1
 

Cover.—Left, Agricultural land in the upper Johnson Creek Basin, Right, Pasture and recent urban development in the middle Johnson Creek Basin,

Bottom, Johnson Creek 1 mile above its confluence with the Willamette River.
Organochlorine Pesticides in the Johnson Creek Basin, 

Oregon, 1988–2002

By Dwight Q. Tanner and Karl K. Lee 

U.S. Department of the Interior

U.S. Geological Survey

Prepared in cooperation with 

the City of Portland,

the City of Gresham,

the City of Milwaukie,

Clackamas County, and

Multnomah County

Scientific Investigations Report 2004–5061
U.S. Department of the Interior

Gale A. Norton, Secretary

U.S. Geological Survey

Charles G. Groat, Director

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

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

Box 25286, Denver Federal Center

Denver, CO 80225

For more information about the USGS and its products:

Telephone: 1-888-ASK-USGS

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

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

endorsement by the U.S. Government.

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

contained within this report.

Suggested citation: 

Tanner, D.Q., and Lee, K.K., 2004, Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002: U.S. Geological Survey Scientific 

Investigations Report 2004–5061, 36 p.
 iii

Contents

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

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

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2

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

Study Area Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Study Design and Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Hydrologic Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Sample Collection and Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Quality Assurance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Hydrologic Conditions during Storm Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Occurrence of Organochlorine Pesticides and Compliance with Criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

Loads of Organochlorine Pesticides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Total DDT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Dieldrin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Relation of Total Suspended Solids to Turbidity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Relation of Organochlorine Pesticides to Total Suspended Solids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Organochlorine Pesticides in Kelley Creek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Implications for Future Study. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Summary and Conclusions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

References Cited . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

Figures

 Figure 1. Map of sampling locations, Johnson Creek Basin, Oregon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

 Figure 2. Map of land cover categories, Johnson Creek Basin, Oregon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6

 Figure 3. Stream hydrographs, times of sample collection, and precipitation, Johnson Creek Basin, 

Oregon, March 11–13, 2002. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

Figure 4. Graph showing surrogate recoveries by the USGS laboratory, samples of Johnson Creek Basin, Oregon, 

March 2002 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Figure 5. Stream hydrograph of Johnson Creek at Milwaukie, Oregon, October 2001 through March 2002 . . . . . . . . . . . . . . . . . . . . . .15

Figure 6. Graph showing discharge at storm drains, times of sample collection, and precipitation, Johnson Creek Basin, 

Oregon, March 11, 2002 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

 Figure7. Graph showing the relation between the concentrations of total DDT and dieldrin, Johnson Creek Basin, Oregon,

2001–02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

 Figure 8. Graph showing potential exceedances of Oregon water quality criteria, Johnson Creek Basin, Oregon, 

2001–02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

 Figure 9. Graphs showing total DDT loads and streamflow hydrographs, Johnson Creek Basin, Oregon, March 11–13, 

2002. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

Figure 10. Graphs showing dieldrin loads and streamflow hydrographs, Johnson Creek Basin, Oregon, March 11–13, 2002. . . . . .25

Figure 11. Graph showing the relation between total suspended solids and turbidity, Johnson Creek and Kelley Creek,

Oregon, 2001–03. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
iv 

Figure 12. Graphs showing the relation between total DDT and total suspended solids, Johnson Creek Basin, Oregon, 

1989–2002. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Figure 13. Graph showing daily mean discharge and discharge at time of sampling at Kelley Creek, Oregon, and 

daily total precipitation, October 2001 to January 2003 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Figure 14. Graph showing the relation between p,p’-DDE + p,p’-DDD concentration and total suspended solids,

Kelley Creek, Oregon, 1989–90 and 2001–03. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Tables

Table 1. Sampling sites and data sources for organochlorine compounds, Johnson Creek Basin, Oregon, 1988–2002 . . . . . . . . . . . 5

Table 2. Drainage area and land cover for sampling sites, Johnson Creek Basin, Oregon, 1988–2002 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Table 3. Organochlorine compounds analyzed in unfiltered water samples, Johnson Creek Basin, Oregon, 2002, and

Oregon water quality criteria. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Table 4. Quality control data for the U.S Geological Survey and Oregon Department of Environmental Quality laboratories, 

Johnson Creek Basin, March 10–13, 2002. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Table 5. Summary of spike recoveries, U.S. Geological Survey and Oregon Department of Environmental Quality

laboratories, Johnson Creek Basin, March 10–13, 2002. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Table 6. Organochlorine-compound and streamflow data, Johnson Creek Basin, Oregon, March 11–13, 2002. . . . . . . . . . . . . . . . . . 18

Table 7. Organochlorine-compound and streamflow data collected and analyzed by Oregon Department of 

Environmental Quality, Johnson Creek Basin, Oregon, 2001–02. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Table 8. Organochlorine-compound, streamflow and turbidity data, Johnson Creek Basin, Oregon, 1989–90 . . . . . . . . . . . . . . . . . . . 22

Table 9. Organochlorine-compound and other water-quality data collected and analyzed by the City of Portland, Oregon, 

Kelley Creek, 2002–03. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Table 10. Maximum concentration of total suspended solids associated with the exceedance of the water-quality 

criterion for total DDT, Johnson Creek Basin, Oregon. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Conversion Factors

Multiply By To obtain

 Length

micrometer (μm) 0.00003937 inch (in)

 Mass

microgram (μg) 0.00000003527 ounce (oz avoirdupois)

milligram (mg) 0.00003527 ounce

gram (g) 0.03527 ounce

Concentration, By Volume

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

milligrams per liter (mg/L) 1 parts per million (ppm)
Organochlorine Pesticides in the Johnson Creek Basin, 

Oregon, 1988–2002

By Dwight Q. Tanner and Karl K. Lee

Abstract

Organochlorine pesticides were detected in 

unfiltered samples from Johnson Creek that were collected during a storm in March, 2002. Total DDT (the 

sum of DDT and its metabolites), as well as dieldrin, 

potentially exceeded Oregon chronic, freshwater 

criteria at all four Johnson Creek stream-sampling 

sites. The total DDT criterion was also potentially 

exceeded at a storm drain at SE 45th Avenue and 

Umatilla Street. 

The concentration of total DDT in water samples has decreased by an order of magnitude since 

previous sampling was done on Johnson Creek in 

1989–1990. This decrease was probably due to the 

movement of these compounds out of the basin and 

to degradation processes. Concentrations and loads 

of the organochlorine pesticides were largest at the 

most upstream sampling site, Johnson Creek at Palmblad Road, which has historically been primarily 

affected by agricultural land cover. Concentrations 

and loads were smaller at downstream locations, and 

there were only a few detections from storm drains. 

For the purposes of assessing trends in total 

DDT concentration in Johnson Creek, data for total 

suspended solids (TSS) were examined, because TSS 

is often correlated with DDT concentrations, and 

TSS data are collected routinely by regulatory agencies. As an intermediate step, linear regression was 

used to relate TSS (measured in the recent study) and 

turbidity (measured both in the earlier and in the 

recent studies). For 77 samples, TSS (in mg/L [milligrams per liter]) = 0.88 x Turbidity (in nephleometric 

turbidity units). The r2 value was 0.82. 

The TSS concentration (measured, or estimated by the regression) was compared to the concentration of total DDT using linear regression. The 

TSS concentration associated with meeting the Oregon water-quality criterion for total DDT was 15 to 

18 mg/L in the lower and middle part of the basin and 

8 mg/L in the upper reaches of the basin. This TSS/

DDT relationship is based on only one storm and 

may not be valid for other conditions of streamflow 

and runoff. Dieldrin concentration was not well correlated with TSS. 

Organochlorine compounds also were detected 

in significant concentrations in Kelley Creek, an 

important tributary to Johnson Creek, but qualitycontrol considerations made it difficult to interpret 

some of the data. It does appear, however, that some 

of the metabolites of DDT were positively associated 

with TSS. The high concentrations of the DDT 

metabolites and dieldrin were correlated with agricultural areas.

Introduction

Johnson Creek is a free-flowing stream in the Portland metropolitan area that has historically supported 

native fish populations, but it has a recent history of high 

pesticide concentrations (mostly organochlorine compounds), both in the water column and in streambed sediments. The U.S. Geological Survey (USGS), in cooperation with local jurisdictions, began an assessment of the 

hydrologic conditions in the Johnson Creek Basin and in 

March 2002 sampled Johnson Creek and storm drains for 

organochlorine compounds. In addition to the March 2002 

sampling, samples were taken at several other sites in the 

basin by other agencies.
2 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002

Background

Unfiltered stream samples were collected during 

storms in 1989 and 1990 at multiple sites in the Johnson 

Creek Basin. These samples contained high total dichlorodiphenyltrichloroethane (DDT) as well as high dieldrin 

concentrations. (In this report, the term “total DDT” means 

the sum of the concentrations of DDT and its metabolites, 

dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD). Likewise, the term “DDX” refers 

generally to the occurrence of any combination of the DDT 

compounds and their metabolites.) The highest concentrations of total DDT from Johnson Creek samples for both 

the December 1989 and January 1990 storms were from 

the site at Regner Road at river mile (RM) 15.8 (fig. 1), 

where the peak concentrations were 0.86 μg/L (micrograms per liter) and 0.255 μg/L, respectively. The highest 

dieldrin concentrations were also at the Regner Road site, 

where the concentrations during the same two storms were 

0.060 μg/L and 0.035 μg/L. DDX, as well as lindane and 

dieldrin, were detected at low concentrations in a storm 

drain (outfall) at SE 100th and Knapp during the January 

1990 storm (Edwards, 1992). 

Organochlorine compounds also were detected in 

unfiltered samples from Johnson Creek at Palmblad (RM 

17.2) in 1994 (Harrison and others, 1995). In the 1994 

study, of the 33 sites in the Willamette River Basin where 

pesticide analyses were done, total DDT and dieldrin were 

detected most frequently at Johnson Creek at Palmblad 

Road, with maximum concentrations of both compounds 

of about 0.02 μg/L. 

DDT also has been detected in streambed sediments. 

Samples taken during low flow in August 1988 at nine 

sites on Johnson Creek indicated that the largest concentration of total DDT was at the most upstream sample site, 

Hogan Road, at RM 17.4 (Edwards and Curtiss, 1993). In 

a 1992 study of 14 sites in the Willamette River Basin, 

streambed sediment at the Hogan Road site had the highest 

concentrations of total DDT and dieldrin (Harrison and 

others, 1995).

Semipermeable membrane devices (SPMDs) were 

used in a study of the Lower Columbia River Basin 

(McCarthy and Gale, 1999), which included one site on 

Johnson Creek. The purpose of this study was to better 

understand the partitioning of organic compounds into lipids, as occurs in aquatic organisms. Levels of several organochlorine compounds, including DDX and dieldrin, were 

somewhat elevated in the SPMDs in 1997 and 1998 at the 

sampling site on Johnson Creek at Milwaukie (RM 0.7) 

compared to other sites in the Lower Columbia River 

Basin.

The organochlorine compounds DDT and dieldrin 

were some of the first organic pesticides developed. Their 

production has decreased because their use has become 

regulated or banned in the United States. The agricultural 

uses of chlordane, DDT, and dieldrin were banned in the 

early 1970s (U.S. Environmental Protection Agency, 

1985), but chlordane was used for termite control until the 

late 1980s. Although there are no records to indicate the 

usage of these pesticides in the Johnson Creek Basin, 

annual use in the United States peaked in the mid-1960s 

for DDT (70,000 tons) and for aldrin/dieldrin (9,000 tons) 

(Smith and others, 1988, p. 27). Organochlorine compounds in general have a low solubility in water and a high 

environmental persistence (Witkowski and others, 1987). 

Polychlorinated biphenyls (PCBs) are synthetic compounds that were widely used in electrical transformers in 

the 1960s and 1970s, but were banned in 1979. PCBs are 

almost insoluble in water and persist in the environment, 

so they can become concentrated in suspended-sediment 

particles.

Johnson Creek, one of the few free-flowing streams 

in the Portland metropolitan area, is a significant resource 

(Woodward-Clyde, 1995) and is the subject of a number of 

protective measures. Chinook salmon and steelhead, listed 

as protected under the Endangered Species Act, inhabit the 

creek. Johnson Creek was included in the State of Oregon, 

Department of Environmental Quality (ODEQ), 303(d) 

List of Impaired Waters in 1998 for DDT, dieldrin, fecal 

coliform bacteria, and temperature. In 2002, PCBs and 

polycyclic aromatic hydrocarbons were added to the 

303(d) list (Oregon Department of Environmental Quality, 

2003a). The ODEQ is in the process of developing Total 

Maximum Daily Load (TMDL) allocations for total DDT, 

dieldrin, temperature, and bacteria.

Purpose and Scope

In 1998, the U.S. Geological Survey (USGS) entered 

into a cooperative study with the City of Portland, Bureau 

of Environmental Services, to study hydrologic conditions 

in the Johnson Creek Basin. The primary focus of the original study was to better understand ground-water-caused 

flooding problems in the basin and to provide streamflow 

and water-quality data that would be of use to the public 

and to resource managers. The study was expanded in subsequent years to include support from the Cities of Gresham and Milwaukie, and Clackamas and Multnomah 

Counties. Monitoring of the quantity and quality of surface 

water and ground water has led to a better understanding 

of the hydrology in the basin. The study was further 

expanded in 2002 to include intensive sampling for specific water-quality parameters to provide additional data 

for development of TMDLs for total DDT, dieldrin, and 

bacteria in the basin. 

This report contains previously unreported organochlorine-pesticide data from four stream sites and two 

storm drains, all sampled during a storm from March 11 to 

March 13, 2002. These results are compared with those 

from other organochlorine-compound samplings over the 

past decade. The interpretations of these data were used to 
Figure 1. Sampling locations, Johnson Creek Basin, Oregon. RM, river mile.
4 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002

help determine the movement and trends of organochlorine 

compounds in the basin and how their occurrence relates to 

total suspended solids (TSS), land use, and to possible 

source areas.

