U.S. Department of the Interior

U.S. Geological Survey

Data Series 404

Prepared in cooperation with the California State Water Resources Control Board

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

Ground-Water Quality Data in the Upper Santa Ana

Watershed Study Unit, November 2006-March 2007:

Results from the California GAMA Program
Cover:

Upper photo: Urban development overlooking the Santa Ana River near Yorba Linda. 

(Photo credit: Phil Contreras, U.S. Geological Survey, 1998)

Lower photo: Production well in Riverside County (Photo credit: Mike Judd, U.S. 

Geological Survey, 2007)
Ground-Water Quality Data in the 

Upper Santa Ana Watershed Study Unit, 

November 2006–March 2007: Results from 

the California GAMA Program

By Robert Kent and Kenneth Belitz

Prepared in cooperation with the California State Water Resources Control Board

Data Series 404

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

U.S. Geological Survey, Reston, Virginia: 2009

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Suggested citation:

Kent, Robert, 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. Available at http://pubs.usgs.gov/ds/404
iii

Contents

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

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

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

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

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

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

Sample Collection and Analysis.........................................................................................................9

Data Reporting.....................................................................................................................................10

Quality Assurance ..............................................................................................................................10

Water-Quality Results ................................................................................................................................10

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

Comparison Thresholds.....................................................................................................................11

Ground-Water-Quality Data ..............................................................................................................12

Water-Quality Indicators ..........................................................................................................12

Organic Constituents.................................................................................................................12

Constituents of Special Interest..............................................................................................13

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

Isotopic Tracer Constituents....................................................................................................15

Dissolved Standard and Noble Gases....................................................................................15

Radioactive Constituents..........................................................................................................15

Microbial Indicators..................................................................................................................16

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

Summary .......................................................................................................................................................16

Acknowledgments.......................................................................................................................................17

References Cited..........................................................................................................................................17

Appendix .......................................................................................................................................................89
iv

Figures

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

Upper Santa Ana Watershed Groundwater Ambient Monitoring and

Assessment (GAMA) study unit, California ............................................. 3

Figure 2. Map showing the California Department of Water Resources defined

ground-water basins and major hydrologic features in the Upper Santa Ana

Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study

unit, California .............................................................................. 5

Figure 3. Map showing the California Department of Water Resources defined

ground-water subbasins of the Upper Santa Ana Valley ground-water basin

in the Upper Santa Ana Watershed Groundwater Ambient Monitoring and

Assessment (GAMA) study unit, California ............................................. 6

Figure 4. Map showing the distribution of study unit grid cells and the location of

sampled grid wells and understanding wells in the Upper Santa Ana

Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study

unit, California .............................................................................. 8

Tables

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

the Upper Santa Ana Watershed Groundwater Ambient Monitoring and 

Assessment (GAMA) study, California, November 2006 to March 2007............... 23

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

collected for the slow, intermediate, fast, and topical well sampling schedules 

in the Upper Santa Ana Watershed Groundwater Ambient Monitoring and 

Assessment (GAMA) study, California, November 2006 to March 2007............... 25

Table 3A. Volatile organic compounds, primary uses or sources, comparative thresholds, 

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

Laboratory schedule 2020 .................................................................. 26

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

thresholds, and reporting information for the U.S. Geological Survey National 

Water Quality Laboratory schedule 2033 ................................................ 28

Table 3C. Polar pesticides and pesticide degradates, primary uses or sources, 

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

Survey National Water Quality Laboratory schedule 2060 ........................... 30

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

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

Laboratory schedule 2080 .................................................................. 32

Table 3E. Wastewater-indicator compounds, primary uses or sources, comparative 

thresholds, and reporting information for the U.S. Geological Survey National 

Water Quality Laboratory schedule 4433 ................................................ 33

Table 3F. Constituents of special interest, primary uses or sources, comparative 

thresholds, and reporting information for the Montgomery Watson-Harza 

Laboratory .................................................................................... 35

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

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

Laboratory schedule 2755 and lab code 2612 .......................................... 35
v

Tables—Continued

Table 3H. Major and minor ions, silica, total dissolved solids, and trace elements, 

comparative thresholds, and reporting information for the USGS National 

Water Quality Laboratory schedule 1948 ................................................ 36

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

information for the U.S. Geological Survey Trace Metal Laboratory, Boulder, 

Colorado .................................................................................... 37

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

information for laboratories ............................................................... 38

Table 3K. Dissolved and noble gases, comparative thresholds, and reporting information 

for dissolved gases analyzed by the U.S. Geological Survey Chlorofluorocarbon 

Laboratory (CFC) and the Lawrence Livermore National Laboratory (LLNL) ......... 39

Table 3L. Microbial constituents, comparison thresholds, and reporting information for 

the U.S. Geological Survey Ohio Microbiology Laboratory parameter codes 

90901, 90900, 99335 and 99332 ............................................................ 39

Table 4. Water-quality indicators in samples collected for the Upper Santa Ana 

Watershed Groundwater Ambient Monitoring and Assessment (GAMA) 

study, California, November 2006 to March 2007 ....................................... 40

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

Upper Santa Ana Watershed Groundwater Ambient Monitoring and 

Assessment (GAMA) study, California, November 2006 to March 2007............... 44

Table 6. Pesticides and pesticide degradates detected in samples analyzed using 

schedules 2033 and 2060 collected for the Upper Santa Ana Watershed 

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

November 2006 to March 2007 ............................................................ 54

Table 7. Pharmaceutical compounds detected in samples collected for the Upper 

Santa Ana Watershed Groundwater Ambient Monitoring and Assessment 

(GAMA) study, California, November 2006 to March 2007.............................. 62

Table 8. Constituents of special interest (perchlorate, N-Nitrosodimethylamine [NDMA], 

and 1,2,3-trichloropropane [1,2,3-TCP], and 1,4-dioxane) detected in samples 

collected in the Upper Santa Ana Watershed Groundwater Ambient Monitoring 

and Assessment (GAMA) study, California, November 2006 to March 2007 ......... 63

Table 9. Nutrients and dissolved organic carbon detected in samples collected for 

the Upper Santa Ana Watershed Ground-Water Ambient Monitoring and 

Assessment (GAMA) Program, California, November 2006–February 2007 ......... 66

Table 10. Major and minor ions, silica, and total dissolved solids detected in samples 

collected for the Upper Santa Ana Watershed Groundwater Ambient 

Monitoring and Assessment (GAMA) study, California, November 2006 to 

March 2007 ................................................................................. 69

Table 11. Trace elements detected in ground-water samples collected for the Upper 

Santa Ana Watershed Groundwater Ambient Monitoring and Assessment 

(GAMA) study, California, November 2006 to March 2007.............................. 72

Table 12. Species of inorganic arsenic, iron, and chromium detected in samples 

collected for the Upper Santa Ana Watershed Ground-Water Ambient 

Monitoring and Assessment (GAMA) Program, California, 

November 2006–February 2007 ............................................................ 78
vi

Tables—Continued

Appendix Tables

Table 13. Results for analyses of stable isotope ratios, carbon-14, and tritium activities 

in samples collected for the Upper Santa Ana Watershed Ground-Water 

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

November 2006–February 2007 ............................................................ 79

Table 14. Dissolved gases detected in ground-water samples collected for the Upper 

Santa Ana Watershed Ground-Water Ambient Monitoring and Assessment 

(GAMA) Program, California, November 2006–February 2007 ........................ 82

Table 15. Results for analyses of noble gases detected in samples collected for the 

Upper Santa Ana Watershed Groundwater Ambient Monitoring and 

Assessment (GAMA) study, California, November 2006 to March 2007............... 84

Table 16. Radioactive constituents in ground-water samples collected for the Upper 

Santa Ana Watershed Ground-Water Ambient Monitoring and Assessment 

(GAMA) Program, California, November 2006–February 2007 ........................ 87

Table 17. Microbial indicators detected in samples collected for the Upper Santa Ana 

Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, 

California, November 2006 to March 2007 ................................................ 88

Table A1. Methods used to measure organic, inorganic, and microbial constituents 

analyzed by the U.S. Geological Survey (USGS) National Water Quality 

Laboratory (NWQL) and contract laboratories .......................................... 98

Table A2. Analytical schedules for constituents appearing on multiple schedules 

used to analyze samples collected for the Upper Santa Ana Watershed 

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

November 2006 to March 2007 ............................................................100

Table A3. Constituents detected in field blanks collected for the Upper Santa Ana 

Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, 

California, November 2006 to March 2007 ................................................101

Table A4A. Quality-control summary of replicate analyses of organic and inorganic 

compounds detected in samples collected for the Upper Santa Ana Watershed 

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

November 2006 to March 2008 ............................................................102

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

interest, stable isotopes, dissolved gases, noble gases, and radioactive 

constituents detected in samples collected for the Upper Santa Ana Watershed 

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

November 2006 to March 2008 ............................................................103

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

compounds (VOCs) in samples collected for the Upper Santa Ana Watershed 

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

November 2006 to March 2007 ............................................................104

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

pesticide degradates (lab analytical schedule 2060) in samples collected for 

the Upper Santa Ana Watershed Groundwater Ambient Monitoring and 

Assessment (GAMA) study, California, November 2006 to March 2007...............106
vii

Appendix Tables—Continued

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

degradates (lab analytical schedule 2033) in samples collected for the Upper 

Santa Ana Watershed Groundwater Ambient Monitoring and Assessment 

(GAMA) study, California, November 2006 to March 2007..............................108

Table A5D. Quality-control summary of matrix-spike recoveries of pharmaceutical 

compounds in samples collected for the Upper Santa Ana Watershed 

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

November 2006 to March 2007 ............................................................110

Table A5E. Quality-control summary of matrix-spike recoveries of wastewater indicator 

compounds in samples collected for the Upper Santa Ana Watershed 

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

November 2006 to March 2007 ............................................................111

Table A5F. Quality-control summary of matrix-spike recoveries of 1,4-Dioxane, 

1,2,3-Trichloropropane, and N-Nitrosodimethylamine in samples collected for 

the Upper Santa Ana Watershed Groundwater Ambient Monitoring and 

Assessment (GAMA) study, California, November 2006 to March 2007...............113

Table A5G. Quality-control summary of matrix-spike recoveries of radioactive 

constituents in samples collected for the Upper Santa Ana Watershed 

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

November 2006 to March 2007 ............................................................113

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

compounds, pesticides and pesticide degradates, pharmaceutical 

compounds, wastewater-indicator compounds, and constituents of special 

interest in samples collected for the Upper Santa Ana Watershed Groundwater 

Ambient Monitoring and Assessment (GAMA) study, California, November 2006 

to March 2007 ..............................................................................114

Table A7A. Quality-control summary for laboratory “set blanks” for pharmaceutical 

compounds corresponding to analyses of samples collected for the Upper 

Santa Ana Watershed Ground-Water Ambient Monitoring and Assessment 

(GAMA) study, California, November 2006 to March 2007..............................115

Table A7B. Quality-control summary for laboratory “set spikes” for pharmaceutical 

compounds corresponding to analyses of samples collected for the Upper 

Santa Ana Watershed Ground-Water Ambient Monitoring and Assessment 

(GAMA) study, California, November 2006 to March 2007..............................115
viii

Abbreviations and Acronyms

AB Assembly Bill (through the California State Assembly)

CAS Chemical Abstracts Service (American Chemical Society)

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

LT-MDL long-term method detection level

MCL-CA maximum contaminant level (CDPH)

MCL-US maximum contaminant level (USEPA)

MDL method detection limit

MRL minimum reporting level

MU method uncertainty

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

na not available

nc sample not collected

NL-CA California notification level (CDPH)

NWIS National Water Information System (USGS)

PCFF-GAMA personal computer field forms program designed for GAMA sampling

QC quality control

RPD relative percent difference

RSD relative standard deviation

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

SMCL-CA secondary maximum contaminant level (CDPH)

SMCL-US secondary maximum contaminant level (USEPA)

SSMDC sample-specific minimum detectable concentration

TML Trace Metal Laboratory

TT-US Treatment Technique (USEPA)

US United States

USAW Upper Santa Ana Watershed GAMA study unit

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

included in ground-water quality assessment
ix

Abbreviations and Acronyms—Continued

Organizations

CDPH California Department of Public Health

DWR California Department of Water Resources

LLNL Lawrence Livermore National Laboratory

MWH Montgomery Watson-Harza Laboratory

NAWQA National Water Quality Assessment (USGS)

NWQL National Water Quality Laboratory (USGS)

SWRCB State Water Resources Control Board (California)

USEPA U.S. Environmental Protection Agency

USGS U. S. Geological Survey

Selected Chemical Names

CaCO3 calcium carbonate

CO3

–2 carbonate

DOC dissolved organic carbon

HCl hydrochloric acid

HCO3

– bicarbonate

MTBE methyl tert-butyl ether

NDMA N-nitrosodimethylamine

PCE tetrachloroethene

TCP trichloropropane

TDS total dissolved solids

VOC volatile organic compound

Units of Measure

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

atmosphere of pressure per gram of water) 

ft foot (feet)

L liter

mg milligram

mg/L milligrams per liter 

mi2 square mile

mL milliliter

μg/L micrograms per liter

μL microliter

μm micrometer

pCi/L picocuries per liter

δi

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

lighter isotope of that element, relative to a standard reference material, expressed 

in per mil (per thousand)
x

Abbreviations and Acronyms—Continued

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).

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

25°C).

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

or micrograms per liter (μg/L). 
Abstract 

Ground-water quality in the approximately 1,000-squaremile Upper Santa Ana Watershed study unit (USAW) was 

investigated from November 2006 through March 2007 

as part of the Priority Basin Project of the Groundwater 

Ambient Monitoring and Assessment (GAMA) Program. 

The GAMA Priority Basin project was developed in response 

to the Groundwater Quality Monitoring Act of 2001, and is 

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

cooperation with the California State Water Resources Control 

Board (SWRCB). 

The Upper Santa Ana Watershed study was designed to 

provide a spatially unbiased assessment of raw ground-water 

quality within USAW, as well as a statistically consistent 

basis for comparing water quality throughout California. 

Samples were collected from 99 wells in Riverside and San 

Bernardino Counties. Ninety of the wells were selected using 

a spatially distributed, randomized grid-based method to 

provide statistical representation of the study unit (grid wells). 

Nine wells were selected to provide additional understanding 

of specific water-quality issues identified within the basin 

(understanding wells).

The ground-water samples were analyzed for a 

large number of organic constituents (volatile organic 

compounds [VOCs], pesticides and pesticide degradates, 

pharmaceutical compounds, and potential wastewaterindicator compounds), constituents of special interest 

(perchlorate, N-nitrosodimethylamine [NDMA], 1,4-dioxane, 

and 1,2,3-trichloropropane [1,2,3-TCP]), naturally occurring 

inorganic constituents (nutrients, major and minor ions, 

and trace elements), radioactive constituents, and microbial 

indicators. Naturally occurring isotopes (tritium, carbon-14, 

and stable isotopes of hydrogen and oxygen in water) and 

dissolved noble gases also were measured to help identify 

sources and ages of the sampled ground water. Dissolved 

gases, and isotopes of nitrogen gas and of dissolved nitrate 

also were measured in order to investigate the sources and 

occurrence of nitrate in the study unit. In total, nearly 400 

constituents and water-quality indicators were investigated for 

this study.

This study did not attempt to evaluate the quality of water 

delivered to consumers; after withdrawal from the ground, 

water typically is treated, disinfected, and (or) blended with 

other waters to maintain acceptable water quality. Regulatory 

thresholds apply to treated water that is served to the 

consumer, not to raw ground water. However, to provide some 

context for the results, concentrations of constituents measured 

in the raw ground water were compared with regulatory and 

non-regulatory health-based thresholds established by the U.S. 

Environmental Protection Agency (USEPA) and the California 

Department of Public Health (CDPH) and thresholds 

established for aesthetic concerns (secondary maximum 

contaminant levels, SMCL-CA) by CDPH.

Volatile organic compounds (VOCs) were detected 

in more than 80 percent of USAW grid wells. Most VOCs 

detected were at concentrations far less than thresholds 

established for drinking water to protect human health; 

however, six wells had VOC concentrations above 

health-based thresholds. Twenty-four of the 85 VOCs 

investigated were detected in the study unit;11 were 

detected in more than 10 percent of the wells. The VOCs 

detected above health-based thresholds in at least one well 

were dibromochloropropane (DBCP), tetrachloroethene 

(PCE), trichloroethene (TCE), carbon tetrachloride, and 

1,1-dichoroethene. 

Pesticide compounds were detected in more than 

75 percent of the grid wells. However, of the 134 different 

pesticide compounds investigated, 13 were detected at 

concentrations greater than their respective long-term method 

detection limits, and only 7 compounds (all herbicides or 

herbicide degradates) were detected in more than 10 percent 

of the wells. No pesticide compound was detected above its 

health-based threshold, although thresholds exist for fewer 

than half of the pesticide compounds investigated.

Samples were analyzed for a suite of 69 chemicals 

identified as “potential wastewater indicators.” However, 

data for this suite of chemicals are not presented in this report 

because inconsistent results for quality-control samples 

collected and analyzed using this analytical method suggested 

that the results were unreliable.

Ground-Water Quality Data in the Upper Santa Ana 

Watershed Study Unit, November 2006–March 2007: 

Results from the California GAMA Program

By Robert Kent and Kenneth Belitz
2 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Samples were analyzed for 14 pharmaceutical 

compounds. Four compounds were detected in ground-water 

samples, but no compound was detected in more than five 

samples. All pharmaceutical compound concentrations were 

low compared to their typical prescription dosages. 

Samples were analyzed for about 50 inorganic 

constituents. These include nutrients, major and minor ions, 

and trace elements, most of which occur naturally in ground 

water. Nitrate, a nutrient species of nitrogen, was detected at 

concentrations above its health-based threshold in 29 percent 

of the grid wells for which it was sampled. Concentrations 

of other forms of nitrogen detected were below health-based 

thresholds. Concentrations of total dissolved solids were 

greater than thresholds set for aesthetic concerns in nearly 

40 percent of the wells for which total dissolved solids 

were sampled. Concentrations of chloride and sulfate were 

greater than such aesthetic thresholds in 3 wells and 1 well, 

respectively. Concentrations of all trace elements detected 

in samples from USAW wells were below health-based 

thresholds, except arsenic (above a threshold in 2 wells), 

boron (1 well), molybdenum (2 wells) and vanadium (2 wells). 

Concentrations of two additional trace elements—iron 

and manganese—were greater than their non-enforceable 

thresholds set for aesthetic concerns in 1 and 2 wells, 

respectively. Perchlorate, an inorganic constituent of special 

interest, was detected in two-thirds of the wells, and 11 wells 

contained perchlorate concentrations at or above its healthbased threshold.

 Radon-222 activities in more than half of the wells 

sampled for this radioactive isotope were above the proposed 

USEPA maximum contaminant level (MCL-US), but none 

were above the proposed alternative MCL-US. All other 

detections of radioactive constituents were below healthbased thresholds except one gross-alpha measurement of 

17.3 picocuries per liter (72-hour count). Total coliforms, 

a bacterial indicator, were detected in 1 out of 32 wells for 

which total coliforms were sampled.

Introduction 

Ground water comprises nearly half of the water used 

for public supply in California (Hutson and others, 2004). 

To assess the quality of ground water in aquifers used for 

drinking-water supply and establish a program for monitoring 

trends in ground-water quality, the State Water Resources 

Control Board (SWRCB), in collaboration 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 GAMA program consists 

of three projects: Priority Basin, conducted by the USGS 

(http://ca.water.usgs.gov/gama/); Voluntary Domestic Well 

Assessment, conducted by the SWRCB; and Special Studies, 

conducted by LLNL. 

The SWRCB initiated the GAMA Priority Basin project 

in response to the Ground-Water Quality Monitoring Act of 

2001 (Sections 10780-10782.3 of the California Water Code, 

Assembly Bill 599). AB 599 is a public mandate to assess and 

monitor the quality of ground water used as public supply for 

municipalities in California. The project is a comprehensive 

assessment of statewide ground-water quality designed to help 

better understand and identify risks to ground-water resources 

and to increase the availability of information about groundwater quality to the public. As part of the AB 599 process, 

the USGS, in collaboration with the SWRCB, developed the 

monitoring plan for the project (Belitz and others, 2003; State 

Water Resources Control Board, 2003). A key aspect of the 

project is inter-agency collaboration and cooperation with 

local water agencies and well owners. Local participation in 

the project is entirely voluntary.

The GAMA Priority Basin project is unique because 

the data collection methods include analyses that can detect 

an extensive number of chemical constituents at very low 

concentrations, analyses that are not normally available. 

A broader understanding of ground-water composition 

will be especially useful for providing an early indication 

of changes in water quality and for identifying the natural 

and human factors affecting water quality. Additionally, the 

GAMA Priority Basin Assessment project will analyze a 

suite of constituents more extensive than that required by 

the California Department of Public Health (CDPH). An 

understanding of the occurrence and distribution of these 

constituents is important for the management and protection of 

ground-water resources.

 The range of hydrologic, geologic, and climatic 

conditions that exist in California must be considered in an 

assessment of ground-water quality. Belitz and others (2003) 

partitioned the state conceptually into 10 hydrogeologic 

provinces (fig. 1), each with distinctive hydrologic, 

geologic, and climatic characteristics, and representative 

regions in all 10 provinces were included in the project 

design. Eighty percent of California’s approximately 16,000 

public-supply wells are located in ground-water basins within 

these hydrologic provinces. These ground-water basins, 

defined by the California Department of Water Resources, 

generally consist of fairly permeable, unconsolidated deposits 

of alluvial or volcanic origin (California Department of Water 

Resources, 2003). Ground-water basins were prioritized 

for sampling on the basis of the number of public-supply 

wells in the basin, with secondary consideration given to 

municipal ground-water use, agricultural pumping, the number 

of formerly leaking underground fuel tanks, and pesticide 

applications within the basins (Belitz, and others, 2003). 
Introduction 3

Basin and Range

Central

Valley

Klamath

Mountains

Desert

Cascades and

Modoc Plateau

Transverse Ranges and

Selected Peninsular Ranges

Southern Coast

Ranges

Sierra

Nevada

Northern

Coast

Ranges

San Diego

Drainages

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.

Upper Santa Ana

Watershed

(figure 2)

Figure 1. Hydrogeologic provinces of California and the location of the Upper Santa Ana Watershed 

Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California.
4 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

In addition, some ground-water basins or groups of adjacent 

similar basins with relatively few public-supply wells were 

assigned high priority so that all hydrogeologic provinces 

would be represented in the subset of basins sampled. The 

116 priority basins were grouped into 35 study units. Some 

areas not in the ground-water basins were included in several 

of the study units to represent the 20 percent of public-supply 

wells not located in the ground-water basins. The Upper Santa 

Ana Watershed GAMA study unit, hereinafter referred to as 

USAW, contains three ground-water basins. The largest of 

these 3 basins—the Upper Santa Ana Valley Groundwater 

Basin—contains 9 subbasins recognized by the California 

Department of Water Resources. The USAW study unit 

lies within the Transverse and Selected Peninsular Ranges 

hydrogeologic province (fig. 1) (Belitz, and others, 2003). 

Three types of water-quality assessments are being 

conducted using the data collected in each study unit: 

(1)Status: assessing the current quality of the ground-water 

resource, (2) Trends: detection of changes in ground-water 

quality, and (3) Understanding: identifying the natural and 

human factors affecting ground-water quality (Kulongoski 

and Belitz, 2004). This report is one of a series of reports 

presenting the status of current water quality conditions in 

each study unit; previous reports in the series include Wright 

and others (2005), Kulongoski and others (2006), Bennett and 

others (2006), Kulongoski and Belitz (2007), Fram and Belitz 

(2007), Dawson and others (2008), Landon and Belitz (2008), 

and Ferrari and others (2008). Subsequent interpretive reports 

will address the trends and understanding aspects of the waterquality assessments.

Purpose and Scope

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

study design and study methods, (2) to present the results of 

quality-control tests, and (3) to present the analytical results 

for ground-water samples collected in USAW. Ground-water 

samples were analyzed for organic, inorganic, and microbial 

constituents, water-quality indicators, and chemical tracers. 

The chemical and microbial data presented in this report were 

evaluated by comparing them to state and federal drinking 

water regulatory and other health-based standards that are 

applied to treated drinking water. Regulatory thresholds 

considered for this report are those established by the United 

States Environmental Protection Agency (USEPA) and the 

California Department of Public Health (CDPH). The data 

presented in this report are intended to characterize the quality 

of untreated ground-water resources within the study unit, 

not the treated drinking water delivered to consumers by 

water purveyors. Discussions of the factors that influence 

the distribution and occurrence of the constituents detected 

in ground-water samples will be the subject of subsequent 

publications.

Hydrogeologic Setting 

The Upper Santa Ana Watershed study unit (USAW) 

covers approximately 1,000 square-miles in Riverside and 

San Bernardino Counties, California (fig. 2), and lies within 

the Transverse Ranges and Selected Peninsular Ranges 

hydrogeologic province (fig. 1). USAW includes three groundwater basins, as defined by the California Department of 

Water Resources (DWR) (fig. 2) (California Department of 

Water Resources, 2003, 2006a, 2006b): San Jacinto, Elsinore, 

and the Upper Santa Ana Valley. The Upper Santa Ana 

Valley Groundwater Basin includes nine subbasins defined 

by DWR (fig. 3): Bunker Hill, Cajon, Rialto-Colton, Chino, 

Cucamonga, Yucaipa, San Timoteo, Riverside-Arlington, and 

Temescal (California Department of Water Resources, 2004a, 

2004b, 2004c, 2004d, 2004e, 2004f, 2004g, 2006c, 2006d).

The area encompassed by USAW has also been 

divided into 36 Groundwater Management Zones using 

recently obtained hydrogeochemical data and ground-water 

management objectives (Wildermuth Environmental Inc., 

1999; Wildermuth Environmental Inc., 2000). The Santa Ana 

Regional Water Quality Control Board has adopted these 

Management Zone delineations by amendment (California 

Regional Water Quality Control Board, 2004) to their Water 

Quality Control Plan (California Regional Water Quality 

Control Board, Santa Ana Region, 1995). 

Topography in the USAW region varies from about 500 ft 

above sea level in the area around Prado Dam in Corona to 

over 10,000 ft in the San Bernardino Mountains near Big Bear 

Lake (fig. 2). Most of the valley floors are less than 2,000 ft 

above sea level in all three ground-water basins in the study 

unit. The 65 grid wells sampled in the Upper Santa Ana Valley 

Groundwater Basin (figs. 2 and 3) are located at altitudes 

between 600 and 3,700 ft. An understanding well was sampled 

in the mountains approximately 2.5 miles northeast of this 

basin at an altitude of almost 5,000 ft. The four grid wells 

sampled in the Elsinore Groundwater Basin are at altitudes 

between 1,250 and 1,300 ft. Altitudes of the 21 grid wells 

sampled in the San Jacinto Groundwater Basin varied between 

about 1,450 and 1,650 ft. The climate of the USAW region is 

Mediterranean, with hot, dry summers and cool, wet winters. 

Average annual precipitation ranges from 10 to 24 inches in 

the valleys and from 24 to 48 inches in the mountains.
Introduction 5

Figure 2. California Department of Water Resources defined ground-water basins and major hydrologic features in the Upper 

Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California.

Big Bear Lake

Bautista Creek

EXPLANATION

91

60

10

15

5

15

15

215

215

10

ORANGE CO

RIVERSIDE CO

LOS

ANGELES

CO

SAN BERNARDINO CO

San Juan Creek

California Aqueduct

Arroyo

Trabuco

Santa Ana River

MWD Upper

Feeder

MWD Lower

Feeder

San Gabriel River

Deep Creek

Colorado River Aqueduct

Lytle Creek

Santa Ana River

Mojave River

Bear Creek

Chino Creek

Perris

Dam

Santiago

Dam

UPPER SANTA

ANA VALLEY

SAN

JACINTO

ELSINORE

San Bernardino

Riverside

Lake

Elsinore

Hemet

Railroad

Canyon

Dam

San Jacinto River

San Gorgonio River

Prado Dam

Wetlands

Mathews

Dam

0 10 20 Miles

0 10 20 Kilometers

Shaded relief derived from U.S. Geological Survey 

National Elevation Dataset, 2006, 

Albers Equal Area Conic Projection

California Department of Water Resources ground-water basins 

Upper Santa Ana Valley San Jacinto

Water bodies County boundaries

Aqueducts

Wetlands Major roads

Rivers

Elsinore
6 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

@

ORANGE CO

RIVERSIDE CO

LOS

ANGELES

CO

SAN BERNARDINO CO

0 10 20 Miles

0 10 20 Kilometers

Shaded relief derived from U.S. Geological Survey 

National Elevation Dataset, 2006, 

Albers Equal Area Conic Projection

EXPLANATION

Faults—Dashed where concealed,

 queried where uncertain ?

Upper Santa Ana Valley

 ground-water basin boundary

Upper Santa Ana Valley

 ground-water subbasin boundary

SAN

JACINTO

ELSINORE

TEMESCAL

SAN

TIMOTEO

YUCAIPA RIVERSIDEARLINGTON

CHINO

CUCAMONGA BUNKER

HILL

RIALTOCOLTON

CAJON

Figure 3. California Department of Water Resources defined ground-water subbasins of the Upper Santa Ana Valley ground-water 

basin in the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California.
Methods 7

Aquifers of the Upper Santa Ana Valley Groundwater 

Basin are generally unconfined and comprise several subbasins 

filled with alluvial deposits eroded from the surrounding 

mountains (Hamlin and others, 2005). The thickness of these 

deposits ranges from less than 200 ft to more than 1,000 ft 

(Dutcher and Garrett, 1963). Faults play an important role in 

the ground-water flow system here. The San Andreas Fault, 

which lies along the base of the San Bernardino Mountains, 

and other faults, which lie along the base of the San Gabriel 

Mountains and Chino Hills, bound the valley flow system on 

three sides (fig. 3) (Hamlin and others, 2002). Other faults, 

such as the San Jacinto Fault, divide the Upper Santa Ana 

Valley Groundwater Basin into its subbasins. These interior 

faults locally restrict ground-water flow and control the 

location of ground-water discharge (Izbicki and others, 1998; 

Woolfenden and Kadhim, 1997). 

Ground-water flow in aquifers of the Elsinore Basin 

is also affected by several faults dividing the alluvial and 

lacustrine sediments. Floodplain deposits in the interior of the 

valley typically reach a thickness of about 200 ft, while the 

fine-grained lacustrine deposits in the zone of inundation of 

Lake Elsinore reach 800 ft in thickness (California Department 

of Water Resources, 1981).

Aquifers of the San Jacinto Groundwater Basin are 

generally unconfined and consist of a series of interconnected 

alluvium-filled valleys bounded by steep-sided bedrock 

mountains and hills (Hamlin and others, 2005). The deposits 

in these valleys typically are 200 to 1,000 ft thick (Eastern 

Municipal Water District, 2002). 

Two stipulated judgments broadly adjudicated water 

rights in the Santa Ana Basin (upper and lower) in 1969 

(Orange County Water District v. City of Chino, Superior 

Court No. 117628; Western Municipal Water District of 

Riverside County v. East San Bernardino County Water 

District, Superior Court No. 78426). Currently, the Santa Ana 

Watermaster compiles hydrologic and water-quality data in 

annual reports, and the Santa Ana Watershed Project Authority, 

a Joint Powers Authority, classified as a Special District 

(government agency), plans and builds facilities to protect the 

water quality of the Santa Ana River Watershed. In addition, 

the Chino Basin was separately adjudicated in 1978; the Chino 

Basin Watermaster was directed to establish a comprehensive 

basin management program that responds to declines in the 

quantity and quality of ground water there (Miller and others, 

2007).

Methods 

Methods used for the GAMA program were selected 

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

plan suitable for statistical analysis, (2) collect samples in 

a consistent manner, (3) analyze samples using proven and 

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

ground-water data, and (5) maintain data securely and with 

relevant documentation.

Study Design

The wells selected for sampling in this study reflect 

the combination of two well-selection strategies. Ninety 

wells were selected using a randomized grid-based method 

(Scott, 1990) in order to provide a statistically unbiased, 

spatially distributed assessment of the quality of groundwater resources used for public drinking-water supply. Nine 

additional wells were selected to increase sampling density 

in several areas for a better understanding of specific groundwater quality issues in the study unit.

To select an unbiased, spatially distributed network of 

wells, the locations of wells listed in the statewide databases 

maintained by the CDPH and USGS were plotted on a 

regional map. A grid of 107 equal-area cells (10 mi2) was 

then drawn over the USAW map with the objective to select 

one public-supply well to sample per grid cell. For the 

purposes of this study, the Upper Santa Ana Valley (figs. 2

and 3) was divided into four study areas by combining the 

nine DWR-defined subbasins: Bunker Hill/Cajon/RialtoColton, Cucamonga/Chino, Riverside-Arlington/Temescal, 

Yucaipa/San Timoteo (fig. 4). The entire San Jacinto Basin 

constituted a fifth USAW study area. The relatively small 

(approximately 40 mi2) Elsinore ground-water basin was not 

divided into cells; this sixth and final study area was sampled 

by picking four wells (approximately one well per 10 mi2) 

spread throughout the basin to represent four “equivalent 

cells” (fig. 4). These four wells are treated the same as 

wells representing grid cells for the purpose of statistical 

characterization of water quality in the USAW study unit.

Ninety of the 107 grid cells were sampled in USAW. 

Seventeen grid cells were not sampled because some had no 

wells or because permission to sample was not granted. If a 

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

well was randomly assigned a number. The well having the 

lowest assigned number that met basic sampling criteria (for 
8 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

ORANGE CO

RIVERSIDE CO

LOS

ANGELES

CO

SAN BERNARDINO CO

0 10 20 Miles

0 10 20 Kilometers

Shaded relief derived from U.S. Geological Survey 

National Elevation Dataset, 2006, 

Albers Equal Area Conic Projection

EXPLANATION

Sampled Wells Sampled subareas

Understanding well

 and identifier

Grid well

 and identifier

Bunker Hill/Cajon/Riato-Colton

Cucamonga/Chino

Riverside-Arlington/Temscal

San Jacinto

Yucaipa/San Timoteo

Elsinore

Grid cell

USAWY-09

USAWY-08

USAWY-07

USAWY-06

USAWY-04 USAWY-05

USAWY-03

USAWY-02

USAWY-01

USAWU-09

USAWU-08

USAWU-07

USAWU-06

USAWU-05

USAWU-04

USAWU-03

USAWU-02

USAWU-01

USAWU-01

USAWS-21

USAWS-20

USAWS-19

USAWS-18

USAWS-17

USAWS-16

USAWS-15

USAWS-14

USAWS-13

USAWS-12

USAWS-11

USAWS-10

USAWS-09

USAWS-08

USAWS-07

USAWS-06

USAWS-05

USAWS-04

USAWS-03

USAWS-02

USAWS-01

USAWR-12

USAWR-11

USAWR-10

USAWR-09

USAWR-08

USAWR-07

USAWR-06

USAWR-05

USAWR-04

USAWR-03

USAWR-02

USAWR-01

USAWE-04

USAWE-04

USAWE-03

USAWE-02

USAWE-01

USAWC-25

USAWC-24

USAWC-23

USAWC-22

USAWC-21

USAWC-20

USAWC-19

USAWC-18

USAWC-17

USAWC-16

USAWC-15

USAWC-14 USAWC-13

USAWC-12

USAWC-10 USAWC-11

USAWC-09

USAWC-08

USAWC-07

USAWC-06

USAWC-05

USAWC-04

USAWC-03

USAWC-02

USAWC-01

USAWB-19

USAWB-18

USAWB-17

USAWB-16 USAWB-15

USAWB-14

USAWB-13

USAWB-12

USAWB-11

USAWB-10

USAWB-09

USAWB-08

USAWB-07

USAWB-06

USAWB-05

USAWB-04

USAWB-03

USAWB-02

USAWB-01

Figure 4. Distribution of study unit grid cells and the location of sampled grid wells and understanding wells in the Upper Santa 

Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California.
Methods 9

example, sampling point prior to treatment, capability to pump 

for several hours, and available well-construction information) 

and for which permission to sample could be obtained was 

then sampled. If a grid cell contained no accessible publicsupply wells, domestic and irrigation wells were considered. 

An attempt was made to select domestic and irrigation wells 

with depths and screened intervals similar to those in publicsupply wells in the area. In this fashion, a well was selected 

in each cell to provide a spatially distributed, randomized 

monitoring network for each study area. Wells sampled 

as part of the randomized grid-cell network (including the 

four equivalent cells sampled in the Elsinore study area) are 

hereinafter referred to as “grid wells”. Grid wells in USAW 

were numbered in the order they were sampled in each study 

area with the prefixes “USAWB” (wells in the Bunker Hill/

Cajon/Rialto-Colton study area [19 grid wells sampled/out 

of 20 grid cells delineated]), “USAWC” (Cucamonga/Chino 

[25/27]), “USAWE” (Elsinore [4/4]), “USAWR” [RiversideArlington/Temescal (12/13)], “USAWS” [San Jacinto (21/31)], 

or “USAWY” [Yucaipa/San Timoteo (9/12)] (fig. 4).

In addition to the grid wells, nine “understanding” wells 

were sampled to attempt to answer specific questions in the 

study unit. Two understanding wells were sampled to fill in 

data gaps along flow paths in the Cucamonga-Chino study 

area. Three understanding wells were sampled to evaluate 

a conceptual flow transect that starts at the northern end of 

the Rialto-Colton Basin (fig. 3), progresses approximately 

southward until it reaches the Riverside-Arlington Basin, and 

then turns to the southwest across this basin. Understanding 

wells were assigned the prefix “USAWU” and were numbered 

in the order of sample collection; they were not included in the 

statistical characterization of water quality in USAW. 

Table 1 provides the GAMA-id (alphanumeric 

identification number) for each well, along with the date 

sampled, sampling schedule, well elevation, and wellconstruction information. All samples but one were collected 

from November 27, 2006, to February 15, 2007; one was 

collected from well USAWC-25 on March 28, 2007. Groundwater samples were collected from 80 public-supply wells, 9 

irrigation wells, 5 desalination wells, 3 monitoring wells, 1 

domestic well, and a (recreation use) well used to fill ponds at 

a camping resort. 

Well locations and identifications were verified using 

GPS, 1:24,000 scale USGS topographic maps, comparison 

with existing well information in USGS and CDPH databases, 

and information provided by well owners. Driller’s logs for 

wells were obtained when available. 

The wells in USAW were sampled using a tiered 

analytical approach. All wells were sampled for a standard 

set of constituents, including VOCs, pesticides and pesticide 

degradates, pharmaceutical compounds, potential wastewater 

indicators, perchlorate, stable isotopes of hydrogen and 

oxygen in water, dissolved noble gases, tritium, and helium 

isotopes. The standard set of constituents was termed the 

“fast” schedule (table 2). Wells on the “intermediate” schedule 

were sampled for all the constituents on the fast schedule, 

plus nutrients, major and minor ions and trace elements, 

standard dissolved gases, isotopes of nitrogen and oxygen 

in nitrate, isotopes of nitrogen in nitrogen gas, and carbon 

isotopes. Wells on the “slow” schedule were sampled for all 

the constituents on the intermediate schedule, plus dissolved 

organic carbon, NDMA, 1,2,3-TCP, 1,4-dioxane, tritium, the 

redox species of arsenic, chromium, and iron, radioactive and 

microbial constituents (table 2). Fast, intermediate, and slow 

refer to the time required to sample the well for all the analytes 

on the schedule. 

Some of the additional wells sampled for better 

understanding were analyzed on a sampling schedule 

termed “topical”. Overall, the topical sampling schedule 

included fewer constituents than the fast schedule, but was 

designed to expand the understanding of nitrate occurrence 

in USAW ground water The topical schedule consisted of 

VOCs, perchlorate, nutrients, major and minor ions and trace 

elements, standard dissolved gases and noble gases, isotopes 

of nitrogen and oxygen in nitrate, isotopes of nitrogen in 

nitrogen gas, carbon isotopes, and tritium/helium age dates. 

In USAW, 42 of the ground-water wells were sampled 

on the fast schedule, 18 were sampled on the intermediate 

schedule, and 32 on the slow schedule. Seven wells were 

sampled on the topical schedule. However, analyses for 

dissolved organic carbon and potential wastewater indicators 

were added for 3 of the 7 topical samples to further investigate 

the occurrence of nitrate in these wells. 

Sample Collection and Analysis

Ground-water samples were collected using standard and 

modified USGS protocols (Koterba and others, 1995; U.S. 

Geological Survey, variously dated) and protocols described 

by Weiss (1968), Shelton and others (2001), and Ball and 

McClesky (2003a, 2003b). The sample-collection method 

used for fast, intermediate, and topical sampling schedules 

was slightly different than that used for slow sampling and 

is described by Wright and others (2005). The sampling 

protocols ensure that a representative sample of ground water 

is collected at each site, and that the samples are collected and 

handled in a way that minimizes the potential to contaminate 

samples. The methods used to collect samples are described in 

the Appendix.
10 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Tables 3A-L list the compounds analyzed in each 

constituent class. Ground-water samples were analyzed 

for 85 VOCs (table 3A), 135 compounds consisting of 

pesticides, pesticide degradates, and caffeine (tables 3B and 

3C), 14 pharmaceutical compounds (table 3D), 69 potential 

wastewater-indicator compounds (table 3E), 4 constituents 

of special interest (table 3F), 5 nutrients (species of nitrogen 

and phosphorus), and dissolved organic carbon (table 3G), 

10 major and minor ions, laboratory-determined alkalinity, 

silica and total dissolved solids (table 3H), 25 trace elements 

(table 3H), arsenic, iron, and chromium species (table 3I), 

stable isotopes of water, stable isotopes of nitrate and 

nitrogen gas, 8 radioactive constituents, including tritium 

and carbon-14 (table 3J), standard dissolved gases and noble 

gases, (table 3K), and 4 microbial constituents (table 3L). 

The methods used to analyze samples are listed in Appendix 

table A1. 

Data Reporting

The methods and conventions used for reporting the 

data are described in the Appendix. Eighteen water-quality 

constituents were measured by more than one analytical 

method. When an analyte is measured by more than one 

method in the same water medium (in filtered or in unfiltered 

water), the results are considered as duplicated measurements 

of the same parameter, and a preferred analytical method is 

identified (listed first in the column of analytical schedules of 

Appendix table A2). All results available at the time that this 

report was prepared are presented here, including duplicated 

measurements of the same parameter.

Quality Assurance 

The quality-assurance procedures used for this study 

follow the protocols described in the USGS NWQL qualityassurance plan (U.S. Geological Survey, variously dated; 

Maloney, 2005; Pirkey and Glodt, 1998) and the protocols 

used by the USGS NAWQA program (Koterba and others, 

1995). Quality-control (QC) samples were collected to 

evaluate bias and variability of the water chemistry data 

that may have resulted from sample collection, processing, 

storage, transportation, and laboratory analysis. QC samples 

collected in the USAW study include source-solution blanks, 

field blanks, replicates, and matrix and surrogate spikes. The 

quality-assurance procedures are described in the Appendix.

Water-Quality Results 

Ground-water samples collected in USAW were analyzed 

for up to 382 distinct constituents, and more than half (202) 

of these constituents were not detected in any of the wells 

(tables 3A-L). The results tables (tables 4-17) present only the 

constituents that were detected and list only wells at which 

at least one constituent was detected. For constituent classes 

that were analyzed at all of the grid wells, the tables include 

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), and the total number of constituents detected at 

each well. Results from the nine additional wells sampled for 

understanding are presented in tables 4-17, but these results 

were excluded from the detection frequency calculations to 

avoid statistically over-representing the areas where these 

understanding wells were located. Reported detections 

of constituents detected at concentrations less than their 

respective long-term method detection limit (LT-MDL) were 

also excluded from detection frequency calculations.

Table 4 includes water-quality indicators measured in 

the field and at the NWQL, while tables 5 through 17 present 

the results of ground-water analyses organized by compound 

classes: 

• Organic Constituents

• VOCs (table 5)

• Pesticides, pesticide degradates, and caffeine 

(table 6)

• Pharmaceutical compounds (table 7)

• Constituents of special interest (table 8)

• Inorganic constituents (and dissolved organic carbon)

• Nutrients and dissolved organic carbon (table 9)

• Major and minor ions, silica, and total dissolved 

solids (table 10)

• Trace elements (table 11)

• Arsenic, iron, and chromium species (table 12)

• Inorganic tracer constituents

• Stable isotopes and tritium and carbon-14 activities 

(table 13)

• Standard dissolved gases (table 14)

• Noble gases and helium isotopes (table 15)

• Radioactive constituents (table 16)

• Microbial indicators (table 17)
Water-Quality Results 11

Quality-Control Sample Results

Results of quality-control analyses (blanks, replicates, 

matrix spikes, and surrogates) were used to evaluate the bias 

and variability of the data for the ground-water samples. 

Matrix spike recoveries for a number of organic constituents 

were lower than the acceptable limits, which may indicate a 

low bias for these constituents, and they may not have been 

detected in some samples if they were present at very low 

concentrations. The quality-control results are described in the 

Appendix.

Comparison Thresholds

Concentrations of constituents detected in ground-water 

samples were compared with CDPH and USEPA drinkingwater regulatory and health-based thresholds (California 

Department of Public Health, 2007a; U.S. Environmental 

Protection Agency, 2006) as a way to give context to the 

detected concentrations. The chemical and microbial data 

presented in this report are meant to characterize the quality 

of the untreated ground-water resources within USAW and are 

not intended to represent the treated drinking water delivered 

to consumers by water purveyors. The chemical and microbial 

composition of treated drinking water may differ from 

untreated ground water because treated drinking water may be 

disinfected, filtered, mixed with other waters, and exposed to 

the atmosphere before being delivered to consumers. 

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 constituents not regulated by the USEPA and has 

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 exceeding MCL-US 

or MCL-CA thresholds in samples collected for the 

GAMA Priority Basin Assessment project.

• 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 at concentrations above thresholds trigger 

mandatory water treatment to reduce the corrosiveness 

of water to plumbing components. The action levels 

established by the USEPA and CDPH are the same, 

thus the thresholds are labeled “AL-US” in this report.

• TT – Treatment Technique. Legally enforceable 

standards that apply to public-water systems and are 

designed to protect public health by limiting the levels 

of copper, lead, and microbial constituents in drinking 

water. TT requirements are applied when water 

delivered to consumers exceeds specified action levels. 

Detections of microbial constituents at concentrations 

above thresholds trigger additional mandatory 

disinfection during water treatment. The action levels 

established by the USEPA and CDPH are the same, 

thus the thresholds are labeled “TT-US” in this report.

