Hydrologic Analysis and 

River-Quality Data Programs 

By Walter G. Hines, David A. Rickert, and 

Stuart W. McKenzie 

RIVER-QUALITY ASSESSMENT OF THE WILLAMETTE RIVER BASIN, OREGON 

GEOLOGICAL SURVEY CIRCULAR 715-D 

1976 
United States Department of the Interior 

THOMAS S. KLEPPE, Secretary 

Geological Survey 

V. E. McKelvey, Director 

Library of Congress Cataloging in Publication Data 

Hines, Walter G. 

Hydrologic analysis and river-quality data programs. 

(U.S. Geological Survey Circular 715-D) 

Bibliography: p. 12. 

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

1. Rivers-United States. 2. Water quality-United States. I. Rickert, David A., 1940-

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

States Geological Survey Circular 715-D. 

QE75.C5 no. 715-D [GB1215] 557.3'08s [628.1'61] 76-608289 

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

The American public has identified the enhancement and protection of river 

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

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

improvements will require substantial expenditures and the consumption of 

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

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

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

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

in the Willamette River basin, Oregon. 

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

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

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

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

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

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

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

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

land and water uses. 

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

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

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

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

scientific validity. 

Individual circulars will be published in an alphabetical sequence in the 

Geological Survey Circular 715 series entitled 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 

Foreword ____________________________________________ III 

Abstract_ _____________________________________________ D1 

Introduction ________ _____ _ _______ _ __ __ ____ _ _________ __ 1 

Purpose and scope ------------------------------- _ 2 

Acknowledgments -------------------------------- 2 

Critical temporal and spatial aspects of river-quality problems ----------------------------------------- 2 

Dissolved-oxygen depletion ------------------------ 3 

Excessive algal growth---------------------------- 5 

Toxicity ______ __ ______ _ _ ________ ________ _ ________ _ 5 

Salinity __ __ _ _ ____ _ _ _ _ __ _ _ ______ _ _ _ _ ____ _ _ _ _ _ _ _ _ __ 5 

Thermal pollution -------------------------------- 6 

Microbial pollution________________________________ 6 

Sedimentation and turbidity ______________________ 6 

Generalizations ------------------------------------ __ 6 

Page 

Discussion ________________________ ------ ____ ---_------D7 

The "shotgun" approach -------------------------- 7 

An alternative to routine monitoring ______________ 7 

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

Reinterpretation of existing quality data ______ 9 

Repetitive synoptic studies ____________________ 9 

Drought studies --------------------------10 

Flood studies ----------------------------11 

Summary --------------------------------------------11 

References cited ______________________ ----------------12 

Supplemental information ----------------------------12 

Quantification of river hydrology for quality analysis 12 

Quantification of streamflow ----------------------12 

Low flows ------------------------------------15 

Highflows------------------------------------16 

Quantification of water ternperature----------------16 

Quantification of channel morphology --------------17 

ILLUSTRATIONS 

Page 

FIGURE 1. Diagram showing relation of immediate, generative, and extra environments to river-quality _______________ D1 

2. Graphs showing Willarnette River discharge at Salem, Oreg., 1944, 1964 and 1973 water years _____________ 13 

3. Map of Willarnette River basin, Oreg., emphasizing main stern, tributaries, and reservoirs ----------------- 14 

4. Sine curve for representing river temperature patterns ------------------------------------------------- 16 

5. Graph showing mean monthly and maximum and minimum daily water temperatures for the North Santiarn, 

Willarnette, and South Yamhill Rivers, Oreg __________________________________________ ------------ 17 

6. Seasonal pattern of surface water temperature for the Olentangy River, Ohio ---------------------------- 18 

7. Map and diagram representing the Willarnette River, Oreg., showing distinctive morphologic reaches and 

elevation profile ---------------------------------------------------------------------------------- 19 

8. Cumulative time-of-travel for various low flows, Willarnette River, Oreg --------------------------------- 20 

TABLES 

Page 

TABLE 1. Selected characteristics of common river-quality problems ---------------------------------------------- D4 

2. Lowest daily discharge for 7, 14, and 30 consecutive days in year ending March 31 for Willarnette River at 

Salem, Oreg., 1910-70 ____ --------------------------------------------------------- _______________ 15 

CONVERSION FACTORS 

[Factors for converting English units to the International System of Units <SIJ 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./s (inches per second)---------------------

ft3/s (cubic feet per second) _________________ _ 

RM (river miles)----------------------------

rni (miles)----------------------------------

Multiply by Metric (8]) 

2.540 ____________ cm/s (centimetres per second) 

2.832 x 10-2 ____ rn31s (cubic metres per second) 

1.609 __________________ RK (river kilometres) 

1.609 ________________________ krn (kilometres) 

v 

Hydrologic Analysis and 

River-Quality Data Programs 

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

ABSTRACT 

In many basins it has proven difficult to use existing riverquality data for analysis of the temporal and spatial trends 

and the major cause-effect relations that control critical quality conditions. Major reasons for this problem are the arbitrary nature of sampling programs that generate the quality 

data and a general failure to account for the background variability in quality resulting from hydrologic phenomena. 

A review of prominent river-quality problems of the Nation's rivers shows that the timing, location, and frequency of 

occurrence of the problems are largely controlled by three 

hydrologic characteristics-streamflow, water temperature, 

and channel morphology. These characteristics show marked 

variation from river to river and, thus, must be systematically 

accounted for if river-quality data are to become more useful 

for interpretive purposes. An approach to river-quality data 

programs based on hydrologic analysis and repetitive synoptic 

studies is proposed as an alternative to current approaches 

that rely heavily on routine monitoring. 

INTRODUCTION 

Population growth and associated urban, 

industrial, and agricultural development have 

caused severe environmental stresses on the land 

and water resources of the Nation's river basins. 

An important aspect of long-range environmental 

planning is the understanding and quantification 

of man's impacts on the quality of rivers. Perhaps 

justifiably, in light of the complexities involved, 

enormous amounts of time, money, and effort are 

expended on river-quality sampling programs. In 

many basins, however, years of quality sampling 

have not generated adequate information from 

which to establish environmental standards or to 

make sound resource decisions. This situation has 

resulted in a growing dissatisfaction with riverquality data programs. 

In a discussion cealing with water-quality 

sampling, Howells (1971, p. 166) said the following about existing monitoring practices: 

Dl 

A few monthly samples taken without regard to rainfall, 

stream flows, and vagaries in waste loads say very little about 

the quality of a stream, and it would be well to stop deluding 

the public that present monitoring systems mean very much 

at all. The time is long overdue for a good hard look at 

monitoring programs. 

In a similar vein, Deininger (1974) stated: 

Despite the fact that water quality monitoring programmes 

form the basis for all abatement and investment programmes, 

there is little evidence that they are being designed on a rational basis, rather they are designed on an ad hoc, emergency 

type, basis. 

In a landmark paper on the quality of the Nation's rivers, Wolman (1971, p. 905) cited a 

chronic inability to use available data for analyzing trends and cause-effect relations: 

adequate comparisons of specific variables related to water 

and to river quality require systematic correlation with hydrologic behavior. Such correlations are rarely available ... a 

knowledge of the "natural background" or temporal variability of a given parameter is often essential in detecting and 

measuring a trend. Statistically, a trend cannot be discerned 

unless it is possible to discriminate between the variability of 

the phenomenon as it might occur unaffected by the influences 

that one wishes to measure, in this case so-called pollution, 

and the variability normally associated with diurnal, annual, 

and significant secular climatic variations that occur in the 

hydrologic record over any period of time. 

On the basis of experience with numerous rivers and estuaries in the United States, Velz 

(1970) concluded that a thorough understanding 

of the hydrologic regimen of rivers is an essential 

prerequisite for interpreting river-quality behavior and, thus, for formulating mathematical 

river-quality models. 

The work of Howells, Deininger, Wolman, and 

V elz points to two prominent shortcomings in 

many quality sampling and analysis programs: 

1. The arbitrarily derived, fixed temporal and 

spatial design of sampling programs from 

which quality data are derived. 
2. A failure to account adequately for the seasonal and reach-to-reach variability of river 

quality that results from hydrologic 

phenomena. 

PURPOSE AND SCOPE 

The purpose of this circular is to present ideas 

for improving the interpretive worth of riverquality data for environmental decisions. The 

main part of the circular covers two topics. The 

first deals with critical temporal and spatial aspects of seven prominent river-quality problems. 

