NEVADA

CALIFORNIA

Pyramid

Lake

Donner Lake

Washoe Lake

Lake Tahoe

Truc kee River

Tru ckee River

80

80

39°

39°30'

120°

119°30'

40°

Wadsworth

Sparks Reno

Truckee

Tahoe

City

South

Lake

Tahoe

0 5 10 20 Miles

0 5 10 20 Kilometers

EXPLANATION

Approximate location

 of Chalk Bluff 

 Treatment Plant

Urban

Agriculture

Forest

Water

Rangeland

Barren

Wetlands

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2009–3100

September 2009

Prepared as part of the National Water-Quality Assessment Program, Source Water-Quality Assessment

Organic Compounds in Truckee River Water Used for 

Public Supply near Reno, Nevada, 2002–05

Printed on recycled paper

Organic compounds studied in this U.S. Geological Survey (USGS) assessment generally are man-made, including, in part, pesticides, solvents, 

gasoline hydrocarbons, personal care and domestic-use products, and refrigerants and propellants. Of 258 compounds measured, 28 were 

detected in at least 1 source water sample collected approximately monthly during 2002–05 at the intake of the Chalk Bluff Treatment Plant, 

on the Truckee River upstream of Reno, Nevada. The diversity of compounds detected indicate various sources and uses (including wastewater 

discharge, industrial, agricultural, domestic, and others) and different pathways (including point sources from treated wastewater outfalls 

upstream of the sampling location, overland runoff, and groundwater discharge) to drinking-water supply intakes. Three compounds were 

detected in more than 20 percent of the source-water intake samples at low concentrations (less than 0.1 microgram per liter), including 

caffeine, p-cresol (a wood preservative), and toluene (a gasoline hydrocarbon). Sixteen of the 28 compounds detected in source water also were 

detected in finished water (after treatment, but prior to distribution; 2004–05). Additionally, two disinfection by-products not detected in source 

water, bromodichloromethane and dibromochloromethane, were detected in all finished water samples. Two detected compounds, cholesterol 

and 3-beta-coprostanol, are among five naturally occurring biochemicals analyzed in this study. Concentrations for all detected compounds in 

source and finished water generally were less than 0.1 microgram per liter and always less than human-health benchmarks, which are available 

for about one-half of the compounds. Seven compounds (toluene, chloroform, bromodichloromethane, dibromodichloromethane, bisphenol A, 

cholesterol, and 3-beta-coprostanol) were measured at concentrations greater than 0.1 microgram per liter. On the basis of this screening-level 

assessment, adverse effects to human health are expected to be negligible (subject to limitations of available human-health benchmarks).

Figure 1. About 1,047 

square miles of the 

Truckee River basin 

are upstream of the 

intake of the community 

water system that 

serves the Reno/Sparks 

metropolitan area. The 

area includes large 

forested areas (45 

percent), rangeland 

(about 29 percent), and 

urban areas (about 5 

percent), all of which 

potentially can affect 

source-water quality. 

About 83 million gallons 

of water per day are 

taken directly from the 

Truckee River at the 

community water system 

to serve water needs of 

about 300,000 people. 

(http://www.tmh2o.com/

water_system, accessed 

September 2, 2009).

Introduction

An investigation by the National WaterQuality Assessment (NAWQA) Program of 

the USGS characterizes the occurrence of 258 

organic compounds in source water (defined 

as stream water collected at a surface-water 

intake prior to water treatment) and finished 

water (defined as water that has passed 

through treatment processes but prior to 

distribution) at the Truckee Meadows Water 

Authority (TMWA) Chalk Bluff Treatment 

Plant. This water treatment plant is one of 

several community water systems that use 

the Truckee River as its sole source of water 

supply upstream of Reno, Nevada (fig. 1). 