• SMCL – Secondary Maximum Contaminant Level.

Non-enforceable standards applied to constituents that 

affect the aesthetic qualities of drinking water, such as 

taste, odor, and color, or technical qualities of drinking 

water, such as scaling and staining. Both the USEPA 

and CDPH define SMCLs, but unlike MCLs, SMCLs 

established by CDPH may be less stringent than those 

established by USEPA. SMCLs established by CDPH 

(SMCL-CAs) are used in this report for all constituents 

that have SMCL-CA values. The SMCL-US is used for 

pH because no SMCL-CA has been defined.

• NL – Notification Level. Health-based notification 

levels established by CDPH for some of the 

constituents in drinking water that lack MCLs 

(NL-CA). If a constituent is detected above its 

NL-CA, State law requires timely notification of 

local governing bodies and recommends consumer 

notification.

• HAL – Lifetime Health Advisory Level. The 

maximum concentration of a constituent at which its 

presence in drinking water is not expected to cause any 

adverse carcinogenic effects for a lifetime of exposure. 

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

are calculated assuming consumption of 2 liters of 

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

(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 established by the USEPA (RSD5-US).
12 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Concentrations of constituents in ground-water 

samples that had MCLs were compared to the MCL-US or 

MCL-CA. Constituents with SMCLs were compared with 

the SMCL-CA. For chloride, sulfate, specific conductance, 

and total dissolved solids, CDPH defines a “recommended” 

and an “upper” SMCL-CA; concentrations of these 

constituents in ground-water samples were compared with 

both levels. The SMCL-US for these constituents equals 

the recommended SMCL-CA. Detected concentrations of 

constituents that lack MCLs and SMCLs were compared 

to NL-CAs. For constituents that lack an MCL, SMCL, 

or NL-CA, detected concentrations were compared to the 

HAL-US. For constituents that lack an MCL, SMCL, NL-CA, 

or HAL-CA, detected concentrations were compared to the 

RSD5-US. This hierarchy of comparison thresholds means 

that for constituents that have multiple types of established 

thresholds, the threshold used for comparison may not have 

the lowest concentration. The comparison thresholds used in 

this report are listed in tables 3A-L for all constituents and in 

tables 4-17 for constituents detected in ground-water samples 

from USAW. Detections of constituents at concentrations 

greater than the selected comparison threshold are marked 

with asterisks in tables 4-17. Not all constituents analyzed for 

this study have established thresholds available. 

Ground-Water-Quality Data

Results from analyses of untreated ground-water samples 

from USAW are presented in tables 4 through 17. A brief 

description of these results is given here.

Water-Quality Indicators

Field and laboratory measurements of dissolved oxygen, 

pH, specific conductance, alkalinity, and associated parameters 

are presented in table 4. Dissolved oxygen and alkalinity 

are used as indicators of natural processes that control water 

chemistry. Specific conductance is a measure of electrical 

conductivity of the water and is proportional to the amount of 

dissolved salts in the water. The pH value indicates the acidity 

of the water. Specific conductance measured in the field was 

above the recommended SMCL-CA threshold in 25 grid wells 

and above the upper threshold in 7 wells. pH measured in the 

field was above the recommended SMCL- US in 4 grid wells 

and 1 understanding well.

Organic Constituents

Volatile organic compounds (VOC) are in paints, 

solvents, fuels, fuel additives, refrigerants, fumigants, and 

disinfected water, and are characterized by inherent physical 

and chemical properties that allow them to move between 

water and air. VOCs persist longer in ground water than 

in surface water because ground water is isolated from the 

atmosphere. Twenty-four of the eighty-five VOCs targeted 

for analysis in this study were detected in samples from 

USAW (table 5). An additional VOC, toluene, was detected 

in 5 samples. However, its concentrations in field blanks 

were similar to the concentrations in the samples, making 

its presence in USAW ground water questionable. One or 

more VOCs were detected in more than 80 percent of USAW 

grid wells. Of the 24 VOCs detected in the study unit, 11 

were detected “frequently” (in 10 percent or more of the grid 

wells): trichloromethane (chloroform), tetrachloroethene 

(PCE), trichloroethene (TCE), bromodichloromethane, 

1,2,4-trimethylbenzene, 1,1-dichloroethene, methyl 

tert-butyl ether (MTBE), cis-1,2-dichloroethene, 

dichlorodifluoromethane (CFC-12), trichlorofluoromethane 

(CFC-11), and 1,1-dichloroethane. 

Health-based thresholds exist for all 24 of the VOCs 

detected in samples from USAW, and most VOC detections 

were at concentrations well below these thresholds (table 5). 

However, five VOCs were detected at concentrations 

greater than their health-based threshold in at least one 

sample: tetrachloromethane (carbon tetrachloride), 

dibromochloropropane (DBCP), 1,1-dichloroethene, 

tetrachloroethene (PCE), and trichloroethene (TCE). 

At least one of these five compounds was detected at a 

concentration above its health-based threshold in samples 

from six USAW grid wells. Only two other VOCs were 

detected at concentrations within 10 percent of their healthbased thresholds: one such detection for each of the isomers 

1,1-dichloroethane and 1,2-dichloroethane.

Pesticides include herbicides, insecticides, and fungicides 

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

in agricultural, urban, and suburban settings. Thirteen of the 

134 pesticide compounds targeted for analysis in this study 

were detected in samples from USAW at concentrations 

greater than their respective long-term method detection limits 

(LT-MDL) (table 6). These compounds appear on table 6 in 

the order of detection frequency (greatest to least). Four of the 

compounds—atrazine, 2-chloro-4-isopropylamino-6-aminos-triazine, tebuthiuron, and metalaxyl—were measured by 

two different pesticide analytical methods. In these cases, 

the column of data for the preferred method appears first, 

and dictates the order on the table. The column of data for 

the non-preferred method is listed adjacent to (to the right 

of) the preferred-method column, regardless of the detection 

frequency by the non-preferred method. Atrazine and 

2-chloro-4-isopropylamino-6-amino-s-triazine were detected 

at concentrations greater than their respective LT-MDLs by 

both methods. Tebuthiuron and metalaxyl were detected at 

concentrations greater than their respective LT-MDLs only by 

one of the two methods.
Water-Quality Results 13

One or more pesticide compounds were detected in 

68 percent of USAW grid wells. Seven pesticide compounds 

were detected frequently (in more than 10 percent of the 

grid wells). All seven of these frequently detected pesticide 

compounds were herbicides or herbicide degradates: 

atrazine, simazine, 2-chloro-4-isopropylamino-6-aminos-triazine bromacil, diuron, 3,4-dicloroaniline, and 

2-chloro-6-ethylamino-4-amino-s-triazine. 

Table 6 lists an additional 13 pesticide compounds 

detected in USAW only at concentrations less than their 

respective LT-MDLs. The detection frequencies for these 

compounds appear as zeros on the table because the presence 

(or absence) of a compound below its LT-MDL cannot be 

reliably determined (Childress and others, 1999).

Health-based thresholds exist for 7 of the 13 pesticide 

compounds reliably detected in samples from USAW, 

and all pesticides detected were at concentrations below 

these thresholds. Only one pesticide detection came within 

10 percent of its health-based threshold; atrazine, which has a 

California MCL of 1 μg/L, was detected at a concentration of 

0.11 μg/L in one well (USAWR-01).

Potential wastewater indicators include chemicals 

used in pesticides, home maintenance, personal care, and 

industrial products that may have a variety of sources other 

than wastewater. Sixty-nine potential wastewater indicators 

were targeted for analysis in this study. However, inconsistent 

results for quality-control samples collected and analyzed 

using this analytical method suggested that the results were 

unreliable. Therefore, the data collected for this group of 

analytes are not presented in this report.

 Pharmaceutical compounds targeted for analysis 

in this study include 10 prescription and over-thecounter medications, dehydronifedipine (an antianginal 

metabolite), cotinine (a nicotine metabolite), caffeine, and 

1,7-dimethylxanthine (a caffeine metabolite) (table 3D). 

GAMA protocols call for censoring pharmaceutical data 

more rigorously than the other data because of the newness 

of the analytical method. Concentrations of pharmaceutical 

compounds that were less than their respective long-term 

method detection levels (LT-MDL) were considered nondetections for this study. Four pharmaceutical compounds 

were detected in USAW samples at concentrations greater 

than these censoring levels (table 7-LT-MDLs are equal to half 

the LRLs). These included two medications (acetaminophen 

and carbamazepine), caffeine, and the caffeine metabolite, 

1,7-dimethylxanthine. 

No pharmaceutical compound was detected in more 

than five wells, and all of the concentrations were low. 

Health-based thresholds do not exist for concentrations 

of pharmaceuticals in drinking water. However, to reach 

concentrations of the two detected medications equal to 

dosages typically recommended or prescribed would, in all 

cases, require consuming more than one million liters of the 

sampled water. The sampled concentrations of caffeine and 

its metabolite were, in all cases, less than one-millionth of the 

concentration of caffeine in regular coffee.

Constituents of Special Interest

Perchlorate, 1,2,3-trichloropropane (1,2,3-TCP), 

1,4-dioxane, and NDMA are constituents of special interest 

in California because they recently have been found in, or 

may reach, water supplies (California Department of Public 

Health, 2007b). These four compounds were analyzed by 

the Montgomery Watson-Harza Laboratory. Table 8 includes 

all four of these constituents, even though 1,4-dioxane was 

not detected in USAW ground water and both detections of 

NDMA were V-coded. A result is V-coded when the analyte 

is detected in a sample and an associated blank; thus the 

result is suspect and is not included in ground-water quality 

assessment. Perchlorate was detected in two-thirds of the grid 

wells, and 11 grid wells had perchlorate concentrations greater 

than or equal to the MCL-CA of 6 μg/L (table 8). 

1,2,3-TCP is a compound that was measured by more 

than one analytical method. NWQL used the VOC analytical 

method (lab schedule 2020) to analyze all USAW samples for 

1,2,3-TCP; results are described above and listed in table 5. 

By the VOC method, 1,2,3-TCP was not detected in any 

samples at a laboratory reporting level (LRL) of 0.12 μg/L. 

Samples from the 32 wells on the “slow” schedule were 

additionally analyzed for 1,2,3-TCP at the much lower LRL 

of 0.005 by Montgomery Watson-Harza Laboratory. By this 

“preferred” method, 1,2,3-TCP was detected in samples from 

three grid wells at concentrations far below its HAL-US 

(table 8). Samples from wells on the “slow” schedule were 

also analyzed for 1,4-dioxane and NDMA. 1,4-dioxane was 

not detected, and NDMA was detected in samples from two 

wells at concentrations less than those detected in two out 

of three USAW field blanks (table A3). Those detections 

were, therefore, not included in this ground-water quality 

assessment.

Dissolved organic carbon (DOC) is an additional organic 

analyte that was sampled in 36 USAW grid wells, and it 

was detected in 25 of these wells. However, DOC was also 

detected in two out of three blanks (table A3), resulting in 

the the V-coding of all but one of the USAW ground-water 

detections of DOC (table 9).
14 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Inorganic Constituents

Unlike the organic constituents and the constituents 

of special interest, most of the inorganic constituents 

are naturally present in ground water, although their 

concentrations may be influenced by human activities.

The nutrients, nitrogen and phosphorus, and the dissolved 

organic carbon in ground water can affect biological activity in 

aquifers and in surface water bodies that receive ground-water 

discharge. Nitrogen may be present in the form of ammonia, 

nitrite, or nitrate, depending on the oxidation-reduction 

state of the ground water. High concentrations of nitrate can 

adversely affect human health, particularly the health of 

infants. Samples from 49 USAW grid wells were analyzed for 

nutrients (table 9). Samples from eight understanding wells 

also were analyzed for nutrients. Concentrations of nitrite plus 

nitrate in samples from 14 grid wells were greater than the 

MCL-US. A well sampled for additional understanding also 

had nitrite plus nitrate greater than this MCL. Concentrations 

of the other forms of nitrogen were less than their health-based 

thresholds in all samples. There is no health-based threshold 

for phosphorus concentrations in drinking water. 

The major-ion composition, total dissolved solids (TDS) 

content, and levels of certain trace elements in ground water 

affect the aesthetic properties of water, such as taste, color, and 

odor, and the technical properties, such as scaling and staining. 

CDPH has established non-enforceable thresholds (SMCLCAs) that are based on aesthetic and technical properties rather 

than health-based concerns for the major ions, such as chloride 

and sulfate, TDS, turbidity, and several trace elements. 

 Samples from 49 USAW grid wells were analyzed for 

major ions and trace elements. Samples from eight wells 

sampled for additional understanding were also analyzed for 

these compounds. Chloride concentrations were greater than 

the recommended SMCL-CA of 250 mg/L in samples from 

three USAW grid wells, and one of these concentrations was 

also above the upper SMCL-CA of 500 mg/L (table 10). The 

sulfate concentration was greater than the recommended 

SMCL-CA of 250 mg/L in the sample from one grid well. 

Nineteen samples from USAW grid wells contained TDS 

concentrations above the recommended SMCL-CA of 

500 mg/L, and three of these concentrations were also above 

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

Iron and manganese are trace elements whose 

concentrations are affected by the oxidation-reduction state 

of the ground water. Precipitation of minerals containing 

iron or manganese may cause orange or black staining of 

surfaces. Concentrations of manganese in USAW wells 

were typically less than 10 μg/L (table 11). However, two 

grid wells had concentrations greater than the SMCL-CA of 

50 μg/L. Similarly, concentrations of iron were typically less 

than100 μg/L, but one grid well had a concentration greater 

than the SMCL-CA of 300 μg/L. 

USAW samples were analyzed for twenty-five different 

trace elements. All of these trace elements were detected at 

least once except for beryllium. Eighteen of the twenty-five 

trace elements have health-based thresholds. In addition, the 

major ion fluoride has a health-based threshold, All fluoride 

concentrations in USAW samples were below its healthbased threshold, as were concentrations of all trace elements 

except arsenic, boron, molybdenum, and vanadium, (table 11). 

Samples from two grid wells and a well for additional 

understanding had arsenic concentrations above the MCL-US 

of 10 μg/L. One grid well sample contained boron above 

the NL-CA of 1,000 μg/L. Two grid well samples contained 

molybdenum above the HAL-US of 40 μg/L. One grid 

well, and one well for additional understanding, contained 

vanadium above the NL-CA of 50 μg/L.

Seven trace elements were detected in at least one USAW 

field blank, sometimes resulting in V-coding of the sample 

results for these compounds in the ground-water samples. 

Results in table 11 that are qualified (coded) with a “V” may 

have been affected by inadvertent sample contamination, and 

were not counted as sample detections for the ground-water 

quality assessment.

The relative proportions of arsenic, iron, and chromium 

species depend on the oxidation-reduction state of the ground 

water. The oxidized and reduced species have different 

solubilities in ground water and may have different effects on 

human health. The relative proportions of the oxidized and 

reduced species of each element also are used to help interpret 

the oxidation-reduction of the aquifer. The relative proportions 

of the other species can be calculated by finding the difference. 

Samples from the 32 “slow” wells were analyzed for the 

oxidation-reduction species of arsenic, iron, and chromium. 

Concentrations of total arsenic, iron, and chromium, and 

concentrations of either the reduced or the oxidized species 

of each element are reported on table 12. Analyses of the 

iron detected in USAW samples indicated both oxidized and 

reduced species, but slightly more reduced species, Fe(II). 

In contrast, analyses of arsenic and chromium indicated 

more oxidized species, As(V) and Cr(VI), respectively, than 

reduced; indeed, arsenic was entirely in the oxidized form 

in all 18 samples in which it was detected. Concentrations 

of total arsenic, iron, and chromium analyzed at the USGS 

Trace Metal Laboratory (table 12) were generally similar to 

those analyzed at USGS NWQL (table 11). Minor differences 

could be due to the different analytical methods (Appendix

table A1); concentrations reported on table 11 are considered 

to be more accurate.
Water-Quality Results 15

Isotopic Tracer Constituents

Isotopic ratios, which include the ratios of stable oxygen 

isotopes and hydrogen isotopes in water, of stable nitrogen 

isotopes in dissolved nitrogen gas, and stable nitrogen 

isotopes and oxygen isotopes in dissolved nitrate, along with 

the tritium and carbon-14 activities in ground water, may be 

used as tracers of hydrologic processes. In USAW samples, 

hydrogen-2/hydrogen-1 ratios (δ2H) ranged from -70.2 to 

-45.9 per mil, and oxygen-18/oxygen-16 ratios (δ18O) ranged 

from -10.17 to -5.33 per mil (table 13).

 The isotopic ratios of nitrogen isotopes in dissolved 

nitrogen gas, and nitrogen isotopes and oxygen isotopes in 

dissolved nitrate (table 13) can be used to help determine 

the source of nitrate in ground water and to indicate which 

processes affect dissolved nitrate concentrations. In USAW 

samples, the nitrogen-15/nitrogen-14 ratios in the dissolved 

nitrate fraction ranged from 1 to 21 per mil, and the 

oxygen-18/oxygen-16 ratios ranged from 0.31 to 10.10 per 

mil. The nitrogen-15/nitrogen-14 ratios in the dissolved gas 

fraction ranged from 0.15 to 3.12 per mil.

Tritium and carbon-14 activities (table 13), and helium 

isotope ratios (table 15) can provide information about the 

ages of the ground-water. Tritium is a radioactive isotope of 

hydrogen that is incorporated into the water molecule. Low 

levels of tritium are continuously produced by cosmic-ray 

bombardment of water in the atmosphere, and a large amount 

of tritium was produced by atmospheric testing of nuclear 

weapons between 1952 and 1963. Thus, activities of tritium 

in water above background levels generally indicate that the 

water was recharged since the early 1950s (Izbicki, 1996). 

Of the inorganic tracer constituents analyzed for this study, 

tritium is the only one that has a health-based threshold. 

Although tritium was detected in 28 of the 32 USAW samples 

for which it was analyzed, measured tritium activities in 

all these samples were less than one one-thousandth of the 

MCL-CA (table 13). 

Helium isotope ratios (table 15) can be used with tritium 

concentrations to estimate more exact ages for young ground 

water. Carbon-14 (table 13) is a radioactive isotope of carbon 

that is incorporated into dissolved carbonate species in 

water. Low levels of carbon-14 are continuously produced 

by cosmic-ray bombardment of nitrogen in the atmosphere. 

Because carbon-14 has a half-life of approximately 

5,700 years, low activities of carbon-14 relative to modern 

values generally indicate the presence of ground water that is 

several thousand years old (Kalin, 2000). Carbon-14 activities 

in most USAW samples indicated that they contained greater 

than 70 percent modern carbon.

Dissolved Standard and Noble Gases

Dissolved-gas data (table 14) are used to define recharge 

temperatures used for age-dating, to indicate microbial 

processes, such as denitrification, and to trace sources of 

ground-water recharge. Dissolved nitrogen, argon, oxygen and 

carbon dioxide were detected at various concentrations in all 

samples analyzed for standard dissolved gases. In contrast, 

dissolved methane was detected in only 16 percent of the 

samples. Several dissolved-gas samples were compromised 

because the laboratory observed gas bubbles in the samples 

bottles prior to analysis. These compromised samples are 

identified in table 14. Noble-gas concentrations (table 15) 

can be used to help interpret ground-water recharge sources 

because the concentrations of the different noble gases depend 

on water temperature. Such interpretation is beyond the scope 

of this report and will be presented in a future report.

Radioactive Constituents

Radioactivity is the release of energy or energetic 

particles during changes in the structure of the nucleus of 

an atom. The source of most of the radioactivity in ground 

water is decay of naturally-occurring isotopes of uranium and 

thorium in minerals that are 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. Radium-226, 

radium-228, and radon-222 are radioactive isotopes formed 

during the uranium and thorium decay series. In each step in 

the decay series, one radioactive element turns into a different 

radioactive element by emitting an alpha particle (helium-4 

nucleus) or a beta particle (electron or positron) from its 

nucleus. For example, radium-226 emits an alpha particle 

and transforms into radon-222. Radium-228 decays to form 

actinium-228 by emission of a beta particle. The alpha and 

beta particles emitted during radioactive decay are hazardous 

to human health because these energetic particles may damage 

cells. Radiation damage to cell DNA increases the risk of 

cancer.

Activity is often used instead of concentration for 

reporting the presence of radioactive constituents. Activity of 

radioactive constituents in ground water is measured in units 

of picocuries per liter (pCi/L); one picocurie approximately 

equals two atoms decaying per minute. The number of atoms 

decaying is equal to the number of alpha or beta particles 

emitted. 
16 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

 The 32 USAW samples analyzed for radioactive 

constituents had activities of radium, gross alpha (except one 

gross-alpha measurement at 17.3 pCi/L-72-hour count) and 

beta emitters less than established health-based standards 

(table 16). In contrast, activities of radon-222 in samples 

from more than half of these wells were above the proposed 

MCL-US of 300 pCi/L, although none had activities above the 

proposed alternative MCL-US of 4,000 pCi/L. The alternative 

MCL-US will apply if the State or local water agency has an 

approved multimedia mitigation program to address radon in 

indoor air (U.S. Environmental Protection Agency, 1999a).

Microbial Indicators

Water is disinfected during drinking-water treatment to 

prevent diseases that may be spread by water-borne microbial 

constituents derived from human or animal wastes. The 

specific viruses and bacteria responsible for diseases generally 

are not measured because routine analytical methods are not 

available. Measurements are made of microbial constituents 

that are more easily analyzed and serve as indicators of human 

or animal waste in water. Drinking-water purveyors respond 

to detections of microbial indicators by applying additional 

disinfection agents to the water.

The thirty-two samples from the USAW “slow” wells 

were analyzed for microbial indicators. No samples contained 

the viral indicators F-specific and somatic coliphage, and none 

contained the bacterial indicator Escherichia coli (E. coli). 

However, the bacterial indicator, total coliforms (table 17), 

was detected once. The threshold for total coliforms is based 

on recurring detections; thus, the detection reported here does 

not constitute an exceedance of the MCL-US. 

Future Work

The data presented in this report will be evaluated as 

part of the ongoing Priority Basin Project using statistical, 

qualitative, and quantitative approaches to assess the natural 

and human factors affecting ground-water quality. Waterquality data contained in the CDPH and USGS NWIS 

databases, and water-quality data available from other State 

and local water agencies will be compiled, evaluated, and used 

to complement the data presented in this report; the results of 

these efforts will be presented in future publications.

Summary 

Ground-water quality in the approximately 1,000 squaremile Upper Santa Ana Watershed (USAW) was investigated 

from November 2006 through March 2007 as part of the 

Priority Basin Project of Groundwater Ambient Monitoring 

and Assessment (GAMA) Program. The project is a 

comprehensive assessment of statewide ground-water quality 

designed to identify and characterize risks to ground-water 

resources, and to increase the amount of information about 

ground-water quality available to the public. Ground-water 

samples were analyzed for nearly 400 constituents, including 

volatile organic compounds, pesticides and pesticide 

degradates, pharmaceutical compounds, potential wastewaterindicator compounds, nutrients, major and minor ions, trace 

elements, radioactivity, and microbial indicators. Naturally 

occurring isotopes (stable isotopes of hydrogen, oxygen, 

nitrogen, and carbon, and activities of tritium and carbon-14) 

and dissolved gases also were measured to help interpret the 

source and age of the sampled ground water. Quality-control 

samples (blanks, replicates, or samples for matrix spikes) were 

collected at 20 percent of the wells, and the results for these 

samples were used to evaluate the quality of the data derived 

from the ground-water samples. 

This study did not attempt to evaluate the quality of water 

delivered to consumers; after withdrawal from the ground, 

water typically is treated, disinfected, and blended with other 

waters to maintain acceptable water quality. Regulatory 

thresholds apply to treated water that is served to the 

consumer, not to raw ground water. However, to provide some 

context for the results, concentrations of constituents measured 

in the raw ground water were compared with health-based 

thresholds established by the U.S. Environmental Protection 

Agency (USEPA) and the California Department of Public 

Health (CDPH). 

In this study, 14 constituents were detected 

at concentrations higher than regulatory and nonregulatory health-based thresholds: carbon tetrachloride 

(tetrachloromethane), dibromochloropropane (DBCP), 1,1 

dichloroethene, tetrachloroethene (PCE), trichloroethene 

(TCE), nitrate, arsenic, boron, molybdenum, vanadium, 

perchlorate, radon-222, gross-alpha, and total coliforms. 

These constituents were detected in 37 of the 90 grid wells 

and in 2 of the 9 understanding wells. However, 12 of the 37 

grid wells with concentrations above health-based thresholds 

only had such concentrations for radon-222. Radon-222 

has a proposed MCL-US of 300 pCi/L, and an alternative 

proposed MCL-US of 4,000 pCi/L that will apply if the State 

or local water agency has an approved multimedia mitigation 

program to address radon in indoor air (U.S. Environmental 

Protection Agency, 1999a). While some radon-222 activities 

in USAW samples exceeded the lower proposed MCL-US, 

no activities were as high as the upper proposed MCL-US. 

Seven additional constituents (total dissolved solids, chloride, 

sulfate, specific conductance, pH, iron, and manganese) were 

detected at concentrations above thresholds set for aesthetic 

concerns. These constituents were detected in 32 of the grid 

wells and 1 understanding well. Future work will evaluate 

the data presented in this report using statistical, qualitative, 

and quantitative approaches to assess the natural and human 

factors affecting ground-water quality.
References Cited 17

Acknowledgments

The authors thank the following cooperators for their 

support: the California State Water Resources Control 

Board (SWRCB), California Department of Public Health 

(CDPH), California Department of Water Resources (DWR), 

and Lawrence Livermore National Laboratory (LLNL). 

We especially thank the cooperating well owners and water 

purveyors for their generosity in allowing the USGS to collect 

samples from their wells. Steven Mains of Water Master 

Support Services, San Bernardino Valley Municipal Water 

District, and Wildermuth Environmental Incorporated also 

aided us in accessing wells for sampling. Two reviewers, 

Jan Stepek (SWRCB) and Peter Dileanis (USGS), provided 

comments to improve this work. Funding for this work 

was provided by California State bonds authorized by 

Proposition 50 and administered by the SWRCB.

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Table 1 23

GAMA well

identification 

number

Sampling information Construction information

(ft below LSD)

Date Schedule

Elevation of LSD 

(ft above 

NAVD88)

Well 

depth 

Top 

perforation

Bottom 

perforation 

Grid wells

USAWB-01 11-27-06 Fast 1,075 1,067 497 1,047

USAWB-02 11-27-06 Slow 1,857 234 61 230

USAWB-03 11-28-06 Fast 2,310 199 45 175

USAWB-04 11-28-06 Slow 1,422 900 464 884

USAWB-05 11-28-06 Fast 2,042 50 21 48

USAWB-06 11-28-06 Fast 1,633 400 177 400

USAWB-07 11-29-06 Slow 1,005 654 240 462

USAWB-08 12-11-06 Slow 1,188 580 126 560

USAWB-09 12-11-06 Fast 3,075 126 52 126

USAWB-10 12-12-06 Slow 1,137 708 490 680

USAWB-11 12-13-06 Slow 1,249 606 378 569

USAWB-12 12-13-06 Fast 1,333 950 500 930

USAWB-13 12-14-06 Fast 1,313 474 150 442

USAWB-14 12-14-06 Slow 1,418 1,060 300 1,040

USAWB-15 12-14-06 Fast 1,323 1,020 600 1,000

USAWB-16 01-08-07 Intermediate 1,032 963 888 951

USAWB-17 01-10-07 Fast 1,155 421 173 415

USAWB-18 01-11-07 Intermediate 1,102 534 244 534

USAWB-19 01-11-07 Fast 1,763 na na na

USAWC-01 01-29-07 Intermediate 1,078 795 na na

USAWC-02 01-29-07 Intermediate 1,173 940 na na

USAWC-03 01-29-07 Fast 1,412 1,040 500 1,030

USAWC-04 01-30-07 Slow 859 560 317 535

USAWC-05 01-30-07 Fast 820 800 300 775

USAWC-06 01-30-07 Fast 1,008 903 472 849

USAWC-07 01-31-07 Fast 670 218 113 213

USAWC-08 01-31-07 Slow 782 370 210 370

USAWC-09 01-31-07 Fast 603 na na na

USAWC-10 02-01-07 Fast 625 520 290 500

USAWC-11 02-01-07 Slow 747 350 200 350

USAWC-12 02-01-07 Intermediate 634 na na na

USAWC-13 02-12-07 Fast 968 na na na

USAWC-14 02-12-07 Slow 960 1,028 415 1,007

USAWC-15 02-12-07 Fast 907 702 406 635

USAWC-16 02-13-07 Fast 1,843 491 230 460

USAWC-17 02-13-07 Slow 984 900 370 885

USAWC-18 02-13-07 Fast 1,453 764 322 702

USAWC-19 02-13-07 Fast 3,663 Spring Spring Spring

USAWC-20 02-14-07 Intermediate 1,248 918 na na

USAWC-21 02-14-07 Slow 1,633 1,110 400 1,090

USAWC-22 02-14-07 Fast 1,026 na na na

USAWC-23 02-15-07 Slow 634 1,180 440 1,180

USAWC-24 02-15-07 Topical1 842 300 280 300

USAWC-25 03-28-07 Intermediate 774 435 230 430

USAWE-01 12-04-06 Slow 1,267 1,430 420 1,410

USAWE-02 12-05-06 Slow 1,247 1,720 380 1,700

USAWE-03 12-06-06 Slow 1,313 980 570 980

USAWE-04 12-07-06 Slow 1,258 740 300 730

USAWR-01 11-29-06 Fast 879 na na na

USAWR-02 11-29-06 Fast 822 613 284 600

USAWR-03 11-30-06 Slow 762 na 24 170

Table 1. Identification, sampling, and construction information for wells sampled for the Upper Santa Ana Watershed Groundwater 

Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo. USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. Sampling schedule: Sampling schedules are described in table 2. Elevation of landsurface datum (LSD) is a datum plane that is approximately at land surface at each well. The elevation of the LSD is described in feet above the North American 

Vertical Datum of 1988 (NAVD 88). Abbreviations: ft, foot; LSD, land surface datum; na, not available]
24 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

GAMA well

identification 

number

Sampling information Construction information

(ft below LSD)

Date Schedule

Elevation of LSD 

(ft above 

NAVD88)

Well 

depth 

Top 

perforation

Bottom 

perforation 

USAWR-04 12-12-06 Fast 799 89 28 89

USAWR-05 12-12-06 Intermediate 868 192 na na

USAWR-06 01-09-07 Intermediate 807 190 120 180

USAWR-07 01-09-07 Intermediate 713 170 80 150

USAWR-08 01-10-07 Slow 898 402 40 380

USAWR-09 01-10-07 Intermediate 819 346 60 346

USAWR-10 01-10-07 Intermediate 643 220 108 204

USAWR-11 01-11-07 Slow 1,093 644 250 634

USAWR-12 01-29-07 Slow 733 515 200 250

USAWS-01 01-22-07 Fast 1,548 225 100 205

USAWS-02 01-22-07 Slow 1,474 518 104 518

USAWS-03 01-22-07 Fast 1,473 160 55 140

USAWS-04 01-22-07 Fast 1,496 150 50 150

USAWS-05 01-23-07 Intermediate 1,437 625 100 620

USAWS-06 01-23-07 Slow 1,533 650 200 650

USAWS-07 01-23-07 Fast 1,432 300 na na

USAWS-08 01-24-07 Slow 1,655 428 170 420

USAWS-09 01-24-07 Fast 1,453 370 140 350

USAWS-10 01-24-07 Fast 1,420 360 90 320

USAWS-11 01-25-07 Fast 1,431 380 80 340

USAWS-12 01-25-07 Slow 1,463 760 240 740

USAWS-13 01-25-07 Fast 1,426 410 230 390

USAWS-14 02-05-07 Slow 1,595 1,550 470 1,530

USAWS-15 02-06-07 Slow 1,572 328 na na

USAWS-16 02-06-07 Intermediate 1,450 na na na

USAWS-17 02-07-07 Fast 1,495 na na na

USAWS-18 02-07-07 Slow 1,595 714 324 714

USAWS-19 02-07-07 Fast 1,463 na na na

USAWS-20 02-08-07 Slow 1,567 696 300 676

USAWS-21 02-08-07 Intermediate 1,481 900 440 900

USAWY-01 11-27-06 Fast 2,496 350 300 315

USAWY-02 11-30-06 Fast 2,593 596 290 584

USAWY-03 12-13-06 Fast 2,093 600 150 576

USAWY-04 12-13-06 Intermediate 2,083 1,710 705 1,690

USAWY-05 01-08-07 Slow 2,444 585 320 585

USAWY-06 01-09-07 Slow 2,443 790 150 340

USAWY-07 01-11-07 Fast 2,881 314 164 314

USAWY-08 01-11-07 Fast 3,127 444 58 434

USAWY-09 01-24-07 Fast 2,636 946 320 694

Understanding wells

USAWU-01 11-29-06 Topical 784 170 50 170

USAWU-02 11-30-06 Topical 2,103 1,100 390 1,100

USAWU-03 12-11-06 Fast 4,882 220 180 220

USAWU-04 01-08-07 Intermediate 1,063 540 320 520

USAWU-05 01-08-07 Topical 1,293 na 310 787

USAWU-06 01-30-07 Topical1 905 800 295 784

USAWU-07 02-12-07 Topical 941 980 400 980

USAWU-08 02-15-07 Intermediate 635 na na na

USAWU-09 02-15-07 Topical1 804 310 290 310

1

Potential wastewater indicators and dissolved organic carbon were also analyzed for this well.

Table 1. Identification, sampling, and construction information for wells sampled for the Upper Santa Ana Watershed Groundwater 

Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo. USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. Sampling schedule: Sampling schedules are described in table 2. Elevation of landsurface datum (LSD) is a datum plane that is approximately at land surface at each well. The elevation of the LSD is described in feet above the North American 

Vertical Datum of 1988 (NAVD 88). Abbreviations: ft, foot; LSD, land surface datum; na, not available]
Table 2 25

Analyte classes

Table reference Sampling schedule

List Results Slow Intermediate Fast Topical

Water-quality indicators

DO, T, SC, pH 4 4 X X X X

Alkalinity1 4 4 X X1 X1

Turbidity 4 4 X

Organic constituents

DOC2 3G 9 X

VOC 3A 5 X X X X

Pesticides 3B, 3C 6 X X X

Pharmaceuticals 3D 7 X X X

Wastewater-indicators 3E na3 X X X

Constituents of special interest

Perchlorate 3F 8 X X X X

NDMA 3F 8 X

1,4-Dioxane 3F 8 X

1,2,3-TCP (low level) 3F 8 X

Chlorofluorocarbons (low level)4 na na X

Inorganic constituents

Nutrients 3G 9 X X X

Major, minor ions, trace elements5 3H 10, 11 X X X

Species of As, Cr and Fe 3I 12 X

Stable isotopes

δ2H and δ18O in water 3J 13 X X X X

δ15N and δ18O in nitrate 3J 13 X X X

δ15N in nitrogen gas 3J 13 X X X

δ13C and carbon-14 3J 13 X X X

Radioactivity and gases

Tritium6 3J 13 X na na na

Radium isotopes 3J 16 X

Radon-222 3J 16 X

Alpha and beta radiation 3J 16 X

Dissolved gases 3K 14 X X X

Noble gases 3K 15 X X X X

Microbial constituents

Coliforms and coliphages 3L 17 X

1

 Lab alkalinities only for intermediate and topical samples. Both field and lab alkalinities for Slow samples.

2

 DOC was added to 1 intermediate and 3 topical samples for 36 total analyses.

3

 Potential wastewater-indicator data are not presented in this report because of unsatisfactory quality-control data results.

4

 Low-level chlorofluorocarbon results not available for this report.

5

 Mercury analysis only done for Slow samples.

6

 Tritium by both Lawrence Livermore National Laboratory and USGS (Menlo Park) for Slow samples. Only USGS tritium data are available for this report.

Table 2. Classes of chemical and microbial constituents and water-quality indicators collected for the slow, intermediate, fast, and 

topical well sampling schedules in the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, 

California, November 2006 to March 2007.

[X indicates that analyte or analyte class was sampled for that schedule, blank cell indicates that analyte or analyte class was not sampled for that schedule. 

Abbreviations: na, samples were collected, but data are not available for this report; DO, dissolved oxygen; T, temperature; SC, specific conductance; DOC, 

dissolved organic carbon; VOC, volatile organic compound; NDMA; N-nitrosodimethylamine; TCP, trichloropropane; As, arsenic; Cr, chromium; Fe. iron; δ2H, 

delta deuterium; δ18O, delta oxygen-18; δ15N, delta nitrogen-15; δ13C, delta carbon-13; LLNL, Lawrence Livermore National Laboratory]
26 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Constituent Primary use 

or source

USGS 

parameter 

code

CAS 

number

 LRL 

(μg/L)

Threshold 

type

Threshold 

value 

(μg/L)

Detection

Acetone Solvent 81552 67-64-1 6 na na –

Acrylonitrile Organic synthesis 34215 107-13-1 0.4 RSD5-US 0.6 –

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-US1 80 D

Bromoform (Tribromomethane) Disinfection by-product (THM) 32104 75-25-2 0.08 MCL-US1 80 D

2-Butanone (MEK, Methyl ethyl ketone) Solvent 81595 78-93-3 1.6 HAL-US 4,000 –

n-Butylbenzene Gasoline hydrocarbon 77342 104-51-8 0.14 NL-CA 260 –

sec-Butylbenzene Gasoline hydrocarbon 77350 135-98-8 0.04 NL-CA 260 –

tert-Butylbenzene Gasoline hydrocarbon 77353 98-06-6 0.08 NL-CA 260 –

Carbon disulfide Organic synthesis 77041 75-15-0 0.06 NL-CA 160 –

Carbon tetrachloride (Tetrachloromethane) Solvent 32102 56-23-5 0.08 MCL-CA 0.5 D

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 0.08 MCL-US1 80 D

Chloromethane Refrigerant/organic synthesis 34418 74-87-3 0.10 HAL-US 30 D

3-Chloro-1-propene Organic synthesis 78109 107-05-1 0.08 na na –

2-Chlorotoluene Solvent 77275 95-49-8 0.04 NL-CA 140 –

4-Chlorotoluene Solvent 77277 106-43-4 0.04 NL-CA 140 –

Dibromochloromethane Disinfection by-product (THM) 32105 124-48-1 0.12 MCL-US1 80 D

1,2-Dibromo-3-chloropropane (DBCP) Fumigant 82625 96-12-8 0.5 MCL-US 0.2 D

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 –

1,2-Dichlorobenzene Solvent 34536 95-50-1 0.04 MCL-CA 600 D

1,3-Dichlorobenzene Solvent 34566 541-73-1 0.04 HAL-US 600 –

1,4-Dichlorobenzene Fumigant 34571 106-46-7 0.04 MCL-CA 5 D

trans-1,4-Dichloro-2-butene Organic synthesis 73547 110-57-6 0.6 na na –

Dichlorodifluoromethane (CFC-12) Refrigerant 34668 75-71-8 0.14 NL-CA 1,000 D

1,1-Dichloroethane Solvent 34496 75-34-3 0.06 MCL-CA 5 D

1,2-Dichloroethane Solvent 32103 107-06-2 0.10 MCL-CA 0.5 D

1,1-Dichloroethene (DCE) Organic synthesis 34501 75-35-4 0.02 MCL-CA 6 D

cis-1,2-Dichloroethene Solvent 77093 156-59-2 0.02 MCL-CA 6 D

trans-1,2-Dichloroethene Solvent 34546 156-60-5 0.018 MCL-CA 10 D

Dichloromethane (Methylene chloride) Solvent 34423 75-09-2 0.04 MCL-US 5 D

1,2-Dichloropropane Fumigant 34541 78-87-5 0.02 MCL-US 5 D

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

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

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

cis-1,3-Dichloropropene Fumigant 34704 10061-01-5 0.06 RSD5-US2 4 –

trans-1,3-Dichloropropene Fumigant 34699 10061-02-6 0.10 RSD5-US2 4 –

Diethyl ether Solvent 81576 60-29-7 0.08 na na –

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

Ethylbenzene Gasoline hydrocarbon 34371 100-41-4 0.02 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 –

1-Ethyl-2-methylbenzene (o-Ethyl toluene) Gasoline hydrocarbon 77220 611-14-3 0.04 na na –

Table 3A. Volatile organic compounds, primary uses or sources, comparative thresholds, and reporting information for the U.S. 

Geological Survey National Water Quality Laboratory schedule 2020.

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. CAS number: This report contains 

CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through CAS Client 

ServicesSM. Threshold type: 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. Abbreviations: CAS, Chemical Abstract Service; LRL, laboratory reporting level; 

HAL-US, U.S. Environmental Protection Agency Lifetime Health Advisory; MCL-CA, California Department of Public Health maximum contaminant level; 

MCL-US, U.S. Environmental Protection Agency maximum contaminant level; NL-CA, California Department of Public Health notification level; RSD5-US, 

U.S. Environmental Protection Agency risk specific dose at a risk factor of 10-5; D, detected; na, not available; μg/L, micrograms per liter; –, not detected; THM, 

trihalomethane]
Table 3A 27

Table 3A. Volatile organic compounds, primary uses or sources, comparative thresholds, and reporting information for the U.S. 

Geological Survey National Water Quality Laboratory schedule 2020.—Continued

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. CAS number: This report contains 

CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through CAS Client 

ServicesSM. Threshold type: 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. Abbreviations: CAS, Chemical Abstract Service; LRL, laboratory reporting level; 

HAL-US, U.S. Environmental Protection Agency Lifetime Health Advisory; MCL-CA, California Department of Public Health maximum contaminant level; 

MCL-US, U.S. Environmental Protection Agency maximum contaminant level; NL-CA, California Department of Public Health notification level; RSD5-US, 

U.S. Environmental Protection Agency risk specific dose at a risk factor of 10-5; D, detected; na, not available; μg/L, micrograms per liter; –, not detected; THM, 

trihalomethane]

Constituent Primary use 

or source

USGS 

parameter 

code

CAS 

number

 LRL 

(μg/L)

Threshold 

type

Threshold 

value 

(μg/L)

Detection

Hexachlorobutadiene Organic synthesis 39702 87-68-3 0.10 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 0.4 na na –

Isopropylbenzene (Cumene) Gasoline hydrocarbon 77223 98-82-8 0.04 NL-CA 770 –

4-Isopropyl-1-methylbenzene Gasoline hydrocarbon 77356 99-87-6 0.08 na na –

Methyl acrylate Organic synthesis 49991 96-33-3 0.4 na na –

Methyl acrylonitrile Organic synthesis 81593 126-98-7 0.40 na na –

Methyl bromide (Bromomethane) Fumigant 34413 74-83-9 0.4 HAL-US 10 –

Methyl tert-butyl ether (MTBE) Gasoline oxygenate 78032 1634-04-4 0.10 MCL-CA 13 D

Methyl iodide (Iodomethane) Organic synthesis 77424 74-88-4 0.4 na na –

Methyl methacrylate Organic synthesis 81597 80-62-6 0.20 na na –

4-Methyl-2-pentanone (MIBK, isobutyl 

methyl ketone)

Solvent 78133 108-10-1 0.2 NL-CA 120 –

Methyl tert-pentyl ether (tert-Amyl methyl 

ether, TAME)

Gasoline oxygenate 50005 994-05-8 0.04 na na –

Naphthalene Gasoline hydrocarbon 34696 91-20-3 0.4 NL-CA 17 –

n-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 –

Tetrachloroethene (PCE) Solvent 34475 127-18-4 0.04 MCL-US 5 D

Tetrahydrofuran Solvent 81607 109-99-9 1.0 na na –

1,2,3,4-Tetramethylbenzene (Prehnitene) Gasoline hydrocarbon 49999 488-23-3 0.14 na na –

1,2,3,5-Tetramethylbenzene (Isodurene) Gasoline hydrocarbon 50000 527-53-7 0.12 na na –

Toluene Gasoline hydrocarbon 34010 108-88-3 0.018 MCL-CA 150 D3

1,2,3-Trichlorobenzene Organic synthesis 77613 87-61-6 0.12 na na –

1,2,4-Trichlorobenzene Solvent 34551 120-82-1 0.12 MCL-CA 5 –

1,1,1-Trichloroethane (TCA) Solvent 34506 71-55-6 0.04 MCL-CA 200 D

1,1,2-Trichloroethane Solvent 34511 79-00-5 0.04 MCL-CA 5 –

Trichloroethene (TCE) Solvent 39180 79-01-6 0.02 MCL-US 5 D

Trichlorofluoromethane (CFC-11) Refrigerant 34488 75-69-4 0.08 MCL-CA 150 D

1,2,3-Trichloropropane (1,2,3-TCP) Solvent/organic synthesis 77443 96-18-4 0.12 HAL-US 40 –

1,1,2-Trichloro-1,2,2-trifluoroethane 

(CFC-113)

Refrigerant 77652 76-13-1 0.04 MCL-CA 1,200 D

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 D

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 –

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

106-42-3

0.08 MCL-CA4 1,750 –

o-Xylene Gasoline hydrocarbon 77135 95-47-6 0.04 MCL-CA4 1,750 –

1

 The MCL-US, and MCL-CA thresholds for trihalomethanes are the sum of chloroform, bromoform, bromodichloromethane, and dibromochloromethane.

2

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

3

 Toluene detections were at approximately the same concentrations as detections in blank samples. Detections in ground-water samples could be entirely 

attributed to unintended sample contamination.