Several important generalizations relating river 

quality to hydrologic phenomena are derived 

from this discussion. The generalizations form a 

framework for the second topic which is a discussion of deficiencies in recent river-quality data 

programs and the proposal of an alternative program for correcting the deficiencies. 

The circular also contains a supplemental 

section CQuantification of River Hydrology for 

Quality Analysis") that presents examples and 

methodologies useful for analyzing data on 

streamflow, water temperature, and channel 

morphology as a basis for river-quality studies. 

Though an admittedly incomplete treatment of 

the subject, the supplement serves to acquaint 

non-technical readers with the utility of hydrologic analysis and the origin of concepts developed in the main discussion. 

Practical applications of the concepts presented 

herein are included in subsequent reports in this 

series on river-quality assessment of the Willamette River basin, Oregon. 

ACKNOWLEDGMENTS 

We wish to acknowledge the aid and encouragement of the Non-Federal Advisory Committee 

on Water Data for Public Use. Our special thanks 

go to the members of the Advisory Committee's 

Ad Hoc Working Group on River Quality Assessment. During the Willamette Study, the group 

included Howard B. Brown, Robert A. Canham, 

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

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

Clarence J. Velz. The inspiration and insights of 

Clarence Velz were particularly helpful. Professor Charles E. Warren of the Department of 

Fisheries and Wildlife, Oregon State University, 

Corvallis, was instrumental in developing the 

uimmediate environment" concept depicted in 

figure 1. 

CRITICAL TEMPORAL AND SPATIAL 

ASPECTS OF RIVER-QUALITY PROBLEMS 

The hydrologic character of a river basin is 

established through the complex interaction of 

~~natural" and manmade features and activities. 

The results of these interactions are manifested 

in the quality of the rivers that drain each basin. 

Thus, every river has a unique hydrologic setting 

which to a large extent controls river-quality 

phenomena both in time and space. Because of 

this control, analysis of a river's hydrology should 

be a prerequisite to selecting an analytical 

method or identifying the data needed to assess 

any river-quality problem. 

There are many hydrologically related factors 

that, depending upon the particular basin, can 

markedly affect river quality. Among these are 

solar radiation, air temperature, evaporation, 

precipitation, runoff, topography, geology, soils, 

vegetation, manmade developments, and landuse activities. Reports on river quality often include consideration of such characteristics. All 

too often, however, this consideration takes the 

form of a perfunctory physiographic description 

or geographic inventory. While interesting in itself, such information provides little insight into 

specific causal relations between hydrology and 

river-quality conditions. Rarely are the dominant 

hydrologic factors identified, understood, and 

adequately quantified to provide a framework for 

quality analysis. 

The dominant hydrologic characteristics of 

rivers related to quality phenomena are streamflow, water temperature, and channel morphology (Velz, 1970). Together, these characteristics 

define the ((immediate environment" of the river 

within which all river-quality processes occur and 

are controlled. (See fig. 1.) A thoughtful awareness and systematic accounting of this ~~immediate environment" is essential to understanding the behavior of river-quality processes and, 

axiomatically, for developing conceptually satisfying explanations about these processes. 

Because streamflow, water temperature, and 

channel morphology are its primary elements, 

a river's Himmediate environment" is in constant flux owing to seasonal and reach-to-reach 

changes in the hydrologic regimen. Over the annual cycle, this flux is so dynamic that it usually 

precludes the adequate definition of the "immediate environment" in a form suitable for detailed cause-effect explanation and quantification 

D2 
EXPLANATION 

IMMEDIATE ENVIRONMENT-Has most direct impact on river quality ; defined largely by streamflow, water temperature, 

and channel morphology. 

GENERATIVE ENVIRONMENT -Most important to river quality during periods of land runoff; incorporates all hydrological 

and terrain properties of the river basin. 

EXTRA ENVIRONMENT- Occasionally impinges on river quality ; includes those factors which originate outside the river 

basin. 

EXTRA ENVIRONMENT 

GENERATIVE ENVIROMENT 

Location 

EXTRA ENVIROMENT 

FIGURE I.-Relation of immediate, generative, and extra environments to river quality. Changes in river quality commonly 

reflect alterations in biochemical processes that result from temporal and spatial changes in surrounding environments. 

of river-quality processes. Therefore, a vital element of river-quality studies is the recognition of 

those seasonal periods when, and reaches where, 

(1) critical problems are most likely to occur and 

(2) hydrologic stability is sufficiently established 

so as to conform with the presumption of system 

equilibrium that underlies most methods of 

river-quality quantification. 

Table 1 summarizes critical temporal and spatial aspects of seven common problems: dissolved-oxygen depletion, excessive algal growth, 

toxicity, salinity, thermal pollution, microbial 

pollution, and sedimentation-turbidity. Each 

problem results primarily from man's use of a 

river, but as indicated, the magnitude, timing, 

and place of occurrence are largely determined by 

the hydrologic controls of streamflow, water 

temperature, and channel morphology. Moreover, 

because of these hydrologic controls, river-quality 

D3 

problems often occur at times and locations far 

removed from their primary causes. 

DISSOLVED-OXYGEN DEPLETION 

During extended low-flow, high-temperature 

periods, the dissolved-oxygen (DO) concentration 

of river water is naturally lower than during 

other periods. This phenomenon relates to the 

fact that the solubility of oxygen in water declines 

with increasing temperature. Low-flow hightemperature conditions also favor long detention 

times, poor mixing, and temperature-induced increases in biological reaction. These factors, when 

coupled with heavy carbonaceous biochemical 

oxygen demand (BOD) loads from municipal and 

industrial wastewaters, can cause severe DO depletion in rivers, particularly in long, sluggish 

pools and tidal reaches. 

During extended dry periods, waste debris from 
TABLE 1.--Selected characteristics of common river-quality problems 

[The magnitude of problems and their temporal and spatial variability are largely controlled by definitive hydrologic characteristicsstreamflow, water temperature, and channel morphology. Brief complementary discussions of each problem are included in the text after 

the table] 

Usual streamflow 

condition 

Likely occurrence 

Primary causative agent(s) Time 

Dissolved-oxygen depletion 

Carbonaceous BOD from munici- Low flow______ Summer, high 

pal and industrial waste-water temperature. 

discharges. 

Place 

Slow-moving pools and tidal reaches. 

Carbonaceous BOD from urban or rural storm-water runoff. 

______ do ________________ do ____________________ Do. 

Nitrogenous oxygen demand ______ do ________________ do _______ _ 

from municipal and industrial 

waste-water discharges. Benthic oxygen demand ________________ do ________________ do _______ _ 

Excessive algal respiration ____________ do ________________ do 

Aquatic plant nutrients from 

municipal, industrial, and 

agricultural waste-water effluents. 

Toxicants from industrial, municipal, and agricultural wastewater discharges; swamp 

drainage. 

Salt-laden agricultural, industrial, and municipal wastewater discharges. 

Excessive algal growth 

Low flow ______ Summer, high 

tern perature. 

Toxicity 

Low flow Summer, high 

temperature. 

Salinity 

Low flow ______ Summer, high 

temperature. 

Shallows or extremely 

slow-moving pools and 

tidal reaches. 

Slow-moving pools and tidal reaches. 

Shallows or extremely 

slow-moving pools and 

tidal reaches. 

Shallows or in euphotic zone of slow-moving 

pools and tidal reaches. 

Slow-moving pools and tidal reaches. 

Lower reaches, especially 

those with very long detention time. 

Naturally saline surface- or ground-water inflow. 

______ do ________________ do _____________________ Do. _________ _ 

Thermal pollution 

Waste-heat discharges _______ _ Low flow ______ Any time, but Any reach below wasteusually summer, heat discharges. 

high temperature. 

Microbial pollution 

Microbes from poorly disinfected 

municipal or industrial waste 

waters; seepage from animal 

feedlots; combined sewer over- flows; urban runoff. 

Any flow Any time __________ Any reach below sources. 

condition. 

Sedimentation and Turbidity 

Accelerated erosion resulting 

from land-use activities. 

High flow _ _ _ _ _ _ Rainy season, 

commonly winter or spring for 

most rivers. 

All reaches, but especially 

those proximate to heavy 

erosional activity. 

human activity and terrestrial plants accumulates in urban areas, rural agricultural land, and 

on other heavily vegetated land. Rainstorms during these periods can wash large quantities of 

oxygen-demanding organic debris into rivers at a 

time when the DO concentration is already low. A 

similar condition can occur downstream of municipalities having combined storm and sanitary 

sewers that overflow to the river during rainstorms. 

