Evaluation of Planning Alternatives 

for Maintaining Desirable 

Dissolved-Oxygen Concentrations 

in the Willamette River, Oregon 

By David A. Rickert, Frank A. Rinella, 

Walter G. Hines, and Stuart W. McKenzie 

RIVER-QUALITY ASSESSMENT OF THE WILLAMETTE RIVER BASIN~ OREGON 

GEOLOGICAL SURVEY CIRCULAR 715-K 

1980 
United States Department of the Interior 

CECIL D. ANDRUS, Secretary 

Geological Survey 

H. William Menard, Director 

Library of Congress Cataloging in Publication Data 

Main entry under title: 

Evaluation of planning alternatives for maintaining desirable dissolved-oxygen concentrations in the Willamette River, Oregon. 

(River-quality assessment of the Willamette River basin, Oregon) (Geological Survey 

Circula.r 715-K) 

Bibliography: p. 

1. Water quality management-Oregon-Willamette River. 2. Water-Dissolved oxygen. 

I. Rickert, David A., 1940- II. Series. III. Series: United States. Geological Survey. 

Circular 715-K. 

QE75.C5 no. 715-K [TD224.07] 557.3'08s [ 614.7 &72'097953] 79-607057 

Free on application to Branch of Distribution, U.S. Geological Survey 

1200 South Eads Street. Arlington, Va. 22202 
FOREWORD 

The American public has identified the enhancement and protection of river 

quality as an important national goal, and recent laws have given this commitment considerable force. As a consequence, a considerable investment has been 

made in the past few years to improve the quality of the Nation's rivers. Further 

improvements will require substantial expenditures and the consumption of 

large amounts of energy. For these reasons, it is important that alternative 

plans for river-quality management be scientifically assessed in terms of their 

relative ability to produce environmental benefits. To aid this endeavor, this 

circular series presents a case history of an intensive river-quality assessment 

in the Willamette River basin, Oregon. 

The series examines approaches to and results of critical aspects of riverquality assessment. The first several circulars describe approaches for providing 

technically sound, timely information for river-basin planning and management. Specific topics include practical approaches to mathematical modeling, 

analysis of river hydrology, analysis of earth resources-river quality relations, 

and development of data-collection programs for assessing specific problems. 

The later circulars describe the application of approaches to existing or potential 

river-quality problems in the Willamette River basin. Specific topics include 

maintenance of high-level dissolved oxygen in the river, effects of reservoir 

release patterns on downstream river quality, algal growth potential, distribution of toxic metals, and the significance of erosion potential to proposed future 

land and water uses. 

Each circular is the product of a study devoted to developing resource information for general use. The circulars are written to be informative and useful to 

informed laymen, resource planners, and resource scientists. This design stems 

from the recognition that the ultimate success of river-quality assessment 

depends on the clarity and utility of approaches and results as well as their basic 

scientific validity. 

Individual circulars will be published in an alphabetical sequence in the 

Geological Survey Circular 715 series entitled "River-Quality Assessment of 

the Willamette River Basin, Oregon." 

J. S. Cragwall, Jr. 

Chief Hydrologist 

III 
Cover: Willomette River as it winds through Portland, Oregon. Photograph taken by 

Hugh Ackroyd. 
CONTENTS 

Pa~e 

Foreword ---------------------------------------------------------------- III 

Albstract ----------------------------------------------------------------- K1 

Introduction -------------------------------------------------------------- 1 

Background ---------------------------------------------------------- 1 

Purpose and scope ----------------------------------------------------- 1 

DO sources and demands ------------"'---------------------------------- 3 

R~ 185-120 ----------------------------------------------------- 4 

R~ 120-50 ------------------------------------------------------- 4 

R~ 50-10 ------------------------------------------------------- 4 

R~ 10-1.5 ------------------------------------------------------- 4 

WIRQALS DO ~odel -------------------------------------------------- 4 

Explanation of base condition --------------------------------------------- 5 

Streamflow ----------------------------------------------------------- 5 

Waste loadings ------------------------------------------------------- 5 Planning implications ___ ___ _ _ _ __ _ _ _ __ _ __ __ ___ __ __ _ __ _ __ __ _ _ _ _ __ __ __ __ __ __ _ 8 

BOD impact -------------------------------------------------------- 8 

Almmonia impact ---------------------------------------------------- 9 

Impact of low-flow augmentation --------------------------------------- 10 

Benthic-oxygen-demand impact _ __ _ __ _ __ __ _ __ _ _ _ _ _ __ _ _ ___ _ __ ___ _ _ _ __ _ __ _ 13 

Planning control curves --------------------------------------------------- 14 

Two-factor control curves --------------------------------------------- 14 

Variation of point-source NOD loading and streamflow -------------- 14 

Variation of point-source BODult loading and streamflow ------------ 16 

Variation of point-source NOD and BODult loadings ----------------- 17 

Three-factor control curves -------------------------------------------- 17 

Explanation------------------------------------------------------ 17 

Alnalysis of curve shapes ------------------------------------------- 18 

Use ------------------------------------------------------------- 19 

Summary and conclusions ------------------------------------------------- 22 

Alcknowledgments --------------------------------------------------------- 24 

References--------------------------------------------------------------- 24 

Supplement Al-Summary of the characteristics and application ranges of the 

WIRQALS DO Model ---------------------------------------------- 27 

Supplement B-~odel boundary point ( R~ 86.5) waste loadings for selected 

streamflows -------------------------------------------------------- 28 

Point-source BODult loading ------------------------------------------- 28 

NPS BO Dult loading _________________________________________ --- __ __ __ 28 

Point and NPS NOD loadings ----------------------------------------- 29 

Point-source NOD loading ___________ --------------- _________ _____ 29 

NPS NOD loading ----------------------------------------------- 29 

Supplement C-Decay rates for computing carbonaceous oxygen demands ____ 30 

FIGURE 

ILLUSTRATIONS 

1. ~ap of Willamette River basin, Oregon, emphasizing principal 

tributaries, major reservoirs, and river-mile locations on 

main stem Willamette River ----------------------------

v 

Page 

2 
Page 

FIGURES 2-15. Graphs showing: 

TABLE 

2. Composite DO profile of the Willamette River observed 

under 1973 steady low-flow conditions ----------- 3 

3. DO profiles for selected point-source BODult loadings__ 9 

4. DO profiles computed for the base condition and predicted for a BOD:; municipal effluent standard of 10 

mg/L ----------------------------------------- 10 

5. DO profiles for selected point-source NOD loadings____ 11 

6. DO profiles for selected levels of streamflow at Salem__ 12 

7. DO profiles for selected Salem stream flows and pointsource ammonia loadings ----------------------- 13 

8. DO levels at various river-mile locations for selected 

combinations of Salem streamflow and point-source 

NOD loading ---------------------------------- 15 

9. DO levels at various river-mile locations for selected 

combinations of Salem streamflow and point-source 

BODult loading -------------------------------- 16 

10. DO levels at various river-mile locations for selected 

combinations of point-source loadings of BODu, t 

and NOD ------------------------------------- 18 

11. DO levels at RM 72.0 for selected combinations of Salem 

streamflow, point-source BODult loading, and pointsource NOD loading --------------------------- 19 

12. DO levels at RM 55.2 for selected combinations of Salem 

streamflow, point-source BODult loading, and pointsource NOD loading --------------------------- 20 

13. DO levels at RM 28.6 for selected combinations of Salem 

streamflow, point-source BODult loading, and pointsource NOD loading --------------------------- 21 

14. DO levels at RM 12.0 for selected combinations of Salem 

streamflow, point-source BODu, t loading, and pointsource NOD loading --------------------- _______ 22 

15. DO levels at RM 5.0 for selected combinations of Salem 

streamflow, point-source BODu, t loading, and pointsource NOD loading ---------------------------- 23 

TABLES 

1. Summary of BODu, t loadings, NOD loadings, and information 

used for base-condition inputs to the WIRQAS DO Model 

2. Base condition, dry-weather BODult loading to the main stem 

Willamette River ___________________ -- _ ------------ __ --

3. Approximate base condition, dry-weather ammonia nitrogen ·loadPage 

5 

6 

ing to the main stem Willamette River ------------------ 6 

4. Oxygen demands exerted in the modeled segment of the Willamette River under base conditions ----------------------- 7 

VI 
SYMBOLS 

[Definition of symbols and abbrzviated terms use:l in th:s circular] 

BOD-carbonaceous biochemical oxygen demand 

BODu~t-ultimate BOD 

BOD~5-day BOD at 20°C 

DO-dissolved oxygen 

N-nitrogen 

N 0 D-nitrogenous-oxygen demand 

NPS-nonpoint source 

kn-nitrogenous deoxygenation rate (log10) in river 

k.-river carbonaceous deoxygenation rate (log10), corrected for temperature 

kt-carbonaceous deoxygenation rate (logw) as measured in BOD bottle at 20oC 

RM-river mile 

STP-municipal sewage-treatment plant 

CONVERSION FACTORS 

Factors for converting inch-pound units to the International System of Units ( Sl) are given below to four significant figures. 

Inch-pound 

English 

ft' Is (cubic feet per second) 

lb (pounds) 

mi (miles) 

Multiply by 

2.832xlo-:: 

4.535xlo-l 

1.609 

VII 

Metric (Sf) 

m3/s (cubic meters per second) 

kg (kilograms) 

km (kilometers) 

Evaluation of Planning Alternatives for ,Maintaining 

Desirable Dissolved-Oxygen Concentrations 

in the Willamette River, Oregon 

By David A. Rickert, Frank A. Rinella, 

Walte'r C. Hines, and Stuart W. McKenzie 

ABSTRACT 

Basinwide secondary treatment of municipal and industrial waste waters has resulted in a dramatic increase of summertime dissolved-oxygen concentrations 

in the Willamette River. Rates of carbonaceous decay 

are low (0.03 to 0.06 per day), and point-source carbonaceous biochemical oxygen demand loadings now account for less than one-third of the satisfied oxygen 

demand. Nitrification is now the dominant cause of 

dissolved-oxygen depletion. Future achievement of dissolved-oxygen standards will require continued lowflow augmentation in addition to pollution control. A 

minimum summertime streamflow of 6,000 cubic feet 

per second at Salem gage will be needed even with increased removal of oxygen-depleting materials. The 

greatest immediate incremental improvement in dissolved oxygen can be made through reduction in pointsource industrial ammonia loading. The pros and cons 

of upgrading treatment efficiencies for carbonaceous 

biochemical oxygen demand removal would best be determined after the ammonia loading has been reduced. 

For the foreseeable future, there is no need for municipal advanced waste treatment to protect dissolvedoxygen levels in the Willamette River. 

INTRODUCTION 

BACKGROUND 

Historically, maintenance of high dissolvedoxygen (DO) concentration has been the critical problem in the Willamette River (fig. 1). 

During summer low-flow periods, the DO concentration in Portland Harbor was often zero 

(Velz, 1961; Gleeson, 1972), and for years, low 

DO levels inhibited the fall migration of salmon from the Columbia River. 

In recent years, summer DO levels have increased dramatically and fall salmon runs have 

returned. The improvement has resulted from 

a reduction in the loading of point-source carbonaceous biochemical oxygen demand (BOD), 

coupled with streamflow augmentation from 

storage reservoirs. However, the Oregon Department of Environmental Quality (DEQ) 

still regards maintenance of high DO levels as 

the factor of highest priority in planning the 

future of the Willamette River. 

