A Report of the
Committee on Water Quality Criteria
    Environmental Studies Board
   National Academy of Sciences
  National Academy of Engineering

      Washington, B.C., 1972
          At the request of
           and funded by
The Environmental Protection Agency
      Washington, D.C., 1972

For sale by the Superintendent of Documents, U.S. Government Printing Office,
                  Washington, D.C. 20402 - Price: $12.80.
                        Stock Number 5501-00520

EPA Review Notice

    This report was  prepared under a  contract financed by  the  Environmental
Protection Agency and is approved by the Agency for publication as an important
contribution  to the scientific literature,  but  not as  the Agency's sole criteria for
standards setting purposes. Neither is it necessarily a reflection of the  Agency's views
and policies. The mention of trade names  or commercial products does not constitute
endorsement  or recommendation for their use.

     The study reported herein was undertaken under the aegis of the National Re-
search Council with the express approval of the Governing Board of the NRG. Such
approval indicated  that the Board considered that the problem is of national signifi-
cance, that elucidation or solution of the  problem required scientific or technical
competence, and that the resources of NRG were particularly suitable  to the  conduct
of the project. The  institutional responsibilities of the NRC were then discharged in
the following manner:
     The members of the study committee were selected for their individual scholarly
competence and judgment with due consideration for the balance and breadth of
disciplines. Responsibility for all aspects of this report rests with the study committee,
to whom we express our sincere appreciation.
     Although the reports of our study committees are not submitted for approval to
the Academy membership nor to the Council, each report is reviewed by a second
group of  appropriately qualified individuals according  to procedures established
and  monitored by the Academy's Report Review Committee. Such reviews are in-
tended to determine, among other things, whether the major questions and relevant
points of view have been addressed  and whether the reported findings, conclusions,
and  recommendations arose from the available data and information. Distribution
of the report is approved, by the President, only after satisfactory completion of this
review process.

                                                                July 22,  1972
Environmental Protection Agency
Washington, D.C.

    It is our pleasure to transmit to you the report Water Quality Criteria, 1972 pre-
pared by the National Academy of Sciences-National Academy of Engineering Com-
mittee on Water Quality Criteria.
    This book is the successor to  the Water Quality Criteria Report of the National
Technical Advisory Committee to the Secretary of the Interior in  1968.  The 1972
Report drew significantly on its  1968 predecessor; nevertheless the  current study
represents a complete reexamination of the problems,  and a critical review of all
the data included here.  The conclusions offered reflect the best judgment  of the
Academies' Committee.
    The Report develops scientific criteria arranged in categories of major beneficial
use. We are certain that the information and conclusions contained in this Report
will be of use and value to the large number of people throughout the country who
are concerned with achieving a high level of water quality for the Nation.
    It is our pleasure to  note the substantial personal contributions of the members
of the Committee on Water Quality Criteria and its Panels and advisers. They have
contributed more than 2,000 man-days of effort for which they deserve our  gratitude.
In less than a year and a half, they have collected a vast amount  of scientific and
technical information and presented it in a way that we believe will be most helpful
to Federal and State officials as well as to the scientific community and the public.
Oversight responsibility for the document, of course, rests with the Committee on
Water Quality Criteria ably chaired by Dr. Gerard A. Rohlich of the University of
Texas at Austin.
    We wish also to express our appreciation to the Environmental Protect ion Agency
which, without in any way  attempting to influence the Committee'!:  conclusions,
provided technical expertise  and  information as well as the resources to undertake
the study.
    In the course of their work the Committee and Panels identified  several scientific
and technical areas in which necessary data is insufficient or lacking. The Academies
find that a separate report is urgently required that specifies research needs to  enable
an increasingly effective  evaluation  of water  quality.  We are  currently  preparing
such a report.
       Sincerely yours,
PHILIP HANDLER                                 CLARENCE H. LINDER
President                                         President
National Academy of Sciences                         National Academy of Engineering

                  Environmental Studies Board
National Academy of  Sciences-National Academy of Engineering

           Dr. DAVID M. GATES, Chairman
           Dr. HENDRIK W. BODE
           Dr. REID A. BRYSON
           Dr. ARTHUR D. HASLER
           Dr. THOMAS F.  MALONE
           Dr. ROBERT S.  MORISON
           Dr. ROGER REVELLE
           Dr. JOSEPH L. SAX
           Dr. CHAUNCEY  STARR
           Dr. JOHN  A. SWARTOUT
           Dr. ALEXANDER ZUCKER,  Executive Director


 Dr. GERARD A. ROHLICH, University of Texas, Austin, Chairman
 Dr. ALFRED M. BEETON, University of Wisconsin, Milwaukee
 Dr. BOSTWICK H. KETCHUM, Woods Hole Oceanographic Institution
 Dr. CORNELIUS W. KRUSE, The Johns Hopkins University
 Dr. THURSTON E. LARSON, Illinois State Water Survey
 Dr. EMILIO A. SAVINELLI, Drew Chemical Corporation
 Dr. RAY L. SHIRLEY, University of Florida,  Gainesville
 Dr. CHARLES R. MALONE, Principal Staff Officer
 Mr. CARLOS M. FETTEROLF, Scientific Coordinator
 Mr. ROBERT C.  ROONEY,  Editor

Panel Members
    Dr. CORNELIUS W. KRUSE, The Johns Hopkins University, Chairman
    Dr. MICHAEL CHUBB, Michigan State University
    Mr. MILO A. CHURCHILL, Tennessee Valley Authority
    Mr. NORMAN E. JACKSON, Department of Environmental Services,
      Washington,  D.C.
    Mr. WILLIAM L. KLEIN, Ohio River Valley Water Sanitation Commission
    Dr. P. H. McGAUHEY, University of California, Berkeley
    Dr. ERIC W. MOOD, Yale University
    Mr. RALPH FORCES, Delaware River Basin Commission
    Dr. LESLIE  M. REID, Texas A & M University
    Dr. MICHAEL B. SONNEN, Water Resources Engineers, Inc.
    Mr. ROBERT O. SYLVESTER, University of Washington
    Mr. C. W. THREINEN, Wisconsin Department of Natural Resources
    Dr. RICHARD I. PIETZ, Scientific Secretary

Advisors and Contributors
    Dr. W. N. BARNES, Tennessee Valley Authority
    Mr. A. LEON BATES, Tennessee Valley Authority
    Dr. ERNEST BAY, University of Maryland
    Dr. HARWOOD S. BELDING, University of Pittsburg
    Dr. KENNETH K. CHEW, University of Washington
    Dr. T. F. HALL,  JR., Tennessee Valley Authority
    Dr. A. D. HESS, U.S. Department of Health, Education, and Welfare
    Mr. ROBERT M. HOWES, Tennessee Valley Authority
    Dr. RAY B. KRONE, University of California, Davis
    Mr. DAVID  P. POLLISON, Delaware River Basin Commission
    Dr. R. A. STANLEY, Tennessee Valley Authority
    Dr. EUGENE B. WELCH, University of Washington
    Dr. IRA L. WHITMAN, Ohio Department of Health

EPA Liaisons

Panel Members
    Dr. THURSTON E. LARSON, Illinois State Water Survey, Chairman
    Dr. RUSSELL F. CHRISTMAN, University of Washington
    Mr. PAUL D. HANEY, Black & Veatch, Consulting Engineers
    Mr. ROBERT  C. McWHINNIE,  Board of Water  Commissioners,  Denver,
    Mr. HENRY J. ONGERTH, State Department of Public Health, California
    Dr. RANARD J. PICKERING, U.S. Department of the Interior
    Dr. J. K. G. SILVEY, North Texas State University
    Dr. J. EDWARD SINGLEY, University of Florida, Gainesville
    Dr. RICHARD L. WOODWARD,  Camp Dresser & McKee, Inc.
    Mr. WILLIAM ROBERTSON  IV, Scientific Secretary

Advisors and Contributors
    Dr. SAMUEL D. FAUST, Rutgers  University

EPA Liaisons

Panel Members
    Dr. ALFRED M. BEETON, University of Wisconsin, Chairman
    Dr. JOHN CAIRNS, JR., Virginia Polytechnic Institute and State University
    Dr. CHARLES C. COUTANT, Oak Ridge National Laboratory
    Dr. ROLF HARTUNG, University of Michigan
    Dr. HOWARD E. JOHNSON, Michigan State University
    Dr. RUTH PATRICK, Academy of Natural Sciences of Philadelphia
    Dr- LLOYD L. SMITH, JR.,  University of Minnesota,  St. Paul
    Dr. JOHN B. SPRAGUE, University of Guelph
    Mr. DONALD M. MARTIN, Scientific Secretary

Advisors and Contributors
    Dr. IRA R. ADELMAN,  University of Minnesota, St. Paul
    Mr. YATES M. BARBER, U.S. Department of the Interior
    Dr. F. H. BORMANN, Yale University
    Dr.  KENNETH  L.  DICKSON,  Virginia Polytechnic Institute  and State
    Dr. FRANK M. DTTRI, Michigan State  University
    Dr. TROY DORRIS, Oklahoma State University
    Dr. PETER DOUDOROFF, Oregon State University
    Dr. W. T. EDMONDSON, University of Washington
    Dr. R. F. FOSTER, Battelle Memorial Institute, Pacific  Northwest Laboratory
    Dr. BLAKE GRANT, U.S. Department of the Interior
    Dr. JOHN HOOPES, University of Wisconsin
    Dr. PAUL H. KING, Virginia Polytechnic Institute and State University
    Dr. ROBERT E. LENNON, U.S. Department of the Interior
    Dr. GENE E. LIKENS, Cornell University
    Dr. JOSEPH I. MIHURSKY, University of Maryland
    Mr. MICHAEL E. NEWTON, Michigan  Department of Natural Resources
    Dr. JOHN C. PETERS, U.S. Department of the Interior
    Dr. ANTHONY POLICASTRO,  Argonne National Laboratory
    Dr. DONALD PRITCHARD, The Johns Hopkins University
    Dr. LUIGI PROVAZOLI, Yale University
    Dr. CHARLES RENN, The Johns Hopkins University
    Dr. RICHARD A. SCHOETTGER, U.S. Department of the Interior
    Mr. DEAN L. SHUMWAY, Oregon State University
    Dr. DAVID L.  STALLING, U.S. Department of the Interior
    Dr. RAY WEISS, Scripps Institute of Oceanography

EPA Liaisons

Panel Members
    Dr.  BOSTWICK H.  KETCHUM, Woods Hole Oceanographic Institution,
    Dr. RICHARD T. BARBER, Duke University
    Dr. JAMES CARPENTER, The Johns Hopkins University
    Dr. L. EUGENE CRONIN, University of Maryland
    Dr. HOLGER W. JANNASCH, Woods Hole Oceanographic Institution
    Dr. G. CARLETON RAY, The Johns Hopkins University
    Dr. THEODORE R. RICE, U.S.  Department of Commerce
    Dr. ROBERT W. RISEBROUGH, University of California, Berkeley
    Dr. MICHAEL WALDICHUK, Fisheries Research Board of Canada
    Mr. WILLIAM ROBERTSON IV, Scientific Secretary

Advisors and Contributors
    Mr. CLARENCE CATOE, U.S. Coast Guard
    Dr. GEORGE R. HARVEY, Woods Hole Oceanographic Institution
    Dr. THEODORE G. METCALF, University of New Hampshire
    Dr. VICTOR NOSHKIN, Woods Hole Oceanographic Institution
    Dr. DONALD J. O'CONNOR, Manhattan College
    Dr. JOHN H. RYTHER, Woods Hole Oceanographic Institution
    Dr. ALBERT J. SHERK, University of Maryland
    Dr. RICHARD A. WADE, The Sport  Fishing Institute

EPA Liaisons
    Dr. C. S. HEGRE

Panel Members
    Dr.  RAY L. SHIRLEY,  University  of Florida, Gainesville, Chairman
    Dr. HENRY V. ATHERTON, The University of Vermont
    Dr. R. D. BLACKBURN, U.S. Department of Agriculture
    Dr. PETER A. FRANK, U.S. Department of Agriculture
    Mr. VICTOR L. HAUSER, U.S. Department of Agriculture
    Dr. CHARLES H. HILL, North Carolina State University
    Dr. PHILIP C. KEARNEY, U.S. Department of Agriculture
    Dr. JESSE LUNIN, U.S. Department of Agriculture
    Dr. LEWIS B. NELSON, Tennessee Valley Authority
    Dr. OSCAR E. OLSON, South Dakota State University
    Dr. PARKER F. PRATT, University of California, Riverside
    Dr. G. B. VAN NESS, U.S. Department of Agriculture
    Dr. RICHARD I. PIETZ, Scientific Secretary

Advisors and Contributors

    Dr. L. BOERSMA, Oregon State University
    Dr. ROYCE J. EMERICK, South Dakota State University
    Dr.  HENRY  FISCHBACH, U.S. Department of  Health,  Education, and
    Dr. THOMAS D. HINESLY, University of Illinois
    Dr. CLARENCE LANCE, U.S. Department of Agriculture
    Dr. J. M. LAWRENCE, Auburn University
    Dr. R. A. PACKER,  Iowa State  University
    Dr. IVAN THOMASON, University  of California, Riverside

EPA Liaisons

Panel Members
    Dr. EMILIO A. SAVINELLI, Drew Chemical Corporation, Chairman
    Mr. I. B. DICK, Consulting Chemical Engineer
    Mr. CHARLES C. DINKEL, Drew Chemical Corporation
    Dr.  MAURICE FUERSTENAU, South Dakota School of Mining and
    Mr. ARTHUR W. FYNSK, E. I. du Pont de Nemours & Co., Inc.
    Mr. GEORGE J. HANKS, JR.,  Union Carbide Corporation
    Mr. WILLIAM A. KEILBAUGH, Cochrane Division, Crane Company
    Dr. JAMES C. LAMB, III, University of North Carolina
    Mr. JAMES K. RICE, Cyrus Wm. Rice Division, NUS Corporation
    Mr. J. JAMES ROOSEN, The Detroit Edison Company
    Mr. ROBERT H. STEWART, Hazen and Sawyer
    Dr. SIDNEY SUSSMAN, Olin Corporation
    Mr. CHARLES H. THORBORG, Gulf Degremont Inc.
    Dr. WALTER J. WEBER, JR., The University of Michigan
    Mr. DONALD M. MARTIN, Scientific Secretary

Advisors and Contributors
    Mr. MAXEY BROOKE, Phillips Petroleum Company
    Mr. ROY V. COMEAUX, SR.,  Esso Research and Engineering Company
    Mr. HARRY V. MYERS, JR., The Detroit Edison Company

EPA Liaisons

     In 1971, at the request of the United States Environmental Protection Agency,
the National Academy of Sciences-National Academy of Engineering undertook the
revision  of  WATER QUALITY CRITERIA, the  1968 Report  of the National
Technical Advisory Committee (NTAC) to the Secretary of the Interior. The Acad-
emies appointed a  Committee on Water Quality Criteria and six Panels, and the
responsibility  for overseeing  their activities  was assigned to the  Environmental
Studies Board, a joint body of the Academies.
     The guidelines for the Academies' Committee were similar to those followed by
the NTAC.  The Federal Water Pollution Control Act of 1948, as amended by the
Water Quality Act of 1965, authorized the states and the federal government to
establish water quality standards for  interstate and coastal waters. Paragraph 3,
Section 10 of the 1965 Act reads as follows:
         Standards of quality established pursuant to this subsection shall be
     such as to protect the public health or welfare, enhance the quality of water
     and serve the purposes of this Act. In establishing such standards the Secre-
     tary, the Hearing Board, or the appropriate state authority shall take into
     consideration their use and value for public water supplies, propagation of
     fish  and wildlife, recreational purposes, and  agricultural, industrial, and
     other legitimate uses.
Because of the vast amount of material that falls into the rubric of fish and wildlife,
the Academies established separate Panels  for freshwater and marine aquatic life
and wildlife. Thus the  Committee's six Panels were: (1) Recreation and Aesthetics,
(2) Public Water Supplies, (3) Freshwater  Aquatic Life  and Wildlife, (4) Marine
Aquatic Life and Wildlife,  (5) Agricultural Uses of Water, and (6) Industrial Water
     The members  of the Committee  and its Panels were scientists  and engineers
expert and experienced in the various disciplines associated with the subject of water
quality. The Panels also drew upon special advisors for specific water quality  con-
cerns,  and in  addition were  aided  by  Environmental Protection  Agency experts as
liaison at the  Panel meetings. This arrangement  with EPA facilitated the Panels'
access  to EPA data on water quality. Thirty-nine meetings  were  held by the Com-
mittee and its Panels resulting in an interim report to the Academies and the Environ-
mental Studies Board on December 1, 1971. This was widely circulated, and com-
ments on it were solicited from many quarters. The commentaries were then considered
for inclusion by the Committee and the appropriate Panels.  This volume, submitted
for publication in August  1972, within eighteen  months of the inception of the  task,
is the final version of the Committee's report.
     The 1972 Report is vastly more than a revision of the NTAC Report. To begin
with, it is nearly four times longer. Many new subjects are discussed in detail, among
them:  the recreational impact of boating,  levels  of use, disease vectors, nuisance
organisms, and aquatic vascular plants; viruses in relation to public water supplies;
effects of total dissolved gases on aquatic life; guidelines for toxicological research on
pesticides and uses  of toxicants in fisheries management; disposal of solid wastes in
the ocean; use of waste water for irrigation; and  industrial water treatment processes


and resultant wastes. Many toxic or potentially toxic substances not considered by
the NTAC are discussed including polychlorinated biphenyls, phthalate esters, nitrilo-
triacetate (NTA), numerous metals, and chlorine. The additional length also reflects
the greater current awareness of how various characteristics of water affect its quality
and use; and  the expansion of the information base of the NTAG  Report through
new data from recent research activities and the greater  capabilities of information
processing, storage, and retrieval—especially evident in the three appendixes—have
made their impact on the increase in size. In spite of these additions, however,  the
1972 Report differs from  the NTAC  Report in that its  six Sections do not provide
summaries.  The Committee agreed that an understanding of how  the recommend-
ations should  be interpreted and used can be gained only by a thorough reading of
the rationale and the evaluation of criteria preceding the recommendations.
     Although each Section was prepared  by its appropriate Panel,  some discussions
reflect the joint effort of two or more Panels. These combined discussions attempt to
focus attention where desirable on  such subjects  as  radioactivity,  temperature,
nutrient enrichment, and growths of nuisance organisms. However, the majority of
topics were most effectively treated by individual Panel  discussions, and the reader
is encouraged  to make use of the Tables of Contents and the index in assessing the full
range of the Report's coverage  of the  many complex aspects of water quality.
     Water quality science and its application have expanded  rapidly, but much
work remains to be done. In the course of this revision, the Committee and its Panels
have identified many areas where further knowledge is needed,  and these  findings,
now in  preparation, will be published separately by the National Academy of Sci-
ences-National Academy of Engineering as a report on research  needs.
     Social perspectives and policies for managing, enhancing, and preserving water
resources are undergoing rapid and pervasive change. Because of the stipulations of
the 1965 Water Quality Act, interstate water resources are currently categorized by
use designation, and standards to protect those uses are developed from criteria. It is
in this context that the Report of the NAS-NAE Committee, like that of the NTAC,
was prepared. Concepts of managing water resources are  subject  to social, economic,
and political decisions and will continue to evolve; but the Committee believes that
the criteria and recommendations in this  Report will be of value in the context of
future as well as current approaches that might be taken to preserve and enhance
the quality of the nation's water resources.
                                GERARD A. ROHLICH
                                Chairman, Committee on Water Quality Citeria

    The NAS-NAE Committee on Water Quality Criteria and its Panels are grate-
ful for the assistance of many institutions, groups, and individuals. The Environmental
Studies Board provided guidance throughout all phases of the  project, and the En-
vironmental Protection Agency cooperated in making available their technical and
informational  resources. Many research organizations  and individuals contributed
unpublished data for the Panels' examination and use in the Committee's Report.
    Numerous groups  and individuals  provided  reviews and comments,  among
them several Federal agencies with staff expertise in water quality sciences,  includ-
ing NOAA of the Department of Commerce, the Department of the Interior, the
Department of Health, Education, and  Welfare, the Atomic Energy Commission,
the Department of Agriculture, and the Department of the Army; scientists from the
University of Wisconsin, especially Drs.  Grant Cottam,  G.  Fred Lee, Richard B.
Corey, David Armstrong, Gordon Chesters, Mr. James Kerrigan; and many  others
from academic, government, and private research institutions, including the National
Research Council.
    Much useful information including data and literature references was provided
by the Water  Resources Scientific  Information Center of the  U.S.  Department of
the Interior, the National  Referral Center of the Library of Congress, the Defense
Documentation Center of the U.S. Department of Defense, and the Library of the
National Academy of Sciences-National Academy of Engineering. We are indebted
to James L. Olsen, Jr.  and Marilyn  J. Urion of the  Academies'  Library  and to
Robert R.  Hume, National Academy  of Sciences  Publications Editor, for their
    Thanks are also due the many staff personnel of the Academies who assisted the
project, particularly Linda D. Jones,  Patricia A.  Sheret, Eva H.  Galambos, and
Elizabeth A.  Wilmoth. Mrs. Susan B. Taha was a tireless editorial assistant. The
comprehensive author and subject indexes were prepared  by Mrs. Bev Anne Ross.
    Finally, each Committee and Panel member is indebted to  his home institution
and staff for their generous support of his efforts devoted to the Report of the Com-
mittee  on Water Quality Criteria.

NOTICE	     v
   TRIBUTORS	   viii
PREFACE	    xv

                                       GENERAL  INTRODUCTION

  The past decade has been a period of unprecedented
activity directed to man's concern for the quality of the
environment, but a look at history shows that this concern,
although currently intensified,  is not new. The lessons of
history and the findings of archaeologists provide concrete
evidence that at least three thousand years before the birth
of Christ man was cognizant of the need to dispose of his
wastes and other  refuse if he was to keep his environment
livable.1  For thousands of years the guidelines to quality
of the water resource  apparently were based on the senses
of smell, sight, and taste. Whether or not these organoleptic
observations on the  suitability of water  for  use would
match today's criteria is questionable in light of Reynolds'
reference to "the  old woman in the Fens" who "spoke for
many besides herself when she  asked of the new and  pure
supply: Call ye that water?  For  she  said,  it has neither taste
nor smell"2', or in light of the more recent decision of a  state
supreme  court in  1904, which  took  the position  that it is
"not  necessary to weigh  with tenderness and  care the
testimony of experts ... an ordinary mortal knows whether
water is fit to drink and use."3
   Although the concern  for  water  quality  is not  new,
progress has been made in moving from sensory associations
as a means of control to the application of knowledge and
criteria gained from scientific  advances  in detection and
measurement, and in  a greater understanding of the char-
acteristics of water.  Essentially it has been  the develop-
ments of the past century that have provided  criteria for
and knowledge of  water quality characteristics upon which
we base determinations of its suitability for particular  uses.
   Until recently, relatively few  scientists and engineers had
been engaged in this field. The past decade, however, has
seen a tremendous increase in  the number of workers de-
voted to  the  subject  of  water quality assessment. Con-
currently, an increasing awareness of the public has become
apparent. As Leopold states, "The outstanding discovery
of the twentieth  century  is not  television, or radio,  but
rather the complexity of the land organism"; and he points
out that "by land  is meant all of the things on, over, or in
the earth."4 The  growing  public  awareness  of environ-
mental quality has helped to accelerate activity directed to
the solution of problems relating to water quality.
  Forty centuries before the germ theory of disease had the
support of scientifically conducted experiments, some con-
trol measures to provide safe  water supplies were in use.
Boiling, filtration through charcoal, and the practice of
siphoning off water clarified by sedimentation were among
the early methods  used  to improve water quality.6 The
regard of the Romans for high quality water is well known,
and their civil works in obtaining water by the construction
of aqueducts and the carrying away of waste waters in  the
cloacae or sewers, and in particular the  Cloaca Maxima,
are matters of common  knowledge. The decline of sani-
tation through the Middle  Ages and into the early part ot
the past century brought on the ravages  of pestilence and
the scourges of cholera, typhoid fever and dysentery, which
led to the resurgence of public concern over water quality.
There  were many experiments and suggestions regarding
filtration for purification as early as  the 17th century. They
culminated in design of the first filters for municipal supplies
by Gibbs in Scotland in  1804 and in England in 1829 by
Simpson who is probably most  renowned for his work in
constructing filters  for  the Chelsea Water Company  to
supply water for London from the Thames River.
  The relationship  of water quality to disease was firmly
established by  the  report  on  the  Broad  Street Well  in
London by Sir John Snow in 1849, and in Edwin  Chad-
wick's  report of 1842 "On an  inquiry into the Sanitary
Condition of the Labouring  Population  of Gt.  Britain."6
The greatest part  of Chadwick's  report developed four
major  axioms  that  are still of relevance today. The first
axiom established the cause and effect relationship between
"insanitation, defective drainage, inadequate water supply,
and overcrowded housing" on the one hand, and "disease,
high mortality  rates,  and low expectation  of life" on  the
other.  The second  axiom  discussed the  economic cost of
ill health. The third dealt with the "social cost of squalor,"
and the fourth was concerned with the "inherent inefficiency
of existing legal and administrative machinery."  Chad wick
argued that the "only hope of  sanitary  improvement  lay
in radical administrative departures" which would call for
new institutional arrangements.

2/'Water Quality Criteria, 1972
   It is evident from these few glimpses into the early years
of development of control  that  the  basic  approach, and
justifiably so, was to provide water suitable  for human use.
A century ago the principal aim was to  provide, by bac-
teriological  examination, a  scientific basis on which to
establish water quality practices for protection of the public
health.  Increasingly, however,  we have come to recognize
that a multitude of materials that may occur in water have
adverse effects on beneficial uses other than that for public
water supplies.


  McKee and  Wolf have provided an excellent  historical
background to  the development of water quality standards
and criteria and have summarized the water quality criteria
promulgated by federal, state, and interstate agencies up
to 1963.7 Since then, many federal and state acts have been
passed and modifications made in state administrative  codes
designed to  establish criteria and standards. Of particular
significance  in  this respect was the impact  of the Federal
Water Pollution Control Act of  19488 as  amended by the
Water Quality Act of 1965.9 The latter required  that the
states adopt:

    • water quality criteria applicable to interstate waters;
    • a plan  for the implementation and enforcement of
      the water quality criteria adopted.

  The Act further noted that the criteria and plans would,
upon approval by the federal government, become the
applicable water quality standards. At that time the Fed-
eral  Water  Pollution Control  Administration was in the
Department of Health, Education, and Welfare.  In May
of 1966, the FWPCA was transferred  to the Department of
the Interior,  and  in  April,  1970 it was  renamed The
Federal Water Quality Administration. In December,  1970,
interstate water quality  and  pollution  control  activities
became  the concern  of the  Environmental Protection
  On April 1,  1968, the FWPCA published the report of
the National Technical Advisory Committee to  the Secre-
tary of the  Interior entitled  Water Quality Criteria.10 This
report,  often referred  to  as the "Green  Book,"  contains
recommendations on water quality criteria for various uses.
The present volume is a revision of that  work with the
objective of compiling and  interpreting  the most recent
scientific data in order to establish what is known about
the materials present in water as related to  specific uses.


  Although it  is  recognized that consideration must be
given to the multiple use requirements placed on our water
resources, this  revision has  followed  the  approach of the
1968  report in making recommendations  in certain use
categories. Such  an approach provides a convenient w,
of handling an otherwise unwieldy body of data. Neith
the approach itself nor the sequence in which the uses a
arranged in the Report imply any comment on the relati
importance of each use. Each water use plays its vital re
in the water systems concept discussed above, and politic;
economic,  and social  considerations that vary with h
torical periods and geographic locations have brought pz
ticular water uses to positions of preeminent Lmportanc
In  contemporary terms,  it  is not difficult  to  argue  t
primary importance of each water use considered in tl
Report: the recreational and aesthetic use of the  Natioi
water resources involves 3.7 billion man-days a year;11 o
public water supply systems  prepare 15 billion gallons p
day for the urban population alone ;12 commercial fishermt
harvested   166,430,000 pounds of fish from the  natior
public inland freshwater  bodies in  1969;13 our  marii
waters yield five billion pounds of fish  annually for hum;
use;14 agriculture consumes 123 billion gallons of water p
day in meeting its domestic, livestock, and irrigation needs
and our industries must have 84,000 billion gallons of wat
per year to maintain their operations.16
  Clearly,  the designation of one water use as more vit
than another is as impossible as it is unnecessary.  Furthe
more,  we  must not even restrict our  thinking  to prese
concepts and designated uses. Those concerned with wat
quality must envisage  future uses and values that may 1
assigned to our water  resources and recognize that mar
activities in altering the landscape and utilizing water m;
one day have to be more vigorously controlled.

  In current practice,  where multiple uses are required,
they will be in most situations, our guidelines to action w
be  the more stringent  criteria. Criteria represent  attemj
to quantify water quality in terms of its physical, chemic;
biological,  and  aesthetic characteristics. Those who  a
confronted with the problem of establishing or evaluati
criteria must do  so within the limits of the objective ai
subjective measurements available to them. Obviously, t
quality of water as expressed by  these  measurements is t
product of many  changes. From the moment of its conde
sation in the atmosphere, water accumulates substances,
solution and suspension, from the air,  from contacts as
moves over and  into  the land  resource, from biologic
processes,   and from human  activities. Man affects  t
watershed  as he  alters the landscape by urbanization, 1
agricultural development,  and by discharging municij:
and industrial residues into  the  water  resource. Thus c
matic  conditions, topography, geological formations, ai
human use and  abuse of this vital resource significant
affect the  characteristics of water, so that its quality vari
widely with location and the influencing factors.
  To look ahead again, it should be stressed that if comii
generations expect  to use  future criteria  established 1

                                                                                  General Introduction/3
          Qualities  and  quantities,  based
          on   scientific   determinations,
          which  must  be identified  and
          may have to be controlled.
for specific
  uses in
Recreational and
  Aesthetic Waters
Public Water Supplies
Fresh Waters
Marine Waters
Agricultural Waters
Industrial Water Supplies
          Analytical   methods   (chemist,
          biologist,  engineer, recreational
          specialists & others).
          Deployment of measuring instru-
          ments  to  provide  criteria  and
          information for assessment and
          Definition of acceptable quality
          related to unique local situation
          involving political, economic and
          social factors and including plans
          for  implementation and  ques-
          tions  of water  use  and  manage-
            (The  operation needed  for de-
             tecting and measuring character-
             istics of water.)
             (The chronological and  spatial
             sampling operations needed.)
              FIGURE 1—Conceptual Framework for Developing Standards from Criteria

 4/ Water Quality Criteria, 1972
 aquatic scientists, baseline areas must be preserved in which
 the  scientists can work. Limnologists, oceanographers, and
 freshwater and marine biologists obtain baseline data from
 studies of undisturbed aquatic ecosystems.  Because all the
 basic  information has not yet been extracted from im-
 portant study sites, it is essential that the natural condition
 of these sites prevail.
  The fundamental  point of departure in evaluating cri-
 teria for water quality in this Report is  that the assignment
 of a level of quality is relative to the use man makes of that
 water. To evaluate the quality of water  required for various
 uses, it is essential to know the limits of quality that have a
 detrimental effect on a designated use. As a  corollary, in
 deciding whether or not  water will be  of suitable  quality,
 one  must determine  whether  or not  the introduction into,
 or presence of any material in the resource, interferes with,
 alters, or destroys its intended use. Such decisions  are sub-
ject  to political, social, and economic considerations.

  The distinction between criteria and standards is important,
 and the words  are not interchangeable nor are they syno-
 nyms for such commonly used terms as objectives or goals.
 As a clarification of the distinction that must be recognize d
 and  the  procedural  steps to  be followed  in developing
 standards from criteria, a conceptual framework based on
 the report "Waste Management and Control"  by the Com-
 mittee  on Pollution NAS-NRC17  is presented  in Figure 1.
 In this context, the definition of criteria  as  used in this
 Report is "the scientific data evaluated to derive recommen-
 dations for characteristics of water for specific uses."
  As a first step  in the development of standards it is es-
 sential  to establish scientifically based recommendations for
each assignable water use.  Establishment of recommen-
dations implies access to practical  methods for detecting
and  measuring the specified physical, chemical, biological,
and  aesthetic characteristics.  In some cases, however, less
than satisfactory methods are available, and in other cases,
less than adequate methods or procedures are  used. Moni-
toring  the  essential  characteristics can  be an operation
concurrent with the identification step.  If adequate criteria
for recommendations are available, and  the identification
and  monitoring procedures are  sound, the fundamentals
are available for the establishment of  effective standards.
 It is again at this step that political, social, and economic
factors enter  into the decision-making  process  to establish
  Although the Committee and its Panels recognize that
 water  quality, water quantity, water use, and waste water
 disposal form a complex  system that is further complicated
 by the interchanges  that occur among the land,  air, and
 water  resources, this Report  cannot be so broad in scope:
 its explicit  purpose is to recommend water quality  char-
 acteristics for  designated  uses in light of the  scientific
 information available at this  time. We are aware that in
some areas the scientific information is lacking, inadequal
or possibly conflicting thus precluding the recommendati(
of specific numerical values. The need to refine the recot
mendations and to establish new ones will become increj
ingly important as additional field information and researi
results become available. Realistic standards are depende
on criteria, designated uses, and implementation, as well
identification and monitoring procedures; changes in the
factors may provide a basis for altering the standards.
   Recommendations  are  usually presented,  either as ri
merical values or in narrative form as summaries. In sor
instances in  place of recommendations, conclusions bas<
on the preceding discussion are given. It is important th
each discussion  be studied because  it attempts to ma
clear the basis and logic used in arriving at the particul
recommendation. The Committee wishes to emphasize t
caveat so clearly stated in the introduction  to  the "Gre>
Book."  The  Committee "does not want to be  dogrnati<
in making its recommendations. "They are meant as guid
lines only, to be used in conjunction with a thorough knov
edge of local conditions.1'18

'Klein, Louis (1957) Aspects of water pollution.  Academic Pre
    Inc. New York.
2 Reynolds, Reginald (1946) Cleanliness and godliness. Doubled
    and Company, Inc. Garden City, New York.
3 Malone, F. E. (1960) Legal viewpoint. Journal Americal Water Wo
    Association 52:1180.
4 Leopold, A.  (1953)  Round river. Luna Leopold,  ed. Oxford U
    versity Press. New York.
'Baker, M. N. (1949) The quest ibr  pure water. The American We
    Works Association, New York.
'Flinn, D. W., ed. (1965) Report on the sanitary condition of 1
    laboring population of Great Britain, 1842, by Edwin Chadwi
    Edinburgh at The University Press.
7 McK.ee, J. E. and H. W. Wolf  (1963) Water quality criteria, secc
    edition. State Water Quality Control Board, Sacramento, C.
    fornia. Publication No. 3-A.
8 U.S. Congress. 1948. Federal Water Pollution Control Act, Pul
    Law  845, 62S., June 30, 1948, p. 1155.
9 U.S. Congress. 1965. Water Quality Act, Public Law 89-234, 7<
    October 2, 1965, p. 903.
10 U.S. Department of the Interior. Federal Water Pollution Cont
    Administration  (1968),  Water  quality criteria: report of
    National Technical Advisory Committee to the Secretary of i
    Interior  (Government Printing Office, Washington, D.C.).
11 See page 9 of this Report.
12 U.S. Department of Agriculture, Division of Economic  Resear
13 U.S. Department  of Commerce, National  Oceanic  and Atm
    pheric Administration, Statistics  and Market News Division.
"U.S. Department  of Commerce (1971) Fisheries  of the Unit
    States. (Government Printing Office, Washington, D.C.)
16 U.S. Department of Agriculture, Division of Economic  Resean
16 See page 369 of this Report.
"NAS-NRC Committee on Pollution  (1966) Waste managers
    and control. Publication No. 1400 NAS-NRC, Washington, D.
18 U.S. Department of the Interior, op. cit. p. vii.

                  Section  I—RECREATION AND  AESTHETICS
                                      TABLE  OF CONTENTS
      AND AESTHETICS	      8

      PURPOSES	     11
          Recommendations	     12

  WATER	     13
        The Role of Regulation	     14
        Factors Affecting  Recreational  Carrying
          Capacity	     14
          Conclusion	     14
        Effects on Water Quality	     16
          Recommendation	     17
          Conclusion	     19
        Defining Eutrophication and Nutrients . .     19
        Effects of Eutrophication and Nutrients. .     20
        Determination  of Trophic Conditions	     21
        Summary of  Measurement of Nutrient
          Enrichment	     23
          Recommendations	     23
        Interrelationships With Water Quality. . .     24
        Interrelationships With Other Biota	    25
        Effects on Recreation and Aesthetics	    25
        Control Considerations	    26
          Recommendation	    27
        Extent and Types of Introductions.
        Some Results  of Introductions	
        Introductions  by Official Agencies.
       Aesthetic Considerations	
       Microbiological Considerations	
       Chemical Considerations	
       Microbiological Considerations	
       Temperature Characteristics	
       pH Characteristics	
        Clarity Considerations	
        Chemical Considerations	
        Maintenance of Habitat	
        Variety of Aquatic: Life	
        Bacteriological Quality	

                                      Page                                                Page
  Recommendation	    37    WATERS OF SPECIAL VALUE	    39
Marine Biotoxins	    37      WILD AND SCENIC RIVERS	    39
  Recommendation	    38      WATER BODIES IN  URBAN AREAS	    39
Trace Metals	    38      OTHER WATERS OF SPECIAL VALUE	    40
  Recommendation	    38            Conclusions	    40
Radionuclides	    38  LITERATURE CITED	    41

  This  section considers water quality  in  the  context of
recreation and aesthetics, on the basis of available scientific
data tempered by  experience  and judgment.  In view of
today's  burgeoning population in  the  United States, the
importance of water quality criteria to preserve and enhance
the recreational and aesthetic  values of water resources is
manifest. The problems involved are both great and urgent.
Our urban centers bear the  brunt of the growth of a popu-
lation that needs and demands water-oriented recreational
resources. But those resources,  already overloaded, are de-
graded  or  rendered unfit for recreation by the effects of
man's activities. The quality of water can be assessed and
to some extent controlled, but  the principal cause of water
pollution is what man does on the land.  Water  must be
protected from harmful land-water relationships, and man
must be protected from the consequences of degraded water

  Recreation is an enigma:  nearly everyone participates in
some type  of recreation,  but few are likely to agree on an
acceptable definition of it. Most persons who are  not pro-
fessionally  involved with recreation tend to define it nar-
rowly in terms of their own experiences.  Many feel that
the term implies some form of strenuous physical activity;
to them, aesthetic appreciation and other  leisure activities
that primarily involve the  mind are  not "recreation."
There is also a tendency for some to  include  only those
physical activities that are commonly identified as "recre-
ation" by public or quasi-public recreation agencies.
  Charles E. Doell, an internationally known authority on
park and recreation planning  and administration, defines
recreation as "the refreshment of the mind or body or both
through some means  which is in itself pleasureful." He
states "almost any activity or mental process may be recre-
ation depending  largely upon  the attitude assumed in the
approach to the process itself (Doell 1963)4.* This concept
  * Citations are listed at the end of the Section. They can be located
alphabetically within subtopics or  by their superior numbers which
run consecutively across subtopics for the entire Section.
is supported by many others (Brightbill 196P, Butler 195!
Lehman 19656). If the attitude of the individual concern
is the key to whether or not an activity may be  classed
"recreation,"  it follows thait one man's work may be  a
other man's recreation; and an unwelcome  social duty
one person may  be  a valuable recreational  experience
another. Certain activities may  be either recreational
part of the daily routine depending on the attitude of t
participant. Recreation  is,  therefore, an  elusive conce
that can bear some  relationship  to any of the major co
cerns of living—work and education,  social duty, or bodi
needs. Whether or not an individual's activity falls with
the psychological realm of  recreation depends  upon  \
attitudes, goals, and  life style at a point in time.
  For the purposes of this report a broad view of recreatit
is adopted, and aesthetic appreciation is considered part
recreation. Thus the term "recreation" includes all  typ
of intensive and extensive  pleasurable activities rangii
from  sedentary, purely aesthetic experiences to  strenuo
activities  that  may  involve  a relatively small  aesthei


  The scope and significance of water-related recreation
activities is not well documented quantitatively, but ;
impression of its importance in the lives of Americans  c;
be obtained from such evidence as license registration ai
sales data, user surveys, economic impact studies, and nc
legislation programs  and regulations.
  License Registration and Sales Data  In 1960,
million persons bought  23 million state  fishing licens(
tags,  permits, and stamps. Ten years later more than '.
million licenses, tags,  permits, and stamps  were held I
over 24.5 million purchasers, an increase of about 28  p
cent over 1960  (U.S.  Department of the Interior 1961
197114). In 1970 sportsmen spent an estimated $287.7 m
lion on fishing tackle and equipment on which  they pa
$14 million in federal excise  taxes (Dingle-Johnson  Ac1
They also  added $90.9 million to state treasuries (Slat
1972),7 and in many cases these funds were matched wi
federal funds for use in fisheries improvement programs.

   The number of recreational boats in use increased even
 more substantially. It was estimated that there were almost
 9 million boats of various types in use  during 1970, an
 increase of 9 per cent over  1966. More than $3 billion were
 spent at the retail level on boating equipment, services,
 insurance, fuel, mooring fees and memberships, a 22 per cent
 increase over 1966 (The Boating Industry 1971)1. In 1970, an
 estimated million pairs of water skis were sold,  a 5 per cent
 increase  in  domestic  and export  sales  for that year  (The
 Boating Industry 1971)1.
   Economic Impact Studies  In  fiscal  1969-70, the
 Corps of Engineers spent $27.6 million to develop or expand
 facilities for swimming,  fishing,  boating, and other water-
 oriented activities (Stout personal communication 1971)18. The
 state parks  of the nation, the majority of which are water-
 oriented, spent $125.8 million in 1970 on capital improve-
 ments and  $177 million on operations and maintenance
 (Stout personal communication  1971)18.
   Although public  expenditures for water-oriented recre-
 ational developments are large, expenditures in the private
 and commercial sectors  are of even  greater magnitude. In
 regions of the  country where water bodies are reasonably
 numerous, most seasonal homes are built on or adjacent to
 water.  In  1970, it was  estimated  that 150,000 seasonal
 homes were built at a cost of $1.2 billion (Ragatz  1971)6.
 Some waterfront locations have been extensively developed
 for a variety of public, private, and commercial recreational
 purposes. The lakes and lake frontage properties  of the
 Tennessee Valley Authority alone were-estimated to contain
 water-based recreational equipment and facilities worth $77
 million and land-based facilities and improvements valued
 at $ 178 million  in  1968 (Churchill personal communication
   Expenditures for other goods and services associated with
 water-oriented recreation are also a major  factor in the
 economy. Boaters,  fishermen,  campers,  picnickers,  and
 others spend considerable sums on transportation, accommo-
 dations, and supplies. For example, preliminary data show
 that some 2.9 million waterfowl hunters spent an estimated
 $245 million during 25 million recreation days in 1970
 (Slater personal communication 1971)17.  The Tennessee Valley
 Authority estimated in 1967 that sports fishermen using its
 reservoirs spent some $42 million in order to  harvest 7,000
 to 10,000 tons offish (Stroud and Martin  1968)8.
   User Surveys   Since World War II,  per capita par-
 ticipation in most  types of recreational activities has in-
creased even more rapidly than the preceding data indicate.
Attendance  at  National  Park Service areas rose from  133
million visits in 1966 to 172 million in 1970, an increase of
 29 per cent. In the same period, visits to Corps of Engineers
reservoirs increased  42 per  cent  to a total  of 276 million.
 Comparable figures for the national forests were  151 million
 in 1966, rising  14 per cent to 173 million in 1970 (Bureau
of Outdoor  Recreation personal communication 1971)16. Most
of the recreation opportunities at Corps of Engineers areas
 and a good proportion of those available on  Park Service
 lands  and  in  national  forests  are  water-based or water-
 related.  Similar growth rates and a predominance of water-
 related  recreational experiences characterize the use  of
 recreational lands managed by the Bureau of Sport Fisheries
 and Wildlife, the Bureau of Land Management, the Bureau
 of Reclamation, and the Department of Defense.
   The preeminent role of water resources in recreation was
 emphasized by the  President's Outdoor Recreation  Re-
 sources  Review  Commission  in  1960.  Extensive  surveys
 showed  that most people seeking outdoor  recreation (90
 per  cent of all Americans) sought it  in association  with
 water, as indicated by the preliminary figures in Table 1-1,
 a  study  made as  part  of the  1970 U.S.  Census  (Slater
 1972)17.  Although it is  impossible  to  estimate what pro-
 portion  of  the use reported by the survey was  actually
 associated with water for those activities that are not water-
 based  but  are often water-related, the  data  nevertheless
 emphasize the magnitude of current participation in water-
 oriented recreation.
   If no  more than half the time spent on  the frequently
 water-related activities was in fact  associated  with water,
 the total man days for water-based and  water-related ac-
 tivities in 1970 would be at least 3.7 billion man  days.
   Participation in water-based and water-oriented recre-
 ation is  likely  to increase in the forseeable  future.  The
 Bureau of Outdoor Recreation (1967)13  predicts that by the
 year 2000 summertime participation in swimming will in-
 crease over  the year 1965 by 207 per cent, in fishing 78 per
 cent, in  boating 215 per cent, in waterskiing 363  percent,
 and in such water-related activities as camping, picnicking,
 and sightseeing 238, 127, and 156 per cent respectively.
   Legislation,  Regulations,  and   Programs  The
 importance of water-based and  water-related recreation to
society is reflected in the  increase  in  legislation and  the
number  of regulations and programs intended to increase
  TABLE 1-1—Participation in Water-Oriented Recreation
                    Activities in 1970
Swimming. .
Total man days
Frequently water related
Pi tracking 	
Camping . 	
Nature walks
Wildlife photography . . .
Total man days

Percent of U.S. population


. . 21
.... 12

Billions of man days


'i. 00

 * For many activities, double counting will occur. (Slater 1972)7

10/Section I—Recreation and Aesthetics
or protect opportunities for these activities. One example
is the Wild  and Scenic Rivers Act  U.S. Congress 1968)9
that authorized a national program to preserve free-flowing
rivers of  exceptional natural or recreational value.  The
Federal Power Commission has required the submission of
recreation and fish and wildlife development plans as inte-
gral parts of hydroelectric license applications. The Federal
Water Project Recreation Act  (U.S. Congress  1965)10 en-
courages state and local participation in planning, financing,
and administering  recreational features of federal water
development projects.  The Estuary  Protection Act (U.S.
Congress  1968)11  authorizes cooperative  federal-state-local
cost sharing and management programs for estuaries, and
requires that federal agencies consult with the Secretary
of the Interior on all land and water development projects
with impacts on  estuaries before submitting proposals to
Congress for authorization.
  The Soil Conservation Service of the U.S. Department of
Agriculture  assists in the development of ponds that often
are used for recreational purposes and watering livestock.
Federal assistance for waterfront restoration and the preser-
vation of environmental values is available under the urban
renewal, open space, and urban beautification programs of
the Department of Housing and Urban Development, the
Land and Water Conservation Fund program of the Bureau
of Outdoor  Recreation, and the historic preservation  pro-
gram of the  National Park Service.


  Although  there  have been instances of  rapid water
quality  deterioration with drastic effects on  recreation,
typically the effect is  a slow,  insidious  process.  Changes
have  come about incrementally as forests are cut, lam
cultivated, urban areas expanded, and industries developec
But the cumulative effect and the losses in recreation oppoi
tunities caused by degraded water quality in this countr
in the past 100 years have been great. In many urban areas
opportunities  for virtually every type of water-based  ac
tivity have been either  severely curtailed  or eliminated
The  resource-based recreation frontier  is  being forcei
further  into  the  hinterland,  Aesthetic values of aquati
vistas are eliminated or depreciated by enchroachment c
residential, commercial,  industrial, military,  or  transpor
tation  facilities.  Drainage  of swamps  to  control  insec
vectors of disease and channelization to control floods hav
a profound effect on water run-off characteristics. A loss ii
water quality and downstream  aquatic environments ani
recreational opportunities is often the price paid for sue!
  The application of adequate local, state, and nationa
water quality criteria is only a partial solution to our wate
quality problems. A comprehensive national land use polk
program with effective methods of decision-making, imple
mentation, and enforcement is also needed.


  Throughout this report the recommendations given ar
to be applied in the context of local conditions. This cavea
cannot be over  emphasized, because variabilities are en
countered in different parts of the country.  Specific  loca
recommendations can be developed now  in many instance
and more will be developed as  experience grows. Numerics
criteria pertaining to other  beneficial water uses togethe
with the recommendations  for  recreational and aestheti
uses provide guidance for water quality management.

  Aesthetics is  classically defined as the branch of philos-
ophy that provides a theory of the beautiful. In this Section
attention  will  be  focused  on the  aesthetics of  water in
natural and  man-made environments  and  the extent to
which  the beauty of that water can be preserved or en-
hanced by the  establishment of water quality recommen-
  Although perceptions of many forms of beauty are pro-
foundly subjective and experienced differently by each indi-
vidual,  there is an apparent  sameness in the  human re-
sponse to the beauties of water. Aesthetically pleasing waters
add to  the quality of human experience. Water may be
pleasant to look upon, to walk or rest beside, or simply to
contemplate. It may enhance the visual scene wherever it
appears, in cities or in the wilderness. It may enhance values
of adjoining properties, public or private. It may provide a
focal point of pride in the community. The perception of
beauty  and  ugliness cannot  be  strictly defined.  Either
natural or man-made visual effects may add  or detract,
depending on many  variables such as distance  from the
observer or the composition and texture of the surroundings.
As one writer has said when comparing recreational values
with aesthetics,  "Of probably greater value is the relaxation
and mental well-being achieved  by viewing and absorbing
the scenic grandeur  of  the great and restless  Missouri.
Many people crowd the 'high-line' drives along the bluffs
to view this mighty river and achieve a certain restfulness
from the proximity of nature" (Forges et al. 1952)19.
  Similarly, aesthetic experience can be enhanced or de-
stroyed by space relationships. Power  boats on a two-acre
lake  are likely  to be more hazardous  than fun, and the
water will be so choppy and turbid that people will hardly
enjoy swimming near the shore.  On  the other hand, a
sailboat on Lake Michigan can be  viewed with  pleasure.
If a designated scenic area is  surrounded by a wire fence,
the naturalness is obviously tainted. If animals can only be
viewed in restricted pens,  the enjoyment is likely  to be less
than if they could be seen moving at will in their natural


  The management of water for  aesthetic purposes must be
planned and executed in the context of the uses of the land,
the shoreline,  and the water surfaces.  People must be the
ultimate consideration. Aesthetic values relate to accessi-
bility,  perspective,  space, human  expectations,  and the
opportunity to derive a pleasurable reaction from the senses.
  Congress  has affirmed and reaffirmed its determination
to enhance water quality in a series of actions strengthening
the federal role in water pollution control and federal sup-
port for water pollution control programs of state and local
governments and industry. In a number of states, political
leaders and  voters have  supported programs to protect or
even restore water  quality  with aesthetics as one of the
  The recognition, identification,  and protection of the
aesthetic qualities  of  water should  be an  objective of all
water quality management  programs. The  retention of
suitable, aesthetic quality is more likely  to be  achieved
through  strict control  of discharges at the source  than by
excessive dependence  on assimilation by receiving waters.
Paradoxically, the values that aesthetically pleasing water
provide are most urgently needed where pollution problems
are most serious as  in  the urban areas and particularly in
the central portions of cities where population and industry
are likely to be heavily concentrated
  Unfortunately, one  of the greatest unknowns is the value
of aesthetics to people. No workable formula incorporating
a valid benefit-to-cost ratio has yet been devised to reflect
tangible  and  intangible benefits accruing  to conflicting
uses or misuses and the cost of providing or avoiding them.
This dilemma could be circumvented by boldly stating that
aesthetic values are worth the cost of achieving them. The
present public reaction to water quality might well support
this position, but efforts in this area have not yet proceeded
far enough  to produce values worthy  of wide acceptance.
(See Appendix I.)


  All surface  waters should be aesthetically pleasing. But
natural conditions vary widely, and because  of this a  series
of  descriptive rather  than numerical  recommendations is
made. The descriptions are intended to provide, in general
terms, for the protection of surface  waters from substances
or conditions arising from other  than  natural sources that

12/Section I—Recreation and Aesthetics
might degrade or tend to degrade the aesthetic quality of
the water.  Substances  or conditions arising from natural
sources may affect water quality independently of human
activities. Human activities that augment degradation from
natural  sources,  such as accelerated erosion from surface
disturbances, are not considered natural. The  recommen-
dations are also  intended to cover degradation from "dis-
charges  or waste," a phrase embracing undesirable  inputs
from all sources attributable to human  activities whether
surface flows, point discharges, or subsurface drainages.
  The recommendations that follow are essentially finite
criteria. The absence of visible debris, oil, scum, and other
matter resulting from human activity is a strict requirement
for aesthetic acceptability. Similarly, recommended  values
for objectionable color, odor, taste, and turbidity, although
less precise, must  be measured as no significant  increase
over background. Characteristics such as excessive nutrients
and temperature elevations that  encourage objectionable
abundance of organisms, e.g., a bloom of blue-green algae
resulting from discharge of a  waste with a high  nutrient
content and an elevated temperature, must be  considered.
  These recommendations  become finite when applied as
intended in the context of natural background conditions.
Specific numbers would add little to the usefulness  of the
descriptive recommendations because of the varying  acute-
ness of sensory perception and because of the variability o
substances  and conditions  so  largely dependent  on loca
  The phrase "virtually free" of an objectionable constituen
as used in the recommendations  implies the concept  c
freedom from the undesirable effects of the constituent bu
not necessarily freedom  from the constituent itself. Thi
recognizes  the practical impossibility of complete absenc
and the inevitability of the  presence of potential pollutant
to some degree.


  Surface waters will be aesthetically pleasing i
they  are virtually free  of  substances  attributabl
to discharges or waste as; follows:

• materials that will settle to form objectionabt
• floating debris, oil, scum, and other matter;
• substances producing objectionable color, odoi
  taste, or turbidity;
• substances  and  conditions   or   combination
  thereof in concentrations  which produce un
  desirable  aquatic  life.

  The many factors  that  influence the recreational and
aesthetic value of water may be broadly grouped  in two
imprecise and overlapping but useful categories: physical
and biological. Physical factors include geography, manage-
ment and land use practices, and carrying capacity. Bio-
logical factors involve the effects of nuisance organisms and
eutrophication, the role  of aquatic plants, species diversity,
and  the  introduction of exotic  species. In making water
quality recommendations that will maintain recreational
and  aesthetic  values  of surface  waters, it  is necessary  to
understand the interrelationships between these factors and
water  quality.  The discussions in this Section emphasize
those interrelationships,  but additional useful detail  can  be
found  in other Sections of this Report,  i.e., Public Water
Supplies (II), Marine Aquatic Life and Wildlife (IV), and
Agriculture (V). Cross references direct the reader to other
sources at appropriate points  in this Section.
  Physical  Factors  Recommendations  applicable  to
water-related environmental  goals may well  define those
constraints that must be imposed on man's land-based ac-
tivities and  upon his physical contact  with water  if the
quality of water  is to be maintained at a level  suited  to
recreational use.  This is especially true  of  aesthetic enjoy-
ment of water, because pleasurable aesthetic experiences
are related to water in its environmental setting and to its
changing appearance caused by  wind, light, and other
natural phenomena.
  Man-made impoundments have provided numerous op-
portunities for recreation that have not existed before, but
their operation in some instances presents a paradox for
recreational users. Often such reservoirs are located on the
upper reaches  of rivers where the natural setting  is itself
conducive to aesthetic recreational enjoyment; but because
they are  often multipurpose projects, their  operation for
water  supply,  seasonal provision of flood storage, daily
provision of hydroelectric  power,  or even  seasonal  fluctu-
ation for mosquito control will change the water  surface
elevation, leave barren  banks exposed, or cause noticeable
or transient disruptions of the otherwise natural appearing
setting. Where the  impoundment specifically provides a
public water  supply, concerned  water  works personnel,
fearing degradation of the quality of the water stored for
this purpose, may impose limitations on the scope of recre-
ational  opportunities.  Thus, the full potential  for recre-
ational  and aesthetic uses of water may well  be curtailed
somewhat  by the  operational  schedule  of a  water body
needed for other purposes, even if the quality of the stored
water meets the stipulated water quality criteria.
  Control  of turbidity  represents  another environment-
related problem, one that must  often be dealt with in terms
of somewhat subjective  local considerations.  Recommen-
dations for turbidity limits are best expressed as percentage
increases over natural background conditions. The waste-
water treatment processes normally employed are intended
to control suspended  particles and associated  problems.
Steps can also be taken to minimize erosion of soil disturbed
by  agriculture,  construction, logging, and other human
activities. Turbidity  from urban and rural areas can  be
reduced  by  ponding or other sedimentation facilities.
Wherever possible, spoils from dredging of navigable waters
should be disposed of on land  or at water sites in such a
way that environmental damage is minimized. If necessary
dredging for new construction  or channel  maintenance  is
performed with caution,  it will  not have  adverse effects on
water quality. (Effects of physical manipulation of the en-
vironment are discussed further  in Section III  on Fresh-
water Aqua ic Life and Wildlife.)
  Biological Factors  Two  principal  types of biological
factors  influence the recreational and  aesthetic value  of
surface waters: those that endanger the health or physical
comfort of people and animals,  and those that render water
aesthetically  objectionable  or  unusable  as a  result of  its
overfertilization. The former include vector and nuisance
organisms; the latter,  aquatic growths of microscopic and
macroscopic  plants.
  The discussion turns next to the physical  factors of recre-
ational  carrying capacity  and sediment  and  suspended
materials, and then to the biological factors.


  In both artificial  impoundments and  natural bodies of
water the physical, chemical, and biological characteristics
of the water itself are not the only factors influencing water-

1 ^/Section I—Recreation and Aesthetics
oriented recreation. Depreciation of the recreational value
of water caused by high levels of use is a growing problem
that can be solved only by management techniques that:
either create more extensive facilities or limit the types and
amounts of use to predetermined desirable levels or carrying
  The recreational resource carrying capacity concept is
not new.  Recreation land managers have  used carrying
capacity standards for decades, but such standards have
generally  been developed  intuitively rather than experi-
mentally.  Dana  (1957)24 called for empirical research in
this field to provide better guidelines for management of
recreation resources. The National Recreation and  Parks
Association reported  in 1969 that almost no research of this
type had  been completed  and  that standards for water-
oriented recreational activities then in use exhibited  a  dis-
turbingly  wide range  of values (Chubb  1969)21.  Among
investigations of the  carrying  capacity of water for  recre-
ational  boating currently being made  are  those at North
Carolina State University  and Michigan State University
(Ashton and Chubb 1971).20 A comparative study of the
canoeing and trout fishing  capacity of four rivers is taking
place in Michigan (Colburn, personal communication 1971)27.
Lucas (1964)25 reported on an on-going recreational carry-
ing, capacity study of the Boundary Waters Canoe  Area.
   Until a number of  these investigations  are completed,
the true nature  and  complexity of the factors involved in
recreational carrying capacity will not be known. However,
in the case of many water-oriented activities it is apparent
that social,  psychological,  and economic  factors are in-
volved,  as well as the physical characteristics of the water
body (Chubb and Ashton 1969)22. For example, boaters on
heavily  used lakes in Southeast Michigan represent a broad
spectrum  of behavioral patterns and attitudes. Fishermen
generally  dislike high-density use and are particularly an-
noyed by speeding boats that create waves. They believe
such activities disturb the fish. Waterfront home and cottage
owners  abhor the noise and litter  generated by  owners of
transient boats on trailers.  On the other hand, many water
skiers enjoy relatively  crowded conditions because  of the
social aspects of the experience; and some cruiser and pon-
toon boat owners enjoy viewing the skiers from their boats.
Thus the boating carrying  capacity of these waters involves
the relative  proportions of the various kinds of uses taking
place and the life  styles,  recreational goals,  and  social
aspirations of the boaters. Carrying capacity becomes a
function of  the levels of satisfaction achieved by  the par-
ticipants (Ashton and Chubb  1971).20
   Screw  propellers  of powerboats  operating  in  shallow
waters create currents that often suspend sediments. Power-
boats can also produce wake waves that cause shore erosion
and result in  water  turbulence. Marl-bottomed lakes and
silty, relatively narrow rivers are especially susceptible to
prolonged turbidity generated by such  disturbances. In
many cases, bank erosion has  been so severe that speed
limitations and wake-wave:  restrictions have  had  to 1
  The size and configuration of a water body influence
recreational use and carrying capacity. Large lakes with
low ratio of shoreline-to-surface area tend to be under-usi
in the middle; conversely, lakes with a high ratio of shor
line-to-surface area tend to sustain more recreational u
per acre.

The Role of Regulation
  Rapid increases  in recreational use  have necessitati
regulations to protect the quality of  the experiences o
tained by  limiting use  so that  carrying capacity  is n
exceeded. Examples are boat speed regulations, limitatio
on horsepower, number of boat launching sites, number
parking places, and zoning and time limitations on wat
skiing and high-speed boating. Motorized crafts are oft<
prohibited.  Michigan is planning to  use  data from
current series of boating carrying capacity  studies to «
tablish  new  criteria  for its  boating  access  site progra
(Ashton and Chubb 1971).20
  The Michigan Department of Natural Resources (1970]
has proposed rationing recreation on  stretches  of  the /
Sable, Manistee,  Pine,  and  Pere Marquette Rivers 1
means of a canoe permit system to reduce conflicts betwe<
canoeists and trout fishermen. The proposed regulatio
would limit the release of Ccinoes to a specified number p
day for designated stretches of these rivers. Other regulatio
are intended to promote safety and reduce trespass, riv
bank damage, vandalism, and littering.  The National Pa
Service has limited annual user days for river running <
the Colorado through the Grand Canyon (Cowgill 1971).2

Factors Affecting Recreational Carrying Capacity
  The carrying capacity of a body of water for recreation
not a readily identifiable finite number. It is a range
values from  which society can select the most acceptafc
limits as the  controlling variables change.
  The schematic diagram (Fig. 1-1) provides an impressi(
of the number of relationships involved in a typical wat
body recreation system.  Recreational carrying capacity
water is basically dependent upon water quality but al
related to many other variables  as shown in the modi
At the  threshold level a relatively small decline in wat
quality may have a considerable  effect on the system ai
result in a substantial decline in the annual yield of wate
oriented recreational opportunities at the sites affected.

   No specific recommendation is made concernir
recreational carrying capacity. Agencies establisl
ing carrying  capacities  should  be aware of  tl
complex relationships of the interacting variabli
and of the constant need to review local establish*
values in  light of prevailing conditions.  Carryir

                                    Factors Influencing the Recreational and Aesthetic Value of Water/15

               (broken box line indicates high probability of change)
                           WATERBODY RESOURCES
                            quantity, type, accessibility
                                                                       WATER QUALITY
                                                                     chemical, physical, and
                                                                     biological characteristics
                                                                                  I  Human   \
                                                                                  I Activities  i
                                                                                  L_       _,
                                  Water Quality



               Cultural Factors     I
              recreation behavior,   I
            ownership, access, and  '
                  Regulations       '
                            REGIONAL SUPPLY OF
                            ALTERNATIVE WATER
                              "Normal"patterns of
                             use for "n" waterbodies
                            Changing Patterns of Use:
                          relationship to supply-demand,
                              socio-economics, and
                                  water quality
                                 Excessive Use:
                           reduced water quality and
                               recreational value
                                Reduced Carrying
FIGURE 1-1—Relationships Involved in a Water Resource Recreation System

 16/'Section I—Recreation and Aesthetics
capacity was discussed in  this Section to call at-
tention to its potential effects on water quality for
recreational use.

