U.S. Department of the Interior

U.S. Geological Survey

Data Series 742

Prepared in cooperation with the California State Water Resources Control Board

Groundwater-Quality Data in the Santa Barbara Study Unit, 

2011: Results from the California GAMA Program

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

GOLETA

CARPINTERIA

MONTECITO

SANTA BARBARA

FOOTHILL

Mission Creek

Santa Ynez River

El Estero

Goleta

Slough

Laguna

Blanca

West Beach

Santa Ynez Mts

PACIFIC OCEAN

154

101

SANTA

BARBARA

CO

VENTURA

CO

Goleta Montecito

Carpinteria

Santa

Barbara
Cover photographs:

Top right: Bridge over Rincon Creek in Carpinteria, California. (Photograph taken by 

Tracy Davis, U.S. Geological Survey.)

Bottom right: Well facing Santa Ynez Mountains, California. (Photograph taken by 

Carmen Burton, U.S. Geological Survey.)
Groundwater-Quality Data in the Santa Barbara Study 

Unit, 2011: Results from the California GAMA Program

By Tracy A. Davis, Justin T. Kulongoski, and Kenneth Belitz

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

Prepared in cooperation with the California State Water Resources Control Board 

Data Series 742

U.S. Department of the Interior

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

SALLY JEWELL, Secretary

U.S. Geological Survey

Suzette M. Kimball, Acting Director

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

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reproduce any copyrighted materials contained within this report.

Suggested citation:

Davis, T.A., Kulongoski, J.T., and Belitz, Kenneth, 2013, Groundwater-quality data in the Santa Barbara study unit, 

2011—Results from the California GAMA Program: U.S. Geological Survey Data Series 742, 72 p.
iii

Contents

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

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

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

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

Methods ..........................................................................................................................................................6

Study Design..........................................................................................................................................6

Sample Collection and Analysis.........................................................................................................7

Data Reporting.......................................................................................................................................7

Quality-Assurance Methods...............................................................................................................9

Water-Quality Results ..................................................................................................................................9

Quality-Control Results ........................................................................................................................9

Comparative Benchmarks...................................................................................................................9

Groundwater-Quality Data ................................................................................................................10

Water-Quality Indicators .........................................................................................................11

Organic Constituents.................................................................................................................11

Constituents of Special Interest..............................................................................................11

Inorganic Constituents..............................................................................................................11

Isotopic Tracers .........................................................................................................................12

Radioactive Constituents..........................................................................................................13

Future Work ..................................................................................................................................................13

Summary .......................................................................................................................................................13

Acknowledgments.......................................................................................................................................14

References Cited..........................................................................................................................................14

Appendix .......................................................................................................................................................49
iv

Tables

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

Santa Barbara study unit, January to February 2011, California GAMA Priority 

Basin Project. ................................................................................. 20

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

the Santa Barbara study unit, January to February 2011, California GAMA 

Priority Basin Project. ........................................................................ 21

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

and reporting information for the USGS National Water Quality Laboratory 

Schedule 2020. ................................................................................. 22

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

benchmarks, and reporting information for the USGS National Water Quality 

Laboratory Schedule 2003. .................................................................. 26

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

thresholds, and reporting information for the USGS National Water Quality 

Laboratory Schedule 2060. .................................................................. 28

3D. Pharmaceutical compounds, primary uses or sources, comparative benchmarks, 

and reporting information for the USGS National Water Quality Laboratory 

Schedule 2080. ................................................................................. 30

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

benchmarks, and reporting information for Weck Laboratories, Inc., City of 

Industry, California, analyses. ............................................................... 30

3F. Trace elements, comparative benchmarks, and reporting information for the 

USGS National Water Quality Laboratory Schedule 1948. .............................. 31

3G. Nutrients, comparative benchmarks, and reporting information for the 

USGS National Water Quality Laboratory Schedule 2755. .............................. 31

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

benchmarks, and reporting information for the USGS National Water Quality 

Laboratory Schedule 1948. .................................................................. 32

3I. Arsenic, chromium, and iron species, comparative benchmarks, and 

reporting information for the USGS Trace Metal Laboratory, Boulder, Colorado, 

analyses. ....................................................................................... 32

Figures

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

Santa Barbara study unit, California GAMA Priority Basin Project ..................... 3

2. Map showing the boundaries of California Department of Water Resources 

groundwater basins in the Santa Barbara study unit and the locations of 

counties, major cities, major roads, topographic features, and hydrologic 

features and geologic map of the Santa Barbara Coastal Plain showing 

major faults and hydrologic features, Santa Barbara study unit, California 

GAMA Priority Basin Project ............................................................... 5

3. Maps showing the distribution of the grid cells and the location of public-supply wells 

from the California Department of Public Health database, and the distribution of grid 

cells, the location of sampled grid and understanding wells, Santa Barbara study unit, 

California GAMA Priority Basin Project ................................................... 8
v

3J. Isotope tracers and radioactive constituents, comparative benchmarks, and 

reporting information for laboratory analyses.............................................. 33

3K. Dissolved gases and isotope tracers, comparison benchmarks, and reporting 

information for Lawrence Livermore National Laboratory. .............................. 33

4. Water-quality indicators in samples collected for the Santa Barbara study unit, 

January to February 2011, California GAMA Priority Basin Project...................... 34

5. Volatile organic compounds detected in samples collected for the 

Santa Barbara study unit, January to February 2011, California GAMA Priority 

Basin Project. ................................................................................. 36

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

Santa Barbara study unit, January to February 2011, California GAMA Priority 

Basin Project. ................................................................................. 38

7. Perchlorate detected in the samples collected for the Santa Barbara study unit, 

January to February 2011, California GAMA Priority Basin Project...................... 38

8. Trace elements detected in the samples collected for the Santa Barbara study 

unit, January to February 2011, California GAMA Priority Basin Project................ 39

9. Nutrients detected in samples collected for the Santa Barbara study unit, 

January to February 2011, California GAMA Priority Basin Project...................... 43

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

collected for the Santa Barbara study unit, January to February 2011, California 

GAMA Priority Basin Project. ............................................................... 44

11. Arsenic, chromium, and iron species detected in samples collected for the 

Santa Barbara study unit, January to February 2011, California GAMA Priority 

Basin Project. ................................................................................. 45

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

abundance detected in samples collected for the Santa Barbara study unit, 

January to February 2011, California GAMA Priority Basin Project...................... 46

13A. Radon-222 detected in samples collected for the Santa Barbara study unit, 

January to February 2011, California GAMA Priority Basin Project...................... 47

13B. Gross alpha and gross beta radioactivity detected in samples collected for the 

Santa Barbara study unit, January to February 2011, California GAMA Priority 

Basin Project. ................................................................................. 48

Tables—Continued
vi

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

Length

inch (in.) 2.54 centimeter (cm)

inch (in.) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 2.590 square kilometer (km2) 

Volume

ounce, avoirdupois (oz) 28.35 gram (g)

Mass

pound, avoirdupois (lb) 0.4536 kilogram (kg) 

SI to Inch/Pound

Multiply By To obtain

Length

centimeter (cm) 0.3937 inch (in.)

meter (m) 3.28 foot (ft)

kilometer (km) 0.6214 mile (mi)

Area

square kilometer (km2) 0.3861 square mile (mi2

)

Volume

liter (L) 1.057 quart (qt)

Mass

gram (g) 0.03527 ounce, avoirdupois (oz)

kilogram (kg) 2.205 pound avoirdupois (lb)

Radioactivity

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

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

°F=(1.8×°C)+32

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

°C=(°F – 32)/1.8

Vertical coordinate information is referenced to the North American Vertical Datum of 1988 

(NAVD 88).

Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83).

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

25°C).

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

or micrograms per liter (μg/L).

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

equivalent to parts per billion (ppb). 
vii

Abbreviations and Acronyms

AL-US action level (USEPA)

APE Alternate Place Entry Form program designed for USGS sampling

BBP Blind Blank Program

CAS Chemical Abstract Service (American Chemical Society)

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

CSU combined standard uncertainty

DWP Domestic Well Project (SWRCB)

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)

IBSP Inorganic Blind Sample Program (USGS)

HPLC high-performance liquid chromatography

LRL laboratory reporting level

LSD land surface datum

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

na not available

NAD normalized absolute difference

nc not collected

NFM National Field Manual (USGS)

NFQA National Field Quality Assurance Program (USGS)

NL-CA notification level (CDPH)

np no preference

nv no measured value or no value in category

NWIS National Water Information System (USGS)

PBP Priority Basin Project

PCFF Personal Computer Field Form program designed for USGS sampling

QA quality assurance

QC quality control
viii

RL reporting level

RPD relative percent difference

RSD relative standard deviation

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

SBFFB Santa Barbara fold and fault belt

SD standard deviation

SMCL-CA secondary maximum contaminant level (CDPH)

SMCL-US secondary maximum contaminant level (USEPA)

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

results)

ssLC sample-specific critical level

UV ultraviolet

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

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

the International Atomic Energy Agency)

Selected Terms and Symbols

α confidence level

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

and 1 atmosphere of pressure) per gram of water

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

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

as per mil

= equal to

> greater than 

≥ greater than or equal to

< less than

≤ less than or equal to

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

— not detected

p significant level

pH a measure of the acidity or basicity of a solution

pK1,2 negative logarithms of the acid dissociation constants for carbonic acid 

pKw negative logarithm of the acid dissociation constant of water

R result

± plus or minus

Abbreviations and Acronyms—Continued
ix

* value is at a concentration greater than benchmark level

** value is at a concentration greater than upper benchmark level

Organizations

BQS Branch of Quality Systems (USGS)

CDPH California Department of Public Health

CDPR California Department of Pesticide Regulation

CDWR California Department of Water Resources

LLNL Lawrence Livermore National Laboratory, Livermore, California

NAWQA National Water-Quality Assessment Program (USGS)

NELAP National Environmental Laboratory Accreditation Program

NWQL National Water Quality Laboratory (USGS)

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

SWRCB California State Water Resources Control Board

USEPA U.S. Environmental Protection Agency

USGS U.S. Geological Survey

Selected Chemical Names

CaCO3 calcium carbonate

CO3

2– carbonate

CFC chlorofluorocarbon

H2O water

HCl hydrochloric acid

HCO3

– bicarbonate

MTBE methyl tert-butyl ether

PCE perchloroethene (tetrachloroethene)

PVC polyvinyl chloride

SiO2 silicon dioxide

TDS total dissolved solids

THM trihalomethane

VOC volatile organic compound

Selected Terms and Symbols—Continued

Abstract 

Groundwater quality in the 48-square-mile Santa 

Barbara study unit was investigated by the U.S. Geological 

Survey (USGS) from January to February 2011, as part of the 

California State Water Resources Control Board (SWRCB) 

Groundwater Ambient Monitoring and Assessment (GAMA) 

Program’s Priority Basin Project (PBP). The GAMA-PBP 

was developed in response to the California Groundwater 

Quality Monitoring Act of 2001 and is being conducted in 

collaboration with the SWRCB and Lawrence Livermore 

National Laboratory (LLNL). The Santa Barbara study unit 

was the thirty-fourth study unit to be sampled as part of the 

GAMA-PBP.

The GAMA Santa Barbara study was designed to provide 

a spatially unbiased assessment of untreated-groundwater 

quality in the primary aquifer system, and to facilitate 

statistically consistent comparisons of untreated-groundwater 

quality throughout California. The primary aquifer system 

is defined as those parts of the aquifers corresponding to 

the perforation intervals of wells listed in the California 

Department of Public Health (CDPH) database for the Santa 

Barbara study unit. Groundwater quality in the primary aquifer 

system may differ from the quality in the shallower or deeper 

water-bearing zones; shallow groundwater may be more 

vulnerable to surficial contamination. 

In the Santa Barbara study unit located in Santa Barbara 

and Ventura Counties, groundwater samples were collected 

from 24 wells. Eighteen of the wells were selected by using a 

spatially distributed, randomized grid-based method to provide 

statistical representation of the study unit (grid wells), and six 

wells were selected to aid in evaluation of water-quality issues 

(understanding wells).

The groundwater samples were analyzed for organic 

constituents (volatile organic compounds [VOCs], 

pesticides and pesticide degradates, and pharmaceutical 

compounds); constituents of special interest (perchlorate 

and N-nitrosodimethylamine [NDMA]); naturally occurring 

inorganic constituents (trace elements, nutrients, major and 

minor ions, silica, total dissolved solids [TDS], alkalinity, 

and arsenic, chromium, and iron species); and radioactive 

constituents (radon-222 and gross alpha and gross beta 

radioactivity). Naturally occurring isotopes (stable isotopes 

of hydrogen and oxygen in water, stables isotopes of 

inorganic carbon and boron dissolved in water, isotope ratios 

of dissolved strontium, tritium activities, and carbon-14 

abundances) and dissolved noble gases also were measured to 

help identify the sources and ages of the sampled groundwater. 

In total, 281 constituents and water-quality indicators were 

measured.

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

and matrix spikes) were collected at up to 12 percent of 

the wells in the Santa Barbara study unit, and the results 

for these samples were used to evaluate the quality of the 

data for the groundwater samples. Blanks rarely contained 

detectable concentrations of any constituent, suggesting that 

contamination from sample collection procedures was not 

a significant source of bias in the data for the groundwater 

samples. Replicate samples generally were within the limits of 

acceptable analytical reproducibility. Matrix-spike recoveries 

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

approximately 82 percent of the compounds.

This study did not attempt to evaluate the quality of water 

delivered to consumers; after withdrawal from the ground, 

untreated groundwater typically is treated, disinfected, and 

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

Regulatory benchmarks apply to water that is served to the 

consumer, not to untreated groundwater. However, to provide 

some context for the results, concentrations of constituents 

measured in the untreated groundwater were compared with 

regulatory and non-regulatory health-based benchmarks 

established by the U.S. Environmental Protection Agency 

(USEPA) and CDPH and to non-regulatory benchmarks 

established for aesthetic concerns by CDPH. Comparisons 

between data collected for this study and benchmarks for 

drinking water are for illustrative purposes only and are 

not indicative of compliance or non-compliance with those 

benchmarks. All organic constituents and most inorganic 

constituents that were detected in groundwater samples from 

the 18 grid wells in the Santa Barbara study unit were detected 

at concentrations less than drinking-water benchmarks. 

Groundwater-Quality Data in the Santa Barbara Study 

Unit, 2011: Results from the California GAMA Program

By Tracy A. Davis, Justin T. Kulongoski, and Kenneth Belitz
2 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Of the 220 organic and special-interest constituents 

sampled for at the 18 grid wells, 13 were detected in 

groundwater samples; concentrations of all detected 

constituents were less than regulatory and non-regulatory 

health-based benchmarks. In total, VOCs were detected 

in 61 percent of the 18 grid wells sampled, pesticides 

and pesticide degradates were detected in 11 percent, and 

perchlorate was detected in 67 percent. Polar pesticides and 

their degradates, pharmaceutical compounds, and NDMA 

were not detected in any of the grid wells sampled in the Santa 

Barbara study unit. 

Eighteen grid wells were sampled for trace elements, 

major and minor ions, nutrients, and radioactive constituents; 

most detected concentrations were less than health-based 

benchmarks. Exceptions are one detection of boron 

greater than the CDPH notification level (NL-CA) of 

1,000 micrograms per liter (μg/L) and one detection of 

fluoride greater than the CDPH maximum contaminant level 

(MCL-CA) of 2 milligrams per liter (mg/L).

Results for constituents with non-regulatory benchmarks 

set for aesthetic concerns from the grid wells showed that iron 

concentrations greater than the CDPH secondary maximum 

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

in three grid wells. Manganese concentrations greater than 

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

Chloride was detected at a concentration greater than the 

SMCL-CA recommended benchmark of 250 mg/L in four 

grid wells. Sulfate concentrations greater than the SMCL-CA 

recommended benchmark of 250 mg/L were measured in eight 

grid wells, and the concentration in one of these wells was also 

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

TDS concentrations greater than the SMCL-CA recommended 

benchmark of 500 mg/L were measured in 17 grid wells, and 

concentrations in six of these wells were also greater than the 

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

Introduction 

About one-half of the water used for public and 

domestic drinking-water supply in California is groundwater 

(Kenny and others, 2009). To assess the quality of ambient 

groundwater in aquifers used for public drinking-water supply 

and to establish a baseline groundwater-quality monitoring 

program, the California State Water Resources Control Board 

(SWRCB), in cooperation with the U.S. Geological Survey 

(USGS) and Lawrence Livermore National Laboratory 

(LLNL), implemented the Groundwater Ambient Monitoring 

and Assessment (GAMA) Program (California Environmental 

Protection Agency, 2011, website at http://www.waterboards.

ca.gov/water_issues/programs/gama/). The main goals of 

the GAMA Program are to improve groundwater monitoring 

and to increase the availability of groundwater-quality data 

to the public. The GAMA Program currently consists of 

four projects: (1) the GAMA Priority Basin Project (PBP) 

conducted by the USGS (U.S. Geological Survey, 2011a, 

California Water Science Center website at http://ca.water.

usgs.gov/gama/); (2) the GAMA Domestic Well Project 

(DWP) conducted by the SWRCB; (3) the GAMA Special 

Studies conducted by LLNL; and (4) the GeoTracker GAMA 

online database conducted by the SWRCB. The GAMAPBP primarily focuses on the deep part of the groundwater 

resource, which is typically used for public drinking-water 

supply. The GAMA DWP generally focuses on the shallow 

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

of surficial contamination. The GAMA Special Studies 

Project focuses on using research methods to help explain 

the source, fate, transport, and occurrence of chemicals that 

can affect groundwater quality. GeoTracker GAMA is an 

online interface serving all published and quality-assurance/

quality-control (QA/QC) approved analytical data from the 

GAMA Program (California State Water Resources Control 

Board, 2009, website at http://geotracker.waterboards.ca.gov/

gama/). GeoTracker GAMA also stores groundwater-quality 

data and related reports collected by other State agencies, 

such as the California Department of Public Health (CDPH), 

California Department of Water Resources (CDWR), 

California Department of Pesticide Regulation (CDPR), and 

data collected by the SWRCB and Regional Boards from 

groundwater monitoring wells at contaminated or remediated 

sites.

The GAMA Program was initiated by the SWRCB 

in 2000 and later expanded by the Groundwater Quality 

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

Sections 10780–10782.3 of the California Water Code, 

Assembly Bill 599). The GAMA-PBP assesses groundwater 

quality in key groundwater basins that account for more 

than 90 percent of all groundwater used for public supply in 

the State. For the GAMA-PBP, the USGS, in collaboration 

with the SWRCB, developed the monitoring plan to assess 

groundwater basins through direct and other statistically 

reliable sample approaches (Belitz and others, 2003; 

California State Water Resources Control Board, 2003). 

Additional partners in the GAMA-PBP include LLNL, 

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

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

entirely voluntary.

The range of hydrologic, geologic, and climatic 

conditions in California should be considered in an 

assessment of groundwater quality. Belitz and others (2003) 

partitioned the State into 10 hydrogeologic provinces, 

each with distinctive hydrologic, geologic, and climatic 

characteristics: Cascades and Modoc Plateau, Klamath 

Mountains, Northern Coast Ranges, Central Valley, Sierra 

Nevada, Basin and Range, Southern Coast Ranges, Transverse 

Ranges and selected Peninsular Ranges, Desert, and San 

Diego Drainages (fig. 1). These 10 hydrogeologic provinces 

include groundwater basins and subbasins designated by the 

CDWR (California Department of Water Resources, 2003). 

Groundwater basins and subbasins generally consist of 

relatively permeable, unconsolidated deposits of alluvial or 
Introduction 3

volcanic origin. Eighty percent of California’s approximately 

16,000 active and standby drinking-water wells listed in the 

statewide database maintained by the CDPH (hereinafter 

referred to as CDPH wells) are located in groundwater 

basins and subbasins within the 10 hydrogeologic provinces. 

Groundwater basins and subbasins were prioritized for 

sampling on the basis of the number of CDPH wells in the 

basin, with secondary consideration given to municipal 

groundwater use, agricultural pumping, the number of 

formerly leaking underground fuel tanks, and the number of 

registered pesticide applications (Belitz and others, 2003). Of 

the 472 basins and subbasins designated by the CDWR, 116 

were identified as priority basins that include approximately 

95 percent of the CDPH wells in California. In addition, some 

areas outside of the defined groundwater basins were included 

to achieve representation of the 20 percent of the CDPH wells 

Figure 1. Hydrogeologic provinces of California and the location of the Santa Barbara study unit, California GAMA 

Priority Basin Project.

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

Santa Barbara

Study Unit

(figure 2)

Bakersfield

San

Francisco

Sacramento

OREGON

NEVADA

MEXICO

ARIZONA

Redding

Los Angeles

San Diego

PA C I F I C O C E A N

0 200 MILES

0 200 KILOMETERS

100

100

Shaded relief derived from U.S. Geological Survey

National Elevation Dataset, 2006, 

Albers Equal Area Conic Projection

Provinces from Belitz and others, 2003

IP-033483_Figure 01
4 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

not located in the groundwater basins. The priority basins, 

selected other basins, and selected areas outside of basins 

were grouped into 35 study units for sampling. The Santa 

Barbara study unit is composed of five groundwater subbasins 

in the Transverse Ranges and selected Peninsular Ranges 

hydrogeologic province (fig. 1).

Three types of water-quality assessments are being 

conducted with the data collected in each study unit: 

(1) Status—assessment of the current quality of the 

groundwater resource; (2) Understanding—identification of 

the natural and human factors affecting groundwater quality; 

and (3) Trends—detection of changes in groundwater quality 

over time (Kulongoski and Belitz, 2004). The assessments 

are intended to characterize the quality of groundwater in 

the primary aquifer system of the study units, not the treated 

drinking water delivered to consumers by water purveyors. 

The primary aquifer system is defined as parts of the aquifers 

corresponding to the perforation intervals of wells listed in the 

CDPH databases for the study units. The CDPH database lists 

wells used for public drinking-water supplies and includes 

wells from systems classified as community (such as those 

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

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

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

in campgrounds and parks). Collectively, the CDPH refers 

to these wells as “public-supply” wells. Groundwater quality 

in the primary aquifer system may differ from the quality in 

the shallow or deep parts of the aquifer systems. In particular, 

shallow groundwater may be more vulnerable to surface 

contamination. As a result, samples from shallow wells (such 

as many private domestic wells and environmental monitoring 

wells) can have higher concentrations of constituents (such 

as volatile organic compounds [VOCs] and nitrate) from 

anthropogenic sources than samples from wells screened in the 

underlying primary aquifer system (Landon and others, 2010).

The GAMA-PBP is unique in California because it 

includes many chemical analyses that are not otherwise 

available in statewide water-quality monitoring datasets. 

Groundwater samples collected for the GAMA-PBP 

are typically analyzed for approximately 300 chemical 

constituents by using methods with lower detection limits 

than required by the CDPH for regulatory monitoring of 

drinking-water wells. These analyses will be especially useful 

for providing an early indication of changes in groundwater 

quality. In addition, the GAMA-PBP analyzes samples for 

a suite of constituents more extensive than that required by 

CDPH and for a suite of chemical and isotope tracers for 

exploring hydrologic and geochemical processes. A broader 

understanding of groundwater composition is useful for 

identifying the natural and human factors affecting water 

quality. Understanding the occurrence and distribution of 

chemical constituents of significance to water quality is 

important for the long-term management and protection of 

groundwater resources.

This USGS Data Series Report is similar to other USGS 

Data Series Reports written for the GAMA-PBP study units 

sampled to date and is the first in a series of reports (i.e., 

Data Series Report, Scientific Investigations Report, and Fact 

Sheet) presenting the water-quality data collected in the Santa 

Barbara study unit. Data Series Reports and additional reports 

addressing the status, understanding, and trends aspects of 

the water-quality assessments of each study unit are available 

from the U.S. Geological Survey (2011b) at http://ca.water.

usgs.gov/gama/includes/GAMA_publications.html.

Purpose and Scope

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

hydrogeologic setting of the Santa Barbara study unit, the 

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

for groundwater samples collected in the Santa Barbara study 

unit, and (3) the results of quality-control (QC) analyses. 

Groundwater samples were analyzed for field water-quality 

indicators; organic, special-interest, inorganic, and radioactive 

constituents; naturally occurring isotopes; and dissolved gases. 

The chemical data presented in this report were evaluated by 

comparison to State and Federal drinking-water regulatory 

and other non-regulatory standards that are applied to treated 

drinking water. Regulatory and non-regulatory benchmarks 

considered for this report are those established by the 

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

CDPH. Discussion of the factors that influence the distribution 

and occurrence of the constituents detected in groundwater 

samples will be the subject of subsequent publications.

Hydrogeologic Setting 

The Santa Barbara study unit lies within the Transverse 

Ranges and selected Peninsular Ranges hydrogeologic 

province described by Belitz and others (2003). The study 

area covers 48 square miles (mi2

), primarily in Santa Barbara 

County, and extends into Ventura County to the east. The 

Santa Barbara study unit is a narrow coastal strip flanked by 

the Santa Ynez Mountains in the north with summit elevations 

over 4,000 feet (ft) and bounded by the Pacific Ocean in 

the south. The study unit includes five CDWR-defined 

groundwater basins and sub-basins: (from west to east) 

Goleta, Foothill, Santa Barbara, Montecito, and Carpinteria 

(California Department of Water Resources, 2003) (fig. 2A).
Hydrogeologic Setting 5 Figure 2. (A) Boundaries of California Department of Water Resources (CDWR) groundwater basins in the Santa Barbara study unit and the locations of counties, major cities, major roads, topographic features, and hydrologic features. (

B) Geologic map of the Santa Barbara Coastal Plain showing major faults and hydrologic features, Santa Barbara 

study unit, California GAMA Priority Basin Project.

GOLETA

CARPINTERIA

MONTECITO

SANTA

BARBARA

FOOTHILL

AB

Mission Creek

Santa Ynez RiverSanta Ynez River

Rincon Creek

Santa Monica Creek

Mission Creek

San Jose Creek

Carpinteria Creek

Gobernador Creek

Atascadero Creek

San Antonio Creek

Arroyo Paredon

San Roque Creek

Sycamore

Creek

Maria Ygnacio Creek

Franklin Creek

El Estero

GoletaSlough

Jameson Lake

LagunaBlanca

Santa Ynez Mountains

West Beach

Jameson Lake

Santa Ynez Mountains

West Beach

Mesa Fault

Arroyo Parida Fault

Modoc Fault

More Ranch Fault

El Encanto Fault

Rincon Creek Fault

Mission Ridge Fault Zone

Lavigia 

Fault 

154

101

SANTA

BARBARA

CO

VENTURA

CO

SANTA

BARBARA

CO

VENTURA

CO

Goleta

Montecito

Carpinteria

Santa Barbara

Shaded relief derived from U.S. Geological Survey National Elevation Dataset, 2006, Albers Equal Area Conic Projection

119°30’ 119°40’ 119°50’

34° 30’ 34°25’

IP033483_Figure 02ab

PACIFIC OCEAN

0 1 2 3 4 5 MILES0 1 2 3 4 5 KILOMETERS

119°30’ 119°40’ 119°50’

34° 30’ 34°25’

PACIFIC OCEAN EXPLANATION

Faults—Dashed where approximately located; dotted where concealed

Geologic unit (age)

Alluvial and surficial deposits (Holocene and upper Pleistocene)

Older alluvial deposits (Pleistocene), principally making up the water-bearing units

Sandstone and mudstone in the shallower unit, with conglomerates in the lower unit (Oligocene)

Metamorphic marine sediment (Mesozoic)

Marine-terrace deposits (upper Pleistocene)

Marine mudstone and shale (Miocene and some Pliocene)

Marine sediment (Eocene)

Study unitboundary
6 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

The Santa Barbara fold and fault belt (SBFFB) and 

the overlapping Santa Ynez Mountains uplift dominate the 

structural geology of the Santa Barbara coastal plain. The eastwest trending SBFFB is defined by three major fault systems: 

the west-northwest-trending Mission Ridge fault zone and 

Arroyo Parida fault, and the east-northeast-trending More 

Ranch fault (fig. 2B) (Minor and others, 2009). These systems 

and other individual faults define some subbasin boundaries 

as they impede water flow within and along the perimeter of 

the Santa Barbara study unit. Along the southern boundary 

of the study unit, seawater intrusion is partially restricted by 

uplift along the More Ranch fault in the southwest, Mesa 

and Lavigia faults in the central part of the coastal plain, and 

Rincon Creek fault in the southeast (California Department of 

Water Resources, 2004a–e). 

Deformed Eocene marine sediments along the southern 

flank of the Santa Ynez Mountains form the backdrop to 

the Santa Barbara coastal plain and give way to Oligocene 

through Pleistocene sedimentary rocks of the lower foothills 

(fig. 2B). Moderately warped Pleistocene marine and terrestrial 

sediments underlie many of the hills and mesas, with much 

of the low-lying, urbanized area underlain by Pleistocene and 

Holocene surficial deposits (Minor and others, 2009). The 

Santa Barbara study unit boundary encompasses water-bearing 

formations which are made up of these Quaternary deposits. 

