Project Development and Data Programs for 

Assessing the Quality of the 

Willamette River, Oregon 

By David A. Rickert, Walter G. Hines, 

and Stuart W. McKenzie 

RIVER-QUALITY ASSESSMENT OF THE WILLAMETTE RIVER BASIN, OREGON 

G E 0 L 0 G I CAL SURVEY CIRCULAR 715-C 

1976 
United States Department of the Interior 

THOMAS S. KLEPPE, Secretary 

Geological Survey 

V. E. McKelvey, Director 

Rickert. David A. 1940-

Project development and data programs for assessing the quality of the Willamette River, 

Oregon. (River-quality assessment of the Willamette River Basin. Oregon) 

(Geological Survey Circular 715-C) 

Bibliography: p. 30-31. 

1. Water quality-Oregon-Willamette River. I. Hines, Walter G., joint author. II. 

McKenzie, Stuart W .. joint author. III. Title. IV. Series. V. Series: United 

States Geological Survey Circular 715-C. 

QE75.C5 no. 715-C[TD224.07] 363.6'1 76-608207 

Free on application to Branch of Distribution, U.S. Geological Survey, 120 0 South Eads Street, Arlington, VA 2 2 2 0 2 
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 theN ation'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: Willamette River as it winds through Portland, Oregon. Photograph taken by 

Hugh Ackroyd. 
CONTENTS 

Page 

1\bstract -------------------------------------------- C1 

Introduction __ ____ ___ _ ____ _ _ ____ __ _ ___ __ _ _ ________ _ _ 1 

The Willamette River basin __________________________ 2 

Project framework ---------------------------------- 4 

Duration ______ ______________ ______________ ______ 4 

~anpower -------------------------------------- 4 

Project elements ------------------------------------ 4 

Identified river-quality problems__________________ 4 

Nonpoint-source pollution ____________________ 4 

Reservoir-release quality ____________________ 5 

Dissolved-oxygen depletion __________________ 5 

1\lgal-problem potential ______________________ 6 

Trace-metal occurrence ______________________ 6 

Sanitary quality ---------------------------- 7 

1\ccelerated erosion -------------------------- 7 

Riverbank esthetics__________________________ 7 

Selection of project elements______________________ 8 

River hydrology______________________________________ 8 

Hydrologic analysis------------------------------ 8 

Flow---------------------------------------- 8 

Water temperature _________________ ________ 8 

Channel morphology ________________________ 11 

Upstream Reach ________________________ 11 

"Newberg Pool"-------------------------- 11 

Tidal Reach ---------------------------- 11 

Hydrologic modeling ---------------------------- 11 

Reservoir-simulation model __________________ 13 

Tidal-reach hydraulic model__________________ 15 

The approach for obtaining appropriate data __________ 15 

Matching methods and data programs to assess selected 

problems-------------------------------------- 16 

Dissolved-oxygen deletion ________________________ 16 

The method-mathematical modeling ________ 16 

Model configuration ______________________ 16 

Critical period __________________________ 17 

Calibration and verification ______________ 17 

Data program ------------------------------ 18 

Deficiencies of monitoring and surveillance 

data ---------------------------------- 18 

Role of existing data ____________________ 18 

Matching methods and data programs to assess Page 

selected problems--Continued 

Dissolved -oxygen deletion-Continued 

Data program-Continued 

Premodeling reconnaissance ______________ C19 

Data program for calibration and verification ---------------------------------- 19 

Rationale for the data program __________ 20 

Impact ofland-use activity on erosion and river qual- 20 

ity ---------------------------------------- 20 

The method-interpretive mapping____________ 20 

Basis____________________________________ 22 

Presenting the results____________________ 22 

Data program ------------------------------ 23 

False-color-IR photography ______________ 23 

Photomosaic base________________________ 23 

Terrain property data____________________ 23 

Climate ---------------------------- 24 

Slope________________________________ 24 

(}eology ---------------------------- 24 

Soils ___ _ __ __ __ _ _ ______ __ ________ ____ 24 

Runoff------------------------------ 24 

Comparative roles of existing and new data 

Potential for algal problems ______________________ 24 

Infeasibility of mathematical modeling________ 24 

The method-descriptive assessment __________ 25 

Data program ------------------------------ 25 

Role of existing data ____________________ 25 

Reconnaissance__________________________ 26 

Intensive studies ________________________ 26 

Rationale for the data program __________ 26 

Trace-metal occurrence __________________________ 26 

The method-descriptive assessment __________ 26 

Sampling medium ______________________ 27 

Distinction between natural background 

and pollution __________________________ 27 

Data program ------------------------------ 27 

Rationale for the data program ______________ 28 

Summary and conclusions---------------------------- 28 

Acknowledgments____________________________________ 29 

References ------------------------------------------ 30 

ILLUSTRATIONS 

Page 

FIGURE 1. Map of the Willamette River basin emphasizing main stem, tributaries, and reservoirs ____________________ C3 

2. (}raphs showing Willamette River discharge at Salem, Oreg .. 1944, 1964, and 1973 water years____________ 9 

3. (}raphs showing mean monthly and maximum and minimum daily temperatures for three sites on the North 

Santiam, Willamette, and South Yamhill Rivers, Oreg. ---------------------------------------------- 10 

4. Map and diagram representing the Willamette River, Oreg., showing distinctive hydrologic reaches, and elevation profile________________________________________________________________________________________ 12 

v 
Page 

FIGURE 5. Graphs showing typical channel cross sections of the Willamette River, Oreg., at concurrent low-flow conditions ------------------------------------------------------------------------------------------- C13 

6. Schematic showing the lower Willamette River system ------------------------------------------------- 14 

7. Schematic showing the process of assessing the impacts of land-use activity on erosion and river quality___ 21 

TABLES 

Page 

TABLE 1. Existing or potential river-quality problems: Willamette River basin, Oreg. ------------------------------ C5 

2. Selected information for major reservoirs in the Willamette River basin, Oreg. ---------------------------- 10 

3. Selected physical characteristics of the main stem Willamette River, Oreg.-------------------------------- 12 

CONVERSION FACTORS 

[Factors for converting English umts to the Internatwnal System of Units lSI 1 are given below to four significant figures. However, 

in the text the metric equivalents are shown only to the number of significant figures consistent with the values for the English 

units] 

English 

ft (feet! 

ft/s (feet per second! 

ft/mi (feet per mile l 

ft/acre (feet per acre) 

ft3/s (cubic feet per second! 

acres 

acre-ft (acre-feet l 

mi (miles) 

mi 2 (square miles! 

Multiplv by 

3.048x 10-1 

3.048x 10-1 

1.894 X 10- 1 

7.532x 10- 1 

2.832x10-2 

4.047x1o- 1 

1.233x 10-3 

1.609 

2.590 

VI 

Metric lSll 

m (metres) 

m/s !metres per second) 

m!km (metres per kilometre) 

m/hm2 (metres per square hectometre) 

m3/s (cubic metres per second) 

hm2 (square hectometres) 

hm3 (cubic hectometresl 

km (kilometres l 

km2 (square kilometres) 
Project Development and Data Programs for 

Assessing the Quality of the Willamette River, Oregon 

By David A. Rickert, Walter G. Hines, 

and Stuart W. McKenzie 

ABSTRACT 

The U.S. Geological Survey recently (19761 completed an 

intensive river-quality assessment in the Willamette River 

basin, Oregon. The objectives were to ( 1 l define a practical 

framework for conducting comprehensive river-quality assessments; (2) determine the kinds and amounts of data required to adequately assess various types of river-quality 

problems; (3 l develop techniques for evaluating such data and 

for presenting it so as to promote better public understanding 

of its significance; (4l develop and document methods for 

evaluating basin-development alternatives in terms of potential impacts on river quality; and (5) apply the framework, 

data, and methods to assess the existing or potential riverquality problems of the Willamette River basin. 

This circular covers aspects of the five objectives by examining overall project development and the methods and data 

programs used to assess four river-quality problems. The assessed problems were ( 1) the effect of population and industrial growth and resulting waste discharges on dissolved oxygen, (2) the potentially harmful effects on land and river quality of accelerated erosion resulting from intensified land use, 

(3) the potential for nuisance algal growths, and (4) the possibility of trace-metal accumulation in river-bottom sediments. 

This circular describes the approaches and rationales used 

to organize the project, to select and formulate the assessment 

methods, and to design the data programs. The purpose is to 

provide in-depth information on project development and design as an aid and stimulus for others who are interested in 

river-quality assessment. 

INTRODUCTION 

Virtually all forms of growth and development 

exert some impact on river quality. Achievement 

of desirable river quality at acceptable cost requires that management decisions be based on 

sound impact assessments, not on arbitrary assumptions. Thus, the vital link between 

resource-development plans and management decisions is scientific assessment to predict the 

probable impacts of each planning alternative. At 

present, river-quality assessment is the Achilles' 

heel of the overall process. The difficulty in appraising impacts results from (1) the absence of a 

rational framework for structuring such work, (2) 

the lack, poor development, and misapplication of 

assessment methods, and (3) the scarcity of reliable data. 

To develop a unified approach for river-quality 

assessment the U.S. Geological Survey recently 

conducted a prototype study of the W illamette 

River basin, Oregon. The objectives were to ( 1) 

define a practical framework for conducting comprehensive river-quality assessments; (2) determine the kinds and amounts of data required to 

adequately assess various types of river-quality 

problems; (3) develop techniques for evaluating 

such data and for presenting it so as to promote 

better public understanding of its significance; (4) 

develop and document methods for evaluating 

basin-development alternatives in terms of potential impacts on river quality; and (5) apply the 

framework, data, and methods to assess the most 

important existing or potential river-quality 

problems of the Willamette River basin. 

To meet the first objective, the initial circular of 

this series (Rickert and Hines, 1975) presented a 

seven-step practical framework for conducting 

comprehensive river-quality assessments. The 

present circular covers aspects of all five objectives by examining overall project development 

and the methods and data programs used to assess four river-quality problems. The specific 

problems were (1) the effect of population and industrial growth and resulting waste discharges 

on dissolved oxygen (DO), (2) the potentially 

harmful effects on land and river quality of accelC1 
erated erosion resulting from intensified land use, 

(3) the potential for nuisance algal growths, and 

( 4) the possibility of trace-metal accumulation in 

river-bottom sediments. The goal of the assessment program, and thus the context of the 

methods and data programs, was to provide technically sound, appropriate, and adequate information for land-use and water-resource planning. 

This circular is based on an unpublished work 

plan and includes information and knowledge developed during the first 2 years of the study. The 

various sections describe the approaches and 

rationales used to organize the project, select and 

formulate the assessment methods, and design 

the data programs. 

The information is intended for use by both the 

scientific and planning communities. The data 

programs may be of particular interest to State 

and regional resource-planning agencies as a 

basis for designing in-house programs to assess 

specific problems, and for evaluating the suitability of programs proposed by Federal agencies and 

consulting firms. The approach and method sections should be useful to specialists in the 

environmental-science community who are interested in becoming involved in interdisciplinary, problem-solving programs. All the information should have high transfer value to other 

studies, because the problems being assessed in 

the Willamette are common to many of the Nation's rivers. 

THE WILLAMETTE RIVER BASIN 

The Willamette River basin, a watershed of 

nearly 11,500 mi2 (29,800 km2) (fig. 1), is located 

in northwestern Oregon between the Cascade and 

Coast Ranges. Within the basin are the State's 

three largest cities, Portland, Salem, and Eugene, 

and approximately 1.4 million people, representing 70 percent of the State's population (1970 census). The basin supports an economy based on 

timber, agriculture, industry, and recreation, and 

contains extensive fish and wildlife habitats. 

The Willamette River basin is roughly rectangular, with a north-south length of about 150 mi 

(240 km) and an east-west width of 75 mi (120 

kmL Altitudes vary from less than 10 ft (3 m) 

near the mouth of the Willamette River, to 450ft 

(140 m) on the valley floor near Eugene, and to 

more than 10,000 ft (3,050 m) in the Cascade 

Range. The Coast Range generally varies in average altitude from 1,000 to 2,000 ft (300-600 m) 

but includes peaks higher than 4,000 ft (1,200 m). 

The slopes and foothills of the Cascade Range 

account for more than 60 percent of the basin 

area. About 62 percent of the basin is timberland 

located largely in the tributary basins (Gleeson, 

1972). Approximately 33 percent of the area is 

farmland, and the remaining 5 percent is urbanized and in other uses. 