Recent studies by Tuffey, Hunter, and Matulewich (197 4) indicate that nitrification (the 

biochemical oxidation of ammonia to nitrite and 

D4 

nitrate by Nitrosomonas and Nitrobacter bac· 

teria) may not be as prevalent in rivers as 

commonly assumed. They found that significant nitrification is almost always restricted to 

(1) shallow ((surface active" reaches with good opportunity for attached growths of nitrifying bacteria or (2) long-detention-time pools, tidal 

reaches, and estuarine bays that have abundant 

suspended matter (also a surface phenomenon). 

Summertime water temperatures (near or greater 

than 20°C) and significant ammonia sources are 

usually required for the nitrification process to 

exert a marked influence on the DO regimen. 
Reduced river velocity during low-flow periods 

allows increased settling and accumulation of 

organic sediments, particularly in depositional 

reaches such as pools and tidal reaches. These 

benthic deposits, usually resulting from the 

settleable-solids fraction of poorly treated municipal and industrial-waste discharges, can exert a 

high BOD duirng summer-high-temperature 

conditions. 

Accelerated algal growth commonly occurs 

below nutrient sources during summer low-flow 

periods. Algal growth can have a marked effect on 

the river DO regimen. Often, large diel variations 

in DO are caused by daytime photosynthesis (DO 

production) and nighttime respiration (DO depletion), particularly in shallows and in the euphotic 

zone (zone of good light penetration) of slowmoving pools and tidal reaches. In addition, pools, 

and tidal reaches are prone to summer benthic 

oxygen demand caused by deposition and decomposition of dead algal cells. 

EXCESSIVE ALGAL GROWTH 

Large inputs of nitrogen, phosphorus, carbon, 

and other nutrients from municipal, industrial, 

and agricultural waste discharges can trigger accelerated algal growth in rivers. Rivers that receive high solar radiation are most prone to such 

eutrophication problems, usually during lowflow, high-temperature summer periods. During 

the colder months, most rivers do not exhibit excessive algal growths. However, during high-flow 

spring and winter periods erosion-transported 

nutrients can accumulate in depositional areas. 

These materials may not be effectively flushed 

before the low-flow season. In such situations the 

nutrients may remobilize and contribute to the 

growth of algae during the warmer, low-flow 

season. 

Given a good supply of nutrients, long slowmoving reaches with high water temperatures 

and solar-radiation levels are the most likely 

places for planktonic (suspended) algal growth. 

Shallow reaches with good light penetration and 

a large streambed area for attached biological activity are optimal places for periphytic (attached) 

algal growth. 

TOXICITY 

Heavy metals, pesticides, and various organic 

and inorganic chemicals can be toxic to the life 

forms found in rivers. Toxic substances may also 

be a public health problem if ingested by humans 

in drinking water or in fish. If the toxic substances are dissolved in the river water, they can 

cause toxicity problems at any time of year and in 

any reach below their entrance into the river. 

However, many toxic substances (particularly 

metals and pesticides) are quite insoluble in river 

water and have an affinity for attachment to sediment. Thus, depositional reaches, as governed by 

the volume and velocity of streamflow and riverchannel characteristics, are most prone to chronic 

(long-term) toxicity problems. Benthic invertebrates, living in intimate contact with toxicantladen sediments or on rocks that are in constant 

contact with toxicants in overflowing water, are 

often the first organisms to exhibit quantifiable 

chronic toxicity. Because of long detention time 

Oonger exposure to toxicants) and high water 

temperature which speed up biochemical processes (higher metabolic rates), summer low-flow 

periods are the most likely times for occurrence of 

toxicity problems. 

Accidental oil spills, "batch dumps" of chemicals, and overflows from swamps are examples 

of situations that can cause acute (immediate) 

toxicity. 

SALINITY 

During low-flow, high-temperature periods, 

river waters naturally tend to become more concentrated with salts because of high evaporation, 

lack of dilution water, and consumptive use of 

water by phreatophytes. Thus, if salty waste waters such as irrigation return flows are discharged 

to the river during low-flow, high-temperature 

periods, high levels of salinity (dissolved solids) 

can result. Although high salinity can occur in 

any reach proximate to a· salty waste-water discharge, the overall tendency is for salinity to increase in a downstream direction. This is because 

salts are conservative substances (that is, they do 

not appreciably degrade or change form with 

time). Highest salinity levels are, thus, commonly 

found in downstream river reaches or in large 

on-river reservoirs. 

Rivers can have high salinity levels owing to 

saline ground-water inflows. If soluble saltbearing sedimentary minerals (carbonate, chloride, sulfate) are prevalent within a basin, the 

river can be naturally quite saline. Ground water, 

which often serves to sustain the low flow (base 

flow) of rivers in the arid southwestern United 

D5 
States, is in contact with these soluble minerals 

for long periods of time in many places. Thus 

many southwestern rivers are saline during 

summer months when flows are low and evaporation rates high. In such rivers, salinity levels may 

not show clear trends of downstream increase or 

decrease and are quickly changed by inflow of 

even small volumes of fresher water from tributaries, springs, or reservoir releases. 

THERMAL POLLUTION 

Thermal pollution can be described as an undesirable superelevation of a river's water temperature and is commonly associated with waste-heat 

discharges of condenser cooling water from 

fossil-fuel or nuclear power plants. Low-flow, 

high-temperature periods are particularly subject 

to thermal problems because fish and other aquatic animals may already be under natural thermal stress. However, in rivers where low-flow 

conditions occur during winter, waste-heat discharges can cause extreme temperature gradients 

or ''thermal blocks" below outfalls. 

Thermal pollution might also be considered in 

the reverse sense-that is, an undesirable depression of water temperature. Depressed water temperature may occur in reaches below thermally 

stratified reservoirs during summertime releases 

of cold bottom waters. 

The water temperature below waste-heat outfalls and reservoirs tends to return to ambient 

levels at a rate governed by air temperature, 

solar radiation, wind velocity, relative humidity, 

and velocity and mixing of the flow. 

MICROBIAL POLLUTION 

All human and animal feces are potential 

sources of pathogenic bacteria and viruses. Because sources of pathogens are numerous and 

widely dispersed in any river basin, microbial pollution is a potential problem at almost any 

streamflow condition, place, or time of year. 

Therefore, the proximity of the source to the river 

and the speed with which microbes can be transported to the river are very important in analyzing microbial pollution problems. Low-flow problems most often result from the direct discharge 

of municipal, industrial, or septic tank wastes, or 

from urban runoff following rainstorms. Highflow problems commonly reflect contaminated 

overland runoff from urban and rural lands (espeD6 

cially animal feedlots) and from hydraulically 

overloaded septic-tank fields. Municipal and industrial waste-treatment plants can also become 

overlt>aded because of sewer infiltration during 

storm periods and discharge large quantities of 

fecal microbes with the untreated sewage. On 

many rivers, the health risks of microbial pollution are greatest during the summer because of 

the increase in water-contact activities. 

SEDIMENTATION AND TURBIDITY 

Runoff from rainfall, particularly large storms 

that follow extended periods of dry weather, can 

transport large quantities of soil particles and organic litter into rivers. Some areas are naturally 

prone to erosion because of inherent physical 

characteristics (for example, steep slopes, poorly 

consolidated soils, lack of vegetal cover). Man's 

land-use activities, primarily those which cause 

widespread removal of vegetal cover and soil disturbance, increase erosion. Once the eroded 

material enters the river it is moved downstream. 

Depending upon the hydraulic regimen, defined 

largely by channel characteristics and the volume 

and velocity of streamflow, transported sediments 

will either stay in suspension, move along the bed 

(bedload), or be deposited in pooled reaches. 

High-flow conditions will cause smaller sized particles to stay in suspension, leading to persistent 

turbidity problems. 

GENERALIZATIONS 

The preceding table and discussion is not a 

comprehensive, in-depth description of riverquality problems. Indeed, a multichaptered treatise would be needed to do justice to this topic. The 

relevance of the table is that it allows recognition 

of several important generalizations that can be 

useful for improving the utility of river-quality 

data programs. 

1. Most river-quality problems related to 

waste-water discharges are manifested during recurring seasonal periods of extended 

low streamflow and high water temperature. 

The problems are commonly most severe in 

slow-moving pooled reaches. 

2. Problems associated with rapid biochemical 

activity (for example, nitrification and diel 

photosynthesis-respiration) occur most 

commonly during periods of extended low 

streamflow and high water temperature in 

shallows having bed material suited for 
abundant biological attachment and growth. 