In addition to the March 2002 sampling, samples 

were taken at several other sites on both Johnson Creek 

and Kelley Creek (a tributary to Johnson Creek) by other 

agencies. Samples were taken from Johnson Creek from 

November 2001 to January 2002 by the ODEQ and from 

Kelley Creek from January 2002 to January 2003 by the 

City of Portland. Both the ODEQ and City of Portland data 

are used in this report to provide nonstorm organochlorinecompound data to be used in conjunction with the storm 

samples taken by the USGS.

Study Area Description

The Johnson Creek Basin is located in northwest 

Oregon in Clackamas and Multnomah Counties (fig. 1). 

Johnson Creek flows through the cities of Gresham, Portland and Milwaukie, where it flows into the Willamette 

River. The creek is about 24 miles long and drains an area 

of 54 square miles. The headwaters as well as the several 

tributaries on the south side of the basin originate in a 

group of volcanic hills (Trimble, 1963). The largest southside tributary is Kelley Creek. Few tributaries flow into 

Johnson Creek from the relatively flat area north of 

Johnson Creek because of permeable deposits left by the 

Missoula Floods after the last Ice Age (Waitt, 1985). The 

primary north-side tributary is Crystal Springs Creek. The 

relatively high and constant flow of Crystal Springs Creek 

is indicative of regional ground-water discharge. Being in 

a rapidly-developing urban area, Johnson Creek has been 

adversely affected by urbanization (Laenen, 1980). Channel simplification, rock lining of the stream channel, establishment of a network of storm drains, and paving of oncepervious areas may have affected both runoff volume and 

response to precipitation events. Urban development in 

recent years has resulted in the conversion of agricultural 

lands to residential uses, particularly in the southern and 

eastern part of the Johnson Creek Basin.

Acknowledgments

The authors thank the following members of the 

Johnson Creek Interjurisdictional Committee (monitoring 

subgroup) for aid in site selection, for guiding this report, 

and for funding:

Frank Wildensee City of Portland

Lynne Kennedy City of Gresham

Ruthanne Bennett City of Milwaukie

Andrew Swanson Clackamas County

Kim Peoples Multnomah County

Chauncey Anderson (USGS) organized the field 

crews for the March 2002 sampling and designed the quality-assurance measures. Water-quality sampling assistance was received from Heather Bragg and Amy Brooks 

of the USGS, and Anna Buckley (formerly of the USGS). 

Greg Geist (ODEQ) provided data and technical review. 

Peter Abrams of City of Portland Water Quality Laboratory and Barb Adkins of the City of Gresham provided 

flow data and access to the storm drain sites.

Study Design and Methods

Johnson Creek was sampled by the USGS and other 

agencies from 1988 to 2002 (table 1, fig. 1). In addition to 

the sites shown in table 1, the City of Portland took samples on Kelley Creek at RM 2.5, 1.2, 0.5, 0.0 and on Clatsop Creek (a tributary to Kelley Creek). Several of the sites 

on Johnson Creek sampled in 2001–02 had been sampled 

in previous studies, making it possible to compare data 

trends over time.

Land cover data were used to characterize the contributing area to the sampling sites in the Johnson Creek 

Basin (fig. 2, table 2). Data for land cover, which reflects 

land use, were obtained from the Metro Data Resource 

Center, Portland, Oregon (Steve Erickson, written commun., 2003). The land cover data were published in 1998, 

and were the result of updating 1992 land cover data based 

on 1998 Landsat Thematic Mapper imagery, aerial photography and digital orthophotos. The 1998 land cover used 

the same classification scheme as the previous edition. The 

16 classifications were barren/sparsely vegetated, 2 agricultural types, 9 forest types, 3 shrub types, and meadow/

grass. These classifications were grouped for this study 

into five classifications: (1) barren/sparsely vegetated 

(referred to as “urban” in this report), (2) agricultural, (3) 

closed-canopy forest, (4) scattered and open-canopy forest 

and shrub, and (5) meadow and grass. The land-cover data 

were used to relate spatial differences in organochlorine 

compounds in the basin to the vegetation types. Present 

land cover is not expected to be the same as land cover 

decades ago when organochlorine compounds discussed in 

this report were in use, but recovery of historical land use/

land cover data (if it exists) was beyond the scope of this 

report. 

Hydrologic Data

Stream discharge data used in this study were from 

the following USGS gaging stations: Johnson Creek at 

Regner Road (station 14211400), Johnson Creek at 

Sycamore (station 14211500), Johnson Creek at Milwaukie (station 14211550), and Kelley Creek at 159th 

Drive, (station 14211499), (fig. 1, table 1). Daily streamflow data for the 2002 water year were published by the 
Table 1. Sampling sites and data sources for organochlorine compounds, Johnson Creek Basin, Oregon, 1988–2002. 

[Sample media are unfiltered water, unless otherwise specified. Map ID refers to the number on figure 1. Abbreviations: USGS, U.S. Geological Survey; 

ODEQ, Oregon Department of Environmental Quality; N/A, not applicable; SPMD, semipermeable membrane device; QA, quality assurance; SED, in 

addition to a water sample, a streambed sediment sample was collected in low-flow conditions of 1988. Source: (1) Harrison and others, 1995; (2) Oregon Department of Environmental Quality; (3) This publication; (4) Edwards, 1992; (5) McCarthy and Gale, 1999]

Map ID Site Name USGS site number

Johnson 

Creek river 

mile

Dates 

sampled

Sampling 

agency Sample type Source

1 Johnson Creek at Palmblad Road 452823122240900 17.2 1994

2001

2002

USGS

ODEQ

USGS

spring and fall

winter

storm

(1)

(2)

(3)

2 Johnson Creek at Regner Road 452910122251500 15.8 1989/90 USGS storms (4)

4 Johnson Creek at SE 190th Avenue N/A 12.6 2001/02 ODEQ winter (2)

9 Kelley Creek at SE 159th Drive 14211499 10.6 1989/90 USGS storms (4)

10 Johnson Creek at Sycamore 14211500 10.2 1989/90

2002

USGS

USGS

storms

storm

(4)

(3)

11 Johnson Creek at SE 92nd Avenue 452806122340300 5.8 1988

2001/02

USGS

ODEQ

SED only 

storm

(4) 

12 Johnson Creek at SE 82nd Avenue 452717122344000 5.5 1989/90 USGS SED (4)

13 Johnson Creek at SE Stanley Avenue 452722122361100 3.6 1989/90 USGS storms (4)

14 Johnson Creek at SE 45th Avenue 452743122365400 3.2 2001/02

2002

ODEQ

USGS

storm, QA

storm

(2)

(3)

15 Johnson Creek at SE 44th Avenue 

between Umatilla Avenue and Tenino

452750122370000 3.0 1990 USGS SED (4)

17 Johnson Creek at Milwaukie 14211550 0.7 1989/90

1997

1998

2002

USGS

USGS

USGS

USGS

storms

SPMD, low flow

SPMD, high flow

storm

(4)

(5)

(5)

(3)

18 Johnson Creek at SE 17th Avenue N/A 0.3 2001/02 ODEQ storm (2)

3 Storm Drain in Gresham City Park 452951122254600 N/A 2002 USGS storm (3)

16 Storm Drain at SE 45th Avenue and 

Umatilla Street

452750122365300 N/A 2002 USGS storm (3)

Study Design and Methods 5

U.S. Geological Survey (2003). Discharge was determined 

for the Palmblad Road and 45th Avenue sites by 

developing a temporary stream-stage/discharge rating 

during the winter of 2001–02 (methods described in Rantz 

and others, 1982). Water-surface elevation observations 

were associated with discharge measurements (U.S. 

Geological Survey, 2003) to develop a rating for each site. 

During the storm of March 2002, the water-surface 

elevations at the time of sampling were determined by 

measuring down from a point on the bridge and related to 

discharge using the rating. The rating-derived discharge 

was used in conjunction with the instantaneous flow data 

at nearby streamflow-gaging stations to estimate 

discharge at the time of sampling. The discharge 

associated with samples taken by the ODEQ was estimated 

by comparison with flow at nearby gages. For samples 

taken on Kelley Creek, discharge data were available only 

at the gage at the mouth of the creek. No flow estimates 

were made for the upstream or tributary sites on Kelley 

Creek. Discharge data for the storm drains were from 

continuous flow meters. These data were provided by the 

Cities of Gresham and Portland.

Precipitation data used in this report were provided 

by the City of Portland Hydra rainfall network (City of 

Portland, Bureau of Environmental Services, 2002a and 

2002b). This network consists of tipping-bucket rain gages 

located throughout the Portland metropolitan area. The 

Holgate rain gage (fig. 1) was selected as a representative
Figure 2. Land cover categories, Johnson Creek Basin, Oregon.
Table 2. Drainage area and land cover for sampling sites, Johnson Creek Basin, Oregon, 1988–2002. 

[Map ID refers to the number on figure 1. Abbreviation: NA, not applicable. Drainage area and land cover data were not available for the storm drains. The urban land cove

sparsely vegetated” in the original data set] 

Land cover, in percent

Map ID Site Name

Johnson 

Creek river 

mile

Drainage 

area 

(square 

miles) Urban Agriculture

Forest (closed 

canopy)

Fores

(scattere

open can

shrub

1 Johnson Creek at Palmblad Road 17.2 12.5 7 50 25 14 2 Johnson Creek at Regner Road (station 

14211400)

15.8 15.4 8 42 30 16 

4 Johnson Creek at SE 190th Avenue 12.6 19.8 11 33 30 21 

10 Johnson Creek at Sycamore (station 14211500) 10.2 26.8 12 31 31 21 11 Johnson Creek at SE 92nd Avenue 5.8 42.6 21 20 25 28 12 Johnson Creek at SE 82nd Avenue 5.5 44.4 21 19 26 28 13 Johnson Creek at SE Stanley Avenue 3.6 46.0 23 18 25 28 14 Johnson Creek at SE 45th Avenue 3.2 47.2 23 18 24 29 15 Johnson Creek at SE 44th Avenue between 

Umatilla Avenue and Tenino St.

3.0 47.3 23 18 24 29 

17 Johnson Creek at Milwaukie (station 14211550) 0.7 53.2 24 16 23 32 18 Johnson Creek at SE 17th Avenue 0.3 53.6 24 16 23 32 19 Johnson Creek at mouth 0.0 53.9 24 16 23 32 

5 Kelley Creek at RM 2.5 NA 0.63 2 11 75 10 6 Kelley Creek at RM 1.2 NA 2.63 5 41 43 9 7 Clatsop Creek at mouth NA 0.34 24 8 32 22 8 Kelley Creek at RM 0.5 NA 4.18 8 37 41 11 9 Kelley Creek at SE 159th Drive (station 

14211499) NA 4.69 9 37 39 11 
8 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002

site in the Johnson Creek Basin. Data from the rain gage 

located at Pleasant Valley School were used in the Kelley 

Creek analysis.

Sample Collection and Analysis

For the USGS sampling in March 2002, unfiltered 

samples for organochlorine-compound analysis were collected as grab samples. Samples were collected directly 

into 1-liter amber glass bottles that had been cleaned and 

then baked at 450°C to remove impurities. For each grab 

sample, the bottle was placed underwater near the center 

of the stream (or storm drain) and filled to the top. Because the waterways were narrow and the flow was turbulent and well-mixed, the typical procedure of obtaining 

depth- and width-integrated samples was not employed. 

Additionally, grab sampling was chosen because it is the 

sampling method used by other agencies (including 

ODEQ) for sampling Johnson Creek. Therefore, the methodologies used for gathering data will be comparable when 

setting TMDLs.

Water samples for TSS were collected in the same 

manner using 1-liter, wide-mouth, plastic bottles. Samples 

for both organochlorine compounds and TSS were maintained at 4°C during shipment to the laboratories.

The USGS National Water Quality Laboratory 

(NWQL) in Lakewood, Colorado, analyzed the samples 

from the March 11–13, 2002, storm for organochlorine 

pesticides and total PCBs using a modification of the 

method described in Wershaw and others (1987). For the 

usual method (NWQL Schedule 1389), samples are 

extracted in hexane and analyzed by gas chromatography/

electron capture detection (GC/ECD). This method was 

modified to enable the added analyses for the o,p’ isomers 

of DDT, DDE, and DDD (instead of only the p,p’ isomers). 

Glassware was triple rinsed with methanol, hexane, and 

acetone to minimize interferences. Information concerning 

the organochlorine compounds analyzed is summarized in 

table 3. 

Several designations were used by the NWQL to 

indicate minimum levels of detection for the particular 

analytical methods. A laboratory reporting level (LRL) 

was used for most of the organochlorine compounds (table 

3). These values reflect the 99% probability (based on data 

collected nationwide in water year 2002) of reporting a 

false negative result. Because detection levels are statistically based, the LRL can change from year to year. A subjective, minimum reporting level (MRL) was used for 

chlordane, toxaphene, and total PCB. The MRL does not 

have the statistical foundation that the LRL has. If a concentration was measured by the laboratory as being less 

than the LRL or the MRL, or if the concentration was too 

small to quantify, the value was reported as a nondetection 

or “less than” value. The laboratory used an “E” remark 

code to identify an estimated concentration. This code was 

used when the identification of a compound was qualitatively confirmed but the concentration was estimated 

because there was greater-than-usual uncertainty about the 

measurement.

The ODEQ laboratory analyzed samples for organochlorine compounds and total PCB in 2001 and 2002. 

Chlorinated pesticides were analyzed using EPA method 

8081, and total PCB was analyzed using EPA method 

8082. These methods use methylene chloride extraction 

followed by an electron capture detection analysis. The 

ODEQ laboratory measured turbidity using a HachTM

2100-AN turbidity meter with formazin as the primary 

standard. The turbidity meter was always used in ratio 

mode, and the light source had a tungsten filament and 

used a filter supplied by Hach.

TSS and turbidity were analyzed by the City of Portland, Bureau of Environmental Services (Peter Abrams, 

written commun., 2002). TSS was analyzed using method 

2450 D, “Total suspended solids dried at 103–105°C” 

(American Public Health Association and others, 1998). 

The water sample was filtered through a glass-fiber filter 

of a known weight, and the residue and filter were dried to 

a constant weight. The weight of the residue from a given 

sample volume represents the concentration of the TSS. 