The main stem Willamette River forms at the 

confluence of the Coast and Middle Forks south of 

Eugene and flows northward for 187 mi (301 km) 

through the 3,500 mi2 (9,100 km2) Willamette 

Valley floor. The first 135 mi (217 km) of the river 

is characterized by a meandering channel. 

Through most of the remaining 52 mi (84 km), the 

Willamette flows within well-defined banks, unhindered by falls or rapids except for the basaltic 

intrusion at Oregon City which creates the Willamette Falls. The 26.5 mi (42.6 km) reach below 

the falls is subject to nonsaline tidal effects, 

transmitted from the Pacific via the Columbia 

River. The Willamette empties into the Columbia 

at a point which is 99 mi (160 km) from the Pacific 

Ocean. 

Historically, the Willamette River experienced 

acute water-quality problems related primarily to 

summer low-flow and heavy organic-waste loading from cities and pulp and paper mills. In recent 

years, low-flow augmentation from storage reservoirs and the basinwide advent of secondary 

wastewater treatment have markedly improved 

the quality of the river. However, in light of 

expected urban and industrial growth, decisionmakers are now involved with evaluating alternatives for keeping future river-quality conditions at the present high levels. 

The W illamette River basin was selected for 

the prototype study for several reasons. First, 

there was an excellent base of background data, 

particularly on hydrology. Second, the social and 

political attitudes in Oregon reflected a keen 

interest in environmental quality. This suggested 

that the people and agencies would welcome the 

study and that results would be used at the State 

and local levels. Third, a river-basin management 

plan already existed, as did several land-use projections (Willamette Basin Task Force, Main Report, 1969). Thus, the study could evaluate existC2 
r-

(f) 

<( 

0 

u 

INDEX MAP OF OREGON 

FIGURE 1. 

0 

I I 0 10 

-Willamette River . basin, Oregon. 

C3 

10 

I 

20 MILES I io KILOMETRES 
ing planning alternatives to provide a realistic 

test of assessment approaches. Fourth, the Willamette was the largest river in the Nation on 

which all major point-source discharges received 

secondary waste-water treatment (Oregon Department of Environmental Quality, 1970). The 

quality was above the stringent State standards, 

and the river was considered a national success 

story (Gleeson, 1972). Thus, the study would be 

able to appraise the factors to which past improvement was attributed while evaluating the 

management options for maintaining or improving the quality. 

PROJECT FRAMEWORK 

DURATION 

The time required to conduct a useful assessment of river quality is a compromise between 

taking enough time to do a sound and comprehensive scientific study and so much time that results 

become irrelevant to the decisionmaking process. 

The compromise initially selected for the prototype Willamette study was 2 years, beginning 

in January 1973. The original concept was to use 

6 months for planning and for organizing field 

and laboratory programs, 12 months for collecting and analyzing data and the writing of initial 

reports, and 6 months for completing the analysis 

of data and the final reports. 

After the first 2 months it became obvious that 

assessment of certain river-quality problems 

would require extending data collection into the 

fall of the second year. Thus, it would be impossible to reduce the data collected during this time 

interval and to have it incorporated into final reports. On this basis, the study duration was expanded to 2¥2 years. 

In retrospect, 2Yz years appears to be a reasonable period for intensive, practical assessment of 

river-quality problems. This duration provides 

time for (1) identification of specific river-quality 

problems, (2) project planning prior to initiation 

of fieldwork, (3) 1 full year of fieldwork, and (4) 

the opportunity to recheck specific problems in 

the field during the most critical time period of 

the annual cycle. In many river basins (including 

the Willamette) summer is the critical time 

period for most river-quality problems. For such 

basins a study duration of 2¥2 years, together 

with a January start, provides for two summer 

field seasons. River-quality studies longer than 

2%-3 years begin to lose their usefulness to the 

resource-planning process. Specific critical problems may require assessment over longer periods, 

but initial assessments of immediate problems 

need to be completed. As noted in a previous circular (Rickert and Hines, 1975), reappraisals can 

then be made under reduced time pressures, 

while full scale updates can be scheduled on a 

periodic basis. 

MANPOWER 

The nature of river-quality problems requires 

an interdisciplinary, team-oriented assessment. 

In the Willamette study the discipline categories 

included hydrology, sanitary chemistry, aquatic 

biology, mathematical modeling, geology, and 

air-photointerpretation. The project team was 

composed of four individuals having different professional backgrounds, together with five parttime aides. Analytical work was done by the project team and by several Geological Survey 

laboratories. In addition, the project periodically 

used the talents of the Water Resources Division's 

research staffs and District offices, as well as the 

consultative, fieldwork, and laboratory inputs of 

scientists from several universities. 

PROJECT ELEMENTS 

Specific work elements for the program were 

determined through discussions with State, interstate, and Federal agencies concerned with the 

management of river quality. The discussions 

proceeded over the first 4 months of the project to 

identify eight existing or potential river-quality 

problems. These problems were then evaluated 

using data and information from the Oregon Department of Environmental Quality (1970, and 

unpublished), the Geological Survey (1962-73, 

1964-73) and the STORET system ofthe U.S. Environmental Protection Agency (Sayers, 1971). 

Next, in conjunction with the concerned agencies, 

the problems were ranked in order of their relative importance to resource management (table 

1 ). This section briefly outlines each of the eight 

problems and provides rationales for the assigned 

rankings of importance. 

IDENTIFIED RIVER-QUALITY PROBLEMS 

NONPOINT-SOURCE POLLUTION 

Knowledge of non point sources of pollution is a 

critical information need for effective riverC4 
quality management. In the Willamette River 

basin, considerable general knowledge was available on nonpoint sources, but information was 

lacking on quantitative loadings and their effects. 

Potential nonpoint sources of concern in the 

basin included (1) land-use activities such as logging, construction, and agriculture, (2) irrigation 

return flow, (3) urban runoff, (4) navigation, (5) 

gravel and navigational dredging, and (6) benthal 

oxygen-demanding deposits in Portland Harbor. 

Of these six items, existing concern over the 

sediment problems arising from intensive land 

use caused this topic to be listed as a separate 

problem in table 1. In addition, possible benthal 

deposits in Portland Harbor were considered 

under the problem category of DO depletion. In 

contrast, navigation, together with gravel and 

navigational dredging, were only of minor concern to planners as potential sources of pollution. 

The remaining two items were irrigation and 

urban runoff. Nearly half a million acres 

(2.0x 105 hm2) are irrigated in the basin, and 

water volumes average about 2.3 feet of water per 

acre (1.7 m/hm2) per season. However, irrigation 

is almost exclusively by sprinkler and therefore, 

involves practically no surface runoff. Hence, 

there is virtually no transport of suspended or 

dissolved solids to the river from this activity and 

no detectable impact on river quality. 

On a yearly basis, urban runoff undoubtedly 

washes large tonnages of contaminants into the 

Willamette River system. However, the summers 

are extremely dry in the Willamette River basin, 

and nearly all the annual precipitation occurs 

during the months of October through March. 

Moreoever, the winter and spring rains tend to be 

continuous and gentle, rather than intense. These 

patterns suggest that most of the oxygendemanding materials and nutrients that enter 

the Willamette from urban runoff are probably 

washed from the river prior to the low-flow, highTABLE 1.-E.-risting or potential river-quality problems: 

Willamette River basin, Oreg. 

Relafzpe 

temperature summer period when biological 

river-quality problems are most likely to occur. 

Concern was voiced over the possibility that 

urban runoff and other sources might be causing 

a buildup of toxic metals in the Willamette. However, this information need was already covered 

under the problem category of trace-metal occurrence. 

Following numerous discussions, it was decided 

that those aspects of non point sources not covered 

under other topics were relatively unimportant to 

assessment of major river-quality problems in the 

Willamette. Accordingly, the category was assigned a relative importance of 3. 

RESER VOIR-RELEASE QUALITY 

Reservoir releases represent potential point 

sources of pollution to any river system. Early 

discussion with planning officials indicated concern that reservoir releases could possibly affect 

the turbidity, temperature, and nutrient content 

of the Willamette River. The concern existed 

primarily because water is sometimes released 

from lower levels of certain reservoirs instead of 

from the surface. Such water would be low in 

temperature and possibly high in turbidity and 

nutrient concentrations. 

Existing records from various sources were 

analyzed to determine possible impacts of reservoir releases on the quality of the Willamette. 

The data indicated that the reservoirs do not contribute any significant long-term turbidity to the 

river. Similarly, although cool-water releases do 

occur, the tributary streams quickly warm to ambient water temperatures because of rapid mixing 

resulting from steep gradients and high turbulence. Water temperatures in the main stem of 

the Willamette apparently are only slightly affected by releases of cold reservoir water. 

Problem zmportance* 

Existing records did show spring and fall upsurges of phosphorus concentrations in the Willamette. Such upsurges are consistent with a 

pattern of reservoir turnover and known release 

patterns. This problem needed attention but 

was included under the problem category of 

algal-problem potential. The category of reservoir-release quality was consequently ranked as a 

priority 3 item. 

Nonpoint-source pollution ______________________ 3 

Reservoir-release quality________________________ 3 

Dissolved-oxygen depletion______________________ 1 

Algal-problem potential ________________________ 2 

Trace-metal occurrence__________________________ 1 

Sanitary quality-------------------------------- 3 

Accelerated erosion __ _ _ ___ _ ____ __ _ ____ _ _ _ ____ _ _ 1 

Riverbank esthetics ____________________________ 2 

*1 = greatest Importance; 3 = least importance. 

C5 

DISSOLVED-OXYGEN DEPLETION 

Historically, maintenance of high DO content 
has been the critical problem in the Willamette 

River. During summer low-flow periods, the DO 

content in Portland Harbor often went to 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 (Rickert, Hines, and 

McKenzie, 1976l. The improvement has resulted 

from a reduction in the loading of biochemical 

oxygen demand (BOD), coupled with streamflow 

augmentation from storage reservoirs. However, 

the Oregon Department of Environmental Quality (DEQ) still considers the maintenance of high 

DO levels to be the factor of highest priority in 

planning the Willamette's future. At the time of 

the study, long-range planning was especially 

timely, because DEQ anticipated (Oregon Department of Environmental Quality, 1970) that 

DO conditions would peak in 1972 with the application of secondary treatment to all major municipal and industrial wastes. Because of the immense importance of DO to long-range planning, 

the problem was given a number 1 priority. 

ALGAL-PROBLE11 POTENTIAL 

In the Willamette River, a potential for excessive algal growth may exist because nitrogen and 

phosphorus loadings are increasing, whereas carbon loading (measured as BOD) is decreasing 

(Gleeson, 1972). The decrease in carbon loading 

has resulted from the application of secondary 

treatment to all major sources of organic wastes. 

The nitrogen and phosphorus levels remain high 

because both nutrients are ineffectively removed 

by standard secondary treatment and because 

nitrogen is present in very high concentrations in 

certain industrial wastes. 

Despite the high nitrogen and phosphorus concentrations in the Willamette, excessive growths 

of algae have not been observed. The reason 

might be any one of several including trace-metal 

limitations, unfavorable water temperatures, 

high summertime turbidities, or short, water 

detention times. On the other hand, the environment in the Willamette could possibly be approaching a condition in which large, problemcausing growths of algae might begin to occur. 

Recent work in the Upper Potomac Estuary 

suggests that the initiation of secondary treatment may cause ecological shifts in receiving 

waters and actually stimulate the growth of nuisance blue-green algae (Jaworski, Lear, and 

Villa, 1971). Concern about preventing future 

algal problems in the Willamette resulted in this 

problem category receiving a priority 2 ranking. 

TRACE-METAL OCCURRENCE 

Many materials discharged into river systems 

are toxic to aquatic organisms when present in 

critical concentrations. These materials include 

numerous trace metals and manmade organic 

compounds such as insecticides, polychlorinated 

biphenyls (PCB's), herbicides, and certain industrial organics. Even though such materials are 

usually discharged to rivers at subtoxic levels, 

many are capable of being concentrated at successive steps in aquatic-food chains in a process 

called "biological magnification." 

An approach for evaluating sublethal toxicity 

conditions is badly needed for the purpose of 

long-range river-basin planning. However, research is just beginning to relate the characteristics of biological communities to the contents of 

toxic materials in water, sediment, and aquaticfood chains. The work began only recently because scientists previously lacked the techniques 

to accurately determine low levels of the metals 

and organics. Now, the major problem is how to 

sample the environment so the results are reliable. This will take many years to resolve and 

will involve studying the life cycles of many 

aquatic organisms to determine when and how 

specific ones can be used as toxicity indicators. 