The Truckee River flows from alpine Lake 

Tahoe (altitude about 6,200 ft) for 116 mi 

until it discharges into Pyramid Lake (altitude 

about 3,800 ft), a desert terminus lake. The 

Sierra Pacific Railroad and Interstate 80 

run parallel to the Truckee River throughout 

much of the study area (fig. 1); both provide 

potential sources of contamination to the 

Truckee River. Samples were collected 

approximately monthly from the Truckee 

River during 2002–05 using USGS collection 

methods (USGS, 1997–2006), and included 

25 source water (2002–05; some analyses 

are for only 24 samples) and 8 finished water 

(2004–05) samples. Samples were collected 

during high winter-spring flows (maximum 

mean daily flow of 1,340 cubic feet per

second during the study period; Truckee 

River near Mogul stream-gaging site) and 
What “Detections” May Mean to Human Health

The analytical methods used in this study have low detection levels—

typically 100 to 1,000 times lower than State and Federal standards 

and guidelines for protecting water quality. Detections, therefore, do 

not necessarily indicate a concern to human health but rather help to 

identify the environmental presence of a wide variety of chemicals not 

commonly monitored in water resources and to track changes in their 

occurrence and concentrations over time. These findings complement 

ongoing drinking-water monitoring required by Federal, State, and 

local programs, which focus primarily on post-treatment compliance 

monitoring of contaminants regulated by USEPA in drinking water. 

Many of the compounds analyzed by USGS are not included in 

other source- and finished-water monitoring programs such as the 

Unregulated Contaminant Monitoring Regulation (U.S. Environmental 

Protection Agency, 2007b) and the U.S. Department of Agriculture’s 

Pesticide Data Program (U.S. Department of Agriculture, 2008).

low summer-autumn flows (minimum mean daily flow of 30 cubic 

feet per second during the study period; Truckee River near Mogul 

stream-gaging site). Storm events were not specifically targeted during 

this study. The samples were analyzed by the USGS National Water 

Quality Laboratory for pesticides and selected pesticide degradates, 

solvents, gasoline hydrocarbons, disinfection by-products, personal 

care and domestic-use products, refrigerants and propellants, and 

other compounds. These data are stored in the USGS National Water 

Information System (NWIS). Community water systems are required 

to monitor finished water for compounds regulated under the Safe 

Drinking Water Act. Most compounds included in this study are not 

regulated under U.S. Environmental Protection Agency (USEPA) 

Federal drinking-water standards (U.S. Environmental Protection 

Agency, 2007a). The Truckee River study is part of an ongoing 

NAWQA investigation of community water systems across the United 

States. Additional detailed information and references on the sampling 

design; methodology, specific compounds monitored, and the national 

study are described by Carter and others (2007). Further USGS 

information on water quality in the Truckee River basin is available in 

a previous NAWQA study (Bevans and others, 1998).

Occurrence of Organic Compounds in Source Water

Twenty-eight of the 258 compounds analyzed for this study were detected 

in at least 1 source-water sample. These compounds represent many 

different sources and uses and include pesticides, gasoline hydrocarbons, 

personal care products, solvents, and other sources and uses. Three 

compounds were detected in more than 20 percent of the samples: 

caffeine, p-cresol (a wood preservative), and toluene (a gasoline 

hydrocarbon) at concentrations less than 0.1 microgram per liter (μg/L).

Recent advances in laboratory analytical methods have given 

scientists the tools to detect a wide variety of contaminants in the 

environment at low concentrations—often 100 to 1,000 times lower 

than drinking-water standards (see inset “What ‘Detections’ May 

Mean to Human Health”). Twenty-five source-water samples were 

collected and analyzed for 258 compounds, of which, 28 (11 percent) 

were detected in at least one sample in this study (table 1). Overall, 

the compounds detected most frequently in water from the Truckee 

River generally were among those most commonly detected in ambient 

stream water across the Nation (Kingsbury and others, 2008). Although 

28 compounds were detected in source water samples, most of these 

compounds were at concentrations of less than 0.1 μg/L. For all sourcewater sampled for this study, 230 compounds (89 percent) were not 

detected in any source-water. 