Turbidity was analyzed using method 2130–B, the nephleometric method, (American Public Health Association, 

1998), which compares the light scattering characteristics 

of the sample with those of a standard. The instrument 

used was a Orbeco-HelligeTM digital direct-reading turbidity meter, Model 965–10A, using white light. The turbidimeter was not operated in the ratio mode and formazin 

standards were used to calibrate the instrument. 

Although both the ODEQ and City of Portland laboratories used formazin standards for turbidity measurements, the HachTM 2100-AN and Orbeco-HelligeTM

turbidity meters may not provide comparable data because 

of the difference in mode of operation (Gray and Glysson, 

2002). No direct data quality comparisons were available 

for the two laboratories.

Quality Assurance

The goal of the quality assurance (QA) segment of 

this study was to quantify the extent to which the laboratory analytical data represent stream conditions and to 

maximize their utility for managing the watershed. To 

achieve this goal, QA checks and measures were made 

both in the field and in the laboratory (table 4). In the field, 

“blank” samples for pesticide analysis were prepared for 

submission to both the USGS laboratory and the ODEQ 

laboratory. The field blanks were prepared by pouring 

certified organic-free water into the sample bottle under 

the sampling conditions (outdoors, near the stream-sampling site), to determine if environmental conditions, 
Study Design and Methods 9

Table 3. Organochlorine compounds analyzed in unfiltered water samples, Johnson Creek Basin, Oregon, 2002, and Oregon 

water quality criteria.

[DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethylene; DDT, dichlorodiphenyltrichloroethane; CAS, Chemical Abstracts 

Service registry number; USGS, U.S. Geological Survey; --, not applicable. LRL, laboratory reporting level, MRL, minimum reporting level; bolded

criteria are those smaller than or equal to the reporting level. The source of the water quality criteria is: Oregon Department of Environmental Quality, 

2003b, “Water Quality Criteria Summary,” table 20, http://www.deq.state.or.us/wq/wqrules/340Div41Tbl20.pdf, accessed 2/11/03]

Analyte CAS 

USGS 

parameter 

code

Reporting 

level type

Reporting level

(μg/L)

Chronic 

freshwater 

criteria 

(μg/L)

Acute 

freshwater 

criteria 

(μg/L)

aldrin 309–00–2 39330 LRL 0.001 -- 3.0

chlordane, technical 57-74-9 39350 MRL .10 0.0043 2.4

o,p’-DDD (o,p’-DDT metabolite)1 53–19–0 -- -- -- -- --

p,p’-DDD (p,p’-DDT metabolite) 72–54–8 39360 LRL .001 -- --

o,p’-DDE (p,p’-DDT metabolite)1 3424–82–6 -- -- -- -- --

p,p’-DDE (o,p’-DDT metabolite) 72–55–9 39365 LRL .001 --

o,p’-DDT1 789–02–6 -- -- -- -- --

p,p’-DDT 50–29–3 39370 LRL .002 -- --

Total DDT2 -- -- -- -- .001 1.1

dieldrin 60–57–1 39380 LRL .001 .0019 2.5

endosulfan I (α-endosulfan, 

Thiodan)

959–98–8 39388 LRL .002 .056 .22

endrin 72–20–8 39390 LRL .002 .0023 .18

 lindane (γ-HCH, gammahexachlorocylohexane, γ-BHC)

58–89–9 39340 LRL .0007 .08 2.0

heptachlor (Velsicol 104) 76–44–8 39410 LRL .002 .0038 .52

heptachlor epoxide (heptachlor 

metabolite)

1024–57–3 39420 LRL .001 -- --

p,p’-methoxychlor (Marlate) 72–43–5 39480 LRL .002 .03 --

mirex (dechlorane) 2385–85–5 39755 LRL .001 .001 --

toxaphene 8001–35–2 39400 MRL 1.0 .0002 .73

total PCB (polychlorinated 

biphenyl)

1336–36-3 39516 MRL .10 .014 2.0

1Analysis for the o,p’ isomers were not standard procedures for the USGS National Water Quality Laboratory, and the results of these analyses 

are not stored in the main NWIS database. These data are on file at the USGS Portland office and are in an alternate NWIS database.

2 “Total DDT” in this context refers to the sum of six analytes: o,p’-DDD, p,p’-DDD, o,p’-DDE, p,p’-DDE, o,p’-DDT, and p,p’-DDT. 

For any given environmental sample, one, several, or all of these compounds may have been analyzed.

sample bottles, or laboratory procedures were introducing 

contamination to the water sample. Two field blanks were 

submitted to the USGS laboratory, one from Johnson 

Creek at Sycamore, and one from the storm drain at 

Gresham City Park. One field blank was submitted to the 

ODEQ laboratory, from the storm drain at Gresham City 

Park. No organochlorine compounds were detected in any 

of the field blanks (table 4), indicating that no measurable 

contamination had occurred.

Several QA activities were performed at Johnson 

Creek at SE 45th Avenue on March 11, corresponding to 

the sample time of 16:00 hours. At this time and place, 

streamflow was on the rising limb of the hydrograph (fig. 

3) and organochlorine-compound concentrations were also 

beginning to increase. One large grab sample was taken 

from the stream in a glass carboy and split into four replicate subsamples (two each for the USGS and ODEQ laboratories). For this procedure, a teflon cone-splitter was 

used, a device specially made to obtain representative subsamples from a single container of water (Capel and Larson, 1996). The purpose of replicate samples was to 

determine the variability in the results due to sample preparation and laboratory analysis, within and among laboratories. 

The concentrations of organochlorine compounds in 

the two replicates for the USGS laboratory were very similar to each other (table 4). In both replicates, only three 

compounds were detected (dieldrin, p,p’-DDE, and p,p’-

DDT), and for each of these compounds, one replicate 

sample differed from the other by less than 0.001 μg/L. 

Two of the replicate samples were also submitted to the 

ODEQ laboratory (table 4), and in addition to the three 
Table 4. Quality control data for the U.S Geological Survey (USGS) and Oregon Department of Environmental Quality (ODEQ) laboratories, 

[DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethylene; DDT, dichlorodiphenyltrichloroethane; PCB, polychlorinated biphenyls; <, not 

Sample type Site number 

Sample date

 and time 

Analyzing 

laboratory

Aldrin

(μg/L)

Chlordane

(μg/L)

p,p’-DDD

(μg/L)L

o,p’-DDD

(μg/L)

p,p’-DDE

(μg/L)

o,p’-DDE

(μg/L)

p,p’-DDT

(μg/L)

o,p’-DDT

(μg/L)

Field blank 14211500 3/11/02 12:38 USGS <0.0011 <0.1000 <0.0015 <0.001 <0.0011 <0.001 <0.0019 <0.001

Field blank 452951122254600 3/11/02 14:18 USGS <.0011 <.1000 <.0015 <.001 <.0011 <.001 <.0019 <.001

3/11/02 14:18 ODEQ <.0010 <.010 <.0010 NA <.0010 NA <.0020 NA

Field replicate 452743122365400 3/11/02 16:20 USGS <.0011 <.1000 <.0015 <.001 .0012 <.001 E .0017 <.001

Field replicate 452743122365400 3/11/02 16:21 USGS <.0011 <.1000 <.0015 <.001 .0015 <.001 .0019 <.001

Field replicate 452743122365400 3/11/02 16:20 ODEQ <.0011 <.011 <.0011 NA .0036 NA .0085 NA

Field replicate 452743122365400 3/11/02 16:21 ODEQ <.0011 <.011 <.0011 NA .0032 NA .0048 NA

Field replicate spike 

with expected concentration = 0.054 μg/L

452743122365400 3/11/02 16:25 USGS .0218 <.1000 .026 .0253 .026 .0212 .0267 .0265

Field replicate spike 

with expected concentration = 0.052 μg/L

452743122365400 3/11/02 16:24 USGS .023 <.1000 .0278 .0262 .0276 .0227 .0285 .028

Field replicate spike 

with expected concen- tration = 0.054 μg/L

452743122365400 3/11/02 16:25 ODEQ .0434 <.011 .1446 NA .0502 NA .0812 NA

Laboratory blank NA USGS <.0011 <.1000 <.0015 <.001 <.0011 <.001 <.0019 <.001

Laboratory blank NA USGS <.0011 <.1000 <.0015 <.001 <.0011 <.001 <.0019 <.001

Laboratory blank NA USGS <.0011 <.1000 <.0015 <.001 <.0011 <.001 <.0019 <.001

Laboratory blank NA USGS <.0011 <.1000 <.0015 <.001 <.0011 <.001 <.0019 <.001

Laboratory blank NA ODEQ <.0010 <.010 .0022 NA <.0010 NA <.0020 NA

Laboratory spike NA USGS 49.5 NS 71.6 68.8 66.9 57.5 72.4 71.2

Laboratory spike NA USGS 45.79 NS 68.6 71.02 66.72 57.42 71.61 70.53

Laboratory spike NA USGS 49.23 NS 63.29 61.9 61.87 52.3 64.82 63.7

Laboratory spike NA USGS 52.82 NS 67.27 69.3 66.4 56.59 70.41 68.6

10 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002
Johnson Creek Basin, March 10–13, 2002.

detected at indicated concentration; μg/L, micrograms per liter; NA, not applicable; nd, not detected; E, estimated; NS, not spiked]

Dieldrin

(μg/L)

Endosulfan 1

(μg/L)

Endrin

(μg/L)

Heptachlor

(μg/L)

Heptachlor

Epoxide

Lindane

(μg/L)

p,p Methoxychlor

(μg/L)

o,p Methoxychlor 

(μg/L)

Mirex

(μg/L)

CisNonachlor

(μg/L)

Oxychlordane 

(μg/L)

Toxaphene 

(μg/L)

Total 

PCB

(μg/L)

Alpha 

HCH-d6

Surrogate 

recovery

(% )

 Isodrin

Surrogate 

recovery 

(% )

Nonachlor

Surrogate 

recovery

(% )

<0.0011 <0.0015 <0.0019 <0.0015 <0.0011 <0.0007 <0.0019 <0.001 <0.0011 <0.001 <0.001 <1.000 <0.1000 72 63 54

<.0011 <.0015 <.0019 <.0015 <.0011 <.0007 <.0019 <.001 <.0011 <.001 <.001 <1.000 <.1000 80 58 53

<.0010 <.0010 <.0010 <.0010 <.0010 <.0010 <.0040 NA NA NA NA <.010 nd NA NA NA

 .0026 <.0015 <.0019 <.0015 <.0011 <.0007 <.0019 <.001 <.0011 <.001 <.001 <1.000 <.1000 74 63 49

 .003 <.0015 <.0019 <.0015 <.0011 <.0007 <.0019 <.001 <.0011 <.001 <.001 <1.000 <.1000 75 66 52

<.0011 .0076 .0057 <.0011 <.0011 <.0011 <.0043 NA NA NA NA <.011 nd NA NA NA

 .0082 .0064 <.0011 <.0011 <.0011 <.0011 <.0042 NA NA NA NA <.011 nd NA NA NA

 .0306 .0227 .0295 .023 .0254 .0267 .0192 .027 .0216 .0298 .0038 <1.000 <.1000 60 101 41

 .0331 .0246 .0315 .024 .0268 .0285 .0208 .0292 .0236 .0323 .0149 <1.000 <.1000 65 110 44

 .0674 .05 .0659 .0334 .0404 .0457 .0891 NA NA NA NA <.011 nd NA NA NA

<.0011 <.0015 <.0019 <.0015 <.0011 <.0007 <.0019 <.001 <.0011 <.001 <.001 <1.000 <.1000 100 59 68

<.0011 <.0015 <.0019 <.0015 <.0011 <.0007 <.0019 <.001 <.0011 <.001 <.001 <1.000 <.1000 96 49 51

<.0011 <.0015 <.0019 <.0015 <.0011 <.0007 <.0019 <.001 <.0011 <.001 <.001 <1.000 <.1000 70 49 47

<.0011 <.0015 <.0019 <.0015 <.0011 <.0007 <.0019 <.001 <.0011 <.001 <.001 <1.000 <.1000 81 63 54

<.0010 <.0010 <.0010 <.0010 <.0010 <.0010 <.0040 NA NA NA NA <.010 nd NA NA NA

75.5 47.8 65.1 56.97 63.5 63.4 61.9 72.4 65.95 85.1 63.4 NS NS 91 119 63

67.63 46.14 60.2 54.97 61.22 60.97 40.25 64.58 59.79 77.53 65.06 NS NS 91 111 53

62.87 40.33 62.75 53.24 54.96 55.74 51.24 62.7 58.52 75.3 42.2 NS NS 75 118 53

70.23 43.69 68.28 57.65 59.51 60.03 56.59 68.3 62.73 83.2 66.9 NS NS 81 123 55

Study Design and Methods 11
12 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002

Figure 3. Stream hydrographs, times of sample collection, and precipitation, Johnson Creek Basin, Oregon, March 11–13, 2002.

compounds detected at the USGS laboratory, there were 

small detections of endosulfan I and endrin. For these 

samples from the same site and time, the ODEQ laboratory 

detected p,p’-DDT at an average of 3.7 times larger and 

p,p’-DDE at an average of 2.5 times larger than the USGS 

laboratory. For the replicate samples analyzed for dieldrin 

at the ODEQ lab, the concentrations were very different: in 

one sample dieldrin was not detected (<0.001μg/L), and 

the dieldrin concentration of the other sample at the same 

time and place was 0.008 μg/L.

Replicate field “spikes” also were prepared for the 

QA sampling at the SE 45th Avenue site on March 11. A 

solution containing a known volume and concentration of 

the analytes was introduced (“spiked”) into a native water 

sample. By calculating the amount of the spiked material 

recovered during analysis, an assessment can be made of 

the influence of the native water’s matrix on laboratory 

analyses. Two spiked samples were submitted to the USGS 

laboratory and one was submitted to the ODEQ laboratory 

for organochlorine-compound analysis, along with the 

stream samples. The laboratory results are shown in table

4. A summary of the spike recoveries for the USGS laboratory shows that about 40% to 60% of the spike compounds 

were recovered (table 5). The spike recoveries of DDX and 

dieldrin, the focus of this report, were in the 50% range. 

