U.S. Department of the Interior

U.S. Geological Survey

Tulakeelake

Chico

Alturas

Yreka

Mount

Shasta

Redding

Burney

Susanville

LAVA BEDS

NATIONAL

MONUMENT

LASSEN VOLCANIC

NATIONAL PARK

 

Prepared in cooperation with the California State Water Resources Control Board 

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

Groundwater-Quality Data in the Cascade Range and 

Modoc Plateau Study Unit, 2010: Results from the California 

GAMA Program

U.S. Department of the Interior

U.S. Geological Survey

Data Series 688
Top cover photo: Well in Lassen County, California. Photograph taken by 

Stephen Schmitt, U.S. Geological Survey.

Bottom cover photo: View looking west toward Mount Shasta. Photograph 

taken by George Bennett, U.S. Geological Survey. 
Groundwater-Quality Data in the Cascade Range and 

Modoc Plateau Study Unit, 2010: Results from the 

California GAMA Program

By Jennifer L. Shelton, Miranda S. Fram, 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 688

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director 

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

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

reproduce any copyrighted materials contained within this report.

Suggested citation:

Shelton, J.L., Fram, M.S., and Belitz, Kenneth, 2013, Groundwater-quality data in the Cascade Range and Modoc 

Plateau study unit, 2010—Results from the California GAMA Program: U.S. Geological Survey Data Series 688, 124 p.
iii

Contents

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

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

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

Hydrogeologic Setting ..................................................................................................................................5

Sacramento Valley Eastside Study Area (ES)..................................................................................9

Honey Lake Valley Study Area (HL) ...................................................................................................9

Shasta Valley and Mount Shasta Volcanic Area Study Area (SH).............................................17

Cascade Range and Modoc Plateau Low Use Basins Study Area (LU)....................................17

Quaternary Volcanic Areas (QV) and Tertiary Volcanic Areas (TV) Study Areas ....................19

Methods ........................................................................................................................................................19

Study Design........................................................................................................................................19

Sample Collection and Analysis.......................................................................................................20

Data Reporting.....................................................................................................................................21

Quality Assurance ..............................................................................................................................21

Water-Quality Results ................................................................................................................................21

Quality-Control Results ......................................................................................................................21

Comparison Benchmarks ..................................................................................................................21

Groundwater-Quality Data ................................................................................................................22

Water-Quality Indicators .........................................................................................................23

Organic and Special-Interest Constituents...........................................................................23

Volatile Organic Compounds (VOCs) .............................................................................23

Pesticides...........................................................................................................................24

Perchlorate ........................................................................................................................24

Inorganic Constituents..............................................................................................................24

Nutrients.............................................................................................................................24

Trace Elements..................................................................................................................24

Uranium and Radioactive Constituents.........................................................................24

Inorganic Constituents with SMCL Benchmarks ........................................................25

Geochemical and Age-Dating Tracers...................................................................................25

Microbial Indicators..................................................................................................................26

Future Work ..................................................................................................................................................26

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

Acknowledgments.......................................................................................................................................27

References Cited..........................................................................................................................................27

Appendix .....................................................................................................................................................100
iv

Figures

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

Cascade Range and Modoc Plateau (CAMP) study unit, California GAMA 

Priority Basin Project........................................................................ 4

Figure 2. Map showing simplified geology of northeastern California, and the 

boundaries of hydrogeologic provinces, geomorphic provinces, and counties ... 6

Figure 3. Map showing boundaries of the six study areas in the Cascade Range and

Modoc Plateau (CAMP) study unit, California GAMA Priority Basin Project,

boundaries of study area buffers, and locations of wells in the California

Department of Public Health database and wells sampled for this study ............ 10

Figure 4. Maps showing the northwestern, north-central, northeastern, west-central,

southwestern, and southeastern parts of the Cascade Range and Modoc 

Plateau (CAMP) study unit, California GAMA Priority Basin Project, boundaries 

of study areas and study area buffers, and locations of selected hydrologic 

and geologic features, wells sampled for this study, and other wells in the 

California Department of Public Health (CDPH) database.............................. 11

Tables

Table 1. Study area names, study area and grid cell sizes, and numbers of CDPH wells

and USGS-grid wells in each study area, Cascade Range and Modoc Plateau

(CAMP) study unit, July through October 2010, California GAMA Priority Basin

Project ....................................................................................... 38

Table 2. Identification, sampling, and construction information for wells sampled for 

the Cascade Range and Modoc Plateau (CAMP) study unit, July through 

October 2010, California GAMA Priority Basin Project ................................. 38

Table 3. Classes of chemical constituents and field water-quality indicators collected 

for the Cascade Range and Modoc Plateau (CAMP) study unit, July through 

October 2010, California GAMA Priority Basin Project ................................. 41

Table 4A. Volatile organic compounds (VOCs), primary uses or sources, comparative

benchmarks, and reporting information for the U.S. Geological Survey (USGS)

National Water Quality Laboratory Schedule 2020. .................................... 42

Table 4B. Pesticides and pesticide degradates, primary uses or sources, comparative

benchmarks, and reporting information for the U.S. Geological Survey (USGS)

National Water Quality Laboratory Schedule 2003 .................................... 46

Table 4C. Perchlorate, primary uses or sources, comparative benchmarks, and reporting

information for Weck Laboratories, Inc., analyses .................................... 48

Table 4D. Nutrients, comparative benchmarks, and reporting information for the U.S.

Geological Survey (USGS) National Water Quality Laboratory Schedule 2755 ...... 48

Table 4E. Trace elements, comparative benchmarks, and reporting information for the U.S.

Geological Survey (USGS) National Water Quality Laboratory Schedule 1948 ...... 49

Table 4F. 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 Schedule 1948 .................. 50

Table 4G. Radioactive constituents, comparative benchmarks, and reporting information 

for laboratory analyses ..................................................................... 51

Table 4H. Arsenic and iron species, comparative benchmarks, and reporting information

for the U.S. Geological Survey (USGS) Trace Metal Laboratory, Boulder, Colorado,

analyses .................................................................................... 51
v

Tables—Continued

Table 4I. Dissolved gases and isotope tracers, comparison benchmarks and reporting

information for laboratory analyses ...................................................... 52

Table 4J. Microbial indicators, comparative benchmarks, and reporting information for 

the IDEXX Colilert® field test kit analyses................................................ 52

Table 5. Field water-quality indicators in samples collected for the Cascade Range and

Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA

Priority Basin Project........................................................................ 53

Table 6. Volatile organic compounds (VOCs) detected in samples collected for 

the Cascade Range and Modoc Plateau (CAMP) study unit, July through 

October 2010, California GAMA Priority Basin Project ................................. 58

Table 7. Pesticides and pesticide degradates detected in samples collected for 

the Cascade Range and Modoc Plateau (CAMP) study unit, July through 

October 2010, California GAMA Priority Basin Project ................................. 65

Table 8. Results for analyses of perchlorate in samples collected for the Cascade Range

and Modoc Plateau (CAMP) study unit, July through October 2010, California

GAMA Priority Basin Project............................................................... 68

Table 9. Nutrients detected in samples collected for the Cascade Range and Modoc

Plateau (CAMP) study unit, July through October 2010, California GAMA Priority

Basin Project................................................................................. 70

Table 10. Trace elements detected in samples collected for the Cascade Range and 

Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA 

Priority Basin Project ..................................................................... 73

Table 11. Major and minor ions, silica, and total dissolved solids (TDS) detected in 

samples collected for the Cascade Range and Modoc Plateau (CAMP) study 

unit, July through October 2010, California GAMA Priority Basin Project ............ 82

Table 12. Uranium isotopes detected in samples collected for the Cascade Range 

and Modoc Plateau (CAMP) study unit, July through October 2010, California 

GAMA Priority Basin Project............................................................... 86

Table 13. Radon-222 detected in samples collected for the Cascade Range and Modoc

Plateau (CAMP) study unit, July through October 2010, California GAMA Priority

Basin Project................................................................................. 87

Table 14. Gross alpha and gross beta particle activities detected in samples collected 

for the Cascade Range and Modoc Plateau (CAMP) study unit, July through 

October 2010, California GAMA Priority Basin Project ................................. 89

Table 15. Results for analyses of species of inorganic arsenic and iron in samples

collected for the Cascade Range and Modoc Plateau (CAMP) Groundwater

Ambient Monitoring and Assessment (GAMA) study unit, July through 

October 2010, California GAMA Priority Basin Project ................................. 92

Table 16. Results for analyses of stable isotope ratios, tritium activity, and carbon-14

abundance detected in samples collected for the Cascade Range and Modoc

Plateau (CAMP) Groundwater Ambient Monitoring and Assessment (GAMA)

study unit, July through October 2010, California GAMA Priority Basin Project ... 95

Table 17. Microbial indicator constituents detected in samples collected for the Cascade

Range and Modoc Plateau (CAMP) study unit, July through October 2010,

California GAMA Priority Basin Project................................................... 98
vi

Conversion Factors, Datums, and Abbreviations

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 2.590 square kilometer (km2) 

Flow rate

cubic foot per second (ft3

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

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

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

Mass

pound, avoirdupois (lb) 0.4536 kilogram (kg)

Radioactivity

picocurie per liter (pCi/L) 0.037 becquerel per liter (Bq/L)

Transmissivity*

foot squared per day (ft2

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

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

meter (m) 3.2808399 foot (ft)

kilometer (km) 0.6214 mile (mi)

Area

square kilometer (km2) 0.3861 square mile (mi2)

Volume

liter (L) 1.0567 quart (qt)

Mass

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).

Turbidity is given in nephelometric turbidity units (NTU).

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

or micrograms per liter (μg/L). 
vii

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 are given in picocuries per liter (pCi/L). 

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

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

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

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).

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) and feet below mean sea level (ft below msl).

Selected Terms and Symbols

α confidence level

cm3

 STP/gH2O cubic centimeters of gas at standard temperature and pressure (0 degrees Celsius and 

1 atmosphere of pressure) per gram of water

δi

E 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

M detected presence of microbial indicator (total coliform or Escherichia coli [E. coli])

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

-- not detected

p significant level

pH measure of the acidity of water

pK1,2 acid dissociation constants of carbonic acid

pKw acid dissociation constant of water

U absence detected or presence not detected of microbial indicator (total coliform or 

E. coli)

z test statistic

± plus or minus

* value is greater than benchmark level or outside benchmark range

** value is greater than upper benchmark level

Conversion Factors, Datums, and Abbreviations—Continued
viii

Abbreviations and Acronyms

AL-US action level (USEPA)

APE Alternate Place Entry Form program designed for USGS sampling

CAMP Cascade Range and Modoc Plateau study unit

CAS Chemical Abstract Service (American Chemical Society)

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

CSU combined standard uncertainty

DWP Domestic Well Project

E estimated or having a higher degree of uncertainty

R radioactive constituent not detected

ES Sacramento Valley Eastside study area

GAMA Groundwater Ambient Monitoring and Assessment Program

GIS geographic information system

GPS Global Positioning System

HAL-US lifetime health advisory level (USEPA)

HL Honey Lake Valley study area

HPLC high-performance liquid chromatography

IBSP Inorganic Blind Sample Project (USGS BQS)

LRL laboratory reporting level

LSD land surface datum

LT-MDL long-term method detection level

LU Cascade Range and Modoc Plateau Low Use Basins study area

MCL-US maximum contaminant level (USEPA)

MCL-CA maximum contaminant level (CDPH)

MDL method detection limit

MRL minimum reporting level

MU method uncertainty

na not available

nc not collected

NL-CA notification level (CDPH)

nv no measured value or no value in category

np no preference

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

QV Quaternary Volcanic Areas study area

RL reporting level

RPD relative percent difference

RSD relative standard deviation

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

SD standard deviation

SH Shasta Valley and Mount Shasta Volcanic Area study area

Conversion Factors, Datums, and Abbreviations—Continued
ix

SMCL-CA secondary maximum contaminant level (CDPH)

SMCL-US secondary maximum contaminant level (USEPA)

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

ssLC sample-specific critical level

TT-US treatment technique action level established by the USEPA

TV Tertiary Volcanic Areas study area

U.S. United States

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

NAWQA National Water-Quality Assessment Program (USGS)

NELAP National Environmental Laboratory Accreditation Program

NWQL National Water Quality Laboratory (USGS)

SWRCB California State Water Resources Control Board

TML Trace Metal Laboratory (USGS)

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

Selected Chemical Names

CaCO3 calcium carbonate

CO3

–2 carbonate

CFC chlorofluorocarbon

DO dissolved oxygen

H2

O water

HCl hydrochloric acid

HCO3

– bicarbonate

MTBE methyl tert-butyl ether

PCE perchloroethene (tetrachloroethene)

SiO2 silicon dioxide

TCE trichloroethene

TDS total dissolved solids

THM trihalomethane

VOC volatile organic compound

Conversion Factors, Datums, and Abbreviations—Continued

Abbreviations and Acronyms—Continued
x

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Groundwater-Quality Data in the Cascade Range and 

Modoc Plateau Study Unit, 2010: Results from the 

California GAMA Program

By Jennifer L. Shelton, Miranda S. Fram, and Kenneth Belitz

Abstract 

Groundwater quality in the 39,000-square-kilometer 

Cascade Range and Modoc Plateau (CAMP) study unit was 

investigated by the U.S. Geological Survey (USGS) from July 

through October 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 CAMP study unit is the thirty-second study unit 

to be sampled as part of the GAMA PBP.

The GAMA CAMP study was designed to provide a 

spatially unbiased assessment of untreated-groundwater 

quality in the primary aquifer system and to facilitate 

statistically consistent comparisons of untreated-groundwater 

quality throughout California. The primary aquifer system is 

defined as that part of the aquifer corresponding to the open or 

screened intervals of wells listed in the California Department 

of Public Health (CDPH) database for the CAMP study unit. 

The quality of groundwater in shallow or deep water-bearing 

zones may differ from the quality of groundwater in the 

primary aquifer system; shallow groundwater may be more 

vulnerable to surficial contamination.

In the CAMP study unit, groundwater samples were 

collected from 90 wells and springs in 6 study areas 

(Sacramento Valley Eastside, Honey Lake Valley, Cascade 

Range and Modoc Plateau Low Use Basins, Shasta Valley and 

Mount Shasta Volcanic Area, Quaternary Volcanic Areas, and 

Tertiary Volcanic Areas) in Butte, Lassen, Modoc, Plumas, 

Shasta, Siskiyou, and Tehama Counties. Wells and springs 

were selected by using a spatially distributed, randomized 

grid-based method to provide statistical representation of the 

study unit (grid wells).

Groundwater samples were analyzed for field waterquality indicators, organic constituents, perchlorate, inorganic 

constituents, radioactive constituents, and microbial indicators. 

Naturally occurring isotopes and dissolved noble gases also 

were measured to provide a dataset that will be used to help 

interpret the sources and ages of the sampled groundwater in 

subsequent reports. In total, 221 constituents were investigated 

for this study. 

Three types of quality-control samples (blanks, 

replicates, and matrix spikes) were collected at approximately 

10 percent of the wells in the CAMP study unit, and the results 

for these samples were used to evaluate the quality of the 

data for the groundwater samples. Blanks rarely contained 

detectable concentrations of any constituent, suggesting that 

contamination from sample collection procedures was not 

a significant source of bias in the data for the groundwater 

samples. Replicate samples generally were within the limits of 

acceptable analytical reproducibility. Matrix-spike recoveries 

were within the acceptable range (70 to 130 percent) for 

approximately 90 percent of the compounds.

This study did not attempt to evaluate the quality of water 

delivered to consumers; after withdrawal from the ground, 

untreated groundwater typically is treated, disinfected, and 

(or) blended with other waters to maintain water quality. 

Regulatory benchmarks apply to water that is served 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-regulatory benchmarks 

established for aesthetic concerns by 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.
2 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

All organic constituents and most inorganic constituents 

that were detected in groundwater samples from the 90 grid 

wells in the CAMP study unit were detected at concentrations 

less than drinking-water benchmarks. 

Of the 148 organic constituents analyzed, 27 were 

detected in groundwater samples; concentrations of 

all detected constituents were less than regulatory and 

nonregulatory health-based benchmarks, and all were less than 

1/10 of benchmark levels. One or more organic constituents 

were detected in 52 percent of the grid wells in the CAMP 

study unit: VOCs were detected in 30 percent, and pesticides 

and pesticide degradates were detected in 31 percent. 

Trace elements, major ions, nutrients, and radioactive 

constituents were sampled for at 90 grid wells in the CAMP 

study unit, and most detected concentrations were less than 

health-based benchmarks. Exceptions include three detections 

of arsenic greater than the USEPA maximum contaminant 

level (MCL-US) of 10 micrograms per liter (μg/L), two 

detections of boron greater than the CDPH notification level 

(NL-CA) of 1,000 μg/L, two detections of molybdenum 

greater than the USEPA lifetime health advisory level 

(HAL-US) of 40 μg/L, two detections of vanadium greater 

than the CDPH notification level (NL-CA) of 50 μg/L, one 

detection of nitrate, as nitrogen, greater than the MCL-US 

of 10 milligrams per liter (mg/L), two detections of uranium 

greater than the MCL-US of 30 μg/L and the MCL-CA of 

20 picocuries per liter (pCi/L), one detection of radon-222 

greater than the proposed MCL-US of 4,000 pCi/L, and two 

detections of gross alpha particle activity greater than the 

MCL-US of 15 pCi/L. 

Results for inorganic constituents with non-regulatory 

benchmarks set for aesthetic concerns showed that iron 

concentrations greater than the CDPH secondary maximum 

contaminant level (SMCL-CA) of 300 μg/L were detected 

in four grid wells. Manganese concentrations greater than 

the SMCL-CA of 50 μg/L were detected in nine grid wells. 

Chloride and TDS were detected at concentrations greater 

than the upper SMCL-CA benchmarks of 500 mg/L and 

1,000 mg/L, respectively, in one grid well. 

Microbial indicators (total coliform and Escherichia 

coli [E. coli]) were detected in 11 percent of the 83 grid wells 

sampled for these analyses in the CAMP study unit. The 

presence of total coliform was detected in nine grid wells, 

and the presence of E. coli was detected in one of these same 

grid wells. 

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 

(website at http://www.waterboards.ca.gov/water_issues/

programs/gama/). 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 

(website at http://ca.water.usgs.gov/gama/); (2) the GAMA 

Domestic Well Project conducted by the SWRCB; (3) the 

GAMA Special Studies Project conducted by LLNL; and 

(4) the GeoTracker GAMA online database conducted by the 

SWRCB. The GAMA PBP primarily focuses on the deep part 

of the groundwater resource, which is typically used for public 

drinking-water supply. The GAMA Domestic Well Project 

generally focuses on the shallow 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. 

All published and quality-assurance/quality-control 

(QA/QC) approved analytical data collected for the GAMA 

Program are stored in the web-based GeoTracker GAMA 

Database (website at https://geotracker.waterboards.ca.gov/

gama/). The GeoTracker GAMA Database also stores 

groundwater-quality data and related reports collected by other 

State agencies, such as the California Department of Public 

Health (CDPH), California Department of Water Resources 

(CDWR), California Department of Pesticide Regulation 

(CDPR), and data collected by the SWRCB and Regional 

Boards from environmental monitoring wells at contaminated 

and (or) remediated sites.

The GAMA Program was initiated by the SWRCB 

in 2000 and later expanded by the Groundwater Quality 

Monitoring Act of 2001 (State of California, 2001a, 2001b). 

The GAMA PBP assesses groundwater quality in groundwater 

basins and areas outside of basins that account for most of 

the groundwater resources used for public drinking-water 

supply in the State. For the GAMA PBP, the USGS, in 

collaboration with the SWRCB, developed the 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, 

CDPH, CDWR, CDPR, local water agencies, and well owners 

(Kulongoski and Belitz, 2004). Participation in the project is 

entirely voluntary.

The GAMA PBP is unique in California because it 

includes many chemical analyses that are not otherwise 

available in statewide water-quality monitoring datasets. 
Introduction 3

Groundwater samples collected for the project are typically 

analyzed for approximately 200 to 300 chemical constituents 

by using analytical methods with lower detection limits than 

required by the CDPH for regulatory monitoring of drinkingwater 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 that required by 

CDPH and for a suite of chemical and isotopic tracers for 

exploring hydrologic and geochemical processes. A broader 

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.

The ranges of hydrologic, geologic, and climatic 

conditions in California were considered in this assessment 

of groundwater quality. Belitz and others (2003) partitioned 

the State into 10 hydrogeologic provinces, each with 

distinctive hydrologic, geologic, and climatic characteristics: 

Cascade Range 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 groundwater basins designated by the 

CDWR (California Department of Water Resources, 2003). 

Groundwater basins generally consist of relatively permeable, 

unconsolidated deposits of alluvial or volcanic origin. 

Eighty percent of California’s approximately 16,000 active 

and standby drinking-water wells listed in the statewide 

database maintained by the CDPH (hereinafter referred to as 

CDPH wells) are located in groundwater basins within the 

10 hydrogeologic provinces.

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 registered pesticide applications 

(Belitz and others, 2003). Of the 472 basins designated by 

the CDWR, 116 priority basins were selected and grouped 

into 35 GAMA study units, representing approximately 

95 percent of the CDPH wells in groundwater basins. In 

addition, some areas outside of the defined groundwater basins 

were included in the nearest respective study unit to achieve 

representation of the 20 percent of the CDPH wells not located 

in the groundwater basins. The Cascade Range and Modoc 

Plateau study unit (hereinafter referred to as the CAMP study 

unit) corresponds to the Cascade Range and Modoc Plateau 

hydrologic province, and includes groundwater basins and 

areas outside of basins.

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 (Kulongoski and 

Belitz, 2004). The assessments are intended to characterize 

the quality of groundwater in the primary aquifer systems 

of the study units, not the treated drinking water delivered 

to consumers by water purveyors. The primary aquifer 

system is defined as that part of the aquifer corresponding to 

the open or screened intervals of wells listed in the CDPH 

databases for the study units. The CDPH database lists wells 

used for municipal and community drinking-water supplies, 

and includes wells from systems classified as non-transient 

(such as those in cities, towns, and mobile-home parks) 

and transient (such as those in schools, campgrounds, and 

restaurants). Collectively, the CDPH refers to these wells as 

“public-supply” wells. Groundwater quality in shallow or 

deep parts of the aquifer systems may differ from that in the 

primary aquifer system. In particular, shallow groundwater 

may be more vulnerable to surface contamination. As a result, 

samples from shallow wells (such as many private domestic 

wells and environmental monitoring wells) can have higher 

concentrations of constituents from anthropogenic sources 

(such as volatile organic compounds and nitrate) than samples 

from wells screened in the underlying primary aquifer system 

(Landon and others, 2010).

This USGS Data Series Report is the first in a series 

of reports presenting the water-quality data collected in the 

CAMP study unit and is similar to other USGS Data Series 

Reports written for the GAMA PBP study units sampled to 

date. Data Series Reports and additional reports addressing the 

status, understanding, and trends aspects of the water-quality 

assessments of each study unit are available from the U.S. 

Geological Survey (2011b), at http://ca.water.usgs.gov/gama/

includes/GAMA_publications.html.

Purpose and Scope

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

design, including the hydrogeologic setting of the CAMP 

study unit and the study methods; (2) the analytical results 

for groundwater samples collected in the CAMP study unit, 

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

were analyzed for field water-quality indicators, organic, 

special-interest, inorganic, and radioactive constituents, 

naturally occurring isotopes, and dissolved gases. The 

chemical data presented in this report were evaluated by 

comparison to State and Federal drinking-water regulatory 

and other non-regulatory standards that are applied to treated 

drinking water. Regulatory and non-regulatory benchmarks 

considered for this report 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.
4 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006. 

Albers Equal Area Conic Projection

North American Datum of 1983 (NAD 83)

Provinces from Belitz and others (2003)

OREGON

NEVADA

MEXICO

ARIZONA

0 200 MILES

0 200 KILOMETERS

40

42 124 122 120 118 116 114

38

36

34

PA C I F I C O C E A N

Bakersfield

Los Angeles

San Diego

Redding

SacramentoSacramento

San

Francisco

Valley

Klamath

Mountains

Cascade Range and

Modoc Plateau

(CAMP) study unit

Transverse Ranges and

selected Peninsular Ranges

Southern Coast

Ranges

Sierra

Nevada

Northern

Coast

Ranges

Desert

Central

Basin and Range

San Diego

Drainages

Figure 1. Hydrogeologic provinces of California and the location of the Cascade Range and Modoc Plateau 

(CAMP) study unit, California GAMA Priority Basin Project. 
Hydrogeologic Setting 5

Hydrogeologic Setting 

The CAMP study unit corresponds to the Cascade 

Range and Modoc Plateau hydrogeologic province in the 

northeastern corner of the State (fig. 1; Belitz and others, 

2003). The study unit covers an area of 39,000 square 

kilometers (km2) in Modoc, Lassen, Siskiyou, Shasta, Butte, 

Tehama, and Plumas Counties (fig. 2A). The province is 

defined on the basis of geologic and State boundaries; it is 

bounded to the west by the Mesozoic and Paleozoic rocks of 

the Klamath Mountains province, to the south by Mesozoic 

and Paleozoic rocks of the Sierra Nevada province, to the 

southwest by the Cenozoic sediment deposits of the Central 

Valley province, and to the north by the Oregon State line, and 

to the east by the Nevada State line. The Cascade Range and 

Modoc Plateau hydrogeologic province consists of Cenozoic 

volcanic rocks and sediment deposits. The hydrogeologic 

province includes three geomorphic provinces (fig. 2A): the 

western part is part of the Cascade Range, the central and 

eastern part is the Modoc Plateau, and two basins on the 

eastern edge are considered part of the Basin and Range 

(California Department of Conservation, California Geological 

Survey, 2002).

Hydrologic features of the CAMP study unit belong to 

three major watersheds: the Sacramento River watershed 

(CDWR basin numbers beginning with “5-”), the Klamath 

River watershed (CDWR basin numbers beginning with “1-”), 

and closed basins of the north Lahontan region (CDWR basin 

numbers beginning with “6-”) (fig. 2B) (California Department 

of Water Resources, 2003). The largest river in the study unit, 

the Pit River, flows across the study unit from Goose Lake in 

the northeast to Lake Shasta on the Sacramento River. The 

headwaters of the Sacramento River are on the southwestern 

slopes of Mount Shasta. Creeks in the southwestern part of the 

study unit flow into the main stem of the Sacramento River. 

Along the Oregon border, the Lost River drainage, including 

Clear Lake and Tule Lake, is connected to the Klamath River 

by a man-made canal. The Shasta River flows through Shasta 

Valley and enters the Klamath River below Iron Gate Dam. In 

the North Lahontan region along the Nevada border, the basins 

are closed basins; rivers drain into perennial or intermittent 

lakes in the basins.

Climate in the study area varies with elevation and 

longitude. Land-surface elevations in the study unit range 

from approximately 1,500 feet (ft) along the margin of the 

Sacramento Valley to 14,179 ft on Mount Shasta. Precipitation 

is greatest on the western side of the study unit, reaching up to 

80 inches per year (in/yr) on Mount Shasta and up to 120 in/yr 

in high elevations in Lassen Volcanic National Park (PRISM 

Group, Oregon State University, 2010). Elevation ranges from 

4,000 to 5,500 ft throughout most of the central and eastern 

parts of the study unit, and climate is classified as the Great 

Basin desert (defined as high, cold desert). The central and 

eastern parts of the study unit are in the rain shadow of the 

Cascade Range and therefore receive much less precipitation 

than the western parts of the study unit. Average annual 

precipitation is 10–20 in/yr in most of the area and 20–40 in/yr 

at higher elevations (Western Regional Climate Center, 2010). 

Much of the precipitation in the entire study unit falls as snow, 

particularly at elevations above 4,500 ft, and nearly all of the 

precipitation occurs in the winter (between November and 

May). Summers are hot and dry.

 Geologically, the CAMP study unit consists entirely of 

Cenozoic-age volcanic and sedimentary rocks and deposits. 

The western part of the study unit is part of the Cascade Range 

(fig. 2A), a volcanic arc extending from southern British 

Columbia to northern California. The Cascade Range has been 

an active volcanic arc for the last approximately 36 million 

years (Ma) as a result of subduction of the Juan de Fuca plate 

under the North American plate (Bally and Palmer, 1989). 

The oldest rocks in the study unit are mid-Tertiary (33 Ma to 

20 Ma) volcanic rocks of the Western Cascade Range, an old, 

deeply eroded ancestor of the modern High Cascade Range 

volcanoes, and these rocks are exposed north of Shasta Valley. 

The High Cascade Range in California consists of 

three volcanic areas: Mount Shasta, the Lassen area, and the 

Medicine Lake Volcano. The Mount Shasta magmatic system 

has been active for approximately 600,000 years, and the 

current mountain is a composite of four major cones erupted 

over the last 250,000 years (Wood and Kienle, 1990). The 

most recent eruption in the youngest cone was in 1786, and 

there are still active fumeroles and hot springs on the summit. 

The mountain is formed primarily of andesitic lava flows and 

pyroclastic deposits. Mount Shasta also has five glaciers on it.

 The Lassen volcanic area, much of which is in Lassen 

Volcanic National Park, has a complex eruptive history, with 

537 volcanic vents younger than 7 Ma (Guffanti and others, 

1990). On a regional scale, the area consists of hundreds of 

coalescing small volcanoes primarily formed of basalt and 

basaltic andesite lavas, and superimposed on the regional 

volcanism is a series of five volcanic centers (Clynne, 1990; 

Guffanti and others, 1990). Lassen is the most recent volcanic 

center and has been active for approximately 600,000 years. 

The youngest feature is a dacite dome field on the flank of the 

now-eroded main andesitic cone. One of these domes, Lassen 

Peak, last erupted during 1915–1921.

Medicine Lake Volcano is located behind the main 

line of Cascade Range volcanic arc volcanoes. It is a large 

shield volcano covering approximately 2,000 km2 and 

formed primarily of basalt and basaltic andesite lavas erupted 

during the late Pleistocene (<1 Ma) (Donnelly-Nolan, 

1988). The most recent eruptions were small rhyolite flows 

occurring approximately 900 years ago (Donnelly-Nolan and 

others, 1990).
6 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Figure 2. (A) Simplified geology of northeastern California, and the boundaries of hydrogeologic provinces, geomorphic provinces, 

and counties. (B) Map showing locations of California Department of Water Resources groundwater basins in the Cascade Range and 

Modoc Plateau (CAMP) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, and the locations of counties, major 

cities, topographic features, and hydrogeologic features.

sac12-0457_fig 02A

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006 

Albers Equal Area Conic Projection

North American Datum of 1983 (NAD 83)

Modified from Division of Mines and Geology,

CD-ROM 2000–007 (2000), GIS Data for the

Geologic Map of California

LASSEN CO

MODOC CO

SHASTA CO

SISKIYOU

PLUMAS CO

TEHAMA CO

GLENN CO BUTTE CO

SIERRA CO

TRINITY CO

YUBA CO

NEVADA CO

Modoc Plateau

Sierra Nevada

Province

Central Valley

Province

Cascade Range

Klamath Mountains

Province

North Coast Province

LASSEN CO

MODOC CO

SHASTA CO

SISKIYOU

PLUMAS CO

TEHAMA CO

GLENN CO BUTTE CO

SIERRA CO

TRINITY CO

YUBA CO

NEVADA CO

Modoc Plateau

Sierra Nevada

Province

Central Valley

Province

Cascade Range

Basin and Range

Basin and

Range

Klamath Mountains

Province

North Coast Province

122° 121° 120°

42°

41°

40°

(A)

Basin and Range

Basin and

Range

0 10 20 MILES

0 10 20 KILOMETERS

EXPLANATION

Geologic units (simplified from

Saucedo and others, 2000)

Cenozoic volcanic rocks

Cenozoic sediment deposits

Mesozoic granitic rocks

Mesozoic and Paleozoic metamorphic,

ultramafic, and sedimentary rocks

Hydrogeologic province boundary (Belitz and

others, 2003)

Geomorphic province boundary within the Cascade

Range and Modoc Plateau hydrogeologic province

(California Geological Survey, 2002)

County boundary 
Hydrogeologic Setting 7

Figure 2.—Continued

CAMP_fig2b.ai

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006 

Albers Equal Area Conic Projection

North American Datum of 1983 (NAD 83)

Klamath River

Lower Klamath

Lake

Tule

Lake

Goose

Lake

Upper

Alkali

Lake

Middle

Alkali

Lake

Lower

Alkali

Lake

Middle

Alkali

Lake

Lower

Alkali

Lake

Lake

Shasta

Lake

Oroville

Eagle

Lake

Honey

Lake

Clear Lake

Reservoir

Goose

Lake

Upper

Alkali

Lake

Clear Lake

Reservoir

Pit River

6-4*

6-1*

6-2

5-4*

1-3*

5-5*

1-2.01*

1-2.02

5-2.02*

5-2.01*

1-4*

6-100 (6-103)

(5-55)

5-1

5-35*

6-94

6-3

5-46*

6-101

5-1

5-50*

6-96

5-7*

6-92

5-3

1-18

1-17

(5-34)

(5-33) 5-36

6-95

6-99

5-54

5-43

6-91

5-52

6-98

5-53

6-93

5-86

5-47

5-41

5-37

5-51

5-49

5-40

5-48

5-38

6-97

5-45

5-44

6-101

Pit River

Klamath River

Lower Klamath

Lake

Tule Klamath

Lake

River

122° 121° 120°

5-8

42°

41°

40°

Yreka

Burney

Redding

Alturas

Susanville

Mount Shasta

Yreka

Burney

Redding

Alturas

Susanville

Mount Shasta

Lake

Almanor

Lake

Shasta

Sacramento R.Sacramento R.

(B)

0 10 20 MILES

0 10 20 KILOMETERS

LAVA BEDS

NATIONAL

MONUMENT

LASSEN VOLCANIC

NATIONAL

PARK

Feather RiverFeather River

Tulakeelake

Chico

(1-24)

1-22
8 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Figure 2.—Continued

EXPLANATION

Basin no.

5-34

5-55

5-33

1-24

6-103

Discontinued basin name

Mount Shasta Volcanic Area

Sacramento Valley Eastside Tuscan Formation Highlands

Modoc Plateau Pleistocene Volcanic Areas

Modoc Plateau Pleistocene Volcanic Areas

Modoc Plateau Pleistocene Volcanic Areas

Basin no.

6-4

1-4

1-2.01

1-3

5-2.01

5-2.02

5-4

5-5

5-7

5-35

5-46

5-50

6-1

HL

SH

LU

LU

LU

LU

LU

LU

LU

LU

LU

LU

LU

CDWR, 2004a

CDWR, 2004b

CDWR, 2004c

CDWR, 2004d

CDWR, 2004e

CDWR, 2004f

CDWR, 2004g

CDWR, 2004h

CDWR, 2004i

CDWR, 2004j

CDWR, 2004k

CDWR, 2004l

CDWR, 2004m

Basin name Study area Reference

Honey Lake Valley

Shasta Valley

Upper Klamath basinTule Lake subbasin

Butte Valley

Alturas basin, South Fork

Pit River subbasin

Alturas basin, Warm Springs

Valley subbasin

Big Valley

Fall River Valley

Lake Almanor Valley

McCloud Area

Lake Britton Area

North Battle Creek

Surprise Valley

Basin no.

1-2.02

1-17

1-18

1-22

5-1

5-3

5-8

5-36

5-37

5-38

5-40

5-41

Basin name

Upper Klamath basin - Lower

Klamath Lake subbasin

Bray Town Area

Red Rock Valley

Fairchild Swamp Area

Goose Lake

Jess Valley

Mountain Meadows Valley

Round Valley

Toad Well Area

Pondosa Town Area

Hot Springs Valley

Egg Lake Valley

Basin no.

5-43

5-44

5-45

5-47

5-48

5-49

5-51

5-52

5-53

5-54

5-86

6-2

Basin name

Rock Prairie Valley

Long Valley

Clayton Valley

Goose Valley

Burney Creek Area

Dry Burney Creek Valley

Butte Creek Valley

Grays Valley

Dixie Valley

Ash Valley

Joseph Creek

Madeline Plains

Basin no.

6-3

6-91

6-92

6-93

6-94

6-95

6-96

6-97

6-98

6-99

6-100

6-101

Basin name

Willow Creek Valley

Cow Head Lake Valley

Pine Creek Valley

Harvey Valley

Grasshopper Valley

Dry Valley

Eagle Lake Area

Horse Lake Valley

Tuledad Canyon Valley

Painters Flat

Secret Valley

Bull Flat

Volcanic groundwater basins defined by CDWR (1980)

and discontinued in CDWR (2003)

Other areas in the Cascade

Range and Modoc Plateau 

hydrogeologic province

Other hydrogeologic provinces

National monument and park

County boundary

CDWR-defined groundwater basins that contain CDPH wells

CDWR-defined groundwater basins that do not contain CDPH wells

(5-55)

6-4*

6-2
Hydrogeologic Setting 9

The central and eastern parts of the CAMP study unit 

are in the Modoc Plateau. The Modoc Plateau is the northern 

extension of the Walker Lane belt, a 100–300-km-wide 

zone of distributed late Cenozoic dextral strike-slip and 

normal faulting between the Sierra Nevada and the Basin 

and Range provinces (Friends of the Pleistocene, 1995; 

Oldow and Cashman, 2009). The Modoc Plateau is covered 

with volcanic rocks, primarily basalt and basaltic andesite 

lava flows, ranging in age from late Miocene to Holocene 

(approximately 15 Ma to present). Locally, there are also 

pyroclastic deposits and more silicic volcanic features. 

Fault‐bounded basins within the Modoc Plateau are filled with 

late Miocene to Holocene alluvial, pyroclastic, and lacustrine 

sediments. The Honey Lake and Surprise Valley basins on the 

California-Nevada State line generally are considered Basin 

and Range basins, and the Honey Lake and Surprise Valley 

Faults are major faults in the region. 

The CAMP study unit was divided into six study 

areas (fig. 3). The aquifer systems in the six study areas are 

geologically different. The objective of dividing the study 

unit into study areas was to evaluate potential differences 

in groundwater quality between these geologically distinct 

aquifer systems. Four of the study areas correspond to 

CDWR‐defined groundwater basins, and two correspond to 

mapped geologic units on the State geologic map (Jennings, 

1977; Saucedo and others, 2000).

• CAMP-ES study area: Sacramento Valley Eastside, 

• CAMP-HL study area: Honey Lake Valley groundwater 

basin, 

• CAMP-LU study area: Cascade Range and Modoc 

Plateau Low Use Basins, 

• CAMP-QV study area: Quaternary Volcanic Areas 

mapped as Qv on the State geologic map,

• CAMP-SH study area: Shasta Valley and Mount Shasta 

Volcanic Area, and

• CAMP-TV study area: Tertiary Volcanic Areas mapped 

as Tv on the State geologic map.

Sacramento Valley Eastside Study Area (ES)

The ES corresponds to the former CDWR-defined 

volcanic groundwater basin 5-55, the Sacramento Valley 

Eastside Tuscan Formation Highlands (fig. 2B; California 

Department of Water Resources, 1980). It is no longer 

designated as a CDWR basin because volcanic areas statewide 

were reclassified as groundwater source areas rather than 

basins (California Department of Water Resources, 2003). 

The boundary between the ES study area and the Sacramento 

Valley is defined by the Chico Monocline (fig. 4E), a normal 

fault active within the last 1 Ma moving the Sierra Nevada 

up relative to the Central Valley. East of the Monocline, the 

Tuscan Formation dips less than 5 degrees, and west of the 

Monocline, the Tuscan Formation dips at least 20 degrees, 

disappearing beneath the younger valley sediments (Harwood 

and Helley, 1987). The other boundaries of the ES study 

area are defined by the extent of surface outcrops of the 

Tuscan Formation. 

The Tuscan Formation in the ES study area consists of 

many volcanic mudflows, or lahars. About three-fourths of 

the exposed area is tuff breccia, a massive chaotic assemblage 

of boulder- to pebble-size fragments of andesitic lava in 

a clastic matrix of volcanic ash and fine volcanic debris 

(Lydon, 1968). The Formation grades westward from lahar 

deposits to volcanic sediments, and in the Central Valley, the 

Tuscan Formation sediments are a significant aquifer. The 

lahars erupted approximately 3 Ma from vents on the flanks 

of now-extinct volcanoes in areas west and south of Lassen 

Volcanic National Park, and form a unit up to 1,700 ft thick 

(Lydon, 1968).

Wells in the ES study area are completed in the Tuscan 

Formation. The tuff breccia is less permeable than the 

volcanic sediments, resulting in variable well yields. Several 

communities in the southern part of the ES study area have 

had to rely on drinking water brought in by tanker trucks 

(California Department of Water Resources, 2003).

Honey Lake Valley Study Area (HL)

The HL study area corresponds to the CDWR-defined 

Honey Lake Valley groundwater basin (fig. 2B; CDWR basin 

number 6-4; California Department of Water Resources, 

2004a). The Honey Lake Valley is a topographically closed 

basin that is geologically part of the Basin and Range. The 

basin is bounded on the south by the Honey Lake Fault, which 

separates it from the Mesozoic granitic rocks of the Sierra 

Nevada, and on the other sides by Quaternary and Tertiary 

lava flows (fig. 4F).

The Honey Lake Valley is a down-faulted basin 

containing up to 6,000 ft of Pliocene to Holocene (5 Ma to 

present) sediments with interbedded lava flows and pyroclastic 

deposits (California Department of Water Resources, 1963; 

Handman and others, 1990). The primary water-bearing 

units are the Pleistocene to Holocene lacustrine and alluvial 

sediments. Honey Lake was on the western edge of glacial 

Lake Lahontan, a large lake that covered most of northwestern 

Nevada during the last glacial period. Near-shore deposits 

from this large lake are relatively coarse-grained and highly 

permeable, and are an important source of groundwater to 

wells. Pleistocene volcanic rocks interbedded with the lake 

sediments on the north side of the basin act as conduits for 

groundwater recharge of the basin.
10 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Figure 3. Boundaries of the six study areas in the Cascade Range and Modoc Plateau (CAMP) study unit, California GAMA Priority 

Basin Project, boundaries of study area buffers, and locations of wells in the California Department of Public Health database and wells 

sampled for this study.

sac12-0457_fig 03.ai

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006 

Albers Equal Area Conic Projection

North American Datum of 1983 (NAD 83)

Other areas in the Cascade

Range and Modoc Plateau 

hydrogeologic province

Other hydrogeologic provinces

National monument and park

"

"

"

"

"

"

"

"

97

395

395

89

299

99

70

36

44

139

139

USGS grid well

Other CDPH well

Study area buffers

County boundary

EXPLANATION

Study areas

Sacramento Valley Eastside (ES)

Honey Lake Valley (HL)

Shasta Valley and Mount Shasta

Volcanic Area (SH)

Cascade Range and Modoc Plateau

Low-Use Basins (LU)

Quaternary Volcanic Areas (QV)

Tertiary Volcanic Area (TV)

0 10 20 MILES

0 10 20 KILOMETERS

Fig. 4b

Fig. 4d

Fig. 4c

Fig. 4e

Fig. 4f

Fig. 4a Fig. 4b

5

122° 121° 120°

42°

41°

40°
Hydrogeologic Setting 11

Figure 4. The (A) northwestern, (B) north-central, (C) northeastern, (D) west-central, (E) southwestern, and (F) southeastern parts of 

the Cascade Range and Modoc Plateau (CAMP) study unit, California GAMA Priority Basin Project, boundaries of study areas and study 

area buffers, and locations of selected hydrologic and geologic features, wells sampled for this study, and other wells in the California 

Department of Public Health (CDPH) database.

sac12-0457_fig4a.ai

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006 

Albers Equal Area Conic Projection

North American Datum of 1983 (NAD 83)

Fault (Saucedo and others, 2000)

County boundary

Dam

USGS grid well and identifier

Other CDPH well

Study area buffer and cells

"

"

"

"

"

TV-15 TV-01

SH-15

SH-14

SH-13

SH-12

SH-12

SH-11

SH-10

SH-09

SH-08

SH-07

SH-06

SH-05

SH-04

SH-03

SH-02

SH-01

SISKIYOU CO

TRINITY CO

Weed

Yreka Montague

Dunsmuir unsmuir

Parks Creek

Klamath River

Willow

Creek

Little Shasta River

Trinity River

Shasta River

SH-15

SH-13

SH-12

SH-11

SH-10

SH-09

SH-01

SISKIYOU CO

Yreka Montague

Little Shasta River

Shasta River

Sacramento River

Klamath River

96

89

IRON GATE DAM

Copco Lake

TV-15

Klamath River

Klamath River

IRON GATE DAM

Copco Lake

Mount Shasta

Mount Shasta City

SH-14

SH-08

SH-07

SH-06

SH-05

SH-04

SH-03

SH-02

TRINITY CO

Weed

Parks Creek

Willow

Creek

Trinity River

Sacramento River

Mount Shasta

Mount Shasta City

97

(A)

0 5 10 MILES

0 5 10 KILOMETERS

EXPLANATION

Study areas

Shasta Valley and Mount Shasta

Volcanic Area (SH)

Quaternary Volcanic Areas (QV)

Tertiary Volcanic Areas (TV)

Other areas in the Cascade Range

and Modoc Plateau Province

Other hydrogeologic provinces 

5

Lake

Shastina

122°30' 122°15'

41°45'

41°30'

41°15'
12 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Figure 4.—Continued

sac12-0457_fig4b.ai

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006 

Albers Equal Area Conic Projection

North American Datum of 1983 (NAD 83)

"

"

"

"

QV-04

QV-02

QV-01

LU-10

LU-08

LU-07

LU-02

LU-01

SISKIYOU CO

MODOC CO

Dorris

McCloud

Macdoel

Tulelake

122°15' 122° 121°45' 121°30'

41°45'

41°30'

41°15' 89

139

97

Ash Creek

McCloud River

QV-02

QV-01

LU-08

SISKIYOU CO

McCloud

Ash Creek

McCloud River

LU-10 QV-04

LU-07

LU-02

LU-01

MODOC CO

Dorris

Macdoel

Tulelake Lost River

(B)

0 5 10 MILES

0 5 10 KILOMETERS

Meiss

Lake

Lower

Klamath

Lake Tule

Lake

Meiss

Lake

Lower

Klamath

Lake Tule

Lake

LAVA BEDS

NATIONAL

MONUMENT

Fault (Saucedo and others, 2000)

County boundary

USGS grid well and identifier

Other CDPH well

Study area buffers

!

LU-08

EXPLANATION

Study areas

Shasta Valley and Mount Shasta

Volcanic Area (SH)

Cascade Range and Modoc

Plateau Low Use Basins (LU)

Quaternary Volcanic Areas (QV)

Tertiary Volcanic Areas (TV)

Other areas in the Cascade Range

and Modoc Plateau Province

Other hydrogeologic provinces

National monument and park 

Medicine Lake

Highlands
Hydrogeologic Setting 13

Figure 4.—Continued

sac12-0457_fig4c.ai

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006. 