3. River-quality problems associated with erosion, sediment transport, sediment deposition, and turbidity are common during 

rainy, high-streamflow periods (particularly 

floods). These high-flow problems may also 

lead to biochemically related problems during subsequent low-flow periods, depending 

on the physical character of the river. 

In applying these simple generalizations to 

specific rivers it should always be remembered 

that river developments and alterations such as 

reservoirs, navigation works, dredging, and 

water diversions can cause changes in the natural 

hydrologic regimen. Such changes can drastically 

affect the time and place of occurrence of riverquality problems. Fortunately, the generalizations can still be useful because valid analogies 

can usually be made between a river's natural 

and man-altered hydrology. For example, a reservoir or lock-and-dam navigation channel exhibits many of the same hydrologic phenomena 

(deposition of sediments and long detention time) 

as a deep slow-moving pool. Similarly, man may 

change the natural streamflow pattern of a river 

by water diversion or importation, and by reservoir release or storage. Despite such changes rivers often exhibit distinctive, recurring periods of 

high and low flow somewhat similar to those experienced under natural conditions. 

DISCUSSION 

To experienced hydrologists, limnologists, and 

water-resource engineers, the generalizations 

cited above may seem all too obvious and elementary. It is surprising, therefore, that such seemingly basic concepts have not been more widely 

applied either in the design or in the interpretive 

aspects of river-quality data programs. The reasons for this apparent paradox warrant some 

examination. 

THE "SHOTGUN" APPROACH 

National, State, and regional water-quality 

regulatory agencies have long faced a dilemma. 

On one hand, there is a need for river-quality information from which to develop tactics and 

strategies for water-resource and pollution management. In this case, the general goal is to obtain data suited to trend and cause-effect interpretation. On the other hand, water-quality 

standards dictate a need for data to check compliance with or violation of standards. 

Faced with the dilemma of uwhat kind of data 

to collect?" the tendency has been simply to 

~~shotgun it"-that is, to collect a lot of samples in 

a lot of rivers for a lot of constituents. Apparently, 

part of the rationale for this approach has been 

that once all the data are collected, compiled in 

books, or stored in computer files, ~~users" would 

decide as to their needs and then obtain the data 

for their particular purposes. Without a clear 

definition of goals and information needs, programs have typically become preoccupied with 

long lists oC~pollution sensitive" variables. Seemingly, every year a few new variables are added to 

the list. Sampling frequencies for such programs 

are often selected arbitrarily or based simply on 

convenience. Sampling sites are commonly established by political boundaries, convenience, or 

proximity to a particular ~~polluter." 

Because of the considerable activity generated 

during an era of growing environmental awareness, these large-scale programs have not been a 

popular subject of criticism. Indeed, it can be argued that many positive results have been forthcoming. Sampling methods have been markedly 

improved and standardized. Quality-control measures have been developed and emphasized. 

Data-handling capabilities, particularly computer-processing techniques, have been expanded 

and improved. New sampling and analytical 

hardware has been designed. Perhaps most importantly, the broad scope of environmental, 

economic, and social problems related to river 

quality has been more widely recognized. Despite 

these positive results river-quality data continue 

to be disappointing in terms of their interpretive 

utility, and criticism of data programs has 

mounted in recent years. As indicated in the ~~Introduction," there is a growing number of respected scientists and engineers who feel that 

programs based primarily on the monitoring-type 

approach will never prove efficient for trend or 

causal analysis. If this opinion is correct, and past 

experience indicates strongly that it is, the implications for environmental management can only 

be negative unless a more effective approach is 

developed and implemented. 

AN ALTERNATIVE TO ROUTINE MONITORING 

The basic framework of a new type of largescale river-quality data program is proposed here 

as an alternative to the prevailing approach. 

D7 
Under the proposed program, routine monitoring, 

long the heart of almost all large-scale programs, 

would be reduced in scope and relegated to its 

most useful functions: (1) a means of examining 

compliance with stream and effluent standards; 

(2) a screening device for identifying quality problems; and (3) a complement to in-depth, problemoriented studies. 

The proposed program has three major elements: 

1. A hydrologic analysis focusing on streamflow, 

water temperature, channel morphology, 

and basin history as a precursor to the design of sampling programs or the analysis of 

quality data. 

2. The reinterpretation of existing quality data 

based upon their segregation into comparable temporal and spatial units as derived 

from element 1. 

3. The design of river-quality sampling and 

analysis programs built upon recurrent, 

synoptic studies rather than routine 

monitoring. 

HYDROLOGIC ANALYSIS 

Hydrologic data on streamflow, water temperature, and channel morphology need not be 

exhaustively analyzed to form a basis for segregating and analyzing river-quality data. The fundamental concept is simply to identify the recurring seasonal periods of low and high flow and 

water temperature and to partition the river into 

its distinctive morphologic reaches. 

The basic hydrology of most large rivers in the 

United States can be examined at this level of 

resolution with existing data. Knowledge of seasonal patterns of flow and water temperature can 

be obtained from a simple examination of a 

chronological series of hydrographs and thermographs (see figs. 2 and 5). Topographic or rivernavigation maps are well suited to compiling 

bed-slope profiles and, in conjunction with existing data on channel geometry and bed materials, 

can be used to section the river into distinctive 

reaches (or spatial units) (see fig. 7). 

When conducted in concert with a review of 

river-basin history, the interpretation of hydrologic data allows recognition of major changes in 

the river system wrought by man (such as reservoir flow augmentation, dredging, or channelization). Chronological collations of hydrologic data 

in various tabular and graphical forms are helpful for this purpose (see table 2). Statistical 

analyses of these historical data are invaluable 

for developing predictions such as recurrence 

probabilities for unusually severe low- and highflow events (droughts and floods). These severe 

events often foster critical quality conditions, 

rather than some Haverage" condition, that dictate the design of river-quality management 

strategies and facilities. For this reason, riverquality studies conducted during extreme conditions are particularly relevant for purposes of 

long-range planning. Results from such studies 

can form invaluable prophecies of future riverquality conditions and provide rarely available 

~~end-point data" useful for predictions and comparisons. 

An important aspect of the need for hydrologic 

analysis relates to the valid application of 

mathematics and statistics to the interpretation 

of river-quality data. Most mathematical formulations (even the so-called dynamic models) for 

describing river-quality phenomena are based on 

assumptions of system equilibrium. In the same 

vein, the application of statistics to river-quality 

data analysis is often based upon dubious assumptions of independence of observations and 

randomness of sampling errors. However, we 

have seen in table 1 that it is only within particular seasonal periods and within morphologically 

similar reaches of a river that river-quality 

phenomena can be expected to exhibit the homogeneous or stable ecological conditions that, 

even in the most optimistic sense, are suited to 

such mathematical and statistical assumptions. 

In summary, hydrologic analysis gives the 

river-quality analyst a basic picture of how the 

river system operates in a seasonal and reach-toreach sense, how this system has changed with 

time, and finally, what sort of quantitative 

methods can be realistically applied to make interpretations. Without this basic framework the 

analyst is severely handicapped in trying to interpret quality data because he lacks working 

hypotheses, historical perspective, and valid quantitative methods by which to analyze variations 

inherent in the data. Lacking such essentials, 

analysts in the past have often relied heavily 

on methods involving statistical and computerized manipulations that are incompatible 

with hydrologic reality. In rare cases, where hydrologic data are poor, there may be few alternatives to this approach. However, in most large 

DB 
river basins in the United States where basic 

hydrologic records and historical documentation 

of river-control facilities are available, such arbitrary methods are both unnecessary and unlikely to generate reliable interpretations of 

trends or causal phenomena. 

REINTERPRETATION 

OF EXISTING QUALITY DATA 

As described by Wolman (1971), many existing 

river-quality data have been examined for trends 

and cause-effect relations with disappointing results. We believe that many of these data can still 

be usefully interpreted, provided the data are 

amenable to segregation using river hydrology as 

the segregating tool. 

An important concept in this endeavor is that 

the quality data should be subjected to interpretation by mathematical or statistical means only 

after the segregation step. The previously discussed generalities can be used as an initial 

guide, but the segregation procedure should also 

involve an analysis of antecedent hydrologic conditions, particularly streamflow and watertemperature patterns. Antecedent conditions 

partly determine whether one set of data was collected during a condition when the river's environment was similar enough to permit valid comparisons to be made with another data set. 