Three compounds were detected in more than 20 percent of 

the source-water samples: caffeine, p-cresol, and toluene. These 

compounds are used in domestic use products, wood preservatives, and 

gasoline hydrocarbons, in urban and residential areas in the Truckee 

River basin and across the Nation (Bevans and others, 1998; Kingsbury 

and others, 2008). Their occurrence likely is attributed to runoff from 

the I-80 corridor, which includes a railroad as well as heavy traffic. The 

close proximity of railroad tracks and I-80 along the Truckee River 

for many miles upstream of the Chalk Bluff intake makes creosote 

treated railroad ties and treated posts for guardrails a likely source 

of p-cresol and automobile, truck, and train traffic a likely source of 

toluene. Kingsbury and others (2008) identified similar sources for 

these compounds, but their study also included groundwater discharge 

and (or) treated wastewater discharge from upstream municipalities as 

other potential sources of these compounds, particularly for caffeine. 

Comparisons Between Source Water and Finished Water

More than one-half of compounds detected in source water also were 

detected in finished water, and generally at similar concentrations (except 

for disinfection by-products), typically less than 0.1 micrograms per liter.

Comparisons between source water and finished water are not 

intended to characterize treatment efficacy, but to provide a preliminary 

indication of the potential importance of compounds found in source 

water to the quality of finished water prior to distribution (see inset 

“Finished Water Sampling, Water Treatment, and Significance of 

Comparisons to Source Water”). 

Sixteen of the 28 (57 percent) compounds were detected in both 

source and finished waters (table 1), and often at similar low-level 

concentrations. Eight gasoline hydrocarbons were detected in source 

and finished waters (table 1). Three of the six (50 percent) personal care 

and domestic use products and two of the four (50 percent) disinfection 

by-products were detected in source and finished waters (table 1). 

Toluene was detected in 10 of the 25 (40 percent) source-water samples 

and six of the eight (75 percent) finished-water samples, although 

concentrations of toluene in source-water samples were all less than 0.1 

μg/L and only one finished water sample had concentrations of toluene 

greater than 0.1 μg/L (table 2; fig. 2).

Twelve of 28 compounds were detected only in source water. 

These include all four of the herbicide and herbicide degradates, both 

of the plant- or animal-derived biochemicals, the wood preservative 

compound, which was present in one-third of the source-water 

samples, three of the personal care and domestic use products, and one 

organic synthesis compound (table 1). All four herbicide and herbicide 

degradate compounds were detected between December 2002 and 

March 2003, although finished water sampling did not begin until 

August 2004, so it is not known if these compounds also would have 

been detected in the finished water. Processes affecting the occurrence 

of the plant- and animal-derived biochemicals are not well understood. 

The wood preservative compound (p-cresol) may be removed during the 

water treatment process. 

Two compounds, disinfection by-products (bromodichloromethane 

and dibromochloromethane; tables 1 and 2), were detected only in 

finished water. The presence of disinfection by-products in finished 

water is well documented, understood, and regulated, and is an expected 

outcome of drinking-water disinfection (Krasner and others, 2006).
Finished Water Sampling, Water Treatment, and Significance of 

Comparisons to Source Water

The Chalk Bluff Treatment Plant, operated by TMWA, uses conventional 

water treatment: coagulation/flocculation using aluminum sulfate; sedimentation; 

filtration through anthracite and sand; and disinfection with chlorine and chloramine. 

Powdered activated carbon is used occasionally to treat for taste and odor issues 

during summer months. Finished-water samples were collected at the Chalk Bluff 

Treatment Plant from August 2004 to January 2005. These samples were collected 

approximately 4 to 6 hours after collection of source-water samples to account for 

retention time of the water in the treatment plant (B. Hauk, Chalk Bluff Treatment 

Plant, oral commun., 2004). Some differences between source- and finished-water 

quality might be attributable to changes in source-water quality not represented by 

the finished-water samples because of sample timing and variations in retention 

time, and potential analytic variability associated with low concentrations at or 

near laboratory reporting levels (Kingsbury and others, 2008). Some compounds 

detected in source water possibly were transformed during the treatment process into 

compounds that were not monitored as part of this study.

