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 South Coast Range-Coastal 

Study Unit, 2008: Results from the California GAMA Program

U.S. Department of the Interior

U.S. Geological Survey

Data Series 504

101

San Luis Obispo

Santa Maria

Lompoc Pacific Ocean

154

166

1

1
Cover photographs:

Top right: Irrigation well, Lompoc, California. (Photograph taken by Dara Goldrath, U.S. Geological Survey.)

Bottom center: Marigold farm near Lompoc, California. (Photograph taken by Cathy Munday, U.S. Geological 

Survey.) 
Groundwater-Quality Data in the South 

Coast Range–Coastal Study Unit, 2008: 

Results from the California GAMA Program

By Timothy M. Mathany, Carmen A. Burton, Michael Land, and Kenneth Belitz

Prepared in cooperation with the California State Water Resources Control Board

Data Series 504

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2010

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Mathany, T.M., Burton, C.A., Land, Michael, and Belitz, Kenneth, 2010, Groundwater-quality data in the South Coast 

Range–Coastal study unit, 2008: Results from the California GAMA program: U.S. Geological Survey Data Series 504, 

106 p. 
iii

Contents

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

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

Purpose and Scope ..............................................................................................................................5

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

Methods ..........................................................................................................................................................7

Study Design..........................................................................................................................................7

Sample Collection and Analysis.......................................................................................................11

Data Reporting.....................................................................................................................................11

Quality Assurance...............................................................................................................................11

Water-Quality Results ................................................................................................................................11

Quality-Control Results ......................................................................................................................11

Comparison Thresholds.....................................................................................................................12

Groundwater-Quality Data ................................................................................................................13

Field Water-Quality Indicators ................................................................................................13

Organic Constituents.................................................................................................................14

Constituents of Special Interest..............................................................................................14

Inorganic Constituents..............................................................................................................14

Isotopic Tracers and Dissolved Gases...................................................................................15

Radioactive Constituents..........................................................................................................16

Future Work ..................................................................................................................................................16

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

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

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

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

Appendix .......................................................................................................................................................76

Sample Collection and Analysis.......................................................................................................76

Data Reporting.....................................................................................................................................78

Reporting Limits..........................................................................................................................78

Notation.......................................................................................................................................79

Constituents on Multiple Analytical Schedules....................................................................79

Quality Assurance...............................................................................................................................80

Blanks .........................................................................................................................................80

Blank Collection and Analysis ........................................................................................80

Assessment of Blank Results .........................................................................................80

Replicates....................................................................................................................................82

Matrix Spikes..............................................................................................................................83

Surrogates...................................................................................................................................83

Quality-Control Results ......................................................................................................................83

Detections in Field and Source-Solution Blanks and Equipment Blank...........................83

Variability in Replicate Samples..............................................................................................85

Matrix-Spike Recoveries..........................................................................................................86

Surrogate Compound Recoveries...........................................................................................87
iv

Figures

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

Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and

Assessment (GAMA) study unit ......................................................... 4

Figure 2. Map of the South Coast Range–Coastal (SCRC) Groundwater Ambient

Monitoring and Assessment (GAMA) study unit showing the location and

boundaries of the California Department of Water Resources (CDWR) defined

groundwater basins, the locations of areas outside of the CDWR-defined

groundwater basins that are included in the study unit, the location of major

cities, topographic features, and hydrologic features ................................. 6

Figure 3. Map of the South Coast Range–Coastal (SCRC) Groundwater Ambient

Monitoring and Assessment (GAMA) study unit showing the boundaries of the

Basins and Uplands study areas, the location of public-supply wells with a

record in the California Department of Public Health (CDPH) Database, major

cities, major roads, topographic features, and hydrologic features .................. 8

Figure 4. Map of the South Coast Range–Coastal (SCRC) Groundwater Ambient

Monitoring and Assessment (GAMA) study unit showing the distribution of the

Basins and Uplands study area-grid cells, the location of sampled grid and

understanding wells and surface-water sites, major cities, major roads,

topographic features, and hydrologic features ....................................... 10

Tables

Table 1. Identification, sampling, and construction information for wells and

identification and sampling information for surface-water sites sampled for the

South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and

Assessment (GAMA) study, California, May to December 2008 ..................... 26

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

for the slow, fast, and special study well sampling schedules and the

surface-water schedule in the South Coast Range–Coastal (SCRC)

Groundwater Ambient Monitoring and Assessment (GAMA) study, California,

May to December 2008 ..................................................................... 29

Table 3A. Volatile organic compounds (VOC), primary uses or sources, comparative

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

National Water Quality Laboratory Schedule 2020 .................................... 30

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

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

National Water Quality Laboratory Schedule 2003 .................................... 34

Table 3C. Polar pesticides and metabolites, primary uses or sources, comparative

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

National Water Quality Laboratory Schedule 2060 .................................... 36

Table 3D. Pharmaceutical compounds, primary uses or sources, comparative thresholds,

and reporting information for the U.S. Geological Survey (USGS) National Water

Quality Laboratory Schedule 2080 ......................................................... 38

Table 3E. Constituents of special interest (perchlorate, N-nitrosodimethylamine [NDMA],

and 1,2,3-TCP), primary uses or sources, comparative thresholds, and reporting

information for Weck Laboratories, Inc. analyses....................................... 39

Table 3F. Trace elements, comparative thresholds, and reporting information for the U.S.

Geological Survey (USGS) National Water Quality Laboratory Schedule 1948 ...... 40
v

Table 3G. Nutrients and dissolved organic carbon (DOC), comparative thresholds, and

reporting information for the U.S. Geological Survey (USGS) National Water

Quality Laboratory Schedules 2755 and 2702 and Laboratory Code 2612 ............ 41

Table 3H. Major and minor ions, silica, total dissolved solids (TDS), and alkalinity,

comparative thresholds, and reporting information for the U.S. Geological

Survey (USGS) National Water Quality Laboratory Schedule 1948 .................. 42

Table 3I. Arsenic and iron species, comparative thresholds, and reporting information for

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

analyses .................................................................................... 42

Table 3J. Isotopic and radioactive constituents, comparative thresholds, and reporting

information for laboratory analyses ...................................................... 43

Table 3K. Dissolved gases and tritium, comparison thresholds and reporting information

for the U.S. Geological Survey (USGS) Chlorofluorocarbon Laboratory and

Lawrence Livermore National Laboratory analyses .................................... 44

Table 4. Field water-quality indicators in samples collected for the South Coast

Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment

(GAMA) study, California, May to December 2008....................................... 45

Table 5. Volatile organic compounds (VOC) detected in samples collected for the South

Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and

Assessment (GAMA) study, California, May to December 2008 ..................... 49

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

South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and

Assessment (GAMA) study, California, May to December 2008 ..................... 55

Table 6B. Polar pesticides and metabolites detected in samples collected for the South

Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and

Assessment (GAMA) study, California, May to December 2008 ..................... 58

Table 7. Perchlorate detected in the samples collected for the South Coast

Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment

(GAMA) study, California, May to December 2008....................................... 59

Table 8. Trace elements detected in the samples collected for the South Coast

Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment

(GAMA) study, California, May to December 2008....................................... 60

Table 9. Nutrients and dissolved organic carbon (DOC) detected in samples collected

for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring

and Assessment (GAMA) study, California, May to December 2008 .................. 64

Table 10. Major and minor ions, silica, and total dissolved solids (TDS) detected in

samples collected for the South Coast Range–Coastal (SCRC) Groundwater

Ambient Monitoring and Assessment (GAMA) study, California, May to

December 2008 .............................................................................. 67

Table 11. Species of inorganic arsenic and iron detected in samples collected for the

South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and

Assessment (GAMA) study, California, May to December 2008 ..................... 69

Table 12. Results for analyses of stable isotope ratios, tritium activity, and carbon-14

abundance detected in samples collected for the Southern Coast

Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment

(GAMA) study, California, May to December 2008....................................... 70

Table 13. Results for analyses of dissolved gases detected in samples collected for the

Southern Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and

Assessment (GAMA) study, California, May to December 2008 ..................... 73
vi

Table 14. Gross alpha and gross beta radioactivity detected in samples collected for the

South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and

Assessment (GAMA) study, California, May to December 2008 ..................... 74

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 contract laboratories .......................................... 88

Table A2. Preferred analytical schedules for constituents appearing on multiple

schedules for samples collected for the South Coast Range–Coastal (SCRC)

Groundwater Ambient Monitoring and Assessment (GAMA) study, California,

May to December 2008 ..................................................................... 90

Table A3. Constituents detected in blanks collected for the South Coast Range–Coastal

(SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study,

California, May to December 2008 ...................................................... 91

Table A4A. Quality-control summary for replicate analyses of organic constituents

detected in samples collected for the South Coast Range–Coastal (SCRC)

Groundwater Ambient Monitoring and Assessment (GAMA) study, California,

May to December 2008 ..................................................................... 92

Table A4B. Quality-control summary for replicate analyses of inorganic constituents,

isotope tracers, and radioactivity detected in samples collected for the South

Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and

Assessment (GAMA) study, California, May to December 2008 ..................... 94

Table A4C. Quality-control summary for replicate analyses of gross alpha and gross beta

radioactivity detected in samples collected for the South Coast Range–Coastal

(SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study,

California, May to December 2008......................................................... 97

Table A5A. Quality-control summary for matrix-spike recoveries of volatile organic

compounds (VOC) in samples collected for the South Coast Range–Coastal

(SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study,

California, May to December 2008......................................................... 98

Table A5B. Quality-control summary for matrix-spike recoveries of pesticides and pesticide

degradates in samples collected for the South Coast Range–Coastal (SCRC)

Groundwater Ambient Monitoring and Assessment (GAMA) study, California,

May to December 2008 .....................................................................100

Table A5C. Quality-control summary for matrix-spike recoveries of polar pesticides and

metabolites in samples collected for the South Coast Range–Coastal (SCRC)

Groundwater Ambient Monitoring and Assessment (GAMA) study, California,

May to December 2008 .....................................................................102

Table A5D. Quality-control summary for matrix-spike recoveries of constituents of special

interest in samples collected for the South Coast Range–Coastal (SCRC)

Groundwater Ambient Monitoring and Assessment (GAMA) study, California,

May to December 2008 .....................................................................104

Table A5E. Quality-control summary for matrix-spike recoveries of gross alpha and gross

beta radioactivity in samples collected for the South Coast Range–Coastal

(SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study,

California, May to December 2008.........................................................104

Table A6. Quality-control summary for surrogate recoveries of volatile organic

compounds (VOC), pesticides and pesticide degradates, and polar pesticides

and metabolites in samples collected for the South Coast Range–Coastal

(SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study,

California, May to December 2008.........................................................105
vii

Abbreviations and Acronyms

(Additional information or clarification given in parentheses)

AL-US action level (USEPA)

BQS U.S. Geological Survey Office of Water Quality Branch of Quality Systems

CAS Chemical Abstract Service (American Chemical Society)

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

CSU combined standard uncertainty

E estimated or having a higher degree of uncertainty

GAMA Groundwater Ambient Monitoring and Assessment program

GPS Global Positioning System

HAL-US lifetime health advisory level (USEPA)

HPLC high-performance liquid chromatography

LRL laboratory reporting level

LSD land surface datum

LT-MDL long-term method detection level

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)

PCFF portable computer field forms program designed for USGS sampling

QA quality assurance

QC quality control

RL reporting level

RPD relative percent difference

RSD relative standard deviation

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

SCRC South Coast Range–Coastal study unit

SCRC-B South Coast Range–Coastal Basins study area

SCRC-H South Coast Range–Coastal Uplands study area 

SCRC-SW South Coast Range–Coastal study unit surface-water site (sample)

SCRC-U South Coast Range–Coastal study unit understanding (well)

SD standard deviation

SMCL-CA secondary maximum contaminant level (CDPH)
viii

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

ssLC sample-specific critical level

US United States

UV ultraviolet

V analyte detected in sample and associated blank; thus, data are not included in 

groundwater quality assessment

VCDT Vienna Canon Diablo Troilite (the international reference standard for sulfur isotopes)

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

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 (USGS)

NELAP National Environmental Laboratory Accreditation Program

NWQL National Water Quality Laboratory (USGS)

NRP National Research Program (USGS)

SWRCB State Water Resources Control Board

TML Trace Metal Laboratory (USGS)

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

Selected Chemical Names

1,2,3-TCP 1,2,3-Trichloropropane

CaCO3 calcium carbonate

CO3

–2 carbonate

CFC chlorofluorocarbon

H2O water

HCl hydrochloric acid

HCO3

– bicarbonate

MTBE methyl tert-butyl ether

Na2S2O3 sodium thiosulfate

NDMA N-nitrosodimethylamine

NO2

–+NO3– nitrite plus nitrate, as nitrogen

PCE perchloroethene (tetrachloroethene)

SiO2 silicon dioxide
ix

TCE trichloroethene

TDS total dissolved solids

THM trihalomethane

VOC volatile organic compound

Selected Terms and Symbols

cm3 STP/g cubic centimeters of gas at standard temperature and pressure (0 degrees Celsius and 1 

atmosphere of pressure) per gram of water

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

isotope of that element, relative to a standard reference material, expressed as per mil

= equal to

> greater than 

≥ greater than or equal to

< less than

≤ less than or equal to

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

— not detected

pH measure of the acidity or basicity of water

pK1,2 acid dissociation constants of carbonic acid

pKw acid dissociation constant of water

± plus or minus

* value is above threshold level

** value is above upper threshold level

Notes

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

°F=(1.8×°C)+32.

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.

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

25°C).

Turbidity is given in nephelometric turbidity units (NTRU). 

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

or micrograms per liter (μg/L). 

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

to parts per billion (ppb). 

Concentrations of radioactive constituents in water are given in picocuries per liter (pCi/L). 
x

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Groundwater-Quality Data in the South Coast 

Range–Coastal Study Unit, 2008: Results from the 

California GAMA Program

By Timothy M. Mathany, Carmen A. Burton, Michael Land, and Kenneth Belitz

Abstract 

Groundwater quality in the approximately 766-squaremile South Coast Range–Coastal (SCRC) study unit was 

investigated from May to December 2008, as part of 

the Priority Basins Project of the Groundwater Ambient 

Monitoring and Assessment (GAMA) Program. The 

GAMA Priority Basins Project was developed in response 

to legislative mandates (Supplemental Report of the 1999 

Budget Act 1999-00 Fiscal Year; and, the Groundwater 

Quality Monitoring Act of 2001 [Sections 10780-10782.3 

of the California Water Code, Assembly Bill 599]) to assess 

and monitor the quality of groundwater in California, and 

is being conducted by the U.S. Geological Survey (USGS) 

in cooperation with the California State Water Resources 

Control Board (SWRCB). The SCRC study unit was the 25th 

study unit to be sampled as part of the GAMA Priority Basins 

Project.

The SCRC study unit was designed to provide a spatially 

unbiased assessment of untreated groundwater quality in the 

primary aquifer systems and to facilitate statistically consistent 

comparisons of untreated groundwater quality throughout 

California. The primary aquifer systems (hereinafter referred 

to as primary aquifers) were defined as that part of the aquifer 

corresponding to the perforation interval of wells listed in the 

California Department of Public Health (CDPH) database for 

the SCRC study unit. The quality of groundwater in shallow 

or deep water-bearing zones may differ from the quality of 

groundwater in the primary aquifers; shallow groundwater 

may be more vulnerable to surficial contamination.

In the SCRC study unit, groundwater samples were 

collected from 70 wells in two study areas (Basins and 

Uplands) in Santa Barbara and San Luis Obispo Counties. 

Fifty-five of the wells were selected using a spatially 

distributed, randomized grid-based method to provide 

statistical representation of the study unit (grid wells), 

and 15 wells were selected to aid in evaluation of specific 

water-quality issues (understanding wells). In addition to the 

70 wells sampled, 3 surface-water samples were collected 

in streams near 2 of the sampled wells in order to better 

comprehend the interaction between groundwater and surface 

water in the area.

The groundwater samples were analyzed for organic 

constituents (volatile organic compounds [VOC], pesticides 

and pesticide degradates, polar pesticides and metabolites, 

and pharmaceutical compounds), constituents of special 

interest (perchlorate, N-nitrosodimethylamine [NDMA], 

and 1,2,3-TCP), naturally occurring inorganic constituents 

(trace elements, nutrients, dissolved organic carbon [DOC], 

major and minor ions, silica, total dissolved solids [TDS], 

and alkalinity), and radioactive constituents (gross alpha and 

gross beta radioactivity). Naturally occurring isotopes (stable 

isotopes of hydrogen and oxygen in water, stable isotopes 

of nitrogen and oxygen in dissolved nitrate, stable isotopes 

of sulfur in dissolved sulfate, stable isotopes of carbon in 

dissolved inorganic carbon, activities of tritium, and carbon-14 

abundance), and dissolved gases (including noble gases) 

also were measured to help identify the sources and ages of 

the sampled groundwater. In total, 298 constituents and field 

water-quality indicators were investigated.

Three types of quality-control samples (blanks, replicates, 

and matrix-spikes) were collected at approximately 3 to 

12 percent of the wells in the SCRC study unit, and the results 

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

for the groundwater samples. Field 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. Differences between replicate samples generally 

were less than 10 percent relative and/or standard deviation, 

indicating acceptable analytical reproducibility. Matrixspike recoveries were within the acceptable range (70 to 

130 percent) for approximately 84 percent of the compounds.
2 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

This study did not attempt to evaluate the quality of 

drinking 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 thresholds 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 nonregulatory health-based thresholds established by the U.S. 

Environmental Protection Agency (USEPA) and CDPH, and 

to non-regulatory thresholds established for aesthetic concerns 

by CDPH. Comparisons between data collected for this study 

and thresholds for drinking water are for illustrative purposes 

only and are not indicative of compliance or noncompliance 

with those thresholds.

Most organic and inorganic constituents that were 

detected in groundwater samples from the 55 grid wells in 

the SCRC study unit were detected at concentrations less 

than drinking-water thresholds. In addition, all detections of 

organic constituents in SCRC grid well samples were less than 

health-based thresholds. 

In total, VOCs were detected in 33 percent of the 55 grid 

wells sampled and pesticides and pesticide degradates were 

detected in 27 percent of grid wells sampled in the SCRC 

study unit. In the Basins study area, VOCs and pesticides 

and pesticide degradates were detected in approximately 

33 percent of the 39 grid wells. In the Uplands study 

area, VOCs were detected in approximately 31 percent 

and pesticides and pesticide degradates were detected in 

approximately 13 percent of the 16 grid wells. 

Trace elements and minor ions were sampled for at 

32 grid wells and nutrients at 33 grid wells in the SCRC 

study unit, and most detections were less than health-based 

thresholds. Exceptions in the Basins study area include 

one detection of arsenic greater than the USEPA maximum 

contaminant level (MCL-US) of 10 μg/L and three detections 

of nitrite plus nitrate, as nitrogen (NO2

-

+NO3

-

) greater than the 

MCL-US of 10 mg/L. Exceptions in the Uplands study area 

include two detections of arsenic greater than the MCL-US 

and eight detections of molybdenum greater than the USEPA 

lifetime health advisory level (HAL-US) of 40 μg/L. All 

detections of major and minor ions and gross alpha and gross 

beta radioactivity from the SCRC grid wells were less than 

health-based thresholds. 

Results for trace elements, major ions, and TDS with 

non-enforceable thresholds set for aesthetic concerns 

from 16 Basins study area grid wells showed that iron 

concentrations greater than the CDPH secondary maximum 

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

in grid wells. Manganese concentrations greater than the 

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

Chloride concentrations greater than the recommended 

SMCL-CA threshold of 250 mg/L were detected in one grid 

well. Sulfate concentrations greater than the recommended 

SMCL-CA threshold of 250 mg/L were measured in 12 grid 

wells and 3 of these wells also were greater than the upper 

SMCL-CA threshold of 500 mg/L. TDS concentrations greater 

than the SMCL-CA recommended threshold of 500 mg/L were 

measured in 14 of the 16 Basins study area grid wells and 

concentrations in 5 of these wells also were greater than the 

SMCL-CA upper threshold of 1,000 mg/L. 

In the Uplands study area, iron concentrations greater 

than the SMCL-CA were detected in 2 of 16 grid wells and 

manganese concentrations greater than the SMCL-CA were 

detected in 3 grid wells. TDS and sulfate concentrations 

greater than the recommended SMCL-CA thresholds were 

detected in 11 and 2 grid wells, respectively, but none of 

these concentrations were greater than the SMCL-CA upper 

thresholds. 

Introduction 

Groundwater comprises about one-half of the water used 

for public and domestic drinking-water supply in California 

(Hutson and others, 2004). 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 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 (http://www.waterboards.

ca.gov/gama). The statewide GAMA program currently 

consists of three Projects: GAMA Priority Basins Project 

conducted by the USGS (http://ca.water.usgs.gov/gama/), 

GAMA Domestic Well Project conducted by the SWRCB, and 

GAMA Special Studies conducted by LLNL. Statewide, the 

GAMA Priority Basins Project primarily focused on the deep 

part of the groundwater resource and the GAMA Domestic 

Well Project generally focused on the shallow aquifer systems. 

All published and quality-assurance/quality-control 

(QA/QC) approved analytical data collected for the 

GAMA program are stored in the web-based Geotracker 

Database (https://geotracker.waterboards.ca.gov/gama/). 

The Geotracker 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 other Regional Boards 

from environmental monitoring wells at contaminated and/or 

remediated sites.
Introduction 3

The SWRCB initiated the GAMA Program in 2000 in 

response to a legislative mandate (Supplemental Report of the 

1999 Budget Act 1999-00 Fiscal Year). The GAMA Priority 

Basins Project was initiated in response to the Groundwater 

Quality Monitoring Act of 2001 (Sections 10780-10782.3 

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

and monitor the quality of groundwater in California. The 

GAMA Priority Basins Project is a comprehensive assessment 

of statewide groundwater quality designed to help better 

understand and identify risks to groundwater resources and 

to increase the availability of information about groundwater 

quality to the public. For the GAMA Priority Basins Project, 

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; State Water Resources Control Board, 2003). 

Additional partners in the GAMA Priority Basins Project 

include LLNL, CDPH, CDWR, CDPR, and local water 

agencies and well owners (Kulongoski and Belitz, 2004). 

Local participation in the project is entirely voluntary.

The GAMA Priority Basins Project is unique in 

California because it includes many chemical analyses that are 

not otherwise available in statewide water-quality monitoring 

datasets. Groundwater samples collected for the project are 

analyzed for approximately 300 chemical constituents using 

analytical methods with lower detection limits than required 

by the CDPH for regulatory monitoring of drinking-water 

wells. These analyses will be especially useful for providing 

an early indication of changes in groundwater quality. In 

addition, the GAMA Priority Basins Project 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 range of hydrologic, geologic, and climatic 

conditions that exist in California must be considered in 

an assessment of groundwater quality. Belitz and others 

(2003) partitioned the State into 10 hydrogeologic provinces, 

each with distinctive hydrologic, geologic, and climatic 

characteristics (fig. 1). All these hydrogeologic provinces 

include groundwater basins and subbasins designated by the 

CDWR (California Department of Water Resources, 2003). 

Groundwater basins and subbasins 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 and subbasins within the 10 hydrologic provinces. 

Groundwater basins and subbasins 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 and subbasins designated by the CDWR, 116 priority 

basins were selected and grouped into 36 study units, 

representing approximately 95 percent of the CDPH wells 

in California. 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. 

Three types of water-quality assessments are 

being conducted with the data collected in each study 

unit: (1) Status: assessment of the current quality of the 

groundwater resource; (2) Trends: detection of changes in 

groundwater quality; and (3) Understanding: identification of 

the natural and human factors affecting 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 systems (hereinafter referred to as primary aquifers) 

are defined as that part of the aquifer corresponding to the 

perforation interval of wells listed in the CDPH database 

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 cities, towns, and mobile-home parks) and transient (such 

as schools, campgrounds, and restaurants). 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 aquifers. 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 VOCs and nitrate) than samples from wells screened 

in the deep primary aquifer (Landon and others, 2010).
4 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Figure 1. The hydrogeologic provinces of California and the location of the South Coast Range–Coastal (SCRC) 

Groundwater Ambient Monitoring and Assessment (GAMA) study unit.

Basin and Range

Central

Valley

Klamath

Mountains

Desert

Cascades and

Modoc Plateau

Transverse Ranges and

selected Peninsular Ranges

Southern Coast

Ranges

Sierra

Nevada

Northern

Coast

Ranges

San Diego

Drainages

South Coast RangeCoastal Study Unit

(figure 2)

Bakersfield

San

Francisco

Sacramento

OREGON

NEVADA

MEXICO

ARIZONA

Redding

Los Angeles

San Diego

PA C I F I C O C E A N

0 200 MILES

0 200 KILOMETERS

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006. 

Albers Equal Area Conic Projection

Provinces from Belitz and others, 2003.
Introduction 5

This data series report is the first in a series of reports 

presenting the water-quality data collected in the Southern 

Coast Range–Coastal study unit and is similar to Data Series 

Reports written for the GAMA study units sampled to date 

(San Diego Drainages Hydrogeologic Province: Wright 

and others, 2005; Northern San Joaquin Basin: Bennett 

and others, 2006; North San Francisco Bay: Kulongoski 

and others, 2006; Southern Sierra: Fram and Belitz, 2007; 

Monterey Bay and Salinas Valley Basins: Kulongoski and 

Belitz, 2007; Southeast San Joaquin Valley: Burton and 

Belitz, 2008; Southern Sacramento Valley: Dawson and 

others, 2008; Central Sierra: Ferrari and others, 2008; San 

Fernando–San Gabriel: Land and Belitz, 2008; Central 

Eastside San Joaquin: Landon and Belitz, 2008; Coastal 

Los Angeles Basin: Mathany and others, 2008; Middle 

Sacramento Valley: Schmitt and others, 2008; Kern County 

Subbasin: Shelton and others, 2008; Northern Sacramento 

Valley: Bennett and others, 2009; Owens and Indian Wells 

Valleys: Densmore and others, 2009; Tahoe–Martis: Fram 

and others, 2009; Coachella Valley: Goldrath and others, 

2009; Upper Santa Ana Watershed: Kent and Belitz, 2009; 

Mojave: Mathany and Belitz, 2009; South Coast Interior 

Basins: Mathany and others, 2009; Santa Clara River Valley: 

Montrella and Belitz, 2009; San Francisco Bay: Ray and 

others, 2009; Madera–Chowchilla: Shelton and others, 2009; 

Colorado River: Goldrath and others, 2010). Subsequent 

reports will address the status, trends, and understanding

aspects of the water-quality assessments of each study unit.

The GAMA Southern Coast Range–Coastal (SCRC) 

study unit (hereinafter referred to as SCRC), contains five 

groundwater basins delineated by CDWR and is located 

along the California coast in the Southern Coast Ranges 

hydrogeologic province. Groundwater is a major source of 

public drinking-water supply for many of the cities located in 

the SCRC (Water Education Foundation, 2006, http://www.

water-ed.org/watersources/default.asp). Therefore, SCRC was 

considered high priority for sampling to provide adequate 

representation of the Southern Coast Ranges hydrogeologic 

province (Belitz and others, 2003). 

Purpose and Scope

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

study design, including the hydrogeologic setting of SCRC 

and the study methods, (2) the results of quality-control 

tests, and (3) the analytical results for groundwater samples 

collected in SCRC. Groundwater samples were analyzed 

for field water-quality indicators, organic and inorganic 

constituents, 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 thresholds considered for this report are 

those established by the U. S. Environmental Protection 

Agency (USEPA) and/or the CDPH. The data presented 

in this report are intended to characterize the quality of 

untreated groundwater in the primary aquifers of the SCRC, 

not the treated drinking water delivered to consumers by 

water purveyors. Discussion of the factors that influence 

the distribution and occurrence of the constituents detected 

in groundwater samples will be the subject of subsequent 

publications.

Hydrogeologic Setting 

The SCRC lies in the southwestern part of the Southern 

Coast Ranges hydrogeologic province as described by 

Belitz and others (2003), and includes five CDWR-defined 

groundwater basins: Los Osos Valley, San Luis Obispo, Santa 

Maria River Valley, San Antonio Creek Valley, and Santa Ynez 

River Valley (California Department of Water Resources, 

2004a,b,c,d,e). The SCRC covers an area of approximately 

766-square-mile (mi2), in Santa Barbara and San Luis Obispo 

Counties, California. The SCRC is bordered on the north by 

the Santa Lucia and San Luis Ranges, on the east by the San 

Rafael Mountains, on the south by the Santa Ynez Mountains, 

and on the west by the Pacific Ocean (fig. 2).

Altitudes in the SCRC range from sea level, where the 

study unit boundary touches the Pacific Ocean, to about 

6,500 feet above sea level, in the San Rafael Mountains. The 

major surface drainage features of the SCRC are the Santa 

Maria and Santa Ynez Rivers and San Antonio Creek and 

their tributaries; all of which terminate in the Pacific Ocean 

(figs 2, 3, 4). 

The climate in the SCRC is influenced in large part 

by the Pacific Ocean and also by the topography of the 

surrounding areas. Areas located along the coastal lowlands 

and/or valleys near the Pacific Ocean have a coastal climate. It 

is characterized by warm dry summers and cool wet winters. 

Coastal fog is common throughout the year (Bright and others, 

1992). Areas in the SCRC located farther from the Pacific 

Ocean, on the slopes of the coastal valleys and/or within 

the upland areas have a Mediterranean climate, with hot dry 

summers and cool wet winters (Hamlin, 1985). Practically 

all precipitation in the SCRC occurs from October through 

April, with average annual precipitation ranging from a low of 

around 13 inches (in.) along the coastal lowlands in the Santa 

Maria River Valley groundwater basin, to more than 20 in. 

in the uplands of the San Luis Obispo groundwater basin 

(California Department of Water Resources, 2004b,c).
6 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Figure 2. The South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study unit showing the 

location and boundaries of the California Department of Water Resources (CDWR) defined groundwater basins, the locations of areas 

outside of the CDWR-defined groundwater basins that are included in the study unit, the location of major cities, topographic features, 

and hydrologic features. 

Sisquoc River

Cuyama River

Santa Ynez River

San Antonio Creek

Santa Maria River

Santa Cruz Creek

Cuyama River

Twitchell

Reservoir

Lake

Cachuma

Barka

Slough

0 5 10 Miles

0 5 10 Kilometers

SANTA BARBARA CO

SAN LUIS OBISPO CO

154

166

1

1

101

101

San Luis Obispo

Pismo Beach

Santa Maria

Lompoc

Solvang

Santa Ynez

PA C I F I C O C E A N

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006. 

Albers Equal Area Conic Projection

San Raphael Mountains

San Luis Range

EXPLANATION

IP008435_Figure 02_GW basins

Los Osos Valley

San Luis Obispo

Santa Maria River Valley

Santa Ynez River Valley

San Antonio Creek Valley

Water bodies

Selected faults

Selected stream or river

Groundwater basins (from California

 Department of Water Resources, CDWR)

Santa Ynez Mountains

Los Osos Fault Zone

Edna Fault Zone

Santa Maria Fault Zone

Santa Lucia Range

Areas outside of the

groundwater basins that

are included in the study unit
Methods 7

Two primary water-bearing formations serve as the 

primary aquifers for all five groundwater basins of the SCRC: 

the Paso Robles Formation and Holocene age alluvial deposits 

of non-marine and fluvial origin. The Pleistocene age Paso 

Robles Formation consists of unconsolidated to poorly 

consolidated coarse sand and gravel, as well as finer sand, 

silt, and clay and some limestone that formed from deposition 

in floodplains and small lakes. The water-bearing units are 

underlain by non-water-bearing Tertiary and Cretaceous 

bedrock and granite (Valentine and others, 2001). The 

Holocene age alluvium consists of unconsolidated gravel, clay, 

silt, and sand of fluvial origin (California Department of Water 

Resources, 2004a,b,c,d,e).

The SCRC was separated into the two study areas 

(Basins and Uplands) by the marine and terrestrial geologic 

formations not common to the five groundwater basins. The 

Basins study area boundaries were defined by the locality 

of the marine sand formations in the Los Osos Valley, Santa 

Maria River Valley, San Antonio Creek Valley, and Santa Ynez 

River Valley groundwater basins (California Department of 

Water Resources, 2004a,c,d,e) (fig. 3). The Uplands study 

area borders were delineated largely by the location of the 

terrace formations in the San Luis Obispo, Santa Maria River 

Valley, San Antonio Creek Valley, and Santa Ynez River 

Valley groundwater basins and a large part of the uplands near 

the city of Pismo Beach, located just north of the Santa Maria 

Valley groundwater basin (California Department of Water 

Resources, 2004b,c,d,e). The Uplands study area also included 

uplifted areas just outside of the eastern Santa Maria Valley, 

southern San Antonio Creek Valley, and eastern Santa Ynez 

River Valley groundwater basins (fig. 3).

The geologic formations that were used to categorize 

the Basins study area are the Careaga Sand formation and 

unnamed dune sand formations. The Careaga Sand formation 

is of Pliocene age and is made up of unconsolidated fine to 

medium grained marine sand and occurs in the Los Osos 

Valley, Santa Maria River Valley, San Antonio Creek Valley, 

and Santa Ynez River Valley groundwater basins (California 

Department of Water Resources, 2004a,c,d,e). Dune sand 

formations of Pleistocene age occur in the Los Osos Valley 

and San Antonio Creek Valley groundwater basins and dune 

sand of Holocene and Pleistocene age are present in the Santa 

Maria Valley groundwater basin (California Department of 

Water Resources, 2004a,c,d). 

The geologic formations that were used to categorize 

the Uplands study area are the alluvial terrace deposits and 

the Orcutt Formation. The alluvial terrace deposits are of 

Pleistocene age, and consist of unconsolidated sand, gravel, 

silt, and clay, and located in the San Luis Obispo and the Santa 

Ynez River Valley groundwater basins and in the uplands 

located just outside of the Santa Maria Valley groundwater 

basin (California Department of Water Resources, 2004b,c,e). 

The Pleistocene age Orcutt Formation, which may be 

classified as a terrace deposit, consists of unconsolidated clay 

and sand interbedded with gravel and primarily of fluvial 

origin (California Department of Water Resources, 2004c,d,e). 

The SCRC has three major faults zones (the Los Osos, 

Edna, and Santa Maria River), each acting as a barrier to the 

lateral movement of groundwater (California Department 

of Water Resources, 2004a,b,c,d) (fig. 2). There also is a 

subsurface restrictive structure within the San Antonio Creek 

Valley groundwater basin that creates the wetland known as 

Barka Slough (California Department of Water Resources, 

2004c) (fig. 2). 

Groundwater recharge in the SCRC occurs from a 

mixture of ambient recharge (percolation of precipitation, 

irrigation waters, and seepage from streams and rivers), 

subsurface inflow, and engineered recharge (urban and 

agricultural return-water, treated wastewater, and lakes) 

(California Department of Water Resources, 2004a,b,c,d,e).

Methods 

Methods used for the GAMA Priority Basins Project 

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 quality-assurance plan, and the results 

of analyses of quality-control samples.

Study Design

The wells selected for sampling in this study reflect 

the combination of two well-selection strategies. Fiftyfive “grid” wells were selected to provide a statistically 

unbiased, spatially distributed assessment of the quality of 

groundwater resources used for public drinking-water supply, 

while 15 additional “understanding” wells were selected to 

provide greater sampling density in several areas to aid in 

understanding of specific groundwater quality issues in the 

study unit.

The spatially distributed wells were selected using a 

randomized grid-based method (Scott, 1990). The randomized 

grid-based method divides the study unit into equal area grid 

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

divided into multiple pieces in order 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 one grid cell. The objective for the 

SCRC study was to sample at least one public-supply well per 

grid cell. 
8 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Figure 3. The South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study unit showing the 

boundaries of the Basins and Uplands study areas, the location of public-supply wells with a record in the California Department of 

Public Health (CDPH) Database, major cities, major roads, topographic features, and hydrologic features.

Sisquoc River

Cuyama River

Santa Ynez River

San Antonio Creek

Santa Maria River

Santa Cruz Creek

Cuyama River

Twitchell

Reservoir

Lake

Cachuma

Barka

Slough

SANTA BARBARA CO

SAN LUIS OBISPO CO

154

166

1

1

101

101

San Luis Obispo

Pismo Beach

Santa Maria

Lompoc

Solvang

Santa Ynez

Basins

(Marine sand and dune sand deposits)

Uplands

(Alluvial terrace deposits)

Study area

IP008435_Figure 3

0 5 10 Miles

0 5 10 Kilometers

PA C I F I C O C E A N

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006. 

Albers Equal Area Conic Projection

San Raphael Mountains

Santa Lucia Range

EXPLANATION

San Luis Range

Santa Ynez Mountains

Geology from Saucedo and others, 2000.

Public-supply well—With a record in California

 Department of Public Health (CDPH) Database
Methods 9

The Basins study area was divided into 45 equal area 

grid cells, approximately 10 mi2 (25 square-kilometers 

[km2]) in area, with a total of 39 wells sampled within this 

grid network (fig. 4). Relatively few public-supply wells 

were in the Uplands study area, and these wells were not 

evenly distributed. To minimize the number of cells without 

any wells, only the part of the Uplands study area in close 

proximity to a public-supply well was included in the gridded 

area. Locations of public-supply wells listed in the statewide 

database maintained by the CDPH were plotted and 1.86-

mi (3-km) radius circles were drawn around each well. The 

collective area encompassed by the circles was initally divided 

into fourteen 10-mi2 grid cells (fig. 4). Two additional wells 

that were not public-supply wells, but which had similar 

construction characteristics, were sampled in the Uplands 

study area outside of the original grid network to expand the 

spatial distribution, resulting in a total of 16 wells. A 1.86-mi 

(3-km) radius circle was drawn around each of the additional 

wells to increase the size of the Uplands study area from 

140 mi2 to 160 mi2.

In the SCRC, an attempt was made to sample available 

public-supply wells located within each grid cell. If a grid 

cell contained more than one public-supply well, each well 

randomly was assigned a rank. The highest ranking well that 

met basic sampling criteria (for example, sampling point 

located prior to treatment or capability to pump for several 

hours), and for which permission to sample could be obtained, 

was sampled. If a grid cell contained no accessible publicsupply wells, then other types of wells, such as irrigation, 

environmental monitoring, industrial, and/or domestic wells, 

were considered for sampling. An attempt was made to select 

“alternative” wells with depths and screened intervals similar 

to those in public-supply wells in the area. In this fashion, 

one well was selected in each cell to provide a spatially 

distributed, randomized monitoring network. 

The land use in the SCRC is predominantly classified 

as agricultural, and the locations of the public-supply wells 

tend to be clustered around the more urbanized areas of the 

study unit (Volgelmann and others, 2001; Price and others, 

2003) (fig. 3). As a result, there were more irrigation wells 

than public-supply wells available and sampled within the 

time-frame of the spatially distributed, randomized grid-based 

assessment of the primary aquifers in the SCRC. 

Wells sampled as part of the spatially distributed, 

randomized grid-cell network are hereinafter referred to as 

“grid wells”. The 55 grid wells sampled in SCRC were named 

for the study area where they were located by using the prefix 

“SCRC-B” for the Basins study area and “SCRC-H” for the 

Uplands study area and by using a suffix numbered in the 

order of sample collection within each study area (fig. 4).

Fifteen additional, non-randomized wells (hereinafter 

referred to as “understanding wells”) were sampled in the 

SCRC to collect more information for specific water-quality 

issues within the study unit. Wells sampled as part of these 

studies were not included in the statistical characterization of 

water quality in SCRC because inclusion of these wells would 

lead to the overrepresentation of some cells. These additional, 

non-randomized wells were named by using the prefix 

“SCRC-U” (“U” indicating “understanding”) and by using a 

suffix numbered in the order of sample collection (fig. 4).

In addition, three surface-water samples were collected in 

the Basins study area in streams near the location of two of the 

sampled wells (SCRC-B30 and SCRC-U05) in order to better 

comprehend the interaction between groundwater and surface 

water in the area. The surface-water samples were named 

by using the prefix “SCRC-SW” (“SW” indicating “surface 

water”) and by using a suffix numbered in the order of sample 

collection (fig. 4).

The GAMA alphanumeric identification number for 

each well and surface-water site, along with the date sampled, 

sampling schedule, well and surface-water site altitude, well 

type, and available well-construction information is shown in 

table 1) (all tables at back of report). Groundwater samples 

were collected from 31 irrigation wells, 23 public-supply 

wells, 8 environmental monitoring wells, 5 industrial wells, 

and 3 domestic wells during the period from May to December 

2008. 

Well locations and identifications were verified using 

global positioning system (GPS), 1:24,000-scale USGS 

topographic maps, comparison with existing well information 

in USGS and CDPH Databases, and information provided 

by well owners. Drillers’ logs for wells were obtained when 

available. Well information was recorded by hand on field 

sheets, and electronically on field laptop computers using 

the portable computer field forms (PCFF) program designed 

for USGS sampling. All information was verified and then 

uploaded into the USGS National Water Information System 

(NWIS). Well owner and well type information is confidential.

