science for a changing world

TUALATIN RIVER

Summer Creek

Ball Cre e k

Ash

Creek

Fanno

Creek

Sylvan

Cr.

Pendleton Cr.

Vermont

Cre ek

Fanno

Cr.

Lake Oswego

Tigard

26

5

5 F2

F3

F1

Cedar Mill Cre ek

U.S. Department of the Interior

U.S. Geological Survey

Prepared in cooperation

with CLEAN WATER SERVICES

Phosphorus and E. coli and Their Relation to

Selected Constituents During Storm Runoff

Conditions in Fanno Creek, Oregon, 1998-99

Water-Resources Investigations Report 02-4232

Fanno Creek at 56th Avenue 

Fanno Creek at Scholls Ferry Road near Allen Boulevard 

Fanno Creek at Durham Road 

Photographs of Fanno Creek at 56th Avenue and Fanno Creek at Scholls Ferry Road near 

Allen Boulevard were taken by Steward Rounds, U.S. Geological Survey. Photograph of 

Fanno Creek at Durham Road was taken by Dennis A. Wentz, U.S. Geological Survey
Phosphorus and E. coli and Their Relation to 

Selected Constituents During Storm Runoff 

Conditions in Fanno Creek, Oregon, 1998–99

By Chauncey W. Anderson and Stewart A. Rounds

Prepared in cooperation with

CLEAN WATER SERVICES

Portland, Oregon

2003

Water-Resources Investigations Report 02-4232

U.S. GEOLOGICAL SURVEY
For additional information write to:

District Chief

U.S. Geological Survey

10615 S.E. Cherry Blossom Drive

Portland, Oregon 97216-3159

Email: info-or@usgs.gov

Internet: http://oregon.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.

Copies of this report can be purchased from:

U.S. Geological Survey

Information Services

Building 810

Box 25286, Federal Center

Denver, CO 80225-0286

U.S. DEPARTMENT OF THE INTERIOR

GALE A. NORTON, Secretary

U.S. GEOLOGICAL SURVEY

Charles G. Groat, Director

Suggested citation:

Anderson, C.W., and Rounds, S.A., 2003, Phosphorus and E. coli and their relation to selected constituents during 

storm runoff conditions in Fanno Creek, Oregon, 1998–99: U.S. Geological Survey Water-Resources Investigations 

Report 02-4232, 34 p.
Contents iii

CONTENTS

Significant Findings ............................................................................................................................................. 1

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

Purpose and Scope ...................................................................................................................................... 3

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

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

Methods and Quality Assurance .......................................................................................................................... 5

Discharge and Water Quality...................................................................................................................... 5

Quality Assurance Results .......................................................................................................................... 7

Results .................................................................................................................................................................. 7

Storms Sampled .......................................................................................................................................... 7

Water Quality.............................................................................................................................................. 9

Discharge ........................................................................................................................................... 9

Solids.................................................................................................................................................. 9

Biochemical Oxygen Demand ........................................................................................................... 14

Bacteria .............................................................................................................................................. 14

Bacterial sources ....................................................................................................................... 15

Phosphorus......................................................................................................................................... 16

Nitrogen ............................................................................................................................................. 20

Summary .............................................................................................................................................................. 23

References Cited .................................................................................................................................................. 24

Appendix A.—Quality Assurance Program......................................................................................................... 27

Quality Assurance Samples......................................................................................................................... 27

Quality Assurance Results .......................................................................................................................... 28

Table A1. Replicate sample results and relative percent differences during storm samplings, 1998–99 .. 30

Appendix B.—Water quality data from Fanno Creek, Oregon............................................................................ 32
iv Figures

FIGURES

Figure 1. Map showing location of study area and storm sampling sites, Fanno Creek, Oregon..................... 4

Figure 2. Hydrographs showing discharge, precipitation, and sampling times at 

56th Avenue (14206900) and at Durham Road (14206950) during three storms, 

Fanno Creek, Oregon, June 1998 to December 1999 ........................................................................ 6

Figure 3. Hydrograph showing discharge and storms sampled at Durham Road (14206950), 

Fanno Creek, Oregon, April 1998 to April 2000............................................................................... 8

Figure 4. Graph showing correlation of total solids (TS) with total suspended solids (TSS), 

total volatile suspended solids (TVSS), total dissolved solids (TDS), and 

total phosphorus (TP) at all sampling sites during three storms, Fanno Creek, 

June 1998 to December 1999............................................................................................................. 11

Figure 5. Hydrograph showing discharge and total solids concentrations at 

Durham Road (14206900) during storm 1, Fanno Creek, Oregon, June 23-25, 1998....................... 11

Figure 6. Hydrographs showing relation of instantaneous concentrations and loads with 

discharge at all sampling sites during storm 1, Fanno Creek, Oregon, June 23-25, 1998................. 12

Figure 7. Graphs showing cumulative loads and yields at 56th Avenue (upstream site; 14206900) 

and at Durham Road (downstream site; 14206950) during storm 1, Fanno Creek, 

Oregon, June 23–25, 1998 ................................................................................................................. 13

Figure 8. Hydrographs showing discharge and total solids (TS) concentrations at 

56th Avenue (14206900) and at Durham Road (14206950) during storm 3, 

Fanno Creek, Oregon, December 5-8, 1999 ...................................................................................... 13

Figure 9. Boxplots showing E. coli bacteria concentrations at each sampling site during 

three storms, Fanno Creek, Oregon, June 1998 to December 1999 .................................................. 14

Figure 10. Boxplots showing total phosphorus (TP) concentrations at each sampling site 

during three storms, Fanno Creek, June 1998 to December 1999..................................................... 16

Figure 11. Hydrographs showing variability of total phosphorus (TP) and soluble reactive 

phosphorus (SRP) concentrations with discharge at 56th Avenue (14206900) 

and at Durham Road (14206950) during storm 1, Fanno Creek, Oregon, June 23-25, 1998............ 18

Figure 12. Graph showing seasonal patterns in monthly phosphorus concentrations in 

Fanno Creek, Oregon, 1991–2001..................................................................................................... 19

Figure 13. Graph showing relation of soluble fraction of phosphorus with discharge at all 

sampling sites during three storms, Fanno Creek, Oregon, June 1998 to December 1999 ............... 19

Figure 14. Hydrograph showing relation of total phosphorus (TP) concentrations with 

discharge at all sampling sites during storm 1, Fanno Creek, Oregon, June 23-25, 1998................. 20

Figure 15. Boxplots showing nitrate nitrogen concentrations at each sampling site during 

three storms in Fanno Creek, Oregon, June 1998 to December 1999 ............................................... 20

Figure 16. Graph showing seasonal patterns in monthly nitrate and ammonia nitrogen 

concentrations in Fanno Creek, Oregon, 1991–2001......................................................................... 21

Figure 17. Hydrographs showing nitrate concentrations at 56th Avenue (14206900) during 

three storms, Fanno Creek, Oregon, June 1998 to December 1999 .................................................. 22
Tables v

TABLES

Table 1. Storm sampling sites in Fanno Creek, Oregon, 1998–99 .................................................................. 5

Table 2. Constituents analyzed from water samples collected during stormflows in 

Fanno Creek, Oregon, 1998–99......................................................................................................... 7

Table 3. Storm dates and number of samples at each site in the Fanno Creek drainage basin, Oregon.......... 8

Table 4. Correlations for selected water-quality constituents during storm conditions in 

Fanno Creek, Oregon, 1998–99......................................................................................................... 10
vi Glossary

GLOSSARY

Terms and abbreviations, as used in this report

BOD5 5-day biochemical oxygen demand

BODrate First-order decay rate for biochemical oxygen demand

BODult Ultimate biochemical oxygen demand, or BOD when 

taken to steady dissolved-oxygen concentration

CWS Clean Water Services, formerly Unified Sewerage Agency

DO Dissolved Oxygen

E. coli Escherchia coli, a bacterium

hydrograph The pattern of water flow during a specified period of time

hysteresis A pattern of water-quality constituents having different 

concentrations for a given discharge depending on their 

sequence over a storm hydrograph. The pattern results in a 

loop when discharge is plotted against the constituent 

concentration

load The amount of material in transport in a stream, in units of 

mass per unit time

nitrification The oxidation of ammonia-nitrogen to nitrate nitrogen by 

microbes

nonpoint sources Input of materials from diffuse, poorly defined locations

NH3-N Ammonia nitrogen, analyzed in a filtered, undigested 

sample

NO3-N Nitrate nitrogen, analyzed in a filtered, undigested sample

NPDES National Pollutant Discharge Elimination System

ODEQ Oregon Department of Environmental Quality

p Probability

ρ, rho Spearman’s correlation coefficient, a nonparametric 

indicator of the degree of correlation between two 

variables

sediment oxygen demand The consumption of dissolved oxygen by various 

processes in streambed sediment, also known as SOD

SRP Soluble reactive phosphorus, analyzed in a filtered, 

undigested sample and usually dominated by 

orthophosphorus

TMDL Total Maximum Daily Load, a regulated amount of a 

constituent that can be transported by a stream. Required 

under the Clean Water Act for rivers and streams that do 

not meet water-quality standards under certain conditions

TP Total phosphorus, analyzed in an unfiltered, digested 

sample

trip blank A sample of analyte-free water prepared prior to a field 

trip, and transported and processed identically to other 
Glossary vii

environmental samples. Used to check for contamination 

in field transport and laboratory analysis of water samples

TS Total solids, the mass of all particulate materials in an 

aliquot of a water sample, upon evaporation at 103-105 

degrees Celsius. TS is inclusive of TSS, TVSS, and TDS 

(see below).

TDS Total dissolved solids, the portion of total solids that 

passes through a filter

TSS Total suspended solids, the portion of total solids retained 

on a filter

turbidity An optical measurement of the scattering of light in water 

TVSS Total volatile suspended solids, the portion of total 

suspended solids lost upon ignition at 550 oC

USA Unified Sewerage Agency, now Clean Water Services 

(CWS)

USEPA United States Environmental Protection Agency 

USGS United States Geological Survey

yield Mass of material derived from a given area upstream, in 

units of mass per area
viii Conversion Factors

CONVERSION FACTORS

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

°F= (1.8 °C)+32

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

°C= (°F-32)/1.8

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

milligram per liter is equivalent to one thousand micrograms per liter (μg/L). One microgram per liter 

is equivalent to “parts per billion.”

Bacterial concentrations in water are given in colonies per 100 milliliters (mL) of a water sample. 

Multiply By To obtain

Length

inch (in) 2.54 centimeter (cm)

inch (in) 25.4 millimeter (mm)

foot (ft) 0.3048 meter (m)

mile (mi) 1.609 kilometer (km)

Area

square mile (mi2) 259.0 hectare (ha)

square mile (mi2) 2.590 square kilometer (km2)

Volume

cubic foot (ft3) 0.02832 cubic meter (m3)

Flow Rate

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

Mass

ounce, avoirdupois (oz) 28.35 gram (g)

pound, avoirdupois (lb) 0.4536 kilogram (kg)

pound per day (lb/d) 0.4536 kilogram per day (kg/d)

pound per hour (lb/hr) 0.4536 kilogram per hour (kg/hr)

pound per square mile (lb/mi2) 0.4536 kilogram per square mile (kg/mi2)

ton per day (ton/d) 0.9072 metric ton per day (mton/d)
Significant Findings 1

Phosphorus and E. coli and Their Relation to Selected 

Constituents During Storm Runoff Conditions in 

Fanno Creek, Oregon, 1998–99

By Chauncey W. Anderson and Stewart A. Rounds

SIGNIFICANT FINDINGS

As part of an ongoing cooperative study between 

Clean Water Services of Washington County, Oregon, 

and the U.S. Geological Survey, water-quality data 

were collected from Fanno Creek, Oregon, during three 

storms from June 1998 to December 1999. Samples 

were collected over the discharge hydrograph from 

three sites during one summer storm, one fall storm, 

and one winter storm. From these data, the following 

conclusions were reached for water-quality conditions 

and processes in Fanno Creek during storm runoff:

• Discharge was significantly correlated with total 

solids (TS), total suspended solids (TSS), total 

volatile suspended solids (TVSS), turbidity, and 

total phosphorus (TP).

• Of the different fractions of TS measured, TS was 

most directly correlated with TSS.

• Rising limbs of discharge hydrographs had higher 

concentrations of sediment and TP, possibly 

indicating that sources were nearby (resuspension 

of streambed, bank erosion, close upland sources) 

and that available supplies limited downstream 

transport.

• Concentrations of sediment (TS, TSS), TP, and 

bacteria (E. coli) were greatest and most variable 

at the most upstream site. Peak bacterial loads 

were similar at upstream and downstream sites, so 

additional sources were not evident, or 

downstream sources were offset by settling or 

losses of bacteria from upstream.

• Biochemical oxygen demand during storms was 

primarily associated with decomposable materials 

on particulate matter.

• E. coli concentrations exceeded the State of 

Oregon single-sample water-quality standard of 

406 colonies/100 mL in almost all samples. E. coli 

concentrations measured during the summer storm 

were an order of magnitude greater than those 

measured during the fall or winter storms, 

primarily due to warmer water and less dilution 

during the summer storm.

• E. coli were correlated with suspended sediment 

(TSS and turbidity), indicating that they were 

either transported to streams attached to particles 

bound to resuspended streambed particles, or they 

had an affinity for particulate material in water. 

• TP concentrations exceeded both the 1998 and 

2001 Total Maximum Daily Load (TMDL) 

criterion concentrations in almost all samples.

• Soluble Reactive Phosphorus (SRP) in the stream 

may have originated primarily from ground-water 

discharge, whereas TP was mostly associated with 

particulates.
2 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99

INTRODUCTION

Water-quality problems in the Tualatin River 

Basin, Oregon, include low dissolved oxygen (DO), 

high pH, high water temperature, and high bacterial 

(Escherichia coli, or E. coli) counts, all of which 

episodically exceed State of Oregon water-quality 

standards. Excursions of pH typically are caused by 

algal blooms that grow in response to long travel times, 

warm water, and excessive nutrient inputs. In the 

reservoir system of the Tualatin River, low DO 

concentrations are most typically caused by sediment 

oxygen demand and long travel times in the absence of 

significant levels of photosynthesis and reaeration, 

although DO in the main stem also can be reduced by 

nitrification when ammonia concentrations are high 

(Rounds and Wood, 2001). In response to these and 

other water-quality problems, the State implemented 

Total Maximum Daily Loads (TMDLs) in 1988 for the 

Tualatin River Basin, as required under the Clean 

Water Act (Oregon Department of Environmental 

Quality, 1994a, 2001a). During 2001, the original 

phosphorus and ammonia TMDLs were revised, with 

new TMDLs added for water temperature, oxygenconsuming substances, and E. coli (Oregon 

Department of Environmental Quality, 2001b). 

