Occurrence of Selected Trace Elements

and Organic Compounds and Their

Relation to Land Use in The Willamette

River Basin, Oregon, 1992–94

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 96–4234

Prepared in cooperation with

OREGON DEPARTMENT OF ENVIRONMENTAL QUALITY,

WILLAMETTE RIVER TECHNICAL ADVISORY STEERING COMMITTEE, and

NATIONAL WATER-QUALITY ASSESSMENT PROGRAM
Cover photograph. Looking upstream at the Willamette River with Mt. Hood and Portland 

in the background, February 7, 1993. (Photograph by Dennis A. Wentz, U.S. Geological S
i

Occurrence of Selected Trace Elements an

Organic Compounds and Their Relation to

Land Use in The Willamette River Basin,

Oregon, 1992–94

By Chauncey W. Anderson, Frank A. Rinella and

Stewart A. Rounds

U.S. GEOLOGICAL SURVEY

Water-Resources Investigations Report 96–4234

Prepared in cooperation with

OREGON DEPARTMENT OF ENVIRONMENTAL QUALITY,

WILLAMETTE RIVER TECHNICAL ADVISORY STEERING COMMITTEE, and

NATIONAL WATER-QUALITY ASSESSMENT PROGRAM

Portland, Oregon

1996
ii

U.S. DEPARTMENT OF THE INTERIOR

BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY

Gordon P. Eaton, Director

______________________________________________________________________________________________

For additional information

write to:

District Chief

U.S. Geological Survey, WRD

10615 S.E. Cherry Blossom Drive

Portland, OR 97216

Copies of this report can

be purchased from:

U.S. Geological Survey

Branch of Information Services

Box 25286, Federal Center

Denver, CO 80225

The 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.
iii

CONTENTS

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

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

Scope and Objectives .................................................................................................................................3

Acknowledgments .....................................................................................................................................3

Description of Study Area .....................................................................................................................................3

Climate and Hydrology .............................................................................................................................5

Land Use, Crop Types, and Pesticide Use .................................................................................................6

Study Design and Methods ...................................................................................................................................9

Objectives ..................................................................................................................................................9

Sampling Locations, Dates, and Constituents ...........................................................................................9

Methods ...................................................................................................................................................12

Quality Assurance ....................................................................................................................................12

Results..................................................................................................................................................................16

Hydrologic Conditions ............................................................................................................................16

Trace Elements ........................................................................................................................................17

Exceedances of Water-Quality Criteria .......................................................................................17

Relation to Land Use ....................................................................................................................20

Relation with Suspended Sediment and Streamflow ....................................................................23

Organic Compounds ................................................................................................................................27

Volatile Organic Compounds .......................................................................................................27

Organochlorine Compounds ........................................................................................................27

Exceedances of Water-Quality Criteria ............................................................................28

Relation to Land Use ........................................................................................................28

Sediment-Water Partitioning ............................................................................................31

Dissolved Pesticides .....................................................................................................................32

Exceedances of Water-Quality Criteria ............................................................................32

Relation to Pesticide Applications and Land Use ............................................................33

Influences of Hydrologic Conditions ...............................................................................42

Summary and Conclusions ..................................................................................................................................49

References Cited .................................................................................................................................................53

Appendixes 1. Summary statistics for concentrations of selected trace elements detected in unfiltered

and filtered water at all sites during Phases I and II of the Willamette River Basin Water

Quality Study, Oregon, 1992–94 .................................................................................................59

2. Water-quality criteria used to calculate exceedances in water samples from Phase I and

Phase II of the Willamette River Basin Water Quality Study, 1992–94 ......................................60

3. Summary statistics of concentrations of volatile organic compounds detected in unfiltered

water at all sites during Phases I and II of the Willamette River Basin Water Quality

Study, Oregon, 1992–94 ..............................................................................................................61

4. Summary statistics of concentrations of organochlorine compounds from USGS schedules

1398 and 1399 detected in unfiltered water at all sites during Phases I and II of the

Willamette River Basin Water Quality Study, Oregon, 1992–94 ...............................................63

5. Summary statistics of concentrations of pesticides from USGS schedules 2010 and 8015

detected in filtered water at all sites during Phases I and II of the Willamette River Basin

Water Quality Study, Oregon, 1992–94 ......................................................................................64

6. Summary statistics of concentrations of pesticides from USGS schedule 2051 detected in

filtered water at all sites during Phases I and II of the Willamette River Basin Water

Quality Study, Oregon, 1992–94 .................................................................................................66

7. Explanation of calculations for theoretical equilibrium partitioning of DDT and metabolite

compound ....................................................................................................................................68
iv

FIGURES

1. Map showing the Willamette River Basin, Oregon ...................................................................................4

2. Graph showing monthly distribution of daily mean streamflow in the Willamette River at Salem,

Oregon, 1975–94 water years ....................................................................................................................5

3. Map showing sampling sites for Phases I and II of the Willamette River Basin Water Quality

Study, Oregon, 1992–94...........................................................................................................................11

4.–15. Graphs showing:

4. Daily precipitation at Portland and Eugene during Phase II of the Willamette River Basin

Water Quality Study, Oregon, 1994 ....................................................................................................18

5. Percent of time daily mean streamflows were exceeded and instantaneous streamflows during

sampling at four sites during Phase II of the Willamette River Basin Water Quality Study,

Oregon, 1994 .......................................................................................................................................19

6. Concentrations of selected trace elements in unfiltered water detected at different site types

during Phases I and II of the Willamette River Basin Water Quality Study, Oregon, 1992–94 .........22

7. Relations of trace-element concentrations in unfiltered water with suspended-sediment

concentrations at urban sites in the Willamette River Basin, Oregon, 1992–94 .................................24

8. Unfiltered water and suspended concentrations of chromium, copper, and lead compared with

filtered water concentrations in samples collected during Phases I and II in the Willamette

River Basin Water Quality Study, Oregon, 1992–94 ..........................................................................26

9. Concentrations of selected organochlorine compounds detected in unfiltered water in relation to

various land uses during Phases I and II of the Willamette River Basin Water Quality Study,

Oregon, 1992–94 .................................................................................................................................30

10. Observed and equilibrium fraction of DDT and metabolites present in suspended phase for

four samples during Phase II of the Willamette River Basin Water Quality Study, Oregon,

1994 ....................................................................................................................................................32

11. Concentrations of selected pesticides primarily associated with urban land use during

Phases I and II of the Willamette River Basin Water Quality Study, Oregon, 1992–94.....................35

12. Concentrations of selected pesticides primarily associated with agricultural land use during

Phases I and II of the Willamette River Basin Water Quality Study, Oregon, 1992–94.....................36

13. Concentrations of selected pesticides associated with both agricultural and urban land uses

during Phases I and II of the Willamette River Basin Water Quality Study, Oregon, 1992–94 .........37

14. Detection frequencies for selected pesticides at northern agricultural, southern agricultural,

and urban sites during Phase II of the Willamette River Basin Water Quality Study, Oregon,

1994 .....................................................................................................................................................38

15. Comparison of spring and fall pesticide detection frequencies at northern agricultural,

southern agricultural, and urban sites during Phase II of the Willamette River Basin Water

Quality Study, Oregon, 1994...............................................................................................................39

16. Map showing number of pesticides in filtered water detected at sites in the Willamette River

Basin during Phases I and II of the Willamette River Basin Water Quality Study, Oregon,

1992–94 ...................................................................................................................................................41

17.–18. Graphs showing:

17. Response of (A) flow and concentrations and (B) flow and loads of suspended sediment

and three organic pesticides to the first fall storms at Johnson Creek during Phase II of the

Willamette River Basin Water Quality Study, Oregon, 1994............................................................44

18. Response of (A) flow and concentrations and (B) flow and loads of suspended sediment and

three organic pesticides to the first fall storms at Willamette River at Portland during

Phase II of the Willamette River Basin Water Quality Study, Oregon, 1994 ....................................46
v

TABLES

1. Constituent groups and sample media analyzed in Phases I and II of the Willamette River Basin

Water Quality Study, Oregon, and discussed in this report...........................................................................3

2. Percentages of forested, agricultural, and urban land upstream of selected locations in the

Willamette River Basin .................................................................................................................................7

3. Guidelines used to classify sampling sites according to upstream land use ................................................ 7

4. Acres of crops, by county, in the Willamette River Basin, Oregon, 1987 .................................................. 8

5. Annual usage rates of chemicals to control weeds and pests, by county, in the Willamette

River Basin, Oregon, 1987 .........................................................................................................................10

6. Sampling plan for data used in this report and collected during Phase I of the Willamette River

Basin Water Quality Study, Oregon, 1992–93 ............................................................................................12

7. Sampling plan for Phase II of the Willamette River Basin Water Quality Study, Oregon,

spring 1994 ..................................................................................................................................................13

8. Sampling plan for Phase II of the Willamette River Basin Water Quality Study, Oregon, fall 1994 .........14

9. Exceedances of State of Oregon criteria for trace elements in unfiltered and filtered water for streams

sampled during Phases I and II of the Willamette River Basin Water Quality Study, Oregon,

1992–94 ......................................................................................................................................................21

10. Correlations of detected trace-element concentrations in unfiltered water with suspended-sediment

concentrations for samples from urban sites during Phases I and II of the Willamette River Basin

Water Quality Study, Oregon, 1992–94 .....................................................................................................23

11. Summary statistics for detected unfiltered-water concentrations of volatile organic compounds in the

Willamette River Basin during Phases I and II of the Willamette River Basin Water Quality Study,

Oregon, 1992–94 .........................................................................................................................................28

12. Exceedances of Oregon Department of Environmental Quality (ODEQ) criteria for organic

chemicals in water for streams sampled during Phases I and II of the Willamette River Basin

Water Quality Study, Oregon, 1992–94 ......................................................................................................29

13. Summary statistics for detected unfiltered-water concentrations of organochlorine compounds in the

Willamette River Basin during Phases I and II of the Willamette River Basin Water Quality Study,

Oregon, 1992–94 .........................................................................................................................................30

14. Summary statistics of the 25 most frequently detected pesticides in the Willamette River Basin

during Phases I and II of the Willamette River Basin Water Quality Study, Oregon, 1992–94 ................34
vi

CONVERSION FACTORS

Multiply By To obtain

A. Factors for converting International System (SI) metric units to inch/pound units

Length

meter (m) 3.281 foot

meter 1.094 yard

kilometer (km) 1.609 mile

Volume

milliliter (mL) 0.001057 quart

liter (L) 1.057 quart

liter 0.2642 gallon

Mass

gram (g) 0.03527 ounce avoirdupois

kilogram (kg) 2.205 pound avoirdupois

B. Factors for converting inch/pound units to SI metric units

Flow (volume per unit time)

cubic feet per second (ft3/s) 0.02832 cubic meter per second

C. Factors for converting SI metric units to other miscellaneous units

Concentration in Water

milligrams per liter (mg/L) 1 parts per million

micrograms per liter (μg/L) 1 parts per billion
1

Occurrence of Selected Trace Elements and Organic

Compounds and Their Relation to Land Use in The

Willamette River Basin, Oregon, 1992–94

By Chauncey W. Anderson, Frank A. Rinella, and Stewart A. Rounds

Abstract

Between 1992 and 1994, the U.S.Geological Survey conducted a study of trace elements

and organic compounds in the Willamette

River Basin, Oregon, as part of the Willamette

River Basin Water Quality Study. Low-level

analyses were performed for trace elements,

volatile organic compounds, organochlorine

compounds, and pesticides. Overall, 94 water

samples were collected from 40 sites, during

predominantly high-flow conditions, representing urban, agricultural, mixed, and forested land uses. Although most observed

concentrations were relatively low, some

exceedances of water-quality criteria for acute

and chronic toxicity and for the protection of

human health were observed.

Concentrations of chromium, copper, lead,

and zinc in unfiltered water were well correlated with concentrations of suspended sediment. The highest trace-element concentrations generally were found at urban sites

that receive a large portion of their runoff from

industrial areas, particularly at high suspended-sediment concentrations. In contrast,

concentrations of trace elements in some

urban streams draining primarily residential

areas appeared to approach a maximum as

sediment concentrations increased. Whether

this difference was due to a difference in the

nature of the suspended sediments or to different concentrations in the aqueous phases from

the two site types was not addressed.

Eight organochlorine compounds were

detected at 14 sites. Lindane, dieldrin, and

DDT or its metabolites were each detected 

about 30 percent of the samples, predominantly in samples collected from agricultur

and urban areas. Polychlorinated biphenyl

(PCB) compounds were detected in sample

from two urban sites. For samples in which

DDT and its metabolites were examined for

partitioning, the largest proportion of the ma

of DDT and its metabolites was associated

with suspended sediment. In contrast, dield

and lindane were almost completely (greate

than 99 percent) associated with the dissolv

phase.

Sixty-one of the 94 pesticides analyzed 

filtered water were documented to have bee

used in the basin in 1987; 43 of these were

detected at least once during 1992–94. An

additional five were detected that were not

documented in the 1987 estimates. Although 

comparison between the frequency of detect

pesticides and 1987 estimates of pesticide

usage in the basin showed generally little c

relation, some patterns of detections did

appear to reflect land use in the basin. Of th

25 most frequently detected pesticides, 3 we

found primarily at urban sites, 6 were found

primarily at agricultural sites, and 7 were

found at all types of sites except forested. T

four most commonly detected pesticides in t

basin, observed at all except forested site
2

types, were atrazine, metolachlor, simazine,

and diuron. A greater variety of compounds

was detected at sites in the northern portion of

the basin than in the southern portion of the

basin probably because the northern portion

has more diverse agricultural practices and a

larger urban component. Possible reasons for

the lack of agreement between pesticide detections and pesticide usage estimates include (1)

uncertainty in the usage estimates due to spatial and temporal variability or due to changes

in agricultural practices since the 1987 estimates were compiled, (2) chemical or biological transformations in the compounds after

application, (3) variable hydrologic conditions

among sites at the time of sampling, or (4) the

ability of laboratory analytical procedures to

detect low concentrations of some analytes.

Results from repeated samplings at two

sites during sequential storms in the fall of

1994 indicated that concentrations and loads

of several constituents, including suspended

sediment, suspended organic carbon, DDT,

metolachlor, and atrazine were highest during

peak flows of the first or second significant

storms of the fall. Samplings during subsequent storms indicated that instantaneous concentrations and loads were generally reduced;

however, data were not sufficient to compare

overall transport during sequential storms.

INTRODUCTION

In the 1930s and 1940s, discharges of organic

wastes to the Willamette River, Oregon, and its tributaries produced severe water-quality problems that

significantly degraded the river’s habitat, aesthetic

value, and recreational uses (Gleeson, 1972). By 1972,

basinwide efforts to improve the water quality of the

Willamette River had proven quite successful, but

some problems remained (Hines and others, 1977;

Rickert, Peterson and others, 1977; Rickert, Kennedy,

and others, 1977; F.A. Rinella and others, 1981;

Fuhrer, 1989). In its biannual water-quality assessment

report for 1990, the Oregon Department of Environmental Quality (ODEQ) listed dozens of stream

reaches in the Willamette River Basin as not supporting or only partially supporting their designated beneficial uses (Oregon Department of Environm

Quality, 1990a). These remaining problems, 

the 1987 Federal Clean Water Act amendme

1990 review of State water-quality standard

prompted the Oregon Legislature to establis

lamette River Technical Advisory Steering C

(WRTASC). Formed in 1990, this committe

ated to work with ODEQ to establish prioriti

oversee the completion of a multiphase Will

River Basin Water Quality Study (WRBWQ

referred to herein as the Willamette Study).

Composed of representatives from ODE

and local agencies, Federal agencies, indust

environmental groups, the WRTASC establi

broad range of scientific and educational go

Willamette Study (Oregon Department of E

mental Quality, 1990b). The overall objectiv

study was:

to develop a complete database for 

basin that is coupled with operative 

quality models that will enable Fed

State, and local agencies to coope

ensure the preservation and the be

uses of the Willamette River Basin 

associated biota (Tetra Tech, Inc., 

Specific work items included (1) developme

predictive models of water quality, hydrolog

sediment transport; (2) calibration of these m

using field-collected data; and (3) applicatio

biological-community-assessment methods 

biological indices to assist ODEQ in future

development of numerical biological criteria 

Tech, Inc., 1993a).

Phase I of the Willamette Study include

ments, by a variety of investigators, of disso

gen, nutrients, algae, trace elements and org

compounds, bacteria, point and nonpoint so

iment, flow, and ecological health. The U.S. 

cal Survey (USGS) participated in Phase I th

cooperative project with ODEQ focusing on 

elements and organic compounds, sediment

components of the Willamette Study (Laene

Lee, 1995; Laenen and Risley, in press). A s

of the other work was published in a series o

reports that characterize the water quality an

of pollution in the basin as well as the mode

were developed in Phase I (Tetra Tech, Inc.,

1992a, 1992b, 1993a, 1993b).
3

Phase II built upon the knowledge gained and the

models developed during Phase I. The components of

Phase II conducted by the USGS included (1) additional, basinwide investigations of the occurrence of

trace elements and organic chemicals and their relation to land use, (2) measurement of sediment oxygen

demand in the lower portion of the main-stem Willamette River (river miles 3.1 to 50.5) (Caldwell and

Doyle, 1995), and (3) quantification of the factors controlling dissolved oxygen in the upper main-stem Willamette River and selected tributaries (Pogue and

Anderson, 1995). As in Phase I, this work was part of

a cooperative agreement with ODEQ. Other Phase II

study components, conducted by Tetra Tech, Inc.,

included steady-state model calibration and data

acquisition, nonpoint-source pollution studies, ecological monitoring, and a final report integrating results

from the entire Willamette Study (Tetra Tech, Inc.,

1994).

The USGS investigation of trace elements and

organic compounds in Phases I and II was actively

coordinated with two other concurrent USGS studies:

the USGS National Water-Quality Assessment

(NAWQA) Program (Wentz and McKenzie, 1991) and

the Columbia River Bi-State Study (Fuhrer and others,

1996; Tetra Tech, Inc., 1993c). Relevant data from

these studies also are included in this report.

Scope and Objectives

This report describes an investigation of the occurrence of trace elements and organic compounds in surface waters of the Willamette River Basin. The

purposes of this report are to:

1. Document exceedances of State and/or Federal

water-quality standards for trace elements and

organic compounds in water.

2. Relate concentrations and (or) calculated

instantaneous loads of trace elements and

pesticides to land-use activities, streamflow

conditions, and, for pesticides, agricultural

practices and pesticide applications.

3. Assess the partitioning of selected trace elements

and hydrophobic pesticides between the dissolved

and suspended phases.

Table 1 shows the constituents and media that are

discussed in this report. The primary focus is on Phase

II; those constituents or media that were sampled

exclusively in Phase I of the Willamette Study are not

considered. All data from the Phase I and Phase II

trace element and organic compound investigations

addition to relevant data from the Willamette NAW

and Columbia River Bi-State programs, were published by Harrison and others (1995).

Acknowledgments

The authors express their gratitude to the follow

ing individuals and organizations: the Oregon Dep

ment of Environmental Quality, for cooperative

funding and logistical assistance; Ivan Blenderman

City of Portland Bureau of Environmental Services

for assistance in finding and gaining access to unde

ground sampling locations, regardless of weather c

ditions or the time of day; the City of Corvallis

Department of Public Works, for access to their sam

pling site at the Rock Creek Water Treatment Plant

Michael Fowler and Christa Reining of Woodward

Clyde Consultants, for access to flow data, maps, a

water-quality information for underground samplin

locations; and George Taylor, Oregon State Climat

gist, for kindly supplying precipitation data. The

WRTASC, the Association of Clean Water Agencie

and Northwest Pulp and Paper are gratefully ackno

edged for their support and their contributions to th

design of the Phase I and Phase II studies.

DESCRIPTION OF STUDY AREA

The Willamette River Basin, located in northw

ern Oregon, is bounded on the north by the Columb

River and on the west, south, and east by the Coast

Range, the Calapooya Mountains, and the Cascade

Range, respectively (fig. 3). From the confluence of 

Table 1. Constituent groups and sample media analyze

Phases I and II of the Willamette River Basin Water Qua

Study, Oregon, and discussed in this report

[✔, combination was analyzed; PCBs, polychlorinated biphenyls]

Constituent

group

Unfiltered

water

Filtered

water

Suspend

sedimen

Trace

elements ✔ ✔

Volatile organic

compounds ✔

Pesticides

and PCBs ✔✔ ✔
4

Figure 1. Willamette River Basin, Oregon.
5

Coast and Middle Forks near Eugene, the main stem

Willamette River flows 187 miles northward to the

Columbia River and drains an area of approximately

11,500 square miles. The basin includes some of the

most productive agricultural and forest lands in the

State, as well as the most heavily populated urban

areas. The three largest cities in Oregon (Portland,

Eugene, and Salem) and 68 percent of the State’s population are located in the basin. Previous reports have

described the basin’s general characteristics (Bonn and

others, 1995) and hydrogeology (McFarland, 1983;

Gonthier, 1985).

Climate and Hydrology

A temperate marine climate provides the Willamette River Basin with characteristically cool, wet

winters and warm, dry summers. Annual precipitation

ranges from about 37 inches in parts of the valley bottom to about 175 inches on the slopes of the Coast

Range and Cascade Range mountains (Taylor, 1993).

Most of the precipitation falls between November and

April; the driest months are July, August, and September. Although the higher elevations of the Cascade

Range receive a substantial amount of snowfall in t

winter, only about 35 percent of the annual runoff i

from snowmelt (Laenen and Risley, in press). Strea

flow throughout the Willamette River Basin, with t

exception of some flow regulation from the basin’s 

major reservoirs, is dominated by the seasonal patte

of rainfall (fig. 2). The low-flow period, generally

from July through September, typically accounts fo

to 5 percent of streamflow for unregulated streams 

the basin. In contrast, the high-flow period from

November to April generally accounts for 80 to 90

percent of the annual flow in streams unaffected by

reservoir regulation, and 60 to 80 percent in regula

streams (Moffatt and others, 1990).

Hydrologic processes often are very important 

determining a stream’s water quality. Runoff from

storms can transport large quantities of pollutants,

including trace elements and organic chemicals, in

streams. In urban areas, numerous impermeable ro

and parking lots and extensive storm drainage syste

tend to route even small amounts of precipitation to

streams quickly. In contrast, agricultural and forest

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

MONTH

10,000

100,000

DAILY MEAN STREAMFLOW, IN CUBIC FEET PER SECOND

Median

25th-percentile

90th-percentile

10th-percentile

75th-percentile

EXPLANATION

Data value

Figure 2. Monthly distribution of daily mean streamflow in the Willamette River at Salem, Oregon,

1975–94 water years.
6

areas allow more opportunities for precipitation to

infiltrate into the ground rather than flow overland to a

stream. All types of landscapes, however, produce runoff in response to moderate and strong rainfall; soils

and contaminants from those landscapes are transported to streams with the runoff.