The ODEQ laboratory also analyzed one of these spiked 

samples, and the recoveries of organochlorine compounds 

were higher and in some cases more variable than the 

recoveries from the USGS laboratory. The ODEQ laboratory’s recoveries ranged from 62% to 268%. Of special 

interest for this report are the high recoveries for p,p’-

DDD (268%) and for p,p’-DDT (138%). These discrepancies in spike recovery between the USGS and ODEQ laboratories are consistent with the lower concentrations 

measured by the USGS laboratory for the USGS/ODEQ 

replicate sample (described above), and may indicate a low 
Table 5. Summary of spike recoveries, U.S. Geological Survey (USGS) and Oregon

Department of Environmental Quality (ODEQ) laboratories, Johnson Creek Basin, 

March 10–13, 2002. 

[Spike recovery was calculated as percent recovery of added spike material. Expected concentrations, where 

available, are in table 4; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethylene;

DDT, dichlorodiphenyltrichloroethane]

Spike recovery, in percent

Compound

USGS field spikes

(average of 2)

USGS lab spikes

(average of 2) ODEQ field spike ODEQ lab spike

p,p'- DDT 50 70 138 136

p,p'- DDE 49 65 87 97

p,p'- DDD 52 68 268 160

dieldrin 56 69 117 100

aldrin 43 49 80 77

endosulfan 1 45 44 80 84

endrin 59 64 117 94

lindane 53 60 85 80

heptachlor 45 56 62 81

heptachlor epoxide 50 60 75 80

p,p'-methoxychlor 38 52 165 231

o,p'-DDT 52 69

o,p'-DDE 42 56

o,p'-DDD 50 68

mirex 43 62

Study Design and Methods 13

bias in the USGS laboratory and a high bias for the ODEQ 

laboratory. However, analyte concentrations were not 

corrected based on spike recoveries because spike 

recoveries are not rigorously quantitative. Instead, the 

spike recoveries can be used as indications that the 

reported values may be lower or higher than the true 

concentrations. 

In addition to the field QA procedures, there were 

also QA efforts as part of the routine procedures for laboratory analysis. In both the USGS and ODEQ laboratories, 

aliquots of organic-free water (laboratory blanks) were 

analyzed along with the environmental samples. The samples analyzed by the USGS laboratory were in sets containing about 12 samples each. The March 2002 samples 

were analyzed in four sample sets, with one laboratory 

blank and one laboratory spike (described below) per set 

(table 4). As was the case with the USGS field blanks, 

there were no detections of compounds analyzed for in the 

laboratory blanks, indicating that there was no reason to 

expect laboratory contamination. However, p,p’-DDD was 

detected at a concentration of 0.002 μg/L in the ODEQ 

laboratory blank. (The detection level of this constituent 

for the ODEQ laboratory was 0.001 μg/L).

Laboratory spikes also were prepared and analyzed 

at the laboratories. For laboratory spikes, organic-free 

blank water was spiked with known concentrations of the 

analytes. Laboratory spikes were added to blank water 

rather than to native stream water, avoiding interference 

(matrix effects) from sediment particles or other compounds that may exist in the native water. This provides a 

direct test of laboratory bias or contamination. For the 

USGS laboratory, the average recovery of each constituent 

(with one exception, endosulfan I) of the four laboratory 

spikes was larger than the average of the two field spikes. 

For the DDT compounds and dieldrin, the USGS laboratory spikes were recovered, on the average, at about 70 

percent.

For the ODEQ laboratory, the recoveries of the constituents in the laboratory spike were sometimes larger and 

sometimes smaller than the corresponding constituent in 

the field spike (table 5). For DDX and dieldrin, the recovery in the laboratory spike was closer to 100% (the optimal 

recovery) than the field spike. Based on those two samples, 

it may be possible to hypothesize that matrix effects in the 

field spike biased the ODEQ laboratory away from 100% 

recovery.

At the USGS laboratory, three surrogate compounds 

were mixed with each native sample before analysis. Surrogate compounds have a similar chemical structure to the 

analytes, but are not expected to be found in the environment. Surrogate recoveries indicate the general efficiency 

of the laboratory analysis for the particular analytical 

group. The concentration of these surrogates, when compared to the expected concentration, was used to calculate 

the percent recovery of each surrogate compound. The surrogate compounds were isodrin (parameter code 90571, 
14 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002

CAS number 465–73–6), alpha-HCH–d6 (parameter code 

99777), and PCB 207 (parameter code 99780 and CAS 

number 52663–79–3). The median recoveries were about 

60 percent, about 70 percent, and about 50 percent, respectively (fig. 4). These recoveries were within the same 

approximate range as the USGS field spikes and laboratory 

spikes (table 5). The recovery of the alpha-HCH-d6 surrogate most closely reflects the method’s performance for 

the constituents of interest in this report—DDT and its 

metabolites and dieldrin (Duane Wydoski, USGS National 

Water Quality Laboratory, written commun., 2003). For 

each surrogate compound, the sample with the smallest 

recovery (shown as the lower point on for each compound 

on fig. 4) was from the same sample—Johnson Creek at 

Palmblad on March 11, 2002, at 15:00 hours, indicating a 

consistently low recovery of compounds in this sample.

Figure 4. Surrogate recoveries by the USGS laboratory, samples of 

Johnson Creek Basin, Oregon, March 2002.

To summarize the quality-assurance efforts, the field 

and laboratory blanks indicated no contamination, with the 

exception of the detection of p,p’-DDD at a low concentration in the ODEQ laboratory blank. Field spikes, replicates, laboratory spikes, and USGS surrogates all indicated 

that the USGS laboratory may be biased toward reporting 

lower-than-real values for organochlorine compounds and 

that the ODEQ laboratory may be biased toward reporting 

higher-than-real values for these compounds.

Results

Water-quality results presented here include several 

elements. The hydrologic conditions of March 11–13, 

2002, are described to provide context for the samples 

taken during that storm event. Next, the occurrence of 

organochlorine compounds during the March 2002 storm, 

as well as in samples taken by ODEQ during nonstorm 

periods, is discussed. Results are compared to water-quality standards. Instantaneous loads were computed to assess 

the flux of pesticides in the basin. The relation of sediment 

parameters (TSS and turbidity) is explored; this relation 

provides a means of comparing current sediment-pesticide 

associations with sediment and pesticide data collected a 

decade ago. Finally, samples taken from Kelley Creek, a 

tributary to Johnson Creek, in 2002 and 2003 provided an 

indication of both spatial and temporal differences in pesticide concentrations. 

Hydrologic Conditions during Storm Sampling

The storm of March 11 and 12, 2002 (fig. 5), was a 

typical winter storm, with a peak flow at the Milwaukie 

gage of about 650 cubic feet per second (ft3/s). The peak 

discharge at the Milwaukie gage on March 11 had been 

exceeded four times since October 2001. The peak at the 

Sycamore gage was 524 ft3/s, corresponding to a recurrence interval of less than 1 year (Wellman and others, 

1993). The goal was to sample on the rising and falling 

limbs of the hydrograph, and also to sample near the peak 

discharge. Since organochlorine compounds are associated 

with suspended sediment, which is usually transported to 

the greatest degree near the storm peak, sampling throughout the hydrograph would best describe the instantaneous 

loading and transport of organochlorine compounds during 

a given storm event.

Figure 3 depicts the storm hydrographs for Johnson 

Creek, precipitation during the storm, and times of sample 

collection. Discharge from the gaging station at Gresham 

(RM 15.8) is shown along with the estimated discharge at 

Palmblad Road (RM 17.2) at the time of each of the six 

samples. Precipitation data are also shown for the Holgate 

rain gage (City of Portland, Bureau of Environmental Services, 2002a). The most intense precipitation preceded the
Results 15

Figure 5. Stream hydrograph of Johnson Creek at Milwaukie, Oregon, October 2001 through March 2002.

storm peak by several hours. The six samples at Palmblad 

Road were well distributed over the stream hydrograph.

The storm hydrograph and discharge associated with 

each sample time for Johnson Creek at Sycamore are also 

shown in figure 3. Because the samples were collected at 

the stream-gaging station, the discharge at the time of sampling corresponds exactly to the storm hydrograph line. 

The hydrograph at the Sycamore gage was similar in shape 

to that at the Gresham gage, but the peak discharge at 

Sycamore was larger, of longer duration, and occurred 

slightly later than at Gresham. A small secondary peak at 

Sycamore in the morning of March 12 corresponds to a 

subsequent rainfall event. Five of the six samples at the 

Sycamore gage were taken on the rising limb of the 

hydrograph. A sample was taken near the peak discharge.

Three of the four samples at the SE 45th Avenue site 

were taken on the rising limb of the hydrograph (fig. 3). 

The discharge at the time of sampling prior to the peak and 

after the peak was approximately half the peak discharge.

The peak at Johnson Creek at Milwaukie was larger 

and occurred later than the upstream sites (fig. 3). The 

peak discharge occurred shortly after midnight and no 

samples were taken near the peak of the hydrograph. As 

with the samples taken at the SE 45th Avenue site, the discharge at the time of sampling prior to the peak and following the peak was about half the peak discharge.

The flow hydrographs of the two storm drains 

located at Gresham City Park and at SE 45th Avenue and 

Umatilla Street indicate a typical urban-runoff response 

(fig. 6). The catchment for both sites consists of rooftops, 

streets, and landscaped areas. The Gresham site drains part 

of the downtown core of the city of Gresham, whereas the 

45th Avenue site primarily receives water from a mix of 

residential and industrial areas. In contrast to the stream 

sites, in which several hours of precipitation led to a rapid 

rise with a distinct single peak followed by a gradual 

recession, runoff in the storm drains rose and fell rapidly 

in response to precipitation. 

The flow responses of the two storm drains to the 

precipitation event of March 11 were fairly similar (fig. 6). 

The data-recording interval at the Gresham site was 2 

hours, whereas the recording interval at the SE 45th Avenue site was 15 minutes, so the Gresham hydrograph has 

fewer data points. Some differences in the hydrology of 

the two catchments are evident from the respective hydrographs. The base flow of the Gresham storm drain is minimal, but the base flow at the SE 45th Avenue site is about 

1 ft3/s. The base-flow component at the SE 45th Avenue 

site is due to interception of spring discharge in the area. 

Errol Spring, located 0.2 miles east of the SE 45th Avenue 

sampling site, does not flow into the storm drain, but it is 

indicative of springs that emanate from the hillside north 
16 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002

Figure 6. Discharge at storm drains, times of sample collection, and precipitation, Johnson Creek Basin, Oregon, March 11, 2002.

of the storm drain. The occurrence of spring flow in this 

storm drain is substantiated by flow measurements made in 

1988, 1999, and 2000 (U.S.Geological Survey, 1989, 2000, 

2001). Based on the peak discharge at both storm drains 

early on March 11 of about 5 ft3/s, followed by a peak of 

about 10 ft3/s at each site, the catchment of both sites may 

be of similar size, although the dimension of each 

catchment was not determined. The effect of ground-water 

discharge at the 45th Avenue site, which amounts to about 

10 percent of the peak discharge, was not explored, but 

factors such as the contributing area to the springs and age 

of these waters may have an effect on the data.

The samples taken from both storm drains were 

fairly well distributed on the flow hydrograph (fig. 6). 

Based on both the precipitation and flow data, samples 

were taken near the peak discharge at each site.

Occurrence of Organochlorine Pesticides and 

Compliance with Criteria

The analysis of whole-water samples from the storm 

of March 11–13, 2002 (table 6), was the primary source of 

data for both this section and the following section concerning loads. In addition to organochlorine pesticides, 

analyses were done for total PCB, turbidity, and TSS. Also 

discussed in these sections are organochlorine-pesticide 

data from ODEQ sampling and analysis from December 

2001 and January 2002 (table 7). The ODEQ data set 

includes 11 samples from 5 sites on Johnson Creek, data 

that are useful for helping to assess the occurrence of organochlorine pesticides in the basin, particularly during nonstorm periods.

The USGS laboratory, under a special agreement, 

quantified the o,p’ isomers (as well as the more standard 

p,p’ isomers) of DDT, DDE and DDD (table 6), whereas 

the ODEQ laboratory quantified only the p,p’ isomers of 

DDT, DDE and DDD (table 7). Of the 32 samples analyzed 

by the USGS, 22 contained at least 1 of the DDX compounds, and only 4 contained 1 of the o,p’ DDX compounds (table 6). The concentration of o,p’ isomers of 

three of these four samples was less than 6% of the total 

concentration, and the o,p’ component of the other sample 

was 20% of the total DDT. Due to the small component of 

the o,p’ isomers, the data from the USGS laboratory 

(where the full analysis was done) were treated the same as 

the data from the ODEQ laboratory (where the analysis 

was limited to the p,p’ isomers). In this report, the term 

“total DDT” refers to the sum of all DDT + metabolite 

concentrations, including all analyzed isomers.

Organochlorine pesticides were detected from the 

March 2002 sampling at five of the six sites (table 6). 

There were no detections of any of the analytes in samples 
Results 17

from the storm drain in Gresham City Park. DDX compounds were detected at every other site. There were single 

detections of the following compounds: chlordane and 

endosulfan I at Palmblad Road, p,p’-methoxychlor at Milwaukie, and total PCB at the storm drain at SE 45th and 

Umatilla Street. The highest concentration of total DDT 

was 0.07 μg/L at the Palmblad site on March 11 at 20:40 

hours, during the peak of the storm. Dieldrin was detected 

in every stream water sample, but not in any of the samples 

from the storm drains. The sample with the highest total 

DDT concentration also had the highest concentration of 

dieldrin (0.02 μg/L) and the only detection of chlordane 

(an estimated value of 0.1 μg/L). The relatively high concentrations of both total DDT and dieldrin at the Palmblad 

Road site may reflect the historical agricultural land use in 

the upper watershed. This is consistent with findings at 

Kelley Creek, described later in the report, showing high 

organochlorine compound concentrations in the part of the 

stream draining areas that are now predominately agricultural and may have also been agricultural in the past. 