Kl 

Today ( 1979) the Willamette is the largest 

river in the United States on which all pointsource discharges receive secondary wastewater treatment. The Willamette thus offers 

a unique opportunity to evaluate key alternatives for managing river quality. The primary 

concern is whether advanced waste treatment 

will be necessary to achieve desirable DO levels 

under future conditions of waste loading and 

streamflow. 

PURPOSE AND SCOPE 

This circular describes the impacts of various quality-planning alternatives on summertime DO levels in the Willamette River. Annually, the lowest DO concentrations occur during the summer with the low flow, high temperature conditions of July and August. This 

period is the one of most concern for river 

quality and therefore, the "critical condition" 

on which to base the design of waste-treatment 

and quality-management plans. 

This circular completes a three-set series on 

summertime DO conditions of the Willamette. 

Circular 715-I (Hines and others, 1977) provided a detailed data base and the interpretations necessary to describe the summertime DO 

regimen below river mile (RM) 86, the his-
w 

(!I 

z 

<( 

a: 

~ 0 

u 

II 

INDEX MAP OF OREGON 

I 

10 

10 

1 

I 

20 

I 

20 MILES 

I 

30 KILOMETERS 

w 

0 

<( 

~ <( 

u 

FIGURE 1.-Willamette River basin, Oregon, emphasizing principal tributaries, major reservoirs, and river-mile locations on main stem Willamette River. 

K2 
torical zone of DO depletion. Circular 715-J 

(McKenzie and others, 1979) followed by describing how data in Circular 715-I were used 

to calibrate and verify a DO model useful as a 

practical tool for assessing planning alternatives. 

To aid the reader, the following two sections 

provide brief synopses of ( 1) the summertime 

DO regimen <;>f the Willamette, and (2) the 

basic character of the verified DO model. 

DO SOURCES AND DEMANDS 

Figure 2 shows the predominant factors controlling DO concentrations in various segments 

of the Willamette River under summer lowflow conditions. The profile represents average 

daily DO concentrations measured in 1973 and 

is constructed with time of travel on the horizontal axis to permit examination of the rate 

of change in measured DO levels. 

Along the course of the Willamette River, 

the observed DO profile is the net balance of 

oxygen demands exerted and oxygen resources 

contributed. Nitrification, carbonaceous deoxygenation, and a "benthic demand" are the oxygen demands, whereas natural and augmented 

streamflow, tributary inflows, atmospheric reaeration, aeration at the Willamette Falls, and 

Columbia River water are the oxygen sources. 

As indicated in figure 2, the DO profile is influenced along the entire 187 miles (mi) by 

natural and augmented streamflow, atmospheric reaeration, and carbonaceous deoxygenation. In contrast, the other factors are involved only in the noted segments and locations. 

Before describing the segment-to-segment 

character of the DO profile, it is necessary to 

provide a brief background on the measured 

DO levels (see Supplement E, Circular 715-I). 

First, each DO level in figure 2 represents the 

average of at least 2 days of around-the-clock 

(diel) sampling. The values at many locations 

were computed from continuously recorded 

data, and for manually sampled sites, the 

levels represent the average of as many as 128 

samples. 

Second, diel DO variations resulting from 

algal photosynthesis and respiration occurred 

at each site represented in figure 2 (see Supplement E, Circular 715-I). Magnitudes of DO 

variations were small below RM 50, but farRIVER MILES ABOVE MOUTH 

187 39 28.6 1 7 12.8 1 0 7.0 6.0 3.5 1.5 0 

z 

0 

j: 

<( Discharge at Salem=6000 ft3fs 

~ 100 

1-

<( 

en 

1-

z 90 w 

u 

a: 

w 

CL. 

~ 80 

z' 

w 

C) 

>- 70 

X 

0 

Cl 

w 

> 60 ...J 

0 

en 

en 

c 50 

cat• on 

I

+- Nit.rifi--1 

Clackamas River 

Reaeration a~ Willamette Falls --

DO recovery 

1

-Benthic demand -+--1 Mixing ~ith.the-1 ~Columbia R1ver I I 

----Natural plus augmented streamflow; atmospheric reaeration; carbonaceous deoxygenation----• 

0 5 10 

TIME OF TRAVEL, IN DAYS 

15 

FIGURE 2.-Composite DO profile of the Willamette River under observed 1973 steady low-flow conditions. 

The profile is plotted on a time-of-travel basis to emphasize the relative rates that DO is removed or 

added in various reaches. Major controlling factors are noted for appropriate reaches. 

K3 
ther upstream, daily variations were large 

owing to growth of attached algae on the shallow, cobbly bottom. 

RM 185-120 

In figure 2, the average DO levels between 

Eugene-Springfield (RM 185) and Albany 

(RM 120) are consistently near 100-percent 

oxygen saturation, or about 9.4 milligrams per 

liter (mg/L) at the prevailing summer water 

temperatures of 18° to 19°C. The McKenzie 

River enters the Willamette at RM 175 but, 

with a DO saturation of 100 percent, does not 

cause any measurable change in DO levels. The 

impact of waste-water loads from municipalities and industries in Eugene-Springfield, Corvallis, and other smaller communities is discernible only in the immediate vicinity of outfalls. Because of the fairly light loading of ammonia, nitrification is insignificant, and the 

high atmospheric reaeration capability of the 

shallow fast-moving segment quickly counterbalances the slow rate of carbonaceous deoxygenation. 

RM 120-50 

Beginning at RM 114, the percentage of DO 

saturation decreases slowly, and then, below 

Salem (RM 85), it decreases rapidly. Between 

RM's 120 and 50, the level declines from nearly 

100 percent to 70 percent, a drop of approximately 2.5 mg/L at the prevailing water temperatures. The decrease results from large industrial loads of ammonia that induce the 

growth of nitrifying bacteria on the shallow, 

cobbly, diatom-encrusted river bottom. The bacterially induced nitrification proceeds at a high 

rate, outpacing the capacity of the river to replenish DO through atmospheric reaeration. 

RM 50-10 

Changes in average DO levels between RM 

50 to 10 are minor relative to the large decrease between RM 120 to 50. The observed 

DO variations include ( 1) an approximate 5-

percent increase in saturation caused by reaeration at Willamette Falls and the inflow of 

cool, highly oxygenated water from the Clackamas River, (2) a slight decline in percent 

saturation between RM's 21 and 12.8 resulting' 

from carbonaceous deoxygenation, and (3) a 

somewhat sharper decline between RM 12.8 to 

10 owing to the additive effects of carbonaceous 

deoxygenation and a benthic oxygen demand. 

Because the rate of carbonaceous deoxygenation is low, total reaeration effectively balances total deoxygenation and keeps the percentage of DO saturation at a fairly even level. 

RM 10-1.5 

Between RM's 10 and 6, there is a gradual 

decrease in percent DO saturation (7 percent) 

resulting from a combination of benthic demand and carbonaceous deoxygenation. Between RM 6.0 to 3.5, DO levels remain fairly 

constant (approximately 63 percent saturation 

or 5.4 mg/L). In the vicinity of RM 3.5, near 

the entrance to Multnomah Channel, DO levels 

begin to rise sharply owing to mixing with 

highly oxygenated Columbia River water. At 

RM 1.5, the DO level has risen to 74 percent 

saturation. Thereafter, DO continues to increase, finally reaching 97 percent saturation 

at the Columbia confluence. 

WIRQAS DO MODEL 

After testing several models, the one chosen 

for the study was that developed and used for 

more than 30 years by C. J. Velz. The basic 

model (Velz, 1970) is applicable to conditions 

of steady (invariable), nonuniform (changing 

cross-sectional geometry) , plug (non dispersive) flow. The computer program as formulated for the present study is named the 

WIRQAS (Willamette Intensive River-Quality 

Assessment Study) DO Model. 

The WIRQAS Model has been applied only 

for summer low-flow, high-temperature, 

steady-state conditions. The model was calibrated using 1974 waste-loading, streamflow, 

and water-temperature conditions and verified 

against similar data collected in 1973. Details 

of the model, the calibration, and the verification are presented in Circular 715-J. In addition, Supplement A of the present report provides a summary of the model's characteristics 

and application ranges. 

K4 
EXPLANATION OF BASE CONDITION 

STREAMFLOW 

Using the verified WIRQAS Model, a series 

of computer runs have been made to simulate 

an array of hydrologic and waste-loading conditions. Results of these runs were used to construct the "predictive control curves" presented in figures 3 through 15. All curves in 

these figures were computed around a selected 

base condition representing a Salem streamflow of 6,000 fV/s. This flow was selected as 

the comparative base for all figures because 

(1) the U.S. Army Corps of Engineers attempts to maintain this level as the minimum, 

summer low flow needed for navigation purposes, and (2) observations by the Oregon 

DEQ (Oregon Department of Environmental 

Quality, 1975) and the U.S. Geological Survey 

(Rickert and others, 1975) indicate this discharge is needed as a summertime minimum in 

order to achieve State DO standards. Water 

temperatures used for the base condition were 

those measured during the 1973 verification 

period when the average streamflow was 6,000 

fta/s. For all curves, DO saturation at the 

model boundary point (RM 86.5) was set at 

the 1973-74 average of 92 percent. 

WASTE LOADINGS 

In addition to a base-condition flow, it was 

also necessary to select among loading data 

measured during 1973 and 1974 to obtain an 

average summer condition defined by reliable 

data. The selected base-condition data are 

shown in table 1 where both point- and nonpoint-source (NPS) loadings of ultimate 

BOD (BODuit) and nitrogenous-oxygen demand 

(NOD) are referred to river-mile location. All 

loadings were computed using the base-condition flow of 6,000 ft 3 Is. The methods of computing the loadings are described in the footnotes for table 1, and the manner of selecting 

data to use in the computations is given below: 

TABLE 1.-Summary of BODutt loadings, NOD loadings, and information used for base-condition inputs to the 

WIRQAS DO Model 

Location 

(RM) Description of waste input 

86.5 Residual load in WilJamette River __ 

85.0 Boise Cascade Corp --------------

77.9 Salem STP ---------------------- 55.0 Yamhill River ------------------- 50.5 Newberg STP ------------------- 49.8 Publishers Paper Co -------------

39.0 Wilsonville STP ----------------- 35.8 Mollala River --------------------

33.0 Canby STP ---------------------- 28.4 Tualatin River ------------------- 28.0 Publishers Paper Co -------------

27.8 West Linn STP 1 ---------------- 27.6 Crown Zellerbach Corp -----------

25.0 Oregon City STP -------~--------

24.8 Clackamas River ----------------- 24.1 West Linn STP 2 ---------------- 20.2 Tryon Creek STP ----------------

19.9 Oak Lodge STP ----------------- 18.5 Kellogg Creek ------------------- 18.4 Johnson Creek ------------------- 18.4 Milwaukie STP ------------------ Total _______________ ---------- ___ _ 

[Computed for a Salem flow of 6,000 ft3/s] 

DO Flow (percent 

(ftll/s) saturation) 

6,000.0 24.9 

40.4 

62.5 

1.2 

18.0 .2 134 

.5 22.5 

19.9 .7 20.7 

4.3 1,100 

1.0 

5.7 

3.1 

1.0 

2.0 

2.1 

92 

10 

50 

90 

20 

10 

20 

100 

20 

90 

10 

20 

40 

50 

96 

50 

50 

50 

70 

80 

50 

Point 

source 1 •:l 

(lb/d) 

30,500 

13,100 

11,700 

900 

100 

7,300 20 

470 

70 2,300 

11,000 100 

4,900 

140 

170 

220 

120 

220 

83,330 

BODult load 

Nonpoint 

source3• 4 

(lb/d) 

51,700 

900 

930 

500 

9,300 

260 

40 

63,630 

Total 

(lb/d) 