  Weathering  of the  land surface and  the  transport  of
particles such as sand,  silt and clay by water, wind, and ice
are natural processes  of geologic  erosion that largely de-
termine  the  characteristics of  our land,  rivers,  estuaries,
and lakes. Man, however, can drastically  alter the amount
of material suspended in  surface  waters by accelerating
surface erosion through various land use and management
practices. Sources of these sediments and suspended ma-
terials such as erosion, mining, agriculture, and construction
areas  are discussed in  Section IV  on Marine Aquatic Life
and Wildlife. In addition to causing siltation problems and
affecting biological productivity, sediments  and suspended
materials affect  the quality  of surface  waters used  for
recreational and aesthetic enjoyment.

Effects on Water Quality
  The importance  of suspended particle  composition and
concentrations  to  the  recreational and aesthetic value  of
surface  water relates  to  its effects on  the clarity,  light
penetration,  temperature, and dissolved constituents  of
surface  water, the  adsorption of toxic materials,  and the
composition, distribution,  and  rate  of sedimentation  of
materials. These  in turn not only affect  recreational and
aesthetic values directly, but they control or limit biological
productivity and  the aquatic life the waters  will sustain  for
enjoyment by people (Buck 1956,28 Cairns 1968).29 Although
the qualitative effects of  suspended particles on  surface
waters are well  recognized, quantitative knowledge and
understanding are limited. (Biological  effects are discussed
in Sections III and IV on Freshwater and Marine Aquatic
  Appearance  The  appearance of water is  relative  to
the perspective  of the viewer and his  expectations.  For
example, the surfaces  of lakes,  streams,  or  oceans viewed
from  shore  appear less turbid than they do  viewed from
above or during immersion. The responses of people viewing
the spectacularly  clear waters  of  Lake  Tahoe or Crater
Lake  are almost  surely aesthetic  in nature, and  allowing
the clarity of such waters to decrease would  certainly lower
their  aesthetic appeal. On  the other  hand, the  roaring
reaches and  the  placid stretches  of the muddy Colorado
River and miles  of the muddy Mississippi  afford another
kind  of aesthetic  pleasure and recreation  which many also
appreciate.  People seem  to  adapt to and  accept a wide
range of water turbidities as long as changes in turbidity
are part of natural processes.  However,  increases in tur-
bidity of water due to man's disturbance of the land surface,
discharge of wastes, or modification of the water-body bed
are subjectively  regarded by  many people  as  pollution,
and so in fact or in fancy they reduce aesthetic enjoyment.
  Light Penetration   The presence of suspended soli
materials in natural waters limits the penetration  by sui
light. An example of the adverse effects of reduced availab
light is  the inability of some fish to see their natural foe
or even the sport fisherman's lure (note the discussion i
Section III,  Freshwater  Aquatic Life  and Wildlife,  pj
126-129). In turbid, nutrient-rich waters, such as an est\
ary or lake where lack of light penetration limits algal repn
duction, a water management  project that reduced sed
ment input to the water  body could conceivably result i
increases of algal production to the nuisance level.
  Temperature  When suspended particles  inhibit  tl
penetration  of water  by sunlight,  greater  absorption i
solar energy occurs near the surface and warms the  wate
there. With its density thus decreased,  the water  colum
stabilizes, and vertical mixing is inhibited. Lower  oxyge
transfer from air to water  also results from higher  watt
surface  temperature. Together with inhibited vertical mi)
ing, this reduces the downward rate of oxygen transfe
especially in still or slowly moving water. In combinatio
with  the oxygen demand of benthic accumulations, an
reduction in downward transfer of oxygen hastens  the d(
velopment of anaerobic  conditions at the bed of  shallo'
eutrophic ponds, and the result may be a loss of aestheti
  Adsorption of Materials   Clay minerals have irregi
lar, platy shapes and large  surface areas with electrostati
charges. As a  consequence,  clay  minerals sorb  cation
anions,  and  organic  compounds. Pesticides  and heav
metals likewise sorb on suspended clay particles, and thos
that are strongly held are carried with the particles  to the
eventual resting place.
  Microorganisms  are frequently  sorbed  on  particular
material and incorporated into bottom sediments when tl"
material settles.  Rising storm waters may resuspend  tr
deposited material,  thereby restoring the microorganisn
to  the  water column. Swimming or  wading could  st
bottom sediments containing bacteria,  thereby effecting
rise in  bacterial counts  in  the water  (Van  Donsel an
Geldreich 1971)33.
  The capacity of minerals to hold dissolved toxic materia
is different for each material and type of clay. The  sorptiv
phenomenon effectively lends a large assimilative capacit
to muddy waters. A reduction in suspended mineral solic
in surface waters can, therefore, cause  an increase in tli
concentrations  of dissolved toxic materials contributed  b
existing waste  discharges (see Section III on  Freshwate
Aquatic Life).
  Beach Zone Effects   When typical river waters cor
taining dispersed clay minerals mix with ocean water i
estuaries to the extent of one part or more of ocean water t
33  parts river water,  the dispersed clay and silt particlt
become cohesive, and aggregates are  formed under  th
prevailing hydraulic conditions (Krone 1962).30 Such aggr«
gates of material brought downstream by storms  eithe

                                                      Factors Influencing the Recreational and Aesthetic Value of Water/17
settle in the estuary, particularly in large shallow bays, or
are carried directly to sea where they often are distributed
over large areas of the sea floor. Those that settle in shallow
bays  can be  constantly resuspended  by wind-generated
waves and held in suspension by waves while tidal currents
circulate the waters throughout  the estuary and  carry a
portion of the  suspended material out to sea.  Suspended
clay mineral particles are weakly cohesive in river waters
having  either unusually  low dissolved salt concentrations
or high proportions of multivalent cations in the dissolved
salts.  When such rivers enter lakes and impoundments, the
fine particles aggregate and settle to the  bed to form soft,
fluffy deposits.
  On lakes,  the natural wind waves maintain beaches and
sandy littoral zones when  there is sufficient fetch. Wind-
driven movement  of the water through  wave action and
subsequent oscillation provides the minimum  velocity of
0.5 feet per second to sort out the fine particles of mineral
soils and organic  micelles and allow them to settle in the
depths.  Wave action extends  to depths of approximately
one-half of the wave length to sort bottom sediments. This
depth is on the order of 5 feet (1.5 m) for a one-mile (1.6
km)  fetch.  When  the  waters are deep enough to allow
settling, fine  sediments which are suspended  drop down
over the wave terrace leaving sorted sand behind. In shallow
water bodies where the orbital velocity of the water particles
of wave action is great enough to lift fine sediments, waters
may  be  kept  in  a state of turbidity  (Shephard  1963).31
Waters without adequate wind-wave action and circulation
do not have  appreciable sorting; and thereforeIsoft bottom
materials, undesirable at facilities like swimming beaches,
may build  up  in  the  shallows. These conditions reduce
clarity and  not only  affect the aesthetic value but also
present  a hazard in swimming.
  The natural phenomenon of  beach maintenance, sup-
plying sand  to beaches and littoral zones, is dependent in
part upon having ample sources of sand such as those pro-
vided by river transport  and shore erosion. Impoundment
of rivers causes sand to settle behind dams and removes it
as a future source for beach maintenance.  Man's protection
of shorelines from erosion also interrupts the supply of sand.
In the erosion process, sand is commonly moved along the
shore in response  to the net positive direction of the wind-
wave forces, or it is carried into deep water to be deposited
on the edge of wave terraces. The location of man-made
structures can,  therefore, influence the quality of beaches.
Piers and jetties can intercept the lateral movement of sand
and  leave impoverished  rocky or hardpan shores on the
up-current  side. Such  conditions are common along the
shores of the large Great Lakes and many coastal waters
(U.S. Army, Coastal Engineering Research Center  1966).w
  Sediment-Aquatic  Plant  Relationships  When
the sediment load exceeds  the transport capacity of the
river, deposition results. The accumulation of sediments in
reservoirs and  distribution  systems has  been a problem
 since ancient times. The deposited materials may so alter
 the original bed materials of surface waters that rooted
 aquatic  vascular plants are  able  to  grow in the newly
 available substrate, thus changing the aquatic environment.
 Fine sediments are often rich in the nutrients required for
 plant growths; and once the sediments are stabilized with
 a few plants, extensive colonization may follow.  (See  the
 discussion of Aquatic Vascular Plants in this Section.)

   Clear waters are normally preferred for  recre-
 ation. Because sediment-laden water reduces water
 clarity, inhibits the growth  of  plants, displaces
 water volume as sediments settle, and contributes
 to the  fouling of  the bottom, prevention  of un-
 natural quantities of suspended  sediments or de-
 posit of sediments is desirable.  Individual  waters
 vary in the natural amounts of suspended sedi-
 ments they carry; therefore,  no  fixed recommen-
 dation can be made.  Management decisions should
 be developed with reference to historical base line
 data concerning the individual body of  water.


   The  impact of both aquatic  vectors  of  diseases  and
 nuisance organisms on water-related recreational  and aes-
 thetic pursuits varies from  the creation of minor nuisances
 to the closing of large recreational  areas (Mackenthun and
 Ingram  1967).58 Organisms of concern  are  discussed  by
 Mackenthun (1969).67
   Massive  emergences  of  non-biting  midges,  phantom
 midges, caddisflies, and mayflies cause serious  nuisances in
 shoreline communities,  impeding  road traffic, river navi-
 gation,  commercial  enterprises and recreational  pursuits
 (Burks  1953,40 Fremling 1960a,46  1960b;47 Hunt  and Bis-
 choff I960;54  Provost 195860). Human respiratory allergic
 reactions to aquatic insect bites have been recognized  for
 many years. They were reviewed by Henson (1966),49 who
 reported the major causative groups to be the caddisflies,
 mayflies, and  midges.
   Among common diseases transmitted by aquatic inverte-
 brates are encephalitis, malaria,  and schistosomiasis,  in-
 cluding swimmers' itch.  The principal water-related arthro-
 pod-borne viral disease of importance to  public health in
 the United States is encephalitis, transmitted by mosquitoes
 (Hess and Holden  1958).61 Many polluted urban streams
 are ideally suited to production of large numbers  of Culex
Jatigans,  a vector of  St.  Louis encephalitis in urban areas.
 Although running waters  ordinarily  are  not suitable  for
 mosquito breeding,  puddles in drying stream beds and
 floodplains are excellent breeding sites for this and other
 species  of  Culex. If such pools contain  polluted waters,
 organic materials present may serve as an increased food
 supply that will  stimulate production (Hess  1956,5* U.S.

IB/Section I—Recreation and Aesthetics
Department  of the  Interior, FWPCA  1967).65  Aquatic
plants also provide breeding sites for some mosquitoes and
other nuisance insects. This relationship  is discussed else-
where in this Section (p. 25).
  Other than mosquitoes, perhaps the most common nui-
sance insects associated with standing freshwater are chir-
onomid midges. These insects neither bite nor carry disease,
but their dense swarms  can interfere with man's comfort
and activities. Nuisance populations have occurred in pro-
ductive natural lakes where the larvae thrive in the largely
organic bottom sediments  (Provost  1958,60 Hunt  and Bis-
choff I960,64 Hilsenhoff 1959).52 In poorly designed sewage
lagoons mosquitoes  and midges may  thrive  (Beadle  and
Harmstrom 1958,38 Kimerle and Enns  1968).66 Reservoirs
receiving inadequately  treated  municipal wastes are po-
tential sources for abundant mosquito and midge production
(U.S.  Department of the Interior,  FWPCA 1967).K In-
creased midge production may be associated with  deterior-
ation in water quality, but this is not always the case. For
example, excessive production can occur in primary sewage
oxidation ponds as well  as in reservoirs (Grodhaus 1963,48
Bay  196436); and in sequential oxidation pond treatment,
maximum midge production may sometimes occur in those
ponds furthest from  the plant effluent where water quality
is highest (Bay et al. 1965).36
  Abrupt changes in water quality such as dilution of sea-
water by freshwater, especially if accompanied by organic
loading, can precipitate extraordinarily high midge pro-
duction  (Jamnback  1954).55 Sudden  decline  in oxygen
supply in organically overloaded ponds  or drying lakes can
disrupt or destroy established  faunal  communities, thus
favoring midge larvae  because they are  tolerant to low
dissolved oxygen  and are  primarily detrital feeders (Bay
unpublished data).67
  The physical characteristics of certain water bodies,  as
much as their water quality characteristics, may sometimes
determine midge productivity  (Bay et  al.  1966).37  For
example, freshly filled  reservoirs are  quickly sedimented
with  allocthanous detritus and  airborne organic matter
that provide food for invading  midge larvae.  The rate of
sedimentation can depend on watershed characteristics and
basin percolation rate or, in the case of airborne sediment,
on the surrounding topography. Predators in these  new
environments are few, and initial midge larval survival is
high. Thomas  (1970)64 has also  reported on the  potential
of newly or periodically flooded areas to produce  large
populations of midges and  mosquitoes.
  Midge production in  permanent bodies of water is ex-
tremely  variable. Attempts have been made (Hilsenhoff'
and  Narf 1968,53 Florida State Board of Health unpublished
datam) to correlate  factors of water quality  with midge
productivity in neighboring lakes and in lakes with certain
identifiable characteristics, but the results have been incon-
  Organism response in organically polluted flowing wate
was  discussed  and  illustrated  by Bartsch  and  Ingran
(1959).34 As water quality and bottom materials change ii
streams recovering from  organic  waste  discharges, largi
numbers of midges and other nuisance organisms may b
produced in select reaches.
  Though blackfly  larvae  are common  in  unpollutec
streams,  an increase  in  suspended organic  food particle
may stimulate increased populations, and abnormally larg<
numbers of larvae have been found downstream from botl
municipal  and industrial waste discharges (U.S.  Depart
ment of the Interior,  FWPCA 1967).65 The larvae feed 01
drifting organic material, and either municipal, agricultural
or certain  industrial  wastes can provide the base for  ai
increased food supply. Bacteria  from soils and sewage ma'
be important in outbreaks of blackflies (Fredeen 1964).45
  Toxic  wastes  can also  affect situations where nuisano
organisms  are found  in increased  numbers. The mos
obvious  mechanism is the  destruction  of more sensitiv
predators and  competitors, leaving the  food supply an<
space available for the more tolerant forms. Surber (1959)6
found  increased  numbers of a tolerant  midge,  Cncotopu
bicinctus,  in waters  polluted  with chromium.  Rotenon
treatment  of  waters  has resulted  in temporary  massiv
increases in blackfly  and midge populations (Cook  an<
Moore 1969).41  Increased numbers of midge larvae wer
found  in a stream reach six months after a  gasoline  spil
(Bugbee  and Walter  1972).6S The  reasons for this are  no
clear but may be linked to the  more ready invasion of ai
area by  these  highly  mobile insects as compared to  les
mobile competitors and predators.
  Persons involved in water-based  activities in many area
of the  world  are subject to  bilharziasis (schistosomiasis),
debilitating and  sometimes deadly disease (World  Healt
Organization  1959).66 This  is not a problem in the cont
nental United States and Hawaii because of the absence c
a vector snail, but schistosomiasis occurs in Puerto Ric
due  to the discharge of human  feces containing Schistosom
eggs into waters harboring vector snails, the most importar
species being Biomphalaria glabrata. B. glabrata can surviv
in a wide range of water quality,  including  facultativ
sewage lagoons;  and people are exposed through conta<
with shallow water near the infected snails. Cercariae she
by the snail  penetrate the  skin of humans  and enter th
   Of local concern  in water-contact  recreation  in  th
United States is  schistosome dermatitis, or swimmers'  itc
(Cort  1928,42 Mackenthun and Ingram 1967,58 Fettero
et al.  1970).44 A number  of schistosome cercariae, noi
specific for humans, are  able to enter the outer layers <
human skin. The reaction causes itching, and the severil
is related  to  the person's  sensitivity and  prior exposut
history (Oliver 1949).59 The most important of the derm;
titis-producing cercariae are duck parasites (Trichobilharzia

                                                       Factors Influencing the Recreational and Aesthetic Value of Water/19
 Snails serving as intermediate hosts include Lymnaea, Physa,
 and Gyraulus (Cort 1950).43 Although swimmers' itch has
 wide distribution, in the United States  it is  principally
 endemic to the north central lake region.  Occasional  inci-
 dence is reported in marine waters (Stunkard and Hinchliflfe
  About 90 per cent of severe swimmers' itch outbreaks are
 associated with Cercaria stagnicolae shed from varieties of the
 snail Lymnaea emarginata.  This relationship is promoted by
 (1)  clean, sandy beaches  ideal for swimming and preferred
 by  the snail; (2) peak populations of the snail host  that
 develop in sandy-bottomed lakes of glacial origin; (3) the
 greatest development  of adult  snails  that  do  not die off
 until toward  the  end  of the  bathing  season; and (4)  the
 cycle of cercarial  infection so  timed that the greatest num-
 bers of cercariae emerge during the  hot weather in  the
 middle of the summer when the greatest amount of bathing
 is done (Brackett  1941).89 Infected vector snails are  also
found  throughout the United  States  in swamps, muddy
 ponds, and ditches; but  dermatitis rarely results, because
 humans seldom use these areas without protective clothing.
  In some marine recreational waters jellyfish or sea nettles
 are  serious problems. Some species possess  stinging mecha-
 nisms whose cnidoblast filaments can penetrate human skin
 causing painful,  inflammed  weals. The effects of water
 quality on their abundance is not known, but Schultz and
 Cargo  (1971)61  reported that  the summer  sea nettle,
 Chrysaora quinquecirrha, has been  a problem in Chesapeake
Bay since colonial days. When these nettles are abundant,
 swimming is  practically  eliminated and fishermen's  nets
 and traps are clogged.

  The role of water quality in either limiting or
augmenting the production of vector and nuisance
 organisms involves many interrelationships which
 are not clearly  understood.  Since organic wastes
 generally directly  or indirectly  increase  biomass
 production,  there  may be  an attendant  increase
 in  vector  or nuisance organisms.  Some wastes
 favor  their  production by  creating water  quality
 or  habitat  conditions that limit  their  predators
and competitors. Increased  production of vector
 and nuisance organisms may degrade a healthy
 and  desirable  human environment and  be  ac-
 companied  by a lessening of recreational and aes-
 thetic values (see  the discussion of  Aquatic Life
 and Wildlife in this Section, p. 35.)


  Man's recent concern with eutrophy relates primarily to
 lakes, reservoirs, rivers, estuaries,  and coastal  waters  that
 have been or are being over-fertilized through society's
carelessness to a point where beneficial uses are impaired
or threatened.  With  increasing urbanization, industriali-
zation, artificial soil fertilization, and soil mantle disruption,
eutrophication has become a serious problem affecting the
aesthetic and recreational enjoyment of many of the nation's

Defining Eutrophication and Nutrients
  Lakes have  been  classified  in  accordance with their
trophic  level or  bathymetry  as eutrophic,  oligotrophic,
mesotrophic, or dystrophic (National Academy of Sciences
1969,97  Russell-Hunter  1970,106 Warren 1971,114 Stewart
and Rohlich 1967).107 A typical eutrophic lake has  a high
surface-to-volume ratio,  and an abundance of nutrients
producing heavy growth of aquatic plants and other vege-
tation; it contains highly organic sediments, and may have
seasonal or continuous low dissolved-oxygen concentrations
in its deeper waters. A typical oligotrophic lake has a low
surface-to-volume ratio, a nutrient content that  supports
only a low level of aquatic productivity, a  high dissolved-
oxygen  concentration extending to the deep waters,  and
sediments largely inorganic in composition.  The character-
istics of mesotrophic lakes lie  between those  of eutrophic
and oligotrophic lakes. A dystrophic lake has waters brown-
ish from humic materials, a relatively low  pH, a reduced
rate of bacterial decomposition, bottom sediments usually
composed of partially decomposed  vegetation,  and  low
aquatic  biomass productivity.  Dystrophication is a lake-
aging process different from that of eutrophication. Whereas
the senescent stage in eutrophication may be a productive
marsh or swamp, dystrophication leads to a peat  bog rich
in humic materials but low in productivity.
  Eutrophication refers to  the addition of  nutrients to
bodies of water and to the effects of  those nutrients.  The
theory that there is a natural, gradual, and  steady increase
in external nutrient supply throughout the existence  of a
lake is widely held,  but there is no support for this idea of
natural  eutrophication (Beeton and Edmondson 1972).74
The paleolimnological literature supports instead a concept
of trophic equilibrium such as that introduced by Hutchin-
son (1969).91 According  to this  concept the progressive
changes that occur  as a lake ages  constitute an ecological
succession effected in part  by the change in the shape of the
basin brought about by its filling. As the basin fills and the
volume  decreases,  the resulting shallowness increases  the
cycling  of  available  nutrients  and this  usually increases
plant production.
  There are many naturally eutrophic lakes of such recre-
ational value that extensive efforts  have been made to con-
trol their overproduction  of nuisance aquatic plants and
algae. In the past,  man  has often accepted  as a natural
phenomenon the loss or  decreased value of a  resource
through eutrophication. He has drained shallow, senescent
lakes for agricultural purposes or filled them to form building

20/'Section I—Recreation and Aesthetics
sites. The increasing value of lakes for recreation, however,
will reorder man's priorities, and instead of accepting such
alternative uses of lakes,  he  will  divert  his reclamation
efforts to salvaging and renovating their recreational values.
  Artificial or cultural eutrophication results from increased
nutrient supplies through  human activity. Many aquatic
systems have  suffered cultural eutrophication in the past
50 years as a consequence of continually increasing nutrient
loading from the wastes  of society.  Man-induced nutrients
come largely from the discharge of municipal and industrial
wastewaters and from the land runoff effects of agricultural
practices and  disruption of the soil mantle  and its vege-
tative  cover in the course of land  development and con-
struction.  If eutrophication is not to become  the future
major  deterrent to the recreational and aesthetic  enjoyment
of water, it is essential that unnatural additions of nutrients
be kept out of water  bodies through improved wastewater
treatment and land management.

Effects of Eutrophication and Nutrients
  Green Lake, a lowland lake with high recreation use in
Seattle, is an example of a natural eutrophic lake (Sylvester
and Anderson I960),109 formed some 25,000 years ago after
the  retreat  of the Vashon glacier.  During the ensuing
years,  about  two-thirds  of the  original  lake volume was
filled with inorganic and organic sediments.  A core taken
near the center of the lake  to a sediment depth of 20.5 feet
represented a  sediment accumulation over a  period of ap-
proximately 6,700 years. Organic, nutrient, and chlorophyll
analyses on samples  from the  different  sediment  depths
indicated a relatively constant rate of sedimentation, sug-
gesting that Green Lake has been in  a natural state of
eutrophy for several thousands of years.
  The recreational and aesthetic potential of the lake was
reduced for most users by littoral and emergent  vegetation
and by heavy blooms of blue-green algae in late summer.
The aquatic weeds provided harborage  for production of
mosquitoes and interfered with boating, swimming, fishing,
access  to the beach, and  model boat activities. The heavy,
blue-green algal blooms  adhered to swimmers.  The wind
blew the algal masses onto the shore where they decomposed
with a  disagreeable odor.  They dried like a blue-green paint
on objects along the shoreline, rendered boating and fishing
unattractive, and accentuated water line marks on boats.
  Nevertheless, through  the continuous addition of low-
nutrient dilution water  by the City of Seattle (Oglesby
1969),98 Green lake has been reclaimed through a reversal
of the  trophic development to mesotrophic and is now
recreationally  and aesthetically acceptable.
  Lake Washington is an example  of a large, deep, oligo-
trophic-mesotrophic lake that  turned eutrophic in  about
35  years, primarily through the discharge of treated and
untreated domestic sewage. Even to laymen, the change
was rapid, dramatic, and  spectacular. In the period of a
year, the apparent color of the lake water turned  from
bluish-green to rust as a result of massive growths of th<
blue-green alga, Oscillatoria rubescens. This threat to aesthetii
and recreational enjoyment  was a key factor in voter ap
proval of Metro, a metropolitan sewer district. Metro ha,
greatly reduced the nutrient  content of the lake and conse
quent algal growth by diverting wastewater discharges ou
of the drainage basin (Edmondson 1969,82 1970).83
  Lake Sammamish at the northern inlet  of Lake Wash
ington appeared to be  responding to the enrichment i
received  from  treated sewage and other nutrient waste
although  it had  not yet produced nuisance conditions tc
the extent found in Lake Washington (Edmondson 1970).8
However, subsequent diversion of that waste by Metro hai
resulted in little or no detectable recovery in three years, j
period that proved adequate  for  substantial  recovery ir
Lake Washington (Emery et  al. 1972).86 Lake Sebasticook
Maine, affords another example of undesirable enrichment
Although previously in an acceptable condition, it became
obnoxious during the  1960's in response  to sewage and £
wide  variety  of industrial  wastes  (HEW  1966).112  The
nutrient  income  of Lake Winnisquam, New  Hampshire
has been studied to  determine the cause of nuisance blooms
of blue-green algae (Edmondson 1969).82 The  well-knowr
Jakes  at Madison, Wisconsin,  including Monona, Waubesa,
and Mendota, have been the object of detailed studies 01
nutrient  sources  and their  deteriorating effect on water
quality (Sawyer  1947,106 Mackenthun  et al.  I960,95 Ed-
mondson  1961,80  1968).81
  A desirable  aspect of eutrophication  is the ability ol
mesotrophic or slightly eutrophic lakes typically to produce
greater crops of fish than their oligotrophic or nutrient-pooi
counterparts. As long as nuisance blooms of algae  anc
extensive  aquatic weed beds  do not hinder the growth o
desirable  fish  species  or obstruct  the mechanics  and aes-
thetics of fishing or other beneficial uses,  some enrichmen
may be desirable. Fertilization is a tool in commercial anc
sport fishery management used to produce greater crops o
fish. Many prairie  lakes in the east slope  foothills of the
Rocky Mountains would be classed as eutrophic according
to the characteristics discussed below,  yet many of thes<
lakes  are  exceptional trout producers because  of the  higl
natural fertility of the prairie (Sunde et al. 1970).108 As at
example  of an accepted  eutrophic condition, their water
are dense with plankton, but few would consider  reducing
the enrichment of these lakes.
  Streams and estuaries, as  well as lakes, show symptom:
of over-enrichment, but there is less opportunity for builduj
of nutrients because of the  continual transport  of water
Although aquatic growths can develop  to nuisance  pro
portions in streams  and estuaries as a result of over-enrich
ment, manipulation of the nutrient input can modify tht
situation more rapidly than in lakes.
  Man's fertilization of some: rivers, estuaries,  and marine
embayments has  produced undesirable  aquatic growths o
algae, water weeds, and slime: organisms such as Cladophora

                                                          Factors Influencing the Recreational and Aesthetic Value of Water/21
  Ulva, Potamogeton, and Sphaerotilus. In addition to interfering
  with other uses, as in  clogging  fishing  nets with slime
  (Lincoln and Foster  1943),94  the  accompanying water-
  quality changes  in some instances upset the natural fauna
  and flora and cause undesirable shifts in the species compo-
  sition of the community.

  Determination of Trophic Conditions
    It should be emphasized that (a)  eutrophication has a
  significant relationship to the  use of water for recreational
  and aesthetic  enjoyment  as well as  the  other water uses
  discussed in this book; (b) this relationship may be desirable
  or  undesirable, depending upon the type  of recreational
  and aesthetic enjoyment sought; and (c) the possible dis-
  advantages or  advantages of eutrophication may be viewed
  subjectively as they relate to a particular water use. There
  are no generally accepted guidelines for judging whether a
  state of eutrophy exists or by what criteria it may be meas-
  ured, such as production of biomass, rate of productivity,
  appearance, or change in water quality. Ranges in primary
  productivity and oxygen deficit have  been  suggested  as
  indicative of  eutrophy,  mesotrophy, and oligotrophy  by
  Edmondson (1970)83 and Rodhe (1969),104 but these ranges
  have had no official recognition.
   The trophic state and natural  rate of eutrophication that
  exists,  or would exist, in the absence of man's activities is
  the  basis of reference  in judging man-induced  eutrophi-
 cation.  The  determination of the natural  state in many
 water  bodies will require the  careful examination of past
 data, referral  to  published historical accounts,  recall  by
 "old-timers,"  and perhaps the  examination of sediment
 cores for  indicator species and chemical composition. The
 following guidelines are suggested in determining the refer-
 ence trophic states of lakes or detecting changes in trophic
  states.  Determination  of the  reference  trophic  state  ac-
  companied by studies  of  the nutrient budget may reveal
''that the lake is already in an  advanced  state of eutrophy.
  For temperate lakes, a significant change in indicator com-
  munities  or a significant increase in any of the other four
  indices, detectable over a five-year period  or less,  is con-
 sidered sufficient evidence that accelerated eutrophication
 is occurring. An undetectable change over a shorter period
  would  not necessarily indicate a lack of accelerated eutrophi-
 cation.  A change detectable only after five years may still
 indicate unnaturally accelerated eutrophication,  but five
 years is suggested as a realistic maximum for the  average
 monitoring endeavor. Where cultural eutrophication is sus-
 pected and changes in  indices are not observable,  analysis
 of sediment cores may be necessary to establish the natural
 state.  The dynamic characteristics  and individuality  of
 lakes may produce exceptions to these guidelines. They are
 not infallible indicators of interference with recreation, but
 for  now they may serve as a beginning,  subject to modifi-
 cation  as more complete data on the  range of trophic con-
 ditions and their associated effects become available.
   Primary Productivity   Ranges in the photosynthetic
rate,  measured by  radioactive carbon assimilation, have
been  suggested by Rodhe (1969)104 as indicative of trophic
conditions (Table 1-2).
   Biomass  Chlorophyll a is used as a versatile measure
of algal  biomass. The ranges presented for mean summer
chlorophyll a concentration determined in epilim'netic water
supplies  collected at least biweekly and analyzed according
to  Standard  Methods  (American   Public   Health  Assoc.,
American Water Works Assoc., and Water Pollution Con-
trol Federation 1971)70 are indices of the trophic stage of a
lake:  oligotrophic, 0-4 mg chlorophyll a/m3; eutrophic,
10-100 mg  chlorophyll a/m3.
   These ranges  are  suggested  after  reviewing data on
chlorophyll concentrations and other indicators of trophic
state  in  several lakes throughout the United States and
Canada. Of greatest significance are data from Lake Wash-
ington which show  that during peak  enrichment, mean
summer  chlorophyll a content rose to about 27 mg/m3 and
that the lake was definitely eutrophic. The post nutrient
diversion summer mean  declined to about 7 mg/m3, and
the lake is  now more  typically mesotrophic  (Edmondson
1970;83 chlorophyll a values corrected to conform to recent
analytical techniques).  Unenriched and relatively low pro-
ductive lakes at higher elevations in the Lake Washington
drainage basin show mean summer chlorophyll a contents
of 1 to 2 mg/m3. Moses Lake,  which  can be considered
hypereutrophic,  shows  a summer  mean  of 90  mg/m3
chlorophyll  a (Bush  and Welch 1972).76
   Oxygen Deficit   Criteria for  rate of depletion of  hy-
polimnetic oxygen in relation to trophic state were reported
by Mortimer (1941)96 as follows:

   <250 mg O2/m2/day

>550 mg O2/m2/day
This is the rate  of depletion of hypolimnetic oxygen  de-
termined by the change in mean concentration of hypolim-
netic oxygen per unit time multiplied by the mean depth
of the  hypolimnion. The observed time interval  should be
at least a month, preferably longer, during summer stratifi-
  TABLE 1-2—Ranges in Photosynthetic Rate for Primary
               Productivity Determinations*
Mean daily rates in a growing season, mgC/myday       30-100
Todl annual rates, gC/mVyear   ..       .       7-75
 « Measured by total carbon uptake per square meter of water surface per unit of time. Productivity estimates should
be determined from at least monthly measurements according to Standard Methods.
 American Public Health Association, American Water Works Assot, and Water Pollution Control Federation
1971"; Rodbe IMS.™

 22/'Section I—Recreation and Aesthetics
   Indicator Communities   The representation  of cer-
 tain species in a community grouping in fresh water  en-
 vironments is often a sensitive indicator of the trophic state.
 Nutrient enrichment in streams causes changes in the size
 of faunal  and floral  populations, kinds  of species,  and
 numbers of species (Richardson 1928,103 Ellis 1937,84 Patrick
 1949,"  Tarzwell  and  Gaufin 1953110). For example, in a
 stream  typical of the temperate zone in the eastern United
 States degraded  by organic pollution the following shifts
 in aquatic communities are often found: in the zone  of
 rapid decomposition below  a  pollution  source, bacterial
 counts  are  increased; sludgeworms (Tubificidae),  rattail
 maggots (Eristalis tenax)  and bloodworms  (Chironomidae)
 dominate the benthic fauna; and blue-green  algae and the
 sewage  fungus  (Sphaerohlus) become common  (Patrick
 1949," Tarzwell and Gaufin 1953,110 Patrick et al. 1967100).
 Various blue-green algae such as Schizothrix calcicola,  Micro-
 coleus vaginatus, Microcystis aeruginosa, and Anabaena sp. are
 commonly found  in nutrient-rich  waters, and blooms  of
 these and other algae frequently detract from the aesthetic
 and  recreational  value of lakes. Diatoms  such as Nitzschia
palea, Gomphonema parvulum,  Navicula cryptocephala, Cyclotella
 meneghiniana,  and Melosira varians are  al"O often abundant
 in nutrient-rich water (Patrick and Reimer 1966).101 Midges,
 leeches, blackfly larvae, Physa snails, and fingernail clams
 are frequently abundant in the recovery zone.
  Nutrients  Chemicals  necessary to  the   growth and
 reproduction of rooted or floating  flowering plants, ferns,
 algae,  fungi, or  bacteria are  considered to be  nutrient
 chemicals. All these chemicals are not yet known, but those
 that have been identified are classified as macronutrients,
 trace elements or micronutrients,  and organic nutrients.
 The macronutrients are calcium,  potassium, magnesium,
 sodium, sulfur, carbon and carbonates, nitrogen, and phos-
 phorus.  The micronutrients are silica, manganese, zinc,
 copper,  molybdenum,  boron, titanium, chromium, cobalt,
 and  perhaps vanadium (Chu 1942,77  Arnon and Wessell
 1953,72 Hansen et al. 1954).89 Examples of organic nutrients
 are biotin, Bi2, thiamine,  and glycylglycine (Droop 1962).79
 Some of the amino acids and simple sugars have also been
shown to  be nutrients for heterotrophs or partial hetero-
  Plants vary as to the amounts and kinds of nutrients they
require, and  as a result one  species or group of species of
algae or aquatic plants may gain dominance over another
group because of the variation in concentration of nutrient
chemicals.  Even  though  all the  nutrients  necessary for
plant growth are  present, growth will not  take place unless
environmental factors such as light, temperature, and sub-
strate are suitable.  Man's use of the watershed  also in-
fluences the sediment  load  and nutrient  levels in surface
waters (Leopold et al. 1964,93 Bormann and Likens 1967).75
  Thomas  (1953)111 found  that the  important factor in
artificial eutrophication was the high  phosphorus content
of domestic wastes.  Nitrogen became  the limiting growth
factor if the  algal demand  for phosphorus was met. Nu-
merous studies have verified these conclusions (Americar
Society of Limnology and Oceanography 1972).71
   Sawyer (1947)106  determined critical levels  of inorganic
nitrogen (300 jug/1 N) and inorganic phosphorus (10 jug/
P) at  the time  of spring  overturn in Wisconsin lakes. I
exceeded, these levels would  probably  produce  nuisance
blooms of algae during the summer. Nutrient concentration;
should be maximum when measured at the  spring overturr
and at the  start of  the  growing season. Nutrient concen
trations during  active growth periods may only indicate
the difference between amounts absorbed in biomass (sus
pended and settled) and the initial  amount biologicall)
available. The values, therefore, would not be indicative
of potential algal production.  Nutrient content should \x
determined  at least  monthly (including the time  of spring
overturn) from the surface, mid-depth, and bottom. These
values can be related to water volume in each stratum,  and
nutrient concentrations based on total lake  volume can be
   One of the most convincing  relationships between maxi-
mum phosphate content at the time  of lake overturn and
eutrophication  as indicated by algal biomass has beer
shown in Lake Washington (Edmondson 1970).83 During
the years when algal densities progressed to  nuisance levels.
mean winter PO4-P increased  from 10-20 jug/1 to 57 jug/1.
Following diversion  of the sewage mean PO4-P decreased
once again to the preenrichmerit level. Correlated with the
PO4-P reduction was mean summer chlorophyll a content.
which  decreased from a mean of 27 jug/1 at peak enrichrnenl
10 less  than  10 jug/1,  six years, after diversion was initiated,
  Although difficult to assess,  the  rate of  nutrient inflow
more  closely  represents  nutrient  availability  than does
nutrient concentration because of the dynamic character
of these nonconservative materials. Loading rates are usuall)
determined annually on the basis of monthly monitoring ol
water  flow,  nutrient concentration in  natural  surface and
groundwater, and wastewater inflows.
  Vollenweider (1968)113 related nutrient loading to mear
depths for various well-know a  lakes and identified trophic
states associated with induced  eutrophication.  These find-
ings showed shallow lakes to be clearly more sensitive tc
nutrient income  per unit area than deep  lakes, because
nutrient reuse to perpetuate nuisance growth  of algae in-
creased as depth decreased. From this standpoint nutrient
loading was a more  valid criterion than nutrient concen-
tration in judging trophic state, Examples of nutrient load-
ings which produced nuisance conditions were about  0.3
g/m2/yr P and 4 g/'m2/yr  N for a lake with a mean depth
of 20 meters, and about 0.8 g/m2/yr P and 11 g/m2/yr N
for a lake  with a mean depth of 100 meters.
  These suggested criteria  apply only if other requirements
of algal growth are met,  such as available light and water
retention time. If these factors limit growth rate and  the
increase of biomass,  large amounts of nutrients may move
through the system  unused, and nuisance conditions may
not occur  (Welch 1969).115

                                                    Factors Influencing the Recreational and Aesthetic Value of Water/23
  Carbon (C)  is required by all photosynthetic plants. It
may be in the form of COa in solution, HCO^, or COJ°.
Carbamine carboxylate, which may form by the complexing
of calcium or other carbonates and amino  compounds in
alkaline water, is an efficient source of COa (Hutchinson
1967).90 Usually  carbon is not  a limiting factor in water
(Goldman et al. 1971).88 However, King (1970)92 estimated
that concentrations of CO2 less than 3 micromoles at equi-
librium favored blue-green algae, and concentrations greater
than this favored green  algae.
  Cations such as calcium, magnesium, sodium, and po-
tassium are required by algae  and  higher  aquatic plants
for  growth, but  the optimum  amounts and ratios vary.
Furthermore, few situations exist in which these would be
in such low supply as to be limiting to plants. Trace ele-
ments either singly or in combination are important for the
growth of algae  (Goldman 1964).86  For example molyb-
denum has been  demonstrated to be  a limiting nutrient in
Castle  Lake. Deficiencies in trace elements are more likely
to occur in oligotrophic  than in eutrophic waters (Goldman
  The vitamins important in promoting optimum growth
in algae are biotin, thiamin,  and Bi2. All major groups
require one or more of these vitamins, but particular species
may or may not require them. As Provasoli and D'Agostino
(1969)102 pointed out, little is known about the requirement
for  these vitamins for growth of algae in polluted water.
  Under natural conditions it is difficult to determine the
effect of change  in concentrations of a single chemical on
the growth of organisms. The  principal reasons are  that
growth results from  the  interaction of many  chemical,
physical, and biological factors on  the functioning of an
organism; and that nutrients arise from  a mixture of chemi-
cals from farm, industrial, and  sanitary wastes, and runoff
from fields. However, the  increase in amounts and types of
nutrients can be  traced  by shifts in species forming aquatic
communities. Such biotic shifts have occurred in western
Lake Erie (Beeton 1969).« Since  1900 the watershed of
western Lake Erie has changed with  the rapidly increasing
human population and industrial development, as a result
of which the lake has received large quantities of sanitary,
industrial, and agricultural organic  wastes. The lake has
become modified by increased  concentrations of dissolved
solids, lower transparency, and low dissolved  oxygen concen-
tration. Blooms  of blue-green algae  and shifts in inverte-
brate populations have markedly increased in the 1960's
(Davis 1964, "Beeton  1969).73

Summary of Measurement of Nutrient Enrichment
  Several conditions can be used to measure nutrient en-
richment or its effects:

     • a steady decrease over several years in the dissolved
       oxygen content  of the hypolimnion when measured
       prior to fall overturn, and an increase in anaerobic
       areas in the lower portion of the hypolimnion;
    • an  increase  in  dissolved  materials, especially nu-
      trients such  as  nitrogen,  phosphorus,  and simple
    • an  increase in suspended  solids, especially organic
    • a shift in  the structure of communities of aquatic
      organisms involving a shift in kinds of species and
      relative abundances of species and biomass;
    • a steady though slow decrease in light penetration;
    • an  increase in organic materials and nutrients, es-
      pecially phosphorus, in bottom deposits;
    • increases  in  total phosphorus  in the spr'ng  of the

  The principal recommendations for aesthetic and
recreational uses of lakes, ponds, rivers, estuaries,
and near-shore coastal waters are that  these uses
continue to be pleasing  and undiminished  by  ef-
fects of cultural  activities that increase plant nu-
trients.  The  trophic  level  and natural rate of
eutrophication that exists, or would exist, in these
waters  in the  absence of man's activities is  con-
sidered the reference level and the commonly de-
sirable level to be maintained. Such water should
not have a demonstrable accelerated  production
of  algae  growth in  excess  of rates normally  ex-
pected  for the same type of waterbody in nature
without man-made influences.
  The concentrations of phosphorus and  nitrogen
mentioned  in  the text as leading  to  accelerated
eutrophication were developed from  studies  for
certain aquatic  systems: maintenance  of  lower
concentrations may or may  not prevent eutrophic
conditions. All the factors causing nuisance plant
growths  and the level of each which should not be
exceeded  are  not  known.  However,   nuisance
growths will be limited if the addition of all wastes
such as sewage,  food processing, cannery, and in-
dustrial  wastes  containing nutrients,  vitamins,
trace elements,  and growth stimulants are  care-
fully controlled and nothing is added  that causes
a slow overall  decrease of average dissolved oxygen
concentration in the hypolimnion and an increase
in  the extent and duration of anaerobic conditions.


  Aquatic vascular plants affect water quality, other aquatic
organisms, and the uses man makes of the water. Generally,
the effects are inversely proportional to the volume of the
water body and  directly proportional to the use man wishes
to  make  of  that water.  Thus  the impact  is often most
significant in marshes,  ponds,  canals,  irrigation  ditches,
rivers,  shallow  lakes, estuaries  and  embayments,  public
water supply sources, and man-made impoundments. Dense

241'Section I—Recreation and Aesthetics
growths of aquatic vascular plants are not necessarily due
to human  alteration of the  environment. Where an ap-
propriate environment  for plant growth occurs, it  is ex-
tremely difficult to prevent the growth  without changing
the environment. Addition of plant nutrients can  cause
aquatic vascular plants  to increase to nuisance proportions
in waters where natural fertility levels are insufficient to
maintain dense populations (Lind and Cottam 1969).147 In
other waters where artificial nutrient additions are  not a
problem, natural  fertility alone  may  support  nuisance
growths (Frink 1967).186

Interrelationships With Water Quality
  Through  their metabolic  processes, manner of growth,
and eventual decay, aquatic vascular plants can have sig-
nificant effects on such  environmental factors as dissolved
oxygen and  carbon dioxide, carbonate and  bicarbonate
alkalinity, pH, nutrient supplies, light penetration, evapo-
ration, water circulation,  current velocity, and sediment
composition. The  difficulty  in understanding the  inter-
relationships among  plant growth  and water quality  is
described  in part  by Lathwell et al.  (1969).144  Diurnal
oxygen rhythm with maximum concentrations in the after-
noon and  minimums just before  dawn is a universally-
recognized limnological phenomenon, and metabolic ac-
tivities of vascular plants can contribute to these rhythms.
The effect  of aquatic plants  on dissolved oxygen within a
reach of stream at a particular time  of day is a function of
the plant density and distribution, plant species, light in-
tensity, water depth, turbidity, temperature, and ambient
dissolved oxygen.  Oxygen production  is  proportional to
plant density only  to a certain limit;  when  this limit  is
exceeded,  net oxygen production  begins to decrease and,
with increasing density,  the plants  become net oxygen con-
sumers (Owens et al. 1969).16!) It is hypothesized that this
phenomenon occurs because the plants become  so  dense
that some are shaded by other overlying plants. Westlake
(1966)173 developed  a model for predicting the effects of
aquatic vascular plant density  and distribution on oxygen
balance which demonstrates  that if the weeds are concen-
trated within a small area, the net effect of the weeds may
be to  consume more oxygen  than   that produced,  even
though the average density may be relatively low.
  After reviewing the  literature on the direct effects of
plants on the oxygen balance, Sculthorpe (1967)162 con-
cluded that the extent  of oxygen enrichment at  all  sites
varies with changing light intensity, temperature, and plant
population density and  distribution.  On a cloudy, cool day
community respiration  may exceed even the maximum
photosynthetic rate.  Although vigorous oxygen production
occurs in the growing season, the plants eventually die and
decay, and the resulting oxygen consumption is spread over
the cooler seasons of the year.
  Light penetration  is significantly reduced by dense  stands
of aquatic  vascular plants, and this reduces photosynthetic
rates at shallow depths. Buscemi (1958)129 found that unde:
dense beds  of Elodea  the dissolved oxygen  concentratioi
fell sharply with depth and marked stratification was pro
duced.  Severe oxygen depletion  under  floating mats  o
water hyacinth (Lynch et al. 1947),16° duckweed and wate
lettuce  (Yount 1963)170 have occurred.  Extensive covers o
floating or emergent  plants shelter the  surface from th<
wind, reduce turbulence and reaeration, hinder mixing
and promote thermal stratification. Dense growths of phyto
plankton may also shade-out submerged macrophytes, anc
this phenomenon  is used to  advantage  in  fisheries  pone
culture. Fertilization of ponds to  promote phytoplanktoi
growth  is recommended as a means of reducing the standing
crop of submerged vascular plants (Swingle 1947,167 Surbei
   Interrelationships  of plants with water chemistry were
reported by  Straskraba (1965)16S when foliage of dens<
populations of Nuphar, Ceratophyllum, and Myriophyllum wen
aggregated on the surface. He found pronounced stratifi-
cation of temperature and chemical factors and  reportec
that the variations  of oxygen, pH, and alkalinity  were
clearly dependent on the photosynthesis and respiration oi
the plants. Photosynthesis also involves carbon dioxide, and
Sculthorpe (1967)162 found thai: for every rise of 2 mg/1 ol
dissolved oxygen  the  total carbon dioxide  should  drop
2.75 mg/1 and be accompanied by a rise  in the pH. A rise
in pH will allow greater concentrations of un-ionized am-
monia (see Freshwater Aquatic Life, p.  140).
   Hannan  and Anderson (1971)137 studied diurnal oxygen
balance, carbonate and bicarbonate alkalinity and pH on a
seasonal basis in two Texas ponds less than 1  m deep which
supported dense growths of submerged rooted macrophytes.
One pond  received seepage water containing free carbon
dioxide and supported a greater plant biomass. This pond
exhibited a diurnal dissolved-oxygen range in summer from
0.8 to 16.4 mg/1, and a winter range from 0.3 to 18.0 mg/1.
The other pond's summer diurnal dissolved-oxygen range
was 3.8 to 14.9 mg/1 and the  winter range was 8.3 to 12.3
mg/1. They concluded that (a) when macrophytes use bi-
carbonate as a carbon source, they liberate carbonate and
hydroxyl ions, resulting in an increase in pH and a lowered
bicarbonate alkalinity; and (b) the pH of  a  macrophyte
community is a function of the carbon dioxide-bicarbonate-
carbonate ionization phenomena as altered by photosynthe-
sis and  community respiration.
   Dense colonies of aquatic macrophytes may occupy up
to 10 per cent of the total volume of a river and reduce the
maximum velocity of  the current to less than 75 per cent
of that  in uncolonized reaches (Hillebrand  1950,139 as re-
ported  by Sculthorpe  1967162). This can increase sediment
deposition and lessen channel capacity by raising the sub-
strate, thus increasing the chance of flooding. Newly de-
posited silt  may be quickly stabilized  by aquatic plants,
further  affecting flow.
   Loss of water by transpiration varies between species and

                                                        Factors Influencing the Recreational and Aesthetic Value of Water/25
 growth forms. Otis (1914)168 showed that the rate of tran-
 spiration of Nymphaea odorata was slightly less than the rate
 of evaporation from a free water surface of equivalent area,
 but that of several emergent species was up to three times
 greater. Sculthorpe  (1967)162 postulated that transpiration
 from the leaves of free-floating rosettes could be at rates six
 times greater than evaporation from an equivalent  water
 surface. Loss of water through water hyacinth was reported
 by Das (1969)133 at 7.8  times that of open water.

 Interrelationships With  Other Biota
  Aquatic  macrophytes provide a direct or indirect source
of food for aquatic invertebrates and fish and for wildlife.
The plants provide increased substrate for colonization by
epiphytic algae,  bacteria, and other microorganisms which
provide food for the larger invertebrates  which, in turn,
provide food for fish. Sculthorpe (1967)162 presented a well-
documented  summary of the importance of a wide variety
of aquatic macrophytes to fish, birds, and  mammals. Sago
pondweed  (Potamogeton  pectmatus) illustrates  the opposite
extreme in  man's attitude toward  aquatic macrophytes:
Timmons (1966)168  called it  the most noxious  plant  in
irrigation  and drainage  ditches  of the American  west,
whereas Martin  and Uhler (1939)166 considered it the most
important duck food plant in the United States.
  Aquatic vegetation and flotage breaking the water surface
enhance mosquito production by  protecting larvae from
wave  action  and aquatic predators and interfering with
mosquito control procedures. Two major vectors of malaria
in the United States are Anopheles quadnmaculatus east  of the
Rocky Mountains, and A. freeborni to the west (Carpenter
and La Casse 1955).130 Anopheline mosquitoes are generally
recognized as permanent pool breeders. The more important
breeding sites of these two mosquitoes are freshwater lakes,
swamps, marshes, impoundment margins, ponds, and seep-
 age areas (Carpenter and La Casse 1955).130 The role  of
various aquatic  plant types in relation to the production
 and control  of A. quadnmaculatus on artificial  ponds and
reservoirs indicates that the greatest problems are created
by macrophytes  that are  (1)  free-floating, (2) submersed
 and anchored but which break the water surface, (3) floating
leaf anchored, and (4) emersed floating-mat anchored (U.S.
Department  of  Health, Education,  and Welfare,  Public
Health Service,  and Tennessee  Valley Authority 1947).169
 In addition  to  vector  mosquitoes,  pestiferous  mosquitoes
develop in association with plant parts in shoreline  areas.
 Jenkins  (1964)142 provided an annotated  list  and  bibli-
 ography of  papers  dealing with aquatic vegetation and
  Generally, submersed vascular plants have lower nutrient
 requirements than  filamentous algae  or  phytoplankton
 (Mulligan and Baranowski 1969) ,157 Plants with root systems
 in the substrate do not have to compete with phytoplankton,
 periphyton, or non-rooted macrophytes for the phosphorus
 in the  sediments.
  Boyd (1971b),126 relating his earlier work on emergent
species  (Boyd 1969,122 1970a,123 197la125) to that of Stake
(1967,163 1968164) on submerged species, stated that in the
southern United States most  of the total net nutrient ac-
cumulation by aquatic vascular plants occurs by midspring
before peak dry matter standing crop is reached, and that
nutrients stored  during early spring growth are utilized for
growth later. Thus nutrients are removed from the environ-
ment early in the season, giving the  vascular hydrophytes
a competitive advantage over phytoplankton. Boyd (1967)121
also reported that the quantity of phosphorus  in aquatic
plants frequently exceeds that of the total water volume.
These phenomena may account for the high productivity
in terms of macrophytes which can occur in infertile waters.
However, if the  dissolved phosphorus level is not  a limiting
factor for the phytoplankton, the ability to utilize sediment
phosphorus is not a competitive advantage for rooted plants.
  Further interaction between aquatic vascular plants and
phytoplankton has  been demonstrated recently  in  studies
showing that concentrations of dissolved organic matter can
control plant growth in lakes by regulating the availability
of trace metals and other nutrients essential to plant photo-
synthesis. An array of organic-inorganic interactions shown
to suppress plant growth in hardwater lakes (Wetzel 1969,174
1971176) appear  to operate in  other lake types and streams
(Breger 1970,127 Malcolm et  al. 1970,162 Allen  1971116).
Wetzel and Allen in press (1971)176 and Wetzel and Manny
(1972)177 showed that aquatic macrophytes near inlets of
lakes can  influence phytoplankton growth by  removing'
nutrients as they enter the lake while at the same  time
producing  dissolved organic compounds that complex with
other nutrients necessary to phytoplankton growth. Manny
(1971,153 1972154)  showed several  mechanisms  by which
dissolved  organic nitrogen  (DON)  compounds regulate
plant growth and rates of bacterial nutrient regeneration.
These control mechanisms can be disrupted by  nutrients
from municipal  and agricultural wastes and dissolved or-
ganic matter from inadequately treated wastes.

Effects on Recreation and Aesthetics
  It is  difficult  to estimate the magnitude of the adverse
effects of aquatic macrophytes in terms of loss of recreational
opportunities or degree of interference with recreational
pursuits. For example, extensive growths of aquatic macro-
phytes interfere  with boating of all kinds; but the extent of
interference depends,  among other things, on the  growth
form of the plants,  the  density  of  the colonization, the
fraction of the waterbody covered, and the purposes, atti-
tudes, and tolerance of the boaters. Extremes of opinion on
the degree of impact create difficulty  in estimating a mone-
tary, physical, or psychological loss.
  Dense growths of aquatic macrophytes are generally ob-
jectionable to the swimmer, diver, water skier, and scuba
enthusiast. Plants or plant parts can  be at least a nuisance
to  swimmers and,  in extreme cases, can  be a  factor in

26/'Section I—Recreation and Aesthetics
drowning. Plants obstruct a diver's view of the bottom and
underwater hazards, and fronds can become entangled in
a scuba diver's gear. Water skiers' preparations in shallow
water are hampered by dense growths of plants,  and fear
of falling  into such growths while skiing detracts  from en-
joyment of the sport.
  Rafts of free-floating plants  or attached plants which
have  been dislodged from  the substrate  often drift  onto
beaches or into swimming areas, and time and labor are
entailed in restoring their attractiveness. Drying and decay-
ing aquatic plants often produce objectionable odors and
provide breeding areas  for a variety of insects.
  Sport fishermen have  mixed feelings about aquatic macro-
phytes.  Fishing is often good around patches of lily pads,
over deeply-submerged  plants, and on the edges of beds of
submerged weeds which rise near the surface. On the other
hand, dense growths may restrict the movement and feeding
of larger  fish  and limit the fishable area  of a waterbody.
Aquatic plants entangle lures and baits  and can prevent
fishermen from reaching desirable fishing areas.
  Marshes and aquatic macrophytes in sparse or moderate
densities along watercourse and waterbody margins  aug-
ment nature study and shoreline exploration and add to the
naturalistic value of camping  and recreation  sites.  It is
only  when  the density of  the growths,  or their growth
forms, become a nuisance  and interfere with man's ac-
tivities that he finds them objectionable. An indication of
how often that occurs is provided  by McCarthy (1961),156
who reported that on the basis of a questionnaire sent to
all states in 1960, there were over 2,000 aquatic vegetation
control projects conducted annually, and that most states
considered excessive growth of aquatic vegetation a serious
and increasing problem.
   The  aesthetic  value  of aquatic macrophytes is in the
mind of the beholder. The age-old appeal of aquatic plants
is reflected in their importance as motifs in ancient archi-
tecture, art, and mythology.  Aquatic gardens continue to
be  popular tourist attractions  and  landscaping  features,
and wild  aquatic plant communities have strong appeal to
the  artist, the photographer, and  the public. To many,
these plants make a contribution of their own to the beauty
of man's environment.

Control Considerations
   Aquatic vascular  plants  can be controlled  by several
methods: chemical (Hall  1961,136 Little 1968148); biological
(Avault et al. 1968,117  Maddox et al. 1971,161 Blackburn
et al. 1971120); mechanical   (Livermore  and  Wunderlich
1969149); and naturalistic environmental manipulation (Pen-
found 1953).160 General reviews of control techniques have
been made by Holm et al.  (1969),141 Sculthorpe  (1967),162
and Lawrence (1968).145
   Harvesting aquatic vascular plants to  reduce  nutrients
as a means of eutrophication control has been investigated
by Boyd  (1970b),124 Yount and Grossman  (1970),171 an
Peterson (1971).161 Although  many investigators have n
ported important nutrients in various aquatic  plants, tr
high moisture content of the  vegetation as it is harveste
has been an impediment to economic usefulness. Peterso
(1971)161 reported the cost per pound of phosphorus, n
trogen,  and carbon removed from a large lake supportin
dense growths of aquatic vascular plants as $61.19, $8.2
and $0.61 respectively.
  Nevertheless, improved methods of harvesting and proc
essing promise to reduce the costs of removing these bothei
some plants and  reclaiming their nutrients for animal an
human  rations or for soil enrichment.  Investigation int
the nutritive value of various aquatic plants has frequentl
been an adjunct of research on the efficiency and econom
of harvesting and processing  these plants in a a effort  t
remove  nuisance  growth from lakes and streams. Extensiv
harvesting of aquatic vegetal ion from plant-clogged  Cadd
Lake  (Texas-Louisiana)  was  followed by  plant analysi
and feeding trials. The dehydrated material was found to b
rich in protein and xanthophyll (Cregeretal. 1963,132 Couc
et al.  1963131). Bailey (1965)llfl reported an average of 38'
milligrams of xanthophyll per  pound of vacuum oven-driei
aquatic plant material with  about  19 per  cent proteir
Hentges (1970),13S in cooperation  with Bagnall (1970),'
in preliminary tests with cattle fed press-dehydrated aquati
forage,  found  that  pelleted  Hydrilla  verticillata  (Florid
elodea)  could be fed satisfactorily as 75 per  cent of a bal
anced  ration. Bruhn et  al.  (1971)128  and  Koegel  et al
(1972)143 found 44 per cent mineral and 21 per cent protei
composition in  the dry matter of the heat coagulum  of th
expressed juice  of Eurasian  water  milfoil  (Myriophyllw
spicatum).  The  press residue,  further reduced  by cuttin
and pressing to  16 per cent of the  original volume and 3
per cent of the  original weight, could readily be spread fo
lawn or garden mulch.
  Control  measures are  undertaken  when  plant growt
interferes  with human  activities beyond some ill-define-
point, but too little effort has been expended to determin
the causes of infestations and  too  little concern has bee
given the  true  nature of the  biological problem  (Boyi
1971b).126 Each aquatic macrophyte  problem under con
sideration for control should  be  treated as unique,  th
biology of the plant should tie well understood,  and all th
local factors thoroughly  investigated before  a technique i
selected. Once aquatic macrophytes  are killed, space fo
other plants becomes available. Nutrients contained  in th
original plants  are released for use by other  species.  Long
term  control normally requires  continued efforts.  Herbi
cides may be directly toxic to fish, fish eggs, or invertebrate
important as fish food  (Eipper  1959,134 Walker  1965,1'
Hiltibran 1967).140 (See  the  discussion of Pesticides,  pp
182-186,  in Section III.) C'n man-made lakes, reservoir
and ponds the potential for invasion by undesirable aquati

                                                       Factors Influencing the Recreational and Aesthetic Value of Water/27
plants may be lessened by employing naturalistic methods
which limit the available habitat and requirements of par-
ticular species. It is difficult to predict what biotic form will
replace the species eliminated. Boyd  (1971 b)126 states that
in some Florida  lakes, herbicide  applications have  upset
the balance between rooted aquatics and phytoplankton,
resulting  in  nuisance  phytoplankton blooms  that  were
sometimes more objectionable than the original situation.
  Control of aquatic vascular plants can be  a  positive
factor in fisheries management (Leonard and Cain 1961) ;146
but when control projects  are contemplated in  multi-pur-
pose waters, consideration should be given to existing inter-
dependencies between man and the  aquatic community.
For example:  what  biomass of aquatic vascular plants is
necessary  to support waterfowl; what biomass will permit
boating; what is a tolerable condition for swimming;  must
the shoreline be clear of plants  for wading;  will  shore
erosion increase if the shoreline vegetation is removed? The
interference of aquatic vascular plant communities in human
activities should be controlled with methods that stop  short
of attempted plant eradication.

