EXPLANATIONPredicted arsenic concentrations, micrograms per liter

Less than 1.0

1.0 to 1.9

2.0 to 2.9

3.0 to 4.9

5.0 to 9.9

10 to 24

Equal to or greater than 25

Arsenic Predictions

Observed arsenic concentration, micrograms per literLess than 1.0

1.0 to 1.9

2.0 to 2.9

3.0 to 4.9

5.0 to 9.9

10 to 24

Equal to or greater than 25

EXPLANATIONArsenic Training Observations

EXPLANATIONHydrogeologic area boundary—Names of

the hydrogeologic areas are shown on the online version of this plate available at http://pubs.usgs.gov/sim/3234/

Hydrogeologic areas

TrinityTrinity

RiverRiver

Eel RiverEel River

RussianRussian

RiverRiver

RiverRiver

Sacramento

Sacramento

Feath

er Ri

ver

Feath

er Ri

ver

NorthNorthYubaYuba River

River

American RiverAmerican River

RiverRiver

MokelumneMokelumne

RiverRiverAmericanAmerican

North

For

k

North

For

k

RiverRiverTuolumneTuolumne

MercedMerced

RiverRiver

RiverRiver

San JoaquinSan Joaquin

RiverRiver

Joaquin

Joaquin

SanSan

River

River

KingsKings

Salinas River

Salinas River

Kern River

Kern River

Quin

n Rive

r

Quin

n Rive

r

RiverRiver

Humboldt

Humboldt

Rees

e Riv

er

Rees

e Riv

er

Sevier R

iver

Sevier R

iver

Rive

rRi

ver

Bear

Bear

Jordan RiverJordan River

Mea

dow

Valle

y

Mea

dow

Valle

yWa

shWa

sh

White River

White River

Pahranagat Wash

Pahranagat Wash

Muddy

RiverM

uddy

River

Amaragosa

Amaragosa

RiverRiver

Verde River

Verde River

Salt RiverSalt River

Colorado

Colorado

RiverRiver

RiverRiverGilaGila

RiverRiverMojaveMojave

Rio GrandeRio Grande

ChamaChama

RioRio

PuercoPuerco

RioRio

Owens River

Owens River

GrandeGrande

RioRio

Great Salt Lake

Great Salt Lake

WalkerLakeWalkerLake

PyramidLakePyramidLake

Rye PatchReservoirRye PatchReservoir

LakeTahoeLakeTahoe

WalkerWalker

RiverRiver

LakeMeadLakeMead

LakeMohaveLakeMohave

SmithRiverBasin

KlamathBasin

ScottRiverBasin

ShastaValley

Trinity-SalmonBasin

ShastaLake Area

Mad-Redwood

Basin

MattoleRiverBasin

LowerPit River

Basin

ButteCreekBasin

EelRiverBasin

NorthernCoastalBasins

UkiahValley

SacramentoValley

Upper CacheCreek Basin

Santa RosaValley

Upper PutahCreek Basin

NapaValleyBodega

Basin

PetalumaValley

SonomaValley Suisun-

FairfieldValley

SmithValley

MasonValley

CarsonValley

TahoeValley

SantaRosa

Valley

EagleValley

WashoeValley Dayton

Valley

ChurchillValley

TruckeeRiver Basin-

Tracy SegmentTruckee

RiverBasin-

Reno/SparksSegment

LemmonValley

SpanishSpringsValley

TruckeeRiver Basin-Dodge Flat

Lost RiverBasin

Upper PitRiver Basin

LakeAlmanorValley

IndianValley

UpperSusanRiver

and EagleLake

Valley

SierraValley

CarsonDesert

FernleyArea

WarmSpringsValley

LongValley

PyramidLake

Valley

HoneyLake

Valley

Willow Creekand Horse

Lake Valleys

SmokeCreekDesert

SanEmidioDesert Kumiva

Valley

WinnemuccaLake

Valley

GraniteSpringsValley

HumboldtRiverBasin-

LovelockSegment

Madeline Plains

Duck LakeValley Hualapi

Flat

BlackRockDesert

HumboldtRiver Basin-

Imlay Segment