For the ODEQ samples of December 5 and 19, 2001, 

and January 9, 2002, organochlorine compounds were 

detected in every sample (table 7). Both DDX compounds 

and dieldrin were detected in every sample. Endosulfan I 

was detected at every site, and overall there were one or 

more detections of aldrin, endrin, and heptachlor. The 

highest concentration of total DDT was 0.008 μg/L at the 

SE 190th Avenue site on December 5, 2001. The highest 

dieldrin concentration was 0.008 μg/L at the Palmblad 

Road site, also on December 5, 2001.

Although both dieldrin and DDX compounds were 

detected in numerous samples by the USGS and ODEQ, 

the concentrations of these compounds were not well correlated, especially at the lower concentrations (fig. 7). For 

the March 2002 storm-event sampling, several stream samples had detections of dieldrin but not DDX. Only samples 

from the storm drain at SE 45th Avenue indicated the 

occurrence of DDX and not dieldrin. The dieldrin concentration of most of the March 2002 samples was between 

30% and 100% of the total DDT concentration (table 6). 

Samples taken by the ODEQ on December 5, 2001, and 

January 9, 2002, contained fairly similar concentrations of 

dieldrin and total DDT; however, samples taken on December 19, 2001, had dieldrin concentrations generally more 

than twice that of total DDT (table 7).

Two previous studies indicated generally lower concentrations of dieldrin relative to total DDT. Dieldrin concentrations, relative to total DDT, were smaller for 

samples taken during storms in 1989–90 (Edwards, 1994). 

Analyses using semipermeable membrane devices in 1997 

and 1998 (McCarthy and Gale, 1999) found that the dieldrin concentration in Johnson Creek at Milwaukie was 

one-third to two-thirds that of total DDT.

The lack of correlation of dieldrin to total DDT may 

be attributable to the chemical characteristics of these 

compounds. Dieldrin is more soluble in water than DDT 

(Smith and others, 1988, p. 29). Although the source of 

both dieldrin and DDX in the stream may be soil erosion, 

resulting in introduction of contaminated sediments to the 

stream, more dieldrin may be in the dissolved state relative 

to DDX. This could result in persistence of dieldrin in the 

stream even during nonstorm periods. The highly variable 

relation of dieldrin to total DDT may be dependent on sediment concentration and the time of exposure of contaminated sediments in the stream, differences in degradation 

of these compounds, and (or) geographical differences in 

their application. 

Overall, the concentrations of both total DDT and 

dieldrin were lower in the 2001–02 samples than in the 

1989–90 samples. Differences in storm magnitude and 

antecedent conditions may cloud the comparison of organochlorine-compound concentrations in 1989–90 to those 

of 2001–02. The December 1989 storm was of slightly 

greater magnitude; the recurrence interval was 1.25 years 

(Wellman and others, 1993) compared to a recurrence 

interval of less than 1 year for the March 2002 storm. The 

storm of January 1990 was slightly smaller than the March 

2002 storm. Despite the small difference in peak discharges, the difference in organochlorine-pesticide concentrations was substantial. The total DDT concentration 

of every sample taken in 1989–1990 (shown in table 8) 

was equal to or greater than 0.05 μg/L, but only one sample in 2001–02 had a higher concentration (table 6). For 

dieldrin, the concentration of every sample from 1989–90 

was greater than 0.01 μg/L, but the 2001–02 data indicate 

that only 2 of 34 samples contained concentrations above 

0.01 μg/L. For both DDT and dieldrin, the decrease may be 

due to degradation, deposition, or transport out of the 

basin. 

The data suggest that decreases in total DDT (which 

includes the parent compound DDT plus the degradation 

products DDD and DDE) from 1989 to 2002 may possibly 

have been due more to transport of these compounds out of 

the basin than to degradation. In natural systems, DDT is 

biotransformed into DDD and DDE (Smith and others, 

1988, p. 31). For both the recent samples and those taken 

more than 10 years before, the concentration of the parent 

compound DDT is one-half to two-thirds of the total DDT 

concentration (tables 6 and 8). Therefore, degradation has 

not taken place to a great extent, and transport may be the 

dominant process. 

The State of Oregon promulgated water-quality criteria for 11 of the 18 compounds that were analyzed by the 

USGS (table 3). The Oregon criteria were based on guidelines established by the U.S. Environmental Protection 

Agency (1986). The criteria considered in this report were 

the chronic criteria for the protection of freshwater aquatic 

life. The chronic freshwater standard was based on a 96-

hour (4-day) average concentration. In this study, there 

were insufficient data to determine the average over a 96-

hour period, so it was considered that a criterion was 

potentially exceeded if the numerical value was exceeded 
Table 6. Organochlorine-compound and streamflow data, Johnson Creek Basin, Oregon, March 11–13, 2002.

[USGS, U.S. Geological Survey; ft3/s, cubic feet per second; NTU, nephelometric turbidity units; mg/L, milligrams per liter; μg/L, micrograms per liter; <, not 

dichloroethylene; DDT, dichlorodiphenyltrichloroethane; E, estimated]

Map ID Site name USGS site number Date Time

Discharge

(ft3

/s)

Turbidity

(NTU)

Total 

suspended 

solids

(mg/L)

 Aldrin

(μg/L)

Chlordane

(μg/L)

p,p' - DDD

(μg/L) 

o,p' DDD

(μg/L)

1 Johnson Creek at Palmblad Road 452823122240900 20020311 1220 70 85 64 <0.001 <0.1 <0.002 < 0.001

20020311 1500 110 260 186 <.001 <.1 <.002 <.001

20020311 1650 110 300 202 <.001 <.1 <.002 <.001

20020311 2040 440 800 1190 <.001 *E0.1 *.002 <.001

20020312 810 125 80 48 <.001 <.1 <.002 <.001

20020312 1550 125 65 41 <.001 <.1 <.002 <.001

10 Johnson Creek at Sycamore 14211500 20020311 1020 75 21 10 <.001 <.1 <.002 <.001

20020311 1230 156 55 57 <.001 <.1 <.002 <.001

20020311 1550 190 55 33 <.001 <.1 <.002 <.001

20020311 1820 380 230 266 <.001 <.1 <.002 <.001

20020311 2120 500 300 321 <.001 <.1 *E.001 <.001

20020312 900 266 110 84 <.001 <.1 <.002 <.001

14 Johnson Creek at SE 45th Avenue at 452743122365400 20020311 1130 145 38 30 <.001 <.1 <.002 <.001

Portland. Discharge estimated— 

continuous data not available 20020311 1620 255 65 84 <.001 <.1 <.002 <.001

20020311 1910 320 120 125 <.001 <.1 <.002 <.001

20020312 940 320 200 123 <.001 <.1 <.002 <.001

17 Johnson Creek at Milwaukie 14211550 20020311 1120 131 27 22 <.001 <.1 <.002 <.001

20020311 1341 144 45 28 <.001 <.1 <.002 <.001

20020311 1630 276 70 80 <.001 <.1 <.002 <.001

20020311 1940 345 90 106 <.001 <.1 <.002 <.001

20020312 1020 354 200 123 <.001 <.1 <.002 <.001

20020313 1040 221 50 26 <.001 <.1 <.002 <.001

3 Storm Drain at Gresham City Park 452951122254600 20020311 1140 3 26 23 <.001 <.1 <.002 <.001

20020311 1410 1 34 18 <.001 <.1 <.002 <.001

20020311 1610 5 50 63 <.001 <.1 <.002 <.001

20020311 1730 8 60 86 <.001 <.1 <.002 <.001

16 Storm Drain at SE 45th Avenue and 

Umatilla Street

452750122365300 20020311 1050 4 60 49 <.001 <.1 <.002 <.001

20020311 1220 5 75 77 <.001 <.1 <.002 <.001

20020311 1400 3 39 31 <.001 <.1 <.002 <.001

20020311 1500 2 28 18 <.001 <.1 <.002 <.001

20020311 1530 10 160 301 <.001 <.1 <.002 <.001

20020311 1730 6 85 86 <.001 <.1 <.002 <.001

18 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002
detected at indicated level; * indicates detections of organochlorine compounds; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenylp,p'-DDE

(μg/L)

o,p'-DDE

(μg/L)

p,p'-DDT

(μg/L)

o,p'-DDT

(μg/L)

Dieldrin

(μg/L)

Endosulfan I

(μg/L)

Endrin

(μg/L)

Lindane

(μg/L)

Heptachlor

(μg/L)

Heptachlorepoxide

(μg/L)

p,p'-methoxychlor

(μg/L)

 Mirex

(μg/L)

Toxaphene

(μg/L)

Total 

PCB

(μg/L)

*0.004 <0.001 *0.006 < 0.001 *0.003 <0.002 <0.002 <0.0007 <0.002 <0.001 <0.002 <0.001 <1 <0.1

*.006 <.001 *.009 <.001 *.005 *E.001 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.011 *.001 *.021 <.001 *.016 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.029 *.003 *.036 *.001 *.021 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.003 <.001 .003 <.001 *.007 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.002 <.001 *.003 <.001 *.005 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

<.001 < .001 <.002 <.001 *.003 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.002 <.001 *.002 <.001 *.005 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.002 <.001 *E.002 <.001 *.004 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.006 <.001 *.006 *.003 *.005 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.006 <.001 *.009 *E.001 *.007 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.004 <.001 *.005 <.001 *.006 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

<.001 <.001 <.002 <.001 *.002 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.001 <.001 *E.002 <.001 *.003 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.002 <.001 *E.002 <.001 *.003 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.005 <.001 *.008 <.001 *.008 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

<.001 <.001 <.002 <.001 *.002 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

<.001 <.001 <.002 <.001 *.002 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.001 <.001 *.004 <.001 *.003 <.002 <.002 <.0007 <.002 <.001 *.004 <.001 <1 <.1

*.002 <.001 *.002 <.001 *.003 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.005 <.001 *.007 <.001 *.006 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*.002 <.001 *.003 <.001 *.005 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

<.001 <.001 <.002 <.001 <.001 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

<.001 <.001 <.002 <.001 <.001 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

<.001 <.001 <.002 <.001 <.001 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

<.001 <.001 <.002 <.001 <.001 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

<.001 <.001 <.002 <.001 <.001 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

<.001 <.001 *.003 <.001 <.001 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

<.001 <.001 *E.002 <.001 <.001 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

<.001 <.001 <.002 <.001 <.001 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

*E.001 <.001 *.017 <.001 <.001 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 <.1

<.001 <.001 *E.001 <.001 <.001 <.002 <.002 <.0007 <.002 <.001 <.002 <.001 <1 *E.1

Results 19
Table 7. Organochlorine-compound and streamflow data collected and analyzed by Oregon Department of Environmental Quality, Johnson Creek, O

[<, not detected at indicated concentration; NA, not available; NTU nephelometric turbidity units; ft3/s, cubic feet per second; mg/L, milligrams per liter; μg/L micrograms per lidichloroethane; DDE, dichlorodiphenyldichloroethylene; DDT, dichlorodiphenyltrichloroethane; * indicates detections of organochlorine compounds]

Map ID Site name

Sample date 

and time

Estimated discharge

(ft3/s) Turbidity (NTU)

Total 

suspended 

solids

(mg/L)

Aldrin

(μg/L)

p,p'-DDD

μg/L)

p,p'-DDE

(μg/L)

p,p'-DDT

(μg/L)

Dieldrin

(μg/L)

Endosulfan

(μg/L) 1

1 Johnson Creek at Palmblad Road 12/5/01 12:00 180 58 40 NA <0.0010 *0.0034 *0.0031 *0.0077 *0.0043 1 Johnson Creek at Palmblad Road 12/19/01 12:25 80 27 10 <0.0010 <.0010 *.003 <.0010 *.007 *.004 4 Johnson Creek at SE 190th Avenue 12/5/01 11:25 260 84 87 NA NA *.0047 *.0036 *.0066 *.0048 4 Johnson Creek at SE 190th Avenue 12/19/01 11:50 100 31 19 NA NA *.0014 NA *.0051 *.0028 4 Johnson Creek at SE 190th Avenue 1/9/02 12:10 100 26 15 <.0010 *.002 *.0022 *.0028 *.006 *.0024 

11 Johnson Creek at SE 92nd Avenue 12/19/01 11:10 150 42 16 NA NA *.0012 NA *.0043 NA 11 Johnson Creek at SE 92nd Avenue 1/9/02 11:40 160 37 21 <.0011 *.0012 *.0024 <.0020 *.0052 *.0022 14 Johnson Creek at SE 45th Avenue 12/19/01 10:40 160 42 20 NA NA *.0019 *.0025 *.0064 NA 14 Johnson Creek at SE 45th Avenue 1/9/02 11:15 160 32 20 *.0013 *.0025 NA *.0024 *.0054 *.0022 18 Johnson Creek at SE 17th Avenue 12/19/01 10:00 180 50 20 NA NA *.0024 *.0028 *.0053 NA 18 Johnson Creek at SE 17th Avenue 1/9/02 10:40 180 34 22 <.0010 *.0013 *.0015 *.002 *.0053 *.0022 
Results 21

Figure 7. The relation between the concentrations of total DDT and 

dieldrin, Johnson Creek Basin, Oregon, 2001–02.

even once. However, because the samples covered the 

course of a short-duration storm (1–3 days), with the 

organochlorine-compound concentrations rising and 

falling with stream discharge, it is likely that the 96-houraverage organochlorine-compound concentrations were 

less than the average of the concentrations sampled, and 

therefore that the criteria were not exceeded. Of the 11 

compounds for which criteria have been established, 5 

(chlordane, total DDT, mirex, toxaphene, and PCBs) had 

criteria less than or equal to the reporting level. Any 

detection of these compounds was considered to be an 

potential exceedance of the chronic freshwater criterion. 

In 2001 and 2002, chronic freshwater criteria were 

potentially exceeded for chlordane, total DDT, dieldrin, 

and total PCB (fig. 8). The total DDT and dieldrin standard 

was potentially exceeded at most of the sites and times. 

These results illustrate the ubiquity and long life of DDX 

and dieldrin in the environment. According to the U.S. 