For example, consider a set of DO readings obtained at a river station just following the spring 

snowmelt period at a flow of10,000 ft3fs (280 m3/s) 

and a water temperature of 15°C. These data are 

not comparable with DO readings from the same 

station taken in the fall at the end of a sustained 

period of low flow, even if streamflow and water 

temperature conditions were similar to those of 

the spring snowmelt period. In the case of the 

snowmelt period, the river environment is in a 

state of rapid chemical and biological transformation. Dissolved-oxygen readings reflect a confounding set of dynamic ecological interactions 

that exist only during a brief time. In contrast, 

the chemical and biological processes during the 

sustained low-flow period tend to be more nearly 

similar from day-to-day. Data from this period 

are, thus, ideally suited to segregation, analysis, 

and comparison with subsequent data from similar sustained low-flow periods that occurred in 

the past or that will recur in the future. In other 

words, quality data from one year can be made 

comparable to those from another year by normalizing the data using the seasonal stability of 

the river environment as the common denominator. With the data normalized, the impacts of 

man can be examined relatively independently of 

hydrologically induced seasonal variations of inriver processes. 

For high flows, the normalization process is 

often more complex than for low flows because it 

involves an accounting of many antecedent variables and the consideration of the "generative," 

as well as the "immediate" environment (see fig. 

1). These conditions are primarily a function of 

precipitation, extent of vegetal cover, erodibility 

of geologic and soil materials, and land-use patterns. Detailed real-time data for continuous 

quantification of these antecedent conditions is 

seldom available. Even if such data were available, a valid argument could be made for not 

using them all. That is, without a way of synthesizing the data, the analyst would soon be tired 

and confused by the sheer volume of information. 

A practical compromise to this dilemma is first 

to obtain a general knowledge of basin weather 

patterns and terrain properties through field reconnaissance and study of existing climatic records, geologic maps, topographic maps, and interpretive land-resource reports. From such 

know ledge, inferences and hypotheses can be 

drawn as to how the general quality of land runoff 

(and, thus, the quality of the river) might vary, 

both temporally and spatially. From these general inferences and hypotheses, pertinent questions can be formulated and used in the process of 

segregating the high-flow river-quality data. For 

example: Were the data collected before or after 

leaf fall? Was the high flow caused by snowmelt 

or was it solely from rainfall? Was the ground 

saturated prior to the runoff event? Were the data 

collected at the lower end of a long pool that allowed sediment to be deposited before passage by 

the sampling site? How did reservoir operations 

affect the high-flow event and the transport of 

suspended materials? Answers to questions such 

as these can provide both a framework for segregating existing data and essential interpretive 

clues for analyzing trends and causal phenomena 

that had previously been overlooked. 

REPETITIVE SYNOPTIC STUDIES 

We propose that the interpretive core of riverquality data programs should be repetitive synoptic studies rather than routine monitoring. A 

D9 
synoptic study can be described as a river-wide (or 

multireach) study involving coordinated, intensive sampling over a short time period (several 

days to 1 or 2 weeks). Velz (1970, p. 400-421) 

terms these studies ttshort-term intensive stream 

surveys." A detailed discussion of synoptic studies 

is also presented by Kittrell (1969). The underlying rationale and advantages of the snyoptic 

study approach are described in the following discussion. 

For most river-quality variables (or processes), 

synoptic study is the only means by which enough 

concurrent data can be collected within the river 

and its ~'immediate and generative environments" 

to obtain a reflection of the river as an integral, 

continuous system. Even with a well-designed 

study this reflection is imperfect and can be seen 

for only a brief period. However, subsequent 

studies made during similar hydrologic conditions 

allow meaningful comparisons to be made using a 

repetitive series of comparable data. 

Unlike routine monitoring, synoptic studies 

allow sampling to be tailored to fit the needs of 

each particular river. This allows a concentration 

of effort on particular problems of interest, rather 

than the expenditure of effort on the collection of 

a few data on a large number of arbitrarily selected parameters. Also, because synoptic studies 

need be of only short duration, essential corollary 

information (for example, waste-water loading, 

reservoir-operating patterns, and solar-radiation 

conditions) can be obtained and processed with a 

minimum of effort. That is, one does not have to 

keep track of Heverything" all year round. 

Rather than the generation of data as an end in 

itself, problem-oriented synoptic studies foster 

interpretive-type reports. In contrast to compilations of monitor data, such reports contain qualitative descriptions and insights necessary for 

data segregation, causal analysis, and the development of generalizations relevant to all rivers. Thus, interpretive reports tend to develop an 

evolutionary pattern of analysis. This is vital because once gained and incorporated in a report, 

knowledge need not be "rediscovered" every 5 or 

10 years. 

An important, though often overlooked, aspect 

of data programs relates to the morale of the participants. Each of the authors has personally experienced (and sympathetically noted similar 

experiences in others) the dehumanizing, assembly-line feeling inherent with routine 

monitoring. These feelings stand in contrast to 

the feelings of purpose and curiosity that we and 

our coworkers experienced throughout the synoptic studies of the Willamette River, Oregon (Rickert and others, 1976). 

The concept of synoptic studies is anything but 

new. They have been a basic tool of limnological 

and engineering study for many decades. However, they have seldom been employed on therepetitive basis that we propose and believe is required for fruitful analysis of pollution trends and 

cause-effect phenomena on a nationwide basis. 

Viewed from the broadest perspective, then, a 

commitment to a nationwide program of synoptic 

river-quality studies would involve a shift to a 

more flexible, opportunistic approach, and away 

from a rigidly structured routine approach. Many 

different types of studies and interpretive methods would be necessary. Importantly, however, all 

studies would be bound by the common conceptual framework offered by the consideration of 

river hydrology and its intimate relation to each 

river-quality problem. 

For purposes of illustration and discussion it is 

useful to talk in terms of two broad categories of 

river-quality studies. The first is the low-flow, 

high-temperature study, the second is the highflow study. For simplicity these are referred to 

respectively hereafter as drought and flood 

studies. 

DROUGHT STUDIES 

The overriding consideration in the execution 

of the drought study is the attainment of a reasonably stable streamflow and water-temperature regimen prior to and during sampling. A 

useful rule-of-thumb suggested by Velz (1970) is 

that stability should have preceded the study by a 

period roughly equal to the cumulative time-oftravel (at the pr~vailing low flow) of water 

through the reach under study. Often, the attainment of these stable conditions will involve 

waiting it out rather than beginning the study on 

some arbitrary date simply because ~~we had 

everybody ready." In some cases, if stable conditions are repeatedly interrupted by storms or 

other factors, cancellation of surveys or a shifting 

of goals (for example, to examination of stormrunoff loadings) may be in order. 

The most intensive sampling would probably be 

needed in depositional reaches such as elongated 

pools and tidal reaches because these areas comD10 
monly exhibit the most critical quality conditions. However, as implied in table 1, large diel 

variations in river quality are often associated 

with shallow !(surface active" reaches. If these 

diel variations are the primary object of study, 

intensive around-the-clock sampling would be 

needed for short periods. 

As implied above, spatial aspects of synoptic 

sampling design are a difficult subject for generalization, but a particularly relevant comment 

was made by Velz (1970, p. 402-403). 

Ordinarily too many sampling stations are established with 

insufficient number of samples collected at any one. A few well 

selected locations with sufficient number of samples to define 

results in statistical terms provide a much more reliable profile of quality than many stations with only a few samples at 

each. 

Besides the data on river hydrology that form 

the basis for the temporal and spatial design of 

the sampling program, corollary data as derived 

from one or several coordinated substudies will 

usually be needed. For example, a river DO study 

may require substudies to obtain corollary data 

on waste-water BOD loads, benthal deposits, 

periphytic and planktonic algae, nitrogen loads, 

light conditions, and anomalous reaeration 

phenomena related to structures such as lockand-dam navigation works. 

FLOOD STUDIES 

The overriding consideration in the study of 

river quality during flood conditions is a commitment to ''chase" storms and keep reasonable 

records of land-surface conditions just preceding 

and throughout the normal seasonal period of 

high flow. 

Synoptic sampling during floods is a difficult 

task that requires many trained people, tight organization, and good equipment. For these reasons exemplary flood-time river-quality studies 

have been rare in the past. However, increasing 

amounts of quality data are now being collected 

by the Geological Survey (and other agencies) 

during floods as an adjunct to the more routine 

streamflow and suspended sediment measurements. Synoptic quality studies would require 

more effort and better coordination and timing 

with these measurements. 

In some cases, it may be necessary to sample 

bed materials before and after flood events. This 

· is important because the movement and location 

of deposition of sediment-assoicated pollutants, 

rather than their concentration in river water at 

any one time, often controls the timing and magnitude of river-quality problems. 

