U.S. Department of the Interior

U.S. Geological Survey

Data Series 803

Prepared in cooperation with the California State Water Resources Control Board

Groundwater-Quality Data in the Klamath Mountains

Study Unit, 2010: Results from the California GAMA Program

A product of the California Groundwater Ambient Monitoring and Assessment (GAMA) Program

5

5

101

97

199

89

96

96

299

299

Pacific Ocean

SCOTT RIVER VALLEY

HOOPA

VALLEY

HAYFORK

VALLEY

SEIAD

HAPPY CAMP VALLEY

TOWN AREA

HYAMPOM

VALLEY

WILSON

POINT

AREA

Klamath River

Trinity River

Pit River

Sacramento River

Smith River

Salmon River

Trinity River

Scott River

Etna

Yreka

Redding

Gasquet

Dunsmuir

Weaverville

Willow Creek

SISKIYOU CO

OREGON

SHASTA CO

TRINITY CO

HUMBOLDT CO

TEHAMA CO

DEL

NORTE

CO

Mt. Shasta

Mt. Shasta

Siskiyou Mts

Marble Mts

Salmon Mts

Scott Mts

Trinity Alps

Mt. Eddy
Cover photographs:

Top photo: Well house near Lewiston, California. (Photograph by Tracy Davis, U.S. Geological Survey)

Bottom photo: Trinity River near Junction City, California. (Photograph by Dara Goldrath, U.S. Geological Survey)
Groundwater-Quality Data in the Klamath 

Mountains Study Unit, 2010: Results from the 

California GAMA Program

By Timothy M. Mathany and Kenneth Belitz

A product of the California Groundwater Ambient Monitoring and Assessment (GAMA) Program

Prepared in cooperation with the California State Water Resources Control Board 

Data Series 803

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: 2014

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Suggested citation:

Mathany, T.M., and Belitz, Kenneth, 2014, Groundwater-quality data in the Klamath Mountains study unit, 2010—

Results from the California GAMA Program: U.S. Geological Survey Data Series 803, 82 p., http://dx.doi.org/10.3133/

ds803.

ISSN 2327-638X (online)
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................4

Hydrogeologic Setting ..................................................................................................................................4

Methods ........................................................................................................................................................12

Study Design........................................................................................................................................12

Sample Collection and Analysis.......................................................................................................13

Data Reporting.....................................................................................................................................13

Quality-Assurance Methods.............................................................................................................13

Quality-Control Results ......................................................................................................................13

Comparison Benchmarks ..................................................................................................................14

Water-Quality Results ................................................................................................................................15

Water-Quality Indicators (Field and Laboratory)...........................................................................15

Organic Constituents..........................................................................................................................15

Inorganic Constituents.......................................................................................................................16

Isotopic Tracers and Dissolved Noble Gases ................................................................................16

Uranium and Other Radioactive Constituents................................................................................17

Microbial Indicators...........................................................................................................................17

Future Work ..................................................................................................................................................17

Summary .......................................................................................................................................................17

Acknowledgments.......................................................................................................................................18

References Cited..........................................................................................................................................18

Tables ...........................................................................................................................................................25

Appendix .......................................................................................................................................................63
iv

Figures

1. Map showing the hydrogeologic provinces of California and the location of the 

Klamath Mountains (KLAM) GAMA study unit ........................................................................3

2. Map showing the boundaries of the Klamath Mountains (KLAM) study unit, 

topographic features, major cities, major roads, hydrologic features, the location of 

California Department of Public Health (CDPH) sites, and the distribution of the grid 

cells.................................................................................................................................................5

3. Maps (A–E) showing the Klamath Mountains (KLAM) GAMA study unit, the 

distribution of the grid cells, sampled sites, the location of California Department 

of Public Health (CDPH) sites, major cities, and major roads ...............................................6

4. Map showing the geology of the Klamath Mountains (KLAM) GAMA study unit ...........11

Tables

1. Identification, sampling, and construction information for sites sampled for the 

Klamath Mountains (KLAM) GAMA study unit, California, October to 

December 2010............................................................................................................................25

 2. Classes of chemical constituents and field water-quality indicators collected for 

the Klamath Mountains (KLAM) GAMA study unit, California, October to 

December 2010............................................................................................................................27

 3A. Volatile organic compounds, primary uses or sources, comparison benchmarks, 

and reporting information for the U.S. Geological Survey National Water Quality 

Laboratory Schedule 2020.........................................................................................................28

 3B. Pesticides and pesticide degradates, primary uses or sources, comparison 

benchmarks, and reporting information for the USGS National Water Quality 

Laboratory Schedule 2003.........................................................................................................31

 3C. Perchlorate, primary uses or source, comparison benchmark, and reporting 

information for Weck Laboratories, Inc. (Weck), City of Industry, California, 

analyses .......................................................................................................................................33

 3D. Trace elements, comparison benchmarks, and reporting information for the 

USGS National Water Quality Laboratory Schedule 1948 ...................................................34

 3E. Nutrients, comparative benchmarks, and reporting information for the USGS 

NWQL Schedule 2755.................................................................................................................35
v

 3F. Major and minor ions, silica, total dissolved solids, and alkalinity, comparative 

benchmarks, and reporting information for the USGS NWQL Schedule 1948 .................36

 3G. Arsenic and iron species, comparison benchmarks, and reporting information 

for the USGS National Research Laboratory Trace Metal Laboratory, Boulder, 

Colorado, analyses .....................................................................................................................36

 3H. Dissolved noble gases, isotopic tracers, and uranium and other radioactive 

constituents, comparison benchmarks and reporting information for laboratory 

analyses .......................................................................................................................................37

 3I. Microbial indicators, comparison benchmarks, and reporting information for the 

IDEXX Colilert® field test kit analyses......................................................................................38

 4. Water-quality indicators in samples collected for the Klamath Mountains (KLAM) 

GAMA study unit, California, October to December 2010....................................................39

 5. Volatile organic compounds detected in samples collected for the Klamath 

Mountains (KLAM) GAMA study unit, California, October to December 2010 .................42

 6. Pesticides and pesticide degradates detected in samples collected for the 

Klamath Mountains (KLAM) GAMA study unit, California, October to 

December 2010............................................................................................................................44

 7. Trace elements detected in samples collected for the Klamath Mountains (KLAM) 

GAMA study, California, October to December 2010............................................................45

 8. Nutrients detected in samples collected for the Klamath Mountains (KLAM) 

GAMA study unit, California, October to December 2010....................................................50

 9. Major and minor ions, silica, and total dissolved solids detected in samples 

collected for the Klamath Mountains (KLAM) GAMA study unit, California, 

October to December 2010........................................................................................................52

 10. Arsenic and iron species detected in samples collected for the Klamath 

Mountains (KLAM) GAMA study unit, California, October to December 2010 .................55

 11. Isotopic tracers detected in samples collected for the Klamath Mountains 

(KLAM) GAMA study unit, California, October to December 2010 .....................................56

 12. Results for the Lawrence Livermore National Laboratory (LLNL) analyses of 

tritium, dissolved noble gases, and helium isotope ratios in samples collected 

for the Klamath Mountains (KLAM) GAMA study unit, California, October to 

December 2010............................................................................................................................57

 13. Uranium and other radioactive constituents detected in samples collected for the 

Klamath Mountains (KLAM) GAMA study unit, California, October to 

December 2010............................................................................................................................59

 14. Microbial indicators detected in samples collected for the Klamath Mountains 

(KLAM) GAMA study unit, California, October to December 2010 .....................................62

Tables—Continued
vi

Conversion Factors and Datums

Inch/Pound to International System of Units (SI)

Multiply By To obtain

inch (in.) 2.54 centimeter (cm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

square mile (mi2

) 2.590 square kilometer (km2) 

quart (qt) 0.9464 liter (L)

pound, avoirdupois (lb) 0.4536 kilogram (kg)

SI to Inch/Pound

Multiply By To obtain

centimeter (cm) 0.3937 inch (in.)

kilometer (km) 0.6214 mile (mi)

square kilometer (km2

) 0.3861 square mile (mi2)

liter (L) 1.0567 quart (qt)

gram (g) 0.03527 ounce, avoirdupois (oz)

kilogram (kg) 2.205 pound, avoirdupois (lb)

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

°F=(1.8×°C)+32.

Specific conductance is given in microsiemens per centimeter at 25 degrees Celsius (μS/cm at 

25 °C).

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

or micrograms per liter (μg/L). 

Milligrams per liter is equivalent to parts per million (ppm), and micrograms per liter is 

equivalent to parts per billion (ppb). 

Concentrations of radioactive constituents in water (except uranium) are given in picocuries per 

liter (pCi/L).

Datums

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).

Land-surface altitude, as used in this report, refers to distance above the vertical datum and is 

reported as feet above mean sea level (ft above msl).
vii

Selected Terms and Symbols

α significance level

x activities of a radiochemical constituent in a groundwater sample

y activities of a radiochemical constituent in a replicate sample

cm3 STP/g cubic centimeters of gas at standard temperature and pressure (0 degrees 

Celsius and 1 atmosphere of pressure) per gram of water

δiE delta notation, the ratio of a heavier isotope of an element (iE) to the more 

common lighter isotope of that element, relative to a standard reference 

material, expressed as per mil

= equal to

> greater than 

≥ greater than or equal to

< less than

≤ less than or equal to

× multiplied by 

M presence verified but not quantified

N Normal (1-gram-equivalent per liter of solution)

— not detected

p p-value (probability) 

pH measure of the acidity of water

pK1,2 acid dissociation constants of carbonic acid

pKw acid dissociation constant of water

R ratio

σ sigma (standard deviation)

± plus or minus

* concentration greater than benchmark level

** concentration greater than upper benchmark level

Abbreviations and Acronyms

AL action level 

AL-US action level (USEPA)

APE Alternate Place Entry program designed for USGS sampling

CAS Chemical Abstract Service

CASRN Chemical Abstract Service (American Chemical Society) Registry Number®

CSU combined standard uncertainty
viii

E estimated or having a higher degree of uncertainty

GAMA Groundwater Ambient Monitoring and Assessment Program

GPS Global Positioning System

HAL lifetime health advisory level

HAL-US lifetime health advisory level (USEPA)

HPLC high-performance liquid chromatography

IBSP Inorganic Blind Sample Program (USGS)

KLAM Klamath Mountains study unit

KLAM-U Klamath Mountains study unit understanding (site)

LRL laboratory reporting level

LSD land-surface datum

LT-MDL long-term method detection level

MCL maximum contaminant level

MCL-CA maximum contaminant level (CDPH)

MCL-US maximum contaminant level (USEPA)

MDL method detection limit

MRL minimum reporting level

MU method uncertainty

na not available

NAD normalized absolute difference

nc not collected

NELAP National Environmental Laboratory Accreditation Program

NFM National Field Manual (USGS)

NFQA National Field Quality Assurance Program (USGS)

NL notification level

NL-CA notification level (CDPH)

np no preference

nv no measured value or no value in category

NWIS National Water Information System (USGS)

PBP Priority Basin Project

PCFF Personal Computer Field Form program designed for USGS sampling

QA quality assurance

QC quality control

RL reporting level

Abbreviations and Acronyms—Continued
ix

RPD relative percent difference

RSD relative standard deviation

RSD5-US risk-specific dose at a risk factor of 10–5 (USEPA)

SD standard deviation

SMCL secondary maximum contaminant level

SMCL-CA secondary maximum contaminant level (CDPH)

SMCL-US secondary maximum contaminant level (USEPA)

SRL study reporting level (concentration cutoff for applying the ≤ symbol in reporting 

results)

ssLC sample-specific critical level

TT-US treatment technique (USEPA)

UV ultraviolet

VPDB Vienna Pee Dee Belemnite (the international reference standard for carbon 

isotopes)

VSMOW Vienna Standard Mean Ocean Water (an isotopic water standard defined in 1968 

by the International Atomic Energy Agency)

Organizations

BQS Branch of Quality Systems (USGS)

CDPH California Department of Public Health

CDPR California Department of Pesticide Regulation

CDWR California Department of Water Resources

LLNL Lawrence Livermore National Laboratory, Livermore, California

NAWQA National Water-Quality Assessment Program (USGS)

NRP National Research Program (USGS)

NWQL National Water Quality Laboratory (USGS)

SITL Stable Isotope and Tritium Laboratory, Menlo Park, California (USGS)

SWRCB California State Water Resources Control Board

TML Trace Metal Laboratory, Boulder, Colorado (USGS)

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

Weck Weck Laboratories, Inc., City of Industry, California

Abbreviations and Acronyms—Continued
x

Selected Chemical Names

CaCO3 calcium carbonate

CO3

2– carbonate ion

H2O water

HCl hydrochloric acid

HCO3

– bicarbonate ion

MEK methyl ethyl ketone (2-butanone)

MTBE methyl tert-butyl ether

PCE perchloroethene (tetrachloroethene)

SiO2 silicon dioxide

TCE trichloroethene

TDS total dissolved solids

THM trihalomethane

VOC volatile organic compound
Groundwater-Quality Data in the Klamath Mountains 

Study Unit, 2010: Results from the California 

GAMA Program

By Timothy M. Mathany and Kenneth Belitz

Abstract 

Groundwater quality in the 8,806-square-mile 

Klamath Mountains (KLAM) study unit was investigated 

by the U.S. Geological Survey (USGS) from October 

to December 2010, as part of the California State Water 

Resources Control Board (SWRCB) Groundwater Ambient 

Monitoring and Assessment (GAMA) Program’s Priority 

Basin Project (PBP). The GAMA-PBP was developed in 

response to the California Groundwater Quality Monitoring 

Act of 2001 and is being conducted in collaboration with 

the SWRCB and Lawrence Livermore National Laboratory 

(LLNL). The KLAM study unit was the thirty-third study unit 

to be sampled as part of the GAMA-PBP.

The GAMA Klamath Mountains study was designed 

to provide a spatially unbiased assessment of untreatedgroundwater quality in the primary aquifer system and to 

facilitate statistically consistent comparisons of untreatedgroundwater quality throughout California. The primary aquifer 

system is defined by the perforation intervals of wells listed in 

the California Department of Public Health (CDPH) database 

for the KLAM study unit. Groundwater quality in the primary 

aquifer system may differ from the quality in the shallower or 

deeper water-bearing zones; shallower groundwater may be 

more vulnerable to surficial contamination.

In the KLAM study unit, groundwater samples were 

collected from sites in Del Norte, Siskiyou, Humboldt, Trinity, 

Tehama, and Shasta Counties, California. Of the 39 sites 

sampled, 38 were selected by using a spatially distributed, 

randomized grid-based method to provide statistical 

representation of the primary aquifer system in the study 

unit (grid sites), and the remaining site was non-randomized 

(understanding site).

The groundwater samples were analyzed for basic field 

parameters, organic constituents (volatile organic compounds 

[VOCs] and pesticides and pesticide degradates), inorganic 

constituents (trace elements, nutrients, major and minor ions, 

total dissolved solids [TDS]), radon-222, gross alpha and gross 

beta radioactivity, and microbial indicators (total coliform and 

Escherichia coli [E. coli]). Isotopic tracers (stable isotopes 

of hydrogen and oxygen in water, isotopic ratios of dissolved 

strontium in water, and stable isotopes of carbon in dissolved 

inorganic carbon), dissolved noble gases, and age-dating 

tracers (tritium and carbon-14) were measured to help identify 

sources and ages of sampled groundwater.

Quality-control samples (field blanks, replicate sample 

pairs, and matrix spikes) were collected at 13 percent of the 

sites in the KLAM study unit, and the results were used to 

evaluate the quality of the data from the groundwater samples. 

Field blank samples rarely contained detectable concentrations 

of any constituent, indicating that contamination from sample 

collection or analysis was not a significant source of bias in 

the data for the groundwater samples. More than 99 percent 

of the replicate pair samples were within acceptable limits 

of variability. Matrix-spike sample recoveries were within 

the acceptable range (70 to 130 percent) for approximately 

91 percent of the compounds.

This study did not evaluate the quality of water delivered 

to consumers. After withdrawal, groundwater typically is 

treated, disinfected, and (or) blended with other waters to 

maintain water quality. Regulatory benchmarks apply to 

water that is delivered to the consumer, not to untreated 

groundwater. However, to provide some context for the 

results, concentrations of constituents measured in the 

untreated groundwater were compared with regulatory and 

non-regulatory health-based benchmarks established by the 

U.S. Environmental Protection Agency (USEPA) and CDPH, 

and to non-health-based benchmarks established for aesthetic 

concerns by the CDPH. Comparisons between data collected 

for this study and benchmarks for drinking water are for 

illustrative purposes only and are not indicative of compliance 

or non-compliance with those benchmarks.

All concentrations of organic constituents from grid 

sites sampled in the KLAM study unit were less than healthbased benchmarks. In total, VOCs were detected in 16 of the 

38 grid sites sampled (approximately 42 percent), pesticides 

and pesticide degradates were detected in 8 grid sites (about 

21 percent), and microbial indicators were detected in 14 grid 

sites (approximately 37 percent).

Inorganic constituents (trace elements, major and minor 

ions, nutrients, and uranium and other radioactive constituents) 

and microbial indicators were sampled for at 38 grid sites, and 
2 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

all concentrations were less than health-based benchmarks, 

with the exception of one detection of boron greater than 

the CDPH notification level of 1,000 micrograms per liter 

(μg/L). Generally, concentrations of inorganic constituents 

with non-health-based benchmarks (iron, manganese, chloride, 

and TDS) were less than the CDPH secondary maximum 

contaminant level (SMCL-CA). Exceptions include three 

detections of iron greater than the SMCL-CA of 300 μg/L, 

four detections of manganese greater than the SMCL-CA 

of 50 μg/L, one detection of chloride greater than the 

recommended SMCL-CA of 250 μg/L, and one detection of 

TDS greater than the recommended SMCL-CA of 500 μg/L.

Introduction 

About one-half of the water used for public and domestic 

drinking-water supply in California is groundwater (Kenny and 

others, 2009). To assess the quality of ambient groundwater in 

aquifers used for public drinking-water supply and to establish 

a baseline groundwater-quality monitoring program, the 

California State Water Resources Control Board (SWRCB), 

in cooperation with the U.S. Geological Survey (USGS) and 

Lawrence Livermore National Laboratory (LLNL), implemented 

the Groundwater Ambient Monitoring and Assessment (GAMA) 

Program in 2000 (California State Water Resources Control 

Board, 2011). The main goals of the GAMA Program are to 

improve groundwater monitoring and to increase the availability 

of groundwater-quality data to the public.

The GAMA Program currently consists of four projects: 

(1) the GAMA Priority Basin Project (PBP) conducted 

by the USGS (U.S. Geological Survey, 2011a); (2) the 

GAMA Domestic Well Project conducted by the SWRCB; 

(3) the GAMA Special Studies Project conducted by LLNL; 

and (4) GeoTracker GAMA, conducted by the SWRCB. 

The GAMA-PBP was initiated by the Groundwater Quality 

Monitoring Act of 2001 (State of California, 2001a, b; 

Sections 10780–10782.3 of the California Water Code, 

Assembly Bill 599). The USGS, in collaboration with the 

SWRCB, developed a monitoring plan to assess groundwater 

basins through direct and other statistically reliable sample 

approaches (Belitz and others, 2003; California State Water 

Resources Control Board, 2003). Additional partners in the 

GAMA-PBP include LLNL, the California Department of 

Public Health (CDPH), California Department of Water 

Resources (CDWR), California Department of Pesticide 

Regulation (CDPR), local water agencies, and well owners 

(Kulongoski and Belitz, 2004). The GAMA-PBP examines 

the part of the aquifer system used for public drinking-water 

supply, which typically is deeper than the part of the aquifer 

system used for domestic drinking-water supply. The GAMA 

Domestic Well Project generally focuses on the shallower 

aquifer systems, which may be particularly at risk as a result 

of surficial contamination. The GAMA Special Studies Project 

focuses on using research methods to help explain the source, 

fate, transport, and occurrence of chemicals that can affect 

groundwater quality. GeoTracker GAMA is an online interface 

serving all published and quality-assurance/quality-control 

(QA/QC) approved analytical data from the GAMA Program 

(California State Water Resources Control Board, 2009). 

GeoTracker GAMA also stores groundwater-quality data and 

related reports collected by other State agencies, such as the 

CDPH, CDWR, and CDPR, and data collected by the SWRCB 

and Regional Boards from groundwater monitoring wells at 

contaminated or remediated sites.

The GAMA-PBP is unique in California because it 

includes many chemical analyses that are not otherwise 

available in the statewide water-quality monitoring datasets. 

Groundwater samples collected for the GAMA-PBP are 

analyzed for approximately 300 chemical constituents by 

using methods with lower detection limits than required by the 

CDPH for regulatory monitoring of water from drinking-water 

wells. These analyses will be especially useful for providing 

an early indication of changes in groundwater quality. In 

addition, the GAMA-PBP analyzes samples for a suite of 

constituents more extensive than required by the CDPH and 

for a suite of chemical and isotopic tracers that can be used 

to further the understanding of hydrologic and geochemical 

processes. This understanding of groundwater composition is 

useful for identifying the natural and human factors affecting 

water quality. Understanding the occurrence and distribution 

of chemical constituents of significance to water quality is 

important for the long-term management and protection of 

groundwater resources.

In order to delineate areas for evaluation as part of the 

GAMA-PBP, the range of hydrologic, geologic, and climatic 

conditions in California needed to be considered. Belitz and 

others (2003) partitioned the State into 10 hydrogeologic 

provinces, each with distinctive hydrologic, geologic, and 

climatic characteristics: Cascades and Modoc Plateau, 

Klamath Mountains, Northern Coast Ranges, Central Valley, 

Sierra Nevada, Basin and Range, Southern Coast Ranges, 

Transverse Ranges and selected Peninsular Ranges, Desert, 

and San Diego Drainages (fig. 1). These 10 hydrogeologic 

provinces include 472 groundwater basins designated by 

the CDWR (California Department of Water Resources, 

2003). Groundwater basins generally consist of relatively 

permeable, unconsolidated deposits of alluvial origin. 

Eighty percent of California’s approximately 16,000 active 

and standby drinking-water wells (and springs) listed in the 

statewide database maintained by the CDPH (hereinafter 

referred to as CDPH sites) are located in groundwater basins. 

Groundwater basins were prioritized for sampling on the basis 

of the number of CDPH wells in the basin, with secondary 

consideration given to municipal groundwater use, agricultural 

pumping, the number of formerly leaking underground 

fuel tanks, and the number of square-mile sections with 

registered pesticide applications (Belitz and others, 2003). 

Of the 472 basins designated by the CDWR, 116 contain 

approximately 95 percent of the CDPH wells located in basins. 

These 116 basins were defined as “priority basins,” and the 
Introduction 3

Basin and Range

Central

Valley

Klamath

Mountains

Desert

Cascades and

Modoc Plateau

Transverse Ranges and

selected Peninsular Ranges

Southern Coast

Ranges

Sierra

Nevada

Northern

Coast

Ranges

San Diego

Drainages

 

Klamath

Mountains

Study Unit

(figure 2)

Bakersfield

San

Francisco

Sacramento

OREGON

NEVADA

MEXICO

ARIZONA

Redding

Los Angeles

San Diego

PA C I F I C O C E A N

0 200 MILES

0 200 KILOMETERS

100

100

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006, 

Albers Equal Area Conic Projection

Provinces from Belitz and others, 2003

sac14-0516_Figure 01

Figure 1. Hydrogeologic provinces of California and the location of the Klamath Mountains (KLAM) Groundwater Ambient Monitoring 

and Assessment (GAMA) study unit.
4 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

remaining 356 basins were defined as “low-use basins.” All of 

the priority basins, selected low-use basins, and selected areas 

outside of groundwater basins were grouped into 35 GAMA 

Priority Basin Project study units that together represent 

approximately 95 percent of all CDPH wells. 

The entire Klamath Mountains hydrogeologic province 

was defined as the Klamath Mountains (KLAM) study unit 

(fig. 1). The KLAM study unit includes seven priority basins 

and areas outside of groundwater basins. Groundwater is a 

major source of public drinking-water supply for many of the 

communities located in the KLAM study unit (Water Education 

Foundation, 2006; Dunsmuir Chamber of Commerce, 2012); 

therefore, the KLAM study unit was considered high priority 

for sampling to provide adequate representation of the Klamath 

Mountains hydrogeologic province.

The data collected in each study unit are used for three 

types of water-quality assessments: (1) Status—assessment 

of the current quality of the groundwater resource; 

(2) Understanding—identification of the natural and human 

factors affecting groundwater quality; and (3) Trends—

detection of changes in groundwater quality over time 

(Kulongoski and Belitz, 2004). The assessments are intended 

to characterize the quality of groundwater in the primary 

aquifer system of the study units, not the treated drinking 

water delivered to consumers by water purveyors. The primary 

aquifer system is defined as parts of aquifers corresponding to 

the perforation intervals of wells listed in the CDPH databases 

for the study units. The CDPH database lists wells and springs 

used for public drinking-water supplies and includes wells 

and springs from systems classified as community (such as 

those in cities, towns, and mobile-home parks), non-transient, 

non-community (such as those in schools, workplaces, and 

restaurants), and transient, non-community (such as those 

in campground and parks). Collectively, the CDPH refers 

to these as “public-supply” wells and springs (hereinafter 

referred to as CDPH sites). Groundwater quality in the 

primary aquifer system may differ from the quality in the 

shallow or deep parts of the aquifer system. 

This USGS Data Series Report is one of a series of 

reports presenting the water-quality data collected by the 

USGS in the KLAM study unit for the GAMA-PBP. Data 

Series Reports for each of the GAMA-PBP study units 

are available from the U.S. Geological Survey (2011b) at 

http://ca.water.usgs.gov/projects/gama/includes/GAMA_

publications.html.

Purpose and Scope

The purposes of this report are to describe (1) the 

hydrogeologic setting of the KLAM study unit, the study 

design, and the study methods; (2) the analytical results for 

groundwater samples collected in the KLAM study unit, and 

(3) the results of QC analyses. Groundwater samples were 

collected and analyzed for water-quality indicators; organic 

and inorganic constituents; isotopic and age-dating tracers; 

microbial indicators; and dissolved gases. The chemical data 

presented in this report were compared to State and Federal 

drinking-water standards. The health-based and non-healthbased benchmarks considered are those established by the 

U.S. Environmental Protection Agency (USEPA) and (or) the 

CDPH. Discussion of the factors that influence the distribution 

and occurrence of the constituents detected in groundwater 

samples will be the subject of subsequent publications.

Hydrogeologic Setting 

The KLAM study unit is located in a large region of 

northern California between the Northern Coast Ranges and the 

Cascades and Modoc Plateau hydrogeologic provinces (Belitz 

and others, 2003; fig. 1) and covers an area of 8,806 square 

miles (mi2) in parts of Del Norte, Siskiyou, Humboldt, Trinity, 

Tehama, and Shasta Counties, California (fig. 2).

The study unit boundary extends from approximately 

10 miles (mi) northwest of the city of Redding to the 

California/Oregon border (135 mi to the north) and from 

about 10 mi inland of the Pacific Ocean to the border of the 

Cascades and Modoc Plateau hydrogeologic province (about 

125 mi to the east, fig. 1). The study unit is characterized 

by high peaks and continuous ridgelines separated by deep 

river gorges. These gorges separate the study unit into several 

distinct mountain ranges, including the Trinity Alps and the 

Siskiyou, Scott, Marble, and Salmon Mountains (fig. 2). 

Land-surface altitudes in the study area range from 

about 400 feet above mean sea level (ft above msl) near the 

town of Gasquet, to over 9,000 ft above msl on Mount Eddy, 

located just west of the city of Mt. Shasta (figs. 2, 3A, 3B). 

The study unit includes parts of three major watersheds. 

Most of the study unit is drained by the Klamath River and 

its major tributaries, the Trinity and Salmon Rivers and their 

headwaters. The northwestern corner of the study unit is in 

the Smith River drainage basin (fig. 3A), and the southeastern 

corner of the study unit is drained by the Sacramento River 

and its tributary, the Pit River (fig. 3E). Shasta Lake on the 

Sacramento River and Trinity (Clair Engle) Lake on the upper 

Trinity River are large human-made reservoirs that supply 

water for the Federal Central Valley Project (fig. 3D). Water 

is diverted from the Trinity River to the Sacramento River 

through a tunnel in the Trinity Alps and the human-made 

Whiskeytown Lake reservoir (fig. 3D).