The wells in SCRC were sampled using a tiered 

analytical approach. All wells were sampled for a standard 

set of constituents, including volatile organic compounds 

(VOCs), 1,2,3-TCP, pesticides and pesticide degradates, polar 

pesticides and metabolites, perchlorate, stable isotopes of 

hydrogen and oxygen in water, tritium, and dissolved noble 

gases. The standard set of constituents was termed the “fast” 

schedule (table 2). Wells on the “slow” schedule were sampled 

for all constituents on the fast schedule, plus pharmaceuticals, 

N-nitrosodimethylamine (NDMA), trace elements, nutrients, 

dissolved organic carbon (DOC), major and minor ions, 

silica, total dissolved solids (TDS), alkalinity, arsenic and 

iron speciation, gross alpha and gross beta radioactivity, 

stable isotopes of carbon in dissolved inorganic carbon and 

carbon-14 abundance (table 2). In addition, some fast and 

slow wells were included on a “special study” schedule 

and sampled for stable isotopes of nitrogen and oxygen in 

dissolved nitrate, stable isotopes of sulfur in dissolved sulfate, 

and dissolved gases (table 2). The “surface-water” schedule 

consisted of trace elements, nutrients, major and minor 

ions, silica, TDS, alkalinity, stable isotopes of hydrogen and 

oxygen in water, and stable isotopes of nitrogen and oxygen in 

dissolved nitrate (table 2).
10 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Figure 4. The South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study unit showing the 

distribution of the Basins and Uplands study area-grid cells, the location of sampled grid and understanding wells and surface-water 

sites, major cities, major roads, topographic features, and hydrologic features.

Sisquoc River

Cuyama River

Santa Ynez River

San Antonio Creek

Santa Maria River

Santa Cruz Creek

Cuyama River

Twitchell

Reservoir

Lake

Cachuma

Barka

Slough

SANTA BARBARA CO

SAN LUIS OBISPO CO

154

166

1

1

101

101

0 5 10 Miles

0 5 10 Kilometers

San Luis Obispo

Pismo Beach

Santa Maria

Lompoc

Solvang

Santa Ynez

H14

H11

H01

B04

B02

B01

B18 B32

B25

B22

B17

B16

B15

B39

B31

U04

U04

B29 B28

U06

B23 B27 U05

SW2

SW2

SW3

SW1 B30

U08

B36 U10

U09

U07

B20

B19 B05 B14

B03

B24 B38

B06

H13 U13 H06

U15

U14

H07

U03

B34

U12

U11 B35

B11

B21 U02

B37 B26 U01

H16

B12

B13

B09

B08

H03

B33 H04

H08

H05

H02

H09 B10

B07 H12

H10

H15

B18

Basins study area

 grid cell 

Uplands study area

 grid cell 

SCRC grid well and identifier

SCRC understanding well and identifier

SCRC surface-water

 sampling site and identifier

Study areas

IP008435_Figure 4

PA C I F I C O C E A N

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006. 

Albers Equal Area Conic Projection

San Raphael Mountains

Santa Lucia Range

EXPLANATION

San Luis Range

Santa Ynez Mountains

Basins

Uplands

"SCRC" identifier has been omitted from

 figure due to spatial concerns

Geology from Saucedo and others, 2000.
Water-Quality Results 11

Fast and slow refer to the time required to sample the 

well for all analytes on the respective schedules. Two slow or 

three fast wells generally could be sampled in 1 day. In SCRC, 

29 of the wells were sampled on the fast schedule (22 grid and 

7 understanding), 29 wells were sampled on the slow schedule 

(27 grid and 2 understanding), 12 wells were sampled on 

the fast or slow plus special study schedule (6 grid and 6 

understanding), and 3 sites were sampled on the surface-water

schedule (table 1).

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 ensure that representative 

samples of groundwater are collected at each site and that the 

samples are collected and handled in ways that minimize the 

potential for contamination. 

Tables 3A–K list the compounds analyzed in each 

constituent class. Groundwater samples were analyzed for 

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

(table 3B); 60 polar pesticides and metabolites (table 3C); 

14 pharmaceutical compounds (table 3D); 3 constituents 

of special interest (table 3E); 25 trace elements (table 3F); 

9 nutrients and DOC (table 3G); 9 major and minor ions, 

silica, TDS, and alkalinity (table 3H); arsenic and iron species 

(table 3I); stable isotopes of hydrogen and oxygen in water, 

stable isotopes of nitrogen and oxygen in dissolved nitrate, 

stable isotopes of sulfur in dissolved sulfate, stable isotopes 

of carbon in dissolved inorganic carbon, and 4 radioactive 

constituents, including tritium and carbon-14 abundance 

(table 3J); 10 dissolved gases (including noble gases), tritium, 

and helium stable isotopic ratios (table 3K). The methods 

used for sample collection and analysis are described in the 

appendix section titled “Sample Collection and Analysis.”

Data Reporting

The methods and conventions used for reporting the 

data are described in the appendix section titled “Data 

Reporting.” Twelve constituents analyzed in this study were 

measured by more than one analytical schedule or more than 

one laboratory. Four constituents analyzed in this study were 

measured by more than one method at the USGS National 

Water Quality Laboratory (NWQL), but only the results from 

the preferred method are reported (see the appendix section 

titled “Constituents on Multiple Analytical Schedules”). 

One constituent (metalaxyl) was measured by two analytical 

schedules at the NWQL and data from both methods are 

presented. Three constituents—1,2,3-TCP, arsenic, and iron 

concentrations—were measured by two different laboratories 

and both sets of results are reported for these constituents. 

Tritium activities were measured by two different laboratories 

but only one set of results are presented in this report.

Quality Assurance

The quality-assurance and quality-control 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 quality-assurance plan followed by 

the USGS National Water Quality Laboratory (NWQL), 

the primary laboratory used to analyze samples for this 

study, is described in Pirkey and Glodt (1998) and Maloney 

(2005). Quality-control (QC) samples collected in the SCRC 

study include: blanks, replicates, and matrix and surrogate 

spikes. 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. Quality-control 

procedures and quality-control sample results are described in 

the appendix section titled “Quality Assurance.”

Water-Quality Results 

Quality-Control Results

Results of quality-control 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 blanks collected for this and previous 

GAMA Priority Basins Project study units, some detections 

reported by the laboratory for three organic compounds were 

considered suspect and, therefore, were removed from the 

set of groundwater-quality data presented in this report (see 

table A3 and additional discussion in the appendix). Results 

from the replicates confirm that the procedures used to collect 

and analyze the samples were consistent. Variability for nearly 

100 percent of the replicate pairs for constituents detected in 

samples was within the acceptable limits of 10 percent relative 

and/or standard deviation (tables A4A–C). Median matrixspike recoveries for 33 of the 211 organic and special interest 

constituents analyzed were lower than the acceptable limit of 

70 percent (tables 3B, 3C, A5B, and A5C), which may indicate 

that these constituents might not have been detected in some 

samples if they were present in the samples at concentrations 

near the laboratory reporting levels (LRLs). The qualitycontrol results are described in the appendix section titled 

“Quality-Control Results.”
12 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Comparison Thresholds

Concentrations of constituents detected in groundwater 

samples were compared with CDPH and USEPA regulatory 

and non-regulatory drinking-water health-based thresholds 

and thresholds established for aesthetic purposes (California 

Department of Public Health, 2008a,b; U.S. Environmental 

Protection Agency, 2008a,b). The chemical data presented 

in this report are meant to characterize the quality of the 

untreated groundwater within the primary aquifers of SCRC 

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 

thresholds are for illustrative purposes only and are not 

indicative of compliance or noncompliance with drinkingwater regulations. The following thresholds 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. CDPH has established MCLs for additional 

constituents not regulated by the USEPA, as well as 

lowered the threshold concentration for a number of 

constituents with MCLs established by the USEPA. In 

this report, a threshold set by the USEPA and adopted 

by CDPH is labeled “MCL-US”, and one set by CDPH 

that is more stringent than the MCL-US is labeled 

“MCL-CA”. CDPH is notified when constituents are 

detected at concentrations greater than an MCL-US 

or MCL-CA thresholds in samples collected for the 

GAMA Priority Basins Project, but these detections do 

not constitute violations of CDPH regulations.

• 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 thresholds 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 thresholds are labeled “AL-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 CDPH are not required to be 

at least as stringent as those established by USEPA. 

SMCLs established by 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 (NLCA). 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 L (2.1 quarts) of 

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

(154-lb) 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 cancer 

risk concentration established by the USEPA by 10 

(RSD5-US).

For constituents with MCLs, detections in groundwater 

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

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 for these 

constituents corresponds to the recommended SMCL-CA. 

Detected concentrations of constituents that lack an MCL or 

SMCL were compared to the NL-CA. For constituents that 

lack an MCL, SMCL, or NL-CA, detected concentrations 

were compared with the HAL-US. For constituents that 

lack an MCL, SMCL, NL-CA, or HAL-US, detected 

concentrations were compared with the RSD5-US. Note 
Water-Quality Results 13

that if a constituent has more than one type of established 

threshold, using this hierarchy to select the comparison 

threshold will not necessarily result in selection of the 

threshold with the lowest concentration. For example, zinc has 

an SMCL-CA of 5,000 μg/L and a HAL-US of 2,000 μg/L, 

and the comparison threshold selected by this hierarchy 

is the SMCL-CA. The comparison thresholds used in this 

report are listed in tables 3A–K for all constituents and in 

tables 4–14 for constituents detected in groundwater samples 

from SCRC. Not all constituents analyzed for this study have 

established thresholds available. Detections of constituents at 

concentrations greater than the selected comparison threshold 

are marked with asterisks in tables 4, 5, 8–11, and 13. 

Groundwater-Quality Data

Results from analyses of untreated groundwater 

samples from SCRC are presented in tables 4–14. These 

results are separated into the two study areas that make up 

the SCRC (Basins grid wells and Uplands grid wells), the 

understanding well samples, and the surface-water samples. 

Groundwater samples collected in SCRC were analyzed for 

298 constituents; 181 of those constituents were not detected 

in any of the samples, 96 constituents were detected, and 

results for 21 constituents have not been received or are being 

evaluated and are not presented in this report (tables 3A–K). 

For organic and special interest (perchlorate) constituent 

classes that were analyzed at all grid wells, the results tables 

include the following summary statistics for all 55 SCRC 

grid wells and for the grid wells in each study area (Basins 

and Uplands): the number of wells at which each analyte 

was detected, the frequency at which it was detected (in 

relation to the number of grid wells in the study area), and 

the total number of constituents detected at each well. For 

the inorganic, isotopic, and radioactive constituent classes, 

the summary tables include all wells, constituents, and 

samples analyzed. Results from the understanding wells are 

presented in the tables, but these results were excluded from 

the detection frequency calculations to avoid statistically 

over-representing the areas near the understanding wells. The 

surface-water sample results are presented in tables 4, 8, 9, 10, 

and 12. 

Field water-quality indicators measured in the field and at 

the NWQL are included in table 4. The results of groundwater 

and/or surface-water analyses organized by compound classes 

are presented in tables 5–14: 

• Organic constituents

• Volatile organic compounds (VOC) (table 5)

• Pesticides and pesticide degradates (table 6A)

• Polar pesticides and metabolites (table 6B)

• Perchlorate (table 7)

• Inorganic constituents

• Trace elements (table 8)

• Nutrients and dissolved organic carbon (DOC) 

(table 9)

• Major and minor ions, silica, and total dissolved 

solids (TDS) (table 10)

• Arsenic and iron speciation (table 11)

• Isotopic tracers (table 12)

• Dissolved gases (table 13)

• Radioactive constituents (table 14)

Results for pharmaceutical compounds are not 

presented in this report; they will be included in a subsequent 

publication. In addition, as of the publishing date of this 

data report, the results of analyses of samples collected in 

SCRC for the stable-isotope ratios of sulfur in dissolved 

sulfate, dissolved noble gases, and helium isotope ratios 

were not available; results will be presented in a subsequent 

publication.

Field Water-Quality Indicators 

Field and laboratory measurements of dissolved oxygen, 

pH, specific conductance, alkalinity, and associated parameters 

(turbidity, water temperature, and bicarbonate and carbonate 

concentrations) are presented in table 4. Alkalinity, dissolved 

oxygen, and bicarbonate and carbonate concentrations are 

used as indicators of natural processes that affect water 

chemistry. Specific conductance is the measure of electrical 

conductivity of the water and is proportional to amount of 

total dissolved solids in the water. The pH value indicates the 

acidity of the water. 

Field specific-conductance values for 69 percent of SCRC 

grid wells (38 of 55 wells: 30 of 39 Basins grid wells and 8 of 

16 Uplands grid wells) were greater than the recommended 

SMCL-CA of 900 μS/cm. Field specific-conductance values 

for six of the Basins grid wells also were greater than the 

upper threshold of 1,600 μS/cm. 

Field specific-conductance values for 10 of the 15 

understanding wells were greater than the recommended 

SMCL-CA. In addition, values for 7 of the 10 understanding 

wells and all surface-water samples were greater than the 

SMCL-CA upper threshold. 

Field pH values for 2 of the 55 grid wells sampled 

(2 Basins grid wells) in the SCRC were outside of the 

SMCL-US range for pH. Field pH values for 3 of the 15 

understanding wells were outside of the SMCL-US range 

(table 4). (Laboratory pH values may be dissimilar to field 

pH values because the pH of groundwater may change upon 

removal from the ambient environment and exposure to the 

atmosphere.)
14 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Field turbidity values for all three surface-water samples 

were greater than the recommended SMCL-CA threshold of 

5 NTRUs (table 4).

Organic Constituents

Volatile organic compounds (VOC) may be 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, 14 were detected in SCRC 

groundwater samples; all detections in grid well samples 

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

more VOCs were detected in 18 of the 55 SCRC grid wells 

(about 33 percent detection frequency) sampled. In the 

Basins study area, VOCs were detected in approximately 

33 percent of the 39 grid wells. VOCs that were detected 

in more than 10 percent of the Basins study area grid wells 

were chloroform (trichloromethane), perchloroethene (PCE, 

tetrachloroethene), dichlorodifluoromethane (CFC-12), and 

trichlorofluoromethane (CFC-11). In the Uplands study area, 

VOCs were detected in approximately 31 percent of the 

16 grid wells. Chloroform (trichloromethane) was the only 

VOC detected in more than 10 percent of the Uplands study 

area grid wells. One or more VOCs were detected in 2 of the 

15 understanding wells in the SCRC. Cis-1,2-dichloroethene 

(cis-1,2-DCE) and vinyl chloride (chloroethene) were detected 

at concentrations greater than the corresponding MCL-CA in 

one understanding well (table 5). 

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 at 

69 wells (54 grid and 15 understanding) in the SCRC study, 

11 pesticides were detected in groundwater samples; all 

detections were well below health-based thresholds (table 6A). 

One or more pesticide compounds were detected in 15 of the 

54 SCRC grid wells (about 28 percent detection frequency) 

sampled. In the Basins study area, pesticides and pesticide 

degradates were detected in approximately 34 percent of the 

38 grid wells. The herbicides atrazine and deethylatrazine (a 

degradate of atrazine) were detected in more than 10 percent 

of the Basins grid well samples. Atrazine and deethylatrazine 

are among the Nation’s most commonly detected pesticide 

compounds in groundwater (Gilliom and others, 2006). In the 

Uplands study area, pesticides and pesticide degradates were 

detected in approximately 13 percent of the 16 grid wells. No 

pesticide and pesticide degradate was detected in more than 

10 percent of the grid well samples in the Uplands study area. 

One or more pesticide compounds were detected in 5 of the 

15 understanding wells sampled (table 6A). 

In addition, groundwater samples for 60 polar pesticides 

and metabolites were analyzed at 69 wells (54 grid and 

15 understanding) in the SCRC study. Four polar pesticides 

and metabolites were detected and all detections were well 

below health-based thresholds (table 6B). In the Basins study 

area, polar pesticides and metabolites were detected in 3 of 

the 38 grid wells sampled. No polar pesticide and metabolites 

were detected in any of the 16 grid wells in the Uplands study 

area. One polar pesticide and one metabolite were detected in 

a single understanding well sample (table 6B). 

Constituents of Special Interest

Perchlorate, NDMA, and 1,2,3-TCP are constituents 

of special interest in California because they may adversely 

affect water quality and recently have been detected in water 

supplies (California Department of Public Health, 2008b). 

Perchlorate was analyzed for at all 70 wells in SCRC and 

was detected in 60 percent of the grid wells (33 of 55 wells: 

28 of 39 Basin grid wells and 5 of 16 Upland grid wells). 

Perchlorate was not measured at concentrations greater than 

the MCL–CA in any of the grid or understanding wells in 

SCRC (table 7). 1,2,3-TCP was sampled for at all 70 wells 

and NDMA at the 39 slow wells in the SCRC, and both 

analytes were not detected in any wells. As a result, NDMA 

and 1,2,3-TCP are not included in table 7. 

Inorganic Constituents

Unlike the organic constituents and the constituents 

of special interest, most of the inorganic constituents are 

naturally present in groundwater, although their concentrations 

may be influenced by human activities. Inorganic constituents 

were sampled on the slow sampling schedule (32 grid and 

7 understanding wells) in SCRC, and trace elements, nutrients, 

major and minor ions, silica, TDS, and alkalinity were 

sampled for on the surface-water schedule. Three additional 

nutrient samples were collected at the special study wells, 

coinciding with collection of samples analyzed for stable 

isotopes of nitrogen and oxygen in dissolved nitrate from these 

wells. 

Twenty-two of 25 trace elements analyzed in this study 

have regulatory health-based or non-regulatory aesthetic 

thresholds (table 3F). Of the 18 trace elements with healthbased thresholds, concentrations of most detections of the 

trace elements in the SCRC grid wells were less than these 

thresholds (table 8). The exceptions were a few detections of 

arsenic and molybdenum greater than thresholds. An arsenic 

concentration greater than the USEPA maximum contaminant 

level (MCL-US) of 10 μg/L was detected in 1 of the 16 basins 

grid well samples analyzed for trace elements. Arsenic 

concentrations greater than the MCL-US were detected in 

2 of the 16 Uplands grid wells analyzed for trace elements. 

Molybdenum concentrations greater than the USEPA lifetime 

health advisory level (HAL-US) of 40 μg/L were detected in 

eight Uplands grid wells (table 8). 
Water-Quality Results 15

Trace elements were sampled for at seven slow

understanding wells in SCRC. Molybdenum concentrations 

greater than the HAL-US threshold were detected in one 

understanding well (table 8).

Nutrients (nitrogen and phosphorus) and dissolved 

organic carbon (DOC) 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 can adversely affect human health, 

particularly the health of infants. 

Concentrations of ammonia, nitrate, nitrite, and 

phosphorus measured in samples from 17 grid wells in the 

Basins study area and 16 grid wells in the Uplands study area 

were mostly less than health-based thresholds. Nitrite plus 

nitrate, as nitrogen (NO2

–+NO3–) concentrations greater than 

the MCL-US of 10 mg/L were detected in three Basins grid 

wells (table 9). Detections of NO2

–+NO3– greater than the 

MCL-US also occurred in three of nine understanding wells, 

and all three surface-water samples in SCRC (table 9). 

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. CDPH has established non-enforceable 

thresholds (SMCL-CA) that are based on aesthetic properties 

rather than on human-health concerns for several trace 

elements, the ions chloride and 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, manganese, TDS, chloride, and sulfate were 

sampled for at 16 grid wells in the Basins study area, 16 grid 

wells in the Uplands study area, 7 understanding wells, and 

the three surface-water sites in the SCRC.

Iron concentrations greater than the SMCL-CA of 

300 μg/L were detected in three Basins and two Uplands study 

area grid wells (table 8). 

Manganese concentrations greater than the SMCL-CA 

of 50 μg/L were detected in nine grid wells; these detections 

occurred in six grid wells in the Basins study area and three 

grid wells in the Uplands study area. In the SCRC, manganese 

concentrations greater than the SMCL-CA were detected in 

one of seven understanding wells (table 8).

Chloride concentrations greater than the recommended 

SMCL-CA threshold of 250 mg/L were detected in one Basins 

grid well (table 10).

Sulfate concentrations greater than the recommended 

SMCL-CA threshold of 250 mg/L were detected in 14 grid 

well samples in SCRC, including 12 Basin grid wells and 

2 Uplands grid wells (table 10). Sulfate concentrations 

greater than the upper SMCL-CA threshold of 500 mg/L 

were detected in 3 Basins grid wells (table 10). Sulfate 

concentrations greater than the recommended SMCL-CA 

threshold of 250 mg/L were detected in four understanding 

wells and all three surface-water samples. Sulfate 

concentrations greater than the upper SMCL-CA threshold of 

500 mg/L were detected in one of three surface-water samples 

(table 10).

 TDS concentrations greater than the recommended 

SMCL-CA threshold of 500 mg/L were detected in 25 grid 

wells, including 14 Basins grid wells and 11 Uplands grid 

wells (table 10). TDS concentrations greater than the upper 

SMCL-CA threshold of 1,000 mg/L were detected in 5 of 

14 Basins grid wells. TDS concentrations greater than the 

upper SMCL-CA were detected in four SCRC understanding 

wells and all three surface-water samples (table 10). 

Arsenic and iron occur in 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 oxidation–

reduction state of the aquifer. Concentrations of total arsenic 

and iron and the concentration of either the reduced or the 

oxidized species of each element are reported in table 11. 

The concentration of the other species can be calculated by 

difference. The concentrations of arsenic and iron reported 

in table 11 may be different than those reported in table 8

because different analytical methods were used (see the 

appendix section titled “Constituents on Multiple Analytical 

Schedules”). The concentrations reported in table 8 are 

considered to be more accurate. Some of the arsenic and iron 

species analyses were not completed in time for inclusion in 

this report; complete results will be presented in a subsequent 

publication.

Isotopic Tracers and Dissolved Gases

The isotopic ratios of hydrogen and oxygen in water, 

nitrogen and oxygen in dissolved nitrate, sulfur in dissolved 

sulfate, and carbon in dissolved inorganic carbon, tritium 

activity, carbon-14 abundance, and the concentrations of 

dissolved gases (including noble gases) may be used as tracers 

of hydrologic processes (Clark and Fritz, 1997). 

The isotopic ratios of hydrogen and oxygen in 

water (table 12) 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. 
16 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Stable-isotope ratios of sulfur in dissolved sulfate can be 

used to aid in the characterization of the groundwater system 

by determining the source of dissolved sulfur species and/or 

understanding chemical reactions occurring in groundwater 

systems, such as the microbial reduction of sulfate or the 

oxidation of sulfide. Measurements of isotopic ratios of sulfur 

in dissolved sulfate were not completed in time for inclusion 

in this report; results will be presented in a subsequent 

publication.

Stable-isotope ratios of nitrogen and oxygen in dissolved 

nitrate (table 12) can be used to aid in interpretation of sources 

and processes affecting this solute in aquifers. 

Tritium activities (table 12), helium isotope ratios, and 

carbon-14 abundance (table 12) 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 atmospheric testing of nuclear weapons 

between 1952 and 1963. Thus, concentrations of tritium above 

background generally indicate the presence of water recharged 

since 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 (table 12) 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 incorporated into atmospheric carbon dioxide. Carbon 

dioxide dissolves in precipitation, surface water, and 

groundwater exposed to the atmosphere, thereby entering the 

hydrologic cycle. Because carbon-14 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 thousand years old. 

Concentrations of dissolved gases (including noble 

gases) are used to estimate the conditions of groundwater 

recharge, particularly the temperature of the recharge water. 

Dissolved gases (including noble gases) dissolve in water 

that is in contact with the atmosphere, and the solubilities 

of the different gas species vary with temperature. Results 

for analyses of dissolved gases are presented in table 13. 

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 threshold. All 

measured tritium activities in samples from SCRC wells were 

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

threshold (table 12).

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. Both uranium and thorium decay in a series of steps 

eventually forming stable isotopes of lead (Soddy, 1913; Faure 

and Mensing, 2005). In each step in the decay series, one 

radioactive element turns into a different radioactive element 

by emitting an alpha or a beta particle from its nucleus. The 

alpha and beta particles emitted during radioactive decay are 

hazardous to human health because these energetic particles 

may damage cell DNA and may increase the risk of getting 

cancer.

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 is approximately 

equal to two atoms decaying per minute. The number of atoms 

decaying is equal to the number of alpha or beta particles 

emitted. 

 The 39 slow samples in SCRC were analyzed for gross 

alpha and gross beta radioactivity. Activities for all samples 

from the 32 grid wells were less than established health-based 

thresholds. Activities of gross alpha radioactivity (72-hour 

count) greater than the MCL-US of 15 pCi/L were measured 

in one understanding well (of seven) (table 14). Five of the 

radioactive analytes (three gross alpha and two gross beta, 

72-hour counts) were counted after the 72-hour time period 

at the laboratory. A delay in the counting by the laboratory 

may result in lower activities than may have been observed 

for these analytes if the count had been preformed within the 

72-hour time period; the results for these five analytes are 

footnoted in table 14.

Future Work

Subsequent reports will be focused on assessment of 

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

qualitative, and quantitative approaches to evaluate the natural 

and human factors affecting groundwater quality in SCRC. 

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.
Summary 17

Summary 

Groundwater quality in the approximately 766-squaremile South Coast Range–Coastal (SCRC) study unit was 

investigated from May to December 2008, as part of 

the Priority Basins Project of the Groundwater Ambient 

Monitoring and Assessment (GAMA) Program. The 

GAMA Priority Basins Project was developed in response 

to Legislative mandates (Supplemental Report of the 1999 

Budget Act 1999-00 Fiscal Year; and, the GroundwaterQuality Monitoring Act of 2001 [Sections 10780-10782.3 

of the California Water Code, Assembly Bill 599]) to assess 

and monitor the quality of groundwater in California and 

is being conducted by the U.S. Geological Survey (USGS) 

in cooperation with the California State Water Resources 

Control Board (SWRCB). The SCRC study unit was the 25th

study unit to be sampled as part of the GAMA Priority Basins 

Project.

The GAMA SCRC study unit was designed to provide 

a spatially unbiased assessment of untreated groundwater 

quality in the primary aquifer systems and to facilitate 

statistically consistent comparisons of untreated groundwater 

quality throughout California. The primary aquifer systems 

(hereinafter referred to as primary aquifers) are defined as 

as that part of the aquifer corresponding to the perforation 

interval of wells listed in the California Department of Public 

Health (CDPH) database for the SCRC study unit. The quality 

of groundwater in shallow or deep water-bearing zones may 

differ from that in the primary aquifers; shallow groundwater 

may be more vulnerable to surficial contamination.

The SCRC study unit is located in the southwestern part 

of the South Coast Ranges hydrologic province and includes 

five groundwater basins defined by the California Department 

of Water Resources. The SCRC study unit included 

assessment of the groundwater quality from 70 wells in Santa 

Barbara and San Luis Obispo Counties, California. Fifty-five 

of the wells were selected using a randomized grid approach 

to achieve statistically unbiased representation of groundwater 

used for public drinking-water supplies. Fifteen of the wells 

were selected to provide additional sampling density to aid 

in understanding processes affecting groundwater quality. In 

addition to the 70 wells sampled, 3 surface-water samples 

were collected in streams near 2 of the sampled wells in order 

to better comprehend the interaction between groundwater and 

surface water in the area.

Groundwater samples were analyzed for field waterquality indicators, organic and special interest constituents, 

naturally occurring inorganic constituents, and radioactive 

constituents. Naturally occurring isotopes and dissolved gases 

(including 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 total, 298 constituents and 

field water-quality indicators were investigated for this study. 

This report describes the sampling, analytical, and qualityassurance methods used in the study and presents the results of 

the chemical analyses of the groundwater samples.

This study did not attempt to evaluate the quality of 

drinking 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 thresholds 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 non-regulatory health-based 

thresholds established by the U.S. Environmental Protection 

Agency (USEPA) and CDPH and non-regulatory thresholds 

established for aesthetic concerns by CDPH.

All detections of organic constituents in samples from the 

55 SCRC grid wells were less than health-based thresholds. 

In addition, all detections of organic constituents in samples 

from the 15 understanding wells were less than healthbased thresholds with the exception of the volatile organic 

compounds (VOC) cis-1,2-dichloroethene (cis-1,2-DCE) 

and vinyl chloride (chloroethene) detected at concentrations 

greater than the corresponding CDPH maximum contaminant 

level (MCL-CA) in one understanding well.

Results from SCRC grid wells showed that most 

detections of trace elements and nutrients in samples were 

less than health-based thresholds. Exceptions include three 

detections of arsenic and three detections of nitrite plus nitrate 

as nitrogen (NO2

–+NO3–) greater than the USEPA maximum 

contaminant level (MCL-US) and eight detections of 

molybdenum greater than the USEPA lifetime health advisory 

level (HAL-US). All detections of gross alpha and gross beta 

radioactivity in SCRC grid wells were less than health-based 

thresholds. 

Concentrations for most samples from 32 SCRC grid 

wells collected for trace elements and major ions measured 

less than the non-enforceable thresholds set for aesthetic 

concerns. Iron concentrations greater than the CDPH 

secondary maximum contaminant level (SMCL-CA) of 

300 μg/L (micrograms per liter) were detected in five grid 

wells. Manganese concetrations greater than the SMCL-CA 

of 50 μg/L were detected in nine grid wells and chloride 

concentrations greater than the recommended SMCL-CA 

threshold of 250 mg/L (milligrams per liter) were measured 

in one grid well. Sulfate concentrations greater than the 

recommended SMCL-CA threshold of 250 mg/L were 

measured in 14 grid wells and 3 of these wells also were 

greater than the upper SMCL-CA threshold of 500 mg/L. 

TDS concentrations greater than the SMCL-CA recommended 

threshold were measured in 25 grid wells and concentrations 

in 5 of these wells also were greater than the SMCL-CA 

upper threshold (SMCL-CA threshold for TDS has a 
18 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

recommended value of 500 mg/L and an upper threshold value 

of 1,000 mg/L). 

Results from the understanding wells in the SCRC study 

unit showed there were three detections of nitrite plus nitrate 

as nitrogen (NO2

–+NO3–) greater than the MCL-US and one 

detection of molybdenum measured greater than the HAL-US. 

Manganese concentrations greater than the SMCL-CA 

threshold 50 μg/L were measured in one understanding wells 

and sulfate concentrations greater than the recommended 

SMCL-CA threshold of 250 mg/L were measured in four 

understanding wells. TDS concentrations greater than the 

SMCL-CA recommended lower threshold were measured in 

six understanding wells sampled for TDS and concentrations 

also were greater than the upper threshold in four of these 

wells. 

All results from the three surface-water samples in the 

SCRC study unit were less than health-based thresholds with 

the exception of nitrite plus nitrate as nitrogen (NO2

–+NO3–); 

concentrations were greater than the MCL-US in all three 

samples. In addition, concentrations of all trace elements and 

most of the major ions in the surface-water samples were less 

than the non-enforceable thresholds set for aesthetic concerns. 

The exceptions include: sulfate concentrations greater than the 

recommended SMCL-CA threshold were detected in all three 

surface-water samples and greater than the upper SMCL-CA 

threshold in one sample and TDS concentrations greater than 

the upper SMCL-CA threshold were detected in all three 

surface-water samples.

Acknowledgments

The authors thank the following cooperators for their 

support: the 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 their 

generosity in allowing the USGS to collect samples from their 

wells.

References Cited

American Public Health Association, 1998, Standard 

methods for the examination of water and wastewater 

(20th ed.): Washington, D.C., American Public Health 

Association, American Water Works Association, and Water 

Environment Federation, p. 3-37–3-43.

Anderson, R.L., 1987, Practical statistics for analytical 

chemists: New York, Van Nostrand Reinhold Company, 

Inc., 315 p.

Barnes, Ivan, 1964, Field measurement of alkalinity and pH: 

U.S. Geological Survey Water-Supply Paper 1535-H, 17 p.

Belitz, Kenneth, Dubrovsky, N.M., Burow, K.R., Jurgens, 

Bryant, and Johnson, Tyler, 2003, Framework for a 

groundwater quality monitoring and assessment program 

for California: U.S. Geological Survey Water-Resources 

Investigations Report 03–4166, 78 p.

Bennett, G.L., V, Belitz, Kenneth, and Milby Dawson, B.J., 

2006, California GAMA Program—Groundwater quality 

data in the Northern San Joaquin basin study unit, 2005: 

U.S. Geological Survey Data Series 196, 122 p.

Bennett, P.A., Bennett, G.L., V, and Belitz, Kenneth, 2009, 

Groundwater quality data for the Northern Sacramento 

Valley, 2007—Results from the California GAMA program: 

U.S. Geological Survey Data Series 452, 90 p.

Brenton, R.W., and Arnett, T.L., 1993, Methods of analysis 

by the U.S. Geological Survey National Water-Quality 

Laboratory–determination of dissolved organic carbon 

by UV-promoted persulfate oxidation and infrared 

spectrometry: U.S. Geological Survey Open-File Report 

92-480, 12 p.

Bright, D.J., Stamos, C.L., Martin, P., and Nash, D.B., 1992, 

Ground-water hydrology and quality in the Lompoc area, 

Santa Barbara County, California, 1987-88: U.S. Geological 

Survey Water-Resources Investigations Report 91-4172, 77 

p.

Burton, C.A., and Belitz, Kenneth, 2008, Groundwater 

quality data in the Southeast San Joaquin Valley, 2005–

2006—Results from the California GAMA Program: U.S. 

Geological Survey Data Series 351, 103 p.

Busenberg, Eurybiades, Plummer, L. N., and Bartholomay, 

R.C., 2001, Estimated age and source of the young fraction 

of ground water at the Idaho National Engineering and 

Environmental Laboratory: U.S. Geological Survey WaterResources Investigations Report 01-4265, 144 p.

California Department of Public Health, 2008a, California 

drinking water-related laws–Drinking water-related 

regulations, Title 22: California Department of Public 

Health, accessed August 17, 2009, at http://www.cdph.

ca.gov/certlic/drinkingwater/Pages/Lawbook.aspx

California Department of Public Health, 2008b, Drinking 

water notification levels–Notification levels: California 

Department of Public Health,, accessed August 17, 2009, 

at http://www.cdph.ca.gov/certlic/drinkingwater/Pages/

NotificationLevels.aspx

California Department of Water Resources, 2003, California’s 

groundwater update 2003: California Department of Water 

Resources Bulletin 118, 246 p., accessed September 14, 

2009, at http://www.groundwater.water.ca.gov/bulletin118
References Cited 19

California Department of Water Resources, 2004a, California’s 

groundwater, Los Osos Valley Groundwater Basin: 

California Department of Water Resources Bulletin 118, 

accessed September 14, 2009, at http://www.water.ca.gov/

pubs/groundwater/bulletin_118/basindescriptions/3-8.pdf

California Department of Water Resources, 2004b, 

California’s groundwater, San Luis Obispo Valley 

Groundwater Basin: California Department of Water 

Resources Bulletin 118, accessed September 14, 2009, at 

http://www.water.ca.gov/pubs/groundwater/bulletin_118/

basindescriptions/3-9.pdf

California Department of Water Resources, 2004c, California’s 

groundwater, Santa Maria River Valley Groundwater Basin: 

California Department of Water Resources Bulletin 118, 

accessed September 14, 2009, at http://www.water.ca.gov/

pubs/groundwater/bulletin_118/basindescriptions/3-12.pdf

California Department of Water Resources, 2004d, 

California’s groundwater, San Antonio Creek Valley 

Groundwater Basin: California Department of Water 

Resources Bulletin 118, accessed September 14, 2009, at 

http://www.water.ca.gov/pubs/groundwater/bulletin_118/

basindescriptions/3-14.pdf

California Department of Water Resources, 2004e, California’s 

groundwater, Santa Ynez River Valley Groundwater Basin: 

California Department of Water Resources Bulletin 118, 

accessed September 14, 2009, at http://www.water.ca.gov/

pubs/groundwater/bulletin_118/basindescriptions/3-15.pdf

Carmody, R.W., Plummer, L.N., Busenburg, E., and Coplen, 

T.B., 1998, Methods for collection of dissolved sulfate and 

sulfide and analysis of their sulfur isotopic composition: 

U.S. Geological Survey Open-File Report 97-234, 101 p.

Childress, C.J.O., Foreman, W.T., Connor, B.F., and Maloney, 

T.J., 1999, New reporting procedures based on long-term 

method-detection levels and some considerations for 

interpretations of water-quality data provided by the U.S. 

Geological Survey National Water Quality Laboratory: U.S. 

Geological Survey Open-File Report 99-193, 19 p.

Clark, I.D., and Fritz, P., 1997, Environmental isotopes in 

hydrogeology: Boca Raton, Florida, CRC Press LLC, 328 p.

Connor, B.F., Rose, D.L., Noriega, M.C., Murtagh, L.K., 

and Abney, S.R., 1998, Methods of analysis by the U.S. 

Geological Survey National Water Quality Laboratory—

Determination of 86 volatile organic compounds in water 

by gas chromatography/mass spectrometry, including 

detections less than reporting limits: U.S. Geological 

Survey Open-File Report 97-829, 78 p.

Coplen, T.B., 1994, Reporting of stable hydrogen, carbon, and 

oxygen isotopic abundances: Pure and Applied Chemistry, 

v. 66, p. 273–276.

Coplen, T.B., Wildman, J.D., and Chen, J., 1991, 

Improvements in the gaseous hydrogen-water equilibrium 

technique for hydrogen isotope analysis: Analytical 

Chemistry, v. 63, p. 910–912.

Coplen, T.B., Hopple, J.A., Böhlke, J.K., Peiser, H.S., Rieder, 

S.E., Krouse, H.R., Rosman, K.J.R., Ding, T., Vocke, R.D., 

Jr., Revesz, K.M., Lamberty, A., Taylor, P., and DeBierve, 

P., 2002, Compilation of minimum and maximum isotope 

ratios of selected elements in naturally occurring terrestrial 

materials and reagents: U.S. Geological Survey WaterResources Investigations Report 01-4222, 98 p.

Dawson, B.J., Bennett, G.L., V, and Belitz, Kenneth, 2008, 

Ground-water quality data in the southern Sacramento 

Valley, California, 2005—Results from the California 

GAMA Program: U.S. Geological Survey Data Series 285, 

93 p. 

Densmore, J.N., Fram, M.S., and Belitz, Kenneth, 2009, 

Ground-water quality data in the Owens and Indian Wells 

Valleys study unit, 2006: Results from the California 

GAMA program: U.S. Geological Survey Data Series 427, 

86 p.

Eaton, G.F., Hudson, G.B., and Moran, J.E., 2004, Tritiumhelium-3 age-dating of groundwater in the Livermore Valley 

of California: American Chemical Society ACS Symposium 

Series, v. 868, p. 235–245.

Epstein, Samuel, and Mayeda, T.K., 1953, Variation of O-18 

content of water from natural sources: Geochimica et 

Cosmochimica Acta, v. 4, p. 213–224.

Faires, L.M., 1993, Methods of analysis by the U.S. 

Geological Survey National Water Quality Laboratory—

determination of metals in water by inductively coupled 

plasma-mass spectrometry: U.S. Geological Survey OpenFile Report 92-634, 28 p.

Faure, Gunter, and Mensing, T.M., 2005, Isotopes–Principles 

and Applications (3d ed.): Hoboken, New Jersey, John 

Wiley & Sons, Inc., 897 p.

Ferrari, M.J., Fram, M.S., and Belitz, Kenneth, 2008, Groundwater quality in the Central Sierra study unit, California, 

2006—Results from the California GAMA program: U.S. 

Geological Survey Data Series 335, 60 p.

Firestone, R.B., Shirley, V.S., Baglin, C.M., Chu, S.Y.F., and 

Zipkin, J., 1996, Table of isotopes (8th ed.): New York, John 

Wiley & Sons, 3168 p., accessed on July 16, 2009, at http://

ie.lbl.gov/toipdf/toi20.pdf

Fishman, M.J., 1993, Methods of analysis by the U.S. 

Geological Survey National Water Quality Laboratory—

determination of inorganic and organic constituents in water 

and fluvial sediments: U.S. Geological Survey Open-File 

Report 93-125, 217 p.
20 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Fishman, M.J., and Friedman, L.C., 1989, Methods for 

determination of inorganic substances in water and fluvial 

sediments: U.S. Geological Survey Techniques of WaterResources Investigations, book 5, chap. A1, 545 p.

Fram, M.S., and Belitz, Kenneth, 2007, Groundwater quality 

data in the Southern Sierra Study Unit, 2006—Results from 

the California GAMA Program: U.S. Geological Survey 

Data Series 258, 78 p.

Fram, M.S., Munday, C.M., and Belitz, Kenneth, 2009, 

Ground-water quality data for the Tahoe–Martis study unit, 

2007—Results from the California GAMA Program: U.S. 

Geological Survey Data Series 432, 80 p.

Furlong, E.T., Werner, S.L., Anderson, B.D., and Cahill, J.D., 

2008, Determination of human-health pharmaceuticals 

in filtered water by chemically modified styrenedivinylbenzene resin-based sold-phase extraction and highperformance liquid chromatography/mass spectrometry: 

U.S. Geological Survey Techniques and Methods, book 5, 

sec. B., chap. B5, 56 p.

Furlong, E.T., Anderson, B.D., Werner, S.L., Soliven, P.P., 

Coffey, L.J., and Burkhardt, M.R., 2001, Determination of 

pesticides in water by graphitized carbon-based solid-phase 

extraction and high-performance liquid chromatography/

mass spectrometry: U.S. Geological Survey WaterResources Investigations Report 01–4134, 73 p.

