 4 184 0.521 1.921

ME-YW 939 Nestle MW-33 Nestle_MW33 BB-North 64 208 3 189.7 0.521 1.921

ME-YW 940 Nestle MW-41 Nestle_MW41 BB-North 49 203 3 180.7 0.521 1.921

ME-YW 941 Nestle MW-44 Nestle_MW44 BB-North 55 203 2 186.6 0.521 1.921

ME-YW 942 Nestle MW-45 Nestle_MW45 BB-North 64 206 3 182.3 0.521 1.921

ME-YW 943 Nestle MW-46 Nestle_MW46 BB-North 41 211 1 197.9 0.521 1.921

ME-YW 944 Nestle MW-47 Nestle_MW47 BB-North 44 211 2 199.1 0.521 1.921

ME-YW 1002 TNC MW-101 TNC_MW101 BB-South 50 197 2 170.8 0.521 1.921

ME-YW 946 TNC MW-103 TNC_MW103 BB-South 50 191 4 170.9 0.521 1.921

ME-YW 1003 TNC MW-105 TNC_MW105 BB-South 25 196 1 181.2 0.521 1.921

ME-YW 1004 TNC MW-106 TNC_MW106 BB-South 25 192 2 185.6 0.521 1.921

ME-YW 947 TNC MW-107 TNC_MW107 BB-South 25 188 2 176.6 0.521 1.921

ME-YW 948 TNC MW-109 TNC_MW109 BB-South 15 191 1 185.8 0.521 1.921

ME-YW 949 TNC MW-110 TNC_MW110 BB-South 30 186 3 176.8 0.521 1.921

ME-YW 1000 TNC MW-202 TNC_MW202 BB-South 29.5 193 2 185.5 0.521 1.921

ME-YW 1001 TNC MW-204 TNC_MW204 BB-South 25 191 2 183.9 0.521 1.921

ME-YW 951 TNC MW-304 TNC_MW304 BB-South 19 195 1 189 0.521 1.921

ME-YW 953 TNC MW-308 TNC_MW308 BB-South 30 196 2 187.8 0.521 1.921

ME-YW 954 TNC MW-310 TNC_MW310 BB-South 30 197 2 185.8 0.521 1.921

ME-YW 999 TNC MW-315 TNC_MW315 BB-South 26 197 2 188.2 0.521 1.921

ME-YW 956 TNC MW-401 TNC_MW401 BB-South 30 198 1 187 0.521 1.921

ME-YW 993 TNC MW-403 TNC_MW403 BB-South 29 199 1 179 0.521 1.921

ME-YW 994 TNC MW-404 TNC_MW404 BB-South 39 198 3 180.6 0.521 1.921

ME-YW 957 TNC MW-410 TNC_MW410 BB-South 36 198 2 186.9 0.521 1.921

ME-YW 995 TNC MW-415 TNC_MW415 BB-South 30 199 2 182.6 0.521 1.921

ME-YW 959 TNC MW-422 TNC_MW422 BB-South 30 200 1 182.7 0.521 1.921
Appendix 1 59

Table 1–1. Groundwater observation information, including well names, well depths, land surface altitude, and variances and weights 

used in the model.—Continued

[ft, feet; NAVD 88, North American Vertical Datum of 1988; σ2, variance]

Well name Model observation 

name

Observation 

group

Well 

depth, 

in ft

Land 

surface 

altitude, 

in ft above 

NAVD 88

Model 

layer

Measured 

water 

level, 

in ft above 

NAVD 88

Total 

variance 

(σ2), 

in ft

Weight, 

1/σ2

ME-YW 996 TNC MW-425 TNC_MW425 BB-South 28 194 1 177.8 0.521 1.921

ME-YW 962 TNC MW-430 TNC_MW430 BB-South 30 195 1 179.1 0.521 1.921

ME-YW 997 TNC MW-433 TNC_MW433 BB-South 21 198 1 187.4 0.521 1.921

ME-YW 998 TNC MW-440 TNC_MW440 BB-South 20 195 1 184.5 0.521 1.921

ME-YW 870 ME_YW_870 Bedrock 260 161 7 112.9 0.521 1.921

ME-YW 878 ME_YW_878 Bedrock 73 159 6 146.5 0.521 1.921

ME-YW 882 ME_YW_882 Bedrock 75 208 4 206.2 0.521 1.921

ME-YW 883 ME_YW_883 Bedrock 700 179 7 175 0.521 1.921

ME-YW 888 ME_YW_888 Bedrock 300 273 7 254.2 0.521 1.921

ME-YW 891 ME_YW_891 Bedrock 244 36 7 6.3 0.521 1.921

ME-YW 894 ME_YW_894 Bedrock 300 31 7 15.7 0.521 1.921

ME-YW 895 ME_YW_895 Bedrock 300 122 7 108.8 0.521 1.921

ME-YW 896 ME_YW_896 Bedrock 300 95 7 87.7 0.521 1.921

ME-YW 897 ME_YW_897 Bedrock 500 173 7 168.1 0.521 1.921

ME-YW 901 ME_YW_901 Bedrock 200 175 7 151.3 0.521 1.921

ME-YW 871 ME_YW_871 Coastal sands dug 5 78 1 75.2 0.521 1.921

ME-YW 872 ME_YW_872 Coastal sands dug 10.6 81 1 76.8 0.521 1.921

ME-YW 873 ME_YW_873 Coastal sands dug 18.1 71 1 70.3 0.521 1.921

ME-YW 890 ME_YW_890 Coastal sands dug 9.8 34 1 28.7 0.521 1.921

ME-YW 892 ME_YW_892 Coastal sands dug 9.1 38 1 35.6 0.521 1.921

ME-YW 893 ME_YW_893 Coastal sands dug 10 33 1 29.2 0.521 1.921

ME-YW 906 ME_YW_906 Coastal sands dug 7.8 61 1 55.9 0.521 1.921

ME-YW 874 ME_YW_874 Delta sands dug 10.5 141 1 134.3 0.521 1.921

ME-YW 875 ME_YW_875 Delta sands dug 18 171 1 164.7 0.521 1.921

ME-YW 876 ME_YW_876 Delta sands dug 13.5 214 1 204.8 0.521 1.921

ME-YW 884 ME_YW_884 Delta sands dug 16 205 1 202.6 0.521 1.921

ME-YW 885 ME_YW_885 Delta sands dug 14.1 210 1 202.3 0.521 1.921

ME-YW 886 ME_YW_886 Delta sands dug 15 209 1 202.3 0.521 1.921

ME-YW 900 ME_YW_900 Delta sands dug 15 175 1 168.3 0.521 1.921

ME-YW 902 ME_YW_902 Delta sands dug 9.5 216 1 211.7 6.768 0.148

ME-YW 903 ME_YW_903 Delta sands dug 20 133 1 126 0.521 1.921

ME-YW 905 ME_YW_905 Delta sands dug 10.9 223 1 218 6.768 0.148

ME-YW 907 ME_YW_907 Delta sands dug 10.5 148 1 144.5 0.521 1.921

ME-YW 908 ME_YW_908 Delta sands dug 9.2 160 1 159.8 0.521 1.921

ME-YW 909 ME_YW_909 Delta sands dug 9.5 210 1 207.8 6.768 0.148

ME-YW 963 ME_YW_963 Delta sands dug 11 89 1 86.4 0.521 1.921

ME-YW 965 ME_YW_965 Delta sands dug 10 210 1 205.5 0.521 1.921

ME-YW 966 ME_YW_966 Delta sands dug 9 79 1 73.9 0.521 1.921

ME-YW 967 Genest 33-81 Genest_33_81 Genest 45 211 5 208 6.768 0.148
60 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine

Table 1–1. Groundwater observation information, including well names, well depths, land surface altitude, and variances and weights 

used in the model.—Continued

[ft, feet; NAVD 88, North American Vertical Datum of 1988; σ2, variance]