The climate in the study unit is typical of mountainous 

areas in northern California, with hot summers and cold 

winters (U.S. Department of Commerce, National Climatic 

Data Center, 2012). Generally, precipitation in the study unit 
Hydrogeologic Setting 5

5

5 101

99

97

199

36

89

96

96

299

299

124° 123°30’ 123° 122°30’ 122°

42°

41°

30'

41°

40°

30'

0 10 20 5 Miles

0 10 205 Kilometers

EXPLANATION

Klamath Mountains

 study unit boundary

CDWR-defined

 groundwater basin

Grid cell City

River CDPH site

Pacific Ocean

sac14-0516_Figure 02

SCOTT RIVER VALLEY

HOOPA

VALLEY

HAYFORK

VALLEY

SEIAD

HAPPY CAMP VALLEY

TOWN AREA

HYAMPOM

VALLEY

WILSON

POINT

AREA

Klamath River

Trinity River

Pit River

Sacramento River

Smith River

Salmon River

Trinity River

Scott River

Etna

Yreka

Redding

Gasquet

Dunsmuir

Weaverville

Willow Creek

SISKIYOU CO

OREGON

SHASTA CO

TRINITY CO

HUMBOLDT CO

TEHAMA CO

DEL

NORTE

CO

Mt. Shasta

Mt. Shasta

Siskiyou Mts

Marble Mts

Salmon Mts

Scott Mts

Trinity Alps

Mt. Eddy

Figure 2. Boundaries of the Klamath Mountains (KLAM) study unit, topographic features, major cities, major roads, hydrologic 

features, the location of California Department of Public Health (CDPH) sites, and the distribution of the grid cells. [CDWR, California 

Department of Water Resources]
6 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

199

101

96

KLAM-11

KLAM-10

KLAM-08

KLAM-01

124° 123°30’

41°

30’

42°

0

0 5 10 Kilometers

5 10 Miles

EXPLANATION

Grid cell

City

River

USGS-grid site and identifier

KLAM-26

CDWR-defined CDPH site groundwater basin

Klamath Mountains

 study unit boundary

Pacific Ocean

Klamath River

Klamath River

Gasquet

Smith River

TRINITY CO

HUMBOLDT CO

DEL

NORTE

CO

Salmon River

HAPPY CAMP

TOWN AREA

OREGON

sac14-0516_Figure 03a

A

Figure 3A–E. Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, the distribution of 

the grid cells, sampled sites, the location of California Department of Public Health (CDPH) sites, major cities, and major roads. [CDWR, 

California Department of Water Resources]
Hydrogeologic Setting 7

Figure 3A–E.—Continued

5

96

KLAM-31

KLAM-24

KLAM-17

KLAM-07

KLAM-06

KLAM-05

KLAM-04

KLAM-03

KLAM-02

0

0 5 10 Kilometers

5 10 Miles

123° 122°30’

41°

30’

EXPLANATION

Grid cell

City

River

USGS-grid site and identifier

KLAM-24

CDPH site CDWR-defined

 groundwater basin

Klamath Mountains

 study unit boundary

sac14-0516_Figure 03b

B

Etna

Yreka

SISKIYOU CO

TRINITY CO Trinity River

Klamath River

SCOTT RIVER VALLEY

SEIAD

VALLEY

Mt. Eddy
8 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Figure 3A–E.—Continued

96

299 KLAM-U-01

KLAM-22

KLAM-15

KLAM-14

KLAM-09

123°30’ 123°

0 2 3 4 5 1 Miles

0 1 2 3 4 5 Kilometers

USGS-understanding site

 and identifier

KLAM-U-01

HYAMPOM

VALLEY

Trinity River

Willow Creek

41°

40°

45’

TRINITY CO

HUMBOLDT CO

sac14-0516_Figure 03c

C

EXPLANATION

Grid cell

City

River

USGS-grid site and identifier

KLAM-14

CDPH site

CDWR-defined

 groundwater basin

Klamath Mountains

 study unit boundary
Hydrogeologic Setting 9

Figure 3A–E.—Continued

5

299

KLAM-38

KLAM-37

KLAM-36

KLAM-35

KLAM-33

KLAM-26

KLAM-23

KLAM-21

KLAM-20

KLAM-19

KLAM-18

KLAM-16

KLAM-13

KLAM-12

0

0 5 10 Kilometers

5 10 Miles

123° 122°30’

41°

40°

30’

SISKIYOU CO

SHASTA CO

TRINITY CO

Weaverville

Redding

Trinity River

Trinity River

Trinity River

Sacramento River

Sacramento River

sac14-0516_Figure 03d

D

Shasta Lake

Trinity

(Clair Engle)

Lake

EXPLANATION

Grid cell

City

River

Lake

USGS-grid site and identifier

KLAM-26

CDWR-defined CDPH site groundwater basin

Klamath Mountains

 study unit boundary
10 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Figure 3A–E.—Continued

299

89

5

KLAM-34

KLAM-33

KLAM-32

KLAM-30

KLAM-29

KLAM-28

KLAM-27

KLAM-25

KLAM-16

0

0 5 10 Kilometers

5 10 Miles

122°30’ 122°

41°

41°

10’

40°

50’

Pit River

Sacramento River

Trinity River

Dunsmuir

sac14-0516_Figure 03e

E

Shasta Lake

EXPLANATION

Grid cell USGS-grid site and identifier

KLAM-34

CDWR-defined CDPH site groundwater basin

Klamath Mountains

 study unit boundary

City

River

Lake
Hydrogeologic Setting 11

5

5 101

99

97

199

36

89

96

96

299

KLAM-U-01 299

KLAM-12

KLAM-38

KLAM-37

KLAM-36

KLAM-35 KLAM-34

KLAM-33

KLAM-32

KLAM-31

KLAM-30

KLAM-29

KLAM-28

KLAM-27

KLAM-26

KLAM-25

KLAM-24

KLAM-23

KLAM-22

KLAM-21

KLAM-20

KLAM-13

KLAM-19

KLAM-18

KLAM-17

KLAM-16

KLAM-15

KLAM-14

KLAM-11

KLAM-10

KLAM-09

KLAM-08

KLAM-07

KLAM-06

KLAM-05

KLAM-04

KLAM-03

KLAM-02

KLAM-01

USGS-grid site and identifier

USGS-understanding site

 and identifier

KLAM-26

124° 123°30’ 123° 122°30’ 122°

42°

41°

30'

41°

40°

30'

0 10 20 5 Miles

0 10 205 Kilometers

EXPLANATION

Klamath Mountains

 study unit boundary

CDWR-defined

 groundwater basin

City

River

Lake

Fault

Pacific Ocean

KLAM-U-01

Sedimentary rocks Other rocks

Franciscan complex

Plio-Pleistocene sediment

Quaternary alluvium

Quaternary other sediment

Tertiary nonmarine sediment

Tertiary marine sediment

Granitic rocks

Metamorphic other

Metasediment

Ultramafic/mafic

sac14-0516_Figure 04

SCOTT RIVER VALLEY

HOOPA

VALLEY

HAYFORK

VALLEY

SEIAD

HAPPY CAMP VALLEY

TOWN AREA

HYAMPOM

VALLEY

WILSON

POINT

AREA

Klamath River

Trinity River

Pit River

Sacramento River

Smith River

Salmon River

Trinity River

Etna

Yreka

Redding

Gasquet

Dunsmuir

Weaverville

Willow Creek

SISKIYOU CO

OREGON

SHASTA CO

TRINITY CO

HUMBOLDT CO

TEHAMA CO

DEL

NORTE

CO

Geology from Saucedo and others, 2000.

Figure 4. Geology of the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study unit. [CDWR, 

California Department of Water Resources]
12 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

reflects a rain shadow effect from west to east due to the 

repeated mountain ranges, whereas snowfall increases from 

south to north with elevation. Average annual precipitation 

in the study unit ranges from about 69 inches (in.) on the 

western edge of the study unit along the Northern Coast 

Ranges to about 40 in. in the central and eastern parts of the 

study unit (U.S. Department of Commerce, National Climatic 

Data Center, 2012; Western Regional Climate Center, 2012). 

Annual snow accumulation averages approximately 9 in. 

in the southern part of the study unit, 14 in. in the central 

part, and 22 in. in the northern reaches of the study unit 

(U.S. Department of Commerce, National Climatic Data 

Center, 2012; Western Regional Climate Center, 2012).

Geologically, the study unit is composed predominantly 

of Mesozoic volcanic rocks and Paleozoic to Mesozoic marine 

sedimentary and ophiolitic rocks (fig. 4). Regional studies 

conducted by the USGS and others have divided the Klamath 

Mountains geological region into nine terranes separated 

from each other by major east-dipping fault zones (Irwin and 

Wooden, 1999; Snoke and Barnes, 2006). The terranes are 

bounded by regional thrust faults that are older in eastern 

parts of the study unit and younger to the west. Additionally, 

granitic plutons of Mesozoic age were emplaced into the 

terranes in several areas of the study unit (Snoke and Barnes, 

2006). Metamorphism occurred before and after accretion 

of these terranes along the edge of the North American plate 

during subduction of the Gorda plate (Wright, 1982). 

For the purposes of this report, the sampled sites were 

classified by the general rock type in which they are located 

by use of a simplified ArcGIS geology layer modified by the 

GAMA Program (Saucedo and others, 2000). Within the KLAM 

study unit boundary, there are four dominant classifications 

of rock types: granitic (dark pink), metamorphic other (dark 

green), metasediment (light green), and ultramafic/mafic (light 

pink) (fig. 4). In summary, 4 sampling sites were located in 

granitic rock, 9 sites in metamorphic other rock, 19 sites in 

metasediment rock, and 7 sites in ultramafic/mafic rock.

The primary aquifer system in most of the study unit 

is made up of localized areas of fractured bedrock generally 

considered to be confined to semi-confined (Mack, 1960). In 

addition to production wells that are bored into the bedrock, 

numerous springs and horizontal wells are a significant source 

of water for many communities and campgrounds located 

within the study unit (Dunsmuir Chamber of Commerce, 

2012; K. Stagg, U.S. Forest Service, Klamath National Forest, 

written commun., 2012). These springs and horizontal wells 

flow under artesian conditions for all or most of the year. 

The seven CDWR-defined groundwater basins (Scott River 

Valley, Hayfork Valley, Hoopa Valley, Happy Camp Town 

Area, Seiad Valley, Hyampom Valley, and Wilson Point Area) 

consist of alluvial fan, stream channel, and floodplain deposits 

of Quaternary age located within the study unit (California 

Department of Water Resources, 2004a–g: fig. 4). No sample 

sites were available during the period of study within these 

groundwater basins, and the connection between these alluvial 

deposits and the hard rock aquifer systems is unknown.

Groundwater recharge in the study unit consists 

of precipitation runoff, snowmelt, and streamflow that 

penetrate the bedrock through faults and fractures (California 

Department of Water Resources, 1984). Groundwater flow 

in the study unit is through numerous fracture systems 

related to local and regional faults. Unlike large groundwater 

basins which can develop regional-scale groundwater-flow 

patterns, the groundwater-flow patterns in steep mountainous 

terrains are controlled at much more localized scales that are 

dependent on local topography, faults and fracture systems, 

and the arrangement of discharge zones (Toth, 1963; Snoke 

and Barnes, 2006). 

Methods 

Methods used for the GAMA-PBP were selected to 

achieve the following objectives: (1) collect groundwater 

samples that are statistically representative of the primary 

aquifer system in each study unit; (2) collect samples in a 

consistent manner; (3) analyze samples by using proven and 

reliable laboratory methods; (4) assure the quality of the 

groundwater data; and (5) maintain data securely and with 

relevant documentation. The appendix contains detailed 

descriptions of the sample-collection protocols, analytical 

methods, and the QC data analysis.

Study Design

The wells and springs (hereinafter referred to as “sites”) 

selected for sampling in the KLAM study unit were selected 

to provide a statistically unbiased, spatially distributed 

assessment of the quality of groundwater used for public 

drinking-water supply. 

The area of the KLAM study unit where groundwater 

is used for public drinking-water supply was divided into 

grid cells, and the objective was to sample one site in each 

cell (hereinafter referred to as “grid sites”). The KLAM 

study unit has 204 CDPH sites; however, these sites are not 

evenly distributed. To minimize the number of cells having 

no potential sampling sites, only the parts of the study unit 

near CDPH sites were included in the gridded area. A 1.86-mi 

(3-km) radius circle was drawn around each CDPH site, and 

the collective area encompassed by the circles was divided 

into forty 23-mi2

 (60-km2) grid cells (Scott, 1990). A single 

grid cell may consist of non-contiguous pieces separated by 

non-gridded areas. 

The CDPH sites all were assigned random rankings, 

and the highest ranking CDPH site in each cell that met basic 

sampling criteria (for example, sampling point located prior 

to treatment or capability to pump for several hours) and for 

which permission to sample could be obtained was sampled as 

the grid site. If a grid cell contained no accessible CDPH sites, 

then door-to-door canvassing and USGS databases were used 

to identify domestic, irrigation, and other wells appropriate 
Methods 13

for sampling. The non-CDPH wells selected as grid sites had 

depths and screened intervals similar to those in CDPH wells 

in the area. Grid sites were sampled in in 38 of the 40 grid 

cells; the other 2 cells contained no accessible sites. The 

38 grid sites sampled were numbered in the order in which 

samples were collected with the prefix of “KLAM.” 

One additional off-grid site was sampled and hereinafter 

is referred to as the “understanding site” for consistency 

with the nomenclature used for non-grid sites in reports for 

other GAMA PBP study units. This site was not included 

in the statistical characterization of water quality in the 

KLAM study unit because inclusion of this site would have 

led to the overrepresentation of the previously sampled 

grid cells. This additional site was named with the prefix 

“KLAM-U” (“U” indicates “understanding”) (fig. 3C). The 

GAMA site identification number for each sample, along 

with the date sampled, site type, land-surface altitude, and 

available construction information, is shown in table 1. 

Groundwater samples were collected from 32 production wells 

(30 CDPH wells, 1 domestic well, and 1 commercial well) 

and 7 CDPH springs during the time period from October to 

December 2010. 

Site locations were verified by using a global positioning 

system (GPS), 1:24,000-scale USGS topographic maps, 

existing well information in USGS and CDPH databases, and 

information provided by well owners, drillers’ logs, and other 

sources of site information. Site and sample information were 

recorded in the field by hand on field sheets and electronically 

on field laptop computers using the Alternate Place Entry 

(APE) program designed by the USGS. All information 

was verified and entered into the USGS National Water 

Information System (NWIS) database. Site owner, site use, 

and site location are not published.

Sample Collection and Analysis

Samples were collected in accordance with the USGS 

National Field Manual (NFM) (U.S. Geological Survey, 

variously dated) and modified USGS National Water-Quality 

Assessment (NAWQA) Program (Koterba and others, 1995) 

sampling protocols. These sampling protocols were followed 

so that samples representative of groundwater in the aquifer 

were collected at each site and so that the samples were 

collected and handled in ways that minimized the potential 

for contamination. Use of the sampling protocols also allows 

comparison with data collected by GAMA-PBP throughout 

California and with other USGS projects in California and the 

Nation.

All 39 sites in the KLAM study unit were sampled for the 

same set of constituents (table 2). Groundwater samples were 

analyzed for 85 VOCs (table 3A); 63 pesticides and pesticide 

degradates (table 3B); perchlorate (table 3C); 24 trace 

elements (table 3D); 5 nutrients (table 3E); 9 major and 

minor ions, silica, total dissolved solids (TDS), and alkalinity 

(table 3F); arsenic and iron species (table 3G); 6 isotopic 

tracers, uranium and 9 other radioactive constituents, and 

5 dissolved noble gases (table 3H); and 2 microbial indicators 

(table 3I). The methods used for sample collection and 

analysis are described in the appendix section titled “Sample 

Collection and Analysis.”

Data Reporting

Many of the constituents presented in this report have 

different laboratory reporting conventions; additionally, some 

of the constituents were analyzed by different analytical 

laboratories or methods. The appendix section titled “Data 

Reporting” gives details for the laboratory reporting 

conventions for all constituents and the method preferences 

for those constituents that were analyzed by multiple methods 

or by multiple laboratories in the KLAM study unit.

Quality-Assurance Methods

The QA/QC procedures used for this study followed the 

protocols described in the NFM (U.S. Geological Survey, 

variously dated) and used by the NAWQA Program (Koterba 

and others, 1995). The QA plan followed by the National 

Water Quality Laboratory (NWQL), the primary laboratory 

used to analyze samples for this study, is described in Pirkey 

and Glodt (1998) and Maloney (2005). QC samples collected 

in the KLAM study unit were field blanks, replicate sample 

pairs, and matrix- and surrogate-spike samples. QC samples 

were collected to evaluate potential contamination, as well 

as bias and variability of the data that may have resulted 

from sample collection, processing, storage, transportation, 

and laboratory analysis. QA/QC procedures and results are 

described in the appendix section titled “Quality-Assurance 

and Quality-Control Methods and Results.”

Quality-Control Results

Results of QC analyses (field blank samples, replicate 

sample pairs, and matrix- and surrogate-spike samples) were 

used to evaluate the quality of the data for the groundwater 

samples. On the basis of detections in laboratory and field 

blank samples collected for this and for previous GAMAPBP study units, the reporting levels (RLs) for three VOCs 

and nine trace elements were raised in this report (Olsen 

and others, 2010; Fram and others, 2012). The GAMA 

Program refers to these raised reporting levels as “study 

reporting levels” (SRLs). Detections of the three VOCs 

reported by the laboratory with concentrations less than 

the SRL were considered non-detections in this study to 

reduce the likelihood of reporting results that could be 

false positives. Data for perchlorate are not presented in 

this report because the data failed to meet the GAMA-PBP 

QC standards. Detections of the nine inorganic constituents 

with concentrations less than the SRL were flagged with a 
14 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

less than or equal to symbol (≤) in this report because the 

concentrations of these constituents could be less than or equal 

to the reported value (see table A3 and additional discussion in 

the appendix section titled “Field Blank Samples”). Variability 

for more than 99 percent of the replicate sample pairs for 

constituents detected in samples was within the acceptable 

limits. Results from the replicate sample pairs confirm that 

the procedures used to collect, process, and analyze the 

samples did not introduce unacceptable levels of variability 

(see tables A4A–D and additional discussion in the appendix 

section titled “Replicate Sample Pairs”). Median matrix-spike 

sample recoveries for 17 of the 148 organic constituents 

analyzed were less than the acceptable range of between 

70 and 130 percent. Some constituents with low recoveries 

might not have been detected in some samples if they were 

present at concentrations near the laboratory reporting levels 

(LRLs). Exceptions include deethylatrazine (2-chloro-4-

isopropylamino-6-amino-s-triazine) and hexazinone, both 

of which had low median matrix-spike recoveries and were 

detected in groundwater samples (see table A5B and additional 

discussion in the appendix section titled “Matrix-Spike 

Samples”).

Comparison Benchmarks

Concentrations of constituents detected in groundwater 

samples were compared with USEPA and CDPH regulatory 

and non-regulatory drinking-water health-based benchmarks 

and benchmarks established for aesthetic purposes 

(U.S. Environmental Protection Agency, 2008b, 2009; 

California Department of Public Health, 2010a, b). The 

chemical data presented in this report are meant to characterize 

the quality of the untreated groundwater within the primary 

aquifer system of the KLAM study unit and are not intended 

to represent the treated drinking water delivered to consumers 

by water purveyors. The chemical composition of treated 

drinking water may differ from untreated groundwater because 

treated drinking water may be subjected to disinfection, 

filtration, mixing with other waters, and (or) exposure to the 

atmosphere prior to its delivery to consumers. Comparisons 

of untreated groundwater to benchmarks are for illustrative 

purposes only and are not indicative of compliance or noncompliance with drinking-water regulations. Comparison 

benchmarks were selected in the following order of priority 

(for example, if a constituent had an MCL-CA and a HAL-US, 

the MCL-US was selected because it has higher priority). 

1. MCL–Maximum Contaminant Level. Legally 

enforceable standards that apply to public water systems 

and are designed to protect public health by limiting 

the levels of contaminants in drinking water. MCLs 

established by the USEPA are the minimum standards 

with which States are required to comply; however, 

individual States may choose to set more stringent 

standards. CDPH has established MCLs for additional 

constituents not regulated by the USEPA, as well as 

lowered the benchmark concentration for a number 

of constituents. In this report, a benchmark set by the 

USEPA and adopted by the CDPH is labeled “MCL-US,” 

and one set by CDPH that is more stringent than the 

MCL-US is labeled “MCL-CA.” Site owners are notified 

when constituents are detected at concentrations greater 

than an MCL-US or an MCL-CA benchmark in samples 

collected for the GAMA-PBP, but these detections do not 

constitute violations of CDPH regulations.

2. AL–Action Level. Legally enforceable standards that 

apply to public water systems and are designed to protect 

public health by limiting the levels of copper and lead 

in drinking water. Detections of copper or lead greater 

than the action-level benchmarks trigger requirements for 

mandatory water treatment to reduce the corrosiveness of 

water to water pipes. The action levels established by the 

USEPA and CDPH are the same; thus, the benchmarks are 

labeled “AL-US” in this report.

3. TT–Treatment Technique. A legally required process 

intended to reduce the level of a contaminant in drinking 

water. TT requires mandatory additional disinfection 

during water treatment when water delivered to 

consumers exceeds specified action levels. The action 

levels established by the USEPA and CDPH are the same, 

thus these benchmarks are labeled “TT-US” in this report.

4. SMCL–Secondary Maximum Contaminant Level. 

Non-enforceable standards applied to constituents that 

affect the aesthetic qualities of drinking water, such 

as taste, odor, and color, or the technical qualities of 

drinking water, such as scaling and staining. Both the 

USEPA and CDPH define SMCLs, but unlike MCLs, 

SMCLs established by the CDPH are not required to 

be at least as stringent as those established by USEPA. 

SMCLs established by the CDPH are used in this report 

(SMCL-CA). For chloride, sulfate, specific conductance, 

and TDS, CDPH defines a “recommended” and an 

“upper” SMCL-CA; detections of these constituents in 

groundwater samples were compared with both levels. 

The SMCL-US for these constituents corresponds to the 

recommended SMCL-CA. The SMCL-US is used for pH 

because no SMCL-CA has been defined.

5. NL–Notification Level. Health-based notification levels 

have been established by the CDPH (NL-CA) for some 

of the constituents in drinking water that lack MCLs. If a 

constituent is detected at concentrations greater than its 

NL-CA, California State law requires timely notification 

of local governing bodies and recommends consumer 

notification.

6. HAL–Lifetime Health Advisory Level. The maximum 

concentration of a constituent at which its presence in 

drinking water is not expected to cause any adverse 

carcinogenic effects for a lifetime of exposure. HALs are 

established by the USEPA (HAL-US) and are calculated 

assuming consumption of 2 liters (L) (2.1 quarts) of 
Water-Quality Results 15

water per day over a 70-year lifetime by a 70-kilogram 

(154-pound) adult and that 20 percent of a person’s 

exposure comes from drinking water.

7. RSD5–Risk-Specific Dose. The concentration of a 

constituent in drinking water corresponding to an excess 

estimated lifetime cancer risk of 1 in 100,000. RSD5 

is an acronym for risk-specific dose at the 10–5 risk 

level. RSD5s are calculated by dividing the 10–4 cancerrisk concentration established by the USEPA by 10 

(RSD5-US).

The comparison benchmarks used in this report are 

listed in tables 3A–I for all constituents and in tables 4–14 for 

constituents detected in groundwater samples from the KLAM 

study unit. Not all constituents analyzed for this study have 

established benchmarks available. Detections of constituents 

at concentrations greater than the selected comparison 

benchmark are marked with asterisk (*) in tables 4, 7, 9, 

and 10. 

Water-Quality Results 

Results from analyses of groundwater samples from the 

KLAM study unit are presented in tables 4–14. Groundwater 

samples collected in the KLAM study unit were analyzed for 

up to 220 unique constituents; 137 of those were not detected 

in any of the samples, and 83 constituents were detected 

(tables 3A–I, 4). 

Water-quality indicators measured in the field and at the 

NWQL are summarized in table 4. The results of groundwater 

analyses organized by compound classes are presented in 

tables 5–14: 

• Organic constituents

• Volatile organic compounds (table 5)

• Pesticides and pesticide degradates (table 6)

• Inorganic constituents

• Trace elements (table 7)

• Nutrients (table 8)

• Major and minor ions, silica, and TDS (table 9)

• Arsenic and iron species (table 10)

• Isotopic tracers (table 11)

• Tritium, dissolved noble gases, and helium isotope 

ratios (table 12)

• Uranium and other radioactive constituents (table 13)

• Microbial indicators (table 14)

Water-Quality Indicators (Field and Laboratory)

Measurements of dissolved oxygen, pH, specific 

conductance, alkalinity, and associated parameters (water 

temperature and bicarbonate and carbonate concentrations) are 

presented in table 4. Dissolved oxygen, alkalinity, bicarbonate, 

and carbonate concentrations are used as indicators of natural 

processes that affect water chemistry. 

The pH value indicates the acidity of the water. Low 

pH in water may contribute to corrosion of pipes, and high 

pH in water may contribute to scaling. Field pH values for 

9 of the 38 of the grid sites sampled in the KLAM study unit 

were outside of the SMCL-US range for pH (< 6.5 or > 8.5) 

(table 4). Laboratory pH values for three of the grid sites 

were outside of the SMCL-US range for pH. Laboratory pH 

values may be dissimilar to field pH values because the pH 

of groundwater may change upon removal from the ambient 

environment and exposure to the atmosphere; therefore, the 

field measurements are preferred over the laboratory results.

Specific conductance is the measure of electrical 

conductivity of the water and is proportional to the amount 

of dissolved solids in the water. Field and laboratory specificconductance values for 1 of the 38 grid sites sampled 

were greater than the upper SMCL-CA benchmark of 

1,600 microsiemens per centimeter at 25 degrees Celsius 

(μS/cm at 25 °C) (table 4). 

Organic Constituents

VOCs are present in paints, solvents, fuels, fuel additives, 

refrigerants, fumigants, and disinfected water, and are 

characterized by their tendency to evaporate. VOCs generally 

persist longer in groundwater than in surface water because 

groundwater is isolated from the atmosphere. 

Of the 85 VOCs analyzed in the KLAM study unit, 

10 were detected in groundwater samples; all concentrations 

were less than health-based benchmarks (table 5). One 

or more VOCs were detected in 16 of the 38 grid sites 

sampled (about 42 percent detection frequency). Chloroform 

(trichloromethane) was the only VOC detected in more 

than 10 percent of the grid sites in the KLAM study unit. 

Chloroform is among the most commonly detected VOCs in 

groundwater nationally (Zogorski and others, 2006).

Pesticides (herbicides, insecticides, and fungicides) 

are chemicals used to control weeds, insects, fungi, and 

other pests in agricultural, urban, and suburban settings. 

Pesticide degradates are the product of the environmental 

transformations of the parent pesticide, and they can have 

similar properties to the parent pesticide (Andreu and Pico, 

2004).

Of the 83 pesticides and pesticide degradates analyzed 

in the KLAM study unit, 4 were detected in groundwater 

samples (deethylatrazine, atrazine, simazine, and hexazinone); 

all concentrations were less than health-based benchmarks 

(table 6). One or more pesticide compounds were detected 
16 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

in 8 of the 39 grid sites sampled (about 21 percent detection 

frequency). Deethylatrazine, a degradate of atrazine, was 

detected in more than 10 percent of the grid sites in the KLAM 

study unit. Deethylatrazine, simazine, and atrazine are among 

the Nation’s most commonly detected pesticide compounds in 

groundwater (Gilliom and others, 2006). 

Inorganic Constituents

Health-based or non-health-based benchmarks have been 

established for 22 of 25 trace elements analyzed in this study 

(tables 3D, F). Of the 18 trace elements with health-based 

benchmarks, all detected concentrations at the sites sampled in 

the KLAM study unit were less than established benchmarks, 

with the exception of one detection of boron that was greater 

than the NL-CA of 1,000 micrograms per liter (μg/L) 

(KLAM-06; table 7).

Nutrients (nitrogen and phosphorus) present in 

groundwater can affect biological activity in aquifers and 

in surface-water bodies that receive groundwater discharge. 

Inorganic nitrogen may be present in the form of ammonia, 

nitrite, or nitrate, depending on the oxidation-reduction state of 

the groundwater. All concentrations of nutrients measured in 

the KLAM study unit were less than health-based benchmarks 

(table 8).

The CDPH has established non-health-based secondary 

benchmarks (SMCL-CAs) that are based on aesthetic 

properties (such as taste, color, and odor) and technical 

properties (such as scaling and staining) of water, rather than 

on human-health concerns for iron, manganese, silver, zinc, 

chloride, sulfate, and TDS. 

Iron and manganese are trace elements whose 

concentrations are affected by the oxidation-reduction state 

of the groundwater. Precipitation of minerals containing iron 

or manganese may cause orange, brown, or black staining 

of surfaces. Iron concentrations greater than the SMCL-CA 

of 300 μg/L were detected in samples from three grid sites, 

and manganese concentrations greater than the SMCL-CA 

of 50 μg/L were detected in samples from four grid sites. 

Chloride and TDS were both detected at a concentration 

greater than their recommended SMCL-CA benchmarks 

(250 mg/L and 500 mg/L, respectively) in a sample from 

one grid site (table 9). Additionally, all silver and zinc 

concentrations detected in samples from KLAM study unit 

sites were less than the corresponding SMCL-CA benchmarks 

(table 7).

Arsenic and iron occur as different species depending 

on the oxidation–reduction state of the groundwater. The 

characterization of oxidized and reduced species of each of 

these elements in groundwater and the relative proportions of 

the oxidized and reduced species of each element can be used 

in the interpretation of the oxidation–reduction conditions of 

the aquifer. 

Concentrations of total arsenic and total iron reported 

by the NWQL in table 7 are considered to be more accurate 

than the concentrations reported by the USGS National 

Research Program (NRP) Trace Metal Laboratory (TML), 

Boulder, Colorado, in table 10 (see the appendix section 

titled “Constituents Determined by Multiple Methods or 

Laboratories”). Total iron concentrations (reported from the 

USGS NRP-TML) greater than the SMCL-CA of 300 μg/L 

were detected in samples from three grid sites (table 10).

Isotopic Tracers and Dissolved Noble Gases

The isotopic ratios, activities, and concentrations of many 

elements are used as tracers of hydrologic processes. Stable 

isotope ratios of hydrogen (δ2H) and oxygen (δ18O) in water aid 

in the interpretation of the sources of groundwater recharge. 

These stable-isotope ratios reflect the altitude, latitude, and 

signature precipitation and can also be used to evaluate the 

extent of evaporation of water (Clark and Fritz, 1997). In the 

KLAM study unit, the stable-isotope ratios of hydrogen ranged 

from –104 to –57.8 per mil, and the stable isotope ratios of 

oxygen ranged from –14.41 to –8.75 per mil (table 11).

Isotopic ratios of strontium (87Sr/86Sr) in water reflect 

the amounts of strontium (and other inorganic constituents) 

the aquifer materials are contributing to the groundwater 

system. In regions that have diverse geology, isotopic ratios 

of strontium may aid in identifying groundwater-flow paths 

(Clark and Fritz, 1997). The isotopic ratios of strontium 

ranged from 0.70405 to 0.71348 (table 11).

Tritium activities and helium isotope ratios provide 

information about the age (time since recharge) of 

groundwater. Tritium is a short-lived radioactive isotope of 

hydrogen that is incorporated into the water molecule. Low 

levels of tritium are produced continuously by interaction 

of cosmic radiation with the Earth’s atmosphere, and a large 

amount of tritium was produced as a result of atmospheric 

testing of nuclear weapons between 1952 and 1963. Thus, 

concentrations of tritium greater than background levels 

generally indicate the presence of water recharged since the 

early 1950s. Helium isotope ratios can be used in conjunction 

with tritium concentrations to estimate ages for young 

groundwater (Clark and Fritz, 1997). Of the isotopic tracer 

constituents analyzed for this study, tritium is the only one 

with a health-based benchmark. All measured tritium activities 

in samples from the sites in the KLAM study unit were 

more than three orders of magnitude less than the MCL-CA 

benchmark (tables 12 and 13).

Carbon-14, a radioactive isotope of carbon, is an 

age-dating tracer. Low levels of carbon-14 are produced 

continuously by interaction of cosmic radiation with the 

Earth’s atmosphere and are incorporated into atmospheric 

carbon dioxide. Carbon dioxide dissolves in precipitation, 

surface water, and groundwater exposed to the atmosphere, 

thereby entering the hydrologic cycle. Because carbon-14 
Summary 17

decays with a half-life of approximately 5,700 years, low 

activities of carbon-14, relative to modern values, generally 

indicate a presence of groundwater that is several thousands of 

years old or more (Clark and Fritz, 1997). Carbon-14 activities 

ranged from 38.86 to 110.6 percent modern carbon, and the 

stable isotopes of carbon (δ13C) in dissolved inorganic carbon 

ranged from –21.74 to –11.15 per mil (table 11).

Gases dissolve in water that is in contact with the 

atmosphere, and the solubilities of the different gas species 

vary with temperature. Concentrations of dissolved noble 

gases are used to estimate the conditions of groundwater 

recharge, particularly the temperature of the water at the time 

of recharge (Clark and Fritz, 1997). Dissolved noble gas 

concentrations and the estimated temperature of the water at 

the time of recharge are presented in table 12.