The study sampling design and resulting comparisons are not intended to 

characterize treatment efficacy, but to provide a preliminary indication of the 

potential importance of compounds detected in source water to the quality of 

finished water prior to distribution. Generally, the type of treatment used by the 

Chalk Bluff Treatment Plant is not specifically designed to remove most of the 

organic compounds monitored in this study.

A Closer Look at Gasoline Hydrocarbons and 

Personal Care and Domestic Use Products 

Detections and concentrations of commonly used 

gasoline hydrocarbons are relatively similar in source 

and finished water. Occurrence and concentrations 

of hydrocarbon compounds differ compound by 

compound, depending on chemical properties, use, and 

hydrologic pathways.

Eight paired samples (source and finished water) 

were collected as part of this study from August 2004 

to January 2005. Gasoline hydrocarbons were detected 

in five source-water samples and three finishedwater samples. Gasoline hydrocarbons are organic 

compounds that are highly volatile, contain only carbon 

and hydrogen atoms, and are common ingredients in 

gasoline and other petroleum products. Benzene, toluene, 

ethylbenzene, and xylene (BTEX) compounds are among 

those present in the highest proportions in gasoline 

(Carter and others, 2007). These compounds may enter 

surface waters from contaminated groundwater, runoff 

from roads and parking lots, and directly from watercraft. 

During sampling by USGS personnel, a petroleum sheen 

Herbicides and herbicide degradates

Atrazine

Dacthal

Deethyl atrazine (DEA)

Diuron

Plant- or animal-derived biochemicals

Cholesterol

3-beta-coprostanol

Personal care and domestic use products

Caffeine

Camphor

HHCB (Hexahydrohexamethylcyclopentabenzopyran)

d-Limonene

Menthol

Methyl salicylate

Manufacturing additives

Bisphenol A

Tris(2-chloroethyl)phosphate

Wood preservative

p-Cresol

Gasoline hydrocarbons and oxygenates

Benzene

Ethylbenzene

Naphthalene

o-Xylene

Styrene

Toluene

m- and p-Xylene

1,2,4- Trimethylbenzene

Solvents

Methylene chloride

Disinfection by-products

Bromoform

Chloroform

Bromodichloromethane

Dibromochloromethane

Fumigant-related compound

1,4-Dichlorobenzene

Organic synthesis compounds

Carbazol

Table 1. A total of 30 of 258 organic compounds were detected in source water and (or) finished 

water samples, near Reno, Nevada, 2002–05. Twenty-eight compounds were detected in source water, 

and 16 of the 28 compounds also were detected in finished water. Two compounds were detected only 

in finished water samples. The diversity of compounds indicate various uses—including industrial, 

agricultural, and domestic—and different pathways—including treated wastewater outfalls upstream 

of the sampling location, overland runoff, and groundwater discharge—of the compounds entering 

drinking-water supplies.

[Black text indicates compounds detected in source and finished water; orange text indicates compounds detected only in

source water; blue text indicates compounds detected only in finished water; italics indicates pesticide degradates]
SOURCE-WATER CONCENTRATION, IN MICROGRAMS PER LITER

0.001

0.01

0.1

1

0.001 0.01 0.1 1

FINISHED-W

ATER CONCENTRATION,

IN MICROGRA

MS PER LITER

1:1 Ratio

Benzene 1,4-Dichlorobenzene,

HHCB, o-Xylene

Methyl salicylate,

caffeine

Napthalene

p-Cresol

3-beta-coprostanol,

cholesterol

Toluene

Camphor

Other detected compounds

Figure 2. Nine of the 16 compounds detected in source water also were detected in finished water for paired samples, and typically 

at similar low-level concentrations (from August 2004 to January 2005). Some compounds detected in source water were removed or 

transformed during treatment and, therefore, were not detected in finished water (data points on horizontal x-axis). Other compounds 

were detected only in finished water (data points on vertical y-axis). Compounds not identified on the plot include 1,2,4-trimethylbenzene, 

methylene chloride, ethylbenzene, m- and p-xylene, styrene, bisphenol A, and d-limonene. Laboratory Reporting Levels range from 0.02 to 

2.0 micrograms per liter. (Note: The occurrence of disinfection by-products is not shown in this figure due to high concentration values.)