  The complex interrelationships among aquatic
vascular  plants, associated  biota,  water quality,
and the  activities of humans call for case-by-case
evaluation in assessing the need for management
programs. If management is undertaken, study of
its potential impacts on the aquatic ecosystem and
on various  water uses should precede its  imple-


Extent and Types of Introductions
  Purposeful or accidental introductions  of foreign aquatic
organisms or transplantations of organisms from one drain-
age system to another can profoundly influence the aesthetic
appeal  and the  recreational  or commercial potential  of
affected waterbodies. The  introduction of a single species
may alter an  entire  aquatic  ecosystem  (Lachner et  al.
1970).188 An example of extreme alteration occurred with
the invasion of the Great Lakes by the sea lamprey (Petro-
myzon marinus) (Mofiett 1957,190 Smith 1964197). Introduced
and  transplanted species account for about half of the fish
fauna of Connecticut (Whitworth et al. 1968),199 California
(Shapovalov  et al.  1959),195  Arizona, and  Utah  (Miller
1961).189 The nature of the  original  aquatic fauna is ob-
scured in many  cases, and some indigenous species  have
been adversely  affected through predation,  competition,
hybridization, or alteration of habitat  by the  introduced
species. Exotics that have established reproducing popu-
lations in the  United  States (exclusive of the Hawaiian
Islands) include 25 species offish (Lachner et al. 1970),18g
more than 50 species of land and aquatic mollusks (Abbott
1950),178 and over 20  species  of aquatic  vascular plants
(Hotchkiss 1967)185 in addition to aquatic rodents, reptiles,
amphibians, insects, and crustaceans.
  Growths of native aquatic vascular plants and a variety
of exotic species  commonly interfere with recreation  and
fishing activities  (see  p. 25) and a variety  of other water
uses including industrial and agricultural  use (Holm et al.
1969,184 Sculthorpe 1967).194  Water hyacinth  (Eichhornia
crassipes) caused loss of almost $43 million through combined
deleterious effects in  Florida,  Alabama,  Mississippi,  and
Louisiana in  1956 (Wunderlich 1962).200 Penfound  and
Earle (1948)m estimated that  the  annual loss  caused by
water  hyacinth  in Louisiana   before the  growths  were
brought under control  averaged $5 million and in some
years reached $15  million. Water chestnut (Trapa natans)
produced beds covering 10,000 acres within ten years of its
introduction  near Washington, D.C. (Rawls 1964).193 The
beds blocked navigation  and  provided breeding sites  for
mosquitoes, and their hard spined seed cases on the shore-
lines and  bottom were  a serious nuisance  to  swimmers,
waders, and  people walking the shores.  Eurasian milfoil
(Myriophyllum spicatum) infested 100,000 acres in Chesapeake
Bay. The plants blocked navigation, prevented recreational
boating and  swimming,  interfered with  seafood  harvest,
increased  siltation, and  encouraged mosquitoes  (Cronin
  Invertebrate introductions include the Asian clam  (Cor-
bicula mamlensis), a serious pest in the clogging of industrial
and municipal raw water  intake  systems  and irrigation
canals  (Sinclair  1971),196 and an oriental oyster  drill
(Tntonalia japonica) considered the most destructive drill in
the Puget Sound  area (Korringa 1952).187

Some Results of Introductions
  Some introductions of  exotics, e.g., brown trout (Salmo
trutta), and some transplants,  e.g., striped  bass  (Morone
saxatilis) from the Atlantic to the Pacific and coho  salmon
(Oncorhynchus kisutch) from the Pacific to the Great Lakes,
have been spectacularly successful in providing sport  and
commercial fishing opportunities. Benefits of introductions
and transplantations of many species in a variety of aquatic
situations  are discussed by several authors in A Century of
Fisheries in North America (Benson 1970).179
  The success of other introductions has been questionable
or controversial.  In the case of carp (Cyprinus carpis),  the
introduction  actually  decreased  aesthetic values because of
the increased turbidity caused by the habits of the carp.
The increased  turbidity in turn decreased the biological
productivity  of the waterbody.  The presence of carp has
lowered the  sportfishing potential of many waterbodies
because of a variety  of ecological interactions. The grass
carp or white amur (Ctenopharyngodon idella), a recent impor-

28/'Section I—Recreation and Aesthetics
tation, has been reported from several major river systems
including the Mississippi as far north as Illinois  (Lopinot
personal communication 1972).201 Pelzman (1971),191 in recom-
mending against introducing grass carp into  California,
concluded that their impact on established game fish would
be detrimental and that they might become more trouble-
some  than the common carp.  This view was expressed
earlier by Lachner et al. (1970)188 in considering the impact
of establishment of the species in major river systems. The
walking catfish (Glorias batrachus), accidentally released from
outdoor, holding ponds of aquarium fish dealers in southern
Florida, quickly established reproducing populations in a
variety of habitats (Idyll 1969).186 Natural ponds have pro-
duced up to 3,000 pounds per acre of this species and there
is no current American market for its flesh. This aggressive
and omniverous species apparently reduces the entire fresh-
water community to walking catfish (Lachner et al. 1970).188

Introductions by Official Agencies
  The objectives of introductions of new species by agencies
include pond culture;  aquatic plant control; insect control;
forage; predation; and improvement of sport and com-
mercial fishing. Boating, swimming,  and sport and com-
mercial fin and shellfishing are influenced by  water quality
and the biotic community. Lachner  et al. (1970),188 after
reviewing the history of exotic fish releases, concluded that
most  official releases satisfy certain social wishes  but have
not served effective biological purposes, and that some may
result in great biological damage. The guidelines  of Craig-
head  and Dasmann (1966)181 on introduction of exotic big
game species offer an excellent parallel to the considerations
that should precede the introduction  of aquatic organisms.
Such  guidelines call for (a) the establishment of  the need
and determination of the predicted ecological, recreational,
and economic impact; (b) studies of the proposed release
area to determine that it is suitable, that a  niche is vacant,
and  that indigenous  populations  will not be reduced or
displaced;  (c) life history studies of the organism  to de-
termine possible  disease interrelationships,  hybridization
potential,  and the availability of control technology; am
(d) experiments conducted under controlled conditions tha
indicate how to prevent escape of the organism.
  The California Fish and Game  Commission  (Burn
j972)18" investigated  introducing the  pancora (Aegla laevi
laevis), a small freshwater crab, into streams as  a  foo<
for trout to increase natural trout production and spor
fishing potential. The plan was ultimately rejected, but th
on-site studies  in Chile and  the  experimental  work  ii
California illustrate the breadth of consideration necessar
before any informed decision can  be reached. Problem
associated with introductions of aquatic animals were th
subject of two recent symposia (Stroud 1969;198 Departmen
of Lands  and Forests,  Ottawa 1968183).  Persons contem
plating  introductions are referred for guidelines  to  th
Committee on Exotic Fishes and Other Aquatic Organism
of The  American Fisheries  Society.  This committee ha
representation from the American Society of Ichthyologist
and Herpetologists and is currently  expanding the scope c
its membership to include other disciplines.

  Introduction or  transplantation of aquatic orga
nisms are factors that can affect aesthetics, boat
ing,  swimming,  sport and commercial fin am
shellfishing, and  a  variety of other  water uses
Thorough investigations of an organism's potentia
to alter  water  quality, affect  biological relation
ships, or interfere with other water  uses shoul(
precede any planned  introductions or  transplan
  The deliberate introduction of non-indigenou
aquatic vascular plants, particularly in the warme
temperature  or  tropical  regions,  is  cautione<
against because of the high potential of such plant
for impairing recreational and aesthetic values
Aquaculturists and others should use care to pre
vent  the accidental release of foreign species fo
the same reasons.

  Historically, public health officials have been concerned
about the role  of sewage-contaminated  bathing  water in
the transmission  of infectious disease.  In 1921, the Com-
mittee on Bathing Places, Sanitary Engineering  Section,
American Public  Health Association,  conducted  a study
"to determine the extent and prevalence of infections which
may be conveyed by means  of swimming pools and other
bathing places"  (Simons et al. 1922).226 The results of the
study,  though inconclusive,  suggested that contaminated
bathing water may  transmit infectious agents to  bathers.
The Committee  attached special importance to  the  data
they collected on epidemics of conjunctivitis and other skin
diseases, middle ear  infections, tonsillitis, pharyngitis, and
nasal sinus  infections  caused  by  contaminated  bathing
waters. However, the 1935 Report of the Committee (now
designated as the Joint Committee on Bathing Places of
the Public Health Engineering Section of the American
Public Health  Association  and the Conference  of State
Sanitary Engineers) included the following statement: "The
summary of the replies in the 1921 report when considered
in the light of known epidemiological evidence, leaves this
committee unconvinced that bathing places are  a major
public health problem even though bathing place sanitation,
because of the health considerations involved, should  be
under careful surveillance of the public health authorities,
and proper sanitary  control of bathing places should  be
exercised" (Yearbook of APHA  1936).202
  The suggested  standards  for design, equipment, and
operation of bathing places that were  part  of the  1935
report included a section entitled "Relative Classification
of Bathing  Areas Recommended"  (Yearbook of APHA
1936).202 This section reads, in part, as follows:
       In passing on waters of outdoor bathing places,  three
     aides are available: (1) the results of chemical analyses
     of the water; (2) the results of bacteriological analysis
     of the water; and (3) information obtained by a sani-
     tary survey of sources of pollution, flow currents, etc.—
     It is not considered practicable or desirable to recom-
     mend any absolute standards of safety for the waters
     of outdoor bathing places on any of the three above
  In 1939 (Yearbook of APHA 1940)203 and again in 1955
(Yearbook of APHA 1957),204 the Joint Committee surveyed
all state health departments for  additional information on
reported cases of illness attributable to bathing places, but
these  surveys  uncovered little definite  information. Con-
taminated bathing waters were suspected in cases of sleeping
sickness, sinus infections, intestinal upsets, eye inflammation,
"swimmers itch", ear infections,  and leptospirosis.
  Several  outbreaks  of human leptospirosis, which is pri-
marily an infection of rats and dogs, have been associated
with recreational  waters  contaminated by the urine  of
infected animals (Diesch and McCulloch  1966).210  One
source of infection to man is  wading or swimming in waters
contaminated  by cattle  wastes  (Williams et  al. 1956,231
Hovens et al.  1941216). Leptospirosis is prevalent  among
"wet  crop" agricultural workers, employees of abattoirs,
handlers of livestock, and those who swim in stock-watering
ponds. The organism is not ingested  but enters the body
through breaks in  the skin and  through intact mucous
membrane, particularly the  conjunctiva.
  The most  recent reports  on disease  associated  with
swimming suggest that a free-living, benign, soil and water
amoeba of the  Naegleria group (Acanthamoeba)  may be  a
primary pathogen of animals and man.  Central nervous
system amoebiasis is usually considered a complication of
amoebic dysentery due to E. histolyhcal; however, recent
evidence proves that  Naegleria  gruben  causes  fulmenting
meningoencephalitis   (Callicot   1968,208  Butt  1966,207
Fowler  and Carter  1965,212 Patras and Andujar 1966224).
The amoeba may penetrate the mucous membrane. Free-
living amoebae and their cysts  are rather ubiquitous in
their  distribution  on  soil  and  in  natural waters;  and
identifiable disabilities from free-living amoebae, similar to
the situation with leptospirosis,  occur so rarely as a result
of recreational swimming in the United  States that  both
may  be  considered  epidemiological  curiosities  (Cerva
  In 1953, the Committee on Bathing Beach Contamination
of the Public Health Laboratory Service of England and
Wales began  a five-year study  of the risk to health  from

    ection I—Recreation and Aesthetics
bathing in sewage-polluted sea water and considered "the
practicability of laying down bacteriological standards for
bathing beaches  or  grading them according to degree of
pollution to which  they  are  exposed" (Moore 1959).222
This committee concluded in 1959 that "bathing in sewage-
polluted sea water carries only a negligible risk to health,
even on beaches that are aesthetically very unsatisfactory."
  The consensus among persons who  have studied the
relationship  between bathing  water quality and bathers'
illness appears to be that scientific proof of a direct relation-
ship is lacking, yet there is evidence to  suggest that some
relationship exists. Some experts contend that outbreaks of
illness  among bathers have not  been studied  thoroughly
with modern epidemiologic techniques, and that if such
occurrences were to be studied vigorously, specific knowl-
edge about  the relationship of bathing water quality to
infectious disease would be established. In some studies
where  bathing water  was apparently implicated in the
transmission of disease agents, the water quality was rela-
tively poor, yet no attempts were made to define the specific
  Water quality requirements  for recreational  purposes
may be divided into two categories:  (1) general require-
ments that pertain to all recreational waters, and (2) special
requirements, usually more restrictive,  for  selected  recre-
ational use of water.

Aesthetic Considerations

  As has been stressed earlier in this Section (See Applying
Recommendations, p. 10), all waters should be aesthetically
pleasing, but the great variety of locales makes it impossible
to apply recommendations without considering the par-
ticular contexts. Color of swamp waters would hardly be
acceptable for clear mountain streams. Specific recommen-
dations should reflect  adequate study of local background
quality and should consider fully the inherent variability
so that the designated values will be meaningful. Therefore,
specific local recommendations  might  better  encompass
ranges, or a daily average  further defined by a sampling
period, and  possibly an absolute maximum or minimum as
appropriate. The best  technical thought should be given to
establishment of  such values rather than dependence on
administrative or judicial decision.


   All  recreational surface  waters will be aestheti-
cally  pleasing if they meet the recommendations
presented  in  the discussion of Water Quality for
Preserving Aesthetic Values  in this Section,  p.  12.
Microbiological Considerations
  The hazard  posed  by  pathogenic  microorganisms i
recreational water not intended for bathing and swimmin
is obviously less than it would be if the waters were used fo
those purposes, but it is not piossible to state to what degret
Although  there is  a paucity -of epidemiological  data o
illnesses caused by bathing and swimming, there appear t
be no data that analyze the relationship of the quality c
recreational waters not intended for bathing and swimmin
to the health of  persons  enjoying such  waters.  Criteri
concerning the presence  of microorganisms in water fo
general recreation purposes ;ire not known.

  No  specific  recommendation  concerning  th
microbiological  qualities  of general recreations
waters is presented. In most cases of gross micro
biological pollution of surface waters, there will b
concomitant foreign substance of such magnitud
as to cause the water  to  be aesthetically unac

Chemical Considerations
  The human body is capable of tolerating greater concen
trations of most chemicals upon occasional contact with o
ingestion of small  quantities of water than are most form
of aquatic life. Therefore, specific recommendations for th
chemical characteristics of a.ll recreational waters  are nc
made  since such  recommendations  probably would b
superseded by recommendations for the support of variou
forms of desirable aquatic life.  (See  Sections III and IV
Freshwater and Marine Aquatic Life and  Wildlife.)

  No  specific recommendation  concerning  th
chemical characteristics  of general recreations
waters is presented. However, the following genera
recommendations are applicable:

• recreational waters  that contain chemicals ii
  such concentrations  as  to be toxic to  man  i
  small quantities are ingested  should not be use
  for recreation;

• recreational waters  that contain chemicals ii
  such concentrations  as  to be  irritating  to th
  skin or mucous membranes of the human bod
  upon brief immersion are undesirable.


  Since bathing and  swimming involve  intimate huma
contact with water, special water  quality requiremeni
apply to designated bathing and swimming areas. Thes

                                                          Water Quality for General Recreation, Bathing, and Swimming/31
requirements are based on microbiological  considerations,
temperature and pH, and clarity and chemical character-
istics. They are  more precise than the requirements  for
general recreational waters. If a body of water cannot meet
these specialized requirements, it should not be designated
a bathing and  swimming area but may be designated  for
a recreational use that does not involve planned immersion
of the body.
Microbiological Considerations
  All recreational  waters should  be sufficiently  free  of
pathogenic bacteria so  as not to pose hazards to  health
through  infections, but  this  is a  particularly important
requirement  for  planned bathing and swimming areas.
Many  bodies of water receive untreated or inadequately
treated human  and animal wastes that are a potential focus
of human infection.
  There  have been several attempts to determine the spe-
c'fic hazard to  health from  swimming in sewage-contami-
nated water. Three related studies have been conducted
in this country, demonstrating that an appreciably higher
overall illness incidence may be expected among swimmers
than among nonswimmers, regardless of the quality of  the
bathing  water  (Smith et al.  1951,229  Smith and Woolsey
1952,227 1961228). More than one half of the illnesses reported
were of the eye, ear, nose, and throat type;  gastrointestinal
disturbances comprised up to  one-fifth; skin irritations and
other illnesses made up the balance.
  Specific correlation between  incidence  of  illness and
bathing in waters of a particular bacterial quality was  ob-
served in  two  of  the  studies. A statistically significant
increase  in the incidence of  illness was observed  among
swimmers who used a Lake Michigan beach  on three se-
lected  days of  poorest water quality  when  the mean total
coliform content was 2,300 per 100 ml. However, only the
data concerning these  three  days could  be  used  in  the
analysis  and differences  in illness were not noted in com-
parison with a control beach  over the total season  (Smith
et al. 1951).229  The second instance of positive correlation
was observed in an Ohio River study where it was shown
that, despite the relatively low incidence of gastrointestinal
disturbances, swimming in river  water having a median
coliform density of 2,700 per 100 ml appears to have caused
a statistically significant increase in illnesses among swim-
mers (Smith and Woolsey 1952).227 No relationship between
illness  and water quality was observed  in the  third study
conducted at salt  water beaches on Long Island Sound
(Smith and Woolsey  1961).228
  A study in England suggested that sea water carries only
a  negligible risk to health  even on beaches  that were
aesthetically unsatisfactory  (Moore 1959).222 The minimal
risk attending such  bathing  is  probably associated with
chance contact with fecal  material  that may have come
from infected persons.
  Neither  the  English  nor the United States  salt water
beach studies indicated a causal or associated relationship
between water quality  and disease among swimmers and
bathers.  While the two  United States  fresh water studies
suggested some presumptive relationship, the findings were
not definitive enough to establish specific values for micro-
biological water quality characteristics.
  Tests using fecal coliform bacteria are  more indicative
of the  possible presence of enteric pathogenic microorga-
nisms from man or other warm-blooded animals than the
coliform group of organisms. The data for total  coliform
levels of the Ohio River  Study  were  reevaluated to  de-
termine comparable levels of fecal coliform bacteria (Geld-
reich 1966).213  This reevaluation suggested that a density
of 400 fecal coliform organisms per 100 ml was the approxi-
mate equivalent of 2,700 total coliform organisms per  100
ml. Using  these data as a basis, a geometric mean of 200
fecal coliform organisms per 100 ml has  been recommended
previously  as a limiting value that under  normal circum-
stances should not be exceeded in water intended for bathing
and swimming (U.S. Department of the Interior, FWPCA
  There may be some merit to the fecal coliform index as an
adjunct in determining the acceptability of water intended
for bathing and swimming, but caution should be exercised
in using it. Current epidemiological data are not materially
more refined or definitive than those that were available in
1935. The  principal value of a fecal coliform index is as an
indicator of possible fecal contamination from man or other
warm-blooded animals.  A study of  the occurrence  of
Salmonella  organisms in natural waters  showed  that  when
the fecal coliform level was less than 200 organisms per 100
ml,  this group of pathogenic bacteria was isolated  less
frequently (Geldreich 1970).214 Salmonella  organisms were
isolated  in 28 per  cent of the samples with a fecal coliform
density less than the 200 value,  but they  were  isolated in
more than 85 per cent of the samples that exceeded the
index value of 200 fecal coliform per 100 ml, and in more
than 98 per  cent of the  samples with  a fecal  coliform
density greater than 2,000 organisms per 100 ml.
   In evaluating microbiological  indicators of recreational
water quality, it should be remembered that many of the
diseases that seem  to be causally related to swimming and
bathing in polluted water are not enteric diseases or are
not caused by enteric  organisms.  Hence, the presence of
fecal coliform  bacteria or of Salmonella sp. in recreational
waters  is  less  meaningful  than  in drinking  water.  Indi-
cators other than  coliform or fecal coliform have been sug-
gested from  time to time  as being more appropriate for
evaluating bathing water quality. This includes the staphylo-
cocci (Favero et al. 1964),211 streptococci and other entero-
cocci (Litsky et al. 1953).218 Recently Pseudomonas aerugmosa,
a common organism implicated  in ear infection,  has been
isolated from natural swimming waters (Hoadley 1968)216

yi/Section I—Recreation and Aesthetics
and  may prove to be an indicator of health hazards in
swimming water.  Unfortunately, to date,  none of the al-
ternative  microbiological indicators have  been supported
by epidemiological evidence.
  When used to supplement other evaluative measurements,
the fecal coliform index may be of value in  determining the
sanitary quality of recreational water intended for bathing
and  swimming. The  index is a measure of the  "sanitary
cleanliness" of the water and may denote the possible
presence of untreated or inadequately treated human wastes.
But it is an index that should be used only in conjunction
with other evaluative parameters of water quality such as
sanitary surveys,  other biological indices of pollution, and
chemical analyses of water. To use the fecal coliform index
as the  sole measure of "sanitary cleanliness," it would be
necessary to know the maximum "acceptable" concentra-
tion  of  organisms; but there is no agreed-upon value that
divides  "acceptability" from "unacceptability."* Thus, as
a measure of "sanitary cleanliness," an increasing value in
the fecal coliform index denotes simply a decrease  in the
level of cleanliness of the water.

  No specific recommendation is made concerning
the  presence or concentrations of microorganisms
in bathing water because of the paucity of valid
epidemiological data.

Temperature Characteristics

  The temperature of natural waters is an important factor
governing the character and extent of the recreational ac-
tivities, primarily in the  warm months of the year. Persons
engaging in winter water recreation such as ice skating,
duck hunting,  and fishing do so with the knowledge that
whole  body immersion must be avoided.  Accidental im-
mersion in water  at or near freezing temperatures is  dan-
gerous  because the median  lethal immersion time  is less
than 30 minutes for children  and most  adults  (Molnar
1946).220 Faddists swim in water that is near the freezing
temperature, but  their immersion time is short, and  they
have been  conditioned  for  the  exposure.  As a result  of
training, fat insulation, and increased body heat production,
some exceptional  athletic individuals (Korean pearl divers
and  swimmers of the English channel)  can withstand pro-
longed  immersion for as long as 17 hours in water at  16 C
(61 F),  whereas children and some adults might not survive
beyond two hours (Kreider 1964).217
  From one individual  to another,  there  is considerable
variation in the rates of body cooling and  the incidence of
          TABLE 1-3—Life Expectancy in Water
  (Expected duration in hows for adults wearing file vests and immersed in waters of varying temperature)
Temperature of the water
59 61
15 20
Hr S
M "I
104 P=
40 C°
  * If an arbitrary value for the fecal coliform index is desired, con-
sideration may be given to a density value expressed as a geometric
mean of a series of samples collected during periods of normal seasonal
flow. A maximum value of 1,000 fecal coliform per 100 ml could be
 L= Lethal, 100 per cent expectancy of death.
 M= Marginal, 50 per cent expectancy of unconsciousness, probably drowning.
 S=Sale, 100 per cent survival.
 Adapated from tables by Pan American Airways and others.
survival in cold water. The variability is a function of bod
size, fat content, prior acclimatization, ability to exercise
and overall physical  fitness.  The  ratio of body mass t
surface area is greater in large, heavy individuals, and the!
mass changes with temperature more slowly than that of
small child (Kreider 1964).217
  With the exception of water temperatures affected b
thermal springs,  ocean currents such as the Gulf Strean:
and man-made  heat,  the temperature  of natural water i
the result of air temperature:, solar radiation, evaporatior
and wind movement. Many natural waters are undesirabl
cold for complete body immersion even during the summe
period. These include  coastal waters subjected to cold cut
rents such as the Labrador Current on the northeaster
coastline or the  California Current in the Pacific Ocea
(Meyers et al. 1969).219 In a.ddition, some deep  lakes an
upwelling springs, and streams  and lakes fed from meltin
snow may have summer surface temperatures too cold fc
prolonged swimming for children.
  The most comfortable temperature range for instructions
and general recreational swimming where the  metaboli
rate of  heat production is not high—i.e.,  about 250  kil
calories/hr (1000 BTUs/hr) —appears to be about 29-30 (
(84—86 F). In sprint swimming when metabolic rates excee
500 kilo calories/hr (2,000 BTUs/hr),  swimmers can pei
form  comfortably in water  temperatures in  the range (
20-27 C (68-80 F) (Bullard and Rapp 1970).206
  The safe upper limit of water temperature for recreatiom
immersion varies from individual to individual and seen
to depend on psychological rather than physiological cor
siderations.  Unlike cold water,  the mass/surface  area rati
in warm  water favors the child.  Physiologically, neithe
adult nor child would experience  thermal stress undc
modest  metabolic heat production as long as the wate
temperature was lower than  the normal skin temperatui
of 33 C (91  F) (Newburgh 1949).223 The rate at which hej
is conducted from the immersed human body is so rapi
that thermal balance for a 'body at rest in  water can onl
be  attained if the water temperature is about 34 C (92 J
(Beckman 1963).205 The survival of an individual submerge

                                                     Water Quality for General Recreation, Bathing, and Swimming/ZZ
in water at a temperature above  34-35 C  (93-95  F),
depends on his tolerance  to the elevation of his internal
temperature, and there is a real risk of injury with prolonged
exposure (Table 1-3). Water ranging in temperature from
26-30  C (78-86  F)  is  comfortable to  most  swimmers
throughout prolonged periods of moderate physical exertion
(Bullard and  Rapp  1970).206 Although data are limited,
natural surface waters do not often exceed skin temperature,
but water  at  32 C (90 F) is not unusual for rivers and
estuaries (Public Works 1967).225

  In  recreational  waters  used  for  bathing and
swimming, the thermal characteristics should not
cause an appreciable  increase or decrease in the
deep  body temperature of  bathers and swimmers.
One hour of continuous immersion in waters colder
than  15 C  (59  F) may cause  the death of some
swimmers and  will be extremely  stressful to  all
swimmers who are not garbed in underwater pro-
tective cold-clothing.  Scientific evidence suggests
that  prolonged  immersion in water warmer than
34-35  C (93-94  F) is  hazardous.  The degree of
hazard varies with water temperature, immersion
time, and metabolic rate of the swimmer.

pH Characteristics
  Some chemicals affect the pH of water. Many saline,
naturally alkaline, or acidic fresh  waters may cause  eye
irritation because  the pH of  the water is unfavorable.
Therefore,  special  requirements concerning the  pH  of
recreational waters may  be more restrictive  than those
established for public water supplies.
  The lacrimal fluid of the human eye has a normal pH of
approximately 7.4 and a high  buffering capacity due pri-
marily to the presence of complex organic buffering agents.
As is  true  of many organic buffering agents, those of the
lacrimal fluid are able to maintain the pH within a narrow
range until their buffering capacity is exhausted. When the
lacrimal fluid, through exhaustion of its buffering capacity,
is unable to adjust the immediate contact layer of another
fluid to a pH of 7.4,  eye  irritation results. A deviation of
no more than 0.1 unit from the normal pH of the eye may
result in discomfort, and appreciable deviation will cause
severe pain (Mood 1968).221
  Ideally,  the pH of swimming water should be approxi-
mately the same  as that of the lacrimal  fluid, i.e.,  7.4.
However,  since the lacrimal  fluid  has a high buffering
capacity, a range of pH values from 6.5 to  8.3 can  be
tolerated under average  conditions.  If the water is  rela-
tively free  of dissolved solids and has a very low buffering
capacity, pH values from 5.0 to  9.0 may be acceptable to
most swimmers.
  For most bathing and swimming waters, eye irri-
tation is minimized and recreational enjoyment
enhanced by maintaining the pH within the range
of 6.5 and  8.3 except for those waters with a low
buffer capacity where  a range of pH between  5.0
and 9.0 may be tolerated.

Clarity Considerations
  It is important that water  at  bathing and  swimming
areas be clear enough for users to estimate depth, to see
subsurface hazards  easily  and clearly, and  to  detect  the
submerged bodies of swimmers or divers who may be in
difficulty. Aside from the  safety factor, clear water fosters
enjoyment of the aquatic environment. The  clearer  the
water, the more desirable the swimming area.
  The natural turbidity of some  bathing and  swimming
waters is often so high that visibility through the water is
dangerously limited. If such areas are in conformance with
all other requirements, they may be used for bathing and
swimming, provided that  subsurface hazards are removed
and the depth of the water is clearly indicated by signs that
are easily readable.

  Safety and enhancement of aesthetic enjoyment
is fostered  when  the clarity of the water in desig-
nated bathing and swimming areas allows the de-
tection of subsurface hazards or submerged bodies.
Where such clarity is not attainable, clearly read-
able depth indicators are desirable.

Chemical Considerations
  It is impossible to enumerate in  specific terms  all  the
specialized requirements that pertain to the chemical quality
of bathing and swimming waters. In general, these require-
ments may  be  quantified by analyzing  the  conditions
stipulated  by two kinds of human exposure, i.e., ingestion
and  contact. A  bather involuntarily swallows only a small
amount of water while  swimming, although precise data
on this are lacking.

  Prolonged whole body immersion in the water is
the  principal  activity that influences the required
chemical characteristics of recreational waters for
bathing and swimming.
  The  chemical characteristics of bathing  and
swimming waters  should be such  that water is
nontoxic and nonirritating to  the  skin and  the
mucous membranes of the human body. (See also
the Recommendations on p. 30.)

  The recreational enjoyment of water involves many ac-
tivities other than water contact sports. Some of these, such
as boating, may have an adverse effect on the quality of
water and require  berthing and launching facilities that in
themselves may degrade the  aesthetic enjoyment of the
water  environment. Others,  such as  fishing,  waterfowl
hunting, and shellfish harvesting, depend upon the quality
of water being suitable for the species of wildlife involved.
Because  they are water-related and either require or are
limited by specific water-quality constituents for their con-
tinuance, these  specialized  types of recreation  are  given
individual attention.

  Boating  is a water-based recreational activity that re-
quires aesthetically pleasing water for its full enjoyment.
Boats also make a contribution to the aesthetic and recre-
ational activity scene as the sailboat or canoe glides about
the water  surface  or the  water  skier  performs.  Boating
activity of all types has an element of scale with larger and
faster boats associated with larger waterbodies. Many of
the problems  associated with boating are essentially vio-
lations of scale.
  Boating activities also have  an impact on water quality.
The magnitude of the impact is  illustrated  by recent esti-
mates that  there are more than 12 million pleasure boats in
the United States (Outboard Boating Club  1971).236 More
than  8 million of these are equipped  with engines, and
300,000  have  sanitary facilities without pollution  contro]
devices. Because of the large number of boats in use, many
bodies of water are now experiencing  problems that ad-
versely affect other water uses, such as public water supply,
support  of  aquatic  life, and  other types  of water-based
  The detrimental effect of boating on water quality comes
from  three  principal sources: waste disposal systems, engine
exhaust, and  refuse  thrown  overboard. Discharges  from
waste disposal systems on boats are individually  a small
contribution to  contamination and may not be reflected
in water-quality sampling,  but they represent a potential
health hazard and an aesthetic nuisance that must be co
trolled in or near designated swimming areas.  Pathoge
in human waste are probably the most important contan
nant in the discharges, because of their potential effect i
human health (see discussions on Special Requirements (
Bathing and Swimming Waters, p. 30, and Shellfish, p. 3f
Biochemical oxygen demand (BOD) and suspended soli
(SS) are also involved in the discharges, but the quantiti
are not  likely  to have any  measurable effect on  over:
water quality. In view of this, it would appear that prima
emphasis should be on  the control of bacteria from sanita
  The exhaust of internal combustion engines and the u
burned fuel of the combustion cycle affect aesthetic enjc
ment and may impart undesirable taste and odors to wat
supplies  and off-flavors to  aquatic life.  Crankcase exhai
from  the two-cycle engine  can discharge  as  much as
per cent of the fuel to  the  water in  an unburned sta
while 10 to 20 per cent is common (Muratori 1968).233 O
study showed that the use of 2.2-3.5 gal/acre-foot (usi
an oil:fuel mixture of 1:17) will cause some indication
fish flesh tainting, and about 6 gal/acre-foot result in seve
tainting  (English et al. 1963).232 (For further discussions
the effects of oil on environments, see Sections III and ]
on Freshwater and Marine Aquatic  Life and Wildlife.)
  The amount of lead emitted into the  water from an 01
board motor  burning  leaded gasoline  (0.7 grams of  le
per liter) appears to be related to the size of the  motor a
the speed of operation. A 10-hp engine operated at one-h
to three-fourths throttle was shown to emit into  the wai
0.229 grams of lead  per liter of fuel consumed, whereas
5.6-hp engine operated at full throttle emitted 0.121 grai
per liter (English et al. 1963).232
  With respect to interference with other beneficial us
it has  been reported that a large municipal water works
experiencing difficulties with oil on the  clarification basil
The oil occurs subsequent to periods of extensive weeke
boating  activity during  the recreational season (Orsan
Quality Monitor 1969).234 Moreover, bottles, cans, plasti
and miscellaneous solid wastes  commonly deface wati
where boaters are numerous,  thereby  degrading the  e
vironment aesthetically.

                                                                Water Quality Considerations for Specialized Recreation/35
  Waste discharge including sanitary,  litter, sullage, or
bilge from any water craft substantially reduces the water
quality of harbors and other congested areas.  The practice
is  aesthetically undesirable and  may constitute a health
hazard. When engine emissions from boats spread an oily
film on water or interfere with beneficial uses, as in lowering
the value of fish and other edible  aquatic organisms by im-
parting objectionable taste and odor to their  flesh, restric-
tions  should be devised  to limit  engine  use or reduce the
  Floating or submerged objects  affect boating safety, and
stray electrical currents  increase  corrosion as do corrosive
substances  or low pH values. Growth of hull-fouling orga-
nisms is enhanced by the discharge of high-nutrient-bearing
wastewaters. These conditions represent either a hazard to
boating or an economic loss to the boat operator.

  Water that meets  the general recommendations
for aesthetic purposes is acceptable for boating.
(see Water Quality for Preserving Aesthetic Values,
pp. 11-12.)
  Boats and the impact of boating on water quality
are factors affecting  the recreational and aesthetic
aspects of water use and should be  considered as

  Fish, waterfowl, and  other water-dependent wildlife are
an  integral part  of water-based  recreation activities and
related aesthetic  values. Wildlife enhances  the aesthetic
quality of  aquatic  situations by  adding animation and a
fascinating array  of life  forms to an otherwise  largely  static
scene. Observation of these life forms, whether for photo-
graphic, educational  nature study,  or purely recreational
purposes,  is  an  aesthetically enriching  experience.  The
economic importance and popularity of recreation involving
the harvest offish, shellfish, waterfowl, and water-dependent
furbearers  have been discussed earlier. Water-quality  char-
acteristics recommended for the  well-being of aquatic life
and associated wildlife  are  discussed in detail in  Sections
III and IV on Freshwater  and Marine Aquatic Life and

Maintenance of Habitat
  Pressures placed  on the aquatic environment by the in-
creasing human  population are  of major concern.  They
often lead  at  least to disruption and occasionally to de-
struction of related life-support systems  of desired species.
Examples of this are the complete elimination of aquatic
ecosystems by the filling of marshes  or shallow waters for
commercial, residential,  or industrial developments, or the
sometimes  chronic, sometimes partial, and sometimes total
destruction of aquatic   communities by society's  wastes.
Effects of cultural encroachment are often insidious rather
than spectacular. Aesthetic values are gradually reduced,
as is recruitment of water-associated wildlife populations.
  Maintenance of life-support systems for aquatic life and
water-related wildlife requires adequately oxygenated water,
virtual freedom from damaging materials  and toxicants,
and the  preservation of a general habitat for routine ac-
tivities, plus the critical habitat necessary for reproduction,
nursery areas, food production, and protection from preda-
tors. Each species has its specific life-support requirements
that, if not adequately met, lead to depauperate populations
or complete species elimination. The life-support  systems
essential  to the survival of desired aquatic life and  wildlife
are required for man to enjoy the full scope of water-related
recreational and aesthetic benefits.
  Man is often  in direct competition for a given  habitat
with many  species of aquatic life and wildlife. In  some
areas, the use of specific  waters for recreation based on
aquatic life and wildlife may be undesirable for a number of
reasons, including potential conflicts with other recreational
activities. Limitations on  the use of surface water capable
of providing recreational wildlife observation, hunting, and
fishing under practical management should not be imposed
by unsuitable  water quality.

Variety of Aquatic Life
  Natural surface waters support  a  variety of aquatic life,
and each species is of interest or importance  to man for
various reasons.  While water-based recreation often evokes
thoughts of fishing, there are a number of other important
recreational activities, such as skin diving, shell and insect
collecting, and  photography, that also benefit from the
complex  interrelationships that  produce fish. A variety of
aquatic life  is intrinsic  to our aesthetic enjoyment of the
environment.  Urban waterbodies may be  the  only  local
sites where  residents can still  conveniently  observe and
contemplate a complete web of life, from primary producers
through  predators.
  Reduction in the  variety of aquatic life has long been
widely used as an indication of water-quality degradation.
The degree of reduction in species diversity often indicates
the intensity  of  pollution because,  as a  general  rule, as
pollution increases, fewer  species can tolerate the environ-
ment.  Determining  the extent of reduction can  be ac-
complished by studying the entire ecosystem; but the phe-
nomenon is also reflected in the  community structure  of
subcomponents, e.g., bottom animals, plankton, attached
algae, or fish. Keup et al. (1967)236 compiled excerpts  of
early studies of this type. Mackenthun (1969)237 presented
numerous case studies dealing with  different types of pol-
lutants,  and Wilhm and  Dorris  (1968)238  have reviewed
recent efforts to express diversity indices mathematically.
  While  most water quality recommendations in  Sections
III and  IV on  Freshwater and Marine Aquatic Life and
Wildlife  are designed for  specific and known hazards, it is

Z§/Section I—Recreation and Aesthetics
impossible  to make recommendations which will protect
all organisms from all hazards, including manipulation of
the physical environment. In  similar habitats and under
similar environmental conditions, a reduction in variety of
aquatic life (species diversity)  can be symptomatic  of an
ecosystem's  declining health and signal deterioration  of
recreational or other beneficial uses. In addition to mainte-
nance of aquatic community structures, special protective
consideration should  be given  sport, commercial,  and en-
dangered species of aquatic life and wildlife.
  To maintain and protect aesthetic values  and
recreational activities associated with aquatic life
and wildlife,  it  is recommended  that the water
quality recommendations  in the  Freshwater  and
Marine Aquatic Life and Wildlife reports (Sections
III and IV) be applied.
  Since changes in species diversity are often as-
sociated with changes in water quality and signal
probable  changes  in recreational  and  aesthetic
values, it is recommended that changes in  species
diversity be employed  as indications that corrective
action may be necessary. (See Section III on Fresh-
water Aquatic  Life and Wildlife,  and  Appendix
II-B  on   Community  Structure   and  Diversity

  Shellfish* are a renewable, manageable natural  resource
of considerable economic  importance, and the water quality
essential to their protection  in  estuarine  growing  areas  is
discussed by the panel on Marine Aquatic Life and Wildlife
(Section IV). However, the impact of shellfish as related to
recreational and aesthetic enjoyment is also important, al-
though difficult to estimate  in  terms of time and money.
Furthermore, because contaminated shellfish may be har-
vested  by the public, it is necessary to protect these people
and others who may eat the  unsafe catch.
  Clams and oysters are obtained  from intertidal  areas,
and these marine species have an unusual ability to  act as
disease vectors and to accumulate hazardous materials from
the water. As more people are able to seek them in a sports
fishery, the problems  of public  health  related  to  these
animals intensify.
  Because  the intent here is to protect  persons engaged in
recreational shellfishing, consideration  will be  given  to
numerous factors which  affect shellfish and their  growing
areas.  These include  bacteriological quality,  pesticides,
marine biotoxins, trace metals, and radionuclides.
  Recreational shellfishing should be limited to waters of
quality that allow harvesting for direct marketing. Epi-
  * As used here, the term "shellfish" is limited to clams, oysters, arid
demiological  evidence  accumulated  through 46  years
operation under  the federal-state cooperative Natior
Shellfish Sanitation Program (NSSP) demonstrated reaso
able safety in taking shellfish from approved growing are;
  The water quality criteria for determining an "approv
growing area" are the basis of the standards given in t
National Shellfish Sanitation  Program  Manual of Op<
ations, Part 1, Sanitation of Shellfish Growing Areas (PHS Pi
No. 33, 1965).261 The growing area may be designated
"approved" when:

  (a) the sanitary survey indicates that pathogenic mici
organisms, radionuclides, or toxic wastes do not reach t
area in  dangerous concentrations; and
  (b) potentially dangerous concentrations are verified
laboratory findings whenever the sanitary survey indica
the need.

Bacteriological Quality
  Clams and oysters, which are capable of concentrati
bacteria and viruses, are among the  few  animals eat
alive and raw by man. For these reasons, the consumpti
of raw shellfish harvested from unclean  or polluted watt
is  dangerous. Polluted water,  especially  that receivi
domestic sewage, may contain high numbers of bactei
normally carried in  the feces  of man and  other  anima
Although these bacteria may  not themselves be harmf
the danger exists that pathogenic bacteria and viruses m
also be  present (Lumsden  et  al. 1925,250 Old and G
1946,257  Mason  and  McLean 1962,251 Mosley 1964a,
1964b;255 Koff et al.  19G7).248 Shellfish are capable
pumping prodigious quantities of water in their  feedi
and concentrating the suspended bacteria and viruses. T
rate of  feeding in  shellfish is temperature-dependent, w
the highest  concentrating and feeding rate  occurring
warm water above 50 F and almost no feeding occurri
when the water temperatures approach 32 F. Therefo
shellfish meat in  the  winter  months  will have  a lov
bacterial concentration than in the summer months (G
bard  et al.,  1942) ,246  The  National Shellfish Sanitati
Program determines the bacteriological quality of comm
cial shellfish harvesting areas in the following manner:

    • examinations are conducted in accordance with 1
       recommended  procedures of  the American  Pul:
       Health Association for the examination of seawa
       and shellfish:
    • there must  be no direct discharges of inadequate
       treated sewage;
    • samples of water for bacteriological examination ;
       collected  under those conditions of time and  t
       which produce maximum concentrations of bacter
    • the coliform median most probable number (MP
       of the  water does not exceed 70 per 100 ml, and i
       more  than  10 per cent of the samples ordinal
       exceed an MPN of 230 per 100  ml  for a five-tu

                                                                Water Quality Considerations for Specialized Recreation/37
       decimal dilution test (or 330 per 100 ml for a three-
       tube decimal dilution test) in those portions of the
       area most probably exposed to fecal contamination
       during the more unfavorable hydrographic and pol-
       lution conditions; and
     • the reliability of nearby waste treatment plants is
       considered before areas for direct harvesting  are

   Recreational harvesting of shellfish should  be
limited  to areas  where water quality meets  the
National Shellfish Sanitation Program Standards
for approved growing areas.

   Pesticides reach estuarine waters from  many  sources in-
cluding sewage and industrial waste discharge, runoff from
land used for  agriculture and forestry, and chemicals used
to control aquatic vegetation and  shellfish predators. Once
pesticides are  in the marine environment, they are rapidly
accumulated by shellfish, sometimes to toxic concentrations.
Organochlorine compounds are usually the most toxic and
frequently have a deleterious effect at concentrations near
0.1 /ig/1  in the  ambient  water  (Butler  1966b).240 Lowe
(1965)249 observed that DDT at a  concentration of 0.5 ng/l
in water was fatal to juvenile blue crabs  (Callmectes sapidus)
in a few days.
   The biological magnification of persistent pesticides by
mollusks  in the  marine environment may be  very pro-
nounced. Butler  (1966a)239 observed  that DDT may be
concentrated to a level 25,000 times that found in  sur-
rounding sea water within 10 days. In some instances,  de-
pending upon water temperature, duration of exposure, and
concentration  of DDT in the surrounding water, biological
magnification  may be 70,000 times (Butler 1966b).240 Some
shellfish  species, particularly blue mussel (Mytilus edulis),
appear to have a higher concentration  factor than other
species (Modin 1969,253 Foehrenbach  1972).245
   In  1966, a nationwide surveillance system was initiated
by the  U.S. Bureau  of Commercial  Fisheries to monitor
permanent mollusk populations and determine  the extent
of pesticide pollution in North American estuaries. Butler
(1969)241 reported that sampling during the first three years
did not indicate any consistent  trends in estuarine pesticide
pollution. Distinct seasonal and geographical differences in
pollution levels were  apparent. Pesticides most  commonly
detected in order of frequency were DDT (including its
metabolites), endrin,  toxaphene,  and mirex. The amounts
detected in North  American estuaries varied.   In Wash-
ington,  less than  3  per cent of the sampled shellfish were
contaminated  with  DDT. Residues were always less than
0.05 mg/1. On the Atlantic Coast, DDT  residues in oysters
varied from less than 0.05 mg/1 in marine estuaries to less
than  0.5 mg/1 in others. In  a  monitoring program  for
TABLE 1-4—Recommended Guidelines for Pesticide Levels
                       in Shellfish
Heptachlor Eporide° 	
Lmdam 	 . 	
Concentration in shellfish
(ppm-dramed weight)
 «It is recommended that if the combined values obtained for Aldrin, Dieldrin, Endrin, Heptachlor, and Heptachlor
Epoxide exceed 0.20 ppm, such values be considered as"alert" levels which indicate the need for increased samp'inf
until results indicate the levels are receding. It it further recommended that when the combined values tor the
above five pesticides reach the 0.25 ppm level, the areas be closed until it can be demonstrated that the levels an
 U.S. Department of Health, Education and Welfare, Public Health Service 19!8.-3
chlorinated hydrocarbon  pesticides in estuarine organisms
in marine waters of Long Island, New York, Foehrenbach
(1972)245 found that  residues of DDT,  ODD, DDE, and
dieldrin in shellfish were well within the proposed limits of
the 6th National Shellfish Sanitation Workshop  (1968)262
(see Table 1-4).  For most cases, the levels detected were
10- to 20-fold less than the recommendations for DDT and
its  metabolites, and in many  instances concentrations  in
the shellfish were lower by a factor of 100.
  Although pesticide levels in many estuaries in the United
States are low, the marked ability of shellfish to concentrate
pesticides indicates that the levels approached in  waters
may be considered significant in certain isolated instances
(Environmental Protection Agency 1971).244

  Concentrations of pesticides in fresh and marine
waters that provide an adequate level of protection
to  shellfish are recommended in  the Freshwater
and  Marine Aquatic  Life  and  Wildlife Reports,
Sections III and IV. Levels that protect the human
consumer of shellfish should be  based on pesticide
concentrations in  the edible portion of the  shell-
fish. Recommended human health guidelines for
pesticide concentrations in shellfish have been sug-
gested by  the  6th National  Shellfish  Sanitation
Workshop  (1968)262,  Table  1-4.  They  are  recom-
mended here as interim guidelines.

Marine Biotoxins
  Paralytic poisoning due to the ingestion of toxic shellfish,
while not  a  major public health problem,  is a  cause  of
concern to health officials because  of its extreme toxicity,
and because  there is no known antidote. Up to 1962, more

38/'Section I—Recreation and Aesthetics
than 957 cases of paralytic shellfish poisoning are known
to have occurred, resulting in at least 222 deaths in the
United States (Halstead 1965).24
  Paralytic shellfish  poison is a non-protein, acid-stable,
alkali-labile biotoxin nearly 10,000 times as lethal as sodium
cyanide. The original source  of the poison is a species of
unicellular  marine dinoflagellates, genus Gonyaulax. Gony-
aulax cantenella,  perhaps the best known of the toxic dino-
flagellates, is found on the Pacific Coast. Gonyaulax tamarensis
is the causative organism  of paralytic shellfish  poison on
the Atlantic Coast of Canada and the northern United
States. Other dinoflagellate species have  been identified in
outbreaks of paralytic shellfish poisoning outside the United
States (Halstead 1965).247
  Mollusks and other seashore animals may become poison-
ous if they consume  toxic planktonic algae. Mussels and
clams are the  principal species  of edible mollusks that
reach dangerous levels of toxicity. Although oysters can
also become toxic, their apparent uptake of toxin is usually
lower; and they are  usually reared in areas free  of toxin
(Dupuy and Sparks 1968).243
  The level of toxicity of shellfish is  proportional to the
number and  poison  content of Gonyaulax ingested. When
large numbers of Gonyaulax are present in the water, shellfish
toxicity may rise rapidly to dangerous levels (Prakash and
Medcof 1962).268 The extent  of algal growth depends on
the combination of nutrients, salinity, sunlight, and temper-
ature. Massive blooms of algae are most likely to occur in
the warm summer months. In the absence of toxic  algae,
the poison that had been stored in  the shellfish is eliminated
by a purging action  over a period of time (Sommer and
Meyer 1937).260
  Although Gonyaulax only blooms in the warmer months,
shellfish are not necessarily free from  toxin during the rest
of the year, as there is great variation  in the rates of uptake
and elimination of the poison among  the various species of
mollusks. It is possible for certain species to remain toxic
for a long period of time.  Butter clams, for example, store
the toxin for a considerable length of time, especially under
cold  climatic  conditions  (Chambers  and  Magnusson
  Cooking  by boiling, steaming,  or  pan frying does not
remove the danger of intoxication, although it does reduce
the original poison content of the raw meat to some extent.
Pan frying  seems to  be more effective than other cooking
methods  in reducing  toxicity  probably  because higher
temperatures are involved. If the water in which shellfish
have been  boiled is  discarded, most of the toxin will  be
removed (McFarren  et al. 1965).252
  A chemical method for the quantitative determination of
the poison  has been  devised,  but the most generally used
laboratory technique for determining the toxicity of shellfish
is a bioassay using mice. The  toxin extracted from shellfish
is injected into test mice and the length of time elapsii
from injection of the mice  to the time of their death c;
be correlated with the  amount of poison the shellfish co
tain. The quantity of paralytic shellfish poison produci
death is measured in mouse units.

  Since there is no analytical measurement for tl
biotoxin in water, shellfish should not be harvest*
from any areas even if "approved" where analys
indicates a Gonyaulax shellfish toxin poison coi
tent  of  80  micrograms  or  higher,  or  where
Ciguateria-like toxin reaches 20 mouse units  p
100 grams of the edible  portions of raw  shellfii

Trace Metals
  The hazard to humans oi" consuming shellfish containii
toxic  trace metals has been  dramatized by outbreaks
Minimata in  Japan. Pringle et al. (1968)259 noted that t
capacity  of shellfish to concentrate  in vivo some  metals
levels many hundred times greater than those in the e
vironment means that  moliusks exposed to pollution m;
contain  quantities sufficient  to produce toxicities in t
human consumer.

  Concentrations  of metals in fresh and marii
waters that provide  an adequate level of protectic
to shellfish  are recommended in  the Freshwat
and Marine Aquatic Life and Wildlife Section
HI and IV. Recommendations to protect  the hi
man consumer of shellfish should be based on trac
metal content  of the edible portions of the she!
fish,  but necessary  data  to support  such recon
mendations are not currently available.

  Radioactive wastes  entering water present a potent
hazard to humans who consume shellfish growing in su
water. Even though radioactive material may be discharg
into shellfish growing  waters at levels  not exceeding t
applicable standards, it  is  possible that accumulation
radionuclides  in  the aquatic food  chain may  make t
organisms used as food unsafe. The  radionuclides Zn66 a
P32 (National Academy of  Sciences 1957)256 are  known
be concentrated  in shellfish  by five orders of magnitu
(105). Therefore, consideration must be given to radioacti
fallout or discharges of wastes from nuclear reactors ai
industry into shellfish growing areas. For further  discussv
of this subject see  Section IV,  Marine Aquatic Life ai
Wildlife, p. 270.


  There are still numerous watersheds in the United States
that are remote from population centers. Almost inaccessible
and apparently free from man's developmental influences,
these watersheds are conducive to mental as well as physical
relaxation in the naturalness of their surroundings. To as-
sure the preservation of such natural beauty, the Wild and
Scenic Rivers Act of 1968  established in part a  national
system of wild and scenic rivers (U.S.  Congress  1968).269
Eight rivers  designated  in the Act in whole or in part
constituted the original components of the system:

  1.  Clearwater, Middle Fork, Idaho
  2.  Eleven Point, Missouri
  3.  Feather, California
  4.  Rio Grande, New Mexico
  5.  Rogue, Oregon
  6.  Saint Croix, Minnesota and Wisconsin
  7.  Salmon, Middle Fork, Idaho
  8.  Wolf, Wisconsin

  All or portions of 27 other rivers were mentioned specifi-
cally in the Act as being worthy of inclusion in the system
if studies to be conducted by several federal agencies showed
their inclusion to be feasible. Certainly there are many more
rivers in the nation worthy of preservation by state and
local agencies (U.S. Department of the Interior, Bureau of
Outdoor Recreation, 1970).270 In Kentucky alone,  it was
found that 500 streams and watersheds,  near  urban areas,
would serve purposes of outdoor recreation in natural  en-
vironments (Dearinger 1968).264
  Characteristically, such wild river areas are: (a) accessible
to man in only  limited degrees; (b) enjoyed  by relatively
few people who  actually go to the site; (c)  visited  by scout
troops or other small groups  rather than by lone indi-
viduals; and (d) productive of primarily intangible,  aesthetic
benefits of real  value though  difficult  to  quantify (U.S.
Outdoor Recreation Resources Review Commission 1962.271
Sonnen et al. 1970267).
  The  quality of natural  streams is generally good, pri-
marily because man's activities leading to waste discharges
are minimal or nonexistent in the area.* However, fecal
coliform concentrations in some natural waters have been
found to be quite high following surface runoff (Betson and
Buckingham unpublished report 1970;273 Kunkle and Meiman
1967266), indicating the possible presence of disease-causing
organisms in these waters. The sources of fecal coliforms in
natural waters are wild  and domestic animals and birds,
as well as  human beings who occasionally visit the  area.
Barton  (1969)263 has also reported that natural areas may
contribute  significant loads of nitrogen, phosphorus,  and
other  nutrients to the  streams  that  drain them.  These
chemicals can  lead to algal blooms and  other naturally
occurring but  aesthetically unpleasant  problems.  Barton
(1969)263 also  points out the paradox  that a significant
contributor to  pollution of natural waters is the  human
being who comes to enjoy the uniquely unpolluted environ-
ment.  In addition to water-quality degradation, man also
contributes over one pound per day of solid wastes or refuse
in campgrounds and wilderness areas, a problem with which
the  Forest  Service  and  other agencies must now  cope
(Spooner 1971).268
   This discussion has concentrated on Wild and Scenic
rivers. However, similar consideration should be given to
the recognition and preservation  of other wild stretches of
ocean  shoreline,  marshes, and unspoiled  islands  in fresh
and salt waters.


   Many large water bodies are located near or in urban and
metropolitan  areas. These waters include major  coastal
estuaries and bays,  portions of the Great Lakes,  and the
largest inland rivers. Characteristically,  these waters serve
a multiplicity of uses and are an economic advantage to the
  * Some of the least mineralized natural waters are those in high
mountain areas fed 6y rainfall or snowmelt running across  stable
rock formations. One such stream on the eastern slope of the Rocky
Mountains has been found to have total dissolved solids concentra-
tions often below 50 mg/1, coliform  organism concentrations of 0
to 300/ml, and turbidities of less than 1 unit (Kunkle and Meiman

40/'Section I—Recreation and Aesthetics
region and to the nation  as a whole. In addition to pro-
viding water supplies, they have pronounced effects on local
weather  and make possible valuable  aesthetic and recre-
ational pleasures, ranging from simple viewing to fishing
and boating.
  Large  urban  waterways,  because of their location in
densely populated areas,  are  heavily used  commercially
and are also in great demand for recreational and  aesthetic
purposes. Consequently, although swimming and other con-
tact activities cannot always be provided in all such waters,
quality levels supportive of these activities should be en-
  Water  flow in the urban stream tends to be variable and
subject to higher and more frequent flood flows than under
"natural  conditions,"  because  storm water  runoff from
buildings and hard-surfaced areas is so complete and rapid.
The impaired quality of the water may be due to storm water
runoff, upstream soil erosion, or sewage discharges and low
base flow. Whitman (1968)272 surveyed the sources of pol-
lution  in the  urban streams in Baltimore and Washington
and reported that sewer malfunctions, many of which might
be eliminated, were the largest causes of poor water quality.
In large  metropolitan  areas with either separate  or com-
bined sewer systems, pollution of the urban waterway can
be expected during heavy rainstorms when the streams may
contain coliform concentrations in the millions per 100 ml.
In addition, these flood waters flow with treacherous swift-
ness and  are filled with mud and debris.
  Small  urban streams are even more numerous. Although
these may  have only intermittent flow, they have the ca-
pacity to provide considerable  opportunities for  a variety
of water-related recreation activities. Unfortunately, these
in-city streams are more often eyesores than they are com-
munity treasures.  Trash,  litter, and  rubble are  dumped
along  their banks, vegetation  is  removed,  channels are
straightened and concrete stream beds are constructed or
even roofed over completely to form covered sewers.
  This abuse and destruction of a  potential economic and
social resource  need not occur. The urban stream can be
made the focal point of a  recreation-related complex. The
needs of the cities are  many, and  not the least of them is
the creation of a visually attractive urban environment in
which the role of water is crucial.
  The reclamation of downtown sections of the San Antonio
River  in the commercial  heart of San Antonio,  Texas,  is
perhaps  the best known and most encouraging example of
the scenic and cultural potential of America's urban streams
(Gunn et al. 1971).266 From a modest beginning with WPA
labor in  the mid-1930's, the restoration of about a  one-mile
portion of the river threading  its way through the central
business  district has resulted in the creation of the Paseo
Del  Rio, or River  Walk. Depressed below the level of
adjacent streets, heavily landscaped with native and tropical
vegetation, the river is bordered with pleasant promenades
along  which  diners relax  in outdoor cafes. Fountains and
waterfalls add to the visual attractiveness, and open barg
carry groups of tourists or water-borne diners to histoi
buildings, restaurants,  clubs, and a  River  Theater.  Mo
popular with both local residents and tourists each year, t
River Walk has proved to be a significant  social and ec
nomic development, attracting commercial enterprises
a previously blighted  and unattractive area. The  Riv
Walk is widely visited and studied as a prototype for urb;
river  reclamation,  and it demonstrates that urban  rive
can serve as the environmental skeleton on which an enti
community amenity of major proportions can be built.


  Between the remote  and seldom used waters of Amerii
at one extreme and the urban waterways at the other a
many unique water recreation spots  that are visited ai
enjoyed by  large numbers of tourists each year. Amoi
these  are Old Faithful, Crater  Lake,  The Everglades, tl
Colorado  River-Grand Canyon National Park,  and La]
Tahoe.  These ecologically or geologically  unique wate
are  normally maintained in very nearly their natural coi
ditions, but  access  to  them  is freer  and  their  monetai
value is greater than  that of the wild rivers.  To man
however, their aesthetic value will always be greater the
their monetary value. It is obviously impossible to establi:
nationally  applicable  quality recommendations  for su<
waters. (It would be ludicrous,  for example, to expect O
Faithful to be as cool  as Crater Lake, or The Everglad
as clear as Lake Tahoe.) Nonetheless, responsible agenci
should establish recommendations for each  of these wate
that will protect and preserve their unique values.
  Municipal raw water supply  reservoirs  are often  a  p
tential source of recreation and  aesthetic enjoyment. Pei
odic review of the recreational restrictions to protect  wat
quality in such reservoirs could result in provision of ai
ditional recreational and aesthetic opportunities.  (See al
the  general Introduction, p. 3—4 regarding preservatic
of aquatic sites of scientific value.)

  To preserve or  enhance  recreational and  aei
thetic values:
• water quality supportive  of general recreation
  adequate to provide tor the intended uses of wil
  and scenic rivers;
• water quality supportive  of general recreation
  adequate to protect or enhance  uses of urba
  streams,  provided  that  economics, flow  cor
  ditions,  and  safety  considerations  make thes
  activities feasible;
• special  criteria are  necessary to  protect  th
  nation's unique recreational waters with regar
  to  their  particular physical,  chemical,  or  bic
  logical properties.

                                                    LITERATURE  CITED

1 The Boating Industry (1971), The boating business, 1970. 34(l):39-62.
2Brightbill,  C. K. (1961), Man and leisure (Prentice Hall, Englewood
     Cliffs, New Jersey), p. 9.
3 Butler,  G. D.  (1959),  Introduction  to  community recreation,  3rd ed.
     (McGraw-Hill Book Co., Inc., New York), p. 10.
4 Doell, C.  E.  (1963),  Elements of park and recreation  administration
     (Burgess Publishing Co., Minneapolis), p. 3.
6 Lehman, H. C.  (1965), Recreation, in  Encyclopedia  Britannica 19:
6 Ragatz,  R. L.  (1971),  Market potential for seasonal homes (Cornell
     University, Ithaca, New York).
'Slater, D.  W. (1972), Review of the 1970 national survey. Trans.
     Amer. Fish. Soc. 101(1):163-167.
8Stroud, R. H. and R. G. Martin (1968), Fish conservation highlights,
     W63-W67 (Sport Fishing  Institute, Washington, D.C.), pp. 25,
9 U.S. Congress (1968), Wild and Scenic Rivers Act, Public Law 90-542,
     S. 119,  12 p.
10 U.S. Congress  (1965),  Federal Water  Project Recreation Act, Public
     Law 89-72,  79S., July 9, 1965, 213 p.
"U.S. Congress  (1968),  Estuary Protection Act,  Public Law 90-454,
     82S.625, August 3, 1968.
12 U.S. Department of the Interior, Press releases, October 30,  1961
     and November 10, 1961.
13 U.S. Department  of the Interior.  Bureau of Outdoor Recreation
     (1967), Outdoor recreation  trends  (Government  Printing  Office,
     Washington, D.C.), 24  p.
14 U.S. Department  of the Interior,  Bureau of Outdoor Recreation
     (1971), Communications from the  division of nationwide plan-

References Cited
16 Bureau  of Outdoor Recreation, personal communication 1971.
16 Churchill, M.  A.  (1972), personal  communication  Water  Quality
     Branch, Division of Environmental Research and Development,
     Tennessee Valley Authority, Chattanooga, Tennessee.
17 Slater, D. W.  (1971),  personal  communication,  Division of River
     Basin Studies, Bureau of Sport Fisheries and Wildlife, U.S. De-
     partment of the Interior,  Washington, D.C.
18 Stout, N.  (1971),  personal communication Division of Research  and
     Education, Bureau of Outdoor Recreation, U.S. Department of
     the Interior, Washington, D.C.


19 Forges, R. et al. (1952), Lower Missouri river basin water pollution
     investigation,  a cooperative  state-federal report,   water pollu-
     tion series 47. Federal  Security Agency, Public Health Service
     Publication 269:27.
20 Ashton, P. G. and M. Chrbb (1971), A preliminary study for de-
    termining  boating  carrying  capacity  standards. Paper given at
    the Seventh American  Water Resources Conference, Washington, D.C.
21 Chubb, M. (1969), Proceedings of the national Jorum on recreation stan-
    dards, National Recreation and Parks Association, held at Kansas
    City, Missouri.
22 Chubb, M. and P. G. Ashton  (1969), Park and recreation standards
    research: the creation of environmental quality controls for  recreation, a
    report to the National Recreation and Parks Association, Tech-
    nical Report  No.  5,  Recreation Research  and Planning  Unit
    (Michigan State University, East Lansing, Michigan), pp. 12—27.
23Cowgill,  P. (1971), "Too many people on the  Colorado River,"
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232 English, J. N., E. W. Surber, and G. N. McDermott (1963), P(
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243Dupuy, J. L. and A. K. Sparks (1968), Gonyaulax washingtonesis,
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247 Halstead,  B. W. (1965), Invertebrates, vol. 1 of Poisonous and vet
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261 Mason, J. A.  and  W. R.  McLean (1962), Infectious  hepatitis
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264 Mosely, J. W.  (1964a), A.  Clam-associated  infectious hepatitis—
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267 Old, H.  N.  and S. L. Gill  (1946), A typhoid  fever epidemic
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                      Section  II  PUBLIC WATER  SUPPLIES
                                   TABLE OF  CONTENTS

         Conclusion. . .








                                               OIL AND GREASE	













  Modern water management techniques and a wide va-
riety of available water treatment processes make possible
the use of raw water of almost any quality  to produce an
acceptable public water supply. For this reason it is both
possible and desirable to  consider water management al-
ternatives and treatment procedures in making recommen-
dations on  the  quality of raw water  needed for public
supplies.  Furthermore, these recommendations  must be
consistent with  the  effort and money  it  is reasonable to
expect an individual, company, or municipality to expend
to produce a potable water supply. Denning a reasonable
effort including  treatment processes involves consideration
of present water quality, the degree of improvement in raw
water that is attainable within the bounds of natural con-
trols on water quality, and the help that can be expected
from society in  cleaning up  its waters. In evaluating the
basis for the recommendations in this  Section,  the  Panel
has left water  management  alternatives open  wherever
possible, but  it has  made certain arbitrary assumptions
about the treatment process.
  The federal Drinking Water Standards for treated water
for  public supply (U.S. Department of Health,  Education
and Welfare, Public Health Service 1962, hereafter referred
to as  PHS 19626)* are under review and revision, but the
final standards were not available to the  Panel on Public
Water Supplies  at the time of publication of this Report.
The Panel did, however, have access to the data, references,
and rationale being considered in the revision of Drinking
Water Standards, and these have had a major influence on
recommendations in this report

  Surface  water supplies  characteristically contain  sus-
pended sediment in varying  amounts  and  are  subject to
bacterial and viral contamination. Therefore, it is assumed
that the following  defined treatment,  and  no more,  will
be  given  raw surface water  in a properly operated plant
prior to human  consumption.
   1.  coagulation (less than  about 50 milligrams per  liter
  * Citations are listed at the end of the Section. They can be located
alphabetically within subtopics or by their superior numbers which
run consecutively across subtopics for the entire Section.
(mg/1) alum, ferric sulfate, or copperas with alkali or acl
addition as necessary but without  coagulant aids or acti
vated carbon);
  2.  sedimentation (6 hours or less);
  3.  rapid sand filtration (three gallons  per square  foe
per minute or more);
  4.  disinfection  with  chlorine (without consideration  t
concentration or form of chlorine residual).