4

 The MCL-CA threshold for xylenes is the sum of the m, p, and o isomers.
28 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Constituent Primary use 

or source

USGS 

parameter 

code

CAS 

number

 LRL 

(μg/L)

Threshold 

type

Threshold 

value 

(μg/L)

Detection

Acetochlor Herbicide 49260 34256-82-1 0.006 na na –

Alachlor Herbicide 46342 15972-60-8 0.005 MCL-US 2 –

Atrazine Herbicide 39632 1912-24-9 0.007 MCL-CA 1 D

Azinphos-methyl Insecticide 82686 86-50-0 0.08 na na –

Azinphos-methyl-oxon Degradate 61635 961-22-8 0.042 na na –1

Benfluralin Herbicide 82673 1861-40-1 0.01 na na –1

Carbaryl Insecticide 82680 63-25-2 0.06 RSD5-US 400 –

Carbofuran Insecticide 82674 1563-66-2 0.02 MCL-CA 18 –

2-Chloro-2,6-diethylacetanilide Degradate 61618 6967-29-9 0.0065 na na –

4-Chloro-2-methylphenol Degradate 61633 1570-64-5 0.005 na na –1

Chlorpyrifos Insecticide 38933 2921-88-2 0.005 HAL-US 20 –

Chlorpyrifos, oxygen analog Degradate 61636 5598-15-2 0.0562 na na –1

Cyanazine Herbicide 04041 21725-46-2 0.018 HAL-US 1 –

Cyfluthrin Insecticide 61585 68359-37-5 0.053 na na –1

λ-Cyhalothrin Insecticide 61595 91465-08-6 0.014 na na –1

Cypermethrin Insecticide 61586 52315-07-8 0.046 na na –1

DCPA (Dacthal) Herbicide 82682 1861-32-1 0.003 HAL-US 70 D

Deethylatrazine (2-Chloro-4-

isopropylamino-6-amino-s-triazine)

Degradate 04040 6190-65-4 0.014 na na D1

Desulfinylfipronil Degradate 62170 na 0.012 na na –2

Desulfinylfipronil amide Degradate 62169 na 0.029 na na –2

Diazinon Insecticide 39572 333-41-5 0.005 HAL-US 0.6 –

Diazinon oxon Degradate 61638 962-59-3 0.006 na na –

3,4-Dichloroaniline Degradate 61625 95-76-1 0.0045 na na D

3,5-Dichloroaniline Degradate 61627 626-43-7 0.012 na na –

Dichlorvos Insecticide 38775 62-73-7 0.013 na na –1

Dicrotophos Insecticide 38454 141-66-2 0.0843 na na –1

Dieldrin Insecticide 39381 60-57-1 0.009 RSD5-US 0.02 –

2,6-Diethylaniline Degradate 82660 579-66-8 0.006 na na –

Dimethoate Insecticide 82662 60-51-5 0.0061 na na –1

Disulfoton Insecticide 82677 298-04-4 0.02 HAL-US 0.7 –1

Disulfoton sulfone Degradate 61640 2497-06-5 0.014 na na –

α-Endosulfan Insecticide 34362 959-98-8 0.011 na na –

Endosulfan sulfate Degradate 61590 1031-07-8 0.022 na na –

EPTC Herbicide 82668 759-94-4 0.002 na na –

Ethion Insecticide 82346 563-12-2 0.016 na na –

Ethion monoxon Degradate 61644 17356-42-2 0.021 na na –

Ethoprophos Herbicide 82672 13194-48-4 0.012 na na –

2-Ethyl-6-methylaniline Degradate 61620 24549-06-2 0.01 na na –

Fenamiphos Insecticide 61591 22224-92-6 0.029 HAL-US 0.7 –

Fenamiphos sulfone Degradate 61645 31972-44-8 0.053 na na –1

Fenamiphos sulfoxide Degradate 61646 31972-43-7 0.04 na na –1

Fipronil Insecticide 62166 120068-37-3 0.016 na na –2

Fipronil sulfide Degradate 62167 120067-83-6 0.013 na na –2

Table 3B. Pesticides and pesticide degradates, primary uses or sources, comparative thresholds, and reporting information for the 

U.S. Geological Survey National Water Quality Laboratory schedule 2033.

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. CAS number: This report contains 

CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through CAS Client 

ServicesSM . Threshold type: 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.Abbreviations: CAS, Chemical Abstract Service; LRL, laboratory reporting level; 

HAL-US, U.S. Environmental Protection Agency Lifetime Health Advisory; MCL-CA, California Department of Public Health maximum contaminant level; 

MCL-US, U.S. Environmental Protection Agency maximum contaminant level; RSD5-US, U.S. Environmental Protection Agency risk specific dose at a risk 

factor of 10-5; D, detected; na, not available; μg/L, micrograms per liter; –, not detected; LT-MDL, long-term method detection limit]
Table 3B 29

Constituent Primary use 

or source

USGS 

parameter 

code

CAS 

number

 LRL 

(μg/L)

Threshold 

type

Threshold 

value 

(μg/L)

Detection

Fipronil sulfone Degradate 62168 120068-36-2 0.024 na na –1

Fonofos Insecticide 04095 944-22-9 0.006 HAL-US 10 –

Hexazinone Herbicide 04025 51235-04-2 0.026 HAL-US 400 –1

Iprodione Fungicide 61593 36734-19-7 0.026 na na –

Isofenphos Insecticide 61594 25311-71-1 0.011 na na –

Malaoxon Degradate 61652 1634-78-2 0.039 na na –

Malathion Insecticide 39532 121-75-5 0.027 HAL-US 100 –

Metalaxyl Fungicide 61596 57837-19-1 0.0069 na na D

Methidathion Insecticide 61598 950-37-8 0.0087 na na –

Metolachlor Herbicide 39415 51218-45-2 0.010 HAL-US 700 –2

Metribuzin Herbicide 82630 21087-64-9 0.012 HAL-US 70 –

Molinate Herbicide 82671 2212-67-1 0.003 MCL-CA 20 –

Myclobutanil Fungicide 61599 88671-89-0 0.033 na na –

1-Naphthol Degradate 49295 90-15-3 0.0882 na na –1

Oxyfluorfen Herbicide 61600 42874-03-3 0.017 na na –1

Paraoxon-methyl Degradate 61664 950-35-6 0.019 na na –1

Parathion-methyl Insecticide 82667 298-00-0 0.008 HAL-US 1 –

Pendimethalin Herbicide 82683 40487-42-1 0.02 na na D

cis-Permethrin Insecticide 82687 54774-45-7 0.01 na na –1

Phorate Insecticide 82664 298-02-2 0.02 na na –

Phorate oxygen analog Degradate 61666 2600-69-3 0.027 na na –

Phosmet Insecticide 61601 732-11-6 0.0079 na na –1

Phosmet oxon Degradate 61668 3735-33-9 0.0511 na na –1

Prometon Herbicide 04037 1610-18-0 0.01 HAL-US 100 D

Prometryn Herbicide 04036 7287-19-6 0.0059 na na –

Pronamide Herbicide 82676 23950-58-5 0.004 na na –

Propanil Herbicide 82679 709-98-8 0.011 na na –

Propargite Insecticide 82685 2312-35-8 0.02 na na –1

cis-Propiconazole Fungicide 79846 60207-90-1 0.013 na na –1

trans-Propiconazole Fungicide 79847 60207-90-1 0.034 na na –1

Simazine Herbicide 04035 122-34-9 0.006 MCL-US 4 D

Tebuconazole Fungicide 62852 107534-96-3 0.0136 na na –1

Tebuthiuron Herbicide 82670 34014-18-1 0.016 HAL-US 500 D

Tefluthrin Insecticide 61606 79538-32-2 0.0033 na na –1

Terbufos Insecticide 82675 13071-79-9 0.012 HAL-US 0.4 –

Terbufos oxygen analog sulfone Degradate 61674 56070-15-6 0.045 na na –1

Terbuthylazine Herbicide 04022 5915-41-3 0.0083 na na –

Thiobencarb Herbicide 82681 28249-77-6 0.01 MCL-CA 70 –

Tribufos Herbicide 61610 78-48-8 0.035 na na –1

Trifluralin Herbicide 82661 1582-09-8 0.009 HAL-US 10 –1

1

 The median matrix-spike recovery was less than 70 percent. Low recoveries may indicate that the compound would not have been detected in some samples 

if it was present at very low concentrations.

2

 Detected at less than the LT-MDL in at least one sample.

Table 3B. Pesticides and pesticide degradates, primary uses or sources, comparative thresholds, and reporting information for the 

U.S. Geological Survey National Water Quality Laboratory schedule 2033.—Continued

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. CAS number: This report contains 

CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through CAS Client 

ServicesSM . Threshold type: 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.Abbreviations: CAS, Chemical Abstract Service; LRL, laboratory reporting level; 

HAL-US, U.S. Environmental Protection Agency Lifetime Health Advisory; MCL-CA, California Department of Public Health maximum contaminant level; 

MCL-US, U.S. Environmental Protection Agency maximum contaminant level; RSD5-US, U.S. Environmental Protection Agency risk specific dose at a risk 

factor of 10-5; D, detected; na, not available; μg/L, micrograms per liter; –, not detected; LT-MDL, long-term method detection limit]
30 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Constituent Primary use 

or source

USGS 

parameter 

code

CAS 

number

 LRL 

(μg/L)

Threshold 

type

Threshold 

value 

(μg/L)

Detection

Acifluorfen Herbicide 49315 50594-66-6 0.06 na na –1

Aldicarb Insecticide 49312 116-06-3 0.04 MCL-US 3 –1

Aldicarb sulfone Degradate 49313 1646-88-4 0.08 MCL-US 3 –1

Aldicarb sulfoxide Degradate 49314 1646-87-3 0.04 MCL-US 4 –

Atrazine Herbicide 39632 1912-24-9 0.04 MCL-CA 1 D

Bendiocarb Insecticide 50299 22781-23-3 0.04 na na –

Benomyl Fungicide 50300 17804-35-2 0.02 na na –

Bensulfuron-methyl Herbicide 61693 83055-99-6 0.06 na na –

Bentazon Herbicide 38711 25057-89-0 0.02 MCL-CA 18 –1

Bromacil Herbicide 04029 314-40-9 0.04 HAL-US 70 D

Bromoxynil Herbicide 49311 1689-84-5 0.12 na na –1,2

Caffeine Stimulant 50305 58-08-2 0.04 na na –

Carbaryl Herbicide 49310 63-25-2 0.02 RSD5-US 400 –

Carbofuran Herbicide 49309 1563-66-2 0.06 MCL-CA 18 –

Chloramben methyl ester Herbicide 61188 7286-84-2 0.1 na na –

Chlorimuron-ethyl Herbicide 50306 90982-32-4 0.08 na na –

2-Chloro-4-isopropylamino-6-amino-striazine (Deethylatrazine, CIAT)

Degradate 04040 6190-65-4 0.02 na na D1

2-Choro-6-ethylamino-4-amino-striazine (Deisopropylatrazine, CEAT)

Degradate 04038 1007-28-9 0.08 na na D1

3-(4-Chlorophenyl)-1-methyl urea Degradate 61692 5352-88-5 0.06 na na –1,2

Clopyralid Herbicide 49305 1702-17-6 0.06 na na –

Cycloate Herbicide 04031 1134-23-2 0.06 na na –

2,4-D (2,4-Dichlorophenoxyacetic acid) Herbicide 39732 94-75-7 0.04 MCL-US 70 –

2,4-D methyl ester 

(2,4-Dichlorophenoxyacetic acid 

methyl ester)

Herbicide 50470 1928-38-7 0.2 na na –

2,4-DB (4-(2,4-Dichlorophenoxy) butyric 

acid)

Herbicide 38746 94-82-6 0.02 na na –1

DCPA (Dacthal) monoacid Degradate 49304 887-54-7 0.02 na na –

Dicamba Herbicide 38442 1918-00-9 0.08 HAL-US 4000 –1

Dichlorprop Herbicide 49302 120-36-5 0.04 na na –

Dinoseb Herbicide 49301 88-85-7 0.04 MCL-CA 7 –1,2

Diphenamid Herbicide 04033 957-51-7 0.04 HAL-US 200 –2

Diuron Herbicide 49300 330-54-1 0.04 RSD5-US 20 D

Fenuron Herbicide 49297 101-42-8 0.04 na na –

Flumetsulam Herbicide 61694 98967-40-9 0.06 na na –

Fluometuron Herbicide 38811 2164-17-2 0.04 HAL-US 90 –

2-Hydroxy-4-isopropylamino-6-

ethylamino-s-triazine (Hydroxyatrazine)

Degradate 50355 2163-68-0 0.08 na na –2

3-Hydroxy carbofuran Degradate 49308 16655-82-6 0.02 na na –

Imazaquin Herbicide 50356 81335-37-7 0.04 na na –

Imazethapyr Herbicide 50407 81335-77-5 0.04 na na –2

Table 3C. Polar pesticides and pesticide degradates, primary uses or sources, comparative thresholds, and reporting information for 

the U.S. Geological Survey National Water Quality Laboratory schedule 2060.

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. CAS number: This report contains 

CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through CAS Client 

ServicesSM . Threshold type: 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. Abbreviations: LRL, laboratory reporting level; CAS, Chemical Abstract Service; 

HAL-US, U.S. Environmental Protection Agency Lifetime Health Advisory; MCL-CA, California Department of Public Health maximum contaminant level; 

MCL-US, U.S. Environmental Protection Agency maximum contaminant level; RSD5-US, U.S. Environmental Protection Agency risk specific dose at a risk 

factor of 10-5; D, detected; na, not available; μg/L, micrograms per liter; –, not detected; LT-MDL, long-term method detection limit]
Table 3C 31

Constituent Primary use 

or source

USGS 

parameter 

code

CAS 

number

 LRL 

(μg/L)

Threshold 

type

Threshold 

value 

(μg/L)

Detection

Imidacloprid Insecticide 61695 138261-41-3 0.06 na na –2

Linuron Herbicide 38478 330-55-2 0.04 na na –

MCPA (2-Methyl-4-chlorophenoxyacetic 

acid)

Herbicide 38482 94-74-6 0.06 HAL-US 30 –1

MCPB (4-(2-Methyl-4-chlorophenoxy) 

butyric acid)

Herbicide 38487 94-81-5 0.2 na na –1

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 0.06 HAL-US 200 –

Metsulfuron methyl Herbicide 61697 74223-64-6 0.14 na na –

Neburon Herbicide 49294 555-37-3 0.02 na na –

Nicosulfuron Herbicide 50364 111991-09-4 0.1 na na –

Norflurazon Herbicide 49293 27314-13-2 0.04 na na D

Oryzalin Herbicide 49292 19044-88-3 0.04 na na –

Oxamyl Insecticide 38866 23135-22-0 0.04 MCL-CA 50 –

Picloram Herbicide 49291 1918-02-1 0.12 MCL-US 500 –1

Propham Herbicide 49236 122-42-9 0.06 HAL-US 100 –

Propiconazole Fungicide 50471 60207-90-1 0.06 na na –

Propoxur (Baygon) Insecticide 38538 114-26-1 0.04 HAL-US 3 –

Siduron Herbicide 38548 1982-49-6 0.04 na na –2

Sulfometuron methyl Herbicide 50337 74222-97-2 0.06 na na –

Tebuthiuron Herbicide 82670 34014-18-1 0.016 HAL-US 500 –2

Terbacil Herbicide 04032 5902-51-2 0.04 HAL-US 90 –

Triclopyr Herbicide 49235 55335-06-3 0.04 na na –

1

 The median matrix-spike recovery was less than 70 percent. Low recoveries may indicate that the compound would not have been detected in some samples 

if it was present at very low concentrations. 

2

 Detected at less than the LT-MDL in at least one sample.

Table 3C. Polar pesticides and pesticide degradates, primary uses or sources, comparative thresholds, and reporting information for 

the U.S. Geological Survey National Water Quality Laboratory schedule 2060.—Continued

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. CAS number: This report contains 

CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through CAS Client 

ServicesSM . Threshold type: 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. Abbreviations: LRL, laboratory reporting level; CAS, Chemical Abstract Service; 

HAL-US, U.S. Environmental Protection Agency Lifetime Health Advisory; MCL-CA, California Department of Public Health maximum contaminant level; 

MCL-US, U.S. Environmental Protection Agency maximum contaminant level; RSD5-US, U.S. Environmental Protection Agency risk specific dose at a risk 

factor of 10-5; D, detected; na, not available; μg/L, micrograms per liter; –, not detected; LT-MDL, long-term method detection limit]
32 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Constituent Primary use 

or source

USGS 

parameter 

code

CAS 

number

 LRL 

(μg/L)

Threshold 

type

Threshold 

value 

(μg/L)

Detection

Acetaminophen Analgesic 62000 103-90-2 0.025 na na D1

Caffeine Stimulant 50305 58-08-2 0.015 na na D

Carbamazepine Anticonvulsant; analgesic; 

mood stabilizer

62793 298-46-4 0.030 na na D

Codeine Opiod narcotic 62003 76-57-3 0.020 na na –

Cotinine Nicotine metabolite 62005 486-56-6 0.030 na na –

Dehydronifedipine Antianginal metabolite 62004 67035-22-7 0.020 na na –

Diltiazem Antianginal; antihypertensive 62008 42399-41-7 0.040 na na –1

1,7-Dimethylxanthine Caffeine metabolite 62030 611-59-6 0.020 na na D

Diphenhydramine Antihistamine 62796 58-73-1 0.050 na na –1

Salbutamol (albuterol) Anti-inflammatory; 

bronchodilator

62020 18559-94-9 0.015 na na –

Sulfamethoxazole Antibacterial, antiprotozoal 62021 723-46-6 0.10 na na –1

Thiabendazole Anthelmintic 62801 148-79-8 0.10 na na –

Trimethoprim Antibacterial 62023 738-70-5 0.040 na na –

Warfarin Anticoagulant 62024 81-81-2 0.020 na na –1

1

 The median matrix-spike recovery was less than 70 percent. Low recoveries may indicate that the compound would not have been detected in some samples 

if it was present at very low concentrations.

Table 3D. Pharmaceutical compounds, primary uses or sources, comparative thresholds, and reporting information for the U.S. 

Geological Survey National Water Quality Laboratory schedule 2080.

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. CAS number: This report contains CAS 

Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through CAS Client 

ServicesSM. Abbreviations: CAS, Chemical Abstract Service; IRL, interim reporting level; D, detected; na, not available; μg/L, micrograms per liter; –, not 

detected]
Table 3E 33

Constituent Primary use 

or source

USGS 

parameter 

code

CAS 

number

 LRL 

(μg/L)

Threshold 

type

Threshold 

value 

(μg/L)

Acetophenone Fragrance, flavor additive 62811 98-86-2 0.2 na na

Acetyl hexamethyl 

tetrahydronaphthalene (AHTN) 

Musk fragrance 62812 21145-77-7 0.2 na na

Anthracene Wood preservative, combustion 

product 

34220 120-12-7 0.2 na na

Anthraquinone Dye/textiles, seed treatment 62813 84-65-1 0.2 na na

Atrazine Herbicide 39630 1912-24-9 0.2 MCL-CA 1

Benzo[a]pyrene Combustion product 34247 50-32-8 0.2 MCL-US 0.2

Benzophenone Fixative for perfumes and soaps 62814 119-61-9 0.2 na na

Bisphenol A Polycarbonate resins, flame 

retardant

62816 80-05-7 0.4 na na

Bis(2-ethylhexyl)phthalate Plasticizer, softener 39100 117-81-7 2 MCL-US 6

Bromacil Herbicide 30234 314-40-9 0.2 HAL-US 70

Bromoform (tribromomethane) Disinfection by-product 32104 75-25-2 0.2 MCL-US 80

3-tert-Butyl-4-hydroxy anisole 

(BHA) 

Antioxidant, general 

preservative 

61702 25013-16-5 0.2 na na

Caffeine Beverages 81436 58-08-2 0.2 na na

Camphor Flavor, odorant, ointments 62817 76-22-2 0.2 na na

Carbaryl Insecticide 39750 63-25-2 0.2 RSD5-US 400

Carbazole Insecticide 77571 86-74-8 0.2 na na

Chlorpyrifos Insecticide 38932 2921-88-2 0.2 HAL-US 20

Cholesterol Fecal indicator, plant sterol 62818 57-88-5 0.8 na na

3-beta-Coprostanol Carnivore fecal indicator 62806 360-68-9 0.8 na na

Cotinine Primary nicotine metabolite 61945 486-56-6 0.8 na na

para-Cresol Wood preservative 77146 106-44-5 0.2 na na

4-Cumylphenol Nonionic detergent metabolite 62808 599-64-4 0.2 na na

Diazinon Insecticide 39570 333-41-5 0.2 HAL-US 1

N,N-diethyl-m-toluamide (DEET) Insecticide 61947 134-62-3 0.2 na na

1,4-Dichlorobenzene Moth repellant, fumigant, 

deodorant 

34571 106-46-7 0.2 MCL-CA 5

3,4- Dichlorophenyl isocyanate Intermediate for the synthesis of 

organic compounds

63145 102-36-3 2 na na

Dichlorvos Insecticide 30218 62-73-7 0.2 na na

Diethyl phthalate Wood stains and varnishes, 

plasticizer, softener

34336 84-66-2 0.2 na na

2,6-Dimethylnaphthalene Diesel/kerosene 62805 581-42-0 0.2 na na

4-Nonylphenol diethoxylates Nonionic detergent metabolite 61703 na 3.2 na na

4-Octylphenol diethoxylates Nonionic detergent metabolite 61705 na 0.32 na na

Nonylphenol, monoethoxylates 

(total)

Nonionic detergent metabolite 61704 na 2 na na

4-Octylphenol monoethoxylates Nonionic detergent metabolite 61706 na 1 na na

Fluoranthene Component of coal tar and 

asphalt 

34376 206-44-0 0.2 na na

Hexahydrohexamethylcyclopentabenzopyran (HHCB) Musk fragrance 62823 1222-05-5 0.2 na na

Table 3E. Wastewater-indicator compounds, primary uses or sources, comparative thresholds, and reporting information for the U.S. 

Geological Survey National Water Quality Laboratory schedule 4433. 

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. NOTE: Results for this group of 

compounds are not presented in this report because results from quality-control samples suggest that these data are unreliable. CAS number: This report 

contains CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through 

CAS Client ServicesSM. Threshold type: 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. Abbreviations: CAS, Chemical Abstract Service; LRL, laboratory reporting 

level; HAL-US, U.S. Environmental Protection Agency Lifetime Health Advisory; MCL-CA, California Department of Public Health maximum contaminant 

level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; NL-CA, California Department of Public Health notification level; 

RSD5-US, U.S. Environmental Protection Agency risk specific dose at a risk factor of 10-5; D, detected; na, not available; μg/L, micrograms per liter]
34 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Constituent Primary use 

or source

USGS 

parameter 

code

CAS 

number

 LRL 

(μg/L)

Threshold 

type

Threshold 

value 

(μg/L)

Indole Pesticide ingredient 62824 120-72-9 0.2 na na

Isoborneol Fragrance in perfumery 62825 124-76-5 0.2 na na

Isophorone Solvent 34408 78-59-1 0.2 HAL-US 100

Isopropylbenzene Fuels, paint thinner 77223 98-82-8 0.2 NL-CA 770

Isoquinoline Flavors and fragrances 62826 119-65-3 0.2 na na

d-Limonene Fungicide, solvent 62819 5989-27-5 0.2 na na

Menthol Cigarettes, cough drops, 

liniment

62827 89-78-1 0.2 na na

Metalaxyl Herbicide, fungicide 04254 57837-19-1 0.2 na na

3-Methyl-1(H)-indole (Skatole) Fragrance, stench in feces 62807 83-34-1 0.2 na na

5-Methyl-1H-benzotriazole Antioxidant in antifreeze and 

deicers 

61944 136-85-6 1.6 na na

1-Methylnaphthalene Gasoline, diesel fuel, or crude 

oil 

81696 90-12-0 0.2 na na

2-Methylnaphthalene Gasoline, diesel fuel, or crude 

oil 

30194 91-57-6 0.2 na na

Methyl salicylate Liniment, UV-absorbing lotion 62828 119-36-8 0.2 na na

Metolachlor Herbicide 82612 51218-45-2 0.2 HAL-US 700

Naphthalene Fumigant, moth repellent, 

gasoline 

34696 91-20-3 0.2 NL-CA 17

para-Nonylphenol (total) Nonionic detergent metabolite 62829 84852-15-3 1.6 na na

4-n-Octylphenol Nonionic detergent metabolite 62809 1806-26-4 0.2 na na

4-tert-Octylphenol Nonionic detergent metabolite 62810 140-66-9 0.2 na na

Pentachlorophenol Fumigant, moth repellent, 

gasoline 

39032 87-86-5 0.8 MCL-US 1

Phenanthrene Manufactured explosives 34461 85-01-8 0.2 na na

Phenol Disinfectant, organic synthesis 34694 108-95-2 0.2 HAL-US 2,000

Prometon Herbicide 39056 1610-18-0 0.2 HAL-US 100

Pyrene Component of coal tar and 

asphalt 

34469 129-00-0 0.2 na na

beta-Sitosterol Plant sterol 62815 83-46-5 0.8 na na

beta-Stigmastanol Plant sterol 61948 19466-47-8 0.8 na na

2,2',4,4'- Tetrabromodiphenyl ether Brominated flame retardant 63147 5436-43-1 0.2 na na

Tetrachloroethylene (PCE) Solvent, degreaser 34475 127-18-4 0.4 MCL-US 5

Tributyl phosphate Antifoaming agent, flame 

retardant 

62832 126-73-8 0.2 na na

Triclosan Disinfectant, antimicrobial 61708 3380-34-5 0.2 na na

Triethyl citrate (ethyl citrate) Cosmetics, pharmaceuticals 62833 77-93-0 0.2 na na

Triphenyl phosphate Plasticizer 62834 115-86-6 0.2 na na

Tris(2-butoxyethyl)phosphate Flame retardant 62830 78-51-3 0.2 na na

Tris(2-chloroethyl)phosphate Plasticizer, flame retardant 62831 115-96-8 0.2 na na

Tris(dichlorisopropyl)phosphate Flame retardant 61707 13674-87-8 0.2 na na

Table 3E. Wastewater-indicator compounds, primary uses or sources, comparative thresholds, and reporting information for the U.S. 

Geological Survey National Water Quality Laboratory schedule 4433.—Continued

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. NOTE: Results for this group of 

compounds are not presented in this report because results from quality-control samples suggest that these data are unreliable. CAS number: This report 

contains CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through 

CAS Client ServicesSM. Threshold type: 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. Abbreviations: CAS, Chemical Abstract Service; LRL, laboratory reporting 

level; HAL-US, U.S. Environmental Protection Agency Lifetime Health Advisory; MCL-CA, California Department of Public Health maximum contaminant 

level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; NL-CA, California Department of Public Health notification level; 

RSD5-US, U.S. Environmental Protection Agency risk specific dose at a risk factor of 10-5; D, detected; na, not available; μg/L, micrograms per liter]
Table 3F 35

Constituent Primary use 

or source

USGS 

parameter 

code

CAS 

number

 MRL 

(μg/L)

Threshold 

type

Threshold 

value 

(μg/L)

Detection

Perchlorate Rocket fuel, fireworks, flares 61209 14797-73-0 0.5 MCL-CA 6 D

1,4-Dioxane Industrial solvent, solvent 

stabilizer

81582 123-91-1 2.0 NL-CA 3 –1

1,2,3-Trichloropropane (TCP) Industrial solvent, organic 

synthesis

77443 96-18-4 0.005 HAL-US 40 D

N-Nitrosodimethylamine 

(NDMA)

Rocket fuel, plasticizer, 

disinfection by-product

64176 62-75-9 0.002 NL-CA 0.010 D2

1The median matrix-spike recovery was less than 70 percent. Low recoveries may indicate that the compound would not have been detected in some samples 

if it was present at very low concentrations.

2NDMA was detected at a concentration below the concentration detected in a blank sample. Detections in ground-water samples could be attributed to unintended sample contamination.

Table 3F. Constituents of special interest, primary uses or sources, comparative thresholds, and reporting information for the 

Montgomery Watson-Harza Laboratory.

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. CAS number: This report contains 

CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through CAS Client 

ServicesSM. Threshold type: 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. Abbreviations: CAS, Chemical Abstract Service; MRL, minimum reporting level; 

MCL-CA, California Department of Public Health maximum contaminant level; NL-CA, California notification level; D, detected; μg/L, micrograms per liter; 

–, not detected] 

Constituent

USGS 

parameter 

code

CAS 

number

 LRL 

(mg/L)

Threshold 

type

Threshold 

value 

(mg/L)

Detection

Ammonia 00608 7664-41-7 0.02 HAL-US 130 D

Nitrite (as nitrogen) 00613 14797-65-0 0.002 MCL-US 1 D

Nitrite plus nitrate (as nitrogen) 00631 12797-55-8 plus 

14797-65-0

0.060 MCL-US 10 D

Total nitrogen (ammonia, nitrite, 

nitrate, organic nitrogen)

62854 17778-88-0 0.06 na na D

Phosphorus, phosphate, 

orthophosphate (as phosphorus)

00671 14265-44-2 0.006 na na D

Dissolved organic carbon (DOC) 00681 na 0.4 na na D

1

Threshold for ammonia is as ammonia; results are listed as nitrogen.

Table 3G. Nutrients and dissolved organic carbon, comparative thresholds, and reporting information for the U.S. Geological Survey 

National Water Quality Laboratory schedule 2755 and lab code 2612.

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. CAS number: This report contains CAS 

Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through CAS Client 

ServicesSM. Threshold value: 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. Abbreviations: CAS, Chemical Abstract Service; HAL-US, U.S. Environmental 

Protection Agency Lifetime Health Advisory Level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; D, detected; na, not 

available; mg/L, milligrams per liter]
36 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Constituent

USGS 

parameter 

code

CAS 

number LRL Threshold 

type

Threshold 

value Detection

Major and minor ions, silica, and total dissolved solids (mg/L)

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 1 250 (500) D

Fluoride 00950 16984-48-8 0.10 MCL-CA 2 D

Iodide 78165 7553-56-2 0.002 na na D

Magnesium 00925 7439-95-4 0.014 na na D

Potassium 00935 7440-09-7 0.04 na na D

Silica (as SiO2

) 00955 7631-86-9 0.018 na na D

Sodium 00930 7440-23-5 0.20 na na D

Sulfate 00945 14808-79-8 0.18 SMCL-CA 1 250 (500) D

Residue on evaporation (total dissolved solids, TDS) 70300 na 10 SMCL-US 1 500 (1,000) D

Trace elements (μg/L)

Aluminum 01106 7429-90-5 1.6 MCL-CA 1,000 D

Antimony 01095 7440-36-0 0.06 MCL-US 6 D

Arsenic 01000 7440-38-2 0.12 MCL-US 10 D

Barium 01005 7440-39-3 0.08 MCL-CA 1,000 D

Beryllium 01010 7440-41-7 0.06 MCL-US 4 –

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

Cadmium 01025 7440-43-9 0.04 MCL-US 5 D

Chromium 01030 7440-47-3 0.12 MCL-CA 50 D

Cobalt 01035 7440-48-4 0.04 na na D

Copper 01040 7440-50-8 0.4 AL-US 1,300 D

Iron 01046 7439-89-6 6 SMCL-CA 300 D

Lead 01049 7439-92-1 0.12 AL-US 15 D

Lithium 01130 7439-93-2 0.6 na na D

Manganese 01056 7439-96-5 0.2 SMCL-CA 50 D

Mercury 71890 7439-97-6 0.01 MCL-US 2 D

Molybdenum 01060 7439-98-7 0.12 HAL-US 40 D

Nickel 01065 7440-02-0 0.06 MCL-CA 100 D

Selenium 01145 7782-49-2 0.08 MCL-US 50 D

Silver 01075 7440-22-4 0.1 SMCL-CA 100 D

Strontium 01080 7440-24-6 0.4 HAL-US 4,000 D

Thallium 01057 7440-28-0 0.04 MCL-US 2 D

Tungsten 01155 7440-33-7 0.06 na na D

Uranium 22703 7440-61-1 0.04 MCL-US 30 D

Vanadium 01085 7440-62-2 0.1 NL-CA 50 D

Zinc 01090 7440-66-6 0.6 SMCL-US 5,000 D

1The recommended SMCL-CA thresholds for chloride, sulfate, and TDS are listed with the upper SMCL-CA thresholds in parentheses.

Table 3H. Major and minor ions, silica, total dissolved solids, and trace elements, comparative thresholds, and reporting information 

for the USGS National Water Quality Laboratory schedule 1948.

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. CAS number: This report contains 

CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through CAS Client 

ServicesSM. Threshold type: 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 Abbreviations: CAS, Chemical Abstract Service; AL-US, U.S. Environmental Protection 

Agency action level; HAL-US, U.S. Environmental Protection Agency Lifetime Health Advisory; MCL-CA, California Department of Public Health maximum 

contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; NL-CA, California Department of Public Health notification 

level; SMCL-CA, California Department of Public Health secondary maximum contaminant level; SMCL-US, U.S. Environmental Protection Agency secondary 

maximum contaminant level; D, detected; na, not available; mg/L, milligrams per liter; μg/L, micrograms per liter; –, not detected]
Table 3I 37

Constituent 

(valence state)

USGS 

parameter 

code

CAS 

number

MDL 

(μg/L)

Threshold 

type

Threshold 

value 

(μg/L)

Detection

Arsenic(III) 99034 22569-72-8 1 na na –

Arsenic (total) 01000 7440-38-2 0.5 MCL-US 10 D

Chromium(VI) 01032 18540-29-9 1 na na D

Chromium (total) 01030 7440-47-3 1 MCL-CA 50 D

Iron(II) 01047 7439-89-6 2 na na D

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

Table 3I. Arsenic, chromium, and iron species, comparative thresholds, and reporting information for the U.S. Geological Survey Trace 

Metal Laboratory, Boulder, Colorado.

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. CAS number: This report contains CAS 

Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through CAS Client 

ServicesSM. Threshold type: 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. Abbreviations: CAS, Chemical Abstract Service; MDL, method detection limit; 

MCL-CA, California Department of Public Health maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; 

SMCL-CA, California Department of Public Health secondary maximum contaminant level; na, not available; μg/L, micrograms per liter; D, detected; –, not 

detected]
38 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Constituent 

USGS 

parameter 

code

CAS 

number

Reporting 

level 

type

Reporting 

level or 

uncertainty type

Threshold 

type

Threshold 

value

Reporting 

units Detection

1Radon-222 82303 14859-67-7 SSMDC 2 σ CSU and CV Proposed 

MCL-US2

300, 4,000 pCi/L D

Tritium3,4 07000 10028-17-8 MRL 1 MCL-CA 20,000 pCi/L D

δ2H of water5 82082 na MU 2 na na per mil D

δ18O of water5 82085 na MU 0.20 na na per mil D

δ15N of nitrate5 82690 na MU na na na per mil D

δ18O of nitrate5 63041 na MU na na na per mil D

δ15N of nitrogen gas5 82698 na MU na na na per mil D

Gross-alpha radioactivity, 

72-hour and 30-day counts6

62636, 62639 12587-46-1 SSMDC 2 σ CSU and CV MCL-US 15 pCi/L D

Gross-beta radioactivity, 

72-hour and 30-day counts6

62642, 62645 12587-47-2 SSMDC 2 σ CSU and CV MCL-US 4 pCi/L D

6Radium-226 09511 13982-63-3 SSMDC 2 σ CSU and CV MCL-US9 5 pCi/L D

6Radium-228 81366 15262-20-1 SSMDC 2 σ CSU and CV MCL-US9 5 pCi/L D

δ13C of dissolved carbonates7 82081 na 1 σ 0.05 na na per mil D

8Carbon-14 49933 14762-75-5 1 σ 0.0015 na na percent 

modern

D

1

 USGS National Water Quality Laboratory

2

 Two MCL-US thresholds have been proposed, 300 pCi/L and 4,000 pCi/L.

3

 USGS Stable Isotope and Tritium Laboratory, Menlo Park, California

4

 Lawrence Livermore National Laboratory—tritium data from this laboratory not available for this report

5

 USGS Stable Isotope Laboratory, Reston, Virginia

6

 Eberline Analytical Services (contract laboratory)

7

 University of Waterloo (contract laboratory)

8 University of Arizona, Accelerator Mass Spectrometry Laboratory (contract laboratory)

9

 The MCL-US threshold for radium is the sum of radium-226 and radium-228

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

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. CAS number: This report contains 

CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through CAS Client 

ServicesSM.

 Threshold type: 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. Abbreviations: CAS, Chemical Abstract Service; Laboratory entity codes are listed in 

the footnotes. 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. MCL-CA, California Department of Public Health maximum contaminant level; MCL-US, U.S. Environmental 

Protection Agency maximum contaminant level; MRL, minimum reporting level; MU, method uncertainty; na, not available; pCi/L, picocuries per liter; per 

mil, per thousand; CSU, combined standard uncertainty; CV, critical value; SSMDC, sample specific minimum detectable concentration; σ, sigma (standard 

deviation); D, detected]
Table 3K 39

Constituent 

USGS 

parameter 

code

CAS 

number

MU

(percent)

Reporting 

units

Threshold 

type

Threshold 

value Detection

Standard dissolved gases1

Methane 76994 74-82-8 na mg/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

Noble gases2

Argon na 7440-37-1 2 cm3STP/g na na D

Helium-3 / Helium-4 ratio na na / 7440-59-7 0.75 atom ratio na na D

Helium-4 na 7440-59-7 2 cm3STP/g na na D

Krypton na 7439-90-9 2 cm3STP/g na na D

Neon na 7440-01-09 2 cm3STP/g na na D

Xenon na 7440-63-3 2 cm3STP/g na na D

1

Analyzed by the U.S. Geological Survey Reston Chlorofluorocarbon Laboratory.

2

Analyzed by the Lawrence Livermore National Laboratory.

Table 3K. Dissolved and noble gases, comparative thresholds, and reporting information for dissolved gases analyzed by the U.S. 

Geological Survey Chlorofluorocarbon Laboratory (CFC) and the Lawrence Livermore National Laboratory (LLNL).

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. CAS number: This report contains 

CAS Registry Numbers®, which is a Registered Trademark of the American Chemical Society. CAS recommends verifying the CASRNs through CAS Client 

ServicesSM. Abbreviations: CAS, Chemical Abstract Service. The laboratory entity code for the Lawrence Livermore National Laboratory in the USGS 

National Water Information System (NWIS) is CA-LLNL. MU, method uncertainty; na, not available; mg/L, milligrams per liter; cm3 STP/g, cubic centimeters 

of gas at standard temperature and pressure per gram of water; pCi/L, picocuries per liter; D, detected]

Constituent 

USGS 

parameter 

code

Primary 

source

MDL Threshold 

type

Threshold 

value Detection

Escherichia coli 1 90901 Sewage and animal waste indicator / 

intestinal tracts of humans and 

animals

1 colony / 

100 mL

TT-US Zero –

Total coliform - including 

fecal coliform and E. coli1

90900 Water-quality indicator / soil, water 

and intestinal tracts of animals

1 colony / 

100 mL

MCL-US 5 percent of samples 

positive per month

D

F-specific coliphage2 99335 Viral indicator / intestinal tracts of 

warm-blooded animals

na TT-US 99.99 percent killed/

inactivated

–

Somatic coliphage2 99332 Viral indicator / fecal contaminated 

waters

na TT-US 99.99 percent killed/

inactivated

–

1

 Analyzed in the field.

2

 Analyzed by the U.S. Geological Survey Ohio Microbiology Laboratory (laboratory entity code USGSOHML).

Table 3L. Microbial constituents, comparison thresholds, and reporting information for the U.S. Geological Survey Ohio Microbiology 

Laboratory parameter codes 90901, 90900, 99335 and 99332.

[The five-digit U.S. Geological Survey parameter code is used to uniquely identify a specific constituent or property. Threshold type: 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. Abbreviations: MDL, method detection limit; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; TT-US, U.S. 

Environmental Protection Agency treatment technique - a required process intended to reduce the level of contamination in drinking water; na, not available; 

mL, milliliters; D, detected; –, not detected]
40 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program GAMA well identification number Turbidity, field (NTU) (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 25°C) (90095) Specific conductance, field (μS/cm at 25°C) (00095) Alkalinity, lab (mg/L as CaCO3) (29801) Alkalinity, field (mg/L as CaCO3) (29802) Bicarbonate, field (mg/L) (63786) Carbonate, field (mg/L) (63788) Threshold type SMCL-CA na na SMCL-US SMCL-US SMCL-CA1 SMCL-CA1 na na na na Threshold level 5 na na 6.5 - 8.5 6.5 - 8.5 900 (1,600) 900 (1,600) na na na na Grid wells USAWB-01 nc 1.2 24.5 nc 8.0 nc 525 nc nc nc nc USAWB-02 0.2 8.0 15.0 7.7 7.3 313 314 137 132 160 – USAWB-03 nc 4.7 16.5 nc 7.4 nc 660 nc nc nc nc USAWB-04 0.3 10.0 18.5 8.1 7.9 312 299 120 124 150 – USAWB-05 nc 9.8 16.5 nc 7.3 nc 437 nc nc nc nc USAWB-06 nc 8.1 20.0 nc 7.4 nc 485 nc nc nc nc USAWB-07 0.3 5.5 19.5 7.8 7.7 517 513 141 147 178 – USAWB-08 0.2 8.8 18.5 7.5 7.4 593 577 190 224 272 – USAWB-09 nc 20.2 17.5 nc 7.2 nc 723 nc nc nc nc USAWB-10 0.3 9.6 19.0 7.6 7.6 622 618 204 193 234 – USAWB-11 0.4 8.1 21.5 7.4 7.3 674 663 154 147 178 – USAWB-12 nc nc 19.0 nc 7.3 nc 353 nc nc nc nc USAWB-13 nc nc 22.5 nc 7.6 nc 647 nc nc nc nc USAWB-14 0.4 11.0 19.5 7.8 7.4 367 365 168 157 189 – USAWB-15 nc nc 17.5 nc 7.6 nc 382 nc nc nc nc USAWB-16 nc 4.0 22.0 7.7 7.8 342 339 112 nc nc nc USAWB-17 nc 7.9 18.0 nc 7.2 nc 355 nc nc nc nc USAWB-18 nc 11.1 20.0 7.6 7.7 402 405 148 nc nc nc USAWB-19 nc 7.7 17.5 nc nc nc 480 nc nc nc nc USAWC-01 nc 7.8 22.5 7.8 8.0 397 394 138 nc nc nc USAWC-02 nc 7.7 22.0 7.8 8.0 368 360 162 nc nc nc USAWC-03 nc 9.1 19.5 nc 7.9 nc 346 nc nc nc nc USAWC-04 0.1 9.1 19.5 7.6 7.5 776 760 205 198 240 – USAWC-05 nc 10.6 19.5 nc 7.6 nc 543 nc nc nc nc USAWC-06 nc 7.8 17.5 nc 7.8 nc 454 nc nc nc nc USAWC-07 nc 0.7 21.0 nc 7.5 nc *944 nc nc nc nc USAWC-08 0.1 8.1 21.5 7.7 7.7 580 569 147 144 175 – USAWC-09 nc – 24.5 nc *8.6 nc *925 nc nc nc nc USAWC-10 nc 10.6 26.0 nc 8.2 nc 420 nc nc nc nc Table 4.

Water-quality indicators in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, 

November 2006 to March 2007.[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five digit number below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Abbreviations: SMCL-CA, California Department of Public Health secondary maximum contaminant level; SMCL-US, U.S. Environmental Protection Agency secondary maximum contaminant level; C, Celsius; mg/L, milligrams per liter; nc, sample not collected; na, not available; NTU, nephelometric turbidity unit; μS/cm, microsiemens per centimeter; CaCO3, calcium carbonate; –, not detected]
Table 4

41

GAMA well

identification 

number

Turbidity, 

field 

(NTU) 

(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 

25°C)

 (90095)

Specific 

conductance, 

field 

(μS/cm at 

25°C) 

(00095)

Alkalinity, 

lab 

(mg/L as 

CaCO3) 

(29801)

Alkalinity, 

field 

(mg/L as 

CaCO3) 

(29802)

Bicarbonate, 

field 

(mg/L) 

(63786)

Carbonate, 

field 

(mg/L) 

(63788)

Threshold type SMCL-CA na na SMCL-US SMCL-US SMCL-CA1 SMCL-CA1 na na na na

Threshold level 5 na na 6.5 - 8.5 6.5 - 8.5 900 (1,600) 900 (1,600) na na na na

Grid wells–Continued

USAWC-11 0.2 6.2 22.5 7.6 7.4 876 872 235 230 279 –

USAWC-12 nc 4.7 20.5 7.4 7.5 *1,130 *1,120 289 nc nc nc

USAWC-13 nc 6.5 21.5 nc 7.4 nc 470 nc nc nc nc

USAWC-14 0.2 7.7 20.5 7.8 7.5 404 402 149 144 174 –

USAWC-15 nc 5.8 21.0 nc nc nc 522 nc nc nc nc

USAWC-16 nc 8.2 16.0 nc 7.5 nc 473 nc nc nc nc

USAWC-17 0.2 9.6 20.5 7.9 7.7 382 394 165 157 190 –

USAWC-18 nc 7.9 20.5 nc 7.7 nc 407 nc nc nc nc

USAWC-19 nc 7.0 14.0 nc 7.2 nc 297 nc nc nc nc

USAWC-20 nc 7.8 21.5 7.6 7.8 381 376 166 nc nc nc

USAWC-21 0.2 10.1 21.0 7.6 7.5 427 433 146 141 172 –

USAWC-22 nc 7.6 22.0 nc 7.6 nc 387 nc nc nc nc

USAWC-23 0.2 8.8 20.0 7.5 7.7 475 474 150 143 174 –

USAWC-24 nc 2.2 21.0 7.8 7.9 303 301 110 nc nc nc

USAWC-25 nc 5.7 20.0 7.5 7.4 792 785 169 nc nc nc

USAWE-01 0.3 5.6 23.5 8.0 8.0 *910 887 114 108 132 –

USAWE-02 0.8 0.3 26.5 *9.0 * 9.2 867 876 82 107 119 6

USAWE-03 0.3 1.2 21.5 7.5 7.4 771 767 146 171 208 –

USAWE-04 0.5 8.8 19.0 7.1 7.1 823 811 134 129 157 –

USAWR-01 nc 7.4 20.0 nc 7.4 nc 578 nc nc nc nc

USAWR-02 nc 6.9 21.0 nc 7.6 nc 473 nc nc nc nc

USAWR-03 0.2 6.1 20.5 7.5 7.3 *1,040 *1,040 286 273 332 –

USAWR-04 nc 6.6 20.5 nc 7.1 nc *1,340 nc nc nc nc

USAWR-05 nc 2.0 22.0 nc 7.1 nc 729 207 nc nc nc

USAWR-06 nc 5.8 23.5 7.4 nc *1,490 *1,500 336 nc nc nc

USAWR-07 nc 3.6 21.5 7.3 7.2 **1,690 **1,680 364 nc nc nc

Table 4. Water-quality indicators in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.–Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five digit number below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Abbreviations: SMCL-CA, California Department of Public Health secondary maximum contaminant level; SMCL-US, U.S. Environmental Protection Agency secondary maximum contaminant level; C, Celsius; mg/L, milligrams per liter; nc, sample not collected; na, not available; NTU, nephelometric turbidity unit; μS/cm, microsiemens per centimeter; CaCO3, calcium carbonate; –, not detected]
42 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program GAMA well identification number Turbidity, field (NTU) (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 25°C) (90095) Specific conductance, field (μS/cm at 25°C) (00095) Alkalinity, lab (mg/L as CaCO3) (29801) Alkalinity, field (mg/L as CaCO3) (29802) Bicarbonate, field (mg/L) (63786) Carbonate, field (mg/L) (63788) Threshold type SMCL-CA na na SMCL-US SMCL-US SMCL-CA1 SMCL-CA1 na na na na Threshold level 5 na na 6.5 - 8.5 6.5 - 8.5 900 (1,600) 900 (1,600) na na na na Grid wells–Continued USAWR-08 0.2 0.2 20.5 7.0 7.1 *930 *922 261 249 302 – USAWR-09 nc 6.6 22.0 7.5 7.2 *1,100 *1,110 273 nc nc nc USAWR-10 nc 2.1 23.5 7.5 7.2 *1,250 *1,260 225 nc nc nc USAWR-11 0.3 10.8 19.0 7.7 7.8 406 410 155 125 152 – USAWR-12 0.2 7.9 21.5 7.2 7.3 *1,160 *1,150 244 236 287 – USAWS-01 nc 7.9 21.0 nc 6.9 nc 794 nc nc nc nc USAWS-02 0.2 6.4 22.5 7.6 7.7 **2,070 **2,030 127 121 147 – USAWS-03 nc 6.1 22.0 nc 7.6 nc 767 nc nc nc nc USAWS-04 nc 3.8 22.5 nc 7.0 nc *1,590 nc nc nc nc USAWS-05 nc 9.3 20.5 7.3 6.9 **1,730 **1,660 178 nc nc nc USAWS-06 0.3 0.2 20.0 7.5 7.4 414 403 186 195 237 – USAWS-07 nc 6.3 21.0 nc 6.6 nc **5,220 nc nc nc nc USAWS-08 0.2 9.6 23.5 6.2 6.8 828 831 75 69.1 84 – USAWS-09 nc 7.5 22.0 nc 7.5 nc 823 nc nc nc nc USAWS-10 nc 7.5 21.0 nc 7.7 nc **4,830 nc nc nc nc USAWS-11 nc 6.6 23.0 nc 7.2 nc **2,410 nc nc nc nc USAWS-12 0.2 10.5 22.0 7.4 7.1 *1,230 *1,220 115 106 129 – USAWS-13 nc 7.0 22.5 nc 7.0 nc **3,060 nc nc nc nc USAWS-14 0.2 – 21.5 8.1 8.1 396 394 138 132 159 1 USAWS-15 0.2 0.8 23.5 7.0 7.5 *1,050 *1,060 94 123 150 – USAWS-16 nc 0.6 23.5 7.8 8.2 *947 *944 95 nc nc nc USAWS-17 nc 3.2 22.5 nc 7.9 nc *1,580 nc nc nc nc USAWS-18 0.3 2.5 26.5 7.5 7.5 *1,210 *1,220 105 130 158 – USAWS-19 nc – 23.0 nc * 9.3 nc *907 nc nc nc nc USAWS-20 0.2 4.7 25.5 7.6 7.5 899 *906 126 124 150 – USAWS-21 nc – 24.0 7.8 * 8.7 504 501 191 nc nc nc USAWY-01 nc 8.5 18.5 nc 7.6 nc 395 nc nc nc nc Table 4.