Albers Equal Area Conic Projection

North American Datum of 1983 (NAD 83)

"

"

"

"

TV-07

QV-03

LU-11

LU-09 LU-06

LU-05

LU-04

LU-03

MODOC CO

LASSEN CO

Canby

Likely

Alturas

Cedarville

Warner

Mountains

121° 120°45' 120°30' 120°15'

41°30'

41°15'

139

139

299

299

395

395

Canby

Alturas

Cedarville

MODOC CO

TV-07

QV-03

LU-11

LU-09 LU-06

LU-05

LU-04

LU-03

Likely

LASSEN CO

Pit Riv er

Ash

Creek

Mill Creek

Pine Creek

South Fork Pit River

Willow Creek

East Creek

North Fork Pit RiverNorth Fork Pit River

Fitzhugh CreekFitzhugh Creek

Cedar Creek Cedar 

Big Sage

Reservoir

Middle Alkali

Lake

Pit Riv er

Pine Creek

Big Sage

Reservoir

Middle Alkali

Lake

Lower Alkali

Lake

Ash

Creek

Mill Creek

South Fork Pit River

Willow Creek

East Creek

Cedar Creek Cedar Creek

Lower Alkali

Lake

Moon

Lake

Warner

Mountains

(C)

0 5 10 MILES

0 5 10 KILOMETERS

EXPLANATION

Study areas

Cascade Range and Modoc

Plateau Low Use Basins (LU)

Quaternary Volcanic Areas (QV)

Tertiary Volcanic Areas (TV)

Other areas in the Cascade Range

and Modoc Plateau Province

Other hydrogeologic provinces 

SURPRISE FAULT

Fault (Saucedo and others, 2000)

County boundary

USGS grid well and identifier

Other CDPH well

Study area buffer and cells

!

TV-07
14 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Figure 4.—Continued

sac12-0457_fig4d.ai

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006 

Albers Equal Area Conic Projection

North American Datum of 1983 (NAD 83)

EXPLANATION

Study areas

Sacramento Valley 

Eastside (ES)

Cascade Range and Modoc

Plateau Low Use Basins (LU)

Quaternary Volcanic Areas (QV)

Tertiary Volcanic Areas (TV)

Other areas in the Cascade Range

and Modoc Plateau Province

Other hydrogeologic provinces

National monument and park 

"

"

"

"

122° 121°45' 121°30' 121°15'

41°

40°45'

40°30'

TV-14 TV-11

TV-05

TV-04

TV-03

TV-02

QV-15

QV-13

QV-12

QV-11

QV-10

QV-08

QV-07

QV-05

LU-13

LU-12

QV-15

QV-13

QV-12

QV-11

QV-10

LU-12

LASSEN VOLCANIC

NATIONAL

PARK

299

89

89

44

Burney

Shingletown

Manzanita Lake

Fall River Mills

SHASTA CO

LASSEN CO

TEHAMA CO EHAMA CO PLUMAS CO LUMAS CO

LASSEN VOLCANIC

NATIONAL

PARK

Pit

Fall

River

River

Pit River

TV-14 TV-11

TV-02

QV-08

QV-07

QV-05

Burney

SHASTA CO

Pit River

Hat

TV-05

TV-04

Fall River Mills

LASSEN CO Hat Creek

Shingletown

Manzanita Lake

89

(D)

Fall River

0 5 10 MILES

0 5 10 KILOMETERS

Fault (Saucedo and others, 2000)

County boundary

USGS grid well and identifier

Other CDPH well

Study area buffer and cells

!

QV-13
Hydrogeologic Setting 15

Figure 4.—Continued

CAMP_fig4e.ai

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006 

Albers Equal Area Conic Projection

North American Datum of 1983 (NAD 83)

"

"

"

"

Spanish

Creek

Middle Fork Feather River

Fall

North Fork Feather River

Spanish

Creek

Middle Fork Feather River

Fall

 

South Fork

Feather River

South Fork

Feather River

North Fork Feather River

River

Chico Monocline

TV-13

TV-12

TV-10

TV-09

QV-14 TV-06 QV-09 LU-15

LU-14

ES-15

ES-14

ES-13

ES-12

TV-13

TV-12

ES-11

ES-10

ES-09

ES-08

ES-07

ES-06

ES-05

ES-04

ES-03

ES-08

ES-07

ES-02

ES-01

PLUMAS CO

BUTTE CO

TEHAMA CO

LASSEN CO

SIERRA CO IERRA CO

Chico

Magalia

Chester

TV-10

TV-09

QV-14 TV-06 QV-09 LU-15

LU-14

PLUMAS CO

TEHAMA CO

LASSEN CO Chester

Paradise ES-15

ES-14

ES-11

ES-09 ES-06

ES-05

ES-04

ES-02

ES-01

BUTTE CO

Chico

Magalia

Paradise

121°45' 121°30' 121°15' 121°

40°15'

40°0'

39°45'

EXPLANATION

Study areas

Sacramento Valley Eastside (ES)

Cascade Range and Modoc

Plateau Low Use Basins (LU)

Quaternary Volcanic Areas (QV)

Tertiary Volcanic Areas (TV)

Other areas in the Cascade Range

and Modoc Plateau Province

Other hydrogeologic provinces

National monument and park 

36

Lake

Almanor

Lake

Oroville

70 99

Mill Creek

Butte Creek

Deer Creek

Big

Chico Creek

Mud Creek

Butt Creek

Rock Cree

P

k

ine Creek

Big Dry Creek

Paynes Creek

South Fork Battle Creek

Singer Creek

North Fork Antelope Creek

Little Dry

Creek

Philbrook Creek

Mill Creek

Butte Creek

Deer Creek

Big

Chico Creek

Mud Creek

Butt Creek

Rock Cree

P

k

ine Creek

Big Dry Creek

Paynes Creek

South Fork Battle Creek

Singer Creek

North Fork Antelope Creek

Little Dry

Creek

Philbrook Creek

River

(E)

0 5 10 MILES

0 5 10 KILOMETERS

Fault (Saucedo and others, 2000)

County boundary

USGS grid well and identifier

Other CDPH well

Study area buffer and cells

ES-04
16 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Figure 4.—Continued

sac12-0457_fig4f.ai

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006 

Albers Equal Area Conic Projection

North American Datum of 1983 (NAD 83)

"

"

Honey Lake oney Lake

Eagle

Lake

TV-08

QV-06

HL-15

HL-14

HL-13

HL-12

HL-11

HL-10

HL-09

HL-08

HL-07

HL-06

HL-05

HL-04

HL-03

HL-02

HL-01

TV-08

QV-06

HL-15

HL-14

HL-13

HL-12

HL-11

HL-10

HL-09

HL-08

HL-07

HL-06

HL-05

HL-04

HL-03

HL-02

HL-01

Honey Lake Fault

LASSEN CO

PLUMAS CO

LASSEN CO

PLUMAS CO Herlong

Susanville

Herlong

Susanville

EXPLANATION

Study areas

Cascade Range and Modoc

Plateau Low Use Basins (LU)

Quaternary Volcanic Areas (QV)

Tertiary Volcanic Areas (TV)

Honey Lake Valley (HL)

Other areas in the Cascade Range

and Modoc Plateau Province

Other hydrogeologic provinces 

120°45' 120°30' 120°15' 120°

40°45'

40°30'

40°15'

40°

395

395

139

Susan River

Willow Creek

Indian Creek

Last Chance Creek

Pete Creek

Smoke Creek

Secret Creek

DeepCreek

Long Valley Creek

Balls Canyon

Bull Creek

Rush Creek

Susan River

Willow Creek

Indian Creek

Last Chance Creek

Pete Creek

Smoke Creek

Secret Creek

DeepCreek

Long Valley Creek

Balls Canyon

Bull Creek

Rush Creek

36

(F)

0 5 10 MILES

0 5 10 KILOMETERS

Fault (Saucedo and others, 2000)

County boundary

USGS grid well and identifier

Other CDPH well

Study area buffer and cells

HL-12
Hydrogeologic Setting 17

More than 40 intermittent and perennial streams flow into 

the valley and terminate at Honey Lake. However, the amount 

of groundwater recharge is low because about 90 percent 

of the total precipitation and stream inflow to the basin is 

lost by evapotranspiration (Handman and others, 1990). The 

sources of groundwater recharge are direct infiltration of 

precipitation at higher elevations in the watershed, infiltration 

of streamflow on alluvial fans on the valley margins, and 

infiltration of irrigation return water. In addition, upwelling 

of thermal waters along the faults bounding the basin may 

contribute up to 40 percent of recharge locally (Mayo and 

others, 2010). Faults within the basin limit lateral groundwater 

flow (Rose and others, 1997). Groundwater discharge is by 

evapotranspiration and by pumping. Most of the groundwater 

extraction is for irrigation, although geothermal waters 

associated with the faults bounding the basin are extracted 

for power generation (Lassen County Board of Supervisors, 

2007). Groundwater levels have declined in parts of the basin 

due to pumping.

Shasta Valley and Mount Shasta Volcanic Area 

Study Area (SH)

The SH study area corresponds to the CDWR-defined 

Shasta Valley groundwater basin (CDWR basin number 

1-4; California Department of Water Resources, 2004b) and 

former CDWR-defined volcanic groundwater basin 5-34, the 

Mount Shasta Volcanic Area (California Department of Water 

Resources, 1980) (figs. 2B, 4A). The CDWR Shasta Valley 

groundwater basin is defined by Quaternary alluvial deposits 

up to 140 ft thick along the western and northern sides of 

Shasta Valley. However, the groundwater basin appears to 

be hydrologically continuous with the volcanic rocks of the 

Mount Shasta Volcanic Area (Mack, 1960).

Most of the SH study area consists of the Mount Shasta 

Volcanic Area. Approximately two-thirds of the Valley is 

covered by a debris-avalanche that fell from Mount Shasta 

between 300,000 and 380,000 years ago (Crandell, 1989). 

The avalanche deposits are up to 300 ft thick and consist of 

two facies: a block facies containing blocks of andesite lava 

flows and volcaniclastic deposits up to many hundreds of 

feet in maximum dimension, and a matrix facies consisting 

of an unsorted, unstratified mix of boulders through clay-size 

material, primarily from andesite lava flows and material 

scoured from the valley floor. The principal aquifer in the 

valley is the Holocene Pluto’s Cave basalt lava flow from 

Mount Shasta (Mack, 1960; California Department of Water 

Resources, 2004b). This basalt is exposed on the surface in the 

southeastern part of the study unit. 

The Shasta River is listed as impaired under the Clean 

Water Act due to elevated stream temperatures and low 

dissolved oxygen levels that have a detrimental effect on fish 

populations, and the river has a total maximum daily load 

(TMDL) action plan (North Coast Regional Water Quality 

Control Board, 2006). The source of cold flows in the Shasta 

River is inflow from groundwater and spring discharges. 

Groundwater pumping, primarily for agricultural uses, has 

become a contentious issue in the valley because pumping 

may decrease spring discharge and increase the depth to the 

water table.

Groundwater recharge is mostly by infiltration of 

streamflow and snowmelt into permeable lava flows, 

dominantly in the southern part of the valley on the slopes 

of Mount Shasta. Much of the valley floor receives less 

than 15 in/yr of precipitation, thus direct infiltration from 

precipitation is minimal. Some groundwater recharge occurs 

by percolation of irrigation water and seepage of water 

behind impoundments. Groundwater discharge is by seepage 

to streams (Shasta River empties into the Klamath River), 

pumping, and evapotranspiration.

Cascade Range and Modoc Plateau Low Use 

Basins Study Area (LU)

The LU study area includes 47 CDWR-defined 

groundwater basins (fig. 2B). Of these 47 basins, 11 contain 

wells listed in the CDPH database of wells used for public 

drinking-water supply. Hydrologic features of those 11 basins 

are discussed briefly here.

The Tule Lake subbasin of the Upper Klamath River 

groundwater basin is bounded on the east and west by 

north-south trending normal faults, on the south by Pleistocene 

and Holocene lava flows of the Medicine Lake volcano, and 

on the north by the Oregon State line (figs. 2B, 4B; CDWR 

basin number 1-2.01; California Department of Water 

Resources, 2004c). The subbasin is filled with Pliocene to 

Holocene lacustrine deposits that have low permeability and 

interbedded Miocene, Pliocene, and Pleistocene basalt lava 

flows. The principal aquifer is highly permeable Miocene/

Pliocene basalt lava flows beneath the lake sediments. In 2001, 

ten deep irrigation wells were drilled into this aquifer and 

have yields ranging from 4,000 to 12,000 gallons per minute 

(gal/min). Recharge to the subbasin occurs primarily by 

subsurface flow through permeable basalt lava flows that are 

exposed in the highlands north and east of the subbasin, and 

by subsurface flow from the adjacent Lower Klamath Lake 

subbasin (Gannett and others, 2007).

The surface-water hydrology of the subbasin has 

been extensively modified as part of the U.S. Bureau of 

Reclamation Klamath Project (Gannett and others, 2007). 

Prior to the Klamath Project, Tule Lake was much larger, 

surrounded by vast wetlands, and fed by the Lost River. 

Hydraulic head gradients suggest that the lake drains in the 

subsurface southward through the Medicine Lake Highlands 

towards the Pit River (Gannett and others, 2007). The Lost 

River is now connected to the Klamath River by a manmade canal, and much of the subbasin has been drained 

for agricultural use. The existing Tule Lake Sump collects 

irrigation return water that is then pumped out of the basin into 

Lower Klamath Lake. The subbasin is extensively irrigated 
18 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

with surface water from Upper Klamath Lake (in Oregon). 

Pumpage of groundwater has increased dramatically since 

2001, largely due to the use of groundwater to augment 

surface-water supplies to help maintain fish populations 

(National Research Council, 2008).

Butte Valley is a closed basin within the Klamath 

River watershed. The basin was formed by faulting and is 

defined by the surface extent of alluvial fill (figs. 2B, 4B; 

CDWR basin number 1-3; California Department of Water 

Resources, 2004d). The main aquifer units are coarse-grained 

lake deposits and interbedded volcanic units, particularly 

the Butte Valley Basalt in the southeastern part of the basin 

(Planert and Williams, 1995). Major sources of groundwater 

recharge include subsurface flow in volcanic units, percolation 

of precipitation and streamflow, and irrigation return water. 

Major sources of groundwater discharge include subsurface 

flow in volcanic units, pumping for agriculture, municipal, and 

environmental uses, and evapotranspiration.

The South Fork Pit River and Warm Springs Valley 

subbasins of the Alturas area are defined by surface exposure 

of Holocene alluvial deposits and the Plio-Pleistocene Alturas 

Formation (figs. 2B, 4C; CDWR basin numbers 5-2.01 and 

5-2.02; California Department of Water Resources, 2004e,f). 

The basins are surrounded by Quaternary and Tertiary lava 

flows and are separated by surface exposure of the PlioPleistocene Warm Springs Tuff. The basins are dissected by 

many northwest-southwest–trending faults, and the Alturas 

Formation is folded into three synclines with northwestsouthwest–trending axes (California Department of Water 

Resources, 1963). These structures affect groundwater flow in 

the basin. The Warm Springs subbasin has hot springs located 

on faults that permit deep circulation of groundwater. The 

main water-bearing units in the basins are permeable beds of 

tuff, ashy sandstone, and diatomite in the lacustrine Alturas 

Formation. Basalt lava flows which are exposed around the 

basins and also are interbedded with the Alturas Formation 

serve as primary recharge areas. 

The boundaries of the Big Valley groundwater basin are 

defined by the surface extent of Holocene alluvial deposits and 

the Pleistocene Bieber Formation, and the basin is surrounded 

by Pliocene (TV) and Pleistocene (QV) lava flows (figs. 2B, 

4C; CDWR basin number 5-4; California Department of 

Water Resources, 2004g). The Pit River flows through the 

western side of the valley. The principal water-bearing units 

are pumiceous sand and volcanic sand layers in the lacustrine 

Bieber Formation. 

The Fall River Valley is defined by surface exposure of 

Pleistocene and Holocene alluvial and lacustrine deposits, 

and is surrounded by Pliocene, Pleistocene, and Holocene 

volcanic rocks (figs. 2B, 4D; CDWR basin number 5-5; 

California Department of Water Resources, 2004h). The 

Fall River Springs, which are among the largest springs in 

the United States at 1,400 to 2,000 cubic feet per second 

(ft3/s) of discharge (Meinzer, 1927), discharge into the valley 

from the north and provide most of the base flow for the 

surface-water features in the valley. The source of the water 

for the springs appears to be precipitation on the vast Medicine 

Lake Highlands 60 kilometers (km) to the north (Rose and 

others, 1996).

The Lake Almanor Valley groundwater basin is located 

on the northwest shore of Lake Almanor (figs. 2B, 4E; CDWR 

basin number 5-7; California Department of Water Resources, 

2004i). The basin consists of Quaternary alluvial and 

lacustrine deposits and is bounded by Pliocene volcanic rocks. 

The North Fork of the Feather River, which is the southern 

drainage for the highlands in the Lassen area, passes through 

the valley and provides 50 percent of the inflow to Lake 

Almanor (Plumas County Flood Control and Conservation 

District, 2007). Another 25 percent comes from submerged 

springs in the Pliocene volcanic rocks. The lake is a reservoir 

operated for power generation by Pacific Gas & Electric.

The McCloud Area groundwater basin is located on the 

southeast slope of Mount Shasta between approximately 3,000 

and 6,000 ft above mean sea level (figs. 2B, 4B; CDWR basin 

number 5-35; California Department of Water Resources, 

2004j). The basin is defined by the surface extent of a thin 

veneer of mostly Holocene alluvial and glacial deposits. 

The basin is underlain and bounded on the north and east by 

Pliocene and Pleistocene volcanic rocks, and bounded on the 

south by Paleozoic metasedimentary deposits of the Klamath 

Mountains. The area has many springs.

The Lake Britton Area groundwater basin is located 

where Hat Creek joins the Pit River (figs. 2B, 4D; CDWR 

basin number 5-46; California Department of Water 

Resources, 2004k). The basin is defined by the surface extent 

of Holocene alluvial deposits and is surrounded and underlain 

by Pliocene (TV study area) and Pleistocene (QV study area) 

lava flows. 

The North Fork Battle Creek Valley groundwater basin is 

located just west of Lassen Volcanic National Park (figs. 2B, 

4D; CDWR basin number 5-50; California Department of 

Water Resources, 2004l). The basin is defined by the surface 

extent of Holocene alluvial deposits and is surrounded and 

underlain by Pliocene (TV study area) and Pleistocene 

(QV study area) lava flows. These alluvial deposits are 

approximately 32 ft thick and overlie a succession of lava 

flows. The main water-bearing unit is the interbedded layer of 

sand, gravel, ash, and cinder between the lava flows.

The Surprise Valley groundwater basin is located on 

the northeastern edge of the study unit (figs. 2B, 4C; CDWR 

basin number 6-1; California Department of Water Resources, 

2004m). The long, narrow basin is a graben bounded on 

all sides by normal faults. The Surprise Valley fault is the 

westernmost large-offset normal fault in the northwestern 

Basin and Range, and there has been more than 4.5 km of 

vertical offset between the Warner Mountains and the Surprise 

Valley in the last 14 Ma (Egger and Miller, 2011). The valley 

is filled with more than 5,000 ft of alluvial and lacustrine 

deposits, most of which are lacustrine sediments from 

Pleistocene Lake Surprise.
Methods 19

The Surprise Valley is a closed basin. Streams entering 

the valley, primarily from the Warner Mountains to the west, 

terminate in the three seasonal, shallow, saline lakes along the 

central axis of the valley. The primary source of groundwater 

recharge is infiltration of surface water through alluvial fans 

along the base of the Warner Mountains and through coarse 

stream deposits at the northern end of the valley (California 

Department of Water Resources, 1963). The principal aquifers 

are the Holocene alluvial fans and near-shore deposits from 

Pleistocene Lake Surprise. Groundwater discharge is by 

evapotranspiration and pumping, primarily for agricultural 

uses. The Surprise Valley has numerous hot springs associated 

with the Surprise Valley and other faults, and heated 

groundwater is extracted for geothermal power generation.

Quaternary Volcanic Areas (QV) and Tertiary 

Volcanic Areas (TV) Study Areas

The QV and TV study areas consist of areas on the State 

geologic map (Saucedo and others, 2000) that are mapped as 

Quaternary volcanic rocks (Qv) and Tertiary volcanic rocks 

(Tv), respectively (fig. 3). The QV study area includes the 

former CDWR-defined volcanic groundwater basins 5-33, 

1-24, and 6-103, which are the Modoc Plateau Pleistocene 

Volcanic Areas (fig. 2B; California Department of Water 

Resources, 1980). The former CDWR-defined volcanic 

groundwater basins 5-32, 1-23, and 6-102, the Modoc Plateau 

Recent Volcanic Areas, are mapped as Holocene volcanic 

rocks (Qrv) on the State geologic map and are not included in 

the QV study area. The QV and TV study areas each include 

both Cascade Range and Modoc Plateau volcanic rocks. 

Mount Shasta and Medicine Lake Volcano are composed 

of Quaternary and Holocene volcanic rocks, and thus are 

partially included in the QV study area (figs. 4A, 4B). Most of 

Lassen Volcanic National Park is in the QV study area, some 

is in the TV study area, and a small sliver is Holocene volcanic 

rocks (fig. 4D). 

The QV and TV study areas were defined as separate 

areas in order to examine potential relations between 

groundwater quality and age of the aquifer materials. The 

basalt and basaltic andesite lava flows that compose most of 

the QV and TV study areas undergo changes in mineralogy 

with time. Primary igneous minerals and volcanic glass may 

be oxidized and hydrated, and new minerals may be deposited 

in voids. These differences in aquifer mineralogy may result in 

differences in groundwater composition and water quality.

Groundwater in volcanic rocks primarily is contained 

in fractures, tuff beds, rubble zones at the tops of lava flows, 

volcanic pipes, and interbedded sand layers. The distribution 

of permeable zones is unpredictable, although the probability 

of large groundwater yields generally is greater in areas 

near fault zones (Planert and Williams, 1995). Well yields 

commonly vary from 100 to 1,000 gal/min, and yields as high 

as 4,000 gal/min have been measured. The younger volcanic 

rocks generally are more permeable because secondary 

mineralization from hydrothermal alteration tends to lower 

permeability in older volcanic rocks. Volcanic aquifer units 

in the Upper Klamath River basin generally have higher 

and more variable transmissivity than sedimentary units, 

with aquifer tests in volcanic rocks yielding values from 

2,700 to 610,000 feet squared per day (ft2/d) (Gannett and 

others, 2007).

Groundwater recharge in the QV and TV study areas 

is by infiltration of precipitation, particularly in the upland 

areas, and capture of streamflow. Because the volcanic units 

are highly permeable and have little soil or sediment on top 

of them, surface streams and groundwater interchange easily: 

streams disappear into the ground and reappear as spring 

discharge downstream. The CAMP study unit contains a 

number of first magnitude springs, springs with discharge 

greater than 100 ft3/s (Meinzer, 1927). For example, five 

springs discharging in the QV study area near where Hat 

Creek joins the Pit River (fig. 4D) have a combined discharge 

of more than 700 ft3/s, and isotopic data indicate the recharge 

area was 50 km to the south in the high elevations in Lassen 

Volcanic National Park (Rose and others, 1996).

Methods 

Methods used for the GAMA PBP were selected to 

achieve the following objectives: (1) design a sampling plan 

for suitable statistical representation; (2) collect samples in 

a consistent manner; (3) analyze samples 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 and analytical 

methods, the QA plan, and the results of analyses of QC 

samples.

Study Design

The wells sampled in this study were selected by using 

a spatially distributed, randomized grid-based approach 

(Scott, 1990). For most GAMA PBP study units, a set of 

grid cells is generated within each study area by dividing the 

study area into equal-area grid cells. One well in each cell is 

then randomly selected for sampling. However, the CAMP 

study unit contains a relatively low density of CDPH wells 

compared to most other study units, and these wells are not 

evenly distributed across the study unit (fig. 3). If the study 

areas were divided into equal-area cells, it is likely that many 

cells would not contain any wells. As in previous GAMA PBP 

study units with few and (or) unevenly distributed CDPH 

wells, the subset of each study area representing the portion 

of the groundwater resource used for public drinking-water 

supply is identified, and only those subset areas are included 

in the grid cells (for example, Fram and Belitz, 2007). The 
20 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

portion of the groundwater resource used for public drinkingwater supply was defined by delineating 3-km radius circles 

around the locations of wells in the CDPH database (3-km 

buffers). The total area within these 3-km buffers was then 

divided into equal-area grid cells.

The six study areas in the CAMP study unit have total 

areas ranging from 878 km2 to 10,985 km2, and buffered areas 

ranging from 287 km2 to 711 km2 (table 1). The buffered areas 

for each study area were divided into 15 equal-area grid cells. 

The sizes of the grid cells range from 19 km2 in the ES study 

area to 47 km2 in the QV study area. The randomized gridbased method divides the buffered area into equal-area grid 

cells; however, geographic features may force a grid cell to be 

divided into multiple pieces to obtain the designated coverage 

area for each cell. For instance, a portion of a grid cell may be 

located on either side of a mountain range, but the grid cell is 

still considered to be one grid cell. The average size of grid 

cells (25 km2) in the CAMP study unit is similar to the design 

objective for grid-cell size in areas of the State outside of the 

Central Valley (Belitz and others, 2003). 

The objective was to sample one CDPH well in each 

grid cell. If a cell contained more than one CDPH well, each 

well was randomly assigned a rank. The highest ranking well 

that was accessible for sampling and for which permission 

to sample could be obtained was sampled. If a grid cell 

contained a well sampled for the GAMA California Aquifer 

Susceptibility project in 2003 (Moran and others, 2005), then 

that well was promoted to the highest ranking well. If a grid 

cell contained no accessible CDPH wells, then other types of 

wells, such as domestic wells, irrigation, and (or) industrial, 

were considered for sampling. These “alternative” wells were 

identified from wells listed in USGS databases or by doorto-door canvassing. Wells with depths and screened intervals 

similar to those in CDPH wells in the area were selected. In 

this fashion, one well was selected in each cell to provide a 

spatially distributed, randomized monitoring network of 90 

USGS-grid wells. 

One well was sampled in each of the 90 grid cells in the 

CAMP study unit. The wells were given GAMA identification 

numbers consisting of the prefix “CAMP,” followed by a 

second prefix indicating the study area [ES (fig. 4E), HL 

(fig. 4F), LU (figs. 4B–E), QV (figs. 4B–F), SH (fig. 4A), or 

TV (figs. 4A, C–F], followed by a suffix numbered in the order 

of sample collection within each study area. For ease of use, 

the prefix “CAMP” is dropped from the maps presented in 

this report.

Approximately 8 percent of the wells listed in the CDPH 

database for the CAMP study unit were springs; however, 

this may be a minimum estimate of the percentage of springs. 

Springs are sites where groundwater naturally flows from 

below ground to above land surface, sometimes through a 

horizontal well bore. In the CDPH database, a spring with a 

horizontal well bore may be given a name that identifies it as 

a well. All sites are referred to as wells in this report, unless 

the difference between a well and a spring is important to 

the discussion. 

The GAMA alphanumeric identification number for 

each well, along with the date sampled, elevation of well site, 

well type, and available well-construction information, is 

shown in table 2. Groundwater samples were collected from 

81 production wells (74 CDPH wells, 6 domestic wells, and 

1 irrigation well) and 9 springs (8 CDPH springs and 1 spring 

used for irrigation) during the time period from July 12 

through October 14, 2010. 

Well locations were verified 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 or 

other sources of construction information were obtained 

when available. Well information and location were recorded 

by hand on field sheets and electronically on field laptop 

computers using the Alternate Place Entry Form (APE) 

program designed by the USGS. All information was verified 

and then uploaded into the USGS National Water Information 

System (NWIS). Well owner, well use, and well location 

information is confidential.

Sample Collection and Analysis

Samples were collected in accordance with the protocols 

established by the USGS National Water-Quality Assessment 

(NAWQA) Program (Koterba and others, 1995) and the USGS 

National Field Manual (U.S. Geological Survey, variously 

dated). These sampling protocols are followed so that 

representative samples of groundwater are collected at each 

site and so that the samples are collected and handled in ways 

that minimize the potential for contamination.

All 90 USGS-grid wells in the CAMP study unit were 

sampled for the same classes of constituents (table 3). 

Tables 4A–J list the compounds analyzed in each constituent 

class. Groundwater samples were analyzed for 85 volatile 

organic compounds (VOCs; table 4A); 63 pesticides and 

pesticide degradates (table 4B); 1 constituent of special 

interest (table 4C); 5 nutrients (table 4D); 24 trace elements 

(table 4E); total dissolved solids (TDS) and 10 major ions 

(table 4F); 7 radioactive constituents, including tritium 

(table 4G); species of iron and arsenic (table 4H); 5 dissolved 

noble gases, helium stable isotopic ratios, 5 isotope ratios of 

water and dissolved constituents, and carbon-14 abundance 

(table 4I); and 2 microbial indicators (table 4J). The methods 

used for sample collection and analysis are described in the 

appendix section titled “Sample Collection and Analysis.”
Water-Quality Results 21

Data Reporting

The methods and conventions used for reporting the data 

are described in the appendix section titled “Data Reporting.” 

Three field water-quality indicators—alkalinity, pH, and 

specific conductance—were measured in the field and at the 

USGS National Water Quality Laboratory (NWQL), and 

both results are reported (see the appendix section titled 

“Constituents on Multiple Analytical Schedules”). Arsenic 

(total) and iron (total) were measured at the USGS NWQL and 

at the USGS Trace Metal Laboratory (TML), and both results 

are reported. 

Quality Assurance 

The QA/QC procedures used for this study followed 

the protocols used by the USGS NAWQA Program (Koterba 

and others, 1995) and described in the USGS National Field 

Manual (U.S. Geological Survey, variously dated). The QA 

plan followed by the USGS 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 CAMP study unit are as follows: blanks, replicates, 

matrix spikes, and surrogates. 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-Control Methods and 

Results.”

Water-Quality Results 

Quality-Control Results

Results of QC analyses (blanks, replicates, matrix spikes, 

and surrogates) were used to evaluate the quality of the data 

for the groundwater samples. On the basis of detections 

in field blanks collected for this and previous GAMA PBP 

study units, the reporting levels for several volatile organic 

compounds and trace elements were raised to higher 

concentrations than those used by the laboratory. Detections 

of 10 trace elements with low concentrations below the 

raised reporting limits are flagged with a less-than or equal-to 

symbol (≤) in this report. All detections of two VOCs were at 

concentrations below the raised reporting limits; these data are 

presented as non-detections in this report (see table A3 and 

additional discussion in the appendix section titled “Detections 

in Field Blanks and Application of SRLs”). Results from the 

replicates confirm that the procedures used to collect and 

analyze the samples were consistent. Variability was within the 

acceptable limits for greater than 99 percent of the replicate 

pairs for constituents detected in samples (tables A4A–C). 

Median matrix-spike recoveries were within acceptable 

limits for 134 of the 148 organic constituents analyzed; 

13 constituents had recoveries lower than the acceptable 

limit (tables 4B and A5B). Low matrix-spike recoveries may 

indicate that the pesticides and pesticide degradates for which 

low recoveries occurred might not have been detected in some 

samples if they were present in the samples at concentrations 

near the laboratory reporting levels (LRLs). The QC results 

are described in the appendix section titled “Other QualityControl Results.”

Comparison Benchmarks

Concentrations of constituents detected in groundwater 

samples were compared with CDPH and USEPA regulatory 

and nonregulatory drinking-water health-based benchmarks 

and benchmarks established for aesthetic purposes 

(California Department of Public Health, 2010, 2011a; U.S. 

Environmental Protection Agency, 1999, 2009, 2011). The 

chemical data presented in this report are meant to characterize 

the quality of the untreated groundwater within the primary 

aquifer system of the CAMP 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. The following 

benchmarks were used for comparisons:

• 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, 

and individual states may choose to set more stringent 

standards. The CDPH has established MCLs for 

additional constituents not regulated by the USEPA 

and has lowered the benchmark concentration for a 

number of constituents with MCLs established by the 

USEPA. In this report, a benchmark set by the USEPA 

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

and one set by the CDPH that is more stringent 

than the MCL-US is labeled “MCL-CA.” Well 

owners are notified when constituents are detected 

at concentrations greater than MCL-US or MCL-CA 

benchmarks in samples collected for the GAMA PBP, 

but these detections do not constitute violations of 

CDPH regulations.
22 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

• 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.

• TT–Treatment Technique. Legally enforceable 

standards that apply to public water systems and 

are designed to protect public health by limiting the 

levels of microbial constituents in drinking water. 

TT requirements are applied when water delivered to 

consumers exceeds specified action levels. Detections 

of microbial constituents greater than benchmarks 

trigger requirements for mandatory additional 

disinfection during water treatment. The action levels 

established by the USEPA and CDPH are the same; 

thus, these benchmarks are labeled “TT-US” in 

this report.

• 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 the 

USEPA. SMCLs established by the CDPH are used in 

this report (SMCL-CA) for all constituents that have 

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

because no SMCL-CA has been defined.

• NL–Notification Level. Health-based notification 

levels established by CDPH for some of the 

constituents in drinking water that lack MCLs 

(NL-CA). 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.

• 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 

(2.1 quarts) of 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.

• 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 10–5. 

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

10 (RSD5-US).

For constituents with MCLs, detections in groundwater 

samples were compared with the MCL-US or MCL-CA. 

The legally enforceable standards AL-US and TT-US 

were included in the same category as MCLs for the 

purpose of comparison between standards and detections 

in groundwater samples. Constituents with SMCLs were 

compared with the 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 values for these constituents correspond to 

the recommended SMCL-CAs. Detected concentrations of 

constituents without an MCL or an SMCL were compared 

with the NL-CA. For constituents without an MCL, SMCL, 

or NL-CA, detected concentrations were compared with the 

HAL-US. For constituents without an MCL, SMCL, NL-CA, 

or HAL-US, detected concentrations were compared with 

the RSD5-US. Note that using this hierarchy to select the 

comparison benchmark for a constituent with more than one 

type of established benchmark will not necessarily result in 

selection of the benchmark with the lowest concentration. For 

example, for zinc the SMCL-CA is 5,000 micrograms per liter 

(μg/L) and the HAL-US is 2,000 μg/L, but the comparison 

benchmark selected by this hierarchy is the SMCL-CA. 

The comparison benchmarks used in this report are listed 

in tables 4A–J for all constituents and in tables 5–17 for 

constituents detected in groundwater samples from the CAMP 

study unit. Established benchmarks are not available for all 

constituents analyzed for this study. Detections of constituents 

at concentrations greater than the selected comparison 

benchmark are marked with asterisks in tables 5, 9–15. 

Groundwater-Quality Data

Results from analyses of untreated groundwater samples 

from the CAMP study unit are presented in tables 5–17. 

These results are separated into the six study areas that make 

up the CAMP study unit (ES, HL, LU, QV, SH, and TV). 

Groundwater samples collected in the CAMP study unit were 

analyzed for 221 constituents; 121 of those constituents were 

not detected in any of the samples, and 100 constituents were 

detected (table 4A–J). Results for isotopic ratios of boron and 

strontium and results for dissolved noble gases and tritium 

from LLNL are not presented in this report; they will be 

included in a subsequent publication. 
Water-Quality Results 23

For organic and special-interest (perchlorate) constituent 

classes, the results tables list only those wells at which 

constituents were detected and include the following summary 

statistics: the number of wells in the study unit or study area 

at which each analyte was detected, the frequency at which 

it was detected (in relation to the number of grid wells in the 

study unit or study area), and the total number of constituents 

detected at each well. For the inorganic and tracer constituent 

classes, the results tables list all wells sampled and all 

constituents analyzed. For the microbial indicators, the table 

lists only those wells at which detections occurred. 

Water-quality indicators measured in the field and at the 

NWQL are included in table 5. The results of groundwater 

analyses organized by constituent classes are presented in 

tables 6–17: 

Organic and special-interest constituents

• VOCs (table 6)

• Pesticides and pesticide degradates (table 7)

• Perchlorate (table 8)

Inorganic constituents

• Nutrients (table 9)

• Trace elements (table 10)

• Major and minor ions and TDS (table 11)

• Uranium activity (table 12)

• Radon-222 activity (table 13)

• Gross alpha and gross beta particle activity (table 14)

Geochemical and age-dating tracers

• Species of arsenic and iron (table 15)

• Stable isotopes, tritium, and carbon-14 (table 16)

Microbial constituents

• Microbial indicators (table 17)

Water-Quality Indicators 

Field measurements of dissolved oxygen and water 

temperature, and field and laboratory measurements of pH, 

specific conductance, and alkalinity are presented in table 5. 

Bicarbonate and carbonate concentrations are calculated from 

the pH and alkalinity results (see appendix). Dissolved oxygen 

and alkalinity are used as indicators of natural processes that 

affect water chemistry. The pH value indicates the acidity of 

the water. Specific conductance is the measure of electrical 

conductivity of the water and is proportional to the amount of 

total dissolved solids in the water. 

Field pH values were outside of the SMCL-US range for 

20 percent of the CAMP study-unit grid well samples. Fifteen 

well samples had field pH values less than 6.5, and three well 

samples had field pH values greater than 8.5 (table 5). Low pH 

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

water may contribute to scaling. Laboratory pH values may 

differ from field pH values because the pH of groundwater 

may change upon removal from the ambient environment and 

exposure to the atmosphere.

Field specific-conductance values were greater than the 

recommended SMCL-CA of 900 microsiemens per centimeter 

(μS/cm) for 7 of the 90 grid well samples (table 5). The field 

specific-conductance value in one TV study area grid well was 

also greater than the upper benchmark of 1,600 microsiemens 

per centimeter at 25 degrees Celsius (μS/cm at 25 ̊C).

Organic and Special-Interest Constituents

Volatile Organic Compounds (VOCs)

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, 18 were detected in the CAMP 

study-unit groundwater samples; all detections in samples 

were less than health-based benchmarks (table 6). One or 

more VOCs were detected in 27 of the 90 CAMP study-unit 

grid well samples (about 30 percent detection frequency). 

The trihalomethane chloroform was detected in more than 

10 percent of the samples. Chloroform is a byproduct of 

drinking-water disinfection and is the most commonly 

detected VOCs in groundwater nationally (Zogorski and 

others, 2006).

The six study areas of the CAMP study unit had different 

detection frequencies of VOCs. Four VOCs had detection 

frequencies greater than 10 percent in at least one study area. 

The detection frequency of chloroform was greater than 

10 percent in the ES, HL, SH, and TV study areas (table 5). 

Perchloroethene (PCE), a solvent primarily used for drycleaning and metal-degreasing applications, was detected 

in more than 10 percent of the samples from the ES and HL 

study areas. Another solvent, 1,1-dichloroethene (1,1-DCE), 

also was detected in more than 10 percent of the samples from 

the HL study area. The detection frequency of the gasoline 

oxygenate methyl tert-butyl ether (MTBE) was greater than 

10 percent in the SH study area. 
24 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Pesticides

Pesticides include herbicides, insecticides, and fungicides 

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

pests in agricultural, urban, and suburban settings. Of the 

63 pesticides and pesticide degradates analyzed, 9 were 

detected in groundwater samples; all detections were less than 

health-based benchmarks (table 7). One or more pesticides 

or pesticide degradates were detected in 28 of the 90 CAMP 

study-unit grid well samples (about 31 percent detection 

frequency). The herbicide atrazine and its degradation product 

deethylatrazine were detected in more than 10 percent of the 

samples. Atrazine and deethylatrazine are among the nation’s 

most commonly detected pesticide compounds in groundwater 

(Gilliom and others, 2006). 

The six study areas of the CAMP study unit had different 

detection frequencies of pesticides. Five pesticides or pesticide 

degradates had detection frequencies greater than 10 percent in 

at least one study area: deethylatrazine (HL, LU, SH, and TV); 

atrazine (HL, SH, and TV); the herbicide hexazinone (QV, 

SH, and TV); and the herbicides simazine and prometon (SH) 

(table 7). No pesticide or pesticide degradate was detected in 

any of the 15 grid well samples in the ES study area in the 

CAMP study unit.

Perchlorate

Perchlorate is a constituent of special interest in 

California because recent advances in analytical methods 

have resulted in detections of low concentrations in water 

supplies in many parts of the State (California Department 

of Public Health, 2011b). California established an MCL-CA 

for perchlorate in 2007. Perchlorate was detected in 40 of 

the 84 grid wells (47 percent) from which samples were 

collected, and all detections had concentrations less than the 

MCL-CA (table 8). 

Inorganic Constituents

Unlike the organic constituents, inorganic constituents 

generally are naturally present in groundwater, although 

their concentrations may be influenced by human activities. 

Inorganic constituents were sampled for at all 90 grid wells in 

the CAMP study unit. 

Nutrients

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. High concentrations of nitrate or nitrite 

can adversely affect human health, particularly the health 

of infants. 

All concentrations of ammonia and nitrite measured in 

the 90 CAMP study-unit grid wells were less than healthbased benchmarks. For samples from the CAMP study unit, 

the measured nitrite plus nitrate concentration is equal to 

the nitrate concentration because all detections of nitrite 

had concentrations less than the reporting level for nitrite 

plus nitrate (table 9). Nitrate was detected at a concentration 

greater than the MCL-US of 10 milligrams per liter (mg/L), as 

nitrogen, in one HL study area grid well sample (table 9). 

Trace Elements

Seventeen of the 24 trace elements and one of the 

major ions analyzed and detected in the CAMP study unit 

have regulatory or non-regulatory health-based benchmarks 

(tables 4E, F). Of these 18 constituents with health-based 

benchmarks, five constituents were detected at concentrations 

greater than benchmarks: arsenic, boron, molybdenum, 

uranium, and vanadium (table 10). Detections of trace 

elements at concentrations greater than benchmarks occurred 

in at least one sample from the HL, SH, and TV study areas. 

Trace elements were not detected at concentrations greater 

than health-based benchmarks in the ES, LU, and QV study 

area well samples (table 10). 

Arsenic concentrations greater than the MCL-US of 

10 μg/L were detected in two HL study area grid well samples 

and one SH study area grid well sample (table 10). Boron 

concentrations greater than the NL-CA of 1,000 μg/L were 

detected in two TV study area grid well samples (table 10). 

Molybdenum concentrations greater than the HAL-US of 

40 μg/L were detected in one HL and one TV study area grid 

well sample (table 10). Vanadium concentrations greater than 

the NL-CA of 50 μg/L were detected in one HL and one SH 

study area grid well sample (table 10). 

Uranium and 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 of 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). Radium-226, radium-228, and radon-222 

are radioactive isotopes 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 particle, a beta particle, and (or) a gamma ray 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.
Water-Quality Results 25

Activity often is used instead of concentration for 

reporting the presence of radioactive constituents. Activity of 

radioactive 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. 

Twenty grid well samples from the CAMP study 

unit were analyzed for uranium isotopes (uranium-234, 

uranium-235, and uranium-238). Uranium isotope activities 

for two HL study area grid well samples were greater than 

the MCL-CA of 20 pCi/L (table 12). Uranium concentrations 

in these two samples were also greater than the MCL-US 

benchmark of 30 μg/L (table 10).

Samples from all 90 grid wells in the CAMP study unit 

were analyzed for radon-222. Radon-222 activity was greater 

than the proposed MCL-US of 4,000 pCi/L in one HL study 

area grid well (table 13). The proposed MCL-US applies if 

the state or local water agency has an approved multimedia 

mitigation program to address radon levels in indoor air (U.S. 

Environmental Protection Agency, 1999). 

Samples from all 90 grid wells in the CAMP study 

unit were analyzed for gross alpha and gross beta particle 

activities; activities for almost all grid well samples were 

less than established health-based benchmarks. Gross 

alpha particle activity was detected in two HL study area 

grid well samples at activities greater than the MCL-US of 

15 pCi/L (table 14).

Inorganic Constituents with SMCL Benchmarks

The levels of certain trace elements, major-ion 

composition, and total dissolved solids (TDS) content in 

groundwater affect the aesthetic properties of water, such as 

taste, color, and odor, and the technical properties of water, 

such as scaling and staining. Although there are no adverse 

health effects directly associated with these properties, they 

may reduce consumer satisfaction with the water or may 

have economic effects. The CDPH has established nonenforceable benchmarks (SMCL-CAs) that are based on 

aesthetic properties 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 four grid well samples in the 

CAMP study unit—one from each of the ES and HL study 

areas and two from the LU study area (table 10). Manganese 

concentrations greater than the SMCL-CA of 50 μg/L were 

detected in nine grid well samples—four from the HL study 

area, two each from the LU and QV study areas, and one from 

the SH study area (table 10). Silver, zinc, and sulfate were not 

detected at concentrations greater than the SMCL-CAs in any 

of wells in the CAMP study unit.

TDS concentration was greater than the upper SMCL-CA 

of 1,000 mg/L in one TV study area grid well sample 

(table 11). This sample also had a chloride concentration 

greater than the upper SMCL-CA of 500 mg/L. Six HL, 

one LU, one QV, and two SH study area grid well samples 

had TDS concentrations between the recommended and 

upper SMCL-CAs. 

Geochemical and Age-Dating Tracers

Arsenic and iron occur as different species depending on 

the oxidation-reduction state of the groundwater. The oxidized 

and reduced species have different solubilities in groundwater 

and may have different effects on human health. The relative 

proportions of the oxidized and reduced species of each 

element can be used to aid in interpretation of the oxidationreduction conditions of the aquifer, which affect the mobility 

of many constituents. 

Concentrations of total dissolved arsenic and iron 

and the dissolved concentrations of the reduced species of 

the elements are reported in table 15. The concentrations 

of the other species can be calculated by difference. The 

concentrations of total dissolved arsenic and iron reported 

in table 10 are considered to be more accurate than the 

concentrations reported in table 15 (see the appendix section 

titled “Constituents on Multiple Analytical Schedules”). 

The isotopic ratios of water and dissolved constituents, 

indicators of groundwater age, and the concentrations of 

dissolved noble gases may be used as tracers of hydrologic 

processes (Clark and Fritz, 1997). The isotopic ratios 

of hydrogen and oxygen in water (table 16) aid in the 

interpretation of the sources of groundwater recharge. 

These stable isotopic ratios reflect the altitude, latitude, and 

temperature of precipitation and also the extent of evaporation 

of the water in surface-water bodies or soils prior to infiltration 

into the aquifer. 

Tritium activities and carbon-14 abundance (table 16) 

also 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 after the 

early 1950s. Helium isotope ratios are used in conjunction 

with tritium concentrations to estimate ages for young 

groundwater. Helium isotope ratio analyses were not 

completed in time for inclusion in this report; results will be 

presented in a subsequent publication.

Carbon-14 is a radioactive isotope of carbon. 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 
26 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

dioxide dissolves in precipitation, surface water, and 

groundwater exposed to the atmosphere, thereby entering the 

hydrologic cycle. Because carbon-14 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. 

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 recharge water. 

Dissolved noble gas analyses were not completed in time 

for inclusion in this report; results will be presented in a 

subsequent publication.

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 CAMP study-unit 

grid well samples were less than 1/100 of the MCL-CA 

benchmark (table 16). 

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 not available. 

Measurements are made of more easily analyzed microbial 

constituents that serve as indicators of the presence of human 

or animal waste in water. Drinking-water purveyors respond 

to detections of microbial indicators by applying additional 

disinfection agents to the water.

The presence of the microbial indicator total coliform 

was detected in 9 of the 83 grid wells (11 percent) sampled for 

analysis of microbial indicators in the CAMP study unit: one 

groundwater sample from each of the ES, HL, QV, and TV 

study areas; two samples from the LU study area, and three 

samples from the SH study area (table 17). The presence of 

E. coli was also detected in the same TV grid well sample. 

The health-based benchmarks for microbial indicators are 

based on recurring detections in treated drinking water, thus, 

the detections reported here do not constitute a violation of 

the benchmarks.