  The panel recognizes  that  on the one hand some  ra\
surface waters will meet federal Drinking Water Standard
with no treatment other than  disinfection,  and that on th
other hand almost  any water, including sea water  arn
grossly polluted fresh water,  can be made  potable for
price by available treatment processes  already developec
However,  the  defined treatment outlined above  is con
sidered reasonable in view of both the existing and generall
attainable quality of raw surface waters, and  the protectio
made imperative by  the current practice of using stream
to transport and degrade waste's. Assumption of the definei
treatment process  throughout this Section is not meant  I:
deny the availability, need, or practicality of other wate
treatment processes.
   Unlike  surface waters,  ground waters characteristicall
contain little  or no  suspended sediment and are largel
free of and easily  protected from bacterial and viral con
tamination. (See Ground Water Characteristics  below for sig
nificant exceptions.) Therefore, no  defined treatment is as
sumed for raw ground water designated for use as a publi
supply,  although here again this does not deny the avail
ability,  need,  or practicality of treatment. Ground water
should meet current federal Drinking Water  Standards  h
regard  to  bacteriological  characteristics and content  o
toxic substances,  thus  permitting  an  acceptable  publii
water supply to be produced with no treatment, providing
natural water  quality is adequate  in other  respects. Th<
recommendations  in this section based on consideration
other than bacterial content and toxicity apply to grounc
waters as well as surface waters unless otherwise specified.


   The Panel has defined water quality recommendation:
as those limits  of characteristics and concentrations of sub-

                                                                                                      Introduction /'51
stances in raw waters that will allow the production of a
safe, clear, potable, aesthetically pleasing  and acceptable
public  water supply  after  treatment.  In making these
recommendations,  the  Panel recognized that most of the
surface water treatment plants providing water for domestic
use in the United States are relatively small,  do not have
sophisticated technical controls, and are operated by indi-
viduals whose training in modern methods varies widely.
The recommendations assume the  use of the  treatment
process defined above but no more.
  Regional variations  in natural water quality make  it
necessary to apply understanding and discretion when evalu-
ating raw water quality in terms of the recommendations.
Wherever water  zoned for public supply  fail to  meet the
recommendations in all respects, the recommendations can
be considered the minimum goal  toward which to work in
upgrading water quality. In  some  instances the natural
presence of certain constituents in raw water  sources may
make  the  attainment  of recommended levels impractical
or even impossible. When such constituents affect human
health, the water cannot be used for public supply unless
the constituent can be brought to Drinking Water Standards
levels through a specially designed treatment process prior
to distribution to consumers. Where  health is not a factor,
the natural level  of the constituent prior to man-made ad-
ditions can be considered a reasonable target toward which
to work, although determination of "natural quality" may
require considerable effort, expense, and time.
  The recommendations in this report should by no means
be construed as latitude to add substances to waters where
the existing quality is  superior  to that called for in the
recommendations.  Degradation  of raw water sources of
quality higher than that specified should be minimized in
order to preserve operational safety factors and economics
of treatment.
  The Panel considered factors of safety for each of the
toxic substances discussed,  but numerical factors of safety
have been employed only where data are  available on the
known  no-effect  level  or the minimum effect level of the
substances on humans. These factors were selected on the
basis of the degree of hazard and the  fraction of daily
intake of each substance that can reasonably be assigned
to water.
  The recommendations should be regarded  as  guides in
the control of health hazards and not as fine lines between
safe and dangerous concentrations. The amount and length
of time by which values in  the recommendations may be
exceeded  without injury to health depends upon the nature
of the contaminant, whether high concentrations even for
short periods produce acute poisoning, whether  the effects
are cumulative, how frequently high concentrations occur,
and how long they last. All these factors must be considered
in deciding whether a hazardous situation exists.
  Although some of the  toxic substances considered are
known to be associated  with suspended solids in raw surface
waters and might thus be removed to some extent by the
defined treatment  process, the degree  of removal of the
various dissolved toxic substances is not generally known;
and even if known, it could not be assured under present
treatment  practices. Therefore, in the interest of safety, it
has usually been assumed here that there is no removal of
toxic substances as a result of the defined treatment process.
   Substances not evaluated in this Section are  not neces-
sarily innocuous in public water supply sources. It would be
impractical to prepare  a compendium of all toxic,  dele-
terious, or otherwise unwelcome agents, both organic and
inorganic,  that may enter a surface water supply. In specific
locations it may become necessary to consider  substances
not included  in this  section, particularly  where local pol-
lution suggests that a substance may have an effect on the
beneficial use of water for public supplies.
   In  summary:  the  recommendations in this Section for raw
water quality for public supplies  are intended to assure that the
water will be potable—for surface  water, with the defined treatment
process; for  ground water, with no treatment. For waters zoned for
public supply but not meeting  the  recommendations in  all respects,
the recommendations can be considered a minimum  target toward
which efforts at upgrading  the quality should be directed. In some
instances  the natural  quality  of  raw water may make  meeting
certain recommendations impractical or even impossible. For con-
stituents for which this is the case,  and where health is not a factor,
the natural  quality of  the water  can  be  considered  a reasonable
target toward which to work,  although  determination  of "natural
quality" may require considerable effort, expense, and time. Wherever
water quality is found superior to  that described in the recommen-
dations, efforts should be made to minimize its degradation.

   The importance of establishing an effective sampling and
monitoring program and the difficulties involved cannot be
overemphasized. A  representative  sample of  the  water
entering the raw water intake should be obtained. Multiple
sampling,  chronologically and spatially, may be necessary
for an adequate characterization of the raw water body,
particularly for constituents associated with suspended solids
(Great  Britain  Department  of the  Environment 1971;3
Brown et al.  1970;2 Rainwater  and Thatcher I9604). Moni-
toring plans should take into account the results  of sanitary
surveys (U.S. Department of Health,  Education, and Wel-
fare 1969 ;7 American Public Health Association, American
Water Works Association, and Water Pollution Control
Federation 19711 hereafter referred to as Standard Methods
19715)  and the  possibility of  two types of water quality
hazards: (1) the chronic hazard where constituent concen-
trations are near the limit of acceptability much of the time,
and (2) the periodic hazard caused by upstream release of
wastes or accidental spills of hazardous substances into the
stream. Samples for the determination of dissolved con-
stituents only should be passed through a noncontaminat-
ing filter at time of collection.

52/Section II—Public Water Supplies

  The recommendations are based on the use of analytical
methods for raw water analysis as described in Standard
Methods  (1971).5 Other procedures of similar  scientific
acceptability are continuously evolving but  whatever the
analytical procedure used, the panel assumes that it  will
conform to the statistical concepts  of precision, accuracy,
and reporting style discussed in the introduction to Standard
Methods (1971).5 Analytical results should indicate whether
they apply to a filtered or unfiltered sample.


  Development  of water  quality  recommendations  for
ground water  must provide for the significant differences
between surface water  and ground water. Ground water is
generally not  confined in  a  discrete channel.  Its quality
can be measured  in detail only with difficulty and at great
expense. A  thorough  knowledge of the hydrologic char-
acteristics of the ground water body can be obtained only
after extensive study. Movement of ground  water can be
extremely slow so that contamination occurring in one part
of an aquifer ma/ not become evident at a point of with-
drawal for several, tens, hundreds, or  even  thousands of
  Wastes mix differently with ground waters than they do
with surface waters. Where allowance for a mixing zone in
the immediate vicinity of a waste outfall can be provided
for in  surface  water standards under the assumption  that
mixing is complete within a  short distance downstream,
dispersion of waste in a ground water body may  not be
complete for many years. At  the same time, the long re-
tention time will facilitate bacterial or  chemical reactions
with aquifer components that result in removal or decompo-
sition of a pollutant to the point where it no longer degrades
the aquifer. Because these reactions are imperfectly known
and cannot be predicted at the present time,  it is necessary
to monitor the movement of waste in a ground water body
from the point of introduction outward. Bodies of ground
water cannot be monitored adequately by sampling at the
point of use.
  Inadvertent or  careless  contamination of fresh ground
water  bodies is occurring today from the  leaching of ac-
cumulated salts from irrigation, animal feed lots, road  salt,
agricultural fertilizers, dumps,  and landfills, or from leakage
of sewer lines in sandy soil, septic tank effluents, petroleum
product pipelines, and chemical waste  lagoons. Another
source of contamination is the upward movement of saline
water in improperly plugged wells and drill holes, or as the
result of excessive withdrawal of ground water. Deep-well
injection causes intentional introduction of wastes into saline
ground water bodies.
  Because of their common use as private water supplies
in rural  areas,  all geologically unconfined  (water-table)
aquifers could be placed in a classification comparable  to
that for raw surface waters used for public water supplies.
Even though not all waters  in these aquifers are suitable
for use without treatment, such classification could be used
to prohibit introduction of wastes into them.  This in turn
would restrict the use of landfills and other surface disposal
practices.  Limited use of the unsaturated zone for disposal
of wastes would still be acceptable, provided that decompo-
sition of organic  wastes and sorption of pollutants  in  the
zone of aeration were essentially complete before the drain
water reached the water table  Bodies  of artesian ground
water in present  use as public and private supplies could
be similarly classified wherever  their natural  source of re-
charge was sufficient to sustain the current yield and quality.
  Disposal of wastes in either of the above types of aquifers
could be expressly forbidden on the basis of  their classifi-
cation as  public  water supplies. Furthermore,  before dis-
posal of wastes to the soil or bedrock adjacent  to aquifers
used or usable  for public supply were permitted, it could
be required that a geologic reconnaissance be made to de-
termine possible effects  on ground water quality.
  Water quality  recommendations for raw ground  waters
to be used for public water supplies are more restrictive
than water quality recommendations for raw surface water
source because of the assumption that no treatment will be
given to the ground waters. The distinction between surface
and  ground waters is therefore necessary for proper appli-
cation of  the recommendations. In certain cases this dis-
tinction is not easily made. For example, collector wells in
shallow river valley alluvium,  wells  tapping  cavernous
limestone,  and certain other types of  shallow  wells may
intercept water only a short  distance away, or after  only a
brief period of travel, from the: point at which it was surface
water. Springs used  as raw water sources present a similar
problem.  Choice of the appropriate water quality recom-
mendations to apply to such raw  water sources should be
based on the individual situation.

   The  purpose  of establishing  water quality recommen-
dations and, subsequently, establishing water quality stand-
ards is to protect the nation's waters from degradation and
to provide a  basis for improvement of their quality. These
actions should not preclude  the use of good water manage-
ment practices. For  example, it  may be  possible to supple-
ment streamflow with ground water pumped from wells, or
to replace ground water removed from an  aquifer with
surface water  through artificial   recharge.  These other
sources of water  may be of lower  quality than the water
originally present,  but  it  should  remain a  management
choice whether this  lower quality is preferable to no water
at all.  In arid parts of the nation,  water  management
practices of this sort have been applied for many years to
partially offset the  effects of "mining" of ground water
(i.e., its  withdrawal faster  than  it can be  recharged

                                                                                                    Introduction /53
  Furthermore,  it is possible,  by merely removing ground
water from the aquifer,  to degrade the quality of that
remaining—by inducing recharge from a surface or ground
water body of lesser quality.  It does not seem reasonable
to forbid the  use  of the  high-quality water that is there
because of this potential degradation. Of what  value is it
if it cannot be used?
  It would appear, then, that "degradation by choice"
might  be  an alternative  under  certain conditions and
within certain limits. This type of degradation is not com-
parable to that resulting from disposal of wastes in the
water body.  It  is  simply the  price  exacted for using the
water.  In the case of mining without  artificial  recharge,
the philosophy involved is the same as that applied  to the
mining  of other nonrenewable  resources such  as  metal
ores or fossil fuels.  Because considerations of recreation and
aesthetics and the maintenance of fish and wildlife are
generally not involved in this kind of management situation,
it is reasonable that water quality standards should provide
for the mining and artificial recharge of bodies of ground
water zoned for public supply. As in any water manage-
ment program, it would be necessary  to  understand the
hydrologic system and to monitor changes induced in the
system by management activities.
  Preservation of water  management choices can be pro-
tected  by water  use classification. Classification of surface
waters has not been based solely  on  the  fact  that those
waters are being used for public supply at the present time.
Presumably it has been  based  on the  decision that the
body of water in  question  should be usable  for  public
supply with  no more  than the routine forms of water
treatment, whether  or  not  it is  presently  in use for that
purpose. Conversely, failure to zone a body of water for
public supply would not necessarily preclude  its use for
that purpose. Selective zoning could thus be used to assure
desirable water management practices.

  Alkalinity is  a measure of the capacity of a water  to
neutralize acids. Anions of weak acids such as bicarbonate,
carbonate, hydroxide, sulfide, bisulfide, silicate, and phos-
phate may contribute to alkalinity. The species composition
of alkalinity  is  a function  of pH,  mineral  composition,
temperature, and ionic strength.
  The predominant chemical system present  in  natural
waters is the carbonate equilibria in which carbonate and
bicarbonate  ions and carbonic  acid  are in  equilibrium
(Standards Methods 1971).8 The bicarbonate ion is usually
more prevalent. A water  may have a low alkalinity but a
relatively high  pH value  or vice versa, so alkalinity alone
may not be of major importance as a measure of water
  The alkalinity of natural waters may have a wide range.
An alkalinity below 30 to 50 mg/1, as CaGOs, may be too
low to react with hydrolyzable coagulants, such as iron or
aluminum salts, and still provide adequate residual alka-
linity to produce a water that is not excessively corrosive.
Alkalinities below 25  mg/1,  as CaCOs, may also lead to
corrosive waters when only chlorination is practiced, since
there would be inadequate buffer capacity to prevent the
pH from dropping appreciably (Weber and Stumm 1963).s
Low  alkalinity waters may  be difficult to  stabilize by
calcium carbonate  saturation which would otherwise pre-
vent corrosion of the metallic parts of the system.
  High alkalinity waters may have a distinctly unpleasant
taste. Alkalinities of natural  waters rarely exceed 400 to
500 mg/1 (as CaCO3).

  No recommendation can be made,  because the
desirable alkalinity for any water is associated with
other constituents such  as pH and hardness. For
treatment  control,  however, it is  desirable that
there be no sudden variations in the alkalinity.

  Ammonia may be a natural constituent of certain ground
waters. In surface waters its concentration is normally 0.1
mg/1 or less as nitrogen. Higher levels are usually indicative
of sewage or industrial contamination (McKee and Wolf
  Ammonia consumes dissolved oxygen as  a result of its
biochemical oxidation to nitrite and  nitrate. Reliance on
the biochemical oxygen  demand  (BOD)  test (Standard
Methods 197133) for  measuring the  efficiency of sewage
treatment and the quality of effluents  has focused attention
principally on the oxygen requirements of carbonaceous
matter.  Ammonia is  therefore a common  constituent of
treated sewage,  and much of  the burden of satisfying the
nitrogenous  oxygen demand has, in general, been  shifted
from  the sewage treatment plant to the receiving  water
(Sawyer and Bradney 1946,32 Ludzack and Ettinger  1962,29
Johnson and Schroepfer  1964,24 Earth et al.  1966,12  Cour-
chaine 1968,18 Barth  and Dean  1970,11'.Holden  1970,22
Earth 1971,10 Great Britain Department of the Environment
1971,21 Mt. Pleasant and Schlickenrieder 197131).
  Ammonia is sometimes corrosive to copper and copper
alloys (LaQue and Copson  1963,26 Butler and Ison 196613);
it is also a potential algal and microbial nutrient in water
distribution  systems (Larson 1939,27 Ingram and Macken-
thun  196323).
  Ammonia has a significant  effect on the  disinfection of
water with chlorine. The reactions of ammonia with chlorine
result in the formation of chloramine  compounds having
markedly less disinfecting  efficiency  than free chlorine.
Ammonia substantially increases  the chlorine demand at
water treatment plants that  practice  free-residual chlori-
nation.  Approximately 10  parts  of chlorine per part of
ammonia nitrogen  are required  to satisfy the  ammonia
chlorine demand (Butterfield et al. 1943,16 Butterfield and
Wattie 1946,16 Butterfield 1948,14 Fair  et al.  1948,19 Kelly
and Sanderson 1958,25 Clarke and Chang 1959,17 Laubusch
197128). It would therefore be desirable to have as low a
level as possible in the raw water.
  However, since ammonia is present in ground water and
in some surface water  supply sources, particularly at  cold
temperatures, and since it can be removed by the defined
treatment process with adequate  chlorination, the cost of
the treatment is the determining factor. In  the previous
edition of Water Quality Criteria  (U.S. Department of the
Interior, Federal  Water Pollution Control Administration
1968,34 hereafter referred to as FWPCA  196820) a permis-
sible level of 0.5 mg/1 nitrogen was proposed. This is not a
sacrosanct number, but it is considered to be tolerable.

  Because ammonia may be indicative of pollution
and because of its significant effect on chlorination,
it is  recommended  that  ammonia nitrogen in
public water supply sources not exceed 0.5 mg/1.

  Arsenic, a metalloid that occurs ubiquitously in nature,
can be both acutely and chronically toxic to man. Although
no form  of arsenic is known to be essential,  arsenic has
been added in small amounts to animal feed as a growth
stimulant. For 1,577 surface water samples collected from
130 sampling points in the United States, 87 samples showed
detectable arsenic  concentrations  of 5  to 336 micrograms
per liter (^g/1) with a mean level of 64 ^g/1 (Kopp 1969).60
  The chemical forms of arsenic consist of trivalent and
pentavalent inorganic and organic compounds. It  is not
known which  forms of arsenic occur  in  drinking water.
Although comb'nations of all forms are possible, it can be
reasonably assumed that the pentavalent inorganic form is
the most prevalent.  Conditions  that favor chemical and
biological oxidation  promote the shift  to  the pentavalent
species; and  conversely,  those  that favor reduction will
shift the equilibrium to the trivalent state.
  Arsenic content in drinking water in  most United  States
supplies ranges from a trace to approximately 0.1  mg/1
(McCabe et al.  1970).52 No adverse health effects have been
reported  from the ingestion of these waters.
  Arsenic has been suspected of being  carcinogenic  (Paris
1820,55 Sommers and McManus 1953,60 Buchanan  1962,38
Frost 1967,46 Trelles et al.  1970,61 Borgono and  Greiber
197236), but substantial evidence from human  experience
and animal studies now supports the position that arsenicals
are not tumorigenic  at levels encountered in  the environ-
ment (Snegireff and  Lombard 1951,68 Baroni et al.  1963,35
Boutwell  1963,37  Hueper and  Payne  1963,47  Pinto  and
Bennett  1963,56 Kanisawa and Schroeder 1967,49 Milner
  Several epidemiological studies  in Taiwan  (Chen and
Wu  1962)39 have reported a correlation between the in-
creased incidence  of hyperkertosis  and skin  cancer with
consumption  of water  containing  more  than 0.3  mg/1
arsenic. A similar problem has been reported in Argentina
(Trelles et al.  1970).61 Dermatological manifestations of
arsenicism were noted in children  of  Antofagasta,  Chile,
who used a water supply containing 0.8 mg/1 arsenic. A
new water supply  was provided, and preliminary data
showed that arsenic  levels in hair decreased (Borgono and
Greiber 1972).36
  Inorganic arsenic  is absorbed readily from the gastro-
intestinal tract, the lungs, arid to a lesser extent from the
skin and becomes distributed throughout the body tissue;
and  fluids  (Sollmann 1957).5!l It is excreted  via urine
feces,  sweat, and the epithelium of the skin (Dupont et al
1942,44 Hunter et  al. 1942,4S Lowry et al. 1942,51 Ducofl
et al. 1948,43 Crema 1955,40 Musil  and Dejmal  1957).5'
During  chronic exposure, arsenic accumulates mainly  ir
bone, muscle, and skin, and to a smaller degree in liver and
kidneys. This accumulation can be  measured by  analysis
of hair  samples. After  cessation  of  continuous exposure,
arsenic  excretion may  last  up to 70 days (DuBois and
Ceiling  1959).42
  In man,  subacute  and chronic arsenic poisoning may be
insidious and pernicious.  In mild chronic poisoning, the
only symptoms present are fatigue and loss of energy. The
following symptoms may be observed in more severe intoxi-
cation;  gastrointestinal catarrh, kidney degeneration, ten-
ency to edema, polyneuritis, liver cirrhosis, bone  marrow
injury, and exfoliate  dermatitis (DiPalma 1965,41 Goodman
and Oilman 1965).46 It has  been claimed that  individuals
become tolerant to arsenic.  However,  this apparent effect
is probably due to the ingestion of the relatively insoluble,
coarse powder, since no true tolerance has been  demon-
strated (DuBois and  Ceiling 1959).42
  The total intake of arsenic from food averages approxi-
mately 900 /ng/day  (Schroeder and  Balassa 1966).57 At  a
concentration of 0.1  mg/1  and an average intake of 2 liters
of water per day, the intake Jfrom water would  not exceed
200 fig/day,  or approximately  18 per cent of the total
ingested arsenic.

  Because of adverse physiological effects on hu-
mans and because there is inadequate information
on the effectiveness of the denned treatment proc-
ess in removing arsenic, it is  recommended that
public water supply sources contain no more than
0.1 mg/1 total arsenic.

  Procedures for the detection of disease-causing bacteria,
viruses, protozoa, worms, and  fungi  are  complex, time-
consuming,  and in need of further refinement to increase
the levels of sensitivity and selectivity. Therefore, an indirect
approach  to microbial hazard measurement is required.
  Coliform bacteria have been used as indicators of sanitary
quality in water since 1880 when Escherica coli (E. coif)  and
similar gram negative bacteria  were  shown to be  normal
inhabitants of fecal discharges. Although the total coliform
group  as  presently recognized  in  the Drinking Water
Standards includes organisms  known to vary in  charac-
teristics, the total coliform concept merits consideration as
an indicator of sanitary significance, because the organisms
are normally  present in  large  numbers in the  intestinal
tracts of humans and other warm-blooded animals.
  Numerous stream pollution surveys over the years have
used the total coliform measurement as an index of fecal con-
tamination.  However, occasional poor correlations  to sani-
tary  significance result  from the inclusion of some strains
in the total coliform group that have a wide distribution in
the environment and are  not  specific to fecal material.
Therefore, interpretation of total coliform data from sewage,
polluted water, and unpolluted waters is sometimes difficult
For example,  Enterobacter (Aerobacter) aerogenes and Entero-
bacter cloacae can be found  on  various types of vegetation
(Thomas  and McQuillin  1952,78 Fraser et al.  1956,66
Geldreich et al. 1964,73 Papavassiliou et al. 196776), in  soil
(Frank and Skinner 1941,66 Taylor 1951," Randall 1956,76
Geldreich et al. 1962b72), and in water polluted in the past.
Also included  are plant pathogens (Elrod 1942)62 and other
organisms of uncertain taxonomy whose sanitary significance
is questionable. All of these coliform subgroups may  be
found in sewage and in polluted water.
  A more specific bacterial indicator of warm-blooded ani-
mal  contamination is fecal coliform,  defined as those coli-
form that can ferment lactose at 44.5  C to produce  gas in a
multiple  tube procedure  (U.S. Department  of Interior,
Federal Water Pollution Control Administration 196679
hereafter  referred to as (FWPCA 1966)64 or  acidity in the
membrane  filter procedure (M-FC   medium:  Geldreich
et al. 1965).71 Research showed that  96.14 per cent of the
coliform in human feces was positive by this test (Geldreich
et al. 1962a).70 Examination of the excrement from other
warm-blooded  animals, including livestock,  poultry, cats,
dogs, and rodents indicates that fecal coliform contribute
93.0 per cent of the total coliform population (FWPCA
1966),64 Geldreich et al. 1968).68
  At the present time, the only data available from numer-
ous freshwater stream pollution studies on a  correlation of
pathogen  occurrence with varying levels of fecal  coliform
are for Salmonella (Geldreich 1970,67 Geldreich and Bordner
197169). These  data indicate  a sharp  increase in the fre-
quency of Salmonella detection when fecal coliform  densities
are above 200 per 100 milliliters (ml).  For densities of 1 to
200/100 ml, 41 examinations showed 31.7 per cent positive
detection of Salmonella.  For densities of 201 to  1,000/100 ml,
30 examinations showed 83 per cent positive detection. For
densities of 1,000 to 2,000, 88.5 per cent positive detection
was found in  17  examinations, and  for densities  above
2,000, 97.6  per cent  positive detection was  found in 123
  The  significance is further  illustrated by  a   bacterial
quality study  at  several water plant intakes  along the
Missouri River. When fecal coliform exceeded  2,000 orga-
nisms per 100 ml,  Salmonella, Poliovirus types 2 and 3, and
ECHO virus types 7 and 33 were detected (Environmental
Protection Agency 1971).63 Any occurrence of fecal  coli-
form in water is therefore prime evidence of contamination
by  wastes of some warm-blooded animals, and as  the fecal
coliform densities increase, potential health hazards become
greater and  the  challenge  to water  treatment more de-
  A study of the bacteriological quality of raw water  near
six public intakes along the Ohio River showed that of 18
monthly values with maximum total  coliform  densities in
excess of 10,000 organisms per 100 ml, 12 were not paralleled
by  fecal coliform densities above 2,000 organisms per 100
ml  (ORSANCO  Water  Users Committee  1971).74  The
fecal coliform  portion of these total coliform  populations
ranged from 0.2 to 12 per cent.  Data from the  Missouri
River study showed total coliform densities at water intakes
to be frequently in excess of 20,000 organisms per 100 ml

58/Section II—Public Water Supplies
with concurrent fecal coliform densities above 2,000 (En-
vironmental Protection Agency 1971).63 This indicates less
coliform aftergrowth, but proportionately more recent fecal
  The major limitation to the total coliform index is the
uncertain correlation to the occurrence of pathogenic micro-
organisms.  However, fecal coliform  occurrences in water
reflect the  presence of fecal contamination, which is the
most likely  source for pathogens.
  Total coliform  measurements  may  be used as an  al-
ternative to fecal coliform measurements with the realization
that such data are subject  to a wide  range  of  density
fluctuations of doubtful sanitary significance.
  A well-operated plant  using the  defined treatment to
process raw surface water meeting  the recommendations
below can be expected to meet a value of 1 total coliforn
per 100 ml with proper chlorination practice. When coli
form counts in raw surface water approach the recommen
dations, both pre- and post-chlorination may be requirec
to achieve proper disinfection.


  In light of the  capabilities of the defined treat-
ment  process for raw surface waters and the sta-
tistical correlations mentioned, it is recommendec
that  the  geometric mea.ns of fecal coliform anc
total coliform densities in raw surface water sources
not exceed  2,000/100  ml and  20,000/100 ml,  re-

  Barium (Ba) ingestion can cause serious toxic effects on
the heart, blood vessels, and nerves. Barium enters the body
primarily through air and water, since essentially no food
contains  barium in appreciable amounts.
  The solubility product of barium  sulfate  indicates that
1.3 mg/1 sulfate ion limits the solubility  of  barium to  1.0
mg/1. There is some evidence that barium may be ad-
sorbed by  oxides  or hydroxides of  iron and  manganese
(Ljunggren  1955).83 For the public  water supplies of the
100 largest cities in the  United States, the median barium
concentration  was 0.05 mg/1 with a range of 0.01  to 0.058
mg/1. For 1,577 samples of surface waters collected in 130
locations in  the United  States  the barium concentration in
1,568 samples ranged from  2  to 340 /ig/1 with a  mean of
43 Mg/1 (Kopp 1969).82
  Barium is recognized as a general muscle stimulant,
especially of the heart muscle (Sollmann 1957).86 The fatal
dose for  man  is considered to  be from 0.8 to 0.9 grams(g)
as the chloride (550 to 600 mg Ba). Most  fatalities have
occurred from mistaken use of barium salts incorporated in
rat poison.  Barium is capable  of  causing nerve block
(Lorente and  Feng 1946)84 and in small or moderate doses
produces transient increase  in  blood pressure by vaso-
constriction (Gotsev 1944).81
  There apparently has been no study made of the amounts
of barium that can be tolerated in drinking water, nor any
study of the effects of long-term feeding of barium salts
from  which  a  standard  might  be  derived.  The  present
barium standard has been developed from the barium-in-air
standard,  0.5 mg/cubic meter (m3)  (American Conference
of Governmental Industrial Hygienists  1958),80 based on
the retention of inhaled barium dusts, and an estimate of
the possible adsorption from  the intestines (Stokinger and
Woodward 1958).86 This value is 2 mg/1. The air standard
provides no indication of the inclusion of a factor of safety.
Therefore, it is reasonable  to provide a factor of safety of
2 for protection of heterogeneous population.

   Because of  the adverse physiological  effects  of
barium, and  because there are  no data on the
effectiveness of  the denned treatment process on
its removal, it  is recommended  that  a limit for
barium of 1 mg/1 not be exceeded in public water
supply sources.
   The previous Report of the Committee on Water Quality
 Criteria (FWPCA 1968)87 recommended a permissible limit
 of 1 mg/1 for boron. When a new Drinking Water Standards
 Technical  Review  Committee  was established in 1971,  it
 determined that the evidence available did  not indicate
 that  the suggested limit of 1  mg/1 was necessary. More
 information is required before deciding whether a specific
 limit is needed for physiological reasons.
   Whenever  public  water supplies  are  used to irrigate
 plants, boron concentrations may be of concern because
 of the element's effect on many plants.  For consideration
 of the possible effect of boron on certain irrigated plants,
 see Section V on Agricultural Uses of Water (p. 341).

  Cadmium is biologically a  nonessential, nonbeneficial
element. The possibility of seepage of cadmium into ground
water from electroplating plants was reported in 1954 when
concentrations ranging from 0.01 to 3.2 mg/1 were recorded
(Lieber and Welsch  1954).97 Another source of cadmium
contamination in water may  be zinc-galvanized  iron in
which cadmium is a contaminant. For 1,577 surface water
samples collected at 130 sampling points in the  United
States, 40 samples showed detectable concentrations  of 1
to 20 /tg/1 of cadmium with a  mean  level of 9.5 fig/I. Six
samples exceeded 10 ng/l (Kopp 1969).95
  Cadmium is an element of high toxic potential. Evidence
for the serious  toxic potential of cadmium is provided by:
poisoning  from cadmium-contaminated  food  (Frant  and
Kleeman  1941)92 and beverages (Cangelosi 1941);88  epi-
demiologic evidence that cadmium  may be associated  with
renal  arterial  hypertension   under  certain  conditions
(Schroeder 1965);102 epidemiologic association of cadmium
with Itai-itai disease in Japan (Murata et al. 1970);99 and
long-term  oral toxicity studies in animals (Fitzhugh  and
Meiller 1941,91 Ginn and Volker 1944,93 Wilson and DeEds
  Symptoms of violent nausea were reported for 29 school
children who had consumed fruit ice sticks containing 13-15
mg/1 cadmium (Frant and Kleeman 1941).92 This would be
equivalent to 1.3 to 3.0 mg of cadmium ingested.
  It has been  stated that the  concentration and  not the
absolute amount determines the acute toxicity of cadmium
(Potts  et al. 1950).101 Also, equivalent concentrations of
cadmium in water are considered more toxic than concen-
trations in food because of the effect of components in th
  The association of cardiovascular disease, particular!'
hypertension, with ingestion of cadmium remains unsettled
Although conflicting evidence has  been reported for ma]
(Schroeder 1965,102 Morgan 1969)98 and for animals (Kani
sawa  and Schroeder 1969,94 Lener and Bibr 197096), it  i
notable that hypertension  has not been associated  witl
Itai-itai disease (Nogawa and Kawano 1969).100
  In  view  of the cumulative retention  of  cadmium \y
hepatic (liver)  and  renal (kidney) tissue (Decker et al
1958,90 Cotzias et al.  1961,89 Schroeder and Balassa 1961103
and the  association  of  a severe endemic Itai-itai diseas<
syndrome with ingestion of as little as 600 jig/day (Yama
gata 1970),10S Drinking  Water Standards limit concentra
tions of cadmium to 10 ng/l so that the maximum dail;
intake of cadmium from waiter (assuming a 2 liter dairj
consumption) will not exceed 20 ng. This is  one-third th(
amount of cadmium derived  from food (Schroeder anc
Balassa 1961).103 A no-effect level for intake and accumula^
tion of cadmium in man has not been established.


  Because  of the adverse physiological effects ol
cadmium,  and because  there is inadequate infor-
mation on the effect of  the denned treatment
process on removal of cadmium, it is recommended
that  the cadmium concentration  in public water
supply sources not exceed 0.010 mg/1.

  Chloride ion in high concentrations, as part of the total
dissolved solids in water, can be detected by taste and can
lead to consumer rejection of the water supply. In undefined
high concentrations  it may enhance  corrosion of water
utility  facilities and  household appurtenances  (American
Water  Works Association 1971).106
  For the public water supplies of the 100 largest cities in
the United States, the median chloride concentration was
13 mg/1 with a range of 0 to 540 mg/1 (Durfor and Becker
  The  median chloride concentrations detected  by taste
by a panel of 10 to 20 persons were 182, 160, and 372 mg/1
from sodium, calcium, and magnesium salts respectively
(Whipple 1907).no The median concentration  identified
by a larger panel of 53 adults was 395 mg/1 chloride for
sodium chloride  (Richter  and MacLean  1939).109  When
compared with distilled water for a  difference  in  taste,
the median concentration was 61 mg/1. Coffee was affected
in taste when brewed with 210 and 222 mg/1 chloride from
sodium chloride  and calcium chloride respectively (Lock-
hart et al. 1955).108
  On the basis of taste and because of the wide range of
taste perception of humans, and the absence of information
on objectionable concentrations,  a limit for  public water
supplies of 250 mg/1 chloride appears to be reasonable where
sources of better quality water are or can be made available.
However, there may be a great  difference between a  de-
tectable concentration and an objectionable concentration,
and acclimatization  might be an  important factor.


  On the basis of taste preferences, not because of
toxic considerations, and because the denned treat-
ment process  does not  remove  chlorides,  it  is^
recommended  that chloride in public water supply
sources not exceed  250 mg/1  if sources  of  lower
levels are available.

  Chromium is  rarely found in natural  waters. It may
occur as a contaminant  from plating wastes,  blowdown
from cooling towers, or from circulating water in refriger-
ation equipment where it is used to control corrosion. It
has been found in some foods and in air. Chromium can
be detected in most biological systems. This does not prove
it essential, although there is reasonable evidence that it
does have a biological role (Mertz 1969).119
  For 1,577 surface water samples collected at 130 sampling
points in the United States, 386 samples  showed concen-
trations of 1  to  112 /ig/1 with a mean concentration of
9.7 Mg/1 for chromium (Kopp 1969).116
  The  hexavalent state of chromium is toxic to man, pro-
duces lung tumors when inhaled  (Machle and Gregorius
1948,117 U.S. Federal Security Agency, Public Health Serv-
ice  1953123), and readily induces skin sensitizations. Tri-
valent  chromium  salts show none of the  effects of the
hexavalent form  (Fairhall 1957).114 The trivalent form is
not likely to be present in waters of pH 5 or above because
of the very low solubility  of the hydrated oxide.
  At present, the levels of chromate ion that can be tolerated
by man for a lifetime without adverse effects on health are
undetermined. It is not known  whether cancer will result
from ingestion of chromium  in any of its valence  forms.
A  family of four  individuals is reported to have  drunk
water for a period of three years with as high as 0.45 mg/1
chromium in the hexavalent form without known effect
on their health, as determined by a single medical exami
nation (Davids and Lieber 1951).113
  Levels of 0.45 to 25 mg/1 of chromium administered t<
rats in chromate and chromic ion form in drinking wate
for one year produced no toxic responses (MacKenzie et al
1958).118 However, significant accumulation in the tissues oc
curred abruptly at concentrations above 5 mg/1. Naumov;
(1965)120 demonstrated that 0.033 mg of chromium froi)
potassium bichromate per  kilogram (kg) of body weigh
in dogs enhanced the  secretory and motor  activity of thi
intestines. Although there does not appear to  be a clearb
defined no-effect level, other studies (Conn et al. 1932,11
Brard  1935,111 Gross and Heller 1946,116 Schroeder et al
1963a,121 Schroeder et al. 1963b122) suggested that a concen
tration of 0.05 mg/1 with an average intake of 2 liters o
water per day would avoid  hazard to human health.

  Because of adverse physiological effects,  and be
cause there are insufficient data on the effect o
the  denned treatment process on the removal o:
chromium  in the  chromate  form,  it  is recom
mended that public water supply sources for drink'
ing  water contain  no more than 0.05 mg/1 tota

  Color in public water supplies is aesthetically undesirable
to the consumer and is economically undesirable to some
industries.  Colored substances can  chelate metal ions,
thereby interfering with coagulation  (Hall  and Packham
1965130),  and can  reduce the capacity of  ion exchange
resins (Frisch and Kunin I960).129 Another serious problem
is the ability of colored substances to complex or stabilize
iron and manganese and  render them more difficult  for
water treatment processes to remove (Robinson  1963,136
Shapiro 1964136).
  Although  the soluble colored substances in waters have
been studied for over 150 years, there is still  no general
agreement on their structure. A number of recent  studies
have indicated that colored substances are a complex mix-
ture of polymeric  hydroxy  carboxylic acids (Black  and
Christman 1963a,125 1963b,126 Lamar and Goerlitz 1963,133
Christman  and  Ghassemi  1966,128  Lamar   and Goerlitz
1966134) with the measurable color being a function of the
total organics concentration and the pH (Black and Christ-
man 1963a,126 Singley et al. 1966137).
  The removal of color can be accomplished by the defined
process when the dosage and the pH are adjusted as func-
tions of the raw water color (Black et al. 1963,127 American
Water Works Association Research  Committee  on Color
Problems  1967).124  These relationships may not apply to
colors resulting  from dyes and some other industrial  and
processing sources that cannot be measured by comparison
with the platinum-cobalt standards (Hazen  1892,131 1896,132
Standard  Methods  1971138).  Such colors  should  not be
present in concentrations that cannot be removed by the
defined process.


  Because  color  in  public water supply sources is
aesthetically undesirable and because of the limi-
tations of  the denned treatment  process,  a maxi-
mum of  75 platinum-cobalt color units is recom-

  Copper is frequently found in surface waters and in some
ground waters in low concentrations (less than 1 mg/1). It
is an essential and beneficial element in human metabolism,
and it is known that a deficiency in copper results in nu-
tritional anemia in infants (Sollmann 1957).Ml Because the
normal diet provides only little more than what is required,
an additional supplement  from water may ensure an ade-
quate intake. Small  amounts are generally regarded as
nontoxic; but large  doses may produce emesis, and pro-
longed oral administration may result in liver damage.
  For 1,577 surface water samples collected at 130 sampling
points in the United  States, 1,173 showed concentrations of
1 to 280 ^tg/1 with a mean concentration of 15 ^g/1 (Kopp
  Copper imparts some taste to  water,  but the detectable
range varies from  1  to  5 rng/1 (Cohen et  al. I960139)
depending upon the acuity of individual taste perceptions
Copper  in  public  water supplies enhances  corrosion  o
aluminum in particular and  of zinc  to a lesser degree. ^
limit of 0.1 mg/1 has been recommended to avoid corrosior
of aluminum (Uhlig 1963).142
  The limit of 1 mg/1 copper is based on considerations o
taste rather than hazards to health.

  To prevent taste problems and because there is
little information on the effect of the denned treat-
ment process on the removal of copper, it is recom-
mended that copper in public water supply sources
not exceed 1 mg/1.

  Standards for cyanide in water have been published by
the World Health Organization in "International Stand-
ards for  Drinking Water" (1963)148 and  the  "European
Standards for Drinking Water" (1970).149 These standards
appear to be based on the toxicity of cyanide  to fish, not
to man.  Cyanide in reasonable doses  (10  mg or  less)  is
readily converted to thiocyanate in the human body and in
this form is much less toxic to man. Usually,  lethal  toxic
effects occur only when the detoxifying mechanism is  over-
whelmed. The oral toxicity of cyanide for man  is shown in
the following table.
  Proper chlorination with a free  chlorine  residual under
neutral or alkaline conditions will reduce the cyanide level
to below the recommended limit.  The acute oral toxicity
of cyanogen chloride, the chlorination product of hydrogen
cyanide,  is approximately one-twentieth that of hydrogen
cyanide (Spector 1955).146
  On the  basis of the  toxic limit  calculated from the
threshold limit for air (Stokinger and Woodward 1958),147
      TABLE II-1—Oral Toxicity of Cyanide for Man
                                         Literature citations
2 9-4.7 mi/day. .
10 mj, single dose ..
19 mg/1 in water...

50-60 mg, single dose .
. Noninjiinous          Smith 194*«
 Nomnjunous          Bodansky and Levy 19231"
 Calculated from the safe thresh- StoKmger and Woodward 1958'"
  old limit for air
 Fatal              The Merck Index or Chemicals
                  and Drugs 1968"'
and assuming a 2-liter daily consumption of water contain-
ing 0.2 mg/1 cyanide as a maximum, an appreciable factor
of safety would be provided.


   Because of the toxicity of cyanide, it is recom-
mended  that a  limit of 0.2 mg/1 cyanide not  be
exceeded in public water supply sources.
                                          DISSOLVED OXYGEN
  Dissolved oxygen in raw water sources aids in the elimi-
nation of undesirable constituents, particularly  iron  and
manganese, by precipitation of the oxidized form. It  also
induces the biological oxidation  of ammonia to  nitrate,
and  prevents the anaerobic reduction of dissolved sulfate
to hydrogen sulfide. More importantly, dissolved  oxygen
in a raw surface water supply serves as an indicator  that
excessive quantities of oxygen-demanding wastes  are prob-
ably not present in the water, although there can be sig-
nificant exceptions to this. Therefore, it is desirable  that
oxygen in the water be at or near saturation. On the other
hand,  oxygen enhances  corrosion of treatment facilities,
distributing systems, and household appurtenances in many
  Oxygen depletion in unmixed bodies of water can result
from the presence of natural oxygen-demanding substances
as well as  from organic  pollution.  Lakes and  reservoirs
may contain little or no oxygen, yet may be essentially free
of oxygen-demanding wastes. This is because contact with
the air is limited to the upper surface, and because thermal
stratification  in  some  lakes and  reservoirs  prevents oxy-
genation of lower levels directly from the air. Similar con-
ditions also occur in ground waters.


   No recommendation is made, because the pres-
ence of dissolved oxygen in a  raw water supply has
both beneficial and detrimental aspects. However,
when the waters contain ammonia  or iron and
manganese in their reduced  form, the benefits of
the sustained  presence of oxygen at or near satu-
ration for a period of time can be greater than the

  The fluoride  ion  has potential beneficial effects,  but
excessive fluoride in  drinking water supplies produces ob-
jectionable dental fluorosis that  increases as a continuum
with increasing  fluoride concentration above  the  recom-
mended control limits. In the United States, this is the only
harmful  effect resulting from  fluoride found in drinking
water  (Dean 1936,150 Moulton  1942,188 Heyroth  1952,165
McClure  1953,167 Leone et al.  1954,156 Shaw 1954,159 U.S.
Department  of  Health,  Education, and Welfare,  Public
Health Service 1959160). The fluoride concentrations exces-
sive for a given  community depend on climatic conditions
because the amount of water (and consequently the amount
of fluoride) ingested  by  children  is  primarily influenced by
air temperature  (Galagan  1953,161 Galagan and Lamson
1953,152 Galagan and Vermillion  1957,153 Galagan et al.
  Rapid fluctuations in  raw water fluoride ion levels would
create  objectionable operating  problems  for  treatment
plants  serving communities that  supplement raw water
fluoride concentrations.  From the point of view of a water
pollution  control program any value less than that  recom-
mended would generally be acceptable at  a  point of do
mestic water withdrawal.

  Because of adverse physiological effects and  be-
cause  the defined treatment process does nothing
to reduce excessive fluoride concentrations, it i!
recommended that the maximum levels shown ir
Table II-2 not be exceeded in  public water supply
         TABLE 11-2—fluoride. Recommendation
 Annual averate of maximum daily air temperatures"
                                   Fluoride maximum mj/l
1 8
 • Bated on temperature data obtained lor a minimum ol live years.

                                           FOAMING  AGENTS
  Many chemical substances occurring either naturally or
as components of industrial or domestic waste will  cause
water to foam  when  agitated or when air is entrained.
The most common foaming agent in use today is the syn-
thetic anionic surfactant,  linear alkyl benzene sulfonate
(LAS). Branched alkyl benzene sulfonate (ABS) was used
prior to 1965 as a base for synthetic detergents. Because of
its persistent foaming properties, however, ABS was re-
placed by LAS.  The  most objectionable property of sur-
factants is  their  foaming capacity which  can  produce
unsightly masses of foam in a stream or at the home tap.
The surfactants also tend to disperse normally insoluble or
sorbed substances,  thus interfering with  their removal by
coagulation, sedimentation, and filtration.
  Although conversion to  the more readily biodegradable
linear alkyl sulfonates by  the detergent industry  has de-
creased  the persistence of sulfonates  in  aerobic  waters,
measurable concentrations of these substances still can be
found in both surface and ground waters.  Concentrations
of anionic surfactants in water can be determined by means
of their reaction with methylene blue dye (Standard Meth-
ods  1971).162 Concentrations of  less  than 0.5 mg/1, as
methylene blue active  substances (MBAS), do not cause
foaming or present serious interference in the defined treat-
ment process and  are well below the inferred limit (700
mg/1) of toxicity to humans based on tests on rats fed diets
of LAS (Buehler et al. 1971).161 It must be recognized that
this procedure does not determine the total concentration
of foaming agents, merely the concentration  of materials
that react with methylene blue, most of which are anionic
surfactants. Although cationic and nonionic synthetic sur-
factants do not respond, and not all substances  that respond
to the methylene blue process cause foaming, the methylene
blue test is the best available measure of foaming properties.


  To avoid undesirable aesthetic effects and be-
cause the denned treatment process does little or
nothing  to reduce the level of  foaming agents, it
is recommended that foaming  agents determined
as  methylene blue  active substances  not  exceed
0.5 mg/1 in public water supply sources.

  Hardness is defined as the sum of the polyvalent cations
expressed as the equivalent quantity of calcium carbonate
(CaCOs). The most common such cations are calcium and
magnesium.  In general, these  metal ions in public water
supply sources are not cause for concern to health, although
there are  some  indications  that they may influence  the
effect of other metal ions on some organisms (Jones 1938,168
Cairns, Jr. and  Scheier 1958,164 Mount 1966170). Possible
beneficial  and  detrimental  effects on  health  have been
postulated but not conclusively demonstrated (Muss 1962,171
Crawford  and Crawford  1967,166 Crawford et  al. 1968,165
Masironi  1969,169  Voors 1971172).  There  is considerable
variation in the range of hardness acceptable to a given
community.  Some consumers expect and demand supplies
with a total hardness of less than 50 mg/1, expressed as
equivalent CaCO3, while others  are  satisfied with total
hardness greater than 200  mg/1. Consumer sensitivity is
often related to  the hardness to which the public has be-
come accustomed, and acceptance may be  tempered by
economic considerations.
  The requirement for soap and other detergents is directl
related to the water hardness (DeBoer and Larson 1961).1'
Of particular importance is the tendency for developmer
of scale deposits when  the  water is heated. Variations i
water hardness may be more objectionable than any give
level. Waters with little or no hardness may  be corrosiv
to water utility facilities, depending upon pH, alkalinit;
and dissolved oxygen (American Water Works Associatio
1971).163 Industrial consumers of public supplies may b
particularly sensitive to variations  in hardness. A watt
hardness must relate to the level normal for the supply  an
exclude hardness additions resulting in significant variatior
or general increases.


  Acceptable levels for hardness are based on con
sumer  preference.  No  quantitative recommen
dation for hardness  in water can be specified.

  Iron (Fe) is objectionable in public water supplies because
of its effect on taste (Riddick et al. 1958,178 Cohen et  al.
I960176), staining of plumbing fixtures, spotting of laundered
clothes, and accumulation of deposits in distribution systems.
Iron  occurs  in  the  reduced  state (Fe++), frequently  in
ground waters and less frequently in surface waters, since
exposure to oxygen in surface waters results in oxidation,
forming hydrated  ferric  oxide which is much  less soluble
(American Water Works Association 1971).173
  Statistical  analysis of taste  threshold tests with iron  in
distilled water free of oxygen at  pH 5.0 showed that 5 per
cent of the observers were able to distinguish between 0.04
mg/1 ferrous iron  (added as ferrous sulfate) and  distilled
water containing no iron. At 0.3 mg/1, 20 per cent were
able to make the  distinction. When colloidal ferric oxide
was  added, 5 per  cent of the observers were able to dis-
tinguish between 0.7 mg/1 and distilled water. Thus the
form of iron  is important. The range of sensitivities of the
observers was surprising, in that 5 per cent were unable to
detect ferrous iron at a concentration of 256 mg/1 in distilled
water. The taste  of iron was variously described as bitter,
sweet, astringent,  and "iron tasting." (Cohen et al. I960).176
  Concentrations of iron less than  0.3 mg/1 are generally
acceptable in public water supplies as the characteristic
red stains and deposits of  hydrated  ferric oxide do  not
manifest themselves (Hazen 1895,m Mason 1910,177 Buswell
1928174). This is the principal reason for limiting the con-
centration of soluble iron.


  On the basis  of user preference and because the
defined treatment process can remove oxidized iron
but may not remove soluble iron (Fe++), it is recom-
mended that 0.3 mg/1 soluble iron not be exceeded
in public water supply sources.

  Lead is well known for  its  toxicity in both acute and
chronic exposures (National Academy of Sciences  1972).190
In technologically developed countries the widespread use
of lead multiplies the risk of exposure of the population to
excessive lead levels (Kehoe  1960a).184 For  this reason,
constant surveillance of the lead  exposure  of the general
population via food, air, and water is necessary.
  Acute lead toxicity is characterized by burning in the
mouth,  severe thirst, inflammation  of the gastrointestinal
tract with vomiting and diarrhea. Chronic toxicity produces
anorexia, nausea, vomiting, severe abdominal pain, paraly-
sis, mental confusion, visual disturbances, anemia, and con-
vulsions (The Merck Index of Chemicals and Drugs  I960).189
  For 1,577 surface water samples collected from 130 sam-
pling points in the United States,  11.3 per cent showed
detectable concentrations of 0.002  to 0.140 mg/1 with a
mean of 0.023 mg/1 (Kopp 1969).187 For the  100 largest
cities in the  United States,  the finished waters were  found
to have  a  median  concentration of 0.0037 mg/1 and a
maximum of 0.062 mg/1 (Durfor  and Becker 1964).182  Of
the 969 water supplies in a  community water supply study
conducted in 1969 (McCabe et al. 1970),188 the lead concen-
trations in finished water ready for distribution ranged from
0 to  0.64 mg/1. Fourteen of these supplies on the  average
exceeded the 0.05 mg/1 limit  for lead in drinking  water
(PHS 1962).191 Of 2,595 samples from distribution  systems,
37 exceeded the limit set by the Drinking Water Standards
(PHS 1962).191 When standing in lead pipe overnight,  acidic
soft water in particular can dissolve appreciable  concen-
trations of lead (Crawford and Morris 1967).181
  The average daily intake of lead via the diet was 0.3 mg
in 1940 and rarely exceeded 0.6 mg (Kehoe et al. 1940a).186
Data obtained subsequent to 1940  indicated that the intake
of lead appeared to have decreased slightly  since that time
(Kehoe 1960b,185 Schroeder and Balassa  1961).192 Whe
under  experimental  conditions,  the daily  intake of lez
from all sources amounted  to 0.5 to 0.6 mg over one ye;
or more, a small amount was retained in normal healtl
adults  but produced no detectable deviation from norm
health. Indirect evidence from industrial workers expost
to known amounts of lead  for long periods was consistei
with these findings (Kehoe  1947).183
  Young children present a special case in lead intoxicatio
both in terms of the tolerated intake and the severity of tl
symptoms (Chisholm 1964).180 The most prevalent soun
of lead poisoning of children up to three years of age h,
been lead-containing paint still found in some older horn
(Byers 1959,179 Kehoe 1960a184).
  Because of the narrow gap between the quantities of lea
to which the general population is exposed through foe
and air in the course of every day life, and the quantities th;
are potentially  hazardous over  long periods of time, lea
in water for human consumption must be limited to lo
  A long-time intake of 0.6 mg  lead per day is a level ;
which  development of lead  intoxication is unlikely and ti
normal intake  of lead from  food is  approximately 0
mg/day. Assuming a 2 liter daily  consumption of wati
with 0.05 mg/1 lead, the additional daily intake would t
0.1 mg/day or 25 per cent of the total intake.

  Because of  the  toxicity of lead to humans an
because there is little information on the effective
ness of the defined treatment process in decreasin
lead concentrations, it  is recommended that 0.0
mg/1  lead not be  exceeded in public water suppl

  Manganese (Mn) is objectionable in public water supplies
because of its effect on taste (Riddick et al. 1958,196 Cohen
et al. I960194), staining  of plumbing fixtures, spotting of
laundered clothes, and accumulation of deposits in  distri-
bution systems. Manganese  occurs  in  the  reduced state
(Mn++), frequently  in ground waters and less frequently
in surface  waters, since exposure to  oxygen  in  surface
waters results in oxidation to much less soluble hydrated
manganese oxides (American Water  Works Association
  Concentrations  of manganese less than 0.05  mg/1 are
generally acceptable in public water supplies, because the
characteristic black stains and deposits  of hydrated man-
ganese oxides do not manifest  themselves.  This is the
principal reason for limiting the concentration of soluble
manganese (Griffin I960).196

  On the basis of user preference and because the
defined  treatment  process can remove oxidized
manganese but does little to remove soluble man-
ganese (Mn++), it is recommended that 0.05 mg/1
soluble manganese  not be exceeded in public water

  Mercury (Hg) is distributed throughout the environment.
As a result of industrial use and agricultural  applications,
significant local increases in concentrations above natural
levels in water, soils, and air have been recorded (Wallace
et al. 1971).209  In addition to the more  commonly known
sources of  man's mercury contributions,  the burning  of
fossil fuels has been reported as a source of mercury pollution
(Bertine and Goldberg 1971,199 Joensuu 1971202).
  The presence of mercury in fresh and sea water was
reported many years ago (Proust 1799,204 Garrigou 1877,201
Willm 1879,210 Bardet 1913197).  In  Germany,  early studies
(Stock and Cucuel 1934,206 Stock  1938206) found  mercury
in tap water,  springs, rain water,  and beer.  In  all water
the concentration  of mercury  was consistently  less than
one Mg/1, but the beer occasionally contained up to 15 ng/'l.
A recent survey (U.S. Department of Interior, Geological
Survey  1970)2U demonstrated  that 93  per  cent of U.S.
streams and rivers sampled contained less than 0.5 Mg/1 of
dissolved mercury.
  Aside from  the  exposure experienced in certain  occu-
pations, food,  particularly fish,  is the greatest contributor
to the human body  burden of  mercury (Study Group on
Mercury Hazards  1971).208 The Food and Drug Adminis-
tration (FDA)  has established  a guideline of 0.5 mg/kg
for  the maximum  allowable concentration of mercury  in
fish consumed  by  humans, but it  has not been  necessary
for the FDA to establish guidelines for other foodstuffs.
  Mercury poisoning may be acute or chronic. Generally,
mercurous salts are less soluble  in  the digestive tract than
mercuric salts and are consequently less acutely toxic. For
man the fatal oral dose of mercuric salts ranges from 20 mg
to 30 mg (Stokinger 1963).207 Chronic poisoning  from in-
organic mercurials has  been most often  associated with
industrial exposure, whereas that from the organic deriva-
tives  has been the  result of accidents  or environmental
  On the basis of their effects on man, several of the mercury
compounds  used  in agriculture and  industry  (such  as
alkoxyalkyls and aryls)  can be grouped with  inorganic
mercury  to which the former compounds are usually me-
tabolized. Alkyl compounds are the derivatives of mercury
most  toxic  to man, producing illness from the ingestion of
only a few milligrams. Chronic alkyl mercury poisoning is
insidious in that it may be  manifest after a few weeks  or
not until after a few years.
  It has been estimated (Bergrund and Berlin 1969)198 tha
of the total mercury ingested, more than 90 per cent  i
absorbed via the gastrointestinal tract when taken in th
form of methyl mercury; bu t only 2 per cent is absorbed .
it is in the form of mercuric ion (Clarkson  1971),20° Huma
excreta reveal a biological half-life of methyl mercury i
man of approximately 70 dziys (Study Group on Mercur
Hazards 1971).208
  Acute mercury toxicity is c haracterized by severe nausea
vomiting, abdominal pain, bloody diarrhea, kidney damage
and  death usually  within ten  days.  Chronic exposure  i
characterized by inflammation of mouth and gums, swelling
of salivary glands, excessive salivation, loosening of teeth
kidney  damage,  muscle  tremors, spasms of extremities
personality changes, depression,  irritability, and nervous
ness  (The Merck Index of Chemicals and  Drugs  I960).203
  Safe levels of ingested  mercury can be estimated fron
data presented in "Hazards of Mercury" (Study  Group 01
Mercury Hazards 1971 ).208 From epidemiological evidence
the  lowest  whole blood concentration of  methyl mercun
associated with toxic symptoms is 0.2 Mg/g, which, in turn
corresponds to prolonged, continuous intake by  man o
approximately 0.3 mg Hg/70 kg/day. When a safety facto
of 10 is used, the maximum dietary  intake should be O.CK
mg  Hg/person/day  (30 /ig/70 kg/day).  It is recognizec
that  this provides  a smaller  factor of safety for children
If exposure to mercury were  from fish alone, the 0.03 mi
limit  would allow for a maximum  daily consumption o
60 grams  (420  g/week) of fish containing 0.5 mg Hg/kg
Assuming a daily consumption of 2 liters of water containing
0.002 mg/1  (2  Mg/1) mercury,  the daily intake  would b<
4 Mg- If 420 g of fish per week containing 0.5 mg Hg/k£
plus  2 liters of water daily containing 0.002 mg/1 mercur;
were ingested, the factor of safety for a 70 kg man wouk
be 9. If all  of the mercury is not in the  alkyl form,  or  i
fish consumption is limited, a greater  factor of  safety  wil


  On the basis of adverse physiological effects  and
because  the defined water treatment process  has
little or no effect on removing mercury at low levels,
it is recommended that  total mercury in  public
water supply sources not  exceed 0.002 mg/1.

  Serious and occasionally fatal poisonings in infants have
occurred following ingestion of well waters shown to contain
nitrate  (NOs_)  at  concentrations greater than  10  mg/1
nitrate-nitrogen (N). This was first associated with  a tempo-
rary blood disorder in infants  called methemoglobinemia
in 1945 (Comly 1945).212 Since then, approximately  2,000
cases of this disease have been reported from private water
supplies in North America and  Europe,  and about  7  to
8 per cent of the infants  affected died  (Walton 1951,223
Sattelmacher 1962,218 Simon et  al. 1964219).
  High nitrate  concentrations are  frequently found  in
shallow wells on farms and in rural communities. These
are often  the  result of inadequate protection  from barn
yard drainage and from septic  tanks (U.S. Department of
Health, Education, and  Welfare, Public Health Service
1961,221 Stewart et  al.  1967220). Increasing concentrations
of nitrate in streams from farm  tile drainage  have been
shown in regions of intense fertilization and  farm crop
production (Harmeson et al. 1971).214
  Many infants have  drunk water  with nitrate-nitrogen
concentrations greater  than 10 mg/1 without  developing
the disease. Many public water  supplies in  the United
States  have levels  of  nitrate  that  routinely  exceed  the
standard,  but only one case of methemoglobinemia (Vigil
et al. 1965)222 associated with  a  public water  supply  has
thus far been reported. Rationale for degrees of  suscepti-
bility to methemoglobinemia have yet to  be  developed.
  The development of methemoglobinemia, largely  con-
fined  to infants  less than  three months old, is dependent
upon  the  bacterial  conversion  of the relatively innocuous
nitrate ion  to nitrite  (NO2~).  Nitrite absorbed  into  the
blood stream converts hemoglobin to methemoglobin. The
altered pigment can then  no longer transport oxygen, and
the clinical effect of methemoglobinemia is that of oxygen
deprivation or  suffocation. Older children and adults do
not seem to be  affected,  but  Russian research  reported
methemoglobin  in  five- to eight-year-old school  children
where the water nitrate concentrations were  182 mg/1 as N
(Diskalenko 1968).213
  Nitrite  toxicity is well known,  but a no-effect  level  has
not been established.  When  present in drinking  water
nitrite would  have a  more rapid and pronounced  effect
than  nitrate.  Concentrations  in  raw water  sources  are
usually less than 1  mg/1 as N, and  chlorination  to a free
chlorine residual converts  nitrite to nitrate.
  Several  reviews  and reports  (Walton  1951,223  Sattel-
macher  1962,218 Simon  et al.  1964,219  Winton 1970,224
Winton et al. 1971225) generally pointed to 10 mg/1 nitrate-
nitrogen in drinking water as the maximum tolerance levels
for  infants.  Sattelmacher  (1962)218  showed  3  per cent  of
473 cases of infantile methemoglobinemia to be associated
with levels of less than 9 mg/1 as N. Simon and his associates
(1964)219 found 4.4 per  cent of 249 cases  to be associated
with levels less than 11 mg/1  as N. Analyses  of available
data are hampered  by the fact that samples for water
analysis are sometimes collected weeks or months after the
disease  occurs, during  which  time the  concentration  of
nitrate may change  considerably. Hereditary defects, the
feeding  of  nitrate-rich vegetables, or the use  of common
medicines  may  increase susceptibility to  methemoglobi-
nemia. Winton and his  associates (1971)228 concluded that
"there is insufficient  evidence to permit raising the recom-
mended limit."
  Extensive reviews on methemoglobinemia associated with
nitrate and nitrite have been provided by Walton (1951),223
Miale  (1967),216 and Lee  (1970).216  They described the
circumstances  that contributed to the susceptibility of in-
fants under three  months  of  age to methemoglobinemia
from nitrate. These included (a) the  stomach pH in infants,
which is higher than that of adults and can permit growth
of bacteria that can reduce nitrate to nitrite, and (b) infant
gastrointestinal illness that may permit reduction of nitrate
to nitrite to occur higher in the intestinal tract.
  Methemoglobin is normally present at levels of 1 per cent
to 2 per cent of the total hemoglobin in the blood. Clinical
symptoms are normally detectable  only at levels of about
10  per cent. Methemoglobin in the subclinical range has
been  generally  regarded  as  unimportant. However,  10
children (ages 12 to 14) were observed to have shown con-
ditioned reflexes to both auditory and visual stimuli, as the
result of a drinking  water source with 20.4 mg/1 nitrate-
nitrogen. The average  methemoglobin  in the blood was
5.3 per cent (Petukhov  and Ivanov 1970).217

  On  the basis of  adverse  physiological effects on
infants and  because  the denned treatment process
has no effect on  the removal of  nitrate, it is recom-
mended that the  nitrate-nitrogen  concentration
in  public water supply sources  not exceed  10 mg/1.
  On  the basis of its high toxicity  and  more pro-
nounced  effect  than nitrate,  it is recommended
that the  nitrite-nitrogen  concentration in public
water supply sources not exceed  1 mg/1.

