Amicus Curiae Brief — County of Maui, Hawaii, Petitioner v. Hawaii Wildlife Fund, et al.

Supreme Court briefJul 19, 2019

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No. 18-260

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In The

Supreme Court of the United States

-----------------------------------------------------------------COUNTY OF MAUI,

Petitioner,

HAWAI‘I WILDLIFE FUND; SIERRA CLUB –

MAUI GROUP; SURFRIDER FOUNDATION;

WEST MAUI PRESERVATION ASSOCIATION,

Respondents.

-----------------------------------------------------------------On Writ Of Certiorari To The

United States Court Of Appeals

For The Ninth Circuit

-----------------------------------------------------------------BRIEF FOR AQUATIC SCIENTISTS AND

SCIENTIFIC SOCIETIES AS AMICI CURIAE

IN SUPPORT OF RESPONDENTS

-----------------------------------------------------------------DR. STEPH TAI

UNIVERSITY OF WISCONSIN

LAW SCHOOL

975 Bascom Mall

Madison, WI 57306

CHRISTOPHER W. GREER

WHITE & CASE LLP

1221 Avenue of the Americas

New York, NY 10020

ROYAL C. GARDNER

Attorney of Record

ERIN OKUNO

KATHLEEN E. GARDNER

STETSON UNIVERSITY

COLLEGE OF LAW

INSTITUTE FOR BIODIVERSITY

LAW AND POLICY

1401 61st Street South

Gulfport, FL 33707

gardner@law.stetson.edu

727-562-7864

Counsel for Amici Curiae

Aquatic Scientists and Scientiﬁc Societies

July 19, 2019

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COCKLE LEGAL BRIEFS (800) 225-6964

WWW.COCKLELEGALBRIEFS.COM

QUESTION PRESENTED

Whether the Clean Water Act requires a permit for the

discharge of pollutants when the pollutants travel

through groundwater from a point source to navigable

waters.

TABLE OF CONTENTS

Page

QUESTION PRESENTED...................................

TABLE OF CONTENTS ......................................

TABLE OF AUTHORITIES .................................

INTERESTS OF AMICI CURIAE .......................

SUMMARY OF ARGUMENT ..............................

ARGUMENT ........................................................

INTRODUCTION TO HYDROLOGIC CONCEPTS AND GROUNDWATER ..................

A. Groundwater Storage ..........................

B. Groundwater Flows ............................. 11

II. ROBUST SCIENTIFIC METHODS CAN

MEASURE THE EXTENT TO WHICH

GROUNDWATER CONNECTS POINT

SOURCES TO SURFACE WATERS ........... 13

A. Physical Measurements ...................... 14

B. Chemical Tracer Methods ................... 18

C. Groundwater Models ........................... 22

D. Applying Robust Scientific Methods to

Track Pollutants in Groundwater ....... 26

III.

THE CLEAN WATER ACT REQUIRES THE

CONSIDERATION OF THE SCIENCE REGARDING GROUNDWATER AND SURFACE WATER CONNECTIONS ................ 28

A. The Clean Water Act Requires Consideration of Science to Meet Its Objective ....................................................... 29

iii

TABLE OF CONTENTS—Continued

Page

B. Congress’s Inclusion of the Terms

“Well” and “Discrete Fissure” in the

Definition of Point Source Demonstrates Its Intent that the Clean Water

Act Regulates Discharges of Pollutants to Groundwater .......................... 31

C. The Science Behind the Hydrological

Connectivity of Groundwater and Surface Waters Supports the Ninth Circuit’s Fairly Traceable Test, Whereas

the Petitioner’s Means-of-Delivery Test

Is Not Workable and Is Not Supported

by Science ............................................ 34

CONCLUSION..................................................... 36

APPENDIX

Biographies and Descriptions of Amici Curiae .... App. 1

TABLE OF AUTHORITIES

Page

CASES

Assateague Coastkeeper v. Alan & Kristin Hudson Farm, 727 F. Supp. 2d 433 (D. Md. 2010) ........29

Babbitt v. Sweet Home Chapter of Communities

for a Great Or., 515 U.S. 687 (1995) .................. 31, 35

Baltimore Gas & Elec. Co. v. Nat. Res. Def. Council, Inc., 462 U.S. 87 (1983) ......................................30

Cmty. Ass’n for the Restoration of the Env’t v.

Nelson Faria Dairy, Inc., No. CV-04-3060-LRS,

2011 WL 6934707 (E.D. Wash. Dec. 30, 2011) ........30

Duncan v. Walker, 533 U.S. 167 (2001) ......................31

Greater Yellowstone Coal. v. Larson, 641 F. Supp. 2d

1120 (D. Idaho 2009) ......................................... 30, 35

United States v. Acquest Transit LLC, No. 09-CV00055S(F), 2018 WL 3861612 (W.D.N.Y. Aug.

14, 2018) ..................................................................30

United States v. Donovan, 661 F.3d 174 (3d Cir.

2011) ........................................................................30

United States v. Jicarilla Apache Nation, 564

U.S. 162 (2011) ........................................................31

United States v. Riverside Bayview Homes, Inc.,

474 U.S. 121 (1985) .................................................29

STATUTES

33 U.S.C. § 1251(a) ........................................................5

33 U.S.C. § 1311(a) ......................................................29

TABLE OF AUTHORITIES—Continued

Page

33 U.S.C. § 1342(a) ......................................................29

33 U.S.C. § 1362(14) ....................................................32

42 U.S.C. § 300f et seq. ...............................................33

LEGISLATIVE MATERIAL

1 Cong. Research Serv., A Legislative History of

the Water Pollution Control Act Amendments

of 1972 (1973) ..........................................................33

H.R. Rep. No. 92-911 (1972) .......................................29

H.R. Rep. No. 93-1185 (1974) .....................................34

ADMINISTRATIVE MATERIAL

U.S. Envtl. Prot. Agency, Interpretive Statement

on Application of the Clean Water Act National Pollutant Discharge Elimination System Program to Releases of Pollutants from a

Point Source to Groundwater, 84 Fed. Reg.

16,810 (Apr. 23, 2019) .............................................31

U.S. Envtl. Prot. Agency, Op. of Acting Deputy

Gen. Counsel No. 590 (Dec. 13, 1973) .....................34

SCIENTIFIC AUTHORITIES

Mary P. Anderson, Heat as a Ground Water

Tracer, 43 Ground Water 951 (2005) ......................20

Mary P. Anderson et al., Applied Groundwater

Modeling: Simulation of Flow and Advective

Transport (2d ed. 2015) ..................................... 14, 26

TABLE OF AUTHORITIES—Continued

Page

Vedat Batu, Aquifer Hydraulics: A Comprehensive Guide to Hydrogeologic Data Analysis

(1998) .........................................................................8

Sebastian Bauer et al., A Multi-Tracer Study in

a Shallow Aquifer Using Age Dating Tracers

H, 85Kr, CFC-113 and SF6—Indication for Retarded Transport of CFC-113, 248 J. Hydrology 14 (2001) ...........................................................20

E.R. Bayless et al., Accuracy of Flowmeters

Measuring Horizontal Groundwater Flow in

an Unconsolidated Aquifer Simulator, 31

Ground Water Monitoring & Remediation 48

(2011) .......................................................................15

Mark M. Brinson, A Hydrogeomorphic Classiﬁcation for Wetlands (Wetlands Research Program Tech. Report WRP-DE-4, 1993) .......................9

Ross Brodie et al., An Overview of Tools for Assessing Groundwater-Surface Water Connectivity (2007) ....................................................... 18, 20

Douglas A. Burns & Long Nguyen, Nitrate

Movement and Removal Along a Shallow

Groundwater Flow Path in a Riparian Wetland Within a Sheep‐Grazed Pastoral Catchment: Results of a Tracer Study, 36 N.Z. J.