GooseLake

Valley

SurpriseValley

LongValley

MassacreLake

Valley

SwanLake

Valley

High RockLake Valley

MudMeadow

CreekBasin

VirginValley

SummitLake

Valley

GridleyLake

Valley

ContinentalLake

Valley

PineForestValley

Kings Riverand Desert

Valleys

IoneValley

GabbsValley

East SodaSpringValley

WestSoda

SpringValley

WalkerLake

Valley

East WalkerRiver Basin

AntelopeValley

DixieValley

FairviewValley

StingareeValley

SmithCreekValley

EdwardsCreekValley

BuenaVista

Valley

Silver Stateand Quinn

River Valleys

GrassValley

PleasantValley

JerseyValley

Wah WahValley

SnakeValley

NorthSpringValley

TippettValley

Thou

sand

Spr

ings

Valle

y-To

ano a

nd

Rock

Spr

ing A

reas

Thou

sand

Spr

ings

Valle

y-Ro

cky

Butte

Are

a

GrouseCreekValley

East ParkValley

West ParkValley

PilotValleyPilot

CreekValley

ThousandSpringsValley-

Montelloand

CrittendenArea

Great SaltLake Desert

GoshuteValley

SinkValley

GreatSalt Lake

TooeleValleySkull

Valley

AntelopeValley

CacheValley

CurlewValley

Hanseland

NorthernRozel Flat

PocatelloandBlueCreek

ValleysLowerBearRiverBasin

EastShoreArea

Salt LakeValley

Utah Valley

CedarValley

RushValley

DugwayValley

DeepCreekValley

NorthernJuab

Valley

LeamingtonCanyon Area

Sevier Desert

FishSprings

Flat

TuleValley

PavantValley

CaveValley

WhiteRiverValley

NorthRailroadValley

SouthLittle

SmokyValley

North LittleSmokyValley

LittleFishLake

Valley

MonitorValley

Big SmokyValley-

Northernpart

UpperReeseRiverValley

AntelopeValley

KobehValley

GrassValley

CaricoLake

Valley

AntelopeValley

SteptoeValley

SouthButteValleyLong

Valley

JakesValley

NewarkValley

DiamondValley

PineValley

MiddleReeseRiverValley

HumboldtRiverBasin-

WinnemuccaSegment

BuffaloValley

HumboldtRiver

Basin-RedHouse

SegmentRockCreekValley

MaggieCreekBasin Susie

CreekArea

Humbo

ldt R

iver

Basin-E

lko an

d

Mary

s Cree

k Seg

ment

Dixie Creekand TenmileCreek Basin

SouthForkArea

LowerReeseRiverValley Crescent

Valley

Humboldt RiverBasin-BoulderFlat Segment

HuntingtonValley

RubyValley

NorthButteValley

CloverValley

Independence

Valley

HardscrabbleArea

LittleHumboldt

Valley

ParadiseValley

WillowCreekValley

North ForkHumboldt

River Basinand

LamoilleValley

UpperHumboldt

River Basin

Thousand SpringsValley-Herrell

Siding and BrushCreek Area

DetritalValley

LakeMohaveBasin

TruxtonWash

HualapaiBasin

LakeMeadBasin

Garnetand

HiddenValleys

CaliforniaWash

LowerMoapaValley

MuddyRiver

SpringsArea

LowerMeadowValleyWash

KaneSpringsValley

DelamarValley

CloverValley

PanacaValley

EscalanteDesertEagle-

Rose-DryValley

PattersonValley

SouthSpringValley

PineValley

LakeValley

Dry LakeValley

PahrocValley

CedarCity

Valley

MilfordArea

BeaverValley

ParowanValley

Las VegasValley

SacramentoValley

MohaveValley

South PiuteValley

NorthPiuteValley

Big SandyRiverBasin

BigChinoBasin

VerdeValley

San JoaquinValley

SouthTikapooValley

CoyoteSpringValley

PahranagatValleyNorth

TikapooValley

EmigrantValley