In streams, trace elements and organic compounds

may be either dissolved or associated with particulate

matter. The predominant phase depends on the contaminants chemical properties and other factors

including the concentration of suspended sediment.

The mobility and ultimate fate of pollutants that associate strongly with particulate matter depend in part on

the mobility of the particulate matter. These pollutants

may be transported, deposited, and resuspended with

or disassociated from the particles in response to different hydrologic conditions.

During the low-flow, summer period, Willamette

River Basin streams typically are characterized by low

suspended-sediment concentrations; the occurrence

and magnitude of high suspended-sediment concentrations is generally governed by precipitation runoff

(Laenen, 1995). The highest concentrations of suspended sediments, and possibly of the pollutants that

associate with those sediments, typically occur during

storms.

Land Use, Crop Types, and Pesticide Use

Approximately 70 percent of the Willamette River

Basin is forested, 22 percent is agricultural, and 5 percent is urban (Bonn and others, 1995). Land use in the

basin is generally correlated with the basin’s topographic characteristics. Elevations in the basin range

from less than 10 feet near the Columbia River to more

than 10,000 feet for the peaks of the Cascade Range.

The higher elevations have shorter summers, harsher

winters, steeper slopes, and poorer soils than the lower

elevations, making them unsuitable for agriculture.

The Willamette Valley bottom has a more hospitable

climate and better soils for agriculture, and most major

transportation hubs and industrial centers have been

located near the rivers.

The slopes and foothills of the Cascade and Coast

Ranges make up more than 50 and 20 percent of the

basin’s area, respectively. These areas are predominantly forested, with some smaller areas of agriculture

at the lower elevations and no large urban centers. The

Willamette Valley, generally considered to be the portion of the basin below an elevation of 500 feet,

encompasses the remaining 30 percent of th

area. Land use within the Willamette Valley 

but taken as a whole, it is predominantly agr

The valley is also home to all of the basin’s l

areas, including the Portland metropolitan a

lation approximately 1.5 million) at the nort

To understand what factors affect a strea

quality, it is important to consider the land u

upstream of each site of interest. The percen

forested, agricultural, and urban lands upstre

several sites representing the valley’s various 

are listed in table 2. These data show some g

patterns regarding the distribution of land us

throughout the Willamette River Basin. For 

many of the large tributaries that drain the C

Range and the Calapooya Mountains, includ

Clackamas, McKenzie, Santiam, and the Co

Middle Fork Willamette Rivers, have heavil

basins, particularly in their headwater areas. 

Range tributaries, including the Long Tom, 

mute, Tualatin, and Yamhill Rivers, originat

elevations than those draining the Cascade R

generally have larger percentages of agricul

in their basins. The Calapooia River, Puddin

and Muddy Creek Basins incorporate even l

centages of agricultural land, originating an

predominantly through agricultural areas of 

bottom.

Each site was classified as either “Fores

“Agricultural,” “Urban,” or “Mixed-use,” on 

of an areal assessment of the upstream land 

guidelines used here are the same as the pre

scheme used by the Willamette NAWQA stu

summarized in table 3. These guidelines wer

with the recognition that water-quality impa

agricultural and urban areas are typically stro

those that result from forested areas. It was a

nized that strong point or nonpoint sources u

from a sampling site could mask the influen

dominant land uses; sites were chosen to mi

these interferences.

Because agricultural practices and pestic

vary with crop type, the impact of agricultur

stream water quality often is related to the c

grown. The agricultural land in the Willame

Basin supports a wide variety of crops (table 

terms of planted acreage, grass seed, wheat, 

are by far the most important crops grown in 

(Rinehold and Witt, 1989). Other important 
7

include grains (oats, barley, corn, and hops), seed

crops (clover, sugar beets, vegetables, and flowers),

fruits and nuts (cherries, filberts, and walnuts), row

crops (beans, broccoli, peas, and others), many types

of berries, and Christmas trees.

Pesticide applications are extremely variable.

Among other considerations, the type of pesticide

used depends on the crop, and the timing of its use

depends on weather and soil conditions. To further

complicate matters, the most recently published basinwide crop and pesticide-use estimates for the State of

Oregon (Rinehold and Witt, 1989), which are based on

data from 1987, are neither current nor comprehensive. These estimates, based on surveys of pesticide

dealers and reports from commercial applicators and

county agents, represent usages associated with cultivated agriculture, forestry, rights-of-way, urban, and

miscellaneous uses. Because they are compiled for

counties rather than for drainage areas, they only p

vide a general estimate of potential pesticide loadi

to individual streams. Nevertheless, these estimate

are the best available and are needed to help interp

instream pesticide concentration data. In this repor

interpretation of pesticide data in streams is made w

the understanding that current practices are potenti

different in important ways from those during the t

of the 1987 survey.

In 1992 statewide agricultural chemical uses a

ciated with seed and specialty crops, which have

grown in importance in Oregon since the 1987 sur

were estimated by Reinhold and Jenkins (1994). O

recent reports detailing statewide pesticide use est

mates have been prepared for small fruits, tree frui

and vegetable crops. As with the seed and specialt

crop report, these data are available on a statewide

rather than a basin or countywide basis. Furthermo

the reports document surveys from successive yea

with the result that compiling a comprehensive and

quantitative estimate of updated, basinwide, annua

application practices by crop type cannot be readil

done on the basis of available literature. Nonethele

the statewide estimates do provide an important in

cation of overall changes in pesticide application p

tices. Indeed, because the Willamette Basin is the

location for much of the State’s crop production fo

Table 3. Guidelines used to classify sampling sites

according to upstream land use

Site

Classification

Percent of land upstream of

sampling site

Forest

land

Agricultural

land

Urban

land

Forested ≥ 90 ≤ 10 ≤ 10

Agricultural ≤ 50 ≥ 50 < 25

Urban ≤ 50 < 25 ≥ 50

Mixed-use < 90 < 50 < 50

Table 2. Percentages of forested, agricultural, and urban land upstream of selected locations in the Willamette River Ba

[Modified from Fegeas and others, 1983; not all locations listed here were used as sampling sites]

Site

Percentage of land use upstream of site Drainage area

(square miles) Forested Agricultural Urban

Calapooia River (at mouth) 50 47 3 371

Clackamas River (near mouth) 89 8 3 941

Coast Fork Willamette River (below Cottage Grove dam) 96 1 1 106

Long Tom River (at Monroe) 58 28 9 394

Luckiamute River (near Suver) 78 21 1 237

McKenzie River (near Coburg) 94 2 1 1,336

Middle Fork Willamette River (at Jasper) 96 1 1 1,344

Muddy Creek (near Peoria) 27 71 2 146

Pudding River (at Aurora) 37 59 4 480

Santiam River (at Jefferson) 86 11 1 1,786

Tualatin River (at West Linn) 49 38 13 714

Willamette River (at Linnton) 70 24 5 11,205

Yamhill River (at Dayton) 58 40 2 771

Zollner Creek (near Mt. Angel) 0 99 1 15
8

certain crops, many of the changes may be largely

attributed to the basin.

One example of a change in agricultural practices

is the increased prominence of nurseries, a crop which

in the 1987 estimates accounted for only 70 acres of

land in the basin, yet by 1992 had become the secondlargest crop in the State on a monetary basis, covering

approximately 24,000 acres statewide (Reinhold and

Jenkins, 1994). As nursery crops have increased in

importance, so has the use of chemicals associated

with them. For example, the use of chlorothalonil,

metolachlor, napropamide, oryzalin, pendimethalin,

and chlorpyrifos, all of which were analyzed as part of

this study, each increased by amounts ranging from

1,000 to as much as 18,000 pounds statewide on nursery crops alone. Grass seed growing, which is more

predominant in the Willamette Valley than a

place in the United States, has undergone m

changes associated with a reduction in field 

since the late 1980’s. As a result herbicide u

grass seed has changed; reductions in atrazin

nationwide trend, were offset by equivalent 

in diuron usage and registration of the herbi

flurfen to aid in removal of nuisance grasses

notable changes in chemical applications to 

speciality crops include significant increases 

statewide usage of terbufos, glyphosate, terb

cycloate, and bentazon. Meanwhile other ch

including fonofos, dinoseb, simazine, and d

have decreased in usage since 1987 (Reinho

kins, 1994).

Table 4. Acres of crops, by county, in the Willamette River Basin, Oregon, 1987

[Data are from 1987 county estimates (Rinehold and Witt, 1989); Ranks are based only upon the crops listed in this table; —, not available]

Crop5

Acres in each Willamette River Basin county Tota

acres 

Benton Clackamas Lane Linn Marion Multnomah Polk Washington Yamhill

Alfalfa hay 1,400 3,800 1,500 2,200 5,000 600 2,600 5,000 4,300 26,40

Barley 800 700 2,000 2,500 1,000 300 2,400 800 2,500 13,00

Blackberries 60 930 135 75 2,720 270 470 495 600 5,75

Broccoli 20 365 — 140 1,700 90 30 300 250 2,89

Cabbage — 345 — — 90 490 — — — 92

Cauliflower — 680 — 100 2,200 320 60 5 200 3,56

Cherries 60 95 475 65 1,500 10 2,400 480 1,500 6,58

Christmas trees 12,400 1,150 2,000 700 — 50 — — — 16,30

Clover and

vetch seed

550 2,700 600 5,850 5,000 250 4,000 22,500 8,200 49,65

Cucumbers — 695 10 10 340 340 — 500 40 1,93

Dry onions — 140 — — 2,500 — 50 500 250 3,44

Filberts 390 3,950 2,700 740 4,400 50 1,850 5,550 5,400 25,03

Grass seed 28,110 7,900 24,130 144,550 51,000 90 27,880 2,000 7,500 293,16

Green peas 1,440 455 100 130 4,800 285 — — — 7,2

Hops — 50 — — 4,500 — 800 — — 5,35

Mint 2,000 — 5,400 4,000 4,500 — 1,120 — — 17,02

Oats 3,000 4,600 3,000 5,000 7,000 500 15,600 9,900 13,600 62,20

Other hay 9,000 26,500 28,000 24,500 14,000 3,500 12,500 17,000 17,000 152,00

Pumpkins

and squash

70 480 20 75 500 350 170 45 290 2,00

Raspberries 25 2,160 70 220 300 825 55 930 130 4,7

Silage corn 800 2,300 1,500 1,200 3,800 — 1,300 3,500 2,400 16,80

Snap beans 1,515 305 1,925 1,900 12,860 60 520 770 1,500 21,35

Strawberries 90 750 145 200 2,200 330 260 2,450 500 6,92

Sugarbeet seed 1,070 140 645 540 2,130 — 200 — 145 4,87

Sweet corn 2,780 1,860 2,600 3,250 15,960 1,010 1,670 3,060 3,270 35,46

Vegetable and

flower seed

700 200 320 600 2,600 — 150 50 370 4,99

Wheat 19,500 10,000 10,500 26,000 23,000 1,800 30,600 16,000 36,000 173,40
9

Selected 1987 pesticide-use estimates for counties

in the Willamette River Basin (Rinehold and Witt,

1989) are listed in table 5. The main section of the

table lists the 30 most used pesticides in the basin,

some of which were not analyzed as part of this study.

The second section of the table lists 10 other chemicals of interest. These 10 were not among the 30 most

used pesticides in the basin, but all were detected frequently in this study; therefore, their usage estimates

are relevant. Several other pesticides, most notably

prometon, ethoprop, and tebuthiuron, also were

detected frequently, but were not included in table 5

because no usage rates were available. Note that

although the pesticide-use surveys were focussed on

agricultural areas, the estimates were not restricted to

those areas; urban areas also were represented. For

example, usage estimates for both malathion and glyphosate, chemicals used extensively in urban areas, are

much higher in predominantly urban Multnomah

County than in mostly rural Benton County.

STUDY DESIGN AND METHODS

Objectives

The streamflow and precipitation patterns of the

Willamette River Basin were critical factors in the

design of the Phase I and Phase II studies. An objective of Phase I was to examine trace-element and

organic-compound concentrations to determine

whether the concentrations are larger during summer

low flow, when river dilution is minimal and when

point sources may have their largest impact; or during

intense rainstorms. The results indicated that high

concentrations of trace elements and organic compounds were more likely during high-flow conditions.

The Phase II toxics study built on the results of

Phase I. Concentrating on the runoff and resuspension

during storms, Phase II was designed to examine relations between the timing of pesticide applications,

streamflow, and concentrations of trace metals and

organic compounds. Specific objectives included:

1. To examine the temporal variability of trace element

and pesticide concentrations and loads in a

sequence of major periods of storm runoff following pesticide application.

2. To relate concentrations and, where relevant, instantaneous loads of trace elements and pesticides to

land use activities, pesticide applications, and

streamflow conditions.

1. To measure the partitioning of selected trace ele

ments and hydrophobic pesticides between th

dissolved and suspended phases for selected

samples.

The locations of sites sampled during Phases I 

II are shown in figure 3. Selected sites were sample

high flow in the spring shortly after pesticides were

applied, and in the fall during the first major storm

following summer low-flows. In addition, the fall s

pling included several samples taken during the ris

and fall of successive storm hydrographs.

Sampling Locations, Dates, and

Constituents

Phase I sampling was done at only 11 sites

(table 6); however, the number of constituents a

lyzed was extensive. In addition to both filtered

and unfiltered water samples, samples of suspended and bed sediment were also collected.

These samples were analyzed for a wide range 

toxic constituents, including trace elements, org

nochlorine and organophosphorus compounds

(OCs and OPs), volatile organic compounds

(VOCs), semivolatile organic compounds, poly

chlorinated dibenzo-p-dioxins, and polychlorinated dibenzofurans. Filtered water samples we

also analyzed for a set of 40 to 90 pesticides.

Ancillary data included discharge, suspendedsediment concentrations, water hardness, and

organic carbon and nutrient concentrations. The

Phase I sites and analyses discussed in this repo

are listed in table 6.

Phase II sampling was performed at 32 sites du

ing the spring of 1994 and at 16 sites during the fal

1994 (tables 7 and 8, respectively). Several of the f

sites were sampled multiple times. Samples collect

during Phase II were analyzed for organochlorine

compounds in unfiltered water, triazine herbicides 

filtered water, and a suite of 89 pesticides in filtere

water. On selected samples, additional analyses we

performed, including VOCs in unfiltered water, tra

elements in unfiltered and (or) filtered water, and O

in both filtered water and suspended sediment. Anc

lary data, including discharge, suspended-sediment

concentration, water hardness, and organic carbon 

selected nutrient concentrations were also collected
10

Table 5. Annual usage rates of chemicals to control weeds and pests, by county, in the Willamette River Bas

1987

[Data are from 1987 county pesticide use estimates (Rinehold and Witt, 1989); *, analyzed as part of Phases I and II of the Willamette 

Water Quality Study; —, not available; 2,4-D, 2,4-dichlorophenoxyacetic acid; EPTC, S-ethyl dipropylthiocarbamate; MCPA, (4-chlor

methyl)phenoxyacetic acid; DCPA, dimethyl tetrachloroterephthalate]

Compound

Usage rate in each Willamette River Basin county (pounds/year) Total usage

(pounds/year) 

Benton Clackamas Lane Linn Marion Multnomah Polk Washington Yamhill

Chemicals with the 30 highest usage rates

2,4-D* 19,000 5,700 47,000 79,000 57,000 45,000 28,000 13,000 37,000 330,700 

Alachlor* 7,300 3,700 3,900 8,300 30,000 440 3,000 2,400 4,500 63,540 

Atrazine* 35,000 12,000 34,000 140,000 110,000 17,000 39,000 6,400 16,000 409,400 

Benomyl 2,500 1,000 2,900 4,500 9,500 3,000 2,200 1,500 10,000 37,100 

Calcium polysulfide 1,800 100,000 23,000 2,100 53,000 60,000 52,000 72,000 38,000 401,900 

Captan 960 3,400 12,000 1,700 9,000 9,000 5,400 6,200 4,300 51,960 

Carbaryl* 3,500 17,000 18,000 4,500 26,000 20,000 6,800 6,700 17,000 119,500 

Chlorothalonil* 25,000 1,300 6,400 21,000 26,000 8,300 14,000 4,500 5,500 112,000 

Chlorpyrifos* 8,100 2,900 13,000 25,000 28,000 30,000 4,300 610 8,800 120,710 

Copper* 3,800 25,000 5,300 7,200 90,000 23,000 56,000 13,000 93,000 316,300 

Diazinon* 2,000 4,900 15,000 5,500 23,000 46,000 12,000 2,000 12,000 122,400 

Dicamba* 4,000 530 5,500 21,000 16,000 2,500 16,000 1,800 4,900 72,230 

Dichlobenil* 580 3,000 3,500 1,600 7,500 17,000 6,000 2,300 4,600 46,080 

Dichloropropene — 13,000 — — 2,500 11,000 — 29,000 — 55,500 

Diclofop 13,000 580 9,000 16,000 13,000 1,800 19,000 15,000 21,000 108,380 

Dinoseb* 15,000 9,400 9,400 16,000 40,000 4,000 4,600 1,900 8,500 108,800 

Diuron* 44,000 7,500 36,000 160,000 82,000 18,000 100,000 47,000 58,000 552,500 

EPTC* 14,000 2,400 8,000 17,000 25,000 1,600 1,800 4,300 4,500 78,600 

Ethofumesate 7,500 200 6,000 45,000 7,500 — 2,600 50 190 69,040 

Fonofos* 3,600 6,300 20,000 11,000 56,000 2,600 6,200 2,100 6,300 114,100 

Glyphosate 4,700 4,700 19,000 17,000 27,000 61,000 7,500 8,900 8,500 158,300 

MCPA* 12,000 2,500 12,000 19,000 24,000 1,400 30,000 13,000 20,000 133,900 

Malathion* 360 2,100 350 370 5,600 50,000 2,600 3,400 6,900 71,680 

Maneb 32,000 1,400 41,000 80,000 100,000 5,000 4,000 9,000 6,800 279,200 

Metaldehyde 400 2,900 3,900 340 27,000 20,000 4,000 1,600 20,000 80,140 

Metolachlor* 12,000 1,400 2,600 9,500 12,000 350 1,200 1,900 1,500 42,450 

Napropamide* 890 12,000 3,000 1,600 16,000 15,000 5,800 14,000 6,500 74,790 

Oil 1,300 23,000 40,000 1,500 120,000 27,000 16,000 17,000 74,000 319,800 

Simazine* 7,700 5,400 18,000 40,000 42,000 23,000 15,000 11,000 4,500 166,600 

Sulfur 4,000 1,700 12,000 5,000 61,000 3,500 96,000 8,200 49,000 240,400 

Additional chemicals of interest—basinwide usage rates ranked lower than 30th

Carbofuran* — 1,400 1,200 — 760 1,300 180 5,400 500 10,740 

Cycloate* 4,300 140 2,700 2,200 250 42 540 — 1,700 11,872 

DCPA* 45 — — 320 — — — — — 365 

Hexazinone* 5,700 1,000 530 1,400 570 2,800 4,000 1,400 1,600 19,000 

Lindane* — — — — 110 — 230 — 75 415 

Metribuzin* — 610 — — 710 300 370 580 1,000 3,570 

Pronamide* 1,300 2,800 970 2,100 6,300 1,100 3,700 1,400 2,100 21,770 

Terbacil* 2,100 160 6,000 6,000 3,700 160 750 300 — 19,170 

Triclopyr* 2,800 1,200 2,400 3,400 1,100 6,400 240 3,300 140 20,980 

Trifluralin* 2,800 280 2,300 2,300 13,000 350 590 690 1,100 23,410 
11

Figure 3. Sampling sites for Phases I and II of the Willamette River Basin Water Quality Study, Oregon, 1992–94.

(Index numbers on the map refer to specific sites listed in tables 6, 7, and 8.)
12

complete list of the constituents analyzed during

Phases I and II was documented by Harrison and others (1995).

In this report, the term “DDX compounds” is used

to refer to undefined combinations of individual species of DDT or its metabolites, DDE or DDD, whereas

“ΣDDX” refers to the sum of their concentrations

(DDT + DDD + DDE). From a regulatory standpoint,

DDT, DDE, and DDD are often referred to either

interchangeably (to indicate presence of DDX compounds) or in summation (to indicate a total concentration). When tallying ΣDDX, individual concentrations

of DDT, DDD, or DDE were set to zero if the individual species was not detected. DDX compounds and

ΣDDX generally refer to just one sampling medium

(unfiltered or filtered water or suspended sediment)

unless otherwise noted.

Methods

Data for this report were published by Harrison

and others (1995). These data are from the USGS’s

National Water Information Storage system 

and were current as of May 1995. Owing to 

updates to NWIS from the USGS National W

Quality Laboratory (NWQL), data in NWIS 

ject to change at a future date. A detailed de

of the methods used for collecting and proce

samples (both in the field and in the laborato

cleaning equipment was provided by Harris

others (1995). Sampling methods used in th

conformed to standard USGS procedures ex

where otherwise noted. For safety reasons, w

storm drains and manholes was collected as 

ples. Samples were analyzed at the NWQL i

Colorado.