Uranium and Other Radioactive Constituents

Radioactivity is the release of energy or energetic 

particles during changes in the structure of the nucleus of an 

atom. Most radioactivity in groundwater comes from decay of 

naturally occurring isotopes such as uranium and thorium that 

are present in minerals in the sediments or fractured rocks of 

the aquifer. Uranium and thorium decay in a series of steps, 

eventually forming stable isotopes of lead (Soddy, 1913; 

Faure and Mensing, 2005). Radon-222 is a radioactive isotope 

formed during the uranium or thorium decay series. In each 

step in the decay series, one radioactive element turns into a 

different radioactive element by emitting an alpha or a beta 

particle from its nucleus. For example, radium-226 emits an 

alpha particle and therefore turns into radon-222. Radium-228 

decays to form actinium-228 by emission of a beta particle. 

The alpha and beta particles emitted during radioactive 

decay are hazardous to human health because these energetic 

particles may damage cells. Radiation damage to cell DNA 

may increase the risk of getting cancer. 

All measured activities of uranium, radon-222, and gross 

alpha and gross beta radioactivity in samples from the sites in 

the KLAM study unit were less than health-based benchmarks 

(table 13). 

Microbial Indicators

Water is disinfected during drinking-water treatment 

to prevent diseases that may be spread by water-borne 

microbial constituents derived from human or animal wastes. 

The specific bacteria responsible for diseases generally are 

not measured because routine analytical methods are cost 

prohibitive. Measurements are made of more easily analyzed 

microbial constituents that serve as indicators of the presence 

of human or animal waste in water. 

The presence of total coliform (a bacterial indicator) was 

detected in 14 of the 38 grid sites in the KLAM study unit. In 

addition, Escherichia coli (E. coli) (a bacterial indicator) was 

detected in samples from 2 of these 14 grid sites (table 14). 

Future Work

Subsequent reports for the KLAM study unit will be 

focused on assessment of the data presented in this report by 

using statistical, qualitative, and quantitative approaches to 

evaluate the natural and human factors affecting groundwater 

quality in the KLAM study unit. Water-quality data contained 

in the CDPH databases will be used in combination with the 

data that are presented in this report. 

Summary 

Groundwater quality in the 8,806-square-mile 

Klamath Mountains (KLAM) study unit was investigated 

by the U.S. Geological Survey (USGS) from October to 

December 2010, as part of the Priority Basin Project (PBP) of 

the California State Water Resources Control Board (SWRCB) 

Groundwater Ambient Monitoring and Assessment (GAMA) 

Program. The GAMA Program was created to provide a 

comprehensive baseline of groundwater quality in the State. 

The GAMA-PBP was created as a result of the Groundwater 

Quality Monitoring Act of 2001 (Sections 10780–10782.3 of 

the California Water Code, Assembly Bill 599) to assess and 

monitor the quality of groundwater. The GAMA-PBP is being 

conducted by the USGS in cooperation with the SWRCB and 

Lawrence Livermore National Laboratory (LLNL).

The GAMA Klamath Mountains study was designed 

to provide a spatially unbiased assessment of untreatedgroundwater quality in the primary aquifer system and to 

facilitate statistically consistent comparisons of untreatedgroundwater quality throughout California. The primary 

aquifer system is defined by the perforation intervals of wells 

listed in the California Department of Public Health (CDPH) 

database for the KLAM study unit. The quality of groundwater 

in the primary aquifer system may differ from shallow or 

deep water-bearing zones; shallow groundwater may be more 

vulnerable to surficial contamination.

This study did not evaluate the quality of water delivered 

to consumers; after withdrawal from the ground, water 

typically is treated, disinfected, and blended with other 

waters to maintain acceptable water quality. The benchmarks 

used in this report apply to treated water that is served to 

the consumer, not to untreated groundwater. However, to 

provide context for the results, concentrations of constituents 

measured in these groundwater samples were compared with 

benchmarks established by the U.S. Environmental Protection 

Agency (USEPA) and the CDPH.

The KLAM study unit is located within the Klamath 

Mountains hydrologic province and included assessment of 

the groundwater quality from 39 sites in Del Norte, Humboldt, 

Siskiyou, Tehama, Trinity, and Shasta Counties, California. 

A total of 38 sites were selected by using a randomized grid 

approach to achieve statistically unbiased representation of 

groundwater used for public drinking-water supplies (grid 
18 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

sites). In addition, one non-randomized site was sampled 

(understanding site). 

Groundwater samples were analyzed for water-quality 

indicators, organic constituents, inorganic constituents, 

and uranium and other radioactive constituents. Isotopic 

tracers and dissolved gases also were measured to provide a 

dataset that will be used to interpret the sources and ages of 

groundwater. In total, 213 unique constituents and 7 waterquality indicators were measured. This report describes the 

sampling, analytical, and quality-assurance methods used in 

the study, and presents the results of the chemical analyses of 

the groundwater samples.

Quality-control samples (field blanks, replicate sample 

pairs, and matrix spikes) were collected at 13 percent of 

the sites in the KLAM study unit, and the results for these 

samples were used to evaluate the quality of the data for the 

groundwater samples. Field blank samples rarely contained 

detectable concentrations of any constituent. Replicate pair 

samples were generally within acceptable limits of variability, 

and matrix-spike sample recoveries were largely within the 

acceptable range.

All detections of organic constituents, inorganic 

constituents, uranium and other radioactive constituents, and 

microbial indicators from the 39 sites sampled in the KLAM 

study unit were less than health-based benchmarks, with the 

exception of one detection of boron greater than the CDPH 

notification level of 1,000 micrograms per liter (μg/L). 

Chloride and total dissolved solids (TDS) concentrations 

did not exceed the upper non-health-based benchmarks 

in groundwater sampled as part of this study; however, 

concentrations of iron and manganese were measured 

at concentrations greater than the corresponding CDPH 

secondary maximum contaminant levels (SMCL-CAs). 

Acknowledgments

The authors thank the following cooperators for their 

support: the California State Water Resources Control 

Board, California Department of Public Health, California 

Department of Water Resources, and Lawrence Livermore 

National Laboratory. We especially thank the property owners 

and water purveyors for allowing the U.S. Geological Survey 

to collect samples from their wells and springs.

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Tables 25

Tables Table 1. Identification, sampling, and construction information for sites sampled for the Klamath Mountains (KLAM) Groundwater 

Ambient Monitoring and Assessment (GAMA) study unit, California, October to December 2010.

[Sampling schedule is described in table 2. Land-surface datum (LSD) is a datum plane that is approximately at land surface at each well. The altitude of the 

LSD is described in feet above the North American Vertical Datum of 1988 (NAVD 88). GAMA site identification number: KLAM, Klamath Mountains study 

unit; KLAM-U, Klamath Mountains study unit understanding site. Other abbreviations: ft, feet; na, not available]

GAMA site 

identification 

number

Sampling information Construction information

Date sampled 

(mm/dd/yyyy) Site type Altitude of LSD 

(ft above NAVD 88)

Well depth 

(ft below LSD)

Depth to top perforation 

(ft below LSD)

Depth to bottom perforation 

(ft below LSD)

KLAM grid sites (38 sites sampled)

KLAM-01 10/18/2010 Spring 723 at LSD at LSD at LSD

KLAM-02 10/19/2010 Spring 3,043 at LSD at LSD at LSD

KLAM-03 10/19/2010 Production 1,977 32 24 32

KLAM-04 10/20/2010 Spring 4,745 at LSD at LSD at LSD

KLAM-05 10/20/2010 Production 2,989 80 57 80

KLAM-06 10/21/2010 Production 2,324 270 170 270

KLAM-07 10/21/2010 Production 2,235 na na na

KLAM-08 11/1/2010 Production 2,152 180 0 180

KLAM-09 11/1/2010 Production 713 48 36 48

KLAM-10 11/2/2010 Spring 1,063 at LSD at LSD at LSD

KLAM-11 11/2/2010 Production 647 89 49 89

KLAM-12 11/3/2010 Spring 2,655 at LSD at LSD at LSD

KLAM-13 11/3/2010 Production 1,412 45 na na

KLAM-14 11/4/2010 Production 1,270 na na na

KLAM-15 11/4/2010 Production 1,140 na na na

KLAM-16 11/15/2010 Production 1,120 278 55 278

KLAM-17 11/15/2010 Production 3,321 na na na

KLAM-18 11/16/2010 Production 3,301 300 240 300

KLAM-19 11/16/2010 Production 1,788 80 na na

KLAM-20 11/17/2010 Spring 2,465 at LSD at LSD at LSD

KLAM-21 11/17/2010 Production 2,620 225 na na

KLAM-22 11/18/2010 Production 457 44 na na

KLAM-23 11/18/2010 Production 1,794 305 160 305

KLAM-24 11/29/2010 Production 3,436 na na na

KLAM-25 11/30/2010 Production 1,085 125 na na

KLAM-26 11/30/2010 Production 1,093 90 70 90

KLAM-27 12/1/2010 Production 1,143 320 300 320

KLAM-28 12/1/2010 Production 1,091 112 68 112

KLAM-29 12/2/2010 Spring 2,611 at LSD at LSD at LSD

KLAM-30 12/2/2010 Production 2,008 120 60 120
26 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

GAMA site 

identification 

number

Sampling information Construction information

Date sampled 

(mm/dd/yyyy) Site type Altitude of LSD 

(ft above NAVD 88)

Well depth 

(ft below LSD)

Depth to top perforation 

(ft below LSD)

Depth to bottom perforation 

(ft below LSD)

KLAM grid sites (38 sites sampled)—Continued

KLAM-31 12/6/2010 Production 3,971 na na na

KLAM-32 12/7/2010 Production 1,416 227 187 227

KLAM-33 12/7/2010 Production 1,250 249 201 249

KLAM-34 12/8/2010 Production 903 177 77 177

KLAM-35 12/8/2010 Production 1,331 na na na

KLAM-36 12/9/2010 Production 2,479 25 na na

KLAM-37 12/13/2010 Production 1,926 na na na

KLAM-38 12/14/2010 Production 1,970 na na na

KLAM understanding site 

KLAM-U-01 12/14/2010 Production 1,185 na na na

Table 1. Identification, sampling, and construction information for sites sampled for the Klamath Mountains (KLAM) Groundwater 

Ambient Monitoring and Assessment (GAMA) study unit, California, October to December 2010.—Continued

[Sampling schedule is described in table 2. Land-surface datum (LSD) is a datum plane that is approximately at land surface at each well. The altitude of the 

LSD is described in feet above the North American Vertical Datum of 1988 (NAVD 88). GAMA site identification number: KLAM, Klamath Mountains study 

unit; KLAM-U, Klamath Mountains study unit understanding site. Other abbreviations: ft, feet; na, not available]

Tables
Tables 27

Table 2. Classes of chemical constituents and field water-quality indicators collected for the Klamath Mountains (KLAM) Groundwater 

Ambient Monitoring and Assessment (GAMA) study unit, California, October to December 2010.

[Abbreviations: VOC, volatile organic compound; TDS, total dissolved solids; LLNL, Lawrence Livermore National Laboratory, Livermore, California]

Constituent 

classes

Constituent 

list table

Results 

table

Field water-quality indicators 

Dissolved oxygen, temperature, pH, and specific conductance no table 4

Field alkalinity, bicarbonate, and carbonate no table 4

Organic constituents

VOCs 3A 5

Pesticides and pesticide degradates 3B 6

Constituent of special interest

Perchlorate 3C none 1

Inorganic constituents

Trace elements 3D 7

Nutrients 3E 8

Major and minor ions, silica, and TDS 3F 9

Laboratory alkalinity, bicarbonate, and carbonate 3F 4

Arsenic and iron species 3G 10

Isotopic tracers and dissolved noble gases

Stable isotopes of hydrogen and oxygen in water 3H 11

Isotopic ratios of strontium in water 3H 11

Stable isotopes of carbon in dissolved inorganic carbon and carbon-14 abundance 3H 11

Dissolved noble gases and helium isotope ratios 3H 12

Uranium and other radioactive constituents

Uranium 3H 13

Radon-222 3H 13

Gross alpha and gross beta radioactivity (72-hour and 30-day counts) 3H 13

Tritium (LLNL) 3H 12

Tritium 3H 13

Microbial constituents

Escherichia coli (E.coli) and total coliform 3I 14

1

 Perchlorate data did not meet quality-control standards as required by the GAMA Program; therefore, data are not presented. Please see the appendix section 

titled “Other Quality-Control Results” for more information.
28 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Table 3A. Volatile organic compounds, primary uses or sources, comparison benchmarks, and reporting information for the 

U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) Schedule 2020.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. LRL, benchmark type, and benchmark level as of October 1, 

2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA 

when the MCL-CA is lower than the MCL-US or no MCL-US exists. HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory level; 

MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant level; NL-CA, CDPH 

notification level; RSD5-US, USEPA risk-specific dose at a risk factor of 10–5. Other abbreviations: CAS, Chemical Abstracts Service; CASRN, Chemical 

Abstract Service Registry Number; LRL, laboratory reporting level; SRL, study reporting level; THM, trihalomethane; D, detected in groundwater samples 

(table 5); na, not available; μg/L, micrograms per liter; —, not detected]

Constituent (synonym or 

abbreviation) Primary use or source

USGS 

parameter 

code

CASRN 1 LRL or SRL 

(μg/L)

Benchmark 

type

Benchmark 

level 

(μg/L)

Detection

Acetone Solvent 81552 67-64-1 3.4 na na —

Acrylonitrile Organic synthesis 34215 107-13-1 0.8 RSD5-US 0.6 —

tert-Amyl methyl ether (TAME) Gasoline oxygenate 50005 994-05-8 0.06 na na —

Benzene Gasoline hydrocarbon 34030 71-43-2 0.026 MCL-CA 1 —

Bromobenzene Solvent 81555 108-86-1 0.022 na na —

Bromochloromethane Fire retardant 77297 74-97-5 0.06 HAL-US 90 —

Bromodichloromethane Disinfection byproduct (THM) 32101 75-27-4 0.034 MCL-US 3

 80 D

Bromoform 

(Tribromomethane)

Disinfection byproduct (THM) 32104 75-25-2 0.1 MCL-US 3

 80 —

Bromomethane 

(Methyl bromide)

Fumigant 34413 74-83-9 0.2 HAL-US 10 —

n-Butylbenzene Gasoline hydrocarbon 77342 104-51-8 0.08 NL-CA 260 —

sec-Butylbenzene Gasoline hydrocarbon 77350 135-98-8 0.034 NL-CA 260 —

tert-Butylbenzene Gasoline hydrocarbon 77353 98-06-6 0.06 NL-CA 260 —

Carbon disulfide Organic synthesis 77041 75-15-0 0.08 NL-CA 160 D

Carbon tetrachloride 

(Tetrachloromethane)

Solvent 32102 56-23-5 0.06 MCL-CA 0.5 —

Chlorobenzene Solvent 34301 108-90-7 0.026 MCL-CA 70 —

Chloroethane Solvent 34311 75-00-3 0.06 na na —

Chloroform 

(Trichloromethane)

Disinfection byproduct (THM) 32106 67-66-3 0.03 MCL-US 3

 80 D

Chloromethane Solvent 34418 74-87-3 0.14 HAL-US 30 —

3-Chloropropene Organic synthesis 78109 107-05-1 0.08 na na —

2-Chlorotoluene Solvent 77275 95-49-8 0.028 NL-CA 140 —

4-Chlorotoluene Solvent 77277 106-43-4 0.042 NL-CA 140 —

Dibromochloromethane Disinfection byproduct (THM) 32105 124-48-1 0.12 MCL-US 3

 80 D

1,2-Dibromo-3-chloropropane 

(DBCP)

Fumigant 82625 96-12-8 0.4 MCL-US 0.2 —

1,2-Dibromoethane (EDB) Fumigant 77651 106-93-4 0.028 MCL-US 0.05 —

Dibromomethane Solvent 30217 74-95-3 0.05 na na —

1,2-Dichlorobenzene Solvent 34536 95-50-1 0.028 MCL-CA 600 —

1,3-Dichlorobenzene Solvent 34566 541-73-1 0.024 HAL-US 600 —

1,4-Dichlorobenzene Fumigant 34571 106-46-7 0.026 MCL-CA 5 —

trans-1,4-Dichloro-2-butene Organic synthesis 73547 110-57-6 0.36 na na —

Dichlorodifluoromethane 

(CFC-12)

Refrigerant 34668 75-71-8 0.1 NL-CA 1,000 —
Tables 29

Constituent (synonym or 

abbreviation) Primary use or source

USGS 

parameter 

code

CASRN 1 LRL or SRL 

(μg/L)

Benchmark 

type

Benchmark 

level 

(μg/L)

Detection

1,1-Dichloroethane 

(1,1-DCA)

Solvent 34496 75-34-3 0.044 MCL-CA 5 —

1,2-Dichloroethane 

(1,2-DCA)

Solvent 32103 107-06-2 0.08 MCL-CA 0.5 —

1,1-Dichloroethene (1,1-DCE) Organic synthesis 34501 75-35-4 0.022 MCL-CA 6 —

cis-1,2-Dichloroethene 

(cis-1,2-DCE)

Solvent 77093 156-59-2 0.022 MCL-CA 6 —

trans-1,2-Dichloroethene (trans1,2-DCE)

Solvent 34546 156-60-5 0.018 MCL-CA 10 —

1,2-Dichloropropane Fumigant 34541 78-87-5 0.026 MCL-US 5 —

1,3-Dichloropropane Fumigant 77173 142-28-9 0.06 na na —

2,2-Dichloropropane Fumigant 77170 594-20-7 0.06 na na —

1,1-Dichloropropene Organic synthesis 77168 563-58-6 0.04 na na —

cis-1,3-Dichloropropene Fumigant 34704 10061-01-5 0.1 RSD5-US 4

 4 —

trans-1,3-Dichloropropene Fumigant 34699 10061-02-6 0.14 RSD5-US 4

 4 —

Diethyl ether Solvent 81576 60-29-7 0.1 na na —

Diisopropyl ether (DIPE) Gasoline oxygenate 81577 108-20-3 0.06 na na —

Ethylbenzene Gasoline hydrocarbon 34371 100-41-4 0.036 MCL-CA 300 —

Ethyl tert-butyl ether (ETBE) Gasoline oxygenate 50004 637-92-3 0.032 na na —

Ethyl methacrylate Organic synthesis 73570 97-63-2 0.2 na na —

o-Ethyl toluene 

(1-Ethyl-2-methyl benzene)

Gasoline hydrocarbon 77220 611-14-3 0.032 na na —

Hexachlorobutadiene Organic synthesis 39702 87-68-3 0.08 RSD5-US 9 —

Hexachloroethane Solvent 34396 67-72-1 0.22 HAL-US 1 —

2-Hexanone 

(n-Butyl methyl ketone)

Solvent 77103 591-78-6 0.4 na na —

Iodomethane (Methyl iodide) Organic synthesis 77424 74-88-4 0.26 na na —

Isopropylbenzene Gasoline hydrocarbon 77223 98-82-8 0.042 NL-CA 770 —

4-Isopropyl-1-methyl benzene Gasoline hydrocarbon 77356 99-87-6 0.06 na na —

Methyl acrylate Organic synthesis 49991 96-33-3 0.22 na na —

Methyl acrylonitrile Organic synthesis 81593 126-98-7 0.26 na na —

Methyl tert-butyl ether (MTBE) Gasoline oxygenate 78032 1634-04-4 0.1 MCL-CA 13 D

Methyl iso-butyl ketone (MIBK) Solvent 78133 108-10-1 0.32 NL-CA 120 —

Methylene chloride 

(Dichloromethane)

Solvent 34423 75-09-2 0.04 MCL-US 5 —

Methyl ethyl ketone 

(2-butanone, MEK)

Solvent 81595 78-93-3 1.6 HAL-US 4,000 D

Table 3A. Volatile organic compounds, primary uses or sources, comparison benchmarks, and reporting information for the 

U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) Schedule 2020.—Continued

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. LRL, benchmark type, and benchmark level as of October 1, 

2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA 

when the MCL-CA is lower than the MCL-US or no MCL-US exists. HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory level; 

MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant level; NL-CA, CDPH 

notification level; RSD5-US, USEPA risk-specific dose at a risk factor of 10–5. Other abbreviations: CAS, Chemical Abstracts Service; CASRN, Chemical 

Abstract Service Registry Number; LRL, laboratory reporting level; SRL, study reporting level; THM, trihalomethane; D, detected in groundwater samples 

(table 5); na, not available; μg/L, micrograms per liter; —, not detected]
30 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Constituent (synonym or 

abbreviation) Primary use or source

USGS 

parameter 

code

CASRN 1 LRL or SRL 

(μg/L)

Benchmark 

type

Benchmark 

level 

(μg/L)

Detection

Methyl methacrylate Organic synthesis 81597 80-62-6 0.22 na na —

Naphthalene Gasoline hydrocarbon 34696 91-20-3 0.18 NL-CA 17 —

Perchloroethene 

(PCE, Tetrachloroethene)

Solvent 34475 127-18-4 0.026 MCL-US 5 D

n-Propylbenzene Solvent 77224 103-65-1 0.036 NL-CA 260 —

Styrene Gasoline hydrocarbon 77128 100-42-5 0.042 MCL-US 100 D

1,1,1,2-Tetrachloroethane Solvent 77562 630-20-6 0.04 HAL-US 70 —

1,1,2,2-Tetrachloroethane Solvent 34516 79-34-5 0.14 MCL-CA 1 —

Tetrahydrofuran Solvent 81607 109-99-9 all data 2 na na —

1,2,3,4-Tetramethylbenzene Gasoline hydrocarbon 49999 488-23-3 0.1 na na —

1,2,3,5-Tetramethylbenzene Gasoline hydrocarbon 50000 527-53-7 0.08 na na —

Toluene Gasoline hydrocarbon 34010 108-88-3 2

 0.69 MCL-CA 150 D

1,2,3-Trichlorobenzene Organic synthesis 77613 87-61-6 0.06 na na —

1,2,4-Trichlorobenzene Solvent 34551 120-82-1 0.08 MCL-CA 5 —

1,1,1-Trichloroethane 

(1,1,1-TCA)

Solvent 34506 71-55-6 0.03 MCL-CA 200 —

1,1,2-Trichloroethane 

(1,1,2-TCA)

Solvent 34511 79-00-5 0.028 MCL-CA 5 —

Trichloroethene (TCE) Solvent 39180 79-01-6 0.022 MCL-US 5 D

Trichlorofluoromethane (CFC-11) Refrigerant 34488 75-69-4 0.06 MCL-CA 150 —

1,2,3-Trichloropropane 

(1,2,3-TCP)

Solvent/organic synthesis 77443 96-18-4 0.12 HAL-US 40 —

Trichlorotrifluoroethane (CFC113)Refrigerant 77652 76-13-1 0.034 MCL-CA 1,200 —

1,2,3-Trimethylbenzene Gasoline hydrocarbon 77221 526-73-8 0.06 na na —

1,2,4-Trimethylbenzene Gasoline hydrocarbon 77222 95-63-6 2

 0.56 NL-CA 330 —

1,3,5-Trimethylbenzene Organic synthesis 77226 108-67-8 0.032 NL-CA 330 —

Vinyl bromide (Bromoethene) Fire retardant 50002 593-60-2 0.12 na na —

Vinyl chloride (Chloroethene) Organic synthesis 39175 75-01-4 0.06 MCL-CA 0.5 —

m- plus p-Xylene Gasoline hydrocarbon 85795 108-38-3 / 

106-42-3

0.08 MCL-CA 5

 1,750 —

o-Xylene Gasoline hydrocarbon 77135 95-47-6 0.032 MCL-CA 5

 1,750 —

1

 This report contains CASRNs®, which is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs 

through CAS Client ServicesSM.

2

 The SRL was defined by Fram and others (2012).

3

 The MCL-US benchmark for trihalomethanes is the sum of chloroform, bromoform, bromodichloromethane, and dibromochloromethane.

4

 The RSD5 benchmark for 1,3-dichloropropene is the sum of its isomers (cis and trans).

5

 The MCL-CA benchmarks for m- plus p-xylene and o-xylene is the sum of all three xylene compounds.

Table 3A. Volatile organic compounds, primary uses or sources, comparison benchmarks, and reporting information for the 

U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) Schedule 2020.—Continued

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. LRL, benchmark type, and benchmark level as of October 1, 

2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA 

when the MCL-CA is lower than the MCL-US or no MCL-US exists. HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory level; 

MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant level; NL-CA, CDPH 

notification level; RSD5-US, USEPA risk-specific dose at a risk factor of 10–5. Other abbreviations: CAS, Chemical Abstracts Service; CASRN, Chemical 

Abstract Service Registry Number; LRL, laboratory reporting level; SRL, study reporting level; THM, trihalomethane; D, detected in groundwater samples 

(table 5); na, not available; μg/L, micrograms per liter; —, not detected]
Table 3B. Pesticides and pesticide degradates, primary uses or sources, comparison benchmarks, and reporting information for the USGS National Schedule 2003.[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. LRL, benchmark type, and benchmark level as of October 1, 2010. Benchmalevel benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. HProtection Agency (USEPA) lifetime health advisory level; MCL-CA, California Department of Public Health maximum contaminant level; MCL-US, USEPA maximum contamrisk-specific dose at a risk factor of 10–5. Other abbreviations: CASRN, Chemical Abstract Service Registry Number; LRL, laboratory reporting level; D, detected in groundwa

available; μg/L, micrograms per liter; —, not detected]

Constituent 

(synonym or abbreviation) Primary use or source USGS parameter code CASRN LRL (μg/L) Benchmark type B

Acetochlor Herbicide 49260 34256-82-1 0.01 na 

Alachlor Herbicide 46342 15972-60-8 0.008 MCL-US 

Atrazine Herbicide 39632 1912-24-9 0.007 MCL-CA 

Azinphos-methyl Insecticide 82686 86-50-0 0.12 na 

Azinphos-methyl oxon Insecticide degradate 61635 961-22-8 0.042 na 

Benfluralin Herbicide 82673 1861-40-1 0.014 na 

Carbaryl Insecticide 82680 63-25-2 0.06 RSD5-US 

2-Chloro-2,6-diethylacetanilide Herbicide degradate 61618 6967-29-9 0.01 na 

4-Chloro-2-methylphenol Herbicide degradate 61633 1570-64-5 0.0046 na 

Chlorpyrifos Insecticide 38933 2921-88-2 0.0036 HAL-US 

Chlorpyrifos oxon Insecticide degradate 61636 5598-15-2 0.06 na 

Cyfluthrin Insecticide 61585 68359-37-5 0.016 na Cypermethrin Insecticide 61586 52315-07-8 0.02 na Dacthal (DCPA) Herbicide 82682 1861-32-1 0.0076 HAL-US 

Deethylatrazine (2-Chloro-4-isopropylamino-6-amino-s-triazine) Herbicide degradate 04040 6190-65-4 0.006 na 

Desulfinylfipronil Insecticide degradate 62170 na 0.012 na 

Desulfinylfipronil amide Insecticide degradate 62169 na 0.029 na 

Diazinon Insecticide 39572 333-41-5 0.006 HAL-US 

3,4-Dichloroaniline Herbicide degradate 61625 95-76-1 0.0042 na 

Dichlorvos Insecticide 38775 62-73-7 0.04 na 

Dicrotophos Insecticide 38454 141-66-2 0.08 na Dieldrin Insecticide 39381 60-57-1 0.008 RSD5-US 

2,6-Diethylaniline Herbicide degradate 82660 579-66-8 0.006 na 

Dimethoate Insecticide 82662 60-51-5 0.006 na 

Ethion Insecticide 82346 563-12-2 0.008 na Ethion monoxon Insecticide degradate 61644 17356-42-2 0.021 na 

2-Ethyl-6-methylaniline Herbicide degradate 61620 24549-06-2 0.01 na 

Fenamiphos Insecticide 61591 22224-92-6 0.03 HAL-US 
Constituent (synonym or abbreviation) Primary use or source USGS parameter code CASRN LRL (μg/L) Benchmark type B

Fenamiphos sulfone Insecticide degradate 61645 31972-44-8 0.054 na 

Fenamiphos sulfoxide Insecticide degradate 61646 31972-43-7 0.08 na 

Fipronil Insecticide 62166 120068-37-3 0.018 na 

Fipronil sulfide Insecticide degradate 62167 120067-83-6 0.012 na 

Fipronil sulfone Insecticide degradate 62168 120068-36-2 0.024 na 

Fonofos Insecticide 04095 944-22-9 0.0048 HAL-US 

Hexazinone Herbicide 04025 51235-04-2 0.008 HAL-US 

Iprodione Fungicide 61593 36734-19-7 0.014 na Isofenphos Insecticide 61594 25311-71-1 0.006 na 

Malaoxon Insecticide degradate 61652 1634-78-2 0.022 na 

Malathion Insecticide 39532 121-75-5 0.016 HAL-US 

Metalaxyl Fungicide 61596 57837-19-1 0.014 na 

Methidathion Insecticide 61598 950-37-8 0.012 na 

Metolachlor Herbicide 39415 51218-45-2 0.014 HAL-US 

Metribuzin Herbicide 82630 21087-64-9 0.012 HAL-US 

Myclobutanil Fungicide 61599 88671-89-0 0.01 na 

1-Naphthol Insecticide degradate 49295 90-15-3 0.036 na 

Paraoxon-methyl Insecticide degradate 61664 950-35-6 0.014 na Parathion-methyl Insecticide 82667 298-00-0 0.008 HAL-US 

Pendimethalin Herbicide 82683 40487-42-1 0.012 na 

cis-Permethrin Insecticide 82687 54774-45-7 0.01 na 

Phorate Insecticide 82664 298-02-2 0.02 na 

Phorate oxon Insecticide degradate 61666 2600-69-3 0.027 na 

Phosmet Insecticide 61601 732-11-6 0.14 na 

Phosmet oxon Insecticide degradate 61668 3735-33-9 0.0511 na Prometon Herbicide 04037 1610-18-0 0.012 HAL-US 

Prometryn Herbicide 04036 7287-19-6 0.006 na 

Pronamide (Propyzamide) Herbicide 82676 23950-58-5 0.0036 RSD5-US 

Table 3B. Pesticides and pesticide degradates, primary uses or sources, comparison benchmarks, and reporting information for the USGS National Schedule 2003.—Continued[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. LRL, benchmark type, and benchmark level as of October 1, 2010. Benchmalevel benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. HProtection Agency (USEPA) lifetime health advisory level; MCL-CA, California Department of Public Health maximum contaminant level; MCL-US, USEPA maximum contamrisk-specific dose at a risk factor of 10–5. Other abbreviations: CASRN, Chemical Abstract Service Registry Number; LRL, laboratory reporting level; D, detected in groundwa

available; μg/L, micrograms per liter; —, not detected]
Constituent 

(synonym or abbreviation) Primary use or source USGS parameter code CASRN LRL (μg/L) Benchmark type B