In lieu of definitive studies, it is useful to develop background information on the levels of 

toxic materials in river water, bottom sediments, 

and aquatic organisms. Review of industrialdischarge records in the Willamette Basin indicates that there 1s little possibility of toxic industrial organics entering the Willamette River. 

Furthermore, over the past 10 years, "hard" (persistent) pesticides have not been used in the basin 

for disease vector control nor for widespread 

plant-pest control. 

In contrast, there are several industrial sources 

of potentially toxic trace metals in addition to the 

metals that undoubtedly enter the river in urban 

runoff. Thus, if a toxicity problem occurred, it 

would probably result from accumulation of trace 

metals. Existing records provided no data on the 

distribution of trace metals in the Willamette 

River system. Such information was needed for a 

C6 
comprehensive evaluation of river quality and, 

accordingly, an assessment of trace-metal occurence was assigned a relative importance of 1. 

SANITARY QUALITY 

Coliform bacteria levels in the Willamette 

River exceed the State standard of 1,000 organisms per 100 ml over most of the annual cycle. 

This occurs in spite of high levels of waste-water 

treatment and the disinfection of all treatmentplant effluents. Median coliform counts range 

mostly from 2,500 to 3,500 during summer, lowflow conditions, but the numbers increase at high 

flows. 

The Oregon DEQ (Oregon Department of Environmental Quality, 1970) has identified two 

major sources of enteric bacteria in addition to 

waste-water treatment plants. One is rapid 

bacterial growth in organic solutions from certain 

industrial effluents. The other is land runoff, 

especially urban and agricultural storm drainage. The fact that coliform counts increase with 

flow indicates that land runoff has a major influence on bacterial populations. DEQ notes that coliforms from both of these major sources are 

mostly nonfecal and, presumably, should have little if any, public-health significance. Although 

sanitary quality in the Willamette requires 

further study, the problem was given a number 3 

priority because of the apparent nonfecal origin of 

the bacterial populations. 

ACCELERATED EROSION 

Projections for the Willamette Valley indicate a 

great increase in population and industry over 

the next 50 years. Large acreages of land now in 

forest or agr~cultural use will be urbanized. In 

addition, vast areas of forest land will be logged 

for Oregon's pulp and paper industries. At present, the potential impact of these activities on 

land and river quality is virtually unknown. 

What is known is that the Willamette at high 

flow is very turbid and that man's activities, such 

as logging, construction, and agriculture, are 

primarily responsible (Willamette Basin Task 

Force, Appendix G, 1969). The economic costs include dredging (especially Portland Harbor) for 

navigation, increased costs of treating water 

supplies, and the loss of spawning and feeding 

areas for fish. In addition, man's activities in the 

basin sometimes trigger large-scale land deformations such as landslides, slumps, and gullies. 

Such deformations often ruin the land for further 

intended use and result in large costs for cleanup 

and restoration. The deformations also release 

additional quantities of sediment to tributary 

streams and thus eventually to the main stem. 

The situation in the Willamette is now such 

that either land-use activity and land runoff are 

brought into the planning picture or else the ultimate reality may be land-imposed constraints 

on river quality. An integrated assessment is 

needed of how different uses of land and water 

may affect the quality of these resources. The first 

requirement for this type of assessment is a 

method for delineating the erosional impacts associated with different land-use activities on different types of terrain. The critical nature of this 

problem resulted in a priority ranking of 1. 

RIVERBANK ESTHETICS 

Oregon is presently engaged in a Greenway 

Plan to protect open space along the Willamette 

and to give the residents of the valley access to 

the water and wildlife. The Greenway was originally conceived as a continuous parkland along 

both banks of the river. However, realities of 

funding, legislation, and land-use needs have 

changed the concept to a more modest proposal for 

a series of intermittent parks (Council on Environmental Quality, 1973). The question therefore arises of how to determine which parcels of 

land are most suitable for inclusion in the 

Greenway system. Although such decisions require the balancing of numerous factors, one 

prominent factor is riverbank esthetics. The visual impact of the river and related landscapes 

largely determines the value of land as open 

space and the enjoyment that people receive from 

its use. 

Thus, delineation of riverbank esthetics is 

presently a prominent problem of the Willamette 

River. To determine the value of land as open 

space, a system is needed to evaluate the factors 

that contribute to landscape esthetics. Leopold 

(1969) has devised a system which first identifies 

relevant landscape features that influence esthetic impression and then uses these features to rank 

the relative uniqueness of different sites. A ranking of sites based on this or a similar system could 

be done for the Willamette. Because of the need, 

the category was assigned a relative importance 

of2. 

C7 
SELECTION OF PROJ~CT ELEMENTS 

The selection of project elements was completed 

by analyzing the priority list (table 1) in terms of 

ability to produce useful information within the 

boundaries of time, funding, and manpower. All 

three priority 1 problems were selected as project 

elements, whereas the three priority 3 problems 

were rejected. Both priority 2 items were considered for inclusion over a period of several months, 

but, finally, on the basis of available manpower, 

algal-problem potential was included and riverbank esthetics was rejected. 

In summary, the four project elements were as 

follows: 

1. Dissolved-oxygen depletion 

2. Impact of land-use activity on erosion and 

river quality 

3. Potential for algal problems 

4. Trace-metal occurrence 

The next task of project development was to 

define and analyze those major hydrologic factors 

that influence the four selected problems. With 

the exception of land-related analyses for the erosional element, the hydrologic analyses were 

focused on the main stem of the Willamette, beginning at Eugene. Tributaries were treated primarily as inputs to the main stem. 

RIVER HYDROLOGY 

Hydrologic characteristics determine the physical dynamics of rivers, which, in turn, control the 

occurrence and extent of chemical and biological 

processes (Velz, 1970; Hines, Rickert and McKenzie, 1976). Because of this control, analysis of 

river hydrology is a prerequisite to selecting a 

method or identifying the data needed to assess a 

river-quality problem. Only through such 

analysis can we understand the inherent 

(background) variability in river quality that results from natural variations in hydrology. Once 

this understanding is attained, the impacts of 

man on the basin can be examined independently 

of natural variations. 

Thorough analysis of existing hydrologic data 

was the first technical step of the Willamette 

study. Data from several sources (U.S. Geological 

Survey, 1962--73; Willamette Basin Task Force, 

Appendix B, 1969; Velz, 1951, 1961) were collated 

and then analyzed to provide a basis for designing 

the data-collection programs needed to assess the 

four project elements. 

HYDROLOGIC ANALYSIS 

FLOW 

Most of the flow in the Willamette occurs in the 

period November to March as a result of persistent winter rainstorms and spring snowmelt. 

Post-March snowmelt in the high Cascade Range 

often prolongs seasonal runoff into June or early 

July. These patterns of flow are illustrated by the 

hydrographs in figure 2. The 1944 hydrograph is 

typical of natural runoff patterns prior to largescale reservoir regulation (considered to be pre1953), whereas the 1964 and 1973 hydrographs 

reflect postregulation patterns. Three reservoirs 

began operation on tributaries in the Coast 

Range and Calapooya Mountains (see fig. 1.) in 

the period between 1941 and 1949. However, it 

was not until operation of reservoirs on Cascade 

Range tributaries, beginning in water year 1954, 

that reservoirs had a significant impact on Willamette River flow. Table 2 summarizes information on the major Willamette Basin reservoirs, 

including the initial dates of flow regulation. 

Reservoir regulation has had a profound impact 

on low flows in the W illamette (Hines, Rickert, 

and McKenzie, 1976). Marked increases have occurred in the 1-, 3-, 7-, 14-, and 30-day low flows 

during the post-1952 period. Reservoir regulation 

has also tended to curtail the length of the period 

of low flow, typically from about mid-July 

through mid-October before regulation, to about 

mid-July through mid- or late-August following 

regulation. This condition occurs because the reservoirs, as recently operated, release extra water 

in the early fall to enhance anadromous fish runs. 

WATER TEMPERATURE 

As typified in figure 3, streams and rivers 

draining the Cascade Range have cooler temperatures than those draining the Coast Range. The 

large Cascade tributaries, the McKenzie, Santiam, and Clackamas Rivers, are cool because 

they originate at high altitude where springs and 

snowmelt contribute to the flow and where air 

temperatures are cooler than in the Coast Range 

or on the valley floor. The Cascade Range 

tributaries also have larger volumes of flow which 

tend to maintain the cooler temperatures 

downstream. 

Water temperatures in the Willamette and all 

major tributaries reach a maximum during the 

July-August period that coincides with the onset 

CB 
100,000 

1000 

10,000 

100 

1000 

0 

z 0 100,000 0 z u 0 w 

u (/} 

w a: (/} w cr: c.. 

w 1000 (/} 

c.. w 

1- a: w 1-

w w l.l. ~ 

u ~ Q) 10,000 Q) 

::::> ::::> 

u u 

~ ~ w· w· <.9 <.9 a: 100 a: <1: <1: :r: I u u (/} (/} 

0 0 

1000 

100,000 

1000 

10,000 

100 

FIGURE 2.-Willamette River discharge at Salem, Oreg., 1944, 1964, and 1973 

water years. 

of low-flow conditions. The coincident occurrence 

of high temperature and low flow make the 

July-August period the most critical with regard 

to river-quality conditions, particularly DO 

levels. 

Spatial patterns of water temperatures in the 

C9 
TABLE 2.-Selected information for major reservoirs in the Willamette River basin, Oreg. 

Total 

usable Dramage Date ReservOir 

lsee fig. 1 1 

capanty area regulation 

Tributary stream 

Fern Ridge __________ _ Long Tom River------------------------- ___________ _ Cottage Grove __ Coast Fork Willamette River_______ _ ___________ _ 

Dorena ___________________ _ 

Hills Creek _______________ _ Row River ltnbutarv to WIIIamettel ____________________ _ Middle Fork Willaniette _______________________________ _ 

Lookout Point! ______________ _ Mtddle Fork Willamette _____ -------------------------------- Fall Creek __________________ _ Cougar _________________ _ Fall Creek !tributary to Middle Fork Willamettel South Fork McKenzie ____________________ _ 

Blue River 

Green Peter _ 

Blue RIVer ltnbutarv to McKenzie I ____________________________ _ 

Middle Santtam ___ · _____________________ _ 

Foster ____________ _ South Santiam _____________________________________________ _ 

Detroit2 __________ _ ____ North Santiam ______________ _ 

'Dexter Reservoir, a small reregulatmg reservoir, IS located just downstream. 2Big Chff Reservoir, a small reregulating reservoir. is located just downstream. 

North Santiam River at Niagara 

Willamette River 

at Salem 

lacre-ft 1 

110.000 

30.100 

70.500 

249,000 

349.000 

115,000 

165,000 

85.000 

333,000 

33,200 

340,000 

1.879.800 

Maximum 

25 

(I) 

:::> 

Cii 

...J 

w 

(.) 20 Cl) 

w 

w 

a: 

(!) 

w 

c 

~ 15 

w· 

a: 

::> 

1-

<( 

a: 10 w 

0.. 

::E 

w 

1-

5 

0 

JFMAMJJASOND JFMAMJJASOND 

lmi2 1 

252 

104 

265 

389 

911 

184 

208 

88 

277 

494 

438 

South VamhHt River 

near Willamina 

JFMAMJJASON 

FIGURE 3.-Mean monthly and maximum and minimum daily water temperatures for the North Santiam, Willamette, and South Yamhill Rivers, Oreg. 

began 

11/41 

10/42 

10/49 

8/61 

11/53 

1/66 

9/63 

10/68 

10/66 

12/66 

1153 

Willamette have been analyzed by the Willamette Basin Task Force (Appendix B, 1969). For the 

July-August period, the results indicate that 

water temperatures increase in the downstream 

direction. The results suggest that reservoir regulation has only a slight impact on the temperature regimen of the Willamette. The subreach 

above Albany (see fig. 1) often has lower temperatures than would be expected because of the influence of cool, bottom-release waters from the 

Lookout Point-Dexter Reservoir complex on the 

Middle Fork (see table 2). However, reservoirs on 

the other tributaries are apparently far enough 

upstream to allow cold release waters to reach 

ambient temperature before confluence with the 

Willamette. 

C10 
CHANNEL MORPHOLOGY 

The Willamette River is composed of three distinctive reaches whose morphologic characteristics partly govern both the hydraulics of flow and 

river-quality behavior. Pertinent data for each of 

the three reaches are included in figures 4 and 5 

and in table 3. 