Water-quality indicators in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, 

November 2006 to March 2007.–Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five digit number below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Abbreviations: SMCL-CA, California Department of Public Health secondary maximum contaminant level; SMCL-US, U.S. Environmental Protection Agency secondary maximum contaminant level; C, Celsius; mg/L, milligrams per liter; nc, sample not collected; na, not available; NTU, nephelometric turbidity unit; μS/cm, microsiemens per centimeter; CaCO3, calcium carbonate; –, not detected]
Table 4

43

GAMA well

identification 

number

Turbidity, 

field 

(NTU) 

(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 

25°C)

 (90095)

Specific 

conductance, 

field 

(μS/cm at 

25°C) 

(00095)

Alkalinity, 

lab 

(mg/L as 

CaCO3) 

(29801)

Alkalinity, 

field 

(mg/L as 

CaCO3) 

(29802)

Bicarbonate, 

field 

(mg/L) 

(63786)

Carbonate, 

field 

(mg/L) 

(63788)

Threshold type SMCL-CA na na SMCL-US SMCL-US SMCL-CA1 SMCL-CA1 na na na na

Threshold level 5 na na 6.5 - 8.5 6.5 - 8.5 900 (1,600) 900 (1,600) na na na na

Grid wells–Continued

USAWY-02 nc 6.7 17.5 nc 7.5 nc 413 nc nc nc nc

USAWY-03 nc nc 20.0 nc 7.7 nc 435 nc nc nc nc

USAWY-04 nc nc 21.5 7.8 7.7 430 437 173 nc nc nc

USAWY-05 0.2 6.2 22.0 7.9 7.7 508 511 157 154 187 –

USAWY-06 0.3 8.8 21.0 7.6 7.7 611 600 206 197 239 –

USAWY-07 nc 6.5 16.5 nc 7.0 nc 615 nc nc nc nc

USAWY-08 nc 4.8 16.0 nc nc nc 539 nc nc nc nc

USAWY-09 nc 10.2 19.0 nc 8.0 nc 366 nc nc nc nc

Understanding wells

USAWU-01 nc 0.8 21.0 7.5 7.4 772 760 214 nc nc nc

USAWU-02 nc 4.8 19.5 7.7 7.6 488 479 194 nc nc nc

USAWU-03 nc 5.0 9.5 nc nc nc 261 nc nc nc nc

USAWU-04 nc 7.5 20.0 7.8 7.7 464 456 165 nc nc nc

USAWU-05 nc 8.5 18.5 7.7 7.5 514 511 167 nc nc nc

USAWU-06 nc 9.4 18.0 7.5 7.5 530 521 141 nc nc nc

USAWU-07 nc 7.9 22.5 7.6 nc 449 454 161 nc nc nc

USAWU-08 nc 0.3 26.0 *9.2 * 9.2 249 251 83 nc nc nc

USAWU-09 nc 6.7 19.0 7.3 7.2 789 793 222 nc nc nc

1The SMCL-CA for specific conductance has recommended and upper threshold values. The upper value is shown in parentheses.*Value exceeds threshold.**Value exceeds upper threshold.

Table 4. Water-quality indicators in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.–Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five digit number below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Abbreviations: SMCL-CA, California Department of Public Health secondary maximum contaminant level; SMCL-US, U.S. Environmental Protection Agency secondary maximum contaminant level; C, Celsius; mg/L, milligrams per liter; nc, sample not collected; na, not available; NTU, nephelometric turbidity unit; μS/cm, microsiemens per centimeter; CaCO3, calcium carbonate; –, not detected]
44 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program GAMA well identification number Disinfection by-product (THM) Refrigerant Refrigerant/ organic synthesis Organic synthesis Gasoline Chloroform (trichloro- methane) (μg/L) (32106) Bromodi- chloro methane (μg/L) (32101) Bromoform (Tribromo- methane) (μg/L) (32104) Dibromo- chloro- methane (μg/L) (32105) Dichloro- difluoro- methane (CFC-112) (μg/L) (34668) Trichloro- fluorome- thane (CFC-111) (μg/L) (34488) 1,1,2-Trichloro- 1,2,2-trifluoro- ethane (CFC-113) (μg/L) (77652) Chloro- methane (μg/L) (34418) 1,1- Dichloro- ethene (μg/L) (34501) 1,2,4- Trimethyl- benzene (μg/L) (77222) Methyl tert-butyl ether (μg/L) (78032) Toluene (μg/L) (34010) [LRL] 0.04 0.04 0.08 0.12 0.14 0.08 0.04 0.1 0.02 0.04 0.1 0.02 Threshold type MCL-US MCL-US MCL-US MCL-US NL-CA MCL-CA MCL-CA HAL-US MCL-CA NL-CA MCL-CA MCL-CA Threshold level 801 801 801 801 1,000 150 1,200 30 6 330 13 150 Grid wells USAWB-02 0.50

E0.09 – – – – – – – E0.03 – –

USAWB-03

E0.03 – – – – – – – – – – –

USAWB-05

E0.02 – – – – – – – – – – –

USAWB-06 0.10 – – – – – – – – – 0.2 –

USAWB-07 0.24 0.36 0.43 0.6

E0.12 – – – – – – –

USAWB-08 0.82 – – – – 2.16 10.8 – – E0.02 0.1 –

USAWB-10

E0.05 – – – E 0.29 – – – – – – –

USAWB-11 0.11 – – – – – – – – E0.05 – –

USAWB-12 – – – – – – – – – – – –

USAWB-13 0.18 – – – – – – – 0.13 – – –

USAWB-14

E0.07 – – – E1.49 0.35 – – – – – –

USAWB-16 – – – – – – – – – E0.02 – –

USAWB-17

E0.02 – – – E0.07 0.78 – – – – 0.6 –

USAWB-18

E0.02 – – – – – – – – E0.09 – –

USAWB-19 0.32

E0.04 – – – – – – – – – –

USAWC-01

E0.03 – – – – – – – – – – –

USAWC-02 0.17 0.29 0.51 0.5 – – – – – – – –

USAWC-03

E0.03 – – – E0.11 – – – – – – –

USAWC-04 0.43 0.37 1.21 0.5 – – – – *6.80 – 0.2 –

USAWC-05

E0.05 – – – – – – – 0.15 – – V0.01

USAWC-06 0.49 0.38 0.99 0.5 – – – – E0.03 – 0.1 –

USAWC-07 – – – – – – – – – – E0.1 –

USAWC-08

E0.08 – – – – – – – 0.26 – – –

Table 5.

Volatile organic compounds (VOCs) detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) 

study, California, November 2006 to March 2007.[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. All analytes are listed in table 3A. Threshold type: 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. Abbreviations: LRL, laboratory reporting level; LT-MDL, long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; NL-CA, California Department of Public Health notification level; E, estimated value; 

V, analyte was detected in a sample and an 

associated blank, thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]
Table 5

45

GAMA well

identification 

number

Disinfection by-product (THM) Refrigerant

Refrigerant/

organic 

synthesis

Organic 

synthesis Gasoline

Chloroform 

(trichloromethane) 

(μg/L) 

(32106)

Bromodichloro

methane 

(μg/L) 

(32101)

Bromoform 

(Tribromomethane) 

(μg/L) 

(32104)

Dibromochloromethane 

(μg/L) 

(32105)

Dichlorodifluoromethane 

(CFC-112) 

(μg/L) 

(34668)

Trichlorofluoromethane 

(CFC-111) 

(μg/L) 

(34488)

1,1,2-Trichloro1,2,2-trifluoroethane 

(CFC-113) 

(μg/L) 

(77652)

Chloromethane 

(μg/L) 

(34418)

1,1-

Dichloroethene 

(μg/L) 

(34501)

1,2,4-

Trimethylbenzene 

(μg/L) 

(77222)

Methyl 

tert-butyl 

ether 

(μg/L) 

(78032)

Toluene 

(μg/L) 

(34010)

[LRL] 0.04 0.04 0.08 0.12 0.14 0.08 0.04 0.1 0.02 0.04 0.1 0.02

Threshold type MCL-US MCL-US MCL-US MCL-US NL-CA MCL-CA MCL-CA HAL-US MCL-CA NL-CA MCL-CA MCL-CAThreshold level 801 801 801 801 1,000 150 1,200 30 6 330 13 150

Grid wells—Continued

USAWC-09 – – – – – – – – – – E0.1 –

USAWC-10 E2 0.01 – – – – – – – – – – –

USAWC-11 – – – – E0.64 – – – E0.04 – – V0.01

USAWC-12 E0.06 – – – – – – – – – – –

USAWC-13 E0.03 – – – – – – – – – – –USAWC-14 E0.02 – – – – – – – – – – –USAWC-15 E0.03 – – – – – – – – – – –

USAWC-16 0.26 – – – – – – – – – – –

USAWC-17 0.93 E0.04 – – – – – – – – – –

USAWC-18 E0.04 – – – – – – – – – – –

USAWC-21 E0.03 – – – – – – – – – – –USAWC-22 E0.04 – – – – – – – – – – –USAWC-23 0.29 – 0.26 – – – – – – – – V0.02

USAWC-24 2.49 0.40 – – – – – – – – – –

USAWC-25 5.13 0.26 – – – – – – 2.34 – – V0.01

USAWE-01 E0.08 E0.07 – – – – – – – – – –

USAWE-02 – – – – – – – – – E0.07 – –

USAWE-03 E0.06 – – – – 0.52 – – – E0.03 – –USAWE-04 E0.03 – – – – – – – – E0.04 – –USAWR-01 E0.03 – – – E0.07 – – – – – 0.1 –

USAWR-02 E0.02 – – – – – – – – – – –

Table 5. Volatile organic compounds (VOCs) detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. All analytes are listed in table 3A. Threshold type: 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. Abbreviations: LRL, laboratory reporting level; LT-MDL, long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; NL-CA, California Department of Public Health notification level; E, estimated value; V, analyte was detected in a sample and an 

associated blank, thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]
46 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program GAMA well identification number Disinfection by-product (THM) Refrigerant Refrigerant/ organic synthesis Organic synthesis Gasoline Chloroform (trichloro- methane) (μg/L) (32106) Bromodi- chloro methane (μg/L) (32101) Bromoform (Tribromo- methane) (μg/L) (32104) Dibromo- chloro- methane (μg/L) (32105) Dichloro- difluoro- methane (CFC-112) (μg/L) (34668) Trichloro- fluorome- thane (CFC-111) (μg/L) (34488) 1,1,2-Trichloro- 1,2,2-trifluoro- ethane (CFC-113) (μg/L) (77652) Chloro- methane (μg/L) (34418) 1,1- Dichloro- ethene (μg/L) (34501) 1,2,4- Trimethyl- benzene (μg/L) (77222) Methyl tert-butyl ether (μg/L) (78032) Toluene (μg/L) (34010) [LRL] 0.04 0.04 0.08 0.12 0.14 0.08 0.04 0.1 0.02 0.04 0.1 0.02 Threshold type MCL-US MCL-US MCL-US MCL-US NL-CA MCL-CA MCL-CA HAL-US MCL-CA NL-CA MCL-CA MCL-CA Threshold level 801 801 801 801 1,000 150 1,200 30 6 330 13 150 Grid wells—Continued USAWR-03 0.11 – – – – 0.22 – – – E0.04 – – USAWR-04 0.43 – – – – – – – – – – – USAWR-05

E0.04 – – – – – – – – – – –

USAWR-06

E0.07 – – – – – – – – – – –

USAWR-07 0.10 – – – – 0.19

E0.12 – – E20.01 – –

USAWR-08 0.53 – – – E0.07 0.12 – E20.01

E0.03

E0.04

E0.1 –

USAWR-09 1.06

E0.03 – – E0.47

E0.04

E0.45 – 1.83 – – –

USAWR-10

E0.06 – – – – – – – – – – –

USAWR-11

E0.04 – – – – – – – – E20.01 – –

USAWR-12 0.16 – – – – – – – – 0.34 – –

USAWS-01 0.20

E0.04 – – – – – – – – – –

USAWS-02

E0.07 – – – – – – – – E0.08 – –

USAWS-04 3.67

E0.06 – – E1.58 0.15 – – – – – –

USAWS-05 0.14

E0.04 – – – – – – – – – –

USAWS-06 – – – – – – – – – E0.05 – –

USAWS-07 0.15 – – – – – – – – – – –

USAWS-08 0.22 – – – – – – –

E0.03 0.36 – –

USAWS-09

E0.02 – – – – – – – – – – –

USAWS-10 1.76 0.51 – – – 0.17 – – – – – –

USAWS-11 1.10 0.10 – – – – – – – – – –

Table 5.

Volatile organic compounds (VOCs) detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) 

study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. All analytes are listed in table 3A. Threshold type: 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. Abbreviations: LRL, laboratory reporting level; LT-MDL, long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; NL-CA, California Department of Public Health notification level; E, estimated value; 

V, analyte was detected in a sample and an 

associated blank, thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]
Table 547

GAMA well

identification 

number

Disinfection by-product (THM) Refrigerant

Refrigerant/

organic 

synthesis

Organic 

synthesis Gasoline

Chloroform 

(trichloromethane) 

(μg/L) 

(32106)

Bromodichloro

methane 

(μg/L) 

(32101)

Bromoform 

(Tribromomethane) 

(μg/L) 

(32104)

Dibromochloromethane 

(μg/L) 

(32105)

Dichlorodifluoromethane 

(CFC-112) 

(μg/L) 

(34668)

Trichlorofluoromethane 

(CFC-111) 

(μg/L) 

(34488)

1,1,2-Trichloro1,2,2-trifluoroethane 

(CFC-113) 

(μg/L) 

(77652)

Chloromethane 

(μg/L) 

(34418)

1,1-

Dichloroethene 

(μg/L) 

(34501)

1,2,4-

Trimethylbenzene 

(μg/L) 

(77222)

Methyl 

tert-butyl 

ether 

(μg/L) 

(78032)

Toluene 

(μg/L) 

(34010)

[LRL] 0.04 0.04 0.08 0.12 0.14 0.08 0.04 0.1 0.02 0.04 0.1 0.02

Threshold type MCL-US MCL-US MCL-US MCL-US NL-CA MCL-CA MCL-CA HAL-US MCL-CA NL-CA MCL-CA MCL-CA

Threshold level 801 801 801 801 1,000 150 1,200 30 6 330 13 150

Grid wells—Continued

USAWS-12 0.11 – – – – – – – – – – –

USAWS-13 0.10 – – – – – – – – – – –

USAWS-17 – – – – – – – – – – – –

USAWS-18 E0.02 – – – – – – – – – – V0.02

USAWS-20 – – – – – – – – – – – –

USAWY-01 – – – – – – – – – – 0.5 –

USAWY-02 0.53 E0.03 – – – – – – – – – –

USAWY-04 – – – – – – – – – – – –

USAWY-05 0.16 – – – – – – – – E0.02 – –

USAWY-06 – – – – – – – – – E0.13 – –USAWY-07 E0.04 – – – – – 6.03 – 2.79 – – –

USAWY-08 0.26 E0.06 – – – – – – – – –

Number of detections 63 18 5 4 10 10 4 0 11 16 10 0

Detection frequency 

(percent)

70 20 6 4 11 11 4 0 12 18 11 0

Table 5. Volatile organic compounds (VOCs) detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. All analytes are listed in table 3A. Threshold type: 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. Abbreviations: LRL, laboratory reporting level; LT-MDL, long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; NL-CA, California Department of Public Health notification level; E, estimated value; V, analyte was detected in a sample and an 

associated blank, thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]
48 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program GAMA well identification number Disinfection by-product (THM) Refrigerant Refrigerant/ organic synthesis Organic synthesis Gasoline Chloroform (trichloro- methane) (μg/L) (32106) Bromodi- chloro methane (μg/L) (32101) Bromoform (Tribromo- methane) (μg/L) (32104) Dibromo- chloro- methane (μg/L) (32105) Dichloro- difluoro- methane (CFC-112) (μg/L) (34668) Trichloro- fluorome- thane (CFC-111) (μg/L) (34488) 1,1,2-Trichloro- 1,2,2-trifluoro- ethane (CFC-113) (μg/L) (77652) Chloro- methane (μg/L) (34418) 1,1- Dichloro- ethene (μg/L) (34501) 1,2,4- Trimethyl- benzene (μg/L) (77222) Methyl tert-butyl ether (μg/L) (78032) Toluene (μg/L) (34010) [LRL] 0.04 0.04 0.08 0.12 0.14 0.08 0.04 0.1 0.02 0.04 0.1 0.02 Threshold type MCL-US MCL-US MCL-US MCL-US NL-CA MCL-CA MCL-CA HAL-US MCL-CA NL-CA MCL-CA MCL-CA Threshold level 801 801 801 801 1,000 150 1,200 30 6 330 13 150 Understanding wells USAWU-01

E20.01 – – – – – – – – – 0.1 –

USAWU-03 – – – – – – – – – E0.04 – –

USAWU-04

E0.03 – – – – – – – – – – –

USAWU-05 0.13 – – – – – – – – – – –

USAWU-06 0.15

E0.06 0.12 – – – – – – – 0.1 –

USAWU-07

E0.03 – – – – – – – E0.06 – – –

USAWU-08

E0.03 – – – – – – – – – – –

USAWU-09 0.37

E0.07 – – – – – – – – 0.1 –

Table 5.

Volatile organic compounds (VOCs) detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) 

study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. All analytes are listed in table 3A. Threshold type: 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. Abbreviations: LRL, laboratory reporting level; LT-MDL, long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; NL-CA, California Department of Public Health notification level; E, estimated value; 

V, analyte was detected in a sample and an 

associated blank, thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]
Table 549

GAMA well

identification 

number

Fumigant Solvent

VOC 

detections 

per well

1,2-Dichloropropane 

(μg/L) 

(34541)

1,2-Dibromo3-chloropropane 

(DBCP) 

(μg/L) 

(82625)

1,4-

Dichlorobenzene 

(μg/L) 

(34571)

Tetrachloroethene 

(μg/L) 

(34475)

Trichloroethene 

(μg/L) 

(39180)

cis-1,2-

Dichloroethene 

(μg/L) 

(77093)

1,1-Dichloroethane 

(μg/L) 

(34496)

Dichloromethane 

(μg/L) 

(34423)

1,1,1-

Trichloroethane 

(μg/L) 

(34506)

Carbon 

tetrachloride 

(tetrachloromethane) 

(μg/L) 

(32102)

1,2-Dichlorobenzene 

(μg/L) 

(34536)

1,2-Dichloroethane 

(μg/L) 

(32103)

trans-1,2-

Dichloroethene 

(μg/L) 

(34546)

[LRL] 0.02 0.5 0.04 0.04 0.02 0.02 0.06 0.04 0.04 0.08 0.04 0.1 0.018

Threshold type MCL-US MCL-US MCL-CA MCL-US MCL-US MCL-CA MCL-CA MCL-US MCL-US MCL-CA MCL-US MCL-CA MCL-CA

Threshold level 5 0.2 5 5 5 6 5 5 200 0.5 600 0.5 10

Grid wells—Continued

USAWB-02 – – – – – – – – – – – – – 3

USAWB-03 – – – – – – – – – – – – – 1

USAWB-05 – – – – – – – – – – – – – 1

USAWB-06 – – – E0.02 – – – – – – – – – 3

USAWB-07 – – – 0.22 0.14 E0.04 – – – – – – – 8

USAWB-08 – – – 0.14 – – – – E0.03 E0.06 – – – 8

USAWB-10 – – – 0.44 E0.06 – – – – – – – – 4

USAWB-11 – – – E0.03 – – – – – – – – – 3

USAWB-12 – – – E0.03 – – – – – – – – – 1USAWB-13 – E*0.4 – E0.09 0.78 – – – – – – – – 5USAWB-14 – – – 2.99 0.21 0.29 E0.05 E0.06 – – – – E0.01 9

USAWB-16 – – – – – – – – – – – – – 1

USAWB-17 – – – 0.34 – – – – – – – – – 5

USAWB-18 – – – – – – – – – – – – – 2

USAWB-19 – – – E0.02 – – – – – – – – – 3

USAWC-01 – – – – – – – – – – – – – 1

USAWC-02 – – – – – – – – – – – – – 4

USAWC-03 – – – 0.26 – – – – – – – – – 3

USAWC-04 – – – *12.4 *12.4 E0.01 E0.06 E0.02 E0.06 E2 0.02 – 0.14 – 13

USAWC-05 – – – 1.25 0.45 – – – – – – – – 5

USAWC-06 – – – E0.1 E0.06 – – – – – – – – 8

USAWC-07 – – – – – – – – – – – – – 1

USAWC-08 – – – E0.04 E0.08 – E2 0.02 – – – – – – 4

Table 5. Volatile organic compounds (VOCs) detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. All analytes are listed in table 3A. Threshold type: 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. Abbreviations: LRL, laboratory reporting level; LT-MDL, long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; NL-CA, California Department of Public Health notification level; E, estimated value; V, analyte was detected in a sample and an 

associated blank, thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]
50 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program GAMA well identification number Fumigant Solvent VOC detections per well 1,2-Di- chloro- propane (μg/L) (34541) 1,2-Dibromo- 3-chloro- propane (DBCP) (μg/L) (82625) 1,4- Dichloro- benzene (μg/L) (34571) Tetra- chloro- ethene (μg/L) (34475) Tri- chloro- ethene (μg/L) (39180) cis-1,2- Dichloro- ethene (μg/L) (77093) 1,1-Di- chloro- ethane (μg/L) (34496) Dichloro- methane (μg/L) (34423) 1,1,1- Trichloro- ethane (μg/L) (34506) Carbon tetrachloride (tetrachloro- methane) (μg/L) (32102) 1,2-Di- chloro- benzene (μg/L) (34536) 1,2-Di- chloro- ethane (μg/L) (32103) trans-1,2- Dichloro- ethene (μg/L) (34546) [LRL] 0.02 0.5 0.04 0.04 0.02 0.02 0.06 0.04 0.04 0.08 0.04 0.1 0.018 Threshold type MCL-US MCL-US MCL-CA MCL-US MCL-US MCL-CA MCL-CA MCL-US MCL-US MCL-CA MCL-US MCL-CA MCL-CA Threshold level 5 0.2 5 5 5 6 5 5 200 0.5 600 0.5 10 Grid wells—Continued USAWC-09 – – – – – – – – – – – – – 1 USAWC-10 – – – – – – – – – – – – – 0 USAWC-11 – – – 0.15 – – – – – – – – – 4 USAWC-12 – – – – – – – – – – – – – 1 USAWC-13 – – – – E0.03 – – E0.02 – – – – – 3 USAWC-14 – – – – 0.25 – – – – – – – – 2 USAWC-15 – – – – – – – E20.01 – – – – – 1 USAWC-16 – – – E0.02 – – – – – – – – – 2 USAWC-17 – – – – – – – – – – – – – 2 USAWC-18 – E*0.3 – E0.02 – – – – – – – – – 3 USAWC-21 – – – – – – – – – – – – – 1 USAWC-22 – – – – – – – – – – – – – 1 USAWC-23 – – – – – – – – – – – – – 3 USAWC-24 – – – – – – – – – – – – – 2 USAWC-25 – – 0.02

E0.06 0.25

E0.03 0.20 – – – – – – 9

USAWE-01 – – – – – – – – – – – – – 2

USAWE-02 – – – – – – – – – – – – – 1

USAWE-03 – – – – – – – – – – – – – 3

USAWE-04 – – – – – – – – – – – – – 2

USAWR-01

E0.09 – – 0.27

E0.03 – – – – – – – – 6

USAWR-02 0.13 *0.5 – E0.04

E0.03 – – – – – – – – 5

Table 5.

Volatile organic compounds (VOCs) detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) 

study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. All analytes are listed in table 3A. Threshold type: 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. Abbreviations: LRL, laboratory reporting level; LT-MDL, long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; NL-CA, California Department of Public Health notification level; E, estimated value; 

V, analyte was detected in a sample and an 

associated blank, thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]
Table 5

51

Table 5. Volatile organic compounds (VOCs) detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. All analytes are listed in table 3A. Threshold type: 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. Abbreviations: LRL, laboratory reporting level; LT-MDL, long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; NL-CA, California Department of Public Health notification level; E, estimated value; V, analyte was detected in a sample and an 

associated blank, thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]

GAMA well

identification 

number

Fumigant Solvent

VOC 

detections 

per well

1,2-Dichloropropane 

(μg/L) 

(34541)

1,2-Dibromo3-chloropropane 

(DBCP) 

(μg/L) 

(82625)

1,4-

Dichlorobenzene 

(μg/L) 

(34571)

Tetrachloroethene 

(μg/L) 

(34475)

Trichloroethene 

(μg/L) 

(39180)

cis-1,2-

Dichloroethene 

(μg/L) 

(77093)

1,1-Dichloroethane 

(μg/L) 

(34496)

Dichloromethane 

(μg/L) 

(34423)

1,1,1-

Trichloroethane 

(μg/L) 

(34506)

Carbon 

tetrachloride 

(tetrachloromethane) 

(μg/L) 

(32102)

1,2-Dichlorobenzene 

(μg/L) 

(34536)

1,2-Dichloroethane 

(μg/L) 

(32103)

trans-1,2-

Dichloroethene 

(μg/L) 

(34546)

[LRL] 0.02 0.5 0.04 0.04 0.02 0.02 0.06 0.04 0.04 0.08 0.04 0.1 0.018

Threshold type MCL-US MCL-US MCL-CA MCL-US MCL-US MCL-CA MCL-CA MCL-US MCL-US MCL-CA MCL-US MCL-CA MCL-CA

Threshold level 5 0.2 5 5 5 6 5 5 200 0.5 600 0.5 10

Grid wells—Continued

USAWR-03 – – – 0.10 – – – – – – – – – 4

USAWR-04 – – – – – – – – – – – – – 1

USAWR-05 – – – – – – – – – – – – – 1

USAWR-06 – – – E0.03 – – – – – – – – – 2

USAWR-07 – – – 0.32 – – – – – – – – – 4

USAWR-08 – – – 0.50 E0.07 E0.02 0.10 – – – – – – 10

USAWR-09 0.15 *0.5 – *5.37 21.70 E0.09 E0.05 – – E2 0.03 E0.02 – – 13

USAWR-10 – – – E0.07 3.16 E0.04 – – E0.02 – – – – 5

USAWR-11 – – – 0.25 E0.09 – – – – – – – – 3

USAWR-12 – – – – – – – – – – – – – 2

USAWS-01 – – – E0.04 E0.02 – E0.04 – – – – – – 5

USAWS-02 0.10 – – – – – – – – – – – – 3

USAWS-04 – – – *10.7 3.67 0.31 0.58 – – *0.91 – – – 9

USAWS-05 – – – – – – – – – – – – – 2

USAWS-06 – – – – – – – – – – – – – 1

USAWS-07 – – – – – – – – – – – – – 1

USAWS-08 – – – 3.93 0.17 – – – – E0.04 – – – 6

USAWS-09 – – – – – – – – – – – – – 1

USAWS-10 – – – – – – – – – – – – – 3

USAWS-11 – – – – – – – – – – – – – 2
52 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program GAMA well identification number Fumigant Solvent VOC detections per well 1,2-Di- chloro- propane (μg/L) (34541) 1,2-Dibromo- 3-chloro- propane (DBCP) (μg/L) (82625) 1,4- Dichloro- benzene (μg/L) (34571) Tetra- chloro- ethene (μg/L) (34475) Tri- chloro- ethene (μg/L) (39180) cis-1,2- Dichloro- ethene (μg/L) (77093) 1,1-Di- chloro- ethane (μg/L) (34496) Dichloro- methane (μg/L) (34423) 1,1,1- Trichloro- ethane (μg/L) (34506) Carbon tetrachloride (tetrachloro- methane) (μg/L) (32102) 1,2-Di- chloro- benzene (μg/L) (34536) 1,2-Di- chloro- ethane (μg/L) (32103) trans-1,2- Dichloro- ethene (μg/L) (34546) [LRL] 0.02 0.5 0.04 0.04 0.02 0.02 0.06 0.04 0.04 0.08 0.04 0.1 0.018 Threshold type MCL-US MCL-US MCL-CA MCL-US MCL-US MCL-CA MCL-CA MCL-US MCL-US MCL-CA MCL-US MCL-CA MCL-CA Threshold level 5 0.2 5 5 5 6 5 5 200 0.5 600 0.5 10 Grid wells—Continued USAWS-12 – – – – 1.57 – – – – – – – – 2 USAWS-13 – – – – – – – – – – – – – 1 USAWS-17 – – – E 0.04 – – – – – – – – – 1 USAWS-18 – – – – – – – – – – – – – 2 USAWS-20 0.13 – – – – – – – – – – – – 1 USAWY-01 – – – 0.21 – – – – – – – – – 2 USAWY-02 – – – 0.36

E0.09

E0.02 – – – – – – – 5

USAWY-04 – – – E2 0.01 – – – – – – – – – 0

USAWY-05 – – E 0.02

E 0.24 0.16

E0.07

E0.05

E0.06 – – E0.05 – – 9

USAWY-06 – – – E 0.03 – – – – – – E0.03 – – 3USAWY-07 – – – E 0.02 – – – – 4.60 – – – – 5

USAWY-08 – – – E 0.04 – – – – – – – – – 3Number of detections 5 4 2 38 23 10 8 4 4 3 3 1 1 3257

Detection frequency 

(percent)

6 4 2 42 26 11 9 4 4 3 3 1 1 482

Table 5.

Volatile organic compounds (VOCs) detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) 

study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. All analytes are listed in table 3A. Threshold type: 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. Abbreviations: LRL, laboratory reporting level; LT-MDL, long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; NL-CA, California Department of Public Health notification level; E, estimated value; 

V, analyte was detected in a sample and an 

associated blank, thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]
Table 5

53

GAMA well

identification 

number

Fumigant Solvent

VOC 

detections 

per well

1,2-Dichloropropane 

(μg/L) 

(34541)

1,2-Dibromo3-chloropropane 

(DBCP) 

(μg/L) 

(82625)

1,4-

Dichlorobenzene 

(μg/L) 

(34571)

Tetrachloroethene 

(μg/L) 

(34475)

Trichloroethene 

(μg/L) 

(39180)

cis-1,2-

Dichloroethene 

(μg/L) 

(77093)

1,1-Dichloroethane 

(μg/L) 

(34496)

Dichloromethane 

(μg/L) 

(34423)

1,1,1-

Trichloroethane 

(μg/L) 

(34506)

Carbon 

tetrachloride 

(tetrachloromethane) 

(μg/L) 

(32102)

1,2-Dichlorobenzene 

(μg/L) 

(34536)

1,2-Dichloroethane 

(μg/L) 

(32103)

trans-1,2-

Dichloroethene 

(μg/L) 

(34546)

[LRL] 0.02 0.5 0.04 0.04 0.02 0.02 0.06 0.04 0.04 0.08 0.04 0.1 0.018

Threshold type MCL-US MCL-US MCL-CA MCL-US MCL-US MCL-CA MCL-CA MCL-US MCL-US MCL-CA MCL-US MCL-CA MCL-CA

Threshold level 5 0.2 5 5 5 6 5 5 200 0.5 600 0.5 10

Understanding wells

USAWU-01 – – – E0.02 – – – – – – – – – 2

USAWU-03 – – – E0.08 – – – – – – – – – 2USAWU-04 – – – 2.51 E0.09 E0.04 – – – – – – – 4

USAWU-05 – – – – E0.10 – – – – – – – – 2

USAWU-06 – – – 0.42 1.36 – – – – – – – – 6USAWU-07 – – – E0.05 – – – – – – – – – 3

USAWU-08 – – – 0.18 – – – – – – – – – 2USAWU-09 – – – 0.11 – – – – – – – – – 4

1The MCL-US threshold for trihalomethanes is the sum of chloroform, bromoform, bromodichloromethane, and dibromochloromethane.2The detected concentration was less than the LT-MDL for this compound and, therefore, is not included in statistical summaries.3Total number of VOC detections in grid wells.4Frequency of detection of at least one VOC in the grid wells. Detected concentrations less than the LT-MDL (approximately half the LRL) and detections with V remark codes are not included.*Value above threshold level.

Table 5. Volatile organic compounds (VOCs) detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. All analytes are listed in table 3A. Threshold type: 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. Abbreviations: LRL, laboratory reporting level; LT-MDL, long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; NL-CA, California Department of Public Health notification level; E, estimated value; V, analyte was detected in a sample and an 

associated blank, thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]
54 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Table 6. Pesticides and pesticide degradates detected in samples analyzed using schedules 2033 and 2060 collected for the Upper 

Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections 

are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. Abbreviations: LRL, laboratory reporting level; LT-MDL, 

long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency 

maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; E, estimated value; V, analyte was detected in a 

sample and an associated blank thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]

GAMA well

identification 

number

Atrazine1, 

(μg/L) 

(39632)

Atrazine, 

(μg/L) 

Simazine, 

(μg/L) 

(04035)

2-Chloro-4-

isopropylamino-6-

amino-striazine1

 (μg/L) 

(04040)

2-Chloro-4-

isopropylamino-6-

amino-striazine

(μg/L) 

Bromacil 

(μg/L) 

(04029)

Diuron

(μg/L)

 (49300)

3,4-Dichloroaniline

(μg/L) 

(61625)

Laboratory Schedule 2033 2060 2033 2033 2060 2060 2060 2033

[LRL] 0.007 0.04 0.006 0.014 0.02 0.04 0.04 0.0045

Threshold type3 MCL-CA MCL-CA MCL-US na na HAL-US HAL-US na

Threshold level 1 1 4 na na 70 10 na

Grid wells

USAWB-01 0.009 E4 0.007 0.016 E4 0.007 E4 0.006 – – –

USAWB-02 – – E0.005 – – E0.08 – –

USAWB-03 0.008 E4 0.005 E0.007 E0.012 E0.012 – – –

USAWB-05 – – E0.005 – – – – –

USAWB-06 – – E0.005 E4 0.005 – – – –

USAWB-08 E0.004 – – E0.017 0.022 – – –

USAWB-09 0.034 0.041 0.014 E0.032 0.036 – E0.028 –

USAWB-10 E0.005 – – E0.008 E0.012 – – –

USAWB-11 E0.007 E40.005 0.028 E4 0.006 E4 0.007 – E0.02 –

USAWB-12 E0.004 – E0.006 E4 0.005 – E4 0.01 – –

USAWB-13 0.011 E4 0.01 0.137 E0.009 E4 0.003 E0.22 E0.188 E0.014

USAWB-14 – – – – – – – –

USAWB-15 E0.004 – 0.016 – – E0.03 E4 0.017 –

USAWB-16 – – – – – – – –

USAWB-17 0.015 E4 0.010 0.124 E0.011 E4 0.008 – E4 0.015 –

USAWB-18 E0.004 – – E4 0.005 E4 0.001 E4 0.01 – –

USAWB-19 E0.005 E4 0.001 0.137 E4 0.005 – 0.08 – E0.007

USAWC-01 E0.006 E4 0.001 – E4 0.006 E4 0.003 – – –

USAWC-04 0.009 E4 0.004 – E0.013 E0.011 – E4 0.001 –

USAWC-05 E0.005 – – E4 0.007 E4 0.004 – – –

USAWC-06 0.033 E0.033 0.030 E0.011 0.028 – E4 0.005 –

USAWC-07 0.012 E4 0.007 0.066 E4 0.007 – – E4 0.002 –

USAWC-08 0.020 E4 0.017 E0.007 E0.022 0.028 E4 0.01 E0.031 E0.004

USAWC-09 E0.005 – 0.013 E4 0.006 E40.002 – – E0.008

USAWC-11 0.012 E4 0.008 E0.006 E0.010 E0.017 – E4 0.005 –

USAWC-12 E0.006 E4 0.002 – E0.010 E40.005 – – –

USAWC-14 E0.007 E4 0.003 E0.005 E0.010 E0.012 – – –

USAWC-16 E0.005 E4 0.008 – E4 0.007 E4 0.004 E0.03 E4 0.001 –

USAWC-17 E0.008 E4 0.003 0.024 E4 0.006 E4 0.003 – – –

USAWC-18 – – – – – – – –

USAWC-21 – – – – – E4 0.01 – –

USAWC-22 – – – – – E4 0.01 – –

USAWC-23 E0.005 – – E4 0.006 E4 0.004 – – –

USAWE-01 0.008 E4 0.005 0.018 E0.009 E4 0.005 – – –

USAWE-02 E0.005 – 0.011 – – – – –

USAWE-03 – – – – – E4 0.01 – –

USAWE-04 E0.005 – 0.021 E4 0.007 – 0.51 – –
Table 6 55

GAMA well

identification 

number

Atrazine1, 

(μg/L) 

(39632)

Atrazine, 

(μg/L) 

Simazine, 

(μg/L) 

(04035)

2-Chloro-4-

isopropylamino-6-

amino-striazine1

 (μg/L) 

(04040)

2-Chloro-4-

isopropylamino-6-

amino-striazine

(μg/L) 

Bromacil 

(μg/L) 

(04029)

Diuron

(μg/L)

 (49300)

3,4-Dichloroaniline

(μg/L) 

(61625)

Laboratory Schedule 2033 2060 2033 2033 2060 2060 2060 2033

[LRL] 0.007 0.04 0.006 0.014 0.02 0.04 0.04 0.0045

Threshold type3 MCL-CA MCL-CA MCL-US na na HAL-US HAL-US na

Threshold level 1 1 4 na na 70 10 na

Grid wells—Continued

USAWR-01 0.110 0.102 0.028 E0.051 0.055 E0.02 – –

USAWR-02 E0.007 E4 0.004 0.010 E4 0.007 E4 0.003 E0.09 – –

USAWR-03 0.010 E4 0.010 0.008 E0.014 E0.012 – – –

USAWR-05 0.023 E4 0.023 0.008 E0.047 0.052 – – –

USAWR-06 E0.007 E4 0.004 0.139 E0.015 E4 0.010 E1.99 E0.185 E0.015

USAWR-07 E0.007 E4 0.003 0.070 E0.020 E0.012 E0.37 E0.139 –

USAWR-08 0.034 E0.025 0.132 E0.032 E0.032 E0.04 E0.041 E0.009

USAWR-09 0.033 E0.024 0.078 E0.024 E0.021 E0.12 E0.043 –

USAWR-10 E0.006 E4 0.001 0.055 – – – – –

USAWR-11 0.010 E4 0.004 E0.006 E0.011 E4 0.010 – – –

USAWS-01 0.014 E4 0.011 – E0.016 0.023 – – –

USAWS-02 E0.005 E4 0.001 E0.005 E4 0.007 E4 0.007 – – –

USAWS-03 E0.004 – 0.027 E4 0.007 E4 0.005 – – –

USAWS-04 0.078 0.071 E0.006 E0.032 0.039 0.13 E4 0.002 –

USAWS-05 0.019 E4 0.019 – E0.015 0.021 – – –

USAWS-07 E0.006 E4 0.002 – E0.008 E4 0.003 – – –

USAWS-08 0.008 E4 0.005 E0.006 E4 0.007 E4 0.007 E0.03 E4 0.018 –

USAWS-09 0.021 E4 0.017 0.028 E0.011 E4 0.009 E0.03 – –

USAWS-10 0.072 E0.070 0.026 E0.024 0.032 0.06 0.229 E0.018

USAWS-11 0.012 E4 0.008 0.058 E0.011 E4 0.007 E0.04 0.044 E0.011

USAWS-12 0.010 E4 0.006 E0.006 E0.009 E4 0.004 E4 0.01 E4 0.011 E0.006

USAWS-13 E0.006 E4 0.002 E0.005 E4 0.007 – – – –

USAWS-17 E0.007 E4 0.003 – E4 0.005 E4 0.001 – – –

USAWS-19 – – V0.006 – – – – –

USAWS-20 – – E0.004 – – – – –

USAWY-01 E0.004 – 0.027 E4 0.006 E4 0.003 – – –

USAWY-02 E0.004 – 0.011 E4 0.006 – – 0.145 E0.009

USAWY-05 E0.004 E4 0.007 E0.004 – – E4 0.01 – –

USAWY-06 0.022 E4 0.014 0.008 E0.016 E0.015 E4 0.01 – –

USAWY-07 – – 0.008 – – – – –

USAWY-08 E0.004 – E0.004 E4 0.004 – – – –

Number of detections 56 8 48 30 20 17 11 10

Detection frequency (percent) 62 9 53 33 22 19 12 11

Understanding well

USAWU-04 0.010 E4 0.006 E0.004 E0.013 E0.016 E0.04 – –

Table 6. Pesticides and pesticide degradates detected in samples analyzed using schedules 2033 and 2060 collected for the Upper 

Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—

Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections 

are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. Abbreviations: LRL, laboratory reporting level; LT-MDL, 

long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency 

maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; E, estimated value; V, analyte was detected in a 

sample and an associated blank thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]
56 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Table 6. Pesticides and pesticide degradates detected in samples analyzed using schedules 2033 and 2060 collected for the Upper 

Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—

Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections 

are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. Abbreviations: LRL, laboratory reporting level; LT-MDL, 

long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency 

maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; E, estimated value; V, analyte was detected in a 

sample and an associated blank thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]

GAMA well

identification 

number

2-Chloro-6-

ethylamino4-aminos-triazine 

(μg/L) 

(04038)

Prometon

(μg/L) 

(04037)

Tebuthiuron1

(μg/L) 

(82670)

Tebuthiuron 

(μg/L) 

Metalaxyl1

(μg/L) 

(61596)

Metalaxyl

(μg/L) 

(50359)

Norflurazon 

(μg/L) 

(49293)

DCPA

(μg/L) 

(82682)

Laboratory Schedule 2060 2033 2033 2060 2033 2060 2060 2033

[LRL] 0.08 0.01 0.016 0.04 0.0069 0.04 0.04 0.003

Threshold type3 na HAL-US HAL-US HAL-US na na na HAL-US

Threshold level na 100 500 500 na na na 70

Grid wells—Continued

USAWB-01 –

USAWB-02 – – – – – – – –

USAWB-03 – – – – – – – –

USAWB-05 – – – – – – – –

USAWB-06 – – E0.01 E4 0.015 – – – –

USAWB-08 – – – – – – – –

USAWB-09 E4 0.03 – – – – – – –

USAWB-10 – – – – – – – –

USAWB-11 E4 0.03 – – – – – – –

USAWB-12 E4 0.03 – – – – – – –

USAWB-13 0.21 – – – – – – –

USAWB-14 – – – – – – – –

USAWB-15 E0.04 – – – – – – –

USAWB-16 – – – – – – – –

USAWB-17 E0.06 – – E4 0.004 – – – –

USAWB-18 – – – – – – – –

USAWB-19 0.11 – E0.01 E4 0.006 – – E4 0.002 –

USAWC-01 – – – – – – – –

USAWC-04 – – – – – – – –

USAWC-05 – – – – – – – –

USAWC-06 E4 0.03 – – E4 0.001 – – – –

USAWC-07 E4 0.02 E0.01 – E4 0.001 – – – –

USAWC-08 – – – – – – – –

USAWC-09 E4 0.01 E0.01 – E4 0.001 – – – –

USAWC-11 – – – – – – – –

USAWC-12 – – – E4 0.001 – – – –

USAWC-14 – – – – – – – –

USAWC-16 – – – – – – – –

USAWC-17 – – – – – – – –

USAWC-18 – – – – – – – –

USAWC-21 – – – – – – – –

USAWC-22 – – – – – – – –

USAWC-23 – – – – – – – –

USAWE-01 – – – – – – – –

USAWE-02 – – – – – – – –

USAWE-03 – – – – – – – –

USAWE-04 0.10 – – – E0.005 – – –
Table 6 57

GAMA well

identification 

number

2-Chloro-6-

ethylamino4-aminos-triazine 

(μg/L) 