Remote-sensing data and synthesized, multifactor terrain-element maps are providing new 

tools for analyzing the land-surface conditions 

and erosional processes that control many highflow river-quality problems. The use of these new 

tools in conjunction with synoptic river sampling 

provides the potential to greatly improve the interpretive worth of river-quality data collected 

during flood periods. 

SUMMARY 

1. A host of hydrologically related characteristics 

in each river basin affect river-quality behavior at greater or lesser degrees of importance. However, a perfunctory mention or 

rudimentary inventory of these characteristics adds little to the analysis of riverquality data. 

2. It is probably impossible, and it could be argued unwarranted and unnecessary, to attempt a quantitative accounting of all those 

characteristics of a river basin that impinge 

on river quality. We believe a rational, efficient approach is to concentrate on the 

quantification of those definitive characteristics of river hydrology that exert the 

most direct control on river-quality 

phenomena. These characteristics are 

streamflow, water temperature, and channel 

morphology. 

3. From an analysis of streamflow, water temperature, and channel morphology, it is possible to predict the temporal and spatial 

character of most recognized river-quality 

problems. In other words, because of the 

overriding control exerted by river hydrology on quality, major problems will recur on 

a seasonal basis and tend to be most acute in 

particular types of reaches. 

4. It is only within certain seasonal periods and 

distinctive river reaches that river-quality 

processes approximate (even remotely) the 

relatively stable ecological conditions necessary for the valid application of most of the 

statistics, biochemical equations, and models that are presently available to analyze 

quality data. 

5. Most existing river-quality data have not 

proven useful for interpretive purposes. The 

D11 
existing data lack explanatory power because they are usually derived from routine 

monitoring programs that are poorly suited 

for documenting changes in river quality 

caused by hydrologic phenomena. Thus, the 

data cannot be adequately explained because they do not reflect the ttimmediate environment" that was responsible, in part, for 

the quality characteristics. 

6. On the basis of the points cited above we contend that river-quality sampling and analysis programs can be dramatically improved 

through a deemphasis of the routine 

monitoring approach and added emphasis on 

the following: 

(a) A competent analysis of the natural 

and man-controlled aspects of river 

hydrology as reflected by streamflow 

and water-temperature patterns and 

channel morphology. 

(b) The reanalysis of existing quality 

data, after their segregation into 

compatible temporal and spatial 

units, as derived from the hydrologic 

analysis. 

(c) The use of repetitive synoptic studies 

tailored to the environmental conditions and problems of interest in 

each river basin. 

REFERENCES CITED 

Chow, V. T., 1964, Handbook of applied hydrology: New York, 

McGraw-Hill, 29 chap. 

Deininger, R. A., 1974, Optimization of water quality monitoring programs: Unpub. paper presented at the Internat. 

Symposium on Environmental Quality Monitoring, Division of Environmental Chemistry, Am. Chern. Soc., Los 

Angeles, Calif., April 2-4, 1974. 

Foster, H. A., 1924, Theoretical frequency curves: Am. Soc. 

Civil Eng. Trans., v. 87, p. 142-203. 

Gilroy, E. J., and Steele, T. D., 1972, An analysis of samplefrequency alternatives for fitting a daily stream-temperature model: Proc. Internat. Symposium on Uncertainties 

in Hydrol. And Water Resource Systems, December 1972, 

Tucson, Ariz., p. 592-608. 

Gumbel, E. J., 1941, The return period of flood flows: Jour. 

Ann. Math. Statistics, v. 12, no. 2, p. 163-190. 

Harris, D. D., 1968, Travel rates of water for selected streams 

in the Willamette River basin: U.S. Geol. Survey Hydrol. 

Inv. Atlas HA-273, 2 sheets. 

Howells, D. H., 1971, Land use function in water-quality 

management: Water Resources Bull., v. 7, no. 1, p. 162-

170. 

Interagency Committee on Water Resources, Subcommittee 

on Hydrology, 1966, Methods of flow frequency analysis: 

U.S. Govt. Printing Office, Washington, D.C., 42 p. 

Kilpatrick, F. A., Martens, L.A., and Wilson, J. F., Jr., 1970, 

Measurement of time of travel and dispersion by dye tracing: U.S. Geol. Survey Techniques Water-Resources Inv., 

book 3, chap. A9, 25 p. 

Kittrell, F. W., 1969, A practical guide to water-quality 

studies of streams: U.S. Federal Water Pollution Control 

Adm. Pub. CWR-5, 135 p. 

Kothandaraman, Vecrasomy, and Evans, R. L., 1972, Use of 

air-water relationships for predicting water temperature: 

Illinois State Water Survey Report Inv. 69, 14 p. 

Rantz, S. E., and Eakin, T. E., 1971, A summary of methods 

for the collection and analysis of basic hydrologic data for 

arid regions: U.S. Geol. Survey open-file report, 125 p. 

Rickert, D. A., Hines, W. G., and McKenzie, S. W., 1976, Project development and data programs for assessing the 

quality of the Willamette River, Oregon: U.S. Geol. Survey Circ. 715-C, 31 p. 

Riggs, H. C., 1968, Frequency curves: U.S. Geol. Survey 

Techniques Water-Resources Inv., book 4, chap. A2, 15 p. 

Shearman, J. 0., and Swisshelm, R. V., 1973, Derivation of 

homogeneous streamflow records in the Upper Kentucky 

River basin, southeastern Kentucky: U.S. Geol. Survey 

open-file report, 34 p. 

Tuffey, T. J., Hunter, J. V., and Matulewich, V. A., 1974, 

Zones of nitrification: Water Resources Bull., v. 10, no. 3, 

p. 555-564. 

Velz, C. J., 1970, Applied stream sanitation: New York, John 

Wiley and Sons, Inc., 619 p. 

Willamette Basin Task Force, 1969, Hydrology: The Willamette Basin comprehensive study of water and related 

land resources, app. B, 5 chap. 

Wolman, M. G., 1971, The nation's rivers: Science, v. 174, 

no.4112,p.905-918. 

SUPPLEMENTAL INFORMATION 

QUANTIFICATION OF RIVER HYDROLOGY 

FORQUALITY ANALYSIS 

QUANTIFICATION OF STREAMFLOW 

Many rivers in the United States have stream-gaging records that are ideal for examining seasonal and extreme 

streamflow patterns and their relation to river quality. At 

stations with continually recording stream gages, the temporal variability of streamflow at a particular gaging site is 

uniquely defined by the hydrograph. Concurrently generated 

hydtographs from different gaging stations are useful for 

examining the spatial variability of streamflow. Depending on 

the objective of study, continuous, daily, or monthly hydrographs can be used to examine streamflow patterns. Available 

computer programs interfaced with the Geological Survey's 

surface-water data file, allow machine plotting ofhydrographs 

for any time period for which records exist. (Information about 

the computer data file can be obtained through the Water 

Resources Division, U.S. Geological Survey, Reston, Va., 

22092). 

Figure 2 contains three hydrographs for the Willamette 

D12 
100,000 

1000 

10,000 

100 

1000 

0 

z 0 100,000 0 z u 0 w u (/) 

w a: (/) w a: 0.. 

w 1000 (/) 

0.. w 1- a: w 1- w w u.. ::2: u u co 10,000 co ::::> ::::> u u z z w· w· (.9 

a: 100 (.9 

<( a: J: <( 

u J: (/) u 

0 (/) 

0 

1000 

100,000 

1000 

10,000 

100 

FIGURE 2.-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. 

D13 
~ 0 

(.) 

INDEX MAP OF 

L 

FIGURE 3 . _Willa met t e River basm, · Oregon. 

