Prepared in cooperation with the Columbia River Inter-Tribal Fish Commission

and the Lower Columbia Estuary Partnership

Reconnaissance of Contaminants in Selected WastewaterTreatment-Plant Effluent and Stormwater Runoff Entering the 

Columbia River, Columbia River Basin, Washington and Oregon, 

2008–10

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Report 2012–5068
Cover:

Top: 

Near the confluence with the Willamette River, looking upstream on the Columbia River towards Mount Hood, Oregon, October 2008.

Bottom left: 

Under the Marquam Bridge, stormwater pipe draining to the Willamette River, downtown Portland, Oregon, April 2009.

Bottom center:

Warning sign at boat ramp in Cathedral Park on the Willamette River, Portland, Oregon, May 2008.

Bottom right:

Clarifier at Wenatchee Wastewater-Treatment Plant, Washington, December 2009.

(All photographs taken by Jennifer Morace, U.S. Geological Survey.)
Reconnaissance of Contaminants in 

Selected Wastewater-Treatment-Plant 

Effluent and Stormwater Runoff Entering the 

Columbia River, Columbia River Basin, 

Washington and Oregon, 2008–10

By Jennifer L. Morace

Prepared in cooperation with the Columbia River Inter-Tribal Fish Commission

and the Lower Columbia Estuary Partnership

Scientific Investigations Report 2012–5068

U.S. Department of the Interior

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

KEN SALAZAR, Secretary

U.S. Geological Survey

Marcia K. McNutt, Director

U.S. Geological Survey, Reston, Virginia: 2012

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U.S. Government.

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

reproduce any copyrighted materials contained within this report.

Suggested citation:

Morace, J.L., 2012, Reconnaissance of contaminants in selected wastewater-treatment-plant effluent and stormwater 

runoff entering the Columbia River, Columbia River Basin, Washington and Oregon, 2008–10: U.S. Geological Survey 

Scientific Investigations Report 2012–5068, 68 p. 
iii

Contents

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

Introduction.....................................................................................................................................................1

Purpose and Scope .............................................................................................................................2

Sampling Design and Methods ...................................................................................................................3

Sampling Sites.......................................................................................................................................3

Sampling and Analytical Methods ....................................................................................................7

Analytical Methods for Wastewater-Treatment-Plant-Effluent Samples ..........................9

Analytical Methods for Stormwater-Runoff Samples..........................................................10

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

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

Results of Quality-Control Data ...............................................................................................14

Compound Classes ......................................................................................................................................16

Anthropogenic Organic Compounds ...............................................................................................16

Pharmaceuticals.................................................................................................................................16

Halogenated Compounds ..................................................................................................................16

Currently Used Pesticides.................................................................................................................17

Polycyclic Aromatic Hydrocarbons.................................................................................................17

Trace Elements and Mercury............................................................................................................17

Contaminant Concentrations in Wastewater-Treatment-Plant Effluent.............................................18

Anthropogenic Organic Compounds ...............................................................................................18

Pharmaceuticals.................................................................................................................................21

Estrogenicity........................................................................................................................................22

Halogenated Compounds ..................................................................................................................24

Currently Used Pesticides.................................................................................................................24

Mercury................................................................................................................................................24

Synopsis ...............................................................................................................................................24

Contaminant Concentrations in Stormwater Runoff .............................................................................29

Halogenated Compounds ..................................................................................................................29

Currently Used Pesticides.................................................................................................................32

Polycyclic Aromatic Hydrocarbons.................................................................................................35

Trace Elements and Mercury............................................................................................................35

Oil and Grease.....................................................................................................................................40

Synopsis ...............................................................................................................................................40

Implications for Columbia River Basin .....................................................................................................42

Four Case Studies...............................................................................................................................42

Loadings to the River.................................................................................................................43

Comparison to SB 737 Plan Initiation Levels..................................................................................43

Future Directions..........................................................................................................................................47

Sampling Design .................................................................................................................................47

Information Gaps.................................................................................................................................48

Summary and Conclusions.........................................................................................................................48

Acknowledgments.......................................................................................................................................50

References Cited..........................................................................................................................................50

Appendix A. Methods, Reporting Limits, and Analyte Information..................................................57
iv

Figures

Figure 1. Map showing cities where samples were collected from wastewatertreatment plants and stormwater runoff in the Columbia River Basin, 

Washington and Oregon, 2008–10 ......................................................... 4

Figure 2. Map showing selected stormwater-runoff sampling locations in the Portland,

Oregon, and Vancouver, Washington, area, Columbia River Basin, 2009–10......... 6

Figure 3. Graph showing percentage of compounds detected in wastewater-treatmentplant effluent, Columbia River Basin, Washington and Oregon, 2008–09 ............ 27

Figure 4. Graph showing ratio of filtered to unfiltered concentrations of trace elements

measured in stormwater runoff, Columbia River Basin, Washington and Oregon,

2009–10 ....................................................................................... 38

Figure 5. Graph showing percentage of compounds detected in stormwater runoff,

Columbia River Basin, Washington and Oregon, 2009–10 .............................. 40

Figure 6. Graph showing concentrations of diphenhydramine, trimethoprim, galaxolide,

and nonylphenol compounds in wastewater-treatment-plant-effluent samples,

Columbia River Basin, Oregon, 2008–09................................................... 42

Tables

Table 1. Precipitation, population, age, and income information for cities where samples

were collected, Columbia River Basin, Washington and Oregon ..................... 3

Table 2. Descriptions of wastewater-treatment plants where samples were collected,

Columbia River Basin, Washington and Oregon, 2008–09 .............................. 5

Table 3. Stormwater-runoff sampling locations in the Columbia River Basin, Washington

and Oregon, 2009–10 ........................................................................ 5

Table 4. Summary of sampling activities, Columbia River Basin, Washington and Oregon,

2008–10 ....................................................................................... 8

Table 5. Summary of quality-control (QC) analyses performed for this study, Columbia

River Basin, Washington and Oregon, 2008–10 .......................................... 11

Table 6. Summary of surrogate recoveries, Columbia River Basin, Washington and

Oregon, 2008–10 ........................................................................... 12

Table 7. Summary of detections in blank samples, Columbia River Basin, Washington 

and Oregon, 2008–10 ........................................................................ 14

Table 8. Summary of relative percent differences for replicate samples, Columbia

River Basin, Washington and Oregon, 2008–10 .......................................... 15

Table 9. Anthropogenic organic compounds detected in unfiltered wastewatertreatment-plant effluent, Columbia River Basin, Washington and

Oregon, 2008–09 ........................................................................... 19

Table 10. Pharmaceuticals detected in filtered wastewater-treatment-plant effluent,

Columbia River Basin, Washington and Oregon, 2008–09 .............................. 21

Table 11. Estrogenicity in wastewater-treatment-plant effluent samples, instantaneous

loadings, and calculated concentrations in the Columbia River, Columbia River

Basin, Washington and Oregon, December 2008 ....................................... 22
v

Tables—Continued

Table 12. Physical properties and suspended-sediment results for wastewatertreatment-plant effluent, Columbia River Basin, Washington and

Oregon, 2008–09 ........................................................................... 23

Table 13. Halogenated compounds detected in solids filtered from

wastewater-treatment-plant effluent, Columbia River Basin, Washington 

and Oregon, 2008–09 ........................................................................ 25

Table 14. Currently used pesticides and degradates detected in filtered

wastewater-treatment-plant effluent, Columbia River Basin, Washington 

and Oregon, December 2009 ............................................................... 26

Table 15. Mercury species in unfiltered wastewater-treatment-plant effluent and

stormwater runoff, Columbia River Basin, Washington and Oregon, 2009–10 ...... 27

Table 16. Percentage of compounds detected in each wastewater-treatment plant

sampled, Columbia River Basin, Washington and Oregon, 2008–09 .................. 28

Table 17. Halogenated compounds detected in solids filtered from stormwater runoff,

Columbia River Basin, Washington and Oregon, 2009–10 .............................. 30

Table 18. Physical properties and suspended-sediment results for stormwater runoff,

Columbia River Basin, Washington and Oregon, 2009–10 .............................. 32

Table 19. Currently used pesticides and degradates detected in filtered stormwater 

runoff, Columbia River Basin, Washington and Oregon, 2009–10 ..................... 33

Table 20. Concentrations exceeding freshwater-quality criteria for pesticides and

polychlorinated biphenyls (PCBs) in stormwater runoff from the Willamette2 

site, Columbia River Basin, Washington and Oregon, December 2009 and 

May 2010 .................................................................................... 34

Table 21. Polycyclic aromatic hydrocarbons (PAHs) detected in unfiltered stormwater

runoff, Columbia River Basin, Washington and Oregon, 2009–10 ..................... 36

Table 22. Trace elements detected in stormwater runoff, Columbia River Basin,

Washington and Oregon, 2009–10 ......................................................... 37

Table 23. Concentrations exceeding freshwater-quality criteria for trace elements in

stormwater runoff, Columbia River Basin, Washington and Oregon, 2009–10 ...... 39

Table 24. Oil and grease detected in stormwater runoff, Columbia River Basin, 

Washington and Oregon, 2009–10 ......................................................... 40

Table 25. Instantaneous loadings and calculated concentrations for diphenhydramine,

trimethoprim, galaxolide, and nonylphenol compounds in the Columbia River,

Columbia River Basin, Washington and Oregon, 2008–09 .............................. 44

Table 26. Oregon Senate Bill 737 priority persistent pollutants not detected in

wastewater-treatment-plant (WWTP) effluent, Columbia River Basin, 

Washington and Oregon, 2008–09 ......................................................... 45

Table 27. Oregon Senate Bill 737 priority persistent pollutants detected in

wastewater-treatment-plant (WWTP) effluent, Columbia River Basin, 

Washington and Oregon, 2008–09 ......................................................... 46
vi

Conversion Factors, Datums, and Abbreviations and 

Acronyms

Conversion Factors

Inch/Pound to SI

Multiply By To obtain

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

square mile (mi2) 2.590 square kilometer (km2)

cubic foot per second (ft3/s) 0.02832 cubic meter per second (m3/s)

million gallons per day (Mgal/d) 1.547 cubic meter per second (m3/s)

SI to Inch/Pound

Multiply By To obtain

gram per day (g/d) 0.03527 ounce, avoirdupois (oz)

liter (L) 0.2642 gallon (gal)

liter per day (L/d) 0.2642 gallon per day (gal/d)

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

°F=(1.8×°C)+32.

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

micrograms per liter (μg/L), or nanograms per liter (ng/L).

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

25 °C).

CAS Registry Numbers® is a Registered Trademark of the American Chemical Society. CAS 

recommends the verification of the CASRNs through CAS Client ServicesSM.

Datums

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

(NAVD 88).

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

Abbreviations and Acronyms

7Q10 the lowest streamflow for seven consecutive days that occurs on average once every 10 years

AOC anthropogenic organic compounds

CAS Chemical Abstracts Service

CERC Columbia Environmental Research Center

CSO Combined sewer overflow

E estimated

EEQ estradiol equivalent factor

EPA U.S. Environmental Protection Agency

GC/MS gas chromatography/mass spectrometry

MDL Method detection limit

NPDES National Pollutant Discharge Elimination System

NWQL National Water-Quality Laboratory

ODEQ Oregon Department of Environmental Quality

PAH Polycyclic aromatic hydrocarbons

PBDE Polybrominated diphenyl ethers

PCB Polychlorinated biphenyls

PIL plan initiation level (SB 737)

QC quality control

RL Reporting limit

RPD relative percent difference

SB Senate Bill

USGS U.S. Geological Survey

WWTP Wastewater-treatment plant

YES Yeast estrogen screen

Conversion Factors, Datums, and Abbreviations and 

Acronyms—Continued
viii

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Reconnaissance of Contaminants in Selected 

Wastewater-Treatment-Plant Effluent and Stormwater 

Runoff Entering the Columbia River, Columbia River Basin, 

Washington and Oregon, 2008–10

By Jennifer L. Morace

Abstract

Toxic contamination is a significant concern in the 

Columbia River Basin in Washington and Oregon. To help 

water managers and policy makers in decision making about 

future sampling efforts and toxic-reduction activities, a 

reconnaissance was done to assess contaminant concentrations 

directly contributed to the Columbia River through 

wastewater-treatment-plant (WWTP) effluent and stormwater 

runoff from adjacent urban environments and to evaluate 

instantaneous loadings to the Columbia River Basin from 

these inputs.

Nine cities were selected in Oregon and Washington to 

provide diversity in physical setting, climate characteristics, 

and population density—Wenatchee, Richland, Umatilla, The 

Dalles, Hood River, Portland, Vancouver, St. Helens, and 

Longview. Samples were collected from a WWTP in each 

city and analyzed for anthropogenic organic compounds, 

pharmaceuticals, polychlorinated biphenyls (PCBs), 

polybrominated diphenyl ether (PBDEs [brominated flameretardants]), organochlorine or legacy compounds, currently 

used pesticides, mercury, and estrogenicity. Of the 210 

compounds analyzed in the WWTP-effluent samples, 112 

(53 percent) were detected, and the detection rate for most 

compound classes was greater than 80 percent. Despite the 

differences in location, population, treatment type, and plant 

size, detection frequencies were similar for many of the 

compounds detected among the WWTPs. By contrast, the 

occurrence of polycyclic aromatic hydrocarbons (PAHs) was 

sporadic, and PCBs were detected at only three WWTPs. 

The stormwater-runoff samples were analyzed for a 

slightly different set of contaminants, with the focus on those 

expected to be related to road and land runoff—PCBs, PBDEs, 

organochlorine compounds, PAHs, currently used pesticides, 

trace elements, mercury, and oil and grease. A complex 

mixture of compounds was detected in stormwater runoff, 

with detections of 114 (58 percent) of the 195 compounds 

analyzed. The detection patterns and concentrations measured 

in the stormwater-runoff samples, however, were more 

heterogeneous than in the WWTP-effluent samples. This 

reflects differences in various factors, including suspendedsediment concentrations and known contamination sources 

present in some watersheds. Trace elements and PAHs, which 

are related to automobiles and impervious surfaces, were the 

most widespread compound classes detected in stormwater 

runoff, a typical finding in stormwater runoff in urban areas. 

With a better understanding of the presence of these 

contaminants in the environment, future work can focus 

on developing research to characterize the effects of these 

contaminants on aquatic life and prioritize toxic-reduction 

efforts for the Columbia River Basin.

Introduction

The Columbia River drains 259,000 square miles of the 

Pacific Northwest, and flows more than 1,200 miles from its 

headwaters in the Canadian Rockies of British Columbia. 

The river drains areas in Montana, Idaho, Washington, 

Oregon, and Wyoming, before flowing along the border of 

Washington and Oregon to its mouth at the Pacific Ocean. 

The rivers and streams of the Columbia River Basin carry 

the fourth largest volume of runoff in North America. The 

approximately 8 million people who live in the basin depend 

on its resources for their health and livelihood (Independent 

Scientific Advisory Board, 2007; U.S. Environmental 

Protection Agency, 2009a). Similarly, hundreds of fish 

and wildlife species, including 12 stocks of threatened and 

endangered salmonid species, rely on the ecosystem for their 

food sources, security, and habitat. Therefore, the Columbia 

River Basin is of environmental and cultural significance for 

all its inhabitants. 

With growing scientific concern about the health of 

the ecosystem, efforts have been increased to make the 

public aware of the presence of toxic contaminants in the 

environment and the unknowns with regard to the potential 
2 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

adverse effects of these contaminants on the 

inhabitants of the ecosystem. Contaminants are 

chemicals introduced to the environment in amounts 

that can be harmful to fish, wildlife, or people. 

Many of these contaminants enter the environment 

through the production, use, and disposal of 

numerous chemicals that offer improvements in 

industry, agriculture, medical treatment, and common 

household conveniences. 

Several studies have been completed throughout 

the Columbia River Basin in the past 10–20 years in 

an effort to characterize contaminant concentrations 

in water, sediment, and fish. In 2005, the U.S. 

Environmental Protection Agency (EPA) joined other 

Federal, State, Tribal, local, and nongovernmental 

organizations in forming the Columbia River Toxics 

Reduction Working Group in an effort to coordinate 

this work and share information. The goal of the 

group is to reduce toxics in the basin and prevent 

further contamination. In 2009, EPA produced the 

State of the River Report for Toxics to document the 

current knowledge in the basin with regard to certain 

classes of compounds, and to open communication 

for developing future solutions for addressing toxics 

reduction (U.S. Environmental Protection Agency, 

2009a).

Through this process, the working group 

acknowledged that an adequate understanding 

of sources of these contaminants must precede 

development of efficient and effective toxic-reduction 

efforts. In a national survey of 139 streams in 1999–

2000, organic wastewater contaminants were detected 

in 80 percent of the streams surveyed (Kolpin and 

others, 2002). Of the 95 contaminants analyzed, fecal 

steroids, insect repellants, caffeine, antimicrobial 

disinfectants, fire retardants, and nonionic detergent 

metabolites were commonly detected classes. In 

2004–05, some of these same pharmaceuticals, 

antibiotics, and anthropogenic organic compounds 

(AOCs) were analyzed in samples collected from 

the main stem Columbia River near Portland 

and Longview (Lower Columbia River Estuary 

Partnership, 2007). Less than 20 contaminants 

were detected in these filtered-water samples at 

concentrations less than 1 microgram per liter (μg/L, 

parts-per-billion) range (Morace, 2006). This would 

suggest that the large volume of water flowing in the 

Columbia River dilutes the concentrations of these 

manmade contaminants. In contrast, when Nilsen 

and others (2007) analyzed surficial bed sediments 

in the lower Columbia River main stem and several 

tributaries, 49 different AOCs were detected, 

supporting the need to analyze multiple media when 

assessing contaminant issues. Nilsen and others 

(2007) detected endocrine-disrupting compounds 

(contaminants that block or mimic hormones in the 

body and cause harm to fish and wildlife) at 22 of 23 sites sampled, 

with concentrations in the parts-per-billion range. The studies hint at 

the presence of these contaminants in the environment, but the extent of 

their presence throughout the basin is poorly understood. 

Recent research has raised questions about potential effects on 

fish, shellfish, wildlife, and human health from even trace exposure to 

these contaminants, including chronic effects (Kidd and others, 2007; 

Ings and others, 2011), reproductive disruption (Vajda and others, 2008; 

Colman and others, 2009; Jenkins and others, 2009), and physiological 

changes (Hoy and others, 2011). Little is known, however, about the 

extent of the environmental occurrence, transport, and ultimate fate of 

these contaminants in the Columbia River ecosystem. To efficiently and 

effectively reduce loadings of these compounds to the river, sources 

and pathways of contaminants need to be identified. Numerous studies 

have shown that WWTP effluent and stormwater runoff contribute 

contaminants to their receiving waters (Boyd and others, 2004; Kolpin 

and others, 2004; Glassmeyer and others, 2005; Phillips and Chalmers, 

2009). These two pathways act as integrators of human activities and 

offer an area where changes could be made to lessen their effects on the 

environment. This study focused on WWTP effluent and stormwater 

runoff to characterize how potential contaminants could be contributed 

through these pathways. A better understanding of the way contaminants 

enter the Columbia River Basin may help water managers reduce of the 

occurrence of contaminants in the basin.

Purpose and Scope 

This report presents the results of a study to (1) assess 

contaminant concentrations directly contributed to the Columbia River 

through WWTP effluent and stormwater runoff from adjacent urban 

environments, (2) evaluate instantaneous loadings to the Columbia 

River Basin from inputs of this type, and (3) provide information to 

water managers and policy makers to help with decision making about 

Interstate Highway 5 (I-5) bridge on the Columbia River from Hayden Island, Portland, 

Oregon, October 2009.
Sampling Design and Methods 3

future sampling efforts and reduction activities. The data from 

this study provide an initial assessment of a broad array of 

contaminants that to date have little information available on 

different sources in the Columbia River Basin. These data will 

be a useful first step to (1) identify the contaminants of highest 

interest, (2) indicate the most important sources of these 

contaminants, and (3) prioritize contaminant-reduction efforts.

This investigation resulted from a scientific and financial 

partnership between the USGS, Columbia River Inter-Tribal 

Fish Commission, Lower Columbia Estuary Partnership, 

Columbia Riverkeeper, and Northwest Environmental Defense 

Center, all agencies involved in the Columbia River Toxics 

Reduction Working Group.

Sampling Design and Methods

Sampling Sites

This study was designed to characterize WWTP effluent 

and stormwater runoff directly entering the Columbia River. 

These pathways were examined separately, however, by 

focusing specifically on what contaminants were of interest 

for each pathway. This study was not designed as a paired 

study to compare the differences in these pathways, but rather 

to characterize what could be contributed by each. Because 

this was a reconnaissance study, the cities where samples 

were collected were selected throughout the basin to provide 

Table 1. Precipitation, population, age, and income information for cities where samples were collected, Columbia River Basin, 

Washington and Oregon.

[Data from U.S. Census Bureau (2010). Symbols: <, less than; >, greater than]

City State County

Average

annual

precipitation 

(inches)

Population

Population

density 

(people per 

square mile)

Population age 

distribution

(percent)

Median

age

(years)

Median

annual 

household 

income

(U.S. dollars)

Average 

household

size

(persons) <18 

years

18–65 

years

>65 

years

Wenatchee Washington Chelan 9 31,925 4,110 25 61 14 36.4 $42,600 2.55

Richland Washington Benton 7 48,058 1,350 25 62 13 38.4 $62,200 2.53

Umatilla Oregon Umatilla 8 6,906 1,560 23 73 4 31.5 $46,800 3.08

The Dalles Oregon Wasco 14 13,620 2,150 25 57 18 39.3 $44,100 2.40

Hood River Oregon Hood River 32 7,167 2,810 28 58 14 34.9 $47,200 2.43

Portland Oregon Multnomah 37 583,776 4,380 20 70 10 35.5 $48,100 2.27

Vancouver Washington Clark 42 161,791 3,480 24 64 12 35.6 $48,000 2.46

St. Helens Oregon Columbia 46 12,883 2,840 28 64 8 33.3 $53,500 2.74

Longview Washington Cowlitz 48 36,648 2,530 24 60 16 39.1 $39,000 2.32

a range in sampling location, population characteristics, and 

climate setting—in downstream order along the Columbia 

River, they include Wenatchee, Richland, Umatilla, The 

Dalles, Hood River, Portland, Vancouver, St. Helens, and 

Longview (fig. 1, table 1). 

In each city, one sample was collected from the WWTP 

effluent just prior to where it enters the river (table 2). 

These one-time samples represented a variety of treatment 

techniques varying by the size of the treatment plant and 

the type of disinfection used. This study was not designed 

to evaluate these treatment techniques or differentiate the 

associated concentrations, but rather to collect preliminary 

data. A stormwater-runoff sample also was collected directly 

from a pipe in each city just prior to where the runoff enters 

the receiving waters, except for in Umatilla, Oregon, where 

the stormwater flowed into a percolation field (table 3). 

In the Portland/Vancouver area (fig. 2), extra samples were 

collected—two locations in Vancouver, Washington, and two 

locations in Portland, Oregon, where stormwater enters the 

Columbia River. Rather than draining directly to the Columbia 

River, much of the stormwater from the eastern Portland 

area is delivered to the Columbia Slough (fig. 2) which flows 

through Portland and enters the Willamette River just before 

it converges with the Columbia River. Much of the remaining 

stormwater from the western and southern areas of Portland 

flows through pipes into the Willamette River. For this 

study, stormwater runoff from four pipes discharging to the 

Willamette River also was sampled. 
4 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

tac11-0618_fig01

YAKIMA

KING

OKANOGAN

CANADA

GRANT

LEWIS

CHELAN

UMATILLA

FERRY

WASCO

ADAMS

KITTITAS

LINCOLN

SKAGIT

PIERCE

WHATCOM

MORROW

BENTON

KLICKITAT

UNION

DOUGLAS

CLALLAM

SNOHOMISH

STEVENS

SKAMANIA

PACIFIC

GILLIAM

CLACKAMAS

MARION

JEFFERSON

MASON

POLK

COWLITZ

FRANKLIN

GRAYS HARBOR

CLATSOP

TILLAMOOK

LINN

WHEELER

CLARK

WALLA WALLA

YAMHILL

BAKER

KITSAP

ISLAND

THURSTON

COLUMBIA

SHERMAN

SAN JUAN

WASHINGTON

WHITMAN

HOOD

RIVER

MULTNOMAH

WAHKIAKUM

WALLOWA

GARFIELD

Warrendale

Point

Adams

Umatilla

Portland

The Dalles

Hood 

River

St. Helens

Point

Adams

Bonneville Dam

Warrendale

Longview

Richland

Vancouver

Wenatchee

Yakima River

Columbia 

 River

Lewis River

Snake River

Cowlitz River

Entiat River

Klickitat River

Chelan River

Touchet River

Naches River

Tualatin River

Kalama River

White River

Green River

Chehalis River

Cle Elum River

Umatilla River

Wind River

Mad River

Walla 

 Walla 

 River

Grays River

Chiwawa River

Nehalem River

Wilson River

Naselle River

Clatskanie River

Salmon 

 River

Tye River

Teiton

River

Fall River

Youngs River

Little Klickitat River

Black 

River

Rapid River

Waptus

 River

Dog River

Toutle River

Sandy River

 East Fork

Hood River

Nestucca River

Collawash River

Yamhill 

River

Bear River

Cispus River

Clackamas River

Columbia River

Cispus River

SPOKANE

124°W 122°W 120°W 118°W

48°N

46°N

0 25 50 75 100 MILES

0 25 50 75 100 KILOMETERS

Clarke 1866 Albers Projection

Central meridian 121°W 

North American Datum 1983

Tacoma

Seattle

Portland

Spokane

Yakima

Vancouver

Columbia 

River 

Basin

IDAHO

WASHINGTON

OREGON

MONTANA

CANADA

PACIFIC OCEAN

CANADIAN

ROCKIES

BRITISH

COLUMBIA

WYOMING

Figure 1. Cities where samples were collected from wastewater-treatment plants and stormwater runoff in the Columbia River 

Basin, Washington and Oregon, 2008–10.
Sampling Design and Methods 5

Table 2. Descriptions of wastewater-treatment plants where samples were collected, Columbia River Basin, Washington and Oregon, 

2008–09.

[Cities shown in downstream order. Abbreviations: Mgal/d, million gallons per day; 7Q10, the lowest streamflow for 7 consecutive days that occurs on average 

once every 10 years; ft3/s, cubic foot per second; UV, ultraviolet; WWTP, wastewater treatment plant; NA, not available]

City Station name

Point of 

discharge, 

Columbia 

River 

mile

Permit 

design 

flow

(Mgal/d)

Columbia 

River 7Q10 

streamflow

(ft3/s)

Wastewater-treatment 

plant description

Wenatchee City of Wenatchee WWTP effluent at Wenatchee, Wash. 466.6 7.1 51,557 Activated sludge plant, secondary-level 

treatment and UV disinfection.