Garbarino, J.R., 1999, Methods of analysis by the U.S. 

Geological Survey National Water Quality Laboratory–

Determination of dissolved arsenic, boron, lithium, 

selenium, strontium, thalium, and vanadium using 

inductively coupled plasma-mass spectrometry: U.S. 

Geological Survey Open-File Report 99-093, 31 p.

Garbarino, J.R., and Damrau, D.L., 2001, Methods of analysis 

by the U.S. Geological Survey National Water Quality 

Laboratory—Determination of organic plus inorganic 

mercury in filtered and unfiltered natural water with cold 

vapor–atomic fluorescence spectrometry: U.S. Geological 

Survey Water-Resources Investigations Report 01–4132, 

16 p.

Garbarino, J.R., Kanagy, J.R., and Cree, M.E., 2006, 

Determination of elements in natural-water, biota, sediment, 

and soil samples using collision/reaction cell inductively 

coupled plasma-mass spectrometry: U.S. Geological Survey 

Techniques and Methods, book 5, chap. B1, 88 p.

Gilliom, R.J., Barbash, J.E., Crawford, C.G., Hamilton, 

P.A., Martin, J.D., Nakagaki, N., Nowell, L.H., Scott, 

J.C., Stackelberg, P.E., Thelin, G.P., and Wolock, D.M., 

2006, The quality of our nation’s waters—Pesticides in 

the nation’s streams and groundwater, 1992–2001: U.S. 

Geological Survey Circular 1291, 172 p.

Goldrath, D.A., Wright, M.T., and Belitz, Kenneth, 2009, 

Ground-water quality data in the Coachella Valley study 

unit, 2007—Results from the California GAMA Program: 

U.S. Geological Survey Data Series 373, 70 p.

Goldrath, D.A., Wright, M.T., and Belitz, Kenneth, 2010, 

Groundwater-quality data in the Colorado River study unit, 

2007: Results from the California GAMA program: U.S. 

Geological Survey Data Series 474, 66 p.

Gran, G., 1952, Determination of the equivalence point in 

potentiometric titration. Part II: Analyst, v. 77, p. 661.

Grob, R.L, ed., 1995, Modern practice of gas chromatography 

(3d ed.): New York, John Wiley & Sons, 888 p.

Hahn, G.J., and Meeker, W.Q., 1991, Statistical intervals—a 

guide for practitioners: New York, John Wiley & Sons, 

392 p. 

Hamlin, S.N., 1985, Ground-water quality in the Santa Rita, 

Buellton, and Los Olivos hydrologic subareas of the Santa 

Ynez River basin, Santa Barbara County, California: U.S. 

Geological Survey Water-Resources Investigations Report 

84-4131, 75 p.

Hoaglin, D.C., 1983, Letter values—A set of selected order 

statistics, in Hoaglin, D.C., Mosteller, F., and Tukey, J.W., 

eds., Understanding Robust and Exploratory Data Analysis: 

New York, John Wiley & Sons, p. 33–54.

Hutson, S.S., Barber, N.L., Kenny, J.F., Linsey, K.S., Lumia, 

D.S., and Maupin, M.A., 2004, Estimated use of water in 

the United States in 2000: U.S. Geological Survey Circular 

1268, 46 p.

Karlen, I., Olsson, I.U.,Kallburg, P., and Kilici, S., 1964. 

Absolute determination of the activity of two 14C dating 

standards: ArkivGeofysik, vol. 4, p. 465–471.

Kent, R. H., and Belitz, Kenneth, 2009, Ground-water 

quality data in the Upper Santa Ana Watershed Study Unit, 

November 2006 to March 2007: Results from the California 

GAMA Program: U.S. Geological Survey Data Series 404, 

116 p.

Kolpin, D.W., Furlong, E.T., Meyer, M.T., Thurman, E.M., 

Zaugg, S.D., Barber, L.B., and Buxton, H.T., 2002, 

Pharmaceuticals, hormones and other organic wastewater 

contaminants in U.S. streams, 1999–2000: Environmental 

Science & Technology, v. 36, no. 6, p. 1202–1211. 

Koterba, M.T., Wilde, F.D., and Lapham, W.W., 1995, 

Groundwater data-collection protocols and procedures 

for the National Water-Quality Assessment Program—

Collection and documentation of water-quality samples 

and related data: U.S. Geological Survey Open-File Report 

95-399, 113 p.
References Cited 21

Kreiger, H.L., and Whittaker, E.L., 1980, Prescribed 

procedures for measurement of radioactivity in drinking 

water: U.S. Environmental Protection Agency EPA-600-4-

80-032, 142 p. (Also available as PB80-224744 at http://

www.ntis.gov)

Kulongoski, J.T., and Belitz, Kenneth, 2004, Groundwater 

ambient monitoring and assessment program: U.S. 

Geological Survey Fact Sheet 2004–3088, 2 p.

Kulongoski, J.T., and Belitz, Kenneth, 2007, Groundwater 

quality data in the Monterey Bay and Salinas Valley Basins, 

California, 2005—Results from the California GAMA 

Program: U.S. Geological Survey Data Series 258, 84 p. 

Kulongoski, J.T., Belitz, Kenneth, and Dawson, B.J., 2006, 

Ground-water quality data in the North San Francisco 

Bay Hydrologic provinces, California, 2004: Results from 

the California Ground-Water Ambient Monitoring and 

Assessment (GAMA) Program: U.S. Geological Survey 

Data Series 167, 100 p. 

Land, M.T., and Belitz, Kenneth, 2008, Groundwater 

quality data in the San Fernando–San Gabriel study unit, 

2005—Results from the California GAMA Program: U.S. 

Geological Survey Data Series 356, 84 p.

Landon, M.K., and Belitz, Kenneth, 2008, Groundwater 

quality data in the Central Eastside San Joaquin Basin 

2006:Results from the California GAMA Program: U.S. 

Geological Survey Data Series 325, 88 p.

Landon, M.K., Belitz, Kenneth, Jurgens, B.C., Kulongoski, 

J.T., and Johnson, T.D., 2010, Status and understanding of 

groundwater quality in the Central–Eastside San Joaquin 

Basin, 2006: California GAMA Priority Basin project: U.S. 

Geological Survey Scientific Investigations Report 2009–

5266, 97 p. 

Lane, S.L., Flanagan, Sarah, and Wilde, F.D., 2003, Selection 

of equipment for water sampling (ver. 2.0): U.S. Geological 

Survey Techniques of Water-Resources Investigations, 

book 9, chap. A2, accessed September 17, 2009, at http://

pubs.water.usgs.gov/twri9A2/

Lewis, M.E., 2006, Dissolved oxygen (ver. 2.1): U.S. 

Geological Survey Techniques of Water-Resources 

Investigations, book 9, chap. A6.2, accessed August 18, 

2009, at http://pubs.water.usgs.gov/twri9A6.2/

Lindley, C.E., Stewart, J.T., and Sandstrom, M.W., 1996, 

Determination of low concentrations of acetochlor in 

water by automated solid-phase extraction and gas 

chromatography with mass selective detection: Journal of 

AOAC International, v. 79, no. 4, p. 962–966.

Madsen, J.E., Sandstrom, M.W., and Zaugg, S.D., 2003, 

Methods of analysis by the U.S. Geological Survey 

National Water Quality Laboratory—A method supplement 

for the determination of fipronil and degradates in water by 

gas chromatography/mass spectrometry: U.S. Geological 

Survey Open-File Report 02–462, 11 p.

Maloney, T.J., ed., 2005, Quality management system, U.S. 

Geological Survey National Water Quality Laboratory: U.S. 

Geological Survey Open-File Report 2005–1263, accessed 

September 8, 2009, at http://pubs.usgs.gov/of/2005/1263/.

Mathany, T.M., and Belitz, Kenneth, 2009, Ground-water 

quality data in the Mojave Study Unit, 2008: Results from 

the California GAMA Program: U.S. Geological Survey 

Data Series 440, 80 p.

Mathany, T.M., Land, Michael, and Belitz, Kenneth, 2008, 

Groundwater quality data in the Coastal Los Angeles Basin 

Study Unit, 2006: Results from the California GAMA 

Program: U.S. Geological Survey Data Series 387, 98 p.

Mathany, T.M., Kulongski, J.T., Ray, M.C., and Belitz, 

Kenneth, 2009, Groundwater-quality data in the South 

Coast Interior Basins study unit, 2008: Results from the 

California GAMA program: U.S. Geological Survey Data 

Series 463, 82 p. 

McCleskey, R.B., Nordstrom, D.K., and Ball, J.W., 2003, 

Metal interferences and their removal prior to the 

determination of As(T) and As(III) in acid mine waters by 

hydride generation atomic absorption spectrometry: U.S. 

Geological Survey Water-Resources Investigations Report 

03–4117, 14 p.

McCurdy, D.E., Garbarino, J.R., and Mullin, A.H., 2008, 

Interpreting and reporting radiological water-quality data: 

U.S. Geological Survey Techniques and Methods, book 5, 

chap. B6, 33 p.

McLain, B., 1993, Methods of analysis by the U.S. Geological 

Survey National Water Quality Laboratory–Determination 

of chromium in water by graphite furnace atomic absorption 

spectrophotometry: U.S. Geological Survey Open-File 

Report 93-449, 16 p.

Montrella, Joseph, and Belitz, Kenneth, 2009, Groundwater 

quality data in the Santa Clara River Valley study unit, 

2007: Results from the California GAMA Program: U.S. 

Geological Survey Data Series 408, 84 p.

Moran, J.E., Hudson, G.B., Eaton, G.F., and Leif, R., 

2002, A contamination vulnerability assessment for the 

Livermore–Amador and Niles Cone Groundwater Basins: 

Lawrence Livermore National Laboratory internal report 

UCRL-AR-148831, 25 p.
22 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Mueller, D.K., and Titus, C.J., 2005, Quality of nutrient data 

from streams and ground water sampled during water 

years 1992–2001: U.S. Geological Survey Scientific 

Investigations Report 2005–5106, 27 p.

Okamoto, H.S., Steeber, W.R., Remoy, R., Hill P., and Perera, 

S.K., eds., 2002, Determination of 1,2,3-trichloropropane 

in drinking water by purge and trap gas chromatography/

mass spectrometry: California Department of Health 

Services, Division of Drinking Water and Environmental 

Management, Sanitation and Radiation Laboratories 

Branch, accessed September 4, 2009 at http://www.cdph.

ca.gov/certlic/drinkingwater/Documents/Drinkingwaterlabs/

TCPbyPT-GCMS.pdf

Olsen, L.D., Fram, M.S., and Belitz, Kenneth, 2010, Review 

of trace-element field-blank data collected for the California 

Groundwater Ambient Monitoring and Assessment 

(GAMA) Program, May 2004–January 2008: U.S. 

Geological Survey Scientific Investigations Report 2009-

5220, 47 p.

Olsson, I.U., 1970, The use of oxalic acid as a standard, in

Olsson, I.U., ed., Radiocarbon Variations and Absolute 

Chronology, Nobel Symposium, 12th, Proceedings: New 

York, John Wiley & Sons, p. 17.

Patton, C.J., and Kryskalla, J.R., 2003, Methods of analysis 

by the U.S. Geological Survey National Water Quality 

Laboratory–Evaluation of alkaline persulfate digestion as 

an alternative to Kjeldahl digestion for determination of 

total and dissolved nitrogen and phosphorous in water: U.S. 

Geological Survey Water-Resources Investigations Report 

03–4174, 33 p.

Patton, C.J., and Truitt, E.P., 2000, Methods of analysis by the 

U.S. Geological Survey National Water Quality Laboratory–

Determination of ammonium plus organic nitrogen by a 

Kjeldahl digestion method and an automated photometric 

finish that includes digest cleanup by gas diffusion: U.S. 

Geological Survey Open-File Report 00-170, 31 p.

Pirkey, K.D., and Glodt, S.R., 1998, Quality control at the 

U.S. Geological Survey National Water Quality Laboratory: 

U.S. Geological Survey Fact-Sheet 026–98, 4 p., accessed 

February 12, 2010 at http://pubs.er.usgs.gov/usgspubs/fs/

fs02698 

Plomley, J.B., Koester, C.J., and March, R.E., 1994, 

Determination of NDMA in complex environmental 

matrices by quadrupole ion storage tandem mass 

spectrometry enhanced by unidirectional ion ejection: 

Analytical Chemistry, v. 66, no. 24, p. 4437–4443.

Price, C.V., Nakagaki, N., Hitt, K.J., and Clawges, R.M., 

2003, Mining GIRAS–improving on a national treasure 

of land use data, in Conference of the ESRI International 

Users, 23rd, Redlands, Calif., July 7–11, 2003, Proceedings: 

Redlands, Calif., ESRI, 11 p.

Radtke, D.B., Davis, J.V., and Wilde, F.D., 2005, Specific 

electrical conductance (ver. 1.2): U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 9, 

chap. A6.3, accessed August 17, 2009 at http://pubs.water.

usgs.gov/twri9A6.3/

Ray, M.C., Kulongoski, J.T., and Belitz, Kenneth, 2009, 

Groundwater quality data in the San Francisco Bay study 

unit, 2007: Results from the California GAMA program: 

U.S. Geological Survey Data Series 396, 92 p. 

Révész, K., and Casciotti, K., 2007, Determination of the 

δ(15N/14N) and δ(18O/16O) of nitrate in water: RSIL Lab 

Code 2900, chap. C17 in Révész, Kinga, and Coplen, T.B., 

eds., Methods of the Reston Stable Isotope Laboratory: 

U.S. Geological Survey Techniques and Methods, book 10, 

sec. C, chap. 17, 24 p.

Sandstrom, M.W., Stroppel, M.E., Foreman, W.T., and 

Schroeder, M.P., 2001, Methods of analysis by the U.S. 

Geological Survey National Water Quality Laboratory–

Determination of moderate-use pesticides and selected 

degradates in water by C-18 solid-phase extraction and 

gas chromatography/mass spectrometry: U.S. Geological 

Survey Water-Resources Investigations Report 01–4098, 

70 p.

Saucedo, G.J., Bedford, D.R., Raines, G.L., Miller, R.J., 

and Wentworth, C.M., 2000, GIS data for the geologic 

map of California (version 2.0): California Department of 

Conservation, Division of Mines and Geology, Sacramento, 

Calif., CD 2000–07.

Schmitt, S.J., Fram, M.S., Milby Dawson, B.J., Belitz, 

Kenneth, 2008, Ground-water quality data in the Middle 

Sacramento Valley study unit, 2006—Results from the 

California GAMA program: U.S. Geological Survey Data 

Series 385, 100 p.

Scott, J.C., 1990, Computerized stratified random site 

selection approaches for design of a ground-water quality 

sampling network: U.S. Geological Survey Water-Resources 

Investigations Report 90-4101, 109 p.

Shelton, J.L., Fram, M.S., and Belitz, Kenneth, 2009, 

Groundwater-quality data for the Madera-Chowchilla study 

unit, 2008: Results from the California GAMA program: 

U.S. Geological Survey Data Series 455, 80 p. 

Shelton, J.L., Burow, K.R., Belitz, Kenneth, Dubrovsky, N.M., 

Land, M.T., and Gronberg, J.M., 2001, Low-level volatile 

organic compounds in active public supply wells as groundwater tracers in the Los Angeles physiographic basin, 

California, 2000: U.S. Geological Survey Water-Resources 

Investigations Report 01–4188, 29 p.
References Cited 23

Shelton, J.L., Pimentel, I., Fram, M.S., Belitz, Kenneth, 2008, 

Ground-water quality in the Kern County Subbasin Study 

Unit, 2006—Results from the California GAMA Program: 

U.S. Geological Survey Data Series 337, 75 p.

Soddy, F, 1913, Radioactivity: Annual Reports on the Progress 

of Chemistry, v. 10, p. 262–288.

State Water Resources Control Board, 2003, Report to the 

Governor and Legislature, A comprehensive groundwater 

quality monitoring program for California: Assembly Bill 

599 March 2003, 121 p., accessed February 12, 2010, at 

http://www.waterboards.ca.gov/gama/docs/final_ab_599_

rpt_to_legis_7_31_03.pdf

Stookey, L.L., 1970, FerroZine–A new spectrophotometric 

reagent for iron: Analytical Chemistry, v. 42, p. 779–781.

Stuiver, M., 1980,Workshop on 14C data reporting: 

Radiocarbon, v. 22, p. 964–966.

Stuiver, M., and Polach, H.A., 1977, Discussion–Reporting of 

14C data: Radiocarbon, v. 19, p. 355–363.

Thatcher, L.L., Janzer, V.J., and Edwards, K.W., 1977, 

Methods for the determination of radioactive substances 

in water: U.S. Geological Survey Techniques of WaterResources Investigations, book 5, chap. A5, 95 p.

Timme, P.J., 1995, National Water Quality Laboratory 1995 

services catalog: U.S. Geological Survey Open-File Report 

95-352, 120 p.

To, T.B., Nordstrom, D.K., Cunningham, K.M., Ball, J.W., 

and McCleskey, R.B., 1998, New method for the direct 

determination of dissolved Fe(III) concentration in acid 

mine waters: Environmental Science and Technology, v. 33, 

p. 807–813.

U.S. Environmental Protection Agency, 1989, Semivolatile 

organic compounds by isotope dilution GSMS (July 1989): 

Washington, D.C., U.S. Environmental Protection Agency, 

68 p.

U.S. Environmental Protection Agency, 2002, Guidelines for 

establishing procedures for the analysis of pollutants: U.S. 

Code of Federal Regulations, Title 40, 136 p.

U.S. Environmental Protection Agency, 2005, Method 331.0–

Determination of perchlorate in drinking water by liquid 

chromatography electrospray ionization mass spectrometry 

(Revision 1.0, January 2005): Office of Groundwater 

and Drinking Water, EPA Document # 815-R-05-007, 34 

p., accessed September 3, 2009, at http://www.epa.gov/

safewater/methods/pdfs/methods/met331_0.pdf

U.S. Environmental Protection Agency, 2008a, Drinking water 

contaminants, accessed September 2, 2009, at http://www.

epa.gov/safewater/contaminants/index.html

U.S. Environmental Protection Agency, 2008b, Drinking 

water health advisories–2006. Drinking water standards 

and health advisory tables, accessed September 2, 2009, at 

http://www.epa.gov/waterscience/criteria/drinking

U.S. Geological Survey, 2008, Branch of Quality Systems, 

Inorganic blind sample project, accessed September 10, 

2009, at http://bqs.usgs.gov/bsp/ (As of May 18, 2010, 

accessible at http://bqs.usgs.gov/ibsp/index.shtml)

U.S. Geological Survey, [variously dated], National field 

manual for the collection of water-quality data: U.S. 

Geological Survey Techniques of Water-Resources 

Investigations, book 9, chap. A1–A9, accessed September 7, 

2009, at http://water.usgs.gov/owq/FieldManual/

Valentine, D.W., Densmore, J.N., Galloway, D.L., and 

Amelung, F., 2001, Use of InSAR to identify land-surface 

displacements caused by aquifer-system compaction in the 

Paso Robles Area, San Luis Obispo County, California, 

March to August 1997: U.S. Geological Survey Open-File 

Report 00-447, 1 p.

 Volgelmann, J.E., Howard, S.M.,Yang, L., Larson, C.R., 

Wylie, B.K., and Van Driel, N., 2001, Completion of the 

1990s National Land Cover Data Set for the conterminous 

Unites States from Landsat Thematic Mapper data and 

ancillary data sources: Photogrammetric Engineering & 

Remote Sensing, v. 17, p. 150–612.

Water Education Foundation, 2006, Where does my water 

come from?: Sacramento, California, Water Education 

Foundation, accessed September 10, 2009, at http://www.

water-ed.org/watersources/default.asp

Weiss, R.F., 1968, Piggyback sampler for dissolved gas 

studies on sealed water samples: Deep Sea Research, v. 15, 

p. 721–735.

Wilde, F.D., ed., 2004, Cleaning of equipment for water 

sampling (ver. 2.0): U.S. Geological Survey Techniques of 

Water-Resources Investigations, book 9, chap. A3, accessed 

September 7, 2009, at http://pubs.water.usgs.gov/twri9A3/

Wilde, F.D., 2006, Temperature (ver. 2): U.S. Geological 

Survey Techniques of Water-Resources Investigations, book 

9, chap. A6.1, accessed September 7, 2009, at http://pubs.

water.usgs.gov/twri9A6.1/

Wilde, F.D., Busenberg, E., and Radtke, D.B., 2006, pH 

(ver. 1.3): U.S. Geological Survey Techniques of WaterResources Investigations, book 9, chap. A6.4, accessed 

September 7, 2009, at http://pubs.water.usgs.gov/twri9A6.4/

Wilde, F.D., and Radtke, D.B., 2005, Field measurements 

(ver. 1.2): U.S. Geological Survey Techniques of WaterResources Investigations, book 9, chap. A6.0, accessed 

September 7, 2009, at http://pubs.water.usgs.gov/twri9A6.0/
24 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Wilde, F.D., Radtke, D.B., Gibs, J., and Iwatsubo, R.T., 1999, 

Collection of water samples: U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 9, 

chap. A4, accessed September 7, 2009, at http://pubs.water.

usgs.gov/twri9A4/

Wilde, F.D., Radtke, D.B., Gibs, J., and Iwatsubo, R.T., 2004, 

Processing of water samples: U.S. Geological Survey 

Techniques of Water-Resources Investigations, book 9, 

chap. A5, accessed September 7, 2009, at http://pubs.water.

usgs.gov/twri9A5/

Wright, M.T., Belitz, Kenneth, and Burton, C.A., 2005, 

California GAMA program—Ground-water quality data in 

the San Diego drainages hydrologic province, California, 

2004: U.S. Geological Survey Data Series 129, 91 p.

Yurewicz, M.C., 1981, Incremental field titration of 

bicarbonate: U.S. Geological Survey Water Resources 

Division Bulletin, October–December 1981, p. 8–13.

Zaugg, S.D., Sandstrom, M.W., Smith, S.G., and Fehlberg, 

K.M., 1995, Methods of analysis by the U.S. Geological 

Survey National Water Quality Laboratory—Determination 

of pesticides in water by C-18 solid-phase extraction and 

capillary-column gas chromatography/mass spectrometry: 

U.S. Geological Survey Open-File Report 95-181, 60 p.
Tables 25

Tables
26 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table 1. Identification, sampling, and construction information for wells and identification and sampling information for surface-water 

sites sampled for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, 

May to December 2008.—Continued

[GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, 

understanding well. Other abbreviations: ft, foot; LSD, land surface datum; NAVD 88, North American Vertical Datum 1988; na, not available; nv, no value in 

category]

Sampling information Construction information

GAMA 

identification 

number

Date 

sampled

(m/dd/ yyyy)

Sampling 

schedule 1

Altitude of LSD 

(ft above 

NAVD 88) 2

Well type Well depth 

(ft below LSD)

Top 

perforation 

(ft below LSD)

Bottom 

perforation 

(ft below LSD)

SCRC Grid wells

SCRC-B01 5/19/2008 Fast 90 Production 607 305 595

SCRC-B02 5/20/2008 Fast 133 Production 140 40 130

SCRC-B03 5/21/2008 Fast 195 Production na na na

SCRC-B04 5/21/2008 Fast 97 Production 550 340 527

SCRC-B05 5/22/2008 Slow 423 Production 651 523 na

SCRC-B06 5/22/2008 Fast 643 Production na na na

SCRC-B07 6/2/2008 Fast 533 Production 500 100 500

SCRC-B08 6/4/2008 Slow 355 Production 1,120 550 1,100

SCRC-B09 6/10/2008 Fast 756 Production 349 150 340

SCRC-B10 6/11/2008 Slow 593 Production 490 190 470

SCRC-B11 6/12/2008 Slow 100 Monitoring 68 na na

SCRC-B12 6/12/2008 Fast 553 Production 103 60 na

SCRC-B13 6/16/2008 Fast 633 Production 490 130 470

SCRC-B14 6/18/2008 Fast 221 Production 946 279 946

SCRC-B15 6/18/2008 Fast 151 Production 463 na na

SCRC-B16 6/19/2008 Slow 230 Production 370 185 365

SCRC-B17 6/19/2008 Fast 241 Production 191 135 na

SCRC-B18 6/23/2008 Fast 303 Production 210 98 na

SCRC-B19 6/23/2008 Fast 380 Production 512 125 507

SCRC-B20 6/24/2008 Fast 523 Production 115 95 na

SCRC-B21 6/25/2008 Slow 38 Production 190 na na

SCRC-B22 6/25/2008 Slow 125 Production 350 na na

SCRC-B23 7/7/2008 Slow plus special

study

262 Production 620 375 600

SCRC-B24 7/7/2008 Fast 282 Production 600 na na

SCRC-B25 7/9/2008 Fast 195 Production 401 160 400

SCRC-B26 7/10/2008 Slow 26 Production 180 na na

SCRC-B27 7/14/2008 Slow plus special

study

125 Production 420 260 420

SCRC-B28 7/15/2008 Slow plus special

study

371 Production 390 300 380

SCRC-B29 7/15/2008 Fast plus special

study

308 Production 225 33 120

SCRC-B30 7/16/2008 Slow plus special

study

89 Production 418 338 na

Table 1. Identification, sampling, and construction information for wells and identification and sampling information for surface-water 

sites sampled for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, 

May to December 2008.

[GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, 

understanding well. Other abbreviations: ft, foot; LSD, land surface datum; NAVD 88, North American Vertical Datum 1988; na, not available; nv, no value in 

category]
Tables 27

Table 1. Identification, sampling, and construction information for wells and identification and sampling information for surface-water 

sites sampled for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, 

May to December 2008.—Continued

[GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, 

understanding well. Other abbreviations: ft, foot; LSD, land surface datum; NAVD 88, North American Vertical Datum 1988; na, not available; nv, no value in 

category]

Sampling information Construction information

GAMA 

identification 

number

Date 

sampled

(m/dd/ yyyy)

Sampling 

schedule 1

Altitude of LSD 

(ft above 

NAVD 88) 2

Well type Well depth 

(ft below LSD)

Top 

perforation 

(ft below LSD)

Bottom 

perforation 

(ft below LSD)

SCRC-B31 7/16/2008 Fast 83 Production na na na

SCRC-B32 7/17/2008 Fast 97 Production 300 102 na

SCRC-B33 7/28/2008 Fast 531 Production 830 605 825

SCRC-B34 7/28/2008 Slow 364 Production 707 542 705

SCRC-B35 7/30/2008 Fast 93 Production 140 80 140

SCRC-B36 8/4/2008 Slow plus special

study

105 Production 200 na na

SCRC-B37 8/7/2008 Slow 74 Production 232 112 212

SCRC-B38 8/7/2008 Fast 358 Production na na na

SCRC-B39 11/20/2008 Slow 33 Monitoring 615 527 615

SCRC-H01 5/19/2008 Slow 124 Production 460 160 440

SCRC-H02 6/2/2008 Slow 1,263 Production na na na

SCRC-H03 6/3/2008 Slow 639 Production 550 350 550

SCRC-H04 6/3/2008 Slow 1,059 Production 620 410 610

SCRC-H05 6/5/2008 Slow 1,200 Production 720 310 720

SCRC-H06 6/9/2008 Slow 505 Production 345 215 335

SCRC-H07 6/9/2008 Slow 343 Production 390 200 na

SCRC-H08 6/10/2008 Slow 958 Production 920 535 910

SCRC-H09 6/16/2008 Slow 1,017 Production 750 na na

SCRC-H10 6/24/2008 Slow 1,322 Production 600 420 600

SCRC-H11 6/26/2008 Slow 322 Production 260 200 260

SCRC-H12 7/8/2008 Slow 731 Production 645 105 645

SCRC-H13 7/23/2008 Slow 836 Production 980 290 960

SCRC-H14 7/29/2008 Slow 253 Production 300 150 290

SCRC-H15 8/5/2008 Slow 1,414 Production 1,263 448 1,253

SCRC-H16 11/18/2008 Slow 999 Production 280 75 270

SCRC Surface-water sites

SCRC-SW1 8/6/2008 Surface-water 83 nv nv nv nv

SCRC-SW2 8/6/2008 Surface-water 49 nv nv nv nv

SCRC-SW3 8/6/2008 Surface-water 52 nv nv nv nv
28 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table 1. Identification, sampling, and construction information for wells and identification and sampling information for surface-water 

sites sampled for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, 

May to December 2008.—Continued

[GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, 

understanding well. Other abbreviations: ft, foot; LSD, land surface datum; NAVD 88, North American Vertical Datum 1988; na, not available; nv, no value in 

category]

Sampling information Construction information

GAMA 

identification 

number

Date 

sampled

(m/dd/ yyyy)

Sampling 

schedule 1

Altitude of LSD 

(ft above 

NAVD 88) 2

Well type Well depth 

(ft below LSD)

Top 

perforation 

(ft below LSD)

Bottom 

perforation 

(ft below LSD)

SCRC Understanding wells

SCRC-U01 7/29/2008 Fast 32 Production 130 na na

SCRC-U02 7/30/2008 Fast 63 Production 174 134 174

SCRC-U03 7/8/2008 Slow 357 Production 600 300 590

SCRC-U04 7/9/2008 Fast plus special

study

209 Production 125 115 125

SCRC-U05 7/24/2008 Fast 102 Monitoring 55 35 55

SCRC-U06 7/24/2008 Slow plus special

study

253 Production 582 na na

SCRC-U07 7/31/2008 Slow plus special

study

131 Production 179 110 na

SCRC-U08 7/31/2008 Slow plus special

study

151 Production 335 na na

SCRC-U09 8/4/2008 Slow plus special

study

141 Production 186 na na

SCRC-U10 8/5/2008 Slow plus special

study

143 Production na na na

SCRC-U11 7/21/2008 Fast 203 Monitoring 19 10 19

SCRC-U12 7/21/2008 Fast 452 Monitoring 77 72 77

SCRC-U13 7/22/2008 Fast 174 Monitoring 23 8 23

SCRC-U14 7/22/2008 Fast 183 Monitoring 18 8 18

SCRC-U15 7/22/2008 Slow 36 Monitoring 38 8 38

1

 Sampling schedules are described in table 2.

2

 Land-surface datum (LSD) is a datum plane that is approximately at land surface at each well. The altitude of the LSD is described in feet above the North 

American Vertical Datum 1988.
Tables 29

Analyte classes Slow schedule Fast schedule Special study schedule Surface- water schedule Analyte list table Results table

Field water-quality indicators 

Dissolved oxygen, temperature, pH, and specific conductance X X X 4Turbidity X X 4Field alkalinity, bicarbonate, and carbonate X 4

Organic constituents

Volatile organic compounds (VOC) X X 3A 5Pesticides and pesticide degradates X X 3B 6APolar pesticides and metabolites X X 3C 6BPharmaceutical compounds X 3D none 1

Constituents of special interest

Perchlorate X X 3E 7N-nitrosodimethylamine (NDMA) X 3E none 21,2,3-TCP X X 3E none 2

Inorganic constituents

Trace elements X X 3F 8Nutrients X X 3G 9Dissolved organic carbon (DOC) X 3G 9Major and minor ions, silica, total dissolved solids (TDS), and laboratory alkalinity X X 3H 10Arsenic and iron speciation X 3I 11

Stable isotopes

Stable isotopes of hydrogen and oxygen in water X X X 3J 12Stable isotopes of nitrogen and oxygen in dissolved nitrate X X 3J 12Stable isotopes of sulfur in dissolved sulfate X 3J none 1Stable isotopes of carbon in dissolved inorganic carbon and carbon-14 abundance X 3J 12

Radioactivity and dissolved gases

Tritium X X 3J 12Dissolved gases X 3K 13Gross alpha and gross beta radiation X 3J 14Dissolved noble gases and tritium X X 3K none 1

Table 2. Classes of chemical constituents and field water-quality indicators collected for the slow, fast, and special study well sampling schedules and the surface-water schedule in the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.
30 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table 3A. Volatile organic compounds (VOC), primary uses or sources, comparative thresholds, 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. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: 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 5); 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) Threshold type 2 Threshold level (μg/L) Detection Acetone Solvent 81552 67-64-1 4 na na

—

Acrylonitrile Organic synthesis 34215 107-13-1 0.4 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 0.016 MCL-CA 1 —Bromobenzene Solvent 81555 108-86-1 0.02 na na

—

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

—

Bromodichloromethane Disinfection by-product (THM) 32101 75-27-4 0.04 MCL-US 3 80

—

Bromoform (Tribromomethane) Disinfection by-product (THM) 32104 75-25-2 0.1 MCL-US 3 80

—

Bromomethane (Methyl bromide) Fumigant 34413 74-83-9 0.4 HAL-US 10

—

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

—

sec-Butylbenzene Gasoline hydrocarbon 77350 135-98-8 0.02 NL-CA 260

—

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

—

Carbon disulfide Organic synthesis 77041 75-15-0 0.04 NL-CA 160

—

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

—

Chlorobenzene Solvent 34301 108-90-7 0.02 MCL-CA 70

—

Chloroethane Solvent 34311 75-00-3 0.10 na na

—

Chloroform (Trichloromethane) Disinfection by-product (THM) 32106 67-66-3 0.04 MCL-US 3 80

D

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

—

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

—

2-Chlorotoluene Solvent 77275 95-49-8 0.02 NL-CA 140

—

4-Chlorotoluene Solvent 77277 106-43-4 0.02 NL-CA 140

—

Dibromochloromethane Disinfection by-product (THM) 32105 124-48-1 0.12 MCL-US 3 80

—

1,2-Dibromo-3-chloropropane (DBCP) Fumigant 82625 96-12-8 1 MCL-US 0.2

—

1,2-Dibromoethane (EDB) Fumigant 77651 106-93-4 0.04 MCL-US 0.05

—

Dibromomethane Solvent 30217 74-95-3 0.04 na na

—

Table 3A. Volatile organic compounds (VOC), primary uses or sources, comparative thresholds, 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. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: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 5); na, not available; μg/L, micrograms per liter; —, not detected]
Tables 31

Table 3A. Volatile organic compounds (VOC), primary uses or sources, comparative thresholds, 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. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: 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 5); 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) Threshold type 2 Threshold level (μg/L) Detection

1,2-Dichlorobenzene Solvent 34536 95-50-1 0.02 MCL-CA 600 —1,3-Dichlorobenzene Solvent 34566 541-73-1 0.02 HAL-US 600 —1,4-Dichlorobenzene Fumigant 34571 106-46-7 0.02 MCL-CA 5 —trans-1,4-Dichloro-2-butene Organic synthesis 73547 110-57-6 0.4 na na —Dichlorodifluoromethane (CFC-12) Refrigerant 34668 75-71-8 0.1 NL-CA 1,000 D1,1-Dichloroethane (1,1-DCA) Solvent 34496 75-34-3 0.04 MCL-CA 5 —1,2-Dichloroethane (1,2-DCA) Solvent 32103 107-06-2 0.06 MCL-CA 0.5 —1,1-Dichloroethene (1,1-DCE) Organic synthesis 34501 75-35-4 0.02 MCL-CA 6 Dcis-1,2-Dichloroethene (cis-1,2-DCE) Solvent 77093 156-59-2 0.02 MCL-CA 6 Dtrans-1,2-Dichloroethene (trans-1,2-DCE) Solvent 34546 156-60-5 0.018 MCL-CA 10 D1,2-Dichloropropane Fumigant 34541 78-87-5 0.02 MCL-US 5 D1,3-Dichloropropane Fumigant 77173 142-28-9 0.06 na na —2,2-Dichloropropane Fumigant 77170 594-20-7 0.06 na na —1,1-Dichloropropene Organic synthesis 77168 563-58-6 0.04 na na —cis-1,3-Dichloropropene Fumigant 34704 10061-01-5 0.1 RSD5-US 4 4 —trans-1,3-Dichloropropene Fumigant 34699 10061-02-6 0.10 RSD5-US 4 4 —Diethyl ether Solvent 81576 60-29-7 0.12 na na —Diisopropyl ether (DIPE) Gasoline oxygenate 81577 108-20-3 0.06 na na —Ethylbenzene Gasoline hydrocarbon 34371 100-41-4 0.04 MCL-CA 300 —Ethyl tert-butyl ether (ETBE) Gasoline oxygenate 50004 637-92-3 0.04 na na —Ethyl methacrylate Organic synthesis 73570 97-63-2 0.14 na na —o-Ethyl toluene (1-Ethyl-2-methyl benzene) Gasoline hydrocarbon 77220 611-14-3 0.02 na na —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 0.6 na na —
32 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table 3A. Volatile organic compounds (VOC), primary uses or sources, comparative thresholds, 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. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: 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 5); 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) Threshold type 2 Threshold level (μg/L) Detection Iodomethane (Methyl iodide) Organic synthesis 77424 74-88-4 0.8 na na

—

Isopropylbenzene Gasoline hydrocarbon 77223 98-82-8 0.04 NL-CA 770

—

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

—

Methyl acrylate Organic synthesis 49991 96-33-3 0.6 na na

—

Methyl acrylonitrile Organic synthesis 81593 126-98-7 0.2 na na

—

Methyl tert-butyl ether (MTBE) Gasoline oxygenate 78032 1634-04-4 0.10 MCL-CA 13

D

Methyl iso-butyl ketone (MIBK) Solvent 78133 108-10-1 0.4 NL-CA 120

—

Methylene chloride (Dichloromethane) Solvent 34423 75-09-2 0.04 MCL-US 5 DMethyl ethyl ketone (2-butanone, MEK) Solvent 81595 78-93-3 1.6 HAL-US 4,000

—

Methyl methacrylate Organic synthesis 81597 80-62-6 0.20 na na

—

Naphthalene Gasoline hydrocarbon 34696 91-20-3 0.2 NL-CA 17

—

Perchloroethene (PCE, Tetrachloroethene) Solvent 34475 127-18-4 0.04 MCL-US 5 Dn-Propylbenzene Solvent 77224 103-65-1 0.04 NL-CA 260

—

Styrene Gasoline hydrocarbon 77128 100-42-5 0.04 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 0.10 MCL-CA 1 —Tetrahydrofuran Solvent 81607 109-99-9 1.4 na na

D

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

—

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

—

Toluene Gasoline hydrocarbon 34010 108-88-3 0.018 MCL-CA 150

D

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

—

1,2,4-Trichlorobenzene Solvent 34551 120-82-1 0.04 MCL-CA 5 —1,1,1-Trichloroethane (1,1,1-TCA) Solvent 34506 71-55-6 0.02 MCL-CA 200

—

1,1,2-Trichloroethane (1,1,2-TCA) Solvent 34511 79-00-5 0.06 MCL-CA 5 —Trichloroethene (TCE) Solvent 39180 79-01-6 0.02 MCL-US 5 D
Tables 33

Table 3A. Volatile organic compounds (VOC), primary uses or sources, comparative thresholds, 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. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: 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 5); 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) Threshold type 2 Threshold level (μg/L) Detection

Trichlorofluoromethane (CFC-11) Refrigerant 34488 75-69-4 0.08 MCL-CA 150 D1,2,3-TCP Solvent/organic synthesis 77443 96-18-4 0.12 HAL-US 5 40 —Trichlorotrifluoroethane (CFC-113) Refrigerant 77652 76-13-1 0.04 MCL-CA 1,200 —1,2,3-Trimethylbenzene Gasoline hydrocarbon 77221 526-73-8 0.08 na na —1,2,4-Trimethylbenzene Gasoline hydrocarbon 77222 95-63-6 0.04 NL-CA 330 —1,3,5-Trimethylbenzene Organic synthesis 77226 108-67-8 0.04 NL-CA 330 —Vinyl bromide (Bromoethene) Fire retardant 50002 593-60-2 0.12 na na —Vinyl chloride (Chloroethene) Organic synthesis 39175 75-01-4 0.08 MCL-CA 0.5 Dm- and p-Xylene Gasoline hydrocarbon 85795 108-38-3 / 106-42-3 0.08 MCL-CA 6 1,750 —o-Xylene Gasoline hydrocarbon 77135 95-47-6 0.04 MCL-CA 6 1,750 —

1 This report contains CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs through CAS Client ServicesSM.2 Maximum contaminant level thresholds 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.3 The MCL-US thresholds for trihalomethanes is the sum of chloroform, bromoform, bromodichloromethane, and dibromochloromethane.4 The RSD5 threshold for 1,3-dichloropropene is the sum of its isomers (cis and trans).5 In earlier reports in this series, the NL-CA (0.005 μg/L) was used as the comparison threshold for 1,2,3-TCP.6 The MCL-CA thresholds for m- and p-Xylene and o-Xylene is the sum all three xylene compounds.
34 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table 3B. Pesticides and pesticide degradates, primary uses or sources, comparative thresholds, 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, threshold type, and threshold 

level as of November 17, 2008. Threshold type: 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 6A); na, 

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

Constituent 

(synonym or abbreviation)

Primary use 

or source

USGS 

parameter 

code

CAS 

number

 LRL 

(μg/L)

Threshold 

type 1

Threshold 

level 

(μg/L)

Detection

Acetochlor Herbicide 49260 34256-82-1 0.01 na na D

Alachlor Herbicide 46342 15972-60-8 0.008 MCL-US 2 —

Atrazine Herbicide 39632 1912-24-9 0.007 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 — 2

Carbaryl Insecticide 82680 63-25-2 0.2 RSD5-US 400 —

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

4-Chloro-2-methylphenol Herbicide degradate 61633 1570-64-5 0.0050 na na — 2

Chlorpyrifos Insecticide 38933 2921-88-2 0.01 HAL-US 2 —

Chlorpyrifos oxon Insecticide degradate 61636 5598-15-2 0.05 na na — 2

Cyfluthrin Insecticide 61585 68359-37-5 0.016 na na — 2

Cypermethrin Insecticide 61586 52315-07-8 0.02 na na — 2

Dacthal (DCPA) Herbicide 82682 1861-32-1 0.006 HAL-US 70 D

Deethylatrazine (2-Chloro-4-

isopropylamino-6-amino-s-triazine)

Herbicide degradate 04040 6190-65-4 0.014 na na D 2

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 HAL-US 1 —

3,4-Dichloroaniline Herbicide degradate 61625 95-76-1 0.004 na na D

Dichlorvos Insecticide 38775 62-73-7 0.02 na na — 2

Dicrotophos Insecticide 38454 141-66-2 0.08 na na —

Dieldrin Insecticide 39381 60-57-1 0.009 RSD5-US 0.02 —

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

Dimethoate Insecticide 82662 60-51-5 0.006 na na — 2

Ethion Insecticide 82346 563-12-2 0.012 na na — 2

Ethion monoxon Insecticide degradate 61644 17356-42-2 0.021 na na —

2-Ethyl-6-methylaniline Herbicide degradate 61620 24549-06-2 0.0049 na na —

Fenamiphos Insecticide 61591 22224-92-6 0.029 HAL-US 0.7 —

Fenamiphos sulfone Insecticide degradate 61645 31972-44-8 0.053 na na —

Fenamiphos sulfoxide Insecticide degradate 61646 31972-43-7 0.08 na na — 2

Fipronil Insecticide 62166 120068-37-3 0.04 na na —

Fipronil sulfide Insecticide degradate 62167 120067-83-6 0.013 na na D

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

Fonofos Insecticide 04095 944-22-9 0.01 HAL-US 10 —

Hexazinone Herbicide 04025 51235-04-2 0.008 HAL-US 400 — 2

Iprodione Fungicide 61593 36734-19-7 0.014 na na — 2

Isofenphos Insecticide 61594 25311-71-1 0.006 na na —

Malaoxon Insecticide degradate 61652 1634-78-2 0.08 na na —

Malathion Insecticide 39532 121-75-5 0.02 HAL-US 100 —

Table 3B. Pesticides and pesticide degradates, primary uses or sources, comparative thresholds, 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, threshold type, and threshold 

level as of November 17, 2008. Threshold type: 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 6A); na, 

not available; μg/L, micrograms per liter; —, not detected]
Tables 35

Table 3B. Pesticides and pesticide degradates, primary uses or sources, comparative thresholds, 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, threshold type, and threshold 

level as of November 17, 2008. Threshold type: 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 6A); na, 

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

Constituent 

(synonym or abbreviation)

Primary use 

or source

USGS 

parameter 

code

CAS 

number

 LRL 

(μg/L)

Threshold 

type 1

Threshold 

level 

(μg/L)

Detection

Metalaxyl Fungicide 61596 57837-19-1 0.0069 na na D

Methidathion Insecticide 61598 950-37-8 0.006 na na —

Metolachlor Herbicide 39415 51218-45-2 0.014 HAL-US 700 D

Metribuzin Herbicide 82630 21087-64-9 0.016 HAL-US 70 —

Myclobutanil Fungicide 61599 88671-89-0 0.01 na na —

1-Naphthol Insecticide degradate 49295 90-15-3 0.04 na na — 2

Paraoxon-methyl Insecticide degradate 61664 950-35-6 0.01 na na — 2

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 na na — 2

Phorate Insecticide 82664 298-02-2 0.02 na na — 2

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

Phosmet Insecticide 61601 732-11-6 0.2 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 0.0059 na na —

Pronamide (Propyzamide) Herbicide 82676 23950-58-5 0.004 RSD5-US 20 —

Simazine Herbicide 04035 122-34-9 0.01 MCL-US 4 D

Tebuthiuron Herbicide 82670 34014-18-1 0.02 HAL-US 500 —

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 na na —

Tribufos Defoliant 61610 78-48-8 0.035 na na — 2

Trifluralin Herbicide 82661 1582-09-8 0.012 HAL-US 10 —

1

 Maximum contaminant level thresholds 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 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.
36 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table 3C. Polar pesticides and metabolites, primary uses or sources, comparative thresholds, and reporting information for the U.S. 