D14 

20 MILES I 

~0 KILOMETRES 
River at Salem, Oreg. for the water years 1944, 1964, and 

1973. (See fig. 3 for basin map.) The 1944 hydrograph is repreTABLE 2.-Lowest daily discharge for 7, 14, and 30 consecutive 

days in year ending March 31 for Willamette River at Salem, 

Oreg., 1910-701 

Lowest daily discharge in cubic feet per second 

Year 7 days 14 days 30 days 

Period of minor low-flow regulation 

1910 ---------------- 3,750 3,780 

1911 ---------------- 3,750 3,800 

1912 ---------------- 4,570 4,750 

1913 ---------------- 4,240 4,360 

1914 ---------------- 3,510 3,540 

1915 ---------------- 3,420 3,480 

--------------------

1923 ---------------- 3,920 3,980 

1924 ---------------- 2,990 3,070 

1925 ---------------- 3,020 3,070 

1926 ---------------- 3,130 3,140 

1927 ---------------- 3,730 3,730 

1928 ---------------- 3,400 3,500 

1929 ---------------- 3,190 3,190 

1930 ---------------- 2,860 2,860 

1931 ---------------- 2,520 2,580 

1932 ---------------- 3,170 3,170 

1933 ---------------- 3,750 4,020 

1934 ---------------- 2,830 2,860 

1935 ---------------- 3,140 3,220 

1936 ---------------- 3,080 3,090 

1937 ---------------- 3,800 4,000 

1938 ---------------- 3,250 3,270 

1939 ---------------- 2,940 3,060 

1940 ---------------- 2,520 2,520 

1941 ---------------- 3,140 3,210 

1942 ---------------- 2,980 3,160 

1943 ---------------- 4,200 4,300 

1944 ---------------- 2,750 2,830 

1945 ---------------- 3,170 3,300 

1946 ---------------- 3,650 3,770 

1947 ---------------- 3,800 3,940 

1948 ---------------- 4,400 4,670 

1949 ---------------- 3,670 3,730 

1950 ---------------- 4,100 4,260 

1951 ---------------- 4,080 4,200 

1952 ---------------- 3,560 3,750 

Period of major low-flow regulation 

1953 ---------------- 5,320 5,430 

1954 ---------------- 6,160 6,290 

1955 ---------------- 6,160 6,160 

1956 ---------------- 5,950 6,000 

1957 ---------------- 5,380 5,440 

1958 ---------------- 5,680 5,720 

1959 ---------------- 5,410 5,440 

1960 ---------------- 5,510 5,580 

1961 ---------------- 5,780 5,800 

1962 ---------------- 5,740 5,880 

1963 ---------------- 5,490 5,650 

1964 ---------------- 6,470 6,640 

1965 ---------------- 5,360 5,400 

1966 ---------------- 5,030 5,130 

1967 ---------------- 5,340 5,340 

1968 ---------------- 5,840 5,870 

1969 ---------------- 6,940 7,360 

1970 ---------------- 6,610 6,610 

3,850 

4,050 

5,020 

4,840 

3,640 

3,500 

4,210 

3,160 

3,220 

3,190 

3,860 

3,560 

3,240 

2,920 

2,640 

3,170 

4,360 

2,900 

3,350 

3,130 

4,110 

3,410 

3,170 

2,570 

3,390 

3,220 

4,360 

2,880 

3,390 

3,830 

4,310 

4,880 

3,880 

4,610 

4,360 

3,980 

5,770 

6,560 

6,280 

6,150 

5,670 

5,830 

5,460 

5,680 

5,840 

6,090 

5,790 

6,740 

5,460 

5,290 

5,420 

5,950 

7,400 

6,770 

1 For example, the 1930 data are from Apnl 1, 1929. to March 31, 1930. 

sentative of natw-al streamflow patterns while the 1964 and 

1973 hydrographs reflect the impact of reservoir regulation. 

Regulation began on a large scale in 1953 (see table 2). Note 

particularly the recurrent nattrre of the July to September 

low-flow period and the effect that reservoir regulation has 

had on the low-flow regimen. The 1944 hydrograph (preregulation) shows a long recession in flow from April to September while the 1964 and 1973 hydrographs (postregulation) 

exhibit a more abrupt transition into a relatively steady lowflow period. 

Other types of computer programs allow quick, relatively 

inexpensive tabulation and collation of useful streamflow 

characteristics. For example, table 2 summarizes the lowest 

mean daily streamflow values for the Willamette River, Oreg. 

for consecutive 7-, 14-, and 30-day periods for the period 

1910--70. In this tabulation the effect of reservoir regulation • 

depicted in Figw-e 2 becomes more quantifiable. Note, for instance, the marked increase in consecutive 30-day flows that 

have occurred since regulation began in 1953. Prior to 1953 

the annual consecutive 30-day low flow ranged from 2,570 to 

5,020 ft;3/s (72.8-142 m3/s) and averaged 3,670 ft3/s (104 m3is). 

Between 1953 and 1970 the consecutive 30-day low flow 

ranged from 5,290 to 7,400 ft3fs (150--210 m3fs) and averaged 

6,010 ft3Js (170 m3/s). 

LOW FLOWS 

As described above, the quantification of a river's low-flow 

pattern should begin with a visual examination of hydrographs. Ideally, hydrographs from several gaging stations and 

from several years should be available for this purpose. The 

lowermost gaging station on the river is usually the most 

indicative of basinwide low-flow patterns. 

In cases where virtually no streamflow data are available, 

regionalization techniques (Rantz and Eakin, 1971, p. 51) can 

often be effective for defining streamflow patterns. These 

techniques are based upon the transfer of streamflow data 

from gaged basins to nearby, physically similar ungaged basins. Streamflow regionalization can usually provide sufficient 

resolution to depict the general timing, dtrration, and magnitude of low flows, particularly if only general seasonal patterns are needed. 

Depending upon the nature of the streamflow records and 

the river-quality problem in question, more quantitative 

methods of analysis may be warranted. This will likely be true 

in cases concerned with the design of intensive river-quality 

sampling and analysis programs intended to quantify temporal or spatial trends and pollution cause-effect relations. 

Quantitative low-flow analysis will also be needed to develop 

accurate time-of-travel information, to make estimates concerning phenomena such as atmospheric reaeration, and to 

make studies concerned with river-quality models and predictions. 

For predictive analysis, it is useful to account for the magnitude and duration oflow flows on a probability-of-recurrence 

basis. Such accounting permits the extrapolation of river quality observed under one low-flow condition to that which might 

be observed during severe drought conditions. Because many 

river-quality problems are associated with recurring low 

D15 
flows, the validity of these extrapolations can partly determine the success of river-quality planning and management 

decisions. 

Statistical techniques are often applied to streamflow records to estimate the recurrence probabilities of low-flow 

events. Most techniques in common use by the Geological 

Survey and other Federal water resource agencies are based 

on either the "theory of extreme values" originally advanced 

by Gumbel (1941) or the probability theory of Pearson as 

summarized by Foster (1924) and Chow (1964, pp. 8-14 to 

8-16). Velz (1970) has documented the use of Gumbel's theory 

for analysis of"drought flows." The Geological Survey utilizes 

a modification of the Pearson theory, known as the log Pearson Type III technique (Interagency Committee on Water Reso~~c~s, 1966; Riggs, 1968) for analyzing the recurrence probabiltties of both low and high flows. Using historical streamflow data stored on disks and tapes, computer programs are 

available for performing log Pearson or Gumbel probability 

analyses. 

On intensively regulated rivers where regulation patterns 

change drastically from year to year, low flows may not be 

p_redictable from statistical interpretations. For such rivers, 

nver regulation "rules," numerous hydrographs, and computerized data handling techniques are usually needed for 

quantitative analysis. For example, Shearman and Swisshelm 

(1973J have documented a streamflow-simulation model based 

on long-term streamflow data and reservoir-operating rules 

for a multiple reservoir system in the Upper Kentucky River 

basin. 

Velz (1970) has described many of the basic considerations 

and data requirements for formulation of flow-simulation 

models of intensively regulated rivers. On the basis of studies 

in many regulated rivers, Velz analyzed the impacts on 

streamflow of hydroelectric plants, thermal powerplants, 

navigation works, flood-control works, irrigation, and diversions. Importantly, he stressed that the availability of statistical techniques and the computer does not preclude the need for 

thinking and a familiarity with the river in question. 

V) 30 :::> 

U5 

_J 

UJ 

HIGH FLOWS 

As with low flows, the seasonal character of a river's highflow patterns can be examined through visual hydrographic 

analysis. In many basins, 3 or 4 years of streamflow record 

from a strategically located stream gage is sufficient to depict 

the general temporal aspects (timing and duration) of a river's 

high-flow season. Several stream gages and at least 3 or 4 

years of record are needed to examine the spatial variability of 

high-flow patterns. Exceptions to this generalization occur in 

arid Southwestern basins where a distinctive high-flow season 

may not be evident. 

After visual hydrographic analysis of general high-flow patterns, the hydrographs can be of direct use for segregating 

quality data through scrutiny of antecedent runoff conditions 

that existed prior to quality sampling. A series of antecedent 

analyses from several years of record and at several gaging 

stations provides a basis for evaluating temporal and spatial 

river-quality trends. If strong correlation exists between 

streamflow and a particular river-quality variable (for example, turbidity!, more quantitative techniques can be employed 

as a precursor to cause-effect analysis and prediction. Quantitative techniques for predicting the recurrence probabilities 

of high flows, as is the case with low flows, are based largely 

upon statistical manipulation. 

