Methodology for River-Quality 

Assessment with Application to the 

Willamette River Basin, Oregon 

By David A. Rickert, Walter G. Hines, and Stuart W. Mc:Kenzie 

RIVER-QUALITY ASSESSMENT OF THE WILLAMETTE BASIN, OREGON 

G E 0 L 0 G I C A L 5 U R V E Y C I R C U L A R 715-M 

1976 
United States Department of the Interior 

THOMAS S. KLEPPE, Secretary 

Geological Survey 

V. E. McKelvey, Director 

Library of Congress Cataloging in Publication Data 

Rickert, David A. 1940-

Methodology for river-quality assessment with application to the Willamette River Basin, Oregon. 

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

(Geological Survey Circular 715-M) 

Bibliography. 

Supt. of Docs. no.: I 19.4/2:715-M 

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

McKenzie,StuartW.,jointauthor. Ill. Title. IV. Series. V. Series: UnitedStatesGeological Survey Circular 715-M. 

QE75.C5 no. 715-M[TD224.07] 557.3'08s[551.4'83] 76-608291 

Free on application to Branch of Distribution, u.s. Geological Survey, 1200 South Eads Street, Arlington, VA 22202 
FOREWORD 

The American public has identified the enhancement and protection of river 

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

made in the past few years to improve the quality of 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 uRiver-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 

Forevvord ____________________________________________ III 

Summary of conclusions and implications ______________ M1 

Conclusions for the Willamette River basin________ 2 

Dissolved-oxygen (DO) depletion______________ 2 

Potential for algal problems __________________ 2 

Trace-metal occurrence ______________________ 2 

Land use and erosion ________________________ 3 

Implications for the scientific and engineering 

community-------------------------------- 3 

The need for synoptic data-collection programs ------------------------------------ 3 

Utility and limitations of mathematical 

models ____ _ _ ____ __ ________ ____ __ ________ __ 4 

The nature of dissolved-oxygen depletion in a 

river having complete secondary treatment__ 4 

Implications for river-quality planning and management__________________________________________ 4 

The need for localized studies ________________ 4 

The need for alternative strategies to advanced 

vvaste treatment -------------------------- 5 

The cost of conducting river quality assessments_ 5 

Acknovvledgments ____ ____ ________ ______ ______ _______ 5 

Introduction ____ __ ____ __ ______ ______ __ _____ _ ____ __ __ 6 

River-quality assessment and its relation to riverbasin planning -------------------------------- 7 

Physical setting__________________________________ 8 

Geologic overvievv ---------------------------- 10 

Willamette River morphology ________________ 10 

Reservoirs and historical streamflovv patterns__ 12 

Project framevvork ------------------------------ 12 

Duration------------------------------------ 12 

Manpovver ---------------------------------- 14 

Project elements ---------------------------- 14 

Dissolved-oxygen depletion __________________________ 14 

Background ------------------------------------ 14 

Study method-mathematical modeling __________ 15 

Data program ---------------------------------- 15 

Dissolved-oxygen regimen ________________________ 16 

Dissolved-oxygen profiles ____________________ 16 

Nitrification -------------------------------- 17 

Carbonaceous deoxygenation __________________ 18 

BOD loading ---------------------------- 19 

Concentrations and rates ________________ 19 

Dissolved-oxygen modeling ______________________ 19 

Planning implications____________________________ 19 

BOD loading -------------------------------- 19 

Ammonia loading---------------------------- 20 

Lovv-flovv augmentation ______________________ 20 

Undetermined oxygen demand ________________ 23 

Summary and conclusions________________________ 24 

v 

Page 

Potential for algal problems ------------------------ M25 

Background ------------------------------------ 25 

Algal nutrients---------------------------------- 26 

Nitrogen and phosphorus loadings ____________ 26 

Observed concentrations of nitrogen, phosphorus, 

and silica __________________________________ 26 

Algal populations-------------------------------- 28 

Primary productivity ----------------------------. 30 

Examination of the vvorking hypotheses __________ 30 

Lovv-temperature limitation __________________ 30 

Light limitation ---------------------------- 30 

Trace-nutrient limitation ____________________ 31 

Major-nutrient limitation -------------------- 31 

Carbon __________________________________ 31 

Nitrogen and phosphorus ________________ 32 

Detention-time limitation -------------------- 33 

Observed and reported relationships ______ 33 

Role of detention time and light penetration 

in controlling biomass and the nature of 

algae __________________________________ 33 

Summary and conclusions------------------------ 35 

Trace-metal occurrence ------------------------------ 35 

Background ------------------------------------ 35 

Possible sources of trace metals ------------------ 35 

Sampling approaches and rationales ______________ 37 

Laboratory procedures and rationales ____________ 40 

Physical procedures-------------------------- 40 

Analysis of metals -------------------------- 40 

Results __________________________________________ 40 

Distinction betvveen natural background and pollution --------------------------------------- 41 

Zinc ---------------------------------------- 42 Lead ________________________________________ 42 

Copper ______________________________________ 45 

FourthLake -------------------------------- 45 

Summary and conclusions------------------------ 46 

Impact of land-use activity on erosion and deposition __ 46 

Background ------------------------------------ 46 

Assessment approach ---------------------------- 47 

Development of the erosional-depositional province 

map--------------------------------------- 47 

Collation of critical terrain factors ____________ 47 

The province concept -------------------- 47 

Province criteria ------------------------ 47 

Province delineation -------------------- 49 

Mapping of erosional-depositional features ____ 49 

Development of the erosional-impact matrix ______ 50 

Land use erosional factors-------------------- 50 

Slope and geologic erosional factors __________ 50 

Application to planning -------------------------- 50 

Summary and conclusions------------------------ 52 

Further studies-------------------------------------- 53 

References ------------------------------------------ 53 
ILLUSTRATIONS 

Page 

FIGURE 1. Schematic showing the interrelation of river-quality assessment to river-basin planning ________________ M8 

TABLE 

2. Map of the Willamette River basin, Oreg., emphasizing the main stem, principal tributaries, and major 

reservoirs-------------------------------------------------------------------------------------- 9 

3. Diagram representing the Willamette River, Oreg., showing distinctive hydrologic reaches and elevation 

profile ---------------------------------------------------------------------------------------- 11 

4. Hydrographs showing Willamette River discharge at Salem, Oreg., 1944, 1964, and 1973 water years____ 13 

5-12. Graphs showing: 

5. Comparison of 1973 with historical DO profiles in the Willamette River for the summer low-flow 

period__________________________________________________________________________________ 16 

6. Inorganic nitrogen concentrations in the Willamette River during mid-August 1974 ____________ 18 

7. DO profiles for selected percentages of the measured point-source BOD loading during mid-August 

1974 ---------------------------------------------------------------------------------- 20 

8. DO profiles: observed during mid-August 1974 and predicted for a BOD5 municipal effluent standard of 10 mg/1 ______________________ _ _____ __________ ______________ __ _____________ _ ____ __ 21 

9. DO profiles for a hypothetical effluent standard of 10 mg/1 ammonia-nitrogen and for selected percentages of the measured point-source ammonia loading during mid-August 1974 ---------- 22 

10. DO profiles for selected flows with BOD and ammonia loadings held constant at levels measured 

during mid-August 197 4 _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ ___ _ _ _ _ _ _ _ _ _ ____ __ ____ _ _ __ __ _ _ ___ _ _ _ __ _ _ _ ___ _ _ __ 23 

11. DO profiles for selected conditions of flow and ammonia loading ------------------------------ 24 

12. Time and spatial variations of selected major nutrient concentrations in the Willamette River, 

June-~ovember 1974-------------------------------------------------------------------- 27 

13. Diagram showing time variation of algal types in the Willamette River, at mile 8.1, April-September 1963__ 28 

14. Diagram showing time variation of algal types in the Willamette River, at mile 7.0,June-September 1974__ 29 

15. Diagram showing relative abundance of diatoms and blue-green algae in net plankton of the Tualatin River 

at Farmington, Oreg., March-August 1973 ------------------------------------------------------ 29 

16. Graphs showing the vertical distribution of primary gross productivities in the Willamette River, at mile 7.0, 

for selected times during summer 1974 ---------------------------------------------------------- 30 

17. Graph showing effect of nutrient additions on algal productivity ofWillamette River samples, mile 7.0, July 

24, 1973 -------------------------------------------------------------------------------------- 32 

18. Conceptual diagram relating algal biomass and dominant algal types to water detention time and light 

penetration ------------------------------------------------------------------------------------ 34 

19. Map of the Willamette River basin, Oreg., showing sediment sampling sites in the Upstream Reach and 

historical mining areas _____ _ _ _ _ ___ _ _ _____ _ _ _ _ __ _ _ _ ____ _ _ ___ _ _ _ ___ _ _ _ __ _ _ _ _ __ _ _ _ _ __ _ _ ___ _ _ _ __ __ 38 

20. Map showing sediment sampling sites in the Tidal Reach and ~ewberg Pool -------------------------- 39 

21. ~ormal-probability plots of zinc concentrations in less than 20-micrometre materials____________________ 43 

22. ~ormal-probability plots of lead and copper concentrations in less than 20-micrometre materials ________ 44 

23. Map showing erosional-depositional provinces in part of the Molalla River subbasin __________________ 48 

1. 

2. 

3. 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

12. 

TABLES 

Page 

Selected physical characteristics of the main stem Willamette River, Oreg _____________________________ Mll 

Existing or potential river-quality problems: Willamette River basin, Oreg ---------------------------- 14 

Dry-weather 1974 ultimate BOD loading, Willamette River, Oreg ------------------------------------ 19 

Estimated dry-weather 1974 nutrient laodings, Willamette River, Oreg -------------------------------- 26 

Possible sources of trace metals in the Willamette River system -------------------------------------- 36 

Concentrations of trace metals in bottom sediments from the Willamette River and adjacent waters ______ 41 

Geographic distribution of trace-metal concentrations in the <20JLm materials ofbottom sediments from the 

Willamette River and adjacent waters _____ _____ ________ ______ ______ __________________ _____ _____ 42 

Concentrations of trace metals in Fourth Lake ------------------------------------------------------ 46 

Erosional-depositional provinces delineated in the Willamette River basin, Oreg ------------------------ 49 

Erosional-depositional features mapped in the Willamette River basin, Oreg ____________________________ 50 

Matrix for estimating interactive erosional impact of land-use activities with terrain properties of geology 

and slope, Willamette River basin, Oreg -------------------------------------------------------- 51 

Relative erosional factors associated with agricultural and forestry-logging activities, Willamette River 

basin, Oreg ____ _ _ ___ _ _ _ __ ___ _ _ _ _ __ _ _ _ __ __ __ _ _ ___ _ _ _ _ _ __ _ _ _ ___ _ _ __ _ __ _ _ _ ___ _ _ _ __ __ _ _ __ _ _ _ _ __ _ _ __ 52 

VI 
CONVERSION FACTORS 

Factors for converting English units to the International System of Units <SI> 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 

in. (inches) 

ft (feet) 

ft/mi (feet per mile) 

ft/s (feet per second) 

ft3/s (cubic feet per second) 

Mgal!d (million gallons per day) 

acre-ft (acre-feet) 

mi (miles) 

mi/mi2 (miles per square mile) 

mi2 (square miles) 

lb/d (pounds per day) 

ton (short, 2,000 lbs) 

tons/acre/yr (tons per acre per year) 

Multiply by 

2.540x 1()1 

3.048xl0-1 

1.894xt0·1 

3.048x10-1 

2.832x10-2 

4.381xl0-2 

1.233x 10-a 

1.609 

6.212 X 10"1 

2.590 

4.536x10-1 

9.072x 10·1 

2.242 

VII 

mm (millimetres) 

m (metres) 

Metric (81) 

m/km (metres per kilometre) 

m/s (metres per second) 

m3/s (cubic metres per second) 

m3/s (cubic metres per second) 

hm3 (cubic hectometres) 

km (kilometres) 

km/km2 (kilometres per square kilometre) 

km2 (square kilometres) 

kg/d (kilograms per day) 

t (tonne) 

t/hm2/yr (tonnes per square hectometre per year) 

Methodology for River-Quality Assessment with 

Application to the Willamette River Basin, Oregon 

By David A. Rickert, Walter G. Hines, and Stuart W. McKenzie 

SUMMARY OF CONCLUSIONS 

AND IMPLICATIONS 

Comprehensive river-quality assessments are 

critically needed in most areas of the country. Resource managers will soon be faced with major 

decisions concerning advanced waste treatment 

without having the necessary background information. The achievement of desirable river quality at acceptable cost will require that resourcemanagement decisions be based on sound information, not on arbitrary assumptions. 

At present, scientific water-quality assessments are hindered by a scarcity of appropriate 

data and the absence of a unifying national 

framework for study methodology. Several years 

ago, this limitation was recognized by the Department of the Interior Advisory Committee on 

Water Data for Public Use. At that time the 

committee recommended the Geological Survey 

conduct a pilot interdisciplinary river-quality 

study. The objectives set forth for the study were 

to: (1) define a framework for designing and conducting comprehensive assessments of riverquality problems, (2) determine the data required 

to analyze different types of 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 assessing resourcemanagement alternatives in terms of the potential impacts on river quality, and (5) apply the 

framework, data programs, and methods to assess 

the critical river-quality problems of a major 

river basin. 

In January 1973, the Survey responded by initiating a prototype river-quality assessment of 

the Willamette River basin, Oregon. Reasons for 

selecting this basin included the availability of 

formalized basin-management plans and the 

existence of several land-use projections. The 

study therefore allowed for an evaluation of existing planning and management alternatives. 

Furthermore, the Willamette was the largest 

river in the Nation on which all major pointsource, municipal and industrial discharges received secondary waste-water treatment. Also, 

during summer, riverflows were augmented by 

releases from a system of 11 reservoirs. Thus, by 

choosing the Willamette, it was possible to appraise the relative importance of waste-water 

treatment and flow augmentation on the quality 

of a major river. 

In establishing a framework for the prototype 

assessment, the Survey gave particular consideration to optimal study duration, staffing, and the 

specific problems to be evaluated. Regarding the 

duration, a compromise was sought between taking enough time to do a research-oriented study 

and so little time that unexpected problems and 

questionable results could not be evaluated. A 

study duration of2lh years, beginning in January 

and allowing two summer field seasons, was 

finally selected. In this time, problems could be 

identified, studied, evaluated, and rechecked. The 

2lh-year duration also provided a reasonable time 

frame for response to the needs of resource managers. 

Staff needs were based on an interdisciplinary 

team-oriented approach. The selected team was 

Ml 
comprised of scientists and engineers experienced 

in river work and trained in the discipline 

categories of hydrology, sanitary chemistry, 

aquatic biology, mathematical modeling, and 

geology. 

Specific work elements for the program were 

selected in discussions with State, interstate, and 

Federal agencies concerned with river-quality 

management. Eight existing or potential problems were identified. Following evaluation and 

ranking, the following four were selecteddissolved-oxygen (DO) depletion, potential for 

algal problems, trace-metal occurrence, and the 

impact of land-use activity on erosion. 

CONCLUSIONS FOR THE WILLAMETTE RIVER BASIN 

Detailed results of the four project elements are 

described in a series of chapters in U.S. Geological Survey Circular 715. Here, brief conclusions 

drawn from the results illustrate their impact on 

resource planning and management in the Willamette River basin. 

DISSOLVED-OXYGEN (DO) DEPLETION 

Historically, severe DO depletion during summer has been the critical quality problem in the 

Willamette. In recent years, summer DO levels 

have increased dramatically. This increase is the 

result of secondary biological treatment of all 

point-source wastes (municipal and industrial) 

and of streamflow augmentation from storage 

reservoirs. 

Although secondary treatment improved river 

quality, it resulted in continuous discharge of 

pulp- and paper-mill effluents rather than the 

previously used program of summer storage (in 

lagoons) and winter discharge. The advent of 

biological treatment also resulted in the use of 

ammonium hydroxide for neutralizing the raw 

waste waters at certain pulp and paper mills. 

During the summers of 1973 and 1974, the ammonia in the effluent of one mill caused a large 

DO depletion between river miles 86 and 50 

which previously had not occurred. Reduction of 

ammonia loading from this one source offers a 

relatively simple alternative for achieving a large 

(as much as 20 percent) improvement in summer 

DO levels. 

In contrast, at foreseeable levels of development, further reduction in the point-source discharge of organic wastes beyond that achieved by 

efficient secondary treatment would produce only 

limited improvement in DO concentrations. Only 

about half the summertime loading of organic, 

oxygen-demanding wastes presently comes from 

point sources. The other half represents natural 

background demand from essentially pristine 

streams. This demand cannot be removed by 

pollution-control programs. 

Even with basinwide secondary treatment and 

a reasonable limitation on ammonia loading, 

flow augmentation will be needed to maintain the 

Willamette's high DO standards. As basin development continues, reservoir augmentation 

will continue to be necessary even if an advanced 

waste-treatment program is implemented. 

POTENTIAL FOR ALGAL PROBLEMS 

A potential for algal problems may exist in the 

Willamette River because point-source discharges cause the concentrations of nitrogen and 

phosphorus to be high. To date, however, nuisance algal growths have not occurred, and results indicate that the primary reason for 

maintenance of favorable algal populations in the 

Willamette is the short detention time of water in 

the river. 

Perhaps the most important aspect of the short 

detention time is the constant nutrient influx 

that prevents depletion of major nutrients. The 

maintenance of a balance in major nutrient contents favors the growth of desirable rather than 

undesirable types of algae. Thus, in the Willamette the key to keeping algal growth at its 

present balance appears to be control of those factors that maximize summertime flow and 

minimize water-detention time. Such control 

would require maintenance of present levels of 

flow augmentation and avoidance of large increases in summertime diversions. 

The results imply that national or regional 

standards for permissible nitrogen and phosphorus concentrations represent a poor management 

tool. The need for advanced waste treatment to 

remove point-source nitrogen and phosphorus 

should be assessed on a river-by-river basis. 

TRACE-METAL OCCURRENCE 

When present in critical concentrations, many 

materials discharged into rivers are toxic to 

M2 
aquatic organisms. A review of records for the 

Willamette River basin showed there was little 

possibility that toxicity problems could result 

from pesticides and other organic chemicals.· 

However, few data were available on the discharge of trace metals and their possible accumulation in sediments and food chains. 

To partly fill this void, a study was designed to 

determine the concentration and distribution of 

selected metals in river-bottom sediments. The 

objectives were to establish baseline data for future comparisons and to provide an alert to possible accumulations of toxic metals. The study 

approach involved the sampling of bottom sediments under stable low-flow conditions, fractionation of samples to obtain fine-grained materials 

prior to metal analysis, and interpretation of 

trace-metal data through the use of probability 

plots. 

The results suggested that no metals were 

present at levels that might represent an ecological threat. There were moderate enrichments of 

zinc, resulting from industrial discharges, and 

slight enrichments of lead, resulting from urban 

runoff. 

The procedures developed in the study are considered sui table to detect the extent of tracemetal pollution in almost any river. 

LAND USE AND EROSION 

Great increases in population and industry 

over the next 50 years are predicted for the Willamette River basin. At present (1976) the potential impacts of this development on land and 

water quality have not been appraised. 

To permit an initial assessment, a synoptic approach was devised to delineate the relationships 

between physiographic factors, land-use activities, and resultant erosional-depositional 

problems. The approach involved the development of a basin-wide erosional-province map and 

a matrix for rating erosional impacts. Data on 

geology and slope were collated to delineate eight 

units of terrain having different natural potentials to erode or receive sediment. Infrared aerial 

photography was used to identify land-use activities and to map existing erosional and depositional features. The matrix was formulated by 

placing order-of-magnitude erosional factors for 

geology and slope as columns and similar factors 

for land-use activities as rows. 

Together, the map and matrix serve as tools for 

estimating the erosional impact of human activities on different types of terrain. The tools 

have already proven useful for land- and waterresource planning and also for the design of improved data-collection programs. 

IMPLICATIONS FOR THE SCIENTIFIC 

AND ENGINEERING COMMUNITY 

The Willamette Study emphasized the development of approaches, methods, and data programs that would be useful in the assessment of 

other river basins. From this effort, and from the 

study results, certain findings emerged that are 

pertinent to programs of the scientific and engineering community. 

THE NEED FOR SYNOPTIC 

DATA-COLLECTION PROGRAMS 

Except for flow records, the large data base that 

existed for the Willamette River was found to be 

unsuitable for assessment of the three in-river 

problems of DO depletion, algal-problem potential, and trace-metal occurrence. The unsuitability resulted primarily from the fact that existing 

data were collected under routine monitoring-and 

surveillance-type programs. Such programs are 

designed, not to assess specific problems, but to 

provide a general indication of water-quality 

trends and to check for compliance with stream 

standards. Data generated for these purposes are 

generally inadequate for defining the critical 

cause-effect relationships that control most 

river-quality problems. This was true for the Willamette, and indications are that it is true for 

most other rivers in the United States. 

Short-term, intensive synoptic-type studies 

were found to provide the kinds of data required 

for assessing the three in-river problems. In contrast to monitoring- and surveillance-type programs, the synoptic approach can provide a sound 

understanding of cause-effect relationships. This 

permits the critical temporal and spatial changes 

in river quality caused by hydrologic factors and 

waste-water loadings to be more easily recognized 

and quantified. 