Table 2. Seven compounds that were detected in source and (or) finished water had concentrations 

greater than 0.1 microgram per liter, near Reno, Nevada, 2002–05. None of these concentrations 

exceeded a human-health benchmark; however, benchmarks are available only for five of the seven 

compounds included in this table. 

[Percent occurrence: Estimated concentrations are used for compounds that have reporting level greater than 

Maximum Contaminant Level (MCL) of 0.1 μg/L. Reporting level: Value shown is higher value of either source or 

finished water. MCL or HBSL: MCL values in bold. Abbreviations: μg/L, microgram per liter; E, estimated; HBSL, 

Health-Based Screening Level; THM, trihalomethane; ND, not detected; >, greater than; –, no data]

Name of compound

Number of 

samples analyzed

Percent occurrence 

>0.1 μg/L Reporting 

level

(μg/L)

MCL or 

HBSL

(μg/L)

Maximum concentration 

(μg/L)

Source 

water

Finished 

water

Source 

water

Finished 

water

Source 

water

Finished 

water

Gasoline hydrocarbons and oxygenates

Toluene 25 8 0 75 0.05 1,000 ND 0.180

Disinfection by-products

Chloroform 25 8 0 100 0.024 80 total 

THMs1

ND 16.35

Bromodichloromethane 25 8 0 100 0.048 ND 4.98

Dibromochloromethane 25 8 0 100 0.18 ND 0.975

Manufacturing additives

Bisphenol A 24 8 4 0 1 400 E0.120 ND

Plant- or animal-derived biochemicals

Cholesterol 24 8 4 0 2 – E0.520 ND

3-beta-Coprostanol 24 8 4 0 2 – E0.250 ND

1

MCL of 80 μg/L is for total THMs, including chloroform, bromoform, bromodichloromethane, 

and dibromochloromethane.

}
Human-Health Benchmarks Used in This Assessment 

A screening-level assessment of the potential significance of 

detected compounds to human health was based on a comparison 

of measured concentrations to available human-health benchmarks. 

Specifically, concentrations of regulated compounds were 

compared to USEPA Maximum Contaminant Levels (MCLs), and 

concentrations of unregulated compounds that have USEPA published 

toxicity information were compared to USGS Health-Based Screening 

Levels (HBSLs). The HBSLs were developed in collaboration with 

USEPA, New Jersey Department of Environmental Protection, and 

Oregon Health and Science University (Toccalino and others, 2007). 

About one-half of the detected compounds do not have human-health 

benchmarks or adequate toxicity information for evaluating results 

in a human-health context. Human-health benchmarks are developed 

for individual compounds and not mixtures. The screening-level 

assessment provides an initial perspective on the potential importance 

of “man-made” organic compounds in source water; it is not a 

substitute for a comprehensive risk assessment, which includes many 

more factors, such as additional avenues of exposure. 

was observed at the water intake to the Chalk Bluff Treatment Plant 

at the time of collection of two paired samples with detected gasoline 

hydrocarbons. Seven of the eight gasoline hydrocarbons detected in 

the source water also were detected in the finished water for those two 

samples. A generator used with equipment to bubble air into the stream 

water to prevent ice buildup at the intake gates may have been a source 

of the gasoline hydrocarbons. In a separate paired sample (November 

2004), the petroleum hydrocarbon styrene was detected in source 

and finished waters. One of the most commonly detected compounds 

associated with gasoline is the oxygenate additive methyl tert-butyl 

ether (MTBE) (Kingsbury and others, 2008). Despite the detections of 

eight gasoline hydrocarbons in source and finished waters, no MTBE 

was detected in samples collected for this study. The presence of 

BTEX and other gasoline-related volatile organic compounds (VOCs) 

along with the absence of MTBE in source waters has been observed 

throughout the United States (Grady, 2002). Additionally, MTBE is 

banned in the Lake Tahoe basin so the absence of MTBE in samples 

from the study area is not unexpected.

