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Cover: View of Swamp Creek downstream (south) from the 175th Street bridge near Bothell Way. 

(Photograph taken by Sara Coughlin, King County Department of Natural Resources, 2002.)
Pesticides Detected in Urban Streams in 

King County, Washington, 1998–2003

By Lonna M. Frans

Prepared in cooperation with the 

King County Department of Natural Resources

Scientific Investigations Report 2004–5194

U.S. Department of the Interior

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

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

U.S. Geological Survey, Reston, Virginia: 2004

For sale by U.S. Geological Survey, Information Services

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

World Wide Web: http://www.usgs.gov

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply 

endorsement by the 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:

Frans, Lonna M., 2004, Pesticides detected in urban streams in King County, Washington, 1998–2003: U.S. Geological 

Survey Scientific Investigations Report 2004–5194, 19 p.
iii

Contents

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

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

Methods ................................................................................................... 3

Sample Collection and Processing ............................................................... 3

Laboratory Procedures ........................................................................... 3

Results of Quality–Control Assessment ......................................................... 6

Pesticide Detections .................................................................................... 7

Effect of Storms on Pesticide Detections ............................................................ 10

Potential Pesticide Sources ........................................................................... 12

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

References Cited .......................................................................................... 13

Figures

Figure 1. Map showing location of sites sampled for pesticides and pesticide transformation 

products on urban streams in King County, Washington, 1998–2003 .................. 2

Figure 2. Graph showing percentage of samples with detections of pesticides in urban 

streams in King County, Washington, 1998–2003 .......................................... 9

Figure 3. Graph showing number of compounds detected for each class of pesticides at 

sampling sites on urban streams in King County, Washington, 1998–2003 ............ 9

Figure 4. Graph showing percentage of each class of pesticides detected at sampling 

sites on urban streams in King County, Washington, 1998–2003 ........................ 10

Figure 5. Graphs showimg maximum concentrations of pesticides and pesticide 

transformation products detected during storms and during base flow at 

sampling sites on urban streams in King County, Washington, 1998–2003 ............ 11

Figure 6. Graph showinf percentage of samples with pesticide detections in urban 

streams in King County, Washington, during spring and autumn storms, 

1998–2003 ....................................................................................... 12

Tables

Table 1. Sites sampled for pesticides and pesticide transformation products in King 

County, Washington, 1998-2003. ............................................................ 3

Table 2. Analytes and laboratory reporting levels for pesticides analyzed at the U.S. 

Geological Survey National Water Quality Laboratory or the U.S. Geological 

Survey Organic Geochemistry Research Laboratory .................................... 4

Table 3. Analytes and quantitation limits for pesticides analyzed at the Washington 

State Department of Ecology Manchester Environmental Laboratory .................. 5

Table 4. Concentrations and precision data for replicate samples with detections ............ 7

Table 5. Pesticides and pesticide transformation products detected in water samples 

collected at sites on urban streams in King County, Washington, 1998–2003 ......... 8

Table 6. Concentrations of pesticides and pesticide transformation products detected in 

stream water samples during storms and during baseflow at sites on streams in 

King County, Washington, 1998–2003 ...................................................... 14
iv

Conversion Factors and Datum

Inch/Pound to SI

Multiply By To obtain

Length

mile (mi 1.609 kilometer

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

micrograms per liter (μg/L.

Datum

Horizontal coordinate information is referenced to the North American Datum of 1927 (NAD 27.
Abstract

The U.S. Geological Survey and the King County 

Department of Natural Resources collected water samples 

from 14 sites on urban streams in King County during storms 

and during base flow between 1998 and 2003. The samples 

were analyzed for the presence of 155 pesticides and pesticide 

transformation products. 

Thirty-nine of the compounds were detected at least 

once during the study: 20 herbicides, 9 insecticides, 2 

fungicides, 6 pesticide transformation products, and 2 other 

types of compounds. The most widespread compound was 

4-nitrophenol, which was detected at all 14 sampling sites. The 

most frequently detected compound was pentachlorophenol, 

a fungicide, which occurred in more than 80 percent of 

the samples. The most frequently detected herbicides were 

prometon, trichlopyr, 2,4-D, and MCPP, and the most 

frequently detected insecticides were diazinon and carbaryl. 

All of the most frequently detected herbicides and insecticides 

were sold for homeowner use over the timeframe of this study.

More compounds were detected during storms than 

during base flow, and were detected more frequently and 

typically at high concentrations during storms. Seven 

compounds were detected only during storms. Most of the 

compounds that were detected during storms occurred more 

frequently during spring storms than during autumn storms.

Introduction

A wide variety of pesticides are applied each year 

to urban and suburban residential areas in King County, 

Washington. In order to assess the occurrence and distribution 

of these pesticides and their transformation products, the U.S. 

Geological Survey (USGS) and the King County Department 

of Natural Resources collected water samples at 14 sites 

on streams in the Lake Washington drainage basin in King 

County between 1998 and 2003 (fig. 1 and table 1). The 

water samples were analyzed for 155 pesticides and pesticide 

transformation products (hereafter referred to as pesticides) at 

three laboratories using three different methods.

Twelve of the sampling sites were small streams that 

drain generally urban areas, and one site (site 14) was a small 

stream running out of an urban area with potential agricultural 

runoff sources. The last site (site 2, Rock Creek) was in a nonurban forested area and was used as a reference site. 

The purpose of this report is to describe the types and 

concentrations of pesticides detected at each sampling site, 

the effects of storms and base flow on the distribution and 

concentration of pesticides at the sites, and the potential 

sources of the pesticides present.

Pesticides Detected in Urban Streams in King County, 

Washington, 1998–2003

By Lonna M. Frans 
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Figure 1. Location of sites sampled for pesticides and pesticide transformation products on urban streams in King 

County, Washington, 1998–2003. 

2 Pesticides Detected in Urban Streams in King County, Washington, 1998–2003
Methods

Water samples for the pesticide analysis were collected at 

the sampling sites and processed at three laboratories between 

1998 and 2003. 

Sample Collection and Processing 

Samples were collected by either manual sampling or 

an automated sampler (autosampler). Manual samples were 

collected using a US DH-81 sampler, as described by Wilde 

and others (1999a), except at the irrigation return, where the 

sample bottle was dipped directly into the flow. The samplers 

can hold either a 1- or 3-liter Teflon® sample bottle, and all 

parts of the sampler coming into contact with sample water 

were made of Teflon®. Samples were collected using the 

equal-width-increment (EWI) method, in which a transect was 

established across the width of the creek. Water was collected 

at about 10 equally spaced intervals along the transect by 

lowering and raising the sampler vertically through the water 

column. The collected water from each interval then was 

composited into a glass carboy. Autosamplers were installed 

to sample runoff during the storms from 2000 to 2003 and 

were triggered during a rainstorm when the level of the creek 

rose. When the autosampler was triggered, the water sample 

was collected from a single point in the midpoint of the stream 

through a Teflon® tube into a glass carboy (Isco, Inc., 1992). 

Water in the streams was well mixed at the sampling point.

Except for the autosampler, all equipment used to 

collect and process samples was cleaned with a 0.2-percent 

nonphosphate detergent, rinsed with deionized water, 

rinsed with pesticide-grade methanol, air-dried, wrapped in 

aluminum foil, and stored in a dust-free environment prior 

to sample collection (Wilde and others, 1999b). All of the 

autosampler parts that contacted the sample were washed in 

detergent, soaked in sulfuric acid for 24 hours, rinsed with 

deionized water, and stored in plastic bags. All bottles used to 

collect stream water were rinsed thoroughly with the stream 

water before sample collection and processing.

The samples in the glass carboys were split using a 

Teflon® cone splitter into individual samples for analysis 

at the USGS National Water Quality Laboratory (NWQL) 

in Lakewood, Colorado, the USGS Organic Geochemistry 

Research Laboratory (OGRL) in Lawrence, Kansas (2002 and 

2003 samples only), and the Washington State Department 

of Ecology Manchester Environmental Laboratory in 

Manchester, Washington, (Wilde and others, 1999c). Samples 

were processed within 24 hours of collection. The equipment 

and procedures used to collect and process samples are 

described by Wilde and others (1999a, 1999c). Samples 

collected for analysis by the USGS laboratories were filtered 

through a 0.7-micrometer pore-size, baked glass-fiber filter 

into baked amber-glass bottles and shipped on ice within 24 

hours of filtration. Samples for analysis by the Manchester 

Environmental Laboratory were collected from the cone 

splitter in clear glass bottles, but were not filtered. They were 

stored on ice and transported to the laboratory within 24 hours 

of processing.

Laboratory Procedures

The samples were analyzed for 155 pesticides and 

pesticide transformation products (hereafter referred to as 

pesticides) by the three laboratories. At the NWQL, known 

quantities of surrogate compounds were added to each water 

sample and then passed through a solid-phase extraction (SPE) 

cartridge to extract pesticide compounds. The SPE cartridge 

was packed with porous silica coated with a carbon-18 organic 

phase. Pesticides retained on the SPE cartridges were eluted 

with a hexane-isopropanol mixture, which was analyzed for 

52 pesticides using gas chromatography/mass spectrometry 

(GC/MS) with selected ion monitoring (Zaugg and others, 

1995, and Madsen and others, 2003) (table 2). Fipronil and 

its transformation products were added to the analyte list in 

autumn 2002, so those compounds were analyzed for only in 

the final sample at Little Bear Creek, North Creek, and the 

irrigation return, as well as all samples from May, Kelsey, and 

Taylor Creeks. 