From experience gained on the Willamette, we 

believe that intensive synoptic studies will be required in most river basins to develop an 

M3 
adequate information base for managing key 

river-quality problems. 

UTILITY AND LIMITATIONS 

OF MATHEMATICAL MODELS 

Mathematical models can be used effectively in 

the practical assessment of certain river-quality 

problems. However, the models must be based on 

sound data and reliable assumptions, with 

mathematics and the computer used as tools 

rather than as ends in themselves. Because of 

past experiences, the Oregon Department of Environmental Quality was skeptical at the outset 

of the DO study that a mathematical model could 

be formulated for practical use. The project staff 

determined the reasons for skepticism and devised a framework for avoiding the potential pitfalls. As a result, the Department of Environmental Quality has accepted the DO model as a sound 

tool for evaluating pollution-control alternatives. 

The Willamette project team found that there 

were several river-quality problems that currently are too complex to model in a practical and 

useful manner. Such problems include trace-metal 

distribution and the relationship of nutrients and 

algal growth. The project assessed these problems 

through the development of qualitative descriptive approaches. The results clearly demonstrated 

that qualitative approaches can provide adequate 

and reliable information for the management of 

certain river-quality problems. 

THE NATURE OF DISSOLVED-OXYGEN DEPLETION 

IN A RIVER HAVING COMPLETE 

SECONDARY TREATMENT 

The secondary treatment of point-source discharges has drastically changed the selfpurification characteristics of the Willamette 

River. The loadings, in-river concentrations, and 

rates of exertion of biochemical-oxygen demand 

(BOD) were all much lower than in previous 

times. 

The results generally indicate that once efficient secondary treatment has been achieved on 

all waste discharges, other causes of DO depletion 

may become more important than the remaining 

point-source BOD. Also, the rate of carbonaceous 

decay can become so low that, depending on a 

river's hydrologic character, further reduction of 

point-source BOD may have little or no effect on 

DO concentrations. 

Measured BOD concentrations and rates of exertion in the Willamette River are approaching 

those in natural, unpolluted waters. This means 

that the 5-day BOD test can no longer be used to 

estimate the impacts of pollution loadings. It is 

now necessary to conduct 20-day (or other longterm) BOD tests to adequately measure concentrations and to determine rates as a basis for modeling carbonaceous decay. 

As previously noted, nitrification is now a 

prominent DO sink in the Willamette River. The 

process was found to occur only in shallow highvelocity reaches, and within biological slimes attached to rocks (not in the water column). This 

finding supports a recently proposed hypothesis 

and indicates that assessment of nitrification impacts must consider the physical nature of rivers 

in addition to ammonia loadings and water temperature. 

IMPLICATIONS FOR RIVER-QUALITY 

PLANNING AND MANAGEMENT 

Certain of the W illamette Study findings are 

highly significant to national programs for the 

planning and management of river quality. 

THE NEED FOR LOCALIZED STUDIES 

Rivers and their basins are dynamic, and the 

processes within them result from the interaction 

of complex natural factors with man's activities 

and alterations. This interaction creates unique 

local problems which, once adequately assessed, 

often have unique local solutions. Examples in 

the Willamette River are the relative roles of (1) 

BOD and nitrification as causes of DO depletion 

and (2) nutrient concentrations and flow as controllers of algal growth. 

Without the understanding provided by this 

study, Federal and basin planners might logically 

have assumed that further BOD removal was a 

critical priority and that treatment of all point 

sources was necessary to reduce the loading of 

nitrogen and phosphorus. However, the study 

showed first that nitrification, induced largely by 

ammonia loads from one industrial source, was a 

more important cause of DO depletion than 

waste-water BOD loads and second that water detention time, rather than the con~entration of 

nitrogen or phosphorus, was the primary controller of algal growth. 

These examples illustrate the fact that rigid 

M4 
nationwide standards and regulations are likely 

to result in unneeded expenditures in some basins 

and in undesirable quality in others. The proper 

balance can be attained for each river only 

through an intensive, coordinated assessment 

that is keyed to local problems and conditions. 

THE NEED FOR ALTERNATIVE STRATEGIES 

TO ADVANCED WASTE TREATMENT 

While wastewater treatment always will play 

an important role, it is not the sole means of 

river-quality enhancement. Other defensive and 

offensive strategies are also needed. For example, 

in the Willamette River basin, two critical needs 

are reservoir low-flow augmentation to maintain 

desirable summertime conditions of DO and 

land-use planning to alleviate the wide-spread 

problems that arise from erosion and deposition. 

Flow augmentation from storage reservoirs is 

largely responsible for the remarkable improvement in summertime DO concentrations witnessed in the Willamette. Even with the excellent 

pollution control program mounted over the years, 

standards would still be violated in certain subreaches during most summers without low-flow 

augmentation. During dry years, violations would 

occur under natural flow conditions over much of 

the lower half of the river for up to two months. 

These results generally show that low-flow augmentation must be recognized as both a viable 

alternative and as a complement to advancedwaste treatment programs. 

The quality of a river is largely determined by 

the interaction between climate, basin-terrain 

characteristics, and land-use activity. At present, 

the controlling interrelationships are poorly defined because of (1) inadequate recognition of the 

linkages between land-use activity and river 

quality and (2) until recently, lack of a suitable 

basis for synoptic terrain analysis of entire river 

basins. Today, however, there is awakening recognition that an economic linkage exists between 

land development and river-quality management. The situation is now such (in the Willamette and all other river basins) that either 

land-use activity and land runoff are brought into 

the planning picture, or else the ultimate reality 

will be land-imposed constraints on river quality. 

THE COST OF CONDUCTING 

RIVER-QUALITY ASSESSMENTS 

The cost of conducting the Willamette Study 

was about $500,000. Although a considerable investment, this sum is small compared to the 

amount that will be spent for pollution control in 

most large river basins over the next 10 to 20 

years. The information obtained in the Willamette Study provided a sound basis for (1) ascribing planning and managing priorities and (2) 

generating potential savings in pollution-control 

programs by identifying ineffective management 

strategies. As costs for waste-treatment facilities 

continue to rise, the latter consideration is important in keeping public support for environmental 

management and pollution-control programs. 

ACKNOWLEDGMENTS 

Because the Willamette River Quality Assessment was undertaken as a cooperative venture 

with State and local interests, it is difficult to acknowledge fully the many organizations and individuals who have contributed. Here it is only 

possible to mention a few. 

From the beginning, the Oregon Department of 

Environmental Quality has been a constant advisor and contributor. Many members of the 

agency have enthusiastically provided support, 

and we wish to especially acknowledge Jack 

Weathersbee, Warren C. Westgarth, and Glen D. 

Carter. The U.S. Army Corps of Engineers participated in the development of a reservoir model 

and also assisted financially in the development 

of the photo mosaic base. David M. Rockwood and 

George Holmes were largely responsible for the 

excellent cooperation of the Corps. 

Tom J. Lucus of the Columbia Region Association of Governments provided valuable insight 

and important information throughout the study. 

John D. Beaulieu, Oregon Department of Geology 

and Mineral Industries, assisted in the development of criteria for the erosion-potential map and 

was a constant source of geologic information. 

Fred A. Limpert, Bonneville Power Administration, aid.ed early in the development of the project 

through his excellent contacts with State and 

Federal agencies. 

High altitude photographs were provided by 

the National Aeronautics and Space Administration, NASA-Ames Research Center, Moffett 

Field, California. Arrangements for the photography were facilitated by the Environmental Remote Sensing Applications Laboratory (ERSAL) 

1 at Oregon State University and by Ernest H. 

M5 
Lathram, U.S. Geological Survey. ERSAL also 

provided financial assistance for the production of 

the photomosaic base. 

Richard Petersen of Portland State University 

was instrumental in the design and conduct of the 

algal study, and Lolita Carter, together with 

Douglas Larson, provided valuable aid in data interpretation. Joseph V. Hunter and Thomas J. 

Tuffey, both of Rutgers University, helped in the 

design and interpretation of work on dissolved 

oxygen and nitrification. Trace-metal analyses 

were made by Kam W. Leong and Raymond G. 

Havens of the Geological Survey. 

Invaluable aid in all phases of the project was 

given by the Oregon District Office of the U.S. 

Geological Survey, under the direction of Stanley 

F. Kapustka. Individuals who became deeply involved with the project included David J. Lystrom, Alexander H. Gonsalves, Nyra A. Johnson, 

Frank A. Rinella, Joseph F. Rinella, and Timothy 

L. Miller. 

Thoughtful criticisms and suggestions concerning other circulars in this series were made by 

several members of the Geological Survey including John H. Feth, Robert M. Beall, Vance C. 

Kennedy, Keith V. Slack, and Phillip E. Greeson. 

The project was initiated in response to a recommendation to the Geological Survey by the 

Advisory Committee on Water Data for Public 

Use. Our special thanks go to the Advisory Committee's Ad Hoc Working Group on River-Quality 

Assessment which provided constant encouragement, positive criticism, and manuscript review. 

During the study, the members of the group included Howard B. Brown, Robert A. Canhan, Edward J. Cleary, Laurence R. Jahn, John E. Kinney, Walter A. Lyon, John A. Roller, and Clarence J. V elz. 

Clarence V elz was also instrumental in the design and conduct of the dissolved-oxygen modeling study, and he continually provided encouragement, insight, and professional criticism of 

high excellence on all elements of the project. 

INTRODUCTION 

Today there is an urgent need for comprehensive resource assessment in most river basins of 

the United States. In response to this need, many 

planning groups have prepared reports that project future demands for water supply, wastewater treatment, and other services, and suggest 

possible alternatives for meeting the demands. 

Implicit in these reports is the acceptance of 

economic and population growth, but in a manner 

assumed consistent with some desired level of 

land and river quality. 

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, the impact-assessment link represents a 

stumbling block to the overall process. The difficulty in appraising impacts results from (1) absence of a rational framework for structuring 

such work, (2) lack, poor development, and misapplication of assessment methods, and (3) scarcity of reliable data. The concept of river-quality 

assessment as developed and used in the present 

study provides a mechanism for overcoming each 

of the three deficiencies. 

In 1964, the Bureau of the Budget (now Office 

of Management and Budget in the Executive 

Office of the President), issued Circular A-67 

which designated the Department of the Interior 

as the lead Federal agency in water-data acquisition and prescribed creation of Federal and nonFederal committees to assist the Geological Survey (Interior's designated bureau) in coordinating 

the designated functions. The non-Federal committee was officially named the Advisory Committee on Water Data for Public Use. 

Several years ago, the Advisory Committee 

voiced concern at the lack of suitable information 

for adequate river-basin planning and, in 1971, 

formally recommended that the Geological Survey conduct a pilot, interdisciplinary riverquality study. The recommended objectives were 

(1) to define a practical framework for conducting 

comprehensive river-quality assessments; (2) to 

determine the kinds and amounts of data required to adequately assess various types of 

river-quality problems; (3) to develop techniques 

for evaluating such data and for presenting it so 

as to promote better public understanding of its 

significance; (4) to develop and document methods 

for assessing planning alternatives in terms of 

potential impacts on river quality; and (5) to 

apply the framework, data programs, and 

methods to assess the critical river-quality problems of a major river basin. 

The Geological Survey responded to the comM6 
mittee's recommendation by starting in January 

1973 a prototype river-quality assessment study 

in the Willamette River basin, Oregon. The Willamette River basin was selected for several reasons. First, there was an excellent base of 

background data, particularly on hydrology. Second, 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 Rept., 1969). Thus, the 

study could evaluate existing planning alternatives to provide a realistic test of assessment approaches. Fourth, the Willamette was the largest 

river in the Nation on which all major pointsource discharges received secondary wastewater 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 could include 

appraisal of the factors to which past improvement was attributed, in addition to evaluating 

the factors that needed to be managed to maintain or improve the quality. 

This report summarizes both the development 

of a framework for conducting intensive riverquality assessments and the results obtained 

from applying the framework to four riverquality problems in the Willamette River basin, 

Oregon. The assessed problems were: (1) the effect of population and industrial growth and resulting waste discharges on dissolved oxygen 

(DO), (2) the potential for nuisance algal growth, 

(3) the possibility of trace-metal accumulation in 

river-bottom sediments, and (4) the potentially 

harmful effects on land and river quality of accelerated erosion resulting from intensified land use. 

Detailed results for each element of the study 

are presented in lettered chapters in Geological 

Survey Circular 715. To acquaint the reader with 

the series, the brief titles of the chapters are: 

A. A Practical Framework for River-Quality 

Assessment (Rickert and Hines, 1975) 

B. Formulation and Use of Practical Models 

(Hines and others, 1975) 

C. Project Development (Rickert and others, 

1976) 

D. Hydrologic Analyses (Hines and others, 1976) 

E. General Aspects of Streamflow and Reservoir 

Release Modeling (Jennings and others, 

1976) 

F. A Synoptic Survey of Trace Metals (Rickert 

and others, 1976) 

G. The Potential for Algal Problems (Rickert and 

others, 1976) 

H. A Reservoir-System Model (Shearman, 1976) 

I. Dissolved-Oxygen Conditions (Hines and 

others, in preparation) 

J. A Dissolved-Oxygen Model (Hines and others, 

in preparation) 

K. Planning Implications of Dissolved-Oxygen 

Conditions (Rickert and others, in preparation) 

L. Analysis of Erosional Processes and Problems 

(Brown and others, in preparation) 

These circulars are referred to as lettered chapters throughout the present report, and complete 

citations are given in the reference section for 

those published or in press. 

RIVER-QUALITY ASSESSMENT AND ITS RELATION TO 

RIVER-BASIN PLANNING 

River-quality problems stem basically from two 

factors, the unique hydrology of a river basin and 

man's development and use of the land and water 

resources. Depending on the interrelation of these 

factors, a wide variety of quality problems can 

result. Each river basin, therefore, is unique, and 

it follows that each one must be subjected to individual and intensive river-quality assessment to 

provide a proper basis for judicious management 

of the land and water resources. 

In the broadest context, river-quality assessment is a problem-oriented approach for developing information that is appropriate and adequate 

for sound resource management. In a more specific sense, river-quality assessment is the science 

and art of identifying the significant resource 

problems, defining them with adequate relevant 

data, and developing methods for evaluating the 

impacts of planning alternatives on each specific 

problem. In order to predict the consequences of 

any plan of action, it is essential to have a fundamental understanding of cause-effect relationships. Assessment, therefore, extends far beyond 

basic data on the physical, chemical, and biological quality of water to measurement of pollution 

sources and the prevailing hydrologic conditions 

that cause the observed effect. When, by scientific 

analysis, cause-effect relationships are defined 

and verified, then assessment becomes a powerful 

M7 
predictive tool by which alternative plans of action can be evaluated. Such evaluations then become a rational guide for the planner and the 

decision-maker in establishing priorities. 

In keeping with this philosophy, the approach 

developed for the Willamette study includes the 

seven steps outlined across the bottom of figure 1. 

Each of these steps was fully described in 

Chapter A. 

Within figure 1, the planning components are 

outlined by solid lines to symbolize a more or less 

standard process, whereas the assessment components are portrayed in dashed lines to represent an undeveloped potential. To place the figure 

in perspective, it must be noted that river quality 

is but one of many factors that decisionmakers 

consider in choosing among alternative plans. 

River quality is a single component of the 

natural-resource system, which, in turn, is only 

one aspect of the socioeconomic-politicalenvironmental structure of river-basin management. In many basins, demographic and economic 

uncertainties may be greater than the river0 3 ~ DEVELOPMENT 0 F DESCRIPTION OF z PUBLIC POLICY 

z AND OPPORTUNTITIES 

~ LONG-RANGE GOA LS AND PROBLEMS ..J 

/4 0.. 

z 

u; 1 ~ 2 a:l IDENTIFICATION EVALUATION OF a: 

w AND DESCRIPTIO N EXISTING 

~ OF NEEDS INFORMATION 

a: , 

r.;--------, 

r.------, 1

2 ANALYSIS OF I 

1-z 11 l.--.--.1 RIVER HYDROLOGY I ~I DELINEATION OF II L ___ ] ____ J 

~ I RIVER-QUALITY 

quality uncertainties. Such a situation actually 

increases the need for assessment, because a 

sound understanding of river quality provides a 

starting point for systematic evaluation of the 

socioeconomic and political options and of the 

technical alternatives for control of land and 

water resources development. 

PHYSICAL SETTING 

The detail provided here to describe the physical setting of the Willamette River basin offers an 

illustration of the types and scope of data required for designing a river-quality assessment. 

The manner of presentation was considered more 

effective than a simple outline of data needs but is 

offered with the recognition that key factors and 

data availability may vary from basin to basin. 

The Willamette River basin, a watershed of 

nearly 11,500 mi2 (29,800 km2) (fig. 2), contains 

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 

5 6 

FORMULATION OF PLANNING ALTERNATIVE 

PLANS FOR AND 

MANAGEMENT GROWTH AND 

DEVELOPMENT DECISIONS 

WI PROBLEMS I r.--- ----, 

~ L ______ J 1

3 

SELECTION OF l r-------- 1 

> ASSESSMENT METHODS 15 DATA ANALYSIS, I 

r:-------, 

1

6 FORECASTING I I IMPACTS OF I 

PLANNING I 

j L_-- - ----J I METHOD FORMULATION, 

~ 1 AND THE TESTING OF I :::> I PREDICTIVE 

0 ~--- ----H CAPABILITY I a: IDENTIFICATION ._ ________ J 

~ I COLLECTION, AND I 

ii: COLLATION OF 

REQUIRED DATA 

41 ALTERNATIVES ON I RIVER QUALITY I ._ __ l ___ _J ,7------, 

I COMMUNICATION 

OF RESULTS 

FIGURE 1.-The interrelation of river-quality assessment to river-basin planning. 

M8 
w 

~ 0 

u 

II 

INDEX MAP OF OREGON 

0 

I 

0 I 

10 

10 

I 

I 

20 MILES 

I 

30 KILOMETRES 

w 

0 

<( 

~ <( 

u 

FIGURE 2.-Willamette River basin Oreg., emphasizing the main stem, principal tributaries, and major 

reservoirs. 

M9 
economy based on timber, agriculture, industry, 

and recreation and contains extensive fish and 

wildlife habitats. 

The basin is roughly rectangular, with a 

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

an east-west width of 75 mi (120 km). Elevations 

vary from less than 10 ft (3 m) near the mouth 

of the Willamette River to 450 ft (140 m) on 

the valley floor near Eugene and to more than 

10,000 ft (3,050 m) in the Cascade Range. Average annual precipitation in the basin is 63 in. 

(1,600 mm). 

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 timber land, 

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. 

GEOLOGIC OVERVIEW 

On the basis of physiography and geology, the 

Willamette River basin can be divided into three 

north-south provinces: The Cascade Range, the 

Coast Range, and the interlying Willamette Valley (Willamette Basin Task Force, Appendix A, 

1969). 

The volcanic rocks that compose the Cascade 

Range can be divided into two major groups. The 

older group consists of basalt and andesite together with volcanic debris. These rocks have 

been folded, faulted, and extensively altered. The 

younger rocks, which form the High Cascades, 

are derived from more recent basaltic and andesitic lava flows. 

The mountains and foothills of the Coast Range 

are formed largely by volcanic rocks and by 

marine sedimentary rocks derived from them. 

The older volcanic rocks, consisting of basalt 

flows and volcanic debris, are interbedded with 

continental sedimentary rocks. The marine 

sedimentary rocks consist of sandstone, shale, 

and mudstone. 

The Willamette Valley is an elongated alluvial 

lowland framed by resistant volcanic and 

sedimentary rocks. Much of the valley is covered 

by sandy to silty terrace deposits that settled from 

water ponded in a great glaciofluvial lake. Most of 

the materials in these deposits appear to have 

originated from upstream areas of the Columbia 

River basin (Glenn, 1965). The alluvial deposits 

that border existing rivers were derived largely 

from the surrounding mountains. These deposits 

consist of intermingled layers of clay, silt, sand, 

and gravel. 

WILLAMETTE RIVER MORPHOLOGY 

The main stem Willamette River is formed by 

the confluence of the Coast and Middle Forks near 

Eugene (fig. 3) and flows for 187 mi. (301 km) to 

the Columbia River. Over this distance the channel bed drops from an elevation of 435 ft. (133 m) 

to slightly below mean sea level. The main stem 

comprises three distinctive reaches whose physical characteristics govern the hydraulics of flow 

and therefore the patterns of deposition, channel 

scour, and sediment transport. 

The Upstream Reach (fig. 3 and table 1), extending for 135 mi (217 km) from Eugene to above 

Newberg, is characterized by a meandering 

channel. The river is shallow and the bed is composed almost entirely of cobbles and gravel which, 

during summer, are covered with biological 

growth. During low-flow conditions, average 

stream velocity in the Upstream Reach is about 7 

times that of either of the two downstream 

reaches (table 1). During floods, velocities are sufficiently high to transport large quantities of 

cobbles and gravel as bedload. Morphologically, 

this upstream section of the Willamette River is 

an ~~eroding" reach. 

The Newberg Pool extends for 25.5 mi (41.0 

km) from above Newberg to the Willamette Falls. 