Marine & Freshwater Res. 371 (2002) ...................18

Jaye E. Cable et al., Estimating Groundwater

Discharge into the Northeastern Gulf of Mexico Using Radon-222, 144 Earth & Planetary

Sci. Letters 591 (1996) ............................................20

vii

TABLE OF AUTHORITIES—Continued

Page

Alida Cantor et al., Navigating GroundwaterSurface Water Interactions Under the Sustainable Groundwater Management Act (2018)............25

John K. Carmichael & Gregory C. Johnson,

Groundwater/Surface-Water Interaction in

Central Sevier County, Tennessee, October

2015–2016 (U.S. Geological Survey Open-File

Report 2017–1147, 2017) ........................................17

Colo. Geological Survey, Ground Water Atlas of

Colorado, http://coloradogeologicalsurvey.org/wpcontent/uploads/wateratlas/chapter2page2.html

(last visited July 8, 2019) ..........................................8

Brewster Conant Jr. et al., A Framework for

Conceptualizing Groundwater-Surface Water

Interactions and Identifying Potential Impacts on Water Quality, Water Quantity, and

Ecosystems, 574 J. Hydrology 609 (2019) .................6

P.G. Cook et al., Determining Natural Groundwater Inﬂux to a Tropical River Using Radon,

Chloroﬂuorocarbons and Ionic Environmental Tracers, 277 J. Hydrology 74 (2003) ..................21

F. Cornaton & P. Perrochet, Groundwater Age,

Life Expectancy and Transit Time Distributions in Advective-Dispersive Systems: 1. Generalized Reservoir Theory, 29 Advances in

Water Resources 1267 (2006) .................................19

viii

TABLE OF AUTHORITIES—Continued

Page

Henry Darcy, Les Fontaines Publiques de la Ville

de Dijon: Exposition et Application des Principes à Suivre et des Formules à Employer

dans les Questions de Distribution d’Eau (Victor Dalmont ed., 1856) ............................................13

Stanley N. Davis et al., Ground‐Water Tracers—

A Short Review, 18 Ground Water 14 (1980) .........18

Kevin F. Dennehy et al., Groundwater Availability in the United States: The Value of Quantitative Regional Assessments, 23 Hydrogeology

J. 1629 (2015) ..........................................................16

K. Devito et al., A Framework for Broad-Scale

Classiﬁcation of Hydrologic Response Units

on the Boreal Plain: Is Topography the Last

Thing to Consider?, 19 Hydrological Processes

1705 (2005) ................................................................6

Emin C. Dogrul et al., Groundwater Modeling in

Support of Water Resources Management and

Planning Under Complex Climate, Regulatory, and Economic Stresses, 8 Water 592

(2016) .......................................................................22

Helmut Elsenbeer et al., Chemical Fingerprints

of Hydrological Compartments and Flow

Paths at La Cuenca, Western Amazonia, 31

Water Resources Res. 3051 (1995) ..........................19

Environmental Tracers in Subsurface Hydrology

(Peter G. Cook & Andrew L. Herczeg eds., 2d

prtg. 2001) ...............................................................20

TABLE OF AUTHORITIES—Continued

Page

J.S. Famiglietti et al., Satellites Measure Recent

Rates of Groundwater Depletion in California’s Central Valley, 38 Geophysical Res. Letters L03403 (2011) ..................................................16

Saber Farhadi et al., An Agent-Based-Nash

Modeling Framework for Sustainable Groundwater Management: A Case Study, 177 Agric.

Water Mgmt. 348 (2016) .........................................16

Fed. Judicial Ctr. & Nat’l Research Council, Reference Manual on Scientiﬁc Evidence (3d ed.

2011) .................................................................... 2, 28

R. Allan Freeze & John A. Cherry, Groundwater

(1979) .........................................................................8

S. Ge & S.M. Gorelick, Groundwater and Surface Water, in 3 Encyclopedia of Atmospheric

Sciences 209 (Gerald R. North et al. eds., 2d

ed. 2015) ..................................................................11

David P. Genereux & Harold F. Hemond, Naturally Occurring Radon 222 as a Tracer for

Streamﬂow Generation: Steady State Methodology and Field Example, 26 Water Resources

Res. 3065 (1990) ......................................................20

Tom Gleeson et al., Water Balance of Global Aquifers Revealed by Groundwater Footprint,

488 Nature 197 (2012) ............................................22

Craig R. Glenn et al., Lahaina Groundwater

Tracer Study—Lahaina, Maui, Hawai‘i, Final

Report (2013) ............................................... 21, 24, 25

TABLE OF AUTHORITIES—Continued

Page

Arlen W. Harbaugh, MODFLOW-2005, The U.S.

Geological Survey Modular Ground-Water

Model—the Ground-Water Flow Process (U.S.

Geological Survey Techniques & Methods 6A16, 2005) ................................................................23

Thomas Harter et al., Adjudicating Groundwater: A Judge’s Guide to Understanding

Groundwater and Modeling (2018) ........................22

Ronald W. Harvey, Microorganisms as Tracers in

Groundwater Injection and Recovery Experiments: A Review, 20 FEMS Microbiology Reviews 461 (1997) ......................................................20

Ahmed Hassan, A Validation Process for the

Groundwater Flow and Transport Model of

the Faultless Nuclear Test at Central Nevada

Test Area (U.S. Dep’t of Energy Pub. No.

45197, 2003) ............................................................25

Ralph C. Heath, Basic Ground-Water Hydrology

(U.S. Geological Survey Water Supply Paper

No. 2220, 10th prtg. 2004).......................................13

Mary C. Hill & Claire R. Tiedeman, Effective

Groundwater Model Calibration: With Analysis of Data, Sensitivities, Predictions, and Uncertainty (2007) .......................................................25

George P. Karatzas, Developments on Modeling

of Groundwater Flow and Contaminant

Transport, 31 Water Resources Mgmt. 3235

(2017) .......................................................................26

TABLE OF AUTHORITIES—Continued

Page

Todd R. Kincaid et al., Quantitative Groundwater Tracing and Effective Numerical Modeling

in Karst: An Example from the Woodville

Karst Plain of North Florida (2012) .......................12

Ute Lauber & Nico Goldscheider, Use of Artiﬁcial and Natural Tracers to Assess Groundwater Transit-Time Distribution and Flow

Systems in a High-Alpine Karst System (Wetterstein Mountains, Germany), 22 Hydrogeology J. 1807 (2014) ....................................................21

S. W. Lohman et al., Deﬁnitions of Selected

Ground-Water Terms—Revisions and Conceptual Reﬁnements (Geological Survey WaterSupply Paper 1988, 5th prtg. 1983) .................... 7, 12

Paulo Lojkasek‐Lima et al., Fingerprinting TCE

in a Bedrock Aquifer Using Compound‐Speciﬁc Isotope Analysis, 50 Ground Water 754

(2012) .......................................................................20

Ursula S. McKnight et al., An Integrated Model

for Assessing the Risk of TCE Groundwater

Contamination to Human Receptors and Surface Water Ecosystems, 36 Ecological Engineering 1126 (2010) ................................................28

James McPhee & William W-G. Yeh, Multiobjective Optimization for Sustainable Groundwater Management in Semiarid Regions, 130 J.

Water Resources Plan. & Mgmt. 490 (2004) ..........16

xii

TABLE OF AUTHORITIES—Continued

Page

Mich. Dep’t of Envtl. Quality, RRD-RESOURCE

MATERIALS-25-2013-01, Groundwater Modeling: Remediation and Redevelopment Division Resource Materials (2014) ...............................22

James A. Miller & Cynthia L. Appel, Segment 3:

Kansas, Missouri, and Nebraska, in U.S. Geological Survey, Ground Water Atlas of the

United States (1997) ...............................................11

Tracie-Lynn Nadeau & Mark Cable Rains, Hydrological Connectivity Between Headwater

Streams and Downstream Waters: How Science Can Inform Policy, 43 J. Am. Water Resources Ass’n 118 (2007) ...........................................7

Klaus K.E. Neuendorf et al., Glossary of Geology

(5th ed. 2005) ...........................................................32

J.R. Nimmo, Porosity and Pore Size Distribution

(Reference Module in Earth Sys. & Envtl.

Scis., 2013) .................................................................8

Richard G. Niswonger & Graham E. Fogg, Inﬂuence of Perched Groundwater on Base Flow, 44

Water Resources Res. W03405 (2008) ......................9

Ohio Envtl. Prot. Agency, Ground Water Flow

and Fate and Transport Modeling, in Technical Guidance Manual for Ground Water Investigations (revision 1, 2007) ................................27

Susan E. Powers et al., The Transport and Fate

of Ethanol and BTEX in Groundwater Contaminated by Gasohol, 31 Critical Reviews in

Envtl. Sci. & Tech. 79 (2001) ...................................27

xiii

TABLE OF AUTHORITIES—Continued

Page

H. Prommer et al., MODFLOW/MT3DMS‐

Based Reactive Multicomponent Transport

Modeling, 41 Ground Water 247 (2003) .................23

Mark Cable Rains et al., The Role of Perched Aquifers in Hydrological Connectivity and Biogeochemical

Processes

Vernal

Pool

Landscapes, Central Valley, California, 20 Hydrological Processes 1157 (2006) ..............................7

William G. Reay et al., Groundwater Discharge

and Its Impact on Surface Water Quality in a

Chesapeake Bay Inlet, 28 Water Resources

Bull. 1121 (1992) .....................................................26

Thomas E. Reilly & Arlen W. Harbaugh, Guidelines for Evaluating Ground-Water Flow Models (U.S. Geological Survey Sci. Investigations

Report 2004-5038, 2004) .........................................25

Paul W. Reimus & Bill W. Arnold, Evaluation of

Multiple Tracer Methods to Estimate Low

Groundwater Flow Velocities, 199 J. Contaminant Hydrology 1 (2017) .........................................18

Kimberly A. Rhodes et al., The Importance of

Bank Storage in Supplying Baseﬂow to Rivers

Flowing Through Compartmentalized, Alluvial Aquifers, 53 Water Resources Res. 10,539

(2017) .......................................................................26

Donald O. Rosenberry et al., Combined Use of

Thermal Methods and Seepage Meters to Efﬁciently Locate, Quantify, and Monitor Focused