Quality Assurance

The NWQL maintains an extensive and 

ous quality-assurance/quality-control progra

addition, the USGS Branch of Technical Dev

and Quality Systems routinely administers n

laboratory intercomparison studies for analy

Table 6. Sampling plan for data used in this report and collected during Phase I of the Willamette River Basin Wa

Study, Oregon, 1992–93

[Sites are listed in downstream order by site type and can be located in figure 3 by map index number; Basic, basic analyses, including flow, w

temperature, specific conductance, pH, dissolved oxygen, suspended sediment, and dissolved and suspended organic carbon; UW, unfiltered 

filtered water; SS, suspended sediment; GCMS, analysis of filtered water by gas chromatography/mass spectrometry; HPLC, analysis of filter

high-performance liquid chromatography; OC, organochlorine compounds; VOCs, volatile organic compounds; for a list of specific constitue

Harrison and others, 1995]

Map

index

number

Station name Station number Date Basic

Organic compounds

Trace elements Pesticides OC VO

UW FW SS GCMS HPLC UW FW SS U

Urban sites

3 A-3 Channel at Wallis and 5th St., Eugene 440313123091100 920416 X X X X 

921016 X X X X X X 

921029 X X X X X

38 Beaverton Cr at 216th Ave. nr Orenco 453115122535500 930331 X X X X X X X 

39 Fanno Cr at Durham 14206950 930301 X X X X X X X 

930722 X X X X X X 

44 Johnson Cr at Milwaukie 14211550 930314 X X X X X X X 

Mixed-use sites

10 Willamette R nr Corvallis 443207123145500 930824 X X X X X X 

49 Willamette R at Linnton 453547122463000 920418 X X X X

921026 X X X X X 

Agricultural sites

11 Muddy Cr nr Peoria 443138123120901 930824 X X X X X X 

27 Palmer Cr at Dayton 451309123041501 930907 X X X X X X 

28 Yamhill R at Dayton 451320123041100 930907 X X X X

32 Zollner Cr nr Mt Angel 14201300 930601 X X X X X X X X 

930727 X X X X X X 

33 Pudding R at Aurora 14202000 930427 X X X X X X X X 
13

Table 7. Sampling plan for Phase II of the Willamette River Basin Water Quality Study, Oregon, spring 1994

[Sites are listed in downstream order and can be located in figure 3 by map index number; Basic, basic analyses, including flow, water temperatu

specific conductance, pH, dissolved oxygen, suspended sediment, and dissolved and suspended organic carbon; UW, unfiltered water; FW, filtere

water; Pesticides, selected pesticides in filtered water by solid phase extraction and gas chromatography/mass spectrometry or high-performance

liquid chromatography; Triazines, low-level triazine herbicides in filtered water; OCs-UW, organochlorine compounds in unfiltered water; VOCs

volatile organic compounds; for a list of specific constituents see Harrison and others, 1995]

Map

index

number

Station name Station number Date Basic

Trace elements Organic compounds

UW FW Pesticides Triazines OCs-UW VOCs

Urban sites

4 Urban outfall at Greenway Bicycle Bridge

at Eugene

440402123063900 940613 X X X X X X

37 Bronson Cr at 185th Ave nr Aloha 14206298 940527 X X X X X

39 Fanno Cr at Durham 14206950 940524 X X X

940616 X X

45 Urban runoff at Harbor Way at Portland 453043122402200 940617 X X X X X X

47 Interstate 84 runoff at Portland 453154122394200 940531 X X X X X X X

Forested sites

1 Coast Fork Willamette R bl Big R nr London 433548123040600 940520 X X X X X

5 Mack Cr nr Blue River 441310122095801 940527 X X X X

12 Rock Cr ab Griffith Cr nr Philomath 443045123273000 940518 X X X X

Mixed-use sites

2 Coast Fork Willamette R at Seavey Loop

Rd nr Eugene

440045122585600 940519 X X X X X

7 McKenzie R nr Eugene 440707123041300 940519 X X X X

13 Marys R at Corvallis 443321123155201 940518 X X X X X

17 Luckiamute R nr Buena Vista 444349123094000 940516 X X X X

19 Santiam R at Jefferson 14189000 940517 X X X X

30 Willamette R at Hwy 219 nr Newberg 451602122564400 940531 X X X X X X

34 Molalla R nr Canby 451603122423301 940525 X X X X

40 Tualatin R at West Linn 14207500 940525 X X X X X

46 Willamette R at Portland harbor 14211720 940510 X X X

940614 X X

48 Willamette R ab St John’s Bridge at Portland 14211805 940523 X X X X X

Agricultural sites

8 Long Tom R at Bundy Bridge nr Monroe 442223123153703 940519 X X X

9 Lake Cr at Pine Grove Dr nr Harrisburg 442413123122500 940519 X X X

14 Calapooia R at Albany 14173500 940526 X X X

11 Muddy Cr nr Peoria 443138123120901 940526 X X X

940603 X X X

940620 X X X

18 Thomas Cr at Kelly Rd nr Jefferson 444123122562200 940516 X X X X

22 Rickreall Cr nr mouth nr Salem 445547123065400 940526 X X X X

24 Mill Cr at Delaney Rd nr Turner 445037122573800 940614 X X X X X

25 S. Yamhill R at McMinnville 14194150 940517 X X X X X

26 N. Yamhill R nr McMinnville 451355123093600 940517 X X X X

31 Champoeg Cr bl Mission Cr nr Butteville 451502122524700 940526 X X X X

32 Zollner Cr nr Mt Angel 14201300 940525 X X

940613 X X

33 Pudding R at Aurora 14202000 940412 X X

940525 X X

940615 X X

35 Dairy Cr at Rte 8 nr Hillsboro 14206200 940527 X X X X

42 Johnson Cr at Palmblad Rd nr Gresham 452823122240900 940524 X X X X
14

Table 8. Sampling plan for Phase II of the Willamette River Basin Water Quality Study, Oregon, fall 1994

[Sites are listed in downstream order by site type and can be located in figure 3 by map index number; Basic, basic analyses, including 

water temperature, specific conductance, pH, dissolved oxygen, suspended sediment, and dissolved- and suspended-organic carbon; UW

unfiltered water; FW, filtered water; SS, suspended sediment; Pesticides, selected pesticides in filtered water by solid phase extraction a

gas chromatography/mass spectrometry or high-performance liquid chromatography; Triazines, low-level triazine herbicides in filtered 

OC, organochlorine; VOCs, volatile organic compounds; for a list of specific constituents see Harrison and others, 1995]

Map

index

number

Station name Station number Date Basic Trace elements

Organic compounds

Pesticides Triazines OC compounds 

UW FW UW FW S

Urban sites

23 Pringle Cr at Bush Park at Salem 14190970 941123 X X X X X X

941130 X X X X X

941130 X X X X X

37 Bronson Cr at 185th Ave nr Aloha 14206298 941123 X X X X X X 

39 Fanno Cr at Durham. 14206950 941027 X X X X X

941130 X X

47 Interstate 84 runoff at Portland 453154122394200 941108 X X X X X X X X 

941108 X X X X X

941130 X X X X X 

941130 X X X X X

941202 X X X X X

Mixed-use sites

40 Tualatin R at West Linn 14207500 941028 X X X X X

941205 X X

46 Willamette R at Portland harbor 14211720 941025 X X X

941029 X X X X X X X X

941103 X X X X X

941202 X X X

Agricultural sites

8 Long Tom R at Bundy Bridge

nr Monroe

442223123153703 941101 X X X X

11 Muddy Cr nr Peoria 443138123120901 941102 X X X X X X

941106 X X X X X X

941109 X X X X

14 Calapooia R at Albany 14173500 941101 X X X X

24 Mill Cr at Delaney Rd nr Turner 445037122573800 941031 X X X X

941104 X X X X X X

941104 X X X X

25 S. Yamhill R at McMinnville 14194150 941102 X X X X

31 Champoeg Cr bl Mission Cr

nr Butteville

451502122524700 941031 X X X X

32 Zollner Cr nr Mount Angel 14201300 941028 X X X X

941128 X X

33 Pudding R at Aurora 14202000 941028 X X X X X X

941029 X X X X

941109 X X X X

941129 X X

35 Dairy Cr at Rte 8 nr Hillsboro 14206200 941201 X X X X X

42 Johnson Cr at Palmblad Rd

nr Gresham

452823122240900 941027 X X X X X X

941028 X X X X X X

941101 X X X X

941103 X X X X X

941123 X X X X
15

inorganic constituents to assess the performance of

USGS and other laboratories using selected standard

reference samples. The performance of the NWQL in

these intercomparisons for the period of this study has

been assessed and documented (laboratory #1 in Long

and Farrar, 1994, 1995).

Quality-control samples accounted for approximately 15 percent of the Phase I and II samples sent to

the NWQL; these samples were used to assess the

quality of the data collected in this study. Several types

of quality-control samples were submitted: laboratory,

field, and equipment blanks were used to assess the

potential for contamination; split samples were analyzed to estimate precision; spike solutions in nativewater samples were used to test both accuracy and precision (when performed in duplicate). Specific results

from the quality-control program were documented by

Harrison and others (1995). Because of the variable

nature of spike-recovery tests, use of quality assurance

results to normalize native-water concentrations is not

recommended. In this report data are presented as they

were reported by the laboratory, with interpretations

regarding quality control provided where appropriate.

In general, the results of spike-recovery tests, blanks,

and duplicate spike recoveries for organic compounds

in native-water mixtures were quite good. The balance

of this section describes a few of the quality-control

results that are relevant to the interpretation of the

data.

The lower limit of the NWQL’s analytical capabilities are reported by one of two methods. The minimum reporting level (MRL) is the smallest measured

concentration of a constituent that may be reliably

reported using a given analytical method. For methods

that use MRLs, concentrations that are less than the

MRL are censored, and the data are reported as less

than the value of the MRL. The method detection limit

(MDL) is the minimum concentration of a substance

that can be identified, measured, and reported with

99-percent confidence as being greater than zero

(Timme, 1994). For methods that use MDLs, concentrations may be reported that are less than the MDL for

a given analyte; however, the chance of a false-positive

detection for these results is greater than one percent.

By far, most of the data included in this report were

determined by methods that use MRLs. The exceptions are pesticides in filtered water analyzed under the

NWQL’s “schedule 2010” and under the custom analytical schedule “LC8015” (see below).

Replicate analyses for the trace-element sampl

generally indicated a high level of precision. Phase 

stream samples submitted to the NWQL for duplic

analysis had identical concentrations for 5 of 7 trac

elements in unfiltered water and 10 of 17 trace elements in filtered water. Of the remaining elements, 

relative differences between the replicate samples i

unfiltered water were 3.4 and 5.3 percent for chromium and lead, respectively, and in filtered water

ranged from 1.8 to 67 percent. Four of the differen

in filtered-water results were greater than 10 percen

however, each of these differences was at relatively

low concentrations (less than 10 μg/L [micrograms 

liter]), a concentration range in which the variabilit

typically higher. Accuracy was assessed through th

USGS’ internal quality assurance procedures, whic

indicate that during the Phase II sampling period, 3

15, 7, and 5 percent of the dissolved cadmium, copp

nickel, and zinc quality-assurance samples, respectively, were outside of control limits (greater than

2 standard deviations from the mean sample conce

tration). All other dissolved trace elements were

within control limits at all times.

A field-blank sample from the Phase II spring

dataset indicated a possible unfiltered-water contam

nation of 0.2, 3, 2, and 10 μg/L for cadmium, copp

nickel, and zinc, respectively. In contrast, median

detected springtime concentrations for these compounds were 4, 1, 2, and 245 μg/L, respectively. Up 

10 samples were potentially affected, although for

cadmium and zinc only two of the springtime samp

had detections in unfiltered water, at concentration

that were much higher than the level of contaminati

In this report, unfiltered-water detections of copper 

samples) and nickel (4 samples) from spring of 199

that were equal to or less than the observed levels o

contamination were eliminated from the data set. T

contamination problem was subsequently eliminate

through equipment modification; a field-blank sam

from the Phase II fall sampling indicated no contam

nation of trace elements in unfiltered or filtered wa

Rather than customize its methods for every an

lyte of possible interest, the NWQL commonly dev

ops procedures that are suitable for entire groups o

analytes with similar chemical properties. The use 

these “schedules” means that, if more than one sch

ule is requested, the concentration of a particular a

lyte might be determined more than once for each

sample. Indeed, several organic compounds are

included in more than one schedule used during th
16

Willamette Study. This is particularly true of the

triazine herbicides, many of which were included

in both schedule “2010” and in a custom schedule

(“LC8015”) that was used only for the low-level analysis of triazine herbicides. In both schedules, a water

sample is extracted onto a cartridge packed with a carbon-based adsorbent, eluted at the NWQL with a solvent, and analyzed by gas chromatography/mass

spectrometry (GC/MS) (Sandstrom and others, 1994;

Zaugg and others, 1995). A comparison of results for

common constituents in this study, however, indicated

that the LC8015 method produced consistently poorer

recoveries than the schedule 2010 method (Harrison

and others, 1995). Because both schedules were used

for each sample collected, and because the precision

and accuracy of the schedule 2010 data were consistently better, results from schedule 2010 were used

whenever possible. Results for a few constituents were

only available as part of the LC8015 schedule; data for

those constituents, therefore, were the only results

from schedule LC8015 that were used in this report

(Appendix 5).

Analogous to the overlap of constituents between

schedules 2010 and LC8015, three particular compounds (carbofuran, carbaryl, and linuron) were

included in both schedules 2010 and 2051. The latter

schedule analyzes 41 compounds from a filtered water

sample using solid-phase extraction and high-performance liquid chromatography (HPLC). Spike recoveries for the 2051 method were highly variable and,

where comparisons could be made, lower than those

from schedule 2010. For carbofuran, carbaryl, and

linuron, the schedule 2010 results were used, and the

schedule 2051 results were used generally for reference purposes only.

For the purposes of this report, data from schedule 2051 are considered to be primarily qualitative.

Quality-assurance data collected from a variety of

programs within the USGS have indicated that quantitative values for analytes in this schedule have a high

degree of uncertainty. Percent spike-recovery data

show relatively low and variable precision for many

compounds. On the basis of limited samples, precision

may be particularly variable at low ambient concentrations. However, no incidences of false-positive

results have been observed. Therefore when these constituents are detected in a sample, they are considered

to be present. For example, one such pesticide that was

consistently detected was diuron. Recoveries for diuron samples spiked at approximately 1 μg/L ranged

from 27 to 83 percent (median 51.6 percent)

less, one quarter of the native-water concent

recorded for diuron were less than 0.11 μg/L

these results indicated that diuron was actual

in these samples, probably at low concentra

exact magnitude of their concentrations is u

Quality-assurance results for the orga

rine compounds (OCs) in unfiltered-wate

were mixed. Three different native-water 

were split for duplicate analyses; howeve

were not detected in any of these sample

respective duplicates. Duplicate spike an

were performed on an additional sample, 

the spike recoveries were relatively low (

from 28 to 67 percent for the 10 compou

spiked) but repeatable. There was no evid

contamination in blank or split samples. 

son of results of unfiltered-water analysis 

with the sum of OCs in filtered water and 

suspended sediment indicated that the un

water analysis usually underestimated the 

tration of ΣDDX in the filtered and suspe

phases. The largest discrepancy occurred 

one sample from Johnson Creek, which h

unfiltered-water concentration of ΣDDX 

μg/L, whereas the ΣDDX concentration i

tered and suspended phases was 0.064 μg

differences are most likely due to the hig

tioning of chlorinated organic compound

pended sediment, such that a greater mas

analyte is usually available for analysis i

pended phase compared to a unfiltered-w

ple. In the limited number of suspended a

filtered phase samples, no other OCs were 

so additional comparison is not possible.

RESULTS

Hydrologic Conditions

Because precipitation and runoff influen

water quality characteristics of samples coll

this study, the hydrologic conditions must b

ered along with chemical data. Daily rainfal

in Portland and Eugene for the Phase II stud

are shown in figure 4. Although rainfall in P

and Eugene does not completely represent r

other parts of the Willamette River Basin, th
17

indicate the general timing of storms and their relative

strength.

Although one intent of Phase II was to sample during “high flow” in the spring following the application

of pesticides, late-spring rains were unusually light

and infrequent in 1994 (fig. 4). Average springtime

(April to June) precipitation in Portland and Eugene

from 1961–90 was 5.9 and 6.7 inches, respectively,

whereas springtime rainfall in 1994 was 3.2 and 4.7

inches, respectively (Oregon Climate Service, 1996).

On the basis of discussions with personnel from

ODEQ and the WRTASC, it was decided that the sampling program would proceed at most sites after May

15, regardless of flow conditions, in the hopes that

streamflows would not have receded so far that they

would qualify as “low flow.” Several storms contributed small amounts of rainfall, most notably on May

14 and June 5, 1994, but they did not produce basinwide high flow conditions.

In contrast to spring conditions, rainfall during the

fall of 1994 was much more substantial and more

evenly distributed throughout the basin. Average fall

(October to December) precipitation in Portland and

Eugene from 1961–90 was 14.1 and 20.3 inches,

respectively; however, fall rainfall in 1994 was 19.2

and 23.2 inches at these two locations, respectively

(Oregon Climate Service, 1996). Sampling commenced on October 27th (table 8) after the large storm

on October 25–27 increased flows in rapidly responding small urban streams as well as in larger and slower

responding streams draining agricultural and mixeduse basins. Sampling was conducted throughout October and November as rainfall continued to be near or

above average. The final series of storms that were

sampled occurred at the end of November and lasted

through December 5, 1994 (fig. 4, table 8).

Because of these rainfall patterns, Phase II sampling at most sites occurred during relatively low-flow

conditions in spring and high-flow conditions during

fall. Figure 5 illustrates the hydrologic conditions

encountered during the Phase II sampling periods at

four gaged sites, including an urban, an agricultural,

and two mixed-use sites. Because streamflow was not

gaged at the sampling site on Johnson Creek at Palmblad Road, streamflow records from the nearest gaged

site downstream (Johnson Creek at Sycamore) were

used to indicate the relative timing of sampling. The

fall samplings for several sites occurred during streamflows that are exceeded by only 10 percent of the

recorded daily mean flows; springtime samplings

occurred at streamflows that are exceeded by about 

percent of the daily mean flows. As a result, the

detected concentrations and the frequency of detect

of trace elements and organic constituents during t

spring sampling may not accurately reflect normal 

off conditions or land-use activity for typical spring

conditions. Furthermore, data from the Phase II fal

sampling may be similar to those which might hav

been found during spring runoff in years with more

normal rainfall patterns because of the dry anteced

conditions, from April to October, after many poten

pesticide-applications periods.

Trace Elements

Summary statistics for detections of trace elem

from all Phase I and Phase II samplings are shown 

Appendix 1. Trace elements were primarily sample

urban sites, particularly during Phase II. Because o

objective of these studies was to sample at sites wh

detections of trace elements or organic compounds

were expected, sites were not selected at random.

Finally, some sites were sampled more often than o

sites. For these reasons, the analytical results repre

episodic conditions for specific sites but may not a

rately reflect basinwide concentrations of the const

ents.

Exceedances of Water-Quality Criteria

Water-quality criteria were specified by ODEQ

constituent concentrations in water were compared 

Oregon’s freshwater aquatic-life criteria for acute

(ATC) and chronic (CTC) toxicity and criteria for t

protection of human health for water and fish inges

(HHP), at a cancer risk level of 1 in 1 million (Ore

Administrative Rules, Chapter 340, Division 41, 19

These criteria are summarized in Appendix 2. Som

caution must be used in applying the criteria to dat

from Phases I and II, which represent instantaneou

values; some toxicity criteria for acute and chronic

toxicity are time dependent. Acute toxicity criteria

are based on either instantaneous concentrations or

1-hour-average concentrations that must not be exc

ed more than once every 3 years, depending on the 

stituent. Likewise, chronic toxicity criteria are not t

exceeded for more than 24 hours or 4 days once eve

years, depending on the constituent. Much of the

data are from filtered water samples, whereas the s

dards generally are based on unfiltered-water conce
18

Figure 4. Daily precipitation at Portland and Eugene during Phase II of the Willamette River Basin Water Quality Study, Oregon, 1994

0

4.0

1.02.03.0

5 10 15 20 25 31 5 10 15 20 25 30 5 10 15 

October November Decemb

1994

5 10 15 20 25 31 5 10 15 20 25

May June

1994

0

4.0

1.02.03.0

EXPLANATION

Eugene, ORPortland, OR

PRECIPITATION, IN INCHES

SPRING SAMPLING (5/16/94-6/17/94)

FALL SAMPLING (10/25/94-12/02/94)
19

Figure 5. Percent of time daily mean streamflows were exceeded and instantaneous streamflows during sampling at

four sites during Phase II of the Willamette River Basin Water Quality Study, Oregon, 1994.

0.1 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99

1

1,000

2

3

4

5

7

10

20

30

40

50

70

100

200

300

400

500

700

0.1 1 2 5 10 20 30 40 50 60 70 80 90 95 98 99

0.1

1,000

0.2

0.5

1

2

5

10

20

50

100

200

500

1 2 5 10 20 30 40 50 60 70 80 90 95 98 99

10

10,000

20

30

40

50

70

100

200

300

400

500

700

1,000

2,000

3,000

4,000

5,000

7,000

1 2 5 10 20 30 40 50 60 70 80 90 95 98 99 1,000

1,000,000

2,000

3,000

4,000

5,000

7,000

10,000

20,000

30,000

40,000

50,000

70,000

100,000

200,000

300,000

400,000

500,000

700,000

EXPLANATION

Exceedance curve for daily mean streamflow

Instantaneous streamflow during fall sampling

Instantaneous streamflow during spring sampling

PERCENT OF TIME INDICATED DAILY MEAN STREAMFLOW WAS EQUALED OR EXCEEDED

STREAMFLOW, IN CUBIC FEET PER SECOND

Fanno Creek at Durham (urban site)

1/1/92-12/31/94

Johnson Creek at Sycamore (agricultural site)

10/1/50-9/30/94

Tualatin River at West Linn (mixed-use site)

10/1/75-9/30/94

Willamette River at Portland (mixed-use site)

10/1/50-9/30/94
20

trations. Many of the criterion values are lower than

either conventional analytical detection limits or the

relatively low detection limits achieved in this study.

Consequently, some analytical results, in cases where

the analytes were not detected at concentrations higher

than their respective criteria, are considered inconclusive relative to criterion exceedances. These instances

are noted in the appropriate tables. These aspects were

not designed into the sampling plans because the large

amount of additional sampling and laboratory analyses

required to rigorously determine compliance with criteria was beyond the scope of the project.

Exceedances of criteria for trace-element concentrations in water are shown in table 9. Exceedances are

noted if a concentration exceeded an indicated criterion on any one sampling occasion. Because the number of samples at each station varied, no attempt was

made to document the number of times a given criterion was exceeded at a particular site. Codes in the

table indicate the specific criterion (ACT, CTC, or

HHP) for which the observed concentrations were

either inconclusive or in exceedance. Exceedances for

trace elements in bed-sediment samples (Phase I) are

documented elsewhere (Tetra Tech, Inc., 1995).

Analyses for criteria exceedances for arsenic and

mercury were inconclusive at many sites because the

criteria for those trace elements are below the MRLs

used (1 and 0.1 μg/L, respectively). No ATC or CTC

has been defined by the State of Oregon for arsenic;

however, the HHP is very low (0.0022 μg/L). For this

reason, if arsenic was detected in any sample, the HHP

was exceeded; otherwise, the results were inconclusive. For mercury, the ATC, CTC, and HHP values are

2.4, 0.012, and 0.144 μg/L, respectively. Mercury was

detected in only one sample (A-3 Channel in Eugene,

0.1 mg/L), exceeding the CTC value; results from all

other samples were inconclusive with respect to that

criterion.