                                     NITRILOTRIACETATE  (NTA)
  Because of its possible large-scale use, nitrilotriacetate
(NTA) should be evaluated in light of chronic low-level
exposure via drinking water and its potential for adversely
affecting the health of the general  population. Although
nitrilotriacetic acid, a white crystalline powder, is insoluble
in water, the tribasic salt is quite soluble.
  NTA has strong affinity for iron, calcium, magnesium,
and  zinc  (Bailar  1956).226 Its relative  affinity for toxic
metals such as cadmium and mercury is not presently
known, nor have its chelating properties in complex ionic
solutions  been characterized.  Copper  and  lead concen-
trations in biologically treated waste water after flocculation
with aluminum sulfate (125 mg/1)  are  a function  of the
NTA present (Nilsson 1971).227 No information is available
on the toxicity of such chelates.  No cases of acute human
poisoning by NTA have been reported.
  In the natural environment, NTA is biodegraded to CO2,
   s, and H2O, with glycine and ammonia as intermediate
(Thompson and Duthie 1968).228 This appears to occu
within  four to  five days.  Degradation is accelerated  b
biological waste treatment.  Conversion of NTA to nitrat
is on a 1 to 1  molar basis.


  No recommendation concerning NTA is made a
this time because of the absence of data on affinit
for toxic metals, the  absence of adequate toxicit
data, and the absence  of demonstrable effects 01
man, and because there is doubt about its potentia
use as a substitute for  phosphates in detergents
Toxicity  information should  be  developed  ant
evaluated to  establish  a reasonable  recommen
dation prior to its use as a substitute.
  Odor and  taste, which are rarely separable, are  the
primary means by which the user determines the accepta-
bility of water. The absence of odor is an indirect indication
that contaminants such as phenolic compounds are also
absent, or nearly so.  (See Phenolic Compounds, in this sec-
tion, p. 80) Although odor cannot  be directly correlated
with the safety of the water supply,  its presence can cause
consumers to seek other supplies that may in fact  be  less
  Many odor-producing substances  in raw water supplies
are organic compounds produced by microorganisms and
by  human and  industrial wastes  (Silvey  1953,232  Rosen
1966,231 American  Water Works Association, Committe
on  Tastes  and Odors,  1970230). The denned treatmer
process can aid  in the  removal of certain odorous sul:
stances (American  Water Works Association 1971),229 bu
it may in other cases increase the odor (Silvey et al. 1950)2:
as by  the chlorination of phenolic compounds explaine
on p. 80.

  For  aesthetic  reasons,   public  water  suppl
sources should be essentially free from objection
able odor.
                                          OIL  AND  GREASE
  Oil and grease, as defined by Standard Methods (1971),241
occurring in public  water supplies in any quantity cause
taste, odor, and appearance problems (Braus et al. 1951,235
Middleton  and Lichtenberg  I960,240 Middleton 196la,239
American Water Works Association 1966234),  can be haz-
ardous to human health (The Johns Hopkins University,
Department of Sanitary Engineering and Water Resources
1956,237 McKee  and Wolf 1963238), and are  detrimental
to the defined treatment process (Middleton and Lichten-
berg I960).240 Even  small quantities of oil and grease can
produce objectionable odors and appearance, causing re
jection of the water  supply  before health or treatmer.
problems exist (Holluta 1961,2:t6 McKee and Wolf  1963).2;
   On  the basis of  odor and other aesthetic con
siderations affecting user preference and becaus
oil and grease are unnatural ingredients in watei
it is recommended that public water supply source
be essentially free from oil and grease.

                                 ORGANICS-CARBON  ADSORBABLE
  Organics-carbon adsorbable are composed  of carbon-
chloroform extract (CCE) (Middleton 1961 b)246 and carbon-
alcohol  extract (CAE)  (Booth et al.  1965,243 Standard
Methods 1971248). CCE is a mixture of organic compounds
that can be adsorbed on activated carbon and then desorbed
with chloroform (Booth et  al. 1965).243 Middleton  and
Rosen (1956)246 showed the presence of substituted benzene
compounds,  kerosene,  polycyclic  hydrocarbons, phenyl-
ether, acrylonitrile, and insecticides in CCE  materials.
CAE is  a mixture  of organic compounds that can be ad-
sorbed on activated carbon, then desorbed with ethyl alcohol
after the chloroform soluble organics have been desorbed
(Booth et al. 1965).243
  Hueper and Payne (1963)244 showed that CCE materials
had carcinogenic  properties when ingested by  rats. This
study also suggested a life-shortening effect in rats fed CAE
materials (Federal Water Pollution Control Administration
office memorandum 1963).249 The CAE material also contained
at least  one  synthetic organic,  alkyl  benzene sulfonate
(Rosen et al. 1956).247
  It is important to recognize that the carbon usually does
not adsorb all organic material  present,  nor  is  all the
adsorbed material desorbed.
  Organics-carbon adsorbable recommendations represent
a practical measure of water quality and act as a safeguard
against  the intrusion of excessive amounts of  ill-defined
potentially toxic organic material into water. They have
served in the past  as a measure of protection against the
presence of otherwise undetected toxic organic materials in
drinking water. However, they provide a rather incomplete
index of the health significance of such materials in potable
  In 1965 Booth and his associates (1965)243 developed a
Carbon  Adsorption Method (CAM)  similar to  the High-
Flow  CAM Sampler but with a longer contact time be-
tween the sample and the activated carbon. This sampler,
called  the  Low-Flow CAM Sampler,  increased organic
adsorption and therefore overall yield of the determination.
  Since that time a more  reliable  collection apparatus,
called the Mini-Sampler, has been developed (Beulow and
Carswell 1972).242 In addition, the Mini-Sampler also used
a type of coal-based activated carbon that enhanced organic
collection.  Further, the extraction  apparatus has  been
miniaturized  to  be less  expensive and more  convenient,
and the procedure modified to be more vigorous, thereby
increasing desorption and organic recovery (Beulow and
Carswell 1972).242 However,  the Mini-Sampler has not
been evaluated using raw waters at this time. Therefore,
the Low-Flow Sampler (Booth et al. 1965)243 was used for
establishing the recommendation.
  Adjustment of the High-Flow Sampler data (1961  Inter-
state Carrier Surveillance Program) to make them  com-
parable to  the recent results from the  Low-Flow Sampler
show that waters with concentrations exceeding either 0.3
mg CCE/1  or  1.5 mg  CAE/1  may contain  undesirable
and unwarranted components  and represent  a  generally
unacceptable level for unidentified organic substances.


  Because large values of CCE and  CAE are aes-
thetically undesirable and represent unacceptable
levels of unidentified  organic compounds that may
have adverse physiological effects, and because the
defined treatment process has little or no effect on
the removal of these organics, it  is recommended
that  organics-carbon adsorbable  as measured by
the Low-Flow Sampler (Standard Methods 1971248)
not exceed 0.3 mg/1 CCE and 1.5 mg/1  CAE  in
public water supply sources.

  Pesticides include a great many organic compounds that
are used for specific or general purposes. Among them are
chlorinated  hydrocarbons, organophosphorus and carba-
mate compounds, as well as the chlorophenoxy, and other
herbicides. Although these compounds have been useful in
improving agricultural  yields,  controlling  disease vectors,
and reducing the mass growth of aquatic plants in streams
and reservoirs, they also create  both real  and presumed
hazards in the environment.
  Pesticides differ widely in chemical and toxicological
characteristics.  Some are accumulated in the fatty tissues
of the body while others are metabolized. The biochemistry
of the pesticides has not yet  been completely investigated.
Because of the variability in their toxicity to man and their
wide  range of biodegradability, the different  groups of
pesticides are considered separately below.
  Determining the presence of pesticides in water requires
expensive specialized equipment as well as specially trained
personnel. In smaller communities, it is not routine to make
actual  quantitative   determinations  and  identifications.
These are relegated  to  the larger cities, federal and state
agencies,  and private laboratories that monitor raw waters
at selected locations.

  The chlorinated hydrocarbons are one of the most im-
portant groups of synthetic organic insecticides  because of
their number, wide use,  great stability in the environment,
and toxicity to certain forms of wildlife and other nontarget
organisms. If absorbed  into the human body, some of the
chlorinated  hydrocarbons are not metabolized rapidly but
are stored in fatty tissues. The consequences of such storage
are presently  under  investigation  (Report of  the Secre-
tary's Commission on Pesticides and Their Relationship to
Environmental Health. U.S. Department of Health,  Edu-
cation, and Welfare 1969).284 The major chlorinated hydro-
carbons have been in use for  at least three decades, and yet
no  definite  conclusions  have been reached  regarding the
effect of these pesticides  on man (HEW 1969).284
  Regardless  of  how they  enter  organisms,  chlorinated
hydrocarbons cause symptoms of poisoning that are similar
but differ in severity. The severity is related to concentratioi
of the chlorinated  hydrocarbon  in  the nervous  system
primarily the brain (Dale et al.  1963).266 Mild intoxicatioi
causes headaches, dizziness, gastrointestinal  disturbances
numbness and  weakness of the  extremities,  apprehension
and hyperirritability. In severe cases, there are muscula
fasciculations spreading from the head to the extremities
followed eventually  by spasms involving  entire muscli
groups, leading in some cases to convulsions and death.
  Very few long term  studies have been conducted  witl
human volunteers. The highest level tested for dieldrin wa
0.211  mg/man/day for 2  years with no observed illnes
(Hunter and Robinson 1967,:!68 Hunter et al.  1969).269 Sino
aldrin is metabolized to  dieldrin and has essentially thi
same toxicity as dieldrin,  these  data  can also be applie(
to aldrin.
  Methoxychlor  levels  of  140 mg/man/day produced  n<
illness in subjects over a  period of 8 weeks (Stein  et  al
1965).280 The  maximum  level  of DDT  seen to have  n<
apparent ill effect was 35 mg/man/day for 2 years (Haye
et al. 1971).265
  The dosage  is one of the most important factors in ex
trapolating to  safe human exposure levels.  Using tumor
susceptible hybrid  strains  of mice,  significantly increaset
incidences of tumors were produced with the administratioi
of large doses of DDT (46.4  mg/kg/day)  (Innes  et  al
1969).270 In a  separate study in mice extending over fivi
generations, a  dietary level of 3 ppm of  DDT produced <
greater incidence of malignancies and leukemia beginning
in the second filial and third filial generations, respectively
and continuing in the later generations (Tarjan and Kemen)
1969).281 These results are preliminary in nature and requin
confirmation. The findings of both of these studies conflic
with earlier studies of the carcinogenic effect  of DDT whicl
yielded generally negative results.
  A summary of the levels of  several chlorinated hydra
carbons  that produced minimal toxicity or no effects wher
fed chronically to dogs and rats is shown in Table 11-^
(Lehman 1965,272 Treon  and Cleveland 1955,282 Cole un-
published data 1966286). Limits for chlorinated hydrocarbon;
in drinking water have been calculated primarily on the

                       TABLE II-3—Recommended Limits for Chlorinated Hydrocarbon Insecticides

Chlordane ...





Htpbchlor Epoiide .

Lindane .



Long-term levels with minimal or no effects
ppm in diet














mg/kf body Reference
0.083 .
0.003 (2), (3)
0.42 . ..
0.5 (4)
0.003 (2), (3)
0 83
2.0 (7)
1 7
Calculated maximum sale levels
from all sources of exposure
Safety Factor














0.01 12*



11. ¥
78/Section II—Public Water Supplies
consider the exposure from other media. In the case of the
chlorinated  hydrocarbons, exposure  is expected to occur
mostly through  the  diet, although aerial  spray  of these
agents can occasionally result in an inhalation exposure.
Dietary intake of pesticide chemicals from  1964  to 1970
have  been determined by investigators of the  Food and
Drug Administration from  "market  basket"  samples of
food and  water  (Duggan and Corneliussen 1972).268 The
average intakes (mg/man/day) are listed in Table II-3.
  If the intake from the diet  is  compared with what are
considered acceptable safe levels for these pesticides, it is
apparent that only traces of chlordane, methoxychlor, and
toxaphene are present in  the diet. Less than  10 per cent of
the maximum safe level of aldrin, DDT, endrin, heptachlor,
or lindane are ingested with the diet. For dieldrin, approxi-
mately 35 per cent of the safe level  comes from the diet.
By  contrast,  exposure to heptachlor epoxide via  the diet
accounts for more than the defined safe level. In general, an
apportionment to water of 20 per cent of the total acceptable
intake is reasonable. However, the limits for chlordane and
toxaphene were lowered  because of organoleptic effects at
concentrations above 0.003  and 0.005 mg/I, respectively
(Cohen et al. 1961,253 Sigworth 1965278). The limit  for
heptachlor epoxide was lowered to five per cent of the safe
level because of the  relatively high concentrations  in the
diet; and,  accordingly, the limit for heptachlor was lowered
because it is metabolized  to heptachlor epoxide.
  These limits reflect the amounts that can be  ingested
without harm to the health  of the consumer and without
adversely affecting the quality of the drinking water. They
are meant to serve only in the event that these chemicals
are inadvertently present in the water and do not imply
that their  deliberate addition is acceptable.
  Because of adverse  physiological effects on hu-
mans or on the quality  of the water and because
there is  inadequate information on the effect  of
the denned treatment on removal of chlorinated
hydrocarbons, it is  recommended that the limits
for water shown in Table II-3 not be exceeded.

  The number of organophosphorus and carbamate  in-
secticides  has steadily increased through special  uses in
agricultural  production and  the  control of destructive  in-
sects. At present,  there  are  perhaps 30  commonly used
organophosphates with parathion among those potentially
most  dangerous  to human  health.  No evidence  has de-
veloped of any significant contamination of water supplies
even in the  geographical areas where the use of pesticides
in this class has been extensive. However, because of their
high mammalian toxicity, it is  advisable to establish  an
upper limit for these pesticides in treated water supplies.
  The majority of organophosphorus insecticides in use at
present are somewhat similar in chemical structure and
physical and biological properties. Although their speci
chemical compositions differ from one another  and frc
carbamates, they all act by the same physiological meet
nism. Their presence in public water supplies  as contan
nants would result in some deleterious biological efft
over a period of time.
  Ingestion of small quantities of either of these pesticic
over a prolonged  period  results  in a  dysfunction  of  t
cholinesterase of the nervous system (Durham and Ha}
1962).259 This appears to  be the  only important manifi
tation of acute or chronic toxicity caused  by these coi
pounds (HEW  1969).M4
  Although safe levels of these; agents have been determin
for experimental animals on the basis of biochemical in<
cators of injury, more knowledge is needed to make speci
recommendations for water quality (HEW 1969).284
  Indications  of the  levels that  would be harmful  a
available for some organophosphorus compounds as a resi
of studies conducted with human volunteers. Grob (1950)
estimated  that  100 mg of parathion would  be lethal ai
that 25 mg would be moderately toxic. On the other han
Bidstrup (1950)261 estimated that a dose of 10  to 20 mg
parathion   might be  lethal.  Edson  (1957)260  found th
parathion  ingested by man at a rate of 3 mg/day had ]
effect on cholinesterase. Similar values were determined 1
Williams and  his associates  (1958).28B Moeller  and Rid
(1962)273 suggested that the detectable toxicity threshol
as measured by cholinesterase depression, was 9 mg/d;
for  parathion equivalency and 24 mg/day  for malathio
These investigators also reported that a daily dose of 7  n
of methyl parathion was near the detectable toxicity thres
old for this compound; but  it was later found (Rider ar
Moeller 1964)276 that  10 mg/'day  of methyl  parathion cl
not  produce any  significant inhibition of  blood choli
esterase. Therefore, 5 mg/day (0.07 mg/kg/day) of p>
rathion equivalency should be a safe intake acceptable
the body.
  Frawley and  his associates (1963)262 found  that a depre
sion of plasma  cholinesterase occurred in human subjec
at a dosage of 0.15 mg/kg/day of Delnav,  which wou
amount to a total dose of about 7 to 10 mg/day of parathk
depending on the body weight of  the subjects.
  On the  basis that carbamate and organophosphorus i
secticides  have  similar toxic effects and that parathion
one of the most toxic of these classes, the data appeared
show that  0.07 mg/kg/day  should be a safe level for tl
human body. Assuming a daily consumption of 2 liters
water containing cholinerglc organophosphates  or carb
mates in concentrations of 0.1  mg/1, 0.2 mg/day would I
ingested. This would  provide  a factor  of safety of 25  f<
parathion  for a man weighing 70 kg.

Recom mendat ion
  It  is  recommended  that  the  carbamate  an
organophosphorus  pesticides in public water suf

                      TABLE II-4—Recommended Allowable Levels for Chlorophenoxy Herbicides
                        Lowest long-term levels with minimal or no effects
Calculated maximum safe levels from all sources of exposure
                             Dose mg/kg/dar
                                                         Safety factor (X)
                                                                                            ~% of Safe Level   Rec. limit (mg/l)°
2,4-D.. ..


2,4,5-T .



Lehman (1965)"=
Lehman (1965)™
Mullison (1966)"<
Mullison (1966)"'
Courtney etal. (1970)2=i
Courtney & Moore (1971)"'
Drill & HiraMa (1953)2"


1 12







 - Assume weight of rat=0.3 kg and of dog=10 kg; assume average daily food consumption of rat=0.05 kg and of dot=0.2 kg.
 *> Assume average weight of human adult=70 kg.
 « Assume average daily intake of water for man=2 liters.
 <* Chosen as basis on which to derive recommended level.
ply sources not exceed 0.1 mg/1, total, because there
is inadequate information on  the effect of the de-
fined treatment process on their removal.

  During the past 20 years, numerous reservoirs have been
constructed as  public water supplies for  cities and com-
munities in the United States. In certain areas as much as
five per cent per year of the total volume of a reservoir may
be lost because of the marginal growth  of weeds and trees.
This is  especially common in the  Southwest where water
levels fluctuate (Silvey 1968).279
  In recent years the control of aquatic vegetation has been
widely practiced for water supply sources in many com-
munities in the U.S. Since herbicides may be used for this
purpose, it is possible that some may find their way into
finished water.
  Two of the most widely  used herbicides  are 2,4-D (2,4-
dichlorophenoxyacetic  acid), and  2,4,5-TP  (2,4,5-tri-
chlorophenoxy-propionic acid)  (see Table  11-4). Each of
these compounds is available in  a variety of salts and esters
that may have marked differences  in herbicidal properties
but are  rapidly  hydrolyzed to  the corresponding acid in
the body. There  are additional compounds that have been
employed from time to time, such as diquat (1,1 '-ethylene-2,
2'-dipyridylium dibromide)  and endothal (disodium 3,6-
  Studies  of the acute oral toxicity of the chlorophenoxy
herbicides indicated that there was approximately a three-
fold  variation  between the species studied and  that  the
acute toxicity  was  moderate (Hill  and Carlisle  1947,267
Lehman  1951,271 Drill and Hiratzka 1953,2"  Rowe and
Hymas  1954).277 It appears that acute  oral toxicity of the
three  compounds is of about the same magnitude within
each species. In the  rat, the oral LD50 for each agent was
about 500 mg/kg.
  There are some data available on the toxicity  of 2,4-D
to man  indicating that a  daily dosage  of 500 mg  (about
7 mg/kg)  produced no apparent  ill  effects in a volunteer
over a 21-day period (Kraus unpublished 1946).288
  Sixty-three million pounds of 2,4-D were  produced in
1965. There were  no confirmed cases of  occupational
poisoning and few instances of any illness due to ingestion
(Hayes  1963,264 Nielson et al. 1965275). One case of 2,4-D
poisoning in man has been reported recently (Berwick
  Lehman (1965)272 reported  that  the no-effect level ot
2,4-D is 0.5 mg/kg/day in the rat and 8.0 mg/kg/day in
the dog. In 2-year  feeding  studies  with the sodium and
potassium  salts  of silvex,  the  no-effect levels  were  2.6
mg/kg/day in  rats  and 0.9 mg/kg/day,  respectively, in
dogs (Mullison 1966).274
  Terata and embryo toxicity  effects from 2,4,5-T were
evidenced by statistically increased proportions of abnormal
fetuses within  the  litters of mice and rats (Courtney et al.
1970).254 The rat appeared to be more sensitive to  this
effect. A dosage of 21.5 mg/kg produced no harmful effects
in mice, while a level  of 4.6 mg/kg  caused  minimal  but
statistically significant  effects in the rat. More recent work
has  indicated that  a  contaminant  (2,3,7 ,8-tetrachloro-
dibenzo-p-dioxin)  which was present  at approximately 30
ppm in  the 2 ,4,5-T formulation originally tested was highly
toxic to experimental  animals and  produced  fetal  and
maternal toxicity at levels as low as 0.0005 mg/kg. However,
highly  purified  2,4,5-T  has  also  produced teratogenic
effects in both hamsters and rats at relatively high dosage
rates  (FDA and  NIEHS  unpublished data,™1 Collins  and
Williams 1971252). Current production samples of 2,4,5-T
that contain less than  1  ppm of dioxin did  not produce
embryo  toxicity or  terata in rats at  levels as high  as 24
mg/kg/day (Emerson et al. 1970).261

  Because of possible adverse physiological effects
and  because  there  are  inadequate data  on the
effects of the defined treatment process  on removal
of  chlorophenoxy herbicides, it is recommended
that 2,4-D not exceed 0.02 mg/1, that Silvex not
exceed  0.03  mg/1,  and  that 2,4,5-T  not exceed
0.002 mg/1 in public water supply sources.

  The pH of a raw water supply is significant because it
affects water treatment  processes  and may contribute to
corrosion of waterworks structures, distribution lines, and
household plumbing fixtures. This corrosion can add such
constituents as iron, copper, lead, zinc,  and cadmium to
the water. Most natural waters have pH values within the
range of 5.0 to 9.0. Adjustment of pH within this range is
relatively  simple, and the variety of anticorrosion pro-
cedures currently in use make it unnecessary to recommei
a more narrow range.
  Because the defined treatment process can co]
with natural waters within the pH range of 5.0 1
9.0 but  becomes less economical as  this range
extended, it is recommended that the pH of publ
water supply sources be within 5.0 to 9.0.
                                        PHENOLIC  COMPONDS
  Phenolic compounds  are  defined  (Standard Methods
1971)301 as hydroxy derivatives of benzene and its condensed
nuclei. Sources of phenolic compounds are industrial waste
water discharges (Faust and Anderson  1968),292 domestic
sewage (Hunter  1971),296 fungicides and pesticides (Frear
1969),294  hydrolysis and chemical oxidation  of organo-
phosphorus pesticides (Gomaa  and  Faust  1971),295  hy-
drolysis and photochemical oxidation of carbamate pesti-
cides  (Aly and  El-Dib 1971),289 microbial degradation ol
phenoxyalkyl acid  herbicides (Menzie 1969),298 and natur-
ally occurring substances (Christman and Ghassemi 1966).291
Some  phenolic  compounds  are  sufficiently resistant to
microbial degradation to be transported long distances by-
  Phenols affect  water quality in many ways. Perhaps the
greatest effect is noticed in municipal water systems where
trace  concentrations of phenolic compounds (usually less
than  1.0  mg/1)  affect the organoleptic properties of the
drinking water. For example, p-cresol has a threshold order
concentration of 0.055  mg/1, m-cresol  0.25  mg/I,  and
o-cresol 0.26  mg/1 (Rosen et al. 1962).300  Phenol has a
threshold  odor  concentration of 4.2 mg/1  (Rosen et al.
1962),300 whereas the values for the chlorinated phenols are:
2-chlorophenol,  2.0 jag/l; and  4-chlorophenol,  250 jug/1
(Burttschell et al. 1959).290 Generally, phenolic compounds
are not removed efficiently by the defined treatment procei
Furthermore, municipal waters are postchlorinated to insu
disinfection. If phenolic  compounds are present in wate
that are chlorinated for disinfection, chlorophenols may 1
formed. The kinetics of this reaction are such that chlor
phenols may not appear  until the water  has  been di
tributed from the treatment plant (Lee and Morris 1962).!
  2,4-dinitrophenol has been shown to inhibit oxidatr
phosphorylation  at  concentrations  of  184  and  278  mg
(Pinchot 1967).299
  The development of criteria for  phenolic compounds
hampered by the lack of sensitive standard analytical tec]
niques for  the detection of specific phenolic compound
Some of the more odorous compounds are the para subsl
tuted  halogenated phenols. These escape detection by tl
methodology suggested by  Standard Methods (1971)301 ui
less the analytical conditions are  precisely set (Faust et a

  Because the defined  treatment process may s«
verely increase the odor  of  many phenolic  com
pounds, it is recommended that public water su[
ply sources contain no more than 1 yg/1  phenoli

   Recommendations  for  phosphate  concentrations have
 been considered  but  no generally  acceptable recommen-
 dation is possible at this time because of the complexity of
 the problem. The purpose of such a recommendation would
 be twofold:

   1.  to avoid problems associated with algae and  other
 aquatic plants, and
   2.  to avoid coagulation problems due  particularly  to
 complex phosphates.

   Phosphate is essential to all  forms  of life.  In efforts  to
 limit the development of objectionable plant growths, phos-
 phate  is often considered the  most  readily  controllable
 nutrient. Evidence  indicates (a) that high  phosphate con-
centrations  are associated  with eutrophication of waters
 manifest in unpleasant algal or other aquatic plant growths
when other growth-promoting  factors are favorable; (b)
that aquatic plant problems develop in  reservoirs or other
standing waters at phosphate values lower than those critical
 in flowing  streams; (c)  that reservoirs and other  standing
waters will collect  phosphates  from influent  streams and
store a portion of these  within the consolidated sediments;
and (d) that initial concentrations of phosphate that stimu-
late noxious plant growths vary with other water quality
characteristics, producing such growths in one geographical
area but not in another.
  Because the ratio of total phosphorus (P)  to that form  of
phosphorus readily available for plant growth is constantly
changing and ranges from two to 17 or more times greater,
it is desirable to establish limits  for total  phosphorus rather
than to the portion that may be available for immediate
plant use. Most relatively uncontaminated lake districts are
known to have surface  waters that contain 10 to 30 ng/l
total phosphorus as P; in some waters that are not obviously
 polluted,  higher values may occur. Data collected  by the
 Federal Water Pollution Control Administration, Division
 of Pollution  Surveillance,  indicate that total phosphorus
 concentrations exceeded 50 jug/1 (P) at 48 per cent of the
 stations sampled across the nation  (Gunnerson  1966).302
 Some potable surface water supplies now exceed  200 /ug/1
 (P) without experiencing notable problems due to aquatic
 growths.  Fifty micrograms per liter  of total phosphorus
 (as P)  would probably  restrict  noxious aquatic  plant
 growths in flowing waters and in some standing waters.
 Some lakes, however, would experience algal nuisances at
 and below this level.
  Critical phosphorus  concentrations  will vary with other
 water quality characteristics. Turbidity and  other  factors
 in many of the nation's waters  negate the algal-producing
 effects of high phosphorus concentrations. When waters are
 detained in a lake  or  reservoir, the resultant phosphorus
 concentration is reduced to some extent over that in influent
 streams by precipitation or  uptake by organisms and subse-
 quent  deposition in fecal  pellets  or  the bodies  of dead
 organisms. At concentrations of complex phosphorus on the
 order of 100  Mg/1, difficulties with coagulation are experi-
 enced  (U.S.  Department  of the  Interior,  Federal  Water
 Pollution  Control Administration 1968).303 (See the dis-
 cussion of Eutrophication and Nutrients in Section I for a
more complete description  of phosphorus associations with
 the enrichment problem.)

  No recommendation can be made because of the
complexity  of  relationships  between  phosphate
concentrations in water,  biological productivity,
and resulting problems  such as odor and nitration

                                            PHTHALATE  ESTERS
  Large quantities of phthalate esters are used as plasticizers
in plastics. Phthalates in water, fish, and other organisms,
represent a potential but largely unknown health problem.
They have been implicated in growth retardation, accumu-
lation,  and chronic  toxicity, but  little  conclusive infor-
mation is available (Phthalates are discussed in Section III,
Freshwater  Aquatic Life and  Wildlife.)  Because there
insufficient information on Iheir specific effects on man, i
scientifically defensible recommendation  can be  made
this time concerning concentrations of phthalate esters
public water supply sources.
  The quality of public water supplies may be drastically
affected by the presence of planktonic organisms. Plankton
may be defined as a community of motile or nonmotile
microscopic plants and animals that are suspended in water.
The species  diversity and density of the plankton  com-
munity are important  water  quality characteristics  that
should be monitored  in all public water supplies.  Several
methods for counting  plankton  have  been  improvised.
Many  reports count plankton as number of organisms per
aliquot of sample rather than biomass. Since various species
of algae are  much larger than  other  species, plankton
counts that simply enumerate cells, colonies, or filaments do
not indicate  accurately  the true  plankton  content of the
water (Standard Methods 1971).305
  Plankters are primarily important in public water supply
sources for their contribution to taste and odor problems,
pH alteration,  or  filter clogging.  To aid operators in in-
terpreting  plankton data, the algae counted  should be
listed under applicable  categories that show the predomi-
nance  or  absence of  certain  groups  of  organisms at any
given time. The categories used should include green algae,
blue-green algae,  diatoms,  flagellated  forms, Protozoa,
microcrustaceans and Rotifera, as well as related  Protista.
  Data from plankton counts can be very useful to water
treatment operators (Silvey et al.  1972).304 Counts of blue-
green algae which exceed 50 per cent of the total plankton
community usually indicate potential taste and odor pro!
lems. So long as the  green algae  comprise 75 per cent
the total plankton count, it is not likely that serious tas
and odor problems will arise. The diatom population of tt
plankton community is also important. During some diato:
blooms, the pH of the water increases enough to require tt
addition of more alum  or  iron than would  normally  t
used to achieve  the desired pH in the distribution systen
Some blooms of planktonic  green algae cause  the  pH -
the water to  rise from 7.6  to as high as 10. There are  a]
parently no plankters that  tend to  reduce pH  or remox
minerals in sufficient quantities to alter conditions.
  The role which plankton plays  in the productivity of
lake or reservoir is  important.  The relationship be twee
productivity  and respiration may  frequently be  used as
pollution  index. In many instances, plankton studies  ai
more revealing  than  bacterial studies.  A ratio of produi
tivity to respiration amounting to one or  more  indicati
that the algae are  producing more oxygen than is beir
consumed by the bacteria. If the ratio drops below one fc
significant periods, an undesirable condition exists that ma
cause problems  with anaerobic organisms.  For further di
cussions of productivity  and its relation to water qualit;
see Section I on Recreation and Aesthetics, Section  III  c
Fresh Aquatic Life and Wildlife, and Section IV on Marir
Aquatic Life and Wildlife.

                                POLYCHLORINATED BIPHENYLS  (PCB)
   Polychlorinated biphenyls (PCB)  consist of a mixture of
compounds only  slightly soluble in water; highly soluble
in fats,  oils, and nonpolar liquids; and highly resistant to
both  heat  and biological degradation. PCB have a wide
variety  of  industrial uses, primarily as insulating fluid in
electrical and heat transfer equipment (Interdepartmental
Task  Force 1972).311
   Exposure to PCB is known to cause skin lesions (Schwartz
and Peck  (1943)320 and to increase liver enzyme activity
that may have a secondary effect on reproductive processes
(Risebrough et al. 1968,317 Street et al. 1969,m Wassermann
et al.  1970325). It is not clear at this time whether the effects
are due to PCB or its contaminants, the chlorinated di-
benzofurans that are highly toxic  (Bauer  et  a]. 1961,307
Schulz 1968,319 Verrett 1970324). It is also not known whether
the chlorinated dibenzofurans are produced by degradation
of PCB  as well as during its manufacture.
  The occurrence of PCB in our waters has  been docu-
mented  repeatedly (New Scientist 1966,316  Holmes  et al.
1967,310  Risebrough et al.  1968,317  Jensen  et  al. 1969,312
Koeman et al.  1969,313 Schmidt et  al. 1971,318 Veith and
Lee  1971323).  They  have  been associated  with  sewage
effluents (Holden  1970,3M Schmidt et al.  1971318) and rain-
water (Tarrant and Tatton 1968),322 as well as releases and
leakage. Failures of closed systems using PCB have caused
some  of the more well known releases  (Kuratsune et al.
1969,314  Duke et al. 1970308). It has been reported that the
defined  treatment process does little or nothing to remove
PCB (Ahling and Jensen  1970).306
  An  epidemiological study on severe poisoning by rice oil
contaminated with polychlorinated biphenyls in 1968 indi-
cated that about 0.5 grams ingested over a period of ap-
proximately one month was sufficient  to cause the Yusho
disease. Many of those affected showed no signs of relief
after  about three years (Kuratsune  et al.  1969).314 Price
and Welch (1971)316 have estimated on  the  basis of 194
samples that 41 to 45 per cent of the  general population of
the U.S.  may have PCB levels of  1.0 mg/kg or higher
(wet weight) in  adipose tissue.  Therefore, it appears that
PCB may accumulate in the body. On this basis it can be
calculated  that a daily intake  of 0.02 mg would require
about 70 years to be toxic.  Applying a factor of safety of
10 would permit a daily intake  of 0.002 mg, and assuming
a two liter per day intake, suggests a permissible concen-
tration in  water to be 0.001 mg/1.
  However, evaluation of the retention and accumulation
of PCB from water instead of oil in humans is highly desir-
able. A study on rats with a single oral dose of 170 mg/kg
showed urinary  excretion (of  PCB)  to be limited, while
70 per cent of the dose was found in the feces during an
eight week period (Yoshimura et al.  1971).326 Information
on PCB in the diet would also be helpful.


  Because too little is known about  the levels  in
waters,  the  retention  and accumulation in  hu-
mans, and the effects of very low rates of ingestion,
no defensible recommendation can be made at this

  The effects of radiation on human beings are viewed as
harmful, and any unnecessary exposure to radiation should
be avoided. The U.S. Federal Radiation Council* (1961a)329
provided guidance for federal  agencies to limit exposure of
individuals to  radiation from  radioactive materials in the
environment. The following statement by the U.S. Federal
Radiation  Council (I960)328 is considered especially perti-
nent in applying the recommendations of this report:
    There can be no single permissible or acceptable level
    of exposure without regard to the reason for permitting
    the exposure. It should be general practice to reduce
    exposure to  radiation, and  positive effort  should  be
    carried  out  to fulfill  the sense of these recommen-
    dations. It is basic that exposure to radiation should
    result  from a real determination of its necessity.

  The  U.S.  Federal Radiation Council criteria (I960,328
196la329) have  been used in establishing the limits for radio-
activity recommended  here. It should be noted that these
guidelines  apply to normal peacetime operations. They are
predicated upon three ranges of  daily  intake of radio-
activity as  seen in Table 11-5.
  The recommended radionuclide  intake derives from the
sum of radioactivity from air,  food,  and water.  Daily
intakes  were prescribed with the provision that dose rates
be  averaged over a period of one year.  The  range for
specific radionuclides recommended by the U.S.  Federal
Radiation  Council  (1961b)330 are shown in the following

TABLE  II-5—Ranges of Transient Rates of Intake (pd/day)
            for use in Graded Scale of Action*
                                     TABLE II-6—Graded Scale of Action
                    Ranee I
Range II
Ranie HI
Strontium-90 . .
 » See Table 11-6.
 b In the case of iodine-131, the suitable sample would include only small children. For adults, the radiation protec-
tion guide for the thyroid would not be exceeded by rates of intarin higher by a factor of 10 than those applicable
to small children.
                           Ranges of transient rates of daily intake
                          Range I  .
                          Range II.
                          Range III
                                                             Graded scale of action
                                   . Periodic confirmatory surveillance as necessary
                                   . Quantitative surveillance and routine control
                                    Evaluation and application of additional control measures as nee
  * The functions of the U.S. Federal Radiation Council have been
transferred to EPA, Office of Radiation Programs.
  For each range, a measure of control was defined, whic
represented a graded scale of control procedures.
  The U.S. Federal Radiation Council (1961b)330 furtht
defined the  action to be taken by  stating that "Routir
control  of  useful  applications of radiation and  atom
energy should be such that expected average exposures (
suitable samples of an exposed population group  will nr.
exceed the  upper value of Range II." Furthermore, the
recommended, with respect to Range III,  that "Contn
actions would be designed to reduce the levels to Range I
or lower, and to provide staoiJity at  lower levels."
  It has not been considered necessary to prescribe criteri
for iodine-131 or strontiurn-89 for surface waters. Iodine-13
has never been a problem  in  water supplies and does nc
appear likely to be, and strontium-89 levels should not 1;
significant if strontium-90 levels are  kept satisfactorily lov
Using the  midpoint of Range  I,  Table II-5, for transier
rates of intake recommended by the U.S. Federal Radiatio
Council, and assuming a 2 liter per day  consumption, th
radium-226 limit is 0.5 Pc/day and strontium-90  limit
5 Pc/day. These levels are not  currently being exceeded i
any surface water supply in the United States,  although
number of ground water supplies have more than 0.5 pCi/
of radium-226.
  Because tritium  (hydrogen-3)  may be  discharged fror
nuclear power reactors  and fuel reprocessing plants,  an
because it would not be detected  in normal  analysis c
water samples, it has been  considered desirable to  includ
a limit on this low energy radionuclide. The Federal Radi
ation Council has not provided guidance on tritium intake
A tentative limit of 3,000 pCi/1 of tritium has been propose*
for the revised edition of Drinking Water Standards. Thi
relatively conservative limit has been  suggested because c

                                                                                                     Radio'activity /85
uncertainty in the potential  genetic effects of tritium in-
corporated  into  body  tissues as tritiated water.  It  is a
generally attainable level based on data from the Environ-
mental Protection Agency Tritium Surveillance System.
These data indicate that of 70 United States cities surveyed
in 1970, none  had an'annual average  tritium activity in
tap water exceeding 3,000 pCi/1, the highest annual average
value being 1,900 pCi/1. Levels  in surface water collected
downstream from nuclear facilities showed only two of 34
locations  having  tritium  activity exceeding 3,000  pCi/1.
Precipitation samples taken during 1970 at locations within
the United States indicated less than 700 pCi/1.
  Although a large number of other radionuclides may be
present in water, it has not  been considered  necessary to
include specific limits for  other  than the  three mentioned
above. If other nuclides are likely to be present, it is recom-
mended that permissible limits be held to 1/150 of the limit
for  continuous  occupational  exposure  set  by the  Inter-
national Commission on Radiological Protection  (I960).327
  Gross radioactivity limits  provide screening techniques
and guides to an increased level  of radiochemical analysis.
If the gross alpha and gross beta concentrations in a sample
are less than certain minimum concentrations, no additional
radiochemical or radiophysical analyses are required.
  Gross Alpha Radioactivity Gross  alpha  limits  or
investigation levels are keyed  to the concentration limit for
radium-226 (the  alpha emitter  with the most restrictive
intake limit). A typical scheme is the following:

TABLE 11-7—Typical Scheme  of Gross Alpha Concentration
TABLE II-8—Gross Beta Radioactivity to Strontium-90 and
                 Isotopes of Radioiodine
      Gross Alpha concentration (pCi/1)
                                       Required action
(a) Not exceeding 0.5 pCi/1	None
(b) Greater than 0.5 but not exceeding 5 pCi/1	Radiochemical analysis for radium-226
(c) Greater than 5 pCi/1	 Comprehensive radiochemical anaylsis
  Gross Beta Radioactivity  Two beta emitting radio-
nuclides with the  most  restrictive maximum permissible
concentrations are  lead-210 and  radium-228. However,
since it is extremely unlikely that  either radionuclide will
  Gross Beta concentration excluding Potassium-40
                                       Required action
(a) Not greater toi 5 pCi I
(b) Greater than 5, but less than 50 pCi/1
(c) Greater than 50 pCi/1. .
. None (with knowledge that lead-210 and radium-228
  are essentially absent)
. Analyses for strontium-90, iodine-) 29, and iodine-131
 Comprehensive radiochemical analysis
ever be  present  in  a significant concentration in  a raw
water source, the investigation levels for gross beta radio-
activity are keyed to strontium-90 and isotopes of radio-
  The radionuclide concentration limits  proposed  in  the
above tables should not be considered as absolute maxima
that,  if  exceeded, constitute  grounds for  rejection of a
drinking water supply source.  Instead, the concentration
limits should  be  considered guidelines that should not be
exceeded unless there is good reason. The  constraints that
should be imposed are based on: (1) a determination by the
appropriate regulatory  agencies  that the  higher level  of
radioactivity is as low as can be practicably achieved, and
(2)  quantitative   surveillance  of all  intake pathways  to
demonstrate that total  dose to a suitable sample  of  the
exposed  population  is within Radiation Protection Guide-
lines levels. To  permit  variances in radionuclide concen-
trations  in  water depending  on concentrations in  other
environmental media  and dietary habits is consistent with
the guidance and recommendations  of the  U.S. Federal
Radiation  Council, the National Council on  Radiation
Protection  and Measurement,  and the International  Com-
mission on Radiological Protection.

  Because the defined treatment process has un-
certain effects  on  the  removal of soluble  radio-
nuclides and because of the effects of radiation on
humans,  it is recommended that the limits related
to  the guidelines presented  above  be accepted in
the context of the discussion  for application to
sources of public water supply.

  The toxicity of selenium  resembles that of arsenic and
can, if exposure is sufficient, cause death. Acute selenium
toxicity is characterized by  nervousness, vomiting, cough,
dyspnea,  convulsions,  abdominal pain, diarrhea,  hypo-
tension, and respiratory failure. Chronic exposure leads to
marked pallor,  red  staining of  fingers, teeth and  hair,
debility, depression, epistaxis, gastrointestinal disturbances,
dermatitis, and  irritation of the nose  and throat.  Both
acute and chronic exposure  can cause odor on the breath
similar to garlic (The Merck Index of Chemicals and Drugs
1968).836 The  only documented case  of selenium toxicity
from a water source, uncomplicated with selenium  in  the
diet, concerned a three-month exposure  to well water con-
taining 9 mg/1 (Beath 1962).331
  Although previous evidence suggested that selenium was
carcinogenic (Fitzhugh  et al. 1944),332  these observations
have not  been borne out by subsequent data (Volganev
and  Tschenkes  1967).346  In recent years,  selenium  has
become recognized as a dietary essential in a  number of
species (Schwarz  I960,341 Nesheim and Scott 1961,338 Old-
field et al. 1963339).
  Elemental selenium is highly insoluble and requires oxi-
dation to selenite or selenate before appreciable quantities
appear in water  (Lakin and Davidson  1967).335 There is
evidence that  this reaction  is catalyzed by  certain  soil
bacteria (Olson 1967).340
  No systematic investigation of  the forms of selenium in
excessive concentrations in drinking water sources has been
carried out. However, from what is known of the solubilities
of the various compounds of selenium,  the principal in-
organic compounds  of selenium would be selenite  and
selenate. The ratio of their  individual occurrences  would
depend  primarily  on pH. Organic  forms of selenium  oc-
curred in  seleniferous soils and had sufficient mobility in
an aqueous environment to be preferentially absorbed over
selenate in certain plants (Hamilton  and Beath  1964).334
However, the extent to which these compounds might occi
in source waters is essentially unknown. Toxicologic exam
nation of plant sources of selenium revealed that seleniui
present in seleniferous grains was more toxic than inorgani
selenium added to the diet (Franke and Potter 1935).333
   Intake of selenium from foods in seleniferous areas (Smit
1941),342 may range from 600 to 6,340 jug/day,  which ap
proach estimated levels related to symptoms  of seleniur
toxicity in man  based on urine  samples  (Smith et  a
1936,343 Smith and Westfall  1937344). If data on seleniur
in foods (Morris and Levander 1970)337 are applied to th
average consumption  of foods (U.S. Department of Agri
culture, Agriculture Research Service, Consumer and Fooi
Economics Research Division 1967),345 the normal  dietar
intake of selenium is about 200 fig/day.
   If it is assumed that two liters of water are ingested pe
day, a 0.01 mg/1 concentration of total selenium wouL
increase the normal total dietary intake by  10 per cen
(20 jug/day). Considering the  range of  selenium in fooi
associated with symptoms of toxicity in  man,  this woulc
provide a  safety factor of from 2.7 to 29. A serious weaknes
in these calculations is that  their  validity depends on  ai
assumption of equivalent  toxicity of selenium  in food an<
water, in  spite of the  fact that a  considerable  portion c
selenium  associated with plants is  in an  organic form
Adequate toxicological data  that specifically examine th
organic and  the  inorganic selenium compounds are  no

   Because the defined  treatment process has litth
or no effect on removing selenium, and  because
there is a lack of data on its toxic effects on human!
when ingested  in water, it is recommended that
public water supply sources contain no more than
0.01 mg/1 selenium.

  Silver  is a rather rare element with a low solubility of
0.1  to  10 mg/1 depending upon pH and chloride concen-
tration (Hem  1970).348 Data from 1,577 samples collected
from  130 sampling points in the  United States showed
detectable (0.1 /ig/1) concentrations in 104 samples ranging
from  1.0  to 38  /ug/1  with a median of 2.6 jug/1  (Kopp
  The principal effect of silver in the body is cosmetic. It
causes  a  permanent grey discoloration of skin, eyes, and
mucous membranes. The amounts of colloidal  silver re-
quired to produce this condition (argyria, argyrosis), which
would  serve as a basis for determining the water standard,
are not known; but  the  amount of silver  from injected
agarsphenamine that  produces  argyria  is any amount
greater than one gram of silver in the adult (Hill and
Pillsbury  1939,349 1957360). It  is also reported that silver,
once absorbed, is held indefinitely in the tissues (Aub and
Fairhall 1942).347
  A study that  provided analyses of samples  of human
tissues from 30 normal adult males showed three to contain
silver in minute amounts. Comparison of the mean daily
concentrations of silver in successive daily samples of urine,
feces, and food (0.088 mg/day)  showed essentially  no ab-
sorption of the intake from  food (Kehoe et al.  1940b).351
Studies  of the metabolism of silver in the rat showed only
about 2 per cent of the element entered the blood from the
gastrointestinal tract and  that the biological half life was
about 3 days (Scott 1949).363 However, this work was done
with carrier free silver and may not be representative of the
behavior of larger  amounts of  element. It does suggest,
however, that ingested silver is not likely to be completely
stored in the  body.


  Because  silver in  waters  is rarely detected at
levels above 1 /ug/1, a limit is not recommended for
public  water supply sources.

  Sodium salts are ubiquitous in the water environment.
These minerals are highly soluble, and their concentrations
in natural  waters show considerable variation, regionally
and locally. In addition to natural sources of sodium salts,
other sources are sewage, industrial effluents, and deicing
salts.  Sodium concentrations  in  ground waters may also
vary with  well  depth,  and  often reach higher levels of
concentration than in surface waters.  Removal of sodium
is costly and is not common  in public water supply treat-
  Of the 100 largest public water supplies in the U.S., most
of which are surface supplies, the median  sodium content
was 12 mg/1 with a range of 1.1 mg/1 to 177 mg/1 (Durfor
and Becker  1964).365  For  a healthy  individual, the intake
of sodium is discretionary and influenced by food selection
and seasoning. The intake of sodium may average 6 g/day
without adverse effects on health (Dahl I960).354
  Various restricted sodium intakes are recommended by
physicians for a significant portion of the population,  in-
cluding persons suffering from hypertension,  edema associ-
ated with  congestive cardiac failure,  and  women  with
toxemias of pregnancy (National  Research Council,  Food
and  Nutrition  Board 1954).386 The sodium intake  from
sources other than water recommended for very restricted
diets is 500  mg/day. Diets  for  these  individuals  permit
20 mg/1 sodium in  drinking  water and  water used  for
cooking.  If the public water  supply has a  sodium content
exceeding this limit,  persons on a very restricted sodium
diet must use distilled or deionized water.
  For a larger portion of the  population who use a moder-
ately  restricted diet,  1,000 mg/day  is the recommended
sodium intake limit (National Research Council, Food and
Nutrition Board 1954).356 Under this limit, water containir
a  higher concentration of sodium  could be  used if  tt
sodium intake from the sources  other than water were  n<
increased above that of the very restricted diet, Then,  tf
daily intake of sodium from water  (20  mg/1 for very n
stricted diets) could be increased by the additional 500 m
(250 mg/1)  intake permitted in the moderately restricte
diet, thus allowing a significant portion of the  populatio
to use public  water  supplies with higher sodium concer
trations. On this basis water containing more than 270 mg,
sodium should not be  used for drinking water by  thos
using the moderately  restricted sodium diet,  and wate
containing more than 20 mg/l sodium should not be use
by those using the very restricted sodium diet.
   The response of people who should restrict their sodiur
intake for  health reasons  is  a continuum  varying wit
intake.  The allocation of the difference in dietary intak
allowed by the very restricted and the moderately restricts
diets  to drinking  water would  be an  arbitrary decision
Furthermore,  waters containing  high  concentrations  c
sodium (greater than 270 mg/1) are likely to be too high]-
mineralized to be considered desirable from aesthetic stand
points aside from health considerations.
   Treatment of an entire  public water  supply to  remov
sodium is quite costly.  Home treatment for drinking wate
alone for those needing low sodium water can be done a
relatively modest cost, or low sodium content bottled wate
can be used.

   In view of the above discussion no limit is recom-
mended for sodium.

  The public water supplies of the 100 largest cities in the
United States were found to contain a median sulfate con-
centration of 26 rng/1, and a maximum of 572 mg/1 (Durfor
and Becker  1964).387 Greater concentrations were present
in many ground  water supplies for smaller communities
in the Midwest (Larson 1963).358 Sulfate ions in drinking
water can have a cathartic effect on occasional  users, but
acclimatization is rapid. If two liters of water are ingested
per day,  the equivalent sulfate concentrations for laxative
doses of  Glauber  salt and Epsom  salt are 300  mg/1 and
390 mg/1, respectively (Peterson  1951,361 Moore  1952360).
  Data collected by  the North Dakota  State Department
of Health on laxative effects of  mineral quality in water
indicated that  more than 750 mg/1 sulfate had  a laxative
effect,  and less  than  600 mg/1 did not (Peterson 1951).361
If the water was high in magnesium,  the effect took  place
at lower  sulfate concentrations than if other cations were
dominant. A subsequent interpretation showed that laxative
effects were experienced by sensitive persons not accustomed
to the water when magnesium was  about 200 mg/1, and
by the average person when magnesium was 500-1000 mg/1
(Moore 1952).360
  The median of sulfate concentrations detected by taste
by a panel of 10 to 20 persons was 237, 370, and 419 mg/1
for  sodium, calcium,  and  magnesium salts,  respectively
(Whipple 1907).362 Coffee brewed with 400 mg/1  sulfate
added as magnesium sulfate was affected in taste (Lockhart
et al. 1955).859

  On the basis of  taste and laxative effects and
because  the defined  treatment process  does  not
remove sulfates, it is recommended that sulfate
in public water supply sources not exceed 250 mg/1
where  sources with  lower sulfate concentrations
are or can be made available.
  Temperature affects the palatibility of water by intensi-
fying  taste and odor  through increased volatility of the
source compound (Burnson 1938).366 Any increase in tem-
perature may stimulate growth of taste and odor producing
organisms (Kofoid 1923,372 Thompson 1944,378 Silvey et al.
1950377) but tends to decrease the survival time of infectious,
organisms (Peretz and Medvinskaya 1946,376 Rudolfs et al.
1950376).  The  standard treatment process is also affected
by temperature  or  temperature changes in the steps of
coagulation (Velz 1934,379 Maulding and Harris 1968,373
American Water Works Association 1971363), sedimentation
(Camp et al.  1940,36S Hannah et al.  1967370), filtration
(Hannah et al. 1967370), and chlorination (Ames and Smith
1944,3M Butterfield and Wattie 1946367).
  Temperature changes usually are caused by using water
as a  coolant, as a  carrier of wastes,  or  for  irrigation
(Brashears, Jr. 1946,366 Moore 1958,374  Eldridge  I960,369
Hoak 1961371). Surface water temperatures  vary with the
seasons, geographical location, and climatic conditions. The
same factors along with geological conditions affect ground
water temperatures.

  No temperature change that detracts from the
potability of public water supplies and no  temper-
ature change that adversely  affects the standard
treatment  process  are suggested  guidelines for
temperature in public water supply sources.

                                       TOTAL  DISSOLVED  SOLIDS
                                               (Filterable Residue)
  High total dissolved solids (TDS) are objectionable be-
cause of possible physiological effects, mineral taste, and
economic consequences. Limited research (Bruvold 1967380)
indicated that consumer acceptance of mineralized waters
decreased in direct proportion to increased mineralization.
This study  covered a range of TDS values of 100 to 1,200
mg/1; one at 2,300 mg/1 TDS. For high levels of minerali-
zation,  there may also be a  laxative effect,  particularly
upon transients. High concentrations of mineral salts, par-
ticularly sulfate and chloride, are also associated with costly
corrosion damage in water systems (Patterson and Banker
  Because of the wide range of mineralization of natural
water,  it is not  possible to establish a single limiting value.
The measurement of specific conductance provides an indi-
cation  of the amount of TDS  present. The relationship of
specific conductance to TDS will vary depending upon the
distribution of the major constituent elements present. For
any given water a relatively uniform relationship will exist.
Where sufficient data exist to establish a correlation between
the two measurements, specific conductance may be use
as a substitute for the TDS measurement. In very gener
terms,  a specific  conductance of 1,500 micro-rnhos  is aj
proximately  equivalent  to 1,000 mg/1 TDS  (Standai
Methods 1971).383
  Because drinking water containing a high concentratic
of TDS is likely  to contain an excessive concentration i
some specific substance thai: would be aesthetically  objei
tionable to the consumer, the 1962 Drinking Water Stanc
ards (PHS  1962)382 included a limit  for TDS of 500 mg/
if other less mineralized sources were  available. Althoug
waters of higher concentrations are not generally desirabli
it  is recognized  that a  considerable number  of supplit
with dissolved solids in excess of the 500 mg/1 limit are use
without any obvious ill effects. Therefore, instead of recorr
mending a general dissolved solids limit, specific recommer
dations are made in this report for individual substances (
importance in drinking water sources, such as chloride an
  The recommendation for acceptable levels  of turbidity
in water must relate to the capacity of the water treatment
plant to remove turbidity adequately and continuously at
reasonable cost. Water treatment plants are  designed to
remove the kind and  quantity of turbidity to  be expected
in each water  supply source.  Turbidity can reduce  the
effectiveness of chlorination by physically protecting micro-
organisms from direct contact with the disinfectant (Sander-
son and Kelly 1964,384 Tracy et al. 1966).386
  Customary  methods (Standard  Methods  1971)385  for
measuring and reporting  turbidity do not  adequately
measure those characteristics harmful to public water supply
and water treatment processing. A water with 30 turbidity
units may coagulate more rapidly than one with  5 or 10
units. Conversely, water with 30 turbidity units sometimes
may be more difficult to coagulate than water with  100
units. The type of plankton, clay, or earth  particles, their
size, and electrical charges, are more important determinin
factors than the turbidity units. Sometimes clay added t
very low turbidity water will improve coagulation.
  Turbidity  in  water  should be  readily  removable  b
coagulation, sedimentation, and filtration; it should not b
present to an extent that will overload the water treatmen
plant  facilities; and it should  not cause unreasonable treat
ment  costs.  In addition, turbidity should  not  frequent!'
change or vary  in characteristics  to the extent that sue!
changes cause upsets in water treatment plant processes.

  No  recommendation  is made, because  it is no
possible to establish  a  turbidity recommendatioi
in  terms  of turbidity units;  nor can a turbidity
recommendation  be  expressed in terms of  mg/
"undissolved solids" or "nonfilterable solids."

                                                 URANYL  ION
   The  1968 edition  of Water Quality Criteria (FWPCA
 1968)387 included a limit for uranyl ion (UO2++) of 5mg/l,
 because a  1965 Public Health Service  Drinking  Water
 Standards Review  Committee had  tentatively  decided  to
 include it in the next revision of the Drinking Water Stand-
 ards. This value was selected because it  is below the ob-
jectionable  taste and appearance  levels  as well as the
 chemically toxic concentration.
   Further investigation of raw water quality data indicated
 that  uranium  does not occur  naturally  in  most waters
 above a few micrograms per liter (U.S. Geological Survey
 1969,388 EPA office memorandum 1971389).


   The  taste,  color,  and gross alpha  recommen-
 dations will restrict  the uranium concentration to
 levels  below  those objectionable  on  the  basis of
 toxicity. For  these reasons, no specific limit is pro-
 posed for uranyl ion.
  Many types of viruses  are excreted in the wastes  of
humans and animals (Berg 1971392),  and some  have been
implicated in diseases (Berg 1967391). There are'viruses that
alternate between animal hosts (Kalter 1967)403 and those
that can  infect  genetically distant  hosts (Maramorosch
1967).407 Because almost any virus can be transmitted from
host to host through water (Mosley  1967),409 any amount
of virus detectable  by  appropriate techniques  in  surface
water supplies constitutes a hazard (Berg  1967).391
  While it is believed that all human enteric viruses have
the potential to  cause  illness in  man, not all have been
etiologically associated  with clinical  illness.  A number  of
waterborne local  outbreaks attributed to virus affecting
approximately  800  people  have  occurred in the  United
States, but no obvious large scale spread  of a viral disease
by  the water route is  known to have occurred  (Mosely
1967).409 Although virus transmission by water has been
suggested  for  poliomyelitis, gastroenteritis, and diarrhea,
the most  convincing documentation  exists  for infectious
hepatitis (Mosley 1967).409 Twelve outbreaks of infectious
hepatitis have  been attributed to  contaminated drinking
water  in the United States between  1895 and  1971, and
most of these have been linked to private  systems.
  Berg (1971)392 suggests that waterborne viral disease need
not occur at the epidemic level in order to be of significance.
Small numbers of virus  units could produce infection with-
out causing overt disease,  and infected individuals could
then serve  as sources of larger amounts of virus.
  The interpretation of virus data presents other problems
in addition to those posed by epidemiological evaluation.
There is evidence that one virulent virus unit can be suffi-
cient to  infect man  if  it contacts susceptible cells (Plotkin
and Katz 1967),411 but in an intact host, this is complicated
by  various defenses  (Beard 1967).390 The  interpretation of
data is further complicated by aberrations in survival curves
for  virus thought to  be caused by clumping. The statistical
treatment of virus data has been discussed by Berg et al.
(1967),393 Chang  (1967,395  1968396),  Clark  and  Niehaus
(1967),399 Sharp \1967),412 and Berg (1971).392
  The route of enteric viral contamination of surface waters
is from human feces through the effluents of sewage treat-
ment plants  as  well as contamination from raw sewage.
Enteric virus densities in human feces have been estimated
by  calculation and  sampling. Clarke  and  his associates
(1962)400 suggested that human feces contained approxi-
mately 200 virus units per gram per  capita and 12X106
coliform  bacteria per gram per capita, or  15 enteric  virus
units per 106 coliforms. Combining these calculations with
observed data, they  estimated that sewage contained 500
virus units per 100  ml, and  contaminated surface waters
contained less than 1 virus unit per 100 ml. These numbers
are  subject to wide variation and change  radically during
an epidemic.
  The removal  capabilities of various sewage  treatment
processes have been examined individually  and in series
both in the laboratory and in the field  (Chin et al. 1967,398

^I/Section II—Public Water Supplies

 TABLE H-9—Average  Time  in Days for 99.9 Per  Cent
  Reduction in Original Titer of Indicated Microorganisms
                 at Three Temperatures
   Clean water    Moderately polluted water     Sewage
28 C   20 C   4C   28 C   20 C   4C  28 C   20 C  4C
Poliovirus I . .
ECH0 12 .
Coisackie A9 . .
A. aerogenes
S recalls 	
. . 17
.. . <8
. . 6
... . 6
. ... 6
No data
 Clarke et al. 1962<"

Clark and Niehaus  1967,399  England et al.  1967,402  Lund
and  Hedstrom 1967,404 Malherbe  1967,405 Malherbe and
Strickland-Cholmley  1967,406 Berg 1971392).  These studies
indicated that  while some  sewage treatment processes
showed virus removal potential in laboratory tests and field
evaluation, there was no indication that consistent adequate
virus removal, that is no detectable virus, was accomplished
by present sewage treatment  practices (Berg 1971).392 How-
ever, the apparent limited survival time for viruses in wat<
can be affected by factors, such as temperature and adsor]
tion that protects viruses; and the proximity of water use
may make survival for only a short period of time sufficiei
to transmit virulent  virus (Prier and Riley 1967).41°
  Table II-9 gives  virus  and bacterial  survival data  f<
clean, moderately contaminated, and sewage water.
  The  removal capabilities of  various  water  treatmei
processes are presented in Table 11-10.
  Conventional water treatment processes are variable i
their virus removal efficacy and questionable in their pe
formance under  field conditions  (Berg 1971,392  Sproi
  Disinfection  by chlorination was  reviewed recently  f'<
its virus inactivation efficacy (Morris 1971).408 Only undi
sociated hypochlorous acid (HOC1) was considered effecti\
in virus inactivation. Approximately 25 mg/1 chloramin
100 mg/1 hypochlorite or 0.5 to  1.0 mg/1  HOC1 wi1
30-minute contact times were  required to cause  adequa
viral inactivation in  potable water. The amount of chlorit
required to achieve  these conditions varied with the p.
and the amount of nitrogen present.
TABLE II-10—Removal of Viruses from Water and Wastewater by Biological, Physical, and Chemical Treatment Procedur
                           Menstruum tested (2)
                                             Retention time, m hours ())
                                                                    Virus" (4)
                                                                                Virus removed, as a percentage (5)
                                                                                                       Reference (6)
Primary setting . Primary effluent
Activate d sludge Activated sludge effluent

Carbon adsorption (0. 5 gal per min per sq ft) Trickling filter effluent
Ca(OH)= coagulation (500 mg per 1) Activated sludge effluent
AP(SCH)' coagulation (25 mg per 1) River water
Fed3 coagulation (25 mg per 1) . . . River water

Poliovirus 1
Coxsackievirus A9
Poliovirus 1
. Poliovirus 1
Coxsackievirus A2
Coxsackievirus A2
Clarke etal. 1961<»i
Clarke et al. 1961'°'
Clarke et al. 1961«»
Sproul et al. 1967'"
Berg etal. UBS1"
Chang et al. 1958"'
Chang etal. 1958"'
 « Added to the test experimentally.
 << When volatile solids were at least 400 mg per I.
 'When good floe formation occurred.
  Considerable progress on virological method development
has been made in the past decade. However, virology tech-
niques have not yet been perfected to a point where they
can be used routinely for monitoring water for viruses. There
is a need for virus data on relative numbers, better tech-
niques, relative die-off rates, and correlation with existing
indicators, as well as methods for direct determination.

                                            In view of the uncertain correlation of virus oc
                                          currence with existing  Indicators,  the absence e
                                          adequate monitoring  techniques, and the genera
                                          lack of data, scientifically defensible criteria canno
                                          be recommended at this time.

  Zinc is an essential  and beneficial element in human
metabolism. The  activity of insulin and several body en-
zymes is dependent on zinc. The daily adult human intake
averages  10 to 15 mg; for preschool children it is 0.3 mg/kg.
(Vallee 1957).420
  Zinc is a widely used metal and may be dissolved from
galvanized  pipe,  hot water  tanks, or from  yellow brass.
It may also be present  in some corrosion prevention addi-
tives and in  industrial wastes.  The solubility  of zinc is
variable,  depending upon pH and alkalinity.
  In 1,577 samples from 130 locations on streams between
October  1962 and September  1967,  zinc  was detected
(2 Mg/1)  in 1,207  samples with a range of 2  to  1,183 pig/1
and a mean of 64 Mg/1  (Kopp  1969).419
  Individuals drinking  water  containing 23.8 to 40.8 mg/1
of zinc experienced no known  harmful effects. Communities
have reported using water containing 11 to 27 mg/1 of
zinc without  harmful effects  (Bartow  and Weigle 1932,416
Anderson et al. 1934416). Another report stated that spring
water containing 50 mg/1 of zinc was used for a protracted
period without harm (Hinman, Jr. 1938418).
  Statistical analysis of taste threshold tests with zinc in
distilled water showed that 5 per cent of the observers were
able to  distinguish between 4.3 mg/1 zinc (added as zinc
sulfate)  and water containing no zinc salts (Cohen et al.
I960417). When added as zinc nitrate and as zinc chloride,
the detection levels were 5.2 and 6.3 mg/1 zinc, respectively.
When zinc  sulfate or zinc chloride  was  added  to spring
water with 460 mg/1 dissolved solids, the detection levels
for  5 per cent of the observers were 6.8 and 8.6 mg/1 zinc,

  Because of consumer  taste preference and be-
cause the  denned treatment process may not  re-
move appreciable amounts of zinc from the source
of  the supply, it  is recommended  that  the zinc
concentrations in public water supply sources not
exceed 5 mg/1.