In 1990, the U.S. Geological Survey (USGS) 

entered into a cooperative agreement with Clean Water 

Services (CWS — formerly the Unified Sewerage 

Agency) to investigate causes of water-quality 

problems in the river and evaluate alternatives for their 

management. Previous reports have described the 

TMDLs and USGS projects characterizing DO in the 

Tualatin River during winter (Kelly, 1997), nutrient 

sources and transport during low flows (Kelly and 

others, 1999), temperature modeling (Risley, 2000), 

sediment-oxygen demand (Rounds and Doyle, 1997), 

water-quality modeling (Rounds and Wood, 2001; 

Rounds and others, 1999), and phosphorus and bacteria 

in various tributaries during low-flow conditions 

(McCarthy, 2000).

Technological improvements and programmatic 

changes have reduced loads of phosphorus and 

ammonia to the Tualatin River from point sources since 

1991 (Rounds and Wood, 2001). However, because of 

continuing water-quality problems and ongoing 

urbanization, attention has increasingly turned to 

nonpoint sources for opportunities to further reduce 

contaminant loads. Tributary streams, which integrate 

nonpoint runoff from their entire watersheds, can be 

important transport pathways; however, water quality is 

a concern in some tributaries regardless of the effects 

on downstream receiving waters. Whereas the 1988 

TMDL considered tributaries as a source of the 

phosphorus that was causing problems in the main 

stem, the 2001 TMDL focuses on problems in both the 

tributaries and the main stem. For instance, in the 2001 

TMDL, Fanno Creek is allowed a summer median 

concentration of total phosphorus (TP) of 0.13 

milligram per liter (mg/L) (Oregon Department of 

Environmental Quality, 2001a), and its phosphorus 

load during summer is considered part of the total 

1,272 pounds allowed in the lower Tualatin during the 

same season. Thus, CWS and other resource managers 

are faced with the necessity of either controlling the 

concentration of TP in runoff or reducing the volume of 

runoff over the summer months. Loads of E. coli

bacteria from point sources also are regulated on a 

seasonal basis, with higher cumulative concentrations 

allowed from these sources during summer storms 

(12,000 counts/100 mL) than during winter storms 

(5,000 counts/100 mL) (Oregon Department of 

Environmental Quality, 2001a). The State Standard for 

E. coli bacteria in a single, instantaneous stream 

sample is 406 counts/100 mL, or a monthly geometric 

mean of 126 colonies/100 mL for multiple samplings. 

Chlorophyll a concentrations in Fanno Creek 

occasionally exceed the State’s action level of 15 

micrograms per liter (μg/L) (Oregon Department of 

Environmental Quality, 2001a), although 

concentrations appear to have been decreasing in recent 

years (Jan Miller, Clean Water Services, written 

commun., April 2002). Total volatile suspended solids 

(TVSS) is regulated in the Tualatin River TMDL for 

control of sediment oxygen demand.

McCarthy (2000) documented nutrients and 

bacteria concentrations in selected Tualatin River 

tributaries, including Fanno Creek, during summer 

low-flow conditions. Among her findings were that 

ground-water discharge could account for the 
Introduction 3

phosphorus concentrations measured at most sites in 

the subbasin, but that local sources other than ground 

water were evident, possibly including avian waste 

materials and sediments resuspended from off-channel 

ponds. E. coli concentrations also were elevated at 

70 percent of the sites sampled, possibly due to 

domestic pet and wildlife wastes, septic systems, or 

hobby farms. That study provided indications of the 

processes contributing nutrients during summer steady 

state, low-flow conditions, a period that is arguably the 

most sensitive regarding the effects of nutrients on 

eutrophication. Nonetheless, nutrients that enter creeks 

during other periods may be retained in the system, for 

example as particulate material in the bed sediments, 

and become biologically available during critical 

periods. Storm runoff is a significant process 

contributing sediment, nutrients, and bacteria to 

streams in urban areas, and likely provides part of the 

loads of these and other constituents to Fanno Creek.

Purpose and Scope

The purpose of this report is to characterize 

water quality, including sources and transport of 

nutrients and bacteria, during storm runoff conditions 

in the Fanno Creek Subbasin. Findings from this report 

ultimately will improve the understanding of dominant 

sources and transport processes in the basin and help 

improve water quality by strengthening the 

management of urban streams. During three storms 

from 1998 to 1999, data on nutrients, bacteria (E. coli), 

and constituents relating to their sources or transport 

(discharge, suspended solids) or their effects on water 

quality (biochemical oxygen demand, DO) were 

collected. Samples also were collected for analysis of 

trace elements and other inorganic constituents in water 

— data for those samples are stored in the CWS 

database but are not interpreted in this report. Multiple 

samples were collected at three sites during each storm, 

with the intent of characterizing conditions throughout 

individual storm hydrographs. Statistical relations 

among constituents are analyzed among all samplings, 

with exceptions unique to individual storms evaluated 

where they indicate important processes. Patterns and 

linkages from upstream to downstream also are 

explored. 

Description of Study Area

Fanno Creek is one of several major tributaries to 

the Tualatin River and is classified as 100 percent 

urban (fig. 1). It originates within the Portland city 

limits and flows 15 miles through parts of the 

neighboring suburbs of Beaverton, Tigard, and Durham 

before emptying into the Tualatin River at river mile 

9.3. The 32 square-mile Fanno Creek drainage basin 

includes a number of smaller tributaries such as Sylvan, 

Vermont, Ash, Summer, and Ball Creeks. 

Approximately 69 percent of the urban area is 

composed of residential communities, 21 percent is 

classified as industrial and commercial, and the 

remaining 10 percent is open space (including public 

parks and schools). Approximately 33 percent of the 

area is considered impervious, two-thirds of which 

contains storm drains that empty directly into a stream. 

The soils generally are highly consolidated silts and 

clays, and infiltration rates are relatively low, with 

moderately high soil phosphorus availability 

(Kurahashi and Associates, Inc., 1997). There are 27 

direct and indirect National Pollutant Discharge 

Elimination System (NPDES) permittees along the 

stream, several of which are temporary for the duration 

of short term projects such as construction (Oregon 

Department of Environmental Quality, 2002). Fanno 

Creek’s streamflow is typical of an urban stream in the 

Pacific Northwest, with flashy and relatively high flow 

during winter rainfall periods and low flows dominated 

by ground-water discharge during the dry summer 

(McCarthy, 2000). 

Acknowledgments

This project was funded in partnership with 

Clean Water Services (CWS). Jan Wilson and Jan 

Miller of CWS provided the impetus and direction for 

investigating Fanno Creek, and provided the laboratory 

analyses. Special thanks to Korin Henderson and others 

at the CWS laboratory for setting up and processing E. 

coli analyses at night and on weekends to meet sample 

holding-time requirements. Within the U.S. Geological 

Survey, Micelis ‘Clyde’ Doyle provided major 

logistical and field assistance. Other sampling help 

came from Matt Johnston, Kurt Carpenter, Amy 

Brooks, Doug Lee, and Tirian Mink. Roy Wellman 

measured streamflow at Scholls Ferry Road near Allen 

Boulevard and developed a stage-discharge rating 

curve for that site. 
4 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99

EXPLANATION

BOUNDARY OF FANNO CREEK DRAINAGE BASIN

SAMPLING SITE AND NO. — Site name is shown

 in table 1

Rock

Creek

Butternut Cre ek

McFee Creek

Beaverton

Creek

Bronson

Creek

Nyberg Cr.

Heaton

Creek

Cedar

Mill

Creek

TUALATIN

RIVER

Chicken Cr.

Summer Creek

Ball Cre ek

Ash

Creek

Fanno

Creek

Sylvan

Cr.

Pendleton Cr.

Vermont

Creek

Fanno

Cr.

WILLAMETTE RIVER

Lake Oswego

Tigard

Farmington

Scholls

Beaverton

Tualatin

26

26

T U A L A T I N

M O U N T A I N S

5

5 F2

F3

F1

F1

Durham

Portland

O R E G O N

Figure

location

Tualatin

Basin

122 ̊ 57'30'' 122 ̊45'

45 ̊

22'

30''

45 ̊ 

30'

0 1 2 3 4 MILES 

0 1 2 3 4 KILOMETERS

Base modified from U.S. Geological Survey

1:100,000, topographic quadrangle, 1978-84

Figure 1. Location of study area and storm sampling sites, Fanno Creek, Oregon.
Methods and Quality Assurance 5

METHODS AND QUALITY ASSURANCE

Samples were collected at three sites (table 1) 

during storms occurring in the summer, winter, and 

fall. Typically, 8 to 10 water-quality samples were 

collected from each site during each storm, including 

samples near the beginning and ending of the storm. 

Samples were intended to represent the initial 

conditions, rising limb, peak discharge, falling limb, 

and the tail of hydrographs at each site, with additional 

samples to fill data gaps (see fig. 2 for an example). 

Discharge and Water Quality

Discharge at the 56th Avenue site was measured 

and continuously gaged according to standard USGS 

techniques (Rantz and others, 1982a). Discharge data 

for Fanno Creek at Durham Road were provided by the 

Oregon Water Resources Department (OWRD). 

Discharge at Scholls Ferry Road near Allen Boulevard 

(herein referred to as Allen Boulevard) was not gaged 

continuously, but was estimated (Rantz and others, 

1982a) from a rating curve developed by USGS using 

periodic streamflow measurements and stage readings 

from a staff plate. Precipitation was measured at 

several sites in the subbasin by USGS and the City of 

Portland using standard tipping bucket gages; data 

presented in this report are from a raingage at the 

Vermont Hills Pump Station (City of Portland, 2002).

Field parameters (water temperature, dissolved 

oxygen, pH, and specific conductance) were measured 

inplace using HydrolabTM multiparameter probes, 

calibrated in the field according to manufacturer’s 

recommendations and standard USGS protocols (Wilde 

and Radtke, 1998). Water samples were collected along 

a cross section (minimum 3 verticals) using a weighted 

bottle sampler suspended from a bridge, and 

composited into a churn splitter. Subsamples were 

drawn from the churn splitter, processed immediately 

using standard protocols, and stored on ice for no more 

than 6 hours, until they could be transferred to the 

laboratory at CWS for analysis. Analysis of bacteria 

samples by CWS was started immediately upon 

receipt, and analysis of water samples was typically 

completed within 1-3 days for all other constituents 

except measurements of 5-day and ultimate 

biochemical oxygen demands (BOD5, BODult). 

Measurements of BOD5 and BODult, which were made 

locally by USGS personnel, required up to 30 days for 

completion. 

Water samples were analyzed by CWS for 

several measurements of suspended solids, oxygen 

demand, nutrients, and bacteria (table 2) using methods 

previously described (Doyle and Caldwell, 1996). 

Initially, subsamples for suspended solids, BOD, total 

nutrients, and bacteria were drawn from the churn 

splitter, following which subsamples for dissolved 

nutrients were taken. Subsamples for bacteria were 

drawn directly into certified-sterile plastic bottles; 

subsamples for BOD were drawn into standard 300-mL 

glass BOD bottles. Filtration in the field for dissolved 

nutrients was accomplished by passing water from 

syringes through 22-mm diameter, 0.45 μm pore-size, 

cellulose-nitrate disc filters. Subsamples for nutrients 

were unpreserved, with the exception of samples 

provided to the Oregon Department of Environmental 

Quality (ODEQ) for an interlaboratory split. ODEQ 

samples were processed and preserved as described by 

the Oregon Department of Environmental Quality 

(1994b).

)

Table 1. Storm sampling sites in Fanno Creek, Oregon, 1998–99

[Latitude and Longitude are given in degrees, minutes, and seconds. Abbreviations: USGS, U.S. Geological Survey; CWS, Clean Water Services. 

mi2, square miles]

Site name Map No.

(fig. 1)

USGS

site ID

CWS

site ID Latitude Longitude Rivermile

Drainage

area 

(mi2)

Fanno Creek at Durham Road F1 14206950 3840012 45N 24 13 122W 45 13 1.2 31.5

Fanno Creek at Scholls Ferry 

Road near Allen Boulevard

F2 14206925 3840095 45N 28 16 122W 46 25 9.5 12.0

Fanno Creek at 56th Avenue F3 14206900 3840126 45N 29 17 122W 44 01 12.6 2.37
6 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99

23 24 25

0.1

1

10

100

1,000

0.1

1

10

100

1,000

13 14 15 16 17 18 19 20

DISCHARGE, IN CUBIC FEET PER SECOND

5 6

DECEMBER 1999

7 8

0

0.2

0.4

0.6

0.8

0

0.1

0.2

0.3

0.4

0.5

HOURLY PRECIPITATION, IN INCHES

0

0.1

0.2

0.3

Storm 1—June 1998

Storm 2—January 1999

Storm 3—December 1999

0.1

1

10

100

1,000

JANUARY 1999

JUNE 1998

DISCHARGE

SAMPLING POINT

PRECIPITATION

56th Avenue

Durham Road

Figure 2. Discharge, precipitation, and sampling times at 56th Avenue (14206900) and at Durham Road (14206950) during 

three storms, Fanno Creek, Oregon, June 1998 to December 1999.

Discharge at the Allen Boulevard site (14206925) was not gaged continuously, so hydrographs from that site are not shown in 

this or other figures. Precipitation was recorded at the Vermont Hills Pump Station near the 56th Avenue sampling site. 
Results 7

Quality Assurance Results

The Quality Assurance (QA) program and 

results for this study are given in Appendix A (at back 

of report). In general, the QA program indicated few 

limitations for the data in this report because variability 

associated with changing flow conditions was typically 

much greater than variability associated with field and 

laboratory procedures, and no large biases were 

evident. On the basis of split sample results, the largest 

source of variability and bias appears to have been the 

laboratory used for analysis (see Appendix A). For this 

study, all environmental samples were processed at the 

CWS laboratory so the dataset is internally consistent. 

No major concerns were otherwise noted for that 

laboratory, so the data are considered acceptable. 

Results of quality control tests are provided in table A1

and are discussed in greater detail in the appendix.

RESULTS

Storms Sampled

One storm each was sampled during summer, 

fall, and winter from 1998 to 1999 (figs. 2 and 3 and 

table 3). The magnitude of discharge during these 

storms was variable, in keeping with the flashy nature 

of urban streams, but represented a typical range of 

flows during the study period. The biggest storm 

sampled was storm 2, in January 1999, with a peak 

storm discharge of 800 ft3/s at Durham Road, 

representing the third highest peak flow during the 

study period. Peak discharge during storm 3 was low 

(maximum 262 ft3/s) compared to that during storm 2 

but it was representative of fall storms during 1999 up 

to that date. Peak discharge during storm 1 (maximum 

152 ft3/s) was the lowest sampled but was nonetheless 

typical of spring and summer storms during 1998–99.