Future Work

Subsequent reports will be focused on assessment of the 

data presented in this report by using a variety of statistical, 

qualitative, and quantitative approaches to evaluate the 

natural and human factors affecting groundwater quality in 

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

CDPH databases will be compiled, evaluated, and used in 

combination with the data that are presented in this report. 

Additionally, these subsequent reports will include the 

dissolved noble gas, LLNL tritium, and helium isotope ratio 

results for the CAMP study unit.

Summary 

Groundwater quality in the 39,000-square-kilometer 

Cascade Range and Modoc Plateau (CAMP) study unit was 

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

July through October 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 created 

as a result of the Groundwater Quality Monitoring Act of 

2001 to assess and monitor the quality of groundwater and to 

provide a comprehensive baseline of groundwater quality in 

California. The GAMA PBP is being conducted by the USGS 

in cooperation with the SWRCB and Lawrence Livermore 

National Laboratory (LLNL).

The GAMA CAMP study unit was designed to provide 

a spatially unbiased assessment of untreated-groundwater 

quality within the primary aquifer system and to facilitate 

statistically consistent comparisons of untreated-groundwater 

quality throughout California. The primary aquifer system 

is defined as the depth interval of the wells listed in the 

California Department of Public Health (CDPH) database for 

the CAMP study unit. The quality of groundwater in shallow 

or deep water-bearing zones may differ from that in the 

primary aquifer system; shallow groundwater may be more 

vulnerable to surficial contamination.

This study did not attempt to 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. Regulatory 

benchmarks apply to treated water that is served 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 nonregulatory health-based benchmarks 

established by the U.S. Environmental Protection Agency 

(USEPA) and California Department of Public Health (CDPH) 

and with nonregulatory benchmarks established for aesthetic 

concerns by the CDPH.

The CAMP study unit is located within the Cascade 

Range and Modoc Plateau hydrogeologic province and 

includes 55 groundwater basins and subbasins defined by the 

California Department of Water Resources. The study unit also 

includes areas outside of the defined groundwater basins. The 

CAMP study included assessment of groundwater quality for 

samples from 90 wells and springs in Butte, Lassen, Modoc, 

Plumas, Shasta, Siskiyou, and Tehama Counties. All sites 

are referred to as wells in this report, unless the difference 

between a well and a spring is important to the discussion. 
References Cited 27

Wells were selected using a randomized grid approach to 

achieve a statistically unbiased representation of groundwater 

used for public drinking-water supplies (grid wells). Fifteen 

grid wells were sampled in each of the six study areas that 

compose the CAMP study unit: Sacramento Valley Eastside 

(ES), Honey Lake Valley (HL), Cascade Range and Modoc 

Plateau Low Use Basins (LU), Quaternary Volcanic Areas 

(QV), Shasta Valley and Mount Shasta Volcanic Area (SH), 

and Tertiary Volcanic Areas (TV).

Groundwater samples were analyzed for field 

water-quality indicators, organic constituents, perchlorate, 

inorganic constituents, radioactive constituents, and microbial 

indicators. Naturally occurring isotopes and dissolved noble 

gases also were measured to provide a dataset that will be 

used to help interpret the sources and ages of the sampled 

groundwater in subsequent reports. In total, 221 constituents 

were investigated for this study. 

All organic constituents and most inorganic constituents 

that were detected in groundwater samples from the 90 grid 

wells in the CAMP study unit were detected at concentrations 

less than drinking-water benchmarks. 

Of the 148 organic constituents analyzed, 27 were 

detected in groundwater samples; concentrations of 

all detected constituents were less than regulatory and 

nonregulatory health-based benchmarks. One or more organic 

constituents were detected at concentrations less than 1/10 of 

benchmark levels in 52 percent of the grid wells in the CAMP 

study unit: VOCs were detected in 30 percent, and pesticides 

and pesticide degradates were detected in 31 percent. 

Most of the samples analyzed for inorganic and 

radioactive constituents had concentrations or activities 

less than the regulatory and the nonregulatory health-based 

benchmarks. All samples from the ES, LU, and QV study 

areas had concentrations of inorganic constituents and 

activities of radioactive constituents less than the regulatory 

and the nonregulatory health-based benchmarks. Arsenic was 

detected at concentrations greater than the USEPA maximum 

contaminant level (MCL-US) in samples from two wells in the 

HL study area and one well in the SH study area. Boron was 

detected at concentrations greater than the CDPH notification 

level (NL-CA) in samples from two wells in the TV study 

area. Molybdenum was detected at concentrations greater 

than the USEPA lifetime health advisory level (HAL-US) in 

samples from one well in the HL study area and one well in 

the TV study area. Vanadium was detected at concentrations 

greater than the NL-CA in samples from one well in the HL 

study area and one well in the SH study area. Uranium was 

detected at concentrations greater than the MCL-US and at 

activities greater than the CDPH maximum contaminant level 

(MCL-CA) in two wells from the HL study area. These HL 

study area samples also had gross alpha particle activities 

greater than the MCL-US. Radon was detected at activities 

greater than the proposed MCL-US in a sample from one well 

in the HL study area. Nitrate was detected at a concentration 

greater than the MCL-US in a sample from one well in the HL 

study area.

Most of the samples analyzed for inorganic constituents 

had concentrations less than the non-enforceable benchmarks 

set for aesthetic concerns (CDPH secondary maximum 

contaminant levels, SMCL-CA). Manganese was detected at 

concentrations greater than the SMCL-CA in samples from a 

total of nine wells in the HL, LU, QV, and SH study areas, and 

iron was detected at concentrations greater than the SMCL-CA 

in samples from a total of four wells in the ES, HL, and LU 

study areas. Total dissolved solids (TDS) and chloride were 

detected at concentrations greater than their respective upper 

SMCL-CAs in one well from the TV study area. Samples from 

a total of 10 wells in the HL, LU, QV, and SH study areas 

had concentrations of TDS between the recommended and 

upper SMCL-CAs.

Microbial indicator (total coliform and Escherichia coli 

[E. coli]) samples were collected from 83 grid wells. Total 

coliform was detected in 9 of the 83 grid wells (1 from each 

of the ES, HL, QV, and TV study areas, 2 from the LU study 

area, and 3 from the SH study area). E. coli was also detected 

in the same grid well sample from the TV study area in which 

total coliform was detected. 

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 well owners and 

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

collect samples from their wells.

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36 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

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Tables 37

Tables
38 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table 1. Study area names, study area and grid cell sizes, and numbers of CDPH wells and USGS-grid wells in each study area, 

Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.

[CDPH, California Department of Public Health; USGS, U.S. Geological Survey; km2, square kilometers]

Study area Code Area

(km2

)

Buffered 

area

(km2

)

Cell area 

(km2

)

Number of 

CDPH wells

Number of 

USGS-grid 

wells

Sacramento Valley Eastside CAMP-ES 2,004 287 19 33 15

Honey Lake Valley CAMP-HL 1,261 270 18 50 15

Cascade Range and Modoc Plateau Low Use Basins CAMP-LU 4,826 510 34 68 15

Quaternary Volcanic Areas CAMP-QV 10,399 711 47 98 15

Shasta Valley and Mount Shasta Volcanic Area CAMP-SH 878 369 25 61 15

Tertiary Volcanic Areas CAMP-TV 10,985 517 34 59 15

Table 2. Identification, sampling, and construction information for wells sampled for the Cascade Range and Modoc Plateau (CAMP) 

study unit, July through October 2010, California GAMA Priority Basin Project. 

[GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range 

and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic 

Area study area grid well; TV, Tertiary Volcanic Areas study area. Other abbreviations: >, greater than; ≥, greater than or equal to; ft, foot; LSD, land surface 

datum; NAVD 88, North American Vertical Datum of 1988; na, not available]

Sampling information Construction information

GAMA well 

identification 

number

Date sampled

(mm-dd-yy) 

Altitude of LSD 

(ft above 

NAVD 88)1

Well type Well depth

(ft below LSD)

Top of open or 

screened interval 

(ft below LSD)

Bottom of open or 

screened interval 

(ft below LSD)

CAMP Sacramento Valley Eastside study area (15 grid wells sampled)

CAMP-ES-01 09-13-10 2,351 Production 400 65 400

CAMP-ES-02 09-13-10 1,686 Production 325 60 325

CAMP-ES-03 09-14-10 2,267 Spring na na na

CAMP-ES-04 09-16-10 383 Production 475 160 475

CAMP-ES-05 09-20-10 1,934 Production 550 395 525

CAMP-ES-06 09-20-10 2,602 Production 930 823 930

CAMP-ES-07 09-21-10 3,089 Production 80 60 80

CAMP-ES-08 10-04-10 3,328 Production 386 346 386

CAMP-ES-09 10-04-10 1,524 Production 730 500 730

CAMP-ES-10 10-05-10 1,520 Production 770 495 760

CAMP-ES-11 10-05-10 2,306 Production 480 440 480

CAMP-ES-12 10-06-10 2,821 Production 995 93 995

CAMP-ES-13 10-06-10 2,054 Production 96 na na

CAMP-ES-14 10-07-10 413 Production 2 > 285 na na

CAMP-ES-15 10-12-10 294 Production 480 206 470

CAMP Honey Lake Valley study area

CAMP-HL-01 08-10-10 4,031 Production 300 50 300

CAMP-HL-02 08-11-10 4,344 Production 240 140 240

CAMP-HL-03 08-11-10 4,144 Production 2 > 180 na na

CAMP-HL-04 08-12-10 4,097 Production 600 55 600

CAMP-HL-05 08-18-10 4,139 Production 190 190 190

CAMP-HL-06 08-18-10 4,106 Production 56 40 56

CAMP-HL-07 08-19-10 4,011 Production 200 60 200

CAMP-HL-08 08-19-10 4,006 Production 208 60 208
Tables 39

Sampling information Construction information

GAMA well 

identification 

number

Date sampled

(mm-dd-yy) 

Altitude of LSD 

(ft above 

NAVD 88)1

Well type Well depth

(ft below LSD)

Top of open or 

screened interval 

(ft below LSD)

Bottom of open or 

screened interval 

(ft below LSD)

CAMP Honey Lake Valley study area—Continued

CAMP-HL-09 08-23-10 4,133 Production 530 220 520

CAMP-HL-10 08-23-10 4,123 Production 545 na na

CAMP-HL-11 08-24-10 4,050 Production 225 165 205

CAMP-HL-12 08-24-10 4,223 Production 246 50 246

CAMP-HL-13 08-31-10 4,474 Production 130 na na

CAMP-HL-14 08-31-10 4,093 Production 102 na na

CAMP-HL-15 09-01-10 4,058 Production 120 110 120

CAMP Cascade Range and Modoc Plateau Low Use Basins study area

CAMP-LU-01 07-19-10 4,247 Production 1,236 840 1,236

CAMP-LU-02 07-19-10 4,038 Production 2,664 2,546 2,664

CAMP-LU-03 07-21-10 4,379 Production 670 350 670

CAMP-LU-04 07-21-10 4,666 Production 353 126 350

CAMP-LU-05 07-22-10 4,391 Production 500 220 500

CAMP-LU-06 07-22-10 4,317 Production 220 180 220

CAMP-LU-07 07-27-10 4,259 Production 87 59 87

CAMP-LU-08 07-29-10 4,184 Spring na na na

CAMP-LU-09 08-02-10 4,400 Production 310 100 310

CAMP-LU-10 08-03-10 4,052 Production 343 100 338

CAMP-LU-11 08-04-10 4,225 Production 184 na na

CAMP-LU-12 08-05-10 4,127 Production 146 54 146

CAMP-LU-13 08-09-10 4,124 Production 3 345 95 110

CAMP-LU-14 08-30-10 4,549 Production 235 162 222

CAMP-LU-15 08-30-10 4,528 Production 371 228 360

CAMP Quaternary Volcanic Areas study area

CAMP-QV-01 07-20-10 6,887 Spring na na na

CAMP-QV-02 07-29-10 4,919 Spring na na na

CAMP-QV-03 08-02-10 5,014 Production 740 400 740

CAMP-QV-04 08-03-10 4,090 Production 325 211 325

CAMP-QV-05 08-09-10 3,200 Production 226 226 226

CAMP-QV-06 08-12-10 4,197 Production 2 ≥ 800 2 800 2 ≥ 800

CAMP-QV-07 08-17-10 3,258 Production 300 250 300

CAMP-QV-08 08-17-10 3,218 Production 244 184 244

CAMP-QV-09 08-25-10 4,985 Spring na na na

CAMP-QV-10 09-13-10 2,260 Production 174 47 174

CAMP-QV-11 09-13-10 3,338 Production 170 110 170

CAMP-QV-12 09-14-10 2,588 Production 232 3 232

CAMP-QV-13 09-14-10 2,957 Production 184 164 184

CAMP-QV-14 09-15-10 4,715 Production 465 240 465

CAMP-QV-15 09-20-10 3,728 Production 150 22 150

Table 2. Identification, sampling, and construction information for wells sampled for the Cascade Range and Modoc Plateau (CAMP) 

study unit, July through October 2010, California GAMA Priority Basin Project.—Continued 

[GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range 

and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic 

Area study area grid well; TV, Tertiary Volcanic Areas study area. Other abbreviations: >, greater than; ≥, greater than or equal to; ft, foot; LSD, land surface 

datum; NAVD 88, North American Vertical Datum of 1988; na, not available]
40 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Sampling information Construction information

GAMA well 

identification 

number

Date sampled

(mm-dd-yy) 

Altitude of LSD 

(ft above 

NAVD 88)1

Well type Well depth

(ft below LSD)

Top of open or 

screened interval 

(ft below LSD)

Bottom of open or 

screened interval 

(ft below LSD)

CAMP Shasta Valley and Mount Shasta Volcanic Area study area

CAMP-SH-01 07-12-10 2,744 Production 120 12 120

CAMP-SH-02 07-13-10 2,952 Production 232 80 232

CAMP-SH-03 07-13-10 2,779 Production 107 na na

CAMP-SH-04 07-14-10 3,721 Production 450 200 450

CAMP-SH-05 07-14-10 3,778 Spring na na na

CAMP-SH-06 07-15-10 3,684 Production 328 288 328

CAMP-SH-07 07-15-10 4,465 Spring na na na

CAMP-SH-08 07-26-10 3,302 Production 2 > 40 na na

CAMP-SH-09 07-27-10 2,576 Production 230 30 225

CAMP-SH-10 07-28-10 2,841 Production 309 132 267

CAMP-SH-11 07-28-10 2,762 Production 6 > 52 52 na

CAMP-SH-12 09-22-10 2,642 Production 150 na na

CAMP-SH-13 09-23-10 2,604 Spring na na na

CAMP-SH-14 10-13-10 3,844 Production 140 120 140

CAMP-SH-15 10-14-10 2,568 Production 4 121 na na

CAMP Tertiary Volcanic Areas study area

CAMP-TV-01 07-12-10 2,690 Production 218 175 218

CAMP-TV-02 08-04-10 2,953 Production 4 > 450 na na

CAMP-TV-03 08-05-10 978 Spring 5 na na na

CAMP-TV-04 08-16-10 3,455 Production 300 na na

CAMP-TV-05 08-16-10 4,266 Production 300 210 290

CAMP-TV-06 08-25-10 4,823 Production 380 305 380

CAMP-TV-07 08-26-10 6,262 Production 230 50 230

CAMP-TV-08 09-01-10 5,173 Production 200 na na

CAMP-TV-09 09-02-10 4,564 Production 403 158 400

CAMP-TV-10 09-02-10 4,551 Production 2 > 300 na na

CAMP-TV-11 09-15-10 3,767 Production 202 87 202

CAMP-TV-12 09-15-10 4,321 Production 210 170 210

CAMP-TV-13 09-16-10 4,220 Production 2 135 na na

CAMP-TV-14 09-21-10 3,284 Production 175 155 170

CAMP-TV-15 10-13-10 2,273 Production 275 54 275

1

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.

2

 Estimated from well owner records; no driller’s log available.

3

 Driller’s log (1978) gives initial well depth as 500 ft; well owner reported video log (2005) showing current depth of 345 ft.

4

 Estimated from measurement of well depth by USGS; no driller’s log available.

5

 Conveyance from the TV-03 spring source to the point of use is an open channel.

6

 Driller’s log (1972) reports installation of sanitary seal to depth of 52 ft in an existing well. Owner reports hole depth and well depth greater than 52 ft.

Table 2. Identification, sampling, and construction information for wells sampled for the Cascade Range and Modoc Plateau (CAMP) 

study unit, July through October 2010, California GAMA Priority Basin Project.—Continued 

[GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range 

and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic 

Area study area grid well; TV, Tertiary Volcanic Areas study area. Other abbreviations: >, greater than; ≥, greater than or equal to; ft, foot; LSD, land surface 

datum; NAVD 88, North American Vertical Datum of 1988; na, not available]
Tables 41

Table 3. Classes of chemical constituents and field water-quality indicators collected for the Cascade Range and Modoc Plateau 

(CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.

Constituent classes Constituent 

list table

Results

table

Field water-quality indicators 

Dissolved oxygen, temperature, pH, and specific conductance 5

Organic and special-interest constituents

Volatile organic compounds (VOC) 4A 6

Pesticides and pesticide degradates 4B 7

Perchlorate 4C 8

Inorganic constituents

Nutrients 4D 9

Trace elements 4E 10

Major and minor ions, silica, and total dissolved solids (TDS) 4F 11

Alkalinity (measured in field and laboratory) 4F 5

Uranium isotopes 4G 12

Radon-222 4G 13

Gross alpha and gross beta particle activities 4G 14

Geochemical and age-dating tracers

Arsenic and iron species 4H 15

Stable isotopes of hydrogen (δ2H) and oxygen (δ18O) of water 4I 16

δ13C of inorganic carbon dissolved in water and carbon-14 abundance 4I 16

δ11B of boron and 87Sr/86Sr of strontium dissolved in water 4I none(1)

Tritium 4G 16

Dissolved noble gases 4I none(1)

Microbial constituents

Escherichia coli (E. coli) and total coliform 4J 17

1

 Results will be presented in a subsequent publication.
42 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program Table 4A. 

Volatile organic compounds (VOCs), primary uses or sources, comparative benchmarks, and reporting information for the U.S. Geological Survey (USGS) National 

Water Quality Laboratory Schedule 2020.[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Benchmark type and benchmark level as of January 10, 2012. 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 Abstract Service; LRL, laboratory reporting level; THM, trihalomethane; D, detected 

in groundwater samples (table 6); na, not available; μg/L, micrograms per liter; –, not detected]

Constituent (synonym or abbreviation) Primary use or source

USGS 

parameter 

code

CAS number 1 LRL (μg/L) 2 Benchmark type Benchmark level (μg/L) Detection

Acetone Solvent 81552 67-64-1 3.4 na na – (3)

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 D

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 5 80 –

Bromoform (Tribromomethane) Disinfection byproduct (THM) 32104 75-25-2 0.1 MCL-US 5 80 –Bromomethane (Methyl bromide) Fumigant 34413 74-83-9 0.2, 0.20 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, 0.060 NL-CA 260 –Carbon disulfide Natural, organic synthesis 77041 75-15-0 0.04, 0.08 NL-CA 160

D

Carbon tetrachloride (Tetrachloromethane) Solvent 32102 56-23-5 0.052, 0.06 MCL-CA 0.5 –

Chlorobenzene Solvent 34301 108-90-7 0.016, 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 5 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 5 80 –1,2-Dibromo-3-chloropropane (DBCP) Fumigant 82625 96-12-8 0.34, 0.40 MCL-US 0.2 –

1,2-Dibromoethane (EDB) Fumigant 77651 106-93-4 0.05, 0.028 MCL-US 0.05 –Dibromomethane Solvent 30217 74-95-3 0.05, 0.050 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 D

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 –

1,1-Dichloroethane (1,1-DCA) Solvent 34496 75-34-3 0.044 MCL-CA 5 –
Tables 43

Constituent (synonym or abbreviation) Primary use or source

USGS 

parameter 

code

CAS number 1 LRL (μg/L) 2 Benchmark type Benchmark level (μg/L) Detection

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 D

cis-1,2-Dichloroethene (cis-1,2-DCE) Solvent 77093 156-59-2 0.022 MCL-CA 6 –

trans-1,2-Dichloroethene (trans-1,2-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 0.03, 0.040 na na –cis-1,3-Dichloropropene Fumigant 34704 10061-01-5 0.1 RSD5-US 6 4 –

trans-1,3-Dichloropropene Fumigant 34699 10061-02-6 0.14 RSD5-US 6 4 –Diethyl ether Solvent 81576 60-29-7 0.08, 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 0.14 na na –2-Ethyltoluene Gasoline hydrocarbon 77220 611-14-3 0.032 na na D

Hexachlorobutadiene Organic synthesis 39702 87-68-3 0.06 RSD5-US 9 –Hexachloroethane Solvent 34396 67-72-1 0.14 HAL-US 1 –2-Hexanone (n-Butyl methyl ketone) Solvent 77103 591-78-6 0.46, 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 D

4-Isopropyltoluene Gasoline hydrocarbon 77356 99-87-6 0.06 na na D

Methyl acrylate Organic synthesis 49991 96-33-3 0.56, 0.8 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 0.038, 0.04 MCL-US 5 D

Table 4A. Volatile organic compounds (VOCs), primary uses or sources, comparative benchmarks, and reporting information for the U.S. Geological Survey (USGS) National 

Water Quality Laboratory Schedule 2020.—Continued

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Benchmark type and benchmark level as of January 10, 2012. 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 Abstract Service; LRL, laboratory reporting level; THM, trihalomethane; D, detected 

in groundwater samples (table 6); na, not available; μg/L, micrograms per liter; –, not detected]
44 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program Table 4A. Volatile organic compounds (VOCs), primary uses or sources, comparative benchmarks, and reporting information for the U.S. Geological Survey (USGS) National Water Quality Laboratory Schedule 2020.—Continued [The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Benchmark type and benchmark level as of January 10, 2012. 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 Abstract Service; LRL, laboratory reporting level; THM, trihalomethane; D, detected in groundwater samples (table 6); na, not available; μg/L, micrograms per liter; –, not detected] Constituent (synonym or abbreviation) Primary use or source USGS parameter code CAS number 1 LRL (μg/L) 2 Benchmark type Benchmark level (μg/L) Detection Methyl ethyl ketone (2-butanone, MEK) Solvent 81595 78-93-3 1.6 HAL-US 4,000 – 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 Gasoline hydrocarbon 77224 103-65-1 0.036 NL-CA 260

D

Styrene Gasoline hydrocarbon 77128 100-42-5 0.03, 0.042 MCL-US 100 –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 1.4 na na – (3)

1,2,3,4-Tetramethylbenzene Gasoline hydrocarbon 49999 488-23-3 0.08, 0.1 na na

D

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

D

Toluene Gasoline hydrocarbon 34010 108-88-3 0.018 MCL-CA 150 – (4)

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, 0.030 MCL-CA 200

D

1,1,2-Trichloroethane (1,1,2-TCA) Solvent 34511 79-00-5 0.046, 0.028 MCL-CA 5 –Trichloroethene (TCE) Solvent 39180 79-01-6 0.022 MCL-US 5 –Trichlorofluoromethane (CFC-11) Refrigerant 34488 75-69-4 0.08 MCL-CA 150 –1,2,3-Trichloropropane (1,2,3-TCP) Fumigant, solvent 77443 96-18-4 0.12 HAL-US 7 40 –

Trichlorotrifluoroethane (CFC-113) Refrigerant 77652 76-13-1 0.034 MCL-CA 1,200

D

1,2,3-Trimethylbenzene Gasoline hydrocarbon 77221 526-73-8 0.06, 0.060 na na

D

1,2,4-Trimethylbenzene Gasoline hydrocarbon 77222 95-63-6 0.032 NL-CA 330 – (4)

1,3,5-Trimethylbenzene Gasoline hydrocarbon 77226 108-67-8 0.032 NL-CA 330

D

Vinyl bromide (Bromoethene) Organic synthesis 50002 593-60-2 0.12 na na –Vinyl chloride (Chloroethene) Organic synthesis 39175 75-01-4 0.06 MCL-CA 0.5 –m- and 

p-Xylene Gasoline hydrocarbon 85795 108-38-3 / 106-42-3 0.08 MCL-CA 8 1,750 –

o-Xylene Gasoline hydrocarbon 77135 95-47-6 0.032 MCL-CA 8 1,750 –
Tables 45

Table 4A. Volatile organic compounds (VOCs), primary uses or sources, comparative benchmarks, and reporting information for the U.S. Geological Survey (USGS) National 

Water Quality Laboratory Schedule 2020.—Continued

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Benchmark type and benchmark level as of January 10, 2012. 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 Abstract Service; LRL, laboratory reporting level; THM, trihalomethane; D, detected 

in groundwater samples (table 6); na, not available; μg/L, micrograms per liter; –, not detected]

Footnotes:

1 This report contains CAS Registry Numbers® (CASRNs), which is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs through CAS Client 

ServicesSM.

2 For constituents with two LRLs listed, the first value was in use before 10/01/2010, and the second value was in use after 10/01/2010. The highest LRL is used for this report. 3 All detections of these constituents were reviewed and rejected (Fram and others, 2012).4 All detections of these constituents in samples from the CAMP study unit had concentrations less than the study reporting levels (SRLs). The SRLs are 0.69 μg/L for toluene and 0.56 μg/L for 

1,2,4-trimethylbenzene (Fram and others, 2012).

5 The MCL-US benchmark for trihalomethanes is the sum of chloroform, bromoform, bromodichloromethane, and dibromochloromethane.6 The RSD5-US benchmark for 1,3-dichloropropene is the sum of its isomers (cis and trans).7 In earlier reports in this series, the NL-CA (0.005 μg/L) was used as the comparison benchmark for 1,2,3-TCP.8 The MCL-CA benchmark for m- and p-Xylene and o-Xylene is the sum of all three xylene compounds.
46 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table 4B. Pesticides and pesticide degradates, primary uses or sources, comparative benchmarks, and reporting information for the 

U.S. Geological Survey (USGS) National Water Quality Laboratory Schedule 2003.

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

level as of January 10, 2012. 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 maximum contaminant level; MCL-US, USEPA maximum contaminant 

level; RSD5-US, USEPA risk specific dose at a risk factor of 10–5. Other abbreviations: CAS, Chemical Abstract Service; LRL, laboratory reporting level; D, 

detected in groundwater samples (table 7); na, not available; μg/L, micrograms per liter; –, not detected]

Constituent Primary use or source

USGS 

parameter 

code

CAS number LRL 

(μg/L) 1

Benchmark 

type

Benchmark 

level 

(μg/L)

Detection

Acetochlor Herbicide 49260 34256-82-1 0.010 na na –

Alachlor Herbicide 46342 15972-60-8 0.008 MCL-US 2 –

Atrazine Herbicide 39632 1912-24-9 0.007, 0.008 MCL-CA 1 D

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

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

Benfluralin Herbicide 82673 1861-40-1 0.014 na na –

Carbaryl Insecticide 82680 63-25-2 0.06 RSD5-US 400 D

2-Chloro-2,6-

diethylacetanilide 

Herbicide degradate 61618 6967-29-9 0.010 na na –

4-Chloro-2-methylphenol Herbicide degradate 61633 1570-64-5 0.0032, 0.0046 na na –

Chlorpyrifos Insecticide 38933 2921-88-2 0.010, 0.036 HAL-US 2 –

Chlorpyrifos oxon Insecticide degradate 61636 5598-15-2 0.05, 0.06 na na – (2)

Cyfluthrin Insecticide 61585 68359-37-5 0.016 na na – (2)

Cypermethrin Insecticide 61586 52315-07-8 0.020 na na – (2)

Dacthal (DCPA) Herbicide 82682 1861-32-1 0.0076 HAL-US 70 –

Deethylatrazine (2-Chloro-4-

isopropylamino-6-amino-striazine)

Herbicide degradate 04040 6190-65-4 0.014, 0.006 na na D

Desulfinylfipronil Insecticide degradate 62170 na 0.012 na na –

Desulfinylfipronil amide Insecticide degradate 62169 na 0.029 na na –

Diazinon Insecticide 39572 333-41-5 0.005, 0.0060 NL-CA 1.2 –

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

Dichlorvos Insecticide 38775 62-73-7 0.02, 0.04 na na – (2)

Dicrotophos Insecticide 38454 141-66-2 0.08 na na – (2)

Dieldrin Insecticide 39381 60-57-1 0.009, 0.008 RSD5-US 0.02 –

2,6-Diethylaniline Herbicide degradate 82660 579-66-8 0.006, 0.0060 na na –

Dimethoate Insecticide 82662 60-51-5 0.006 na na – (2)

Ethion Insecticide 82346 563-12-2 0.008 na na –

Ethion monoxon Insecticide degradate 61644 17356-42-2 0.021 na na –

2-Ethyl-6-methylaniline Herbicide degradate 61620 24549-06-2 0.0098, 0.010 na na –

Fenamiphos Insecticide 61591 22224-92-6 0.030 HAL-US 0.7 –

Fenamiphos sulfone Insecticide degradate 61645 31972-44-8 0.053, 0.054 na na –

Fenamiphos sulfoxide Insecticide degradate 61646 31972-43-7 0.08 na na – (2)

Fipronil Insecticide 62166 120068-37-3 0.018 na na –

Fipronil sulfide Insecticide degradate 62167 120067-83-6 0.013, 0.012 na na –

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

Fonofos Insecticide 04095 944-22-9 0.0044, 0.0048 HAL-US 10 –
Tables 47

Constituent Primary use or source

USGS 

parameter 

code

CAS number LRL 

(μg/L) 1

Benchmark 

type

Benchmark 

level 

(μg/L)

Detection

Hexazinone Herbicide 04025 51235-04-2 0.008 HAL-US 400 D (2)

Iprodione Fungicide 61593 36734-19-7 0.014 na na –

Isofenphos Insecticide 61594 25311-71-1 0.006 na na –

Malaoxon Insecticide degradate 61652 1634-78-2 0.08, 0.022 na na –

Malathion Insecticide 39532 121-75-5 0.016 HAL-US 100 –

Metalaxyl Fungicide 61596 57837-19-1 0.007, 0.014 na na D

Methidathion Insecticide 61598 950-37-8 0.006, 0.012 na na –

Metolachlor Herbicide 39415 51218-45-2 0.014, 0.020 HAL-US 700 –

Metribuzin Herbicide 82630 21087-64-9 0.012 HAL-US 70 –

Myclobutanil Fungicide 61599 88671-89-0 0.010 na na –

1-Naphthol Insecticide degradate 49295 90-15-3 0.036 na na – (2)

Paraoxon-methyl Insecticide degradate 61664 950-35-6 0.010, 0.014 na na –

Parathion-methyl Insecticide 82667 298-00-0 0.008 HAL-US 1 –

Pendimethalin Herbicide 82683 40487-42-1 0.012 na na –

cis-Permethrin Insecticide 82687 54774-45-7 0.014, 0.010 na na – (2)

Phorate Insecticide 82664 298-02-2 0.02, 0.020 na na –

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

Phosmet Insecticide 61601 732-11-6 0.034, 0.14 na na – (2)

Phosmet oxon Insecticide degradate 61668 3735-33-9 0.0511 na na – (2)

Prometon Herbicide 04037 1610-18-0 0.012 HAL-US 100 D

Prometryn Herbicide 04036 7287-19-6 0.006 na na –

Pronamide (Propyzamide) Herbicide 82676 23950-58-5 0.0036 RSD5-US 20 –

Simazine Herbicide 04035 122-34-9 0.006 MCL-US 4 D

Tebuthiuron Herbicide 82670 34014-18-1 0.028 HAL-US 500 D (3)

Terbufos Insecticide 82675 13071-79-9 0.018 HAL-US 0.4 –

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

Terbuthylazine Herbicide 04022 5915-41-3 0.006, 0.0060 na na –

Tribufos Defoliant 61610 78-48-8 0.018 na na – (2)

Trifluralin Herbicide 82661 1582-09-8 0.018 HAL-US 10 –

1

 For constituents with two LRLs listed, the first value was in use before 10/01/2010, and the second value was in use after 10/01/2010. The highest LRL is 

used for this report. 

2

 The median matrix-spike recovery was less than 70 percent. Low recoveries may indicate that the compound might not have been detected in some samples 

if it was present at very low concentrations.

3

 The median matrix-spike recovery was greater than 130 percent. High recoveries may indicate that reported values could be greater than what is in the 

sample.

Table 4B. Pesticides and pesticide degradates, primary uses or sources, comparative benchmarks, and reporting information for the 

U.S. Geological Survey (USGS) National Water Quality Laboratory Schedule 2003.—Continued

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

benchmark level as of January 10, 2012. 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 maximum contaminant level; MCL-US, USEPA maximum contaminant 

level; RSD5-US, USEPA risk specific dose at a risk factor of 10–5. Other abbreviations: CAS, Chemical Abstract Service; LRL, laboratory reporting level; D, 

detected in groundwater samples (table 7); na, not available; μg/L, micrograms per liter; –, not detected]
48 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table 4C. Perchlorate, primary uses or sources, comparative benchmarks, and reporting information for Weck Laboratories, Inc., 

analyses.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Benchmark type and benchmark level as of January 10, 

2012. 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. Other 

abbreviations: USGS, U.S. Geological Survey; CAS, Chemical Abstract Service; MRL, minimum reporting level; μg/L, micrograms per liter D, detected in 

groundwater samples (table 8)] 

Constituent Primary use or source

USGS 

parameter 

code

CAS number MRL 

(μg/L)

Benchmark 

type

Benchmark level 

(μg/L) Detection

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

Table 4D. Nutrients, comparative benchmarks, and reporting information for the U.S. Geological Survey (USGS) National Water 

Quality Laboratory Schedule 2755.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Benchmark type and benchmark level as of January 10, 

2012. 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; CAS, Chemical Abstract Service; LT-MDL, long-term 

method detection level; D, detected in groundwater samples (table 9); na, not available; mg/L, milligrams per liter]

Constituent

USGS

parameter

code

CAS number LT-MDL 

(mg/L) 1

Benchmark 

type

Benchmark

level

(mg/L)

Detection

Ammonia (as nitrogen) 00608 7664-41-7 0.01, 0.010 HAL-US 2 24.7 D

Nitrite (as nitrogen) 00613 14797-65-0 0.001, 0.0010 MCL-US 1 D

Nitrate plus nitrite (as nitrogen) 00631 na 0.02, 0.020 MCL-US 10 D

Total nitrogen (ammonia, 

nitrite, nitrate, organic 

nitrogen)

62854 17778-88-0 0.05 na na D

Phosphate, orthophosphate (as 

phosphorus)

00671 14265-44-2 0.004 na na D

1

 For constituents with two LT-MDLs listed, the first value was in use before 10/01/2010, and the second value was in use after 10/01/2010. The highest 

LT-MDL is used for this report. Nitrite has a method detection level (MDL), rather than an LT-MDL.

2

 The HAL-US is 30 mg/L “as ammonia.” To facilitate comparson to the analytical results, this HAL-US has been converted and reported as 24.7 mg/L “as 

nitrogen.”
Tables 49

Table 4E. Trace elements, comparative benchmarks, and reporting information for the U.S. Geological Survey (USGS) National Water 

Quality Laboratory Schedule 1948.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Benchmark type and benchmark level as of January 10, 

2012. 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: CAS, Chemical Abstract 

Service; LRL, laboratory reporting level; LT-MDL, long-term method detection level; D, detected in groundwater samples (table 10); na, not available; μg/L, 

micrograms per liter]

Constituent

USGS

parameter

code

CAS number LT-MDL 

(μg/L) 1

Benchmark 

type

Benchmark

level

(μg/L)

Detection

Aluminum 01106 7429-90-5 1.7 MCL-CA 1,000 D

Antimony 01095 7440-36-0 0.027 MCL-US 6 D

Arsenic 01000 7440-38-2 0.022 MCL-US 10 D

Barium 01005 7440-39-3 0.07 MCL-CA 1,000 D

Beryllium 01010 7440-41-7 0.006 MCL-US 4 D

Boron 01020 7440-42-8 1.4, 3 NL-CA 1,000 D

Cadmium 01025 7440-43-9 0.01, 0.016 MCL-US 5 D

Chromium 01030 7440-47-3 0.06 MCL-CA 50 D

Cobalt 01035 7440-48-4 0.005, 0.02 na na D

Copper 01040 7440-50-8 0.5 AL-US 1,300 D

Iron 01046 7439-89-6 3, 3.2 SMCL-CA 300 D

Lead 01049 7439-92-1 0.015 AL-US 15 D

Lithium 01130 7439-93-2 0.22 na na D

Manganese 01056 7439-96-5 0.13 SMCL-CA 50 D

Molybdenum 01060 7439-98-7 0.014 HAL-US 40 D

Nickel 01065 7440-02-0 0.06, 0.09 MCL-CA 100 D

Selenium 01145 7782-49-2 0.020, 0.03 MCL-US 50 D

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

Strontium 01080 7440-24-6 0.20, 0.2 HAL-US 4,000 D

Thallium 01057 7440-28-0 0.010 MCL-US 2 D

Tungsten 01155 7440-33-7 0.010 na na D

Uranium 22703 7440-61-1 0.004 MCL-US 30 D

Vanadium 01085 7440-62-2 0.08 NL-CA 50 D

Zinc 01090 7440-66-6 1.4 SMCL-CA2 5,000 D

1

 For constituents with two LT-MDLs listed, the first value was in use before 10/01/2010, and the second value was in use after 10/01/2010. The highest 

LT-MDL is used for this report. 

2

 The secondary maximum contaminant level (SMCL) for zinc is listed as SMCL-CA because SMCLs established by CDPH are used in this report for all 

constituents that have SMCL-CA values.
50 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table 4F. 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 Schedule 1948.

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

level as of January 10, 2012. 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: CAS, Chemical Abstract Service; LT-MDL, long-term 

method detection level; D, detected in groundwater samples (table 11); na, not available; mg/L, milligrams per liter]

Constituent

USGS

parameter

code

CAS 

number

 LT-MDL 

(mg/L) 1

Benchmark 

type

Benchmark

level

(mg/L)

Detection

Bromide 71870 24959-67-9 0.01, 0.010 na na D

Calcium 00915 7440-70-2 0.022 na na D

Chloride 00940 16887-00-6 0.06 SMCL-CA 2 250 (500) D

Fluoride 00950 16984-48-8 0.04 MCL-CA 2 D

Iodide 71865 7553-56-2 0.001, 0.0010 na na D

Magnesium 00925 7439-95-4 0.008 na na D

Potassium 00935 7440-09-7 0.032, 0.022 na na D

Silica (as SiO2) 00955 7631-86-9 0.029 na na D

Sodium 00930 7440-23-5 0.05, 0.06 na na D

Sulfate 00945 14808-79-8 0.09 SMCL-CA 2 250 (500) D

Total dissolved solids (TDS) 70300 na 10, 12 SMCL-CA 2 500 (1,000) D

Laboratory alkalinity (as CaCO3) 3 29801 na 4, 4.0 na na D

1

 For constituents with two LT-MDLs listed, the first value was in use before 10/01/2010, and the second value was in use after 10/01/2010. The highest 

LT-MDL is used for this report. Total dissolved solids has a method reporting level (MRL), rather than an LT-MDL.

2

 The recommended SMCL-CA benchmarks for chloride, sulfate, and TDS are listed with the upper SMCL-CA benchmarks in parentheses.

3

 Laboratory alkalinity results are presented in table 5.
Tables 51

Table 4G. Radioactive constituents, comparative benchmarks, and reporting information for laboratory analyses.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. 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; MCL-CA, California Department of Public Health 

maximum contaminant level. Other abbreviations: CAS, chemical Abstract Service; ssLC, sample-specific critical level; CSU, combined standard 

uncertainty; pCi/L, picocuries per liter; D, detected in groundwater samples (tables 12, 13, 14, and 16)]

Constituent1

USGS 

parameter

code

CAS number Reporting

level

Reporting 

uncertainty

Benchmark 

type

Bemchmark 

level Detection

Radon-2222 82303 14859-67-7 ssLC CSU Proposed

MCL-US

4,000 D

Gross alpha particle 

activity, 72-hour and 

30-day counts 3

62636, 62639 12587-46-1 ssLC CSU MCL-US 5 15 D

Gross beta particle 

activity, 72-hour and 

30-day counts 3

62642, 62645 14587-47-2 ssLC CSU MCL-US 50 D

Uranium-2343 22610 13966-29-5 ssLC CSU MCL-CA 6 20 D

Uranium-2353 22620 15117-96-1 ssLC CSU MCL-CA 6 20 D

Uranium-2383 22603 7440-61-1 ssLC CSU MCL-CA 6 20 D

Tritium4 07000 10028-17-8 ssLC CSU MCL-CA 20,000 D

1

 All radioactive constituents are reported as activities in units of picocuries per liter (pCi/L).

2

 USGS National Water Quality Laboratory (USGSNWQL).

3

 Eberline Analytical Services (contract laboratory, CA-EBERL).

4

 Tritium was measured by the USGS Stable Isotope and Tritium Laboratory, Menlto Park, California (USGSH3CA) and by the Lawrence Livermore 

National Laboratory (LLNL). Data from LLNL were not available in time for inclusion in this report. 

5

 The MCL-US benchmark for gross alpha particle activity applies to adjusted gross alpha, which is equal to measured gross alpha activity minus uranium 

activity.

6

 The MCL-CA benchmark for uranium applies to the sum of uranium-234, uranium-235, and uranium-238. 

Table 4H. Arsenic and iron species, comparative benchmarks, and reporting information for the U.S. Geological Survey (USGS) Trace 

Metal Laboratory, Boulder, Colorado, analyses.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Benchmark types and benchmark values as of January 10, 

2012. Benchmark type: SMCL-CA, California Department of Public Health secondary maximum contaminant level; MCL-US, U.S. Environmental Protection 

Agency maximum contaminant level; na, not available; μg/L, microgram per liter. Other abbreviations: CAS, Chemical Abstract Service; MDL, method 

detection limit; D, detected in groundwater samples (table 15)]

Constituent 

(valence state)

USGS

parameter

code

CAS number MDL 

(μg/L)

Benchmark 

type1

Benchmark

level

(μg/L)

Detection

Arsenic (total) 99033 7440-38-2 0.15 MCL-US 10 D

Arsenic (III) 99034 22569-72-8 0.5 na na D

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

Iron (II) 01047 7439-89-6 2 na na D

1

 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.
52 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table 4I. Dissolved gases and isotope tracers, comparison benchmarks and reporting information for laboratory analyses.

[The five-digit U.S. Geological Survey (USGS) parameter code is used to uniquely identify a specific constituent or property. Laboratory entity codes in the 

USGS National Water Information System (NWIS) for laboratories other than the USGS National Water Quality Laboratory (NWQL) are given in parentheses 

after the laboratory names. Elements: H, hydrogen; O, oxygen; B, boron; Sr, strontium; C, carbon. Reporting units: cm3 STP/g, cubic centimeters of gas at 

standard temperature and pressure per gram of water; pmc, percent modern carbon. Other abbreviations: CAS, Chemical Abstract Service; na, not available; D, 

detected in groundwater samples (table 16); %, percent]

Constituent

USGS 

parameter 

code

CAS number Method 

uncertainty

Reporting

units

Benchmark 

type

Benchmark

level

(pCi/L)

Detection

Dissolved noble gases 1

Argon 85563 7440-37-1 2% cm3 STP/g na na D5

Helium-4 85561 7440-59-7 2% cm3 STP/g na na D5

Krypton 85565 7439-90-9 2% cm3 STP/g na na D5

Neon 61046 7440-01-09 2% cm3 STP/g na na D5

Xenon 85567 7440-63-3 2% cm3 STP/g na na D5

Isotope tracers

Helium-3 / Helium-4 1 61040 na / 7440-59-7 0.75% atom ratio na na D5

δ2H in water 2 82082 na 2 per mil na na D

δ18O in water 2 82085 na 0.20 per mil na na D

δ11B in water 3 62648 na na per mil na na D5

Strontium isotope ratio (87Sr/86Sr) 3 75978 na 0.000 atom ratio na na D5

δ13C in dissolved inorganic carbon 4 82081 na 0.05 per mil na na D

Carbon-14 4 49933 14762-75-5 0.3 pmc na na D

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

 Constituent was detected, but data were not available in time for inclusion in this report.

Table 4J. Microbial indicators, comparative benchmarks, and reporting information for the IDEXX Colilert® field test kit analyses.