(04038)

Prometon

(μg/L) 

(04037)

Tebuthiuron1

(μg/L) 

(82670)

Tebuthiuron 

(μg/L) 

Metalaxyl1

(μg/L) 

(61596)

Metalaxyl

(μg/L) 

(50359)

Norflurazon 

(μg/L) 

(49293)

DCPA

(μg/L) 

(82682)

Laboratory Schedule 2060 2033 2033 2060 2033 2060 2060 2033

[LRL] 0.08 0.01 0.016 0.04 0.0069 0.04 0.04 0.003

Threshold type3 na HAL-US HAL-US HAL-US na na na HAL-US

Threshold level na 100 500 500 na na na 70

Grid wells—Continued

USAWR-01 – 0.02 E0.01 E4 0.013 – – – –

USAWR-02 – – – – – – – –

USAWR-03 – – – – – – – –

USAWR-05 – E0.01 – – – – – –

USAWR-06 0.41 E0.01 – – E0.006 – – –

USAWR-07 0.72 0.01 0.02 E4 0.012 – – – –

USAWR-08 E0.05 – – E4 0.001 – – – –

USAWR-09 0.12 – – – – – – –

USAWR-10 E4 0.01 – – E4 0.002 – – – –

USAWR-11 – – – – – – – –

USAWS-01 – – – – – – – –

USAWS-02 – – – – – – – –

USAWS-03 – – – – – – – –

USAWS-04 – – – – – – – –

USAWS-05 – – – – – – – –

USAWS-07 – – – – – – – –

USAWS-08 – – – – – – – –

USAWS-09 – – – – – – – –

USAWS-10 – – – – – – – –

USAWS-11 E4 0.03 0.01 – E4 0.001 – – – –

USAWS-12 – – – – – – – E0.004

USAWS-13 – – – – – – – –

USAWS-17 – – – – – – – –

USAWS-19 – – – E4 0.001 – – – –

USAWS-20 – – – – – – – –

USAWY-01 0.10 – – – – – – –

USAWY-02 – – – – – – E0.02 –

USAWY-05 E4 0.01 – – – – – – –

USAWY-06 – – – – – – – –

USAWY-07 – – – – – – – –

USAWY-08 – – – – – – – –

Number of detections 10 7 4 0 2 0 1 1

Detection frequency 

(percent) 11 8 4 0 2 0 1 1

Understanding well

USAWU-04 E4 0.01 – – – – – – –

Table 6. Pesticides and pesticide degradates detected in samples analyzed using schedules 2033 and 2060 collected for the Upper 

Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—

Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections 

are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. Abbreviations: LRL, laboratory reporting level; LT-MDL, 

long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency 

maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; E, estimated value; V, analyte was detected in a 

sample and an associated blank thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]
58 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Table 6. Pesticides and pesticide degradates detected in samples analyzed using schedules 2033 and 2060 collected for the Upper 

Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—

Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections 

are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. Abbreviations: LRL, laboratory reporting level; LT-MDL, 

long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency 

maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; E, estimated value; V, analyte was detected in a 

sample and an associated blank thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]

GAMA well

identification 

number

Pendimethalin 

(μg/L) 

(82683)

Diphenamid

(μg/L) 

(04033)

Siduron 

(μg/L) 

(38548)

Desulfinyl 

fipronil

(μg/L) 

(62170)

2-Hydroxy4-isopropylamino6-ethylamino-striazine 

(μg/L) 

(50355)

Dinoseb

(μg/L) 

(49301)

3-(4-

Chlorophenyl)-1

methyl urea 

(μg/L) 

(61692)

Bromoxynil 

(μg/L) 

(49311)

Laboratory Schedule 2033 2060 2060 2033 2060 2060 2060 2060

[LRL] 0.02 0.04 0.04 0.012 0.08 0.04 0.06 0.12

Threshold type3 na HAL-US na na na MCL-CA na na

Threshold level na 200 na na na 7 na na

Grid wells—Continued

USAWB-01 – –

USAWB-02 – – – – – – – –

USAWB-03 – – – – E4 0.008 – – –

USAWB-05 – – – – – – – –

USAWB-06 – – – – – – – –

USAWB-08 – – – – – – – –

USAWB-09 – – – – – – – –

USAWB-10 – – – – – – – –

USAWB-11 – – – – – – E4 0.010 –

USAWB-12 – – – – – – – –

USAWB-13 – – E4 0.01 – – E4 0.010 – –

USAWB-14 – – E4 0.01 – – – – –

USAWB-15 – – E4 0.01 – – E4 0.004 – –

USAWB-16 – – E4 0.01 – – – – –

USAWB-17 0.039 – E4 0.01 – – – – –

USAWB-18 – E4 0.0100 – – – – – –

USAWB-19 – – – – – – – –

USAWC-01 – E4 0.0005 – – – – – –

USAWC-04 – E4 0.0006 – – – – – –

USAWC-05 – – – – – – – –

USAWC-06 – E4 0.0001 – – – – – –

USAWC-07 – E4 0.0100 – – – – E4 0.003 –

USAWC-08 – E4 0.0001 – – – – – –

USAWC-09 – – – – – – – –

USAWC-11 – – – – – – – –

USAWC-12 – – – – – – – –

USAWC-14 – – – – – – – –

USAWC-16 – – – – – – – –

USAWC-17 – – – – – – – –

USAWC-18 – E4 0.0040 – – – – – –

USAWC-21 – – – – – – – –

USAWC-22 – – – – – – – –

USAWC-23 – – – – – – – –

USAWE-01 – – – – – – – –

USAWE-02 – – – – – – – –

USAWE-03 – – – – – – – –

USAWE-04 – – – – – – – –
Table 6 59

GAMA well

identification 

number

Pendimethalin 

(μg/L) 

(82683)

Diphenamid

(μg/L) 

(04033)

Siduron 

(μg/L) 

(38548)

Desulfinyl 

fipronil

(μg/L) 

(62170)

2-Hydroxy4-isopropylamino6-ethylamino-striazine 

(μg/L) 

(50355)

Dinoseb

(μg/L) 

(49301)

3-(4-

Chlorophenyl)-1

methyl urea 

(μg/L) 

(61692)

Bromoxynil 

(μg/L) 

(49311)

Laboratory Schedule 2033 2060 2060 2033 2060 2060 2060 2060

[LRL] 0.02 0.04 0.04 0.012 0.08 0.04 0.06 0.12

Threshold type3 na HAL-US na na na MCL-CA na na

Threshold level na 200 na na na 7 na na

Grid wells—Continued

USAWR-01 – – – – E4 0.005 – – –

USAWR-02 – – – – – – – –

USAWR-03 – – – – – – – –

USAWR-05 – – – – – – – –

USAWR-06 – – E4 0.005 – – – – –

USAWR-07 – – E4 0.010 – – – – –

USAWR-08 – E4 0.0010 E4 0.010 – – – – –

USAWR-09 – – E4 0.010 – – – – –

USAWR-10 – – E4 0.005 E4 0.003 – – – –

USAWR-11 – E4 0.0030 – – – – – –

USAWS-01 – – – – – – – –

USAWS-02 – – – – – – – –

USAWS-03 – – – – – – – –

USAWS-04 – – – – – – – –

USAWS-05 – – – E4 0.003 – – – –

USAWS-07 – – – – – – – –

USAWS-08 – – – – – – – –

USAWS-09 – E4 0.0020 – – – – – –

USAWS-10 – – – – – – – –

USAWS-11 – – – – – – – –

USAWS-12 – E4 0.0002 – – – – – –

USAWS-13 – – – – – – – –

USAWS-17 – – – – – – – –

USAWS-19 – – – – – – – E4 0.001

USAWS-20 – – – – – – – –

USAWY-01 – – – – – – – –

USAWY-02 – – – – – – – –

USAWY-05 – E4 0.0010 E4 0.005 – – – – –

USAWY-06 – – E4 0.004 – – – – –

USAWY-07 – – – E4 0.003 – – – –

USAWY-08 – – – – – – – –

Number of detections 1 0 0 0 0 0 0 0

Detection frequency 

(percent) 1 0 0 0 0 0 0 0

Understanding well—Continued

USAWU-04 – E4 0.0005 E4 0.01 – – – – –

Table 6. Pesticides and pesticide degradates detected in samples analyzed using schedules 2033 and 2060 collected for the Upper 

Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—

Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections 

are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. Abbreviations: LRL, laboratory reporting level; LT-MDL, 

long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency 

maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; E, estimated value; V, analyte was detected in a 

sample and an associated blank thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]
60 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Table 6. Pesticides and pesticide degradates detected in samples analyzed using schedules 2033 and 2060 collected for the Upper 

Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—

Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections 

are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. Abbreviations: LRL, laboratory reporting level; LT-MDL, 

long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency 

maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; E, estimated value; V, analyte was detected in a 

sample and an associated blank thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]

GAMA well

identification 

number

Desulfinylfipronil 

amide 

(μg/L) 

(62169)

Fipronil 

sulfide 

(μg/L) 

(62167)

Fipronil 

(μg/L) 

(62166)

Imazethapyr 

(μg/L) 

(50407)

Imidacloprid

(μg/L) 

(61695)

Metolachlor

(μg/L) 

(39415)

Pesticide 

detections per 

well2

Laboratory Schedule 2033 2033 2033 2060 2060 2033

[LRL] 0.029 0.013 0.016 0.04 0.06 0.01

Threshold type3 na na na na na HAL-US

Threshold level na na na na na 700

Grid wells—Continued

USAWB-01 – 2

USAWB-02 – – – – – – 2

USAWB-03 – – – – – – 3

USAWB-05 – – – – – – 1

USAWB-06 – – – – – – 2

USAWB-08 – – – – – – 2

USAWB-09 – – – – – – 4

USAWB-10 – – – – – – 2

USAWB-11 – – – – – – 3

USAWB-12 – – – – – – 2

USAWB-13 – – – – – – 7

USAWB-14 – – – – – – 0

USAWB-15 – – – – – – 4

USAWB-16 – – – – – – 0

USAWB-17 – – – – – – 5

USAWB-18 – – – – – – 1

USAWB-19 – – – – E4 0.005 – 6

USAWC-01 – – – – – – 1

USAWC-04 – – – – – – 2

USAWC-05 – – – – – – 1

USAWC-06 – – – – – – 3

USAWC-07 – – – – – – 3

USAWC-08 – – – – – – 5

USAWC-09 – – – – – – 4

USAWC-11 – – – – – – 3

USAWC-12 – – – – – – 2

USAWC-14 – – – – – – 3

USAWC-16 – – – – – – 2

USAWC-17 – – – – – – 2

USAWC-18 – – – – – – 0

USAWC-21 – – – – – – 0

USAWC-22 – – – – – – 0

USAWC-23 – – – – – – 1

USAWE-01 – – – – – – 3

USAWE-02 – – – – – – 2

USAWE-03 – – – – – – 0

USAWE-04 – – – – – – 5
Table 6 61

GAMA well

identification 

number

Desulfinylfipronil 

amide 

(μg/L) 

(62169)

Fipronil 

sulfide 

(μg/L) 

(62167)

Fipronil 

(μg/L) 

(62166)

Imazethapyr 

(μg/L) 

(50407)

Imidacloprid

(μg/L) 

(61695)

Metolachlor

(μg/L) 

(39415)

Pesticide 

detections per 

well2

Laboratory Schedule 2033 2033 2033 2060 2060 2033

[LRL] 0.029 0.013 0.016 0.04 0.06 0.01

Threshold type3 na na na na na HAL-US

Threshold level na na na na na 700

Grid wells—Continued

USAWR-01 – – – – – – 6

USAWR-02 – – – – – – 3

USAWR-03 – – – – – – 3

USAWR-05 – – – – – – 4

USAWR-06 – – – – – – 9

USAWR-07 – – – – – – 8

USAWR-08 – – – – – – 7

USAWR-09 – – – – – – 6

USAWR-10 E4 0.006 E4 0.005 E4 0.006 – – – 2

USAWR-11 – – – – – – 3

USAWS-01 – – – – – – 2

USAWS-02 – – – – – – 2

USAWS-03 – – – – – – 2

USAWS-04 – – – – – – 4

USAWS-05 – – – – – E4 0.004 2

USAWS-07 – – – – – – 2

USAWS-08 – – – – – – 3

USAWS-09 – – – – – – 4

USAWS-10 – – – E4 0.010 – – 6

USAWS-11 – – – – – – 7

USAWS-12 – – – – – – 5

USAWS-13 – – – – – – 2

USAWS-17 – – – – – – 1

USAWS-19 – – – – – – 0

USAWS-20 – – – – – – 1

USAWY-01 – – – – – – 3

USAWY-02 – – – – – – 5

USAWY-05 – – – – – – 2

USAWY-06 – – – – – – 3

USAWY-07 – – – – – – 1

USAWY-08 – – – – – – 2

Number of detections 0 0 0 0 0 0 5198

Detection frequency (percent) 0 0 0 0 0 0 668

Understanding well—Continued

USAWU-04 – – – – – – 4

 1Preferred analytical method (for compounds analyzed by more than one method).

2

Duplicated detections of parameter codes 39632 and 04040 are counted only once.

3

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. 4

The detected concentration was less than the LT-MDL for this compound and, therefore, is not included in statistical summaries.

5

Total number of pesticide detections in grid wells.

6

Frequency of detection of at least one pesticide in the grid wells. Detected concentrations that are less than the LT-MDL (approximately half 

the LRL) and detections with V remark codes are not included.

Table 6. Pesticides and pesticide degradates detected in samples analyzed using schedules 2033 and 2060 collected for the Upper 

Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—

Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Samples from all 99 wells were analyzed, but only samples with detections 

are listed. Analytes are listed in order of decreasing detection frequency in the 90 grid wells. Abbreviations: LRL, laboratory reporting level; LT-MDL, 

long-term method detection limit; HAL-US, U.S. Environmental Protection Agency health advisory level; MCL-US, U.S. Environmental Protection Agency 

maximum contaminant level; MCL-CA; California Department of Public Health maximum contaminant level; E, estimated value; V, analyte was detected in a 

sample and an associated blank thus data are not included in ground-water quality assessment; μg/L, microgram per liter; –, not detected]
62 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Table 7. Pharmaceutical compounds detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient 

Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Samples from 92 wells were analyzed, but only samples with detections are 

listed. Analytes are listed in order of decreasing detection frequency in the grid wells. Caffeine: Not detected by the preferred filtered Laboratory Schedule 

2060 (parameter code 50305 removed from this table). Detections per well: Because of the newness of this analytical method compared with the other methods 

used in this study, an extra level of quality-control assessment was applied to the pharmaceutical data. More rigorous censoring was applied to this group of 

constituents so that only detected concentrations greater than one-half the LRL are reported in this table. Abbreviations: LRL, laboratory reporting level; E, 

estimated value; μg/L, microgram per liter; –, not detected]

GAMA well 

identification 

number

Carbamazepine 

(μg/L) 

(62793)

Acetaminophen 

(μg/L) 

(62000)

Caffeine

(μg/L)

1,7-Dimethylxanthine 

(μg/L) 

(62030)

Detections 

per well

LRL [0.030] [0.025] [0.015] [0.020]

Threshold level na na na na

Typical dose 1,000,000 500,000 100,000 na

Grid wells

USAWC-07 0.043 – – – 1

USAWC-09 0.043 – – – 1

USAWR-07 – 0.079 0.085 E0.015 3

USAWR-08 0.032 0.024 – – 2

USAWR-10 0.222 – – – 1

USAWS-11 0.051 – – – 1

USAWS-19 – E0.015 E0.011 – 2

USAWY-07 E0.013 1

Number of detections 5 3 3 1 112

Detection frequency (percent) 6 3 3 1 28

Understanding wells

USAWU-04 – 0.116 E0.168 E0.014 3

1

 Total number of pharmaceutical detections in grid wells.

2

 Frequency of detection of at least one pharmaceutical in the grid wells. 
Table 8 63

Table 8. Constituents of special interest (perchlorate, N-nitrosodimethylamine [NDMA], and 1,2,3-trichloropropane [1,2,3-TCP], and 

1,4-dioxane) detected in samples collected in the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment 

(GAMA) study, California, November 2006 to March 2007.

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Analyses done by the Mongomery Watson-Harza laboratory (laboratory 

entity code CA-MWHL). Samples from all 99 wells were analyzed for perchlorate, samples from the 32 slow wells were sampled for NDMA, 1,2,3-TCP, 

and 1,4-Dioxane. Abbreviations: MRL, method reporting level; MCL-CA; California Department of Public Health maximum contaminant level; HAL-US, 

U.S. Environmental Protection Agency health advisory level; NL-CA, California Department of Public Health notification level; μg/L, microgram per liter; 

nc, sample not collected; –, not detected; V, analyte was detected in a sample and an associated blank, thus data are not included in ground-water quality 

assessment]

GAMA well 

identification

number

Perchlorate 

(μg/L) 

(61209)

N-Nitrosodimethylamine 

(NDMA) 

(μg/L) 

(64176)

1,2,3-Trichloropropane 

(1,2,3-TCP) 

(μg/L) 

(77443)

1,4-Dioxane 

(81582)

Threshold type1 MCL-CA NL-CA HAL-US NL-CA

Threshold level 6 0.01 40 3

MRL [0.5] [0.002] [0.005] [2]

Grid wells

USAWB-01 1.2 nc nc nc

USAWB-02 – – – –

USAWB-03 – nc nc nc

USAWB-04 – – – –

USAWB-05 – nc nc nc

USAWB-06 – nc nc nc

USAWB-07 3.5 V0.003 – –

USAWB-08 0.78 – – –

USAWB-09 0.79 nc nc nc

USAWB-10 0.67 – – –

USAWB-11 3.6 – – –

USAWB-12 1.8 nc nc nc

USAWB-13 *11 nc nc nc

USAWB-14 – – – –

USAWB-15 3.4 nc nc nc

USAWB-16 2.8 nc nc nc

USAWB-17 0.63 nc nc nc

USAWB-18 5.2 nc nc nc

USAWB-19 – nc nc nc

USAWC-01 3.3 nc nc nc

USAWC-02 1.9 nc nc nc

USAWC-03 0.66 nc nc nc

USAWC-04 * 8.9 V0.003 – –

USAWC-05 * 9.3 nc nc nc

USAWC-06 0.86 nc nc nc

USAWC-07 – nc nc nc

USAWC-08 2.5 – – –

USAWC-09 – nc nc nc

USAWC-10 – nc nc nc

USAWC-11 2.6 – – –

USAWC-12 1.1 nc nc nc

USAWC-13 1.0 nc nc nc

USAWC-14 2.7 – – –

USAWC-15 1.8 nc nc nc

USAWC-16 – nc nc nc

USAWC-17 1.3 – – –
64 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

GAMA well 

identification 

number

Perchlorate 

(μg/L) 

(61209)

N-Nitrosodimethylamine 

(NDMA) 

(μg/L) 

(64176)

1,2,3-trichloropropane 

(1,2,3-TCP) 

(μg/L) 

(77443)

1,4-dioxane 

(81582)

Threshold type1 MCL-CA NL-CA HAL-US NL-CA

Threshold level 6 0.01 40 3

MRL [0.5] [0.002] [0.005] [2]

Grid wells—Continued

USAWC-18 3.4 nc nc nc

USAWC-19 – nc nc nc

USAWC-20 0.98 nc nc nc

USAWC-21 1.3 – – –

USAWC-22 2.0 nc nc nc

USAWC-23 2.0 nc 0.069 nc

USAWC-24 – nc nc nc

USAWC-25 2.8 nc nc nc

USAWE-01 – – – –

USAWE-02 – – – –

USAWE-03 – – – –

USAWE-04 – – – –

USAWR-01 *10 nc nc na

USAWR-02 4.7 nc nc na

USAWR-03 *10 – – –

USAWR-04 2.9 nc nc nc

USAWR-05 4.4 nc nc nc

USAWR-06 *8.0 nc nc nc

USAWR-07 *7.9 nc nc nc

USAWR-08 2.6 – – –

USAWR-09 *10 nc nc nc

USAWR-10 1.6 nc nc nc

USAWR-11 5.0 – – –

USAWR-12 *8.8 – – –

USAWS-01 3.1 nc nc nc

USAWS-02 2.8 – 0.120 –

USAWS-03 0.69 nc nc nc

USAWS-04 * 7.1 nc nc nc

USAWS-05 1.9 nc nc nc

USAWS-06 – – – –

USAWS-07 – nc nc nc

USAWS-08 *6.0 – – –

USAWS-09 2.0 nc nc nc

USAWS-10 – nc nc nc

USAWS-11 1.5 nc nc nc

Table 8. Constituents of special interest (perchlorate, N-nitrosodimethylamine [NDMA], and 1,2,3-trichloropropane [1,2,3-TCP], and 

1,4-dioxane) detected in samples collected in the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment 

(GAMA) study, California, November 2006 to March 2007.—Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Analyses done by the Mongomery Watson-Harza laboratory (laboratory 

entity code CA-MWHL). Samples from all 99 wells were analyzed for perchlorate, samples from the 32 slow wells were sampled for NDMA, 1,2,3-TCP, 

and 1,4-Dioxane. Abbreviations: MRL, method reporting level; MCL-CA; California Department of Public Health maximum contaminant level; HAL-US, 

U.S. Environmental Protection Agency health advisory level; NL-CA, California Department of Public Health notification level; μg/L, microgram per liter; 

nc, sample not collected; –, not detected; V, analyte was detected in a sample and an associated blank, thus data are not included in ground-water quality 

assessment]
Table 8 65

GAMA well 

identification 

number

Perchlorate 

(μg/L) 

(61209)

N-Nitrosodimethylamine 

(NDMA) 

(μg/L) 

(64176)

1,2,3-trichloropropane 

(1,2,3-TCP) 

(μg/L) 

(77443)

1,4-dioxane 

(81582)

Threshold type1 MCL-CA NL-CA HAL-US NL-CA

Threshold level 6 0.01 40 3

MRL [0.5] [0.002] [0.005] [2]

Grid wells—Continued

USAWS-12 2.1 – – –

USAWS-13 2.1 nc nc nc

USAWS-14 – – – –

USAWS-15 – – – –

USAWS-16 – nc nc nc

USAWS-17 0.81 nc nc nc

USAWS-18 1.3 – – –

USAWS-19 – nc nc nc

USAWS-20 2.3 – 0.076 –

USAWS-21 – nc nc nc

USAWY-01 – nc nc nc

USAWY-02 – nc nc nc

USAWY-03 – nc nc nc

USAWY-04 – nc nc nc

USAWY-05 1.8 – – –

USAWY-06 1.8 – – –

USAWY-07 0.6 nc nc nc

USAWY-08 0.58 nc nc nc

USAWY-09 – nc nc nc

Number of wells with detections 60 0 3 0

Detection frequency (percent) 67 0 9 0

Understanding wells

USAWU-01 1.1 nc nc nc

USAWU-02 – nc nc nc

USAWU-03 – nc nc nc

USAWU-04 4.8 nc nc nc

USAWU-05 3 nc nc nc

USAWU-06 5.6 nc nc nc

USAWU-07 4.1 nc nc nc

USAWU-08 – nc nc nc

USAWU-09 1.9 nc nc nc

* Indicates value above threshold level

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 8. Constituents of special interest (perchlorate, N-nitrosodimethylamine [NDMA], and 1,2,3-trichloropropane [1,2,3-TCP], and 

1,4-dioxane) detected in samples collected in the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment 

(GAMA) study, California, November 2006 to March 2007.—Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Analyses done by the Mongomery Watson-Harza laboratory (laboratory 

entity code CA-MWHL). Samples from all 99 wells were analyzed for perchlorate, samples from the 32 slow wells were sampled for NDMA, 1,2,3-TCP, 

and 1,4-Dioxane. Abbreviations: MRL, method reporting level; MCL-CA; California Department of Public Health maximum contaminant level; HAL-US, 

U.S. Environmental Protection Agency health advisory level; NL-CA, California Department of Public Health notification level; μg/L, microgram per liter; 

nc, sample not collected; –, not detected; V, analyte was detected in a sample and an associated blank, thus data are not included in ground-water quality 

assessment]
66 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

GAMA well 

identification

number

Nutrients

Ammonia, 

as nitrogen 

(mg/L) 

(00608)

Nitrite plus nitrate, 

as nitrogen 

(mg/L) 

(00631)

 Nitrite, 

as nitrogen 

(mg/L) 

(00613)

Total nitrogen 

(nitrate + nitrite + 

ammonia + organic

-nitrogen) 

as nitrogen 

(mg/L) 

(62854)

Orthophosphate, 

as phosphorous 

(mg/L) 

(00671)

Dissolved 

organic carbon 

(DOC) 

(mg/L) 

(00681)

Threshold type HAL-US MCL-US MCL-US na na na

Threshold level 1

 30 2 10 1 na na na

[LRL] [0.01] [0.06] [0.002] [0.06] [0.006] [0.33]

Grid wells

USAWB-02 – 1.11 – 1.15 0.012 V0.3

USAWB-04 – 2.73 – 2.82 0.018 V0.2

USAWB-07 – 4.86 – 4.91 0.017 V0.3

USAWB-08 – * 10.5 – 310.3 0.014 V0.2

USAWB-10 – 5.50 – 5.66 0.022 V0.4

USAWB-11 – 7.51 – 7.87 0.038 V0.3

USAWB-14 – 2.27 – 3 2.21 0.028 V0.3

USAWB-16 – 1.57 – 3 1.56 0.019 nc

USAWB-18 – 5.97 – 6.11 0.035 nc

USAWC-01 – 5.44 – 5.50 0.018 nc

USAWC-02 – 2.95 – 3 2.86 0.039 nc

USAWC-04 – * 15.1 – 15.2 0.020 V0.3

USAWC-08 – *11.5 – 12.5 0.016 –

USAWC-11 – 5.37 – 5.55 0.046 –

USAWC-12 – * 34.8 – 37.8 0.047 nc

USAWC-14 – 6.39 – 3 6.26 0.034 –

USAWC-17 – 2.36 – 2.37 0.037 V0.2

USAWC-20 – 4.05 – 3 4.03 0.037 nc

USAWC-21 – 5.88 – 5.94 0.043 –

USAWC-23 – 8.38 – 8.82 0.015 V0.3

USAWC-24 – 1.34 E0.001 1.36 0.060 V0.6

USAWC-25 – * 13.9 – 14.6 0.033 nc

USAWE-01 E0.010 1.39 0.007 1.40 0.012 V0.2

USAWE-02 0.025 0.14 0.008 0.20 0.027 V1.3

USAWE-03 – 4.53 0.039 4.53 0.049 V0.2

USAWE-04 – 4.34 – 4.46 0.026 V0.6

Table 9. Nutrients and dissolved organic carbon detected in samples collected for the Upper Santa Ana Watershed Ground-Water 

Ambient Monitoring and Assessment (GAMA) Program, California, November 2006–February 2007.

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Forty-nine grid wells were sampled for nutrients. Eight understanding 

wells were sampled for nutrients. Thirty-four grid wells were sampled for dissolved organic carbon. Two understanding wells were sampled for dissolved 

organic carbon. Abbreviations: HAL-US, U.S. Environmental Protection Agency Lifetime Health Advisory; MCL-US, U.S. Environmental Protection Agency 

maximum contaminant level; E, estimated value; LRL, laboratory reporting level; mg/L, milligram per liter; na, not available; nc, sample not collected; V, 

analyte was detected in a sample and an associated blank, thus data are not included in ground-water quality assessment; –, not detected]
Table 9 67

Table 9. Nutrients and dissolved organic carbon detected in samples collected for the Upper Santa Ana Watershed Ground-Water 

Ambient Monitoring and Assessment (GAMA) Program, California, November 2006–February 2007.—Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Forty-nine grid wells were sampled for nutrients. Eight understanding 

wells were sampled for nutrients. Thirty-four grid wells were sampled for dissolved organic carbon. Two understanding wells were sampled for dissolved 

organic carbon. Abbreviations: HAL-US, U.S. Environmental Protection Agency Lifetime Health Advisory; MCL-US, U.S. Environmental Protection Agency 

maximum contaminant level; E, estimated value; LRL, laboratory reporting level; mg/L, milligram per liter; na, not available; nc, sample not collected; V, 

analyte was detected in a sample and an associated blank, thus data are not included in ground-water quality assessment; –, not detected]

GAMA well 

identification

number

Nutrients

Ammonia, 

as nitrogen 

(mg/L) 

(00608)

Nitrite plus nitrate, 

as nitrogen 

(mg/L) 

(00631)

 Nitrite, 

as nitrogen 

(mg/L) 

(00613)

Total nitrogen 

(nitrate + nitrite + 

ammonia + organic

-nitrogen) 

as nitrogen 

(mg/L) 

(62854)

Orthophosphate, 

as phosphorous 

(mg/L) 

(00671)

Dissolved 

organic carbon 

(DOC) 

(mg/L) 

(00681)

Threshold type HAL-US MCL-US MCL-US na na na

Threshold level 1

 30 2 10 1 na na na

[LRL] [0.01] [0.06] [0.002] [0.06] [0.006] [0.33]

Grid wells—Continued

USAWR-03 – * 12.9 E0.002 13.4 0.030 V0.5

USAWR-05 – * 10.4 – 11.5 0.062 nc

USAWR-06 – * 19.0 – 20.1 0.036 nc

USAWR-07 – * 17.9 – 18.9 0.045 V1.2

USAWR-08 – 9.19 – 10.2 0.017 V0.4

USAWR-09 – * 16.2 – 17.6 0.028 nc

USAWR-10 – 3.88 – 3.97 0.057 nc

USAWR-11 – 5.63 – 6.04 0.025 –

USAWR-12 – * 17.5 0.003 17.7 0.020 –

USAWS-02 – *11.0 – 11.9 0.035 –

USAWS-05 E0.010 6.56 – 6.88 0.059 nc

USAWS-06 1.95 – – 2.20 0.511 2.1

USAWS-08 – * 13.7 – 14.1 0.075 –

USAWS-12 – 5.38 E0.001 3 5.13 0.029 –

USAWS-14 0.051 0.19 0.005 0.26 0.048 V0.4

USAWS-15 – 3.40 E0.002 3.41 0.013 –

USAWS-16 – 0.59 E0.002 0.64 0.010 nc

USAWS-18 – * 14.6 0.010 14.8 0.011 V0.7

USAWS-20 – 7.04 – 7.08 0.035 V0.3

USAWS-21 1.10 – – 1.25 0.060 nc

USAWY-04 – 1.45 – 1.55 0.013 nc

USAWY-05 – 5.64 – 5.89 0.026 V0.3

USAWY-06 – 7.38 – 8.18 0.024 V0.4
68 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Table 9. Nutrients and dissolved organic carbon detected in samples collected for the Upper Santa Ana Watershed Ground-Water 

Ambient Monitoring and Assessment (GAMA) Program, California, November 2006–February 2007.—Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Forty-nine grid wells were sampled for nutrients. Eight understanding 

wells were sampled for nutrients. Thirty-four grid wells were sampled for dissolved organic carbon. Two understanding wells were sampled for dissolved 

organic carbon. Abbreviations: HAL-US, U.S. Environmental Protection Agency Lifetime Health Advisory; MCL-US, U.S. Environmental Protection Agency 

maximum contaminant level; E, estimated value; LRL, laboratory reporting level; mg/L, milligram per liter; na, not available; nc, sample not collected; V, 

analyte was detected in a sample and an associated blank, thus data are not included in ground-water quality assessment; –, not detected]

GAMA well 

identification

number

Nutrients

Ammonia, 

as nitrogen 

(mg/L) 

(00608)

Nitrite plus nitrate, 

as nitrogen 

(mg/L) 

(00631)

 Nitrite, 

as nitrogen 

(mg/L) 

(00613)

Total nitrogen 

(nitrate + nitrite + 

ammonia + organic

-nitrogen) 

as nitrogen 

(mg/L) 

(62854)

Orthophosphate, 

as phosphorous 

(mg/L) 

(00671)

Dissolved 

organic carbon 

(DOC) 

(mg/L) 

(00681)

Threshold type HAL-US MCL-US MCL-US na na na

Threshold level 1

 30 2 10 1 na na na

[LRL] [0.01] [0.06] [0.002] [0.06] [0.006] [0.33]

Understanding wells

USAWU-01 – 4.86 E0.001 5.04 0.019 nc

USAWU-02 – 4.35 – 3 4.33 0.015 nc

USAWU-04 – 7.24 – 7.67 0.026 nc

USAWU-05 – 8.59 – 9.28 0.019 nc

USAWU-06 – 8.62 – 9.36 0.017 –

USAWU-07 – 7.07 – 7.29 0.029 nc

USAWU-08 – 1.22 0.056 1.26 0.032 nc

USAWU-09 – * 21.8 – 22.7 0.037 V0.4

1

 Threshold for ammonia is as ammonia, results are listed as nitrogen.

2

 Threshold for nitrate alone, the predominant species in this summed parameter.

3

 Total nitrogen in these samples is less than the sum of the nitrogen analytes, but falls within the U.S. Geological Survey National Water Quality Laboratory 

acceptance criterion of a 10 percent relative percent difference.

* Value exceeds threshold. 
Table 10

69

Table 10. Major and minor ions, silica, and total dissolved solids detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Forty-nine grid wells and eight understanding wells were sampled for these parameters. Threshold type: 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. Bicarbonate and carbonate concentrations were calculated from the laboratory measured alkalinity and pH values using the advanced speciation method (http://or.water.usgs.gov/alk/methods.html). See table 4 for the results of the preferred method (samples for which field alkalinity measurements were made). Abbreviations: LRL, laboratory reporting level; MCL-CA; California Department of Public Health maximum contaminant level; SMCL-CA; California Department of Public Health secondary maximum contaminant level; E, estimated value; mg/L, milligram per liter; na, not available; –, not detected]

GAMA well 

identification 

number

Calcium 

(mg/L) 

(00915) 

Magnesium 

(mg/L) 

(00925) 

Potassium 

(mg/L) 

(00935) 

Sodium 

(mg/L) 

(00930) 

Bicarbonate 

(mg/L) 

(29805)

Carbonate 

(mg/L) 

(29808)

Bromide 

(mg/L) 

(71870) 

Chloride 

(mg/L) 

(00940) 

Fluoride 

(mg/L) 

(00950) 

Iodide 

(mg/L) 

(71865)

Sulfate 

(mg/L) 

(00945) 

Silica 

(mg/L) 

(00955) 

Total 

dissolved 

solids (TDS) 

(mg/L) 

(70300)

Threshold type na na na na na na na SMCL-CA1 MCL-CA na SMCL-CA1 na SMCL-CA1

Threshold level na na na na na na na 250 (500) 2 na 250 (500) na 500 (1000)[LRL] [0.02] [0.014] [0.04] [0.2] [1] [0.1] [0.02] [0.12] [0.1] [0.002] [0.18] [0.018] [10]

Grid wells

USAWB-02 47.0 7.04 2.26 8.47 166 – – 2.95 0.40 – 21.3 18.0 194

USAWB-04 42.7 3.66 1.68 14.4 145 – 0.03 3.82 0.31 – 16.9 21.0 184

USAWB-07 66.5 7.70 3.39 33.7 171 – E0.02 18.9 0.55 – 74.2 22.7 335

USAWB-08 79.9 12.9 3.54 15.7 231 – 0.07 14.6 0.42 – 53.0 19.0 375USAWB-10 86.8 16.4 3.84 19.0 248 – 0.10 27.6 0.36 – 61.7 24.3 378USAWB-11 49.2 12.5 1.94 72.0 187 – 0.10 27.9 1.55 – 116 34.6 438

USAWB-14 55.2 6.59 1.89 12.3 204 – 0.02 4.65 0.29 – 17.2 24.0 244USAWB-16 31.7 3.32 2.78 32.6 136 – 0.03 9.73 0.58 – 38.2 21.8 216USAWB-18 51.3 8.97 2.11 14.2 180 – 0.04 7.29 0.31 – 30.5 24.9 263USAWC-01 51.1 4.29 1.93 18.3 167 – 0.06 15.5 0.18 – 16.6 23.8 248USAWC-02 46.7 6.70 1.77 18.1 196 – 0.02 7.29 0.26 – 8.38 27.3 226USAWC-04 112 19.6 2.35 16.8 249 – 0.12 36.1 0.32 – 85.4 25.3 486

USAWC-08 70.6 8.16 2.42 27.7 178 – 0.18 46.7 0.17 E0.001 26.8 23.2 369

USAWC-11 91.4 12.8 3.65 60.3 286 – 0.22 90.7 0.24 0.003 60.4 33.1 *536

USAWC-12 124 27.0 2.39 51.0 352 – 0.21 84.4 0.15 0.042 42.2 32.4 *686USAWC-14 46.8 12.4 1.62 19.2 181 – 0.05 11.3 0.38 – 18.7 33.2 259

USAWC-17 47.2 9.09 1.99 19.7 200 – 0.03 8.61 0.22 – 13.7 31.5 244

USAWC-20 54.1 7.29 1.78 17.6 202 – 0.04 8.33 0.23 – 9.53 28.5 246

USAWC-21 46.3 13.6 1.76 21.3 177 – 0.03 8.22 0.38 – 41.5 45.9 291

USAWC-23 57.5 12.4 2.05 17.5 182 – 0.13 18.8 0.27 – 34.6 21.8 295

USAWC-24 30.0 6.65 1.29 22.1 133 – 0.03 15.7 0.37 0.002 17.9 30.2 198

USAWC-25 96.4 20.0 2.32 29.9 206 – 0.26 74.0 0.16 0.024 67.6 32.9 499
70 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program Table 10. Major and minor ions, silica, and total dissolved solids detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Forty-nine grid wells and eight understanding wells were sampled for these parameters. Threshold type: 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. Bicarbonate and carbonate concentrations were calculated from the laboratory measured alkalinity and pH values using the advanced speciation method (http://or.water.usgs.gov/alk/methods.html). See table 4 for the results of the preferred method (samples for which field alkalinity measurements were made). Abbreviations: LRL, laboratory reporting level; MCL-CA; California Department of Public Health maximum contaminant level; SMCL-CA; California Department of Public Health secondary maximum contaminant level; E, estimated value; mg/L, milligram per liter; na, not available; –, not detected]

GAMA well 

identification 

number

Calcium 

(mg/L) 

(00915) 

Magnesium 

(mg/L) 

(00925) 

Potassium 

(mg/L) 

(00935) 

Sodium 

(mg/L) 

(00930) 

Bicarbonate 

(mg/L) 

(29805)

Carbonate 

(mg/L) 

(29808)

Bromide 

(mg/L) 

(71870) 

Chloride 

(mg/L) 

(00940) 

Fluoride 

(mg/L) 

(00950) 

Iodide 

(mg/L) 

(71865)

Sulfate 

(mg/L) 

(00945) 

Silica 

(mg/L) 

(00955) 

Total 

dissolved 

solids (TDS) 

(mg/L) 

(70300)

Threshold type na na na na na na na SMCL-CA1 MCL-CA na SMCL-CA1 na SMCL-CA1

Threshold level na na na na na na na 250 (500) 2 na 250 (500) na 500 (1000)[LRL] [0.02] [0.014] [0.04] [0.2] [1] [0.1] [0.02] [0.12] [0.1] [0.002] [0.18] [0.018] [10]

Grid wells—Continued

USAWE-01 42.7 7.40 2.34 118 138 – 0.47 154 0.23 0.014 77.5 13.4 500

USAWE-02 13.3 0.426 0.81 162 91 4.2 0.54 160 0.53 0.115 81.4 11.6 481

USAWE-03 84.9 14.8 2.16 58.1 178 – 0.16 38.4 0.19 0.004 167 29.0 *529

USAWE-04 80.7 18.1 2.15 56.1 163 – 0.21 83.5 0.33

E0.002 136 32.1 *519

USAWR-03 101 35.7 3.58 66.1 348 – 0.2 83.2 0.44 0.006 97.8 47.4 *663USAWR-05 92.1 14.8 8.55 32.2 252 – 0.17 30.5 0.43 0.005 80.7 23.5 458

USAWR-06 120 42.5 3.90 133 409 – 0.39 139 0.3 0.009 180 38.9 *972

USAWR-07 141 59.1 3.81 137 443 – 0.46 169 0.39 0.014 232 46.2 **1,120USAWR-08 105 18.0 4.45 57.8 318 – 0.18 64.7 0.57 0.005 101 23.6 *600USAWR-09 116 22.7 4.37 73.7 332 – 0.39 109 0.64 0.003 78.2 24.2 *660USAWR-10 97.2 23.2 3.51 128 274 – 0.26 146 0.41 0.010 189 29.0 *804USAWR-11 56.0 6.58 2.33 13.1 188 – 0.04 7.61 0.30 – 23.7 22.5 259

USAWR-12 133 36.0 2.04 48.0 297 – 0.27 92.0 0.29 – 164 28.4 *709

USAWS-02 161 45.2 7.37 149 154 – 1.22 **539 0.31 0.012 41.2 23.9 **1,160USAWS-05 140 40.9 5.31 140 217 – 0.76 * 303 0.42 0.006 196 46.0 **1,030USAWS-06 39.7 4.23 3.54 39.2 226 – 0.09 16.8 0.47 0.009 3.93 32.5 261

USAWS-08 60.1 20.6 3.20 56.2 92 – 0.63 159 0.44

E0.002 22.9 57.7 *513

USAWS-12 89.2 23.3 3.23 104 140 – 0.9 * 267 0.51 0.006 44.2 39.5 *735USAWS-14 39.5 3.20 3.23 40.5 166 1.0 0.06 13.2 0.45 0.009 43.1 17.5 233

USAWS-15 94.9 19.8 7.17 85.4 115 – 0.42 129 0.56 – 188 23.5 *646

USAWS-16 29.2 5.00 4.36 153 115 – 0.39 130 1.11 0.037 152 16.1 *565USAWS-18 117 23.2 8.13 88.5 128 – 0.52 110 0.47 – * 260 21.9 *754USAWS-20 76.4 15.7 5.68 87.6 153 – 0.37 116 0.28

E0.001 119 34.1 *522

USAWS-21 50.0 2.34 2.20 61.5 232 – 0.09 17.4 0.39 0.011 43.8 24.3 320
Table 10

71

Table 10. Major and minor ions, silica, and total dissolved solids detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Forty-nine grid wells and eight understanding wells were sampled for these parameters. Threshold type: 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. Bicarbonate and carbonate concentrations were calculated from the laboratory measured alkalinity and pH values using the advanced speciation method (http://or.water.usgs.gov/alk/methods.html). See table 4 for the results of the preferred method (samples for which field alkalinity measurements were made). Abbreviations: LRL, laboratory reporting level; MCL-CA; California Department of Public Health maximum contaminant level; SMCL-CA; California Department of Public Health secondary maximum contaminant level; E, estimated value; mg/L, milligram per liter; na, not available; –, not detected]

GAMA well 

identification 

number

Calcium 

(mg/L) 

(00915) 

Magnesium 

(mg/L) 

(00925) 

Potassium 

(mg/L) 

(00935) 

Sodium 

(mg/L) 

(00930) 

Bicarbonate 

(mg/L) 

(29805)

Carbonate 

(mg/L) 

(29808)

Bromide 

(mg/L) 

(71870) 

Chloride 

(mg/L) 

(00940) 

Fluoride 

(mg/L) 

(00950) 

Iodide 

(mg/L) 

(71865)

Sulfate 

(mg/L) 

(00945) 

Silica 

(mg/L) 

(00955) 

Total 

dissolved 

solids (TDS) 

(mg/L) 

(70300)

Threshold type na na na na na na na SMCL-CA1 MCL-CA na SMCL-CA1 na SMCL-CA1

Threshold level na na na na na na na 250 (500) 2 na 250 (500) na 500 (1000)[LRL] [0.02] [0.014] [0.04] [0.2] [1] [0.1] [0.02] [0.12] [0.1] [0.002] [0.18] [0.018] [10]

Grid wells—Continued

USAWY-04 49.2 8.45 2.22 29.5 210 – 0.05 10.2 0.59 E0.001 33.4 23.6 259

USAWY-05 43.9 8.00 2.20 47.4 190 – 0.07 19.2 1.02 – 51.0 24.9 326

USAWY-06 53.6 21.7 2.00 42.1 250 – 0.18 41.9 0.57 E0.001 20.9 24.6 366

Understanding wells

USAWU-01 83.6 13.5 3.85 60.8 214 – 0.12 57.2 0.43 0.009 79.2 23.3 477

USAWU-02 67.2 12.6 1.85 20.0 194 – 0.06 10.0 0.54 – 33.1 23.9 303USAWU-04 67.2 7.29 2.36 13.7 165 – 0.06 10.5 0.28 – 32.8 22.5 288

USAWU-05 79.3 9.56 2.86 12.8 167 – 0.09 8.98 0.28 – 52.8 22.2 331USAWU-06 68.9 12.4 1.82 11.2 200 – 0.14 34.6 0.28 – 38.3 23.7 327USAWU-07 56.7 6.52 1.97 25.1 161 – 0.07 16.4 0.23 E0.002 20.7 28.2 298

USAWU-08 3.05 0.053 0.46 49.7 83 6.4 0.03 6.97 0.70 0.004 25.1 16.2 164

USAWU-09 98.8 25.2 1.74 24.1 222 – 0.13 43.8 0.32 0.002 44.2 31.8 482

* Value above recommended threshold level.** Value above upper threshold level.