Well name Model observation 

name

Observation 

group

Well 

depth, 

in ft

Land 

surface 

altitude, 

in ft above 

NAVD 88

Model 

layer

Measured 

water 

level, 

in ft above 

NAVD 88

Total 

variance 

(σ2), 

in ft

Weight, 

1/σ2

ME-YW 971 Genest 34-81 Genest_34_81 Genest 116 219 6 215.2 6.768 0.148

ME-YW 970 Genest 34A-81 Genest_34A Genest 116 218 6 214.6 6.768 0.148

ME-YW 969 Genest 34B Genest_34B Genest 116 218 6 208.1 6.768 0.148

ME-YW 972 Genest 34C Genest_34C Genest 94 221 5 217.4 6.768 0.148

ME-YW 968 Genest 34D Genest_34D Genest 74 219 4 211.6 6.768 0.148

ME-YW 973 Genest 34E Genest_34E Genest 118 246 5 213.2 6.768 0.148

ME-YW 974 Genest 59-81 Genest_59_81 Genest 70 236 4 218.3 6.768 0.148

ME-YW 1020 MWHR 1 KKW_MWHR1 Herrisecket Rd. 55 68 4 28.3 0.521 1.921

ME-YW 1009 KKW MWHR 11 KKW_MWHR11 Herrisecket Rd. 53 51 6 10.8 0.521 1.921

ME-YW 917 KKW-MWHR 12 KKW_MWHR12 Herrisecket Rd. 51 51 5 10.8 0.521 1.921

ME-YW 910 KKW-MWHR 3 KKW_MWHR3 Herrisecket Rd. 69 68. 5 30.6 0.521 1.921

ME-YW 1008 KKW MWHR 4 KKW_MWHR4 Herrisecket Rd. 45 69.5 3 34.7 0.521 1.921

ME-YW 912 KKW-MWHR 6 KKW_MWHR6 Herrisecket Rd. 35 64.9 2 34.3 0.521 1.921

ME-YW 913 KKW-MWHR 7 KKW_MWHR7 Herrisecket Rd. 40 75.7 2 43.4 0.521 1.921

ME-YW 914 KKW-MWHR 8 KKW_MWHR8 Herrisecket Rd. 15 79.2 1 68.1 0.521 1.921

ME-YW 926 KKW-DPMR 1 KKW_DPMR1 Merriland 11 19.8 1 19.1 0.521 1.921

ME-YW 923 KKW-DPMR 3 KKW_DPMR3 Merriland 12 38.2 1 34.9 0.521 1.921

ME-YW 925 KKW-MWMR 1 KKW_MWMR1 Merriland 108 22.4 6 -15.2 0.521 1.921

ME-YW 921 KKW-MWMR 10 KKW_MWMR10 Merriland 73 72.7 6 15.5 0.521 1.921

ME-YW 929 KKW-MWMR 11 KKW_MWMR11 Merriland 66 31.2 5 -3.7 0.521 1.921

ME-YW 1006 KKW MWMR 13 KKW_MWMR13 Merriland 53 34.3 4 18.8 0.521 1.921

ME-YW 931 KKW-MWMR 14 KKW_MWMR14 Merriland 73 17.3 4 -6.6 0.521 1.921

ME-YW 928 KKW-MWMR 15 KKW_MWMR15 Merriland 42 39.8 5 17.2 0.521 1.921

ME-YW 927 KKW-MWMR 16 KKW_MWMR16 Merriland 45 30 6 17.6 0.521 1.921

ME-YW 1007 KKW MWMR 18 KKW_MWMR18 Merriland 100 31 4 -16.8 0.521 1.921

ME-YW 932 KKW-MWMR 5 KKW_MWMR5 Merriland 197 40.1 5 -9.4 0.521 1.921

ME-YW 924 KKW-MWMR 6 KKW_MWMR6 Merriland 134 33.7 6 -13.4 0.521 1.921

ME-YW 930 KKW-MWMR 8 KKW_MWMR8 Merriland 70 38.2 5 -5.7 0.521 1.921

ME-YW 922 KKW-MWMR 9 KKW_MWMR9 Merriland 91 53.1 4 -5 0.521 1.921

ME-YW 980 SWD Eagle 1 SWD_Eagle_1 Sanford 35 227 3 221.6 6.768 0.148

ME-YW 981 SWD Eagle 2 SWD_Eagle_2 Sanford 65 227 4 187.3 6.768 0.148

ME-YW 977 SWD Eagle #6 SWD_Eagle_6 Sanford 91 226 4 205.4 6.768 0.148

ME-YW 978 SWD Eagle #6a SWD_Eagle_6a Sanford 68 227 4 210.6 6.768 0.148

ME-YW 979 SWD Eagle #7 SWD_Eagle_7 Sanford 233 3 231.2 6.768 0.148

ME-YW 975 SWD IDC M1 SWD_IDC_M1 Sanford 130 259 6 226.8 6.768 0.148

ME-YW 976 SWD IDC M4 SWD_IDC_M4 Sanford 93 250 6 225.4 6.768 0.148

ME-YW 982 SWD ND-1 SWD_ND_1 Sanford 65 250 5 237.6 6.768 0.148

ME-YW 983 SWD ND-4 SWD_ND_4 Sanford 50 251 4 237 6.768 0.148

ME-YW 984 SWD ND GP SWD_ND_GP Sanford 65 250 5 237.6 6.768 0.148
Appendix 1 61

Table 1–1. Groundwater observation information, including well names, well depths, land surface altitude, and variances and weights 

used in the model.—Continued

[ft, feet; NAVD 88, North American Vertical Datum of 1988; σ2, variance]

Well name Model observation 

name

Observation 

group

Well 

depth, 

in ft

Land 

surface 

altitude, 

in ft above 

NAVD 88

Model 

layer

Measured 

water 

level, 

in ft above 

NAVD 88

Total 

variance 

(σ2), 

in ft

Weight, 

1/σ2

ME-YW 1010 DEP MW03-02 DEP_MW03_02 Sanford-Cyro 25 232 1 226.2 6.768 0.148

ME-YW 1011 DEP MW-101A DEP_MW101A Sanford-Cyro 19 248.5 1 232.8 6.768 0.148

ME-YW 1012 DEP MW-104A DEP_MW104A Sanford-Cyro 20 242 1 230.6 6.768 0.148

ME-YW 1013 DEP MW-104BR DEP_MW104BR Sanford-Cyro 48 242 5 230.6 6.768 0.148

ME-YW 1014 DEP MW-201A DEP_MW201A Sanford-Cyro 20 244.5 1 232.8 6.768 0.148

ME-YW 1015 DEP MW-204A DEP_MW204A Sanford-Cyro 15 232 1 224.1 6.768 0.148

ME-YW 1016 DEP MW-204B DEP_MW204B Sanford-Cyro 33 232 3 226.2 6.768 0.148

ME-YW 1017 DEP MW-205B DEP_MW205B Sanford-Cyro 38 240.5 4 228.6 6.768 0.148

ME-YW 1018 DEP MW-209A DEP_MW209A Sanford-Cyro 15 232 1 226.3 6.768 0.148

ME-YW 1019 DEP MW-702B DEP_MW702B Sanford-Cyro 13 226 1 223.3 6.768 0.148

ME-YW 1005 DEP Cyro X-2 DEPCyro_X2 Sanford-Cyro 35 250 2 230.4 6.768 0.148

Airport wetland S1 Airport_S SW points 2 228 1 228 6.7 0.15

Airport wetland SW1 Airport_SW SW points 2 237 1 237 6.7 0.15

Estes Lake 11 Estes_Lake_1 SW points 5 213 1 213 6.7 0.15

Estes Lake 21 Estes_Lake_2 SW points 5 213 1 213 6.7 0.15

Estes Lake 31 Estes_Lake_3 SW points 5 213 1 213 6.7 0.15

Merriland headwaters wetland1 Merri_head SW points 2 184 1 184 1 1

Merriland wetland south1 Merri_S_wet SW points 2 165 1 165 6.7 0.15

Ocean wetland1 Ocean_wet SW points 2 13 1 13 1 1

Old Falls Pond1 OldFallsPond SW points 5 5 1 0 0.52 1.9

Perkins Marsh wetland1 Perkins_Msh SW points 2 163 1 163 1 1

Railroad wetland N1 RR_wet_N SW points 2 37 1 37 1 1

Railroad wetland S1 RR_wet_S SW points 2 27 1 27.5 1 1

Sanford wetland 11 Sanford_wet1 SW points 2 249 1 249 6.7 0.15

Saywards Corner wetland1 Saywards_Wet SW points 2 189 1 189 1 1

Till uplands wetland1 Till_up_wet SW points 2 186 1 186 1 1

ME-YW 869 ME_YW_869 Till dug 13.9 142.8 1 138.9 0.521 1.921

ME-YW 877 ME_YW_877 Till dug 18 191.2 1 189.4 0.521 1.921

ME-YW 880 ME_YW_880 Till dug 9 170.8 1 170.8 0.521 1.921

ME-YW 881 ME_YW_881 Till dug 15.1 209.8 1 203.7 0.521 1.921

ME-YW 887 ME_YW_887 Till dug 15 269.8 7 265.1 0.521 1.921

ME-YW 899 ME_YW_899 Till dug 17.6 114.5 1 110 0.521 1.921

ME-YW 904 ME_YW_904 Till dug 12.7 175.3 1 169.5 0.521 1.921

ME-YW 964 ME_YW_964 Till dug 7 144.1 1 143.3 0.521 1.921

1

Surface-water and wetland points used as groundwater level observations.

Appendix 2. Dimensionless Scaled 

Sensitivities for Parameters
64 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued [Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity] Observation name Observation group Horizontal K parameters HK_Alluv HK_BurGrav HK_Coarse HK_Delta1 HK_Delta2 HK_Granite HK_L1ROCK HK_MMRock HK_MrnSand HK_PmUndif HK_Presump HK_Special Nestle_MW01 BB-North -1.23 0.00 -0.91 -0.03 -11.11 -0.18 -0.93 0.00 0.00 0.00 -1.76 0.00 Nestle_MW06 BB-North -1.42 0.00 -1.13 -0.04 -14.49 -0.68 -0.89 0.00 0.00 0.00 -1.31 0.00 Nestle_MW13 BB-North -1.37 0.00 -0.95 -0.03 -11.12 -0.91 -1.07 0.00 0.00 0.00 -1.91 0.00 Nestle_MW14 BB-North -2.66 0.00 -0.39 -0.01 -10.69 -0.78 -1.39 0.00 0.00 -0.00 -3.16 0.00 Nestle_MW16 BB-North -6.00 0.00 -0.20 -0.00 -3.49 -0.22 -1.73 0.00 0.00 -0.00 -3.51 0.00 Nestle_MW24 BB-North -1.04 0.00 -0.77 -0.03 -5.06 -0.02 -1.11 0.00 0.00 -0.00 -2.20 0.00 Nestle_MW33 BB-North -2.79 0.00 -0.39 -0.01 -11.28 -0.45 -1.36 0.00 0.00 0.00 -3.09 0.00 Nestle_MW41 BB-North -2.08 0.00 -0.28 -0.01 -5.26 -0.12 -1.76 0.00 0.00 0.00 -4.42 0.00 Nestle_MW44 BB-North -4.27 0.00 -0.32 -0.01 -8.89 -0.26 -1.07 0.00 0.00 -0.00 -2.28 0.00 Nestle_MW45 BB-North -4.43 0.00 -0.25 -0.01 -7.63 -0.36 -1.54 0.00 0.00 -0.00 -3.26 0.00 Nestle_MW46 BB-North -2.77 0.00 -0.55 -0.02 -15.40 -0.32 -1.10 0.00 -0.00 -0.00 -2.23 0.00 Nestle_MW47 BB-North -2.58 0.00 -0.56 -0.02 -12.28 -0.33 -0.74 0.00 0.00 0.00 -1.38 0.00 KKW_MW02 BB-North -1.64 0.00 -1.32 -0.04 -16.99 -0.30 -1.13 0.00 0.00 -0.00 -1.86 0.00 KKW_MW07A BB-North -1.64 0.00 -1.13 -0.04 -15.11 -0.27 -1.22 0.00 0.00 0.00 -2.25 0.00 KKW_MW15 BB-North -7.49 0.00 -0.21 -0.00 -4.65 -0.11 -1.80 0.00 0.00 -0.00 -3.82 0.00 KKW_MW23 BB-North -1.50 0.00 -0.88 -0.03 -11.97 -0.21 -1.23 0.00 0.00 0.00 -2.67 0.00 KKW_MW26 BB-North -1.51 0.00 -1.29 -0.04 -14.76 -0.24 -1.10 0.00 0.00 0.00 -1.90 0.00 KKW_MW30 BB-North -2.17 0.00 -0.62 -0.02 -14.63 -0.26 -1.70 0.00 0.00 0.00 -4.69 0.00 KKW_MW35 BB-North -3.40 0.00 -0.27 -0.01 -7.56 -0.19 -1.49 0.00 0.00 -0.00 -3.53 0.00 KKW_MW48 BB-North -6.72 0.00 -0.47 -0.01 -10.90 -0.34 -0.89 0.00 -0.00 -0.00 -1.89 0.00 TNC_MW202 BB-South -0.24 0.00 -0.44 -0.01 -5.98 -0.38 -0.92 -0.01 0.00 -0.13 -2.71 0.00

TNC_MW204 BB-South -0.16 0.00 -0.05 -0.01 -5.66 -0.30 -0.65 -0.01 0.00 -0.10 -1.96 0.00TNC_MW101 BB-South -0.32 0.00 3.11 -0.01 -4.22 -0.45 -1.54 -0.00 0.00 -0.19 -3.29 0.00TNC_MW105 BB-South -0.31 0.00 0.17 -0.01 -4.75 -0.46 -1.23 -0.01 -0.00 -0.19 -2.62 0.00TNC_MW106 BB-South -0.18 0.00 -0.73 -0.01 -5.12 -0.35 -0.78 -0.01 -0.00 -0.14 -1.94 0.00TNC_MW103 BB-South -0.22 0.00 -1.91 -0.02 -4.55 -1.12 -1.54 -0.00 -0.00 -0.28 -2.64 0.00TNC_MW107 BB-South -0.21 0.00 -2.12 -0.02 -4.63 -0.48 -1.55 -0.00 0.00 -0.28 -2.68 0.00TNC_MW109 BB-South -0.27 0.00 0.59 -0.02 -4.44 -0.43 -1.73 -0.00 -0.00 -0.25 -3.02 0.00TNC_MW110 BB-South -0.31 0.00 0.26 -0.01 -5.31 -0.63 -1.09 -0.01 -0.00 -0.15 -2.97 0.00TNC_MW304 BB-South -0.44 0.00 1.46 -0.01 -5.32 -0.43 -1.21 -0.01 -0.00 -0.14 -3.56 0.00TNC_MW308 BB-South -0.19 0.00 -2.89 -0.02 -4.84 -0.46 -1.21 -0.00 -0.00 -0.26 -2.19 0.00TNC_MW310 BB-South -0.18 0.00 -3.20 -0.02 -4.86 -0.46 -1.17 -0.00 0.00 -0.27 -2.08 0.00TNC_MW401 BB-South -0.23 0.00 -0.92 -0.02 -4.70 -0.46 -1.50 -0.00 -0.00 -0.24 -2.74 0.00TNC_MW410 BB-South -0.23 0.00 -0.83 -0.02 -4.54 -0.46 -1.56 -0.00 -0.00 -0.25 -2.80 0.00TNC_MW422 BB-South -0.11 0.00 -0.01 -0.00 -13.28 -0.16 -0.63 -0.03 -0.00 -0.05 -9.37 0.00TNC_MW430 BB-South -0.04 0.00 -0.05 -0.00 -6.90 -0.10 -0.23 -0.01 -0.00 -0.02 -2.47 0.00TNC_MW403 BB-South -0.26 0.00 0.37 -0.02 -4.21 -0.43 -1.73 -0.00 0.00 -0.26 -2.93 0.00TNC_MW404 BB-South -0.21 0.00 -1.94 -0.03 -4.43 -0.54 -1.70 -0.00 -0.00 -0.32 -2.80 0.00TNC_MW415 BB-South -0.25 0.00 0.46 -0.02 -4.29 -0.44 -1.73 -0.00 -0.00 -0.25 -3.01 0.00
Appendix 2 65

Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued[Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity]

Observation name Observation 

group

Horizontal K parameters

HK_Alluv HK_BurGrav HK_Coarse HK_Delta1 HK_Delta2 HK_Granite HK_L1ROCK HK_MMRock HK_MrnSand HK_PmUndif HK_Presump HK_Special

TNC_MW425 BB-South -0.32 0.00 0.04 -0.01 -5.08 -0.43 -1.07 -0.01 0.00 -0.16 -2.70 0.00TNC_MW433 BB-South -0.23 0.00 -1.04 -0.01 -4.95 -0.44 -1.14 -0.00 0.00 -0.20 -2.37 0.00TNC_MW440 BB-South -0.21 0.00 -1.93 -0.02 -4.55 -0.47 -1.61 -0.00 -0.00 -0.29 -2.74 0.00TNC_MW315 BB-South -0.20 0.00 -2.82 -0.02 -4.75 -0.48 -1.43 -0.00 -0.00 -0.29 -2.50 0.00ME_YW_870 Bedrock -0.14 0.00 -0.00 0.00 0.13 0.00 -0.97 -0.77 -0.02 -0.30 -1.24 0.00ME_YW_878 Bedrock 0.00 0.00 -0.00 0.00 -0.00 -0.04 -0.07 0.00 -1.26 -0.00 -0.38 0.00ME_YW_882 Bedrock -0.07 0.00 -0.06 -0.28 -3.22 -0.64 -0.45 0.00 0.00 -0.35 -0.09 0.00ME_YW_883 Bedrock -0.00 0.00 0.00 -0.01 -0.00 -0.01 -0.48 0.00 -0.85 -0.07 -0.03 0.00ME_YW_888 Bedrock -0.00 0.00 -0.00 -0.00 0.00 -1.65 -0.76 0.00 -0.00 -0.47 -0.00 -12.69ME_YW_891 Bedrock -0.00 -0.34 0.00 0.00 -0.00 0.00 -0.00 0.03 -0.32 0.00 -0.02 0.00ME_YW_894 Bedrock -0.58 0.03 0.00 0.00 0.00 0.00 -0.23 -0.49 -2.29 0.00 -0.00 0.00ME_YW_896 Bedrock -0.02 -0.00 0.00 0.00 0.00 0.02 -0.56 0.53 -0.34 0.00 -0.32 0.00ME_YW_897 Bedrock -0.00 -0.00 0.00 0.00 -0.01 -0.17 -3.11 -0.92 -0.97 0.00 -0.72 0.00ME_YW_901 Bedrock -0.01 0.00 -0.03 -0.00 -1.81 -0.12 -0.11 -0.01 -0.01 -0.00 -0.33 0.00ME_YW_871 Coastal sands dug -0.02 -1.07 0.00 0.00 -0.15 0.01 -0.04 -0.07 -11.37 -0.00 -4.39 0.00ME_YW_872 Coastal sands dug -0.02 -0.91 0.00 0.00 -0.16 0.01 -0.03 -0.06 -11.52 -0.00 -3.80 0.00ME_YW_873 Coastal sands dug -0.00 -0.61 0.00 0.00 -0.02 0.01 0.00 -0.04 -6.67 -0.00 -0.48 0.00ME_YW_890 Coastal sands dug -0.00 -0.36 0.00 0.00 -0.00 0.00 -0.00 0.00 -2.18 0.00 -0.02 0.00ME_YW_892 Coastal sands dug -0.01 -0.86 0.00 0.00 -0.00 0.00 -0.10 -0.02 -15.60 0.00 -0.03 0.00ME_YW_893 Coastal sands dug -3.45 0.05 0.00 0.00 0.00 0.00 -0.65 -0.32 -11.83 0.00 -0.00 0.00ME_YW_906 Coastal sands dug -0.01 -1.14 0.00 0.00 -0.00 0.00 -0.00 0.00 -3.12 0.00 -0.06 0.00ME_YW_874 Delta sands dug -4.64 0.00 0.00 0.00 -20.77 -0.01 -6.14 -0.93 -0.53 -1.72 -8.40 0.00ME_YW_875 Delta sands dug -0.15 0.00 -0.00 0.00 -0.41 -0.00 -0.97 -0.27 -0.19 -10.71 -1.96 0.00ME_YW_876 Delta sands dug -0.48 0.00 -1.18 -0.01 -19.90 -0.18 -0.37 0.00 -0.00 -0.00 -0.12 0.00ME_YW_884 Delta sands dug -0.60 0.00 -0.36 -0.38 -25.95 -0.69 -1.73 0.00 0.00 -0.43 -0.70 0.00ME_YW_885 Delta sands dug -0.12 0.00 -0.07 -1.13 -9.07 -0.02 -0.39 0.00 0.00 -0.06 -0.05 0.00ME_YW_886 Delta sands dug -0.01 0.00 -0.05 -6.85 -0.41 -0.12 -0.02 0.00 0.00 -4.70 -0.03 0.00ME_YW_900 Delta sands dug -0.01 0.00 -0.08 0.00 -10.54 -0.85 -1.43 -0.01 -0.04 -0.01 -1.51 0.00ME_YW_902 Delta sands dug -0.01 0.00 -0.71 -0.01 -2.38 0.02 -0.02 0.00 0.00 0.00 -0.00 0.00ME_YW_903 Delta sands dug -0.29 0.00 0.00 0.00 -2.26 0.00 -0.19 0.01 -4.37 -1.24 -0.15 0.00ME_YW_905 Delta sands dug -0.00 0.00 -0.40 -0.00 -0.98 -0.02 -0.02 0.00 0.00 0.00 -0.00 0.00ME_YW_907 Delta sands dug -0.53 0.00 -0.02 0.00 -7.26 0.40 -0.74 -0.16 -0.16 -0.00 -5.02 0.00ME_YW_908 Delta sands dug -0.05 0.00 -0.10 -0.00 -4.01 -0.01 -0.06 -0.05 -0.02 -0.01 -1.76 0.00ME_YW_909 Delta sands dug -0.10 0.00 -0.23 -0.01 -6.29 -0.16 -0.14 0.00 0.00 -0.00 -0.02 0.00ME_YW_963 Delta sands dug -0.07 -0.03 0.00 0.00 -1.32 0.00 0.02 0.05 -2.62 -0.00 -0.65 0.00ME_YW_965 Delta sands dug -0.02 0.00 -0.16 -0.02 -4.76 0.01 -0.09 0.00 0.00 -0.00 -0.01 0.00ME_YW_966 Delta sands dug -0.19 0.00 0.00 0.00 0.01 0.00 -0.14 0.05 -0.03 -0.00 -2.50 0.00
66 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued [Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity] Observation name Observation group Horizontal K parameters HK_Alluv HK_BurGrav HK_Coarse HK_Delta1 HK_Delta2 HK_Granite HK_L1ROCK HK_MMRock HK_MrnSand HK_PmUndif HK_Presump HK_Special ME_YW_869 Till dug -1.59 -0.00 0.00 0.00 -6.75 -0.04 -1.99 -0.61 -0.32 -0.29 -0.45 0.00 ME_YW_877 Till dug 0.00 0.00 0.00 -0.03 0.00 -0.07 -0.14 0.00 -0.00 -1.69 0.00 0.01 ME_YW_880 Till dug -0.02 0.00 -0.00 -0.01 -0.01 0.15 -1.27 0.00 -0.01 -0.01 -0.13 0.00 ME_YW_881 Till dug -0.00 0.00 -0.03 -0.14 -0.10 -0.25 -0.29 0.00 -0.00 -2.63 -0.02 0.00 ME_YW_899 Till dug 0.00 0.00 -0.00 0.00 -0.00 0.05 0.10 0.00 0.00 0.00 -0.06 0.00 ME_YW_904 Till dug -0.07 -0.00 -0.00 0.00 -0.03 -0.05 -5.05 -1.64 -7.01 -0.00 -0.76 0.00 ME_YW_964 Till dug -0.00 -0.00 0.00 0.00 -0.01 -0.60 -2.03 -0.00 -0.33 0.00 -2.27 0.00 Genest_33_81 Genest -0.00 0.00 -0.03 0.05 -0.88 0.00 0.00 0.00 0.00 -0.00 -0.00 0.00 Genest_34D Genest -0.00 0.00 -0.03 -0.02 -0.88 0.00 -0.01 0.00 0.00 -0.00 -0.00 0.00 Genest_34B Genest -0.00 0.00 -0.03 -0.06 -0.87 0.00 -0.01 0.00 0.00 -0.00 -0.00 0.00 Genest_34A Genest -0.00 0.00 -0.03 -0.07 -0.86 0.00 -0.01 0.00 0.00 -0.00 -0.00 0.00 Genest_34_81 Genest -0.00 0.00 -0.03 -0.07 -0.86 0.00 -0.01 0.00 0.00 -0.00 -0.00 0.00 Genest_34C Genest -0.00 0.00 -0.03 -0.08 -0.83 0.00 -0.01 0.00 0.00 -0.00 -0.00 0.00 Genest_34E Genest -0.00 0.00 -0.03 -0.12 -0.78 0.00 -0.01 0.00 0.00 -0.00 -0.00 0.00 Genest_59_81 Genest -0.00 0.00 -0.02 -0.16 -0.81 0.00 -0.01 0.00 0.00 -0.00 -0.00 0.00 KKW_MWHR4 Herrisecket Rd. -0.06 -0.48 0.00 0.00 -0.00 -0.00 0.15 -0.05 -2.64 0.00 -0.54 0.00 KKW_MWHR11 Herrisecket Rd. -0.03 4.06 0.00 0.00 -0.00 -0.00 0.04 0.21 0.12 0.00 -0.41 0.00 KKW_MWHR1 Herrisecket Rd. -0.06 -0.48 0.00 0.00 -0.00 -0.00 0.14 -0.04 -2.87 0.00 -0.54 0.00 KKW_MWHR3 Herrisecket Rd. -0.06 -0.49 0.00 0.00 -0.00 -0.00 0.14 -0.04 -2.90 0.00 -0.54 0.00 KKW_MWHR6 Herrisecket Rd. -0.06 -0.48 0.00 0.00 -0.00 -0.00 0.13 -0.05 -1.89 0.00 -0.57 0.00