At the OGRL, the samples were derivatized (converted to 

another chemical compound for identification) with 9-fluorenylmethylchloroformate, passed through an SPE cartridge, and 

analyzed for three pesticides (table 2) using high-performance 

liquid chromatography/mass spectrometry (HPLC/MS) (Lee 

and others, 2002).

Methods 3

Site No. 

(see fig. 1 for 

location)

USGS station No. Site name

1 12113499 Taylor Creek

2 12117695 Rock Creek

3 12119600 May Creek

4 12119990 Kelsey Creek

5 12120480 Juanita Creek

6 12121600 Issaquah Creek

7 12121750 Lewis Creek

8 12124500 Bear Creek

9 12125500 Little Bear Creek

10 12126200 North Creek

11 12127000 Swamp Creek

12 12127290 Lyon Creek at 178th

13 12127300 Lyon Creek at Lake Forest Park

14 474243122083001 Unnamed Creek @ 124th

Table 1. Sites sampled for pesticides and pesticide 

transformation products in King County, Washington, 1998-2003.
At the Manchester Environmental Laboratory, pesticides 

present in the whole-water samples were extracted using 

methylene chloride and analyzed for 141 targeted pesticides 

(table 3) using U.S. Environmental Protection Agency 

Method 8085, which uses capillary-column GC analysis with 

an atomic emission detector (AED) and ion-trap GC/MS 

confirmation (Norman Olson, Manchester Environmental 

Laboratory, written commun., 1999). This method also 

permitted detection of several non-target compounds on 

certain occasions. During 2001, a portion of the water from 

Bear and Issaquah Creeks was filtered at the laboratory to 

provide a comparison of filtered and unfiltered analyses. Some 

pesticides were analyzed by both NWQL and Manchester 

Environmental Laboratory.

4 Pesticides Detected in Urban Streams in King County, Washington, 1998–2003

Pesticide target 

analyte

Trade or common 

name(s)

Type of 

pesticide

Chemical 

Abstracts 

Service 

registry No.

Laboratory 

reporting 

level 

(μg/L)

National Water Quality Laboratory

Acetochlor Acenit, Sacenid H 34256-82-1 0.006

Alachlor Lasso H 15972-60-8 .005

Atrazine AAtrex H 1912-24-9 .007

Azinphos-methyl1 Guthion I 86-50-0 .050

Benfluralin Balan, Benefin H 1861-40-1 .010

Butylate Sutan +, Genate 

Plus

H 2008-41-5 .004

Carbaryl1 Sevin, Savit I 63-25-2 .041

Carbofuran1 Furadan I 1563-66-2 .020

Chlorpyrifos Lorsban I 2921-88-2 .005

Cyanazine Bladex H 21725-46-2 .018

DCPA Dacthal H 1861-32-1 .003

4,4’-DDE – T 72-55-9 .003

Desethylatrazine1 – T 6190-65-4 .006

Desulfinylfipronil2 – T – .012

Desulfinylfipronilamide2– T – .029

Diazinon Several I 333-41-5 .005

Dieldrin Panoram D-31 I 60-57-1 .009

2,6-Diethylanaline – T 579-66-8 .006

Disulfoton Di-Syston I 298-04-4 .021

EPTC Eptam, Eradicane H 759-94-4 .004

Ethalfluralin Sonalan, Curbit EC H 55283-68-6 .009

Ethoprophos Mocap I 13194-48-4 .005

Fipronil2 Regent I 120068-37-3 .016

Fipronil sulfide2 – T 120067-83-6 .013

Fipronil sulfone2 – T 120068-36-2 .024

Fonofos Dyfonate I 944-22-9 .003

alpha-HCH – I 319-84-6 .005

gamma-HCH Lindane I 58-89-9 .004

Pesticide target 

analyte

Trade or common 

name(s)

Type of 

pesticide

Chemical 

Abstracts 

Service 

registry No.

Laboratory 

reporting 

level 

(μg/L)

National Water Quality Laboratory

Linuron Lorox, Linex H 330-55-2 0.035

Malathion Several I 121-75-5 .027

Methyl parathion Penncap-M I 298-00-0 .015

Metolachlor Dual, Pennant H 51218-45-2 .013

Metribuzin Lexone, Sencor H 21087-64-9 .006

Molinate Ordram H 2212-67-1 .003

Napropamide Devrinol H 15299-99-7 .007

Parathion Several I 56-38-2 .010

Pebulate Tillam H 1114-71-2 .004

Pendimethalin Prowl, Stomp H 40487-42-1 .022

cis-Permethrin Ambush, Pounce I 54774-45-7 .006

Phorate Thimet, Rampart I 298-02-2 .011

Prometon Pramitol H 1610-18-0 .005

Propyzamide Kerb H 23950-58-5 .004

Propachlor Ramrod H 1918-16-7 .025

Propanil Stampede H 709-98-8 .011

Propargite Comite, Omite I 2312-35-8 .023

Simazine Aquazine, Princep H 122-34-9 .005

Tebuthiuron Spike H 34014-18-1 .016

Terbacil1 Sinbar H 5902-51-2 .034

Terbufos Counter I 13071-79-9 .017

Thiobencarb Bolero H 28249-77-6 .010

Triallate Far-Go H 2303-17-5 .002

Trifluralin Treflan, Trilin H 1582-09-8 .009

Organic Geochemistry Research Laboratory

Aminomethylphosphonic acid– T 1066-51-9 0.1

Glufosinate Finale, Liberty H 77182-82-2 .1

Glyphosate Roundup H 1071-83-6 .1

Table 2. Analytes and laboratory reporting levels for pesticides analyzed at the U.S. Geological Survey National Water Quality 

Laboratory or the U.S. Geological Survey Organic Geochemistry Research Laboratory.

[Trade or common name(s): Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by 

the U.S. Geological Survey. Type of pesticide: H, herbicide; I, insecticide; T, transformation product. –, no trade or common name or registry number; μg/L, 

microgram per liter]

1

Concentrations for these pesticides are qualitatively identified and reported with a J code (estimated value). J codes are used to signify estimated values 

for all detections that are less than the method detection limit, greater than the highest calibration standard, or otherwise less reliable than average because of 

sample-specific or compound-specific considerations. All J-coded data are considered to be reliable detections, but with greater than average uncertainty in 

quantification.

2

These compounds were added to the method in autumn 2002.
Pesticide target 

analyte

Trade or 

common 

name(s)

Type of 

pesticide

Chemical 

Abstracts 

Service 

registry No.

Quantitation 

limit

(μg/L)

Acifluorfen-sodium Blazer H 62476-59-9 0.17

Alachlor Lasso H 15972-60-8 .26

Aldrin – I 309-00-2 .035

Ametryn Evik, Gesapax H 834-12-8 .071

Atraton – H 1610-17-9 .21

Atrazine AAtrex H 1912-24-9 .071

Azinphos-methyl Guthion I 86-50-0 .12

Azinphos ethyl Gusathion A I 2642-71-9 .12

Benfluralin Balan, Benefin H 1861-40-1 .11

Bentazon Basagran H 25057-89-0 .063

Bromacil Hyvar, Woprovar H 314-40-9 .28

Bromoxynil Bromanil, Emblem H 1689-84-5 .042

Butachlor Butanox, Machete H 23184-66-9 .25

2-Butoxy-ethanol 

phosphate1

– O 78-51-3 –

Butylate Sutan +, 

Genate Plus

H 2008-41-5 .14

Caffeine1 – O 58-08-2 –

Captafol Difolatan, Foltaf F 2425-06-1 .21

Captan Orthocide F 133-06-2 .14

Carbophenothion Trithion I 786-19-6 .80

Carboxin Vitavax F 5234-68-4 .78

cis-Chlordane Terminator I 5103-71-9 .035

trans-Chlordane Terminator I 5103-74-2 .035

alpha-Chlordene – I 56534-02-2 .043

gamma-Chlordene – I 56641-38-4 .035

Chlorothalonil Daconil, Bravo F 1897-45-6 .17

Chlorpropham Taterpex, 

Sprout Nip

H 101-21-3 .28

Chlorpyrifos Lorsban I 2921-88-2 .055

Coumaphos Agridip I 56-72-4 .090

Cyanazine Bladex H 21725-46-2 .11

Cycloate Sabet H 1134-23-2 .14

2,4-D Weed-B-Gon, 

Weedone

H 94-75-7 .042

2,4-DB Venceweed, 

Butoxone

H 94-82-6 .050

DCPA Dacthal H 1861-32-1 .033

2,4’-DDD TDE I 53-19-0 .035

2,4’-DDE – T 3424-82-6 .035

4,4’-DDD TDE I 72-54-8 .035

4,4’-DDE – T 72-55-9 .035

DDMU – T 1022-22-6 .035

2,4’-DDT DDT I 789-02-6 .035

4,4’-DDT DDT I 50-29-3 .035

Demeton-O – I 298-03-3 .055

Demeton-S – I 126-75-0 .060

Di-allate – H 2303-16-4 .27

Diazinon Several I 333-41-5 .06

Dicamba Banvel H 1918-00-9 .042

Dichlobenil Barrier, Casoron H 1194-65-6 .16

2,6-Dichlorobenzamide1– T 2008-58-4 –

3,5-Dichlorobenzoic 

Acid

– H 51-36-5 .042

Dichlorprop 2,4-DP, Seritox 50 H 120-36-5 .046

Dichlorvos DDVP I 62-73-7 .060

Dicofol Kelthane I 115-32-2 .17

Diclofop-methyl Hoelon H 51338-27-3 .063

Pesticide target 

analyte

Trade or 

common 

name(s)

Type of 

pesticide

Chemical 

Abstracts 

Service 

registry No.