82,200 

13,100 

11,700 

1,800 

100 

7,300 20 1,400 

70 2,800 

11,000 100 

4,900 

140 

9,300 

170 

220 

120 

260 

40 

220 

146,960 

Point 

source 

(lb/d) 

18,900 7 

70,300 

7,500 

96,700 

NOD load5,o 

Nonpoint 

SK>uree 

(lb/d) 

5,600 7 

5,600 

Total 

(lb/d) 

24,500 7 

70,300 

7,500 

102,300 

1 Based on point-source BODult loads discharged directly to the m!l.in stem Willamette River and into tributaries. Residual load at RM 86.5 represents the flow-routed sum of all upriver, individual, point-sotuce loads. Decay calculated from temperature corrected rates based on kr=0.06/d at 20°C. 2 All point-source BODnlt loads above RM 86.5 based on 1973 data. Loads below RM 86.5 based on 1974 data, except those less than 500 lb/d which were sampled in 1973. • 3 Based on BODu 1 t concentrations measured in Cascade Range tributaries above waste-water outfalls plus estimated NPS contributions from minor tributaries (that is, those with flows less than 100 ff1/s). Residual load at RM 86.5 represents the flow routed sum of all upriver, individual, NPS loads. Decay calculated ft·om temperature corrected rates based on kr=0.06jd at 20°C. 4 All NPS BODnt t loads represent averaged 1973-1974 data. 5 NOD loadings were calculated from ammonia-N data using an oxygen-to-nitrogen ratio of 4.33 (see Wezernak and Gannon, 1967). 6 In the modeled segment of rivet· ( RM's 86.5 to 5.0), measurable nitrification occurs only from RM 86.5 to 55.2. Therefore, NOD's are re- ported only for those ammonia loads that enter this 31.5-mi zone of nitrification. The dashed lines thus signify a lack of exerted nitro- genous demand rather than a lack of ammonia loading. 7 Residual point and NPS loads at RM 86.5 were based on an average ammonia-N concentration of 0.16 mg/L measured during eal'ly and mid-August 1974, when flows were about 6,760 ft'ljs. The NPS component was taken to be 0.04 mg.'L based on the average of meas- urements in major Cascade Range tributaries above known point sources. Th's concentration was converted to the reported NOD loading consistent with the base-condition flow of 6,000 ffl/s. The remaining 0.12 mg/L was assumed to be a point-source component that is flow independent. No flow routing of individual sources was possible owing to lack of ammonia decay rates above RM 86.5 .See Supplement B in this report for further details. 

K5 
1. Where available, 1974 BOD data were 

used for municipal and industrial waste-water 

discharges. Below RM 86.5, 1974 data were 

available for all point sources discharging 

more than 500 pounds (lb) ultimate BOD per 

day (BODuu/d). The 1974 data were the more 

reliable because of improvements in analytical 

technique. 

2. BOD data from 1973 were used for all 

point-source discharges above RM 86.5 and for 

the small discharges (less than 500 lb BODuu/ 

d) below this location. 

3. NOD loadings were computed from 

1974 ammonia data except for the Boise Cascade mill at RM 85.0. NOD for this source was 

based on the lower ammonia concentrations 

measured in 1973, because inspection of several years of records showed these were more 

representative of average summer conditions. 

4. For all tributaries, the flows, BODuit 

loadings, and DO levels were averaged from 

1973 and 1974 data. This was done because the 

summer of 1973 was unusually dry, whereas 

the summer of 1974 was quite wet. By averaging the data, more representative tributary 

conditions were obtained than those offered by 

either year's results. 

To evaluate the significance of the data in 

table 1, it was necessary to determine the quantities and percentages of point and NPS BODuit 

and NOD that entered the Willamette in various river segments. Table 2 shows such results 

for BODu1h and table 3 gives similar data for 

NOD. 

The important points in table 2 are that 

only 54 percent of the total BODuit is derived 

from point sources and that the point-source 

loadings are distributed fairly evenly over the 

TABLE 2.-Base condition, dry-weather BODu1 t loading to the main stem Willamette River 

[All point-source BODu1 t loads above RM 86.5 based on 1973 samples. Point-source loads below RM 86.5 based on 1974 data except those less than 500 lb/d which were sampled in 1973. All NPS BODu1 t loads represent averaged 1973-74 datal 

River segment 

(RM) 

187 -86.5 3 -------------------

86.5-52.0 --------------------- 52.o-26.5 --------------------- 26.5- 5.0 --------------------- Total -------------------

Point sources 1 

(municipal and industrial outfalls) 

Percentage Percentage 

BODult of point- of total (lb/d) source loading 

loading to river 

36,800 41 22 25,600 29 15 26,300 29 16 900 1 0.5 .89,600 100- 54 

Nonpoint sources 2 Total loading 

Percentage Percentage Percentage BODult of nonpoint- of total BODu1t by (lb/d) source loading (lb/d) segment loading to river 

65,100 85 39 101,900 61 

900 1 .5 26,500 16 

1,400 2 .5 27,700 17 

9,600 12 6 10,500 6 

77,000 100 46 166,600 100 

1 Outfalls discharging directly to main stem Willamette River plus flow-routed point-source loads discharged into tributaries. Of the total point-source loading, 41 percent is from municipal waste--water treatment plants and 59 percent is from industrial discharges. 2 Based on BODu1 t concentrations measured in Cascade Range tributaries above waste-water outfalls plus estimated NPS contributions from minor tributaries (that is, those with flows less than 100 ft1/s). 3 Loadings for the segment (RM's 187-86.5) differ from model input loadings at RM 86.5 (see table 1) owing to in-river decay. 

TABLE 3.-Approximate base condition, dry-weather ammonia nitrogen loading to the main stem Willamette 

River 

River segment 

(RM) 

187 -86.5 3 -------------------

86.5-52.0 ---------------------

52.o-26.5 --------------------- 26.5- 5.0 ---------------------

Total -------------------

[Based on data collected during the summer low-flow peri.ods of 1973-74] 

Point source 1 

(municipal and industrial outfalls) 

Lb/d 

as 

N 

14,500 4 

18,000 

2,800 

1,600 

36,900 

Percentage Percentage of point- of total source loading 

loading to river 

39 

49 

8 

4 

100 

37 

47 

7 

4 

95 

Lb/d 

as 

N 

1,500 

100 

150 

160 

1,910 

Nonpoint sources 2 

Percentage Percentage of nonpoint- of total source loading 

loading to river 

79 4.0 5 .3 8 .4 8 .4 100 5 

Total loading 

Lb/d Percentage as by N segment 

16,000 41 18,100 47 2,950 8 1,760 4 38,810 100 

1 Outfalls discharging either directly to Willamette River or into Middle Fork, McKenzie, Santiam, and Clackamas Rivers less than 20 mi from confluence with Willamette. 2 Estimated from nitrogen concentrations measured in tJ;ibutaries above waste--water outfalls. 3 Loadings for this segment (RM's 187-86.5) differ from model input loadings at RM 86.5 (see table 1) owing to in-river decay. 4 liijtrogen mass-balance calculations based on measured loadings and in-river concentrations indicate an undefined source contributed up to 12,000 lb/d of ammonia-N in the Albany-Millersburg area (RM 12G-114). DEQ and USGS are currently (1979) involved in a de-- tailed study of ammonia loading "between RM's 120 and 86.5. 

K6 
160.5 mi between Eugene (RM 187) and the 

Willamette Falls (RM 26.5). In addition, as 

described in Table 2, footnote 1, 41 percent of 

the total point-source loading is from municipal waste-water treatment plants, whereas 59 

percent is from industrial discharges. 

The important point from table 3 is the overwhelming contribution of point source (95 

percent) relative to NPS ammonia (5 percent) . Moreover, the data used to compile table 

3 show that about three-fourths of the pointsource ammonia comes from two sources : ( 1) 

the Boise Cascade mill at RM 85.0 and (2) a 

yet undefined, localized source in the AlbanyMillersburg area (RM 120-114) (see table 3, 

footnote 4) . 

Whereas tables 1-3 show the magnitude of 

waste-water loadings, table 4 summarizes the 

oxygen demands exerted by the loads in passage through the modeled river· segment of 

RM 86.5 to 5.0. From table 4, the total demand 

exerted by all sources is 177,900 lb/d. Based 

on the bottom row of data, the percentage contributions to this total are as follows: 

1. Point-source carbonaceous deoxygenation ---------------------- 28 

2. NPS carbonaceous deoxygenation 22 

3. Nitrification of point-source ammonia ------------------------ 32 

4. Nitrification of NPS ammonia __ 2 

5. Benthic-oxygen demand ________ 16 

Total _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 100 

The results show that oxidation of pointsource ammonia represents the largest oxygen 

demand in the modeled river segment. Moreover, because nitrification occurs at a very high 

rate (ku=0.7/d; see Supplement A of this report) and exclusively from RM 86.5 to 55, the 

nitrogenous demand induces a sharper and 

deeper depression in DO than do any of the 

other factors (see fig. 2) . In a similar manner 

to nitrogenous demand, the benthic oxygen demand is exerted exclusively within one segment 

of the river (RM 12.8-5.0). However, while 

significant, the impact of benthic demand on 

DO is far less dramatic than that caused by 

nitrification (fig. 2). 

In contrast to the other oxygen demands, 

carbonaceous deoxygenation is exerted over the 

entire river. Furthermore, the rate of exertion 

is low and, hence, the effect on the DO profile is less pronounced. The largest localized 

impact ~s between RM's 12.8 and 5.0, where 

tidal effects and river geometry cause slow 

travel times, thus enabling carbonaceous deoxygenation to occur for about 5 ~~~-

In evaluating the total impact of carbonaceous deoxygenation, it is important to note 

the relative proportion of the point and NPS 

demands. The importance arises because during summer low-flow conditions, NPS BODuit 

loading in the Willamette River represents essentially natural background demands that 

seemingly cannot be modified. This means, for 

base conditions, that only slightly more than 

one-half the materials causing carbonaceous 

deoxygenation are point-source derived and, 

therefore, amenable to reduction through 

waste-water treatment. 

TABLE 4.-0xygen demands exerted in the modeled segment of the Willamette River under base conditions 

[Base conditions represent a Salem flow of 6,000 ft a;s and the waste loadings given in table 1] 

River 

segment 

(RM) 

86.5-52.0 --------------- 52.0-26.5 --------------- 26.5- 5.0 ---------------

Total ------------

Point 

source 

Ob/d) 

4,700 

15,800 

29,000 

49,500 

Carbonaceous I 

Per- Nonpoint cent- s0111rce age (lb/d) 

5 

18 

33 

56 

4,700 

12,700 

21,300 

38,700 

Percentage 

5 

15 

24 

44 

Point 

110uree 

Ob/d) 

57,300' 

57,300 

Nitrogenous 2 

Per- Nonpoint cent- source age (lb/d) 

94 3,400 

Benthic a 

Per- Amount 

c:~; (lb/d) 

Percentage 

94 3,400 6 29,000 

29,000 100 

100 

Total 

Amount 

(lb/d) 

70,1()0 

28,500 

79,300 

177,900 

Percentage 

39 

16 

45 

100 

1 Computed assuming that all point- and nonpoint-source BODu 1 t loadings decay in the river at kr = 0.06/d above RM 55.2 and at 0.03/d below this location (see Supplement C of this report for discussion). 2 Computed using a first-order decay rate kn=0.7/d. Field data indicate that measurable nitrification occurs only between RM's 86.5 and 

55.2 of the modeled river segment. 3 As noted in the text, the "benthic demand" between RM's 12.8 and 5.0 is thought to represent a combination of several different types of oxygen exertion. The model treats part of the demand as a flowing load decayed at a rate of 0.1/d. Thus, the total computed benthic demand varies with flow, and the result reported here for base conditions (Salem flow=6,000 ft:!js) differs slightly from the value reported for calibration conditions (Salem flow=6,760 ft3/s) in tables 1 and 2 of Circular 715-J. 