Richland City of Richland WWTP effluent at Richland, Wash. 337.1 11.4 52,700 Semi-plug flow conventional activated 

sludge, secondary clarification, and 

chlorination.

Umatilla City of Umatilla WWTP effluent at Umatilla, Oreg. 289 0.92 NA Oxidation ditch with UV disinfection.

The Dalles City of The Dalles WWTP effluent at The Dalles, Oreg. 189.5 4.15 80,637 Activated sludge plant with UV 

disinfection.

Hood River City of Hood River WWTP effluent at Hood River, Oreg. 165 2 74,000 Activated sludge plant with UV 

disinfection.

Portland Columbia Blvd WWTP effluent at Hayden Island, Oreg. 105.5 72 79,436 Conventional activated sludge, secondary 

clarification, chlorine disinfection.

Vancouver Vancouver Westside WWTP effluent at Vancouver, Wash. 105 28 79,436 Industrial Pretreatment Lagoon, secondary 

activated sludge, UV disinfection, 

sludge incineration.

St. Helens City of St. Helens WWTP effluent at St. Helens, Oreg. 86.9 45 88,900 Combined municipal and kraft mill 

aerated stabilization basin.

Longview Three Rivers Regional WWTP effluent at Longview, Wash. 67.5 26 97,400 Conventional activated sludge, secondary 

clarification, chlorine disinfection, 

dechlorination. 

Table 3. Stormwater-runoff sampling locations in the Columbia River Basin, Washington and Oregon, 2009–10.

[Outfalls are shown in downstream order]

Short name Outfall station name County Station No. Date Time

Wenatchee Wenatchee stormwater outfall at Chehalis Street near footbridge, Wash. Chelan 472506120180900 12-21-09 1340

Richland Richland stormwater outfall near Columbia Park West, Wash. Benton 461414119125400 05-02-09 1200

Umatilla Umatilla stormwater outfall south end of percolation field, Oreg. Umatilla 455448119205900 10-04-09 0920

The Dalles The Dalles stormwater outfall at Klindt Point, Oreg. Wasco 453750121115300 02-23-09 1210

Hood River Hood River stormwater outfall near Nichols Basin, Oreg. Hood River 454256121304100 02-23-09 1310

Portland1 Stormwater outfall near I-205 bridge at northeast 112th Avenue, Oreg. Multnomah 453424122324400 10-14-09 1100

Vancouver1 Stormwater outfall near southeast corner of Fort Vancouver, Wash. Clark 453705122393300 12-16-09 1340

Vancouver2 Stormwater outfall under I-5 bridge at Vancouver, Wash. Clark 453717122402400 12-16-09 1210

Portland2 Stormwater outfall under I-5 bridge on Hayden Island, Oreg. Multnomah 453651122403900 10-26-09 1210

Willamette1 Stormwater outfall downstream of west end of Marquam Bridge, Oreg. Multnomah 453025122401700 06-04-10 0840

Willamette2–Dec. Stormwater outfall under west end of St. John’s railroad bridge, Oreg. Multnomah 453431122445800 12-15-09 1330

Willamette2–May Stormwater outfall under west end of St. John’s railroad bridge, Oreg. Multnomah 453431122445800 05-26-10 1310

Willamette3 Stormwater outfall downstream of west end of St. John’s railroad bridge, Oreg. Multnomah 453431122445900 12-15-09 1310

Willamette4 Stormwater outfall west end North Ramsey Boulevard, Oreg. Multnomah 453726122471500 05-26-10 1410

St Helens St Helens stormwater outfall at boat launch on River Street, Oreg. Columbia 455203122475600 03-30-10 1310

Longview Longview stormwater ditch at 99 Oregon Way, Wash. Cowlitz 460703122570000 03-30-10 1410
6 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

tac11-0618_fig02

0 4 MILES

0 4 KILOMETERS

2

2

Portland1

Portland2

Willamette1

Willamette4

Willamette3

Willamette2

Vancouver1

Vancouver2

Portland1

Portland2

Willamette1

Willamette4

Willamette3

Willamette2

Vancouver1

Vancouver2

45 ̊35’

45 ̊37’30”

122 ̊50’ 122 ̊45’ 122 ̊40’ 122 ̊35’

45 ̊32’30”

Base from U.S. Geological Survey

1:24,000-scale digital data

EXPLANATION

Willamette1 Stormwater-runoff sampling location

Columbia Slough

Willamette River

Columbia River

Figure 2. Selected stormwater-runoff sampling locations in the Portland, Oregon, and Vancouver, Washington, area, 

Columbia River Basin, 2009–10.

Many cities, and Portland in particular, have older sewer 

systems that mix untreated sewage and stormwater runoff. 

When it rains, these systems are overwhelmed and combined 

sewer overflows (CSOs) carry untreated sewage to the 

receiving waters. During wet weather, Portland’s combined 

sewers overflow into the Willamette River an average of 

100 times per year (Portland Bureau of Environmental 

Services, 2010). Phillips and Chalmers (2009) have shown that 

untreated discharge from CSOs can be an important source 

of contaminants to receiving waters. In an effort to prevent 

these CSOs and improve water quality, the city of Portland has 

constructed several “big pipes”—the Columbia Slough Big 

Pipe (completed in 2000), the West Side Big Pipe (completed 

in 2006), and the East Side Big Pipe (completed in 2011) 

(Portland Bureau of Environmental Services, 2010). These 

large (12- to 22-ft diameter) pipes help store and transport 

the overflow so that it can be treated before it is discharged. 

Combined sewer overflows to the Willamette River will be 

reduced by 94 percent when all east-side CSO construction is 

complete. These Big Pipes influenced the sampling locations 

for this study because they prevent stormwater pipes from 

delivering runoff to locations that previously received the 

runoff. Sites selected on the west side of the Willamette River 

are upstream (Willamette1) and downstream (Willamette2 and 

Willamette3) of the Big Pipe drainage areas (fig. 2). 
Sampling Design and Methods 7

Sampling and Analytical Methods 

To characterize the nature of the water entering 

the Columbia River, each sample was collected in 

the WWTP at a point in the effluent stream past any 

treatment and just before the effluent enters the river. 

This was a dip sample in the effluent stream at most 

WWTPs, but in Longview, St. Helens, and Portland, 

the samples were pumped into the bottles by the 

onsite pumps. One sample was collected at each of 

the nine cities, except at Portland where samples 

were collected three times throughout the day 

(9 a.m., 12 p.m., and 3 p.m.) to examine temporal 

variability (table 4). Therefore, 11 WWTP‐effluent 

samples were collected. 

Similar to the samples collected at WWTPs, the 

stormwater samples were collected from the end of 

the pipe just before it entered the river. One sample 

was collected at each of the nine cities, except in 

Portland and Vancouver, where two locations were 

sampled in each city. An additional four stormwater 

locations were sampled along the Willamette River 

in an effort to better characterize stormwater runoff 

in the Portland area. Thus, a total of 15 locations 

were sampled for stormwater runoff. 

The original project plan did not include 

analysis of currently used pesticides in WWTPeffluent samples. Because pesticides make up 34 

percent of the persistent pollutants list in Oregon 

Senate Bill (SB) 737 (Oregon Department of 

Environmental Quality, 2010a), however, a decision 

was made to revisit each WWTP during December 

2009 to collect samples of effluent for analysis 

of pesticides and mercury. Oregon Department 

of Environmental Quality (ODEQ) was required 

by SB 737 to develop a list of priority persistent 

bioaccumulative toxics (persistent pollutants) 

that have a documented effect on human health, 

wildlife, and aquatic life. The 52 largest municipal 

WWTPs in Oregon analyzed their effluent in July 

and November 2010 for these persistent pollutants, 

and they currently are developing reduction plans 

for those compounds that were detected above plan 

initiation levels (PILs) determined as part of this 

process.

All samples for this study were collected using 

standard methods described by U.S. Geological 

Survey (USGS; variously dated). Samples were 

placed into glass or Teflon® bottles depending 

on the type of analysis, and then composited into 

either a glass carboy or Teflon churn for processing. 

Samples were collected at most of the WWTPs 

in December 2008, but samples were collected in 

St. Helens and Longview in December 2009 because they were added 

later in the project (table 4). Wenatchee was resampled in 2009 due to 

sampling errors with the filtration apparatus in 2008 that compromised 

some of the analyses. The stormwater samples were collected 

throughout spring and winter storms of 2009 and 2010. 

Samples were placed on ice until they could be processed and 

shipped to the appropriate laboratory; most samples were shipped in 

less than 3 hours. Volunteers were used to collect stormwater samples 

in remote locations. These samples were shipped to the USGS Oregon 

Water Science Center before they were processed, resulting in a 

holding time of about 40 hours or less. While the sample was being 

mixed (required to resuspend any settled solids), unfiltered‐water 

samples were drained into their respective bottles. For filtered-water 

analyses, aliquots of the sample were filtered through a 142‐mm 

diameter, 0.7-μm pore-size glass-fiber filter and collected into amber 

glass bottles to be sent to the USGS National Water-Quality Laboratory 

(NWQL) in Denver, Colorado. 

Stormwater-runoff sample in 20-liter glass carboy, collected from a pipe under the I-5 

bridge on Hayden Island, Oregon, October 2009.
8 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Table 4. Summary of sampling activities, Columbia River Basin, Washington and Oregon, 2008–10.

[Station names are shown in tables 2 and 3. Constituents analyzed, reporting limits, and method parameters are presented in appendix A]

City or 

short name Date Time Suspended 

sediment

Anthropogenic 

organic 

compounds 

in unfiltered 

water 

(table A2)

Pharmaceuticals 

in filtered 

water 

(table A3)

Halogenated 

compounds 

on solids 

filtered from 

samples 

(table A1)

Currently 

used 

pesticides 

in filtered 

water 

(table A4)

Mercury 

and methylmercury in 

unfiltered 

water

Polycyclic 

aromatic 

hydrocarbons 

in unfiltered 

water 

(table A5)

Trace 

elements in 

unfiltered 

and filtered 

water 

(table A6)

Oil and 

grease in 

unfiltered 

water

Wastewater-treatment-plant effluent samples

2008 visit to initial seven cities

Wenatchee 12-02-08 1010 X X X X

Richland 12-04-08 0900 X X X X

Umatilla 12-03-08 0840 X X X X

The Dalles 12-05-08 0830 X X X X

Hood River 12-10-08 0950 X X X X

Portland (a.m.) 12-09-08 0900 X X X X

 (noon) 12-09-08 1150 X X X X

 (p.m.) 12-09-08 1500 X X X X

Vancouver 12-08-08 0940 X X X X

2009 revisit and additional cities

Wenatchee 12-01-09 0850 X X X X X X

Richland 12-02-09 0820 X X

Umatilla 12-02-09 0950 X X

The Dalles 12-02-09 1200 X X

Hood River 12-02-09 1310 X X

Portland 12-10-09 0840 X X

Vancouver 12-02-09 1510 X X

St. Helens 12-03-09 0900 X X X X X X

Longview 12-08-09 0810 X X X X X X

Stormwater-runoff samples

2009 and 2010 storms

Wenatchee 12-21-09 1340 X X X X X X X

Richland 05-02-09 1200 X X X X X X

Umatilla 10-04-09 0920 X X X X X X

The Dalles 02-23-09 1210 X X X X X X

Hood River 02-23-09 1310 X X X X X X

Portland1 10-14-09 1100 X X X X X X

Portland2 10-26-09 1210 X X X X X X

Vancouver1 12-16-09 1340 X X X X X X X

Vancouver2 12-16-09 1210 X X X X X X X

Willamette1 06-04-10 0840 X X X X X X X

Willamette2–Dec 12-15-09 1330 X X X X X X X

Willamette2–May 05-26-10 1310 X X X X X X X

Willamette3 12-15-09 1310 X X X X X X X

Willamette4 05-26-10 1410 X X X X X X X

St. Helens 03-30-10 1310 X X X X X X X

Longview 03-30-10 1410 X X X X X X X
Sampling Design and Methods 9

Analytical Methods for WastewaterTreatment-Plant-Effluent Samples

A full listing of all constituents analyzed, 

reporting limits, and method numbers is presented 

in appendix A. Because halogenated compounds 

like flame retardants, PCBs, and certain pesticides 

(table A1) are hydrophobic (preferentially associated 

with sediment particles), solid samples were 

collected for analysis. Because WWTP effluent 

is low in solids by design, about 20 liters (L) 

of effluent were filtered for each WWTP. These 

filters were sent to the NWQL for the analysis of 

halogenated compounds on the filtered solids. These 

analyses were done as an adaptation to the method 

used for analyzing these compounds in sediments 

(Steven Zaugg, National Water-Quality Laboratory, 

written commun., March 16, 2010), which involved 

extracting all material collected on the filters and 

concentrating it down to 1 mL of extract, which 

was analyzed for the entire suite of halogenated 

compounds. These concentrations, therefore, provide 

a measure of the hydrophobic compounds detected 

in the particulate phase and do not account for 

compounds present in the dissolved phase. 

For the WWTP-effluent samples, AOCs in 

unfiltered water (table A2) were analyzed at the 

NWQL by continuous liquid-liquid extraction 

and gas chromatography/mass spectrometry (GC/

MS) using methods described by Zaugg and 

others (2006). Human-health pharmaceuticals 

(table A3) and currently used pesticides (table A4) 

in filtered‐water samples were analyzed at NWQL 

by GC/MS using methods detailed by Zaugg and 

others (1995), Lindley and others (1996), Sandstrom 

and others (2001), Madsen and others (2003), 

and Furlong and others (2008). In 2009 and 2010, 

unfiltered water samples were preserved with 

hydrochloric acid and sent to the USGS Wisconsin 

Mercury Research Laboratory for the analysis 

of total mercury and methylmercury by methods 

described by U.S. Environmental Protection Agency 

(2002) and DeWild and others (2002), respectively. 

Suspended-sediment concentrations were 

determined at the Cascades Volcano Observatory 

Sediment Laboratory in Vancouver, Washington, 

according to methods detailed by Guy (1969).

For samples collected at each city in 2008, 

a 1-L unfiltered WWTP-effluent sample was 

shipped on ice to the Columbia Environmental 

Research Center (CERC) in Columbia, Missouri, 

to be screened for total estrogenicity using the yeast estrogen screen 

(YES) by methods described by David Alvarez (U.S. Geological 

Survey, written commun., November 6, 2009). The YES assay uses 

recombinant yeast cells with a human estrogen receptor. If these cells 

bind to an estrogen or estrogen-mimic in the sample, then a number of 

biochemical reactions occur and result in a color change (Routledge 

and Sumpter, 1996; Rastall and others, 2004). This color change can 

be measured spectrophotometrically and the estradiol equivalent factor 

(EEQ) for the sample can be determined. The EEQ is an estimate 

of the amount of 17β-estradiol, a natural hormone, which would be 

needed to give an equivalent response to that of the complex mixture 

of chemicals present in the sample (Rastall and others, 2004; Alvarez 

and others, 2008). Therefore, a higher measured EEQ indicates a higher 

estrogenicity of the sample. 

Filtering wastewater-treatment-plant effluent from the City of Portland, Oregon, 

December 2008.
10 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Analytical Methods for 

Stormwater-Runoff Samples

Halogenated compounds on solids, currently 

used pesticides in filtered water, mercury and 

methylmercury in unfiltered water, and suspendedsediment samples collected from the stormwater 

runoff were processed in the same way as described 

for the WWTP-effluent samples. Additionally, 

stormwater-runoff samples were collected for the 

analysis of PAHs in unfiltered water (table A5) 

and trace elements in both filtered and unfiltered 

water (table A6). These samples were analyzed at 

the NWQL by methods described by Fishman and 

Friedman, (1989), Fishman (1993), Hoffman and 

others (1996), Garbarino and Struveski (1998), 

Garbarino and Damrau (2001), and Garbarino 

and others (2006). Unfiltered‐water samples 

were subsampled into bottles with sulfuric acid 

preservative and shipped on ice to the TestAmerica 

Laboratory in Arvada, Colo., for analysis of oil and 

grease by EPA method 1664A (U.S. Environmental 

Protection Agency, 1999). 

Reporting of Data

When an analyte is measured in a laboratory, 

it is either detected or not detected. When it is not 

detected, it is reported as “censored” or less than the 

reporting limit (RL). This does not mean that the 

analyte is not present; it simply means that it could 

not be detected in a sample under the conditions 

present in the laboratory or the sample matrix. The 

analyte may be present, but at a concentration lower 

than the instrument can measure. Likewise, the 

presence of other material or analytes in the sample 

may be causing interference, preventing the accurate 

quantification of the analyte in the sample, or the 

analyte may not be present at all. If, however, the 

analyte is detected, it may be reported in several 

different ways. If it is detected at a concentration 

greater than the RL, then the value is simply reported 

at the concentration measured. If the analyte is a 

“poor performer” (long-term variability or poor 

recovery) in laboratory performance samples or if 

matrix problems caused interference for that analyte 

in the sample, the measured concentration may be 

qualified as an estimated (E) value. 

The concentration also may be reported as 

an estimated value if the analyte is detected at a 

concentration less than the RL but greater than 

the method detection limit (MDL). The MDL is a 

statistically derived minimum concentration that 

can be measured with a 99 percent confidence of 

being greater than zero (Oblinger Childress and 

Filter paper after filtering stormwater-runoff sample from the City of Umatilla, Oregon, 

October 2009.

others, 1999; Bonn, 2008). Therefore, there is a less than a 1 percent 

chance that an analyte will be reported as a false positive, or that the 

concentration was reported but the analyte was not present. If the 

analyte is detected at a concentration less than the MDL or RL (for 

those analytes for which a MDL has not yet been established), then, 

in this report, the result is reported as “Present,” indicating that the 

presence of the analyte was verified, but that the concentration was 

too small to be quantified. The NWQL reevaluates the RL and MDL 

values every year and adjusts them as needed based on the laboratory 

performance data. Because of these adjustments, multiple RLs may 

be shown for a given analyte. Additionally, matrix interference issues, 

which were numerous in this study due to the complex nature of the 

effluent and runoff, can cause the RL for a certain compound for 

individual samples to be raised as well. 

The data for the halogenated compounds on solids were reported 

from the NWQL as the mass of the given analyte detected in the sample 

(in nanograms). This mass was then divided by the number of liters 

filtered, to obtain a concentration of the analyte for the sample (in 

nanograms per liter, ng/L). Detections for this analysis were reported 

only if the mass was greater than the RL or five times the highest value 

reported in the laboratory blank, trip blank, or analyses of the filter 

papers themselves. Detections less than these levels were reported as 

“Present.” 

Quality Assurance

Quality assurance is the analysis of quality-control (QC) data as 

a means to assess potential contamination and variability associated 

with sampling and laboratory techniques. Quality control samples for 

this study comprised field blanks and replicate environmental samples 

(table 5), as well as internal laboratory QC data such as set blanks, 

set spikes, and surrogate recoveries. Between 1 and 3 blanks and 2 

and 4 replicates were collected for each analytical method. For some 
Sampling Design and Methods 11

Table 5. Summary of quality-control (QC) analyses performed for this study, Columbia River Basin, Washington and Oregon, 2008–10.

[Station names are shown in tables 2 and 3]

City or 

short name Date

Type of 

qualitycontrol 

sample

Suspended 

sediment

Anthropogenic 

organic 

compounds 

in unfiltered 

water 

Pharmaceuticals 

in filtered 

water

Halogenated 

compounds 

on solids 

filtered from 

samples

Currently 

used 

pesticides

in filtered 

water

Mercury 

and methylmercury in 

unfiltered 

water

Polycyclic 

aromatic 

hydrocarbons 

in unfiltered 

water

Trace 

elements in 

unfiltered 

and filtered 

water

Oil and 

grease in 

unfiltered 

water

Wastewater-treatment-plant effluent samples

2008 visit to initial seven cities

Umatilla 12-03-08 Blank X X X X1

Vancouver 12-08-08 Replicate X X X X

2009 revisit and additional cities

Umatilla 12-02-09 Blank X

Vancouver 12-02-09 Replicate X X

St Helens 12-03-09 Replicate X X X X X X

Stormwater-runoff samples

2009 and 2010 storms

Wenatchee 12-21-09 Replicate X X X X X X X

The Dalles 02-23-09 Blank X X X X X

Portland2 10-26-09 Replicate X X X X X X

Willamette1 06-07-10 Blank X X X X X X X

1

 Filter papers were analyzed instead of a field blank for this method.

combinations of method and sample type (currently used 

pesticides in WWTP samples), no blanks were collected, 

although for most combinations, one blank and two replicates 

were collected. QC samples were collected throughout the 

sampling periods to assess any annual variability in laboratory 

performance. Results of all of these QC samples were used to 

qualify the environmental data. 

Field blanks were collected by passing a volume of 

contaminant-free water (organic blank water) through 

sampling and processing equipment that an environmental 

sample would contact. The results of field blanks are used 

to assess contamination issues associated with cleaning, 

sampling, processing, or transporting the sample. In addition 

to a field blank for the halogenated compounds on solids, the 

filter papers themselves were run through the process to assess 

whether they may be affecting the analysis. 

Replicate environmental samples test for precision, which 

is a measure of the variability between two or more samples 

caused by variability in laboratory processing techniques and 

measurement precision. Replicate samples were collected 

consecutively, except for the stormwater sample collected at 

Portland2. That sample was collected into one glass carboy, 

agitated to resuspend solids, and then split in the laboratory 

during processing. 

“Surrogate compounds” have properties similar to those 

of the target compounds; surrogate compounds are added to 

the sample at the laboratory and analyzed as part of the list 

of analytes. Surrogate compounds are expected to behave 

similarly to the target analytes and are used to monitor the 

performance of the method used for the target analytes 

they represent. The NWQL uses the surrogate recoveries to 

assess problems associated with individual samples or sets 

of samples, but also uses long-term surrogate recoveries to 

assess long-term analytical precision. Surrogate recoveries 

in this study were good for blank samples but generally low 

for environmental samples (table 6). This was probably due 

to matrix-interference issues. The actual concentrations in 

the samples may have been underestimated by the analyses; 

therefore, this report represents a conservative measure of the 

contaminants delivered by WWTP effluent and stormwater 

runoff. Because of the large variations in sample recoveries 

and sample performance, care should be used in drawing 

comparisons between sample sets. Although the validity 

of quantitative comparisons may be compromised by this 

variability, qualitative analyses, based on the presence or 

absence of these compounds, provide a way to compare these 

types of datasets. 
12 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 Table 6. Summary of surrogate recoveries, Columbia River Basin, Washington and Oregon, 2008–10. [Station names are shown in tables 2 and 3. Values reported in percent. Abbreviatons: ND, not determined because of matrix interferences or sample preparation errors; E, estimated; HCH, hexachlorocyclohexane; DDT, dichlorodiphenyltrichloroethane; PCB, polychlorinated biphenyl; NA, not analyzed, for example, currently used pesticides were not analyzed in 2008] Wastewater-treatment-plant effluent samples Surrogate analyte Wenatchee Richland Umatilla The Dalles Hood River Portland Vancouver St. Helens Longview Blank (2008) (2009) (a.m.) (noon) (p.m.) (2009) Anthropogenic organic compounds in unfiltered water Bisphenol A-d3 87 89 38 94 0 18 31 37 ND NA 0 94 89 88 Caffeine-c13 84 65 21 97 66 79 91 94 62 NA 36 80 75 89 Decafluoro- biphenyl 58 56 26 84 59 66 56 61 48 NA 30 51 61 76 Fluoranthene-d10 65 67 37 90 61 75 62 64 47 NA 28 63 68 89 Pharmaceuticals in filtered water Carbamaz- epine-d10 17 22 27 20 13 23 11 8 10 NA 12 29 15 106 Ethyl nicotinate-d4 E 138 65 E 100 E 90 E 101 114 73 81 53 NA 83 54 39 E 134 Currently used pesticides in filtered water Diazinon-d10 NA 138 E 109 E 105 E 104 E 113 NA NA NA 132 E 108 117 116 NA alpha-HCH-d6 NA ND ND ND ND ND NA NA NA 81 ND 102 88 NA Halogenated compounds on solids DDT-d8 NA 5 24 42 31 15 35 20 54 NA 18 12 34 64 Dibromo- octafluoro- biphenyl NA 5 61 63 62 54 65 34 66 NA 56 12 25 53 PCB-202-13C12 NA 4 34 53 43 35 31 22 50 NA 32 7 13 67
Sampling Design and Methods 13

Stormwater-runoff samples

Surrogate analyte Wenatchee Richland Umatilla The Dalles Hood River Portland1 Vancouver1 Vancouver2 Portland2 Willamette1 Willamette2 Willamette3 Willamette4 St. Helens Longview Blank– Hood River Blank– Willamette1 –Dec –May

Currently used pesticides in filtered water

Diazinon-d10 114 E 153 138 134 125 153 108 105 134 116 126 125 109 116 98 120 100 103alpha-HCH-d6 80 91 79 97 93 84 92 90 105 92 81 102 91 96 99 99 87 96

Polycyclic aromatic hydrocarbons (PAHs) in unfiltered water

2-Fluoro-biphenyl 70 84 63 52 93 63 73 73 46 80 73 64 77 63 33 67 87 892-Fluoro-phenol 66 78 71 23 37 62 64 61 28 79 59 57 74 43 20 54 54 49Nitrobenzene-d5 103 94 97 57 97 94 85 88 53 102 88 83 90 74 38 79 92 95Phenol-d5 52 57 58 9 32 58 52 48 28 60 49 57 65 31 19 46 45 37

Terphenyl-d14 45 64 37 34 84 35 55 45 30 49 55 34 52 41 34 52 88 872,4,6-Tribromophenol 91 113 94 38 47 93 90 93 61 108 102 95 103 73 23 76 63 54

Halogenated compounds on solids

DDT-d8 75 43 46 29 54 14 3 4 74 83 9 83 7 81 97 33 NA 82Dibromooctafluorobiphenyl 62 82 25 45 29 20 3 4 30 52 7 66 7 38 104 23 NA 77PCB-202-13C12 65 47 19 34 51 7 1 2 40 67 6 65 5 70 65 21 NA 53

Table 6. Summary of surrogate recoveries, Columbia River Basin, Washington and Oregon, 2008–10.—Continued[Station names are shown in tables 2 and 3. Values reported in percent. Abbreviatons: ND, not determined because of matrix interferences or sample preparation errors; E, estimated; HCH, 

hexachlorocyclohexane; DDT, dichlorodiphenyltrichloroethane; PCB, polychlorinated biphenyl; NA, not analyzed, for example, currently used pesticides were not analyzed in 2008]
14 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Table 7. Summary of detections in blank samples, Columbia River Basin, Washington and Oregon, 2008–10.