Hydraulically, the deep, slow-moving Pool can be 

characterized as a large stilling basin behind a 

weir (Willamette Falls). As evidenced by the elevation profile (fig. 3), average low-flow velocity 

(table 1), and the presence of fine bottom sediments, the Pool is a depositional 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 ft 

(12 m) deep navigation channel from the mouth to 

about river mile (RM) 14. During the summer 

low-flow period, net downstream movement is 

slow, 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) where, depending on hourly changes in tideand river-stage conditions, Willamette River 

water may move downstream, or Columbia River 

water may move upstream. Owing to morphologiM10 
400 

300 r-+-~-+-;~~~ 

0 

I 

0 

'• 

(A) 

187 (301 kml 

3 135 mi (217 km) 

30 MILES I 

I 

50 KM 

(B) 

SEA 200 

100 ~=t=t=l==r=t=t=i=~=t=t=t=i~==F=f=f=l=lf~=r~-,-,--r-.-~,-~~~~_,_j LEVEL~~~~~~~~-1~50-L~-L-L~~~~~-1~00~~~~-4~~~~~5L0-L-L~~~~~~~~ 

DISTANCE, IN RIVER MILES ABOVE MOUTH 

300 200 100 

DISTANCE, IN RIVER KILOMETRES ABOVE MOUTH 

FIGURE 3.-Willamette River, Oreg. A, Distinctive hydrologic reaches. B, Elevation profile. 

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

[Characteristics refer to summer low-flow conditions of6xl03 fP/s at Salem] 

Representative Approximate 

Reach Approximate 

(see Length bed slope 

fig. 3) (mil (ft./mil Bed material 

Tidal 26.5 <0.1 Intermixed clay, sand, and 

Reach (1) gravel. 

Newberg 25.5 .12 Intermixed clay, sand, and 

Pool (2) gravel with some cobbles. 

Upstream 135 2.8 Mostly cobbles and graveL ___ Reach (3) 

1Calculated by volume displacement method using channel cross-sectional data. 2Calculated from dye study by Geological Survey <Harris, 1968>. 

Mll 

midchannel Average traveltime 

water depth 

(ftj 

velocity in reach (ft/s) (days) 

40 10.16 10.0 

25 10.40 3.9 

7 22.9 2.8 

0 

METRES 

160 

120 

80 

40 
cal characteristics and the hydraulic conditions, 

the subreach between RM's 10 and 3 is the primary depositional area of the Willamette River system. 

RESERVOIRS AND HISTORICAL 

STREAMFLOW PATTERNS 

There are 11 major reservoirs in the Willamette River basin (see fig. 2) with a combined 

usable capacity of nearly 1.9 million acre-ft (2,300 

hm3 ) (see Chapter H). The reservoirs are designed 

for multipurpose use, but their primary legal 

function is the maintenance during summer of a 

minimum navigable depth in the Willamette 

River (Willamette Basin Task Force, Main Rept., 

1969). The required minimum flow for navigation 

is 6,000 ft3/s (170 m3/s) at Salem. Other uses of 

the reservoirs and reservoir water include power 

generation, onsite recreation, flood protection, 

maintenance of adequate streamflow for anadromous fish propagation, irrigation, 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. 

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 4. 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 in the period 

between 1941 and 1949. However, it was not until 

operation of reservoirs on Cascade Range 

tributaries, beginning in water year 1953, that 

reservoirs had a significant impact on Willamette 

River flow. 

Reservoir regulation has had a profound impact 

on low flows in the Willamette River (Chapters D 

and H). Marked increases have occurred in the 1-, 

3-, 7-, 14-, and 30-day low flows during the post1953 period. Reservoir regulation also has curtailed 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. 

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 decision-making process. 

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

in January 1973. (See Rickert and others, 1975a 

and Chapter C.) The original concept was to use 6 

months for planning and for organizing field and 

laboratory programs, 15 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 the data collection into 

the fall of the second year. The study duration 

was thus expanded to 2¥2 years. 

In retrospect, 2¥2 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 periods of 

the annual cycle. In many river basins (including 

the Willamette), the low-flow, high temperature 

season is the critical time period for most riverquality problems (for example, dissolved-oxygen 

depletion). For such basins a study duration of2¥2 

years, together with a January start, provides for 

two summer field seasons. Specific critical problems may require assessment over longer periods, 

but initial assessments of immediate problems 

need to be completed as quickly as possible in 

order to be of value to the resource-planning process. As noted in Chapter A, reappraisals can then 

be made under reduced time pressures, while full 

scale updates can be scheduled on a periodic 

basis. 

M12 
100,000 

1000 

10,000 

100 

1000 

0 

0 100,000 z 

0 z u 0 w u en w a: en w a: c.. w 1000 en c.. w t- a: w t- w w u. ~ 

u u iii 10,000 al ::> ::> u u z 

w· ~ 

(.!) w· 

a: 100 (.!) 

<( a: I <( 

u I en u 

0 en 

0 

1000 

100,000 

1000 

10,000 

100 

FIGURE 4.-Willamette River discharge at Salem, Oreg., 1944, 1964, and 1973 

water years. Note the recurrent nature of the July, August, and September 

low-flow periods even after large-scale streamflow regulation began in 1953. 

M13 
MANPOWER 

The nature of river-quality problems requires 

an interdisciplinary, team-oriented approach. In 

the Willamette Study, the team was composed of 

scientists and of engineers experienced in river 

work and trained in the discipline categories of 

hydrology, sanitary chemistry, aquatic biology, 

mathematical modeling, and geology. The core 

team included four individuals having different 

training and professional backgrounds and five 

part-time aides. In addition, the project periodically used the talents of the Survey's research 

staffs and District offices, as well as the consultative, fieldwork, and laboratory services of scientists from several universities. Analytical work 

was done by the project team and by several 

Geological Survey laboratories. 

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 (table 2). These problems were then 

evaluated using published and unpublished data 

from the Oregon Department of Environmental 

Quality (1970), the U.S. Geological Survey 

(1962-73, 1964-73), and the STORET system of 

the U.S. Environmental Protection Agency 

(Sayers, 1971). Next, in conjunction with the resource agencies, the problems were ranked in 

order of their relative importance to resource 

management (table 2). 

Selection of project elements for this pilot assessment was completed by analyzing the priority 

list in terms of ability to produce useful information within the constraints of time, funding, and 

TABLE 2.-Existing or potential river-quality problems of the 

Willamette River basin, Oreg. 

Problem 

~:~:!:~~FeS:lo~:~~~n--====================== Dissolved-oxygen depletion----------------------

Algal-problem potential ------------------------ Trace-metal occurrence ________________________ --

Sanitary quality-------------------------------- Accelerated erosion ---------------------------- Riverbank esthetics ----------------------------

1 l=greatest importance; 3=least importance. 

Relative 

importance• 

3 

3 

1 

2 

1 

3 

1 

2 

Selected for present study 

X 

X 

X 

X 

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. The four rejected elements are discussed in 

Chapter C and suggestions are provided for several additional studies. 

Once the project elements were identified, it 

was clear that additional hydrologic information 

was needed to adequately assess the impact of 

planning alternatives on ~~dissolved-oxygen depletion" and Halgal-problem potential." 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 required the development of predictive mathematical models. The modeling approaches, data inputs, and results are described 

by Bennett (1975) and in Chapters E and H. No 

details of these modeling efforts are provided in 

this report, but brief mention is made of certain 

results. 

The following sections of the report describe the 

assessment methodology and the results attained 

for the four project elements. The descriptions are 

intended to provide only a summary of the individual studies. The interested reader may wish to 

consult the individual chapters for technical details and documentation. 

DISSOLVED-OXYGEN DEPLETION 

BACKGROUND 

Historically, maintenance of high DO concentration has been the critical problem in the Willamette River. During summer low-flow periods, 

the DO concentration in Portland Harbor often 

was 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 (Chapter I). The improvement has resulted from a reduction in the loading 

of point source 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 

M14 
to be the factor of highest priority in planning the 

Willamette's future. 

Today (1976), the Willamette is the largest 

river in the United States on which all pointsource discharges receive secondary wastewater 

treatment. The Willamette thus offers a unique 

opportunity to document the impacts of both secondary treatment and flow augmentation on the 

quality of a major river. 

STUDY 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 characteristic 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 stems from the fact that some riverquality models have not been based on sufficient 

data nor effectively applied to real planning and 

management situations. 

Because of past experiences, the Oregon DEQ 

was skeptical at the outset of the DO study that a 

mathematical model could be formulated for 

practical use. The project staff determined the 

reasons for skepticism and devised a framework 

for avoiding the potential pitfalls. The following 

summarizes the modeling framework from Chapter B: 

1. Select the simplest mathematical configuration capable of providing useful planning 

and management information. 

2. Model only the critical time period and river 

reaches of DO depletion. 

3. Carefully calibrate the model against one set 

of data and later verify it against a second 

set of completely new data. 

4. Conduct an intensive data-collection program 

to provide the needed data (see ~~Data Program"). 

5. Present all modeling results in an easy-tounderstand format. 

DATA PROGRAM 

Review of existing data indicated that an appreciable DO deficit occurs in the Willamette only 

below RM 86 and during the yearly low-flow 

period of July through August. The DO datacollection program was thus developed to formulate a mathematical model for simulating conditions below RM 86 for the critical summer period. 

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. Because 

the municipal and industrial waste-waters received secondary treatment, ultimate BOD 

(BODult) 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. A nitrification inhibitor 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 calculaM15 
tion of river-deoxygenation coefficients. Detailed 

channel-geometry data were assembled so that 

reliable reaeration rates could be calculated for 

each subreach of the river. Similarly, synoptic, 

in-river data on ammonia decay and nitrate generation were collected to permit calculation of nitrification rates on a reach-by-reach basis. 

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 

often observed owing to photosynthetic activity. 

Continuous-monitor records of DO and temperature were collected to estimate the impact of algal 

activity on river DO. 

DISSOLVED-OXYGEN REGIMEN 

DISSOLVED-OXYGEN PROFILES 

Basinwide secondary treatment has had a profound impact on the major deoxygenation processes and consequently on the DO regimen of the 

Willamette River. During the summer low-flow 

period of 1974, average daily DO concentrations 

met State standards for all reaches of the river at 

flow conditions between 6,500 and 7,000 ft3 /s 

(184 and 198 m3 /s) and water temperatures between 22° and 25°C (Celsius). 

Figure 5 compares the 1973 DO profile of the 

Willamette River to selected historical conditions 

for the summer low-flow period. In spite of the 

steady improvement in DO since 1944, the profiles do not reflect a simple, clearcut time trend. 

The reason is that circumstances, often undiscernable from the existing records, tend to 

obscure the short term trends. For example, the 

RIVER KILOMETRES ABOVE MOUTH 

w 

a: 

1-

:::i 8 

a: 

w 

0.. 

C/) 

~ 

<( 

a: 

(!) 6 

:::i 

.J 

~ 

~ 

z-

~ 4 

>-

X 

0 

0 

w 

> .J 

0 2 C/) 

(/l 

0 

Salem 

Willamette ,_Portland_, 

Falls Harbor 

50 0 

1934, 3000 ft3fs/ 

01~----------------~----------------~----------------~------------~----------------~ 

100 80 60 40 20 0 

RIVER MILES ABOVE MOUTH 

FIGURE 5.-Comparison of 1973 with historical DO profiles in the Willamette River 

for the summer low-flow period. (Historical data are adapted from Gleeson, 1972.) 

M16 
1971 DO profile generally is higher than the 1973 ing July-August 1974 was essentially the same 

profile despite the fact that certain secondary as that presented in figure 5 for 1973. 

treatment plants were not in operation until 

1972. This apparent anomaly can be explained by NITRIFICATION 

(1) higher summertime flows during 1971 and (2) During the summers of 1973 and 1974, nitrifithe fact that dur..ing 1971, certain pulp and paper cation was the dominant control on DO in the 

mills were on a waste management program shallow, swift-flowing subreach between RM's 85 

whereby primary effluents were stored during and 55. Examination of historical data indicates 

summer and released to the river during the high that this reach began to receive appreciable amflow conditions of fall, winter, and spring. monia loading from a pulpmill in 1956. 

Figure 5 provides a comparison of the 1973 DO Dissolved-oxygen data from the 1950's and 1960's 

profile to profiles determined at similar flows dur- are sketchy, but suggest that nitrification did not 

ing 1956 and 1959. In 1956, there was a DO- become a significant oxygen sink until the advent 

concentration ((plateau" between Salem and of secondary treatment at pulp and paper mills. 

Newberg, followed by a sharp decrease in DO Secondary treatment incurred the use of amthrough the Newberg Pool. These conditions were monium hydroxide for neutralizing wastewaters 

consistent with large loadings of BOD in the prior to treatment and resulted in continuous disvicinity of Salem, a rapid traveltime between charge of effluents to the Willamette rather than 

Salem and Newberg, and a large amount of the previously used program of summer lagooncarbonaceous deoxygenation in the slow-flowing ing and winter discharging. 

Newberg Pool. Figure 6 shows the average instream concenThe 1959 data show an increase in DO con- trations of ammonia nitrogen (NH4 -N), nitrite 

centration below Willamette Falls and a sharp nitrogen (N02-N) and nitrate nitrogen (NOa-N) 

decrease in DO through the Tidal Reach. These from RM 120 to 7 for August 12-14, 1974. The 

observations were consistent with known re- curves reflect a prominent ammonia source near 

aeration at the falls, inflow of cool water of high RM 116 and rapid instream oxidation of ammonia 

DO content from the Clackamas River, and the to nitrite and nitrate downstream to RM 86. Durdecay of carbonaceous wastes which entered the ing the study period, the subreach below RM 86 

river just below the falls and throughout Portland received about 5,800 lb/d (2,630 kg/d) ammonia 

Harbor. nitrogen from upstream sources, 16,200 lb/d 

The 1973 profile shows a rapid decrease of DO (7,350 kg/d) from an ammonia-base pulp and 

from RM 86 to Newberg, a DO ((plateau" in the paper mill at RM R5 and about 1, 700 lb/d (770 

Newberg Pool, a DO increase over Willamette kg/d) from a municipal sewage plant at RM 78. 

Falls, a gradual decline in DO between RM's 24 The instream data show a rapid conversion of the 

and 13, a sharp decrease in DO between RM's 13 ammonia to nitrite and nitrate between RM's 85 

and 5, and recovery of DO below RM 5. The DO and 55. The deep, relatively slow moving Newdecrease between RM 86 and Newberg contrasts berg Pool begins at RM 52 and, although residual 

with a ((plateau" in 1956 and results from nitrifi- ammonia entered this reach, no further nitrificacation that did not occur at the earlier date. The tion could be detected from nitrogen-species 

1973 DO ((plateau" in the Newberg Pool indicates analysis. 

that carbonaceous deoxygenation is now occur- The occurrence of nitrification in a shallow, 

ring at a rate slow enough to be balanced by DO surface-active reach and the contrasting absence 

inputs from atmospheric reaeration. The DO de- in a deep, slow-moving reach is consistent with a 

crease between RM's 24 and 13 is consistent with recent hypothesis proposed by Tuffey, Hunter, 

measured river loads of ultimate BOD, but the and Matulewich (1974). According to the 

sharp decrease between RM's 13 and 5 cannot be hypothesis, nitrification in shallow, swift-flowing 

accounted for by known sources of BOD. (See sec- reaches would occur by virtue of an attached, 

tion entitled ((Undetermined Oxygen Demand.") rather than a suspended community of nitrifying 

The recovery of DO below RM 5 results from the organisms. To test the hypothesis, enumerations 

admixture of high-quality water from the Colum- were made of nitrifying bacteria in water samples 

bia River. The DO profile of the Willamette dur- and in biological slimes scraped from bottom 

M17 
RIVER Ml LES ABOVE MOUTH 

Albany Salem Newberg 

120 86 50 

Willamette 

Falls 

26.5 1

, ____ Portland 

17 13 

Harbor -; 

1.4r-~--~-.-------,.----L---,---L---,~-------.--~ 

1.2 

r--

,. ... "' ... ,,-------........................... ..... 

........... .......... N03-N __ _ 

----

Discharge at Salem = 6760 tt3/s 

.2 

2 4 6 8 10 

TIME OF PASSAGE, IN DAYS 

FIGURE 6.-Inorganic nitrogen concentrations in the Willamette River during midAugust 1974. 

rocks. Nitrosomonas concentrations were <1 

most probable- number (MPN)/ml in all water 

samples. In slimes, Nitrosomonas concentrations 

were <1 MPN/mg above RM 86 and 1-4 MPN/mg 

in samples collected between RM's 85 and 55 (the 

active zone of nitrification). Shortly below RM 55, 

the deep Newberg Pool begins, and few bottom 

rocks are available for attachment of biological 

slimes. N itrobacter enumerations were also made 

and in the zone of nitrification ranged from <1 to 

4 MPN/m1 in water samples and from 6-50 

MPN/mg in slimes. The combined bacteriological 

data thus support the hypothesis that nitrification occurred in slimes attached to rocks rather 

than in flowing water. (See Chapter I for elaboration.) 

Based on observed river concentrations of nitrate in the river (fig. 6), a rate of nitrification was 

calculated for the affected subreach. Assuming 

first-order decay, the rate, kn (log10), was about 

0.7/d (see Chapter I for discussion). Applying this 

rate to the measured loadings of ammonia indicates that, for the August 12-14 period, nitrification removed about 55,000 lb/d (25,000 kg/d) DO 

from the 30-mi (48-km) subreach. This satisfied 

demand was responsible for most of the decrease 

observed in DO concentration (fig. 5). 

CARBONACEOUS DEOXYGENATION 

Present-day BOD-loading patterns and rates of 

exertion contrast sharply with those observed 

during the mid-1950's. 

BOD LOADING 

During the dry-weather period of 1954, the estimated point-source loading ofBODult to the Willamette River was approximately 350,000 lb/d 

(160,000 kg/d). This total included chemical demands resulting from sulfite wastes, soluble and 

suspended carbonaceous demands from pulp and 

paper mills, and the carbonaceous demands of 

raw sewage and primary effluents. 

In contrast, the point-source BODult loading 

during August 1974 was about 92,000 lb/d 

(42,000 kg/d) (table 3). The decrease from 1954 

resulted from secondary treatment of all carbonaceous wastes, chemical recovery of sulfite 

wastes, and the routing of sewage effluents from 

metropolitan Portland into the Columbia River 

instead of the Willamette. 

M18 
TABLE 3.-Dry-weather 1974 ultimate BOD loading, 

Willamette River, Oreg. 

[see Chapter I] 

Source Loading 

{lb/day) Percent 

Nonpoint -------------------------- 77,100 46 

Point ------------------------------ Municipal______________________ 37,600 22 

Industrial---------------------- 54,400 32 

Total ------------------------ 169,100 100 

Table 3 shows the distribution of BODult loading between point and nonpoint (diffuse) sources 

for July-August 1974. Most of the estimated loading from diffuse sources represents natural 

background demand from essentially pristine 

streams (see Chapter 1). Thus, during the summer 

low-flow period, only about one-half the observed 

BODult loading to the Willamette is amenable to 

removal by future pollution-control programs assuming that such programs could provide total 

removal. 

CONCENTRATIONS AND RATES 

During the low-flow period of 1954, 5-day BOD's 

averaged about 2.5 mg/1 at sites immediately 

below large waste-water outfalls, whereas in 

197 4 the concentration at the same sites was 

about 1.0 mg/1. This decrease resulted only partly 

from the noted reduction in waste water loading. 

The decrease also resulted from a treatmentcaused change in the biochemical nature of 

waste-water materials, which in turn caused a 

decrease in the river rates of carbonaceous 

deoxygenation. (See Chapter 1.) In 1954, the k 1 

(log10 ) value for all river BOD samples was 0.1/d 

or greater (Velz, 1951). In contrast, measured k 1 

values in 1974 were clustered around 0.04/d. This 

means that in 1954, a minimum of about 68 percent of BODult was exerted in a river-water sample in 5 days, whereas in 1974 the comparative 

value was 37 percent (see Velz, 1970, for discussion of BOD exertion). This comparison underscores the need for determining k 1 values and 

BODuu (rather than BOD5 alone) as a basis for 

accurately modeling DO under conditions of secondary treatment. 

During both 1973 and 1974 the inriver concentrations of BODult averaged about 2.5 mg/1. 

DISSOLVED-OXYGEN MODELING 

The model chosen for the study was the one 

developed and used for more than 30 years by 

C. J. Velz. The basic model (Velz, 1970) is applicable to conditions of steady (invariable), 

nonuniform (changing cross-sectional geometry), 

plug (nondispersive) flow. The computer program 

as formulated for the present study is called the 

WIRQAS (Willamette Intensive River Quality 

Assessment Study) Model. 

The model was calibrated against 1974 

streamflow and temperature conditions and verified against the slightly lower flow and higher 

temperature conditions of 1973. (See Chapter J 

for discussion.) For conditions representing 1974 

summer low flow, the model indicates that an 

oxygen demand of 164,000 lb/d (74,000 kg/d) was 

satisfied between RM's 86 and 5. Of the total, 

about 22 percent resulted from background 

carbonaceous-oxygen demand, 28 percent from 

point-source carbonaceous demand, 34 percent 

from point-source ammonia, and 16 percent from 

an undetermined demand in Portland Harbor (see 

HUndetermined Oxygen Demand"). 