Simazine Herbicide 04035 122-34-9 0.006 MCL-US 

Tebuthiuron Herbicide 82670 34014-18-1 0.028 HAL-US 

Terbufos Insecticide 82675 13071-79-9 0.018 HAL-US 

Terbufos oxon sulfone Insecticide degradate 61674 56070-15-6 0.045 na 

Terbuthylazine Herbicide 04022 5915-41-3 0.006 na 

Tribufos Defoliant 61610 78-48-8 0.018 na 

Trifluralin Herbicide 82661 1582-09-8 0.018 HAL-US 

1 One or more median matrix-spike recoveries were less than 70 percent. Low recoveries may indicate that the compound might not have been detected in some samples if it w

concentrations.Table 3B. Pesticides and pesticide degradates, primary uses or sources, comparison benchmarks, and reporting information for the USGS National Schedule 2003.—Continued[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. LRL, benchmark type, and benchmark level as of October 1, 2010. Benchmalevel benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. HProtection Agency (USEPA) lifetime health advisory level; MCL-CA, California Department of Public Health maximum contaminant level; MCL-US, USEPA maximum contamrisk-specific dose at a risk factor of 10–5. Other abbreviations: CASRN, Chemical Abstract Service Registry Number; LRL, laboratory reporting level; D, detected in groundwa

available; μg/L, micrograms per liter; —, not detected]

Table 3C. Perchlorate, primary uses or source, comparison benchmark, and reporting information for Weck Laboratories, Inc. (Weck), City of Indust[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. MRL, benchmark type, and benchmark level as of October 1, 2010. Benchm

contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCLDepartment of Public Health maximum contaminant level. Other abbreviations: CASRN, Chemical Abstract Service Registry Number; MRL, minimum reporting level; μg/L, available]

Constituent 

(synonym or abbreviation)

Primary use 

or source

USGS 

parameter code CASRN MRL (μg/L) Benchmark type Benchmar

(μg/L

Perchlorate Rocket fuel, fireworks, flares 63790 14797-73-0 0.10 MCL-CA 6 

1 Perchlorate data did not meet quality-control standards as required by the GAMA Program; therefore, data are not presented. Please see the appendix section titled “Other Qu

information.
34 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Table 3D. Trace elements, comparison benchmarks, and reporting information for the U.S. Geological Survey (USGS) National Water 

Quality Laboratory (NWQL) Schedule 1948.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. LRL, benchmark type, and benchmark level as of October 1, 

2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA 

when the MCL-CA is lower than the MCL-US or no MCL-US exists. AL-US, U.S. Environmental Protection Agency (USEPA) action level; HAL-US, 

USEPA lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum 

contaminant level; NL-CA, CDPH notification level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: CASRN, Chemical 

Abstract Service Registry Number; LT-MDL, long-term method detection limit; SRL, study reporting level; D, detected in groundwater samples (table 7); na, 

not available; μg/L, micrograms per liter; —, not detected; KLAM, Klamath Mountains study unit]

Constituent USGS parameter 

code CASRN LT-MDL or SRL 

(μg/L) Benchmark type Benchmark level 

(μg/L) Detection

Aluminum 01106 7429-90-5 1

 1.6 MCL-CA 1,000 D

Antimony 01095 7440-36-0 0.054 MCL-US 6 D

Arsenic 01000 7440-38-2 0.044 MCL-US 10 D

Barium 01005 7440-39-3 1

 0.36 MCL-CA 1,000 D

Beryllium 01010 7440-41-7 0.012 MCL-US 4 D

Boron 01020 7440-42-8 2.8 NL-CA 1,000 D

Cadmium 01025 7440-43-9 0.02 MCL-US 5 D

Chromium 01030 7440-47-3 1

 0.42 MCL-CA 50 D

Cobalt 01035 7440-48-4 2

 0.23 na na D

Copper 01040 7440-50-8 1

 1.7 AL-US 1,300 D

Iron 01046 7439-89-6 1

 6 SMCL-CA 300 D

Lead 01049 7439-92-1 1

 0.65 AL-US 15 D

Lithium 01130 7439-93-2 0.44 na na D

Manganese 01056 7439-96-5 2

 0.36 SMCL-CA 50 D

Mercury 71890 7439-97-6 0.005 MCL-US 2 —

Molybdenum 01060 7439-98-7 0.028 HAL-US 40 D

Nickel 01065 7440-02-0 1

 0.36 MCL-CA 100 D

Selenium 01145 7782-49-2 0.040 MCL-US 50 D

Silver 01075 7440-22-4 0.005 SMCL-CA 100 D

Strontium 01080 7440-24-6 0.40 HAL-US 4,000 D

Thallium 01057 7440-28-0 0.020 MCL-US 2 D

Tungsten 01155 7440-33-7 1

 0.11 na na D

Vanadium 01085 7440-62-2 0.16 NL-CA 50 D

Zinc 01090 7440-66-6 1

 4.8 SMCL-CA3 5,000 D

1

 The SRL was defined by Olsen and others (2010).

2

 The SRL was defined based on the highest concentration detected in the KLAM field blank samples.

3

 Zinc also has a HAL-US benchmark of 2,000 μg/L.
Table 3E. Nutrients, comparative benchmarks, and reporting information for the U.S. Geological Survey (USGS) National Water Quality Laboratory (N[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. LT-MDL, benchmark type, and benchmark level as of October 1, 2010. Benccontaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCLU.S. Environmental Protection Agency (USEPA) lifetime health advisory level; MCL-US, USEPA maximum contaminant level. Other abbreviations: CASRN, Chemical Abstr

LT-MDL, long-term method detection limit; D, detected in groundwater samples (table 8); na, not available; mg/L, milligrams per liter]

Constituent USGS parameter code CASRN LT-MDL (mg/L) Benchmark type Benchma

(mg/

Ammonia (as nitrogen) 00608 7664-41-7 0.01 HAL-US 1 24.7 

Nitrite (as nitrogen) 00613 14797-65-0 0.001 MCL-US 1 

Nitrate plus nitrite (as nitrogen) 00631 na 0.02 MCL-US 10 

Total nitrogen (ammonia + nitrite + nitrate + organic nitrogen) 62854 17778-88-0 0.05 na na 

Phosphate, orthophosphate (as phosphorus) 00671 14265-44-2 0.006 na na 

1 The HAL-US is 30 mg/L “as ammonia.” To facilitate comparison to the analytical results, we have converted and reported this HAL-US as 24.7 mg/L “as nitrogen.”
36 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Table 3F. Major and minor ions, silica, total dissolved solids (TDS), and alkalinity, comparative benchmarks, and reporting information 

for the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) Schedule 1948.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. LT-MDL, benchmark type, and benchmark level as of 

October 1, 2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and 

as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. MCL-CA, California Department of Public Health (CDPH) maximum 

contaminant level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: CASRN, Chemical Abstract Service Registry Number; 

LT-MDL, long-term method detection limit; D, detected in groundwater samples (table 9); na, not available; mg/L, milligrams per liter; SiO2, silicon dioxide; 

CaCO3, calcium carbonate]

Constituent 

(synonym or abbreviation)

USGS 

parameter code CASRN LT-MDL 

(mg/L) Benchmark type Benchmark level 

(mg/L) Detection

Bromide 71870 24959-67-9 0.02 na na D

Calcium 00915 7440-70-2 0.044 na na D

Chloride 00940 16887-00-6 0.12 SMCL-CA 1

 250 (500) D

Fluoride 00950 16984-48-8 0.08 MCL-CA 2 D

Iodide 71865 7553-56-2 0.002 na na D

Magnesium 00925 7439-95-4 0.016 na na D

Potassium 00935 7440-09-7 0.064 na na D

Sodium 00930 7440-23-5 0.10 na na D

Sulfate 00945 14808-79-8 0.18 SMCL-CA 1

 250 (500) D

Silica (as SiO2

) 00955 7631-86-9 0.058 na na D

Total dissolved solids (TDS) 70300 na 10 SMCL-CA 1

 500 (1,000) D

Laboratory alkalinity (as CaCO3

) 2 29801 na 1 na na D

1

 The SMCL-CA for chloride, sulfate, and TDS have recommended and upper benchmark values. The upper benchmark value is shown in parentheses.

2

 Laboratory alkalinity results are presented in table 4.

Table 3G. Arsenic and iron species, comparison benchmarks, and reporting information for the U.S. Geological Survey (USGS)

National Research Laboratory (NRP) Trace Metal Laboratory (TML), Boulder, Colorado, analyses.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. MDL, benchmark type, and benchmark level as of October 1, 

2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when 

the MCL-CA is lower than the MCL-US or no MCL-US exists. MCL-US, U.S. Environmental Protection Agency maximum contaminant level; SMCL-CA, 

California Department of Public Health secondary maximum contaminant level. Other abbreviations: CASRN, Chemical Abstract Service Registry Number; 

MDL, method detection limit; na, not available; μg/L, micrograms per liter; D, detected in groundwater samples (table 10); —, not detected]

Constituent USGS 

parameter code CASRN MDL 

(μg/L)

Benchmark 

type

Benchmark level 

(μg/L) Detection

Arsenic (total) 99033 7440-38-2 0.5 MCL-US 10 D

Arsenic-III 99034 22569-72-8 1 na na —

Iron (total) 01046 7439-89-6 2 SMCL-CA 300 D

Iron-II 01047 7439-89-6 2 na na D
Table 3H. Dissolved noble gases, isotopic tracers, and uranium and other radioactive constituents, comparison benchmarks and reporting informati[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Laboratory entity codes in the USGS National Water Information System (Nthan the USGS National Water Quality Laboratory (NWQL) are given in parentheses after the laboratory names. Benchmark type and benchmark value as of October 1, 2010. Bcontaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCLU.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Health maximum contaminant level. Elements: H, hydrogen; OC, carbon. Reporting units: μg/L, micrograms per liter; mg/L, milligrams per liter; pCi/L, picocuries per liter; cm3 STP/g, cubic centimeters of gas at standard temperature and 

Other abbreviations: USGS, U.S. Geological Survey; CASRN, Chemical Abstract Service Registry Number; %, percent; na, not available; pmc, percent modern carbon; D, det(tables 11, 12, and 13); ssLC, sample-specific critical level; NRP, National Research Program]

Constituent USGS parameter code CASRN Method uncertainty Reporting units Benchmark type Benc

Dissolved noble gases 1

Argon 85563 7440-37-1 2% cm3 STP/g na 

Helium-4 85561 7440-59-7 2% cm3 STP/g na Krypton 85565 7439-90-9 2% cm3 STP/g na Neon 61046 7440-01-09 2% cm3 STP/g na Xenon 85567 7440-63-3 2% cm3 STP/g na Isotopic tracersHelium-3 / Helium-4 1 61040 na / 7440-59-7 0.75% atom ratio na 

δ2H in water 2 82082 na 2 per mil na δ18O in water 2 82085 na 0.20 per mil na Strontium isotope ratio in water (87Sr/86Sr) 3 75978 na 0.00005 atom ratio na δ13C in dissolved inorganic carbon 4 82081 na 0.05 per mil na Uranium and other radioactive constituentsUranium 6 22703 7440-61-1 LT-MDL μg/L MCL-US C-14 4 49933 14762-75-5 0.0015 pmc na Tritium 1 07000 10028-17-8 ssLC pCi/L MCL-CA 

Tritium 5 07000 10028-17-8 ssLC pCi/L MCL-CA Radon-222 6 82303 14859-67-7 ssLC pCi/L MCL-US (Proposed) 

Gross alpha radioactivity, 72-hour and 30-day counts 7 62636, 62639 12587-46-1 ssLC pCi/L MCL-US 

Gross beta radioactivity, 72-hour and 30-day counts 7 62642, 62645 12587-47-2 ssLC pCi/L MCL-CA 

1 Lawrence Livermore National Laboratory, Livermore, California (CA-LLNL).2 USGS Stable Isotope Laboratory, Reston, Virginia (USGSSIVA).3 USGS-NRP Metals Isotope Research Laboratory, Menlo Park, California (USGSMICA).4 Woods Hole Oceanographic Institution, National Ocean Sciences Accelerator Mass Spectrometry Facility [NOMAS], Woods Hole, Massachusetts (MA-WHAMS).5 USGS Stable Isotope and Tritium Laboratory [SITL], Menlo Park, California (USGSH3CA).6 USGS NWQL Denver, Colorado.7 Eberline Analytical Services, Richmond, California (CA-EBERL).8 The MCL-US benchmark for gross alpha activity applies to adjusted gross alpha, which is equal to measured gross alpha activity minus uranium activity.
38 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Table 3I. Microbial indicators, comparison benchmarks, and reporting information for the IDEXX Colilert® field test kit analyses.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. MDL, benchmark type, and benchmark level as of October 1, 

2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA 

when the MCL-CA is lower than the MCL-US or no MCL-US exists. TT-US, U.S. Environmental Protection Agency (USEPA) treatment technique—a 

required process intended to reduce the level of contamination in drinking water; MCL-US, USEPA maximum contaminant level. Other abbreviations: USGS, 

U.S. Geological Survey; MDL, method detection limit; %, percent; D, detected in groundwater samples (table 14)]

Constituent USGS 

parameter code

Primary 

source MDL Benchmark 

type

Benchmark 

value Detection

Total coliform (including fecal 

coliform and Escherichia coli

[E. coli])

99595 Sewage and animal 

waste indicator

presence / 

absence

MCL-US 5% of samples positive 

per month

D

E. coli 99596 Sewage and animal 

waste indicator

presence / 

absence

TT-US No fecal coliforms are 

allowed

D
Table 4. Water-quality indicators in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA

October to December 2010.

[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. GAMA site identification number: KLAM, Klaunit; KLAM-U, Klamath Mountains study unit understanding site. Benchmark type, benchmark level, and RL as of October 1, 2010. Benchmark type: SMCL-US, U.S. Envirosecondary maximum contaminant level; SMCL-CA, California Department of Public Health secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geologmg/L, milligrams per liter; nc, not collected; na, not available; RL, reporting level or range; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium c

a higher degree of uncertainty; *, concentration greater than the benchmark level; **, concentration greater than the upper benchmark level; —, not detected]

GAMA site 

identification 

number

Dissolved 

oxygen, field 

(mg/L) 

(00300) 

Water 

temperature, 

field 

(°C) 

(00010)

pH, field 

(standard 

units) 

(00400)

pH, 

laboratory 

(standard 

units) 

(00403)

Specific 

conductance, field 

(μS/cm at 25 °C) 

(00095)

Specific 

conductance, 

laboratory 

(μS/cm at 25 °C) 

(90095)

Alkalinity, 

field 

(mg/L as 

CaCO3) 

(29802)

Alkalinity, 

laboratory 

(mg/L as 

CaCO3) 

(29801)

Bicarbonate, 

field 

(mg/L) 

(63786)

Bicarbonate

laboratory 2

(mg/L)

Benchmark type

na na SMCL-US SMCL-US SMCL-CA SMCL-CA na na na na 

Benchmark level

na na <6.5 or >8.5 <6.5 or >8.5 1 900 (1,600) 1 900 (1,600) na na na na 

[RL] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [1] [1] [1] [1] 

KLAM grid sites (38 sites sampled)KLAM-01 10.1 13.0 8.2 8.3 190 194 nc 104 nc 124 

KLAM-02 10.6 9.0 *6.1 7.0 167 172 69.8 78.0 85.0 95.1 

KLAM-03 3.2 15.0 6.9 7.2 391 400 167 183 204 223 

KLAM-04 7.9 13.0 *6.3 E7.0 87 E91 nc 43.9 nc 53.5 

KLAM-05 8.7 11.0 7.2 7.7 372 374 nc 197 nc 239 

KLAM-06 0.5 16.5 8.3 8.3 **1,690 **1,690 nc 140 nc 168 

KLAM-07 8.4 13.0 7.1 7.3 338 343 nc 189 nc 230 

KLAM-08 0.9 11.5 7.3 7.5 295 292 nc 130 nc 158 

KLAM-09 2.9 12.5 6.5 7.0 269 271 nc 121 nc 147 

KLAM-10 nc 13.0 *6.0 E7.4 62 E62 nc 32.8 nc 39.9 

KLAM-11 9.4 13.0 6.9 7.4 207 207 nc 112 nc 136 

KLAM-12 7.5 10.5 6.6 7.4 144 145 70.4 76.7 85.7 93.3 

KLAM-13 7.8 12.5 6.7 7.0 245 247 114 129 139 157 

KLAM-14 6.9 13.0 7.2 7.1 459 463 nc 246 nc 300 

KLAM-15 9.3 11.0 6.8 7.2 337 344 nc 181 nc 220 
GAMA site identification number Dissolved oxygen, field (mg/L) (00300) Water temperature, field (°C) (00010) pH, field (standard units) (00400) pH, laboratory (standard units) (00403) Specific conductance, field (μS/cm at 25 °C) (00095) Specific conductance, laboratory (μS/cm at 25 °C) (90095) Alkalinity, field (mg/L as CaCO3) (29802) Alkalinity, laboratory (mg/L as CaCO3) (29801) Bicarbonate, field (mg/L) (63786) Bicarbonate

laboratory 2 (mg/L) 

Benchmark type na na SMCL-US SMCL-US SMCL-CA SMCL-CA na na na na 

Benchmark level na na <6.5 or >8.5 <6.5 or >8.5 1 900 (1,600) 1 900 (1,600) na na na na 

[RL] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [1] [1] [1] [1] 

KLAM grid sites (38 sites sampled)—Continued KLAM-16 4.5 14.0 *5.9 *E6.2 77 E80 nc 38.2 nc 46.6 

KLAM-17 2.2 12.0 *6.2 6.5 220 227 nc 115 nc 140 

KLAM-18 6.1 9.5 *6.1 E6.5 86 E90 nc 48.0 nc 58.6 

KLAM-19 2.0 14.0 7.2 7.5 195 197 98.1 103 119 125 

KLAM-20 7.5 10.0 7.6 7.8 226 230 nc 131 nc 159 

KLAM-21 7.2 12.0 7.2 7.3 326 326 172 184 209 224 

KLAM-22 10.7 13.5 7.0 7.2 207 210 nc 100 nc 122 

KLAM-23 2.5 15.0 7.4 8.4 289 292 nc 130 nc 155 

KLAM-24 0.4 11.0 7.5 7.5 506 526 nc 221 nc 269 

KLAM-25 2.4 16.5 7.0 7.0 401 385 167 174 203 212 

KLAM-26 1.4 17.0 6.8 7.0 296 303 124 134 151 163 

KLAM-27 6.1 15.0 *6.2 6.5 261 259 nc 75.5 nc 92.1 

KLAM-28 3.4 11.5 6.5 6.9 137 140 nc 62.0 nc 75.6 

KLAM-29 11.8 7.5 6.6 7.0 114 115 nc 56.5 nc 68.9 

KLAM-30 <0.2 12.0 6.8 7.1 340 342 nc 151 nc 184 

Table 4. Water-quality indicators in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMAOctober to December 2010.—Continued [The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. GAMA site identification number: KLAM, Klaunit; KLAM-U, Klamath Mountains study unit understanding site. Benchmark type, benchmark level, and RL as of October 1, 2010. Benchmark type: SMCL-US, U.S. Envirosecondary maximum contaminant level; SMCL-CA, California Department of Public Health secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geologmg/L, milligrams per liter; nc, not collected; na, not available; RL, reporting level or range; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium c

a higher degree of uncertainty; *, concentration greater than the benchmark level; **, concentration greater than the upper benchmark level; —, not detected]
GAMA site 

identification 

number

Dissolved 

oxygen, field 

(mg/L) 

(00300) 

Water 

temperature, 

field 

(°C) 

(00010)

pH, field 

(standard 

units) 

(00400)

pH, 

laboratory 

(standard 

units) 

(00403)

Specific 

conductance, field 

(μS/cm at 25 °C) 

(00095)

Specific 

conductance, 

laboratory 

(μS/cm at 25 °C) 

(90095)

Alkalinity, 

field 

(mg/L as 

CaCO3) 

(29802)

Alkalinity, 

laboratory 

(mg/L as 

CaCO3) 

(29801)

Bicarbonate, 

field 

(mg/L) 

(63786)

Bicarbonate

laboratory 2

(mg/L)

Benchmark type

na na SMCL-US SMCL-US SMCL-CA SMCL-CA na na na na 

Benchmark level

na na <6.5 or >8.5 <6.5 or >8.5 1 900 (1,600) 1 900 (1,600) na na na na 

[RL] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [1] [1] [1] [1] 

KLAM grid sites (38 sites sampled)—ContinuedKLAM-31 2.6 10.0 *9.4 *9.3 555 572 nc 379 nc 389 

KLAM-32 4.2 13.5 6.9 7.1 225 231 108 121 132 147 

KLAM-33 0.9 14.0 7.6 7.7 186 189 66.3 80.4 80.4 97.6 

KLAM-34 5.6 16.0 7.3 7.6 460 464 nc 177 nc 215 

KLAM-35 4.1 14.0 6.7 7.1 225 227 nc 119 nc 145 

KLAM-36 7.0 11.0 6.6 7.0 142 143 nc 77.5 nc 94.5 

KLAM-37 2.3 14.5 *6.1 *6.3 192 195 nc 57.7 nc 70.4 

KLAM-38 7.3 10.0 6.9 7.2 180 184 nc 80.1 nc 97.6 

KLAM understanding siteKLAM-U-01 7.4 13.0 7.2 7.5 435 438 194 197 236 240 

1 The SMCL-CA for specific conductance has recommended and upper benchmark values. The upper value is shown in parentheses.2 Bicarbonate and carbonate concentrations were calculated from the laboratory alkalinity and pH values by using the advanced speciation method (http://or.water.usgs.gov/alk

pK2 = 10.33, and pKW = 14.

Table 4. Water-quality indicators in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMAOctober to December 2010.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. GAMA site identification number: KLAM, Klaunit; KLAM-U, Klamath Mountains study unit understanding site. Benchmark type, benchmark level, and RL as of October 1, 2010. Benchmark type: SMCL-US, U.S. Envirosecondary maximum contaminant level; SMCL-CA, California Department of Public Health secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geologmg/L, milligrams per liter; nc, not collected; na, not available; RL, reporting level or range; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium c

a higher degree of uncertainty; *, concentration greater than the benchmark level; **, concentration greater than the upper benchmark level; —, not detected]
Table 5. Volatile organic compounds (VOCs) detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring an

study unit, California, October to December 2010. [The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were analyzed, but onl

listed. Detected constituents are grouped by primary use or source and listed in order of decreasing detection frequency in the 38 grid sites. All constituents are listed in table 3A

number: KLAM, Klamath Mountains study unit; KLAM-U, Klamath Mountains study unit understanding site. Benchmark type, benchmark level, and LRL as of October 1, 20

contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCLU.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; NL-CA, CDPH n

abbreviations: USGS, U.S. Geological Survey; ≤, less than or equal to; LRL, laboratory reporting level; SRL, study reporting level; μg/L, micrograms per liter; na, not availabl

Primary use or source Trihalomethanes Solvents Hydrocarbons Natural Gasoline oxygenat

GAMA site identification number Chloroform (Trichloro- methane) (μg/L) (32106) Bromodi- chloro- methane (μg/L) (32101) Dibromo- chloro- methane (μg/L) (32105) Methyl ethyl ketone (2-butanone, MEK) (μg/L) (81595) Perchloroethene (PCE, Tetrachloro- ethene) (μg/L) (34475) Trichloro- ethene (TCE) (μg/L) (39180) Toluene (μg/L) (34010) Styrene (μg/L) (77128) Carbon disulfide (μg/L) (77041) Methyl te

butyl ethe

(MTBE) (μg/L) (78032) Benchmark type MCL-US MCL-US MCL-US HAL-US MCL-US MCL-US MCL-CA MCL-US NL-CA MCL-CA Benchmark level 2 80 2 80 2 80 4,000 5 5 150 100 160 13 [LRL or SRL] [0.03] [0.034] [0.12] [1.6] [0.026] [0.018] [0.69] 1 [0.03] [0.03] [0.1] KLAM grid sites (38 sites sampled) KLAM-07 0.19 — — — — — — — — — 

KLAM-08 0.03 — — — — — — — — — 

KLAM-09 0.03 — — — — — — — — — 

KLAM-12 — — — 1.0 — — — — — — 

KLAM-17 — — — — — — — — — 0.76 

KLAM-18 0.02 — — — — — — — — — 

KLAM-22 0.01 — — — — — — — — — 

KLAM-23 0.08 — — — — — — — — — 

KLAM-25 — — — — — — ≤0.01 0.12 — — 

KLAM-26 0.03 — — — — — — — — — 

KLAM-27 0.02 — — — — — — — — — 

KLAM-28 0.02 — — 1.7 — — — — — — 

KLAM-30 — — — — — — — — 0.10 — 

KLAM-31 0.12 — — — — — — — — — 

KLAM-34 0.66 0.082 — — 0.012 0.026 — — — — 
Primary use or 

source

Trihalomethanes Solvents Hydrocarbons Natural Gasoline oxygenat

GAMA site 

identification 

number

Chloroform 

(Trichloromethane) 

(μg/L) 

(32106)

Bromodichloromethane 

(μg/L) 

(32101)

Dibromochloromethane 

(μg/L) 

(32105)

Methyl ethyl 

ketone 

(2-butanone, MEK) 

(μg/L) 

(81595)

Perchloroethene 

(PCE, Tetrachloroethene) 

(μg/L) 

(34475)

Trichloroethene 

(TCE) 

(μg/L) 

(39180)

Toluene 

(μg/L) 

(34010)

Styrene 

(μg/L) 

(77128)

Carbon 

disulfide 

(μg/L) 

(77041)

Methyl te

butyl ethe

(MTBE) 

(μg/L) 

(78032)

Benchmark type MCL-US MCL-US MCL-US HAL-US MCL-US MCL-US MCL-CA MCL-US NL-CA MCL-CA

Benchmark level 2 80 2 80 2 80 4,000 5 5 150 100 160 13

[LRL or SRL] [0.03] [0.034] [0.12] [1.6] [0.026] [0.018] [0.69] 1 [0.03] [0.03] [0.1]

KLAM grid sites (38 sites sampled)—ContinuedKLAM-37 2.3 0.534 0.17 — — — — — — — 

Number of sites 

with detections

12 2 1 2 1 1 0 1 1 1 

Detection frequency 

(percent)

31.6 5.3 2.6 5.3 2.6 2.6 0 2.6 2.6 2.6 

Total detections 

(number)

— — — — — — — — — — 

KLAM understanding site 3

KLAM-U-01 0.02 — — — — — 1.0 — — — 

1 The SRLs for toluene, tetrahydrofuran, and 1,2,4-trimethylbenzene were defined by Fram and others (2012). All detections of tetrahydrofuran (KLAM-12: 6 μg/L; KLAM-2

1,2,4-trimethylbenzene (KLAM-02: 0.02 μg/L; KLAM-04: 0.02 μg/L; KLAM-05: 0.03 μg/L; KLAM-06: 0.06 μg/L; KLAM-07: 0.04 μg/L; KLAM-08: 0.11 μg/L; KLAM-09: 0

KLAM-12: 0.06 μg/L; KLAM-13: 0.26 μg/L; KLAM-14: 0.38 μg/L; KLAM-15: 0.30 μg/L; KLAM-16: 0.08 μg/L; KLAM-18: 0.09 μg/L; KLAM-19: 0.10 μg/L; KLAM-21: 0.0KLAM-23: 0.02 μg/L; KLAM-24: 0.04 μg/L; KLAM-25: 0.05 μg/L; KLAM-26: 0.03 μg/L; KLAM-27: 0.04 μg/L; KLAM-28: 0.13 μg/L; KLAM-29: 0.03 μg/L; KLAM-30: 0.0KLAM-32: 0.02 μg/L; KLAM-33: 0.02 μg/L; KLAM-34: 0.05 μg/L; KLAM-35: 0.04 μg/L; KLAM-38: 0.06 μg/L) have been reclassified as non-detections and are not presenteappendix section titled “Quality-Assurance and Quality-Control Methods and Results” for more information.

2 The MCL-US benchmark for trihalomethanes is the sum of chloroform, bromoform, bromodichloromethane, and dibromochloromethane.3 The understanding site was not included in statistical calculations.

Table 5. Volatile organic compounds (VOCs) detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring anstudy unit, California, October to December 2010.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were analyzed, but onllisted. Detected constituents are grouped by primary use or source and listed in order of decreasing detection frequency in the 38 grid sites. All constituents are listed in table 3A

number: KLAM, Klamath Mountains study unit; KLAM-U, Klamath Mountains study unit understanding site. Benchmark type, benchmark level, and LRL as of October 1, 20

contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCLU.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; NL-CA, CDPH n

abbreviations: USGS, U.S. Geological Survey; ≤, less than or equal to; LRL, laboratory reporting level; SRL, study reporting level; μg/L, micrograms per liter; na, not availabl
44 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Table 6. Pesticides and pesticide degradates detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient 

Monitoring and Assessment (GAMA) study unit, California, October to December 2010.

[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were 

analyzed, but only samples with detections are listed. Detected constituents are grouped by primary use or source and then listed in order of decreasing detection 

frequency in the 38 grid sites. All constituents are listed in table 3B. GAMA site identification number: KLAM, Klamath Mountains study unit. Benchmark 

type, benchmark level, and LRL as of October 1, 2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US 

and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. MCL-US, U.S. Environmental Protection 

Agency (USEPA) maximum contaminant level; HAL-US, USEPA lifetime health advisory level; MCL-CA; California Department of Public Health maximum 

contaminant level. Other abbreviations: USGS, U.S. Geological Survey; E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; 

μg/L, micrograms per liter; na, not available; —, not detected]

Primary use or source Herbicide degradate Herbicide

Pesticide 

detections 

per site

Pesticide 

detection 

summary

GAMA site 

identification 

number

Deethylatrazine 

(2-Chloro-4-isopropylamino-6-

amino-s-triazine) 

(μg/L) 

(04040)

Atrazine 

(μg/L) 

(39632)

Simazine 

(μg/L) 

(04035)

Hexazinone 

(μg/L) 

(04025)

Benchmark type na MCL-CA MCL-US HAL-US

Benchmark level na 1 4 400

[LRL] [0.014] [0.007] [0.006] [0.008]

KLAM grid sites (38 sites sampled)

KLAM-03 — — 0.011 — 1 —

KLAM-13 — — 0.007 — 1 —

KLAM-16 E0.007 — — — 1 —

KLAM-26 E0.042 — — — 1 —

KLAM-28 E0.007 0.006 — — 2 —

KLAM-29 E0.008 — — 0.065 2 —

KLAM-32 E0.010 — — — 1 —

KLAM-34 E0.009 0.009 — — 2 —

Number of sites with detections 6 2 2 1 — 8

Detection frequency (percent) 15.8 5.3 5.3 2.6 — 21

Total detections (number) — — — — — 11
Table 7. Trace elements detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAM

October to December 2010.