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\02/Section II—Public Water Supplies
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                                     TABLE  OF  CONTENTS
        Community Structure	    110
        Protection of Significant Aquatic Species. .    110
          Recommendation	    112
          Recommendation	    112
          Recommendation	    113
          Recommendation	    113
          Recommendation	    114
          Recommendation	    1 HI-
      ZONES	    114
          Recommendation	   115
          Recommendation	   115
    PROGRAMS	   116
    FIELD SURVEYS	   116
    BIOASSAYS	   117
        Species	   119
                                 Dilution Water	
                                 Test Methods	
                                 Dissolved Oxygen	
                                 Evaluation of Results	
                             APPLICATION FACTORS	
                             MIXTURES OF Two OP  MORE TOXICANTS. . .  .
                             SUBLETHAL EFFECTS	
                                 Recommcnations for the Use of Appli-
                                   cation Factors to Estimate Safe Concen-
                                   trations of Toxic Wastes in Receiving
                         PHYSICAL  MANIPULATION  OF  THE  EN-
                         SUSPENDED AND SETTLEABLE  SOLIDS...
                             SOIL As  A SOURCE OF  MINERAL PARTICLES...
                             EFFECTS OF SUSPENDED  PARTICLES IN  WATER. .
                             ADSORPTION OF Toxic  MATERIALS	
                             EFFECTS  ON FISH AND  INVERTEBRATES	
                         DISSOLVED GASES	
                             DISSOLVED OXYGEN	
                                 Levels of Protection	
                                 Basis for Recommendations 	
                                 Warm- and Coldwater Fishes	
                                 Unusual Waters	
                                 Organisms Other Than Fish	    I'.
                                 Salmonid Spawning	    1'
                                 Interaction With Toxic Pollutants or Other
                                   Environmental Factors	
                                 Application of Recommendations	
                             TOTAL DISSOLVED GASES (SUPERSATURATION) ..
                                 Etiologic Factors	
                                 Gas Bubble Disease Syndrome and Effects.
                                 Analytical Considerations	

        Total Dissolved Gas Pressure Criteria  ...    138
          Recommendations	    139
    CARBON DIOXIDE	    139
          Recommendation	    139
          Recommendations	    141
          Recommendation 	    143
OILS	    144
    SEDIMENTED OIL  	    145
          Recommendations	    146
      TERIALS 	    148
      ORGANISMS	    149
        Test Fish	    149
        Exposure Period	    149
        Exposure Conditions	    149
        Preparation of Test Fish and Evaluation..    149
          Recommendations	    150
      LONGED  EXPOSURES	    153
      LONGED EXPOSURE	    154
          Recommendation	    160
    WINTER MAXIMA	    160
          Recommendation	    161
      ATURE 	    161
          Recommendation	    162
          Recommendations	    164
      MUNITIES 	    165
          Recommendation	    165
    CONCLUSIONS	    165
        Analytical Steps	    168
        Aquatic Areas Sensitive to Temperature
          Change	    168
        Cooling Water Entrainment	    168
        Entrainment in the Plume	    170
        Bottom Organisms Impacted by the Plume   170
        Mixed Water Body	    171
        Discharge Canal 	    171
        Biological Methylation	    172
        Biological Magnification	    172
        Mercury in Fresh Waters	    173
        Toxicity of Organic Mercury in Water...    173
        Tissue Levels and Toxicity	    174
        Discussion of Proposed Recommendations.    174
          Recommendations	    174
        Toxicity	    175
          Recommendation	    175
        Direct Lethal Toxicity	    176
        Feeding Studies	    176
        Residues in Tissue	    176
        Effects on Reproduction	    177
        General   Considerations  and   Further
          Needs	    177
        Basis for Recommendations	    177
          Recommendations	    177

METALS	   177
    General Data	   177
      Recommendations	   179
    Aluminum	   179
      Recommendation	   179
    Cadmium	   179
      Recommendation	   180
    Chromium	   180
      Recommendation	   180
    Copper	   180
      Recommendation	   181
    Lead	   181
      Recommendation	   181
    Mercury	   181
      Recommendation	   181
    Nickel	   181
      Recommendation	   181
    Zinc	   182
      Recommendation	   182
    Methods, Rate,  and Frequency of Appli-
      cation	   182
    Sources and Distribution	   182
    Persistence and Biological Accumulation. .   183
    Residues	   183
    Toxicity	   184
    Basis for Criteria	   185
      Recommendations	   185
    Ammonia	   186
      Recommendation	   187
    Chlorine	   189
      Recommendation	   189
    Cyanides	   189
      Recommendation	   190
    Detergents	   190
    Detergent Builders	   191
      Recommendation	   191
        Phenolics	    191
          Recommendations	    191
        Sulfides	    191
          Recommendation	    193
WILDLIFE	    194
      LIFE 	    194
    PH	    194
          Recommendation	    194
    ALKALINITY	    194
          Recommendation	    195
    SALINITY	    195
          Recommendation	    195
          Recommendation	    195
      PLANTS	    195
    TEMPERATURE	    195
          Recommendation	    195
        Direct Acting Substances	    196
          Oils	    196
            Recommendation	    196
          Lead	    196
            Recommendation	    196
          Botulism Poisoning	    196
            Recommendation	    197
        Substances Acting After Magnification in
        Food Chains	    197
          Chlorinated Hydrocarbon Pesticides....    197
            DDT and Derivatives	    197
              Recommendation	    198
            Polychlorinated Biphenyls (PCB)	    198
              Recommendation	    198
          Mercury	    198
            Recommendation	    198

   The biota of a natural aquatic ecosystem is the result of
evolutionary processes  in  the  course  of which a delicate
balance and complex interactions were established among
various kinds of organisms and between  those organisms
and their environment. Some species can live in a wide
range of environmental conditions and are found in many
different systems throughout the world. Other species  are
restricted and their distribution is limited to certain habitats
or in some  cases to only one. Frequently, it is  the latter
group of species that have been most useful to man. Minor
changes in  their environments, especially  if such changes
are rapid, may upset the ecological  balance and endanger
the species.
   Man has  the ability to alter—to impair  or improve—his
environment and that of other  organisms. His use of water
to dispose of wastes of a technological society and his other
alterations of aquatic environments have degraded his water
resources. Water pollutants may alter natural conditions
by reducing the dissolved oxygen content, by changing  the
temperature, or by direct toxic  action that can be lethal or,
more subtly, can affect the behavior, reproduction, and
physiology  of the organisms.  Although a substance may
not directly affect a species, it may endanger its continued
existence  by eliminating  essential  sources  of food and
metabolites.  Furthermore, conditions  permitting  the sur-
vival of a given organism at one stage of its life may be
intolerable at another stage.
   This Section evaluates criteria and proposes recommen-
dations that reflect scientific understanding of the relation-
ships between freshwater aquatic organisms and their  en-
vironment.  Anything added to or  removed  from natural
waters will cause some change  in the system. For each  use
of water there are certain water quality characteristics that
should be met to ensure the suitability of the water  for
that use.
  The following general recommendations  apply to a wide
variety of receiving systems and pollutants:

     • More stringent methods of control or treatment, or
      both, of waste inputs and land drainage should be
      applied  to improve water quality as the demand  for
      use increases.
     • In recognition of the limitations of water quality
       management  programs,  consideration  should  be
       given to  providing reserve  capacity of receiving
       waters for future use.
     • Bioassays and other appropriate tests, including field
       studies, should be made to obtain scientific evidence
       on the effect of wastewater  discharges on  the en-
       vironment. Test  procedures  are recommended  in
       this report.
     • A survey of the receiving system to assess the impact
       of  waste discharges on  the  biological community
       should be made on a regular basis, particularly prior
       to  new  discharges. Such surveys especially should
       cover the seasons  most critical to the biological com-
       munity. Background laboratory data should include
       bioassays using important local aquatic organisms
       and associated receiving waters. In addition to the
       more  comprehensive  surveys,  some  form  of  bio-
       monitoring in the receiving system should be carried
       out routinely. A suggested list of ecological consider-
       ations  is  included in  the section on Biological
     • One  of the principal  goals is to insure the mainte-
       nance of the biological community typical  of  that
       particular locale or, if a perturbed community exists,
       to upgrade the receiving system to  a quality which
       will permit reestablishment of that community.


  The natural aquatic environment includes many kinds of
plants and animals that vary  in their  life history  and  in
their chemical and physical requirements. These organisms
are interrelated in many ways to form communities. Aquatic
environments are protected out of recreational and scientific
interest, for aesthetic enjoyment, and to maintain  certain
organisms of special significance as a source of food. There
are two schools of thought as to how this can be accom-
plished. One is  to  protect the significant  species, the as-
sumption being that by so doing, the entire system is pro-
tected. The  other approach is to protect the aquatic com-

110/Section III—Freshwater Aquatic Life and Wildlife
munity, the assumption being that the significant species
are not protected unless the entire system is maintained.

Community Structure
  Because  chemical and  physical  environments are con-
tinually  changing—sometimes  gradually  and  sometimes
catastrophically—many species  are necessary to keep  the
aquatic ecosystems functioning  by  filling habitats vacated
because of the disappearance of other species.  Likewise,
when one kind of organism  becomes extremely  abundant
because  of the disappearance  of  one or more  species,
predator species  must  be  available to feed on  the  over-
abundant species and keep it from destroying the function-
ing of  the  community. In  a balanced  ecosystem,  large
populations of a  single species rarely maintain themselves
over a  long  time because predators quickly  reduce their
  Therefore,  the diverse characteristics of a  habitat  are
necessary to the  maintenance of a functioning  ecosystem
in the process of evolution. In  the  fossil record  are found
many  species that  were more common at one  time than
they are today and others that have been replaced entirely.
If it were not for diverse gene pools, such  evolutionary
replacement would not have been possible.
  Some aquatic  environments  present unusual extremes
in their chemical  and physical characteristics. They support
highly specialized  species  that  function  as ecosystems in
which energy flows and  materials cycle.  If  these species
are not present and functioning in  this manner,  such areas
may become  aesthetically distasteful, as has  occurred for
example in the alkaline flats  of the West and the acid bogs
of the Northeast,  Midwest, and  East.
  Rare habitats support rare organisms that become extinct
or endangered species if their habitats are impaired
eliminated.  In the aquatic world there are many spec!
of algae, fish, and invertebrates  that are maintained on
in such rare, fragile habitats. Man must understand the
if he is  to  appreciate the process  of evolution and t
trend of ecological change that brings  about drastic altc
ations to fauna and flora.

Protection of Significant Aquatic Species
   An essential objective of freshwater  quality recomme
dations is the protection of fish and other aquatic organist
for sport or commercial  harvesting. This does  not imp
that all  other aquatic species will be  subject to potent;
extinction, or that an  unaltered environment is the goal
be attained in  all cases.  The average  person  is  usua
interested in only a small number of aquatic sp>ecies,  pri
cipally fish; but it remains necessary to preserve, in certa
unique or rare  areas,  a  diversified environment both i
scientific study and for maintaining species variety.
   It is  sometimes difficult to justify protection  of isolat
organisms  not used by man  unless  it  can be  document
that  they  are ultimately essential  to  the  production
desirable biota.  In some instances it may be that a critic
sensitive species, irreplaceable in the food web  of anoth
more important species, is one known only to the biologi
In such instances, protection of the  "less important" sen
tive species could justifiably determine the water quali
   Because no single  recommendation  can protect all ii
portant  sport and commercial  species unless the  me
sensitive is  protected, a number of species must be co
sidered.  The most sensitive species provide a good estima
of the range of sensitivity of all species.

  Waste discharges do not just go into water but  rather
into aquatic ecosystems. The capacity of such a  system to
receive and assimilate waste is determined by the physical,
chemical, and biological interactions within the system.
Thus the response is a function of the  characteristics of
both  the  ecosystem  and  the nature  and quantity  of the
waste. Understanding the unique  characteristics of each
ecosystem will enable wise users to develop means to  obtain
maximum beneficial use with minimal damage to the system.
Each aquatic ecosystem  is sufficiently unique to require
professional ecological advice to define the problems as-
sociated with  waste discharge into a particular ecosystem.
Such a procedure  has not been customary in the  past, and
this  has  led  to some  unfortunate  consequences, but the
practice is becoming increasingly prevalent.
  Aquatic systems receive  from natural and man-made
sources a  variety of organic and inorganic materials. These
materials through  physical, chemical, and biological inter-
action are transported, rendered, converted, respired, in-
corporated, excreted, deposited and thus assimilated  by the
system. However, not all systems can receive and  assimilate
the same quantity  or kinds of waste materials. The capacity
of each system to  transform waste without  damage  to the
system is a function of the complexity of environmental
  Physical factors such as flow  velocity, volume  of  water,
bottom  contour, rate of water exchange, currents,  depth,
light penetration, and temperature,  govern in  part the
ability of a system  to receive and assimilate waste  materials.
This ability is a function of the reaeration capability of the
system, the physical rendering of wastes, and other physical,
chemical, and biological factors. Most flowing systems have
a greater reaeration  capacity  than standing waters. Fur-
thermore, flowing systems are open systems with continual
renewal of water, whereas standing waters are  closed sys-
tems and act as traps for pollutants.
  Temperature plays a vital role in the rate of chemical
reactions and the nature of biological activities in fresh-
water and  in governing the receiving  and assimilative ca-
pacity of a system. Most temperate  lakes are thermally
stratified part  of the year, except when  there are small
differences between surface  and bottom temperatures  in
the spring and fall. As a consequence little exchange occurs
between  layers during  the period  of stratification.  In
organically  enriched lakes  and reservoirs,  depletion  of
soluble oxygen typically occurs in the bottom layer because
there is little or no photosynthesis and little mixing with the
oxygen-rich surface  layer. As  a result, substances  are  re-
leased from the sediments because certain compounds have
a much greater solubility in a reduced state.
  The unique  chemical characteristics of water govern  in
part the kinds and quantities of waste a system may receive.
Some  of the important chemical characteristics are hard-
ness, alkalinity, pH (associated with the buffering capacity),
and nutrients such as carbon, nitrogen,  and phosphorus.
Because  of synergistic or  antagonistic  interaction with re-
ceiving water,  the effects of a  waste on a wide variety  of
receiving systems are hard to predict.

                                            MIXING  ZONES
  When a liquid discharge is made to a receiving system,
a zone of mixing is created. Although recent public, ad-
ministrative, and scientific emphasis has focused on mixing
zones for the dispersion of heated discharges, liquid wastes
of all types arc included in the following considerations.
(For a further discussion of Mixing Zones see Appendix


  A mixing zone is a region in which a discharge of quality
characteristics different from those of the receiving water
is in transit and progressively diluted from the source to the
receiving system.  In this region water quality characteristics
necessary for  the  protection of aquatic life are based on
time-exposure relationships of organisms. The boundary of
a mixing zone is  where the organism response is no longer
time-dependent. At that boundary, receiving system water-
quality characteristics based on  long-term exposure will
protect aquatic life.


  Although water quality characteristics in mixing
zones may differ from those in receiving systems,
to protect uses in both regions it is recommended
that mixing zones be free of substances attributable
to discharges or wastes as follows:

• materials which form objectionable  deposits;
• scum, oil and floating debris;
• substances producing objectionable color, odor,
  taste, or turbidity;
• conditions which produce objectionable growth
  of nuisance plants and animals.


  The mass emission rates of the most critical constituents
and their  relationship to the recommended values of the
material  in  the  receiving water body are normally the
primary factors  determining the system-degradation po-
tential  of an effluent.  Prior to establishment of a mixir
zone the factors described in Waste Capacity of Reccivir
Waters (Section IV, pp. 228-232) and Assimilative Capa<
ity  (This Section, p. Ill) should IDC considered and a d<
cision made on whether the system can assimilate the di
charge without damage to beneficial uses. Necessary dai
bases may include:

    • Discharge considerations—flow regime, volume, di
      sign, location, rate of mixing and  dilution, plurr
      behavior  and mass-emission  rates of constituen
      including  knowledge of their persistence, toxicir
      and  chemical or physical behavior with time.
    • Receiving system considerations—water quality, li
      cal meteorology, flow  regime (including low-flo
      records), magnitude  of water exchange at point <
      discharge, stratification phenomena, waste capacii
      of the receiving system  including  retention tim
      turbulence and speed  of flow as factors affectir
      rate of mixing and passage of entrained or migratir
      organisms, and  morphology of the receiving systei
      as related to plume  behavior, and biological plr
  Mathematical  models based in part on the above coi
siderations  are available for a variety of ecosystems  an
discharges.  (See  Appendix  II-A.) All such  mathematic
models must be  applied with care  to each particular di
charge and the local situation.

  To avoid potential biological damage  or  into
ference with other  uses of the receiving system
is recommended  that  mixing zone characteristi<
be  defined on  a case-by-case basis after determ
nation that  the  assimilative capacity of the «
ceiving system can safely accommodate the dif
charge  taking into consideration  the  physica
chemical, and  biological characteristics of the dis
charge and the receiving system,  the life histoi
and behavior of organisms in the receiving systen
and desired uses of the waters.

                                                                                             Mixing Dories /113

  Organisms in the water body may be divided into two
groups from  the  standpoint of protection within mixing
zones: (1) nonmobile benthic or sessile organisms; (2) weak
and strong swimmers.
  1.   Nonmobile  benthic  or sessile organisms in mixing
zones may experience long or intermittent exposures  ex-
ceeding recommended values  for  receiving systems and
therefore their populations may be damaged or eliminated
in the local region.  Minimum  damage to these organisms
is attained by minimizing  exposure of the bottom area to
concentrations exceeding levels resulting in harm to these
organisms from long-term  exposure. This may be accom-
plished by discharge location and design.
  The mixing zone may represent a living space denied the
subject organisms and this space  may or may not  be of
significance to the biological community of the receiving
system. When planning mixing zones, a decision should be
made in each case whether the nonmobile benthic and
sessile organisms are to be  protected.

  To  protect populations  of  nonmobile benthic
and  sessile organisms in mixing zones it is recom-
mended  that the area  of their habitat exposed to
water quality poorer than recommended receiving
system quality be minimized by discharge location
and   design  or  that  intermittent   time-exposure
history relationships be denned for the organisms'

  2.   Biological considerations to protect planktonic and
swimming organisms are related to the time exposure history
to which critical organisms are subjected as they are carried
or move  through a mixing  zone.  The  integrated time
exposure history must not cause deleterious effects, including
post-exposure effects. In populations of important species,
effects of total time exposure must not be deleterious either
during or after exposure.
  Weak swimmers and drifting organisms may be entrained
into discharge plumes and carried through a mixing zone.
In determining the  time exposure  history and  responses of
the organisms,  the  possibility  of delayed effects, such as
death, disease,  and increased  vulnerability to predation,
should be investigated.
  Strong swimmers are capable of moving out of, staying
out of, or remaining in  a  mixing zone. Water quality
characteristics which protect drifting organisms should also
protect migrating fish moving through mixing zones.  How-
ever,  there are some discharges that attract animals into
discharge  channels and mixing zones where they are vul-
nerable to death  or shock due to short-term changes in
water quality, such as rapid temperature fluctuations. This
vulnerability  should be recognized and  occurrences that
expose it should be guarded against (see Chlorine, page 189).
  Some free-swimming species may avoid mixing zones and
as a consequence the reduced living space  may limit the
  Free-swimming species may be attracted to a  discharge.
Chronic low-level exposure to toxicants may cause death
or affect growth, reproduction  or migratory instincts, or
result in excessive body-burdens of toxicants hazardous for
human consumption.

  To protect  drifting and both weak and  strong
swimming organisms in mixing zones it is recom-
mended that  scientifically valid data be developed
to demonstrate that the  organisms  can survive
without irreversible damage,  the integrated time-
exposure history to be based on maximum  expected
residence time so that deleterious effects on popu-
lations of important  species do  not occur.


  In mixing zones the exposure of organisms to  stress is of
greater intensity but usually  of shorter duration  than in
the receiving waters,  assuming  no attraction by  the dis-
charge. The objective of mixing zone water quality recom-
mendations  is to provide  time exposure histories which
produce negligible or no effects on populations  of critical
species in  the receiving system.  This objective can be met
by: (a) determination of the pattern of exposure in terms
of time and concentration in the mixing zone due either to
activities of the  organisms, discharge schedule, or currents
affecting dispersion;  and (h)  determination that  delayed
effects do not occur.
  Protection would lie achieved  if the time of exposure met
the relationship  T /ET(x) < 1  where T is the time of the
organism's exposure  in  the  mixing zone to a specified
concentration, and ET(x) is the effective time of exposure
to the specified concentration, C, which produces (x)  per cent
response in a sample of the organisms, including  delayed
effects after extended  observation. The per  cent response,
(x). is selected on the  basis of what is considered  negligible
effects on  the  total  population and  is then symbolized
ET(25), ET(5),  ET(O.l), etc.
  Because concentrations vary within mixing zones, a more
suitable quantitative statement than the simple relationship
 114:/Section III—Freshwater Aquatic Life and Wildlife
tration Ci during the time interval TI, to concentration Cs
during the time interval T2, etc. The sum of the individual
ratios must then not  exceed unity.  (See  caveat  below,
Short Time Exposure Safety Factors.)
  Techniques  for securing the above information,  appli-
cation to a hypothetical field situation, comments, caveats,
and limitations are expressed  in Appendix II-A, Mixing
Zones, Development of Integrated  Time Exposure  Data,
p. 403. Tabular data and formulae for summation of short-
term effects of heated discharges on aquatic life are provided
in the Heat'and Temperature discussion, page  151.


  This concept  of  summation of short-term  effects  and
extrapolation is an  approach which tests the applicability
of present  bioassay methodology  and precision and may
not be universally  applicable to  all types of discharges.
Conservatism in application  should be practiced.  When
developing the summation of short-term  thermal  effects
data,  a safety factor of two degrees centigrade is incorpo-
rated. In development of summation of short-term toxicity
effects data, a safety factor exists if a conservative physio-
logical or behavioral response is used with effective time of
exposure. However, when mortality is the response plotted,
an application factor must be incorporated to provide an
adequate margin of safety. This factor can most easily be
applied by lowering the sum of the additive effects to some
fraction of 1  so that the  sum of Ti/(ET(x)  at  Ci) • • • +
Tn/(ET(x) at Cn) then equals 0.9, or less. The value must
be based on scientific knowledge of the organism's behavior
and response to the contaminants involved.

  When developing  summation of short-term  ex-
posure  effects it  is  recommended  that safety
factors, application factors, or conservative physio-
logical or behavioral  responses be  incorporated
into  the  bioassay or extrapolation procedures to
provide an adequate margin of safety.


  If mixing zones are  contiguous or overlap, the formula
expressing  the integrated  time exposure history for single
plumes should  be adjusted. Synergistic effects should be
investigated, and if not found, the assumption may be made
that effects of multiple  plumes are  additive.

  When two plumes are contiguous or overlap and
synergistic  effects  do  not occur, protection  for
aquatic life should  be provided if  the sum of  the
fractions of integrated  time  exposure effects  for
each plume total <0.5. Alternatively, protection
should be provided  if the  sum of the fractions for
both plumes  (or  more  than two  contiguous  o
overlapping plumes) is < 1. (See caveat above, Shot
Time Exposure Safety  Factors.)


  In the event  information on summation effects of th
integrated time  exposure  history cannot be satisfactoril
provided, a conservative single figure concentration can 1:
used for all  parts of the mixing zone until  more detaile
determinations of the time-exposure relationships are d(
veloped. This single, time-dependent median lethal concer
tration should be subject to the caveats found throughoi
this Section  and Appendix [I-A regarding delayed effec
and behavioral modifications.  Because  of the variables ir
volved,  the  single  value must be applied  in the light  (
local conditions. For one situation a 24-hour LC50  migt
be adequate to protect aquatic life.  In  another situation
96-hour LG50 might provide inadequate protection.


  The  time-dependent three dimensional shape of  a di:
charge plume  varies with  a multitude  of receiving syster
physical factors  and  the discharge design. While time e>
posure water quality characteristics within mixing zom
are designed to  protect aquatic life, thoughtful placemer
of the discharge and planned control  of plume behavk
may increase the level of ecosystem protection, e g., floatin
the plume on the  surface  to protect the deep water of
channel; discharging in midstream or  offshore to prote<
biologically-important littoral areas;  piping the efflueT
across a river to discharge on the far side because fis
historically migrate on the  near  side;  or piping the cli
charge away from a stream mouth which  is used by m
grating  species.  Such engineering modifications can som<
times accomplish  what is  necessary  to  meet  biologic;
  Onshore discharges generally have  more potential  fc
interference  with other uses than offshore discharges. Fc
example the plume is more liable to impinge on the bottot
in shallow areas of biological productivity and be closer t
swimming and recreation areas.


  Recommendations for mixing zones do not protect again
the long-term  biological  effects  of sublethal condition
Thus water quality  requirements necessary to protect a
life stages and  necessary  functions of aquatic  organisn
such as  spawning and larval development, are not provide
in mixing zones, and it is  essential to insure that adequal
portions of every water body are free of mixing zones. Tli
decision as to  what portion and areas must be retained i
receiving water quality values  is both a social and scientiii

                                                                                            Mixing ^ones/115
decision. In reaching this decision, data input should in-
clude current and  projected information on  types and
locations of intakes and discharges; percentage of shoreline
necessary to provide  adequate  spawning,  nursery, and
feeding areas; and other desired uses of the water.

  It is recommended that the total area or volume
of a receiving system assigned to mixing zones be
limited  to that which  will: (1)  not interfere with
biological communities or populations of impor-
tant species to a degree which is damaging to the
ecosystem; (2) not diminish other beneficial uses


  In river systems, reservoirs, lakes,  estuaries, and  coastal
waters, zones of passage are continuous  water routes of
such volume, area, and quality as to allow passage of free-
swimming and  drifting  organisms so  that no significant
effects are produced on  their populations.
  Transport of a variety of organisms in river water and
by tidal  movements in  estuaries  is biologically important
in a number of  ways;  e.g.,  food is  carried to the  sessile
filter feeders and  other nonmobile organisms; spatial distri-
bution of organisms and reinforcement  of  depauperate
populations is enhanced; embryos and larvae of some fish
species develop  while  drifting.  Anadromous  and cata-
dromous species must be able to reach suitable spawning
areas. Their young (and in some  cases the adults) must be
assured a return route  to  their growing and  living areas.
Many species make migrations  for  spawning  and other
purposes. Barriers or blocks which prevent or interfere with
these types of essential  transport and movement can  be
created by water of inadequate chemical or physical quality.
  Water quality in the zone of passage should be such that
biological responses to the water quality characteristics of
the mixing zone are no longer time-dependent (see Defini-
tion of Mixing Zone on page 112). However, where a zone of
passage is  to  be  provided,  bioassays determining time-
exposure responses in the mixing zone should include addi-
tional requirements to assess organism behavior.  In  the
mixing zone discussion above it is assumed that entrainment
in the plume will be involuntary.  However, if there is at-
traction due to plume composition, exposure in the plume
could be very much longer  than  would be predicted by
physical modeling. If avoidance  reactions occur, migration
may be thwarted.  Thus, concentrations in both the mixing
zone and the zone of passage  should be reduced before dis-
charge to levels below those at  which such  behavioral
modifications affect the populations of the subject organisms.
  Modern  techniques of waste water  injection  such  as
diffusers  and  high  velocity jets  may form barriers to free
passage due to responses of organisms to currents.  Turbu-
lence of flows opposing stream direction may create traps
for those  organisms which migrate upstream by orientation
to opposing currents. These organisms may remain in the
mixing zone in response to currents created by the discharge.


  Because of  varying local physical and  chemical
conditions and  biological phenomena, no single-
value  recommendation can be  made on the per-
centage of river width necessary to allow passage of
critical  free-swimming and  drifting organisms so
that negligible or no effects are produced on their
populations. As  a guideline no more than  % the
width of a water-body should be devoted to mixing
zones  thus  leaving at  least yA free  as a zone of

                                       BIOLOGICAL  MONITORING
  Monitoring of aquatic environments has traditionally in-
cluded obtaining physical and chemical data that are used
to evaluate the effects  of pollutants on living  organisms.
Biological  monitoring  has  received  less  emphasis  than
chemical or physical monitoring, because biological assess-
ments  were once not as readily  amenable  to  numerical
expression  and tended  to be more  time  consuming  and
more expensive. This is no longer true. Aquatic organisms
can serve as natural monitors of environmental quality and
should be included in programs designed  to provide con-
tinuous records of water quality,  because they integrate
all of the stresses placed on an  aquatic system and reflect
the combined effect. Chemical-physical assessments identify
individual components,  so the two  types of assessments are
mutually supporting rather than mutually  exclusive.
  A  biological  monitoring  program is  essential in  de-
termining  the  synergistic or antagonistic interactions  of
components of waste discharges  and the resulting effects on
living organisms. However,  biological monitoring does not
replace chemical and physical monitoring; each  program
provides information supplemental  to the others.


  An ideal  biological monitoring program has four com-
ponents' (1) field surveys, (2) in-plant biological monitoring,
(3) bioassays, and (4) simulation techniques. Obviously no
biological monitoring program is routine, nor does it neces-
sarily have to include all of the above components. However,
each  of the  components provides  valuable  and useful


  Field surveys  are needed to obtain adequate data on
biological,  chemical, and physical water quality  to  de-
termine the nature of the system and the  possible adverse
effects of waste discharges on beneficial uses of the system.
Two methods  for continuously monitoring  the effects of
pollution on a receiving water have been described. Patrick
et al. (1954)6* described the use of diatoms as natural moni-
tors of various types of pollution. Various species of shellfish,
especially oysters suspended in trays, have  been describee
as an effective method of monitoring pollution  (Galtsof
et al. 1947).4 Field surveys should be carried out at suitabli
intervals depending on local  conditions. For example, it
determining  the impact of a  new  or relocated municipa
or industrial discharge,  it is desirable to  perform  tin
following functions:

    • survey the stream as a  part of the site selection pro
    • continue the field survey prior  to  construction t(
      determine existing water quality: at this time it i
      also useful to make bioassays using simulated plan
      wastes and  representative  organisms from the  re
      ceiving  systems,  and  to  establish biornonitorins
    • monitor the effects of construction;
    • carry  out bioassays using actual plant wastes anc
      effluents after the  plan! is in  operation, and mak<
      field surveys to determine any changes from pre
      construction results.

  Body burdens of toxicants  that can be concentrated  bi
biota should  be measured regularly. These data can provide
early warning before concentrations in water become readil;
available and can provide warnings  of  incipient  effects u
the biota being monitored.


  Present information systems do not provide data rapidh
enough to be of use in  environmental  management, because
the constituents of a waste stream are likely to vary frort
hour  to hour  and from  day  to day. Potentially harmfu
materials should be detected before they enter the receivin;
water and before substantial damage has been done to  tht
  * Citations are listed at the end of the Section. They can be locatec
 alphabetically within subtopics or by their superior numbers whict
 run consecutively across subtopics for the entire Section.

                                                                                           Biological Monitoring/117
  Several potentially  useful  methods  for  rapid in-plant
monitoring are being explored (Sparks et al. 1969,7 Waller
and Cairns 19698), and one rapid in-stream method is now
operational (Cairns et al. 1968,2 Cairns and Dickson 19713).
These  in-plant methods use changes in heart rate, respi-
ration, and movements of fish within a container to detect
sublethal concentrations of toxicants in a waste discharge.
Continual information on toxicity of a waste should enable
sanitary engineers to identify those periods likely to produce
the most toxic wastes and  to identify those components of
the production  process that  contribute  significantly  to
toxicity.  This  could be accomplished with bioassays  as
they are currently used, but  rarely are enough samples
taken over a period  of time sufficient  to give the range of
information that  would be  available with continually oper-
ating bioassay techniques.


  Of equal importance to the river surveys and the in-plant
and  in-stream monitoring systems is  the availability  of
toxicity information based on a predictive  bioassay. The
bioassay provides valuable information pertaining to the
effects  of potential or  contemplated discharges on aquatic
life. Acute bioassays are useful as a shortcut or predictive
method of estimating safe concentrations by use of suitable
application  factors for many pollutants,  as recommended
throughout this Report.
  However, determining only the  acute lethal toxicity of
wastes is no longer adequate. Good health and an ability
to function vigorously  are  as important for aquatic eco-
systems as they are for humans. The  former end point of
bioassays, viz., death, has been supplanted by more subtle
end  points such as the protection of respiration,  growth,
reproductive success,  and  a variety  of other functional
changes  (Cairns 1967).* Acute toxicity determinations are
being supplemented by long-term tests often involving an
entire life cycle. The latter require more time and expense
than short-term tests,  but they  provide  better predictive
information about biologically safe concentrations of various
toxicants. Bioassays of organisms other than fish are be-
coming  increasingly common because of the  realization
that elimination of the lower organisms can also have serious


  The fourth component now available to provide ecological
information is the use  of scale models. Models are used to
study major ecological or environmental problems by simu-
lating  prospective new uses. Engineering scale models are
common,  but  ecological scale  models or  environmental
simulation systems are not yet as commonly used. Experi-
mental streams and reservoirs  have  been constructed  to
predict toxicity of waste discharges,  determine factors re-
sponsible for productivity  of aquatic communities, and
answer questions about plant site location (Haydu 1968,6
Warren  and Davis 19719).

  Bioassays are used to evaluate a given pollutant in terms
of existing water quality. Most pollution problems involve
discharges of unknown and variable composition where
more than one toxicant or stress is present. In evaluating
criteria for specific toxicants, consideration must be given
to other environmental influences such as dissolved oxygen,
temperature, and pH.
  Harmful effects of pollutants can be described by one or
more of the following terms:

     acute—involves a stimulus severe  enough to bring
         about a response speedily, usually within four days
         for fish.
     subacute—involves a stimulus less  severe than  an
         acute stimulus, producing a response in a longer
         time; may become chronic.
     chronic—involves a  lingering or continuous stimu-
         lus ; often  signifying periods of about one-tenth of
         the  life span or more.
     lethal—causes death  by direct action.
     sublethal—insufficient to cause death.
     cumulative—brought about, or increased in strength,
         by successive additions.

  Two broad categories of effect (Alderdice  1967)10 may
be distinguished: acute toxicity which is usually lethal, and
chronic toxicity which may be lethal or sublethal.

  Most of the available toxicity data are reported as the
median tolerance limit (TLm  or  TL50)  or median lethal
concentration (LC50). Either symbol signifies the concen-
tration that kills 50 per cent of the test organisms within a
specified time span, usually in 96 hours. The  customary
96-hour (four-day) time period is recommended as adequate
for most routine tests of acute toxicity with fish. A threshold
of acute toxicity will have been attained within this time
in the majority of cases (Sprague 1969).43 This lethal threshold
concentration  is usually noticeable  in  the  data.  Sometimes
mortality continues, and tests of a week or longer would  be
necessary to  determine the threshold. The lethal threshold
concentration should be  reported if it is demonstrated
because it is better  for  comparative  purposes  than  th
arbitrary 96-hour LG50. Absence of any apparent threshol<
is equally noteworthy.
  The median lethal concentration is a convenient referenc
point for  expressing  the  acute lethal toxicity of a  givei
toxicant to the average or typical test animal. Obviously  i
is in no way a safe  concentration,  although occasional!
the two have  been  confused.  Safe  levels, which permi
reproduction, growth, and  all other normal  life-processe
in the fish's natural habitat, usually  are much lower thai
the LC50.  In this  book, the recommended  criteria  ar
intended to be safe levels.
  Substantial data on long-term effects and safe levels ar
available  for only a  few  toxicants. Information is now ac
cumulating on the effect  of toxicants on reproduction, a
important aspect of all long-term toxicity tests. Other infot
mation  is being  gathered on sublethal effects on growth
performance, avoidance reactions, and social  behavior c
fish. Also  important is the sensitivity of organisms at variou
life stages. Many organisms are most  sensitive  in the larva
nymphal, molting, or fry stage; some are most sensitive i
the egg and sperm stage.
  It would be desirable  if  a single,  universal, rapid, bic
logical  test could be used  to measure directly sublethx
effects of a pollutant. Data on sublethal responses of fis
have been used, such as respiratory rates and "coughing,
swimming speed, avoidance behavior, and specific physic
logical and biochemical changes in various organisms; an
histological studies  have  been made. A  review of thes
(Sprague 1971)45 shows that no single test is meaningful fc
all  kinds  of pollutants.  Therefore, it is recommended th;=
routine assessment and prediction of safe levels be made b
carrying out bioassays for  acute lethal toxicity and multiply
ing the lethal concentration  by a suitable application factoi
The application factors used and recommended here hav
been derived principally  from chronic or sublethal labors
tory experiments or from well documented field studies c
polluted situations.
  Acceptable concentrations of toxicants to which organism
are exposed continually  musl  be lower than the  highe

concentrations that may be reached occasionally but briefly
without causing damage. Both maximum short-time con-
centrations and the more restrictive range of safe  concen-
trations for continuous exposure are useful. The recommen-
dations in this Report are  those  considered safe for con-
tinuous exposure,  although  in  some cases  there has also
been  an indication of permissible higher levels for short
  In  field situations  and industrial  operations,  average
24-hour concentrations can  be determined by  obtaining
composite  or continuous  samples.  After  24 hours,  the
sample  may  be mixed and  analyzed.  The  concentration
found  will represent the  average concentration. Samples
obtained  this way are more reproducible and easier  to
secure than the instantaneous sample of maximum  concen-
trations. However,  average concentrations are of little sig-
nificance if fish are  killed by a sharp peak of concentration,
and  for that  reason maximum concentrations  must also
be considered.

  Although there are many types  of assays, two  are  in
general use:

  1.  the static bioassay in which the organisms are held
in a tank containing the test solution, and
  2.  the  continuous  flow  or  flow-through  bioassay  in
which the test solution is renewed continually.

The difference between the two  types is not always great,
but one can have clear advantages over the other.
  An outline  of methods  for routine  bioassays has  been
given in "Standard Methods for the Examination of Water
and Wastewater" (American Public Health  Association,
American Water Works Association, Water Pollution Con-
trol Federation,  1971,11 hereafter referred to as Standard
Methods 197148). Cope  (1961)21  described  bioassay re-
porting, and  Cairns  (1969)20  presented  a rating  system
for  evaluating the quality of the tests.  Sprague  (1969,43
1970,44  197145) reviewed research to develop more incisive
testing methods. Their findings are utilized in this Report.
  Procedure for acute bioassay with fish is now relatively
standardized and usually incorporates:

     • a series of replicate  test containers,  each  with  a
       different but constant concentration of the toxicant;
     • a group of similar fish, usually 10, in each container;
     • observations of fish mortality during exposures that
       last between  one day and one week, usually four
       days; and
     • final results expressed as LC50.

  Other factors that are required for good bioassay practice
are briefly summarized in  the references mentioned above.

  A selected strain  of fish  or  other  aquatic  organisms of
local  importance should  be used in  bioassays conducted
for  the  purpose of  pollution  monitoring.  Preferably it
should be a game or pan fish, which are usually among the
more sensitive. Ability to duplicate experiments is enhanced
by  the use of a selected strain of test organisms (Lennon
1967).31  A selected  strain can also help  to determine the
difference between toxicants more reliably,  and to detect
discrepancies in results  due to apparatus. A National Re-
search Council subcommittee chaired by Dr. S. F. Snieszko
is currently preparing a report, Standards and guidelines for
the  breeding,  care, and management of laboratory animals—Fish,
which will be  useful in this area. Susceptibility to toxicants
among different species of fish is generally less than might
be  expected—sometimes  no greater than when a single
species is tested in different types of water. For example,
trout and  certain coarse fishes were equally resistant to
ammonia when  tests continued for several days to give the
less sensitive species  time to react (Ball 1967a);13 and even
for  zinc, the coarse fishes were no more  than 3.8 times as
resistant as trout (Ball 1967b).14 Recommendations for the
selected  test fish  will often provide  protection  to  other
aquatic animals and plants. There  are exceptions to this
generalization: for example, copper  is quite  damaging to
algae and mollusks, and insecticides are especially dangerous
to aquatic arthropods. Sufficient data exist to predict these
situations.  When they  are  expected,  bioassays should  be
run with two kinds of invertebrates and two kinds of algae
(Patrick et al. 1968).41
  In  the case of important bodies of water, there is good
reason to test several kinds of aquatic organisms in addition
to fish. Patrick et al. (1968)41 made a comparative study of
the effects of 20 pollutants on fish, snails, and diatoms and
found that  no single kind of organism was  most sensitive
in all situations. The short-term bioassay method for fish
may also be used for many of the larger invertebrate ani-
mals. A greater volume of  test water and rate  of flow,  or
both, may be  required in relation to weight of the animals
since their metabolic rate is higher on a weight basis.
  Larvae of mollusks or crustaceans can  be  good test ani-
mals. The crustacean Daphnia is a good test animal and was
widely used in comparative studies of toxicants by Ander-
son (1950).12  Recently  Biesinger and Christensen (unpub-
lished data,  1971)52 have carried out tests on  the chronic
effects of toxicants on growth,  survival, and  reproduction
of Daphnia magna. Because of the rapid life cycle  of Daphnia,
experiments on chronic toxicity can be completed in about
the same time as an acute toxicity test with fish.
  Patrick et al. (1968)41  have shown that diatoms, snails
and fish exposed for roughly comparable periods of  time
and in similar environmental conditions very  often have
similar  LC50's, but at other times these may differ greatly.

 120/Section III—Freshwater Aquatic Life and Wildlife
However, for some  toxicants diatoms were most sensitive;
for others, fish; and for others, snails. When one is comparing
data of this type, one questions whether a LC50 for a diatom
population in which a number of divisions have occurred
during the test  period  is comparable to  that obtained  for
fish and snails in which no reproduction has occurred during
the test period. In the sense that there are 50 per cent fewer
cells in the LC50 concentration than there are in the diatom
control culture, the test is somewhat equivalent to a test
of acute  toxicity that results in 50 per cent fewer surviving
fish in the LC50 than in the control  container. Also loss of
ability to grow and divide  might be just as fatal to a micro-
bial population as  death  of a substantial number of its
members would be to a fish population.
  When the  absolute time for the test is considered, there
are also reasons for believing  that exposure of diatoms to a
toxicant  through several generations might  not constitute
a chronic test, because it is quite possible that for toxicants
to accumulate in a  cell may require a period of exposure
much more lengthy  than that encompassed in the average
test which only spans  a few generations. This would  be
particularly true when the organisms were dividing rapidly
and the  additional protoplasm  diluted the material being

Dilution  Water
  Toxicants should be tested  in the water that will receive
the pollutant in question. In this way all modifying factors
and combined toxicities will be present.  It is  not advisable
to use tap water  for dilution, because it may contain chlorine
and other harmful materials  such as copper,  zinc, or lead
from  plumbing  systems. Routine dechlorination does not
insure complete removal of chlorine.
  Variations  in physical  and chemical  characteristics of
water affect  toxicity of pollutants. Effects of five environ-
mental entities  on the  lethal threshold  of ammonia were
illustrated a decade ago (Lloyd 1961b).34 Hardness of water
is particularly important in  toxicity of metals.  Hydrogen
ion concentration is an important  modifying  factor  for
ammonia and  cyanide.  Higher  temperatures  sometimes
increase  toxicity of a pollutant, but recent work shows that
phenol,  hydrogen cyanide, ammonia, and   zinc  may  be
more toxic at low temperatures (United Kingdom Ministry
of Technology  1969).50 Dissolved oxygen levels that are
below saturation will increase toxicity, and this is predictable
(Lloyd 1961a;33 Brown 1968).16
  The supply of dilution water must be adequate to main-
tain constant test conditions. In both static and continuous
flow tests, a sufficiently large  volume of test water must be
used, and it  must be replaced or replenished frequently.
This is to provide oxygen for the organism and dilution of
metabolic wastes, to limit changes in temperature and pH,
and to compensate for degradation, volatilization,  intake,
and sorption  of  the toxicant. In static tests, there should be
two or three  liters of water per gram  of fish, changed daily,
or increased proportionally in volume for the number  of
days of the test. In continuous  flow tests,  the  flow  must
provide at least two or three liters of water per gram of fish
per day,  and it  must equal  test-volume  in  five hours  or
less, giving 90 per cent replacement in half a day or less.


  Acclimatizing  the  test organism  to  the  specific water
before the bioassay begins  may  have marked effect  upon
(he outcome. Abrupt changes  in quality of the water should
be avoided. Time for  acclimation of the organisms to the
conditions of the diluent water  should  be as generous  as
possible, dependent on  life span. At  least  two weeks  is
recommended for fish.

Test Methods

  Test  methods  must be adequately described when the
results are given. Several bioassay procedures are listed  in
Table III-l. Adequate and appropriate control tests must
always  be run (Sprague 1969).43 Survival  of the  control
organisms is a minimum indication of the  quality of the
test organisms. In addition, levels of survival and health
in holding tanks should be indicated and the conclusions
TABLE III-l—Recommended Literature Sources for Bioassay
    and Biomonitoring Procedures with Various Aquatic
   Kind of organism
Type of response    Appropriate situations for use
Fish and Macroinverte-

Fish and macromverte-
Fish and inverte-


Fisb (i.e., fathead min-
nows, brook tiout.



Marine crustacean,
larvae mollusks

96-hour lethal concen-

Lethal threshold con-
Incipient lethal tem-
peratures & ultimate
incipient lethal tem-
Respiratory movements
as acute sublethal
Reproduction, growth,
and survival

Survival, growth, and

Survival, growth, and

Survival, growth, and
development through
immature states
To measure lethal toxicity ef a
wiste of known or unknown
composition. To serve as a
foundation for extrapolating
to presumably salt cimcentta-
tinns. To monitor industrial
For research applications to
document lethal thresholds.
For research to determine
lethal temperature ranges ol
a given species.

Quick (1-day) indication of
possible sublethal effects.
Fur research and monitoring.
Chronic tests for research on
safe concentrations.

Rapid completion of chronic
tests for testing special sus-
ceptibility of crustaceans
A sensitive, rapid, chronic test
for research, prediction, or
A sensitive, rapid, chronic test
for research, prediction, or
Standard Methods 1971"

Sprague 1969," 1970"

Fry 1947," Brett 1952"

Schaumburg et al. 1967"

Mount 1968," Mount i
Stephan 1967,"
Brungs 1969," McKim
I Benoit 1971," Eaton
Anderson 1950,1= Bit-
sinter & Christensen
(Unpublished data)"
Patrick 1968"

Woelke 1967"

 »requires an operator with some specialized Biological training.

                                                                                                     Bioassay s/121
Dissolved Oxygen
   The problem of maintaining dissolved oxygen  concen-
trations suitable for aquatic life in the test water can  be
difficult. The suggestions on test volume and replacement
times (see Dilution Water above) should provide for ade-
quate oxygen in most rjases. However, with some pollutants,
insufficient oxygen may be present in the test water because
a biochemical and a chemical oxygen demand  (BOD and
COD) may consume much of the available dissolved oxygen.
Aeration or oxygenation may degrade or remove the test
material.  Devices  for  maintaining satisfactory dissolved
oxygen in static tests have been proposed and used with some
degree of effectiveness,  and  are  described  in  Doudoroff
et al. (1951).22

  Periodic measurements of concentration of the toxicant
should be made at least at the beginning and  end of the
bioassay. If this is not possible, introduced concentrations
may be stated alone, but it should be realized that actual
concentrations in the water may become reduced.
  In the flow-through type of bioassay, a large quantity of
test water can be made up and used gradually. More often
a device is used to add toxicant to a flow of water, and the
mixture is discharged into the test container, using apparatus
such as "dipping  bird" dosers described by Brungs and
Mount (1967).19  Other  devices have been  developed  by
Stark  (1967),47 and Mount  and  Warner (1965),39  using
the doser technique.
Evaluation of Results
  Mortality rates  at the  longest exposure time should  be
plotted on a vertical probit scale against concentrations of
toxicants on a horizontal logarithmic  scale. The concen-
tration which causes 50 per cent mortality can be read and
used as LC50. Errors in LC50 can be estimated using the
simple nomograph  procedures described by Litchfield and
Wilcoxon (1949).32 A more refined estimate of error may
be made using the  methods of Finney (1952),25 which can
be programmed for a computer.
  The value of the results would be improved if the LCSO's
were  estimated  (by  the above  procedures) at  frequent
exposure times such as  1, 2,  4, 8±1,  14±2,  24, 48,  72,
and 96 hours. A toxicity curve of time versus LC50  could
then be constructed on logarithmic axes. The lethal thresh-
old concentration  could then be estimated in  many cases
(Sprague  1969)43 to provide  a more valid single number
for description of acute toxicity than the arbitrary 96-hour
  For  some purposes,  such as basic research or situations
where  short exposures are of  particular concern,  it would
be desirable to follow and plot separately the mortality of
the group of fish in each tank. In this way, the  median
lethal  time  can be estimated for  a given concentration.
Methods for doing  this are given in Appendix II-A.

  Short-term or acute toxicity tests do not indicate concen-
trations of a potential toxicant that are harmless under
conditions of long-term exposure. Nevertheless,  for  each
toxicant there is obviously a numerical value for the  ratio
of the safe concentration to the acutely lethal concentration.
Such values  are called application factors. In  some  cases
this  safe-to-lethal ratio is  known with reasonable  accuracy
from experimental work, as in the examples given in Table
III-2. However,  for most toxicants,  the safe level has not
been determined, and must be predicted by some approxi-
mate method.  In  these  cases,  the assumption has  been
made in this Report, that the numerical value of the  safe-
to-lethal ratio, the application factor,  is constant for related
groups  of chemicals. Values for the  ratio will  be recom-
mended. The safe level of a particular  toxicant can  then
be estimated approximately by  carrying out an acute bio-
assay to determine  the lethal concentration, then multi-
plying this by the suggested application factor. An appli-
cation factor does not make allowance for unknown factors.
It is merely a fractional or decimal factor applied  to  a
lethal  concentration  to estimate the safe concentration.
  Ideally, an application factor should be determined for
each waste material in question. To do this, it is necessary
first  to  determine  the lethal concentration of the waste
according to the bioassay procedures outlined  above. To
obtain the application factor,  the safe concentration of the
same waste  must  be determined for  the  same  species by
thorough  research on physiological,  biochemical, and be-
havioral effects,  and  by  studying growth,  reproduction,
and  production in the laboratory  and field.  The safe-to-
lethal ratio obtained could  then be used as an application
factor in a given  situation,  by working from the measured
LC50 of  a  particular  kind of  waste to  predict  the  safe
TABLE III-2—Ratios between the safe concentration and the
lethal  concentration which have been  determined experi-
mentally for potential aquatic pollutants. Sources of data
are given in the sections on the individual pollutants.
                        Species of animal
                                             Safe-to-lethal ratio



Trivalent chromium
Hexavalent chromium

Zinc .
Fathead minnow (Pimephales promelas)

Fathead minnow
Fathead minnow and white sucker (Catostomus commersoni)
Walleye pike (Stizostedion vitreum v.)
Several species of fish
Fathead minnow
Fathead minnow
Brook trout (Salvennus fontinalis)
Rainbow trout (Salmo gairdnen)
Fathead minnow and bluepll (Lepomis machrochirus)
Fish species
Fathead minnow
Rainbow and Brook trout
Fathead minnow
Between 0.14 and 0.28
0 22±
close to 0.1

 122/'Section III—Freshwater Aquatic Life and Wildlife
  In this approach, a 96-hour LC50 is determined for the
pollutant using water from the receiving stream for dilution.
The test organisms selected  should be among the most
sensitive species, or an important local species at a sensitive
life  stage, or a species whose  relative sensitivity is known.
This procedure takes into consideration the effects of local
water quality and the stress  or adverse  effects of wastes
already present in the stream. The LC50  thus  found is
then multiplied by the application factor for that waste to
determine  its safe concentration in the specific stream or
section  of  stream.  Such bioassays should be  repeated at
least monthly or when changes in process or rate of waste
discharge are observed.
  For example, if the 96-hour LC50 is 0.5 milligrams per
liter (mg/1) and the concentration of the waste found to be
safe is 0.01  mg/1. the ratio would be:
              Safe Concentration   0.01    1
                96-hour LC50   ~~ 0.50 ~ 50
In this  instance, the  safe-to-lethal ratio is 0.02. It can be
used as an application factor  in other situations.  Then, in
a given  situation involving this waste, the safe concentration
in the receiving stream would be found by multiplying the
four-day LC50 by 0.02.
  This predictive procedure based on lethal concentrations
is useful, because the precise safe  level of many pollutants
is not known because of the uncertainty  about toxicity of
mixed effluents and the difference in sensitivity among fish
and fish food organisms. Henderson (1957)27 and  Tarzwell
(1962)49 have  discussed  various  factors  involved  in  de-
veloping application factors. Studies by Mount and Stephan
(1967),;!S Brungs (1969),18 Mount (1968),37 McKim  and
Benoit  (1971),3C and Eaton (1970)21 in  which continuous
exposure was used, reveal that  the safe-to-lethal ratio that
permits spawning  ranges over nearly two orders of magni-
tude.  Exposure will  not  be constant in most cases,  and
higher  concentrations usually can  be  tolerated  for short
  Lethal threshold concentrations, which may require more
than 96-hour exposures, may be beneficially used  (Sprague
1969)43 to  replace 96-hour LC50 in the above procedures,
and there  is a trend today to use such threshold concen-
trations (Eaton 1970).24
  At present, safe levels have  been detennined for only a
few wastes, and as a result only a few application factors are
known. Because the determination of safe levels of pollutants
is an  involved process, interim procedures for estimating
tolerable concentrations of various wastes in receiving waters
must be used. To meet this situation, three universal appli-
cation  factors selected on the  basis of present knowledge,
experience, and judgment are recommended at the end of
this section.  Where toxicants  have a nonpersistent nature
(a half life of less  than 4 days) or noncumulative  effects,
an  application factor of 0.1 of the 96-hour LC50 should
not be exceeded at any time or place after mixing with the
receiving waters. The 24-hour average of the concentratioi
of these toxicants should not exceed  0.05  of the LC50 i
aquatic life is to be protected.  For toxic materials whicl
are persistent or cumulative the concentrations should no
exceed 0.05 of the 96-hour LC50 at any time or place, am
the 24-hour average concentration should not exceed 0.0
of the 96-hour  LC50 in order to protect aquatic life. It i
proposed that these general application factors be appliec
to LC50 values determined in the manner described abov<
to set tolerable concentrations  of wastes in the receivini


  The toxicity  of a mixture of pollutants may be estimate!
by expressing the  actual concentration of each toxicant a
a proportion of its lethal threshold  concentration  (usual!1
equal to  the 96-hour  LC50)  and adding  the  resultin;
numbers for all the toxicants. If the total is 1.0 or greater
the mixture will be lethal.
  The system of adding  different toxicants in  this way i
based on the premise that their lethal actions are additive
Unlikely as  it  seems,  this simple rule has been  found ti
govern the combined lethal action of many pairs and mix
tures of quite   dissimilar  toxicants,  such  as  copper  am
ammonia, and  zinc and  phenol in the laboratory (Hcrber
and  Vandyke   1964,2<)  Jordan  and Lloyd 1964,30 Browi
et al. 1969).17 The rule holds true in field  studies (Herber
1965,2S  Sprague et al. 1965).4(l The method of addition i
useful and reasonably accurate for predicting thresholds c
lethal effects in  mixtures.
  There is also evidence of a lower limit for additive letha
effects.  For ammonia and certain other pollutants, level
below 0.1 of the lethal concentration do not seem to con
tribute to the lethal action of a mixture (Brown el al. 1969,1
Lloyd  and  Orr 1969).35 This lower cutoff point of 0.1 c
the LC50 should be used when it is necessary to assess th
lethal effects of a mixture of toxicants.


  Sublethal  or chronic effects of mixtures  are of great  im
portance.  Sublethal  concentrations of different  toxicanl
should  be  additive in effect. Here again,  it would be  e:<
pected that for any given toxicant there would be some lov
concentration that would have  no deleterious effect on ai
organism  and would not contribute any sublethal toxicit
to a mixture,  but there  is little research  on  this subject
Biesinger  and  Christensen {unpublished data  1971),62 con
eluded  that subchronic concentrations of 21 toxicants wer
close to being additive in causing chronic effects on repro
duction in  Daphnia. Copper and zinc concentrations c
about 0.01  of the LC50 are additive in causing avoiclanc
reactions (Sprague et al. 196.3).46 On the other hand, some
what lower metal concentrations of about 0.003 of the LC5I
do not seem to be additive in affecting reproduction of fisl

 (Eaton unpublished data 1971).63 Perhaps there is  a lower
 cutoff point than 0.01 of the LC50  for single  pollutants
 contributing to sublethal  toxicity of a mixture.
   As an interim solution, it is recommended that the con-
 tribution of a single pollutant to the sublethal toxicity of a
 mixture should not be counted if it is less  than  0.2 of the
 recommended  level for that pollutant. Applying this to a
 basic recommended level of 0.05 (see the Recommendation
 that follows) of the LG50 would yield a value of 0.01 of the
 LC50, corresponding to the possible cutoff  point suggested
   It is expected that certain cases of joint toxicity will not
 be covered by simple addition. The most obvious exception
 would  be when  two  toxicants  combine chemically. For
 example, mixed  solutions of cyanides and  metals could
 cause addition of toxicity or very different effects if the
 metal and cyanide combined (Doudoroff et al. 1966).23 A
 thorough understanding of chemical reactions is necessary
 in these cases.
   For further discussions of bioassays  and  the difficulties
 posed in assessing sublethal effects of toxicants on organisms,
 see Section IV, pp. 233-237.

 Recommendations for the Use of Application Factors to
 Estimate Safe Concentrations of Toxic  Wastes in Receiving

   Where specific application factors have been determined
for a given material, they should be used instead of the safe
concentration levels of wastes given below:
   (a)   Concentration of materials that are nonpersistent
or have noncumulative effects  should not  exceed 0.1  of
 the 96-hour LC50 at any time or place after mixing  with
 the receiving waters. The  24-hour average  of the  concen-
 tration  of these materials  should not exceed 0.05 of the
 LC50 after mixing.
   (b)   For  toxicants which  are persistent  or cumulative,
 the concentrations  should  not exceed  0.05  of the  96-hour
 LC50 at any time or place, nor should the 24-hour average
concentration exceed 0.01  of the 96-hour LC50.
   (c)  When two or more toxic materials  are present  at
the same time in the receiving water, it should be assumed
unless proven otherwise that their individual toxicities are
 additive and that some reduction in the permissible concen-
 trations is necessary. The amount of reduction required is
 a  function of both the number of toxic materials present
 and their concentrations in respect to  the permissible  con-
 centrations. The following relationship will  assure that the
combined amounts of the several substances do not exceed
a permissible concentration:
This formula may be applied where Ca, Cb, . . . Cn are the
measured or expected concentrations of the several toxic
materials in the water, and La, Lb, . .  . Ln are the respective
concentrations recommended or  those derived by  using
recommended application factors on  bioassays done under
local  conditions.  Should  the sum of the several fractions
exceed 1 .0,  a  local restriction on the concentration of one
or more  of the substances is necessary.
  C and L can be measured in any convenient chemical
unit as proportions of the LC50 or in any other desired way,
as long as the numerator and denominator of any single
fraction  are in the same units. To remove natural trace
concentrations and low nonadditive  concentrations from
the above formula, any single fraction which  has  a value
less than 0.2 should be removed from the calculation.

    Small  quantities of five toxicants are  measured in a
    stream  as follows:
       3  micrograms /liter (jug/1) of zinc; 3 jug/1 of phenol;
       3  fig/I of un-ionized ammonia as calculated from
       Figure  III- 10  (see Ammonia,  p. 186);  1  /ug/1 of
       cyanide; and  1 Mg/1 of chlorine.
    A bioassay with zinc sulphate indicates that  the 96-
    hour LC50 is 1.2 mg/1. The application factor  for
    zinc is 0.005;  therefore,  the allowable limit is 0.005 X
    1.2 = 0.006 mg 1. Initial bioassays  with phenol,  am-
    monia,  and cyanide  indicate that  the  recommended
    values are the safe concentrations stated in other sec-
    tions of the Report, not the fractions of LC50; so the
    limits are 0.1  mg/1, 0.02 mg/1, and 0.005 mg/1. The
    permissible limit  for chlorine (page 189) is 0.003 mg/1.
    Therefore, the total toxicity is estimated as follows for
    zinc, phenol, ammonia, cyanide,  and chlorine,  re-
    spectively :
0.003  0.003
                         0.003  0.001   0.001
           (1006  ~0     (XOT  O005   01)03
             = 0.5+0.03+0.15+0.2+0.33
    The second and third terms, i.e., phenol and ammonia,
    should be deleted since they are below the minimum
    of 0.2 for additive effects. This leaves 0.5+0.2+0.33 =
    1 .03, indicating that the total sublethal effect of these
    three toxicants  is slightly above the permissible level
    and that no higher concentration of any of the three
    is safe. Thus none can be added as a pollutant.