Table 2. Constituents analyzed from water samples collected during stormflows in Fanno Creek, Oregon, 1998–99

[Analyzing Laboratory: CWS, Clean Water Service, USGS, U.S. Geological Survey. Abbreviations: mg/L, milligrams 

per liter; mL, milliliters; NTU, nephelometric turbidity units]

Parameter (abbreviation) STORET 

code Unit Reporting level

Analyzing 

laboratory

Total solids (TS) 500 mg/L 2 CWS

Total Suspended Solids (TSS) 530 mg/L 0.2 CWS

Total Volatile Suspended Solids (TVSS)1 535 mg/L .2 CWS

Total Dissolved Solids (TDS)2 515 mg/L 2 CWS

Turbidity 76 NTU .1 CWS

Biochemical oxygen demand, rate (BODrate) — day-1 .01 USGS

Biochemical oxygen demand, 5-day (BOD5) 310 mg/L .1 USGS

Biochemical oxygen demand, ultimate (BODult) 319 mg/L .1 USGS

Ammonia-nitrogen (NH3-N) 608 mg/L .01 CWS

Nitrate plus nitrite nitrogen (NO3+NO2-N) 631 mg/L .01 CWS

Total Phosphorus (TP) 665 mg/L .025 CWS

Soluble Reactive Phosphorus (SRP) 671 mg/L .005 CWS

E. coli bacteria 31648 (100 mL)-1 1 CWS

1TVSS is a component of TSS.

2Calculated as TS minus TSS.
8 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99 DISCHARGE, IN CUBIC FEET PER SECOND

0

500

1,000

1.500

1998 1999 2000

APR JULY OCT JAN APR APR JULY OCT JAN Storm 1 (summer) Storm 2 (winter) Storm 3 (fall)

Figure 3. Discharge and storms sampled at Durham Road (14206950), Fanno Creek, Oregon, April 1998 to April 2000.

Table 3. Storm dates and number of samples at each site in the Fanno Creek drainage basin, Oregon

[Peak storm discharge: Estimates of peak storm discharge are not available for Fanno Creek at Allen Boulevard because that site is 

ungaged. Approximate storm precipitation: Precipitation data are from a raingage at the City of Portland’s Vermont Hills Pumping 

Station, and include the overall rainfall during the sampling period. Abbreviations: ft3/s, cubic feet per second; in., inches]

Storm No. Date Sampling site Number of 

samples

Peak 

discharge 

sampled

(ft3/s)

Peak storm 

discharge 

(ft3/s)

Approximate 

storm 

precipitation 

(in.)

1

(summer)

June 23–25, 1998 56th Avenue 8 43 44

Allen Boulevard 9 85 — 2.3

Durham Road 8 145 152

2

(winter)

January 13–19, 1999 56th Avenue 10 76 277

Allen Boulevard 10 135 — 3.7

Durham Road 10 584 800

3

(fall)

December 5–8, 1999 56th Avenue 9 37 92

Allen Boulevard 9 82 — 1.5

Durham Road 8 261 262
Results 9

Hydrographs during individual sampling periods 

typically included several discharge peaks due to 

variations in precipitation patterns (fig. 2), with 8 to 10 

samples collected at each site during each storm. 

Discharge in Fanno Creek at 56th Avenue was the 

flashiest, often with several peaks for every one at 

Durham Road. Downstream attenuation of discharge 

into broad peaks was pronounced at Durham, even 

though the magnitude of discharge was usually greater 

due to the additional contributing drainage basin area. 

Nonetheless, peak discharge at 56th Avenue was 

occasionally almost as high as that eventually 

measured at Durham, and in one case (during a new 

storm after sampling had ended during June 1998) was 

higher because of the flashiness at 56th Avenue (fig. 2). 

Discharges and attenuation of hydrographs at the 

midbasin site, Allen Boulevard, were intermediate to 

those at 56th Avenue and Durham Road. Because of 

this pattern, samples collected at 56th Avenue typically 

did not represent just one cycle of rising and falling 

discharge but rather a series of fluctuations in 

discharge. In contrast, at Durham there was usually a 

steadily increasing hydrograph during the sampling 

period, albeit with some minor fluctuations. The 

exception was storm 1, which was a single, discreet 

rainfall event and had just one discharge peak at all 

locations during the sampling period. 

Water Quality

A simple spearman’s correlation matrix (table 4) 

of all data (Appendix B) indicates that several 

constituents were correlated with many other 

constituents, whereas others were correlated with few 

to no other constituents. These results are evaluated in 

more detail in the following sections to help develop 

hypotheses regarding the sources of various 

constituents and their mechanisms of transport. Data 

also are examined for upstream-downstream processes 

or linkages, and for variability within and among 

storms that may indicate different sources or processes. 

Water-quality data from each storm are given in 

Appendix B. 

Discharge

Discharge was significantly correlated 

(p<0.0001) with TS, TVSS, TSS, turbidity, and TP, and 

all correlations were positive. However, all 

combinations had correlation coefficients (Spearman’s 

rho, or ρ) between 0.5 and 0.7, indicating that similar 

processes may have controlled the effect of discharge 

on each of these parameters. All are measures of, or are 

commonly associated with, particulates in water. None 

of the dissolved constituents (for example, NO3-N, 

NH3-N, SRP, TDS) were significantly correlated with 

discharge. Interestingly, bacterial concentrations also 

were not significantly correlated with discharge, even 

though bacteria are commonly associated with 

particulates (Schillinger and Gannon, 1985). However, 

stream energetics dictate that the ability of streamflow 

to suspend particulate material is typically greater on 

the rising limb of a discharge hydrograph than on the 

falling limb (Leopold, and others, 1995). Therefore, 

such correlations with discharge are not likely to be 

clear or consistent without more data over a greater 

range of discharges.

Solids

Of the five measurements of solids in water, TS, 

TVSS, TSS, and turbidity were significantly correlated 

with discharge, but TDS was not (table 4). TS was 

significant and strongly correlated with TVSS, 

turbidity, and TSS (fig. 4), but all four were weakly and 

negatively correlated with TDS. These findings are 

reasonable, because TS incorporates TSS (and thereby 

TVSS), representing particulates brought in or 

resuspended during storms, whereas TDS typically is 

reduced at higher flows due to dilution (Hem, 1989). 

Although the correlation coefficients for TSS and 

TVSS with TS were equivalent (0.82 and 0.84, 

respectively), the slope of the line was much steeper for 

the relation between TS and TSS (fig. 4). In terms of a 

surrogate measurement, TSS is much more 

representative of total solids in transport in the Fanno 

Creek drainage basin than is TVSS. Nonetheless, 

TVSS may be of interest if the component of 

particulates that is composed of biological or 

decomposable materials is a large fraction of the TS 

load. TVSS might be expected to undergo significant 

seasonal variation if the source area includes suitable 

habitat for algal growth (SoloGabriele and Perkins, 

1997). Other potential sources for TVSS include 

leaves, riparian vegetation, and detritus.
10 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99 Table 4. Correlations for selected water-quality constituents during storm conditions in Fanno Creek, Oregon, 1998–99 [Within a table cell, the upper row shows Spearman’s correlation coefficient (rho or ρ), the middle row shows probability (p) that the null hypothesis of no correlation is true, and the lower row shows number of samples (n). Numbers in bold indicate correlations that are significant at p<0.01] Discharge TS TDS TVSS TSS Turbidity BODrate BOD5 BODult TP NH3-N NO3-N SRP

E. coli

Discharge

1

—80

TS 

0.6387 1

<0.0001

—

80 81

TDS

-0.2553 -0.0283 1

0.0232 0.8032

—

79 80 80

TVSS

0.6482 0.8221 -0.4832 1

<0.0001 <0.0001 <0.0001

—

81 81 80 81

TSS

0.7022 0.8441 -0.4635 0.9885 1

<0.0001 <0.0001 <0.0001 <0.0001

—

80 81 80 81 81

Turbidity

0.5544 0.7475 -0.4347 0.8720 0.8890 1

<0.0001 <0.0001 <0.0001 <0.0001 <0.0001

—

80 81 80 81 81 81

BODrate

0.0507 0.0231 -0.1104 0.1134 0.0732 -0.0638 10.7218 0.8682 0.4314 0.4143 0.5988 0.6467

—

53 54 53 54 54 54 54

BOD5

0.2798 0.4100 -0.5516 0.6801 0.6325 0.4495 0.5680 10.0425 0.0021 <0.0001 <0.0001 <0.0001 0.0006 <0.0001

—

53 54 53 54 54 54 54 54

BODult

0.4067 0.5074 -0.6659 0.8074 0.7734 0.6280 0.1730 0.8781 10.0025 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 0.2108 <0.0001

—

53 54 53 54 54 54 54 54 54

TP

0.5703 0.7422 -0.4986 0.9105 0.9120 0.8785 0.0224 0.5174 0.6817 1

<0.0001 <0.0001 <0.0001 <0.0001 <0.0001 <0.0001 0.8725 <0.0001 <0.0001

—

80 81 80 81 81 81 54 54 54 81

NH3-N

0.1606 0.4161 -0.0557 0.4870 0.4383 0.3233 0.2882 0.2421 0.1358 0.4049 10.1548 0.0001 0.6235 <0.0001 <0.0001 0.0032 0.0346 0.0777 0.3276 0.0002

—

80 81 80 81 81 81 54 54 54 81 81

NO3-N

-0.1548 -0.0560 0.6083 -0.3248 -0.2900 -0.1001 0.0444 -0.5057 -0.6401 -0.3904 -0.0829 1

0.1703 0.6197 <0.0001 0.0031 0.0086 0.3739 0.7499 <0.0001 <0.0001 0.0003 0.4622

—

80 81 80 81 81 81 54 54 54 81 81 81

SRP

0.1208 -0.1074 -0.3342 0.0458 0.0546 -0.0117 -0.0337 0.0415 0.0594 0.2252 -0.1670 -0.4324 10.2858 0.3398 0.0024 0.685 0.6284 0.9175 0.8089 0.7658 0.6695 0.0432 0.1361 <0.0001

—

80 81 80 81 81 81 54 54 54 81 81 81 81

E. coli

-0.0271 0.1130 -0.6398 0.4516 0.4197 0.4070 -0.0789 0.4583 0.6225 0.6022 0.1763 -0.6134 0.4739 1

0.8117 0.3152 <0.0001 <0.0001 <0.0001 0.0002 0.5708 0.0005 <0.0001 <0.0001 0.1153 <0.0001 <0.0001

—

80 81 80 81 81 81 54 54 54 81 81 81 81 81
Results 11

Clearly, solids concentrations are dependent on 

discharge and changes in discharge; however, these 

correlations indicate that discharge only accounted for 

about 35 to 50 percent of variation (taken as the square 

of the correlation coefficient, rho) in the concentrations 

of TS, TSS, and TVSS. It is well established that 

sediment concentration during stormflow in most 

streams tends to peak prior to the discharge peak 

(Leopold and others 1995), as was observed in Fanno 

Creek during this study (fig. 5). Portraying the 

chronological sequence of sediment concentrations as a 

function of discharge therefore can result in a loop 

(Dunne and Leopold, 1978) illustrating that for a given 

storm and discharge, sediment concentrations may be 

different on the rising and falling limbs of the 

hydrograph. During storm 1 in Fanno Creek, the only 

storm for which one distinct hydrograph was sampled, 

a clockwise loop was observed in TSS concentrations 

(fig. 6). This pattern suggests that sediment delivery 

was limited by available supplies (Richards, 1982; 

Ferguson, 1987; Knighton, 1998), and that therefore 

the sediment was more likely from nearby sources, 

such as previously deposited materials within the 

streambed, bank erosion, immediate channel margins, 

or small tributaries, than from more distant upland 

sources and transported to the stream by overland

runoff (Richards, 1982). However, many of the 

observations in the literature were developed for 

unimpacted streams, and it is unclear whether a similar 

pattern in urban streams, with their distinctive 

hydrologic and morphological characteristics (flashy 

hydrographs, limited channel change due to 

reinforcements, upland impervious surfaces, and 

construction) can be interpreted in the same manner. 

100

150

200

250

300

350

400

TOTAL SOLIDS CONCENTRATION, 

IN MILLIGRAMS PER LITER

0

50

100

150

200

DISCHARGE, IN CUBIC FEET PER SECOND

23 24 25

JUNE 1998

DISCHARGE

TOTAL SOLIDS CONCENTRATION

Figure 5. Discharge and total solids concentrations at Durham Road 

(14206900) during storm 1, Fanno Creek, Oregon, June 23-25, 1998. 

0 400 800 1,200

0

200

400

600

800

1,000

TOTAL SUSPENDED SOLIDS (slope = 1.04)

TOTAL VOLATILE SUSPENDED SOLIDS (slope = 0.11)

TOTAL DISSOLVED SOLIDS (slope = – 0.32)

0

0.5

1.0

1.5

2.0

2.5

3.0

TOTAL PHOSPHORUS (slope = 0.0019)

SOLIDS CONCENTRATION, IN MILLIGRAMS PER LITER

TOTAL SOLIDS, IN MILLIGRAMS PER LITER

TOTAL PHOSPHORUS CONCENTRATION, IN MILLIGRAMS PER LITER

Figure 4. Correlation of total solids (TS) with total suspended solids (TSS), total volatile suspended solids (TVSS), total dissolved 

solids (TDS), and total phosphorus (TP) at all sampling sites during three storms, Fanno Creek, June 1998 to December 1999.
12 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99

Techniques such as baseflow separation and 

semi-empirical models for characterizing the properties 

of sediment-discharge loops have been used elsewhere 

to evaluate the relative importance of point and 

nonpoint sources in stream basins (House and 

Warwick, 1998; SoloGabriele and Perkins, 1997). For 

this report, data are not available to conclusively 

ascribe different parts of the sediment or solute 

hydrographs to different processes or sources within 

the basin. However, it is reasonable to conclude that 

much of the sediment in transport in Fanno Creek was 

existing streambed material that was simply 

resuspended during increases in streamflow. If that 

conclusion is correct, it follows that multiple storms, if 

they are of similar magnitude as storm 1, would be 

required to transport sediment from the upstream 

reaches throughout the entire length of Fanno Creek 

and into the Tualatin River. Alternatively, existing 

storm drains that discharge to the creek could cause a 

short circuiting of normal sediment delivery routes, 

bringing sediment from upland sources to the stream 

faster than would otherwise occur. This process could 

confound the interpretation of data from this study and 

must be considered as an alternate explanation for the 

higher sediment concentrations on the rising limbs of 

hydrographs, particularly at the downstream sites 

(Allen Boulevard and Durham Road). 