Environmental Protection Agency (1986), they also indicate long-term effects of the organochlorine compounds on 

aquatic organisms, including fish and benthic invertebrates. 

As noted in table 3, the chronic freshwater criterion 

promulgated by the State of Oregon for dieldrin is 0.0019 

μg/L. Recently, the U.S. Environmental Protection Agency 

(2002), has changed their recommended value for this criterion to 0.056 μg/L. If the State of Oregon follows this 

recommendation and changes their criterion for dieldrin, 

none of the samples from the March 2002 storm would 

have had concentrations that exceeded the criterion.

The occurrences of chlordane and PCBs may be the 

result of agricultural uses and urban settings in the basin, 

respectively. Because there was only one detection of each 

compound in the March 2002 sample, the association of 

pesticide occurrence with land cover is not conclusive. The 

only potential exceedance for chlordane was at the Palmblad Road site, which may be related to the fact that much 

of the agriculture in the Johnson Creek Basin is upstream 

of this site. Fifty percent of the land cover in the area 

upstream from this site is agricultural (table 2). Past uses 

for chlordane include insect control on fruit and vegetable 

crops, as well as termite control in urban areas. The only 

potential exceedance for total PCB was in the storm drain 

at SE 45th Avenue, which may be due to the urban land 

uses upstream of this sampling site. 

Loads of Organochlorine Pesticides

The discussion of organochlorine pesticides to this 

point has focused on concentrations, which is appropriate 

for evaluating the occurrence of organochlorine pesticides 

and the comparisons to guidelines or criteria. However, for 

understanding the flux of organochlorine pesticides in the 

Johnson Creek Basin, and assessing possible sources and 

sinks, the load of the organochlorine pesticides must be 

considered. Load is calculated as organochlorine-pesticide 

concentration multiplied by stream discharge. Stream-discharge data were not available for all organochlorine-pesticide samples, and only when both quantities were 

measured was a load calculated.

Figures 9 and 10 show the total DDT and dieldrin 

loads, respectively, and the discharge hydrographs for the 

streamflow-gaging site nearest each sampling site. Loads 

are represented as bars on each graph, and as such are 

instantaneous observations. The load of the entire storm 

was not calculated due to incomplete organochlorine-pesticide data over the storm hydrograph. The discharges used 

for load calculation at the Palmblad Road and SE 45th 

Avenue sites were estimated as described above in the 

hydrologic data section. It should be noted that there are 

two y-axes on figures 9 and 10. The right y-axis of each 

graph is discharge, and the same scale is used for each 

graph. The left y-axis of each graph represents load.

Several factors contribute to uncertainty when comparing organochlorine-pesticide loads over the storm event 

of March 11–13, 2002. First, samples were taken at a small 

number of points (a maximum of six) over the discharge 

hydrograph at each site. Second, comparison of loads to 

the discharge hydrograph does not imply that the peak load 

is simultaneous with the peak stream discharge. Third, the 

source (contributing area) of streamflow at a given time on 

the hydrograph changes, resulting in changes in the proportions of contributing-area land uses. For example, samples taken at the SE 45th Avenue and Milwaukie sites in 

the afternoon of March 11, while on a rapid rise in discharge, likely represented flow derived primarily from 

nearby urban areas and to a lesser extent from the upper 

basin, whereas subsequent flow might have a higher 
Table 8. Organochlorine-compound, streamflow and turbidity data, Johnson Creek Basin, Oregon, 1989–90.

[Data are from Edwards, 1992. Discharge and turbidity data for the sample times shown were estimated from measurements that were taken at slightly different 

times. ft3/s, cubic feet per second; NTU, nephelometric turbidity units; μg/L, micrograms per liter; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethylene; DDT, dichlorodiphenyltrichloroethane]

Site number and name Date Time

Discharge 

(ft3

/s)

Turbidity

(NTU)

p,p’-

DDD 

(μg/L)

p,p’-

DDE

(μg/L)

p,p’-

DDT

(μg/L)

Dieldrin

(μg/L)

452910122251500, Johnson Creek at Regner Road 12–04–89 17:30 450 600 0.070 0.160 0.630 0.060

12–04–89 21:00 600 530 .020 .060 .150 .030

12–04–89 23:50 460 290 .010 .020 .040 .020

01–25–90 16:50 103 155 .033 .042 .180 .020

01–25–90 21:45 103 400 .020 .034 .085 .035

01–26–90 01:15 103 160 .013 .019 .042 .029

14211499, Kelley Creek at 159th Drive 12–04–89 20:30 260 260 .010 .050 .080 .050

01–25–90 21:05 85 190 .011 .029 .044 .028

14211500, Johnson Creek at Sycamore 12–04–89 18:00 600 560 .010 .010 .100 .010

12–04–89 21:25 830 320 .050 .060 .170 .040

12–05–89 00:00 825 390 .010 .030 .080 .030

01–25–90 18:15 250 220 .011 .026 .045 .020

01–25–90 22:30 457 205 .017 .028 .066 .018

45271712234400, Johnson Creek at SE 82nd Avenue 12–04–89 22:15 750 360 .010 .020 .040 .020

01–25–90 22:10 360 190 .011 .020 .042 .017

452722122361100, Johnson Creek at Stanley Avenue 12–05–89 00:00 750 420 .010 .040 .100 .030

01–25–90 22:15 400 270 .012 .020 .040 .016

452750122370000, Johnson Creek at SE 44th Avenue 01–25–90 23:15 400 200 .090 .010 .060 .010

14211550, Johnson Creek at Milwaukie 12–04–89 20:15 600 520 .010 .030 .070 .020

12–05–89 01:30 826 420 .010 .040 .110 .030

01–25–90 21:00 345 190 .010 .013 .025 .012

01–26–90 01:55 530 200 .015 .018 .048 .015

01–26–90 08:15 315 145 .011 .011 .028 .013

22 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002

proportion of contributions from predominantly agricultural areas upstream. Even at the Sycamore site, the 

samples taken on the rising limb of the hydrograph may 

represent a greater proportion of flow from nearby areas 

than the upper watershed. The loads calculated from 

samples taken in the morning of March 12, following the 

peak, indicated that, although the peak load had passed the 

Palmblad Road site and returned to a background level, the 

load at the downstream sites was still elevated.

Total DDT

Total DDT loads for the March 2002 storm were calculated for four sampling sites (fig. 9). The maximum 

instantaneous load of total DDT at the Palmblad Road site 

was 76 grams per day, coinciding with the timing of the 

peak discharge. Before and after the peak of total DDT and 

discharge, there was a small, but measurable load of total 

DDT at each sampling time, which may represent a background level of total DDT at the Palmblad Road site. 

The peak total DDT load attenuated between the 

Palmblad Road site (fig. 9A) and the Sycamore site (fig. 

9B) downstream, while peak stream discharge increased. 

The large total DDT load at the Palmblad Road site indicates a source in the upper Johnson Creek Basin, the land 

use within which is largely agricultural (fig. 2 and table 2). 

Although no sample was taken at the peak discharge of 

524 ft3/s at the Sycamore site, a sample was taken 2 hours 

prior to the peak at a discharge of 496 ft3/s. The load of 
Results 23

Figure 8. Potential exceedances of Oregon water quality criteria, 

Johnson Creek Basin, Oregon, 2001–02.

this sample was 21 grams per day. The samples taken at 

the Palmblad Road and Sycamore sites in the morning of 

March 12 indicate the total DDT load may attenuate fairly 

rapidly at the upper site. About 10 hours after the peak 

discharge at the Sycamore gage, the load of total DDT was 

about 5 grams per day, or about one-quarter of the peak 

load. Again, due to the small number of samples, it was 

not possible to calculate a total-storm load for each site. 

No samples were taken at the SE 45th Avenue or 

Milwaukie sites (fig. 9C) during the peak streamflow 

(which probably coincided approximately with the maximum total DDT concentration), so calculation of the peak 

total DDT load downstream of the Sycamore gage could 

not be determined. The highest load measured was 10 

hours after the peak and was about 10 grams per day. The 

similarity in loads at the SE 45th Avenue and Milwaukie 

sites, based on samples taken at nearly the same time, indicates that there was little input of total DDT between the 

two sites. Although DDX was detected in the storm drain 

at SE 45th Avenue (located between the stream-sampling 

location at SE 45th Avenue and the Milwaukie gage), the 

discharge from the drain was less than 3 percent of the 

stream discharge, adding little in terms of load to the 

stream.

Dieldrin

Dieldrin was detected in every stream (non-stormdrain) sample in the March 2002 storm (fig. 10). As was 

the case for total DDT, the highest instantaneous load of 

dieldrin, 23 grams per day, occurred at the Palmblad Road 

site near the peak in discharge (fig. 10A). Again, this suggests a historical agricultural source of dieldrin in the 

Johnson Creek Basin. The peak load at Sycamore was 

about 8 grams per day (fig. 10B), smaller than that at 

Palmblad Road. The largest measured loads at SE 45th 

Avenue and at Milwaukie were about 6 and 5 grams per 

day, respectively (fig. 10C). However, as noted above, no 

samples were taken near the peak streamflow at either site, 

so the peak load of dieldrin at the SE 45th Avenue and 

Milwaukie sites probably was not documented.

Relation of Total Suspended Solids to Turbidity

To compare recent water-quality results (including 

comparisons of organochlorine-pesticide concentrations to 

a sediment parameter) with previous studies, it was necessary to determine the relationship between TSS and turbidity (fig. 11). The 1989–90 study (Edwards, 1992) 

included only turbidity measurements, and the sampling of 

2001 and 2002 included both turbidity and TSS data. 

An analysis was made of all samples for which both 

TSS and turbidity were measured. This data set comprised 

78 samples, including samples collected from Johnson 

Creek and storm drains March 11–13, 2002 by the USGS 

and analyzed by the City of Portland Bureau Environmental Services (BES) laboratory (table 6); samples taken and 

analyzed by the ODEQ on Johnson Creek in 2001–02 

(table 7); and samples collected by the City of Portland 

from Kelley Creek in 2002–03 (table 9). There may have 

been a bias resulting from the use of different turbidity 

instruments by the ODEQ and BES laboratories, but the 

magnitude and direction of any such bias is unknown.

A linear regression was done on the turbidity values 

to estimate TSS. Of the 78 values, one high value (a peak 

value at Johnson Creek at Palmblad Road, March 11, 2002 

at 20:40) was not used. If used, this high value would have 

had undue influence on the regression and would have 

skewed the relation of TSS to turbidity, particularly at low 

TSS concentrations. For the purposes of this study, the 

relation at low TSS concentrations was of primary importance. Of the 77 remaining samples, the relation was determined to be TSS (in mg/L [milligrams per liter]) = 0.88 x 

turbidity (in nephleometric turbidity units). The regression 

line was forced through the origin, and had an r2 of 0.82. A 

plot of the residuals indicated the residuals were fairly 

well balanced about zero. This equation was applied to the 
24 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002

Figure 9. Total DDT loads and streamflow hydrographs, Johnson Creek Basin, Oregon, March 11–13, 2002. A, upper basin site; B, middle basin site; 

C, lower basin sites.
Results 25

Figure 10. Dieldrin loads and streamflow hydrographs, Johnson Creek Basin, Oregon, March 11–13, 2002. A, upper basin site; B, middle basin site; 

C, lower basin sites.
26 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002

Figure 11. The relation between total suspended solids and turbidity, 

Johnson Creek and Kelley Creek, Oregon, 2001–03.

1989–90 samples for which a turbidity was measured, to 

derive an estimated TSS concentration.

Relation of Organochlorine Pesticides to Total 

Suspended Solids

The relationship between organochlorine compounds 

and total suspended solids (either measured or estimated) 

was explored for the data sets from the 1989–90 and 2001–

02 time periods. Both the USGS and ODEQ data were used 

for this analysis. Total DDT and TSS were positively correlated, and there was a decrease in total DDT relative to 

TSS from the 1989–90 period to the 2001–02 period (fig.

12). The relation of total DDT and TSS was more linear in 

2001–02 than 1989–90 probably because most of the 

recent samples were from a single storm event, whereas 

the 1989–90 samples were from two high-flow events. 

The total DDT/TSS relation in the upper Johnson 

Creek Basin is shown in figure 12A. The older data are 

from the Regner Road site (RM 15.8) and the newer data 

are from the Palmblad Road site (RM 17.2). The land 

cover upstream of each of these sites is similar, although 

the area upstream from the Palmblad Road site has a 

slightly larger agricultural percentage (table 2, fig. 2). The 

data point representing a TSS value of 1,190 mg/L is 

shown on the graph, but it was not used in the regression 

because the primary interest was in determining the minimum threshold concentration of TSS that would be associated with exceedance of the Oregon chronic water-quality 

criterion for total DDT. For the Palmblad Road site, the 

TSS value that would correspond to the total DDT waterquality criterion of 0.001 μg/l was 8 mg/L TSS (table 10). 

The correlation coefficient for the regression was 0.78. 

Based on these data, if TSS could be limited to this concentration, the Oregon chronic freshwater criterion for 

total DDT would not be exceeded.

Similar data are shown in figure 12B for Johnson 

Creek at Sycamore (RM 10.2). For the 2002 data, the correlation coefficient was 0.89 and, using the regression 

equation, if the TSS were less than 18 mg/L at this site, 

then the Oregon chronic freshwater criterion for total DDT 

would not be exceeded (table 10). 

The relation between total DDT and TSS in the 

lower part of the Johnson Creek Basin is portrayed in figure 12C. Data from three sites were combined for the 

regression displayed for the total DDT/TSS relation: 

Johnson Creek at SE 45th Avenue (RM 3.2), Johnson 

Creek at Milwaukie (RM 0.7), and Johnson Creek at SE 

17th Avenue (RM 0.3). Data were combined because there 

were only small differences in stream discharge (fig. 3), 

land cover (table 2), and total DDT load (fig. 9). For the 

1989–90 sampling, similar land cover enabled grouping 

the samples at SE Stanley Avenue (RM 3.6) and at SE 44th 

Avenue (RM 3.0) with those at the Milwaukie gage. The 

correlation coefficient for 2001–02 was only 0.28, meaning that a relatively small portion of the variation was 

explained by the regression. One reason is that, as stated 

earlier, the peak of the March 2002 storm was not fully 

sampled in the lower part of the basin. Another reason for 

the poor relation is that concentrations of total DDT were 

low, with 3 of the 14 samples being below the detection 

level. (Nondetections were treated as zero values for this 

analysis.) Using the resulting regression, a TSS of lessthan or equal to 15 mg/L would need to be maintained in 

the lower basin to meet the Oregon chronic freshwater criteria for total DDT (table 10). As stated before, however, 

the confidence in this relation is not high.