Geological Survey (USGS) National Water Quality Laboratory Schedule 2060.—Continued

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

threshold type, and threshold level as of November 17, 2008. Threshold type: HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health 

advisory; 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; IRL, interim reporting level; 

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

Constituent 

(synonym or abbreviation)

Primary use 

or source

USGS 

parameter 

code

CAS 

number

 LRL 

(μg/L)

Threshold 

type 1

Threshold 

level 

(μg/L)

Detection

Acifluorfen Herbicide 49315 50594-66-6 0.04 na na — 2

Aldicarb Insecticide 49312 116-06-3 0.12 MCL-US 3 — 2

Aldicarb sulfone Degradate 49313 1646-88-4 0.08 MCL-US 3 — 2

Aldicarb sulfoxide Degradate 49314 1646-87-3 0.06 MCL-US 4 —

Atrazine Herbicide 39632 1912-24-9 0.04 MCL-CA 1 —

Bendiocarb Insecticide 50299 22781-23-3 0.04 na na —

Benomyl Fungicide 50300 17804-35-2 0.06 na na — 2

Bensulfuron-methyl Herbicide 61693 83055-99-6 0.06 na na —

Bentazon Herbicide 38711 25057-89-0 0.06 MCL-CA 18 —

Bromacil Herbicide 04029 314-40-9 0.02 HAL-US 70 D

Bromoxynil Herbicide 49311 1689-84-5 0.12 na na — 2

Caffeine Beverages 50305 58-08-2 0.08 na na —

Carbaryl Herbicide 49310 63-25-2 0.04 RSD5-US 400 —

Carbofuran Herbicide 49309 1563-66-2 0.04 MCL-CA 18 —

Chloramben, methyl ester Herbicide 61188 7286-84-2 0.10 na na —

Chlorimuron-ethyl Herbicide 50306 90982-32-4 0.08 na na —

3-(4-Chlorophenyl)-1-methyl urea Degradate 61692 5352-88-5 0.06 na na D 2

Clopyralid Herbicide 49305 1702-17-6 0.06 na na — 2

Cycloate Herbicide 04031 1134-23-2 0.04 na na —

2,4-D Herbicide 39732 298-00-0 0.02 HAL-US 70 —

2,4-D methyl ester Herbicide 50470 na 0.04 na na — 2

2,4-D plus 2,4-D methyl ester Herbicides 66496 na 2 0.02 na na —

2,4-DB (4-(2,4-Dichlorophenoxy)butyric 

acid)

Herbicide 38746 94-82-6 0.02 na na — 2

DCPA (Dacthal) monoacid Degradate 49304 887-54-7 0.04 na na —

Deethylatrazine (2-Chloro-4-

isopropylamino-6-amino-s-triazine)

Degradate 04040 6190-65-4 0.06 na na — 2

Deisopropyl atrazine (2-Chloro-6-

ethylamino-4-amino-s-triazine)

Degradate 04038 1007-28-9 0.06 na na —

Dicamba Herbicide 38442 1918-00-9 0.04 HAL-US 4,000 — 2

Dichlorprop Herbicide 49302 120-36-5 0.04 na na —

Dinoseb (Dinitrobutyl phenol) Herbicide 49301 88-85-7 0.04 MCL-CA 7 — 2

Diphenamid Herbicide 04033 957-51-7 0.04 HAL-US 200 —

Diuron Herbicide 49300 330-54-1 0.04 HAL-US 10 D

Fenuron Herbicide 49297 101-42-8 0.06 na na D

Flumetsulam Herbicide 61694 98967-40-9 0.06 na na —

Fluometuron Herbicide 38811 2164-17-2 0.04 HAL-US 90 —

Hydroxyatrazine (2-Hydroxy-4-

isopropylamino-6-ethylamino-striazine)

Degradate 50355 2163-68-0 0.06 na na —

Table 3C. Polar pesticides and metabolites, primary uses or sources, comparative thresholds, and reporting information for the U.S. 

Geological Survey (USGS) National Water Quality Laboratory Schedule 2060.

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

type, and threshold level as of November 17, 2008. Threshold type: HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory; 

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; IRL, interim reporting level; 

D, detected in groundwater samples (table 6B); na, not available; μg/L, micrograms per liter; —, not detected]
Tables 37

Table 3C. Polar pesticides and metabolites, primary uses or sources, comparative thresholds, and reporting information for the U.S. 

Geological Survey (USGS) National Water Quality Laboratory Schedule 2060.—Continued

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

threshold type, and threshold level as of November 17, 2008. Threshold type: HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health 

advisory; 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; IRL, interim reporting level; 

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

Constituent 

(synonym or abbreviation)

Primary use 

or source

USGS 

parameter 

code

CAS 

number

 LRL 

(μg/L)

Threshold 

type 1

Threshold 

level 

(μg/L)

Detection

3-Hydroxycarbofuran Degradate 49308 16655-82-6 0.04 na na —

Imazaquin Herbicide 50356 81335-37-7 0.06 na na —

Imazethapyr Herbicide 50407 81335-77-5 0.06 na na —

Imidacloprid Insecticide 61695 138261-41-3 0.06 na na —

Linuron Herbicide 38478 330-55-2 0.04 na na —

MCPA (2-Methyl-4-chlorophenoxyacetic 

acid) 

Herbicide 38482 94-74-6 0.04 HAL-US 30 —

MCPB (4-(2-Methyl-4-chlorophenoxy)

butyric acid)

Herbicide 38487 94-81-5 0.2 na na — 2

Metalaxyl Fungicide 50359 57837-19-1 0.04 na na —

Methiocarb Insecticide 38501 2032-65-7 0.04 na na —

Methomyl Insecticide 49296 16752-77-5 0.12 HAL-US 200 —

Metsulfuron methyl 3 Herbicide 61697 74223-64-6 3 0.14 na na —

Neburon Herbicide 49294 555-37-3 0.02 na na —

Nicosulfuron Herbicide 50364 111991-09-4 0.10 na na — 4

Norflurazon Herbicide 49293 27314-13-2 0.04 na na —

Oryzalin Herbicide 49292 19044-88-3 0.04 na na —

Oxamyl Insecticide 38866 23135-22-0 0.12 MCL-CA 50 —

Picloram Herbicide 49291 1918-02-01 0.12 MCL-US 500 — 2

Propham Herbicide 49236 122-42-9 0.04 HAL-US 100 —

Propiconazole Fungicide 50471 60207-90-1 0.04 na na —

Propoxur Insecticide 38538 114-26-1 0.06 na na —

Siduron Herbicide 38548 1982-49-6 0.04 na na —

Sulfometuron-methyl Herbicide 50337 74222-97-2 0.06 na na —

Tebuthiuron Herbicide 82670 34014-18-1 0.06 HAL-US 500 —

Terbacil Herbicide 04032 5902-51-2 0.04 HAL-US 90 —

Triclopyr Herbicide 49235 55335-06-3 0.08 na na —

1

 Maximum contaminant level thresholds 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 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

 Value is an IRL rather than an LRL

4

 The median laboratory matrix-spike recovery was greater than 130 percent. High recoveries may indicate that reported values could be higher than what is in 

the sample.
38 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table 3D. Pharmaceutical compounds, primary uses or sources, comparative thresholds, and reporting information for the U.S. 

Geological Survey (USGS) National Water Quality Laboratory Schedule 2080.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Abbreviations: CAS, Chemical Abstract Service; MDL, 

method detection limit; na, not available; μg/L, micrograms per liter]

Constituent Primary use or source

USGS 

parameter 

code

CAS 

number

MDL 1

(μg/L)

Threshold 

type

Threshold 

level 

(μg/L)

1,7-Dimethylxanthine Caffeine metabolite 62030 611-59-6 0.10 na na

Acetaminophen Analgesic 62000 103-90-2 0.60 na na

Albuterol Anti-inflammatory; bronchodilator 62020 18559-94-9 0.03 na na

Caffeine Stimulant 50305 58-08-2 0.40 na na

Carbamazapine Anticonvulsant; analgesic; mood stabilizer 62793 298-46-4 0.02 na na

Codeine Opioid narcotic 62003 76-57-3 0.02 na na

Cotinine Nicotine metabolite 62005 486-56-6 0.03 na na

Dehydronifedipine Antianginal metabolite 62004 67035-22-7 0.03 na na

Diltiazem Antianginal; antihypertensive 62008 42399-41-7 0.02 na na

Diphenhydramine Antihistamine 62796 58-73-1 0.03 na na

Sulfamethoxazole Antibacterial, antiprotozoal 62021 723-46-6 0.05 na na

Thiabendazole Anthelmintic 62801 148-79-8 0.02 na na

Trimethoprim Antibacterial 62023 738-70-5 0.01 na na

Warfarin Anticoagulant 62024 81-81-2 0.03 na na

1

 The California Groundwater Ambient Monitoring and Assessment (GAMA) program uses uses reporting limits for the pharmaceutical compounds that 

are more conservative than those recommended by the USGS National Water Quality Laboratory. For albuterol, carbamazepine, codeine, dehydronifedipine, 

diltiazem, sulfamethoxazole, thiabendazole, trimethoprim, and warfarin, the MDL corresponds to the long-term method detection limit determined by the USGS 

Branch of Quality Systems in October 2007 (BQS LT-MDL). For acetaminophen, caffeine, cotinine, diphenhydramine, and xanthine, the MDL corresponds 

to the study reporting levels determined from assessing quality-control data associated with GAMA samples collected from May 2004 through September 

2007 (GAMA SRL). The GAMA SRLs are higher than the BQS LT-MDL for those compounds. Concentrations reported by the USGS National Water Quality 

Laboratory that are lower than the BQS LT-MDL or GAMA SRL are reported as non-detections by the GAMA program. Results for pharmaceutical compounds 

from the GAMA SCRC study unit will be included in a subsequent report.
Tables 39

Constituent 

(synonym or abbreviation)

Primary use 

or source

USGS 

parameter 

code

CAS 

number

 MRL 

(μg/L)

Threshold 

type1

Threshold 

level 

(μg/L)

Detection

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

N-nitrosodimethylamine 

(NDMA)

Disinfection by-product 34438 62-75-9 0.002 NL-CA 0.010 —

1,2,3-TCP Fumigant, solvent 77443 96-18-4 0.005 HAL-US 40 —

1

 Maximum contaminant level thresholds 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.

Table 3E. Constituents of special interest (perchlorate, N-nitrosodimethylamine [NDMA], and 1,2,3-TCP), primary uses or sources, 

comparative thresholds, and reporting information for Weck Laboratories, Inc. analyses.

[The five-digit U.S. Geological Survey (USGS) parameter code is used to uniquely identify a specific constituent or property. Minimum reporting level, 

threshold type, and threshold level as of November 17, 2008. Threshold type: HAL-US, U.S. Environmental Protection Agency lifetime health advisory; 

MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; NL-CA, CDPH notification level. Other abbreviations: CAS, 

Chemical Abstract Service; MRL, minimum reporting level; D, detected in groundwater samples (table 7); μg/L, micrograms per liter; —, not detected]
40 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table 3F. Trace elements, comparative thresholds, 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, threshold type, and threshold 

level as of November 17, 2008. Threshold type: 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: BQS, USGS Office of Water Quality 

Branch of Quality Systems; CAS, Chemical Abstract Service; LRL, laboratory reporting level; SRL, study reporting limit; D, detected in groundwater samples 

(table 8); na, not available; μg/L, micrograms per liter]

Constituent

USGS 

parameter 

code

CAS 

number

 LRL/SRL1

(μg/L)

Threshold 

type 2

Threshold 

level 

(μg/L)

Detection

Aluminum 01106 7429-90-5 1 1.6 MCL-CA 1,000 D

Antimony 01095 7440-36-0 0.04 MCL-US 6 D

Arsenic 01000 7440-38-2 0.06 MCL-US 10 D

Barium 01005 7440-39-3 1 0.36 MCL-CA 1,000 D

Beryllium 01010 7440-41-7 0.02 MCL-US 4 D

Boron 01020 7440-42-8 4 NL-CA 1,000 D

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

Chromium 01030 7440-47-3 1 0.42 MCL-CA 50 D

Cobalt 01035 7440-48-4 0.02 na na D

Copper 01040 7440-50-8 1 1.7 AL-US 1,300 D

Iron 01046 7439-89-6 1 6 SMCL-CA 300 D

Lead 01049 7439-92-1 1 0.65 AL-US 15 D

Lithium 01130 7439-93-2 1 na na D

Manganese 01056 7439-96-5 1 0.2 SMCL-CA 50 D

Mercury 71890 7439-97-6 1 0.012 MCL-US 2 D

Molybdenum 01060 7439-98-7 0.02 HAL-US 40 D

Nickel 01065 7440-02-0 1 0.36 MCL-CA 100 D

Selenium 01145 7782-49-2 0.06 MCL-US 50 D

Silver 01075 7440-22-4 0.008 SMCL-CA 100 D

Strontium 01080 7440-24-6 0.8 HAL-US 4,000 D

Thallium 01057 7440-28-0 0.04 MCL-US 2 D

Tungsten 01155 7440-33-7 0.11 na na D

Uranium 22703 7440-61-1 0.006 MCL-US 30 D

Vanadium 01085 7440-62-2 1 0.11 NL-CA 50 D

Zinc 01090 7440-66-6 1 4.8 SMCL-CA 3 5,000 D

1

 Study reporting limit (SRL) defined based on examination of GAMA quality-control (QC) samples collected from May 2004 through January 2008 (Olsen 

and others, 2010). Values below SRL are reported as less than or equal to the value reported by the laboratory (≤). In the USGS National Water Information 

System database, the result is accompanied with the following comment: Result is < or = reported value, based on QC data (may include: field blanks, sourcesolution blanks, trip blanks, National Water Quality Laboratory (NWQL) set blanks, NWQL blank water certificates, and USGS BQS Blind Blank Program 

data).

2

 Maximum contaminant level thresholds 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.

3

 The secondary maximum contaminant level for zinc is listed as SMCL-CA since SMCLs established by CDPH are used in this report for all constituents 

that have SMCL-CA values.
Tables 41

Table 3G. Nutrients and dissolved organic carbon (DOC), comparative thresholds, and reporting information for the U.S. Geological 

Survey (USGS) National Water Quality Laboratory Schedules 2755 and 2702 and Laboratory Code 2612.

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

level as of November 17, 2008. Threshold type: HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory level; MCL-US, USEPA 

maximum contaminant level. Other abbreviations: CAS, Chemical Abstract Service; LRL, laboratory reporting level; D, detected in groundwater samples 

(table 9); na, not available; mg/L, milligrams per liter]

Constituent

USGS 

parameter 

code

CAS 

number

 LRL 

(mg/L)

Threshold 

type 1

Threshold 

level 

(mg/L)

Detection

Ammonia (as nitrogen) 00608 7664-41-7 0.02 HAL-US 2 24.7 D

Ammonia plus organic nitrogen 

(as nitrogen)

00623 na 0.1 na na D

Ammonia plus organic nitrogen 

(as nitrogen), unfiltered

00625 17778-88-0 0.1 na na D

Nitrate plus nitrite (as nitrogen) 00631 na 0.04 MCL-US 10 D

Nitrite (as nitrogen) 00613 14797-65-0 0.002 MCL-US 1 D

Total nitrogen (ammonia, nitrite, nitrate, 

organic nitrogen)

62854 17778-88-0 0.06 na na D

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

Phosphorus, (as phosphorus) 00666 7723-14-0 0.04 na na D

Phosphorus, (as phosphorus), unfiltered 00665 7723-14-0 0.040 na na D

Dissolved organic carbon (DOC) 00681 na 0.33 na na D

1

 Maximum contaminant level thresholds 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 HAL-US is 30 mg/L “as ammonia.” To facilitate comparison to the analytical results, we have converted and reported this HAL-US as 24.7 mg/L “as 

nitrogen.”
42 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Constituent

USGS 

parameter 

code

CAS number LRL 

(mg/L)

Threshold 

type 1

Threshold 

level 

(mg/L)

Detection

Bromide 71870 24959-67-9 0.02 na na D

Calcium 00915 7440-70-2 0.02 na na D

Chloride 00940 16887-00-6 0.12 SMCL-CA 2 250 (500) D

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

Iodide 71865 7553-56-2 0.002 na na D

Magnesium 00925 7439-95-4 0.012 na na D

Potassium 00935 7440-09-7 0.06 na na D

Silica (as SiO2) 00955 7631-86-9 0.02 na na D

Sodium 00930 7440-23-5 0.12 na na D

Sulfate 00945 14808-79-8 0.18 SMCL-CA 2 250 (500) D

Residue on evaporation (total 

dissolved solids, TDS)

70300 na 10 SMCL-CA 2 500 (1,000) D

Laboratory alkalinity (as CaCO3) 3 29801 na 1 na na D

1

 Maximum contaminant level thresholds 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 recommended SMCL-CA thresholds for chloride, sulfate, and TDS are listed with the upper SMCL-CA thresholds in parentheses.

3

 Laboratory alkalinity results are presented in table 4.

Table 3H. Major and minor ions, silica, total dissolved solids (TDS), and alkalinity, comparative thresholds, 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, threshold type, and threshold 

level as of November 17, 2008. Threshold type: MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; SMCL-CA, 

CDPH secondary maximum contaminant level. Other abbreviations: CAS, Chemical Abstract Service; LRL, laboratory reporting level; D, detected in 

groundwater samples (table 10); na, not available; mg/L, milligrams per liter; SiO2, silicon dioxide; CaCO3, calcium carbonate]

Constituent 

USGS 

parameter 

code

CAS number MDL 

(μg/L)

Threshold 

type 1

Threshold 

level 

(μg/L)

Detection

Arsenic (III) 99034 22569-72-8 1 na na D

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

Iron (II) 01047 7439-89-6 2 na na D

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

1

 Maximum contaminant level thresholds 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.

Table 3I. Arsenic and iron species, comparative thresholds, 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 constituents or property. Method detection limit, threshold type, and threshold level 

as of November 17, 2008. Threshold type: MCL-US, U.S. Environmental Protection Agency (USEPA) maximum contaminant level; SMCL-US, USEPA 

secondary maximum contaminant level. Other abbreviations: CAS, Chemical Abstract Service; MDL, method detection limit; na, not available; μg/L, 

micrograms per liter; D, detected in groundwater samples (table 11)]
Tables 43

Constituent

USGS 

parameter 

code

CAS 

number

Reporting 

level 

type

Reporting 

level or 

uncertainty

Threshold 

type 1

Threshold 

level Detection

Stable isotope ratios (per mil)

δ2H in water 2 82082 na MU 2 na na D

δ18O in water 2 82085 na MU 0.20 na na D

δ15N in dissolved nitrate 2 82690 na MU 0.50 na na D

δ18O in dissolved nitrate 2 63041 na MU 1.00 na na D

δ34S in dissolved sulfate 2 49932 na MRL 0.4 na na na

δ13C in dissolved inorganic carbon 3 82081 na 1-sigma 0.05 na na D

Radioactive constituents (percent modern)

Carbon-14 3 49933 14762-75-5 1-sigma 0.002 na na D

Radioactive constituents (pCi/L)

Tritium 4 07000 10028-17-8 MRL 1 MCL-CA 20,000 D

Gross alpha radioactivity, 72-hour and 30-day 

counts 5

99920, 99921 12587-46-1 ssLC CSU MCL-US 15 D

Gross beta radioactivity, 72-hour and 30-day 

counts 5

99922, 99923 12587-47-2 ssLC CSU MCL-CA 50 D

1

 Maximum contaminant level thresholds 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

 USGS Stable Isotope Laboratory, Reston, Virginia.

3

 Woods Hole Oceanographic Institution, National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS) (contract laboratory).

4

 USGS Stable Isotope and Tritium Laboratory, Menlo Park, California.

5

 Eberline Analytical Services (contract laboratory).

Table 3J. Isotopic and radioactive constituents, comparative thresholds, 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. 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. Threshold 

type and threshold level as of November 17, 2008. Threshold type: MCL-CA, California Department of Public Health maximum contaminant level; MCL-US, 

U.S. Environmental Protection Agency maximum contaminant level. Other abbreviations: CAS, Chemical Abstract Service; CSU, combined standard 

uncertainty; ssLC, sample-specific critical level; MRL, minimum reporting level; MU, method uncertainty; na, not available; pCi/L, picocuries per liter; 

D, detected in groundwater samples (tables 12 and 14)]
44 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Constituent

USGS 

parameter 

code

CAS number MU 

(percent)

Reporting 

units

Threshold 

type 1

Threshold 

value 

(pCi/L)

Detection

Dissolved gases 2

Methane 76994 74-82-8 na μg/L na na D

Carbon dioxide 00405 124-39-9 na mg/L na na D

Nitrogen 00597 7727-37-9 na mg/L na na D

Oxygen 62971 7782-44-7 na mg/L na na D

Argon 82043 7440-37-1 na mg/L na na D

Dissolved noble gases 3

Helium-3 / Helium-4 61040 na / 7440-59-7 0.75 atom ratio na na na

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

Helium-4 85561 7440-59-7 2 cm3 STP/g na na na

Krypton 85565 7439-90-9 2 cm3 STP/g na na na

Neon 61046 7440-01-09 2 cm3 STP/g na na na

Xenon 85567 7440-63-3 2 cm3 STP/g na na na

Tritium 07000 10028-17-8 1 pCi/L MCL-CA 20,000 na

1

 Maximum contaminant level thresholds 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

 USGS Chlorofluorocarbon Laboratory, Reston, Virginia.

3

 Lawrence Livermore National Laboratory.

Table 3K. Dissolved gases and tritium, comparison thresholds and reporting information for the U.S. Geological Survey (USGS)

Chlorofluorocarbon Laboratory and Lawrence Livermore National Laboratory analyses.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Threshold type and threshold value as of November 17, 

2008. Threshold type: MCL-CA, California Department of Public Health maximum contaminant level. Other abbreviations: CAS, Chemical Abstract Service; 

MU, method uncertainty; μg/L, micrograms per liter; mg/L, milligrams per liter; na, not available; pCi/L, picocuries per liter; cm3 STP/g, cubic centimeters of 

gas at standard temperature and pressure per gram of water; D, detected in groundwater samples (table 13)]
Tables 45

Table 4. Field water-quality indicators in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Threshold type and threshold level as of November 17, 2008. Threshold 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, degree Celsius; mg/L, milligrams per liter; nc, not collected; na, not available; NTRU, nephelometric turbidity unit; RL, reporting limit or range; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium carbonate; *, value above threshold level; **, value above upper threshold level; —, not detected]

GAMA 

identification

number

Turbidity, 

field 

(NTRU) 

(63676)

Dissolved 

oxygen,

 field 

(mg/L) 

(00300) 

Water 

temperature, 

field 

(degrees C) 

(00010)

pH, lab 

(standard 

units) 

(00403)

pH, field 

(standard 

units) 

(00400)

Specific 

conductance, 

lab 

(μS/cm at 25oC) 

(90095)

Specific 

conductance, 

field 

(μS/cm at 25oC) 

(00095)

Alkalinity, 

lab 

(mg/L as 

CaCO3) 

(29801)

Alkalinity, 

field 

(mg/L as

 CaCO3) 

(29802)

Bicarbonate, 

field 

(mg/L) 

(63786)

Bicarbonate 1

(mg/L)

Carbonate, 

field 

(mg/L) 

(63788)

Carbonate 1

(mg/L)

Threshold type SMCL-CA na na SMCL-US SMCL-US SMCL-CA SMCL-CA na na na na na naThreshold level 2 5 na na <6.5 or> 8.5 <6.5 or >8.5 3 900 (1,600) 3 900 (1,600) na na na na na na[RL] [0.1] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [1] [1] [1] [1] [1] [1]

SCRC Grid wells (55 wells sampled)

SCRC-B01 nc 0.2 18.5 nc 7.1 nc *1,020 nc nc nc nc nc ncSCRC-B02 nc 2.5 18.5 nc 7.8 nc 792 nc nc nc nc nc ncSCRC-B03 nc 9.4 18.5 nc 7.9 nc *1,340 nc nc nc nc nc ncSCRC-B04 nc 0.8 21.0 nc 7.1 nc *1,200 nc nc nc nc nc ncSCRC-B05 0.3 nc 18.5 7.6 7.4 *1,170 *1,160 191 178 217 233 0.2 0.4SCRC-B06 nc 9.8 22.5 nc 7.2 nc *921 nc nc nc nc nc ncSCRC-B07 nc 6.6 19.0 nc 6.6 nc 675 nc nc nc nc nc ncSCRC-B08 0.1 0.7 20.5 7.5 7.2 *1,170 *1,180 322 317 385 392 1.0 0.5SCRC-B09 nc 8.7 20.0 nc 7.5 nc 843 nc nc nc nc nc ncSCRC-B10 0.4 1.9 18.5 6.8 *6.2 673 667 84 77 94 102 — 0.0SCRC-B11 0.2 2.1 18.5 7.2 7.1 *1,500 *1,490 319 315 383 389 0.5 0.3SCRC-B12 nc 5.1 19.5 nc 7.2 nc *1,380 nc nc nc nc nc ncSCRC-B13 nc 5.2 21.5 nc 7.4 nc 898 nc nc nc nc nc ncSCRC-B14 nc nc 19.0 nc 7.3 nc *1,520 nc nc nc nc nc ncSCRC-B15 nc nc 17.5 nc 7.4 nc *1,460 nc nc nc nc nc ncSCRC-B16 0.3 nc 18.5 7.5 7.1 **1,710 **1,710 239 230 280 290 0.5 0.5SCRC-B17 nc nc 16.5 nc 7.3 nc *1,110 nc nc nc nc nc ncSCRC-B18 nc 5.4 17.5 nc 7.2 nc *1,150 nc nc nc nc nc ncSCRC-B19 nc 5.6 17.5 nc 7.2 nc *1,100 nc nc nc nc nc ncSCRC-B20 nc 2.8 19.0 nc 7.0 nc *1,240 nc nc nc nc nc nc

Table 4. Field water-quality indicators in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.[The five-digit U.S. Geological Survey (USGS) parameter code below the constituent name is used to uniquely identify a specific constituent or property. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Threshold type and threshold level as of November 17, 2008. Threshold 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, degree Celsius; mg/L, milligrams per liter; nc, not collected; na, not available; NTRU, nephelometric turbidity unit; RL, reporting limit or range; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium carbonate; *, value above threshold level; **, value above upper threshold level; —, not detected]
46 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table 4. Field water-quality indicators in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Threshold type and threshold level as of November 17, 2008. Threshold 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, degree Celsius; mg/L, milligrams per liter; nc, not collected; na, not available; NTRU, nephelometric turbidity unit; RL, reporting limit or range; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium carbonate; *, value above threshold level; **, value above upper threshold level; —, not detected] GAMA identification number Turbidity, field (NTRU) (63676) Dissolved oxygen, field (mg/L) (00300) Water temperature, field (degrees C) (00010) pH, lab (standard units) (00403) pH, field (standard units) (00400) Specific conductance, lab (μS/cm at 25oC) (90095) Specific conductance, field (μS/cm at 25oC) (00095) Alkalinity, lab (mg/L as CaCO3) (29801) Alkalinity, field (mg/L as CaCO3) (29802) Bi- carbonate, field (mg/L) (63786) Bi- carbonate 1 (mg/L) Carbonate, field (mg/L) (63788) Carbonate 1 (mg/L) Threshold type SMCL-CA na na SMCL-US SMCL-US SMCL-CA SMCL-CA na na na na na na Threshold level 2 5 na na <6.5 or> 8.5 <6.5 or >8.5 3 900 (1,600) 3 900 (1,600) na na na na na na [RL] [0.1] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [1] [1] [1] [1] [1] [1] SCRC-B21 0.4 0.2 16.5 7.3 7.1 **2,550 **2,570 405 394 479 493 0.6 0.5 SCRC-B22 0.6 3.6 18.0 7.3 7.1 **2,120 **2,120 284 269 327 346 0.3 0.4 SCRC-B23 nc 4.8 23.5 7.3 7.2 *983 *968 165 144 176 200 0.2 0.2 SCRC-B24 nc 5.8 20.0 nc 7.3 nc 895 nc nc nc nc nc nc SCRC-B25 nc 0.5 18.0 nc 7.2 nc *1,150 nc 224 273 nc 0.2 nc SCRC-B26 nc <0.2 18.5 7.4 7.2 **2,490 **2,540 450 427 528 547 0.7 0.6 SCRC-B27 0.3 4.3 21.0 7.5 7.2 *1,020 *1,010 151 144 175 183 0.2 0.2 SCRC-B28 0.4 6.5 21.0 7.1 6.5 409 404 37 34 41 45

— 0.0

SCRC-B29 nc <0.2 20.5 nc *5.8 nc *1,270 nc nc nc nc nc ncSCRC-B30 0.4 8.0 17.0 7.6 7.3 *1,150 *1,150 204 198 241 248 0.4 0.4SCRC-B31 nc 2.0 21.0 nc 7.2 nc *1,290 nc nc nc nc nc ncSCRC-B32 nc 4.2 17.0 nc 7.1 nc **2,390 nc nc nc nc nc ncSCRC-B33 nc 3.7 22.0 nc 6.9 nc 685 nc nc nc nc nc ncSCRC-B34 0.5 0.2 22.5 7.3 7.1 *1,250 *1,280 261 256 312 318 0.3 0.3SCRC-B35 nc 0.7 18.0 nc 7.0 nc **2,110 nc nc nc nc nc ncSCRC-B36 0.2 8.5 17.0 7.5 7.3 *1,080 *1,050 190 185 224 231 0.3 0.3SCRC-B37 0.2 0.3 20.5 7.3 7.2 *1,550 *1,560 328 323 392 399 0.6 0.4SCRC-B38 nc 7.1 20.0 nc 7.3 nc 851 nc nc nc nc nc ncSCRC-B39 0.1 4.1 17.5 6.7 7.2 *1,060 *1,050 215 206 251 263 0.4 0.1SCRC-H01 0.1 0.2 22.5 7.7 7.6 683 682 165 149 181 200 0.2 0.4SCRC-H02 0.1 6.2 14.0 7.6 7.5 *1,120 *1,110 350 334 405 425 1.0 0.7SCRC-H03 0.5 0.5 22.0 6.8 6.6 552 555 163 150 183 198 0.1 0.1
Tables 47

Table 4. Field water-quality indicators in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Threshold type and threshold level as of November 17, 2008. Threshold 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, degree Celsius; mg/L, milligrams per liter; nc, not collected; na, not available; NTRU, nephelometric turbidity unit; RL, reporting limit or range; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium carbonate; *, value above threshold level; **, value above upper threshold level; —, not detected]

GAMA 

identification

number

Turbidity, 

field 

(NTRU) 

(63676)

Dissolved 

oxygen,

 field 

(mg/L) 

(00300) 

Water 

temperature, 

field 

(degrees C) 

(00010)

pH, lab 

(standard 

units) 

(00403)

pH, field 

(standard 

units) 

(00400)

Specific 

conductance, 

lab 

(μS/cm at 25oC) 

(90095)

Specific 

conductance, 

field 

(μS/cm at 25oC) 

(00095)

Alkalinity, 

lab 

(mg/L as 

CaCO3) 

(29801)

Alkalinity, 

field 

(mg/L as

 CaCO3) 

(29802)

Bicarbonate, 

field 

(mg/L) 

(63786)

Bicarbonate 1

(mg/L)

Carbonate, 

field 

(mg/L) 

(63788)

Carbonate 1

(mg/L)

Threshold type SMCL-CA na na SMCL-US SMCL-US SMCL-CA SMCL-CA na na na na na naThreshold level 2 5 na na <6.5 or> 8.5 <6.5 or >8.5 3 900 (1,600) 3 900 (1,600) na na na na na na[RL] [0.1] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [1] [1] [1] [1] [1] [1]SCRC-H04 0.4 0.3 23.5 7.4 7.2 *1,260 *1,260 359 350 425 437 0.7 0.5SCRC-H05 0.2 4.6 24.0 7.7 7.6 653 660 264 251 304 320 0.9 0.7SCRC-H06 0.6 4.4 22.5 6.9 6.8 659 661 96 90 110 117 — 0.0SCRC-H07 0.6 0.6 21.5 6.9 6.7 827 827 171 168 205 209 0.1 0.1SCRC-H08 0.2 1.1 28.0 7.6 7.4 *946 *964 373 369 448 454 1.1 0.8SCRC-H09 0.2 1.8 21.5 7.3 7.1 786 787 194 157 191 236 0.2 0.2SCRC-H10 0.4 1.3 21.0 7.2 7.5 *1,100 *1,010 319 4 307 4 374 389 4 0.3 0.3SCRC-H11 0.4 0.9 21.0 7.3 7.2 849 853 289 275 334 351 0.4 0.3SCRC-H12 0.1 0.5 24.0 7.2 6.9 *1,060 *1,070 238 224 273 289 0.2 0.2SCRC-H13 0.3 2.7 24.0 7.1 6.8 457 465 86 82 100 105 — 0.1SCRC-H14 1.7 0.7 20.0 7.4 7.2 *1,030 *1,030 345 359 436 419 0.6 0.4SCRC-H15 0.3 1.0 25.0 7.4 7.0 *911 *934 272 245 298 331 0.2 0.3SCRC-H16 0.2 nc 26.0 7.2 7.2 899 *915 380 366 445 463 0.6 0.3

SCRC Surface-water sites (3 sites sampled)

SCRC-SW1 *27.0 10.1 18.0 8.3 8.3 **1,720 **1,730 nc nc nc nc nc ncSCRC-SW2 *140 7.3 20.5 7.8 7.8 **1,680 **1,730 233 nc nc 282 nc 0.9SCRC-SW3 *7.1 7.8 19.5 7.8 7.6 **1,850 **1,830 157 nc nc 191 nc 0.6
48 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table 4. Field water-quality indicators in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Threshold type and threshold level as of November 17, 2008. Threshold 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, degree Celsius; mg/L, milligrams per liter; nc, not collected; na, not available; NTRU, nephelometric turbidity unit; RL, reporting limit or range; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium carbonate; *, value above threshold level; **, value above upper threshold level; —, not detected] GAMA identification number Turbidity, field (NTRU) (63676) Dissolved oxygen, field (mg/L) (00300) Water temperature, field (degrees C) (00010) pH, lab (standard units) (00403) pH, field (standard units) (00400) Specific conductance, lab (μS/cm at 25oC) (90095) Specific conductance, field (μS/cm at 25oC) (00095) Alkalinity, lab (mg/L as CaCO3) (29801) Alkalinity, field (mg/L as CaCO3) (29802) Bi- carbonate, field (mg/L) (63786) Bi- carbonate 1 (mg/L) Carbonate, field (mg/L) (63788) Carbonate 1 (mg/L) Threshold type SMCL-CA na na SMCL-US SMCL-US SMCL-CA SMCL-CA na na na na na na Threshold level 2 5 na na <6.5 or> 8.5 <6.5 or >8.5 3 900 (1,600) 3 900 (1,600) na na na na na na [RL] [0.1] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [1] [1] [1] [1] [1] [1] SCRC Understanding wells (15 wells sampled) SCRC-U01 nc 0.3 19.0 nc 7.3 nc **2,090 nc nc nc nc nc nc SCRC-U02 nc 0.6 18.5 nc 7.2 nc **2,320 nc nc nc nc nc nc SCRC-U03 0.1 0.8 18.5 7.3 7.1 *1,580 *1,580 294 283 344 358 0.3 0.3 SCRC-U04 nc 1.7 18.0 nc 7.0 nc **2,310 nc nc nc nc nc nc SCRC-U05 nc 9.1 18.5 nc 6.7 nc 168 nc nc nc nc nc nc SCRC-U06 0.2 5.2 22.0 7.6 7.3 *920 *923 141 125 153 172 0.1 0.3 SCRC-U07 0.8 7.5 16.0 7.0 7.2 **2,010 **2,020 245 238 289 299 0.4 0.1 SCRC-U08 1.1 7.2 15.0 7.7 7.4 781 779 178 172 208 216 0.8 0.5 SCRC-U09 0.2 5.9 18.5 7.4 7.2 **1,780 **1,790 222 216 263 270 0.3 0.3 SCRC-U10 0.1 7.6 16.5 7.3 7.1 **1,820 **1,850 211 206 250 257 0.3 0.3 SCRC-U11 nc 0.5 14.5 nc *6.2 nc **3,570 nc nc nc nc nc nc SCRC-U12 nc 4.6 18.5 nc *6.0 nc *1,430 nc nc nc nc nc nc SCRC-U13 nc <0.2 18.0 nc 7.0 nc 369 nc nc nc nc nc nc SCRC-U14 nc 0.3 15.5 nc 7.0 nc 874 nc nc nc nc nc nc SCRC-U15 nc 1.3 17.5 6.5 *6.1 286 286 29 25 31 35

— 0.0

1 Bicarbonate and carbonate concentrations were calculated from the laboratory 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 pK

W = 14.