Groundwater Discharge to a Sand‐Bed

Stream, 52 Water Resources Res. 4486 (2016) .......15

xiv

TABLE OF AUTHORITIES—Continued

Page

Ward Sanford, Recharge and Groundwater

Models: An Overview, 10 Hydrogeology J. 110

(2002) .......................................................................22

B. R. Scanlon et al., Ground Referencing GRACE

Satellite Estimates of Groundwater Storage

Changes in the California Central Valley, USA,

48 Water Resources Res. W04520 (2012)................. 16

Christina Schornberg et al., Simulating the Effects of Geologic Heterogeneity and Transient

Boundary Conditions on Streambed Temperatures—Implications for Temperature-Based

Water Flux Calculations, 33 Advances in Water Resources 1309 (2010) .......................................20

Daniel T. Snyder, Estimated Depth to Ground

Water and Conﬁguration of the Water Table in

the Portland, Oregon Area (U.S. Geological

Survey Sci. Investigations Report 2008–5059,

2008) ........................................................................11

Claudette Spiteri et al., Modelling the Geochemical Fate and Transport of Wastewater-Derived

Phosphorus in Contrasting Groundwater Systems, 92 J. Contaminant Hydrology 87 (2007) .......27

T.P. Sullivan et al., Nitrate Transport in a Karst

Aquifer: Numerical Model Development and

Source Evaluation, 573 J. Hydrology 432

(2019) .......................................................................28

TABLE OF AUTHORITIES—Continued

Page

Charles J. Taylor & William M. Alley, GroundWater-Level Monitoring and the Importance of

Long-Term Water-Level Data (U.S. Geological

Survey Circular 1217, 2001) ...................................10

Chin-Fu Tsang, The Modeling Process and

Model Validation, 29 Ground Water 825

(1991) .......................................................................25

Univ. of Ariz., Ariz. Geological Survey, Earth

Fissures—Natural Hazards in Arizona Viewer,

http://azgs.arizona.edu/earth-fissures-groundsubsidence/earth-fissures-natural-hazardsarizona-viewer (last visited July 8, 2019) ..............32

U.S. Envtl. Prot. Agency, Citizen’s Guide to

Ground-Water Protection (1990) .............................31

U.S. Geological Survey, Ground Water Atlas of

the United States (James A. Miller ed., 2000) ........16

J. V. Ward, The Four-Dimensional Nature of

Lotic Ecosystems, 8 J. N. Am. Benthological

Soc’y 2 (1989) .............................................................6

Parker J. Wigington et al., Oregon Hydrologic

Landscapes: A Classiﬁcation Framework, 49 J.

Am. Water Resources Ass’n 163 (2013) ....................6

S. Jeffress Williams et al., Surﬁcial Sediment

Character of the New York-New Jersey Offshore Continental Shelf Region: A GIS Compilation (U.S. Geological Survey Open-File

Report 2006–1046, 2007) ..........................................8

xvi

TABLE OF AUTHORITIES—Continued

Page

Thomas C. Winter, The Concept of Hydrologic

Landscapes, 37 J. Am. Water Resources Ass’n

335 (2001) ..................................................................6

Thomas C. Winter et al., Ground Water and Surface Water: A Single Resource (U.S. Geological

Survey Circular 1139, 1999) .....................................5

David M. Wolock et al., Delineation and Evaluation of Hydrologic-Landscape Regions in the

United States Using Geographic Information

System Tools and Multivariate Statistical

Analyses, 34 Envtl. Mgmt. S71 (2004) ......................6

INTERESTS OF AMICI CURIAE1

Amici curiae2 are four scientists and eight national and international scientiﬁc societies, all actively

involved in research, education, and the conservation

and restoration of aquatic ecosystems and resources in

the United States. Amici have an interest in this case

because of its impact on the integrity of those ecosystems and resources. The Clean Water Act’s objective

can only be achieved by considering the science behind

the ways in which groundwater connects point sources

and surface waters.

In accordance with this Court’s Rule 37.3(a), all parties

have provided written consent to the ﬁling of this brief. In a letter

submitted to this Court on April 4, 2019, counsel for respondents

provided blanket consent to the ﬁling of amici curiae briefs in support of either or neither party, ﬁled within the time allowed by

this Court’s rules. Counsel for petitioner provided written consent

to the ﬁling of this brief on July 3, 2019.

Additionally, pursuant to this Court’s Rule 37.6, amici curiae

state that no counsel for a party authored this brief in whole or in

part, that no party or party’s counsel made a monetary contribution intended to fund the preparation or submission of this brief,

and that no person—other than amici curiae, their members, or

their counsel—made a monetary contribution intended to fund

the preparation or submission of this brief.

Amici curiae are Dr. Thomas Harter, Dr. David Kaplan, Dr.

Mark Rains, Dr. Andrew Reeve, American Fisheries Society, Association for the Sciences of Limnology and Oceanography,

Coastal and Estuarine Research Federation, Freshwater Mollusk

Conservation Society, International Association for Great Lakes

Research, Phycological Society of America, Society for Freshwater

Science, and Society of Wetland Scientists. Biographies of the scientists and descriptions of the scientiﬁc societies are provided in

the Appendix to this brief.

The legal and policy decisions at issue in this case

must be based on sound science. As Justice Breyer

noted, “[t]he law must seek decisions that fall within

the boundaries of scientiﬁcally sound knowledge.” Fed.

Judicial Ctr. & Nat’l Research Council, Reference Manual on Scientiﬁc Evidence 4 (3d ed. 2011). Scientists

can measure the interactions between surface waters

and groundwater using robust methods, including

physical measurements, chemical tracers, and computer models. These methods can be used to determine

when point source discharges of pollutants adversely

affect surface waters, including navigable waters, via

groundwater. The Clean Water Act was intended to—

and indeed, must—regulate such point source discharges of pollutants to maintain the chemical, physical, and biological integrity of the Nation’s waters. This

brief highlights the important scientiﬁc reality of the

connections between point sources and surface waters

via different types of groundwater pathways, as well as

the scientiﬁc tools used to ascertain those connections.

------------------------------------------------------------------

SUMMARY OF ARGUMENT

A proper interpretation of the Clean Water Act requires a basic understanding of hydrology, the science

of water on and below the Earth’s surface. Groundwater can connect point sources and surface waters. Thus,

pollutants discharged into groundwater may contaminate surface waters, including navigable waters.

The vast majority of groundwater is stored in

aquifers. Scientists generally classify aquifers as unconﬁned, conﬁned, or perched, depending on the

groundwater’s interaction with subsurface geology.

Groundwater ﬂow through these aquifers varies based

on hydraulic gradient and hydraulic conductivity. Connectivity between groundwater and surface waters is a

function of hydrology, landscape topography, aquifer

conditions, surface water and groundwater management, and climate.

Multiple scientiﬁc methods exist to estimate and

empirically quantify the magnitude and timing of

groundwater connections between point sources and

surface waters. These methods include physical measurements, chemical tracers, and groundwater models.

These methods can also be used to determine if, and to

what extent, pollutants discharged from point sources

contaminate surface waters through groundwater.

The Clean Water Act’s mandate of restoring and

maintaining the chemical, physical, and biological integrity of the Nation’s waters is based on science and

thus can only be achieved through the consideration of

science. Furthermore, Congress’s use of the terms

“well” and “discrete ﬁssure” in the deﬁnition of point

source establishes an intent to regulate discharges

that travel through groundwater; as a scientiﬁc matter

(and as a matter of common sense), wells and ﬁssures

can only discharge into groundwater. The Ninth Circuit’s approach, which considers whether pollutants in

a navigable water are fairly traceable from a point

source, is consistent with the science discussed in this

brief. In contrast, petitioner’s means-of-delivery test

blithely disregards hydrogeologic reality, ignoring the

science behind the connections between point sources

and surface waters through groundwater, as well as established scientiﬁc methods used to track pollutants

through these pathways.

------------------------------------------------------------------

ARGUMENT

Well-established scientiﬁc methods are used to assess whether and how much particular point sources

and surface waters are connected by groundwater. Like

surface water, groundwater occurs in several forms.

The ﬂowpaths of groundwater, including pollutants

contained therein, can be traced through physical

measurements (e.g., groundwater levels, ﬂow meters),

chemical measurements (e.g., forensic analysis of water quality, tracer studies), and numerical modeling

(e.g., USGS MODFLOW). These scientiﬁc methods can

establish the hydrological connection between particular point sources and surface waters via groundwater

(and, in the present case, they were used to conclusively establish the hydrological connection between

the Lahaina Wells and the nearby Paciﬁc coastal waters). The Clean Water Act’s text makes clear that Congress intended the Act to regulate the discharges of

pollutants from point sources when those pollutants

are conveyed via groundwater to surface waters that

are waters of the United States. The Clean Water Act’s

mandate to restore and maintain the chemical, physical, and biological integrity of the Nation’s waters, 33

U.S.C. § 1251(a), can only be met if the scientiﬁc reality

of connections between point sources and surface waters through groundwater is taken into account.

INTRODUCTION TO HYDROLOGIC CONCEPTS AND GROUNDWATER

To understand how groundwater conveys pollutants

from point sources to surface waters, one must understand several basic hydrologic principles. Groundwater

plays an important role in overall surface water quantity and quality. Indeed, groundwater ﬂow signiﬁcantly

contributes to annual streamﬂow. While highly variable across the country, approximately 55% of annual

streamﬂow nationwide is provided by groundwater.