PLANNING IMPLICATIONS 

As an aid to river-quality planning, the WIRQAS Model has been used to test management 

alternatives concerning (1) BOD loading, (2) ammonia loading, (3) low-flow augmentation, and (4) 

the effects of possible removal or reduction of the 

undetermined oxygen demand (Rickert and 

others, 1975b, and Chapter K). This section describes the major implications of tested alternatives by comparing measured DO profiles with 

profiles generated by the verified model. A fact 

the reader should bear in mind in examining the 

following illustrations (figs. 7-11) is that, for ease 

of presentation, the DO profiles are plotted as a 

function of river location. Thus the slopes of 

curves in specific subreaches do not represent the 

actual rates at which oxygen is added to or lost 

from the river. For example, the profiles in figures 

7-11 suggest a rapid rate of oxygen depletion 

below Willamette Falls. Actually, the steepness 

of the curves is caused by the slow time-of-travel 

in the Tidal Reach (see table 1) rather than by an 

accelerated rate of oxygen depletion. 

BOD LOADING 

The effect of BOD loading on summertime DO 

is reflected in figure 7. The curve labeled 100 percent represents the average DO profile of the 

river at the flow, water temperatures, ammonia 

M19 
RIVER KILOMETRES ABOVE MOUTH 

Salem Newberg 

Portland 

1- Harbor -1 

0 

t5 90 

i= 

<( 

a: 

::::> 

1-

<( 

VJ 

~ 80 

(!) 

>-

X 

0 

Cl 

w 

> 6 70 VJ 

VJ 

iS 

1-

z 

w 

() 

a: 

~ 60 

100 

EXPLANATION 

----- State DO standards 

80 60 40 20 0 

RIVER MILES ABOVE MOUTH 

FIGURE 7 .-Dissolved-oxygen profiles for selected percentages of the measured pointsource BOD loading during mid-August 1974. Flow and ammonia loading held constant at observed levels. 

loading, and BOD loading actually measured during the low-flow, steady-state period of midAugust 1974. The upper and lower curves represent the predicted DO profiles at 50 percent and 

200 percent of the measured point-source BOD 

loading with all other variables held constant at 

observed levels. These curves are calculated on 

the basis that all point-source BOD receives secondary treatment and decays at rates of 0.06/d 

above RM 55 and 0.03/d below this point. 

The upper curve in figure 7 indicates that only 

a slight improvement in DO can be obtained by a 

50 percent decrease of BOD loading from each 

point source. The predicted increase in DO would 

be <5 percent of saturation at the bottom of the 

Newberg Pool (RM 28) and 5 percent at RM 5, the 

low DO point in the river. 

In contrast, a doubling of BOD loading from 

each point source would depress DO by 5 percent 

of saturation at RM 28 and by 10 percent at RM 5. 

This decrease in DO would cause violation of the 

noted State DO standard in the subreach between 

RM's 62 and 50. 

Figure 8 compares the DO profile observed in 

mid-August 1974 with the predicted profile assuming a BOD5 standard of 10 mg/1 for all municipal effluents. Such a standard, supposedly attainable by high-level secondary treatment, is 

being considered by Oregon. Application of the 10 

mg/1 standard to 1974 conditions would decrease 

municipal summertime loading of BODutt to the 

Willamette from 37,600 to 17,400 lb/d (17,100 to 

7,900 kg/d). The largest individual decrease 

would be about 7,000 lb/d (3,000 kg/d) at Salem 

(RM 78). The modeling results (fig. 8) indicate 

that, over the investigated reaches, the reduced 

loading would have no effect on river DO. The 

lack of an effect stems from (1) the small reduction attainable in total loading of BODult (about 

12 percent; see table 3 ), (2) the low rates at which 

BODult is exerted in the river, and (3) the locations within the basin of the largest municipal 

wastewater treatment plants (see Chapter 1). 

AMMONIA LOADING 

Figure 9 illustrates the effect of ammonia loading 

M20 
RIVER KILOMETRES ABOVE MOUTH 

Z90 

0 

i= 

<(' 

0: 

:::> 

1-

<( 

en 

ffi 80 

(!) 

> X 

0 

0 

w 

> 6 70 en 

en 

0 

Newberg 

Portland 

1- Harbor ... I 

0 

1-

z 

w 

() 

EXPLANATION 

-Observed 

a: 

~ 60 ~ Predicted for a BODs municipal 

effluent standard of 10 mg/1 

-----State DO standards 

100 80 60 40 20 0 

RIVER Ml LES ABOVE MOUTH 

FIGURE B.-Dissolved-oxygen profiles: observed mid-August 1974 and predicted for a 

BODs municipal effluent standard of 10 mg/1. Flow and ammonia loading held constant at observed levels. 

on summertime DO in the Willamette. Compared 

to the observed DO profile (the 100 percent 

curve), a 50 percent reduction in ammonianitrogen loading from each point source would increase the DO by 7 percent of saturation near the 

bottom of the Upstream Reach (RM 60), by 5 percent at RM 28, and by <5 percent at RM 5. In 

contrast, a doubling of ammonia-nitrogen loading 

in each point source would decrease the DO by 13 

percent at RM 60, by 11 percent at RM 28, and by 

7 percent at RM 5. These results illustrate two 

important points. First, ammonia loading has its 

greatest effect on DO in the active zone of nitrification between RM's 85 and 55. Thereafter, 

measurable nitrification ceases to occur and the 

upstream effects of the process are gradually diminished by atmospheric reaeration. Second, 

comparison of figures 7 and 9 indicates that 

point-source ammonia loading has a greater influence on Willamette River DO than pointsource BOD loading. At the observed relative 

point-source loadings (43,000 lb/d, or 19,500 kg/d 

ammonia-nitrogen; 92,000 lb/d, or 42,000 kg/d 

BODultl), this occurs primarily as a result of(1) the 

greater oxygen demand per unit weight of ammonia as compared to the organic matter in secondary effluents and (2) the much greater rate at 

which ammonia is oxidized Ckt = 0.03 to 0.06/d; kn 

= 0.7/d) between RM's 85 and 55. 

The upper curve in figure 9 shows the impact 

of applying a standard of 10 mg/1 ammonianitrogen to all municipal and industrial effluents. 

Most of the ammonia that enters the Willamette below RM 86 is discharged from a large 

pulp and paper mill at RM 85 (see ~~Nitrification"). Control of ammonia from this one source 

would greatly reduce the impact of nitrification 

on the DO regimen of the river. 

LOW-FLOW AUGMENTATION 

The effect of flow augmentation on DO is illustrated in figure 10. The observed flow at 

Salem during mid-August 1974 was 6,760 ft3/s 

(191 m3/s). For comparison, computed DO profiles 

are presented for Salem flows of9,000, 5,000, and 

M21 
RIVER KILOMETRES ABOVE MOUTH 

z 

0 

j:: 

<( 

a: 

:::> 

1-

<( 

90 

Cl) 80 

z 

w 

(!) 

> 

X 

0 

0 

~ 70 ...1 

0 

Cl) 

~ 

0 

1-

z 

w 

~ 60 w 

0.. 

100 

EXPLANATION 

-----State DO standards 

80 60 40 20 

Portland 1 1- Harbor-! 

0 

0 

RIVER MILES ABOVE MOUTH 

FIGURE 9.-Dissolved-oxygen profiles for a hypothetical effluent standard of 10 mg/1 

ammonia-nitrogen and for selected percentages of the measured point-source ammonia loading during mid-August 197 4. Flow and BOD loading held constant at 

observed levels. 

3,260 ft 3/s (255, 142, and 92 m3/s). The latter 

value is near the lowest minimum monthly flow 

ever recorded for July under natural (nonaugmented) conditions (Velz, 1951). Predictions from 

a deterministic model (Chapter H) indicate this 

flow would have occurred during July of the unusually dry year of 1973. 

The impact of flow augmentation is marked. At 

a flow of 3,260 ft3/s (92 m3/s), the 1974 BOD and 

ammonia-nitrogen loadings would cause violation of State DO standards by a wide margin at 

most locations. The predicted DO saturation 

levels at 3,260 ft3/s (92 m13/s) are nearly 30 percent 

less than the observed values (6,760 ft3/s, or 191 

m3'/s) at RM's 60, 28, and 5. 

At a flow of 5,000 fe/s (142 m3/s), the State DO 

standard would have been violated between RM's 

67 and 50 and just have been met in the Newberg 

Pool and in the lower end of Portland Harbor. 

In evaluating increased flow augmentation it 

should be recognized that improvements in quality are less dramatic as the DO profile is raised 

toward the level of saturation. Thus, augmentation of flow to 9,000 ft3

/s (255 m3/s) would cause 

only a relatively small improvement in percent 

DO saturation. In fact, for conditions observed 

during August 1974, it appears that augmentation to discharges above 7,000 ft'3

/s (198 m3/s) 

would provide little incremental increase in DO. 

Nevertheless, under future conditions, augmented flows in excess of 7,000 ft3

/s (198 m3'/s) (if 

feasible) might be a desirable alternative to expensive, energy-consuming, advanced wastetreatment processes. 

Figure 11 illustrates the combined effects of 

nitrification and flow augmentation. Curve B is 

the average DO profile observed during the 

steady, low-flow period of July-August 1973. 

Curve D is the predicted DO profile at a flow of 

3,260 ft:3/s (92 m3/s) and the observed ammonia 

loading. In comparing curves Band D, note that 

without augmentation, the State DO standards 

M22 
RIVER KILOMETRES ABOVE MOUTH 

Newberg 

Portland 

1- Harbor •1 

0 

z 

0 

i= 

<( 

a: 80 ::> 

1-

<( 

en 

z 

w 

(.!) 

> 

X 

0 60 

0 

w 

> ..J 

0 

en 

en 

0 

1-

z 

w 

() 

([. 

w 

0.. 

EXPLANATION 

----- State DO standards 

20L---------~--------L---------~--------~------~ 

100 80 60 40 20 0 

RIVER MILES ABOVE MOUTH 

FIGURE 10.-Dissolved-oxygen profiles for selected flows with BOD and ammonia loadings held constant at levels measured during mid-August 1974. Observed flow was 

about 6,760 fP/s. 

would have been violated at most points in the 

river. Curves A and C represent predicted DO 

profiles at the same two flows, but with 

ammonia-nitrogen loading reduced to 10 mg/1 in 

all point-source discharges. With such an effluent 

limitation, the DO profile predicted at 6,000 ft3/s 

(170 rrl/s) is considerably above the observed 

profile (curve B) throughout most of the river. 

However, curve C portrays the most important 

finding for 1973 conditions. Even with complete 

secondary treatment and a reasonable limitation 

on ammonia loading, low-flow augmentation 

would be necessary to achieve DO standards in 

the Newberg Pool and in the Tidal Reach. 

Figures 7 to 11 indicate the value of the 

WIRQAS model in evaluating planning alternatives. The calculations illustrated in these figures 

were based on the channel morphology, the 

sources of pollution, and the sources of flow augmentation that occurred during 1973 and 1974. 

However, the WIRQAS model can be readily 

adapted to evaluate a wide variety of new situations, including changes in the spatial distribution of inputs and in channel morphology. The 

predicted DO profiles in this report represent a 

small part of an extensive series which has been 

developed as an aid to planners and decisionmakers. 

UNDETERMINED OXYGEN DEMAND 

During 1970, benthal respirometer studies 

(John Sainsbury, written commun., 1970) of the 

lower Willamette River documented a benthaloxygen demand of27,000 to 54,000 lb/d (12,000 to 

24,000 kg/d) in the subreach between RM's 13 and 

7. The river at that time still received some raw 

sewage in the form of combined sewer overflows 

and a moderate loading of fibers and other settleable solids from pulp and paper mills. Because 

these sources of solids were largely controlled by 

1972, it was anticipated that the benthal demand 

would be greatly reduced by 1974. However, durM23 
RIVER KILOMETRES ABOVE MOUTH 

z 

0 

;:: 

<( 

~ 80 

1-

<( 

(I) 

z 

w 

(!) 

> X 

0 

0 

w 

> ...J 

0 

(I) 

(I) 

0 

~ 40 w 

u 

a: 

w 

a.. 

EXPLANATION 

----- State DO standards 

Newberg 

Portland J 1- Harbor 1 

0 

20~--------~--------~--------~--------~------~ 100 80 60 40 20 0 

RIVER MILES ABOVE MOUTH 

FIGURE 11.-Dissolved-oxygen profiles for selected conditions of flow and ammonia 

loading. BOD loading held constant at levels observed during July-August 1973. 

Curves A, C, and Dare predicted; Curve B is observed. 

ing preliminary calibration of the WIRQAS 

model, predicted DO concentrations between 

RM's 13 and 5 were higher than those measured 

in the river, whereas predicted BODuu concentrations were considerably lower. Refined modeling 

tests suggested an undetermined oxygen demand 

of about 27,000 lb/d (12,000 kg/d) in this subreach. 

Field investigations (Chapter I) suggest that 

the demand is both suspended and bent hal in origin, but the exact causes are unknown. Possible 

factors that may either cause or affect the oxygen 

demand include: 

1. Unknown sources of raw sewage. 

2. Combined-sewer overflows. 

3. Urban storm runoff. 

4. Bilge water and refuse from ships. 

5. A net oxygen loss caused by algal respiration 

exceeding algal production owing to limited 

light penetration of the water column. 

6. A turbid, high-oxygen demanding, estuarinelike ~~null zone" resulting from tidally influenced hydraulic conditions. 

7. Sedimentation and decomposition of natural 

organics such as leaves and algae. 

These possibilities are presently the focus of 

further study in the hope that all or at least part 

of the demand can be related to controllable 

sources. If so, management control of such sources 

would provide a means for improving summertime DO by up to 8 percent of saturation at RM 5. 

SUMMARY AND CONCLUSIONS 

Future achievement of DO standards in the 

Willamette River will require continued low-flow 

augmentation in addition to pollution control. 

Minimum flows of 6,000 ft3/s (170 m3/s) (Salem 

gage) are presently (1976) needed to meet the 

State standards at existing BOD and ammonia 

loadings and with occurrence of the unidentified 

oxygen demand in Portland Harbor. As basin development continues, it is likely that summerM24 
time flows above 6,000 ft3

/s (170 m3/s) will be 

needed even with increased treatment removal of 

oxygen-depleting materials. 

Point-source loading of ammonia is the major 

cause of oxygen depletion below RM 86. Because 

most of the ammonia comes from one source, reduction of ammonia loading offers a relatively 

simple alternative for achieving a large improvement in summertime DO. 

Removal or partial reduction of the oxygen demand in Portland Harbor would improve the 

summer DO concentrations between RM's 10 and 

5. However, the feasibility of reducing the demand is yet to be determined. 

BOD loading from municipal waste-water 

treatment plants presently exerts a relatively 

small impact on DO. Increased efficiency of BOD 

removal at the largest municipal plants and at 

selected industrial plants might be desirable in 

the future. The benefits to be gained from this 

alternative would best be determined after ammonia loadings have been reduced to reasonable 

levels and the possibility of controlling the undetermined demand in Portland Harbor has been 

fully assessed. 

POTENTIAL FOR ALGAL PROBLEMS 

BACKGROUND 

In 1972, the Willamette River achieved the 

status of being the largest river in the United 

States on which all known waste-water sources 

(municipal and industrial) receive secondary 

treatment. Although this action sharply decreased the waste loading of carbon to the river, 

the loading of nitrogen and phosphorus remained 

high because these nutrients are inefficiently removed by secondary treatment processes. As a result, summertime concentrations of carbon in the 

Willamette are fairly low, but the concentrations 

of nitrogen and phosphorus are high. 

Despite the high nitrogen and phosphorus concentrations, 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 River could possibly be approaching a 

condition in which large, problem-causing 

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 and others, 1972). 

Concern about the potential for algal problems 

in the Willamette led to a search for a suitable 

assessment method. An applied eutrophication 

model would have been ideal. At present, however, the complex eutrophication process is so 

poorly understood that it is virtually impossible 

to develop applied models capable of quantitative 

predictions (McGauhey, 1974). 

Instead of attempting to formulate a predictive 

mathematical model, a qualitative descriptive 

study was designed to provide insight into the 

potential for nuisance algal growth. As applied in 

the algal study, descriptive assessment embodied 

problem definition, devising of hypotheses, collection and analysis of data, and exclusion of disproven hypotheses. For some specific 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 river-quality phenomena. 

The working hypotheses for this algal study 

were: 

1. Nuisance algal growths are prevented by low 

water temperatures. 

2. Nuisance algal growths are prevented by high 

summertime turbidities. 

3. Algal growth is limited by a scarcity of certain 

trace elements. 

4. Nuisance algal growths will develop provided 

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

loading ratios remain in the present proportion. This, in turn, is based on the hypothesis that certain undesirable species of 

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. 

5. Nuisance algal growths are prevented by short 

detention times of water in the Willamette. 

Using these hypotheses, available data on hydrology (fig. 3 and table 1) were analyzed to determine which reaches of the river have the 

M25 
greatest potential for 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. 

Reconnaissance and intensive type studies 

were conducted to define environmental conditions and the nature of algal populations in the 

lower two reaches of the Willamette (see Chapters C and G). Existing data were used to provide 

an historical comparison. 

ALGAL NUTRIENTS 

NITROGEN AND PHOSPHORUS LOADINGS 

During the low-flow period of 1974, point 

sources contributed about 80 percent of the orthophosphorus and 70 percent of the inorganic 

nitrogen (ammonia, nitrite, and nitrate) which 

entered the Willamette River (table 4). 

For orthophosphorus, municipal effluents contributed 66 percent and industrial effluents 14 

percent of the point-source loading (Chapter G). 

In contrast, industrial discharges accounted for 

55 percent and sewage treatment plants for 14 

percent of the point-source nitrogen. An undefined but localized source contributed 24 percent of the nitrogen between RM's 120 and 114 

(vicinity of Albany, Oreg.). This source was in addition to the estimated input from Fourth Lake 

and was also evident in data collected between 

1972 and 1975 by the Oregon DEQ. The resultant 

nitrogen loading has been categorized as unknown (table 4) because sufficient data were not 

collected to verify the source and the points of 

entry into the river. However, available information suggested that this nitrogen did not derive 

TABLE 4.-Estimated, dry-weather 1974 nutrient loadings, 

Willamette River, Oreg.l 

Orthophosphate as Ammonia + nitrite + phosphorus nitrate as nitrogen 

Source lb/d Percent lb/d Percent 

Land runoff __________________ 860 20 3,250 7 

Municipal effluents ---------- 2,850 66 6,950 14 Industrial effluents ____________ 580 14 27,530 55 Unknown2 ____________________ 12,000 24 

Total ------------------ 4,290 100 49,730 100 

1Data from Chapter G. 2See text for explanation. 

from normal land runoff and hence was a potentially controllable source. 

HControllable" sources thus contributed about 

90 percent of the inorganic nitrogen and 80 percent of the orthophosphorus which entered the 

Willamette during the peak period of algal productivity. Moreover, a comparison between 

mathematically flow-routed inputs and measured 

river loads indicated that bottom sediments did 

not contribute to the summertime inriver loads of 

dissolved nitrogen and phosphorus. 

The high percentage of phosphorus from pointsource discharges compares closely with the reported values of 87 percent for the Potomac River 

basin and 73 percent for the Hudson River basin 

(Jaworski and Hetling, 1970). However, the estimated 90 percent point-source loading of nitrogen 

exceeds by a wide margin the comparative values 

of 63 percent for the Potomac and 51 percent for 

the Hudson. This difference results primarily 

from a relatively large industrial loading of ammonia in the Willamette River basin, together 

with the large unknown (but probably industrially related) source of nitrogen in the vicinity of 

Albany. 

OBSERVED CONCENTRATIONS 

OF NITROGEN, PHOSPHORUS, AND SILICA 

During the 1973 and 1974 field seasons, the 

lowest determined concentration of orthophosphate-phosphorus was 0.035 mg/1 and the highest 

was 0.092 mg/1. Most concentrations fell between 

0.05 and 0.08 mg/1 (fig. 12), a narrow range that 

is consistent with the limited range of streamflows under which most of the samples were collected (see Chapter G). Moreover, not only were 

the concentrations relatively stable, but they 

were at all times well above the concentrations of 

phosphorus observed in some highly productive 

natural waters (Schindler, 1971). 

The concentrations of ammonia plus nitrate 

nitrogen (range of 0.28-2.90 mg/1) were considerably more variable than the phosphorus concentrations (fig. 12), but were always quite high relative to theoretical algal requirements. The scales 

in figure 12 are adjusted so that nitrogen (N) and 

phosphorus (P) concentrations appear equal when 

the two are present in a molar ratio of 16N:1P 

(approximate ratio in algal cells) (Stumm and 

Morgan, 1970). 

The concentrations of dissolved reactive silica 

ranged from about 4 to 10 mg/1 and, thus, were at 

M26 
2.0 .3 

1.0 

....... _ 

-..._ .2 --.............. -'""'() 

.1 

0 0 

2.0 .3 

w 

a: w 

a: 

1-

:::i 1.0 

a: 

w 

...__ 1- ....... _ ....... _ .2 :::i 

-....... a: -"""0 w 

0.. 