2 The SMCL-CA for turbidity pertains only to surface-water samples.3 The SMCL-CA for specific conductance has recommended and upper threshold values. The upper value is shown in parentheses.4 Alkalinity, bicarbonate, and carbonate values generated by the incremental titration method (USGS parameter codes: 39086, 00453, and 00452, respectively).
Tables 49

Table 5. Volatile organic compounds (VOC) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 70 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 55 grid wells. All analytes are listed in table 3A. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, Understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; NL-CA, CDPH notification level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; μg/L, micrograms per liter; na, not available; —, not detected; *, value above threshold level]

Primary use or source Trihalomethane Solvent Refrigerant Gasoline Fumigant Solvent Gasoline Solvent

GAMA 

identification

number

Chloroform

 (Trichloromethane) 

(μg/L) 

(32106)

Perchloroethene 

(PCE, Tetrachloroethene) 

(μg/L) 

(34475)

Dichlorodifluoromethane 

(CFC-12) 

(μg/L) 

(34668)

Trichlorofluoromethane 

(CFC-11) 

(μg/L) 

(34488)

Toluene 

(μg/L) 

(34010)

1,2-Dichloropropane 

(μg/L) 

(34541)

Methylene 

chloride 

(Dichloromethane)

(μg/L) 

(34423)

Methyl 

tert-butyl 

ether 

(MTBE) 

(μg/L) 

(78032)

Tetrahydrofuran 

(μg/L) 

(81607)

Threshold type 1 MCL-US MCL-US NL-CA MCL-CA MCL-CA MCL-US MCL-US MCL-CA naThreshold level 2 80 5 1,000 150 150 5 5 13 na[LRL] [0.04] [0.04] [0.1] [0.08] [0.018] [0.02] [0.04] [0.1] [1.4]

SCRC Grid wells (55 wells sampled)

Number of wells with 

detections

10 7 6 4 2 1 1 1 1

Detection frequency (percent) 18.2 12.7 10.9 7.3 3.6 1.8 1.8 1.8 1.8

SCRC Basins study area (39 grid wells sampled)

SCRC-B01 0.1 — — — — — — — —SCRC-B02 — — — — — — — — —SCRC-B03 — E0.05 E0.06 E0.04 — — — — —SCRC-B05 E0.02 — — — 0.36 — — — —SCRC-B09 — — — — — — — — —SCRC-B10 — — — — V0.02 — — — —SCRC-B12 E0.05 E0.03 E0.25 — V0.03 — — — —SCRC-B13 — — — — — — — — —SCRC-B14 — E0.04 E0.12 E0.09 — — — — —SCRC-B15 — 0.71 E0.56 E0.08 — — — — —SCRC-B16 — 0.16 E0.21 0.16 — — — — —SCRC-B17 — — — — — — — — —SCRC-B19 — — — — — — — — —SCRC-B21 — — — — — E0.05 — — —SCRC-B22 E0.02 0.14 E0.14 — — — — — —

Table 5. Volatile organic compounds (VOC) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.[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 70 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 55 grid wells. All analytes are listed in table 3A. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, Understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; NL-CA, CDPH notification level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; μg/L, micrograms per liter; na, not available; —, not detected; *, value above threshold level]
50 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table 5. Volatile organic compounds (VOC) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 70 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 55 grid wells. All analytes are listed in table 3A. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, Understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; NL-CA, CDPH notification level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; μg/L, micrograms per liter; na, not available; —, not detected; *, value above threshold level] Primary use or source Trihalomethane Solvent Refrigerant Gasoline Fumigant Solvent Gasoline Solvent GAMA identification number Chloroform (Trichloro- methane) (μg/L) (32106) Perchloro- ethene (PCE, Tetra- chloroethene) (μg/L) (34475) Dichloro- difluoro- methane (CFC-12) (μg/L) (34668) Trichloro- fluoro- methane (CFC-11) (μg/L) (34488) Toluene (μg/L) (34010) 1,2-Di- chloro- propane (μg/L) (34541) Methylene chloride (Dichloro- methane) (μg/L) (34423) Methyl tert-butyl ether (MTBE) (μg/L) (78032) Tetra- hydrofuran (μg/L) (81607) Threshold type 1 MCL-US MCL-US NL-CA MCL-CA MCL-CA MCL-US MCL-US MCL-CA na Threshold level 2 80 5 1,000 150 150 5 5 13 na [LRL] [0.04] [0.04] [0.1] [0.08] [0.018] [0.02] [0.04] [0.1] [1.4] SCRC-B23 E0.04

—

—

—

—

—

—

— 3

SCRC-B25

— E0.06

—

—

—

—

—

—

—

SCRC-B27

—

—

—

—

—

—

—

—

—

SCRC-B28 0.11

—

—

—

—

— E0.03

—

—

SCRC-B29

—

—

—

—

—

—

— E0.1

—

SCRC-B32

—

—

—

—

—

—

—

—

—

SCRC-B33

—

—

—

—

—

—

—

—

—

Number of wells with 

detections

6 7 6 4 1 1 1 1 1

Detection frequency (percent) 15.3 17.9 15.3 10.2 2.6 2.6 2.6 2.6 2.6

SCRC Uplands study area (16 grid wells sampled)

SCRC-H02 E0.02

—

—

—

—

—

—

—

—

SCRC-H03 E0.05

—

—

—

—

—

—

—

—

SCRC-H06 E0.04

—

—

—

—

—

—

—

—

SCRC-H11 0.14

—

—

—

—

—

—

—

—

SCRC-H14

—

—

—

— 0.32

—

—

—

—

Number of wells with 

detections

4 0 0 0 1 0 0 0 0

Detection frequency (percent) 25.0 0 0 0 6 0 0 0 0
Tables 51

Table 5. Volatile organic compounds (VOC) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 70 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 55 grid wells. All analytes are listed in table 3A. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, Understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; NL-CA, CDPH notification level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; μg/L, micrograms per liter; na, not available; —, not detected; *, value above threshold level]

Primary use or source Trihalomethane Solvent Refrigerant Gasoline Fumigant Solvent Gasoline Solvent

GAMA 

identification

number

Chloroform

 (Trichloromethane) 

(μg/L) 

(32106)

Perchloroethene 

(PCE, Tetrachloroethene) 

(μg/L) 

(34475)

Dichlorodifluoromethane 

(CFC-12) 

(μg/L) 

(34668)

Trichlorofluoromethane 

(CFC-11) 

(μg/L) 

(34488)

Toluene 

(μg/L) 

(34010)

1,2-Dichloropropane 

(μg/L) 

(34541)

Methylene 

chloride 

(Dichloromethane)

(μg/L) 

(34423)

Methyl 

tert-butyl 

ether 

(MTBE) 

(μg/L) 

(78032)

Tetrahydrofuran 

(μg/L) 

(81607)

Threshold type 1 MCL-US MCL-US NL-CA MCL-CA MCL-CA MCL-US MCL-US MCL-CA naThreshold level 2 80 5 1,000 150 150 5 5 13 na[LRL] [0.04] [0.04] [0.1] [0.08] [0.018] [0.02] [0.04] [0.1] [1.4]

SCRC Understanding wells 3 (15 wells sampled)

SCRC-U04 — — — — — — — — —SCRC-U07 — — — — — — — — —SCRC-U11 — — — — — — — — —SCRC-U12 — — — — — — — — —SCRC-U14 E0.04 — — — — — — — —
52 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table 5. Volatile organic compounds (VOC) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 70 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 55 grid wells. All analytes are listed in table 3A. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, Understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; NL-CA, CDPH notification level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; μg/L, micrograms per liter; na, not available; —, not detected; *, value above threshold level] Primary use or source Organic synthesis Solvent Organic synthesis Gasoline Detections per well Any VOC GAMA identification number 1,1-Di- chloroethene (1,1-DCE) (μg/L) (34501) cis-1,2-Dichloro- ethene 

(cis-1,2-DCE) (μg/L) 

(77093)

trans-1,2-

Dichloroethene 

(trans-1,2-DCE) 

(μg/L) 

(34546)

Trichloroethene 

(TCE) 

(μg/L) 

(39180)

Vinyl 

chloride 

(Chloroethene) 

(μg/L) 

(39175)

1,2,4-Trimethylbenzene 

(μg/L) 

(77222)

Threshold type 1 MCL-CA MCL-CA MCL-CA MCL-US MCL-CA NL-CAThreshold level 6 6 10 5 0.5 330

[LRL] [0.02] [0.02] [0.018] [0.02] [0.08] [0.04]

SCRC Grid wells (55 wells sampled)

Number of wells with 

detections

0 0 0 0 0 0 18

Detection frequency (percent) 0 0 0 0 0 0 33Total Detections 33

SCRC Basins study area (39 grid wells sampled)

SCRC-B01

—

—

—

—

— V0.09 1

SCRC-B02

—

—

—

—

— V0.08 0

SCRC-B03

—

—

—

—

— V0.10 3

SCRC-B05

—

—

—

—

—

— 2

SCRC-B09

—

—

—

—

— V0.09 0

SCRC-B10

—

—

—

—

—

— 0

SCRC-B12

—

—

—

—

— V0.04 3

SCRC-B13

—

—

—

—

— V0.03 0

SCRC-B14

—

—

—

—

— V0.06 3

SCRC-B15

—

—

—

—

— V0.12 3

SCRC-B16

—

—

—

—

—

— 3

SCRC-B17

—

—

—

—

— V0.10 0

SCRC-B19

—

—

—

—

— V0.06 0

SCRC-B21

—

—

—

—

—

— 1

SCRC-B22

—

—

—

—

—

— 3
Tables 53

Table 5. Volatile organic compounds (VOC) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 70 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 55 grid wells. All analytes are listed in table 3A. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, Understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type:MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; NL-CA, CDPH notification level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; μg/L, micrograms per liter; na, not available; —, not detected; *, value above threshold level]

Primary use or source Organic synthesis Solvent Organic synthesis Gasoline

Detections 

per well Any VOC GAMA identification

number

1,1-Dichloroethene 

(1,1-DCE) 

(μg/L) 

(34501)

cis-1,2-Dichloroethene 

(cis-1,2-DCE) (μg/L) 

(77093)

trans-1,2-

Dichloroethene 

(trans-1,2-DCE) 

(μg/L) 

(34546)

Trichloroethene 

(TCE) 

(μg/L) 

(39180)

Vinyl 

chloride 

(Chloroethene) 

(μg/L) 

(39175)

1,2,4-Trimethylbenzene 

(μg/L) 

(77222)

Threshold type 1 MCL-CA MCL-CA MCL-CA MCL-US MCL-CA NL-CAThreshold level 6 6 10 5 0.5 330

[LRL] [0.02] [0.02] [0.018] [0.02] [0.08] [0.04]SCRC-B23 — — — — — — 2SCRC-B25 — — — — — V0.17 1SCRC-B27 — — — — — V0.07 0SCRC-B28 — — — — — V0.03 2SCRC-B29 — — — — — — 1SCRC-B32 — — — — — V0.04 0SCRC-B33 — — — — — V0.08 0Number of wells with 

detections

0 0 0 0 0 0 13

Detection frequency (percent) 0 0 0 0 0 0 33Total Detections 28

SCRC Uplands study area (16 grid wells sampled)

SCRC-H02 — — — — — — 1SCRC-H03 — — — — — — 1SCRC-H06 — — — — — — 1SCRC-H11 — — — — — — 1SCRC-H14 — — — — — — 1Number of wells with 

detections

0 0 0 0 0 0 5

Detection frequency (percent) 0 0 0 0 0 0 31Total Detections 5
54 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table 5. Volatile organic compounds (VOC) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 70 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 55 grid wells. All analytes are listed in table 3A. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, Understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; NL-CA, CDPH notification level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; μg/L, micrograms per liter; na, not available; —, not detected; *, value above threshold level] Primary use or source Organic synthesis Solvent Organic synthesis Gasoline Detections per well Any VOC GAMA identification number 1,1-Di- chloroethene (1,1-DCE) (μg/L) (34501) cis-1,2-Dichloro- ethene 

(cis-1,2-DCE) (μg/L) 

(77093)

trans-1,2-

Dichloroethene 

(trans-1,2-DCE) 

(μg/L) 

(34546)

Trichloroethene 

(TCE) 

(μg/L) 

(39180)

Vinyl 

chloride 

(Chloroethene) 

(μg/L) 

(39175)

1,2,4-Trimethylbenzene 

(μg/L) 

(77222)

Threshold type 1 MCL-CA MCL-CA MCL-CA MCL-US MCL-CA NL-CAThreshold level 6 6 10 5 0.5 330

[LRL] [0.02] [0.02] [0.018] [0.02] [0.08] [0.04]

SCRC Understanding wells 3 (15 wells sampled)

SCRC-U04

—

—

—

—

— V0.07 0

SCRC-U07

—

—

—

—

— V0.12 0

SCRC-U11 E0.06 *16.3 0.21 0.69 *1.2

— 5

SCRC-U12

—

—

—

—

— V0.07 0

SCRC-U14

—

—

—

—

—

— 1

1Maximum contaminant level thresholds 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.2The MCL-US threshold for trihalomethanes is for the sum of chloroform, bromoform, bromodichloromethane, and dibromochloromethane.3Understanding wells were not included in statistical calculations.
Tables 55

Table 6A. Pesticides and pesticide degradates detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 69 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 54 grid wells sampled. All analytes are listed in table 3B. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. Environmental Protection Agency maximum contaminant level; HAL-US, U.S. Environmental Protection Agency lifetime health advisory 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; μg/L, microgram per liter; na, not available; —, not detected]

Primary use 

or source

Herbicide 

degradate Herbicide Fungicide Herbicide degradate Herbicide Insecticide degradate Herbicide

Pesticide 

detections 

per well

Any 

pesticide GAMA 

identification 

number

Deethylatrazine 

(2-Chloro4-isopropylamino6-amino-s-triazine) 

(μg/L) (04040)

Atrazine 

(μg/L) 

(39632)

Simazine 

(μg/L) 

(04035)

Metolachlor 

(μg/L) 

(39415)

Metalaxyl 

(μg/L) 

(61596)

3,4-Dichloroaniline 

(μg/L) 

(61625)

Acetochlor 

(μg/L) 

(49260)

Fipronil 

sulfide 

(μg/L) 

(62167)

Fipronil 

sulfone 

(μg/L) 

(62168)

Prometon 

(μg/L) 

(04037)

Dacthal 

(DCPA) 

(μg/L) 

(82682)

Threshold type 1 na MCL-CA MCL-US HAL-US na na na na HAL-US HAL-US HAL-USThreshold level na 1 4 700 na na na na 100 100 70[LRL] [0.014] [0.007] [0.01] [0.014] [0.0069] [0.004] [0.01] [0.013] [0.024] [0.02] [0.007]

SCRC Grid wells (54 wells sampled) 2

Number of 

wells with detections

10 5 3 2 1 1 1 1 1 0 0 15

Detection 

frequency (percent)

18.5 9.3 5.6 3.7 1.9 1.9 1.9 1.9 1.9 0 0 28

Total Detections 25

SCRC Basins Study Area (38 grid wells sampled) 2

SCRC-B01 — — — E0.007 — — — — — — — 1SCRC-B03 E0.021 0.009 — — — — — — — — — 2SCRC-B05 — — — — — E0.005 — — — — — 1SCRC-B13 E0.006 — — — — — — — — — — 1SCRC-B14 E0.007 E0.005 — — — — — — — — — 2SCRC-B19 — — E0.005 — — — — — — — — 1SCRC-B21 E0.005 0.010 — 0.011 — — 0.008 — — — — 4SCRC-B22 E0.004 — E0.004 — — — — — — — — 2SCRC-B25 — — E0.005 — — — — — — — — 1SCRC-B27 E0.005 0.011 — — — — — — — — — 2SCRC-B28 E0.01 0.010 — — — — — — — — — 2

Table 6A. Pesticides and pesticide degradates detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.[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 69 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 54 grid wells sampled. All analytes are listed in table 3B. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. Environmental Protection Agency (USEPA) maximum contaminant level; HAL-US, USEPA lifetime health advisory level; MCL-CA, California Department of Public Health maximum contaminant level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; μg/L, micrograms per liter; na, not available; —, not detected]
56 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table 6A. Pesticides and pesticide degradates detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 69 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 54 grid wells sampled. All analytes are listed in table 3B. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. Environmental Protection Agency maximum contaminant level; HAL-US, U.S. Environmental Protection Agency lifetime health advisory 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; μg/L, microgram per liter; na, not available; —, not detected] Primary use or source Herbicide degradate Herbicide Fungicide Herbicide degradate Herbicide Insecticide degradate Herbicide Pesticide detections per well Any pesticide GAMA identification number Deethylatrazine (2-Chloro- 4-isopropylamino- 6-amino-s-triazine) (μg/L) (04040) Atrazine (μg/L) (39632) Simazine (μg/L) (04035) Metolachlor (μg/L) (39415) Metalaxyl (μg/L) (61596) 3,4-Dichlo- roaniline (μg/L) (61625) Acetochlor (μg/L) (49260) Fipronil sulfide (μg/L) (62167) Fipronil sulfone (μg/L) (62168) Prometon (μg/L) (04037) Dacthal (DCPA) (μg/L) (82682) Threshold type 1 na MCL-CA MCL-US HAL-US na na na na HAL-US HAL-US HAL-US Threshold level na 1 4 700 na na na na 100 100 70 [LRL] [0.014] [0.007] [0.01] [0.014] [0.0069] [0.004] [0.01] [0.013] [0.024] [0.02] [0.007] SCRC-B30 E0.006

—

—

—

—

—

—

—

—

—

— 1

SCRC-B32 E0.006

—

—

—

—

—

—

—

—

—

— 1

Number of 

wells with detections

9 5 3 2 0 1 1 0 0 0 0 13

Detection 

frequency (percent)

23.7 13.1 7.9 5.3 0 2.6 2.6 0 0 0 0 34

Total Detections 21

SCRC Uplands Study Area (16 grid wells sampled)

SCRC-H02

—

—

—

— E0.007

—

— E0.007 E0.007

—

— 3

SCRC-H11 E0.005

—

—

—

—

—

—

—

—

—

— 1

Number of 

wells with detections

1 0 0 0 1 0 0 1 1 0 0 2

Detection 

frequency (percent)

6.3 0 0 0 6.3 0 0 6.3 6.3 0 0 13

Total Detections 4
Tables 57

Table 6A. Pesticides and pesticide degradates detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 69 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 54 grid wells sampled. All analytes are listed in table 3B. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. Environmental Protection Agency maximum contaminant level; HAL-US, U.S. Environmental Protection Agency lifetime health advisory 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; μg/L, microgram per liter; na, not available; —, not detected]

Primary use 

or source

Herbicide 

degradate Herbicide Fungicide Herbicide degradate Herbicide Insecticide degradate Herbicide

Pesticide 

detections 

per well

Any 

pesticide GAMA 

identification 

number

Deethylatrazine 

(2-Chloro4-isopropylamino6-amino-s-triazine) 

(μg/L) (04040)

Atrazine 

(μg/L) 

(39632)

Simazine 

(μg/L) 

(04035)

Metolachlor 

(μg/L) 

(39415)

Metalaxyl 

(μg/L) 

(61596)

3,4-Dichloroaniline 

(μg/L) 

(61625)

Acetochlor 

(μg/L) 

(49260)

Fipronil 

sulfide 

(μg/L) 

(62167)

Fipronil 

sulfone 

(μg/L) 

(62168)

Prometon 

(μg/L) 

(04037)

Dacthal 

(DCPA) 

(μg/L) 

(82682)

Threshold type 1 na MCL-CA MCL-US HAL-US na na na na HAL-US HAL-US HAL-USThreshold level na 1 4 700 na na na na 100 100 70[LRL] [0.014] [0.007] [0.01] [0.014] [0.0069] [0.004] [0.01] [0.013] [0.024] [0.02] [0.007]

SCRC Understanding wells 3 (15 wells sampled)

SCRC-U04 — — 0.009 — — — — — — — — 1SCRC-U07 — — — — E0.008 — — — — — — 1SCRC-U08 — — E0.007 — — — — — — — — 1SCRC-U09 — — E0.005 — — — — — — — E0.003 2SCRC-U15 — — — — — — — — — E0.01 — 1

1 Maximum contaminant level thresholds 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 Sample from SCRC-B18 was ruined during sample preparation at the USGS National Water-Quality Laboratory.3 Understanding wells were not included in statistical calculations.
58 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table 6B. Polar pesticides and metabolites detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater 

Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.

[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 69 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the grid wells 

sampled. All analytes are listed in table 3C. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-U, understanding well. Laboratory 

reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: HAL-US, U.S. Environmental Protection Agency lifetime health 

advisory level. Other abbreviations: LRL, laboratory reporting level; μg/L, microgram per liter; na, not available; E, estimated or having a higher degree of 

uncertainty; —, not detected.]

Primary use or source Herbicide Metabolite Herbicide

Pesticide 

detections 

per well

Any 

pesticide

GAMA 

identification

number

Diuron 

(μg/L) 

(49300)

3-(4-Chlorophenyl)-1-

methyl urea 

(μg/L) 

(61692)

Bromacil 

(μg/L) 

(04029)

Fenuron 

(μg/L) 

(49297)

Threshold type HAL-US na HAL-US na

Threshold level 10 na 70 na

[LRL] [0.04] [0.06] [0.02] [0.06]

SCRC Grid wells (54 wells sampled) 1

SCRC-B05 E0.02 — — — 1

SCRC-B27 E0.01 — 0.08 — 2

SCRC-B28 — E0.01 — — 1

Number of wells with detections 2 1 1 0 3

Detection frequency (percent) 3.7 1.9 1.9 0 6

Total Detections 4

SCRC Understanding wells 2 (15 wells sampled)

SCRC-U12 — E0.02 — 0.14 2

1

 Sample from SCRC-B09 was ruined during sample preparation at the USGS National Water-Quality Laboratory.

2

 Understanding wells were not included in statistical calculations.
Tables 59

GAMA 

identification

number

Perchlorate 

(μg/L) 

(63790)

Threshold type 1 MCL-CA

Threshold level 6

[MRL] [0.10]

SCRC Grid wells (55 wells sampled)

Number of wells with detections 33

Detection frequency (percent) 60

SCRC Basins Study Area (39 grid wells sampled)

SCRC-B02 0.21

SCRC-B03 0.96

SCRC-B05 1.12

SCRC-B06 1.22

SCRC-B07 0.18

SCRC-B09 1.10

SCRC-B10 0.37

SCRC-B12 1.14

SCRC-B13 1.17

SCRC-B14 1.23

SCRC-B15 1.07

SCRC-B16 0.48

SCRC-B17 0.29

SCRC-B18 0.19

SCRC-B19 0.26

SCRC-B20 0.16

SCRC-B21 1.23

SCRC-B22 1.48

SCRC-B23 0.33

SCRC-B24 0.58

SCRC-B25 0.35

SCRC-B27 0.25

SCRC-B28 0.60

GAMA 

identification

number

Perchlorate 

(μg/L) 

(63790)

Threshold type 1 MCL-CA

Threshold level 6

[MRL] [0.10]

SCRC-B32 1.81

SCRC-B33 1.09

SCRC-B36 0.35

SCRC-B38 1.15

SCRC-B39 0.17

Number of wells with detections 28

Detection frequency (percent) 72

SCRC Uplands Study Area (16 grid wells sampled)

SCRC-H05 2.02

SCRC-H06 0.73

SCRC-H08 0.18

SCRC-H12 0.20

SCRC-H13 1.73

Number of wells with detections 5

Detection frequency (percent) 31

SCRC Understanding wells 2 (15 wells sampled)

SCRC-U03 0.80

SCRC-U04 0.17

SCRC-U06 0.39

SCRC-U07 0.95

SCRC-U08 0.28

SCRC-U09 0.77

SCRC-U10 0.92

SCRC-U12 0.69

Table 7. Perchlorate detected in the samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring 

and Assessment (GAMA) study, California, May to December 2008.

[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 3E. Samples from all 70 wells were analyzed for perchlorate, but only samples with detections are listed. GAMA 

identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, understanding well. Minimum reporting level, 

threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-CA, California Department of Public Health maximum contaminant level. 

Other abbreviations: MRL, method reporting level; μg/L, micrograms per liter]

1

 Maximum contaminant level thresholds 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

 Understanding wells were not included in statistical calculations.
60 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table 8. Trace elements detected in the samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 the 39 slow wells and the 3 surface-water sites were analyzed. Information about the analytes given in table 3F. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: 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: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; SRL, study reporting limit; μg/L, micrograms per liter; na, not available; nc, not collected; —, not detected; ≤, less than or equal to; *, value above threshold level] GAMA identification number Aluminum (μg/L) (01106) Antimony (μg/L) (01095) Arsenic (μg/L) (01000) Barium (μg/L) (01005) Beryllium (μg/L) (01010) Boron (μg/L) (01020) Cadmium (μg/L) (01025) Chromium (μg/L) (01030) Cobalt (μg/L) (01035) Copper (μg/L) (01040) Iron (μg/L) (01046) Lead (μg/L) (01049) Threshold type 1 MCL-CA MCL-US MCL-US MCL-CA MCL-US NL-CA MCL-US MCL-CA na AL-US SMCL-CA AL-US Threshold level 1,000 6 10 1,000 4 1,000 5 50 na 1,300 300 15 [LRL/SRL] 2 [1.6] [0.04] [0.06] 2 [0.36] [0.02] [4] [0.02] 2 [0.42] [0.02] 2 [1.7] 2 [6] 2 [0.65] SCRC Grid wells (32 wells sampled) SCRC-B05

— 0.16 1.0 17

— 125 E0.03 1.0 0.07 ≤0.76 9 ≤0.52

SCRC-B08 ≤0.9 E0.09 2.3 42

— 256 0.18 ≤0.34 0.33

— 48

—

SCRC-B10

—

— 5.3 24

— 86.0 0.99 ≤0.07 0.04 ≤0.97 13 ≤0.13

SCRC-B11 ≤1.0

— *17.5 32

— 446 0.05 ≤0.08 0.08

— *1,600 ≤0.34

SCRC-B16

— E0.12 0.50 16

— 200 0.12 0.76 0.18 ≤1.2 9 ≤0.34

SCRC-B21

— 0.28 1.4 44

— 357 0.09 ≤0.19 0.12

— *3,170

—

SCRC-B22 ≤1.1 E0.10 0.74 17

— 260 0.17 1.6 0.41 ≤1.3

— ≤0.25

SCRC-B23

—

— 1.9 25

— 122 0.32 1.0 0.05 3.8

— ≤0.51

SCRC-B26

—

— 3.2 96 E0.01 383 0.04

— 0.07

— *4,450

—

SCRC-B27

—

— 0.69 20

— 155 0.53 3.1 0.03 ≤0.75 E8 ≤0.18

SCRC-B28

— E0.11 0.81 72 E0.005 28.0 0.31 0.58 0.04 ≤0.54 E7 1.11

SCRC-B30

— E0.11 0.55 16

— 143 0.10 1.1 0.04 2.3

— 0.93

SCRC-B34

—

— 0.19 61

— 392

— ≤0.1 0.04

— 130

—

SCRC-B36

— E0.09 0.63 19

— 96.0 0.09 0.57 0.05 ≤0.56 E7 ≤0.26

SCRC-B37

—

— 8.7 66

— 307 E0.03

— 0.24

— 156

—

SCRC-B39

— 0.12 1.5 16

— 130 0.03 1.3 0.05 ≤0.98

— ≤0.64

SCRC-H01 1.8

— 0.08 13

— 215

— ≤0.07 E0.01

— 105

—

SCRC-H02

— E0.09 2.3 42

— 119 0.32 1.6 0.06 3.6 19 1.33

SCRC-H03 ≤0.8 0.17 *18.2 71

— 336 0.05 ≤0.14 0.11

— *430

—

SCRC-H04

—

— 2.4 46

— 598 0.38 ≤0.19 0.06

— 45 ≤0.09

SCRC-H05

—

— 2.4 39

— 77.0 0.11 12.8 E0.02 ≤1.2

— ≤0.16

SCRC-H06

—

— 5.3 6 — 98.0

— 0.53 0.02

— 11 ≤0.18

SCRC-H07

—

— 4.5 31

— 111 0.19

— 0.04

— 244 ≤0.07

SCRC-H08

—

— 6.7 79

— 378 0.46 1.3 E0.02 ≤0.87 11 ≤0.14

SCRC-H09

—

— 6.8 18 E0.005 64.0 0.15

— 0.04

— *577

—

Table 8. Trace elements detected in the samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.[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 the 39 slow wells and the 3 surface-water sites were analyzed. Information about the analytes given in table 3F. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: 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: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; SRL, study reporting limit; μg/L, micrograms per liter; na, not available; nc, not collected; —, not detected; ≤, less than or equal to; *, value above threshold level]
Tables 61

Table 8. Trace elements detected in the samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 the 39 slow wells and the 3 surface-water sites were analyzed. Information about the analytes given in table 3F. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: 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: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; SRL, study reporting limit; μg/L, micrograms per liter; na, not available; nc, not collected; —, not detected; ≤, less than or equal to; *, value above threshold level]

GAMA 

 identification 

number

Aluminum 

(μg/L) 

(01106) 

Antimony 

(μg/L) 

(01095) 

Arsenic 

(μg/L) 

(01000) 

Barium 

(μg/L) 

(01005) 

Beryllium 

(μg/L) 

(01010)

Boron 

(μg/L) 

(01020) 

Cadmium 

(μg/L) 

(01025) 

Chromium 

(μg/L) 

(01030) 

Cobalt 

(μg/L) 

(01035) 

Copper 

(μg/L) 

(01040) 

Iron 

(μg/L) 

(01046) 

Lead 

(μg/L) 

(01049) 

Threshold type 1 MCL-CA MCL-US MCL-US MCL-CA MCL-US NL-CA MCL-US MCL-CA na AL-US SMCL-CA AL-USThreshold level 1,000 6 10 1,000 4 1,000 5 50 na 1,300 300 15[LRL/SRL] 2 [1.6] [0.04] [0.06] 2 [0.36] [0.02] [4] [0.02] 2 [0.42] [0.02] 2 [1.7] 2 [6] 2 [0.65]SCRC-H10 ≤1.0 — 3.1 29 — 108 0.16 ≤0.13 0.06 ≤1.4 — ≤0.26SCRC-H11 — — 5.6 109 — 31.0 0.27 ≤0.23 0.06 2.4 — ≤0.36SCRC-H12 — — 5.9 31 — 147 0.58 — 0.06 ≤0.98 15 ≤0.64SCRC-H13 — 0.19 *14.2 13 — 41.0 0.64 ≤0.21 0.03 — 71 ≤0.05SCRC-H14 ≤1.4 — 0.40 427 — 402 — ≤0.19 0.15 — 29 —SCRC-H15 ≤1.5 — 0.65 33 — 37.0 2.6 ≤0.12 0.07 — 54 ≤0.08SCRC-H16 32.2 0.10 0.34 35 — 13.0 — ≤0.09 0.11 ≤1.1 7 ≤0.58

SCRC Surface-water sites (3 sites sampled)

SCRC-SW1 nc nc nc nc nc nc nc nc nc nc ≤4 ncSCRC-SW2 nc nc nc nc nc nc nc nc nc nc 12 ncSCRC-SW3 nc nc nc nc nc nc nc nc nc nc — nc

SCRC Understanding wells (7 wells sampled)

SCRC-U03 — 0.19 5.4 65 E0.01 250 0.63 0.43 0.18 ≤0.98 — ≤0.33SCRC-U06 — E0.07 1.0 43 — 106 0.18 1.5 0.03 ≤1.0 — ≤0.12SCRC-U07 — E0.08 0.75 43 — 135 0.28 1.3 0.15 ≤1.2 — ≤0.29SCRC-U08 — E0.11 0.89 14 — 88.0 0.08 ≤0.41 0.05 2.0 — 0.87SCRC-U09 7.2 E0.08 0.63 33 — 161 0.14 1.5 0.19 2.0 — 0.77SCRC-U10 2.8 E0.07 0.55 38 — 150 0.19 1.6 0.22 2.2 — ≤0.28SCRC-U15 ≤0.9 — 0.72 22 — 27.0 E0.03 1.4 0.23 ≤1.1 — —
62 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table 8. Trace elements detected in the samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 the 39 slow wells and the 3 surface- water sites were analyzed. Information about the analytes given in table 3F. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface- water site; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: 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: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; SRL, study reporting limit; μg/L, micrograms per liter; na, not available; nc, not collected; —, not detected; ≤, less than or equal to; *, value above threshold level] GAMA identification number Lithium (μg/L) (01130) Manganese (μg/L) (01056) Mercury (μg/L) (71890) Molyb- denum (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) Threshold type 1 na SMCL-CA MCL-US HAL-US MCL-CA MCL-US SMCL-CA HAL-US MCL-US na MCL-US NL-CA SMCL-CA Threshold level na 50 2 40 100 50 100 4,000 2 na 30 50 5,000 [LRL/SRL] [1] 2 [0.2] 2 [0.012] [0.02] 2 [0.36] [0.06] [0.008] [0.8] [0.04] 2 [0.11] [0.006] 2 [0.11] 2 [4.8] SCRC Grid wells (32 wells sampled) SCRC-B05 20.4 0.4 ≤0.007 5.9 0.69 2.4

— 613

—

— 3.35 2.8 45.3

SCRC-B08 21.9 *156 0.017 15.8 0.82 0.90

— 749

—

— 8.91 5.5 ≤0.91

SCRC-B10 31.8 27.8

— 12.7 2.2 3.4

— 223

—

— 0.05 5.8 ≤1.9

SCRC-B11 20.3 *948

— 25.3 1.6 0.18

— 1,070

—

— 3.35 0.20 5.6

SCRC-B16 23.4

— ≤0.007 5.9 2.7 1.9

— 1,340

—

— 5.15 1.5 ≤4.4

SCRC-B21 28.0 *1,030 ≤0.007 31.6 1.7 0.12

— 1,020

—

— 0.66 0.43

—

SCRC-B22 25.2 ≤0.1 ≤0.01 6.3 3.6 1.4

— 1,620

— ≤0.04 10.7 4.3 ≤4.0

SCRC-B23 9.9 0.2

— 9.8 0.59 2.3

— 519

— ≤0.04 4.73 10.0 ≤1.9

SCRC-B26 47.2 *559

— 15.4 1.2 0.11

— 946

— ≤0.03 0.25 0.24 ≤3.5

SCRC-B27 13.8 0.7

— 4.9 0.58 2.3

— 717

—

— 4.58 3.1 ≤4.3

SCRC-B28 E0.80 0.7

— 2.8 0.60 1.7

— 285

—

— 0.41 1.6 360

SCRC-B30 19.3

—

— 9.1 0.56 3.4

— 885

—

— 5.35 1.6 24.0

SCRC-B34 83.9 *254 ≤0.009 0.8 0.67 0.06

— 371

—

—

— 0.27 ≤1.4

SCRC-B36 10.3 0.3 ≤0.011 10.6 0.54 3.2

— 790

—

— 4.6 1.8 ≤4.8

SCRC-B37 35.3 *422

— 22.1 1.4 E0.02

— 566 E0.04

— 1.04 0.23 ≤1.2

SCRC-B39 18.3

— nc 4.2 0.55 3.3

— 604

— ≤0.06 4.33 4.3 ≤2.5

SCRC-H01 31.6 *142 ≤0.01 2.7 ≤0.30 0.05

— 148

— ≤0.05

— 0.14

—

SCRC-H02 19.7 7.1 0.017 25.9 3.1 2.3

— 545

—

— 6.02 5.3 18.9

SCRC-H03 20.4 24.1 ≤0.011 25.1 3.1 0.91

— 207

— 0.18 0.20 5.0 ≤2.9

SCRC-H04 152 *51.9

— *192 0.42 3.2

— 674 0.10

— 6.63 0.51 17.9

SCRC-H05 9.3 0.7

— 25.0 ≤0.32 3.1

— 255

—

— 3.95 18.5 ≤1.7

SCRC-H06 16.3 13.5 ≤0.005 4.1 0.77 1.7

— 125

—

—

— 2.2 ≤2.2

SCRC-H07 23.1 *51.8 ≤0.009 *78.9 0.57 8.8

— 217

—

— 0.2 0.45 25.2

SCRC-H08 87.7 17.3 0.015 *218 ≤0.19 0.94

— 542

— ≤0.06 4.83 6.5 ≤3.1

SCRC-H09 11.5 29.8 ≤0.006 *72.4 0.46 E0.03

— 382

—

— 8.29 ≤0.06

—
Tables 63

Table 8. Trace elements detected in the samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 the 39 slow wells and the 3 surfacewater sites were analyzed. Information about the analytes given in table 3F. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surfacewater site; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: 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: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; SRL, study reporting limit; μg/L, micrograms per liter; na, not available; nc, not collected; —, not detected; ≤, less than or equal to; *, value above threshold level]

GAMA 

identification 

number

Lithium 

(μg/L) 

(01130) 

Manganese 

(μg/L) 

(01056) 

Mercury 

(μg/L) 

(71890) 

Molybdenum 

(μg/L) 

(01060) 

Nickel 

(μg/L) 

(01065) 

Selenium 

(μg/L) 

(01145) 

Silver 

(μg/L) 

(01075) 

Strontium 

(μg/L) 

(01080)

Thallium 

(μg/L) 

(01057) 

Tungsten 

(μg/L) 

(01155)

Uranium 

(μg/L) 

(22703)

Vanadium 

(μg/L) 

(01085) 

Zinc 

(μg/L) 

(01090)

Threshold type 1 na SMCL-CA MCL-US HAL-US MCL-CA MCL-US SMCL-CA HAL-US MCL-US na MCL-US NL-CA SMCL-CAThreshold level na 50 2 40 100 50 100 4,000 2 na 30 50 5,000[LRL/SRL] [1] 2 [0.2] 2 [0.012] [0.02] 2 [0.36] [0.06] [0.008] [0.8] [0.04] 2 [0.11] [0.006] 2 [0.11] 2 [4.8]SCRC-H10 25.3 11.9 — 38.0 0.96 6.5 — 724 — — 8.82 11.3 6.5SCRC-H11 11.2 0.8 0.014 *80.9 1.0 2.8 — 337 — — 16.2 6.0 13.4SCRC-H12 30.2 11.1 — *46.1 0.72 0.83 — 460 — — 0.66 1.8 ≤3.2SCRC-H13 7.3 9.7 — *323 0.96 28.9 — 102 — — 2.29 1.7 ≤2.2SCRC-H14 15.3 24.7 — 0.6 1.2 0.13 — 403 — ≤0.08 0.42 0.48 ≤1.9SCRC-H15 11.3 28.5 — *40.7 0.99 1.2 — 552 — — 8.07 4.2 ≤3.9SCRC-H16 — 11.1 nc 0.2 0.97 E0.06 E0.004 20.6 — — 0.01 0.32 5.0

SCRC Surface-water sites (3 sites sampled)

SCRC-SW1 nc 1.7 nc nc nc nc nc nc nc nc nc nc ncSCRC-SW2 nc 31.6 nc nc nc nc nc nc nc nc nc nc ncSCRC-SW3 nc 20.1 nc nc nc nc nc nc nc nc nc nc nc

SCRC Understanding wells (7 wells sampled)

SCRC-U03 54.4 *136 ≤0.009 *71.7 1.7 18.8 — 660 — — 23.1 8.4 ≤2.0SCRC-U06 11.4 ≤0.2 — 5.0 0.37 2.1 — 668 — — 3.08 3.2 —SCRC-U07 22.6 — — 4.5 1.5 3.6 — 1,490 — — 9.22 1.9 ≤4.0SCRC-U08 10.8 0.4 — 10.6 0.52 3.2 — 540 — — 3.25 1.9 12.1SCRC-U09 21.2 ≤0.1 — 5.5 2.3 3.2 — 1,130 — — 6.88 1.9 8.0SCRC-U10 20.2 ≤0.2 — 3.5 3.1 2.7 — 1,110 — — 5.94 1.6 5.6SCRC-U15 4.1 7.7 — 0.4 1.3 0.07 — 76.0 — — E0.01 1.1 ≤1.0

1 Maximum contaminant level thresholds 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 Study reporting limits (SRL) were defined on the basis of the examination of GAMA quality-control (QA) samples collected from May 2004 through January 2008 (Olsen and others, 2010). Values 

below the SRL are reported as less than or equal to the value reported by the laboratory (≤). In the USGS National Water Information System (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, National Water Quality Laboratory (NWQL) set blanks, NWQL blank water certificates, and USGS Office of Water Quality Branch of Quality Systems Blind Blank Program data).
64 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table 9. Nutrients and dissolved organic carbon (DOC) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 42 wells and the 3 surface-water sites were analyzed. Information about the analytes given in table 3G. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; mg/L, milligrams per liter; na, not available; nc, not collected; —, not detected; *, value above threshold level] GAMA identification number Ammonia, as nitrogen (mg/L) (00608) Ammonia, plus organic nitrogen (unfiltered) (mg/L) (00625) Ammonia, plus organic nitrogen (filtered) (mg/L) (00623) 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) Phosphorus, as phosphorus (filtered) (mg/L) (00666) Phosphate, orthophosphate (as phosphorus) (mg/L) (00671) Phosphorus, as phosphorus (unfiltered) (mg/L) (00665) Dissolved organic carbon (DOC) (mg/L) (00681) Threshold type 1 HAL-US na na MCL-US MCL-US na na na na na Threshold level 2 24.7 na na 1 10 na na na na na [LRL] [0.02] [0.1] [0.1] [0.002] [0.04] [0.06] [0.04] [0.006] [0.040] [0.4] SCRC Grid wells (33 wells sampled) SCRC-B05