  Numerous activities initiated to maximize certain uses of
water resources often adversely affect water quality and
minimize  other uses. These activities have caused  both
benefit and harm  in terms of environmental quality. The
common forms  of physical  alteration of watersheds are
channelization,  dredging,  filling,  shoreline  modifications
(of lakes and streams), clearing of vegetation, rip-rapping,
diking, leveling, sand and gravel removal, and impounding
of streams!
  Channelization  is widespread throughout the United
States, and many studies have been conducted documenting
its effects. Channelization usually increases stream gradient
and  flow rates.  The quiet areas or  backwaters are either
eliminated or cut off from the main flow  of the stream, the
stream bed is  made  smooth,  thus reducing  the  habitats
available to benthic organisms, and surrounding  marshes
and swamps are more rapidly drained. The steeper gradient
increases velocity  allowing the stream to  carry a greater
suspended  load  and causing  increased turbidity. The rate
of organic waste transformation per mile is usually reduced,
and destruction of spawning and nursery areas often occurs.
Trautman  (1939),67 Smith and Larimore  (1963),65 Peters
and  Alvord  (1964),64  Welker  (1967),69  Martin (1969),63
and  Gebhards  (1970)68 have discussed the harmful effects
of channelization on some fish populations and the effect
on stimulation of less desirable  species.
  Dredging  undertaken   to  increase  water  depth  often
destroys highly productive habitats such  as marshes (Mar-
shall  1968,62 Copeland and  Dickens  1969).56 The  spoils
from dredging activities are frequently disposed of in other
shallow  sites causing further  loss of  productive  areas. For
example, Taylor and Saloman  (1968)66 reported that  since
1950 there has  been a 20 per cent decrease in surface area
of productive Boca Ciega Bay, Florida,  due  to fill areas.
It has become common practice to fill in marshy sites near
large metropolitan areas  (e.g., San Francisco Bay, Jamaica
Bay)  to  provide for  airport  construction  and industrial
  In addition to the material that is actually removed by
the dredging process,  a  considerable amount of  waste  is
suspended  in the water resulting in high turbidities (Mackin
1961).61 If the  dredged sediments are relatively  nontoxii
gross effects on motile aquatic life may not be noticeabL
but benthic communities ma-.y be drastically affected by tr
increased redeposition of silt (Ingle 1952).69
  In many instances either high nutrient or toxic sedimen
are suspended  or  deposited during  the dredging proces
This action may kill aquatic organisms by exposure to tl
toxicants present or by the depletion of dissolved oxyge
concentrations, or both. Brown and  Clark (1968)64 note
a dissolved oxygen reduction of 16 to 83 per cent whe
oxidizable sediments were rcsuspended. In many cases di
turbed sediments containing high nutrient concentratioi
may stimulate  undesirable  forms  of phytoplankton  c
Cladophora. Gannon and Beeton (1969)57 categorized harbc
sediments  in five groups. Those most severely  pollute
were toxic to various animals and did not stimulate growt
of phytoplankton. Other sediments were  toxic but stimi
lated plant growth. The least polluted sediments were n<
toxic  and  stimulated growth  of  phytoplankton  but nc
  Three basic aspects must be considered in evaluating tr.
impact of dredging  and disposal on  the aquatic enviroi
ment: (1) the amount and nature of the dredgings, (2) ti
nature and quality  of  the environments  of removal  an
disposal,  and (3) the ecological responses.  All vary wide!
in different environments, and it is not possible to identii
an optimal dredging and  disposal system. Consequent!'
the most  suitable program must be developed  for eac
situation.  Even in situations  where soil  is deposited  i
diked enclosures or used for fill, care must be  taken  1
monitor overflow,  seepage, and runoff waters for toxic an
stimulatory materials.
  Artificial impoundments may have serious environment;
impact on natural aquatic ecosystems. Dams  and otht
artificial  barriers  frequently   block  migration and  ma
destroy large areas of specialized habitat. Aquatic organise
are frequently  subjected  to  physical damage  if  they ai
allowed to pass through or over hydroelectric power uni
and  other man-made  objects when  properly   designe
barriers are not provided.  At large darns, especially thos
designed for hydroelectric power, water  drawn from tr

                                                                         Physical Manipulation of the Environment/125
pool behind the dam is frequently taken from great depths,
resulting in the release to the receiving stream  of waters
low in dissolved oxygen and excessively cold. This can be a
problem,  particularly  in  areas  where nonnative fish are
  Cutting  down  forests,  planting the land in crops,  and
partially covering the  surface of a watershed by building
roads, houses, and industries can have detrimental effects
on water ways. Wark  and Keller (1963)68 showed that in
the Potomac River Basin (Washington, D.C.) reducing the
forest cover from 80 per  cent to 20 per cent increased the
annual sediment yield  from 50 to 400 tons per square mile
per year. The planting of land in crops increased the sedi-
ment yield from  70 to 300 tons per square mile per year,
or a fourfold increase  as the land crops increased from 10
per cent to 50 per cent. Likens et al. (1970)60 showed that
cutting down the forest in the Hubbard Brook area (Ver-
mont) caused substantial changes in the streams. The sedi-
ment load increased fourfold over a period from May 1966
to May 1968. Furthermore, the particulate matter drained
from  the deforested  watershed  became  increasingly  in-
organic in content,  thus reducing the value of the sediment
as a food source. The nutrient content of the water was also
affected by  cutting down the forests. The nitrate concen-
tration increased from 0.9 mg/1  prior to  the cutting  of
vegetation  to 53 mg/1 two  years later.  Temperatures  of
streams in deforested areas were higher, particularly during
the summer months, than  those  of streams  bordered  bv
forests (Brown and  Krygier 1970).S5
   Prior  to  any  physical  alterations  of  a  watershed,  a
thorough investigation should be  conducted to determine
the expected balance between benefits and adverse environ-
mental effects.

                                SUSPENDED AND  SETTLEABLE  SOLIDS
   Suspended and settleable solids  include both  inorganic
and organic materials. Inorganic components include sand.
silt, and clay originating from erosion, mining, agriculture,
and areas  of construction. Organic matter may be com-
posed of a variety of materials added to the ecosystem from
natural and man-made sources. These inorganic and organic
sources are discussed in  the Panel  Report on Marine
Aquatic Life and Wildlife  (Section IV), and the effects of
land-water relationships are  described in  the  report on
Recreation and Aesthetics  (Section  I).


   Soil structure and drainage patterns, together with the
intensity and temporal distribution of rainfall that directly
affect the kind and amount of protective vegetative cover,
determine  the  susceptibility  of a  soil  to erosion.  Where
rain occurs more or less uniformly throughout  the year,
protective grasses, shrubs, or trees develop  (Leopold, et al.
1964).78 Where rainfall  occurs  intermittently, as  in  arid
areas, growth  of protective plants is limited  thus allowing
unchecked  erosion of soils.
   Wetting  and drying cause swelling and shrinking of clay
soils and leave the  surface susceptible to  entrainment  in
surface  water flows.  Suspended soil particle concentrations
in rivers, therefore,  are at their peak at the beginning  of
flood flows. Data  on the concentration of suspended matter
in most of  the significant streams of the United States are
presented in the U.S.  Geological  Survey Water  Supply
   Streams  transport boulders, rocks, pebbles, and sand by
intermittent rolling motions, or  by  intermittent suspension
and deposition as particles are entrained and later  settled
on the  bed. Fine particles  are held in suspension for long
periods, depending on the intensity of the turbulence. Fine
silt particles, when dispersed in fresh waters, remain almost
continuously suspended, and  suspension of dispersed  clay
mineral particles may be maintained even by the thermally
induced motions  in water.  These fine mineral particles are
the soil materials of greatest  significance to the  turbidity
values of a particular water.
  The suspended and settleable solids and the bed of a wall
body must be considered as interrelated, interacting part
For example, Langlois (1941)77 reported that in Lake Er
the average of 40  parts per million (ppm) of suspends
matter in the water was found to change quickly to moi
than  200 ppm with a strong wind. He further  explaine
that this increase is attributed to sediments resuspended 1:
wave action. These sediments  enter from streams or froi
shoreline erosion.
  Suspended clay mineral  particles are weakly cohesive i
fresh river waters having either unusually low dissolved sa
concentrations or high concentrations of multivalent cation
Aggregations of fine particles form and settle on the bed 1
form  soft fluffy deposits when  such waters enter a lake c
impoundment.  However,  clay mineral  particles are di,
persed or only weakly cohesive in most rivers.


  The composition and concentrations of suspended part
cles in surface waters are important because of their effec
on light penetration, temperalure, solubility products, an
aquatic life (Cairns  1968).7'2 The mechanical or abrasiv
action of particulate material is of importance to the highe
aquatic organisms,  such as mussels and  fish.  Gills may b
clogged  and  their  proper functions of respiration  an
excretion impaired. Blanketing  of plants and sessile anima
with  sediment as  well  as the blanketing  of importar
habitats, such as  spawning sites, can cause drastic change
in aquatic  ecosystems.  If sedimentation,  even of inei
particles,  covers  substantial amounts of organic materia
anaerobic conditions can occur and produce noxious gase
and  other objectionable characteristics, such as low dis
solved oxygen and decreases in pH.
  Absorption  of sunlight  by  natural  waters is strongl'
affected by the presence of suspended solids. The intensif
of light (/) at any  distance along a light ray (L) is, for ;
uniform suspension, expressed by the formula:
where 70 is the intensity just below the water surface (L = 0)

                                                                                    Suspended and Settleable Solids /127
k is the extinction coefficient for the suspended solids, and
c is the concentration of suspended solids. L can be related
to the  water  depth by the  zenith angle, i,  the  angle of
refraction, r, and the index of refraction of water, 1.33, by
Snell's rule:
                       sin r =
The depth, Z), is L cos r. Refraction makes the light path
more nearly  vertical  under  water than  the sun's rays,
except when the sun's rays are themselves normal to  the
water surface.
  The growth of fixed and suspended aquatic plants can
be limited by the intensity of sunlight. An example of the
decrease in the photic zone was calculated for San Francisco
Bay (Krone  1963),76  where k was  1.18X103  square centi-
meters per gram.  For a typical suspended solids  concen-
tration  of 50X10"6 grams per cubic centimeter, for an
algae requiring 20 foot candles or more for  its multipli-
cation, and under incident sunlight of  13,000 foot  candles
the photic zone did not exceed  1.1 meters. A reduction in
suspended solids concentration to 20 X 10~6 g/cm3 increased
the maximum depth of the photic zone to 2.8 meters.
  Because suspended  particles  inhibit the  penetration of
sunlight, water temperatures  are  affected, and increasing
turbidity results in increasing absorption near the water
surface  so that turbid waters warm more  rapidly at  the
surface  than do clearer waters.  Warming and the accom-
panying decrease in density stabilize water and may inhibit
vertical mixing. Lower oxygen  transfer value from air to
water results when surface waters  are heated. This action
combined with inhibited vertical mixing reduces the rate of
oxygen  transfer downward. Still or slowly moving  water is
most affected.
  The rate of warming, dT/dt, at any distance from  the
surface  along  a light path,  L, in water having  uniform
suspended material is
where p is the water density  and C is  the specific heat of
the water. This equation shows that an increase in suspended
sediment concentration increases the rate of warming near
the surface and decreases exponentially  with depth. The
biological significance of this relationship  is in the effect on
time of formation,  vertical distribution of thermal stratifi-
cation,  and stability of the  upper strata. Increasing tur-
bidity could change the stratification patterns of a lake and
thus change the temperature distribution, oxygen regime,
and composition of the biological communities.


  Suspended mineral particles have irregular, large surface
areas,  with electrostatic charges. As a consequence, clay
minerals may sorb cations, anions, and organic compounds.
Pesticides and heavy metals may be absorbed on suspended
clay particles and strongly held with them. The sorption
of chemicals by suspended  matter is particularly important
if it leads to a buildup of toxic and  radioactive materials
in a limited area with the possibility  of sudden  release of
these toxicants.  One such  example has been reported by
Benoit et al. (1967).70 Gannon and Beeton (1969)78 reported
that sediments with the following  characteristics dredged
from various harbors on the Great Lakes were usually toxic
to various organisms: COD 42,000  mg/1, volatile solids
4,000 mg/1, ammonia 0.075 mg/g, phosphate-P 0.65 mg/g.
  The capacity of minerals to hold dissolved toxic materials
is different for each  material and type of clay mineral. An
example illustrates the magnitudes of sorptive  capacities:
the cation exchange capacity (determined by the number
of negatively charged sites  on clay mineral surfaces)  ranges
from a few milliequivalents per hundred grams (me/100 g)
of mineral for kaolinite clay to more than 100 me/100 g for
montmorillonite clay. Typical estuarial sediments, which are
mixtures  of clay,  silt, and sand  minerals, have exchange
capacities ranging from 15 to 60 me/100 g (Krone 1963).76
The large  amounts of such  material that  enter  many
estuaries and lakes from tributary streams provide continu-
ally renewed sorptive capacity  that removes materials such
as  heavy metals,  phosphorus,  and radioactive ions.  The
average new sediment load flowing through the San Fran-
cisco Bay-Delta system, for  example, has a total  cation
exchange capacity of a billion  equivalents per year.
  The sorptive capacity effectively creates the large assimi-
lative capacity of muddy waters. A reduction in suspended
mineral  solids in surface waters can cause an increase in
the concentrations of dissolved toxic materials contributed
by  existing waste discharges.


  The surface of particulate matter may act as a substratum
for  microbial species, although the particle itself may  or
may not contribute  to their  nutrition. When  the presence
of particulate matter enables the environment  to support
substantial increased populations of aquatic microorganisms,
the dissolved  oxygen concentration,  pH, and  other char-
acteristics of the water are frequently altered.
  There are several ways in which  an excessive concen-
tration of finely divided solid matter might be harmful to
a fishery  in a river  or a lake  (European Inland  Fisheries
Advisory Commission, EIFAC  1965).73 These include:

     •  acting directly on fish swimming in water in which
       solids are suspended, either killing them or reducing
       their growth rate and resistance to disease;
     •  preventing the successful development of  fish eggs
       and larvae;

128/Section HI—Freshwater Aquatic Life and Wildlife
    •  modifying natural movements and migrations of fish;
    •  reducing the food available to fish;
    •  affecting efficiency in catching the fish.

  With respect to chemically inert suspended solids and to
waters that are otherwise satisfactory for the maintenance of
freshwater fisheries, EIFAC (1965)73 reported:

    •  there is no evidence that concentrations of suspended
       solids  less than 25 mg/1 have any harmful effects
       on fisheries;
    •  it should usually be possible to maintain  good or
       moderate fisheries in waters that normally contain
       25 to 80 mg/1 suspended solids;  other factors being
       equal, however,  the yield of fish from such waters
       might be somewhat lower than from those in the
       preceding category;
    •  waters  normally containing from 80 to 400  mg/J
       suspended solids  are unlikely to support good fresh-
       water  fisheries, although  fisheries may sometimes
       be found at  the  lower concentrations  within this
    •  only poor fisheries are  likely to be found in waters
       that normally contain more than 400 mg/1 suspended

  In addition,  although several thousand parts per million
suspended solids may not kill fish during several hours or
days exposure, temporary high concentrations should be
prevented in rivers where good  fisheries are to be main-
tained. The spawning grounds of most  fish should be kept
as free as possible from finely divided solids.
  While the low turbidities reported above reflected values
that should protect the ecosystem, Wallen (1951)80 reported
that fish  can  tolerate  higher concentrations. Behavioral
reactions  were not observed  until concentrations of tur-
bidity neared 20,000 mg/1, and in one species reactions did
not appear until turbidities reached 100,000 mg/1.  Most
species tested endured exposures of more than 100,000 mg/1
turbidity for a  week or longer, but these same fishes finally
died at  turbidities  of  175,000 to 225,000  mg/1. Lethal
turbidities caused the death of fishes within  15 minutes to
two hours exposure. Fishes that succumbed had opercular
cavities and gill filaments clogged with silty clay  particles
from the water.
  In  a study  of fish and macroinvertebrate  populations
over a four-year period in a stream receiving sediment from
a crushed limestone quarry, Gammon  (1970)74 found that
inputs that increased the suspended solids load less than
40  mg/1 (normal suspended solids was 38 to 41 mg/1 and
volatile suspended  solids 16  to 30 mg/1) resulted in a 25
per cent reduction in macroinvertebrate  density in  the
stream below the quarry. A heavy silt input caused  increases
of more than  120  mg/1 including some decomposition of
sediment, and  resulted in a 60 per cent reduction in density
of macroinvertebrates.  Population diversity  indices we
unaffected because  most species  responded  to  the sar
degree. The  standing crop  of fish decreased dramatical
when heavy  sediment occurred in the spring; but fish r
mained in pools during the summer when the input w
heavy and vacated the pools only after deposits of seclime
accumulated. After  winter floods removed sediment  d
posits, fish returned  to the pools and achieved levels of .
per cent of the normal standing crop by early June.
  Not all particulate matter affects organisms in the san
way.  For example,  Smith,  ei.  al.  (1965)79 found that tl
lethal  action of  pulp-mill  fiber  on walleye  fingerlin
(Stizostedion vitreum vitreuni) and fathead minnows (Pimepha,
promelas) was influenced by (he type of fiber. In  96-ho
bioassays, mortality  of the  minnows in 2,000 ppm suspe
sions  was 78 per cent in conifer groundwood, 34 per ce
in conifer kraft, and 4 per cent in aspen groundwood. Hit
temperatures and reduced dissolved oxygen coricentratio
increased the lethal action of fiber.
  Buck (1956)71 studied the  growth offish in 39 farm pone
having a wide range of turbidities. The ponds were cleart
of fish  and  then restocked with  largemouth  black ba
(Micropterus  salmoides),  bluegill (Lepomis macrothirus), ar
redear  sunfish  (Lepomis  microlophus). After  two growir
seasons the yields of fish were

    • clear  ponds (less  than 25 mg/1  161.5 Ib/acre
       suspended solids)
    • intermediate   (25-100   mg/1     94.0 Ib/acre
       suspended solids)
    • muddy  (more than 100 mg/1    29.3 Ib/acrc
       suspended solids)

   The rate of reproduction was also reduced by turbidit;
and the critical concentration for all three  species appeare
to be about 75-100 mg/1. In the same paper, Buck reporte
that largemouth black bass {Micropterus  salmoides), crappk
(Pomoxis), and channel catfish (Ictalurus punctatus) grew mor
slowly  in  a reservoir where  the  water  had an  averag
turbidity of  130 mg/1 than in another reservoir where th
water was always clear.
   Floating materials, including large objects as well as ver
fine substances, can adversely affect the activities of aquati
life. Floating logs shut out sunlight and interfere particular]
with surface  feeding fish. Logs may also  leach various type
of organic acids due to the action of water. If they hav
been  sprayed with pesticides  or treated chemically, theS'
substances may also leach into the water.  As the logs floa
downstream their bark often disengages  and falls to tfo
bed of the stream, disturbing benthic habitats. Aquatic life
is also affected by fine substances,  such as sawdust, peelings
hair  from tanneries, wood fibers, containers, scum,  oil
garbage,  and materials from untreated municipal and in
dustrial wastes, tars and greases, and precipitated chemicals

                                                                        Suspended and Settleable Solids/129

• The combined effect of color and turbidity should
  not change the compensation point more than
  10 per cent from its seasonally established norm,
  nor should  such a change place more than 10
  per cent of the biomass of photosynthetic orga-
  nisms below the compensation point.
Aquatic communities should be protected if the
following maximum concentrations of suspended
solids exist:

  High level of protection         25 mg/1
  Moderate protection             80 mg/1
  Low level of protection         400 mg/1
  Very low level of protection over 400 mg/1

  The true color of a specific water sample is the result of
substances in solution; thus it can  be measured only after
suspended material has been removed.  Color may be of
organic or mineral origin and may be the result of natural
processes as well  as  manufacturing operations. Organic
sources  include humic materials, peat, plankton, aquatic
plants, and tannins.  Inorganic substances  are largely me-
tallic, although iron and manganese, the  most important
substances, are usually not in  solution. They affect color as
particles. Heavy-metal complexes are frequent contributors
to the color problem.
  Many industries  (such as pulp and paper, textile, refining,
chemicals,  dyes  and  explosives, and  tanning)  discharge
materials that contribute to the color of water. •Conventional
biological waste treatment procedures  are frequently in-
effective in removing color. On the other hand, such treat-
ment processes  have caused an  accentuation of the level
of color during  passage  through  the  treatment  plant.
Physicochemical treatment processes are  frequently pre-
ferable to biological  treatment if color removal  is  critical
(Eye and Aldous 1968,81 King and  Randall 197083).
  The tendency for an accentuation of color to occur as a
result of complexing of a heavy metal with an organic sub-
stance may also lead to problems in surface waters.  A rela-
tively color-free discharge from a manufacturing operation,
may, upon contact with iron in a stream, produce a highly
colored water that would significantly affect aquatic life
(Hem I960,82 Stumm and Morgan  196286).
  The standard platinum-cobalt method of measuring color
is applicable to a wide variety of water samples (Standard
Methods  1971).85  However,  industrial  wastes frequen
produce colors dissimilar to the standard  platinum-cob
color, making the  comparison technique of limited vah
The standard unit of color in water is that level produc
by  1 mg/1 of platinum as chloroplatinate ion (Standa
Methods 1971).85 Natural  color in surface waters  rant
from less than one color unit to more than 200 in higt
colored bodies of water (Nordell 1961).84
  That light intensity at which oxygen production in pho
synthesis and  oxygen consumption by  respiration  of  t
plants concerned are equal is known as the compensati
point, and the depth at which the compensation point t
curs is called the compensation  depth. For a given body
water this depth varies with several conditions, includi
season, time of day, the extent of cloud cover, condition
the water, and the taxonomic composition of the flora
volved. As commonly used, che compensation point ref
to that  intensity of light which is such  that  the  plan
oxygen  production during the  day will  be  sufficient
balance the oxygen consumpiion during the whole 24-hc
period  (Welch 1952).87


  The combined effect of color and turbidity shou
not change the  compensation point more than
per cent from  its seasonally established norm, n
should such a change place more than 10 per cei
of the biomass of photosynthetic organisms belc
the compensation point.

                                            DISSOLVED  GASES

  Oxygen requirements of aquatic life have been extensively
studied.  Comprehensive  papers have  been  presented  by
Doudoroff and Shumway (1967),89 Doudoroff and Warren
(1965),91 Ellis (1937),93 and Fry (I960).94  (Much of the
research on temperature requirements also considers oxygen,
and references cited in  the discussion of Heat and Temper-
ature, p. 151,  are relevant here.) The most comprehensive
review yet to  appear has been written by Doudoroff and
Shumway  for  the  ivood and  Agriculture  Organization
(FAO)  of the United  Nations (1970).90 This FAO report
provides the most advanced summary of scientific research
on oxygen needs of fish, and  it has served as a basis for most
of the recommendations  presented  in this  discussion.  In
particular, it provided  the criteria for citing different levels
of protection  for fish,  for change from natural levels of
oxygen  concentration,  and for the actual numerical values
recommended. Much  of the text below has been quoted
verbatim or condensed  from  the FAO report. Its recommen-
dations  have been modified  in only two ways: the insertion
of a floor of 4  mg/1 as  a minimum, and the suggestion that
natural  minima be assumed to be equal  to  saturation
levels if the occurrence  of lower minima cannot be definitely
established.  Doudoroff and Shumway covered oxygen con-
centrations below the floor of 4 mg/1; however, the 4  mg/1
floor has been adopted in this report for reasons explained

Levels of Protection
  Most species of adult fish can survive at very low concen-
trations of dissolved oxygen.  Even  brook trout (Salvelinus
fontinalis) have been acclimated in the laboratory  to less
than 2 mg/1 of Oa. In natural waters, the minimum concen-
tration  that allows  continued existence of  a varied fish
fauna, including valuable food and game  species, is not
high.  This minimum is not above 4 mg/1 and may be much
  However, in evaluating criteria,  it  is not important to
know how long an animal can resist  death by asphyxiation
at low dissolved oxygen concentrations. Instead, data  on
the oxygen  requirements  for  egg development,  for newly
hatched  larvae, for normal growth and activity,  and for
completing all stages of the reproductive cycle are pertinent.
Upon review  of the available research, one fact becomes
clear: any reduction of dissolved  oxygen can  reduce the
efficiency of oxygen uptake by aquatic animals and hence
reduce their ability to meet demands of their environment.
There is  evidently no concentration level or percentage of
saturation to which the O2 content of natural  waters can
be reduced without causing or risking some  adverse effects
on the reproduction,  growth, and consequently, the  pro-
duction of fishes inhabiting those waters.
  Accordingly, no single, arbitrary recommendation can
be set for  dissolved oxygen concentrations that  will  be
favorable for all kinds of fish in all kinds of waters, or  even
one kind of fish in a single kind of water. Any reduction in
oxygen may be harmful by affecting fish production and
the potential yield of a fishery.
  The selection of a level of protection (Table 111-3) is a
socioeconomic  decision, not  a biological one.  Once the
level of protection is selected, appropriate scientific recom-
mendations may be derived from  the criteria presented in
this discussion.

Basis for Recommendations

  The decision to base the recommendations on O2  con-
centration minima, and  not  on  average concentrations,
arises from various considerations. Deleterious  effects on
fish seem to depend more on extremes than on averages.
For example,  the growth of young fish is slowed markedly
if the oxygen  concentration falls to 3 mg/1  for  part of the
day, even if it rises as high as 18 mg/1 at other times. It
could be an inaccurate and possibly controversial  task to
carry out the sets of measurements  required  to  decide
whether  a criterion based  on averages was being met.
  A daily fluctuation of O2 is to be expected where there is
appreciable  photosynthetic activity of aquatic plants.  In
such cases,  the minimum  O2  concentration will usually  be
found just before daybreak,  and sampling should be  done
at that time.  Sampling should also take into account the
possible differences in  depth  or  width of the water body.
The guiding principle should be to sample the places where

 132/Section HI—Freshwater Aquatic Life and Wildlife
aquatic organisms actually live or the parts of the habitat
where they should be able to live.
  Before recommendations are proposed, it is necessary to
evaluate criteria for the natural,  seasonal C>2 minimum
from which the recommendations can be derived. Natural
levels are assumed to be the saturation levels,  unless scien-
tific data show that  the natural levels were already low in
the absence of man-made effects.
  Certain waters in  regions of low human populations can
still be adequately studied in their natural or  pristine con-
dition. In these cases the minimum C>2  concentration at
different seasons, temperatures, and stream discharge  vol-
umes can be determined by direct observation.  Such ob-
served conditions can also be useful in estimating seasonal
minima  in similar waters in similar geographical regions
where natural levels can no longer  be observed because of
waste discharges or other man-made changes.
  In many  populated regions, some or  all of the streams
and lakes have been  altered.  Direct  determination of
natural minima may no longer be  possible. In these cases
the assumption of year-round saturation  with O2 is made
in the absence  of other evidence.
  Supersaturation of water  with  dissolved  oxygen may
occur as the result of photosynthesis by aquatic vegetation.
There is  some  evidence  that this  may  be deleterious to
aquatic animals because  of gas bubble disease (see Total
Dissolved Gases, p. 135).
  Despite the statements in previous paragraphs that there
is no single O2 concentration which is favorable to all species
and ecosystems, it is obvious  that  there are,  nevertheless,
very low C>2 concentrations that are unfavorable  to almost
all  aquatic  organisms.  Therefore,   a floor of 4 mg/1  is
recommended except in situations where the  natural level
of dissolved oxygen  is less than 4 mg/1  in which case no
further depression is desirable. The  value of 4  mg/1 has
been selected  because  there  is  evidence of  subacute or
chronic damage to  several fish below this concentration.
Doudoroff and Shumway  (1970)90  review  the  work of
several authors as given  below, illustrating such damage.
Fathead minnows  (Pimephales promelas)  held at 4 mg/1
spawned  satisfactorily;  only  25 per  cent  of  the  resultant
fry  survived for 30 days,  compared to 66 per cent survival
at 5 mg/1. At  an oxygen level of  3 mg/1, survival of fry
was even further  reduced to 5  per cent (Brungs 1972101
personal communication). Shumway  et al. (1964)98 found  that
the dry weight of coho salmon (Oncorhynchus kisutch} aleviris
(with yolk sac removed) was reduced by 59 per cent when
they had been  held at 3.8 mg/1 of oxygen,  compared to
weights of the controls. The embryos of sturgeon (Acipenser)
suffered  complete mortality  at oxygen  concentrations of
3.0 to 3.5 mg/1, compared to only 18 per cent mortality at
5.0  to 5.5 mg/1  (Yurovitskii  1964).10°  Largemouth  bass
(Micropterus salmoides) embryos reared at 25 C showed  sur-
vival equal to controls only at oxygen levels above 3.5 mg/1
(Dudley 1969).92 Efficiency of food conversion by juvenile
bass was nearly independent of Oa at 5 mg/1 and higl
but growth rate was reduced by 16.5 per cent at 4 mi
and  30 per cent at 3 mg/1 (Stewart et al. 1967)." Sim
reductions in growth  of underyearling coho  salmon
curred  at  the  same C>2 concentrations (Herrmann et
1962).95 Although  many other experiments  have she
little  or no damage to performance  of fish at 4 mg/1.
lower, the evidence given above shows appreciable efTi
on embryonic and juvenile survival and growth for sev<
species of fish sufficient to justify this value.

Warm- and Coldwater Fishes
  There are  many associations and types of fish fai
throughout the country. Dissolved oxygen criteria for cc
water fishes and warmwater game  fishes are conside
together in this report. There  is no evidence  to sugi
that the more  sensitive warmwater species have  lower
requirements than the  more sensitive coldwater fishes. "
difference in O2 requirements is probably not greater tl
the difference of the solubility of C>2 in water at the m;
mum temperatures to  which these  two kinds of fish
normally  exposed in summer  (Doudoroff and Shumv
1970).90 In warmwater regions, however, the  variety
fishes and fish habitats is relatively  great, and  there
many warmwater species that are exceedingly toleranl
O2 deficiency.

Unusual Waters
   There are certain types of waters that naturally have 1
oxygen content, such as the "black waters" draining swar
of the Southeastern United States.  (Other examples inch
certain deep ocean waters and eutrophic waters that supp
heavy biomass, the respiration of which reduces O2 cont
much of the time.) A special situation prevails in  the di
layers (hypolimnion) of some lakes. Such layers do not t
with  the surface layers for extended  periods and may h.
reduced C>2, or almost  none. Fish cannot live in  the di
layers of many such lakes during  a large part of the ye
although  each lake of  this kind must be considered  a
special case. However,  the recommendation that no oxyg
consuming  wastes should be released into the deep lay
still applies, since there may be no opportunity for reaerat
for an entire season.

Organisms Other Than Fish
   Most research concerning oxygen requirements for fre
water organisms deals with fish; but since fish depend up
other aquatic species for food,  it is  necessary to consii
the O2 requirements of these organisms. This Section ma
the assumption that the C>2 requirements of other  compc
ents of the aquatic community are  compatible  with f
(Doudoroff and Shumway 1970) .90 There are certain exci
tions where exceedingly important invertebrate organis
may be very sensitive to lov/ O2,  more sensitive than the f
species in that habitat  (Doudoroff and Shumway  1970

                                                                                                          Dissolved Gases/133
The situation is somewhat  more complicated for inverte-
brates and aquatic plants, inasmuch as organic pollution that
causes reduction of O2 also directly increases food  material.
However, it appears equally true for sensitive invertebrates
as for fish  that  any reduction  of dissolved O2 may have de-
leterious effects  on their production. For example, Nebeker
(1972)97 has found that although a certain mayfly (Ephemera
simulans) can  survive  at  4.0 mg/1 of  oxygen for four days,
any reduction of oxygen below saturation causes a decrease
in successful transformation of the  immature  to  the adult

Salmonid Spawning

  For spawning of salmonid fishes during the  season when
eggs are  in the gravel, there are even greater requirements
for O.i than  those  given  by the high level of protection.
(See Table III-3 for  description of levels.)  This is because
the water associated with the gravel may contain less oxygen
than  the water in  the stream above the gravel.  There  is
abundant evidence that salmonid eggs are adversely affected
in direct proportion to reduction in O2. The oxygen criteria
for eggs should be about  half way between the nearly
maximum  and high levels of protection.
 TABLE III-3—Guidelines for Selecting Desired Type and
  Level of Protection of Fish Against Deleterious Effects of
              Reduced Oxygen Concentrations
 Level of protection
                 Intended type of protection
                                            Possible application
Nearly Maximum"   For virtually unimpaired productivity and
              unchanged quality of a fishery.
High          Not likely to cause appreciable change in
              tbe ecosystem, nor material reduction of
              fish production. Some impairment is
              risked, but appreciable damage is not to
              be expected at ttiese levels of oxygen.
Moderate        Fisheries should persist, usually with no
              serious impairment, but with some de-
              crease in production.
Low           Should permit the persistence of sizeable
              populations of tolerant species and suc-
              cessful passage of most migrants'1. Much
              reduced production or elimination of sen-
              sitive fish is likely.
Appropriate for conservation areas, parks, and
 water bodies of high or unique value. Re-
 quires, practically speaking, that little or no
 deoxygenatmg wastes be added to natural
 waters. Nor must there be any activities
 such as unfavorable land use which would
 reduce 02 levels.
Could be appropriate for fisheries or aquatic
 ecosystems of  some importance, which
 should not be impaired by other uses of

Could be used for fisheries which are valued,
 but must co-exist with major industries or
 dense human population
Appropriate for fisheries that have some com-
 mercial or recreational value, but are so
 unimportant compared  with other water
 uses, that  their maintenance cannot be a
 major objective ol pollution control.
This type of protection should however, pro-
 vide lor survival of sensitive species m adult
 or subadult life stages for short periods
 during the  year, if oxygen levels at other
 times are satisfactory for growth, reproduc-
 tion, etc.
0 Note that there could be > higher level of protection that would require oxygen to be near natural level at all times,
whereas nearly maximum requires only that oxygen should not fall below the lowest level characteristic of the season.
 k But will not protect migrating salmonids, which would requite it least a Moderate level of protection, for zones of
Interaction with Toxic  Pollutants or Other Environmental

   It  is known that  reduced  oxygen levels increase the
toxicity of pollutants. A method  for  predicting this inter-
action  has been given by Brown (1968),88 and a theoretical
background  by Lloyd  (1961).96 The disposal of toxic pol-
lutants must be controlled  so that their concentrations will
not  be unduly harmful at prescribed acceptable  levels  of
O2,  temperature, and  pH. The  levels  of oxygen  recom-
mended in this Section are independent of the presence  of
toxic wastes, no matter what the  nature of the  interaction
between these toxicants and O2 deficiencies. Carbon dioxide
is an  exception,  because its concentration  influences the
safe level of oxygen.  The recommendations  for  O2 are
valid  when  the  CO2  concentration  is within the limits
recommended  in  the  section on CO2.

Application  of Recommendations

   As previously stated, the recommendations herein differ
in two important respects from   those widely  used. First,
they are not  fixed values independent of natural  conditions.
Second, they offer a choice of different levels of protection
of fishes, the selection of any one of  which is  primarily a
socioeconomic  decision, not a biological one.
   Table  111-4 presents  guidelines for  the protection  of
fishes at each  of four levels.  Each column shows the level
to which the dissolved O2 can be  reduced  and still  provide
the stated level of protection for local fisheries. The values
can  be derived from the equations given in the recommen-
dations. These equations have been  calculated to fit the
curves  shown in the figure on page 264  of Doudoroff and
Shumway (1970),90 which  serve as the basis of  the  recom-
mendations.  To use  Table 111-4,  the  estimated  natural
seasonal minimum should first be determined on the basis
of available  data or  from  expert judgment.  This  may  be
taken  to  be  the minimum  saturation  value for the  season,
unless  there  is scientific  evidence that losses of O2 levels
prevailed  naturally.  The  word   "season" here means  a
period  based on local climatic and hydrologic  conditions,
during which the natural thermal and dissolved O2 regime
of a stream  or lake can  be expected  to  be fairly uniform.
Division of the year into equal three-month  periods, such
as December-February, March-May, is  satisfactory. How-
ever, under special conditions, the designated seasons could
be periods longer or shorter than  three months, and could
in fact  be  taken as individual months. The selected periods
need not be  equal in  length.
  When the  lowest natural value for the  season has  been
estimated, the  desired kind and level of protection  should
then be selected according to the guidelines in Table 111-3.
The recommended minimum level of dissolved oxygen may
then be found  in the selected column of Table 111-4, or as
given by the  formula  in the recommendation.

 134/Section III—Freshwater Aquatic Life and Wildlife
    TABLE III-4—Example of Recommended Minimum
           Concentrations of Dissolved Oxygen
 Estimated natural
 seasonal minimum Corresponding temperature of
Recommended minimum concentrations of 02 for
     selected levels of protection
bwllbvlluauull Ul
oiysen in water
(») («)
46C(a) (115FX»)
36C (96. !F)
27. 5C (>1. 5F)
21C (69. 8F)
16C (60. 8F)
7.7C (45. 9F)
1.5C (34. 7F)
High Moderate
4.7 4.2
5.6 4.8
6.4 5.3
7.1 5.8
7.7 6.2
8.2 6.5
8.9 6.8
9.3 6.8
 " Included to cover waters that are naturally somewhat deficient in 0«_ A saturation value of 5 me/I might be
found in warm springs or very saline waters. A saturation value of 6 mg/1 would apply to warm sea water (32 C=
90 F).
 Note: The desired kind and level of protection of a given body of water should first be selected (across head of
table). The estimated seasonal minimum concentration of dissolved oxygen under natural conditions should then be
determined on the basis of available data, and located in the left hand column of the table. The recommended mini-
mum concentration of oxygen for the season is then taken from the table. All values are in milligrams of 02 per
ter. Values for natural seasonal minima other than those listed are given by the forntu la and qualifications in the
section on recommendations.
    • It is desired to  give moderate protection to trout
    (Salvehnus fontinalis)  in a  small  stream during  the
    summer. The maximum summer temperature is 20 G
    (68 F); the  salt content of the water is low and  has
    negligible effect on the oxygen saturation value. The
    atmospheric pressure is  760 millimeters (mm) Hg.
    Oxygen saturation is therefore 9.2  mg/1. This is as-
    sumed to be  the natural seasonal  minimum  in  the
    absence of evidence  of lower natural concentrations.
    Interpolating from  Table III-4 or  using the recom-
    mended formula, reveals a minimum permissible con-
    centration of oxygen during the summer of 6.2 mg/1.
    If a high level of protection had been selected,  the
    recommendation would have been  7.8  mg/1.  A low
    level of protection, providing little or no protection
    for trout but some for more tolerant fish, would require
    a recommendation of 4.5 mg/1.  Other recommen-
    dations would  be calculated in a similar  way for other
    • It is decided to  give moderate  protection to large-
    mouth bass (Micropterus salmoides)  during the summer.
    Stream temperature  reaches a maximum  of  35  C
    (95 F) during  summer, and lowest seasonal saturation
    value is accordingly 7.1 mg/1.  The recommendation
    for minimum oxygen concentration is 5.4 mg/1.
    • For  low protection of fish  in summer in the same
    stream  described above  (for  largemouth bass),  the
    recommendation would be 4.0 mg/1, which  is also the
    floor value recommended.
    • It is desired to protect marine fish in full-strength
    sea water (35 parts per thousand salinity) with a maxi-
    mum seasonal temperature of 16 C  (61  F).  The satu-
    ration value of 8 mg/I is assumed to be the natural dis-
    solved oxygen minimum for the season. For a high level
    of protection,  the recommendation is 7.1 mg/1, for a
    moderate level of protection it  is  5.8 mg/1,  and for a
    low level of protection it is 4.3 mg/1.
  It should be stressed that the recommendations are
minimum values for any time during the same season.

  (a) For nearly maximal protection  of  fish  a:
other aquatic life, the minimum dissolved oxyg
in any season (defined previously) should not
less than the estimated natural seasonal minimu
concentration (defined previously) characteristic
that body of water for the same season.  In es
mating natural minima, it is assumed that watt
are  saturated, unless there is  evidence that th
were lower in the absence of man-made influenc<
  (b) For a  high  level of protection  of fish, t
minimum dissolved oxygen concentration in ai
season  should not be less than that given by tl
following formula  in  which  M = the estimat
natural seasonal minimum  concentration  cha
acteristic of that body of water for the same seaso
as qualified in (a):

         Criterion* = 1.41M-0.0476M2-1.11

  (c) For a moderate level of protection of fish, tl
minimum dissolved oxygen concentration in ai
season  should not  be less than  is given by tl
following formula with qualifications as in (b):

        Criterion* = 1.08M - 0.0415M2 - 0.202

  (d) For a  low  level of protection  of fish, tl
minimum 02 in any season should not  be less ths
given by the following formula with qualificatioi
as in (b):
        Criterion * = 0.674M-0.0264M2+0.577
  (e) A floor value of 4 mg/1 is recommended excej
in those situations where the natural  level of di
solved oxygen is less than 4 mg/1, in which case r
further depression is desirable.
  (f) For  spawning grounds of salmonid fishe
higher  O2 levels are required as  given in the follov
ing formula with qualifications as in (b):
        Criterion* = 1.19M -0.0242M2-0.418
  (g) In stratified eutrophic and dystrophic lake
the  dissolved oxygen requirements may not app]
to the hypolimnion  and such lakes should be cor
sidered on a case by case basis. In other stratifie
lakes, recommendations (a), (b), (c), and (d) applj
and if the oxygen is below 4 mg/1, recommendatio
(e) applies. In unstratified lakes recommendation
apply to the entire circulating  water mass.
  (i) All the foregoing recommendations apply t
all waters except waters designated as mixing zont
                              * All values are instantaneous, and final value should be expressc
                            to two significant figures.

                                                                                                  Dissolved Gases/ \ 35
(see  section on Mixing Zones p. 112). In locations
where supersaturation occurs, the increased levels
of oxygen should conform to the recommendations
in the discussion of Total Dissolved Gases, p. 139.

  Excessive total dissolved gas pressure (supersaturation) is
a relatively new aspect of water quality.  Previously, super-
saturation was believed to be a problem that was limited to
the water  supplies of fish culture facilities (Shelford and
Alice 1913).135 Lindroth  (1957)126 reported that spillways
at hydroelectric dams in Sweden caused supersaturation,
and recently Ebel (1969)112 and Beiningen  and Ebel (1968)103
established that spillways at dams caused gas bubble disease
to be a limiting factor for aquatic life in the Columbia and
Snake Rivers. Renfro (1963)133  and others reported  that
excessive algal  blooms  have  caused  gas  bubble disease in
lentic water. DeMont and Miller (in press)110 and  Malous
et al. (1972)127 reported gas bubble disease among fish and
mollusks living in the heated effluents  of steam generating
stations. Therefore,  modified dissolved gas pressures as a
result  of dams,  eutrophication,  and  thermal  discharges
present a widespread potential for adversely affecting  fish
and  aquatic invertebrates.  Gas bubble  disease  has been
studied frequently since  Gorham (1898,119  1899120) pub-
lished his initial papers, with the result that general knowl-
edge  of the causes,  consequences, and adverse levels  are
adequate to evaluate criteria for this  water quality char-
  Gas bubble disease is caused by excessive total dissolved
gas pressure but it is not caused by the  dissolved nitrogen  gas
alone  (Marsh  and Gorham  1904,128 Shelford and  Alice
1913,135Englehorn 1943,115 Harvey et al. 1944a,m Doudoroff
1957,m Harvey and  Cooper 1962).123  Englehorn (1943)115
analyzed the  gases  contained  in  the  bubbles  that were
formed in fish suffering from gas bubble  disease and found
that their gas composition was essentially identical to  air.
This was confirmed by Shirahata  (1966).13C
Etiologic Factors
  Gas bubble disease (GBD) results when the uncompen-
sated total gas pressure is greater in the  water than in  the
air, but several  important factors influence the etiology of
GBD.  These factors  include: exposure time and physical
factors  such as  hydrostatic  pressure;  other compensating
forces  and  biological factors such as species  or  life stage
tolerance or levels of activity; and  any  other factors that
influence gas solubility. Of these  factors  perhaps none  are
more commonly misunderstood than the physical  roles of
total dissolved gas pressure* and hydrostatic pressure. The
following discussion is intended to clarify these roles.
  Each component gas in air exerts a measurable pressure,
and  the sum of these pressures constitutes atmospheric  or
barometric pressure, which is equivalent per unit of surface
area at  standard conditions to a  pressure  exerted  by  a
column  of mercury  760mm high or  a  column of water
about  10 meters  high (at sea level, excluding water vapor
pressure). The pressure of an individual gas in air is called
a partial pressure,  and in  water it is called  a tension; both
terms are an acknowledgement that the pressure of an indi-
vidual gas is only part of  the total  atmospheric pressure.
Likewise, each component  gas will dissolve in water inde-
pendently of all other gases, and when at equilibrium with
the air, the pressure  (tension) of a specific dissolved gas is
equivalent to its partial pressure in the air. This relationship
is evident in Table 111-5 which lists the main constituents
of dry air and their approximate partial pressures at  sea
  When supersaturation  occurs, the  diffusion pressure im-
balance  between the  dissolved gas phase and the atmos-
pheric phase favors a net  transfer of gases from the water to
the air. Generally this transfer cannot be accomplished fast
enough by diffusion alone to prevent the formation of gas
bubbles. However, a gas  bubble cannot form in the water
unless  gas nuclei are  present (Evans and Walder  1969,116
Harvey et al. 1944b122) and unless  the total dissolved gas
pressure exceeds the sum of the compensating pressures such
as hydrostatic pressure. Additional compensating pressures
include  blood  pressure  and viscosity, and  their benefits
may be significant.
  Gas  nuclei are probably  unavoidable in  surface water
or in animals, because such nuclei are generated  by any
factor  which decreases gas solubility, and because extreme
measures are required to dissolve gas nuclei  (Evans and
Walder 1969;116 Harvey et al. 1944b).122 Therefore, hydro-
static pressure  is  a major preventive factor in gas bubble
  The effect of hydrostatic pressure is to oppose gas bubble
formation. For example,  one cannot blow a  bubble out of
a tube immersed  in water until the gas pressure in the tube
slightly exceeds the  hydrostatic pressure  at  the end of the
tube. Likewise a bubble  cannot form  in water, blood,  or

TABLE JH-5—Composition of Dry Air and Partial Pressures
               of Selected Gases at Sea  Level
         Molecular" percentage  Times atmospheric pressure   Individual gas'1 pressure in air or
            in dry air                           water at sea level
AT. .
Ne .
78.084 X760mmH|
= 593.438 mm Ht
  * In this Section gas tension will be called gas pressure and total
gas tension will be called total dissolved gas pressure (TDGP). This
is being done as a descriptive aid to readers who are not familiar with
the terminology and yet need to convey these principles to laymen.
                                           759.9927 mm Ht
 « Glueckaul (19S1"»).
 * At standard conditions iicludinj corrections for water vapor pressure.

136/'Section III—Freshwater Aquatic Life and Wildlife
tissue until the total gas pressure therein exceeds the sum of
atmospheric pressure (760mm Hg) plus hydrostatic pressure
plus  any  other  restraining  forces.  This  relationship  is
illustrated  in Figure III-l which shows, for example, that
gas bubbles could form in fresh water to a depth of about
one meter  when the total dissolved gas pressure is equal to
1.10  atmospheres;  but they  could not form below that
  Excessive total dissolved gas pressure relative to ambient
atmospheric pressure, therefore, represents a greater threat
to aquatic organisms in the shallow but importantly pro-
ductive littoral zone  than in the deeper sublittoral zone.
For example, if fish or their food organisms remain within a
meter of the surface in water having a total dissolved gas
pressure of 1.10 atmospheres, they are theoretically capable
of developing gas bubble disease,  especially if their body
processes further decrease gas solubility by such  means as
physical activity, metabolic heat, increased osmolarity, or
decreased blood pressure.
  Hydrostatic pressure only opposes bubble formation;  it
does not decrease the kinetic energy of dissolved gas mole-
cules except at extreme pressures. If this were not the case,
aerobic animal life would be eliminated at or below a water
depth equivalent to the pressure of oxygen,  because there
would be  no  oxygen pressure to drive Oo across the gill
membrane and thence into the blood. For a more detailed
discussion  of  this subject, the reader is referred to Van
Liere and Stickney's  (1963)138 and  Randall's  (1970a)131
excellent reviews.
    1 00        1 10       1  20       1 Vi      1.40

                  Tnl.i! DissoKeel Gas PH'SSUIL HI \tmosphcics
                                                      1 5(1
  A final example will clarify the importance of total c
solved gas pressure. Eutrophic lakes often become sup
saturated with photosynthetic dissolved oxygen,  and si.
lakes commonly approach  (or  exceed) 120  per cent
saturation values  for oxygen.  But this  only represents
additional dissolved gas  pressure of  about  32mm  1
(O2= 159.19 mm HgX0.2==31.83 mm Hg) which equal;
  760_mm Hg+31.83mmHg
         760 rnm Hg
= 1.041 atmospheres of tote
    dissolved gas pressure
FIGURE III-l—Relationship of Total Dissolved Gas Pressure
to Hydrostatic Pressure in Preventing Gas Bubble Formation
This imbalance apparently can be compensated in part
metabolic  oxygen  consumption,  blood pressure,  or  bo
On  the  other hand, a  1.000-fold increase in  the  ne
saturation  level would only increase the total dissolved t
pressure by about 1.8 mm Hg or:

       1.8 mm Hg+ 760 mm Hg
       	-- = 1.002 atmospheres
             760 mm Hg

This would not cause gas bubble disease.
  The opposite situation can occur in spring water, \vh(
dissolved oxygen pressure is low and dissolved nitrogen a
other gas pressures are high. In an actual case  (Schneic
personal communication).14'1 dissolved nitrogen was reported
be 124 per cent of its air saturation value, whereas oxyg
was 46 per cent of its air saturation value;  total gas pressi.
was  1.046  of dry atmospheric1 pressure. Fish were living
this  water, and  although  they  probably suffered  frc
hypoxia, they showed no symptoms of gas bubble disease
  How  dissolved gases come out of solution and for
bubbles  (cavitate) is a basic  physical and physiologic
topic which is only summarized here. Harvey etal. (1944b)
determined that bubble formation is promoted by bounda
zone or surface interfaces which reduce surface  tension ai
thereby  decrease the dissolved gas pressure required i
cavitation.  For this  reason,  one  usually  sees gas bubb
forming first and growing fastest on  submersed interfao
such as tank walls, sticks, or the external surfaces of aqua
  Gas nuclei are apparently required  for bubble formatio
and these are considered to  be ultra micro bubbles (Eva
and Walder 1969).11'1 These  nuclei apparently represent <
equilibrium between the extremely high compressive eneri
of surface tension and the pressure of contained gases. Lai
of gas nuclei probably accounts for instances when extreme
high  but uncompensated  dissolved gas pressures failed
cause  bubble formation  (Pease and  Blinks 1947,13° Her
mingsen 1970).124 Gas nuclei are produced by anything th
decreases gas  solubility or surface tension  (Harvey et £
1944b,122 Hills 1967,125 Evans and Walder  1969)116 and the
can be eliminated at least temporarily by  extremely  hie
pressure which drives them back into solution  (Evans an
Walder  1969).116
   Possible causes of gas nuclei formation in organisms ii
elude negative pressures in skeletal or cardiac muscle durhi

                                                                                                 Dissolved Gases/137
pronounced activity (Whitaker et al. 1945),141 eddy currents
in the blood vascular system, synthetic or biologically pro-
duced surface-active compounds, and possible salting-out
effects during  hemoconcentration  (as in  saltwater adap-
tation). Once a bubble has formed, it grows via the diffusion
of all gases into it.
  Many factors influence the incidence and severity of gas
bubble, disease. For example, the fat content  of an animal
may influence its susceptibility. This has not  been studied
in fish, but Boycott  and Damant (1908),106 Behnke  (1942),102
and  Gersh  et  al.  (1944)117 report that fat mammals are
more susceptible than lean  mammals to  the "bends" in
high-altitude decompression. This may be particularly sig-
nificant to non-feeding adult Pacific  salmon  which  begin
their spawning run with considerable  stored fat. This may
also  account in part for differences  in the  tolerances of
different age groups or  fish species.  Susceptibility to gas
bubble disease is unpredictable among wild fish, particularly
when they are free  to change their water depth and level of

Gas  Bubble Disease Syndrome and Effects

  Although the literature documents  many occurrences of
gas bubble disease, data are  usually missing for several
important  physical factors,  such as hydrostatic  pressure,
barometric  pressure, relative humidity,  salinity, temper-
ature,  or other factors leading  to calculation of total dis-
solved gas pressure.  The most frequently reported parameter
has been  the  calculated  dissolved nitrogen  (Nj) concen-
tration or  its  percentage saturation  from  which one can
estimate the pressure of inert gases. Thus  the reported N»
values provide only a general indication of  the total dis-
solved gas pressure, which  unfortunately tends to convey
the erroneous concept that N2 is the instigative or only sig-
nificant factor in gas bubble disease.
  Gas bubbles probably form first on  the external surfaces
of aquatic life,  where total hydrostatic pressure is  least and
where an interface  exists. Bubbles within the body of ani-
mals  probably form later at low dissolved gas pressures,
because blood pressure and other factors may provide ad-
ditional resistance  to bubble formation. However, at high
dissolved gas pressure (>1.25 atm) bubbles  in the  blood
may he the first recognizable symptom (Schneider personal
communication).1''* In the case of larval fishes,  zooplankton,
or other small forms of aquatic life,  the effect of external
bubbles may be a blockage of the flow of water across the
gills  and asphyxiation or a change in buoyancy (Shirahata
1966).136  The  latter probably causes additional energy
expenditure or floatation, causing potentially lethal exposure
to ultraviolet radiation or potential predation.
  The direct internal effects of gas bubble disease  include a
variety of symptoms that  appear to be related primarily to
the level of total dissolved gas pressure, the exposure  time,
and  the in vivo location of lowest compensatory pressure.
  The following is a resume of Shirahata's (1966)136 results.
As the uncompensated total dissolved gas pressure increases,
bubbles begin to appear on the fish, then within the skin,
the roof of the mouth, within the fins, or within the ab-
dominal cavity. Gas pockets may also form behind the eye-
ball  and  cause an  exophthalmic "pop-eyed" condition.
Probably gas emboli  in  the  blood are  the last  primary
symptoms  to develop, because blood pressure and plasma
viscosity oppose bubble formation. At some as yet undefined
point, gas  emboli become sufficiently  large  and  frequent
to cause hemostasis in blood vessels,  which in turn may
cause extensive  tissue damage or complete  hemostasis  by
filling the  heart chamber with gas.  The latter is the usual
direct cause of death.
  Exophthalmus or  "pop-eye" and eye  damage can  be
caused  by several factors other than  gas bubble disease
and one should be duly cautious when tempted  to diagnose
gas bubble disease based solely on these criteria. While the
above symptoms can be caused by  excessive dissolved gas
pressure (Wcstgard  1964),140  they can also  be caused  by
malnutrition, abrasion, and possibly by infection.  Unfortu-
nately there is no known definitive  way to distinguish be-
tween latent eye damage caused  by previous exposure to
excessive dissolved gas pressure and  other causes.
  Secondary,  latent,  or  sublethal  effects of gas bubble
disease in fish include promoting other diseases,  necrosis, or
other tissue changes,  hemorrhages,  blindness,  and repro-
ductive failure  (Harvey  and Gooper 1962,123 Westgard
1964,140 Pauley  and  Nakatani  1967,129 and  Bouck  et  al.
1971).10'" There is no known evidence  that supersaturation
causes a nitrogen narcosis in fish (such as can be experienced
by scuba clivers), as this requires high dissolved gas pressures
probably above  10 atm. However, one can expect  that fish
afflicted  with gas bubble disease  or the  above secondary
effects might have their normal behavior altered.
  There is no definitive  evidence  that fishes  can detect
supersaturation  (Shelford and Alice 1913),13r' or that they
actively avoid it by seeking hydrostatic pressure  compen-
sation (Ebel  1969).112 However, the potential capacity to
avoid  supersaturation or  to  compensate  by sounding is
limited among  anadromous  species by   the necessity  of
ascending  their  home river and by dams with relatively
shallow fish ladders. This may also  apply to other species
that reproduce in or otherwise live in shallow-water niches.
Physiological adaptation to supersaturation seems unlikely,
and this contention is supported by the preliminary studies
of Coutant and Genoway (1968).109
  Interaction between gas bubble  disease  and other stresses
is highly likely but not clearly established. Fish were more
susceptible to a given level of total dissolved gas  pressure
when wounded  (Egusa 1955).114 The thermal tolerance of
Pacific  salmon was  reduced  when  N2 levels were 125  to
180 per cent in the  case of juveniles (Ebel et al.  1971),U3
and when N2 levels were > 118 per cent in the case of adults
(Coutant and Genoway 1968).ln9 Chemicals or other factors

 \38/Section HI—Freshwater Aquatic Life and Wildlife
that influence body activity or cardiovascular activity may
also influence blood pressure (Randall 1970b),132 and this
would be expected to influence the degree to which the dis-
solved gas pressure is in excess, and hence the tolerance to
gas bubble disease.
  Variation in biological response  is a prominent aspect of
gas bubble disease, which should not be surprising in view
of the numerous influential factors. Some of this variation
might be explained by physiological differences between
life stages  or species,  degree of fatness, blood pressure,
blood  viscosity, metabolic  heat, body size, muscular ac-
tivity,  and  blood osmolarity. For example, susceptibility to
gas bubble disease may be inversely related to blood (or
hemolymph) pressure.  There is wide  variation in  blood
pressure between  life stages, between fish species, and be-
tween invertebrate species. Based on aortic blood pressures
alone, one can hypothesize that largemouth bass (Mwropterus
salmoides) might be more susceptible to gas  bubble disease
than chinook salmon (Oncorhynchus tshawytscha) if other fac-
tors are equal.  This contention is also supported  by the
observations that gas bubbles form in the blood of bullfrogs
more  easily  than  in rats  (Berg  et al.  1945),104 possibly
because  of differences  in  blood  pressure  (Brand  et  al.
  Tolerance  to supersaturation also varies  between  body
sizes or life stages; Shirahata (1966)136 relates this, in part,
to  an increase  in cardiac  and skeletal  muscle  activity.
Larger fish were generally more sensitive to supersaturation
than were smaller fish in most studies (Wiebe and McGavock
1932,142  Egusa  1955,114  Shirahata 1966,13C Harvey  and
Cooper 1962).123 Wood (1968)143 has the opposite view, but
he provides no supporting evidence. Possibly larger fish are
more susceptible to gas bubble disease in  part because they
can develop  greater metabolic heat than smaller fish. In
this regard, Carey and Teal (1969)108 reported that  large
tuna may have a muscle temperature as much as 10 C above
the water temperature.
  Data are quite  limited on  the tolerance of zooplankters
and other aquatic invertebrates to excessive dissolved gas
pressure. Evans and Walder (1969)116 demonstrated  that
invertebrates can develop gas bubble disease. Unpublished
observations by Nebekcr* demonstrate that Daphnia sp. and
Gammams sp. are susceptible to gas bubble disease. On the
other hand, it is widely known that some aquatic inverte-
brates are capable of dicl migrations that may expose them
to  a  considerable  change  in  dissolved  gas pressure; but
apparently these organisms can tolerate or otherwise handle
such changes. In view of the paucity of data, nothing firm
can be said regarding the general tolerance of invertebrates
to supersaturation.
Analytical Considerations
  The apparatus and method of Van Slyke et al. (1934)1
are still the standard analytical tools for most gas analyse
Scholander et al. (1955)134 and others have developed simih
methods with  modifications  to accomodate their speci;
needs. More recently, Swinrierton el al. (1962)137 publishe
a gas analysis  method  that utilizes gas-liquid  chromatoi
raphy. However, both  of these basic methods  have drav
backs, because  they either require special expertise or do n<
otherwise meet the field needs of limnologists and fisherl
or pollution biologists.
  A new device by  Weiss* measures the differential  g;
pressure between the  air  and the  water within  fiftee
minutes. This portable device is simple to operate, easy an
inexpensive to  build, and gives direct readings in mm Hi
Unpublished data by Weiss show that this instrument h;
an  accuracy comparable to the Van Slyke and the chn
matographic procedures. The instrument consists of a g;
sensor (150 ft.  coil of small diameter,  thin-walled, silicor
rubber tube)  connected to a  mercury  manometer.  Tt
sensor is placed  underwater where the  air  in  the  tubir
equilibrates  with the dissolved gases in  the  water.  Tt
resulting  gas  pressure  is  read  directly  via the  mercui
manometer which gives a positive value for supersaturate
water and a  negative value  for water that  is not  ful

Total Dissolved Gas Pressure Criteria
  Safe upper limits for dissolved gases must be based on tt
total dissolved  gas pressures (sum of all gas tensions) an
not solely on the saturation value of dissolved nitrogen g:
alone. Furthermore, such limits must provide for the safei
of aquatic organisms that  inhabit or frequent the shallo
littoral zone, where  an existing supersaturation could 1
worsened  by heating,  photosynthetic oxygen  productio
or other factors.  There is little information on the chron
sublethal effects  of gas  bubble disease and  almost  all tl
research has been limited to species of the family Salmonida
Likewise, gas tolerance data are unavailable for zooplankte
and most other aquatic invertebrates. Therefore, it is nece
sary to judge safe limits from data  on mortality of selects
salmonid fishes that were  held  under conditions appros
mating the shallow water  of a  hypothetical littoral zon
These data are:

   1.   Shirahata  (1966)136  reported that advanced fry <
rainbow trout (Salmo  gairdneri) experienced 10 per  cei
mortality when N2 was about 111 per cent of its saturatic
value. He  concludes that, ". . .  the nitrogen contents whic
did  not  cause  any gas disease were . . . less than 110 pi
cent to the more advanced fry."
  * A. V. Nebeker, Western Fish Toxicology Station, U.S. Environ-
mental Protection Agency, 200 S. W. 35th Street, Corvallis, Oregon,
  * Dr.  Ray Weiss, University  of California, Scripps.  Institute
Oceanography, Geological Research Division, P. O. Box 109, Lajoll
California 92037.

                                                                                             Dissolved Gases/139
  2.  Harvey and  Cooper (1962)123 reported that  fry of
sockeye salmon  (Oncorhynchus nerka) suffered latent  effects
(necrosis and hemorrhages) for some time after normal gas
levels were said to have been restored.
  3.  Coutant and  Genoway (1968)109 reported that sexu-
ally precocious spring chinook salmon (Oncorhynchus tshawyt-
scha) weighing 2  to 4 kg, experienced extensive mortality
in six days when exposed at or above 118  per  cent of N2
saturation; these salmon experienced no mortality when
Ns  was below 110 per cent of saturation.

  Whether or not other species or life  stages of aquatic life
may be more or less sensitive than the above salmonids
remains to be proven.  In the meantime, the above refer-
ences provide the main basis for establishing the following
total dissolved gas recommendations.


  Available  data for  salmonid fish  suggest that
aquatic life will be protected only  when  total dis-
solved gas pressure in water is no greater than 110
per cent of  the existing atmospheric pressure. Any
prolonged artificial increase in total dissolved gas
pressure should be avoided in view of the incom-
plete body of information.


  Carbon dioxide exists  in two  major forms in water. It
may enter into the bicarbonate buffering system at various
concentrations depending on the pH of the water. In ad-
dition, "free" carbon dioxide may also exist, and this com-
ponent affects the respiration offish (Fry 1957).151 Because
of respiratory effects, free carbon dioxide is the form con-
sidered most significant to aquatic life.
  The concentration of free carbon dioxide, where oxygen-
demanding wastes are  not  excessive, is  a function of pH,
temperature,  alkalinity, and the atmospheric pressure of
carbon dioxide. Doudoroff  (1957)147 reported that concen-
trations of free carbon dioxide above 20 mg/1 occur rarely,
even in polluted waters; and Ellis (1937)150 found that the
free carbon dioxide content of Atlantic Coast streams ranged
between zero and 12 mg/1. Ellis (1937)160  and Hart (1944)162
both reported that in 90  to 95  per cent of the fresh waters
in the United States that support a good and diverse fish
population the free carbon dioxide concentrations fall below
5 mg/1.
  An excess of free carbon dioxide may have adverse effects
on  aquatic life.  Powers and Clark  (1943)166 and Warren
(1971)167 reported that fish are able to detect and to respond
to slight  gradients  in  carbon  dioxide  tension.  Brinley
(1943)146 and Hoglund (1961)184 observed that fish may
avoid free carbon dioxide levels as low as  1.0 to 6.0 mg/1.
  Elevated carbon dioxide concentrations may interfere
with the ability of fish  to respire properly and  may thus
affect  dissolved  oxygen  uptake.  Doudoroff  and  Katz
(1950)148 and Doudoroff and Shumway (1970)149 reported
that where dissolved oxygen uptake interference does occur,
the free carbon  dioxide concentrations which appreciably
affect this are higher than those found in  polluted  waters.
In bioassay tests using ten species of warmwater  fish, Hart
(1944)152 found that the gizzard shad (Dorosoma cepedianum)
was the most sensitive  and was unable to remove  oxygen
from water 50 per cent  saturated with dissolved oxygen in
the presence  of 88 mg/1 of free carbon dioxide. The less
sensitive, largemouth bass (Micropterus salmoides) was unable
to extract oxygen  when the carbon dioxide level reached
175 mg/1.  Below  60 mg/1  of free  carbon dioxide,  most
species of fish  had little  trouble in extracting dissolved
oxygen from the water.
  High concentrations  of free carbon  dioxide cause pro-
nounced increases in the  minimum dissolved oxygen require-
ment  of coho salmon (Oncorhynchus kisutch), but  these fish
acclimatized  rapidly to carbon dioxide concentrations as
high as  175 mg/1 at 20  C when the  dissolved oxygen level
was near saturation (McNeil 1956).155
  Basu  (1959)146 found  that for most fish species,  carbon
dioxide affected the fishes' ability to consume oxygen in a
predictable manner. He further indicated that temperature
affected carbon dioxide sensitivity, being less at higher water
  The ability of fish to  acclimatize  to increases in  carbon
dioxide concentrations as high as 60 mg/1  with little effect
has been indicated by  Haskell and  Davies   (1958).153
Doudoroff and Shumway (1970)149 indicate that  the ability
of fish to detect low free carbon dioxide concentrations, the
presence of low  carbon  dioxide levels in most waters, and
the ability of fish to acclimatize to  carbon dioxide in the
water probably prevent this constituent  from   becoming
a major hazard.