Six personal care and domestic use products were detected in 

source water samples. Three of these six compounds also were detected 

in finished water samples (table 1). Personal care and domestic use 

products are compounds that are present in commercial products 

sold for personal or residential use (Carter and others, 2007). These 

compounds generally are associated with wastewater discharge (Kolpin 

and others, 2002). However, people swim and raft in Lake Tahoe, the 

reservoirs, and the Truckee River, so this also could be a source. Most 

detections of these compounds were in the autumn and winter, so a 

recreational source is a less likely source of these compounds than 

wastewater discharge.

Potential Effects on Human Health

Concentrations in source- and finished-water generally were less 

than 0.1 μg/L and always less than human-health benchmarks, which 

are available for about one-half of the compounds. On the basis of 

this screening-level assessment, adverse effects to human health are 

expected to be negligible (subject to limitations of available humanhealth benchmarks, see inset “Human-Health Benchmarks Used in 

This Assessment”). 

Although the type of conventional water treatment used by this 

community water system (which is typical of many systems across 

the Nation) is not specifically designed to remove most organic 

compounds, concentrations generally were less than 0.1 μg/L. For 

perspective, reporting limits for public drinking water commonly are 

set through Federal regulations at 0.5 μg/L, and water utilities generally 

are not required to measure below this limit.

Concentrations of seven compounds that were detected in 

source and (or) finished water were greater than or equal to 0.1 μg/L

(table 2). Compounds with concentrations greater than 0.1 μg/L, such 

as toluene, were frequently detected because their physical properties 

allow them to persist in the environment (Zogorski and others, 2006). 

The three disinfection by-product compounds in the finished water 

with concentrations greater than 0.1 μg/L are expected because of 

disinfection with chlorine and chloramine at the water treatment plant 

(Krasner and others, 2006).

Sample concentrations did not exceed drinking-water standards 

for USEPA Maximum Contaminant Levels (MCLs) for regulated 

compounds (table 2) in this study. Concentrations also were less 

than USGS Health-Based Screening Levels (HBSLs) established 

for selected unregulated compounds (see inset “Human-Health 

Benchmarks Used in This Assessment”). 

The USGS screening-level assessment also identified compounds 

at concentrations less than, but within a factor of 10, of humanhealth benchmarks. Only three regulated compounds were detected 

at concentrations less than, but within a factor of 10, of the USEPA 

MCL. These compounds include the disinfection by-products 

(trihalomethanes—chloroform, bromodichloromethane, and 

dibromochloromethane) and the combined concentration of all three 

compounds (total THMs) is within a factor of 10 (table 2). 

An important consideration in assessing potential effects for 

human health is the common occurrence of mixtures of organic 

compounds in source- and finished-water samples. For example, 

nine compounds were detected in paired source and finished water 

samples from the Truckee River. This is comparable to findings from 

eight additional community water systems sampled by the USGS 

(Kingsbury and others, 2008). The potential human-health effects of 

mixtures of co-occurring organic compounds are largely unknown and 

have not been extensively studied. The effect of one compound on 

another’s toxicity may be additive, antagonistic, or synergistic. With a 

few exceptions for pesticides with common modes of action, humanhealth benchmarks generally are not available for specific mixtures. 

Continued research is needed because MCLs and other human-health 

benchmarks generally are based on toxicity data for individual 

compounds, and the effects of specific mixtures of compounds at low 

levels are not well understood (Carpenter and others, 2002; Kingsbury 

and others, 2008).