[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were analyzed, with thwas sampled for at KLAM-19 per owner’s request. Information about the constituents given in table 3D. GAMA site identification number: KLAM, Klamath Mountains study Mountains study unit understanding site. Benchmark type, benchmark level, and LT-MDL as of March 1, 2010. Benchmark type: Maximum contaminant level benchmarks are MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. AL-US, U.S. Environmental Protection Agency (USUSEPA lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant levellevel; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; LT-MDL, long-term method detection limit; SRL, studmicrograms per liter; na, not available; —, not detected; ≤, less than or equal to; *, concentration greater than the benchmark level; nc, not collected]

GAMA site 

identification 

number

Aluminum 

(μg/L) 

(01106) 

Antimony 

(μg/L) 

(01095) 

Arsenic 

(μg/L) 

(01000) 

Barium 

(μg/L) 

(01005) 

Beryllium 

(μg/L) 

(01010)

Boron 

(μg/L) 

(01020) 

Cadmium 

(μg/L) 

(01025) 

Chromium 

(μg/L) 

(01030) 

Cobalt 

(μg/L) 

(01035) 

Copper 

(μg/L) 

(01040) 

Benchmark type MCL-CA MCL-US MCL-US MCL-CA MCL-US NL-CA MCL-US MCL-CA na AL-US Benchmark level 1,000 6 10 1,000 4 1,000 5 50 na 1,300 [LT-MDL or SRL] [1.7] [0.027] [0.022] [0.36] 1 [0.006] [3] [0.016] [0.42] 1 [0.23] 2 [1.7] 1 

KLAM grid sites (38 sites sampled)KLAM-01 — — — 0.47 — — — 1.5 ≤0.02 ≤1.3 

KLAM-02 2.7 — 0.15 51.6 — — — 0.43 ≤0.04 8.2 

KLAM-03 4.6 0.028 0.19 15.4 — 26 — ≤0.25 ≤0.05 ≤0.99 

KLAM-04 — — — 70.6 — — 0.020 ≤0.15 ≤0.03 26.0 

KLAM-05 — 0.051 0.52 30.2 — 7 — 0.49 ≤0.04 3.6 

KLAM-06 — — 0.17 39.2 0.052 *2,230 — — — — 

KLAM-07 7.3 0.097 1.30 1.5 — 94 — 6.3 ≤0.04 4.0 

KLAM-08 — 0.229 0.43 82.6 — 29 — — ≤0.06 — 

KLAM-09 — 0.055 0.08 65.8 — 11 — ≤0.17 ≤0.10 — KLAM-10 2.7 — 0.12 9.2 — 3 0.018 0.73 ≤0.18 3.2 

KLAM-11 2.8 0.061 0.36 1.5 — 44 — 0.43 — ≤0.80 

KLAM-12 24.7 — 0.13 1.0 — 3 — ≤0.08 — ≤1.3 

KLAM-13 — — 0.08 7.3 — 37 — ≤0.40 ≤0.02 2.8 

KLAM-14 — — 0.27 51.4 — 93 — ≤0.36 ≤0.02 ≤1.6 KLAM-15 — 0.028 0.10 9.6 — 20 — ≤0.39 ≤0.04 4.1 KLAM-16 2.2 — 0.06 81.1 — 8 0.053 0.97 — — 

KLAM-17 1.9 — 0.29 12.3 — 13 — ≤0.18 ≤0.04 ≤1.6 

KLAM-18 1.9 — — ≤0.15 — — — 1.0 ≤0.07 ≤1.0 KLAM-19 — 0.057 4.2 50.7 — 32 — — ≤0.03 ≤1.3 KLAM-20 2.1 — 0.05 8.9 — — — 6.9 — — 
GAMA site identification number Aluminum (μg/L) (01106) Antimony (μg/L) (01095) Arsenic (μg/L) (01000) Barium (μg/L) (01005) Beryllium (μg/L) (01010) Boron (μg/L) (01020) Cadmium (μg/L) (01025) Chromium (μg/L) (01030) Cobalt (μg/L) (01035) Copper (μg/L) (01040) 

Benchmark type MCL-CA MCL-US MCL-US MCL-CA MCL-US NL-CA MCL-US MCL-CA na AL-US Benchmark level 1,000 6 10 1,000 4 1,000 5 50 na 1,300 [LT-MDL or SRL] [1.7] [0.027] [0.022] [0.36] 1 [0.006] [3] [0.016] [0.42] 1 [0.23] 2 [1.7] 1 

KLAM grid sites (38 sites sampled)—Continued KLAM-21 — — 0.65 16.1 — 4 — 0.79 — ≤1.7 

KLAM-22 1.9 0.077 0.37 20.4 — 41 — 2.0 ≤0.06 2.3 

KLAM-23 15.7 — 0.88 6.5 — — — ≤0.23 ≤0.05 ≤1.2 

KLAM-24 2.0 — 0.12 11.1 — 10 — — ≤0.08 — 

KLAM-25 3.0 0.193 0.43 38.4 — 114 — ≤0.24 ≤0.11 — 

KLAM-26 3.9 — 0.07 1.5 — 64 — ≤0.13 ≤0.03 ≤0.67 

KLAM-27 4.4 0.276 0.08 35.5 — 17 — — 0.72 1.9 

KLAM-28 — — 0.16 8.8 — 4 — ≤0.07 — — 

KLAM-29 8.2 — 0.29 2.9 0.009 17 — ≤0.42 — ≤1.2 KLAM-30 1.8 — 0.06 18.9 0.030 590 — — ≤0.02 — KLAM-31 — 0.032 0.05 0.84 — 177 — 1.4 ≤0.04 — 

KLAM-32 — — 0.12 45.9 — 13 — ≤0.23 ≤0.02 ≤1.6 

KLAM-33 12.0 0.049 0.89 244 0.008 381 — — — — 

KLAM-34 3.5 0.055 0.26 19.0 — 13 0.019 ≤0.41 ≤0.07 ≤0.79 

KLAM-35 2.9 0.036 0.25 0.71 — — 0.076 ≤0.07 ≤0.02 8.9 KLAM-36 3.1 0.036 0.13 3.3 — 13 — 1.2 ≤0.10 ≤1.5 

KLAM-37 9.7 — 0.16 24.6 — 49 0.027 0.76 ≤0.15 2.8 

KLAM-38 8.9 0.031 0.13 1.9 — — — ≤0.10 — 3.6 

Table 7. Trace elements detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMOctober to December 2010.—Continued [The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were analyzed, with thwas sampled for at KLAM-19 per owner’s request. Information about the constituents given in table 3D. GAMA site identification number: KLAM, Klamath Mountains study Mountains study unit understanding site. Benchmark type, benchmark level, and LT-MDL as of March 1, 2010. Benchmark type: Maximum contaminant level benchmarks are MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. AL-US, U.S. Environmental Protection Agency (USUSEPA lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant levellevel; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; LT-MDL, long-term method detection limit; SRL, studmicrograms per liter; na, not available; —, not detected; ≤, less than or equal to; *, concentration greater than the benchmark level; nc, not collected]
GAMA site 

identification 

number

Aluminum 

(μg/L) 

(01106) 

Antimony 

(μg/L) 

(01095) 

Arsenic 

(μg/L) 

(01000) 

Barium 

(μg/L) 

(01005) 

Beryllium 

(μg/L) 

(01010)

Boron 

(μg/L) 

(01020) 

Cadmium 

(μg/L) 

(01025) 

Chromium 

(μg/L) 

(01030) 

Cobalt 

(μg/L) 

(01035) 

Copper 

(μg/L) 

(01040) 

Benchmark type MCL-CA MCL-US MCL-US MCL-CA MCL-US NL-CA MCL-US MCL-CA na AL-US Benchmark level 1,000 6 10 1,000 4 1,000 5 50 na 1,300 [LT-MDL or SRL] [1.7] [0.027] [0.022] [0.36] 1 [0.006] [3] [0.016] [0.42] 1 [0.23] 2 [1.7] 1 

KLAM understanding siteKLAM-U-01 — 0.08 0.98 29.1 — 6 — 0.45 ≤0.06 ≤0.87 

GAMA site 

identification 

number

Lithium 

(μg/L) 

(01130) 

Manganese 

(μg/L) 

(01056) 

Mercury 

(μg/L) 

(71890) 

Molybdenum 

(μg/L) 

(01060) 

Nickel 

(μg/L) 

(01065) 

Selenium 

(μg/L) 

(01145) 

Silver 

(μg/L) 

(01075) 

Strontium 

(μg/L) 

(01080)

Thallium 

(μg/L) 

(01057) 

Tungsten 

(μg/L) 

(01155)

Benchmark type na SMCL-CA MCL-US HAL-US MCL-CA MCL-US SMCL-CA HAL-US MCL-US na 

Benchmark level na 50 2 40 100 50 100 4,000 2 na 

[LT-MDL or SRL] [0.22] [0.36] 2 [0.005] [0.014] [0.36] 1 [0.03] [0.005] [0.2] [0.01] [0.11] 1 

KLAM grid sites (38 sites sampled)KLAM-01 — — nc 0.040 2.3 0.04 — 3.24 — — 

KLAM-02 2.43 2.4 nc 0.224 24.4 0.38 — 40.7 — — KLAM-03 0.69 6.6 nc 0.781 0.43 0.73 — 494 — — 

KLAM-04 1.84 1.3 nc — 0.43 0.04 — 55.8 — — 

KLAM-05 — 0.57 nc 0.479 ≤0.17 0.22 — 197 — — 

KLAM-06 138 25.2 nc 0.279 — — — 806 — ≤0.07 KLAM-07 — ≤0.14 nc 0.243 ≤0.34 0.09 — 48.4 — 0.56 

KLAM-08 7.55 21.3 nc 1.96 0.61 0.15 — 1,600 — ≤0.02 

KLAM-09 3.64 30.8 nc 0.889 4.4 0.74 — 321 — ≤0.01 

KLAM-10 — — nc 0.117 6.9 0.07 — 87.7 — — 

Table 7. Trace elements detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMOctober to December 2010.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were analyzed, with thwas sampled for at KLAM-19 per owner’s request. Information about the constituents given in table 3D. GAMA site identification number: KLAM, Klamath Mountains study Mountains study unit understanding site. Benchmark type, benchmark level, and LT-MDL as of March 1, 2010. Benchmark type: Maximum contaminant level benchmarks are MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. AL-US, U.S. Environmental Protection Agency (USUSEPA lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant levellevel; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; LT-MDL, long-term method detection limit; SRL, studmicrograms per liter; na, not available; —, not detected; ≤, less than or equal to; *, concentration greater than the benchmark level; nc, not collected]
GAMA site identification number Lithium (μg/L) (01130) Manganese (μg/L) (01056) Mercury (μg/L) (71890) Molybdenum (μg/L) (01060) Nickel (μg/L) (01065) Selenium (μg/L) (01145) Silver (μg/L) (01075) Strontium (μg/L) (01080) Thallium (μg/L) (01057) Tungsten (μg/L) (01155) 

Benchmark type na SMCL-CA MCL-US HAL-US MCL-CA MCL-US SMCL-CA HAL-US MCL-US na 

Benchmark level na 50 2 40 100 50 100 4,000 2 na 

[LT-MDL or SRL] [0.22] [0.36] 2 [0.005] [0.014] [0.36] 1 [0.03] [0.005] [0.2] [0.01] [0.11] 1 

KLAM grid sites (38 sites sampled)—Continued KLAM-11 — — nc 0.513 ≤0.33 0.28 — 94.0 — ≤0.01 

KLAM-12 0.79 ≤0.15 nc — ≤0.32 — — 17.0 — — KLAM-13 — 0.40 nc 0.304 1.7 0.06 — 45.4 — — 

KLAM-14 1.91 — nc 0.599 0.43 0.36 — 208 — ≤0.02 

KLAM-15 0.54 ≤0.21 nc 0.188 ≤0.25 0.21 — 240 — — KLAM-16 5.44 ≤0.22 nc 0.049 2.5 0.36 — 36.0 — — KLAM-17 17.8 ≤0.30 nc 0.555 0.45 0.05 — 125 — ≤0.01 KLAM-18 0.43 36.1 nc — 0.95 — — 27.8 — — 

KLAM-19 — 1.2 — 0.189 ≤0.26 0.09 0.012 26.2 0.01 — KLAM-20 0.44 — nc — 2.1 — — 55.7 — — 

KLAM-21 8.90 — nc 0.892 — 0.10 — 60.4 — ≤0.04 KLAM-22 0.63 5.2 nc 0.364 13.7 0.31 — 143 — — 

KLAM-23 10.6 1.7 nc 2.92 0.42 1.0 — 208 — 0.17 

KLAM-24 10.5 *146 nc 0.347 0.67 — — 303 — 0.13 KLAM-25 12.2 *121 nc 0.443 0.42 — — 198 — ≤0.08 

Table 7. Trace elements detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMto December 2010.—Continued [The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were analyzed, with thwas sampled for at KLAM-19 per owner’s request. Information about the constituents given in table 3D. GAMA site identification number: KLAM, Klamath Mountains study Mountains study unit understanding site. Benchmark type, benchmark level, and LT-MDL as of March 1, 2010. Benchmark type: Maximum contaminant level benchmarks are MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. AL-US, U.S. Environmental Protection Agency (USUSEPA lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant levellevel; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; LT-MDL, long-term method detection limit; SRL, studmicrograms per liter; na, not available; —, not detected; ≤, less than or equal to; *, concentration greater than the benchmark level; nc, not collected]
GAMA site 

identification 

number

Lithium 

(μg/L) 

(01130) 

Manganese 

(μg/L) 

(01056) 

Mercury 

(μg/L) 

(71890) 

Molybdenum 

(μg/L) 

(01060) 

Nickel 

(μg/L) 

(01065) 

Selenium 

(μg/L) 

(01145) 

Silver 

(μg/L) 

(01075) 

Strontium 

(μg/L) 

(01080)

Thallium 

(μg/L) 

(01057) 

Tungsten 

(μg/L) 

(01155)

Benchmark type na SMCL-CA MCL-US HAL-US MCL-CA MCL-US SMCL-CA HAL-US MCL-US na 

Benchmark level na 50 2 40 100 50 100 4,000 2 na 

[LT-MDL or SRL] [0.22] [0.36] 2 [0.005] [0.014] [0.36] 1 [0.03] [0.005] [0.2] [0.01] [0.11] 1 

KLAM grid sites (38 sites sampled)—ContinuedKLAM-26 3.12 0.94 nc 0.754 0.48 0.16 — 70.4 — ≤0.02 KLAM-27 10.1 *66.5 nc 0.101 0.57 — — 119 — ≤0.02 KLAM-28 0.32 1.4 nc 0.041 ≤0.14 0.08 — 39.8 — — 

KLAM-29 3.93 — nc 0.126 — — 0.005 68.3 — ≤0.02 

KLAM-30 13.0 *104 nc 0.941 5.6 — — 137 — 0.52 KLAM-31 4.67 31.9 nc 0.107 0.62 0.04 — 5.71 — 1.0 KLAM-32 0.33 1.8 nc 2.11 ≤0.31 0.22 — 57.3 — — KLAM-33 19.2 8.8 nc 1.10 — 0.50 0.006 364 — 0.16 

KLAM-34 1.07 4.2 nc 0.097 ≤0.28 0.54 — 79.6 — — 

KLAM-35 — — nc 0.164 ≤0.10 0.11 — 15.4 — 0.18 

KLAM-36 0.38 ≤0.36 nc 0.078 18.6 — — 16.5 — — 

KLAM-37 0.35 1.0 nc 0.066 9.2 0.09 0.005 78.6 — — 

KLAM-38 — ≤0.14 nc 0.101 ≤0.10 0.13 — 29.7 — — 

KLAM understanding siteKLAM-U-01 4.82 7.6 nc 1.11 0.61 0.89 — 274 — — 

1 The SRL was defined by Olsen and others (2010).2 The SRL was defined based on the highest concentration detected in KLAM field blank samples.

Table 7. Trace elements detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMto December 2010.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were analyzed, with thwas sampled for at KLAM-19 per owner’s request. Information about the constituents given in table 3D. GAMA site identification number: KLAM, Klamath Mountains study Mountains study unit understanding site. Benchmark type, benchmark level, and LT-MDL as of March 1, 2010. Benchmark type: Maximum contaminant level benchmarks are MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. AL-US, U.S. Environmental Protection Agency (USUSEPA lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant levellevel; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; LT-MDL, long-term method detection limit; SRL, studmicrograms per liter; na, not available; —, not detected; ≤, less than or equal to; *, concentration greater than the benchmark level; nc, not collected]
50 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Table 8. Nutrients detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and 

Assessment (GAMA) study unit, California, October to December 2010.

[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites 

were analyzed, but only samples with detections are listed. Information about the constituents given in table 3E. GAMA site identification number: KLAM, 

Klamath Mountains study unit; KLAM-U, Klamath Mountains study unit understanding site. Benchmark type, benchmark level, and LT-MDL as of October 1, 

2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA 

when the MCL-CA is lower than the MCL-US or no MCL-US exists. HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory 

level; MCL-US, USEPA maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; LT-MDL, long-term method detection limit; 

mg/L, milligrams per liter; na, not available; —, not detected]

GAMA 

site 

identification 

number

Ammonia 

(as nitrogen) 

(mg/L) 

(00608)

Nitrite 

(as nitrogen) 

(mg/L) 

(00613)

Nitrite plus nitrate 

(as nitrogen) 1

(mg/L) 

(00631)

Total nitrogen 

(ammonia + nitrate + nitrite + 

organic nitrogen) 

(mg/L) 

(62854)

Phosphate, 

orthophosphate 

(as phosphorus) 

(mg/L) 

(00671)

Benchmark type HAL-US MCL-US MCL-US na na

Benchmark level 2

 24.7 1 10 na na

[LT-MDL] [0.01] [0.001] [0.02] [0.05] [0.006]

KLAM grid sites (38 sites sampled)

KLAM-01 — — — — 0.006

KLAM-02 — — — — 0.011

KLAM-03 — — 0.27 0.26 0.025

KLAM-04 — — 0.07 — 0.014

KLAM-05 — — 0.06 — 0.036

KLAM-06 0.29 — — 0.25 0.010

KLAM-07 — — 0.17 0.15 0.018

KLAM-08 0.06 0.002 0.03 0.06 0.007

KLAM-09 — — 0.08 0.07 0.012

KLAM-10 — — 0.03 — 0.035

KLAM-11 — — 0.06 0.05 0.016

KLAM-12 — — 0.03 — 0.022

KLAM-13 0.01 — 0.08 0.07 0.018

KLAM-14 — — 0.35 0.35 0.037

KLAM-15 — — 0.19 0.17 0.015

KLAM-16 — — 0.11 0.10 0.024

KLAM-17 — — 0.58 0.61 0.024

KLAM-18 0.01 — — — 0.017

KLAM-19 0.01 — 0.08 0.12 0.029

KLAM-20 — — 0.04 — 0.026

KLAM-21 — — 0.05 — 0.022

KLAM-22 — — 0.20 0.20 0.017

KLAM-23 — — 0.17 0.18 0.028

KLAM-25 0.03 — — — 0.029

KLAM-26 — — 2.56 2.57 0.035
Tables 51

GAMA 

site 

identification 

number

Ammonia 

(as nitrogen) 

(mg/L) 

(00608)

Nitrite 

(as nitrogen) 

(mg/L) 

(00613)

Nitrite plus nitrate 

(as nitrogen) 1

(mg/L) 

(00631)

Total nitrogen 

(ammonia + nitrate + nitrite + 

organic nitrogen) 

(mg/L) 

(62854)

Phosphate, 

orthophosphate 

(as phosphorus) 

(mg/L) 

(00671)

Benchmark type HAL-US MCL-US MCL-US na na

Benchmark level 2

 24.7 1 10 na na

[LT-MDL] [0.01] [0.001] [0.02] [0.05] [0.006]

KLAM grid sites (38 sites sampled)—Continued

KLAM-27 — — — — 0.026

KLAM-28 — — 0.03 — 0.015

KLAM-29 — — 0.23 0.23 0.075

KLAM-30 0.06 — — — 0.025

KLAM-31 0.02 — 0.03 — 0.010

KLAM-32 — — 0.05 — 0.030

KLAM-33 0.04 0.002 0.06 0.07 0.073

KLAM-34 — — 1.85 1.95 0.020

KLAM-35 — — 0.04 — 0.016

KLAM-36 — — 0.04 0.07 0.011

KLAM-37 — — 1.57 1.69 0.039

KLAM-38 — — — — 0.012

KLAM understanding site

KLAM-U-01 — — 0.05 — 0.018

1

 Nitrite plus nitrate (as nitrogen) is referred to as nitrate in the text for clarity.

2

 The HAL-US is 30 mg/L “as ammonia.” To facilitate comparison to the analytical results, we have converted and reported this HAL-US as 24.7 mg/L “as 

nitrogen.”

Table 8. Nutrients detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and 

Assessment (GAMA) study unit, California, October to December 2010.—Continued

[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites 

were analyzed, but only samples with detections are listed. Information about the constituents given in table 3E. GAMA site identification number: KLAM, 

Klamath Mountains study unit; KLAM-U, Klamath Mountains study unit understanding site. Benchmark type, benchmark level, and LT-MDL as of October 1, 

2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA 

when the MCL-CA is lower than the MCL-US or no MCL-US exists. HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory 

level; MCL-US, USEPA maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; LT-MDL, long-term method detection limit; 

mg/L, milligrams per liter; na, not available; —, not detected]
Table 9. Major and minor ions, silica, and total dissolved solids (TDS) detected in samples collected for the Klamath Mountains (KLAM) Groundwate

Assessment (GAMA) study unit, California, October to December 2010. [The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were analyzed. Inform

given in table 3F. GAMA site identification number: KLAM, Klamath Mountains study unit; KLAM-U, Klamath Mountains study unit understanding site. Benchmark type, b

as of October 1, 2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-US or no MCL-US exists. The SMCL-CA benchmark for chloride, sulfate, and TDS have recommended and upper benchmark levels. The upper benchmark level is shCalifornia Department of Public Health (CDPH) maximum contaminant level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Glong-term method detection limit; mg/L, milligrams per liter; SiO2, silicon dioxide; na, not available; —, not detected; *, concentration greater than the recommended benchmar

GAMA site identification number Bromide (mg/L) (71870) Calcium (mg/L) (00915) Chloride (mg/L) (00940) Fluoride (mg/L) (00950) Iodide (mg/L) (71865) Magnesium (mg/L) (00925) Potassium (mg/L) (00935) Sodium (mg/L) (00930) Sulfate (mg/L) (00945) 

Benchmark type na na SMCL-CA MCL-CA na na na na SMCL-CA Benchmark level na na 250 (500) 2 na na na na 250 (500) [LT-MDL] [0.01] [0.022] [0.06] [0.04] [0.002] [0.008] [0.022] [0.06] [0.09] KLAM grid sites (38 sites sampled) KLAM-01 — 1.15 2.59 — — 23.2 0.05 1.56 1.07 

KLAM-02 — 14.9 0.53 0.06 — 8.67 2.79 3.27 11.5 

KLAM-03 0.02 59.1 7.22 0.09 — 8.77 0.58 12.4 21.0 

KLAM-04 — 5.36 0.57 — — 5.53 0.60 3.61 3.71 

KLAM-05 — 58.5 0.35 0.11 — 12.1 0.69 3.98 13.5 

KLAM-06 0.73 22.6 *454 0.23 0.094 2.27 0.63 303 22.1 

KLAM-07 — 36.0 0.90 0.09 — 20.1 0.29 7.59 3.36 

KLAM-08 — 41.7 2.35 0.08 — 6.13 0.73 10.7 20.6 

KLAM-09 0.01 44.1 2.02 0.12 — 3.96 1.35 5.65 18.0 

KLAM-10 — 5.08 0.90 — — 3.05 0.29 2.85 1.56 

KLAM-11 — 28.9 1.00 0.07 — 6.74 0.36 3.55 9.20 

KLAM-12 — 16.1 0.39 0.05 — 6.34 0.20 4.60 0.24 

KLAM-13 — 29.0 1.80 0.07 — 13.3 0.30 4.17 4.96 

KLAM-14 0.01 72.4 1.66 0.16 — 15.1 0.84 6.99 16.7 

KLAM-15 — 58.8 1.78 0.08 — 6.14 0.94 4.98 13.5 
GAMA 

site 

identification 

number

Bromide 

(mg/L) 

(71870) 

Calcium 

(mg/L) 

(00915) 

Chloride 

(mg/L) 

(00940) 

Fluoride 

(mg/L) 

(00950) 

Iodide 

(mg/L) 

(71865)

Magnesium 

(mg/L) 

(00925) 

Potassium 

(mg/L) 

(00935) 

Sodium 

(mg/L) 

(00930) 

Sulfate 

(mg/L) 

(00945) 

Benchmark type na na SMCL-CA MCL-CA na na na na SMCL-CA Benchmark level na na 250 (500) 2 na na na na 250 (500) [LT-MDL] [0.01] [0.022] [0.06] [0.04] [0.002] [0.008] [0.022] [0.06] [0.09] KLAM grid sites (38 sites sampled)—ContinuedKLAM-16 — 5.82 0.66 0.11 — 3.12 0.23 5.59 4.25 

KLAM-17 — 24.6 1.63 0.11 — 8.69 1.05 9.07 4.54 

KLAM-18 — 9.52 0.42 — — 3.77 0.45 3.28 0.18 

KLAM-19 — 21.1 0.84 0.08 — 10.9 0.28 3.18 2.23 

KLAM-20 — 6.80 0.50 — — 26.3 0.44 2.63 0.22 

KLAM-21 — 26.0 1.06 0.07 — 25.7 4.12 4.73 2.29 

KLAM-22 — 20.5 2.57 — — 13.9 0.43 3.17 10.7 

KLAM-23 — 32.7 3.61 0.07 0.001 11.9 4.18 9.73 21.2 

KLAM-24 — 59.0 1.76 0.11 0.002 25.8 2.70 16.3 68.3 

KLAM-25 — 60.4 2.72 0.23 0.001 7.85 0.35 11.9 27.6 

KLAM-26 0.01 30.0 6.20 — 0.002 15.3 1.13 9.07 10.8 

KLAM-27 — 29.0 2.04 0.16 — 8.01 0.52 11.3 50.7 

KLAM-28 — 17.3 0.80 0.04 — 3.63 0.17 4.75 7.43 

KLAM-29 — 9.90 2.62 0.04 — 4.54 1.95 6.27 0.78 

KLAM-30 0.06 26.9 15.7 0.07 0.007 18.3 1.09 17.5 9.41 

Table 9. Major and minor ions, silica, and total dissolved solids (TDS) detected in samples collected for the Klamath Mountains (KLAM) GroundwateAssessment (GAMA) study unit, California, October to December 2010.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were analyzed. Informgiven in table 3F. GAMA site identification number: KLAM, Klamath Mountains study unit; KLAM-U, Klamath Mountains study unit understanding site. Benchmark type, b

as of October 1, 2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-US or no MCL-US exists. The SMCL-CA benchmark for chloride, sulfate, and TDS have recommended and upper benchmark levels. The upper benchmark level is shCalifornia Department of Public Health (CDPH) maximum contaminant level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Glong-term method detection limit; mg/L, milligrams per liter; SiO2, silicon dioxide; na, not available; —, not detected; *, concentration greater than the recommended benchmar
GAMA site identification number Bromide (mg/L) (71870) Calcium (mg/L) (00915) Chloride (mg/L) (00940) Fluoride (mg/L) (00950) Iodide (mg/L) (71865) Magnesium (mg/L) (00925) Potassium (mg/L) (00935) Sodium (mg/L) (00930) Sulfate (mg/L) (00945) 

Benchmark type na na SMCL-CA MCL-CA na na na na SMCL-CA Benchmark level na na 250 (500) 2 na na na na 250 (500) [LT-MDL] [0.01] [0.022] [0.06] [0.04] [0.002] [0.008] [0.022] [0.06] [0.09] KLAM grid sites (38 sites sampled)—Continued KLAM-31 — 2.60 4.05 — 0.006 93.3 0.34 4.80 3.93 

KLAM-32 — 29.5 0.73 0.14 — 7.81 0.40 8.49 4.19 

KLAM-33 0.02 8.55 7.89 0.12 0.013 2.45 0.33 28.6 7.12 

KLAM-34 0.03 83.8 8.43 0.06 — 6.42 0.32 7.66 53.0 

KLAM-35 — 20.6 0.74 0.09 — 14.5 0.09 7.15 6.12 

KLAM-36 — 5.43 1.36 — — 14.5 0.23 2.15 1.16 

KLAM-37 — 10.4 13.6 0.08 — 9.72 0.98 11.5 14.4 

KLAM-38 — 19.0 0.61 — — 8.84 0.24 5.77 13.0 

KLAM understanding site KLAM-U-01 — 73.1 1.26 0.14 — 8.86 2.97 5.56 38.6 

Table 9. Major and minor ions, silica, and total dissolved solids (TDS) detected in samples collected for the Klamath Mountains (KLAM) GroundwateAssessment (GAMA) study unit, California, October to December 2010.—Continued [The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were analyzed. Informgiven in table 3F. GAMA site identification number: KLAM, Klamath Mountains study unit; KLAM-U, Klamath Mountains study unit understanding site. Benchmark type, b

as of October 1, 2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-US or no MCL-US exists. The SMCL-CA benchmark for chloride, sulfate, and TDS have recommended and upper benchmark levels. The upper benchmark level is shCalifornia Department of Public Health (CDPH) maximum contaminant level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Glong-term method detection limit; mg/L, milligrams per liter; SiO2, silicon dioxide; na, not available; —, not detected; *, concentration greater than the recommended benchmar
Tables 55

GAMA 

site 

identification 

number

Arsenic 

(total) 

(99033) 

(μg/L)

Arsenic-III 

(99034) 

(μg/L) 

Iron 

(total) 

(01046) 

(μg/L) 

Iron-II 

(01047) 

(μg/L) 

Benchmark type MCL-US na SMCL-CA na

Benchmark level 10 na 300 na

[MDL] [0.5] [1] [2] [2]

KLAM grid sites (38 sites sampled)

KLAM-01 — — 3 —

KLAM-02 — — 10 9

KLAM-03 E0.2 — 36 32

KLAM-05 0.5 — — —

KLAM-06 — — 31 31

KLAM-07 1.0 — — —

KLAM-08 E0.4 — 259 238

KLAM-09 — — 178 175

KLAM-11 E0.4 — — —

KLAM-12 — — 11 6

KLAM-13 — — 6 5

KLAM-14 E0.3 — — —

KLAM-17 E0.3 — — —

KLAM-18 — — *394 380

KLAM-19 4.3 — 6 6

KLAM-21 0.6 — — —

KLAM-22 E0.3 — 38 31

KLAM-23 0.8 — 9 4

KLAM-24 — — *490 463

KLAM-25 0.5 — 245 234

GAMA 

site 

identification 

number

Arsenic 

(total) 

(99033) 

(μg/L)

Arsenic-III 

(99034) 

(μg/L) 

Iron 

(total) 

(01046) 

(μg/L) 

Iron-II 

(01047) 

(μg/L) 

Benchmark type MCL-US na SMCL-CA na

Benchmark level 10 na 300 na

[MDL] [0.5] [1] [2] [2]

KLAM grid sites (38 sites sampled)—Continued

KLAM-26 — — 14 11

KLAM-27 — — 55 47

KLAM-28 — — 10 10

KLAM-29 E0.2 — 7 4

KLAM-30 — — *2,940 2,890

KLAM-32 — — 24 19

KLAM-33 0.8 — 6 3

KLAM-34 — — 56 33

KLAM-36 — — 5 4

KLAM-37 — — 37 25

KLAM-38 — — 3 3

KLAM understanding site

KLAM-U-01 1.0 — 8 —

Table 10. Arsenic and iron species detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient 

Monitoring and Assessment (GAMA) study unit, California, October to December 2010.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Information about the constituents given in table 3G. 