UPSTREAM REACH 

The Upstream Reach, stretching for 135 mi 

(21 7 km) from Eugene to above Newberg, is 

characterized by a meandering channel. The river 

is shallow (table 3), and the bed is composed almost entirely of cobbles and gravel which, during 

summer, are covered with biological growth. 

Although the U.S. Army Corps of Engineers 

has straightened the course of this reach considerably, there are still numerous meanders, islands, and side channels. At low flow, gravel bars 

are visible, and, in some places, the river is so 

shallow that small pleasure boats occasionally 

run aground. 

During the low-flow conditions, average stream 

velocity in the Upstream Reach is seven times 

that of either of the two downstream reaches (table 3). During floods, velocities are sufficiently 

high to transport large quantities of cobbles and 

gravel as bedload. Morphologically this upstream 

section of the Willamette is an ((eroding" reach. 

"'NEWBERG POOL" 

The HN ewberg Pool" extends from just above 

Newberg down to Willamette Falls, a distance of 

25.5 mi (41.1 km). The pool is deep (fig. 5), slow 

moving, and hydraulically can be characterized 

as a large stilling basin behind a weir (Willamette Falls). As evidenced by the elevation 

profile (fig. 4), low velocity, and the presence of 

fine bottom sediments, the pool is a depositional 

reach. 

Comparison of time-of-travel data (table 3) 

with those compiled by Velz (1951) suggest that 

dredging and gravel mining during the last 25 

years have significantly increased low-flow 

travel times in the pool (about 30 percent at 7,000 

ft3Js or 198 m3/s). 

During summer, most of the flow that reaches 

Willamette Falls is diverted through powergeneration turbines or over a fish ladder. These 

diversion activities can cause mild fluctuations in 

water levels and flow velocities throughout the 

entire length of the pool. 

TIDAL REACH 

The Tidal Reach, covering the lower 26.5 mi 

(42.6 km) of the river, is affected by tides and, 

during spring and early summer, by backwater 

from the Columbia River (Velz, 1961). The Tidal 

Reach is extensively dredged to maintain a 40-

foot (12 m) deep navigation channel (fig. 5) from 

the mouth to about RM 14. The subreach between 

RM's 5 and 14 is a busy shipping corridor known 

locally as '(Portland Harbor." 

During low flows, net downstream movement is 

relatively slow in this reach, but tidal effects 

cause flow reversals twice daily and large 

changes in velocity. Low-flow hydraulics are most 

complex in the lower 10 mi (16 km) (fig. 6) where, 

depending on hourly changes in tide and river 

stage, Willamette River water may move downstream or Columbia River water may move upstream. The Columbia River water has a slightly 

higher concentration of dissolved solids and is 

commonly several degrees cooler than Willamette 

water. Columbia water is, therefore, denser than 

Willamette water and, during part of each day 

(during low flows), moves upstream as a distinct 

bottom wedge to the vicinity of the St. Johns 

Bridge (RM 6). The subsequent downstream 

movement of mixed water is very complex. Depending on slight variations in tide and flows in 

the two rivers, the downstream discharge may be 

out the mouth of the Willamette, through 

Multnomah Channel (see fig. 6), or a combination 

of the two. 

Owing to morphological characteristics and 

hydraulic conditions, the subreach between RM's 

10 and 3 is the primary depositional area of the 

Willamette River system. 

HYDROLOGIC MODELING 

Collation of existing hydrologic data was the 

necessary first step for designing the data programs needed to assess the quality of the Willamette River. The collated basic data were also 

used to help analyze the collated river-quality 

data, to assess the impacts of alternative resource 

plans, and to format the final reports. However, 

additional hydrologic information was needed to 

adequately assess the impact of planning alternatives on future river quality. The most critical 

needs were information on (1) future low-flow 

quantities and frequencies and (2) the character 

of flow and velocities in the hydraulically complex 

lower 10 mi ( 16 km) of the river. These needs 

C11 
(A) 

\ 

s 

( 3 135 mi (217 km) 

187 (301 km) 

( 

\ 

0 30 MILES 

I I '• I 

0 50 KM 

(B) 

FEET 

~ ~+-~-~~~~~::~~-----------------U--PS_T_R--EAM __ R_E_A_C_H------------~rW:~~~~~ 

200 100 I '=t=t=t=t=~~~~~~~=F=F=t=f=f=f~~=r=r-r-r-.-,-,-.rl~~O:O~L~~ REACH 

METRES 

160 

120 

80 

40 

LE~~~ . ._~~~~~~~-,-s~o~~~~_L~~~~~,-o~o_L_L_L~~~~~~~s~o~~~~~--~~._~~or~~EL 

300 

Reach 

(see fig. 41 

Tidal Reach (1). 

Newberg Pool (21. 

Upstream Reach (3). 

DISTANCE, IN RIVER MILES ABOVE MOUTH 

200 100 

DISTANCE, IN RIVER KILOMETRES ABOV~ MOUTH 

FIGURE 4.-Willamette River, Oreg., A, Distinctive hydrologic reaches. B, Elevation profile. 

TABLE 3.-Selected physical characteristics of the main stem Willamette River, Oreg. 

[Characteristics refer to summer low-flow conditions of 6x 103 ft3 /s at Salemi 

Representative 

Approximate midchannel Average 

Length bed slope water depth velocity !mil fft/mil Bed material rftl rft/sl 

26.5 <0.1 Intermixed clay, sand, and gravel. 40 10.16 

25.5 .12 Intermixed clay, sand, and gravel with some cobbles. 25 10.40 

135 2.8 Mostly cobbles and gravel. 7 2 2.9 

'Calculated by volume displacement method using channel cross-sectional data. 2Calculated from dye study by Geologi:al Survey rHarris, 19681. 

0 

Approximate 

traveltime 

in reach 

(days) 

10.0 

3.9 

2.8 

required the development of predictive mathe-1 data inputs are briefly outlined in the following 

matical models. The modeling approaches and the two sections. 

C12 
River mile 119 (Upstream Reach) River mile 40.8 (Newberg Pool) 0 \, __ ,_/'" r--r--------------------------r-~ 0 

10 

1- 5 en 

w w 

w 20 0: 

1- 1.1.. w 

Discharge= 5280 ft

3

/s 

(150m%) 

~ 

:£ 

1- 30 Q.. 

w 

0 

~ 

z 

r.· 

1-

6100 tt% 10 Q.. 

Discharge= w 

(173m%) 

0 

40 

50 15 

River mile 9.2 (Tidal Reach) 

10 

5 

'?0 en 

w 1-

w 

w 

1.1.. 

0: 

1-

w 

~ 

z 30 z 

r.' 

1-

Q.. 

w 

0 40 

10 r.' 

1-

Q.. 

w 

0 

15 

0 200 400 600 800 FEET 

0 100 200 METRES 

FIGURE 5.-Typical channel cross sections of the Willamette River, Oreg., at concurrent low-flow conditions. The large 

downstream increases in width and depth greatly affect the hydraulics of flow and, thereby, partly determine the 

reach-by-reach potential for different types of river-quality problems. 

RESERVOIR SIMULATION MODEL 

As noted in table 2, there are 11 major reservoirs in the Willamette River basin with a combined usable capacity of nearly 1.9 million acre .. ft 

(2300 hm3). The reservoirs are designed for multipurpose use, but their primary legal function is 

the maintenance of a minimum navigable depth 

in the Willamette. The required minimum flow 

for navigation is 6,000 ft3fs (170 m3/s), Salem 

gage. Other uses of the reservoirs and reservoir 

water include power generation, onsite recreation, flood protection, maintenance of adequate 

streamflow for anadromous fish propagation, irriC13 
River mile 3.3 

(channel bifurcation) ----"ai 

River mile 6.0 

(St. Johns Bridge) 

1 

N 

I 

45° 30' 

0 5 MILES 

I 1

1 

I I 1 • ,

1 

0 8 KILOMETRES 

FIGURE 6.-Lower Willamette River system. During low-flow conditions at fl.oodtide, Columbia River water commonly 

moves upstream beyond St. Johns Bridge as a distinct bottom wedge of denser water. Depending on slight variations in tides and river flows, the subsequent discharge of mixed Columbia-Willamette water may be out the mouth 

of the Willamette, through Multnomah Channel, or a combination of the two. 

gation, and flow augmentation for water-quality 

enhancement. The latter use is not explicitly 

planned but occurs as a result of summertime releases made for the other purposes. 

The objective of the reservoir simulation model 

was to provide estimates of the future low-flow 

magnitudes and frequencies in the Willamette as 

a basis for assessing alternative plans for riverC14 
quality managenient (Sherman, 1976). Specifically, the model was developed to help answer 

three important questions: 

1. What role has past flow augmentation 

played in bringing the Willamette to its present 

good quality? 

2. What is the predicted magnitude-frequency 

relationship of summer flows under present 

reservoir-operating procedures and river-water 

diversions? 

3. What is the predicted magnitude-frequency 

relationship of summer flows for the next 50 years 

under present reservoir-operating procedures and 

anticipated river-water diversions? 

The model could also be used to assess the impact on low flow of alternative procedures for reservoir operation and, in addition, to assess the 

effect of potential new reservoirs. 

The HEC-3 computer program of the U.S. 

Army Corps of Engineers (1968) was selected for 

the modeling task. This model performs multireservoir routings based on flow requirements 

at various contrOl points throughout the river 

system, while rrlaintaining a specified storage 

balance among the reservoirs. Because low-flow 

statistics at Salem reveal a strong relationship 

between 7- and 30-day low flows, it was decided to 

simulate reservoir operations on a monthly basis. 

Monthly values are adequate for long-range 

planning, and the use of monthly rather than 

daily flows greatly reduced the complexity and 

cost of modeling. 

Data required to verify and use the model 

included information on unregulated flow; regulated flow; reservoir evaporation; and past, present, and future diversions. The approach for obtaining time sequences of unregulated flows was 

to correlate flows measured prior to regulation at 

each reservoir inflow station with flows at stations that have remained unregulated. The calculated relationships were used to estimate what 

reservoir inflows would have been under unregulated conditions up through 1973. Evaporation 

data for the model were estimated from a previously developed relation between evaporation 

and mean monthly temperature. Diversion data 

were scarce and represented the weakest link in 

the model. 

TIDAL-REACH HYDRAULIC l\'IODEL 

Before river quality could be assessed quantitatively in Portland Harbor, the hydraulic characteristics of the tidally affected lower 26.5 mi (42.6 

km) of the Willamette (see fig. 6) needed to be 

defined. A hydraulic model of the lower river was 

developed to provide this definition (Bennett, 

1975). 

Inputs to the model included the channel 

geometry of the Tidal Reach and Multnomah 

Channel, time histories of stage at the outfalls of 

the Willamette River and M ultnomah Channel 

on the Columbia, and discharge at two locations 

in the Willamette River and at one location in 

Multnomah Channel. 

Data collection for model calibration involved 

synchronized water-surface elevation monitoring 

over 4- to 5-day periods at several points on the 

Willamette, the Columbia, and in Multnomah 

Channel. Data were collected at four different 

combinations of flow conditions in the Willamette 

and Columbia Rivers (for example, high Willamette flow, low Columbia flow; low Willamette 

flow, high Columbia flow). Verification was based 

on the ability of the model to predict flow velocity 

and depth during four different 12.5-hour tidal 

cycles as measured at the two stations on the Willamette and the one station in Multnomah Channel. 

The model outputs are velocity and depth of 

flow at any point in the Tidal Reach and 

Multnomah Channel. The model is dynamic because velocity and depth can be simulated for any 

assumed conditions of tide and discharge in the 

Columbia and Willamette Rivers. 

THE APPROACH FOR OBTAINING 

APPROPRIATE DATA 

Valid data are a fundamental necessity for 

sound resource assessment. The kinds and 

amounts of data required to assess a river-quality 

problem depend primarily on the complexity of 

the problem, the areal extent of study, and the 

nature of the method chosen for assessment. 

In the Willamette study, the data required to 

assess the four priority problems (see ~~Selection 

of Project Elements") were obtained through a 

four-step approach: 

1. Identify the types of data required to assess 

each problem. 

2. Collate and analyze pertinent existing data. 

Where these data appear insufficient to assess the problem adequately, proceed to step 

3. 