.1 (/) 

0.. ~ 

(/) 

~ 

<{ 0 

<{ 

a: 0 Q a: ..J (.!) 2.0 .3 ..J 

..J 

..J ~ 

~ ~ 

2 .2 z' 

2. 1.0 0 

i= 

0 

1-

<{ 

a: 

1-

2 

w 0 

u 

2 2.0 

.1 <{ 

a: 

1-

2 

w 

0 u 

2 

0 

.3 u 

0 (/) 

u ::::::l 

2 

w 

(.!) 

0 

a: 1.0 

t: 

2 

,, a: 

.2 0 .................. :I: 

0.. ' .......... (/) 

"o 0 

:I: .1 0.. 

0 0 

2.0 .3 

........ ......... 

.................. .2 

.................. 

''o 

.1 

-----~ 

0 

NOV 

FIGURE 12.-Time and spatial variations of selected major nutrient concentrations in the 

Willamette River, June-November 1974; 0, ammonia plus nitrate as nitrogen; .6.,orthophostPhate as phosphorus. 

all times above those required for diatom growth 

(Kilham, 1971). The data showed no evidence of a 

decrease in silica concentration from upstream to 

downstream locations. Additional samples collected between RM's 183 and 50 showed similar 

results. Thus, there was no apparent downstream 

depletion of dissolved silica in spite of the presence of suspended diatoms throughout the river 

M27 
and extensive beds of periphytic diatoms above 

RM52. 

ALGAL POPULATIONS 

Diatoms dominated the suspended-algae populations at all sites during both 1973 and 1974. 

(See Chapter G for details.) The most common 

diatom genera were Melosira, Stephanodiscus, 

Cymbella, Achnanthes, Nitzschia, and Fragilaria. 

Some blue-green algae and a variety of colonial 

green algae appeared but were less abundant 

than the diatoms. 

Densities of diatoms were rather high, with individual species present in abundances of 102 to 

103 cells/mi. During both years, the diatom populations were remarkably stable. The same species 

persisted, and there were no major changes in the 

total abundance of cells with location (sampling 

station). 

The common species of diatoms observed in the 

Willamette River can be characterized as cosmopolitan and eutrophic. No species appeared 

that would indicate highly polluted conditions, 

although some of the common diatoms are moderately tolerant of organic enrichment (Palmer, 

1969). Although short filaments of Anabaena 

were observed in some samples, no ttblooms" of 

blue-green algae or other algal types occurred during the study. Collectively, the composition of all 

suspended algae suggest that the lower two 

fz 

w 

(.) 

a: 

w 

a.. 

~ 50 f-~ 

z 

::::l 

0 

(.) 

:::2: 

en 

z 

<( 

(!) 

a: 

0 

0 

reaches of the Willamette were nutrient enriched, 

but not grossly polluted. 

The aggregate nature of diatoms in the lower 

Willamette indicates that the population resulted 

from both inriver growth of suspended forms 

(planktonic) and the exportation of cells from 

above RM 52, where most of the algae grow attached to river bottom rocks (periphytic). 

Figures 13 and 14 compare the relative abundances during 1963 (U.S. Public Health Service, 

1964) and 1974 of diatoms, green algae, and 

blue-green algae in the lower Willamette River. 

Differences in methodology between the two 

studies could well account for the observed higher 

abundance of green algae during 1963 (Williams, 

1964, 1972). However, the point of major importance is that the suspended algal population in 

the lower river was dominated by diatoms in 

1963, just as it was during 1973 and 1974. This 

observation is significant, because the lower Willamette was polluted with sewage and pulp-mill 

wastes in 1963 (Velz, 1961; Gleeson, 1972) but 

now: is relatively free of such organic pollution 

(Rickert and others, 1975b; Chapter I). Unfortunately, no 1963 data are available on nitrogen 

and phosphorus concentrations to provide a comparison of nutrient availability. 

Figure 15 shows the relative abundance of 

diatoms and blue-green algae in net plankton 

FIGURE 13.-Time variation of algal types in the Willamette River, at mile 8.1, April-September 1963 (U.S. Public 

Health Service, 1964). 

M28 
.... 

z 

w 

u 

a: 

w 

0.. 

z 

t-' 

z 

::> 

0 

u 

~ 

~ 

z 

<( 

(!) 

a: 

0 

100~~~~~~~~~~~~~~~F:7~~ 

o;bMb~~~~~~~~~mm~~ JUNE I JULY I AUG I SEPT 

FIGuRE 14.-Time variation of algal types in the Willamette River, at mile 7.0, JuneSeptember 1974. 

from the Tualatin River (see fig. 2). The illustrated data (Carter, 1975) indicate that the eutrophic but not heavily polluted reach at Farmington was dominated by blue-green algae 

during July-August 1973. During this period, 

streamflow in the Tualatin was low, at about 10 

ft3/s (0.3 m~/s). The Tualatin enters the Willamette at RM 28.6, and this tributary inflow may 

account for the low counts of Anabaena sometimes observed in the Tidal Reach. 

.... 

z 

w 

u 

a: 

w 

0.. 

z 

t-' 

z 

::> 

0 

u 

~ 

en 

z 

<( 

(!) 

a: 

0 

100 

/::::::::o:c 

··••••••••••••••••r=·-•........ : . 

50 

. :. :. :. :. :. :. :. :. ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~: ~::: =~ 

::)}~()}}}~/~}}~Ji~~i~~U~~~~~~}}@}}}~/H~~H~~H~~~~H~~H~~/~~~@@}//?/~~~\\ ··················. ····················· ..................................... ?~ })~ ..... . 

I••~~~~·::~::::~::::::::J::m~~m~~=u:::~=·l:!!::!1!1~!1!1 .\,!i~li!i!~lll!~llll~l!lll~!lii~l11~111•~•1•:~•••:~::.:t:.:,:~·-.:~·-\~:_.,:~;:•:~:•1~-\,~·:=.:~:•:·~:·;~·--:·~••::~,:_•,•_: ,:_il!tl!l!l~!lll~!l!l~!:i:i~.,..···•~=!!l..,.~:ii!~,i,•, .. ,.-~,:=\l~l~~~-2~·:;~!-::!i!~···!!•~,!,~.!!~==: lli =···=··· :::::::::::::: 

o l Jl I 

FIGuRE 15.-Relative abundance of diatoms and blue-green algae in net plankton of the Tualatin River at Farmington, 

Oreg., March-August 1973 (Carter, 1975). 

M29 
PRIMARY PRODUCTIVITY 

Figure 16 shows two examples of the vertical 

distribution of gross productivity at RM 7 .0. From 

such plots, total gross productivity was calculated 

for several sampling dates. The results ranged in 

magnitude from 1.6 to 4.4 (g02/m2)/d (grams DO 

per square metre per day) and, in comparison to 

data from other rivers, (see Chapter G, table 3) 

indicate that primary productivity in the lower 

Willamette was low to moderate. The data verify, 

however, that the suspended algae in the lower 

Willamette were metabolically active rather than 

dead cells transported from the periphytic beds 

above RM 52. 

The vertical distributions in figure 16 show 

that gross productivity decreased rapidly with 

depth, a result consistent with the turbid nature 

of the water. (See ~~Light Limitation.") 

EXAMINATION OF THE 

WORKING HYPOTHESES 

The following discussions examine the five previously listed working hypotheses to determine 

which best explain observed algal conditions in 

the lower Willamette River. 

LOW-TEMPERATURE LIMITATION 

Water temperatures in the Willamette River 

and in all tributaries reach a maximum during 

the July-August low-flow period. For the lower 

Willamette River, records compiled by the Willamette Basin Task Force (Appendix B, 1969) indicate the average water temperature during 

July ranges from about 20°C at RM 50 to about 

22°C at RM 7.0. 

During 1974, water temperature at RM 7.0 was 

about l0°C in mid-May and increased to only 

l3°C by mid-June. From this date, the temperature increased rather steadily to a maxim urn of 

about 24°C in early August. The temperature 

stayed about 20°C through the remainder of August and early September and then decreased 

steadily through the remainder of September. 

The recorded temperatures in the lower Willamette River are lower than those observed in 

many lakes and rivers that experience nuisance 

algal growths. Cairns (1956) noted that diatoms 

generally are favored at temperatures below 

25°C, green algae between 30 to 35°C, and bluegreen algae above 35°C. Hutchinson (1967) concluded that blue-green algae may dominate in 

mid-to-late-summer because they out-compete 

other forms by growing faster at low inorganic 

nutrient levels and at high temperatures. However, in the Willamette River basin, blooms of 

Anabaena (a nuisance blue-green alga) occur 

under the quiescent conditions in certain headwater reservoirs at water temperatures below 

l8°C. 

In spite of this occurrence, the moderate summer temperatures in the lower reaches of the Willamette could be one factor that helps maintain 

suspended algal growth in its present desirable 

state. 

LIGHT LIMITATION 

The water in the lower Willamette River was 

relatively turbid during the study periods in 1973 

and 197 4. Extinction coefficients, calculated from 

the measurement of relative light at the 10-ft 

(3-rn) depth, were between 1.4 m-1 and 2.0 m-1

. 

Coefficients caluclated for the 3-ft (1-rn) depth 

RIVER MILE 7.0 

0 0 0 0 

9/17/74 9/19/74 

1- Cl) 

w w w I:I: u.. 5 5 1-

~ w 2 2 :E 'I~ 

1- Gross productivity Gross productivity ~ CL 4.4(g0 2tm2)/d 2.0(g02/m2)/d 'I~ 

w 

Cl 1-

10 10 CL 

w 

Cl 

4 4 

0 2 3 0 2 3 

DISSOLVED OXYGEN, PRODUCED IN LIGHT-DARK BOTTLES TESTS, IN MILLIGRAMS PER LITRE PER DAY 

FIGURE 16.-Vertical distribution of primary gross productivities in the Willamette River, at mile 7.0, for selected 

times during summer 1974. Gross productivities for the euphotic zones (reported as (g02 /m2 )/d) were calculated 

according to Slack, Averitt, Greeson, and Lipscomb, 1973. 

M30 
were somewhat higher owing to selective 

wavelength absorption. 

The euphotic zone of a water body is the thickness of the surface layer that receives sufficient 

light to permit algal photosynthesis to equal or 

exceed algal respiration. This thickness is approximately equal to the depth to which 1 percent 

of the surface light penetrates. The determined 

range of extinction coefficients implies a 

euphotic-zone thickness between 7.5 to 11.5 ft (2.3 

to 3.5 m) along the course of the Willamette 

River. In contrast, the representative midchannel 

water depth is 40ft (12m) in the Tidal Reach and 

25 ft (8 m) in the Newberg Pool (table 1). Generally, in these reaches, both the water and suspended matter is completely mixed to the bottom 

(unstratified); consequently, only part of the suspended algae is capable of photosynthesis at any 

moment, whereas algae and all other organisms 

are respiring throughout the entire water column. 

The above information, when combined with 

the production data (see ((Primary Productivity") 

and other evidence (See Chapter G for elaboration), indicates that low light availability restricts the rate of primary productivity in the 

Tidal Reach and the Newberg Pool. It seems that 

there is insufficient light throughout the water 

column for suspended algae to grow rapidly in 

these reaches. 

From a management standpoint, there are two 

important questions concerning light limitation: 

(1) what are the natures and sources of the materials causing the high light extinction and (2) if 

turbidity were decreased, would the increased 

light availabilities result in greater primary 

productivities and possibly cause undesirable 

shifts in algal populations? Unfortunately, at 

present, there is insufficient information to answer either question. Until such time that definite 

answers are available, it may be prudent to assume that measures aimed at decreasing summertime turbidities (if this is indeed possible) 

might cause undesirable changes in algal-growth 

dynamics. 

TRACE-NUTRIENT LIMITATION 

Bioassay tests were conducted to determine if 

addition of selected nutrients would stimulate 

the growth of Willamette River algae under controlled conditions. The tests were conducted on 

three occasions, and one set of results is shown in 

figure 17. In no case did the productivity of 

treated samples exceed that in controls by a significant amount. The overall results indicate that 

nutrient availabilities in the lower Willamette 

River were not limiting to algal productivity nor 

to possible development of nuisance algal conditions. These results are consistent with the many 

possible sources of trace elements and with the 

presence of numerous metals in the river-bottom 

sediments. (See uTrace-Metal Occurrence.") 

MAJOR-NUTRIENT LIMITATION 

CARBON 

The Willamette is a low alkalinity (15-25 mg/1 

as CaCOa) river (U.S. Geological Survey, 1974), 

so the possibility of a carbon limitation on algal 

production needs to be considered. In assessing 

this topic, there are two relevant questions: (1) 

Are carbon concentrations possibly limiting to 

gross production of phytoplankton and (2) how 

does the distribution of carbon among the inorganic forms affect the qualitative nature of the 

phytoplankton? 

The first question can be assessed by comparing 

the ratios of total carbonate carbon to inorganic 

nitrogen to orthophosphorus in Willamette River 

water to reported ratios of carbon:nitrogen:phosphorus (C:N:P) in algal protoplasm. During July 

and August 1974, the C:N:P ratios at RM 7.0 in 

the Willamette varied from 185:21:1 to 285:60:1. 

In contrast, the commonly quoted ratio of these 

elements in algae is 106:16:1 (Stumm and Morgan, 1970), and a ratio reported as typical for 

blue-green algae is 40:7:1 (James and Lee, 1974). 

Comparison of the two sets of ratios shows that, 

on a relative basis, carbon in the Willamette was 

more abundant than the phosphorus needed for 

algal growth and equal to or more abundant than 

the required nitrogen. These findings suggest 

that carbon was not limiting to algal production 

in the lower Willamette River. 

The second question can be assessed by examining diel records of pH values. During July and 

August of 1973 and 1974, continuous 3-day pH 

traces were obtained at RM's 7.0 (depths of 3 

and 20ft, or 1 and 6 m) and 12.8 (depths of 3ft, 

or 1 m). During each of six measurement periods 

the maximum daily variation in pH was from 6.8 

to 7.1. 

The stability of pH near neutrality indicates 

that free carbon dioxide ( C02 ) was not depleted by 

M31 
0 

w 

0 

0 

<{ 

(I) 

..... 

z 

w 

a: 

..... 

:::> 

z 

0 

I 

Phosphorus 

0.2 mg/1 P04-P 

I 

Ammonia 

3.3 mg/1 NH4-N 

I 

Nitrate 

3.3 mg/1 N03-N 

I 

Phosphorus+ Ammonia+ Nitrate 

0.2 mg/1 P04-P, 3.3 mg/1 NH4-N, 3.3 mg/1 N03-N 

I 

Micro-nutrients 

B,Mn,Zn,Co,Cu,Mo,Fe 

I 

Control 

I 

I 

I 

I 

I 

I 

I 

I 

2 3 

DISSOLVED OXYGEN PRODUCED, IN MILLIGRAMS PER LITRE PER DAY 

FIGURE 17.-Effect of nutrient additions on algal productivity ofWillamette River samples, mile 7.0, July 24, 1973. 

algal production to the point where extensive 

bicarbonate carbon was utilized. Such a condition 

is favorable to maintenance of diatom and 

green-algae populations. In contrast, blue-green 

algae tend to dominate under conditions of high 

pH, because their advantageous uptake kinetics 

allow them to compete better for bicarbonate C02 

once free C02 is depleted (King, 1970; Shapiro, 

1973). In the lower Willamette River, there apparently was a maintenance of sufficient free co~ 

to prevent conditions where blue-green algae 

would have competitive advantage over diatoms 

and green algae. 

NITROGEN AND PHOSPHORUS 

The concentrations of nitrogen and phosphorus 

in the lower Willamette River are higher than 

those reported as sufficient to cause nuisance 

algal blooms in lakes (Sawyer, 1954; Schindler, 

1971), but lower than concentrations observed in 

certain rivers and estuaries that have nuisance 

algal problems (Shane and others, 1971; Jaworski 

and others, 1972; Clark and others, 1973). 

The observed nitrogen and phosphorus concentrations seem sufficient to support higher levels of 

primary production than those measured in the 

river. This deduction is supported by the nutrient 

enrichment tests (see fig. 17) which indicated that 

neither nitrogen nor phosphorus was limiting to 

algal productivity at RM's 7.0 and 12.8. 

Comparison of N:P ratios in Willamette River 

water (fig. 12) to the commonly reported ratio for 

algal tissue (16:1) indicates that nitrogen was 

relatively more abundant than phosphorus by a 

wide margin during 197 4. Thus, if algal production were greatly increased and nutrient loading 

remained constant, phosphorus (not nitrogen or 

carbon) would probably become the limiting 

major nutrient. However, the 1973 and 1974 concentrations of phosphorus were far from being deM32 
pleted to the point where limitation of productivity was even a remote possibility. 

DETENTION-TIME LIMITATION 

OBSERVED AND REPORTED RELATIONSHIPS 

As in the Willamette, the suspended-algae 

populations of most rivers in the United States 

(Williams, 1964; 1972) and throughout the world 

(Hynes, 1970) are dominated by diatoms. Exceptions to the general pattern of diatom dominance 

do occur, however, and are usually observed in 

parts of river systems having long detention 

times (slow rates of water exchange). As described in Chapter G, detention time has been 

noted by several authors as the dominant factor 

in algal productivity and succession in certain 

rivers, estuaries, lakes and reservoirs. 

As previously noted (see ~(Reservoirs and Historical Streamflow Patterns"), summer low flows 

in the Willamette River are augmented by reservoir releases to maintain a minimum of6,000 ft3/s 

(170 m3 /s) at Salem. At this discharge, waterdetention times are small, with volumetric displacement times of3.9 days for the Newberg Pool 

and 7.5 days for the Tidal Reach down to RM 5.0 

(point of mixing with the Columbia River). The 

water at this discharge is confined within welldefined banks (very few sloughs and side channels) and is totally mixed to depth. Thus, in the 

lower Willamette, the total detention time of 

water during the period having the slowest flow 

velocities and the highest water temperatures is 

about 11 days. 

In contrast to the Willamette, low-flow detention time in the 35-mi (56-km) Upper Potomac 

Estuary, where algal problems occur, is reported 

as 50 days (Wa]ker, 1971). Thus, under low-flow 

conditions, detention ·time in the freshwater 

reach of the Potomac Estuary is four to five times 

greater than that observed in the Willamette 

River between RM's 52 and 5. 

Based on the results and on comparisons with 

other rivers, we believe that short detention time 

is the primary reason productivity is low in the 

Willamette and diatoms dominate in spite of the 

high availability of nitrogen and phosphorus. 

However, based on published results (Fogg, 

1965), the 11-day, low-flow detention time seems 

long enough to permit the reproduction of 

planktonic blue-green algae. Thus, the absence of 

nuisance blooms in the Willamette apparently resuits from the influence of detention time on other 

factors which control algal growth. The following 

section examines several relationships which 

could be prominent in the Willamette and in 

many other rivers. 

ROLE OF DETENTION TIME AND LIGHT PENETRATION 

IN CONTROLLING BIOMASS AND 

THE NATURE OF ALGAE 

Figure 18 schematically portrays the relationship of algal biomass and dominant algal types to 

water-detention time and light penetration. The 

schematic is based on observations made in waters of the Willamette system but is presented as 

a conceptual model to be considered for all river 

basins. 

The schematic was devised to generalize the locations and stream-current conditions under 

which nuisance algal growths are likely to occur. 

Nuisance algal conditions include problems of 

esthetics, DO depletion, and increased watertreatment costs. In this context, the occurrence of 

nuisance conditions depends on the type and 

amount of biomass (weight of algal cells per unit 

volume of water) that can develop and accumulate in the water. 

In the diagram, water-detention time increases 

toward the right and biomass toward the top. The 

figure body is divided into three hydraulicecological habitats. The habitat at the left is representative of fast-moving shallow rivers in 

which the photosynthetic zone extends to the bottom. Under such conditions, periphytic diatoms 

are typically the dominant algal type and both 

primary production and biomass are high. 

The habitat at the center of the schematic is 

typical of moderate-velocity rivers in which average depth is high relative to the penetration of 

light. This habitat characteristically occurs 

downstream from the regime at the left of the 

figure and is commonly the condition found over 

long reaches of most large rivers. In such waters, 

the dominant algae are planktonic diatoms. 

Biomass is relatively low because of lower productivity and the dispersion and transport of cells 

by the current. This hydraulic-ecological habitat 

can also occur in tidal rivers (such as the Willamette Tidal Reach) where net downstream velocities are low but the waters are well mixed 

owing to tidally induced currents. 

The hydraulic-ecological habitat at the right of 

figure 18 is representative of sluggish and standM33 
HYDRAULIC-ECOLOGICAL HABITATS 

HIGH-VELOCITY RIVERS MODERATE-VELOCITY RIVERS SLUGGISH AND STANDING WATERS 

A. Shallow A. Deep A. Deep 

w 

z 

0 

N Periphytic diatoms Planktonic diatoms Planktonic diatoms, 

greens, and blue greens (..) 

i= 

0 

J: 

0.. 

::::> 

w 

LL 

0 

w 

:2 

::::> 

_. 

0 

> 

!::: 

z 

::::> 

a: 

w 

0.. 

(/). 

(/) 

<( 

:2 

0 

ii5 

_. 

<( 

(!) 

_. 