K7 
PLANNING IMPLICATIONS 

As an aid to river-quality planning, the 

WIRQAS Model has been used to test planning 

alternatives concerning (1) BOD loading, (2) 

ammonia loading, (3) low-flow augmentation, 

and ( 4) the effects of possible removal or reduction of the "benthic oxygen demand" in 

Portland Harbor. This section defines the 

major implications of the alternatives by comparing DO profiles generated by the verified 

model with the reference base-condition profile. 

A fact the reader should bear in mind in 

examining the following illustrations (figs. 

3-7) is that, for ease of presentation, the DO 

profiles are plotted as a function of river location. Thus, unlike the profile in figure 2, the 

slopes of curves in specific subreaches do not 

represent the actual rates at which oxygen is 

added to or lost from the river. For example, 

the profiles in figures 3-7 suggest a rapid rate 

of oxygen depletion below Willamette Falls. 

Actually, the steepness of the curves is caused 

by the slow time of travel in the Tidal Reach 

(see Circular,7t5-I) rather than by an accelerated rate of oxygen depletion. 

Waste loadings and flow levels examined in 

figures 3-7 were selected to provide envelopes 

for summer low-flow conditions of probable 

future occurrence. Most likely, any future 

changes in point-source BODua loading will fall 

within a span of a 50 percent decrease to a 200 

percent increase around the base condition. 

The same reasoning holds for the examined 

range of point-source NOD loadings and for 

the investigated flow range of 3,260-10,000 

ft::/s. 

In developing figures 3-7 (and all subsequent 

curves), the assumption was made that no 

changes would occur in the location of wastewater outfalls. This was done because the location of possible new outfalls and changes in 

existing ones could not be fully anticipated. In 

addition, all waste sources were treated as receiving secondary treatment, and, except where 

noted, the percentages of loading increases or 

decreases were applied uniformly to all point 

sources. 

As previously noted, the base-condition DO 

profile is included in each of figures 3-7. Also 

included are the State DO standards, which 

change from segment-to-segment as follows 

(Oregon Department of Environmental Quality, 1975): (1) RM 0-26.5, 5 mg/L, to protect 

anadromous fish passage and population by 

resident fish; (2) RM 26.5-50, 6 mg/L, to protect anadromous fish passage and salmonid 

rearing; ( 3) RM 50-85, 7 mg /L, to protect 

salmonid fish rearing and spawning; and (4) 

above RM 85, 90 percent of saturation, to protect salmonid spawning. 

It should be noted in figures 3-7 that the DO 

levels computed for the base condition violate 

the standard between RM 64 to 50. This violation is caused almost entirely by nitrification, 

and more will be said about this in the following sections. 

BOD IMPACT 

The effect of BOD loading on summertime 

DO is reflected in figure 3. The curve labeled 

100 percent represents the average DO profile 

of the river at the flow, water temperatures, 

ammonia loading, and BOD loading representative of the base condition. The upper and 

lower curves represent the predicted DO profiles at 50 percent and 200 percent of the basecondition point-source BOD loading with all 

other variables held constant. 

The upper curve in figure 3 indicates that 

only a slight improvement in DO can be obtained by a 50 percent decrease of BOD loading from each point source in the basin. The 

predicted increase in DO would be less than 

5 percent of saturation near the downstream 

end of the Newberg Pool (RM 27) and about 5 

percent at RM 5, the low DO point in the river. 

In contrast, a doubling of BOD loading from 

each point source would depress DO by more 

than 5 percent of saturation at RM 27 and by 

more than 10 percent at RM 5. This increase 

in loading would also cause the violation of 

the State DO standard to increase in magnitude between RM 64 to 50. 

Figure 4 compares the base-condition profile 

with one representing the application of a 

BOD:. effluent standard of 10 mg/L to all municipal treatment plants discharging directly into 

the Willamette River. Such a standard, supposedly attainable by high-level secondary 

treatment,. is being considered by the Oregon 

K8 
100r-----------.------------.-----------.-----------.----------~ 

z 

Q 90 r 

~ 

a: 

:> 

r 

~ (/.) 

r 

z 

w 

u 

a: 80 w 

a.. 

~ 

zw 

(.!) 

>-

X 

0 

Cl 70 w 

> 

...J 

0 

(/.) 

(/.) 

Cl 

60 EXPLANATION 

----State DO standards, in mg/L 

or percent saturation 

5 mg/L 

100 80 60 40 20 0 

RIVER Ml LES ABOVE MOUTH 

FIGURE 3.-DO profiles for selected point-source BODuJt loadings. The profile labeled 100 percent results from the base condition defined in table 1. Flow ( 6,000 ft'/s at Salem), NOD 

loadings, and NPS BODult loadings held constant. 

DEQ. Application of the 10 mg/L standard to 

base conditions would decrease municipal summertime loading of BODuJt to the Willamette 

from about 30,400 to 17,400 lb/d. The largest 

individual decrease would be about 7,000 lb/d 

at the Salem municipal sewage-treatment 

plant (STP) (RM 77.9). The modeling results 

(fig. 4) indicate that the reduced loading would 

produce only minor in1provements in DO saturation, the maximum increase being 2 percent 

at RM 5. This virtual lack of improvement 

stems from ( 1) the small reduction attainable 

in the total loading of BOD111 t (about 9 percent), (2) the low rates at which BODuit is 

exerted in the river, and (3) the dispersed 

locations within the basin of the larger municipal waste-water treatment plants (see Circular 

715-I). 

AMMONIA IMPACT 

Figure 5 illustrates the effect of point-source 

NOD on summertime DO in the Willamette. 

Compared to the base condition, a one-third 

reduction in NOD loading would increase DO 

by about 5 percent of saturation near the 

lower end of the Upstream Reach (RM 55) 

and also at RM 27. ;Between RM's 64 to 50, 

the improvement in DO levels would enable the 

State DO standard to be met under base conditions. A two-thirds reduction in point-source 

NOD loading would substantially increase DO 

levels, by about 10 percent of saturation at 

RM's 55 and 27 and by more than 5 percent 

at RM 5. 

In contrast, increased NOD loading would 

cause rather drastic decreases in DO levels. An 

increase of point-source NOD loading to 150 

K9 
100~----------~----------~~----------.------------.------------

z 

0 90 f-

<{ 

a: 

::> 

f-

<{ 

C/) 

fz 

w 

u 

a: 80 w 

0.. 

~ 

z 

w 

l? 

>-

X 

0 

0 70 w 

> 

...J 

0 

C/) 

C/) 

0 EXPLANATION 

----State DO standards, in mg/L 

or percent saturation 

5 mg/L -------

100 80 60 40 20 0 

RIVER Ml LES ABOVE MOUTH 

FIGURE 4.-DO profiles computed for the base condition and predicted for a BOD~ municipal 

effluent standard of 10 mg/L. The effluent standard was applied (1) only to those municipal 

sewage treatment plants that discharge directly into the Willamette River and (2) with 

flow (6,000 ft3 /s at Salem), NOD loadings, and the industrial and NPS components of 

BODuit held at the base condition (see table 1). 

percent of the base condition would decrease 

the percent of DO saturation by about 8 percent at RM 55, 6 percent at RM 27, and 4 percent at RM 5. Furthermore, the resultant decreases would cause State DO standards to be 

violated from RM 72 to the Willamette Falls. 

The results illustrate two important points. 

First, over the modeled part of the Willamette, 

ammonia loading has its greatest effect on DO 

in the active zone of nitrification between RM's 

85 and 55. Thereafter, measurable nitrification 

ceases to occur and the upstream effects of the 

process are gradually diminished by atmospheric reaeration. Second, comparison of figures 3 and 5 indicates that point-source NOD 

loading has a greater influence on Willamette 

River DO than point-source BOD loading. At 

the comparative point-source loadings (BODutt 

=83,000 lb/d, NOD=96,700 lb/d, see table 1), 

this finding results primarily from the much 

greater rate at which NOD is exerted (kn 

=0.7/d, k,.=0.06 or 0.03/d). 

Most of the ammonia that is oxidized in the 

Willamette below RM 86 is discharged from 

the Boise Cascade mill at RM 85. Control of 

ammonia from this one source would greatly 

reduce the impact of nitrification on the DO 

regimen of the river. 

IMPACT OF LOW-FLOW AUGMENTATION 

The effect of flow augmentation is illustrated 

in figure 6, in which the base-condition profile 

KlO 
100~----------~----------~-----------.-----------,,---------~ 

z 90 percent Q 90 1-

<( 

a: 

=> 

1-

<( 

CJ) 

1-

z 

w 

u 

a: 80 w 

Q.. 

~ 

z. 

w 

\:) 

>-

X 

0 

Cl 70 w 

> _J 

0 

CJ) 

CJ) 

Cl 

60 

EXPLANATION 

----State DO standards, in mg/L 

or percent saturation 5 mg/L 

100· 80 60 40 20 0 

RIVER MILES ABOVE MOUTH 

FIGURE 5.-DO profiles for selected point-source NOD loadings. The profile labeled. 100 percent 

results from the base condition defined in table 1. Flow (6,000 ft3 /s at Salem), BODutt 

loadings, and NPS NOD loadings held constant. 

is compared with profiles predicted for 3,260, 

5,000, 8,000, and 10'-000 ft 3 ls (see Supplement 

B for discussion of waste-load computations at 

different flows). The profile for 3,260 ft:~ Is requires some mention. This discharge is near 

the lowest minimum monthly flow ever recorded for July under natural (nonaugmented) 

conditions (Velz, 1951). Moreover, predictions 

from a hydrologic model (Shearman, 1976) 

indicate that without flow augmentation, 

natural streamflow would have approximated 

this level during July of the unusually dry 

year of 1973. Because of difficulties with loading assumptions (see Supplement B under 

"NPS BO Duu Loading") , the 3,260 fV Is curve 

is considered as an estimate of the actual DO 

profile, rather than an accurate prediction. 

With this reservation, it is, nevertheless, presented to provide an important historical baseline indicating the drastic effect of natural 

drought flows and the importance of flow 

augmentation. 

Figure 6 shows the marked impact that flow 

augmentation has on river DO levels. At the 

3,260 ft 3ls discharge, the base-condition BOD 

and ammonia loadings would cause violations 

of State DO standards by wide margins at 

most locations. The estimated DO saturation 

levels at 3,260 ft 3 ls are about 25 percent less 

than the base condition (flow augmented to 

6,000 ft 3 ls) at RM 55 and about 20 percent 

less at RM's 27 and 5. 

At a flow of 5,000 ft 3 Is, the State DO standards would be violated between RM 70 to 50 

Kll 
100.-----------.-----------,-----------r-----------r---------~ 

z 

0 

f-

<( 

a: 

:::l 

~ 80 Cl) 

fz 

w 

u 

a: 

w 

0.. 

~ 

z 60 w 

(,:) 

>-

X 

0 

0 

w 

> 

....J 

0 EXPLANATION 

~ 40 

0 

---- State DO standards, in mg/L 

or percent !>aturation 

100 80 60 40 20 0 

RIVER Ml LES ABOVE MOUTH 

FIGURE 6.-DO profiles for selected levels of streamflow at Salem. Point-source BODult and 

NOD loadings held constant. 

by as much as 10 percent of DO saturation. 