Although peak suspended-solids concentrations 

during storm 1 were highest at 56th Avenue, as 

illustrated by discharge-sediment concentration loops 

(fig. 6A), peak loads were similar at the three sites 

(fig. 6B). Furthermore, the cumulative amount of 

material transported was much greater at the Durham 

site owing to the higher discharges there and the larger 

contributing area (fig. 7A). Nonetheless, when 

normalized for the contributing area (that is, divided by 

the area of the upstream drainage basin), the yield of 

TS at 56th Avenue was much greater than the yield at 

Durham Road (fig. 7B). This may reflect a combination 

of the higher gradient near 56th Avenue, which results 

in higher velocities and energy to suspend particles, 

and differences in impervious surface area, riparian 

conditions, temporary construction activities, or other 

dynamic factors in urban environments. Additionally, 

several large ponds and some slow moving reaches 

between 56th Avenue and the Durham site provide 

opportunities for deposition of suspended material 

transported from upstream.

INSTANTANEOUS TOTAL SOLIDS CONCENTRATION,

IN MILLIGRAMS PER LITER 400

200

0

600

800

1,000

INSTANTANEOUS TOTAL SOLIDS LOAD,

IN KILOGRAMS PER HOUR 2,000

1,000

0

3,000

4,000

5,000

DISCHARGE, IN CUBIC FEET PER SECOND

0 50 100 150 200 0 50 100 150 200

DISCHARGE, IN CUBIC FEET PER SECOND

ALLEN BOULEVARD

CHRONOLOGICAL SEQUENCE

OF SAMPLING

56th AVENUE

DURHAM ROAD

A B

Figure 6. Relation of instantaneous concentrations and loads with discharge at all sampling sites during storm 1, Fanno Creek, Oregon, June 23-25, 1998.

Arrows indicate the chronological sequence of sampling, with the loops illustrating that a given discharge can produce different sediment concentrations or 

loads depending on the stage of the hydrograph.
Results 13

Sampling during storms 2 and 3 was conducted 

over fluctuating flows that were less indicative of an 

individual storm hydrograph than of common flow 

conditions during fall and winter in Pacific maritime 

urban communities (fig. 2). With these kinds of 

variations in streamflow, solids concentrations also 

were highly variable (fig. 8). Consequently, no 

particular pattern is discernible other than the general 

correlations indicated in table 4. TS concentrations did 

not increase significantly between 56th Avenue and 

Durham Road, despite the increase in loads, possibly 

due to the higher channel gradient at 56th Avenue and 

deposition sites, including ponds and wetlands, 

downstream. 

CUMULATIVE SOLIDS LOADS, IN KILOGRAMS 30,000

20,000

10,000

0

40,000

50,000

60,000

CUMULATIVE SOLIDS YIELD, 

IN KILOGRAMS PER SQUARE MILE 2,000

1,000

0

3,000

4,000

5,000

JUNE 1998

23 25 24

JUNE 1998

23 25 24

56th AVENUE

DURHAM ROAD

A B

Figure 7. Cumulative loads and yields at 56th Avenue (upstream site; 14206900) and at Durham Road (downstream site; 

14206950) during storm 1, Fanno Creek, Oregon, June 23–25, 1998.

[Cumulative loads and yields were calculated by simple indexing of concentrations at midpoints between times of samplings 

and multiplying by cumulative discharge obtained from 15 minute readings.] 

1

10

100

1,000

1

10

100

1,000

5678

DISCHARGE, IN CUBIC FEET PER SECOND

TOTAL SOLIDS CONCENTRATION, 

MILLIGRAMS PER LITER

0

50

100

150

200

0

50

100

150

200

DECEMBER 1999

DISCHARGE

TOTAL SOLIDS 56th Avenue

Durham Road

Figure 8. Discharge and total solids (TS) concentrations at 56th Avenue (14206900) and at Durham Road 

(14206950) during storm 3, Fanno Creek, Oregon, December 5-8, 1999.
14 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99

Biochemical Oxygen Demand

Both BOD5 and BODult were significantly 

correlated (p<0.01 – p<0.0001) with concentrations of 

solids (TS, TDS, TSS, TVSS, turbidity), some nutrients 

(TP and NO3-N), and bacteria, although the BODrate, 

which is the first-order BOD loss rate and commonly is 

used in modeling, was correlated only with BOD5

(table 4). Nonetheless, most correlations were 

relatively weak, the strongest correlation coefficients 

being 0.81 and 0.77 for BODult with TVSS and TSS, 

respectively. These associations are reasonable, 

because TVSS represents much of the material that 

decomposes to create BOD, and support the use of 

TVSS as a surrogate for BOD in TMDL 

considerations. Correlations of BOD with TDS and 

NO3-N were negative, reinforcing the hypothesis that 

most of the BOD during storms is due to decomposable 

particulate material. Interestingly, the different 

measures of BOD were correlated only poorly with 

discharge (for BOD5, p <0.05), which is likely an 

outcome of variability associated with the differences 

in solids concentration over the discharge hydrograph 

(figs. 5 and 6).

Bacteria

The State of Oregon, following guidelines from 

the U.S. Environmental Protection Agency (USEPA) 

has set a standard of no more than 406 E. coli colonies 

per 100 mL in a single sample of stream water (Oregon 

Department of Environmental Quality, 2001a). 

Bacterial counts exceeded the single sample standard in 

most of the samples taken during this study, including 

each sample from storm 1. Overall, E. coli counts were 

higher during storm 1 than during any other storm 

(fig. 9), most likely as a result of lower stormflows and

100

1,000

STORM 1

JUNE 1998

SUMMER

Oregon single sample criterion

STORM 2

JANUARY 1999

WINTER

STORM 3

DECEMBER 1999

FALL

10,000

100,000 BACTERIA CONCENTRATION, IN COLONIES PER 100 MILLILITERS

1.5 × INTERQUARTILE RANGE

OUTLIER

75th PERCENTILE

50th PERCENTILE – MEDIAN

25th PERCENTILE

1.5 × INTERQUARTILE RANGE 56th AVENUE ALLEN BOULEVARD DURHAM ROAD

EXPLANATION

Figure 9. E.coli bacteria concentrations at each sampling site during three storms, Fanno Creek, Oregon, June 

1998 to December 1999. 

Dashed line shows the State of Oregon E. coli single-sample criterion. Allowable cumulative concentrations 

from point sources in storm runoff are 5,000 colonies/100 mL during winter and 12,000 colonies/100 mL during 

summer, as defined by a Total Maximum Daily Load (TMDL) for the Tualatin River Basin (Oregon Department of 

Environmental Quality, 2001b).
Results 15

warmer water temperatures in the days and weeks 

preceding and during that storm (median 15.2 oC) than 

during storms 2 and 3 (medians 8.2 and 8.4 oC, 

respectively). E. coli counts (50 to 90 percentiles) also 

were higher at 56th Avenue than at either of the 

downstream sites during storm 1 and to a lesser extent 

(medians only) during storms 2 and 3. Bacteria were 

weakly associated with TSS and turbidity (ρ ≈ 0.41 for 

both — see table 4), so the relatively high solids 

concentrations at 56th Avenue compared to the 

downstream sites, particularly during storm 1, may 

partially explain the higher bacteria counts at that site. 

Bacteria in streams are commonly associated with 

suspended particles (Schillinger and Gannon, 1985; 

Hunter and others, 1999), either because they were 

transported to the streams attached to the particles, they 

were bound to streambed sediment (Matson and others, 

1978) that has been resuspended (Grimes, 1975; 

Matson and others, 1978; Hunter and others, 1999) or 

because of specific bacterial affinities for sediment 

particles (Scholl and Harvey, 1992; Mills and others, 

1994; Bolster and others, 2001) that may occur in the 

water column.

E. coli counts were weakly correlated with TSS, 

turbidity, BOD5 and BODult, TP, and SRP, and were 

not correlated with discharge or TS. Negative 

correlations with E. coli were found for TDS and NO3-

N, reinforcing the positive association between E. coli

and particulate material. Although bacterial transport 

has been correlated with stream stage (Hunter and 

others, 1992) and discharge (Davis and others, 1977) 

during storms and also tends to be associated with the 

transport of suspended sediment (Davis and others, 

1977), these associations are not always evident 

(Qureshi and Dutka, 1979). In Fanno Creek, the lack of 

correlations may indicate that contributing sources or 

processes for bacteria were different from storm to 

storm. In an analysis of microbiological data from a 

national database, Francy and others (2000) also found 

E. coli concentrations, at a mixture of urban and 

agricultural sites, to be uncorrelated with discharge (or 

temperature), though they were correlated with 

concentrations of suspended sediment, TP, and NO3-N. 

Bacterial sources

Potential sources of bacteria to streams are 

numerous. Reports from several studies (Young and 

Thackston, 1977; Hunter and others, 1992, 1999) have 

indicated that upland soils are able to maintain a pool 

of bacteria and other pathogens that are transported to 

streams during runoff, often with higher concentrations 

during summer (Hunter and others, 1999). Other 

upland sources have included sewage outfalls (Matson 

and others, 1978; Jacobs and Ellis, 1991), septic 

systems (Young and Thackston, 1977), and wastes 

from birds, dogs (Young and Thackston, 1977), and 

other animals. In urban sections of the Boise River, 

Idaho, principle bacterial sources (identified 

semiquantitatively by analysis of bacterial DNA) 

included birds (about 30 percent), pets (about 22 

percent), and humans (about 17 percent) (CH2MHill, 

2002). However, in that case the study reaches 

contained sewage outfalls, whereas Fanno Creek 

contains storm drains but not sewage outfalls. Thus, the 

relative contribution of human sources to indicator 

bacteria in Fanno Creek may be less than in the Boise 

River. McCarthy (2000) suggested that domestic pets, 

birds, and improperly managed wildlife may have been 

important sources of E. coli to various Tualatin River 

tributaries, including Fanno Creek, during summer 

low-flow conditions. 

Qureshi and Dutka (1979) found that groundwater seepage into storm drains in urban areas, even 

during non-runoff periods, contained sufficiently large 

quantities of bacteria to confound correlations with 

streamflow. Other studies have implicated streambed 

sediment and its resuspension (Grimes, 1975; Matson 

and others, 1978), and suspended sediment in general 

(Davis and others, 1977; Schillinger and Gannon, 

1985; Francy and others, 2000; Embrey, 2001), as 

sources and principal transport vectors for bacteria. 

In this study, data are not available to 

conclusively determine specific sources of bacteria 

during storms in Fanno Creek. Correlations of E. coli

with TSS, TVSS, turbidity, and TP indicate 

associations with particulate material, but it is unclear 

if that particulate material resulted from soils 

transported to the stream from upland sources or from 

erosion and resuspension of sediment already in the 

streambed. To the extent that clockwise sedimentdischarge loops, as observed in this study, suggest a 

limit to the available sediment supply during storms, 

bacteria associated with particulates may have 

primarily come from resuspension of streambed 

sediment (Grimes, 1975; Matson and others, 1978). 

However, there also is an indication that some 

particulates sampled at 56th Avenue may have 

originated in upland areas, on the basis of higher 

concentrations (fig. 6A) and yield (fig. 7B) at that site, 
16 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99

so it is possible that bacteria associated with those 

particulates also may have come from upland sources. 

Nonetheless, these associations cannot be fully 

determined without additional data collection designed 

to answer specific questions about bacterial sources. 

E. coli in streams are considered indicators of 

waste contamination by warm-blooded animals 

(Embrey, 2001). Aside from the suggestion that the 

area upstream from 56th Avenue may have been the 

largest contributor of E. coli to Fanno Creek, data from 

this study are insufficient to determine geographic 

sources of bacteria or the types of animals from which 

the bacteria originated. Future studies to identify 

possible sources and organisms for fecal indicator 

bacteria might benefit from the emerging field of 

Bacterial Source Tracking (BST) (Field and Bernhard, 

2001; Hagedorn, no date); which uses molecular 

techniques to match genetic material of the sampled 

bacteria with known, species-specific “fingerprints” of 

different organisms. Use of these techniques might help 

to determine, for instance, whether the main bacterial 

source is avian, canine, human, or other species. 

Phosphorus

At the time of this investigation, the Total 

Maximum Daily Load in effect for the Tualatin River 

Basin, including tributaries, required that surface-water 

concentrations of TP remain less than or equal to 0.07 

mg/L as a monthly median during the period from May 

1 through October 31 (Oregon Department of 

Environmental Quality, 1994a). The subsequent 

revision of the TMDL (Oregon Department of 

Environmental Quality, 2001b) sets a median 

summertime TP concentration criterion of 0.13 mg/L in 

Fanno Creek; during other times of the year TP is not 

regulated. During this study, TP concentrations in 

samples from Fanno Creek equaled or exceeded 0.07 

mg /L of P in all but one sample from storm 3 

(December 1999) at Durham Road (fig. 10).

0.01

0.1

STORM 1

JUNE 1998

SUMMER

STORM 2

JANUARY 1999

WINTER

STORM 3

DECEMBER 1999

FALL

1.0

10.0 TOTAL PHOSPHPRUS CONCENTRATION, MILLIGRAMS PER LITER

1.5 × INTERQUARTILE RANGE

OUTLIER

75th PERCENTILE

50th PERCENTILE – MEDIAN

25th PERCENTILE

1.5 × INTERQUARTILE RANGE 56th AVENUE ALLEN BOULEVARD DURHAM ROAD

EXPLANATION

Oregon seasonal criterion

Total Maximum Daily Load 1998

Oregon seasonal criterion

Total Maximum Daily Load 2001

Figure 10. Total phosphorus (TP) concentrations at each sampling site during three storms, Fanno Creek, 

June 1998 to December 1999. 

Dashed lines indicate the median concentration allowed by the Total Maximum Daily Load (TMDL) in effect at 

the time of this study (1998–99) and the revised TMDL (2001), respectively.
Results 17

TP concentrations also exceeded the updated criterion 

concentration of 0.13 mg/L in more than 22 of the 24 

samples from storm 1. Concentrations were similar 

among sites, although variability tended to decrease in 

a downstream direction, a finding that is likely a result 

of the flashy nature of the upstream sites such as Fanno 

Creek at 56th Avenue. The highest overall 

concentrations of TP tended to occur at 56th Avenue, 

but many of the lowest concentrations were at that site 

as well. 