[The five-digit U.S. Geological Survey (USGS) parameter code is used to uniquely identify a specific constituent or property. Method detection limit, benchmark 

type, and benchmark level as of January 10, 2012. 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: MDL, method detection limit; D, detected in groundwater samples (table 17)]

Constituent

USGS 

parameter 

code

Primary source MDL Benchmark 

type

Benchmark

value Detection

Escherichia coli (E. coli) 99596 Sewage and animal 

waste indicator

presence / 

absence

TT-US Zero D

Total coliform (including 

fecal coliform and E. coli)

99595 Sewage and animal 

waste indicator

presence / 

absence

MCL-US 5 percent of samples 

positive per month

D
Tables 53

Table 5. Field water-quality indicators in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Reporting level, benchmark type, and benchmark level as of January 10, 2012. Benchmark type: SMCL-US, U.S. Environmental Protection Agency secondary maximum contaminant level; SMCL-CA, California Department of Public Health secondary maximum contaminant level. Other abbreviations: °C, degrees Celsius; E, estimated or having a higher degree of uncertainty; mg/L, milligrams per liter; nc, not collected; na, not available; RL, reporting limit or range; MRL, minimum reporting level; LT-MDL, long-term method detection level; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium carbonate; *, value greater than benchmark level or outside benchmark range; **, value greater than 

upper benchmark level; –, not detected]

GAMA well 

identification 

number

Dissolved 

oxygen, 

field 

(mg/L) 

(00300) 

Water 

temperature, 

field 

(°C) 

(00010)

pH, field 

(standard 

units) 

(00400)

pH, lab 

(standard 

units) 

(00403)

Specific 

conductance, field 

(μS/cm at 25°C) 

(00095)

Specific 

conductance, lab 

(μS/cm at 25°C) 

(90095)

Alkalinity, 

field 

(mg/L as 

CaCO3) 

(29802)

Bicarbonate, 

field 2

(mg/L) 

(63786)

Carbonate, 

field 2

(mg/L) 

(63788)

Alkalinity, lab 

(mg/L as 

CaCO3) 

(29801)

Bicarbonate2

(mg/L)

Carbonate2

(mg/L)

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

[RL, MRL, or LT-MDL] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [4.0] [1] [0.1] [4.0] [1] [0.1]

CAMP Sacramento Valley Eastside study area (15 grid wells sampled)

CAMP-ES-01 5.6 14.0 * 6.2 6.7 206 211 92.2 112 – 100 122 –

CAMP-ES-02 9.8 16.0 * 6.2 6.8 176 178 nc nc nc 86 105 –

CAMP-ES-03 4.7 19.0 7.2 7.7 223 224 112 136 0.2 120 146 0.3

CAMP-ES-04 1.3 22.0 7.2 7.6 367 367 nc nc nc 178 216 0.4

CAMP-ES-05 9.8 14.0 6.7 7.3 161 168 nc nc nc 89 108 0.1

CAMP-ES-06 10.3 13.5 6.8 7.3 191 198 nc nc nc 106 129 0.1

CAMP-ES-07 6.6 12.5 6.6 7.2 203 206 100 122 – 109 133 0.1

CAMP-ES-08 6.2 13.0 6.6 6.8 192 197 nc nc nc 104 127 –CAMP-ES-09 6.0 21.0 7.5 7.7 274 273 nc nc nc 146 177 0.4

CAMP-ES-10 7.4 17.0 6.7 6.8 214 214 104 126 0.1 113 138 –

CAMP-ES-11 7.4 13.5 6.6 6.9 188 188 92.2 112 – 101 123 –

CAMP-ES-12 5.3 12.5 * 5.8 * 6.2 159 157 nc nc nc 75 92 –

CAMP-ES-13 5.5 14.0 * 6.0 * 6.3 205 210 nc nc nc 95 116 –CAMP-ES-14 6.2 19.5 7.2 7.7 234 230 nc nc nc 121 147 0.3

CAMP-ES-15 6.8 20.0 7.1 7.5 206 207 nc nc nc 102 124 0.2

CAMP Honey Lake Valley study area (15 grid wells sampled)

CAMP-HL-01 6.7 20.5 * 8.8 * 8.8 361 368 nc nc nc 122 140 4.1

CAMP-HL-02 1.0 13.0 7.6 7.9 201 204 72.8 88.3 0.2 82 99 0.4

CAMP-HL-03 0.9 18.0 7.7 7.9 569 584 95.8 116 0.4 98 119 0.4

CAMP-HL-04 4.2 14.0 7.6 7.8 485 483 nc nc nc 158 192 0.6

CAMP-HL-05 8.3 14.5 7.0 7.3 291 296 nc nc nc 112 136 0.1
54 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program GAMA well identification number Dissolved oxygen, field (mg/L) (00300) Water temperature, field (°C) (00010) pH, field (standard units) (00400) pH, lab (standard units) (00403) Specific conductance, field (μS/cm at 25°C) (00095) Specific conductance, lab (μS/cm at 25°C) (90095) Alkalinity, field (mg/L as CaCO3) (29802) Bicarbonate, field 2 (mg/L) (63786) Carbonate, field 2 (mg/L) (63788) Alkalinity, lab (mg/L as CaCO3) (29801) Bicarbo- nate2 (mg/L) Carbonate2 (mg/L) Benchmark type na na SMCL-US SMCL-US SMCL-CA SMCL-CA na na 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 na na [RL, MRL, or LT-MDL] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [4.0] [1] [0.1] [4.0] [1] [0.1] CAMP Honey Lake Valley study area (15 grid wells sampled)—Continued CAMP-HL-06 7.8 14.5 * 6.4 7.3 291 303 nc nc nc 66 80 0.1 CAMP-HL-07 3 0.6 13.0 7.9 8.1 * 1,160 * 1,180 nc nc nc 288 347 2.0 CAMP-HL-08 3 0.4 12.5 * 9.2 * 9.2 * 1,070 * 1,090 nc nc nc 548 581 42.4 CAMP-HL-09 6.4 18.0 7.6 7.8 469 481 152 184 0.2 160 194 0.6 CAMP-HL-10 1.5 17.0 7.0 7.5 725 727 148 181 0.2 191 232 0.3 CAMP-HL-11 <0.2 17.0 7.8 8.0 * 1,110 * 1,160 nc nc nc 336 406 1.9 CAMP-HL-12 4.4 15.0 7.3 7.4 775 817 nc nc nc 174 212 0.2 CAMP-HL-13 7.5 14.0 6.5 7.6 186 192 nc nc nc 97 118 0.2 CAMP-HL-14 0.4 15.0 7.8 7.8 897 896 nc nc nc 249 302 0.9 CAMP-HL-15 1.1 15.5 8.0 8.4 * 1,100 * 1,120 nc nc nc 502 598 6.9 CAMP Cascade Range and Modoc Plateau Low Use Basins study area (15 grid wells sampled) CAMP-LU-01 3 0.2 26.5 8.4 8.5 343 339 nc nc nc 170 201 2.9 CAMP-LU-02 3 <0.2 22.0 7.3 7.6 875 865 nc nc nc 380 462 0.8 CAMP-LU-03 1.5 23.0 8.0 8.2 344 333 138 166 0.7 145 174 1.3 CAMP-LU-04 8.5 13.5 7.8 8.0 296 289 142 171 1.1 131 158 0.7 CAMP-LU-05 1.9 18.0 7.5 7.8 372 359 nc nc nc 157 190 0.6 CAMP-LU-06 3 0.2 22.0 7.9 8.1 367 364 nc nc nc 157 189 1.1 CAMP-LU-07 5.7 11.0 7.0 7.1 256 256 nc nc nc 114 139 0.1 CAMP-LU-08 10.9 5.5 * 6.3 E7.4 58 E58 25.1 30.6 nc 31 38 – CAMP-LU-09 1.6 19.5 8.0 8.2 312 314 127 152 1.1 135 162 1.2 CAMP-LU-10 3 0.2 16.5 7.8 8.0 * 1,120 * 1,120 644 770 8.0 621 751 3.5 Table 5. Field water-quality indicators in samples collected for the Cascade Range and Modoc Plateau (CAMP) Groundwater study unit, July through October 2010, California GAMA Priority Basin Project.—Continued [The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Reporting level, benchmark type, and benchmark level as of January 10, 2012. Benchmark type: SMCL-US, U.S. Environmental Protection Agency secondary maximum contaminant level; SMCL-CA, California Department of Public Health secondary maximum contaminant level. Other abbreviations: °C, degrees Celsius; E, estimated or having a higher degree of uncertainty; mg/L, milligrams per liter; nc, not collected; na, not available; RL, reporting limit or range; MRL, minimum reporting level; LT-MDL, long-term method detection level; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium carbonate; *, value greater than benchmark level or outside benchmark range; **, value greater than upper benchmark level; –, not detected]
Tables 55

GAMA well 

identification 

number

Dissolved 

oxygen, 

field 

(mg/L) 

(00300) 

Water 

temperature, 

field 

(°C) 

(00010)

pH, field 

(standard 

units) 

(00400)

pH, lab 

(standard 

units) 

(00403)

Specific 

conductance, field 

(μS/cm at 25°C) 

(00095)

Specific 

conductance, lab 

(μS/cm at 25°C) 

(90095)

Alkalinity, 

field 

(mg/L as 

CaCO3) 

(29802)

Bicarbonate, 

field 2

(mg/L) 

(63786)

Carbonate, 

field 2

(mg/L) 

(63788)

Alkalinity, lab 

(mg/L as 

CaCO3) 

(29801)

Bicarbonate2

(mg/L)

Carbonate2

(mg/L)

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

[RL, MRL, or LT-MDL] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [4.0] [1] [0.1] [4.0] [1] [0.1]

CAMP Cascade Range and Modoc Plateau Low Use Basins study area (15 grid wells sampled)—Continued

CAMP-LU-11 3 7.0 14.5 7.0 7.4 207 206 nc nc nc 91 111 0.1

CAMP-LU-12 3 8.9 8.5 6.6 7.0 136 138 nc nc nc 71 87 –CAMP-LU-13 1.0 14.0 6.9 7.2 351 353 nc nc nc 161 196 0.1

CAMP-LU-14 7.9 9.0 7.1 7.5 113 115 56.4 68.8 nc 65 79 0.1

CAMP-LU-15 7.2 8.5 7.3 7.7 153 156 75.4 91.9 nc 80 97 0.2

CAMP Quaternary Volcanic Areas study area (15 grid wells sampled)

CAMP-QV-01 12.0 3.5 * 5.7 E7.4 41 E40 nc nc nc 22 27 –

CAMP-QV-02 11.0 5.0 * 6.3 E7.2 44 E44 18.5 22.6 – 24 29 –

CAMP-QV-03 3 0.8 25.5 7.3 7.7 306 303 nc nc nc 133 161 0.4

CAMP-QV-04 3 1.0 14.5 7.9 8.1 872 887 nc nc nc 361 435 2.5CAMP-QV-05 10.4 10.0 7.5 7.8 117 125 nc nc nc 63 76 0.2

CAMP-QV-06 3.0 27.0 8.5 8.5 161 160 nc nc nc 78 92 1.3

CAMP-QV-07 9.8 8.0 7.6 8.0 102 108 nc nc nc 56 68 0.3

CAMP-QV-08 7.3 11.0 7.4 7.8 155 162 nc nc nc 81 98 0.3CAMP-QV-09 10.0 9.0 7.2 7.7 146 150 nc nc nc 78 95 0.2

CAMP-QV-10 3 7.4 14.0 6.8 7.4 240 247 nc nc nc 135 164 0.2

CAMP-QV-11 6.3 10.5 * 6.4 7.1 203 208 nc nc nc 111 135 0.1

CAMP-QV-12 4.6 12.0 * 6.3 7.1 173 178 nc nc nc 94 115 0.1

CAMP-QV-13 8.7 12.0 6.7 7.5 187 189 nc nc nc 98 119 0.2

CAMP-QV-14 3.6 14.5 8.5 * E8.6 81 E86 nc nc nc 45 53 1.0CAMP-QV-15 9.8 9.0 6.5 7.5 151 155 nc nc nc 79 96 0.1

Table 5. Field water-quality indicators in samples collected for the Cascade Range and Modoc Plateau (CAMP) Groundwater study unit, July through October 2010, California 

GAMA Priority Basin Project.—Continued

[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Reporting level, benchmark type, and benchmark level as of January 10, 2012. Benchmark type: SMCL-US, U.S. Environmental Protection Agency secondary maximum contaminant level; SMCL-CA, California Department of Public Health secondary maximum contaminant level. Other abbreviations: °C, degrees Celsius; E, estimated or having a higher degree of uncertainty; mg/L, milligrams per liter; nc, not collected; na, not available; RL, reporting limit or range; MRL, minimum reporting level; LT-MDL, long-term method detection level; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium carbonate; *, value greater than benchmark level or outside benchmark range; **, value greater than 

upper benchmark level; –, not detected]
56 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program Table 5. Field water-quality indicators in samples collected for the Cascade Range and Modoc Plateau (CAMP) Groundwater study unit, July through October 2010, California GAMA Priority Basin Project.—Continued [The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Reporting level, benchmark type, and benchmark level as of January 10, 2012. Benchmark type: SMCL-US, U.S. Environmental Protection Agency secondary maximum contaminant level; SMCL-CA, California Department of Public Health secondary maximum contaminant level. Other abbreviations: °C, degrees Celsius; E, estimated or having a higher degree of uncertainty; mg/L, milligrams per liter; nc, not collected; na, not available; RL, reporting limit or range; MRL, minimum reporting level; LT-MDL, long-term method detection level; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium carbonate; *, value greater than benchmark level or outside benchmark range; **, value greater than upper benchmark level; –, not detected] GAMA well identification number Dissolved oxygen, field (mg/L) (00300) Water temperature, field (°C) (00010) pH, field (standard units) (00400) pH, lab (standard units) (00403) Specific conductance, field (μS/cm at 25°C) (00095) Specific conductance, lab (μS/cm at 25°C) (90095) Alkalinity, field (mg/L as CaCO3) (29802) Bicarbonate, field 2 (mg/L) (63786) Carbonate, field 2 (mg/L) (63788) Alkalinity, lab (mg/L as CaCO3) (29801) Bicarbo- nate2 (mg/L) Carbonate2 (mg/L) Benchmark type na na SMCL-US SMCL-US SMCL-CA SMCL-CA na na 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 na na [RL, MRL, or LT-MDL] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [4.0] [1] [0.1] [4.0] [1] [0.1] CAMP Shasta Valley and Mount Shasta Volcanic Area study area (15 grid wells sampled) CAMP-SH-01 5.0 15.0 6.8 7.2 437 435 nc nc nc 226 275 0.2 CAMP-SH-02 4.7 16.0 6.6 7.0 538 536 224 273 0.1 237 289 0.1 CAMP-SH-03 4.7 13.5 7.3 7.7 520 521 248 300 1.0 255 310 0.7 CAMP-SH-04 4.4 11.5 7.2 7.5 166 169 nc nc nc 74 90 0.1 CAMP-SH-05 10.6 7.5 * 6.4 7.1 101 105 nc nc nc 54 66 – CAMP-SH-06 9.3 9.0 6.5 7.0 99 102 nc nc nc 53 65 – CAMP-SH-07 10.8 6.5 * 6.3 E6.8 50 E52 nc nc nc 28 34 – CAMP-SH-08 4.0 13.0 6.7 7.1 259 263 nc nc nc 120 146 0.1 CAMP-SH-09 5.8 15.5 6.9 7.2 503 513 nc nc nc 222 270 0.2 CAMP-SH-10 3.2 13.0 6.8 7.2 341 340 nc nc nc 165 201 0.1 CAMP-SH-11 0.3 14.0 7.2 7.3 303 303 nc nc nc 150 183 0.2 CAMP-SH-12 7.2 14.0 7.1 7.2 867 868 nc nc nc 384 468 0.3 CAMP-SH-13 9.3 11.5 6.6 7.0 267 270 nc nc nc 122 149 0.1 CAMP-SH-14 10.5 8.0 * 6.3 7.5 119 120 60.5 73.7 – 66 80 0.1 CAMP-SH-15 0.2 16.5 7.3 7.7 * 1,120 * 1,130 nc nc nc 399 484 1.1 CAMP Tertiary Volcanic Areas study area (15 grid wells sampled) CAMP-TV-01 0.8 19.0 7.9 8.0 ** 2,300 ** 2,390 nc nc nc 104 126 0.6 CAMP-TV-02 8.2 16.0 7.2 7.5 158 156 nc nc nc 78 95 0.1 CAMP-TV-03 4 11.2 14.0 6.9 7.1 184 185 nc nc nc 96 117 0.1 CAMP-TV-04 7.4 13.5 7.6 8.0 133 140 61.1 74.4 – 67 81 0.4 CAMP-TV-05 6.9 17.5 7.5 7.8 203 209 97.0 118 – 106 129 0.4
Tables 57

Table 5. Field water-quality indicators in samples collected for the Cascade Range and Modoc Plateau (CAMP) Groundwater study unit, July through October 2010, California 

GAMA Priority Basin Project.—Continued

[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Reporting level, benchmark type, and benchmark level as of January 10, 2012. Benchmark type: SMCL-US, U.S. Environmental Protection Agency secondary maximum contaminant level; SMCL-CA, California Department of Public Health secondary maximum contaminant level. Other abbreviations: °C, degrees Celsius; E, estimated or having a higher degree of uncertainty; mg/L, milligrams per liter; nc, not collected; na, not available; RL, reporting limit or range; MRL, minimum reporting level; LT-MDL, long-term method detection level; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium carbonate; *, value greater than benchmark level or outside benchmark range; **, value greater than 

upper benchmark level; –, not detected]

GAMA well 

identification 

number

Dissolved 

oxygen, 

field 

(mg/L) 

(00300) 

Water 

temperature, 

field 

(°C) 

(00010)

pH, field 

(standard 

units) 

(00400)

pH, lab 

(standard 

units) 

(00403)

Specific 

conductance, field 

(μS/cm at 25°C) 

(00095)

Specific 

conductance, lab 

(μS/cm at 25°C) 

(90095)

Alkalinity, 

field 

(mg/L as 

CaCO3) 

(29802)

Bicarbonate, 

field 2

(mg/L) 

(63786)

Carbonate, 

field 2

(mg/L) 

(63788)

Alkalinity, lab 

(mg/L as 

CaCO3) 

(29801)

Bicarbonate2

(mg/L)

Carbonate2

(mg/L)

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

[RL, MRL, or LT-MDL] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [4.0] [1] [0.1] [4.0] [1] [0.1]

CAMP Tertiary Volcanic Areas study area (15 grid wells sampled)—Continued

CAMP-TV-06 9.4 9.5 8.0 7.7 118 121 nc nc nc 64 78 0.2

CAMP-TV-07 7.5 8.5 7.8 8.1 170 176 nc nc nc 95 114 0.7

CAMP-TV-08 5.9 17.0 8.3 8.1 162 162 nc nc nc 82 99 0.6

CAMP-TV-09 4.9 10.5 7.5 8.4 301 311 nc nc nc 166 198 2.3CAMP-TV-10 8.1 8.0 * 6.2 7.5 106 116 nc nc nc 62 75 0.1CAMP-TV-11 7.9 8.0 7.0 7.7 118 122 56.6 68.9 0.1 63 76 0.2

CAMP-TV-12 8.6 7.5 6.8 7.6 128 133 nc nc nc 71 86 0.2

CAMP-TV-13 8.6 8.5 6.6 6.7 151 157 75.2 91.7 – 85 104 –

CAMP-TV-14 7.8 10.0 * 5.8 E7.2 62 E64 26.3 32.1 – 31 38 –

CAMP-TV-15 4.9 19.0 * 9.3 * 9.2 280 287 nc nc nc 119 126 9.2

1 The SMCL-CA for specific conductance has recommended and upper benchmark levels. The upper benchmark level is shown in parentheses.2 Bicarbonate and carbonate concentrations were calculated from alkalinity and pH values using the advanced speciation method (http://or.water.usgs.gov/alk/methods.html) with pK1 = 6.35, pK2 = 10.33, and 

pKW = 14. Field values used field measurements, and lab values used laboratory measurements.

3 Hydrogen sulfide smell noted during sampling.4 Conveyance from the TV-03 spring source to the point of use is an open channel.
58 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program Table 6.

Volatile organic compounds (VOCs) detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California 

GAMA Priority Basin Project.[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from 90 grid wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency within each class of primary use or source. All analytes are listed in table 4A. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type, and benchmark level as of January 10, 2012. 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; MCL-CA, California Department of Public Health maximum contaminant level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to the CAMP SRL; NWIS, USGS National Water Information System]

Primary use 

or source

Disinfection 

byproduct Solvent Gasoline oxygenate Natural Fumigant Refrigerant Summaries by study unit, well, and study area

GAMA 

identification 

number

Chloroform 

(μg/L) 

(32106)

Perchloroethene 

(PCE) 

(μg/L) 

(34475)

Dichloromethane 

(μg/L) 

(34423)

1,1-Dichloroethene 

(1,1-DCE) 

(μg/L) 

(34501)

1,1,1-Trichloroethane

(1,1,1-TCA) 

(μg/L) 

(34506)

Methyl tertbutyl ether 

(MTBE) 

(μg/L) 

(78032)

Carbon 

disulfide 

(μg/L) 

(77041)

1,4-Dichlorobenzene 

(μg/L) 

(34571)

1,1,2-Trichloro1,2,2-

trifluoroethane 

(CFC-113) (μg/L) 

(77652)

Detections 

per 

well

VOC 

detection 

summary 1

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

Benchmark level 2 80 5 5 6 200 13 160 5 1,200

[LRL] or [SRL] [0.03] [0.03] [0.04] [0.02] [0.03] [0.1] 3 [0.04] [0.03] [0.03]

CAMP grid wells (90 wells sampled)

Number of wells with detections 14 7 2 2 1 6 3 1 1 27

Detection frequency (percent) 15.6 7.8 2.2 2.2 1.1 6.7 3.3 1.1 1.1 30

Total detections 46

CAMP Sacramento Valley Eastside study area (15 grid wells sampled)

CAMP-ES-01 0.04 0.04 – – – – – – – 2CAMP-ES-02 0.71 0.08 – – – – – – – 2CAMP-ES-04 4 0.05 – E0.02 – – – – – – 2

CAMP-ES-05 0.06 – – – – – – – – 1

CAMP-ES-11 4 0.03 – – – – – – – – 1

CAMP-ES-12 E0.01 – – – – – – – 0.31 2

CAMP-ES-13 4 0.10 0.11 – – – 0.09 – – – 3

CAMP-ES-15 – – – – – – – – – 8Number of wells with detections 7 3 1 0 0 1 0 0 1 8

Detection frequency (percent) 46.7 20.0 6.7 0 0 6.7 0 0 6.7 53

Total detections 21
Tables 59

Table 6. Volatile organic compounds (VOCs) detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from 90 grid wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency within each class of primary use or source. All analytes are listed in table 4A. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type, and benchmark level as of January 10, 2012. 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; MCL-CA, California Department of Public Health maximum contaminant level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to the CAMP SRL; NWIS, USGS National Water Information System]

Primary use 

or source

Disinfection 

byproduct Solvent Gasoline oxygenate Natural Fumigant Refrigerant Summaries by study unit, well, and study area

GAMA 

identification 

number

Chloroform 

(μg/L) 

(32106)

Perchloroethene 

(PCE) 

(μg/L) 

(34475)

Dichloromethane 

(μg/L) 

(34423)

1,1-Dichloroethene 

(1,1-DCE) 

(μg/L) 

(34501)

1,1,1-Trichloroethane

(1,1,1-TCA) 

(μg/L) 

(34506)

Methyl tertbutyl ether 

(MTBE) 

(μg/L) 

(78032)

Carbon 

disulfide 

(μg/L) 

(77041)

1,4-Dichlorobenzene 

(μg/L) 

(34571)

1,1,2-Trichloro1,2,2-

trifluoroethane 

(CFC-113) (μg/L) 

(77652)

Detections 

per 

well

VOC 

detection 

summary 1

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

Benchmark level 2 80 5 5 6 200 13 160 5 1,200

[LRL] or [SRL] [0.03] [0.03] [0.04] [0.02] [0.03] [0.1] 3 [0.04] [0.03] [0.03]

CAMP Honey Lake Valley study area (15 grid wells sampled)

CAMP-HL-02 – – – E0.02 – – – – – 1

CAMP-HL-03 – – – E0.01 – 0.69 – – – 2CAMP-HL-05 – E0.02 – – – – – – – 1CAMP-HL-08 – – – – – – 0.11 – – 1CAMP-HL-10 0.03 – – – – – – – – 1CAMP-HL-12 E0.02 – – – – – – – – 1CAMP-HL-15 – 0.10 – – – – – – – 1Number of wells with detections 2 2 0 2 0 1 1 0 0 7

Detection frequency (percent) 13.3 13.3 0 13.3 0 6.7 6.7 0 0 47

Total detections 8

CAMP Cascade Range and Modoc Plateau Low Use Basins study area (15 grid wells sampled)

CAMP-LU-02 – – – – – – E0.31 – – 2

CAMP-LU-13 4 0.06 – – – – – – – – 1

Number of wells with detections 1 0 0 0 0 0 1 0 0 2

Detection frequency (percent) 6.7 0 0 0 0 0 6.7 0 0 13

Total detections 3
60 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program Table 6.

Volatile organic compounds (VOCs) detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California 

GAMA Priority Basin Project.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from 90 grid wells were analyzed, but only samples with detections are 

listed. Analytes are listed in order of decreasing detection frequency within each class of primary use or source. All analytes are listed in table 4A. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type, and benchmark level as of January 10, 2012. 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; MCL-CA, California Department of Public Health maximum contaminant level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to the CAMP SRL; NWIS, USGS National Water Information System]

Primary use 

or source

Disinfection 

byproduct Solvent Gasoline oxygenate Natural Fumigant Refrigerant Summaries by study unit, well, and study area

GAMA 

identification 

number

Chloroform 

(μg/L) 

(32106)

Perchloroethene 

(PCE) 

(μg/L) 

(34475)

Dichloromethane 

(μg/L) 

(34423)

1,1-Dichloroethene 

(1,1-DCE) 

(μg/L) 

(34501)

1,1,1-Trichloroethane

(1,1,1-TCA) 

(μg/L) 

(34506)

Methyl tertbutyl ether 

(MTBE) 

(μg/L) 

(78032)

Carbon 

disulfide 

(μg/L) 

(77041)

1,4-Dichlorobenzene 

(μg/L) 

(34571)

1,1,2-Trichloro1,2,2-

trifluoroethane 

(CFC-113) (μg/L) 

(77652)

Detections 

per 

well

VOC 

detection 

summary 1

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

Benchmark level 2 80 5 5 6 200 13 160 5 1,200

[LRL] or [SRL] [0.03] [0.03] [0.04] [0.02] [0.03] [0.1] 3 [0.04] [0.03] [0.03]

CAMP Quaternary Volcanic Areas study area (15 grid wells sampled)

CAMP-QV-04 – – – – – – 0.05 – – 1

CAMP-QV-09 – E0.02 – – – – – – – 1CAMP-QV-11 – – – – – E0.10 – – – 1Number of wells with detections 0 1 0 0 0 1 1 0 0 3

Detection frequency (percent) 0 6.7 0 0 0 6.7 6.7 0 0 20

Total detections 3

CAMP Shasta Valley and Mount Shasta Volcanic Area study area (15 grid wells sampled)

CAMP-SH-02 4 0.05 – – – – – – – – 1

CAMP-SH-06 – – – – – E0.02 – – – 1

CAMP-SH-09 4 E0.01 – – – – – – – – 1

CAMP-SH-15 – – – – – 0.61 – – – 1Number of wells with detections 2 0 0 0 0 2 0 0 0 4

Detection frequency (percent) 13.3 0 0 0 0 13.3 0 0 0 27

Total detections 4

CAMP Tertiary Volcanic Areas study area (15 grid wells sampled)

CAMP-TV-10 4 0.10 E0.01 – – 0.05 – – – – 3

CAMP-TV-12 – – – – – 0.51 – E0.01 – 2CAMP-TV-15 0.81 – 0.12 – – – – – – 2Number of wells with detections 2 1 1 0 1 1 0 1 0 3

Detection frequency (percent) 13.3 6.7 0 0 0 6.7 0 0 0 20

Total detections 7
Tables 61

Primary use or source Gasoline hydrocarbon

Summaries by study 

unit, well, and study 

area

GAMA 

identification 

number

Benzene 

(μg/L) 

(34030)

2-Ethyltoluene 

(μg/L) 

(77220)

Isopropylbenzene 

(μg/L) 

(77223)

4-Isopropyltoluene 

(μg/L) 

(77356)

n-Propylbenzene 

(μg/L) 

(77224)

1,2,3,4-Tetramethylbenzene 

(μg/L) 

(49999)

1,2,3,5-Tetramethylbenzene 

(μg/L) 

(50000)

1,2,3-Trimethylbenzene 

(μg/L) 

(77221)

1,3,5-Trimethylbenzene 

(μg/L) 

(77226)

Detections 

per 

well

VOC 

detection 

summary 1

Benchmark type MCL-CA na NL-CA na NL-CA na na na NL-CABenchmark level 1 na 770 na 260 na na na 330[LRL] or [SRL] [0.03] [0.03] [0.04] [0.06] [0.04] [0.1] [0.1] [0.1] [0.03]CAMP grid wells (90 wells sampled)Number of wells with detections 1 1 1 1 1 1 1 1 1 27

Detection frequency (percent) 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 1.1 30

Total detections 46

CAMP Sacramento Valley Eastside study area (15 grid wells sampled)

CAMP-ES-01 – – – – – – – – – 2

CAMP-ES-02 – – – – – – – – – 2

CAMP-ES-04 – – – – – – – – – 2

CAMP-ES-05 – – – – – – – – – 1

CAMP-ES-11 – – – – – – – – – 1

CAMP-ES-12 – – – – – – – – – 2

CAMP-ES-13 – – – – – – – – – 3

CAMP-ES-15 – 0.11 0.02 0.02 0.03 0.2 0.1 0.2 0.1 8

Number of wells with detections 0 1 1 1 1 1 1 1 1 8

Detection frequency (percent) 0 6.7 6.7 6.7 6.7 6.7 6.7 6.7 6.7 53

Total detections 21

Table 6. Volatile organic compounds (VOCs) detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from 90 grid wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency within each class of primary use or source. All analytes are listed in table 4A. GAMA well identification number: ES, Sacramento Valley 

Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type, and benchmark level as of January 10, 2012. 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; MCL-CA, California Department of Public Health maximum contaminant level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to the CAMP SRL; NWIS, USGS National Water Information System]
62 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program Table 6.

Volatile organic compounds (VOCs) detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California 

GAMA Priority Basin Project.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from 90 grid wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency within each class of primary use or source. All analytes are listed in table 4A. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type, and benchmark level as of January 10, 2012. 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; MCL-CA, California Department of Public Health maximum contaminant level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to the CAMP SRL; NWIS, USGS National Water Information System]

Primary use or source Gasoline hydrocarbon

Summaries by study 

unit, well, and study 

area

GAMA 

identification 

number

Benzene 

(μg/L) 

(34030)

2-Ethyltoluene 

(μg/L) 

(77220)

Isopropylbenzene 

(μg/L) 

(77223)

4-Isopropyltoluene 

(μg/L) 

(77356)

n-Propylbenzene 

(μg/L) 

(77224)

1,2,3,4-Tetramethylbenzene 

(μg/L) 

(49999)

1,2,3,5-Tetramethylbenzene 

(μg/L) 

(50000)

1,2,3-Trimethylbenzene 

(μg/L) 

(77221)

1,3,5-Trimethylbenzene 

(μg/L) 

(77226)

Detections 

per 

well

VOC 

detection 

summary 1

Benchmark type MCL-CA na NL-CA na NL-CA na na na NL-CABenchmark level 1 na 770 na 260 na na na 330[LRL] or [SRL] [0.03] [0.03] [0.04] [0.06] [0.04] [0.1] [0.1] [0.1] [0.03]

CAMP Honey Lake Valley study area (15 grid wells sampled)

CAMP-HL-02 – – – – – – – – – 1

CAMP-HL-03 – – – – – – – – – 2

CAMP-HL-05 – – – – – – – – – 1

CAMP-HL-08 – – – – – – – – – 1

CAMP-HL-10 – – – – – – – – – 1

CAMP-HL-12 – – – – – – – – – 1

CAMP-HL-15 – – – – – – – – – 1

Number of wells with detections 0 0 0 0 0 0 0 0 0 7

Detection frequency (percent) 0 0 0 0 0 0 0 0 0 47

Total detections 8

CAMP Cascade Range and Modoc Plateau Low Use Basins study area (15 grid wells sampled)

CAMP-LU-02 E0.01 – – – – – – – – 2

CAMP-LU-13 – – – – – – – – – 1

Number of wells with detections 1 0 0 0 0 0 0 0 0 2

Detection frequency (percent) 6.7 0 0 0 0 0 0 0 0 13

Total detections 3
Tables 63

Table 6. Volatile organic compounds (VOCs) detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from 90 grid wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency within each class of primary use or source. All analytes are listed in table 4A. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type, and benchmark level as of January 10, 2012. 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; MCL-CA, California Department of Public Health maximum contaminant level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to the CAMP SRL; NWIS, USGS National Water Information System]

Primary use or source Gasoline hydrocarbon

Summaries by study 

unit, well, and study 

area

GAMA 

identification 

number

Benzene 

(μg/L) 

(34030)

2-Ethyltoluene 

(μg/L) 

(77220)

Isopropylbenzene 

(μg/L) 

(77223)

4-Isopropyltoluene 

(μg/L) 

(77356)

n-Propylbenzene 

(μg/L) 

(77224)

1,2,3,4-Tetramethylbenzene 

(μg/L) 

(49999)

1,2,3,5-Tetramethylbenzene 

(μg/L) 

(50000)

1,2,3-Trimethylbenzene 

(μg/L) 

(77221)

1,3,5-Trimethylbenzene 

(μg/L) 

(77226)

Detections 

per 

well

VOC 

detection 

summary 1

Benchmark type MCL-CA na NL-CA na NL-CA na na na NL-CABenchmark level 1 na 770 na 260 na na na 330[LRL] or [SRL] [0.03] [0.03] [0.04] [0.06] [0.04] [0.1] [0.1] [0.1] [0.03]

CAMP Quaternary Volcanic Areas study area (15 grid wells sampled)

CAMP-QV-04 – – – – – – – – – 1

CAMP-QV-09 – – – – – – – – – 1

CAMP-QV-11 – – – – – – – – – 1

Number of wells with detections 0 0 0 0 0 0 0 0 0 3

Detection frequency (percent) 0 0 0 0 0 0 0 0 0 20

Total detections 3

CAMP Shasta Valley and Mount Shasta Volcanic Area study area (15 grid wells sampled)

CAMP-SH-02 – – – – – – – – – 1

CAMP-SH-06 – – – – – – – – – 1

CAMP-SH-09 – – – – – – – – – 1

CAMP-SH-15 – – – – – – – – – 1

Number of wells with detections 0 0 0 0 0 0 0 0 0 4

Detection frequency (percent) 0 0 0 0 0 0 0 0 0 27

Total detections 4
64 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program Table 6.

Volatile organic compounds (VOCs) detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California 

GAMA Priority Basin Project.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from 90 grid wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency within each class of primary use or source. All analytes are listed in table 4A. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type, and benchmark level as of January 10, 2012. 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; MCL-CA, California Department of Public Health maximum contaminant level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to the CAMP SRL; NWIS, USGS National Water Information System]

Primary use or source Gasoline hydrocarbon

Summaries by study 

unit, well, and study 

area

GAMA 

identification 

number

Benzene 

(μg/L) 

(34030)

2-Ethyltoluene 

(μg/L) 

(77220)

Isopropylbenzene 

(μg/L) 

(77223)

4-Isopropyltoluene 

(μg/L) 

(77356)

n-Propylbenzene 

(μg/L) 

(77224)

1,2,3,4-Tetramethylbenzene 

(μg/L) 

(49999)

1,2,3,5-Tetramethylbenzene 

(μg/L) 

(50000)

1,2,3-Trimethylbenzene 

(μg/L) 

(77221)

1,3,5-Trimethylbenzene 

(μg/L) 

(77226)

Detections 

per 

well

VOC 

detection 

summary 1

Benchmark type MCL-CA na NL-CA na NL-CA na na na NL-CABenchmark level 1 na 770 na 260 na na na 330[LRL] or [SRL] [0.03] [0.03] [0.04] [0.06] [0.04] [0.1] [0.1] [0.1] [0.03]

CAMP Tertiary Volcanic Areas study area (15 grid wells sampled)

CAMP-TV-10 – – – – – – – – – 3

CAMP-TV-12 – – – – – – – – – 2

CAMP-TV-15 – – – – – – – – – 2

Number of wells with detections 0 0 0 0 0 0 0 0 0 3

Detection frequency (percent) 0 0 0 0 0 0 0 0 0 20

Total detections 7

1 Study reporting levels (SRLs) for acetone (no detections are reported), tetrahydrofuran (no detections are reported), toluene (detections with concentrations <0.69 μg/L are reported as non-detections), 

and 1,2,4-trimethylbenzene (detections with concentrations <0.56 μg/L are reported as non-detections) are from Fram and others (2012). All detections of these four constituents in samples from the CAMP study unit had concentrations less than the SRLs: acetone (QV-10, 0.6 μg/L), tetrahydrofuran (TV-15, 3 μg/L), toluene (HL-01, E0.02 μg/L and TV-15, 0.03 μg/L), and 1,2,4-trimethylbenzene (55 samples at concentrations ranging from E0.02 μg/L to 0.5 μg/L; median = 0.06 μg/L). 

2 The MCL-US benchmark level for trihalomethanes is for the sum of chloroform, bromoform, bromodichloromethane, and dibromochloromethane.3 All detections of carbon disulfide had concentrations greater than the SRL of 0.04 μg/L defined by Fram and others (2012).4 Wells treated with chlorine that have chloroform detections: downhole chlorination in LU-13 and TV-10; wellhead chlorination downstream from sampling point in ES-04, ES-11, SH-02, and SH-09; 

downhole bleach treated: ES-13.
Tables 65

Table 7. Pesticides and pesticide degradates detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 90 grid wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency. All analytes are listed in table 4B. GAMA well identification number: HL, Honey Lake Valley study area grid 

well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Laboratory reporting level, benchmark type, and benchmark level as of January 10, 2012. 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. Other abbreviations: 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 or herbicide degradate Insecticide Fungicide Summaries by study unit, well, and study area

GAMA well 

identification number

Deethylatrazine 

(μg/L) 

(04040)

Atrazine 

(μg/L) 

(39632)

Hexazinone 

(μg/L) 

(04025)

Simazine 

(μg/L) 

(04035)

3,4-Dichloroaniline 

(μg/L) 

(61625)

Prometon 

(μg/L) 

(04037)

Tebuthiuron 

(μg/L) 

(82670)

Carbaryl 

(μg/L) 

(82680)

Metalaxyl 

(μg/L) 

(61596)

Detections 

per well

Pesticide detection 

summary

Benchmark type na MCL-CA HAL-US MCL-US na HAL-US HAL-US RSD5-US na

Benchmark level na 1 400 4 na 400 500 400 na

[LRL] [0.014] [0.008] [0.008] [0.006] [0.0042] [0.012] [0.028] [0.06] [0.014]

CAMP study unit (90 grid wells sampled)

Number of wells with detections 23 14 8 8 3 2 1 1 1 28

Detection frequency (percent) 25.6 15.6 8.9 8.9 3.3 2.2 1.1 1.1 1.1 31

Total detections 61

CAMP Honey Lake Valley study area (15 grid wells sampled)

CAMP-HL-05 E0.016 E0.005 – – – – – – – 2

CAMP-HL-11 E0.011 – – – – – – – – 1

CAMP-HL-12 E0.087 0.029 – 0.009 E0.002 – – – – 4

CAMP-HL-15 E0.019 – – – – – – – – 1

Number of wells with detections 4 2 0 1 1 0 0 0 0 4

Detection frequency (percent) 26.7 13.3 0 6.7 6.7 0 0 0 0 27

Total detections 8

CAMP Cascade Range and Modoc Plateau Low Use Basins study area (15 grid wells sampled)

CAMP-LU-04 E0.015 – – – – – – – – 1

CAMP-LU-07 E0.011 – – – – – – – – 1

CAMP-LU-12 – – 0.022 – – – – – – 1

CAMP-LU-15 E0.064 0.019 – – E0.002 – – – – 3

Number of wells with detections 3 1 1 0 1 0 0 0 0 4

Detection frequency (percent) 20.0 6.7 6.7 0 6.7 0 0 0 0 27

Total detections 6
66 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program Table 7. Pesticides and pesticide degradates detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued [The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 90 grid wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency. All analytes are listed in table 4B. GAMA well identification number: HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Laboratory reporting level, benchmark type, and benchmark level as of January 10, 2012. 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. Other abbreviations: 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 or herbicide degradate Insecticide Fungicide Summaries by study unit, well, and study area GAMA well identification number Deethylatrazine (μg/L) (04040) Atrazine (μg/L) (39632) Hexazinone (μg/L) (04025) Simazine (μg/L) (04035) 3,4-Dichloro- aniline (μg/L) (61625) Prometon (μg/L) (04037) Tebuthiuron (μg/L) (82670) Carbaryl (μg/L) (82680) Metalaxyl (μg/L) (61596) Detections per well Pesticide detection summary Benchmark type na MCL-CA HAL-US MCL-US na HAL-US HAL-US RSD5-US na Benchmark level na 1 400 4 na 400 500 400 na [LRL] [0.014] [0.008] [0.008] [0.006] [0.0042] [0.012] [0.028] [0.06] [0.014] CAMP Quaternary Volcanic Areas study area (15 grid wells sampled) CAMP-QV-02 – – 0.071 – – – – – – 1 CAMP-QV-09 E0.006 0.009 – – – – – – – 2 CAMP-QV-15 – – E0.024 – – – – – – 1 Number of wells with detections 1 1 2 0 0 0 0 0 0 3 Detection frequency (percent) 6.7 6.7 13.3 0 0 0 0 0 0 20 Total detections 4 CAMP Shasta Valley and Mount Shasta Volcanic Area study area (15 grid wells sampled) CAMP-SH-01 E0.031 0.013 – E0.006 – – – – – 3 CAMP-SH-02 E0.194 0.010 – 0.011 – – – – – 3 CAMP-SH-03 E0.010 E0.006 – E0.005 – – – – – 3 CAMP-SH-04 E0.004 – 0.009 – – – – – – 2 CAMP-SH-05 E0.012 E0.008 0.014 – – – 1 E0.010 E0.007 E0.009 6 CAMP-SH-06 E0.004 E0.006 – – – – – – – 2 CAMP-SH-08 E0.008 – – – – – – – – 1 CAMP-SH-09 E0.069 0.008 – 0.020 – 0.01 – – – 4 CAMP-SH-10 E0.011 E0.005 – E0.006 – – – – – 3 CAMP-SH-11 E0.007 – – – – – – – – 1 CAMP-SH-12 E0.110 0.022 0.016 0.028 E0.007 0.01 – – – 6 CAMP-SH-13 E0.012 – – 0.012 – – – – – 2 CAMP-SH-15 E0.012 – – – – – – – – 1 Number of wells with detections 13 8 3 7 1 2 1 1 1 13 Detection frequency (percent) 86.7 53.3 20.0 46.7 0 13.3 6.7 6.7 6.7 87 Total detections 37
Tables 67

Table 7. Pesticides and pesticide degradates detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 90 grid wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency. All analytes are listed in table 4B. GAMA well identification number: HL, Honey Lake Valley study area grid 

well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Laboratory reporting level, benchmark type, and benchmark level as of January 10, 2012. 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. Other abbreviations: 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 or herbicide degradate Insecticide Fungicide Summaries by study unit, well, and study area

GAMA well 

identification number

Deethylatrazine 

(μg/L) 

(04040)

Atrazine 

(μg/L) 

(39632)

Hexazinone 

(μg/L) 

(04025)

Simazine 

(μg/L) 

(04035)

3,4-Dichloroaniline 

(μg/L) 

(61625)

Prometon 

(μg/L) 

(04037)

Tebuthiuron 

(μg/L) 

(82670)

Carbaryl 

(μg/L) 

(82680)

Metalaxyl 

(μg/L) 

(61596)

Detections 

per well

Pesticide detection 

summary

Benchmark type na MCL-CA HAL-US MCL-US na HAL-US HAL-US RSD5-US na

Benchmark level na 1 400 4 na 400 500 400 na

[LRL] [0.014] [0.008] [0.008] [0.006] [0.0042] [0.012] [0.028] [0.06] [0.014]

CAMP Tertiary Volcanic Areas study area (15 grid wells sampled)

CAMP-TV-01 E0.007 E0.005 – – – – – – – 2

CAMP-TV-03 2 E0.005 0.009 – – – – – – – 2

CAMP-TV-11 – – 0.062 – – – – – – 1

CAMP-TV-14 – – E0.298 – – – – – – 1

Number of wells with detections 2 2 2 0 0 0 0 0 0 4

Detection frequency (percent) 13.3 13.3 13.3 0 0 0 0 0 0 27

Total detections 6

1 The median matrix-spike recovery is 143 percent for tebuthiuron which is greater than the high end of the acceptable range, 130 percent. High matrix spike recoveries may indicate that reported values 

could be greater than what is in the groundwater sample.

2 Conveyance from the TV-03 spring source to the point of use is an open channel.
68 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table 8. Results for analyses of perchlorate in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July 

through October 2010, California GAMA Priority Basin Project.

[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. 

Information about the analyte given in table 4C. Samples from 84 wells were analyzed for perchlorate (samples were not collected at wells CAMP-ES-01, 

-ES-02, -ES-03, -ES-04, -QV-14, and -TV-12). GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake 

Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; 

SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Minimum reporting level, benchmark 

type, and benchmark level as of January 10, 2012. 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. Other abbreviations: MRL, minimum reporting level; μg/L, micrograms per liter; –, not detected]

GAMA well 

identification 

number

Perchlorate 

(μg/L) 

(63790)

Benchmark type MCL-CA

Benchmark level 6

[MRL] [0.10]

CAMP study unit (84 grid wells sampled)

Number of wells with detections 40

Detection frequency (percent) 48

CAMP Sacramento Valley Eastside study area 

(11 grid wells sampled)

CAMP-ES-05 0.11

CAMP-ES-06 –

CAMP-ES-07 0.11

CAMP-ES-08 0.13

CAMP-ES-09 0.18

CAMP-ES-10 0.14

CAMP-ES-11 0.11

CAMP-ES-12 0.29

CAMP-ES-13 0.27

CAMP-ES-14 0.16

CAMP-ES-15 0.27

Number of wells with detections 10

Detection frequency (percent) 91

CAMP Honey Lake Valley study area (15 grid wells sampled)

CAMP-HL-01 0.36

CAMP-HL-02 –

CAMP-HL-03 0.19

CAMP-HL-04 0.26

CAMP-HL-05 0.16

CAMP-HL-06 0.41

CAMP-HL-07 –

CAMP-HL-08 –

CAMP-HL-09 –

CAMP-HL-10 0.31

CAMP-HL-11 –

CAMP-HL-12 0.65

CAMP-HL-13 0.14

CAMP-HL-14 –

CAMP-HL-15 0.34

Number of wells with detections 9

Detection frequency (percent) 60

GAMA well 

identification 

number

Perchlorate 

(μg/L) 

(63790)

Benchmark type MCL-CA

Benchmark level 6

[MRL] [0.10]

CAMP Cascade Range and 

Modoc Plateau Low Use Basins study area 

(15 grid wells sampled)

CAMP-LU-01 –

CAMP-LU-02 0.12

CAMP-LU-03 0.10

CAMP-LU-04 0.20

CAMP-LU-05 0.13

CAMP-LU-06 –

CAMP-LU-07 0.14

CAMP-LU-08 –

CAMP-LU-09 0.23

CAMP-LU-10 –

CAMP-LU-11 1.29

CAMP-LU-12 –

CAMP-LU-13 –

CAMP-LU-14 –

CAMP-LU-15 –

Number of wells with detections 7

Detection frequency (percent) 47

CAMP Quaternary Volcanic Areas study area (14 grid wells sampled)

CAMP-QV-01 –

CAMP-QV-02 –

CAMP-QV-03 –

CAMP-QV-04 –

CAMP-QV-05 –

CAMP-QV-06 0.21

CAMP-QV-07 –

CAMP-QV-08 –

CAMP-QV-09 –

CAMP-QV-10 0.13

CAMP-QV-11 0.11

CAMP-QV-12 –

CAMP-QV-13 –

CAMP-QV-15 –

Number of wells with detections 3

Detection frequency (percent) 21
Tables 69

Table 8. Results for analyses of perchlorate in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July 

through October 2010, California GAMA Priority Basin Project.—Continued

[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. 

Information about the analyte given in table 4C. Samples from 84 wells were analyzed for perchlorate (samples were not collected at wells CAMP-ES-01, 

-ES-02, -ES-03, -ES-04, -QV-14, and -TV-12). GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake 

Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; 

SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Minimum reporting level, benchmark 

type, and benchmark level as of January 10, 2012. 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. Other abbreviations: MRL, minimum reporting level; μg/L, micrograms per liter; –, not detected]]

GAMA well 

identification 

number

Perchlorate 

(μg/L) 

(63790)

Benchmark type MCL-CA

Benchmark level 6

[MRL] [0.10]

CAMP Shasta Valley and Mount Shasta Volcanic Area study area 

(15 grid wells sampled)

CAMP-SH-01 0.12

CAMP-SH-02 0.22

CAMP-SH-03 0.16

CAMP-SH-04 –

CAMP-SH-05 –

CAMP-SH-06 –

CAMP-SH-07 –

CAMP-SH-08 0.18

CAMP-SH-09 0.38

CAMP-SH-10 –

CAMP-SH-11 –

CAMP-SH-12 –

CAMP-SH-13 0.16

CAMP-SH-14 0.13

CAMP-SH-15 –

Number of wells with detections 7

Detection frequency (percent) 47

GAMA well 

identification 

number

Perchlorate 

(μg/L) 

(63790)

Benchmark type MCL-CA

Benchmark level 6

[MRL] [0.10]

CAMP Tertiary Volcanic Areas study area 

(14 grid wells sampled)

CAMP-TV-01 –

CAMP-TV-02 –

CAMP-TV-03 1 –

CAMP-TV-04 0.12

CAMP-TV-05 0.27

CAMP-TV-06 –

CAMP-TV-07 0.10

CAMP-TV-08 0.35

CAMP-TV-09 –

CAMP-TV-10 –

CAMP-TV-11 –

CAMP-TV-13 –

CAMP-TV-14 –

CAMP-TV-15 –

Number of wells with detections 4

Detection frequency (percent) 29

1

Conveyance from the TV-03 spring source to the point of use is an open 

channel.
70 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table 9. Nutrients detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through 

October 2010, California GAMA Priority Basin Project.