The principal aquifer formations of the Santa Barbara 

study unit are the older alluvial deposits and the underlying 

Santa Barbara and Casitas Formations. Located in the western 

part of the Santa Barbara coastal plain, the middle and lower 

Pleistocene Santa Barbara Formation consists of fine- to 

medium-grained marine sandstone. In the central region of 

the study unit, the oldest alluvial deposits interstratify the 

Santa Barbara Formation below and may be correlative with 

the Casitas Formation. The consolidated nonmarine deposits 

of the Casitas Formation are of upper and middle Pleistocene 

age. The thickness varies from less than 164 ft found in 

outcrops to much thicker in the subsurface of Carpinteria, 

Montecito, and possibly Santa Barbara cities. The Casitas 

Formation is overlain with marine terrace deposits and was 

previously mapped as the Carpinteria Formation by Lian 

(1954). Alluvial deposits typically present in the upper part 

of marine terrace sequences may also be correlative with the 

intermediate and older alluvial deposits (Minor and others, 

2009). 

The sources of surface discharge for the study unit are 

several creeks flowing from the mountains out to the Pacific 

Ocean. The study unit is primarily drained by Mission Creek 

and its tributaries (fig. 2B). The creek originates in the Santa 

Ynez Mountains and flows southeasterly to where it enters 

the Pacific Ocean just east of West Beach (Izbicki and others, 

2009). Other surface-drainage features are San Jose, Maria 

Ygnacio, San Antonio, Atascadero, San Roque, Sycamore, 

Arroyo Paredon, Santa Monica, Rincon, Carpinteria, and 

Gobernador Creeks. Sources of recharge in the groundwater 

basins are infiltration of precipitation and irrigation waters, 

seepage from creeks and streams, imported water from Lake 

Cachuma and Gibraltar Reservoir, and subsurface inflow 

(California Department of Water Resources, 2004a–e).

The climate in the Santa Barbara study unit is 

characterized as Mediterranean, with warm, dry summers 

and cool, wet winters. The National Climatic Data Center 

located at the Santa Barbara Municipal Airport reported an 

average annual temperature of 58 degrees Fahrenheit (°F) 

(14.5 degrees Celsius [°C]) for 2010; total annual precipitation 

was higher than normal (about 17 inches) at more than 

27 inches, occurring as rain during the winter and early 

spring (U.S. Department of Commerce, National Oceanic and 

Atmospheric Administration, 2010).

Methods 

Methods used for the GAMA-PBP were selected to 

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

for suitable statistical representation; (2) collect samples in 

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

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

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

relevant documentation. The appendix contains detailed 

descriptions of the sample-collection protocols and analytical 

methods, the quality-assurance (QA) methods, and the results 

of analyses of QC samples.

Study Design

The wells selected for sampling in this study reflect the 

combination of two well-selection strategies. Eighteen wells 

were selected to provide a statistically unbiased, spatially 

distributed assessment of the quality of groundwater resources 

used for public drinking-water supply. Hereinafter, wells 

sampled as part of the spatially distributed, randomized 

grid-cell network are referred to as “grid wells.” Six 

additional, non-randomized wells (hereinafter referred 

to as “understanding wells”) were selected to aid in the 

understanding of specific issues associated with vertical 

changes in groundwater quality and age in different parts of 

the Santa Barbara study unit.

The grid wells were selected using a randomized gridbased method (Scott, 1990). The randomized grid-based 

method divides the study unit into equal-area grid cells; 

however, geographic features may force a grid cell to be 

divided into multiple pieces to obtain the designated coverage 

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

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

is still considered one grid cell. The Santa Barbara study unit 

was divided into 20 equal-area grid cells, each approximately 

2.4 mi2

 in area.
Methods 7

The objective was to sample one CDPH well in each grid 

cell (fig. 3A). If a grid cell contained more than one CDPH 

well, each well randomly was assigned a rank. The highest 

ranking well that met basic sampling criteria (for example, 

sampling point located prior to treatment or capability to 

pump for several hours) was sampled. If a grid cell contained 

no accessible CDPH wells, then other types of wells, such as 

irrigation wells, domestic wells, or commercial wells, were 

considered for sampling. These “alternative” wells were 

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

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

the six cells that contained no active wells, wells in adjacent 

cells near the cell boundaries were considered for sampling. 

In this fashion, 1 well was selected for sampling in 18 of the 

20 grid cells to provide a spatially distributed, randomized 

monitoring network. The remaining two cells contained no 

accessible wells. 

The 18 grid wells sampled in the Santa Barbara study unit 

were named by using the prefix “SB” and by using a suffix 

numbered by location within the study unit, from west to east 

(fig. 3B). The six understanding wells sampled as part of the 

study were not included in the statistical characterization of 

water quality in the Santa Barbara study unit because inclusion 

of these wells would have lead to the overrepresentation of 

some cells. These additional wells were named by using the 

prefix “SBU” (“U” indicating “understanding”) and by using 

a suffix numbered from west to east within the study unit. Of 

the understanding wells, four were short-screened monitoring 

(observation) wells at a single location with openings at 

different depths in the aquifer system. 

The GAMA alphanumeric identification number for each 

well, along with the date sampled, well altitude, well type, 

and available well-construction information are shown in

table 1. Groundwater samples were collected during January 

and February 2011. Grid wells included 11 CDPH wells, 5 

irrigation wells, and 2 domestic wells. Understanding wells 

included four monitoring (observation) wells, one publicsupply well, and one unused well. 

Well locations were verified by using a global positioning 

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

comparison with existing well information in USGS and 

CDPH databases, and information provided by well owners, 

drillers’ logs, or other sources of construction information. 

Well locations and information were recorded by hand on field 

sheets and electronically on field laptop computers using the 

Alternate Place Entry (APE) program designed by the USGS. 

All information was verified and then uploaded into the USGS 

National Water Information System (NWIS). Well owner, well 

use, and well location information is confidential.

Sample Collection and Analysis

Samples were collected in accordance with the protocols 

established by the USGS National Water-Quality Assessment 

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

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

variously dated). These sampling protocols were followed so 

that representative samples of groundwater were collected at 

each site and so that the samples were collected and handled in 

ways that minimized the potential for contamination.

All 24 wells in the Santa Barbara study unit were 

sampled for a standard set of constituents (table 2). 

Tables 3A–K list the compounds analyzed in each 

constituent class. Groundwater samples were analyzed for 

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

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

13 pharmaceutical compounds (table 3D); 2 constituents of 

special interest (table 3E); 24 trace elements (table 3F); 5 

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

dissolved solids (table 3H); arsenic, chromium, and iron 

species (table 3I); stable isotopes of hydrogen and oxygen 

in water, dissolved inorganic carbon, and dissolved boron, 

and isotope ratios of dissolved strontium, and 5 radioactive 

constituents, including tritium and carbon-14 abundance 

(table 3J); stable isotope ratios of helium, 5 dissolved noble 

gases, and tritium (table 3K). The methods used for sample 

collection and analysis are described in the appendix section 

titled “Sample Collection and Analysis.”

Data Reporting

The methods and conventions used for reporting the data 

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

Six constituents analyzed in this study were measured by 

more than one method at the USGS National Water Quality 

Laboratory (NWQL), four of which only have results reported 

from the preferred method (see the appendix section titled 

“Constituents on Multiple Analytical Schedules” for the 

preferred method selection procedure). Three field waterquality indicators—alkalinity, pH, and specific conductance 

(table 4)—were measured in the field and at the NWQL, 

and three other constituents—total arsenic, chromium, and 

iron—were measured by two different laboratories; both sets 

of results are reported for each of these constituents. Tritium 

activities were measured by two different laboratories, but 

only one set of results was available at the time this report was 

published.
8 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Figure 3. (A) The distribution of the grid cells and the location of public-supply wells from the California Department of Public Health (CDPH) database, and (B) the distribution 

of grid cells, the location of sampled grid and understanding wells, Santa Barbara study unit, California GAMA Priority Basin Project.

AB

Mission Creek

Santa Ynez RiverSanta Ynez River

Mission Creek

El Estero

GoletaSlough

Jameson Lake

LagunaBlanca

Santa Ynez Mountains

West Beach

Jameson Lake

Santa Ynez Mountains

West Beach

154

101

154

101

SANTA

BARBARA

CO

VENTURA

CO

SANTA

BARBARA

CO

VENTURA

CO

Shaded relief derived from U.S. Geological Survey National Elevation Dataset, 2006, Albers Equal Area Conic Projection

119°30’ 119°40’ 119°50’

34° 30’ 34°25’

IP033483_Figure 03ab

PACIFIC OCEAN

0 1 2 3 4 5 MILES0 1 2 3 4 5 KILOMETERS

119°30’ 119°40’ 119°50’

34° 30’ 34°25’

PACIFIC OCEAN

Public-supply well (with a record in CDPH)

EXPLANATION

EXPLANATION

Grid wellUnderstanding well

SB-18

SB-17

SB-16 SB-15

SB-14

SB-13

SB-12

SB-11

SB-09

SB-10

SB-08

SB-07

SB-06

SB-05

SB-04

SB-03

SB-02

SB-01 SBU-06

SBU-02SBU-03SBU-04SBU-05

SBU-01
Water-Quality Results 9

Quality-Assurance Methods

The QA procedures used for this study followed the 

protocols used by the NAWQA Program (Koterba and 

others, 1995) and described in the NFM (U.S. Geological 

Survey, variously dated). The QA plan followed by the 

NWQL, the primary laboratory used to analyze samples 

for this study, is described in Pirkey and Glodt (1998) and 

Maloney (2005). QC samples collected in the Santa Barbara 

study unit are blanks, replicates, and matrix and surrogate 

spikes. QC samples were collected to evaluate potential 

contamination, as well as bias and variability of the data that 

may have resulted from sample collection, processing, storage, 

transportation, and laboratory analysis. QA procedures 

and QC results are described in the appendix section titled 

“Quality-Assurance Methods and Results.”

Water-Quality Results 

Quality-Control Results

Results of QC analyses (blanks, replicates, and matrix 

and surrogate spikes) were used to evaluate the quality of the 

data for the groundwater samples. On the basis of detections 

in field blanks collected for this and previous GAMAPBP study units, raised “study reporting levels” (SRLs) 

for 1 volatile organic compound (1,2,4-trimethylbenzene), 

11 trace elements, and 1 nutrient (ammonia) were applied (see 

table A3 and additional discussion in the appendix section 

titled “Detections in Field Blanks and Application of SRLs”). 

Detections of these 13 constituents with concentrations less 

than their SRLs were flagged with a less than or equal to 

symbol (≤) in this report and in the NWIS database (tables 5, 

8, and 9).

Results from the replicate analyses confirm that the 

procedures used to collect and analyze the samples were 

consistent. Variability for nearly 100 percent of the replicate 

pairs for constituents detected in samples was within the 

acceptable limits (tables A4A–C). The criteria for acceptable 

replication is described in the appendix section titled “Quality 

Assurance Methods and Results.” Median matrix-spike 

recoveries for 31 of the 205 organic constituents analyzed 

were lower than the acceptable limit of 70 percent, and 6 were 

greater than the acceptable limit of 130 percent (tables 3A–D 

and A5A–D). The constituents for which low recoveries 

occurred might not have been detected in some samples if 

they were present in the samples at concentrations near the 

laboratory reporting levels (LRLs). Constituents with high 

recoveries may indicate that reported values could be greater 

than what is in the sample. The QC results are described in 

the appendix section titled “Quality-Control Methods and 

Results.”

Comparative Benchmarks

Concentrations of constituents detected in groundwater 

samples were compared with CDPH and USEPA regulatory 

and non-regulatory drinking-water health-based benchmarks 

and benchmarks established for aesthetic purposes (California 

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

Protection Agency, 2008a−c). The chemical data presented 

in this report are meant to characterize the quality of the 

untreated groundwater within the primary aquifer system of 

the Santa Barbara study unit and are not intended to represent 

the treated drinking water delivered to consumers by water 

purveyors. The chemical composition of treated drinking 

water may differ from untreated groundwater because treated 

drinking water may be subjected to disinfection, filtration, 

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

prior to its delivery to consumers. Comparisons of untreated 

groundwater to benchmarks are for illustrative purposes only 

and are not indicative of compliance or non-compliance with 

drinking-water regulations. The following benchmarks were 

used for comparisons:

• MCL–Maximum Contaminant Level. Legally 

enforceable standards that apply to public-water 

systems and are designed to protect public health by 

limiting the levels of contaminants in drinking water. 

MCLs established by the USEPA are the minimum 

standards with which States are required to comply, 

and individual States may choose to set more stringent 

standards. CDPH has established MCLs for additional 

constituents not regulated by the USEPA, as well as 

lowered the benchmark concentrations for a number 

of constituents with MCLs established by the USEPA. 

In this report, a benchmark 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.” Well owners are notified when 

constituents are detected at concentrations greater than 

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

collected for the GAMA-PBP, but these detections do 

not constitute violations of CDPH regulations.

• AL–Action Level. Legally enforceable standards that 

apply to public-water systems and are designed to 

protect public health by limiting the levels of copper 

and lead in drinking water. Detections of copper or 

lead greater than the action-level benchmarks trigger 

requirements for mandatory water treatment to reduce 

the corrosiveness of water to water pipes. The action 

levels established by the USEPA and CDPH are the 

same; thus, these benchmarks are labeled “AL-US” in 

this report.
10 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

• SMCL–Secondary Maximum Contaminant Level. 

Non-enforceable standards applied to constituents that 

affect the aesthetic qualities of drinking water, such 

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

drinking water, such as scaling and staining. Both the 

USEPA and CDPH define SMCLs, but unlike MCLs, 

SMCLs established by CDPH are not required to be 

at least as stringent as those established by USEPA. 

SMCLs established by CDPH are used in this report 

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

values. The SMCL-US is used for pH because no 

SMCL-CA has been defined.

• NL–Notification Level. Health-based notification 

levels established by CDPH for some of the 

constituents in drinking water that lack MCLs (NLCA). If a constituent is detected in drinking water at 

concentrations greater than its NL-CA, California State 

law requires timely notification of local governing 

bodies and recommends consumer notification.

• HAL–Lifetime Health Advisory Level. The 

maximum concentration of a constituent at which its 

presence in drinking water is not expected to cause any 

adverse carcinogenic effects for a lifetime of exposure. 

HALs are established by the USEPA (HAL-US) 

and are calculated assuming consumption of 2 liters 

(2.1 quarts) of water per day over a 70-year lifetime by 

a 70-kilogram (154-pound) adult and that 20 percent of 

a person’s exposure comes from drinking water.

• RSD5–Risk-Specific Dose. The concentration of 

a constituent in drinking water corresponding to 

an excess estimated lifetime cancer risk of 1 in 

100,000. RSD5 is an acronym for risk-specific 

dose at the 10–5 risk level (10–5 equals 1/100,000). 

RSD5s are calculated by dividing the 10–4 cancer 

risk concentration established by the USEPA by 10 

(RSD5-US).

For constituents with regulatory benchmarks (MCLs or 

ALs), detections in groundwater samples were compared to 

the MCL-US, MCL-CA, or AL-US. 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; detections of 

these constituents in groundwater samples were compared 

with both levels. The SMCL-US levels for these constituents 

correspond to their recommended SMCL-CAs. Detected 

concentrations of constituents without an MCL, AL, or SMCL 

were compared to the NL-CA. For constituents without 

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

were compared with the HAL-US. For constituents without 

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

concentrations were compared with the RSD5-US. Note that 

using this hierarchy to select the comparative benchmark for a 

constituent with more than one type of established benchmark 

will not necessarily result in selection of the benchmark with 

the lowest concentration. For example, for zinc the SMCL-CA 

is 5,000 micrograms per liter (μg/L) and the HAL-US is 

2,000 μg/L, but the comparative benchmark selected by this 

hierarchy is the SMCL-CA. The comparative benchmarks 

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

and in tables 4–13 for constituents detected in groundwater 

samples from the Santa Barbara study unit. Established 

benchmarks are not available for all constituents analyzed for 

this study. Detections of constituents at concentrations greater 

than the selected comparative benchmarks are marked with an 

asterisk (*) in tables 4, 8, 10, and 11. 

Groundwater-Quality Data

Results from analyses of untreated groundwater samples 

from the Santa Barbara study unit are presented in tables 4–13. 

Groundwater samples collected in the Santa Barbara study unit 

were analyzed for 281 constituents. Of those constituents, 207 

were not detected in any of the samples, and 66 constituents 

were detected. The results for stable isotopes of dissolved 

boron, isotope ratios of dissolved strontium, and the LLNL 

results for dissolved noble gases, tritium, and helium isotope 

ratios have not been received and are not presented in this 

report; they will be included in a subsequent publication. 

For organic and special-interest constituents, the results 

tables include only those constituents that were detected, and 

the following summary statistics are presented for all of the 

grid wells: the number of wells at which each analyte was 

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

to the number of grid wells in the study unit), and the total 

number of constituents detected at each well (except for 

special-interest constituents because only one constituent 

was analyzed). For the inorganic, isotopic, and radioactive 

constituents, the tables include all of the constituents and wells 

that were analyzed. 

Water-quality indicators measured in the field and at the 

NWQL are included in table 4. The results of groundwater 

analyses, organized by constituent class, are presented in 

tables 5–13: 

• Organic constituents

• Volatile organic compounds (table 5)

• Pesticides and pesticide degradates (table 6)

• Perchlorate (table 7)

• Inorganic constituents

• Trace elements (table 8)

• Nutrients (table 9)

• Major and minor ions, silica, and total dissolved 

solids (table 10)

• Arsenic, chromium, and iron species (table 11)
Water-Quality Results 11

• Isotope tracers (table 12)

• Radioactive constituents 

• Radon-222 (table 13A)

• Gross alpha and gross beta radioactivity (table 13B)

Water-Quality Indicators 

Field measurements of dissolved oxygen and water 

temperature and field and laboratory measurements of pH, 

specific conductance, and alkalinity are presented in table 4. 

Bicarbonate and carbonate concentrations were calculated 

from the pH and alkalinity results. Dissolved oxygen and 

alkalinity are used as indicators of natural processes that affect 

water chemistry. The pH value indicates the acidity or basicity 

of the water. Specific conductance is the measure of electrical 

conductivity of the water and is proportional to the amount of 

total dissolved solids (TDS) in the water. 

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

17 percent of the Santa Barbara study unit grid wells: three 

well samples had field pH values less than 6.5 (table 4). Low 

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

in water may contribute to scaling. Laboratory pH values may 

differ from field pH values because the pH of groundwater 

may change upon removal from the ambient environment and 

exposure to the atmosphere.

Field specific-conductance values were greater than the 

recommended SMCL-CA of 900 microsiemens per centimeter 

at 25 degrees Celsius (μS/cm at 25°C) for 15 of the 18 gridwell samples, 5 of which were also greater than the upper 

benchmark of 1,600 μS/cm at 25°C. Five Santa Barbara 

understanding-well samples had field specific-conductance 

values that were greater than the recommended SMCL-CA, 

one of which was also greater than the upper SMCL-CA 

(table 4). 

Organic Constituents

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

refrigerants, fumigants, and disinfected water, and are 

characterized by their tendency to evaporate. VOCs generally 

persist longer in groundwater than in surface water because 

groundwater is isolated from the atmosphere. 

Of the 85 VOCs analyzed for the Santa Barbara study 

unit, 11 were detected in groundwater samples; 9 of these 

11 VOCs were detected in grid wells. All concentrations 

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

more VOCs were detected in 11 of the 18 grid-well samples 

(about 61 percent detection frequency). The trihalomethane 

chloroform was the most frequently detected VOC in 

the study unit. Chloroform is among the most commonly 

detected VOCs in groundwater nationally, and its source 

is attributed, in part, to the recycling of chlorinated waters 

to aquifers (Zogorski and others, 2006). Five other VOCs 

also had detection frequencies greater than 10 percent in the 

grid wells: bromodichloromethane; 1,1,1-trichloroethane; 

1,1-dichloroethane; perchloroethene (PCE, tetrachloroethene); 

and the gasoline oxygenate, methyl tert-butyl ether (MTBE). 

Four VOCs were detected in one of the understanding-well 

samples in the Santa Barbara study unit (SBU-05).

Pesticides include herbicides, insecticides, and fungicides 

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

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

120 pesticides and pesticide degradates analyzed at 18 grid 

wells in the Santa Barbara study unit, one was detected in 

groundwater samples: simazine. All concentrations were 

less than health-based benchmarks (table 6). No pesticide 

or pesticide degradate was detected in any of the six 

understanding wells. 

Pharmaceutical compounds may enter the environment 

in many ways, including septic systems, discharge of 

treated wastewater, sewer lines, seepage from landfills, land 

application of manure fertilizers, and runoff from animal 

wastes (Fram and Belitz, 2011). Pharmaceutical compounds 

were not detected at concentrations greater than or equal to 

the method detection limits (MDLs) in any of the 24 wells 

sampled for the Santa Barbara study unit.

Constituents of Special Interest

Perchlorate and NDMA are constituents of special 

interest in California because they may adversely affect 

water quality and recently have been detected in water 

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

Perchlorate was detected in 12 of 18 grid-well samples (about 

67 percent detection frequency) and in 2 of the understandingwell samples (table 7). Perchlorate was not detected at 

concentrations greater than the MCL-CA of 6 μg/L in any of 

the grid- or understanding-well samples in the Santa Barbara 

study unit. NDMA was not detected in any of the grid or 

understanding wells and therefore was not included in table 7.

Inorganic Constituents

Unlike the organic constituents and the constituents 

of special interest, most of the inorganic constituents 

generally are naturally present in groundwater, although their 

concentrations may be influenced by human activities. 

Seventeen of the 24 trace elements and 1 of the major 

and minor ions analyzed and detected in the Santa Barbara 

study unit have regulatory or non-regulatory health-based 

benchmarks (tables 3F, 3H). Of these 18 constituents with 

health-based benchmarks, 4 constituents were detected at 

concentrations greater than benchmarks; all detections of 

14 constituents had concentrations less than their respective 

benchmarks. One grid-well sample (SB-14) contained boron 

and fluoride at concentrations greater than benchmark levels: 

CDPH notification level (NL-CA) of 1,000 μg/L and MCL-CA 
12 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

of 2 milligrams per liter (mg/L), respectively (tables 8 and 

10). One understanding-well sample had detections of barium, 

boron, and strontium greater than the benchmark levels: 

MCL-CA of 1,000 μg/L, NL-CA of 1,000 μg/L, and HAL-US 

of 4,000 μg/L, respectively.

Nutrients (nitrogen and phosphorus) present in 

groundwater can affect biological activity in aquifers and 

in surface-water bodies that receive groundwater discharge. 

Inorganic nitrogen may be present in the form of ammonia, 

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

the groundwater. High concentrations of nitrate can adversely 

affect human health, particularly the health of infants. All 

concentrations of ammonia, nitrite, and nitrate measured in the 

24 Santa Barbara study unit wells were less than health-based

benchmarks (table 9). 

The levels of certain trace elements, major-ion 

composition, and TDS content in groundwater affect the 

aesthetic properties of water, such as taste, color, and odor, 

and the technical properties of water, such as scaling and 

staining. Although there are no adverse health effects directly 

associated with these properties, they may reduce consumer 

satisfaction with the water or may have economic effects. 

The CDPH has established non-enforceable benchmarks 

(SMCL-CAs) that are based on aesthetic properties rather 

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

zinc, chloride, sulfate, and TDS. Iron and manganese are trace 

elements whose concentrations are affected by the oxidationreduction state of the groundwater. Precipitation of minerals 

containing iron or manganese may cause orange, brown, or 

black staining of surfaces. 

Iron concentrations greater than the SMCL-CA of 

300 μg/L were detected in three grid-well samples. Manganese 

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

detected in seven grid-well samples. Iron was detected at 

a concentration greater than the benchmark level in one 

understanding-well sample, and manganese was detected 

at concentrations greater than the benchmark level in three 

understanding-well samples (table 8). 

Chloride concentrations were greater than the 

recommended SMCL-CA of 250 mg/L in four grid-well 

samples. Chloride was detected at a concentration greater 

than the upper SMCL-CA of 500 mg/L in one understandingwell sample. Sulfate concentrations were greater than the 

recommended SMCL-CA of 250 mg/L in eight grid-well 

samples, one of which was also above the upper SMCL-CA of 

500 mg/L. Sulfate was detected at a concentration greater than 

the recommended SMCL-CA in one understanding well. TDS 

concentrations were greater than the recommended SMCL-CA 

of 500 mg/L for 17 grid-well samples, 6 of which were 

also greater than the upper SMCL-CA of 1,000 mg/L. TDS 

concentrations were greater than the recommended SMCL-CA 

for five of the six understanding-well samples, one of which 

was also greater than the upper SMCL-CA (table 10). 

Arsenic, chromium, and iron occur as different species 

depending on the oxidation-reduction state of the groundwater. 

The oxidized and reduced species have different solubilities in 

groundwater and may have different effects on human health. 

The relative proportions of the oxidized and reduced species 

of each element can be used to aid in interpretation of the 

oxidation–reduction conditions of the aquifer, which affect the 

mobility of many constituents. Concentrations of total arsenic, 

chromium, and iron and the dissolved concentration of either 

the reduced or the oxidized species of these elements are 

reported in table 11. 

Isotopic Tracers

The isotopic delta values, activities, and abundances 

of many elements and the concentrations of dissolved gases 

(including noble gases) may be used as tracers of hydrologic 

processes (Clark and Fritz, 1997). 

Stable isotopes of hydrogen and oxygen in water 

(table 12) aid in the interpretation of the sources of 

groundwater recharge (see appendix section titled “Notation” 

for how the isotope delta values are calculated). These 

stable-isotope delta values reflect the altitude, latitude, and 

temperature of precipitation and also the extent of evaporation 

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

into the aquifer. 

Tritium activities (table 12) and helium isotope ratios 

provide information about the age (time since recharge) of 

groundwater. Tritium is a short-lived radioactive isotope of 

hydrogen that is incorporated into the water molecule. Low 

levels of tritium are produced continuously by interaction 

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

amount of tritium was produced as a result of atmospheric 

testing of nuclear weapons between 1952 and 1963. Thus, 

concentrations of tritium greater than background generally 

indicate the presence of water recharged after the early 1950s. 

Helium isotope ratios are used in conjunction with tritium 

concentrations to estimate ages for young groundwater. Of 

the isotope-tracer constituents analyzed for this study, tritium 

is the only one with a health-based benchmark. All measured 

tritium activities in samples from the Santa Barbara study unit 

were less than 1/1,000 of the MCL-CA benchmark (table 12). 

Carbon-14 (table 12), a radioactive isotope of carbon, 

is also an age-dating tracer. Low levels of carbon-14 are 

produced continuously by interaction of cosmic radiation with 

the Earth’s atmosphere and incorporated into atmospheric 

carbon dioxide. Carbon dioxide dissolves in precipitation, 

surface water, and groundwater exposed to the atmosphere, 

thereby entering the hydrologic cycle. Because carbon-14 

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

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

indicate a presence of groundwater that is several thousand 

years old or more. 
Summary 13

Radioactive Constituents

Radioactivity is the release of energy or energetic 

particles during changes in the structure of the nucleus of an 

atom. Most radioactivity in groundwater comes from decay 

of naturally occurring isotopes of uranium and thorium that 

are present in minerals in the sediments or fractured rocks of 

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

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

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

radioactive element turns into a different radioactive element 

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

alpha and beta particles emitted during radioactive decay may 

be hazardous to human health because these energetic particles 

may damage cells. Radiation damage to cell DNA may 

increase the risk of getting cancer.

Activity often is used instead of concentration for 

reporting the presence of radioactive constituents. Activity of 

radioactive constituents in groundwater is measured in units 

of picocuries per liter (pCi/L), and 1 pCi/L is approximately 

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

decaying is equal to the number of alpha or beta particles 

emitted. 

Radon-222 was sampled for at 22 of the 24 wells in 

the Santa Barbara study unit. Radon-222 activity was less 

than the proposed MCL-US of 4,000 pCi/L in all sampled 

wells (table 13A). The proposed MCL-US will apply if the 

state or local water agency has an approved multimedia 

mitigation program to address radon levels in indoor air 

(U.S. Environmental Protection Agency, 1999). Activities in 

all grid- and understanding-well samples for gross alpha and 

gross beta radioactivity were less than established healthbased benchmarks (table 13B). 

Future Work

Subsequent reports for the Santa Barbara study unit will 

be focused on assessment of the data presented in this report 

by using a variety of statistical, qualitative, and quantitative 

approaches to evaluate the natural and human factors 

affecting groundwater quality in the Santa Barbara study unit. 

Water-quality data contained in the CDPH databases will be 

compiled, evaluated, and used in combination with the data 

that are presented in this report. Additionally, these subsequent 

reports will include the results for the analysis of stable 

isotopes of dissolved boron and strontium in water and the 

LLNL results (dissolved noble gas, tritium, and helium isotope 

ratios) for the Santa Barbara study unit.