<( 

B. Shallow 

Planktonic diatoms, 

greens, and blue greens; 

Periphytic diatoms and 

FIGURE lB.-Conceptual diagram relating algal biomass and dominant algal types to water detention time and light 

penetration. Shallow implies that the euphotic zone extends to the bottom; deep implies the euphotic zone does not 

reach the bottom. 

ing waters such as pooled rivers, lakes, reservoirs, and poorly mixed estuaries. In such waters, 

environmental conditions can be diverse and, depending on depth, the dominant algal types may 

range from planktonic diatoms, greens, and 

blue-greens to periphytic diatoms and filamentous greens. In the euphotic zone of this habitat, 

productivity tends to be high, and biomass accumulation can be great. This combination often 

leads to the development of nuisance algal conditions. The deep waters of this hydraulic regime 

are commonly poorly mixed or stratified. It is at 

the surface of these waters that planktonic bluegreen blooms must commonly occur, sometimes 

as the result of a seasonal succession beginning 

with diatoms and green algae. 

With figure 18 for perspective, we can 

hypothesize why significant growth of blue-green 

algae does not occur in the Willamette nor in 

most large free-flowing rivers (as represented by 

the middle regime). 

The exact relationship between water-detention time, biomass, and the qualitative nature 

of algae depends on a large number of factors. 

Included among these are nutrient availability, water temperature, light penetration, and 

perhaps simply the requirement of some algae for 

a period of adjustment to new environmental conditions. However, the crux of the conceptual 

model (fig. 18) is that in free-flowing rivers detention time largely controls these factors in a manner that prevents the onset of conditions conducive to the growth of planktonic blue-green algae. 

Perhaps most importantly, flowing water provides a constant chemical influx that prevents 

depletion of major nutrients to concentrations at 

which blue-green algae would enjoy a competitive 

advantage. In addition, most flowing waters remain unstratified (except estuaries), and temperatures do not reach the same levels that would 

occur in stratified standing water under identical 

climatic conditions. Moreover, because flowing 

water carries suspended sediment, rivers are 

usually more turbid and permit less light peneM34 
tration than standing water. Also, in flowing water, turbulent mixing negates the buoyancy advantage that blue-green algae enjoy in standing 

water because of their unique possession of gas 

vacuoles (Walsby, 1970). 

All these factors may be important in various 

combinations and degrees in different rivers. In 

the Willamette River, the most important factor 

is probably the maintenance of a balance in nutrient concentrations by flow and mixing, but low 

light availability resulting from turbidity also 

plays a role. 

SUMMARY AND CONCLUSIONS 

The key to keeping algal growth in the Willamette River at its present balance appears to be 

control of those factors that maximize summertime flow and thus minimize time-of-passage. 

Such control would require maintenance of present levels of flow augmentation and avoidance of 

large increases in summertime diversions. The 

high observed concentrations of nitrogen and 

phosphorus result primarily from point-source 

loading but, under the present physical conditions, do not stimulate algal succession leading to 

nuisance growths. It appears that treatment to 

remove nitrogen and phosphorus from point 

sources is not needed to control algal growth provided summer low flows are maintained in the 

range of 6,000 to 7,000 ft3/s (170 to 198 m3/s). 

However, algal problems might develop if flow 

were greatly reduced and the point-source nitrogen and phosphorus loadings remained at the 

1974 levels. 

The results of this study indicate that arbitrary 

standards for permissible nitrogen and phosphorus concentrations in rivers may bear little 

relationship to primary productivity and to 

algal-growth dynamics. This means that the need 

for advanced waste-treatment removal of phosphorus and nitrogen must be assessed on a riverby-river or reach-by-reach basis. The environmental benefits that will result from different 

pollution-control measures can only be determined by conducting sound river-quality assessments that are keyed to local conditions. 

TRACE-METAL OCCURRENCE 

BACKGROUND 

Many materials discharged into river systems 

can be toxic to aquatic organisms if 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 ubiological magnification." 

Review of industrial-discharge permits for the 

Willamette River basin indicates that there is 

very little possibility of toxic industrial organics 

entering the Willamette River. Furthermore, 

over the last 10 years, hard pesticides (such as 

DDT) have not been used in the basin for 

disease-vector control nor for widespread plantpest control. In contrast, there are several industrial sources of trace metals in addition to the 

metals that enter the river in urban runoff. Thus, 

if a toxicity problem occurred, it would probably 

result from the accumulation of trace metals. 

Prior to this study, few data existed for the Willamette River system on the content of 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 reconnaissance study was designed to 

determine the concentration and distribution of 

trace metals in river-bottom sediments. The objectives of this reconnaissance were to provide not 

only baseline information for future comparison, 

but also an alert on possible accumulation of metals. 

POSSIBLE SOURCES OF TRACE METALS 

Besides natural geological background, the 

possible sources of trace metals in the W illamette 

River basin include industrial activities, urban 

runoff, municipal waste-water discharges, and 

old mining areas. Table 5 was compiled from unpublished records of the Oregon DEQ to show the 

river-mile location on the Willamette of most 

known or potential sources of metals. The table 

also indicates the discharge locations of 

tributaries. 

In the Portland metropolitan area, the land 

corridor along the Willamette is used for many 

industrial and shipping activities which represent potential sources of metals (table 5). In addition, the city of Portland is served by a combined 

sewerage system that during intense rainfall 

M35 
TABLE 5.-Possible sources of trace metals in the Willamette River system1 

Location2 

Industries and industrial waste-water effluents Municipal, secondary waste-water effiuents3 

Tributaries and urban runoff 

0-6.0 ----------------------------------------------------------------------------- Intrusion of Columbia River sedColumbia Calcium carbide and related iments. 

Slough (1.2). products. 2.5-12.0 __________ Shipping terminals. 

3.0-8.0 __________ Oil tank farms. 

3.3- ___________________________________________________________________________ --- Multnomah Channel. 

7.0____________ Agricultural organic chemicals 

(Cr, Cu, Ph, Ni, Zn). 

7-17 ----------------------------------------------------------------------------- Combined sewer overflows from 

7.4____________ Chlorine and related products Portland (Ph and others). 

Swan Island 

Channel (8.1). 

(Cr, Zn). 1 Drydocks and ship repairs. 

11.0____________ Cement plant. 

13.7------------ Ship salvage yards. 

17.0-27.5 --------------------------------------------------------------------------- lJrban storm drainage from Port18.4------------------------------------------------ Milwaukie-1.9 Mgal/d land metropolitan area (Ph (Cr, Ni, and Zn from and others). 

20.1 _______________________________________________ _ 20.3 _______________________________________________ _ 24.1 _______________________________________________ _ 25.2 _______________________________________________ _ 

27.6____________ Ground-wood pulp and paper 

mill-13.5 Mgal/d (Zn). 

plating wastes). 

Oak Lodge-1.8 Mgal/d 

Tyron Creek-3.7 Mgal/d 

West Linn-0.7 Mgal/d 

Oregon City-2.8 Mgal/d 

27.8------------------------------------------------ West Linn-0.5 Mgal/d. 28.0____________ Ground-wood and magnesium 

sulfite pulp and paper mill12.9 Mgal/d (Zn). 

28.5------------------------------------------------------------------------------- Tualatin River. 33.0________________________________________________ Canby-0.3 Mgal/d 

35.6------------------------------------------------------------------------------- Molalla River. 

48-51 ----------------------------------------------------------------------------- lJrban storm drainage from 

49.2____________ Ground-wood and magnesium Newberg (Ph and others). 

sulfite pulp and paper mill11. 7 Mgal/d (Zn). 

50.3------------------------------------------------ Newberg-0.7 Mgal/d 

54.8------------------------------------------------------------------------------- YamhillRiver. 

80~~~7~0-============================================--~~!~~--~=-~-~~~~------------ lJrban storm drainage from 

Salem (Ph and others). 

84.2------------------------------------------------------------------------------- Boise Cascade Slough. 85.2____________ Ammonium sulfite pulp and paper mill. 

107.7------------------------------------------------------------------------------- LuckiamuteRiver. 

108.0------------------------------------------------------------------------------- SantiamRiver. 

Fourth Lake Metal extraction and processing, 

(117.0). Kraft pulp and paper mill, 

resin plant, wood flour mill, 

oil tank farm (Zr, Hf, Ta, Nb, 

V, W, Mo, and others). 117.9________________________________________________ Albany-5 Mgal/d 118-120 _____________________________________________________________________________ lJrban storm drainage from Albany (Ph and others). 

119.6------------------------------------------------------------------------------- CalapooyaRiver. 

130-134 _______ ---------------------------------------------------------------------- lJrban storm drainage from Corvallis (Ph and others). 

~~g:g================================================--~~-~~~~~~~!~~-~---------- MarysRiver. 132.2____________ Hardboard mill. 

147.5____________ Kraft pulp and paper mill. 148.0 _______________________________________________________________________________ LongTomRiver. 

174-187 _____________________________________________________________________________ lJrban storm drainage from 

Eugene-Springfield (Ph and 

others) 

174.9------------------------------------------------------------------------------- McKenzieRiver. 178.6________________________________________________ Eugene-13 Mgal/d 184.3____ ____ ________ ____________ _________________ ___ Springfield-5 Mgal/d 

187.0 _______________________________ ------------------------------------- _____ ______ Confluence of Coast Fork and 

1Specific metals associated with specific sources are identified in brackets by their chemical symbols. 2River-mile location or river-mile interval unless specifically named. 3Approximate flows for summers of 1973 and 1974. 

M36 

Middle Fork. 
overflows into the Willamette carrying metals 

from raw sewage, various industries, and street 

runoff. (Dry-weather flow is diverted via the 

municipal treatment plant to the Columbia 

River.) Moreover, between RM's 17 and 25.6, 

street runoff periodically enters the Willamette 

through a separate storm-drainage system, and 

farther upstream, storm drainage and municipal 

secondary effluents represent additional tracemetal sources in other urban areas. 

Pulp and paper production is a major industry 

of the Willamette River basin. For many years 

zinc hydrosulfite has been used as a brightening 

agent in the ground-wood pulping process at 

three large mills (table 5). The three plants and 

their 1973 zinc loadings to the Willamette were 

Publishers Paper Co. at Newberg (RM 49.2), 71 

tons (64 t) (Zenon Rozycki, oral commun., 1975); 

Publishers Paper at Oregon City (RM 28.0), 89 

tons (81 t); and Crown Zellerbach Corp. at West 

Linn (RM 27.6), 75 tons (68 t) (Herman Amberg, 

oral commun., 1975). In compliance with orders of 

the Oregon DEQ, Publishers switched to a nonzinc brightening agent at both plants in spring 

1975, and Crown Zellerbach will switch by July 

1977. 

There are seven mineralized areas (fig. 19) in 

the Willamette River basin (Oregon Department 

of Geology and Mineral Industries, 1951; Willamette Basin Task Force, Appendix A, 1969) 

which at one time or another were commercially 

mined. Mercury was once mined from the Black 

Butte area on the Coast Fork above Cottage 

Grove Reservoir, and from the Oak Grove Fork 

area in the headwaters of the Clackamas River. 

The five other areas were mined at various 

times for copper, gold, lead, silver, and zinc. The 

five areas and their drainage tributaries are (see 

fig. 19): 

1. North Santiam district; tributary to the Santiam River. 

2. Quartzville district; tributary to the Santiam 

River. 

3. Blue River district; tributary to the McKenzie 

River. 

4. Fall Creek district; tributary to the Middle 

Fork Willamette. 

5. Bohemia district; tributary to the Coast Fork 

Willamette. 

No natural deposits of cadmium or chromium 

are known to exist in the Willamette River basin. 

No commercially exploitable source of arsenic exists, but high concentrations of this metal occur in 

the ground water of Lane County at the southern 

end of the basin (Goldblatt and others, 1963). 

Fourth Lake, near Albany, is worthy of special 

mention. The Lake, which is actually a slough, 

receives drainage from 11 industries, including 

the metal-extraction and processing operations at 

Teledyne-Wah Chang. Wah Chang extracts zirconium and hafnium from imported ores and produces various alloys from these metals and from 

tantalum and niobium, which are purchased in 

purified form (Tom Nelson, Teledyne-Wah 

Chang, oral and written communs., 1975). The 

imported ores also contain scandium, yttrium, 

lanthanum, and ytterbium. Additional metals 

used in production of alloys include molybdenum, 

tungsten, tin, chromium, and nickel. At one time, 

Wah Chang also used silver in the production of a 

special tungsten alloy. 

From the information in table 5 and figure 19, 

it can be seen that the potential sources of trace 

metals to the Willamette River are generally 

known. To determine the effects of these sources, 

it was necessary to develop an approach for the 

collection and preparation of samples. 

SAMPLING APPROACHES AND RATIONALES 

For purposes of this study, bottom sediments were 

considered the most desirable sampling medium. 

Because trace metals associate strongly with particulate materials, bottom sediments can act as 

metal accumulators during periods of low 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 stable low-flow condition thus provide the opportunity to obtain information on the presence and distribution of 

metals over an extended period of time. Such information can be used to delineate areas of 

anomalously high concentrations and possible 

sources. 

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

below potential trace-metal sources (table 5). 

The objective of field sampling was to obtain 

sufficient fine-grained material from each site for 

the laboratory analyses. In the Tidal Reach, satisM37 
INDEX MAP OF OREGON 

I 

N 

I 

w 

rrJ) 

<( 

0 

u 

EXPLANATION 

l]:ili:ilit~ A::r~:Jo~~~:ve~~' 

• Areas once mined for 

mercury. 

43• Sediment sampling 

site. 

0 10 20 MILES 

t-1 ---r-f _....! -,..-_,....,, I 

0 10 30 KILOMETRES 

w 

0 

<( 

~ <( 

(.) 

FIGURE 19.-Willamette River basin, Oreg., showing sediment sampling sites in the Upstream Reach and 

historical mining areas. 

M38 
12:fod' 12~45 12~3o' 

~------------,---------------~-r-r~~,-------------------------~---, 45°45 

II INDEX MAP OF OREGON 

0 

I 

0 

I 

5 

5 

I 

I 

10 

I 

10 MILES 

I 

15 KILOMETRES 

CITY 

FIGURE 20.-Sediment sampling sites in the Tidal Reach and Newberg Pool. 

factory samples were obtained with a Petersen 

dredge by compositing two or more bites at the 

visual center of flow. The center of flow was used 

in preference to the center of the cross section 

because, in many subreaches, the channel and 

most of the flow is near one bank. At each location, the specific sampling site was determined by 

combining information provided by aerial photoM39 
graphs (U.S. Army Corps of Engineers, 1973) 

with information attained by visually estimating 

the discharge at various points in the cross section. 

In many upstream subreaches, the riverbed is 

almost completely covered with gravel. In these 

locations, the sampling approach consisted of 

searching with an Ekman dredge for small areas 

of fine-grained sediments. Thus, the samples are 

unrepresentative of the channel-bed materials. 

This sampling approach simply uses the fine 

materials in bottom sediments as a natural 

trace-metal concentrator to determine the relative occurrence of trace metals in each subreach. 

Bottom-sediment samples were collected from 

44 sites (figs. 19 and 20) in late September 1973 

after a period of more than 4 months of steady low 

flow. Thirty-one samples were taken from the 

Willamette River and 13 from tributaries, 

sloughs, and other adjacent waters. 

Geographically, 19 of the sites were associated 

with the 26.5 mi (42.6 km) Tidal Reach (see 

fig. 3 and table 1), 7 with the 25.5 mi (41.0 km) 

Newberg Pool, and 18 with the 135 mi (217 km) 

Upstream Reach. The sampling density was designed to be greatest in the Tidal Reach because 

this section of the river is the most highly urbanized and, as previously noted, the subreach 

between RM's 10 and 3 is the primary depositional area of the Willamette River system. 

LABORATORY PROCEDURES AND RATIONALES 

PHYSICAL PROCEDURES 

Laboratory procedures are described in considerable detail in Chapter F. However, a brief synopsis of the procedures is needed here to provide a 

basis for presenting and discussing the results. 

Prior to analysis of samples for metals, the 44 

samples were size fractionated. First, the samples 

were sieved through a 2-mm sieve to exclude 

gravel-sized materials. Then, part of the <2-mm 

materials of each sample was analyzed to determine the percentages of sand, silt, and clay. Finally, another part of each sample was size fractionated at 20 JLm to obtain subsamples of very 

fine sediments. 

One reason for obtaining <20-JJ-m fractions was 

to minimize variations in metal concentrations 

that normally arise from sample-to-sample differences in the proportion of fine-grained materials. Data presented in Chapter F show that this 

objective was attained and that the metal concentrations in the <20-JJ-m fractions thus provided a sensitive comparative basis for detecting 

trace-metal pollution. 

A second reason for fractionating the samples 

was that the <20-JJ-m materials are roughly comparable in grain size to claystones and shales, and 

also to the fine-grained fractions of soils. Fractionation at 20 JLm thus provided a basis for comparing the trace-metal results to existing 

geochemical data. 

ANALYSIS OF METALS 

Fifty elements were investigated using a sixstep semiquantitative emission-spectrographic 

method developed for geochemical exploration 

(Myers and others, 1961). Because the analyses 

were semiquantitative, the emission-spectrographic method was used primarily for the 

scanning of trace-metal occurrence. The intent of 

its use was to determine if any of the wide array 

of investigated metals was present in anomalously high concentrations. Only the <20-JJ-m fractions of samples were analyzed by this method. 

Atomic-absorption spectrophotometry was used 

to determine more quantitatively the concentrations of cadmium, chromium, copper, lead, mercury, silver, and zinc, and colorimetry was used 

for arsenic. These eight metals were specifically 

selected for intensive analysis because they are 

widespread byproducts of man's activities and are 

potentially toxic to aquatic organisms. The wetchemical methods used to determine the metals 

were developed for geochemical prospecting 

(Ward and others, 1963, and 1969). These 

methods are less sensitive than others presently 

available but are adequate for a reconnaissance. 

Both whole samples ( <2 mm) and the prepared 

<20-JJ-m fractions were analyzed for the eight 

metals. 

RESULTS 

Results obtained by the wet-chemical methods 

are presented in table 6 for both the <2-mm and 

<20-JJ-m materials. For easier inspection, the 

<20-JJ-m results are geographically summarized 

as averages and ranges in table 7. 

The emission spectrographic data agreed with 

the results reported in table 6. In addition, the 

data showed that the less common trace metals 

were present in anomalously high concentrations 

M40 
TABLE 6.~oncentrations of trace metals in bottom sediments from the Willamette River and adjacent waters 1 

('Concentrations• in parts per million] 

Sample 

number 

l_ ____ _ 

2 _____ _ 3 _____ _ 4 _____ _ 

5 _____ _ 

6 _____ _ 

7------ 8 _____ _ 

9 _____ _ 

10 _____ _ 

1L ____ _ 12 _____ _ 13 _____ _ 14_ ____ _ 

15 _____ _ 

16 _____ _ 

17------ 18 _____ _ 19 _____ _ 

20 _____ _ 2L ____ _ 22 _____ _ 23 _____ _ 

24 _____ _ 25 _____ _ 26 _____ _ 

27------ 28 _____ _ 

29 _____ _ 30 _____ _ 

3L ____ _ 32 _____ _ 33 _____ _ 34 _____ _ 

35 _____ _ 

36 _____ _ 

37------ 38 _____ _ 39 _____ _ 40 _____ _ 4l_ ____ _ 

42 _____ _ 43 _____ _ 44 _____ _ 

Site3 As 

Columbia River 10 Columbia Slough 10 1.5 10 

1.5 <10 

1.5 <10 1.5 20 Multnomah Channel 20 6.0 10 Swan Island 

Channel 20 8.5 10 8.5 10 8.5 10 8.5 10 11.7 10 13.7 10 

17.0 10 

21.1 10 Clackamas River 10 

25.6 10 

27.9 10 Tualatin River 10 

34.1 10 34.9 10 45.8 10 

48.6 10 50.2 <10 54.0 10 

69.0 10 Boise Cascade Slough 10 

86.7 10 Santiam River 10 

112.6 10 Head-Fourth Lake 40 Middle-Fourth 60 Lake 

Fourth Lake near confluence <10 117.0 10 120.0 10 130.1 10 Marys River 10 141.3 10 161.2 10 178.1 10 