Moreover, at this flow and these base-condition loadings, the DO standards would barely 

be met in the Newberg Pool and in the lower 

end of Portland Harbor. 

In evaluating increased flow augmentation, 

it should be recognized that improvements in 

quality are less dramatic as the DO profile is 

raised toward the level of saturation. Thus, increasing flow from 6,000 to 8,000 ft=: / s causes 

DO improvements of only slightly greater magnitude than that achieved through an increase 

from 5,000 to 6,000 ffl/s. At higher levels, an 

increase from 8,000 to 10,000 ffl/s results in 

only about half of the DO improvements obtained by moving from 6,000 to 8,000 ft='/s. For 

the base-loading condition, it appears that augmentation of flows to above 7,000 ft=>./s (computed but not shown) would not provide enough 

improvement in DO levels to warrant taking 

the water from competitive uses. Nevertheless, 

under future waste-loading conditions, augmented flows in excess of 7,000 ft:~ / s should 

always be investigated as a possible alternative 

to expensive, energy-consuming, advanced 

waste-treatment processes. 

Figure 7 illustrates the combined effects of 

reduced NOD loading and flow augmentation. 

Curve c relative to d shows the improvements in 

DO that would occur at a 3,260 ft~/s flow by 

applying an ammania-N effluent limit of 10 

mg/L at the Boise Cascade mill (RM 85.0) and 

the Salem STP (RM 77.9). The improvement 

is similar to that obtained by augmenting 

streamflow to 6,000 ft=l / s and maintaining the 

base-condition loading of ammonia (curve b 

relative to c). Comparison of curves a and b 

shows the DO improvement that would result 

from applying the same ammonia-N effluent 

limitation at a flow of 6,000 ft 3 /s. The result is 

a nearly 10 percent increase in DO saturation 

between RM 60 and 27, which would provide 

significant safety margins above the State 

standards. 

Curve c portrays a very significant finding 

for dry year conditions such as 1973. ·Even 

with complete secondary treatment and the 

Kl2 
100~----------~-----------.------------.------------.------------, 

z 

0 

r-

<{ 

a: 

~ 80 

<{ 

U) 

rz 

w 

u 

a: 

w 

CL. 

~ 

a 

6 mg/L b 

z 

w 

60 

3260 ft3/s, N H4 = Base condition 

t:) 

>- "" c 

X 

0 

0 d w 

> 

....J EXPLANATION 

~ 40 U) 

0 

---State DO standards, in mg/L 

or percent saturation 

100 80 60 40 20 0 

RIVER Ml LES ABOVE MOUTH 

FIGURE 7.-DO profiles for selected Salem streamflows and point-source ammonia loadings. Curve 

b results from the bas,e condition defined in table 1 for flow and NOD loading. Point-source 

BODu1 t loadings held constant. 

noted limitation on ammonia loading, low-flow 

augmentation would be necessary to ensure 

achievement of DO standards at several locations below RM 60. 

BENTHIC-OXYGEN-DEMAND IMPACT 

During 1970, benthal respirometer studies 

(John Sainsbury, written commun., 1970) of 

the lower Willamette River documented a 

benthic oxygen demand of 27,000-54,000 lb/d 

in the segment between RM's 13 and 7. The 

river at that time still received some raw 

sewage from combined sewer overflows and a 

moderate loading of fibers and other settleable 

solids from pulp and paper mills. Because these 

sources of solids were largely controlled by 

1972, it was anticipated that the benthic demand would be greatly reduced, if not eliminated, by 1974. However, during preliminary 

runs of the WIRQAS Model, predicted DO concentrations between RM's 13 and 5 were higher 

than those measured in the river, whereas 

predicted BODu1t concentrations were considerably lower. Further modeling tests suggested 

an undetermined oxygen demand of up to 

30,000 lb/ d in this segment. 

For lack of a better term, the demand is 

referred to in this circular as a benthic-oxygen 

demand, although field investigations conducted during 1973-1974 suggested the demand was both suspended and benthic in origin. Based on recent studies conducted by the 

U.S. Geological Survey (Steven E. Mellor, oral 

commun., USGS, Oregon District Office, Water 

Resources Division, Portland Oreg.), the demand has been tentatively proportioned as 

follows: 

1. ~4-lf1 due to "inplace" benthic-oxygen 

demand. 

2. llt-11.3 due to excess algal respirationthat is, 0:! consumption due to respiration is 

greater than photosynthetic 0 2 production ( for 

details see Rickert and others, 1977, and also 

Circular 715-I). 

K13 
3. 1A,-1h due to an unknown combination 

of (a) sewer overflows, (b) ship discharges, 

(c) navigation dredging, and (d) resuspension 

of benthic materials by tidal current and ship 

propwash. 

It is hoped that all or at least part of the 

demand can be eventually related to controllable sources. If so, management control of 

such sources would provide a means for improving summertime DO by as much as 8 percent of saturation at RM 5. 

~ 

PLANNING CONTROL CURVES 

Numerous planning insights can be gleaned 

from the predicted profiles in figures 3-7. However, the curves fail to portray the integration 

of various combinations of BODutt loading, 

NOD loading, and streamflow so tradeoffs can 

be evaluated for attaining desired DO levels 

at critical locations. 

To permit evaluation of alternative tradeoffs, an extensive series of DO profiles was 

prepared through numerous runs- of the 

WIRQAS Model. From the computer outputs, 

two groups of planning curves have been developed for convenient interpolation. In the 

first group, figures 8-10 integrate two factors, 

holding the third factor constant, whereas in 

the second group, figures 11-15 integrate all 

three factors. 

TWO-FACTOR CONTROL CURVES 

Figures 8-10 show predicted DO levels at 

five locations along the Willamette River where 

BODutt loading, NOD loading, and flow are 

varied two at a time. In each figure, as two 

factors are varied, the third is held constant at 

the base condition. 

VARIATION OF POINT~SOURCE NOD LOADING 

AND STREAMFLOW 

Figure 8 shows predicted percentages of DO 

saturation at Salem flows of 5,000 to 8,000 

ft 3 /s and point-source NOD loadings of 33 to 

150 percent of the base condition (BODutt 

loadings held constant). Five sets of curves, 

I-V, apply respectively to specific locations at 

RM's 72.0, 55.2, 28.6, 12.0 and 5.0, as designated at the top of the figure. The percentages 

of point-source NOD loadings are noted at the 

bottom of each set of curves. Within the figure, 

the four curves in each set refer to streamflow, 

designated from top to bottom as 8,000, 7,000, 

6,000, and 5,000 ft=:;s. To provide a reference, 

the base-condition point of 6,000 fta;s and 100 

percent NOD loading is noted by an open circle 

in each set of curves. 

Vertical movement within a curve set is representative of a change in streamflow. For example, at RM 28.6 (set III), movement from 

point A (the base condition) to point B represents an increase in flow from 6,000 to 7,000 

ft=1/s, and a consequent change in DO saturation from about 75 to nearly 80 percent. In contrast, movement downward from A to C represents a decrease in flow to 5,000 fp /s, which 

results in a predicted decrease to about 69 percent of DO saturation. 

Movement along a curve in figure 8 represents a change in NOD loading as reflected on 

the bottom scale. Movement from point A to 

D represents an increase of NOD loading to 

150 percent of the base condition and results in 

a predicted decrease in DO saturation from 75 

to 68 percent. In contrast, movement up the 

6,000 ft=1/s curve from A to E represents a 

decrease in NOD loading to 33 percent oj the 

base condition, which results in an increase in 

DO saturation to 84 percent. 

In figure 8, the shape of the curves in each 

set provides considerable insight into the interaction of streamflow and NOD loading in 

the control of river DO. The two factors have 

differing intensities of impact at the five locations as indicated by curve slopes and the vertical distances between curves. For example, 

the curves are steepest in set II at RM 55.2. 

Curve steepness is determined il). this figure 

by the effect of NOD loading. Thus, the results 

indicate that the impact of nitrification is 

greater at RM 55.2 than at any of the other 

four sites. Another observation is that the 

vertical distances between curves are greatest 

across the full range of NOD loading at RM 

5.0. Because the separation between curves is 

determined by the effect of streamflow, the observation indicates that the impact of flow 

augmentation is generally greater at RM 5.0 

than at the other four sites. 

The cone shape of the curve clusters in sets 

I and II changes to more generally parallel curves in sets III, IV, and V. This change reK14 
SET I 

z 

Q 

1-

<( 

a: 

:::> 

1-

<( 80 en 

1-

z 

w 

u 

a: 

w 

Q.. 

z 70 

SELECTED RIVER MILES ABOVE MOUTH 

1..--55.2--+1 

-I 

SET II 

l+---28.6--+1 

SET Ill SET IV 

j.--5.0 --+I 

SET V 

z' 

w 

<.!) 

>-

X 

0 

0 60 w 

> _. 

0 

en 

en 

0 EXPLANATION 

50 ----State DO standards (variable with location) 

® DO at the base condition 

s• Points A- E explained in text 

I I I I I I I I I I I I I I I I I I 

33 67 100 150 33 67 100 150 33 67 100 150 33 67 100 150 33 67 100 150 

SELECTED PERCENTAGES OF POINT-SOURCE NOD LOADING 

FIGURE 8.-DO levels at various river-mile locations for selected combinations of Salem streamflow and pomtsource NOD loading. Point-source BODutt loading held constant at the base condition. 

fleets a downriver decrease in the interactive 

effects of streamflow and NOD, and is consistent with the fact that measurable nitrification 

does not occur below RM 55. The impact of 

NOD on the curve shapes at RM's 28.6, 12.0, 

and 5.0 is a downriver translation of an upstream effect. However, beginning at RM 28.6, 

the effect of nitrification is less at each consecutive site as indicated by the fact that the 

curves become more parallel. 

The relationship between flow and NOD results from their effects on intermediate factors. 

The level of streamflow affects time-of-passage 

(for NOD exertion), the initial quantity of 

DO, and several aspects of the reaeration potential. The loading of NOD directly affects 

the magnitude of oxygen deficit, which, in 

turn, is a driving force behind reaeration potential (Further details on these and other 

factors are available in Supplement A of Circular 715-I.). 

In figure 8, the horizontal dashed line in each 

set of curves indicates the State DO standard. 

In set I, the base condition is a fair distance 

above the standard. However, as previously 

noted, the base condition violates the DO 

standard in the segment between RM's 64 and 

50. Therefore, in set II at RM 55.2, the circle 

indicating the base condition falls below the 

dashed line. 

Referring back to figure 5, nitrification is 

the cause of the rapid DO decrease between 

RM's 85 and 55. Therefore, three management 

alternatives are available for dealing with the 

K15 
SELECTED RIVER MILES ABOVE MOUTH 

1+-72.0-----+1 I+- 55.2 ---+1 1+--28.6-----+1 1+--12.0---+l I+-- 5.0 --+1 

SET I SET II SET Ill SET IV SET V 

z 

Q 

1-

<( 

a: 

::> 

1-

<( 

(/) 

1-

z 

w 

u 

a: 

w 

a.. 

~ 70 

z' 

w 

(.!) 