[No detections in blanks for pharmaceuticals. Raised reporting limits were used to further qualify the environmental data—detections less 

than raised reporting limit have been reported as “Present.” Abbreviations: E, estimated; PBDE, polybrominated diphenyl ether; PCB, 

polychlorinated biphenyl]

Compound detected 

in blank

Highest value 

in blank

Raised reporting limit 

(5 * blank value)

Lowest detected 

concentration

Anthropogenic organic compounds in unfiltered water, in micrograms per liter (field blank)

Cholesterol E 0.62 3.1 E 0.8

3-beta-Coprostanol E 0.58 2.9 E 0.63

4-Nonylphenol monoethoxylate (sum of all isomers) [NP1EO] E 0.22 1.1 E 0.32

para-Nonylphenol (total) E 0.42 2.1 E 0.4

Phenol E 0.19 0.95 E 0.18

Halogenated compounds on solids, in nanograms (field, filter, and set blanks)

Dechlorane plus 0.21 1.1 0.19

Hexachlorobenzene (HCB) 0.22 1.1 1.0

PBDE-47 2.7 14 22

PBDE-99 0.84 4.2 2

PBDE-100 0.25 1.3 0.54

PCB-194 0.11 0.55 0.06

Pentachloroanisole 0.11 0.55 0.09

Triclosan 8.4 42 6.2

Polycyclic aromatic hydrocarbons (PAHs), in micrograms per liter (field blanks)

1,4-Dichlorobenzene E 0.014 0.07 E 0.015

Diethyl phthalate E 0.155 0.78 E 0.22

Dimethyl phthalate E 0.029 0.15 E 0.016

Trace elements in unfiltered and filtered water, in micrograms per liter (field blanks)

Lead in unfiltered water E 0.053 0.27 0.18

Chromium in filtered water E 0.084 0.42 E 0.075

Mercury and methylmercury in unfiltered water, in nanograms per liter (field blanks)

Total mercury in unfiltered water 0.24 1.2 1.9

Results of Quality-Control Data

There were only a few analytes with detections in the 

field blanks (table 7), and most were not at levels that warrant 

concern with respect to the environmental detections. For 

those compounds with detections in a blank sample (a field, 

filter, or set blank), the highest detected value in the blank was 

multiplied by five and this new value was used as a “raised 

reporting level.” If a detected concentration was less than this 

raised reporting level, then it was reported as “Present,” rather 

than the actual concentration. 
Sampling Design and Methods 15

Table 8. Summary of relative percent differences for replicate samples, Columbia River Basin, Washington and Oregon, 2008–10.

[Each analytical schedule and sample type had two replicate pairs except for mercury in stormwater runoff, which had only one replicate pair. Abbreviations:

LC, laboratory code; SH, schedule; Storm, stormwater runoff; WWTP, wastewater-treatment-plant effluent; –, not applicable]

Analytical

No.

Compound group 

description

Sample

type

Number of 

compounds

analyzed 

Number of 

compounds 

detected in 

replicate 

pair #1

Number of 

compounds 

detected in 

replicate 

pair #2

Relative percent difference

Minimum Median Maximum

SH 4433 Anthropogenic organic compounds WWTP 69 20, 22 34, 33 0 39 101

SH 2080 Pharmaceuticals WWTP 14 6, 7 7,7 0 13 74

LC 8093 Halogenated compounds WWTP 60 19, 20 17, 23 0 23 56

LC 8093 Halogenated compounds Storm 60 3,1 15, 9 0 42 88

SH 2033 Currently used pesticides WWTP 83 6, 6 6, 6 0 4 30

SH 2033 Currently used pesticides Storm 83 7, 7 2, 3 0 6 21

– Mercury and methylmercury WWTP 2 2, 2 2, 2 2 25 40

– Mercury and methylmercury Storm 2 2, 2 – 2 – 12

SH 1383 Polycyclic aromatic hydrocarbons Storm 56 8, 8 22, 25 0 17 58

SH 1264 Trace elements in filtered water Storm 10 8, 8 8, 8 0 4 92

SH 1264 Trace elements in unfiltered water Storm 10 7, 7 9, 8 0 4 92

Method blanks for the oil and grease analyses showed 

consistent and significant detections. Nearly one-half of the 

method-blank samples had detectable concentrations equal 

to at least one-half of the coinciding environmental-sample 

concentration. The environmental and blank results are 

reported together so that the user is aware of these issues (see 

section “Oil and Grease”).

When comparing differences in concentrations 

from different sites or different times, the analytical and 

environmental variability must be considered. Examining 

environmental replicate data can help quantify this variability. 

Relative percent difference (RPD) values, which provide a 

measure of how well the concentrations from two samples 

agree, were calculated for all environmental replicate 

data pairs (table 8). The RPD is calculated as the absolute 

difference between two values, normalized to the average 

value, and expressed as a percentage.

( )

( )

1 2

100.

1 2 / 2

Value Value

RPD

Value Value

− ≡ × +

An RPD close to zero shows good agreement between the 

sample results, but some RPDs in this study are high. This 

probably is due to a number of variables, including methods 

used to analyze unfiltered water, low concentrations in 

samples, and the inherent variability in some of the methods, 

which may be linked to matrix effects.
16 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Compound Classes

Several compound classes were analyzed in this study. A 

brief description of each is provided here to give an overview 

of what type of contaminants are in each class, potential 

sources of each class, and documented effects of some of 

these contaminants.

Anthropogenic Organic Compounds

Anthropogenic organic compounds are a broad suite 

of compounds that are typically associated with human, 

industrial, and agricultural wastewater and include 

detergent metabolites, flame retardants, personal care 

products, pesticides, plasticizers, PAHs, steroids, and other 

miscellaneous compounds. Although these compounds are 

associated with wastewater, it is important to note that the 

WWTP is not the source of these compounds, but simply a 

pathway by which these compounds can reach the ecosystem 

from urban environments. 

Besides WWTP effluent, these compounds also can 

reach streams from runoff from land applications, industrial 

facilities, animal feed lots, and septic systems. In 1999–2000, 

139 streams were sampled in 30 states across the United 

States, and AOCs were detected in 80 percent of the streams 

sampled with as many as 38 compounds in one sample 

(Kolpin and others, 2002). Some of these compounds 

bioaccumulate in biota and many are suspected or known 

endocrine disruptors, meaning they mimic hormones and 

can cause problems with the endocrine system, which affects 

reproduction and growth. Detergent metabolites nonylphenol 

and fragrances like tonalide and galaxolide have been shown 

to cause endocrine issues in fish (Schreurs and others, 

2004), and the antimicrobial disinfectant triclosan can result 

in reduced algal diversity (Wilson and others, 2003) and 

increases antibiotic resistance (Sprague and Battaglin, 2005). 

Pharmaceuticals

More than 3.9 billion prescription drugs are purchased 

annually in the United States, and the average American 

takes more than 12 prescription drugs each year (Kaiser 

Family Foundation, 2010). Fifty to 90 percent of the active 

ingredients in these pharmaceuticals passes through the 

body and is excreted as either the parent compound or its 

metabolites (Lubliner and others, 2008). From there, these 

pharmaceuticals enter the wastewater stream, to either a 

WWTP or a septic system. Besides excretion, the other main 

path to the environment for pharmaceuticals is disposal. It was 

once recommended that consumers dispose of pharmaceuticals 

through either their drain or toilet, but this outdated practice 

is now discouraged in an effort to reduce the amount of 

these compounds travelling to the WWTP. Many states 

are trying to develop drug take-back programs, but federal 

narcotic regulations complicate the process. In the meantime, 

consumers are asked to mix unused pharmaceuticals with 

coffee grounds or kitty litter and dispose of them in the trash. 

Residential homes, long-term care facilities, health‐care 

facilities such as hospitals, and veterinary clinics are current 

sources for pharmaceuticals reaching the environment 

(Hubbard, 2007), but landfill leachates and garbage-incinerator 

emissions may be emerging sources as society tries to deal 

with the disposal issue. Most of these sources use WWTPs 

as the pathway for reaching the receiving waters. Removal of 

this class of compounds from the waste stream is complicated 

by the varying chemical nature of the compounds. Typical 

treatment techniques used by WWTPs remove some of 

these pharmaceuticals but are ineffective on others, such as 

carbamazepine. The amount of pharmaceuticals entering the 

environment may be reduced by consumers who use fewer 

pharmaceuticals or select “greener” options (Lubick, 2010), 

and by proper disposal of pharmaceuticals.

Pharmaceuticals, by intent, are biologically active, 

therefore, although their exact effects on wildlife are not 

yet fully documented, their presence in the environment 

would be expected to have adverse ecological effects 

(Williams, 2005). Pharmaceuticals and other contaminants 

delivered through WWTP effluent can be considered to 

have “pseudo-persistence” because of the continual input of 

these compounds (Smital, 2008). The effects of continuous 

low‐level exposure to these pharmaceuticals, particularly 

during sensitive life stages, as well as long-term exposure to 

the complex mixtures in these effluents are further unknowns 

(Daughton and Ternes, 1999). 

Halogenated Compounds

Polybrominated diphenyl ethers (PBDEs) are man‐made 

chemicals used as flame retardants in electronics, building 

materials, seat cushions, and clothing. PCBs are stable, 

nonflammable chemicals used as insulators and cooling 

compounds in electric equipment and have been used in 

other products like paint, inks, and pesticides. PCBs and 

PBDEs have similar structures and are similar toxicologically, 

causing problems in marine and freshwater fish ranging 

from neurotoxicity to hormone disruption (Lower Columbia 

River Estuary Partnership, 2007). A recent study found 
Compound Classes 17

that exposure to PBDEs was associated with depressed 

levels of thyroid-stimulating hormone in pregnant women, 

the health implications of which are unknown (Chevrier 

and others, 2010). Both PCBs and PBDES are persistent, 

hydrophobic compounds that do not degrade or dissolve 

readily in water and tend to bioaccumulate in fatty tissues 

and have been detected in soil, air, water, sediment, and 

bodies of fish, wildlife, and people. Johnson and others 

(2007) measured PCBs in the tissue of juvenile salmon from 

the lower Columbia River downstream of the industrial and 

urban Portland/Vancouver area at concentrations exceeding 

adverse‐effects thresholds. Recently, PBDEs have been 

detected in multiple arctic species (Arctic Monitoring and 

Assessment Programme and Arctic Council Action Plan 

to Eliminate Pollution of the Arctic, 2005), illustrating the 

ubiquitous nature of these halogenated compounds.

Currently Used Pesticides

Currently used pesticides include herbicides and 

insecticides that often can be found in any home or garage 

and are used for pest control (flea medicine for pets often 

contains fipronil), garden care (household insect spray often 

contains pyrethroids such as permethrin), or general weed 

maintenance (Casoron® contains dichlobenil and Pendulum®

contains pendimethalin). Although pesticides often are 

discussed as a pollutant of concern in agricultural areas, 

urban areas can be a source as well because of residential use, 

commercial-landscape use, and road maintenance. 

Organophosphates and carbamates have been shown 

to have sublethal effects on salmon, causing problems with 

olfaction, homing, and predator avoidance (Sandahl and 

others, 2007). Pesticides are rarely detected alone and often 

occur in the environment in mixtures. Mixtures of pesticides 

can have an additive or synergistic effect when they are 

together in the environment (Lower Columbia River Estuary 

Partnership, 2007). Laetz and others (2009) determined that 

mixtures of diazinon, chlorpyrifos, malathion, carbaryl, 

and carbofuran—the most extensively used pesticides in 

California and the Pacific Northwest—significantly inhibit 

acetylcholinesterase activity more when they are present 

together than when they are present individually. This 

acetylcholinesterase inhibition can interfere with survival 

behaviors and essential reactions to stimuli; therefore, the 

presence of these mixtures may be affecting salmon recovery 

more than expected. 

Polycyclic Aromatic Hydrocarbons

PAHs are persistent, widespread organic contaminants 

that are in petroleum products, creosote-treated wood, paints 

and dyes, or are created through incomplete combustion 

(Lower Columbia River Estuary Partnership, 2007). PAHs 

tend to adsorb to sediments, which can then act as reservoirs 

for future transport. Benthic invertebrates living in this 

sediment can bioaccumulate PAHs and pass them on to 

their predators. In vertebrates, like fish, however, PAHs do 

not bioaccumulate but are metabolized, and some PAHs are 

known or suspected carcinogens for vertebrates (Johnson and 

others, 2002). Parking lots treated with coal-tar-based sealcoat 

have been shown to be a major source of PAHs (VanMetre 

and others, 2009); therefore, stormwater passing over these 

surfaces can transport PAHs to the receiving streams. 

Trace Elements and Mercury

Trace elements are metals and other natural chemicals 

that can be toxic even at low concentrations and aquatic biota 

have little need for them. For this report, these compounds 

include arsenic, cadmium, chromium, copper, lead, nickel, 

selenium, silver, and zinc. Although trace elements are 

naturally occurring, they also can be introduced through 

industrial uses and motor vehicles. For instance, copper and 

zinc are contributed to roads and other impervious services 

from brake pads, tires, and vehicle exhaust (Davis and others, 

2001), and then stormwater runoff transports these deposits 

to its receiving waters (Sandahl and others, 2007). Copper 

has been shown to have sublethal effects on salmon behavior 

through effects on olfaction even at water concentrations 

as low as 2 μg/L (Baldwin and others, 2003). Another 

commonly detected trace element, cadmium, bioaccumulates 

in reproductive organs of fish and disrupts important endocrine 

processes, especially those involved in synthesis, release and 

metabolism of hormones (Tilton and others, 2003). 

Mercury in the environment is never destroyed but 

simply cycles between chemical and physical forms. In 

the aquatic environment, mercury is converted to a more 

toxic form, methylmercury, which is most often detected 

in fish. Methylmercury is a known neurotoxin and studies 

have shown that environmentally realistic concentrations 

of methylmercury can impair the reproductive cycle in fish 

(Drevnick and Sandheinrich, 2003). 
18 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Contaminant Concentrations in 

Wastewater-Treatment-Plant 

Effluent

Anthropogenic Organic Compounds

Anthropogenic organic compounds were 

measured at each WWTP (table 9), but an obvious 

pattern based on population (table 1) did not emerge 

from the results. For instance, it might be expected 

that a larger number of compounds may be detected 

at larger population centers with a smaller number 

of detections occurring at smaller population 

centers. If this were true, large differences may 

be expected between the results for Umatilla 

(roughly 5,000 people) and for Portland (roughly 

500,000 people), but this is not often the case. The 

data indicate that there are many more variables 

(for instance treatment technology) affecting the 

presence and concentration patterns than simply 

population. Flame retardants and steroids were 

consistently detected in all WWTP‐effluent 

samples, although few pesticides or PAHs were 

detected, except at Longview. Longview also 

was notable because it had the greatest number 

of detections and the concentrations were usually 

among the highest, particularly for the personalcare-product compounds. 

The compounds at all WWTPs (table 9) were 

two flame retardants [tri(2chloroethyl)] phosphate 

and tri(dichloroisopropyl)phosphate), a fixative 

often included in sunscreen (benzophenone), a 

suspected endocrine disruptor used as a fumigant 

(1,4-dichlorobenzene), an extensively used musk 

(galaxolide), two fecal indicators (cholesterol 

and 3-beta-coprostanol), and a plant sterol (betasitosterol). Compounds also found in all samples 

except those collected in Umatilla included 

a known endocrine disrupter and detergent 

metabolite (NP2EO), another flame retardant 

(tributyl phosphate), another extensively used musk 

(tonalide), a common ingredient in cosmetics and 

pharmaceuticals (triethyl citrate), and a plasticizer 

(triphenyl phosphate). The effluent from all cities 

except Richland contained a popular stimulant 

(caffeine) and a suspected endocrine disruptor and 

disinfectant used in most hand soaps (triclosan). 

These examples show the variety and prevalence of 

these compounds in WWTP effluent. 

Many of these compounds are somewhat hydrophobic, indicating 

that they prefer to be associated with sediment or solids rather than the 

water phase. Observing the amount of these compounds transported in 

the unfiltered effluent raises questions about what types of compounds 

may be detected in the biosolids generated by the WWTPs, and at what 

concentrations. Kinney and others (2006) surveyed biosolids destined 

for land application from 9 cities across the United States and detected 

25 AOCs present. All of these compounds also were found in this study, 

except fluoxetine, which was not measured, indicating that biosolids 

may be a source of contamination that can be studied in the future 

in the Columbia River Basin (Oregon Department of Environmental 

Quality, 2011). 

Effluent stream past ultraviolet disinfection at the City of Hood River WastewaterTreatment Plant, Oregon, December 2008. 
Contaminant Concentrations in Wastewater-Treatment-Plant Effluent 19

Table 9. Anthropogenic organic compounds detected in unfiltered wastewater-treatment-plant effluent, Columbia River Basin, Washington and Oregon, 2008–09.[Station names are shown in table 2. Concentrations reported in micrograms per liter. See table A2 for a listing of anthropogenic organic compounds analyzed and their reporting limits. Present, 

presence is verified, but concentration is not quantified; sometimes the reporting limit for an individual sample is raised because of matrix interference, these instances of non-detection are shown as less-than (<) the raised reporting limit. Abbreviations: ND, not determined because of matrix interferences; E, estimated; –, not detected]

Analyte

Wenatchee

Richland Umatilla The Dalles Hood River 

Portland

Vancouver St. Helens Longview

(2008) (2009) (a.m.) (noon) (p.m.)

Detergent metabolites

4-Cumylphenol Present – – – – – – – – – – –para-Nonylphenol (total) Present – Present – – Present Present Present Present – E 2.7 Present

4-Nonylphenol monoethoxylate

 (sum of all isomers) [NP1EO]

< 2.0 – Present < 2.0 Present Present E 5.8 E 6.3 E 4.4 Present Present –

4-Nonylphenol diethoxylate 

 (sum of all isomers) [NP2EO]

E 2.2 E 1.5 E 2.6 – E 3.8 E 2.1 E 14 E 13 E 9.3 Present E 1.3 E 1.7

4-tert-Octylphenol – Present – – – – – – – – E 0.21 E 0.16

4-tert-Octylphenol diethoxylate (OP2EO) < 0.78 E 0.37 – – E 1.0 E 0.32 E 1.3 E 1.2 E 0.90 E 0.38 E 0.31 E 0.85

4-tert-Octylphenol monoethoxylate (OP1EO) – Present – – E 0.80 – E 0.90 E 0.84 E 0.81 – – E 0.55

Flame retardants

Tri(2-butoxyethyl)phosphate E 0.74 E 0.42 – – E 3.4 E 0.54 E 2.4 E 1.9 E 2.3 E 1.1 E 2.2 E 1.9

Tri(2-chloroethyl)phosphate 0.65 0.44 E 0.15 0.46 0.26 0.45 0.41 0.41 0.3 E 0.16 Present 0.3

Tri(dichloroisopropyl)phosphate 0.64 0.69 E 0.18 0.39 0.43 0.52 0.39 0.45 0.32 E 0.28 E 0.12 0.33

Tributyl phosphate Present 0.2 Present – Present Present E 0.60 E 0.38 Present Present 0.33 0.42

Miscellaneous—antioxidants, solvents, or multiple uses

Anthraquinone – – – Present – – – – 0.22 – E 0.15 –

Bromoform – – Present – Present – – – – – – –

3-tert-Butyl-4-hydroxyanisole (BHA) – Present – – – – – – – – – –

Caffeine E 0.073 Present – Present E 0.076 0.28 1.6 0.92 1.2 Present 7 20

Cotinine – – – – Present – Present – Present – Present E 0.34

para-Cresol – Present – 0.25 – – – – – – Present E 0.12

Isophorone – – – – – – – Present Present – – –

Isopropylbenzene (cumene) – – – – – – – – – – – E 0.032

d-Limonene – – – – – – – – – – – E 0.078

5-Methyl-1H-benzotriazole E 0.59 Present E 0.36 – E 0.52 E 0.80 E 0.74 E 0.62 E 0.62 E 0.57 – E 0.89

Pentachlorophenol E 0.89 Present – – – – E 0.79 E 0.77 – – Present Present

Tetrachloroethylene – Present Present – Present – Present Present Present – – Present

Personal care products

Acetophenone – E 0.14 – – – – – – – – – E 0.34

Benzophenone 0.27 0.24 Present Present 0.26 0.2 0.28 0.26 0.22 E 0.10 E 0.19 0.30

Camphor – – – – – – – – – – Present 1.31,4-Dichlorobenzene E 0.26 0.33 Present E 0.04 E 0.40 E 0.24 E 0.40 E 0.42 E 0.41 E 0.10 Present 0.88

Galaxolide 1.5 2.5 E 1.5 1.3 1.2 1.1 1.0 1.2 0.97 E 1.2 0.38 1.2
20 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 Analyte Wenatchee Richland Umatilla The Dalles Hood River Portland Vancouver St. Helens Longview (2008) (2009) (a.m.) (noon) (p.m.) Personal care products—Continued Indole – Present – Present – Present – – – – – E 0.11 Menthol <0.50 – – <0.25 <0.33 <0.24 <0.29 <0.51 – – 0.32 3.2 3-Methyl-1H-indole (skatol) Present Present – Present Present Present Present Present Present – – Present Phenol – – – Present – – – Present – – – Present Tonalide Present E 0.15 E 0.18 – E 0.11 E 0.12 Present E 0.14 E 0.11 Present Present E 0.11 Triclosan 0.56 0.44 – E 0.13 0.24 0.25 0.22 0.29 0.21 E 0.29 0.76 0.64 Triethyl citrate (ethyl citrate) 0.51 0.52 E 0.13 – 0.44 0.23 0.58 0.59 0.43 E 0.26 E 0.13 0.51 Pesticides Atrazine – Present – – – – – – – – – – 3,4-Dichlorophenyl isocyanate E 0.17 – Present Present Present E 0.077 E 0.090 E 0.14 Present – E 0.12 – Metalaxyl – – – E 0.14 – – – – – – – – N,N-diethyl-meta-toluamide (Deet) E 0.15 Present – – Present – 0.32 0.31 0.24 – E 0.15 0.3 Plasticizers Bisphenol A Present Present – – ND – – – ND Present Present 0.58 Diethyl phthalate (DEP) – Present – – – – – 0.23 – – Present E 0.19 bis-(2-Ethylhexyl) phthalate (DEHP) – Present E 1.2 E 1.7 – – – E 1.3 – – Present Present Triphenyl phosphate Present E 0.10 Present – Present Present Present Present Present Present Present Present Polycyclic aromatic hydrocarbons (PAHs) Anthracene – – – – – – – – – – Present – 2,6-Dimethylnaphthalene – – – – – – – – – – – Present Fluoranthene E 0.11 – – – – – – – – – – – 1-Methylnaphthalene – – – – – – – – – – – E 0.044 2-Methylnaphthalene – – – – – – – – – – – E 0.047 Naphthalene – – – – – – – – – – – E 0.073 Phenanthrene – – – – – – – – – – Present – Pyrene – – Present – Present – Present Present Present – – – Steroids Cholesterol E 6.3 Present E 4.5 Present E 3.1 Present E 4.1 E 3.8 E 3.4 Present E 3.6 E 3.4 3-beta-Coprostanol E 5.8 Present Present Present Present Present E 4.5 E 4.3 E 3.6 Present Present Present beta-Sitosterol E 3.2 E 1.6 E 2.2 E 1.1 E 0.79 E 0.87 E 1.5 E 1.2 E 1.2 E 0.86 E 2.2 E 1.1 beta-Stigmastanol E 1.1 E 0.55 E 0.29 – – – – – – – E 0.97 Present Table 9. Anthropogenic organic compounds detected in unfiltered wastewater-treatment-plant effluent, Columbia River Basin, Washington and Oregon, 2008–09.— Continued [Station names are shown in table 2. Concentrations reported in micrograms per liter. See table A2 for a listing of anthropogenic organic compounds analyzed and their reporting limits. Present, presence is verified, but concentration is not quantified; sometimes the reporting limit for an individual sample is raised because of matrix interference, these instances of non-detection are shown as less-than (<) the raised reporting limit. Abbreviations: ND, not determined because of matrix interferences; E, estimated; –, not detected]
Contaminant Concentrations in Wastewater-Treatment-Plant Effluent 21

Table 10. Pharmaceuticals detected in filtered wastewater-treatment-plant effluent, Columbia River Basin, Washington and Oregon, 

2008–09.

[Station names are shown in table 2. Concentrations reported in micrograms per liter. See table A3 for a listing of pharmaceuticals analyzed in filtered-effluent 

samples and their reporting limits. Present, presence is verified, but concentration is not quantified. Abbreviations: E, estimated; –, not detected]

Analyte

Wenatchee 

Richland Umatilla The Dalles Hood 

River 

Portland

Vancouver St. Helens Longview

(2008) (2009) (a.m.) (noon) (p.m.)

Acetaminophen – – – – – – – – – – – E 2.6

Caffeine – – – – – 0.22 E 1.3 0.65 2.2 – E 12 E 30

Carbamazepine 0.1 0.098 0.052 0.12 0.047 0.077 E 0.030 E 0.023 E 0.028 E 0.037 Present E 0.052

Codeine – – – – – 0.042 0.17 0.19 0.13 – Present –

Cotinine – – – – 0.098 – – – – – 0.071 0.15

Dehydronifedipine – – – Present – – – – – Present – –

Diltiazem E 0.089 Present E 0.047 – E 0.042 E 0.056 – Present Present E 0.043 – –

1,7-Dimethylxanthine – – – – – – – – – – E 0.40 E 5.1

Diphenhydramine 0.090 0.059 E 0.025 Present 0.11 0.082 0.075 0.064 0.056 0.10 E 0.033 E 0.031

Sulfamethoxazole – Present Present E 0.12 – – – – – Present – Present

Thiabendazole 0.22 0.57 – – – – – – – – – –

Trimethoprim 0.15 0.19 0.10 – 0.11 0.12 0.089 0.079 0.076 0.073 E 0.020 0.072

Pharmaceuticals

Pharmaceuticals are expected to be in WWTP effluent 

because of the amount that passes through the body. In 

filtered effluent samples, 14 human-health pharmaceuticals 

were analyzed for and all but albuterol and warfarin 

were detected from at least one city (table 10). Two 

pharmaceuticals were detected in samples collected at all 

WWTPs—carbamazepine, a prescription drug used to treat 

epilepsy, bipolar disorder, and attention deficit hyperactivity 

disorder; and diphenhydramine, a common ingredient in 

over-the-counter medicines used for allergy relief or as a 

sleep aid, although trimethoprim, a prescription antibiotic, 

was detected at all WWTPs except Umatilla. 

A few studies have determined that the 

wastewater-treatment process removes or degrades less 

than 20 percent of the carbamazepine entering the plant 

(Heberer, 2002; Rounds and others, 2009). Therefore, it is 

not surprising that carbamazepine was the most frequently 

detected pharmaceutical in this study, the Chesapeake 

Bay (Pait and others, 2006), Las Vegas Wash (Boyd 

and Furlong, 2002), and streams in Germany (Ternes, 

1998). Little work has been done to assess toxicity of 

carbamazepine in the aquatic environment, but one study 

showed that acute toxicity for bacteria, algae, diatoms, and 

crustaceans was at the milligrams per liter level (Ferrari and 

others, 2004), much higher than the concentrations reported 

here. 