Thomas C. Winter et al., Ground Water and Surface

Water: A Single Resource 12 (U.S. Geological Survey

Circular 1139, 1999). This hydrological connection includes the transfer of anything transported by the

groundwater, such as pollutants. The precise nature of

how groundwater ﬂow can connect a particular point

source to a surface water depends on a variety of factors, but this fact remains unassailable: groundwater

can create a hydrological connection between a

particular point source and a surface water. See generally Brewster Conant Jr. et al., A Framework for Conceptualizing Groundwater-Surface Water Interactions

and Identifying Potential Impacts on Water Quality,

Water Quantity, and Ecosystems, 574 J. Hydrology 609

(2019).

Several factors influence the nature of groundwater connections between point sources and surface

waters. A basic tenet of freshwater ecology is that hydrological connections consist of four dimensions: longitudinal (e.g., along the stream system), lateral (e.g.,

stream-landscape), vertical (e.g., stream-groundwater),

and temporal. J. V. Ward, The Four-Dimensional Nature of Lotic Ecosystems, 8 J. N. Am. Benthological

Soc’y 2, 2–6 (1989). These dimensions operate from local to landscape scales. Id. Fluxes of water along hydrological ﬂowpaths occur at varying frequencies,

magnitudes, timings, durations, and rates, which are

primarily determined by topography, geology, and climate. Thomas C. Winter, The Concept of Hydrologic

Landscapes, 37 J. Am. Water Resources Ass’n 335, 336–

39 (2001); David M. Wolock et al., Delineation and

Evaluation of Hydrologic-Landscape Regions in the

United States Using Geographic Information System

Tools and Multivariate Statistical Analyses, 34 Envtl.

Mgmt. S71, S72–S73, S80–S81 (2004); K. Devito et al.,

A Framework for Broad-Scale Classiﬁcation of Hydrologic Response Units on the Boreal Plain: Is Topography the Last Thing to Consider?, 19 Hydrological

Processes 1705, 1708–11 (2005); Parker J. Wigington et

al., Oregon Hydrologic Landscapes: A Classiﬁcation

Framework, 49 J. Am. Water Resources Ass’n 163, 164,

172 (2013). Collectively, these factors control the physical integrity of downgradient waters. Tracie-Lynn

Nadeau & Mark Cable Rains, Hydrological Connectivity Between Headwater Streams and Downstream Waters: How Science Can Inform Policy, 43 J. Am. Water

Resources Ass’n 118, 122–24 (2007); Mark Cable Rains

et al., The Role of Perched Aquifers in Hydrological

Connectivity and Biogeochemical Processes in Vernal

Pool Landscapes, Central Valley, California, 20 Hydrological Processes 1157, 1157 (2006). In essence, these

factors can shape the ways in which the downgradient

waters are affected by the other waters (including

groundwater) to which they have connections.

A. Groundwater Storage

Groundwater systems have a number of characteristics that affect their storage and ﬂows and thus the

ways in which a particular groundwater system can

convey pollutants from an individual point source to

surface waters. The vast majority of groundwater ﬂow

occurs in aquifers, geological formations made up of

permeable materials (i.e., soil and rock) saturated

with water. S. W. Lohman et al., Deﬁnitions of Selected

Ground-Water Terms—Revisions and Conceptual Reﬁnements 2 (Geological Survey Water-Supply Paper

1988, 5th prtg. 1983). Water in aquifers is stored in

pores and fractures, the spaces between sediment particles and rock surfaces, respectively. The collective behavior of pores or fractures in a soil or rock medium is

referred to as porosity, which is the volume fraction of

pore space relative to the total volume of the medium.

J.R. Nimmo, Porosity and Pore Size Distribution 1–3

(Reference Module in Earth Sys. & Envtl. Scis., 2013).

The soil and rocks that make up aquifers are thus referred to as porous media, and the higher the porosity,

the more water a porous medium can hold.3 The size,

shape, and connectivity of pores within the medium

help deﬁne the aquifer storage capacity, aquifer hydraulic conductivity (rate at which water can move

through the aquifer), and the type and rate of surface

water-groundwater interactions.

In turn, aquifers are classiﬁed into three primary

categories based on their interaction with subsurface

geology: unconﬁned, conﬁned, and perched. Colo. Geological Survey, Ground Water Atlas of Colorado, http://

coloradogeologicalsurvey.org/wp-content/uploads/water

atlas/chapter2page2.html (last visited July 8, 2019);

see also Vedat Batu, Aquifer Hydraulics: A Comprehensive Guide to Hydrogeologic Data Analysis 22–24

(1998). Unconﬁned aquifers (Figure 1), also referred to

as water table aquifers or surﬁcial aquifers, extend

from near the land surface down to some constraining

The porous media that make up aquifers can include unconsolidated (individual) soil particles, ranging in size from sand

grains (approximately 0.1 to 2 mm) to gravel (2 to 64 mm) to large

cobbles and boulders (>64 mm), S. Jeffress Williams et al., Surficial

Sediment Character of the New York-New Jersey Offshore Continental Shelf Region: A GIS Compilation 11–12 (U.S. Geological

Survey Open-File Report 2006-1046, 2007), as well as consolidated porous rocks like sandstone, and fractured porous rocks like

basalt and limestone. R. Allan Freeze & John A. Cherry, Groundwater 152–63 (1979).

geological unit (a low-permeability soil or rock layer,

such as clay or some types of bedrock). Unconﬁned aquifers are closely connected to the land surface and atmosphere, and the level of water in an unconﬁned

aquifer, often referred to as the water table, is the top

of the groundwater system. Conﬁned aquifers (Figure

1) are fully saturated zones that are separated from

the land surface and atmosphere by one or more conﬁning layers or units, which are geological formations

with relatively low hydraulic conductivity (permeability). Because conﬁned aquifers are separated from the

atmosphere, they are often under considerable pressure from water recharging (inﬁltrating into/ﬁlling up)

the aquifer at higher elevations, meaning that water

in a well placed in the conﬁned aquifer will rise above

the conﬁning unit (Figure 1). Finally, perched aquifers

are small and localized mounds of groundwater that

accumulate on top of discontinuous patches of low-permeability geologic units (Figure 2). The volume of water in perched aquifers is generally small and varies

with climate, but they can be important for supporting

groundwater-dependent ecosystems, such as wetlands

and ephemeral streams. Mark M. Brinson, A Hydrogeomorphic Classification for Wetlands 35 (Wetlands

Research Program Tech. Report WRP-DE-4, 1993);

Richard G. Niswonger & Graham E. Fogg, Inﬂuence of

Perched Groundwater on Base Flow, 44 Water Resources Res. W03405, at 1 (2008). Thus, each type of

aquifer can bear a different relationship to surface waters, based on its different interactions with surface topography and subsurface geology.

Figure 1. Cross section of an aquifer system with both

unconfined and confined units. Source: Charles J. Taylor

& William M. Alley, Ground-Water-Level Monitoring

and the Importance of Long-Term Water-Level Data 4

ﬁg.A–2 (U.S. Geological Survey Circular 1217, 2001).

Figure 2. Cross section of an aquifer system with both

unconﬁned and perched units. Source: Daniel T.

Snyder, Estimated Depth to Ground Water and Conﬁguration of the Water Table in the Portland, Oregon Area

4 ﬁg.2 (U.S. Geological Survey Sci. Investigations Report 2008–5059, 2008).

B. Groundwater Flows

The science behind groundwater ﬂows is key to

understanding how groundwater can transport discharges of pollutants from point sources to surface waters. In general, groundwater ﬂow is much slower than

ﬂow in surface water systems. S. Ge & S.M. Gorelick,

Groundwater and Surface Water, in 3 Encyclopedia of

Atmospheric Sciences 209, 210 (Gerald R. North et al.

eds., 2d ed. 2015). For example, groundwater ﬂow in

the High Plains aquifer has been estimated to be about

1 foot (0.3 meters) per day. James A. Miller & Cynthia

L. Appel, Segment 3: Kansas, Missouri, and Nebraska,

in U.S. Geological Survey, Ground Water Atlas of the

United States ch. 730-D, at D13 (1997). This is not the

case, however, for all groundwater systems. Flow velocities in karst (limestone) aquifers and in some volcanic

aquifers, where water is moving through fractures and

conduits, can approach or exceed those in surface water systems. For example, Kincaid et al. observed

groundwater ﬂow velocities of up to 15,000 feet (approximately 4,500 meters) per day. Todd R. Kincaid et

al., Quantitative Groundwater Tracing and Effective

Numerical Modeling in Karst: An Example from the

Woodville Karst Plain of North Florida (2012).

Across all groundwater system types and materials, groundwater ﬂow rates are controlled by two fundamental quantities: hydraulic gradient and hydraulic

conductivity. Hydraulic gradient is the difference in

hydraulic head between two points divided by the distance between them (e.g., the slope of the water table).