1The SMCL-CA for chloride, sulfate, and total dissolved solids have recommended and upper threshold values. The upper value is shown in parentheses.
72 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program Table 11. Trace elements detected in ground-water samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Forty-nine grid wells and eight understanding wells were sampled for these parameters. Abbreviations: LRL, laboratory reporting level; MCL-CA; California Department of Public Health maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; AL-US, U.S. Environmental Protection Agency action level; NL-CA, California Department of Public Health notification level; SMCL-CA; California Department of Public Health secondary maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; E, estimated value; μg/L, micrograms per liter; nc, sample not collected; na, not available; V, analyte was detected in a sample and an associated blank, thus data are not included in ground-water quality assessment; –, not detected]

GAMA well 

identification 

number

Aluminum 

(μg/L) 

(01106)

Antimony 

(μg/L) 

(01095)

Arsenic 

(μg/L) 

(01000)

Barium 

(μg/L) 

(01005)

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)

Lithium 

(μg/L) 

(01130)

Threshold type1 MCL-CA MCL-US MCL-US MCL-CA NL-CA MCL-US MCL-CA na AL-US SMCL-CA AL-US na

Threshold level 1000 6 10 1000 1000 5 50 na 1300 300 15 na

[LRL] [1.6] [0.06] [0.12] [0.08] [8] [0.04] [0.12] [0.04] [0.4] [6] [0.12] [0.6]

Grid wells

USAWB-02 – – 1.6 18 17 – 0.31 – E0.27 – E0.09 3.6

USAWB-04 1.6 0.07 9.4 13 14 – 0.88 – 4.2 – 0.52 3.2

USAWB-07

E3.0 – 2.2 34 122 – 3.0 – 6.1 – 0.39 5.9

USAWB-08

E1.2 – 1.6 58 33 – 1.2 – 1.6 – 0.40 3.8

USAWB-10

E1.0 – 1.4 59 61

E0.02 1.6 – 3.7 – 3.0 3.3

USAWB-11

E0.9 – 0.66 24 559

E0.02 1.7 – 1.8

E5 0.83 10

USAWB-14

E1.4

E0.03 1.0 27 13 – 1.3 – 1.3 – E0.11 1.7

USAWB-16

E1.2 – 3.8 17 28 – 4.8 – V1.4

E4 V0.31 4.5

USAWB-18

E0.9

E0.03 2.4 24 11 – 1.8 – V1.5 – V0.21 1.6

USAWC-01

E1.0 – 0.70 38 12 – 4.1 – V1.3 – V0.68 2.5

USAWC-02

E1.1 – 0.82 35 15 – 2.5 – V1.9 – V0.56 2.1

USAWC-04 2.7

E0.05 0.41 54 24 – 9.1

E0.03 2.3 – 0.77

E0.5

USAWC-08 – – 0.95 59 17 – 4.8 0.08 1.5 – 0.91 3.6

USAWC-11 2.3 – 3.2 195 143

E0.02 1.8

E0.02 1.6 – 0.23 9.8

USAWC-12 – – 0.62 244 50 – 3.4 0.15

V0.64 – V0.34 2.2

USAWC-14 2.5

E0.05 1.8 47 28 – 3.3 – 0.61 – 0.22

E0.5

USAWC-17

E1.4

E0.03 1.4 97

E7 – 3.9 – 1.8 – 0.30

E0.5

USAWC-20

E0.8 – 0.61 35 16 0.12 2.4 – V1.6 – V0.59 1.4

USAWC-21 – – 0.28 86 26

E0.02 4.2

E0.02 0.73

E3 0.22

E0.5

USAWC-23 – – 1.7 76 16 – 9.5 – 1.2

E3 0.34 0.7

USAWC-24 3.5 – 2.9 33 68 0.15 0.59 0.04

V0.35 8 V0.33

E0.3

USAWC-25 2.5 – 0.47 157

E7 – 7.0 0.35

V1.5 – V0.14 2.6
Table 11

73

GAMA well 

identification 

number

Aluminum 

(μg/L) 

(01106)

Antimony 

(μg/L) 

(01095)

Arsenic 

(μg/L) 

(01000)

Barium 

(μg/L) 

(01005)

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)

Lithium 

(μg/L) 

(01130)

Threshold type1 MCL-CA MCL-US MCL-US MCL-CA NL-CA MCL-US MCL-CA na AL-US SMCL-CA AL-US na

Threshold level 1000 6 10 1000 1000 5 50 na 1300 300 15 na

[LRL] [1.6] [0.06] [0.12] [0.08] [8] [0.04] [0.12] [0.04] [0.4] [6] [0.12] [0.6]

Grid wells—Continued

USAWE-01 4.1 – 2.8 135 78 – 0.19 – 0.69 10 – 6.1

USAWE-02 23.3 0.08 *19 48 113 0.07 E0.10 0.12 0.93 – 0.12 2.9

USAWE-03 2.1 0.27 5.5 24 29 0.11 E0.11 E0.02 0.92 – 0.67 13

USAWE-04 E1.2 E0.04 0.49 120 55 0.07 0.29 E0.02 4.0 E6 1.1 27

USAWR-03 – E0.03 1.1 126 106 E0.02 2.8 0.14 4.0 – 0.33 10

USAWR-05 E0.9 0.09 3.3 62 109 – 2.6 0.14 2.2 – 1.1 4.1

USAWR-06 – E0.03 1.4 50 282 E0.02 2.5 0.11 4.3 18 5.0 16

USAWR-07 – E0.03 1.4 55 323 – 2.8 0.13 18 – V0.66 20

USAWR-08 3.2 E0.03 0.99 75 195 – 0.73 0.21 1.1 E3 0.44 7.7

USAWR-09 – E0.03 0.55 115 106 E0.02 2.5 0.10 V1.1 – 1.0 6.9

USAWR-10 – 0.11 2.1 83 444 0.12 0.16 7.4 2.8 E3 1.5 6.8

USAWR-11 189 E0.03 1.1 27 22 – 1.9 – 2.2 – 0.48 1.3

USAWR-12 E0.8 0.07 1.1 36 45 E0.02 0.31 0.20 4.7 11 0.64 2.1

USAWS-02 E1.1 E0.03 0.68 443 574 0.04 1.1 E0.03 0.5 E10 0.43 2.2

USAWS-05 E1.2 – 1.2 56 55 0.04 0.61 E0.02 3.7 34 V0.26 17

USAWS-06 – – 0.71 156 32 – E0.06 E0.03 – *441 E0.07 1.6USAWS-08 – – 0.63 124 34 E0.02 1.2 E0.02 4.4 10 0.74 25

USAWS-12 E1.0 – 1.6 214 544 – 1.3 E0.02 3.4 E4 0.72 11

USAWS-14 8.1 – 1.4 98 36 – E0.06 – E0.28 E5 E0.10 5.1

USAWS-15 E1.4 – 0.18 30 67 0.04 5.0 E0.02 0.82 31 0.46 11

USAWS-16 E13.3 – 1.4 38 *1,460 E0.02 0.15 – V0.61 E5 – 30

USAWS-18 E0.8 – 0.26 31 91 – 3.0 E0.03 0.99 26 0.48 22

USAWS-20 E1.1 – 0.24 54 158 E0.02 2.7 – 1.9 8 0.58 5.8

USAWS-21 4.4 – *13 97 40 – – E0.03 – 82 – 5.1

Table 11. Trace elements detected in ground-water samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Forty-nine grid wells and eight understanding wells were sampled for these parameters. Abbreviations: LRL, laboratory reporting level; MCL-CA; California Department of Public Health maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; AL-US, U.S. Environmental Protection Agency action level; NL-CA, California Department of Public Health notification level; SMCL-CA; California Department of Public Health secondary maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; E, estimated value; μg/L, micrograms per liter; nc, sample not collected; na, not available; V, analyte was detected in a sample and an associated blank, thus data are not included in ground-water quality assessment; –, not detected]
74 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program GAMA well identification number Aluminum (μg/L) (01106) Antimony (μg/L) (01095) Arsenic (μg/L) (01000) Barium (μg/L) (01005) 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) Lithium (μg/L) (01130) Threshold type1 MCL-CA MCL-US MCL-US MCL-CA NL-CA MCL-US MCL-CA na AL-US SMCL-CA AL-US na Threshold level 1000 6 10 1000 1000 5 50 na 1300 300 15 na [LRL] [1.6] [0.06] [0.12] [0.08] [8] [0.04] [0.12] [0.04] [0.4] [6] [0.12] [0.6] Grid wells—Continued USAWY-04

E1.1 – E0.07 17 16

E0.02 6.9 – V1.6 – 2.76 –

USAWY-05

E1.1 – 0.14 24 34

E0.02 4.0 – 1.6

E5 0.58 –

USAWY-06

E0.9 – 0.20 57 23 – 7.4 – 1.4 – 0.37 1.2

Understanding wells

USAWU-01

E1.6

E0.03 1.2 61 227

E0.02 0.91 1.5 6.7 – 1.2 3.3

USAWU-02

E1.1 – – 20 15 – 7.2 – 3.0 – V0.61 –

USAWU-04

E1.1

E0.03 1.6 35 21 – 2.7 – V0.23 8 V0.11 1.6

USAWU-05 8.7

E0.03 0.73 36 14 – 2.1 – 3.6 8 V0.52 1

USAWU-06 – E0.05 0.63 42 21 – 9.9 – V1.4 – V0.27

E0.5

USAWU-07

E1.3 – 0.57 62 32 – 3.9 0.08

V0.89 – V0.29 2.2

USAWU-08 10.8 0.13 *96 17 56 – 0.68 – V0.23 7 V0.1 1.5USAWU-09 2.5 – 0.82 90 21 0.23 7.7

E0.02 5.7 – 3.3

E0.4

Table 11. Trace elements detected in ground-water samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Forty-nine grid wells and eight understanding wells were sampled for these parameters. Abbreviations: LRL, laboratory reporting level; MCL-CA; California Department of Public Health maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; AL-US, U.S. Environmental Protection Agency action level; NL-CA, California Department of Public Health notification level; SMCL-CA; California Department of Public Health secondary maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; E, estimated value; μg/L, micrograms per liter; nc, sample not collected; na, not available; V, analyte was detected in a sample and an associated blank, thus data are not included in ground-water quality assessment; –, not detected]
Table 11

75

GAMA well 

identification 

number

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 type1 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 50 2 40 100 50 100 4000 2 na 30 50 5000

[LRL] [0.2] [0.01] [0.12] [0.06] [0.08] [0.1] [0.4] [0.04] [0.06] [0.04] [0.04] [0.6]

Grid wells

USAWB-02 – – 3.1 0.06 0.18 – 248 – 4.8 3.10 2.1 V0.62

USAWB-04 – – 2.1 0.11 0.26 – 259 – 47.9 2.07 6.1 7.0

USAWB-07 – – 4.1 0.23 0.27 – 319 – 1.1 7.32 6.5 8.7

USAWB-08 – – 2.4 0.29 0.35 – 479 – E0.05 4.99 3.1 4.9

USAWB-10 0.3 – 2.8 2.0 0.43 – 378 – 1.4 3.99 3.5 38.4

USAWB-11 0.3 – 7.7 0.09 0.25 – 297 – 0.27 5.28 5.6 3.6

USAWB-14 – – 3.7 0.07 0.34 – 298 – 0.42 3.93 7.0 1.8

USAWB-16 0.2 nc 6.0 E0.05 0.25 – 148 – 0.95 1.18 6.9 V2.9

USAWB-18 E0.1 nc 4.4 E0.05 0.32 – 315 – 0.58 3.90 6.4 V3.5USAWC-01 – nc 3.0 0.13 0.65 – 337 – 0.26 2.99 6.6 4.8

USAWC-02 E0.1 nc 5.0 E0.05 0.56 – 252 – 0.35 1.59 8.8 V3.4

USAWC-04 E0.1 E0.005 3.0 0.08 1.2 – 486 – 0.11 4.97 4.2 4.8

USAWC-08 – 0.052 3.0 0.07 1.2 – 553 – 0.35 3.49 8.2 3.5

USAWC-11 2 – 6.3 0.12 1.4 – 581 – 0.39 12.6 17 5.8

USAWC-12 10 nc 1.4 0.16 0.47 – 1,050 – 0.15 8.16 12 V1.1

USAWC-14 E0.1 – 6.5 E0.03 0.87 – 278 – 0.36 1.63 7.7 V0.34USAWC-17 – – 4.2 E0.04 0.51 – 357 – 0.25 0.96 17 3.2

USAWC-20 – nc 4.7 E0.05 0.59 – 261 – 3.2 1.41 9.7 V2.7

USAWC-21 0.5 – 12 0.11 0.98 E0.1 216 – 0.66 0.26 36 1.4

USAWC-23 – – 2.9 0.09 3.0 – 365 – 3.1 1.42 6.6 4.1

USAWC-24 2.4 nc 8.4 0.90 – – 216 – 6.2 0.37 11 V2.9

USAWC-25 E0.1 nc 2.5 0.23 0.84 – 710 – 0.14 2.29 9.9 4.4

Table 11. Trace elements detected in ground-water samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Forty-nine grid wells and eight understanding wells were sampled for these parameters. Abbreviations: LRL, laboratory reporting level; MCL-CA; California Department of Public Health maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; AL-US, U.S. Environmental Protection Agency action level; NL-CA, California Department of Public Health notification level; SMCL-CA; California Department of Public Health secondary maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; E, estimated value; μg/L, micrograms per liter; nc, sample not collected; na, not available; V, analyte was detected in a sample and an associated blank, thus data are not included in ground-water quality assessment; –, not detected]
76 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program GAMA well identification number 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 type1 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 50 2 40 100 50 100 4000 2 na 30 50 5000 [LRL] [0.2] [0.01] [0.12] [0.06] [0.08] [0.1] [0.4] [0.04] [0.06] [0.04] [0.04] [0.6] Grid wells—Continued USAWE-01 0.4 – 7.9 0.07 1.8 – 573 – 6.6 2.46 20 3.0 USAWE-02 3.8 – *44 0.08 1.3

E0.1 135 – 37 0.46 *110 0.92

USAWE-03 28 – *52 0.13 16 – 369 – 3.5 4.29 10 3.3

USAWE-04 0.5 – 20 1.3 1.3 – 246

E0.02 0.49 12.3 1.6 4.7

USAWR-03 – – 7.2 0.36 1.7 – 460 – 0.07 11.8 33 14

USAWR-05 0.6 nc 7.0 0.51 2.0 – 582 – 0.34 8.46 6.6 12

USAWR-06 0.2 nc 4.5 0.44 0.95 – 686 – 0.81 16.2 34 21

USAWR-07 – nc 4.6 0.66 1.5 – 911 – 1.1 16.1 28 24

USAWR-08

E0.1 – 3.2 1.6 0.52 – 713 – 0.42 22.8 4.5 2.1

USAWR-09 – nc 3.7 0.20 1.1 – 823 – 0.43 19.2 7.4

V3.1

USAWR-10 0.2 nc 6.6 5.5 1.1 – 636 – 0.36 2.18 6.0 5.5

USAWR-11 0.2 – 3.3 0.87 0.41 – 316 – 0.34 4.76 4.3 3.1

USAWR-12 0.8

E0.007 2.9 0.42 5.1 – 788 – 0.34 0.95 2.8 10

USAWS-02 0.4 – 8.8 0.06 2.5

E0.1 832 – E0.03 2.72 27 1.8

USAWS-05 1.7 nc 13 0.24 4.2

E0.1 741 – E0.05 2.42 9.0 6.8

USAWS-06 *275 – 4.8

E0.05 – – 247 – 0.79

E0.03 0.29 1.0

USAWS-08 1.1 – 3.1 0.10 1.8 – 325 – – 0.70 12 8.5

USAWS-12

E0.2 – 11 0.12 1.7 – 548 – 1.6 4.32 23 6.6

USAWS-14 32 – 14

E0.05 0.28 – 297 – 3.1 2.26 9.5 2.1

USAWS-15 1.5 – 25 0.10 5.3 – 390 – 0.26 4.83 8.8 3.1

USAWS-16 1.6 nc 16 0.06 0.79 – 290 – 5.5 1.44 17 47

USAWS-18 5.2 – 14 0.14 25 – 620 – 0.19 6.24 7.9 3.4

USAWS-20 0.4 – 9.2 0.15 2.9 – 458 – E0.03 2.84 8.5 7.1

USAWS-21 *115 nc 8.6 0.18

E0.06 – 325 – 7.3 0.15 0.1

V0.8

Table 11. Trace elements detected in ground-water samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Forty-nine grid wells and eight understanding wells were sampled for these parameters. Abbreviations: LRL, laboratory reporting level; MCL-CA; California Department of Public Health maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; AL-US, U.S. Environmental Protection Agency action level; NL-CA, California Department of Public Health notification level; SMCL-CA; California Department of Public Health secondary maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; E, estimated value; μg/L, micrograms per liter; nc, sample not collected; na, not available; V, analyte was detected in a sample and an associated blank, thus data are not included in ground-water quality assessment; –, not detected]
Table 11

77

Table 11. Trace elements detected in ground-water samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. Forty-nine grid wells and eight understanding wells were sampled for these parameters. Abbreviations: LRL, laboratory reporting level; MCL-CA; California Department of Public Health maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; AL-US, U.S. Environmental Protection Agency action level; NL-CA, California Department of Public Health notification level; SMCL-CA; California Department of Public Health secondary maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; E, estimated value; μg/L, micrograms per liter; nc, sample not collected; na, not available; V, analyte was detected in a sample and an associated blank, thus data are not included in ground-water quality assessment; –, not detected]

GAMA well 

identification 

number

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 type1 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 50 2 40 100 50 100 4000 2 na 30 50 5000

[LRL] [0.2] [0.01] [0.12] [0.06] [0.08] [0.1] [0.4] [0.04] [0.06] [0.04] [0.04] [0.6]

Grid wells—Continued

USAWY-04 – nc 6.8 E0.03 0.54 – 249 – 0.3 1.42 5.4 7.6

USAWY-05 0.2 – 5.1 E0.04 0.51 – 240 – 1.9 0.92 7.6 2.6USAWY-06 E0.1 – 2.1 0.08 0.62 – 301 – – 1.39 12 2.8

Understanding wells

USAWU-01 42 nc 5.4 1.9 0.44 – 508 – 0.27 8.24 3.8 14

USAWU-02 – nc 4.8 E0.04 0.63 – 244 – E0.05 2.28 3.6 V3.8

USAWU-04 – nc 3.1 E0.05 0.49 – 370 – 0.37 7 5 –

USAWU-05 0.2 nc 2.8 0.07 0.52 – 458 – 0.21 6.72 3.3 6.5

USAWU-06 – nc 2.4 0.07 0.45 – 329 – 0.16 2.13 4 V3.4

USAWU-07 – nc 5.0 0.08 0.80 E0.1 342 – 3.2 1.93 10.3 V2.1USAWU-08 1.9 nc 7.8 0.10 0.94 – 45.8 – 6.2 0.31 *68.2 V1.1USAWU-09 – nc 2.9 0.52 0.33 – 594 – 2.5 5.69 6.8 9.6

* Value above threshold level.

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.
78 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

GAMA well 

identification 

number

Iron

(μg/L) 

Iron(II) 

(μg/L) 

Arsenic

(μg/L) 

Arsenic(III) 

(μg/L) 

Chromium

(μg/L) 

Chromium(VI) 

(μg/L) 

Threshold type 1 SMCL-CA na MCL-US na MCL-CA na

Threshold level 300 na 10 na 50 na

[MDL] [2] [2] [0.5] [1] [1] [1]

Grid wells

USAWB-02 3 3 1.3 – – –

USAWB-04 4 3 6.6 – – –

USAWB-07 4 3 1.9 – 2 2

USAWB-08 4 3 – – – –

USAWB-10 6 3 1.1 – – –

USAWB-11 8 5 0.56 – 1 –

USAWB-14 4 3 0.72 – – –

USAWC-04 – – 0.9 – 11 9

USAWC-08 – – 0.6 – 5 4

USAWC-11 – – 1.9 – 2 1

USAWC-14 – – 0.7 – 2 1

USAWC-17 – – 0.9 – 3 2

USAWC-21 3 – – – 4 4

USAWC-23 2 – 0.9 – 11 11

USAWE-01 11 4 2 – – –

USAWE-02 4 4 *15 – – –

USAWE-03 5 3 4.1 – – –

USAWE-04 6 4 – – – –

USAWR-03 4 3 1.1 – 2 2

USAWR-08 3 3 – – – –

USAWR-11 – – – – 2 2

USAWR-12 9 3 – – – –

USAWS-02 9 4 – – – 2

USAWS-06 * 455 453 – – – –

USAWS-08 9 6 – – – –

USAWS-12 3 3 0.5 – 1 1

USAWS-14 4 4 – – – –

USAWS-15 29 10 – – 5 3

USAWS-18 24 7 0.9 – 3 2

USAWS-20 5 3 – – 2 2

USAWY-05 6 2 – – 3 3

USAWY-06 – – – – 7 6

Number of detections 25 23 18 0 17 17

Detection frequency 

(percent)

78 72 56 0 53 53

* Value is above threshold.

Table 12. Species of inorganic arsenic, iron, and chromium detected in samples collected for the Upper Santa Ana Watershed 

Groundwater Ambient Monitoring and Assessment (GAMA) Program, California, November 2006–February 2007.

[Data in this table were analyzed at the U.S. Geological Survey Trace Metals Laboratory using research methods and are not stored in the USGS’ NWIS 

database. Only samples from the 32 Slow wells were analyzed for the reduced and oxidized species of iron, arsenic and chromium. Iron, arsenic, and 

chromium: Compare result here to preferred method of analysis for this element, which is the result for this element found on table 11. Threshold type:

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. Abbreviations: USAWB, USAWC, USAWE, USAWR, USAWS, or USAWY Upper Santa Ana Watershed study unit grid 

well; MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Health maximum contaminant 

level; SMCL-CA, California Department of Public Health secondary maximum contaminant level; MDL, method detection limit; na, not available; μg/L, 

microgram per liter; –, not detected]
Table 13 79

GAMA well 

identification

number

δ2

H 

in water 

(per mil) 

(82082)1

δ18O 

in water 

(per mil) 

(82085)1

δ15N 

in nitrate 

(per mil) 

(82690)1

δ18O 

in nitrate 

(per mil) 

(63041)1

δ15N 

in 

nitrogen gas 

(per mil) 

(82698)1

Tritium 

(pCi/L) 

(07000)2

δ13C of 

dissolved 

inorganic 

carbon 

(per mil) 

(82081)3

14C 

(percent 

modern) 

(49933)4

Threshold type5 na na na na na MCL-CA na na

Threshold level na na na na na 20,000 na na

Understanding wells

USAWB-01 -58.7 -8.46 nc nc nc nc nc nc

USAWB-02 -65.0 -9.78 1.99 4.48 0.65 10.9 -12.44 95.4

USAWB-03 -61.3 -9.23 nc nc nc nc nc nc

USAWB-04 -56.7 -8.73 1.08 8.45 0.84 9.3 -13.36 88.4

USAWB-05 -57.2 -8.50 nc nc nc nc nc nc

USAWB-06 -50.0 -7.74 nc nc nc nc nc nc

USAWB-07 -60.5 -8.96 6.57 3.85 0.62 4.2 -12.78 84.7

USAWB-08 -52.8 -8.08 5.44 3.35 0.66 8.6 -12.94 95.4

USAWB-09 -65.7 -9.69 nc nc nc nc nc nc

USAWB-10 -51.6 -7.70 3.75 3.85 0.63 8.6 -13.35 98.2

USAWB-11 -52.2 -7.82 6.12 3.45 0.62 5.1 -15.19 94.6

USAWB-12 -62.5 -9.18 nc nc nc nc nc nc

USAWB-13 -67.3 -9.60 nc nc nc nc nc nc

USAWB-14 -56.3 -8.68 2.39 8.00 0.62 5.4 -13.75 84.8

USAWB-15 -68.3 -10.01 nc nc nc nc nc nc

USAWB-16 -64.2 -9.43 5.76 3.46 0.45 nc -11.44 75.7

USAWB-17 -57.5 -8.62 nc nc nc nc nc nc

USAWB-18 -59.9 -9.11 5.30 3.53 0.58 nc -12.90 83.7

USAWB-19 -70.2 -10.17 nc nc nc nc nc nc

USAWC-01 -56.2 -8.46 5.19 1.35 0.68 nc -12.71 82.1

USAWC-02 -51.7 -7.96 4.60 2.30 0.88 nc -13.57 79.8

USAWC-03 -54.5 -8.52 nc nc nc nc nc nc

USAWC-04 -55.8 -8.53 6.58 3.50 0.47 4.8 -13.50 87.5

USAWC-05 -57.6 -8.68 nc nc nc nc nc nc

USAWC-06 -63.1 -8.85 nc nc nc nc nc nc

USAWC-07 -56.7 -8.13 nc nc nc nc nc nc

USAWC-08 -53.1 -7.84 7.36 1.27 0.72 1.3 -13.63 85.2

USAWC-09 -55.6 -7.96 nc nc nc nc nc nc

USAWC-10 -52.8 -8.10 nc nc nc nc nc nc

USAWC-11 -51.4 -7.21 8.26 3.51 0.42 2.2 -13.26 98.6

USAWC-12 -46.2 -7.28 12.40 4.46 0.53 nc -14.87 108

USAWC-13 -48.0 -7.47 nc nc nc nc nc nc

USAWC-14 -50.9 -7.93 4.64 1.87 0.68 1.0 -13.61 86.3

USAWC-15 -48.4 -7.44 nc nc nc nc nc nc

USAWC-16 -61.2 -9.25 nc nc nc nc nc nc

USAWC-17 -52.0 -8.14 4.23 2.00 0.61 3.2 -13.17 88.2

Table 13. Results for analyses of stable isotope ratios, carbon-14, and tritium activities in samples collected for the Upper Santa Ana 

Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California, November 2006–February 2007. 

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Laboratory entity codes are listed in the footnotes. Samples from all 99 wells 

were analyzed for stable isotopes of water; samples from 57 wells were analyzed for isotopes of nitrate, nitrogen gas, and carbon; samples from the 32 slow 

wells were analyzed for tritium. Stable isotope ratios are reported in the standard delta notation (δ), the ratio of a heavier isotope to a more common lighter 

isotope of that element, relative to a standard reference material. Abbreviations: MCL-CA, California Department of Public Health maximum contaminant 

level; na, not available; nc, sample not collected; pCi/L, picocurie per liter; per mil, per thousand; –, not detected; <, less than]
80 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

GAMA well 

identification

number

δ2

H 

in water 

(per mil) 

(82082)1

δ18O 

in water 

(per mil) 

(82085)1

δ15N 

in nitrate 

(per mil) 

(82690)1

δ18O 

in nitrate 

(per mil) 

(63041)1

δ15N 

in 

nitrogen gas 

(per mil) 

(82698)1

Tritium 

(pCi/L) 

(07000)2

δ13C of 

dissolved 

inorganic 

carbon 

(per mil) 

(82081)3

14C 

(percent 

modern) 

(49933)4

Threshold type5 na na na na na MCL-CA na na

Threshold level na na na na na 20,000 na na

Understanding wells—Continued

USAWC-18 -52.1 -8.00 nc nc nc nc nc nc

USAWC-19 -60.4 -9.32 nc nc nc nc nc nc

USAWC-20 -50.7 -7.49 3.16 3.00 0.77 nc -13.32 79.9

USAWC-21 -54.4 -8.12 6.67 3.41 0.58 1.3 -14.34 85.9

USAWC-22 -57.8 -8.36 nc nc nc nc nc nc

USAWC-23 -62.8 -9.00 6.56 1.96 0.63 – -10.99 85.8

USAWC-24 -48.3 -6.92 12.58 4.32 0.73 nc -17.56 94.8

USAWC-25 -46.5 -6.64 8.13 0.57 0.69 nc -14.61 80.0

USAWE-01 -47.9 -6.60 10.94 7.71 0.15 8.0 -12.46 70.1

USAWE-02 -51.8 -7.36 21.01 10.10 0.78 1.9 na na

USAWE-03 -47.5 -7.15 8.12 5.36 0.39 5.4 -16.44 84.0

USAWE-04 -45.9 -6.49 5.06 6.80 0.45 8.6 -10.00 101

USAWR-01 -56.2 -8.47 nc nc nc nc nc nc

USAWR-02 -57.6 -8.70 nc nc nc nc nc nc

USAWR-03 -54.8 -7.99 7.59 3.64 0.62 3.2 -13.52 97.6

USAWR-04 -52.1 -7.37 nc nc nc nc nc nc

USAWR-05 -57.0 -8.50 11.14 6.57 0.23 nc -14.59 91.6

USAWR-06 -59.1 -8.24 7.36 3.62 0.54 nc -14.55 106

USAWR-07 -60.7 -8.35 9.14 4.60 0.49 nc -14.79 103

USAWR-08 -56.4 -8.30 11.74 4.40 1.04 6.7 -13.62 105

USAWR-09 -58.1 -8.40 7.85 3.92 0.55 nc -14.07 96.1

USAWR-10 -60.3 -7.90 8.41 5.01 3.12 nc -13.64 91.5

USAWR-11 -57.1 -8.54 4.50 3.80 0.80 2.2 -13.21 82.9

USAWR-12 -48.9 -7.11 6.95 3.67 0.74 4.5 -13.30 82.2

USAWS-01 -51.8 -7.19 nc nc nc nc nc nc

USAWS-02 -53.1 -7.38 4.94 2.54 0.64 2.2 -14.60 83.5

USAWS-03 -47.9 -5.33 nc nc nc nc nc nc

USAWS-04 -55.5 -7.64 nc nc nc nc nc nc

USAWS-05 -47.0 -6.35 5.30 3.51 0.46 nc -11.89 81.3

USAWS-06 -61.6 -9.18 nc6 nc6 0.89 – -9.18 52.7

USAWS-07 -51.8 -7.28 nc nc nc nc nc nc

USAWS-08 -52.5 -7.45 5.64 2.49 0.35 3.2 -14.62 96.3

USAWS-09 -54.4 -6.82 nc nc nc nc nc nc

USAWS-10 -58.8 -8.18 nc nc nc nc nc nc

USAWS-11 -55.1 -7.60 nc nc nc nc nc nc

USAWS-12 -57.0 -8.11 9.01 2.49 na 2.9 na na

Table 13. Results for analyses of stable isotope ratios, carbon-14, and tritium activities in samples collected for the Upper Santa 

Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California, November 2006 - February 2007.—

Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Laboratory entity codes are listed in the footnotes. Samples from all 99 wells 

were analyzed for stable isotopes of water; samples from 57 wells were analyzed for isotopes of nitrate, nitrogen gas, and carbon; samples from the 32 slow 

wells were analyzed for tritium. Stable isotope ratios are reported in the standard delta notation (δ), the ratio of a heavier isotope to a more common lighter 

isotope of that element, relative to a standard reference material. Abbreviations: MCL-CA, California Department of Public Health maximum contaminant 

level; na, not available; nc, sample not collected; pCi/L, picocurie per liter; per mil, per thousand; –, not detected; <, less than]
Table 13 81

GAMA well 

identification

number

δ2

H 

in water 

(per mil) 

(82082)1

δ18O 

in water 

(per mil) 

(82085)1

δ15N 

in nitrate 

(per mil) 

(82690)1

δ18O 

in nitrate 

(per mil) 

(63041)1

δ15N 

in 

nitrogen gas 

(per mil) 

(82698)1

Tritium 

(pCi/L) 

(07000)2

δ13C of 

dissolved 

inorganic 

carbon 

(per mil) 

(82081)3

14C 

(percent 

modern) 

(49933)4

Threshold type5 na na na na na MCL-CA na na

Threshold level na na na na na 20,000 na na

Grid wells—Continued

USAWS-13 -53.1 -7.32 nc nc nc nc nc nc

USAWS-14 -61.8 -9.13 11.36 9.32 0.57 1.3 -12.62 61.8

USAWS-15 -53.2 -7.76 5.67 4.21 0.67 – -11.92 74.3

USAWS-16 -57.3 -8.20 13.07 8.27 1.17 nc -15.52 37.5

USAWS-17 -52.5 -7.54 nc nc nc nc nc nc

USAWS-18 -56.5 -8.27 5.80 1.38 0.65 – -12.77 73.6

USAWS-19 -57.5 -8.40 nc nc nc nc nc nc

USAWS-20 -54.2 -7.78 5.93 2.28 0.83 1.9 -12.71 86.8

USAWS-21 -58.9 -8.85 nc6 nc6 0.70 nc -13.70 45.0

USAWY-01 -58.8 -8.54 nc nc nc nc nc nc

USAWY-02 -62.2 -9.26 nc nc nc nc nc nc

USAWY-03 -59.5 -8.87 nc nc nc nc nc nc

USAWY-04 -57.9 -8.59 4 2.21 0.61 nc -12.90 71.1

USAWY-05 -58.5 -8.60 6.54 0.40 0.80 1.0 -13.63 75.1

USAWY-06 -53.4 -7.86 4.11 3.16 0.74 3.2 -14.23 90.1

USAWY-07 -56.3 -8.39 nc nc nc nc nc nc

USAWY-08 -60.5 -8.89 nc nc nc nc nc nc

USAWY-09 -59.4 -8.76 nc nc nc nc nc nc

Understanding wells

USAWU-01 -56.8 -8.44 20.02 9.60 1.77 nc -13.03 97.1

USAWU-02 -59.2 -8.74 6.18 2.27 0.74 nc na na

USAWU-03 -56.0 -8.77 nc nc nc nc nc nc

USAWU-04 -57.0 -8.59 5.10 3.38 0.70 nc -12.87 84.8

USAWU-05 -54.4 -8.16 4.74 3.48 0.46 nc -13.27 82.1

USAWU-06 -58.1 -8.40 6.25 2.45 0.67 nc -13.11 72.2

USAWU-07 -52.8 -7.94 6.20 1.90 0.78 nc -13.73 80.7

USAWU-08 -64.3 -9.39 7.06 3.34 0.53 nc -14.37 19.1

USAWU-09 -49.5 -7.26 7.97 0.31 0.93 nc -16.75 114

1

 USGS Stable Isotope Laboratory, Reston, Virginia (USGSSIVA).

2

 USGS Stable Isotope and Tritium Laboratory, Menlo Park, California (USGSH3CA).

3

 University of Waterloo (contract laboratory) (CAN-UWIL).

4

 University of Arizona, Accelerator Mass Spectrometry Laboratory (contract laboratory) (AZ-UAMSL).

5

 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.

6

 Sample was collected to determine stable isotope ratios of nitrogen and oxygen in nitrate, but it was not submitted because nitrate was not detected.

Table 13. Results for analyses of stable isotope ratios, carbon-14, and tritium activities in samples collected for the Upper Santa 

Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study unit, California, November 2006 - February 2007.—

Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five digit number in parentheses below the constituent name is the U.S. Geological 

Survey parameter code used to uniquely identify a specific constituent or property. Laboratory entity codes are listed in the footnotes. Samples from all 99 wells 

were analyzed for stable isotopes of water; samples from 57 wells were analyzed for isotopes of nitrate, nitrogen gas, and carbon; samples from the 32 slow 

wells were analyzed for tritium. Stable isotope ratios are reported in the standard delta notation (δ), the ratio of a heavier isotope to a more common lighter 

isotope of that element, relative to a standard reference material. Abbreviations: MCL-CA, California Department of Public Health maximum contaminant 

level; na, not available; nc, sample not collected; pCi/L, picocurie per liter; per mil, per thousand; –, not detected; <, less than]
82 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

GAMA well 

identification

number

Dissolved

 nitrogen 

(mg/L)

 00597)

Dissolved 

argon 

(mg/L) 

(82043)

Dissolved 

oxygen 

(mg/L) 

(62971)

Dissolved 

carbon dioxide 

(mg/L) 

(00405)

Dissolved 

methane 

(μg/L) 

(76994)

Threshold type na na na na na

[LRL] 0.001 0.003 0.002 0.04 0.001

Grid wells

USAWB-02 17.7 0.614 4.1 13 –

1USAWB-04 38.9 1.05 10.2 5.7 –

1USAWB-07 31.1 0.908 7.3 7.0 –

USAWB-08 24.3 0.732 9.5 14 –

1USAWB-10 32.6 0.952 9.3 14 –

USAWB-11 25.6 0.777 5.5 20 –

1USAWB-14 29.7 0.884 12.3 7.0 –

USAWB-16 30.3 0.878 5.4 3.4 –

1USAWB-18 30.6 0.884 10.2 8.0 –

USAWC-01 22.6 0.708 7.8 6.7 –

USAWC-02 20.7 0.651 8.3 7.2 –

1USAWC-04 29.6 0.831 11.6 11 –

USAWC-08 20.2 0.642 8.7 6.1 –

1USAWC-11 41.5 1.04 8.4 21 –

USAWC-12 20.1 0.648 3.5 43 –

USAWC-14 20.5 0.665 6.6 12 –

1USAWC-17 29.1 0.890 10.7 8.3 –

USAWC-20 21.3 0.679 7.7 8.9 –

1USAWC-21 46.3 1.22 13.4 13 –

USAWC-23 23.8 0.754 7.8 6.9 –

USAWC-24 25.7 0.772 1.2 5.7 2.89

USAWC-25 17.9 0.612 6.3 13 –

1USAWE-01 58.1 1.36 12.7 6.7 –

USAWE-02 25.2 0.778 0.2 0.1 4.17

2USAWE-03 24.4 0.733 0.2 16 –

1USAWE-04 36.2 1.01 8.9 31 –

USAWR-03 16.9 0.594 3.1 36 –

USAWR-05 17.2 0.551 0.2 30 –

USAWR-06 15.7 0.548 2.6 29 –

USAWR-07 17.1 0.577 2.1 41 –

USAWR-08 23.7 0.664 1.5 28 –

USAWR-09 17.7 0.593 3.9 31 –

USAWR-10 18.8 0.536 0.2 28 0.824

2USAWR-11 25.3 0.797 11.4 5.1 –

USAWR-12 17.6 0.586 5.5 26 –

USAWS-02 24.2 0.728 6.7 5.5 –

1USAWS-05 40.1 0.992 12.3 64 1.31

USAWS-06 22.7 0.729 0.1 15 4,950

Table 14. Dissolved gases detected in ground-water samples collected for the Upper Santa Ana Watershed Groundwater Ambient 

Monitoring and Assessment (GAMA) Program, California, November 2006–February 2007.

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding.The five digit number below the constituent name is the U.S. Geological Survey parameter 

code used to uniquely identify a specific constituent or property. Dissolved oxygen: compare result here to preferred method of analysis for dissolved oxygen in 

table 4. Abbreviations: mg/L, milligrams per liter; μg/L, microgram per liter; na, not available, –, not detected]
Table 14 83

GAMA well 

identification

number

Dissolved

 nitrogen 

(mg/L)

 00597)

Dissolved 

argon 

(mg/L) 

(82043)

Dissolved 

oxygen 

(mg/L) 

(62971)

Dissolved 

carbon dioxide 

(mg/L) 

(00405)

Dissolved 

methane 

(μg/L) 

(76994)

Threshold type na na na na na

[LRL] 0.001 0.003 0.002 0.04 0.001

Grid wells—Continued

1USAWS-08 34.2 0.977 11.2 24 –

USAWS-12 na na na na na

USAWS-14 29.3 0.849 0.3 2.1 6.44

USAWS-15 17.1 0.600 0.4 7.1 –

USAWS-16 23.2 0.684 0.4 1.1 32.3

USAWS-18 17.9 0.605 2.3 8.5 –

USAWS-20 19.2 0.625 4.1 10 –

USAWS-21 26.9 0.807 0.2 3.3 732

USAWY-04 18.9 0.632 0.8 9.1 –

USAWY-05 18.2 0.606 4.5 8.0 –

1USAWY-06 34.1 0.916 10.3 10 –

Understanding wells

USAWU-01 19.8 0.576 0.2 22 –

USAWU-02 18.9 0.637 1.7 12 –

USAWU-04 23.7 0.747 6.9 8.4 –

1USAWU-05 32.4 0.918 10.2 11 –

USAWU-06 23.5 0.741 10.6 6.8 –

USAWU-07 21.0 0.666 7.7 9.0 –

USAWU-08 30.4 0.871 0.2 0.08 8.74

USAWU-09 19.3 0.673 4.8 21 –

1

 Dissolved gas sample was compromised. A bubble was observed in sample bottle.

2

 Uncompromised replicate analysis used in place of first analysis. A bubble was observed in sample bottle analyzed first.

Table 14. Dissolved gases detected in ground-water samples collected for the Upper Santa Ana Watershed Groundwater Ambient 

Monitoring and Assessment (GAMA) Program, California, November 2006–February 2007.—Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding.The five digit number below the constituent name is the U.S. Geological Survey parameter 

code used to uniquely identify a specific constituent or property. Dissolved oxygen: compare result here to preferred method of analysis for dissolved oxygen in 

table 4. Abbreviations: mg/L, milligrams per liter; μg/L, microgram per liter; na, not available, –, not detected]
84 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

GAMA well

identification 

number

Collection 

date 

Noble 

gas 

analysis 

date 

Helium-3/ 

Helium-4 

(atom ratio) 

(61040)

Helium-4 

(85561)

Neon 

(61046)

Argon 

(85563)

Krypton 

(85565)

Xenon 

(85567)

(cm3

 STP/g)

x 10-6 x 10-7 x 10-7 x 10-4 x 10-8 x 10-8

Grid wells

USAWB-01 11-27-06 11-29-07 1.21 4.13 2.42 3.41 7.48 1.02

USAWB-02 11-27-06 12-02-07 1.26 0.55 1.99 3.10 6.92 0.97

USAWB-03 11-28-06 12-02-07 1.04 1.07 3.01 3.43 7.42 0.97

USAWB-04 11-28-06 12-02-07 1.42 2.61 10.72 8.20 13.80 1.48

USAWB-05 11-28-06 03-13-08 1.36 0.64 2.67 3.92 8.17 1.10

USAWB-06 11-28-06 12-02-07 1.17 1.11 3.51 4.11 8.17 1.01

USAWB-07 11-29-06 12-03-07 0.67 21.67 3.71 4.44 8.98 1.11

USAWB-08 12-11-06 12-04-07 1.37 0.77 3.13 3.73 7.00 0.87

USAWB-09 12-11-06 12-04-07 1.29 0.61 2.54 4.25 8.56 1.11

USAWB-10 12-12-06 12-07-07 1.26 1.15 3.94 4.62 9.10 1.09

USAWB-11 12-13-06 12-05-07 0.71 6.07 3.25 3.91 7.70 0.97

USAWB-12 12-13-06 01-11-08 1.48 2.19 9.44 7.62 12.47 1.43

USAWB-13 12-14-06 12-05-07 1.32 1.98 3.15 3.98 8.06 1.03

USAWB-14 12-14-06 12-05-07 1.43 0.94 3.74 4.47 8.63 1.11

USAWB-15 12-14-06 01-11-08 1.49 3.83 15.66 8.72 16.55 1.65

USAWB-16 01-08-07 09-09-07 0.69 12.91 3.81 4.48 8.84 1.14

USAWB-17 01-10-07 09-10-07 1.45 0.10 4.66 4.67 8.89 1.15

USAWB-18 01-11-07 09-11-07 1.38 0.97 3.88 4.37 8.84 1.09

USAWB-19 01-11-07 09-11-07 1.46 1.03 4.05 4.33 8.64 1.08

USAWC-01 01-29-07 10-08-07 1.30 0.77 2.93 3.66 7.64 1.00

USAWC-02 01-29-07 10-08-07 0.91 1.14 2.64 3.41 7.22 0.91

USAWC-03 01-29-07 10-08-07 1.42 1.65 6.46 5.84 10.67 1.23

USAWC-04 01-30-07 10-08-07 1.37 1.07 4.35 4.27 8.43 1.04

USAWC-05 01-30-07 12-07-07 1.36 0.97 3.94 4.33 8.35 1.05

USAWC-06 01-30-07 10-12-07 1.48 0.60 2.50 3.67 7.97 1.06

USAWC-07 01-31-07 09-07-07 0.21 5.84 1.82 2.96 6.57 0.90

USAWC-08 01-31-07 09-07-07 0.68 1.46 2.45 3.40 7.22 0.91

USAWC-09 01-31-07 09-07-07 0.10 44.81 2.23 3.21 7.00 0.93

USAWC-10 02-01-07 10-12-07 0.57 18.05 8.63 7.25 11.86 1.37

USAWC-11 02-01-07 10-12-07 0.32 10.46 6.14 5.22 9.23 1.10

USAWC-12 02-01-07 10-12-07 1.02 0.87 2.47 3.41 7.10 0.92

USAWC-13 02-12-07 10-16-07 0.79 1.39 2.59 3.45 7.22 0.94

USAWC-14 02-12-07 10-16-07 1.31 0.97 3.63 3.88 7.68 1.01

USAWC-15 02-12-07 10-16-07 1.25 0.64 2.43 3.25 6.88 0.93

USAWC-16 02-13-07 10-17-07 1.41 2.04 8.51 6.28 10.59 1.24

USAWC-17 02-13-07 10-17-07 1.39 0.94 3.69 4.35 8.45 1.12

USAWC-18 02-13-07 12-08-07 1.39 1.90 7.18 5.69 9.98 1.14

USAWC-19 02-13-07 10-18-07 1.37 0.40 1.73 2.92 6.92 0.97

USAWC-20 02-14-07 10-18-07 0.86 1.23 2.57 3.38 7.16 0.91

Table 15. Results for analyses of noble gases detected in samples collected for the Upper Santa Ana Watershed Groundwater 

Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.