Diphenhydramine and trimethoprim have been reported 

in the Columbia River Basin in trace amounts in both the 

water column and bed sediments (Morace, 2006; Nilsen and 

others, 2007). It is difficult to determine potential aquatic 

effects of diphenhydramine because of its multiple modes of 

action on histamines, acetylcholine, and transporter receptors 

(Berninger and others, 2011). When tested on the aquatic 

invertebrate Daphnia magma, Berninger and others (2011) 

found a no-observed-effect level at the environmentally 

relevant concentration of 0.8 μg/L, eight times higher than 

the highest concentration measured in this study. The highest 

detection frequency of any antibiotics was for trimethoprim 

in a study of streams in the United States (Kolpin and others, 

2002), and was detected in approximately 90 percent of 

WWTP-effluent samples and 20 percent of stream samples 

in a German study (Hirsch and others, 1999). Lindberg and 

others (2007) determined that a trimethoprim concentration of 

16 mg/L in water caused growth inhibition in 50 percent of a 

test species of green algae. Lam and others (2004) calculated 

trimethoprim to have a half-life of 5.7 days. 
22 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Table 11. Estrogenicity in wastewater-treatment-plant effluent samples, instantaneous loadings, and calculated concentrations in the 

Columbia River, Columbia River Basin, Washington and Oregon, December 2008.

[Station names are shown in table 2. Slight, estrogenic response was observed above the 99 percent confidence limits, but below a measurable threshold. A 7Q10 

flow is not available for Umatilla, so 78,000 ft3/s is used for these calculations. Abbreviations: EEQ, estimated estradiol equivalents; ng E2/L, nanograms of 

17β-estradiol per liter; ng E2/g, nanograms of 17β-estradiol per gram; Mgal/d, million gallons per day; 7Q10, the lowest streamflow for 7 consecutive days that 

occurs on average every 10 years; ft3/s, cubic foot per second; g/d, gram per day; –, not detected]

Analyte Wenatchee Richland Umatilla The Dalles Hood River

Portland

Vancouver

(a.m.) (noon) (p.m.)

EEQ in filtered water (ng E2/L) 550 760 91 230 55 1,200 1,800 1,400 780

EEQ in solids filtered from water (ng E2/g) Slight – – – – Slight Slight Slight –

Daily plant discharge for sampling date (Mgal/d) 3.1 5.44 0.545 1.7 0.893 49 49 49 10

Columbia River 7Q10 flow (ft3

/s) 51,557 52,700 78,000 80,637 74,000 79,436 79,436 79,436 79,436

Instantaneous load (g/d) 6.5 16 0.19 1.5 0.19 223 334 260 30

EEQ in Columbia River (ng E2/L) 0.051 0.12 0.0010 0.0075 0.0010 1.1 1.7 1.3 0.15

Estrogenicity

Samples collected from WWTPs in 2008 were screened for 

total estrogenicity of the compounds in the sample using YES (David 

Alvarez, U.S. Geological Survey, written commun., November 6, 

2009). EEQ values are intended to measure the potential biological 

effects of the mixture of chemicals present in the sample, and 

therefore, are not compared to individual compounds in this report.

The compounds that make up these complex mixtures 

likely have not all been measured in this study. 

Likewise, the interactions of these compounds in 

terms of synergistic or antagonistic effects are not 

defined well enough to analyze relationships between 

the EEQ and a list of compounds. A large suite of 

natural and synthetic hormones and phytoestrogens 

that may be available in the environment could 

affect the EEQ. Manmade chemicals like phthalates, 

alkylphenol surfactants, and potentially musks or 

fragrances also may have estrogenicity that could 

contribute to the EEQ measure. For all of these 

reasons, the EEQs measured for this study are not 

related to compound concentrations, but are used 

to indicate a measure of the potential for biological 

effects in the ecosystem. 

For this study, the unfiltered WWTP-effluent 

samples sent to CERC were filtered and the YES 

was performed on both the filtered effluents and the 

solids filtered from these samples (table 11). The 

EEQs measured in the filtered effluents fall into 

groupings related to each WWTP’s discharge rate, 

with higher EEQs (table 11) associated with plants 

with higher flow (table 12). Most of the solid samples 

did not show quantitative levels of estrogenicity. 

This indicates that the hormonally active compounds 

are likely dissolved in the effluent water (David 

Alvarez, U.S. Geological Survey, written commun., 

November 6, 2009). 

Sampling effluent at the Vancouver Westside Wastewater-Treatment Plant, Washington, 

December 2008.
Contaminant Concentrations in Wastewater-Treatment-Plant Effluent 23

Table 12. Physical properties and suspended-sediment results for wastewater-treatment-plant effluent, 

Columbia River Basin, Washington and Oregon, 2008–09.

[Station names are shown in table 2. Abbreviations: Mgal/d, million gallons per day; mg/L, milligrams per liter; μm, micrometer; 

NA, not analyzed]

City Date Time

Daily plant 

discharge for 

sampling date

(Mgal/d)

Water

temperature

(degrees

Celsius)

pH 

(standard 

units)

Suspended 

sediment

(mg/L)

Suspended 

sediment 

(percent finer 

than 63 μm)

Wenatchee 12-02-08 1010 3.1 15.6 6.9 4 98

12-01-09 0850 2.9 18.0 7.4 3 92

Richland 12-04-08 0900 5.4 18.3 7.2 5 64

12-02-09 0820 5.8 NA NA NA NA

Umatilla 12-03-08 0840 0.54 16.9 7.4 2 93

12-02-09 0950 0.53 NA NA NA NA

The Dalles 12-05-08 0830 1.7 15.8 7.0 2 96

12-02-09 1200 1.5 NA NA NA NA

Hood River 12-10-08 0950 0.89 14.0 6.9 4 95

12-02-09 1310 0.92 NA NA NA NA

Portland (a.m.) 12-09-08 0900 49 15.6 8.8 3 95

 (noon) 12-09-08 1150 49 NA NA 5 99

 (p.m.) 12-09-08 1500 49 NA NA 4 94

Portland 12-10-09 0840 58 NA NA NA NA

Vancouver 12-08-08 0940 10 18.5 7.4 3 97

12-02-09 1510 9.7 NA NA NA NA

St Helens 12-03-09 0900 6.9 NA NA 7 96

Longview 12-08-09 0810 6.9 NA NA 6 94

The estrogenicity levels measured in this study are 

well above levels that have been shown to cause effects in 

aquatic biota. In Swiss midland rivers, brown trout showed a 

relationship between sites with higher EEQ values and male 

fish with elevated vitellogenin levels (Vermeirssen and others, 

2005). Colman and others (2009) showed that short-term 

exposure to estrogenic compounds could alter reproductive 

success in male zebrafish. In their experiment, one-half of the 

dominant male zebrafish in waters with EEQ levels of 50 ng/L 

relinquished their paternal dominance. Kidd and others 

(2007) designed a study in which Canadian experimental 

lakes were dosed with varying levels of the synthetic estrogen 

17α-ethynylestradiol to study the long-term effects on fathead 

minnows. Chronic exposure to low concentrations (5–6 ng/L) 

led to the feminization of the males through the production of 

vitellogenin, and ultimately, the near extinction of this species 

from the lake.

In this study, the estrogenicity was measured in the 

effluent itself and not the receiving waters where aquatic biota 

reside. To compare these results to the studies previously 

discussed, instantaneous estrogenicity loadings were 

calculated by multiplying the estrogenicity by the daily plant 

discharge for the WWTP (table 12) and a conversion factor. 

To determine the resulting increase in estrogenicity in the 

Columbia River that could be attributed to this incoming load 

(table 11), the instantaneous load was divided by the 7Q10 

streamflow of the Columbia River at that point of discharge 

(table 2) and multiplied by a conversion factor. The 7Q10 

streamflow is a measure used in National Pollutant Discharge 

Elimination System (NPDES) permit writing that is equal to 

the lowest streamflow for 7 consecutive days that would be 

expected to occur once in 10 years. The 7Q10 streamflow is 

used to determine mixing zones by providing a measure of 

the streamflow available to dilute any inputs at that point in 

the river. The resulting estrogenicity in the Columbia River 

near the Portland WWTP was calculated to be greater than 

1 ng/L (table 11), a concentration that may potentially cause 

endocrine disruption in different aquatic species (Nelson and 

others, 2007). 
24 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Halogenated Compounds

Halogenated compounds were analyzed (table 13) from 

the solids collected by filtering roughly 10–20 L of effluent 

from each WWTP. Concentrations of PBDEs were detected 

at every WWTP, and the highest concentrations detected 

were for congeners PBDE-47, PBDE-99, and PBDE-100. 

Most of these values are reported in table 13 as “Present” 

because of detectable concentrations in the set blanks. The 

few concentrations reported are much higher than those 

for any of the other congeners, which is a typical pattern 

observed in environmental data (Yoqui and Sericano, 2009) 

because these congeners are the most stable. All of the PBDE 

congeners detected in this study also have been detected in 

Osprey eggs collected in Oregon and Washington (Henny and 

others, 2009).

The highest PBDE concentrations were in Richland 

and Portland. The Portland PBDE values showed the lowest 

concentrations occurring in the morning and then the 

concentrations detected later in the day amounting to roughly 

two to four times the morning concentrations. This pattern of 

lower concentrations in the morning and higher concentrations 

later in the day also was observed in the other halogenated 

compounds measured. Interestingly, the suspended-sediment 

concentrations remained fairly low and constant throughout 

the day. Therefore, this pattern of higher concentrations later 

in the day is not due to changes in the amount of suspended 

sediment, but rather the amount of associated with these 

solids. The only WWTP where PCBs were detected was 

in Wenatchee. The reason for this is not known, but, since 

June 2007, there have been fish advisories for mountain 

whitefish in the lower Wenatchee River based on their elevated 

PCB concentrations (Washington State Department of Health, 

2007). Several pesticide compounds were detected in these 

solids. These types of pesticides are more hydrophobic, so 

these compounds likely would be detected in these samples 

and in biosolids, which were not analyzed in this study. 

Currently Used Pesticides

Few currently used pesticides were detected in 

WWTP‐effluent samples (table 14). The primary compounds 

detected were fipronil and its degradates, which were detected 

in all WWTPs except Wenatchee. Fipronil is an insecticide 

used to control common household pests like ants, beetles, 

cockroaches, and other insects, and can be included in topical 

pet-care products used to control fleas (National Pesticide 

Information Center, 2009). A common herbicide degradate, 

3,4-dichloroaniline, was detected at all WWTPs, although 

propiconazole, the only fungicide detected in this study (only 

at St. Helens), but at concentrations approaching 10 μg/L (sum 

of cis- and trans-propiconazole). Propiconazole is a wood 

preservative designed to prevent fungal decay in above ground 

applications (U.S. Environmental Protection Agency, 2008), 

and the St. Helens WWTP gets a large amount of wastewater 

from the nearby Boise Cascade pulp and paper mill.

Mercury

Because of SB 737, mercury and methylmercury 

were added to the analyte list for WWTP-effluent samples 

collected in November 2009 (table 15). The highest total 

mercury concentrations were measured at The Dalles and 

Vancouver. Both concentrations were greater than 12 ng/L, 

the chronic criterion for freshwater aquatic life (Washington 

State Department of Ecology, 2003; Oregon Department of 

Environmental Quality, 2010b). This chronic criterion is the 

average 4-day concentration, whereas the acute criterion 

(1-hour average concentration) of 2,400 ng/L was not 

exceeded in this study. Methylmercury, the bioavailable form 

of mercury in the environment, concentrations were all fairly 

low (0.40 ng/L or less); the highest concentration was detected 

at The Dalles.

Synopsis

Of the 210 compounds analyzed in the WWTP-effluent 

samples, 112 or 53 percent were detected in at least 1 sample 

(fig. 3). Most compound classes had a greater than 80-percent 

detection rate, emphasizing the complex mixtures of 

contaminants present in WWTP effluent. Interesting patterns 

emerge when these percentages of detection are displayed by 

individual WWTP (table 16). Although there are variations 

in the individual composition of the samples for each plant, 

there are many similarities in the frequency of detections 

across the plants. For example, the detection frequency for 

flame retardants at all plants was 65–82 percent. Similarly, 

personal care products, pesticides, steroids, pharmaceuticals, 

and miscellaneous compounds showed similar detection 

frequencies amongst the plants. These similarities illustrate 

that although there are differences between the plants based 

on location, population, treatment type, and plant size, many 

of the results are similar. Of notable difference were the 

PAHs, which were more sporadic, and the PCBs, which were 

detected only at Wenatchee, St. Helens, and Longview. 
Contaminant Concentrations in Wastewater-Treatment-Plant Effluent 25

Table 13. Halogenated compounds detected in solids filtered from wastewater-treatment-plant effluent, Columbia River Basin, 

Washington and Oregon, 2008–09.

[Station names are shown in table 2. Concentrations reported in nanograms per liter. See table A1 for a listing of halogenated compounds analyzed and their 

reporting limits. Present, presence is verified, but concentration is not quantified; sometimes the reporting limit for an individual sample is raised because of 

matrix interference, these instances of non-detection are shown as less than (<) the raised reporting limit. Abbreviations: L, liter; –, not detected; ND, not 

determined because of poor compound recoveries]

Analyte Wenatchee Richland Umatilla The 

Dalles

Hood 

River 

Portland

Vancouver St. 

Helens Longview (a.m.) (noon) (p.m.)

Volume filtered (L) 21 19 18 18 19 20 10 9 18 12 20

Polybrominated diphenyl ethers (PBDEs) or brominated flame retardants

Dechlorane plus Present Present – – – – – – – Present –

Firemaster 680 0.02 0.07 0.02 0.04 0.13 0.05 0.03 0.08 0.06 0.05 –

PBDE-47 Present Present Present Present Present Present Present Present Present Present Present

PBDE-66 0.07 0.22 0.14 0.15 0.09 0.10 0.02 0.11 0.45 0.04 0.05

PBDE-85 0.07 0.28 0.09 0.09 0.08 0.17 0.09 0.21 0.21 0.08 0.12

PBDE-99 Present Present Present Present Present Present Present 4.8 Present Present Present

PBDE-100 Present 1.6 Present Present Present Present Present Present Present Present Present

PBDE-138 0.02 0.06 0.04 0.03 0.03 0.05 0.02 0.08 0.06 0.03 –

PBDE-153 0.12 0.40 0.25 0.14 0.15 0.06 0.11 0.36 0.27 0.16 0.16

PBDE-154 0.12 0.38 0.27 0.15 0.15 0.25 0.08 0.31 0.28 0.15 0.16

PBDE-183 – 0.05 0.03 0.03 0.04 0.04 0.02 0.04 0.04 – –

Polychlorinated biphenyls (PCBs)

PCB-101 – – – – – – – – – – Present

PCB-146 0.01 – – – – – – – – – –

PCB-170 0.01 – – – – – – – – – –

PCB-174 0.01 – – – – – – – – – –

PCB-177 0.01 – – – – – – – – – –

PCB-180 0.02 – – – – – – – – 0.02 0.01

PCB-183 Present – – – – – – – – – –

PCB-187 0.01 – – – – – – – – – –

PCB-194 Present – – – – – – – – – –

Herbicides and insecticides

cis-Chlordane 0.03 0.19 0.02 0.08 0.05 0.10 – 0.05 0.05 0.07 0.09

trans-Chlordane 0.02 0.19 0.01 0.05 0.03 0.08 0.02 0.06 0.03 0.01 0.05

Chlorpyrifos – – – – – 0.18 0.18 0.43 – 0.04 0.03

Cyfluthrin – 0.26 – 0.18 – 0.26 0.07 0.41 – – –

lambda-Cyhalothrin 0.02 Present – – – Present – Present – – –

Desulfinylfipronil – Present Present 0.02 0.02 Present – Present 0.07 – –

Dieldrin 0.01 0.17 – – 0.05 0.14 – 0.09 0.08 – < 0.04

alpha-Endosulfan 0.01 – – – – – – – – – –

Fipronil ND 0.22 0.06 0.17 0.20 0.99 0.35 0.77 1.4 ND 0.05

Fipronil Sulfide – 0.03 0.02 Present 0.02 0.06 0.02 0.06 0.08 0.04 0.01

cis-Nonachlor Present – – – – – – – – – 0.01

trans-Nonachlor 0.01 0.10 Present 0.03 – 0.04 – 0.04 – 0.01 0.03

Pentachloroanisole Present Present – – Present – – – 0.85 – Present

Trifluralin Present – – – – 0.02 – 0.02 – – –

Other compounds

Hexachlorobenzene 

(HCB)

– – Present – – – – – – – –

Methoxy triclosan 1.2 3.7 – – 4.6 1.7 – – 13 Present 1.1

Triclosan Present Present – Present Present 55 Present 57 86 – ND
26 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Table 14. Currently used pesticides and degradates detected in filtered wastewater-treatment-plant effluent, Columbia River 

Basin, Washington and Oregon, December 2009.

[Station names are shown in table 2. Concentrations reported in micrograms per liter. See table A4 for a listing of pesticides analyzed and their reporting 

limits. Present, presence is verified, but concentration is not quantified; sometimes the reporting limit for an individual sample is raised because of 

matrix interference, these instances of non-detection are shown as less than (<) the raised reporting limit. Abbreviations: E, estimated; –, not detected]

Analyte Wenachee Richland Umatilla The 

Dalles

Hood 

River Portland Vancouver St. Helens Longview

Fungicides

cis-Propiconazole – – – – – – – E 2.8 –

trans-Propiconazole – – – – – – – E 6.9 –

Herbicides and degradates

Atrazine – Present – – – <0.0095 Present – –

3,4-Dichloroaniline1 E 0.034 E 0.056 E 0.052 E 0.12 E 0.021 <0.065 E 0.28 E 0.034 E 0.13

Metolachlor – – – – – – – E 0.012 –

Prometon – Present Present – – – – – –

Simazine – – – E 0.005 – – – – –

Insecticides and degradates

Carbaryl – – – E 0.092 – – – – Present

Desulfinylfipronil1 – Present Present Present Present – Present Present Present

Fipronil – E 0.027 Present E 0.042 E 0.056 E 0.078 E 0.087 <0.047 E 0.13

Fipronil sulfide1 – Present Present Present Present Present Present 0.022 E 0.006

Fipronil sulfone1 – Present – – Present – Present – 0.024

Other compounds

1-Naphthol1 – – – Present – – – – Present

1

Degradate.

Ducks swimming in the clarifier at the City of Wenatchee Wastewater-Treatment Plant, 

Washington, December 2009.
Contaminant Concentrations in Wastewater-Treatment-Plant Effluent 27

Table 15. Mercury species in unfiltered wastewater-treatmentplant effluent and stormwater runoff, Columbia River Basin, 

Washington and Oregon, 2009–10.

[Station names are shown in tables 2 and 3. Outfalls sampled prior to 

December 2009 were not analyzed for mercury species. Concentrations are 

reported in nanograms per liter (ng/L). Symbol: –, not detected at a reporting 

limit of 0.04 ng/L]

City or 

short name Date Time Methylmercury

Total 

mercury

Wastewater-treatment-plant effluent

Wenatchee 12-01-09 0850 – 4.1

Richland 12-02-09 0820 0.19 4.2

Umatilla 12-02-09 0950 – 1.9

The Dalles 12-02-09 1200 0.40 16

Hood River 12-02-09 1310 – 2.7

Portland 12-10-09 0840 0.14 7.6

Vancouver 12-02-09 1510 0.06 13

St Helens 12-03-09 0900 0.15 3.9

Longview 12-08-09 0810 0.22 10

Stormwater runoff

Wenatchee 12-21-09 1340 0.09 3.4

Vancouver1 12-16-09 1340 – 8.8

Vancouver2 12-16-09 1210 0.07 15

Willamette1 06-04-10 0840 – 6.3

Willamette2–Dec 12-15-09 1330 0.39 230

Willamette2–May 05-26-10 1410 – 74

Willamette3 12-15-09 1310 – 17

Willamette4 05-26-10 1310 0.11 12

St. Helens 03-30-10 1310 0.07 3.1

Longview 03-30-10 1410 – 2.1

Detergent metabolites

Flame retardants

Miscellaneous

Personal care products

Pesticides

Plasticizers

PAHs

Steroids

Pharmaceuticals

PCBs

Overall

0 10 20 30 40 50 60 70 80 90 100

Compounds detected, percent

Number of compounds detected of

total number analyzed

7/8

15/17

14/17

12/15

27/104

4/4

8/9

4/4

12/14

9/18

112/210

Figure 3. Percentage of compounds 

detected in wastewater-treatment-plant 

effluent, Columbia River Basin, Washington 

and Oregon, 2008–09.
28 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Table 16. Percentage of compounds detected in each wastewater-treatment plant sampled, Columbia River Basin, Washington and 

Oregon, 2008–09.

[Station names are shown in table 2] 

Compound

class

Total 

number 

analyzed

Wenatchee Richland Umatilla The 

Dalles

Hood 

River 

Portland

Vancouver St. 

Helens Longview

(a.m.) (noon) (p.m.)

Detergent metabolites 8 50 38 0 50 50 63 63 63 38 63 63

Flame retardants 17 82 76 76 82 82 82 82 82 82 82 65

Miscellaneous 17 47 24 29 35 24 35 35 47 24 35 53

Personal care products 15 60 33 47 47 53 47 53 47 40 53 80

Pesticides 104 12 12 18 15 13 9 13 9 16 13 15

Plasticizers 4 100 50 25 50 25 25 75 50 50 100 100

Polycyclic aromatic 

hydrocarbons (PAHs)

9 0 11 0 11 0 11 11 11 0 22 44

Steroids 4 100 100 75 75 75 75 75 75 75 100 100

Pharmaceuticals 14 43 29 36 36 43 43 36 43 43 50 57

Polychlorinated biphenyls 

(PCBs)

18 44 0 0 0 0 0 0 0 0 6 11

Overall 210 37 25 28 33 29 29 32 30 30 33 40

Access point for sampling effluent at Vancouver Westside Wastewater-Treatment Plant, 

Washington, December 2008.
Contaminant Concentrations in Stormwater Runoff 29

Contaminant Concentrations in 

Stormwater Runoff 

Halogenated Compounds

When compared to the WWTP samples, the 

stormwater samples analyzed for halogenated 

compounds had many more performance or matrix 

issues, resulting in many raised detection limits 

(table 17). As a result, the patterns observed were 

quite different from those in the WWTP-effluent 

samples; these differences may reflect differences 

between the stormwater runoff and the WWTPeffluent samples. Because of this reporting 

variability, it is difficult to do a complete analysis 

of these results. For all classes of compounds in 

this analysis, however, a few samples stood out. A 

suspended-sediment sample with a concentration 

of 834 mg/L was collected during the first rain of 

autumn 2009 from Umatilla, indicating that a large 

amount of material was available for compounds to 

attach (table 18). The median suspended‐sediment 

concentration for all stormwater-runoff samples was 

21 mg/L. 

The elevated suspended-sediment concentration 

of 47 mg/L measured in the Willamette2-Dec sample 

does not provide a complete explanation as to why 

the highest contaminant concentrations were detected 

in December and May. The sources contributing to 

this drainage area may explain the anomalously high 

concentrations of PBDEs. Of the 51 halogenated 

compounds detected when all the stormwater sites 

are considered, 46 were in the Willamette2-Dec 

sample (table 17). The PBDE concentrations at 

Willamette2 were roughly twice those detected in 

the Umatilla sample and the PCB concentrations at 

Willamette2 were 20–300 times greater than PCB 

concentrations at any other stormwater locations. 

The Willamette 2, 3, and 4 stormwater locations 

are all within the Portland Harbor Superfund area 

(U.S. Environmental Protection Agency, 2010), but 

are not in areas that are currently being studied. 

The Portland Harbor Superfund site is a 10-mile 

stretch of historical industrial usage in the lower 

Willamette River where heavy metals, PCBs, PAHs, 

dioxin/furans, and pesticides have been detected. 

Investigation and cleanup have been occurring at 

the site since 1997. Concentrations measured at the 

Willamette2 site indicate that there are still active 

inputs of contaminants in the area. 