Quantitation 

limit

(μg/L)

Dieldrin Panoram D-31 I 60-57-1 0.035

Dimethoate Trounce, Roxion I 60-51-5 .060

Dinoseb DNBP H 88-85-7 .063

Dioxathion – I 78-34-2 .12

Diphenamid – H 957-51-7 .21

Disulfoton Di-Syston I 298-04-4 .045

Diuron Karmex, Direx H 330-54-1 .48

Endosulfan I Several I 959-98-8 .035

Endosulfan II Several I 33213-65-9 .035

Endosulfan sulfate – T 1031-07-8 .035

Endrin Hexadrin I 72-20-8 .035

Endrin aldehyde – T 7421-93-4 .035

Endrin ketone – T 53494-70-5 .035

EPN – I 2104-64-5 .075

EPTC Eptam, Eradicane H 759-94-4 .14

Ethalfluralin Sonalan, Curbit EC H 55283-68-6 .11

Ethion Ethiosul I 563-12-2 .055

Ethofumesate1 Nortron, Tramat H 26225-79-6 –

Ethoprophos Mocap I 13194-48-4 .060

Fenamiphos Nemacur I 22224-92-6 .12

Fenarimol Rubigan F 60168-88-9 .21

Fenitrothion Fenitox, Rothion I 122-14-5 .055

Fensulfothion – I 115-90-2 .075

Fenthion Baytex I 55-38-9 .055

Fluridone Sonar H 59756-60-4 .13

Fonofos – I 944-22-9 .045

alpha-HCH – T 319-84-6 .035

beta-HCH – I 319-85-7 .035

delta-HCH – I 319-86-8 .035

gamma-HCH Lindane I 58-89-9 .035

Heptachlor Fennotox I 76-44-8 .035

Heptachlor Epoxide – T 1024-57-3 .035

Hexazinone Velpar H 51235-04-2 .11

Ioxynil Certrol H H 1689-83-4 .042

Malathion several I 121-75-5 .060

MCPA Metaxon, Kilsem H 94-74-6 .083

MCPP Mecoprop H 93-65-2 .083

Merphos (1 & 2) Folex H 150-50-5 .12

Metalaxyl Apron F 57837-19-1 .48

Methoxychlor Marlate I 72-43-5 .035

Methyl chlorpyrifos Reldan I 5598-13-0 .050

Methyl paraoxon – T 950-35-6 .15

Methyl parathion Penncap-M I 298-00-0 .055

Metolachlor Dual, Pennant H 51218-45-2 .28

Metribuzin Lexone, Sencor H 21087-64-9 .071

Mevinphos Phosdrin I 7786-34-7 .075

MGK264 – I 113-48-4 .50

Mirex – I 2385-85-5 .035

Molinate Ordram H 2212-67-1 .14

Napropamide Devrinol H 15299-99-7 .21

4-Nitrophenol – T 100-02-7 .073

cis-Nonachlor – I 5103-73-1 .035

trans-Nonachlor – I 39765-80-5 .035

Norflurazon Evital, Solicam H 27314-13-2 .14

Oxadiazon1 Ronstar, Order H 19666-30-9 –

Oxychlordane – T 27304-13-8 .035

Oxyfluorfen Goal H 42874-03-3 .28

Parathion several I 56-38-2 .06

Pebulate Tillam H 1114-71-2 .14

Pendimethalin Prowl, Stomp H 40487-42-1 .11

Pentachlorophenol PCP, Penta F 87-86-5 .021

Table 3. Analytes and quantitation limits for pesticides analyzed at the Washington State Department of Ecology Manchester 

Environmental Laboratory.

[Trade or common name(s): Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by 

the U.S. Geological Survey. Quantitation limit: Limits are approximate and often are different for each sample; these values are representative of a typical 

sample. Type of Pesticide: F, fungicide; H, herbicide; I, insecticide; T, transformation product; O, other. μg/L, microgram per liter; –, none available]

Methods 5
Results of Quality–Control Assessment

During the study, one equipment blank, five field 

blanks, and one replicate were analyzed in conjunction with 

environmental samples to assess bias and analytical variability. 

Field and equipment blanks were prepared with organic-grade 

water obtained from the NWQL. The blanks and replicate 

were subjected to all the same sample handling and processing 

as the environmental samples.

Pesticides were not detected in the field or equipment 

blanks. Concentration differences in the set of replicate 

samples ranged from 0.88 to 4.0 percent, as measured by 

relative percentage of difference, for samples analyzed by 

Pesticide target 

analyte

Trade or 

common 

name(s)

Type of 

pesticide

Chemical 

Abstracts 

Service 

registry No.

Quantitation 

limit

(μg/L)

Phorate Thimet, Rampart I 298-02-2 0.055

Phosmet Imidan I 732-11-6 .080

Phosphamidon Dixon I 13171-21-6 .18

Picloram Tordon H 1918-02-1 .042

Profluralin – H 26399-36-0 .17

Prometon Pramitol H 1610-18-0 .071

Prometryn Caparol, Gesagard H 7287-19-6 .071

Propyzamide Kerb H 23950-58-5 .28

Propachlor Ramrod H 1918-16-7 .17

Propazine Prozinex H 139-40-2 .071

Propetamphos Safrotin I 31218-83-4 .15

Ronnel Fenclorphos I 299-84-3 .055

Simazine Gesatop, Princep H 122-34-9 .072

Sulfotep Bladafum I 3689-24-5 .045

Sulprofos Bolstar I 35400-43-2 .055

2,4,5-T – H 93-76-5 .033

2,4,5-TB – H 93-80-1 .038

2,4,5-TP Silvex H 93-72-1 .033

Tebuthiuron Spike H 34014-18-1 .11

Table 3. Analytes and quantitation limits for pesticides analyzed at the Washington State Department of Ecology Manchester 

Environmental Laboratory.—Continued

[Trade or common name(s): Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by 

the U.S. Geological Survey. Quantitation limit: Limits are approximate and often are different for each sample; these values are representative of a typical 

sample. Type of Pesticide: F, fungicide; H, herbicide; I, insecticide; T, transformation product; O, other. μg/L, microgram per liter; –, none available]

1

Non-target analyte.

Pesticide target 

analyte

Trade or 

common 

name(s)

Type of 

pesticide

Chemical 

Abstracts 

Service 

registry No.

Quantitation 

limit

(μg/L)

Temephos Abate I 3383-96-8 0.70

Terbacil Sinbar H 5902-51-2 .21

Terbutryn Ternit H 886-50-0 .071

2,3,4,5-TetrachlorophenolDowicide 6 F 4901-51-3 .023

2,3,4,6-TetrachlorophenolDowicide 6 F 58-90-2 .023

Tetrachlorvinphos Gardona I 961-11-5 .15

Triadimefon Bayleton F 43121-43-3 .18

Triallate Far-Go H 2303-17-5 .18

Tribufos DEF H 78-48-8 .11

2,4,5-

Trichlorophenol

Dowicide 2 F 95-95-4 .025

2,4,6-

Trichlorophenol

Dowicide 2S F 88-06-2 .025

Triclopyr Garlon, Grazon H 55335-06-3 .035

Trifluralin Treflan, Trilin H 1582-09-8 .11

Vernolate – H 1929-77-7 .14

the NWQL and between 0.0 and 47.8 percent for samples 

analyzed by the Manchester Laboratory (table 4). The 

percentage of differences seem high for certain compounds, 

but the concentrations are very low, so even small differences 

in detectable concentrations can lead to large percentage of 

differences. Modifications were not made to the data set on the 

basis of these results. 

Quality-control procedures for the NWQL and 

Manchester Environmental Laboratory included the use 

of laboratory reagent blanks, spikes, surrogates, internal 

standards, and calibration as described by Huntamer and 

others (1992) and by Pritt and Raese (1995).

6 Pesticides Detected in Urban Streams in King County, Washington, 1998–2003
Pesticide Detections

Thirty-nine pesticides and pesticide transformation 

products were detected in water samples from the urban 

streams (table 5) (table 6, at back of report). Of the 39 

analytes detected, 20 were herbicides, 9 were insecticides, 

2 were fungicides, 6 were pesticide transformation products 

(4-nitrophenol is a transformation product of methyl parathion, 

2,6-dichlorobenzamide is a transformation product of 

Pesticide

Concentration in 

replicates 

(μg/L)

Relative percentage of 

difference

U.S. Geological Survey National Water Quality Laboratory analyses

Simazine 1.03

1.00

2.9

Prometon .114

.113

.88

Diazinon .194

.202

4.0

Carbaryl .121J

.118J

2.5

Washington Department of Ecology

Manchester Environmental Laboratory analyses

2,4-D 0.34

.36

5.7

4-Nitrophenol .1J

.065J

42.4

2,6-Dichlorobenzamide .086J

.14J

47.8

Diazinon .16

.11

37.0

Dicamba .027J

.02J

29.8

Dichlobenil .24

.18

28.6

Dichlorprop .032J

.032J

.0

MCPP .57

.54

5.4

Pentachlorophenol .1

.1

.0

Simazine .25

.17

38.1

Trichlopyr .18

.18

.0

Table 4. Concentrations and precision data for replicate samples 

with detections.