Concentrations of SRP were consistently much 

lower than those for TP, indicating that most of the 

phosphorus being transported was in the particulate 

phase. During all three storms, SRP was relatively 

stable, varying less than an order of magnitude, 

whereas discharge, TS, and TP fluctuated by larger 

amounts. Figure 11 illustrates this phenomenon during 

storm 1; similar patterns were observed during storms 2 

and 3. In fact, long-term data collected by CWS near 

the mouth of Fanno Creek (near the Durham Road site 

used in this study) indicate a robust seasonal pattern for 

SRP, with peak concentrations occurring in late 

summer, minimum concentrations in late winter and 

early spring, and overall variability that is substantially 

less than for TP (fig. 12). During low flows, SRP can 

constitute more than one-half of TP in the stream, 

whereas during stormflows in winter SRP can be only a 

small fraction of TP. In the current study, SRP was only 

poorly correlated with TP (p<0.05, table 4), was not 

correlated with discharge, TS, or TSS, and was 

negatively, but weakly, correlated (p<0.01) with TDS 

and nitrate concentrations. This pattern indicates that 

the sources for SRP are not strongly associated with 

those for TP or for particulates, nor were they strongly 

diluted by increased flow. Much of the SRP may 

instead have originated with a relatively constant 

shallow ground-water discharge, and higher flows 

during rainstorms may partly accelerate a flushing of 

local ground water into the streams. 

The consistently low SRP concentrations in the 

stream (median 0.046 mg/L) probably do not reflect 

direct phosphorus deposition in precipitation; limited 

available data indicate that phosphorus concentrations 

in precipitation in the Pacific Northwest are much 

lower than was observed in this study. For instance, in 

the Bull Run watershed, a pristine drinking water 

supply for the City of Portland in the Western Cascade 

Mountains, SRP in precipitation is typically less than 

0.01 mg/L (U.S. Geological Survey, 1983–93), and in 

the Andrews Experimental Forest near Eugene, 

Oregon, concentrations are typically about 0.006 to 

0.015 mg/L (Sollins and others, 1980; Martin and Harr, 

1988). Data are limited for SRP in precipitation in the 

Portland Metropolitan Area, but samples collected and 

analyzed at the USGS Oregon District Laboratory in 

November 2001 had SRP concentrations of 0.001 

mg/L. Thus, another source, such as ground water, is 

likely for the SRP measured in the stream.

The proportion of soluble P in the stream, 

calculated as the ratio of SRP:TP, was mostly in the 

range of about 5 to 45 percent during storms and was 

negatively correlated with the log of discharge (fig. 13); 

thus, at higher discharges, an increasing amount of the 

phosphorus in the stream was in particulate form. Yet, 

the amount of soluble phosphorus in transport, (load, in 

kilograms per day) continued to increase as the 

discharge increased, meaning that a larger mass of SRP 

was being discharged to the stream even if 

concentrations remained relatively unchanged. During 

summer low-flows, McCarthy (2000) found that the 

proportion of soluble phosphorus in Fanno Creek 

ranged from 30 to 50 percent, similar to that seen in 

this study. Maximum SRP concentrations in the 

summer, typically reaching about 0.1 mg/L at low flow, 

are indicative of the likely deep ground-water source in 

the basin (fig. 12). These findings also are consistent 

with the hypothesis that much of the SRP during fall 

and winter storms in Fanno Creek originated as ground 

water. Investigations of hydrologic flowpaths in Fanno 

Creek, including differentiating between deep and 

shallow ground-water inputs during storms, could be 

aided through the use of stable isotopes of oxygen 

(Buttle and others, 1995; Iqbal, 1998; Brown, and 

others, 1999), hydrogen (Turner and others, 1987; 

Kendall and others, 1995), and/or sulfur (Krouse and 

Mayer, 2000), or with ground-water dating techniques 

(Cook and Herczeg, 2000). 
18 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99

DISCHARGE

TOTAL PHOSPHORUS 

CONCENTRATION

SOLUBLE REACTIVE 

PHOSPHORUS CONCENTRATION

0

0.1

0.2

0.3

0.4

0.5

0.6

0

50

100

150

200

0

0.1

0.2

0.3

0.4

0.5

0.6

PHOSPHORUS CONCENTRATION, IN MILLIGRAMS PER LITER

0

50

100

150

200

DISCHARGE, IN CUBIC FEET PER SECOND

23 24 25

JUNE 1998

2.2 1.1

56th Avenue

Durham Road

Figure 11. Variability of total phosphorus (TP) and soluble reactive phosphorus (SRP) concentrations with 

discharge at 56th Avenue (14206900) and at Durham Road (14206950) during storm 1, Fanno Creek, Oregon, 

June 23-25, 1998.

Y-axis minimum for discharge at 56th Avenue is shifted below zero to allow low flow to be portrayed. 
Results 19

In contrast to soluble phosphorus, TP was 

significantly correlated (p<0.001), either positively or 

negatively, with most of the constituents analyzed 

except SRP (table 4). The relations between TP and 

various measures of particulates (TS, TVSS, TSS, and 

turbidity) were particularly strong, with Spearman’s 

rho (ρ) values ranging from 0.74 to 0.91, further 

indicating that sources of TP were largely particulate, 

either as erosion and overland runoff, bank erosion, or 

resuspension of bed materials. For example, the 

similarities between TS and TP are evident when 

comparing figures 5 and 11. Additionally, a clockwise 

looping pattern of TP concentrations with discharge 

during storm 1 (fig. 14) was very similar to the pattern 

of TS concentrations at the same sites (fig. 6), 

indicating concentration differences between the rising 

and falling limb of the storm hydrograph. TP was 

negatively correlated with TDS and NO3-N, suggesting 

dilution of those parameters as TP and other 

particulates increased during storms. 

0.1 1 100 1,000 10

DISCHARGE, IN CUBIC FEET PER SECOND

PERCENTAGE OF SOLUBLE PHOSPHORUS

20

0

60

80

40

100

Note: The line is for illustration of negative 

correlation only and does not imply a linear 

relationship over the entire range of 

possible data.

0

0.1

0.2

0.3

0.4

PHOSPHPORUS CONCENTRATION, IN MILLIGRAMS PER LITER

1991 1993 2000 2001 1992 1994 1995 1996 1997 1998 1999

SOLUBLE REACTIVE PHOSPHORUS

TOTAL PHOSPHORUS

TMDL PERIOD OF MAY 1 - OCTOBER 31

EXPLANATION

Figure 12. Seasonal patterns in monthly phosphorus concentrations in Fanno Creek, Oregon, 1991–2001.

Figure 13. Relation of soluble fraction of phosphorus with discharge 

at all sampling sites during three storms, Fanno Creek, Oregon, June 

1998 to December 1999.

Percentage of soluble phosphorus is calculated as 100* (SRP/TP). 
20 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99

Figure 14. Relation of total phosphorus (TP) concentrations with 

discharge at all sampling sites during storm 1, Fanno Creek, Oregon, June 

23-25, 1998.

Arrows indicate the chronological sequence of sampling, with the loops 

illustrating that a given discharge can produce different phosphorus 

concentrations depending on the stage of the hydrograph.

Nitrogen

Concentrations of NH3-N, which were mostly 

between 0.03 and 0.1 mg/L, were positively correlated 

with measures of particulates (TS, TVSS, TSS, 

turbidity) and TP, and negatively correlated with 

NO3-N. NH3-N is commonly associated with the 

decomposition of the organic fraction of particles in 

streams, such as leaf litter and other vegetative material 

from riparian and upland sources or algal and plant 

material from within the stream channel. The strongest 

correlation coefficient for NH3-N was with TVSS 

(rho=0.487), probably reflecting this association. The 

highest NH3-N concentrations, and most variable, 

occurred during the summer storm (storm 1), probably 

also reflecting accelerated decomposition of organic 

material. 

NO3-N concentrations were lowest during the 

summer storm in June 1998 (fig. 15), possibly 

reflecting nitrate consumption by upland plants, 

denitrification by microbial communities in the stream

TOTAL PHOSPHORUS CONCENTRATION,

IN MILLIGRAMS PER LITER 1.0

0.5

0

1.5

2.0

2.5

DISCHARGE, IN CUBIC FEET PER SECOND

0 50 100 150

ALLEN BOULEVARD

CHRONOLOGICAL SEQUENCE

OF SAMPLING

56th AVENUE

DURHAM ROAD

0

0.5

STORM 1

JUNE 1998

SUMMER

STORM 2

JANUARY 1999

WINTER

STORM 3

DECEMBER 1999

FALL

1.5

1.0

2.0

NITRATE-NITROGEN CONCENTRATION, IN COLONIES PER 100 MILLILITERS

1.5 × INTERQUARTILE RANGE

OUTLIER

75th PERCENTILE

50th PERCENTILE – MEDIAN

25th PERCENTILE

1.5 × INTERQUARTILE RANGE 56th AVENUE ALLEN BOULEVARD DURHAM ROAD

EXPLANATION

Figure 15. Nitrate nitrogen concentrations at each sampling site during three storms in Fanno Creek, Oregon, 

June 1998 to December 1999.
Results 21

margins, and/or uptake by algae and aquatic 

macrophytes in the stream. Concentrations during the 

fall and winter storms were higher than during the 

summer storm, with concentrations during the winter 

storm being the highest overall. This seasonal pattern 

in Fanno Creek, with low nitrate concentrations in the 

summer and high concentrations during winter runoff, 

is clearly evident when monthly monitoring data from 

many consecutive years are examined (fig. 16). 

Wintertime increases in streamwater NO3-N 

concentrations are common in Willamette Basin 

streams. Bonn and others (1996) demonstrated that 

median stream NO3-N concentrations peaked in 

December through February in the basin, and Rinella 

and Janet (1998) observed a similar pattern in both 

small and large streams in the valley. The source for 

this winter NO3-N may be shallow ground water, 

containing NO3-N resulting from fertilization, 

nitrification, and microbial mineralization of organic 

nitrogen. 

During all three storms in the current study, the 

lowest NO3-N concentrations tended to occur at the 

most downstream location, Durham Road, whereas the 

variability was the greatest at 56th Avenue, the most 

upstream location studied. Median concentrations 

during storms 2 and 3 were typically highest at Allen 

Boulevard. The reasons for decreased NO3-N 

concentrations at Durham Road are unknown but may 

by related to increased flow and therefore more dilution 

at that site. 

As a highly mobile ion that is often associated 

with ground water, NO3-N concentrations might be 

expected to increase with increasing stream discharge 

if ground water discharge increases during stormflow; 

however, such concentration increases with stream 

discharge are not evident in Fanno Creek. Overall, 

NO3-N was negatively correlated with TVSS, TSS, 

BOD5, BODult, TP, SRP, and E. coli bacteria (table 4), 

was positively correlated with TDS and DO (p<0.0001, 

rho=0.56, not shown in table 4), and was not correlated

0

0.5

1.0

1.5

2.0

NITRATE CONCENTRATION, IN MILLIGRAMS PER LITER

0

0.2

0.1

0.4

0.6

0.5

0.3

AMMONIA CONCENTRATION, IN MILLIGRAMS PER LITER

1991 1993 2000 2001 1992 1994 1995 1996 1997 1998 1999

EXPLANATION

AMMONIA NITROGEN

NITRATE NITROGEN

TMDL PERIOD OF MAY 1-OCTOBER 31

Figure 16. Seasonal patterns in monthly nitrate and ammonia nitrogen concentrations in Fanno Creek, Oregon, 1991–2001.
22 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99

with discharge. Although a simple correlation is not 

evident between NO3-N and discharge, there did 

appear to be a complex relation, whereby the direction 

of change in NO3-N was opposite the direction of 

change in flow (fig. 17). Thus, NO3-N was typically 

highest at a given site during lower flows, or just prior 

to an increase in flow, and concentrations decreased as 

flows increased. The lowest concentrations tended to 

occur just after the peak in discharge, with subsequent 

increases in concentrations as discharge continued to 

recede, probably reflecting dilution at the peak of the 

storm and subsequent flushing of shallow ground water 

between storm events.

The lack of a significant overall correlation 

between flow and NO3-N may simply have been due to 

the fact that, unlike storm 1, samples during storms 2 

and 3 were collected during varying flow conditions 

rather than over one discreet rise and fall sequence in 

stage. Additionally, NO3-N concentrations might be 

dependent on other factors, such as antecedent flow 

conditions, dilution by rainfall, and the character of 

inflowing ground water. The patterns observed during 

storm 1 suggest that dilution, or perhaps some other 

process, was important (fig. 17). Deep ground water in 

the Fanno Creek and larger Tualatin River basins is 

known to be reduced, with relatively high levels of 

NH3-N, low DO, and low NO3-N (Kelly and others, 

1999). 

Storm 1 — June 1998

Storm 3—December 1999

Storm 2—January 1999

179

277

NITRATE CONCENTRATION, MILLIGRAMS PER LITER

0

0.5

1.0

2.0

1.5

0

0.5

1.0

2.0

1.5

0

0.5

1.0

2.0

1.5

100

50

0

150

100

50

0

150

100

50

0

150

DISCHARGE, IN CUBIC FEET PER SECOND

5678

DECEMBER 1999

13 14 15 16 17 18 19 20

23 24 25

JUNE 1998

JANUARY 1999

Figure 17. Nitrate concentrations at 56th Avenue (14206900) during three storms, Fanno Creek, Oregon, June 1998 to 

December 1999. 

Y-axis minimum for discharge is shifted below zero to allow low flow to be portrayed. 
Summary 23

Insufficient data were collected during this study 

to further investigate the hypotheses presented here 

regarding ground-water interactions with Fanno Creek 

during individual storms, and the possible sources of 

phosphorus or nitrogen. Multiyear data reveal that the 

likely sources for SRP appear to be deep ground water 

during the summer, with a possible shallow 

ground-water flushing and diluting that occurs during 

storms, whereas nitrate increases during winter as 

shallow ground-water exchange increases, but 

decreases during summer. Nitrate may be high during 

winter when nitrification and mineralization in the soils 

are increased and uptake decreased, but lower during 

summer due to high uptake in soils and streams and 

decreased nitrification. Therefore, the two nutrients 

apparently have different source waters (deep and 

shallow ground water), as well as different 

nonconservative processes that affect their occurrence 

and concentrations during different seasons. Future 

investigations to clarify these processes could include 

explicit measurement of nutrient dynamics in ground 

water in riparian and near-stream environments, the 

response of ground water to precipitation, and further 

definition of hydrologic pathways during storms. 