Hydraulic head (sometimes referred to as total head)

at any point in a groundwater system is the sum of two

elements: (1) the elevation head, which is equal to the

elevation of the point above a vertical reference datum,

such as mean sea level; and (2) the pressure head,

which is equal to the height of a water that can be supported by the pressure at the point.4 Groundwater

ﬂows from areas of high hydraulic head to areas of low

hydraulic head; critically, this includes ﬂow from

groundwater systems to surface water bodies and vice

versa. Hydraulic conductivity can be thought of as the

ease with which water ﬂows through a porous or

A third component, the velocity head, is extremely small

and usually not taken into account. Lohman et al., supra, at 7.

fractured medium. Ralph C. Heath, Basic Ground-Water Hydrology 10, 12, 25 (U.S. Geological Survey Water

Supply Paper No. 2220, 10th prtg. 2004).

The physical law that describes groundwater ﬂow

is Darcy’s Law, which states that ﬂow through a porous

medium is the mathematical product of the hydraulic

gradient and hydraulic conductivity. Henry Darcy, Les

Fontaines Publiques de la Ville de Dijon: Exposition et

Application des Principes à Suivre et des Formules à

Employer dans les Questions de Distribution d’Eau

(Victor Dalmont ed., 1856). Larger values of hydraulic

gradient or hydraulic conductivity equate directly to

larger groundwater ﬂow volumes and velocities. For

example, if the hydraulic gradient is doubled (i.e., by

increasing the water table slope) and the hydraulic

conductivity stays the same, the groundwater ﬂow rate

will double. Similarly, if the hydraulic conductivity is

halved (i.e., a less transmissive geologic medium), but

the hydraulic gradient remains the same, the groundwater ﬂow rate will be halved. Groundwater ﬂow rates

can be high in areas where the hydraulic gradient, hydraulic conductivity, or both are high.

II.

ROBUST SCIENTIFIC METHODS CAN

MEASURE THE EXTENT TO WHICH

GROUNDWATER

CONNECTS

POINT

SOURCES TO SURFACE WATERS

Hydrogeologists have developed a robust set of

tools for measuring the extent to which point sources

are connected to surface waters through groundwater.

Multiple direct and indirect approaches have been developed to measure groundwater flow speed and direction, surface water-groundwater interactions, and

contaminant transport in the subsurface. These approaches include physical measurements, chemical

tracer methods, and groundwater models. They rely on

ﬁeld, laboratory, or remote sensing measurements, and

on knowledge of the geology, hydrology, land use, and

climate. The choice of measurement will depend on local conditions, funding, available data, and time available for data collection and analysis.5

A. Physical Measurements

First, groundwater connections between a point

source and a surface water can be measured via

physical measurement, the most direct approach to

quantifying groundwater ﬂow speed and direction.

Measuring hydraulic heads in multiple locations allows hydrogeologists to understand general groundwater ﬂow direction (i.e., from areas of high to low head)

and estimate ﬂow rates. Maps of hydraulic heads

across a region are called potentiometric surfaces

(sometimes referred to as piezometric surfaces) and

are analogous to topographic maps, but instead of

Like any tool, each approach is subject to limitations, which

may include time constraints, lack of data, and uncertainty regarding future conditions. See, e.g., Mary P. Anderson et al., Applied Groundwater Modeling: Simulation of Flow and Advective

Transport 11–13 (2d ed. 2015). In such cases, pollutants in a surface water may not be “fairly traceable” to a particular point

source.

illustrating how land surface elevation varies across a

landscape, they show spatial variation in hydraulic

heads of groundwater (Figure 3). Potentiometric maps

are thus useful both for representing spatiotemporal

variation in aquifer storage and for visually illustrating patterns of groundwater ﬂow direction. Difference

in hydraulic heads between points allows for the estimation of groundwater velocity using Darcy’s Law

with information about aquifer hydraulic conductivity

and porosity. Under some circumstances, groundwater

ﬂow speed and direction can also be measured directly

in the aquifer using several different types of groundwater ﬂow meters (e.g., heat-pulse, acoustic Doppler,

and ﬂuid-conductivity) deployed in wells. E.R. Bayless

et al., Accuracy of Flowmeters Measuring Horizontal

Groundwater Flow in an Unconsolidated Aquifer Simulator, 31 Ground Water Monitoring & Remediation

48, 49 (2011); see also Donald O. Rosenberry et al.,

Combined Use of Thermal Methods and Seepage Meters to Efﬁciently Locate, Quantify, and Monitor Focused Groundwater Discharge to a Sand‐Bed Stream,

52 Water Resources Res. 4486 (2016) (use of seepage

meters to quantify groundwater-surface water exchange).

Groundwater storages can be estimated as the

product of aquifer area, speciﬁc yield (the volume of

water that can be pumped out of an aquifer relative to

its total volume), and thickness (the height or length

of the saturated aquifer media); this information

comes from geological surveys, aquifer mapping efforts, and measurements of groundwater levels from

observation and pumping wells. See generally U.S. Geological Survey, Ground Water Atlas of the United

States (James A. Miller ed., 2000); Kevin F. Dennehy et

al., Groundwater Availability in the United States: The

Value of Quantitative Regional Assessments, 23 Hydrogeology J. 1629 (2015). Groundwater storage changes

are typically measured using a network of wells that

track changes in water levels over time. More recently,

satellite-based remote sensing technology has been

used to estimate groundwater storage volumes over

large groundwater basins by detecting changes in

gravity. J.S. Famiglietti et al., Satellites Measure Recent Rates of Groundwater Depletion in California’s

Central Valley, 38 Geophysical Res. Letters L03403, at

1–2 (2011); B. R. Scanlon et al., Ground Referencing

GRACE Satellite Estimates of Groundwater Storage

Changes in the California Central Valley, USA, 48 Water Resources Res. W04520, at 2–5 (2012). Measurements of water levels, hydraulic conductivity, and

estimates of groundwater storage are often coupled

with mathematical models of groundwater hydrology

(discussed infra Section II(C)) to understand changes

over time and guide more sustainable groundwater

management. James McPhee & William W-G. Yeh,

Multiobjective Optimization for Sustainable Groundwater Management in Semiarid Regions, 130 J. Water

Resources Plan. & Mgmt. 490, 491–93 (2004); Saber

Farhadi et al., An Agent-Based-Nash Modeling Framework for Sustainable Groundwater Management: A

Case Study, 177 Agric. Water Mgmt. 348, 350–53

(2016). Critically, groundwater storage is not a static

quantity but a result of the balance of dynamic ﬂows

among atmosphere (precipitation and evapotranspiration), surface waters (lakes, rivers, and oceans), and

groundwater systems.

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Base from National Geographic Society, 2013

EXPLANATION

Whirlpool

1,013

1.82

Well location, number, and waterlevel altitude, in feet (see table 3)

Surface-water site, number, and

streamflow value, in cubic

feet per second (see table 2)

1,075

2 MILES

2 KILOMETERS

Potentiometric contour—Shows altitude

at which water level would have stood

in tightly cased wells. Dashed where

approximately located. Hachure indicates

depression. Contour interval is 25 feet.

Datum is National Geodetic Vertical Datum

of 1929 (NGVD 29)

Figure 3. Potentiometric surface showing contour

lines (lines of equal hydraulic head), from which ﬂow

direction (from high to low head) can be derived.

Adapted from: John K. Carmichael & Gregory C. Johnson, Groundwater/Surface-Water Interaction in Central Sevier County, Tennessee, October 2015–2016, at 18

ﬁg.7 (U.S. Geological Survey Open-File Report 2017–

1147, 2017).

B. Chemical Tracer Methods

Next, hydrogeologists can use various chemical

tracer methods to derive additional detailed information about groundwater ﬂow and thus the hydrological connection between a particular point source and

surface waters. These types of measurements can be

subdivided into two categories: artiﬁcial and natural,

both of which can be useful for quantifying surface water-groundwater interactions. Ross Brodie et al., An

Overview of Tools for Assessing Groundwater-Surface

Water Connectivity 86–90, 95–98 (2007). Artiﬁcial

tracer studies consist of injecting a conservative solute

(e.g., a salt, dye, or dissolved gas that does not react or

bind to the aquifer material) into the aquifer in one location and measuring tracer concentrations over time

in the groundwater at downgradient (downhill) wells.

Stanley N. Davis et al., Ground‐Water Tracers—A

Short Review, 18 Ground Water 14, 14 (1980). Because

they are non-reactive, injected tracers move with the

water, allowing for the mapping of ﬂow paths and calculation of groundwater ﬂow speed (i.e., the time from

injection at one point to detection at another, divided

by the distance between them). Tracer studies are

widely applied to conﬁrm ﬂow directions and speeds

inferred from measured hydraulic heads, see, e.g., Paul

W. Reimus & Bill W. Arnold, Evaluation of Multiple

Tracer Methods to Estimate Low Groundwater Flow

Velocities, 199 J. Contaminant Hydrology 1 (2017), and

are especially useful for mapping speciﬁc ﬂow paths,

Douglas A. Burns & Long Nguyen, Nitrate Movement

and Removal Along a Shallow Groundwater Flow Path

in a Riparian Wetland Within a Sheep‐Grazed Pastoral

Catchment: Results of a Tracer Study, 36 N.Z. J. Marine

& Freshwater Res. 371, 376–80 (2002). Importantly, artiﬁcial tracer methods characterize both the average

and variation in groundwater ﬂow speed, since groundwater in the same aquifer can move at vastly different

speeds (i.e., quickly through large pores or conduits

and slowly through small pores and consolidated rock).