Water-quality criteria for cadmium, copper, lead,

nickel, silver, and zinc are dependent on the hardness

of the water. When hardness is low (median hardness

for urban samples from Phases I and II was 46 mg/L

[milligrams per liter]), the criterion may drop below

the MRL, yielding inconclusive results. Consider the

following example: A sample of filtered water from

the urban outfall in Eugene had a cadmium concentration of less than 1 μg/L and a hardness of 73 mg/L as

CaCO3 (calcium carbonate). Using the equation from

Appendix 2, the CTC for cadmium is 0.88 μg/L,

which is less than the MRL of 1 μg/L. Because the

actual concentration may have been greater 

than 0.88 μg/L, the result is inconclusive for 

contrast, because the ATC for the same sam

calculated to be 2.75 μg/L, which is greater 

concentration measured, the ATC was not ex

Similar arguments apply for the other hardn

dent results listed in table 9.

The criteria for trace elements in water w

exceeded in a higher percentage of samples 

urban sites than from agricultural or mixed-

Copper, lead, and zinc exceeded either the A

CTC at five to six of the nine urban sites sam

Among all sites, the most exceedances were 

Samples from A-3 Channel at Wallis an

Street in Eugene exceeded criteria for six of 

elements, and were inconclusive for cadmiu

ver due to low hardness. Samples from Fann

Durham Road exceeded criteria for four of t

constituents, and were inconclusive for cadm

cury, and silver. Of the sites draining predom

agricultural areas, Dairy Creek near Route 8 

boro, Pudding River at Aurora, and Zollner C

Mount Angel were the only sites at which ex

were recorded. At these two sites, arsenic an

concentrations were higher than the HHP an

CTC, respectively. Mixed-use sites having c

trations of trace elements higher than their r

criteria included the Tualatin River at West L

and the Willamette River at Portland (coppe

Relation to Land Use

Figure 6 shows all detected unfiltered-w

concentrations of arsenic, copper, chromium

nickel, and zinc at urban, agricultural, mixed

forested sites during Phases I and II. Despite 

ent biases in the data set due to the variable 

of samples collected at the different site typ

sites typically had higher concentrations of t

elements than did the other site types. In par

concentrations of copper, lead, and zinc, wh

often associated with urban runoff, were con

higher at the urban sites. The most frequentl

trace element at agricultural and mixed-use 

copper.

Three of the urban sites were storm drai

holes (an urban outfall to the Willamette Riv

Eugene, a manhole accessing storm drainag

parts of downtown Portland at Southwest Ha

and a manhole accessing drainage from Inte

at Southeast 3rd Avenue in Portland [I-84 ru
21

Table 9. Exceedances of State of Oregon criteria for trace elements in unfiltered and filtered water for streams

sampled during Phases I and II of the Willamette River Basin Water Quality Study, Oregon, 1992–94

[Sites are listed in downstream order by site type; water quality criteria are from Oregon Administrative Rules, Chapter 340, Division 41, 1994; trace

elements for which no criteria exist, and sites for which no trace-element samples were collected, were excluded from this table; chromium was assum

be entirely in the hexavalent state; freshwater criteria for acute and chronic toxicity for cadmium, copper, lead, nickel, silver, and zinc were calculated 

the basis of measured hardness; 1, freshwater aquatic life criterion for acute toxicity; 2, freshwater aquatic life criterion for chronic toxicity; 3, criterio

protection of human health for water and fish ingestion (carcinogenic risk level of 1 in 1million); *, not detected, but results inconclusive because mini

reporting level (MRL) was larger than criterion for acute toxicity; †, not detected, but results inconclusive because MRL was larger than criterion for

chronic toxicity; ‡, not detected, but results inconclusive because MRL was larger than the human health criterion; shaded areas, not sampled; blank

areas, sampled with no exceedance detected]

Site

Criteria Exceeded

Arsenic Cadmium Chromium Copper Lead Mercury Nickel Silver Zin

Urban sites

Urban outfall at Greenway Bicycle Bridge at

Eugene

3† † †

A-3 Channel at Wallis & 5th St., Eugene 3 *,† 1,2 1,2 1,2 2 *,† 1,

Pringle Creek at Bush Park at Salem ‡ *,† 1,2 1,2 *,† 1,

Beaverton Creek at 216th Ave. near Orenco ‡ † †

Bronson Creek at 185th Ave. near Aloha ‡ † †

Fanno Creek at Durham 3 *,† 2 2 † † 1,

Johnson Creek at Milwaukie ‡ † 2 † †

Urban runoff at Harbor Way at Portland 3 1,2 1,2 1,2 *,† 1,

Interstate-84 runoff at Portland 3 1,2 2 1,2 1,2,3 *,† 1,

Agricultural sites

Muddy Creek near Peoria ‡ † † †

Mill Creek at Delaney Rd. near Turner

South Yamhill River at McMinnville † †

Palmer Creek at Dayton ‡ † † *,†

Zollner Creek near Mount Angel 3 † †

Pudding River at Aurora ‡ *,† 2 † *,†

Dairy Creek at Rte. 8 near Hillsboro 3 † 2

Johnson Creek at Palmblad Rd. near Gresham

Mixed-use sites

Coast Fork Willamette River at Seavey Loop Rd. *,† †

Marys River at Corvallis † †

Willamette River below Corvallis WTP ‡ *,† † † *,†

Willamette River upstream Hwy. 219 at Newberg ‡ *,† † *,†

Tualatin River at West Linn † 2

Willamette River at Portland ‡ *,† 1,2 † *,†

Willamette River above St. Johns Bridge at Portland

† †

Willamette River at Linnton ‡ † *,†

Forested site

Coast Fork Willamette River below Big River

near London

*,† † †
22

Figure 6. Concentrations of selected trace elements in unfiltered water detected at different site types during Pha

of the Willamette River Basin Water Quality Study, Oregon, 1992–94. (Lower minimum reporting levels [MRLs] we

analyses of samples from Phase I than from Phase II; data values shown below the MRLs are from Phase I. When 

10 data points were available, no box is shown.)

n/N number of detection

ZINC

LEAD

0.1

1.0

10.0

100.0

0.1

1.0

10.0

100.0

0.1

1.0

10.0

100.0

URBAN

AGRICULTURAL

MIXED-USE

FORESTED

NICKEL

ARSENIC CHROMIUM

URBAN

AGRICULTURAL

MIXED-USE

FORESTED

EXPLANATION

15/18 3/8 4/7 0/1

10/15 4/6 0/3 0/0 15/18 3/9 3/10 0/1

15/19 5/9 3/10 0/1

18/19 3/9 2/10 0/1

Data value

90th percentile

75th percentile

Median

25th percentile

10th percentile

/number of samples

Phase II minimum

CONCENTRATION, IN MICROGRAMS PER LITER

COPPER

18/18 4/7 3/4 0/0

reporting level
23

The manhole sites receive only storm runoff and are

separated from any combined sewer overflow systems

upstream of the sampling locations; the discharge

from each enters the Willamette River directly downstream of each sampling location. The highest

observed concentrations of copper and zinc (45 and

290 μg/L, respectively) occurred at the site at Harbor

Way, and the highest concentrations of lead and nickel

(67 and 12 μg/L, respectively) occurred at the I-84

runoff site. The highest observed concentrations of

arsenic and chromium (4 and 16 μg/L, respectively)

occurred at A-3 Channel in Eugene.

Relation with Suspended Sediment and

Streamflow

Positive, significant (p<0.005) correlations were

found between unfiltered-water suspended-sediment

concentrations and detected unfiltered-water concentrations of chromium, copper, lead and zinc at urban

sites from Phases I and II (table 10).

Correlations with suspended sediment for detections of arsenic, cadmium, and nickel were not significant. Cadmium may not have correlated well due to

the relatively small number of detections. Because

suspended-sediment concentration is highly correlated

with flow and relatively independent of drainage area

size, these results support the finding from Phase I that

higher concentrations of trace elements occur during

higher flow.

For these correlations, concentrations in unfiltered

water, rather than in filtered water, were used because

more unfiltered-water samples were collected and t

contained detectable concentrations of trace eleme

more often than filtered water samples. Data were

insufficient to compute correlations for agricultura

mixed use sites.

Among the urban sites sampled, two different s

types are represented: (1) streams receiving mixed

runoff from residential, light commercial, and light

industrial land uses, hereafter referred to as residen

streams, and (2) manholes, sewers, and ditches rec

ing runoff specifically from industrial and commerc

areas, or roads, hereafter referred to as industrial

streams. Of the sites listed as “urban” in tables 6, 7

and 8, the industrial sites include A-3 Channel in

Eugene, Beaverton Creek near Orenco, the urban o

fall at Greenway Bicycle Bridge in Eugene, comm

cial runoff at Harbor Way in Portland, and the I-84

runoff site. All other urban sites are considered res

dential streams.

The influence of residential and industrial site

types on trace-element concentrations is shown in 

ure 7 for chromium, copper, lead, and zinc. Trace-e

ment concentrations were the highest at industrial

sites, and the apparent relations between trace-elem

concentrations and suspended sediment have a stee

slopes for industrial sites than for residential sites. 

low suspended-sediment concentration, the relation

for residential sites and industrial sites are similar;

however, as the suspended-sediment concentration

increases, the relations diverge with the residential

trace-element concentrations becoming substantial

lower than those from the industrial sites. At high s

pended-sediment concentrations, the data from the t

different types of urban sites appear to represent di

ferent populations.

For residential sites, more data are needed to be

define the relation at moderate to high suspended-s

ment concentration. Only three residential samples

shown had high suspended-sediment concentration

two from Pringle Creek at Bush Park in Salem, and

one from Fanno Creek near Durham. No samples w

suspended-sediment concentrations between 25 an

150 mg/L from residential sites were available to b

ter define the intermediate part of the relation.

One possible explanation for the separation of 

residential samples from the industrial samples at h

sediment concentrations could be the source of the

sediments. The residential streams may have exper

enced a large degree of bank erosion as flows

increased, thus increasing the suspended-sediment

Table 10. Correlations of detected trace-element

concentrations in unfiltered water with suspendedsediment concentrations for samples from urban sites

during Phases I and II of the Willamette River Basin

Water Quality Study, Oregon, 1992–94

[Correlations were determined using Kendall’s tau (τ), a nonparametric correlation coefficient that does not require normality

(Helsel and Hirsch, 1992)]

Trace

element

Number of

samples

with

detections

Total

number

of

samples

Kendall’s

tau (τ)

Significance

(p level)

Arsenic 11 16 -0.2497 0.3184

Cadmium 7 19 .3705 .2664

Chromium 15 18 .7601 .0001

Copper 18 18 .4867 .0055

Lead 18 19 .6928 .0001

Nickel 15 18 .1933 .3472

Zinc 15 19 .5746 .0015
24

0

5

10

15

20

CHROMIUM

LEAD

0 100 200 300

0

20

40

60

80

Residential streams

Industrial streams

0.0 100 200 30

0

100

200

300

ZINC

EXPLANATION

TRACE-ELEMENT CONCENTRATION, IN MICROGRAMS PER LITER

SUSPENDED-SEDIMENT CONCENTRATION, IN MILLIGRAMS PER LITER

10

20

30

40

50

COPPER

0

Figure 7. Relations of trace-element concentrations in unfiltered water with suspended-sediment conce

at urban sites in the Willamette River Basin, Oregon, 1992–94. (Note that vertical scales are different for e

Samples for which a given trace element was not detected were excluded.)
25

concentration without increasing trace-element

concentrations.

An extreme example of this phenomenon probably

occurred at Fanno Creek at Durham on October 27,

1994. Data from that sampling were not included in

figure 7 because they represented severe outliers. On

this date, two prior days of storms had produced more

than 3 inches of rain (fig. 4), resulting in runoff that

was exceeded by less than 0.5 percent of the daily

mean streamflows recorded at that site since the beginning of the flow record in 1992 (fig. 5). Water overflowed the streambanks upstream of the sampling site,

and was observed to be flowing through fields and

wooded areas as well as the stream channel. The sample was collected at peak flow at an instantaneous discharge of 946 ft3/s (cubic feet per second), and had the

highest suspended-sediment concentration (770 mg/L)

measured during the entire Willamette Study. However, despite the high sediment concentration, unfiltered-water concentrations of copper (4 μg/L), lead

(5 μg/L), nickel (3 μg/L), and zinc (30 μg/L), were no

greater than their overall median concentrations for

the entire study (Appendix 1). Apparently the suspended sediment was primarily derived from the

erosion of streambanks and adjacent fields and did

not contribute significantly to trace-element

concentrations.

In contrast to residential streams, industrial

streams are largely confined within pipes or other noneroding structures. Their discharge should be almost

entirely composed of more highly contaminated surface runoff from roads, parking lots, other man-made

structures, and bed sediment. Industrial streams, therefore, would be expected to have relatively higher

concentrations of trace elements when suspendedsediment concentrations are high, as appears to be the

case. Indeed, concentrations of trace elements in suspended sediment from industrial sites were likely to be

higher than from residential sites during Phase I sampling. This hypothesis is supported by two samplings

that appear to be outliers on figure 7. Both samples

were from industrial streams and had particularly high

trace-element concentrations considering the observed

suspended-sediment concentrations. A sample from a

manhole in downtown Portland, collected at peak flow

during a thunderstorm in spring 1994, had elevated

concentrations of copper, lead, and zinc. The manhole,

located at Harbor Way, contains water drained primarily from commercial areas. The suspended-sediment

concentration was 42 mg/L. Unfiltered-water concentrations of copper (45 μg/L), cadmium (7 μg/L—n

shown in figure 7), and zinc (290 μg/L) at this site

were the highest observed during either phase of th

study. The sample from A-3 Channel in Eugene dur

fall, 1992, had a disproportionately high concentrat

of chromium (16 μg/L) for a suspended-sediment c

centration of 90 mg/L.

Concentrations of chromium, copper, and lead 

unfiltered and filtered water, and those associated w

suspended sediment are shown for all sites in figure 

Data shown in figure 8 do not include cases where 

element was detected in filtered water, but was

detected at lower concentrations or not at all in unfi

tered water: such cases are a result of analytical va

ability at low concentrations and represent a physic

impossibility. For chromium, copper, and lead thes

included 4, 3, and 5 samples, respectively. Note als

that the unfiltered and filtered water concentrations

shown in figure 8, in micrograms per liter, are equi

lent to parts per billion, whereas the suspended

concentrations shown, in micrograms per gram, are

equivalent to parts per million.

Because trace elements partition between the s

ment and aqueous phases, concentrations in filtered

and unfiltered water will rarely be equal. In fact, co

centrations in filtered water were often substantiall

lower than those in unfiltered water. Lead concentr

tions detected in filtered water were nearly an order 

magnitude less than those in unfiltered water, wher

copper concentrations in the filtered water were alm

one-half of the unfiltered-water concentrations. Ho

ever, considering all units in parts per billion, the s

pended phase concentrations of trace elements wer

to 7 orders of magnitude greater than dissolved pha

concentrations when corrected for the concentration 

suspended sediment. Thus, the suspended sedimen

was clearly the medium with which the greatest pe

centage of trace elements were associated during th

study.

For the most part, concentrations of chromium

copper, and lead associated with the suspended pha

were poorly correlated with concentrations in filter

water (p<0.1, 0.3, and 0.3, respectively). However,

there are many factors in addition to suspended-sed

ment concentration that affect trace-element partiti

ing, including the potential lack of equilibrium, pH

and such sediment characteristics as the amount of

iron and iron oxides, organic matter, size fraction,

amount of clay minerals and colloids, and the amo

of manganese and manganese oxides associated wi
26

Figure 8. Unfiltered water and suspended concentrations of chromium, copper, and lead compared w

filtered water concentrations in samples collected during Phases I and II in the Willamette River Basin

Water Quality Study, Oregon, 1992–94. (Suspended concentrations of trace elements were determine

for Phase II samples as [unfiltered water concentration - filtered water concentration / suspendedsediment concentration]. Samples from Phase I were measured in suspended sediment directly.)

0 6 2 4 0

20

5

10

15

0 25 5 10 15 20

0

50

10

20

30

40

0 5 1 2 3 4

0

50

10

20

30

40

0 2 4

0 5 10 15 20

0

600

100

200

300

400

500

0 1234

0

1,200

200

400

600

800

1,000

CHROMIUM

COPPER

LEAD

FILTERED WATER CONCENTRATION, IN MICROGRAMS PER LITER (PARTS PER BILLION) SUSPENDED TRACE ELEMENT CONCENTRATION, IN MICROGRAMS PER GRAM (PARTS PER MILLION)

UNFILTERED WATER TRACE ELEMENT CONCENTRATION, IN MICROGRAMS PER LITER (PARTS PER BILLION)

250

0

50

100

150

200

COPPER

LEAD

CHROMIUM
27

the sediment (Horowitz, 1991). In fact, depending on

the trace element of interest, partitioning of trace elements may be modeled by using either a linear partitioning coefficient or an isotherm (Langmuir or

Freundlich) describing adsorption’s dependence on the

availability of potential binding sites and the relative

concentrations of the trace element in solution

(Drever, 1988). That the data in figure 8 do not clearly

form such isotherms should not be surprising given the

lack of control of environmental factors, and the probable disequilibrium during storm conditions, in the

samples collected.

Current water-quality criteria for trace elements

are defined in terms of unfiltered-water samples. Some

proposals have suggested changing the criteria to

reflect filtered water analyses, presumably due to bioavailability concerns. The data from Phase I and Phase

II indicate that unless analytical methods with lower

reporting limits are used, analysis of filtered samples

will result in fewer detections and hence may more

frequently be inconclusive with respect to criterion

exceedances. Analytical methods with lower detection

limits exist, but the costs of both analysis and sampling would increase substantially. Because some trace

elements may bioaccumulate through the food chain,

concentrations of trace elements in the sediments, to

which most invertebrates and many fish are exposed,

may actually be as relevant as those in filtered water

with respect to biological concerns. Depending on the

study objectives, there may be greater value in expanding trace-element data-collection efforts to include

either bed sediments or suspended sediments, or both,

rather than focussing on the dissolved phase. These

media, as well as the tissues of fish or other aquatic

animals, are likely to provide more detailed information regarding the potential for trace-element problems

than would filtered water samples.

Organic compounds

Pesticides and OCs (organochlorine compounds)

were sampled at each site during Phase I and Phase II;

however, because data collected by the NAWQA and

Lower Columbia River Bi-State programs were

included, the total number of OC samples (73) is less

than that for pesticides in filtered water (92). As with

the trace-element data, the analytical results presented

below represent episodic conditions for specific sites

but may not accurately reflect basinwide concentrations or distributions of the constituents.

Volatile Organic Compounds

Summary statistics for detections of VOCs

(volatile organic compounds) in unfiltered wate

OCs in unfiltered water, and pesticides in filtere

water are provided in Appendixes 3 through 6.

During Phase II, VOCs were sampled exclusive

at urban sites because it was felt that nonurban

sites would not be important. Together with the

samples from Phase I, a total of 18 VOC sampl

were collected from 12 locations in the Willame

River Basin and analyzed for 63 VOCs (table 1

Fourteen VOCs were detected at a total of four

urban sites in areas with predominantly comme

cial or industrial urban land uses. Frequency of

VOC detections ranged from five detections for

cis-1,2-dichloroethene and tetrachloroethylene 

one for naphthalene, pseudocumene, and 1,3,5-

trimethylbenzene (table 11). VOCs with analyte

concentrations of about 1 μg/L or greater occur

for benzene (1.0 and 1.5 μg/L), tetrachloroethy

ene (1.1 μg/L and 1.8 μg/L), and trichloroethyle

(1.3 μg/L).

Exceedances of Water-Quality Criteria—

Several concentrations for benzene (I-84 Runoff si

two samples), chloroform (A-3 Channel, two samp

and the urban outfall at Eugene, one sample), 1,1-

dichloroethylene (A-3 Channel, two samples, and t

urban outfall at Eugene, one sample), and tetrachlo

ethylene (A-3 Channel, two samples) exceeded the

respective HHP values (table 12). No HHP values

have been established for 1,1-dichloroethane, cis-1

dichloroethylene, methylene chloride, naphthalene

pseudocumene, 1,3,5-trimethylbenzene, or xylene.

Organochlorine Compounds

Seventy-three water samples were collected fro

39 locations in the Willamette River Basin during

Phase I and Phase II and analyzed for 17 organoch

rine compounds. Lindane, dieldrin, DDX compoun

(DDT and/or its metabolites, DDE and DDD), PCB

endosulfan, and heptachlor were detected at a total 

14 sites. The most frequently detected OCs were li

dane, dieldrin, and DDX compounds, which were

detected in roughly 30 percent of the samples in pr

dominantly agricultural and urban areas (table 13 a

fig. 9). PCBs were the next most frequently detecte

organochlorine compounds, found in about 8 perce

of the samples at two sites located in urbanized are
28

Exceedances of Water-Quality Criteria

All 19 samples with detected concentrations

of DDX compounds equaled or exceeded the Oregon

CTC and HHP criteria for ΣDDX (0.001 and

0.000024 μg/L, respectively) (table 12). Eleven of the

detected dieldrin concentrations, which were from

samples from both agricultural and urban areas,

exceeded the CTC (0.0019 μg/L), whereas all 23 of

the detected dieldrin concentrations exceeded the HHP

(0.000071 μg/L). Only three of the detected lindane

concentrations (Zollner Creek near Mt. Angel and

Champoeg Creek below Mission Creek—both agricultural) and one heptachlor concentration (the I-84 runoff site—urban) exceeded the HHPs for these

compounds (0.019 μg/L and 0.00028 μg/L, respectively). All six detected PCB concentrations from

Pringle Creek and the I-84 runoff site exceeded both

the CTC (0.014 μg/L) and the HHP for PCBs

(0.000079 μg/L).

Relation to Land Use

Although the sale and transport of DDT was

banned in 1973, DDX compounds were detected

(relatively often) in unfiltered water, and more frequently in urban than agricultural samples (38 and 26

percent, respectively—fig. 9). However, the number of

distinct sites (10) at which DDX compounds were

detected was relatively small; three sites eac

senting agricultural and mixed land uses and 

resenting urban areas. DDX compounds wer

in multiple samples from several sites, inclu

84 Runoff site and Johnson Creek at Palmbl

DDX compounds were detected in four of si

from the I-84 runoff site and in each of six s

from Johnson Creek at Palmblad Road. The 

unfiltered-water concentrations of ΣDDX o

these two sites (0.06 and 0.021 μg/L, respec

Previous studies have documented the occur

DDT and other organochlorines in Johnson 

greater detail (Edwards, 1992, 1994).