185.3 10 Coast Fork 10 

Cd 

1 

1 

.5 

.5 

.5 

1 

1 

.5 

.5 

.5 

.5 

1 

.5 

.5 

1 

.5 

.5 

.5 

.5 

.5 

1 

.5 

.5 

.5 

.5 

1 

.5 

1 

1 

.5 

.5 

.5 

1 

1 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

Cr 

65 

80 

85 

90 

100 

90 

55 

55 

70 

80 

75 

65 

70 

55 

65 

70 

60 

90 

65 

70 

65 

75 

70 

65 

75 

65 

80 

70 

65 

60 

60 

80 

95 

75 

80 

75 

70 

85 

135 

75 

80 

65 

65 

75 

<2-mm materials4 

Cu 

5 

10 

10 

10 

15 

15 

5 

5 

25 

15 

15 

10 

15 

5 

10 

10 

10 

5 

5 

5 

5 

10 

5 

10 

10 

15 

15 

5 

10 

10 

5 

5 

30 

30 

15 

10 

5 

10 

10 

5 

5 

5 

5 

15 

Ph 

5 

5 

20 

20 

10 

10 

5 

10 

35 

10 

30 

20 

20 

5 

15 

20 

10 

5 

10 

5 

15 

10 

5 

10 

10 

20 

15 

5 

60 

5 

5 

5 

65 

100 

15 

5 

10 

5 

5 

5 

10 

5 

10 

35 

Hg 

0.15 

.17 

.10 

.27 

.09 

.08 

.08 

.14 

.11 

.11 

.08 

.13 

.20 

.10 

.10 

.19 

.16 

.07 

.08 

.08 

.17 

.26 

.15 

.13 

.16 

.12 

.25 

.14 

.14 

.08 

.14 

.08 

.12 

.80 

.16 

.20 

.08 

.12 

.18 

.08 

.26 

.04 

.11 

.08 

Ag 

<0.5 

< .5 

< .5 < .5 

< .5 

< .5 < .5 < .5 

< .5 < .5 < .5 

< .5 < .5 

< .5 < .5 

< .5 < .5 

< .5 < .5 < .5 

< .5 < .5 

< .5 < .5 < .5 < .5 < .5 < .5 

< .5 < .5 < .5 < .5 < .5 < .5 

< .5 < .5 < .5 < .5 < .5 < .5 

< .5 < .5 < .5 < .5 

Zn 

75 

140 

195 

210 

215 

215 

150 

145 

215 

185 

225 

205 

180 

155 

175 

225 

215 

70 

180 

140 

85 

155 

110 

130 

120 

130 

125 

85 

145 

80 

80 

80 

190 

185 

110 

110 

90 

95 

100 

100 

85 

60 

80 

140 

As 

20 

20 

10 

10 

10 

20 

20 

20 

20 

10 

10 

10 

10 

10 

10 

10 

20 

10 

20 

10 

10 

10 

20 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

10 

20 

10 

10 

10 

10 

10 

20 

20 

Cd 

4.5 

2 

2.5 

2 

1 

2 

1.5 

1 

1 

1 

1 

1 

.5 

1 

1 

1 

.5 

1 

.5 

1 

1.5 

1 

.5 

.5 

.5 

.5 

.5 

.5 

1 

.5 

.5 

1 

1 

.5 

.5 

1 

1 

1 

.5 

1 

1 

1 

1 

.5 

Cr 

60 

60 

80 

50 

70 

60 

60 

60 

50 

50 

50 

50 

60 

50 

60 

50 

60 

60 

50 

50 

60 

50 

60 

50 

50 

50 

50 

50 

50 

60 

40 

60 

80 

80 

50 

50 

50 

50 

100 

50 

60 

50 

50 

50 

<20-!Lm materials 

Cu 

95 

35 

40 

40 

45 

40 

35 

45 

60 

40 

40 

35 

40 

50 

50 

45 

55 

30 

70 

35 

40 

35 

35 

35 

35 

35 

35 

35 

35 

40 

35 

30 

95 

95 

45 

35 

30 

30 

55 

35 

30 

30 

40 

40 

Ph 

70 

35 

40 

40 

40 

35 

35 

40 

35 

25 

35 

40 

35 

90 

40 

25 

40 

20 

80 

20 

70 

20 

20 

20 

30 

35 

30 

20 

80 

40 

25 

10 

80 

120 

25 

20 

15 

15 

15 

35 

45 

25 

70 

40 

Hg 

0.90 

.11 

.13 

.09 

.10 

.03 

.07 

.14 

.12 

.03 

.03 

.22 

.31 

.34 

.18 

.05 

.20 

.19 

.16 

.11 

.31 

.26 

.16 

.27 

.24 

.05 

.26 

.29 

.08 

.09 

.05 

.09 

.12 

.09 

.02 

.38 

.31 

.25 

.10 

.29 

.13 

.30 

.17 

.10 

Ag 

1.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

1 

1 

1 

1 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

1 

1 

1 

.5 

.5 

.5 

.5 

.5 

4.5 

3 

1 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

.5 

Zn 

460 

270 

340 

350 

340 

340 

370 

310 

315 

260 

315 

335 

260 

445 

395 

470 

1215 

135 

475 

295 

245 

215 

210 

175 

185 

145 

140 

130 

165 

140 

125 

135 

185 

185 

130 

145 

130 

115 

130 

160 

175 

145 

120 

120 

1Samples collected September 18-29, 1973. All analyses by atomic absorption spectrophotometry and,co_lo:imetry .. •Concentrations are in units of milligrams of metal per kilogram dry sediment which equals parts per m1lhon by weight (ppml. 3Numbers refer to river-mile locations. 4The <2-mm materials include the <20-!Lm fraction. 

in only a few samples. The emission spectrographic data are presented in the appendix of 

Chapter F and are referred to briefly in the following discussions. 

DISTINCTION BETWEEN NATURAL 

BACKGROUND AND POLLUTION 

If trace metals in Willamette sediments represented only natural or unpolluted conditions, the 

concentrations might be expected to follow either 

a normal or a log-normal distribution (Levison, 

197 4). Furthermore, because the fine bottom sediments are derived primarily from the weathering of two chemically related rock types (andesite 

and basalt), the natural concentrations of the 

metals might be expected to be distributed as one 

statistical population. 

To test these assumptions and to distinguish 

polluted from unpolluted conditions, the concentrations of chromium, copper, lead, mercury and 

zinc in the <20-J,tm materials were plotted on 

probability papers according to the method described by Velz (1970, p. 522-542). Plots were not 

prepared for arsenic, cadmium, nor silver because 

the determined concentrations were uniformly 

low (see table 6). In preparing the plots, the Columbia River sample was excluded, providing a 

total of 43 data points (concentrations) for each 

metal. 

Examination of the completed plots showed 

that the metal concentrations more closely conformed to a normal rather than a log-normal distribution. Normal-probability plots were thus 

used as the basis of the interpretive approach, 

and the most interesting results were obtained for 

zinc, lead, and copper. 

M41 
TABLE ?.-Geographic distribution oftrace-metal concentrations in the <2~f.Lm materials of bottom sediments from the 

Willamette River and adjacent waters 1 

[Concentrations in parts per milhon] 

Mam stem Willamette River 

Metals 

Arsenic: Range _________ _ 

Average _______ _ 

Cadmium: Range _________ _ 

Average __ _ 

Chromium: Range _______ _ 

Average _______ _ 

Copper: Range _________ _ 

Average _______ _ 

Lead: Range _________ _ 

Average _______ _ 

Mercury: Range _________ _ 

Average ______ _ 

Silver: Range _________ _ 

Average _______ _ 

Zinc: Range _________ _ 

Average _______ _ 

All Willamette 

River 

basin 

samples 

1412 

10-20 13 

0.5-2.5 

1.0 

40-100 

57 

30-95 42 

10-120 

38 

0.02-0.38 0.16 

0.5-4.5 

0.8 

115-1295 249 

Main 

stem, 

river miles 0-187 

13112 

10-20 12 

0.5-2.5 

1.0 

50-80 55 

30-70 39 

10-90 

35 

0.03-0.38 0.18 

0.5-1.0 

0.6 

115-1295 

269 

Tidal 

Reach, 

river miles 0-26.5 

11412 

10-20 13 

0.5-2.5 

1.2 

50-80 

57 

35-70 45 

25-90 43 

0.0~0.34 

0.14 

0.5-1.0 

0.6 

260-1295 419 

Newberg 

Pool, river miles 26.5-52 16)2 

10-20 12 

0.5-1.0 

0.7 

50-60 

52 

35 

20-35 24 

0.05-0.27 0.18 

0.5-1.0 

0.7 

145-295 

204 

Upstream 

Reach, 

river miles 52-187 

111)2 

10-20 12 

0.5-1.0 

0.9 

50-60 

53 

30-40 34 

10-70 

30 

0.09-0.38 0.23 

0.5-1.0 

0.5 

115-175 

140 

Off river sloughs and Tributaries3 channels• 

10-20 

12 

0.5-1.0 

0.8 

40-100 62 

30-55 40 

15-70 34 

0.05-0.31 0.15 

0.5 

120-245 

151 

10-20 

18 

1.0-2.0 

1.4 

50-60 55 

35-60 41 

35-80 46 

0.07-0.12 0.10 

0.5 

165-370 

280 

Fourth 

Lake5 

10 

0.5-1.0 

0.7 

50-80 

70 

45-95 

78 

25-120 75 

0.02-0.12 0.10 

1.0-4.5 

2.8 

130-185 

167 

Columbia 

River6 

20 

4.5 

60 

95 

70 

0.90 

1.5 

460 

11ndividual values reported in table 6. 2Number of samples. 3Samples 19, 21, 31, 39, and 44. 

•samples 2, 7, 9, and 29. 5Samples 33, 34, and 35. 6Sample 1. 

ZINC 

The normal-probability plot of zinc concentrations ( <20 J.tm) defines a two-stage curve with a 

sharp break at 145 ppm (fig. 21a). The lower segment of the curve represents 15 samples and the 

upper segment 27 samples; the value of 1,215 

ppm at RM 21.1 (table 6) stands by itself far off 

the upper end of the scale. 

From foreknowledge of the potential sources of 

zinc pollution (see table 5), it was expected that 

samples collected downstream from the pulp mill 

at RM 49.2 would show higher concentrations 

than those taken from farther upstream. This is 

confirmed by figure 21A, because all the 15 samples represented by the lower segment were collected above RM 50. The concentrations of these 

samples were replotted in figure 21B, and a welldefined normal distribution was formed, as evidenced by the straight-line fit. 

Spatially, the increased levels of zinc in the 

Newberg Pool and the Tidal Reach correspond to 

the locations of the three ground-wood pulp mills 

(compare tables 5 and 6). The especially high concentrations between RM's 25.6 and 11.7 were 

below the outfalls of the two mills located between RM's 27 to 28. 

The combined knowledge of zinc sources and 

concentrations indicates that the lower segment 

in figure 21A represents natural background conditions, whereas the upper segment represents 

polluted conditions. The spatial distribution of 

concentrations precludes the possibility that the 

two-stage curve results from areal differences in 

geochemistry. 

LEAD 

Lead concentrations (in <20-~-tm materials), 

like those of zinc, define a two-stage curve when 

plotted on normal probability paper (fig. 22A). The 

lower curve includes concentrations from 10 to 40 

ppm and the upper curve concentrations from 45 to 

120 ppm. As with zinc, the levels included on the 

upper segment seem to represent pollution. 

In contrast to zinc, the enriched lead concentrations occurred at discrete locations (table 6), 

rather than in a large downriver zone. Most of the 

lead-enriched sites were in urban areas, suggesting that the pollution resulted largely from storm 

M42 
z 

0 

_..J 

_..J 

~ 

a: 

w 

Cl. 

Cf.) 

1-

a: 

<( 

Cl. 

z 

z· 

0 

i= 

<( 

a: 

1-

z 

w 

u 

z 

0 

u 

u 

z 

N 

500 

400 

300 

200 

100 

160 

140 

120 

100 

1215 PPM (RM 21.1) 

(A) ALL WILLAMETTE RIVER BASIN SAMPLES 

River mile locations are identified 

for polluted samples. 

0 (Multnomah Channel) 

Lake, 

Middle-Fourth Lake) 

(B) UNPOLLUTED SAMPLES 

80 ~---L----~--------~--~-L-L-L~~--~--~------~----------~ 

0.01 0.1 10 50 90 99 99.99 

PROBABILITY (PERCENT) EQUAL TO OR LESS THAN 

FIGURE 21.-Normal-probability plots of zinc concentrations in less than 20-,u.m materials. 

drainage off streets and roads (see table 5). The I the storm drainage zone of the Eugenehigh-concentration site at RM 185.3 was within Springfield area, and the sample at RM 161.2 was 

M43 
z 

0 

..J 

..J 

:::;: 

a: 

w 

0.. 

en 

~ 

a: 

<( 

0.. 

~ 

..J 

<( 

~ 

w 

:::;: 

110 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

90 

w 80 (.) 

<( 

a: 

~ 

70 

60 

50 

40 

30 

20 

River mile locations are identified 

for polluted samples. 

(A) LEAD 

(RM 25.6, Boise Cascade Slough, 

Head-Fourth Lake) 

River mile locations are identified 

for polluted samples. 

(B) COPPER 

(RM 185.3, Tualatin River) 

0 (RM 161.2) 

(RM 1.5, 6.0, 17 .0, 

Fourth Lake near 

confluence) 

10 ~--~----~-------L--~-L-L-L~_L~ __ _L ______ _L ________ ~ 

0.01 0.1 10 50 90 99 99.99 

PROBABILITY (PERCENT) EQUAL TO OR LESS THAN 

FIGURE 22.-Normal-probability plots oflead and copper concentrations in less than 20-~tm materials. 

M44 
collected near the highway bridge at Harrisburg. 

In the Tidal Reach, the samples at both RM's 25.6 

and 11.7 were collected just below bridges which 

cross the Willamette. 

Other lead-enriched samples were collected 

from Fourth Lake, Boise Cascade Slough, and the 

Tualatin River. Boise Cascade Slough receives 

garbage dump leachate which may account for 

the elevated lead concentration. Also, the elevated lead content of the Tualatin River sample is 

consistent with the high degree of urban development in the basin. 

Comparison of data in table 6 with possible pol· 

lution sources noted in table 5 indicates that all 

lead concentrations >25 ppm are from sites that 

receive either urban runoff or storm drainage 

from roads. Thus, although the probability plot 

suggests that lead concentrations from 10 to 40 

ppm are from one population, the comparison 

suggests that concentrations >25 ppm might constitute pollution. Moreover, as described in Chapter F, such a delineation is more consistent with 

lead concentrations in Willamette River basin 

soils. 

Geographically, if we use the 25-ppm value as a 

breakpoint, zones of lead enrichment occur 

around Newberg (samples 25 to 27) and in the 

Tidal Reach (all Tidal Reach samples except RM 

17.0). As noted in table 5, the Tidal Reach receives street runoff below RM 27.5, either in the 

form of urban storm drainage or combined sewer 

overflows. Samples 25 and 26 from near Newberg 

were collected from a subreach which receives 

urban runoff. In addition to the two zones, lead 

enrichment would be designated at RM 86.7 

(sample 30), which is adjacent to a highway, and 

at RM 141.3 (sample 40), which is just below the 

village of Peoria. 

The 25-ppm breakpoint seems to be reasonable 

because all samples designated as enriched (;::::30 

ppm) were collected from sites which received 

urban drainage. In contrast, nearly all samples 

designated as unpolluted (lead concentrations 

~25 ppm) were collected from locations which 

were away from the direct influence of urban 

drainage. 

COPPER 

The plot of copper concentrations on normal 

probability paper is best fitted by a two-stage 

curve (fig. 22B). The geographic locations of samples on the upper curve are suggestive of pollution. The locations include Fourth Lake (3 samples), the Marys River, a zone between RM's 11.7 

and 25.6 (samples 14, 15, 16, 17, and 19 in table 

6), and Swan Island Channel plus the immediate 

downstream site (RM 6.0). The Marys River sample also contained relatively high concentrations 

of chromium, cobalt, nickel, and vanadium (see 

Chapter F). The high copper concentrations between RM's 11.7 and 25.6 coincide with the zone 

of high zinc concentrations (fig. 21A), and with 

elevated levels of lead (fig. 22A). The cause of the 

elevated copper concentrations in this zone is unknown, but possible sources (table 5) include 

municipal secondary effluents in addition to the 

urban drainage and the pulp and paper mill effluents. 

FOURTH LAKE 

The sediments from sites 33 and 34 in Fourth 

Lake were oily, black, odorous, and composed entirely of clay and silt-sized materials. In contrast, 

sample 35, collected near the confluence of Fourth 

Lake with the Willamette, showed indications of 

mixing with coarse river sediments. In reporting 

the trace-metal data (table 8), the concentrations 

at sites 33 and 34 are averaged, and the values at 

site 35 listed separately. For comparison, table 8 

also lists the average and model concentrations of 

each metal in the other Willamette River basin 

samples. 

Table 8 indicates that the Fourth Lake samples 

were polluted by a large number of metals. Of the 

total list of enriched metals, the following 12 can 

be associated with processes at Teledyne-Wah 

Chang (see section ttPossible Sources of Trace 

Metals"): chromium, hafnium, lanthanum, 

molybdenum, nickel, niobium, scandium, silver, 

tin, ytterbium, yttrium and zirconium. 

Arsenic, copper, lead, mercury, and zinc were 

also enriched, but the sources of these metals are 

unknown. The arsenic and mercury enrichments 

occurred only in the <2-mm materials. 

Although Fourth Lake was heavily polluted, 

the sample (32) collected just downstream at RM 

112.6 (table 6) showed no enrichment of any of the 

listed metals. Moreover, none of the special metals discharged by Teledyne-Wah Chang were determined at enriched levels in any downstream 

sample. Thus, it appears that metals discharged 

into Fourth Lake precipitate and stay within the 

slough, at least under low-flow conditions. If the 

metals do flush from the slough at high flows, 

they must (1) flush entirely from the basin, (2) be 

diluted to background levels, (3) be annually 

buried at depths greater than those sampled in 

the study (improbable), or (4) be affected by some 

M45 
TABLE B.-Concentrations, in parts per million, of trace metals in Fourth Lake 

Metal 

Arsenic _____ _ 

Cadmium ___ _ Chromium ___ _ 

Copper _______ _ Lead _________ _ 

Mercury _____ _ 

Silver _______ _ Zinc _________ _ 

Arsenic 

Cadmium ___ _ 

Chromium ___ _ Copper _______ _ Lead _________ _ 

Mercury _____ _ 

Silver _______ _ Zinc _________ _ 

Atomic absorption spectrophotometry and colorimetry 

Average of 

samples 33 

and34 

Average for other Willamette River 

Sample 35 basin samples1 

<2-mm materials 

50 

1.0 

85 

30 

83 

.462 

<.5 

188 

<10 

.5 

80 

15 

15 

.16 

<.5 

110 

<2~JLm materials 

10 

.8 

80 

95 

100 

.10 

3.8 

185 

10 

.5 

60 

45 

25 

.02 

1.0 

130 

12 

.6 

74 

10 

16 

.15 

<.5 

142 

13 

1.0 

57 

42 

38 

.16 

.8 

249 

1 Forty samples (excluding Columbia River sample!. 2Th1s value is dominated by the concentration of 0.80 ppm in sample 34. 

combination of these possibilities. Further work 

is needed to determine if Fourth Lake is actually 

a year-around sink of incoming metals and, if so, 

whether the capacity for storage is still very large 

or possibly nearing its limit. 

SUMMARY AND CONCLUSIONS 

Trace-metal concentrations determined in this 

study iri.dicated a clean environment with the exception of a moderate enrichment of zinc, slight 

enrichment of copper and lead, and pollution by 

several metals in Fourth Lake. 

The zinc enrichment resulted primarily from 

use of zinc hydrosulfite as a brightening agent in 

three ground-wood pulp and paper mills. As aresult of orders from the Oregon DEQ, the mills will 

cease using zinc hydrosulfite by July 1977. The 

lead enrichment appeared to be tied directly to 

urban drainage, but no specific source was identified for copper. Fourth Lake, an industrial 

slough, showed enrichment of 15 elements including uncommon metals such as zirconium, hafnium, yttrium, ytterbium, and tin. However, 

none of these metals was present in enriched concentrations at any downstream site. 

The study results suggest that no metals were 

present in the Willamette River at concentrations 

which might represent an immediate ecological 

threat. However, from a resource management 

Em1ssion spectroscopy 

Range of Modal value for 

other Willamette Metal samples 33 and 34 Sample 35 River basin samples 

<2~J.tm materials 

Hafnium -----· 500-700 

Lanthanum____ 50 

Molybdenum -• 7-10 

Nickel ________ 50 

Niobium ______ 200 

Scandium ____ 50-70 

Tin __________ 150-200 

Ytterbium ____ 20-50 

Yttrium ______ 200-300 

Zirconium ____ 15,000-20,000 

150 

<50 

3 

50 

70 

50 

20 

15 

70 

7,000 

<100 

<50 

<3 

30 

<10 

30 

<10 

3 

30 

200 

standpoint, further studies are needed to determine (1) how zinc concentrations in the Tidal 

Reach respond to the ban on zinc hydrosulfite, (2) 

the amount of lead entering the river in urban 

drainage and combined sewer overflows, and (3) 

the ultimate fate of metals discharged to Fourth 

Lake. Answers to these questions still will not 

define the relationship of trace-metal concentrations in Willamette sediments to possible longrange potentials for toxic effects. It is hoped that 

basic knowledge of aquatic ecosystems will advance rapidly in the near future so studies can be 

initiated in the Willamette and in other United 

States rivers to assess this critical relationship. 

IMPACT OF LAND-USE ACTIVITY ON 

EROSION AND DEPOSITION 

BACKGROUND 

The Willamette River at high flow is sediment 

laden, and 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 water treatment, 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 gullies, landslides, and 

M46 
streambank failures. Such deformations often 

ruin the land for further intended use and result 

in large costs for clean-up and restoration. The 

deformations also release additional quantities of 

sediment to tributary streams and thus eventually to the mainstem of the river. 

Projections for the Willamette River basin indicate a great increase in population and industry 

over the next 50 years. Large acreages of land 

now in forest and agricultural use will be urbanized. In addition, vast areas of forest land will 

be logged for Oregon's pulp and paper industries. 

The potential impacts of these activities on land 

and river quality have not been appraised. 