Stormwater outfall at Klindt Point in The Dalles, Oregon, February 2009.
30 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 Table 17. Halogenated compounds detected in solids filtered from stormwater runoff, Columbia River Basin, Washington and Oregon, 2009–10. [Station names are shown in table 3. Outfalls shown in downstream order; concentrations reported in nanograms per liter. See table A1 for a listing of halogenated compounds analyzed and their reporting limits. Present, presence is verified, but concentration is not quantified. Abbreviations: L, liter; –, not detected; ND, not determined because of poor compound recoveries; sometimes the reporting limit for an individual sample was raised because of matrix interference, these instances of non-detection are shown as less-than (<) the raised reporting limit] Analyte Wenatchee Richland Umatilla The Dalles Hood River Portland1 Vancouver1 Vancouver2 Portland2 Willamette1 Willamette2 Willamette3 Willamette4 St. Helens Longview –Dec –May Volume filtered (L) 2.7 9.4 3.0 10.2 11.3 3.7 5.1 5.5 3.6 4.7 2.9 2.3 5.4 2.3 3.4 4.3 Polybrominated diphenyl ethers (PBDEs) or brominated flame retardants Dechlorane Plus – – Present Present – Present Present Present Present – 5.2 E 1.6 – < 0.64 – – Firemaster 680 – – 0.36 Present – – – – – – 4.7 0.78 – 0.52 – – Pentabromotoluene – – – – – – – – – – 0.13 – – – – – PBDE-47 < 1.1 ND Present ND ND – < 1.1 < 1.2 < 0.99 < 0.69 18 Present < 0.62 < 1.1 < 1.1 < 0.16 PBDE-66 – ND 0.45 – – – – Present – – 0.43 0.27 – – – – PBDE-85 – – 0.60 ND – – – – 0.11 – 1.1 0.57 – – – – PBDE-99 < 0.39 ND 9.3 ND ND < 0.21 < 0.63 < 0.68 < 0.79 Present 22 12 < 0.30 Present < 0.67 < 0.10 PBDE-100 < 0.10 ND 2.0 ND ND < 0.05 < 0.16 < 0.18 < 0.17 < 0.09 4.2 2.3 < 0.08 < 0.18 Present – PBDE-138 – – 0.14 – – – – –

– – < 0.23 0.19 – – – –

PBDE-153 – – < 0.96 – – – – 0.06 0.11 0.03 2.6 1.1 0.04 0.10 0.08 –

PBDE-154 – – 0.85 – ND – – – 0.12 0.03 1.8 0.96 – – 0.07 –

PBDE-183 – – – – – – – – – – 3.1 0.26 – < 0.16 – –

Polychlorinated biphenyls (PCBs)

PCB-52 – – – – – – – – – – 40 – – – – –

PCB-70 – – – – – – – – – – 32 – – – – –

PCB-101 – – – – – – – – – – 80 – – – – –

PCB-110 – – – – – – – – – – 85 – – – – –

PCB-118 – – – Present – – – Present – – 65 0.54 – 0.50 – –

PCB-138 – – – – – – – – – – 26 0.42 – 0.31 – –

PCB-146 – – – Present – – – – – – 8.5 0.16 – 0.08 0.06 –

PCB-149 – – – – – – – – – – 49 < 1.1 – < 0.49 – –

PCB-151 – – – – – – – – – – 8.9 0.20 – 0.08 – –

PCB-170 – – – Present – – – – 0.05 – 9.7 0.34 0.05 0.15 – –

PCB-174 – – – – – – – – 0.15 – 6.5 0.42 0.05 0.18 – –PCB-177 – – – – – – – – – – 4.0 0.26 – 0.15 – –

PCB-180 0.06 – < 0.06 Present – – 0.06 0.08 0.08 0.06 14 0.77 0.08 0.23 0.07 0.02

PCB-183 – – – – – – – – – – 3.7 0.18 – – – –PCB-187 – – – Present – – – – 0.03 – 5.8 0.37 0.04 0.11 – –

PCB-194 – – – Present – – – – Present – 1.7 Present Present – – –

PCB-206 – – < 0.95 – – – – – – – 0.90 0.12 0.02 0.05 – –
Contaminant Concentrations in Stormwater Runoff 31

Analyte Wenatchee Richland Umatilla The Dalles Hood River Portland1 Vancouver1 Vancouver2 Portland2 Willamette1 Willamette2 Willamette3 Willamette4 St. Helens Longview –Dec –May

Volume filtered (L) 2.7 9.4 3.0 10.2 11.3 3.7 5.1 5.5 3.6 4.7 2.9 2.3 5.4 2.3 3.4 4.3

Herbicides and insecticides

cis-Chlordane – – 1.3 – – – 0.38 – 0.07 0.13 6.1 1.5 – – < 0.76 –

trans-Chlordane – – 0.45 – – – 0.23 – Present 0.04 4.6 0.94 – – Present –

Chlorpyrifos – 0.16 1.5 – Present – 0.93 0.93 0.58 0.31 24 4.0 0.07 0.31 0.12 –

Cyfluthrin – 3.1 < 2.4 – – – < 2.2 – – – 5.9 3.0 – – – –

lambda-Cyhalothrin – – 0.81 – – – – – – – 1.2 0.49 – – – –

Dacthal (DCPA) – 0.56 7.3 – – – – – – 0.03 0.50 0.37 – Present – –

p,p'-DDE – – – – – – – – – – 6.1 – – – – –

p,p'-DDT – – – – – – – – – – – 17 – – – –

Dieldrin – – – – – – 0.29 – – – 3.0 5.7 – – – –

alpha-Endosulfan 0.10 – 3.7 – – – 0.10 0.11 – 0.13 – 0.16 – Present – –

Fipronil ND – ND – – ND ND ND ND – 0.92 1.0 ND – – –

Fipronil sulfide – – – – – – – – – – – 0.03 – – – –

cis-Nonachlor – – 0.38 – – – 0.13 0.02 – – 1.0 0.25 – – – –

trans-Nonachlor – – 0.82 – – – 0.22 0.03 Present 0.03 2.8 0.72 – – – –

Oxyfluorfen – – 3.3 – – – Present Present Present – – Present – – – –Pendimethalin – – < 10 – – – 82 150 < 0.72 1.45 13 – – – – –

Pentachloroanisole – – Present – – – 0.57 Present Present < 0.12 1.2 < 0.35 Present < 0.17 Present < 0.04

Pentachloronitrobenzene – – 4.1 – – – 0.46 0.76 – – 0.54 < 1.2 – – 0.10 –

Trifluralin Present E 0.02 0.58 Present – – 1.6 0.16 < 0.10 0.17 5.5 7.7 0.04 Present 0.07 –

Other compounds

Hexachlorobenzene 

(HCB)

– – Present – – – Present Present – – Present < 0.25 < 0.03 – < 0.18 –

Tetradifon – – – – – – – – – – 0.40 – – – – –

Triclosan – Present ND ND ND ND – – ND ND Present ND – ND < 3.9 –

Table 17. Halogenated compounds detected in solids filtered from stormwater runoff, Columbia River Basin, Washington and Oregon, 2009–10.—Continued[Station names are shown in table 3. Outfalls shown in downstream order; concentrations reported in nanograms per liter. See table A1 for a listing of halogenated compounds analyzed and their reporting limits. Present, presence is verified, but concentration is not quantified. Abbreviations: L, liter; –, not detected; ND, not determined because of poor compound recoveries; sometimes the reporting limit for an individual sample was raised because of matrix interference, these instances of non-detection are shown as less-than (<) the raised reporting limit]
32 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Table 18. Physical properties and suspended-sediment results for stormwater runoff, 

Columbia River Basin, Washington and Oregon, 2009–10.

[Station names are shown in table 3. Abbreviations: L/min, liters per minute; mg/L, milligrams per liter; μm, 

micrometer; μS/cm, microSiemens per centimeter; –, not determinded at time of sampling or not analyzed; E, 

estimated]

Analyte

Estimated 

discharge from 

pipe during 

sampling

(L/min)

Suspended

sediment

(mg/L)

Suspended

sediment

(percent finer

than 63 μm)

pH

(standard

units)

Specific 

conductance 

(μS/cm)

Wenatchee 0.5 5 78 7.2 144

Richland – 9 82 – –

Umatilla – 834 86 – –

The Dalles 1.8 22 99 – –

Hood River 1.7 2 59 – –

Portland1 10 20 95 – –

Vancouver1 12 61 80 7.3 E 12

Vancouver2 0.8 62 94 7.5 E 38

Portland2 12 10 88 7.6 E 36

Willamette1 – 12 93 7.9 140

Willamette2–Dec 3.3 47 97 6.5 131

Willamette2–May 3.3 36 98 6.8 263

Willamette3 – 162 95 7.1 E 98

Willamette4 2.5 42 98 7.4 112

St Helens 40 5 94 7.1 144

Longview 60 53 99 6.9 243

Herbicides and insecticide detection patterns for the 

solids filtered from stormwater runoff also follow a pattern 

of high contaminant concentrations in those samples with 

high suspended-sediment concentrations—particularly 

from Umatilla, Vancouver, and Willamette2. The pesticides 

analyzed on these solids are expected to be associated with 

and therefore, transported, with sediment and solids. Higher 

suspended-sediment concentration does not account for the 

complete pattern observed, however. The second largest 

suspended-sediment concentration measured in this study was 

at the Willamette3 site, but only 3 pesticides were detected in 

this sample compared with the 15 pesticides detected in the 

Willamette2-Dec sample. This indicates that land use in the 

drainage area likely is an important factor when examining 

occurrence and distribution. Examining land-use patterns 

was outside the scope of this report, but toxic-reduction 

efforts will be more effective when contaminant occurrence 

and distribution data is coupled with land-use information 

from the various stormwater catchments that drain to the 

Columbia River. 

The sample collected at the Willamette2 site in May 

included p,p′-DDT, which is somewhat unusual because it is 

not often the parent compound that is detected but rather one 

of the degradates, often p,p’-DDE. The pipe at the Willamette2 

location drains an area that was historically used by a 

pesticide manufacturer. Therefore, remnants of contaminants 

from historical land uses may still be contributing to the 

receiving waters periodically through stormwater runoff. The 

stormwater samples from both Vancouver locations are notable 

for one compound, pendimethalin, a pre-emergent herbicide 

used for control of grassy weeds (Koski, 2008). 

Currently Used Pesticides

No single pesticide was detected at all of the locations 

where filtered-stormwater-runoff samples were analyzed, 

but among those detected, herbicides and insecticides were 

detected most often (table 19). This may have been caused 

by the timing of the samplings; however, no obvious pattern 

of detections was noted between the autumn/winter and 

spring storms. The highest numbers of detections were in 

the Portland/Willamette area, with the most detections and 

highest concentrations at the Willamette2 site. Detections 

for several pesticides and PCBs from the Willamette2 site 

in December and May exceeded chronic freshwater-quality 

criteria (table 20). Although many of these concentrations are 

low (less than 1 μg/L), mixtures of some of these pesticides 

have synergistic and additive effects on salmon health when 

they occur together (Scholz and others, 2006; Laetz and 

others, 2009). 
Contaminant Concentrations in Stormwater Runoff 33

Table 19. Currently used pesticides and degradates detected in filtered stormwater runoff, Columbia River Basin, Washington and Oregon, 2009–10.[Station names are shown in table 3. Concentrations reported in micrograms per liter. See table A4 for a listing of pesticides analyzed and their reporting limits. Present, presence is verified, but concentration is not 

quantified. Abbreviations: E, estimated; –, not detected; sometimes the reporting limit for an individual sample was raised because of matrix interference, these instances of non-detection are shown as less than (<) the raised reporting limit]

Analyte Wenatchee Richland Umatilla The Dalles Hood River Portland1 Vancouver1 Vancouver2 Portland2 Willamette1 Willamette2 Willamette3 Willamette4 St. Helens Longview –Dec –May

Fungicides

Metalaxyl – – <0.013 – – <0.042 <0.014 <0.021 – <0.0149 <0.020 – E 0.017 – – –

Myclobutanil 0.097 – – – – – – – <0.040 – – – – – – –

cis-Propiconazole E 0.059 – – – – – <0.019 <0.023 – E 0.024 <0.056 E 0.055 <0.024 E 0.015 – E 0.030

trans-Propiconazole E 0.069 – – E 0.016 – – <0.022 – – E 0.038 <0.053 E 0.069 – E 0.018 – E 0.043

Tebuconazole 0.076 – – – – – – – – <0.0362 <0.064 0.081 – – – –

Herbicides and degradates

Atrazine – 0.022 – – – 0.038 <0.009 <0.008 – 0.011 <0.016 0.032 <0.008 – – –

4-Chloro-2-methylphenol1 – <0.007 <0.004 – – – – – – – E 0.322 E 1.1 E 0.008 – – –

DCPA (Dacthal) Present 0.032 0.027 Present Present Present – – – Present – Present – Present – –

3,4-Dichloroaniline1 – – E 0.010 E 0.073 – <0.008 – – – – – – – – – –

EPTC – 0.029 E 0.005 – – – – <0.003 – – – – – – – –

Hexazinone – – – – – – – – – – – – – – – 0.021

Metolachlor – 0.026 E 0.013 – – E 0.024 – – 0.021 E 0.011 – – – E 0.009 – –

Pendimethalin – – 0.027 – – E 0.028 0.10 0.16 0.032 0.032 <0.043 – – – – –

Simazine <0.035 – – 0.10 – 0.063 <0.008 0.14 – 0.051 0.058 0.046 <0.008 0.036 – 0.025

Tebuthiuron – – – 0.22 – <0.042 – – – – 0.17 0.62 0.056 0.12 0.054 0.11

Trifluralin – – – – – – Present – – Present E 0.012 E 0.013 – – – –

Insecticides and degradates

Carbaryl E 0.13 E 0.20 Present – – E 0.038 Present – – – E 0.37 E 0.38 – Present – Present

Chlorpyrifos – – <0.018 – – E 0.062 – <0.016 <0.016 – E 0.017 – – – – –Desulfinylfipronil1 – – – – E 0.007 Present Present Present – Present Present – – – – –

Diazinon 0.13 <0.010 <0.018 – – <0.024 <0.005 – – < 0.007 0.072 0.78 – – – –

Fipronil – – Present – Present – Present – – – E 0.014 E 0.049 – – – –

Malathion – – – – – – – – – – 0.50 1.3 – – – –

Other compounds

Ethoprop – – <0.083 – – 2.9 – – <0.019 < 0.020 – – – – – –1-Naphthol1 – E 0.026 Present – – – Present E 0.016 Present – E 0.030 E 0.056 – – – –

1 Degradate. 
34 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Table 20. Concentrations exceeding freshwater-quality criteria for pesticides and polychlorinated biphenyls (PCBs) in stormwater 

runoff from the Willamette2 site, Columbia River Basin, Washington and Oregon, December 2009 and May 2010.

[Concentrations are in micrograms per liter. Acute: Criteria refer to an instantaneous concentration not to be exceeded at any time. Chronic: Criteria refer to a 

24-hour average concentration not to be exceeded. References for criteria are: U.S. Environmental Protection Agency (EPA), 2009b; Oregon (OR) Department 

of Environmental Quality, 2010b; Washington (WA) State Department of Ecology, 2003. Abbreviations: CMC, criterion maximum concentration; CCC, 

criterion continuous concentration; –, no acute criteria]

Analyte Agency standard Acute

(CMC)

Chronic

(CCC)

Concentration range 

detected in this study

Crtierion 

exceeded December May

Chlordane EPA, OR, WA 2.4 0.004 0.00007–0.011 Chronic X

DDT (and metabolites) EPA, OR, WA 1.1 0.001 0.0061–0.017 Chronic X X

Diazinon EPA – 0.17 0.072–0.78 Chronic X

Dieldrin WA 2.5 0.002 0.00029–0.0057 Chronic X X

Malathion EPA, OR – 0.1 0.5–1.3 Chronic X X

PCBs EPA, OR, WA 2 0.014 0.00002–0.44 Chronic X

Stormwater drain, Portland, Oregon, October 2009.

Stormwater outfall under west end of St. John’s railroad bridge 

(Willamette2), Portland, Oregon, October 2009. 
Contaminant Concentrations in Stormwater Runoff 35

Polycyclic Aromatic Hydrocarbons

Most concentrations of PAHs in stormwater runoff were 

low (less than the MDL), and the numbers of detections 

were consistent among locations, except for Hood River 

and St. Helens, where no PAHs were detected (table 21). 

Samples collected in the Portland/Vancouver area had the 

highest number of detections, likely due to the higher density 

of potential sources in the area, including industry and 

automobiles. In contrast, Umatilla is a small town with little 

urban development; however, the stormwater-runoff sample 

from Umatilla had a large number of detections. This is likely 

attributable to the large suspended-sediment concentration 

(834 mg/L, table 18) and the effects of roadway runoff 

adjacent to the site. 

Trace Elements and Mercury

The 10 trace elements measured in filtered and 

unfiltered stormwater runoff in this study were detected 

fairly consistently through all samples (table 22), except 

for mercury, silver, and selenium, which were detected in 

only about one‐half of the unfiltered-water samples. The 

detection limits are lower for filtered-water analyses; thus, 

selenium was detected at low concentrations in most of 

these samples, but mercury and silver were detected only 

in a few samples. The ratio of the concentration of each 

element in the filtered-water sample to that in the unfilteredwater sample indicates that selenium, cadmium, nickel, 

zinc, arsenic, and copper are transported more readily in the 

dissolved phase, whereas chromium, silver, lead, and mercury 

are more often transported in the solid phase (fig. 4). When 

suspended‐sediment concentrations are higher, such as in 

the samples from Umatilla, Willamette3, and Vancouver1 

(table 18), higher concentrations are measured in both phases 

and the ratio shifts. 

Chronic and sometimes acute freshwater-quality criteria 

for cadmium, copper, lead, and zinc were exceeded at several 

stormwater-runoff sites (table 23). These concentrations also 

were high enough to potentially cause health effects in aquatic 

biota. Copper has been shown to cause sublethal effects on 

salmon at concentrations as low as 2 μg/L (Baldwin and 

others, 2003); most concentrations measured in this study were 

greater than 2 μg/L. Chromium and zinc have been determined 

to cause reproductive issues in rainbow trout at levels as low 

as 0.005 and 20 μg/L, respectively (Billard and Roubaud, 

1985). All chromium and most zinc concentrations measured 

in this study (table 22) were higher than these sublethal effects 

levels. Although fish do not live in these stormwater pipes, the 

mixing zones where runoff enters their receiving waters are 

likely inhabited by biota. 

Stormwater runoff entering the Willamette River near the St. John’s railroad bridge, 

Portland, Oregon, October 2009.
36 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 Table 21. Polycyclic aromatic hydrocarbons (PAHs) detected in unfiltered stormwater runoff, Columbia River Basin, Washington and Oregon, 2009–10. [Station names are shown in table 3. Concentrations are in micrograms per liter. See table A5 for a listing of compounds analyzed and their reporting limits. Present, presence is verified, but concentration is not quantified; Abbreviations: E, estimated;–, not detected] Analyte Wenatchee Richland Umatilla The Dalles Hood River Portland1 Vancouver1 Vancouver2 Portland2 Willamette1 Willamette2 Willamette3 Willamette4 St. Helens Longview –Dec –May Acenaphthene – – – – – – – Present Present – Present Present Present Present – Present Acenaphthylene – – – – – – – – – – – – Present – – – Anthracene – – Present – – – – Present Present – Present Present Present Present – Present Benzo[a]anthracene – – Present Present – – – – Present – E0.25 Present

E0.13 – – Present

Benzo[a]pyrene – – Present Present – – Present

E0.17 Present – E0.25 Present

E0.19 Present – E0.17

Benzo[b]fluoranthene – Present

E0.23 Present – – Present

E0.26

E0.24 – 0.39 Present

E0.19 Present – E0.23

Benzo[ghi]perylene – – Present Present – – Present

E0.20 Present Present

E0.23 Present Present Present – Present

Benzo[k]fluoranthene – – Present Present – – – – Present – E0.18 Present Present – – Present2-Chlorophenol – – – – – – – – – – Present Present – – – –

Chrysene – Present

E0.17 Present – – Present

E0.24

E0.24 – 0.36 Present Present Present – Present

Dibenz[a,h]anthracene – – Present – – – – – Present – – – – – – –

1,2-Dichlorobenzene – – – – – – – – – – – Present – – – –

1,4-Dichlorobenzene – – – Present – – – – – – – Present – – – –

2,4-Dichlorophenol – Present Present – – – – – – – 0.80 2.3 – – – –

Diethyl phthalate Present – – – – Present – – – Present 1.5 Present – – – –

Dimethyl phthalate

E0.71 – – – – – – Present Present Present

E0.61 Present Present Present – –

2,4-Dimethylphenol – Present Present – – 0.44 Present – Present 0.44 2.0 0.38

E0.23 Present – –

Di-n-butyl phthalate Present – – – – E0.20 – – – – E1.0 Present – – – –Di-n-octyl phthalate – – Present – – E0.84

E1.8 – Present – – – – – – –

bis(2-Ethylhexyl) 

phthalate

Present – – – – E3.0

E2.3 2.1 Present < 2.2

E2.9 – – – – –

Fluoranthene Present Present

E0.22 E 0.19 – Present E 0.21 0.35

E0.41 Present 0.78 Present

E0.25 Present – 0.21

Fluorene – – Present – – – Present Present Present – – – Present Present – Present

Indeno[1,2,3-cd]pyrene – – Present Present – – Present Present Present – E0.19 – Present – – Present

Isophorone – Present Present – – – E0.15 Present – Present – Present Present Present – –

Naphthalene – – Present – – – Present Present – Present

E0.21 Present Present – – –

2-Nitrophenol – – – – – – – – – Present – – – – – –

4-Nitrophenol < 1.3 – – Present – – Present

E0.33 Present E0.34 – E0.40 – E0.29 – –

N-Nitrosodiphenylamine – – – – – – Present Present Present Present

E0.18 – – Present – –

Pentachlorophenol

E0.49 Present – Present – E0.57 Present Present

E0.86 E0.31

E0.43 E0.50 Present Present – –

Phenanthrene Present – Present – – Present Present

E0.19

E0.19 Present 0.65 Present Present Present – Present

Phenol – Present Present – – 0.37

E0.20

E0.14 Present 0.32 2.1

E0.15 – Present – Present

Pyrene Present Present

E0.18

E0.18 – Present

E0.18 0.36

E0.37 Present 0.63 Present

E0.25 Present – E0.19

1,2,4-Trichlorobenzene – – Present – – – – – – – – – – – – –

2,4,6-Trichlorophenol – – – – – – – – – – – E0.20 – – – –
Contaminant Concentrations in Stormwater Runoff 37

Table 22. Trace elements detected in stormwater runoff, Columbia River Basin, Washington and Oregon, 2009–10.[Station names are shown in table 3. Concentrations are in micrograms per liter. See table A6 for a listing of trace-element compounds analyzed and their reporting limits. Present, presence is verified, but 

concentration is not quantified. Abbreviation: E, estimated; –, not detected]

Analyte Wenatchee Richland Umatilla The Dalles Hood River Portland1 Vancouver1 Vancouver2 Portland2 Willamette1 Willamette2 Willamette3 Willamette4 St. Helens Longview –Dec –May

Unfiltered water

Arsenic 0.87 2.6 2.3 2.1 Present 0.98 0.64 0.49 0.42 1.1 2.5 2.1 1.8 0.97 0.25 1.7Cadmium 0.08 – 0.50 0.57 – 0.13 0.21 0.10 0.11 0.17 0.77 0.65 0.08 0.15 Present E 0.04Chromium 0.71 0.60 9.0 2.1 – 2.5 6.8 2.9 1.3 2.4 4.7 2.8 4.7 33 Present 0.64Copper 9.6 6.3 42 7.6 Present 20 15 7.8 12 16 22 15 9.3 12 2.2 3.1Lead 2.2 0.76 19 1.2 Present 5.8 21 13 3.6 3.2 53 24 5.0 5.7 0.62 1.3Mercury – – 0.09 E 0.01 – – 0.01 E 0.01 E 0.01 – 0.18 0.07 0.02 0.01 – –Nickel 1.1 1.5 22 2.4 0.23 2.2 2.2 1.2 1.2 2.3 4.3 4.0 3.5 3.3 0.63 0.90Selenium – 0.73 0.13 0.20 – Present – – – – 0.33 0.25 E 0.10 – Present –Silver – – 0.13 – – 0.018 0.019 0.018 Present Present 0.25 0.078 0.020 0.023 – –Zinc 87 17 160 27 7.5 50 93 34 73 150 190 150 28 250 11 28

Filtered water

Arsenic 0.69 2.3 0.42 2.0 0.13 0.73 0.26 0.37 0.26 0.43 1.1 1.4 0.31 0.56 0.14 0.80Cadmium 0.08 0.05 0.03 0.6 E 0.02 0.07 0.07 0.07 0.08 0.14 0.25 0.48 Present 0.05 E 0.02 0.02Chromium Present Present Present 1.1 Present 1.0 1.6 2.1 0.50 0.68 0.62 Present Present Present Present PresentCopper 9.2 4.5 5.4 7.6 4.6 11 5 7.4 7.8 8.3 5.2 2.6 3.4 1.8 1.9 E 1.0Lead 0.32 0.19 0.12 0.16 0.11 0.59 0.31 12 0.47 0.18 2.9 2 0.08 0.10 0.08 0.03Mercury – – – – – – – – – – 0.01 – – – – –Nickel 1.3 0.89 1.4 1.5 0.23 1.1 0.71 0.98 0.86 1.6 1.9 3.2 0.98 1.0 0.70 0.50Selenium 0.05 0.61 E0.04 0.20 Present E 0.04 Present – Present 0.05 0.34 0.21 0.06 0.05 Present PresentSilver – – 0.02 – – – – – – E 0.01 0.01 – – – – –Zinc 85 12 17 32 7.7 28 39 7.7 60 100 57 47 E 4.5 87 11 18
38 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

tac11-0618_fig04

EXPLANATION

Median concentration

0.0 

0.2 

0.4 

0.6 

0.8 

1.0 

1.2 

1.4 

Ratio, filtered-unfiltered concentration

8 14 16 16 16 16 15 163 1 Selenium Cadmium Nickel Zinc Arsenic Copper Chromium Silver Lead Mercury

Number of samples

Figure 4. Ratio of filtered to unfiltered concentrations of trace 

elements measured in stormwater runoff, Columbia River Basin, 

Washington and Oregon, 2009–10.

Although mercury was determined as part of 

the trace‐elements analytical suite at NWQL for all 

stormwater samples, aliquots from stormwater samples 

collected after November 2009 also were analyzed 

for mercury and methylmercury in unfiltered water at 

much lower detection limits at the Wisconsin Mercury 

Research Laboratory (table 15). The Willamette2 site 

continued to be a key contributor with the highest, by 

far, concentrations of all the stormwater samples at 

230 ng/L in December and 74 ng/L in May. Although 

these values seem very high, they are less than the 

ODEQ-established screening level of 770 ng/L for total 

mercury in stormwater outfalls in the Portland Harbor 

area (Oregon Department of Environmental Quality and 

U.S. Environmental Protection Agency, 2005). The other 

locations with concentrations greater than or equal to the 

chronic criteria for freshwater aquatic life (12 ng/L) are 

Vancouver2, Willamette3, and Willamette4. The levels 

of methylmercury were all low, except at Willamette2, 

which was similar in concentration to that measured 

from The Dalles WWTP. 

Stormwater outfall near Interstate Highway 205 bridge (Portland1), Portland, Oregon, 

October 2009.
Contaminant Concentrations in Stormwater Runoff 39

Table 23. Concentrations exceeding freshwater-quality criteria for trace elements in stormwater runoff, Columbia River Basin, Washington and Oregon, 2009–10.[Station names are shown in table 3. Concentrations are in micrograms per liter; Acute: Criteria refer to the average concentration for 1 hour. Chronic: Criteria refer to the average concentration for 4 days, 

neither of these criteria should be exceeded more than once every 3 years. All criteria are based on concentrations in filtered water, except for mercury, which is based on concentrations in unfiltered water; a 

hardness of 50 milligrams per liter was used for criteria calculations; there were no exceedances of criteria in stormwater collected in Richland, Hood River, St Helens, or Longview. References for criteria are: U.S. Environmental Protection Agency (EPA), 2009b; Oregon (OR) Department of Environmental Quality, 2010b; Washington (WA) State Department of Ecology, 2003. Abbreviations: CMC, criterion maximum concentration; CCC, criterion continuous concentration. E, estimated]

Analyte Agency standard Acute (CMC) Chronic (CCC) Concentration range detected in this study Criterion exceeded Wenatchee Umatilla The Dalles Portland1 Vancouver1 Vancouver2 Portland2 Willamette1 Willamette2 Willamette3 Willamette4 –Dec –May

Cadmium EPA 1.03 0.15 E 0.01–0.6 Chronic X X

Copper OR, WA 8.86 6.28 E 0.68–11 Acute X X

Chronic X X X X X X

Copper EPA 6.99 4.95 E 0.68–11 Acute X X X X X X

Chronic X X X X X X X X X

Lead OR, WA 30 1.17 0.03–12 Chronic X X X

Lead EPA 39 1.17 0.03–12 Chronic X X X

Mercury WA 2.1 0.012 0.002–0.23 Chronic X X X X X

Mercury OR 2.4 0.012 0.002–0.23 Chronic X X X X X

Zinc OR, WA 64 58 4.5–100 Acute X X X

Chronic X X X X

Zinc EPA 65 66 4.5–100 Acute X X X

Chronic X X X
40 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Table 24. Oil and grease detected in stormwater runoff, Columbia River Basin, 

Washington and Oregon, 2009–10.