[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. 

Samples from 90 wells were analyzed. Information about the analytes given in table 4D. GAMA well identification number: ES, Sacramento Valley Eastside 

study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary 

Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. 

Benchmark type, and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method 

detection level; MDL, method detection level; mg/L, milligrams per liter; na, not available; –, not detected; *, value above benchmark]

GAMA well 

identification 

number

Ammonia, as 

nitrogen 

(mg/L) 

(00608)

 Nitrite,

as nitrogen 

(mg/L) 

(00613)

Nitrite 

plus nitrate, 

as nitrogen 

(mg/L) 

(00631)

Total nitrogen 

(ammonia + nitrate + 

nitrite + organic nitrogen) 

as nitrogen 

(mg/L) 

(62854) 2

Orthophosphate 

(as phosphorus) 

(mg/L) 

(00671)

Benchmark type HAL-US MCL-US MCL-US na na

Benchmark level 1

 24.7 1 10 na na

[LT-MDL] or [MDL] [0.01] [0.001] [0.02] [0.05] [0.004]

CAMP Sacramento Valley Eastside study area

CAMP-ES-01 – – 1.87 2.02 0.134

CAMP-ES-02 – – 1.04 1.07 0.083

CAMP-ES-03 – – 0.27 0.27 0.107

CAMP-ES-04 – – 0.25 0.27 0.072

CAMP-ES-05 – – 0.06 – 0.097

CAMP-ES-06 – – 0.07 0.07 0.103

CAMP-ES-07 – – 0.07 0.05 0.110

CAMP-ES-08 – – 0.09 0.07 0.112

CAMP-ES-09 – – 0.48 0.46 0.116

CAMP-ES-10 – – 0.19 0.19 0.112

CAMP-ES-11 – – 0.08 0.13 0.117

CAMP-ES-12 – 0.002 2.06 2.07 0.018

CAMP-ES-13 – – 1.64 1.68 0.065

CAMP-ES-14 – – 0.51 0.52 0.100

CAMP-ES-15 – – 0.47 0.49 0.107

CAMP Honey Lake Valley study area

CAMP-HL-01 – – 1.12 1.17 0.213

CAMP-HL-02 – – 0.20 0.19 0.032

CAMP-HL-03 – – 0.26 0.25 0.062

CAMP-HL-04 – – 0.77 0.77 0.100

CAMP-HL-05 – – 3.55 3.80 0.282

CAMP-HL-06 – – * 11.2 11.60 0.041

CAMP-HL-07 0.41 0.002 – 0.47 0.440

CAMP-HL-08 0.35 – – 0.43 1.030

CAMP-HL-09 0.40 0.007 0.03 0.41 0.077

CAMP-HL-10 0.06 – 0.94 1.07 0.086

CAMP-HL-11 2.42 0.011 1.65 4.31 0.319

CAMP-HL-12 – 0.001 3.93 4.01 0.091

CAMP-HL-13 – – 0.41 0.39 0.082

CAMP-HL-14 – – 0.26 0.25 0.110

CAMP-HL-15 – – 2.11 2.17 1.220

CAMP Cascade Range and Modoc Plateau Low Use Basins study area

CAMP-LU-01 1.13 – – 1.20 0.073

CAMP-LU-02 17.50 – – 19.70 0.366
Tables 71

Table 9. Nutrients detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through 

October 2010, California GAMA Priority Basin Project.—Continued

[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. 

Samples from 90 wells were analyzed. Information about the analytes given in table 4D. GAMA well identification number: ES, Sacramento Valley Eastside 

study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary 

Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. 

Benchmark type, and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method 

detection level; MDL, method detection level; mg/L, milligrams per liter; na, not available; –, not detected; *, value above benchmark]

GAMA well 

identification 

number

Ammonia, as 

nitrogen 

(mg/L) 

(00608)

 Nitrite,

as nitrogen 

(mg/L) 

(00613)

Nitrite 

plus nitrate, 

as nitrogen 

(mg/L) 

(00631)

Total nitrogen 

(ammonia + nitrate + 

nitrite + organic nitrogen) 

as nitrogen 

(mg/L) 

(62854) 2

Orthophosphate 

(as phosphorus) 

(mg/L) 

(00671)

Benchmark type HAL-US MCL-US MCL-US na na

Benchmark level 1

 24.7 1 10 na na

[LT-MDL] or [MDL] [0.01] [0.001] [0.02] [0.05] [0.004]

CAMP Cascade Range and Modoc Plateau Low Use Basins study area—Continued

CAMP-LU-03 – – 0.62 0.65 0.079

CAMP-LU-04 – – 2.31 2.35 0.048

CAMP-LU-05 – 0.001 0.97 1.03 0.071

CAMP-LU-06 0.64 0.001 – 0.75 0.551

CAMP-LU-07 – – 1.90 1.97 0.087

CAMP-LU-08 – – 0.09 0.07 0.053

CAMP-LU-09 – – 0.48 30.43 0.114

CAMP-LU-10 0.53 0.001 – 0.96 0.176

CAMP-LU-11 – – 2.25 2.25 0.173

CAMP-LU-12 – – 0.12 30.05 0.061

CAMP-LU-13 0.73 – – 0.83 0.149

CAMP-LU-14 – – 0.06 – 0.079

CAMP-LU-15 – – 0.43 0.40 0.032

CAMP Quaternary Volcanic Areas study area

CAMP-QV-01 – – 0.02 – 0.063

CAMP-QV-02 – – 0.10 0.07 0.049

CAMP-QV-03 0.04 – – – 0.182

CAMP-QV-04 0.11 0.011 0.14 0.45 0.194

CAMP-QV-05 0.01 – 0.11 0.11 0.042

CAMP-QV-06 – – 0.27 0.26 0.046

CAMP-QV-07 – – 0.06 – 0.036

CAMP-QV-08 – – 0.23 0.23 0.073

CAMP-QV-09 – – 0.21 0.21 0.031

CAMP-QV-10 – – 0.07 0.06 0.060

CAMP-QV-11 – – 0.17 0.16 0.046

CAMP-QV-12 – – 0.07 0.06 0.050

CAMP-QV-13 – – 0.07 0.05 0.093

CAMP-QV-14 – – 0.03 – 0.164

CAMP-QV-15 – – 0.18 0.16 0.056

CAMP Shasta Valley and Mount Shasta Volcanic Area study area

CAMP-SH-01 0.02 – 1.70 1.69 0.033

CAMP-SH-02 – – 2.18 2.15 0.247

CAMP-SH-03 – – 3.78 3.78 0.038

CAMP-SH-04 – – 0.09 3 – 0.187
72 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table 9. Nutrients detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through 

October 2010, California GAMA Priority Basin Project.—Continued

[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. 

Samples from 90 wells were analyzed. Information about the analytes given in table 4D. GAMA well identification number: ES, Sacramento Valley Eastside 

study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary 

Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. 

Benchmark type, and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method 

detection level; MDL, method detection level; mg/L, milligrams per liter; na, not available; –, not detected; *, value above benchmark]

GAMA well 

identification 

number

Ammonia, as 

nitrogen 

(mg/L) 

(00608)

 Nitrite,

as nitrogen 

(mg/L) 

(00613)

Nitrite 

plus nitrate, 

as nitrogen 

(mg/L) 

(00631)

Total nitrogen 

(ammonia + nitrate + 

nitrite + organic nitrogen) 

as nitrogen 

(mg/L) 

(62854) 2

Orthophosphate 

(as phosphorus) 

(mg/L) 

(00671)

Benchmark type HAL-US MCL-US MCL-US na na

Benchmark level 1

 24.7 1 10 na na

[LT-MDL] or [MDL] [0.01] [0.001] [0.02] [0.05] [0.004]

CAMP Shasta Valley and Mount Shasta Volcanic Area study area—Continued

CAMP-SH-05 – – 0.12 3 0.08 0.186

CAMP-SH-06 – – 0.15 0.12 0.081

CAMP-SH-07 – – 0.07 – 0.037

CAMP-SH-08 – – 0.70 0.69 0.120

CAMP-SH-09 – – 5.14 5.26 0.050

CAMP-SH-10 – – 0.39 0.41 0.181

CAMP-SH-11 – – 0.19 0.21 0.193

CAMP-SH-12 – – 7.04 7.33 0.322

CAMP-SH-13 – – 0.66 0.69 0.167

CAMP-SH-14 0.01 – 0.02 – 0.059

CAMP-SH-15 0.57 0.001 – 0.66 0.011

CAMP Tertiary Volcanic Areas study area

CAMP-TV-01 0.04 – 0.13 0.14 0.015

CAMP-TV-02 – – 0.23 3 0.19 0.086

CAMP-TV-03 4 – – 0.15 3 0.09 0.083

CAMP-TV-04 – 0.002 0.09 0.08 0.077

CAMP-TV-05 – – 0.44 0.45 0.064

CAMP-TV-06 – 0.001 0.10 0.10 0.028

CAMP-TV-07 – – 0.16 0.15 0.038

CAMP-TV-08 0.04 – 0.53 0.53 0.038

CAMP-TV-09 – – 0.06 – 0.055

CAMP-TV-10 0.01 – 0.40 0.39 0.022

CAMP-TV-11 – – 0.59 0.57 0.019

CAMP-TV-12 – – 0.09 0.08 0.044

CAMP-TV-13 – – 0.08 – 0.032

CAMP-TV-14 – – 0.65 0.67 0.013

CAMP-TV-15 – – – – 0.011

1

The HAL-US is 30 mg/L “as ammonia.” To facilitate comparson to the analytical results, this HAL-US has been converted and reported as 24.7 mg/L “as 

nitrogen.”

2

 Total nitrogen concentration was compared with the sum of ammonia concentration and nitrite plus nitrate concentration with the same criteria used to 

evaluate acceptability of replicates: for total nitrogen concentration greater than 0.25 μg/L (5 times LT-MDL), relative percent difference less than 10 percent 

indicates acceptable replication; for total nitrogen concentration less than or equal to 0.25 μg/L, standard deviation less than 0.025 μg/L (1/2 LT-MDL) indicates 

acceptable replication. For samples with total nitrogen concentration greater than the sum of ammonia and nitrite plus nitrate concentrations and unacceptable 

replication by these criteria, organic nitrogen is assumed to be present.

3

 Total nitrogen concentration is less than sum of ammonia and nitrite plus nitrate concentrations, and replication is considered unacceptable. However, the six 

samples all have total nitrogen concentration less than 0.5 μg/L, thus, the unacceptable replication is unlikely to affect interpretation of the data.

4

 Conveyance from the TV-03 spring source to the point of use is an open channel.
Tables 73

Table 10. Trace elements detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project. [The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 90 grid wells were analyzed. Information about the analytes given in table 4E. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method detection level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to; *, value above benchmark level; NWIS, USGS National Water Information System; NWQL, USGS National Water Quality Laboratory; BQS, USGS Branch of Quality Systems]

GAMA well 

identification 

number

Aluminum 

(μg/L) 

(01106) 

Antimony 

(μg/L) 

(01095) 

Arsenic 

(μg/L)

(01000) 

Barium 

(μg/L) 

(01005) 

Beryllium 

(μg/L) 

(01010)

Boron 1

(μg/L) 

(01020) 

Cadmium 

(μg/L) 

(01025) 

Chromium 

(μg/L)

 (01030) 

Cobalt 

(μg/L) 

(01035) 

Copper 

(μg/L) 

(01040) 

Iron 

(μg/L) 

(01046) 

Lead 

(μg/L) 

(01049) 

Benchmark type MCL-CA MCL-US MCL-US MCL-CA MCL-US NL-CA MCL-US MCL-CA na AL-US SMCL-CA AL-US

Benchmark level 1,000 6 10 1,000 4 1,000 5 50 na 1,300 300 15

[LT-MDL] or [SRL] [1.7] [0.027] [0.022] 2 [0.4] [0.006] [3] 3 [0.016] 2 [0.42] 3 [0.38] 2 [1.7] 2 [6] 3 [1.04]

CAMP Sacramento Valley Eastside study area

CAMP-ES-01 2.3 – 0.68 4 – 4 – 1.1 – ≤0.66 – ≤0.44

CAMP-ES-02 1.8 – 0.28 3 – 4 – 0.64 – 6.7 – ≤0.72

CAMP-ES-03 3.2 0.03 1.3 13 – 8 – 0.87 – ≤0.59 – ≤0.15

CAMP-ES-04 3.7 0.75 3.2 106 – 229 – ≤0.09 ≤0.04 3.9 – 2.62

CAMP-ES-05 2.9 0.03 0.33 3 – 5 – 3.1 – 1.8 – ≤0.60

CAMP-ES-06 2.5 – 0.43 5 – 4 – 0.49 – 1.9 – ≤0.33

CAMP-ES-07 2.7 0.04 0.75 6 – 4 – 1.0 ≤0.04 ≤1.7 – 1.10

CAMP-ES-08 2.4 – 0.51 9 – 5 – 1.1 – ≤0.80 ≤5 ≤0.15

CAMP-ES-09 3.3 – 0.86 19 – 19 – 0.65 – ≤1.6 – ≤0.53

CAMP-ES-10 2.7 – 0.39 10 – 7 – 1.0 – ≤1.5 – ≤0.15

CAMP-ES-11 2.4 – 0.31 5 – 4 – 0.48 – 2.3 – 1.31

CAMP-ES-12 1.9 – 0.04 2 – 5 – ≤0.25 ≤0.06 5.5 * 483 1.35

CAMP-ES-13 2.0 – 0.08 2 – 3 – 1.2 – ≤1.1 12 ≤0.20

CAMP-ES-14 2.8 0.04 0.85 19 – 8 – 1.0 – ≤0.77 – ≤0.66

CAMP-ES-15 2.6 – 0.79 9 – 45 – 0.75 – ≤0.76 ≤3 ≤0.34

CAMP Honey Lake Valley study area

CAMP-HL-01 13.3 0.13 8.7 6 – 201 – 3.4 – – ≤4 ≤0.35

CAMP-HL-02 – 0.05 2.7 45 – 3 – – – 2.5 16 1.29

CAMP-HL-03 – (4) 0.06 6.9 37 0.01 628 0.03 0.99 ≤0.02 – ≤5 ≤0.02

CAMP-HL-04 – 0.03 1.1 84 – 126 – 5.3 ≤0.02 ≤0.83 – 1.27

CAMP-HL-05 4.9 0.14 1.9 64 – 32 – ≤0.09 ≤0.02 – – ≤0.06

CAMP-HL-06 4.1 0.04 1.4 71 – 38 – ≤0.29 ≤0.05 ≤1.0 ≤6 ≤0.02

CAMP-HL-07 2.6 – 8.6 56 0.01 535 – – ≤0.03 – 92 ≤0.03

CAMP-HL-08 50.9 0.04 0.95 7 0.02 836 – ≤0.12 1.4 – 21 ≤0.15
74 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program Table 10. Trace elements detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project—Continued [The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 90 grid wells were analyzed. Information about the analytes given in table 4E. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method detection level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to; *, value above benchmark level; NWIS, USGS National Water Information System; NWQL, USGS National Water Quality Laboratory; BQS, USGS Branch of Quality Systems] GAMA well identification number Aluminum (μg/L) (01106) Antimony (μg/L) (01095) Arsenic (μg/L) (01000) Barium (μg/L) (01005) Beryllium (μg/L) (01010) Boron 1 (μg/L) (01020) Cadmium (μg/L) (01025) Chromium (μg/L) (01030) Cobalt (μg/L) (01035) Copper (μg/L) (01040) Iron (μg/L) (01046) Lead (μg/L) (01049) Benchmark type MCL-CA MCL-US MCL-US MCL-CA MCL-US NL-CA MCL-US MCL-CA na AL-US SMCL-CA AL-US Benchmark level 1,000 6 10 1,000 4 1,000 5 50 na 1,300 300 15 [LT-MDL] or [SRL] [1.7] [0.027] [0.022] 2 [0.4] [0.006] [3] 3 [0.016] 2 [0.42] 3 [0.38] 2 [1.7] 2 [6] 3 [1.04] CAMP Honey Lake Valley study area—Continued CAMP-HL-09 1.8 – 3.6 66 – 208 0.03 – ≤0.04 – 78 ≤0.69 CAMP-HL-10 – 0.04 3.2 54 – 237 – ≤0.09 ≤0.06 – * 383 ≤0.18 CAMP-HL-11 2.0 0.11 * 93.9 161 0.03 932 0.12 ≤0.32 ≤0.05 ≤0.68 25 ≤0.22 CAMP-HL-12 – 0.11 3.7 85 – 196 0.05 0.70 ≤0.05 ≤0.68 ≤4 ≤0.81 CAMP-HL-13 2.7 0.08 0.37 51 0.01 9 0.02 – – 4.3 – ≤0.13 CAMP-HL-14 1.9 0.03 6.1 108 0.01 530 – 0.43 ≤0.03 ≤0.70 ≤5 ≤0.04 CAMP-HL-15 2.8 0.48 * 199 33 0.02 917 0.04 1.9 ≤0.04 6.5 – ≤0.15 CAMP Cascade Range and Modoc Plateau Low Use Basins study area CAMP-LU-01 3.8 – 0.11 5 0.01 205 – – ≤0.03 – ≤5 ≤0.04 CAMP-LU-02 7.7 – 0.17 17 0.02 672 – ≤0.31 ≤0.10 2.7 * 325 1.12 CAMP-LU-03 3.5 0.03 4.0 9 – 83 – 1.1 ≤0.02 ≤0.73 – ≤0.22 CAMP-LU-04 2.3 0.05 1.3 4 – 30 – 1.3 ≤0.02 ≤1.3 ≤4 ≤0.26 CAMP-LU-05 2.3 0.03 5.8 88 – 83 0.02 1.4 ≤0.02 2.0 – ≤0.10 CAMP-LU-06 12.9 – 0.15 18 0.01 470 – ≤0.07 ≤0.23 ≤1.0 20 ≤0.36 CAMP-LU-07 2.4 – 0.28 4 – 11 – 2.4 ≤0.10 2.8 – ≤0.57 CAMP-LU-08 5.7 0.03 0.36 1 – 5 – ≤0.14 ≤0.11 2.5 – ≤0.14 CAMP-LU-09 4.3 – 3.9 17 – 60 – 0.81 ≤0.02 – 7 ≤0.08 CAMP-LU-10 4.8 – 0.49 7 – 94 – ≤0.08 ≤0.23 ≤1.1 235 ≤0.15 CAMP-LU-11 2.7 0.04 1.6 45 – 11 – 1.9 ≤0.03 ≤0.68 – ≤0.04 CAMP-LU-12 2.1 – 1.0 4 – 33 – 0.49 – – – ≤0.09 CAMP-LU-13 7.4 – 2.7 83 – 37 – – ≤0.03 ≤0.97 * 674 ≤0.04 CAMP-LU-14 1.8 0.04 2.0 5 – 20 – 0.71 – ≤0.95 – ≤0.12 CAMP-LU-15 2.8 – 0.75 10 – 13 – 1.3 – – – ≤0.10
Tables 75

Table 10. Trace elements detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority 

Basin Project—Continued 

[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 90 grid wells were analyzed. Information about the analytes given in table 4E. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method detection level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to; *, value above benchmark level; NWIS, USGS National Water Information System; NWQL, USGS National Water Quality Laboratory; BQS, USGS Branch of Quality Systems]

GAMA well 

identification 

number

Aluminum 

(μg/L) 

(01106) 

Antimony 

(μg/L) 

(01095) 

Arsenic 

(μg/L)

(01000) 

Barium 

(μg/L) 

(01005) 

Beryllium 

(μg/L) 

(01010)

Boron 1

(μg/L) 

(01020) 

Cadmium 

(μg/L) 

(01025) 

Chromium 

(μg/L)

 (01030) 

Cobalt 

(μg/L) 

(01035) 

Copper 

(μg/L) 

(01040) 

Iron 

(μg/L) 

(01046) 

Lead 

(μg/L) 

(01049) 

Benchmark type MCL-CA MCL-US MCL-US MCL-CA MCL-US NL-CA MCL-US MCL-CA na AL-US SMCL-CA AL-US

Benchmark level 1,000 6 10 1,000 4 1,000 5 50 na 1,300 300 15

[LT-MDL] or [SRL] [1.7] [0.027] [0.022] 2 [0.4] [0.006] [3] 3 [0.016] 2 [0.42] 3 [0.38] 2 [1.7] 2 [6] 3 [1.04]

CAMP Quaternary Volcanic Areas study area

CAMP-QV-01 2.3 – – 1 – – – – – ≤0.79 – ≤0.05

CAMP-QV-02 2.2 0.15 0.46 2 – 5 – ≤0.10 5.5 ≤1.2 – ≤0.03

CAMP-QV-03 4.9 – 0.35 82 – 29 – – – – 114 –

CAMP-QV-04 6.3 – 7.8 4 – 110 0.02 ≤0.12 ≤0.06 – 71 ≤0.02

CAMP-QV-05 14.6 – 0.16 2 – 4 – 1.0 – ≤0.67 – ≤0.18

CAMP-QV-06 8.7 0.11 3.6 1 – 22 – 0.90 – – ≤4 ≤0.32

CAMP-QV-07 5.5 – 0.07 2 – – – 0.55 – – – ≤0.06

CAMP-QV-08 2.1 0.03 0.77 12 – 36 – 1.0 – 3.7 – ≤0.06

CAMP-QV-09 5.0 – 0.09 3 – – – 1.6 – – – –

CAMP-QV-10 2.0 – 0.14 1 – 5 – 5.4 – 2.4 – ≤0.47

CAMP-QV-11 1.8 – 0.07 1 – – – 2.1 – ≤1.1 – ≤0.47

CAMP-QV-12 2.1 – – 0.8 – – – 8.9 – ≤1.3 ≤5 1.08

CAMP-QV-13 3.6 0.05 3.1 8 – 46 0.02 0.85 – 3.6 – ≤0.68

CAMP-QV-14 7.7 0.23 4.8 3 – 23 – 3.0 – – 23 ≤0.14

CAMP-QV-15 – – 0.58 2 – 43 – 1.4 – – ≤4 ≤0.07

CAMP Shasta Valley and Mount Shasta Volcanic Area study area

CAMP-SH-01 – – 0.04 26 – 10 – 0.45 ≤0.17 6.4 – ≤0.53

CAMP-SH-02 3.0 0.04 * 108 10 0.02 929 – 1.8 ≤0.07 4.6 ≤6 ≤0.53

CAMP-SH-03 2.5 0.05 0.73 49 – 52 – 8.4 ≤0.18 ≤1.3 – ≤1.04

CAMP-SH-04 1.8 0.04 3.3 3 – 82 0.02 0.47 – ≤0.56 – ≤0.09

CAMP-SH-05 5.5 0.04 0.90 3 – 12 – 0.69 ≤0.02 – 9 ≤0.03

CAMP-SH-06 2.8 – 0.41 4 – 16 – ≤0.26 – ≤1.2 – ≤0.22

CAMP-SH-07 1.8 – 0.05 0.8 – – – ≤0.10 – ≤1.4 – ≤0.23

CAMP-SH-08 2.0 – 2.4 6 – 36 – 0.52 – – – ≤0.07
76 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program Table 10. Trace elements detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project—Continued [The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 90 grid wells were analyzed. Information about the analytes given in table 4E. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method detection level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to; *, value above benchmark level; NWIS, USGS National Water Information System; NWQL, USGS National Water Quality Laboratory; BQS, USGS Branch of Quality Systems] GAMA well identification number Aluminum (μg/L) (01106) Antimony (μg/L) (01095) Arsenic (μg/L) (01000) Barium (μg/L) (01005) Beryllium (μg/L) (01010) Boron 1 (μg/L) (01020) Cadmium (μg/L) (01025) Chromium (μg/L) (01030) Cobalt (μg/L) (01035) Copper (μg/L) (01040) Iron (μg/L) (01046) Lead (μg/L) (01049) Benchmark type MCL-CA MCL-US MCL-US MCL-CA MCL-US NL-CA MCL-US MCL-CA na AL-US SMCL-CA AL-US Benchmark level 1,000 6 10 1,000 4 1,000 5 50 na 1,300 300 15 [LT-MDL] or [SRL] [1.7] [0.027] [0.022] 2 [0.4] [0.006] [3] 3 [0.016] 2 [0.42] 3 [0.38] 2 [1.7] 2 [6] 3 [1.04] CAMP Shasta Valley and Mount Shasta Volcanic Area study area—Continued CAMP-SH-09 – 0.03 0.28 31 – 117 – 1.4 ≤0.07 6.0 – 1.75 CAMP-SH-10 – 0.03 2.4 3 – 136 – ≤0.20 ≤0.07 4.9 – 2.12 CAMP-SH-11 1.7 – 2.5 3 – 110 – – ≤0.05 2.1 ≤4 ≤0.22 CAMP-SH-12 2.3 0.04 5.1 44 0.01 449 – 1.0 ≤0.13 5.8 – ≤0.75 CAMP-SH-13 3.4 0.03 4.6 7 0.01 150 – 0.72 ≤0.02 ≤0.88 – – CAMP-SH-14 3.0 – 0.04 3 – – – 2.1 – ≤1.3 23 ≤0.05 CAMP-SH-15 – – 0.28 126 0.01 444 – – ≤0.04 ≤0.64 19 ≤0.07 CAMP Tertiary Volcanic Areas study area CAMP-TV-01 2.8 – 3.9 13 0.12 * 5,520 0.12 0.51 ≤0.13 – ≤4 ≤0.04 CAMP-TV-02 16.2 0.05 3.3 6 – 62 – 0.89 ≤0.02 ≤0.89 20 ≤0.05 CAMP-TV-03 5 9.9 0.03 2.7 8 – 41 – 0.95 – 2.7 – ≤0.54 CAMP-TV-04 2.3 0.03 1.6 3 – 65 – 1.2 – – – ≤0.18 CAMP-TV-05 5.0 – 0.36 15 – 7 – 1.5 – – – ≤0.21 CAMP-TV-06 5.6 – 0.23 2 – 11 – 0.98 ≤0.02 ≤1.0 – 1.19 CAMP-TV-07 7.2 – 0.12 11 – 3 – ≤0.20 – ≤0.57 – ≤0.69 CAMP-TV-08 4.0 0.03 0.86 8 – 14 – 2.2 – – – ≤0.10 CAMP-TV-09 3.0 – 0.96 12 – 61 – 1.2 – ≤1.1 – ≤0.34 CAMP-TV-10 5.1 – – 6 – – – 0.87 – 2.6 – ≤0.94 CAMP-TV-11 – – – ≤0.4 – – – 3.3 – ≤1.3 – 1.53 CAMP-TV-12 – – 0.12 6 – 3 – 0.49 – – 8 ≤0.15 CAMP-TV-13 2.0 – 0.05 5 – 4 – 1.3 – 2.2 – ≤0.13 CAMP-TV-14 – – – – – – – 1.7 ≤0.02 2.5 10 ≤0.77 CAMP-TV-15 10.2 – 3.2 12 0.03 * 1,640 0.03 – (4) – ≤0.67 ≤4 ≤0.91
Tables 77

Table 10. Trace elements detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority 

Basin Project—Continued 

[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 90 grid wells were analyzed. Information about the analytes given in table 4E. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method detection level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to; *, value above benchmark level; NWIS, USGS National Water Information System; NWQL, USGS National Water Quality Laboratory; BQS, USGS Branch of Quality Systems]

GAMA well 

identification 

number

Lithium 

(μg/L) 

(01130) 

Manganese 

(μg/L) 

(01056) 

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)

Uranium 

(μg/L) 

(22703)

Vanadium 

(μg/L) 

(01085) 

Zinc 

(μg/L) 

(01090)

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

Benchmark level na 50 40 100 50 100 4,000 2 na 30 50 5,000

[LT-MDL] or [SRL] [0.22] 3 [0.7] [0.014] 2 [0.36] [0.03] [0.005] [0.2] [0.010] 2 [0.11] [0.004] 2 [0.10] 2 [4.8] 

CAMP Sacramento Valley Eastside study area

CAMP-ES-01 1.3 ≤0.7 0.1 2.40 0.18 – 121 – – 0.07 11.2 –

CAMP-ES-02 0.3 ≤0.2 0.1 0.39 – – 112 – – 0.03 11.7 ≤1.9

CAMP-ES-03 5.2 – 0.3 – 0.11 – 106 – ≤0.04 0.28 20.5 20.8

CAMP-ES-04 13.3 2.8 0.8 0.76 0.08 – 221 – ≤0.01 0.20 13.7 51.8

CAMP-ES-05 0.3 – 0.1 ≤0.33 – – 104 – ≤0.02 0.04 15.9 ≤2.5

CAMP-ES-06 0.9 ≤0.2 0.1 ≤0.30 0.03 – 119 – ≤0.02 0.11 19.2 16.5

CAMP-ES-07 1.5 – 0.1 ≤0.22 0.10 – 139 – ≤0.01 0.12 15.0 21.8

CAMP-ES-08 2.1 ≤0.2 0.1 0.59 0.07 – 132 – ≤0.01 0.14 11.6 ≤3.7

CAMP-ES-09 4.1 – 0.3 0.55 0.08 – 127 – ≤0.07 0.17 28.5 58.7

CAMP-ES-10 4.3 ≤0.4 0.2 0.54 0.04 – 143 – ≤0.01 0.04 19.3 10.8

CAMP-ES-11 0.8 – 0.1 ≤0.25 – – 122 – – 0.06 17.0 5.4

CAMP-ES-12 0.4 9.9 0.03 ≤0.25 – – 100 – 0.18 0.02 1.8 482

CAMP-ES-13 0.3 ≤0.2 0.03 ≤0.12 – – 128 – – 0.02 7.4 ≤3.0

CAMP-ES-14 1.6 – 0.3 ≤0.15 0.07 – 122 – ≤0.03 0.28 26.1 –

CAMP-ES-15 5.8 ≤0.3 0.2 ≤0.28 0.05 – 135 – ≤0.02 0.12 20.0 ≤2.0

CAMP Honey Lake Valley study area

CAMP-HL-01 3.4 ≤0.2 5.5 – 0.51 0.01 28.1 – 3.2 0.40 35.4 –

CAMP-HL-02 3.7 1.7 2.4 ≤0.11 0.04 – 136 – ≤0.04 1.69 5.7 8.8

CAMP-HL-03 5.1 11.5 12.5 ≤0.09 0.08 – 170 – 3.4 0.64 15.6 –

CAMP-HL-04 0.7 – 9.3 – 0.91 – 200 – ≤0.09 1.87 19.4 ≤1.7

CAMP-HL-05 – – 3.6 ≤0.09 1.0 – 226 – ≤0.03 0.53 12.9 –

CAMP-HL-06 7.9 ≤0.2 2.5 ≤0.27 0.18 – 223 – 0.75 0.93 3.8 –

CAMP-HL-07 1.8 * 102 7.4 ≤0.12 0.03 – 205 – 11.4 0.45 0.80 ≤1.9

CAMP-HL-08 0.6 8.2 3.2 ≤0.15 0.03 – 20.9 – 41.4 0.14 0.90 –
78 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program GAMA well identification number Lithium (μg/L) (01130) Manganese (μg/L) (01056) 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) Uranium (μg/L) (22703) Vanadium (μg/L) (01085) Zinc (μg/L) (01090) Benchmark type na SMCL-CA HAL-US MCL-CA MCL-US SMCL-CA HAL-US MCL-US na MCL-US NL-CA SMCL-CA Benchmark level na 50 40 100 50 100 4,000 2 na 30 50 5,000 [LT-MDL] or [SRL] [0.22] 3 [0.7] [0.014] 2 [0.36] [0.03] [0.005] [0.2] [0.010] 2 [0.11] [0.004] 2 [0.10] 2 [4.8] CAMP Honey Lake Valley study area—Continued CAMP-HL-09 33.9 * 196 10.7 – – – 222 – 1.1 0.06 0.15 10.4 CAMP-HL-10 52 * 182 5.7 ≤0.12 0.42 – 386 – 0.95 1.91 1.4 6.1 CAMP-HL-11 2.4 * 89.2 * 56.6 ≤0.22 1.8 – 278 – 3.2 * 35.8 19.1 12.5 CAMP-HL-12 3.4 ≤0.2 20.0 ≤0.21 1.8 – 389 – 0.93 * 34.2 17.2 8.5 CAMP-HL-13 11.8 – 1.1 – 0.21 0.01 209 – ≤0.03 1.37 1.6 ≤4.4 CAMP-HL-14 0.8 ≤0.4 3.8 ≤0.19 0.28 – 390 – 1.2 4.32 13.6 ≤2.0 CAMP-HL-15 4.6 ≤0.4 13.6 ≤0.29 1.5 – 80.7 – 15.7 5.01 * 146 8.2 CAMP Cascade Range and Modoc Plateau Low Use Basins study area CAMP-LU-01 1.6 10.3 3.9 ≤0.12 – – 78.5 – 0.46 –- – – CAMP-LU-02 29.7 28.1 1.4 0.55 – – 98.7 – 0.19 0.01 0.57 37.4 CAMP-LU-03 11.3 ≤0.6 2.3 – 0.35 – 98.0 – 0.28 0.99 15.6 ≤1.5 CAMP-LU-04 – – 0.4 – 0.13 – 157 – ≤0.05 0.86 7.9 – CAMP-LU-05 3.9 – 3.0 – 0.38 – 207 0.01 0.26 2.36 18.3 – CAMP-LU-06 17.4 14.1 5.0 ≤0.33 – – 4.59 – 5.7 0.01 0.17 ≤3.7 CAMP-LU-07 – ≤0.2 0.1 ≤0.27 0.49 – 142 – – 0.84 12.9 ≤3.1 CAMP-LU-08 4.2 ≤0.2 0.1 – – – 40.4 – ≤0.02 0.03 4.0 7.8 CAMP-LU-09 22.8 0.8 2.3 – 0.44 – 65.6 – ≤0.07 1.76 13.8 12.3 CAMP-LU-10 5.0 * 166 3.6 ≤0.28 0.04 – 202 – 0.11 0.01 0.70 52.7 CAMP-LU-11 2.5 – 0.7 ≤0.12 0.15 – 118 – ≤0.02 0.55 31.6 ≤3.8 CAMP-LU-12 6.0 – 2.3 – 0.03 – 73.4 – ≤0.03 0.19 7.9 – CAMP-LU-13 1.3 * 461 2.8 ≤0.12 – – 155 – ≤0.07 –- 0.12 6.9 CAMP-LU-14 7.5 – 0.5 – – – 52.9 – ≤0.05 0.26 6.9 – CAMP-LU-15 1.3 – 0.2 – – – 73.0 – ≤0.02 0.61 2.8 ≤2.4 Table 10. Trace elements detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project—Continued [The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 90 grid wells were analyzed. Information about the analytes given in table 4E. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method detection level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to; *, value above benchmark level; NWIS, USGS National Water Information System; NWQL, USGS National Water Quality Laboratory; BQS, USGS Branch of Quality Systems]
Tables 79

GAMA well 

identification 

number

Lithium 

(μg/L) 

(01130) 

Manganese 

(μg/L) 

(01056) 

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)

Uranium 

(μg/L) 

(22703)

Vanadium 

(μg/L) 

(01085) 

Zinc 

(μg/L) 

(01090)

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

Benchmark level na 50 40 100 50 100 4,000 2 na 30 50 5,000

[LT-MDL] or [SRL] [0.22] 3 [0.7] [0.014] 2 [0.36] [0.03] [0.005] [0.2] [0.010] 2 [0.11] [0.004] 2 [0.10] 2 [4.8] 

CAMP Quaternary Volcanic Areas study area

CAMP-QV-01 – – 0.03 – – – 24.8 – – –- 7.5 ≤2.1

CAMP-QV-02 3.9 7.8 0.2 0.70 – – 41.7 0.01 ≤0.04 0.06 11.7 ≤2.9

CAMP-QV-03 0.5 * 144 5.6 – – – 88.0 – 0.22 –- – –

CAMP-QV-04 5.3 * 67.7 13.0 0.48 0.15 – 107 – 0.16 0.45 26.6 24.3

CAMP-QV-05 0.9 – 0.4 – – 0.01 66.5 – ≤0.04 0.33 5.5 ≤2.1

CAMP-QV-06 1.5 ≤0.4 1.9 – 0.15 – 24.1 – 0.41 0.55 29.4 –

CAMP-QV-07 0.5 – 0.1 – – – 67.4 – – 0.16 2.8 –

CAMP-QV-08 2.0 – 0.7 – 0.05 – 57.3 – ≤0.05 0.56 9.6 –

CAMP-QV-09 0.5 – 0.2 – – – 78.8 – ≤0.01 0.42 3.2 –

CAMP-QV-10 – – 0.04 ≤0.09 – – 99.4 0.01 – 0.04 9.4 8.5

CAMP-QV-11 – – – – – – 79.0 – – 0.02 8.2 ≤2.5

CAMP-QV-12 – ≤0.2 – – – – 54.7 – – 0.01 8.7 –

CAMP-QV-13 7.3 – 1.6 ≤0.20 0.04 – 86.9 – ≤0.05 0.32 11.9 24.9

CAMP-QV-14 4.6 1.0 2.4 – 0.09 – 14.5 0.02 0.66 0.08 29.6 12.3

CAMP-QV-15 2.4 ≤0.4 2.1 – 0.03 – 66.3 – ≤0.02 0.10 7.6 ≤1.4

CAMP Shasta Valley and Mount Shasta Volcanic Area study area

CAMP-SH-01 5.8 ≤0.2 0.1 1.00 0.13 – 388 – – 0.95 0.23 8.7

CAMP-SH-02 39.9 5.2 0.5 0.80 0.90 – 170 – ≤0.06 1.45 31.1 39.7

CAMP-SH-03 1.4 ≤0.6 0.4 1.10 0.30 – 332 – ≤0.01 1.22 2.5 ≤3.6

CAMP-SH-04 22.0 – 1.4 – 0.08 – 66.1 0.01 ≤0.03 0.09 25.4 –

CAMP-SH-05 16.4 – 0.4 – 0.03 – 52.7 – ≤0.05 0.14 * 54.3 –

CAMP-SH-06 5.5 ≤0.3 0.2 – – – 44.6 – ≤0.02 0.10 9.8 72

CAMP-SH-07 0.9 – 0.1 – – – 42.9 – – 0.04 7.3 37.9

CAMP-SH-08 14.0 – 0.8 – 0.10 – 173 – ≤0.02 0.30 13.8 –

Table 10. Trace elements detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority 

Basin Project—Continued 

[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 90 grid wells were analyzed. Information about the analytes given in table 4E. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method detection level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to; *, value above benchmark level; NWIS, USGS National Water Information System; NWQL, USGS National Water Quality Laboratory; BQS, USGS Branch of Quality Systems]
80 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program GAMA well identification number Lithium (μg/L) (01130) Manganese (μg/L) (01056) 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) Uranium (μg/L) (22703) Vanadium (μg/L) (01085) Zinc (μg/L) (01090) Benchmark type na SMCL-CA HAL-US MCL-CA MCL-US SMCL-CA HAL-US MCL-US na MCL-US NL-CA SMCL-CA Benchmark level na 50 40 100 50 100 4,000 2 na 30 50 5,000 [LT-MDL] or [SRL] [0.22] 3 [0.7] [0.014] 2 [0.36] [0.03] [0.005] [0.2] [0.010] 2 [0.11] [0.004] 2 [0.10] 2 [4.8] CAMP Shasta Valley and Mount Shasta Volcanic Area study area—Continued CAMP-SH-09 1.8 – 0.3 ≤0.31 0.09 – 296 – – 1.29 1.1 ≤4.7 CAMP-SH-10 50.5 ≤0.2 1.0 ≤0.32 0.04 – 121 – ≤0.02 0.21 21.1 8.9 CAMP-SH-11 54.5 ≤0.2 1.4 0.55 – – 104 – ≤0.03 0.14 20.4 ≤2.9 CAMP-SH-12 11.6 – 1.0 0.91 0.16 – 523 – ≤0.07 4.70 36.3 5.4 CAMP-SH-13 12.1 – 0.6 0.41 0.09 – 132 – ≤0.03 0.46 20.5 – CAMP-SH-14 0.7 1.4 0.02 ≤0.13 – – 307 – – 0.03 3.0 ≤2.6 CAMP-SH-15 23.7 * 186 0.9 0.62 0.05 – 2,430 – 0.99 1.96 0.76 ≤3.4 CAMP Tertiary Volcanic Areas study area CAMP-TV-01 95.2 4.8 * 41.0 0.55 0.18 – 207 – 0.44 0.21 7.4 5.5 CAMP-TV-02 4.3 ≤0.2 0.9 ≤0.15 0.15 – 62.6 – ≤0.07 0.23 11.0 15.8 CAMP-TV-03 5 6.6 – 1.3 0.37 0.03 – 82.5 – ≤0.03 0.28 11.3 5.9 CAMP-TV-04 – – 1.0 – 0.05 – 161 – 0.12 0.09 16.0 6.5 CAMP-TV-05 0.8 – 0.5 ≤0.13 0.06 – 93.4 – ≤0.08 0.6 10.9 14.4 CAMP-TV-06 0.6 ≤0.2 0.2 – – – 56.6 – ≤0.02 0.37 3.1 61 CAMP-TV-07 0.3 ≤0.2 0.1 – – – 163 – ≤0.02 0.33 4.7 5.6 CAMP-TV-08 1.6 – 1.0 – 0.08 – 47.7 – 0.17 0.42 17.4 7.8 CAMP-TV-09 1.3 – 0.3 – 0.04 – 219 – ≤0.01 1.62 7.2 ≤2.1 CAMP-TV-10 0.5 1.0 – ≤0.17 – – 92.4 – – 0.01 0.29 15.1 CAMP-TV-11 – – – – – – 35.9 – – –- 1.9 ≤4.5 CAMP-TV-12 1.1 ≤0.2 0.04 – – – 72.4 – – 0.07 4.9 32.7 CAMP-TV-13 0.8 ≤0.2 0.02 ≤0.14 – – 93.5 – – 0.08 2.0 5.0 CAMP-TV-14 – 1.0 – ≤0.13 – – 11.5 – – –- 0.74 21.2 CAMP-TV-15 2.0 3.2 9.0 – – – 12.3 – 1.3 0.02 0.46 – Table 10. Trace elements detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project—Continued [The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 90 grid wells were analyzed. Information about the analytes given in table 4E. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method detection level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to; *, value above benchmark level; NWIS, USGS National Water Information System; NWQL, USGS National Water Quality Laboratory; BQS, USGS Branch of Quality Systems]
Tables 81

Table 10. Trace elements detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority 

Basin Project—Continued 

[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 90 grid wells were analyzed. Information about the analytes given in table 4E. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method detection level; SRL, study reporting level; μg/L, micrograms per liter; na, not available; –, not detected; ≤, less than or equal to; *, value above benchmark level; NWIS, USGS National Water Information System; NWQL, USGS National Water Quality Laboratory; BQS, USGS Branch of Quality Systems]Footnotes:

1 Results from the USGS Branch of Quality Systems Quality Assurance project during the time period that the CAMP study unit samples were analyzed at the NWQL (mid-August through November 2010) 

indicate that boron results with concentrations less than approximately 60 μg/L may have analytical bias, see the appendix for more information.

2 SRL defined based on examination of GAMA quality-control samples collected from May 2004 through January 2008 (Olsen and others, 2010). Values below the SRL are reported as ≤ the value reported 

by the laboratory. In the USGS NWIS database, the result is accompanied with the following comment: Result is < or = reported value, based on QC data (may include: field blanks, source-solution blanks, trip blanks, NWQL set blanks, NWQL blank water certificates, and USGS BQS Blind Blank Program data).

3 SRL defined as the highest concentration detected in field blanks collected for the CAMP study unit. Values below the SRL are reported as less than or equal to (≤) the value reported by the laboratory. In the 

USGS NWIS database, the result is accompanied with the following comment: Result is ≤ reported value, based on quality-control data collected for this study.