SUMMARY

Multiple water samples were collected at three 

sites in Fanno Creek, an urban creek in Portland, 

Oregon, during three storms (one each in early 

summer, fall, and winter) from 1998 to 1999. Samples 

were analyzed for nutrients, bacteria, various measures 

of particulates and solids in water, and biochemical 

oxygen demand (BOD). Stream discharge was 

continuously gaged at two of the sites (Fanno Creek at 

56th Avenue, Fanno Creek at Durham Road), and at the 

third site (Fanno Creek at Scholls Ferry Road near 

Allen Boulevard) it was estimated on the basis of 

instantaneous staff plate readings and discharge 

measurements. Discharges during the sampling periods 

were not exceptionally high but were typical of most 

other storms during their respective seasons, with the 

first storm (June 1998) having the most discrete, single 

storm hydrograph, and the winter and fall storms 

(January and December 1999) each having highly 

variable flow with several discharge peaks. Discharge 

at 56th Avenue was the most flashy due to its relatively 

high gradient, and discharge at downstream sites, 

particularly Durham Road, was somewhat attenuated. 

A general matrix of Spearman’s correlations 

among all variables and all samples indicated that 

measures of particulates in water (Total Solids [TS], 

Total Suspended Solids [TSS], Total Volatile 

Suspended Solids [TVSS], and turbidity) were 

significantly and positively correlated (p<0.01) with 

discharge, total phosphorus (TP), BOD, and (with the 

exception of TS) E. coli bacteria. These correlations 

indicated that phosphorus, bacteria, and oxygendemanding substances were associated largely with 

particulate materials suspended and transported 

downstream by the storm runoff. Controlling these 

particulate materials may therefore offer an opportunity 

to control water-quality constituents that are regulated 

under a Total Maximum Daily Load (TMDL) that has 

been promulgated for Fanno Creek. TSS, as a principle 

measurement of solids that is regulated under the 

TMDL, was positively correlated with TP (rho about 

0.9) and discharge (rho about 0.7), was weakly 

correlated with E. coli bacteria (rho about 0.4), weakly 

and negatively correlated with nitrate-nitrogen (rho

about -0.3), and was not correlated with soluble 

reactive phosphorus (SRP). Furthermore, the pattern of 

higher particulate concentrations on the rising limb of 

the stream hydrographs indicated that most of the 

suspended sediment may have been supplied primarily 

from in-stream processes (bank erosion or 

resuspension of bed sediment) and/or from nearby 

upland sources rather than transport from distant 

upland sources. Existing storm drains may have shortcircuited the routing process, however, so some of the 

upland sources may have contributed 

disproportionately to the rising limbs of the discharge 

and sediment hydrographs.

Concentrations of E. coli bacteria exceeded the 

State of Oregon single sample criterion in almost all 

samples. TP concentrations exceeded the TMDL 

guidance criterion in most samples. Concentrations of 

TP, TS, and E. coli were greatest and most variable at 

56th Avenue, the most upstream site. Despite 

increasing discharges, peak loads were similar at 

upstream and downstream sites, indicating that sources 

along the creek were offset by deposition or other 

losses along the length of the creek, or that additional 

sources from upstream to downstream were minimal. 
24 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99

Dissolved constituents, including total dissolved 

solids (TDS), SRP, nitrate-plus-nitrite-nitrogen (NO3-

N), and ammonia (NH3-N), were not correlated with 

discharge, although NH3-N was correlated with 

measures of particulates (TS, TSS, TVSS) and with TP. 

Sources for NH3-N may therefore have included 

particulate organic material transported by the storm. 

The pattern of SRP concentrations was robust, with 

considerably less variation over storm hydrographs 

than for TP, although the overall SRP load did increase 

as discharge increased. These patterns suggested a 

ground water source for SRP in Fanno Creek that is 

separate from the sources for particulate P captured by 

the TP analysis. 

In general, concentrations of NO3-N were lower 

during the summer storm than the fall and winter 

storms, possibly reflecting plant or algal uptake in 

riparian areas and in the stream, or denitrification by 

microbial communities in stream margins, during the 

growing season. NO3-N concentrations typically were 

highest during fall and winter baseflow, with 

concentrations being temporarily diluted during storm 

runoff, a pattern common to streams in the Willamette 

River Valley. Correlations between NO3-N and TVSS, 

TSS, BOD, TP, SRP, and E. coli bacteria were negative 

and statistically significant, and NO3-N was positively 

correlated with TDS, reflecting the dilution of NO3-N 

during storm runoff. 

Analysis of data in this study has posed 

additional questions regarding nutrients and 

particulates in Fanno Creek that could merit additional 

investigation. There are indications that ground-water 

flow is a variable, but important, source for phosphorus 

and nitrate during low- and high-flow periods, 

respectively. Naturally occurring, stable isotopes could 

be used to investigate interactions of ground water and 

stream water, and nutrient dynamics associated with 

them, to determine the relative importance of deep and 

shallow flow paths, and to refine the understanding of 

the role of precipitation in the stream’s hydrologic 

response during storms. Suspended sediment appears 

to originate from in-stream or near-stream sources, but 

these conclusions are tenuous because of a lack of data 

targeted specifically at this question, and because the 

response of sediment to high flow has been poorly 

documented in highly modified, urban streams such as 

Fanno Creek. Additional synoptic sampling, preferably 

during several storms and at many sites, could help to 

define the relative importance of tributaries and 

upstream regions compared with downstream and instream sediment sources. Sources of bacteria also were 

difficult to ascribe from the data in this study, but new 

microbiological techniques, such as the use of RNA 

and DNA signatures to identify contributing animals 

(including humans), may provide opportunities for 

more definitive investigations. Additionally, streambed 

sediments could be sampled for bacteria during nonstorm periods to determine the potential size of the 

bacterial “pool” that is resuspended and transported 

downstream during storms. Finally, data on nearstream land use, including the size and character of 

riparian areas, could be used in conjunction with 

various investigations mentioned above to help refine 

the role of riparian vegetation in reducing inputs of 

sediments, bacteria, and nutrients. These and other 

studies targeted at specific questions could help refine 

the understanding of the effects of different 

management options on the sources and transport of 

particles, nutrients, and bacteria in Fanno Creek. 

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26 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99

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http://www.deq.state.or.us/wq/wqrules/wqrules.htm.

———2001b, Tualatin River subbasin total maximum daily 

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U.S. Geological Survey Water-Supply Paper 2175, 

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Appendix A 27

APPENDIX A.—QUALITY ASSURANCE 

PROGRAM

Quality Assurance Samples

Various types of quality control samples were 

collected and analyzed in addition to the environmental 

samples. These included equipment blank, method 

blank, end-plate blank, trip blank, replicate, field split, 

laboratory split, interlaboratory split, and standard 

reference samples as described below:

Equipment Blank Samples—Used to test for 

contamination introduced by the sampling 

equipment, one equipment blank was collected 

per storm event. Laboratory deionized (DI) 

water was poured into sampling containers that 

had been cleaned according to standard 

procedures, and was subsequently composited, 

subsampled, filtered, and analyzed identically 

to environmental samples. For bacteria 

samples, a special buffer media rather than DI 

water was used for blank samples. Equipment 

blank samples were initially prepared in the 

field at a sampling site.

Method Blank Samples—Used to test for 

contamination introduced during analysis, 

method blank samples have been used 

routinely as part of the quality assurance 

program in the CWS water-quality laboratory. 

Laboratory deionized water is poured directly 

into sample containers in the laboratory, and 

subsequently processed along with 

environmental samples using standard 

procedures. 

End-plate Blank Samples—Used to 

determine if any carryover occurs in the 

laboratory from one E. coli filter to the next, 

this test was used after processing all bacteria 

samples from a particular storm event. Sterile 

phosphate buffer media (a nutrient mixture 

typically used to grow bacterial cultures) was 

passed through the stainless steel apparatus 

used to filter bacteria samples, and the 

resulting filtrate tested for bacterial colonies as 

any standard sample. 

Trip Blank Samples—Used to test for 

contamination obtained in transit, one trip 

blank was included per storm event. Trip 

blanks were samples of DI water or sterile E. 

coli phosphate buffer media that were prepared 

in the laboratory prior to sampling, and 

transported to and from the field during 

sampling, with subsequent analysis according 

to standard procedures. Trip blanks were not 

processed through any of the sampling 

equipment. 

Sampling Method Replicate Samples—At 

the Durham Road site, one additional sample 

per storm was collected using standard USGS 

depth- and width-integrated clean sampling 

techniques and equipment. Results from this 

sample were used as a check against sampling 

bias from the weighted bottle sampler. The 

weighted bottle sampler was also used for 

multiple vertical pulls across a stream transect, 

with the individual subsamples composited 

together. 

Sequential Replicate Samples—Used to test 

the replicability of the sampling method and 

the variability over the hydrograph. One 

replicate sample was collected during each 

storm using the same methods as ambient 

environmental samples, but was collected 

immediately after the environmental sample 

was taken.

Field Split Samples—Used to assess the 

combined variability of field and analytical 

methods, an environmental sample was 

collected and split into two samples in the field 

(from the churn splitter) for separate analysis.

Laboratory Split Samples—Used to assess 

the variability in the analytical method, 

environmental samples were split in the 

laboratory and analyzed separately. 
28 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99

Interlaboratory Split Samples— Used to 

assess the accuracy of the analytical method, 

one sample per storm was split in the field for 

analysis by separate laboratories. Split samples 

were processed by the Oregon Department of 

Environmental Quality (ODEQ) laboratory in 

Portland and the USGS National Water Quality 

Laboratory in Denver, Colorado (NWQL). 

Samples for dissolved constituents provided to 

the USGS and ODEQ laboratories were 

filtered using 0.45 micron pore-size capsule 

filters according to standard USGS protocols 

(Wilde and Radtke, 1998). Samples for E. coli

were analyzed by the Oregon Health Division 

Laboratory. 

Standard Reference Samples— Used to 

assess the accuracy of the analytical method, a 

sample of known concentration of an analyte in 

blank water is submitted by the USGS to the 

CWS laboratory on a regular basis. The CWS 

accepts Standard Reference Samples (SRS) 

monthly from the Oregon District and 

semiannually from the USGS Branch of 

Quality Systems (BQS). Samples from the 

Oregon District are submitted only to the CWS 

laboratory and to the NWQL, whereas samples 

from the BQS program are compared with 

dozens of laboratories nationally. 

Quality Assurance Results

Results of quality control tests are provided in 

table A1 and are discussed below.

Blanks—On the basis of blank samples, there 

was no evidence of contamination that would 

compromise the analysis of Fanno Creek storm 

data. Among all chemical analyses of 

equipment and trip blanks (n=8), the only 

detection was for nitrate-N at a concentration 

of 0.015 mg/L during storm 2, a value that was 

close to the analytical reporting limit of 0.01 

mg/L during that period and below the 

reporting limits for the other storms sampled. 

Of the physical analyses (turbidity and 

suspended solids), there were a few low-level 

detections at and slightly above the detection 

limits. These were more than an order of 

magnitude below environmental 

concentrations observed during storms. Hence, 

bias from low-level contamination did not 

interfere with the analysis of data for this 

report.

Replicates and splits—Data from all replicate 

and split tests are shown in table A1. Relative 

difference between replicates was greater than 

10 percent in approximately a quarter (45 of 

175 replications) of the analyses, but was 

generally acceptable overall. Most of the 

higher relative differences originated from 

variability of field processing and from 

differences among laboratories. The field 

sampling methods (method replicates) tended 

to have similar or lower variability than simple 

splits of individual samples in the field (field 

splits), which indicates that representative 

samples could be obtained reliably using the 

weighted bottle sampler as was done for all 

environmental samples. 

Differences among laboratories are not 

surprising, and the opportunities for 

differences are greater by including three 

replicates (CWS, ODEQ, and USGS 

laboratories) in the tests from January and 

December 1999 rather than two replicates as in 

most other types of QA tests performed 

(table A1). Among the nutrient analyses, the 

ODEQ and USGS labs appeared to be 

intermittently biased high for NH3-N, and the 

CWS lab was consistently highest for NO3-N 

and SRP. There was no discernible pattern for 

TP. Only 2 bacteria samples were split between 

CWS and ODEQ (actually, the Oregon Health 

Division). One was qualitatively coded by 

ODEQ as having a concentration greater than 

600, a result that is consistent with the value 

2,100 counts/mL reported by CWS. For the 

other sample, CWS’ result was over an order of 

magnitude greater than ODEQ’s. On the basis 

of these limited data, the CWS lab appeared to 

produce higher counts of E. coli bacteria than 

the other laboratory. However, the data are 

insufficient to conclusively compare laboratory 

performance for bacteria samples. 

One sequential replicate, from 56th Avenue on 

June 24, 1998, indicates the high temporal 

variability in water chemistry during storms 
Appendix A 29

(table A1). During the 20 minutes that elapsed 

between the primary sample and the sequential 

replicate on that date, stream stage dropped 

from 9.95 to 9.83 feet, and discharge decreased 

from 38 to 30 ft3/s (not shown in table A1). 

Streamflow at 56th Avenue changes rapidly 

(fig. 2), and accordingly the initial sample on 

June 24 had substantially higher 

concentrations for most constituents that are 

frequently associated with suspended 

sediments (turbidity, TS, TSS, TP, E. coli) than 

the replicate had. Rather than indicating 

variability in sampling and analytical methods, 

these data indicate the rapid changes that are 

likely to occur in stream quality during storm 

conditions at such flashy sites, and suggest that 

actual temporal variations due to transient 

conditions can be more important than 

variability introduced by field and analytical 

methods. 

Dissolved nutrients (NH3-N, NO3-N, and SRP) 

tended to have among the least variability 

overall. In contrast, two constituents that had 

the highest variability overall, turbidity and 

bacteria, are both commonly associated with 

suspended sediment. Other constituents often 

associated with sediment concentrations, 

including suspended solids (TS and TSS) and 

TP, had relatively low variability overall, 

indicating that the analytical data for these and 

most other constituents were reliable and can 

be used quantitatively in this report. On the 

basis of these data, values for turbidity and 

bacteria should be viewed with care and are 

primarily used in this report in a qualitative 

manner. 

Standard Reference Samples—Results of 

semiannual (1998–2001) SRS comparisons by 

BQS indicate that the CWS overall is a good 

laboratory, and nutrient analyses are typically 

of good to excellent quality. On a scale of 0 to 

4, indicating poor (0), questionable (1), 

satisfactory (2), good (3), and excellent (4) 

quality, average ratings for NO3, NH3, SRP, 

and TP were 3.57, 3.63, 3.25, and 2.71, 

respectively (U.S. Geological Survey, Branch 

of Quality Systems, written commun., August 

2001). The most questionable results were for 

TP, although those data remained satisfactory 

to good and did not indicate any systematic 

bias. No other constituents analyzed in this 

study were included in the BQS interlaboratory 

comparison.