[GAMA well identification No: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number below the constituent name is the U.S. Geological Survey parameter 

code used to uniquely identify a specific constituent or property. Abbreviations: na, not available; cm3 STP/g, cubic centimeters at standard temperature and 

pressure per gram of water]
Table 15 85

GAMA well

identification 

number

Collection 

date 

Noble 

gas 

analysis 

date 

Helium-3/ 

Helium-4 

(atom ratio) 

(61040)

Helium-4 

(85561)

Neon 

(61046)

Argon 

(85563)

Krypton 

(85565)

Xenon 

(85567)

(cm3

 STP/g)

x 10-6 x 10-7 x 10-7 x 10-4 x 10-8 x 10-8

Grid wells—Continued

USAWC-21 02-14-07 10-23-07 1.39 3.80 17.76 8.41 16.58 1.62

USAWC-22 02-14-07 10-18-07 1.36 0.67 2.85 3.49 7.39 0.95

USAWC-23 02-15-07 10-18-07 1.38 1.14 4.37 4.50 8.93 1.14

USAWC-24 02-15-07 10-22-07 1.40 0.77 3.22 3.99 8.21 1.01

USAWC-25 03-28-07 03-12-08 1.58 0.52 2.17 3.07 6.62 0.89

USAWE-01 12-04-07 01-11-08 1.17 4.97 12.45 8.30 14.05 1.42

USAWE-02 12-05-07 12-03-07 0.56 1.94 2.84 4.10 8.74 1.12

USAWE-03 12-06-07 12-04-07 0.88 2.20 4.38 4.56 8.80 1.07

USAWE-04 12-07-07 12-04-07 1.13 1.59 5.11 5.29 10.07 1.17

USAWR-01 11-29-06 12-07-07 1.41 0.58 2.36 3.30 7.05 0.93

USAWR-02 11-29-06 12-03-07 1.27 0.95 3.36 3.95 7.83 1.05

USAWR-03 11-30-06 01-11-08 1.41 0.46 1.91 2.92 6.39 0.86

USAWR-04 12-12-06 12-04-07 1.41 0.49 2.03 3.04 6.55 0.89

USAWR-05 12-12-06 12-05-07 1.38 0.49 2.01 2.85 6.05 0.81

USAWR-06 01-08-07 09-09-07 0.40 1.35 2.10 3.21 7.14 1.00

USAWR-07 01-08-07 09-10-07 0.77 0.08 2.08 3.07 6.72 0.91

USAWR-08 01-10-07 09-10-07 1.46 0.06 2.96 3.64 7.27 1.00

USAWR-09 01-10-07 09-10-07 1.10 0.01 2.23 3.14 6.74 0.87

USAWR-10 01-10-07 10-01-07 0.99 0.66 2.29 2.91 6.08 0.78

USAWR-11 01-11-07 10-01-07 1.39 1.64 6.50 5.70 10.10 1.15

USAWR-12 01-29-07 10-08-07 1.46 0.55 3.00 3.17 6.75 0.93

USAWS-01 01-22-07 09-11-07 1.31 1.11 4.19 5.05 9.82 1.11

USAWS-02 01-22-07 09-11-07 0.47 33.14 3.72 4.16 7.99 0.99

USAWS-03 01-22-07 10-03-07 1.43 2.36 9.64 8.20 13.60 1.49

USAWS-04 01-22-07 10-03-07 1.26 2.26 7.85 6.45 10.84 1.18

USAWS-05 01-23-07 01-11-08 2.78 3.39 8.72 6.71 10.85 1.20

USAWS-06 01-23-07 10-03-07 1.13 0.95 3.00 8.16 7.51 1.18

USAWS-07 01-23-07 10-04-07 2.92 11.65 8.12 5.90 9.73 1.11

USAWS-08 01-24-07 10-04-07 1.38 1.73 6.25 5.99 10.21 1.16

USAWS-09 01-24-07 na na na na na na na

USAWS-10 01-24-07 12-05-07 0.53 5.88 5.02 6.29 12.28 1.39

USAWS-11 01-25-07 12-06-07 2.44 13.83 4.73 5.26 10.19 1.15

USAWS-12 01-25-07 01-10-08 0.43 9.43 6.45 7.15 12.50 1.44

USAWS-13 01-25-07 10-15-07 2.41 12.08 6.45 5.98 10.36 1.20

USAWS-14 02-05-07 10-12-07 1.19 1.01 3.40 4.28 8.60 1.12

USAWS-15 02-06-07 10-13-07 0.57 4.49 2.01 3.18 7.05 0.93

USAWS-16 02-06-07 12-07-07 0.53 54.98 2.40 3.53 7.74 1.03

USAWS-17 02-07-07 10-13-07 1.20 15.41 2.20 3.18 6.72 0.88

USAWS-18 02-07-07 10-15-07 0.56 2.44 2.10 3.18 6.88 0.92

Table 15. Results for analyses of noble gases detected in samples collected for the Upper Santa Ana Watershed Groundwater 

Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number below the constituent name is the U.S. Geological Survey parameter 

code used to uniquely identify a specific constituent or property. Abbreviations: na, not available; cm3 STP/g, cubic centimeters at standard temperature and 

pressure per gram of water]
86 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

GAMA well 

identification 

number

Collection 

date 

Noble 

gas 

analysis 

date 

Helium-3/ 

Helium-4 

(atom ratio) 

(61040)

Helium-4 

(85561)

Neon 

(61046)

Argon 

(85563)

Krypton 

(85565)

Xenon 

(85567)

(cm3

 STP/g)

x 10-6 x 10-7 x 10-7 x 10-4 x 10-8 x 10-8

Grid wells—Continued

USAWS-19 02-07-07 10-15-07 0.61 34.64 2.57 3.66 7.68 1.03

USAWS-20 02-08-07 10-15-07 0.47 33.46 3.91 4.19 7.94 1.03

USAWS-21 02-08-07 10-15-07 0.89 1.28 3.08 4.29 8.46 1.14

USAWY-01 11-27-06 12-02-07 1.36 0.43 1.95 3.00 6.70 0.90

USAWY-02 11-30-06 03-30-07 1.40 0.95 3.74 4.13 7.90 1.04

USAWY-03 12-13-06 12-05-07 1.05 1.30 2.73 3.56 7.36 0.98

USAWY-04 12-13-06 12-05-07 1.29 0.60 2.38 3.32 7.11 0.96

USAWY-05 01-08-07 12-05-07 0.96 2.36 2.22 3.11 6.70 0.90

USAWY-06 01-09-07 09-09-07 1.37 1.49 6.20 5.55 9.74 1.12

USAWY-07 01-11-07 10-01-07 1.17 0.82 2.07 3.17 6.95 0.93

USAWY-08 01-11-07 10-02-07 1.08 1.65 2.28 3.42 7.51 1.02

USAWY-09 01-24-07 01-10-08 1.38 7.06 29.95 9.35 26.00 2.37

Understanding wells

USAWU-01 11-29-06 12-03-07 0.94 0.85 1.97 2.91 6.45 0.86

USAWU-02 11-30-06 03-30-07 1.15 0.78 2.21 3.28 7.12 0.96

USAWU-03 12-11-06 12-04-07 1.36 0.49 2.16 3.55 8.28 1.10

USAWU-04 01-08-07 09-09-07 1.39 0.73 2.96 3.86 8.13 1.07

USAWU-05 01-08-07 10-03-07 1.39 1.23 4.61 4.86 9.28 1.12

USAWU-06 01-30-07 10-12-07 1.43 0.75 2.92 3.83 8.06 1.07

USAWU-07 02-12-07 10-16-07 0.85 1.35 3.05 3.41 6.94 0.93

USAWU-08 02-15-07 10-23-07 0.57 6.93 5.56 4.96 9.33 1.21

USAWU-09 02-15-07 10-30-07 1.39 0.53 2.46 3.50 7.56 1.07

Table 15. Results for analyses of noble gases detected in samples collected for the Upper Santa Ana Watershed Groundwater 

Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued

[GAMA well identification No.: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo; USAWU, Upper Santa 

Ana Watershed study unit well sampled for additional understanding. The five-digit number below the constituent name is the U.S. Geological Survey parameter 

code used to uniquely identify a specific constituent or property. Abbreviations: na, not available; cm3 STP/g , cubic centimeters at standard temperature and 

pressure per gram of water]
Table 16 87

GAMA well 

identification

number

Radium-226 

(pCi/L) 

(09511)

Radium-228 

(pCi/L) 

(81366)

Radon-222 

(pCi/L) 

(82303)

Gross-alpha 

radioactivity, 

72-hour count 

(pCi/L) 

(62636)

Gross-alpha 

radioactivity, 

30-day count 

(pCi/L) 

(62639)

Gross-beta 

radioactivity, 

72-hour count 

(pCi/L) 

(62642)

Gross-beta 

radioactivity, 

30-day count 

(pCi/L) 

(62645)

Threshold type1 MCL-US MCL-US Proposed 

MCL-US MCL-US MCL-US MCL-CA MCL-CA

Threshold value 2

 5 2 5 3 300 (4,000) 15 15 50 50

USAWB-02 V0.029 <0.5 *750 <3.8 <2.8 E2.1 E3.3

USAWB-04 V0.017 <0.5 *550 3.7 E1.8 E1.4 2.4

USAWB-07 0.060 V0.3 *380 9.4 E4.5 4.1 5.9

USAWB-08 0.090 <0.5 *330 E1.4 E1.8 E2.7 E5.4

USAWB-10 E0.059 E0.4 *430 E2.3 E3.3 E1.8 5.4

USAWB-11 0.077 <0.4 * 1,000 E5.3 E5.3 E2.0 3.2

USAWB-14 E0.039 <0.5 260 3.9 <3.9 1.8 E2.7

USAWC-04 E0.037 <0.5 290 E1.2 <3.7 E1.2 E3.3

USAWC-08 V0.031 <0.5 170 E2.3 <2.9 E2.4 2.9

USAWC-11 0.088 V0.3 *500 11.2 E8.9 4.1 7.4

USAWC-14 V0.015 <0.4 *380 E1.0 <4.6 E1.9 E1.6

USAWC-17 E0.036 <0.4 210 <1.8 <4.8 E1.4 <4.5

USAWC-21 V0.018 <0.5 130 <1.8 <2.5 E1.5 <2.4

USAWC-23 E0.044 <0.4 *360 E1.5 <2.3 2.6 2.4

USAWE-01 0.064 E0.4 240 E6.8 <4.1 E1.3 E2.7

USAWE-02 E0.051 <0.4 200 E1.5 <5.0 <2.3 E1.4

USAWE-03 E0.039 <0.4 * 1,400 E3.2 E2.2 <2.1 4.6

USAWE-04 0.207 E0.4 * 2,200 14.0 E9.4 3.4 6.9

USAWR-03 0.088 V0.2 *580 8.7 4.7 4.5 6.6

USAWR-08 0.107 <0.5 *310 *17.3 12.5 E3.8 10.5

USAWR-11 0.109 <0.5 *580 E4.1 E2.8 E2.9 E3.3

USAWR-12 0.067 <0.5 *520 <6.1 <5.0 E2.3 E1.8

USAWS-02 0.072 <0.5 220 <11.0 <8.5 6.8 8.1

USAWS-06 0.087 0.6 210 E1.6 <2.0 4.4 3.5

USAWS-08 0.278 V0.3 * 1,400 <3.5 <4.1 E3.5 E2.9

USAWS-12 0.260 0.6 *940 E7.7 <6.6 3.8 4.8

USAWS-14 E0.057 V0.2 230 E2.2 <3.3 E2.6 E3.2

USAWS-15 E0.043 <0.5 160 <5.3 <4.5 7.2 7.0

USAWS-18 E0.067 <0.5 170 <6.3 <6.3 8.4 9.8

USAWS-20 V0.019 <0.5 *350 E1.6 <7.9 4.3 E5.7

USAWY-05 V0.021 <0.5 200 <2.1 <2.0 E2.3 3.1

USAWY-06 E0.037 <0.5 210 E0.9 <2.6 E2.1 E2.1

* Value exceeds threshold level (lower threshold level for radon is lower).

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 MCL-US threshold for radium is the sum of radium-226 and radium-228.

3

 Two MCLs have been proposed for Radon-222. The proposed alternative MCL is in parentheses.

Table 16. Radioactive constituents in ground-water samples collected for the Upper Santa Ana Watershed Ground-Water Ambient 

Monitoring and Assessment (GAMA) Program, California, November 2006–February 2007.

[GAMA well identification No: USAW, Upper Santa Ana Watershed study unit. Study area grid wells: USAWB, Bunker Hill/Cajon/Rialto-Colton; USAWC, 

Cucamonga/Chino; USAWE, Elsinore; USAWR, Riverside-Arlington/Temescal; USAWS, San Jacinto; USAWY, Yucaipa/San Timoteo. The five-digit number 

in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent or property. The data 

reported in this table has been screened using the reporting algorithm described in the Appendix under “Data Reporting”. The screened data are not stored 

in NWIS; raw data for these constituents are stored in NWIS under the parameter codes listed in the table. Samples from the 32 slow wells were analyzed. 

Abbreviations: MCL-CA, California Department of Public Health maximum contaminant level; MCL-US, U.S. Environmental Protection Agency maximum 

contaminant level; E, estimated value; V, analyte detected in sample and an associated blank thus data are not included in ground-water quality assessment; 

pCi/L, picocuries per liter; <, less than sample-specific critical level]
88 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

GAMA well 

identification

number

Total coliform 

(colonies/100 mL) (90900)

Threshold type1 MCL-US

Threshold value 5 percent of samples per month

USAWR-03 45

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 17. Microbial indicators detected in samples collected 

for the Upper Santa Ana Watershed Groundwater Ambient 

Monitoring and Assessment (GAMA) study, California, 

November 2006 to March 2007.

[The five-digit number in parentheses below the constituent name is 

the U.S. Geological Survey parameter code used to uniquely identify a 

specific constituent or property. Samples from the 32 slow wells were 

analyzed, but only the one sample with a detection is listed. Abbreviations: 

USAWR, Upper Santa Ana Watershed study unit grid well; MCL-US, 

U.S. Environmental Protection Agency maximum contaminant level; mL, 

milliliter]
Appendix 89

Appendix 

This appendix includes discussions of the methods 

used to collect and analyze ground-water samples and report 

the data for USAW. These methods were selected to obtain 

representative samples of the ground water from each well 

and to minimize 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 are also 

discussed.

Sample Collection and Analysis

Sample Collection

Ground-water samples were collected using standard 

and modified USGS protocols (Koterba and others, 1995; 

U.S. Geological Survey, variously dated), and protocols 

described by Weiss (1968), Shelton and others (2001), Ball 

and McClesky (2003a,b), and Wright and others (2005). 

Before sampling, each well was pumped continuously in order 

to purge at least three casing-volumes of water from the well 

(U.S. Geological Survey, variously dated). Samples were 

collected using Teflon tubing with brass and stainless-steel 

fittings attached to a sampling point on the well discharge 

pipe as close to the well as possible. The sampling point was 

always located upstream of any well-head treatment system 

or water storage tank. If a chlorinating system was attached 

to the well, the chlorinator was shut off before purging 

and sampling the well in order to clear all chlorine out of 

the system. Samples collected using the fast, topical, and 

intermediate schedules were collected at the well head through 

a foot-long length of Teflon tubing (Wright and others, 2005). 

These samples were collected inside an enclosed chamber 

when environmental conditions dictated (for example, windy 

conditions or obvious sources of contamination observed 

nearby). Samples collected using the slow schedule were 

collected inside an enclosed chamber located inside a mobile 

laboratory and connected to the well head by a 10 to 50 foot 

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, ground water was pumped 

through a flow-through chamber fitted with a multi-probe 

meter that simultaneously measured dissolved oxygen, 

temperature, pH, turbidity, and specific conductance. Field 

measurements were made in accordance with protocols in 

the USGS National Field Manual (Wilde and Radtke, 2005; 

Wilde, 2006; Lewis, 2006; Radtke and others, 2005; Wilde 

and others, 2006). All sensors on the multi-probe meter 

were calibrated daily. Measured temperature, dissolved 

oxygen, pH, and specific conductance values were recorded 

at 5-minute intervals for at least 30 minutes, and after these 

values remained stable for 20 minutes, samples to be analyzed 

in the laboratory were collected. Field measurements and 

instrument calibrations were recorded by hand on field 

record sheets and electronically in PCFF-GAMA, a software 

package designed by the USGS with support from the 

GAMA program. Analytical service requests and chain of 

custody documentation also were managed by PCFF-GAMA. 

Information from PCFF-GAMA was uploaded directly into 

NWIS at the end of each week that samples were collected. 

For analyses requiring filtered water, ground water was 

diverted through a 0.45-μm pore size vented capsule filter, 

a disk filter, or a 0.7-μm pore size baked glass-fiber filter 

depending on the protocol for the analysis (U.S. Geological 

Survey, variously dated; Wilde and others, 2004). Before 

samples were collected, polyethylene sample bottles were 

pre-rinsed using native water three times. 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 USGS National Water 

Quality Laboratory (NWQL).

Temperature-sensitive samples were stored on ice before 

being shipped daily to the various laboratories. The nontemperature sensitive samples to be analyzed for tritium, 

noble gases, chromium speciation and stable isotopes were 

shipped monthly, while samples to be analyzed for volatile 

organic compounds, pesticides, pharmaceuticals, potential 

wastewater indicator constituents, compounds of special 

interest, dissolved organic carbon, nutrients, major, minor, 

and trace elements, standard dissolved gases, radium isotopes, 

gross alpha and beta radioactivity, and radon-222 were 

shipped daily. Samples to be analyzed for dissolved gases 

were shipped at the end of each sampling week. Samples for 

nitrogen and oxygen isotopes of nitrate were frozen at the end 

of each sampling week and shipped monthly.

Detailed sampling protocols for individual analyses and 

groups of analytes are described by Koterba and others (1995) 

and in the USGS National Field Manual (U.S. Geological 

Survey, variously dated; Wilde and others, 2004) and 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. 

Six normal (6 N) hydrochloric acid (HCl) was added as a 

preservative to all the VOC samples except the additional 

1,2,3-TCP samples collected to obtain a lower detection limit 

for this VOC. Perchlorate samples were collected in 125-mL 

polyethylene bottles. Tritium samples were collected by 

bottom filling two 1-L polyethylene bottles with unfiltered 

ground water, after first overfilling the bottle with three 

volumes of water. Stable isotopes of hydrogen and oxygen in 

water were collected in 60-mL clear glass bottles filled with 

unfiltered water, sealed with a conical cap, and secured by 

electrical tape to prevent leakage and evaporation.
90 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Samples to be analyzed for pesticides and pesticide 

degradation products, potential wastewater-indicator 

constituents, pharmaceutical compounds, 1,4-dioxane, and 

N-nitrosodimethylamine (NDMA) samples were collected in 

1-L baked amber glass bottles. Pesticide and pharmaceutical 

samples were filtered with a 0.7-μm pore-size glass-fiber filter, 

whereas the NDMA samples were filtered at the Montgomery 

Watson-Harza laboratory before analysis. Potential 

wastewater-indicator samples were unfiltered.

Ground-water samples to be analyzed for major and 

minor ions, trace elements, alkalinity (laboratory), and total 

dissolved solids analyses were processed by filling one 

250-mL polyethylene bottle with raw groundwater, and one 

500-mL and one 250-mL polyethylene bottles with filtered 

ground water (Wilde and others, 2004). The filter used was 

a 0.45-μm pore-size disposable Whatman capsule filter. The 

250-mL filtered sample was then preserved with 7.5 N nitric 

acid. Mercury samples were collected by filtering ground 

water into 250-mL glass bottles and preserving them with 

6 N hydrochloric acid. Arsenic and iron speciation samples 

were filtered into 250-mL polyethylene bottles that were 

covered with tape to prevent light exposure, and preserved 

with 6 N Hydrochloric acid. The nutrient sample was filtered 

into a 125-mL brown polyethylene bottle. The sample for 

isotopes of nitrogen and oxygen in nitrate was filtered into a 

second 125-mL brown polyethylene bottle. Radium isotopes, 

and gross alpha and beta radiation samples were filtered 

into 1-L polyethylene bottles and acidified with 7.5 N nitric 

acid. Carbon isotope samples were filtered and bottom-filled 

into two 500-mL glass bottles that were first overfilled with 

three bottle volumes of ground water. These samples had 

no headspace and were sealed with a conical cap to avoid 

atmospheric contamination. The sample to be analyzed for 

field alkalinity titration was collected by filtering ground water 

into a 500-mL polyethylene bottle.

Samples to be analyzed for DOC, oxidation-reduction 

species of chromium, radon-222, dissolved standard and noble 

gases, and microbial constituents were collected from the 

hose bib at the well head, regardless of the sampling schedule 

(fast, intermediate or slow). DOC was collected after rinsing 

the sampling equipment with organic blank water (Wilde 

and others, 2004). Using a 50-mL syringe and a 0.45-μm 

disk filter, the ground water sample then was filtered into a 

125-mL baked glass bottle and preserved with 4.5 N sulfuric 

acid. The chromium speciation sample was collected using a 

10-mL syringe with an attached 0.45-μm disk filter. After the 

syringe was thoroughly rinsed and filled with ground water, 

4 mL were forced through the disk filter; the next 2 mL of the 

ground water was slowly filtered into a small centrifuge vial 

for analysis of total chromium. Hexavalent chromium, Cr(VI), 

was then collected by attaching a small cation exchange 

column to the syringe filter, and after conditioning the column 

with a 2-mL of sample water, 2 mL were collected in a second 

centrifuge vial. Both vials were preserved with 10 μL of 7.5 N 

nitric acid (Ball and McClesky, 2003a,b).

To collect samples to be analyzed for radon-222, a 

stainless-steel and Teflon valve assembly was attached to 

the sampling port at the well head (Wilde and others, 2004). 

The valve was partially closed to create back pressure, and a 

10-mL sample was collected through a Teflon septum on the 

value assembly using a glass syringe affixed with a stainlesssteel needle. The sample was then injected into a 25-mL vial 

partially filled with scintillation mixture (mineral oil) and 

shaken. The vial was then placed in a cardboard tube in order 

to shield it from light during shipping. 

Samples collected for the determination of standard 

dissolved gases (and subsequent determination of nitrogen gas 

isotopes) were collected by bottom-filling a 150-mL sample 

bottle immersed in a water-filled beaker. Air was excluded 

from the sample by sealing the bottle under water with a 

rubber stopper pierced with a perforated needle. As the stopper 

was inserted residual air was voided through the perforated 

needle. Noble gases were collected in 3/8-in copper tubes 

using reinforced nylon tubing connected to the hose bib at 

the wellhead. Ground water 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 were 

then tightened, trapping a sample of ground water for analyses 

of noble gases (Weiss, 1968). 

Samples to be analyzed for microbial constituents also 

were collected at the well head following protocols described 

by Myers (2004) and Bushon (2003). Before samples were 

collected, the sampling port was sterilized using isopropyl 

alcohol, and ground water was run through the sampling 

port for at least 3 minutes to remove any traces of the 

sterilizing agent. Two sterilized 250-mL bottles were then 

filled with ground water to be analyzed for coliform (total and 

Escherichia coliform determinations), and one sterilized 3-liter 

carboy was filled to be analyzed for coliphage (F specific and 

somatic coliphage determinations).

Sample Analysis

Ten laboratories performed chemical and microbial 

analyses for this study (see 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 (Maloney, 2005; Pirkey and 

Glodt, 1998). Laboratory quality control samples—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 continuously 

tested and laboratory reporting levels updated accordingly. 

NWQL maintains National Environmental Laboratory 

Accreditation Program (NELAP) and other certifications 

(http://nwql.usgs.gov/Public/lab_cert.shtml). In addition, 

the Branch of Quality Systems within the USGS Office of 

Water Quality independently oversees quality assurance at the 

NWQL and laboratories contracted by the NWQL. The Branch 
Appendix 91

of Quality Systems also runs a national field quality assurance 

program that includes testing all USGS field personal annually 

for proficiency in making field water-quality measurements 

(http://bqs.usgs.gov/nfqa/). Results for analyses made at 

the NWQL or by laboratories contracted by the NWQL are 

uploaded directly into NWIS by the NWQL.

Turbidity, field alkalinity, total coliforms, and Escherichia 

coliform (E. coli) were measured in the mobile laboratory 

at the well site. Turbidity was measured in the field with a 

calibrated turbidity meter. Total coliforms and Escherichia 

coliform (E. coli) plates were prepared using sterilized 

equipment and reagents (Myers, 2004). Plates were counted 

under an ultraviolet light, following a 22–24 hour incubation 

time. Alkalinity and the concentrations of bicarbonate (HCO3

-

) 

and carbonate (CO3

2-) in filtered samples were measured by 

Gran’s titration method (Gran, 1952; Rounds, 2006; Stumm 

and Morgan, 1996). 

Concentrations of HCO3

-

 and CO3

2- were also calculated 

using the laboratory alkalinity and pH measurements. 

Calculations were made using the advanced speciation method 

(http://or.water.usgs.gov/alk/methods.html) with ρK1 = 6.35, 

ρK2 = 10.33, and ρKW = 14.

Data Reporting

The following section details the reporting conventions 

of the USGS National Water Quality Laboratory (NWQL) 

and how these reporting conventions were established. It 

also describes details of the procedure that GAMA uses to 

screen radiochemical data. Finally, reporting conventions 

for constituents that are determined by multiple analytical 

methods are described.

Laboratory Reporting Conventions

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 is actually in a sample at a 

concentration greater than or equal to the LRL) to less than 

1 percent (Childress, and others, 1999). The LRL is usually 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 MDL determinations made over an extended period of 

time. LT-MDLs are continually monitored and updated. The 

method detection limit (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 MDL there is less than 1 percent chance of a false 

positive) (U.S. Environmental Protection Agency, 2002a). The 

USGS NWQL updates LRL values regularly and the values 

listed in this report were in effect during the period groundwater samples from the USAW study unit were analyzed 

(November 2006 to March 2007).

Some compound concentrations in this study are reported 

using minimum reporting levels or method uncertainties. 

The minimum reporting level 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 in which the 

true value will be found. 

Concentrations between the LRL and the LT-MDL are 

reported as estimated concentrations (designated with an “E” 

before the values in the tables and text). For informationrich methods, concentrations below the LRL have a high 

certainty of detection, but the precise concentration is 

uncertain. Information-rich methods are those that use gas 

chromatography or high-performance liquid chromatography 

(HPLC) with mass spectrometry detection (to analyze for 

VOCs, gasoline oxygenates and degradates, pesticides, 

pharmaceuticals, potential wastewater-indicators). Compounds 

are identified by the presence of characteristic fragmentation 

patterns in their mass spectra in addition to being 

quantified by measurement of peak areas at their associated 

chromatographic retention times. E-values also may result 

from detections outside the range of calibration standards, 

for detections that did not meet all laboratory quality-control 

criteria, and for samples that were diluted before being 

analyzed (Childress and others, 1999).

Detections that may have resulted from inadvertent 

sample contamination are reported with a “V” before the 

values in the tables. The potential for sample contamination 

was assessed using results from field, source-solution, and 

laboratory blanks.

The reporting levels for radiochemical constituents 

(gross-alpha radioactivity, gross-beta radioactivity, 

radium-226, and radium-228) in picocuries per liter (pCi/L) 

were based on a sample-specific minimum detectable 

concentration (SSMDC), a sample-specific critical value, and 

the combined standard uncertainty (CSU) (U.S. Environmental 

Protection Agency, 2004; Bennett and others, 2006). A result 

above the critical value represents a greater-than-95-percent 

certainty that the result is greater than zero (significantly 

different from the instrument’s background response to a 

blank sample), and a result above the SSMDC represents a 

greater-than-95-percent certainty that the result is greater than 

the critical value. Using these reporting level elements, three 

unique cases were possible when screening the raw analytical 

data. If the analytical result was less than the critical value 

(case 1), the analyte was considered not detected, and the 

concentration was reported as less than the SSMDC. If the 

analytical result was greater than the critical value, the ratio 

of the CSU to the analytical result was calculated as a percent 

(percent relative CSU). For those samples with percent relative 

CSU greater than 20 percent (case 2), concentrations were 

reported as estimated values (designated by an “E” preceding 

the value). For those samples with percent relative CSU less 

than 20 percent (case 3), concentrations were reported with no 

qualifiers.
92 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Stable isotopic compositions of oxygen, hydrogen, and 

carbon are reported as relative isotope ratios in units of per mil 

using the standard delta notation (Coplen and others, 2002):

i sample

reference

18

13 2

sample

E 1 1,000 per mil,

where

is the heavier isotope of the element ( O for

oxygen, C for carbon, or H for hydrogen),

is the ratio of the abundance of the heavier

 isotope o

i

R

R

E

R

  δ = − •    

18 13 2

16 12 1

reference

f the element ( O, C, or H) 

to the lighter isotope of the element 

( O, C, or H) in the sample and,

is the ratio of the abundance of the heavier

isotope of the element to the lighter isot

R

ope 

of the element in the reference material 

hydrogen.

(1)

The reference material for oxygen and hydrogen is 

Vienna Standard Mean Ocean Water (VSMOW), which is 

assigned δ18O and δ2H values of 0 per mil. The reference 

material for carbon is Vienna Peedee Belemnite (VPDB), 

which is assigned a δ13C value of 0 per mil. Positive values 

indicate enrichment of the heavier isotope and negative values 

indicate depletion of the heavier isotope, compared to the 

ratios in the reference material.

Constituents on Multiple Analytical Schedules

Results for 18 constituents targeted in the USAW study 

were determined by more than one analytical schedule or more 

than one laboratory (table A2). All results, including these 

multiple or “duplicate” analyses are included in this report. 

The data tables that include the 18 constituents with duplicate 

results identify the preferred methods and provide direction 

for locating duplicate results for the constituents in other 

tables. Preferred methods were selected based on procedures 

recommended by the NWQL. Methods having full approval 

are preferred over those having provisional approval, and 

approved methods are favored over research methods. The 

most precise method (the one that has lower LRLs for the 

overlapping constituents) is preferred, and certain analytical 

technologies are preferred over others (for example gas 

chromatography over liquid chromatography). 

Duplicate results were usually in substantial agreement 

for these constituents. In particular, comparisons between field 

and laboratory determinations of pH, specific conductance, 

and alkalinity indicated that field calibration and measurement 

techniques were reliable and that laboratory results agreed 

with (were similar to) the corresponding sample sent from 

the field. Dissolved argon results measured by the Reston 

Chlorofluorocarbon Laboratory (table 14) are in good 

agreement with results from Lawrence Livermore National 

Laboratory (table 15) when the Lawrence Livermore results 

are converted to mg/L.

The duplicate results for two compounds in particular 

merit note: caffeine and tebuthiuron. Caffeine, detected 

four times by the pharmaceutical schedule 2080, was not 

detected in any sample by the preferred method of analysis, 

schedule 2060. Two of the four concentrations detected were 

greater than the schedule 2060 LRL, and two detections were 

accompanied by detections of 1,7-dimethylxanthine, a caffeine 

degradate. Tebuthiuron was detected more frequently and at 

lower concentrations by the non-preferred method schedule 

2060 than by the preferred method of analysis schedule 

2033. However, all of the schedule 2060 detections of 

tebuthiuron were at concentrations less than the LT-MDL for 

this compound and were therefore not included in detection 

frequency calculations.

Scenario

Critical 

value 

(pCi/L)

SSMDC 

(pCi/L)

Combined 

standard 

uncertainty 

(pCi/L)

Relative 

CSU

(percent)

Result 

(pCi/L)

Raw Reported

Case 1 - Result less than 

critical value

1.4 3.2 ±1.2 133 0.9 <3.2

Case 2 – Relative combined 

standard uncertainty 

greater than 20 percent

0.5 1.4 ±0.6 32 2.0 E2.0

Case 3 – Relative combined 

standard uncertainty less 

than 20 percent

0.4 1.1 ±0.5 14 3.2 3.2
Appendix 93

Quality-Assurance Methods

The quality-assurance methods used for this study follow 

protocols described in the USGS National Field Manual 

(U.S. Geological Survey, variously dated), protocols used 

by the USGS NAWQA program (Koterba and others, 1995), 

and the NWQL quality-assurance plan (Maloney, 2005). 

Quality-control (QC) samples were collected concurrently 

with approximately 21 percent of the samples in the USAW 

study to assess the bias and variability of water-quality data 

potentially possibly introduced during sample collection, 

processing, storage, transportation, and laboratory analysis, as 

well as intrinsic variability within the ground water itself. Four 

types of QC samples were collected and analyzed: blanks, 

field replicates, laboratory surrogates, and laboratory matrix 

spikes.

Blanks

Blank samples (blanks) were collected using water 

(Nitrogen-Purged Universal blank water) certified by the 

NWQL to contain less than the LRL or MRL of the analytes 

investigated in the study. Two types of blanks were collected: 

source-solution and field blanks. Source-solution blanks 

were collected to verify that the blank water used for the field 

blanks was free of analytes. Field and source solution blanks 

were collected at 8 percent of the wells sampled to determine 

if equipment or procedures used in the field or laboratory 

had introduced contamination. Field blanks were analyzed 

for VOCs, pesticides, potential wastewater indicators, 

pharmaceuticals, constituents of special interest, nutrients, 

dissolved organic carbon, major and minor ions, trace 

elements, radioactive constituents. Suitable blank water is 

not available for tritium, coliphage, or noble gases; thus field 

blanks were not collected for these constituents. Filter and 

procedure blanks were performed with each sample plating 

of samples for E. coli and total coliforms: none were detected 

during this study. 

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 ground-water samples. Blank water 

used for field blanks was either pumped or poured through 

the sampling equipment (fittings and tubing) used to collect 

ground water, then processed and transported using the same 

protocols as those used for the ground-water samples. 

If a constituent was detected in a field blank, the 

associated source-solution blank results were examined 

for similar constituent detections. If the field blank and 

the source-solution blank contained the constituent, the 

source solution water was interpreted as the origin of the 

contamination in the blanks, and the field blank detections 

using the same blank water were disregarded. Source-solution 

blanks were only performed for VOCs, pharmaceuticals, 

perchlorate, NDMA, 1,4-Dioxane, and 1,2,3-TCP. If a 

field blank detection could not be attributed to the source 

solution, the ground-water samples collected before and 

after the blank were evaluated. If the ground-water samples 

collected before or after the contaminated field blank were not 

contaminated, then carry-over contamination was ruled out. If 

the concentration of an analyte detected in a field blank plus 

one-half the LRL for that analyte (one-half the sample-specific 

method detection concentration in the case of radium) was 

greater than the concentration measured in a ground-water 

sample collected immediately before or after the blank sample, 

the ground-water value was V-coded (table A3). These results 

have a ‘V’ preceding the value in results tables (4–17), and 

are excluded from the summary statistics. If a compound was 

detected in multiple field blanks and the detections could not 

be attributed to the source-solution water, any ground-water 

sample in which the compound in question was detected was 

evaluated for possible contamination.

Replicates 

Sequential replicate samples were collected to assess 

variability that may result from processing and analyzing 

inorganic and organic constituents. Relative standard deviation 

(RSD) of the measured values was used in determining 

the variability between replicate pairs for each compound 

(tables A4A–B). The RSD is defined as 100 times the standard 

deviation divided by the mean concentration for each replicate 

pair of samples. If a constituent was not detected in one 

replicate and its concentration was estimated to be below 

the LRL or MRL in the other replicate, the RSD was set 

to zero because the values are analytically identical. If one 

value for a sample pair was reported as a non-detection and 

the other value was greater than the LRL or MRL, the nondetection value was set equal to one-quarter of the LRL and 

the RSD was calculated (Hamlin and others, 2002). Values 

of RSD less than 20 percent are considered acceptable in 

this study. High RSD values for a compound may indicate 

analytical uncertainty at low concentrations, particularly for 

concentrations within an order of magnitude of LT-MDL or 

MDL. Sequential replicate samples were collected at 8 percent 

of the wells sampled.
94 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Matrix Spikes

Adding 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 

ground water, on the analytical technique used to measure the 

constituent. The known compounds added to matrix spikes 

are the same as those being analyzed using the method. 

This enables matrix interferences to be analyzed with each 

compound. Matrix spikes were added at the laboratory that 

analyzed the samples. Compounds with low recoveries are 

of concern if environmental concentrations are close to the 

MCLs; a concentration below an MCL could falsely indicate 

that the standard was not exceeded. Conversely, compounds 

with high recoveries are of concern if the environmental 

concentrations exceed MCLs: a high recovery could falsely 

indicate a concentration above the MCL. 

Acceptable ranges for matrix-spike recoveries are based 

on the acceptable ranges established for laboratory “set” spike 

recoveries. Laboratory set spikes are aliquots of laboratory 

blank water to which the same spike solution as that used for 

the matrix spikes has been added. One set spike is analyzed 

with each set of samples. Acceptable ranges for set spike 

recoveries are 70 to 130 percent for NWQL schedules 2020 

and 4433 (Connor and others, 1998; Zaugg and others, 2002), 

60 to 120 percent for NWQL schedules 2033 and 2060 

(Sandstrom and others, 2001; Furlong and others, 2001), 

and 60 to 130 percent for schedule 2080 (Kolpin and others, 

2002). We used these ranges to define 70 to 130 percent as 

the acceptable range for matrix-spike recoveries for organic 

compounds in this study. 

Matrix spikes were added to samples to be analyzed for 

VOCs, pesticide compounds, pharmaceutical compounds, 

potential wastewater-indicator constituents, NDMA, 

1,4-Dioxane, 1,2,3-TCP, radium isotopes, and gross alpha 

and beta radiation because the analytical methods used for 

these constituents may be susceptible to matrix interferences. 

Replicate samples to which matrix spikes were to be added 

were collected at 7 percent of the wells sampled, although not 

all analyte classes listed above were added to samples from 

every well (tables A5A-G).

Surrogates

Surrogate compounds are added to environmental 

samples in the laboratory before analysis in order to evaluate 

the recovery of similar constituents. Surrogate compounds 

were added to all ground-water and quality-control samples 

that were analyzed for VOCs, pesticide compounds, 

pharmaceutical compounds, potential wastewater-indicator 

compounds, NDMA,1,4,-Dioxane, and 1,2,3-TCP (table A6). 

Most of the surrogate compounds are deuterated analogs 

of compounds being analyzed. For example, the surrogate 

toluene-d8 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 

during the analytical procedure, but the small mass difference 

between the two causes slightly different chromatographic 

retention times; thus using 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 found in environmental 

samples. Surrogates are used to identify general problems 

that may arise during sample analysis that could affect the 

analysis results for all compounds in that sample. Potential 

problems include matrix interferences (such as high levels 

of dissolved organic carbon) that produce a positive bias, 

and incomplete laboratory recovery (possibly caused by 

improperly maintaining and calibrating analytical equipment) 

that produces a negative bias. A 70 to 130 percent recovery 

of surrogates is generally considered acceptable; values 

outside this range indicate possible problems with processing 

and analyzing samples (table A6) (Connor and others, 1998; 

Sandstrom and others, 2001).

Quality-Control Results

Detections of Constituents in Field Blanks

Field blanks were collected at eight wells sampled in 

USAW. Three of the field blanks were collected at wells 

sampled using the “slow” analytical schedule and using 

equipment dedicated to this type of sampling. The other 

five field blanks were collected at “fast”, “intermediate”, or 

“topical” wells using a different equipment set-up. Table A3

presents a summary of detections in field blanks. The table 

summarizes results separately for blanks collected using 

the “slow” analytical schedule and those collected using the 

“fast”, “intermediate”, or “topical” schedule. 

All eight field blanks were analyzed for VOCs, and five 

VOCs were detected in the blanks. However, since three of 

these compounds were not detected in ground-water samples, 

their occurrence in field blanks was of no consequence. 

1,2,4-trimethylbenzene was detected in 19 ground-water 

samples and in a single field blank at a concentration similar 

to its concentrations in many of the ground-water samples. 

However, since this compound was not detected in the 

ground-water samples collected using the same equipment 

set-up immediately before and after it was detected in the field 

blank, no ground-water detections of 1,2,4-trimethylbenzene 

were V-coded. Detections of toluene in field blanks collected 

at wells using both types of sampling equipment and at 

concentrations similar to those detected in ground-water 

samples resulted in the censoring of all (5) USAW groundwater detections of toluene. 
Appendix 95

Seven USAW field blanks were analyzed for pesticides. 

The pesticides atrazine and simazine were detected in one 

field blank collected on a “fast” analytical schedule on 

February 8, 2007 (table A3). The estimated concentration 

of atrazine detected in this blank was 0.005 μg/L, and the 

estimated concentration of simazine detected was 0.004 μg/L. 

Neither atrazine nor simazine were detected in the groundwater sample collected after the field blank. Atrazine was not 

detected in the ground-water sample collected immediately 

before the field blank, but simazine was detected at a 

concentration of 0.006 μg/L. However, this simazine detection 

was V-coded because the concentration in the blank plus 

half the simazine LRL is greater than 0.006 μg/L. No other 

pesticide detections were V-coded.

Seven USAW field blanks were analyzed for potential 

wastewater indicator compounds. Eighteen potential 

wastewater indicator compounds were detected in the blank 

collected February 8, 2007. The NWQL subsequently 

determined that this blank was among 60 samples nationwide that were inadvertently cross-contaminated as a result 

of a change in method procedure. An additional wastewater 

indicator in a blank was d-limonene detected at an estimated 

concentration of 0.03 μg/L in a blank collected November 28, 

2006, using a “fast” equipment set-up. These issues formed 

part of the basis for the decision to omit the results for this 

analytical method from this report.

Five USAW field blanks were analyzed for nutrients, 

major and minor ions, and trace elements. The only nutrient 

species that was detected in a field blank was total nitrogen, 

detected in one field blank at a concentration of 0.14 mg/L 

(table A3). However, no ground-water samples were V-coded 

for total dissolved nitrogen because the resulting level 

to require a V-code (0.14 mg/L plus one-half the LRL of 

0.03 mg/L) was far below any of the concentrations detected 

in ground-water samples. Similarly, calcium was the only 

major ion detected in a USAW field blank, present at an 

estimated concentration of 0.013 mg/L in one blank. Since 

the lowest concentration of calcium in any of the groundwater samples was 3 mg/L, no calcium results were V-coded. 

Single blank detections of two trace elements—barium and 

chromium—were also too small to result in censoring groundwater results. Mercury, detected one time in a field blank, was 

not detected in the associated ground-water sample. Therefore, 

the isolated detection did not result in V-coding any groundwater mercury results. 

However, multiple blank detections of three trace 

elements—copper, lead, and zinc—collectively resulted 

in censoring 45 ground-water results. A single detection 

of aluminum in the February 8, 2007, blank collected with 

a “fast” equipment set-up was probably the result of field 

conditions. The field crew noted, as well as documented 

with photographs, an elaborate combination of metal fittings 

necessary to connect the field blank pump to the sampling 

line. Therefore, it would be inappropriate to censor detections 

of aluminum in ground-water samples collected before and 

after this blank. The ground-water sample associated with the 

field blank had an aluminum concentration of 4.4 μg/L, which 

is greater than the censoring level that would result from the 

1.6-μg/L concentration detected in the blank. Note that the 

USGS Branch of Quality Systems determined that aluminum 

and lead had positive analytical biases (of 9 and 14 percent, 

respectively) during the time that USAW samples were 

analyzed at the NWQL.

Field blanks were collected at three of the thirty-two 

sites sampled for iron, arsenic, and chromium speciation 

analysis by the USGS Trace Metal Laboratory (TML). The 

concentration of arsenic in one field blank was 2.5 μg/L, and 

the concentrations of iron in two field blanks were 4 μg/L and 

3 μg/L. Iron and arsenic detected in ground water by TML 

(table A3) were not V-coded because these results were used 

only to determine the relative proportions of the oxidationreduction species of these metals in the samples. The preferred 

methods of analyses for these metals were those used by 

NWQL (table 11).

NDMA was detected in two of the three field blanks for 

which it was analyzed (table A3), and the concentrations in the 

field blanks were greater than those of the two ground-water 

samples in which it was detected. Therefore, both of these 

ground-water detections of NDMA were V-coded.

DOC was detected in two of the three field blanks for 

which it was analyzed at concentrations similar to those 

detected in ground-water samples. While all three field blanks 

analyzed for DOC were collected at slow wells, the collection 

procedure and equipment used to process samples for this 

analyte are the same at all wells. As a result, all but one of 

the 25 DOC detections in USAW ground-water samples were 

V-coded.

Two field blanks were collected to be analyzed for 

radioactive constituents. Radium-226 and radium-228 

were detected in both blanks. The greatest concentration of 

radium-226 detected in a field blank was estimated to be 

0.019 pCi/L. The greatest such concentration of radium-228 

was estimated to be 0.08 pCi/L. Since radium was detected in 

both blanks, censoring levels for these analytes were obtained 

derived by adding the maximum blank concentrations to 

one-half the sample-specific method detection concentration 

determined for the ground-water detections; a censoring 

strategy analogous to that used for analytes with fixed LRLs. 

This resulted in censoring 7 ground-water detections of 

radium-226 and 5 ground-water detections of radium-228.

No compounds were detected in field blanks for the 

following analytes or groups: pharmaceutical compounds (7 

field blanks), perchlorate (8 field blanks), 1,2,3-TCP (3 field 

blanks), and 1,4-dioxane (3 field blanks).
96 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Variability in Replicate Samples

Tables A4A,B summarize the results of replicate 

analyses of constituents detected in ground-water samples 

collected in the USAW study. More than 1,000 replicate 

analyses were evaluated for constituents detected in at least 

one ground-water sample. Concentrations or activities in the 

environmental and replicate samples are given in tables A4A,B

for all replicate analyses with RSD values greater than 

20 percent. Most replicate analyses yielded RSD values less 

than 20 percent. Constituents in replicate samples whose 

analyses yielded RSD values greater than 20 percent include 

the VOC 1,2,4-trimethylbenzene; the potential wastewater 

indicators caffeine, 3,4-Dichlorophenyl isocyanate, phenol, 

and tetrachloroethene (PCE); the trace elements copper, 

nickel and zinc (table A4A); dissolved oxygen measured by 

the Reston Chlorofluorocarbon laboratory; four noble gases; 

and four radioactive constituents (table A4B). One of these, 

3,4-Dichlorophenyl isocyanate, is recognized by the NWQL 

as a highly variable compound in the potential wastewater 

indicator laboratory schedule. With one exception each for 

1,2,4-trimethylbenzene, copper, and zinc replicate analyses, 

the magnitudes of the concentrations of the replicate sample 

pairs with RSD values greater than 20 percent were all within 

a factor of five of the LRLs for the respective analytes. At 

these low concentrations, small deviations in measured values 

result in large RSDs. No data were qualified as a result of 

variability in replicate analyses.

Matrix-Spike Recoveries

Tables A5A–G summarize matrix-spike recoveries for 

the USAW study. Adding 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 

ground water, on the analytical technique used to measure 

the constituent. Seven ground-water samples were spiked 

with VOCs to calculate matrix-spike recoveries (table A5A). 

Seventy-nine of the eighty-five VOC spike compounds 

consistently had recoveries within the acceptable range 

of 70 and 130 percent. Three VOC spike compounds—3-

chloro-1-propene, methyl bromide, and vinyl chloride—had 

at least one matrix spike recovery greater than 130 percent. 

Despite this indication of positive analytical bias, none 

of these three compounds were detected in ground-water 

samples. Three VOC spike compounds—carbon disulfide, 

dichlorodifluoromethane, and trichlorofluoromethane—had 

at least one matrix-spike recovery less than 70 percent, and 

the first two of these compounds were not detected in groundwater samples. [NOTE – low recoveries may indicate that the 

compound might not have been detected in some samples if it 

was present at very low concentrations]. 

In contrast to the generally-acceptable matrix spike 

recoveries observed for the VOCs, about half of the pesticide 

and pesticide degradate spike compounds had at least 

one matrix spike recovery outside the acceptable range 

(tables A5B and A5C). Only six of these were on the high 

side of the range with recoveries greater than 130 percent on 

at least one occasion, and only two of those six (bromacil by 

lab schedule 2060 analysis and tebuthiuron by lab schedule 

2033 analysis) were detected in USAW ground-water 

samples. Low spike recoveries for many pesticide compounds 

potentially represent a more serious problem than do high 

spike recoveries. Most (121) of the 134 pesticide compounds 

targeted for analysis in this study for were not detected in 

USAW ground-water samples at or above concentrations equal 

to or greater than their respective long-term method detection 

limits (LT-MDLs). Sixty-six of the 121 compounds that were 

not detected in any ground-water sample had at least one 

matrix spike recovery less than 70 percent, and forty-one of 

these compounds had median matrix spike recoveries of less 

than 70 percent. [NOTE – low recoveries may indicate that the 

compound might not have been detected in some samples if it 

was present at very low concentrations].