Relative to TSS, there was up to an order-of-magnitude decrease in the concentrations of total DDT for 2001–

02 when compared to data from 1989–90. That is, for a 

given TSS concentration, the concentration of total DDT 

in 2001–02 was up to 10 times smaller than in 1989–90. 

This trend of decreased total DDT for a given mass of sediment over a decade timespan has also been observed in 

the Yakima River Basin, Washington (Rinella and others, 

1999).

The decrease over time of total DDT relative to TSS 

in the Johnson Creek Basin may have been due to several 

factors. First, some DDX may have been transported 

through the river system. These compounds were applied 

to plants and to the soil surface and some of the pesticide 

may have left the basin associated with sediment export 

during streamflow. Second, disturbance of noncontaminated soils may have in effect diluted the concentration 

of total DDT relative to TSS. Third, DDX may have 

degraded, although as indicated in the discussion of DDX 

concentrations, the persistence of the parent compound 
Table 9. Organochlorine-compound and other water-quality data collected and analyzed by the City of Portland, Oregon, Kelley Creek, 200[Map ID refers to the number on figure 1; ft3/s, cubic feet per second; mg/L, milligrams per liter; μg/L, micrograms per liter; NA, not available; NTU, nephelometric <, not detected at indicated concentration; E, estimated below minimum detection level; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethylDDT, dichlorodiphenyltrichloroethane]

Map ID Site Name Date and time

Discharge

(ft3/s) Turbidity (NTU)

Total 

suspended 

solids

(mg/L)

Aldrin

(μg/L)

Chlorpyrifos 

(μg/L)

p,p'-DDD 

(μg/L)

p,p'-DDE

(μg/L)

p,p'-DDD + p,p'-

DDE, rounded

(μg/L)

Di

(

5 Kelley Creek at RM 2.5 1/7/02 9:55 NA NA 20 <0.0003 E0.00026 0.0009 E0.0001 0.001 0.5 Kelley Creek at RM 2.5 3/6/02 9:20 NA NA 135 E.00019 .0017 .0004 .0023 .003 .5 Kelley Creek at RM 2.5 6/4/02 9:07 NA NA 17 E.00002 E.0003 <.00039 <.00039 0 <.5 Kelley Creek at RM 2.5 9/5/02 9:55 NA 29 2 E.00002 E.00027 E.00001 .0011 .001 E.5 Kelley Creek at RM 2.5 12/12/02 13:34 NA 21 3 <.0013 NA <.0013 E.00024 .0002 E.5 Kelley Creek at RM 2.5 1/29/03 9:15 NA 18 8.2 <.0012 NA <.0012 E.000096 .0001 E.6 Kelley Creek at RM 1.2 1/7/02 10:35 NA NA 15 <.0003 .0015 .0023 .0031 .005 .6 Kelley Creek at RM 1.2 3/6/02 9:45 NA NA 139 .0006 .0060 .0083 .0200 .028 .6 Kelley Creek at RM 1.2 6/4/02 9:33 NA NA 3 E.00003 .0196 <.0003 .0034 .004 .6 Kelley Creek at RM 1.2 9/5/02 10:35 NA 20 8.9 .0016 .0302 .0048 .0104 .015 .6 Kelley Creek at RM 1.2 12/12/02 13:50 NA 16 3 <.0012 NA .0018 .0034 .005 .6 Kelley Creek at RM 1.2 1/29/03 9:33 NA 50 57.7 <.0012 NA .0017 .0059 .008 .7 Clatsop Creek (tributary) 1/7/02 11:20 NA NA 19 <.0003 E.00045 .0010 .0004 .001 .7 Clatsop Creek (tributary) 3/6/02 10:10 NA NA 161 .0011 .0053 .0019 .0014 .003 .7 Clatsop Creek (tributary) 6/4/02 9:50 NA NA 3.2 <.0002 <.001 <.0003 <.0003 0 <.7 Clatsop Creek (tributary) 9/5/02 11:20 NA 6.3 2.8 .0008 E.00087 E.00013 E.00002 .0002 .7 Clatsop Creek (tributary) 12/12/02 14:37 NA 16 18 <.0012 NA E.00091 E.00014 .001 <.7 Clatsop Creek (tributary) 1/29/03 9:53 NA 30 22 <.0012 NA <.0012 E.0001 .0001 E.
Map ID Site Name Date and time Discharge (ft3/) Turbidity (NTU) Total suspended solids (mg/L) Aldrin (μg/L) Chlorpyrifos (μg/L) p,p'-DDD (μg/L) p,p'-DDE (μg/L) p,p'-DDD + p,p'- DDE, rounded (μg/L) Di

(

8 Kelley Creek at RM 0.5 1/7/02 10:00 NA NA 24.4 <0.0003 0.0042 0.0019 0.0020 0.004 0.8 Kelley Creek at RM 0.5 3/6/02 10:34 NA NA 157 .0021 .0072 .0051 .0130 .018 .8 Kelley Creek at RM 0.5 6/4/02 10:11 NA NA 2.8 <.0003 .0067 <.0004 <.00039 0 .8 Kelley Creek at RM 0.5 9/5/02 10:00 NA NA 1 .0007 .0009 .0009 .0010 .002 .8 Kelley Creek at RM 0.5 12/12/02 14:05 NA 12 1 <.0012 NA E.0005 E.001 .002 .8 Kelley Creek at RM 0.5 1/29/03 10:28 NA 21 15 <.0011 NA E.00055 E.001 .002 .9 Kelley Creek at SE 159th Drive, station 14211499 1/7/02 11:40 63 NA 18 <.0003 .0014 .0015 .0019 .003 .9 Kelley Creek at SE 159th Drive, station 14211499 3/6/02 10:50 190 NA 154 .0025 .0046 .0065 .0128 .019 .9 Kelley Creek at SE 159th Drive, station 14211499 6/4/02 10:33 .51 NA 2.8 <.00026 .0053 <.00037 <.00037 0 .9 Kelley Creek at SE 159th 

Drive, station 14211499

9/5/02 11:40 .18 5.7 2 .0007 .0078 .0007 .0010 .002 .

9 Kelley Creek at SE 159th 

Drive, station 14211499

12/12/02 14:20 1.7 11 2 E.00013 NA E.0004 E.00074 .001 .

9 Kelley Creek at SE 159th 

Drive, station 14211499

1/29/03 10:10 19 22 16 <.0012 NA E.00038 E.00098 .001 .

Table 9. Organochlorine-compound and other water-quality data collected and analyzed by the City of Portland, Oregon, Kelley Creek, 200[Map ID refers to the number on figure 1; ft3/s, cubic feet per second; mg/L, milligrams per liter; μg/L, micrograms per liter; NA, not available; NTU, nephelometric 

<, not detected at indicated concentration; E, estimated below minimum detection level; DDD, dichlorodiphenyldichloroethane; DDE, dichlorodiphenyldichloroethyl

DDT, dichlorodiphenyltrichloroethane]
Results 29

Figure 12. The relation between total DDT and total suspended solids, Johnson Creek Basin, Oregon, 1989–2002. A, upper basin sites; B, middle basin

site; C, lower basin sites.
Table 10. Maximum concentration of total suspended solids associated with the exceedance of the water-quality criterion for total 

DDT, Johnson Creek Basin, Oregon.

[Map ID refers to the number on figure 1; mg/L, milligrams per liter; TSS, total suspended solids; DDT, dichlorodiphenyltrichloroethane]

Map ID Site name

Johnson 

Creek river 

mile

Sample size 

for regression

Total suspended solids 

maximum concentration

(mg/L)

Correlation coefficient of linear 

regression, TSS versus total 

DDT

1 Johnson Creek at Palmblad Road 17.2 7 8 0.78

10 Johnson Creek at Sycamore 10.2 6 18 .89

14 Johnson Creek at SE 45th Avenue 3.2

1 Johnson Creek at Milwaukie 0.7 14 15 .28

18 Johnson Creek at SE 17th Avenue 0.3

30 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002

1

Combined samples from sites (Map ID) 14, 17, and 18.

17

DDT indicates degradation may not be a dominant process 

controlling the decrease of DDX in the Johnson Creek 

Basin. 

In general, the TSS concentrations were smaller in 

the 2001–02 data set than the estimates of TSS in 1989–90. 

The decrease in TSS may have been due to the nature of 

the 2002 storm that was sampled—it was not as large a 

storm as the December 1989 storm and was similar in 

magnitude to the January 1990 storm. Other factors, such 

as precipitation intensity and geographic distribution of 

precipitation and differences in the distribution of bare 

ground or otherwise erodible soils in the basin, could significantly affect the delivery of sediments (either contaminated or noncontaminated) to the stream. In addition, 

changes in land use, such as conversion of agricultural 

lands to residential development, may have affected the 

TSS concentration during a given storm. 

As discussed earlier in this report, dieldrin was not 

well correlated to total DDT, and one explanation for this 

is the difference in the solubility of DDX and dieldrin in 

water. Using similar methods as in the above section, 

dieldrin concentrations in the Johnson Creek Basin over 

the past decade were compared to TSS concentrations. In 

general, the dieldrin concentration was less for a given 

TSS concentration in 2001–02 than in 1989–90 (tables 6 

and 8). For the 2001–02 data set, the correlation between 

dieldrin and TSS is weak, so no direct estimator for dieldrin can be made based on TSS. The absence of a relationship between dieldrin and TSS indicates that controlling 

sediment in the stream may not control dieldrin in Johnson 

Creek.

Organochlorine Pesticides in Kelley Creek

Unfiltered water samples were collected from Kelley 

Creek (a tributary to Johnson Creek) and Clatsop Creek (a 

tributary to Kelley Creek) at five locations on 6 days 

between January 2002 and January 2003. The sampling 

locations are shown in figure 1 and land cover data are 

listed in table 2 and shown in figure 2. Listed from 

upstream to downstream, the sampling sites are Kelley 

Creek at RM 2.5, Kelley Creek at RM 1.2, Clatsop Creek 

near the mouth, Kelley Creek at RM 0.5, and the mouth of 

Kelley Creek (USGS gaging station number 14211499). 

Few flow data were available for Kelley Creek. The USGS 

gage was located at the mouth of the creek, which was the 

location of the most downstream sampling. No flow data 

were available for the sampling locations upstream of the 

gage site. 

Although these samples were not part of the USGS 

cooperative study, discussion of them is included for several reasons: Kelley Creek has the largest drainage area of 

any tributary to Johnson Creek, the results (table 9) provide insight into the occurrence of organochlorine pesticides in this basin relative to land cover, and some of the 

results can be compared to samples collected from Kelley 

Creek by the USGS in 1989–90 that contained DDX (table 

8). 

The sampling and analysis were done by the City of 

Portland Bureau of Environmental Services and their contractors. Analytical data were available for several compounds, but due to quality-control considerations only two 

of the DDT metabolites and dieldrin are discussed here. 

Analytical problems occurred with several of the samples, 

as indicated by high laboratory-spike recoveries (140–
Results 31

476%) for certain constituents. For this reason, of the six 

DDT and metabolite compounds analyzed in 2002–03 

(p,p’-DDT, p,p’-DDE, p,p’-DDD, o,p’-DDT, o,p’-DDE, 

and o,p’-DDD) only p,p’-DDE and p,p’-DDD [hereafter 

combined and referred to as “p,p’-DDE + p,p’-DDD”] are 

discussed in this section. For these reasons, this analysis 

should be considered more of a qualitative comparison of 

the occurrence of organochlorine compounds through time 

and space in Kelley Creek.

Samples were collected from Kelley Creek in 2002 

on January 7, March 6, June 4, September 5, and December 12, and on January 29, 2003, under a variety of streamflow conditions (fig. 13). The samples collected on 

January 7, 2002, and March 6, 2002, are considered 

medium- to high-flow samples; the discharge at the mouth 

of Kelley Creek was 60 ft3/s and 200 ft3/s, respectively. 

These samples were collected during storm periods, with 

more than 1 inch of precipitation at the Pleasant Valley 

School rain gage over the 3 days prior to the sampling on 

each day (City of Portland, Bureau of Environmental Services, 2002b). Samples from June and September 2002, 

were collected during low-flow conditions. The discharge 

at the mouth of the creek was less than 1 ft3/s and no 

precipitation fell for several days prior to the sampling. 

The sample collected on December 12, 2002, reflected a 

fairly dry antecedent condition. Prior to the sampling, 0.9 

inch of precipitation fell in the 3 days, but the flow (less 

than 2 ft3/s at the mouth of the Kelley Creek) had not 

exceeded this level for more than 2 days over the past 5 

months. The sampling of January 29, 2003, was done 

when the flow at the mouth of the creek was about 20 ft3/s, 

medium in the range of flows associated with samples over 

the previous year, and occurred after several days of intermittent rain, with 0.2 inches over the previous 3 days.

In general, as with other samples in the Johnson 

Creek Basin, p,p’-DDE + p,p’-DDD concentrations were 

positively correlated with TSS, although as a whole, the 

2002–03 data are scattered. When the sample results were 

separated by site (fig. 14), several patterns emerged. The 

samples collected from the most upstream location, Kelley 

Creek at RM 2.5, and from the mouth of Clatsop Creek had 

the lowest concentrations of p,p’-DDE + p,p’-DDD relative to TSS of any sites sampled in the Kelley Creek Basin. 

The land cover upstream of both of these locations is primarily forest (fig. 2, table 2). The forest and meadow and 

grass areas comprise 87 percent and 68 percent of the areas 

upstream of the Kelley Creek at RM 2.5 and Clatsop Creek 

sites, respectively. Also significant is the low agricultural 

component, only 11 percent and 8 percent, respectively. 