— nc nc

— 8.38 8.64 nc 0.025 nc V0.5

SCRC-B08

— nc nc E0.001 0.50 0.56 nc 0.068 nc 1.0

SCRC-B10

— nc nc

— 1.75 1.82 nc 0.800 nc 1.4

SCRC-B11 0.51 nc nc E0.002 E0.02 0.63 nc 0.296 nc 2.5SCRC-B16

— nc nc 0.002 *35.6 37.4 nc 0.019 nc 1.0

SCRC-B21 1.54 nc nc

—

— 1.58 nc 0.177 nc 2.9

SCRC-B22

— nc nc

— *25.9 26.1 nc 0.023 nc 0.8

SCRC-B23

— nc nc

— 2.81 3 2.76 nc 0.042 nc V0.2

SCRC-B26 2.09 nc nc E0.001

— 2.42 nc 0.391 nc 3.9

SCRC-B27

— nc nc

— 1.67 1.68 nc 0.050 nc

—

SCRC-B28 0.03 nc nc 0.013 7.86 8.06 nc 0.177 nc 1.3SCRC-B29 0.09 nc nc

—

— 0.12 nc 0.028 nc nc

SCRC-B30

— nc nc

— *12.0 12.5 nc 0.025 nc V0.5

SCRC-B34 1.80 nc nc 0.004 E0.03 1.97 nc 0.124 nc 1.3SCRC-B36

— nc nc

— 6.75 6.80 nc 0.025 nc V0.5

SCRC-B37 1.62 nc nc

—

— 1.74 nc 0.104 nc 1.4

SCRC-B39

— nc nc

— 0.46 4 0.41 nc 0.015 nc nc

Table 9. Nutrients and dissolved organic carbon (DOC) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.[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 42 wells and the 3 surface-water sites were analyzed. Information about the analytes given in table 3G. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: HAL-US, U.S. Environmental Protection Agency (USEPA)lifetime health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; mg/L, milligrams per liter; na, not available; nc, not collected; —, not detected; *, value above threshold level]
Tables 65

Table 9. Nutrients and dissolved organic carbon (DOC) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 42 wells and the 3 surface-water sites were analyzed. Information about the analytes given in table 3G. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; mg/L, milligrams per liter; na, not available; nc, not collected; —, not detected; *, value above threshold level]

GAMA 

identification 

number

Ammonia, 

as nitrogen 

(mg/L) 

(00608)

Ammonia, 

plus organic 

nitrogen 

(unfiltered)

 (mg/L) 

(00625)

Ammonia, 

plus organic 

nitrogen 

(filtered) 

(mg/L) 

(00623)

 Nitrite, as 

nitrogen 

(mg/L) 

(00613)

Nitrite plus 

nitrate, 

as nitrogen 

(mg/L) 

(00631)

Total nitrogen 

(ammonia + nitrate 

+ nitrite + organicnitrogen) 

as nitrogen 

(mg/L) 

(62854)

Phosphorus, as 

phosphorus 

(filtered) 

(mg/L) 

(00666)

Phosphate, 

orthophosphate 

(as phosphorus) 

(mg/L) 

(00671)

Phosphorus, 

as phosphorus 

(unfiltered) 

(mg/L) 

(00665)

Dissolved 

organic 

carbon 

(DOC) 

(mg/L) 

(00681)

Threshold type 1 HAL-US na na MCL-US MCL-US na na na na naThreshold level 2 24.7 na na 1 10 na na na na na[LRL] [0.02] [0.1] [0.1] [0.002] [0.04] [0.06] [0.04] [0.006] [0.040] [0.4]SCRC-H01 0.30 nc nc — — 0.35 nc 0.048 nc 1.3SCRC-H02 — nc nc — 0.06 0.13 nc 0.193 nc 2.3SCRC-H03 0.09 nc nc 0.005 0.58 0.77 nc 0.921 nc 1.0SCRC-H04 0.17 nc nc — 0.06 0.25 nc 0.032 nc V0.4SCRC-H05 — nc nc — 2.70 2.66 nc 0.023 nc V0.4SCRC-H06 0.14 nc nc E0.001 2.65 2.83 nc 0.877 nc 0.7SCRC-H07 0.05 nc nc — E0.03 4 0.07 nc 0.199 nc V0.5SCRC-H08 E0.0 nc nc 0.003 0.37 0.40 nc 0.025 nc V0.3SCRC-H09 0.03 nc nc — — — nc 0.021 nc 0.7SCRC-H10 — nc nc — 1.85 3 1.80 nc 0.021 nc V0.5SCRC-H11 — nc nc — 0.14 0.14 nc 0.028 nc V0.3SCRC-H12 0.12 nc nc E0.001 0.32 0.46 nc 0.029 nc 0.8SCRC-H13 — nc nc E0.002 2.28 2.45 nc 0.083 nc V0.3SCRC-H14 0.14 nc nc 0.025 0.14 0.38 nc 0.046 nc 0.9SCRC-H15 — nc nc — 0.36 0.37 nc 0.035 nc V0.4SCRC-H16 0.09 nc nc 0.004 0.10 4 0.15 nc 0.029 nc nc
66 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table 9. Nutrients and dissolved organic carbon (DOC) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 42 wells and the 3 surface-water sites were analyzed. Information about the analytes given in table 3G. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; mg/L, milligrams per liter; na, not available; nc, not collected; —, not detected; *, value above threshold level] GAMA identification number Ammonia, as nitrogen (mg/L) (00608) Ammonia, plus organic nitrogen (unfiltered) (mg/L) (00625) Ammonia, plus organic nitrogen (filtered) (mg/L) (00623) 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) Phosphorus, as phosphorus (filtered) (mg/L) (00666) Phosphate, orthophosphate (as phosphorus) (mg/L) (00671) Phosphorus, as phosphorus (unfiltered) (mg/L) (00665) Dissolved organic carbon (DOC) (mg/L) (00681) Threshold type 1 HAL-US na na MCL-US MCL-US na na na na na Threshold level 2 24.7 na na 1 10 na na na na na [LRL] [0.02] [0.1] [0.1] [0.002] [0.04] [0.06] [0.04] [0.006] [0.040] [0.4] SCRC Surface-water sites (3 sites sampled) SCRC-SW1 E0.01 0.4 0.3 0.061 *70.0 nc 0.12 0.130 0.240 nc SCRC-SW2 0.83 2.2 1.8 0.310 *37.4 nc 0.15 0.135 0.720 nc SCRC-SW3 0.05 0.5 0.5 0.215 *25.2 nc 0.08 0.079 0.110 nc SCRC Understanding wells (9 wells sampled) SCRC-U03

— nc nc 0.008 5.73 3 5.61 nc 0.098 nc 1.7

SCRC-U04

— nc nc

— 5.08 5.18 nc 0.118 nc nc

SCRC-U05

— nc nc

— 2.19 2.27 nc 0.231 nc nc

SCRC-U06

— nc nc

— 2.23 2.37 nc 0.069 nc V0.2

SCRC-U07

— nc nc

— *77.3 81.8 nc 0.053 nc 1.3

SCRC-U08

— nc nc

— 3.17 3.33 nc 0.047 nc 0.9

SCRC-U09

— nc nc

— *67.8 3 67.2 nc 0.062 nc 1.1

SCRC-U10

— nc nc

— *73.3 77.5 nc 0.068 nc 1.1

SCRC-U15

— nc nc 0.005 1.99 2.17 nc 0.303 nc 1.4

1 Maximum contaminant level thresholds 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 HAL-US is 30 mg/L “as ammonia.” To facilitate comparson to the analytical results, we have converted and reported this HAL-US as 24.7 mg/L “as nitrogen.”3 Total nitrogen in these samples is less than the sum of the filtered nitrogen analytes, but falls within the U.S. Geological Survey National Water Quality Laboratory acceptance criterion of a 10 percent or 

less relative percent difference. 

4 Total nitrogen in these samples is less than the sum of the filtered nitrogen analytes and falls outside the U.S. Geological Survey National Water-Quality Laboratory acceptance criterion of a 10 percent 

relative percent difference. However, the absolute difference is ≤0.05 mg/L.
Tables 67

Table 10. Major and minor ions, silica, and total dissolved solids (TDS) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 the 39 slow wells and the 3 surfacewater sites were analyzed. Information about the analytes given in table 3H. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surfacewater site; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: LRL, laboratory reporting level; mg/L, milligrams per liter; na, not available; SiO2, silicon dioxide; E, estimated or having a higher degree of uncertainty; nc, not collected; —, not detected; *, value above threshold level; **, value above upper threshold level]

GAMA 

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) 

Residue on 

evaporation 

(Total dissolved 

solids [TDS]) 

(mg/L) 

(70300)

Threshold type 1 na na SMCL-CA MCL-CA na na na na na SMCL-CA SMCL-CAThreshold level na na 2 250 (500) 2 na na na na na 2 250 (500) 2 500 (1,000)[LRL] [0.02] [0.04] [0.12] [0.08] [0.002] [0.012] [0.06] [0.02] [0.12] [0.18] [10]

SCRC Grid wells (32 wells sampled)

SCRC-B05 0.28 108 70.9 0.37 E0.002 59.6 2.57 30.3 53.6 *300 *838SCRC-B08 0.22 109 57.0 0.33 0.021 53.4 2.62 33.6 59.7 *251 *828SCRC-B10 0.27 50.2 69.4 0.15 0.006 20.9 3.08 55.3 46.7 128 456SCRC-B11 0.27 140 88.7 0.29 0.015 70.2 2.84 38.2 82.5 *383 **1,090SCRC-B16 0.65 170 60.4 0.46 0.003 89.6 3.95 23.6 82.9 **514 **1,320SCRC-B21 1.08 221 *274 0.14 0.050 128 6.54 38.5 186 **673 **1,920SCRC-B22 0.96 197 189 0.43 0.004 87.3 4.84 27.7 152 **514 **1,570SCRC-B23 0.14 91.5 40.2 0.24 — 40.2 2.79 42.7 56.0 *288 *725SCRC-B26 1.15 176.0 359 0.20 0.072 88.2 9.26 37.0 222 *373 **1,680SCRC-B27 0.13 104 39.7 0.32 — 37.4 3.24 38.4 60.4 *311 *752SCRC-B28 0.16 22.4 53.3 E0.08 0.013 7.70 2.07 41.5 45.6 38.0 272SCRC-B30 0.26 127 34.4 0.50 E0.001 50.1 3.29 27.2 62.0 *314 *837SCRC-B34 0.59 109 166 0.15 0.063 25.4 6.75 48.4 108 136 *807SCRC-B36 0.17 113 33.6 0.46 E0.001 43.7 2.87 28.8 56.5 *309 *850SCRC-B37 0.68 136 238 0.21 0.051 31.0 6.15 41.7 139 142 *980SCRC-B39 0.07 106 26.0 0.20 — 47.7 3.18 38.8 59.3 *312 *768SCRC-H01 0.27 41.0 85.5 0.14 0.056 17.7 4.06 62.8 68.6 44.0 450SCRC-H02 0.02 88.1 18.0 0.76 0.004 75.9 1.61 28.5 36.8 *264 *767SCRC-H03 0.11 43.5 25.6 0.84 0.034 11.2 3.56 50.1 56.5 72.0 384SCRC-H04 0.43 59.8 141 0.27 0.056 25.7 4.07 40.8 172 93.1 *778SCRC-H05 0.17 32.2 46.0 0.22 0.002 42.9 1.96 44.0 33.5 13.3 388SCRC-H06 0.41 34.0 120 0.48 0.046 9.24 2.67 53.8 76.2 24.2 405SCRC-H07 0.38 70.4 106 0.41 0.038 14.5 3.02 42.0 73.3 78.5 *518SCRC-H08 0.19 30.5 49.3 0.19 0.075 26.2 4.09 48.0 150 66.0 *606

Table 10. Major and minor ions, silica, and total dissolved solids (TDS) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.[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 the 39 slow wells and the 3 surface-water sites were analyzed. Information about the analytes given in table 3H. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: LRL, laboratory reporting level; mg/L, milligrams per liter; na, not available; SiO2, silicon dioxide; E, estimated or having a higher degree of uncertainty; nc, not collected; —, not detected; *, value above threshold level; **, value above upper threshold level]
68 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table 10. Major and minor ions, silica, and total dissolved solids (TDS) detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 the 39 slow wells and the 3 surface- water sites were analyzed. Information about the analytes given in table 3H. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-SW, surface- water site; SCRC-U, understanding well. Laboratory reporting level, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: LRL, laboratory reporting level; mg/L, milligrams per liter; na, not available; SiO2, silicon dioxide; E, estimated or having a higher degree of uncertainty; nc, not collected; —, not detected; *, value above threshold level; **, value above upper threshold level] GAMA 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) Residue on evaporation (Total dissolved solids [TDS]) (mg/L) (70300) Threshold type 1 na na SMCL-CA MCL-CA na na na na na SMCL-CA SMCL-CA Threshold level na na 2 250 (500) 2 na na na na na 2 250 (500) 2 500 (1,000) [LRL] [0.02] [0.04] [0.12] [0.08] [0.002] [0.012] [0.06] [0.02] [0.12] [0.18] [10] SCRC-H09 0.13 79.3 39.0 0.48 0.004 35.0 2.05 27.9 33.9 166 *536 SCRC-H10 0.19 116 45.6 0.20 0.013 58.1 3.30 50.8 47.2 234 *794 SCRC-H11 0.27 94.7 89.7 0.49 0.020 29.9 1.43 37.5 40.0 29.6 *502 SCRC-H12 0.22 95.2 55.1 0.41 0.024 38.7 3.12 37.2 74.7 *261 *756 SCRC-H13 0.22 36.5 66.6 0.39 0.018 4.89 1.34 48.1 43.1 23.0 305 SCRC-H14 0.32 70.8 94.7 0.46 0.065 34.2 7.66 52.5 98.8 51.3 *633 SCRC-H15 0.06 97.4 16.1 0.33 0.022 45.9 2.91 47.9 33.5 218 *675 SCRC-H16 0.11 58.8 36.5 0.14 0.019 32.0 5.34 48.8 97.9 65.2 *567 SCRC Surface-water sites (3 sites sampled) SCRC-SW1 nc 185 80.9 0.23 nc 61.3 3.81 26.9 76.8 *359 **1,420 SCRC-SW2 nc 174 68.3 0.38 nc 66.5 4.72 22.3 79.1 *471 **1,300 SCRC-SW3 nc 183 80.7 0.34 nc 60.8 5.66 22.7 100 **579 **1,270 SCRC Understanding wells (7 wells sampled) SCRC-U03 0.79 127 204 0.22 0.033 49.2 5.38 38.4 135 240 **1,040 SCRC-U06 0.11 85.4 37.1 0.35

— 30.3 2.69 32.5 52.9 *277 *668

SCRC-U07 0.62 242 82.6 0.30 0.004 84.6 3.72 24.5 81.5 *474 **1,600SCRC-U08 0.10 76.7 26.9 0.49 0.002 29.0 2.46 21.2 42.5 186 *540SCRC-U09 0.59 207 76.6 0.31 0.004 69.5 3.37 29.6 76.1 *381 **1,340SCRC-U10 0.65 205 84.0 0.20 0.004 69.8 3.21 31.3 81.2 *364 **1,340SCRC-U15 0.17 9.78 47.4 0.22 0.015 6.98 2.84 26.2 30.8 22.1 177

1 Maximum contaminant level thresholds 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 SMCL-CA for chloride, sulfate, and TDS have recommended and upper threshold values. The upper value is shown in parentheses.
Tables 69

Table 11. Species of inorganic arsenic and iron detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater 

Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.

[Data in this table analyzed at the U.S. Geological Survey (USGS) Trace Metals Laboratory using research methods and are not stored in the USGS National 

Water Information System database. Information about the analytes given in table 3I. Samples from the 39 slow wells were analyzed, but only samples with 

at least one detection are listed. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, 

understanding well. Method detection limit, threshold type, and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. Environmental 

Protection Agency maximum contaminant level; SMCL-CA, California Department of Public Health secondary maximum contaminant level. Other 

abbreviations: MDL, method detection limit; na, not available; μg/L, micrograms per liter; —, not detected; *, value above threshold level]

GAMA 

identification 

number

Arsenic 

(μg/L) 

Arsenic (III) 

(μg/L) 

Iron 

(μg/L) 

Iron (II) 

(μg/L) 

Threshold type 1 MCL-US na SMCL-CA na

Threshold level 10 na 300 na

[MDL] [0.5] [1] [2] [2]

SCRC Grid wells (32 wells sampled)

SCRC-B05 0.6 — 6 3

SCRC-B08 1.4 — 40 30

SCRC-B10 4.5 — 9 8

SCRC-B11 *15 12 *1,440 1,320

SCRC-B16 — — 6 3

SCRC-B21 0.7 — *2,960 2,890

SCRC-B23 0.8 — 3 —

SCRC-B26 2.1 2.0 *4,080 4,060

SCRC-B27 — — 8 —

SCRC-B34 — — 110 108

SCRC-B36 — — 6 4

SCRC-B37 7.3 6.6 137 133

SCRC-B39 na 2 na 2 na 2 na 2

SCRC-H01 — — 86 86

SCRC-H02 0.8 — 15 7

SCRC-H03 *13 2.3 *352 351

SCRC-H04 1.9 — 38 25

SCRC-H05 1.1 — 4 —

GAMA 

identification 

number

Arsenic 

(μg/L) 

Arsenic (III) 

(μg/L) 

Iron 

(μg/L) 

Iron (II) 

(μg/L) 

Threshold type 1 MCL-US na SMCL-CA na

Threshold level 10 na 300 na

[MDL] [0.5] [1] [2] [2]

SCRC Grid wells (32 wells sampled)—Continued

SCRC-H06 2.6 — 9 8

SCRC-H07 2.3 — 200 200

SCRC-H08 4.9 — 8 4

SCRC-H09 5.1 3.7 *490 477

SCRC-H10 1.3 — 4 —

SCRC-H11 4.3 — 3 3

SCRC-H12 4.7 — 15 6

SCRC-H13 *11 — 59 46

SCRC-H14 1.1 1.1 29 29

SCRC-H15 — — 43 36

SCRC-H16 na 2 na 2 na 2 na 2

SCRC Understanding wells (7 wells sampled)

SCRC-U03 3.9 — — —

SCRC-U06 0.6 — 4 —

SCRC-U08 0.6 — — —

SCRC-U09 — — 3 —

SCRC-U15 — — 2 2

1

 Maximum contaminant level thresholds 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

 Analyses at the USGS Trace Metals Laboratory were not completed in time for inclusion in this report; complete results will be presented in a subsequent 

publication.
70 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table 12. Results for analyses of stable isotope ratios, tritium activity, and carbon-14 abundance detected in samples collected 

for hern Coast RangeSCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—

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 table 3J. Samples from all 70 wells and the 3 surface-water sites were analyzed for stable isotopes of hydrogen and 

oxygen in water. Samples from all 70 wells were analyzed for tritium activities. Samples from the 12 special study wells and the 3 surface-water sites were 

analyzed for stable isotopes of nitrogen in dissolved nitrate. Samples from the 39 slow wells were analyzed for stable isotopes of carbon 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. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study 

area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Threshold type and threshold level as of November 17, 2008. Threshold type:

MCL-CA, California Department of Public Health maximum contaminant level. Other abbreviations: H, hydrogen; O, oxygen; N, nitrogen; C, carbon; pCi/L, 

picocuries per liter; na, not available; nc, not collected; —, not detected]

GAMA 

identification 

number

δ2H

(per mil)

(82082)

δ18O

(per mil) 

(82085)

Tritium

(pCi/L)

(07000)

δ15N

of nitrate

(per mil)

(82690)

δ18O

of nitrate

(per mil)

(63041)

δ13C

(per mil) 

(82081)

Carbon-14 

(percent 

modern) 

(49933)

Threshold type 1 na na MCL-CA na na na na

Threshold level na na 20,000 na na na na

SCRC Grid wells (55 wells sampled)

SCRC-B01 –35.9 –5.69 0.45 nc nc nc nc

SCRC-B02 –31.9 –5.21 6.5 nc nc nc nc

SCRC-B03 –44.9 –6.57 6.5 nc nc nc nc

SCRC-B04 –33.0 –5.30 0.77 nc nc nc nc

SCRC-B05 –45.1 –6.64 5.0 nc nc –10.14 79.15

SCRC-B06 –42.9 –6.55 1.2 nc nc nc nc

SCRC-B07 –39.6 –5.78 1.4 nc nc nc nc

SCRC-B08 –40.0 –5.89 — nc nc –13.07 71.27

SCRC-B09 –38.8 –5.82 0.73 nc nc nc nc

SCRC-B10 –38.1 –5.56 1.2 nc nc –16.05 76.77

SCRC-B11 –33.0 –4.90 5.5 nc nc –13.76 90.04

SCRC-B12 –39.0 –5.65 5.1 nc nc nc nc

SCRC-B13 –39.3 –5.85 2.0 nc nc nc nc

SCRC-B14 –45.2 –6.49 6.5 nc nc nc nc

SCRC-B15 –43.6 –6.29 9.1 nc nc nc nc

SCRC-B16 –42.5 –6.27 9.3 nc nc –11.23 102.6

SCRC-B17 –46.1 –6.84 7.8 nc nc nc nc

SCRC-B18 –40.7 –5.94 7.3 nc nc nc nc

SCRC-B19 –48.2 –6.88 5.5 nc nc nc nc

SCRC-B20 –46.6 –6.84 5.9 nc nc nc nc

SCRC-B21 –32.6 –5.14 1.9 nc nc –14.38 70.15

SCRC-B22 –44.5 –6.39 4.8 nc nc –12.56 93.97

SCRC-B23 –43.3 –6.50 0.64 3.77 3.13 –11.51 65.48

SCRC-B24 –46.6 –6.83 0.67 nc nc nc nc

SCRC-B25 –40.3 –6.10 7.0 nc nc nc nc

SCRC-B26 –31.7 –4.95 3.2 nc nc –15.56 80.73

SCRC-B27 –42.5 –6.59 — 3.27 2.36 –10.56 61.42

SCRC-B28 –36.9 –5.95 5.0 7.44 3.26 –15.60 76.45

SCRC-B29 –32.6 –5.00 2.4 nc nc nc nc

Table 12. Results for analyses of stable isotope ratios, tritium activity, and carbon-14 abundance detected in samples collected for the 

Southern Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 

2008.

[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 table 3J. Samples from all 70 wells and the 3 surface-water sites were analyzed for stable isotopes of hydrogen and 

oxygen in water. Samples from all 70 wells were analyzed for tritium activities. Samples from the 12 special study wells and the 3 surface-water sites were 

analyzed for stable isotopes of nitrogen in dissolved nitrate. Samples from the 39 slow wells were analyzed for stable isotopes of carbon 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. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study 

area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Threshold type and threshold level as of November 17, 2008. Threshold type:

MCL-CA, California Department of Public Health maximum contaminant level. Other abbreviations: H, hydrogen; O, oxygen; N, nitrogen; C, carbon; pCi/L, 

picocuries per liter; na, not available; nc, not collected; —, not detected]
Tables 71

Table 12. Results for analyses of stable isotope ratios, tritium activity, and carbon-14 abundance detected in samples collected 

for hern Coast RangeSCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—

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 table 3J. Samples from all 70 wells and the 3 surface-water sites were analyzed for stable isotopes of hydrogen and 

oxygen in water. Samples from all 70 wells were analyzed for tritium activities. Samples from the 12 special study wells and the 3 surface-water sites were 

analyzed for stable isotopes of nitrogen in dissolved nitrate. Samples from the 39 slow wells were analyzed for stable isotopes of carbon 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. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study 

area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Threshold type and threshold level as of November 17, 2008. Threshold type:

MCL-CA, California Department of Public Health maximum contaminant level. Other abbreviations: H, hydrogen; O, oxygen; N, nitrogen; C, carbon; pCi/L, 

picocuries per liter; na, not available; nc, not collected; —, not detected]

GAMA 

identification 

number

δ2H

(per mil)

(82082)

δ18O

(per mil) 

(82085)

Tritium

(pCi/L)

(07000)

δ15N

of nitrate

(per mil)

(82690)

δ18O

of nitrate

(per mil)

(63041)

δ13C

(per mil) 

(82081)

Carbon-14 

(percent 

modern) 

(49933)

Threshold type 1 na na MCL-CA na na na na

Threshold level na na 20,000 na na na na

SCRC-B30 –43.1 –6.46 7.2 3.88 4.57 –11.97 93.67

SCRC-B31 –45.8 –6.73 0.67 nc nc nc nc

SCRC-B32 –40.0 .91 3.6 nc nc nc nc

SCRC-B33 –36.8 –5.72 — nc nc nc nc

SCRC-B34 –36.1 –5.87 — nc nc –11.11 15.55

SCRC-B35 –34.1 –4.92 3.0 nc nc nc nc

SCRC-B36 –43.5 –6.50 6.4 3.68 4.00 –11.98 96.22

SCRC-B37 –33.5 –5.41 3.4 nc nc –12.85 61.37

SCRC-B38 –38.4 –6.17 — nc nc nc nc

SCRC-B39 –49.1 –7.13 — nc nc –9.50 54.32

SCRC-H01 –37.0 –5.91 — nc nc –14.71 10.91

SCRC-H02 –41.3 –6.64 5.8 nc nc –10.71 88.43

SCRC-H03 –39.6 –6.11 1.0 nc nc –11.18 17.02

SCRC-H04 –49.7 –7.26 — nc nc –9.76 1.64

SCRC-H05 –41.3 –6.00 0.35 nc nc –12.73 26.80

SCRC-H06 –36.9 –5.72 1.6 nc nc –13.72 56.05

SCRC-H07 –39.2 –5.74 1.0 nc nc –12.57 48.75

SCRC-H08 –49.1 –7.02 — nc nc –11.09 2.21

SCRC-H09 –39.5 –5.71 1.1 nc nc –11.03 62.42

SCRC-H10 –39.9 –5.88 — nc nc –11.27 14.93

SCRC-H11 –34.6 –5.17 1.1 nc nc –9.62 23.59

SCRC-H12 –42.0 –6.14 0.54 nc nc –12.29 40.89

SCRC-H13 –37.8 –5.74 — nc nc –12.26 59.52

SCRC-H14 –33.9 –5.26 — nc nc –12.91 24.32

SCRC-H15 –41.0 –6.03 — nc nc –11.01 33.82

SCRC-H16 –50.6 –7.37 0.73 nc nc –8.92 8.80

SCRC Surface-water sites (3 sites sampled

SCRC-SW1 –38.4 –5.25 nc 4.97 5.66 nc nc

SCRC-SW2 –37.2 –5.47 nc 7.09 7.50 nc nc

SCRC-SW3 –39.4 –5.91 nc 10.83 9.92 nc nc
72 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table 12. Results for analyses of stable isotope ratios, tritium activity, and carbon-14 abundance detected in samples collected 

for hern Coast RangeSCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—

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 table 3J. Samples from all 70 wells and the 3 surface-water sites were analyzed for stable isotopes of hydrogen and 

oxygen in water. Samples from all 70 wells were analyzed for tritium activities. Samples from the 12 special study wells and the 3 surface-water sites were 

analyzed for stable isotopes of nitrogen in dissolved nitrate. Samples from the 39 slow wells were analyzed for stable isotopes of carbon 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. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study 

area grid well; SCRC-SW, surface-water site; SCRC-U, understanding well. Threshold type and threshold level as of November 17, 2008. Threshold type:

MCL-CA, California Department of Public Health maximum contaminant level. Other abbreviations: H, hydrogen; O, oxygen; N, nitrogen; C, carbon; pCi/L, 

picocuries per liter; na, not available; nc, not collected; —, not detected]

GAMA 

identification 

number

δ2H

(per mil)

(82082)

δ18O

(per mil) 

(82085)

Tritium

(pCi/L)

(07000)

δ15N

of nitrate

(per mil)

(82690)

δ18O

of nitrate

(per mil)

(63041)

δ13C

(per mil) 

(82081)

Carbon-14 

(percent 

modern) 

(49933)

Threshold type 1 na na MCL-CA na na na na

Threshold level na na 20,000 na na na na

SCRC Understanding wells (15 wells sampled)

SCRC-U01 –35.7 –5.39 1.9 nc nc nc nc

SCRC-U02 –34.8 –5.23 4.2 nc nc nc nc

SCRC-U03 –33.8 –5.37 1.2 nc nc –13.40 78.57

SCRC-U04 –29.2 –4.51 5.2 14.61 14.79 nc nc

SCRC-U05 –38.3 –5.84 6.5 1.15 2.11 nc nc

SCRC-U06 –43.0 –6.52 — 3.29 2.71 –11.04 72.04

SCRC-U07 –38.5 –5.82 5.3 5.06 5.87 –14.82 104.7

SCRC-U08 –48.0 –7.10 5.5 3.76 4.57 –12.22 97.17

SCRC-U09 –39.3 –5.94 5.1 5.04 5.51 –14.82 102.4

SCRC-U10 –37.6 –5.63 4.8 4.93 5.67 –15.46 101.5

SCRC-U11 –28.6 –5.25 5.5 nc nc nc nc

SCRC-U12 –33.9 –5.31 5.4 nc nc nc nc

SCRC-U13 –36.4 –6.09 6.3 nc nc nc nc

SCRC-U14 –38.9 –5.97 6.7 nc nc nc nc

SCRC-U15 –39.8 –6.18 6.5 nc nc –20.20 95.12

1

 Maximum contaminant level thresholds 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.
Tables 73

Table 13. Results for analyses of dissolved gases detected in samples 

collected for the Southern Coast Range–Coastal (SCRC) Groundwater Ambient 

Monitoring and Assessment (GAMA) study, California, May to December 2008.

[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 table 3K. Samples from the 12 special study wells were analyzed for dissolved gases 

in water. GAMA identification number: SCRC-B, Basins study area grid well; SCRC-U, 

understanding well. Other abbreviations: μg/L, micrograms per liter; mg/L, milligrams per 

liter; na, not available; —, not detected]

GAMA

identification 

number

Carbon 

dioxide 

(mg/L) 

(00405)

Dissolved 

oxygen 

(mg/L) 

(62971)

Argon 

(mg/L) 

(82043)

Dissolved 

nitrogen 

gas 

(mg/L) 

(00597)

Methane 

(μg/L) 

(76994)

Threshold type na na na na na

Threshold level na na na na na

SCRC Grid wells (6 wells sampled)

SCRC-B23 19.62 7.13 0.92 30.27 —

SCRC-B27 17.61 4.39 0.89 29.84 —

SCRC-B28 19.51 4.40 0.68 21.78 —

SCRC-B29 41.86 0.30 0.79 30.36 0.62

SCRC-B30 16.34 10.26 1.07 37.23 —

SCRC-B36 15.88 8.33 0.99 35.46 —

SCRC Understanding wells (6 wells sampled)

SCRC-U04 67.94 4.91 0.74 23.29 3.87

SCRC-U06 14.46 6.64 0.89 28.93 —

SCRC-U07 27.91 14.58 1.25 51.11 —

SCRC-U08 12.09 6.23 0.91 27.96 —

SCRC-U09 26.16 6.40 0.81 27.76 —

SCRC-U10 26.56 5.58 0.70 23.65 —
74 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table 14. Gross alpha and gross beta radioactivity detected in samples collected for the South Coast Range–Coastal (SCRC) 

Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 the 39 slow wells were analyzed. Information about the analytes given in table 3J. 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 identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands 

study area grid well; SCRC-U, understanding well. Threshold type and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. 

Environmental Protection Agency maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level. Other 

abbreviations: CSU, 1-sigma combined standard uncertainty; pCi/L, picocuries per liter; –, not detected; ±, plus or minus; *, value above threshold 

level]s

GAMA 

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)

Threshold type 1 MCL-US MCL-US MCL-CA MCL-CA

Threshold level 15 15 50 50

Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC

SCRC Grid wells (32 wells sampled)

SCRC-B05 4.2 ± 1.3 1.5 4.7 ± 1.5 1.7 3.71 ± 0.47 0.60 3.82 ± 0.48 0.62

SCRC-B08 10.4 ± 1.9 1.4 5.4 ± 1.6 1.8 3.41 ± 0.45 0.57 6.11 ± 0.57 0.60

SCRC-B10 1.96 ± 0.68 0.68 — 1.4 2.82 ± 0.52 0.76 3.01 ± 0.53 0.75

SCRC-B11 — 2 1.8 2.5 ± 1.5 2.0 2.42 ± 0.71 1.2 3.38 ± 0.77 1.2

SCRC-B16 3.1 ± 1.8 2.5 — 2.2 3.68 ± 0.59 0.77 4.98 ± 0.66 0.86

SCRC-B21 — 3.9 — 3.3 7.9 ± 1.0 1.3 8.8 ± 1.4 2.1

SCRC-B22 2 9.7 ± 2.6 2.3 7.2 ± 2.2 2.2 5.4 ± 1.0 1.5 8.56 ± 0.93 1.1

SCRC-B23 3.45 ± 0.97 0.89 1.75 ± 0.77 0.84 2 3.15 ± 0.43 0.56 4.04 ± 0.52 0.68

SCRC-B26 — 4.1 – 3.1 9.2 ± 1.0 1.2 8.4 ± 1.1 1.4

SCRC-B27 2.0 ± 1.1 1.3 4.6 ± 1.2 1.1 3.67 ± 0.43 0.54 4.47 ± 0.56 0.74

SCRC-B28 1.77 ± 0.58 0.67 — 0.92 1.86 ± 0.49 0.77 1.8 ± 0.49 0.71

SCRC-B30 4.1 ± 1.5 1.7 — 1.7 3.6 ± 0.49 0.64 3.79 ± 0.46 0.58

SCRC-B34 5.6 ± 1.7 1.8 — 1.8 8.22 ± 0.67 0.61 6.57 ± 0.59 0.62

SCRC-B36 4.6 ± 1.4 1.7 2.7 ± 1.1 1.2 2.64 ± 0.37 0.48 4.5 ± 0.56 0.81

SCRC-B37 7.8 ± 2.1 1.9 — 2.2 6.1 ± 0.78 0.94 6.41 ± 0.83 1.0

SCRC-B39 5.1 ± 1.4 1.6 — 2.4 2.93 ± 0.4 0.52 3.97 ± 0.43 0.52

SCRC-H01 5.0 ± 1.4 1.2 4.2 ± 1.2 0.96 4.35 ± 0.84 1.2 3.3 ± 1.3 1.9

SCRC-H02 4.4 ± 1.2 1.1 3.0 ± 1.2 1.5 2.76 ± 0.41 0.54 5.17 ± 0.5 0.56

SCRC-H03 2.68 ± 0.8 0.86 – 1.0 5.16 ± 0.66 0.87 3.81 ± 0.83 1.3

SCRC-H04 2 8.1 ± 1.9 1.9 4.0 ± 1.4 1.5 4.48 ± 0.54 0.64 6.3 ± 0.61 0.65

SCRC-H05 4.83 ± 0.9 0.6 1.76 ± 0.63 0.71 2.39 ± 0.48 0.68 2.78 ± 0.48 0.68

Table 14. Gross alpha and gross beta radioactivity detected in samples collected for the South Coast Range–Coastal (SCRC) 

Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.

[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 the 39 slow wells were analyzed. Information about the analytes given in table 3J. 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 identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands study area grid well; SCRC-U, 

understanding well. Threshold type and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. Environmental Protection Agency 

maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level. Other abbreviations: CSU, 1-sigma 

combined standard uncertainty; pCi/L, picocuries per liter; –, not detected; ±, plus or minus; *, value above threshold level]
Tables 75

Table 14. Gross alpha and gross beta radioactivity detected in samples collected for the South Coast Range–Coastal (SCRC) 

Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—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 the 39 slow wells were analyzed. Information about the analytes given in table 3J. 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 identification number: SCRC-B, Basins study area grid well; SCRC-H, Uplands 

study area grid well; SCRC-U, understanding well. Threshold type and threshold level as of November 17, 2008. Threshold type: MCL-US, U.S. 

Environmental Protection Agency maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level. Other 

abbreviations: CSU, 1-sigma combined standard uncertainty; pCi/L, picocuries per liter; –, not detected; ±, plus or minus; *, value above threshold 

level]s

GAMA 

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)

Threshold type 1 MCL-US MCL-US MCL-CA MCL-CA

Threshold level 15 15 50 50

Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC

SCRC-H06 1.36 ± 0.62 0.67 — 1.1 2.49 ± 0.5 0.72 — 1.6

SCRC-H07 6.9 ± 1.4 0.94 3.3 ± 1.2 1.1 3.05 ± 0.72 1.0 2.99 ± 0.87 1.3

SCRC-H08 9.1 ± 1.8 1.3 3.9 ± 1.1 1.1 3.56 ± 0.43 0.54 4.91 ± 0.47 0.49

SCRC-H09 8.4 ± 1.4 0.98 4.6 ± 1.3 0.98 3.45 ± 0.87 1.4 5.12 ± 0.9 1.2

SCRC-H10 3.5 ± 1.5 2.0 4.7 ± 1.5 1.6 3.47 ± 0.82 1.2 4.89 ± 0.61 0.8

SCRC-H11 14.1 ± 2.3 1.6 11.1 ± 1.8 1.0 1.88 ± 0.48 0.71 6.06 ± 0.55 0.56

SCRC-H12 3.2 ± 1.1 1.1 8.0 ± 1.7 1.4 4.63 ± 0.46 0.50 4.26 ± 0.55 0.81

SCRC-H13 — 0.60 — 0.75 2.85 ± 0.43 0.61 2.89 ± 0.47 0.61

SCRC-H14 4.0 ± 1.3 1.5 1.8 ± 1.1 1.5 9.45 ± 0.79 0.78 6.3 ± 0.65 0.78

SCRC-H15 6.2 ± 1.4 1.4 4.5 ± 1.2 1.1 3.35 ± 0.58 0.8 4.78 ± 0.44 0.45

SCRC-H16 5.0 ± 1.2 0.96 — 2.7 2 5.27 ± 0.52 0.57 6.28 ± 0.65 0.86

SCRC Understanding wells (7 wells sampled)

SCRC-U03 *16.8 ± 2.8 1.5 11.5 ± 2.5 2.2 6.39 ± 0.65 0.74 13.5 ± 1.0 0.81

SCRC-U06 — 1.6 1.18 ± 0.81 1.1 3.12 ± 0.82 1.3 3.34 ± 0.82 1.3

SCRC-U07 11.2 ± 3.0 3.0 6.2 ± 2.2 2.5 3.4 ± 0.77 1.1 6.8 ± 1.4 1.9

SCRC-U08 4.2 ± 1.0 0.85 — 1.4 2.55 ± 0.62 0.92 2.85 ± 0.96 1.4

SCRC-U09 6.8 ± 2.2 2.5 3.2 ± 1.6 1.9 4.66 ± 0.7 0.92 4.66 ± 0.75 1.1

SCRC-U10 4.9 ± 2.4 3.1 4.7 ± 1.9 2.1 2.8 ± 0.72 1.0 4.78 ± 0.7 0.88

SCRC-U15 3.43 ± 0.7 0.38 1.55 ± 0.86 1.1 1.67 ± 0.36 0.52 2.31 ± 0.61 0.86

1

 Maximum contaminant level thresholds 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

 Counted 4-6 days after collection.
76 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Appendix 

This appendix includes discussions of the methods 

used to collect and analyze groundwater and surface-water 

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 quality-control data, and the results 

of the quality-control assessments also are discussed.

Sample Collection and Analysis

Groundwater samples were collected 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 Weiss (1968), Shelton and others (2001), 

McCleskey and others (2003), and Wright and others (2005). 

Prior to sampling, each well was pumped continuously 

to purge at least three casing-volumes of water from the well 

(Wilde and others, 1999). Wells were sampled using Teflon®

tubing with brass and stainless-steel fittings attached to a 

sampling point on the well discharge pipe as close to the 

well-head as possible. The sampling point always was located 

upstream of any well-head treatment system or water storage 

tank. For the fast schedule, samples were collected at the 

well head using a foot-long length of Teflon® tubing. For the 

slow schedule, the samples were either collected in the same 

manner as the fast schedule or collected inside an enclosed 

chamber located inside a mobile laboratory and connected to 

the well head by a 10–50 ft length of the Teflon® tubing (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, turbidity, and 

specific conductance. Turbidity was measured in the field with 

a calibrated turbidity meter. 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). All sensors 

on the multi-probe meter were calibrated daily. Measured 

temperature, dissolved oxygen, pH, specific conductance, and 

turbidity values were recorded at 5-min intervals for at least 

30 min, and when these values remained stable for 20 min, 

samples for laboratory analyses then were collected. 

Field measurements and instrument calibrations were 

recorded by hand on field record sheets and electronically in 

portable computer field forms (PCFF), a software package 

designed by the USGS with support from the GAMA 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. 