Truckee River Findings in a National Context and 

Possible Implications

Overall, the compounds detected most commonly in water from 

the Truckee River (tables 1 and 2) are among those most commonly 

detected in ambient stream water and groundwater across the Nation 

(Gilliom and others, 2006; Zogorski and others, 2006). The occurrence 

and concentrations of compounds in source- and finished-water 

samples from the Truckee River also were similar to those detected 

at other community water systems sampled as part of an ongoing 

national NAWQA investigation of rivers (Kingsbury and others, 

2008). However, fewer compounds were detected in the Truckee River 

samples than for most other NAWQA investigations. Additionally, 

findings in a national context are considered preliminary because 

some compounds included in this study only recently have been 

monitored systematically in source and finished waters, including, for 

example, plant- or animal-derived biochemicals (such as cholesterol 

and 3-beta-coprostanol) and those used for personal care, such as 

hexahydrohexamethylcyclopentabenzopyran (HHCB). Continued 

research is needed to better understand sources, transport mechanisms, 

trends, fate in the environment, and possible linkages of these 

compounds to human health.
Source Water-Quality Assessments by the NAWQA 

Program Conducted Across the Nation 

Beginning in 2002, the USGS NAWQA Program initiated 

“Source Water-Quality Assessments” (SWQAs) at selected community 

water systems across the United States (Delzer and Hamilton,2007). The 

long-term goal is to complete as many as 30 SWQAs at systems that 

withdraw water from streams by 2012 using standard protocols and 

nationally consistent methods (U.S. Geological Survey, 1997–2006). 

This fact sheet highlights findings from the Truckee River study, 

which is one of the first nine community water systems sampled. The 

fact sheet serves as a companion product to a USGS Data Series Report 

and a Scientific Investigations Report that present findings for the nine 

systems across the United States (Carter and others, 2007; Kingsbury 

and others, 2008). http://water.usgs.gov/nawqa/swqa

Kingsbury, J.A., Delzer, G.C., and Hopple, J.A., 2008, Anthropogenic 

organic compounds in source water of nine community water 

systems that withdraw from streams, 2002–05: U.S. Geological 

Survey Scientific Investigations Report 2008-5208, 68 p., available 

at http://pubs.er.usgs.gov/usgspubs/sir/sir20085208.

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

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

hormones, and other organic wastewater contaminants in U.S. 

streams, 1999–2000—A national reconnaissance: Environmental 

Science and Technology, v. 36, no. 6, p. 1,202-1,211.

Krasner, S.W., Weinberg, H.S., Richardson, S.D., Pastor, S.J., Chinn, 

R., Sclimenti, M.J., Onstad, G.D., and Thurston, A.D., Jr., 2006, 

Occurrence of a new generation of disinfection byproducts: 

Environmental Science & Technology, v. 40, no. 23, p. 7175-7185.

Toccalino, P.L., Norman, J.E., Booth, N.L., and Zogorski, J.S., 2007, 

Health-Based Screening Levels—A tool for evaluating what waterquality data may mean to human health: U.S. Geological Survey, 

National Water-Quality Assessment Program, accessed June 5, 2008, 

at http://water.usgs.gov/nawqa/HBSL/. 

U.S. Department of Agriculture, 2008, Agricultural Research Service 

(ARS), Pesticide properties database, accessed March 6, 2008, at 

http://www.ams.usda.gov/science/pdp/.

U.S. Environmental Protection Agency, 2007a, Setting standards for 

safe drinking water: U.S. Environmental Protection Agency, Office 

of Ground Water and Drinking Water, accessed June 1, 2007, at 

http://www.epa.gov/safewater/standard/setting.html

U.S. Environmental Protection Agency, 2007b, Unregulated 

Contaminant Monitoring Program: U.S. Environmental Protection 

Agency, accessed January 11, 2009, at http://www.epa.gov/

safewater/ucmr/index.html

U.S. Geological Survey, 1997–2006, National field manual for the 

collection of water-quality data: U.S. Geological Survey Techniques 

of Water-Resources Investigations, book 9, chaps. A1–A9, available 

at http://water.usgs.gov/owq/FieldManual/ (chapters were originally 

published during 1997–1999; updates and revisions are ongoing 

and are summarized at http://water.usgs.gov/owq/FieldManual/

mastererrata.html).