The frequency of detections of dieldrin 

lar for urban and agricultural areas (38 and 4

of samples, respectively), although the high

centrations were observed at an agricultural 

(Johnson Creek, 0.02 μg/L). Lindane was ob

more frequently in samples representing urb

than agricultural areas (44 and 33 percent, r

tively), but the highest concentrations were 

Champoeg Creek, an agricultural site. The tw

which PCBs were detected were the I-84 run

and Pringle Creek in Salem, both urban site

result of this study, the Oregon Department 

portation has initiated an investigation into p

sources of organic compounds at the I-84 ru

(Jeff Moore, Oregon Department of Transpo

Table 11. Summary statistics for detected unfiltered-water concentrations of volatile organic

compounds in the Willamette River Basin during Phases I and II of the Willamette River Basin

Water Quality Study, Oregon, 1992–94

Analyte Percent

detects

Number of

detects

Number of

samples

Median detected

concentration

(μg/L)

Maximum

concentration

(μg/L)

cis-1,2-Dichloroethylene 28 5 18 .6 .9

Tetrachloroethylene 28 5 18 .4 1.8

Trichloroethylene 22 4 18 .8 1.3

Chloroform 17 3 18 .2 .8

1,1-Dichloroethylene 17 3 18 .3 .3

1,1,1-Trichloroethane 17 3 18 .8 .9

Benzene 17 3 18 1.0 1.5

Methylene chloride 17 3 18 .3 .8

1,1-Dichloroethane 11 2 18 — .4

Toluene 11 2 18 — .7

Xylene 11 2 18 — .6

1,3,5-Trimethylbenzene 6 1 18 — .3

Naphthalene 6 1 18 — .5

Pseudocumene 6 1 18 — .2
29

Table 12. Exceedances of State of Oregon criteria for organic chemicals in water for streams sampled during Phases I 

of the Willamette River Basin Water Quality Study, Oregon, 1992–94

[Water-quality criteria are from Oregon Administrative Rules, Chapter 340, Division 41, 1994; Constituents for which no criteria exist were not

included; methoxychlor and 2,4-D were omitted because criteria were not exceeded; 2,4-dinitro-o-cresol had one possible detection at Mill Creek at

Delaney Rd. near Turner which equalled the freshwater aquatic life criterion for chronic toxicity but is considered uncertain due to matrix interferen

method detection limits (MDLs) for mirex and toxaphene exceed all three criteria; these compounds were not detected, so that results are inconclusi

all sites; 1, freshwater aquatic life criteria for acute toxicity; 2, freshwater aquatic life criteria for chronic toxicity; 3, criteria for protection of human

health for water and fish ingestion (carcinogenic risk level of 1 in 1 million); †, not detected, but results inconclusive because MDLs were larger tha

criteria for chronic toxicity; ‡, not detected, but results inconclusive because MDLs were larger than the human health criteria; shaded areas, not

sampled; blank areas, sampled with no exceedance detected]

Site

Criteria exceeded

Volatile organic

compounds Organochlorine compounds Pesticides

Benzene

Chloroform

1,1-Dichloroethylene

Tetrachloroethylene

DDT+DDE+DDD

Dieldrin

Heptachlor

Lindane

PCBs

Chlorpyrifos

Malathion

Parathion

Urban sites

Urban outfall at Greenway Bicycle Bridge at Eugene 3 3 ‡ ‡ ‡ †,‡

A-3 Channel at Wallis & 5th St. Eugene 3 3 3 2,3 ‡ ‡ †,‡ 1,2

Pringle Creek at Bush Park at Salem 2,3 2,3 ‡ 2,3

Beaverton Creek at 216th Ave. near Orenco ‡ ‡ ‡ †,‡

Bronson Creek at 185th Ave. near Aloha ‡ ‡ ‡ †,‡

Fanno Creek at Durham ‡ 2,3 ‡ †,‡

Johnson Creek at Milwaukie 3 2,3 ‡ †,‡

Urban Runoff at Harbor Way at Portland ‡ ‡ ‡ †,‡

Interstate-84 Runoff at Portland 3 2,3 2,3 3 2,3 2

Agricultural sites

Long Tom River at Bundy Bridge near Monroe ‡ ‡ ‡ †,‡

Lake Creek at Pine Grove Drive ‡ ‡ ‡ †,‡

Muddy Creek near Peoria ‡ †,3 ‡ †,‡

Calapooia River at Albany ‡ ‡ ‡ †,‡

Thomas Creek at Kelly Rd. near Jefferson ‡ ‡ ‡ †,‡

Rickreal Creek at mouth near Salem ‡ ‡ ‡ †,‡

Mill Creek at Delaney Rd. near Turner ‡ †,3 ‡ †,‡

S. Yamhill River at McMinnville ‡ ‡ ‡ †,‡

N. Yamhill River near McMinnville ‡ ‡ ‡ †,‡

Palmer Creek at Dayton ‡ ‡ ‡ †,‡

Champoeg Creek below Mission Cr. near Butteville 2,3 2,3 ‡ 3 †,‡

Zollner Creek near Mount Angel 2,3 2,3 ‡ 3 †,‡ 2 1,2

Pudding River at Aurora 2,3 †,3 ‡ †,‡

Dairy Creek at Rte. 8 near Hillsboro ‡ 3 ‡ †,‡

Johnson Creek at Palmblad Rd. near Gresham 2,3 2,3 ‡ †,‡ 2

Mixed-use sites

Coast Fork Willamette River at Seavey Loop Rd ‡ ‡ ‡ †,‡

Marys River at Corvallis 2,3 ‡ ‡ †,‡

Willamette River below Corvallis WTP ‡ ‡ ‡ 2,3 †,‡

Luckiamute River near Buena Vista ‡ ‡ ‡ †,‡

Santiam River at Jefferson ‡ ‡ ‡ †,‡

Willamette River upstream Hwy. 219 at Newberg ‡ ‡ ‡ †,‡

Molalla River near Canby ‡ ‡ ‡ †,‡

Tualatin River at West Linn 2,3 3 ‡ †,‡

Willamette River at Portland 2,3 ‡ ‡ †,‡

Willamette River above St. Johns Bridge at Portland ‡ ‡ ‡ †,‡

Willamette River at Linnton ‡ ‡ ‡ †,‡

Forested sites

Coast Fork Willamette River below Big River near London ‡ ‡ ‡ †,‡

Mack Creek near Blue River ‡ ‡ ‡ †,‡

McKenzie River at mouth near Eugene ‡ ‡ ‡ †,‡

Rock Creek near Philomath ‡ ‡ ‡ †,‡
30

Table 13. Summary statistics for detected unfiltered-water concentrations of organochlorine

compounds in the Willamette River Basin during Phases I and II of the Willamette River

Basin Water Quality Study, Oregon, 1992–94

[DDT+DDE+DDD is considered a single compound for purposes of detections; nondetection of individual analytes

of DDT, DDE, and DDD are assigned a value of 0 μg/L (micrograms per liter) for the purpose of summing

concentrations; —, not calculated]

Analyte Percent

detects

Number of

detects

Number of

samples

Median detected

concentration

(μg/L)

Maximum

concentration

(μg/L)

Lindane 32 23 73 0.002 0.032

Dieldrin 32 23 73 .002 .02

DDT + DDE + DDD 26 19 73 .003 .06

DDE 21 15 73 .002 .03

DDT 19 14 73 .002 .03

DDD 11 8 73 .001 .002

PCB 8 6 73 .1 .2

Endosulfan 4 3 73 .002 .006

Heptachlor 1 1 73 — .001

Figure 9. Concentrations of selected organochlorine compounds detected in unfiltered water in relation to vario

land uses during Phases I and II of the Willamette River Basin Water Quality Study, Oregon, 1992–94.

0.001

0.010

0.100

1.000

DDT + DDE + DDD DIELDRIN

0.001

0.010

0.100

1.000

LINDANE

AGRICULTURAL

MIXED-USE

FORESTED

6 10 3 0 0

7 13 3 0

6 16 1

PCBs

AGRICULTURAL

MIXED-USE

FORESTED

URBAN

URBAN

0.0001

0.0001

CONCENTRATION, IN MICROGRAMS PER LITER

6000

EXPLANATION

90th percentile

75th percentile

Median

25th percentile

10th percentile

Data value

Number of det

Minimum repo

n

Number of sam

URBAN

AGRICULTUR

MIXED-USE

FORESTED

TOTAL

level
31

oral commun., 1995), and the City of Salem has begun

a similar investigation in the Pringle Creek watershed

(Genevieve Brooks Bishop, City of Salem Department

of Public Works, oral commun., 1996).

Sediment-Water Partitioning

Among the samples collected during the fall 1994

high-flow period, eight water samples were collected

from six sites and analyzed for OCs in the dissolved

and suspended phases. Of the 17 compounds included,

only DDX compounds were consistently detected in

both the dissolved and suspended phases; these were

found in two samples from Johnson Creek and one

sample each at the I-84 runoff and Pudding River sites.

Analytical results from these four samples were used

to determine the partitioning between the dissolved

and suspended phases and were compared to theoretical equilibrium distributions for the same samples. For

the sample from the Pudding River, none of the DDX

compounds were detected in the dissolved phase; for

that sample, a range of possible partitioning relations

were calculated using values of 0 micrograms per liter

and the MRL value (0.001 μg/L).

Seventy to 89 percent of the combined mass of

DDX compounds was observed to be associated with

the suspended phase (fig. 10) for the four samples

examined. It was expected that these compounds

would preferentially associate with the suspended

phase because they are known to be hydrophobic, with

organic carbon-water partitioning coefficient (Koc)

values of 770,000 for DDD, 4,400,000 for DDE and

243,000 for DDT (U.S. Environmental Protection

Agency, 1990). Theoretical computations (Appendix

7) predicted that 55 to 81 percent of the mass of the

DDX compounds should have been associated with

the suspended phase if the systems were at equilibrium, depending on the relative concentrations of suspended organic carbon in the samples. In all cases, the

observed amounts transported in the suspended phase

were only slightly greater than predicted, suggesting

that the systems were near equilibrium. The actual difference between observed and predicted values for

three of the samples was relatively small (8.8 to 21.4

percent), especially considering that most of the dissolved concentrations were at or near the analytical

reporting limits. Also, there is considerable uncertainty associated with the published Koc values, which

were determined in laboratories under conditions that

may not always mirror environmental conditions. The

one sample where the difference was potentially large

(between 17 and 44 percent) was the Pudding Rive

sample, and resulted from the use of a range of val

for the dissolved phase concentrations of DDX com

pounds. Concentrations of DDX compounds in the

suspended phase were also relatively low, amplifyi

the impact of using a range of possible concentrati

in the equilibrium calculations.

For the four samples discussed above, nearly 5

percent of the ΣDDX was present as DDT. This w

despite the fact that the sale and transport of DDT 

the United States was banned by the USEPA in 197

About 35 percent of the total was present as DDE, 

the remaining roughly 15 percent present as DDD.

Results for unfiltered-water analysis in all samples

from Phase II were somewhat similar, with median

50, 50, and 0 percent of the total mass present as DD

DDE, and DDD, respectively. These percentages a

also similar to values determined in a 1987–90 stud

in the Yakima River Basin, Washington (J.F. Rinell

and others, 1992) and a 1990–91 study in the Owy

and Malheur River Basins in eastern Oregon

(F.A. Rinella, and others, 1994). The percentages o

DDT, DDE, and DDD in unfiltered-water samples

from these other studies were 30-40, 50, and 10-20

percent of mass, respectively.

The fraction of organic compounds found in th

suspended phase is controlled by the Koc values, th

concentration of suspended organic carbon (SOC), 

the degree to which equilibrium is achieved. Becau

the fraction associated with the suspended phase at

equilibrium is directly related to the concentration 

SOC, the greatest mass of these compounds will be

in the suspended phase when SOC is high (fig. 10;

Appendix 7). At the lowest SOC concentration of t

four samples (1.6 mg/L at Pudding River), equilibri

calculations predict that over 50 percent of the mas

DDX compounds, which have relatively high Koc

values, should be in the suspended phase, and at th

highest SOC concentration (7.4 mg/L at the I-84 R

off site) the equilibrium fraction in suspended sedi

ments increased to 80 percent. In contrast, dieldrin 

lindane, with much lower Koc values, were found

almost completely in the dissolved phase, with SO

concentrations ranging from 0.5 to 5.7 mg/L.

The partitioning of dieldrin and lindane in unfi

tered- and filtered-water samples from Phases I and 

was also examined using the method described in

Appendix 7, modified to determine the equilibrium

mass in the dissolved phase. Both dieldrin and lind

have substantially lower Koc values than the DDX

compounds (1,700 and 1,080 mL/g, respectively [U
32

Environmental Protection Agency, 1990]). As a result,

the proportions of each compound expected to be in

the dissolved phase at equilibrium are much higher,

averaging approximately 96 percent for dieldrin and

greater than 99 percent for lindane at the SOC concentrations observed. Indeed, for the five samples in

which dieldrin was detected in both unfiltered and filtered water, the observed proportion in filtered water

ranged from 60 to 160 percent (median 105 percent).

Likewise, the 4 samples in which lindane was detected

in both unfiltered and filtered water had a range of 83

to 119 percent (median 101 percent) of the compound

in the dissolved phase. All other detections of dieldrin

or lindane in unfiltered water were at concentrations

below the respective MDLs for those compounds in

filtered water. Obviously, it is impossible for greater

than 100 percent of a compound to be in any phase;

these results illustrate the potential problems encountered when comparing data from different analytical

procedures at relatively low concentrations. N

less, it is apparent from the analytical that th

of dieldrin and lindane were mostly present i

solved phases for these samples, a result that 

agreement with the equilibrium calculations.

Dissolved Pesticides

Ninety-two water samples were collected 

locations in the Willamette River Basin and 

for 94 pesticides and metabolite products (Ap

5 and 6). Included among these were 58 wate

from 32 locations that were analyzed for a se

azine and related herbicides.

Exceedances of Water-Quality Crite

Of the pesticides analyzed, CTC, ATC, o

values for the State of Oregon have been esta

Figure 10. Observed and equilibrium fraction of DDT and metabolites present in suspended phase for four sam

during Phase II of the Willamette River Basin Water Quality Study, Oregon, 1994. (Data from the Pudding Rive

considered to be estimates because neither DDT nor its metabolites were detected in the dissolved phase. Fo

purposes of this analysis, concentrations of DDT and its metabolites in the Pudding River sample were calcula

assuming a range of concentrations in the dissolved phase from zero micrograms per liter [μg/L] to the value o

method detection limit [0.001 μg/L]. SOC, suspended organic carbon; mg/L, milligrams per liter. Refer to Appen

for explanation of calculation.)

0

100

20

40

60

80

PERCENT OF MASS OF DDT AND METABOLITES IN THE SUSPENDED PHASE

OBSERVED

EQUILIBRIUM

PUDDING RIVER JOHNSON CREEK

OCTOBER 27, 1994

(SOC = 5.7 mg/L)

JOHNSON CREEK

OCTOBER 28, 1994

(SOC = 1.8 mg/L)

INTERSTATE-84 RUNOFF

OCTOBER 28, 1994 NOVEMBER 8, 1994

CALCULATED

RANGE DUE TO

NONDETECTS

(SOC = 1.6 mg/L) (SOC = 7.4 mg/L)
33

for only six compounds (table 12). Chronic toxicity

criteria were exceeded at one site each for chlorpyrifos

and parathion, and at two sites for malathion. One

sample at Mill Creek may have had a detection of 2,4-

dinitro-o-cresol, although laboratory results for this

sample were uncertain due to matrix interferences. Of

the six compounds with established criteria, only chlorpyrifos was detected in more than 10 samples. No

exceedances were found for methoxychlor or 2,4-D.

It is important to note that other compounds were

detected at levels that may be harmful to aquatic life,

but for which State of Oregon criteria have not been

established. For example, more than 50 percent of the

43 detections of diazinon exceeded the recommended

threshold value of 0.009 μg/L established by the

National Academy of Sciences and National Academy

of Engineering (1973). The highest of these concentrations was 1.2 μg/L at Zollner Creek. Other threshold

values established by the National Academy of Sciences and National Academy of Engineering that were

exceeded were for azinphos methyl (0.001 μg/L), carbaryl (0.02 μg/L), and diuron (1.6 μg/L).

Relation to Pesticide Applications and Land Use

Pesticide applications—The 25 pesticide and

metabolite products detected most frequently in

the basin are listed in table 14, in descending order

of occurrence. Between 80 and 90 percent of the

water samples collected had detectable concentrations of atrazine, simazine, and metolachlor, ranging in concentration from 0.002 to 3.5 μg/L. These

percentages were consistent with the 85 to 95 percent detections observed for samples collected in

the Willamette River at Portland during 1994 as

part of the Columbia River Bi-State Study (Fuhrer

and others, 1996). Desethylatrazine, diuron,

hexazinone, diazinon, cycloate, desisopropylatrazine, and terbacil were detected in 61 to 37 percent

of the samples, in concentrations ranging from

0.001 to 9.0 μg/L. In addition, roughly one out of

every three samples contained detectable concentrations of DCPA (dacthal), EPTC, napropamide,

and prometon.

Of the 94 pesticides in filtered water that were

analyzed (Appendixes 5 and6, 33 were not listed as

used in the Willamette River Basin in the 1987 estimates of Reinhold and Witt (1989); these compounds

were analyzed because they are included in the analytical schedules for pesticides available from the

NWQL. Nonetheless, 5 of these unlisted compounds

were detected during 1992–94; most notably, ethop

and tebuthiuron were detected in 24 and 21 sample

respectively (table 14, Appendix 5). Of the remaini

61 pesticides analyzed that are used in the basin, 4

were detected at least once. Other compounds know

to have been used in the basin but which were not a

lyzed (owing to a lack of available methods) includ

benomyl, captan, diclofop, ethofumesate, glyphosa

maneb, and metaldehyde (table 5).

If 1987 pesticide-use estimates accurately refle

current (1992–94) use and if these compounds beh

similarly in the environment, then 1987 usage shou

be a useful predictor of detections in the water sam

ples. However, data in table 14 generally indicate li

relation between pesticide-use estimates and detect

frequency. Although some widely used pesticides su

as atrazine, diuron, and simazine were frequently

detected, others, such as 2,4-D, were not. Converse

several frequently detected compounds, including

prometon, ethoprop, and tebuthiuron were not listed 

used in the basin. Possible reasons for the limited s

cess of this comparison include (1) pesticide use ha

probably changed considerably since 1987, (2) pes

cides may be removed from the aqueous phase by

sorption to sediments, partitioning into other organ

material, volatilization, or biological or chemical

transformation, (3) spatial and temporal variability 

crop planting and rotation practices may have resul

in uncertainty in pesticide-use estimates; (4) the tim

ing of pesticide application may not have coincided

with water sample collection; (5) below average ra

fall and runoff during spring 1994 may have limite

pesticide transport to streams (fig. 4), and (6) analy

cal performance may have limited the frequency of

detection of some compounds.

Land use—Detections of some pesticides did

appear to be associated with particular land uses. T

investigate this relation, 16 of the 25 pesticides we

grouped as follows: (1) compounds primarily detec

in urban areas (fig. 11), (2) compounds primarily

detected in agricultural areas (fig. 12), and (3) com

pounds detected in both urban and agricultural area

(fig. 13). Note that the numbers of samples collecte

urban, agricultural, mixed-use, and forested site typ

(24, 47, 19, and 3, respectively) were not equal.

Between 50 and 71 percent of the 24 samples (

14, and 12) collected at urban sites contained detec

able concentrations of diazinon, prometon, or tebut

uron (fig. 11), whereas, only 6 to 40 percent of the 

samples (19, 11, and 3) collected at agricultural sit
34

contained detectable concentrations of these pesticides. Median concentrations of diazinon, prometon,

and tebuthiuron in samples from urban sites were

roughly three times those observed in samples from

the agricultural sites. However, the highest concentrations of diazinon were found at agricultural sites.

In contrast, carbofuran, EPTC, ethoprop, fonofos,

napropamide, and terbacil were found more frequently

at agricultural sites. Between 34 and 64 percent of the

47 samples (16 to 30) collected at agricultural sites

contained detectable concentrations of these six pesticides, (fig. 12) compared to only 0 to 17 percent of the

24 samples (0 to 4) collected at urban sites. Median

concentrations for carbofuran, EPTC, ethoprop,

napropamide, and terbacil were from two to more than

six times greater in samples from agricultural sites

than in samples from urban sites; the median concentration for fonofos was slightly greater in samples

from the urban sites, but it was based on only four

detections.

Atrazine, carbaryl, chlorpyrifos, DCPA, diuron,

metolachlor, and simazine were detected relatively frequently in samples from both urban and agricultural

sites (fig. 13). Frequencies of detection rang

88, 100, and 84 percent (21, 47, and 16 sam

atrazine in the urban, agricultural, and mixed

respectively, to 17, 29, and 16 percent (4, 14

samples), respectively, for carbaryl. Althoug

rifos and DCPA were detected in 13 and 14 

(27 and 21 percent) at agricultural sites, they 

detected somewhat more frequently at urban 

13 samples, 37 to 54 percent, respectively). 

the compounds in figure 13, the highest conc

were observed at agricultural sites. With the 

of chlorpyrifos, the median concentrations w

highest at agricultural areas.