KKW_MWHR7 Herrisecket Rd. -0.02 -0.64 0.00 0.00 -0.00 -0.00 -0.36 -0.23 -16.85 0.00 -3.11 0.00KKW_MWHR8 Herrisecket Rd. -0.05 -0.57 0.00 0.00 -0.00 -0.00 0.05 -0.11 -8.07 0.00 -0.91 0.00KKW_MWHR12 Herrisecket Rd. -0.03 5.94 0.00 0.00 -0.00 0.00 0.04 0.04 0.19 0.00 -0.40 0.00KKW_MWMR13 Merriland -0.13 4.11 0.00 0.00 -0.00 0.00 0.05 0.04 -0.62 0.00 -0.03 0.00KKW_MWMR18 Merriland -0.12 15.73 0.00 0.00 -0.00 0.00 0.08 0.06 -0.53 0.00 -0.03 0.00KKW_MWMR10 Merriland -0.56 -7.92 0.00 0.00 0.00 0.00 0.11 0.33 -1.35 0.00 -0.17 0.00KKW_MWMR9 Merriland -0.15 5.23 0.00 0.00 -0.00 0.00 0.08 0.06 -0.67 0.00 -0.04 0.00KKW_DPMR3 Merriland -0.49 1.91 0.00 0.00 -0.00 0.00 0.04 0.02 -0.36 0.00 -0.04 0.00KKW_MWMR6 Merriland -0.11 17.03 0.00 0.00 -0.00 0.00 0.07 0.23 -0.52 0.00 -0.03 0.00KKW_MWMR1 Merriland -0.11 18.75 0.00 0.00 0.00 0.00 0.07 0.34 -0.51 0.00 -0.03 0.00KKW_DPMR1 Merriland -0.97 0.87 0.00 0.00 0.00 0.00 0.01 0.01 -0.07 0.00 -0.01 0.00KKW_MWMR16 Merriland -2.45 0.09 0.00 0.00 0.00 0.00 -0.04 -0.38 -5.88 0.00 -0.00 0.00KKW_MWMR15 Merriland -2.04 0.03 0.00 0.00 0.00 0.00 -0.81 -0.17 -5.14 0.00 -0.00 0.00KKW_MWMR11 Merriland -0.06 9.29 0.00 0.00 -0.00 0.00 0.09 0.06 -0.36 0.00 -0.03 0.00KKW_MWMR8 Merriland -0.10 6.95 0.00 0.00 -0.00 0.00 0.12 0.08 -0.55 0.00 -0.04 0.00KKW_MWMR14 Merriland -0.08 3.79 0.00 0.00 -0.00 0.00 0.03 0.03 -0.35 0.00 -0.02 0.00KKW_MWMR5 Merriland -0.12 10.78 0.00 0.00 -0.00 0.00 0.07 0.06 -0.55 0.00 -0.03 0.00
Appendix 2 67

Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued[Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity]

Observation name Observation 

group

Horizontal K parameters

HK_Alluv HK_BurGrav HK_Coarse HK_Delta1 HK_Delta2 HK_Granite HK_L1ROCK HK_MMRock HK_MrnSand HK_PmUndif HK_Presump HK_Special

DEPCyro_X2 Sanford-Cyro -0.00 0.00 -0.30 -0.45 -0.74 -0.03 -0.03 0.00 0.00 -0.00 -0.00 0.00DEP_MW03_02 Sanford-Cyro -0.00 0.00 -0.02 -0.02 -0.12 -0.00 -0.00 0.00 0.00 0.00 0.00 0.00DEP_MW101A Sanford-Cyro -0.00 0.00 -0.09 -0.11 -2.16 -0.08 -0.10 0.00 0.00 0.00 -0.00 0.00DEP_MW104A Sanford-Cyro -0.00 0.00 -0.07 -0.08 -0.80 -0.02 -0.02 0.00 0.00 0.00 -0.00 0.00DEP_MW104BR Sanford-Cyro -0.00 0.00 -0.08 -0.09 -0.60 -0.01 -0.01 0.00 0.00 0.00 -0.00 0.00DEP_MW201A Sanford-Cyro -0.00 0.00 -0.13 -0.15 -1.40 -0.04 -0.06 0.00 0.00 0.00 -0.00 0.00DEP_MW204A Sanford-Cyro -0.00 0.00 -0.04 -0.04 -0.20 -0.00 -0.00 0.00 0.00 0.00 -0.00 0.00DEP_MW204B Sanford-Cyro -0.00 0.00 -0.04 -0.05 -0.22 -0.00 -0.00 0.00 0.00 0.00 -0.00 0.00DEP_MW205B Sanford-Cyro -0.00 0.00 -0.08 -0.09 -0.47 -0.01 -0.01 0.00 0.00 0.00 -0.00 0.00DEP_MW209A Sanford-Cyro -0.00 0.00 -0.09 -0.07 -0.37 -0.01 -0.01 0.00 0.00 0.00 -0.00 0.00DEP_MW702B Sanford-Cyro 0.00 0.00 -0.01 -0.01 -0.07 -0.00 -0.00 0.00 0.00 0.00 0.00 0.00SWD_IDC_M1 Sanford -0.00 0.00 -0.43 -0.08 -0.67 0.01 -0.03 0.00 0.00 0.00 -0.00 0.00SWD_IDC_M4 Sanford -0.00 0.00 -0.51 -0.30 -0.76 -0.04 -0.03 0.00 0.00 0.00 -0.00 0.00SWD_Eagle_6 Sanford -0.00 0.00 -0.30 0.16 -0.50 -0.01 -0.01 0.00 0.00 0.00 -0.00 0.00SWD_Eagle_6a Sanford -0.00 0.00 -0.31 0.15 -0.51 -0.01 -0.01 0.00 0.00 0.00 -0.00 0.00SWD_Eagle_7 Sanford -0.00 0.00 -0.25 0.42 -0.43 -0.01 -0.01 0.00 0.00 0.00 -0.00 0.00SWD_Eagle_1 Sanford -0.00 0.00 -0.21 0.37 -0.37 -0.01 -0.01 0.00 0.00 0.00 -0.00 0.00SWD_Eagle_2 Sanford -0.00 0.00 -0.31 0.15 -0.51 -0.01 -0.01 0.00 0.00 0.00 -0.00 0.00SWD_ND_1 Sanford -0.00 0.00 -0.00 -0.23 -0.45 -0.02 -0.01 0.00 0.00 0.00 0.00 0.00SWD_ND_4 Sanford 0.00 0.00 -0.00 -0.23 -0.46 -0.02 -0.01 0.00 0.00 0.00 0.00 0.00SWD_ND_GP Sanford 0.00 0.00 -0.00 -0.23 -0.45 -0.02 -0.01 0.00 0.00 0.00 0.00 0.00Sanford_wet1 SW points -0.00 0.00 -0.00 -0.94 -1.07 -0.09 -0.09 0.00 0.00 0.00 0.00 0.00Saywards_Wet SW points -0.03 0.00 -0.02 -0.13 -0.45 -0.02 -0.04 0.00 0.00 -0.30 -0.02 0.00Airport_S SW points -0.00 0.00 -0.02 -0.02 -0.39 0.00 -0.00 0.00 0.00 -0.00 0.00 0.00Airport_SW SW points -0.00 0.00 -0.01 -0.01 -0.76 -0.01 -0.02 0.00 0.00 -0.00 -0.00 0.00Merri_head SW points -0.00 0.00 -0.00 -0.10 0.44 -0.02 -0.00 0.00 0.00 -0.21 -0.00 -0.00Till_up_wet SW points -0.02 0.00 -0.53 -0.02 -1.58 -0.60 -1.06 -0.00 -0.01 -0.37 -0.35 0.00Merri_S_wet SW points 0.00 0.00 0.00 -0.05 0.00 0.00 -0.01 0.00 -0.02 0.05 -0.00 0.00Ocean_wet SW points -0.01 -0.00 0.00 0.00 0.00 0.00 0.02 -0.00 0.00 0.00 -0.00 0.00RR_wet_N SW points -0.01 -0.60 0.00 0.00 0.00 0.00 -0.00 0.01 -1.11 0.00 -0.04 0.00RR_wet_S SW points -0.04 -0.66 0.00 0.00 -0.00 0.00 -0.01 -0.02 -5.72 0.00 -0.03 0.00Perkins_Msh SW points -0.01 0.00 0.05 -0.00 0.05 0.01 -0.00 0.00 0.00 -0.00 -0.00 0.00Estes_Lake_1 SW points 0.00 0.00 0.00 -0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Estes_Lake_2 SW points 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Estes_Lake_3 SW points 0.00 0.00 -0.00 0.00 -0.00 -0.00 -0.00 0.00 0.00 0.00 0.00 0.00OldFallsPond SW points 0.00 0.00 0.00 0.00 -0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
68 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued [Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity] Observation name Observation group Horizontal K parameters HK_Alluv HK_BurGrav HK_Coarse HK_Delta1 HK_Delta2 HK_Granite HK_L1ROCK HK_MMRock HK_MrnSand HK_PmUndif HK_Presump HK_Special Merri2_Str_1 Baseflows 0.01 0.00 0.04 0.03 0.07 0.00 0.05 0.01 0.06 -0.04 0.03 0.00 Merri1_Str_1 Baseflows -0.00 0.13 0.00 0.00 0.00 -0.00 -0.00 -0.01 -0.05 0.00 0.03 0.00 Perkins_st_1 Baseflows 0.05 0.00 0.39 0.11 -0.28 0.02 0.03 -0.00 0.00 0.00 0.03 0.00 Cold_seeps_1 Baseflows 0.42 0.00 0.23 0.00 0.36 0.15 0.08 0.01 0.00 0.03 0.32 0.00 BB7_Str_1 Baseflows 0.01 0.00 0.59 0.15 0.56 0.04 0.03 0.00 0.00 0.00 0.00 0.00 BB6_Str_1 Baseflows 0.01 0.00 0.09 0.33 0.98 -0.00 0.04 0.00 0.00 0.01 0.00 0.00 BB5_Seeps_1 Baseflows 0.03 0.00 0.11 0.03 0.36 0.02 0.19 0.00 0.00 -0.00 0.20 0.00 BB4_Seeps_1 Baseflows 0.01 0.00 0.01 0.00 -0.00 -0.00 0.01 0.00 0.00 0.00 0.20 0.00 BB4_Str_1 Baseflows 0.03 0.00 0.50 0.00 0.65 0.10 0.19 0.00 0.00 0.05 0.53 0.00 BB3_Seeps_1 Baseflows -0.42 0.00 -0.22 0.00 -0.80 0.00 0.24 -0.00 0.06 0.04 0.60 0.00 BB2_Seeps_1 Baseflows 0.39 0.00 0.00 0.00 -0.46 0.00 0.28 0.02 -0.05 0.07 0.23 0.00 BB2_Str_1 Baseflows 0.03 0.00 0.08 0.00 0.34 0.05 0.21 0.04 -0.01 0.01 0.28 0.00 BB1_Seeps_1 Baseflows 0.01 0.52 0.00 0.00 0.00 0.00 -0.11 -0.01 0.45 0.00 0.72 0.00 BB8_Str_1 Baseflows 0.01 0.06 0.00 0.00 0.00 -0.00 0.04 0.03 0.59 0.00 0.04 0.00 Day_Seeps_1 Baseflows 0.12 0.00 0.00 0.00 1.21 0.01 0.12 0.05 0.13 0.06 0.07 0.00 Day_Str_1 Baseflows 0.17 0.00 0.00 0.00 0.70 0.00 0.10 0.03 0.75 -0.15 0.34 0.00 Merri2_Riv_1 Baseflows 0.01 -0.00 0.00 0.00 0.00 -0.18 -0.53 -0.06 0.10 0.00 -0.18 0.00 Merri1_Riv_1 Baseflows -0.10 -0.40 0.00 0.00 0.00 -0.00 0.00 0.00 0.01 0.00 -0.02 0.00 BB5_Riv_1 Baseflows -0.01 0.00 -1.13 0.04 -1.68 -0.06 -0.38 0.00 0.00 0.00 -0.37 0.00 BB3_Riv_1 Baseflows 0.21 0.00 -1.20 0.00 -0.41 -0.26 -1.50 -0.05 0.02 0.01 -4.59 0.00 BB2_Riv_1 Baseflows -0.18 0.00 0.00 0.00 -0.06 0.00 -0.13 -0.02 -0.71 0.00 -0.08 0.00 BB1_Riv_1 Baseflows 0.01 1.22 0.00 0.00 0.01 -0.00 -0.06 -0.04 -0.33 0.00 -0.84 0.00
Appendix 2 69

Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued[Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity]

Observation name Observation group Recharge parameters HK_Till HK_wetland HK_ShearZn HK_ClayEXP Moraines Sandy_1 Till Wetlands Bedrock Alluv_Urb Sandy_2 RCH_Xtra

Nestle_MW01 BB-North -0.00 -0.02 -0.00 -0.48 0.00 25.94 0.02 0.08 0.02 0.03 0.84 0.82Nestle_MW06 BB-North -0.01 -0.03 -0.00 -0.55 0.00 26.89 0.02 0.13 0.03 0.03 1.40 0.85Nestle_MW13 BB-North -0.01 -0.03 -0.00 -0.88 0.00 24.47 0.04 0.09 0.02 0.03 1.00 0.75Nestle_MW14 BB-North -0.00 -0.03 -0.00 -0.92 0.00 29.50 0.02 0.04 0.01 0.06 0.59 0.98Nestle_MW16 BB-North -0.00 -0.03 0.00 -0.46 0.00 26.88 0.01 0.02 0.01 0.12 0.30 0.49Nestle_MW24 BB-North -0.01 -0.02 -0.00 -0.59 0.00 18.92 0.03 0.06 0.02 0.03 0.67 0.47Nestle_MW33 BB-North -0.00 -0.02 0.00 -0.77 0.00 30.20 0.02 0.04 0.01 0.06 0.57 1.02Nestle_MW41 BB-North -0.00 -0.02 -0.00 -1.20 0.00 26.48 0.03 0.03 0.01 0.07 0.47 0.76Nestle_MW44 BB-North -0.00 -0.03 -0.00 -0.44 0.00 28.54 0.01 0.03 0.01 0.07 0.51 0.88Nestle_MW45 BB-North -0.00 -0.03 0.00 -0.56 0.00 28.74 0.01 0.02 0.01 0.09 0.39 0.78Nestle_MW46 BB-North -0.00 -0.03 -0.00 -0.56 0.00 34.58 0.01 0.06 0.02 0.04 0.79 1.49Nestle_MW47 BB-North -0.00 -0.04 0.00 -0.39 0.00 28.37 0.01 0.07 0.02 0.03 0.97 1.05KKW_MW02 BB-North -0.01 -0.03 -0.00 -0.54 0.00 35.16 0.03 0.13 0.03 0.04 1.33 1.31KKW_MW07A BB-North -0.01 -0.03 -0.00 -0.63 0.00 32.44 0.03 0.10 0.03 0.04 1.09 1.09KKW_MW15 BB-North -0.00 -0.03 0.00 -0.49 0.00 32.98 0.01 0.02 0.01 0.15 0.34 0.62KKW_MW23 BB-North -0.00 -0.02 -0.00 -0.71 0.00 29.62 0.02 0.08 0.02 0.04 0.85 0.91KKW_MW26 BB-North -0.01 -0.03 -0.00 -0.54 0.00 32.58 0.03 0.11 0.03 0.04 1.18 1.08KKW_MW30 BB-North -0.00 -0.02 -0.00 -1.10 0.00 39.00 0.02 0.06 0.02 0.05 0.75 1.19KKW_MW35 BB-North -0.00 -0.02 -0.00 -0.62 0.00 32.25 0.01 0.03 0.01 0.07 0.44 0.99KKW_MW48 BB-North -0.00 -0.04 -0.00 -0.46 0.00 35.89 0.01 0.05 0.01 0.05 0.83 1.10TNC_MW202 BB-South -0.09 -0.17 0.00 -0.23 0.04 18.28 0.52 0.16 0.09 0.05 3.67 0.98TNC_MW204 BB-South -0.07 -0.15 0.00 -0.17 0.03 14.13 0.41 0.12 0.07 0.04 3.34 0.72TNC_MW101 BB-South -0.12 -0.19 -0.00 -0.20 0.04 19.31 0.79 0.22 0.14 0.08 3.91 0.83TNC_MW105 BB-South -0.12 -0.21 -0.00 -0.18 0.05 19.52 0.78 0.22 0.14 0.07 4.25 0.94TNC_MW106 BB-South -0.10 -0.20 -0.00 -0.16 0.04 14.87 0.56 0.17 0.09 0.04 4.08 0.74TNC_MW103 BB-South -0.17 -0.25 -0.00 -0.22 0.06 19.23 1.18 0.32 0.21 0.05 5.08 0.73TNC_MW107 BB-South -0.17 -0.25 -0.00 -0.17 0.06 20.46 1.21 0.32 0.22 0.05 5.10 0.82TNC_MW109 BB-South -0.15 -0.22 -0.00 -0.17 0.05 20.82 1.07 0.28 0.20 0.06 4.52 0.86TNC_MW110 BB-South -0.10 -0.18 -0.00 -0.26 0.04 19.11 0.59 0.17 0.10 0.07 3.75 0.96TNC_MW304 BB-South -0.09 -0.17 -0.00 -0.28 0.04 21.67 0.57 0.17 0.10 0.08 3.52 1.12TNC_MW308 BB-South -0.16 -0.27 -0.00 -0.15 0.06 18.31 1.07 0.30 0.18 0.05 5.21 0.80TNC_MW310 BB-South -0.16 -0.28 -0.00 -0.15 0.07 17.87 1.10 0.31 0.19 0.04 5.35 0.76TNC_MW401 BB-South -0.15 -0.24 -0.00 -0.17 0.06 20.79 1.03 0.28 0.18 0.06 4.72 0.96TNC_MW410 BB-South -0.15 -0.23 -0.00 -0.17 0.05 20.21 1.06 0.29 0.19 0.06 4.72 0.87TNC_MW422 BB-South -0.04 -0.07 0.00 -0.83 0.01 32.69 0.20 0.06 0.03 0.03 1.78 1.76TNC_MW430 BB-South -0.02 -0.04 0.00 -0.22 0.01 13.73 0.10 0.03 0.02 0.01 1.60 0.60TNC_MW403 BB-South -0.16 -0.22 -0.00 -0.17 0.05 20.42 1.14 0.30 0.21 0.05 4.59 0.73TNC_MW404 BB-South -0.18 -0.24 -0.00 -0.19 0.06 20.67 1.36 0.35 0.25 0.05 5.23 0.67TNC_MW415 BB-South -0.15 -0.22 -0.00 -0.17 0.05 20.20 1.08 0.29 0.20 0.06 4.55 0.81
70 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued [Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity] Observation name Observation group Recharge parameters HK_Till HK_wetland HK_ShearZn HK_ClayEXP Moraines Sandy_1 Till Wetlands Bedrock Alluv_Urb Sandy_2 RCH_Xtra TNC_MW425 BB-South -0.10 -0.19 -0.00 -0.21 0.04 19.24 0.64 0.19 0.11 0.06 3.94 0.95 TNC_MW433 BB-South -0.13 -0.23 -0.00 -0.17 0.05 18.97 0.81 0.23 0.14 0.06 4.51 0.95 TNC_MW440 BB-South -0.17 -0.24 -0.00 -0.17 0.06 21.22 1.26 0.33 0.23 0.05 5.12 0.81 TNC_MW315 BB-South -0.17 -0.26 -0.00 -0.17 0.06 19.99 1.21 0.33 0.22 0.05 5.25 0.82 ME_YW_870 Bedrock -0.00 -0.00 0.00 -0.01 0.00 1.50 0.41 0.00 0.00 0.50 1.61 0.05 ME_YW_878 Bedrock -0.06 -0.37 0.00 -0.00 0.21 0.00 0.40 0.10 0.34 0.00 1.89 0.00 ME_YW_882 Bedrock -0.76 -0.23 -0.12 -0.36 0.00 5.16 1.62 0.09 0.34 0.00 0.32 0.00 ME_YW_883 Bedrock -0.71 -0.29 0.00 0.00 0.00 0.00 0.97 0.28 0.43 0.00 2.01 0.00 ME_YW_888 Bedrock -0.84 -0.07 0.02 -0.02 0.00 0.08 1.72 0.14 15.58 0.00 0.04 0.00 ME_YW_891 Bedrock -0.00 -0.00 0.00 0.03 0.00 0.47 0.01 0.02 0.00 0.00 0.40 0.00 ME_YW_894 Bedrock -0.00 -0.01 0.00 -0.95 0.00 4.12 0.00 0.03 0.00 0.01 0.01 0.00 ME_YW_896 Bedrock -0.56 0.00 0.00 -0.01 0.00 0.31 1.55 0.00 0.10 0.00 0.11 0.00 ME_YW_897 Bedrock -2.80 -0.01 0.00 -0.03 0.01 0.52 6.33 0.02 0.13 0.33 1.91 0.00 ME_YW_901 Bedrock -0.57 -0.09 0.00 -0.06 0.06 3.38 0.36 0.02 0.06 0.02 0.81 0.00 ME_YW_871 Coastal sands dug -0.01 -0.00 0.00 -1.32 0.00 7.65 3.51 0.59 0.12 0.72 11.31 0.00 ME_YW_872 Coastal sands dug -0.00 -0.00 0.00 -1.23 0.00 7.67 2.98 0.50 0.13 0.58 11.24 0.00 ME_YW_873 Coastal sands dug -0.00 -0.00 0.00 -0.41 0.00 0.76 0.59 0.27 0.10 0.10 9.31 0.00 ME_YW_890 Coastal sands dug -0.00 -0.02 0.00 -0.03 0.00 5.57 0.02 0.03 0.00 0.00 0.43 0.00 ME_YW_892 Coastal sands dug -0.00 -0.11 0.00 -0.14 0.00 22.80 0.20 0.07 0.00 0.01 2.11 0.00 ME_YW_893 Coastal sands dug -0.00 -0.03 0.00 -4.51 0.00 24.84 0.00 0.14 0.00 0.05 0.04 0.00 ME_YW_906 Coastal sands dug -0.00 -0.01 0.00 -0.08 0.00 0.28 0.10 0.13 0.01 0.01 7.09 0.00