Results of the monthly SRS program, which 

also includes a native water sample split 

between the CWS and USGS laboratories, are 

in agreement with the results of the quarterly 

BQS program. For the months immediately 

preceding, during, and immediately following 

the storms sampled for this study, CWS 

analytical data showed good precision and 

accuracy, with almost no consistent biases 

evident. Results for nutrient SRS samples (low, 

medium, and high concentration ranges) were 

overwhelmingly within 10% of their expected 

values. SRS samples that were more than 10% 

different from the expected values included 

one sample for NH3-N (+60% in low 

concentration SRS), two samples for TP (-15–

25% in low concentration SRS), and one 

sample for NO3-N (~ 1 order of magnitude 

lower than expected in a high concentration 

SRS). The NO3-N sample was investigated in 

depth by the CWS laboratory and no errors 

were found, so it appears that the SRS sample 

was improperly prepared. Four sets of 

duplicate native-water samples (1 for TP, 2 for 

SRP, and 1 for NH3-N) had higher 

concentrations (30%-450%) compared to those 

for the same samples reported by the USGS 

NWQL, but in each case the two duplicates 

analyzed by CWS agreed closely (within 5% of 

each other) so it is likely that the NWQL 

results were erroneously low. Finally, 

detections were noted for NH3-N, TKN, and 

SRP in certified blank water on one occasion 

each (0.011, 0.025, and 0.013 mg/L, 

respectively), at concentrations below those 

reported in this study, so bias due to 

contamination is not considered a problem. 
30 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99 Table A1. Replicate sample results and relative percent differences during storm samplings, 1998–99 [Relative difference was calculated as 100*(range in replicate concentrations)/(average of replicate concentrations). Relative differences greater than 10 percent are bolded. Parameter abbreviations are described in the glossary or in table 2. CWS, Clean Water Services Laboratory; USGS, U.S. Geological Survey Laboratory, Denver, CO; ODEQ, Oregon Department of Environmental Quality Laboratory, Portland, OR. sample codes: N, normal; MR, method replicate (compares CWS vertical grab composite sampler and USGS equal width increment sampling methods); R, field replicate; SR, sequential replicate; LS, within-laboratory split; IS, interlaboratory split. Value qualifying codes: E, Estimated value; Q, Questionable value, poor quality control; G, Actual value is known to be greater than the value given; NA, not applicable] Site Date Time Sample code Turbidity Cond- Lab BODRate BOD5 BODUlt COD TS TDS TSS TVSS NH3-N NO3-N TP SRP E. Coli Method replicates Durham 6/24/98 20:30

N 26 21.5 196 105 91 0.036 0.304 0.302 0.052 6400

Replicate 6/24/98 20:30 MR 26 19.7 200 117 83 0.037 0.306 0.257 0.054 6700

Relative Difference (percent) 0.0 8.7 2.0 10.8 9.2 2.7 0.7 16.1 3.8 4.6

Durham 1/15/99 9:10

N 30 17.2 166 123 43.2 0.059 1.06 0.189 0.029 880

Replicate 1/15/99 9:10 MR 36 16.6 162 122 40.4 0.062 1.09 0.189 0.028 900

Relative Difference (percent) 18.2 3.6 2.4 0.8 6.7 5.0 2.8 0.0 3.5 2.2

Durham 12/7/99 11:30

N 42 88 0.0683 2.24 7.96 18.9 180 74 106 0.031 0.647 0.236 0.049 1,700

Replicate 12/7/99 11:30 MR Q 44 88 0.0760 2.06 6.53 18.9 184 79 105 0.03 0.641 0.242 0.05 1,400

Relative Difference (percent) 4.5 0.0 10.7 8.4 19.7 0.0 2.2 6.5 0.9 3.3 0.9 2.5 2.0 19.4

Sequential replicates

Allen Blvd 6/24/98 19:50

N 27 102 16.7 120 92 27.5 0.044 0.56 0.203 0.044 Q 11,000

Allen Blvd 6/24/98 20:10 SR 28 102 19.9 120 94 26 0.044 0.558 0.192 0.046 9,400

Relative Difference (percent) 3.6 0.0 17.5 0.0 2.2 5.6 0.0 0.4 5.6 4.4 20.0

56th Ave. 6/24/98 10:10

N 128 51 28.9 504 90 414 0.097 0.502 1.06 0.076 36,000

56th Ave. 6/24/98 10:40 SR 108 48 33.6 364 60 304 0.089 0.502 0.858 0.085 25,000

Relative Difference (percent) 16.9 6.1 15.0 32.3 40.0 30.6 8.6 0.0 21.1 11.2 36.1

Allen Blvd 1/15/99 20:30

N 36 117 0.065 1.50 5.46 21.9 204 88 12.4 0.054 1.19 0.255 0.033 680

Allen Blvd 1/15/99 20:40 SR 38 127 0.072 1.42 4.69 21.6 202 87.6 13.2 0.059 1.29 0.26 0.034 680

Relative Difference (percent) 5.4 8.2 11.1 5.5 15.2 1.4 1.0 0.5 6.2 8.8 8.1 1.9 3.0 0.0

Field Splits

Allen Blvd 12/6/99 20:55

N 13 113 14.3 112 6.2 1.2 0.037 0.907 0.102 0.049 1,200

Replicate 12/6/99 20:55

R 13 118 18.4 108 6.4 1.6 0.034 0.914 0.102 0.047 1,000

Relative Difference (percent) 0.0 4.3 25.1 3.6 3.2 28.6 8.5 0.8 0.0 4.2 18.2

56th Ave. 1/14/99 3:30

N 48 104 32.7 148 41.2 7.6 0.069 0.876 0.187 0.026 1,800

Replicate 1/14/99 3:30

R 48 104 32.8 140 41.6 8 0.071 0.954 0.19 0.027 1,700

Relative Difference (percent) 0.0 0.0 0.3 5.6 1.0 5.1 2.9 8.5 1.6 3.8 5.7

Durham 1/18/99 12:30

N 78 80 18.1 176 67 8.5 0.029 1.07 0.278 0.051 E ,1500

Replicate 1/18/99 12:30

R 44 81 18.2 168 46 5.5 0.031 1.07 0.287 0.051 2,100

Relative Difference (percent) 55.7 1.2 0.6 4.7 37.2 42.9 6.7 0.0 3.2 0.0 33.3
Appendix A 31

In-lab splits:

Durham 6/24/98 13:15 N 28 140 29.2 252 125 127 0.113 0.417 0.39 6300Split 6/24/98 13:15 LS 28 140 29.1 248 116 132 0.114 0.412 0.411 6200

Relative Difference (percent) 0 0 0.3 1.6 7.5 3.9 0.9 1.2 5.2 1.6

56th Ave. 6/24/98 16:10 N 25 77 18.1 100 82 18 0.038 0.673 0.18 Q 14,000Split. 6/24/98 16:10 LS 25 77 17.7 98 79 19 0.038 0.67 0.181 Q 15,000

Relative Difference (percent) 0 0 2.2 2.0 3.7 5.4 0.0 0.4 0.6 6.9

Durham 12/6/99 12:50 N 20 128 16.9 154 98 55.8 0.051 0.718 0.041Split 12/6/99 12:50 LS 20 128 17.1 154 97 56.8 0.048 0.712 0.038

Relative Difference (percent) 0 0 1.2 0.0 1.0 1.8 6.1 0.8 7.6

56th Ave. 12/7/99 17:55 N 15 128 15.3 122 116 6.2 E 0.016 1.44 0.051Split 12/7/99 17:55 LS 15 128 16.8 128 122 6.4 E 0.015 1.43 0.05

Relative Difference (percent) 0 0 9.3 4.8 5.0 3.2 6.5 0.7 2.0

Durham 12/7/99 9.31 N 35 10.4 192 109 0.038 0.547 0.249 0.051 2600Duplicate 12/7/99 9.31 LS 35 10.6 194 109 0.038 0.548 0.245 0.052 2100

Relative Difference (percent) 0 1.9 1 0.0 0.0 0.2 1.6 1.9 21.3

Interlab Split:

Allen Blvd 6/24/98 13:25 CWS 66 36.7 284 79 205 31 0.087 0.501 0.589 0.049Allen Blvd 6/24/98 13:25 IS-ODEQ 129 39 350 90 270 100 0.12 0.48 0.35 0.039

Relative Difference (percent) 64.6 6.1 20.8 13.0 27.4 105.3 31.9 4.3 50.9 22.7

Allen Blvd 1/14/99 12:50 CWS 124 15.4 162 122 40 0.059 1.19 0.168 0.025 1100Allen Blvd 1/14/99 12:50 IS-USGS 135 101 0.072 0.871 0.137 0.026Allen Blvd 1/14/99 12:50 IS-ODEQ 15 140 33 0.08 0.92 0.19 0.026 44

Relative Difference (percent) 8.5 2.6 14.6 18.8 19.2 29.9 32.1 32.1 3.9 184.6

Allen Blvd 12/7/99 8:15 CWS 85 218 105 0.036 0.861 0.288 0.055 2100USGS 12/7/99 8:15 IS-USGS 91.6 0.032 0.755 0.308 0.039ODEQ 12/7/99 8:15 IS-ODEQ 89 210 120 0.08 0.734 G 600

Relative Difference (percent) 7.5 3.7 13.3 97.3 16.2 6.7 34.0 NA

Table A1. Replicate sample results and relative percent differences during storm samplings, 1998–99—Continued[Relative difference was calculated as 100*(range in replicate concentrations)/(average of replicate concentrations). Relative differences greater than 10 percent are bolded. Parameter abbreviations are described in the glossary or in table 2. CWS, Clean Water Services Laboratory; USGS, U.S. Geological Survey Laboratory, Denver, CO; ODEQ, Oregon Department of Environmental Quality Laboratory, 

Portland, OR. sample codes: N, normal; MR, method replicate (compares CWS vertical grab composite sampler and USGS equal width increment sampling methods); R, field replicate; SR, sequential replicate; LS, within-laboratory split; IS, interlaboratory split. Value qualifying codes: E, Estimated value; Q, Questionable value, poor quality control; G, Actual value is known to be greater than the value 

given; NA, not applicable]

Site Date Time Sample code Turbidity Cond- Lab BODRate BOD5 BODUlt COD TS TDS TSS TVSS NH3-N NO3-N TP SRP E. Coli
32 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99 APPENDIX B.—WATER QUALITY DATA FROM FANNO CREEK, OREGON [Site details are given in table 1. Numbers in square brackets are Clean Water Services (CWS) parameter codes; ft3/s, cubic feet per second; ft, feet; oC, degrees Celsius; NTU, nephelometric turbidity units; SC, specific conductance; uS/cm, microsiemens per centimeter; DO, dissolved oxygen; mg/L, milligrams per liter; BOD, biochemical oxygen demand; d-1, per day; BOD5, 5-day BOD; BODult, ultimate BOD; TS, total solids; TDS, total dissolved solids; TSS, total suspended solids; TVSS, total volatile suspended solids; NH3-N, ammonia-nitrogen; NO3-N, nitrate-plus-nitrite-nitrogen; TP, total phosphorus; SRP, soluble reactive (ortho- phosporus; E. coli, escherechia coliform bacteria; --, not measured; Q, questionable] STORM 1, JUNE 1988 CWS sample number Site name Date and time Flow (ft3/s) [61] Gauge height (ft) [65] Temp (oC) [10] Turb- idity (NTU) [76] SC

(μS/cm)

[95]

DO

(mg/L) 

[299]

BOD 

rate

(d-1)

[--]

BOD5

(mg/L) 

[310]

BODULT

(mg/L)

[319]

pH

[400]

TS

(mg/L) 

[500]

TDS

(mg/L) 

[515]

TSS

(mg/L) 

[530]

TVSS

(mg/L) 

[535]

NH3-N

(mg/L) 

[608]

NO3-N

(mg/L) 

[631]

TP 

(mg/L)

[ 665]

SRP 

(mg/L) 

[671]

E. coli

(/100 mL) 

[31648]

9802238 56th 6/23/98 15:50 0.84 8.86 14.8 6 181 9.6 -- -- -- -- 150 148 2.2 0.6 0.029 0.87 0.097 0.040 E 15009802239 56th 6/24/98 09:07 43 10.01 13.8 40 72 9.5 -- -- -- -- 1040 92 948 130 .117 .62 2.23 .059 160009802240 56th 6/24/98 10:10 38 9.95 13.8 128 51 9.5 -- -- -- -- 504 90 414 60 .10 .50 1.06 .076 360009802241 56th 6/24/98 12:35 5.2 9.21 14.0 41 55 9.4 -- -- -- -- 142 66 76 12 .062 .56 .36 .074 320009802242 56th 6/24/98 14:49 1.9 9.0 14.0 31 69 9.2 -- -- -- -- 106 78 28 4.5 .048 .63 .23 .062 Q 180009802243 56th 6/24/98 16:10 1.5 8.96 14.5 25 77 9.0 -- -- -- -- 100 82 18 3.5 .038 .67 .18 .055 Q 140009802244 56th 6/24/98 19:00 1.1 8.91 14.9 18 94 8.7 -- -- -- -- 102 93 9.4 1.6 .034 .73 .14 .049 140009802245 56th 6/25/98 08:25 .81 8.86 13.6 7.3 149 8.6 -- -- -- -- 124 121 2.8 0.4 .032 .87 .10 .046 32009802228 Allen 6/23/98 16:50 3.52 .5 17.7 6 176 9.2 -- -- -- -- 140 134 6.0 1.4 .034 .51 .11 .035 5809802229 Allen 6/24/98 09:15 10.31 .68 15.2 15 165 8.2 -- -- -- -- 154 120 34 6.0 .092 .54 .21 .061 E 85009802230 Allen 6/24/98 12:20 84.5 1.78 14.7 78 109 8.8 -- -- -- -- 458 92 366 49 .10 .50 .84 .046 E 95009802231 Allen 6/24/98 13:25 46.74 1.25 14.9 66 100 8.6 -- -- -- -- 284 79 205 31 .087 .50 .59 .049 160009802232 Allen 6/24/98 16:50 14.51 .76 15.2 35 99 8.8 -- -- -- -- 134 84 50 9.0 .055 .53 .28 .047 Q 110009802233 Allen 6/24/98 19:50 6.85 .6 15.8 27 102 8.3 -- -- -- -- 120 92 28 5.0 .044 .56 .20 .044 Q 110009802234 Allen 6/24/98 22:20 6.85 .6 15.2 25 104 8.3 -- -- -- -- 118 100 19 3.5 .040 .58 .18 .042 Q 83009802235 Allen 6/25/98 09:05 4.70 .54 14.6 18 119 7.8 -- -- -- -- 118 108 11 1.5 .050 .66 .16 .040 56009802236 Allen 6/25/98 15:20 6.07 .58 15.0 16 127 8.7 -- -- -- -- 124 111 13 2.8 .070 .72 .16 .041 53009802218 Durham 6/23/98 17:55 12.3 1.86 18.0 5.5 221 8.8 -- -- -- -- 172 168 3.6 0.8 .036 .49 .13 .065 5209802219 Durham 6/24/98 10:30 107 3.38 15.0 36 126 8.5 -- -- -- -- 308 109 199 25 .145 .41 .51 .069 53009802220 Durham 6/24/98 13:15 142 3.79 15.7 28 140 7.9 -- -- -- -- 252 125 127 15 .113 .42 .39 .058 63009802221 Durham 6/24/98 15:55 145 3.83 15.7 37 120 7.7 -- -- -- -- 262 97 165 21 .072 .36 .47 .061 140009802222 Durham 6/24/98 19:30 105.7 3.36 16.9 26 142 7.8 -- -- -- -- 196 105 91 11 .036 .30 .30 .052 64009802223 Durham 6/24/98 23:00 61.5 2.76 16.7 23 145 7.7 -- -- -- -- 178 120 58 8.0 .042 .47 .25 .055 42009802224 Durham 6/25/98 10:00 25.9 2.16 15.9 23 128 7.4 -- -- -- -- 144 111 33 6.3 .173 .53 .20 .062 33009802225 Durham 6/25/98 15:55 28.1 2.2 15.7 12 145 8.3 -- -- -- -- 124 113 11 2.2 .040 .48 .14 .048 3300
Appendix B 33