The areas upstream of these two sites have the lowest percentage of agricultural and highest percentage of forested 

lands relative to others in the Johnson Creek Basin. Clatsop Creek has a more urban component than the upper 

Kelley Creek area. Recently disturbed lands associated 

with urban development, in conjunction with steep slopes, 

may account for the relatively high TSS concentration during the March 2002 sampling, but regardless, neither area 

upstream of the sampling sites appears to be a significant 

source of p,p’-DDE + p,p’-DDD. The highest concentration observed at both of these sites was 0.003 μg/L, each 

during the March 2002 sampling. Of the total of 12 samples at these 2 locations, 6 were less than 0.001 μg/L of 

p,p’-DDE + p,p’-DDD, and 4 were at the 0.001 μg/L concentration. Several of the individual values were reported 

as estimates. 

In contrast to the upper Kelley Creek Basin and Clatsop Creek, the middle portion of Kelley Creek, defined as 

the part of the basin between RM 2.5 and RM 1.2, was a 

significant source of p,p’-DDE + p,p’-DDD. The agricultural component upstream of RM 1.2 was 41 percent, similar to the agricultural component of land cover in the upper 

Johnson Creek Basin. The primary type of agriculture in 

this area is currently (and possibly historically) in-ground 

and container nurseries. The combined concentration of 

p,p’-DDE + p,p’-DDD at Kelley Creek at RM 1.2 for each 

of the six samplings was equal to or greater than 0.004 

μg/L, with a maximum concentration of p,p’-DDE + p,p’-

DDD of 0.028 μg/L for the March 2002 event. All six samples exceeded the freshwater criterion for total DDT. In 

addition to the organochlorine pesticides noted above, 

dieldrin and endrin exceeded the freshwater chronic toxicity criteria in the Kelley Creek site at RM 1.2, based on 

instantaneous concentrations (table 9). 

Concentrations in the lower part of the Kelley Creek 

Basin, represented by samples at RM 0.5 and at the mouth 

of Kelley Creek, may be indicative of a dilution effect of 

organochlorine-compound- and sediment-laden waters 

coming from the middle basin. Both locations were downstream from Clatsop Creek. The distribution of land-cover 

types becomes increasingly urban. However, upstream 

agricultural and forest components still contribute, and the 

distribution of land cover at the mouth of the creek was 

similar to that of the Johnson Creek Basin upstream from 

Regner Road. The concentration of p,p’-DDE + p,p’-DDD 

at RM 0.5 and at the mouth appeared to be less than at RM 

1.2 for a given concentration of TSS (fig. 14): of the 12 

samples, 2 did not contain p,p’-DDE or p,p’-DDD at concentrations greater than the detection level, and the maximum combined concentration was 0.019 μg/L, again 

occurring during the March 2002 sampling. Without 

stream discharge data, it was not possible to determine if 

additional loading of these organochlorine compounds 

occurs downstream from RM 1.2.

Dieldrin data collected in 2002–03 in the Kelley 

Creek Basin also indicated spatial trends. As with the p,p’-

DDE + p,p’-DDD analysis, dieldrin concentrations were 

relatively low at the sites on Kelley Creek at RM 2.5 and 

on Clatsop Creek (table 9). The average concentration of 

the six samples at each site (using estimated values as-is 

and setting less-than values to zero) at Kelley Creek at RM 

2.5 and Clatsop Creek was 0.0007 and 0.0011 μg/L, 
32 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002

Figure 13. Daily mean discharge and discharge at time of sampling at Kelley Creek, Oregon, and daily total precipitation, October 2001 to January 2003.

respectively. In contrast, the average concentration in 

Kelley Creek at RM 1.2 was more than 20 times higher, at 

0.0181 μg/L. Average concentrations of dieldrin at RM 0.5 

and at the mouth of Kelley Creek were 0.0104, and 0.0087 

μg/L respectively. The sharp increase at RM 1.2 compared 

to RM 2.5 indicated a likely source between these two 

locations. Load comparisons could not be done with these 

data due to lack of flow data at all but the site at the mouth 

of the creek. Although p,p’-DDE + p,p’-DDD was correlated to TSS, no such relation could be developed for 

dieldrin.

Dieldrin concentrations in Kelley Creek, when compared to the concentration of p,p’-DDE + p,p’-DDD, were 

higher than observed at sites on Johnson Creek. The dieldrin concentration of several samples was higher than that 

of p,p’-DDE + p,p’-DDD, compared to the general trend 

observed on Johnson Creek, where the dieldrin concentration was less than half of the total DDT. The reason for this 

is unknown. 

In addition to spatial differences in the distribution 

of p,p’-DDE + p,p’-DDD in the Kelley Creek Basin, some 

evidence indicates a decrease in these compounds relative 

to TSS over time. Samples taken in 1989 and 1990 at the 

mouth of Kelley Creek indicate a higher concentration of 

p,p’-DDE + p,p’-DDD relative to TSS than samples taken 

in 2002–03 (tables 8 and 9, fig. 14). The TSS concentrations for the 1989–90 samples were estimated using methods described above. Although the difference in pesticide 

concentration relative to a similar TSS concentration for 

these two samples indicate about a twofold decline, other 

factors such as the magnitude of the storms, antecedent 

conditions, and position on the flow hydrograph may have 

an effect on the comparability of the results.

Implications for Future Study

A major shortcoming of the present study is that it 

contains only data from a single storm, which is not optimal for predicting the concentrations and loads of contaminants under various other conditions. A future monitoring 

program to estimate organochlorine-pesticide loads in 

Johnson Creek and its tributaries could be accomplished 

by installing continuous streamflow and turbidity monitors 

in conjunction with additional sampling for TSS/sediment 

and organochlorine-compounds. An alternate method of 

measuring and expressing suspended solids is suspendedsediment concentration. This method is reliable regardless 

of the amount of sand-size material in the samples (Gray 

and others, 2000), and for future studies use of this technique could be considered.

Four USGS streamflow-gaging sites already exist 

(fig. 1, table 1) and discharge data from these sites are 
Implications for Future Study 33

Figure 14. The relation between p,p’-DDE + p,p’-DDD concentration and total suspended solids, Kelley Creek, Oregon, 1989–90 and 2001–03.

necessary to calculate the load of any constituent. 

Turbidity can be used as a surrogate to predict the 

concentrations of TSS or suspended sediment, which in 

turn could be used to predict total DDT or fecal-indicator 

bacteria because these constituents are often sorbed to or 

associated with the sediment particles. Provided that it is 

done carefully, the measurement of turbidity is straightforward and inexpensive compared to the sampling and 

analysis for organochlorine compounds. Continuously 

deployed turbidimeters are becoming more reliable and 

accurate, and when added to present-day stream-gaging 

stations in the basin, the turbidity data could be available 

in real-time along with the streamflow data. A turbidity 

monitoring program should include documented, 

consistent techniques and instruments, along with sound 

data-management and storage procedures. There may be a 

need for auto-samplers to automatically sample for 

organochlorine pesticides and sediment during storm 

events. Some existing TMDLs for organochlorine 

pesticides target turbidity as the surrogate constituent for 

regulation, for reasons mentioned above. Therefore, 

monitoring of turbidity may have the added benefit of 

evaluating compliance to State of Oregon regulations.

A monitoring program could be designed to concentrate on the upland areas, including Johnson Creek 

upstream of Palmblad Road, and the middle Kelley Creek 

Basin. The data in this report showed that organochlorinepesticide concentrations were highest in the upper Johnson 

Creek Basin, both in samples from 2002 and samples from 

1989–90. The lack of discharge data, except at the mouth 

of Kelley Creek, and quality-assurance problems in the 

laboratory analyses made it difficult to understand the 

loading of organochlorine compounds in Kelley Creek. 

Finer definition of the occurrence, loading, and possible 

source areas of organochlorine pesticides could be accomplished if more streamflow, turbidity, and organochlorine-
34 Organochlorine Pesticides in the Johnson Creek Basin, Oregon, 1988–2002

pesticide data were collected. Additional data on the 

occurrence of dieldrin are needed because this study indicated that it is not reasonable to predict dieldrin concentrations based on TSS.

Fish tissue analysis for organochlorine compounds 

would be helpful to determine the health risk associated 

with fish consumption by humans and wildlife. A previous 

study of Johnson Creek using semipermeable membrane 

devices to simulate bioaccumulation showed that organochlorine compounds such as DDT and dieldrin were 

accumulated in those devices in Johnson Creek (McCarthy 

and Gale, 1999).

Structural measures (for example, wetlands or offchannel settling ponds) could be used to trap sediment, and 

consequently reduce mobilization of organochlorine compounds in the stream. Evaluating these measures was not 

part of the scope of the present report, but they were 

described in an earlier work (Edwards, 1994). Steeply 

sloped areas with the historical use of organochlorine compounds are potential source areas for organochlorine compounds. If structural measures were implemented in some 

of these areas, a water-quality monitoring program would 

be needed to evaluate their effectiveness.

Summary and Conclusions

Unfiltered water samples were collected from several 

sites in the Johnson Creek Basin and analyzed to better 

understand the extent of organochlorine-compound contamination, explore the relationship of certain organochlorine compounds to total suspended solids, and assess 

the changes in organochlorine-compound concentrations 

over time. Four to six samples were taken at each of four 

sites on Johnson Creek during a storm in March 2002 and 

analyzed by the USGS National Water Quality Laboratory. 

In addition, two storm drains were sampled multiple times. 

Samples taken by the Oregon Department of Environmental Quality (ODEQ) at five sites on 3 days in winter, 2001–

02 also were analyzed, providing organochlorine-pesticide 

data for nonstorm periods. In addition, samples were taken 

at five stream sites in the Kelley Creek Basin (a tributary 

to Johnson Creek) by the City of Portland on 6 days in 

2002–03. Samples collected by ODEQ were analyzed by 

their laboratory, and samples from Kelley Creek were analyzed by private laboratories. 

Quality-control data from laboratory blanks, replicate samples, and organic-chemical surrogates analyzed by 

both the USGS and ODEQ laboratories indicated that the 

data quality was within acceptable ranges. Although the 

USGS laboratory appeared to have a low bias and the 

ODEQ laboratory appeared to have a high bias with 

respect to organochlorine-compound concentrations, the 

data were usable for assessments of potential source areas 

and loading. Samples analyzed by the private laboratory 

may have been subjected to some contamination or interference; for this reason, only some of those analytical 

results were discussed in this report.

Organochlorine pesticides were detected at five of 

six sites sampled by the USGS in March 2002 and at all 

sites sampled by the ODEQ in 2001 and 2002. State of 

Oregon chronic freshwater criteria were potentially 

exceeded for total DDT, dieldrin, chlordane, and total 

PCB. (The water-quality data did not cover a long enough 

time period—4 days—to determine if an exceedance did 

occur). Total DDT, composed of hydrophobic compounds, 

is commonly associated with sediment in the stream. There 

was a positive correlation between concentration of total 

DDT with turbidity (the sediment parameter analyzed in 

the 1989–90 sampling), as well as with total suspended 

solids (the sediment parameter analyzed in the 2001–03 

sampling). The 2001–03 sampling included analyses for 

both turbidity and TSS, providing a relation between these 

two sediment measures, and a common basis (estimated 

TSS) for comparison to the 1989–90 data. The concentrations of total DDT relative to TSS has decreased markedly 

from a decade ago. In general, total DDT concentration 

was an order of magnitude less in 2002 compared to 1989–

90. A statistically significant relation could not be established between dieldrin and TSS. 

Loads of total DDT and dieldrin were calculated as 

organochlorine-pesticide concentration multiplied by 

stream discharge and were investigated to assess possible 

sources and sinks of the compounds. The largest instantaneous loads of total DDT and dieldrin occurred at the 

Palmblad Road site (76 grams per day and 23 grams per 

day, respectively). These loads indicate a possible source 

of organochlorine pesticides in the drainage basin 

upstream of the Palmblad Road site, which has 50% agricultural land cover, the highest percentage agricultural 

land cover of any sampled site. This land was probably 

agricultural land in the past, and the historical use of nowbanned organochlorine pesticides in combination with soil 

erosion from current practices may be responsible for the 

current loads of these compounds.

Regression equations developed for estimating total 

DDT based on TSS concentration allowed the calculation 

of threshold TSS concentrations associated with the 

exceedance of the freshwater criteria for total DDT. At the 

Palmblad Road site, a TSS concentration larger than 

8 mg/L could result in the exceedance of the standard, 

while a TSS concentration larger than 18 mg/L and 

15 mg/L could result in exceedance of the standard at the 

Sycamore and Milwaukie sites, respectively. Again, this 

indicates a potential upstream source of DDX, with DDXcontaminated sediments mixing with uncontaminated sediments lower in the basin.

Samples from Kelley Creek, a tributary to Johnson 

Creek, illustrated spatial and temporal trends in p,p’-DDE 

+ p,p’-DDD. Results for the Kelley Creek samples were 

treated separately in this report due to possible quality-
References Cited 35

assurance problems. Due to this shortcoming, comparisons 

made among the Kelley Creek sites in 2002–03, as well as 

comparison with data collected in 1989–90 were considered qualitative. Neither the headwaters of Kelley Creek 

(upstream of RM 2.5), nor Clatsop Creek (a tributary to 

Kelley Creek) appeared to be sources of p,p’-DDE + p,p’-

DDD or of dieldrin. Samples taken at RM 1.2 had elevated 

p,p’-DDE + p,p’-DDD and dieldrin concentrations indicating a source of those compounds in the middle reaches 

(between RM 2.5 and RM 1.2). Samples taken at RM 0.5 

and at the mouth of the creek indicate possible dilution of 

higher concentrations from this middle reach. The concentration of p,p’-DDE + p,p’-DDD relative to TSS appears to 

have decreased since the sampling in 1989–90, based on a 

very limited amount of data.

Future studies in the Johnson Creek Basin could 

include continuous monitoring of streamflow and turbidity, and additional sampling for organochlorine compounds. Further studies of the agricultural areas upstream 

of the Palmblad Road site and in the Kelley Creek Basin 

would be useful, especially as some of these areas undergo 

changes in land use. 

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