4 MDL raised by the laboratory (aluminum had a raised MDL of 3.4 for HL-03; chromium had a raised MDL of 0.09 for TV-15).5 Conveyance from the TV-03 spring source to the point of use is an open channel.
82 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program Table 11. Major and minor ions, silica, and total dissolved solids (TDS) detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project. [The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from 90 wells were analyzed. Information about the analytes given in table 4F. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method detection level; MRL, method reporting level; mg/L, milligrams per liter; SiO2, silicon dioxide; na, not available; –, not detected; *, value above benchmark level; **, value above upper benchmark level] GAMA well 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) Silica (as SiO2) (mg/L) (00955) Sodium (mg/L) (00930) Sulfate (mg/L) (00945) Total dissolved solids (TDS) (mg/L) (70300) Benchmark type na na SMCL-CA MCL-CA na na na na na SMCL-CA SMCL-CA Benchmark level na na 1 250 (500) 2 na na na na na 1 250 (500) 1 500 (1,000) [LT-MDL] [0.010] [0.022] [0.06] [0.04] [0.0010] [0.008] [0.032] [0.029] [0.06] [0.09] [12] CAMP Sacramento Valley Eastside study area CAMP-ES-01 0.02 20.2 2.92 – – 11.9 1.27 55.1 5.9 1.40 165 CAMP-ES-02 0.02 15.6 2.46 – – 9.68 1.77 69.3 5.8 0.23 168 CAMP-ES-03 0.01 17.8 0.96 0.07 – 13.0 1.63 64.9 11.3 1.05 173 CAMP-ES-04 0.03 27.0 7.79 0.10 0.009 19.1 2.30 44.8 22.9 10.8 232 CAMP-ES-05 – 15.3 0.93 – – 9.35 1.64 63.9 5.0 0.36 147 CAMP-ES-06 – 20.5 0.96 – – 9.44 1.83 61.6 6.2 0.39 171 CAMP-ES-07 – 20.6 1.03 0.06 – 10.4 1.93 63.2 7.4 1.28 171 CAMP-ES-08 – 17.2 1.03 – – 10.7 1.84 64.0 7.9 0.57 152 CAMP-ES-09 – 20.4 1.49 0.06 – 17.4 1.66 64.4 11.2 0.64 221 CAMP-ES-10 – 21.7 1.23 0.06 – 11.2 1.25 72.6 7.5 0.38 188 CAMP-ES-11 – 20.2 1.09 – – 8.41 1.53 63.7 6.2 0.37 185 CAMP-ES-12 – 14.4 3.11 – – 6.87 1.39 47.2 5.5 0.19 141 CAMP-ES-13 0.02 20.0 4.68 – – 10.2 1.10 64.7 6.8 0.56 182 CAMP-ES-14 – 20.2 2.05 0.09 – 13.5 2.45 63.9 7.8 0.87 184 CAMP-ES-15 – 17.7 3.26 0.13 – 10.3 1.13 64.0 9.3 3.40 173 CAMP Honey Lake Valley study area CAMP-HL-01 0.10 2.66 18.5 0.29 – 0.935 3.44 39.0 75.9 28.8 252 CAMP-HL-02 0.02 16.5 1.44 0.24 0.002 2.96 2.13 19.9 20.9 19.8 129 CAMP-HL-03 0.11 27.0 41.1 0.28 0.008 10.1 4.31 52.8 71.9 119 393 CAMP-HL-04 0.05 24.6 4.32 0.21 0.001 10.3 2.14 58.1 63.2 81.0 351 CAMP-HL-05 0.04 23.8 8.34 0.28 0.004 8.97 1.91 47.1 21.2 14.3 217 CAMP-HL-06 0.02 27.3 18.9 0.07 0.001 6.60 2.95 36.8 19.0 7.64 219 CAMP-HL-07 0.46 16.5 162 0.51 0.020 9.96 5.43 34.5 213 74.5 * 733 CAMP-HL-08 0.06 1.11 19.0 1.08 0.016 0.529 1.60 32.7 252 22.8 * 710
Tables 83

Table 11. Major and minor ions, silica, and total dissolved solids (TDS) detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from 90 wells were analyzed. Information about the analytes given in table 4F. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc 

Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method detection level; MRL, method reporting level; mg/L, milligrams per liter; SiO2, silicon dioxide; na, not available; –, not 

detected; *, value above benchmark level; **, value above upper benchmark level]

GAMA well 

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) 

Silica 

(as SiO2) 

(mg/L) 

(00955) 

Sodium 

(mg/L) 

(00930) 

Sulfate 

(mg/L) 

(00945) 

Total dissolved 

solids

(TDS) 

(mg/L) 

(70300)

Benchmark type na na SMCL-CA MCL-CA na na na na na SMCL-CA SMCL-CA

Benchmark level na na 1 250 (500) 2 na na na na na 1 250 (500) 1 500 (1,000)

[LT-MDL] [0.010] [0.022] [0.06] [0.04] [0.0010] [0.008] [0.032] [0.029] [0.06] [0.09] [12]

CAMP Honey Lake Valley study area—Continued

CAMP-HL-09 0.09 30.3 15.0 0.35 0.001 9.56 5.39 56.1 50.5 62.2 323

CAMP-HL-10 0.12 46.1 25.9 0.46 – 18.4 8.42 53.1 70.9 143 490

CAMP-HL-11 0.22 32.7 58.0 0.65 0.028 14.7 9.42 50.5 193 166 * 771

CAMP-HL-12 0.07 65.4 17.5 0.27 0.002 28.9 2.98 34.9 60.1 216 * 545

CAMP-HL-13 0.02 17.6 3.33 0.23 – 4.46 0.84 49.4 17.9 2.62 149

CAMP-HL-14 0.30 52.3 34.4 0.24 0.010 22.9 13.0 58.1 107 181 * 776

CAMP-HL-15 0.20 7.70 29.8 1.51 0.018 3.17 3.79 51.5 256 77.3 * 622

CAMP Cascade Range and Modoc Plateau Low Use Basins study area

CAMP-LU-01 0.04 6.05 7.38 0.20 0.005 2.53 14.2 31.4 58.2 1.30 217

CAMP-LU-02 0.21 11.9 45.5 0.23 0.011 18.7 7.13 45.9 121 5.96 472

CAMP-LU-03 0.07 20.1 5.96 0.21 0.002 3.26 9.51 76.7 41.5 20.1 266

CAMP-LU-04 0.01 33.8 5.24 0.04 – 8.72 0.89 22.9 13.4 9.49 188

CAMP-LU-05 0.06 30.4 6.05 0.19 – 6.56 8.41 65.7 30.6 20.4 274

CAMP-LU-06 0.04 0.52 9.43 0.53 0.005 0.200 6.20 75.8 77.8 19.3 286

CAMP-LU-07 0.08 22.7 2.23 0.11 0.001 14.2 2.27 38.5 8.9 13.1 165

CAMP-LU-08 – 4.61 0.21 0.05 – 1.40 1.63 47.4 4.3 0.34 82

CAMP-LU-09 0.10 7.88 8.26 0.17 0.002 1.17 8.59 67.3 57.2 15.3 254

CAMP-LU-10 0.08 67.0 12.4 0.30 0.017 70.8 12.9 23.3 91.9 33.2 * 676

CAMP-LU-11 0.03 15.0 3.35 0.23 – 8.92 4.96 65.1 12.1 4.23 170

CAMP-LU-12 – 10.4 0.68 0.06 – 7.00 2.54 42.4 7.0 2.31 110

CAMP-LU-13 0.03 21.8 9.31 0.27 0.005 12.9 3.32 59.4 32.5 14.9 244

CAMP-LU-14 – 7.70 0.49 – – 6.12 2.64 36.2 6.2 0.46 77

CAMP-LU-15 0.01 16.4 1.44 – – 6.72 2.12 32.7 5.6 0.57 108
84 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program Table 11. Major and minor ions, silica, and total dissolved solids (TDS) detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued [The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from 90 wells were analyzed. Information about the analytes given in table 4F. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method detection level; MRL, method reporting level; mg/L, milligrams per liter; SiO2, silicon dioxide; na, not available; –, not detected; *, value above benchmark level; **, value above upper benchmark level] GAMA well 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) Silica (as SiO2) (mg/L) (00955) Sodium (mg/L) (00930) Sulfate (mg/L) (00945) Total dissolved solids (TDS) (mg/L) (70300) Benchmark type na na SMCL-CA MCL-CA na na na na na SMCL-CA SMCL-CA Benchmark level na na 1 250 (500) 2 na na na na na 1 250 (500) 1 500 (1,000) [LT-MDL] [0.010] [0.022] [0.06] [0.04] [0.0010] [0.008] [0.032] [0.029] [0.06] [0.09] [12] CAMP Quaternary Volcanic Areas study area CAMP-QV-01 – 3.52 0.18 – – 1.14 0.65 23.8 1.9 0.22 54 CAMP-QV-02 – 3.58 0.21 0.07 – 0.930 1.40 33.4 2.9 0.18 64 CAMP-QV-03 0.05 15.5 5.42 0.18 0.006 4.89 9.14 69.8 39.1 17.6 240 CAMP-QV-04 0.10 36.1 20.6 0.37 0.009 44.9 11.4 23.7 95.1 98.8 * 563 CAMP-QV-05 – 10.1 0.55 – – 5.88 1.74 31.0 5.4 0.36 84 CAMP-QV-06 0.02 9.62 1.41 0.13 – 1.10 3.36 51.2 21.5 3.62 138 CAMP-QV-07 – 9.08 0.25 – – 4.80 1.44 28.4 3.9 – 71 CAMP-QV-08 – 11.7 1.28 0.06 – 7.75 2.56 39.2 7.9 2.10 121 CAMP-QV-09 – 13.6 0.96 – – 7.73 1.75 26.8 5.0 0.81 109 CAMP-QV-10 – 21.1 0.89 – – 16.1 0.67 56.9 6.5 0.31 183 CAMP-QV-11 – 22.2 1.14 – – 10.4 0.66 52.2 5.7 0.43 166 CAMP-QV-12 – 15.8 1.05 – – 11.0 0.33 58.0 4.4 0.32 149 CAMP-QV-13 – 12.1 1.00 0.04 – 10.4 3.02 54.1 10.3 2.48 150 CAMP-QV-14 – 1.79 0.68 0.22 – 1.24 1.99 45.4 14.8 0.45 95 CAMP-QV-15 – 11.6 0.80 – – 7.56 2.28 39.8 8.6 2.13 117 CAMP Shasta Valley and Mount Shasta Volcanic Area study area CAMP-SH-01 0.02 72.5 3.83 0.14 – 9.26 0.63 25.5 9.0 8.44 269 CAMP-SH-02 0.07 19.4 26.7 0.20 0.004 45.3 1.34 65.3 30.5 15.7 336 CAMP-SH-03 0.02 67.5 5.41 0.10 – 24.3 1.56 29.4 11.7 21.4 323 CAMP-SH-04 0.04 7.03 8.75 0.33 – 6.38 1.19 56.8 18.3 1.36 141 CAMP-SH-05 – 5.21 0.62 0.27 – 4.14 1.30 53.7 10.1 1.28 109 CAMP-SH-06 – 6.36 1.13 0.07 – 4.08 1.81 51.7 7.4 0.28 104 CAMP-SH-07 – 5.48 0.14 – – 1.02 1.37 33.2 2.9 0.16 62 CAMP-SH-08 0.02 15.8 6.80 0.23 0.001 13.5 1.83 64.1 19.2 9.49 166 CAMP-SH-09 0.06 56.6 15.0 0.14 0.001 21.7 1.34 29.2 18.7 12.8 306
Tables 85

Table 11. Major and minor ions, silica, and total dissolved solids (TDS) detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from 90 wells were analyzed. Information about the analytes given in table 4F. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc 

Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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: LT-MDL, long-term method detection level; MRL, method reporting level; mg/L, milligrams per liter; SiO2, silicon dioxide; na, not available; –, not 

detected; *, value above benchmark level; **, value above upper benchmark level]

GAMA well 

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) 

Silica 

(as SiO2) 

(mg/L) 

(00955) 

Sodium 

(mg/L) 

(00930) 

Sulfate 

(mg/L) 

(00945) 

Total dissolved 

solids

(TDS) 

(mg/L) 

(70300)

Benchmark type na na SMCL-CA MCL-CA na na na na na SMCL-CA SMCL-CA

Benchmark level na na 1 250 (500) 2 na na na na na 1 250 (500) 1 500 (1,000)

[LT-MDL] [0.010] [0.022] [0.06] [0.04] [0.0010] [0.008] [0.032] [0.029] [0.06] [0.09] [12]

CAMP Shasta Valley and Mount Shasta Volcanic Area study area—Continued

CAMP-SH-10 0.03 17.5 9.70 0.40 0.003 22.8 1.83 60.6 21.8 7.08 251

CAMP-SH-11 0.02 15.2 6.56 0.41 0.007 21.2 1.50 63.2 20.0 6.45 219

CAMP-SH-12 0.09 61.0 23.2 0.26 0.010 46.8 5.78 56.9 59.4 45.3 * 570

CAMP-SH-13 0.04 16.1 9.88 0.22 0.001 14.6 2.09 48.6 18.4 5.46 179

CAMP-SH-14 – 10.4 0.48 – – 5.30 1.62 59.7 6.8 0.10 125

CAMP-SH-15 0.17 79.2 94.1 0.45 0.022 36.7 2.23 15.1 115 54.0 * 626

CAMP Tertiary Volcanic Areas study area

CAMP-TV-01 1.03 58.5 ** 687 0.60 0.092 1.08 0.93 18.9 445 91.5 ** 1,380

CAMP-TV-02 0.01 10.6 2.95 0.08 – 6.83 2.42 34.9 11.8 2.33 114

CAMP-TV-03 2 – 12.6 1.04 0.06 – 10.8 2.98 55.8 9.1 2.40 151

CAMP-TV-04 0.01 7.69 3.14 0.11 – 5.85 2.52 44.5 9.9 1.08 112

CAMP-TV-05 0.01 12.7 2.21 0.07 – 10.0 4.47 57.9 12.5 0.60 164

CAMP-TV-06 – 10.7 0.57 – – 6.06 1.76 22.2 4.2 0.18 85

CAMP-TV-07 – 17.3 0.48 0.04 – 8.02 3.89 33.6 6.9 0.22 132

CAMP-TV-08 0.01 9.94 1.41 0.09 – 4.27 3.92 35.6 18.1 0.96 126

CAMP-TV-09 0.02 24.3 6.32 – – 22.1 1.97 31.3 7.7 2.01 191

CAMP-TV-10 – 10.2 0.73 – – 7.07 0.88 23.6 2.4 – 80

CAMP-TV-11 – 11.7 0.29 – – 6.98 0.35 25.9 2.3 – 94

CAMP-TV-12 – 12.6 0.66 – – 7.12 1.16 37.6 4.0 0.22 98

CAMP-TV-13 – 14.0 0.50 – – 9.46 1.15 38.0 3.6 0.14 118

CAMP-TV-14 – 3.78 0.42 – – 4.73 0.15 20.7 1.0 0.14 54

CAMP-TV-15 0.04 2.01 14.4 0.60 0.008 0.083 0.27 11.7 65.9 10.3 170

1 The SMCL-CAs for chloride, sulfate, and total dissolved solids (TDS) have recommended and upper benchmark levels. The benchmark level is shown in parentheses.2 Conveyance from the TV-03 spring source to the point of use is an open channel.
86 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table 12. Uranium isotopes detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through 

October 2010, California GAMA Priority Basin Project.

[The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent 

or property. Samples from 20 grid wells were analyzed, and all results are reported. Values less than the sample-specific critical level (ssLC) are reported as 

non-detections (–). Table 4G contains additional information about the constituents. GAMA well identification number: HL, Honey Lake Valley study area 

grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic 

Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. Benchmark type: MCL-CA, California Department of Public Health 

maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level. Other abbreviations: CSU, 1-sigma combined 

standard uncertainty; pCi/L, picocuries per liter; ±, plus or minus; *, value above benchmark level]

GAMA well 

identification number

Uranium-234 

(pCi/L) 

(22610)

Uranium-235 

(pCi/L) 

(22620)

Uranium-238 

(pCi/L) 

(22603)

Benchmark type1 MCL-CA MCL-CA MCL-CA

Benchmark level 2 20 2

 20 2 20

Reporting level method result ± CSU ssLC result ± CSU ssLC result ± CSU ssLC

CAMP Honey Lake Valley study area

CAMP-HL-05 0.239 ± 0.033 0.020 0.019 ± 0.015 0.016 0.152 ± 0.025 0.013

CAMP-HL-06 0.455 ± 0.063 0.026 – 0.023 0.306 ± 0.052 0.022

CAMP-HL-07 0.143 ± 0.034 0.028 – 0.025 0.198 ± 0.042 0.019

CAMP-HL-08 0.056 ± 0.028 0.025 0.026 ± 0.017 0.008 0.056 ± 0.021 0.017

CAMP-HL-11 * 16.20 ± 0.73 0.031 * 0.618 ± 0.055 0.011 * 10.40 ± 0.48 0.028

CAMP-HL-12 * 14.30 ± 0.67 0.033 * 0.58 ± 0.060 0.014 * 10.00 ± 0.48 0.030

CAMP-HL-14 2.20 ± 0.13 0.019 0.088 ± 0.019 0.016 1.46 ± 0.095 0.013

CAMP-HL-15 2.76 ± 0.15 0.020 0.098 ± 0.021 0.012 1.70 ± 0.10 0.015

CAMP Quaternary Volcanic Areas study area

CAMP-QV-07 0.140 ± 0.027 0.017 – 0.015 0.070 ± 0.018 0.012

CAMP-QV-08 0.340 ± 0.043 0.020 0.022 ± 0.011 0.015 0.201 ± 0.033 0.012

CAMP Shasta Valley and Mount Shasta Volcanic Area study area

CAMP-SH-01 1.260 ± 0.090 0.020 0.062 ± 0.019 0.015 0.287 ± 0.037 0.016

CAMP-SH-02 0.828 ± 0.064 0.018 0.053 ± 0.017 0.015 0.512 ± 0.046 0.013

CAMP-SH-03 1.090 ± 0.082 0.017 0.020 ± 0.010 0.015 0.398 ± 0.045 0.013

CAMP-SH-04 0.070 ± 0.020 0.020 – 0.019 – 0.015

CAMP-SH-05 0.054 ± 0.027 0.032 – 0.024 0.045 ± 0.027 0.027

CAMP-SH-06 0.079 ± 0.029 0.032 – 0.020 0.100 ± 0.029 0.019

CAMP-SH-07 – 0.025 – 0.020 – 0.014

CAMP Tertiary Volcanic Areas study area

CAMP-TV-01 0.170 ± 0.027 0.017 – 0.014 0.073 ± 0.017 0.010

CAMP-TV-04 0.089 ± 0.025 0.019 – 0.017 0.040 ± 0.015 0.015

CAMP-TV-05 0.358 ± 0.047 0.018 – 0.019 0.219 ± 0.036 0.016

1

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.

2

The MCL-US benchmark for uranium is the sum of uranium-234, uranium-235, and uranium-238.
Tables 87

Table 13. Radon-222 detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through 

October 2010, California GAMA Priority Basin Project.

[The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent 

or property. Samples from 90 grid wells were analyzed. Values less than the sample-specific critical level (ssLC) are reported as non-detections (–). Information 

about the analytes given in table 4G. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study 

area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta 

Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type, and benchmark level as of 

January 10, 2012. 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. 

Other abbreviations: CSU, 1-sigma combined standard uncertainty; pCi/L, picocuries per liter; ±, plus or minus; nc, not collected; *, value above benchmark 

level]

GAMA well 

identification number

Radon-222 

(pCi/L) 

(82303)

Benchmark type Proposed MCL-US

Benchmark level 4,000

Reporting level method Result ± CSU ssLC

CAMP Sacramento Valley Eastside study area

CAMP-ES-01 149 ± 13 12.26

CAMP-ES-02 124 ± 12 12.59

CAMP-ES-03 109 ± 12 13.61

CAMP-ES-04 350 ± 23 11.56

CAMP-ES-05 104 ± 11 11.15

CAMP-ES-06 141 ± 13 11.53

CAMP-ES-07 173 ± 15 13.37

CAMP-ES-08 70.0 ± 9.4 11.32

CAMP-ES-09 98 ± 10 11.08

CAMP-ES-10 20.0 ± 8.1 12.48

CAMP-ES-11 103 ± 11 12.39

CAMP-ES-12 370 ± 24 11.83

CAMP-ES-13 163 ± 14 11.78

CAMP-ES-14 108 ± 11 10.54

CAMP-ES-15 101 ± 12 13.45

CAMP Honey Lake Valley study area

CAMP-HL-01 420 ± 27 12.60

CAMP-HL-02 1,520 ± 89 25.32

CAMP-HL-03 410 ± 32 24.86

CAMP-HL-04 390 ± 29 21.56

CAMP-HL-05 380 ± 25 13.10

CAMP-HL-06 1,080 ± 62 12.79

CAMP-HL-07 460 ± 29 11.31

CAMP-HL-08 410 ± 26 12.21

CAMP-HL-09 280 ± 21 13.78

CAMP-HL-10 970 ± 56 13.58

CAMP-HL-11 800 ± 47 12.59

CAMP-HL-12 1,040 ± 60 12.25

CAMP-HL-13 * 5,100 ± 280 31.26

CAMP-HL-14 370 ± 33 30.94

CAMP-HL-15 258 ± 19 12.91

GAMA well 

identification number

Radon-222 

(pCi/L) 

(82303)

Benchmark type Proposed MCL-US

Benchmark level 4,000

Reporting level method Result ± CSU ssLC

CAMP Cascade Range and Modoc Plateau 

Low Use Basins study area

CAMP-LU-01 420 ± 27 11.89

CAMP-LU-02 46.0 ± 8.4 11.30

CAMP-LU-03 430 ± 28 12.49

CAMP-LU-04 930 ± 54 12.15

CAMP-LU-05 600 ± 39 18.93

CAMP-LU-06 610 ± 40 18.41

CAMP-LU-07 15.0 ± 8.8 13.75

CAMP-LU-08 230 ± 20 17.99

CAMP-LU-09 470 ± 30 13.77

CAMP-LU-10 66.0 ± 9.8 12.19

CAMP-LU-11 870 ± 51 13.33

CAMP-LU-12 740 ± 46 18.15

CAMP-LU-13 192 ± 16 13.55

CAMP-LU-14 520 ± 33 13.92

CAMP-LU-15 390 ± 26 13.95

CAMP Quaternary Volcanic Areas study area

CAMP-QV-01 138 ± 13 12.96

CAMP-QV-02 220 ± 20 18.26

CAMP-QV-03 640 ± 39 13.25

CAMP-QV-04 111 ± 12 12.10

CAMP-QV-05 61 ± 10 13.48

CAMP-QV-06 600 ± 40 21.08

CAMP-QV-07 440 ± 28 12.86

CAMP-QV-08 430 ± 28 12.89

CAMP-QV-09 460 ± 29 13.30

CAMP-QV-10 214 ± 16 12.06

CAMP-QV-11 225 ± 17 12.32

CAMP-QV-12 480 ± 31 13.72

CAMP-QV-13 380 ± 25 13.40

CAMP-QV-14 970 ± 56 12.12

CAMP-QV-15 1,540 ± 85 11.47
88 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table 13. Radon-222 detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through 

October 2010, California GAMA Priority Basin Project.—Continued

[The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent 

or property. Samples from 90 grid wells were analyzed. Values less than the sample-specific critical level (ssLC) are reported as non-detections (–). Information 

about the analytes given in table 4G. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study 

area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta 

Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type, and benchmark level as of 

January 10, 2012. 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. 

Other abbreviations: CSU, 1-sigma combined standard uncertainty; pCi/L, picocuries per liter; ±, plus or minus; nc, not collected; *, value above benchmark 

level]

GAMA well 

identification number

Radon-222 

(pCi/L) 

(82303)

Benchmark type Proposed MCL-US

Benchmark level 4,000

Reporting level method Result ± CSU ssLC

CAMP Shasta Valley and Mount Shasta Volcanic Area study area

CAMP-SH-01 1,410 ± 79 12.31

CAMP-SH-02 51.0 ± 9.6 13.05

CAMP-SH-03 830 ± 49 12.84

CAMP-SH-04 121 ± 12 12.45

CAMP-SH-05 219 ± 17 12.48

CAMP-SH-06 560 ± 34 10.90

CAMP-SH-07 220 ± 16 10.86

CAMP-SH-08 790 ± 46 12.06

CAMP-SH-09 940 ± 55 13.85

CAMP-SH-10 134 ± 13 13.03

CAMP-SH-11 75 ± 10 12.88

CAMP-SH-12 213 ± 17 13.02

CAMP-SH-13 112 ± 11 11.14

CAMP-SH-14 320 ± 22 11.96

CAMP-SH-15 480 ± 30 10.66

GAMA well 

identification number

Radon-222 

(pCi/L) 

(82303)

Benchmark type Proposed MCL-US

Benchmark level 4,000

Reporting level method Result ± CSU ssLC

CAMP Tertiary Volcanic Areas study area

CAMP-TV-01 126 ± 12 11.98

CAMP-TV-02 103 ± 11 12.62

CAMP-TV-03 1 230 ± 20 18.45

CAMP-TV-04 280 ± 20 13.58

CAMP-TV-05 270 ± 20 13.54

CAMP-TV-06 620 ± 38 13.38

CAMP-TV-07 320 ± 21 11.58

CAMP-TV-08 70 ± 10 13.31

CAMP-TV-09 930 ± 53 11.54

CAMP-TV-10 350 ± 23 11.40

CAMP-TV-11 450 ± 28 12.14

CAMP-TV-12 360 ± 24 12.30

CAMP-TV-13 770 ± 45 11.38

CAMP-TV-14 300 ± 21 12.96

CAMP-TV-15 1,610 ± 90 12.61

1

 Conveyance from the TV-03 spring source to the point of use is an open channel.
Tables 89

Table 14. Gross alpha and gross beta particle activities detected in samples collected for the Cascade Range and Modoc Plateau 

(CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.

[The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent 

or property. Samples from 90 grid wells were analyzed. Information about the analytes given in table 4G. The reference nuclide for measurement of gross alpha 

is thorium-230, and the reference nuclide for measurement of gross beta is cesium-137. Measured values less than the sample-specific critical level (ssLC) are 

reported as non-detections (–). GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area 

grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley 

and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 

2012. 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. Other 

abbreviations: CSU, 1-sigma combined standard uncertainty; pCi/L, picocurie per liter; ±, plus or minus; *, value above benchmark level]

GAMA 

well 

identification 

number

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 radioactivity, 

30-day count 

(pCi/L) 

(62645)

Benchmark type MCL-US MCL-US MCL-CA MCL-CA

Benchmark level 15 15 50 50

Reporting level method Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC

CAMP Sacramento Valley Eastside study area

CAMP-ES-01 – 0.57 0.70 ± 0.41 0.47 – 0.62 – 0.98

CAMP-ES-02 – 0.48 – 0.42 1.30 ± 0.41 0.63 2.04 ± 0.61 0.96

CAMP-ES-03 – 0.67 – 1.0 2.22 ± 0.66 1.1 1.20 ± 0.60 0.92

CAMP-ES-04 – 1.1 – 1.1 3.62 ± 0.63 0.79 2.38 ± 0.71 1.0

CAMP-ES-05 – 0.71 – 0.61 1.40 ± 0.50 0.67 – 0.87

CAMP-ES-06 – 0.46 1.03 ± 0.61 0.65 0.90 ± 0.40 0.63 – 0.88

CAMP-ES-07 – 0.62 0.50 ± 0.37 0.46 1.72 ± 0.45 0.66 1.53 ± 0.43 0.62

CAMP-ES-08 – 0.36 – 0.59 1.30 ± 0.30 0.44 1.21 ± 0.41 0.61

CAMP-ES-09 – 0.35 – 0.46 1.15 ± 0.36 0.55 1.14 ± 0.42 0.63

CAMP-ES-10 1.08 ± 0.39 0.26 – 0.76 1.89 ± 0.61 0.96 1.30 ± 0.60 0.85

CAMP-ES-11 0.41 ± 0.28 0.30 0.50 ± 0.20 0.17 1.20 ± 0.60 0.96 1.08 ± 0.29 0.44

CAMP-ES-12 – 0.54 – 0.68 0.92 ± 0.38 0.58 1.15 ± 0.55 0.84

CAMP-ES-13 – 0.47 – 0.86 – 0.77 – 0.87

CAMP-ES-14 1.12 ± 0.49 0.52 – 0.76 2.40 ± 0.46 0.62 2.13 ± 0.71 1.1

CAMP-ES-15 1.07 ± 0.51 0.59 – 0.76 0.92 ± 0.41 0.62 1.60 ± 0.70 1.1

CAMP Honey Lake Valley study area

CAMP-HL-01 1.49 ± 0.77 0.89 0.87 ± 0.56 0.67 3.32 ± 0.53 0.69 3.00 ± 0.50 0.65

CAMP-HL-02 3.61 ± 0.62 0.39 3.63 ± 0.62 0.44 1.31 ± 0.31 0.45 2.95 ± 0.36 0.44

CAMP-HL-03 1.07 ± 0.51 0.64 1.54 ± 0.62 0.70 4.32 ± 0.55 0.74 3.04 ± 0.53 0.75

CAMP-HL-04 2.70 ± 0.80 0.84 1.74 ± 0.58 0.61 1.63 ± 0.44 0.66 1.86 ± 0.56 0.86

CAMP-HL-05 1.14 ± 0.44 0.52 – 0.50 1.82 ± 0.33 0.46 1.64 ± 0.32 0.45

CAMP-HL-06 1.96 ± 0.46 0.38 – 0.42 2.86 ± 0.41 0.55 3.43 ± 0.43 0.55

CAMP-HL-07 – 2.2 2.1 ± 1.1 1.5 1 4.63 ± 0.61 0.78 4.30 ± 0.60 0.89

CAMP-HL-08 – 1.5 – 1.5 1 1.29 ± 0.39 0.58 – 0.86

CAMP-HL-09 – 0.76 2 0.87 ± 0.61 0.69 5.25 ± 0.52 0.57 2 4.25 ± 0.64 0.85

CAMP-HL-10 5.0 ± 1.1 0.85 1.64 ± 0.77 1.00 8.27 ± 0.88 1.0 8.04 ± 0.75 0.78

CAMP-HL-11 * 46.0 ± 5.7 1.7 *,3 38.0 ± 5.0 1.4 1 12.00 ± 0.86 0.6 20.2 ± 1.3 0.59

CAMP-HL-12 *,3 27.4 ± 3.5 1.1 *,3 26.0 ± 3.3 0.83 5.24 ± 0.76 0.94 15.4 ± 1.3 1.4

CAMP-HL-13 3.98 ± 0.69 0.42 1.64 ± 0.53 0.48 1.07 ± 0.35 0.54 1.89 ± 0.66 0.98

CAMP-HL-14 4.7 ± 1.2 1.3 3.8 ± 1.6 1.6 13.6 ± 1.1 0.85 15.7 ± 1.4 1.2

CAMP-HL-15 1 10.0 ± 2.0 1.4 6.2 ± 1.7 1.6 1 3.90 ± 0.73 1.0 3.85 ± 0.73 1.1
90 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

GAMA 

well 

identification 

number

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 radioactivity, 

30-day count 

(pCi/L) 

(62645)

Benchmark type MCL-US MCL-US MCL-CA MCL-CA

Benchmark level 15 15 50 50

Reporting level method Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC

CAMP Cascade Range and Modoc Plateau Low Use Basins study area

CAMP-LU-01 – 0.68 – 0.68 13.20 ± 0.97 0.66 13.30 ± 0.98 0.62

CAMP-LU-02 1.98 ± 0.78 0.90 – 1.3 4.85 ± 0.84 1.2 7.22 ± 0.94 1.2

CAMP-LU-03 2.30 ± 0.60 0.54 3.03 ± 0.91 0.81 9.12 ± 0.68 0.53 9.61 ± 0.84 0.78

CAMP-LU-04 2.60 ± 0.57 0.53 1.06 ± 0.56 0.66 0.73 ± 0.31 0.47 3.51 ± 0.77 1.1

CAMP-LU-05 4.24 ± 0.78 0.44 2.67 ± 0.71 0.63 7.78 ± 0.64 0.57 8.12 ± 0.66 0.59

CAMP-LU-06 1.47 ± 0.47 0.39 – 0.58 6.23 ± 0.55 0.56 5.88 ± 0.55 0.56

CAMP-LU-07 1.51 ± 0.57 0.56 1.10 ± 0.50 0.53 1.62 ± 0.45 0.65 1.91 ± 0.45 0.64

CAMP-LU-08 – 0.47 – 0.35 1.42 ± 0.51 0.80 0.80 ± 0.38 0.59

CAMP-LU-09 1.40 ± 0.67 0.75 0.70 ± 0.50 0.62 7.15 ± 0.68 0.67 7.02 ± 0.67 0.66

CAMP-LU-10 – 1.3 – 1.6 1 11.30 ± 0.83 0.64 9.95 ± 0.78 0.69

CAMP-LU-11 – 0.49 1.00 ± 0.50 0.57 4.28 ± 0.53 0.60 4.70 ± 0.56 0.63

CAMP-LU-12 1 1.74 ± 0.58 0.52 0.99 ± 0.46 0.51 1 2.30 ± 0.52 0.73 0.96 ± 0.47 0.72

CAMP-LU-13 0.81 ± 0.39 0.47 – 0.56 2.25 ± 0.35 0.46 2.86 ± 0.49 0.64

CAMP-LU-14 0.49 ± 0.31 0.38 0.68 ± 0.34 0.36 1.32 ± 0.41 0.60 1.96 ± 0.43 0.6

CAMP-LU-15 0.98 ± 0.47 0.56 1.31 ± 0.46 0.41 1.50 ± 0.40 0.57 1.91 ± 0.51 0.75

CAMP Quaternary Volcanic Areas study area

CAMP-QV-01 – 0.22 0.59 ± 0.31 0.37 – 0.42 1.20 ± 0.50 0.79

CAMP-QV-02 – 0.32 0.46 ± 0.28 0.35 0.84 ± 0.38 0.59 1.30 ± 0.40 0.58

CAMP-QV-03 – 0.69 – 0.58 7.16 ± 0.72 0.79 7.19 ± 0.63 0.56

CAMP-QV-04 – 1.4 – 1.3 1 10.00 ± 0.72 0.52 10.10 ± 0.73 0.55

CAMP-QV-05 0.64 ± 0.25 0.28 0.66 ± 0.36 0.42 0.98 ± 0.34 0.52 1.71 ± 0.42 0.60

CAMP-QV-06 – 0.44 0.50 ± 0.30 0.41 3.11 ± 0.35 0.41 3.00 ± 0.35 0.41

CAMP-QV-07 0.62 ± 0.24 0.27 – 0.44 1.32 ± 0.31 0.45 1.40 ± 0.60 0.93

CAMP-QV-08 0.78 ± 0.26 0.25 – 0.52 2.41 ± 0.33 0.41 2.48 ± 0.43 0.57

CAMP-QV-09 4 0.58 ± 0.29 0.38 – 0.39 1.33 ± 0.27 0.40 1.57 ± 0.42 0.60

CAMP-QV-10 – 0.49 – 0.50 – 0.61 – 0.63

CAMP-QV-11 – 0.61 0.24 ± 0.19 0.18 – 0.62 – 0.63

CAMP-QV-12 – 0.45 – 0.67 – 0.63 – 0.89

CAMP-QV-13 – 0.59 – 0.86 2.44 ± 0.46 0.62 2.16 ± 0.61 0.87

CAMP-QV-14 – 0.46 – 0.71 2.33 ± 0.52 0.75 1.20 ± 0.70 1.0

CAMP-QV-15 – 0.52 – 0.67 1.90 ± 0.66 0.96 2.22 ± 0.61 0.87

CAMP Shasta Valley and Mount Shasta Volcanic Area study area

CAMP-SH-01 1.78 ± 0.43 0.38 1.11 ± 0.56 0.66 – 0.45 6.26 ± 0.69 0.85

CAMP-SH-02 2.30 ± 0.60 0.55 1.06 ± 0.66 0.84 0.86 ± 0.35 0.54 1.29 ± 0.49 0.74

CAMP-SH-03 1.51 ± 0.62 0.75 1.04 ± 0.56 0.69 – 0.92 0.90 ± 0.48 0.75

Table 14. Gross alpha and gross beta particle activities detected in samples collected for the Cascade Range and Modoc Plateau 

(CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued

[The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent 

or property. Samples from 90 grid wells were analyzed. Information about the analytes given in table 4G. The reference nuclide for measurement of gross alpha 

is thorium-230, and the reference nuclide for measurement of gross beta is cesium-137. Measured values less than the sample-specific critical level (ssLC) are 

reported as non-detections (–). GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area 

grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley 

and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 

10, 2012. 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. Other 

abbreviations: CSU, 1-sigma combined standard uncertainty; pCi/L, picocurie per liter; ±, plus or minus; *, value above benchmark level]
Tables 91

Table 14. Gross alpha and gross beta particle activities detected in samples collected for the Cascade Range and Modoc Plateau 

(CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued

[The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent 

or property. Samples from 90 grid wells were analyzed. Information about the analytes given in table 4G. The reference nuclide for measurement of gross alpha 

is thorium-230, and the reference nuclide for measurement of gross beta is cesium-137. Measured values less than the sample-specific critical level (ssLC) are 

reported as non-detections (–). GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area 

grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley 

and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 

10, 2012. 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. Other 

abbreviations: CSU, 1-sigma combined standard uncertainty; pCi/L, picocurie per liter; ±, plus or minus; *, value above benchmark level]

GAMA 

well 

identification 

number

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 radioactivity, 

30-day count 

(pCi/L) 

(62645)

Benchmark type MCL-US MCL-US MCL-CA MCL-CA

Benchmark level 15 15 50 50

Reporting level method Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC

CAMP Shasta Valley and Mount Shasta Volcanic Area study area—Continued

CAMP-SH-04 – 0.34 – 0.55 – 0.44 – 0.62

CAMP-SH-05 – 0.39 – 0.48 1.42 ± 0.28 0.39 0.96 ± 0.39 0.6

CAMP-SH-06 – 0.36 – 0.40 1.82 ± 0.33 0.45 1.84 ± 0.42 0.6

CAMP-SH-07 0.27 ± 0.18 0.24 – 0.45 1.57 ± 0.43 0.66 0.85 ± 0.36 0.55

CAMP-SH-08 – 0.50 – 0.45 1.10 ± 0.50 0.78 1.59 ± 0.42 0.64

CAMP-SH-09 2.94 ± 0.67 0.49 – 1.1 1.32 ± 0.46 0.72 1.67 ± 0.66 1.0

CAMP-SH-10 0.75 ± 0.44 0.46 – 0.64 2.24 ± 0.48 0.66 1.10 ± 0.70 1.1

CAMP-SH-11 0.65 ± 0.37 0.38 1.47 ± 0.57 0.58 0.80 ± 0.40 0.62 0.90 ± 0.40 0.61

CAMP-SH-12 1 2.97 ± 0.95 0.99 3.10 ± 0.96 0.99 4.68 ± 0.79 1.1 7.16 ± 0.72 0.74

CAMP-SH-13 0.83 ± 0.56 0.69 4.84 ± 0.94 0.54 2.44 ± 0.49 0.67 6.00 ± 0.60 0.60

CAMP-SH-14 – 0.39 – 0.51 0.95 ± 0.27 0.40 1.60 ± 0.39 0.56

CAMP-SH-15 8.8 ± 1.7 0.93 3.1 ± 1.2 1.4 1 3.03 ± 0.67 0.96 2.96 ± 0.62 0.89

CAMP Tertiary Volcanic Areas study area

CAMP-TV-01 – 4.2 – 2.8 1 – 1.2 – 1.1

CAMP-TV-02 – 0.50 – 0.54 1.68 ± 0.42 0.60 1.87 ± 0.51 0.76

CAMP-TV-03 5 1 1.36 ± 0.48 0.45 – 0.48 1 2.16 ± 0.51 0.75 1.86 ± 0.42 0.61

CAMP-TV-04 – 0.44 – 0.28 3.61 ± 0.52 0.65 1.89 ± 0.31 0.42

CAMP-TV-05 – 0.51 0.50 ± 0.32 0.41 3.70 ± 0.53 0.67 4.41 ± 0.42 0.44

CAMP-TV-06 – 0.34 0.38 ± 0.29 0.37 1.08 ± 0.29 0.42 1.95 ± 0.42 0.59

CAMP-TV-07 0.63 ± 0.28 0.32 0.56 ± 0.27 0.22 3.09 ± 0.35 0.41 3.02 ± 0.47 0.62

CAMP-TV-08 0.45 ± 0.35 0.43 – 0.52 3.15 ± 0.48 0.61 3.91 ± 0.51 0.61

CAMP-TV-09 1.92 ± 0.63 0.64 0.84 ± 0.46 0.51 2.18 ± 0.56 0.85 2.52 ± 0.57 0.85

CAMP-TV-10 – 0.45 – 0.34 – 0.55 0.77 ± 0.46 0.72

CAMP-TV-11 – 0.46 – 0.71 – 0.56 – 0.80

CAMP-TV-12 – 0.46 – 0.65 0.66 ± 0.38 0.60 – 1.3

CAMP-TV-13 – 0.54 – 0.78 1.17 ± 0.55 0.95 0.96 ± 0.55 0.85

CAMP-TV-14 – 0.33 – 0.48 – 0.93 1.24 ± 0.55 0.81

CAMP-TV-15 1.06 ± 0.37 0.39 0.99 ± 0.48 0.47 – 0.55 0.70 ± 0.40 0.62

1

 72-hour holding time exceeded by 1 to 4 days. Activity in sample may be greater than reported activity. Note replicate results for gross beta, 72-hour from 

QV-04, were within acceptable ranges.

2

 30-day holding time exceeded by 35 days. Activity in sample may be greater than reported activity.

3

 The MCL-US for gross alpha activity applies to adjusted gross alpha, which is measured gross alpha activity minus uranium activity. Adjusted gross alpha 

activities for HL-11, 30-day count, and HL-12, 72-hour and 30-day counts, were lower than the MCL-US.

4

 Data for QV-09 are stored in the USGS NWIS database under the following parameter codes: 63014, gross alpha, 72-hour; 63016, gross alpha, 30-day; 63015, 

gross beta, 72-hour; 63017, gross beta, 30-day.

5

 Conveyance from the TV-03 spring source to the point of use is an open channel.
92 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table 15. Results for analyses of species of inorganic arsenic and iron in samples collected for the Cascade Range and Modoc 

Plateau (CAMP) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, July through October 2010, California GAMA 

Priority Basin Project.

[Data in this table were analyzed at U.S. Geological Survey (USGS) Trace Metals Laboratory for the purpose of determining ratios of oxidized and reduced 

species of arsenic and iron. Information about the analytes given in table 4H. Absolute concentrations may be less accurate than those in table 10. GAMA well 

identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc 

Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study 

area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type, and benchmark level as of January 10, 2012. 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. Other abbreviations: MDL, method detection 

limit; na, not available; μg/L, micrograms per liter; na, not available; nc, not collected; –, not detected; ≤, less than or equal to; *, value above benchmark level]

GAMA well

identification

number

Arsenic 

(total) 

(μg/L) 

Arsenic 

(III) 

(μg/L) 

Iron 

(total) 

(μg/L) 

Iron 

(II) 

(μg/L) 

Benchmark type MCL-US na SMCL-CA na

Benchmark level 10 na 300 na

[MDL] [0.15] [0.5] 1 [6] [2]

CAMP Sacramento Valley Eastside study area

CAMP-ES-01 0.62 – – – (2)

CAMP-ES-02 0.24 – – – (2)

CAMP-ES-03 1.2 – – – (2)

CAMP-ES-04 3.2 – ≤2.7 2.7

CAMP-ES-05 0.32 – – –

CAMP-ES-06 0.43 – – – (2)

CAMP-ES-07 0.79 – ≤2.5 –

CAMP-ES-08 0.46 – ≤2.2 –

CAMP-ES-09 0.79 – – – (2)

CAMP-ES-10 nc nc nc nc

CAMP-ES-11 0.22 – – – (2)

CAMP-ES-12 – – * 489 44

CAMP-ES-13 – – – – (2)

CAMP-ES-14 0.81 – – – (2)

CAMP-ES-15 0.73 – – –

CAMP Honey Lake Valley study area

CAMP-HL-01 9.1 – ≤3.7 –

CAMP-HL-02 2.6 – ≤4.0 4.0

CAMP-HL-03 7.7 – ≤3.8 3.4

CAMP-HL-04 1.2 – – – (2)

CAMP-HL-05 2.1 – – – (2)

CAMP-HL-06 1.5 – 6.7 5.6

CAMP-HL-07 8.5 6.3 98 95

CAMP-HL-08 0.70 0.7 14.0 14

CAMP-HL-09 3.9 2.2 81 –

CAMP-HL-10 3.4 – * 405 360

CAMP-HL-11 * 63 1.2 26 24

CAMP-HL-12 3.9 – ≤2.5 2.4

CAMP-HL-13 0.29 – – – (2)

CAMP-HL-14 6.32 – – – (2)

CAMP-HL-15 * 187 2.9 ≤2.5 –

CAMP Cascade Range and Modoc Plateau Low Use Basins study area

CAMP-LU-01 – – ≤5.4 5.0

CAMP-LU-02 – – * 319 319

CAMP-LU-03 3.5 – ≤2.8 2.8
Tables 93

GAMA well

identification

number

Arsenic 

(total) 

(μg/L) 

Arsenic 

(III) 

(μg/L) 

Iron 

(total) 

(μg/L) 

Iron 

(II) 

(μg/L) 

Benchmark type MCL-US na SMCL-CA na

Benchmark level 10 na 300 na

[MDL] [0.15] [0.5] 1 [6] [2]

CAMP Cascade Range and Modoc Plateau Low Use Basins study area—Continued

CAMP-LU-04 1.0 – – – (2)

CAMP-LU-05 5.6 – – – (2)

CAMP-LU-06 – – 17 17

CAMP-LU-07 0.23 – – – (2)

CAMP-LU-08 0.33 – – – (2)

CAMP-LU-09 4.1 – 8.4 3.8

CAMP-LU-10 0.17 – 248 208

CAMP-LU-11 1.1 – – – (2)

CAMP-LU-12 0.76 – – – (2)

CAMP-LU-13 2.5 – * 620 2.2

CAMP-LU-14 2.1 – – – (2)

CAMP-LU-15 0.75 – – – (2)

CAMP Quaternary Volcanic Areas study area

CAMP-QV-01 – – – – (2)

CAMP-QV-02 0.47 – – – (2)

CAMP-QV-03 0.37 – 154 128

CAMP-QV-04 7.5 2.7 75 69

CAMP-QV-05 – – ≤4.3 –

CAMP-QV-06 4.0 – ≤3.9 –

CAMP-QV-07 – – – – (2)

CAMP-QV-08 0.89 – – – (2)

CAMP-QV-09 – – – – (2)

CAMP-QV-10 – – – – (2)

CAMP-QV-11 – – – – (2)

CAMP-QV-12 – – ≤5.6 –

CAMP-QV-13 3.2 – – – (2)

CAMP-QV-14 4.8 – 22 4.0

CAMP-QV-15 0.56 – ≤3.7 2.5

CAMP Shasta Valley and Mount Shasta Volcanic Area study area

CAMP-SH-01 – (3) – (3) – – (3)

CAMP-SH-02 * 101 2.0 ≤2.5 2.3

CAMP-SH-03 0.55 – (3) ≤4.1 4.1

CAMP-SH-04 3.7 – (3) – –

CAMP-SH-05 0.98 – (3) – –

CAMP-SH-06 – (3) – (3) – –

CAMP-SH-07 – (3) – (3) – –

Table 15. Results for analyses of species of inorganic arsenic and iron in samples collected for the Cascade Range and Modoc 

Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued

[Data in this table were analyzed at U.S. Geological Survey (USGS) Trace Metals Laboratory for the purpose of determining ratios of oxidized and reduced 

species of arsenic and iron. Information about the analytes given in table 4H. Absolute concentrations may be less accurate than those in table 10. GAMA well 

identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc 

Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study 

area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type, and benchmark level as of January 10, 2012. 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. Other abbreviations: MDL, method detection 

limit; na, not available; μg/L, micrograms per liter; na, not available; nc, not collected; –, not detected; ≤, less than or equal to; *, value above benchmark level]
94 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

GAMA well

identification

number

Arsenic 

(total) 

(μg/L) 

Arsenic 

(III) 

(μg/L) 

Iron 

(total) 

(μg/L) 

Iron 

(II) 

(μg/L) 

Benchmark type MCL-US na SMCL-CA na

Benchmark level 10 na 300 na

[MDL] [0.15] [0.5] 1 [6] [2]

CAMP Shasta Valley and Mount Shasta Volcanic Area study area—Continued

CAMP-SH-08 2.5 – – – (2)

CAMP-SH-09 0.23 – – – (2)

CAMP-SH-10 2.5 – ≤2.8 –

CAMP-SH-11 2.5 – – – (2)

CAMP-SH-12 5.3 – – – (2)

CAMP-SH-13 4.8 – – – (2)

CAMP-SH-14 – – 25 19

CAMP-SH-15 0.25 – 22 18

CAMP Tertiary Volcanic Areas study area

CAMP-TV-01 2.5 – (3) ≤2.7 2.7

CAMP-TV-02 2.9 – 9.8 9.8

CAMP-TV-03 4 2.4 – ≤4.4 3.8

CAMP-TV-04 1.8 – – – (2)

CAMP-TV-05 0.40 – – – (2)

CAMP-TV-06 0.19 – – – (2)

CAMP-TV-07 – – – – (2)

CAMP-TV-08 0.90 – – – (2)

CAMP-TV-09 0.98 – – – (2)

CAMP-TV-10 – – ≤2.2 –

CAMP-TV-11 – – – – (2)

CAMP-TV-12 – – 7.5 6.5

CAMP-TV-13 – – – – (2)

CAMP-TV-14 – – 9.6 3.9

CAMP-TV-15 3.0 2.3 – –

1

 Iron (total) was detected in one of the 10 field blanks at a concentration of 20 μg/L; however, the SRL used for iron data from the USGS NWQL was applied 

to the iron data from the USGS Trace Metal Laboratory (TML) on the basis of comparison between the two datasets (see appendix for further discussion).

2

 Iron (II) is not measured if iron (total) is a non-detection.

3

 Result is a non-detection less than a raised MDL. The raised MDLs are: 0.5 μg/L for arsenic (total), 1 μg/L for arsenic (III), and 3 μg/L for iron (II).

4

 Conveyance from the TV-03 spring source to the point of use is an open channel.