[Relative percentage of difference: Calculated as the difference between the 

two concentrations divided by the mean. J, estimated. μg/L, microgram per 

liter]

diclobenil, aminomethylphosphonic acid is a transformation 

product of glyphosate, desethylatrazine is a transformation 

product of atrazine, 4,4’-DDE is a transformation product of 

4,4’-DDT, and desulfinylfipronil amide is a transformation 

product of fipronil), and 2 were other types of compounds 

(caffeine and 2-butoxy-ethanol phosphate). However, not all 

compounds that were detected (table 5) were analyzed for in 

all samples because of changes in the analytical target lists 

(the addition of glyphosate, fipronil, and their transformation 

products) or because some of the detected compounds were 

non-target analytes. Therefore, for the remainder of this report, 

only those compounds that were analyzed for at all sites are 

presented in comparisons of detections between sites and the 

rates of compound detections. Additionally, the filtered and 

unfiltered results are combined, so a particular compound was 

counted as only one detection if it was detected in both the 

filtered and unfiltered samples.

The most widespread compound was 4-nitrophenol, 

which was detected at all sampling sites (table 5), but was 

detected in less than one-half the samples collected (fig. 2). 

The fungicide pentachlorophenol was the most frequently 

detected compound, and was detected in more than 80 

percent of the samples and at all sites except at the forested 

Rock Creek reference site (site 2). The herbicides prometon, 

trichlopyr, 2,4-D, and MCPP were present in more than 70 

percent of the samples collected and also were the most 

widespread herbicides, as they were detected at all sites 

except Rock Creek. Diazinon and carbaryl were the most 

widespread insecticides and were detected in 12 and 10 of 

the streams, respectively. They also were the most frequently 

detected insecticides, present in more than 60 and 30 percent 

of samples, respectively.

The largest number of compounds at detectable 

concentrations, 25, was in samples from Juanita Creek (site 5), 

followed by 22 in samples from the Unnamed Creek (site 14) 

and 21 in samples from Lyon Creek at 178th (site 12). Only 

two compounds were detected at the Rock Creek reference site 

(fig. 3). One or two fungicides and transformation products 

were detected at all streams except Rock Creek, where 

fungicides were not detected. Two to three insecticides were 

detected at most sites; however, five or more insecticides 

were detected in Juanita Creek, Lyon Creek at 178th, and the 

Unnamed Creek. Insecticides were not detected in Taylor 

(site 1) and Rock Creeks. Of the classes of compounds 

analyzed, the detections of herbicides varied the most among 

sites, ranging from one at Rock Creek to 15 at Juanita Creek. 

Between 6 and 12 herbicides were detected at most sites. 

Herbicides typically make up more than 60 percent of the 

compounds detected in each stream (fig. 4). 

Pesticide Detections 7
Table 5. Pesticides and pesticide transformation products detected in water samples collected at sites on urban streams in King 

County, Washington, 1998–2003.

[Sample site: na, not analyzed; ×, detected; –, not detected]

8 Pesticides Detected in Urban Streams in King County, Washington, 1998–2003

Pesticide

Sample site

Unnamed 

Creek

(site 14)

Juanita 

Creek

(site 5)

Little 

Bear 

Creek

(site 9)

Lyon 

Creek at 

178th

(site 12)

Lyon Creek at 

Lake Forest 

Park

(site 13)

North 

Creek

(site 10)

Lewis 

Creek

(site 7)

Kelsey 

Creek

(site 4)

Bear 

Creek

(site 8)

Issaquah 

Creek

(site 6)

Swamp 

Creek

(site 11)

May 

Creek

(site 3)

Taylor 

Creek

(site 1)

Rock 

Creek

(site 2)

4-Nitrophenol × × × × × × × × × × × × × ×

2,4-D × × × × × × × × × × × × × –

MCPP × × × × × × × × × × × × × –

Pentachlorophenol × × × × × × × × × × × × × –

Prometon × × × × × × × × × × × × × –

Trichlopyr × × × × × × × × × × × × × –

Diazinon × × × × × × × × × × × × – –

Dicamba × × × × × × × × – – – × × ×

Dichlobenil × × × × × × × × × × × – – –

Atrazine × × × × × × × – × × × – – –

Carbaryl × × × × × × – × × × – × – –

MCPA × × × × × – × × – × × – × –

Simazine × × × × × × × – × – × – – –

Malathion × × × × – × × – × – × – – –

2,6-Dichlorobenzamide × × × × na × × na × na na na na na

Diuron × × × × – – – – × × – – – –

Glyphosate × na × na na × na × na na na × × na

Chlorpyrifos × × – × × – × – – – – – – –

Metolachlor × × – – – – – × – – – × × –

Trifluralin × × – – × – – × – × – – – –

Desethylatrazine – – × – × – × – × – – – – –

Dichlorprop × × × × – – – – – – – – – –

Tebuthiuron × – × – × × – – – – – – – –

Aminomethylphosphonic acid × – × na na – na × na na na na na na

Bromacil – × × – × – – – – – – – – –

Caffeine × na × na na × na na na na na na na na

4,4’-DDD – × – × – – – – – – – – – –

4,4’-DDE – × – × – – – – – – – – – –

4,4’-DDT – × – × – – – – – – – – – –

EPTC – × – – – – × – – – – – – –

Napropamide – – × × – – – – – – – – – –

2-butoxy-ethanol phosphate na na na na na na na na na × na na na na

Carbofuran na na na na na na na – – – – – – –

Desulfinylfipronil amide na na na na na na na × na na na – – na

Ethofumesate × na na na na na na na na na na na na na

Fipronil na na na na na na na × na na na na na na

gamma-HCH – × – – – – – – – – – – – –

Metalaxyl × – – – – – – – – – – – – –

Oxadiazon × na na na na na na na na na na na na na
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Figure 2. Percentage of samples with detections of pesticides in urban streams in King County, Washington, 1998–2003.

Figure 3. Number of compounds detected for each class of pesticides at sampling sites on urban streams in King 

County, Washington, 1998–2003.

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Pesticide Detections 9
Effect of Storms on Pesticide 

Detections

More compounds were detected during storms than 

during base flow, and they were detected more frequently 

and typically at high concentrations (fig. 5). Seven of the 

compounds were detected only during storms and two 

were detected only during base flow. All other compounds 

were detected under both conditions. For most compounds, 

the percentage of samples with detections also was higher 

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Figure 4. Percentage of each class of pesticides detected at sampling sites on urban streams in King County, Washington, 

1998–2003.

during storms than during base flow. This is likely due to the 

increased flushing of the pesticides into the streams during 

storm events.

Eighteen of 28 compounds that were detected during 

storms occurred more frequently during spring storms than 

during autumn storms (fig. 6), and six of the compounds 

were not detected during autumn storms at all. This pattern 

of detection likely reflects the timing of pesticide application, 

because most pesticides are applied more often in the spring as 

homeowners begin working in their yards. 

10 Pesticides Detected in Urban Streams in King County, Washington, 1998–2003
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Figure 5. Maximum concentrations of pesticides and pesticide transformation products detected during storms and during base 

flow at sampling sites on urban streams in King County, Washington, 1998–2003.

Effect of Storms on Pesticide Detections 11
Potential Pesticide Sources

Residential use of pesticides is a possible major source 

for the most frequently detected compounds in the urban 

streams. Homeowners typically use pesticides for lawn and 

shrub care and for insect control around their property. For 

example, dichlobenil is a commonly used herbicide for weed 

control around woody shrubs and trees, and the popular 

insecticide diazinon is used to control ants, aphids, beetles, 

and other insects. Six of the seven most frequently detected 

pesticides (2,4-D, diazinon, dichlobenil, MCPP, prometon, 

and triclopyr) are currently sold for residential use or, in the 

case of diazinon, were just recently banned (Voss and Embrey, 

2000, and Phillip Dickey, Washington Toxics Coalition, 

written commun., 2004). The other most frequently detected 

pesticide, pentachlorophenol, likely does not originate from 

residential application. Pentachlorophenol is a common 

wood preservative that is used in pressure treatment of wood 

for uses such as utility poles and railroad ties. Several other 

pesticides that were detected (carbaryl, dicamba, glyphosate, 

malathion, MCPA, EPTC) also are sold in King County home 

and garden stores, and thus are available for residential use 

(Voss and Embrey, 2000, and Phillip Dickey, Washington 

Toxics Coalition, written commun., 2004). Although their 

sale is now banned for homeowner use, chlorpyrifos, which 

was detected at five sites, was available for retail sale until 

2001 and diazinon was available until 2003. Carbaryl sales 

increased substantially in 2002 as a replacement insecticide 

for chlorpyrifos and diazinon (Phillip Dickey, Washington 

Toxics Coalition, written commun., 2004). As a result of the 

phase out of chlorpyrifos and diazinon, their rates of detection 

likely will decrease in the future as homeowners use up any 

remaining stock that they have.