ME_YW_874 Delta sands dug -0.54 -0.13 0.00 -1.40 0.00 45.89 1.08 0.58 0.13 1.31 2.44 0.00ME_YW_875 Delta sands dug -0.01 -0.00 0.00 -0.07 0.00 6.99 0.39 0.03 0.00 0.68 12.84 0.20ME_YW_876 Delta sands dug -0.01 -1.47 0.00 -0.31 0.00 22.59 0.00 0.09 0.02 0.01 10.39 0.03ME_YW_884 Delta sands dug -1.02 -0.67 -0.20 -0.50 0.00 36.66 2.27 0.16 0.26 0.02 1.30 0.02ME_YW_885 Delta sands dug -0.06 -0.28 -0.22 0.32 0.00 13.81 0.14 0.10 0.02 0.00 1.35 0.00ME_YW_886 Delta sands dug 0.09 -0.42 0.05 -0.06 0.00 12.55 2.01 0.52 0.70 0.00 0.24 0.00ME_YW_900 Delta sands dug -5.99 -0.32 0.00 -0.33 0.37 23.43 2.80 0.10 0.57 0.10 1.52 0.01ME_YW_902 Delta sands dug -0.00 -0.54 0.00 -0.09 0.00 0.42 0.02 0.03 0.00 0.00 5.11 0.00ME_YW_903 Delta sands dug -0.01 -0.00 0.00 -0.06 0.00 13.03 0.02 0.01 0.00 0.03 0.99 0.02ME_YW_905 Delta sands dug -0.00 -0.02 0.00 -0.08 0.00 0.21 0.02 0.03 0.00 0.00 1.88 0.00ME_YW_907 Delta sands dug -0.35 -0.03 0.00 0.01 0.02 2.19 0.71 0.01 0.07 0.16 19.45 0.01ME_YW_908 Delta sands dug -0.24 -0.10 0.00 -0.10 0.03 3.06 0.24 0.02 0.03 0.07 11.00 0.03ME_YW_909 Delta sands dug -0.00 -0.21 0.00 -0.10 0.00 3.92 0.00 0.04 0.01 0.00 5.82 0.01ME_YW_963 Delta sands dug -0.01 -0.00 0.00 -0.30 0.00 6.39 0.25 0.02 0.11 0.03 0.41 0.00ME_YW_965 Delta sands dug 0.07 -0.01 -0.02 0.63 0.00 6.33 0.06 0.06 0.00 0.00 0.29 0.00ME_YW_966 Delta sands dug -0.01 0.00 0.00 0.00 0.00 0.20 0.02 0.00 0.00 0.00 3.23 0.00
Appendix 2 71

Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued[Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity]

Observation name Observation group Recharge parameters HK_Till HK_wetland HK_ShearZn HK_ClayEXP Moraines Sandy_1 Till Wetlands Bedrock Alluv_Urb Sandy_2 RCH_Xtra

ME_YW_869 Till dug -1.60 -0.05 0.00 -0.16 0.00 10.53 3.46 0.12 0.47 0.12 0.52 0.00ME_YW_877 Till dug -0.10 -0.14 0.00 -0.00 0.00 0.01 1.99 0.02 0.44 0.00 0.12 0.00ME_YW_880 Till dug -0.70 -0.01 0.00 -0.00 0.02 0.02 1.40 0.05 1.56 0.00 0.08 0.00ME_YW_881 Till dug -0.54 -0.11 0.00 -0.00 0.01 0.77 3.31 0.38 0.39 0.00 0.10 0.00ME_YW_899 Till dug -0.30 -0.00 0.00 0.00 0.03 0.01 0.21 0.00 0.01 0.00 0.00 0.00ME_YW_904 Till dug -9.86 -0.00 0.00 -0.14 0.01 10.78 8.20 0.05 1.03 0.14 7.37 0.00ME_YW_964 Till dug -3.38 -0.01 0.00 -0.01 0.02 0.22 8.84 0.02 0.11 1.02 0.59 0.00Genest_33_81 Genest 0.01 -0.01 -0.03 0.54 0.00 1.49 0.02 0.06 0.00 0.01 0.25 0.00Genest_34D Genest 0.00 -0.01 -0.05 0.31 0.00 1.50 0.01 0.07 0.00 0.01 0.33 0.00Genest_34B Genest 0.00 -0.01 -0.05 0.28 0.00 1.50 0.01 0.08 0.00 0.01 0.37 0.00Genest_34A Genest 0.00 -0.01 -0.05 0.26 0.00 1.49 0.01 0.08 0.00 0.01 0.37 0.00Genest_34_81 Genest 0.00 -0.01 -0.05 0.27 0.00 1.49 0.01 0.08 0.00 0.01 0.37 0.00Genest_34C Genest 0.00 -0.01 -0.05 0.24 0.00 1.48 0.01 0.08 0.00 0.01 0.36 0.00Genest_34E Genest 0.00 -0.01 -0.05 0.22 0.00 1.45 0.01 0.08 0.00 0.01 0.36 0.00Genest_59_81 Genest 0.00 -0.02 -0.06 0.07 0.00 1.46 0.01 0.10 0.00 0.01 0.44 0.00KKW_MWHR4 Herrisecket Rd. -0.44 -0.00 0.00 -4.35 0.00 20.15 0.36 0.05 0.03 0.04 4.82 0.00KKW_MWHR11 Herrisecket Rd. -0.13 -0.00 0.00 6.68 0.00 8.37 0.19 0.10 0.01 0.06 3.84 0.00KKW_MWHR1 Herrisecket Rd. -0.39 -0.00 0.00 -0.39 0.00 18.68 0.35 0.06 0.02 0.05 4.79 0.00KKW_MWHR3 Herrisecket Rd. -0.40 -0.00 0.00 -0.32 0.00 18.71 0.35 0.06 0.02 0.05 4.82 0.00KKW_MWHR6 Herrisecket Rd. -0.47 -0.00 0.00 -4.87 0.00 23.58 0.38 0.05 0.03 0.05 5.10 0.00KKW_MWHR7 Herrisecket Rd. -0.54 0.00 0.00 -4.20 0.00 15.07 1.46 0.06 0.06 0.17 18.43 0.00KKW_MWHR8 Herrisecket Rd. -0.84 0.00 0.00 -8.29 0.00 31.74 0.68 0.06 0.05 0.06 8.26 0.00KKW_MWHR12 Herrisecket Rd. -0.12 -0.00 0.00 6.59 0.00 7.90 0.18 0.10 0.01 0.06 3.79 0.00KKW_MWMR13 Merriland 0.00 -0.01 0.00 0.36 0.00 3.16 0.03 0.01 0.00 0.02 0.41 0.00KKW_MWMR18 Merriland 0.01 -0.00 0.00 0.52 0.00 3.72 0.04 0.01 0.00 0.02 0.46 0.00KKW_MWMR10 Merriland -0.04 -0.00 0.00 2.00 0.00 10.35 0.08 0.01 0.00 0.02 0.58 0.00KKW_MWMR9 Merriland 0.00 -0.00 0.00 0.60 0.00 4.56 0.04 0.02 0.00 0.02 0.54 0.00KKW_DPMR3 Merriland 0.03 -0.00 0.00 0.13 0.00 10.56 0.03 0.00 0.00 0.07 0.29 0.00KKW_MWMR6 Merriland 0.01 -0.00 0.00 0.52 0.00 3.71 0.05 0.01 0.00 0.02 0.46 0.00KKW_MWMR1 Merriland 0.01 -0.00 0.00 0.51 0.00 3.66 0.05 0.01 0.00 0.02 0.46 0.00KKW_DPMR1 Merriland 0.00 -0.00 0.00 0.02 0.00 5.25 0.01 0.00 0.00 0.36 0.09 0.00KKW_MWMR16 Merriland -0.00 -0.01 0.00 -6.09 0.00 13.65 0.00 0.07 0.00 0.05 0.04 0.00KKW_MWMR15 Merriland -0.00 -0.02 0.00 -2.29 0.00 11.44 0.00 0.08 0.00 0.03 0.02 0.00KKW_MWMR11 Merriland 0.03 -0.00 0.00 0.42 0.00 3.03 0.08 0.01 0.00 0.02 0.49 0.00KKW_MWMR8 Merriland 0.00 -0.00 0.00 0.67 0.00 4.46 0.05 0.01 0.00 0.03 0.50 0.00KKW_MWMR14 Merriland 0.00 -0.00 0.00 0.27 0.00 2.02 0.02 0.01 0.00 0.02 0.25 0.00KKW_MWMR5 Merriland 0.00 -0.00 0.00 0.50 0.00 3.74 0.04 0.01 0.00 0.02 0.46 0.00
72 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued [Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity] Observation name Observation group Recharge parameters HK_Till HK_wetland HK_ShearZn HK_ClayEXP Moraines Sandy_1 Till Wetlands Bedrock Alluv_Urb Sandy_2 RCH_Xtra DEPCyro_X2 Sanford-Cyro -0.01 -0.06 -0.00 -1.83 0.00 3.40 0.06 0.06 0.01 0.13 1.76 0.00 DEP_MW03_02 Sanford-Cyro -0.00 -0.00 0.00 -0.30 0.00 0.57 0.02 0.01 0.01 0.01 0.24 0.00 DEP_MW101A Sanford-Cyro -0.01 -0.02 0.00 -1.24 0.00 2.73 0.22 0.02 0.09 0.12 2.30 0.00 DEP_MW104A Sanford-Cyro -0.00 -0.01 0.00 -1.00 0.00 2.15 0.07 0.02 0.03 0.07 1.03 0.00 DEP_MW104BR Sanford-Cyro -0.00 -0.01 -0.00 -1.07 0.00 1.37 0.07 0.02 0.02 0.06 0.92 0.00 DEP_MW201A Sanford-Cyro -0.01 -0.02 0.00 -1.55 0.00 2.62 0.12 0.03 0.05 0.14 2.36 0.00 DEP_MW204A Sanford-Cyro -0.00 -0.01 -0.00 -0.56 0.00 1.04 0.02 0.01 0.01 0.03 0.39 0.00 DEP_MW204B Sanford-Cyro -0.00 -0.01 -0.00 -0.58 0.00 0.81 0.02 0.01 0.01 0.03 0.44 0.00 DEP_MW205B Sanford-Cyro -0.00 -0.02 -0.00 -1.00 0.00 1.36 0.04 0.02 0.02 0.06 0.80 0.00 DEP_MW209A Sanford-Cyro -0.00 -0.02 -0.00 -1.06 0.00 1.94 0.03 0.02 0.01 0.05 0.68 0.00 DEP_MW702B Sanford-Cyro -0.00 -0.00 0.00 -0.19 0.00 0.36 0.02 0.01 0.01 0.01 0.16 0.00 SWD_IDC_M1 Sanford -0.02 -0.10 -0.00 -0.32 0.00 3.17 0.07 0.08 0.01 0.07 1.64 0.00 SWD_IDC_M4 Sanford -0.02 -0.09 -0.00 -1.37 0.00 3.48 0.07 0.08 0.01 0.09 1.95 0.00 SWD_Eagle_6 Sanford -0.01 -0.09 -0.00 4.03 0.00 2.54 0.08 0.07 0.00 0.05 1.19 0.00 SWD_Eagle_6a Sanford -0.01 -0.09 -0.00 6.61 0.00 2.62 0.08 0.07 0.00 0.06 1.24 0.00 SWD_Eagle_7 Sanford -0.01 -0.10 -0.00 0.18 0.00 2.38 0.07 0.07 0.00 0.05 1.03 0.00 SWD_Eagle_1 Sanford -0.01 -0.10 0.00 0.01 0.00 2.05 0.07 0.07 0.00 0.04 0.87 0.00 SWD_Eagle_2 Sanford -0.01 -0.09 0.00 6.84 0.00 2.62 0.08 0.07 0.00 0.06 1.24 0.00 SWD_ND_1 Sanford -0.00 -0.06 0.00 -3.48 0.00 2.35 0.00 0.10 0.00 0.00 2.14 0.00 SWD_ND_4 Sanford -0.00 -0.06 0.00 -3.45 0.00 2.37 0.00 0.10 0.00 0.00 2.13 0.00 SWD_ND_GP Sanford -0.00 -0.06 0.00 -3.48 0.00 2.35 0.00 0.10 0.00 0.00 2.15 0.00