Samples from all 39 sites were analyzed, but only samples with detections are listed. GAMA site identification number: KLAM, Klamath Mountains 

study unit; KLAM-U, Klamath Mountains study unit understanding site. Benchmark type, benchmark level, and MDL as of October 1, 2010. Benchmark 

type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is 

lower than the MCL-US or no MCL-US exists. MCL-CA, California Department of Public Health maximum contaminant level; SMCL-CA, CDPH secondary 

maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; MDL, method detection limit; na, not available; μg/L, micrograms per liter; 

E, estimated or having a higher degree of uncertainty; *, concentration greater than the benchmark level; —, not detected]
56 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

GAMA site 

identification 

number

δ2

H in 

water 

(per mil) 

(82082)

δ18O in 

water 

(per mil) 

(82085)

Isotopic ratio 

of Sr in water 

(

87Sr/86Sr) 

(atom ratio) 

(75978)

δ13C in 

dissolved 

inorganic 

carbon 

(per mil) 

(82081)

14C in 

water 

(percent 

modern) 

(49933)

Benchmark 

type

na na na na na

Benchmark 

level

na na na na na

KLAM grid sites (38 sites sampled)

KLAM-01 –57.8 –8.75 0.70626 –11.15 90.37

KLAM-02 –88.1 –12.17 0.70720 –20.85 104.2

KLAM-03 –93.3 –12.01 0.70554 –15.19 85.06

KLAM-04 –104 –14.41 0.71327 –19.28 103.4

KLAM-05 –98.1 –13.52 0.70511 –12.63 98.45

KLAM-06 –103 –13.24 0.70615 –16.31 38.86

KLAM-07 –82.2 –11.30 0.70532 –16.55 94.33

KLAM-08 –59.2 –9.10 0.70541 –13.36 48.36

KLAM-09 –66.9 –9.62 0.70551 –18.40 75.52

KLAM-10 –70.0 –10.17 0.70600 –20.61 95.41

KLAM-11 –69.3 –10.08 0.70406 –17.84 106.7

KLAM-12 –84.3 –11.94 0.70730 –19.79 95.10

KLAM-13 –79.5 –11.27 0.70446 –15.56 104.2

KLAM-14 –73.4 –10.33 0.71348 –14.79 100.3

KLAM-15 –74.3 –10.61 0.71306 –14.19 100.7

KLAM-16 –65.7 –9.78 0.70738 –21.74 96.63

KLAM-17 –87.8 –11.51 0.70606 –20.05 104.2

KLAM-18 –85.3 –12.10 0.70692 –21.08 95.53

KLAM-19 –72.9 –9.21 0.70692 –13.38 102.6

KLAM-20 –87.2 –12.15 0.70482 –21.34 94.60

GAMA site 

identification 

number

δ2

H in 

water 

(per mil) 

(82082)

δ18O in 

water 

(per mil) 

(82085)

Isotopic ratio 

of Sr in water 

(

87Sr/86Sr) 

(atom ratio) 

(75978)

δ13C in 

dissolved 

inorganic 

carbon 

(per mil) 

(82081)

14C in 

water 

(percent 

modern) 

(49933)

Benchmark 

type

na na na na na

Benchmark 

level

na na na na na

KLAM grid sites (38 sites sampled)—Continued

KLAM-21 –86.9 –12.00 0.70717 –17.22 95.14

KLAM-22 –64.3 –9.40 0.70576 –13.80 96.17

KLAM-23 –85.6 –11.81 0.70513 –18.32 96.74

KLAM-24 –94.9 –12.27 0.71048 –14.38 78.07

KLAM-25 –63.9 –9.60 0.70796 –19.28 77.21

KLAM-26 –66.2 –9.61 0.70547 –18.12 110.6

KLAM-27 –63.6 –9.56 0.70663 –20.32 103.9

KLAM-28 –64.9 –9.90 0.70623 –16.40 97.17

KLAM-29 –90.8 –12.98 0.70405 –13.53 63.98

KLAM-30 –77.8 –11.28 0.70431 –17.19 56.22

KLAM-31 –99.7 –13.05 0.70518 –14.62 75.63

KLAM-32 –65.5 –9.72 0.70538 –18.80 88.25

KLAM-33 –72.4 –10.64 0.71107 –15.84 47.02

KLAM-34 –63.7 –9.59 0.70665 –13.75 71.40

KLAM-35 –64.0 –9.68 0.70608 –18.71 96.61

KLAM-36 –91.9 –12.97 0.70449 –14.92 104.5

KLAM-37 –77.7 –10.77 0.70651 –19.97 100.7

KLAM-38 –79.8 –11.24 0.70519 –13.57 101.6

KLAM understanding site

KLAM-U-01 –76.7 –10.56 0.71309 –14.53 88.39

Table 11. Isotopic tracers detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and 

Assessment (GAMA) study unit, California, October to December 2010.

[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Information about the 

constituents given in table 3H. Samples from all 39 sites were analyzed. Stable isotope ratios of hydrogen, oxygen, and carbon are reported in the standard delta 

notation (δ), the ratio of a heavier isotope to more common lighter isotope of that element, relative to a standard reference material. Isotopic ratios of strontium 

in water are reported as the abundance of atoms of the heavier isotope to the lighter isotope of the element. GAMA site identification number: KLAM, 

Klamath Mountains study unit; KLAM-U, Klamath Mountains study unit understanding site. Other abbreviations: USGS, U.S. Geological Survey; H, 

hydrogen; O, oxygen; Sr, strontium; 14C, carbon-14; na, not available]
Tables 57

Table 12. Results for the Lawrence Livermore National Laboratory (LLNL) analyses of tritium, dissolved noble gases, and helium 

isotope ratios in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study 

unit, California, October to December 2010.

[The five-digit number in parentheses below the constituent name is the USGS parameter code used to uniquely identify a specific constituent or property. 

GAMA site identification number: KLAM, Klamath Mountains study unit; KLAM-U, Klamath Mountains study unit understanding site. Measurement errors: 

Helium-3/helium-4 ratios, helium-4, krypton, neon, and xenon have 2-percent errors; argon has 3-percent errors; errors for modeled recharge temperature are 

less than 1 °C for 82 percent of the samples. Benchmark type and benchmark level as of October 1, 2010. Benchmark type: Maximum contaminant level 

benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no 

MCL-US exists. MCL-CA, California Department of Public Health maximum contaminant level. Abbreviations: cm3 STP/g, cubic centimeters at standard 

temperature and pressure per gram of water; °C, degrees Celsius; na, not available; pCi/L, picocuries per liter; CSU, 1-sigma combined standard uncertainty; 

—, not detected; ±, plus or minus; nc, not collected]

GAMA site 

identification 

number

Tritium 

(pCi/L) 

(07000)

Helium-3/ 

Helium-4 

(atom ratio) 

(61040)

Helium-4 

(cm3 STP/g) 

(85561)

Neon 

(cm3 STP/g) 

(61046)

Argon 

(cm3 STP/g) 

(85563)

Krypton 

(cm3 STP/g) 

(85565)

Xenon 

(cm3 STP/g) 

(85567)

Modeled 

recharge 

temperature 

(°C)

Benchmark type MCL-CA na na na na na na na

Benchmark level 20,000 na na na na na na na

[RL] result ± CSU x 10–7 x 10–7 x 10–7 x 10–4 x 10–8 x 10–8 0.1

KLAM grid sites (38 sites sampled)

KLAM-01 2.2 ± 0.18 13.44 0.69 2.29 3.58 8.05 1.17 14.1

KLAM-02 2.4 ± 0.18 13.45 0.78 3.58 6.44 14.85 2.45 11.5

KLAM-03 1.9 ± 0.18 7.24 0.98 2.08 3.42 7.86 1.14 13.1

KLAM-04 2.9 ± 0.18 13.73 0.79 3.39 4.41 9.89 1.35 5.7

KLAM-05 2.5 ± 0.18 13.37 0.69 2.78 3.35 8.43 1.20 11.5

KLAM-06 0.40 ± 0.18 10.17 51.41 3.61 4.52 10.04 1.50 6.8

KLAM-07 2.0 ± 0.18 11.82 0.83 2.77 3.95 8.60 1.17 13.0

KLAM-08 2.1 ± 0.18 13.18 0.67 2.74 4.17 9.45 1.20 12.4

KLAM-09 2.3 ± 0.18 3.93 3.01 2.16 3.61 8.24 1.26 12.2

KLAM-10 2.4 ± 0.18 13.72 0.63 2.79 4.78 11.28 1.62 3.2

KLAM-11 2.6 ± 0.18 13.68 0.63 2.63 3.70 8.34 1.10 15.2

KLAM-12 3.5 ± 0.18 nc nc nc nc nc nc nc

KLAM-13 2.9 ± 0.18 13.68 0.47 2.04 3.48 8.18 1.13 13.0

KLAM-14 2.8 ± 0.18 9.84 0.65 2.23 3.82 7.10 1.09 11.5

KLAM-15 2.4 ± 0.18 8.91 1.88 2.77 4.23 9.44 1.29 11.0

KLAM-16 3.4 ± 0.18 15.64 0.72 3.03 4.30 9.28 1.26 11.9

KLAM-17 1.9 ± 0.18 9.09 0.79 2.25 3.77 8.84 1.24 8.4

KLAM-18 2.3 ± 0.18 14.55 0.80 3.40 4.43 9.42 1.34 7.9

KLAM-19 2.7 ± 0.18 13.81 0.57 2.39 3.57 7.94 1.09 14.3

KLAM-20 1.4 ± 0.18 14.10 0.43 1.90 3.60 8.51 1.24 11.5

KLAM-21 1.8 ± 0.18 13.79 0.49 1.90 3.18 7.47 1.06 14.3

KLAM-22 2.0 ± 0.18 13.87 1.49 6.03 7.84 15.06 1.91 6.4

KLAM-23 1.4 ± 0.18 10.84 0.88 2.71 3.89 8.37 1.16 12.7

KLAM-24 1.5 ± 0.18 5.72 3.78 5.77 5.87 11.52 1.59 5.0

KLAM-25 2.8 ± 0.18 11.08 0.80 2.78 3.89 8.59 1.26 12.1
58 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

GAMA site 

identification 

number

Tritium 

(pCi/L) 

(07000)

Helium-3/ 

Helium-4 

(atom ratio) 

(61040)

Helium-4 

(cm3 STP/g) 

(85561)

Neon 

(cm3 STP/g) 

(61046)

Argon 

(cm3 STP/g) 

(85563)

Krypton 

(cm3 STP/g) 

(85565)

Xenon 

(cm3 STP/g) 

(85567)

Modeled 

recharge 

temperature 

(°C)

Benchmark type MCL-CA na na na na na na na

Benchmark level 20,000 na na na na na na na

[RL] result ± CSU x 10–7 x 10–7 x 10–7 x 10–4 x 10–8 x 10–8 0.1

KLAM grid sites (38 sites sampled)—Continued

KLAM-26 2.4 ± 0.18 14.34 6.68 14.83 8.47 14.25 1.67 11.5

KLAM-27 2.4 ± 0.18 13.54 0.45 1.84 3.36 7.86 1.04 14.7

KLAM-28 2.8 ± 0.18 14.10 0.51 2.15 3.65 8.46 1.24 11.5

KLAM-29 2.4 ± 0.18 24.73 0.52 1.92 3.65 8.71 1.26 8.5

KLAM-30 0.25 ± 0.18 44.85 2.61 2.91 4.29 9.74 1.39 7.5

KLAM-31 2.8 ± 0.18 6.02 18.06 2.09 4.31 8.72 1.23 11.5

KLAM-32 3.4 ± 0.18 14.89 0.88 3.70 4.67 9.71 1.25 14.2

KLAM-33 1.6 ± 0.18 9.86 2.64 3.24 4.35 9.24 1.10 18.0

KLAM-34 2.9 ± 0.18 13.68 1.44 5.16 5.38 9.73 1.25 14.5

KLAM-35 2.5 ± 0.18 13.95 0.67 2.97 4.22 9.17 1.22 13.3

KLAM-36 3.0 ± 0.18 13.27 0.45 2.03 3.94 9.07 1.36 6.6

KLAM-37 2.5 ± 0.18 13.91 0.48 2.16 3.28 7.63 1.11 14.2

KLAM-38 2.6 ± 0.18 13.87 0.48 2.11 3.58 8.39 1.24 10.4

KLAM understanding site

KLAM-U-01 2.6 ± 0.18 12.50 0.49 1.94 3.43 8.07 1.11 13.5

Table 12. Results for the Lawrence Livermore National Laboratory (LLNL) analyses of tritium, dissolved noble gases, and helium 

isotope ratios in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study

unit, California, October to December 2010.—Continued

[The five-digit number in parentheses below the constituent name is the USGS parameter code used to uniquely identify a specific constituent or property. 

GAMA site identification number: KLAM, Klamath Mountains study unit; KLAM-U, Klamath Mountains study unit understanding site. Measurement 

errors: Helium-3/helium-4 ratios, helium-4, krypton, neon, and xenon have 2-percent errors; argon has 3-percent errors; errors for modeled recharge 

temperature are <1 °C for 82 percent of the samples. Benchmark type and benchmark level as of October 1, 2010. Benchmark type: Maximum contaminant 

level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no 

MCL-US exists. MCL-CA, California Department of Public Health maximum contaminant level. Abbreviations: cm3 STP/g, cubic centimeters at standard 

temperature and pressure per gram of water; °C, degrees Celsius; na, not available; pCi/L, picocuries per liter; CSU, 1-sigma combined standard uncertainty; 

—, not detected; ±, plus or minus; nc, not collected]
Table 13. Uranium and other radioactive constituents detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Moni

(GAMA) study unit, California, October to December 2010.

[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were analyzed, with thKLAM-12. Information about the constituents given in table 3H. Measured values less than the sample-specific critical level (ssLC) are reported as non-detections (—). Tritium a

than the ssLC; therefore, the ssLC is not reported. GAMA site identification number: KLAM, Klamath Mountains study unit; KLAM-U, Klamath Mountains study unit underst

benchmark level as of October 1, 2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and ais lower than the MCL-US or no MCL-US exists. MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Helevel. Other abbreviations: USGS, U.S. Geological Survey; RL, reporting level; CSU, 1-sigma combined standard uncertainty; pCi/L, picocuries per liter; μg/L, micrograms peor minus; nc, not collected]

GAMA site 

identification number

Uranium 

(μg/L) 

(22703)

Radon-222 

(pCi/L) 

(82303)

Gross alpha radioactivity, 

72-hour count 

(pCi/L) 

(62636)

Gross alpha radioactivity, 

30-day count 

(pCi/L) 

(62639)

Gross beta radioactivity, 

72-hour count 

(pCi/L) 

(62642)

Gross beta r

30-day 

(pC

(62

Benchmark type MCL-US Proposed MCL-US MCL-US MCL-US MCL-CA MC

Benchmark level 30 4,000 15 15 50 5

[RL] [0.004] Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC Result ± CSU 

KLAM grid sites (38 sites sampled)KLAM-01 — — 13 — 0.28 — 0.37 — 0.40 — 

KLAM-02 0.033 500 ± 31 11 — 0.27 — 0.24 2.82 ± 0.34 0.42 1.7 ± 0.41 

KLAM-03 0.226 420 ± 27 14 0.84 ± 0.44 0.56 1.02 ± 0.56 0.63 — 0.84 — 

KLAM-04 0.012 460 ± 29 12 0.71 ± 0.22 0.23 — 0.66 — 0.42 1.19 ± 0.55 

KLAM-05 0.183 270 ± 20 13 — 0.44 1.06 ± 0.43 0.50 — 0.57 — 

KLAM-06 0.013 280 ± 20 12 2.29 ± 0.83 0.73 — 1.0 1.26 ± 0.75 1.2 — 

KLAM-07 0.026 71 ± 13 17 — 1 0.41 0.76 ± 0.51 0.65 1 0.58 ± 0.34 0.53 1.84 ± 0.61 

KLAM-08 0.023 152 ± 15 15 1 0.73 ± 0.48 0.58 — 1.0 — 1 0.63 — 

KLAM-09 0.126 420 ± 28 14 — 1 0.66 2.28 ± 0.88 0.74 1 0.88 ± 0.44 0.67 — 

KLAM-10 — 450 ± 29 13 — 0.33 — 0.55 — 0.92 0.93 ± 0.55 

KLAM-11 0.034 590 ± 36 13 — 0.52 — 0.91 — 0.60 — KLAM-12 0.005 nc — 0.43 — 0.61 — 0.74 — 

KLAM-13 0.030 199 ± 16 14 — 0.54 — 0.65 — 0.65 — KLAM-14 0.497 450 ± 28 12 1.36 ± 0.52 0.57 — 0.88 0.70 ± 0.43 0.66 — 

KLAM-15 0.339 410 ± 26 12 — 0.45 — 0.88 — 0.71 — 
GAMA site identification number Uranium (μg/L) (22703) Radon-222 (pCi/L) (82303) Gross alpha radioactivity, 72-hour count (pCi/L) (62636) Gross alpha radioactivity, 30-day count (pCi/L) (62639) Gross beta radioactivity, 72-hour count (pCi/L) (62642) Gross beta r

30-day 

(pC

(62

Benchmark type MCL-US Proposed MCL-US MCL-US MCL-US MCL-CA MC

Benchmark level 30 4,000 15 15 50 5

[RL] [0.004] Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC Result ± CSU 

KLAM grid sites (38 sites sampled)—Continued KLAM-16 — 2,670 ± 150 13 — 0.35 — 0.18 0.67 ± 0.27 0.42 0.78 ± 0.37 

KLAM-17 0.923 1,630 ± 91 13 0.67 ± 0.35 0.48 — 0.6 1.08 ± 0.28 0.41 1.1 ± 0.40 

KLAM-18 — 79 ± 11 13 — 0.36 — 0.38 0.62 ± 0.27 0.42 — 

KLAM-19 0.054 85 ± 11 13 — 0.40 — 0.65 — 0.52 — 

KLAM-20 0.099 340 ± 23 13 0.25 ± 0.18 0.23 — 0.39 — 0.45 — 

KLAM-21 3.22 1,830 ± 100 12 2.08 ± 0.48 0.42 1.84 ± 0.63 0.59 4.31 ± 0.41 0.42 4.93 ± 0.57 

KLAM-22 0.005 149 ± 17 18 — 0.31 — 0.46 0.52 ± 0.26 0.41 — KLAM-23 0.349 600 ± 38 18 — 0.48 — 0.47 3.64 ± 0.39 0.44 3.7 ± 0.50 KLAM-24 0.252 1,660 ± 92 11 9.6 ± 1.4 0.72 1.84 ± 0.53 0.51 5.07 ± 0.53 0.61 3.9 ± 0.46 

KLAM-25 0.020 65 ± 9.1 11 — 0.58 — 0.59 — 0.72 — 

KLAM-26 0.037 59 ± 8.7 11 — 0.52 — 0.74 1.03 ± 0.32 0.48 — KLAM-27 0.004 38 ± 9.3 13 — 0.52 — 0.67 — 0.41 — 

KLAM-28 0.007 212 ± 17 14 — 0.3 — 0.44 — 0.41 — KLAM-29 0.074 1,240 ± 70 12 — 0.42 — 0.49 1.55 ± 0.28 0.40 1.88 ± 0.45 KLAM-30 0.011 237 ± 17 12 — 0.95 — 0.56 1.58 ± 0.66 0.94 0.93 ± 0.43 

Table 13. Uranium and other radioactive constituents detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Moni(GAMA) study unit, California, October to December 2010.—Continued [The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were analyzed, with thKLAM-12. Information about the constituents given in table 3H. Measured values less than the sample-specific critical level (ssLC) are reported as non-detections (—). Tritium a

than the ssLC; therefore, the ssLC is not reported. GAMA site identification number: KLAM, Klamath Mountains study unit; KLAM-U, Klamath Mountains study unit underst

benchmark level as of October 1, 2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and ais lower than the MCL-US or no MCL-US exists. MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Helevel. Other abbreviations: USGS, U.S. Geological Survey; RL, reporting level; CSU, 1-sigma combined standard uncertainty; pCi/L, picocuries per liter; μg/L, micrograms peor minus; nc, not collected]
GAMA site 

identification number

Uranium 

(μg/L) 

(22703)

Radon-222 

(pCi/L) 

(82303)

Gross alpha radioactivity, 

72-hour count 

(pCi/L) 

(62636)

Gross alpha radioactivity, 

30-day count 

(pCi/L) 

(62639)

Gross beta radioactivity, 

72-hour count 

(pCi/L) 

(62642)

Gross beta r

30-day 

(pC

(62

Benchmark type MCL-US Proposed MCL-US MCL-US MCL-US MCL-CA MC

Benchmark level 30 4,000 15 15 50 5

[RL] [0.004] Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC Result ± CSU 

KLAM grid sites (38 sites sampled)—ContinuedKLAM-31 — — 14 — 0.42 — 0.59 — 0.47 — 

KLAM-32 0.039 410 ± 26 12 — 0.44 0.46 ± 0.35 0.44 — 0.69 — 

KLAM-33 0.022 1,200 ± 67 12 0.42 ± 0.28 0.37 — 0.54 — 0.42 — 

KLAM-34 0.130 320 ± 23 14 — 0.67 — 0.98 — 0.86 — 

KLAM-35 0.004 68 ± 10 13 — 0.35 — 0.50 — 0.67 — 

KLAM-36 — 54 ± 9.0 12 — 0.21 0.41 ± 0.27 0.33 — 0.42 — 

KLAM-37 0.008 1,330 ± 76 15 — 1 0.38 — 0.46 1 0.76 ± 0.26 0.40 — 

KLAM-38 0.010 91 ± 12 14 — 0.35 — 0.51 — 0.45 — 

KLAM understanding siteKLAM-U-01 0.662 630 ± 38 13 — 0.75 — 0.66 2.76 ± 0.46 0.63 1.73 ± 0.47 

1 Counted 4-6 days after sample collection.

Table 13. Uranium and other radioactive constituents detected in samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Moni(GAMA) study unit, California, October to December 2010.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 39 sites were analyzed, with thKLAM-12. Information about the constituents given in table 3H. Measured values less than the sample-specific critical level (ssLC) are reported as non-detections (—). Tritium a

than the ssLC; therefore, the ssLC is not reported. GAMA site identification number: KLAM, Klamath Mountains study unit; KLAM-U, Klamath Mountains study unit underst

benchmark level as of October 1, 2010. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and ais lower than the MCL-US or no MCL-US exists. MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Helevel. Other abbreviations: USGS, U.S. Geological Survey; RL, reporting level; CSU, 1-sigma combined standard uncertainty; pCi/L, picocuries per liter; μg/L, micrograms peor minus; nc, not collected]
62 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Table 14. Microbial indicators detected in samples collected for 

the Klamath Mountains (KLAM) Groundwater Ambient Monitoring 

and Assessment (GAMA) study unit, California, October to 

December 2010.

[The five-digit USGS parameter code below the constituent name is used 

to uniquely identify a specific constituent or property. Samples from all 39 

sites were analyzed, but only samples with detections are listed. Information 

about the constituents given in table 3I. GAMA site identification number: 

KLAM, Klamath Mountains study unit; KLAM-U, Klamath Mountains study 

unit understanding site. Benchmark type and benchmark level as of October 1, 

2010. Benchmark type: Maximum contaminant level benchmarks are listed 

as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA 

when the MCL-CA is lower than the MCL-US or no MCL-US exists. TT-US, 

U.S. Environmental Protection Agency (USEPA) treatment technique; 

MCL-US, USEPA maximum contaminant level. Other abbreviations: USGS, 

U.S. Geological Survey; %, percent; M, presence verified but not quantified; 

—, not detected]

GAMA site 

identification 

number

Total coliform

(including fecal coliform 

and E. coli) 

(99595)

Escherichia coli 

(E. coli) 

(99596)

Benchmark type MCL-US TT-US

Benchmark level 5% of samples positive 

per month

No fecal coliforms are 

allowed

KLAM grid sites (38 sites sampled)

KLAM-01 M —

KLAM-02 M —

KLAM-04 M —

KLAM-08 M M

KLAM-12 M —

KLAM-20 M —

KLAM-22 M —

KLAM-23 M —

KLAM-25 M —

KLAM-26 M —

KLAM-34 M M

KLAM-36 M —

KLAM-37 M —

KLAM-38 M —

KLAM understanding site

KLAM-U-01 M —
Appendix 63

Appendix 

This appendix includes discussions of the methods used 

to collect and analyze groundwater samples and report the 

resulting water-quality data. These methods were selected to 

obtain representative samples of the groundwater from each 

site and to minimize the potential for contamination of the 

samples or bias in the data. Procedures used to collect and 

assess QC data and the results of the QC assessments also are 

discussed. 

In the KLAM study unit, groundwater samples were 

collected and QA/QC procedures were implemented using 

standard and modified USGS protocols from the NFM 

(U.S. Geological Survey, variously dated; Wilde and others, 

1999, 2004) and the NAWQA Program (Koterba and others, 

1995). The QA plan followed by the NWQL, the primary 

laboratory used to analyze samples for this study, is described 

in Maloney (2005) and Pirkey and Glodt (1998). 

Sample Collection and Analysis

Samples were collected from two types of sites: 

production wells and springs (“springs” in this study unit 

include horizontal wells). Sites classified as production 

wells are vertically drilled into the ground and have pumps 

that bring the groundwater from the aquifer system to land 

surface and into a distribution system. Sites were classified 

as springs if groundwater discharged naturally at land surface 

from the aquifer without a drilled hole or if a well was 

drilled horizontally. A few springs had pumps to transport 

groundwater from the spring site to a storage tank at a higher 

elevation. 

Prior to sampling, each well was pumped continuously 

to purge at least three casing volumes of water from the 

well (Wilde and others, 1999). Wells were sampled using 

Teflon® tubing with brass and stainless-steel fittings attached 

to a sampling point (usually a hose-bib fitting) on the well 

discharge pipe as close to the wellhead as possible. The 

sampling point was located upstream from water-storage tanks 

or wellhead treatment systems (if present). If a chlorinating 

system was attached to the well, the chlorinator was shut 

off, when possible, before the well was purged and sampled, 

in order to clear all chlorine out of the system. The absence 

of free chlorine was verified by using a Hach® field test kit. 

The mobile laboratory could not be parked within 50 ft of 

the sampling point at most of the sampling sites; therefore, 

all samples were collected outdoors by connecting a 1- to 

3-ft length of Teflon® tubing to the sampling point (Lane and 

others, 2003). All fittings and lengths of tubing were cleaned 

between samples (Wilde, 2004).

Most of the springs were plumbed and had sampling 

points on the discharge pipes similar to the sampling points 

found on discharge pipes from wells. Field water-quality 

indicators were measured and samples were collected using 

the same protocols as used for wells. 

One spring (KLAM-12) was not plumbed and discharged 

into a pool from which the water was then pumped into 

the distribution system. For this spring, field water-quality 

parameters were measured by dipping the multi-probe meter 

directly into the water as close to the spring discharge point 

as possible. Groundwater samples were collected by dipping 

bottles into the water as close to the spring discharge point 

as possible. This method was used because the alternative—

pumping water from the pool with a portable peristaltic pump 

through the filtration apparatus—was not logistically possible 

at most of the unplumbed spring sites. In all cases, turbidity 

(measured with a calibrated turbidity meter) was less than 

0.5 nephelometric turbidity units (NTU) and the samples were 

collected unfiltered, but marked as filtered for analysis. 

For the field measurements, groundwater was pumped 

through a flow-through chamber (attached to the sampling 

point) fitted with a multi-probe meter that simultaneously 

measures the field water-quality indicators—dissolved 

oxygen, temperature, pH, and specific conductance. Field 

measurements were made in accordance with protocols in the 

USGS NFM (Radtke and others, 2005; Wilde and Radtke, 

2005; Lewis, 2006; Wilde, 2006; Wilde and others, 2006). 

All sensors on the multi-probe meter were calibrated daily. 

Measured dissolved oxygen, temperature, pH, and specific 

conductance values were recorded at 5-minute (min) intervals, 

and when these values remained stable for a minimum of 

30 min, samples for laboratory analyses then were collected. 

Field measurements and instrument calibrations were 

recorded on field record sheets and electronically on field 

laptop computers using the Personal Computer Field Form 

(PCFF) program. Analytical service requests for the NWQL 

were generated by PCFF, whereas analytical service requests 

for non-NWQL analysis were entered into laboratory-specific 

spreadsheets. Information from PCFF was uploaded directly 

into the USGS NWIS database at the end of every week of 

sample collection. 

Prior to sample collection, polyethylene sample bottles 

were pre-rinsed three times with deionized water and then 

once with native sample water before sample collection. 

Samples requiring acidification were acidified to a pH of 

between 2 and 1 with the appropriate acids by using ampoules 

of certified, traceable concentrated acids obtained from the 

NWQL.

VOC samples were collected in three 40-milliliter (mL) 

sample vials that were purged with three vial volumes of 

unfiltered groundwater before bottom-filling to eliminate 

atmospheric contamination. One to one (1:1) hydrochloric 

acid to water (HCl/H2

O) solution was added as a preservative 

to the VOC samples. Tritium samples were collected by 

bottom-filling one 1-L polyethylene bottle and one 1-L glass 

bottle with unfiltered groundwater, after first overfilling the 

bottles with three volumes of unfiltered groundwater. Samples 

for analysis of stable isotopes of hydrogen and oxygen in 

water were collected in 60-mL clear glass bottles filled with 

unfiltered groundwater, sealed with a conical cap, and secured 

with electrical tape to prevent leakage and evaporation. 
64 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Pesticides and pesticide degradate samples were collected in 

1-L baked amber glass bottles. Samples were filtered through 

a 0.7-micrometer (μm) nominal pore-size glass fiber filter 

during collection.