>-

X 

0 

0 60 w 

> 

....I 

0 

(/) 

(/) 

0 EXPLANATION 

50 ----State DO standards (variable with location) 

® DO at the base condition 

40 I I I I I I I I I I I I 

50 100 150 200 50 100 150 200 50 100 150 200 50 100 150 200 50 100 150 200 

SELECTED PERCENTAGES OF POINT-SOURCE ULTIMATE BOD LOADING 

FIGURE 9.-DO levels at various river-mile locations for selected combinations of Salem streamflow and pointsource BODult loading. Point-source NOD loading held constant at the base condition. 

situation in the 14-mi segment between RM's 

64 and 50: (1) reduce the NOD loading, (2) 

increase streamflow, and (3) lower the DO 

standard. Assuming that the third option is 

unacceptable, figure 8 can be used to determine 

the NOD loading/flow tradeoffs for achieving 

the standard at the base condition. To just 

meet the standard at RM 55.2, the base-condition NOD loading would need to be cut by 

about 20 percent at a flow of 6,000 ft 3 /s, or 

else the NOD loading could be maintained (see 

table 1) and the flow increased to about 6,800 

ft 3 /s. 

At RM 28.6, the State DO standard is met 

by all but one of the investigated combinations 

of NOD loading and flow. The improvement 

relative to RM 55.2 results somewhat from increases in DO levels in the river, but primarily 

from the lowering of the DO standard to 6.0 

mg/L. At RM 12.0, all points of the entire 

curve set are well above the DO standard of 

5.0 mg/L. However, at RM 5.0, the position of 

the curves is lower owing to the previously described combination of carbonaceous deoxygenation, benthic demand, and decreased atmospheric reaeration. 

VARIATION OF POINT-SOURCE BODult LOADING 

AND STREAMFLOW 

Figure 9 represents predicted percent DO 

saturations at Salem flows of 5,000-8,000 ft 3 /s, 

with point-source BODua loadings of 50-200 

percent of the base condition. In this case, 

NOD loading has been held constant. As in 

Kl6 
figure 8, the base-condition point in each set of 

curves is noted by an open circle. 

Analysis of curve shapes in figure 9 shows 

that the steeper slopes occur at the downstream 

river-mile sites. This is in contrast to figure 8 

and reflects the fact that BODu1t loading has 

slight impact on DO at RM's 72.0 and 55.2, 

but thereafter an increasing impact to a maximum at RM 5.0. Also in figure 9, the vertical 

distance between curves is considerable within 

each set indicating that streamflow has a 

marked impact on DO at all locations. The 

third shape factor is the relative lack of coneshaped outlines for the five sets of curves. This 

reflects a lower degree of interactive effect of 

the two factors on DO than that occurring between NOD and flow (fig. 8). RM's 28.6, 12.0, 

and 5.0 exhibit moderately cone-shaped outlines, thus indicating that flow and BODuit 

loading do interact to a considerable degree in 

the Newberg Pool (RM 52.0-26.5) and the 

Tidal Reach (RM 26.5-0). The cause of the interaction results from effects on the same intermediate factors noted in the discussion of NOD 

and flow. 

In relation to DO standards, the critical 

sites in figure 9 are RM's 55.2 (set II) and 5.0 

(set V). As previously noted, the condition at 

RM 55.2 is dominated by flow and NOD. In 

contrast, DO levels at RM 5.0 are affected by 

upstream nitrification, the benthic demand, 

flow, and the loading of BODuit· With regard 

to the last two factors, curve set V (fig. 9) 

indicates there is a considerable safety factor 

between the base condition and the State DO 

standard. In fact, the standard at RM 5.0 would 

still be met at a flow of 5,000 fti!/s with up to 

a 20 percent increase in the point-source loading of BODuit· 

VARIATION OF POINT-SOURCE NOD AND 

BODult LOADINGS 

Figure 10 shows predicted percent DO saturations representing point-source NOD loadings of 33-150 percent of base conditions, together with point-source BODuit loadings of 

50-200 percent. For this figure, flow has been 

held constant at 6,000 ft 3 /s. 

Analysis of curve shapes in figure 10 provides several interesting results. First, curve 

slopes are controlled by the effects of NOD 

loading and are, therefore, similar to those in 

figure 8, with the greatest impact at RM 55.2 

(set II) . Second, the vertical distance between 

curves is controlled by BODuit loading. Thus, 

the closeness of the curves at RM's 72.0 and 

55.2 is further proof of the low impact of BOD 

on DO above RM 50. In contrast, the increasing space between individual curves at RM's 

28.6, 12.0, and 5.0 is further proof of the increasing impact of BODuu loading on DO levels 

in the Newberg Pool and Portland Harbor. 

Third, the lack of cone-shaped outlines of the 

curve sets reflects the absence of interactive 

effects between the loadings of NOD and 

BODult· This result is expected because, under 

conditions observed in the Willamette River, 

nitrification and carbonaceous deoxygenation 

should proceed almost entirely as independent 

processes. 

THREE-FACTOR CONTROL CURVES 

Figures 11-15 present graphs in which the 

three factors of point-source NOD loading, 

point-source BODuit loading, and streamflow 

are each varied within the ranges previously 

described. When three factors are varied at 

once, a full figure is required to present results for each site. However, because of the 

integration of the three factors, these curves 

provide a more powerful tool for river-quality 

planning. 

EXPLANATION 

Each of figures 11-15 refers to a single location on the river, which are RM's 72.0, 55.2, 

28.6, 12.0, and 5.0 (the same sites as in figs. 

8-10). In turn, each figure is composed of four 

sets of curves, I-IV, corresponding to the four 

cited (at the top) levels of point-source BODu1t 

loading of 50, 100, 150, and 200 percent of the 

base condition. Within each curve set, there 

are four curves corresponding, from top to 

bottom, to the designated streamflows of 8,000, 

7,000, 6,000, and 5,000 fti!/s. The scale included 

below each curve set shows the level of pointsource NOD loading, with 100 percent corresponding to the base condition. 

There is only one point in each of figures 

11-15 that represents the base condition. This 

point is noted by an open circle, and is located 

Kl7 
SELECTED RIVER MILES ABOVE MOUTH 

1.--72.0 --+1 1.-- 55.2 --+1 I+-- 28.6 --+I 1.--12.0 --+1 I+-- 5.0 --+I 

100 

SET I SET II SET Ill SET IV SET V 

90 Selected percentages of point-source 

BODult loading z 

Q 

1-

<{ 

a: 

::::> 

1-

<{ 

(/) 

1-

z 

w 

u 

a: 

w 

0.. 

z 

z· 

w 

(.!) 

>- X 

0 

c 

w 

> 

....J 

0 

(/) 

(/) 

c 

80 

70 

60 

EXPLANATION 

50 

100 

150 

200 

5mgi!:._ __ 

50 ----State DO standards (variable with location) 

® DO at the base condition 

I I I I 

33 67 100 150 

I I I I 

33 67 100 150 

I I I 

33 67 100 150 

I I I I 

33 67 100 150 

I I I I 

33 67 100 150 

SELECTED PERCENTAGES OF POINT-SOURCE NOD LOADING 

FIGURE 10.-DO levels at various river-mile locations for selected combinations of point-source loadings of 

BODu, t and NOD. Flow held constant at the base condition (6,000 ft1/S). 

in set II (100 percent BODuu loadirht) of each 

figure on the second curve from the bottom 

(6,000 ft1/s) and at 100 percent NOD loading. 

Within each curve set in each figure, a downward or upward movement along a specific 

curve represents a change in NOD loading, and 

a vertical movement from one curve to another 

represents a change in flow. In contrast, movement from one set of curves to another represents a change in the loading of BODuu· 

ANALYSIS OF CCRVE SHAPES 

Curve shapes in figures 11-15 can be summarized by the following comments: 

1. The base shape of each set of curves in 

each figure is determined primarily by the degree of interaction between the effects of 

streamflow and point-source NOD loading. 

Thus, the shape of the curve sets is very similar from left to right in each figure. It is helpful to note that curve set II in each figure (100 

percent BODuu loading) is identical to the site 

counterpart in figure 8. 

2. The vertical distance between individual 

curves within a set is determined by the effect of 

flow. Differences in vertical distances between 

curves in different sets of a figure result from the 

effects of point-source BOD loading. 

3. Within each figure, the differences in 

DO levels in. moving from left to right result 

from increased loadings of BODuu· Consistent 

K18 
RIVER MILE 72.0 

SELECTED PERCENTAGES OF POINT-SOURCE ULTIMATE BOD LOADING 

I+-- 50 -----+1 1~100~1 l+--150 --+I 1+---200 ___.I 

100 I 

SET I SET II SET Ill SET IV 

Discharge, in tt3/s 

90 8000 

z 7000 

0 6000 

I- 5000 

<( 

a: 

::> 

I-

<( 80 en 

Iz 

w 

(.) 

a: 

w 

a. 

z 70 

z 

w 

(!) 

>-

X 

0 

0 60 w 

> 

....J 

0 

en 

en 

0 EXPLANATION 

50 ----State DO standard (7mg/L) 

® DO at the base condition 

40 I I I I I I I I I I I I I I 

33 67 100 150 33 67 100 150 33 67 100 150 33 67 100 150 

SELECTED PERCENTAGES OF POINT-SOURCE NOD LOADING 

FIGURE 11.-DO levels at RM 72.0 for selected combinations of Salem streamflow, point-source BOD ... t 

loading, and point-source NOD loading. 

with previous discussions, there are only slight 

changes in the curve sets in moving across 

figure 11 (RM 72.0) and figure 12 (RM 55.2). 

However, in figure 13 (RM 28.6), there is a 

significant lowering of DO levels in the left-toright progression from 50 to 200 percent pointsource BODuu loading. In figures 14 (RM 

12.0) and 15 (RM 5.0), the decreases are increasingly marked. 

USE 

To illustrate the potential use of the threefactor control curves, reference will be made to 

figure 14. This figure was selected from among 

the five because the three factors-NOD loading, BOD loading, and streamflow-all have 

a significant impact on DO at RM 12.0. In figure 14, three sets of conditions are illustrated 

for selected combinations of the three factors. 

The following items present the conditions and 

describe how to estimate the percentage of DO 

saturation: 

1. BODuu=lOO percent, flow=6,000 ft3/s, 

and NOD=125 percent: Use curve set II which 

represents 100 percent BODuit loading; find the 

K19 
RIVER MILE 55.2 

SELECTED PERCENTAGES OF POINT-SOURCE ULTIMATE BOD LOADING 

I+--50 ----+1 1+--1 00 --+1 1~150---+1 1+---200 ____.., 

100 I 

SET I SET II SET Ill SET IV 

90 

z Discharge, in tt3fs 

0 8000 

1- 7000 <( 

a: 6000 

::J 

1- 5000 

<( 80 en 

1-

z 

w 

u 

a: 

w 

Q.. 

z 70 

z 

w 

(9 

>- X 

0 

0 60 w 

> 

...J 

0 

en 

en 

0 EXPLANATION 

50 ----State DO standard (7mg/L) 

® DO at the base condition 

40 I I I I I I I I I I I I I 

33 67 100 150 33 67 100 150 33 67 100 150 33 67 100 150 

SELECTED PERCENTAGES OF POINT-SOURCE NOD LOADING 

FIGURE 12.-DO levels at RM 55.2 for selected combinations of Salem streamflow, point-source BODutt 

loading, and point-source NOD loading. 

6,000 ffl Is curve; vertically extend a straight 

edge from the 125- percent NOD loading on the 

bottom scale to the 6,000 ft=~ Is curve; from the 

intersection point, noted by the letter A, the 

DO saturation is read on the Y-axis as about 

74 percent. 

2. BODuit=75 percent, flow=6,000 ft 3 ls, 

and NOD=125 percent: Locate the 6,000 ft=1ls 

curves in both set II (100 percent BODuit) and 

set I (50 percent BODuit) ; next, locate the 125 

percent NOD loading on each curve (this step 

is identical to that required in item 1 above) ; 

the located points are identified as point A in 

set II and point B in set I ; connect points A 

and B with a straight line and locate the midpoint; this point, labeled C, is the approximate 

location of the 75 percent BODu1t loading; the 

corresponding DO saturation on the Y-axis is 

about 76 percent. 