Spatial and temporal variations—Agr

activities in the northern portion of the Willa

River Basin are more diverse than those in t

ern portion. The northern portion includes m

crops, orchards, vineyards, and nurseries tha

southern portion, where grains, hay and sila

grass and legume seeds predominate (table 4

illustrate the effect of differing agricultural p

water quality in the basin, the frequencies of 

detections in the northern and the southern p

Table 14. Summary statistics of the 25 most frequently detected pesticides in the Willamette River Basin durin

and II of the Willamette River Basin Water Quality Study, Oregon, 1992–94

[Pesticide usage for 1987 from Reinhold and Witt (1989); μg/L, micrograms per liter; —, not applied; NL, not listed by Rinehold and W

Analyte Percent

detections

Number of

detections

Number of

samples

Median detected

concentration

(μg/L)

Maximum

concentration

(μg/L)

Willamette Basin

Pesticide usage, 19

Pounds applied Ra

Atrazine 90 84 93 .052 2.7 409,400 

Simazine 82 76 93 .094 3.5 166,600 

Metolachlor 81 75 93 .026 3.3 42,450 2

Desethylatrazine 61 56 93 .010 .27 — —

Diuron 54 44 81 .32 9.0 552,500 

Hexazinone 48 28 58 .003 .040 19,000 4

Diazinon 47 44 93 .015 1.2 122,400 1

Cycloate 43 25 58 .002 .020 11,872 5

Desisopropylatrazine 40 23 58 .004 .023 — —

Terbacil 37 34 90 .027 1.0 19,170 4

DCPA (Dacthal) 35 32 93 .003 .029 365 12

EPTC 32 29 93 .008 1.0 78,600 2

Napropamide 29 27 93 .033 1.6 74,790 2

Prometon 29 27 93 .013 .068 NL N

Chlorpyrifos 26 24 93 .010 .043 120,710 1

Ethoprop 26 24 93 .011 3.1 NL N

Fonofos 26 24 93 .012 .10 114,100 1

Carbaryl 23 21 93 .010 2.0 119,500 1

Carbofuran 23 21 93 .110 9.0 10,740 5

Tebuthiuron 23 21 93 .032 .12 NL N

Metribuzin 21 19 93 .038 .41 3,570 8

Pronamide 20 18 93 .012 .098 21,770 4

Trifluralin 17 16 93 .006 .018 23,410 3

Trichlopyr 13 11 82 .18 .72 20,980 4

2,4-D 12 10 82 .18 .79 330,700 
35

the basin were compared for the compounds represented in figures 11–13 (fig. 14). Agricultural sites

located in Clackamas, Marion, Multnomah, Polk,

Washington and Yamhill Counties were designated 

northern, whereas those in Benton, Lane, and Linn

Counties were designated as southern (fig. 1). The d

analysis was limited to samples collected during 19

because these samples represent the appropriate sp

tial (basinwide) and temporal (spring and fall sampling) coverages for the analysis. Detections of the

same 16 compounds at urban sites were also includ

in figure14 for comparison purposes. The division 

sites resulted in unequal group sizes, which may ha

introduced some bias. Additional bias may have be

introduced from differences in the number of samplings at individual sites in the northern and southe

portions of the basin, and in variations in hydrolog

conditions among all sites at the time of sampling.

Pesticides detected in both the northern and sou

ern agricultural areas with similar frequencies

included atrazine, carbaryl, diuron, metolachlor,

simazine, and terbacil. Pesticides detected in only t

northern agricultural areas included carbofuran, ch

rpyrifos, DCPA, diazinon, ethoprop, napropamide, 

tebuthiuron. EPTC, fonofos, and prometon were

detected in both parts of the basin, but generally th

detection frequency was greater in the northern agr

cultural area. Maximum pesticide concentrations w

greatest in samples collected at the northern agricu

tural sites with the exception of carbaryl (2.0 μg/L

Long Tom River at Monroe, 5–19–94) (Harrison an

others, 1995).

To determine temporal variability, the data wer

further divided into spring 1994 and fall 1994 samp

(fig. 15). Dividing the data in this manner can lead 

difficulties because the effects of any inherent bias

are amplified in the resulting smaller data sets. Det

tion frequencies for atrazine, carbaryl, diuron, EPT

metolachlor, and simazine during the spring sampl

in the northern agricultural areas were generally sim

lar to those observed during the spring sampling in 

southern agricultural areas. Likewise, the frequenc

of detection for these six pesticides during the fall

sampling were similar in the northern and southern

agricultural areas with the exception of carbaryl an

EPTC. In both regions, the detection frequencies fo

these pesticides increased slightly from spring to fa

with the exception of carbaryl and EPTC. Detectio

frequencies for carbofuran, chlorpyrifos, ethoprop,

napropamide, tebuthiuron, EPTC, fonofos, and

Figure 11. Concentrations of selected pesticides primarily

associated with urban land use during Phases I and II of the

Willamette River Basin Water Quality Study, Oregon, 1992–

94. (Distributions based on detections only; the numbers of

samples associated with the land-use types are given in the

explanation. Data represent filtered water samples.)

TEBUTHIURON

DIAZINON

PROMETON

AGRICULTURAL

MIXED-USE

FORESTED

CONCENTRATION, IN MICROGRAMS PER LITER

URBAN

0.001

0.010

0.100

1.000

10.000

12 3 6 0

17 19 8 0

14 11 2 0

n =

n =

n =

0.001

0.010

0.100

1.000

10.000

0.001

0.010

0.100

1.000

10.000

EXPLANATION

90th percentile

75th percentile

Median

25th percentile

10th percentile

Data value

Number of detections

Method detection limit

n

Number of samples:

URBAN

AGRICULTURAL

MIXED-USE

FORESTED

TOTAL

24

47

19

3

93
36

prometon in the northern areas were also slightly

greater during the fall than the spring. The apparent

increases in detection frequencies during fall sampling

may have been related to the different hydrologic conditions associated with these time periods; fall samples

were obtained during high flows, while spring samples

were obtained at relatively lower flows. Alternatively,

the differences between the two sample times may

have been an artifact of the repeated sampling at specific sites during fall 1994, which might have inflated

the importance of specific pesticides at the fall sites.

Despite the potential biases, distinct diff

are apparent in the patterns of pesticide runo

between the northern and southern portions 

Willamette River Basin. These patterns refle

agricultural diversity in the north, where row 

orchard fruits and nuts, and nursery plants a

tant products in addition to grass seed, whea

other grains, and where many different pesti

frequently found in the runoff. On the other 

fewer crops consume the largest percentage 

agricultural lands in the southern portions of 

CARBOFURAN

ETHOPROP

TERBACIL

EPTC

NAPROPAMIDE

FONOFOS

0.001

0.010

0.100

1.000

10.000

0.001

0.010

0.100

1.000

10.000

0.001

0.010

0.100

1.000

10.000

CONCENTRATION, IN MICROGRAMS PER LITER

n = 2 16 3 0

n = 2 16 6 0

n = 1 20 6 0 n = 0 30 4 0

n = 4 16 4 0

n = 4 19 6 0

AGRICULTURAL

MIXED-USE

FORESTED

URBAN

AGRICULTURAL

MIXED-USE

FORESTED

URBAN

EXPLANATION

90th percentile

75th percentile

Median

25th percentile

10th percentile

Data value

Number of detections

Method detection limit

n

Number of samples:

URBAN

AGRICULTURAL

MIXED-USE

FORESTED

TOTAL

24

47

19

3

93

Figure 12. Concentrations of selected pesticides primarily associated with agricultural land use during Phases I a

II of the Willamette River Basin Water Quality Study, Oregon, 1992–94. (Distributions based on detections only; th

numbers of samples associated with the respective land-use types are given in the explanation. Data represent

filtered water samples.)
37

AGRICULTURAL

MIXED-USE

FORESTED

MIXED-USE

FORESTED

SIMAZINE

METOLACHLOR

ATRAZINE

CHLORPYRIFOS DCPA

DIURON

0.001

0.010

0.100

1.000

10.000

0.001

0.010

0.100

1.000

10.000

0.001

0.010

0.100

1.000

10.000

n = 9 13 2 0

n = 19 43 14 0

31/44

n = 21 47 16 0

n = 13 14 5 0

n = 19 44 12 0

URBAN

URBAN

CARBARYL

n = 4 14 3 0

0.001

0.010

0.100

1.000

10.000

CONCENTRATION, IN MICROGRAMS PER LITER

n = 9/20 4/4 0/3

EXPLANATION

90th percentile

75th percentile

Median

25th percentile

10th percentile

Data value

Number of detections

Method detection limit

n

Number of samples:

URBAN

AGRICULTURAL

MIXED-USE

FORESTED

TOTAL

24

47

19

3

93

Figure 13. Concentrations of selected pesticides associated with both agricultural and urban land uses during

Phases I and II of the Willamette River Basin Water Quality Study, Oregon, 1992–94. (The method detection limit for

atrazine is 0.001micrograms per liter. Distributions are based on detections only; the numbers of samples associated

with the respective land-use types are given in the explanation. The numbers of samples at the various sites types

were different for diuron and are given in the plot for diuron. Data represent filtered water samples.)

AGRICULTURAL
38

0

100

20

40

60

80

0

100

20

40

60

80

AtrazineCarbaryl Carbofuran ChlorpyrifosDCPADiuronDiazinonEPTCEthopropFonofos Metolachlor Napropamide Prometon Simazine Tebuthiuron Terbacil

0

100

20

40

60

80

Atrazine

Carbaryl

Carbofuran

Chlorpyrifos

DCPA

Diazinon

Diuron

EPTC

Ethoprop

Fonofos

Metolachlor

Napropamide

Prometon

Simazine

Tebuthiuron

Terbacil

FREQUENCY OF DETECTION, IN PERCENT

n = 11 3 0 0 0 0 8 3 0 1 10 0 1 11 0 10

NORTHERN AGRICULTURAL SITES, N=30

n = 14 2 0 5 12 13 8 4 2 2 15 1 10 13 8 1

URBAN SITES, N=17

SOUTHERN AGRICULTURAL SITES, N=11

EXPLANATION

n= Number of detection

N= Number of samples

n = 30 8 14 11 12 15 21 13 14 13 28 17 9 27 3 18

Figure 14. Detection frequencies for selected pesticides at northern agricultural, southern agricultural, and urba

sites during Phase II of the Willamette River Basin Water Quality Study, Oregon, 1994.
39

0

20

40

60

80

100

URBAN SITES

NORTHERN AGRICULTURAL SITES

SOUTHERN AGRICULTURAL SITES

FREQUENCY OF DETECTION, IN PERCENT

N = 11

6 1 0 2 4 6 4 3 1 0 5 0 4 6 2 1 8 1 0 3 8 7 4 1 1 2 10 1 6 7 6 0

13 4 3 3 7 8 8 6 6 4 11 5 1 10 0 5 17 4 11 8 5 7 13 7 8 9 17 12 8 17 3 13

5 0 0 0 0 0 5 0 0 1 5 0 1 5 0 5 = n

=n =n

=n =n

EXPLANATION

n= Number of detections

N= Number of samples

N = 6

N = 13 N = 17

0

20

40

60

80

100

N = 5

Atrazine

Carbaryl

Carbofuran

Chlorpyrifos DCPA

Diazinon Diuron EPTC

Ethoprop Fonofos

Metolachlor

Napropamide Prometon Simazine

Tebuthiuron Terbacil

SPRING FALL

6 3 0 0 0 0 3 3 0 0 5 0 0 6 0 5 =n

N = 6

0

20

40

60

80

100

Atrazine

Carbaryl

Carbofuran

Chlorpyrifos DCPA

Diazinon Diuron EPTC

Ethoprop Fonofos

Metolachlor

Napropamide Prometon Simazine

Tebuthiuron Terbacil

Figure 15. Comparison of spring and fall pesticide detection frequencies at northern agricultural, southern

agricultural, and urban sites during Phase II of the Willamette River Basin Water Quality Study, Oregon, 1994.
40

(table 4), where the numbers of pesticides detected

were fewer but were at relatively high frequencies.

Figures 14 and 15reflect and corroborate the findings

from figures 11–13. Diazinon, which was detected

somewhat more frequently at urban sites than agricultural sites (figs. 11 and14), was not detected at all at

southern agricultural sites. Diazinon was also detected

more frequently during spring at urban sites but was

detected more frequently during the fall at the northern

agricultural sites (fig. 15). Terbacil was not detected at

any urban sites (figs. 12 and 14), and was detected

somewhat more frequently in the fall than in the spring

at the agricultural sites.

The number of different dissolved pesticides

detected at individual sites is shown in figure 16.

Among all sites, the 25th, 50th, 75th, and 90th percentiles of the number of detected pesticides were 3, 8,

15, and 24 compounds, respectively. The greatest

numbers of pesticides were detected at Johnson Creek

near Palmblad Road and Zollner Creek near Mt.

Angel, with 29 and 34 different compounds found,

respectively.

Some caution is required in the interpretation of

figure 16. Note that the figure does not indicate the

concentrations of the detected pesticides, or the frequency at which given pesticides were detected, nor

does it include other organic compounds such as

VOCs or OCs in unfiltered water. The numbers of pesticides detected are undoubtedly affected by the frequency of sampling at the respective sites; some sites

such as Johnson Creek, Zollner Creek, and the Willamette River at Portland were sampled as many as

five or six times during Phases I and II, and at a variety

of flow conditions, whereas other sites such as mainstem sites on the Willamette River at Corvallis or

Newberg, and small tributary sites such as Palmer

Creek near Dayton or Rickreal Creek near Salem,

were sampled just once each at low flows. However,

sites were chosen for multiple samplings based on

their likelihood of reflecting the most important or

indicative pesticide loading processes in the Willamette River Basin, and the relative differences in the

number of compounds detected may not have changed

significantly had all sites been sampled at equal frequencies.

At several sites just one pesticide was detected in

the water. Cycloate was found at forested sites on

Lookout Creek, the Coast Fork Willamette River, and

Rock Creek. Concentrations of cycloate in each sample at these sites were below the MDL of 0.01 μg/L

(Harrison and others, 1995) and the probabi

positive detections is, by definition, greater 

cent, even though cycloate was never detect

samples. Cycloate was also the only pesticid

in filtered water at the Santiam River near Je

was one of two pesticides detected at the No

River near McMinnville, also at concentratio

the MDL.

Of considerable interest in figure 16 are 

with the most compounds detected (16 or gr

senting the highest quartile). This group incl

cultural sites (Muddy Creek at Peoria, Long 

at Bundy Bridge, Mill Creek at Turner, Cha

Creek at Champoeg Park, Zollner Creek nea

Angel, Pudding River at Aurora, Dairy Creek 

near Hillsboro, and Johnson Creek near Palm

Road), 2 sites reflecting mixed uses upstream 

atin River at West Linn, and the Willamette 

Portland), and 2 urban sites (Fanno Creek ne

and the I-84 runoff site). To a large extent th

includes the sites with the highest observed 

trations of many of the individual pesticides

agricultural sites during storm runoff. For ex

Zollner Creek accounted for the highest obs

concentrations of atrazine, carbofuran, diazin

EPTC, and simazine (3.1, 9, 1.2, 9, 1, and 3

respectively), Champoeg Creek accounted f

est observed concentrations of metolachlor a

napropamide (3.3 and 1.6 μg/L, respectively

Creek was the location of the highest concen

ethoprop and terbacil (3.1 and 1 μg/L, respec

the highest concentration of carbaryl (2 μg/L

observed at the Long Tom River (Appendixe

Harrison and others, 1995). Of these high co

trations, all values except those for diazinon 

at Zollner Creek were from samples collecte

storm flow.

The mixed use sites that are included in 

quartile provide good examples of sites that 

variety of upstream land and pesticide uses, 

though the observed concentrations were on

high. For instance, 24 different pesticides we

in the Tualatin River at West Linn, which re

off from the large variety of land uses within 

ton County (including rapidly expanding urb

industrial uses and a diverse set of agricultu

see table 4). Among these pesticides were th

ing primarily urban usage (diazinon, promet

tebuthiuron; fig. 11, agricultural usage (carb

EPTC, ethoprop, and napropamide; fig. 12), 
41

Figure 16. Number of pesticides in filtered water detected at sites in the Willamette River Basin during Phases I and

II of the Willamette River Basin Water Quality Study, Oregon, 1992–94. (Some sites were sampled more frequently

than others; however, the numbers of pesticides detected were not corrected for the frequency of samplings at

individual sites. Map index numbers are from Harrison and others [1995]. Phase I sites that were only sampled for

bed sediment are not included. Refer to tables 6–8 for identification of sites by map index numbers.)
42

urban and agricultural usage (atrazine, carbaryl, chlorpyrifos, diuron, DCPA, metolachlor, and simazine;

fig. 13. Upstream sites that were sampled in the Tualatin River Basin included urban sites such as Fanno

Creek at Durham (17 pesticides including the highest

observed concentration of prometon, at 0.068 μg/L),

Bronson Creek (14 pesticides), and Beaverton Creek

(6 pesticides, Phase I only), as well as the agricultural

site on Dairy Creek (18 pesticides).

There are many potential sources for the 23 different dissolved pesticides detected at the sampling site

on the Willamette River at Portland. The site is downstream of all other sampling sites in the entire basin,

with the exception of the sites on the main stem at

Linnton and at St. Johns, which were sampled once

each. Flow in the Willamette River is tidally influenced (although no estuarine water actually enters the

Willamette River) and hence at times the direction of

flow is reversed, causing mixing of inputs from the

industrial and residential areas downstream of downtown Portland, and from combined sewer overflows

(CSOs) and other storm drains in the lower reaches of

the river. Furthermore, the Tualatin and Pudding

Rivers each had 24 different dissolved pesticides

detected at their lowest sampling sites. These basins,

which are considered to be among the basins contributing the largest loads of sediments and nutrients in

nonpoint runoff in the basin (Tetra Tech, Inc., 1995),

enter the Willamette River not far upstream and probably contribute significantly to the variety of pesticides

detected at the sampling site near downtown Portland.

The I-84 runoff site, the water from which enters

the Willamette River underneath the Burnside Bridge

in downtown Portland, is interesting for the unexpectedly large variety of organic compounds detected

despite the fact that the site represents a very specific

and limited type of land use (downtown Portland freeway traffic). In addition to trace metals and VOCs,

which might be expected because they are indicative

of automobile traffic and derivatives of gasoline,

several organochlorines (DDT, PCBs, dieldrin, heptachlor, and lindane) and 16 different dissolved pesticides (including atrazine, metolachlor, simazine,

diuron, chlorpyrifos, and others) were detected. Possible sources for these compounds include (1) use by the

Oregon Department of Transportation for landscaping

and maintenance purposes along the freeway corridor,

(2) spills from vehicles transporting the chemicals

through the Portland area, (3) dirt from other locations

such as farms that was transported to the freeway and

deposited, (4) illicit dumping or drainage co

that discharge to the freeway or directly to th

drain, and (5) wet and dry deposition from a

particles. It is unknown to what extent these 

actually contribute to the occurrence of the l

ety of compounds detected at the I-84 runof

Influences of Hydrologic Conditio

The variability of constituent concentrat

loads over the course of one or several storm

larly during the first major storms following 

dry periods) was assessed at a variety of site

fall of 1994. Samples were collected several 

ing individual or successive storms (table 8) 

three urban sites (Pringle Creek, I-84 runoff 

Fanno Creek), two mixed-use sites (Tualatin 

West Linn, Willamette River at Portland Ha

five agricultural sites (Muddy Creek, Mill C

Zollner Creek, Pudding River, and Johnson 

Because some of these sites were ungaged, 

have no continuous record of flow, strict com

of the results of the individual samplings to t

hydrographic response was not possible. Ho

partial streamflow records for some of the si

available; the relation of selected constituen

trations and loads to streamflow are shown i

figure 17A and 17B, respectively, for an agr

site (Johnson Creek) and figure 18A and 18B

tively, for a mixed use site on the main stem 

lamette River (Willamette River at Portland)

Pesticides shown in figures 17 and 18 w

selected to represent as wide a range of chem

acteristics and runoff processes as possible g

types of compounds detected at the site. For 

DDT, dieldrin, and metolachlor, shown in fi

and 17B, have relatively high (approximatel

100,000), medium (10,000), and low (200) s

partitioning coefficients, respectively. Due to 

of detected concentrations of the more hydr

compounds such as DDX compounds at the 

lamette River site, compounds are shown in 

18A and 18B that have a more narrow range 

tioning coefficients (100, 22, and 200 for atr

carbofuran, and metolachlor, respectively).

Although the water-quality sampling sit

Johnson Creek during Phase II was at Palmb

(river mile 18.0), daily mean streamflows fo

Creek in figures 17A and 17B are from the U

ing station at Sycamore Road (river mile 10

Geological Survey, in press). Travel time be
43

two sites is estimated to be roughly 4 to 8 hours at

flows indicated. Instantaneous discharges measured

at the Palmblad Road site at the time of sampling are

also shown for comparison. Constituent loads in

figure 17B are instantaneous loads; calculations are

based on streamflows measured at the Palmblad site

and on constituent concentrations for the individual

samplings. At the site on the Willamette River at Portland, only estimated daily mean flows are available

(U.S. Geological Survey, in press), and constituent

loads in figure 18B are therefore calculated using the

instantaneous concentrations and the daily mean

flows. Note that concentrations and loads in figures 17

and 18 are displayed on a logarithmic scale to allow all

constituents to be shown together.

The pattern of constituent concentrations observed

is highly dependent on streamflow conditions at the

time of sampling. Suspended sediment concentrations

typically are greater when flow is increasing than

when it is decreasing, and concentrations are greatest

just prior to peak discharge. For compounds that tend

to sorb preferentially to suspended sediment or are

influenced by sediment movement, this implies that

peak concentrations will be observed at or near the

time of peak sediment concentration, and that the

instantaneous transport (the load, in mass per unit

time) will be greatest during these times. Furthermore,

the movement of waters from interstitial areas in soils,

both within and outside of the streambed, will be

greatest after the soils and sediments have been

recently disturbed (for instance, after a long dry period

such as summer) and when additional water from rainfall can wash out the soils. Therefore the timing of

sampling relative to the timing of peak discharge can

have a marked effect on the concentrations observed.

For this reason the results in figures 17and 18must

be viewed with the knowledge that concentrations and

instantaneous loads are unknown for time periods

other than those sampled, and therefore one can only

speculate about the magnitude of loads integrated over

an entire event or time period.

Precipitation during fall 1994, was sparse until

October 25. Beginning in late October there were two

strong storms, the first during October 25–27 and the

second during October 30–November 1. The weather

was generally wet through most of November and into

December (fig. 4). The response time of flow in the

various streams in the Willamette River Basin was

dependant on such factors as rainfall intensity and

duration, land use (especially the amount of impervious surface area), the size of the contributing water

shed, and antecedent soil moisture conditions.

Discharge at the site on Johnson Creek at Palm

blad Road, which has predominantly agricultural la

use upstream, did not fully respond to the initial ra

fall until October 27 (figs. 17A and 17B). The first 

nificant peak in flow occurred on October 27, howe

the second storm, during October 30–November 1,

produced higher peak flows, even though the total 

cipitation from the first storm was the greatest of th

two (in the Portland area, where Johnson Creek is

located). This disproportionate runoff was presuma

due to dry soils prior to October 25, which became 

urated as a result of the rain during October 25–27 

afterward required decreasing amounts of rainfall t

respond. According to field observations, water-qu

ity sampling during both storms occurred at or near 

peak flows on October 27 and November 1, with ad

tional samples taken on the receding limbs of the tw

storm hydrographs on October 28 and November 3

respectively.