Zogorski, J.S., Carter, J.M., Ivahnenko, Tamara, Lapham, W.W., 

Moran, M.J., Rowe, B.L., Squillace, P.J., and Toccalino, P.L., 2006, 

The quality of our Nation’s waters—Volatile organic compounds 

in the Nation’s ground water and drinking-water supply wells: U.S. 

Geological Survey Circular 1292, 101 p., available at http://pubs.

er.usgs.gov/usgspubs/cir/cir1292

By Karen A. Thomas

USGS promotes public access to water-quality information

This fact sheet, additional data and investigations reports, and other 

information are available on the World Wide Web at http://water.usgs.gov/

nawqa/swqa. Included at this Web site are downloadable data on organic

compound occurrence, information on sampling designs and methodology, 

background on data analyses, and frequently asked questions.

Contacts for additional information 

For more information concerning the research in this report, contact the 

Director, Nevada Water Science Center 

U.S. Geological Survey 2730 N. Deer Run Road 

Carson City, Nevada 89701 

http://nevada.usgs.gov/water/

Publishing support provided by the U.S. Geological Survey 

Publishing Network, Tacoma Publishing Service Center

USGS will continue to collaborate with, and complement the 

work of other Federal, State, and local organizations, and to continue 

to communicate findings, possible implications, and future needs, 

including, for example: 

• Increased emphasis on watershed management and source-water 

protection strategies to help minimize the sources and transport of 

compounds to source water and ultimately to finished water.

• Continued research will enhance information about toxicity in 

commonly occurring unregulated compounds and mixtures that are 

detected in source and finished water.

• Current and future monitoring and assessment of compounds not 

typically monitored in source water, but commonly present in 

finished water, which may identify or lead to the development of 

treatment technologies for their removal. 

References Cited

Bevans, H.E., Lico, M.S., and Lawrence, S.J., 1998, Water quality in 

the Las Vegas Valley area and the Carson and Truckee River basins, 

Nevada and California, 1992–96: U.S. Geological Survey Circular 

1170, 47 p., available at http://pubs.usgs.gov/circ/circ1170 

Carpenter, D.O., Arcaro, K., and Spink, D.C., 2002, Understanding the 

human health effects of chemical mixtures: Environmental Health 

Perspectives, v. 110, p. 25-42.

Carter, J.M., Delzer, G.C., Kingsbury, J.A., and Hopple, J.A., 2007, 

Concentration data for anthropogenic organic compounds in ground 

water, surface water, and finished water of selected community 

water systems in the United States, 2002–05: U.S. Geological 

Survey Data Series 268, 30 p., available at http://pubs.usgs.gov/

ds/2007/268

Delzer, G.C., and Hamilton, P.A., 2007, National Water-Quality 

Assessment Program—Source Water-Quality Assessments: U.S. 

Geological Survey Fact Sheet 2007–3069, 2 p., available at http://

pubs.er.usgs.gov/usgspubs/fs/fs20073069 

Gilliom, R.J., Barbash, J.E., Crawford, C.G., Hamilton, P.A., Martin, 

J.D., Nakagaki, Naomi, Nowell, L.H., Scott, J.C., Stackelberg, P.E., 

Thelin, G.P., and Wolock, D.M., 2006, The quality of our Nation’s 

waters—Pesticides in the Nation’s streams and ground water, 

1992–2001: U.S. Geological Survey Circular 1291, 172 p., available 

at http://pubs.er.usgs.gov/usgspubs/cir/cir1291

Grady, S.J., 2002, National survey of Methyl tert-Butyl Ether and other 

volatile organic compounds in drinking-water sources—Results 

of the random survey: U.S. Geological Survey Water-Resources 

Investigations Report 02-4079, 85 p., available at http://sd.water.

usgs.gov/nawqa/pubs/wrir/wrir02_4079.html