Groundwater samples for analysis of trace elements, 

major and minor ions, silica, and TDS required filling one 

250-mL polyethylene bottle with unfiltered groundwater 

and one 500-mL and one 250-mL polyethylene bottle with 

filtered groundwater (Wilde and others, 2004). Filtration was 

done by using a 0.45-μm pore-size PALL® unvented capsule 

filter that was pre-rinsed with 2 L of deionized water and 

then rinsed with 1 L of groundwater prior to sampling. The 

250-mL filtered sample then was preserved with 7.5-N nitric 

acid. Samples for analyses of nutrients were filtered into 

125-mL brown polyethylene bottles. Samples for analyses 

of arsenic and iron species were filtered into 250-mL 

polyethylene bottles that were covered with tape to prevent 

light exposure and preserved with 6-N hydrochloric acid. 

Samples for analyses of isotopic ratios of dissolved strontium 

were filtered into 250-mL polyethylene bottles and secured 

with electrical tape to prevent leakage and evaporation. 

Samples for stable isotopes of carbon in dissolved inorganic 

carbon and carbon-14 abundance were filtered and bottomfilled into 500-mL glass bottles that first were overfilled with 

three bottle volumes of filtered groundwater. These samples 

had no headspace and were sealed with conical caps to avoid 

atmospheric contamination. Samples for field alkalinity 

titrations were collected by filtering groundwater into 500-mL 

polyethylene bottles.

For the collection of groundwater samples for analysis 

of radon-222, a stainless-steel and Teflon® valve assembly 

was attached to the sampling port at the wellhead (Wilde 

and others, 2004). The valve was closed partially to create 

back pressure, and a 10-mL groundwater sample was taken 

through a Teflon® septum on the valve assembly by using a 

glass syringe affixed with a stainless-steel needle. The sample 

was then injected into a 25-mL vial partially filled with a 

scintillation mixture (mineral oil) and shaken. The vial was 

placed in an insulated cardboard tube to protect the sample 

during shipping. 

Samples for analyses of dissolved noble gases were 

collected in 3⁄8-inch-diameter copper tubes by using reinforced 

nylon tubing connected to the hose bib at the wellhead. 

Groundwater was flushed through the tubing to dislodge any 

bubbles before the flow was restricted with a back pressure 

valve. Clamps on either side of the copper tube then were 

tightened, trapping a sample of groundwater for analyses of 

dissolved noble gases (Weiss, 1968). 

Samples for analysis of the presence or absence of 

microbial indicators were collected at the wellhead using the 

IDEXX Colilert® test kit (Standard Method 9223; American 

Public Health Association, 1998). Prior to the collection of 

samples, the sampling port was sterilized with isopropyl 

alcohol and then was flamed or left to air dry. Groundwater 

was run through the sampling port for at least 2 minutes to 

remove any traces of the sterilizing agent. A 100-mL IDEXX 

Colilert® sterile sample bottle containing sodium thiosulfate 

(to neutralize chlorine when present) was filled directly from 

the sampling port. After a reagent was added, the sample 

bottle was inverted gently to mix the reagent with the sample. 

The sample was incubated for 24 hours at 35 oC ± 0.5 oC. 

Sample results were viewed against a comparator and 

interpreted as follows: if the sample was (1) less yellow than 

the comparator, then the presence of total coliform and E. coli

were not detected; (2) more yellow than or the same as the 

comparator, then the presence of total coliform was detected; 

(3) more yellow and more fluorescent than or the same as the 

comparator, then the presence of E. coli was detected. 

Field alkalinity was measured in the mobile laboratory 

at 25 percent of the field sites. Field alkalinity was measured 

in filtered groundwater samples by Gran’s titration method 

(Gran, 1952). Titration data were entered directly into PCFF, 

and the concentrations of bicarbonate (HCO3

–

) and carbonate 

(CO3

2–) automatically were calculated from the titration data 

by using the advanced speciation method (http://or.water.

usgs.gov/alk/methods.html) with pK1 = 6.35, pK2 = 10.33, 

and pKW = 14. Concentrations of HCO3

–

 and CO3

2– also were 

calculated for all field sites from the laboratory alkalinity and 

laboratory pH measurements. 

Temperature-sensitive samples were stored on ice prior 

to and during daily shipping to the various laboratories. The 

non-temperature- or non-time-sensitive samples for analyses 

of tritium, stable isotopes of hydrogen and oxygen in water, 

isotopic ratios of dissolved strontium, and dissolved noble 

gases were shipped monthly. Temperature- or time-sensitive 

samples for analyses of VOCs, pesticides and pesticide 

degradates, perchlorate, trace elements, nutrients, major 

and minor ions, silica, and TDS were shipped daily. The 

temperature-sensitive samples for analyses of arsenic and iron 

species were stored on ice and shipped weekly. Samples for 

analyses of stable isotopes of carbon in dissolved inorganic 

carbon and carbon-14 abundance were stored on ice, archived 

in a laboratory refrigerator, and shipped after results for 

alkalinity were received from the NWQL.

Nine laboratories performed chemical analyses for 

this study (table A1), although most of the analyses were 

performed at the NWQL or by laboratories contracted by the 

NWQL. The NWQL maintains a rigorous QA program (Pirkey 

and Glodt, 1998; Maloney, 2005). Laboratory QC samples, 

including method blanks, continuing calibration verification 

standards, standard reference samples, reagent spikes, external 

certified reference materials, and external blind proficiency 

samples, are analyzed regularly. Method detection limits 

are tested continuously, and laboratory reporting levels are 

updated accordingly. The NWQL maintains the National 

Environmental Laboratory Accreditation Program (NELAP) 

and other certifications. In addition, the USGS Branch of 

Quality Systems (BQS) maintains independent oversight of 

QA at the NWQL and laboratories contracted by the NWQL. 

The BQS also runs the National Field Quality Assurance 

Program (NFQA) that includes annual testing of all USGS 

field personnel for proficiency in making field water-quality 
Appendix 65

measurements and evaluation of equipment used to collect 

these measurements (http://qadata.cr.usgs.gov/nfqa/). Results 

for analyses made at the NWQL or by laboratories contracted 

by the NWQL are uploaded directly into the USGS NWIS 

database. Results of analyses made at other laboratories are 

compiled in a project database and uploaded from there into 

the USGS NWIS database. Some laboratory QC data are 

stored in the USGS NWIS database also.

Data Reporting

Laboratory Reporting Conventions

The USGS NWQL uses different conventions for 

reporting results for organic, inorganic, and radioactive 

constituents. For organic constituents (VOCs and pesticides), 

an LRL and a long-term method detection level (LT-MDL) are 

used as thresholds for reporting analytical results. The LRL is 

set to minimize the reporting of false negatives (not detecting 

a compound when it actually is present in a sample) to less 

than 1 percent (Childress and others, 1999). The LRL usually 

is set at two times the LT-MDL. The LT-MDL is derived from 

the standard deviation of at least 24 method detection level 

(MDL) determinations made over an extended period of time. 

The MDL is the minimum concentration of a substance that 

can be measured and reported with 99-percent confidence that 

the concentration is greater than zero (at the MDL there is less 

than a 1-percent chance of a false positive) (Childress and 

others, 1999; U.S. Environmental Protection Agency, 2002). 

The USGS NWQL updates LRL and LT-MDL 

values regularly, and the values listed in this report were 

in effect during the period that analyses were made for 

groundwater samples from the KLAM study unit (October to 

December 2010). Concentrations less than the LRL and the 

LT-MDL are reported as non-detections with a dash (—) in the 

data tables.

Concentrations between the LRL and the LT-MDL are 

reported as having a higher degree of uncertainty (coded 

by the letter “E” preceding the values in the tables and 

text). For methods that utilize gas chromatography or highperformance liquid chromatography (HPLC) with mass 

spectrometry detection, such as those methods used to analyze 

VOCs and pesticides, detections less than the LT-MDL have 

high certainty of presence, but the precise concentration is 

uncertain. These values are also E-coded. E-coded values also 

may result from detections outside the range of calibration 

standards from detections that did not meet all laboratory QC 

criteria and from samples that were diluted prior to analysis 

(Childress and others, 1999).

Some constituents in this study are reported relative to 

minimum reporting levels (MRLs) or method uncertainties 

(MUs). The MRL is the smallest measurable concentration 

of a constituent that may be reliably reported using a given 

analytical method (Timme, 1995). The MU generally indicates 

the precision of a particular analytical measurement; it gives a 

range of values wherein the true value will likely be found. 

Results for most constituents are given by using the 

LRL, LT-MDL, MDL, or MRL values provided by the 

analyzing laboratories. Results for some organic and inorganic 

constituents are presented using SRLs derived from assessing 

results from QC samples associated with groundwater samples 

collected as part of the GAMA-PBP [see the appendix 

section titled “Methods of Determining Study Reporting 

Levels (SRLs)”]. The SRLs are raised reporting levels with 

concentrations greater than the concentrations of the reporting 

level used by the laboratory.

The methods used for analysis of the radiochemical 

constituents (tritium, radon-222, and gross alpha and gross 

beta radioactivity) measure activities by counting techniques 

(table A1). Activity often is used instead of concentration for 

reporting the presence of radioactive constituents. Activity 

of these constituents in groundwater is measured in units of 

picocuries per liter (pCi/L), and 1 pCi/L is approximately 

equal to two atoms decaying per minute. The number of atoms 

decaying is equal to the number of alpha or beta particles 

emitted. 

The reporting limits for the radiochemical constituents 

are based on sample-specific critical levels (ssLC) (McCurdy 

and others, 2008). The critical level is analogous to the 

LT-MDL used for reporting analytical results for organic and 

non-radioactive inorganic constituents. Here, the critical level 

is defined as the minimum measured activity that indicates 

a positive detection of the radionuclide in the sample with 

less than a 5-percent probability of a false positive detection. 

Sample-specific critical levels are used for radioactive 

measurements because the critical level is sensitive to sample 

size and sample yield during analytical processing and is 

dependent on instrument background, on counting times for 

the sample and background, and on the characteristics of the 

instrument being used and the nuclide being measured. An 

ssLC is calculated for each sample, and the measured activity 

in the sample is compared to the ssLC associated with that 

sample. Measured activities less than the ssLC are reported as 

non-detections with a dash (—) in the data tables.

The analytical uncertainties associated with measurement 

of activities also are sensitive to sample-specific parameters, 

including sample size, sample yield during analytical 

processing, and time elapsed between sample collection and 

various steps in the analytical procedure, as well as parameters 

associated with the instrumentation. Therefore, measured 

activities of radioactive constituents are reported with samplespecific combined standard uncertainties (CSUs). The CSU is 

reported at the 68-percent confidence level (1-sigma).

Stable isotopic compositions of hydrogen, oxygen, and 

carbon are reported as relative isotope ratios in units of per mil 

using the standard delta notation (Coplen and others, 2002):

δi sample

reference

E

R

R = −

















1 1× 000, per mil , (A1)
66 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

where i is the atomic mass of the heavier isotope of 

the element;

E is the element (H for hydrogen, O for oxygen, 

and C for carbon);

Rsample is the ratio of the abundance of the heavier 

isotope of the element (2H, 18O, 13C) to the 

lighter isotope of the element (1H, 16O, 12C) 

in the sample; and

Rreference is the ratio of the abundance of the heavier 

isotope of the element to the lighter isotope 

of the element in the reference material.

The reference material for oxygen and hydrogen is 

Vienna Standard Mean Ocean Water (VSMOW), which is 

assigned δ18O and δ2H values of 0 per mil (note than δ2H is 

sometimes written as δD because the common name of the 

heavier isotope of hydrogen, hydrogen-2, is deuterium). The 

reference material for carbon is Vienna Pee Dee Belemnite 

(VPDB), which is assigned a δ13C value of 0 per mil. Positive 

values indicate enrichment of the heavier isotope, and negative 

values indicate depletion of the heavier isotope, compared to 

the ratios observed in the standard reference material. Isotopic 

ratios of strontium in water are presented as the abundance of 

atoms of the heavier isotope (87Sr) to the lighter isotope (86Sr) 

of the element.

Constituents Determined by Multiple Methods or 

Laboratories

Six constituents were measured by more than 

one analytical method or by more than one laboratory 

(table A2). The preferred methods for these constituents 

were selected on the basis of the procedure recommended 

by the NWQL (http://wwwnwql.cr.usgs.gov/dyn.

shtml?Preferred_method_selection_procedure). 

The water-quality indicators—alkalinity, pH, and specific 

conductance—were measured in the field and at the NWQL. 

The field measurements are the preferred method for all 

three constituents; however, both measurements are reported 

(table 4). Field values are generally preferred because field 

conditions are considered more representative of groundwater 

conditions (Hem, 1985).

For total arsenic and total iron concentrations, the 

approved method, Schedule 1948 (table 3G), used by the 

NWQL is preferred over the research methods used by the 

USGS NRP-TML (table 3D); however, both measurements 

are reported (tables 7 and 10). The concentrations of arsenic 

and iron measured by the USGS NRP-TML only are used to 

calculate ratios of redox species (table 10).

For example,

Fe( ) III = − Fe( ) T Fe I( )I , (A2)

where

Fe(T) is the total iron concentration (measured),

Fe(II) is the concentration of ferrous iron 

(measured), and

Fe(III) is the concentration of ferric iron (calculated).

Tritium also was measured at two laboratories: LLNL 

and USGS Stable Isotope and Tritium Laboratory, Menlo 

Park, California (SITL) (table 3H). There was no preferred 

laboratory for the reporting of tritium, and only tritium data 

from the SITL were available for reporting at the time of this 

publication (table 12). 

Quality-Assurance and Quality-Control Methods 

and Results

The purpose of QA/QC is to identify which data best 

represent groundwater conditions and which may have been 

affected by contamination or bias during sample collection, 

processing, storage, transportation, and (or) laboratory 

analyses. Four types of QC measurements were evaluated 

in this study: (1) blank samples were collected to assess 

positive bias as a result of contamination during sample 

handling or analysis, (2) replicate samples were collected 

to assess variability, (3) matrix-spike tests were done to 

assess positive or negative bias for organic constituents, and 

(4) surrogate compounds were added to samples analyzed for 

organic constituents to assess potential bias from laboratory 

analytical methods. Results that were found to have significant 

contamination bias, on the basis of the QC data collected from 

this and previous studies, were flagged with an appropriate 

remark code (described in subsequent sections) and rejected 

from subsequent use, including calculations of detection 

frequency. 

Field Blank Samples

The primary purposes of collecting field blank samples 

are to evaluate potential contamination of samples with 

compounds of interest during sample handling or analysis and 

to identify and mitigate the sources of sample contamination 

(if present).

Methods of Field Blank Sample Collection and Analysis

Field blank samples were collected by using blank water 

certified by the NWQL to contain less than the reporting levels 

for selected constituents investigated in the study (http://

wwwnwql.cr.usgs.gov/USGS/OBW/obw.html). Nitrogenpurged, organic-free water was used to process blanks 

analyzed for organic constituents, and inorganic-free water 

was used to process blanks for inorganic constituents. 
Appendix 67

Field blank samples were collected to assess whether 

contamination of samples was introduced during collection, 

processing, transport, and analysis. To collect field blanks, 

blank water either was pumped or poured through the same 

sampling equipment used to collect groundwater samples, then 

processed and transported by using the same protocols used 

for the groundwater samples. Typically, 12 L of blank water 

were pumped or poured through the sampling equipment 

before each field blank was collected. Field blanks were 

analyzed for VOCs, pesticides and pesticide degradates, 

perchlorate, trace elements, nutrients, major and minor ions, 

silica, TDS, arsenic and iron species, and microbial indicators. 

Field blank samples were not collected for radon and 

gross alpha and gross beta particle activities because the 

laboratory determines an ssLC value for each sample. The 

ssLC is the minimum measured value that indicates a non-zero 

amount of the radionuclide in the sample. Stated another way, 

it is the amount of radionuclide that is statistically significantly 

greater than the amount in a blank. In addition, blanks were 

not collected for tritium or dissolved noble gases. Tritium 

and dissolved noble gases are in the atmosphere and would 

dissolve into any solution used in collecting a blank, making 

it impractical to collect a blank for these analytes. Isotopic 

ratios of hydrogen, oxygen, boron, strontium, and carbon are 

an intrinsic property of any of these elements; therefore, the 

concept of a blank does not apply to these ratios.

Methods of Determining Study Reporting Levels (SRLs)

The SRLs for selected VOCs were defined by Fram and 

others (2012) on the basis of the assessment of results from 

field blank samples, source-solution blank samples, laboratory 

instrument blank samples, and groundwater samples from 

the first 32 GAMA-PBP study units (May 2004 through 

September 2010). SRLs were established for those VOCs 

that had evidence of potential contamination due to field or 

laboratory processes. Detections of VOCs in groundwater 

samples at concentrations less than the SRLs were reported 

with a ≤ symbol preceding the measured value from the 

laboratory and considered non-detections.

The SRLs for trace elements were defined by Olsen and 

others (2010) on the basis of statistical assessment of results 

from the field blank samples from the first 20 GAMA-PBP 

study units (May 2004 through January 2008). The assessment 

used order statistics and binomial probabilities to construct 

an upper confidence limit (Hahn and Meeker, 1991) for the 

maximum concentration of constituents possibly introduced 

while groundwater samples were collected, processed, 

transported, and analyzed. Detections of trace elements having 

concentrations less than or equal to the SRLs were reported 

with a ≤ symbol preceding the measured value from the 

laboratory to indicate that the true value may be less than or 

equal to the reported value (including the possibility of being a 

non-detection). 

The SRLs for two other constituents collected for the 

KLAM study unit (cobalt and manganese) were defined as 

equal to the highest concentration measured in the field blank 

samples. Detections of constituents in groundwater samples at 

concentrations less than or equal to the SRLs defined by the 

field blank samples were reported with a ≤ symbol preceding 

the measured value from the laboratory (for inorganic 

constituents) as described by Olsen and others (2010). 

In the USGS NWIS database, data affected by SRLs are 

accompanied with the following comment: “Result is < or = 

reported value, based on QC data.”

Detections in Field Blank Samples and Application 

of SRLs

Table A3 presents a summary of detections in the field 

blank samples and the SRLs applied for the KLAM study unit. 

Field blanks samples were collected at 13 percent of the sites 

sampled in the KLAM study unit. 

Five field blank samples were collected in the KLAM 

study unit for the analysis of VOCs. 1,2,4-Trimethylbenzene 

was detected in two field blank samples. Toluene and 

tetrahydrofuran have SRLs defined by Fram and others (2012). 

A summary of the VOC field blank sample detections and (or) 

concentration ranges and SRL applications is listed here:

• 1,2,4-Trimethylbenzene was detected in two field 

blank samples at concentrations of 0.096 μg/L and 

0.024 μg/L. 1,2,4-Trimethylbenzene has an SRL of 

0.56 μg/L as defined by Fram and others (2012), 

and 31 groundwater samples had detections with 

concentrations less than the SRL (table 5, footnote 1). 

• Toluene has an SRL of 0.69 μg/L as defined by Fram 

and others (2012), and one groundwater sample had a 

detected concentration less than the SRL (table 5). 

• Tetrahydrofuran has an SRL defined by Fram and 

others (2012) that consists of coding all detected 

concentrations in groundwater as “reviewed and 

rejected” in the USGS NWIS database. This is 

equivalent to saying no data are available for 

tetrahydrofuran for two groundwater samples in the 

KLAM study unit (table 5, footnote 1). 

Five field blank samples were collected in the KLAM 

study unit for the analysis of trace elements. Seven trace 

elements (cobalt, copper, iron, lead, manganese, molybdenum, 

and tungsten) were detected in one or more of the field 

blank samples collected. An additional three trace elements 

(chromium, nickel, and zinc) were detected in groundwater 

samples at concentrations less than or equal to the SRLs 

defined by Olsen and others (2010). A summary of the trace 

element field blank sample detections and (or) concentration 

ranges and SRL applications is listed here:

• Cobalt was detected in four field blank samples, at 

concentrations ranging from 0.04 μg/L to 0.23 μg/L 

(table A3). Cobalt has an SRL of 0.23 μg/L as defined 

by the blank results, and 28 groundwater samples 
68 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

had detections with concentrations less than the SRL 

(table 7). 

• Copper was detected in one field blank sample at a 

concentration of 1.0 μg/L (table A3). Copper has 

an SRL of 1.7 μg/L as defined by Olsen and others 

(2010), and 16 groundwater samples had detections 

with concentrations less than the SRL (table 7). 

• Iron was detected in one field blank sample at a 

concentration of 4.9 μg/L (table A3). Iron has an SRL 

of 6.0 μg/L as defined by Olsen and others (2010), 

and three groundwater samples had detections with 

concentrations less than the SRL (table 7). 

• Lead was detected in two field blank samples at 

concentrations of 0.12 μg/L and 0.28 μg/L (table A3). 

Lead has an SRL of 0.65 μg/L as defined by Olsen 

and others (2010), and 28 groundwater samples had 

detections with concentrations less than the SRL 

(table 7). 

• Manganese was detected in two field blank samples at 

concentrations of 0.16 μg/L and 0.36 μg/L (table A3). 

Manganese has an SRL of 0.36 μg/L as defined by 

the blank results, and seven groundwater samples 

had detections with concentrations less than the SRL 

(table 7). 

• Molybdenum was detected in one field blank sample at 

a concentration of 0.02 μg/L (table A3). Molybdenum 

was not detected in groundwater samples at 

concentrations ≤ 0.02 μg/L; therefore, application of an 

SRL was not necessary. 

• Tungsten was detected in one field blank sample at a 

concentration of 0.02 μg/L (table A3). Tungsten has 

an SRL of 0.11 μg/L as defined by Olsen and others 

(2010), and 11 groundwater samples had detections 

with concentrations less than the SRL (table 7). 

• Chromium has an SRL of 0.42 μg/L as defined by 

Olsen and others (2010), and 17 groundwater samples 

had detections with concentrations less than the SRL 

(table 7). 

• Nickel has an SRL of 0.36 μg/L as defined by Olsen 

and others (2010), and 11 groundwater samples had 

detections with concentrations less than the SRL 

(table 7). 

• Zinc has an SRL of 4.8 μg/L as defined by Olsen 

and others (2010), and 15 groundwater samples had 

detections with concentrations less than the SRL 

(table 7).

Four field blank samples were collected in the KLAM 

study unit for the analysis of the major and minor ions, silica, 

and TDS. Silica (as SiO2

) was detected in one field blank at 

a concentration of 0.030 mg/L (table A3). Silica (as SiO2) 

was not detected in groundwater samples at concentrations 

≤ 0.030 mg/L (table 9); therefore, application of an SRL was 

not necessary. Pesticides were not detected in field blank 

samples. 

Replicate Sample Pairs

Sequential replicate sample pairs were collected to assess 

the precision of the water-quality data. Estimates of data 

precision are needed to assess whether differences between 

concentrations in samples are because of differences in 

groundwater quality or because of variability that may result 

from collecting, processing, and analyzing the samples. 

Methods of Assessment of Replicate Sample Pairs

Three methods for measuring replicate pair variability 

were used to assess precision over the range of measured 

concentrations in groundwater samples. The variability 

between results in the pairs of replicate samples was 

represented by the absolute standard deviation (SD) for low 

concentrations and by relative standard deviation (RSD) for 

high concentrations (Anderson, 1987; Mueller and Titus, 

2005). The RSD is defined as the SD divided by the mean 

concentration for each replicate pair of samples expressed as 

a percentage. The boundary between concentrations for each 

metric was defined as five times (×) the reporting level (RL) 

for each constituent: pairs with mean concentrations ≤ 5×RL 

used the SD, and pairs with mean concentrations > 5×RL used 

the RSD. As discussed in the section “Laboratory Reporting 

Conventions,” the RL for most constituents was an LRL or 

LT-MDL, and some constituents are reported with an SRL, 

MDL, or MRL. 

Replicate pairs of analyses for all constituents except for 

radioactive constituents were evaluated as follows. 

• If both values were reported as detections, the SD or 

RSD was calculated. Acceptable variability is defined 

as an SD of < 1⁄2 RL or an RSD of < 10 percent. For 

comparison, an RSD of 10 percent is equivalent to a 

relative percent difference (RPD) of 14 percent.

• If both values were reported as non-detections, the 

variability was set to zero by definition. 

• If one value was reported as a non-detection, and the 

other value was reported as a detection < RL, then a 

value of zero was substituted for the non-detection, 

and the SD was calculated. Zero was selected as 

substitution value because substituting zero for the 

non-detection yields the maximum possible value for 

the SD for the replicate pair.

• If one value for a sample pair was reported as a 

non-detection and the other value was flagged with 

a ≤ symbol, or if both values were flagged with a ≤ 

symbol, the SD was not calculated because the values 

may be analytically identical. The ≤ symbol indicates 
Appendix 69

that the value is a maximum potential concentration 

and the true concentration could be < RL for the other 

sample in the pair.

• If one value was reported as a non-detection and the 

other value was reported as a detection > RL, the 

variability for the pair was considered unacceptable.

Replicate pairs for analyses of radioactive constituents 

were evaluated by using the following equation (Parr and 

Porterfield, 1997; McCurdy and others, 2008) to calculate the 

normalized absolute difference (NAD):

NAD x y

CSU C X y SU

≤ −

+2 2 , (A3)

where x = activities of a radiochemical constituent in the 

groundwater sample,

y = activities of the same radiochemical 

constituent in the replicate sample,

CSUx = combined standard uncertainty of x at the 1σ 

confidence level, and

CSUy = combined standard uncertainty of y at the 1σ 

confidence level.

Values < 1.65 for the NAD correspond to a significance level 

(α) of 5 percent (α = 0.05), indicating differences that are 

acceptably small and not statistically significant.

Variability in Replicate Sample Pairs

If results from replicate sample pairs indicate that 

variability is unacceptable for a constituent, then this 

greater variability must be considered when interpreting 

the data. If measured concentrations are slightly greater 

than a water-quality benchmark, then actual concentrations 

could be less than that benchmark. Similarly, if measured 

concentrations are less than a water-quality benchmark, then 

actual concentrations could be greater than a benchmark. If a 

constituent has high variability in replicate sample pairs, then 

a larger difference between concentrations measured in two 

samples is required to conclude that the two samples have 

significantly different concentrations. 

Tables A4A–D summarize the results of replicate pair 

analyses for groundwater samples collected in the KLAM 

study unit. Replicate sample pairs were collected for 

13 percent of the samples collected. 

Five replicate pairs of samples were analyzed for 

VOCs, and all pairs were composed of two values reported 

as non-detections with the exception of one replicate pair for 

chloroform. The replicate pair yielded two values reported as 

detections, and the replicate pair analysis resulted in an SD 

within acceptable precision. 

Six replicate pairs of samples were analyzed for pesticide 

and pesticide degradate compounds, and all pairs were 

composed of two values reported as non-detections with the 

exception of one replicate pair analyzed for simazine. The 

replicate pair yielded two values reported as detections, and 

the replicate pair analysis resulted in an SD within acceptable 

precision. 

Five replicate pairs of samples were analyzed for 

inorganic constituents. All replicate pairs were either 

composed of two values reported as non-detections or two 

values reported as detections. The analyses for all replicate 

pairs reported as detections resulted in SDs and RSDs within 

acceptable variability.

Five replicate pairs of samples were analyzed for uranium 

and other radioactive constituents. All replicate pairs yielded 

statistically similar results (p ≤ 0.05), with the exception 

of one replicate pair for gross alpha radioactivity (72-hour 

count). 

Five replicate pairs of samples were analyzed for 

microbial indicators, and all pairs were composed of two 

values reported as non-detections with the exception of three 

replicate pairs of total coliform. These replicate pairs each 

yielded one value reported as M (presence verified but not 

quantified) and one value reported as a non-detection. 

Groundwater data were not flagged in any way on the 

basis of the results of replicate sample pair analyses.

Matrix-Spike Samples

Addition of a known concentration of a constituent 

(spike) to a replicate groundwater sample enables the 

laboratory to determine the effect of the matrix, in this case 

groundwater, on the analytical technique used to measure 

the constituent in the sample. The known compounds added 

in matrix-spike samples are the same as those analyzed in 

the groundwater samples. This enables an analysis of matrix 

interferences on a compound-by-compound basis. As part 

of the GAMA Program, matrix spikes were added by the 

laboratories performing the analysis rather than in the field. 

Low matrix-spike recoveries may indicate that measured 

concentrations in some groundwater samples could be lower 

than actual concentrations—including the possibility that 

some samples containing low concentrations of a constituent 

may be reported as having non-detections for a constituent. 

High matrix-spike recoveries may indicate that measured 

concentrations in some groundwater samples could be greater 

than actual concentrations. 

The GAMA-PBP defined the data-quality objective 

range for acceptable median matrix-spike recoveries as 70 

to 130 percent. Only constituents with median matrix-spike 

recoveries outside of this range were flagged as having 

unacceptable recoveries. Matrix spikes were performed for 

VOCs and pesticides and pesticide degradates because the 

analytical methods for these constituents may be susceptible to 

matrix interferences. 
70 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Matrix-Spike Sample Recoveries

Tables A5A, B present a summary of matrix-spike sample 

recoveries for the KLAM study unit. Spiked samples were 

collected at 13 percent of the sites sampled. 

Five groundwater samples were spiked with VOCs 

to calculate matrix-spike recoveries. Median matrix-spike 

recoveries for all 85 spike compounds were between 70 and 

130 percent (table A5A). 

Five groundwater samples were spiked with pesticide 

and pesticide degradate compounds to calculate matrixspike recoveries. Median matrix-spike recoveries for 50 of 

the 63 spike compounds were between 70 and 130 percent. 

Seventeen of the spike compounds had median matrix-spike 

recoveries < 70 percent. All four pesticide and pesticide 

degradate compounds detected in groundwater samples had 

median matrix-spike recoveries within the acceptable range 

(table A5B). 

Data for groundwater samples were not flagged on the 

basis of the results from the matrix-spike recovery analyses.

Surrogate Compounds

Surrogate compounds are added to groundwater samples 

in the laboratory prior to analysis to evaluate the recovery of 

chemically similar constituents. Surrogate compounds were 

added in the laboratory to all groundwater and QC samples 

analyzed by the NWQL for VOCs and pesticides and pesticide 

degradates. Surrogates are used to identify general problems 

that may arise during laboratory sample analysis that could 

affect the analysis results for many compounds in that sample. 

Potential problems include changes in instrument response 

and matrix interferences (such as high dissolved organic 

carbon concentrations) that can produce a positive or negative 

bias. A 70 to 130 percent recovery of surrogates, in general, 

is considered acceptable; values outside this range indicate 

possible problems with the processing and analysis of samples 

(Connor and others, 1998; Sandstrom and others, 2001).

Surrogate Compound Recoveries

Table A6 presents a summary of the surrogate compound 

recoveries for the KLAM study unit. The table lists the 

surrogate compound, the analytical schedule for which it was 

applied, the number of analyses for blank and groundwater 

samples, the number of median surrogate recoveries 

< 70 percent, and the number of median surrogate recoveries 

> 130 percent for each matrix (blank and groundwater 

samples). Blank and groundwater samples were considered 

separately to assess whether or not the matrices present in 

groundwater samples affected surrogate recoveries. 