3. Design a reconnaissance study to determine 

C15 
the following: 

a. The major factors that actually affect the 

river-quality problem in question. 

b. The anticipated range of values for each 

factor. 

c. The amount of data needed to analyze each 

cause-effect relationship. 

4. On the basis of steps 1 through 3, design and 

implement a field and laboratory datacollection program at an intensity appropriate to adequately assess the problem. 

This approach is both comprehensive and flexible. It directs a delineation of data needs, the full 

use of existing data and, where necessary, the development of a carefully designed program for collection of new data. 

MATCHING METHODS AND 

DATA PROGRAMS 

TO ASSESS SELECTED PROBLEMS 

The remainder of this paper examines the four 

previously described river-quality problems in 

terms of the methods chosen to assess each problem and the approaches used to identify, collect, 

and collate the required data. The discussion focuses on (1) the criteria for selecting and applying 

the assessment methods and (2) the development 

of each data program. The detail of presentation 

is provided to enable readers to follow the stepby-step development of functional rationales. The 

order of presentation is designed to contrast the 

three methods of assessment and the four data 

programs. 

DISSOLVED-OXYGEN DEPLETION 

THE METHOD-MATHEMATICAL MODELING 

Mathematical modeling provides a potential to 

quantify the cause-effect relationships that give 

rise to DO problems. The potential exists because 

(1) a sound theoretical and empirical basis exists 

for writing the necessary equations, (2) the data 

required for calibrating and verifying a practical 

and reliable model can be collected, and (3) proven techniques are available for analyzing raw 

data to obtain model coefficients. Mathematical 

models are usually preferable to other methods of 

studying DO problems because they are capable 

of providing the most quantitative analysis of 

critical relationships. They, therefore, represent 

the best available approach for predicting the 

possible impacts on DO of alternatives for future 

river-basin development. The predictive ability is 

essential because, at present (1976), DO is the 

most important parameter for managing quality 

in the majority of the Nation's rivers. 

In concept, mathematical modeling of DO provides a powerful tool for problem solving to resource planners and managers, pollution-control 

officers, and governmental decisionmakers. However, with notable exceptions, these groups have 

failed to accept DO models as practical planning 

tools and have viewed river-quality models with 

considerable mistrust. This failure to accept and 

trust models may stem from the fact that some 

river-quality models have not been based on sufficient data nor effectively applied to real planning 

and management situations. Similar conclusions 

have been cited by other investigators, including 

Lombardo (1973); Weber, Kisiel, and Duckstein 

(1973); and Velz (1970). 

This section will describe considerations vital 

to the formulation and use of a practical DO 

model for the Willamette River (see Hines, Rickert, McKenzie, and Bennett, 1975). 

MODEL CONFIGURATION 

General applicability to any river is sometimes 

an important objective of a DO model. Usually, 

models with this objective are sophisticated in 

configuration because they must have dynamic 

mathematical components and model parameters 

for simulating the common deoxygenation and 

reaeration phenomena, plus photosynthesis, nitrification, and benthal oxygen demand. In addition, the model must account for extreme ranges 

in river discharge, hydraulic conditions, river 

temperature, and other environmental factors. 

The resulting sophisticated model configuration 

seldom is justified by environmental conditions or 

planning and management needs in any particular basin. 

The essence of applied DO modeling is to fit the 

model to the river rather than the river to the 

model. This was done for the Willamette River by 

making a premodeling reconnaissance to determine the most reasonable level of model sophistication. The reconnaissance was designed to provide preliminary information on mixing 

phenomena, waste-loading characteristics, riverflow patterns, expected ranges of model parameter values, and the presence or absence of nitrification and benthal oxygen-demanding deposits. 

Insight into such factors prior to formulation of 

C16 
the model greatly enhanced the compatability of 

the model with conditions actually occurring in 

the river. 

CRITICAL PERIOD 

The size and complexity of most river basins 

limit the capability for modeling all seasonal 

changes of the DO regimen. There is a mystique, 

perhaps fostered by reliance on general-case 

models, that because seasonal changes in DO occur, a useful model must simulate all these 

changes. In reality, attempts to formulate such 

models may obscure important objectives, waste 

money and time, and provide useless results. 

In many river basins there is a critical seasonal 

period, controlled by cyclic hydrologic processes, 

at which a DO model can be aimed. In the Willamette River basin, planning and management 

decisions have been (and are being) predicated 

almost entirely on stressed DO conditions that 

occur only during the low-flow, high-temperature 

summer period. Thus, for planning and management purposes, a DO model of the Willamette 

needs to simulate only those conditions that occur 

during a 2- to 3-month period. 

The critical-period rationale for modeling DO 

in the Willamette offered several advantages. 

First, the critical conditions occur during hydrologic periods of steady-state flow. This means 

there was no practical need for dynamic-model 

components. Steady-state, plug (nondispersive) 

flow was realistically assumed, and only small 

ranges in associated variables and processes 

needed to be considered. Second, the critical lowflow conditions are a function of basin hydrology, 

as modified by reservoir-release schedules, and 

recur on a cyclical basis. Thus, it was possible to 

evaluate recurrence probabilities of discharge 

levels (see ttReservoir-Simulation Model") and to 

relate these to predictions from the DO model. 

Third, data needs for calibration and verification 

of the model were greatly reduced. Because only a 

short period of the year needed to be studied, the 

field program was intensive enough to provide a 

high degree of data reliability. 

CALIBRATION AND VERIFICATION 

Calibration is the procedure whereby model 

parameters are adjusted so that model outputs 

(for a particular set of input data such as streamflow, temperature, and waste loads) approximate 

a set of observed river-quality data. The ranges 

within which parameters can be realistically adjusted are important to the credibility and utility 

of the model. 

Modelers are often faced with poor data for 

calibration and, as a consequence, rely heavily on 

mathematical-optimization techniques to quantify model parameters. The optimization process 

involves two steps. First, a numerical range is 

established within which each model parameter 

can vary. The range, which is typically quite 

large, is usually obtained from a literature review. Second, numerous computer runs are made, 

and values for each parameter are simultaneously varied within the established ranges. During the computer runs, a least-squares procedure 

is used to obtain a t'best fit" of model outputs to a 

set of observed river-quality data. The modelparameter values resulting in the ttbest fit" are 

considered to be the optimum values. Often these 

values are not checked independently for realism 

within the actual river system. 

When done in the described manner, calibration becomes a computerized ttcurve fitting" process instead of a ttfine tuning" process governed by 

scientific understanding and direct river experience. Unless the computed values happen to be 

closely similar to actual values in the river, the 

resultant model will be incapable of reliably predicting future river-quality conditions. 

In the Willamette study, the schedule was organized so that numerical values for critical 

parameters could be established by independent 

field and laboratory study. For example, the 

range of deoxygenation rates was established by a 

carefully conducted BOD sampling and analysis 

program. Similarly, reaeration rates, though not 

directly measurable, were approximated for each 

reach through careful collation of flow and 

channel-geometry data. In addition, all major underlying assumptions (for example, homogeneous 

mixing, plug-flow) of the model were checked for 

reasonableness. 

Verification is the essential step for substantiating the predictive capability of a river-quality 

model. The procedure involves the use of a calibrated model (that is, the same model-parameter 

values developed during calibration) and a new 

set of observed data. Some of the new data establish the boundary conditions necessary to ttstart" 

and t•run" the model. The rest of the data serve as 

an independent set of observations for comparison 

with model predictions (outputs). 

C17 
If the model predictions are acceptably close to 

the independent observations, the model is considered verified. If the predictions are not acceptably close or if model-parameter values must be 

juggled to make the model ~'fit" the observations, 

the verification has failed. The acceptably close 

criterion should be established before verification 

and can, in part, be based on the ngoodness of fit" 

obtained during calibration as defined by the 

standard error of estimate (see Dawdy, 1969). 

To provide a sound planning model, the data 

used in verification must not include any data 

used to calibrate the model or to develop its 

parameters. Moreover, as noted above, the acceptably close criterion for verification should be 

established before verification. Both these needs 

were met in the Willamette DO model by the intensive collection of field data during the summers of successive years. Data from one summer 

was used for calibration, data from the other, for 

verification. 

DATA PROGRAM 

DEFICIENCIES OF MONITORING 

AND SURVEILLANCE DATA 

In many basins, the existing river-quality data 

base has been compiled largely through 

pollution-monitoring and surveillance programs. 

Such programs are usually concerned with determining compliance with State and Federal 

water-quality standards or with attempts to discern trends. Monitoring and surveillance programs usually involve routine grab sampling and 

rigid temporal and spatial guidelines. For example, in a particular river, 10 sites might be designated for sampling once or twice a month (commonly during daylight hours only on weekdays 

for temperature, DO, pH, specific conductance, 

alkalinity, turbidity, BOD, and coliform bacteria). Periodic samples may be collected for other 

selected constituents such as nitrogen and phosphorus. Continuous monitors for temperature or 

pH might also be operated at one or two sites. 

Attempts are often made to use monitoring and 

surveillance data for calibration and verification 

of applied DO models. Unfortunately, such data 

are usually poorly suited for these purposes. This 

lack of suitability stems from several factors 

(Hines, Rickert, McKenzie, and Bennett, 1975): 

1. Correlative data on hydrology and, especially, 

waste discharges are seldom determined. As 

a result, most monitoring and surveillance 

data indicate effects rather than provide insight into causes. A river-quality model can 

be structure imitating and predictive only if 

cause-effect relationships are quantitatively 

established. 

2. Monitoring programs usually collect limited 

grab samples at widely dispersed sites under 

a wide variety of conditions. Such data 

rarely provide quantitative knowledge of 

reach-to-reach, cross-sectional, and diurnal 

(dieD variations. This is particularly true for 

a nonconservative dynamic variable such as 

DO. 

3. The relationship between discharge and time 

of travel is seldom known or is overlooked in 

the planning of monitoring programs. 

Therefore, results obtained from individual 

sites represent a synoptic picture of the river 

only if samples happen to be collected during 

a long-term, steady-state flow condition and 

at the same time of day. This is rarely the 

case. 

4. The inherent sampling and analysis errors for 

river-quality variables are relatively large. 

Consequently, to develop an applied DO 

model, a number of sample sets are necessary to define an index of variability. 

ROLE OF EXISTING DATA 

In spite of the factors listed above, existing 

monitoring and surveillance data can often be 

useful for designing intensive studies of riverquality phenomena and for providing checks on 

modeling predictions. The utility of existing data 

for these purposes (assuming the appropriate variables were sampled) is determined by several 

conditions: (1) the period of record, (2) collection 

frequency, (3) location and number of sampling 

stations, and (4) the ease with which the data can 

be segregated and collated in relation to river 

hydrology. The segregation and collation are 

necessary to distinguish the effects of man from 

the natural variabilities in quality that result 

from temporal and spatial changes in hydrology. 

Analysis of existing monitoring data for the 

Willamette River did provide significant insight 

into conditions surrounding DO depletion. The 

analyses indicated (1) the general magnitude of 

DO depletion (as much as 40 percent depletion of 

DO saturation), (2) the affected reaches of the 

river (the lower 80 mi (129 km)), (3) the yearly 

period of most severe DO depletion (July-August), 

C18 
and (4) the fact that summer flow was effectively 

steady-state and greatly augmented by reservoir 

releases. This information provided the 

background for development of a reconnaissancelevel study. 

PREMODELING RECONNAISSANCE 

The reconnaissance-level study was made to 

determine (1) river mixing and flow patterns, (2) 

waste-loading characteristics, (3) preliminary information on the presence or absence of nitrification and benthic oxygen-demanding deposits, and 

(4) expected ranges of model-parameter values. 

Results of the survey indicated that several 

major changes had occurred since 1951 and 1960 

when Velz (1951, 1961) studied the DO regimen 

of the Willamette: BOD loadings were much 

lower and more uniform because of basinwide 

secondary treatment; river deoxygenation rates 

were much lower; large benthal deposits were absent except in Portland Harbor; and riverchannel geometry, and thus detention time and 

reaeration rates, had been affected by dredging. 

Conversely, one important condition remained 

unchanged: The river was still well mixed in most 

reaches. The preliminary results also indicated 

that nitrification was not significant, but the data 

were collected in the spring before the onset of 

high-temperature conditions. Subsequent data 

collected during July and August showed that 

nitrification was a dominant factor in the summertime DO regimen. 

The findings of the reconnaissance indicated 

that a simpler model configuration could be used 

than was originally anticipated. The results also 

provided a sound basis for the design and implementation of an efficient data-collection program for calibration and verification. 