Summary 

Groundwater quality in the 48-square-mile Santa 

Barbara study unit was investigated by the U.S. Geological 

Survey (USGS) from January to February 2011, as part of the 

California State Water Resources Control Board (SWRCB) 

Groundwater Ambient Monitoring and Assessment (GAMA) 

Program’s Priority Basin Project (PBP). The GAMA 

Program was created to provide a comprehensive baseline 

of groundwater quality in the State. The GAMA-PBP was 

created as a result of the Groundwater Quality Monitoring 

Act of 2001 (Sections 10780–10782.3 of the California Water 

Code, Assembly Bill 599) to assess and monitor the quality 

of groundwater. The GAMA-PBP is being conducted by 

the USGS in cooperation with the SWRCB and Lawrence 

Livermore National Laboratory (LLNL).

The GAMA Santa Barbara study was designed to provide 

a spatially unbiased assessment of untreated-groundwater 

quality within the primary aquifer system and to facilitate 

statistically consistent comparisons of untreated-groundwater 

quality throughout California. The primary aquifer system 

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

California Department of Public Health (CDPH) database for 

the Santa Barbara study unit. The quality of groundwater in 

shallow or deeper water-bearing zones may differ from that in 

the primary aquifer system; shallow groundwater may be more 

vulnerable to surficial contamination.

This study did not attempt to evaluate the quality of 

water delivered to consumers; after withdrawal from the 

ground, water typically is treated, disinfected, and blended 

with other waters to maintain acceptable water quality. 

Regulatory benchmarks apply to treated water that is served 

to the consumer, not to untreated groundwater. However, 

to provide some context for the results, concentrations of 

constituents measured in the untreated groundwater were 

compared with regulatory and non-regulatory health-based 

benchmarks established by the U.S. Environmental Protection 

Agency (USEPA) and CDPH and non-regulatory benchmarks 

established for aesthetic concerns by the CDPH.

The Santa Barbara study unit is located within the 

Transverse and selected Peninsular Ranges hydrologic 

province and includes five groundwater basins defined by 

the California Department of Water Resources. The Santa 

Barbara study included assessment of the groundwater quality 

from 24 wells in Santa Barbara County. Eighteen wells were 

selected by using a randomized grid approach to achieve a 

statistically unbiased representation of groundwater used for 

public drinking-water supplies (grid wells), and six additional 

wells were selected to aid in the evaluation of water-quality 

issues (understanding wells). 
14 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

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

constituents, inorganic constituents, and radioactive 

constituents. Naturally occurring isotopes and dissolved noble 

gases also were measured to provide a dataset that will be used 

to interpret the sources and ages of the sampled groundwater. 

In total, 281 constituents and water-quality indicators were 

measured for this study. This report describes the sampling, 

analytical, and quality-assurance methods used in the study, 

and presents the results of the chemical analyses of the 

groundwater samples.

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

and matrix spikes) were collected at up to 12 percent of 

the wells in the Santa Barbara study unit, and the results 

for these samples were used to evaluate the quality of the 

data for the groundwater samples. Blanks rarely contained 

detectable concentrations of any constituent, suggesting that 

contamination from sample collection procedures was not 

a significant source of bias in the data for the groundwater 

samples. Replicate samples generally were within the limits of 

acceptable analytical reproducibility. Matrix-spike recoveries 

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

approximately 87 percent of the compounds.

All constituents were sampled for at all 24 wells in 

the Santa Barbara study unit, and most detections had 

concentrations less than drinking-water benchmarks. 

In the grid-well samples, one detection of boron was 

greater than the CDPH notification level (NL-CA), and one 

detection of fluoride was greater than the CDPH maximum 

contaminant level (MCL-CA). The following constituents had 

concentrations in grid-well samples greater than their CDPH 

secondary maximum contaminant levels (SMCL-CA): 3 

detections of iron, 7 detections of manganese, 4 detections of 

chloride, 8 detections of sulfate (1 of which was also greater 

than the SMCL-CA upper benchmark), and 17 detections of

TDS (6 of which were also greater than the SMCL-CA upper 

benchmark).

In the understanding-well samples, one detection of 

barium was greater than the MCL-CA, one detection of boron 

was greater than the NL-CA, and one detection of strontium 

was greater than the USEPA lifetime health advisory level 

(HAL-US). Three detections of manganese were greater than 

the SMCL-CA. One detection of chloride was greater than the 

recommended and upper SMCL-CA, one detection of sulfate 

was greater than the SMCL-CA, and five detections of TDS 

were greater than the recommended SMCL-CA (one detection 

was also greater than the upper SMCL-CA). 

Acknowledgments

The authors thank the following cooperators for their 

support: the California State Water Resources Control 

Board, California Department of Public Health, California 

Department of Water Resources, and Lawrence Livermore 

National Laboratory. We especially thank the well owners and 

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

collect samples from their wells.

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20 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Table 1. Identification, sampling, and construction information for wells sampled for the Santa Barbara study unit, January to 

February 2011, California GAMA Priority Basin Project.

[GAMA well identification number: SB, Santa Barbara study unit grid well; SBU, Santa Barbara study unit understanding well. Other abbreviations: ft, foot; 

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

GAMA well 

identification 

number

Date Sampled 

(m/dd/ yyyy)

Altitude of LSD 

(ft above NAVD 88)1 Well type

Construction information

Well depth 

(ft below LSD)

Depth to top 

perforation 

(ft below LSD)

Depth to bottom 

perforation 

(ft below LSD)

Santa Barbara grid wells

SB-01 2/3/2011 47 Production 150 110 150

SB-02 2/1/2011 21 Production 840 210 820

SB-03 2/1/2011 108 Production 450 250 450

SB-04 1/31/2011 45 Production 700 180 680

SB-05 2/14/2011 363 Production 420 255 410

SB-06 2/2/2011 83 Production 630 350 630

SB-07 1/26/2011 191 Production 427 215 427

SB-08 1/26/2011 177 Production 588 203 583

SB-09 2/8/2011 545 Production 350 140 350

SB-10 2/8/2011 30 Production 145 55 145

SB-11 2/9/2011 26 Production 206 100 206

SB-12 2/7/2011 267 Production 140 na na

SB-13 2/7/2011 81 Production 460 170 460

SB-14 2/9/2011 358 Production 975 195 975

SB-15 2/2/2011 43 Production 958 317 938

SB-16 2/3/2011 66 Production 1,245 310 1,230

SB-17 2/16/2011 153 Production 250 na na

SB-18 2/10/2011 198 Production 295 85 295

Santa Barbara understanding wells

SBU-01 1/31/2011 46 Production 1,110 549 1,065

SBU-02 1/24/2011 35 Monitoring 780 760 780

SBU-03 1/24/2011 35 Monitoring 670 650 670

SBU-04 1/25/2011 35 Monitoring 441 420 440

SBU-05 1/25/2011 35 Monitoring 221 200 220

SBU-06 2/15/2011 22 Unused 464 280 464

1

 LSD is a datum plane that is approximately at land surface at each well. The altitude of the LSD is described in feet above the North American Vertical 

Datum of 1988.

Tables
Tables 21

Table 2. Classes of chemical constituents and field water-quality indicators collected for the Santa Barbara study unit, January to 

February 2011, California GAMA Priority Basin Project.

Constituent classes Constituent 

list table

Results 

table

Field water-quality indicators 

Dissolved oxygen, temperature, pH, and specific conductance — 4

Field alkalinity, bicarbonate, and carbonate — 4

Organic constituents

Volatile organic compounds (VOC) 3A 5

Pesticides and pesticide degradates 3B 6

Polar pesticides and degradates 3C none 1

Pharmaceutical compounds 3D none 1

Constituents of special interest

Perchlorate 3E 7

N-Nitrosodimethylamine (NDMA) 3E none 1

Inorganic constituents

Trace elements 3F 8

Nutrients 3G 9

Major and minor ions, silica, and total dissolved solids (TDS) 3H 10

Laboratory alkalinity, bicarbonate, and carbonate 3H 4

Arsenic, chromium, and iron species 3I 11

Isotopic tracers, dissolved noble gases, and radioactive constituents

Stable isotopes of hydrogen and oxygen in water 3J 12

Stable isotopes of carbon in dissolved inorganic carbon and carbon-14 abundance 3J 12

Stable isotopes of dissolved boron in water 3J none 2

Isotope ratio of dissolved strontium in water 3J none 2

Tritium 3J 12

Stable isotope ratio of helium, dissolved nobles gases, and tritium 3K none 2

Radon-222 3J 13A

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

1

 Constituent(s) not detected in groundwater samples. 

2

 Results were not completed in time for inclusion in this report; results will be presented in a subsequent publication.
22 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program Table 3A.

Volatile organic compounds (VOCs), primary uses or sources, comparative benchmarks, and reporting information for the USGS National Water Quality Laboratory 

Schedule 2020.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Laboratory reporting level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant level; NL-CA, CDPH notification level; RSD5-US, USEPA risk-specific dose at a risk factor of 10–5. Other abbreviations: USGS, U.S. Geological Survey; 

CAS, Chemical Abstract Service; LRL, laboratory reporting level; SRL, study reporting level; THM, trihalomethane; D, detected in groundwater samples (table 5); na, not available; μg/L, micrograms per liter; —, not detected]

Constituent 

(synonym or abbreviation)

Primary use 

or source

USGS 

parameter 

code

CAS 

Registry Number® 1

 LRL 

(μg/L)

Benchmark 

type

Benchmark 

level

(μg/L)

Detection

Acetone Solvent 81552 67-64-1 3.4 na na

—

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

—

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

—

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

Bromobenzene Solvent 81555 108-86-1 0.022 HAL-US 70

—

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

—

Bromodichloromethane Disinfection byproduct (THM) 32101 75-27-4 0.034 MCL-US 2 80

D

Bromoform (Tribromomethane) Disinfection byproduct (THM) 32104 75-25-2 0.1 MCL-US 2 80

—

Bromomethane (Methyl bromide) Fumigant 34413 74-83-9 0.20 HAL-US 10

—

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

—

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

—

tert-Butylbenzene Gasoline hydrocarbon 77353 98-06-6 0.060 NL-CA 260

—

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

—

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

D

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

—

Chloroethane Solvent 34311 75-00-3 0.06 na na

—

Chloroform (Trichloromethane) Disinfection byproduct (THM) 32106 67-66-3 0.03 MCL-US 2 80

D

Chloromethane Solvent 34418 74-87-3 0.14 na na

—

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

—

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

—

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

—

Dibromochloromethane Disinfection byproduct (THM) 32105 124-48-1 0.12 MCL-US 2 80

—

1,2-Dibromo-3-chloropropane (DBCP) Fumigant 82625 96-12-8 0.40 MCL-US 0.2

—

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

—

Dibromomethane Solvent 30217 74-95-3 0.050 na na

D

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

—

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

—
Tables 23

Constituent 

(synonym or abbreviation)

Primary use 

or source

USGS 

parameter 

code

CAS 

Registry Number® 1

 LRL 

(μg/L)

Benchmark 

type

Benchmark 

level

(μg/L)

Detection

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

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

Dichlorodifluoromethane (CFC-12) Refrigerant 34668 75-71-8 0.1 NL-CA 1,000 D 3

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

1,2-Dichloroethane (1,2-DCA) Solvent 32103 107-06-2 0.08 MCL-CA 0.5 D

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

cis-1,2-Dichloroethene (cis-1,2-DCE) Solvent 77093 156-59-2 0.022 MCL-CA 6 —trans-1,2-Dichloroethene (trans-1,2-DCE) Solvent 34546 156-60-5 0.018 MCL-CA 10 —

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

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

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

1,1-Dichloropropene Organic synthesis 77168 563-58-6 0.040 na na —

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

trans-1,3-Dichloropropene Fumigant 34699 10061-02-6 0.14 RSD5-US 4 4 —Diethyl ether Solvent 81576 60-29-7 0.1 na na —

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

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

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

Ethyl methacrylate Organic synthesis 73570 97-63-2 0.20 na na —

o-Ethyl toluene (1-Ethyl-2-methyl benzene) Gasoline hydrocarbon 77220 611-14-3 0.032 na na —

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

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

2-Hexanone (n-Butyl methyl ketone) Solvent 77103 591-78-6 0.4 na na —

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

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

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

Methyl acrylate Organic synthesis 49991 96-33-3 0.8 na na —

Table 3A. Volatile organic compounds (VOCs), primary uses or sources, comparative benchmarks, and reporting information for the USGS National Water Quality Laboratory Schedule 2020.—Continued[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Laboratory reporting level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant level; NL-CA, CDPH notification level; RSD5-US, USEPA risk-specific dose at a risk factor of 10–5. Other abbreviations: USGS, U.S. Geological Survey; 

CAS, Chemical Abstract Service; LRL, laboratory reporting level; SRL, study reporting level; THM, trihalomethane; D, detected in groundwater samples (table 5); na, not available; μg/L, micrograms per liter; —, not detected]
24 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program Constituent (synonym or abbreviation) Primary use or source USGS parameter code CAS Registry Number® 1 LRL (μg/L) Benchmark type Benchmark level (μg/L) Detection Methyl acrylonitrile Organic synthesis 81593 126-98-7 0.26 na na

—

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

D

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

—

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

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

—

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

—

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

—

Perchloroethene (PCE, Tetrachloroethene) Solvent 34475 127-18-4 0.026 MCL-US 5 D

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

—

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

—

1,1,1,2-Tetrachloroethane Solvent 77562 630-20-6 0.040 HAL-US 70

—

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

Tetrahydrofuran Solvent 81607 109-99-9 1.4 na na

—

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

—

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

—

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

—

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

—

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

1,1,1-Trichloroethane (1,1,1-TCA) Solvent 34506 71-55-6 0.030 MCL-US 200

D

1,1,2-Trichloroethane (1,1,2-TCA) Solvent 34511 79-00-5 0.028 MCL-US 5 —

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

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

—

1,2,3-Trichloropropane (1,2,3-TCP) Solvent/organic synthesis 77443 96-18-4 0.12 HAL-US 5 40

—

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

D

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

—

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

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

—

Table 3A.

Volatile organic compounds (VOCs), primary uses or sources, comparative benchmarks, and reporting information for the USGS National Water Quality Laboratory 

Schedule 2020.—Continued[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Laboratory reporting level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant level; NL-CA, CDPH notification level; RSD5-US, USEPA risk-specific dose at a risk factor of 10–5. Other abbreviations: USGS, U.S. Geological Survey; 

CAS, Chemical Abstract Service; LRL, laboratory reporting level; SRL, study reporting level; THM, trihalomethane; D, detected in groundwater samples (table 5); na, not available; μg/L, micrograms per liter; —, not detected]
Tables 25

Constituent 

(synonym or abbreviation)

Primary use 

or source

USGS 

parameter 

code

CAS 

Registry Number® 1

 LRL 

(μg/L)

Benchmark 

type

Benchmark 

level

(μg/L)

Detection

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

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

m- and p-Xylene Gasoline hydrocarbon 85795 108-38-3 / 106-42-3 0.08 MCL-CA 7 1,750 —

o-Xylene Gasoline hydrocarbon 77135 95-47-6 0.032 MCL-CA 7 1,750 —

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

ServicesSM.

2 The MCL-US benchmark for trihalomethanes is the sum of chloroform, bromoform, bromodichloromethane, and dibromochloromethane.3 The median matrix-spike recovery was less than 70 percent. Low recoveries may indicate that the compound might not have been detected in some samples if it was present at very low concentrations.4 The RSD5 benchmark for 1,3-dichloropropene is the sum of its isomers (cis and trans).5 In earlier reports in this series, the NL-CA (0.005 μg/L) was used as the comparative benchmark for 1,2,3-TCP.6 All results for 1,2,4-trimethylbenzene were less than the SRL (0.56 μg/L) that was defined on the basis of the examination of quality-control samples collected for the first 32 GAMA study units (May 2004 

through September 2010) and in laboratory instrument and preparation blanks analyzed during the same time period as the samples (Fram and others, 2012).

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

Table 3A. Volatile organic compounds (VOCs), primary uses or sources, comparative benchmarks, and reporting information for the USGS National Water Quality Laboratory Schedule 2020.—Continued[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Laboratory reporting level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant level; NL-CA, CDPH notification level; RSD5-US, USEPA risk-specific dose at a risk factor of 10–5. Other abbreviations: USGS, U.S. Geological Survey; 

CAS, Chemical Abstract Service; LRL, laboratory reporting level; SRL, study reporting level; THM, trihalomethane; D, detected in groundwater samples (table 5); na, not available; μg/L, micrograms per liter; —, not detected]
26 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

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

USGS National Water Quality Laboratory Schedule 2003.

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

level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, 

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

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

RSD5-US, USEPA risk-specific dose at a risk factor of 10–5. Other abbreviations: USGS, U.S. Geological Survey; CAS, Chemical Abstract Service; 

LRL, laboratory reporting level; D, detected in groundwater samples (table 6); na, not available; μg/L, micrograms per liter; —, not detected]

Constituent 

(synonym or abbreviation)

Primary use 

or source

USGS 

parameter 

code

CAS Registry 

Number®

LRL 

(μg/L)

Benchmark 

type

Benchmark 

level 

(μg/L)

Detection

Acetochlor Herbicide 49260 34256-82-1 0.010 na na —

Alachlor Herbicide 46342 15972-60-8 0.008 MCL-US 2 —

Atrazine Herbicide 39632 1912-24-9 0.008 MCL-CA 1 —

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

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

Benfluralin Herbicide 82673 1861-40-1 0.014 na na — 1

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

2-Chloro-2,6-diethylacetanilide Herbicide degradate 61618 6967-29-9 0.010 na na —

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

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

Chlorpyrifos oxon Insecticide degradate 61636 5598-15-2 0.06 na na — 1

Cyfluthrin Insecticide 61585 68359-37-5 0.016 na na — 1

Cypermethrin Insecticide 61586 52315-07-8 0.020 na na — 1

Dacthal (DCPA) Herbicide 82682 1861-32-1 0.0076 HAL-US 70 —

Deethylatrazine 

(2-Chloro-4-isopropylamino-6-amino-s-triazine)

Herbicide degradate 04040 6190-65-4 0.006 na na —

Desulfinylfipronil Insecticide degradate 62170 na 0.012 na na —

Desulfinylfipronil amide Insecticide degradate 62169 na 0.029 na na —

Diazinon Insecticide 39572 333-41-5 0.0060 HAL-US 1 —

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

Dichlorvos Insecticide 38775 62-73-7 0.04 na na — 1

Dicrotophos Insecticide 38454 141-66-2 0.08 na na — 1

Dieldrin Insecticide 39381 60-57-1 0.008 RSD5-US 0.02 —

2,6-Diethylaniline Herbicide degradate 82660 579-66-8 0.0060 na na —

Dimethoate Insecticide 82662 60-51-5 0.006 na na — 1

Ethion Insecticide 82346 563-12-2 0.008 na na — 1

Ethion monoxon Insecticide degradate 61644 17356-42-2 0.021 na na —

2-Ethyl-6-methylaniline Herbicide degradate 61620 24549-06-2 0.010 na na —

Fenamiphos Insecticide 61591 22224-92-6 0.030 HAL-US 0.7 —

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

Fenamiphos sulfoxide Insecticide degradate 61646 31972-43-7 0.08 na na — 1

Fipronil Insecticide 62166 120068-37-3 0.018 na na —

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

Fipronil sulfone Insecticide degradate 62168 120068-36-2 0.024 na na — 1

Fonofos Insecticide 04095 944-22-9 0.0048 HAL-US 10 —

Hexazinone Herbicide 04025 51235-04-2 0.008 HAL-US 400 — 1

Iprodione Fungicide 61593 36734-19-7 0.014 na na — 1

Isofenphos Insecticide 61594 25311-71-1 0.006 na na —

Malaoxon Insecticide degradate 61652 1634-78-2 0.022 na na —

Malathion Insecticide 39532 121-75-5 0.016 HAL-US 500 —
Tables 27

Constituent 

(synonym or abbreviation)

Primary use 

or source

USGS 

parameter 

code

CAS Registry 

Number®

LRL 

(μg/L)

Benchmark 

type

Benchmark 

level 

(μg/L)

Detection

Metalaxyl Fungicide 61596 57837-19-1 0.014 na na —

Methidathion Insecticide 61598 950-37-8 0.012 na na —

Metolachlor Herbicide 39415 51218-45-2 0.020 HAL-US 700 —

Metribuzin Herbicide 82630 21087-64-9 0.012 HAL-US 70 —

Myclobutanil Fungicide 61599 88671-89-0 0.010 na na —

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

Paraoxon-methyl Insecticide degradate 61664 950-35-6 0.014 na na — 1

Parathion-methyl Insecticide 82667 298-00-0 0.008 HAL-US 1 —

Pendimethalin Herbicide 82683 40487-42-1 0.012 na na —

cis-Permethrin Insecticide 82687 54774-45-7 0.010 na na — 1

Phorate Insecticide 82664 298-02-2 0.020 na na — 1

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

Phosmet Insecticide 61601 732-11-6 0.14 na na — 1

Phosmet oxon Insecticide degradate 61668 3735-33-9 0.0511 na na — 1

Prometon Herbicide 04037 1610-18-0 0.012 HAL-US 400 —

Prometryn Herbicide 04036 7287-19-6 0.006 na na —

Pronamide (Propyzamide) Herbicide 82676 23950-58-5 0.0036 RSD5-US 10 —

Simazine Herbicide 04035 122-34-9 0.006 MCL-US 4 D

Tebuthiuron Herbicide 82670 34014-18-1 0.028 HAL-US 500 —

Terbufos Insecticide 82675 13071-79-9 0.018 HAL-US 0.4 — 1

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

Terbuthylazine Herbicide 04022 5915-41-3 0.0060 na na —

Tribufos Defoliant 61610 78-48-8 0.018 na na — 1

Trifluralin Herbicide 82661 1582-09-8 0.018 HAL-US 10 —

1

 The median matrix-spike recovery was less than 70 percent. Low recoveries may indicate that the compound might not have been detected in some samples 

if it was present at very low concentrations.

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

USGS National Water Quality Laboratory Schedule 2003.—Continued

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

level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, 

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

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

RSD5-US, USEPA risk-specific dose at a risk factor of 10–5. Other abbreviations: USGS, U.S. Geological Survey; CAS, Chemical Abstract Service; 

LRL, laboratory reporting level; D, detected in groundwater samples (table 6); na, not available; μg/L, micrograms per liter; —, not detected]
28 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Table 3C. Polar pesticides and degradates, primary uses or sources, comparative thresholds, and reporting information for the 

USGS National Water Quality Laboratory Schedule 2060.

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

level as of February 4, 2011. Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA 

when the MCL-CA is lower than the MCL-US or no MCL-US exists. Benchmark type: HAL-US, U.S. Environmental Protection Agency lifetime health 

advisory level; MCL-CA, California Department of Public Health (CDPH) 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. Other abbreviations: USGS, 

U.S. Geological Survey; CAS, Chemical Abstract Service; LRL, laboratory reporting level; na, not available; μg/L, micrograms per liter; —, not detected]

Constituent 

(synonym or abbreviation)

Primary 

use 

or source

USGS 

parameter 

code

CAS Registry 

Number®

LRL 

(μg/L)

Benchmark 

type

Benchmark 

level 

(μg/L)

Detection

Acifluorfen Herbicide 49315 50594-66-6 0.04 na na — 1

Aldicarb Insecticide 49312 116-06-3 0.12 HAL-US 2 7 — 1

Aldicarb sulfone Degradate 49313 1646-88-4 0.08 HAL-US 2 7 —

Aldicarb sulfoxide Degradate 49314 1646-87-3 0.06 HAL-US 2

 7 —

Atrazine Herbicide 39632 1912-24-9 0.04 MCL-CA 1 — 3

Bendiocarb Insecticide 50299 22781-23-3 0.04 na na —

Benomyl Fungicide 50300 17804-35-2 0.06 na na —

Bensulfuron-methyl Herbicide 61693 83055-99-6 0.06 na na —

Bentazon Herbicide 38711 25057-89-0 0.06 MCL-CA 18 — 1

Bromacil Herbicide 04029 314-40-9 0.06 HAL-US 70 —

Bromoxynil Herbicide 49311 1689-84-5 0.12 na na — 1

Caffeine Beverages 50305 58-08-2 4 0.10 na na —

Carbaryl Herbicide 49310 63-25-2 0.04 RSD5-US 400 —

Carbofuran Herbicide 49309 1563-66-2 0.04 MCL-CA 18 —

Chloramben methyl ester Herbicide 61188 7286-84-2 0.10 na na —

Chlorimuron-ethyl Herbicide 50306 90982-32-4 0.08 na na — 5

3-(4-Chlorophenyl)-1-methyl urea Degradate 61692 5352-88-5 0.06 na na —

Clopyralid Herbicide 49305 1702-17-6 0.06 na na — 1

Cycloate Herbicide 04031 1134-23-2 0.04 na na —

2,4-D Herbicide 39732 298-00-0 0.06 HAL-US 70 —

2,4-D methyl ester Herbicide 50470 na 0.2 na na —

2,4-D plus 2,4-D methyl ester Herbicides 66496 na 0.06 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 0.04 na na —

Deethylatrazine (2-Chloro-4-isopropylamino-6-amino-s-triazine) Degradate 04040 6190-65-4 0.06 na na — 3

Deisopropyl atrazine (2-Chloro-6-ethylamino-4-amino-s-triazine) Degradate 04038 1007-28-9 0.06 na na —

Dicamba Herbicide 38442 1918-00-9 0.04 HAL-US 4,000 — 1

Dichlorprop Herbicide 49302 120-36-5 0.04 na na —

Dinoseb (Dinitrobutyl phenol) Herbicide 49301 88-85-7 0.04 MCL-CA 7 — 1

Diphenamid Herbicide 04033 957-51-7 0.04 HAL-US 200 —

Diuron Herbicide 49300 330-54-1 0.04 RSD5-US 20 —

Fenuron Herbicide 49297 101-42-8 0.06 na na —

Flumetsulam Herbicide 61694 98967-40-9 0.06 na na —

Fluometuron Herbicide 38811 2164-17-2 0.04 HAL-US 90 —

Hydroxyatrazine 

(2-Hydroxy-4-isopropylamino-6-ethylamino-s-triazine)

Degradate 50355 2163-68-0 0.06 na na —

3-Hydroxycarbofuran Degradate 49308 16655-82-6 0.04 na na —

Imazaquin Herbicide 50356 81335-37-7 0.06 na na — 5

Imazethapyr Herbicide 50407 81335-77-5 0.06 na na — 5

Imidacloprid Insecticide 61695 138261-41-3 0.06 na na —
Tables 29

Constituent 

(synonym or abbreviation)

Primary 

use 

or source

USGS 

parameter 

code

CAS Registry 

Number®

LRL 

(μg/L)

Benchmark 

type

Benchmark 

level 

(μg/L)

Detection

Linuron Herbicide 38478 330-55-2 0.04 na na —

MCPA (2-Methyl-4-chlorophenoxyacetic acid) Herbicide 38482 94-74-6 0.04 HAL-US 30 —

MCPB (4-(2-Methyl-4-chlorophenoxy)butyric acid) Herbicide 38487 94-81-5 0.2 na na — 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 0.12 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 0.10 na na — 5

Norflurazon Herbicide 49293 27314-13-2 0.04 na na —

Oryzalin Herbicide 49292 19044-88-3 0.04 na na —

Oxamyl Insecticide 38866 23135-22-0 0.12 MCL-CA 50 —

Picloram Herbicide 49291 1918-02-01 0.12 MCL-US 500 — 1

Propham Herbicide 49236 122-42-9 0.04 HAL-US 100 —

Propiconazole Fungicide 50471 60207-90-1 0.04 na na —

Propoxur Insecticide 38538 114-26-1 0.06 HAL-US 3 —

Siduron Herbicide 38548 1982-49-6 0.04 na na — 5

Sulfometuron-methyl Herbicide 50337 74222-97-2 0.06 na na — 5

Tebuthiuron Herbicide 82670 34014-18-1 0.06 HAL-US 500 — 3

Terbacil Herbicide 04032 5902-51-2 0.04 HAL-US 90 —

Triclopyr Herbicide 49235 55335-06-3 0.08 na na —

1

 The median matrix-spike recovery was less than 70 percent. Low recoveries may indicate that the compound might not have been detected in some samples 

if it was present at very low concentrations.

2

 The HAL-US benchmark is the sum of aldicarb, aldicarb sulfone, and aldicarb sulfoxide.

3

 Constituent was measured on more than one schedule. See table 3B for results with preferred method.

4

 The California Groundwater Ambient Monitoring and Assessment (GAMA) Program uses more conservative reporting limits for the pharmaceutical 

compounds than are used by the USGS National Water Quality Laboratory (NWQL) (Fram and Belitz, 2011). The method detection limit (MDL) corresponds 

to the highest long-term method detection limit (LT-MDL) or interim method detection limit (I-MDL) used by the NWQL during the period GAMA samples 

were analyzed (May 2004 through June 2010). Results reported by the NWQL with concentrations less than the MDLs are reported as non-detections by 

GAMA. Data are stored in the USGS National Water Information System (NWIS) database as reported by GAMA: results initially reported as detections with 

concentrations below the MDLs or as non-detections less than LT-MDLs are re-coded as non-detections less than MDLs. 

5

 The median matrix-spike recovery was greater than 130 percent.