3. BOD=100 percent, flow=6,500 ft 3 ls, 

and NOD=50 percent: Use the set II curves 

for the 100 percent BODutt; vertically extend 

a straight edge from the 50 percent NOD loading scale to intersect the 6,000 and 7,000 ft 3 ls 

K20 
RIVER MILE 28.6 

SELECTED PERCENTAGES OF POINT-SOURCE ULTIMATE BOD LOADING 

I+-- 50 ---+1 1+--1 00 ---+1 1.---150 ---+1 1+--200 __.I 

100 

90 Discharge, in tt3/s 

z 8000 0 

I- 7000 <( 

a: 

::::) 6000 I-

<( 80 V) 

I- 5000 

z 

w 

u 

a: 

w 

a.. 

z 70 

6mg/L_ 

z 

w 

(!) 

>-

X 

0 

0 60 w 

> .....J 

0 

V) 

V) 

0 EXPLANATION 

50 ----State DO standard (6mg/L) 

® DO at the base condition 

40 I I I I I I I I I I I I I I 

33 67 100 150 33 67 100 150 33 67 100 150 33 67 100 150 

SELECTED PERCENTAGES OF POINT-SOURCE NOD LOADING 

FIGURE 13.-DO levels at RM 28.6 for selected combinations of Salem streamflow, point-source BODuJt 

loading, and point-source NOD loading. 

curves; the intersection points are labeled D and 

E, respectively; estimate the mid-point of the 

new line which corresponds to the flow of 

6,500 ft'/s; the midpoint is labeled F; the corresponding DO saturation as read from the Yaxis is about 83 percent. 

Any possible combinations can be evaluated 

that occur within the investigated ranges of 

the three factors. With care, the graphical estimates will be adequate for many planning purposes, thereby avoiding the need for costly and 

time-consuming computer runs to test each new 

combination. As previously shown, the authors 

have selected data at RM's 72.0, 55.2, 28.6, 12.0, 

and 5.0 for compiling figures 11-15. Similar 

data are available for constructing graphs to 

represent any location between RM's 86.5 and 

5.0. 

However, a word of caution is needed as to 

limitations of the control curves. It must constantly be kept in mind that the curves are 

based on the assumptions that ( 1) the locations of waste outfalls will remain unchanged, 

and (2) all waste sources will receive secondK21 
RIVER MILE 12.0 

SELECTED PERCENTAGES. OF POINT-SOURCE ULTIMATE BOD LOADING 

z 

0 

~ 

<( 

a: 

:::J 

~ 

<( 

en 

~ 

z 

w 

u 

a: 

w 

a. 

z 

z 

w 

(!) 

>-

X 

0 

100 

90 

80 

70 

0 60 w 

> 

...J 

0 

en 

1~50----+1 1~100~1 

SET I SET II SET Ill SET IV 

~g/L __ _ 

~r 

0 

50 

EXPLANATION 

----State DO standard (5mg/L) 

® DO at the base condition 

AA Points A-F explained in text 

40 I I I I I I I I I I I I 

33 67 100 150 33 67 100 150 33 67 100 150 33 67 100 150 

SELECTED PERCENTAGES OF POINT-SOURCE NOD LOADING 

FIGURE 14.-DO levels at RM 12.0 for selected combinations of Salem streamflow, point-source BODutt 

loading, and point-source NOD loading. 

ary treatment. In addition, the percentages of 

increased or decreased loadings in the curves 

are applied uniformly to all point sources. In 

the event of significant deviation from these 

conditions, the curves do not apply. For example, if a new large industry with a significant waste loading should build a new outfall, 

the control curves would no longer apply. 

In such cases, the WIRQAS Model (see Supplement A of this report) can be used directly 

for incorporating new information with existing data to predict the DO impacts. Although 

this would entail extra time and cost, most of 

the necessary data would be available from the 

present study. Thus, a rerun of the model could 

be readily achieved with modest cost. 

It is the hope of the authors that practical 

use will be made of both the curves in this 

report and the WIRQAS DO Model. 

SUMMARY AND CONCLUSIONS 

Future achievement of DO standards in the 

Willamette River will require continued augK22 
RIVER MILE 5.0 

SELECTED PERCENTAGES OF POINT-SOURCE ULTIMATE BOD LOADING 

1+--50---+1 1+-100---t>l l+--150---+1 1+--200__.1 

100 

90 SET I SET II SET Ill SET IV 

z 

0 

1-

<( 

a: 

::J 

1-

<( 80 en 

1-

z 

w 

u 

a: 

w 

c.. 

z 70 

z 

w 

(!) 

> X 

0 

0 60 w ------ ~giL __ 

> ...J 

0 

en 

en 

0 EXPLANATION 

50 ----State DO standard (5mg/L) 

® DO at the base condition 

40 I I I I I I I I I I I I I I I 

33 67 100 150 33 67 100 150 33 67 100 150 33 67 100 150 

SELECTED PERCENTAGES OF POINT-SOURCE NOD LOADING 

FIGURE 15.-DO levels at RM 5.0 for selected combinations of Salem streamflow, point-source BODult 

loading, and point-source NOD loading. 

mentation of summer low flows in addition to 

pollution control. At present (1979), minimum 

summer flows in excess of 6,000 fV/s (Salem 

gage) are needed to meet the standards at all 

locations below Salem. 

Point-source loading of ammonia is the 

major cause of oxygen depletion in the modeled 

segment of river (RM 86.5-5.0). Because most 

of the ammonia comes from one industrial 

source, reduction of ammonia loading offers a 

relatively simple alternative for achieving a 

large improvement in summertime DO. 

Although DO levels in Portland Harbor are 

currently above the State standard, removal or 

partial reduction of a localized benthic demand 

would improve summer DO concentrations between RM's 10 and 5. However, the feasibility 

of reducing the demand has yet to be determined. 

BOD loading from municipal waste-water 

treatment plants presently exerts a relatively 

small impact on DO. However, increased efficiency of BOD removal at the largest municipal plants and at selected industrial plants 

K23 
might be desirable in the future. The benefits 

to be gained from this alternative would best 

be determined after the industrial ammonia 

loading has been reduced to a lower level. 

For the foreseeable future, there is no need 

for municipal advanced waste treatment to 

protect DO levels in the Willamette River. 

Maintenance of a minimum low flow of 6,000 

ft 3/s and reduction of industrial ammonia 

loading are the important management needs. 

ACKNOWLEDGMENTS 

The authors want to acknowledge the aid 

and encouragement of the Non-Federal Advisory Committee on Water Data for Public 

Use. Our special thanks go to the members of 

the Advisory Committee's Ad Hoc Working 

Group on River-Quality Assessment. During 

the study, the group included Howard B. 

Brown, Robert A. Canham, Edward J. Cleary, 

Laurence R. Jahn, John E. Kinney, Walter A. 

Lyon, John A. Roller, and Clarence J. Velz. 

Clarence V elz was also instrumental in the 

design and conduct of the DO study and his 

insights were invaluable in writing this report. 

REFERENCES 

Gleeson, G. W., 1972, The return of a river in the Willamette River, Oregon: Advisory Comm. on. Environmental Sci. and Technology and Water Resources Inst., Oregon State Univ., Corvallis, 103 p. 

Hines, W. G., McKenzie, S. W., Rickert, D. A., and 

Rinella, F. A., 1977, Dissolved-oxygen regimen of 

the Willamette River, Oregon, under conditions of 

basinwide secondary treatment: U.S. Geol. Survey 

Circ. 715-I, 52 p. 

McKenzie, S. W., Hines, W. G., Rickert, D. A., and 

Rinella, F. A., 1979, Steady-state dissolved-oxygen 

model of the Willamette River, Oregon: U.S. Geol. 

Survey Circ. 715-J, 28 p. 

Oregon Department of Environmental Quality, 1975, 

Water quality control in Oregon-A status report: 

Oregon Dept. Environmental Quality Rept., 68 p. 

Rickert, D. A., Hines, W. G., and McKenzie, S. W., 

1975, Planning implications of dissolved-oxygen 

depletion in the Willamette River, Oregon, in William Whipple, Jr., ed., Urbanization and water 

quality control: Minneapolis, American Water Resources Assoc., p. 70-84. 

Rickert, D. A., Petersen, Richard, McKenzie, S. W., 

Hines, W. G., and Wille, S. A., 1977, Algal conditions and the potential for future algal problems 

in the Willamette River, Oreg.: U.S. Geol. Survey 

Circ. 715-G, 39 p. 

Shearman, J. 0., 1976, Reservoir system model for the 

Willamette River basin, Oregon: U.S. Geological 

Survey Circular 715-H, 22 p. 

Velz, C. J., 1951, Report on natural purification capacities, Willamette River: Natl. Council for Stream 

Improvement of the Pulp, Pap.er, and Paperboard 

Industries, Inc.: Michigan Univ., School of Public 

Health, Ann Arbor, 80 p. 

--- 1961, Supplementary report on lower Willamette 

River waste assimilation capacity: N atl. Council 

for Stream Improvement of the Pulp, Pap.er, and 

Paperboard Industries, Inc.: Michigan Univ., 

School of Public Health, Ann Arbor, 28 p. 

--- 1970, Applied stream sanitation: New York, 

John Wiley & Sons, Inc., 619 p. 

Wezernak, C. T., and Gannon, J. J., 1967, Oxygen-nitrogen relationships in autotrophic nitrification: Appiied Microbiology, v. 15, no. 5, p. 1211-1215. 

K24 
SUPPLEMENTAL INFORMATION 

SUPPLEMENT A-SUMMARY OF THE 

CHARACTERISTICS AND APPLICATION 

RANGES OF THE WIRQAS DO MODEL 

Based on results presented in Circulars 715-

I and J, the WIRQAS Model is considered to 

be a reliable simulatory and predictive tool, 

subject to the following conditions and limitations: 

1. Location. The model is presently 

( 1979) calibrated and verified' for the main 

stem Willamette River between RM's 86.5 to 

5.0. 

2. Ecological conditions. The model is applicable to summer, steady state conditions. 

Use is for prediction of average daily DO concentrations during low-flow, high-temperature 

conditions that have been preceded by at least 

5, and preferably, 10 days of relatively stable 

streamflow and water temperature. Such conditions annually occur in the Willamette and 

represent the most critical periods for long 

range, water-quality planning. 

3. Streamflow: 

a. Applicable range--5,000-8,000 ft 3 /s. 

This range is based on measured data from 

5,900-6,800 ft 3 /s and detailed knowledge of the 

morphology and self-purification processes of 

the Willamette River. Furthermore, the model 

can probably be used at flows up to 10,000 

ft 3 /s without the introduction of large errors. 

b. Routing. In computing discharge 

below RM 86.5, the inflows from tributaries 

and waste-water outfalls are added to flow in 

the main stem to produce a cumulative total 

at any site. Water losses due to evaporation 

and diversions are assumed to be equalized by 

ground-water seepage and inflows of small, unmeasured tributaries. 

4. Water temperature. The estimated applicable range is ±3°C of the following 1974 

low-flow measurements: RM 86.5-52.6 = 20°C, 

RM 52.6-45.0 = 21 oc, RM 45.0-37.0 = 22°C, RM 

37.0-25.6=23°C, below RM 25.6=23.5°C. 