DATA PROGRAM FOR CALIBRATION AND VERIFICATION 

The goals of the intensive data-collection program were (1) establishment of cause-effect relationships for each process that affects DO and (2) 

independent evaluation and quantification of 

each model parameter and assumption. The resultant program included eight major elements as 

follows: 

1. General hydrologic characteristics of the river 

were determined (table 3) and compared 

with existing DO records. As expected, the 

deep, slow-moving Tidal Reach and ''Newberg Pool" (see fig. 4) exhibited significant 

summertime depletion of DO. In addition, 

the shallow, swift-flowing Upstream Reach 

showed significant DO depletion beginning 

in the vicinity of Salem. Above Salem, projected pollutional loadings and the physical 

characteristics of the river (high velocities, 

geometry indicative of rapid reaeration) 

suggested that DO depletion would not become a problem in the foreseeable future. 

Accordingly, only the lower part of the river 

beginning near Salem was studied in a 

manner intensive enough to provide a suitable data base for DO modeling. 

Selection of field-sampling stations was 

based on ( 1) locations of waste discharges 

and tributaries, (2) locations of stream 

gages, (3) information on river mixing (obtained in the reconnaissance study), (4) 

times of travel, and (5) availability of boatlanding sites. Nearly all sampling was done 

from boats to avoid the possible influences 

on flow and local river quality that might 

result from bridges or other in-stream structures. 

2. Each modeling reach was studied intensively 

for 2- or 3-day periods during the JulyAugust steady-state, low-flow periods of 

1973 (see fig. 2) and 1974. During each 

study, 5 to 10 stations were sampled in each 

reach from dawn until dusk. Every 2 hours, 

DO and water temperature were measured 

using a meter and field probe, and where 

warranted by indications within the sections, horizontal and vertical traverses were 

made. River BOD samples were collected 

every 2-4 hours. Samples to determine BOD 

loading were collected daily or at more frequent intervals from tributaries and from 

all municipal and industrial wastetreatment plants. Collection of BOD samples began 2-7 days before each study, depending on traveltime through the reach. 

3. During the study period, several recording 

monitors were operated continuously in 

each reach to determine diel variations in 

temperature, DO, specific conductance, and 

pH. Algal photosynthesis and respiration 

were discernible from the data at several 

sites. 

4. All river- and waste-BOD samples were incubated for 20 days, and DO measurements 

were made at frequent intervals to permit 

C19 
determination of BOD rate curves and ultimate BOD (BODult). 

5. The possibility of nitrification was evaluated 

by (a) running inhibited (Tuffey, 1973) and 

noninhibited BOD's and, during several 

studies, by (b) analyzing river and wastewater samples for ammonia-nitrogen, 

nitrite-nitrogen, and nitrate-nitrogen. 

6. The significance of benthal oxygen demand 

was evaluated by sampling bed materials in 

areas that had historically contained sludge 

deposits and by examining results of vertical 

DO traverses at numerous cross sections. 

7. Refined calculations of time-of-travel and reaeration rates were made for short subreaches of the river using detailed crosssectional geometry (200-1,000 ft (60-300 m) 

intervals) data obtained from the U.S. Army 

Corps of Engineers. New cross-sectional 

data were obtained by echo sounding in 

reaches where there was reason to suspect 

recent changes in channel geometry. 

8. Black-and-white and color-infrared photography of the main stem of the Willamette 

was obtained from the Corps of Engineers 

and from the Earth Resources Assessment 

Project of the National Aeronautics and 

Space administration (NASA). The photography was used, in conjunction with field observations, to examine river morphology 

and other physical factors. 

RATIONALE FOR THE DATA PROGRAM 

The program was designed to provide reliable 

data on the major cause-effect relationships that 

affect DO depletion. Emphasis was placed on obtaining data for direct calculation of required 

loading parameters and model coefficients. This 

emphasis was made to avoid reliance on literature values, arbitrary guidelines, and the estimation of model coefficients by computerized curve 

fitting. 

All loading data were determined by analysis of 

waste-water and tributary stream samples collected specifically for the study. No use was made 

of existing data, nor were any loadings estimated 

from production or population records. As the 

municipal and industrial waste waters received 

secondary treatment, BODutt loadings could not 

be determined by applying a rule-of-thumb constant to 5-day BOD (BOD5). Thus, all carbonaceous loadings were obtained by running 20-day 

BOD's (BOD20) and using the resultant rate 

curves for calculation of· ultimate demands. The 

nitrification inhibitor (Tuffey, 1973) was used 

because most effluents and several tributaries 

contained appreciable concentrations of 

ammonia-nitrogen. The actual ammonia loadings 

were determined by direct analysis of aliquot 

samples. 

Data were collected to permit calculation of the 

coefficients for deoxygenation, reaeration, and 

nitrification. At least 15 BOD20 rate curves were 

determined at each sampling station for calculation of river-deoxygenation coefficients. The detailed channel-geometry data were assembled so 

that reliable reaeration rates could be calculated 

for each subreach of the river. Similarly, the 

synoptic, in-river data on ammonia decay and 

nitrate generation were collected to permit calculation of nitrification rates on a reach-by-reach 

basis. 

The horizontal and vertical traverses for DO, 

temperature, and BOD were made to determine if 

samples from the centroid of flow were representative of the station cross sections. Only cross 

sections that reconnaissance data indicated were 

well mixed were sampled. As a result, BOD20 

levels seldom varied significantly either horizontally or vertically within the cross section. However, vertical variations in DO contents were 

usually observed owing to photosynthetic activity. The continuous-monitor records of DO and 

temperature were collected to estimate the impact of algal activity on river DO. The continuous 

DO curves were used to calculate net productivity 

according to the method developed by Odum 

(1956), as modified by Slack, Averett, Greeson, 

and Lipscomb (1973). 

Calibration and verification have been completed (1976), and the model has been used to 

predict the impacts on DO of various alternative 

plans for river-quality management (Rickert, 

Hines, and McKenzie, 1976). 

IMPACT OF LAND-USE ACTIVITY 

ON EROSION AND RIVER QUALITY 

THE METHOD-INTERPRETIVE MAPPING 

BASIS 

A new procedure was applied in the Willamette 

River basin to define the relationships between 

terrain properties, land-use activities, and erosional problems. The procedure was based on inC20 
terpretive mapping and derived from approaches 

used to delineate erosional problems in the San 

Francisco Bay region (Brown and Jackson, 1973, 

1974). 

The premises of the procedure were as follows: 

(1) Terrain properties determine the potential 

erodibility of land in its natural state, (2) landuse activities represent cultural disruptions of 

terrain surfaces, and (3) different combinations of 

terrain properties and land-use activities result 

BASIN 

PHOTOMOSAIC 

COLOR-IR 

PHOTOGRAPHS 

-

CLIMATE J 

'-

-

SLOPE I 

GEOLOGY I 

.._ 

SOILS I 

RUNOFF 

DESCRIPTION OF 

LAND USERIVER QUALITY 

RELATIONSHIPS 

CD 

in different types and severities of erosional problems. The procedure was used to produce an 

erosional-province map through the integration 

of information on land-use activities, critical terrain factors, and existing erosional-depositional 

features. Development of the map is illustrated 

by steps 1 and 2 of figure 7. The two illustrated 

steps actually involved a sequence of three discrete steps: 

1. Identification of land-use activities. This in-

(I) 

a: 

0 

t; 

<{ 

LL 

w 

(I) 

::::> 

6 

z 

<{ 

...J 

Q) 

-

~ 

EROSIONAL 

PROVINCE 

MAP 

EROSIONAL 

IMPACT 

MATRIX 

I--

I--

FIGURE 7.-Process of assessing the impacts ofland-use activity on erosion and river quality. 

C21 
volved preparation of a photomosaic base 

from aerial photographs at a scale suitable 

for recognition of natural and altered 

surface-cover conditions. The observed cover 

conditions were then correlated with actual 

land-use activities as identified from fieldchecked interpretation of stereomagnified, 

false-color-infrared (IR) aerial photographs. 

In the Willamette River basin, surface cover 

provided by natural vegetation is normally 

dense enough to prevent serious erosional 

problems (Willamette Basin Task Force, 

Appendix G, 1969). Thus, severe erosional 

problems are caused primarily by those activities of man that disrupt the natural surface cover. 

2. Collation of the critical physical factors that 

control terrain-surface stability. For the Willamette River basin, the critical regional 

scale factors are slope and geology. The collation involved development of criteria to 

evaluate the relative role of each factor, followed by preparation and visual integration 

of overlay maps to delineate (on the photomosaic) distinctive ''erosional provinces." 

All areas mapped as a given province have 

similar terrain characteristics and, where 

unaffected by man, have similar potentials 

to erode or to receive sediment. 

3. Mapping of erosional-depositional features. 

High-altitude, false-color-IR photographs of 

the basin were scanned under stereomagnification to locate distinctive erosionaldepositional features. Next, the nature of 

each feature (for example, gully, landslide, 

slump, streambank erosion) was determined 

through field -checked photointerpretation, 

and then mapped by symbol on the photomosaic base. 

The completed erosional-province map provides 

a means for comparing the erosional-depositional 

features that exist in the basin as a result of the 

interaction between terrain properties and landuse activities. 

PRESENTING THE RESULTS 

The erosional province map contains information that is important to resource planning, but in 

a form that is difficult to apply. To overcome this 

difficulty, an erosional-impact matrix was devised to synthesize the information into an easyto-use format (figure 7, step 3). 

The matrix was produced by listing erosional 

weighting factors for land-use activities as rows 

and additional sets of factors for slope and geology 

as columns. The body of the matrix is composed of 

numerical, erosional-impact ratings (ranging 

from <103 to >103) resulting from the product of 

the weighting factors for land-use activity, slope, 

and geology. 

The magnitude of the numerical ratings indicates the relative seriousness of erosional problems likely to develop under the various combinations of erosional provinces (as defined by slope 

and geology) and land-use activities. Although 

the products are numerical, the ranking 

methodology limits their use to providing rough 

estimates of erosional impacts. To account for this 

limitation, the full range of numerical rankings is 

divided into relative-seriousness categories of 

slight, moderate, and great. 

The effect on river quality of erosion and deposition depends on the kind, number, and extent 

of erosional-depositional disturbances and their 

proximity to the river. Ideally, a second type of 

matrix could be used to depict the relative severity of potential river-quality problems that might 

result from the erosion and deposition associated 

with different land-use activities. This concept 

was investigated for the Willamette River basin, 

but existing data were insufficient to define all 

the relationships, and time constraints precluded 

collection of needed new data over so large an 

area. However, the river-quality impact matrix 

may be considered for future studies of smaller 

areal extent. For the present study, qualitative 

discussions are used to trace important relationships between land-use activity, erosion and deposition, and the consequent impacts on river quality (fig. 7, step 4). 

The sequence of maps, matrices, and discussions can provide information in any basin that is 

vital to land-use and river-quality planning. The 

principal attributes are (1) graphic depiction of 

the relationships between terrain properties, 

land-use activities, and erosional impacts; (2) 

provision of information to resource planners in a 

ready-to-use format; and (3) amenability to regular updating to provide information under rapidly 

changing conditions. 

DATA PROGRAM 

Production of the erosional province map required (1) false-color-IR aerial photographs, (2) 

C22 
black-and-white aerial photographs for construction of an up-to-date photomosaic base, and (3) 

data on an array of natural terrain properties. 

FALSE-COLOR-IR PHOTOGRAPHY 

The false-color-IR photographs required for the 

study were taken at high altitude (65,000 ft) by 

NASA and range in scale from 1:32,500 to 

1:130,000. The photographs have high resolution 

and come on continuous overlapping transparencies to facilitate stereoscopic viewing. 

The false-color-IR photographs allow a distinction among many important land-surface features not possible from other photography; for 

example, timber, other heavy vegetation, and 

crops appear in various shades of red; dirt roads, 

denuded areas, and erosional features such as 

landslides appear white; nonvegetated urban 

areas commonly appear blue gray; and water appears bright blue. These color-enchanced distinctions provide a powerful basis for quick synoptic 

examination of land-use activity and for locating 

and describing erosional-depositional features. 

PHOTOMOSAIC BASE 

An up-to-date photomosaic base was needed to 

permit recognition of major surface-cover conditions and as a compilation base. The mosaic posed 

questions concerning scale, method of production, 

and need for enhancement. 