Table 3C. Polar pesticides and degradates, primary uses or sources, comparative thresholds, and reporting information for the 

USGS National Water Quality Laboratory Schedule 2060.—Continued

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

level as of February 4, 2011. Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA 

when the MCL-CA is lower than the MCL-US or no MCL-US exists. Benchmark type: HAL-US, U.S. Environmental Protection Agency lifetime health 

advisory level; MCL-CA, California Department of Public Health (CDPH) 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. Other abbreviations: USGS, 

U.S. Geological Survey; CAS, Chemical Abstract Service; LRL, laboratory reporting level; na, not available; μg/L, micrograms per liter; —, not detected]
30 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Table 3D. Pharmaceutical compounds, primary uses or sources, comparative benchmarks, and reporting information for the USGS 

National Water Quality Laboratory Schedule 2080.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Abbreviations: USGS, U.S. Geological Survey; 

CAS, Chemical Abstract Service; MDL, method detection level; na, not available; μg/L, micrograms per liter]

Constituent Primary use 

or source

USGS 

parameter 

code

CAS 

Registry 

Number®

MDL1

(μg/L)

Benchmark 

type

Benchmark 

level 

(μg/L)

Detection

Acetaminophen Analgesic 62000 103-90-2 0.06 na na —

Albuterol Bronchodilator 62020 18559-94-9 0.04 na na — 2

Caffeine Stimulant 50305 58-08-2 0.10 na na — 3

Carbamazapine Anticonvulsant; mood stabilizer 62793 298-46-4 0.03 na na —

Codeine Opiod narcotic 62003 76-57-3 0.023 na na —

Cotinine Nicotine metabolite 62005 486-56-6 0.019 na na —

Dehydronifedipine Antianginal metabolite 62004 67035-22-7 0.04 na na —

Diltiazem Antianginal; antihypertensive 62008 42399-41-7 0.04 na na — 2

1,7-Dimethylxanthine Caffeine metabolite 62030 611-59-6 0.06 na na —

Diphenydramine Antihistime 62796 147-25-0 0.02 na na —

Sulfamethoxazole Antibacterial 62021 723-46-6 0.08 na na — 2

Thiabendazole Anthelmintic 62801 148-79-8 0.03 na na —

Trimethoprim Antibacterial 62023 738-70-5 0.017 na na —

Warfarin Anticoagulant 62024 81-81-2 0.05 na na — 2

1

 The California Groundwater Ambient Monitoring and Assessment (GAMA) Program uses more conservative reporting limits for the pharmaceutical 

compounds than are used by the USGS National Water Quality Laboratory (NWQL) (Fram and Belitz, 2011). The method detection limit (MDL) corresponds to 

the highest long-term method detection limit (LT-MDL) or interim method detection limit (I-MDL) used by the NWQL during the period GAMA samples were 

analyzed (May 2004 through June 2010). Results reported by the NWQL with concentrations less than their MDLs are reported as non-detections by GAMA. 

Results for the Santa Barbara study unit for all pharmaceutical compounds on schedule 2080 were less than their respective MDL.

2

 The median matrix-spike recovery was less than 70 percent. Low recoveries may indicate that the compound might not have been detected in some samples 

if it was present at very low concentrations.

3

 Constituent was measured on more than one schedule. See table 3C for results with preferred method.

Table 3E. Constituents of special interest, primary uses or sources, comparative benchmarks, and reporting information for Weck 

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

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

level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, 

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

contaminant level; NL-CA, CDPH notification level. Other abbreviations: USGS, U.S. Geological Survey; CAS, Chemical Abstract Service; MRL, minimum 

reporting level; D, detected in groundwater samples (table 7); μg/L, micrograms per liter; —, not detected; SB, Santa Barbara grid well]

Constituent Primary use 

or source

USGS 

parameter 

code

CAS 

Registry 

Number®

MRL 

(μg/L)

Benchmark 

type

Benchmark 

level

(μg/L)

Detection

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

N-Nitrosodimethylamine (NDMA) Disinfection by-product 34438 62-75-9 0.0020 NL-CA 0.010 — 1

1

 Sample holding time exceeded for SB-05 and the associated field blank. NDMA might not have been detected in samples if it was present at very low 

concentrations.
Tables 31

Table 3F. Trace elements, comparative benchmarks, and reporting information for the USGS National Water Quality Laboratory 

Schedule 1948.

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

level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, 

and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. Secondary maximum contaminant level benchmarks are listed as 

SMCL-CA when the SMCL-CA exists, and as the SMCL-US when no SMCL-CA exists. AL-US, U.S. Environmental Protection Agency (USEPA) action level; 

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

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

U.S. Geological Survey; CAS, Chemical Abstract Service; LT-MDL, long-term method detection level; D, detected in groundwater samples (table 8); na, not 

available; μg/L, micrograms per liter; NWIS, USGS National Water Information System; NWQL, USGS National Water Quality Laboratory; BQS, USGS 

Branch of Quality Systems]

Constituent USGS 

parameter code

CAS Registry 

Number®

LT-MDL 

(μg/L)

Benchmark 

type

Benchmark level 

(μg/L) Detection

Aluminum 01106 7429-90-5 1.7 MCL-CA 1,000 D

Antimony 01095 7440-36-0 0.027 MCL-US 6 D

Arsenic 01000 7440-38-2 0.022 MCL-US 10 D

Barium 01005 7440-39-3 0.07 MCL-CA 1,000 D

Beryllium 01010 7440-41-7 0.006 MCL-US 4 D

Boron 01020 7440-42-8 3 NL-CA 1,000 D

Cadmium 01025 7440-43-9 0.016 MCL-US 5 D

Chromium 01030 7440-47-3 0.06 MCL-CA 50 D

Cobalt 01035 7440-48-4 0.02 na na D

Copper 01040 7440-50-8 0.5 AL-US 1,300 D

Iron 01046 7439-89-6 3.2 SMCL-CA 300 D

Lead 01049 7439-92-1 0.015 AL-US 15 D

Lithium 01130 7439-93-2 0.22 na na D

Manganese 01056 7439-96-5 0.13 SMCL-CA 50 D

Molybdenum 01060 7439-98-7 0.014 HAL-US 40 D

Nickel 01065 7440-02-0 0.09 MCL-CA 100 D

Selenium 01145 7782-49-2 0.03 MCL-US 50 D

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

Strontium 01080 7440-24-6 0.2 HAL-US 4,000 D

Thallium 01057 7440-28-0 0.010 MCL-US 2 D

Tungsten 01155 7440-33-7 0.010 na na D

Uranium 22703 7440-61-1 0.004 MCL-US 30 D

Vanadium 01085 7440-62-2 0.08 NL-CA 50 D

Zinc 01090 7440-66-6 1.4 SMCL-CA 5,000 D

Table 3G. Nutrients, comparative benchmarks, and reporting information for the USGS National Water Quality Laboratory 

Schedule 2755.

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

level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, 

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

health advisory level; MCL-US, USEPA maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; CAS, Chemical Abstract Service; 

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

Constituent USGS 

parameter code

CAS Registry 

Number®

LT-MDL 

(mg/L)

Benchmark 

type

Benchmark level 

(mg/L) Detection

Ammonia (as nitrogen) 00608 7664-41-7 0.010 HAL-US 1

 24.7 D

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

Nitrite (as nitrogen) 00613 14797-65-0 0.0010 MCL-US 1 D

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

Phosphate, orthophosphate (as phosphorus) 00671 14265-44-2 0.004 na na D

1

 The HAL-US is 30 mg/L “as ammonia.” To facilitate comparson to the analytical results, we have converted and reported this HAL-US as 24.7 mg/L “as 

nitrogen.”
32 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

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

for the USGS National Water Quality Laboratory Schedule 1948.

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

level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, 

and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. Secondary maximum contaminant level benchmarks are listed as 

SMCL-CA when the SMCL-CA exists, and as the SMCL-US when no SMCL-CA exists. MCL-CA, California Department of Public Health (CDPH) maximum 

contaminant level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; CAS, Chemical Abstract 

Service; LT-MDL, long-term method detection level; MRL, minimum reporting level; D, detected in groundwater samples (table 10); na, not available; 

mg/L, milligrams per liter]

Constituent

USGS 

parameter 

code

CAS 

Registry 

Number®

 LT-MDL, 

MDL, or MRL 

(mg/L)

Benchmark 

type

Benchmark 

level 

(mg/L)

Detection

Bromide 71870 24959-67-9 0.010 na na D

Calcium 00915 7440-70-2 0.022 na na D

Chloride 00940 16887-00-6 0.06 SMCL-CA 1

 250 (500) D

Fluoride 00950 16984-48-8 0.04 MCL-CA 2 D

Iodide 71865 7553-56-2 0.0010 na na D

Magnesium 00925 7439-95-4 0.008 na na D

Potassium 00935 7440-09-7 0.022 na na D

Silica (as SiO2

) 00955 7631-86-9 0.029 na na D

Sodium 00930 7440-23-5 0.06 na na D

Sulfate 00945 14808-79-8 0.09 SMCL-CA 1

 250 (500) D

Residue on evaporation (total dissolved solids, TDS) 70300 na 12 SMCL-CA 1

 500 (1,000) D

Laboratory alkalinity (as CaCO3

)2 29801 na 4.0 na na D

1

 The recommended SMCL-CA benchmarks for chloride, sulfate, and TDS are listed with the upper SMCL-CA benchmarks in parentheses.

2

 Laboratory alkalinity results are presented in table 4.

Table 3I. Arsenic, chromium, and iron species, comparative benchmarks, and reporting information for the USGS Trace Metal 

Laboratory, Boulder, Colorado, analyses.

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

level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, 

and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. Secondary maximum contaminant level benchmarks are listed as 

SMCL-CA when the SMCL-CA exists, and as the SMCL-US when no SMCL-CA exists. MCL-CA, California Department of Public Health (CDPH) maximum 

contaminant level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; CAS, Chemical Abstract 

Service; MDL, method detection limit; na, not available; μg/L, micrograms per liter; D, detected in groundwater samples (table 11)]

Constituent USGS 

parameter code

CAS Registry 

Number®

MDL 

(μg/L)

Benchmark 

type

Benchmark level 

(μg/L) Detection

Arsenic (total) 99033 7440-38-2 0.2 MCL-US 10 D

Arsenic (III) 99034 22569-72-8 0.5 na na D

Chromium (total) 01030 7440-47-3 0.1 MCL-CA 50 D

Chromium (VI) 01032 18540-29-9 0.1 na na D

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

Iron (II) 01047 7439-89-6 2 na na D
Tables 33

Table 3J. Isotope tracers and radioactive constituents, comparative benchmarks, and reporting information for laboratory analyses.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Laboratory entity codes in the USGS National Water 

Information System (NWIS) for laboratories other than the USGS National Water Quality Laboratory (NWQL) are given in parentheses after the laboratory 

names. 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. Method uncertainties for the isotope tracers are 2-sigmas; method uncertainties for radioactive constituents are 1-sigma. 

Benchmark type and benchmark value as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the 

MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. MCL-US, USEPA maximum 

contaminant level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level. Elements: H, hydrogen; O, oxygen; B, boron; 

Sr, strontium; C, carbon. Reporting units: pCi/L, picocuries per liter; pmc, percent modern carbon. Other abbreviations: USGS, U.S. Geological Survey; 

CAS, Chemical Abstract Service; na, not available; D, detected in groundwater samples (tables 12, 13A, and 13B); CSU, combined standard uncertainty]

Constituent USGS 

parameter code

CAS 

number

Method 

uncertainty

Reporting 

units Benchmark type Benchmark level 

(pCi/L) Detection

Isotope tracers

d2H in water 1 82082 na 2 per mil na na D

d18O in water 1 82085 na 0.20 per mil na na D

d11B in water 2 62648 na 2 per mil na na na

Strontium isotope ratio (87Sr/86Sr) 2 75978 na 0.0000 atom ratio na na na

d13C in dissolved inorganic carbon 3 82081 na 0.05 per mil na na D

Radioactive constituents 

Carbon-14 3 49933 14762-75-5 CSU pmc na na D

Tritium 4 07000 10028-17-8 CSU pCi/L MCL-CA 20,000 D

Radon-222 5 82303 14859-67-7 CSU pCi/L Proposed MCL-US 4,000 D

Gross alpha radioactivity, 

72-hour and 30-day counts 6

62636, 62639 12587-46-1 CSU pCi/L MCL-US 15 D

Gross beta radioactivity, 

 72-hour and 30-day counts 6

62642, 62645 12587-47-2 CSU pCi/L MCL-CA 50 D

1

 USGS Stable Isotope Laboratory, Reston, Virginia (USGSSIVA).

2

 USGS NRP Metals Isotope Research Laboratory, Menlo Park, California (USGSMICA).

3

 Woods Hole Oceanographic Institution, National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS), Woods Hole, Massachusetts 

(MA-WHAMS).

4

 USGS Stable Isotope and Tritium Laboratory, Menlo Park, California (USGSH3CA).

5

 USGS National Water Quality Laboratory (USGSNWQL).

6

 Eberline Analytical Services, Richmond, California (CA-EBERL).

Table 3K. Dissolved gases and isotope tracers, comparison benchmarks, and reporting information for Lawrence Livermore National 

Laboratory.

[The five-digit USGS parameter code is used to uniquely identify a specific constituent or property. Benchmark type and benchmark values as of February 4, 

2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when 

the MCL-CA is lower than the MCL-US or no MCL-US exists. MCL-US, USEPA maximum contaminant level; MCL-CA, California Department of Public 

Health (CDPH) maximum contaminant Level. Reporting units: cm3 STP/g, cubic centimeters of gas at standard temperature and pressure per gram of water; 

pCi/L, picocuries per liter. Other abbreviations: USGS, U.S. Geological Survey; CAS, Chemical Abstract Service; na, not available]

Constituent USGS parameter 

code

CAS 

number

Method 

uncertainty 

(percent)

Reporting 

units Benchmark type Benchmark level 

(pCi/L) Detection

Dissolved noble gases 

Argon 85563 7440-37-1 2 cm3

 STP/g na na na

Helium-4 85561 7440-59-7 2 cm3

 STP/g na na na

Krypton 85565 7439-90-9 2 cm3

 STP/g na na na

Neon 61046 7440-01-09 2 cm3

 STP/g na na na

Xenon 85567 7440-63-3 2 cm3

 STP/g na na na

Isotope tracers

Helium-3 / Helium-4 61040 na / 7440-59-7 0.75 atom ratio na na na

Tritium 07000 10028-17-8 1 pCi/L MCL-CA 20,000 na
34 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program Table 4.

Water-quality indicators in samples collected for the Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.

[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. GAMA well identification number: SB, Santa Barbara study unit grid well; SBU, Santa Barbara study unit understanding well. Reporting level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as SMCL-CA when the SMCL-CA exists, and as the SMCL-US when no SMCL-CA exists. SMCL-US, U.S. Environmental Protection Agency (USEPA) secondary maximum contaminant level; SMCL-CA, California Department of Public Health (CDPH) secondary maximum contaminant level. Other abbreviations: °C, degree Celsius; E, estimated or having a higher degree of uncertainty; mg/L, milligrams per liter; nc, not collected; na, not available; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium carbonate; HCO3

–, bicarbonate; CO32–, carbonate; *, value greater than benchmark 

level; **, value greater than upper benchmark level; —, not detected]

GAMA well 

identification 

number

Dissolved 

oxygen, 

field 

(mg/L) 

(00300) 

Water 

temperature, 

field 

(°C) 

(00010)

pH, 

laboratory 

(standard 

units) 

(00403)

pH, field 

(standard 

units) 

(00400)

Specific 

conductance, 

laboratory 

(μS/cm at 25°C) 

(90095)

Specific 

conductance, 

field 

(μS/cm at 25°C) 

(00095)

Alkalinity, 

laboratory 

(mg/L as 

CaCO3) 

(29801)

Alkalinity, 

field 

(mg/L as 

CaCO3) 

(29802)

Bicarbonate, 

field 

(mg/L as 

HCO3

–) 

(63786)

Bicarbonate, 

calculated from 

laboratory data 

(mg/L 

as HCO3

–

)

Carbonate, 

field 

(mg/L as 

CO32–) 

(63788)

Carbonate, 

calculated from 

laboratory data 

(mg/L 

as CO32–)

Benchmark type na na SMCL-US SMCL-US SMCL-CA SMCL-CA na na na na na naBenchmark level na na <6.5 or >8.5 <6.5 or >8.5 1 900 (1,600) 1 900 (1,600) na na na na na na

[Reporting level or range] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [4.0] [1] [1] [1] [0.1] [0.1]

Santa Barbara grid wells (18 wells sampled)

SB-01 0.2 20.0 7.1 7.0 ** 2,540 ** 2,510 373 nc na 454 na 0.3

SB-02 0.2 19.5 7.3 7.1 *1,250 *1,240 348 328 398 424 0.4 0.4

SB-03 0.3 18.5 7.3 7.1 *1,330 *1,320 281 nc na 342 na 0.3

SB-04 0.7 18.0 7.2 6.9 *925 *925 232 nc na 282 na 0.2

SB-05 5.1 19.5 7.2 7.0 **1,800 ** 1,800 183 nc na 223 na 0.2

SB-06 0.2 22.0 7.4 7.2 *1,310 *1,300 322 nc na 392 na 0.4

SB-07 3.3 21.0 7.2 6.8 ** 2,080 ** 2,090 324 nc na 394 na 0.3

SB-08 0.2 22.0 7.0 6.6 789 794 232 nc na 283 na 0.1

SB-09 3.3 21.0 6.5 *6.4 593 619 97 nc na 119 na

—

SB-10 0.3 19.0 6.5 *6.3 **1,640 ** 1,660 218 nc na 265 na

—

SB-11 3.1 17.0 7.0 6.9 *1,080 *1,080 268 nc na 326 na 0.2

SB-12 3.8 17.5 6.6 *6.4 *1,400 *1,400 276 nc na 336 na 0.1

SB-13 3.2 21.0 6.8 6.7 ** 2,170 ** 2,140 209 nc na 255 na 0.1

SB-14 0.2 21.0 7.7 7.5 *1,110 *1,080 357 331 402 434 1.1 1.0SB-15 0.4 20.5 7.5 7.2 827 817 289 nc na 351 na 0.5

SB-16 0.6 18.0 7.4 7.2 * 973 * 943 283 nc na 345 na 0.4

SB-17 4.7 16.0 7.2 7.0 *1,490 *1,490 356 nc na 433 na 0.3

SB-18 2.3 17.5 7.4 7.1 *1,280 *1,240 358 nc na 435 na 0.5
Tables 35

GAMA well 

identification 

number

Dissolved 

oxygen, 

field 

(mg/L) 

(00300) 

Water 

temperature, 

field 

(°C) 

(00010)

pH, 

laboratory 

(standard 

units) 

(00403)

pH, field 

(standard 

units) 

(00400)

Specific 

conductance, 

laboratory 

(μS/cm at 25°C) 

(90095)

Specific 

conductance, 

field 

(μS/cm at 25°C) 

(00095)

Alkalinity, 

laboratory 

(mg/L as 

CaCO3) 

(29801)

Alkalinity, 

field 

(mg/L as 

CaCO3) 

(29802)

Bicarbonate, 

field 

(mg/L as 

HCO3–) 

(63786)

Bicarbonate, 

calculated from 

laboratory data 

(mg/L 

as HCO3–)

Carbonate, 

field 

(mg/L as 

CO32–) 

(63788)

Carbonate, 

calculated from 

laboratory data 

(mg/L 

as CO32–)

Benchmark type na na SMCL-US SMCL-US SMCL-CA SMCL-CA na na na na na naBenchmark level na na <6.5 or >8.5 <6.5 or >8.5 1 900 (1,600) 1 900 (1,600) na na na na na na

[Reporting level or range] [0.2] [0.0–38.5] [0–14] [0–14] [5] [5] [4.0] [1] [1] [1] [0.1] [0.1]

Santa Barbara understanding wells (6 wells sampled)

SBU-01 0.2 23.5 7.3 7.2 *1,090 *1,080 298 nc na 362 na 0.4

SBU-02 0.2 23.0 7.6 7.6 ** 4,810 ** 4,810 246 nc na 299 na 0.6

SBU-03 < 0.2 23.0 7.8 7.4 * 917 * 935 335 nc na 406 na 1.2

SBU-04 0.7 21.5 7.2 6.9 645 653 229 nc na 279 na 0.2

SBU-05 1.8 21.0 7.0 6.7 897 * 905 194 176 214 236 — 0.1

SBU-06 0.4 21.0 7.3 7.0 * 994 * 999 195 nc na 238 na 0.2

1 The SMCL-CA for specific conductance has recommended and upper benchmark values. The upper value is shown in parentheses.

Table 4. Water-quality indicators in samples collected for the Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. GAMA well identification number: SB, Santa Barbara study unit grid well; SBU, Santa Barbara study unit understanding well. Reporting level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as SMCL-CA when the SMCL-CA exists, and as the SMCL-US when no SMCL-CA exists. SMCL-US, U.S. Environmental Protection Agency (USEPA) secondary maximum contaminant level; SMCL-CA, California Department of Public Health (CDPH) secondary maximum contaminant level. Other abbreviations: °C, degree Celsius; E, estimated or having a higher degree of uncertainty; mg/L, milligrams per liter; nc, not collected; na, not available; μS/cm, microsiemens per centimeter; <, less than; >, greater than; CaCO3, calcium carbonate; HCO3–, bicarbonate; CO32–, carbonate; *, value greater than benchmark 

level; **, value greater than upper benchmark level; —, not detected]
36 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program Table 5.

Volatile organic compounds (VOCs) detected in samples collected for the Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.

[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 24 wells were analyzed, but only samples with detections are listed. Constituents are listed in order of decreasing detection frequency in the 18 grid wells. All analytes are listed in table 3A. GAMA well identification number: SB, Santa Barbara study unit grid well; SBU, Santa Barbara study unit understanding well. Reporting level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; NL-CA, CDPH notification level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; μg/L, microgram per liter; na, not available; —, not detected; NWIS, USGS National 

Water Information System]

Primary use or source Disinfection byproducts Solvents Gasoline oxygenate Refrigerant

GAMA well 

identification 

number

Chloroform 

(Trichloromethane) 

(μg/L) 

(32106)

Bromodichloromethane 

(μg/L) 

(32101)

1,1,1-Trichloroethane 

(μg/L) 

(34506)

1,1-Dichloroethane 

(μg/L) 

(34496)

Perchloroethene 

(μg/L) 

(34475)

Methyl tert-butyl ether 

(μg/L) 

(78032)

Trichlorotrifluoroethane 

(CFC-113) 

(μg/L) 

(77652)

Benchmark type MCL-US MCL-US MCL-US MCL-CA MCL-CA MCL-CA MCL-CA

Benchmark level 2 80 2 80 200 5 5 13 1,200

[LRL] [0.03] [0.034] [0.03] [0.044] [0.026] [0.1] [0.034]

Santa Barbara grid wells (18 wells sampled)

SB-03 0.30

—

—

—

—

—

—

SB-04 21.8

—

—

—

—

—

—

SB-05 0.09

—

—

—

—

—

—

SB-07 0.06

—

— 0.044 0.022

— 1.7

SB-08

—

—

—

—

— 9.1

—

SB-09 0.09

—

—

—

—

—

—

SB-10

—

—

— 0.021

— 1.9

—

SB-12 1.78 0.27 0.01

— 0.012

—

—

SB-15 0.02

—

—

—

—

—

—

SB-17 0.13

— 0.05

—

—

—

—

SB-18 0.51 0.067

—

—

—

—

—

Number of wells with 

detections

9 2 2 2 2 2 1

Detection frequency (percent) 50 11 11 11 11 11 5.6Total number of detections

Santa Barbara understanding wells (6 wells sampled) 3

SBU-05 0.04

—

—

— 0.78

—

—
Tables 37

Primary use or source Solvents Refrigerant

Detections 

per well

VOC detection 

summary 1

GAMA well 

identification 

number

1,2-Dichloroethane 

(μg/L) 

(32103)

Dibromomethane 

(μg/L) 

(30217)

Carbon tetrachloride 

(tetrachloromethane) 

(μg/L) 

(32102)

Dichlorodifluoromethane 

(CFC-12) 

(μg/L) 

(34668)

Benchmark type MCL-CA na MCL-CA NL-CABenchmark level 0.5 na 0.5 1,000

[LRL] [0.08] [0.05] [0.06] [0.1]

Santa Barbara grid wells (18 wells sampled)

SB-03 — — — — 1

SB-04 — — — — 1

SB-05 — — — — 1

SB-07 — — — — 4

SB-08 — — — — 1

SB-09 — — — — 1

SB-10 0.07 — — — 3

SB-12 — 0.03 — — 5

SB-15 — — — — 1

SB-17 — — — — 2

SB-18 — — — — 2Number of wells with detections 1 1 0 0 11

Detection frequency (percent) 5.6 5.6 0 0 61

Total number of detections 22

Santa Barbara understanding wells (6 wells sampled) 3

SBU-05 — — 0.16 E0.07 3

1 Raw results for VOCs included four detections for 1,2,4-trimethylbenzene that were less than the study reporting level (SRL) of 0.56 μg/L. The SRL was determined on the basis of the qualitycontrol data collected between May 2004 and September 2010 for the first 32 study units of the California GAMA Priority Basin Project (Fram and others, 2012). 1,2,4-trimethylbenzene was detected 

at concentrations (in micrograms per liter) less than the SRL for SB-02 (0.038), SB-03 (0.071), SB-04 (0.027), and SB-16 (0.032). In the USGS NWIS database, the results are accompanied with the following comment: Result is < or = reported value, based on quality-control data.

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

Table 5. Volatile organic compounds (VOCs) detected in samples collected for the Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Samples from all 24 wells were analyzed, but only samples with detections are listed. Constituents are listed in order of decreasing detection frequency in the 18 grid wells. All analytes are listed in table 3A. GAMA well identification number: SB, Santa Barbara study unit grid well; SBU, Santa Barbara study unit understanding well. Reporting level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. MCL-US, U.S. Environmental Protection Agency maximum contaminant level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; NL-CA, CDPH notification level. Other abbreviations: E, estimated or having a higher degree of uncertainty; LRL, laboratory reporting level; μg/L, microgram per liter; na, not available; —, not detected; NWIS, USGS National Water Information System]
38 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Table 6. Pesticides and pesticide degradates detected in 

samples collected for the Santa Barbara study unit, January to 

February 2011, California GAMA Priority Basin Project.

[The five-digit U.S. Geological Survey (USGS) parameter code below the 

constituent name is used to uniquely identify a specific constituent or property. 

Samples from 24 wells were analyzed, but only samples with detections 

are listed. All analytes are listed in table 3B. GAMA well identification 

number: SB, Santa Barbara study unit grid well. Laboratory reporting level, 

benchmark type, and benchmark level as of February 4, 2011. Benchmark 

type: Maximum contaminant level benchmarks are listed as MCL-US when 

the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA 

is lower than the MCL-US or no MCL-US exists. MCL-CA, California 

Department of Public Health (CDPH) maximum contaminant level; MCL-US, 

U.S. Environmental Protection Agency maximum contaminant level. Other 

abbreviations: E, estimated or having a higher degree of uncertainty; 

LRL, laboratory reporting level; μg/L, micrograms per liter]

Primary use or source Herbicide 

Pesticide 

detections 

per well

Pesticide 

detection 

summary

GAMA well 

identification 

number

Simazine 

(μg/L) 

(04035)

Benchmark type MCL-US

Benchmark level 4

[LRL] [0.006]

Santa Barbara grid wells (18 wells sampled) 

SB-04 E0.005 1

SB-17 E0.004 1

Number of wells with detections 2 2

Detection frequency (percent) 11 11

Total number of detections 2

Table 7. Perchlorate detected in the samples collected for the 

Santa Barbara study unit, January to February 2011, California 

GAMA Priority Basin Project.

[The five-digit U.S. Geological Survey (USGS) parameter code below the 

constituent name is used to uniquely identify a specific constituent or property. 