The quality of a river is largely determined by 

the interaction between climate, basin-terrain 

characteristics, and land-use activity. At present, 

the controlling interrelationships are poorly defined because of (1) inadequate recognition of the 

linkages between land-use activity and river 

quality and (2) until recently, lack of a suitable 

basis for synoptic terrain analysis of entire river 

basins. 

In the Willamette River basin, an integrated 

assessment is urgently needed of how different 

land uses affect the quality of water resources. 

The first requirement of such an assessment is a 

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

ASSESSMENT APPROACH 

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 interpretive mapping and derived from approaches 

used to delineate erosional problems in the San 

Francisco Bay area (Brown and Jackson, 1973 

and 1974). 

The premises of the procedure were: (1) climate 

and terrain properties determine the potential 

erodibility of land in its natural state, (2) land-use 

activities represent cultural disruptions of terrain surfaces, and (3) different combinations of 

terrain properties and land-use activities result 

in different types and severities of erosional-

.depositional problems. The procedure was used to 

first produce an erosional-depositional province 

map and then to prepare an erosional-impact 

matrix for direct use by basin planners. Details of 

the procedure are given in Chapter L, and its subsequent application to the Willamette River basin 

is described in a report presently being prepared 

under the direction of J. D. Meyers (referenced 

here as a written communication because it has 

not been approved for publication). 

As a basis for developing the map and matrix, 

an up-to-date photomosaic base was needed at a 

scale suitable for recognition of natural and altered surface-cover conditions. The scale selected 

for the regional scope objectives of this study was 

1:130,000 (see Chapters C and L). The mosaic was 

prepared from high altitude photographs taken 

by the U.S. National Aeronautics and Space Administration (NASA) during July 1973. 

DEVELOPMENT OF THE EROSIONAL-DEPOSITIONAL 

PROVINCE MAP 

COLLATION OF CRITICAL TERRAIN FACTORS 

A small section of the basinwide erosionaldepositional province map is shown in figure 23. 

The first step in producing the map was to select 

carefully and then integrate the physical factors 

that exert the greatest control on terrain-surface 

stability. This work was based on the province 

concept as formulated by Brown and Jackson 

(1973 and 1974). 

THE PROVINCE CONCEPT 

As noted in the ((Geologic Overview," the Willamette River basin can be divided into three 

north-south physiographic units: the Cascade 

Range, the Coast Range, and the Willamette Valley. These units can be considered as large 

erosional-depositional provinces, with the Coast 

Range on the western side and the Cascade Range 

to the east being dominated by erosional processes, and the centrally located Willamette Valley 

dominated by depositional processes. 

For our purposes, these regional physiographic 

divisions were further subdivided for better definition of erosional cause-effect phenomena and for 

application to environmental planning. The delineation process was based on development of 

criteria for identifying distinctive erosional and 

desposi tional provinces. 

PROVINCE CRITERIA 

The criteria for delineating erosionaldepositional provinces were based on the deM47 
EXPLANATION 

---- Basin boundary 

-- Province boundary 

Erosional-depositional provinces 

c. 

c2 

I 1 (see table 9 for 

I 2 explanation) 

v. 

Y2 

Erosional features 

R- Rill and sheet E- Earth flow or debris flow L-Landslide 

T- Talus 

Depositional features 

s- Streambed deposits M- Marshland 

Manmade features 

x- ExcaYation 

Basin 

INDEX MAP OF OREGON 

I 

N 

I 

12T'30' 

APPROXIMATE SCALE 1:130,000 Uncontrolled photomosaic bate prepared by 

U.S. Geologie~~! Survey. Photogrephs tlken 

July 1973 by U.S. National Aeronautk:s 1 2 3 4 MILES 

I KILOMETRES and Space Administration. 

FIGURE 23.-Erosional-depositional provinces in part of the Molalla River subbasin, Oreg. 

velopment of hypotheses concerning the controlling influence of different physical factors on 

terrain-surface stability. The investigated factors 

were vegetation, precipitation and runoff, soils, 

geology, and slope. 

The hypotheses for evaluating these factors 

were tempered by four overriding considerations: 

(1) the primary objective of the study as a regional overview of the major processes and problems of the sediment system, rather than as a 

comprehensive geomorphic investigation suited 

for site-specific interpretations, (2) the need for a 

simple, practical product that is understandable 

by planners and compatible with the 1:130,000-

scale photomosaic base, (3) the large variability 

in quality, quantity, and scale of existing earthresource data and maps, and (4) the extensive 

background of observations, publications, and 

knowledge concerning the functions, relationships, and relative importance of the major factors affecting the sediment system. 

In concert, these four considerations dictated 

that the hypotheses be (1) general and not overly 

concerned with minor terrain anomalies and special, localized conditions, (2) suited to the identification of a small number of erosional and depositional mapping units (not more than ten) so as to 

minimize confusion and clutter on the photomosaic base, (3) compatible with the quality, 

quantity, and resolution of available earthresource information, and (4) consistent with accepted scientific fact and reason. 

Each of the developed hypotheses is briefly 

stated below. (Detailed descriptions are provided 

in Chapter L with regard to rationale, substantiation, qualifications, and possible refinements.) 

Vegetation.-The extensive surface cover and 

soil-holding characteristics afforded by natural 

vegetation allow only minimal erosion. Only 

when vegetation is removed by man's land-use 

activities can severe erosional problems develop. 

Precipitation and runoff.-As to their regional impact on the sediment system, the precipitation and runoff regimes can be considered generally constant throughout the Willamette River 

basin. 

M48 
Soils.-Insofar as susceptibility to erosion is 

concerned, the soils of the Willamette River basin 

are considered generally homogeneous. The exception is the highly erodible soils developed on 

the geologically defined lacustrine and loessial 

Upland Silt Deposits (see below). 

Geology.-For purposes of this study, the valley 

floor of the Willamette River basin was considered an area dominated by depositional processes 

and was classified into two basic categories: the 

Valley Floodplain Alluvium and the Valley Terrace Alluvium. The upland area of the Willamette basin consisting of the valley buttes, 

foothills, and mountains of the Coast and Cascade 

Ranges is dominated by erosional processes and 

was classified into three basic categories according to the susceptibility of the rock units to fluvial 

erosion and mass wasting. The three categories 

are: The Upland Silt Deposits, which locally mantle the buttes and foothills of the northern part of 

the valley; the Incompetent, or weakly coherent, 

Bedrock units, which are prone to slope failure; 

and the Competent, or strongly coherent, Bedrock 

units, which make up the higher ridges and steep 

peaks of the mountain areas. 

Slope.-A slope of 12 percent demarks the approximate boundary between upland terrain, that 

is predominantly erosional, and lowland terrain, 

that is predominantly depositional. This criterion 

was used to distinguish two erosional provinces in 

each of the three upland geologic categories. 

Thus, on the basis of the stated hypotheses, 

geology and slope were determined to be the critical criteria for defining erosional-depositional 

provinces. These two factors were used to identify 

the six erosional and two depositional provinces 

defined in table 9. 

PROVINCE DELINEATION 

From the defined criteria for geology and slope, 

the six erosional and two depositional provinces 

(table 9) were delineated throughout the Willamette River basin. As an example, figure 23 includes the two depositional provinces (V1 and V2 ) 

and four of the six erosional provinces (ll' ~' cl' 

and C2). 

The eight provinces were delineated using the 

overlay approach. First, generalized geologic and 

soils maps of the basin were optically enlarged 

and scale matched to the photomosaic base (Vickers and others, 1976). Floodplain and terrace alTABLE 9.-Erosional~epositional provinces delineated in the 

Willamette River basi_n, Oreg. _ 

Map symbol Geologic group 

Erosional provinces 1 

Upland Silt Deposits: 

Slope 

(percent! 

Sloping uplands ________________ <12 

Steep uplands __________________ >12 

Incompetent Bedrock: 

Sloping uplands ________________ <12 

Steep uplands __________________ >12 

Competent Bedrock: 

Sloping uplands ________________ <12 

Steep uplands __________________ >12 

Depositional provinces 

Valley Alluvium: 

V 1 Floodplains -------------------- <3 

V 2 Terraces________________________ > 12 

'Erodibility increase from umt C2 through S 1 

luvium units were then outlined to identify the 

two depositional provinces. Next, the Upland 

Silts and the Incompetent and Competent Bedrock groups were outlined. Finally, a scale 

matched slope map was used to separate the Silt, 

Incompetent, and Competent units into <12 and 

> 12 percent slope groups. 

Throughout the overlay procedure, aerial photographs and 1:24,000- and 1:62,500-scale topographic maps were used to make adjustments to 

province boundary lines. This was necessary because slope and geological information was 

generalized from maps of various scales that did 

not strictly conform with the semicontrolled 

1:130,000 photomosaic base. For this reason, the 

erosional-depositional provinces in figure 23 (and 

on the basinwide map) are regional in nature. 

MAPPING OF EROSIONAL-DEPOSITIONAL 

FEATURES 

The second step in producing the map was the 

delineation of existing erosional-depositional features. The continual erosion, transport, and deposition of sediment in the basin is manifested 

most dramatically by formation of features such 

as gullies, landslides, and streambed deposits. 

The location, density, and size of such features 

provides visual verification of the interaction of 

critical terrain factors with land-use activities. 

Figure 23 shows the location of active erosional 

and depositional features in part of the Molalla 

River basin (subbasin of the Willamette) as idenM49 
tified from false-color, infrared (IR) aerial photographs. In the map of the entire basin, three 

categories and 10 individual features are identified (table 10). These features are described by 

Meyers and others (written commun., 1976), and 

the technique by which the features were located 

and verified is presented in Chapter L. 

DEVELOPMENT OF THE 

EROSIONAL-IMPACT MATRIX 

The completed erosional-depositional province 

map with accompanying erosional and depositional features (see fig. 23) provides a basic tool 

for examining the basinwide condition of the sediment system. However, the map's utility for environmental planning was augmented through 

development of an erosional-impact matrix (table 

11.) The matrix provides a systematic basis for 

making predictive estimates of the relative impact, in terms of erosion, of human activity on 

different types of terrain (provinces). The horizontal axis is composed of weighting factors for 

slope and geology, and the vertical axis of weighting factors of selected land-use activities. The 

body of the matrix is composed of erosionalimpact ratings, ranging from <10-3 to > 103 , resulting from the product of the three sets of 

weighting factors. 

The rationale for developing the three erosional 

weighting factors and the subsequent erosional 

impact ratings is based on ( 1) the concept of 

order-of-magnitude differences in annual average 

sediment yield due to land use-terrain interaction (Judson, 1968) and (2) the universal soil loss 

equation (see Musgrave, 1947, and Chow, 1964). 

LAND USE EROSIONAL FACTORS 

Land-use activities in the basin were identified 

from field-checked interpretation of stereomagnified, false-color IR aerial photographs. Five 

major categories and 20 individual land-use activities (see table 11) were chosen on the basis of 

their prevalence and socioeconomic importance in 

the basin. For purposes of illustration, the activities comprising the categories of agriculture 

and forestry-logging are described in table 12 

along with their associated erosional factors. 

The erosional factors were assigned to each 

land-use activity on the basis of approximate 

order-of-magnitude differences in sediment-yield 

potential (Meyers and others, written commun., 

TABLE 10.-Erosional-depositionalfeatures mapped in the Willamette River basin, Oreg_ 

Feature Mapping symbol 

Erosional: 

Sheet and Till erosion ______________________ R 

Gully erosion ------------------------------ G Landslide ____ _________ _ ____ __ __ ________ _ ___ L 

Earth flow or debris flow ____________________ E 

Talus ______________________________________ T 

Streambank failure ________________________ B 

Depositional: 

Streambed deposit-------------------------- S 

~arshland -------------------------------- ~ ~anmade: 

Excavation -------------------------------- X 

Artificial filL_______________________________ F 

1976). The factors were derived from a review of 

pertinent quantitative studies (including some 

made in other river basins) and roughly represent 

order-of-magnitude rates for average sediment 

yields expressed in tons/acre/yr. As a basis for 

transferring the quantitative data from studies 

made outside the basin, it was necessary to compensate for differences in climate and soil type. 

Thus, in developing the sediment-yield estimates, 

the Willamette River basin was characterized as 

having a temperate marine west coast climate 

with annual precipitation of 35 to 80 in. (890 to 

2,030 mm) and a ((standard" clay loam soil that is 

permeable and moderately erodible. 

SLOPE AND GEOLOGIC 

EROSIONAL FACTORS 

The factors for slope and geology were derived 

in a similar manner to those for land use. In this 

case, the empirical judgments were based on (1) a 

review of available sediment yield data for the 

Willamette River basin; (2) observations of erosional phenomena by the U.S. Soil Conservation 

Service (Oregon State Water Resources Board, 

1969); and (3) photointerpretation of stereomagnified color IR photography to determine the 

occurrence and magnitude of different erosional 

features on different slope and geologic settings. 

For compatibility with the land use-erosional factors, order-of-magnitude numbers were assigned 

to each slope and geologic category included in 

the matrix (table 11). 

APPLICATION TO PLANNING 

In conjunction with the erosional-depositional province map, the completed matrix provides a means for making tentative estimates of 

M50 
~ 01 

...... 

TABLE 11.-Matrix for estimating interactive erosional impact of land-use activities with terrain properties of geology and slope, Willamette River basin, Oreg. 

Land-Use Activity 

Slope 

(percent) -------------- Slope·erosional 

factor ------------------ Geologic group1 ----------

Geologic.erosional 

factor ------------------ Product2 ------------- -----

Land use-erosional 

factor" 

Mature forest ________________ ___ _____________ --- __ --- _ 10., 

10., 

10 .. 10 .. 10 .. 10 ·I 

10 ·t 

10 ·I 

10 ·I 

10 ·I 

10 ., 

Managed silviculture or nursery ------- ---------------- Forest regrowth or mixed woods and shrubs Helicopter or ballon logging 

~:cth~~~~r~ <;~;~~&:,~~; -~- -------------------------- Pasture or grassland (light grazing) 

~~~~du:o~d~d(~~\~~~i:i~~n~~?t r~~~~~~~ 

~!!~erf~eg;(!iri ~-;i~i~~ ;~;; ~O~~f)- ---------------------

g~~h~~ddJi~h~~['iz.~u~d~~,;;; ~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

~~:~~~er~~g~ss!~~ -~ ~~~~:'-~~~~~~~ ~--------- ------ Tractor logging __ _________________________ ___________ _ 

Fallow agricultural land ------------------------------- Light construction and excavation ______________________ _ 

Temporary dirt roads (poorly maintained) 

Heavy construction and excavation 

'See table 9. 2Product of slope- and geologic-erosional factors. 3See table 12 for an example. 

10° 

10" 

10° 

10" 

10° 101 

101 

102 

102 

4Ratings are the product of land use-, slope-, and geologic-erosional factors. 

()...3 

10 .. 

V1/V2 

10" 10 .. 

< 10., 

< 10., 

< 10 ·3 

< 10., 

< 10., 

10., 

10., 

10., 

10., 

10 "3 

10 ·3 

10 .. 10 .. 

10"' 

10 .. 10 .. 

f(f"' 

10"1 

10° 

10° 

3-7 

10 ·I 

V2 /11 

10° 10 ., 

< 10 -3 

< 10 "3 

10., 

10 ·3 

10 -3 

10 .. 10 .. 10 .. 10 .. 10 .. 10 .. 

to ·• 10 ·I 

10 •I 

10 •I 

10 •I 

100 

10° 

101 

101 

c, 

10 ., 10 ·I 

< 10., 

< 10., 

10., 

10 ·3 

10., 

10 .. 

10 .. 10 .. 10 .. 

10 .. 

10 .. 10 ., 

10 •I 

10 •I 

10 ., 

10 ·t 

10" 

100 

101 

101 

7-12 

--

10° v,ti, 

10" to• 

s, 

101 

101 

c, 

10 ·I 

10" 

12-20 

101 

I, 

10" 101 

s. 

10' 

10' 

c, 

10 ., 

101 

2()...60 > 60 --

102 103 

I, s, c, I, 

10" 101 10 ·I 10° 

102 103 102 103 

Erosional impact rating4 

~ Ratings ofl0-2 or less reflect low erosional impact. 

Ratings from 10-1 tol0 1reftect moderate erosional impact. 

Ratings ofl 02 or greater reflect major erosional impact. 
TABLE 12.-Relative erosional factors associated with agricultural and forestry-logging activities, 

Willamette River basin, Oreg. 

Land-use activity 

Agriculture: 

Land use- erosional 

factor Remarks 

References utilized in deriving land use- erosional factor 

Fallow (bare soil) ___________ _ 

Cropland (row crops) _______ _ 

Orchard, without groundcover crop _____________________ _ 

Orchard, with groundcover crop _____________________ _ 10-1 

Fluvial erosion is cause of most sediment 

yield from agricultural areas, except on steeper lands (> 12 percent) used for or- chards and pasture where mass wasting 

may also be significant in areas of incompetent rock and unstable soils. 

Ursie and Dendy (1965); 

Wolman (1967). 

Pasture or grasslands (heavy grazing) ___________ _ 

Pasture or grasslands (light grazing) ___________ _ 

Forestry and logging: 

Ten-year old regrowth or mixed 

woods and shrubs (old logging 

roads partially overgrown) __ Mature forest (no roads) _____ _ 

Managed silva-culture, mature 

nursery ------------------ Tractor logging (10-20 lineal 

mi/mi2 oflogging roans) ---- Cable logging (1-4 lineal mi/mi2 

oflogging roads) __________ _ 

Helicopter or balloon logging 

(1 lineal mi/mi2 of logging 

roads) --------------------

10-2 

10-3 

10-1 

10-2 

Logging activities remove vegetation, disturb soils, artifically steepen slopes, and 

cause compaction in areas worked by 

tractors. Where logs are skidded, soil is 

laid bare, compacted, and channels 

formed for rapid runoff. Roads are the 

most disruptive of all logging practices, 

particularly in areas of incompetent rock 

and unstable soils. (Note that: the approximate sediment yields for logging are significantly lower than for construction. This apparent anomaly is due to our assumption, for comparative purposes, of a standard 7-12 percent slope.) Most logging activities occur on slopes between 

20 to 60 percent and consequently cause greater sediment yields per unit area than indicated here (J.D. Meyers and 

others, written commun., 1976). 

Ursie and Dendy (1965); 

Dyrness (1967); 

Fredricksen (1970) 

Megahan and Kidd (1972); 

Kid and Kochenderfer 

(1973) 

the erosional impact of human activities on various lands in the basin. The following sequence of 

steps provides a guide for using the map and matrix: 

(1) Locate the parcel of land for which a particular land-use activity, or set of activities, has been 

proposed. 

(2) Identify the province in which the proposed 

activity would occur and examine the prevailing 

patterns of land-use activities and erosional features. The existence, or absence, of erosional features and their type will indicate to some degree 

the possible magnitude of erosional impact in 

terms of land deformation that would be generated by the proposed change in land-use activity. 

(3) Note the prevailing geologic and slope conditions for the area in question by cross referencing (a) the province (for example,~) within which 

the parcel of land is enclosed with (b) the geologic 

and slope criteria shown in table 11. 

(4) Enter the matrix body under the specified 

combination of slope, geology, and land-use activity. Note the appropriate erosional-impact 

number or range of numbers. An impact rated 

below 10-1 indicates minimal potential for erosion; Impacts in the 10-1 to 101 range indicate that 

moderate to high erosion could be generated and 

hence that management and/or conservation 

practices may be required. Impact ratings of> 102 

indicate that high to extraordinary erosional impacts are likely to be generated and that the proposed land-use activity should be questioned. 

The erosional-impact ratings in table 11 were 

developed as guidelines for regional planning 

purposes. High impact ratings do not necessarily 

mean that a proposed land-use cannot be reasonably undertaken provided stringent conservation and engineering practices are applied. Final 

judgments as to land-use suitability, particularly 

for lands receiving ratings above 10\ should be 

based on detailed site investigations. 

SUMMARY AND CONCLUSIONS 

We believe that the map and matrix developed 

in this study provide the kind of framework 

needed to develop regional programs for quantitatively defining the effects of land management on river quality. The map is regional in scale 

and shows where erosional and depositional problems are most prevalent. Using the map, data 

programs can be spatially designed to better 

define the cause-effect relationships of land and 

river processes. The matrix provides the necessary collaborative information for selecting 

M52 
baseline and other comparative areas. Once the 

spatial framework of a data program is defined, 

the analysis of climate and streamflow records 

can be used to determine the optim urn timing and 

frequency of sampling. 

Thus, the erosion-potential map and matrix are 

useful tools for (1) immediate land-use planning 

and (2) the design of data and research programs. 

For both purposes, the tools are flexible, because 

through interpretation of aerial photography, 

they can be regularly updated to provide information under rapidly changing conditions. 

FURTHER STUDIES 

The Willamette assessment is the first of three 

prototype studies being conducted by the Geological Survey. The effects of urbanization on water 

quality are b~ing analyzed in the Chattahoochee 

River basin in Georgia, and the potential environmental problems of energy development are 

being assessed in the Yampa River basin in 

Colorado-Wyoming. In both studies, information 

will be developed for assessing specific basin problems. However, as in the present study emphasis 

will be placed on developing flexible methodologies and data programs that can be used 

throughout the country. 

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M55