This variation in ﬂow speed is referred to as velocity

distribution but is often reported in terms of the inverse, called residence time distribution, which quantiﬁes the range of times that groundwater remains in

a particular section of the aquifer. F. Cornaton & P. Perrochet, Groundwater Age, Life Expectancy and Transit

Time Distributions in Advective-Dispersive Systems: 1.

Generalized Reservoir Theory, 29 Advances in Water

Resources 1267, 1269 (2006). Put simply: high velocity

means low residence time and vice versa.

In contrast to artiﬁcial tracer methods, natural

tracer methods use naturally occurring water quality

properties of surface waters and/or groundwater to

understand water sources, travel paths, and interactions. Helmut Elsenbeer et al., Chemical Fingerprints

of Hydrological Compartments and Flow Paths at La

Cuenca, Western Amazonia, 31 Water Resources Res.

3051 (1995). Natural tracer studies are sometimes referred to as “ﬁngerprinting” since they seek to use

unique physical, chemical, or biological “ﬁngerprints”

or “signatures” of particular water types. Id. Some

studies also use the term “fingerprinting” when looking to identify waters contaminated with speciﬁc

wastes. See, e.g., Paulo Lojkasek‐Lima et al., Fingerprinting TCE in a Bedrock Aquifer Using Compound‐

Speciﬁc Isotope Analysis, 50 Ground Water 754 (2012).

Some common natural tracers include heat, Mary P.

Anderson, Heat as a Ground Water Tracer, 43 Ground

Water 951 (2005); dissolved solutes and isotopes, Environmental Tracers in Subsurface Hydrology 2–5 (Peter

G. Cook & Andrew L. Herczeg eds., 2d prtg. 2001); atmospheric gases, Sebastian Bauer et al., A MultiTracer Study in a Shallow Aquifer Using Age Dating

Tracers 3H, 85Kr, CFC-113 and SF6—Indication for Retarded Transport of CFC-113, 248 J. Hydrology 14, 23–

26 (2001); and even microorganisms, Ronald W. Harvey, Microorganisms as Tracers in Groundwater Injection and Recovery Experiments: A Review, 20 FEMS

Microbiology Reviews 461, 463–67 (1997). Natural

tracers can be particularly useful for surveying surface

water-groundwater interactions. Brodie et al., supra,

at 86–90; see, e.g., David P. Genereux & Harold F.

Hemond, Naturally Occurring Radon 222 as a Tracer

for Streamﬂow Generation: Steady State Methodology

and Field Example, 26 Water Resources Res. 3065,

3066–67 (1990) (use of the radon-222 isotope for quantifying streamflow generation from groundwater);

Jaye E. Cable et al., Estimating Groundwater Discharge into the Northeastern Gulf of Mexico Using

Radon-222, 144 Earth & Planetary Sci. Letters 591,

592–93 (1996) (use of the radon-222 isotope for quantifying submarine groundwater ﬂow to the coast);

Christina Schornberg et al., Simulating the Effects of

Geologic Heterogeneity and Transient Boundary Conditions on Streambed Temperatures—Implications for

Temperature-Based Water Flux Calculations, 33 Advances in Water Resources 1309, 1311–13 (2010) (use

of temperature-based measurements of surface watergroundwater interactions in streams); P.G. Cook et al.,

Determining Natural Groundwater Inﬂux to a Tropical

River Using Radon, Chloroﬂuorocarbons and Ionic Environmental Tracers, 277 J. Hydrology 74, 78 (2003)

(combining radon, chloroﬂuorocarbons, and dissolved

ions to estimate groundwater inﬂux to a tropical river).

Finally, natural and artiﬁcial tracer methods are sometimes combined to elucidate different components of

groundwater ﬂow. Ute Lauber & Nico Goldscheider,

Use of Artiﬁcial and Natural Tracers to Assess Groundwater Transit-Time Distribution and Flow Systems in

a High-Alpine Karst System (Wetterstein Mountains,

Germany), 22 Hydrogeology J. 1807, 1811–13 (2014).

In the present case, a multi-faceted study was

conducted by researchers from the U.S. Environmental

Protection Agency, the Hawai‘i Department of Health,

the U.S. Army Engineer Research and Development

Center, and the University of Hawai‘i. Part of the study

involved using a ﬂuorescent tracer dye, which was

added to the efﬂuent before it was injected into the

Lahaina Wells. Craig R. Glenn et al., Lahaina Groundwater Tracer Study—Lahaina, Maui, Hawai’i, Final

Report 4-1 (2013) [hereinafter Glenn et al., Lahaina

Study]. The study found “a hydrogeologic connection”

between the Lahaina injection wells “and the nearby

coastal waters of West Maui.” Pet. App. 9 (internal quotation marks omitted); Glenn et al., Lahaina Study, supra, at ES-3. The study was conducted using methods

consistent with the principles described in this brief

and was an application of sound science.

C. Groundwater Models

Both physical and chemical measurements of

groundwater storage and ﬂow are often coupled with

groundwater models to understand groundwater ﬂow

systems and predict how they will change under different conditions. Mich. Dep’t of Envtl. Quality, RRDRESOURCE MATERIALS-25-2013-01, Groundwater

Modeling: Remediation and Redevelopment Division

Resource Materials 14–15 (2014). Groundwater models

provide tools to determine the manner by and degree

to which point source pollution would be conveyed to

a surface water. See generally Thomas Harter et al.,

Adjudicating Groundwater: A Judge’s Guide to Understanding Groundwater and Modeling (2018). There are

many types of groundwater models, see Ward Sanford,

Recharge and Groundwater Models: An Overview, 10

Hydrogeology J. 110 (2002), but all apply Darcy’s

Law and the principle of the water balance concept6 to

mathematically represent groundwater storage changes

and ﬂows in a speciﬁc place over a speciﬁed time

period, see, e.g., Emin C. Dogrul et al., Groundwater

Modeling in Support of Water Resources Management

and Planning Under Complex Climate, Regulatory,

The volume of water in an aquifer at any time is driven by

the water balance, or the sum of all water inﬂows and outﬂows,

including inﬂows from and outﬂows to surface waters. Tom

Gleeson et al., Water Balance of Global Aquifers Revealed by

Groundwater Footprint, 488 Nature 197, 197 (2012).

and Economic Stresses, 8 Water 592 (2016) (applying

model to simulate groundwater and surface water

flow dynamics within the California Central Valley).

Groundwater models can be coupled with transport

models to simulate the movement of reactive and nonreactive solutes (such as contaminants) through the

aquifer.

The most common groundwater modeling tools,

particularly in the applied setting, are numerical

groundwater models, such as the USGS MODFLOW

model, Arlen W. Harbaugh, MODFLOW-2005, The U.S.

Geological Survey Modular Ground-Water Model—the

Ground-Water Flow Process (U.S. Geological Survey

Techniques & Methods 6-A16, 2005), which is often coupled with the MT3DMS groundwater transport model,

H. Prommer et al., MODFLOW/MT3DMS‐Based Reactive Multicomponent Transport Modeling, 41 Ground

Water 247 (2003). Numerical groundwater models represent the groundwater system through a network or

grid of cells (small elements or grid blocks), each of

which represents the aquifer properties and hydraulic

head in that location (similar to a TV monitor that represents an image through a large number of discrete

pixels, each with one speciﬁc color). Each groundwater

model cell interacts with neighboring cells such that

water and associated solutes ﬂow from cells with high

head to those with low head (consistent with physical

laws). Model cells extend laterally and vertically to a

speciﬁed model boundary. Such groundwater modeling

was used in the Lahaina Study to aid in the design of

the tracer test by estimating the dilution of the dye

during the test and the time it would take for the dye

to appear in the ocean. The Lahaina model incorporated the USGS MODFLOW model and MT3DMS

groundwater transport model, as well as the MODPATH transport model, to track the movement of particles and to simulate the transport of the dyes. Glenn

et al., Lahaina Study, supra, at ES-18–ES-19.

Developing a spatially distributed groundwater

model generally requires at least three sources of

information: (1) spatial variation in aquifer hydrogeological characteristics (e.g., porosity, speciﬁc yield, hydraulic conductivity); (2) information or assumptions

about model boundary conditions (known or assumed

aquifer heads or ﬂows and solute concentrations at the

model boundary); and (3) climate/weather data that,

together with information about land cover, drive aquifer recharge. Depending on the speciﬁc application,

information about groundwater pumping for human

use and surface water-groundwater interactions also

may be important. The groundwater model uses this

information to solve for hydraulic heads within each

cell.7 Model outputs can include time series of hydraulic heads at any or all locations in the aquifer system,

spatiotemporal variation in groundwater ﬂow speed

and direction, and the speed and magnitude of any

solute transport.