Information about the constituent is given in table 3E. Samples from all 

24 wells were analyzed for perchlorate, but only samples with detections 

are listed. GAMA well identification number: SB, Santa Barbara study 

unit grid well; SBU, Santa Barbara study unit understanding well. Minimum 

reporting level, benchmark type, and benchmark level as of February 4, 

2011. Benchmark type: Maximum contaminant level benchmarks are 

listed as MCL-US when the MCL-US and MCL-CA are identical, and as 

MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US 

exists. MCL-CA, California Department of Public Health (CDPH) maximum 

contaminant level. Other abbreviations: MRL, minimum reporting level; 

μg/L, microgram per liter]

GAMA well 

identification 

number

Perchlorate 

(μg/L) 

(63790)

Benchmark type MCL-CA

Benchmark level 6

[MRL] [0.10]

Santa Barbara grid wells (18 wells sampled)

SB-05 3.90

SB-07 1.65

SB-08 0.34

SB-09 1.09

SB-10 1.03

SB-11 0.54

SB-12 0.88

SB-13 2.18

SB-15 1.32

SB-16 2.54

SB-17 0.57

SB-18 0.90

Number of wells with detections 12

Detection frequency (percent) 67

Santa Barbara understanding wells (6 wells sampled)

SBU-05 1.43

SBU-06 0.24
Tables 39

Table 8. Trace elements detected in the samples collected for the Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Information about the analytes given in table 3F. GAMA well identification number: SB, Santa Barbara study unit grid well; SBU, Santa Barbara study unit understanding well. Method detection level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. Secondary maximum contaminant level benchmarks are listed as SMCL-CA when the SMCL-CA exists, and as MCL-US when the SMCL-CA does not exist. AL-US, U.S. Environmental Protection Agency (USEPA) action level; HAL-US, USEPA lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant level; NL-CA, CDPH notification level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; LT-MDL, long-term method detection level; SRL, study reporting level; μg/L, micrograms per liter; —, not detected; ≤, less than or equal to; *, value above benchmark level; NWIS, USGS National Water Information System]

GAMA well 

identification 

number

Aluminum 

(μg/L) 

(01106) 

Antimony 

(μg/L) 

(01095) 

Arsenic 

(μg/L) 

(01000) 

Barium 

(μg/L) 

(01005) 

Beryllium 

(μg/L) 

(01010)

Boron 

(μg/L) 

(01020) 

Cadmium 

(μg/L) 

(01025) 

Chromium 

(μg/L) 

(01030) 

Cobalt 

(μg/L) 

(01035) 

Copper 

(μg/L) 

(01040) 

Iron 

(μg/L) 

(01046) 

Lead 

(μg/L) 

(01049) 

Benchmark type MCL-CA MCL-US MCL-US MCL-CA MCL-US NL-CA MCL-US MCL-CA na AL-US SMCL-CA AL-USBenchmark level 1,000 6 10 1,000 4 1,000 5 50 na 1,300 300 15[LT-MDL] or [SRL] [1.7] [0.027] [0.022] 1 [0.36] [0.006] [3] [0.016] 1 [0.42] 2 [0.22] 1 [1.7] 1 [6.0] 1 [0.65]

Santa Barbara grid wells (18 wells sampled)

SB-013 — — 0.26 21 — 399 — — ≤0.14 — * 1,220 —

SB-02 5.2 0.08 1.1 50 — 131 0.02 — 0.23 ≤0.56 * 1,240 ≤0.45

SB-03 3.1 0.40 2.3 157 — 115 0.03 ≤0.18 0.76 — 265 ≤0.07

SB-04 2.3 0.17 0.64 77 — 158 0.05 ≤0.10 ≤0.08 ≤0.92 90.9 ≤0.41

SB-05 — — 0.40 92 — 44 0.03 1.1 ≤0.07 5.3 6.1 0.80

SB-06 1.9 0.10 0.46 50 — 147 — ≤0.06 0.42 ≤0.56 168 —

SB-07 — — 0.38 40 0.007 181 0.04 0.63 ≤0.08 3.7 66.0 ≤0.29

SB-08 — — 0.37 42 — 44 0.02 ≤0.11 ≤0.06 6.0 ≤5.3 ≤0.23

SB-09 3.7 — 0.15 146 0.009 28 — ≤0.36 ≤0.04 13.0 — 5.3SB-10 2.3 — 0.35 193 0.009 151 0.13 ≤0.10 0.95 5.1 ≤5.1 ≤0.62

SB-11 — — 0.11 103 0.007 271 — ≤0.15 ≤0.07 ≤1.1 ≤5.7 ≤0.64

SB-12 — — 0.09 91 0.007 186 0.02 ≤0.14 ≤0.09 5.1 — ≤0.32

SB-13 — — 0.19 94 — 98 0.07 ≤0.09 ≤0.12 5.3 170 1.0

SB-14 4.0 — 0.09 360 0.034 * 1,110 — — ≤0.02 — * 369 —

SB-15 — — 0.79 74 — 104 0.02 ≤0.24 ≤0.05 — 21.4 ≤0.36

SB-16 — 0.04 0.75 59 — 75 0.02 0.45 ≤0.07 ≤0.75 73.4 ≤0.64

SB-17 — 0.03 0.05 17 — 96 — ≤0.10 ≤0.13 — ≤3.6 —SB-18 — — 0.42 55 0.006 269 — ≤0.33 ≤0.08 4.4 9.6 1.1
40 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program GAMA well identification number Aluminum (μg/L) (01106) Antimony (μg/L) (01095) Arsenic (μg/L) (01000) Barium (μg/L) (01005) Beryllium (μg/L) (01010) Boron (μg/L) (01020) Cadmium (μg/L) (01025) Chromium (μg/L) (01030) Cobalt (μg/L) (01035) Copper (μg/L) (01040) Iron (μg/L) (01046) Lead (μg/L) (01049) Benchmark type MCL-CA MCL-US MCL-US MCL-CA MCL-US NL-CA MCL-US MCL-CA na AL-US SMCL-CA AL-US Benchmark level 1,000 6 10 1,000 4 1,000 5 50 na 1,300 300 15 [LT-MDL] or [SRL] [1.7] [0.027] [0.022] 1 [0.36] [0.006] [3] [0.016] 1 [0.42] 2 [0.22] 1 [1.7] 1 [6.0] 1 [0.65] Santa Barbara understanding wells (6 wells sampled) SBU-01

—

— 0.39 33

— 58

—

— ≤0.05

— * 413 ≤0.19

SBU-023 3.7

— 0.35 * 4,770 0.14 * 7,560

— ≤0.12 ≤0.05

—

—

—

SBU-03 2.5

— 0.14 145

— 106

—

— ≤0.04

—

—

—

SBU-04

—

— 0.27 49

— 35 0.02 ≤0.13 ≤0.04 ≤0.69 10.6 0.74

SBU-05

—

— 0.23 68

— 35

— ≤0.38 ≤0.07 ≤1.6

— 1.11

SBU-06

—

— 2.3 67

— 51 0.02 ≤0.10 ≤0.06

— 209 ≤0.17

Table 8. Trace elements detected in the samples collected for the Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Information about the analytes given in table 3F. GAMA well identification number: SB, Santa Barbara study unit grid well; SBU, Santa Barbara study unit understanding well. Method detection level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. Secondary maximum contaminant level benchmarks are listed as SMCL-CA when the SMCL-CA exists, and as MCL-US when the SMCL-CA does not exist. AL-US, U.S. Environmental Protection Agency (USEPA) action level; HAL-US, USEPA lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant level; NL-CA, CDPH notification level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; LT-MDL, long-term method detection level; SRL, study reporting level; μg/L, micrograms per liter; —, not detected; ≤, less than or equal to; *, value above benchmark level; NWIS, USGS National 

Water Information System]
Tables 41

GAMA well 

identification 

number

Lithium 

(μg/L) 

(01130) 

Manganese 

(μg/L) 

(01056) 

Molybdenum 

(μg/L) 

(01060) 

Nickel 

(μg/L) 

(01065) 

Selenium 

(μg/L) 

(01145) 

Silver 

(μg/L) 

(01075) 

Strontium 

(μg/L) 

(01080)

Thallium 

(μg/L) 

(01057) 

Tungsten 

(μg/L) 

(01155)

Uranium 

(μg/L) 

(22703)

Vanadium 

(μg/L) 

(01085) 

Zinc 

(μg/L) 

(01090)

Benchmark type na SMCL-CA HAL-US MCL-CA MCL-US SMCL-CA HAL-US MCL-US na MCL-US NL-CA SMCL-CABenchmark level na 50 40 100 50 100 4,000 2 na 30 50 5,000

[LT-MDL] or [SRL] [0.22] 2 [0.47] [0.014] 1 [0.36] [0.03] [0.005] [0.2] [0.010] 1 [0.11] [0.004] 1 [0.10] 1 [4.8] 

Santa Barbara grid wells (18 wells sampled)

SB-013 106 * 182 5.3 0.94 0.32 — 3,440 — — 0.70 0.24 —

SB-02 25.5 * 245 3.7 2.6 0.08 — 1,410 — 0.11 14.4 0.61 ≤3.4

SB-03 40.1 * 59.6 5.6 2.9 4.9 — 1,400 — 1.7 13.5 6.5 73.7

SB-04 18.3 26.2 4.6 1.1 24.5 — 904 — 0.18 3.37 2.0 5.2

SB-05 30.9 ≤0.23 0.7 0.6 1.7 0.006 1,290 — ≤0.01 1.01 1.8 17.0

SB-06 70.7 7.6 1.3 1.0 1.5 — 1,300 — ≤0.08 8.13 0.40 —

SB-07 46.8 3.5 5.8 0.7 5.8 0.005 1,670 — — 7.69 1.3 32.3

SB-08 41.8 43.5 1.4 0.6 3.2 — 574 — — 0.62 1.1 ≤1.6

SB-09 27.0 ≤0.16 0.3 1.0 4.4 — 371 — ≤0.01 0.04 0.82 5.5

SB-10 30.1 * 190 0.4 4.4 0.20 — 688 — ≤0.02 0.20 1.2 11.4

SB-11 21.1 — 0.6 0.71 1.1 — 804 — — 1.92 0.60 7.6

SB-12 21.9 — 0.3 1.1 0.77 0.008 1,410 — ≤0.03 1.32 0.51 ≤4.4

SB-13 41.3 13.4 0.6 1.5 6.4 0.006 1,430 — — 1.42 0.83 146

SB-14 100 * 103 0.4 ≤0.22 — 0.005 1,580 — 1.4 0.04 0.23 —

SB-15 17.0 * 96 1.9 ≤0.17 0.46 — 700 — ≤0.02 1.56 1.2 ≤1.8

SB-16 13.5 * 249 0.9 1.2 2.5 — 733 — — 2.91 0.85 14.2

SB-17 20.9 17.0 1.0 1.7 0.48 — 311 — ≤0.05 0.27 — —SB-18 35.3 18.8 3.0 1.8 4.6 — 1,350 — ≤0.02 12.2 1.7 60.7

Table 8. Trace elements detected in the samples collected for the Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Information about the analytes given in table 3F. GAMA well identification number: SB, Santa Barbara study unit grid well; SBU, Santa Barbara study unit understanding well. Method detection level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. Secondary maximum contaminant level benchmarks are listed as SMCL-CA when the SMCL-CA exists, and as MCL-US when the SMCL-CA does not exist. AL-US, U.S. Environmental Protection Agency (USEPA) action level; HAL-US, USEPA lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant level; NL-CA, CDPH notification level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; LT-MDL, long-term method detection level; SRL, study reporting level; μg/L, micrograms per liter; —, not detected; ≤, less than or equal to; *, value above benchmark level; NWIS, USGS National Water Information System]
42 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program GAMA well identification number Lithium (μg/L) (01130) Manganese (μg/L) (01056) Molybdenum (μg/L) (01060) Nickel (μg/L) (01065) Selenium (μg/L) (01145) Silver (μg/L) (01075) Strontium (μg/L) (01080) Thallium (μg/L) (01057) Tungsten (μg/L) (01155) Uranium (μg/L) (22703) Vanadium (μg/L) (01085) Zinc (μg/L) (01090) Benchmark type na SMCL-CA HAL-US MCL-CA MCL-US SMCL-CA HAL-US MCL-US na MCL-US NL-CA SMCL-CA Benchmark level na 50 40 100 50 100 4,000 2 na 30 50 5,000 [LT-MDL] or [SRL] [0.22] 2 [0.47] [0.014] 1 [0.36] [0.03] [0.005] [0.2] [0.010] 1 [0.11] [0.004] 1 [0.10] 1 [4.8] Santa Barbara understanding wells (6 wells sampled) SBU-01 16.2 * 63.4 1.0 1.3 0.03

— 1,090

— ≤0.02 0.03 ≤0.08 5.8

SBU-023 177 23.5 0.1 ≤0.26 0.11 0.011 * 4,460 0.03 0.70

— 1.6

—

SBU-03 33.6 * 50 0.015 ≤0.27

—

— 727

— 0.98 0.05 ≤0.10

—

SBU-04 20.8 1.2 2.2 ≤0.35 0.35

— 505

— 0.17 0.80 1.2 11.0

SBU-05 21.7

— 1.1 0.83 1.2

— 639

—

— 0.74 1.1 15.7

SBU-06 22.9 * 240 2.0 0.42 0.22

— 850

—

— 0.52 0.54 8.8

1 SRL defined based on examination of GAMA quality-control samples collected from May 2004 through January 2008 (Olsen and others, 2010). Values less than the SRL are reported as less than or equal to 

(≤) the value reported by the laboratory. In the USGS NWIS database, the result is accompanied with the following comment: Result is ≤ reported value, based on quality-control data collected for this study.

2 SRL defined as the highest concentration detected in field blanks collected for the Santa Barbara study unit. Values less than the SRL are reported as less than or equal to (≤) the value reported by the 

laboratory. In the USGS NWIS database, the result is accompanied with the following comment: Result is ≤ reported value, based on quality-control data collected for this study.

3 For samples SB-01 and SBU-02, LT-MDLs reported by the NWQL raised by a factor of two due to dilution during analyses for all trace elements except iron.

Table 8. Trace elements detected in the samples collected for the Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.—Continued[The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. Information about the analytes given in table 3F. GAMA well identification number: SB, Santa Barbara study unit grid well; SBU, Santa Barbara study unit understanding well. Method detection level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. Secondary maximum contaminant level benchmarks are listed as SMCL-CA when the SMCL-CA exists, and as MCL-US when the SMCL-CA does not exist. AL-US, U.S. Environmental Protection Agency (USEPA) action level; HAL-US, USEPA lifetime health advisory level; MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; MCL-US, USEPA maximum contaminant level; NL-CA, CDPH notification level; SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: USGS, U.S. Geological Survey; LT-MDL, long-term method detection level; SRL, study reporting level; μg/L, micrograms per liter; —, not detected; ≤, less than or equal to; *, value above benchmark level; NWIS, USGS National 

Water Information System]
Tables 43

Table 9. Nutrients detected in samples collected for the Santa Barbara study unit, January to February 2011, California GAMA Priority 

Basin Project.

[The five-digit U.S. Geological Survey parameter code below the constituent name is used to uniquely identify a specific constituent or property. Information 

about the analytes given in table 3G. GAMA well identification number: SB, Santa Barbara study unit grid well; SBU, Santa Barbara study unit understanding 

well. Long-term method detection level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level 

benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no 

MCL-US exists. HAL-US, U.S. Environmental Protection Agency (USEPA) lifetime health advisory level; MCL-US, USEPA maximum contaminant level. 

Other abbreviations: LT-MDL, long-term method detection level; SRL, study unit reporting level; mg/L, milligrams per liter; na, not available; —, not 

detected]

GAMA well 

identification 

number

Ammonia, 

as nitrogen 

(mg/L) 

(00608)

 Nitrite, 

as nitrogen 

(mg/L) 

(00613)

Nitrite plus nitrate, 

as nitrogen 

(mg/L) 

(00631)

Total nitrogen 

(ammonia + nitrate + nitrite + 

organic nitrogen) 

(mg/L) 

(62854) 1

Phosphate, 

orthophosphate 

(as phosphorus) 

(mg/L) 

(00671)

Benchmark type HAL-US MCL-US MCL-US na na

Benchmark level 2

 24.7 1 10 na na

[LT-MDL] or [SRL] 3

 [0.013] [0.0010] [0.02] [0.05] [0.004]

Santa Barbara grid wells (18 wells sampled)

SB-01 2.98 0.0011 — 3.24 0.052

SB-02 0.533 — — 0.57 0.123

SB-03 0.104 — — 0.14 0.018

SB-04 — 0.0057 0.41 0.44 0.088

SB-05 — 0.0021 4.10 3.97 0.035

SB-06 0.496 — — 0.51 0.068

SB-07 — 0.0011 4.29 4.42 0.063

SB-08 — 0.0029 1.62 1.61 0.093

SB-09 — — 3.38 3.55 0.070

SB-10 — 0.0043 7.39 7.63 0.157

SB-11 — — 1.86 1.84 0.028

SB-12 — — 3.80 4.03 0.025

SB-13 — 0.0032 6.11 6.17 0.026

SB-14 0.063 — — 0.06 0.052

SB-15 0.047 0.0017 1.80 1.84 0.050

SB-16 0.018 0.0045 7.10 7.35 0.051

SB-17 — — 4.32 4.31 0.030

SB-18 — 0.0018 3.22 3.27 0.031

Santa Barbara understanding wells (6 wells sampled)

SBU-01 0.115 — — 0.12 0.047

SBU-02 0.746 — — 0.80 0.027

SBU-03 0.079 — — 0.08 0.067

SBU-04 — — 0.18 0.17 0.065

SBU-05 0.019 — 7.75 7.78 0.105

SBU-06 0.083 0.0358 0.26 0.34 0.063

1

 Using the raw results, total nitrogen concentration was compared with the sum of ammonia concentration and nitrite plus nitrate concentration: for total 

nitrate concentration greater than 0.25 mg/L (5 times LT-MDL), relative standard deviation less than 10 percent indicates acceptable results; for total nitrate 

concentration less than or equal to 0.25 mg/L, standard deviation less than 0.025 mg/L (1⁄2 LT-MDL) indicates acceptable results. All nutrient results for the Santa 

Barbara study unit met the acceptablility criteria.

2

 The HAL-US is 30 mg/L “as ammonia.” To facilitate comparison to the analytical results, we have converted and reported this HAL-US as 24.7 mg/L “as 

nitrogen.”

3

 SRL defined for ammonia as the highest concentration detected in field blanks collected for the Santa Barbara study unit. All detections of ammonia reported 

by the laboratory were greater than the SRL.
44 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Table 10. Major and minor ions, silica, and total dissolved solids (TDS) detected in samples collected for the Santa Barbara study unit, 

January to February 2011, California GAMA Priority Basin Project.

[The five-digit U.S. Geological Survey parameter code below the constituent name is used to uniquely identify a specific constituent or property. Information 

about the analytes given in table 3H. GAMA well identification number: SB, Santa Barbara study unit grid well; SBU, Santa Barbara study unit understanding 

well. Laboratory reporting level, benchmark type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks 

are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. 

Secondary maximum contaminant level benchmarks are listed as SMCL-CA when the SMCL-CA exists, and as SMCL-US when the SMCL-CA does not exist. 

MCL-CA, California Department of Public Health (CDPH) maximum contaminant level; SMCL-CA, CDPH secondary maximum contaminant level. Other 

abbreviations: LT-MDL, long-term method detection level; MRL, minimum reporting level; mg/L, milligrams per liter; SiO2, silicon dioxide; —, not detected; 

*, value above benchmark level; **, value above upper benchmark level]

GAMA well 

identification 

number

Bromide 

(mg/L) 

(71870) 

Calcium 

(mg/L) 

(00915) 

Chloride 

(mg/L) 

(00940) 

Fluoride 

(mg/L) 

(00950) 

Iodide 

(mg/L) 

(71865)

Magnesium 

(mg/L) 

(00925) 

Potassium 

(mg/L) 

(00935) 

Silica 

(as SiO2

) 

(mg/L) 

(00955) 

Sodium 

(mg/L) 

(00930) 

Sulfate 

(mg/L) 

(00945) 

Residue on 

evaporation 

(TDS) 

(mg/L) 

(70300)

Benchmark type na na SMCL-CA MCL-CA na na na na na SMCL-CA SMCL-CA

Benchmark level na na 1

 250 (500) 2 na na na na na 1 250 (500) 1 500 (1,000)

[LT-MDL] or [MRL] [0.010] [0.022] [0.06] [0.04] [0.0010] [0.008] [0.022] [0.029] [0.06] [0.09] [12]

Santa Barbara grid wells (18 wells sampled)

SB-01 0.97 327 239 0.43 0.088 87.3 14.7 39.9 132 **795 **1,930

SB-02 0.25 128 64.3 0.42 0.029 36.7 4.13 33 89.6 *255 *850

SB-03 0.23 158 69.7 0.40 0.020 51.5 2.68 23.9 60.1 *360 *946

SB-04 0.10 95.9 33.3 0.41 0.021 36.7 3.38 18.4 49.5 231 *620

SB-05 0.92 191 *399 0.31 0.005 40.2 1.60 28.2 101 125 **1,150

SB-06 0.32 127 83.4 0.52 0.066 38.6 3.13 36.8 109 *285 *904

SB-07 0.86 175 *344 0.59 0.007 87.3 1.07 21.8 147 *265 **1,280

SB-08 0.11 78.7 38.3 0.26 0.007 25.3 1.33 41.5 53.1 154 *541

SB-09 0.25 41.6 73.6 0.34 0.004 14.2 0.92 53.7 55.4 64.1 344

SB-10 1.00 101 *314 0.55 0.030 39.1 1.78 36 174 134 **1,070

SB-11 0.22 115 81.9 1.05 0.002 32.8 0.88 28 71.0 196 *716

SB-12 0.16 162 122 0.36 0.003 49.5 0.88 26.9 77.9 *301 *960

SB-13 1.17 198 *453 0.73 0.020 76.9 1.55 32.3 133 *261 **1,390

SB-14 0.32 38.7 134 *2.37 0.057 1.49 1.48 14.6 199 26.9 *640

SB-15 0.11 87.0 31.7 0.36 0.022 24.4 1.37 26.7 58.7 111 *524

SB-16 0.37 110 57.3 0.34 0.015 29.5 1.19 22.3 50.3 139 *619

SB-17 0.25 156 108 0.49 0.003 60.1 1.83 21.9 95.0 *303 **1,020

SB-18 0.23 116 104 0.51 0.007 54.6 1.76 21.6 88.7 225 *853

Santa Barbara understanding wells (6 wells sampled)

SBU-01 0.11 153 40.2 0.34 0.012 34.2 2.27 41.4 50.4 *265 *782

SBU-02 5.50 97.5 **1,440 1.47 2.82 26.5 7.43 27.5 813 32.2 **2,640

SBU-03 0.22 101 75.0 0.30 0.089 23.9 1.70 35.1 60.3 37.4 *552

SBU-04 0.05 71.4 20.2 0.30 — 20.4 1.31 36.2 40.2 94.8 425

SBU-05 0.29 96.8 92.9 0.47 0.001 29.8 1.34 38.2 42.0 118 *528

SBU-06 0.35 107 118 0.25 0.021 31.8 1.58 33.8 47.4 155 *622

1

 The SMCL-CA for chloride, sulfate, and TDS have recommended and upper benchmark values. The upper value is shown in parentheses.
Tables 45

Table 11. Arsenic, chromium, and iron species detected in samples collected for the Santa Barbara study unit, January to 

February 2011, California GAMA Priority Basin Project.

[Data in this table analyzed at U.S. Geological Survey (USGS) Trace Metals Laboratory using research methods. Information about the analytes given 

in table 3I. The five-digit USGS parameter code below the constituent name is used to uniquely identify a specific constituent or property. GAMA well 

identification number: SB, Santa Barbara study unit grid well; SBU, Santa Barbara study unit understanding well. Method detection level, benchmark 

type, and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the MCL-US 

and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. Secondary maximum contaminant level 

benchmarks are listed as SMCL-CA when the SMCL-CA exists, and as the SMCL-US when the SMCL-CA does not exist. MCL-US, U.S. Environmental 

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

SMCL-CA, CDPH secondary maximum contaminant level. Other abbreviations: MDL, method detection limit; na, not available; μg/L, micrograms per liter; 

—, not detected; *, greater than the benchmark level]

GAMA well 

identification 

number

Arsenic 

(μg/L) 

(99033) 

Arsenic (III) 

(μg/L) 

(99034)

Chromium 

(μg/L) 

(01030)

Chromium (VI) 

(μg/L) 

(01032)

Iron 

(μg/L) 

(01046)

Iron (II) 

(μg/L) 

(01047) 

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

Benchmark level 10 na 50 na 300 na

[MDL] [0.2] [0.5] [0.1] [0.1] [2] [2]

Santa Barbara grid wells (18 wells sampled)

SB-01 — — 0.2 — *1,310 1,280

SB-02 1.8 1.3 0.1 0.1 *1,300 1,280

SB-03 1.3 0.7 0.2 0.2 293 266

SB-04 0.5 — 0.2 0.2 79 42

SB-05 0.3 — 1.7 1.5 6 —

SB-06 0.2 — 0.3 — 174 171

SB-07 0.2 — 0.8 0.7 120 80

SB-08 0.3 — 0.5 0.3 4 2

SB-09 — — 0.9 0.7 — — 1

SB-10 0.2 — 1.6 0.2 4 —

SB-11 — — 0.3 0.2 4 2

SB-12 — — 2.0 0.2 2 —

SB-13 — — — — 153 104

SB-14 — — — 0.2 *415 360

SB-15 0.8 — 0.7 0.6 22 11

SB-16 0.7 — 0.4 0.4 75 40

SB-17 — — 0.2 0.2 3 —

SB-18 0.3 — 0.4 0.4 7 —

Santa Barbara understanding wells (6 wells sampled)

SBU-01 0.3 — 0.3 0.3 *426 411

SBU-02 1.1 na2 0.9 0.5 4 4

SBU-03 1.3 na2 0.4 0.3 — — 1

SBU-04 0.2 — 0.4 0.2 — — 1

SBU-05 — — 1.4 0.8 — — 1

SBU-06 1.9 0.7 0.3 — 192 185

1

 Iron (II) is not measured if iron (total) is a non-detection.

2

 Values censored by the laboratory due to suspected positive interference during analysis.
46 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Table 12. Results for analyses of stable isotope ratios, tritium activity, and carbon-14 abundance detected in samples collected for the 

Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.

[The five-digit U.S. Geological Survey parameter code below the constituent name is used to uniquely identify a specific constituent or property. Information 

about the analytes given in table 3J. 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. Measured values of tritium less than the sample-specific critical level (ssLC) are reported 

as non-detections (—). GAMA well identification number: SB, Santa Barbara study unit grid well; SBU, Santa Barbara study unit understanding well. 

Benchmark type and benchmark level as of February 4, 2011. Benchmark type: Maximum contaminant level benchmarks are listed as MCL-US when the 

MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the MCL-US or no MCL-US exists. MCL-CA, California Department 

of Public Health (CDPH) maximum contaminant level. Elements: H, hydrogen; O, oxygen; C, carbon. Other abbreviations: CSU, 1-sigma combined standard 

uncertainty; ±, plus or minus; pCi/L, picocuries per liter; na, not available]

GAMA well 

identification 

number

δ2H 

(per mil) 

(82082)

δ18O 

(per mil) 

(82085)

δ13C 

(per mil) 

(82081)

Carbon-14 

(percent modern carbon) 

(49933)

Tritium 

(pCi/L)

(07000)

Benchmark type na na na na MCL-CA

Benchmark level na na na na 20,000

Result ± CSU ssLC

Santa Barbara grid wells (18 wells sampled)

SB-01 –34.0 –5.74 –13.37 46.5 — 0.27

SB-02 –35.2 –5.87 –14.18 77.2 0.4 ± 0.31 0.31

SB-03 –36.4 –5.90 –12.79 82.2 1.64 ± 0.32 0.29

SB-04 –39.0 –6.14 –14.29 69.9 3.38 ± 0.35 0.3

SB-05 –34.9 –5.68 –14.66 82.3 1.37 ± 0.44 0.4

SB-06 –36.3 –5.98 –13.18 43.0 — 0.3

SB-07 –33.9 –5.67 –14.67 83.6 1.26 ± 0.41 na 1

SB-08 –36.8 –6.10 –13.30 69.2 0.75 ± 0.3 0.3

SB-09 –35.2 –5.86 –18.20 86.3 1.31 ± 0.34 0.32

SB-10 –34.9 –5.55 –16.59 87.3 3.89 ± 0.44 0.39

SB-11 –36.0 –5.99 –14.40 96.2 4.59 ± 0.44 0.38

SB-12 –34.3 –5.59 –17.45 108 5.33 ± 0.43 0.34

SB-13 –34.1 –5.44 –15.11 76.4 1.24 ± 0.35 0.33

SB-14 –39.2 –6.21 –15.58 47.9 — 0.34

SB-15 –39.4 –6.30 –13.64 56.6 — 0.3

SB-16 –38.8 –6.23 –13.35 66.5 0.94 ± 0.28 0.27

SB-17 –34.8 –5.50 –14.60 92.4 5.01 ± 0.41 0.36

SB-18 –35.6 –5.66 –14.01 77.6 1.9 ± 0.39 0.35

Santa Barbara understanding wells (6 wells sampled)

SBU-01 –36.5 –6.06 –12.78 71.6 — 0.3

SBU-02 –38.2 –5.79 –14.17 85.4 — na 1

SBU-03 –36.2 –6.06 –16.60 57.4 — na 1

SBU-04 –37.0 –6.25 –15.12 72.7 0.61 ± 0.38 na 1

SBU-05 –36.8 –6.12 –10.44 33.9 — na 1

SBU-06 –37.3 –6.15 –13.81 84.8 1.01 ± 0.35 0.4

1

 Some ssLCs were not reported by the laboratory in time for inclusion in this report. For these results, measured values of tritium less than the 1-sigma 

combined standard uncertainty (SBU-02: 0.41; SBU-03: 0.41; SBU-05: 0.38) were reported as non-detections.
Tables 47

Table 13A. Radon-222 detected in samples collected for the 

Santa Barbara study unit, January to February 2011, California 

GAMA Priority Basin Project.