Table 15. Results for analyses of species of inorganic arsenic and iron in samples collected for the Cascade Range and Modoc 

Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued

[Data in this table were analyzed at U.S. Geological Survey (USGS) Trace Metals Laboratory for the purpose of determining ratios of oxidized and reduced 

species of arsenic and iron. Information about the analytes given in table 4H. Absolute concentrations may be less accurate than those in table 10. GAMA well 

identification number: ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc 

Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study 

area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type, and benchmark level as of January 10, 2012. 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. Other abbreviations: MDL, method detection 

limit; na, not available; μg/L, micrograms per liter; na, not available; nc, not collected; –, not detected; ≤, less than or equal to; *, value above benchmark level]
Tables 95

Table 16. Results for analyses of stable isotope ratios, tritium activity, and carbon-14 abundance detected in samples collected for 

the Cascade Range and Modoc Plateau (CAMP) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, July through 

October 2010, California GAMA Priority Basin Project.

[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. 

Information about the analytes given in tables 4G and 4I. Samples from all 90 grid wells were analyzed for stable isotopes of hydrogen and oxygen in water 

and tritium activities. Samples from 87 grid wells were analyzed for stable isotopes of carbon in dissolved inorganic carbon and carbon-14 abundance. Stable 

isotope ratios 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. Tritium values less than the sample-specific critical level (ssLC) are reported as non–detections (–). GAMA well identification number: 

ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins 

study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary 

Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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. Other abbreviations: CSU, 1-sigma combined standard uncertainty; H, 

hydrogen; O, oxygen; C, carbon; pCi/L, picocuries per liter; ±, plus or minus; na, not available; nc, not collected]

GAMA well

identification

number

δ2H 

(per mil) 

(82082)

δ18O 

(per mil) 

(82085)

Tritium 

(pCi/L) 

(07000)

δ13C 

(per mil) 

(82081)

Carbon-14 

(percent modern) 

(49933)

Benchmark type na na MCL–CA na na

Benchmark level na na 20,000 na na

Result ± CSU ssLC

CAMP Sacramento Valley Eastside study area

CAMP–ES-01 –65.7 –9.81 6.50 ± 0.45 0.22 –22.43 106

CAMP–ES-02 –61.9 –9.26 6.80 ± 0.43 0.22 –22.04 111

CAMP–ES-03 –77.2 –10.72 0.50 ± 0.30 0.15 –18.47 78

CAMP–ES-04 –60.0 –8.54 5.00 ± 0.36 0.18 –17.25 87

CAMP–ES-05 –65.1 –9.69 1.20 ± 0.30 0.15 –21.46 91

CAMP–ES-06 –66.4 –10.05 1.50 ± 0.30 0.15 –20.27 96

CAMP–ES-07 –81.3 –11.32 3.40 ± 0.45 0.22 –18.82 93

CAMP–ES-08 –81.0 –11.54 2.70 ± 0.44 0.22 –19.24 93

CAMP–ES-09 –65.8 –9.34 1.10 ± 0.43 0.22 –19.29 85

CAMP–ES-10 –65.4 –9.34 0.50 ± 0.35 0.18 –19.26 88

CAMP–ES-11 –67.9 –9.88 4.60 ± 0.46 0.23 –21.16 100

CAMP–ES-12 –65.8 –9.97 6.10 ± 0.45 0.22 –22.29 114

CAMP–ES-13 –65.5 –9.68 8.90 ± 0.51 0.25 –21.05 114

CAMP–ES-14 –61.8 –9.00 0.40 ± 0.38 0.19 –16.58 94

CAMP–ES-15 –63.6 –9.15 2.80 ± 0.43 0.22 –16.16 96

CAMP Honey Lake Valley study area

CAMP–HL-01 –112 –14.51 – ± 0.41 0.41 –11.61 25

CAMP–HL-02 –103 –13.32 1.60 ± 0.45 0.45 –18.27 54

CAMP–HL-03 –112 –14.64 1.50 ± 0.41 0.41 –16.47 66

CAMP–HL-04 –108 –14.04 0.70 ± 0.35 0.32 –13.37 63

CAMP–HL-05 –103 –13.36 5.70 ± 0.44 0.22 –16.01 80

CAMP–HL-06 –99.1 –12.93 8.40 ± 0.47 0.24 –16.59 101

CAMP–HL-07 –106 –13.59 – ± 0.31 0.16 –12.90 33

CAMP–HL-08 –102 –13.32 0.40 ± 0.30 0.15 –14.85 55

CAMP–HL-09 –110 –13.78 – ± 0.30 0.15 –12.79 57

CAMP–HL-10 –108 –13.53 1.00 ± 0.30 0.15 –13.31 68

CAMP–HL-11 –105 –13.17 4.80 ± 0.32 0.16 –13.31 81

CAMP–HL-12 –108 –13.70 1.70 ± 0.30 0.15 –15.54 90

CAMP–HL-13 –109 –14.30 1.90 ± 0.33 0.16 –14.78 99

CAMP–HL-14 –112 –14.40 – ± 0.36 0.18 –14.13 50

CAMP–HL-15 –108 –13.31 1.40 ± 0.36 0.18 –11.81 84
96 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

GAMA well

identification

number

δ2H 

(per mil) 

(82082)

δ18O 

(per mil) 

(82085)

Tritium 

(pCi/L) 

(07000)

δ13C 

(per mil) 

(82081)

Carbon-14 

(percent modern) 

(49933)

Benchmark type na na MCL–CA na na

Benchmark level na na 20,000 na na

Result ± CSU ssLC

CAMP Cascade Range and Modoc Plateau Low Use Basins study area

CAMP–LU-01 –108 –13.72 – ± 0.31 0.31 –10.52 24

CAMP–LU-02 –108 –13.54 – ± 0.32 0.32 7.43 9

CAMP–LU-03 –110 –13.74 1.60 ± 0.35 0.32 –13.75 58

CAMP–LU-04 –106 –13.72 10.20 ± 0.51 0.35 –12.48 93

CAMP–LU-05 –111 –13.70 1.20 ± 0.32 0.32 –13.07 57

CAMP–LU-06 –109 –13.59 – ± 0.35 0.35 –11.71 32

CAMP–LU-07 –104 –13.72 3.00 ± 0.32 0.32 –16.69 98

CAMP–LU-08 –92.9 –13.21 13.10 ± 0.64 0.35 –19.01 110

CAMP–LU-09 –110 –13.72 – ± 0.32 0.32 –12.15 70

CAMP–LU-10 –59.3 –4.60 – ± 0.41 0.42 –9.43 82

CAMP–LU-11 –102 –13.15 2.20 ± 0.35 0.32 –15.06 88

CAMP–LU-12 –90.8 –12.80 10.60 ± 0.41 0.35 nc nc

CAMP–LU-13 –92.9 –11.39 6.30 ± 0.48 0.38 –16.43 91

CAMP–LU-14 –97.1 –13.48 7.50 ± 0.37 0.18 –16.51 83

CAMP–LU-15 –99.7 –13.62 7.90 ± 0.40 0.20 –17.72 96

CAMP Quaternary Volcanic Areas study area

CAMP–QV-01 –96.2 –13.49 9.10 ± 0.48 0.32 –18.77 111

CAMP–QV-02 –92.9 –13.17 8.70 ± 0.51 0.32 –18.64 112

CAMP–QV-03 –115 –14.58 – ± 0.32 0.32 –14.94 6

CAMP–QV-04 –77.8 –8.10 5.90 ± 0.54 0.45 –9.54 83

CAMP–QV-05 –91.6 –12.76 2.00 ± 0.45 0.42 nc nc

CAMP–QV-06 –113 –14.78 10.20 ± 0.48 0.31 –15.62 50

CAMP–QV-07 –89.7 –12.64 6.00 ± 0.46 0.23 –18.85 90

CAMP–QV-08 –99.8 –13.81 2.90 ± 0.35 0.18 –14.83 88

CAMP–QV-09 –102 –14.36 3.30 ± 0.30 0.15 –16.95 91

CAMP–QV-10 –80.4 –10.98 1.50 ± 0.34 0.17 –19.85 94

CAMP–QV-11 –78.4 –11.36 3.80 ± 0.42 0.21 –20.67 95

CAMP–QV-12 –77.6 –10.95 8.20 ± 0.42 0.21 –18.69 109

CAMP–QV-13 –93.5 –13.00 4.00 ± 0.34 0.17 –12.60 47

CAMP–QV-14 –99.2 –13.65 0.20 ± 0.30 0.15 –18.35 58

CAMP–QV-15 –88.0 –12.41 11.60 ± 0.53 0.26 –15.82 77

Table 16. Results for analyses of stable isotope ratios, tritium activity, and carbon-14 abundance detected in samples collected for 

the Cascade Range and Modoc Plateau (CAMP) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, July through 

October 2010, California GAMA Priority Basin Project.—Continued

[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. 

Information about the analytes given in tables 4G and 4I. Samples from all 90 grid wells were analyzed for stable isotopes of hydrogen and oxygen in water 

and tritium activities. Samples from 87 grid wells were analyzed for stable isotopes of carbon in dissolved inorganic carbon and carbon-14 abundance. Stable 

isotope ratios 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. Tritium values less than the sample-specific critical level (ssLC) are reported as non–detections (–). GAMA well identification number: 

ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins 

study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary 

Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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. Other abbreviations: CSU, 1-sigma combined standard uncertainty; H, 

hydrogen; O, oxygen; C, carbon; pCi/L, picocuries per liter; ±, plus or minus; na, not available; nc, not collected]
Tables 97

Table 16. Results for analyses of stable isotope ratios, tritium activity, and carbon-14 abundance detected in samples collected for 

the Cascade Range and Modoc Plateau (CAMP) Groundwater Ambient Monitoring and Assessment (GAMA) study unit, July through 

October 2010, California GAMA Priority Basin Project.—Continued

[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. 

Information about the analytes given in tables 4G and 4I. Samples from all 90 grid wells were analyzed for stable isotopes of hydrogen and oxygen in water 

and tritium activities. Samples from 87 grid wells were analyzed for stable isotopes of carbon in dissolved inorganic carbon and carbon-14 abundance. Stable 

isotope ratios 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. Tritium values less than the sample-specific critical level (ssLC) are reported as non–detections (–). GAMA well identification number: 

ES, Sacramento Valley Eastside study area grid well; HL, Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins 

study area grid well; QV, Quaternary Volcanic Areas study area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary 

Volcanic Areas study area grid well. Benchmark type and benchmark level as of January 10, 2012. 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. Other abbreviations: CSU, 1-sigma combined standard uncertainty; H, 

hydrogen; O, oxygen; C, carbon; pCi/L, picocuries per liter; ±, plus or minus; na, not available; nc, not collected]

GAMA well

identification

number

δ2H 

(per mil) 

(82082)

δ18O 

(per mil) 

(82085)

Tritium 

(pCi/L) 

(07000)

δ13C 

(per mil) 

(82081)

Carbon-14 

(percent modern) 

(49933)

Benchmark type na na MCL–CA na na

Benchmark level na na 20,000 na na

Result ± CSU ssLC

CAMP Shasta Valley and Mount Shasta Volcanic Area study area

CAMP–SH-01 –98.0 –12.56 9.80 ± 0.47 0.31 –13.52 82

CAMP–SH-02 –94.2 –12.10 2.80 ± 0.34 0.30 –12.68 59

CAMP–SH-03 –99.4 –12.86 8.50 ± 0.47 0.33 –13.15 99

CAMP–SH-04 –105 –14.42 0.40 ± 0.31 0.31 –14.09 48

CAMP–SH-05 –105 –14.56 2.40 ± 0.34 0.31 –12.56 48

CAMP–SH-06 –101 –14.15 4.80 ± 0.41 0.34 –14.76 71

CAMP–SH-07 –98.0 –13.70 8.10 ± 0.45 0.31 –19.40 109

CAMP–SH-08 –98.8 –13.62 3.60 ± 0.41 0.35 –14.71 67

CAMP–SH-09 –95.3 –12.46 6.80 ± 0.48 0.35 –14.57 96

CAMP–SH-10 –95.3 –12.50 6.40 ± 0.48 0.35 –11.06 74

CAMP–SH-11 –92.2 –12.05 8.40 ± 0.45 0.32 –11.15 92

CAMP–SH-12 –99.3 –12.67 5.40 ± 0.45 0.22 –14.93 92

CAMP–SH-13 –107 –14.11 5.60 ± 0.44 0.22 –9.55 47

CAMP–SH-14 –93.0 –13.16 11.40 ± 0.61 0.30 –20.14 100

CAMP–SH-15 –98.5 –12.69 6.00 ± 0.32 0.16 –15.60 98

CAMP Tertiary Volcanic Areas study area

CAMP–TV-01 –100 –12.32 45.7 ± 1.3 0.31 –14.40 42

CAMP–TV-02 –97.6 –13.11 3.50 ± 0.38 0.35 –13.41 87

CAMP–TV-03 1 –91.9 –12.79 5.40 ± 0.48 0.38 –12.99 55

CAMP–TV-04 –94.6 –13.49 0.50 ± 0.39 0.20 –13.48 71

CAMP–TV-05 –109 –14.23 0.10 ± 0.36 0.18 –14.46 77

CAMP–TV-06 –101 –14.01 6.80 ± 0.36 0.18 –16.62 79

CAMP–TV-07 –114 –15.26 – ± 0.30 0.15 –16.54 86

CAMP–TV-08 –115 –15.07 0.90 ± 0.36 0.18 –14.96 52

CAMP–TV-09 –100 –13.79 0.30 ± 0.32 0.16 –15.59 51

CAMP–TV-10 –97.3 –13.42 3.70 ± 0.40 0.20 –20.94 97

CAMP–TV-11 –80.0 –11.43 9.20 ± 0.30 0.15 –19.73 93

CAMP–TV-12 –79.3 –11.35 8.70 ± 0.45 0.22 nc nc

CAMP–TV-13 –78.9 –11.24 7.40 ± 0.39 0.20 –21.35 104

CAMP–TV-14 –75.0 –10.86 7.40 ± 0.50 0.25 –20.59 108

CAMP–TV-15 –93.8 –11.09 0.80 ± 0.43 0.22 –16.07 53

1

 Conveyance from the TV–03 spring source to the point of use is an open channel.
98 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table 17. Microbial indicator constituents detected in samples collected for the Cascade Range and Modoc Plateau (CAMP) study 

unit, July through October 2010, California GAMA Priority Basin Project.

[The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent 

or property. Samples from 83 grid wells were analyzed (samples were not collected at wells CAMP-HL-06, -LU-09, -LU-10, -LU-11, -QV-03, -QV-04, and 

TV-02). Information about the analytes given in table 4J. GAMA well identification number: ES, Sacramento Valley Eastside study area grid well; HL, 

Honey Lake Valley study area grid well; LU, Cascade Range and Modoc Plateau Low Use Basins study area grid well; QV, Quaternary Volcanic Areas study 

area grid well; SH, Shasta Valley and Mount Shasta Volcanic Area study area grid well; TV, Tertiary Volcanic Areas study area grid well. Benchmark type and 

benchmark level as of January 10, 2012. 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: –, not detected; D, detected]

GAMA well

identification

number

Escherichia coli

(E. coli) 

(99596)

Total coliform

(including fecal 

coliform and E. coli) 

(99595)

Benchmark type TT-US MCL-US

Benchmark level No fecal coliforms are allowed 5 percent of samples per month

CAMP Sacramento Valley Eastside study area (15 grid wells sampled)

CAMP-ES-15 – D

CAMP Honey Lake Valley study area (14 grid wells sampled)

CAMP-HL-01 – D

CAMP Cascade Range and Modoc Plateau Low Use Basins study area (12 grid wells sampled)

CAMP-LU-02 – D

CAMP-LU-12 – D

CAMP Quaternary Volcanic Areas study area (13 grid wells sampled)

CAMP-QV-09 – D

CAMP Shasta Valley and Mount Shasta Volcanic Area study area (15 grid wells sampled)

CAMP-SH-03 – D

CAMP-SH-12 – D

CAMP-SH-13 – D

CAMP Tertiary Volcanic Areas study area (14 grid wells sampled)

CAMP-TV-03 1 D D

1

 Conveyance from the TV-03 spring source to the point of use is an open channel.
Appendix 99

Appendix
100 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

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 

well 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 CAMP study unit, groundwater samples were 

collected, and QA/QC procedures were implemented using 

standard and modified USGS protocols from the USGS 

NAWQA Program (Koterba and others, 1995), the USGS 

National Field Manual (U.S. Geological Survey, variously 

dated), and protocols described by Shelton and others (2001) 

and Wright and others (2005). 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 to a distribution 

system. Sites were classified as springs if groundwater 

could discharge from the aquifer into the distribution 

system without a pump, and if the well was either drilled 

horizontally or had no drilled hole. A few springs had pumps 

to transport groundwater from the spring to a storage tank at a 

higher elevation. 

In most cases, wells were pumped continuously to purge 

at least three casing volumes of water from the well prior 

to sampling (Wilde and others, 1999). Drought conditions 

during the period of sampling for the CAMP study unit (July 

through October 2010) resulted in limitations on the amount 

of groundwater that could be pumped from some of the wells. 

In some cases, continuous pumping was limited to 2 hours, 

either because of limited space in storage tanks for the 

pumped water or because of drawdown of the water table. A 

minimum of one casing volume of groundwater was pumped 

from each well before sampling. The limitation on pumping 

did not allow sufficient time to complete the sampling of a 

few wells, and some constituent groups were not collected 

from these wells. 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 and upstream from 

a wellhead treatment system (if any). If a chlorinating system 

was attached to the well, the chlorinator was shut off when 

possible before the well or spring was purged and sampled in 

order to clear all chlorine out of the system. The absence of 

free chlorine was verified using Hach field kits. The mobile 

laboratory could not be parked within 50 feet of the sampling 

point at most of the sampling sites; therefore, all samples 

were collected outdoors by connecting a 1- to 3-foot length 

of Teflon® tubing to the sampling point (Lane and others, 

2003). All fittings and lengths of tubing were cleaned between 

samples (Wilde, 2004). 

For the field measurements, groundwater was pumped 

through a flow-through chamber 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 National Field Manual (Radtke 

and others, 2005; Wilde and Radtke, 2005; Lewis, 2006; 

Wilde, 2006; Wilde and others, 2006). The flow-through 

chamber was attached to the same sampling point used for 

sample collection. All sensors on the multi-probe meter were 

calibrated daily. Measured temperature, dissolved oxygen, pH, 

and specific conductance values were recorded at 5-minute 

intervals for approximately 30 minutes, and when these 

values remained stable for 20 minutes, samples for laboratory 

analyses then were collected. 

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. 

A few springs were not plumbed, and they discharged 

into pools from which the water was then pumped into the 

distribution system. For these springs, 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. Turbidity was measured in the mobile laboratory 

with a calibrated turbidity meter (Anderson, 2005). In all 

cases, turbidity was less than 0.5 nephelometric turbidity units 

(NTU), and the samples were collected unfiltered, but were 

marked as filtered for analysis. 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.

Field measurements and instrument calibrations were 

recorded by hand on field record sheets and electronically 

in the Personal Computer Field Form (PCFF) program. 

Analytical service requests also were managed by PCFF. 

Information from PCFF was uploaded directly into NWIS at 

the end of every week of sample collection. 

Prior to sample collection, polyethylene sample bottles 

were pre-rinsed two times using deionized water and then 

once with sample water before sample collection. Samples 

requiring acidification were acidified to a pH of between 2 

and 1 with the appropriate acids using ampoules of certified, 

traceable concentrated acids obtained from the NWQL.
Appendix 101

Temperature-sensitive samples were stored on ice prior 

to and during daily shipping to the various laboratories. The 

non-temperature-sensitive samples for tritium, stable isotopes 

of hydrogen and oxygen in water, and dissolved noble gases 

were shipped monthly. Temperature- or time-sensitive samples 

for VOCs, pesticides and pesticide degradates, perchlorate, 

trace elements, nutrients, major and minor ions, silica, TDS, 

laboratory alkalinity, radon-222, and gross alpha and gross 

beta radioactivity were shipped within 2 days of sample 

collection (samples were shipped daily whenever possible). 

Samples to be analyzed for species of arsenic and iron 

were shipped weekly. The temperature-sensitive samples 

for stable isotopes of carbon in dissolved inorganic carbon 

and carbon-14 abundance were stored on ice, archived in a 

laboratory refrigerator, and shipped after all of the alkalinity 

measurements were collected. Boron, strontium, and uranium 

isotope samples were stored at room temperature in the office 

until results from the trace element analyses for all 90 samples 

were received. A subset of samples were selected for isotope 

analyses on the basis of the trace element results. 

Detailed sampling protocols for individual analyses and 

groups of analytes are described in Koterba and others (1995), 

the USGS National Field Manual (Wilde and others, 1999, 

2004), and the references for analytical methods listed in 

table A1; only brief descriptions are given here. VOC samples 

were collected in three 40-mL sample vials that were purged 

with three vial volumes of groundwater before bottom filling 

to eliminate atmospheric contamination. Hydrochloric acid 

in a one-to-one (1:1) hydrochloric acid to water (HCl/H2O) 

solution was added as a preservative to the VOC samples. 

Each sample to be analyzed for perchlorate was collected in 

a 125-mL polystyrene bottle and then filtered in two or three 

20-mL aliquots of groundwater through a 0.20-μm pore-size 

Corning® syringe-tip disk filter into a sterilized 125-mL bottle. 

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 water. Samples for analysis of stable isotopes of 

hydrogen and oxygen in water were collected in a 60-mL clear 

glass bottle filled with unfiltered groundwater, sealed with a 

conical cap, and secured with electrical tape to prevent leakage 

and evaporation.

Pesticide and pesticide degradate samples were 

collected in 1-L baked amber glass bottles. Samples were 

filtered through a 0.7-μm nominal pore-size glass fiber filter 

during collection.

Groundwater samples for trace elements, major and 

minor ions, silica, and TDS analyses 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 

using either a 0.45-μm pore-size Whatman® vented capsule 

filter or a 0.45-μm pore-size PALL® unvented capsule filter 

that was pre-rinsed with 2 L of deionized water, then rinsed 

with 1 L of groundwater prior to sampling. The 250-mL 

filtered sample then was preserved with 7.5-normal (7.5-N) 

nitric acid. Samples to be analyzed for species of arsenic and 

iron were filtered into 250-mL polyethylene bottles that were 

covered with tape to prevent light exposure, and preserved 

with 6-N hydrochloric acid. Nutrient samples were collected 

by filtering groundwater into a 125-mL brown polyethylene 

bottle. Samples to be analyzed for strontium isotopes were 

filtered into 250-mL polyethylene bottles after bottles were 

rinsed with filtered groundwater and secured with electrical 

tape to prevent leakage and evaporation. Samples to be 

analyzed for uranium isotopes and gross alpha and gross beta 

particle activities were filtered into 1-L polyethylene bottles 

and acidified with nitric acid. Stable isotopes of carbon in 

dissolved inorganic carbon and carbon-14 abundance samples 

were filtered and bottom filled into 500-mL glass bottles that 

first were overfilled with three bottle volumes of groundwater. 

These samples had no headspace and were sealed with 

conical caps to avoid atmospheric contamination. Samples 

for laboratory or field alkalinity titrations were collected by 

filtering groundwater into a 500-mL polyethylene bottle.

For the collection 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 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 and shaken. The vial 

then was placed in an insulated cardboard tube to protect the 

sample during shipping. 

Dissolved noble gases were collected in 3⁄8-inch-diameter 

copper tubes using reinforced nylon tubing connected to the 

hose bib at the wellhead. Groundwater was flushed through the 

tubing to dislodge 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 also were collected at the wellhead using 

the IDEXX Colilert® test kit following standard methods 

(American Public Health Association, 1998). Prior to the 

collection of samples, the sampling port was sterilized 

using isopropyl alcohol, and then was flamed or let 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 Colilert® sterile sample bottle containing sodium 

thiosulfate (to neutralize chlorine when present) was filled 

directly from the sampling. 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 35oC ± 

0.5oC. 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) yellow equal to or greater than the 

comparator, then the presence of total coliform was detected; 
102 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

(3) yellow and fluorescence equal to or greater than the 

comparator, then the presence of E. coli was detected. Some 

samples were not analyzed because the incubator temperature 

sensors fluctuated outside of the required temperature range 

during the incubation time period. 

Field alkalinity was measured in the mobile laboratory 

at the well site. Alkalinity was measured on filtered samples 

by Gran’s titration method (Gran, 1952). Titration data 

were entered directly into PCFF, and the concentrations 

of bicarbonate (HCO3

–) and carbonate (CO32–) were 

automatically calculated from the titration data 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 CO32– also were calculated from 

the laboratory alkalinity and laboratory pH measurements. 

Nine laboratories performed chemical and microbial 

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. NWQL 

maintains National Environmental Laboratory Accreditation 

Program (NELAP) and other certifications (http://www.

nelac-institute.org/accred-labs.php). 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 that includes annual testing of all USGS 

field personnel for proficiency in making field water-quality 

measurements (http://bqs.usgs.gov/nfqa/). Results for analyses 

made at the NWQL or by laboratories contracted by the 

NWQL are uploaded directly into NWIS. Results of analyses 

made at other laboratories are compiled in a project database 

and uploaded from there into NWIS. Some laboratory QC data 

are stored in NWIS also.

Data Reporting

The following section gives details for the laboratory 

reporting conventions and the constituents that are determined 

by multiple methods or by multiple laboratories.

Reporting Limits

The USGS NWQL uses different conventions for 

reporting results for organic and inorganic constituents. For 

organic constituents (VOCs and pesticides), a laboratory 

reporting level (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 CAMP study unit (July 12 through 

October 14, 2010). The LRLs for some organic constituents 

changed on October 1, 2010; both values are reported in 

tables 4A–B, and the higher of the two values is reported with 

the groundwater-quality data in tables 6 and 7. Non-detections 

are reported as less than the LRL (<LRL).

Concentrations between the LRL and the LT-MDL are 

reported as estimated concentrations (coded by the letter “E” 

preceding the values in the tables and text). For informationrich methods, detections less than the LT-MDL have a 

high certainty of detection, but the precise concentration 

is uncertain. These values are also E-coded. Informationrich methods are those that utilize gas chromatography or 

high-performance liquid chromatography (HPLC) with 

mass spectrometry detection, such as those methods used to 

analyze VOCs and pesticides. Compounds are identified by 

the presence of characteristic fragmentation patterns in their 

mass spectra in addition to being quantified by measurement 

of peak areas at their associated chromatographic retention 

times. 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).

Prior to September 30, 2010, the USGS NWQL reported 

inorganic constituents (trace elements, nutrients, major and 

minor ions, and TDS) using the same reporting conventions 

as used for organic constituents: non-detections were reported 

as <LRL, and detections with concentrations between the 

LT-MDL and LRL were reported as E-coded values (methods 

used for inorganic constituents are not information-rich 

methods; thus, no detections with concentrations <LT-MDL 

were reported). The reporting conventions changed on 

October 1, 2010 (U.S. Geological Survey Office of Water 

Quality, 2010), and this report uses the new reporting 

conventions for samples collected both before and after 

October 1, 2010. For the new reporting conventions, nondetections of inorganic constituents are reported as <LT-MDL, 

and E-coding is not applied to any detections. As in the old 

reporting convention, methods used for inorganic constituents 

are not information-rich methods; thus, no detections with 
Appendix 103

concentrations <LT-MDL are reported. The LT-MDLs for 

some inorganic constituents changed on October 1, 2010; 

both values are reported in tables 4D–F, and the higher of the 

two values is reported with the groundwater-quality data in 

tables 9–11. Detections with concentrations between the lower 

and higher LT-MDLs are reported as non-detections relative to 

the higher LT-MDL.

Some constituents in this study are reported using 

minimum reporting levels (MRLs) or method uncertainties 

(MU). 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 be found. 

Results for most constituents are presented using the 

LRL, LT-MDL, MDL, MRL, or MU values provided by the 

analyzing laboratories. Results for some organic and inorganic 

constituents are presented using study reporting levels (SRLs) 

derived from assessment of data from QC samples associated 

with groundwater samples collected as part of the GAMA PBP 

(see the appendix section titled “Detections in Field Blanks 

and Application of SRLs”).

The methods used for analysis of radiochemical 

constituents (tritium, uranium isotopes, radon-222, and gross 

alpha and gross beta radioactivity) measure activities by 

using counting techniques (table A1). The reporting limits 

for 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 radiochemical 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.

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 (CSU). The CSU 

is reported at the 68-percent confidence level (1-sigma). The 

ssLC was not reported for some tritium results, and one-half of 

the CSU was used as an estimate. 

Notation

Stable isotopic compositions of oxygen, carbon, boron, 

and hydrogen are reported as relative isotope ratios in units of 

per mil using the standard delta notation (Coplen and others, 

2002):

1 1,000 per mil

where

is the atomic mass of the heavier isotope of

the element;

is the element (H for hydrogen, O for oxygen,

B for boron, C for carbon);

is the ratio o

i sample

reference

sample

R

E

R

i

E

R

 

δ = −×      

2 18 11 13

1 16

10 12

f the abundance of the heavier

isotope of the element ( H, O, B, C)

to the lighter isotope of the element ( H, O,

B, C) in the sample; and

is the ratio of the abundance of the heavie Rreference r 

isotope of the element to the lighter isotope 

of the element in the reference material.

(1)

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) 

(Coplen and others, 2002). The reference material for boron 

is the National Institute of Standards and Technology (NIST) 

reference material SRM 951 boric acid, which is assigned 

a δ 11B value of 0 per mil (Coplen and others, 2002). The 

reference material for carbon is Vienna Pee Dee Belemnite 

(VPDB), which is assigned a δ13C value of 0 per mil (Coplen 

and others, 2002). 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. The isotopic composition 

of strontium is reported as the ratio of the abundance of 

the heavier isotope to the abundance of the lighter isotope, 

87Sr/86Sr (for example, Faure, 1986).

Constituents on Multiple Analytical Schedules

Five constituents targeted in this study 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 field water-quality indicators—pH, specific 

conductance, and alkalinity—were measured in the field and at 

the NWQL. The field measurements are the preferred method 
104 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

for all three constituents; however, both measurements are 

reported. Field values are generally preferred because field 

conditions are considered more representative of groundwater 

conditions (Hem, 1985).

For arsenic and iron concentrations, the approved 

method, Schedule 1948, used by the NWQL (table 4E) is 

preferred over the research methods used by the USGS Trace 

Metal Laboratory (table 4H). The concentrations measured by 

the Trace Metal Laboratory are used only to calculate ratios of 

the abundance of the oxidized species to the abundance of the

reduced species for each element, As(V)

As(III)

 for arsenic and 

Fe(III)

Fe(II)

 for iron. For example,

Fe(III) Fe(T) - Fe(II)

Fe(II) Fe(II)

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).

= (2)

Quality-Control Methods and Results

The purpose of QC is to identify which data best 

represent environmental conditions and which data may 

have been affected by contamination or bias during sample 

collection, processing, storage, transportation, and (or) 

laboratory analysis. Four types of QC tests were used 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, and (4) surrogate compounds were added to 

samples analyzed for organic constituents to assess bias of 

laboratory analytical methods. 

Blanks

The primary purposes of collecting blanks are to evaluate 

the magnitude of potential contamination of samples with 

compounds of interest during sample collection, processing, 

transport, and (or) analysis and to identify and mitigate 

these sources of sample contamination. Results from blanks 

collected for the CAMP study unit and for previous GAMA 

study units were used to establish study reporting levels 

(SRLs) for some constituents detected in blanks. SRLs 

have higher concentrations than the reporting levels used 

by the laboratory. Detections reported by the laboratory 

with concentrations less than SRLs may have significant 

contamination bias. These data were flagged with an 

appropriate remark code (described in subsequent sections).

Blank Collection and Analysis

Field blanks were collected using blank water certified 

by the NWQL to contain less than the LRL, LT-MDL, 

MDL, or MRL of the analytes investigated in the study 

(http://wwwnwql.cr.usgs.gov/USGS/OBW/obw.html). 

Nitrogen‐purged, organic-free blank water was used for field 

blanks of organic constituents, and inorganic-free blank water 

was used for field blanks of other constituents. 

Field blanks were analyzed for VOCs, pesticides and 

pesticide degradates, perchlorate, trace elements, nutrients, 

major ions and TDS, species of arsenic and iron, and microbial 

indicators. Field blanks were not collected for uranium 

isotopes, gross alpha and gross beta particle activities, or 

radon because the laboratory determines a sample-specific 

critical level (ssLC) value for each sample. The ssLC is the 

minimum measured value that indicates a non-zero amount 

of the radionuclide in the sample. Field blanks were not 

collected for tritium and dissolved noble gases because 

these constituents are present 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 carbon, boron, hydrogen, oxygen, and strontium are 

an intrinsic property of any of these elements; therefore, the 

concept of a blank does not apply to these ratios.

To collect field blanks, blank water either was pumped or 

poured through the sampling equipment (fittings and tubing) 

used to collect groundwater samples, then processed and 

transported using the same protocols used for the groundwater 

samples. Four liters of blank water were pumped or poured 

through the sampling equipment before each field blank was 

collected.

Study Reporting Levels (SRLs)

SRLs for trace elements detected in field blanks collected 

in the first 20 GAMA PBP study units (May 2004 through 

January 2008) were defined by Olsen and others (2010) on the 

basis of statistical assessment of results from the field blanks. 

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, 

handled, transported, and analyzed. Detections of trace 

elements having concentrations less than the SRLs are marked 

with a ≤ symbol preceding the reported value in tables 10 and 

15 to indicate that the true value may be less than or equal 

to the reported value (including the possibility of being a 

non-detection).

SRLs for VOCs detected in field blanks collected for the 

first 32 GAMA PBP study units (May 2004 through September 

2010) were defined by Fram and others (2012) on the basis 

of assessment of results from field blanks, source-solution 

blanks, laboratory instrument blanks, and groundwater 

samples. Detections of VOCs having concentrations less than 

the SRLs are reported as non-detections in table 6.
Appendix 105

SRLs for other classes of constituents detected in field 

blanks collected for the CAMP study unit were defined as 

equal to the highest concentration measured in the field blanks. 

In addition, the highest concentration measured in field blanks 

was used as the SRL for some trace elements that were not 

assigned an SRL by Olsen and others (2010).

Detections in Field Blanks and Application of SRLs

Table A3 presents a summary of detections in the field 

blanks and the SRLs applied for the CAMP study unit. Field 

blanks were collected at approximately 10 percent of the sites 

sampled in the CAMP study unit; not all analyte classes were 

tested at every well.

Of the nine VOCs with SRLs, five were detected 

in field blanks or groundwater samples from the CAMP 

study unit. 1,2,4-Trimethylbenzene was detected in 3 of 

10 field blanks at concentrations ranging from 0.028 μg/L to 

0.079 μg/L (table A3), and in 55 of 90 groundwater samples at 

concentrations ranging from E0.02 μg/L to 0.50 μg/L (median 

0.06 μg/L). All detections had concentrations less than the 

SRL of 0.56 μg/L. All detections in groundwater samples were 

reclassified as non-detections. For the GAMA PBP, detections 

of 1,2,4-trimethylbenzene in blanks and groundwater samples 

are correlated with the presence of equipment in field vehicles 

used for collecting radon samples (Fram and others, 2012). 

The vials used to collect radon samples contain a scintillation 

cocktail made of mineral oil and 1,2,4-trimethylbenzene. 

Samples for radon analysis were collected at all sites in the 

CAMP study unit.

Toluene was detected in two groundwater samples at 

concentrations of E0.02 μg/L and 0.03 μg/L and was not 

detected in field blanks. Both detections had concentrations 

less than the SRL of 0.69 μg/L and were reclassified as 

non-detections. The source of the toluene contamination 

is uncertain. 

Acetone and tetrahydrofuran each were detected in 

one groundwater sample at concentrations of E0.6 μg/L and 

3 μg/L, respectively. Neither was detected in field blanks 

(table A3). Contamination of groundwater samples and field 

blanks by acetone, tetrahydrofuran, and (or) 2-butanone 

is associated with presence of PVC-cement at sample 

collection sites (some wells are plumbed with PVC piping) 

or with contamination of sample collection equipment 

with the methanol used for cleaning equipment (Fram and 

others, 2012). Field blanks with contamination from either 

of these two sources were not considered representative 

of groundwater conditions; therefore, no quality-control 

assessment could be made for these three solvents, and no 

concentration threshold could be established for the SRL. 

The SRL consists of reclassifying detections of these three 

solvents in groundwater samples as “not analyzed.” This is 

implemented in the USGS NWIS database by setting the data 

quality indicator code to “reviewed and rejected.”

Carbon disulfide was detected in 4 of 10 field blanks 

at concentrations ranging from E0.02 μg/L to 0.09 μg/L 

(table A3), and in 3 of 90 groundwater samples at 

concentrations ranging from 0.05 μg/L to E0.31 μg/L (table 5). 

All of the detections of carbon disulfide in groundwater 

samples have concentrations greater than the SRL of 

0.04 μg/L, therefore, no data were flagged. Two of the field 

blanks had detections with concentrations greater than the 

SRL and greater than the lowest concentration detected in 

groundwater samples (table A3). If the highest concentration 

measured in CAMP field blanks had been used as the SRL, the 

detection of carbon disulfide in groundwater sample QV-04 

would have been flagged with a “≤” and considered a nondetection. However, the detection of carbon disulfide in QV-04 

(0.05 μg/L) was confirmed by detection of carbon disulfide in 

the replicate sample collected at the same site (0.06 μg/L), and 

the oxidation-reduction state of QV-04 was consistent with 

the presence of naturally occurring carbon disulfide. Carbon 

disulfide forms naturally under sulfate-reducing conditions, 

and hydrogen sulfide odor was noted during sample collection 

(table 5). The likely source of carbon disulfide contamination 

is the gloves worn by field and laboratory personnel 

(Worthington and others, 2007). 

Perchlorate was detected in 3 of 10 field blanks collected 

for the CAMP study unit (table A3). The need for an SRL 

was evaluated using the entire population of field and 

source solution blanks collected in GAMA study units and 

analyzed by Weck Laboratory. Between August 2007 and 

November 2011, 88 field blanks and 58 source-solution blanks 

were analyzed for perchlorate. The method used by Olsen 

and others (2010) for determining SRLs for trace elements 

was applied to this population of field blanks to determine 

an SRL for perchlorate. The 90 percent confidence limit 

for the 90th percentile of 88 field blanks corresponds to the 

84th-ranked field blank. Because only 4 of the 88 field blanks 

had detections of perchlorate, the 84th-ranked field blank had 

a result of non-detection for perchlorate. Therefore, no SRL 

is defined for perchlorate. The reason that three of the four 

detections of perchlorate in field blanks occurred during the 

same time that samples were being collected for the CAMP 

study unit is still under investigation.

Ten field blanks were collected for analysis of trace 

elements. Six trace elements were detected in at least one 

field blank: cobalt, copper, iron, lead, manganese, and zinc 

(table A3). The detections of copper, iron, and zinc were at 

concentrations less than the SRL assigned by Olsen and others 

(2010). SRLs for cobalt (0.38 μg/L), lead (1.04 μg/L), and 

manganese (0.7 μg/L) were established on the basis of the 

highest detected concentration in the field blanks. Measured 

concentrations that were less than the SRLs were flagged with 

a “≤” symbol (table 10). There were no other trace elements 

detected in any of the field blanks in the CAMP study unit. 

GAMA SRLs from Olsen and others (2010) were used for 

barium, chromium, copper, iron, nickel, tungsten, and zinc. 
106 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Ten field blanks were collected for analysis of the species 

of arsenic and iron. Iron (total) was detected in one field blank 

at a concentration of 20 μg/L. However, an SRL was not 

defined for iron (total) on the basis of this field blank because 

comparison between results for iron analyzed by the USGS 

Trace Metal Laboratory (TML) (table 15) and iron analyzed 

by the USGS NWQL (table 10) indicated that the USGS TML 

samples were unlikely to have experienced greater amounts of 

contamination than the USGS NWQL samples. 

The results from the two laboratories were evaluated 

using methods used to evaluate replicates. The reporting limits 

for iron were 2 μg/L (MRL) at the USGS TML and 3 μg/L 

(LT-MDL) at the USGS NWQL. Of the 89 groundwater 

samples analyzed by both laboratories, 41 samples had 

reported concentrations of ≥3 μg/L from one or both 

laboratories and were therefore used in the evaluation. The 

Wilcoxon ranked-pairs test indicated that the difference 

between the two datasets was significant (p=0.49; the 

null hypothesis for the test is that the median of the paired 

differences between the two datasets is zero, thus a p-value 

greater than α = 0.05 indicates that the paired datasets are 

significantly different). Concentrations reported by the 

USGS TML were significantly lower than those reported by 

the USGS NWQL for the set of 41 data pairs. Twenty-eight 

samples had concentrations of iron less 20 μg/L (the 

concentration detected in the field blank). Of these 28 samples, 

21 had lower concentrations reported by the USGS TML than 

by the USGS NWQL. These results suggest that the USGS 

TML samples did not have greater amounts of contamination; 

thus, application of an SRL with a higher concentration than 

that applied to the USGS NWQL data may not be warranted.

The hypothesized source of contamination by iron is the 

metal fittings used in sample collection equipment (Olsen 

and others, 2010). This source of contamination would affect 

samples sent to both the USGS NWQL and the USGS TML. 

Therefore, the SRL that was applied to the USGS NWQL iron 

data (table 10) was also applied to the USGS TML iron data. 

Measured concentrations less than the SRL of 6 μg/L were 

flagged with a “≤” symbol (table 15). The data from the USGS 

TML were used to calculate ratios of oxidized to reduced 

species, not for reporting absolute concentrations.

Constituents were not detected in the field blanks for the 

following analyte groups: pesticides and pesticide degradates 

(9 field blanks); nutrients (10 field blanks); major ions and 

TDS (10 field blanks); and the microbiological indicators 

E. coli and total coliform (6 field blanks).

Replicates

Sequential replicate samples 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. 

Assessment of Replicate Samples

Two methods for measuring variability were needed to 

adequately assess precision over the broad range of measured 

concentrations of most constituents. The variability between 

measured concentrations in the pairs of sequential replicate 

samples was represented by the 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 which 

variability is assessed with SD and concentrations for which 

variability is assessed with RSD was defined as five times the 

reporting level (RL) for each constituent. The RL may be an 

LRL, LT-MDL, SRL, MDL, or MRL for each constituent. 

Replicate pairs of analyses of all constituents except for 

radiochemical constituents were evaluated as follows: 

• If both values were reported as detections, the SD 

was calculated if the mean concentration was <5 RL

for the constituent, or the RSD was calculated if the 

mean concentration was ≥5 RL for the constituent. 

Acceptable precision is defined as an SD of less 

than 1⁄2 RL or an RSD of less than 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 less than 

the RL, then a value of zero was substituted for the 

non-detection and the SD was calculated. Substituting 

zero for the non-detection yielded the maximum 

estimate of variability for the replicate pair. 

• If one value for a sample pair was reported as a nondetection and the other value was reported as a ≤-coded 

value (less than or equal to the SRL), or if both values 

were reported as ≤-coded values (less than or equal to 

the SRL), the SD was not calculated because the values 

may be analytically identical. The ≤-code indicates that 

the value is a maximum potential concentration, and 

that concentration may be low enough to be reported as 

a non-detection. 

• If one value was reported as a non-detection 

and the other value was reported as a detection 

greater than the RL, the variability for the pair was 

considered unacceptable.

Replicate pairs of analyses of radiochemical constituents 

were evaluated using the following equation (McCurdy and 

others, 2008):
Appendix 107

( )

1 2

2 2

1 2

1

1 2

2 and are the results for the two samples in

the replicate pair, and

 and are the combined standard uncertainties

associated wit

where

is the t

h the resu

est statisti

.

,

lts

c

CSU CSU

R R

z

CSU CSU

z

R R

− =

+

(3)

Values of z < 1.65 correspond to significant levels (p) 

<α=0.05, and thus indicate replicate pairs with acceptable 

precision. Replicate pairs with values that are statistically 

indistinguishable at a confidence level (α) of α=0.05 are 

defined as acceptable.

If results from replicate sample pairs indicate that 

precision is unacceptable for a constituent and no specific 

reason can be identified, 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 slightly less 

than that benchmark. Similarly, if measured concentrations 

are slightly less than a water-quality benchmark, then actual 

concentrations could be slightly greater than a benchmark. 

Also, 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. 

Variability in Replicate Samples

Tables A4A–C summarize the results of replicate 

analyses for constituents detected in groundwater samples 

collected in the CAMP study unit. Replicate analyses were 

made on approximately 10 percent of the samples collected. 

Of the 2,017 replicate pairs of constituents analyzed, 

811 were for constituents detected in at least one groundwater 

sample. Of these 811 pairs, 14 pairs [aluminum (3 pairs), 

cadmium, silver, thallium, nitrite (as nitrogen), total nitrogen, 

bromide, iron (II), uranium-238, radon-222, gross alpha 

particle activity (72-hour count), and gross beta particle 

activity (30-day count)] were outside the limits for acceptable 

precision. Of these 14 pairs, 9 were for a replicate pair 

containing a non-detection and a low-level detection. Results 

for replicate analyses for constituents that were not detected in 

groundwater samples are not reported in tables A4A–C. 

Ten replicate pairs of samples were analyzed for the 

85 VOCs, and all pairs were composed of two values reported 

as non-detections with the exception of one replicate pair 

of carbon disulfide and one replicate pair of chloroform 

(table A4A). These replicate pairs both yielded two values 

reported as detections, and both resulted in SDs within 

acceptable precision. 

Ten replicate pairs of samples were analyzed for the 

63 pesticide and pesticide degradate compounds, and all pairs 

were composed of two values reported as non-detections with 

the exception of two replicate pairs of deethylatrazine and 

one replicate pair of hexazinone (table A4A). These replicate 

pairs both yielded two values reported as detections, and both 

resulted in SDs within acceptable precision.

Ten replicate pairs of samples were analyzed for the 

perchlorate, and seven pairs were composed of two values 

reported as non-detections (table A4A). The three replicate 

pairs that yielded two values reported as detections all resulted 

in SDs within acceptable precision. 

Ten replicate pairs of samples were analyzed for the 

24 trace elements, and 116 of the 240 total pairs were 

composed of either two values reported as non-detections, 

a value reported as a non-detection and a value reported as 

≤SRL, or two values reported as ≤SRL. Of the remaining 

124 pairs of samples with at least one value reported as a 

detection, the SD value was greater than half of the LT-MDL 

for six pairs (aluminum, 3 pairs, cadmium, silver, and 

thallium), and the RSD value was greater than 10 percent for 

one pair (zinc) (table A4B).

Ten replicate pairs of samples analyzed for nutrients, 

major ions, TDS, and isotope tracers resulted in SDs within 

acceptable precision with the following exceptions: nitrite 

(1 pair), total nitrogen (1 pair), bromide (1 pair), and TDS 

(2 pairs). Ten replicate pairs of samples analyzed for species 

of arsenic and iron resulted in SD or RSD values within 

acceptable precision, with the exception of one one replicate 

pair for iron (III). 

Eight replicate pairs for tritium were analyzed for 

variability, and all pairs yielded statistically similar results 

(p≤0.05); therefore, they were considered acceptable 

(table A4C). 

Two replicate pairs for uranium isotopes (uranium-234, 

uranium-235, and uranium-238) were analyzed for variability 

(table A4C). One replicate pair for uranium-238 consisting of 

a non-detection and a detection was statistically unacceptable; 

the p-value for the normalized absolute difference is less than 

the significance level of α equal to 0.05 (equivalent to the test 

statistic z>1.65) (table A4C).