5. Channel geometry. The model is applicable at morphologic conditions not markedly 

different from those occurring during 1973-

1974. For example, isolated dredging or filling 

would probably not cause significant differences. In contrast, a 5-ft deepening of the Portland Harbor would probably invalidate predictions made by the present model and necessitate the collection of new channel-geometry 

data in that segment. 

6. Waste loadings: 

a. Applicable character. Predominantly effluents from secondary biological treatment 

and contributions from NPS's. 

b. Model parameters : 

( 1) Carbonaceous deoxygenation. 

Simulated with first-order decay kinetics with 

the following rate coefficients kl' (20°C): (a) 

RM 86.5-55.2, k,.=0.06/d, (b) RM 55.2-5.0, 

k,.= 0.03/d. For kr at temperatures other than 

20°C, the adjustment formula was kr= k2ooc 

X 1.047l'l'-2ouC) • 

(2) Nitrification. Simulated with 

first-order decay kinetics. Significant oxygendemanding nitrification was found to occur 

only in the shallow surface-active segment, RM 

86.5-55.2. The effective rate of nitrification 

(k 11 ) calculated from the rate of appearance of 

nitrate-N = 0.7 /d. No temperature adjustment 

was necessary because summertime water temperatures in the affected river segment are 

very close to 20°C. 

(3) Benthic-oxygen demand. Simulated as an oxygen-demanding load distributed between RM 12.8 to 5.2. The total load 

was estimated to be 29,000 lb/ d (table 4). As 

discussed in Circular 715-I, only -part of this 

demand is thought to result from "in-place" 

benthic-oxygen demand. The remainder probably results from several additional causes. 

7. Algal photosynthesis and respiration. 

DO produced and consumed by algae were 

taken to be in balance over the 81.5-mi modeled 

stretch of river. Between RM's 86.5 and 13, 

this assumption is supported by primary production data and by DO mass balance computations made with preliminary versions of the 

model. However, between RM's 13 and 5, algal 

respiration may, in fact, exceed photosynthetic oxygen production (see "Benthic Oxygen 

Demand Impact" section under "Planning Implications" in this report and also Rickert and 

others, 1977). 

8. Atmospheric reaeration. Calculated on 

a segment-by-segment basis using the Velz 

(1970) method. The additional reaeration at 

Willamette Falls (RM 26.5) is simulated by 

K27 
adding 13,400 lb/d of DO to profile computations. This addition is consistent with measurements made above and below the Falls during 

1974 low-flow conditions. 

SUPPLEMENT BMODEL BOUNDARY POINT (RM 86.5) 

WASTE LOADINGS FOR SELECTED 

STREAMFLOWS 

Computation of DO profiles over the selected 

range of stream flows (fig. 6) required use of 

assumptions for calculating the boundary point 

waste input loadings. The need for assumptions 

resulted because no loading measurements have 

been made across the entire range of selected 

flows. This supplement describes how the 

model input loadings were determined fo:r both 

the point and NPS components of BODu1t and 

NOD. 

POINT-SOURCE BODu1 t LOADING 

Point source loadings of BODuit at RM 86.5 

were calculated by direct flow routing of each 

source and, thus, involved no major assumptions. To accomplish the flow routing, the timeof-travel from the source to RM 86.5 was determined from existing information. Next, the 

measured summertime BODuit load from each 

source was decayed at a temperature-corrected 

rate (based on k,.=0.06/d at 20°C) for the determined travel time. Finally, the residuals of 

each source at RM 86.5 were summed to provide the model input loading. The same procedure was followed for each investigated flow. 

NPS BODul t LOADING 

Determination of the NPS BODuit loading at 

RM 86.5 was based on the assumption that for 

conditions represented by the flow range of 

5,000-10,000 ft 3 /s at Salem, the NPS loading 

of individual upstream tributaries is effectively 

constant. The assumption is based on observation that (1) in-river BODu1t concentrations in 

major tributaries above point-source discharges are very low (approximating natural 

background levels), (2) the major tributaries 

are shallow with bottoms that produce significant amounts of biological materials, and (3) 

during summer low-flow conditions, precipitation is usually nil or very low for an extended 

periorl of time and, hence, little or no overland 

flow enters upstream tributaries or the main 

stem of the Willamette. 

For summer, low-flow conditions, the rationales behind the assumption are ( 1) the NPS 

BODuit loading in major upstream tributaries 

is mostly stream generated, (2) the amount 

generated depends on the total surface area 

of stream bottoms covered by water, and (3) 

that the total surface areas of individual 

stream bottoms do not change appreciably for 

tributary flows which represent cumulative 

Salem flows in the range of 5,000-10,000 ft 3 /s. 

The rationales are consistent with measured 

data and field observations, and they support 

the occurrence of a condition in which constant 

tributary loads of NPS BODuit would be produced. 

On the basis of the stated assumption, NPS 

BODuu loads at measured points in tributaries 

were individually flow routed to RM 86.5 at 

determined times of travel. As with the pointsource routing, the rate of decay was a 

temperature-corrected coefficient based on kr 

= 0.06/ d at 20°C. 

As noted above, actual loading data at RM 

86.5 were collected over the Salem flow range 

of 5,900-6,800 fP/s. For the latter streamflow, 

the total flow-routed load (point plus NPS) at 

RM 86.5 was checked against the measured instream load. The values were almost identical 

(see fig. 4 in Circular 715-J). 

It might be expected that the contribution of 

reservoir water to the low flows of major tributaries would exert a controlling influence on 

the loading of NPS BODuu at RM 86.5. However, distances from reservoir discharge points 

to measurement locations are deemed sufficient 

to permit stream-bottom biology to damp any 

small differences in NPS BODuit loadings 

(from above to below a reservoir) that might 

occur as a result of reservoir influences. 

Between the flows of 5,000 and 10,000 fV /s, 

it is possible that the described assumption 

would not hold at the higher flows, such as 

those above 8,000 fP /s. If this were so, the 

probable direction of -failure would be an increased loading with flow owing to (1) increased contribution of nonbase-flow water and 

(2) increased scour of in-stream growths. This 

deviation from the assumption at the higher 

K28 
flows would result in lessened impacts of reservoir low-flow augmentation than those predicted. In other words, in figure 6, the DO profile predicted for 10,000 ft 3 /s might show 

higher DO levels than those that would actually 

occur. 

Analysis of stream morphologies and field 

observations in the shallow reaches above RM 

50 suggests that the assumption would not hold 

at a flow of 3,260 ft 3 /s (see figs. 6 and 7). The 

WIRQAS Model can be confidently applied 

down to 5,000 ft 3 /s and possibly to 4,000 ft 3 /s. 

However, at severe drought flows, the channel 

conditions, other physical factors, and several 

self-purification characteristics in the reach 

above RM 50 are thought to differ considerably 

from those existing at flows between 5,000 and 

10,000 ft 3 /s. Factors that probably change significantly include stream widths, water temperatures, sedimentation rates, and the opportunity for renewed contact between flowing 

water and the bottom growths. However, for 

lack of a better method, the BODu1t loading at 

RM 86.5 for the flow of 3,260 fV/s (figs. 6 and 

7) was computed in a manner similar to all 

other curves. Therefore, as noted in the text 

(see "Impact of Low-Flow Augmentation"), 

the resulting curves at 3,260 ft'/s are viewed 

as estimates of the DO levels that would actually occur. 

POINT AND NPS NOD LOADINGS 

Flow routing could not be used to determine 

NOD loadings at RM 86.5 because no ammoniaN decay data were measured on the upper 

Willamette River and the upstream tributaries. 

The approach used was based on measurements which showed an ammonia-N concentratration of 0.16 mg/L at RM 86.5 during the 

1974 calibration studies (flow=6,760 ft 3 /s). 

Prior to and during this period, measured concentrations of ammonia-N in major upstream 

tributaries (above point sources) averaged 

about 0.04 mg/L. In the absence of decay rates 

to permit routing, the assumption was made 

that 0.04 mg/L of the measured 0.16 mg/L at 

RM 86.5 represented an NPS contribution, 

whereas the remaining 0.12 mg/L was a pointsource contribution. 

POINT-SOURCE NOD LOADING 

For the different discharge levels used in the 

control runs, point-source NOD loading at RM 

86.5 was kept constant at the level computed 

for the calibration period (NOD= 18,900 lb/d). 

It might be reasoned that point-source NOD 

reaching RM 86.5 would vary in some direct 

manner with flow because, the higher the flow, 

the shorter the time of travel for ammonia decay. However, it is also possible that the rate 

of decay would increase with flow because the 

nitrification process occurs on the stream bottom and higher flows would increase the possibility of water-column turnover. In the absence 

of measured kn rates, and because the two cited 

cases would counter one another, the choice 

was made to hold the point-source NOD loading constant across the investigated range of 

flows. 

NPS NOD LOADING 

The NPS NOD loading at different flows 

was computed on the assumption that the concentration of NPS ammonia-N remains constant at RM 86.5. The assumption, in turn, is 

based on 1974 summer, low-flow measurements 

of ammonia-N at sites above known point 

sources on the Middle Fork, McKenzie, and 

Santiam Rivers. Three to six samples were 

analyzed from each river. Individual concentrations varied somewhat from sample to 

sample, but, as previously noted, the average 

was about 0.04 mg/L for each river. Because 

these three tributaries contribute over 95 percent of the Willamette River summer flow at 

RM 86.5, the level of 0.04 mg/L was accepted 

as a reasonable background and, therefore, 

NPS concentration of ammonia-N at the model 

boundary point. 

It is interesting to note that an average 

ammonia-N concentration of 0.03 mg/L was 

measured in the Clackamas River which drains 

the Cascade Range and enters the Willamette 

at RM 24.8. The controls that cause background ammonia-N levels of 0.03-0.04 mg/L 

are unknown, but the concentration does appear to be representative of regional, base-flow 

conditions. 

Based on the stated assumption (NPS NOD 

concentration is constant), the NPS NOD 

loading at RM 86.5 was determined by multiplying the 0.04 mg/L concentration by the discharge selected for each predicted curve. At 

flows of 8,000-10,000 ft 3 /s, the possibility 

K29 
exists that the NPS ammonia-N concentration 

would be lower than 0.04 mg/L. This possibility is based on the consideration that 0.04 

mg/L represents the regional base-flow concentration in the range of 6,000-7,000 ft 3 /s. If 

this were true, our calculated input loads of 

ammonia-N at RM 86.5 would be too high at 

the higher flows. This w0uld mean that actual 

DO profiles would be slightly higher than predicted by the control curves. 

SUPPLEMENT CDECAY RATES FOR COMPUTING 

CARBONACEOUS OXYGEN DEMANDS 

Carbonaceous oxygen demands in this report 

were computed assuming that all point and 

NPS BODuit decays in the river at kr=0.06/d 

above RM 55.2, and at 0.03/ d below this location. Circular 715-I describes how these two 

rates were determined through a combination 

of measurement and preliminary runs of the 

WIRQAS Model. 

The assumption that point and NPS BODuu 

loads decay at the same rate is backed by the 

following reasoning. First, measured bottle 

BOD rates (k,) for both municipal and industrial discharges to the Willamette River are 

low and in the same range as rates for tributary waters collected above all known point 

sources (Circular 715-I, table 5). Second, it 

would be expected that the oxidative character 

of organic materials from well-treated (highly 

oxidized) secondary effluents should approximate the oxidative character of organic matter 

in natural streams. Thus, the bottle rate data 

are consistent with intuitive reasoning that the 

natural organic matter of streams and the organics in well-treated secondary effluents 

should both be well on the way to biochemical 

stabilization. 

1:r U.S. GOVERNMENT PRINTING OFFICE: 1980 0- 311-344193 

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