[The five-digit number in parentheses below the constituent name is the 

U.S. Geological Survey parameter code used to uniquely identify a specific 

constituent or property. Samples from 22 wells were analyzed. Information 

about the analytes are given in table 3J. The reporting levels for radioactive 

constituents are given as sample-specific critical levels (ssLC). GAMA well 

identification number: SB, Santa Barbara study unit grid well; SBU, Santa 

Barbara study unit understanding well. Benchmark type and benchmark 

level as of February 4, 2011. Benchmark type: Maximum contaminant level 

benchmarks are listed as MCL-US when the MCL-US and MCL-CA are 

identical, and as MCL-CA when the MCL-CA is lower than the MCL-US 

or no MCL-US exists. MCL-US, U.S. Environmental Protection Agency 

(USEPA) maximum contaminant level. Other abbreviations: CSU, 1-sigma 

combined standard uncertainty; pCi/L, picocuries per liter; ±, plus or minus]

GAMA well 

identification 

number

Radon-222 

(pCi/L) 

(82303)

Benchmark type Proposed MCL-US

Benchmark level 4,000

 Result ± CSU ssLC

Santa Barbara grid wells (16 wells sampled) 1

SB-01 139 ± 13 12

SB-03 840 ± 49 13

SB-04 274 ± 19 12

SB-05 1,150 ± 66 14

SB-07 860 ± 50 10

SB-08 1,070 ± 60 10

SB-09 1,500 ± 83 12

SB-10 760 ± 44 12

SB-11 1,080 ± 61 11

SB-12 1,990 ± 110 14

SB-13 1,460 ± 82 14

SB-14 520 ± 32 11

SB-15 390 ± 26 14

SB-16 330 ± 22 12

SB-17 1,180 ± 67 14

SB-18 660 ± 39 12

Santa Barbara understanding wells (6 wells sampled)

SBU-01 212 ± 16 12

SBU-02 470 ± 30 14

SBU-03 840 ± 50 14

SBU-04 350 ± 23 12

SBU-05 630 ± 38 12

SBU-06 850 ± 49 12

1

 Sample-collection syringe broke before radon samples from SB-02 and 

SB-06 could be collected.
48 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Table 13B. Gross alpha and gross beta radioactivity detected in samples collected for the Santa Barbara study unit, January to 

February 2011, California GAMA Priority Basin Project.

[The five-digit number in parentheses below the constituent name is the U.S. Geological Survey parameter code used to uniquely identify a specific constituent 

or property. Information about the analytes given in table 3J. The reference nuclide for measurement of gross alpha radioactivity is thorium-230, and the 

reference nuclide for measurement of gross beta radioactivity is cesium-137. The reporting levels for radioactive constituents are given as sample-specific 

critical levels (ssLC). Measured values less than the ssLC are reported as non-detections (—). GAMA well identification number: SB, Santa Barbara study 

unit grid well; SBU, Santa Barbara study unit understanding well. Benchmark type and benchmark level as of February 4, 2011. Benchmark type: Maximum 

contaminant level benchmarks are listed as MCL-US when the MCL-US and MCL-CA are identical, and as MCL-CA when the MCL-CA is lower than the 

MCL-US or no MCL-US exists. MCL-US, U.S. Environmental Protection Agency (USEPA) maximum contaminant level. Other abbreviations: CSU, 1-sigma 

combined standard uncertainty; pCi/L, picocuries per liter; ±, plus or minus]

GAMA well 

identification 

number

Gross alpha radioactivity, 

72-hour count 

(pCi/L) 

(62636)

Gross alpha radioactivity, 

30-day count 

(pCi/L) 

(62639)

Gross beta radioactivity, 

72-hour count 

(pCi/L) 

(62642)

Gross beta radioactivity, 

30-day count 

(pCi/L) 

(62645)

Benchmark type MCL-US MCL-US MCL-CA MCL-CA

Benchmark level 15 15 50 50

Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC Result ± CSU ssLC

Santa Barbara grid wells (18 wells sampled)

SB-01 3.6 ± 2.1 2.6 4 ± 2.4 3.2 15.7 ± 1.6 1.8 14.8 ± 1.2 1.1

SB-02 2.8 ± 1.2 1.4 3.8 ± 1.2 0.95 4.7 ± 0.75 1 4.1 ± 0.5 0.62

SB-03 11.5 ± 2.2 1.3 7.6 ± 1.7 1.2 3.37 ± 0.53 0.75 6.93 ± 0.75 0.86

SB-04 4 ± 1 0.77 1.65 ± 0.82 1 3.64 ± 0.43 0.51 4.52 ± 0.44 0.48

SB-05 1

 1.9 ± 1.1 1.2 — 2 1.48 ± 0.66 1 1.5 ± 0.7 1.1

SB-06 3.1 ± 1.4 1.8 3.9 ± 1.3 1.2 2.93 ± 0.53 0.75 4.15 ± 0.78 1.1

SB-07 5.4 ± 2.3 2.8 — 2.2 1.0 ± 0.6 0.95 3.18 ± 0.72 1

SB-08 2.65 ± 0.85 0.85 0.86 ± 0.51 0.6 1.49 ± 0.51 0.76 2 ± 0.81 1.2

SB-09 1.12 ± 0.51 0.6 — 0.6 1.05 ± 0.42 0.68 1.06 ± 0.43 0.67

SB-10 — 1.8 — 1.7 2.04 ± 0.56 0.85 1.69 ± 0.81 1.2

SB-11 3.0 ± 1.2 1.4 — 1.1 1.28 ± 0.35 0.52 1.15 ± 0.31 0.46

SB-12 2.9 ± 1.3 1.6 1.6 ± 0.96 1.1 1.92 ± 0.51 0.78 1.81 ± 0.48 0.7

SB-13 6 ± 2 2 1.6 ± 1.2 1.5 3.35 ± 0.68 0.95 1.92 ± 0.56 0.85

SB-14 — 1.3 — 1 1.11 ± 0.43 0.67 2.07 ± 0.42 0.6

SB-15 3.03 ± 0.95 0.89 — 0.89 1.43 ± 0.39 0.59 1.72 ± 0.34 0.48

SB-16 4.9 ± 1.2 0.88 — 1.2 1.92 ± 0.37 0.52 2.2 ± 0.41 0.59

SB-17 7.3 ± 1.8 1.5 8 ± 2.2 2.2 1.91 ± 0.61 0.94 4.5 ± 0.7 0.98

SB-18 1

 6.8 ± 1.7 1.6 8.4 ± 1.7 1.1 1 2.66 ± 0.49 0.69 4.23 ± 0.55 0.7

Santa Barbara understanding wells (6 wells sampled)

SBU-01 2.6 ± 1.1 1.2 — 1.1 2.4 ± 0.4 0.55 2.13 ± 0.41 0.57

SBU-02 1

 10.9 ± 4.2 4.72 — 6.39 9.4 ± 1.5 2.1 8.8 ± 1.5 2.1

SBU-03 1

 3.1 ± 1.2 1.5 — 0.94 2.39 ± 0.36 0.49 1.72 ± 0.34 0.48

SBU-04 2.6 ± 0.7 0.64 — 0.87 1.16 ± 0.49 0.75 2.03 ± 0.51 0.75

SBU-05 1.67 ± 0.97 1.3 1.02 ± 0.71 0.93 1.48 ± 0.56 0.86 1.41 ± 0.56 0.85

SBU-06 — 0.85 — 0.97 1.24 ± 0.41 0.63 1.68 ± 0.56 0.82

1

 72-hour holding time exceeded by 4 to 5 days from time of sample collection.
Appendix 49

Appendix 

This appendix includes discussions of the methods used 

to collect and analyze groundwater samples and report the 

resulting water-quality data. These methods were selected to 

obtain representative samples of the groundwater from each 

well and to minimize the potential for contamination of the 

samples or bias in the data. Procedures used to collect and 

assess QC data and the results of the QC assessments also are 

discussed. 

In the Santa Barbara study unit, groundwater samples 

were collected, and QA procedures were implemented by 

using standard and modified USGS protocols from the 

NAWQA Program (Koterba and others, 1995), the NFM (U.S. 

Geological Survey, variously dated), and protocols described 

by Shelton and others (2001) and Wright and others (2005). 

The QA plan followed by the NWQL, the primary laboratory 

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

(2005) and Pirkey and Glodt (1998). 

Sample Collection and Analysis

Wells were pumped continuously to purge at least three 

casing volumes of water from the well prior to sampling 

(Wilde and others, 1999). Wells were sampled using Teflon®

tubing with brass and stainless-steel fittings attached to 

a sampling point (usually a hose-bib fitting) on the well 

discharge pipe as close to the well head as possible. The 

sampling point was located upstream from water-storage 

tanks and upstream from the well-head treatment system (if a 

system existed). If a chlorinating system was attached to the 

well, the chlorinator was shut off, when possible, before the 

well was purged and sampled, in order to clear all chlorine 

out of the system. The absence of free chlorine was verified 

by using a Hach® field test kit. All monitoring wells sampled 

for the Santa Barbara study unit were artesian wells, and 

special monitoring-well sampling equipment was not used. All 

samples were collected outdoors by connecting a 1- to 3-foot 

length of Teflon® tubing to the sampling point (Lane and 

others, 2003). All fittings and lengths of tubing were cleaned 

between samples (Wilde, 2004).

For the field measurements, groundwater was pumped 

through a flow-through chamber that was attached to the 

sampling point and fitted with a multi-probe meter that 

simultaneously measures the field water-quality indicators—

dissolved oxygen, temperature, pH, and specific conductance. 

Field measurements were made in accordance with protocols 

in the NFM (Radtke and others, 2005; Wilde and Radtke, 

2005; Lewis, 2006; Wilde, 2006; Wilde and others, 2006). 

All sensors on the multi-probe meter were calibrated daily. 

Measured dissolved oxygen, temperature, pH, and specificconductance values were recorded at 5-minute (min) intervals, 

and when these values remained stable for a minimum of 

30 min, samples for laboratory analyses then were collected. 

Field measurements and instrument calibrations were 

recorded by hand on field record sheets and electronically 

in the Personal Computer Field Form (PCFF) program. 

Analytical service requests also were managed by PCFF, 

whereas analytical service requests for non-NWQL 

analysis were entered into laboratory-specific spreadsheets. 

Information from PCFF was uploaded directly into NWIS at 

the end of every week of sample collection. 

Prior to sample collection, polyethylene sample bottles 

were pre-rinsed three times using deionized water, and then 

once with native sample water before sample collection. 

Samples requiring acidification were acidified to a pH of 

between 2 and 1 with the appropriate acids using ampoules 

of certified, traceable concentrated acids obtained from the 

NWQL.

Temperature-sensitive samples were stored on ice prior 

to and during daily shipping to the various laboratories. The 

non-temperature-sensitive samples for tritium, stable isotopes 

of hydrogen and oxygen in water, and dissolved noble gases 

were shipped monthly. Temperature-sensitive or time-sensitive 

samples for VOCs, pesticides (including polar pesticides) and 

pesticide degradates, pharmaceutical compounds, perchlorate, 

NDMA, trace elements, nutrients, major and minor ions, 

silica, TDS, laboratory alkalinity, radon-222, and gross alpha 

and gross beta radioactivity were shipped daily whenever 

possible. Samples to be analyzed for arsenic, chromium, and 

iron species were shipped weekly. The temperature-sensitive 

samples for stable isotopes of carbon in dissolved inorganic 

carbon and carbon-14 abundance were stored on ice, archived 

in a laboratory refrigerator, and shipped after all of the 

laboratory alkalinity measurements were received. Isotopes of 

dissolved boron and strontium in water samples were stored at 

room temperature in the office until all groundwater samples 

were collected and results from the trace element analyses 

were obtained; a subset of samples was selected for analyses, 

based on total boron and strontium concentrations. 

Detailed sampling protocols for individual analyses 

and groups of analytes are described in Koterba and others 

(1995), the NFM (Wilde and others, 1999, 2004), and in the 

references for analytical methods listed in table A1; only brief 

descriptions are given here. VOC samples were collected in 

three 40-milliliter (mL) sample vials that were purged with 

three vial volumes of unfiltered groundwater before bottom 

filling to eliminate atmospheric contamination. One to one 

(1:1) hydrochloric acid to water (HCl/H2

O) solution was 

added as a preservative to the VOC samples. Each sample 

to be analyzed for perchlorate was collected in a 125-mL 

polystyrene bottle and then filtered in two or three 20-mL 

aliquots of groundwater through a 0.20-micrometer (μm) poresize Corning® syringe-tip disk filter into a sterilized 125-mL 

bottle. Tritium samples were collected by bottom filling one 

1-liter (L) polyethylene bottle and one 1-L glass bottle with 

unfiltered groundwater, after first overfilling the bottles with 

three volumes of unfiltered groundwater. Samples for analysis 

of stable isotopes of hydrogen and oxygen in water were 
50 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

collected in a 60-mL clear glass bottle filled with unfiltered 

groundwater, sealed with a conical cap, and secured with 

electrical tape to prevent leakage and evaporation.

Samples for analysis of pesticides (including polar 

pesticides), pesticide degradates, and pharmaceutical 

compounds were collected in 1-L baked amber glass bottles. 

These samples were filtered through a 0.7-μm nominal poresize glass fiber filter during collection. NDMA samples were 

collected in 500-mL baked amber glass bottles treated with 

0.05 gram of sodium thiosulfate (Na2S2O3) as a preservative 

and were filtered at Weck Laboratories, Inc., prior to analysis.

Groundwater samples for trace elements, major and 

minor ions, silica, laboratory alkalinity, and TDS analyses 

required filling one 250-mL polyethylene bottle with 

unfiltered groundwater and one 500-mL and one 250-mL 

polyethylene bottle with filtered groundwater (Wilde and 

others, 2004). Filtration was done using a 0.45-μm poresize PALL® unvented capsule filter that was pre-rinsed with 

2 L of deionized water, then rinsed with 1 L of groundwater 

prior to sampling. Each 250-mL filtered sample then was 

preserved with 7.5-Normal (N) nitric acid. Nutrient samples 

were collected by filtering groundwater into 125-mL brown 

polyethylene bottles. Arsenic and iron species samples were 

filtered into 250-mL polyethylene bottles that were covered 

with tape to prevent light exposure, and samples were 

preserved with 6-N hydrochloric acid. Samples to be analyzed 

for isotopes of dissolved boron and strontium in water were 

filtered into 250-mL polyethylene bottles after bottles were 

rinsed with filtered groundwater and secured with electrical 

tape to prevent leakage and evaporation. Samples to be 

analyzed for gross alpha and gross beta particle activities were 

filtered into 1-L polyethylene bottles and acidified with 7.5-N 

nitric acid. Stable isotopes of carbon in dissolved inorganic 

carbon and carbon-14 abundance samples were filtered 

and bottom filled into 500-mL glass bottles that first were 

overfilled with three bottle volumes of filtered groundwater. 

These samples had no headspace and were sealed with conical 

caps to avoid atmospheric contamination. 

Chromium species samples were collected at the well 

head using a 10-mL syringe with an attached 0.45-μm poresize MILLEX®HA disk filter. After the syringe was rinsed 

thoroughly and filled with groundwater, the first 4 mL of water 

were forced through the filter to waste (to condition the filter), 

and the next 2 mL were filtered slowly into a small centrifuge 

vial for analysis of total chromium. Hexavalent chromium 

then was collected by attaching a small cation-exchange 

column to the syringe filter and, after conditioning the column 

with 2 mL of sample water, an additional 2 mL of sample 

water was collected in a second centrifuge vial. Both vials 

were preserved with 10 microliters (μL) of 7.5-N nitric acid 

(Ball and McCleskey, 2003a, b).

For the collection of radon-222 samples, a stainless-steel 

and Teflon® valve assembly was attached to the sampling 

port at the well head (Wilde and others, 2004). The valve 

was closed partially to create back pressure, and a 10-mL 

groundwater sample was taken through a Teflon® septum on 

the valve assembly by using a glass syringe affixed with a 

stainless-steel needle. The sample was then injected into a 

25-mL vial partially filled with a scintillation mixture (mineral 

oil and 1,2,4-trimethylbenzene) and shaken. The vial then was 

placed in an insulated cardboard tube to protect the sample 

during shipping.

Dissolved noble gases were collected in 3⁄8-inch-diameter 

copper tubes using reinforced nylon tubing connected to 

the hose bib at the well head. Groundwater was flushed 

through the tubing to dislodge bubbles before the flow was 

restricted with a back-pressure valve. Clamps on either side 

of the copper tube then were tightened, trapping a sample of 

groundwater for analyses of dissolved noble gases (Weiss, 

1968). 

Field alkalinity was measured in the mobile laboratory 

at the well site. Samples for field alkalinity titrations were 

collected by filtering groundwater into a 500-mL polyethylene 

bottle. Alkalinity was measured on filtered samples by Gran’s 

titration method (Gran, 1952). Titration data were entered 

directly into PCFF, and the concentrations of bicarbonate 

(HCO3

–

) and carbonate (CO3

2–) automatically were calculated 

from the titration data using the advanced speciation method 

(http://or.water.usgs.gov/alk/methods.html) with pK1 = 6.35, 

pK2 = 10.33, and pKW = 14. Concentrations of HCO3

–

 and 

CO3

2– also were calculated from the laboratory alkalinity and 

laboratory pH measurements. 

Nine laboratories performed chemical analyses for 

this study (table A1), although most of the analyses were 

performed at the NWQL or by laboratories contracted by the 

NWQL. The NWQL maintains a rigorous QA program (Pirkey 

and Glodt, 1998; Maloney, 2005). Laboratory QC samples, 

including method blanks, continuing calibration verification 

standards, standard reference samples, reagent spikes, external 

certified reference materials, and external blind proficiency 

samples are analyzed regularly. Method detection limits are 

tested continuously, and laboratory reporting levels updated 

accordingly. The NWQL maintains National Environmental 

Laboratory Accreditation Program (NELAP) and other 

certifications (http://www.nelac-institute.org/accred-labs.

php). The USGS Branch of Quality Systems (BQS) maintains 

independent oversight of QA at the NWQL and laboratories 

contracted by the NWQL. The BQS also runs the National 

Field Quality Assurance Program (NFQA) that includes 

annual testing of all USGS field personnel for proficiency 

in making field water-quality measurements (http://qadata.

cr.usgs.gov/nfqa/). Results for analyses made at the NWQL or 

by laboratories contracted by the NWQL are uploaded directly 

into the USGS NWIS database. Results of analyses made 

at other laboratories are compiled in a project database and 

uploaded from there into NWIS. 
Appendix 51

Data Reporting

The following section gives details for the laboratory 

reporting conventions and the constituents that are determined 

by multiple methods or by multiple laboratories.

Reporting Limits

The USGS NWQL uses different conventions for 

reporting results for organic and inorganic constituents. For 

organic constituents, a laboratory reporting level (LRL) and 

a long-term method detection level (LT-MDL) are used as 

thresholds for reporting analytical results. The LRL is set to 

minimize the reporting of false negatives (not detecting a 

compound when it actually is present in a sample) to less than 

1 percent (Childress and others, 1999). The LRL usually is 

set at two times the LT-MDL. The LT-MDL is derived from 

the standard deviation of at least 24 method detection limit 

(MDL) determinations made over an extended period of time. 

The MDL is the minimum concentration of a substance that 

can be measured and reported with 99-percent confidence that 

the concentration is greater than zero (at the MDL there is 

less than 1 percent chance of a false positive) (Childress and 

others, 1999; U.S. Environmental Protection Agency, 2002). 

Concentrations less than the LT-MDL are reported as nondetections with a dash (–) in the data tables.

The USGS NWQL updates LRL and LT-MDL values 

regularly, and the values listed in this report were in effect 

during the period that analyses were made for groundwater 

samples from the Santa Barbara study unit (January to 

February 2011). 

For organic constituents, concentrations between 

the LRL and the LT-MDL are reported as having a higher 

degree of uncertainty (coded by the letter “E” preceding the 

values in the tables and text). For information-rich methods, 

detections less than the LT-MDL have a high certainty of 

presence, but the precise concentration is uncertain. These 

values are also E-coded. Information-rich methods are 

those that utilize gas chromatography or high-performance 

liquid chromatography (HPLC) with mass spectrometry 

detection, such as those methods used to analyze VOCs 

and pesticides. Compounds are identified by presence of 

characteristic fragmentation patterns in their mass spectra in 

addition to being quantified by measurement of peak areas 

at their associated chromatographic retention times. E-coded 

values also may result from detections outside the range of 

calibration standards, from detections that did not meet all 

laboratory QC criteria, and from samples that were diluted 

prior to analysis (Childress and others, 1999).

For reporting detections of pharmaceutical compounds, 

GAMA uses more conservative reporting limits than are 

used by the NWQL. The MDL for each compound was 

selected as the maximum of up to five LT-MDLs used by 

the laboratory during the time period May 2004 through 

March 2010 (table 3D). Detections reported by the NWQL 

with concentrations less than the selected MDLs are reported 

as less than the MDL and are not considered detections when 

calculating detection frequencies (Fram and Belitz, 2011).

For most inorganic constituents, the LT-MDL is the only 

threshold used by the NWQL for reporting analytical results. 

All non-detections for inorganics constituents are reported 

in the NWIS database as less than the LT-MDL (except for 

non-detections of bromide, which are reported as less than 

the MDL); E-codes are not used to designate results with 

concentrations less than LRLs or LT-MDLs.

Total dissolved solids, perchlorate, and NDMA are 

reported by using minimum reporting levels (MRLs). The 

MRL is the smallest measurable concentration of a constituent 

that may be reliably reported using a given analytical method 

(Timme, 1995). 

Isotopes of hydrogen, oxygen, carbon, boron, and 

strontium are reported using method uncertainties (MUs). The 

MU generally indicates the precision of a particular analytical 

measurement; it gives a range of values wherein the true value 

will be found. 

Results for most constituents are presented using the 

LRL, LT-MDL, MDL, MRL, or MU values provided by the 

analyzing laboratories. Results for some organic and inorganic 

constituents are presented using study reporting levels (SRLs) 

derived from assessment of data from QC samples associated 

with groundwater samples collected as part of the GAMAPBP (see the appendix section titled “Detections in Field 

Blanks and Application of SRLs”).

The reporting limits for radiochemical constituents 

(carbon-14, tritium, radon-222, and gross alpha and gross 

beta radioactivity) are based on sample-specific critical 

levels (ssLC) (McCurdy and others, 2008). The critical level 

is analogous to the LT-MDL used for reporting analytical 

results for organic and non-radioactive inorganic constituents. 

Here, the critical level is defined as the minimum measured 

activity that indicates a positive detection of the radionuclide 

in the sample with less than a 5-percent probability of a false 

positive detection. Sample-specific critical levels are used 

for radiochemical measurements because the critical level is 

sensitive to sample size and sample yield during analytical 

processing and is dependent on instrument background, on 

counting times for the sample and background, and on the 

characteristics of the instrument being used and the nuclide 

being measured. An ssLC is calculated for each sample, and 

the measured activity in the sample is compared to the ssLC

associated with that sample. Measured activities less than the 

ssLC are reported as non-detections with a dash (–) in the data 

tables. 

The analytical uncertainties associated with measurement 

of activities also are sensitive to sample-specific parameters, 

including sample size, sample yield during analytical 

processing, and time elapsed between sample collection and 

various steps in the analytical procedure, as well as parameters 

associated with the instrumentation. Therefore, measured 

activities of radioactive constituents are reported with samplespecific combined standard uncertainties (CSUs). The CSU 

is reported at the 68-percent confidence level (1-sigma). The 
52 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

ssLC was not reported by the laboratory for some tritium 

results, in which case the CSU was used as an estimated 

reporting level.

Notation 

Stable isotopic compositions of oxygen, carbon, boron, 

and hydrogen are reported as relative isotope ratios in units of 

per mil using the standard delta notation (Coplen and others, 

2002):

 i sample

reference

E

R

R = −

















1 1,000x per mil, (1)

where

i is the atomic mass of the heavier isotope of 

the element,

E is the element (H for hydrogen, O for oxygen, 

B for boron, C for carbon),

Rsample is the ratio of the abundance of the heavier 

isotope of the element (2H, 18O, 11B, 13C) to 

the lighter isotope of the element (1H, 16O, 10B, 12C) in the sample, and

Rreference is the ratio of the abundance of the heavier 

isotope of the element to the lighter isotope 

of the element in the reference material.

The reference material for oxygen and hydrogen is 

Vienna Standard Mean Ocean Water (VSMOW), which is 

assigned δ18O and δ2H values of 0 per mil (note that δ2H 

is sometimes written as δD because the common name of 

the heavier isotope of hydrogen, hydrogen-2, is deuterium) 

(Coplen and others, 2002). The reference material for carbon 

is Vienna Pee Dee Belemnite (VPDB), which is assigned a 

δ13C value of 0 per mil (Coplen and others, 2002). Positive 

values indicate enrichment of the heavier isotope, and negative 

values indicate depletion of the heavier isotope, compared to 

the ratios observed in the standard reference material.

The isotopic composition of strontium is presented as the 

abundance of atoms of the heavier isotope (87Sr) to the lighter 

isotope (86Sr) of the element.

Constituents on Multiple Analytical Schedules

Thirteen constituents targeted in this study were 

measured by more than one analytical method or by more 

than one laboratory (table A2). Preferred analytical methods 

generally were selected on the basis of better performance or 

sensitivity for the constituent, or (in some cases) to provide 

consistency with historical data from the same method. Six 

organic constituents (atrazine, deethylatrazine, tebuthiuron, 

caffeine, metalaxyl, and carbaryl; table 3) each were analyzed 

by two analytical methods for the Santa Barbara study unit; 

however, none of the six constituents were detected by either 

method. 

The field water-quality indicators alkalinity, pH, and 

specific conductance were measured in the field and at 

the NWQL (table 4). Field measurements are generally 

preferred because they are considered more representative of 

groundwater conditions by limiting the amount of time for 

reactions in the water and exposure to the atmosphere to occur 

(Hem, 1985). Field values of pH and specific conductance 

were measured at each Santa Barbara well. Due to time 

constraints, field alkalinities were measured at 12 percent of 

the wells in order to confirm that differences between lab and 

field alkalinity values are negligible for the purpose of this 

study. 

For total arsenic, chromium, and iron concentrations, 

the approved method used by the NWQL, Schedule 1948 

(table 3F), is preferred over the research methods used by the 

USGS Trace Metal Laboratory (table 3I).The concentrations 

measured by the USGS Trace Metal Laboratory only are used 

to calculate ratios of redox species for arsenic, chromium, and 

iron. 

For example,

Cr(III)

Cr(VI)

Cr(T) Cr(VI)

Cr(VI) = , - (2)

where 

Cr(T) is the total chromium concentration 

(measured);

Cr(VI) is the concentration of hexavalent chromium 

(measured); and

Cr(III) is the concentration of trivalent chromium 

(calculated). 

Additionally, tritium was measured at two laboratories: 

LLNL and USGS Stable Isotope and Tritium Laboratory 

(SITL), although only tritium data from the SITL were 

available for reporting at the time of this publication. 

Quality-Control Methods and Results

The purpose of QC is to identify which data best 

represent environmental conditions and which may have been 

affected by contamination or bias during sample collection, 

processing, storage, transportation, and (or) laboratory 

analysis. Four types of QC tests were evaluated in this study: 

(1) blank samples were collected to assess positive bias as a 

result of contamination during sample handling or analysis, 

(2) replicate samples were collected to assess variability, 

(3) matrix-spike tests were done to assess positive or negative 

bias, and (4) surrogate compounds were added to samples 

analyzed for organic constituents to assess potential bias of 

laboratory analytical methods. 
Appendix 53

Blanks

The primary purposes of collecting blanks are to evaluate 

the magnitude of potential contamination of samples with 

compounds of interest during sample handling or analysis and 

to identify and mitigate the sources of sample contamination. 

Results from blanks collected for the Santa Barbara study unit 

and for previous GAMA study units were used to establish 

study reporting levels (SRLs) for some constituents detected 

in blanks. SRLs have higher concentrations than the reporting 

levels used by the laboratory. Detections reported by the 

laboratory with concentrations less than SRLs may have 

significant contamination bias. These data were flagged with 

an appropriate remark code (described in subsequent sections).

Blank Collection and Analysis

Blanks were collected using blank water certified by the 

NWQL to contain less than the reporting levels for selected 

constituents investigated in the study (James A. Lewis, 

National Water Quality Laboratory, written commun., 2012). 

Nitrogen-purged, organic-free blank water was used for blanks 

of organic constituents, and inorganic-free blank water was 

used for blanks of other constituents. 

Source-solution blanks are collected at the beginning 

of a study or when using a new lot of blank water to assess 

potential contamination of samples during transport and 

analysis and potential contamination of the certified blank 

water obtained from the NWQL. Source-solution blanks were 

collected in the USGS San Diego Projects Office laboratory by 

pouring blank water directly into sample containers that were 

preserved, stored, shipped, and analyzed in the same manner 

as the groundwater samples. Source-solution blanks were 

analyzed for VOCs, perchlorate, pharmaceutical compounds, 

NDMA, perchlorate, trace elements, major and minor ions, 

silica, and TDS. Three additional source-solution blanks were 

collected at sampling sites for perchlorate analysis.

Field blanks were collected to assess potential 

contamination of samples during collection, processing, 

transport, and analysis. To collect field blanks at the sampling 

sites, blank water was either pumped or poured through the 

sampling equipment (fittings and tubing) used to collect 

groundwater samples, then processed and transported using 

the same protocols used for the groundwater samples. Four 

liters of blank water were pumped or poured through the 

sampling equipment before each field blank was collected. 