The question of scale was directly related to the 

size of the Willamette River basin, which, as previously noted, is roughly rectangular, with a 

north-south length of about 150 mi (240 km) and 

an average east-west width of about 75 mi (120 

km) (fig. 1). Selection of a suitable scale required 

the balancing of two factors: ( 1) a scale large 

enough to provide sufficient detail to permit recognition of surface-cover conditions and to define 

erosional-depositional features and (2) a scale 

small enough so that the entire basin could be 

mapped on three or four sheets of convenient size. 

The second factor was important because the objective of the mapping was to provide a synoptic 

view of erosion potential throughout the entire 

basin. The scale of the NASA black-and-white 

photography was 1:130,000, and this was selected 

as a reasonable compromise. This is similar to the 

scale of 1:125,000 used for regional mapping of 

the nearly 7 ,OOO-mi2 (18,000 km2) area in the San 

Francisco Bay Region Environment and Resources Planning Study (U.S. Geological Survey, 

1970). 

Considerable thought was given to the pros and 

cons of constructing a fully controlled, rectified 

mosaic versus a semicontrolled mosaic. A completely controlled, rectified mosaic would have 

provided the best possible base for compilation 

and for accuracy of the final product. However, 

estimates of relative times and costs for construction greatly favored the semicontrolled base. 

Moreover, the original NASA photographs were 

taken from such a high altitude (65,000 ft, 19,800 

m) that distortion in a semicontrolled base would 

be small. Also, the base would be intended only 

for interpretive reconnaissance, not as a basis for 

engineering scaling. The decision was thus made 

to construct a semicontrolled mosaic using photoreduced Geological Survey 15-minute quadrangle 

maps as a basis for control. 

The third question concerned enhancement. 

Consideration of the desired product indicated a 

need for enhancement of both cultural and hydrologic features. Cultural features were enhanced through linework and titles, whereas 

hydrologic features were enhanced through 

linework, titles, and the use of color. The enhancements were made on overlays which were 

photographically composited with the photomosaic base. 

TERRAIN PROPERTY DATA 

As previously noted, erosional provinces in the 

Willamette River basin were delineated through 

the integration of data on geology and slope. 

However, information on climate, soils, and 

runoff was also collated to test delineation 

hypotheses and to provide a basis for discussing 

the resultant map. The following provides a brief 

synopsis of the major sources of data and the 

manner in which existing information was culled 

and collated. 

CLIMATE 

Knowledge of climate and, in particular, the 

precipitation pattern in regard to type, frequency, 

duration, and intensity is critical in determining 

the potential runoff and erosion that can occur on 

a terrain surface. Detailed climatic data were 

available for only a few scattered locations in the 

Willamette River basin. However, an existing 

isohyetal map (Willamette Basin Task Force, Appendix B, 1969) provided useful information on 

C23 
generalized, basin-wide patterns of average annual precipitation. For the regional scale of this 

study (1:130,000), the generalized data were considered sufficient for developing precipitation criteria as a basis for evaluating the importance of 

this factor on erosion potential. 

SLOPE 

Slope is the most important single factor affecting land-surface stability because it determines 

( 1) the susceptibility of rock and soil to downslope 

mass movement and (2) the potential rate of 

runoff and thus the potential for fluvial erosion 

(Leopold, 1968). Generalized slope information 

was available for most of the Willamette River 

basin from the Oregon State Water Resources 

Board (1969). The slopes were grouped in general 

categories, and for most areas this was sufficient. 

An alternative source, used only to a limited extent, was the slope information that could be derived from standard topographic maps of the U.S. 

Geological Survey. In addition, the stereoscopic 

viewing of the false-color-IR photographs allowed 

qualitative slope analysis at any specific location. 

GEOLOGY 

A complete large-scale geologic map of the 

basin was needed to accurately delineate exposures and to classify the various rock units according to erosional characteristics and slope stability. Most of the existing information was 

available from U.S. Geological Survey publications, supplemented by data from the State Department of Geology and Mineral Industries. The 

scales of existing maps ranged from 1:24,000 to 

1:500,000, a 20-fold difference. In addition, different maps used different letter symbols to denote 

the same geologic formations. The cullingcollation procedure consisted basically of three 

steps: ( 1) development of a consistent geologic 

mapping system specifically keyed to isolating 

erosion potential; (2) discussion and crosschecking to determine which maps were the most 

accurate; and (3) where two or more accurate 

geologic maps covered the same area, selection of 

that map closest to the scale of 1:130,000 which 

covered the largest area. . 

SOILS 

Soils maps are needed to delineate characteristics important to erosional potential such as landform position, soil texture, and infiltration capacity. Soils maps for various parts of the basin at 

various scales were available from the Soil Conservation Service, the U.S. Forest Service, the 

Agricultural Experiment Station at Oregon State 

University, and the Oregon State Water Resources Board. The culling-collating process was 

similar to that for geology. An additional difficulty existed because the maps were prepared for 

different purposes and grouped soils according to 

different characteristics. In some cases, the units 

had to be broken into subunits and recombined. 

RuNOFF 

Data on surface runoff and streamflow were 

available from the U.S. Geological Survey in the 

form of basic-data reports and from a hydrologic 

atlas at a scale of 1:500,000 (Oster, 1968). These 

data, in conjunction with basic information on 

geology and soils and the photointerpretation of 

landforms, were used to estimate the perviousness and slope stability of exposed geologic units. 

COMPARATIVE ROLES OF EXISTING AND NEW DATA 

The erosional study consisted of (1) culling and 

collating existing data on terrain properties and 

(2) interpreting new reconnaissance-type data 

made available in high-altitude photographs. 

Large scale photographs could have been obtained from NASA for more detailed interpretations of land-use activities and erosionaldepositional features. However, this potential 

was not pursued because data on the various 

natural features of the terrain did not exist in 

comparable detail nor could such data be collected 

during the time span (2% years) of the study. 

Thus, the scale and scope of existing terrain data 

are the limiting factor in the detail of the regional 

erosional-province rna p. 

POTENTIAL FOR ALGAL PROBLEMS 

INFEASIBILITY OF l\·IATHEMATICAL MODELING 

Concern about the potential for algal problems 

led to a search for a suitable assessment method. 

An applied eutrophication model would have 

been ideal. However, at present, the complex eutrophication process is so poorly understood 

(Hines, Rickert, McKenzie, and Bennett, 197 5) 

that it is virtually impossible to develop applied 

models capable of valid quantitative predictions 

(McGauhey, 1974). Certainly, many years of 

C24 
fieldwork would be required to obtain data 

adequate to model the sources, sinks, and transport mechanisms of algal nutrients. Even more 

data would be needed to quantify the relationship 

of algal growth to nutrient availability and to 

other environmental factors. These considerations indicated it would be impossible to obtain 

adequate data to formulate, calibrate, and verify 

a practical eutrophication model within the 2%-

year time span of the study. 

Instead of a predictive model, a qualitative descriptive study was designed to provide insight 

into the potential for excessive algal growth. 

THE METHOD-DESCRIPTI\TE ASSESSMENT 

Many river-quality problems exist that presently cannot be assessed through modeling, 

mapping or the use of other specific methods. 

However, resource-planning information can be 

obtained for most of these problems through descriptive assessment. Descriptive assessment is 

basic to all other methods because it is the fundamental basis of scientific endeavor. 

Although basic to modeling and mapping, descriptive assessment differs in the mode of approach. The other methods proceed primarily by 

snythesis, whereas descriptive assessment depends primarily on analysis. For example, in 

modeling, we attempt to obtain the desired information by adding together various building 

blocks and combining them into a more highly 

organized structure; this is synthesis. In contrast, 

the approach to descriptive assessment is to separate a large system into its component parts to 

provide clues to the problem; this is analysis. 

As used in the Willamette study, descriptive 

assessment embodied problem definition, devising of hypotheses, collection and analysis of data, 

and exclusion of disproved hypotheses. For some 

problems, the cycle was repeated several times to 

refine the remaining possibilities. The final results are qualitative, because they provide no 

numerical predictions, but rather a general 

knowledge of the ways in which environmental 

and cultural factors combine to control riverquality phenomena. 

The basic working hypotheses for the Willamette algal study were: 

1. Nuisance algal growths will develop provided 

the loading of major nutrients to the Willamette remains constant or increases, and 

loading ratios remain in proportion. This, in 

turn, is based on the hypothesis that certain 

undesirable algae (mostly blue-greens and 

certain greens) compete better than desirable species (most diatoms and green algae) 

under a condition of low carbon concentrations and high nitrogen and phosphorus concentrations. 

2. Algal growth is limited by a scarcity of certain 

trace elements. 

3. Nuisance algal growths are prevented by low 

water temperatures. 

4. Nuisance algal growths are prevented by short 

detention times of water in the Willamette. 

5. Nuisance algal growths are prevented by high 

summertime turbidities. 

DATA PROGRA~I 

ROLE OF EXISTING DATA 

Available data on physical characteristics (fig. 

4 and table 3) were analyzed to determine which 

reaches of the river are most susceptible to possible algal problems. Conditions of high temperature and slow-moving, slowly mixing water would 

seem to be most favorable to the nuisance forms of 

green and blue-green algae. Thus, should nuisance algal growths develop in the river, they 

would probably occur in the Tidal Reach and the 

"Newberg Pool." 

Existing water-quality data were examined 

with regard to ( 1) nutrient loading, (2) nutrient 

concentrations in river water, (3) the types and 

numbers of algae, and (4) physical factors such as 

temperature and light availability. The data provided a good idea of what to expect for the loading 

and, as previously noted (see "Algal Problem Potential"), for the river concentrations of carbon, 

nitrogen, and phosphorus. No information was 

available on the loading and availability of minor 

algal nutrients. 

Excellent temperature data were available, but 

the sparse data that did exist on algal species, 

algal quantities, and light penetration were from 

the mid-1960's when the river still received some 

untreated and primary treated waste waters. The 

relevance of the data to 1973 conditions was questionable, so a reconnaissance algal-monitoring 

study was immediately devised. However, the 

existing algal data were later analyzed in conjunction with the new information on the Willamette and with historical data from other rivers. These analyses were made to relate algal 

C25 
conditions in the Willamette to past conditions 

and to anticipate problems observed in similar 

rivers elsewhere. 

RECONNAISSANCE 

The reconnaissance-level work consisted of two 

items: 

1. A plankton-monitoring network of five stations with three in the Tidal Reach (RM's 7, 

12.8, and 21.2) and two in the ''Newberg 

Pool'' <RM's 35 and 50). The stations were 

sampled biweekly from June through September 1973 and 1974 and occasionally during other months of each year. At each station, samples were depth integrated 

throughout the euphotic zone at several 

points in the cross section. Laboratory 

analyses were then made of the species and 

numbers of algae and algal-nutrient concentrations. In situ measurements were 

made of DO, pH, temperature, and light 

penetration. 

2. Periodic analyses of waste-water effluents and 

tributary inflows to determine the river 

loading of major algal nutrients. 

Information obtained from this reconnaissance 

was used to design a series of intensive studies. 

INTENSIVE STLTDIES 

The intensive studies were designed to document the chemical and physical conditions associated with the onset of peak algal growth and 

the impact of this growth on river quality. The 

work included the following items which were 

done simu~taneously. 

1. Intensive sampling at the five stations included in the reconnaissance network. Samples for analysis of algae and nutrients were 

collected at least once per day. Incident light 

and light penetration were measured several times each day, whereas temperature, 

DO, and pH were monitored continuously. 

2. Algal production-respiration determinations 

using the light- and dark-bottle DO and 

C-14 techniques (Slack, Averett, Greeson, 

and Lipscomb, 1973). These were made at 

several depths at the Tidal Reach stations 

on six different occasions. 

3. Enrichment bioassays run at the same stations and depths, and by the same techniques, as the basic production-respiration 

tests. Treatments included enrichment with 

nitrogen and phosphorus (separately and in 

combination), mixtures of micronutrients, 

domestic sewage effluents, and pulp- and 

paper-mill effluents. The tests were run on 

three occasions. 

RATIONALE FOR THE DATA PROGRAl\I 

The overall data program was designed to gain 

insight into the factors that control the growth of 

algae under present river conditions. The reconnaissance studies provided information on the 

general availability of algal nutrients, the 

growing-season variations of key physical factors, 

and the response in terms of algal species and 

numbers. The intensive studies provided similar 

information during periods of peak algal growth. 

In addition, the light- and dark-bottle tests and 

the diel records of DO and pH measured the impact of peak growth on the river. The enrichment 

bioassays determined the extent to which the 

growth of algae was nutrient limited and the potential impact of adding higher concentrations of 

nutrients to the river. 