It is difficult to distinguish which of the pesticides 

detected in Unnamed Creek samples (site 14) are the result 

of urban application and which are the result of agricultural 

application because the irrigation-return water contains 

both urban and agricultural sources of water. The turf farm 

withdraws water from the Sammamish River for irrigation 

use and returns the water through a small stream that runs out 

of an urban area and then feeds into a ditch. However, of the 

four compounds detected only in the Unnamed Creek sample 

(ethofumesate, oxadiazon, carbofuran, and metalaxyl), none 

of them has recorded retail sales in King County and they are 

most often associated with agricultural applications. 

Figure 6. Percentage of samples with pesticide detections in urban streams in King County, Washington, during spring and autumn 

storms, 1998–2003.

12 Pesticides Detected in Urban Streams in King County, Washington, 1998–2003

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Summary

The U.S. Geological Survey and the King County 

Department of Natural Resources assessed the occurrence and 

distribution in urban streams in King County, Washington, 

of pesticides applied in urban and suburban residential areas. 

Water samples collected between 1998 and 2003 from 13 sites 

on urban streams and 1 reference site on a stream in a forested 

area were analyzed for the presence of 155 pesticides and 

pesticide transformation products during storms and during 

base flow. 

Samples were collected by either manual sampling or an 

automated sampler and were analyzed at the U.S. Geological 

Survey’s National Water Quality Laboratory and Organic 

Geochemistry Research Laboratory and the Washington State 

Department of Ecology Manchester Environmental 

Laboratory. 

Of the 155 compounds analyzed for, 39 were detected 

at least once during the study. Twenty of the compounds 

were herbicides, nine were insecticides, two were fungicides, 

six were transformation products, and two were other types 

of compounds. Only 4-nitrophenol was detected at all 14 

sampling sites. Pentachlorophenol, a fungicide, was the 

most frequently detected compound, occurring in more than 

80 percent of the samples. The most frequently detected 

herbicides were prometon, trichlopyr, 2,4-D, and MCPP, and 

the most frequently detected insecticides were diazinon and 

carbaryl. All of the most frequently detected herbicides and 

insecticides were sold for homeowner use over the timeframe 

of this study.

More compounds were detected during storms than 

during base flow, and seven compounds were detected only 

during storm events. Compounds also were detected more 

frequently and typically at high concentrations during storms. 

Most of the compounds that were detected during storms 

occurred more frequently during spring storms than during 

autumn storms.

Residential use of pesticides by homeowners is a possible 

major source for the most frequently detected compounds in 

the urban streams. Four compounds that were detected only 

in samples from the site on an irrigation return are most often 

associated with agricultural applications rather than residential 

use.

References Cited

Huntamer, D., Carrell, B., Olson, N., and Solberg, K., 1992, 

Washington State pesticide monitoring project, final 

laboratory report: Manchester, WA, Washington State 

Department of Ecology, Environmental Investigations and 

Laboratory Services Programs, Manchester Environmental 

Laboratory, 23 p.

Isco, Inc., 1992, 3700 portable sampler instruction manual, 

Revision D: Lincoln, Nebr., Isco, Inc., variously paged.

Lee, E.A., Strahan, A.P., and Thurman, E.M., 2002, Methods 

of analysis by the U.S. Geological Survey Organic 

Geochemistry Research Group—Determination of 

glyphosate, aminomethylphosphonic acid, and glufosinate 

in water using online solid-phase extraction and highperformance liquid chromatography/mass spectrometry: 

U.S. Geological Survey Open-File Report 01-454, 13 p.

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

Methods of analysis by the U.S. Geological Survey National 

Water Quality Laboratory—A method supplement for 

the determination of fipronil and degradates in water by 

gas chromatography/mass spectrometry: U.S. Geological 

Survey Open-File Report 02-462, 11 p.

Pritt, J.W., and Raese, J.W., 1995, Quality assurance/quality 

control manual, National Water Quality Laboratory: U.S. 

Geological Survey Open-File Report 95-443, 35 p.

Voss, F.D., and Embrey, S.S., 2000, Pesticides detected in 

urban streams during rainstorms in King and Snohomish 

Counties, Washington, 1998: U.S. Geological Survey 

Water-Resources Investigations Report 00-4098, 22 p.

Wilde, F.D., Radtke, D.B., Gibs, J., and Iwatsubo, R.T., 

eds., 1999a, Collection of water samples, in National 

field manual for the collection of water-quality data: 

U.S. Geological Survey Techniques of Water-Resources 

Investigations Book 9, chapter A4, 103 p.

Wilde, F.D., Radtke, D.B., Gibs, J., and Iwatsubo, R.T., eds., 

1999b, Cleaning of equipment for water sampling, in

National field manual for the collection of water-quality 

data: U.S. Geological Survey Techniques of WaterResources Investigations Book 9, chapter A3, 65 p.

Wilde, F.D., Radtke, D.B., Gibs, J., and Iwatsubo, R.T., 

eds., 1999c, Processing of water samples, in National 

field manual for the collection of water-quality data: 

U.S. Geological Survey Techniques of Water-Resources 

Investigations Book 9, chapter A5, 128 p.

Zaugg, S.D., Sandstrom, M.W., Smith, S.G., and Fehlberg, 

K.M., 1995, Methods of analysis by the U.S. Geological 

Survey National Water Quality Laboratory—Determination 

of pesticides in water by C-18 solid-phase extraction and 

capillary-column gas chromatography/mass spectrometry 

with selected-ion monitoring: U.S. Geological Survey 

Open-File Report 95-181, 49 p.

References Cited 13
Bear Creek (site 8)

Stream 

condition Date Collection method

2,4-D, 2,6-Dichlorobenzamide, 

unfiltered

4-Nitrophenol Atrazine, 

filtered

Carbaryl, 

filtered filtered unfiltered filtered unfiltered

Storm 05-14-01 Auto sampler 0.083J 0.076J 0.036J 0.054J 0.0045NJ 0.003J 0.081J

Storm 10-08-01 Auto sampler <.24 .031J – <.18 .14J <.007 <.041

Base flow 06-18-01 DH-81 .14J .15J – .051J .016J .004J <.041

Base flow 09-17-01 DH-81 <.21 .045J – .046J <.31 <.007 <.041

Stream 

condition Date Collection method

Desethylatrazine, 

filtered

Diazinon Dichlobenil, 

filtered

Diuron, 

filtered

Malathion, 

filtered 

MCPP

filtered unfiltered filtered unfitered

Storm 05-14-01 Auto sampler 0.002J 0.008 0.012J <0.057 0.011J <0.027 0.055J 0.065J

Storm 10-08-01 Auto sampler <.006 .005J .014J .021J <.20 .007J <.49 <.51

Base flow 06-18-01 DH-81 .002J <.005 <.018 .0079J .037NJ <.027 .028J .023J

Base flow 09-17-01 DH-81 <.006 <.005 <.016 <.052 <.16 <.027 <.42 <.36

Stream 

condition Date Collection method

Pentachlorophenol Prometon Simazine Trichlopyr

filtered unfiltered filtered unfiltered filtered unfiltered filtered unfiltered

Storm 05-14-01 Auto sampler 0.009J 0.013J 0.01J 0.001J <0.011 <0.031 <0.13J 0.12J

Storm 10-08-01 Auto sampler .1J .015J .004J <.14 <.011 <.14 .02J .015J

Base flow 06-18-01 DH-81 .0038J .0043J .01J <.022 .074 .065J .0061J .0086J

Base flow 09-17-01 DH-81 <.10 <.09 .004J <.02 .005J <.02 <.18 <.15

Issaquah Creek (site 6)

Stream 

condition Date Collection method

2,4-D 2-Butoxyethanol 

phosphate

4-Nitrophenol Atrazine, 

filtered

Carbaryl, 

filtered 

Diazinon

filtered unfiltered filtered unfiltered filtered unfiltered

Storm 05-14-01 Auto sampler 0.077J 0.082J – 0.029NJ 0.024NJ 0.002J 0.018J <0.005 <0.022

Storm 10-08-01 Auto sampler .4 .41 0.21NJ .18J <.46 <.007 <.041 .011 .025J

Baseflow 06-18-01 DH-81 <.16 <.16 – .029J .056J <.007 <.041 <.005 <.017

Baseflow 09-17-01 DH-81 <.17 <.19 – .038J .032J <.007 <.041 <.005 <.016

Stream 

condition Date Collection method

Dichlobenil Diuron MCPA MCPP

filtered unfiltered filtered unfiltered filtered unfiltered filtered unfiltered

Storm 05-14-01 Auto sampler <0.053 <0.054 0.24NJ 0.11NJ <0.50 <0.45 0.076J 0.057J

Storm 10-08-01 Auto sampler .08 .21 <.19 <.19 .05J .073J .33J .39J

Baseflow 06-18-01 DH-81 <.042 <.039 <.13 <.13 <.32 <.32 <.32 <.32

Baseflow 09-17-01 DH-81 <.042 <.042 <.13 <.12 <.35 <.38 <.35 <.38

Stream 

condition Date Collection method

Pentachlorophenol Prometon Trichlopyr Trifluralin, 

filtered filtered unfiltered filtered unfiltered filtered unfiltered

Storm 05-14-01 Auto sampler 0.023J 0.04J 0.01J 0.0071J 0.037J 0.04J <0.009

Storm 10-08-01 Auto sampler .06J .078J .01J <.031 .06J .063J .004J

Baseflow 06-18-01 DH-81 .0048J .0045J <.01 <.021 .0045J .0055J <.009

Baseflow 09-17-01 DH-81 <.087 <.095 <.01 <.019 <.15 <.16 <.009

Table 6. Concentrations of pesticides and pesticide transformation products detected in stream water samples during storms and 

during baseflow at sites on streams in King County, Washington, 1998–2003.