Field blanks were analyzed for VOCs, pesticides (including 

polar pesticides) and pesticide degradates, pharmaceutical 

compounds, NDMA, perchlorate, trace elements, nutrients, 

major and minor ions, silica, TDS, and arsenic, chromium, and 

iron species. 

Field or source-solution blanks were not collected for 

gross alpha and gross beta radioactivity or radon because the 

laboratory determines an ssLC value for each sample. The 

ssLC is the minimum measured value that indicates a non-zero 

amount of the radionuclide in the sample, in other words, an 

amount of the radionuclide that is statistically significantly 

greater than the amount in a blank. Blanks were not collected 

for tritium and dissolved noble gases. Tritium and dissolved 

noble gases are in the atmosphere and would dissolve into any 

solution used in collecting a blank, making it impractical to 

collect a blank for these analytes. Isotopic ratios of carbon, 

boron, hydrogen, oxygen, and strontium are an intrinsic 

property of any of these elements; therefore, the concept of a 

blank does not apply to these ratios.

Study Reporting Levels (SRLs)

SRLs for VOCs detected in field blanks collected for 

the first 32 GAMA-PBP study units (May 2004 through 

September 2010) were defined by Fram and others (2012) 

on the basis of assessment of results from field blanks, 

source-solution blanks, laboratory instrument blanks, 

and groundwater samples. Detections of VOCs having 

concentrations less than the SRLs are reported as nondetections in table 5.

SRLs for trace elements detected in field blanks collected 

in the first 20 GAMA-PBP study units (May 2004 through 

January 2008) were defined by Olsen and others (2010) on 

the basis of statistical assessment of results from the field 

blanks. The assessment used order statistics and binomial 

probabilities to construct an upper confidence limit (Hahn 

and Meeker, 1991) for the maximum concentration of 

constituents possibly introduced while groundwater samples 

were collected, handled, transported, and analyzed. Detections 

of trace elements having concentrations less than the SRLs 

are marked with a ≤ symbol preceding the reported value in 

table 8 to indicate that the true value may be less than or equal 

to the reported value (including the possibility of being a 

non-detection).

SRLs for other classes of constituents detected in field 

blanks collected for the Santa Barbara study unit were defined 

as equal to the highest concentration measured in the field 

blanks.

Detections in Field Blanks and Application of SRLs

Table A3 presents a summary of detections in the field 

blanks and the SRLs applied for the Santa Barbara study unit. 

Three field blanks (representing approximately 12 percent of 

the sampled sites) were collected in the Santa Barbara study 

unit. No constituents were detected in the source-solution 

blanks collected during the Santa Barbara study.

VOCs were not detected in the field blanks for the Santa 

Barbara study unit (table A3). Of the 10 VOCs with SRLs 

defined by Fram and others (2012), only two were detected 

in groundwater samples from the Santa Barbara study unit: 

1,2,4-trimethylbenzene and chloroform. All four detections for 

1,2,4-trimethylbenzene had concentrations less than the SRL 

of 0.56 μg/L and were thus reclassified as non-detections in 

the Santa Barbara study unit dataset (table 5). For the GAMAPBP, concentrations of 1,2,4-trimethylbenzene in blanks and 

groundwater samples less than 0.56 μg/L were found to be 
54 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

correlated with the presence of equipment used for collecting 

radon samples in field vehicles (Fram and others, 2012). The 

vials used to collect radon samples contain a scintillation 

cocktail made of mineral oil and 1,2,4-trimethylbenzene. 

Samples for radon analysis were collected at 22 sites in the 

Santa Barbara study unit. 

The SRL of 0.20 μg/L for chloroform was defined by 

Fram and others (2012) for monitoring wells that require 

special sampling equipment. The length and complexity 

of the lines used with the equipment, such as the Grunfos®

submersible pump, are much greater than for the long and 

short lines sampling configurations. However, the monitoring 

wells sampled for the Santa Barbara study unit were artesian 

(groundwater under positive pressure) and were sampled 

with short lines similar to those used for the other 20 wells. 

Therefore, the SRL was not applied to any chloroform 

detections in the Santa Barbara study unit dataset.

The application and concentration of an SRL for each 

trace element were determined primarily by Olsen and others 

(2010) based on a statistical assessment of quality-control 

results from 2004 to 2008. GAMA SRLs from Olsen and 

others (2010) were used for barium, chromium, copper, 

iron, lead, nickel, tungsten, vanadium, and zinc for the Santa 

Barbara study unit (table A3). Of these trace elements, four 

were detected in at least one Santa Barbara field blank: 

copper, iron, lead, and zinc. Field blank detections were at 

concentrations below the SRL for each constituent, with 

the exception of one iron detection (7.2 μg/L) and one lead 

detection (0.87 μg/L). 

For the trace elements cobalt and manganese, the 

concentrations and detection frequencies in field blanks 

collected for the Santa Barbara study unit suggest that the 

dataset of field blanks used by Olsen and others (2010) 

may not be representative of conditions encountered during 

collection of samples in the Santa Barbara study unit. Cobalt 

was detected in all three field blanks at concentrations 

ranging from 0.05 to 0.22 μg/L; manganese was detected at 

concentrations ranging from 0.24 to 0.47 μg/L (table A3). 

SRLs for cobalt and manganese were defined based on these 

results, at 0.22 μg/L and 0.47 μg/L, respectively. Measured 

concentrations in groundwater samples that were less than the 

SRLs were flagged with a ≤ symbol in table 8. 

Olsen and others (2010) also assigned an SRL of 1.6 μg/L 

for aluminum; however, the NWQL has since raised the 

detection level to 1.7 μg/L based on laboratory performance. 

(See the appendix section titled “Other Quality-Control 

Results” for analysis of BQS data for aluminum.) No SRL was 

defined for aluminum for the Santa Barbara study unit.

Ammonia was detected in one field blank at a 

concentration of 0.013 mg/L (table A3). This concentration 

was used as the SRL for ammonia for the Santa Barbara 

study unit dataset. The SRL resulted in the censoring of no 

detections because there were no measured concentrations of 

ammonia less than 0.013 mg/L in the groundwater samples 

(table 9). 

Constituents were not detected in field blanks for 

the following analyte groups: pesticides (including polar 

pesticides) and pesticide degradates; pharmaceutical 

compounds; perchlorate; NDMA; major and minor ions, silica, 

and TDS; and arsenic, chromium, and iron species. 

Replicates

Sequential replicate samples were collected to assess 

the precision of the water-quality data. Estimates of data 

precision are needed to assess whether differences between 

concentrations in samples are because of differences in 

groundwater quality or because of variability that may result 

from collecting, processing, and analyzing the samples. 

Assessment of Replicate Samples

Two methods for measuring variability were needed to 

adequately assess precision over the broad range of measured 

concentrations of most constituents. The variability between 

measured concentrations in the pairs of sequential replicate 

samples was represented by the standard deviation (SD) for 

low concentrations and by relative standard deviation (RSD) 

for high concentrations (Anderson, 1987; Mueller and Titus, 

2005). The RSD is defined as the SD divided by the mean 

concentration for each replicate pair of samples expressed as 

a percentage. The boundary between concentrations for which 

variability is assessed with SD and concentrations for which 

variability is assessed with RSD was defined as five times the 

reporting level (RL) for each constituent. The RL may be an 

LRL, SRL, MDL, or MRL for each constituent. 

Replicate pairs of analyses of all constituents except for 

radiochemical constituents were evaluated as follows: 

• If both values were reported as detections, the SD 

was calculated if the mean concentration was < 5 RL 

for the constituent, or the RSD was calculated if the 

mean concentration was ≥ 5 RL for the constituent. 

Acceptable precision is defined as an SD of less 

than 1⁄2 RL or an RSD of less than 10 percent. For 

comparison, an RSD of 10 percent is equivalent to a 

relative percent difference (RPD) of 14 percent. 

• If both values were reported as non-detections, the 

variability was set to zero by definition. 

• If one value was reported as a non-detection and the 

other value was reported as a detection less than the 

RL, then a value of zero was substituted for the nondetection and the SD was calculated. Substituting zero 

for the non-detection yielded the maximum estimate of 

variability for the replicate pair. 
Appendix 55

• If one value for a sample pair was reported as a nondetection and the other value was reported as a ≤-coded 

value (less than or equal to the SRL), or if both values 

were reported as ≤-coded values (less than or equal to 

the SRL), the SD was not calculated because the values 

may be analytically identical. The ≤ code indicates that 

the value is a maximum potential concentration, and 

that concentration may be low enough to be reported as 

a non-detection. 

• If one value was reported as a non-detection and the 

other value was reported as a detection greater than 

the RL, the variability for the pair was considered 

unacceptable.

Replicate pairs of analyses of radiochemical constituents 

were evaluated using the following equation (McCurdy and 

others, 2008) to calculate the normalized absolute difference, 

NAD:

NAD R R

CSU CSU = −+

| |

( ) , 1 2

1

2

2

2 (3)

where 

R1, R2 are the results for the two samples in the 

replicate pair, and

CSU1, CSU2 are the combined standard uncertainties 

associated with the results.

Values of NAD < 1.65 correspond to a significance levels 

(α) of 5 percent (α = 0.05), indicating differences that are 

acceptably small and not statistically significant.

If results from replicate sample pairs indicate that 

precision is unacceptable for a constituent and no specific 

reason can be identified, then this greater variability must 

be considered when interpreting the data. If measured 

concentrations are slightly greater than a water-quality 

benchmark, then actual concentrations could be slightly less 

than that benchmark. Similarly, if measured concentrations 

are slightly less than a water-quality benchmark, then actual 

concentrations could be slightly greater than a benchmark. 

Also, if a constituent has high variability in replicate sample 

pairs, then a larger difference between concentrations 

measured in two samples is required to conclude that the two 

samples have significantly different concentrations. 

Variability in Replicate Samples

Tables A4A–C summarize the results of replicate 

analyses for constituents detected in groundwater samples 

collected in the Santa Barbara study unit. Replicate analyses 

were made at three sites, representing approximately 

12 percent of all of the samples collected. 

Of the 854 replicate pairs of constituents analyzed, 

198 pairs had a detection in one or both samples of the pair. Of 

these 198 pairs, 8 pairs (simazine, iron, total chromium [three 

pairs], chromium [VI], iron [II], and gross alpha radioactivity 

[30-day count]) were outside the limits for acceptable 

precision. Results for replicate analyses for constituents that 

were not detected in groundwater samples are not reported in 

tables A4A–C. 

All replicate pairs of samples analyzed for VOCs were 

within limits for acceptable precision. One VOC replicate pair 

had non-detections with different LRLs for two constituents 

(carbon disulfide and trans-1,4-dichloro-2-butene) due to 

interference caused by high levels of sulfur in a previous 

sample set at the NWQL.

Replicate pairs of samples were analyzed for 

120 pesticides (including polar pesticides) and pesticide 

degradates and 13 pharmaceutical compounds. All pairs of 

samples analyzed were composed of non-detections with the 

exception of one replicate pair of simazine. The replicate 

pair consisted of a non-detection (<0.006 μg/L) and a value 

above the LRL (0.007 μg/L), yielding variability considered 

unacceptable (table A4A).

Three replicate pairs of samples were analyzed for the 

24 trace elements. Of the 72 replicate pairs, 17 were composed 

of either two values reported as non-detections, a value 

reported as a non-detection and a value reported as less than or 

equal to the SRL, or two values reported as less than or equal 

to the SRL. Of the remaining 55 pairs of constituents, the SD 

value was greater than half of the LT-MDL for iron (10.6 μg/L 

and —) for one replicate pair (table A4B).

Replicate pairs analyzed for nutrients, major ions, TDS, 

and isotope tracers resulted in SD and RSD values within 

acceptable precision. Three replicate sets of samples were 

analyzed for arsenic, chromium, and iron species. Twelve 

pairs were composed of non-detections and (or) were within 

the acceptable range of precision, and 5 pairs (total chromium 

[3 pairs], chromium [VI], and iron [II]) had RSD or SD values 

outside the limits for acceptable precision (table A4B).

Replicate pairs of radioactive constituents were analyzed 

for variability, including one radon pair with a sample volume 

discrepancy caused during sample collection. Most pairs 

yielded statistically similar results (p ≤ 0.05) and were, 

therefore, considered acceptable. The exception was one gross 

alpha radioactivity (30-day count) pair that was considered 

unacceptable (p > 0.05) (table A4C).

Environmental detections were not modified on the basis 

of the replicate analyses.

Matrix Spikes

The addition of a known concentration of a constituent 

(spike) to a replicate environmental sample enables the 

laboratory to determine the effect of the matrix, in this case 

groundwater, on the analytical technique used to measure the 

constituent. The known compounds added in matrix spikes are 

the same as those analyzed in the environmental samples. This 

enables an analysis of matrix interferences on a compoundby-compound basis. For this study, matrix spikes were added 

by the laboratory performing the analysis rather than in 

the field. Low matrix-spike recovery may indicate that the 
56 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

compound might not be detected in some samples if it were 

present at very low concentrations. Low and high matrix-spike 

recoveries may be a potential concern if the concentration of 

a compound in a groundwater sample is close to the healthbased benchmark; a low recovery could result in a falsely 

measured concentration less than the health-based benchmark, 

whereas a high recovery could result in a falsely measured 

concentration greater than the health-based benchmark.

The GAMA-PBP defined the data-quality objective 

range for acceptable median matrix-spike recoveries as 

70 to 130 percent. Only constituents with median matrixspike recoveries outside of this range were flagged as 

having unacceptable recoveries. For some constituents, an 

acceptable range of 70 to 130 percent for median matrix-spike 

recovery was more restrictive than the acceptable control 

limits for laboratory-set spike recoveries. Laboratory-set 

spikes are aliquots of laboratory blank water to which the 

same spike solution used for the matrix spikes has been 

added. One set spike is analyzed with each set of samples. 

Acceptable control limits for set spikes are defined relative 

to the long-term variability in recovery. For example, for 

many NWQL analyses, acceptable set-spike recovery is 

within ± 3 F-pseudosigma of the median recovery for at least 

30 set spikes (Connor and others, 1998). The F-pseudosigma 

is calculated by dividing the fourth-spread (analogous to 

interquartile range) by 1.349; therefore, the smaller the 

F-pseudosigma, the more precise the determinations (Hoaglin, 

1983). 

Matrix-spike tests were performed for VOCs, 

pesticides (including polar pesticides), pesticide degradates, 

pharmaceutical compounds, and NDMA because the analytical 

methods for these constituents may be susceptible to matrix 

interferences. 

Matrix-Spike Recoveries

Tables A5A–E present a summary of matrix-spike 

recoveries for the Santa Barbara study unit. Replicate samples 

for spike additions of organic constituents were collected at 

three sites, representing approximately 12 percent of all the 

wells sampled. 

Groundwater samples were spiked with 85 VOCs to 

calculate matrix-spike recoveries. Median matrix-spike 

recoveries were between 70 and 130 percent for all VOCs, 

except for one constituent detected in groundwater samples: 

dichlorodifluoromethane (CFC-12). This compound had two 

matrix spike recoveries less than 70 percent (table A5A). 

Groundwater samples were spiked with 63 pesticides 

and pesticide degradates to calculate matrix-spike recoveries. 

Twenty compounds had median matrix-spike recoveries less 

than 70 percent, none of which were detected in groundwater 

samples (table A5B). 

Groundwater samples were spiked with 56 polar 

pesticides and degradates to calculate matrix-spike recoveries. 

Ten compounds had median matrix-spike recoveries less than 

70 percent, and 6 had recoveries greater than 130 percent, 

none of which were detected in groundwater samples 

(table A5C). Results for the compounds included in spiking 

solutions for both pesticide schedules are reported for the 

preferred method only (NWQL Schedule 2003, table A5B) and 

were omitted from table A5C. 

Groundwater samples were spiked with 

14 pharmaceutical compounds to calculate matrix-spike 

recoveries. Four compounds had median matrix-spike 

recoveries less than 70 percent, none of which were detected 

in groundwater samples (table A5D). Results for the 

compounds included in spiking solutions of multiple analytical 

schedules are reported for the preferred method only (NWQL 

Schedule 2060, table A5C) and were omitted from table A5D. 

All three matrix-spike recoveries for NDMA were within the 

acceptable range of 70 to 130 percent (table A5D).

Environmental detections were not modified on the basis 

of the matrix-spike recovery analysis. 

Surrogates

Surrogate compounds are added to environmental 

samples in the laboratory prior to analysis to evaluate the 

recovery of similar constituents. Surrogate compounds were 

added in the laboratory to all groundwater and QC samples 

that were analyzed by the NWQL for VOCs, pesticides 

(including polar pesticides), and pesticide degradates. 

Surrogates are used to identify general problems that may arise 

during laboratory sample analysis that could affect the results 

for all compounds in that sample. Potential problems include 

matrix interferences (such as high levels of dissolved organic 

carbon) that produce a positive bias or incomplete laboratory 

recovery (possibly because of improper maintenance and 

calibration of analytical equipment) that produces a negative 

bias. A 70 to 130 percent recovery of surrogates, in general, 

is considered acceptable; values outside this range indicate 

possible problems with the processing and analysis of samples 

(Connor and others, 1998; Sandstrom and others, 2001).

Surrogate Compound Recoveries

Table A6 presents a summary of the surrogate recoveries 

for the Santa Barbara study unit. The table lists the surrogates, 

the analytical schedule for which each surrogate was used, 

the number of analyses for field blanks and environmental 

samples, the number of surrogate recoveries less than 

70 percent, and the number of surrogate recoveries greater 

than 130 percent for the blank and environmental samples. 

Field blanks and environmental samples were considered 

separately to assess whether or not the matrixes present in 

environmental samples affect surrogate recoveries.

Most surrogate recoveries for the field blanks and 

environmental samples were within the acceptable range of 

70 to 130 percent. For VOC analyses, 100 percent of the field 

blank and 99 percent of the environmental sample surrogate 

recoveries were within the acceptable range. For pesticides 

and pesticide degradates, 100 percent of the field blank and 
Appendix 57

98 percent of the environmental sample surrogate recoveries 

were within the acceptable range. For polar pesticides and 

degradates, 89 percent of the blank and 90 percent of the 

environmental sample surrogate recoveries were within the 

acceptable range. For pharmaceutical compounds, 100 percent 

of the blank and 92 percent of the environmental sample 

surrogate recoveries were within the acceptable range 

(table A6). There were no significant differences between 

surrogate recoveries in field blanks and environmental samples 

(Wilcoxon rank-sum test, p < 0.05). 

Environmental detections were not modified on the basis 

of the surrogate recovery analysis.

Other Quality-Control Results

Two other laboratory QC issues arose during the analysis 

of samples collected for the Santa Barbara study unit: the 

effect of holding-time violations on the results of radioactive 

constituent data and the effect of internal laboratory QC tests 

indicating bias on the results of trace element data.

Holding time refers to the time in calendar days from 

sample collection to the analysis of the sample. A holdingtime violation occurs when a sample is analyzed past the 

given holding time for a particular analysis. Analyses for 

some samples in the Santa Barbara study unit were completed 

after the given holding time due to a scheduling error at the 

laboratory or a shipping error. A delay in the analysis at the 

laboratory may result in different measured activities or 

concentrations than what may have been present in the sample. 

NDMA has a holding time of 7 days to minimize the risk 

of the compound degrading prior to analysis. One groundwater 

sample and the associated field blank for NDMA analysis 

(table 3E) exceeded this holding time due to a shipping error. 

NDMA was not detected in this sample, but if the sample had 

been analyzed on time, NDMA may have been detected at 

very low concentrations. 

The gross alpha and beta radioactivity reported result is 

the amount measured in the sample. Radioactive decay occurs 

between the time of sample collection and measurement; 

therefore, gross alpha and gross beta radioactivity can change 

with time. At least one result from the analysis of gross alpha 

and beta radioactivity (72-hour counts) was analyzed past the 

holding time in each of five groundwater and quality-control 

samples. The results for these five samples are footnoted in 

tables 13B or A4C. Gross alpha radioactivity (72-hour) may 

be lower and gross beta radioactivity (72-hour) may be lower 

or higher in samples analyzed past the holding time than 

they would have been if analyzed on time. One of the Santa 

Barbara study unit samples had a gross alpha radioactivity 

result near the benchmark and was analyzed 5 days past the 

collection time. 

Laboratory bias as indicated from internal laboratory 

QC tests is another issue that must be investigated to 

determine whether or not the data are affected. The BQS 

operates independent, external quality-assurance projects 

called the Inorganic Blind Sample Project (IBSP) and Blind 

Blank Program (BBP) to monitor and evaluate the quality 

of results for analyses of trace elements, nutrients, major 

and minor ions, silica, and TDS by the NWQL. The IBSP 

submits standard reference samples consisting of natural 

matrix water samples spiked with reagent chemicals to contain 

known concentrations of the inorganic constituents (Farrar 

and Long, 1997). The IBSP samples are disguised as regular 

environmental samples for submission to the NWQL; the 

BBP samples are disguised as regular blank samples. The 

BQS uses results from the IBSP and BBP samples to evaluate 

potential bias in the results reported by the NWQL on a 

continuous basis. The BQS data are readily available on the 

BQS website, and the BQS issues summaries of the results, 

reporting the amount of bias (if any) observed in the results 

(U.S. Geological Survey, 2011c, d, website at http://bqs.usgs.

gov/ibsp/).

The April 2011 BQS summary, which includes a review 

of data for the time period September 1, 2010, through 

March 31, 2011, was examined. The BQS reported that three 

inorganic constituents showed evidence of bias during this 

period: a positive bias for aluminum in blind blanks, a positive 

bias for zinc in blind non-blanks, and a negative bias for 

uranium. Examination of the results for the IBSP samples for 

these three constituents indicated that the analytical biases 

reported by the BQS were not significant for the data collected 

for the Santa Barbara study unit. 

During the time which samples for the Santa Barbara 

study unit were analyzed (January through March 2011), 1 of 

the 15 blind blanks analyzed (6.7 percent) was measured 

at a concentration greater than the LT-MDL: 2.74 μg/L. 

Additionally, two of the three replicate pairs for aluminum 

collected for the Santa Barbara study unit were re-analyzed by 

the NWQL due to disagreement between the environmental 

and replicate samples. The samples, which initially had 

reported values for aluminum ranging from non-detection to 

22.1 μg/L, were all adjusted by the lab to non-detections upon 

re-analysis.

The BBP and replicate data demonstrated variability 

for aluminum at low concentrations; however, the IBSP data 

indicate that the variability is not significant for this particular 

study. The IBSP non-blank samples for aluminum, analyzed 

January through March 2011, had concentrations ranging 

from 33.8 μg/L to 144 μg/L. The average difference between 

the measured and expected concentrations was –0.5 μg/L 

(standard deviation = 3 μg/L). The maximum concentration 

of aluminum for the Santa Barbara study unit was 5.2 μg/L 

(table 8), and a difference of 0.5 μg/L does not affect 

assessment of whether groundwater samples in the Santa 

Barbara study unit have aluminum concentrations greater 

than or less than the MCL-CA concentration (1,000 μg/L) 

or greater than or less than one-half of the MCL-CA 

concentration. 

The IBSP non-blank blind samples for zinc had 

concentrations ranging from 9 μg/L to 840 μg/L, with positive 

bias demonstrated primarily at the high end due to instruments 

set to achieve lower detection levels. The average difference 
58 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

between the measured and expected concentrations was 

37 μg/L (standard deviation = 36 μg/L), and the average 

relative percent difference between the measured and expected 

concentrations was 7 percent (standard deviation = 5 percent). 

The maximum concentration of zinc in samples for the Santa 

Barbara study unit is 73.7 μg/L, a value less than 1/10 of the 

concentrations showing most bias (800 μg/L or above), and 

much lower than the SMCL-CA for zinc (5,000 μg/L). Thus, 

the estimate of bias from the ISBP samples would not be 

relevant for assessment of whether groundwater samples have 

zinc concentrations greater than or less than the SMCL-CA 

concentration or greater than or less than one-half of the 

SMCL-CA concentration.

The negative bias for uranium demonstrated by IBSP 

samples started in December 2010; however, results were 

within acceptable bias and variability during the time period 

Santa Barbara study unit samples were analyzed. The IBSP 

samples for uranium (January through March 2011) had 

concentrations ranging from 0.28 to 1.4 μg/L. The average 

difference between measured and expected concentrations 

was –0.03 μg/L (standard deviation = 0.04 μg/L), and the 

average relative percent difference between the measured and 

expected concentrations was –4 percent (standard deviation = 

5 percent). However, the maximum concentration of uranium 

in samples from the Santa Barbara study unit was 14.4 μg/L; 

thus, a potential negative bias of 0.6 μg/L, or 4 percent, does 

not affect assessment of whether groundwater samples in 

the Santa Barbara study unit have uranium concentrations 

greater than or less than the MCL-US of 30 μg/L. Moreover, 

the bias observed in the IBSP samples was the highest at 

concentrations close to the LT-MDL and does not imply that 

there is equivalent bias at higher concentrations.
Appendix 59

Table A1. Analytical methods used for the determination of organic and inorganic constituents by the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) and contract laboratories.[Laboratory entity codes in the USGS National Water Information System (NWIS) for laboratories other than the USGS NWQL are given in parentheses after the laboratory names. Abbreviations: UV-VIS, ultraviolet-visible; VOC, volatile organic compound; USEPA, U.S. Environmental Protection Agency; d, delta notation, the ratio of a heavier isotope of an element (iE) to the more 

common lighter isotope of that element, relative to a standard reference material, expressed as per mil; H, hydrogen; O, oxygen; B, boron; Sr, strontium; C, carbon; NRP, National Research Program]

Analyte Analytical method Laboratory and analytical schedule Citation(s)

Water-quality indicators

Field parameters Calibrated field meters and test kits USGS field measurement U.S. Geological Survey, variously dated

Organic constituents

VOCs Purge and trap capillary gas chromatography/

mass spectrometry

NWQL, Schedule 2020 Connor and others, 1998

Pesticides and degradates Solid-phase extraction and gas chromatography/

mass spectrometry

NWQL, Schedule 2003 Zaugg and others, 1995; Lindley and others, 

1996; Sandstrom and others, 2001; Madsen and others, 2003

Polar pesticides and degradates Solid-phase extraction and high-performance 

liquid chromatography (HPLC)/mass spectrometry with selective-ion monitoring

NWQL, Schedule 2060 Furlong and others, 2001

Pharmaceuticals Solid-phase extraction and HPLC/mass 

spectrometry

NWQL, Schedule 2080 Kolpin and others, 2002; Furlong and others, 

2008

Constituents of special interest

Perchlorate Liquid chromatography with mass spectrometry/

mass spectrometry (USEPA Method 331.0)

Weck Laboratories, Inc., City of Industry, 

California, standard operating procedure ORG099.R01

U.S. Environmental Protection Agency, 2005

N-Nitrosodimethylamine (NDMA) Isotopic dilution with gas chromatography 

and chemical-ionization mass spectrometry (USEPA Method 1625 modified)

Weck Laboratories, Inc., City of Industry, 

California, standard operating procedure ORG065.R10

U.S. Environmental Protection Agency, 1989; 

Plomley and others, 1994

Inorganic constituents

Nutrients Alkaline persulfate digestion, Kjedahl digestion NWQL, Schedule 2755 Fishman, 1993; Patton and Kryskalla, 2003Major and minor ions, trace elements Atomic absorption spectrometry, colorimetry, 

ion-exchange chromatography, inductivelycoupled plasma atomic-emission spectrometry and mass spectrometry

NWQL, Schedule 1948 Fishman and Friedman, 1989; Faires, 1993; 

Fishman, 1993; McLain, 1993; Garbarino, 1999; American Public Health Association, 1998; Garbarino and others, 2006

Arsenic, chromium, and iron species Various techniques of ultraviolet visible 

(UV-VIS) spectrophotometry and atomicabsorbance spectroscopy

USGS Trace Metal Laboratory, 

Boulder, Colorado (USGSTMCO)

Stookey, 1970; To and others, 1998; Ball and 

McCleskey, 2003a, b; McCleskey and others, 2003
60 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program Analyte Analytical method Laboratory and analytical schedule Citation(s) Isotopes Stable isotopes of hydrogen (d2H) and oxygen (d18O) of water Gaseous hydrogen and carbon dioxide-water equilibration and stable-isotope mass spectrometry USGS Stable Isotope Laboratory, Reston,

Virginia (USGSSIVA), NWQL 

Schedule 1142

Epstein and Mayeda, 1953; Coplen and others, 

1991; Coplen, 1994

d13C of inorganic carbon dissolved in water and 

carbon-14 abundance

Accelerator mass spectrometry Woods Hole Oceanographic Institution, 

National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS), Woods Hole, Massachusetts (MA-WHAMS), 

NWQL Schedule 2255

Vogel and others, 1987; Donahue and others, 

1990; McNichol and others, 1992; Gagnon and Jones, 1993; McNichol and others, 1994; Schneider and others, 1994

d11B of boron dissolved in water Negative thermal-ionization mass spectrometry USGS NRP Metals Isotope Research Laboratory, 

Menlo Park, California (USGSMICA)

Vengosh and others, 1989; Dwyer and Vengosh, 

2008

87Sr/86Sr of strontium dissolved in water Chemical separations of thermal-ionization mass 

spectrometry

USGS NRP Metals Isotope Research Laboratory, 

Menlo Park, California (USGSMICA)

Bullen and others, 1996

Radioactive constituents and noble gases

Tritium Electrolytic enrichment-liquid scintillation USGS Stable Isotope and Tritium Laboratory, 

Menlo Park, California (USGSH3CA)

Thatcher and others, 1977

Tritium and dissolved noble gases Helium-3 in-growth and mass spectrometry Lawrence Livermore National Laboratory, 

Livermore, California (CA-LLNL)

Moran and others, 2002; Eaton and others, 2004

Radon-222 Liquid scintillation counting NWQL, Schedule 1369 American Society for Testing and Materials, 1998Gross alpha and gross beta radioactivity Alpha and beta activity counting 

(USEPA Method 900.0)

Eberline Analytical Services, 

Richmond, California (CA-EBERL), NWQL Schedule 1792

Krieger and Whittaker, 1980 

Table A1. Analytical methods used for the determination of organic and inorganic constituents by the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) and contract laboratories.—Continued[Laboratory entity codes in the USGS National Water Information System (NWIS) for laboratories other than the USGS NWQL are given in parentheses after the laboratory names. Abbreviations: UV-VIS, ultraviolet-visible; VOC, volatile organic compound; USEPA, U.S. Environmental Protection Agency; d, delta notation, the ratio of a heavier isotope of an element (i

E) to the more 

common lighter isotope of that element, relative to a standard reference material, expressed as per mil; H, hydrogen; O, oxygen; B, boron; Sr, strontium; C, carbon; NRP, National Research Program]
Appendix 61

Table A2. Preferred analytical schedules for selected constituents collected for the Santa Barbara study unit, January to 

February 2011, California GAMA Priority Basin Project.