Sanford_wet1 SW points -0.05 -1.51 0.00 -2.82 0.00 1.29 0.02 0.35 0.02 0.00 5.54 0.00Saywards_Wet SW points 0.02 -0.89 0.05 0.06 0.00 4.02 0.19 0.29 0.03 0.00 0.24 0.00Airport_S SW points -0.01 -0.00 -0.00 -0.10 0.00 0.15 0.02 0.21 0.01 0.11 0.71 0.00Airport_SW SW points -0.01 -0.00 -0.00 -1.29 0.00 0.05 0.03 0.02 0.04 0.12 2.53 0.00Merri_head SW points -0.01 -1.79 0.27 0.09 0.00 0.31 0.11 0.95 0.04 0.00 1.22 0.00Till_up_wet SW points -1.71 -2.28 -0.00 -0.03 1.88 2.70 4.34 1.07 0.61 0.00 1.64 0.04Merri_S_wet SW points -0.02 0.10 0.00 0.00 0.00 0.00 0.06 0.10 0.04 0.00 0.49 0.00Ocean_wet SW points 0.04 -0.83 0.00 -0.00 0.00 0.31 0.00 0.40 0.03 0.00 0.57 0.00RR_wet_N SW points -0.00 -0.00 0.00 0.05 0.00 0.46 0.02 0.39 0.00 0.01 3.33 0.00RR_wet_S SW points -0.00 -0.20 0.00 -0.02 0.00 0.90 0.02 0.66 0.10 0.01 9.41 0.00Perkins_Msh SW points -0.00 0.15 0.00 0.01 0.00 0.27 0.00 0.06 0.00 0.00 0.24 0.00Estes_Lake_1 SW points 0.00 0.00 0.00 -0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Estes_Lake_2 SW points 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Estes_Lake_3 SW points 0.00 -0.00 0.00 -0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00OldFallsPond SW points 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Appendix 2 73

Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued[Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity]

Observation name Observation group Recharge parameters HK_Till HK_wetland HK_ShearZn HK_ClayEXP Moraines Sandy_1 Till Wetlands Bedrock Alluv_Urb Sandy_2 RCH_Xtra

Merri2_Str_1 Baseflows -0.02 -0.35 -0.04 0.10 -0.23 -2.68 -1.64 -0.54 -0.36 -0.12 -2.87 -0.00Merri1_Str_1 Baseflows 0.01 0.00 0.00 0.10 0.00 -1.61 -0.12 -0.00 -0.00 -0.00 -0.28 0.00Perkins_st_1 Baseflows 0.01 -0.13 0.00 0.31 0.00 -5.31 -0.12 -0.27 -0.03 -0.01 -9.23 -0.01Cold_seeps_1 Baseflows 0.02 0.08 0.00 0.05 0.00 -13.77 -0.00 -0.05 -0.02 -0.04 -1.38 -0.23BB7_Str_1 Baseflows 0.01 0.04 0.02 0.59 0.00 -3.44 -0.05 -0.34 -0.01 -0.31 -3.27 -0.00BB6_Str_1 Baseflows -0.01 0.05 0.16 -0.55 0.00 -5.24 -0.06 -0.68 -0.01 -0.08 -1.79 -0.00BB5_Seeps_1 Baseflows 0.01 0.01 0.00 0.06 -0.00 -3.47 -0.07 -0.04 -0.01 -0.02 -0.50 -0.03BB4_Seeps_1 Baseflows 0.01 0.01 0.00 0.02 -0.00 -1.43 -0.02 -0.00 -0.00 -0.03 -0.93 -0.02BB4_Str_1 Baseflows 0.04 0.08 0.00 0.05 -0.02 -4.47 -0.21 -0.07 -0.03 -0.02 -2.02 -0.16BB3_Seeps_1 Baseflows 0.01 0.03 0.00 0.07 -0.00 -9.89 -0.05 -0.03 -0.01 -0.09 -0.68 -0.18BB2_Seeps_1 Baseflows -0.03 0.00 0.00 0.08 -0.00 -4.62 -0.17 -0.00 -0.02 -0.02 -0.52 -0.01BB2_Str_1 Baseflows 0.11 0.12 0.00 0.03 -0.04 -3.41 -0.63 -0.04 -0.08 -0.09 -3.24 -0.01BB1_Seeps_1 Baseflows -0.02 0.00 0.00 0.14 -0.00 -3.70 -1.36 -0.05 -0.03 -0.07 -3.57 0.00BB8_Str_1 Baseflows -0.07 -0.01 0.00 0.43 -0.00 -3.01 -0.15 -0.00 -0.05 -0.00 -0.39 0.00Day_Seeps_1 Baseflows -0.26 0.00 0.00 0.13 0.00 -2.26 -0.43 -0.03 -0.08 -0.02 -0.09 -0.00Day_Str_1 Baseflows 0.01 0.00 0.00 0.14 0.00 -7.18 -0.08 -0.03 -0.02 -0.07 -1.70 -0.18Merri2_Riv_1 Baseflows -0.17 0.00 0.00 -0.01 -0.00 -0.09 -2.23 -0.00 -0.30 -0.01 -0.11 0.00Merri1_Riv_1 Baseflows -0.01 0.00 0.00 -0.02 0.00 -1.84 -0.13 -0.01 -0.00 -0.09 -0.61 0.00BB5_Riv_1 Baseflows 0.01 0.02 0.01 -0.13 -0.00 -3.07 -0.04 -0.02 -0.01 -0.05 -0.16 -0.01BB3_Riv_1 Baseflows 0.01 0.01 0.00 -0.43 -0.00 -5.78 -0.03 -0.09 -0.00 -0.22 -0.37 -0.06BB2_Riv_1 Baseflows -0.00 0.00 0.00 -0.10 0.00 -0.96 -0.03 -0.00 -0.00 -0.04 -0.16 -0.00BB1_Riv_1 Baseflows 0.03 0.00 0.00 -0.48 0.00 -2.49 -0.37 -0.11 -0.01 -0.26 -2.93 0.00
74 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued [Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity] Observation name Observation group Stream and river conductance parameters KDR_ Seeps KDR_ Stream KRIV_BB KRIV_ Merri KRIV_ Mous Nestle_MW01 BB-North -7.72 -0.09 -0.69 0.00 -0.00 Nestle_MW06 BB-North -8.08 -0.14 -0.54 0.00 -0.00 Nestle_MW13 BB-North -7.76 -0.11 -0.71 0.00 -0.00 Nestle_MW14 BB-North -10.14 -0.07 -0.26 0.00 -0.00 Nestle_MW16 BB-North -9.99 -0.05 -0.13 0.00 0.00 Nestle_MW24 BB-North -7.28 -0.08 -0.95 0.00 -0.00 Nestle_MW33 BB-North -10.25 -0.06 -0.25 0.00 0.00 Nestle_MW41 BB-North -10.69 -0.05 -0.24 0.00 0.00 Nestle_MW44 BB-North -10.26 -0.06 -0.16 0.00 -0.00 Nestle_MW45 BB-North -10.27 -0.05 -0.15 0.00 0.00 Nestle_MW46 BB-North -9.56 -0.08 -0.31 0.00 -0.00 Nestle_MW47 BB-North -9.61 -0.09 -0.25 0.00 0.00 KKW_MW02 BB-North -9.49 -0.14 -0.79 0.00 -0.00 KKW_MW07A BB-North -9.52 -0.12 -0.80 0.00 -0.00 KKW_MW15 BB-North -12.15 -0.05 -0.14 0.00 0.00 KKW_MW23 BB-North -9.57 -0.09 -0.74 0.00 -0.00 KKW_MW26 BB-North -9.22 -0.13 -0.89 0.00 -0.00 KKW_MW30 BB-North -10.97 -0.08 -0.49 0.00 0.00 KKW_MW35 BB-North -13.60 -0.05 -0.19 0.00 -0.00 KKW_MW48 BB-North -12.02 -0.08 -0.21 0.00 -0.00

TNC_MW202 BB-South -7.63 -1.68 -0.03 0.00 0.00TNC_MW204 BB-South -5.34 -1.90 -0.02 0.00 0.00TNC_MW101 BB-South -12.85 -1.20 -0.04 0.00 0.00TNC_MW105 BB-South -10.44 -1.43 -0.03 0.00 0.00TNC_MW106 BB-South -6.28 -1.85 -0.02 0.00 0.00TNC_MW103 BB-South -10.48 -1.25 -0.04 0.00 0.00TNC_MW107 BB-South -10.75 -1.24 -0.04 0.00 0.00TNC_MW109 BB-South -12.29 -1.10 -0.04 0.00 0.00TNC_MW110 BB-South -9.44 -1.53 -0.04 0.00 0.00TNC_MW304 BB-South -10.74 -1.42 -0.04 0.00 0.00TNC_MW308 BB-South -8.58 -1.49 -0.03 0.00 0.00TNC_MW310 BB-South -8.17 -1.51 -0.03 0.00 0.00TNC_MW401 BB-South -10.84 -1.28 -0.04 0.00 0.00TNC_MW410 BB-South -11.14 -1.24 -0.04 0.00 0.00TNC_MW422 BB-South -6.31 -1.15 -0.07 0.00 0.00
Appendix 2 75

Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued[Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity]

Observation name Observation group Stream and river conductance parameters KDR_ Seeps KDR_ Stream KRIV_BB KRIV_ Merri KRIV_ Mous