[Station names are shown in table 3. Concentrations are in milligrams per liter. 

Abbreviations: –, not detected; E, estimated]

Short name Date Time Reporting

limit

Concentration

in sample

Concentration

in method blank

Wenatchee 12-21-09 1340 5.0 – –

Richland 05-02-09 1200 5.0 E 4.4 E 1.5

Umatilla 10-04-09 0920 5.0 E 4.4 E 2.4

The Dalles 02-23-09 1210 5.0 E 3.5 E 2.1

Hood River 02-23-09 1310 5.0 E 4.1 E 2.1

Portland1 10-14-09 1100 5.0 E 4.8 E 2.3

Vancouver1 12-16-09 1340 5.0 E 2.3 –

Vancouver2 12-16-09 1210 5.0 E 3.3 –

Portland2 10-26-09 1210 5.0 E 3.6 –

Willamette1 06-04-10 0840 4.7 E 4.0 E 3.4

Willamette2–Dec 12-15-09 1330 5.0 5.6 –

Willamette2–May 05-26-10 1310 5.4 6.7 E 3.6

Willamette3 12-15-09 1310 5.0 – –

Willamette4 05-26-10 1410 5.5 4.1 –

St Helens 03-30-10 1310 4.7 E 2.5 E 1.7

Longview 03-30-10 1410 4.7 E 2.5 E 1.7

Flame retardants

PCBs

Pesticides

Miscellaneous

PAHs

Trace elements

Overall

0 10 20 30 40 50 60 70 80 90 100

Compounds detected, percent

12/13

17/18

38/93

3/5

34/56

10/10

114/195

Number of compounds detected of

total number analyzed

Figure 5. Percentage of compounds detected in stormwater runoff, Columbia River 

Basin, Washington and Oregon, 2009–10.

Oil and Grease

Oil and grease concentrations in this 

study were consistent and near or less than 

the reporting limit (table 24). The only 

location where concentrations were greater 

than the reporting limit was Willamette2. 

Analytical difficulties with these analyses 

caused method blanks often to show 

concentrations equal to one-half or more 

of the concentration in the environmental 

sample. 

Synopsis

The overall percentage of compounds 

detected in the stormwater-runoff samples 

(58 percent, or 114 of 195, fig. 5) was 

very similar to the percentage detected 

in WWTP-effluent samples (53 percent, 

or 112 of 120, fig. 3). The difference for 

stormwater is that the compounds detected 

were not similar across locations. Trace 

elements were detected at all sites and at 

levels of concern for the health of aquatic 

biota. All of the other compound classes 

were dominated by a few samples with 

high suspended-sediment concentrations—

Umatilla, Willamette3, and Willamette2. 

The suspended-sediment contribution 

alone could not account for the large 

number and elevated concentrations 

measured at the Willamette2 site. Landuse sources in the drainage area play a key 

role at this site, which is located within 

an EPA Superfund project area. Two of 

the ubiquitous compound classes detected 

in the stormwater runoff, trace elements 

and PAHs, are related to automobiles and 

impervious surfaces, typical findings for 

stormwater runoff in urban areas. 
Contaminant Concentrations in Stormwater Runoff 41

 Urban stormwater outfall, Portland, Oregon, October 2009.

Stormwater outfall with spring flowers in downtown Portland, Oregon, May 2009.
42 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

River at Beaver Army Terminal near Longview. The direct 

environmental effects of trimethoprim are not known, but the 

presence of antibiotics in the aquatic environment could lead 

to microbial resistance (Kümmerer, 2004). 

Galaxolide®, the short name for 

hexahydrohexamethylcyclopentabenzopyran (HHCB), is 

a synthetic fragrance used in cosmetics, cleaning agents, 

detergents, air fresheners, and perfumes (International Flavors 

and Fragrances, Inc., 2007). Galaxolide has been shown to be 

anti-estrogenic (Schreurs and others, 2005) and bioaccumulate 

in the food web (Hu and others, 2011). Galaxolide was 

detected in samples collected at all nine WWTPs (table 9) 

with a median concentration of 1.2 μg/L. During the lower 

Columbia River estuary study, trace levels of galaxolide were 

detected in the Columbia and Willamette Rivers during both 

high- and low-flow sampling events (Lower Columbia River 

Estuary Partnership, 2007).

Implications for Columbia River Basin

This study was designed as a reconnaissance to inform 

researchers, scientists, plant operators, policy-makers, and 

regulators about what compounds are being delivered to the 

Columbia River through two pathways, WWTP effluent and 

stormwater runoff. The target analytes included a broad array 

of compounds, including some of Oregon’s SB 737 priority 

pollutant list as well as emerging contaminants such as 

endocrine disruptors, personal care products, flame retardants, 

and other contaminants for which there is little available data 

for the Columbia River Basin. These data can provide a useful 

framework for directing future work to identify and reduce 

contaminant concentrations in the Columbia River Basin. 

Four Case Studies

Two pharmaceuticals—one over-the-counter and one 

prescription—and two AOCs—one musk and one detergent 

metabolite, both endocrine disruptors—were selected for 

further study. All four of these compounds were consistently 

detected in WWTP effluent (fig. 6) and in the Columbia 

River in previous studies. Diphenhydramine is an over-thecounter antihistamine used to treat the symptoms of hay 

fever, allergies, and the common cold; to prevent and treat 

motion sickness; to treat insomnia; and to control abnormal 

muscle movements in patients with early Parkinson’s 

syndrome (PubMed Health, 2010). Diphenhydramine was 

detected in samples collected at all nine WWTPs (table 10) 

with a median concentration of 0.062 μg/L. During a study 

in the lower Columbia River estuary, a trace-level amount 

of diphenhydramine was detected in filtered water from the 

Columbia River at Point Adams near the mouth of the river 

in April 2005 (Lower Columbia River Estuary Partnership, 

2007). At Point Adams, a large amount of water is available 

for dilution, but diphenhydramine was still detected. Little 

is known about the effects of diphenhydramine on aquatic 

biota, but earthworms living in soils treated with biosolids 

accumulated diphenhydramine (Kinney and others, 2008). 

Trimethoprim is an antibiotic prescribed for urinary 

tract infections and also can be used to treat pneumonia and 

“traveler’s diarrhea” (PubMed Health, 2008). When combined 

with sulfamethoxazole, trimethoprim is often used to treat 

ear infections and chronic bronchitis. Besides its use for 

humans, it also is registered for use in dogs, horses, cattle, and 

swine. The median concentration of trimethoprim measured 

in WWTP effluents in this study was 0.089 μg/L, and it was 

detected in eight of the nine WWTPs sampled (table 10). In 

August 2004, trimethoprim was detected at low levels in the 

Columbia River at Warrendale (just downstream of Bonneville 

Dam), the Willamette River at Portland, and the Columbia 

tac11-0618_fig06

EXPLANATION

Median concentration

Concentration, in micrograms per liter

0

0.4 

0.8 

1.2 

1.6 

0 

6 

12 

18 

24 

0

0.05 

0.10 

0.15 

0.20 

Diphenhydramine

Trimethoprim

Galaxolide

Nonylphenol compounds

Figure 6. Concentrations of diphenhydramine, 

trimethoprim, galaxolide, and nonylphenol compounds 

in wastewater-treatment-plant-effluent samples, 

Columbia River Basin, Oregon, 2008–09. (n = 16 for all 

compounds.)
Implications for Columbia River Basin 43

Nonylphenol compounds are a group of nonionic 

detergent metabolites that are present in cleaners and sealers, 

and are produced in large quantities in the United States 

(table A2). They are known endocrine disruptors and are 

toxic to aquatic life, causing reproductive effects in aquatic 

organisms (U.S. Environmental Protection Agency, 2006). 

Nonylphenol compounds are resistant to natural degradation 

in water and their presence in WWTP effluent is often 

as a breakdown product from surfactants and detergents. 

For this discussion, the results for the five nonylphenol 

variants (para‐nonylphenol, NP1EO, NP2EO, OP1EO, 

OP2EO) analyzed are summed to provide a total measure of 

nonylphenol compounds. These compounds were detected 

at 8 of the 9 WWTPs (table 9) with a median concentration 

in Portland of 22 μg/L and a median for the other 7 plants 

of 3.6 μg/L. From a study of emerging contaminants in the 

surficial bed sediment of the lower Columbia River and its 

tributaries in 2005–06, nonylphenol compounds were detected 

in small tributaries (Fanno Creek), larger tributaries (the 

Tualatin River and Columbia Slough), and the Columbia River 

(upstream of the Willamette River and near the Cowlitz River) 

(Nilsen and others, 2007). Therefore, nonylphenol compounds 

may have been discharged from WWTPs consistently enough 

and at high enough concentrations to be measurable in the 

receiving-water environments. 

The freshwater aquatic-life criteria for nonylphenols are 

28 μg/L for the acute (1-hour average) criterion and 6.6 μg/L 

for the chronic criterion (4-day average) (U.S. Environmental 

Protection Agency, 2006). Therefore, the concentrations 

measured at the Portland WWTP exceed the chronic criterion, 

but they do not represent a 4-day average. The European 

Union has banned nonylphenol and nonylphenol ethoxylates 

because they have been determined to be a hazard to human 

and environmental safety (Sierra Club, 2005).

Loadings to the River

For these four example compounds, instantaneous 

loadings from each WWTP were calculated and then 

extrapolated to represent a daily load to the Columbia River 

(table 25). These loads were determined by multiplying the 

concentration of a given contaminant by the daily discharge 

for the WWTP (table 12) and a conversion factor. This 

calculation provides a measure of the instantaneous load of 

the contaminant entering the river at the point of discharge 

if it is assumed that the measured concentration is a good 

representation of the concentration throughout the day for the 

WWTP effluent. The data necessary to quantify the variability 

for each contaminant throughout the day at a given WWTP 

were not collected for this study, but for exploratory purposes, 

these instantaneous loads can be useful to indicate potentially 

important sources of contaminants to the Columbia River. The 

instantaneous loads for the Portland WWTP were consistently 

higher than for any other wastewater-treatment plant because 

the discharge from the Portland WWTP is higher than for any 

other plant. The discharge from Portland is five times larger 

than the next largest WWTP in Vancouver. Additionally, the 

concentrations measured from the Portland WWTP also tended 

to be higher, particularly for the nonylphenols, indicating that 

this maybe an area to focus future reduction efforts. 

The calculations were taken a step further by dividing the 

instantaneous load by the 7Q10 streamflow of the Columbia 

River at that point of discharge (table 2) and multiplying by a 

conversion factor to determine the resulting concentration in 

the Columbia River that could be attributed to this incoming 

load (table 25). These calculations illustrate that the Columbia 

River carries a large amount of water and is able to “absorb” a 

variety of inputs because of its ability to dilute.

The calculated concentrations were all small, mostly 

less than 1 ng/L, except near the Portland WWTP. These 

concentrations, besides Portland, would not be measurable 

in the Columbia River main stem using standard sampling 

techniques. Although these calculated concentrations are small 

in the context of the whole river, the localized effect of these 

continuous inputs to the mixing zone is understudied and 

underrepresented. The aquatic biota using these areas may be 

exposed to higher concentrations than in other areas. 

Comparison to SB 737 Plan Initiation Levels

As part of Oregon’s SB 737 process to identify persistent 

pollutants and reduce concentrations entering Oregon’s 

waterways (Oregon Department of Environmental Quality, 

2010a), ODEQ was tasked with developing PILs for each of 

these pollutants. These PILs are used to determine if a city 

will be required to develop a reduction plan for each persistent 

pollutant. ODEQ selected these PILs from several existing 

values, including drinking-water maximum-contaminant levels 

for those that are established, peer-reviewed national and 

international government documents, and scientific literature 

that reflect current scientific information. 

The reconnaissance data from this study were compared 

to the SB 737 list and PILs to provide some preliminary 

information. Of the 118 persistent pollutants on the SB 737 

list, 63 were not analyzed as a part of this study, and 13 were 

analyzed only in stormwater-runoff samples (table 26). Senate 

Bill 737 applies only to WWTP effluent and not to stormwater 

runoff. Of the remaining 42 pollutants analyzed in wastewater, 

27 were detected. Only 4 of the 27 were measured at least 

once at a level greater than the assigned PIL (table 27). One of 

these, fluoranthene, was detected only in the sample from the 

Wenatchee WWTP (E 0.11 μg/L), which is in Washington and, 

therefore, not subject to the requirements of Oregon SB 737. 

Another PAH, anthracene, was detected in a sample collected 

at the St. Helens WWTP at greater than the PIL of 0.01 μg/L. 

It was measured at a level less than the LT-MDL (reported as 

“Present”), but the quantified result slightly exceeded the PIL 

of 0.01 μg/L. 
44 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 Table 25. Instantaneous loadings and calculated concentrations for diphenhydramine, trimethoprim, galaxolide, and nonylphenol compounds in the Columbia River, Columbia River Basin, Washington and Oregon, 2008–09. [Station names are shown in table 2. A 7Q10 flow was not available for Umatilla, so 78,000 ft3/s was used for these calculations Abbreviatons: Mgal/d, million gallons per day; 7Q10, the lowest streamflow for 7 consecutive days that occurs on average once every 10 years, this value is the Columbia River flow near the discharge point that is used for calculating mixing zones; ft3/s, cubic foot per second; μg/L, micrograms per liter; g/d, grams per day] Analyte Wenatchee Richland Umatilla The Dalles Hood River Portland Vancouver St. Helens Longview (2008) (2009) (a.m.) (noon) (p.m.) Flow values Daily discharge for sampling date (Mgal/d) 3.1 2.9 5.4 0.54 1.7 0.89 49 49 49 10 6.9 6.9 Columbia River 7Q10 flow (ft3/s) 51,557 51,557 52,700 78,000 80,637 74,000 79,436 79,436 79,436 79,436 88,900 97,400 Diphenhydramine Concentration in sample (μg/L) 0.090 0.059 0.025 Present 0.11 0.082 0.075 0.064 0.056 0.10 0.033 0.031 Instantaneous load (g/d) 1.1 0.6 0.5 – 0.7 0.3 14 10 10 3.8 0.9 1 Calculated concentration in Columbia River (μg/L) 0.00001 0.00001 0.000004 – 0.000004 0.000002 0.0001 0.0001 0.0001 0.00002 0.000004 0.000004 Trimethoprim Concentration in sample (μg/L) 0.15 0.19 0.1 – 0.11 0.12 0.089 0.079 0.076 0.073 0.02 0.072 Instantaneous load (g/d) 1.8 2.1 2.0 – 0.7 0.4 17 15 14 2.8 0.5 1.9 Calculated concentration in Columbia River (μg/L) 0.00001 0.00002 0.00002 – 0.000004 0.000002 0.00008 0.00008 0.00007 0.00001 0.000002 0.000008 Galaxolide Concentration in sample (μg/L) 1.5 2.5 1.5 1.3 1.2 1.1 1 1.2 0.97 1.3 0.38 1.2 Instantaneous load (g/d) 18 27 31 2.7 7.7 3.7 190 220 180 47 10 31 Calculated concentration in Columbia River (μg/L) 0.0001 0.0002 0.0002 0.00001 0.00004 0.00002 0.0010 0.0011 0.0009 0.0002 0.00005 0.0001 Nonylphenol compounds Concentration in sample (μg/L) 3.0 2.1 4.3 – 6.5 3.6 23 22 16 1.5 4.9 3.7 Instantaneous load (g/d) 35 23 8.8 – 40 12 4,200 4,100 2,900 58 130 97 Calculated concentration in Columbia River (μg/L) 0.0003 0.0002 0.00005 – 0.0002 0.00007 0.02 0.02 0.01 0.0003 0.0006 0.0004
Implications for Columbia River Basin 45

CAS No. Chemical name

Plan 

initiation 

level

(μg/L)

Analyzed in WWTP effluent but not detected

50-32-8 Benzo[a]pyrene 0.2

91465-08-6 lambda-Cyhalothrin 0.01

72-54-8 p,p′-DDD 0.1

72-55-9 p,p′-DDE 0.1

50-29-3 p,p′-DDT 0.001

333-41-5 Diazinon 0.2

1031-07-8 Endosulfan sulfate 0.1

88671-89-0 Myclobutanil 200

27304-13-8 Oxychlordane (single isomer ) 0.4

42874-03-3 Oxyfluorfen 1.3

35693-99-3 PCB-52 0.5

31508-00-6 PCB-118 0.5

35065-28-2 PCB-138 0.5

40487-42-1 Pendimethalin 6

82-68-8 Pentachloronitrobenzene 20

Analyzed in stormwater runoff only

7440-38-2 Arsenic compounds (in filtered effluent) 10

56-55-3 Benz[a]anthracene 0.02

205-99-2 Benzo[b]fluoranthene 0.5

191-24-2 Benzo[ghi]perylene 2

207-08-9 Benzo[k]fluoranthene 0.002

7440-43-9 Cadmium compounds (in filtered effluent) 5

218-01-9 Chrysene 2

53-70-3 Dibenz[ah]anthracene 0.0004

193-39-5 Indeno[1,2,3-cd]pyrene 0.5

7439-92-1 Lead compounds (in filtered effluent) 15

29082-74-4 Octachlorostyrene 0.2

7782-49-2 Selenium compounds (in unfiltered effluent) 50

88-06-2 2,4,6-Trichlorophenol 2

Not analyzed in this study

98-07-7 Benzotrichloride (trichloromethylbenzene) 0.03

82657-04-3 Bifenthrin 0.02

56-35-9 bis-(Tributyltin) oxide (TBTO) 0.008

143-50-0 Chlordecone (Kepone) 0.5

541-02-6 Cyclopentasiloxane, decamethyl- (D5) 16

556-67-2 Cyclotetrasiloxane, octamethyl- (D4) 7

434-90-2 Decafluorobiphenyl 18

52918-63-5 Deltamethrin (decamethrin) 0.0004

115-32-2 Dicofol 6

56-53-1 Diethylstilbestrol 87

88-85-7 Dinoseb 7

1746-01-6 Dioxins/furans (as 2,3,7,8-TCDD TEQ) 0.00003

72-20-8 Endrin 2

66230-04-4 Esfenvalerate 0.02

13356-08-6 Fenbutatin-oxide 0.5

76-44-8 Heptachlor 0.4

Table 26. Oregon Senate Bill 737 priority persistent pollutants not detected in wastewater-treatment-plant (WWTP) effluent, Columbia 

River Basin, Washington and Oregon, 2008–09.

[CAS No.: Chemical Abstract Service Registry Number® is a Registered Trademark of the American Chemical Society. CAS recommends the verification of 

the CASRNs through CAS Client ServicesSM. Abbreviation: μg/L, micrograms per liter]

CAS No. Chemical name

Plan 

initiation 

level

(μg/L)

Not analyzed in this study—Continued

1024-57-3 Heptachlor epoxide 0.2

32241-08-0 Heptachloronaphthalene 0.4

25637-99-4 Hexabromocyclodecane (HBCD) 7

319-84-6 alpha-Hexachlorocyclohexane 0.006

319-85-7 beta-Hexachlorocyclohexane 0.04

58-89-9 gamma-Hexachlorocyclohexane (Lindane) 0.2

1335-87-1 Hexachloronaphthalene 1.4

70-30-4 Hexachlorophene 2

465-73-6 Isodrin 0.6

330-55-2 Linuron 0.09

832-69-9 1-Methylphenanthrene 0.7

2381-21-7 1-Methylpyrene 20

2385-85-5 Mirex 0.001

15323-35-0 Musk indane 10

81-14-1 Musk ketone 30

145-39-1 Musk tibetene 4

81-15-2 Musk xylene 100

1163-19-5 PBDE-209 0.1

7012-37-5 PCB-28 0.5

32598-13-3 PCB-77 0.5

70362-50-4 PCB-81 0.5

32598-14-4 PCB-105 0.5

74472-37-0 PCB-114 0.5

65510-44-3 PCB-123 0.5

57465-28-8 PCB-126 0.5

35065-27-1 PCB-153 0.5

38380-08-4 PCB-156 0.5

69782-90-7 PCB-157 0.5

52663-72-6 PCB-167 0.5

32774-16-6 PCB-169 0.5

39635-31-9 PCB-189 0.5

608-93-5 Pentachlorobenzene 6

1321-64-8 Pentachloronaphthalene 4

375-85-9 Perfluoroheptanoic acid (PFHpA) 300

375-95-1 Perfluorononanoic acid (PFNA) 1

754-91-6 Perfluorooctane sulfonamide (PFOSA) 0.2

1763-23-1 Perfluorooctane sulfonic acid (PFOS) 300

335-67-1 Perfluorooctanoic acid (PFOA) 24

2062-78-4 Pimozide 3

67747-09-5 Prochloraz 2

80214-83-1 Roxithromycin 710

92-94-4 p-Terphenyl 11

79-94-7 Tetrabromobisphenol A (TBBPA) 980

1335-88-2 Tetrachloronaphthalene 14

1321-65-9 Trichloronaphthalene 43

95-95-4 2,4,5-Trichlorophenol 18

732-26-3 2,4,6-Tris-(1,1-dimethylethyl)phenol) 6
46 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Table 27. Oregon Senate Bill 737 priority persistent pollutants detected in wastewater-treatment-plant (WWTP) effluent, Columbia 

River Basin, Washington and Oregon, 2008–09.

[CAS No.: Chemical Abstract Service Registry Number® is a Registered Trademark of the American Chemical Society. CAS recommends the verification 

of the CASRNs through CAS Client ServicesSM. Plan initiation level (PIL; SB 737): From Oregon Department of Environmental Quality (2010a).

Abbreviatons: μg/L, micrograms per liter; E, estimated]

CAS No. Chemical name

Plan 

initiation level 

(μg/L)

Number of 

WWTPs with 

detections

Number of WWTPs 

with detections

greater than PIL

Range of 

detections

(μg/L)

WWTPs 

with detections

Detected in WWTP effluent at concentrations greater than the PIL

57-88-5 Cholesterol 0.06 9 9 Present–E 6.3 see table 9

360-68-9 Coprostanol 0.04 9 9 Present–E 5.8 see table 9

120-12-7 Anthracene 0.01 1 1 Present St. Helens, see table 9

206-44-0 Fluoranthene 0.04 1 1 E 0.11 Wenatchee, see table 9

Detected in WWTP effluent at concentrations less than the PIL

5103-71-9 cis-Chlordane 2 9 0 0.00002–0.00019 see table 13

5103-74-2 trans-Chlordane 2 9 0 0.00001–0.00019 see table 13

2921-88-2 Chlorpyrifos 0.04 4 0 0.0000–0.00043 see table 13

60-57-1 Dieldrin 0.002 5 0 0.00001–0.00017 see table 13

120068-37-3 Fipronil 15 7 0 Present–E 0.13 see tables 13 and 14

1222-05-5 Galaxolide (HHCB) 29 9 0 0.38–2.5 see table 9

118-74-1 Hexachlorobenzene (HCB) 1 1 0 Present Umatilla, see table 13

22967-92-6 Methylmercury 0.004 7 0 0.00006–0.0004 see table 15

5103-73-1 cis-Nonachlor 2 2 0 Present –0.00001 see table 13

39765-80-5 trans-Nonachlor 2 8 0 Present–0.0001 see table 13

5436-43-1 PBDE-47 0.7 9 0 Present see table 13

60348-60-9 PBDE-99 0.7 9 0 Present–0.0048 see table 13

189084-64-8 PBDE-100 0.7 9 0 Present–0.0016 see table 13

68631-49-2 PBDE-153 1 9 0 0.00006–0.0004 see table 13

37680-73-2 PCB-101 0.5 1 0 Present Longview, see table 13

35065-29-3 PCB-180 0.5 3 0 0.00001–0.00002 see table 13

1825-21-4 Pentachloroanisole 35 5 0 Present –0.00085 see table 13

85-01-8 Phenanthrene 0.4 1 0 Present St. Helens, see table 9

129-00-0 Pyrene 0.03 3 0 Present see table 9

83-46-5 beta-Sitosterol 25 9 0 E 0.79–E 3.2 see table 9

83-45-4 beta-Stigmastanol 75 5 0 Present–E 1.1 see table 9

3380-34-5 Triclosan 70 8 0 Present–0.76 see tables 9 and 13

1582-09-8 Trifluralin 1.1 3 0 Present–0.00002 see table 13
Future Directions 47

The other two compounds from the SB 737 list that were 

detected in this study at concentrations that were greater than 

the PILs are both sterols that are ubiquitous in wastewater. 

Cholesterol is a structural component of mammalian cell 

walls and is transported in the blood plasma of all animals. 

Its effects in the aquatic environment are not understood. 

Coprostanol is a metabolite of cholesterol excreted in 

fecal matter from mammals and is, therefore, detected in 

urban effluents. It can be accumulated by organisms living 

in municipal effluent outfalls and has been determined to 

have estrogenic effects in freshwater mussels (Gagné and 

others, 2001). According to ODEQ, “Research suggests that 

coprostanol has an affinity to estradiol-binding sites and ... 

large amounts may pose a threat to aquatic invertebrates” 

(Oregon Department of Environmental Quality, 2010a). 

A large number of the AOCs and pharmaceuticals 

analyzed in WWTP-effluent samples in this study were 

detected, yet only 27 of the 42 compounds on the SB 737 

persistent pollutants list that were analyzed in this study 

were detected in these WWTP-effluent samples. The reason 

for this dichotomy is that many of the contaminants on the 

persistent pollutant list are PAHs, metals, and currently used 

pesticides—all compounds that are likely to be detected in 

stormwater but not necessarily wastewater. To illustrate this 

point, 45 of the 50 compounds on the persistent pollutant list 

that were analyzed in stormwater-runoff samples in this study 

were detected; however, SB 737 does not apply to stormwater. 

One category that is absent from the persistent pollutant list 

is pharmaceuticals, the contaminant class that many people 

associate with WWTP effluent. Sufficient documentation 

about the persistence or bioaccumulative ability of many 

pharmaceuticals is not available to allow consideration for the 

persistent pollutant list. 

Future Directions

This study was intended to serve as a stepping-stone 

for future work. Therefore, it is important to consider how 

the data from this reconnaissance can help inform decisions 

about sampling design and identify information gaps. This 

type of information can be combined to more effectively 

address potential reduction efforts depending on the targeted 

contaminant class. 

Sampling Design

The samples collected in this study were point or 

grab samples designed for an initial characterization of the 

pathways sampled. Through these efforts, it was determined 

that WWTP effluent contains a wide variety of contaminants 

from many different compound classes. No clear pattern of 

detections emerged among the WWTPs based on location, 

population, treatment type, or size of the plant. This type 

of ancillary information could not be used to anticipate the 

type or frequency of detections. Given the various factors 

influencing the composition of the effluent, it would be 

difficult to design a study to explain the expected results for 

WWTP effluent. This pathway can be considered simply as an 

integrator of human activity and used to evaluate the effects 

this activity has on the ecosystem. 