[Preferred analytical schedules/methods are selected on the basis of the procedure recommended by the U.S. Geological Survey (USGS) National Water Quality 

Laboratory (NWQL) (http://wwwnwql.cr.usgs.gov/dyn.shtml?Preferred_method_selection_procedure). Abbreviations: TML, U.S. Geological Survey Trace 

Metal Laboratory, Boulder, Colorado; LLNL, Lawrence Livermore National Laboratory, Livermore, California; SITL, U.S. Geological Survey Stable Isotope 

and Tritium Laboratory, Reston, Virginia; np, no preference]

Constituent Primary constituent 

classification

Analytical 

schedules

Preferred 

analytical schedule

Results from preferred method reported

Atrazine Pesticide 2003, 2060 2003

Caffeine Wastewater indicator 2060, 2080 2060

Deethylatrazine (2-Chloro-4-isopropylamino-6-amino-s-triazine) Pesticide degradate 2003, 2060 2003

Tebuthiuron Pesticide 2003, 2060 2003

Results from both methods reported

Alkalinity Water-quality indicator field, 1948 field

Arsenic, total Trace element 1948, TML 1948

Carbaryl Pesticide 2003, 2060 np

Chromium, total Trace element 1948, TML 1948

Iron, total Trace element 1948, TML 1948

Metalaxyl Pesticide 2003, 2060 np

pH Water-quality indicator field, 1948 field

Specific conductance Water-quality indicator field, 1948 field

Tritium Inorganic tracer LLNL, SITL np

Table A3. Constituents detected in field blanks and study reporting level (SRL) analyses for the Santa Barbara study unit, January to 

February 2011, California GAMA Priority Basin Project.

[Sources of study reporting level (SRL): Each SRL was selected using one of the three approaches: (1) an analysis of quality-control data from May 2004 

through September 2010 for volatile organic compounds (Fram and others, 2012), (2) an analysis of quality-control data from May 2004 through January 2008 

for trace elements (Olsen and others, 2010), or (3) the maximum concentration observed in the field blanks collected for the Santa Barbara study unit. 

Abbreviations: ≤, less than or equal to; μg/L, micrograms per liter; mg/L, milligrams per liter; —, not detected]

Constituent Number of field blank detections/

total number of field blanks

Concentrations 

detected in field blanks

SRL 

concentration Source of SRL Number of groundwater 

detections ≤-coded

Volatile organic compounds (VOCs) (μg/L)

1,2,4-trimethylbenzene 0/3 — 0.56 Fram and others, 2012 4

Trace elements (μg/L)

Barium 0/3 — 0.36 Olsen and others, 2010 0

Chromium 0/3 — 0.42 Olsen and others, 2010 16

Cobalt 3/3 0.17, 0.05, 0.22 0.22 Santa Barbara field blanks 20

Copper 2/3 1.0, 1.2 1.7 Olsen and others, 2010 7

Iron 1/3 7.2 6.0 Olsen and others, 2010 4

Lead 3/3 0.87, 0.02, 0.06 0.65 Olsen and others, 2010 12

Manganese 3/3 0.31, 0.24, 0.47 0.47 Santa Barbara field blanks 2

Nickel 0/3 — 0.36 Olsen and others, 2010 5

Tungsten 0/3 — 0.11 Olsen and others, 2010 9

Vanadium 0/3 — 0.10 Olsen and others, 2010 2

Zinc 2/5 3.3, 4.2 4.8 Olsen and others, 2010 4

Nutrients (mg/L)

Ammonia, as nitrogen 1/3 0.013 0.013 Santa Barbara field blanks 0
62 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Table A4A. Quality-control summary for replicate analyses of organic constituents and perchlorate detected in samples collected for 

the Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.

[Abbreviations: SD, percent standard deviation; RSD, percent relative standard deviation; ≤, less than or equal to; RL, reporting level; nv, no value in category; 

—, not detected]

Constituent

Number of 

nondetects/ 

number of 

replicates

Number 

of 

≤-coded 

replicates

Number of SDs 

greater than 

1⁄2 RL / number of 

replicates with 

concentration less 

than 5 times the RL

Concentrations of 

replicates with SDs 

greater than 1⁄2 RL 

(environmental, 

replicate) 

Number of RSDs 

greater than 

10 percent/number 

of replicates with 

concentration 

greater than 

5 times the RL

Concentrations 

of replicates with 

RSDs greater than 

10 percent 

(environmental, 

replicate) 

Volatile organic compounds (VOCs) (μg/L)

Chloroform (Trichloromethane) 1/3 nv 0/1 nv 0/1 nv

Bromodichloromethane 2/3 nv 0/1 nv nv nv

1,1,1-Trichloroethane 3/3 nv nv nv nv nv

1,1-Dichloroethane 3/3 nv nv nv nv nv

Perchloroethene 3/3 nv nv nv nv nv

Methyl tert-butyl ether 3/3 nv nv nv nv nv

Trichlorotrifluoroethane (CFC-113) 3/3 nv nv nv nv nv

1,2-Dichloroethane 3/3 nv nv nv nv nv

Dibromomethane 3/3 nv nv nv nv nv

Carbon tetrachloride (tetrachloromethane) 3/3 nv nv nv nv nv

Dichlorodifluoromethane (CFC-12) 3/3 nv nv nv nv nv

Pesticides and pesticide degradates (μg/L)

Simazine 2/3 nv 1/1 —, 0.007 nv nv

Constituent of special interest (μg/L)

Perchlorate 1/3 nv nv nv 0/2 nv
Appendix 63

Table A4B. Quality-control summary for replicate analyses of inorganic constituents, isotope tracers, and radioactivity detected in 

samples collected for the Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.

[Abbreviations: SD, percent standard deviation; RSD, percent relative standard deviation; RL, reporting level; μg/L, micrograms per liter; mg/L, milligrams per 

liter; ≤, less than or equal to; nv, no value in category; — not detected; SiO2, silicon dioxide]

Constituent

Number of 

non-detections 

or ≤-coded 

replicates/

number of 

replicates 

Number of SDs 

greater than 1⁄2 RL/ 

number of replicates 

with concentration 

less than 5 times 

the RL

Concentrations 

of replicates 

with SDs greater 

than 1⁄2 RL 

(environmental, 

replicate) 

Number of RSDs 

greater than 

10 percent/number 

of replicates with 

concentration greater 

than 5 times the RL

Concentrations 

of replicates with 

RSDs greater 

than 10 percent 

(environmental, 

replicate) 

Trace elements (μg/L)

Aluminum 3/3 nv nv nv nv

Antimony 3/3 nv nv nv nv

Arsenic 0/3 nv nv 0/3 nv

Barium 0/3 nv nv 0/3 nv

Beryllium 2/3 0/1 nv nv nv

Boron 0/3 nv nv 0/3 nv

Cadmium 1/3 0/2 nv nv nv

Chromium 0/3 0/3 nv nv nv

Cobalt 0/3 0/3 nv nv nv

Copper 1/3 0/2 nv nv nv

Iron 1/3 1/2 10.6, — nv nv

Lead 0/3 0/3 nv nv nv

Lithium 0/3 nv nv 0/3 nv

Manganese 0/3 0/1 nv 0/2 nv

Molybdenum 0/3 nv nv 0/3 nv

Nickel 0/3 0/3 nv nv nv

Selenium 0/3 nv nv 0/3 nv

Silver 3/3 nv nv nv nv

Strontium 0/3 nv nv 0/3 nv

Thallium 3/3 nv nv nv nv

Tungsten 0/3 0/3 nv nv nv

Uranium 0/3 nv nv 0/3 nv

Vanadium 0/3 nv nv 0/3 nv

Zinc 0/3 0/2 nv 0/1 nv

Nutrients (mg/L)

Ammonia (as nitrogen) 2/3 0/1 nv nv nv

Nitrate plus nitrite (as nitrogen) 0/3 nv nv 0/3 nv

Nitrite (as nitrogen) 1/3 0/1 nv 0/1 nv

Total nitrogen (ammonia + nitrite + nitrate + 

organic nitrogen)

0/3 0/1 nv 0/2 nv

Phosphate, orthophosphate (as phosphorus) 0/3 nv nv 0/3 nv
64 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Constituent

Number of 

non-detections 

or ≤-coded 

replicates/

number of 

replicates 

Number of SDs 

greater than 1⁄2 RL/ 

number of replicates 

with concentration 

less than 5 times 

the RL

Concentrations 

of replicates 

with SDs greater 

than 1⁄2 RL 

(environmental, 

replicate) 

Number of RSDs 

greater than 10 

percent/number 

of replicates with 

concentration greater 

than 5 times the RL

Concentrations 

of replicates with 

RSDs greater 

than 10 percent 

(environmental, 

replicate) 

Major and minor ions, silica, and total dissolved soilds (TDS) (mg/L)

Bromide 0/3 nv nv 0/3 nv

Calcium 0/3 nv nv 0/3 nv

Chloride 0/3 nv nv 0/3 nv

Fluoride 0/3 nv nv 0/3 nv

Iodide 1/3 nv nv 0/2 nv

Magnesium 0/3 nv nv 0/3 nv

Potassium 0/3 nv nv 0/3 nv

Sodium 0/3 nv nv 0/3 nv

Sulfate 0/3 nv nv 0/3 nv

Silica (as SiO2

) 0/3 nv nv 0/3 nv

TDS 0/3 nv nv 0/3 nv

Arsenic, chromium, and iron species (μg/L)

Arsenic (total) 0/3 0/3 nv nv nv

Arsenic (III) 3/3 nv nv nv nv

Chromium (total) 0/3 2/2 0.4, 0.2; 0.4, 0.3 1/1 0.7, 0.4

Chromium (VI) 0/3 1/3 0.6, 0.3 nv nv

Iron (total) 1/3 0/1 nv 0/2 nv

Iron (II) 1

 1/2 nv nv 1/1 11, 13

Isotope tracers 

d2H in water (per mil) 0/3 nv nv 0/3 nv

d18O in water (per mil) 0/3 nv nv 0/3 nv

d13C in dissolved inorganic carbon (per mil) 0/3 nv nv 0/3 nv

Carbon-14 (percent modern) 0/3 nv nv 0/3 nv

1

 One pair was not analyzed for iron (II) because total iron was not detected.

Table A4B. Quality-control summary for replicate analyses of inorganic constituents, isotope tracers, and radioactivity detected in 

samples collected for the Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.—Continued

[Abbreviations: SD, percent standard deviation; RSD, percent relative standard deviation; RL, reporting level; μg/L, micrograms per liter; mg/L, milligrams per 

liter; ≤, less than or equal to; nv, no value in category; — not detected; SiO2, silicon dioxide]
Appendix 65

Table A4C. Quality-control summary for replicate analyses of radioactive constituents detected in samples collected for the Santa 

Barbara study unit, January to February 2011, California GAMA Priority Basin Project.

[For activities of radiochemical constituents, a replicate pair of analyses is defined as acceptable if the normalized absolute difference (NAD) is less than 1.65, 

which corresponds to a significance level of 5 percent (α = 0.05). Abbreviations: >, greater than; pCi/L, picocuries per liter; —, not detected; ±, plus or minus; 

nv, no value in category]

Constituent

Number of pairs 

with NAD 

> 1.65/total number of 

replicate pairs

Activities for replicate pairs 

with NAD > 1.65

(environmental, replicate)

(pCi/L)

Tritium 0/3 nv

Radon-222 1

 0/3 nv

Gross alpha radioactivity, 72-hour count 2

 0/3 nv

Gross alpha radioactivity, 30-day count 1/3 — ± 0.55, 1.51 ± 0.57

Gross beta radioactivity, 72-hour count 2

 0/3 nv

Gross beta radioactivity, 30-day count 0/3 nv

1

 One of the replicate results was affected by a sample volume discrepancy but was within acceptable precision.

2

 Includes a replicate pair counted 4 days after sample collection.

Table A5A. Quality-control summary for matrix-spike recoveries of volatile organic compounds (VOCs) in samples collected for the 

Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.

[Acceptable recovery range is between 70 and 130 percent]

Constituent Number of 

spike samples

Minimum recovery 

(percent)

Maximum recovery 

(percent)

Median recovery 

(percent)

Acetone 3 101 113 106

Acrylonitrile 3 104 107 104

tert-Amyl methyl ether (TAME) 3 88 102 88

Benzene 3 101 105 102

Bromobenzene 3 92 100 92

Bromochloromethane 3 100 106 104

Bromodichloromethane 1 3 92 95 94

Bromoform (Tribromomethane) 3 85 96 91

Bromomethane (Methyl bromide) 3 70 102 84

n-Butylbenzene 3 76 83 77

sec-Butylbenzene 3 88 97 88

tert-Butylbenzene 3 91 105 94

Carbon disulfide 3 62 125 89

Carbon tetrachloride (Tetrachloromethane) 1 3 82 98 98

Chlorobenzene 3 94 99 95

Chloroethane 3 88 107 89

Chloroform (Trichloromethane) 1 3 106 114 109

Chloromethane 3 61 109 74

3-Chloropropene 3 81 97 95

2-Chlorotoluene 3 94 96 94

4-Chlorotoluene 3 90 100 95

Dibromochloromethane 3 85 97 96

1,2-Dibromo-3-chloropropane (DBCP) 3 78 89 86

1,2-Dibromoethane (EDB) 3 100 108 101
66 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Constituent Number of 

spike samples

Minimum recovery 

(percent)

Maximum recovery 

(percent)

Median recovery 

(percent)

Dibromomethane 1 3 97 104 102

1,2-Dichlorobenzene 3 93 101 94

1,3-Dichlorobenzene 3 88 95 89

1,4-Dichlorobenzene 3 91 97 91

trans-1,4-Dichloro-2-butene 3 2

 14 107 71

Dichlorodifluoromethane (CFC-12) 1 3 38 86 41

1,1-Dichloroethane (1,1-DCA) 1 3 105 107 106

1,2-Dichloroethane (1,2-DCA) 1 3 103 110 107

1,1-Dichloroethene (1,1-DCE) 3 93 106 97

cis-1,2-Dichloroethene (cis-1,2-DCE) 3 92 99 93

trans-1,2-Dichloroethene (trans-1,2-DCE) 3 96 100 96

1,2-Dichloropropane 3 98 105 101

1,3-Dichloropropane 3 99 105 103

2,2-Dichloropropane 3 84 87 85

1,1-Dichloropropene 3 87 94 89

cis-1,3-Dichloropropene 3 70 96 92

trans-1,3-Dichloropropene 3 67 89 88

Diethyl ether 3 98 104 102

Diisopropyl ether (DIPE) 3 91 103 92

Ethylbenzene 3 92 99 94

Ethyl tert-butyl ether (ETBE) 3 92 97 94

Ethyl methacrylate 3 90 91 91

o-Ethyl toluene (1-Ethyl-2-methyl benzene) 3 92 104 93

Hexachlorobutadiene 3 76 77 76

Hexachloroethane 3 83 86 86

2-Hexanone (n-Butyl methyl ketone) 3 100 106 102

Iodomethane (Methyl iodide) 3 100 110 102

Isopropylbenzene 3 90 98 90

4-Isopropyl-1-methyl benzene 3 82 91 83

Methyl acrylate 3 94 104 99

Methyl acrylonitrile 3 100 107 101

Methyl tert-butyl ether (MTBE) 1 3 101 105 104

Methyl iso-butyl ketone (MIBK) 3 99 103 102

Methylene chloride (Dichloromethane) 3 104 109 105

Methyl ethyl ketone (2-butanone, MEK) 3 100 108 103

Methyl methacrylate 3 92 93 92

Naphthalene 3 88 96 89

Perchloroethene (PCE, Tetrachloroethene) 1 3 123 139 130

n-Propylbenzene 3 85 95 86

Styrene 3 88 92 92

1,1,1,2-Tetrachloroethane 3 94 97 94

1,1,2,2-Tetrachloroethane 3 96 100 99

Tetrahydrofuran 3 94 104 96

Table A5A. Quality-control summary for matrix-spike recoveries of volatile organic compounds (VOCs) in samples collected for the 

Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.—Continued

[Acceptable recovery range is between 70 and 130 percent]
Appendix 67

Constituent Number of 

spike samples

Minimum recovery 

(percent)

Maximum recovery 

(percent)

Median recovery 

(percent)

1,2,3,4-Tetramethylbenzene 3 85 99 87

1,2,3,5-Tetramethylbenzene 3 89 100 90

Toluene 3 102 107 104

1,2,3-Trichlorobenzene 3 92 93 92

1,2,4-Trichlorobenzene 3 84 88 86

1,1,1-Trichloroethane (1,1,1-TCA) 1 3 98 110 104

1,1,2-Trichloroethane (1,1,2-TCA) 3 97 102 97

Trichloroethene (TCE) 3 92 97 94

Trichlorofluoromethane (CFC-11) 3 102 113 105

1,2,3-Trichloropropane (1,2,3-TCP) 3 99 103 102

Trichlorotrifluoroethane (CFC-113) 1 3 90 98 93

1,2,3-Trimethylbenzene 3 96 105 97

1,2,4-Trimethylbenzene 3 93 101 95

1,3,5-Trimethylbenzene 3 89 97 92

Vinyl bromide (Bromoethene) 3 90 107 94

Vinyl chloride (Chloroethene) 3 81 101 83

m- and p-Xylene 3 93 101 95

o-Xylene 3 92 100 95

1

 Constituents detected in groundwater samples.

2

 Laboratory reported that this sample had a very low recovery for trans-1,4-dichloro-2-butene due to matrix interference from sulfur in a previous sample set.

Table A5A. Quality-control summary for matrix-spike recoveries of volatile organic compounds (VOCs) in samples collected for the 

Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.—Continued

[Acceptable recovery range is between 70 and 130 percent]
68 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Table A5B. Quality-control summary for matrix-spike recoveries of pesticides and pesticide degradates in samples collected for the 

Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.

[Acceptable recovery range is between 70 and 130 percent]

Constituent Number of spike 

samples

Minimum recovery 

(percent)

Maximum recovery 

(percent)

Median recovery 

(percent)

Acetochlor 3 77 91 87

Alachlor 3 79 93 90

Atrazine 3 89 105 100

Azinphos-methyl 3 70 94 86

Azinphos-methyl oxon 3 66 76 76

Benfluralin 3 54 67 63

Carbaryl 3 96 114 97

2-Chloro-2,6-diethylacetanilide 3 79 95 91

4-Chloro-2-methylphenol 3 66 98 89

Chlorpyrifos 3 76 88 80

Chlorpyrifos oxon 3 16 50 24

Cyfluthrin 3 43 49 48

Cypermethrin 3 38 44 43

Dacthal (DCPA) 3 93 106 106

Deethylatrazine (2-Chloro-4-isopropylamino-6-amino-s-triazine) 3 93 118 95

Desulfinylfipronil 3 80 99 97

Desulfinylfipronil amide 3 66 84 76

Diazinon 3 87 97 94

3,4-Dichloroaniline 3 79 94 83

Dichlorvos 3 13 52 30

Dicrotophos 3 23 28 27

Dieldrin 3 71 93 77

2,6-Diethylaniline 3 92 97 96

Dimethoate 3 48 73 58

Ethion 3 39 67 62

Ethion monoxon 3 64 88 77

2-Ethyl-6-methylaniline 3 91 94 94

Fenamiphos 3 83 92 87

Fenamiphos sulfone 3 78 88 78

Fenamiphos sulfoxide 3 18 28 21

Fipronil 3 76 99 85

Fipronil sulfide 3 80 82 80

Fipronil sulfone 3 51 72 68

Fonofos 3 68 86 84

Hexazinone 3 45 49 47

Iprodione 3 65 72 67

Isofenphos 3 73 81 81

Malaoxon 3 62 87 83

Malathion 3 74 91 79

Metalaxyl 3 91 103 93

Methidathion 3 63 84 82

Metolachlor 3 78 88 83

Metribuzin 3 72 100 85
Appendix 69

Constituent Number of spike 

samples

Minimum recovery 

(percent)

Maximum recovery 

(percent)

Median recovery 

(percent)

Myclobutanil 3 70 84 72

1-Naphthol 3 33 75 47

Paraoxon-methyl 3 50 76 68

Parathion-methyl 3 84 99 93

Pendimethalin 3 83 108 85

cis-Permethrin 3 37 49 47

Phorate 3 57 70 66

Phorate oxon 3 71 92 73

Phosmet 3 20 33 28

Phosmet oxon 3 15 39 33

Prometon 3 79 96 88

Prometryn 3 76 94 88

Pronamide (Propyzamide) 3 61 96 88

Simazine 1 3 80 92 87

Tebuthiuron 3 116 148 117

Terbufos 3 53 78 69

Terbufos oxon sulfone 3 48 75 74

Terbuthylazine 3 87 102 100

Tribufos 3 28 44 43

Trifluralin 3 62 75 73

1

 Constituent detected in groundwater samples.

Table A5B. Quality-control summary for matrix-spike recoveries of pesticides and pesticide degradates in samples collected for the 

Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project.—Continued

[Acceptable recovery range is between 70 and 130 percent]
70 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program

Constituent

Number of 

spike 

samples

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Acifluorfen 3 49 125 58

Aldicarb 3 62 105 63

Aldicarb sulfone 3 87 108 98

Aldicarb sulfoxide 3 103 114 103

Atrazine 3 1

 na 1 na 1 na

Bendiocarb 3 100 129 104

Benomyl 3 76 119 86

Bensulfuron-methyl 3 119 172 127

Bentazon 3 56 66 63

Bromacil 3 102 200 124

Bromoxynil 3 25 42 36

Caffeine 3 101 147 121

Carbaryl 3 114 161 119

Carbofuran 3 117 158 122

Chloramben, methyl ester 3 77 121 97

Chlorimuron-ethyl 3 120 217 155

3-(4-Chlorophenyl)-1-

methyl urea 

3 69 148 105

Clopyralid 3 17 82 69

Cycloate 3 73 87 86

2,4-D 3 62 74 70

2,4-D methyl ester none 2 na na na

2,4-D plus 2,4-D methyl 

ester

3 62 74 70

2,4-DB 

(4-(2,4-Dichlorophenoxy)

butyric acid)

3 55 62 61

DCPA (Dacthal) monoacid 3 75 88 86

Deethylatrazine (2-Chloro4-isopropylamino-6-

amino-s-triazine) 

3 1

 na 1 na 1 na

Deisopropyl atrazine 

(2-Chloro-6-ethylamino4-amino-s-triazine) 

3 49 94 84

Dicamba 3 58 76 63

Dichlorprop 3 71 87 81

Dinoseb (Dinitrobutyl 

phenol) 

3 27 55 34

Diphenamid 3 113 139 114

Constituent

Number of 

spike 

samples

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Diuron 3 112 131 119

Fenuron 3 102 129 105

Flumetsulam 3 115 315 124

Fluometuron 3 111 154 114

Hydroxyatrazine 

(2-Hydroxy-4-

isopropylamino-6-

ethylamino-s-triazine)

3 109 149 120

3-Hydroxycarbofuran 3 108 162 109

Imazaquin 3 147 273 165

Imazethapyr 3 133 277 136

Imidacloprid 3 120 268 123

Linuron 3 112 126 117

MCPA (2-Methyl-4-

chlorophenoxyacetic 

acid) 

3 64 73 72

MCPB (4-(2-Methyl-4-

chlorophenoxy)butyric 

acid)

3 54 61 58

Metalaxyl 3 107 135 111

Methiocarb 3 112 146 121

Methomyl 3 108 122 121

Metsulfuron methyl 3 85 192 90

Neburon 3 98 135 114

Nicosulfuron 3 139 204 170

Norflurazon 3 118 161 126

Oryzalin 3 85 101 89

Oxamyl 3 111 122 114

Picloram 3 31 105 53

Propham 3 102 111 108

Propiconazole 3 96 131 112

Propoxur 3 117 147 118

Siduron 3 123 170 142

Sulfometuron-methyl 3 134 194 147

Tebuthiuron 3 1

 na 1 na 1 na

Terbacil 3 108 186 125

Triclopyr 3 80 85 85

Table A5C. Quality-control summary for matrix-spike recoveries of polar pesticides and degradates in samples collected for the Santa 

Barbara study unit, January to February 2011, California GAMA Priority Basin Project.

[Acceptable recovery range is between 70 and 130 percent. Abbreviations: na, not available]

1

 See table A5B for atrazine, deethylatrazine, and tebuthurion matrix-spike recoveries from the preferred method.

2

 2,4-D methyl ester was not included in the spiking solution.
Appendix 71

Table A5D. Quality-control summary for matrix-spike recoveries 

of pharmaceutical compounds and N-nitrosodimethylamine 

(NDMA) in samples collected for the Santa Barbara study unit, 

January to February 2011, California GAMA Priority Basin Project.

[Acceptable recovery range is between 70 and 130 percent. 

Abbreviations: na, not available]

Constituent

Number of 

spike 

samples

Minimum 

recovery 

(percent)

Maximum 

recovery 

(percent)

Median 

recovery 

(percent)

Acetaminophen 3 41 122 109

Albuterol 3 34 82 57

Caffeine 3 1

 na 1 na 1 na

Carbamazapine 3 81 107 89

Codeine 3 76 110 94

Cotinine 3 79 94 93

Dehydronifedipine 3 68 97 91

Diltiazem 3 14 32 23

1,7-Dimethylxanthine 3 81 108 94

Diphenydramine 3 47 75 73

Sulfamethoxazole 3 29 44 32

Thiabendazole 3 31 91 86

Trimethoprim 3 78 111 100

Warfarin 3 38 50 46

N-Nitrosodimethylamine 

(NDMA)

3 92 104 95

1

 See table A5C for caffeine matrix-spike recoveries from the preferred 

method. 
72 Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program Table A6. Quality-control summary for surrogate recoveries of volatile organic compounds (VOCs), pesticides and pesticide degradates, polar pesticides and degradates, and pharmaceutical compounds in samples collected for the Santa Barbara study unit, January to February 2011, California GAMA Priority Basin Project. Surrogate Analytical schedule Constitutent or constituent class analyzed Surrogate information for field blanks Surrogate information for environmental samples Number of analyses Median recovery (percent) Number of surrogate recoveries less than 70 percent Number of surrogate recoveries greater than 130 percent Number of analyses Median recovery (percent) Number of surrogate recoveries less than 70 percent Number of surrogate recoveries greater than 130 percent 1-Bromo-4-fluorobenzene 2020 VOC 3 89 0 0 24 89 0 0 1,2-Dichloroethane-d4 2020 VOC 3 118 0 0 24 123 0 1 Toluene-d8 2020 VOC 3 95 0 0 24 94 0 0 Diazinon-d10 2003 Pesticide 3 88 0 0 24 80 1 0 α-HCH-d6 2003 Pesticide 3 87 0 0 24 84 0 0 2,4,5-T (2,4,5-trichlorophenoxyacetic acid) 2060 Polar Pesticide 3 89 0 0 24 84 0 0 Barban 2060 Polar Pesticide 3 128 0 1 24 110 0 4 Caffeine-13C 2060 Polar Pesticide 3 113 0 0 24 111 1 2 Ethyl nicotinate-d4 2080 Pharmaceutical compound 3 94 0 0 24 88 1 0 Carbamazapine-d4 2080 Pharmaceutical compound 3 109 0 0 24 100 2 1
Appendix 73

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Davis and others—Groundwater-Quality Data in the Santa Barbara Study Unit, 2011: Results from the California GAMA Program—Data Series 742