To solve numerically, groundwater models use a groundwater ﬂow equation (a water balance based on Darcy’s Law over

a speciﬁed time step (e.g., hourly, daily, monthly)) and a groundwater transport equation over the timeline of the model run (the

temporal duration of the model).

Model simulations are most often compared to

observations (i.e., data) to determine how well the

model represents the real world. Most often, models go

through an iterative process of model calibration and

validation, which consists of adjusting model parameters within their uncertainty limits until model outputs best match observed data. Thomas E. Reilly &

Arlen W. Harbaugh, Guidelines for Evaluating GroundWater Flow Models 23–24 (U.S. Geological Survey Sci.

Investigations Report 2004–5038, 2004); Mary C. Hill

& Claire R. Tiedeman, Effective Groundwater Model

Calibration: With Analysis of Data, Sensitivities, Predictions, and Uncertainty 213–27 (2007). Just as there

are many types of groundwater models, there are many

model calibration and validation approaches and techniques. Chin-Fu Tsang, The Modeling Process and

Model Validation, 29 Ground Water 825, 829 (1991);

Ahmed Hassan, A Validation Process for the Groundwater Flow and Transport Model of the Faultless Nuclear Test at Central Nevada Test Area 8–17 (U.S. Dep’t

of Energy Pub. No. 45197, 2003).8

Once calibrated and validated, groundwater

models can be used for a variety of applications, including quantifying surface water-groundwater interactions. Alida Cantor et al., Navigating GroundwaterSurface Water Interactions Under the Sustainable

The Lahaina model, for example, was calibrated and modiﬁed using actual tracer data. The Lahaina model was then used

to test various hydrogeologic processes to determine which processes may have been affecting the transport of the tracer dye.

Glenn et al., Lahaina Study, supra, at ES-18–ES-19.

Groundwater Management Act 8–10 (2018) (discussing tools and methods for monitoring and measuring

surface water-groundwater dynamics); Kimberly A.

Rhodes et al., The Importance of Bank Storage in Supplying Baseﬂow to Rivers Flowing Through Compartmentalized, Alluvial Aquifers, 53 Water Resources

Res. 10,539, 10,551–54 (2017) (examining interaction

of Brazos River Alluvium Aquifer and Brazos River).

Additionally, as explained below, models can be used

to estimate where and how quickly pollutants will

flow through groundwater systems. See, e.g., Anderson

et al., supra; George P. Karatzas, Developments on

Modeling of Groundwater Flow and Contaminant

Transport, 31 Water Resources Mgmt. 3235 (2017).

D. Applying Robust Scientiﬁc Methods to

Track Pollutants in Groundwater

The groundwater measurement and modeling

tools described above can be used to track pollutants

as they ﬂow though groundwater systems and interact

with surface water bodies. William G. Reay et al.,

Groundwater Discharge and Its Impact on Surface Water Quality in a Chesapeake Bay Inlet, 28 Water Resources Bull. 1121, 1122 (1992). This process is often

referred to as contaminant fate and transport modeling, where fate refers to any alteration of contaminants

via chemical or biological processes and transport refers to movement of contaminants with groundwater

ﬂow. Contaminant fate and transport are generally

modeled using a calibrated groundwater ﬂow model

(like those described above), but they can also be

modeled using measurements of ﬂow velocity if they

are available from physical measurements or tracer

studies. Ohio Envtl. Prot. Agency, Ground Water Flow

and Fate and Transport Modeling, in Technical Guidance Manual for Ground Water Investigations 14-25

to 14-26 (revision 1, 2007). Contaminant fate and

transport models generally simulate the following:

(1) movement of contaminants by advection (ﬂow) and

dispersion (spreading due to velocity variation and

concentration differences); (2) sorption and desorption

(attachment and release) of contaminants from aquifer

materials; and (3) contaminant transformations due to

biological processes (e.g., microbial degradation) or

chemical reactions (e.g., oxidation-reduction reactions).

Id. at 14-3.

As with groundwater ﬂow models, groundwater

fate and transport models are calibrated and validated using measured data. Once calibrated, they

can be used to predict the magnitude and timing of

contaminant ﬂow between different aquifer regions,

see Susan E. Powers et al., The Transport and Fate of

Ethanol and BTEX in Groundwater Contaminated

by Gasohol, 31 Critical Reviews in Envtl. Sci. &

Tech. 79, 114–15 (2001); Claudette Spiteri et al.,

Modelling the Geochemical Fate and Transport of

Wastewater-Derived Phosphorus in Contrasting

Groundwater Systems, 92 J. Contaminant Hydrology

87, 105–06 (2007), as well as to simulate the

transport of contaminants through groundwater to

surface water systems. For example, McKnight et al.

developed a groundwater fate and transport model for

a trichloroethylene (TCE)-contaminated groundwater

plume discharging to a stream and found that, without

cleanup, TCE would be discharging from the groundwater to the stream for multiple decades. Ursula S.

McKnight et al., An Integrated Model for Assessing the

Risk of TCE Groundwater Contamination to Human

Receptors and Surface Water Ecosystems, 36 Ecological Engineering 1126, 1136 (2010). In a recent study,

Sullivan et al. simulated nitrate transport through a

karst aquifer, finding that anthropogenic sources such

as fertilizers and wastewater applied to the land

surface were primary sources of contamination to the

aquifer and associated surface water springs. T.P.

Sullivan et al., Nitrate Transport in a Karst Aquifer:

Numerical Model Development and Source Evaluation,

573 J. Hydrology 432, 446 (2019).

III. THE CLEAN WATER ACT REQUIRES THE

CONSIDERATION OF THE SCIENCE REGARDING GROUNDWATER AND SURFACE WATER CONNECTIONS

While the degree of hydrological connectivity may

be a function of a variety of factors, the measurement

and ﬂow of groundwater to surface waters can be scientiﬁcally ascertained as described above. As Justice

Breyer observed, “[judicial] decisions should reﬂect a

proper scientiﬁc and technical understanding so that

the law can respond to the needs of the public.” Fed.

Judicial Ctr. & Nat’l Research Council, supra, at 2.

Thus, when a pollutant discharges to a navigable

water via a scientiﬁcally ascertained groundwater

connection, the Clean Water Act requires a permit for

that discharge. See 33 U.S.C. §§ 1311(a), 1342(a). Indeed, the mandate of the Clean Water Act—to restore

and maintain the chemical, physical, and biological integrity of the Nation’s waters—can only be met by taking into account the above-described scientiﬁc reality

of the hydrological connection between surface waters

and groundwater, including the conveyance of pollutants.

A. The Clean Water Act Requires Consideration of Science to Meet Its Objective

Science is critically important to make the necessary empirical determinations about the chemical,

physical, and biological integrity of our waters to

achieve the Clean Water Act’s objective. This Court has

noted that the Act “incorporated a broad, systemic

view of the goal of maintaining and improving water

quality: as the House Report on the legislation put it,

‘the word “integrity” . . . refers to a condition in which

the natural structure and function of ecosystems [are]

maintained.’ ” United States v. Riverside Bayview

Homes, Inc., 474 U.S. 121, 132 (1985) (citing H.R. Rep.

No. 92-911, at 76 (1972)). The scientiﬁc principles and

methods described in this brief are routinely used to

empirically track contaminants and assess water quality.

Courts regularly rely on physical measurements,

chemical tracer methods, and groundwater modeling

in Clean Water Act cases. See, e.g., Assateague

Coastkeeper v. Alan & Kristin Hudson Farm, 727

F. Supp. 2d 433, 439 (D. Md. 2010) (relying on piezometers to show that concentrated animal feeding operation was source of pollution); Cmty. Ass’n for the

Restoration of the Env’t v. Nelson Faria Dairy, Inc., No.

CV-04-3060-LRS, 2011 WL 6934707, at *9–10 (E.D.

Wash. Dec. 30, 2011) (relying on groundwater monitoring wells to show that manure management practices

were source of pollution); United States v. Donovan,

661 F.3d 174, 186–88 (3d Cir. 2011) (upholding grant of

summary judgment where scientiﬁc evidence, including dye tracer studies showing hydrological connection, established Clean Water Act violations); United

States v. Acquest Transit LLC, No. 09-CV-00055S(F),

2018 WL 3861612, at *17–19 (W.D.N.Y. Aug. 14, 2018)

(denying motion to preclude dye-tracer study); Greater

Yellowstone Coal. v. Larson, 641 F. Supp. 2d 1120, 1139

(D. Idaho 2009) (holding that no Clean Water Act section 401 certiﬁcation is required when “modeling predicted that it would take between 60 and 420 years for

peak concentrations of selenium to arrive at the surface waters” and the concentrations would not exceed

acceptable limits). Indeed, this Court has deferred to

agency judgments when agencies base their decisions

on sound science. See, e.g., Baltimore Gas & Elec. Co. v.

Nat. Res. Def. Council, Inc., 462 U.S. 87, 103 (1983).9

Rules, however, that ignore science run counter to the objectives of the Clean Water Act and should not be given deference.