Sampling results at Johnson Creek indicate t

sampling of the first major runoff peaks, as envision

during planning for this project, was accomplished

Despite the somewhat lower peak flow during the

first storm, constituent concentrations were genera

the greatest during the peak runoff period for that

storm, and declined overall during the course of su

cessive storms. This observation holds for almost ev

constituent examined, including suspended sedime

and unfiltered-water concentrations of ΣDDX and

dieldrin. Although the concentrations of ΣDDX an

dieldrin near peak flow during the second storm we

decreased from those during the receding limb at th

end of the first storm, instantaneous loads of these

constituents increased slightly due to the increased

flow. Likewise, the instantaneous load of metolach

during the peak of the second storm was almost eq

to that from the peak of the first, despite a 40 perce

decrease in concentration between the two samplin

Loads for all of the constituents were equivalent or

slightly lower during the last sampling on Novemb

23, when flow was increasing, than loads on the rec

ing limb of the second storm. In general there was

a very similar pattern of concentration changes

among metolachlor, dieldrin, and ΣDDX at Johnso

Creek despite the differences in the hydrophobic ch

acteristics of the three compound types. Many of th

other dissolved pesticides detected at Johnson Cree

during the fall 1994 samplings, including atrazine a
44

15 20 25 31 5 10 15 20 

October November

1994

0

900

100200300400500600700800

DISCHARGE, IN CUBIC FEET PER SECOND

Daily mean discharge, Johnson Creek

at Sycamore Road

Instantaneous discharge, Johnson Creek

at Palmblad Road

Suspended sediment, in milligrams per literDieldrin, in micrograms per literMetolachlor, in micrograms per literDDT + DDD + DDE, in micrograms per liter

CONCENTRATION 

Figure 17A. Response of flow and concentration of suspended sediment and three organic pesticides to the fiCreek during Phase II of the Willamette River Basin Water Quality Study, Oregon, 1994. (Daily mean dischargstation at Johnson Creek at Sycamore Road [river mile 10.2] is plotted to indicate the overall pattern of flow in Instantaneous discharge and constituent concentrations were measured on Johnson Creek at Palmblad Road 
45

LOAD

15 20 25 31 5 10 15 20 

October November

1994

0

900

100200300400500600700800

DISCHARGE IN CUBIC FEET PER SECOND

Daily mean discharge, Johnson Creek

at Sycamore gage

Instantaneous discharge, Johnson Creek

at Palmblad Road

Suspended sediment, in kilograms per dayDieldrin, in grams per dayMetolachlor, in grams per dayDDT + DDD + DDE, in grams per day

Figure 17B. Response of flow and loads of suspended sediment and three organic pesticides to the first fall storduring Phase II of the Willamette River Basin Water Quality Study, Oregon, 1994. (Daily mean discharge from thJohnson Creek at Sycamore Road [river mile 10.2] is plotted to indicate the overall pattern of flow in Johnson Crdischarge and constituent concentrations were measured on Johnson Creek at Palmblad Road [river mile 18.0].)
46

15 20 25 31 5 10 15 20 25 

October November

1994

0

130,000

10,00020,00030,00040,00050,00060,00070,00080,00090,000

100,000110,000120,000

DISCHARGE, IN CUBIC FEET PER SECOND

Estimated daily mean discharge,

Willamette River at Portland

Suspended sediment, in milligrams per liteAtrazine, in micrograms per literCarbofuran, when detected, in micrograms 

Metolachlor, in micrograms per liter

Carbofuran, not detected. The actual conce

is unknown but is less than 0.003 microg

CONCENTRATION 

Figure 18A. Response of flow and concentrations of suspended sediment and three organic pesticides to the firsRiver at Portland during Phase II of the Willamette River Basin Water Quality Study, Oregon, 1994. (Carbofuran wOctober 25 or December 1, 1994. The method detection limit for carbofuran is 0.003 micrograms per liter.)
47

LOAD B

15 20 25 31 5 10 15 20 25 30

October November 1994

0

130,000

10,00020,00030,00040,00050,00060,00070,00080,00090,000

100,000110,000120,000

DISCHARGE IN CUBIC FEET PER SECOND

Estimated daily mean discharge,Suspended sediment, in kilograms per dayAtrazine, in grams per dayCarbofuran, in grams per dayCarbofuran, not detected, in grams per day. The actual

Metolachlor, in grams per day

load, if any, was less than the amount shownWillamette River at Portland

Figure 18B. Response of flow and loads of suspended sediment and three organic pesticides to the first fall storms at Willametat Portland during Phase II of the Willamette River Basin Water Quality Study, Oregon, 1994. (Carbofuran was not detected on Oor December 1, 1994. The method detection limit for carbofuran is 0.003 micrograms per liter.)
48

simazine, have Koc values in the same range as metolachlor and tended to behave similarly at that site

(Harrison and others, 1995), albeit at different concentrations.

As stated, field observations indicated that sampling at Johnson Creek occurred at peak discharge

during the first and second major storms, on October

27 and November 1, 1994. However, several subsequent events of lesser magnitude were not sampled at

all, and the final sample, although it was taken as flow

was increasing, was collected during a relatively minor

storm. Thus a significant amount of data are not available regarding the response of the constituents examined during the duration of the runoff periods, and

quantitative determination of the overall transport of

these compounds and the contributions from individual storms cannot be made. Nonetheless, it appears

that the initial storms accounted for the highest

concentrations of most constituents and that concentrations declined overall during subsequent periods.

Consequently, the initial storms appear to have been

very important with respect to transport of contaminant loads in addition to causing high concentrations.

Correlations (using Kendall’s τ, with n=5)

between flow, concentrations of suspended sediment,

suspended organic carbon (SOC), and dissolved

organic carbon (DOC) with pesticide concentrations

were generally poor for the fall samplings at Johnson

Creek. Although suspended sediment concentration

was well correlated (p < 0.05) with DOC and SOC, it

was poorly correlated with instantaneous discharge

(p >0.1), as were DOC and SOC. DOC was well

correlated with concentrations of ΣDDX, atrazine,

metolachlor, and simazine, whereas correlations of

suspended sediment and SOC were significant

(p < 0.05) only with concentrations of atrazine.

It is somewhat surprising that ΣDDX, in particular, did not correlate well with suspended sediment or

SOC because ΣDDX is typically associated with sediments and sediment movement in streams. It is possible that the concentrations of DOC at Johnson Creek

(median = 3.9 mg/L) may have been high enough to

facilitate dissolution of DDX compounds into the dissolved phase or associations with colloidal forms of

organic carbon. However, correlations with SOC or

suspended sediment were not improved by subtracting

filtered water concentrations of p,p’-DDE, the most

soluble metabolite of DDT, from the unfiltered-water

concentration of ΣDDX. Other possible explanations

for the lack of correlation of ΣDDX with suspended

sediment and SOC concentrations include th

bility that the sediments sampled during the 

storms were from varying sources, such as b

ments and surface soils, and that sampling a

times on the hydrographs of the respective s

vided sediments of differing characteristics 

the overall mass sediment movement. This c

happened if the waters and sediments from t

on October 27 originated primarily within th

ambed, while saturation of the ground durin

storm provided more opportunities for soil e

from adjacent lands to contribute in greater 

tions during subsequent storms.

As was observed at Johnson Creek, the W

River at Portland appears to have experience

tial flush as a result of the first major storms 

of 1994 (figs. 18A and 18B). However, the p

flow and constituent runoff in the Willamett

was somewhat different from that at Johnson 

and reflects the considerable differences in b

and upstream land uses between the two site

differences and similarities are described be

Much of the land contributing to streamfl

Willamette River main stem at Portland incl

elevations in the Cascade Range which may 

tributed to increased flow and suspended sed

concentrations in the Willamette River durin

two storms. Rainfall was greater in the moun

in the Willamette Valley or Portland during 

from October 25–29 and October 31–Novem

storms (National Oceanic and Atmospheric 

tration, 1994). Rainfall was also greater in E

the southern part of the basin, than in Portla

the same two storms (fig. 4). A large storm i

of November and early December, which pro

highest flow in the Willamette River at Portla

the fall, began as rain on snow in the Cascad

tains (George Taylor, State Climatologist, or

mun., 1995), particularly in the northern par

basin, adding to the volume of water enterin

lamette from high elevations.

The source of the runoff to the Willamet

is important because water originating in the 

elevations is likely to be more dilute, and ca

pesticides, than water originating as agricult

urban runoff in the lower elevations of the v

Johnson Creek, like most of the agricultural 

sampled, originates in the lower elevations o

lamette River Basin and therefore, is not sub

runoff from high elevations. As a result, the 
49

flow in the Willamette River at Portland (figs. 18A and

18B) was somewhat different from that at Johnson

Creek (figs. 17A and 17B), especially after the storm

on October 31–November 2, when the entire Willamette River Basin, which by that time probably had

fully saturated soils, began to contribute runoff to the

main stem.

A sample collected on the Willamette River at

Portland on October 25, just prior to the initial flow

increases, had relatively low concentrations and loads

of dissolved pesticides (figs. 18A and 18B). As flow

increased and peaked during the first storm, the concentrations of suspended sediment and dissolved pesticides such as carbofuran, metolachlor, and atrazine all

increased. The concentrations and loads of suspended

sediment, atrazine, and metolachlor increased again by

the time of peak flow of the second storm, on November 3. This result is different from the observations at

Johnson Creek, when the highest concentrations were

found during the first major storm. In the Willamette

River, atrazine and metolachlor were not diluted by

the increased flow during the second storm, which

may be a result of contributions from the far upland

agricultural or urban areas of the basin; some of the

water may have even originated in the first storm, taking several days to make its way to the Portland site.

In contrast to atrazine and metolachlor, the concentration of carbofuran, which was not detected in the initial sampling prior to the storms, peaked during the

first storm and then decreased somewhat during the

second storm (fig. 18A). The load of carbofuran, however, remained essentially unchanged between the 1st

and 2nd storm samplings due to the increased flow

(fig. 18B).

The third major storm, at the end of November and

early December, produced rain-on-snow in the northern portions of the Cascades. The combination of

increased runoff from the rain on snow, together

with a general washing of constituents from soils

and riverbeds within the basin, appears to have

resulted in decreased concentrations of most constituents at the time of sampling compared to the storm of

October 30–November 2, despite the increased flow.

Carbofuran was again nondetectable at the MDL of

0.003 μg/L (fig. 18A). The instantaneous loads of atrazine and suspended sediment, however, were actually

greater during the final storm than previously, due to

the highly increased flow rates (fig. 18B).

An additional consideration is the effect of the

CSO system in Portland, which requires only a small

amount of rain (approximately 0.25 inches in one

storm) to become temporarily activated. When CSO

are discharging directly to the Willamette River, co

tact recreation is discouraged due to high bacterial 

els. While it is probable that there are additional

organic contaminants discharged to the river at the

times, it is uncertain to what extent these storms co

tribute to measured concentrations of pesticides or

other organic compounds in the Portland Harbor.

Other complicating factors include the large basin s

and heterogeneity of land uses contributing to the

water quality in the Willamette River at Portland. P

ticides in runoff, from the entirety of the diverse ag

cultural, urban, and forested land uses in the basin, 

integrated in the Willamette River by the time it

reaches the Portland site. In fact, the observations f

the Willamette River at Portland are interesting pri

rily with respect to the water quality at that site alo

they do not reveal much about the contributing fact

upstream because the linkages between sources an

observed water quality are poorly defined for such

large river sites.

As in the case of Johnson Creek, there are no d

available for the intervening periods between the

major storms, nor are there sufficient data to completely describe concentrations over individual stor

hydrographs in the Willamette River at Portland. A

of the qualifications about the data from Johnson

Creek apply equally to main-stem sites in the Willamette River. However, it is evident from figures 1

and 18B that high flows resulting from storm runof

resulted in the transport of a large amount of suspended sediments as well as dissolved pesticides.

SUMMARY AND CONCLUSIONS

This report presents results of sampling for trac

elements and organic compounds conducted by the

U.S. Geological Survey (USGS) as part of Phase II

of the Willamette River Basin Water Quality Study

USGS data from Phase I were included where cons

uents and media were common to both studies. Sam

ples were analyzed for trace elements in unfiltered

water (8 elements) and filtered water (17 elements)

volatile organic compounds in unfiltered water (63

compounds), organochlorine compounds in unfilter

and filtered water and suspended sediment (17 com

pounds), and pesticides in filtered water (94 compounds). During Phase I, 16 water samples were

collected from 11 sites between 1992 and 1993; dur
50

Phase II, 39 samples were collected from 32 sites during spring, 1994, and 39 samples were collected from

17 sites during fall, 1994. Overall, 94 water samples

were collected from a total of 40 sites between Phases

I and II. Data described in this report were compiled

by Harrison and others (1995).

Many potentially toxic trace elements and organic

compounds were detected in nonpoint source runoff in

the basin, in some cases exceeding State of Oregon

water-quality criteria or at otherwise high concentrations. However, no single overriding set of compounds or processes that water managers might

address to effect improvements in water-quality basinwide was apparent. Instead, there are a variety of

localized concerns, probably resulting from current or

historical land use practices, in both agricultural and

urbanized areas, that may require water managers to

consider site- or subbasin-specific measures to achieve

improvements in water quality. For instance, DDX

compounds (DDT, DDD, or DDE) were detected in

water at only 10 of the 40 sites sampled; however, all

detected concentrations exceeded the freshwater

aquatic life criterion for chronic toxicity and the criterion for protection of human life for water and fish

ingestion for those compounds. Several of these sites,

such as Johnson Creek at Palmblad Road or the I-84

runoff site, had concentrations of ΣDDX (the sum of

the concentrations of DDX compounds) that were very

high, indicating locations at which some form of best

management practices may be warranted. Likewise,

although concentrations of most of the 43 dissolved

pesticides detected (out of 61 documented as used)

were usually relatively low, numerous concentrations

that were potentially harmful to aquatic life were

observed at isolated sites. Several compounds (atrazine, simazine, metolachlor, and diuron) were

observed at almost all except forested sites. In general,

concentrations of organic compounds were at their

highest during stormflow, particularly during the first

major storms during the fall.

Dissolved pesticide concentrations in samples collected from larger streams, usually draining a mixture

of land uses, were generally lower than concentrations

observed in smaller drainages draining predominantly

agricultural or urban lands. It is expected that these

concentrations might be even higher at sampling locations farther upstream, closer to the contributing nonpoint source activities. However, for many of the trace

elements, pesticides, or other organic compounds

detected such as some volatile organic compounds

(VOCs), no water-quality criteria or guidelin

been established; nonetheless, there may be 

ous effects on aquatic organisms from these 

pounds. This may be particularly true at loc

where multiple compounds are found, some

high concentrations, that may act in concert 

ish the survival of aquatic organisms (Sprag

Thompkins, 1995; Yang, 1995). Furthermor

findings have suggested that some of the com

detected in this study, including DDX comp

atrazine, metribuzin, carbaryl, and 2,4-D, m

estrogen imitators, potentially hindering rep

success at a variety of levels within the food 

(Colborn and others, 1993). Although neithe

cology of mixtures of compounds, nor the is

estrogen imitators was investigated in this st

appropriate to consider these aspects when e

the data for toxicological impacts.

In samples from 26 sites, State of Orego

ter criteria for the protection of aquatic life (

chronic toxicity) and for the protection of hu

health were exceeded at 6, 11, and 7 sites, re

for trace elements in unfiltered water; urban 

the most exceedances. Lead exceeded the ac

ity criterion (ATC) or the chronic toxicity cr

(CTC) at nine sites, six of which were urban

which did not exceed any criteria at agricult

mixed land-use sites, exceeded both the ATC 

at five of nine urban sites. Comparisons to th

for cadmium, arsenic, lead, mercury, and sil

inconclusive at many sites because even the 

ratory reporting limits used in this study we

than the respective criteria. Sites with the gr

numbers of trace elements exceeding water-

criteria (6) included a site at Southeast 3rd A

Portland draining only Interstate Highway 8

from this site is discharged into the Willame

immediately downstream of the sampling lo

A-3 Channel at Wallis and Fifth Street in Eu

a large amount of industrial activity upstream 

site, also exceeded criteria for six trace elem

including mercury. Mercury was not sample

Interstate-84 runoff site in Portland.

In general, the highest trace-element con

trations were found at urban sites that receiv

part of their runoff from industrial sources. U

water trace-element concentrations of chrom

per, lead, nickel, and zinc correlated well (p

with suspended sediment concentrations at t

other urban sites. Unlike sites in the more re
51

basins, at which concentrations of some trace elements, most notably zinc and copper, appeared to

approach a maximum or even to decline as suspendedsediment concentrations increased, sites in industrial

basins continued to receive increasing trace-element

concentrations as suspended-sediment concentrations

increased. Whether the industrial source was enriched

due to higher trace-element concentrations in the

aqueous phase or in suspended sediment was not

directly assessed. However, an analysis of partitioning

of trace elements indicated that the greatest percentage

of trace elements was most likely associated with the

suspended phase.

Fourteen VOCs were detected at four locations

predominantly in commercial/industrial or residential

urban areas. Exceedances of the criterion for the protection of human health for water and fish ingestion,

cancer risk level 1 in 1 million (HHP) occurred for

benzene, chloroform, 1,1-dichloroethylene, and tetrachloroethylene. In addition, several other VOCs for

which water-quality criteria have not been established

were observed at relatively high concentrations

(greater than 1 μg/L).

Eight organochlorine (OC) compounds were

detected at 14 of the 40 sites sampled. Lindane, dieldrin, and DDX compounds were detected in roughly 30

percent of the samples, predominantly in the agricultural and urban areas. Polychlorinated biphenyl (PCB)

compounds were detected in samples from two urban

sites. All 19 samples (at 10 sites) in which DDX compounds were detected contained concentrations that

equaled or exceeded the CTC and the HHP. Eleven of

the 23 detected dieldrin concentrations from a mixture

of agricultural and urban areas exceeded the CTC

value, whereas all 23 of the detected dieldrin concentrations exceeded the HHP concentration. Only three

of the detected lindane concentrations from two agricultural sites and one heptachlor concentration from

an urban site exceeded their respective HHP values.

Six detected PCB concentrations from two urban sites

exceeded both the CTC and the HHP values.

Nine samples were analyzed for OCs in suspended

sediment and in filtered water to investigate partitioning. Only DDX compounds, which are considered to

be very hydrophobic, were detected consistently

enough in these samples to allow interpretation of

equilibrium conditions, and then only in four samples.

The largest percentage of the mass of ΣDDX was

found in suspended sediment, and in general these

compounds appeared to be near equilibrium between

the sediment and water phases. The relative fractio

of DDX compounds as DDT, DDD, and DDE were

similar to those found in other studies in Oregon an

Washington. In contrast, dieldrin and lindane, whic

are much more hydrophilic than DDX compounds,

were almost completely (greater than 99 percent)

present in the dissolved phase based on analyses in

unfiltered and filtered water.

Of the 94 dissolved pesticides analyzed, CTCs

were exceeded at only 1 site each for chlorpyrifos a

parathion, and at 2 sites for malathion. Diazinon, a

phos-methyl, carbaryl, and diuron each exceeded r

ommended threshold concentrations established in

1973 for the protection of aquatic life by the Natio

Academy of Sciences and the National Academy o

Engineering.

Between 80 and 90 percent of the water sample

collected had detectable concentrations of dissolve

atrazine, metolachlor, and simazine; between 40 an

61 percent of the samples collected had detectable

concentrations of desethylatrazine, cycloate, diazin

desisopropylatrazine, diuron, and hexazinone; and

roughly one out of every three samples contained

detectable concentrations of DCPA (dacthal), EPTC

and terbacil. A comparison made between the 25 m

frequently detected pesticides and 1987 estimates o

pesticide usage in the basin showed generally little

relation between the frequency of detection and do

mented pesticide usage, due in part to changes in b

pesticide usage and agricultural practices since the

1987 estimates were compiled. Other important fac

tors in the lack of agreement between observed pes

cide detections and usage estimates include chemic

or biological transformations in compounds in the

environment, partitioning between the dissolved an

suspended phases, variable hydrologic conditions

throughout the basin at the time of sampling, or the

ability of laboratory analytical procedures to detect

low concentrations of some compounds.

Several pesticides, including diazinon, prometo

and tebuthiuron, were detected primarily at urban

sites. Pesticides detected primarily or exclusively a

agricultural sites included carbofuran, EPTC, ethop

rop, fonofos, napropamide, and terbacil. Atrazine,

carbaryl, chlorpyrifos, DCPA, diuron, metolachlor,

and simazine were detected in similar percentages 

all except forested sites, although concentrations fo

most of these compounds tended to be higher at the

agricultural sites.
52

Atrazine, carbaryl, diuron, metolachlor, simazine,

and terbacil were detected in similar percentages in

both the northern and southern agricultural areas of the

basin. However, carbofuran, chlorpyrifos, DCPA,

diazinon, ethoprop, napropamide, and tebuthiuron

were detected only in the northern agricultural areas,

reflecting the diversity of agricultural crops grown

there. EPTC, fonofos, and prometon were detected in

both the northern and southern agricultural areas of the

basin, but usually in a larger percentage of the samples

in the northern agricultural area. In general, the frequency of detections for the most frequently detected

pesticides was slightly higher in fall than in spring

among the northern and southern agricultural sites

in the valley; the lone exception was carbaryl. More

frequent detections during the fall sampling period

may be an artifact of repeated sampling at some of the

fall sites. Because the fall sampling was performed

under higher flow and runoff conditions than the

spring sampling, however, the more frequent detections during the fall are also likely due to the higher

flow conditions.

Sixty-one of the 94 pesticides analyzed in filtered

water were reported to have been used in the basin in

1987; 43 of these were detected at least once during

1992–94. The median number of pesticides detected at

each sampling site was eight. Two agricultural sites,

Johnson Creek at Palmblad Road (near Gresham) and

Zollner Creek near Mount Angel, were the sites with

the greatest number of unique dissolved pesticides

observed (29 and 34, respectively).

Although the number of compounds detected at

each site was probably affected in part by unequal

sampling frequencies among the various sites, the

overall patterns of detections appear to reflect pesticide and land use in the basin. In general, the greatest

numbers of pesticides are found either at sites higher

up in tributary streams reflecting well define

sive land uses upstream (such as Zollner Cre

Johnson Creek, both of which are agricultur

streams), or at sites integrating a large variet

upstream land uses (such as the Tualatin Riv

Linn or the Willamette River at Portland). F

more, differences in the variety of agricultur

between the northern and southern portions 

lamette River Basin are reflected in the num

types of pesticides detected at northern and 

sites. Agricultural sites in the northern porti

basin tended to have a larger number of pest

detected than sites in the southern portions o

basin, including several such as carbofuran, 

fos, DCPA, diazinon, ethoprop, napropamid

tebuthiuron which were not detected at the s

sites.