YuccaFlat

OasisValley

GoldFlat

CactusFlat

KawichValley

CoalValley

GardenValley

PenoyerValley

SouthRailroadValley

Hot CreekValley

StoneCabinValley

SalineValley

EurekaValley

DeepSpringsValley

NorthOwensValley

SarcobatusFlat

LidaValley

LongValley

Fish LakeValley

ClaytonValley Stonewall

Flat

RalstonValleyBig Smoky

Valley-Tonapah Flat

ColumbusSalt Marsh

Valley

AlkaliSpringValley

Adobe LakeValley

MonoValley

HuntoonValley

TeelsMarshValley

RhodesSalt Marsh

Valley

MonteCristoValley

GarfieldFlatBridgeport

Valley

AntelopeValley

FennerValley

KelsoValley

Soda LakeValley

Lower MohaveRiver Valley

Harper Valley CoyoteLake Valley

CroniseValleySuperiorValley

GoldstoneValley

Red PassValley

RiggsValley

BicycleValley

SouthIvanpahValley

ShadowValley

NorthIvanpahValley

MesquiteValley

ValjeanValley

CaliforniaValley

ChicagoValley

FreemontValley Cuddeback

Valley

SearlesValley

East PilotKnobandBrown

MountainValleys

LeachValley

Lost Lakeand Owl Lake

Valleys

IndianWellsValley

RoseValley

PanamintValley

DeathValley

DarwinPlateauBasins

SouthOwensValley

Race Trackand Hidden

Valleys

AmargosaDesert

LowerAmargosa

Valley

PahrumpValley

IndianSpringsValley

FrenchmanFlat

South ThreeLakesValley

NorthThreeLakes Valley

FortymileWash

CraterFlat

MercuryValley

RockValley

LanfairValley

EldoradoValley

HiddenValley

JeanLake

Valley

Tomales-DrakesBasin Novato

Valley Concord-Pittsburg

AreaSan RamonValleyEast Bay

Plain

San FranciscoBay Peninsula

Basins

SanMateoCoastalBasins

SantaClaraValley

Livermoreand Sunol

Valleys

UpperCoyoteCreekBasin

MontereyBasin

San Benito-Upper PajaroRiver Basin

CentralCalifornia

CoastalBasin

MiddleSalinas River

Valley

LockwoodValley

CholameValley

UpperSalinas

River Valley

CarrizoPlain

CuyamaValleySanta

Maria RiverValleySan Antonio

Creek Valley

CoachellaValley

BorregoValley

SaltonSea

Cottonwood,Campo, and

Potrero Valley

Vallecito,Carrizo,

and CoyoteWells Valleys

OrocopiaValley

PintoBasin

OgilbyValley

ImperialValley

ChuckwallaValley

ArroyoSeco Basin

PaloVerdeValley

YumaWash

La PosaPlain

Ward andRice

Valleys

JohnsonValley

TwentyninePalms Area

BristolValley

DaleValley

CadizValley

Parker andVidal

Valleys

RenegrasPlain

ChemehueviValley Lake

HavasuBasin

Lower BillWilliams

River Basin

BroadwellValleyLavic

Valley

ButlerValley

King andSan

CristobalValleys

Upper MohaveRiver Valley

Santa AnaInlandBasin

SanJacintoBasin

TemeculaValleySanta

MargaritaValley

San Luis Rey-Escondido

Coastal Basin

YumaBasin

LucerneValley

MohaveRiverValley

LechuquillaDesert Mohawk

Valley

SantaYnez River

Valley

Santa BarbaraCoastal Basins VenturaRiverValley

SantaClara River

Valley

Calleguas-OxnardBasin

MalibuCoastalBasins

CoastalPlain of

Los Angeles

San GabrielValley

Santa AnaCoastalBasin

Aliso-San Onofre

Coastal Basins

San DiegoCoastalBasins

SanFernando Valley

Palomas andSentinalPlains

McMullenValley

HarquahalaBasin

BullardWash

BurroCreekBasin Little

ChinoBasin

Agua FriaRiverBasin