Gumbel's "theory of extreme values" or Pearson's probability curves are the methods by which high-flow recurrence 

probabilities are usually computed. Such statistical analyses 

are referred to as flood-frequency analyses. As is the case with 

drought-frequency analysis, computer programs are available 

for describing the magnitude, duration, and frequency of high 

flows. Computerized analysis of high flows should always be 

accompanied by a study of basin physiography and floodcontrol reservoirs. 

QUANTIFICATION OF WATER TEMPERATURE 

Many investigators, including Gilroy and Steele (1972), 

Velz (1970), and Kothandaraman and Evans (1972), have 

(.) Observed data V) 

UJ 

UJ 

a: 20 <-' 

UJ 

Cl 

~ 

w· 

a: 

:::> 10 

I-

<{ 

a: 

UJ 

c.. 

~ 

UJ 

I- 0 

0 s 

FIGURE 4.--Sine curve for representing river temperature patterns. 

D16 
noted and quantified the correlation between seasonal air- and 

water-temperature patterns. Further, Gilroy and Steele 

(1972) and Kothandaraman and Evans (1972) have proposed 

the use of a harmonic sine function (fig. 4) as an approximate 

model of river water-temperature patterns. For the many rivers that do not have extensive water-temperature data, such 

techniques can be used to derive seasonal water-temperature 

patterns. 

On rivers with several years of water-temperature records, 

seasonal patterns usually can be easily recognized from thermographs; these are simple plots of weekly or monthly average water temperature versus time (see fig. 5). 

If records of water temperature are fairly long (-10 years), 

statistical analysis can be used to establish the probability of 

extremes. Because the health of fish and other important 

aquatic organisms is often dependent upon maintenance of 

specified temperature ranges (rather than mean temperatures), the ability to estimate the probality of extreme temperatures is an important factor for river-quality planning 

and management. 

An example of the use of a graphical statistical analysis of 

water-temperature patterns is shown in figure 6. Note the 

identification of the "period of most severe drought flow." Concurrent examination of overlapping periods of critical streamflow and water-temperature patterns is a great advantage offered by such graphical presentations. 

Many methods exist for the statistical analysis of watertemperature data, and readers desiring more discussion are 

referred to the references cited previously in this report. As is 

the case for streamflow data, the Geological Survey provides 

computerized storage, retrieval, and analytical tools for 

water-temperature data for many rivers in the United States. 

QUANTIFICATION OF CHANNEL MORPHOLOGY 

Data on slope, channel geometry, and bed material are the 

basic information for the quantitative description of the 

reach-to-reach variability of river channels. Perhaps the first 

objective in using these data for river-quality analysis is determination of the location and extent of pools and shallows. 

This objective can often be attained with readily available 

information augmented by some field measurements and observations. 

The slope of a river can be examined with a simple graph of 

channel elevation versus river mile (for example, see fig. 7). 

Approximate slope profiles can be prepared directly from 

existing topographic maps by noting the elevation of contour 

lines which cross the river. 

More precise definition of the slope profile and identification 

of pools and shallows requires channel-geometry measurements (width and depth) taken at various levels of streamflow. 

Such data are often available in the form of maps from the 

North Santiam River 

at Niagara 

Willamette River 

at Salem 

South Yamhill River 

near Willamina 

Maximum 

25 

(I) 

::> 

c;; 

...J 

w 

(.) 20 (I) 

w 

w 

(( 

(.!) 

w 

c 

~ 15 

w' 

(( 

::> 

1-

<( 

(( 10 w 

Q. 

~ 

w 

1-

5 

0 

JFMAMJJASOND JFMAMJJASOND JFMAMJJASON 

FIGURE 5.-Mean monthly and maximum and minimum daily water temperatures for the North Santiam, 

Willamette, and South Yamhill Rivers, Oreg. 

D17 
30 

25 

en 

::::> 

en 

...J 

UJ 

(.) 

20 en 

UJ 

UJ 

0:: 

(.9 

UJ 

0 

z 15 w· 

0:: 

::::> 

1-

<( 

0:: 

UJ 

a.. 10 

~ 

UJ 

1-

Period of 

most severe 

5 drought flow 

I· ·I 

0 

J D 

FIGURE 6.-Seasonal pattern of surface water temperature for Olentangy 

River at Delaware, Ohio. A, most probably monthly mean value;B, oncein-10 year monthly mean value; C, once-in-10 year maximum 3-day average; shaded area, range within which monthly mean can be expected in 80 

percent of years. [Adapted from Velz, 1970, p. 72] 

U.S. Army Corps of Engineers, the U.S. Coast and Geodetic 

Survey, the U.S. Coast Guard, or other agencies responsible 

for river navigation and regulation. In cases where channelgeometry maps do not exist or where channel changes have 

occurred since existing maps were prepared, a recording 

fathometer and boat can be employed to cross-section the rivers quickly and with suitable accuracy. When referenced to 

existing river-stage gages and streamflow data (to account for 

depth and width changes), channel-geometry maps can be 

used to calculate reach-to-reach time of travel on the basis of 

volumetric displacement. For estimating time of travel during 

high-flow conditions and in extremely shallow reaches, dye 

tests are recommended. Discussion relative to time-of-travel 

calculations by the volumetric-displacement technique is 

available in Velz (1970l. Kilpatrick, Martens, and Wilson 

(1970) have documented procedures for calculating time of 

travel from dye tests. 

An example of a time-of-travel graph for the Willamette 

River, Oreg., as computed from channel geometry, river stage, 

and streamflow data, is shown in figure 8. Using such a graph, 

one can identify likely reaches of deposition or scour, calculate 

pollutant residence time from any known outfall location, and 

select sampling sites for optimal description of timedependent river-quality variables such as BOD. 

The characterization of a river's bed materials is best accomplished by field observation and sampling. Several boat 

trips down the river, during which dredge samples, photographs, and visual observations are made, are usually sufficient to characterize the spatial distribution of bed materials. 

The bed materials should be examined for biological growths, 

D18 
(A) 

i 

26.5 mi (43 km) 

2 : 25.5 mi (41 km) 

\-\ 

s 

( 3 135 mi (217 km) 

187 mi (301 km) 

{ 

\ 

0 30 MILES 

I ·, I 

I 

0 50 KM 

(B) 

200~1ir-rilill-1-1-t~-r-r-r-.----- OOL REACH 

METRES 

160 

120 

80 

40 

~r-~---~--~---r-~-~----------------------U-P_S_T_R--EA M __ R_E_A_C_H-----------+~:~~~~~ 

SEAl 100~t-1--t-t-lr-l-t-l--r-t-t-i~r-t-i--r-F~~~~r-r-~-r-.-,--~~~,-~~J SEA LEVEL~~~~~~~~-1~5-0~~~~-L~~~~-1~0-0-L-L-L-L-L~~-J~L-SLO-L-L-L~~-J~~L-L-O~LEVEL 

DISTANCE, IN RIVER MILES ABOVE MOUTH 

300 200 100 0 

DISTANCE, IN RIVER KILOMETRES ABOVE MOUTH 

FIGURE 7.-Willamette River, Oreg., A, Distinctive morphologic reaches. B, Elevation profile. 

color, and odor. Some form of size analyses may be warranted, 

depending on the objective. Care should always be taken to 

consider antecedent conditions, as floods or man-induced activities such as dredging can cause changes in the nature of 

bed materials. 

In some cases, quantitative information on riverbed materials is available through the District Offices of the Geological 

Survey, particularly on rivers that are commonly sampled for 

suspended sediment and bed load. Agencies responsible for 

river navigation and dredging are also potential information 

sources. 

D19 
RIVER KILOMETRES ABOVE MOUTH 

Salem Portland 

0 

30 

20 

EXPLANATION en 

>- Willamette River discharge at <( 

Q Salem, in cubic feet per second 

_j 

w 2600 

> <( 

a: ----4900 1-

LL. 7000 0 

w 

~ 10 ~ 

0 

187 150 100 50 0 

-

__________ ......,,__:Newberg 1. Tidal ...1 Upstream Reach Pool -..-Reach--, 

RIVER MILES ABOVE MOUTH 

FIGURE B.-Cumulative time of travel for various low flows, Willamette River, Oreg. 

D20