In 2016, the EPA submitted an amicus brief to the Ninth Circuit,

siding with the environmental groups in the instant action, acknowledging that the Lahaina Study had determined that a direct hydrological connection existed between the Lahaina Wells

B. Congress’s Inclusion of the Terms “Well”

and “Discrete Fissure” in the Deﬁnition

of Point Source Demonstrates Its Intent

that the Clean Water Act Regulates Discharges of Pollutants to Groundwater

The fact that Congress included the terms “well”

and “discrete ﬁssure” in the deﬁnition of point source

cannot be ignored. A cardinal rule of statutory interpretation is that it is a court’s “duty to give effect, if

possible, to every clause and word of a statute.” Duncan v. Walker, 533 U.S. 167, 174 (2001) (citations and

internal quotation marks omitted). Courts “are thus

‘reluctan[t] to treat statutory terms as surplusage’

in any setting.” Id. (alteration in original) (quoting

Babbitt v. Sweet Home Chapter of Communities for a

Great Or., 515 U.S. 687, 698 (1995)); see also United

States v. Jicarilla Apache Nation, 564 U.S. 162, 185

(2011). The Clean Water Act deﬁnes a “point source” as

and the ocean, and consequently arguing the wells should be regulated under the Clean Water Act. Br. United States as Amicus

Curiae in Supp. of Pls.-Appellees 27–32, May 31, 2016, No. 1517447. The EPA’s brief acknowledged and was supported by

sound science. In a 180-degree reversal, the EPA issued its April

2019 Interpretive Statement that categorically excludes all discharges to groundwater from the NPDES permit program. See

U.S. Envtl. Prot. Agency, Interpretive Statement on Application

of the Clean Water Act National Pollutant Discharge Elimination

System Program to Releases of Pollutants from a Point Source to

Groundwater, 84 Fed. Reg. 16,810, 16,810 (Apr. 23, 2019). This

statement is bereft of any scientiﬁc analysis, referring only to a

nearly three-decades-old EPA publication, U.S. Envtl. Prot.

Agency, Citizen’s Guide to Ground-Water Protection (1990). Accordingly, the statement should be afforded no deference. Cf. Br.

Resp’ts 42, July 12, 2019 (explaining why the Interpretive Statement should not receive Chevron deference).

any discernible, conﬁned and discrete conveyance, including but not limited to any pipe,

ditch, channel, tunnel, conduit, well, discrete

ﬁssure, container, rolling stock, concentrated

animal feeding operation, or vessel or other

ﬂoating craft, from which pollutants are or

may be discharged.

33 U.S.C. § 1362(14) (emphasis added). A “well” in this

context includes injection wells, such as those at issue

in this case, which are expressly used to dispose of

waste. Geologists deﬁne deep-well injection or disposal

as “[d]isposal of liquid waste by injection into wells,

usually constructed especially for the purpose, that

penetrate deep, porous and permeable formations that

are conﬁned vertically by relatively impermeable

beds.” Klaus K.E. Neuendorf et al., Glossary of Geology

167 (5th ed. 2005). A “ﬁssure” is a geologic term meaning a “surface of fracture or a crack in a rock along

which there is a distinct separation.” Id. at 239. As a

scientiﬁc matter, indeed as a matter of common sense,

pollutants from these types of point sources can only

discharge into groundwater. As the Arizona Geological

Survey notes, “ﬁssures are a direct path to the groundwater table, so pollutants and contaminants could potentially ﬂush down the ﬁssure into a groundwater

aquifer.” Univ. of Ariz., Ariz. Geological Survey, Earth

Fissures—Natural Hazards in Arizona Viewer, http://

azgs.arizona.edu/earth-fissures-ground-subsidence/

earth-fissures-natural-hazards-arizona-viewer (last visited July 8, 2019).

Many of the briefs in the instant case supporting

petitioner and opposing Clean Water Act regulation do

not even touch on the fact that wells and discrete ﬁssures are explicitly listed as point sources. Petitioner’s

means-of-delivery test conveniently ignores the inclusion of “well” and “discrete ﬁssure” in the deﬁnition of

point source. There is simply no logical explanation offered for why Congress included terms like “well” and

“discrete ﬁssure” if it did not intend to regulate discharge from those point sources that make their way

to navigable surface waters through groundwater.10

Furthermore, the legislative history of the Safe

Drinking Water Act (“SDWA”), 42 U.S.C. § 300f et seq.,

strongly indicates that Congress understood that certain discharges of pollutants to groundwater were already regulated under the Clean Water Act. A report

from the House of Representatives explained that a

primary reason for enacting the SDWA was because “it

appears that the Federal Water Pollution Control Act

[later, Clean Water Act] may not authorize any regulation of deep well injection of wastes which is not carried out in conjunction with a discharge into navigable

While much is made of Congress’s rejection of the so-called

Aspin Amendment, which called for regulating all groundwater

(see, e.g., Br. United States as Amicus Curiae Supporting Pet’r

27–28, May 16, 2019; Br. Amicus Curiae for Agricultural Business Organizations Supporting Pet’r 19, May 15, 2019), these arguments fail to take into account Aspin’s full speech, which makes

clear that, at a bare minimum, all injection wells were meant to

be fully regulated under the Clean Water Act, with a limited exception for wells used by the oil industry. 1 Cong. Research Serv.,

A Legislative History of the Water Pollution Control Act Amendments of 1972, at 589–90 (1973).

waters.” H.R. Rep. No. 93-1185, at 4 (1974) (emphasis

added) (citing U.S. Envtl. Prot. Agency, Op. of Acting

Deputy Gen. Counsel No. 590 (Dec. 13, 1973)). The

clear inference taken from this report is that at the

time the SDWA was enacted, Congress understood the

Clean Water Act to cover groundwater that ﬂows into

navigable waters.

C. The Science Behind the Hydrological

Connectivity of Groundwater and Surface Waters Supports the Ninth Circuit’s

Fairly Traceable Test, Whereas the Petitioner’s Means-of-Delivery Test Is Not

Workable and Is Not Supported by Science

The approach taken by the Ninth Circuit—one

that considers whether the pollutants in a navigable

water are fairly traceable from a point source—is consistent with the science discussed in this brief. This approach recognizes the intrinsic connections between

surface waters and groundwater, and it recognizes that

scientists have developed robust methods to measure

groundwater ﬂow and track contaminants. In some

cases, like the one currently before this Court, because

of the hydrological connection, a discharge of a pollutant to groundwater is the functional equivalent of a

discharge into the navigable water.

In contrast, the petitioner’s means-of-delivery test

blithely disregards hydrogeologic reality. It ignores all

surface water and groundwater connections, as well as

the scientiﬁc methods used to track pollutants. Such a

simplistic interpretation of the Clean Water Act is inconsistent with Congress’s intent (as evinced by the

use of the terms “well” and “discrete ﬁssure” in the definition of point source) and the overall purpose of the

Act.

Several briefs in the instant case erroneously suggest that the fairly traceable test offers no logical stopping point. There are, however, at least three such

limiting principles. First, the test itself articulates a

limiting principle. The scientiﬁc methods used to

measure groundwater ﬂow and track pollutants—

physical measurements, chemical tracers, and groundwater modeling—may not be able to “fairly trace” a

surface water pollutant back to a particular point

source due to time, data, or other constraints. See supra note 5. Second, the scientiﬁc methods may show

that the particular point source is not or is not projected to be the source of surface water contaminants.

See Greater Yellowstone Coal., 641 F. Supp. 2d at 1139.

Third, the principle of proximate cause may serve as a

limiting principle. Babbitt, 515 U.S. at 709 (O’Connor,

J., concurring) (noting that Endangered Species Act

regulation “is limited by ordinary principles of proximate causation, which introduce notions of foreseeability”). Accordingly, even if a scientiﬁc method does

establish that it is more likely than not that a particular point source is the cause in fact of the pollution, a

court may decide that the connection is too remote in

time or distance to warrant Clean Water Act regulation. In the instant case, however, the scientiﬁc methods used conclusively established that the Lahaina

Wells are the source of pollution in the nearby Paciﬁc

coastal waters.

------------------------------------------------------------------

CONCLUSION

The Clean Water Act’s mandate can only be met

by considering science, which can be used to assess the

extent to which point sources are connected to surface

waters through groundwater. The Ninth Circuit’s

fairly traceable test reflects the scientific reality of

surface water-groundwater connections. Accordingly,

amici curiae respectfully request that this Court afﬁrm

the Ninth Circuit’s decision.

Respectfully submitted,

DR. STEPH TAI

UNIVERSITY OF WISCONSIN

LAW SCHOOL

975 Bascom Mall

Madison, WI 57306

202-270-8926

CHRISTOPHER W. GREER

WHITE & CASE LLP

1221 Avenue of the Americas

New York, NY 10020

212-819-2593

ROYAL C. GARDNER

Attorney of Record

ERIN OKUNO

KATHLEEN E. GARDNER

STETSON UNIVERSITY

COLLEGE OF LAW

INSTITUTE FOR BIODIVERSITY

LAW AND POLICY

1401 61st Street South

Gulfport, FL 33707

gardner@law.stetson.edu

727-562-7864

This is a copy of a public record, reproduced as it was published. It is not legal advice, and it may not be the version a court would rely on. Check the official source before you cite it.