For analyses requiring filtered water, groundwater 

was diverted through a disk filter, a baked 0.7-μm nominal 

pore-size glass-fiber filter, or a 0.45-μm pore-size Whatman®

vented capsule filter, depending on the protocol for the 

analysis (Wilde and others, 1999, 2004). 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 2 or less with the appropriate acids using 

ampoules of certified, traceable concentrated acids obtained 

from the NWQL.

Temperature-sensitive samples were stored on ice prior 

to, and during daily shipping to the various laboratories. The 

non-temperature sensitive samples for tritium, dissolved noble 

gases, and stable isotopes of hydrogen and oxygen in water 

and of sulfur in dissolved sulfate were shipped monthly, while 

temperature- or time-sensitive samples for VOCs, pesticides 

and pesticide degradates, polar pesticides and metabolites, 

perchlorate, NDMA, 1,2,3-TCP, trace elements, nutrients, 

DOC, major and minor ions, silica, TDS, gross alpha and 

gross beta radioactivity, and dissolved gases were shipped 

daily. The temperature-sensitive samples for stable isotopes 

of carbon in dissolved inorganic carbon and carbon-14 

abundance, nitrogen and oxygen in dissolved nitrate, and 

arsenic and iron speciation were stored on ice, archived in a 

laboratory refrigerator and/or freezer, and shipped after results 

for alkalinity, nitrate, and the metal concentrations were 

received from the NWQL.

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 in the references for analytical methods listed 

in table A1; only brief descriptions are given here. Volatile 

organic compounds (VOC) samples were collected in 40-mL 

sample vials that were purged with three vial volumes of 

sample water before bottom filling to eliminate atmospheric 

contamination. 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 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 water, sealed with a conical 

cap, and secured with electrical tape to prevent leakage and 

evaporation.
Appendix 77

Pesticides and pesticide degradates, polar pesticides and 

metabolites, pharmaceutical compounds, and NDMA samples 

were collected in 1-L baked amber glass bottles. Pesticide 

and pharmaceutical samples were filtered through a 0.7-μm 

nominal pore-size glass fiber filter during collection, whereas 

the NDMA samples were filtered at Weck Laboratories, 

Inc. prior to analysis. Samples of NDMA were collected 

in containers treated with 0.05 g of sodium thiosulfate 

(Na2S2O3).

Groundwater samples for trace elements, major and 

minor ions, silica, TDS, and field alkalinity analyses required 

filling one 250-mL polyethylene bottle with untreated 

groundwater, and one 500-mL and one 250-mL polyethylene 

bottle with filtered groundwater (Wilde and others, 2004). 

Filtration was done using a 0.45-μm pore-size Whatman®

vented capsule filter. The 250-mL filtered sample then was 

preserved with 7.5-N nitric acid. Mercury samples were 

collected by filtering groundwater into a 250-mL glass bottle 

and preserving with 6-N hydrochloric acid. Arsenic and iron 

speciation samples were filtered into a 250-mL polyethylene 

bottle that was covered with tape to prevent light exposure and 

preserved with 6-N hydrochloric acid. Gross alpha and gross 

beta radiation samples were filtered into a 1-L polyethylene 

bottle and acidified with nitric acid. The nutrient and stable 

isotopes of nitrogen and oxygen in dissolved nitrate samples 

each were filtered into 125-mL brown polyethylene bottles. 

Stable isotopes of sulfur in dissolved sulfate samples were 

filtered into two 1-L polyethylene bottles. 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. Stable isotopes of carbon in 

dissolved inorganic carbon and carbon-14 abundance samples 

had no headspace and were sealed with a conical cap to avoid 

atmospheric contamination. Samples for field alkalinity 

titrations were collected by filtering groundwater into 500-mL 

polyethylene bottles.

DOC and the dissolved gases were collected from the 

hose bib at the well head, regardless of the sampling schedule 

(fast, slow, or special study). 

DOC was collected using a 50-mL syringe and Acrodisc®

0.45-μm disk filter. For each sample, 50-mL of blank water 

and 50-mL of groundwater were filtered through the apparatus 

before filtering 100-mL of groundwater into a125-mL baked 

glass bottle (Wilde and others, 2004). Each sample then was 

preserved immediately by lowering the pH to 2 with 4.5-N 

sulfuric acid.

Dissolved gases were collected by bottom filling two 

150-mL glass serum bottles that were first overfilled with 

approximately 5 gallons of groundwater. These samples had 

no headspace or air bubbles inside the bottles and were sealed 

underwater to avoid atmospheric contamination. 

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 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). 

Alkalinity was measured in the mobile laboratory at 

the well site on filtered samples by Gran’s titration method 

(Gran, 1952) or the incremental titration method (Barnes, 

1964; Yurewicz, 1981). Titration data were entered directly 

into PCFF and the concentrations of bicarbonate (HCO3–) 

and carbonate (CO3

2–) automatically were calculated from 

the titration data using the advanced speciation method. 

Concentrations of HCO3- and CO3

2– also were calculated from 

the laboratory alkalinity and pH measurements. Calculations 

were made in a spreadsheet using the advanced speciation 

method (http://or.water.usgs.gov/alk/methods.html) with 

pK1 = 6.35, pK2 = 10.33, and pKW = 14. 

Surface-water samples were collected from multiple 

vertical segments across the width of the river channel using 

depth- and width-integrated sampling methods described in 

the USGS National Field Manual (U.S. Geological Survey, 

variously dated). These methods provided a sample that was 

representative of the entire river cross-section. Sampling 

equipment consisted of a standard USGS depth-integrated 

DH-81 hand-held sampler. All surface-water samples were 

collected using the DH-81 sampler with Teflon® 1-L bottles, 

caps, and nozzles. Water samples for chemical analysis 

(trace elements, nutrients, major and minor ions, silica, TDS, 

alkalinity, and stable isotopes of nitrogen and oxygen in 

dissolved nitrate) were composited from the Teflon® bottles 

into a pre-rinsed Teflon® churn splitter and processed inside 

the mobile laboratory in the same fashion as the groundwater 

samples. Stable isotopes of hydrogen and oxygen in water 

samples were collected by dipping the 60-mL clear glass bottle 

at the river centroid. 

Nine laboratories performed chemical analyses for 

this study (table A1), although most of the analyses were 

performed at the NWQL or by laboratories contracted by the 

NWQL. The NWQL maintains a rigorous quality-assurance 

program (Pirkey and Glodt, 1998; Maloney, 2005). Laboratory 

quality-control 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 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 Office of Water 

Quality Branch of Quality Systems (BQS) within the USGS 

Office of Water Quality maintains independent oversight of 

quality assurance at the NWQL and laboratories contracted 

by the NWQL. The Branch of Quality Systems 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://qadata.

cr.usgs.gov/nfqa/). Results for analyses made at the NWQL or 
78 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

by laboratories contracted by the NWQL are uploaded directly 

into NWIS by the NWQL. 

Results from the USGS Branch of Quality Systems 

quality assurance program indicate negative analytical 

biases for boron and iron (each of 12 percent) and positive 

analytical biases for cadmium and uranium (of developing and 

9.7 percent, respectively) during the time that SCRC samples 

were analyzed at the NWQL (U.S. Geological Survey Branch 

of Quality Systems, December 2008). The results suggest that 

boron and iron concentrations may be slightly underestimated 

and cadmium and uranium concentrations may be slightly 

overestimated. 

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 the laboratory reporting level 

(LRL) as a threshold 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 long-term method 

detection level (LT-MDL). The LT-MDL is derived from 

the standard deviation of at least 24 method detection limit 

(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 1 percent chance of a false positive). LT-MDLs 

continually are monitored and updated (Childress and others, 

1999; U.S. Environmental Protection Agency, 2002). The 

USGS NWQL updates LRL values regularly and the values 

listed in this report were in effect during the period that 

analyses were made for groundwater samples from the SCRC 

study (May to December 2008).

Detections 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 high 

certainty of detection, but the precise concentration is 

uncertain. Information-rich methods are those that utilize gas 

chromatography or high-performance liquid chromatography 

(HPLC) with mass spectrometry detection (VOCs, pesticides, 

and polar pesticides). Compounds are identified by 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 quality-control criteria and from samples that were 

diluted prior to analysis (Childress and others, 1999).

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 method uncertainty 

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 or MRL values provided by the analyzing laboratories. 

Results for some constituents are presented using raised study 

reporting limits (SRLs) derived from assessment of data from 

quality-control samples associated with groundwater samples 

collected as part of the GAMA Priority Basins Project. The 

SRLs were determined by statistical assessment of results from 

the field blanks collected during the first 21 GAMA Priority 

Basins Project study units (May 2004 through January 2008) 

(Olsen and others, 2010). The statistical analysis used order 

statistical and binomial probabilities to construct an upper 

confidence limit for the amount of contamination potentially 

present in field blanks, and by inference, in groundwater 

samples (Hahn and Meeker, 1991). The upper confidence limit 

is the maximum concentration of a constituent for which there 

is a 90-percent confidence that no more than 10 percent of 

the groundwater samples might have a higher concentration 

of that constituent solely as a result of contamination of the 

groundwater sample during sample collection, handling, and 

analysis. This maximum concentration corresponds to the 

concentration in the field blank that is at the 95th percentile of 

the 86 field blanks used in the statistical assessment. For most 

constituents, this maximum concentration was less than the 

LRL or MRL for the constituent. Data for such constituents 

are reported with the LRL or MRL. For some constituents, this 

maximum concentration was greater than the LRL or MRL. 

An SRL then was defined as equal to the concentration in the 

95th percentile field blank. Detections of those constituents 

reported by the laboratory with concentrations greater than the 

LRL or MRL but less than the SRL are reported in the tables 

with a less than or equal to (≤) symbol preceding the reported 

value.

The methods used for analysis of radiochemical 

constituents (gross alpha radioactivity and gross beta 

radioactivity) measure activities by 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 
Appendix 79

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 

nondetections. 

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) (table 14). 

Specifically, activities of gross alpha and gross beta radiation 

are reported with sample-specific CSU. The CSU is reported at 

the 68 percent confidence level (1-sigma). 

Notation

Stable isotopic compositions of oxygen, hydrogen, 

nitrogen, carbon, and sulfur are reported as relative isotope 

ratios in units of per mil using the standard delta notation 

(Coplen and others, 2002):

di eE

R

R

i

= − ×





 



 sampl

reference

 per mil

where 

is the at

1 1, 000

omic mass of the heavier isotope of

element 

is the elemen

,

E t (O for oxygen, C for carbon, 

N for nitrogen, H for hydrogen, and 

S for sulfur),

is the ratio of the abundanc sample R e of the heavier 

isotope of the element ( O, C, N, 18

2

13 15

H, S) to the lighter isotope of the

element, ( O, C,

34

16 12 N, H, S) in 

the sample and,

is the ratio o

14 1 32

reference R f the abundance of the heavier 

isotope of the element to the lighter isotope

of the element in the reference material.

The reference material for oxygen and hydrogen is 

Vienna Standard Mean Ocean Water (VSMOW), which is 

assigned δ18O and δ2H values of 0 per mil (note than δ2H is 

sometimes written as δD because the common name of the 

heavier isotope of hydrogen, hydrogen-2, is deuterium). The 

reference material for carbon is Vienna Pee Dee Belemnite 

(VPDB), which is assigned a δ13C value of 0 per mil. The 

reference material for nitrogen is atmospheric nitrogen gas, 

which is assigned a δ15N value of 0 per mil. The reference 

material for sulfur is Vienna Canon Diablo Troilite (VCDT), 

which is assigned a δ34S value of 0 per mil. Positive values 

indicate enrichment of the heavier isotope and negative values 

indicate depletion of the heavier isotope, compared to the 

ratios observed in the standard reference material.

Constituents on Multiple Analytical Schedules

Twelve constituents targeted in this study were measured 

by more than one analytical schedule 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). Methods 

with full approval are preferred over those with provisional 

approval and approved methods are favored over research 

methods. The method with greater accuracy and precision 

and lower LRLs for the overlapping constituents generally 

is preferred. However, the method with higher LRLs may be 

selected as the preferred method to provide consistency with 

historical data analyzed by the same method.

Some of 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 for all three constituents (pH, specific conductance, 

and alkalinity) because groundwater samples change once they 

are removed from the ambient environment; however, both 

measurements are reported.

Metalaxyl (a fungicide) was measured by two analytical 

schedules (2003 and 2060) at the NWQL and data from both 

methods are reported. 

For arsenic and iron concentrations, the approved 

method, Schedule 1948, used by the NWQL is preferred 

over the research methods used by the USGS Trace Metal 

Laboratory. The concentrations measured by the Trace Metal 

Laboratory only are used to calculate ratios of redox species 

for each element, As(V)

As(III)

 for arsenic and Fe(III)

Fe(II)

 for iron. For 

example:

Fe(III)

Fe(II)

Fe(T) Fe(II)

Fe(II)

where 

Fe(T) is the total i

= −

ron concentration (measured),

Fe(II) is the concentration of ferrous iron (measured), and

Fe(III) is the concentration of ferric iron (calculated).

Tritium also is measured at two laboratories—Lawrence 

Livermore National Laboratory (LLNL) and U.S. Geological 

Survey Stable Isotope and Tritium Laboratory (SITL)—but 

only the data from SITL were available for reporting at the 

time of this publication.
80 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Quality Assurance

The purpose of quality assurance is to identify which 

data best represent environmental conditions and which may 

have been affected by contamination or bias during sample 

collection, processing, storage, transportation, or laboratory 

analysis. Four types of quality-control (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. Results that were found to have 

significant contamination bias, on the basis of the QC data 

collected from this study and previous studies, were flagged 

with an appropriate remark code (described in subsequent 

sections) and rejected from subsequent use, including 

calculations of detection frequency. 

The quality-assurance protocols 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 quality-assurance 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). 

Blanks

The primary purposes of collecting blanks are to evaluate 

the magnitude of potential contamination of samples with 

analytes of interest during sample handling or analysis and to 

identify and mitigate these sources of sample contamination. 

Blank Collection and Analysis

Blanks were collected using blank water certified by the 

NWQL to contain less than the LRL 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 blanks of organic constituents and inorganic-free 

blank water was used for blanks of other constituents. For 

SCRC, field and source-solution blanks were collected at up 

to 12 percent of the wells sampled and one equipment blank 

collected. 

Field blanks were collected to assess potential 

contamination of samples during collection, processing, 

transport, and analysis. Source-solution blanks were collected 

to assess potential contamination of samples during transport 

and analysis, and potential contamination of the certified 

blank water obtained from the USGS NWQL. The equipment 

blank was collected at the USGS San Diego Projects Office to 

assess potential contamination of groundwater samples during 

collection by the Keck SP submersible sampling pump, which 

was used for the sampling of the environmental monitoring 

wells in the SCRC study unit. 

Field blanks were analyzed for VOCs, pesticides and 

pesticide degradates, polar pesticides and metabolites, 

pharmaceuticals, perchlorate, NDMA, 1,2,3-TCP, trace 

elements, nutrients, DOC, major and minor ions, silica, 

TDS, arsenic and iron speciation, and gross alpha and gross 

beta radioactivity. Source-solution blanks were analyzed for 

VOCs, pharmaceuticals, perchlorate, NDMA, 1,2,3-TCP, trace 

elements, major and minor ions, silica, TDS, and arsenic and 

iron speciation. The equipment blank was analyzed for VOCs, 

pesticides and pesticide degradates, polar pesticides and 

metabolites, pharmaceuticals, perchlorate, NDMA, 1,2,3-TCP, 

trace elements, nutrients, DOC, major and minor ions, silica, 

TDS, and gross alpha and gross beta radioactivity. 

Blanks were not collected for tritium or dissolved gases. 

Tritium and dissolved gases are in the atmosphere and would 

dissolve into any solution used in collecting a blank, making 

it impractical to collect a blank for these analytes. Stableisotopic ratios of carbon, hydrogen, oxygen, nitrogen, and 

sulfur are an intrinsic property of any of these elements; 

therefore, the concept of a blank does not apply to these ratios.

For field blanks, blank water either was pumped or 

poured through the sampling equipment (fittings and tubing) 

used to collect groundwater, then processed and transported 

using the same protocols used for the groundwater samples. 

Source-solution blanks were collected at the sampling site 

by pouring blank water directly into sample containers that 

were preserved, stored, shipped, and analyzed in the same 

manner as the groundwater samples. For the equipment blank, 

blank water was pumped through the Keck SP submersible 

sampling pump and Teflon® sample tubing, then processed and 

transported using the same protocols used for the groundwater 

samples. Eight to 12 liters of blank water were pumped or 

poured through the sampling equipment before each field 

and/or equipment blank was collected.

Assessment of Blank Results

Contamination in blanks may originate from several 

different types of sources that require different strategies 

for assessment of potential contamination of groundwater 

samples during sample collection, handling, and analysis. 

Four primary modes of contamination are assessed in the 

event of detections in blanks or atypical results in groundwater 

samples: (1) impurities in the water used to collect the blanks, 

(2) contamination during sample collection and handling from 

a known source or condition present at the field site, (3) carryover of material on the sampling equipment from one sample 

to the next sample, (4) systematic and random contamination 

from field and laboratory equipment and processes. The fourth 

source of contamination (systematic and random) is being 

addressed using a larger set of field blank results from multiple 

studies in addition to the results from blanks collected from 

SCRC. The development of this approach and its methods are 

described by Olsen and others (2010).
Appendix 81

The first potential mode evaluated is the presence of 

impurities in the water used to collect the blank. Because 

the blanks were collected using blank water certified by the 

NWQL to contain less than the LRL or MRL of the analytes 

investigated in the study, the blank water is rarely the source 

of constituents detected in blanks. However, blank water 

sometimes is used before the certification process has been 

completed; thus, the certificates of analysis always must be 

checked. Blank water used in the GAMA SCRC was certified 

by the NWQL prior to blank collection.

The second potential mode evaluated is contamination 

from identifiable, known sources present at a specific field site. 

Contamination from specific sources may produce distinctive 

patterns of detections in blanks and groundwater samples, 

particularly for the VOCs. Substances that may be encountered 

at the field site, such as cements used on PVC-piping, contain 

recognizable associations of VOC constituents. For example, 

cements used on PVC-piping are primarily composed of 

tetrahydrofuran with lesser amounts of acetone and methyl 

ethyl ketone (2-butanone). However, detection of these 

recognizable associations of VOC constituents in groundwater 

samples does not necessarily indicate contamination during 

sample collection because these VOC constituents also may 

occur together in groundwater.

If a recognizable association of VOC constituents was 

detected in a blank or in a groundwater sample, then the field 

notes and photographs from the site at which the sample was 

collected were examined for presence of conditions that may 

have resulted in contamination of the blank or groundwater 

sample during sample collection. If the constituents were 

present in the blank and groundwater sample from the 

same site at similar concentrations and the field notes or 

photographs indicated that the probable contaminant source 

was present, then the detections of those constituents in the 

groundwater sample were V-coded and all other groundwater 

samples collected at sites where the same condition may have 

occurred were considered for V-coding. If the constituents 

were present in a groundwater sample and not the associated 

blank, or a groundwater sample from a site where no blanks 

were collected, and the field notes or photographs indicated 

that the presence of conditions that may have resulted in 

contamination of the groundwater sample during sample 

collection, the data were considered for V-coding. If no 

conditions that may have resulted in contamination of the 

groundwater sample during sample collection were identified 

in the field notes or photographs, then V-codes were not 

applied. 

The third potential mode of contamination that was 

evaluated was carry-over from the previous groundwater 

sample or blank collected with the same equipment. Carryover between samples is rare because the procedures used to 

clean the equipment between samples have been developed 

and extensively tested to assure that carry-over is mitigated as 

much as possible. Potential carry-over was evaluated 

using time-series analysis to look for patterns suggestive 

of carry-over of constituents from a sample with high 

concentrations to the next groundwater sample or blank 

collected with the same equipment. If nondetections were 

reported in blanks or groundwater samples collected after 

the collection of groundwater samples containing high 

concentrations of the constituent, then carry-over as a mode of 

contamination was ruled out. 

The fourth potential mode of contamination that was 

evaluated was random or systematic contamination from 

field or laboratory equipment or processes. All detections in 

blanks that could not be accounted for by impurities in the 

source-solution water, by specific known conditions at field 

sites, or by carry-over between samples were evaluated for 

random contamination. Random contamination in field and 

laboratory processes has an equal chance of affecting each 

groundwater sample; thus, strategies for flagging detections of 

constituents that are subject to random contamination in field 

and laboratory processes must be applied to all groundwater 

samples. 

Different notation was used for flagging detections 

of organic and inorganic constituents that may have been 

subjected to contamination during sample collection, 

handling, and analysis. Inorganic constituents naturally are 

present in groundwater and the concerns about inorganic 

constituents generally are related to concentration, rather than 

to detection (presence or absence). In contrast, concerns about 

organic constituents generally are related to both detection 

and concentration. Therefore, different schemes are used 

for assessing and flagging data for organic and inorganic 

constituents.

For organic constituents, V-codes were applied. The 

purpose of V-coding was to flag detections that have a greater 

chance of being false-positive detections. A false-positive 

detection is a detection that is caused by contamination during 

sample collection, handling, and analysis of a groundwater 

sample that would otherwise have a non-detection for that 

constituent. Results with V-codes were not considered 

detections of the constituent for this study and were not 

included in calculations of detection frequencies for organic 

constituents (tables 5, 9, and A3).

The V-coding level was defined as the highest 

concentration of the constituent detected in a field blank plus 

the LT-MDL (equal to one-half the LRL) for that constituent. 

Detections of the constituent in groundwater samples at 

concentrations less than this V-coding level were flagged 

with a V preceding the reported value in the data tables. The 

highest concentration measured in a blank was assumed to 

represent the highest potential amount of contamination. Thus, 

the V-code flags the results that could have changed from 

non-detection to a detection, relative to the LT-MDL, because 

of contamination. Results with V-codes were not considered 

detections of the constituent for this study and were not 

included in calculations of detection frequencies for organic 

constituents.
82 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

For inorganic constituents, a less than or equal to symbol 

(≤) was used to identify low-concentration detections of 

constituents that may have been affected by contamination. 

The ≤ symbol signifies that the concentration of the 

constituent in the groundwater sample is less than or equal to 

the measured concentration (including the possibility that it 

may be less than the LT-MDL and, therefore, a non-detection). 

For select trace elements (aluminum, barium, chromium, 

copper, lead, manganese, mercury, nickel, tungsten, vanadium, 

and zinc), the concentration cutoff, hereinafter referred to as 

the study reporting limit, SRL, for applying the ≤ symbol was 

determined from a statistical assessment of results for 86 field 

blanks collected between May 2004 and January 2008. The 

concentration threshold for applying the ≤ symbol was equal 

to the concentration of the field blank ranked at the 90 percent 

confidence level for the 90th percentile of the binomial 

distribution of the 86 field blanks (Olsen and others, 2010). 

For all other inorganic constituents, the SRL for applying 

the ≤ symbol was determined from assessment of the blanks 

collected in SCRC and was defined as equal to the highest 

concentration measured in the seven blanks collected in SCRC 

(blanks were collected at 10 percent of the wells sampled). 

In the data tables, a ≤ symbol preceded measured values that 

were less than the threshold concentration (tables 8 and A3). 

Future reports in this series will use the approach of Olsen and 

others (2010) for all inorganic constituents. 

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 due to differences in 

groundwater quality or to variability that may result from 

collecting, processing and analyzing the samples. Replicate 

analyses were made on up to 12 percent of the samples 

collected in the SCRC study unit (tables A4A–C).

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 

LRL for each constituent. 

 For this study, acceptable precision for replicate sample 

pairs is defined as follows:

• For concentrations less than five times the LRL 

(<5 LRL), an SD of less than 10 percent is acceptable.

• For concentrations greater than (or equal to) five times 

the LRL (≥5 LRL), an RSD of less than 10 percent is 

acceptable. For comparison, an RSD of 10 percent is 

equivalent to a relative percent difference (RPD) of 

14 percent. 

• For activities of radiochemical constituents, the 

presence of overlap between the results (value ± 

1-sigma CSU) is 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 the data are used for the purposes of 

comparison. If measured concentrations are slightly above 

a water-quality threshold, then actual concentrations could 

be slightly below that threshold. Similarly, if measured 

concentrations are slightly below a water-quality threshold, 

then actual concentrations could be slightly above. 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. 

For organic and inorganic constituents (except for 

radiochemical constituents), if both values for a replicate 

sample pair were reported as detections, then the SD was 

calculated if the mean concentration was <5 LRL for 

the constituent or the RSD was calculated if the mean 

concentration was ≥5 LRL for the constituent. If both values 

were reported as nondetections, then the variability was set 

to zero by definition. Cases other than two detections or two 

nondetections were treated as follows:

• For organic constituents, if one or both values were 

assigned a V-code, then neither SD nor RSD was 

calculated. A V-code indicates that the constituent was 

detected in blanks and was excluded from the dataset 

of groundwater-quality results. The data might not 

represent the concentration of the constituent in the 

groundwater sample.

• For organic and inorganic constituents, if one value 

was reported as a non-detection, and the other value 

was reported as a detection less than the LRL, then 

a value of zero was substituted for the non-detection 

and the SD calculated. Substituting zero for the nondetection yields the maximum estimate of variability 

for the replicate pair. 
Appendix 83

• For inorganic constituents, if one value for a sample 

pair was reported as a non-detection and the other 

value was reported as a ≤-coded value less than the 

SRL, or if both values were reported as ≤-coded 

values less than the SRL, then neither SD nor 

RSD was 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. 

• For organic and inorganic constituents, if one value 

was reported as a non-detection and the other value 

was reported as a detection greater than the LRL, 

then the variability for the pair was considered 

unacceptable.

Matrix Spikes

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 were 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 MCL; a low recovery could 

result in a falsely measured concentration less than the MCL, 

whereas a high recovery could result in a falsely measured 

concentration greater than the MCL.

The GAMA Priority Basins Project defined the dataquality objective range for acceptable matrix-spike recoveries 

as 70 to 130 percent. Only constituents with matrix spike 

recoveries outside of this range were flagged as having 

unacceptable recoveries; they were in tables 3B and 3C. 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 (Conner 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 spikes were performed for VOCs, pesticides 

and pesticide degradates, polar pesticides and metabolites, 

pharmaceuticals, perchlorate, NDMA, 1,2,3-TCP, and gross 

alpha and gross beta radioactivity because the analytical 

methods for these constituents may be susceptible to matrix 

interferences. Replicate samples for matrix-spike additions 

were collected at approximately 11 percent of the wells 

sampled although not all analyte classes were tested at every 

well (tables A5A–E).

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 to all groundwater and quality-control samples that 

were analyzed for VOCs, pesticides and pesticides degradates, 

and polar pesticides and metabolites (table A6). Most of the 

surrogate compounds are deuterated analogs of compounds 

being analyzed. For example, the surrogate toluene-d8 that is 

used for the VOC analytical method has the same chemical 

structure as toluene, except that the eight hydrogen-1 atoms on 

the molecule have been replaced by deuterium (hydrogen-2). 

Toluene-d8 and toluene behave very similarly in the analytical 

procedure, but the small mass difference between the two 

results in slightly different chromatographic retention times; 

thus, the use of a toluene-d8 surrogate does not interfere with 

the analysis of toluene (Grob, 1995). Only 0.015 percent of 

hydrogen atoms are deuterium (Firestone and others, 1996); 

thus, deuterated compounds like toluene-d8 do not occur 

naturally and are not detected in environmental samples. 

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 

DOC) 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).

Quality-Control Results

Detections in Field and Source-Solution Blanks 

and Equipment Blank

Field and source-solution blanks were collected at up 

to approximately 12 percent of the sites sampled in SCRC. 

Table A3 presents a summary of detections in the field and 

source-solution blanks and the equipment blank. 
84 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

1,2,4-Trimethylbenzene, toluene, and 1,1-Dichloroethene 

(1,1-DCE) were the only VOCs detected in blanks that 

also were detected in groundwater samples. Detections 

of 1,2,4-trimethylbenzene also were reported in blanks 

from other GAMA Priority Basins Project study units. 

Concentrations of 1,2,4-trimethylbenzene between E0.02 

and 0.56 μg/L were detected in approximately 5 percent 

of the field and source-solution blanks from the 27 GAMA 

Priority Basins Project study units sampled to date from 

2004 through 2008 (Kulongoski and others, 2006, 2007; 

Dawson and others, 2008; Schmitt and others, 2008; Fram 

and others, 2009; Kent and Belitz, 2009). Approximately 

91 percent of the concentrations of 1,2,4-trimethylbenzene 

detected in groundwater samples from the 27 GAMA Priority 

Basins Project study units sampled to date were less than or 

equal to 0.12 μg/L (greater than the concentration detected 

in the SCRC field blank, 0.08 μg/L). The source of the 

1,2,4-trimethylbenzene is unknown. The concentrations 

at which 1,2,4-trimethylbenzene was detected in both the 

groundwater samples and the blanks suggest that groundwater 

samples and blanks were randomly contaminated with 

1,2,4-trimethylbenzene from an unknown source while being 

collected, handled, transported, and/or analyzed. Because the 

source of the 1,2,4-trimethylbenzene in blanks is unknown and 

the pattern of detections in blanks and groundwater samples 

from other GAMA Priority Basins Project study units sampled 

to date indicates the potential for random contamination, 

1,2,4-trimethylbenzene detections in groundwater samples 

collected in all GAMA Priority Basins Project study units 

are subject to V-coding. As a result, concentrations of 

1,2,4-trimethylbenzene detected in 18 groundwater samples in 

SCRC were V-coded as nondetections (tables 5 and A3). 

The blank detections in SCRC for toluene, and 1,1-DCE 

also were considered to be random contamination, which 

has an equal chance of affecting each groundwater sample. 

Therefore, strategies for flagging detections of constituents 

that are subject to random contamination must be applied to 

all groundwater samples. Toluene was detected in two field 

blanks at concentrations of 0.18 and E0.03 μg/L. The former 

of these detections created a V-coding level of 0.19 μg/L 

(0.18 μg/L plus one-half the LRL of 0.02 μg/L). Toluene was 

detected at concentrations less than the V-coding level in two 

groundwater samples and both detections were V-coded as 

nondetections (tables 5 and A3). 1,1-DCE was detected in one 

source-solution blank at E0.03 μg/L. This detection created 

a V-coding level of 0.04 μg/L (E0.03 μg/L plus one-half the 

LRL of 0.02 μg/L). None of the 1,1-DCE concentrations 

measured for groundwater samples were less than 0.04 μg/L; 

therefore, values were not V-coded (table 5).

Trace-element data were assessed for potential flagging 

of results using the GAMA study reporting limits (SRLs), 

which are based on results for 86 field blanks collected 

between May 2004 and January 2008 in conjunction with the 

three field and source-solution blanks collected in SCRC and 

the single equipment blank. Aluminum, barium, chromium, 

copper, lead, manganese, mercury, nickel, tungsten, vanadium, 

and zinc have SRLs previously determined by the field blank 

study described in the appendix section titled “Assessment 

of Blank Results.” Measured values that are less than the 

SRL are flagged with a ≤ symbol in table 8. Field and sourcesolution blanks were collected at 3 of the 42 groundwater 

sites sampled, in conjunction with the equipment blank, for 

analysis of trace elements. Five trace elements were detected 

in one blank; chromium (2.2 μg/L), copper (2.3 μg/L), 

lead (0.31 μg/L), nickel (0.25 μg/L), and zinc (11.5 μg/L) 

(table A3). All detections of these trace metals less than their 

SRL levels were flagged with a ≤ symbol (tables 8 and A3). 

There were no other trace metals detected in any of the blanks 

in the SCRC.

Field blank and source-solution blanks were collected 

at 3 of the 45 groundwater sites sampled, in conjunction with 

the equipment blank for analysis of nutrients. Field blanks 

were collected at 3 of the 37 groundwater sites sampled for the 

analysis of DOC. 

All nutrient and DOC blank detections in the SCRC were 

considered to be random contamination, which has an equal 

chance of affecting each water sample. Therefore, strategies 

for flagging detections of constituents that are subject to 

random contamination must be applied to all water samples. 

Ammonia (as nitrogen) was detected in one field blank 

at a concentration of E0.01 mg/L, creating a V-coding level of 

0.02 mg/L (0.01 mg/L plus one-half the LRL of 0.02 mg/L). 

Ammonia (as nitrogen) was detected at a concentration of 

E0.02 mg/L in one grid well sample (SCRC-H08) and one 

surface-water sample (SCRC-SW1) (table 9). The measured 

concentration of total nitrogen from SCRC-H08 equaled the 

sum of all filtered nitrogen analytes (ammonia + nitrate + 

nitrite + organic-nitrogen); therefore, the field blank detection 

was not of potential concern for this sample (table 9). The 

sampling equipment used in the collection of surface-water 

samples is markedly different than the sampling equipment 

used in the collection of groundwater and field-blank samples. 

As a result, the field-blank detection of ammonia (as nitrogen) 

was not of potential concern for the SCRC-SW1 sample 

(table 9). 

Total nitrogen (ammonia + nitrate + nitrite + organicnitrogen) was detected in one field blank at a concentration of 

0.12 mg/L, creating a V-coding level of 0.15 mg/L (0.12 mg/L 

plus one-half the LRL of 0.06 mg/L). Total nitrogen was 

detected at a concentration less than the V-coding level in 

four groundwater samples in SCRC. The sum of the filtered 

nitrogen analytes (ammonia + nitrate + nitrite + organicnitrogen) was equal to or within 10 percent relative percent 

difference (U.S. Geological Survey National Water Quality 

Laboratory acceptance criteria for total nitrogen and the 

sum of the filtered nitrogen analytes) of the measured 

concentration of the associated total nitrogen result; therefore, 

the blank detection was not of potential concern for these four 

groundwater samples (table 9).
Appendix 85

Phosphate, orthophosphate (as phosphorus) was detected 

in the equipment blank at a concentration of E0.004 mg/L, 

creating a V-coding level of 0.007 mg/L (E0.004 mg/L plus 

one-half the LRL of 0.006 mg/L). Equipment blank detections 

potentially can affect only the groundwater samples collected 

with the Keck SP submersible sampling pump, which was 

used for the sampling of the environmental monitoring wells 

in SCRC. Phosphate was not detected in groundwater samples 

from the environmental monitoring wells. Orthophosphate 

(as phosphorus) concentrations were less than 0.007 mg/L; 

therefore, values were not V-coded as a result of the 

equipment-blank detection (table 9).

DOC was detected at a concentration of E0.3 mg/L in 

one field blank and low concentrations of DOC were detected 

in field blanks collected in previous GAMA Priority Basins 

Project study units (Bennett and others, 2006; Kulongoski and 

Belitz, 2007; Mathany and Belitz, 2009). Thus, the data for all 

groundwater samples with concentrations equal to or less than 

E0.5 mg/L (0.3 mg/L plus one-half the LRL of 0.4 mg/L) were 

V-coded as nondetections (tables 9 and A3).

Field and source-solution blanks were collected at 3 of 

the 42 groundwater sites in SCRC in conjunction with the 

equipment blank for analysis of major and minor ions, silica, 

and TDS. Chloride was detected in one field blank resulting 

in a study reporting limit (SRL) at 0.48 mg/L. This blank 

detection was considered to be random contamination, which 

has an equal chance of affecting each groundwater sample; 

thus, none of the choride concentrations in all groundwater 

samples less than the SRL value were subject to flagging. 

None of the chloride concentrations in groundwater samples 

were less than 0.48 mg/L; therefore, none of the values were 

flagged with a ≤ symbol (table 10). Silica was detected in 

two field blanks resulting in a SRL at E0.013 mg/L (the 

higher of the two detected concentrations, E0.013 mg/L and 

E0.012 mg/L) . This blank detection also was considered to 

be random contamination; thus, all silica concentrations in 

groundwater samples less than the SRL value were subject 

to flagging. None of the silica concentrations in groundwater 

samples were less than E0.013 mg/L; therefore, none of the 

values were flagged with a ≤ symbol (table 10).

Constituents were not detected in the blanks for the 

following analyte groups: pesticides and pesticide degradates 

(six field blanks and one equipment blank); polar pesticides 

and metabolites (six field blanks and one equipment blank); 

perchlorate (six field blanks, seven source-solution blanks, 

and one equipment blank); NDMA (three field blanks, four 

source-solution blanks, and one equipment blank); 1,2,3-

TCP (six field blanks, seven source-solution blanks, and 

one equipment blank); arsenic and iron species analysis at 

the USGS Trace Metal Laboratory (three field blanks and 

one source-solution blank); and gross alpha and gross beta 

radioactivity (72-hour and 30-day counts) (two field blanks 

and one equipment blank). 

Variability in Replicate Samples

Tables A4A–C summarize the results of replicate 

analyses for constituents detected in groundwater samples 

collected in the SCRC. Of the 1,968 replicate pairs of 

constituents analyzed, 537 were for constituents detected in 

at least one groundwater sample. Of these 537 pairs, 2 pairs 

(boron and iron [total]) were outside the limits for acceptable 

precision. Results for replicate analyses for constituents that 

were not detected are not reported in tables A4–C. 

Eight replicate pairs of samples were analyzed for 

the 85 VOCs and all pairs yielded two values reported as 

nondetections with the exception of four replicate pairs 

of 1,2,4-Trimethylbenzene and one replicate pair each of 

dichlorodifluoromethane (CFC-12), trichlorofluoromethane 

(CFC-11), and tetrachloroethene. 

All four replicate pairs for 1,2,4-Trimethylbenzene 

consisted of values reported as one non-detection and one 

detection greater than the LRL (0.04 μg/L). All four of these 

replicate pairs yielded V-coded values (tables 5 and A4A). 

Variability was not assessed for the four pairs with V-coded 

data because the data are not considered representative of the 

composition of the groundwater.

The replicate pair for dichlorodifluoromethane 

(CFC-12), perchloroethene (PCE, tetrachloroethene), and 

trichlorofluoromethane (CFC-11) yielded two values reported 

as detections and all replicate pair analysis resulted in SDs 

within acceptable precision (table A4A). 

All eight replicate pairs for the 63 pesticide and 

pesticide degradate compounds were analyzed and produced 

nondetections with the exception of one replicate pair 

of 1-Naphthol. This replicate pair had one non-detection 

and one detection of E0.006 μg/L, well below the LRL of 

0.04 μg/L. Following replicate analysis procedures explained 

in section, “Assessment of Replicate Variability,” a value 

of zero was assigned to the non-detection and the SD of the 

replicate pair then was calculated. This replicate pair analysis 

resulted in an SD within the acceptable range of less than 

10 percent. 1-Naphthol was not detected in any groundwater 

samples; therefore this replicate analysis is not represented in 

table A4A. 

Eight replicate pairs for the 60 polar pesticide and 

metabolite compounds were assessed and all pairs consisted 

of nondetections with the exception of one replicate pair of 

Deethylatrazine (2-Chloro-4-isopropylamino-6-amino-striazine), which had one non-detection and one detection less 

than the LRL. The replicate pair analysis resulted in an SD 

within the acceptable range for this deethylatrazine replicate 

pair. Deethylatrazine was not detected by the NWQL on the 

analytical Schedule 2060; therefore, this replicate analysis is 

not reflected in table A4A. 
86 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Replicate pairs for the constituents of special interest 

(perchlorate [seven pairs], NDMA [seven pairs], and 1,2,3-

TCP [five pairs]) were analyzed at Weck Laboratories, Inc., 

for variability. Five of the seven replicate pairs for perchlorate 

consisted of two values reported as detections and all analysis 

resulted in SDs or RSDs within the acceptable range of less 

than 10 percent (table A4A). The two remaining replicate 

pairs for perchlorate and all replicate pairs for NDMA and 

1,2,3-TCP were yielded `two values reported as nondetections. 

Replicate pairs of samples were analyzed for trace 

elements (five pairs), nutrients (one to six pairs), major and 

minor ions (five to six pairs), silica (six pairs), TDS (six pairs), 

alkalinity (five pairs), and isotope tracers (three to nine 

pairs), and the SD or RSD values for all pairs were within the 

acceptable range of less than 10 percent with the exception 

of one replicate pair of boron (table A4B). The RSD value 

for the replicate pair for boron was 19 percent; however, the 

environmental concentration was just greater than one-third 

and the replicate sample concentration was just greater than 

one-half of the corresponding NL-CA (tables 3F and 8). 

The less than acceptable precision for this constituent at 

concentrations less than health-based thresholds will not affect 

the assessments of groundwater quality being made by the 

GAMA Priority Basins Project. 

Five replicate pairs were analyzed for species of arsenic 

and iron by the USGS Trace Metals Laboratory in Boulder, 

Colorado. One replicate pair analyzed for arsenic (total), 

three pairs of species of arsenic (III), and two pairs of iron 

(II) yielded two non-detection values. Four replicate pairs 

analyzed for arsenic (total), two pairs of species of arsenic 

(III), four pairs of arsenic (III), and two pairs of iron (II) 

consisted of two values reported as detections, and all replicate 

pair analysis resulted in SDs or RSDs within acceptable 

precision with the exception of one replicate pair of iron 

(total) (table A4B). The RSD value for this replicate pair was 

22 percent; however, this less than acceptable precision for 

this constituent is not of potential QC concern for the GAMA 

Priority Basins Project. As explained in the appendix section 

titled “Constituents on Multiple Analytical Schedules,” iron 

concentrations reported from the NWQL are preferred over the 

research methods used by the USGS Trace Metal Laboratory. 