[Locations of sites are shown in figure 1. All concentrations are in micrograms per liter. Concentrations: J, estimated value; M, identified, but value is too low to 

quantify; N, there is evidence that the analyte is present. <, less than; –, not analyzed]

14 Pesticides Detected in Urban Streams in King County, Washington, 1998–2003
Juanita Creek (site 5)

Stream 

condition Date Time Collection method

2,4-D, 

unfiltered

2,6-Dichlorobenzamide, 

unfiltered

4,4’-DDD, 

unfiltered

4,4’-DDE, 

unfiltered

4,4’-DDT, 

unfiltered

4-Nitrophenol, 

unfiltered

Atrazine, 

filtered

Bromacil, 

unfiltered

Carbaryl, 

filtered 

Storm 04-23-98 1340 DH-81 1.0 0.005NJ – – – 0.29 <0.001 <0.079 <0.003

Storm 04-23-98 1930 DH-81 .63 .008NJ – – – .25 .004 <.082 .022J

Storm 04-23-98 2110 DH-81 .59 <.081 – – – .22 <.001 <.081 .017J

Storm 06-24-99 0750 DH-81 .52 .1J <0.011 <0.011 <0.011 .086J <.001 <.079 .023J

Storm 10-08-99 0930 DH-81 .64 .016J <.011 <.011 <.011 <.14 <.001 <.082 .026J

Storm 11-16-99 1030 DH-81 .03J – .0028J .0027J .084J .098NJ <.001 <.081 <.003

Baseflow 08-17-99 1040 DH-81 .11 .1J <.011 <.011 .002J <.14 .005 .009J <.003

Stream 

condition Date Time Chlorpyrifos, unfiltered

Diazinon Dicamba, 

unfiltered

Dichlobenil, 

unfiltered

Dichlorprop, 

unfiltered

Diuron, 

unfiltered

EPTC, 

filtered 

Lindane, 

filtered 

Malathion, 

filtered filtered unfiltered

Storm 04-23-98 1340 – 0.242 – 0.09 0.081J <0.046 <0.16J <0.002 <0.004 0.087

Storm 04-23-98 1930 – .276 – .034J .54 <.045 <.12J <.010 .034 .073

Storm 04-23-98 2110 – .309 – .041 .18 <.045 <.12J .009 .03 .071

Storm 06-24-99 0750 0.004NJ .182 0.14 .025J .31 .021J .39NJ <.002 <.004 <.010

Storm 10-08-99 0930 .002NJ .179 .12 .028J .062 <.086 <.12 <.002 <.004 .01

Storm 11-16-99 1030 <.016 .013 .015J <.083 .039 .013NJ <.12 <.002 <.004 <.005

Baseflow 08-17-99 1040 <.016 .014 .021J <.079 .014J <.087 <.12J <.002 <.004 <.005

Stream 

condition Date Time Malathion, unfiltered

MCPA, 

unfiltered

MCPP, 

unfiltered

Metolachlor, 

filtered 

Pentachlorophenol, 

unfiltered

Prometon Simazine, 

filtered

Trichlopyr, 

unfiltered

Trifluralin, 

filtered filtered unfiltered

Storm 04-23-98 1340 – 0.38 0.74 <0.002 0.04NJ 0.05 <0.02 <0.005 0.037NJ 0.002J

Storm 04-23-98 1930 – .12 .39 <.002 .076 .09 <.02 .014 .17 .003J

Storm 04-23-98 2110 – .14 .44 .004 .077 .08 <.02 .026 .1 .003J

Storm 06-24-99 0750 0.004NJ .025NJ .69 .142 .11 .08 .017J <.005 .29 .006

Storm 10-08-99 0930 <.016 .092J .37 <.002 .11 .09 <.02 .007 .26 <.002

Storm 11-16-99 1030 <.016 <.17 .075J <.002 .04J .03 <.02 .056 .04J <.002

Baseflow 08-17-99 1040 <.016 <.16 .028J <.002 .013J .07 .057J .004J .12 <.002

Kelsey Creek (site 4)

Stream 

condition Date Collection method

2,4-D, 

unfiltered

4-Nitrophenol, 

unfiltered

Aminomethylphosphonic 

acid, filtered

Carbaryl, 

filtered 

Desulfinylfipronil amide, 

filtered

Diazinon, 

filtered

Dicamba, 

unfiltered

Dichlobenil, 

unfiltered

Storm 10-16-03 Auto sampler 0.19 0.047NJ <0.1 <0.041 <0.009 <0.005 0.014NJ 0.12

Storm 11-18-03 Auto sampler .13J .1NJ <.1 .009J .004J .024 .012NJ <.31J

Baseflow 07-08-03 DH-81 .021NJ <.28 .1 <.041 <.009 <.005 .011NJ <.065

Baseflow 08-05-03 DH-81 .15J <.27 .1 <.041 <.009 <.005 .01J <.063

Stream 

condition Date Collection method

Fipronil, 

filtered 

Glyphosate, 

filtered

MCPA, 

unfiltered

MCPP, 

unfiltered

Pentachlorophenol, 

unfiltered

Prometon, 

filtered

Trichlopyr, 

unfiltered

Trifluralin, 

filtered

Storm 10-16-03 Auto sampler 0.004J 0.5 0.061J 0.1J 0.042J 0.02 0.12 0.005J

Storm 11-18-03 Auto sampler <.016 .7 .035J .039J .075J .008 .091J .006J

Baseflow 07-08-03 DH-81 <.007 .4 <.33 <.33 .02J <.01 .031J <.009

Baseflow 08-05-03 DH-81 <.007 <.1 <.31 .071J .021J <.01 .033J <.009

Table 6. Concentrations of pesticides and pesticide transformation products detected in stream water samples during storms and 

during baseflow at sites on streams in King County, Washington, 1998–2003.—Continued

[Locations of sites are shown in figure 1. All concentrations are in micrograms per liter. Concentrations: J, estimated value; M, identified, but value is too low to 

quantify; N, there is evidence that the analyte is present. <, less than; –, not analyzed]

Table 6 15
Lewis Creek (site 7)

Stream 

condition Date Time Collection method 2,4-D, unfiltered

2,6-Dichlorobenzamide, 

unfiltered

4-Nitrophenol, 

unfiltered

Atrazine, 

filtered

Chlorpyrifos, 

unfiltered

Storm 04-23-98 1340 DH-81 0.027J 0.004NJ 0.069 <0.001 –

Storm 04-23-98 1550 DH-81 <.041 .016J .021J .002J –

Storm 04-23-98 2020 DH-81 .12 .039J .048J .002J –

Storm 06-24-99 1110 DH-81 .54 .091J .058NJ <.001 0.004NJ

Stream 

condition Date Time Desethylatrazine, filtered

Diazinon Dicamba, 

unfiltered

EPTC, 

filtered

Malathion, 

filtered unfiltered unfiltered

Storm 04-23-98 1340 <0.002 0.238 – <0.04 0.005 –

Storm 04-23-98 1550 <.002 .105 – <.041 <.002 –

Storm 04-23-98 2020 .002J .094 – <.04 <.002 –

Storm 06-24-99 1110 <.002 .073 0.049J .032J <.002 0.002NJ

Stream 

condition Date Time MCPA, unfiltered

MCPP, 

unfiltered

Pentachlorophenol, 

unfiltered

Prometon, 

filtered 

Simazine, 

filtered

Trichlopyr, 

unfiltered

Storm 04-23-98 1340 0.018NJ 0.061NJ 0.016J <0.02 <0.005 <0.034

Storm 04-23-98 1550 .041J .11 <.02 .01J .002J <.034

Storm 04-23-98 2020 .013NJ .13 .021NJ .01J <.005 .022NJ

Storm 06-24-99 1110 .079J .77 .024NJ .01J <.005 .18

Little Bear Creek (site 9)