Ten replicate pair samples of radon-222 and gross alpha 

and gross beta particle activities were analyzed for variability 

(table A4C). One replicate pair out of 10 for radon-222, gross 

alpha particle activity (72-hour count), and gross beta particle 

activity (30-day count) was considered unacceptable (p>0.05) 

(table A4C).
108 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Six replicate pair samples of microbial indicators (E. coli

and total coliform) were analyzed for variability (table A4D). 

E. coli was not detected in any of these samples. Two of the 

six replicate pairs yielded a detection and a non-detection for 

the presence of total coliform (table A4D). Total coliform was 

not detected in the other four replicate pairs. The detection 

of the presence of microbial indicators must be verified with 

re-testing resulting in 5 percent of samples testing positive per 

month; one detection is not an violation of the MCL-US.

Environmental detections were not modified on the basis 

of the replicate analyses.

Matrix Spikes

The addition of a known concentration of a constituent 

(spike) to a replicate environmental sample enables the 

analyzing laboratory to determine the effect of the matrix, 

in this case groundwater, on the analytical technique used 

to measure the constituent. The known compounds added 

in matrix spikes are the same as those being analyzed in the 

method. This enables an analysis of matrix interferences on a 

compound-by-compound basis. For this study, matrix spikes 

were added by the laboratory performing the analysis. Low 

matrix-spike recovery may indicate that the compound might 

not be detected in some samples if it was present at very low 

concentrations. Low and high matrix-spike recoveries may be 

a potential concern if the concentration of a compound in a 

groundwater sample is close to the health-based benchmark; a 

low recovery could result in a falsely measured concentration 

less than the health-based benchmark, whereas a high recovery 

could result in a falsely measured concentration greater than 

the health-based benchmark.

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 (with a footnote 

in table 4B) as having unacceptable recoveries. For many 

constituents, an acceptable range of 70 to 130 percent for 

median matrix-spike recovery was more restrictive than the 

acceptable control limits for laboratory-set spike recoveries. 

Laboratory-set spikes are aliquots of laboratory blank water 

to which the same spike solution used for the matrix-spikes 

has been added. One set spike is analyzed with each set of 

samples. Acceptable control limits for set spikes are defined 

relative to the long-term variability in recovery. For example, 

for many NWQL schedules, acceptable set spike recovery is 

within ± 3 F-pseudosigma of the median recovery for at least 

30 set spikes (Connor and others, 1998). The F-pseudosigma 

is calculated by dividing the fourth-spread (analogous 

to interquartile range) by 1.349; therefore, the smaller 

the F-pseudosigma, the more precise the determinations 

(Hoaglin, 1983). 

 Matrix-spike tests were performed for VOCs and 

pesticides and pesticide degradates because the analytical 

methods for these constituents may be susceptible to 

matrix interferences. 

Matrix-Spike Recoveries

Tables A5A–C present a summary of matrix-spike 

recoveries for the CAMP study unit. Replicate samples for 

spike additions were collected at approximately 10 percent of 

the wells sampled, and not all analyte classes were tested at 

every well. 

Nine groundwater samples were spiked with VOCs 

to calculate matrix-spike recoveries (table A5A). Median 

matrix-spike recoveries for all 85 VOC spike compounds were 

between 70 and 130 percent. Six VOC spike compounds had 

one matrix-spike recovery greater than 130 percent. Of these 

VOC spike compounds, PCE was detected in groundwater 

samples (tables 4A, 6, and A5A). Four VOC spike compounds 

had one matrix-spike recovery less than 70 percent. Of these 

VOC spike compounds, carbon disulfide was detected in 

groundwater samples (tables 4A, 6, and A5A). Low recoveries 

may indicate that the compound might be present at very low 

concentrations but not detected in some samples.

Nine groundwater samples were spiked with pesticide 

and pesticide degradate compounds to calculate matrix-spike 

recoveries (table A5B). Median matrix-spike recoveries for 40 

of the 63 spike compounds were between 70 and 130 percent. 

At least one matrix-spike recovery for 26 pesticide and 

pesticide degradate spike compounds was less than 70 percent. 

Of these pesticide and pesticide degradate spike compounds, 

only hexazinone was detected in a groundwater sample 

(tables 4B, 7, and A5B). At least one matrix-spike recovery 

for sixteen pesticide and pesticide degradate spike compounds 

was greater than 130 percent, and four of these were detected 

in groundwater samples (carbaryl, deethylatrazine, metalaxyl, 

and tebuthiuron) (tables 4B, 7, and A5B).

Environmental detections were not modified on the basis 

of the matrix-spike recovery analysis. 

Surrogates

Surrogate compounds are added to environmental 

samples in the laboratory prior to analysis to evaluate the 

recovery of similar constituents. Surrogate compounds 

were added in the laboratory to all groundwater and QC 

samples that were analyzed for VOCs and pesticides and 

pesticide degradates by the NWQL. Surrogates are used to 

identify general problems that may arise during laboratory 

sample analysis that could affect the analysis results for all 

compounds in that sample. Potential problems include matrix 

interferences (such as high levels of dissolved organic carbon) 

that produce a positive bias or incomplete laboratory recovery 

(possibly because of improper maintenance and calibration of 

analytical equipment) that produces a 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).
Appendix 109

Surrogate Compound Recoveries

Table A6 lists the surrogate, the analytical schedule on 

which it was applied, the number of analyses for blank and 

environmental samples, the number of surrogate recoveries 

less than 70 percent, and the number of surrogate recoveries 

greater than 130 percent for the blank and environmental 

samples. Blank and environmental samples were considered 

separately to assess whether the matrices present in 

groundwater samples affect surrogate recoveries. 

In the CAMP study unit, most surrogate recoveries for the 

blank and environmental samples were within the acceptable 

range of 70 to 130 percent. In total, 93 percent of the blank 

and 91 percent of the environmental sample surrogate 

recoveries for VOC analyses were within the acceptable range 

(table A6). In addition, 94 percent of the blank and 88 percent 

of the environmental sample surrogate recoveries for pesticide 

and pesticide degradate analyses were within the acceptable 

range (table A6). There were no significant differences 

between VOC and pesticide and pesticide degradate surrogate 

recoveries in blank and environmental samples (Wilcoxon 

rank sum test, p < 0.05). Environmental detections were not 

modified on the basis of the surrogate recovery analysis. 

Other Quality-Control Results

Three other laboratory quality-control issues arose 

during the analysis of samples collected for CAMP: (1) the 

effect of holding-time violations on the results of radioactive 

constituent data, (2) the effect of failure to maintain cold 

sample temperatures during shipping of samples to the 

laboratory, and (3) the effect of internal laboratory QC tests 

indicating bias on the results of trace element data. 

Holding-Time Violations for Radioactive Constituents

Holding time refers to the time in calendar days from 

sample collection to the analysis of the sample. A holding-time 

violation is when a sample is analyzed past the given holding 

time for a particular analysis. The remote sampling areas 

within the CAMP study unit did not allow for immediate 

shipment of a few samples for the analysis of radon and gross 

alpha and gross beta particle activities. This resulted in the 

later arrival times at the laboratory, and thus the analysis was 

completed after the holding time. This may be important 

because a delay in the analysis at the laboratory may result in 

different measured activities than what may have been present 

in the groundwater. 

The gross alpha or gross beta particle activity reported 

result is the amount measured in the sample at the time of 

analysis. Radioactive decay occurs between the time of sample 

collection and measurement, and therefore gross alpha and 

gross beta particle activities change with time. For 11 samples, 

the gross alpha and (or) gross beta particle activity (72-hour 

count) analyses were made after expiration of the holding 

time; for one sample, the gross alpha and gross beta particle 

activity (30-day count) analyses were made after expiration of 

the holding time (table 14). 

The dominant sources of beta particles in most 

groundwater samples are radioactive decay of potassium-40 

and radium-228 present in the sample at the time of collection 

and radioactive decay of beta-particle emitting progeny 

of uranium-238 that formed from radioactive decay of 

uranium-238 present in the sample at the time of collection 

(Welch and others, 1995). These progeny have relatively short 

half-lives, thus, in samples with elevated uranium contents, 

gross beta particle activity would likely increase as sample 

holding time increased. Potassium-40 and radium-228 have 

relatively long half-lives, thus, gross beta particle activity 

due to decay of these species does not decrease much over 

timescales relevant to this project. Of the samples with gross 

beta particle activity (72-hour count) analyses made after 

expiration of the holding time, one sample had high uranium 

abundance (CAMP-HL-11, tables 12 and 14). The gross beta 

particle activity measured in the sample was 12 pCi/L, which 

is less than 1⁄4 of the benchmark value of 50 pCi/L. GAMA 

PBP assessments of the status of groundwater quality are 

based on proportions of the primary aquifer system having 

groundwater with activities or concentrations of constituents 

that are high, moderate, or low relative to the value of the 

benchmark. For inorganic constituents, the boundary between 

moderate and low is defined as 1⁄2 of the benchmark value. 

Thus, the delayed analysis times will not affect results of the 

assessment of status of groundwater quality in the CAMP 

study unit. 

The dominant sources of alpha particles in most 

groundwater samples are radioactive decay of alpha-particle 

emitting isotopes of uranium, radium, and radon present in the 

sample at the time of collection (note that radon is removed 

from the sample during sample preparation), and radioactive 

decay of alpha-particle emitting progeny of species present 

in the sample at the time of sample collection. Gross alpha 

particle activity commonly decreases during the first 3 weeks 

after sample collection due to decay of radium-224 and its 

alpha-particle emitting progeny, all of which have relatively 

short half-lives (Arndt, 2010). For samples collected by 

the GAMA PBP, gross alpha particle activity generally is 

well-correlated with uranium activity (for example, Fram 

and Belitz, 2012); thus, the presence of elevated uranium 

may be a proxy for elevated gross alpha particle activity. 

Of the four samples for which gross alpha particle activity 

measurements were made after expiration of the holding 

time, two had uranium concentrations less than 0.30 μg/L 

(CAMP-LU-12 and -TV-03), thus the reported gross alpha 

particle activities (1.72 pCi/L and 1.36 pCi/L, respectively) 

likely are not far from the values had the measurements been 

made on time. Two samples had uranium concentrations of 

approximately 5 μg/L (CAMP-HL-15 and -SH-12), suggesting 
110 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

that the reported gross alpha particle activities (10 pCi/L 

and 3.0 pCi/L, respectively) may be noticeably lower than 

they would have been had the measurements been made 

on time. The benchmark for gross alpha particle activity 

is 15 pCi/L (MCL-US). For CAMP-HL-15, it is possible 

that the delayed analysis resulted in decreasing the gross 

alpha particle activity from a high value to a moderate value 

relative to the benchmark. This would affect the results of the 

status assessment.

The radon-222 reported result is corrected back to the 

time of collection. Late analysis results in a higher ssLC and a 

higher CSU. The higher CSU means the result is less precise; 

however, it is not necessary to qualify the data because the 

CSU is reported with the data. If radon was very low in the 

sample, then late analysis might result in an ssLC higher than 

the measured value, resulting in a reported non-detection. The 

same 12 groundwater samples that were analyzed past the 

holding time for gross alpha and gross beta particle activities 

were analyzed past the holding time for radon-222. Holdingtime violations did not affect whether or not the reported 

results were above or below the benchmark. The only situation 

where late analysis would affect data interpretation is for 

samples with an activity close to the benchmark—the lower 

precision of the analysis (bigger CSU) may cause a sample 

to be counted as above benchmark when it is really below, 

or to be counted as below when it is really above. None of 

the CAMP late samples have radon activities close enough to 

benchmark (or 1⁄2 benchmark) for this to be an issue. 

Temperature Violations During Shipping of Samples

Samples collected for analysis of VOCs, pesticides, 

nutrients, trace elements, and major ions are shipped to the 

USGS NWQL in coolers packed with ice. Samples collected 

at the following eight sites were received after all of the ice 

had melted and the samples warmed to room temperature: 

CAMP-HL-05, -06, -07, and -08; CAMP-QV-07 and -08; and 

CAMP-TV-04 and -05. Quality-control samples collected at 

sites CAMP-HL-05 and CAMP-QV-07 were included in the 

same shipment. The question is whether or not the failure to 

keep the samples chilled affected the quality of the resulting 

data. Cool temperatures commonly are used as a means of 

sample preservation because they may decrease biotic and (or) 

abiotic degradation of some constituents and may slow the rate 

of sample degassing. 

The trace elements and most of the major ions do 

not undergo changes that alter their total concentrations, 

thus, results for those constituents were not affected by the 

warm temperatures. Comparisons of field and laboratory 

measurements of pH and alkalinity suggest that the warm 

samples did not experience different amounts of degassing 

of carbon dioxide than the rest of the samples: laboratory pH 

values generally were higher than field pH values when field 

pH values were less than 8.0, and the offsets between field and 

laboratory pH values in the warm samples were similar to the 

offsets for other samples of the same field pH.

Conversion among the nitrogen species ammonia, 

nitrite, and nitrate is biologically mediated. However, the 

primary means of preservation of nutrient samples is filtration 

because it removes the most of the bacteria. The nitrogen 

species measured in the eight samples are consistent with 

the dissolved oxygen (DO) measurements made at the time 

of sample collection, suggesting that interconversion was 

negligible: samples with DO > 1 mg/L have nitrate (the 

most oxidized of the three nitrogen species), and samples 

with DO < 1 mg/L have ammonia (the most reduced of the 

three nitrogen species) and no nitrate. The primary means of 

preservation for the pesticides also is filtration.

The warm temperatures were unlikely to have adversely 

affected the VOCs because the primary means of sample 

preservation is acidification. Maskarinec and others (1990) 

measured degradation rates of VOCs as a function of sample 

acidification and temperature and found that acidification 

effectively prevented degradation. Even in unacidified 

samples, they found that for most VOCs, the amount of 

degradation during the first 10 days was essentially the 

same in chilled and unchilled samples. The few VOCs that 

showed differences in degradation rates with temperature 

in unacidified samples were all VOCs that have GAMA 

SRLs that result in censoring of all or nearly all of the data, 

or are rarely detected by the GAMA PBP, occurring only in 

groundwater that has detections of many other related VOCs.

Laboratory Bias in Trace Element Analyses

Laboratory bias as indicated from internal laboratory QC 

tests is another issue that must be investigated to determine 

whether or not there is any effect on the data. The BQS 

operates an independent, external quality-assurance project 

called the Inorganic Blind Sample Project (IBSP) to monitor 

and evaluate the quality of results for analyses of trace 

elements, nutrients, and major ions by the NWQL. The IBSP 

submits standard reference samples consisting of natural 

matrix water samples spiked with reagent chemicals to contain 

known concentrations of the inorganic constituents (Farrar 

and Long, 1997). The IBSP samples are disguised as regular 

environmental samples for submission to the NWQL. The 

BQS uses results from the IBSP samples to evaluate potential 

bias, positive or negative, in the results reported by the 

NWQL on a continuous basis. The BQS IBSP data are readily 

available on the BQS website, and the BQS issues monthly 

summaries of the results, reporting the amount of bias (if any) 

observed in the results (http://bqs.usgs.gov/ibsp/).

The BQS monthly summaries were examined for 

July 2010 through November 2010, the period during which 

samples were analyzed for the CAMP study unit. The BQS 

reported that two inorganic constituents showed evidence 

of bias during this period: 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 for 

the data collected for the CAMP study unit. 
Appendix 111

The IBSP samples for boron had concentrations ranging 

from 16 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 relative percent 

difference between the measured and expected concentrations 

was –10 percent (standard deviation = 8 percent). The NL-CA 

for boron is 1,000 μg/L, a concentration much higher than 

the maximum concentration in the IBSP samples. A negative 

bias of 10 percent, or 3 μg/L, for groundwater samples with 

measured concentrations of less than 45 μg/L does not affect 

assessment of whether groundwater samples in the CAMP 

study unit have boron concentrations greater than or less than 

the NL-CA concentration or greater than or less than 1⁄2 of the 

NL-CA concentration. Moreover, 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 

relative percent difference 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 ISBP samples would be relevant for assessment of 

whether groundwater samples have cadmium concentrations 

greater than or less than the MCL-US concentration or greater 

than or less than 1⁄2 of the MCL-US concentration. However, 

the maximum concentration of cadmium in samples from the 

CAMP study unit was 0.12 μg/L (table 10); thus, a potential 

positive bias of 0.06 μg/L, or 8 percent, would not result in a 

measured concentration above either threshold when the true 

concentration would have been below the threshold.
112 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program Table A1. Analytical methods used for the determination of organic and inorganic constituents by the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) and additional contract laboratories. [Laboratory entity codes in the USGS National Water Information System (NWIS) for laboratories other than the NWQL are given in parentheses after the laboratory names. Abbreviation: VOC, volatile organic compound; USEPA, U.S. Environmental Protection Agency] Analyte Analytical Method Laboratory and analytical schedule Citation(s) Water-quality indicators Field water-quality indicators Calibrated field meters and test kits USGS field measurement U.S. Geological Survey, variously dated Organic constituents VOCs Purge and trap capillary gas chromatography/mass spectrometry NWQL, Schedule 2020 Connor and others, 1998 Pesticides and degradates Solid-phase extraction and gas chromatography/mass spectrometry NWQL, Schedule 2003 Zaugg and others, 1995; Lindley and others, 1996; Sandstrom and others, 2001; Madsen and others, 2003 Constituents of special interest Perchlorate Liquid chromatography with mass spectrometry/mass spectrometry (USEPA Method 331.0) Weck Laboratories, Inc., standard operating procedure ORG099.R01 U.S. Environmental Protection Agency, 2005 Inorganic constituents Nutrients Alkaline persulfate digestion, Kjedahl digestion NWQL, Schedule 2755 Fishman, 1993; Patton and Kryskalla, 2003 Major and minor ions, trace elements Atomic absorption spectrometry, colorimetry, ion- exchange chromatography, inductively-coupled plasma atomic emission spectrometry and mass spectrometry NWQL, Schedule 1948 Fishman and Friedman, 1989; Fishman, 1993; Faires, 1993; McLain, 1993; Garbarino, 1999; American Public Health Association, 1998; Garbarino and others, 2006 Arsenic and iron speciation Various techniques of ultraviolet visible (UV-VIS) spectrophotometry and atomic absorbance spectroscopy USGS Trace Metal Laboratory, Boulder, Colorado (USGSTMCO) Stookey, 1970; To and others, 1998; McCleskey and others, 2003 Isotope ratios Stable isotopes of hydrogen (δ2H) and oxygen (δ18O) of water Gaseous hydrogen and carbon dioxide-water equilibration and stable-isotope mass spectrometry USGS Stable Isotope Laboratory, Reston, Virginia (USGSSIVA), NWQL Schedule 1142 Epstein and Mayeda, 1953; Coplen and others, 1991; Coplen, 1994

δ13C of inorganic carbon dissolved

in water and carbon-14 abundance

Accelerator mass spectrometry Woods Hole Oceanographic Institution, 

National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS), NWQL Schedule 2255

Vogel and others, 1987; Donahue 

and others, 1990; McNichol and others, 1992; Gagnon and Jones, 1993; McNichol and others, 1994; Schneider and others, 1994
Appendix 113

Table A1. Analytical methods used for the determination of organic and inorganic constituents by the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) and additional contract laboratories.—Continued[Laboratory entity codes in the USGS National Water Information System (NWIS) for laboratories other than the USGS National Water Quality Laboratory (NWQL) are given in parentheses after the laboratory names. Abbreviation: VOC, volatile organic compound]

Analyte Analytical Method Laboratory and analytical schedule Citation(s)

Isotope ratios—Continued

δ11B of boron dissolved in water Negative thermal-ionization mass spectrometry USGS NRP Metals Isotope Research Lab, 

Menlo Park, California (USGSMICA)

Vengosh and others, 1989; Dwyer and 

Vengosh, 2008

87Sr/86Sr of strontium dissolved in 

water

Chemical separations and thermal-ionization mass 

spectrometry

USGS NRP Metals Isotope Research Lab, 

Menlo Park, California (USGSMICA)

Bullen and others, 1996

Radioactivity and gases

Tritium Electrolytic enrichment-liquid scintillation USGS Stable Isotope and Tritium Laboratory, 

Menlo Park, California (USGSH3CA)

Thatcher and others, 1977

Dissolved noble gases and tritium Helium-3 in-growth and mass spectrometry Lawrence Livermore National Laboratory 

(CA-LLNL)

Moran and others, 2002; Eaton and 

others, 2004

Radon-222 Liquid scintillation counting NWQL, Schedule 1369 American Society for Testing and 

Materials, 1998

Uranium isotopes Chemical separations and alpha-particle 

spectrometry

 Eberline Analytical Services (CA-EBERL), 

NWQL Schedule 1130 

American Society for Testing and 

Materials, 2002 (ASTM D3972)

Gross alpha and gross beta particle 

activity

Alpha and beta activity counting 

(USEPA Method 900.0)

Eberline Analytical Services (CA-EBERL), 

NWQL Schedule 1792

Kreiger and Whittaker, 1980 

Microbial constituents

Escherichia coli (E. coli) and total 

coliform

IDEXX Colilert® test kit (Standard Methods 9223) USGS field measurement American Public Health Association, 

1998
114 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table A2. Preferred analytical schedules for selected constituents collected 

for the Cascade Range and Modoc Plateau (CAMP) study unit, July through 

October 2010, California GAMA Priority Basin Project.

[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: TML, U.S. Geological Survey Trace Metal Laboratory, 

Boulder, Colorado; LLNL, Lawrence Livermore National Laboratory; SITL, U.S. Geological 

Survey Stable Isotope and Tritium Laboratory]

Constituent Primary constituent 

classification

Analytical 

schedules

Preferred 

analytical 

schedule

Results from both methods reported

Alkalinity Water-quality indicator Field, 1948 Field

Arsenic, total Trace element 1948, TML 1948

Iron, total Trace element 1948, TML 1948

pH Water-quality indicator Field, 1948 Field

Specific conductance Water-quality indicator Field, 1948 Field

Table A3. Constituents detected in field blanks and the study reporting level (SRL) analysis for the Cascade Range and Modoc Plateau 

(CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.

[Study reporting levels (SRLs) defined on the basis of CAMP field blanks are equal to the highest concentration measured in the field blanks. Abbreviations: 

LRL, laboratory reporting level; LT-MDL, long term-method detection level; MDL, method detection level; ≤, less than or equal to; E, estimated or having a 

higher degree of uncertainty; μg/L, micrograms per liter; –, not detected]

Constituent

Number of field 

blank detections/

total number of 

field blanks

 LRL, 

LT-MDL, 

MDL, or 

MRL 1

Concentrations detected 

in field blanks

SRL 

concentration

Source 

of 

SRL

Number of 

groundwater

samples

≤-coded

Volatile organic compounds (VOC) (μg/L)

Carbon disulfide 4/10 0.08 0.09, 0.06, E0.02, E0.02 0.04 Fram and others, 2012 2 0

Toluene 0/10 0.018 – 0.69 Fram and others, 2012 3 3

1,2,4-Trimethylbenzene 3/10 0.032 0.069, 0.079, 0.028 0.56 Fram and others, 2012 3 55

Special-interest constituents (μg/L)

Perchlorate 3/10 0.10 0.31, 0.13, 2.72 none none 0

Trace elements (μg/L)

Barium 0/10 0.07 – 0.4 Olsen and others, 2010 1

Chromium 0/10 0.06 – 0.4 Olsen and others, 2010 17

Cobalt 10/10 0.02 0.38, 0.19, 0.05, 0.08, 0.06, 

0.13, 0.17, 0.06, 0.10, 0.13

0.38 CAMP field blanks 41

Copper 1/10 0.5 0.91 1.7 Olsen and others, 2010 39

Iron 1/10 3.2 4 6 Olsen and others, 2010 16

Lead 5/10 0.02 0.02, 1.04, 0.05, 0.02, 0.03 1.04 CAMP field blanks 75

Manganese 6/10 0.2 0.7, 0.3, 0.2, 0.3, 0.2, 0.3 0.7 CAMP field blanks 28

Nickel 1/10 0.09 0.06 0.36 Olsen and others, 2010 35

Tungsten 0/10 0.01 – 0.11 Olsen and others, 2010 44

Zinc 2/10 1.4 2.5, 1.4 4.8 Olsen and others, 2010 26

Arsenic and iron species (μg/L)

Iron (total) 1/10 2 20 6 Olsen and others, 2010 20

1

 LRL is listed for VOCs, LT-MDL is listed for trace elements, and MDL is listed for arsenic and iron species.

2

 Carbon disulfide detections in samples from the CAMP study unit had concentrations greater than the SRL.

3

 Laboratory results for toluene and 1,2,4-trimethylbenzene in samples from the CAMP study unit had concentrations less than the SRLs—toluene (HL‐01, 

E0.02 μg/L and TV-15, 0.03 μg/L) and 1,2,4-trimethylbenzene (55 samples at concentrations ranging from E0.02 μg/L to 0.5 μg/L; median = 0.06 μg/L).
Appendix 115

Table A4A. Quality-control summary for replicate analyses of organic constituents and perchlorate detected in samples collected for 

the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.

[Abbreviations: SD, percent standard deviation; RSD, percent relative standard deviation; ≤, less than or equal to; LRL, laboratory reporting level; SRL, study 

reporting level; nv, no value in category]

Constituent

Number of 

non-detect 

replicates/ 

number of 

replicates

Number of SDs 

greater than 

1⁄2 LRL / number of 

replicates with 

concentration less 

than 5 times the LRL

Concentrations of 

replicates with 

SDs greater 

than 1⁄2 LRL 

(environmental, 

replicate) 

Number of RSDs 

greater than 

10 percent/ number 

of replicates with 

concentration 

greater than 

5 times the LRL

Concentrations 

of replicates with 

RSDs greater 

than 10 percent 

(environmental, 

replicate) 

Volatile organic compounds (VOC) (Schedule 2020)

Benzene 10/10 nv nv nv nv

Carbon disulfide 9/10 0/1 nv nv nv

Chloroform (Trichloromethane) 9/10 0/1 nv nv nv

1,4-Dichlorobenzene 10/10 nv nv nv nv

1,1-Dichloroethene (1,1-DCE) 10/10 nv nv nv nv

o-Ethyl toluene (1-Ethyl-2-methyl 

benzene)

10/10 nv nv nv nv

Isopropylbenzene 10/10 nv nv nv nv

4-Isopropyl-1-methyl benzene 10/10 nv nv nv nv

Methyl tert-butyl ether (MTBE) 10/10 nv nv nv nv

Methylene chloride (Dichloromethane) 10/10 nv nv nv nv

Perchloroethene (PCE, 

Tetrachloroethene)

10/10 nv nv nv nv

n-Propylbenzene 10/10 nv nv nv nv

1,2,3,4-Tetramethylbenzene 10/10 nv nv nv nv

1,2,3,5-Tetramethylbenzene 10/10 nv nv nv nv

1,1,1-Trichloroethane (1,1,1-TCA) 10/10 nv nv nv nv

Trichlorotrifluoroethane (CFC-113) 10/10 nv nv nv nv

1,2,3-Trimethylbenzene 10/10 nv nv nv nv

1,3,5-Trimethylbenzene 10/10 nv nv nv nv

Pesticides and pesticide degradates (Schedule 2003)

Atrazine 10/10 nv nv nv nv

Carbaryl 10/10 nv nv nv nv

Deethylatrazine (2-Chloro-4-

isopropylamino-6-amino-s-triazine)

8/10 0/2 nv nv nv

3,4-Dichloroaniline 10/10 nv nv nv nv

Hexazinone 9/10 0/1 nv nv nv

Metalaxyl 10/10 nv nv nv nv

Prometon 10/10 nv nv nv nv

Simazine 10/10 nv nv nv nv

Tebuthiuron 10/10 nv nv nv nv

Constituent of special interest - Perchlorate

Perchlorate 7/10 0/3 nv nv nv
116 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table A4B. Quality-control summary for replicate analyses of inorganic constituents and isotope tracers detected in samples 

collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin 

Project.

[Types of reporting levels (RL): LT-MDL or SRL are used for trace elements (table 10); LT-MDL or MDL are used for nutrients (table 9); LT-MDL or MRL are 

used for major ions (table 11); MDL is used for oxidation-reduction species (table 15); MU is used for isotope tracers (table 16). Abbreviations: SD, percent 

standard deviation; RSD, percent relative standard deviation; LT-MDL, long-term method detection level; SRL, study reporting level; MDL, method detection 

limit; MRL, minimum reporting level; MU, method uncertainty; μg/L, micrograms per liter; H, hydrogen; O, oxygen; C, carbon; mg/L, milligrams per liter; <, 

less than; ≤, less than or equal to; nv, no value in category]

Constituent

Number of 

non-detect 

or ≤-coded 

replicates/ 

total number of 

replicates 

Replicates with concentrations less than 

or equal to 5 times the RL

Replicates with concentrations 

greater than 5 times the RL

Number of SDs 

greater than 1⁄2 

the RL/ 

number of 

replicates

Concentrations

of replicates 

with SDs 

greater than 

1⁄2 the RL 

(environmental, 

replicate) 

Number of RSDs 

greater than 

10 percent/ 

number of 

replicates

Concentrations of 

replicates 

with RSDs 

greater than 

10 percent 

(environmental, 

replicate) 

Trace elements (μg/L)

Aluminum 0/10 3/9 (5.4, 3.9; 5.6, 4.2; 1.8, <1.7) 0/1 nv

Antimony 6/10 0/4 nv nv nv

Arsenic 0/10 0/2 nv 0/8 nv

Barium 0/10 0/1 nv 0/9 nv

Beryllium 9/10 0/1 nv nv nv

Boron 0/10 0/4 nv 0/6 nv

Cadmium 8/10 1/2 (0.02, <0.02) nv nv

Chromium 2/10 0/6 nv 0/2 nv

Cobalt 8/10 0/2 nv nv nv

Copper 8/10 0/2 nv nv nv

Iron 9/10 0/1 nv nv nv

Lead 9/10 0/1 nv nv nv

Lithium 0/10 0/4 nv 0/6 nv

Manganese 8/10 nv nv 0/2 nv

Molybdenum 0/10 0/3 nv 0/7 nv

Nickel 9/10 0/1 nv nv nv

Selenium 6/10 0/3 nv 0/1 nv

Silver 9/10 1/1 (0.01, <0.01) nv nv

Strontium 0/10 nv nv 0/10 nv

Thallium 9/10 1/1 (0.01, <0.01) nv nv

Tungsten 7/10 0/2 nv 0/1 nv

Uranium 1/10 0/1 nv 0/8 nv

Vanadium 1/10 nv nv 0/9 nv

Zinc 7/10 1/1 (5.0, ≤4.7) 1/2 (24.3, 20.0)

Nutrients (mg/L)

Ammonia (as nitrogen) 8/10 nv nv 0/2 nv

Nitrate plus nitrite (as nitrogen) 1/10 0/5 nv 0/4 nv

Nitrite (as nitrogen) 8/10 1/1 (0.001, <0.001) 0/1 nv

Total nitrogen 4/10 1/2 (<0.05, 0.05) 0/4 nv

Orthophosphate (as phosphorus) 0/10 nv nv 0/10 nv
Appendix 117

Table A4B. Quality-control summary for replicate analyses of inorganic constituents and isotope tracers detected in samples 

collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin 

Project.—Continued

[Types of reporting levels (RL): LT-MDL or SRL are used for trace elements (table 10); LT-MDL or MDL are used for nutrients (table 9); LT-MDL or MRL are 

used for major ions (table 11); MDL is used for oxidation-reduction species (table 15); MU is used for isotope tracers (table 16). Abbreviations: SD, percent 

standard deviation; RSD, percent relative standard deviation; LT-MDL, long-term method detection level; SRL, study reporting level; MDL, method detection 

limit; MRL, minimum reporting level; MU, method uncertainty; μg/L, micrograms per liter; H, hydrogen; O, oxygen; C, carbon; , mg/L, milligrams per liter; <, 

less than; ≤, less than or equal to; nv, no value in category]

Constituent

Number of 

non-detect 

or ≤-coded 

replicates/ 

total number of 

replicates 

Replicates with concentrations less than 

or equal to 5 times the RL

Replicates with concentrations 

greater than 5 times the RL

Number of SDs 

greater than 1⁄2 

the RL/ 

number of 

replicates

Concentrations

of replicates 

with SDs 

greater than 

1⁄2 the RL 

(environmental, 

replicate) 

Number of RSDs 

greater than 

10 percent/ 

number of 

replicates

Concentrations of 

replicates 

with RSDs 

greater than 

10 percent 

(environmental, 

replicate) 

Major and minor ions, silica, and total dissolved solids (TDS) (mg/L)

Bromide 5/10 1/3 (0.02, 0.03) 0/2 nv

Calcium 0/10 nv nv 0/10 nv

Chloride 0/10 0/1 nv 0/9 nv

Fluoride 5/10 0/1 nv 0/4 nv

Iodide 7/10 0/2 nv 0/1 nv

Magnesium 0/10 nv nv 0/10 nv

Potassium 0/10 nv nv 0/10 nv

Sodium 0/10 nv nv 0/10 nv

Sulfate 1/10 0/3 nv 0/6 nv

Silica (as SiO2) 0/10 nv nv 0/10 nv

TDS 0/10 nv nv 2/10 (141, 116; 

77, 104)

Arsenic and iron species (μg/L)

Arsenic (total) 3/10 nv nv 0/7 nv

Arsenic (III) 9/10 nv nv 0/1 nv

Iron (total) 9/10 0/1 nv nv nv

Iron (II) 8/10 1/1 (5.0, 3.3) 0/1 nv

Isotope tracers 

δ2H in water 0/10 nv nv 0/10 nv

δ18O in water 0/10 nv nv 0/10 nv

δ13C in dissolved inorganic carbon 0/10 nv nv 0/10 nv

Carbon-14 0/10 nv nv 0/10 nv
118 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table A4C. Quality-control summary for replicate analyses of radioactive constiuents detected in samples collected for the Cascade 

Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.

[For activities of radiochemical constituents, a replicate pair of analyses is defined as acceptable if the p-value for the normalized absolute difference is less than 

the significance level, α = 0.05. Abbreviations: >, greater than; pCi/L, picocuries per liter; ±, plus or minus; nv, no value in category; –, not detected (value is 

below ssLC); ssLC, sample-specific critical level]

Constituent

Number of pairs with 

p > 0.05 /

total number of 

replicate pairs

Activites in pCi/L for replicate pairs

with p > 0.05

(environmental, replicate)

result ± CSU

Tritium 1/8 (7.40 ± 0.39, 8.70 ± 0.47)

Uranium-234 0/2 nv

Uranium-235 0/2 nv

Uranium-238 1/2 (–, 0.042 ± 0.013)

Radon-222 1/10 (420 ± 27, 360 ± 23) 

Gross alpha radioactivity, 72-hour count 1/10 (–, 1.50 ± 0.62)

Gross alpha radioactivity, 30-day count 0/10 nv

Gross beta radioactivity, 72-hour count 0/10 1 nv

Gross beta radioactivity, 30-day count 1/10 (–, 1.63 ± 0.41)

1

 Includes an acceptable replicate pair collected from QV-04 counted 6 days after collection.

Table A4D. Quality-control summary for replicate analyses 

of microbial constituents detected in samples collected for the 

Cascade Range and Modoc Plateau (CAMP) study unit, July 

through October 2010, California GAMA Priority Basin Project.

[Abbreviations: –, not detected; D, detected]

Constituent

Total 

number 

of 

replicates

Number 

of 

(–, –) 

replicates

Number 

of 

(D, D) 

replicates

Number of 

(D, –) 

or (–, D) 

replicates

Microbial constituents

E. coli 6 6 0 0

Total coliform 6 4 0 1 2

1

 Potential change in sample collection line may have affected replicate 

sample.
Appendix 119

Table A5A. Quality-control summary for matrix-spike recoveries of volatile organic compounds (VOCs) in samples collected for the 

Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.

[Acceptable recovery range is between 70 and 130 percent. Abbreviation: D, detected in groundwater samples (table 6); –, not detected]

Constituent

Number of 

spike 

samples

Minimum 

recovery 

(percent)

Median 

recovery 

(percent)

Maximum 

recovery 

(percent)

Detected in 

groundwater 

samples

Acetone 9 88 100 141 – (1)

Acrylonitrile 9 80 98 112 –

tert-Amyl methyl ether (TAME) 9 83 95 104 –

Benzene 9 95 100 107 D

Bromobenzene 9 91 95 112 –

Bromochloromethane 9 92 100 110 –

Bromodichloromethane 9 79 86 101 –

Bromoform (Tribromomethane) 9 79 89 107 –

Bromomethane (Methyl bromide) 9 79 106 122 –

n-Butylbenzene 9 71 92 102 –

sec-Butylbenzene 9 87 99 108 –

tert-Butylbenzene 9 91 103 107 –

Carbon disulfide 9 68 85 99 D

Carbon tetrachloride (Tetrachloromethane) 9 83 95 105 –

Chlorobenzene 9 91 94 102 –

Chloroethane 9 70 100 124 –

Chloroform (Trichloromethane) 9 93 103 120 D

Chloromethane 9 80 110 136 –

3-Chloropropene 9 79 94 103 –

2-Chlorotoluene 9 92 103 114 –

4-Chlorotoluene 9 91 99 114 –

Dibromochloromethane 9 82 90 99 –

1,2-Dibromo-3-chloropropane (DBCP) 9 76 93 106 –

1,2-Dibromoethane (EDB) 9 91 101 108 –

Dibromomethane 9 90 97 106 –

1,2-Dichlorobenzene 9 96 102 123 –

1,3-Dichlorobenzene 9 96 101 114 –

1,4-Dichlorobenzene 9 99 102 117 D

trans-1,4-Dichloro-2-butene 9 62 86 102 –

Dichlorodifluoromethane (CFC-12) 9 70 87 126 –

1,1-Dichloroethane (1,1-DCA) 9 84 98 114 –

1,2-Dichloroethane (1,2-DCA) 9 97 103 115 –

1,1-Dichloroethene (1,1-DCE) 9 84 99 108 D

cis-1,2-Dichloroethene (cis-1,2-DCE) 9 94 98 104 –

trans-1,2-Dichloroethene (trans-1,2-DCE) 9 87 99 106 –

1,2-Dichloropropane 9 89 96 100 –

1,3-Dichloropropane 9 94 101 106 –

2,2-Dichloropropane 9 72 85 92 –

1,1-Dichloropropene 9 87 92 97 –

cis-1,3-Dichloropropene 9 82 87 96 –

trans-1,3-Dichloropropene 9 76 88 97 –

Diethyl ether 9 82 103 109 –

Diisopropyl ether (DIPE) 9 84 100 105 –

Ethylbenzene 9 88 92 100 –

Ethyl tert-butyl ether (ETBE) 9 86 95 101 –

Ethyl methacrylate 9 83 86 93 –

o-Ethyl toluene (1-Ethyl-2-methyl benzene) 9 91 99 109 D
120 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table A5A. Quality-control summary for matrix-spike recoveries of volatile organic compounds (VOCs) in samples collected for the 

Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued

[Acceptable recovery range is between 70 and 130 percent. Abbreviation: D, detected in groundwater samples (table 6); –, not detected]

Constituent

Number of 

spike 

samples

Minimum 

recovery 

(percent)

Median 

recovery 

(percent)

Maximum 

recovery 

(percent)

Detected in 

groundwater 

samples

Hexachlorobutadiene 9 80 87 111 –

Hexachloroethane 9 78 92 113 –

2-Hexanone (n-Butyl methyl ketone) 9 82 96 108 –

Iodomethane (Methyl iodide) 9 93 108 117 –

Isopropylbenzene 9 86 92 99 D

4-Isopropyl-1-methyl benzene 9 78 95 103 D

Methyl acrylate 9 91 95 105 –

Methyl acrylonitrile 9 95 105 113 –

Methyl tert-butyl ether (MTBE) 9 85 106 119 D

Methyl iso-butyl ketone (MIBK) 9 84 90 102 –

Methylene chloride (Dichloromethane) 9 83 103 118 D

Methyl ethyl ketone (2-butanone, MEK) 9 87 96 111 –

Methyl methacrylate 9 82 90 92 –

Naphthalene 9 79 91 101 –

Perchloroethene (PCE, Tetrachloroethene) 9 93 125 159 D

n-Propylbenzene 9 83 93 102 D

Styrene 9 79 93 103 –

1,1,1,2-Tetrachloroethane 9 84 94 110 –

1,1,2,2-Tetrachloroethane 9 90 93 109 –

Tetrahydrofuran 9 94 105 119 – (1)

1,2,3,4-Tetramethylbenzene 9 78 94 111 D

1,2,3,5-Tetramethylbenzene 9 77 96 116 D

Toluene 9 97 104 111 – (1)

1,2,3-Trichlorobenzene 9 89 97 114 –

1,2,4-Trichlorobenzene 9 84 95 106 –

1,1,1-Trichloroethane (1,1,1-TCA) 9 94 101 116 D

1,1,2-Trichloroethane (1,1,2-TCA) 9 92 97 109 –

Trichloroethene (TCE) 9 85 94 103 –

Trichlorofluoromethane (CFC-11) 9 93 110 131 –

1,2,3-Trichloropropane (1,2,3-TCP) 9 92 97 117 –

Trichlorotrifluoroethane (CFC-113) 9 87 99 127 D

1,2,3-Trimethylbenzene 9 87 102 118 D

1,2,4-Trimethylbenzene 9 84 91 145 – (1)

1,3,5-Trimethylbenzene 9 91 100 109 D

Vinyl bromide (Bromoethene) 9 95 99 113 –

Vinyl chloride (Chloroethene) 9 69 97 130 –

m- and p-Xylene 9 89 99 105 –

o-Xylene 9 87 95 105 –

1

 These constituents had concentrations less than the study reporting levels defined on the basis of examination of quality-control samples collected between 

May 2004 and September 2010 for the first 32 study units of the California GAMA Priority Basin Project (Fram and others, 2012).
Appendix 121

Table A5B. Quality-control summary for matrix-spike recoveries of pesticides and pesticide degradates in samples collected for the 

Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.

[Acceptable recovery range is between 70 and 130 percent. Abbreviation: D, detected in groundwater samples (table 7); –, not detected]

Constituent

Number of 

spike 

samples

Minimum

 recovery

(percent)

Median 

recovery 

(percent)

Maximum 

recovery 

(percent)

Detected in 

groundwater 

samples

Acetochlor 9 84 97 184 –(1)

Alachlor 9 80 95 136 –

Atrazine 9 79 101 114 D

Azinphos-methyl 9 86 98 121 –

Azinphos-methyl oxon 9 45 75 100 –

Benfluralin 9 67 77 94 –

Carbaryl 9 95 114 164 D

2-Chloro-2,6-diethylacetanilide 9 87 104 118 –

4-Chloro-2-methylphenol 9 65 73 94 –

Chlorpyrifos 9 75 87 104 –

Chlorpyrifos oxon 9 16 34 50 –

Cyfluthrin 9 46 62 112 –

Cypermethrin 9 45 58 100 –

Dacthal (DCPA) 9 97 109 111 –

Deethylatrazine (2-Chloro-4-

isopropylamino-6-amino-striazine)

9 92 109 138 D

Desulfinylfipronil 9 79 101 135 –

Desulfinylfipronil amide 9 69 90 130 –

Diazinon 9 85 100 109 –

3,4-Dichloroaniline 9 76 84 99 D

Dichlorvos 9 12 22 51 –

Dicrotophos 9 24 35 48 –

Dieldrin 9 69 93 108 –

2,6-Diethylaniline 9 93 97 110 –

Dimethoate 9 51 64 87 –

Ethion 9 65 79 117 –

Ethion monoxon 9 76 98 119 –

2-Ethyl-6-methylaniline 9 74 92 106 –

Fenamiphos 9 71 95 136 –

Fenamiphos sulfone 9 74 95 113 –

Fenamiphos sulfoxide 9 7 17 33 –

Fipronil 9 82 108 136 –

Fipronil sulfide 9 85 101 142 –

Fipronil sulfone 9 67 79 101 –

Fonofos 9 72 93 97 –

Hexazinone 9 52 69 98 D

Iprodione 9 68 79 128 –

Isofenphos 9 81 97 137 –

Malaoxon 9 71 91 111 –

Malathion 9 74 97 121 –

Metalaxyl 9 87 109 157 D

Methidathion 9 87 95 111 –

Metolachlor 9 78 92 131 –

Metribuzin 9 76 94 152 –

Myclobutanil 9 78 81 125 –

1-Naphthol 9 39 61 86 –
122 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

Table A5B. Quality-control summary for matrix-spike recoveries of pesticides and pesticide degradates in samples collected for the 

Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.—Continued

[Acceptable recovery range is between 70 and 130 percent. Abbreviation: D, detected in groundwater samples (table 7); –, not detected]

Constituent

Number of 

spike 

samples

Minimum

 recovery

(percent)

Median 

recovery 

(percent)

Maximum 

recovery 

(percent)

Detected in 

groundwater 

samples

Paraoxon-methyl 9 54 73 101 –

Parathion-methyl 9 81 104 149 –

Pendimethalin 9 85 102 133 –

cis-Permethrin 9 51 67 146 –

Phorate 9 66 76 91 –

Phorate oxon 9 74 112 130 –

Phosmet 9 33 41 72 –

Phosmet oxon 9 23 37 57 –

Prometon 9 75 97 116 D

Prometryn 9 82 102 130 –

Pronamide (Propyzamide) 9 90 103 120 –

Simazine 9 82 97 117 D

Tebuthiuron 9 95 143 179 D

Terbufos 9 70 85 100 –

Terbufos oxon sulfone 9 58 83 116 –

Terbuthylazine 9 83 103 117 –

Tribufos 9 51 61 105 –

Trifluralin 9 70 84 103 –

1

 These constituents had concentrations less than the study reporting levels defined on the basis of examination of quality-control samples collected between 

May 2004 and September 2010 for the first 32 study units of the California GAMA Priority Basin Project (Fram and others, 2012).
Appendix 123

Table A6. Quality-control summary for surrogate recoveries of volatile organic compounds (VOCs) and pesticides and pesticide degradates in samples collected for the Cascade Range and Modoc Plateau (CAMP) study unit, July through October 2010, California GAMA Priority Basin Project.

Surrogate Analytical schedule

Constitutent or 

constituent 

class 

analyzed

Number 

of blank 

analyses

Median 

recovery 

in blanks 

(percent)

Number of 

surrogate 

recoveries less 

than 70 percent

in blanks

Number of 

surrogate 

recoveries greater 

than 130 percent

in blanks

Number

of 

sample 

analyses

Median 

recovery in 

samples 

(percent)

Number of 

surrogate 

recoveries 

less than 

70 percent 

in samples

Number of 

surrogate 

recoveries 

greater than 

130 percent

in samples

1-Bromo-4-fluorobenzene 2020 VOC 10 84 0 0 90 83 1 01,2-Dichloroethane-d4 2020 VOC 10 119 0 2 90 125 0 24

Toluene-d8 2020 VOC 10 93 0 0 90 93 0 0Diazinon-d10 2003 Pesticide 9 82 1 0 90 78 21 0α-HCH-d6 2003 Pesticide 9 91 0 0 90 90 1 0
124 Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: Results from the California GAMA Program

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Shelton and others—Groundwater-Quality Data in the Cascade Range and Modoc Plateau Study Unit, 2010: 

 Results from the California GAMA Program—Data Series 688