At the Portland WWTP, three samples were collected 

throughout 1 day to examine temporal variability. Given 

the inherent variability in these types of samples, no 

obvious differences throughout the day were noted for most 

compounds. The exception was some of the halogenated 

compounds (PBDEs, herbicides and insecticides, and 

triclosan) that exhibited patterns of lower concentrations in 

the morning with some noon and afternoon concentrations 

roughly two to four times higher (table 13). This finding 

illustrates that a single grab sample may not be adequate to 

characterize the effluent. Time-composited (24-hour) samples 

may provide a better characterization of the contributions 

throughout the day. 

Another sampling technique that provides a timeintegrated sample is the use of passive samplers (Alvarez, 

2010). Passive samplers left in the water for about 30 days 

integrate the sample by accumulating contaminants, 

similar to fish or other aquatic biota in the area. In this 

way, these samples provide a biologically relevant measure 

of the complex mixtures present. Additionally, because 

these samplers integrate over time, the contaminants are 

essentially concentrated into the sampling media, which 

results in increased sensitivity and lower detection limits 

than a traditional water sample. This would be important for 

collecting samples not only from the effluent stream but also 

from the receiving waters, where dilution makes it difficult 

to detect these low concentrations using standard methods 

(table 25). An ideal design for future characterization of 

not only what is being delivered by the WWTP effluent or 

stormwater runoff, but also the fate and transport of these 

contaminants, would combine passive samplers in the waste 

stream and the receiving water, both in the mixing zone and at 

some distance downstream and outside the mixing zone. 
48 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Seasonality is a key factor in characterizing stormwater 

runoff. The length of dry time preceding a runoff event, 

the magnitude and length of the event, and the time of year 

(related to pesticide usage, for example) all may have an 

effect (Sansalone and others, 1998; Flint, 2004). Much less 

is known about seasonality effects on WWTP effluent. Much 

will depend on the type of inputs the WWTP receives. For 

instance, a WWTP receiving wastewater from a cannery or 

fruit-processing facility will see changes in their influent as 

the contributing facilities change their operations. How much 

of an effect this has on the makeup of the effluent could be a 

study objective. Likewise, seasonal changes in prescription 

and over-the-counter medicine use also may be noticeable in 

WWTP effluents. 

The chemical characteristics of the targeted compounds 

often determine how to focus the sampling media. For 

hydrophobic compounds, sampling should be targeted at 

retrieving as much solid material as possible, either through 

sampling unfiltered water or the solids themselves. The 

dissolved phase should not be ignored, however, because most 

compounds are not confined to just one media. The samples 

measured for estrogenicity in this study indicated that the 

hormonally active compounds were likely dissolved in the 

effluent water rather than associated with the solids in the 

effluent (table 11). 

Information Gaps

The affinity that some contaminants have for the solid 

phase rather than the aqueous phase raises questions about 

how many contaminants are sequestered in biosolids during 

the treatment process and what is their ultimate fate. For most 

WWTPs, biosolids are transported to a nearby area and spread 

over the land, many times applied as a fertilizer or nutrient 

treatment for the land. In 2008, USGS researchers determined 

that earthworms collected from fields where biosolids and 

manure had been applied not only picked up drugs and 

perfumes from the soil but also had bioconcentrated these 

compounds in their tissues (Kinney and others, 2008). Once 

these contaminants are spread on the land with the biosolids, 

little is known about the further transport, degradation, or 

ultimate effect of these contaminants on the ecosystem. 

This study focused on two known pathways for 

contaminant transport, but further study could expand 

this focus to incorporate other potential pathways and 

sources. These could include but are not limited to other 

dischargers with an NPDES permit; industries located along 

a contributing stream; hospitals, nursing homes, hospice 

and in-home facilities; or manufacturers of emerging 

contaminants. Further characterization of the land-use types 

and contributions to stormwater-runoff areas also would help 

in designing reduction efforts based on these results. The 

spatial distribution of this study could be expanded to include 

a further extent of the Columbia River Basin, including 

pathways to tributaries.

The aquatic communities living in these receiving waters 

are exposed to complex mixtures of these compounds with 

unknown toxicity. Further research into sublethal effects, 

toxicity, bioaccumulation, and mixture effects is needed to 

further the science of emerging contaminants. 

Summary and Conclusions

Toxic contamination is a significant concern in the 

Columbia River Basin. Many efforts and dollars are focused 

on restoring critical habitat for endangered salmonids and 

other wildlife that depend on the ecosystem; however, 

although physical habitat is a prime consideration in 

restoration decisions, water-quality concerns, specifically 

contamination issues, also can influence these decisions. 

Toxics-reduction efforts are underway to protect the health of 

people, aquatic life, and the ecosystem. 

To successfully reduce toxics and restore critical habitat, 

an understanding of the sources of contaminants is necessary. 

This study was designed to take a first look at two easily 

defined pathways that deliver contaminants to the Columbia 

River, wastewater-treatment-plant (WWTP) effluent and 

stormwater runoff. The resulting data can be used to assess 

the types, number, and magnitude of compounds present 

and to lay the foundation for additional studies and potential 

toxics-reduction activities. 

Nine cities were selected from throughout the Columbia 

River Basin to provide diversity in physical setting, climate 

characteristics, and population density. In downstream order, 

the cities sampled were Wenatchee, Richland, Umatilla, The 

Dalles, Hood River, Portland, Vancouver, St. Helens, and 

Longview throughout Washington and Oregon. These cities 

also were selected because their WWTP effluent and at least 

some part of their stormwater (except Umatilla) is delivered 

directly to the Columbia River. Most samples at the WWTPs 

were collected in December 2008 for anthropogenic organic 

compounds (AOCs), pharmaceuticals, estrogenicity, and 

halogenated compounds. In December 2009, each of these 

WWTPs was revisited to collect samples for the analysis 

of currently used pesticides, mercury, and methylmercury. 

Stormwater samples were collected throughout spring and 

winter storms of 2009 and 2010 from these cities as well 

as additional sites along the lower Willamette River near 

downtown Portland. These samples were analyzed for 

currently used pesticides, halogenated compounds, mercury, 

polycyclic aromatic hydrocarbons (PAHs), trace elements, and 

oil and grease. 
Summary and Conclusions 49

WWTP effluents—Flame retardants (polybrominated 

diphenyl ethers [PBDEs] and others) and steroids were 

consistently detected in WWTP-effluent samples, whereas 

few pesticides or PAHs were detected, except at Longview. 

Concentrations of PBDEs were detected at all sites, and the 

highest concentrations detected were for congeners PBDE‐47, 

PBDE-99, and PBDE-100. No PCBs were detected at most 

WWTPs, except Wenatchee. Longview also was notable 

because it had the greatest number of detections and the 

concentrations were usually among the highest, particularly 

for the personal-care-product compounds. Fourteen 

human‐health pharmaceuticals were analyzed for and all 

but albuterol and warfarin were detected in at least one city. 

Two pharmaceuticals were detected at all of the W sampled, 

carbamazepine and diphenhydramine. The yeast estrogen 

screen, an assay that measures the potential biological effects 

of the mixture of chemicals present in a sample, was used to 

screen each sample for total estrogenicity. The estrogenicity 

levels measured in this study were well above levels that have 

been shown to cause effects in aquatic biota.

Few currently used pesticides were detected in 

WWTP‐effluent samples. The primary compounds detected 

were fipronil and its degradates, which were in samples 

collected from all WWTPs except Wenatchee. Fipronil is 

an insecticide used to control common household pests like 

ants, beetles, cockroaches, and other insects, and can be in 

topical pet-care products used to control fleas. The highest 

total mercury concentrations were measured at The Dalles and 

Vancouver. Both of these concentrations were greater than 

12 ng/L, the chronic criterion for freshwater aquatic life.

Stormwater-runoff—Diverse sources of stormwater 

runoff and the larger amount of suspended sediment present 

in these samples relative to that in WWTP-effluent samples 

resulted in very different results for the stormwater-runoff 

samples. Additionally, localized sources contributed to 

the detection patterns observed in these samples. Of the 

49 halogenated compounds detected in stormwater-runoff 

samples, 45 were detected in the Willamette2-Dec sample, 

which is within the Portland Harbor Superfund area. The 

PBDE concentrations at Willamette2 were roughly double 

those in the Umatilla sample and the PCB concentrations 

at Willamette2 were 20–300 times greater than PCB 

concentrations in any other stormwater-runoff samples. 

Herbicide and insecticide detections in solids filtered from 

stormwater runoff also follow a pattern of high contaminant 

concentrations in samples with high suspended-sediment 

concentrations—particularly from Umatilla, Vancouver, and 

Willamette2. Detections for several pesticides and PCBs 

from the Willamette2 site in December and May exceeded 

chronic freshwater-quality criteria. Although many of these 

concentrations are low (less than 1 microgram per liter), 

mixtures of some of these pesticides have been determined to 

have synergistic and additive effects on salmon health when 

they occur together.

The 10 trace elements measured in filtered and unfiltered 

stormwater runoff in this study were detected consistently 

through all samples. Arsenic, cadmium, copper, nickel, 

selenium, and zinc tended to transport more readily in 

the dissolved phase, whereas chromium, lead, mercury, 

and silver were more often detected in the solid phase. 

Chronic and sometimes acute freshwater-quality criteria for 

cadmium, copper, lead, and zinc were all exceeded in several 

stormwater-runoff samples. These concentrations, particularly 

for copper, chromium, and zinc, also were potentially high 

enough to cause health effects in aquatic biota. The Willamette 

stormwater-runoff sites in the Portland Harbor area, as well 

as Vancouver2, had concentrations of total mercury greater 

than or equal to the chronic criterion for freshwater aquatic 

life (12 ng/L).

Implications for the Columbia River Basin—

Instantaneous loadings were calculated for four compounds 

detected in WWTP-effluent samples—diphenhydramine, 

trimethoprim, Galaxolide, and nonylphenol compounds—to 

estimate the potential contribution to the Columbia River from 

the studied WWTPs. The instantaneous loads for the Portland 

WWTP were consistently much greater than for any other 

plant because the effluent discharge from the Portland WWTP 

is much greater than for any other plant, discharging five times 

more than the next largest WWTP, in The Dalles. The resulting 

concentrations in the Columbia River from these contributions 

were calculated. Most of these concentrations were small and 

would not be detectable using standard sampling techniques. 

These calculations illustrate that the Columbia River is able 

to “absorb” a variety of inputs because of its ability to dilute. 

Nonetheless, although the calculated concentrations are small 

in the context of the entire river, the local effect of these 

continuous inputs in the mixing zone is understudied. The 

aquatic biota inhabiting these areas may be exposed to higher 

concentrations than in other areas.

Comparison to Oregon Senate Bill (SB) 737—As part of 

the SB 737 process to identify persistent pollutants and reduce 

concentrations entering Oregon’s waterways, the Oregon 

Department of Environmental Quality (ODEQ) was tasked 

with developing a list of persistent pollutants that have a 

documented effect on human health, wildlife, and aquatic life. 

The 52 largest WWTPs in Oregon sent samples to the ODEQ 

laboratory to be analyzed for these pollutants, and the results 

were compared to plan initiation levels (PILs) developed to 

decide when action is required to reduce the presence of these 

pollutants in the effluents. Only four compounds analyzed 

for in this study—fluoranthene, anthracene, cholesterol, and 

coprostanol—exceeded the corresponding PILs. Many of 

the AOCs and pharmaceuticals analyzed in WWTP-effluent 

samples collected during this study were detected; however, 

these samples contained only 27 of the 42 compounds on the 

SB 737 persistent pollutants list that were analyzed for in 

this study. The reason for this dichotomy is that many of the 

contaminants on the persistent pollutant list are PAHs, metals, 

and currently used pesticides—all compounds that are likely 

to be detected in stormwater but not necessarily wastewater.
50 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Future directions—This study was intended to serve as a 

precursor for future work. The study results show that WWTP 

effluent contains a wide variety of contaminants from many 

compound classes. Given the variety of factors influencing 

the composition of the effluent, it would be difficult to design 

a study to explain the expected results for WWTP effluent. It 

is preferable to consider this pathway simply as an integrator 

of human activity and focus on minimizing the effects it has 

on the ecosystem. Seasonality was not addressed in this study 

design. The large number of hydrophobic compounds that 

were detected in these effluents indicates that the biosolids 

from these WWTPs may be potentially significant sources of 

these contaminants to the ecosystem.

Stormwater runoff acts as an integrator of human 

activities and can be a source of various compounds to 

aquatic ecosystems. The inputs from stormwater runoff are 

more sporadic than the continual input of WWTP effluents, 

but their potentially large contributions during short periods 

can still have an effect on biota that inhabit mixing zones in 

the receiving waters. Toxics-reduction efforts will be more 

effective when contaminant occurrence and distribution data 

are coupled with land-use information from the stormwater 

catchments that drain to the Columbia River.

Data from this study and others like it can provide a 

useful framework for directing future work on identifying and 

reducing contaminant concentrations in the Columbia River 

Basin. Wastewater-treatment plant effluent and stormwater 

runoff are two pathways for contaminants to reach the 

receiving waters, but there are other understudied pathways. 

The results from this study provide a starting point for future 

work to continue understanding the presence of contaminants 

in the environment, develop research to characterize the 

effects of these contaminants on aquatic life, and prioritize 

future toxic-reduction efforts. 

Acknowledgments

Special thanks to (1) each city mentioned for allowing 

access to the WWTP effluent and for assistance in locating 

stormwater-runoff locations; (2) Emily Rauch, Brian Cimyotti, 

and Rachael Pecore for volunteering and helping to collect 

stormwater samples in remote locations; (3) Lauren Goldberg 

and Brett VandenHeuvel (Columbia Riverkeeper) and Mark 

Riskedahl (Northwest Environmental Defense Center) for 

their support of this project and help gathering valuable 

information; and (4) Tiffany Rae Jacklin, Daniel Wise, Esther 

Duggan, Whitney Temple, Henry Johnson, and David Piatt (all 

USGS) for their help with sampling and processing.

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Plant, Oregon, December 2009.
Appendix A 57

Appendix A. – Methods, Reporting Limits, and Analyte Information

Table A1. Reporting limits and possible uses or sources of halogenated compounds analyzed in solids filtered from wastewatertreatment-plant effluent or stormwater runoff, Columbia River Basin, Washington and Oregon, 2008–10.

[Shading indicates a detection in wastewater-treatment-plant effluent in this study; bold type indicates a detection in stormwater runoff in this study. CAS No.:

Chemical Abstract Service Registry Number® is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs 

through CAS Client ServicesSM. Reporting limit: Reported in nanograms; divide the reporting limit by the volume of water filtered for each sample to get the 

reporting limit in nanograms per liter. Possible compound uses or sources: From Steve Zaugg, U.S. Geological Survey, written commun., December 2008. 

Abbreviation: NA, not available]

Analyte Parameter

code

CAS

No.

Reporting 

limit

Possible compound 

uses or sources

Polybrominated diphenyl ethers (PBDEs) and other flame retardants

Bis(hexachlorocyclopentadieno) cyclooctane 

 [Dechlorane Plus]

65220 13560-89-9 1 Chlorinated flame retardant

1,2-Bis(2,4,6-tribromophenoxy) ethane 

 [Firemaster 680]

64868 37853-59-1 0.1 Brominated flame retardant

Pentabromotoluene 64867 87-83-2 1 Brominated flame retardant

2,2’,4,4’-Tetrabromodiphenylether (PBDE-47) 63166 5436-43-1 0.2 Textile and electronic flame retardant

2,3’,4,4’-Tetrabromodiphenyl ether (PBDE-66) 64852 189084-61-5 0.1 Textile and electronic flame retardant

2,3’,4’,6-Tetrabromodiphenyl ether (PBDE-71) 64853 189084-62-6 0.1 Textile and electronic flame retardant

2,2’,3,4,4’-Pentabromodiphenyl ether (PBDE-85) 64854 182346-21-0 0.1 Textile and electronic flame retardant

2,2’,4,4’,5-Pentabromodiphenyl ether (PBDE-99) 64855 60348-60-9 0.2 Textile and electronic flame retardant

2,2’,4,4’,6-Pentabromodiphenyl ether (PBDE-100) 64856 189084-64-8 0.1 Textile and electronic flame retardant

2,2’,3,4,4’,5’-Hexabromodiphenyl ether (PBDE-138) 64857 182677-30-1 0.1 Textile and electronic flame retardant

2,2’,4,4’,5,5’-Hexabromodiphenylether (PBDE-153) 64858 68631-49-2 0.1 Textile and electronic flame retardant

2,2’,4,4’,5,6’-Hexabromodiphenyl ether (PBDE-154) 64859 207122-15-4 0.1 Textile and electronic flame retardant

2,2’,3,4,4’,5’,6-Heptabromodiphenyl ether 

 (PBDE-183)

64860 207122-16-5 0.1 Textile and electronic flame retardant

Polychlorinated biphenyls (PCBs)

PCB-49 64725 41464-40-8 2 PCB congener

PCB-52 64726 35693-99-3 1 PCB congener

PCB-70 64727 32598-11-1 2 PCB congener

PCB-101 64729 37680-73-2 1 PCB congener

PCB-110 64730 38380-03-9 1 PCB congener

PCB-118 64731 31508-00-6 0.1 PCB congener

PCB-138 64732 35065-28-2 0.1 PCB congener

PCB-146 64733 51908-16-8 0.1 PCB congener

PCB-149 64734 38380-04-0 1 PCB congener

PCB-151 64735 52663-63-5 0.1 PCB congener

PCB-170 64736 35065-30-6 0.1 PCB congener

PCB-174 64737 38411-25-5 0.1 PCB congener

PCB-177 64738 52663-70-4 0.1 PCB congener

PCB-180 64739 35065-29-3 0.1 PCB congener

PCB-183 64740 52663-69-1 0.1 PCB congener

PCB-187 64741 52663-68-0 0.1 PCB congener

PCB-194 64742 35694-08-7 0.1 PCB congener

PCB-206 64743 40186-72-9 0.1 PCB congener
58 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Analyte Parameter

code

CAS

No.

Reporting 

limit

Possible compound 

uses or sources

Herbicides and insecticides

Benfluralin 63265 1861-40-1 0.2 Dinitroaniline herbicide

cis-Chlordane 63271 5103-71-9 0.2 Organochlorine insecticide

trans-Chlordane 63272 5103-74-2 0.2 Organochlorine insecticide

Chlorpyrifos 63273 2921-88-2 0.2 Organophosphate insecticide

Cyfluthrin 63279 68359-37-5 0.2 Insecticide

lambda-Cyhalothrin 63280 91465-08-6 0.2 Insecticide

Dacthal (DCPA) 63282 1861-32-1 0.2 Phenoxyacid herbicide

p,p′-dichlorodiphenyldichloroethane (DDD) 63346 72-54-8 2 Legacy pesticide

p,p′-dichlorodiphenyldichloroethylene (DDE) 63347 72-55-9 1 Legacy pesticide

p,p′-dichlorodiphenyltrichloroethane (DDT) 63345 50-29-3 4 Legacy pesticide

Desulfinylfipronil 63316 NA 0.1 Fipronil degradate

Dieldrin 63289 60-57-1 0.1 Organochlorine insecticide

alpha-Endosulfan 63259 959-98-8 0.2 Organochlorine insecticide

Fipronil 63313 120068-37-3 0.1 Insecticide

Fipronil sulfide 63314 120067-83-6 0.1 Fipronil degradate

cis-Nonachlor 63338 5103-73-1 0.1 Insecticide

trans-Nonachlor 63339 39765-80-5 0.1 Insecticide

Oxychlordane 64866 27304-13-8 1 Insecticide

Oxyfluorfen 63341 42874-03-3 4 Herbicide

Pendimethalin 63353 40487-42-1 1 Herbicide

Pentachloroanisole (Chloridazon) 64119 1825-21-4 0.1 Herbicide

Pentachloronitrobenzene 63650 82-68-8 0.1 Organochlorine herbicide

Tefluthrin 63377 79538-32-2 0.5 Insecticide

Trifluralin 63390 1582-09-8 0.2 Dinitroaniline herbicide

Other compounds

Hexachlorobenzene (HCB) 63631 118-74-1 0.1 Organochlorine fungicide

Methoxy triclosan 63639 1000766 6 Triclosan degradate

Octachlorostyrene 65217 29082-74-4 1 Combustion by-product

Tetradifon 63665 116290 0.2 Acaricide

Triclosan 63232 3380-34-5 4 Anti-bacterial agent

Table A1. Reporting limits and possible uses or sources of halogenated compounds analyzed in solids filtered from wastewatertreatment-plant effluent or stormwater runoff, Columbia River Basin, Washington and Oregon, 2008–10.—Continued

[Shading indicates a detection in wastewater-treatment-plant effluent in this study; bold type indicates a detection in stormwater runoff in this study. CAS No.:

Chemical Abstract Service Registry Number® is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs 

through CAS Client ServicesSM. Reporting limit: Reported in nanograms; divide the reporting limit by the volume of water filtered for each sample to get the 

reporting limit in nanograms per liter. Possible compound uses or sources: From Steve Zaugg, U.S. Geological Survey, written commun., December 2008. 

Abbreviation: NA, not available]
Table A2 59

Table A2. Reporting limits and possible uses or sources of anthropogenic organic compounds analyzed in unfiltered wastewater-treatment-plant effluent, Columbia River Basin, Washington and Oregon, 2008–09.[Shading indicates a detection in wastewater-treatment-plant effluent in this study. CAS No.: Chemical Abstract Service Registry Number® is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs through CAS Client ServicesSM. Method detection limit and Reporting limit: Values are in micrograms per liter. EDP (endocrine-disrupting potential) and Possible 

compound uses or sources: From Zaugg and others (2006). Abbreviations: K, known; S, suspected; >, greater than; –, no data; NA, not available]

Analyte Parameter code CAS No. Method detection limit Reporting limit EDP Possible compound uses or sources

Detergent metabolites

4-Cumylphenol 62808 599-64-4 0.13 0.2 K Nonionic detergent metabolite

para-Nonylphenol (total) 62829 84852-15-3 1.2 1.6 K Nonionic detergent metabolite

4-Nonylphenol monoethoxylate (sum of all isomers) [NP1EO] 61704 NA 1.35 1.6 K Nonionic detergent metabolite

4-Nonylphenol diethoxylate (sum of all isomers) [NP2EO] 61703 NA 1.2 3.2 K Nonionic detergent metabolite

4-n-Octylphenol 62809 1806-26-4 0.11 0.2 K Nonionic detergent metabolite

4-tert-Octylphenol 62810 140-66-9 0.11 0.4 K Nonionic detergent metabolite

4-tert-Octylphenol diethoxylate (OP2EO) 62486 NA 0.05 10.32 K Nonionic detergent metabolite

4-tert-Octylphenol monoethoxylate (OP1EO) 62485 NA 0.5 1 K Nonionic detergent metabolite

Flame retardants

2,2′,4,4'-Tetrabromodiphenyl ether (PBDE-47) 63147 5436-43-1 0.11 0.3 – Widely used brominated flame retardant

Tri(2-butoxyethyl)phosphate 62830 78-51-3 0.05 0.2 – Flame retardant

Tri(2-chloroethyl)phosphate 62831 115-96-8 0.08 0.2 S Plasticizer, flame retardant

Tri(dichlorisopropyl)phosphate 61707 13674-87-8 0.05 0.2 S Flame retardantTributyl phosphate 62832 126-73-8 0.11 0.2 – Antifoaming agent, flame retardant

Miscellaneous - antioxidants, solvents, or multiple uses

Anthraquinone 62813 84-65-1 0.08 0.2 – Manufacturing of dye/textures, seed treatment, bird repellant

Bromoform 32104 75-25-2 0.03 0.2 – Wastewater ozination byproduct, military/explosives

3-tert-Butyl-4-hydroxyanisole (BHA) 61702 25013-16-5 0.16 0.2 K Antioxidant, general preservative

Caffeine 81436 58-08-2 0.06 0.2 – Beverages, diuretic, very mobile/biodegradable

Carbazole 77571 86-74-8 0.12 0.2 – Insecticide, manufacturing of dyes, explosives, and lubricants

Cotinine 61945 486-56-6 0.29 0.8 – Primary nicotine metabolite

para-Cresol 77146 106-44-5 0.08 0.2 S Wood preservative

Isophorone 34408 78-59-1 0.08 0.2 – Solvent for lacquer, plastic, oil, silicon, resin

Isopropylbenzene (cumene) 77223 98-82-8 0.02 0.2 – Manufacturing of phenol/acetone, fuels and paint thinner

d-Limonene 62819 5989-27-5 0.02 0.2 – Fungicide, antimicrobial, antiviral, fragrance in aerosols

5-Methyl-1H-benzotriazole 61944 136-85-6 0.35 1.6 – Antioxidant in antifreeze and deicers

Pentachlorophenol 39032 87-86-5 0.33 0.8 S Herbicide, fungicide, wood preservative, termite controlTetrachloroethylene 34475 127-18-4 0.22 0.4 – Solvent, degreaser, veterinary antihelmintic
60 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 Analyte Parameter code CAS No. Method detection limit Reporting limit EDP Possible compound uses or sources Personal care products Acetophenone 62811 98-86-2 0.07 0.4

– Fragrance in detergent and tobacco, flavor in beverages

Benzophenone 62814 119-61-9 0.1 0.2 S Fixative for perfumes and soaps

Camphor 62817 76-22-2 0.09 0.2

– Flavor, odorant, ointments

1,4-Dichlorobenzene 34571 106-46-7 0.03 0.2 S Moth repellent, fumigant, deodorant

Galaxolide (hexahydrohexamethylcyclopentabenzopyran, 

HHCB) 

62823 1222-05-5 0.11 0.2

– Musk fragrance (widespread usage) persistent in ground water

Indole 62824 120-72-9 0.08 0.2

– Pesticide inert ingredient, fragrance in coffee

Isoborneol 62825 124-76-5 0.05 0.2

– Fragrance in perfumery, in disinfectants

Isoquinoline 62826 119-65-3 0.09 0.2

– Flavors and fragrances

Menthol 62827 89-78-1 0.05 0.2

– Cigarettes, cough drops, liniment, mouthwash

3-Methyl-1H-indole (skatol) 62807 83-34-1 0.07 0.2

– Fragrance, stench in feces and coal tar

Methyl salicylate 62828 119-36-8 0.07 0.2

– Liniment, food, beverage, ultraviolet-absorbing lotion

Phenol 34694 108-95-2 0.07 0.2

– Disinfectant, manufacturing of several products, leachate

Tonalide (acetyl-hexamethyl-tetrahydronaphthalene, AHTN) 62812 21145-77-7 0.11 0.2

– Musk fragrance (widespread usage) persistent in ground water

Triclosan 61708 3380-34-5 0.09 0.2 S Disinfectant, antimicrobial (concern for acquired microbial resistance)