Stream 

condition Date Time Collection method

2,4-D, 

unfiltered

2,6-Dichlorobenzamide, 

unfiltered

4-Nitrophenol, 

unfiltered

Aminomethylphosphonic 

acid, filtered 

Atrazine, 

filtered

Bromacil, 

unfiltered

Caffeine, 

unfiltered

Carbaryl, 

filtered 

Desethylatrazine, 

filtered

Storm 05-03-00 1100 Auto sampler 0.23 – <0.14 – 0.005 <0.081 – 0.018J <0.002

Storm 05-03-00 1340 DH-81 .18 – <.15 – <.005 <.083 – <.020 <.002

Storm 10-09-00 1315 Auto sampler .52 – .25 – <.007 <.095 – <.041 <.006

Storm 06-28-02 2145 Auto sampler 3.3 – <.33 0.4 <.008 <.086 0.37J .032J <.006

Storm 11-12-02 1230 Auto sampler .37 – .23J .1 <.007 <.069 – .007J <.006

Baseflow 06-27-00 1130 DH-81 <.100 – <.18 – <.001 <.089 – <.003 .003J

Baseflow 07-10-02 1115 DH-81 .12J – <.27 <.1 .002J <.083 – <.041 <.006

Baseflow 08-21-02 1130 DH-81 .041J 0.01J <.29 .1 <.007 .018J – <.041 <.006

Stream 

condition Date Time

Diazinon Dicamba, 

unfiltered

Dichlobenil, 

unfiltered

Dichlorprop, 

unfiltered

Diuron, 

unfiltered

Glyphosate, 

filtered

Malathion, 

filtered filtered unfiltered

Storm 05-03-00 1100 0.008 0.01J <0.078 0.029J <0.086 <0.24 – <0.005

Storm 05-03-00 1340 .007 .0066J <.083 .011J <.092 <.25 – <.005

Storm 10-09-00 1315 <.005 .0098J .012J .034J <.12 <.21 – <.027

Storm 06-28-02 2145 .004J <.017J .041NJ .019J .2J <.13 2.0 .016J

Storm 11-12-02 1230 .005 <.014 .032NJ .095 <.17 <.10 .3 <.027

Baseflow 06-27-00 1130 <.002 .0057J <.1 .06 <.11 <.13 – <.005

Baseflow 07-10-02 1115 .004J .047J <.16 <.042 <.17 <.13 <.1 <.027

Baseflow 08-21-02 1130 <.005 <.017 .0034NJ <.043 <.18 .084NJ .1 <.027

Stream 

condition Date Time MCPA, unfiltered

MCPP, 

unfiltered

Napropamide, 

filtered

Pentachlorophenol, 

unfiltered

Prometon, 

filtered

Simazine, 

filtered

Tebuthiuron, 

filtered

Trichlopyr, 

unfiltered

Storm 05-03-00 1100 0.02NJ 0.17 <0.003 0.092 0.01J <0.010 0.01 0.18

Storm 05-03-00 1340 <.17 .057J <.003 .027J .01J <.005 .02 .15

Storm 10-09-00 1315 <.23 .20J <.007 .052J .02 <.011 <.02 .74

Storm 06-28-02 2145 <.38 .29J <.007 .072J .01J .011 <.02 2.7

Storm 11-12-02 1230 <.32 .029J .015 .058J .01J <.005 .03 .39

Baseflow 06-27-00 1130 <.20 <.20 <.003 <.050 M .005 .01J <.084

Baseflow 07-10-02 1115 .016J .025J <.007 .0063NJ .01J <.005 .01J 0.048J

Baseflow 08-21-02 1130 .047J .039J <.007 .012J <.01 <.005 <.02 0.031J

Table 6. Concentrations of pesticides and pesticide transformation products detected in stream water samples during storms and 

during baseflow at sites on streams in King County, Washington, 1998–2003.—Continued

[Locations of sites are shown in figure 1. All concentrations are in micrograms per liter. Concentrations: J, estimated value; M, identified, but value is too low to 

quantify; N, there is evidence that the analyte is present. <, less than; –, not analyzed]

16 Pesticides Detected in Urban Streams in King County, Washington, 1998–2003
Lyon Creek at 178th (site 12)

(Replicate sample was collected on 06/24/99; see table 4)

Stream 

condition Date Time Collection method

2,4-D, 

unfiltered

2,6-Dichlorobenzamide, 

unfiltered

4,4’-DDD, 

unfiltered

4,4’-DDE, 

unfiltered

4,4’-DDT, 

unfiltered

4-Nitrophenol, 

unfiltered

Atrazine, 

filtered

Carbaryl, 

filtered

Storm 05-14-98 0540 DH-81 0.29 0.031J – – – 0.047NJ 0.019 0.012J

Storm 05-14-98 0640 DH-81 .14 .031J – – – .036J .021 .011J

Storm 06-24-99 0800 DH-81 .34 .086J <0.011 <0.011 <0.011 .1J <.001 .121J

Storm 10-08-99 0940 DH-81 .69 .023J <.012 <.012 <.012 <.14 <.001 <.020

Storm 11-16-99 1730 DH-81 .034J – .0021J .0021J .041J .12NJ <.001 <.003

Baseflow 08-17-99 1240 DH-81 .015J .051J <.011 <.011 .002J <.15 .004 <.003

Stream 

condition Date Time Chlorpyrifos, unfiltered

Diazinon Dicamba, 

unfiltered

Dichlobenil, 

unfiltered

Dichlorprop, 

unfiltered

Diuron, 

unfiltered

Malathion, 

filtered filtered unfiltered

Storm 05-14-98 0540 – 0.305 – 0.036J 0.061 <0.043 <0.12 0.033

Storm 05-14-98 0640 – .425 – .02J .063 .0081J <.12 .037

Storm 06-24-99 0800 0.003NJ .194 0.16 .027J .24 .032J .007NJ <.030

Storm 10-08-99 0940 <.017 .073 .045 .016J .31 <.086 <.13 .017

Storm 11-16-99 1730 <.016 .014 .014J <.081 .065 <.089 <.12 <.005

Baseflow 08-17-99 1240 <.016 <.002 <.016 <.085 .033 <.093 <.12J <.005

Stream 

condition Date Time Malathion, unfiltered

MCPA, 

unfiltered

MCPP, 

unfiltered

Napropamide, 

filtered

Pentachlorophenol, 

unfiltered

Prometon, 

filtered

Simazine Trichlopyr, 

unfiltered filtered unfiltered

Storm 05-14-98 0540 – 0.025NJ 0.15 0.016 0.036 0.03 4.73 3.3 0.13

Storm 05-14-98 0640 – .026J .13 .014 .042 .04 4.99 3.3 .091

Storm 06-24-99 0800 0.004NJ <.18 .57 <.003 .1 .11 1.03 .25 .18

Storm 10-08-99 0940 <.017 <.16 .52 <.030 .066 .02 .223 <.021J .29

Storm 11-16-99 1730 <.016 <.16 .18 <.003 .098 .02 <.005 <.020J .058J

Baseflow 08-17-99 1240 <.016 <.17 <.17 <.003 .013J .01J .416 .28 .041J

Lyon Creek at Lake Forest Park (site 13)

Stream 

condition Date Time Collection method

2,4-D, 

unfiltered

4-Nitrophenol, 

unfiltered

Atrazine Bromacil, 

unfiltered

Carbaryl, 

filtered

Chlorpyrifos, 

unfiltered filtered unfiltered

Storm 05-03-00 0930 Auto sampler 0.2 <0.15 0.017 0.0099J <0.081 0.207J 0.003NJ

Storm 05-03-00 1345 DH-81 .29 <.16 .008 .014NJ .013NJ .164J .003NJ

Storm 10-09-00 1230 Auto sampler .2 .29 <.007 <.071J <.11 <.060 <.022

Baseflow 06-27-00 1115 DH-81 <.11 <.19 <.001 .004NJ .05J <.003 <.018

Stream 

condition Date Time Desethylatrazine, filtered

Diazinon Dicamba, 

unfiltered

Dichlobenil, 

unfiltered

MCPA, 

unfiltered

MCPP, 

unfiltered filtered unfiltered

Storm 05-03-00 0930 <0.002 0.059 0.054 <0.083 0.11 0.056J 0.084J

Storm 05-03-00 1345 <.002 .099 .13 <.089 .1 .036NJ .18

Storm 10-09-00 1230 <.006 .044 .031J .026J .071 <.22 .39

Baseflow 06-27-00 1115 .003J .005 .0072J <.11 .013J <.21 <.21

Stream 

condition Date Time Pentachlorophnol, unfiltered

Prometon, 

filtered

Simazine Tebuthiuron, 

filtered

Trichlopyr, 

unfiltered

Trifluralin, 

filtered filtered unfiltered

Storm 05-03-00 0930 0.026J 0.03 0.033 0.015J <0.01 0.1 <0.002

Storm 05-03-00 1345 .034J .04 .045 .046 <.01 .061J <.002

Storm 10-09-00 1230 .12 .02 .1 <.028 <.02 .1 <.009

Baseflow 06-27-00 1115 <.054 .01J .008 <.022 .01J <.090 .003J

Table 6. Concentrations of pesticides and pesticide transformation products detected in stream water samples during storms and 

during baseflow at sites on streams in King County, Washington, 1998–2003.—Continued

[Locations of sites are shown in figure 1. All concentrations are in micrograms per liter. Concentrations: J, estimated value; M, identified, but value is too low to 

quantify; N, there is evidence that the analyte is present. <, less than; –, not analyzed]

Table 6 17
May Creek (site 3)

Stream 

condition Date Collection method

2,4-D, 

unfiltered

4-Nitrophenol, 

unfiltered

Carbaryl, 

filtered

Diazinon, 

filtered

Dicamba, 

unfiltered

Glyphosate, 

filtered 

Storm 10-16-03 Auto sampler 0.056J 0.047NJ 0.027J 0.007 <0.16 0.2

Storm 11-18-03 Auto sampler .073J .064NJ <.041 <.005 .0075NJ .2

Baseflow 07-08-03 DH-81 <.16 <.28 <.041 <.005 <.16 <.1

Baseflow 08-05-03 DH-81 <.16 <.29 <.041 <.005 <.16 <.1

Stream 

condition Date Collection method

MCPP, 

unfiltered

Metolachlor, 

filtered 

Pentachlorophenol, 

unfiltered

Prometon, 

filtered 

Trichlopyr, 

unfiltered

Storm 10-16-03 Auto sampler 0.047J 0.273 0.066J 0.01J 0.062J

Storm 11-18-03 Auto sampler .05 J .095 .037J .01 .031J

Baseflow 07-08-03 DH-81 <.32 .011J <.08 <.01 <.13

Baseflow 08-05-03 DH-81 <.33 <.013 <.082 <.01 <.14

North Creek (site 10)