The remaining replicate pairs (one for iron [total] and one for 

iron [II]) each produced one non-detection and one detection 

reported at concentrations greater than the LRL. These less 

than acceptable results are not of QC concern for the GAMA 

Priority Basins Project because values generated from the 

NWQL are preferred over values from the USGS Trace Metal 

Laboratory.

Four replicate pairs for gross alpha and gross beta 

radioactivity (72 hour and 30 day) were analyzed for 

variability. Acceptable precision for radiochemical 

constituents is defined as the presence of overlap between 

the results (value ±1-sigma CSU) for the two analyses where 

the range between the lower confidence limit of the activity 

measured in the groundwater sample and the upper confidence 

limit of the activity measured in the groundwater sample 

overlaps the range between the lower confidence limit of 

the activity measured in the replicate groundwater sample 

and the upper confidence limit of the activity measured in 

the replicate groundwater sample. Two replicate pairs for 

gross alpha radioactivity (72 hour), three pairs for gross 

alpha radioactivity (30 day), and all four pairs for gross beta 

radioactivity (72 hour and 30 day) yielded overlapping values 

and were, therefore, considered acceptable (table A4C). The 

gross alpha radioactivity (72 hour and 30 day) replicate pairs 

yielding non-overlapping values were all at activities less than 

the MCL-US of 15 pCi/L (tables 3J and 14); therefore, the less 

than acceptable precision at these low activities will not affect 

the assessments of groundwater quality being made by the 

GAMA Priority Basin Project.

Environmental detections were not modified on the basis 

of the replicate analysis.

Matrix-Spike Recoveries

Tables A5A–E presents a summary of matrix-spike 

recoveries for the SCRC. The addition of a spike or known 

concentration of a constituent to an 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. 

Seven environmental samples were spiked with 

VOCs to calculate matrix-spike recoveries. Median 

matrix-spike recoveries for all 85 VOC spike compounds 

were within the acceptable range of 70 to 130 percent 

(table A5A). One matrix-spike recover for two VOC spike 

compounds—perchloroethene (PCE, tetrachloroethene) 

and trichlorofluoromethane (CFC-11)—were greater than 

130 percent and both these VOCs also were detected in 

groundwater samples (tables 3A and 5). At least one matrixspike recover for four VOC spike compounds—bromomethane 

(methyl bromide), carbon disulfide, dichlorodifluoromethane 

(CFC-12), and styrene—were less than 70 percent. Of these 

VOC spike compounds, dichlorodifluoromethane (CFC-12) 

also was detected in groundwater samples (tables 3A, 5, and 

A5A). (Note: Low recoveries may indicate that the compound 

might be present at very low concentrations but not detected in 

some samples).

Six groundwater samples were spiked with pesticide 

and pesticide degradate compounds to calculate matrix-spike 

recoveries. Median matrix-spike recoveries for 43 of the 

63 spike compounds were within the acceptable range of 70 to 

130 percent (table A5B). The median matrix-spike recoveries 

for 10 of the 11 compounds detected in groundwater samples 

were within the acceptable range (tables 3B and 6A). 
Appendix 87

Median spike-matrix recovery for deethylatrazine (2-Chloro4-isopropylamino-6-amino-s-triazine) was less than the 

acceptable range (52 percent). At least one matrix spike 

recovery for three pesticide and pesticide degradate spike 

compounds was greater than 130 percent and one matrix-spike 

recovery was less than 70 percent, although none of these 

compounds were detected in any groundwater samples. At 

least one matrix-spike recovery for 45 pesticide and pesticide 

degradate spike compounds was less than 70 percent. Of 

these pesticide and pesticide degradate spike compounds, 

deethylatrazine, simazine, metolachlor, 3,4-Dichloroaniline, 

acetochlor, fipronil sulfide, fipronil sulfone, and prometon 

also were detected in groundwater samples (tables 3B, 6A, 

and A5B).

 Eight groundwater samples were spiked with polar 

pesticide and metabolite compounds to calculate matrixspike recoveries. Matrix-spike recoveries for 45 of the 

60 spike compounds were within the acceptable range of 70 

to 130 percent (table A5C). Median matrix-spike recoveries 

for three of the four compounds detected in groundwater 

samples were within the acceptable range. Median matrixspike recovery for 3-(4-chlorophenyl)-1-methyl urea was less 

than the acceptable range (58 percent) (tables 3C and 6B). 

Median matrix-spike recovery for nicosulfuron was greater 

than the acceptable range (188 percent), but nicosulfuron 

was not detected in any groundwater samples. At least one 

matrix-spike recovery for 3 polar pesticide and metabolite 

spike compounds was greater than 130 percent; at least one 

matrix-spike recovery for 6 spike compounds was greater 

than 130 percent and one matrix-spike recovery was less than 

70 percent; and at least one matrix-spike recovery for 41 spike 

compounds was less 70 percent. Of these polar pesticide and 

metabolite spike compounds, diuron, 3-(4-Chlorophenyl)-

1-methyl urea, bromacil, and fenuron also were detected in 

groundwater samples (tables 3C, 6B, and A5C). 

Four groundwater samples were spiked with perchlorate, 

two with NDMA, and six with 1,2,3-TCP to calculate matrixspike recoveries at Weck Laboratories, Inc. All median 

matrix-spike recoveries were within the acceptable range of 

70 to 130 percent (table A5D). One matrix-spike recovery 

for NDMA was less than 70 percent and was not detected in 

groundwater samples (tables 3E and A5D). 

Three groundwater samples were spiked with gross alpha 

and gross beta radiation to calculate matrix-spike recoveries. 

All matrix-spike recoveries were within the acceptable range 

of 70 to 130 percent (table A5E).

Environmental detections were not modified on the basis 

of the matrix-spike analysis.

Surrogate Compound Recoveries

Surrogate compounds were added to environmental 

samples in the laboratory and analyzed to evaluate the 

recovery of similar constituents. 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 

groundwater samples. Blank and environmental samples were 

considered separately to assess whether the matrixes present in 

groundwater samples affect surrogate recoveries. 

In SCRC, most surrogate recoveries were within the 

acceptable range of 70 to 130 percent. In total, 81 percent 

of the surrogate recoveries for VOC, 91 percent of the 

surrogate recoveries for pesticide and pesticide degradate, and 

73 percent of the surrogate recoveries for polar pesticide and 

metabolite analyses were within the acceptable range. 

Environmental detections were not modified on the basis 

of the surrogate recovery analysis.
88 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: 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 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. HPLC, high-performance liquid chromatography; USEPA, U.S. Environmental Protection Agency; UV, ultraviolet; VOCs, volatile organic compounds] Analyte Analytical Method Laboratory and analytical schedule Citation(s) Water-quality indicators Field parameters 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; Madsen and others, 2003; Sandstrom and others, 2001 Polar pesticides and metabolites Solid-phase extraction and HPLC/mass spectrometry with selective-ion monitoring NWQL, Schedule 2060 Furlong and others, 2001 Pharmaceuticals Solid-phase extraction and HPLC/mass spectrometry NWQL, Schedule 2080 Kolpin and others, 2002; Furlong and others, 2008 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

N-nitrosodimethylamine (NDMA) Isotopic dilution with gas chromatography

and chemical-ionization mass spectrometry(USEPA Method 1625 modified)

Weck Laboratories, Inc., standardoperating procedure ORG065.R10

U.S. Environmental Protection Agency, 1989;Plomley and others, 1994

1,2,3-TCP Isotopic dilution purge and trap/gas

chromatography/mass spectrometry 

Weck Laboratories, Inc., standardoperating procedure ORG083

Okamoto and others, 2002

Inorganic constituents

Nutrients Alkaline persulfate digestion, Kjedahl

digestion

NWQL, Schedule 2755 Fishman, 1993; Patton and Kryskalla, 2003

Nutrients Kjedahl digestion, colorimetry, photometry,

and gas diffusion.

NWQL, Schedule 2702 Fishman, 1993; U.S. Environmental 

Protection Agency, 1993; Patton and Truitt, 2000

Dissolved organic carbon (DOC) UV-promoted persulfate oxidation and infrared

spectrometry

NWQL, Laboratory Code 2612 Brenton and Arnett, 1993

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 contract laboratories.[Laboratory entity codes in the USGS National Water Information System (NWIS) for laboratories other than the USGS National Water-Quality Laboratory (NWQL) are given in parentheses after the laboratory names. HPLC, high-performance liquid chromatography; USEPA, U.S. Environmental Protection Agency; UV, ultraviolet; VOCs, volatile organic compounds]
Appendix 89

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 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. HPLC, high-performance liquid chromatography; USEPA, U.S. Environmental Protection Agency; UV, ultraviolet; VOCs, volatile organic compounds]

Analyte Analytical Method Laboratory and analytical schedule Citation(s)

Major and minor ions, trace elementsand nutrients

Atomic absorption spectrometry, colorimetry,ion-exchange chromatography, inductivelycoupled plasma atomic emission spectrometryand mass spectrometry

NWQL, Schedule 1948 Fishman and Friedman, 1989; Fishman, 1993;

Faires, 1993; McLain, 1993; Garbarino, 1999;Garbarino and Damrau, 2001; AmericanPublic Health Association, 1998; Garbarinoand others, 2006

Arsenic and iron speciation Various techniques of ultraviolet visible

(UV-VIS) spectrophotometry and atomicabsorbance spectroscopy

USGS Trace Metal Laboratory, Boulder,Colorado (USGSTMCO)

Stookey, 1970; To and others, 1998;McCleskey and others, 2003

Stable isotopes

Stable isotopes of hydrogen andoxygen in water

Gaseous hydrogen and carbon dioxide-waterequilibration and stable-isotope massspectrometry

USGS Stable Isotope Laboratory, Reston,Virginia (USGSSIVA), NWQL Schedule1142

Epstein and Mayeda, 1953; Coplen andothers, 1991; Coplen, 1994

Stable isotopes of nitrogen and oxygenin dissolved nitrate

Denitrifier method and mass spectrometry USGS Stable Isotope Laboratory, Reston,

Virginia (USGSSIVA), NWQLLaboratory Code 2900

Révész and Casciotti, 2007

Stable isotopes of sulfur in dissolvedsulfate

Vacuum extraction and mass spectrometry USGS Stable Isotope Laboratory, Reston,

Virginia (USGSSIVA), NWQLLaboratory Code 1951

Carmody and others, 1998

Stable isotopes of carbon in dissolvedinorganic carbon and carbon-14abundance

Accelerator mass spectrometry Woods Hole Oceanographic Institution,

National Ocean Sciences AcceleratorMass Spectrometry Facility (NOSAMS),NWQL Schedule 2255

Karlen and others, 1964; Olsson, 1970;Stuiver, 1980; Stuiver and Polach, 1977

Radioactivity and gases

Tritium Electrolytic enrichment-liquid scintillation USGS Stable Isotope and Tritium

Laboratory, Menlo Park, California(USGSH3CA)

Thatcher and others, 1977

Tritium and dissolved noble gases Helium-3 in-growth and mass spectrometry Lawrence Livermore National Laboratory

(CA-LLNL)

Moran and others, 2002; Eaton and others,2004

Dissolved gases (argon, carbondioxide, methane, nitrogen, andoxygen)

Gas chromatography/thermal conductivitydetector and flame ionization detector 

USGS Chlorofluorocarbon Laboratory(USGSCFCVA)

Busenberg and others, 2001

Gross alpha and gross betaradioactivity

Alpha and beta activity counting Eberline Analytical Services, NWQL

Schedule 1792

Kreiger and Whittaker, 1980 (USEPA method900.0)
90 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table A2. Preferred analytical schedules for constituents appearing on multiple schedules for samples collected for the South Coast 

Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.

[`Abbreviations: LLNL, Lawrence Livermore National Laboratory; SITL, U.S. Geological Survey Stable Isotope and Tritium Laboratory; TML, U.S. 

Geological Survey Trace Metal Laboratory, Boulder, Colorado; VOC, volatile organic compound; np, no preference]

Constituent Primary constituent 

classification

Analytical 

schedules

Preferred 

analytical 

schedule

Results from preferred method reported

Atrazine Pesticide 2003, 2060 2003

Caffeine Wastewater indicator 2060, 2080 2060

Deethylatrazine (2-Chloro-4-isopropylamino-6-amino-striazine)

Pesticide degradate 2003, 2060 2003

Tebuthiuron Pesticide 2003, 2060 2003

Results from both methods reported

1,2,3-TCP VOC Weck, 2020 Weck

Alkalinity Water-quality indicator field, 1948 field

Arsenic, total Trace element 1948, TML 1948

Iron, total Trace element 1948, TML 1948

Metalaxyl Fungicide 2003, 2060 np

pH Water-quality indicator field, 1948 field

Specific conductance Water-quality indicator field, 1948 field

Tritium Inorganic tracer LLNL, SITL np
Appendix 91

Constituent

Number of 

blank 

detections/ 

analyses

Concentrations 

detected 

in blanks

Number of 

groundwater 

samples 

V-coded or 

coded with ≤

Volatile organic compounds (VOC) (μg/L)

1,1-Dichloroethene (1,1-DCE) 1/14 E0.03 0

1,2,4-Trimethylbenzene 1/14 E0.08 18

Benzene 1/14 E0.02 0

Methyl ethyl ketone (2-butanone, MEK) 1/14 E0.83 0

Toluene 2/14 0.18, E0.03 2

Trace elements (μg/L)

Chromium 1/7 2.2 16

Copper 1/7 2.3 17

Lead 1/7 0.31 24

Nickel 1/7 0.25 3

Zinc 1/6 11.5 22

Nutrients and dissolved organic carbon (DOC) (mg/L)

Ammonia (as nitrogen) 1/5 E0.01 0

Total nitrogen (nitrate + nitrite + ammonia + organic-nitrogen) 1/5 0.12 0

Phosphate, orthophosphate (as phosphorus) 1/5 E0.004 0

DOC 1/3 E0.3 13

Major and minor ions (mg/L)

Chloride 1/7 0.48 0

Silica (as SiO2) 2/7 E0.013, E0.012 0

Table A3. Constituents detected in blanks collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring 

and Assessment (GAMA) study, California, May to December 2008.

[V-coded data are reported but not used in summary statistics. Abbreviations: E, estimated or having a higher degree of uncertainty; mg/L, milligrams per 

liter; μg/L, micrograms per liter; ≤, less than or equal to; V, analyte detected in sample and an associated blank; thus, data are not included in groundwater 

quality assessment]
92 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table A4A. Quality-control summary for replicate analyses of organic constituents detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—Continued 

[Abbreviations: SD, percent standard deviation; RSD, percent relative standassrd deviation; LRL, laboratory reporting limit; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; μg/L, micrograms per liter; mg/L, milligrams per liter; nv, no value in category]

Constituent

Number of 

nondetections/ 

number of 

replicates

Number of 

V-coded 

replicates

Number of SDs 

greater than 

10 percent/ 

number of 

replicates with 

concentration 

less than 5 times 

the LRL

Concentrations 

of replicates 

with SDs greater 

than 10 percent 

(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) (μg/L)

Chloroform (Trichloromethane) 8/8 nv nv nv nv nv

Perchloroethene (PCE, Tetrachloroethene) 7/8 nv 0/1 nv nv nvDichlorodifluoromethane (CFC-12) 7/8 nv 0/1 nv nv nvToluene 8/8 nv nv nv nv nvTrichlorofluoromethane (CFC-11) 7/8 nv 0/1 nv nv nv1,2,4-Trimethylbenzene 4/8 4 nv nv nv nv1,1-Dichloroethene (1,1-DCE) 8/8 nv nv nv nv nv1,2-Dichloropropane 8/8 nv nv nv nv nvcis-1,2-Dichloroethene (cis-1,2-DCE) 8/8 nv nv nv nv nvMethylene chloride (Dichloromethane) 8/8 nv nv nv nv nvMethyl tert-butyl ether (MTBE) 8/8 nv nv nv nv nvTetrahydrofuran 8/8 nv nv nv nv nvtrans-1,2-Dichloroethene (trans-1,2-DCE) 8/8 nv nv nv nv nvTrichloroethene (TCE) 8/8 nv nv nv nv nvVinyl chloride (Chloroethene) 8/8 nv nv nv nv nv

Pesticides and pesticide degradates (Schedule 2003) (μg/L)

Deethylatrazine (2-Chloro-4-isopropylamino-6-amino-s-triazine) 8/8 nv nv nv nv nvAtrazine 8/8 nv nv nv nv nvSimazine 8/8 nv nv nv nv nvMetolachlor 8/8 nv nv nv nv nvMetalaxyl 8/8 nv nv nv nv nv3,4-Dichloroaniline 8/8 nv nv nv nv nv

Acetochlor 8/8 nv nv nv nv nv

Table A4A. Quality-control summary for replicate analyses of organic constituents detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008. [Abbreviations: SD, percent standard deviation; RSD, percent relative standard deviation; LRL, laboratory reporting limit; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; μg/L, micrograms per liter; mg/L, milligrams per liter; nv, no value in category]
Appendix 93

Table A4A. Quality-control summary for replicate analyses of organic constituents detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—Continued [Abbreviations: SD, percent standard deviation; RSD, percent relative standassrd deviation; LRL, laboratory reporting limit; V, analyte detected in sample and associated blank; thus, data are not included in groundwater quality assessment; μg/L, micrograms per liter; mg/L, milligrams per liter; nv, no value in category]

Constituent

Number of 

nondetections/ 

number of 

replicates

Number of 

V-coded 

replicates

Number of SDs 

greater than 

10 percent/ 

number of 

replicates with 

concentration 

less than 5 times 

the LRL

Concentrations 

of replicates 

with SDs greater 

than 10 percent 

(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) 

Fipronil sulfide 8/8 nv nv nv nv nv

Fipronil sulfone 8/8 nv nv nv nv nvPrometon 8/8 nv nv nv nv nvDacthal (DCPA) 8/8 nv nv nv nv nv

Polar pesticides and metabolites (Schedule 2060) (μg/L)

Diuron 8/8 nv nv nv nv nv3-(4-Chlorophenyl)-1-methyl urea 8/8 nv nv nv nv nvBromacil 8/8 nv nv nv nv nvFenuron 8/8 nv nv nv nv nv

Constituent of special interest (μg/L)

Perchlorate 2/7 nv 0/2 nv 0/3 nv

Dissolved organic carbon (DOC) (mg/L)

DOC 1/5 2 nv nv 0/2 nv
94 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table A4B. Quality-control summary for replicate analyses of inorganic constituents, isotope tracers, and radioactivity detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—Continued

[Abbreviations: SD, percent standard deviation; RSD, percent relative standard deviation in percent; LRL, laboratory reporting limit; MDL, method detection limit; MRL, minimum reporting level; μg/L, micrograms per liter; mg/L, milligrams per liter; SiO2, silicon dioxide; H, hydrogen; O, oxygen; N, nitrogen; C, carbon; pCi/L, picocuries per liter; ≤, less than or equal to; nv, no value in category]

Constituent

Number of 

non-detect 

or ≤-coded 

replicates/number

of replicates 

Number of SDs 

greater than 

10 percent/ number 

of replicates with 

concentration 

less than 5 times 

the LRL/MDL/MRL

Concentrations 

of replicates 

with SDs greater 

than 10 percent 

(environmental, 

replicate) 

Number of RSDs 

greater than 

10 percent/ number 

of replicates with 

concentration 

greater than 

5 times the 

LRL/MDL/MRL

Concentrations of 

replicates with 

RSDs greater

 than 10 percent 

(environmental, 

replicate) 

Trace Elements (μg/L)

Aluminum 5/5 nv nv nv nv

Antimony 4/5 0/1 nv nv nv

Arsenic 0/5 nv nv 0/5 nv

Barium 0/5 nv nv 0/5 nv

Beryllium 4/5 0/1 nv nv nv

Boron 0/5 nv nv 1/5 (383, 502)

Cadmium 0/5 0/4 nv 0/1 nv

Chromium 2/5 0/1 nv 0/2 nv

Cobalt 0/5 0/5 nv nv nv

Copper 5/5 nv nv nv nv

Iron 3/5 nv nv 0/2 nv

Lead 5/5 nv nv nv nv

Lithium 0/5 nv nv 0/5 nv

Manganese 1/5 0/2 nv 0/2 nv

Mercury 5/5 nv nv nv nv

Molybdenum 0/5 nv nv 0/5 nv

Nickel 1/5 0/2 nv 0/2 nv

Selenium 0/5 0/2 nv 0/3 nv

Silver 5/5 nv nv nv nv

Strontium 0/5 nv nv 0/5 nv

Thallium 5/5 nv nv nv nv

Tungsten 5/5 nv nv nv nv

Uranium 0/5 nv nv 0/5 nv

Vanadium 0/5 0/1 nv 0/4 nv

Zinc 4/5 0/1 nv nv nv

Table A4B. Quality-control summary for replicate analyses of inorganic constituents, isotope tracers, and radioactivity detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.[Abbreviations: SD, percent standard deviation; RSD, percent relative standard deviation in percent; LRL, laboratory reporting limit; MDL, method detection limit; MRL, minimum reporting level; μg/L, micrograms per liter; mg/L, milligrams per liter; SiO2, silicon dioxide; H, hydrogen; O, oxygen; N, nitrogen; C, carbon; pCi/L, picocuries per liter; ≤, less than or equal to; nv, no value in category]
Appendix 95

Table A4B. Quality-control summary for replicate analyses of inorganic constituents, isotope tracers, and radioactivity detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—Continued[Abbreviations: SD, percent standard deviation; RSD, percent relative standard deviation in percent; LRL, laboratory reporting limit; MDL, method detection limit; MRL, minimum reporting level; μg/L, micrograms per liter; mg/L, milligrams per liter; SiO2, silicon dioxide; H, hydrogen; O, oxygen; N, nitrogen; C, carbon; pCi/L, picocuries per liter; ≤, less than or equal to; nv, no value in category]

Constituent

Number of 

non-detect 

or ≤-coded 

replicates/number

of replicates 

Number of SDs 

greater than 

10 percent/ number 

of replicates with 

concentration 

less than 5 times 

the LRL/MDL/MRL

Concentrations 

of replicates 

with SDs greater 

than 10 percent 

(environmental, 

replicate) 

Number of RSDs 

greater than 

10 percent/ number 

of replicates with 

concentration 

greater than 

5 times the 

LRL/MDL/MRL

Concentrations of 

replicates with 

RSDs greater

 than 10 percent 

(environmental, 

replicate) 

Nutrients (mg/L)

Ammonia, as nitrogen 3/6 0/2 nv 0/1 nv

Ammonia, plus organic nitrogen 

(unfiltered)

0/1 0/1 nv nv nv

Ammonia, plus organic nitrogen (filtered) 0/1 0/1 nv nv nv

Nitrite, as nitrogen 4/6 0/1 nv 0/1 nv

Nitrite plus nitrate, as nitrogen 2/6 nv nv 0/4 nv

Total nitrogen (nitrate + nitrite + ammonia 

+ organic-nitrogen) as nitrogen

0/5 nv nv 0/5 nv

Phosphorus, as phosphorus (filtered) 0/1 0/1 nv nv nv

Phosphate, orthophosphate (as phosphorus) 0/6 0/1 nv 0/5 nv

Phosphorus, as phosphorus (unfiltered) 0/1 0/1 nv nv nv

Major and minor ions, silica, total dissolved soilds (TDS), and alkalinity (mg/L)

Bromide 0/5 nv nv 0/5 nv

Calcium 0/6 nv nv 0/6 nv

Chloride 0/6 nv nv 0/6 nv

Fluoride 0/6 0/6 nv nv nv

Iodide 2/5 0/2 nv 0/1 nv

Magnesium 0/6 nv nv 0/6 nv

Potassium 0/6 nv nv 0/6 nv

Silica (as SiO2) 0/6 nv nv 0/6 nv

Sodium 0/6 nv nv 0/6 nv

Sulfate 0/6 nv nv 0/6 nv

TDS 0/6 nv nv 0/6 nv

Laboratory alkalinity 0/5 nv nv 0/5 nv
96 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program Table A4B. Quality-control summary for replicate analyses of inorganic constituents, isotope tracers, and radioactivity detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—Continued

[Abbreviations: SD, percent standard deviation; RSD, percent relative standard deviation in percent; LRL, laboratory reporting limit; MDL, method detection limit; MRL, minimum reporting level; μg/L, micrograms per liter; mg/L, milligrams per liter; SiO2, silicon dioxide; H, hydrogen; O, oxygen; N, nitrogen; C, carbon; pCi/L, picocuries per liter; ≤, less than or equal to; nv, no value in category]

Constituent

Number of 

non-detect 

or ≤-coded 

replicates/number

of replicates 

Number of SDs 

greater than 

10 percent/ number 

of replicates with 

concentration 

less than 5 times 

the LRL/MDL/MRL

Concentrations 

of replicates 

with SDs greater 

than 10 percent 

(environmental, 

replicate) 

Number of RSDs 

greater than 

10 percent/ number 

of replicates with 

concentration 

greater than 

5 times the 

LRL/MDL/MRL

Concentrations of 

replicates with 

RSDs greater

 than 10 percent 

(environmental, 

replicate) 

Arsenic and iron species (μg/L)

Arsenic, total 1/5 0/2 nv 0/2 nv

Arsenic (III) 3/5 0/1 nv 0/1 nv

Iron, total 0/5 0/2 nv 1/3 (8, 11)

Iron (II) 2/5 0/1 nv 0/2 nv

Isotope tracers and radioactivity (units, as noted)

δ2H in water (per mil) 0/9 nv nv 0/9 nv

δ18O in water (per mil) 0/9 nv nv 0/9 nv

δ13C in dissolved inorganic carbon (per mil) 0/5 nv nv 0/5 nv

δ15N in dissolved nitrate (per mil) 0/3 nv nv 0/3 nv

δ18O in dissolved nitrate (per mil) 0/3 nv nv 0/3 nv

Tritium (pCi/L) 1/8 0/4 nv 0/3 nv

Carbon-14 (percent modern) 0/5 nv nv 0/5 nv
Appendix 97

Table A4C. Quality-control summary for replicate analyses of gross alpha and gross beta radioactivity 

detected in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring 

and Assessment (GAMA) study, California, May to December 2008.

[Abbreviations: CSU, 1-sigma combined standard uncertainty; ±, plus or minus; pCi/L, picocuries per liter; —, not detected; nv, 

no value in category]

Constituent

Number of 

non-overlapping 

values/ number 

of replicates

Activites for replicates 

with non-overlapping values 

(environmental ± CSU, replicate ± CSU) 

(pCi/L)

Gross alpha radioactivity, 72 hour count 2/4 (4.83 ± 0.9, 2.55 ± 0.66)(—, 4.2 ± 1.3)

Gross alpha radioactivity, 30 day count 1/4 (1.18 ± 0.81, 3.3 ± 1.2)

Gross beta radioactivity, 72 hour count 0/4 nv

Gross beta radioactivity, 30 day count 0/4 nv
98 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table A5A. Quality-control summary for matrix-spike recoveries of volatile organic compounds (VOC) in samples collected for the 

South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 

2008.—Continued

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number of 

spike 

samples

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Acetone 7 73 117 94

Acrylonitrile 7 93 166 112

tert-Amyl methyl ether (TAME) 7 92 125 105

Benzene 7 97 113 107

Bromobenzene 7 94 116 99

Bromochloromethane 7 97 123 114

Bromodichloromethane 7 87 119 107

Bromoform (Tribromomethane) 7 84 118 103

Bromomethane (Methyl bromide) 7 94 105 99

n-Butylbenzene 7 86 112 95

sec-Butylbenzene 7 95 118 104

tert-Butylbenzene 7 97 121 105

Carbon disulfide 7 68 94 81

Carbon tetrachloride (Tetrachloromethane) 7 92 127 107

Chlorobenzene 7 95 121 104

Chloroethane 7 81 114 101

Chloroform (Trichloromethane) 1 7 95 125 115

Chloromethane 7 86 108 102

3-Chloropropene 7 106 126 112

2-Chlorotoluene 7 98 116 102

4-Chlorotoluene 7 94 117 101

Dibromochloromethane 7 87 116 107

1,2-Dibromo-3-chloropropane (DBCP) 7 89 127 100

1,2-Dibromoethane (EDB) 7 93 114 108

Dibromomethane 7 89 118 101

1,2-Dichlorobenzene 7 92 124 109

1,3-Dichlorobenzene 7 91 124 107

1,4-Dichlorobenzene 7 92 121 103

trans-1,4-Dichloro-2-butene 7 89 119 99

Dichlorodifluoromethane (CFC-12) 1 7 51 93 72

1,1-Dichloroethane (1,1-DCA) 7 95 122 114

1,2-Dichloroethane (1,2-DCA) 7 90 122 103

1,1-Dichloroethene (1,1-DCE) 1 7 89 107 96

cis-1,2-Dichloroethene (cis-1,2-DCE) 1 7 100 125 107

trans-1,2-Dichloroethene (trans-1,2-DCE) 1 7 104 122 116

1,2-Dichloropropane 1 7 96 119 105

1,3-Dichloropropane 7 96 119 110

2,2-Dichloropropane 7 87 106 94

1,1-Dichloropropene 7 91 111 98

cis-1,3-Dichloropropene 7 85 111 92

trans-1,3-Dichloropropene 7 84 111 95

Diethyl ether 7 96 126 109

Diisopropyl ether (DIPE) 7 94 120 100

Table A5A. Quality-control summary for matrix-spike recoveries of volatile organic compounds (VOC) in samples collected for the 

South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 

2008.

[Acceptable recovery range is between 70 and 130 percent]
Appendix 99

Table A5A. Quality-control summary for matrix-spike recoveries of volatile organic compounds (VOC) in samples collected for the 

South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 

2008.—Continued

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number of 

spike 

samples

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Ethylbenzene 7 92 122 101

Ethyl tert-butyl ether (ETBE) 7 89 130 101

Ethyl methacrylate 7 91 118 97

o-Ethyl toluene (1-Ethyl-2-methyl benzene) 7 87 116 99

Hexachlorobutadiene 7 74 108 79

Hexachloroethane 7 87 119 105

2-Hexanone (n-Butyl methyl ketone) 7 90 112 100

Iodomethane (Methyl iodide) 7 92 123 115

Isopropylbenzene 7 84 122 98

4-Isopropyl-1-methyl benzene 7 92 113 104

Methyl acrylate 7 95 123 110

Methyl acrylonitrile 7 99 124 114

Methyl tert-butyl ether (MTBE) 1 7 93 122 104

Methyl iso-butyl ketone (MIBK) 7 88 113 97

Methylene chloride (Dichloromethane) 1 7 78 111 109

Methyl ethyl ketone (2-butanone, MEK) 7 85 117 99

Methyl methacrylate 7 85 121 94

Naphthalene 7 86 116 103

Perchloroethene (PCE, Tetrachloroethene) 1 7 96 140 103

n-Propylbenzene 7 86 116 98

Styrene 7 4 119 104

1,1,1,2-Tetrachloroethane 7 89 126 109

1,1,2,2-Tetrachloroethane 7 93 130 113

Tetrahydrofuran 1 7 85 116 108

1,2,3,4-Tetramethylbenzene 7 86 114 103

1,2,3,5-Tetramethylbenzene 7 96 126 112

Toluene 1 7 98 115 103

1,2,3-Trichlorobenzene 7 88 123 108

1,2,4-Trichlorobenzene 7 83 106 100

1,1,1-Trichloroethane (1,1,1-TCA) 7 91 123 106

1,1,2-Trichloroethane (1,1,2-TCA) 7 88 118 111

Trichloroethene (TCE) 1 7 93 112 99

Trichlorofluoromethane (CFC-11) 1 7 75 148 99

1,2,3-TCP 7 85 124 106

Trichlorotrifluoroethane (CFC-113) 7 72 120 86

1,2,3-Trimethylbenzene 7 100 127 108

1,2,4-Trimethylbenzene 7 89 115 104

1,3,5-Trimethylbenzene 7 88 115 103

Vinyl bromide (Bromoethene) 7 58 129 109

Vinyl chloride (Chloroethene) 1 7 91 126 109

m- and p-Xylene 7 97 120 106

o-Xylene 7 87 126 99

1

 Constituents detected in groundwater samples.
100 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: 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 

South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 

2008.—Continued

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number 

of spike 

samples

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Acetochlor 1 6 70 109 92

Alachlor 6 74 117 97

Atrazine 1 6 82 105 93

Azinphos-methyl 6 38 125 85

Azinphos-methyl oxon 6 13 96 81

Benfluralin 6 47 79 59

Carbaryl 6 49 169 108

2-Chloro-2,6-diethylacetanilide 6 72 113 95

4-Chloro-2-methylphenol 6 43 84 67

Chlorpyrifos 6 52 94 83

Chlorpyrifos oxon 6 12 89 25

Cyfluthrin 6 39 80 54

Cypermethrin 6 35 71 45

Dacthal (DCPA) 1 6 97 116 105

Deethylatrazine (2-Chloro-4-isopropylamino-6-amino-s-triazine) 1 6 21 86 52

Desulfinylfipronil 6 87 109 98

Desulfinylfipronil amide 6 47 142 102

Diazinon 6 71 100 88

3,4-Dichloroaniline 1 6 57 94 81

Dichlorvos 6 8 46 19

Dicrotophos 6 8 106 87

Dieldrin 6 81 106 87

2,6-Diethylaniline 6 75 98 87

Dimethoate 6 17 66 35

Ethion 6 56 91 69

Ethion monoxon 6 63 109 81

2-Ethyl-6-methylaniline 6 75 99 84

Fenamiphos 6 63 113 89

Fenamiphos sulfone 6 67 120 79

Fenamiphos sulfoxide 6 16 48 21

Fipronil 6 63 117 91

Fipronil sulfide 1 6 60 114 94

Fipronil sulfone 1 6 62 95 73

Fonofos 6 70 93 88

Hexazinone 6 40 90 58

Iprodione 6 37 104 67

Isofenphos 6 60 121 94

Malaoxon 6 42 121 86

Malathion 6 55 103 94

Metalaxyl 1 6 74 113 92

Methidathion 6 75 115 88

Metolachlor 1 6 69 106 94

Table A5B. Quality-control summary for matrix-spike recoveries of pesticides and pesticide degradates in samples collected for the 

South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 

2008. 

[Acceptable recovery range is between 70 and 130 percent]
Appendix 101

Table A5B. Quality-control summary for matrix-spike recoveries of pesticides and pesticide degradates in samples collected for the 

South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 

2008.—Continued

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number 

of spike 

samples

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Metribuzin 6 57 111 74

Myclobutanil 6 68 100 83

1-Naphthol 6 13 61 31

Paraoxon-methyl 6 25 71 63

Parathion-methyl 6 55 100 80

Pendimethalin 6 66 117 94

cis-Permethrin 6 31 74 42

Phorate 6 37 75 62

Phorate oxon 6 71 122 87

Phosmet 6 10 23 20

Phosmet oxon 6 3 56 21

Prometon 1 6 69 108 86

Prometryn 6 75 113 95

Pronamide (Propyzamide) 6 61 109 91

Simazine 1 6 66 110 85

Tebuthiuron 6 57 161 106

Terbufos 6 52 92 74

Terbufos oxon sulfone 6 42 119 95

Terbuthylazine 6 86 113 98

Tribufos 6 40 84 57

Trifluralin 6 54 89 71

1

 Constituents detected in groundwater samples.
102 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table A5C. Quality-control summary for matrix-spike recoveries of polar pesticides and metabolites in samples collected for the South 

Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—

Continued

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number of 

spike

samples

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Acifluorfen 8 24 52 43

Aldicarb 8 18 78 50

Aldicarb sulfone 8 15 82 47

Aldicarb sulfoxide 8 40 110 89

Atrazine 8 51 111 93

Bendiocarb 8 55 93 85

Benomyl 8 38 101 65

Bensulfuron-methyl 8 109 152 116

Bentazon 8 53 91 77

Bromacil 1 8 42 101 77

Bromoxynil 8 38 84 60

Caffeine 8 55 89 73

Carbaryl 8 46 98 88

Carbofuran 8 67 107 94

Chloramben, methyl ester 8 67 101 87

Chlorimuron-ethyl 8 58 152 120

3-(4-Chlorophenyl)-1-methyl urea 1 8 31 96 58

Clopyralid 7 32 84 44

Cycloate 8 59 76 70

2,4-D 8 59 84 75

2,4-D methyl ester 1 7

2,4-D plus 2,4-D methyl ester 8 59 85 75

2,4-DB (4-(2,4-Dichlorophenoxy)butyric acid) 8 44 78 54

DCPA (Dacthal) monoacid 8 53 85 78

Deethylatrazine (2-Chloro-4-isopropylamino-6-amino-s-triazine) 8 32 79 66

Deisopropyl atrazine (2-Chloro-6-ethylamino-4-amino-s-triazine) 8 46 89 74

Dicamba 8 42 73 60

Dichlorprop 8 65 100 82

Dinoseb (Dinitrobutyl phenol) 8 34 102 67

Diphenamid 8 78 113 96

Diuron 1 8 58 110 94

Fenuron 1 8 42 133 100

Flumetsulam 8 55 140 116

Fluometuron 8 55 106 90

Hydroxyatrazine (2-Hydroxy-4-isopropylamino-6-ethylamino-s-triazine) 8 36 118 106

3-Hydroxycarbofuran 8 34 109 81

Imazaquin 8 62 174 106

Imazethapyr 8 21 141 93

Imidacloprid 8 48 103 100

Linuron 8 69 99 89

MCPA (2-Methyl-4-chlorophenoxyacetic acid) 8 65 96 78

MCPB (4-(2-Methyl-4-chlorophenoxy)butyric acid) 8 40 69 50

Metalaxyl 8 77 107 97

Table A5C. Quality-control summary for matrix-spike recoveries of polar pesticides and metabolites in samples collected for the South 

Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.

[Acceptable recovery range is between 70 and 130 percent]
Appendix 103

Table A5C. Quality-control summary for matrix-spike recoveries of polar pesticides and metabolites in samples collected for the South 

Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.—

Continued

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number of 

spike

samples

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Methiocarb 8 70 100 85

Methomyl 8 73 120 97

Metsulfuron methyl 8 13 149 93

Neburon 8 69 93 83

Nicosulfuron 8 155 343 188

Norflurazon 8 78 107 97

Oryzalin 8 60 83 73

Oxamyl 8 67 100 88

Picloram 7 35 89 59

Propham 8 63 94 83

Propiconazole 8 72 91 80

Propoxur 8 73 111 94

Siduron 8 81 123 106

Sulfometuron-methyl 8 80 151 119

Tebuthiuron 8 54 129 94

Terbacil 8 51 95 76

Triclopyr 8 62 90 76

1

 Constituents detected in groundwater samples.
104 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

Table A5D. Quality-control summary for matrix-spike recoveries of constituents of special interest in samples collected for the South 

Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008.

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number of 

spike 

samples

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Perchlorate 1 4 88 106 100

N-nitrosodimethylamine (NDMA) 2 63 86 75

1,2,3-TCP 6 81 117 101

1

 Constituents detected in groundwater samples.

Table A5E. Quality-control summary for matrix-spike recoveries of gross alpha and gross beta radioactivity in samples collected for 

the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 

2008.

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number of 

spike 

samples

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Gross alpha radioactivity, 72-hour count 1 3 83 96 90

Gross alpha radioactivity, 30-day count 1 3 94 112 96

Gross beta radioactivity, 72-hour count 1 3 80 97 92

Gross beta radioactivity, 30-day count 1 3 86 93 91

1

 Constituents detected in groundwater samples.
Appendix 105

Table A6. Quality-control summary for surrogate recoveries of volatile organic compounds (VOC), pesticides and pesticide degradates, and polar pesticides and metabolites in samples collected for the South Coast Range–Coastal (SCRC) Groundwater Ambient Monitoring and Assessment (GAMA) study, California, May to December 2008. [VOC, volatile organic compound]

Surrogate Analytical schedule Constitutent or constituent class analyzed Number of blanks analyses Median recovery in blanks (percent)

Number of 

surrogate 

recoveries 

below 

70 percent 

in blanks

Number of 

surrogate 

recoveries 

above 

130 percent 

in blanks

Number 

of sample 

analyses

Median 

recovery 

in samples 

(percent)

Number of 

surrogate 

recoveries 

below 

70 percent 

in samples

Number of 

surrogate 

recoveries 

above 

130 percent

 in samples

1-Bromo-4-fluorobenzene 2020 VOC 14 80 0 0 70 81 1 01,2-Dichloroethane-d4 2020 VOC 14 118 0 2 70 131 0 38Toluene-d8 2020 VOC 14 94 0 0 70 95 0 0Diazinon-d10 2003 Pesticide 7 75 2 0 69 88 12 0α-HCH-d6 2003 Pesticide 7 85 0 0 69 91 0 02,4,5-T (2,4,5-trichlorophenoxyacetic 

acid)

2060 Polar pesticide 7 87 0 0 69 78 16 0

Barban 2060 Polar pesticide 7 84 0 0 69 80 8 1Caffeine-13C 2060 Polar pesticide 7 86 1 0 69 73 30 0
106 Groundwater-Quality Data in the South Coast Range–Coastal Study Unit, 2008: Results from the California GAMA Program

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Mathany and others—Groundwater Quality Data in the South Coast Range-Coastal Study Unit, 2008: Results from the California GAMA Program—Data Series 504

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