KirklandCreekBasin

Lower VerdeRiver Basin

UpperHassayampaRiver Basin

LakePleasant

ParadiseValleyMiddle

HassayampaRiver Basin

Salt RiverValley-

Phoenix Area

Salt RiverValley-Chandler Area

GrowlerValley

GilaBendBasin

WatermanWash

Valley ofthe Ajo

VekolValley

StanfieldArea

EloyArea

DonnellyWash

DrippingSpringsWash

Lower SanPedro River

Basin

SantaRosa

ValleyAguirreValley

AvraValley

WillcoxBasin

San SimonValley

AravaipaValley

SaffordValley

QuijotoaValley

Baboquivariand Tecolote

ValleysAltarValley

Upper SantaCruz River

BasinCienegaCreekBasin Upper

San PedroRiver Basin

DouglasBasin

DuncanBasin

LordsburgBasinAnimas

Basin

MimbresRiverBasin

PlayasBasin

MesillaBasin

PalomasBasin

Jornada delMuerto Basin-Southern Part

TularosaBasin

EngleBasin

Montecello-Cuchillo

Basin

SanAgustinBasin

SanMarcialBasin

Jornada delMuerto Basin-Northern Part

SocorroBasin

La JenciaBasin

Albuquerque-BelenBasin

EspanolaBasin

San LuisValley

ARIZONA NEW MEXICO

UTAH COLORADO

MEXICO

OREGON

CALIFORNIA

IDAHO

WYOMINGNEVADA

35°

40°

40°

124°

124°

117°

110°

RenoReno

SacramentoSacramento

SanFrancisco

SanFrancisco

StocktonStockton

ModestoModesto

San JoseSan Jose

FresnoFresno

BakersfieldBakersfield

Las VegasLas Vegas

Los AngelesLos Angeles

San DiegoSan DiegoYumaYuma

PhoenixPhoenix

TucsonTucson

El PasoEl Paso

FlagstaffFlagstaff

Santa FeSanta Fe

AlbuquerqueAlbuquerque

Salt Lake CitySalt Lake City

U.S. Geological Survey digital data, 1:2,000,000, 2,500,000, and 5,000,000 scale, 2003, 2005, and 2006National Elevation Data 1:24,000, 1999Albers Equal Area Conic Projection, central meridian -113, NAD 83

Pacific Ocean

LasCruces

LasCruces

Observed and predicted arsenic concentrations in basin-fill aquifers of the Southwest Principal Aquifers study areaBy

Kimberly R. Beisner, David W. Anning, Angela P. Paul, Tim S. McKinney, Jena M. Huntington, Laura M. Bexfield, and Susan A. Thiros2012

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government.

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 80225, 1–888–ASK–USGS

Digital files available at http://pubs.usgs.gov/sim/3234/

Suggested citation: Beisner, K.R., Anning, D.W., Paul, A.P., McKinney, T.S., Huntington, J.M., Bexfield, L.M., and Thiros, S.A., 2012, Maps of estimated nitrate and arsenic concentrations in basin-fill aquifers of the southwestern United States: U.S. Geological Survey Scientific Investigations Map 3234, pamphlet 8 p., 2 sheets.Printed on recycled paper

0 50 100 150 200 MILES

0 50 100 150 200 KILOMETERS

NATIONAL GEODETIC VERTICAL DATUM OF 1929

ElkoElko

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

National Water-Quality Assessment Program Scientific Investigations Map 3234Sheet 2 of 2

Southwest Principal Aquifer (SWPA) study-area boundary

117°

35°

110°

AlamosaAlamosa

Concentration data is from Anning and others, 2012, for an aquifer penetration depth of 200 feet. Systematic changes in predicted concentrations with aquifer penetration depth were not found in most areas