Stream 

condition Date Collection method

2,4-D, 

unfiltered

2,6-Dichlorobenzamide, 

unfiltered

4-Nitrophenol, 

unfiltered

Atrazine,

 filtered

Caffeine, 

unfiltered

Carbaryl, 

filtered

Storm 06-28-02 Auto sampler 0.47 – <0.32 <0.007 0.23J 0.017J

Storm 11-12-02 Auto sampler <.044 – .13J <.007 – .011J

Baseflow 07-10-02 DH-81 .053J – <.30 .002J – .010J

Baseflow 08-21-02 DH-81 <.17 0.019J <.30 <.007 – <.041

Stream 

condition Date Collection method

Diazinon Dicamba, 

unfiltered

Dichlobenil, 

unfiltered

Glyphosate, 

filtered 

Malathion, 

filtered 

MCPP, 

filtered unfiltered unfiltered

Storm 06-28-02 Auto sampler 0.007 <0.020J 0.035NJ 0.021J 0.1 0.010J 0.24J

Storm 11-12-02 Auto sampler .011 <.014 <.19 .024 <.1 <.027 .091J

Baseflow 07-10-02 DH-81 .009 .076J <.17 .003J <.1 <.027 .037J

Baseflow 08-21-02 DH-81 <.005 .14J <.17 <.045 <.1 <.027 .014NJ

Stream 

condition Date Collection method

Pentachlorophenol, 

unfiltered

Prometon Simazine,

filtered

Tebuthiuron, 

filtered 

Trichlopyr, 

filtered unfiltered unfiltered

Storm 06-28-02 Auto sampler 0.11 0.04 <0.025 0.007 <0.02 0.11J

Storm 11-12-02 Auto sampler .058J .02 <.018 .008 <.02 .11J

Baseflow 07-10-02 DH-81 .0098J .02 .04NJ .052 .02J .27

Baseflow 08-21-02 DH-81 .014J <.01 <.022 <.005 <.02 .017NJ

Rock Creek (site 2)

Stream 

condition Date Collection method

4-Nitrophenol, 

unfiltered

Dicamba, 

unfiltered

Storm 05-14-98 DH-81 <0.071 <0.041

Storm 06-24-99 DH-81 .037NJ .011J

Storm 10-08-99 DH-81 <.14 <.081

Storm 11-16-99 DH-81 <.15 <.083

Baseflow 08-17-99 DH-81 <.16 <.089

Swamp Creek (site 11)

Stream 

condition Date Time Collection method

2,4-D, 

unfiltered

4-Nitrophenol, 

unfiltered

Atrazine, 

unfiltered

Diazinon Dichlobenil, 

unfiltered

Malathion

filtered unfiltered filtered unfiltered

Storm 05-03-00 1200 Auto sampler 0.058J <0.14 <0.020 0.025 0.019 0.025J 0.032 0.013J

Storm 05-03-00 1500 DH-81 .055J <.15 <.020 .03 .021 .018J .021 .0069J

Storm 10-09-00 1340 Auto sampler .12 .17J <.023 .029 .017J .023J <.027 <.018

Baseflow 06-27-00 1310 DH-81 <.11 <.19 .007NJ .004J .0044J .021J <.005 <.019

Stream 

condition Date Time MCPA, unfiltered

MCPP, 

unfiltered

Pentachlorophenol, 

unfiltered

Prometon, 

filtered

Simazine, 

filtered

Trichlopyr, 

unfiltered

Storm 05-03-00 1200 0.026J 0.068J 0.02J 0.02 <0.010 0.12

Storm 05-03-00 1500 .031J .066J .014J .02 <.010 .13

Storm 10-09-00 1340 <.22 .14J .079 .01J <.011 .11

Baseflow 06-27-00 1310 <.21 <.21 <.054 .01J .007 <.09

Table 6. Concentrations of pesticides and pesticide transformation products detected in stream water samples during storms and 

during baseflow at sites on streams in King County, Washington, 1998–2003.—Continued

[Locations of sites are shown in figure 1. All concentrations are in micrograms per liter. Concentrations: J, estimated value; M, identified, but value is too low to 

quantify; N, there is evidence that the analyte is present. <, less than; –, not analyzed]

18 Pesticides Detected in Urban Streams in King County, Washington, 1998–2003
Taylor Creek (site 1)

Stream 

condition Date Collection method 2,4-D, unfiltered

4-Nitrophenol, 

unfiltered

Dicamba, 

unfiltered

Glyphosate, 

filtered

MCPA, 

unfiltered

Storm 10-16-03 Auto sampler 0.11J 0.035NJ 0.014NJ 0.2 0.027J

Storm 11-18-03 Auto sampler .049J <.27 .0078NJ .1 .023NJ

Baseflow 07-08-03 DH-81 <.18 <.32 <.18 <.1 <.36

Baseflow 08-05-03 DH-81 <.16 <.28 <.16 <.1 <.33

Stream 

condition Date MCPP, unfiltered

Metolachlor, 

filtered 

Pentachlorophenol, 

unfiltered

Prometon, 

filtered 

Trichlopyr, 

unfiltered

Storm 10-16-03 0.077J 0.010J 0.029J 0.19 0.061J

Storm 11-18-03 .056J .007J .091 .03 .045J

Baseflow 07-08-03 <.36 <.013 .011J <.01 <.15

Baseflow 08-05-03 <.33 <.013 .0049J .01J <.14

Unnamed Site @ 124th (site 14)

Stream 

condition Date Collection method

2,4-D, 

unfiltered

2,6-Dichlorobenzamide, 

unfiltered

4-Nitrophenol, 

unfiltered

Aminometylphosphonic 

acid, filtered 

Atrazine, 

filtered

Caffeine, 

unfiltered

Carbaryl, 

filtered

Carbofuran

filtered unfiltered

Storm 06-28-02 Dip 0.45 – <0.29 0.5 <0.007 0.31J 0.098J <0.020 –

Storm 11-12-02 Dip .041J – .23J .5 <.007 .11J .047J <.020 –

Baseflow 09-11-00 Dip .28 0.21J <.19 – <.006 – <.003 .229 0.089NJ

Baseflow 07-10-02 Dip .16J .11J <.30 .8 .003J – .064J <.020 –

Baseflow 08-21-02 Dip .12J .016J <.27 1.3 .004J – .035J <.020 –

Stream 

condition Date Chlorpyrifos Diazinon Dicamba, unfiltered

Dichlobenil, 

unfiltered

Dichlorprop, 

unfiltered

Diuron, 

unfiltered filtered unfiltered filtered unfiltered

Storm 06-28-02 0.012 <0.016J 0.005 0.21J <0.16 0.079 0.033J <0.12

Storm 11-12-02 .008 <.014 <.005 <.014 .088J <.036 <.18 <.11

Baseflow 09-11-00 .005 <.019 .586 .47 .38 .041J <.12 .052NJ

Baseflow 07-10-02 .015 .0028J .014 .19J <.17 <.001 <.19 <.13

Baseflow 08-21-02 .015 .0089J <.005 <.015 <.15 .0082J <.17 .075NJ

Stream 

condition Date Ethofumesate, unfiltered

Glyphosate, 

filtered

Malathion MCPA, 

unfiltered

MCPP, 

unfiltered

Metalaxyl, 

unfiltered filtered unfiltered

Storm 06-28-02 – 1.2 0.216 0.12J <0.33 0.092J <0.12

Storm 11-12-02 – .8 <.027 <.014 .079J .079NJ <.11

Baseflow 09-11-00 2.4NJ – <.005 <.019 <.22 <.22 .15

Baseflow 07-10-02 – .8 .029 .0045J <.34 <.34 <.13

Baseflow 08-21-02 – 1.3 <.027 <.015 <.31 .048J <.11

Stream 

condition Date Metolachlor, filtered 

Oxadiazon, 

unfiltered

Pentachlorophenol, 

unfiltered

Prometon, 

filtered

Simazine, 

filtered

Tebuthiuron, 

filtered

Trichlopyr, 

unfiltered

Trifluralin, 

filtered

Storm 06-28-02 <0.013 – 0.13 0.03 <0.005 <0.02 0.31 <0.009

Storm 11-12-02 <.013 – .092 .01J .01 .05 .12J <.009

Baseflow 09-11-00 .007 – .029NJ .01J <.005 .08J .28 .003J

Baseflow 07-10-02 .004J – .021NJ .01J .007 .06 .036J <.009

Baseflow 08-21-02 .007J 0.066J .015NJ .03 .007 .02 .11J <.009

Table 6. Concentrations of pesticides and pesticide transformation products detected in stream water samples during storms and 

during baseflow at sites on streams in King County, Washington, 1998–2003.—Continued

[Locations of sites are shown in figure 1. All concentrations are in micrograms per liter. Concentrations: J, estimated value; M, identified, but value is too low to 

quantify; N, there is evidence that the analyte is present. <, less than; –, not analyzed]

Table 6 19
Manuscript approved for publication, September 17, 2004

Prepared by the Publishing Group, U.S. Geological Survey, 

Washington Water Science Center, Tacoma, Washington

USGS Publishing staff

Linda S. Rogers

Bill Gibbs 

Bob Crist

Bobbie Jo Richey

For more information concerning the research in this report, contact 

the Washington Water Science Center Director, 

U.S. Geological Survey, 1201 Pacific Avenue – Suite 600 

Tacoma, Washington 98402

http://wa.water.usgs.gov
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