The data program provided information for 

evaluating the working hypotheses and supplied 

a baseline from which trends can be established 

and predictions made as subsequent data become 

available. Sufficient insight was attained to determine which factors must be managed in the 

Willamette to avoid future algal problems (Rickert, Petersen, McKenzie, Hines, and Wille, 1976). 

TRACE-METAL OCCURRENCE 

THE :METHOD-DESCRIPTIVE ASSESSMENT 

Prior to this study, virtually no data existed for 

the Willamette River system on the content of 

potentially toxic trace metals in the water, sediment, and food chains. Data were so sparse as to 

preclude even a preliminary assessment of 

whether metal concentrations were low, moderate, or critically high. To partly fill this void, a 

descriptive assessment was designed to provide 

basinwide information on the concentration and 

distribution of trace metals in river-bottom sediments. 

The objectives of the assessment were to provide (1) baseline information for future comparison and (2) a basis for determining whether the 

analyzed metals were present in high enough 

concentrations to represent an ecological threat. 

The first goal was fully attainable, the second 

C26 
only partly, because scientists presently lack the 

ability to relate with confidence the determined 

concentrations of trace metals in rivers to specific 

potentials for aquatic organism toxicity. Instead 

of defining toxicity relationships, the present 

study developed a procedure for identifying trace 

metals that were present in concentrations indicative of pollution. Through this process of red 

flagging, specified metals were classified as 

worthy of more intensive study. 

Formulation of the assessment involved (1) 

selection of a sampling medium suitable for surveying the basinwide occurrence of trace metals 

and (2) development of a process for distinguishing between natural and polluted trace-metal 

concentrations. 

SAMPLING MEDIUM 

Bottom sediments have two major characteristics that make them a desirable sampling 

medium for a reconnaissance-type study. First, 

fine sediments can usually be found and sampled 

from most reaches of most large rivers. Second, 

because trace metals associate strongly with particulate materials, bottom sediments act as metal 

integrators during periods of low-flow velocities 

when the riverbed is not being scoured. During 

such periods, the riverbed is a depository for incoming sediments, and these, as well as the sediment already in place, can serve as scavengers of 

dissolved metals from the passing water. Bottom 

sediments collected during a period of low-stable 

flow thus provide information on the presence of 

metals during the period and can be used to delineate areas of anomalously high concentrations 

and possible sources. 

In contrast to bottom sediment, water, suspended sediment, and aquatic organisms are less 

desirable as a medium for conducting a synoptic, 

trace-metal reconnaissance. Water is, in some 

ways, the least desirable because a water sample 

collected from a flowing river represents the conditions that exist at a single instant in time. If the 

discharge of metal wastes is intermittent (as is 

often the case), downstream water samples may 

miss the pollution. Moreover, even with constant 

discharge of metals, water samples collected at 

distant sites may show little or no pollution because the metals could well be removed from solution by sorption onto sediment particles during 

downstream passage. 

With intensive sampling, suspended sediment 

is an excellent medium for determining tracemetal occurrence during specific runoff events. 

However, suspended sediment is too transitory to 

provide a sound sampling basis for synoptic, 

basinwide surveys. Aquatic organisms are the 

focus of toxicity studies, but they too represent a 

poor medium for determining the basinwide occurrence of trace metals. The major drawback to 

their use is the improbability of finding enough of 

specific life stages of selected organisms at all 

predetermined sampling sites. 

DISTINCTION BETWEEN NATURAL BACKGROUND 

AND POLLUTION 

A process was needed to distinguish tracemetal concentrations representing natural 

background conditions from those caused by pollution. A two step process was developed for this 

purpose: 

1. Plot metal concentrations in fractionated 

fine materials (see HData Program") on normal 

probability paper according to the method described by Velz (1970, p. 522-542). Concentrations which follow a normal distribution are 

suggestive of natural background and all other 

concentrations are indicative of pollution (see 

Rickert, Kennedy, McKenzie, and Hines, 1976). 

2. Compare the trace-metals concentrations 

suggested as representing natural background 

conditions from step 1 to published data for soils 

of the Willamette River basin and to worldwide 

averages for clays and shales. Data for fine fractions of "natural-condition soils" are available in 

Shacklette, Hamilton, Boerngen, and Bowles 

(1971) and in printouts from computerized data 

storage banks of the Geological Survey. 

Worldwide averages of metal concentrations in 

clays and shales are reported by Parker (1967) in 

a paper on the geochemistry of the Earth's crust. 

DATA PROGRAM 

Sampling sites were selected to provide ( 1) general coverage of the entire main stem of the Willamette and (2) detailed coverage of locations 

below possible sources of trace metals. Rivervelocity data and low altitude aerial photographs 

(U.S. Army Corps of Engineers, 1973) were used 

to determine areas where fine materials were 

likely to be found under low-flow conditions. 

The objective of field sampling was to obtain 

enough fine-grained material from each site to 

provide a basis for laboratory analyses. In genC27 
eral, no attempt was made to sample cross 

sections in a detailed manner, because such 

sampling was not needed to meet the 

reconnaissance-type objectives. Samples were collected in late September 1973 after a period of 

more than 4 months of steady low flow. Thus, the 

results represent a synoptic picture of trace-metal 

occurrence over a period of considerable length. 

The sampling network was designed to place 

special emphasis on the lower end of the Tidal 

Reach, because this is the primary depositional 

zone of the river. (See ~(Tidal Reach.") Satisfactory 

samples were obtained in the Tidal Reach with a 

Petersen dredge (Slack, Averett, Greeson, and 

Lipscomb, 1973) by taking and compositing two 

or three bites at the visual center of flow. The 

visual center of flow was used in preference to the 

center of the cross section because, in many subreaches, the channel and nearly all flow is near 

one bank. The sampling site for each cross section 

was determined by combining field observations 

with information contained in aerial photographs 

(U.S. Army Corps of Engineers, 1973). 

In many upstream subreaches the riverbed is 

almost completely covered with gravel-sized 

materials. In these locations, the sampling approach consisted of searching with an Ekman 

dredge for small areas of fine-grained sediments. 

The samples, and hence the determined tracemetal concentrations, are thus unrepresentative 

of the channel-bed materials. However, the 

measured concentrations do provide an indication 

of the relative occurrence of trace metals in the 

fine sediments of each subreach. The sampling 

approach simply uses the fine materials in bed 

sediments as a natural trace-metal concentrator. 

Forty-four samples were collected and aliquots 

of each were size fractionated so that metal concentrations could be compared to the percentages 

of clay, silt, and sa.nd on a sample-by-sample 

basis. 

The metal analyses were performed on subsamples sieved through 2-mm screens and on 

aliquots of<20-,um materials obtained by further 

fractionation of the <2-mm materials. The 

<20-Mm materials contained the clay and fine silt 

fractions from each whole sample and were 

roughly comparable in grain size to clays and 

shales. The fractionation at 20-,um thus provided 

a basis for comparing the trace-metal results to 

published geochemical data for these rock types. 

More importantly, the use of 20-,um fractions suecessfully standardized the variations in metal 

concentrations that otherwise would have resulted from sample-to-sample differences in the 

proportion of fine-grained materials. The <20-,um 

data were proven to provide a sound comparative 

basis for detecting trace-metal pollution. 

Metals analyses were made by two methods. 

Semiquantitative six-step spectrographic analysis (Myers, Havens, and Dunton, 1961) was used 

to scan the presence and approximate concentrations of 50 elements. This method was primarily 

used to determine if any of the wide array of investigated metals was present in anomalously 

high concentrations. 

Atomic-absorption spectrophotometry was used 

to determine more quantitatively the concentrations of arsenic, cadmium, chromium, copper, 

lead, mercury, silver, and zinc (Ward and others, 

1963; 1969). These eight metals were specifically 

selected for more quantitative analysis because 

they are widespread by-products of man's activities and are potentially toxic to aquatic organisms. 

RATIONALE FOR THE DATA PROGRAM 

The data program was designed to provide 

baseline reconnaissance-type information. The 

purpose was to collect enough samples of a suitable medium so a synoptic basinwide picture could 

be developed of trace-metal occurrence. In contrast to the programs for the other three project 

elements, no attempt was made to collect the 

kinds and intensities of data required to define 

cause-effect relationships. By applying the two 

step screening process to the collected data, it was 

possible to detect several cases of trace-metal pollution and to identify the sources (Rickert, Kennedy, McKenzie, and Hines, 1976). 

SUMMARY AND CONCLUSIONS 

The beginning of a comprehensive environmental assessment project is a time of many questions 

and few answers. The questions include all sorts 

of matters, such as what are the goals and objectives? With whom should we coordinate? What 

are the critical problems? What scientific 

methods should we use? How should we design 

the data programs? To whom should we aim the 

results and reports? 

The initial uncertainty is normal and underC28 
standable. The first task in project design is to 

reduce the uncertainty by carefully defining the 

goals and objectives. The remaining design task 

is to answer all other questions within a goalobjective framework that is flexible enough to 

permit useful change and expansion as the project 

evolves. 

The first several months of the Willamette 

study were used to ( 1) set carefully defined objectives; (2) determine the maximum possible workload in regard to the constraints of time, funding, 

and manpower; and (3) to identify and meet with 

local, State, and Federal agencies who were interested in the conduct and potential results of an 

intensive assessment of Willamette River quality. By the end of the second month, the discussions clearly indicated that the goal of producing 

sound, adequate information on important problems would require that the study duration be 

expanded from 2 to 2¥2 years. Because this was a 

prototype project, the framework provided ample 

flexibility to lengthen the period of study. However, a careful examination of whether program 

goals and objectives can be met under initial constraints is recommended as an early step in any 

large-scale environmental-assessment program. 

This need exists because such programs are so 

complex and require so much information that it 

is virtually impossible before the study begins to 

define how much time and money will be needed 

to produce useful results. Experienced personnel 

can develop good initial estimates, but attainment of goals and objectives cannot be guaranteed unless initial constraints can be modified. 

Following the change in schedule, discussions 

on the Willamette study continued until eight 

existing or potential river-quality problems were 

identified, briefly evaluated, and ranked on a 

priority basis. The information used to develop 

the priorities came from the discussions, the data 

records of the interviewed agencies, and hydrologic and river-quality records of the Geological Survey. Once the priorities were set, the 

specific elements to be included in the project 

were selected by combining the priority ratings 

with the redefined constraints of time and funding. 

The next step in developing the project was to 

define the hydrology of the Willamette River and 

to determine which aspects of basin hydrology 

needed to be modeled as a basis for assessing the 

selected problems. Existing data on flow, temperature, and channel morphology were sufficient to 

provide a detailed hydrologic description of the 

Willamette River. The collected information was 

used to determine where and when to collect data 

for assessment of each river-quality problem. The 

hydrologic-modeling needs were determined to be 

a mathematical model for simulating reservoir 

releases and a hydraulic model of the Tidal 

Reach. 

The focus of project development then switched 

to selection of suitable assessment methods and 

the design of data programs to analyze the four 

river-quality problems. The methods were 

selected on the basis of the context and complexity of each problem, availability of data and the 

ability to collect new data, and the degree of detail needed to provide useful results. The data 

programs were carefully tailored to each problem 

and the selected assessment method through the 

approach of (1) identifying data needs, (2) collating existing data, (3) collecting reconnaissancelevel data, and (4) collecting intensive data at 

critical times and places. Except for the tracemetal reconnaissance, the goal of each data program was to define the important cause-effect relationships that controlled the specified problem. 

This goal was necessary because only when 

cause-effect relationships were defined could assessment information be used to predict the impact of planning and management alternatives. 

The design of the Willamette River Basin 

Study is presented in this circular as an aid and 

stimulus to others who are interested in riverquality assessment. The report is purposely detailed because the authors believe there is great 

need in the literature for open discussion of approaches, methods, and data programs for practical assessment of river-quality problems. The authors encourage other environmental scientists to 

conceptualize and record their approaches to resource assessment so others can build upon their 

knowledge and experience. 

ACKNOWLEDGMENTS 

We wish 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 Willamette Study, the Group 

included Howard B. Brown, Robert A. Canhan, 

C29 
Edward J. Cleary, Laurence R. Jahn, John E. 

Kinney, Walter A. Lyon, John A. Roller, and 

Clarence J. Velz. The authors also acknowledge 

the helpful review suggestions of Robert M. Beall 

and James C. Warm an. 

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C31