TNC_MW430 BB-South -2.59 -1.60 -0.02 0.00 0.00TNC_MW403 BB-South -12.70 -1.04 -0.05 0.00 0.00TNC_MW404 BB-South -11.57 -1.09 -0.05 0.00 0.00TNC_MW415 BB-South -12.18 -1.11 -0.05 0.00 0.00TNC_MW425 BB-South -9.39 -1.55 -0.03 0.00 0.00TNC_MW433 BB-South -9.09 -1.54 -0.03 0.00 0.00TNC_MW440 BB-South -11.14 -1.18 -0.04 0.00 0.00TNC_MW315 BB-South -9.96 -1.32 -0.04 0.00 0.00ME_YW_870 Bedrock -0.81 -0.21 -0.00 0.00 -0.00ME_YW_878 Bedrock -0.00 -0.46 0.00 0.00 0.00ME_YW_882 Bedrock -0.30 -0.47 -0.06 0.00 0.00ME_YW_883 Bedrock 0.00 -0.54 0.00 0.00 0.00ME_YW_888 Bedrock -0.00 -0.37 -0.00 0.00 0.00ME_YW_891 Bedrock -0.05 -0.03 -0.02 -0.03 -0.01ME_YW_894 Bedrock -0.00 -0.01 -0.01 -0.08 -0.00ME_YW_896 Bedrock -0.00 -0.06 0.00 -0.00 -0.01ME_YW_897 Bedrock -0.10 -0.18 -0.00 -0.01 -0.00ME_YW_901 Bedrock -0.18 -0.78 -0.00 0.00 0.00ME_YW_871 Coastal sands dug -0.15 -0.36 -0.04 -0.68 -0.00ME_YW_872 Coastal sands dug -0.14 -0.39 -0.04 -0.57 -0.00ME_YW_873 Coastal sands dug -0.08 -0.56 -0.01 -0.11 -0.00ME_YW_890 Coastal sands dug -2.34 -0.20 -0.02 -0.03 -0.02ME_YW_892 Coastal sands dug -1.74 -0.61 -0.03 -0.06 -0.02ME_YW_893 Coastal sands dug -0.00 -0.03 -0.02 -0.39 0.00ME_YW_906 Coastal sands dug -0.04 -0.48 -0.01 -0.05 -0.00ME_YW_874 Delta sands dug -1.04 -0.86 -0.00 -0.00 -0.04ME_YW_875 Delta sands dug -1.89 -1.77 -0.00 0.00 -0.00ME_YW_876 Delta sands dug -3.76 -1.01 -0.03 0.00 -0.00ME_YW_884 Delta sands dug -2.45 -1.22 -0.56 0.00 0.00ME_YW_885 Delta sands dug -0.20 -1.67 -0.32 0.00 0.00ME_YW_886 Delta sands dug -0.11 -2.29 -0.01 0.00 0.00ME_YW_900 Delta sands dug -0.31 -3.59 -0.00 0.00 0.00ME_YW_902 Delta sands dug -0.04 -0.69 -0.00 0.00 -0.00
76 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued [Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity] Observation name Observation group Stream and river conductance parameters KDR_ Seeps KDR_ Stream KRIV_BB KRIV_ Merri KRIV_ Mous ME_YW_903 Delta sands dug -2.30 -1.14 -0.01 0.00 0.00 ME_YW_905 Delta sands dug -0.00 -0.18 0.00 0.00 -0.00 ME_YW_907 Delta sands dug -3.57 -1.70 -0.01 0.00 0.00 ME_YW_908 Delta sands dug -4.29 -1.99 -0.00 0.00 0.00 ME_YW_909 Delta sands dug -0.93 -0.52 -0.01 0.00 -0.00 ME_YW_963 Delta sands dug -0.07 -0.53 -0.04 -0.07 -0.00 ME_YW_965 Delta sands dug -0.35 -0.62 -0.70 0.00 0.00 ME_YW_966 Delta sands dug -0.03 -0.04 -0.06 0.00 0.00 ME_YW_869 Till dug -0.18 -0.33 -0.00 -0.00 -0.02 ME_YW_877 Till dug 0.00 -0.16 0.00 0.00 0.00 ME_YW_880 Till dug -0.00 -0.18 0.00 0.00 0.00 ME_YW_881 Till dug -0.04 -0.47 -0.00 0.00 0.00 ME_YW_899 Till dug 0.00 -0.09 0.00 0.00 0.00 ME_YW_904 Till dug -1.24 -0.13 -0.02 -0.01 0.00 ME_YW_964 Till dug -0.03 -0.18 -0.00 -0.00 -0.00 Genest_33_81 Genest -0.03 -0.58 -0.03 0.00 -0.00 Genest_34D Genest -0.02 -0.61 -0.02 0.00 0.00 Genest_34B Genest -0.02 -0.61 -0.02 0.00 -0.00

Genest_34A Genest -0.02 -0.61 -0.02 0.00 -0.00Genest_34_81 Genest -0.02 -0.61 -0.02 0.00 -0.00Genest_34C Genest -0.02 -0.62 -0.02 0.00 -0.00Genest_34E Genest -0.02 -0.62 -0.02 0.00 -0.00Genest_59_81 Genest -0.02 -0.59 -0.02 0.00 -0.00KKW_MWHR4 Herrisecket Rd. -0.34 -0.38 -0.08 -0.57 -0.00KKW_MWHR11 Herrisecket Rd. -0.32 -0.14 -0.16 -1.04 -0.00KKW_MWHR1 Herrisecket Rd. -0.35 -0.35 -0.09 -0.61 -0.00KKW_MWHR3 Herrisecket Rd. -0.35 -0.35 -0.09 -0.61 -0.00KKW_MWHR6 Herrisecket Rd. -0.36 -0.37 -0.08 -0.59 -0.00KKW_MWHR7 Herrisecket Rd. -1.86 -0.17 -0.04 -1.41 -0.00KKW_MWHR8 Herrisecket Rd. -0.55 -0.39 -0.07 -0.68 -0.00KKW_MWHR12 Herrisecket Rd. -0.32 -0.14 -0.16 -1.05 -0.00
Appendix 2 77

Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued[Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity]

Observation name Observation group Stream and river conductance parameters KDR_ Seeps KDR_ Stream KRIV_BB KRIV_ Merri KRIV_ Mous

KKW_MWMR13 Merriland -0.06 -0.05 -0.09 0.31 -0.00KKW_MWMR18 Merriland -0.05 -0.06 -0.08 0.55 -0.00KKW_MWMR10 Merriland -0.05 -0.41 -0.06 0.15 -0.00KKW_MWMR9 Merriland -0.06 -0.08 -0.11 0.38 -0.00KKW_DPMR3 Merriland -0.03 -0.03 -0.03 -0.11 -0.00KKW_MWMR6 Merriland -0.05 -0.06 -0.08 0.53 -0.00KKW_MWMR1 Merriland -0.05 -0.06 -0.08 0.54 -0.00KKW_DPMR1 Merriland -0.02 -0.01 -0.01 -0.60 -0.00KKW_MWMR16 Merriland -0.00 -0.02 -0.01 -0.22 0.00KKW_MWMR15 Merriland -0.00 -0.01 -0.02 -0.66 -0.00KKW_MWMR11 Merriland -0.04 -0.05 -0.06 0.61 -0.00KKW_MWMR8 Merriland -0.05 -0.07 -0.09 0.79 -0.00KKW_MWMR14 Merriland -0.03 -0.03 -0.05 0.25 -0.00KKW_MWMR5 Merriland -0.05 -0.06 -0.09 0.45 -0.00DEPCyro_X2 Sanford-Cyro -0.07 -0.23 -0.00 0.00 -0.05DEP_MW03_02 Sanford-Cyro -0.00 -0.02 -0.00 0.00 -0.08DEP_MW101A Sanford-Cyro -0.02 -0.09 -0.00 0.00 -0.08DEP_MW104A Sanford-Cyro -0.02 -0.06 -0.00 0.00 -0.09DEP_MW104BR Sanford-Cyro -0.02 -0.07 -0.00 0.00 -0.10DEP_MW201A Sanford-Cyro -0.03 -0.12 -0.00 0.00 -0.08DEP_MW204A Sanford-Cyro -0.01 -0.03 -0.00 0.00 -0.09DEP_MW204B Sanford-Cyro -0.01 -0.04 -0.00 0.00 -0.11DEP_MW205B Sanford-Cyro -0.02 -0.07 -0.00 0.00 -0.10DEP_MW209A Sanford-Cyro -0.02 -0.07 -0.00 0.00 -0.09DEP_MW702B Sanford-Cyro -0.00 -0.01 0.00 0.00 -0.08SWD_IDC_M1 Sanford -0.11 -0.31 -0.01 0.00 -0.03SWD_IDC_M4 Sanford -0.13 -0.32 -0.01 0.00 -0.03SWD_Eagle_6 Sanford -0.07 -0.28 -0.00 0.00 -0.03SWD_Eagle_6a Sanford -0.08 -0.29 -0.00 0.00 -0.03SWD_Eagle_7 Sanford -0.06 -0.28 -0.00 0.00 -0.03SWD_Eagle_1 Sanford -0.05 -0.27 -0.00 0.00 -0.02SWD_Eagle_2 Sanford -0.08 -0.29 -0.00 0.00 -0.03SWD_ND_1 Sanford 0.00 -0.13 0.00 0.00 -0.02SWD_ND_4 Sanford -0.00 -0.13 0.00 0.00 -0.02SWD_ND_GP Sanford 0.00 -0.13 0.00 0.00 -0.02
78 Simulation of Groundwater Flow in the Branch Brook Watershed, Maine Table 2–1. Dimensionless scaled sensitivities for parameters, by observation groups.—Continued [Parameters defined in text and tables 11, 12, and 15; K, hydraulic conductivity] Observation name Observation group Stream and river conductance parameters KDR_ Seeps KDR_ Stream KRIV_BB KRIV_ Merri KRIV_ Mous Sanford_wet1 SW points -0.00 -0.07 0.00 0.00 -0.08 Saywards_Wet SW points -0.09 -2.71 -0.03 0.00 0.00 Airport_S SW points -0.01 -0.37 -0.00 0.00 -0.00 Airport_SW SW points -0.00 -0.26 -0.00 0.00 -0.00 Merri_head SW points -0.00 -1.31 -0.00 0.00 0.00 Till_up_wet SW points -0.60 -2.22 -0.00 0.00 0.00 Merri_S_wet SW points 0.00 -0.71 0.00 0.00 0.00 Ocean_wet SW points -0.00 -0.52 -0.00 -0.00 0.00 RR_wet_N SW points -0.03 -0.34 -0.03 -0.05 -0.00 RR_wet_S SW points -0.03 -0.74 -0.06 -0.05 -0.00 Perkins_Msh SW points -0.04 -0.80 -0.00 0.00 -0.00 Estes_Lake_1 SW points 0.00 -0.01 0.00 0.00 0.00 Estes_Lake_2 SW points 0.00 0.00 0.00 0.00 0.00 Estes_Lake_3 SW points 0.00 -0.00 0.00 0.00 0.00 OldFallsPond SW points 0.00 0.00 0.00 0.00 0.00 Merri2_Str_1 Baseflows 0.07 -0.19 0.01 0.00 0.00 Merri1_Str_1 Baseflows 0.00 -0.12 0.00 0.09 0.00 Perkins_st_1 Baseflows 0.58 -0.44 0.01 0.00 0.01 Cold_seeps_1 Baseflows -0.17 0.17 0.01 0.00 0.00

BB7_Str_1 Baseflows 0.18 -0.19 0.02 0.00 0.01BB6_Str_1 Baseflows 0.08 0.34 0.13 0.00 0.00BB5_Seeps_1 Baseflows -0.73 0.07 0.21 0.00 0.00BB4_Seeps_1 Baseflows -0.43 0.26 0.00 0.00 0.00BB4_Str_1 Baseflows 1.57 -0.16 0.01 0.00 0.00BB3_Seeps_1 Baseflows -2.27 0.16 0.09 0.00 0.00BB2_Seeps_1 Baseflows -1.19 0.09 0.06 0.00 0.00BB2_Str_1 Baseflows 0.49 -0.15 0.01 0.00 0.00BB1_Seeps_1 Baseflows -1.05 0.04 0.04 0.33 0.00BB8_Str_1 Baseflows 0.02 -0.03 0.01 0.03 0.00Day_Seeps_1 Baseflows -0.15 0.17 0.00 0.00 0.00Day_Str_1 Baseflows 0.85 -0.22 0.01 0.00 0.00Merri2_Riv_1 Baseflows 0.00 0.05 0.00 0.01 -0.02Merri1_Riv_1 Baseflows 0.01 0.06 0.01 0.08 0.00BB5_Riv_1 Baseflows 0.77 0.10 -0.41 0.00 0.00BB3_Riv_1 Baseflows 1.97 0.07 -0.35 0.00 0.00BB2_Riv_1 Baseflows 0.21 0.02 -0.03 -0.01 0.00BB1_Riv_1 Baseflows 0.39 0.06 0.14 -0.72 0.00
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Nielsen and Locke—Simulation of Groundwater Flow in the Branch Brook Watershed, Maine—Scientific Investigations Report 2014–5235

ISSN 2328-0328 (online)

http://dx.doi.org/10.3133/sir20145235