There also tended to be low matrix spike recoveries for 

the six samples spiked with potential wastewater indicator 

compounds (table A5D). All but one (Bisphenol A) of these 

compounds had at least one matrix spike recovery less than 

70 percent, and most of these compounds had median matrix 

spike recoveries of less than 70 percent. [NOTE – low 

recoveries may indicate that the compound might not have 

been detected in some samples if it was present at very low 

concentrations].

Six ground-water samples were spiked with 

pharmaceutical compounds. Five of the fourteen 

pharmaceutical compounds recovered within the acceptable 

range of 70 to 130 percent in all six tests, but nine compounds 

recovered less than 70 percent for at least one of the six tests 

(table A5E). Two compounds, diltiazem and sulfamethoxazole, 

had low recoveries for all six spiked samples and were not 

detected in any USAW ground-water samples. [NOTE – low 

recoveries may indicate that the compound might not have 

been detected in some samples if it was present at very low 

concentrations].

Two ground-water samples were spiked with NDMA and 

1,2,3-TCP. Spike recoveries for these two compounds were 

within the acceptable range of 70 to 130 percent (table A5F). 

However, the single ground-water sample that was spiked 

with1,4-dioxane had a recovery slightly below the acceptable 

range (69 percent). [NOTE – low recoveries may indicate that 

the compound might not have been detected in some samples 

if it was present at very low concentrations].
Appendix 97

One ground-water sample was spiked with radium-226 

and 228. Two ground-water samples were spiked with gross 

alpha and gross beta radioactivity. Spike recoveries for these 

radioactive constituents were within the acceptable range of 70 

to 130 percent (table A5G). No data were qualified as a result 

of the observed matrix spike recoveries.

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 in columns 

the surrogate, analytical schedule for which it was applied, 

the number of analyses for both blank and ground-water 

samples, the number of surrogate recoveries below 70 percent, 

and the number of surrogate recoveries above 130 percent 

for the blank and non-blank samples. Blank and non-blank 

samples were considered separately to assess whether the 

matrices in non-blank samples affect surrogate recoveries. No 

systematic differences between surrogate recoveries in blank 

and ground-water samples were observed. While 79 percent of 

the surrogate recoveries for VOCs, 86 percent of the surrogate 

recoveries for pesticides, and 98 percent of the surrogate 

recoveries for pharmaceuticals were in the acceptable range of 

70 to 130 percent, only a little more than half of the surrogate 

recoveries for potential wastewater-indicator constituent 

analyses were in the acceptable range. Poor surrogate 

recoveries for the potential wastewater-indicators should not 

be surprising, given the generally low recoveries of matrix 

spikes for this analyte group. About three-fourths of the 

surrogate recoveries for the constituents of special interest—

1,4-dioxane, NDMA, and 1,2,3-trichloropropane—were in 

the acceptable range. No data were qualified as a result of the 

observed surrogate recoveries.

Internal Laboratory Quality-Control Samples for 

Pharmaceutical Compounds

The protocols for analyzing pharmaceutical compounds 

(NWQL schedule 2080) have been used for routine sample 

analysis since October 2005, but because of the newness of 

the method compared with the other methods of analysis used 

in this study, an extra level of quality-control assessment was 

applied to the pharmaceutical data. More rigorous censoring 

was applied to this group of constituents so that only detected 

concentrations greater than one-half the LRL are reported in 

table 7. Also, in addition to the results for field blanks, matrix 

spike recoveries, surrogate recoveries, and replicate variability, 

results for internal laboratory quality control samples that were 

analyzed with USAW ground-water samples were compiled 

and examined. Samples were analyzed in the order received 

by the NWQL in sets that included approximately ten samples. 

The 92 ground-water samples, 6 matrix spikes, 7 replicates, 

5 source solution blanks, and 7 field blanks were analyzed in 

20 different laboratory sets. Each set also included a set blank 

and a set spike. Purified water (de-ionized, carbon-filtered, and 

disinfected by ultraviolet radiation) was used for the set blanks 

and the matrix water for the set spikes (Kolpin and others, 

2002). 

At least one pharmaceutical compound was detected in 

half of the twenty set blanks. Nine of the 14 pharmaceutical 

compounds were detected in set blanks, and the most 

frequently detected compound in these set blanks was cotinine, 

which was detected in 8 set blanks (table A7A). However, 

cotinine was not detected in USAW ground-water samples. 

The rest of the discussion on set blank results will be limited 

to pharmaceutical compounds that were detected in at least 

one USAW ground-water sample at a concentration greater 

than its censoring level following GAMA censoring protocols 

specific to this group of analytes. One of the four such 

pharmaceuticals, 1,7-dimethylxanthine (a caffeine metabolite), 

was not detected in the set blanks. Acetaminophen, caffeine, 

and carbamazepine were detected in 2, 4, and 1 of the 20 set 

blanks, respectively. However, in each case, the concentration 

in the set blank was less than one-tenth the concentration 

detected in the associated ground-water sample; thus no 

pharmaceutical data were V-coded as a result of detections in 

set blanks. 

Recoveries of spike constituents in the set spike samples 

were similar to those in the ground-water matrix spike 

samples. Seven of the 14 pharmaceutical compounds in the 

20 set spikes recovered within the acceptable range of 70 to 

130 percent. Of the remaining 7 compounds, 3 had median 

recoveries within the acceptable range. Median recoveries for 

diltiazem, diphenhydramine, sulfamethoxazole, and warfarin 

were below the acceptable range. [NOTE – low recoveries 

may indicate that the compound might not have been detected 

in some samples if it was present at very low concentrations].
98 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Table A1. Methods used to measure organic, inorganic, and microbial constituents analyzed by the U.S. Geological Survey (USGS) 

National Water Quality Laboratory (NWQL) and contract laboratories.

[Abbreviations: MI agar, supplemented nutrient agar in which coliforms (total and Escherichia) produce distinctly different fluorescence under ultraviolet 

lighting; 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

Alkalinity, field Gran titration with advanced speciation USGS field measurement Gran, 1952; Stumm and Morgan, 

1996; Rounds, 2006

Organic constituents

VOCs Purge and trap capillary gas chromatography/mass spectrometryNWQL, schedule 2020 Connor and others, 1998

Pesticides and degradates Solid-phase extraction and gas chromatography/mass spectrometryNWQL, schedule 2033 Zaugg and others, 1995; Lindley 

and others, 1996; Madsen and 

others, 2003; Sandstrom and 

others, 2001

Polar pesticides and 

degradates

High-performance liquid chromatography/

mass spectrometry

NWQL, schedule 2060 Furlong and others, 2001

Pharmaceuticals Solid-phase extraction and HPLC/mass 

spectrometry

NWQL, schedule 2080 Kolpin and others, 2002

Wastewater-indicators Solid-phase extraction and gas chromatography/mass spectrometryNWQL, schedule 4433 Zaugg and others, 2002

Dissolved organic carbon UV-promoted persulfate oxidation and 

infrared spectrometry

NWQL, lab code 2612 Brenton and Arnett, 1993

Constituents of special interest

Perchlorate Chromatography and mass spectrometry Montgomery Watson-Harza 

Laboratory

Hautman and others, 1999

N-Nitrosodimethylamine 

(NDMA)

Chromatography and mass spectrometry Montgomery Watson-Harza 

Laboratory

U.S. Environmental Protection 

Agency, 1996; U.S. 

Environmental Protection 

Agency, 1999b

1,4-Dioxane Gas chromatography/mass spectrometry Montgomery Watson-Harza 

Laboratory

U.S. Environmental Protection 

Agency, 1996

1,2,3-Trichloropropane Gas chromatography/electron capture 

detector

Montgomery Watson-Harza 

Laboratory

U.S. Environmental Protection 

Agency, 1995

Inorganic constituents

Nutrients Alkaline persulfate digestion, Kjedahl 

digestion

NWQL, schedule 2755 Fishman, 1993; Patton and 

Kryskalla, 2003

Major and minor ions, 

trace elements and 

nutrients

Atomic absorption spectrometry, colorimetry, ion-exchange chromatography, 

inductively-coupled plasma atomic 

emission spectrometry and mass 

spectrometry

NWQL, schedule 1948 Fishman and Friedman, 1989; 

Fishman, 1993; Faires, 1993; 

McLain, 1993; Garbarino, 1999; 

Garbarino and Damrau, 2001; 

American Public Health 

Association, 1998; Garbarino 

and others, 2006

Alkalinity, laboratory Fixed endpoint titration NWQL Schedule 1948 Fishman and Friedman, 1989

Chromium, arsenic and 

iron speciation

Various techniques of ultraviolet visible 

(UV-VIS) spectrophotometry 

and atomic absorbance spectroscopy

USGS Trace Metal 

Laboratory, Boulder, 

Colorado

Stookey, 1970; To and others, 1998; 

Ball and McCleskey, 2003a and 

2003b; McCleskey and others, 

2003
Analyte Analytical 

method

Laboratory and 

analytical schedule Citation(s)

Stable isotopes

Stable isotopes of hydrogen 

and oxygen in water

Gaseous hydrogen and carbon dioxidewater equilibration and stable-isotope 

mass spectrometry

USGS Stable Isotope 

Laboratory, Reston, 

Virginia

Epstein and Mayeda, 1953; Coplen 

and others, 1991; Coplen, 1994

Stable isotopes of nitrogen 

and oxygen in nitrate

Bacterial conversion of nitrate to nitrous 

oxide and mass spectrometry

USGS Stable Isotope 

Laboratory, Reston, 

Virginia, lab code 2900

Sigman and others, 2001; Casciotti 

and others, 2002

Stable isotopes of nitrogen 

in nitrogen gas

Gas chromatography and continuous-flow 

isotope-ratio mass spectrometry on lowpressure headspace (same samples as 

major dissolved gases)

USGS Stable Isotope 

Laboratory, Reston, 

Virginia (research lab)

Modified from Revesz and others, 

1999; Tobias and others, 2007

Carbon isotopes in carbonaceous materialAccelerator mass spectrometry University of Waterloo, 

Environmental Isotope Lab; 

University of Arizona 

Accelerator Mass 

Spectrometry Laboratory

Donahue and others, 1990; Jull and 

others, 2004

Radioactivity and gases

Tritium Electrolytic enrichment-liquid scintillation USGS Stable Isotope and 

Tritium Laboratory, 

Menlo Park, California

Thatcher and others, 1977

Tritium and noble gases Helium-3 in-growth and mass spectrometry Lawrence Livermore 

National Laboratory

Moran and others, 2002; Eaton and 

others, 2004

Standard dissolved gases Gas chromatography/thermal conductivity 

detector and flame ionization detector 

Reston Chlorofluorocarbon 

Laboratory

Busenberg and others, 2001

Radon-222 Liquid scintillation counting NWQL, schedule 1369 American Society for Testing and 

Materials, 1998

Radium 226/228 Alpha activity counting Eberline Analytical Services, 

NWQL method 1262

U.S. Environmental Protection 

Agency, 1980 (USEPA methods 

903 and 904)

Gross alpha and beta 

radioactivity

Alpha and beta activity counting Eberline Analytical Services, 

NWQL method 1792

U.S. Environmental Protection 

Agency, 1980 (USEPA method 

900.0)

Microbial constituents

F-specific and somatic 

coliphage

Single-agar layer (SAL) and two-step 

enrichment methods

USGS Ohio Water Microbiology LaboratoryU.S. Environmental Protection 

Agency, 2001

Total and Escherichia

coliform

Membrane filter technique with "MI agar" USGS field measurement U.S. Environmental Protection 

Agency, 2002b

Table A1. Methods used to measure organic, inorganic, and microbial constituents analyzed by the U.S. Geological Survey (USGS) 

National Water Quality Laboratory (NWQL) and contract laboratories.—Continued

[Abbreviations: MI agar, supplemented nutrient agar in which coliforms (total and Escherichia) produce distinctly different fluorescence under ultraviolet 

lighting; UV, ultraviolet; VOCs, volatile organic compounds]

Table A3 99
100 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Table A2. Analytical schedules for constituents appearing on multiple schedules used to analyze samples collected for the Upper 

Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.

[Preferred analytical schedules are the most precise and accurate of the methods used to analyze the compound in question. LLNL, Lawrence Livermore 

National Laboratory; MWH, Montgomery Watson-Harza Laboratory; TML, U.S. Geological Survey Trace Metal Laboratory; CFC, U.S. Geological Survey 

Chlorofluorocarbon Laboratory; VOC, volatile organic compound]

Constituent Primary constituent 

classification

Analytical schedules—preferred 

listed first (parameter code) Result tables

Results are reported for all analytical schedules that detect the constituent

Alkalinity Water-quality indicator Field (29802), 1948 (29801) 4

Argon dissolved gas LLNL (85563), CFC (82043) 115, 14

Arsenic, total Trace element 1948 (01000), TML (01000) 11, 12

Atrazine Pesticide 2033 (39632), 2060 (39632) 6

Bicarbonate Major ion Field (63786), 1948 (na2) 4, 10

Caffeine Pharmaceutical 32060 (50305), 2080 (50305) 46, 7

Carbaryl Pesticide 32033 (82680), 32060 (49310) 46

Carbofuran Pesticide 32033 (82674), 32060 (49309) 46

Carbonate Major ion Field (63786), 1948 (na2) 4, 10

2-Chloro-4-isopropylamino6-amino-s-triazine 

{Deethylatrazine}

Degradate 2033 (04040), 2060 (04040) 6

Chromium, total Trace element 1948 (01030), TML (01030) 11, 12

Iron, total Trace element 1948 (01046), TML (01046) 11, 12

Metalaxyl Pesticide 2033 (61596), 32060 (50359) 6

Oxygen, dissolved dissolved gas Field (00300), CFC (62971) 4, 14

pH Water-quality indicator Field (00400), 1948 (00403) 4

Specific conductance Water-quality indicator Field (00095), 1948 (90095) 4

Tebuthiuron Pesticide 2033 (82670), 2060 (82670) 6

1,2,3-Trichloropropane 

(1,2,3-TCP)

VOC MWH (77443), 32020 (77443) 8, 45

1

 Results for argon by LLNL in their units can be converted to milligrams per liter by multiplying the value by 1,784 based on the density of argon gas at 

standard temperature and pressure.

2

 Bicarbonate and carbonate concentrations (non-preferred method) were calculated from the laboratory measured alkalinity and pH values using the advanced 

speciation method (http://or.water.usgs.gov/alk/methods.html).

3

 Not detected in Upper Santa Ana Watershed samples by this analytical schedule.

4

 Constituent does not appear on this table because the constituent was not detected by the analytical schedule(s) for which results are reported by this table.
Table A3. Constituents detected in field blanks collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and 

Assessment (GAMA) study, California, November 2006 to March 2007.

[Abbreviations: E, estimated value; pCi/L, picocuries per liter; mg/L, milligrams per liter; μg/L, micrograms per liter; –, not detected; NWQL, USGS National 

Water Quality Laboratory]

Constituent

Slow schedule Fast, intermediate, and topical schedules

Number of 

field blank 

detections/

analyses

Maximum 

concentration 

detected in 

field blanks

Number of 

ground-water 

detections 

censored

Number of 

field blank 

detections/

analyses

Maximum 

concentration 

detected in 

field blanks

Number of 

ground-water 

detections 

censored

Organic constituents

Dissolved organic carbon (mg/L) 2/3 1.4 21 0/0 – 13

N-Nitrosodimethylamine (NDMA) (μg/L) 2/3 0.015 2(all) 0/0 – 0

Volatile organic compounds (μg/L) [unfiltered]

1,2,4-Trimethylbenzene 1/3 E0.035 0 0/5 – 0

Acetone 1/3 E4.0 0 0/5 – 0

2-Butanone (MEK, Methyl ethyl ketone) 1/3 13 0 0/5 – 0

m- and p-Xylene 1/3 E0.020 0 0/5 – 0

Toluene 1/3 E0.010 1(all) 2/5 E0.020 4(all)

Pesticides (μg/L) [filtered]

Atrazine 0/3 – 0 1/4 E0.005 0

Simazine 0/3 – 0 1/4 E0.004 1

Potential wastewater indicators (μg/L) [unfiltered]2

d-Limonene 0/3 – 0 1/4 E0.030 1

Inorganic constituents

Calcium (mg/L) 0/3 – 0 1/2 E0.013 0

Total nitrogen (mg/L) 0/3 – 0 1/2 0.14 0

Trace elements (μg/L)

Aluminum 0/3 – 0 1/2 E1.2 0

Barium 0/3 – 0 1/2 E0.040 0

Chromium 0/3 – 0 1/2 E0.10 0

Copper 0/3 – 0 2/2 1.8 15

Lead 0/3 – 0 2/2 0.7 16

Mercury 1/3 E0.0094 0 0/0 – 0

Zinc 1/3 0.34 2 2/2 3.55 14

Arsenic (TML)3 1/3 2.5 0 0/0 – 0

Iron (TML)3 2/3 4 0 0/0 – 0

Radioactive constituents( pCi/L)

Radium-226 2/2 E0.019 7 0/0 – 0

Radium-228 2/2 E0.080 5 0/0 – 0

1

 Equipment and sampling method identical for all DOC sampling. Blanks collected at slow wells are equally applicable to fast, intermediate and topical 

wells.

2

 An additional 18 potential wastewater indicators were detected in a blank that was subsequently determined to have been cross-contaminated at the NWQL.

3

 Analyses made by U.S. Geological Survey Trace Metal Laboratory.

Table A3 101
102 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Table A4A. Quality-control summary of replicate analyses of organic and inorganic compounds detected in samples collected for 

the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to 

March 2008.

[Abbreviations: RSD, relative standard deviation in percent; np, no pairs with RSDs greater than 20 percent; μg/L, micrograms per liter; mg/L, milligrams per 

liter; E, estimated; V, reported but not used in summary statistics; <, less than; –, not detected]

Constituent

Number of RSDs 

greater than 20 percent/

number of replicate 

pairs

Maximum RSD 

(percent)

Median of RSDs 

greater than zero 

(percent)

Concentrations for 

replicates with RSD 

greater than 20 percent 

(environmental, replicate) 

(μg/L)

Organic constituents

 Volatile organic compounds from schedule 2020 (μg/L)

1,2,4-Trimethylbenzene 1/8 119 61 (E0.05, 0.59)

All other VOCs 0/8 18 2 np

Pesticide and pharmaceutical compounds from schedules 2033, 2060 and 2080 (μg/L)

Pesticide compounds 0/7 16 3 np

Pharmaceutical compounds 0/7 3 3 np

Potential wastewater indicators from schedule 4433 (μg/L)

Caffeine 1/7 84 84 (E0.09, E0.02)

3,4-Dichlorophenyl isocyanate 1/7 25 25 (E0.33, E0.23)

Phenol 1/7 89 89 (E0.099, 0.023)

Tetrachloroethene 1/7 104 104 (E0.09, E0.01)

All other potential wastewater indicators 0/7 – – np

Dissolved organic carbon 0/4 1 <1 np

Inorganic constituents

Major ions, total dissolved solids, and silica 

(mg/L)

0/4 7 <1 np

Trace elements (μg/L)

Copper 1/4 21 3 (V1.64, 2.52)

Nickel 1/4 33 9 (E0.03, 0.06)

Zinc 1/4 20 3 (7.64, 11.44)

All other trace elements 0/4 14 <1 np

 USGS Trace Metals Laboratory (μg/L)

Iron, total 0/3 6 2 np

Iron(II) 0/3 2 0 np

Arsenic, total 0/3 13 0 np

Arsenic(III) 0/3 – – np

Chromium, total 0/3 – – np

Chromium(VI) 0/3 – – np

Nutrients (mg/L) 0/4 4 <1 np
Table A4B 103

Table A4B. Quality-control summary for replicate analyses of constituents of special interest, stable isotopes, dissolved gases, 

noble gases, and radioactive constituents detected in samples collected for the Upper Santa Ana Watershed Groundwater Ambient 

Monitoring and Assessment (GAMA) study, California, November 2006 to March 2008.

[Abbreviations: RSD, relative standard deviation in percent; np, no pairs with RSDs greater than 20 percent; μg/L, micrograms per liter; per mil, per thousand; 

mg/L, milligrams per liter; cm3 STP/g, cubic centimeters of gas at standard temperature and pressure per gram of water; pCi/L, picocuries per liter; <, less than; 

–, not detected]

Constituent

Number of RSDs 

greater than 20 

percent/number of 

replicate pairs

Maximum RSD 

(percent)

Median of RSDs 

greater than zero 

(percent)

Concentrations for 

replicates with RSD greater 

than 20 percent 

(environmental, replicate) 

(μg/L)

Constituents of special interest (μg/L)

Perchlorate 0/8 5 0 np

1,2,3-Trichloropropane 0/3 <1 <1 np

Stable isotopes of water, dissolved nitrate, and dissolved nitrogen gas (per mil)

δ2H 0/8 1 <1 np

δ18O 0/8 <1 <1 np

N15/N14 in nitrate 0/3 2 2 np

O18/O16 in nitrate 0/3 8 5 np

N15/N14 in nitrogen gas 4/54 35 5 (0.30, 0.49), (0.19, 0.27), 

(0.54, 0.39), (0.65, 0.89)

Dissolved gases (mg/L)

Dissolved Nitrogen 0/3 1 <1 np

Dissolved Argon 0/3 <1 <1 np

Dissolved Oxygen 1/3 27 11 (4.09, 5.99)

Dissolved Carbon dioxide 0/3 6 <1 np

Dissolved Methane 0/3 2 <1 np

Noble gases (cm3

 STP/g)

Helium-3/Helium-4 0/6 2 1 np

Helium-4 1/6 58 <1 (4.97 × 10-7, 1.20 × 10-6)

Argon 0/6 3 <1 np

Krypton 1/6 42 2 (1.40 × 10-7, 2.59 × 10-7)

Neon 1/6 61 <1 (1.24 × 10-6, 3.11 × 10-6)

Xenon 1/6 34 <1 (1.24 × 10-8, 2.32 × 10-8)

Radioactive constituents

Radium-226 (pCi/L) 1/2 26 21 (0.087, 0.060)

Radium-228 (pCi/L) 1/2 28 19 (0.611, E0.408)

Alpha radioactivity, 72-hour count (pCi/L) 0/2 13 9 np

Alpha radioactivity, 30-day count (pCi/L) 0/2 – – np

Beta radioactivity, 72-hour count (pCi/L) 1/2 53 28 (E1.35, E2.96)

Beta radioactivity, 30-day count (pCi/L) 1/2 20 12 (E2.7, E3.6)

Radon-222 (pCi/L) 0/2 5 <1 np

Tritium (pCi/L) 0/3 2 0 np

δ13C (per mil) 0/3 2 <1 np

Carbon-14 (percent modern) 0/3 <1 <1 np
104 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Table A5A. Quality-control summary of matrix-spike recoveries of volatile organic compounds (VOCs) in 

samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment 

(GAMA) study, California, November 2006 to March 2007.

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number 

of spike 

samples

Recovery (percent)

Minimum Maximum Median

Acetone 7 99 110 105

Acrylonitrile 7 98 110 103

Benzene 7 95 109 100

Bromobenzene 7 87 109 103

Bromochloromethane 7 104 115 109

Bromodichloromethane1 7 97 114 107

Bromoform (tribromomethane)1 7 98 110 101

2-Butanone (ethyl methyl ketone) 7 92 106 100

Butylbenzene (n-Butylbenzene) 7 80 97 91

sec-Butylbenzene 7 91 115 99

tert-Butylbenzene 7 102 120 108

Carbon disulfide 7 68 90 75

Carbon tetrachloride (tetrachloromethane)1 7 97 116 106

Chlorobenzene 7 83 108 100

Chloroethane 7 94 117 101

Chloroform (trichloromethane)1 7 89 119 113

Chloromethane1 7 90 122 116

3-Chloro-1-propene 7 110 136 116

2-Chlorotoluene 7 87 111 103

4-Chlorotoluene 7 87 115 103

Dibromochloromethane1 7 95 107 103

1,2-Dibromo-3-chloropropane (DBCP)1 7 90 108 104

1,2-Dibromoethane (EDB) 7 95 109 103

Dibromomethane 7 92 115 109

1,2-Dichlorobenzene (o-dichlorobenzene)1 7 88 109 106

1,3-Dichlorobenzene 7 89 113 105

1,4-Dichlorobenzene (p-dichlorobenzene)1 7 90 111 101

trans-1,4-Dichloro-2-butene 7 90 101 97

Dichlorodifluoromethane (CFC-12)1 7 64 104 81

1,1-Dichloroethane1 7 102 116 109

1,2-Dichloroethane1 7 99 116 109

1,1-Dichloroethylene (DCE)1 7 81 104 93

cis-1,2-Dichloroethylene1 7 91 111 101

trans-1,2-Dichloroethylene1 7 96 117 104

Dichloromethane (methylene chloride)1 7 90 106 103

1,2-Dichloropropane1 7 87 105 100

1,3-Dichloropropane 7 92 110 106

2,2-Dichloropropane 7 81 89 84

1,1-Dichloropropene 7 85 109 96

cis-1,3-Dichloropropene 7 74 94 90

trans-1,3-Dichloropropene 7 84 96 93

Diethyl ether 7 80 107 100

Diisopropyl ether 7 84 104 98

Ethylbenzene 7 83 111 103

Ethyl tert-butyl ether (ETBE, tert-butyl ethyl ether) 7 75 100 93

Ethyl methacrylate 7 71 96 92

o-Ethyl toluene (2-Ethyltoluene) 7 83 106 96

Hexachlorobutadiene 7 74 92 81

Hexachloroethane 7 96 107 102

2-Hexanone (n-Butyl methyl ketone) 7 95 109 107

Isopropylbenzene (cumene) 7 89 119 106

4-Isopropyl-1-methylbenzene (p-isopropyltoluene) 7 88 110 99

Methyl acrylate (Methyl-2-propenoate) 7 93 104 99

Methyl acrylonitrile 7 104 115 106
Constituent

Number 

of spike 

samples

Recovery (percent)

Minimum Maximum Median

Methyl bromide (bromomethane) 7 107 141 133

Methyl tert-butyl ether (MTBE)1 7 75 100 96

Methyl iodide (iodomethane) 7 94 127 121

Methyl methacrylate 7 70 100 93

4-Methyl-2-pentanone (MIBK, isobutyl methyl ketone) 7 87 102 98

Methyl tert-pentyl ether 7 81 100 98

Naphthalene 7 80 110 102

n-Propylbenzene 7 87 115 99

Styrene 7 85 106 99

1,1,1,2-Tetrachloroethane 7 93 111 107

1,1,2,2-Tetrachloroethane 7 93 109 103

Tetrachloroethene (PCE)1 7 89 113 100

Tetrahydrofuran 7 90 118 109

1,2,3,4-Tetramethylbenzene 7 77 110 103

1,2,3,5-Tetramethylbenzene (isodurene) 7 85 113 108

Toluene2 7 90 108 101

1,2,3-Trichlorobenzene 7 85 113 105

1,2,4-Trichlorobenzene 7 77 106 95

1,1,1-Trichloroethane (TCA)1 7 96 115 111

1,1,2-Trichloroethane 7 96 113 106

Trichloroethene (TCE)1 7 81 105 100

Trichlorofluoromethane (CFC-11)1 7 68 123 108

1,2,3-Trichloropropane (1,2,3-TCP) 7 96 111 103

1,1,2-Trichlorotrifluoroethane (CFC-113)1 7 71 96 82

1,2,3-Trimethylbenzene 7 95 108 105

1,2,4-Trimethylbenzene1 7 94 119 105

1,3,5-Trimethylbenzene 7 94 115 101

Vinyl bromide (Bromoethene) 7 106 128 115

Vinyl chloride 7 94 138 112

m- and p-Xylene 7 96 115 104

o-Xylene 7 81 106 99

1

 Constituents detected in ground-water samples.

2

 Detections of toluene in ground-water samples could be entirely attributed to contamination.

Table A5A. Quality-control summary of matrix-spike recoveries of volatile organic compounds (VOCs) in 

samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment 

(GAMA) study, California, November 2006 to March 2007.—Continued

[Acceptable recovery range is between 70 and 130 percent]

Table A5A 105
106 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

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

(lab analytical schedule 2060) in samples collected for the Upper Santa Ana Watershed Groundwater Ambient 

Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number 

of spike 

samples

Recovery (percent)

Minimum Maximum Median

Acifluorfen 6 31 85 67

Aldicarb 6 24 76 55

Aldicarb sulfone 6 29 79 48

Aldicarb sulfoxide 6 88 116 98

Atrazine1 6 82 102 93

Bendiocarb 6 67 102 79

Benomyl 6 63 86 75

Bensulfuron-methyl 6 94 121 108

Bentazon 6 48 75 61

Bromacil1 6 72 142 107

Bromoxynil1 6 32 55 44

Caffeine 6 68 106 89

Carbaryl 6 82 105 91

Carbofuran 6 79 93 90

Chloramben methyl ester 6 76 113 88

Chlorimuron-ethyl 6 76 109 91

2-Chloro-4-isopropylamino-6-amino-s-triazine 

(Deethylatrazine, CIAT)1

6 43 82 66

2-Choro-6-ethylamino-4-amino-s-triazine 

(Deisopropylatrazine, CEAT)1

6 56 87 77

3-(4-Chlorophenyl)-1-methyl urea1 6 47 84 68

Clopyralid 6 32 72 54

Cycloate 6 64 98 79

2,4-D (2,4-Dichlorophenoxyacetic acid) 6 64 90 77

2,4-D methyl ester (2,4-Dichlorophenoxyacetic 

acid methyl ester)

6 77 102 81

2,4-DB (4-(2,4-Dichlorophenoxy)butyric acid) 6 36 58 54

DCPA (Dacthal) monoacid 6 56 87 75

Dicamba 6 44 72 57

Dichlorprop 6 60 87 73

Dinoseb1 6 36 72 56

Diphenamid1 6 84 102 90

Diuron1 6 84 98 89

Fenuron 6 76 105 87

Flumetsulam 6 52 128 110

Fluometuron 6 84 105 94

2-Hydroxy-4-isopropylamino-6-ethylamino-s-triazine 

(Hydroxyatrazine)1

6 84 103 97

3-Hydroxy carbofuran 6 70 113 88

Imazaquin 6 79 109 92

Imazethapyr1 6 78 117 93

Imidacloprid 6 51 123 100

Linuron 6 80 94 89

MCPA (2-Methyl-4-chlorophenoxyacetic acid) 6 52 76 69

MCPB (4-(2-Methyl-4-chlorophenoxy) butyric acid) 6 36 58 50

Metalaxyl 6 89 109 90

Methiocarb 6 78 97 89

Methomyl 6 90 110 97

Metsulfuron methyl 6 28 124 70

Neburon 6 84 109 90

Nicosulfuron 6 76 225 134

Norflurazon1 6 87 109 97

Oryzalin 6 71 98 82
Constituent

Number 

of spike 

samples

Recovery (percent)

Minimum Maximum Median

Oxamyl 6 72 121 89

Picloram 6 54 729 62

Propham 6 86 112 95

Propiconazole 6 76 113 94

Propoxur (Baygon) 6 88 103 93

Siduron1 6 88 107 94

Sulfometuron methyl 6 84 121 106

Tebuthiuron1 6 85 129 103

Terbacil 6 71 125 97

Triclopyr 6 56 92 81

1

 Constituents detected in ground-water samples.

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

(lab analytical schedule 2060) in samples collected for the Upper Santa Ana Watershed Groundwater Ambient 

Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued

[Acceptable recovery range is between 70 and 130 percent]

Table A5B 107
108 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Table A5C. Quality-control summary of matrix-spike recoveries of pesticides and pesticide degradates (lab 

analytical schedule 2033) in samples collected for the Upper Santa Ana Watershed Groundwater Ambient 

Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number 

of spike 

samples

Recovery (percent)

Minimum Maximum Median

Acetochlor 6 86 112 98

Alachlor 6 94 108 99

Atrazine1 6 93 103 97

Azinphos-methyl 6 80 118 87

Azinphos-methyl-oxon 6 38 73 57

Benfluralin 6 47 71 56

Carbaryl 6 95 127 113

Carbofuran 6 88 100 95

2-Chloro-2,6-diethylacetanilide 6 87 101 93

4-Chloro-2-methylphenol 6 58 73 64

Chlorpyrifos 6 82 97 89

Chlorpyrofos, oxygen analog 6 10 55 22

Cyanazine 6 78 106 95

Cyfluthrin 6 35 61 37

λ-Cyhalothrin 6 25 45 27

Cypermethrin 6 34 65 38

DCPA (Dacthal)1 6 91 107 97

Deethylatrazine (2-Chloro-4-isopropylamino-6-

amino-s-triazine)1

6 41 52 47

Desulfinylfipronil1 6 76 103 87

Desulfinylfipronil amide1 6 55 109 77

Diazinon 6 88 97 94

Diazon oxon 6 57 100 75

3,4-Dichloroaniline1 6 72 85 78

3,5-Dichloroaniline 6 76 91 86

Dichlorvos 6 10 27 17

Dicrotophos 6 28 39 35

Dieldrin 6 84 120 99

2,6-Diethylaniline 6 89 96 93

Dimethoate 6 26 41 35

Disulfoton 6 44 82 64

Disulfoton sulfone 6 72 109 96

α-Endosulfan 6 76 87 80

Endosulfan sulfate 6 71 92 84

EPTC 6 84 95 93

Ethion 6 61 91 72

Ethion monoxon 6 58 109 87

Ethoprop 6 77 130 108

2-Ethyl-6-methylaniline 6 84 95 91

Fenamiphos 6 52 127 75

Fenamiphos sulfone 6 47 95 61

Fenamiphos sulfoxide 6 34 43 37

Fipronil1 6 63 118 82

Fipronil sulfide1 6 65 95 76

Fipronil sulfone 6 51 81 61

Fonofos 6 81 96 87

Hexazinone 6 54 84 65

Iprodione 6 67 78 74

Isofenphos 6 83 118 98

Malaoxon 6 65 103 88

Malathion 6 88 106 96

Metalaxyl1 6 93 101 96

Methidathion 6 75 105 93

Metolachlor1 6 97 110 105
Constituent

Number 

of spike 

samples

Recovery (percent)

Minimum Maximum Median

Metribuzin 6 70 85 79

Molinate 6 87 102 96

Myclobutanil 6 76 104 88

1-Naphthol 6 14 36 20

Oxyfluorfen 6 42 56 48

Paraoxon-methyl 6 32 54 43

Parathion-methyl 6 62 93 80

Pendimethalin1 6 59 120 77

cis-Permethrin 6 37 71 43

Phorate 6 57 80 70

Phorate oxygen analog 6 49 127 86

Phosmet 6 12 22 17

Phosmet oxon 6 9 18 11

Prometon1 6 84 100 90

Prometryn 6 87 112 102

Pronamide 6 90 102 93

Propanil 6 87 134 101

Propargite 6 59 82 66

cis-Propiconazole 6 20 26 23

trans-Propiconazole 6 57 82 67

Simazine1 6 86 110 95

Tebuconazole 6 48 69 57

Tebuthiuron1 6 74 145 95

Tefluthrin 6 25 47 29

Terbufos 6 74 135 90

Terbufos oxygen analog sulfone 6 51 91 66

Terbuthylazine 6 95 108 98

Thiobencarb 6 107 120 118

Tribufos 6 41 80 55

Trifluralin 6 52 77 61

1

 Constituents detected in ground-water samples.

Table A5C. Quality-control summary of matrix-spike recoveries of pesticides and pesticide degradates (lab 

analytical schedule 2033) in samples collected for the Upper Santa Ana Watershed Groundwater Ambient 

Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.—Continued

[Acceptable recovery range is between 70 and 130 percent]

Table A5C 109
110 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Table A5D. Quality-control summary of matrix-spike recoveries of pharmaceutical compounds in samples 

collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, 

California, November 2006 to March 2007.

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number 

of spike 

samples

Recovery (percent)

Minimum Maximum Median

Acetaminophen1 6 55 113 64

Caffeine1 6 78 108 80

Carbamazepine1 6 70 115 85

Codeine 6 81 107 92

Cotinine 6 80 94 89

Dehydronifedipine 6 47 92 72

Diltiazem 6 3 54 15

1,7-Dimethylxanthine1 6 62 95 74

Diphenhydramine 6 29 65 55

Salbutamol (albuterol) 6 60 129 77

Sulfamethoxazole 6 17 62 52

Thiabendazole 6 16 80 72

Trimethoprim 6 85 106 94

Warfarin 6 19 62 44

1

 Constituents detected in ground-water samples.
Table A5E 111

Table A5E. Quality-control summary of matrix-spike recoveries of wastewater indicator compounds in samples 

collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, 

California, November 2006 to March 2007.

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number 

of spike 

samples

Recovery (percent)

Minimum Maximum Median

Acetophenone 6 56 83 64

Acetyl hexamethyl tetrahydronaphthalene (AHTN) 6 63 85 75

Anthracene 6 58 76 63

Anthraquinone 6 49 86 64

Atrazine 6 62 78 74

Benzo[a]pyrene 6 51 68 57

Benzophenone 6 51 81 66

Bisphenol A 6 71 98 75

bis(2-Ethylhexyl) phthalate 6 0 379 83

Bromacil 6 54 77 67

Bromoform (tribromomethane) 6 49 65 58

3-tert-Butyl-4-hydroxy anisole (BHA) 6 28 57 38

Caffeine 6 60 74 68

Camphor 6 60 79 66

Carbaryl 6 47 89 66

Carbazole 6 67 78 71

Chlorpyrifos 6 61 76 67

Cholesterol 6 36 64 47

3-beta-Coprostanol 6 40 73 55

Cotinine 6 24 44 33

para-Cresol 6 54 76 65

4-Cumylphenol 6 63 73 68

N,N-diethyl-m-toluamide (DEET) 6 54 82 68

1,4-Dichlorobenzene 6 37 68 49

3,4- Dichlorophenyl isocyanate 6 39 233 90

Dichlorvos 6 45 76 56

Diethyl phthalate 6 63 84 73

2,6-Dimethylnaphthalene 6 57 74 65

Diazinon 6 55 62 62

4-Nonylphenol diethoxylates 6 58 90 68

4-Octylphenol diethoxylates 6 52 95 62

Nonylphenol, monoethoxylates (total) 6 62 85 71

4-Octylphenol monoethoxylates 6 46 70 56

Fluoranthene 6 67 86 75

Hexahydrohexamethylcyclopentabenzopyran (HHCB) 6 64 85 71

Indole 6 50 68 60

Isoborneol 6 57 76 65

Isophorone 6 54 77 60

Isopropylbenzene 6 18 58 32

Isoquinoline 6 5 59 51

d-Limonene 6 7 44 21

Menthol 6 53 84 69

Metalaxyl 6 64 80 67

3-Methyl-1(H)-indole (Skatole) 6 57 77 67

5-Methyl-1H-benzotriazole 6 43 79 56

1-Methylnaphthalene 6 60 73 66

2-Methylnaphthalene 6 55 71 65

Methyl salicylate 6 65 89 72

Metolachlor 6 59 79 68

Naphthalene 6 62 71 67

para-Nonylphenol (total) 6 68 87 74

4-n-Octylphenol 6 51 75 65

4-tert-Octylphenol 6 66 83 73
112 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

Constituent

Number 

of spike 

samples

Recovery (percent)

Minimum Maximum Median

Pentachlorophenol 6 52 100 74

Phenanthrene 6 64 78 68

Phenol 6 55 80 62

Prometon 6 52 75 61

Pyrene 6 65 80 71

beta-Sitosterol 3 59 66 61

beta-Stigmastanol 4 53 68 61

2,2',4,4'- Tetrabromodiphenyl ether 1 9 9 9

Tetrachloroethylene (PCE) 6 11 45 20

Tributyl phosphate 6 50 76 61

Triclosan 6 61 98 71

Triethyl citrate (ethyl citrate) 6 57 81 65

Triphenyl phosphate 6 57 82 65

Tris(2-butoxyethyl)phosphate 6 51 88 56

Tris(2-chloroethyl)phosphate 6 61 76 66

Tris(dichlorisopropyl)phosphate 6 56 84 66

Table A5E. Quality-control summary of matrix-spike recoveries of wastewater indicator compounds in samples 

collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, 

California, November 2006 to March 2007.—Continued

[Acceptable recovery range is between 70 and 130 percent]
Table A5F 113

Table A5F. Quality-control summary of matrix-spike recoveries of 1,4-Dioxane, 1,2,3-Trichloropropane, and 

N-Nitrosodimethylamine in samples collected for the Upper Santa Ana Watershed Groundwater Ambient 

Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007.

[Acceptable recovery range is between 70 and 130 percent]

Constituent

Number 

of spike 

samples

Recovery (percent)

Minimum Maximum Median

1,4-Dioxane 1 69 69 69

1,2,3-Trichloropropane (TCP)1 2 90 95 93

N-Nitrosodimethylamine (NDMA)2 2 98 99 99

1

 Constituent detected in ground-water samples.

2

 The constituent detected in one ground-water sample could be attributed to contamination.

Table A5G. Quality-control summary of matrix-spike recoveries of radioactive constituents in samples collected 

for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, 

November 2006 to March 2007.

[Acceptable recovery range is between 70 and 130 percent. All constituents were detected in ground-water samples]

Constituent

Number 

of spike 

samples

Recovery (percent)

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Gross-alpha radioactivity, 72 hr count 2 84 92 88

Gross-alpha radioactivity, 30 day count 2 90 114 102

Gross-beta radioactivity, 72 hr count 2 93 101 97

Gross-beta radioactivity, 30 day count 2 91 93 92

Radium-226 1 96 96 96

Radium-228 1 106 106 106
114 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program Table A6. Quality-control summary for surrogate recoveries of volatile organic compounds, pesticides and pesticide degradates, pharmaceutical compounds, wastewater- indicator compounds, and constituents of special interest in samples collected for the Upper Santa Ana Watershed Groundwater Ambient Monitoring and Assessment (GAMA) study, California, November 2006 to March 2007. [MWH, Montgomery Watson-Harza Laboratory (special interest constituents); VOC, volatile organic compound; 1,2,3-TCP, 1,2,3-trichloropropane; NDMA, 

N-nitrosodimethylamine]

Surrogate Analytical schedule Constituent or constituent class analyzed Number of blank analyses Median recovery in blanks (percent) Number of surrogate recoveries Number of sample analyses Median recovery in samples (percent) Number of surrogate recoveries Below 70 percent in blanks Above 130 percent in blanks Below 70 percent in samples Above 130 percent in samples

1-Bromo-4-

fluorobenzene

2020 VOC 8 75 0 0 99 73 22 0

1,2-Dichloroethane-d4 2020 VOC 8 120 0 2 99 128 0 43

Toluene-d8 2020 VOC 8 96 0 0 99 96 0 0

Diazinon-d10 2033 Pesticide 7 103 0 0 92 102 5 0

alpha-HCH-d6 2033 Pesticide 7 92 0 0 92 90 0 0

Barban 2060 Polar pesticide 6 86 0 0 92 86 3 0

Caffeine-13

C 2060 Polar pesticide 6 108 0 1 92 94 12 2

2,4,5-T 2060 Polar pesticide 6 74 1 0 92 70 45 0

Ethyl nicotinate-d4 2080 Pharmaceutical 7 93 0 0 92 90 0 0

Carbamazepine-d10 2080 Pharmaceutical 7 100 0 0 92 103 0 4

Bisphenol A-d3 4433 Potential wastewater-indicator 7 43 5 0 95 73 44 0

Caffeine-13

C 4433 Potential wastewater-indicator 7 62 5 0 95 78 31 0

Decafluorobiphenyl 4433 Potential wastewater-indicator 7 53 7 0 95 61 79 0

Fluoranthene-d10 4433 Potential wastewater-indicator 7 91 2 0 95 90 7 0

Toluene-d8 MWH 1,2,3-TCP 3 101 0 0 32 101 0 0

NDMA-d6 MWH NDMA 3 95 1 0 32 92 3 0

Nitrobenzene-d5 MWH 1,4-Dioxane 3 78 0 0 32 76 5 0

Terphenyl-d14 MWH 1,4-Dioxane 3 63 2 0 32 56 25 0
Table A7A. Quality-control summary for laboratory “set blanks” for pharmaceutical 

compounds corresponding to analyses of samples collected for the Upper Santa Ana 

Watershed Ground-Water Ambient Monitoring and Assessment (GAMA) study, California, 

November 2006 to March 2007.

[μg/L, micrograms per liter; E, estimated value]

Constituent

Number of 

detections in 

20 set blank 

analyses

Maximum 

concentration 

detected in set 

blank samples 

(μg/L) 

Minimum 

concentration 

detected in 

ground-water 

samples (μg/L)

Number of 

groundwater 

samples 

censored

Acetaminophen1 2 E0.002 E0.015 0

Albuterol 1 E0.0002 Not detected 0

Caffeine1 4 E0.004 E0.011 0

Carbamazepine1 1 E0.0003 0.032 0

Codeine 0

Cotinine 8 E0.017 Not detected 0

Dehydronifedipine 1 E0.0004 Not detected 0

Diltiazem 0

1,7-dimethylxanthine1 0

Diphenhydramine 1 E0.0005 Not detected 0

Sulfamethoxazole 0

Thiabendazole 1 E0.0003 Not detected 0

Trimethoprim 1 E0.0003 Not detected 0

Warfarin 0

1

 Constituents detected in ground-water samples.

Table A7B. Quality-control summary for laboratory “set spikes” for pharmaceutical 

compounds corresponding to analyses of samples collected for the Upper Santa Ana 

Watershed Ground-Water Ambient Monitoring and Assessment (GAMA) study, California, 

November 2006 to March 2007.

[Acceptable recovery range is between 70 and 130 percent]

Constituent 

Number of 

set spike 

samples

Recovery (percent)

Minimum Maximum Median

Acetaminophen1 20 72 143 99

Albuterol 20 76 126 104

Caffeine1 20 85 135 103

Carbamazapine1 20 63 120 96

Codeine 20 67 100 85

Cotinine 20 87 114 96

Dehydronifedipine 20 49 98 70

Diltiazem 20 1 51 12

1,7-dimethylxanthine1 20 77 133 108

Diphenhydramine 20 49 79 57

Sulfamethoxazole 20 47 105 67

Thiabendazole 20 75 109 91

Trimethoprim 20 73 112 100

Warfarin 20 10 55 24

1

 Constituents detected in ground-water samples.

Table A7A 115
116 Ground-Water Quality Data, Upper Santa Ana Watershed Study Unit, November 2006 to March 2007: California GAMA Program

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Kent and Belitz—Ground-Water Quality Data in the Upper Santa Ana Watershed Study Unit, November 2006-March 2007: Results from the California GAMA Program—Data Series 404

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