Most surrogate compound recoveries for the blank 

and groundwater samples were within the acceptable range 

of 70 to 130 percent. In total, 92 percent of the blank and 

93 percent of the groundwater sample surrogate recoveries for 

VOC analyses were within the acceptable range. In addition, 

92 percent of the blank and 94 percent of the groundwater 

sample surrogate recoveries for pesticide and pesticide 

degradate analyses were within the acceptable range. There 

were no significant differences between VOC and pesticide 

and pesticide degradate surrogate recoveries in blank and 

groundwater samples (Wilcoxon rank sum test, p < 0.05).

Data for groundwater samples were not flagged on the 

basis of the results of surrogate compound recovery analyses.

Other Quality-Control Results

Three laboratory QC matters arose during the analysis 

of samples collected for KLAM study unit: (1) perchlorate 

data that did not meet QC standards as required by the 

GAMA Program, (2) holding-time violations for the results 

of radioactive constituent data, and (3) internal laboratory QC 

tests indicating bias on the results of trace element data.

Perchlorate

Groundwater samples were analyzed for perchlorate 

at Weck using a laboratory method with an MRL of 

0.10 μg/L. Samples from three of the KLAM grid sites had 

reported detections of perchlorate at concentrations greater 

than the MCL-CA of 6 μg/L. These three grid sites were 

located in the southern part of the KLAM study unit. The 

occurrence of groundwater having perchlorate concentrations 

greater than the MCL-CA in that area was unusual because 

the area had no reported sites of perchlorate contamination 

in groundwater or sites where perchlorate was manufactured 

or used extensively (U.S. Environmental Protection Agency, 

2005b; California Department of Toxic Substances Control, 

2007; California State Water Resources Control Board, 

2009), and the area around the sites is largely undeveloped, 

forested land with no agricultural crops. Concentrations of 

perchlorate > 1 μg/L in groundwater are unlikely to represent 

natural conditions and thus generally indicate presence of 

anthropogenic sources of perchlorate (Fram and Belitz, 2011). 

These three grid sites were re-sampled in November 2011, 

approximately 11 months after the initial KLAM study unit 

sampling took place. Perchlorate was not detected in the 

second set of groundwater samples. The groundwater at all 

three sites was oxic during both sampling events, thus, it is 

unlikely that the absence of perchlorate in the second sampling 

event was due to microbial reduction of perchlorate. The 

fact that perchlorate was not detected in the second set of 

groundwater samples from the three grid sites casts doubt on 

the validity of the detections of perchlorate at concentrations 

> 6 μg/L in the first set of groundwater samples from those 

three grid sites.

In addition, the detection frequency of perchlorate in the 

KLAM study unit as a whole was unexpectedly high, given 

the absence of indicators of potential anthropogenic sources of 

perchlorate. The observed detection frequency of perchlorate 

at concentrations > MRL (0.10 μg/L) was 65 percent. The 

study unit has a relatively wet climate; thus, the predicted 

probability of detecting perchlorate under natural conditions 
Appendix 71

is relatively low. The predicted probability of detecting 

perchlorate at concentrations > 0.10 μg/L under natural 

conditions for the average aridity index of all of the KLAM 

sampling sites (aridity index = 1.20) is 22 percent (Fram and 

Belitz, 2011).

Analysis of the QC samples (blank samples, replicate 

sample pairs, and matrix spikes) collected in the KLAM study 

unit did not reveal any obvious QC problems. Perchlorate was 

not detected in any of the five field blank samples collected 

during the KLAM study. Five replicate sample pairs were 

within acceptable precision; four of the five replicate sample 

pairs had two values reported as non-detections, and the fifth 

replicate sample pair consisted of one non-detection and one 

detection (with a concentration of 0.11 μg/L). One matrixspike recovery was performed (at a spike level of 5 μg/L), 

and the recovery was within the acceptable range of 70 to 

130 percent (97 percent). 

Even though the results from QC samples collected for 

perchlorate by the GAMA Program for the KLAM study unit 

were acceptable, the puzzling results for the groundwater 

samples raised questions about the quality of the data for the 

groundwater samples. It is a very serious matter to report 

detections of anthropogenic constituents like perchlorate 

with concentrations greater than the MCL-CA (or MCL-US) 

in CDPH and non-CDPH sites; thus, the GAMA Program 

maintains high standards for confidence in the quality of 

datasets. The perchlorate data for the KLAM study unit did not 

meet those high standards, and therefore, the GAMA Program 

is not reporting those data.

Holding-Time Violations for Radioactive Constituents

Holding time refers to the time (in calendar days) from 

sample collection to analysis. A holding-time violation occurs 

when a sample is analyzed past the given holding time for 

a particular analysis. The remote sampling areas within the 

KLAM study unit did not allow for immediate shipment of 

a few groundwater samples for the analysis of gross alpha 

and beta radioactivity. This resulted in later arrival times at 

the laboratory; thus, the analyses were completed after the 

acceptable holding time. This is important to consider because 

a delay in the analysis may result in lower measured activities 

than what may have been present in the groundwater. 

The gross alpha and beta radioactivities reported are the 

amounts measured in the samples. Radioactive decay occurs 

between the time of sample collection and measurement; 

therefore, gross alpha and gross beta radioactivity change with 

time. Generally, gross alpha decreases during the first 10 days 

due to decay of unsupported members of the thorium-232 

decay series (in particular, Ra-224 and its progeny). Four 

groundwater samples were analyzed past the holding time 

for gross alpha and beta radioactivity (72-hour count). The 

results for these four groundwater samples are footnoted in 

table 13. If samples with gross alpha or beta radioactivity 

counts ranging from about one-half of the benchmark to the 

benchmark values were present in the sample, a late analysis 

could result in reported activities below the benchmark. None 

of the late groundwater samples in the KLAM study unit were 

in this category.

Laboratory Bias in Trace Element Analyses

Laboratory bias, as indicated from internal laboratory QC 

tests, was investigated to determine whether or not the KLAM 

study unit data were affected by laboratory procedures. The 

BQS operates the Inorganic Blind Sample Project (IBSP) to 

monitor and evaluate the quality of results for analyses of 

trace elements, nutrients, major and minor ions, silica, and 

TDS by the NWQL. The IBSP submits standard reference 

samples consisting of natural water samples spiked with 

known concentrations of the inorganic constituents (Farrar and 

Long, 1997). The IBSP data are readily available on the BQS 

website, and the BQS issues monthly summaries of the results, 

reporting the amount of bias observed in the results (http://bqs.

usgs.gov/IBSP/).

The BQS monthly summaries were examined for October 

through December 2010, the period of sample collection and 

analyses for the KLAM study unit. During this time, the BQS 

reported that two inorganic constituents showed evidence 

of bias: a negative bias for boron and a positive bias for 

cadmium. Examination of the results for the IBSP samples 

for these two constituents indicated that the analytical biases 

reported by the BQS were not significant. 

The IBSP samples for boron had concentrations ranging 

from 16 μg/L to 45 μg/L. The average difference between 

the measured and expected concentrations was –3 μg/L 

(standard deviation = 3 μg/L), and the average RPD between 

the measured and expected concentrations was –10 percent 

(standard deviation = 8 percent). Boron concentrations in 

samples collected from the KLAM study unit ranged from 

“non-detection” to 2,230 μg/L (table 7). Given that the NL-CA 

for boron is 1,000 μg/L, a concentration much higher than the 

maximum concentration in the IBSP sample, a negative bias 

of 10 percent (or 3 μg/L) does not affect the assessment of 

whether groundwater samples in the KLAM study unit have 

boron concentrations greater than or less than the NL-CA 

concentration. A determination of bias at low concentrations 

does not imply that there is equivalent bias at higher 

concentrations.

The IBSP samples for cadmium had concentrations 

ranging from 0.2 μg/L to 2.5 μg/L. The average difference 

between the measured and expected concentrations was 

0.06 μg/L (standard deviation = 0.07 μg/L), and the average 

RPD between the measured and expected concentrations was 

9 percent (standard deviation = 25 percent). The MCL-US 

for cadmium is 5 μg/L, thus the estimate of bias from the 

IBSP samples would be relevant for an assessment of whether 

or not groundwater samples have cadmium concentrations 

greater than or less than the MCL-US. However, the maximum 

concentration of cadmium in samples from the KLAM study 

unit was 0.076 μg/L (table 7); thus, a potential positive bias 

of 0.06 μg/L, or 8 percent, would not result in an inflated 

measured concentration value greater than the benchmark 

when the true concentration is less than the benchmark.
Table A1. Analytical methods used by the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) and contract laboratories. [Laboratory entity codes in the USGS National Water Information System (NWIS) for laboratories other than the USGS National Water Quality Laboratory (NWQL) are given inames. Abbreviations: UV, ultraviolet; USEPA, U.S. Environmental Protection Agency; VOC, volatile organic compound; NRP, USGS National Research Program] Analyte Analytical method Laboratory and analytical schedule 

Water-quality indicators Field parameters Calibrated field meters and test kits USGS field measurement U.S. Geological S

Organic constituents VOCs Purge and trap capillary gas chromatography/ mass spectrometry NWQL, Schedule 2020 Connor and other

Pesticides and pesticide degradates Solid-phase extraction and gas chromatography/ mass spectrometry NWQL, Schedule 2003 Zaugg and others

1996; Sandstroand others, 200

Constituent of special interest Perchlorate Liquid chromatography with mass spectrometry/ mass spectrometry (USEPA Method 331.0) Weck Laboratories, Inc. [Weck], City of Industry, California (CA-WECK), standard operating procedure ORG099.R01 U.S. Environmen

Inorganic constituents Major and minor ions and trace elements Atomic absorption spectrometry, colorimetry, ion-exchange chromatography, inductively- coupled plasma atomic emission spectrometry, and mass spectrometry NWQL, Schedule 1948 Fishman and Frie

man, 1993; McAmerican PublGarbarino and 

Nutrients Alkaline persulfate digestion, Kjedahl digestion NWQL, Schedule 2755 Fishman, 1993; PArsenic and iron species Various techniques of ultraviolet visible (UV- VIS) spectrophotometry and atomic absor- bance spectroscopy USGS NRP Trace Metal Laboratory [TML], Boulder, Colorado (USGSTMCO) Stookey, 1970; To 

and others, 200

Isotopic tracers Stable isotopes of hydrogen and oxygen in water Gaseous hydrogen and carbon dioxide–water equilibration and stable-isotope mass spec- trometry USGS Stable Isotope Laboratory, Reston, Vir- ginia (USGSSIVA), NWQL Schedule 1142 Epstein and Maye

1991; Coplen, 

Isotopic ratios of strontium in water Chemical separations and thermal-ionization mass spectrometry USGS NRP Metals Isotope Research Laboratory, Menlo Park, California (USGSMICA) Bullen and others

Stable isotopes of carbon in dissolved inorganic carbon and carbon-14 abundance Accelerator mass spectrometry Woods Hole Oceanographic Institution, National Ocean Sciences Accelerator Mass Spec- trometry Facility [NOSAMS], Woods Hole, Massachusetts (MA-WHAMS), NWQL Schedule 2255 Vogel and others, 

1990; McNichand Jones, 199Schneider and 
Analyte Analytical method Laboratory and analytical schedule 

Radioactivity and dissolved gases

Tritium Electrolytic enrichment-liquid scintillation USGS Stable Isotope and Tritium Laboratory 

[SITL], Menlo Park, California (USGSH3CA), NWQL Schedule 1565

Thatcher and othe

Radon-222 Liquid scintillation counting NWQL, Schedule 1369 American Society Gross alpha and gross beta radioactivity (72-hour 

and 30-day counts)

Alpha and beta activity counting (USEPA 

Method 900.0)

Eberline Analytical Services, Richmond, California (CA-EBERL), NWQL Schedule 1792 Kreiger and Whit

Dissolved noble gases, tritium, and helium 

isotope ratios

Helium-3 in-growth and mass spectrometry Lawrence Livermore National Laboratory 

[LLNL], Livermore, California (CA-LLNL)

Moran and others

Microbial constituents

Escherichia coli (E. coli) and total coliform IDEXX Colilert® test kit (Standard 

Method 9223)

USGS field measurement American Public 

Table A1. Analytical methods used by the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) and contract laboratories.—Co[Laboratory entity codes in the USGS National Water Information System (NWIS) for laboratories other than the USGS National Water Quality Laboratory (NWQL) are given inames. Abbreviations: UV, ultraviolet; USEPA, U.S. Environmental Protection Agency; VOC, volatile organic compound; NRP, USGS National Research Program]
74 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Table A2. Preferred analytical methods or laboratories for selected constituents in groundwater samples collected for the Klamath 

Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California, October to December 2010.

[Preferred analytical schedules/methods are selected on the basis of the procedure recommended by the NWQL (http://wwwnwql.cr.usgs.gov/dyn.

shtml?Preferred_method_selection_procedure). Abbreviations: USGS, U.S. Geological Survey; NWQL, USGS National Water Quality Laboratory, Denver, 

Colorado; NRP, USGS National Research Project; TML, USGS-NRP Trace Metal Laboratory, Boulder, Colorado; LLNL, Lawrence Livermore National 

Laboratory, Livermore, California; SITL, USGS Stable Isotope and Tritium Laboratory, Menlo Park, California; np, no preference]

Constituent 

(synonym or abbreviation)

Primary constituent 

classification

Analytical methods 

or laboratory

Preferred analytical 

method or laboratory

Results from both methods reported

pH Water-quality indicator field, Schedule 1948 (NWQL) field

Specific conductance Water-quality indicator field, Schedule 1948 (NWQL) field

Alkalinity Water-quality indicator field, Schedule 1948 (NWQL) field

Arsenic (total) Trace element Schedule 1948 (NWQL), TML Schedule 1948

Iron (total) Trace element Schedule 1948 (NWQL), TML Schedule 1948

Tritium Inorganic tracer SITL, LLNL np
Appendix 75

Table A3. Constituents detected in the field blank samples and the study reporting level (SRL) analysis for the Klamath Mountains 

(KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California, October to December 2010.

[Abbreviations: RL, reporting level; VOC, volatile organic compound; ≤, less than or equal to; μg/L, micrograms per liter; mg/L, milligrams per liter; nv, no 

value in category; —, not detected]

Constituent

Number of field blank 

detections / total number of 

field blank samples

RL

Concentration(s) 

detected in field blank 

sample(s)

SRL 1

Number of groundwater samples 

≤-coded / total number of 

groundwater detections

VOCs (μg/L)

1,2,4-Trimethylbenzene 2/4 0.032 0.096, 0.024 0.56 B 31/31

Tetrahydrofuran 0/4 1.4 — all data B 2/2

Toluene 0/4 0.018 — 0.69 B 1/2

Trace elements (μg/L)

Chromium 0/5 0.06 — 0.42 C 17/32

Cobalt 4/5 0.02 0.04, 0.06, 0.09, 0.23 0.23 A 28/29

Copper 1/5 0.5 1.0 1.7 C 16/28

Iron 1/5 3.2 4.9 6.0 C 3/28

Lead 2/5 0.015 0.12, 0.28 0.65 C 28/35

Manganese 2/5 0.13 0.16, 0.36 0.36 A 7/31

Molybdenum 1/5 0.014 0.02 nv 0/38

Nickel 0/5 0.09 — 0.36 C 11/34

Tungsten 1/5 0.01 0.02 0.11 C 11/17

Zinc 0/5 1.4 — 4.8 C 15/35

Major and minor ions, silica, and total dissolved solids (TDS) (mg/L)

Silica (as SiO2

) 1/4 0.029 0.030 nv 0/38

1

 SRLs were defined (A) by the highest concentration in field blank samples collected for the KLAM study unit, (B) by Fram and others (2012), and (C) by 

Olsen and others (2010).
76 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Table A4A. Quality-control summary for replicate sample pair analyses of organic constituents in groundwater samples collected 

for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California, October to 

December 2010.

[Constituents for which all replicate pair samples were non-detections are not listed. Abbreviations: SD, percent standard deviation; >, greater than; <, less than; 

RL, reporting level]

Constituent Number of non-detections / 

number of replicate pair samples

Number of SDs > 1⁄2 RL / number of replicate pair 

samples with concentration < 5 times the RL 

Volatile organic compounds (VOCs) 

Chloroform (Trichloromethane) 4/5 0/1

Pesticides and pesticide degradates

Simazine 5/6 0/1

Table A4B. Quality-control summary for replicate sample pair analyses of inorganic constituents in groundwater samples collected for the 

Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California, October to December 2010.

[Constituents for which all replicate pair samples were non-detections are not listed. Abbreviations: SD, percent standard deviation; RSD, percent relative 

standard deviation; RL, reporting level; >, greater than; <, less than; ≤, less than or equal to; nv, no value in category]

Constituent

Number of nondetections or ≤-coded 

replicate pairs / 

number of replicate 

pair samples 

Number of SDs > 1⁄2 RL 

/ number of replicate 

pair samples with 

concentrations 

< 5 times the RL

Number of RSDs 

> 10 percent / number of 

replicate pair samples 

with concentrations 

> 5 times the RL

Trace Elements

Aluminum 2/5 0/3 nv

Antimony 2/5 0/2 0/1

Arsenic 0/5 0/3 0/2

Barium 0/5 nv 0/5

Boron 2/5 0/1 0/2

Chromium 1/5 0/4 nv

Cobalt 2/5 0/3 nv

Copper 1/5 0/4 nv

Iron 1/5 0/3 0/1

Lead 0/5 0/5 nv

Lithium 3/5 0/1 0/1

Manganese 1/5 0/3 0/1

Molybdenum 1/5 nv 0/4

Nickel 0/5 0/2 0/3

Selenium 2/5 0/1 0/2

Strontium 0/5 nv 0/5

Tungsten 4/5 0/1 nv

Uranium 0/5 0/3 0/2

Vanadium 1/5 nv 0/4

Zinc 0/5 0/2 0/3

Nutrients 

Ammonia (as nitrogen) 4/5 0/1 nv

Nitrate plus nitrite (as nitrogen) 1 2/5 0/3 nv

Total nitrogen (ammonia + nitrite + nitrate + organic nitrogen) 0/4 0/1 nv

Phosphate, orthophosphate (as phosphorus) 0/5 0/2 0/3
Appendix 77

Table A4C. Quality-control summary for replicate sample pair 

analyses of radioactive constituents in groundwater samples 

collected for the Klamath Mountains (KLAM) Groundwater 

Ambient Monitoring and Assessment (GAMA) study unit, 

California, October to December 2010.

[For activities of radioactive constituents, a replicate pair sample analysis is 

defined as acceptable if the p-value for the normalized absolute difference 

is less than the significance level, α = 0.05. Abbreviations: <, less than; 

>, greater than; —, not detected]

Constituent

Number of 

replicate pair 

samples with 

p < 0.05 /number 

of replicate pair 

samples 

Activities for replicate 

pair samples with 

p > 0.05 

(groundwater sample, 

replicate sample)

Gross alpha radioactivity, 

72-hour count

4/5 (—, 1.43)

Table A4D. Quality-control summary for replicate sample pair 

analyses of microbial indicators in groundwater samples collected 

for the Klamath Mountains (KLAM) Groundwater Ambient 

Monitoring and Assessment (GAMA) study unit, California, 

October to December 2010.

[Abbreviations: —, not detected; M, presence verified but not quantified]

Constituent

Number 

of nondetections 

/ number of 

replicate pair 

samples 

Results for 

replicate pair 

samples

(groundwater 

sample, replicate 

sample)

Total coliform (including 

fecal coliform and Escherichia 

coli [E. coli])

1/4 (—, M) (M, —) 

(M, —)

Constituent

Number of nondetections or ≤-coded 

replicate pairs / 

number of replicate 

pair samples 

Number of SDs > 1⁄2 RL 

/ number of replicate 

pair samples with 

concentrations 

< 5 times the RL

Number of RSDs 

> 10 percent / number of 

replicate pair samples 

with concentrations 

> 5 times the RL

Major and minor ions, silica, and total dissolved solids (TDS) 

Calcium 0/5 nv 0/5

Chloride 0/5 nv 0/5

Fluoride 1/5 0/2 0/2

Magnesium 0/5 nv 0/5

Potassium 0/5 nv 0/5

Sodium 0/5 nv 0/5

Sulfate 0/5 0/1 0/4

Silica (as SiO2

) 0/5 nv 0/5

TDS 0/5 nv 0/5

Arsenic and iron species

Arsenic (total) 0/4 nv 0/1

Iron (total) 2/5 nv 0/3

Iron-II 2/5 nv 0/3

1

 Nitrite plus nitrate (as nitrogen) is referred to as nitrate in the text for clarity.

Table A4B. Quality-control summary for replicate sample pair analyses of inorganic constituents in groundwater samples collected 

for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California, October to 

December 2010.—Continued

[Constituents for which all replicate pair samples were non-detections are not listed. Abbreviations: SD, percent standard deviation; RSD, percent relative 

standard deviation; RL, reporting level; >, greater than; <, less than; ≤, less than or equal to; nv, no value in category]
78 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Constituent 

(synonym or abbreviation)

Number of matrix-spike 

samples collected

Minimum recovery 

(percent)

Maximum recovery 

(percent)

Median recovery 

(percent)

Acetone 5 96 141 113

Acrylonitrile 5 94 124 102

tert-Amyl methyl ether (TAME) 5 80 90 83

Benzene 5 94 106 98

Bromobenzene 5 91 98 96

Bromochloromethane 5 96 106 101

Bromodichloromethane 1 5 83 96 90

Bromoform (Tribromomethane) 5 71 96 93

Bromomethane (Methyl bromide) 5 98 105 100

n-Butylbenzene 5 65 95 81

sec-Butylbenzene 5 86 102 92

tert-Butylbenzene 5 88 106 96

Carbon disulfide 1 5 69 104 72

Carbon tetrachloride (Tetrachloromethane) 5 77 97 89

Chlorobenzene 5 88 101 98

Chloroethane 5 96 112 100

Chloroform (Trichloromethane) 1 5 100 110 101

Chloromethane 5 97 121 103

3-Chloropropene 5 92 97 95

2-Chlorotoluene 5 84 99 92

4-Chlorotoluene 5 82 100 95

Dibromochloromethane 1 5 81 92 89

1,2-Dibromo-3-chloropropane (DBCP) 5 80 93 87

1,2-Dibromoethane (EDB) 5 94 108 98

Dibromomethane 5 93 104 97

1,2-Dichlorobenzene 5 86 101 97

1,3-Dichlorobenzene 5 83 100 93

1,4-Dichlorobenzene 5 85 102 95

trans-1,4-Dichloro-2-butene 5 48 104 91

Dichlorodifluoromethane (CFC-12) 5 74 99 81

1,1-Dichloroethane (1,1-DCA) 5 98 106 98

1,2-Dichloroethane (1,2-DCA) 5 96 114 100

1,1-Dichloroethene (1,1-DCE) 5 87 96 94

cis-1,2-Dichloroethene (cis-1,2-DCE) 5 93 102 95

trans-1,2-Dichloroethene (trans-1,2-DCE) 5 89 99 96

1,2-Dichloropropane 5 88 103 96

1,3-Dichloropropane 5 92 108 98

2,2-Dichloropropane 5 74 80 75

1,1-Dichloropropene 5 82 94 87

cis-1,3-Dichloropropene 5 82 94 84

trans-1,3-Dichloropropene 5 71 97 82

Diethyl ether 5 96 106 102

Diisopropyl ether (DIPE) 5 84 93 90

Table A5A. Quality-control summary for matrix-spike sample recoveries of volatile organic compounds (VOCs) in groundwater 

samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California, 

October to December 2010.

[Acceptable recovery range is between 70 and 130 percent]
Appendix 79

Table A5A. Quality-control summary for matrix-spike sample recoveries of volatile organic compounds (VOCs) in groundwater 

samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California, 

October to December 2010.—Continued

[Acceptable recovery range is between 70 and 130 percent]

Constituent 

(synonym or abbreviation)

Number of matrix-spike 

samples collected

Minimum recovery 

(percent)

Maximum recovery 

(percent)

Median recovery 

(percent)

Ethylbenzene 5 86 98 92

Ethyl tert-butyl ether (ETBE) 5 82 93 91

Ethyl methacrylate 5 85 94 87

o-Ethyl toluene 5 90 101 95

Hexachlorobutadiene 5 58 88 79

Hexachloroethane 5 73 95 87

2-Hexanone (n-Butyl methyl ketone) 5 88 101 95

Iodomethane (Methyl iodide) 5 100 131 107

Isopropylbenzene 5 85 99 94

4-Isopropyl-1-methyl benzene 5 78 101 87

Methyl acrylate 5 92 103 97

Methyl acrylonitrile 5 92 110 103

Methyl tert-butyl ether (MTBE) 1 5 91 98 96

Methyl iso-butyl ketone (MIBK) 5 87 99 94

Methylene chloride (Dichloromethane) 5 100 111 101

Methyl ethyl ketone (2-butanone, MEK) 1 5 91 122 100

Methyl methacrylate 5 85 94 88

Naphthalene 5 89 104 94

Perchloroethene (PCE, Tetrachloroethene) 1 5 92 111 100

n-Propylbenzene 5 79 99 84

Styrene 1 5 93 98 96

1,1,1,2-Tetrachloroethane 5 85 97 94

1,1,2,2-Tetrachloroethane 5 92 104 96

Tetrahydrofuran 5 95 114 102

1,2,3,4-Tetramethylbenzene 5 88 98 94

1,2,3,5-Tetramethylbenzene 5 87 99 96

Toluene 1 5 95 107 105

1,2,3-Trichlorobenzene 5 83 103 95

1,2,4-Trichlorobenzene 5 72 94 86

1,1,1-Trichloroethane (1,1,1-TCA) 5 93 103 99

1,1,2-Trichloroethane (1,1,2-TCA) 5 87 106 100

Trichloroethene (TCE) 1 5 85 98 96

Trichlorofluoromethane (CFC-11) 5 100 117 105

1,2,3-Trichloropropane (1,2,3-TCP) 5 93 107 100

Trichlorotrifluoroethane (CFC-113) 5 85 101 95

1,2,3-Trimethylbenzene 5 93 102 100

1,2,4-Trimethylbenzene 5 81 133 100

1,3,5-Trimethylbenzene 5 85 98 93

Vinyl bromide (Bromoethene) 5 96 101 100

Vinyl chloride (Chloroethene) 5 96 124 101

m- plus p-Xylene 5 91 100 94

o-Xylene 5 90 98 94

1

 Constituent detected in groundwater sample(s).
80 Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program

Table A5B. Quality-control summary for matrix-spike sample recoveries of pesticides and pesticide degradates in groundwater 

samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California, 

October to December 2010.

[Acceptable recovery range is between 70 and 130 percent]

Constituent 

(synonym or abbreviation)

Number of matrixspike samples 

collected

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Acetochlor 5 82 100 95

Alachlor 5 87 101 95

Atrazine 1 5 77 103 94

Azinphos-methyl 5 82 115 97

Azinphos-methyl oxon 5 48 103 82

Benfluralin 5 63 72 68

Carbaryl 5 75 102 98

2-Chloro-2,6-diethylacetanilide 5 88 105 103

4-Chloro-2-methylphenol 5 58 85 75

Chlorpyrifos 5 75 93 82

Chlorpyrifos oxon 5 28 53 50

Cyfluthrin 5 56 80 64

Cypermethrin 5 54 77 66

DCPA (Dacthal) 5 98 106 104

Deethylatrazine (2-Chloro-4-isopropylamino-6-amino-s-triazine) 1 5 69 101 78

Desulfinylfipronil 5 81 103 97

Desulfinylfipronil amide 5 81 89 87

Diazinon 5 87 97 95

3,4-Dichloroaniline 5 77 89 85

Dichlorvos 5 15 45 33

Dicrotophos 5 31 46 36

Dieldrin 5 87 98 92

2,6-Diethylaniline 5 95 100 97

Dimethoate 5 51 72 58

Ethion 5 62 72 69

Ethion monoxon 5 78 100 84

2-Ethyl-6-methylaniline 5 86 95 95

Fenamiphos 5 84 97 90

Fenamiphos sulfone 5 90 115 103

Fenamiphos sulfoxide 5 17 53 39

Fipronil 5 79 104 92

Fipronil sulfide 5 70 95 82

Fipronil sulfone 5 73 84 77

Fonofos 5 87 92 89

Hexazinone 1 5 58 74 65

Iprodione 5 54 91 66

Isofenphos 5 74 95 89

Malaoxon 5 70 91 84

Malathion 5 68 95 89

Metalaxyl 5 87 107 103
Appendix 81

Constituent 

(synonym or abbreviation)

Number of matrixspike samples 

collected

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Methidathion 5 82 92 86

Metolachlor 5 78 102 92

Metribuzin 5 69 93 84

Myclobutanil 5 75 85 76

1-Naphthol 5 33 73 51

Paraoxon-methyl 5 49 84 68

Parathion-methyl 5 73 90 83

Pendimethalin 5 68 91 80

cis-Permethrin 5 55 73 62

Phorate 5 70 87 80

Phorate oxon 5 83 102 96

Phosmet 5 15 51 42

Phosmet oxon 5 13 64 45

Prometon 5 72 97 92

Prometryn 5 77 101 94

Pronamide 5 78 100 97

Simazine 1 5 82 98 95

Tebuthiuron 5 106 139 116

Terbufos 5 77 87 81

Terbufos oxon sulfone 5 58 86 71

Terbuthylazine 5 88 106 101

Tribufos 5 43 57 55

Trifluralin 5 68 78 75

1

 Constituent detected in groundwater sample(s).

Table A5B. Quality-control summary for matrix-spike sample recoveries of pesticides and pesticide degradates in groundwater 

samples collected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California, 

October to December 2010.—Continued

[Acceptable recovery range is between 70 and 130 percent]
Table A6. Quality-control summary for surrogate compound recoveries of volatile organic compounds (VOCs) and pesticides and pesticide degradatcollected for the Klamath Mountains (KLAM) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California, October to December [Abbreviations: NWQL, U.S. Geological Survey National Water Quality Laboratory; VOC, volatile organic compound; <, less than; >, greater than] Surrogate compound NWQL analytical schedule Constituent class analyzed Number of blank samples analyzed Median recovery in field blank samples (percent) Number of surrogate recoveries < 70 percent in field blank samples Number of surrogate recoveries > 130 percent in field blank samples Number of groundwater samples analyzed Median recovery in groundwater samples (percent) N

s

re

< 70 

gro

s

1-Bromo-4-fluorobenzene 2020 VOC 4 90 0 0 39 92 1,2-Dichloroethane-d4 2020 VOC 4 119 0 0 39 120 Toluene-d8 2020 VOC 4 95 0 0 39 96 Diazinon-d10 2003 Pesticide 5 77 1 0 39 77 α-HCH-d6 2003 Pesticide 5 90 0 0 39 96 
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Mathany and Belitz—Groundwater-Quality Data in the Klamath Mountains Study Unit, 2010: Results from the California GAMA Program—Data Series 803