APPENDIX B.— WATER QUALITY DATA FROM FANNO CREEK, OREGON—CONTINUED

STORM 2, JANUARY 1999

CWS

sample

number

Site 

name

Date 

and time

Flow 

(ft3/s) 

[61]

Gauge

height

(ft) 

[65]

Temp 

(oC)

[10]

Turbidity

(NTU) 

[76]

SC

(μS/cm)

[95]

DO

(mg/L) 

[299]

BOD 

rate

(d-1)

[--]

BOD5

(mg/L) 

[310]

BODULT

(mg/L)

[319]

pH

[400]

TS

(mg/L) 

[500]

TDS

(mg/L) 

[515]

TSS

(mg/L) 

[530]

TVSS

(mg/L) 

[535]

NH3-N

(mg/L) 

[608]

NO3-N

(mg/L) 

[631]

TP 

(mg/L)

[ 665]

SRP 

(mg/L) 

[671]

E. coli

(/100 mL) 

[31648]

9901021 56th 1/13/99 12:50 1.8 9.00 8.4 8.9 167 10.6 0.10 1.4 3.4 7.4 156 149 6.6 2.4 0.054 1.8 0.081 0.027 2609901022 56th 1/13/99 23:40 8.7 9.35 8.0 68 124 11.2 .13 5.0 10 7.4 236 111 125 22 .106 1.2 .40 .037 23009901023 56th 1/14/99 03:30 2.9 9.08 8.1 48 104 11.0 .09 2.4 6.8 7.3 148 107 41 7.6 .069 .88 .19 .026 18009901024 56th 1/14/99 07:35 13.3 9.49 8.3 62 100 11.2 .09 2.2 6.3 7.4 218 113 105 17 .069 .89 .31 .030 20009901025 56th 1/14/99 14:30 20.1 9.64 9.2 68 99 9.7 .10 3.2 7.8 7.3 350 113 237 26 .077 .85 .44 .030 28009901026 56th 1/15/99 13:15 3.1 9.10 8.7 15 145 10.8 .08 0.7 2.2 7.4 146 143 3.2 0.4 .049 1.6 .090 .028 5409901027 56th 1/15/99 19:10 17.9 9.58 8.6 33 129 11.1 .09 2.0 5.5 7.4 224 117 107 14 .062 1.4 .25 .030 30009901028 56th 1/16/99 10:20 69.2 10.30 6.4 152 61 11.6 .08 3.9 11.6 7.0 832 52 780 64 .049 .52 1.13 .043 52009901029 56th 1/16/99 16:30 12.5 9.47 7.7 39 115 11.4 .06 0.9 3.6 7.1 164 139 25 2.8 .037 1.7 .19 .052 41009901030 56th 1/17/99 09:50 76.1 10.37 6.6 112 58 11.7 .08 2.8 8.6 7.2 666 96 570 44 .036 .51 1.09 .040 40009901011 Allen 1/13/99 13:35 9 0.65 8.2 22 161 10.8 .09 1.1 3.1 7.3 160 146 14 2.4 .053 1.6 .11 .023 1809901012 Allen 1/14/99 00:40 18.0 0.83 8.1 28 157 10.9 .13 2.2 4.8 7.3 210 140 70 8.8 .063 1.6 .20 .029 7009901013 Allen 1/14/99 06:32 14.5 0.76 8.2 33 146 10.8 .06 1.1 3.8 7.4 172 134 38 5.6 .062 1.5 .16 .028 9209901014 Allen 1/14/99 12:50 17.4 0.81 8.6 31 124 9.6 .09 1.8 5.1 7.2 162 122 40 6.4 .059 1.2 .17 .025 11009901015 Allen 1/15/99 14:00 15.6 0.78 8.7 24 144 10.9 .05 0.80 3.6 7.2 154 141 13 2.0 .054 1.6 .13 .027 4109901016 Allen 1/15/99 20:30 -- -- 8.4 36 117 10.9 .06 1.5 5.5 7.2 204 116 88 12.4 .054 1.2 .26 .033 6809901017 Allen 1/16/99 11:10 128 2.33 7.0 76 89 11.0 .10 3.0 7.8 6.9 476 78 398 31 .045 .79 .54 .038 25009901018 Allen 1/16/99 17:15 62.0 1.47 7.4 76 96 11.2 .06 1.4 5.2 7.0 224 130 94 12 .042 1.2 .33 .042 24009901019 Allen 1/17/99 10:50 135 2.42 7.2 64 102 11.2 .07 1.7 5.8 7.1 380 129 251 20 .038 1.2 .45 .039 9509901020 Allen 1/18/99 11:50 100 1.99 8.1 64 98 10.7 .08 1.6 4.9 7.0 218 118 100 10.4 .038 1.4 .28 .051 12009901001 Durham 1/13/99 14:40 30.6 2.25 8.2 23 183 10.3 .08 1.3 4.1 7.3 204 160 44 6.0 .058 1.4 .15 .027 3309901002 Durham 1/14/99 02:30 56.2 2.68 8.2 22 171 10.9 .14 2.0 3.9 7.4 174 149 25 3.6 .063 1.4 .12 .028 4609901003 Durham 1/14/99 08:55 83.4 3.07 8.2 32 148 10.7 .08 1.5 4.3 7.4 190 134 56 8.4 .070 1.1 .16 .027 6409901004 Durham 1/15/99 09:10 73.9 2.94 8.7 30 131 9.6 .07 1.3 4.4 7.2 166 123 43 6.4 .059 1.1 .19 .029 8809901005 Durham 1/15/99 17:25 58.1 2.71 8.5 28 148 10.6 .06 0.90 3.4 7.3 160 140 20 3.2 .060 1.2 .14 .028 4409901006 Durham 1/16/99 12:05 304 5.40 7.2 66 90 10.8 .10 2.4 6.1 7.1 250 103 147 15 .052 .69 .33 .033 9009901007 Durham 1/16/99 18:10 310 5.45 7.2 60 87 11.0 .06 1.3 5.2 7.1 196 102 94 10 .045 .73 .30 .041 13009901008 Durham 1/17/99 11:35 279 5.18 7.0 48 94 11.0 .07 1.3 4.5 7.1 216 104 112 10 .040 .83 .28 .037 10009901009 Durham 1/18/99 12:30 584 7.62 8.1 78 80 10.0 .09 1.8 5.0 7.1 176 109 67 8.5 .029 1.1 .28 .051 E 15009901010 Durham 1/19/99 11:30 339 5.71 8.2 44 91 10.6 .08 1.3 3.7 7.1 162 108 54 5.6 .032 1.2 .19 .043 620
34 Phosphorus and E. coli and Their Relation to Selected Constituents During Storm Runoff Conditions in Fanno Creek, Oregon, 1998-99 APPENDIX B.— WATER QUALITY DATA FROM FANNO CREEK, OREGON—CONTINUED STORM 3, DECEMBER 1999 CWS sample number Site name Date and time Flow (ft3/s) [61] Gauge height (ft) [65] Temp (oC) [10] Turb- idity (NTU) [76] SC

(μS/cm)

[95]

DO

(mg/L) 

[299]

BOD 

rate

(d-1)

[--]

BOD5

(mg/L) 

[310]

BODULT

(mg/L)

[319]

pH

[400]

TS

(mg/L) 

[500]

TDS

(mg/L) 

[515]

TSS

(mg/L) 

[530]

TVSS

(mg/L) 

[535]

NH3-N

(mg/L) 

[608]

NO3-N

(mg/L) 

[631]

TP 

(mg/L)

[ 665]

SRP 

(mg/L) 

[671]

E. coli

(/100 mL) 

[31648]

9907662 56th 12/5/99 20:00 1.3 8.89 9.0 5.5 153 10.3 0.07 1.0 3.4 7.2 128 127 1.4 0.4 E .018 0.92 0.057 0.046 2609907663 56th 12/6/99 02:30 5.41 9.16 8.7 6 143 10.2 .08 1.4 4.3 7.3 120 115 5.2 .6 .021 .68 .070 .043 5409907664 56th 12/6/99 09:50 6.93 9.22 8.7 18 71 10.7 .08 1.9 5.6 7.1 82 25 5.0 E .020 .45 .14 .048 41009907665 56th 12/6/99 20:00 2.3 8.98 9.1 8 125 10.4 .07 1.0 3.6 7.4 114 112 2.2 .2 E .011 .90 .079 .045 22009907666 56th 12/7/99 07:35 37.2 9.91 7.4 36 66 11.2 .07 1.9 6.1 6.8 184 125 59 6.0 .022 .72 .26 .065 23009907667 56th 12/7/99 17:55 5.1 9.14 8.9 15 128 10.5 .07 0.9 3.3 7.1 122 116 6.2 1.2 E .016 1.4 .10 .051 19009907668 56th 12/8/99 10:15 5.0 9.15 8.4 9 154 10.8 .09 1.0 2.7 7.4 130 126 4.0 .4 .024 1.5 .080 .047 6309907669 56th 12/8/99 13:30 15.1 9.47 8.3 14 111 10.7 .09 2.3 6.2 7.3 126 97 29 5.8 .043 1.1 .12 .046 E 18009907652 Allen 12/5/99 20:45 8.4 0.64 8.6 7 147 10 .10 1.7 4.3 7.0 126 122 4.0 1.0 .030 1.1 .076 .046 4309907653 Allen 12/6/99 03:10 14.0 0.75 8.5 7 143 9.9 .08 1.6 4.9 7.1 130 125 5.4 .8 .029 .84 .092 .048 6509907654 Allen 12/6/99 12:00 29.3 0.99 8.8 17 118 10.4 .09 1.6 4.7 7.1 138 105 33 4.8 .035 .83 .13 .047 11009907655 Allen 12/6/99 20:55 14.5 0.76 8.8 13 113 10.2 .08 1.5 4.3 7.0 112 106 6.2 1.2 .037 .91 .10 .049 12009907656 Allen 12/7/99 08:15 82.3 1.75 7.7 50 85 G 11.0 .08 2.3 6.8 6.7 218 113 105 13 .036 .86 .29 .055 21009907992 Allen 12/7/99 11:04 62.7 1.48 7.7 37 85 12.8 -- -- -- 7.3 162 96 66 7.6 .036 .94 .22 .059 33009907657 Allen 12/7/99 17:10 32.6 1.04 8.4 30 106 10.6 .08 1.4 4.5 6.8 140 119 21 2.8 .037 1.3 .17 .064 29009907658 Allen 12/8/99 10:50 15.1 0.77 8.3 17 142 10.5 .09 1.3 3.5 7.1 142 129 13 2.0 .042 1.7 .13 .054 7009907659 Allen 12/8/99 14:00 22.6 0.89 8.3 23 133 10.4 .12 2.1 4.6 7.1 150 126 24 4.0 .047 1.5 .16 .059 9009907642 Durham 12/5/99 21:38 36.5 2.36 8.4 11 159 9.8 .08 1.3 4.2 7.1 134 123 11 1.6 .069 .94 .094 .048 5209907643 Durham 12/6/99 03:50 58.6 2.72 8.6 13 144 9.9 .08 1.8 5.3 7.2 124 105 19 2.8 .061 .80 .10 .046 4909907644 Durham 12/6/99 12:50 110 3.41 8.7 20 128 10.3 .09 1.9 5.0 7.2 154 98 56 7.2 .051 .72 .16 .041 7009907645 Durham 12/6/99 21:40 68.5 2.86 8.9 18 124 10.1 .09 2.0 5.5 7.2 128 96 32 5.2 .052 .70 .14 .044 5609907993 Durham 12/7/99 09:31 261 5.01 7.6 35 80 12.4 -- -- -- 7.4 192 83 109 16 .038 .55 .25 .051 26009907646 Durham 12/7/99 11:30 254 4.94 7.8 42 88 10.2 .07 2.2 8.0 6.9 180 74 106 13 .031 .65 .24 .049 17009907647 Durham 12/7/99 19:10 160 3.99 8.2 36 94 10.9 .08 1.7 5.2 6.9 154 98 56 6.8 .029 .82 .20 .054 12009907648 Durham 12/8/99 11:30 62.9 2.78 8.4 20 132 10.3 .09 1.3 3.6 7.2 136 120 17 2.7 .045 1.1 .35 .062 6309907649 Durham 12/8/99 14:30 89.4 3.15 8.2 23 128 10.4 .10 1.9 4.9 7.2 146 114 32 5.4 .054 .99 .16 .055 610
Appendix B 35
Anderson and Rounds

Printed on recycled paper

WRIR 02-4232 PHOSPHORUS AND E. COLI AND THEIR RELATION TO SELECTED CONSTITUENTS DURING STORM RUNOFF

CONDITIONS IN FANNO CREEK, OREGON, 1998-99