Analytical results from repeated samplin

on Johnson Creek at Palmblad Road and in 

lamette River at Portland during sequential s

the fall of 1994 indicated that the first two m

storms that produced runoff at both sites res

relatively high instantaneous concentrations 

of several constituents when compared with 

quent storms. Suspended sediment, DDX co

metolachlor, and atrazine were at their highe

trations or loads during peak flows of the fir

Johnson Creek) or second (in the Willamette 

Portland) significant storms of the fall. Cont

weather and high flows effectively moved m

these compounds from their respective wate

that transport during subsequent storm cond

appeared to diminish. However, data were n

able to fully integrate concentrations over th

of the fall sampling period to completely ev

importance of specific storms in the transpo

organic compounds.
53

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———1993a, Willamette River Basin water qua

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———1993c, Reconnaissance survey of the low

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———1995, Willamette River Basin water qual

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55

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56
57

APPENDIXES
58
59

Appendix 1. Summary statistics for concentrations of selected trace elements detected in unfiltered and filtered water a

all sites during Phases I and II of the Willamette River Basin Water Quality Study, Oregon, 1992–94

[Statistics shown only for the detected concentrations; nondetects are not included; MRL, minimum reporting level; μg/L, micrograms per liter;

—, not applicable]

Element Medium

MRL (μg/L)

Numberof

detections

Number

of

samples

Detected concentrations (μg/L)

Phase I Phase II Minimum

25th

Percentile Median

75th

Percentile Maximu

Arsenic Filtered water 1 1 10 25 1 1 1.5 2 3

Arsenic Unfiltered

water 1 1 14 24 1 1 1 2 4

Aluminum Filtered water — 1 12 13 20 25 100 180 340

Antimony Filtered water 1 1 6 23 1 1 1.5 2 4

Barium Filtered water — 1 13 13 5 6 8 19 63

Beryllium Filtered water 10 1 0 25 — — — — —

Cadmium Filtered water .1 1 5 25 .1 .1 .2 .2 .7

Cadmium Unfiltered

water .5, 1 1 7 39 .1 1 2 2 7

Chromium Filtered water 1 1 9 25 .6 .9 1.8 2.5 5.4

Chromium Unfiltered

water .5,1 1 21 38 .6 2 5 7 16

Cobalt Filtered water .5 1 1 27 — — — — 3.2

Copper Filtered water .5 1 19 23 .7 1.3 2.2 7.4 21

Copper Unfiltered

water .5, 1 1 25 29 1 2.5 5 12 45

Lead Filtered water 1 1 9 25 .5 .7 2 2.3 4

Lead Unfiltered

water .5,1 1 23 39 .5 1 5 36 67

Mercury Filtered water .1 — 0 14 — — — — —

Mercury Unfiltered

water .1 .1 1 15 — — — — .1

Molybdenum Filtered water — 1 4 13 2 — 8.5 — 11

Nickel Filtered water 1 1 11 27 .6 1 2 4 7

Nickel Unfiltered

water 1 1 22 34 .8 2 3 8 12

Selenium Filtered water 1 1 0 27 — — — — —

Silver Filtered water 1 1 0 27 — — — — —

Uranium Filtered water — 1 0 11 — — — — —

Zinc Filtered water .5 1 15 25 .5 1.4 4 49 97

Zinc Unfiltered

water 10 10 24 39 .6 11 25 140 290
60

Appendix 2. Water-quality criteria used to calculate exceedances in water samples from Phase I and Phas

Willamette River Basin Water Quality Study, 1992–94

[Water-quality criteria are from Oregon Administrative Rules, Chapter 340, Division 41, 1994; For some trace elements, criteria conc

are calculated on the basis of hardness (hd) in milligrams per liter as CaCO3; the formulas for calculation of these criteria are given in 

hypothetical values; μg/L, micrograms per liter; —, no criteria; *, insufficient data to develop criteria; value presented is the lowest ob

effect level]

Constituent

Oregon freshwater criteria for aquatic toxicity

Oregon criterion for protection of h

health for water and fish ingestio

cancer risk 1 in 1 million (μg/L

Acute criterion

(μg/L)

Chronic criterion

(μg/L)

Trace elements

Arsenic — — 0.0022

Cadmium e(1.128[ln(hd)]-3.828) e(0.7852[ln(hd)]-3.49) 10

Chromium 16 11 50

Copper e(0.9422[ln(hd)]-1.464) e(0.8545[ln(hd)]-1.465) —

Lead e(1.273[ln(hd)]-1.46) e(1.273[ln(hd)]-4.705) 50

Mercury 2.4 .012 .144

Nickel e(0.8460[ln(hd)]+3.3612) e(0.8460[ln(hd)]+1.645) 13.4

Silver e(1.72[ln(hd)]-6.52) .12 50

Zinc e(0.8473[ln(hd)]+0.8604) e(0.8473[ln(hd)]+0.7614) —

Organochlorine compounds

DDT+DDE+DDD 1.1 .001 .000024

Dieldrin 2.5 .0019 .000071

Heptachlor .52 .0038 .00028

γ-HCH (Lindane) 2.0 .08 .0186

Methoxychlor — .03 100

PCBs 2.0 .014 .000079

Pesticides

2,4-D — — 100

2,4-dinitro-o-cresol — — 13.4

Chlorpyrifos .083 .041 —

Malathion — .1 —

Parathion .065 .013 —

Volatile and semivolatile organic compounds

Benzene *5,300 — .66

Chloroform *28,900 *1,240 .19

1,1-Dichloroethylene 11,600 — .033

Naphthalene *2,300 *620 —

Tetrachloroethylene *5,280 *840 .8

1,1,1-Trichloroethane — — 18,400

Trichloroethylene *45,000 *21,900 2.7

Toluene *17,500 — 14,300
61

Appendix 3. Summary statistics of concentrations of volatile organic compounds detected in unfiltered water at all sit

during Phases I and II of the Willamette River Basin Water Quality Study, Oregon, 1992–94

[Statistics shown only for the detected concentrations; nondetects are not included; MRL, minimum reporting level; μg/L, micrograms per liter;

— not applicable]

Analyte MRL

(μg/L)

Number of

detections

Number of

samples

Detected concentrations (μg/L)

Minimum 25th

Percentile Median 75thPercentile Maximum

Dichlorodifluoromethane 0.2 0 18 — — — — —

Chloromethane .2 0 18 — — — — —

Vinyl chloride .2 0 18 — — — — —

Bromomethane .2 0 18 — — — — —

Chloroethane .2 0 18 — — — — —

Trichlorofluoromethane .2 0 18 — — — — —

1,1-Dichloroethylene .2 3 18 0.2 — 0.3 — 0.3

Methylene chloride .2 3 18 .3 — .3 — .8

trans-1,2-Dichloroethylene .2 0 18 — — — — —

Methyl-tert-butyl ether (MTBE) 1 0 18 — — — — —

1,1-Dichloroethane .2 2 18 .2 — — — .4

2,2-Dichloropropane .2 0 18 — — — — —

Bromochloromethane .2 0 18 — — — — —

cis-1,2-Dichloroethylene .2 5 18 .3 .4 .6 .8 .9

Chloroform .2 3 18 .2 — .2 — .8

1,1,1-Trichloroethane .2 3 18 .7 — .8 — .9

Carbon tetrachloride .2 0 18 — — — — —

1,1-Dichloropropene .2 0 18 — — — — —

Benzene .2 3 18 .3 — 1 — 1.5

1,2-Dichloroethane .2 0 18 — — — — —

Trichloroethylene .2 4 18 .2 — .8 — 1.3

1,2-Dichloropropane .2 0 18 — — — — —

Bromodichloromethane .2 0 18 — — — — —

Dibromomethane .2 0 18 — — — — —

cis-1,3-Dichloropropene .2 0 18 — — — — —

Toluene .2 2 18 .2 — — — .7

trans-1,3-Dichloropropene .2 0 18 — — — — —

1,1,2-Trichloroethane .2 0 18 — — — — —

Tetrachloroethylene .2 5 18 .3 .4 .4 1.1 1.8

1,3-Dichloropropane .2 0 18 — — — — —

Dibromochloromethane .2 0 18 — — — — —

1,2-Dibromoethane (EDB) .2 0 18 — — — — —

Chlorobenzene .2 0 18 — — — — —

1,1,1,2-Tetrachloroethane .2 0 18 — — — — —

Ethylbenzene .2 0 18 — — — — —

Xylenes .2 2 18 .4 — — — .6

Styrene .2 0 18 — — — — —
62

Bromoform 0.2 0 18 — — — — 

Isopropylbenzene .2 0 18 — — — — 

1,1,2,2-Tetrachloroethane .2 0 18 — — — — 

Bromobenzene .2 0 18 — — — — 

1,2,3-Trichloropropane .2 0 18 — — — — 

n-Propylbenzene .2 0 18 — — — — 

2-Chlorotoluene .2 0 18 — — — — 

tert-Butylbenzene .2 0 18 — — — — 

Pseudocumene

(1,2,4-trimethylbenzene) .2 1 18 — — — — 

sec-Butylbenzene .2 0 18 — — — — 

p-Isopropyltoluene .2 0 18 — — — — 

1,3-Dichlorobenzene .2 0 18 — — — — 

1,4-Dichlorobenzene .2 0 18 — — — — 

n-Butylbenzene .2 0 18 — — — — 

1,2-Dichlorobenzene .2 0 18 — — — — 

1,2-Dibromo-3-chloropropane

(DBCP) 1 0 18 — — — — 

1,2,4-Trichlorobenzene .2 0 18 — — — — 

Hexachlorobutadiene .2 0 18 — — — — 

Naphthalene .2 1 18 — — — — 

1,2,3-Trichlorobenzene .2 0 18 — — — — 

p-Chlorotoluene .2 0 18 — — — — 

Trichlorotrifluoroethane .2 0 18 — — — — 

1,3,5-Trimethylbenzene .2 1 18 — — — — 

Acrolein 20 0 13 — — — — 

Acrylonitrile 20 0 13 — — — — 

2-Chloroethyl vinyl ether 1 0 13 — — — — 

Appendix 3. Summary statistics of concentrations of volatile organic compounds detected in unfiltered water 

during Phases I and II of the Willamette River Basin Water Quality Study, Oregon, 1992–94—Continued

[Statistics shown only for the detected concentrations; nondetects are not included; MRL, minimum reporting level; μg/L, micrograms p

— not applicable]

Analyte MRL

(μg/L)

Number of

detections

Number of

samples

Detected concentrations (μg/L)

Minimum 25th

Percentile Median 75thPercentile M
63

Appendix 4. Summary statistics of concentrations of organochlorine compounds from USGS schedules 1398 and 13

detected in unfiltered water at all sites during Phases I and II of the Willamette River Basin Water Quality Study, Orego

1992–94

[Statistics shown only for the detected concentrations; nondetects are not included; MRL, minimum reporting level; μg/L, micrograms per liter;

—, not applicable]

Compound

MRL (μg/L)

Number of

detections

Number of

samples

Detected concentrations (μg/L)

Phase I Phase II Minimum 25th

Percentile Median 75thPercentile Maximum

Aldrin 0.001 0.001 0 73 —————

Chlordane .1 .1 0 73 — — — — —

DDD .001 .001 8 73 0.001 0.001 0.001 0.002 0.002

DDE .001 .001 15 73 .001 .002 .002 .003 .030

DDT .001 .001 14 73 .001 .002 .002 .002 .030

Dieldrin .001 .001 23 73 .001 .001 .002 .005 .020

Endrin .001 .001 0 73 —————

Endosulfan .001 .001 3 73 .001 — .002 — .006

Heptachlor .001 .001 1 73 ———— .001

Heptachlor epoxide .001 .001 0 73 —————

Lindane .001 .001 23 73 .001 .001 .002 .006 .032

Methoxychlor .01 .01 0 73 — — — — —

Mirex .01 .01 0 73 — — — — —

PCBs .1 .1 6 73 .1 .1 .1 .2 .2

PCN .1 .1 0 73 — — — — —

Perthane .01 .1 0 73 — — — — —

Toxaphene 1.0 1.0 0 73 — — — — —
64

Appendix 5. Summary statistics of concentrations of pesticides from USGS schedules 2010 and 8015

detected in filtered water at all sites during Phases I and II of the Willamette River Basin Water Quality Study,

Oregon, 1992–94

[Statistics shown only for the detected concentrations; nondetects are not included; MDL, method detection limit; μg/L, micrograms pe

—, not applicable; (E), concentration is estimated]

Compound MDL

(μg/L)

Number of

detections

Number of

samples

Detected concentrations (μg/L)

Minimum 25th

Percentile Median 75thPercentile Max

Amide compounds

Alachlor 0.002 5 92 0.002 0.006 0.007 0.015 

Metolachlor .004 75 93 .003 .008 .026 .11 

Napropamide .004 27 93 .004 .014 .033 .097 

Pronamide .018 18 93 .004 .006 .012 .022 

Propachlor .007 3 93 .004 — .009 — 

Propanil .004 2 93 .003 — — — 

Carbamate compounds

Butylate .002 0 93 ————

Carbaryl (E).003 21 93 .003 .006 .010 .026 

Carbofuran (E).003 21 93 .009 .035 .11 .36 

EPTC .002 29 93 .001 .005 .008 .021 

Molinate .003 0 93 ————

Pebulate .004 1 93 ———— 

Thiobencarb .002 0 93 ————

Triallate .001 6 93 .002 .002 .007 .01 

Dinitroaniline compounds

Benfluralin .002 1 93 ———— 

Ethalfluralin .004 0 93 ————

Pendimethalin .004 3 93 .011 — .014 — 

Trifluralin .002 16 93 .003 .005 .006 .0095 

Miscellaneous compounds

2,6-Diethylaniline .003 0 93 ————

Propargite .013 3 93 .003 — .010 — 

Organochlorine compounds

DCPA .002 32 93 .001 .002 .004 .007 

Dieldrin .001 5 93 .007 .012 .016 .019 

p,p’-DDE .006 9 93 .001 .002 .003 .003 

alpha-HCH .002 0 93 ————

Lindane

(gamma-HCH) .004 5 93 .004 .005 .021 .03 

Organophosphorus compounds

Chlorpyrifos .004 24 93 .002 .007 .010 .023 

Diazinon .002 44 93 .002 .006 .015 .03 

Disulfoton .017 0 93 ————

Ethoprop .003 24 93 .002 .005 .011 .088 

Fonofos .003 24 92 .001 .004 .012 .03 

Malathion .005 8 93 .009 .013 .020 .066 

Methyl Azinphos (E).001 1 90 — — — — 

Methyl Parathion .002 0 93 ————

Parathion .006 0 93 ————

Phorate .002 0 93 ————
65

Terbufos 0.007 0 93 —————

Permethrin compounds

cis-Permethrin .005 0 93 —————

Phenyl Urea compounds

Linuron .002 1 93 — — — — 0.78

Tebuthiuron .01 21 93 0.003 0.007 0.032 0.052 .12

Triazine compounds

Atrazine .001 84 93 .005 .023 .052 .18 2.7

Cyanazine .004 0 93 —————

Desethylatrazine (E).002 56 93 .002 .005 .010 .021 .27

Metribuzin .004 19 93 .006 .011 .038 .064 .41

Prometon .003 27 93 .005 .008 .013 .026 .068

Simazine .005 76 93 .004 .026 .095 .2 3.5

Uracil compounds

Terbacil (E).007 34 90 .006 .011 .027 .073 1

Pesticides by custom low-level analyses (USGS schedule 8015)

Ametryn .006 0 58 —————

Butachlor .008 0 58 —————

Cycloate .01 25 58 .001 .002 .002 .003 .020

Desisopropylatrazine .004 23 58 .002 .002 .004 .008 .023

Hexazinone .013 28 58 .001 .002 .003 .006 .040

Prometryn .007 0 58 —————

Propazine .006 0 58 —————

Simetryn .005 0 58 —————

Appendix 5. Summary statistics of concentrations of pesticides from USGS schedules 2010 and 8015

detected in filtered water at all sites during Phases I and II of the Willamette River Basin Water Quality Study,

Oregon, 1992–94—Continued

[Statistics shown only for the detected concentrations; nondetects are not included; MDL, method detection limit; μg/L, micrograms per liter;

—, not applicable; (E), concentration is estimated]

Compound MDL

(μg/L)

Number of

detections

Number of

samples

Detected concentrations (μg/L)

Minimum 25th

Percentile Median 75thPercentile Maximum
66

Appendix 6. Summary statistics of concentrations of pesticides from USGS schedule 2051 detected in

filtered water at all sites during Phases I and II of the Willamette River Basin Water Quality Study, Oregon,

1992–94

[Statistics shown only for the detected concentrations; nondetects are not included; minimum reporting level for all compounds is 0.

micrograms per liter (μg/L); —, not applicable; (E), concentration is estimated; on the basis of results from replicate and spike recov

samples, many compounds had lower than average accuracy and precision from 1993–94 (Werner and others, 1996, Appendix B)]

Compound Number of

detections

Number of

samples

Detected concentrations (μg/L)

Minimum

25th

Percentile Median

75th

Percentile Maxim

Benzoic acid compounds

Dicamba 1 82 — — — — 0.0

Benzonitrile compounds

Bromoxynil 1 82 — — — — .11

Dichlobenil (E) 1 81 — — — — .42

Carbamate compounds

Aldicarb 0 81 — — — — —

Aldicarb Sulfone 0 81 — — — — —

Aldicarb Sulfoxide 0 81 — — — — —

Carbaryl 2 81 .07 — — — .2

Carbofuran 4 81 .05 — .29 — .4

3-Hydroxy-carbofuran 0 81 — — — — —

Methiocarb 0 81 — — — — —

Methomyl 0 81 — — — — —

Oxamyl 1 81 — — — — .07

Propham 0 81 — — — — —

Propoxur 0 80 — — — — —

Chlorophenoxy acid compounds

Bentazon 3 82 .08 — .26 — .41

2,4-D 10 84 .05 .08 .18 .23 .79

2,4-DB 0 82 — — — — —

Dacthal-mono-acid 0 82 — — — — —

Dichloroprop (2,4-DP) 0 82 — — — — —

MCPA 1 82 — — — — .09

MCPB 0 82 — — — — —

Silvex (2,4,5-TP) 0 84 — — — — —

2,4,5-T 0 84 — — — — —

Dinitroaniline compounds

Oryzalin 1 81 — — — — .23

Dinitrophenol compounds

Dinoseb (DNBP) 4 82 .06 — .075 — .23

Dinitrophenyl compounds

2,6-Dinitro-o-cresol (DNOC) (E) 1 82 — — — — .05

Diphenyl ether compounds

Acifluorfen 0 82 — — — — —

Naphthol compounds

1-Naphthol (E) 0 81 — — — — —

Phenoxy acid compounds
67

Chloramben (Aimben) 0 81 — — — — —

Phenyl urea compounds

Diuron 44 81 0.05 0.11 0.32 0.95 9

Fenuron 0 81 — — — — —

Fluometuron 0 81 — — — — —

Linuron 0 81 — — — — —

Neburon 0 81 — — — — —

Phthalimide compounds

Chlorothalonil (E) 0 81 — — — — —

Pyrethroid compounds

Esfenvalerate (E) 0 81 — — — — —

Pyridazinone compounds

Norflurazon 0 81 — — — — —

Pyridine compounds

Clopyralid 0 82 — — — — —

Picloram 0 82 — — — — —

Pyridyloxyacetic acid compounds

Triclopyr 11 82 .05 .11 .18 .44 .72

Uracil compounds

Bromacil 1 83 — — — — .2

Appendix 6. Summary statistics of concentrations of pesticides from USGS schedule 2051 detected in

filtered water at all sites during Phases I and II of the Willamette River Basin Water Quality Study, Oregon,

1992–94—Continued

[Statistics shown only for the detected concentrations; nondetects are not included; minimum reporting level for all compounds is 0.05

micrograms per liter (μg/L); —, not applicable; (E), concentration is estimated; on the basis of results from replicate and spike recovery

samples, many compounds had lower than average accuracy and precision from 1993–94 (Werner and others, 1996, Appendix B)]

Compound Number of

detections

Number of

samples

Detected concentrations (μg/L)

Minimum

25th

Percentile Median

75th

Percentile Maximum
68

Appendix 7. Explanation of calculations for theoretical equilibrium partitioning of DDT and metabolite compound

The theoretical equilibrium fraction of organic compounds present in the suspended phase was calcul

the individual organic carbon-water partitioning value (Koc) for the compound, as well as the suspended o

carbon (SOC) concentration, using the equation:

where:

Xs = equilibrium mass fraction of organic compound in the suspended phase,

[SOC] = concentration of suspended organic carbon, in mg/L, and

Koc = organic carbon-water partitioning coefficient for that compound, in mL/g.

For DDX compounds (DDT, DDD, or DDE), the calculated Xs for each compound was multiplied by 

the amounts observed in the dissolved and suspended phases in the sample, and summed to yield the equi

ΣDDX (sum of the individual DDX compound concentrations) in the suspended phase. Dividing this con

by the combined ΣDDX observed in the dissolved and suspended phases in the sample gives the equilibriu

of DDX compounds present in the suspended phase. As an estimate of the state of equilibrium of DDX com

the water at the time of sampling, the equilibrium suspended fraction was compared to the observed susp

fraction; these two fractions are shown for four water samples in figure 10.

As an example, consider the sample from Johnson Creek on October 27, 1994 (table 7–1). The observ

of DDX compounds in the suspended phase (0.057/0.064) is 0.89, whereas the equilibrium fraction (0.048

is 0.75.

 Table 7-1. Example computation of the partitioning of DDT and metabolite compounds in the suspended pha

Johnson Creek at Palmblad Road, October 27, 1994

[Suspended organic carbon (SOC) concentration = 5.7 milligrams per liter; sediment water partitioning coefficients (Koc) are taken fro

Environmental Protection Agency (1990); mL/g, milliliters per gram; Xs, expected fraction in suspended phase, at equilibrium; μg/L, m

per liter]

Compound

Koc

(mL/g) Xs

Concentration of DDT compounds (μg/L)

Observed,

dissolved phase

Observed,

suspended phase

Sum of dissolved and

suspended phases

Suspended p

at equilibri

DDD 770,000 0.81 0.001 0.006 0.007 0.006

DDE 4,400,000 .96 .003 .020 .023 .022

DDT 243,000 .58 .003 .031 .034 .020

Sum: — — .007 .057 .064 .048

Xs

1

106

[ ] SOC Koc ⋅ ] --------------------------------     + 1

= -----------------------------------------------------