Triethyl citrate (ethyl citrate) 62833 77-93-0 0.07 0.2

– Cosmetics, pharmaceuticals

Pesticides

Atrazine 39630 1912-24-9 0.08 0.2

K Selective triazine herbicide

Bromacil 30234 314-40-9 0.1 0.8 S General-use herbicide, >80 percent noncrop usage on grass/brush

Carbaryl 39750 63-25-2 0.13 0.2

K Insecticide, crop and garden uses, low persistence

Chlorpyrifos 38932 2921-88-2 0.12 0.2

K Insecticide, domestic pest/termite control (domestic use restricted as 

of 2001)

Diazinon 39570 333-41-5 0.11 0.2

K Insecticide, > 40 percent nonagricultural usage, ants, flies

3,4-Dichlorophenyl isocyanate 63145 102-36-3 0.06 1.6

– Degradate of diuron, a noncrop herbicide

Dichlorvos 30218 62-73-7 0.11 0.2 S Insecticide, pet collars; Naled or Trichlorfon degradate

Metalaxyl 4254 57837-19-1 0.13 0.2

– Herbicide, fungicide, general-use pesticide, mildew, blight, pathogens, 

golf/turf

Metolachlor 82612 51218-45-2 0.12 0.2

– Herbicide, general-use pesticide, indicator of agricultural drainage

N,N-diethyl-meta-toluamide (Deet) 61947 134-62-3 0.12 0.2

– Insecticide, urban uses, mosquito repellent

Prometon 39056 1610-18-0 0.08 0.2

– Herbicide (noncrop only), applied prior to blacktop

Table A2. Reporting limits and possible uses or sources of anthropogenic organic compounds analyzed in unfiltered wastewater-treatment-plant effluent, Columbia River Basin, Washington and Oregon, 2008–09.—Continued[Shading indicates a detection in wastewater-treatment-plant effluent in this study. CAS No.: Chemical Abstract Service Registry Number® is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs through CAS Client ServicesSM. Method detection limit and Reporting limit: Values are in micrograms per liter. EDP (endocrine-disrupting potential) and 

Possible compound uses or sources: From Zaugg and others (2006). Abbreviations: K, known; S, suspected; >, greater than; –, no data; NA, not available]
Table A2 61

Analyte Parameter code CAS No. Method detection limit Reporting limit EDP Possible compound uses or sources

Plasticizers

Bisphenol A 62816 80-05-7 0.22 0.4 K Manufacturing of polycarbonate resins, antioxidant, flame retardant

Diethyl phthalate (DEP) 34336 84-66-2 0.1 0.2 K Plasticizer for polymers and resins

bis-(2-Ethylhexyl) phthalate (DEHP) 39100 117-81-7 0.85 2 K Plasticizer for polymers and resins, pesticide inert

Triphenyl phosphate 62834 115-86-6 0.1 0.2 – Plasticizer, resin, wax, finish, roofing paper, flame retardant

Polycyclic aromatic hydrocarbons (PAHs)

Anthracene 34220 120-12-7 0.08 0.2 – Wood preservative, component of tar, diesel, or crude oil, combustion 

product

Benzo(a)pyrene 34247 50-32-8 0.06 0.2 K Regulated polycyclic aromatic hydrocarbon (PAH), used in cancer 

research, combustion product

2,6-Dimethylnaphthalene 62805 581-42-0 0.05 0.2 – Present in diesel/kerosene (trace in gasoline)

Fluoranthene 34376 206-44-0 0.08 0.2 – Component of coal tar, asphalt (only traces in gasoline or diesel fuel), 

combustion product

1-Methylnaphthalene 81696 90-12-0 0.03 0.2 – 2–5 percent of gasoline, diesel fuel, or crude oil

2-Methylnaphthalene 30194 91-57-6 0.03 0.2 – 2–5 percent of gasoline, diesel fuel, or crude oil

Naphthalene 34696 91-20-3 0.03 0.2 – Fumigant, moth repellent, major component (about 10 percent) of 

gasoline

Phenanthrene 34461 85-01-8 0.07 0.2 – Manufacturing of explosives, component of tar, diesel fuel, or crude 

oil, combustion product

Pyrene 34469 129-00-0 0.08 0.2 – Component of coal tar, asphalt (only traces in gasoline or diesel fuel), 

combustion product

Steroids

Cholesterol 62818 57-88-5 0.3 1.6 – Often a fecal indicator, also a plant sterol

3-beta-Coprostanol 62806 360-68-9 0.38 1.6 – Carnivore fecal indicator

beta-Sitosterol 62815 83-46-5 0.11 1.6 – Plant sterol

beta-Stigmastanol 61948 19466-47-8 0.22 1.7 – Plant sterol

1The reporting limit for 4-tert-Octylphenol diethoxylate (OP2EO) changed to 0.5 micrograms per liter in 2009.

Table A2. Reporting limits and possible uses or sources of anthropogenic organic compounds analyzed in unfiltered wastewater-treatment-plant effluent, Columbia River Basin, Washington and Oregon, 2008–09.—Continued[Shading indicates a detection in wastewater-treatment-plant effluent in this study. CAS No.: Chemical Abstract Service Registry Number® is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs through CAS Client ServicesSM. Method detection limit and Reporting limit: Values are in micrograms per liter. EDP (endocrine-disrupting potential) and 

Possible compound uses or sources: From Zaugg and others (2006). Abbreviations: K, known; S, suspected; >, greater than; –, no data; NA, not available]
62 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 Table A3. Reporting limits and intended uses of pharmaceuticals analyzed in filtered wastewater-treatment-plant effluent, Columbia River Basin, Washington and Oregon, 2008–09. [Shading indicates a detection in wastewater-treatment-plant effluent in this study. CAS No.: Chemical Abstract Service Registry Number® is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs through CAS Client ServicesSM. Method detection limit and Reporting limit: Values are in micrograms per liter. Common name and Intended use: From Rounds and others, 2009; Symbol: –, not applicable] Analyte CAS No. Method detection limit Reporting limit Common name Intended use 2008 2009 2008 2009 Acetaminophen 103-90-2 0.04 0.06 0.08 0.12 Tylenol® Analgesic Albuterol 18559-94-9 0.03 0.04 0.06 0.08 Ventolin®, AiromirTM MDI Bronchodilator (for asthma) Caffeine 58-08-2 0.1 0.03 0.2 0.06 NoDoz® Stimulant Carbamazepine 298-46-4 0.02 0.03 0.04 0.06 Epitol®, Tegretol® Anticonvulsant; antimanic (mood stabilizer) Codeine 76-57-3 0.02 0.023 0.04 0.046 Robitussin® AC Opioid narcotic; cough suppressant Cotinine 486-56-6 0.01 0.019 0.026 0.038

– Metabolite of nicotine

Dehydronifedipine 67035-22-7 0.04 0.04 0.08 0.08

– Metabolite and photodegradation product of nifedipine (arterial dilator; 

antihypertensive)

Diltiazem 42399-41-7 0.04 0.03 0.08 0.06 Cardizem® Antianginal; antiarrhythmic; antihypertensive

1,7-Dimethylxanthine 611-59-6 0.06 0.05 0.12 0.1

– Metabolite of caffeine

Diphenhydramine 147-24-0 0.02 0.018 0.04 0.036 Benadryl®, Allerdryl Antihistamine; sedative

Sulfamethoxazole 723-46-6 0.08 0.08 0.16 0.16 BactrimTM, Septra® 

(component)

Antibiotic; antibacterial

Thiabendazole 148-79-8 0.03 0.03 0.06 0.06 Arbotect®, Mertect® Systemic antifungal; livestock antiparisitic

Trimethoprim 738-70-5 0.01 0.017 0.02 0.034 Bactrim, Septra (component) Antibiotic; antibacterial

Warfarin 81-81-2 0.05 0.04 0.1 0.08 Coumadin® Anticoagulant
Table A4 63

Table A4. Reporting limits, uses, and classes of currently used pesticides and degradates analyzed in filtered wastewater-treatment-plant effluent or stormwater runoff, Columbia River Basin, Washington and Oregon, 2009–10.[Shading indicates a detection in wastewater-treatment-plant effluent; bold type indicates a detection in stormwater runoff in this study. CAS No.: Chemical Abstract Service Registry Number® is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs through CAS Client ServicesSM. Method detection limit and Reporting limit: Values are in micrograms per liter. 

Abbreviations: NA, not available; D, degradate; Def, defoilant; F, fumigant; Fun, fungicide; H, herbicide; I, insecticide; N, nematocide; –, not applicable]

Analyte Parameter code CAS No.

Method detection limit Reporting limit

Use Class Parent compound February– September 

2009

October 2009–

June 2010

February–

September 

2009

October 2009–

June 2010

Fungicides

3,5-Dichloroaniline 61627 626-43-7 0.002 0.0015 0.004 0.003 D Amide Iprodione

Iprodione 61593 36734-19-7 0.007 0.007 0.014 0.014 Fun Amide –

Metalaxyl 61596 57837-19-1 0.003 0.003 0.007 0.007 Fun Acylalanine –

Myclobutanil 61599 88671-89-0 0.005 0.005 0.01 0.01 Fun Triazole –

cis-Propiconazole 79846 60207-90-1 0.003 0.003 0.006 0.006 Fun Triazole –

trans-Propiconazole 79847 60207-90-1 0.01 0.01 0.02 0.02 Fun Triazole –

Tebuconazole 62852 107534-96-3 0.01 0.01 0.02 0.02 Fun Triazole –

Herbicides and degradates

Acetochlor 49260 34256-82-1 0.005 0.005 0.01 0.01 H Chloroacetamide –

Alachlor 46342 15972-60-8 0.004 0.004 0.008 0.008 H Chloroacetamide –

Atrazine 39632 1912-24-9 0.004 0.004 0.007 0.007 H Triazine –

Benfluralin 82673 1861-40-1 0.007 0.007 0.014 0.014 H Dinitroaniline –

2-Chloro-2,6-diethylacetanilide 61618 6967-29-9 0.005 0.005 0.01 0.01 D Chloroacetamide Alachlor

2-Chloro-4-isopropylamino-6-amino-s-triazine (CIAT) 04040 6190-65-4 0.007 0.007 0.014 0.014 D Triazine Atrazine

4-Chloro-2-methylphenol 61633 1570-64-5 0.0025 0.002 0.005 0.0032 D Chlorophenoxy acid MCPA, MCPB

Cyanazine 04041 21725-46-2 0.02 0.011 0.04 0.022 H Triazine –

DCPA (Dacthal) 82682 1861-32-1 0.003 0.0038 0.006 0.0076 H Organochlorine –

3,4-Dichloroaniline 61625 95-76-1 0.002 0.0021 0.004 0.0042 D Phenyl urea, 

Chloroacetamide

Diuron, Propanil, 

Linuron, Neburon

2,6-Diethylaniline 82660 579-66-8 0.003 0.003 0.006 0.006 D Chloroacetamide Alachlor

S-Ethyl dipropyl thiocarbamate 

 (EPTC)

82668 759-94-4 0.001 0.001 0.002 0.002 H Thiocarbamate –

2-Ethyl-6-methylaniline 61620 24549-06-2 0.0049 0.0049 0.010 0.0098 D Chloroacetamide Metolachlor

Hexazinone 04025 51235-04-2 0.004 0.004 0.008 0.008 H Triazine –

Metolachlor 39415 51218-45-2 0.007 0.007 0.014 0.014 H Chloroacetamide –

Metribuzin 82630 21087-64-9 0.008 0.006 0.016 0.012 H Triazine –

Molinate 82671 2212-67-1 0.001 0.0013 0.002 0.0026 H Thiocarbamate –

Oxyfluorfen 61600 42874-03-3 0.003 0.005 0.006 0.01 H Diphenyl ether –

Pendimethalin 82683 40487-42-1 0.006 0.006 0.012 0.012 H Dinitroaniline –

Prometon 04037 1610-18-0 0.006 0.006 0.012 0.012 H Triazine –

Prometryn 04036 7287-19-6 0.003 0.003 0.006 0.006 H Triazine –

Propanil 82679 709-98-8 0.007 0.005 0.014 0.01 H Chloroacetamide –
64 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 Analyte Parameter code CAS No. Method detection limit Reporting limit Use Class Parent compound February– September 2009 October 2009– June 2010 February– September 2009 October 2009– June 2010 Herbicides and degradates—Continued Propyzamide 82676 23950-58-5 0.002 0.0018 0.004 0.0036

H Amide

–

Simazine 04035 122-34-9 0.005 0.003 0.01 0.006

H Triazine

–

Tebuthiuron 82670 34014-18-1 0.01 0.014 0.02 0.028

H Phenyl urea

–

Terbuthylazine 04022 5915-41-3 0.003 0.003 0.006 0.006

H Triazine

–

Thiobencarb 82681 28249-77-6 0.008 0.008 0.016 0.016

H Thiocarbamate

–

Trifluralin 82661 1582-09-8 0.006 0.009 0.012 0.018

H Dinitroaniline

–

Insecticides and degradates

Azinphos-methyl 82686 86-50-0 0.06 0.06 0.12 0.12 I Organophosphate

–

Azinphos-methyl-oxon 61635 961-22-8 0.021 0.021 0.042 0.042

D Organophosphate Azinphos-methyl

Carbaryl 82680 63-25-2 0.1 0.03 0.2 0.06 I Carbamate

–

Carbofuran 82674 1563-66-2 0.03 0.03 0.06 0.06 I Carbamate

–

Chlorpyrifos 38933 2921-88-2 0.005 0.005 0.01 0.01 I Organophosphate

–

Chlorpyrifos oxygen analog 61636 5598-15-2 0.025 0.025 0.05 0.05

D Organophosphate Chlorpyrifos

Cyfluthrin 61585 68359-37-5 0.008 0.008 0.016 0.016 I Pyrethroid

–

lambda-Cyhalothrin 61595 91465-08-6 0.005 0.005 0.01 0.01 I Pyrethroid

–

Cypermethrin 61586 52315-07-8 0.01 0.01 0.02 0.02 I Pyrethroid

–

Desulfinylfipronil 62170 NA 0.006 0.006 0.012 0.012

D Phenyl pyrazole Fipronil

Desulfinylfipronil amide 62169 NA 0.015 0.015 0.029 0.029

D Phenyl pyrazole Fipronil

Diazinon 39572 333-41-5 0.003 0.003 0.005 0.005 I Organophosphate

–

Diazinon oxygen analog 61638 962-58-3 0.0021 0.0021 0.006 0.006

D Organophosphate Diazinon

Dicrotophos 38454 141-66-2 0.04 0.04 0.08 0.08 I Organothiophosphate

–

Dieldrin 39381 60-57-1 0.004 0.004 0.009 0.009 I Organochlorine

–

Dimethoate 82662 60-51-5 0.003 0.003 0.006 0.006 I Organothiophosphate

–

Disulfoton 82677 298-04-4 0.02 0.02 0.04 0.04 I Organophosphate

–

Disulfoton sulfone 61640 2497-06-5 0.0068 0.0068 0.014 0.0136

D Organophosphate Disulfoton

alpha-Endosulfan 34362 959-98-8 0.003 0.003 0.006 0.006 I Organochlorine

–

Endosulfan sulfate 61590 1031-07-8 0.011 0.007 0.022 0.014

D Organochlorine alpha-Endosulfan, betaEndosulfan

Ethion 82346 563-12-2 0.006 0.004 0.012 0.008 I Organothiophosphate

–

Ethion monoxon 61644 17356-42-2 0.011 0.011 0.021 0.021

D Organothiophosphate Ethion

Fipronil 62166 120068-37-3 0.02 0.009 0.04 0.018 I Phenyl pyrazole

–

Fipronil sulfide 62167 120067-83-6 0.006 0.006 0.013 0.013

D Phenyl pyrazole Fipronil

Table A4. Reporting limits, uses, and classes of currently used pesticides and degradates analyzed in filtered wastewater-treatment-plant effluent or stormwater runoff, Columbia 

River Basin, Washington and Oregon, 2009–10.—Continued

[Shading indicates a detection in wastewater-treatment-plant effluent; bold type indicates a detection in stormwater runoff in this study. CAS No.: Chemical Abstract Service Registry Number® is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs through CAS Client ServicesSM. Method detection limit and Reporting limit: Values are in micrograms per liter. 

Abbreviations: NA, not available; D, degradate; Def, defoilant; F, fumigant; Fun, fungicide; H, herbicide; I, insecticide; N, nematocide; –, not applicable]
Table A4 65

Analyte Parameter code CAS No.

Method detection limit Reporting limit

Use Class Parent compound February– September 

2009

October 2009–

June 2010

February–

September 

2009

October 2009–

June 2010

Insecticides and degradates—Continued

Fipronil sulfone 62168 120068-36-2 0.012 0.012 0.024 0.024 D Phenyl pyrazole Fipronil

Fonofos 04095 944-22-9 0.005 0.0022 0.01 0.0044 I Organophosphate –

Isofenphos 61594 25311-71-1 0.003 0.003 0.006 0.006 I Organothiophosphate –

Malaoxon 61652 1634-78-2 0.04 0.04 0.08 0.08 D Organophosphate Malathion

Malathion 39532 121-75-5 0.01 0.008 0.02 0.016 I Organophosphate –

Methidathion 61598 950-37-8 0.003 0.003 0.006 0.006 I Organothiophosphate –

Methyl paraoxon 61664 950-35-6 0.005 0.005 0.01 0.01 D Organophosphate Methyl parathion

Methyl parathion 82667 298-00-0 0.004 0.004 0.008 0.008 I Organophosphate –

cis-Permethrin 82687 61949-76-6 0.007 0.007 0.014 0.014 I Pyrethroid –

Phorate 82664 298-02-2 0.01 0.01 0.02 0.02 I Organophosphate –

Phorate oxon 61666 2600-69-3 0.013 0.013 0.027 0.027 D Organophosphate Phorate

Phosmet 61601 732-11-6 0.1 0.017 0.2 0.034 I Organothiophosphate –

Phosmet oxon 61668 3735-33-9 0.0079 0.0079 0.0511 0.0511 D Organothiophosphate Phosmet

Propargite 82685 2312-35-8 0.01 0.01 0.02 0.02 I Miscellaneous –

Tefluthrin 61606 79538-32-2 0.005 0.005 0.01 0.01 I Pyrethroid –

Terbufos 82675 13071-79-9 0.009 0.009 0.018 0.018 I Organophosphate –

Terbufos oxygen analog sulfone 61674 56070-15-6 0.022 0.022 0.045 0.045 D Organophosphate Terbufos

Other compounds

Dichlorvos 38775 62-73-7 0.01 0.01 0.02 0.02 F, D Organophosphate Naled

Ethoprop 82672 13194-48-4 0.008 0.008 0.016 0.016 N, I Organophosphate –

Fenamiphos 61591 22224-92-6 0.015 0.015 0.029 0.03 N Organothiophosphate –

Fenamiphos sulfone 61645 31972-44-8 0.027 0.027 0.053 0.053 D Organothiophosphate Fenamiphos

Fenamiphos sulfoxide 61646 31972-43-7 0.04 0.04 0.08 0.08 D Organothiophosphate Fenamiphos

1-Naphthol 49295 90-15-3 0.02 0.018 0.04 0.036 D Carbamate, 

Chloroacetamide

Carbaryl, Napropamide

Tribufos 61610 78-48-8 0.018 0.009 0.035 0.018 Def Organothiophosphate –

Table A4. Reporting limits, uses, and classes of currently used pesticides and degradates analyzed in filtered wastewater-treatment-plant effluent or stormwater runoff, Columbia 

River Basin, Washington and Oregon, 2009–10.—Continued

[Shading indicates a detection in wastewater-treatment-plant effluent; bold type indicates a detection in stormwater runoff in this study. CAS No.: Chemical Abstract Service Registry Number® is a Registered Trademark of the American Chemical Society. CAS recommends the verification of the CASRNs through CAS Client ServicesSM. Method detection limit and Reporting limit: Values are in micrograms per liter. 

Abbreviations: NA, not available; D, degradate; Def, defoilant; F, fumigant; Fun, fungicide; H, herbicide; I, insecticide; N, nematocide; –, not applicable]
66 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

Analyte Parameter

code

CAS

No.

Reporting limit (μg/L)

October 

2008– 

September 

2009

October 

2009–

September 

2010

Acenaphthene 34205 83-32-9 0.28 0.28

Acenaphthylene 34200 208-96-8 0.3 0.3

Anthracene 34220 120-12-7 0.39 0.39

Benzo[a]anthracene 34526 56-55-3 0.26 0.26

Benzo[a]pyrene 34247 50-32-8 0.33 0.33

Benzo[b]fluoranthene 34230 205-99-2 0.4 0.3

Benzo[ghi]perylene 34521 191-24-2 0.4 0.38

Benzo[k]fluoranthene 34242 207-08-9 0.4 0.3

4-Bromophenylphenylether 34636 101-55-3 0.36 0.24

Butylbenzyl phthalate 34292 85-68-7 1.8 1.8

bis(2-Chloroethoxy)methane 34278 111-91-1 0.2 0.24

bis(2-Chloroethyl)ether 34273 111-44-4 0.3 0.3

bis(2-Chloroisopropyl) ether 34283 108-60-1 0.38 0.14

4-Chloro-3-methylphenol 34452 59-50-7 0.55 0.55

2-Chloronaphthalene 34581 91-58-7 0.2 0.16

2-Chlorophenol 34586 95-57-8 0.42 0.26

4-Chlorophenyl phenyl ether 34641 7005-72-3 0.34 0.34

Chrysene 34320 218-01-9 0.33 0.33

Dibenz[ah]anthracene 34556 53-70-3 0.4 0.42

1,2-Dichlorobenzene 34536 95-50-1 0.2 0.2

1,3-Dichlorobenzene 34566 541-73-1 0.2 0.22

1,4-Dichlorobenzene 34571 106-46-7 0.2 0.22

3,3′-Dichlorobenzidine 34631 91-94-1 0.4 0.42

2,4-Dichlorophenol 34601 120-83-2 0.39 0.36

Diethyl phthalate 34336 84-66-2 0.61 0.61

Dimethyl phthalate 34341 131-11-3 0.4 0.36

2,4-Dimethylphenol 34606 105-67-9 0.8 0.8

4,6-Dinitro-2-methylphenol 34657 534-52-1 0.77 0.76

Analyte Parameter

code

CAS

No.

Reporting limit (μg/L)

October 

2008– 

September 

2009

October 

2009–

September 

2010

2,4-Dinitrophenol 34616 51-28-5 1.4 1.4

2,4-Dinitrotoluene 34611 121-14-2 0.6 0.56

2,6-Dinitrotoluene 34626 606-20-2 0.43 0.4

1,2-Diphenylhydrazine 82626 122-66-7 0.3 0.3

Di-n-butyl phthalate 39110 84-74-2 1 2

Di-n-octyl phthalate 34596 117-84-0 0.6 0.6

bis(2-Ethylhexyl) phthalate 39100 117-81-7 2 2

Fluoranthene 34376 206-44-0 0.3 0.3

Fluorene 34381 86-73-7 0.33 0.33

Hexachlorobenzene 39700 118-74-1 0.3 0.3

Hexachlorobutadiene 39702 87-68-3 0.2 0.24

Hexachlorocyclopentadiene 34386 77-47-4 0.4 0.5

Hexachloroethane 34396 67-72-1 0.2 0.24

Indeno[1,2,3-cd]pyrene 34403 193-39-5 0.4 0.38

Isophorone 34408 78-59-1 0.4 0.26

Naphthalene 34696 91-20-3 0.32 0.22

Nitrobenzene 34447 98-95-3 0.2 0.26

2-Nitrophenol 34591 88-75-5 0.4 0.4

4-Nitrophenol 34646 100-02-7 0.51 0.51

N-Nitrosodimethylamine 34438 62-75-9 0.2 0.24

N-Nitrosodi-n-propylamine 34428 621-64-7 0.4 0.4

N-Nitrosodiphenylamine 34433 86-30-6 0.4 0.28

Pentachlorophenol 39032 87-86-5 1.2 0.6

Phenanthrene 34461 85-01-8 0.32 0.32

Phenol 34694 108-95-2 0.44 0.28

Pyrene 34469 129-00-0 0.35 0.35

1,2,4-Trichlorobenzene 34551 120-82-1 0.2 0.26

2,4,6-Trichlorophenol 34621 88-06-2 0.6 0.34

Table A5. Reporting limits of polyaromatic hydrocarbons analyzed in unfiltered stormwater runoff, Columbia River Basin, Washington 

and Oregon, 2009–10.

[Bold type indicates a detection in stormwater runoff in this study. CAS No.: Chemical Abstract Service Registry Number® is a Registered Trademark of the 

American Chemical Society. CAS recommends the verification of the CASRNs through CAS Client ServicesSM. Abbreviation: μg/L, micrograms per liter]
Table A6 67

Table A6. Reporting limits and methods used for trace elements 

analyzed in stormwater runoff, Columbia River Basin, Washington 

and Oregon, 2009–10.

[Bold type indicates a detection in stormwater runoff in this study. CAS No.:

Chemical Abstract Service Registry Number® is a Registered Trademark of the 

American Chemical Society. CAS recommends the verification of the CASRNs 

through CAS Client ServicesSM. Abbreviation: μg/L, micrograms per liter]

Analyte Parameter

code

Method

No.

CAS

No.

Reporting limit (μg/L)

October 

2008–

September 

2009

October 

2009–

September 

2010

Unfiltered water

Arsenic 01002 PLM11 7440-38-2 0.20 0.18

Cadmium 01027 PLM47 7440-43-9 0.06 0.04

Chromium 01034 PLM11 7440-47-3 0.40 0.42

Copper 01042 PLM11 7440-50-8 4.0 1.4

Lead 01051 PLM48 7439-92-1 0.10 0.06

Mercury 02708 CV018 7439-97-6 0.01 0.01

Nickel 01067 PLM11 7440-02-0 0.20 0.36

Selenium 01147 PLM11 7782-49-2 0.12 0.10

Silver 01077 PLM48 7440-22-4 0.06 0.016

Zinc 01092 PLA15 7440-66-6 4.0 4.0

Filtered water

Arsenic 01000 PLM10 7440-38-2 0.06 0.044

Cadmium 01025 PLM43 7440-43-9 0.02 0.02

Chromium 01030 PLM10 7440-47-3 0.12 0.12

Copper 01040 PLM10 7440-50-8 1.0 1.0

Lead 01049 PLM43 7439-92-1 0.06 0.03

Mercury 02707 CV014 7439-97-6 0.01 0.01

Nickel 01065 PLM10 7440-02-0 0.12 0.12

Selenium 01145 PLM10 7782-49-2 0.06 0.04

Silver 01075 PLM43 7440-22-4 0.01 0.01

Zinc 01090 PLA11 7440-66-6 2.0 4.6
68 Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10 

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Morace— Contaminants in Wastewater-Treatment-Plant Effluent and Stormwater Runoff, Columbia River Basin, Washington and Oregon, 2008–10—Scientific Investigations Report 2012–5068