  Concentrations of  free carbon dioxide  above  20
mg/1 occur  rarely. Fish acclimatize to increases in
carbon dioxide levels as high as 60 mg/1 with little
effect. However, fish are able to  detect and respond
to slight  gradients  and many avoid free carbon
dioxide levels as low as 1.0 to 6.0 mg/1.

                                    ACIDITY,  ALKALINITY, AND  pH
  Acidity in natural waters is caused by carbon dioxide,
mineral acids,  weakly dissociated acids, and the salts of
strong acids and  weak bases.  The alkalinity of a water is
actually  a  measure of  the  capacity of  the  carbonate-
bicarbonate system to  buffer the water against change in
pH. Technical  information on alkalinity has recently been
reviewed by Kemp (1971).162
  An  index of the hydrogen ion activity  is pH. Even
though pH determinations  are used as an  indication of
acidity or alkalinity or both, pH is not a measure  of either.
There is a relationship between pH, acidity, and alkalinity
(Standard  Methods 1971):164  water with a  pH of 4.5 or
lower has no measurable  alkalinity, and water with a pH
of 8.3 or higher has  no measurable  acidity.  In natural
water, where the pH may often  be in the vicinity of 8.3,
acidity is not a factor of concern. In most productive fresh
waters, the pH  falls in a range between 6.5  and 8.5 (except
when increased by photosynthetic activity).  Some  regions
have soft waters with poor buffering capacity and  naturally
low pH.  They  tend to be less productive. Such conditions
are found especially in dark colored waters draining from
coniferous  forests or muskegs, and in swampy sections of
the Southeast.  For a variety of reasons, some waters may
exhibit quite extreme pH values. Before these are considered
natural conditions,  it should be ascertained that they have
not actually resulted  from man-made changes,  such as
stripping of ground cover or old mining activities.  This is
important because the  recommendations refer to estimated
natural levels.

  Some  aquatic  organisms,  especially algae,  have  been
found to live at pH 2 and lower, and others  at pH 10 and
higher; however, such organisms are relatively few. Some
natural waters  with a pH of 4 support healthy populations
of fish and other organisms. In  these cases  the acidity is
due primarily to carbon dioxide and natural organic acids,
and  the water  has little  buffering capacity. Other  natural
waters with a pH of 9.5 also support fish but are not usually
highly productive.
  The effects of pH on aquatic life have been reviewed i
detail in excellent reports by the European Inland Fisherii
Advisory  Commission (1969)160 and Katz (1969).161 Ii
terpretations and summaries of these reviews are given i
Table 111-6.


  Addition  of  either acids or alkalies to water  may I
harmful not only by producing acid or alkaline condition
but also  by increasing the toxicity of various componeri
in the waters.  For  example, acidification  of  water ma
release free carbon dioxide. This exerts a toxic  action ac
ditional to that of the lower prl. Recommendations for p]
are valid  if carbon  dioxide is less  than 25 mg/1  (see tt
discussion of Carbon Dioxide, p. 139).
  A reduction of about 1.5 pH units can cause a thousanc
fold  increase in  the acute  toxicity of a metallocyanic
complex  (Doudoroff et al.  1966).169 The addition of stron
alkalies may cause the formal ion of undissociated NH4OH c
un-ionized NH3 in quantities that  may be toxic  (Lloy
1961,163  Burrows  1964).158 Many   other pollutants ma
change their toxicity to a lesser extent. It is difficult 1
predict whether  toxicity  will increase or decrease  for
given direction of change in pH.
  Weakly dissociated acids and bases must be  considere
in terms of their toxicities, as well  as their effects on pi
and alkalinity.
  The availability of many nutrient substances varies wit
the hydrogen ion concentration. Some trace metals becon'
more soluble at low pH. At higher pH values, iron tenc
to become unavailable to some plants, and hence the prc
duction of the whole aquatic community may be affectec
  The major buffering system in  natural waters  is th
carbonate system that not  only neutralizes acids and base
to reduce the fluctuations in  pH, but also forms a reserve
of carbon for photosynthesis. This process is indispensabl(
because there is a limit on the rate at which carbon dioxid
can be obtained from the atmosphere to replace that in th
water. Thus the productivity of waters is closely correlate
to the carbonate buffering system. The addition of miners
acids preempts the carbonate buffering capacity, and th

                                                                                                      Acidity, Alkalinity, and pH/\4\
     TABLE III-6—A Summary of Some Effects of pH on
        Freshwater Fish and Other Aquatic Organisms
11 5-12.0
11 0-11 5
10 5-11.0
5.5-6 0
                                  Known effects
 Some caddis flies (Trichoptera) survive but emergence reduced.
 Rapidly lethal to all species of fish.
 Rapidly lethal to salmonlds. The upper limit is lethal to carp (Cyprinus carpio), goldfish (Carassius
  auratus), and pike. Lethal to some stoneflies (Plecoptera) and dragonflies (Odonata). Caddis
  fly emergence reduced.
 Withstood by salmomds for short periods but eventually lethal. Exceeds tolerance of bluegills
 (Lepomis macrochirus) and probably goldfish- Some typical stoneflies and mayflies (Ephemera)
  survive with reduced emergence.
 Lethal to salmomds over a prolonged period of time and no viable fishery for coldwater species.
  Reduces populations of warmwater fish and may be harmful to development stages. Causes
  reduced emergence of some stoneflies.
 Likely to be harmful to salmomds and perch (Perca) if present for a considerable length of time
  and no viable fishery for coldwater species. Reduced populations of warmwater fish. Carp avoid
  these levels.
 Approaches tolerance limit of some salmonids,  whitefish (Coregonus), catfish (Ictaluridae), and
  perch. Avoided by goldfish. No  apparent effects on invertebrates.
 Motihty of carp sperm reduced. Partial mortality of burbot (Lota lota) eggs.
Full fish production. No known harmful effects on adult or immature fish, but 7.0 is near low limit
  for Gammarus reproduction and perhaps for some other crustaceans.
 Not lethal to fish unless heavy metals or cyanides that are more toxic at low pH are present.
  Generally full fish production,  but for fathead minnow (Pimephales promelas), frequency of
  spawning and number of eggs are somewhat reduced. Invertebrates except crustaceans relatively
  normal, including common occurrence of mollusks Microorganisms, algae, and higher plants
  essentially normal.
 Unlikely to be toxic to fish unless free carbon dioxide is presentin excess of 100 ppm. Good aquatic
  populations with varied species can exist with some exceptions. Reproduction of Gammarus and
  Daphma prevented, perhaps other crustaceans. Aquatic plants and microorganisms relatively
  normal except fungi frequent.
 Eastern brook trout (Salvelinus fontmalis) survive at over pH 5.5. Rainbow trout (Salmo gairdneri)
  do not occur. In natural situations, small populations of relatively (ew species of fish can be
  found. Growth rate of carp reduced. Spawning of fathead minnow significantly reduced. Mollusks
 Very restricted fish populations but not lethal to any fish species unless CO: is high (over 25 ppm),
  or water contains iron salts. May be lethal to eggs and larvae of sensitive fish species. Prevents
  spawning of fathead minnow. Benthic invertebrates moderately diverse, with certain black flies
  (Simuliidae), mayflies(Ephemerella), stoneflies,and midges (Chironomidae) presentin numbers.
  Lethal to other invertebrates such as the mayfly. Bacterial species diversity decreased; yeasts
  and sulfur and iron bacteria (Thiobacillus-Ferrobacillus) common. Algae reasonably diverse and
  higher plants will grow.
 No viable fishery can be maintained. Likely to be lethal to eggs and fry of salmomds. A salmomd
  population could not reproduce. Harmful, but not necessarily lethal to carp. Adult brown trout
  (Salmo trutta) can survive in peat waters. Benthic fauna restricted, mayflies reduced. Lethal to
  several typical stoneflies. Inhibits emergence of certain caddis fly, stonefly, and midge larvae.
  Diatoms are dominant algae.
 Fish populations limited; only a few species survive. Perch, some coarse fish, and pike can accli-
  mate to this pH, but only pike reproduce. Lethal to fathead minnow. Some caddis flies and dragon-
  flies found in such habitats; certain midges dominant. Flora restricted.
 Lethal to silmonids and bluegills. Limit of tolerance of pumkinseed (Lepomis gibbosus), perch,
  pike, and some coarse fish. All flora and fauna severely restricted in number of species. Cattail
  (Typha) is only common higher plant
 Unlikely that any fish can survive  for more than a few hours. A few kinds of invertebrates such as
  certain midges and alderflies, and a few species of algae may be found at this pH range and lower
original biological productivity is reduced in proportion to
the  degree that such capacity  is exhausted.  Therefore,  the
minimum  essential  buffering  capacity and tolerable   pH
limits are  important water quality considerations.
   Because of this importance,  there should be  no serious
depletion  of the carbonate  buffering  capacity,  and it is
recommended  that reduction of alkalinity of natural waters
should  not exceed 25 per cent.
   Suggested  maximum  and  minimum  levels  of
protection for aquatic life are given in the following
recommendations. A  single range of  values  could
not apply to all kinds  of fish, nor could it cover the
different degrees of graded effects. The selection of
the level of protection is a socioeconomic decision,
not a biological one.  The levels are denned in  Table
III-3 (see the discussion of Dissolved Oxygen).

Nearly  Maximum Level of Protection
     • pH not less than  6.5 nor  more  than 8.5. No
        change greater than 0.5 units above the esti-
        mated  natural  seasonal maximum, nor be-
        low  the  estimated  natural  seasonal  mini-

High  Level of Protection
     • pH not less than  6.0 nor  more  than 9.0. No
        change greater   than  0.5  units outside the
        estimated natural  seasonal  maximum  and

Moderate Level of Protection
     • pH not less than  6.0 nor  more  than 9.0. No
        change greater   than  1.0  units outside the
        estimated natural  seasonal  maximum  and

Low Level of  Protection
     • pH not less than  5.5 nor  more  than 9.5. No
        change greater   than  1.5  units outside the
        estimated natural  seasonal  maximum  and

Additional Requirements for All Levels of Protection
     • If a natural pH is outside the stated range of
        pH for a  given level of protection, no further
        change is desirable.
     • The extreme range of pH  fluctuation in any
        location should  not be greater than 2.0 units.
        If natural fluctuation exceeds this, pH should
        not be altered.
     • The natural daily and  seasonal patterns  of
        pH variation should be maintained, although
        the absolute values may  be altered  within
        the limits specified.
     • The total alkalinity of water is not to be de-
        creased  more  than 25  per  cent  below  the
        natural level.

                                 DISSOLVED  SOLIDS  AND  HARDNESS
  Surface water at  some time  and place may contain  a
trace or more of any water-soluble substance. The signifi-
cance and the effects of small concentrations of these sub-
stances  are  discussed separately throughout this Report.
The presence and relative abundance  of these constituents
in water is influenced by several factors, including surface
runoff, geochemistry of the  watershed, atmospheric fallout
including snow  and  rainfall, man-created  effluents, and
biological and chemical processes in the water itself. Many
of these dissolved materials are essential to the life processes
of aquatic organisms. For a  general discussion of the chem-
istry of fresh water  the reader is referred  to Hutchinsori
(1957)167 and Ruttner (1963).172
  A general term describing the concentration of dissolved
materials in water is total dissolved solids.  The more con-
spicuous constituents of total  dissolved solids in natural
surface waters include carbonates, sulfates, chlorides,  phos-
phates,  and nitrates. These anions  occur in combination
with such metallic cations as calcium, sodium, potassium,
magnesium, and iron to form ionizable salts (Reid 1961).170
  Concentrations and relative proportions of dissolved ma-
terials  vary widely  with locality and time.  Hart   et al.
(1945)166 reported that  in the inland waters of the United
States which support a  mixed biota, 5 per cent have  a dis-
solved  solids concentration  under 72  mg/1; about 50 per
cent under  169 mg/1;  and 95  per  cent under 400  mg/1.
Table  III-7 provides information on ranges  and median
concentrations of the major ions in United States streams.
  The quantity and  quality of dissolved solids are  major
factors in determining the variety and  abundance of  plants
and animals in  an aquatic system. They serve as nutrients
in productivity,  osmotic stress, and direct toxicity. A  major
change in quantity or composition of  total dissolved solids
changes the structure and function  of aquatic ecosystems.
Such changes are difficult to predict.
  Concentrations of dissolved  solids  affecting freshwater
fish by  osmotic  stress are not well known.  Mace  (1953)169
and Rounsefell  and  Everhart  (1953)171 reported  that the
upper limit may range between 5,000 and 10,000 mg/1 total
dissolved solids, depending  on  species  and prior acclimati-
zation. The literature indicates  that concentrations of total
dissolved solids that cause osmotic stress in adult fish a:
higher than the concentrations existing in most fresh wate
of the United States. Many dissolved materials are toxic
concentrations lower  than those where osmotic  effect cz
be expected. (See Toxic Substances, p. 172, and  Acidit
Alkalinity, and pH, p. 140.)
  Hardness of surface waters is a component of total di
solved solids and is  chiefly attributable  to  calcium  ar
magnesium ions. Other ions such as  strontium,  bariur
manganese, iron, copper, zinc,  and lead add to hardnes
but since they are normally  present in minor concentratioi
their  effect is usually minimal.  Generally, the  biologic
productivity of a water is directly correlated with its han
ness. However, while  calcium and magnesium contribu
to hardness and productivity, many other elements (whc
present in concentrations  which  contribute  a substanti
measure of hardness)  reduce biological  productivity  ar
are toxic.  Hardness, per se has no  biological significani
because  biological  effects are  a  function of the specii
concentrations and combinations of the elements present
  The term "hardness" serves a useful purpose as a gener
index of water type, buffering capacity,  and productivit
Waters high in calcium and magnesium ions (hard wate
lower  the  toxicity of many metals to aquatic life (Brov
1968;166 Lloyd  and Herbert 1962).168 (See Figure  III-9
the  discussion  of Metals,  p.  178.)  However,   the  ter
"hardness" should be  avoided in delineating water quali
TABLE III-7—Major Dissolved Constituents of River Wate
Representing About 90 Percent of Total Stream Flow in tl
                      United States
                            Median mg/1
Range mg/1
Total dissolved solids
Bicarbonate (HCO,) .
Sulfate (SOO
Chloride (Cl)
Calcium (Ca)
Magnesium (Me)
Sodium and potassium (Na and K)
                                                           Source: Alter Hart etal.(1945)15«

                                                                          Dissolved Solids and Hardness/143
requirements for aquatic life. More emphasis  should be
placed on specific ions.


  Total dissolved materials should not be changed
to the  extent that the  biological communities
characteristic  of  particular  habitats are signifi-
cantly changed. When dissolved materials are al-
tered,  bioassays and field  studies can determine
the  limits  that  may  be  tolerated  without  en-
dangering  the structure  and  function of  the
aquatic ecosystem.

  Losses of oil that can have  an adverse effect on water
quality and aquatic life can occur in many of the phases of
oil production, refining, transportation, and use. Pollution
may be in the form of floating oils, emulsified oils, or solution
of the water soluble fraction of these oils.
  The toxicity of crude oil has been difficult to  interpret
since crude oil may contain many different organic com-
pounds  and inorganic elements.  The composition of such
oils may-vary from region to region, and petroleum products
produced can be drastically different in  character in line
with their different intended  uses  (Purdy 1958).198 The
major components of crude oil can be categorized as ali-
phatic normal hydrocarbons, cyclic paraffin hydrocarbons,
aromatic hydrocarbons, naphtheno-aromatic hydrocarbons,
resins, asphaltenes, heteroatomic compounds, and metallic
compounds  (Bestougeff  1967).m The  aromatic  hydro-
carbons in crude oil appear to be the major group of acutely
toxic compounds (Blumer  1971,176 Shelton  1971).199
  Because the biological effects  of oils  and  the relative
merits of  control  measures  are discussed  in  detail  in
Section  IV (p. 257) of this Report, only effects of special
interest  or  pertinence  to fresh water are  discussed here.
The effects of floating oil on wildlife are discussed on p. 196.


  Copeland  and  Dorris (1964)180 studied  primary pro-
ductivity  and  community  respiration in  a series  of  oil
refinery  effluent  oxidation ponds. These  ponds received
waste waters which had been in contact with the crude oil
and various products produced within the refinery. Surface
oils were  skimmed. In the series of oxidation ponds, pri-
mary productivity and community  respiration  measure-
ments clearly indicated that primary producers were limited
in the first ponds, probably by toxins in the water. Oxidation
ponds further along in the series  typically supported algal
blooms. Apparently degradation of the toxic organic com-
pounds reduced  their  concentration below the threshold
lethal to  the algae. Primary productivity was not greater
than community respiration in the first ponds in the series.
Minter  (1964)195  found  that  species diversity  of phyto-
plankton was lowest in the first four ponds of the series
ten.  A "slug" of unknown toxic  substance  drastically r
duced  the  species diversity  in  all ponds.  Zooplanktc
volumes  increased  in  the latter  half of the  pond serie
presumably as a result of decreasing toxicity. Benthic faur
species diversity in streams receiving oil refinery effluen
was low near the outfall and progressively increased dowi
stream as biological assimilation reduced the concentratk
of toxins (Wilhm and  Dorris  1966,206 Harrel et al. 1967,-
Mathis and Dorris  1968191).
   Long-term,  continuous-flow bioassays  of biological
treated oil  refinery effluents  indicated  that  complex r
fineries produce effluents which contain  cumulative toxii
of substances that cause  accumulative deleterious eff'ec
(Graham and Dorris  1968).182 Subsequent long-term coi
tinuous-flow bioassays of biologically  treated oil  refine]
effluents indicated that passage of the effluent through ad
vated carbon columns does not remove  the fish toxicant
Of the fathead minnows (Pimphales promelas) tested,  hi
were killed in  14 days, and only 10 per cent survived '
days (Burks 1972207 personal communication).  Trace organ
compounds identified  in extracts  from the effluent were
homologous series of aliphatic hydrocarbons (CnH22 throm
CisHas) and isomers of cresol and  xylenol. Since the solub
fractions derived from oil refineries are quantitatively, ar
to some  extent  qualitatively, different from those derive
from oil  spills, care must be taken to differentiate betwec
these two sources.

   Free oil or emulsions may adhere  to  the gills  of fis
interfering with respiration and causing asphyxia.  Withi
limits, fish are able  to  combat this by defensive mucoi
secretions  (Cole 1941 ).179 Free oil and  emulsions may liki
wise coat  aquatic  plants and destroy them (McKee an
Wolf 1963).193
   Fish and benthic organisms may be  affected  by solub
substances extracted  from the  oils or by  coating  froi
emulsified oils. Water soluble  compounds from crude c

manufactured  oils may  also contain  tainting substances
which affect the taste of fish and waterfowl  (Krishnawami
and Kupchanko 1969).189
  Toxicity tests for oily substances provide  a broad range
of results which do not permit rigorous safety evaluations.
The variabilities are due  to differences in petroleum prod-
ucts tested,  non-uniform  testing  procedures,  and  species
differences.  Most of the research  on the effects of oils  on
aquatic life has used pure compounds which exist only in
low percentages in many  petroleum products or crude oils.
Table 111-8 illustrates the range of reported toxicities. For
halo-, nitro-,  or  thio-derivatives, the  expected  toxicity
would be greater.
  Because of the basic difficulties in evaluating the toxicity,
especially of the emulsified oils, and  because there is  some
evidence  that  oils may persist  and have subtle chronic
effects (Blumer 1971),m> the maximum allowable concen-
tration of emulsified oils should be determined on an  indi-
vidual basis and kept below 0.05 of the 96-hour LC50 for
sensitive  species.
                                           TABLE III-8—Toxicity Ranges

Cyclohnane ..


Heptane . . .
Isopreae ...


NffMnJim ...


Brtlint oil 2
Binkaroil .
Blinker C oil . .
ppm. cone.
E fleet
96 hr LC50
96 hr LC50
96 hr LC50
96 hr LC50
96 hr LC50
96 hr LC50
" . .

" . .
". .
" . .

48 hr LC50
96 hr LC50
" . .
". .
". .
" . .
48 hr LC50
". .
96 hr LC50
" . .
" . .
48 hr LC50
96 hr LC50
96 hr LC50
48 hr LC50
. .". .
168 hr LC50
Daphma magna
Pimeptiaies promelas
Lepomis macrochirus
Carassius auratus
Lepomis macrochirus
Pi mephales promelas
Lepomis macrochirus
Carassius auratus
Lebistes reticulatus
. Pimephales promelas
Lepomis macrochirus
. Carassius auratus
. Lebistes reticulatus
Gambusia affims
Pimephales promelas
. Lepomis macrochirus
Carassius auratus
Lebistes reticulatus
Lepomis macrochirus
Physa heterostropha
Gambusia aflinis

Pimephales promelas
. Lepomis macrochirus
Carassius auratus
Lebistes reticulatus
Alosa sapidissima
Salmo gairdnen
Salmo gairdnen
Alosa sapidissimia
. Alosa sapidissima
Salmo salar
Anderson 194417"
Pickering & Henderson 19661"
" . . ".
" ".
Cairns & Scheier 1959'-
Pickering & Henderson 19661"
" . ".
" ". ....
". ...
" ". .......

". . . .
Wallen et al. 1957™'
Pickering & Henderson 1966""

" . ".
Cairns & Scheier 1958"'
" ". . .. .
Wallen etal !957Mi

Pickering & Henderson 19661"
" ".
" " 	

Meincketal. 19561"
Turnbulletal 1954-"'
Tagatz 19612"M

Sprague and Carson manuscript 1970MO

  Ludzack et al. (1957)190 found that the sediment in the
Ottawa River in Ohio downstream from a refinery consisted
of up to 17.8 per cent oil. Hunt (1957)187 and Hartung and
Klingler (1968)185 reported on the occurrence of sedimented
oil in the  Detroit River. North et al. (1965)196 found  sedi-
mented oils after an oil pollution incident in marine coves
in Baja California.  Forbes and Richardson (1913)181 re-
ported 2.5 per cent oils in the bottom deposits of the Illinois
River. McCauley (1964)192 reported finding oily bottom
deposits after oil pollution near Boston. Thus,  while the
reports may be  scattered, the  evidence  is clear that the
existence of sedimented oils in association with oil pollution
is widespread.
  There is an increasing body of evidence indicating that
aliphatic hydrocarbons are synthesized by aquatic organisms
and find their way into sediments in areas which have little
or no history of oil  pollution (Han et  al. 1968,'83 Avigan
and Blumer 1968174). Hydrocarbons have been reported in
the recent sediments of lakes in  Minnesota (Swain  1956)202
and the Gulf of Mexico (Stevens et al. 1956).201
  Areas which contain oily sediments usually have an im-
poverished benthic fauna; it is not clear to what extent oil
contributes to  this, because  of the presence of other pol-
lutants (Hunt 1962).188 However, there are recurring reports

146/Section HI—Freshwater Aquatic Life and Wildlife
of a probable relationship between sedimented oils and
altered benthic communities. Sedimented oils may act as
concentrators for chlorinated hydrocarbon pesticides  (Har-
tung and Klingler 1970),186 but the  biological implications
indicate that additional study is required.
  Because of the differences in toxicities of sedimented oils
and because of limited knowledge on quantities which are
harmful to aquatic life, it is suggested that the concentration
of hexane extractable substances (exclusive of elemental
sulfur) in air-dried sediments not be permitted to increase
above 1,000 mg/kg on a dry weight basis.

  Aquatic  life  and  wildlife  should be  protected
• there is no visible oil on the surface;
• emulsified oils do not exceed 0.05 of the 96-hour
» concentration of hexane extractable substances
  (exclusive of elemental sulfur) in air-dried sedi-
  ments does not increase above 1,000 mg/kg on a
  dry weight basis.

                                         TAINTING  SUBSTANCES
  Discharges from municipal wastewater treatment plants,
a variety of industrial wastes and organic compounds, as
well as biological organisms, can impart objectionable taste,
odor,  or color to the flesh of fish  and other edible aquatic
organisms.  Such tainting can occur in waters with concen-
trations of  the offending material lower than those recog-
nized  as being harmful  to an animal (Tables III-9 and


  Thaysen  (1935)231 and Thaysen and Pentelow (1936)232
demonstrated that a muddy or earthy taste can be imparted
to the flesh of trout by material produced by an odiferous
species of Actinomyces. Lopinot (1962)224  reported a serious
fish and municipal  water supply  tainting problem on the
Mississippi  River in  Illinois during a period  when actino-
mycetes, Oscillatoria, Scenedesmus, and Actinastrum were abun-
dant.  Oscillatoria princeps and  0.  agardhi in plankton  of a
German lake were  reported by Cornelius   and  Bandt
(1933)213 as causing  off-flavor in  lake fish. Aschner et  al.
(1967)210 concluded  that the benthic alga,  O. tenms,  in
rearing  ponds in Israel was responsible for imparting  such
a bad flavor to carp  (Cyprinus carpw) that the fish were
unacceptable on the market. Henley's (1970)221 investigation
of odorous metabolites of Cyanophyta showed  that Anabaena
circinahs releases geosmin and indicated that  this material
was responsible for the musty or earthy odor often  char-
acteristic of water from reservoirs  with heavy  algal  growths
in summer  and fall.
  Oysters occasionally exhibit green coloration of the gills
due to absorption of the blue-green pigment of the diatom,
Navicula, (Ranson 1927).226


  Phenolic compounds are often associated with both water
and fish tainting problems (Table  III-9). However, Albers-
meyer (1957)208 and Albersmeyer and  Erichsen (1959)209
found that, after being dephenolated, both a carbolated oil
and a light  oil still imparted a taste to fish more pronounced
than  that produced by similar exposures  to naphthalene
and  methylnaphthalene (phenolated  compounds).  They
concluded that other hydrocarbons in the oils were more
responsible for imparting off-flavor than the phenolic ma-
terials in the two naphthalenes tested.
  Refineries (Fetterolf 1962),216 oily wastes (Zillich 1969),236
and crude oil (Galtsoff et al. 1935)219 have been associated
with ofT-flavor problems of fish and shellfish in both fresh-
water and marine  situations (Westman and Hoff 1963).234
Krishnawami and  Kupchanko (1969)223 demonstrated that
rainbow trout (Salmo gairdneri) adsorbed enough compounds
from  a  stream  polluted with oil slicks and  oil refinery
effluents to exhibit  a definite oily taste and flavor. In waters
receiving black liquor from kraft pulp  mills, the  gills and
mantles of oysters  developed a gray color (Galtsoff et al.
1947).218 The authors also found this condition in oysters
grown  in  waters   receiving domestic  sewage.  Newton
(1967)237 confined  trout in live-cages and correlated inten-
  TABLE 111-9—Wastewaters Found to have Lowered the
                Portability of Fish Flesh
Wastewater source
2, 4-D mf(. plant
Coal— coking
Kraft process (untreated)

Kraft process (treated)

Kraft and neutral sulfite
Municipal dump runoff

Municipal untreated sewage
(2 locations)
Municipal wastewater
treatment plants (4 locations)
Municipal wastewater
treatment plant (Primary)
Municipal wastewater
treatment plant (Secondary)
Oily wastes
Sewage containing phenols
Slaughterhouses (2 locations)
Concentration in
water affecting
payability of fish
50-100 mg/l
0.02-0.1 rroj/l
1-2% by vol.

9-12% by vol.

11-13% hy »ol.

20-26% oy vol.

O.lmg 1

Freshwater fish
Freshwater fish



Channel catfish
(Ictalurus punctatus)
Channel catfish

Channel catfish

Freshwater fish

Freshwater fish

Freshwater fish
Channel catfish
Shumway 1956««
Bandt 1955'-"
Bandt 1955="
Shumway and Chadwick
Shumway and Palensky, un-
published data1"
Newton 1967":

Thomas and Hicks 19712"

Tnomas and Hicks 1971MJ

Thomas and Hicks 197V"

Shumway and PalensKy, un-
published data'"
Shumway and Palensky, un-
published data"8
Zilhch 1969»t
Fetterolf 1962""
Bandt 1955="
Thomas and Hicks 1971="

 \48/Section III—Freshwater Aquatic Life and Wildlife
 TABLE HI-10—Concentrations of Chemical Compounds in
 Water That  Can Cause Tainting of the Flesh of Fish and
                 Other Aquatic Organisms
                           Estimated threshold level in water
cresylic acid (meta para)
o-sec. butylphenol
p-ttrt. butylphenol
2-methyl, 4-chlorophenol
2-methyl, 6-chlorophenol
phenols in polluted river
riiphenyl oxide
(3,/3-dichlorodiethyl ether
kerosene plus kaolin
oil, emulsifiable
outboard motor fuel, as exhaust
0 12
0.0001 to 0.015
0.01 to 0.05
0 084
0 001 to 0 014
0 023
0 075
0 003
Ho tO
0.02 to 0.15
0.09 to 1.0
0 25
<0 25
0 25
5 to 28
0 8 to 5
20 to 30
0 5to1
2 S jal acre-foot

b,d, e
d, f, j

                                                                                            Tainting Sub stances /149
Boetius (1954)212 reported that eels required up to 11 days
exposure before flavor impairment was detected. The time
required to impair flavor was found to be related  to  the
exposure concentration, with low concentrations requiring
longer exposure periods.
  Shumway (1966)228 found that the flesh of salmon exposed
experimentally to industrial wastes containing mainly phe-
nols acquired  maximum off-flavor in 35 hours or less, with
much  of the  tainting occurring within the first 6  hours.
After the salmon were transferred to uncontaminated water,
most of the acquired  off-flavor was lost within  20  hours,
although some off-flavor remained up  to 72 hours.
  In other tests, Shumway and Palensky (unpublished data)™
observed flavor impairment in trout after 24-hour exposure
to 2,4-dichlorophenol. After only 33.5  hours in uncontami-
nated  water,  the flavor of the  trout had  returned  to  the
preexposure level, with most of the reduction in off-flavor
occurring within 6.5 hours.
  Korschgen  et  al.  (1970)222 transferred  carp (Cyprinus
carpio)  to uncontaminated ponds from two sites,  one  of
which  received effluents from a major municipality and one
of which received little or no  effluent. Retention up to  18
days in the holding ponds failed to improve the flavor of the
carp from the contaminated  site.  These authors also  re-
ported that channel catfish (Ictalurus punctatus) transferred
from the  Ohio River  to control water lost about half of
their off-flavor in 7 days and nearly all of it in  21 days.


  Determination that a tainting problem exists, or identifi-
cation  of a taint-causing material, involves field or labora-
tory exposure periods and organoleptic tests. When properly
conducted, these tests are  reliable but  time-consuming.
Wright (1966)238 reported on the use of gas chromatography
in conjunction with organoleptic tests. The chromatographic
scans were compared with scans of industrial process waste
streams to identify the taint-producing wastes. Gas chro-
matographic  techniques are employed routinely in food
technology laboratories investigating flavor and odor prop-
erties (Rhoades and Millar 1965).226


  Field exposure tests  (bioassays)  are  used to determine
the existence or the magnitude  of a tainting problem in a
water body. Fish or other edible aquatic life are held for a
period of time in cages at selected locations in and around
a suspected problem area or waste discharge and eventually
evaluated  for  flavor.  Laboratory bioassays are normally
utilized to determine the tainting potential of wastes, waste
components, or specific chemicals. Although either static
or continuous-flow bioassays can be used in laboratory tests,
continuous-flow systems are considered far superior to static
tests. Exposure bioassays are followed by the organoleptic
evaluation of the flesh of the test organisms.
   In their studies of tainted organisms, investigators have
used a number of different bioassay  and flavor-evaluation
procedures, some of which have produced poorly defined
results. The following guidelines are based primarily on the
successful procedures  of Shumway and  Newton (personal
Test Fish
   The flesh of the  fish to be exposed should be mild and
consistent in flavor. For convenience in holding and taste
testing, fish weighing between  200 and 400  grams are de-
sir able,  although smaller or  larger fish  are acceptable.
Largemouth bass (Micropterus salmoides), yellow perch (Perca
flavescens),  channel catfish, bluegill  (Lepomis macrochirus),
trout, salmon flatfishes (Pleuronectiformes), and others have
proven to be acceptable test fish.

Exposure Period
   In general, test fish should be exposed for a  period  not
less  than 48 hours. Shorter or  longer exposures will be
advisable in some situations, although possible stress, disease,
and mortality resulting from longer  retention of test  fish
and maintenance of holding facilities may negate advantages
of long exposure.

Exposure Conditions
   The following conditions are  desirable  in  laboratory
   Dissolved oxygen  	near saturation
   Temperature	10-15  C for salmonids, and
                           20-25  C  for warmwater fish
   pH	6.0-8.0, or pH  of receiving
   Light	intensity held at a low level
   Water	uncontaminated, or quality
                           of the receiving water; never
                           distilled water

Preparation of Test Fish and Evaluation
   Exposed fish and control fish, either fresh or fresh-frozen
and subsequently thawed, are individually double-wrapped
in aluminum foil, placed in an oven  and cooked at about
375 F for 15 to 30 minutes, as size requires. Large fish may
be portioned for cooking. No seasoning of any  kind is
added. Portions of _the cooked  fish  may be placed in small
coded cups and served warm to the judges for flavor evalu-
ation. A  known "reference" may be provided to aid judges
in making comparisons.  A minimum of ten experienced
judges, each seated in  an isolation booth or similar area,
smell, taste,  and score each sample. This  method offers
tighter control of variables and conforms more to off-flavor
evaluations  conducted in food  laboratories than the more
informal procedure below.

150/Section HI—Freshwater Aquatic Life and Wildlife
  An alternative method is to place the cooked fish, still
partially wrapped in foil to preserve the heat and flavor,
on a large table. The judges start concurrently and  work
their way  around the table,  recording aroma and flavor.
If a judge tastes more than six samples during a test, a
lessening of organoleptic acuity may occur.
  When investigating the potential of a substance to pro-
duce taint, a word-evaluation scale for intensity of off-flavor
ranging from no off-flavor to extreme off-flavor, has proven
successful  with trained,  experienced judges. Numerical
values from  0 to 6 are applied to the word scale for  deri-
vation of off-flavor indices and statistical evaluation.
  When using the above method, less experienced judges
tend to  over-react to  slight off-flavor.  For this reason, in
less formal tests evaluating the effect of a substance on the
palatability of the organism, an hedonic scale accompanied
by word-judgments describing  palatability is appropriate,
i.e., 0—excellent,  1—very good, 2—good, 3—fair, 4—just
acceptable, 5—not quite acceptable, 6—very poor, inedible,
and 7—extremely poor,  repulsive. Scores of the judges on
each sample are averaged to determine final numerical or
word-judgment values.
  To determine whether there are acceptability differences
between controls and test organisms, a triangle test may be
used in  which two samples are alike and one is different.
Judges are asked to select the like samples, to  indicate the
degree of difference, and to rate both the like and the odd
samples on a preference scale.

  The triangle test is particularly well adapted to statistical
analysis,  but the organoleptic  testing  necessary is  more
extensive than when hedonic scales are used.
  Application of the two-way analyses of  variance to
hedonic-scale data is an  acceptable test,  but professional
assistance  with statistical procedures is desirable. Reliance
on the word-judgment system is sufficient for general  infor-
mation purposes.

• To  prevent  tainting of  fish  and  other  edible
  aquatic organisms, it is recommended that sub-
  stances which cause tainting should not be pres-
  ent in water in concentrations that lower the
  acceptability of such organisms as determined
  by exposure bioassay and organoleptic tests.
• Values  in Tables III-9  and IH-10 are  recom-
  mended as guidelines in determining what con-
  centrations of  wastes  and  substances in water
  may cause tainting of  the flesh of fish or other
  aquatic organisms.

                                        HEAT  AND TEMPERATURE
  Living organisms do not respond to the quantity of heat
but to degrees of temperature or to temperature changes
caused by transfer of heat. The importance of temperature
to acquatic organisms is well known, and the composition
of aquatic communities depends largely on the temperature
characteristics of their environment. Organisms have upper
and lower thermal tolerance limits, optimum temperatures
for growth,  preferred temperatures  in thermal gradients,
and temperature limitations for migration, spawning,  and
egg  incubation. Temperature  also affects  the  physical
environment of the aquatic medium, (e.g., viscosity, degree
of ice  cover,  and  oxygen capacity. Therefore, the com-
position of aquatic  communities depends largely  on tem-
perature characteristics  of the  environment.  In  recent
years there  has been an accelerated demand for  cooling
waters for power stations  that release large quantities of
heat, causing,  or threatening to cause, either a warming of
rivers, lakes, and coastal waters, or a rapid cooling when the
artificial sources of heat are abruptly terminated. For these
reasons, the environmental consequences  of  temperature
changes must  be considered in assessments of water quality
requirements of aquatic organisms.
  The "natural" temperatures of surface  waters of the
United States  vary from 0 C to over 40 C as a function of
latitude, altitude, season,  time  of day,  duration  of flow,
depth, and  many other variables. The agents that affect
the natural temperature are so numerous that it is unlikely
that  two bodies  of water, even in the same latitude, would
have exactly the same thermal characteristics.  Moreover, a
single aquatic habitat  typically  does not have uniform or
consistent thermal  characteristics. Since all  aquatic or-
ganisms (with the exception of aquatic mammals  and  a
few large, fast-swirnming fish) have body temperatures  that
conform to the water temperature, these natural variations
create  conditions that are optimum  at times,  but  are
generally  above or  below  optima for  particular  physio-
logical, behavioral, and competitive functions of the species
  Because significant temperature changes may affect the
composition of  an  aquatic or  wildlife  community, an
induced change in  the thermal characteristics of an  eco-
system may be  detrimental. On the other hand,  altered
thermal characteristics may be beneficial,  as evidenced in
most  fish hatchery  practices and  at other aquacultural
facilities. (See the discussion of Aquaculture in Section IV.)
  The general difficulty in developing suitable criteria for
temperature (which  would limit the addition of heat) lies
in determining the deviation from "natural" temperature a
particular body  of water can experience without suffering
adverse effects  on its biota. Whatever  requirements are
suggested,  a  "natural"  seasonal  cycle  must be retained,
annual  spring and fall  changes  in  temperature must be
gradual,  and  large unnatural  day-to-day  fluctuations
should be avoided. In view of the many variables, it seems
obvious that no single  temperature  requirement can be
applied uniformly to continental or large regional  areas;
the requirements must  be closely related to each body of
water  and  to   its  particular  community of organisms,
especially the important species found in it. These should
include invertebrates, plankton, or other plant and animal
life that may be of importance  to food chains or otherwise
interact with species of direct interest to man. Since thermal
requirements of various  species differ, the  social choice of
the species to be protected allows for different "levels of
protection" among water bodies as suggested by  Doudoroff
and Shumway (1970)272  for  dissolved oxygen criteria. (See
Dissolved Oxygen, p.  131.) Although such decisions clearly
transcend the scientific judgments needed in establishing
thermal criteria for protecting selected species, biologists can
aid in making  them. Some measures useful in assigning
levels of importance  to species are:  (1) high yield  to com-
mercial or sport fisheries, (2) large biomass in the existing
ecosystem (if desirable),  (3)  important links in food chains
of other species  judged  important for other reasons,  and
(4)  "endangered" or unique status.  If  it is desirable to
attempt strict preservation  of an existing ecosystem,  the
most sensitive species or life stage may dictate the criteria
  Criteria  for making  recommendations  for water tem-
perature to protect desirable aquatic life cannot be simply a
maximum allowed change from  "natural  temperatures."
This is principally because a change of even one degree from

 152/Section HI—Freshwater Aquatic Life and Wildlife
an ambient  temperature has varying significance for an
organism, depending upon where the ambient level lies
within the tolerance range. In addition, historic tempera-
ture records or, alternatively, the existing ambient tempera-
ture prior to any thermal alterations by man are not always
reliable  indicators of  desirable  conditions  for  aquatic
populations. Multiple developments of water resources also
change water temperatures both  upward  (e.g., upstream
power plants or shallow reservoirs) and downward  (e.g.,
dcepwater releases from large reservoirs),  so that "ambient"
and  "natural" are exceedingly difficult to define at a given
point over periods of several years.
  Criteria for temperature should consider both the multiple
thermal requirements of aquatic species  and requirements
for balanced communities. The number of distance require-
ments and the necessary values for each require  periodic
reexamination as knowledge of thermal  effects on aquatic
species  and  communities  increases.  Currently  definable
requirements include:

     • maximum  sustained  temperatures  that  are  con-
       sistent with maintaining  desirable  levels  of pro-
     • maximum levels of  metabolic acclimation to warm
       temperatures that will permit return  to  ambient
       winter  temperatures  should  artificial   sources of
       heat cease;
     • temperature 1 imitations for survival of brief exposures
       to temperature extremes, both upper and lower;
     • restricted temperature ranges  for various stages of
       reproduction, including (for fish) gonad  growth and
       gamete maturation, spawning migration, release of
       gametes,  development of the  embryo,  commence-
       ment of independent  feeding (and other activities)
       by juveniles; and temperatures required for meta-
       morphosis,  emergence, and other  activities of lower
     • thermal limits for diverse compositions of species of
       aquatic communities, particularly where reduction
       in  diversity creates nuisance  growths  of certain
       organisms,  or  where  important food   sources or
       chains are altered;
     • thermal requirements  of downstream aquatic life
       where upstream warming of a cold-water source will
       adversely affect downstream temperature require-

   Thermal criteria must also be formulated with knowledge
of how man alters temperatures, the hydrodynamics of the
changes, and how the biota can reasonably be expected to
interact  with the  thermal  regimes  produced. It is not
sufficient, for example, to  define only the  thermal criteria
for sustained production of a species in open waters, because
large numbers of organisms may also be exposed to thermal
changes by  being pumped  through the  condensers and
mixing zone  of a power  plant.   Design  engineers  need
particularly to  know  the biological  limitations  to their
design options in such instances. Such considerations may
-eveal nonthermal  impacts of cooling processes that may
outweigh temperature effects, such as impingement of fish
upon intake  screens, mechanical  or chemical damage  to
zooplankton  in  condensers,  or effects of altered  current
patterns on bottom fauna in a d ischarge area. The environ-
mental situations of aquatic  organisms (e.g.,  where they
are,  when they  are there,  in what numbers) must also  be
understood. Thermal criteria for migratory species should
be applied to a certain area only when the species is actually
there.  Although thermal  effects  of  power  stations are
currently of  great  interest, other less dramatic  causes  of
temperature change including deforestation, stream chan-
nelization,  and  impoundment of flowing water  must  be


  Thermal criteria  necessary for1 the protection of species or
communities are discussed separately  below. The order of
presentation of the different criteria does not imply priority
for any one body of water. The descriptions define preferred
riethods and procedures for judging thermal requirements,
and  generally do  not  give numerical  values  (except  in
Appendix II-C). Specific  values for all limitations would
require a biological handbook that is far beyond the scope
of this Section.  The criteria may  seem complex, but they
represent an extensively developed framework of knowledge
about biological responses.  (A sample application  of these
criteria begins on page  166, Use of Temperature Criteria.)


  Some basic thermal response? of aquatic organisms will
be referred  to  repeatedly  and are  defined and reviewed
briefly here. Effects of heat  on  organisms  and  aquatic
communities have been reviewec' periodically (e.g., Bullock
1955,"9 Brett 1956;253 Fry 1947,276 1964,278  1967;279 Kinne
1970296). Some effects have been analyzed in the context of
tfiermal modification by power plants  (Parker and Krenkel
!959.sos Krenkel and Parker 1969;298 Cairns 1968;261 Clark
1969;263 and Coutant  1970c269). Bibliographic information
is available from Kennedy and Mihursky (1967),294 Raney
and  Menzel (1969),su and from annual  reviews published
by   the  Water  Pollution  Control  Federation  (Coutant
1968,265 1969,266 f970a,267 1971270).
  Each species (and often each distinct life-stage of a. species)
has  a characteristic tolerance range  of temperature as a
consequence of  acclimations  (Internal biochemical adjust-
ments) made while at previous holding temperature (Figure
I1I-2; Brett 1956253). Ordinarily., the ends of this range, or
the lethal thresholds, are defined by survival of 50 per cent
of a sample of individuals. Lethal thresholds typically  are
referred to  as "incipient lethal temperatures,"  and tem-
perature beyond these ranges would be considered "ex-

                                                                                          Heat and 7 emperature/\53
 treme."  The  tolerance range  is adjusted upward by  ac-
 climation to warmer water and downward to cooler water,
 although there is  a  limit  to  such accommodation.  The
 lower end of the range •usually  is at zero degrees centigrade
 (32 F) for species in temperate latitudes (somewhat less for
 saline waters),  while the  upper  end terminates in  an
 "ultimate incipient lethal temperature" (Fry et al. 1946281).
 This ultimate  threshold temperature represents the "break-
 ing point" between the highest temperatures to which an
 animal can be  acclimated and the lowest  of the extreme
 temperatures that will kill the  warm-acclimated organism.
 Any rate of temperature  change over a period of minutes
      Ultimate incipient lethal temperature
  3  10 -
                5         10        15        20

                   Acclimation temperature —Centigrade
       After Brett 1960 254
FIGURE IH-2—Upper and  lower  lethal temperatures for
young sockeye salmon (Oncorhynchus nerka) plotted to
show the zone of tolerance. Within this zone two other zones
are represented to illustrate (I) an area beyond which growth
would be poor to none-at-all under the influence of the loading
effect of metabolic demand, and (2) an area beyond which
temperature is likely to inhibit normal reproduction.
            Acclimation temperature
                                                                              100            1,000

                                                                            Time to 50% mortality— Minutes
                                                               After Brett 1952 252
                                                          FIGURE III-3—Median resistance times to  high tempera-
                                                          tures  among young  Chinook (Oncorhynchus tshawytscha)
                                                          acclimated to temperatures  indicated. Line A-B denotes
                                                          rising lethal threshold (incipient lethal temperatures) with
                                                          increasing acclimation temperature.  This rise  eventually
                                                          ceases  at the ultimate lethal threshold (ultimate  upper
                                                          incipient lethal temperature), line B-C.
to a few hours will not greatly affect the thermal tolerance
limits, since acclimation to changing temperatures requires
several days (Brett 1941).251
  At the temperatures above and below the incipient lethal
temperatures, survival depends not only on the temperature
but  also on the duration of exposure, with  mortality oc-
curring  more rapidly the farther the temperature is from
the threshold  (Figure III-3). (See Coutant 1970a267 and
1970b268 for further  discussion  based on both field and
laboratory studies.)  Thus, organisms  respond  to  extreme
high  and low  temperatures in  a manner similar to the
dosage-response pattern which  is  common  to toxicants,
Pharmaceuticals, and radiation  (Bliss 1937).249 Such tests
seldom extend bevond one week in duration.
  Specific criteria for prolonged exposure (1 week or longer)
must be defined for warm and for cold seasons. Additional
criteria for gradual temperature (and life cycle)  changes
during  reproduction  and  development periods are  dis-
cussed on pp.  162-165.

 154/Section III—Freshwater Aquatic Life and Wildlife

   Occupancy of  habitats by most  aquatic  organisms is
 often limited within the thermal tolerance range  to tem-
 peratures  somewhat below  the  ultimate  upper incipient
 lethal temperature.  This is the result of poor physiological
 performance at near lethal levels (e.g.,  growth, metabolic
 scope for  activities, appetite, food  conversion  efficiency),
 interspecies  competition,  disease, predation,  and  other
 subtle ecological factors (Fry 1951 ;277 Brett 1971256). This
 complex limitation is evidenced by restricted southern and
 altitudinal distributions of many species. On the other hand,
 optimum  temperatures  (such as those producing fastest
 growth rates) are not generally  necessary at all times to
 maintain thriving populations and  are  often exceeded in
 nature during summer months (Fry 1951 ;277 Cooper  1953 ;264
 Beyerle and  Cooper I960;246  Kramer and Smith I960297).
 Moderate  temperature  fluctuations can  generally  be
 tolerated as long as a maximum upper limit is not exceeded
 for long  periods.
   A true temperature limit  for exposures  long enough to
 reflect metabolic acclimation and optimum ecological per-
 formance must  lie  somewhere between the physiological
 optimum and the  ultimate upper incipient lethal tempera-
 tures.  Brett  (I960)254 suggested  that a provisional long-
 term exposure limit be  the temperature  greater than opti-
 mum that allowed  75 per cent of optimum performance.
 His suggestion has not been  tested by definitive studies.
   Examination  of literature  on  performance,  metabolic
 rate, temperature  preference, growth, natural distribution,
 and tolerance of several species has yielded an apparently
 sound theoretical basis for estimating an upper temperature
 limit for long term  exposure and a method for doing this
 with  a  minimum  of additional  research.  New data will
 provide refinement,  but this  method forms a useful guide
 for the present time. The method is  based on the  general
 observations summarized here and in Figure 111-4 (a, b,  c).
   1.  Performances  of organisms  over a range of tempera-
 tures are available in the scientific literature for a variety of
 functions. Figures  III-4a and b  show three characteristic
 types of responses numbered  1 through 3, of which  types 1
and  2 have  coinciding  optimum peaks. These optimum
 temperatures are characteristic for a species (or  life stage).
   2.  Degrees  of  impairment from  optimum levels  of
various  performance functions are not  uniform with  in-
 creasing temperature above the optimum for a single  species.
The most sensitive function appears to be growth rate,  for
which a  temperature of zero  growth  (with abundant food)
can  be determined  for  important species and life  stages.
 Growth rate of organisms appears to  be an integrator of all
 factors acting on an organism. Growth rate should probably
 be expressed as net biomass gain or net growth (McCormick
 et al. 1971)302 of the  population, to account for deaths.
   3.  The maximum temperature at which several species
 are consistently found  in nature  (Fry  1951 ;277 Narvi
 1970)306 lies near the average of the optimum temperatui
 and the temperature of zero net growth.
   4.   Comparison of patterns in Figures III-4a  and
 among different species indicates that while the trends a:
 similar, the optimum is closer to the lethal level in son
 species than it is in sockeye salmon. Invertebrates exhibil
 pattern of temperature effects on growth  rate that  is vei
 similar to that of fish (Figure III-4c).
   The optimum temperature may be influenced by rate <
 feeding. Brett et al. (1969)2'*7  demonstrated a shift in opt
 mum toward  cooler temperatures for sockeye  salmon wh«
 ration was restricted. In a  similar experiment with chann
 catfish, Andrews and Stickney  (1972)242 could see no sue
 shift. Lack  of a general shift in optimum may be  due 1
 compensating changes in  activity of the fish (Fry person
   These observations suggest  that an average of the opt
 mum temperature and the temperature of zero net growt
 [(opt. temp. + z.n.g. temp)/2] would be a useful estimate c
 a limiting weekly mean temperature for resident organism
 providing  the peak  temperatures do  not exceed  valui
 recommended  for short-term  exposures. Optimum growt
 rate would generally be reduced to no lower than 80 per cec
 of the  maximum if the limiting temperature is EIS  average
 above  (Table III-ll). This range of reduction from opt
 mum appears acceptable,  although there  are no quantit;
 tive studies  available that  would allow the criterion to 1:
 based upon a  specific level of impairment.
  The criteria for maximum upper temperature must allo1
 for seasonal changes, because different life stages of man
 species  will have different thermal  requirements for  th
 average of  their optimum cind zero net  growths. Thus
juvenile fish in May will be likely to have a lower maximui
 acceptable temperature than will the same fish in July, an
 this must be reflected in the thermal criteria for a waterbodi
  TABLE  III-ll—Summary  of  Some  Upper  Limiting.
  Temperatures in C, (for periods longer than one week)
  Based Upon Optimum Temperatures and Temperatures
                   of Zero Net Growth.

Catostomus commersoni (white sucker)
Coregonus artedii (Cisco or lake herring)

Ictalurus punctatus (channel catfish)

Lepomis ntacrochirus (blue(ill) (year II)
Micropterus salmoides (largemouth bass)
Notropis atherinoides (emerald shiner)
Salvelinus fontinalis (brook trout)







McCormick et al.
Strawn 1970"°
Andrews and Stickney
McComish 1971'<"
Strawn 1961">


opu mui


* National Water Quality Laboratory, Duluth, Minn., unpublished data.';'

                                                                                         Heat and Temperature/I 55
        Gross Conversion Efficiency
                                           10                   15
                                              Acclimation Temperature C
    After Brett 1971256
FIGURE III-4a—Performance of Sockeye Salmon (Oncorhynchus nerka) in Relation to Acclimation Temperature

 156/Section III—Freshwater Aquatic Life and Wildlife

   While  this approach  to  developing  the maximum sus-  sizeable body of data  on  the  ultimate incipient  leth
 tained temperature appears justified on the basis of available  temperature that could serve as a substitute for the data <
 knowledge, few limits can be derived from existing data in  temperature of zero net growth. A practical consideratic
 the literature on zero growth. On the other hand, there is a  in recommending criteria is the time required to condu

                                                                                         Heat and Temperature /157
 research necessary to provide missing data. Techniques for
 determining incipient lethal temperatures are standardized
 (Brett 1952)252 whereas those for zero growth are not.
   A temperature that is one-third of the range between the
 optimum temperature  and  the ultimate incipient lethal
 temperature that can be calculated  by the formula
  optimum temp. -)	
                ultimate incipient lethal temp.-optimum temp.
                                              (Equation I)
yields  values  that  are  very close to  (optimum temp. +
z.n.g. temp.)/2. For example, the values are, respectively,
32.7 and 32.8 C for channel catfish and 30.6 and 30.8 for
largemouth bass (data from Table III-8 and Appendix II).
This formula offers a  practical method for obtaining allow-
 •=   100
                         15      20      25      30
                          Temperature in C
         Anscll 1968 243

FIGURE III-4c—M. mercenaria: The general relationship
between temperature and the rate of shell growth, based on
field measurements of growth and temperature.
•: sites in Poole Harbor, England; Q: North American sites.
able limits, while retaining as its scientific basis the require-
ments of preserving adequate rates of growth. Some limits
obtained from data in the  literature are given  in  Table
111-12. A hypothetical example of the effect of this limit on
growth of largemouth bass is illustrated in Figure 111-5.
  Figure III-5 shows a hypothetical example of the effects
of the limit on maximum weekly  average temperature on
growth rates of juvenile largemouth bass. Growth data as a
function of temperature are from Strawn 196131
158/Section ///—Freshwater Aquatic Life and Wildlife
                   Annual Accumulated Growth
        250 —
                                        Elevated (with limit)
                                                                  Elevated (without limit)
                                      6       8       10
                                                  Ambient + 10 F
                             Average Ambient
                             (Lake Norman, N.C.)
                                                                                             Weekly Growth Rate
Weekly Growth Rate
(Ambient+ 10  F)
             0    7  14  21   28   4  11  18   25   4
                     JAN.           FEB.
                                   15   22  29  6   13  20   27  3
                                  APR.             MAY
10  17  24  1

                                                                            Heat and Temperature/\59
  FIGURE III-5—A hypothetical example of the effects of the limit on maximum weekly
 average temperature on growth rates of juvenile largemouth bass. Growth data as a function
 of temperature are from Strawn 1961; the ambient temperature is an averaged curve for Lake
 Norman, N.C., adapted from data supplied by Duke Power Company. A general temperature
 elevation of 10 F is used to provide an extreme example. Incremental growth rates (mm/wk )
 are plotted on the main figure, while annual accumulated growth is plotted in the inset.
 Simplifying assumptions were that growth rates and the relationship of growth rate to tem-
 perature were constant throughout the year, and that there would be sufficient food to sus-
 tain maximum attainable growth rates at all times.
                                       Max. Weekly Avg., largemouth bass
      Growth Rates


22  §
20  H





 15  22  29   5   12  19  26  2   9  16  23   30   7   14   21  28  4   11  18  25   2   9   16  23 30
JULY           AUG.             SEPT.           OCT.            NOV.               DEC.

160/Section III—Freshwater Aquatic Life and Wildlife

TABLE 111-12—Summary of Some Upper Limiting Temperatures for Prolonged Exposures of Fishes Based on Optimum Tern
                     peratures and Ultimate Upper Incipient Lethal Temperatures (Equation 1).
Catostomus commersom (white sucker)
Coregonus artedn (Cisco or lake herring)
Ictalurus punctatus (channel catfish)

Lepomis macrochirus (bluegill) (yr II)

Micropterus dolomieu (smallmouth bass)

Micropterus salmoides (largemouth bass)(fry)
Notropis atherinoides (emerald shiner)
Oncorhynchus nerka (sockeye salmon)

Pseudopleuronectes Americans (winter
Saimotrutta (brown trout)

Salvelinus fonti nalis (brook trout)

Salvelinus namaycush (lake trout)



ave 27.3

8 to 17
ave 12.5
ave 14 5

ave 16.5





— Function



other functions
max. swimming


scope for activity
(2 metabol:sm)
swi mmmg speed

unpubl., NWQL™-
McCormicketal. im>«
Strawn 197Q;3M Andrews and Stickney
McComish 1971»°i
Anderson 1959™
Horning and Pearson 1972291
Peek 19653M

Strawn 1961319
unpubl., NWQLI2»
Brett et al. 19692"
Brett 19712S«

Brett 1970^5
Brett 1970!ss

unpubl, NVVQL'2'
Baldwin 195J»»
Graham 19492'1

Gibson and Fry 19542"

Ultimate upper incipient Maximum weekly average
lethal temperature Reference temperature (Eq 1)







84.7 Hart194728s 27.8
78.3 Edsall and Colby 1970™ 19.2
100. 4 Allen and Steam 1968™ 32. 1

92.8 Hart1952» 25.9

95.0 Horning and Pearson 1972291 29.9

97.5 HarH9522»6 30.5
87.3 Hart19522»« 28.2
77.0 Brett 19522*2 18.3

84.4 HoffandWestmanW9 21.8
74.3 Bishai I9602" 16 2

77. 9 Fiy, Hart and Walker, 1946=" 18. 2

(iibson and Fry 19542<" 18.8


78. 6

85 8


61 2



  Heat added to upper reaches of some cold rivers can be
retained  throughout  the  river's remaining length  (Jaske
and Synoground 1970).292 This factor adds to the natural
trend  of warming at  distances from headwaters.  Thermal
additions in headwaters,  therefore, may  contribute sub-
stantially to reduction of cold-water species in downstream
areas  (Mount 1970).305 Upstream thermal additions should
be evaluated for their effects on summer maxima  at down-
stream locations, as well  as in the immediate vicinity of
the heat source.


  Growth of aquatic organisms would be main-
tained at levels  necessary for sustaining  actively
growing and reproducing populations if the maxi-
mum weekly average temperature in the zone in-
habited  by the species at that time does not exceed
one-third of the range  between the optimum tem-
perature and  the ultimate upper incipient lethal
temperature of the species (Equation 1, page 157),
and the  temperatures above the weekly average do
not exceed the criterion for  short-term exposures.
This  maximum need not apply to acceptable mix-
ing zones (see proportional relationships of mixing
zones to receiving systems, p. 114), and must be
applied with adequate understanding of the normal
seasonal distribution of the important species.

  Although  artificially produced  temperature  elevatiot
during winter months  may actually bring the temperatui
closer to optimum or preferred temperature for importat
species and attract fish  (Trembley  1965),321  metaboli
acclimation to these higher levels can preclude safe retur
of the organism to  ambient temperatures should  th
artificial heating suddenly cease (Pennsylvania Fish Con
mission 1971;310 Robinson  1970)316 or the organism  I;
driven from the heat  area.  For example,  sockeye salmo
(Oncorhynchus nerka) acclimated to 20 C suffered 50 percei
mortality in the laboratory when their temperature wj
dropped suddenly to 5 C (Brett 1971:256 see Figure III-3
The same population of fish withstood a drop to zero whe
acclimated to 5 C. The lower limit of the range of therms
tolerance of important species must,  therefore, be mair
tained at  the  normal  seasonal  ambient  temperature
throughout cold seasons, unless special provisions are mad
to assure that rapid temperature drop will not occur or tha
organisms cannot become acclimated to elevated tempera
tures.  This can be accomplished by limitations on tempera
ture elevations in such areas as discharge canals and mixin;
zones  where organisms may  reside, or by insuring tha
maximum temperatures occur only in areas not accessibl
to important  aquatic life for lengths of time sufficient  ti
allow  metabolic acclimation. Such inaccessible areas wouli
include the high-velocity zones of diffusers or screened dis

                                                                                        Heat and Temperature /161
charge channels. This reduction of maximum temperatures
would not preclude use of slightly warmed areas as sites for
intense winter fisheries.
  This consideration may be important in some regions at
times other than in winter.  The Great Lakes, for example,
are susceptible to rapid changes in elevation of the thermo-
cline  in  summer which may induce  rapid decreases in
shoreline temperatures.  Fish acclimated to exceptionally
high  temperatures in discharge canals may be killed or
severely stressed without changes in  power plant opera-
tions  (Robinson 1968).314 Such regions should take special
note of this possibility.
  Some numerical values for acclimation temperatures and
lower limits  of tolerance  ranges  (lower  incipient  lethal
temperatures) are given in Appendix II-C. Other data must
be provided  by further research. There  are no adequate
data available with which to estimate a safety factor for no
stress from cold shocks. Experiments currently in progress,
however, suggest that channel catfish  fingerlings are more
susceptible to predation after being cooled more than 5 to
6 C (Coutant, unpublished data).324
  The effects of limiting ice formation in lakes and rivers
should be carefully  observed.  This aspect of maximum
winter temperatures  is apparent,  although there is insuffi-
cient  evidence to estimate  its importance.


  Important species  should be  protected if  the
maximum weekly  average temperature during win-
ter months in any area to which they have access
does not   exceed   the  acclimation  temperature
(minus  a  2 C safety factor)  that raises  the  lower
lethal threshold temperature of such species above
the normal ambient water temperatures for that
season,  and the criterion for short-term exposures
is not exceeded. This recommendation applies es-
pecially to  locations where organisms may be at-
tracted  from the receiving water and subjected to
rapid thermal drop, as  in the low velocity areas of
water diversions (intake or discharge), canals, and
mixing zones.


  To protect aquatic life and yet allow  other uses  of the
water, it  is essential to know the lengths of time organisms
can survive extreme  temperatures (i.e., temperatures  that
exceed  the   7-day  incipient  lethal  temperature).  Both
natural environments and power plant cooling systems can
briefly reach  temperature extremes (both upper and lower)
without  apparent detrimental  effect  to the aquatic  life
(Fry  1951 ;277 Becker et al.  1971).245
  The length of time that  50 per cent of a population will
survive temperature above  the incipient lethal temperature
can be  calculated from  a regression equation of experi-
mental data (such as those in Figure III-3) as follows:

               log  (time) =a+b (temp.)     (Equation 2)

where time is expressed in minutes, temperature in degrees
centigrade  and where a and  b are intercept and slope,
respectively, which  are characteristics of each acclimation
temperature for each species.  In  some cases the  time-
temperature relationship is more complex than the  semi-
logarithmic model given above. Equation  2,  however,  is
the most applicable, and is  generally  accepted  by the
scientific community (Fry  1967).279 Caution  is  recom-
mended  in extrapolating beyond  the  data limits of the
original research (Appendix II-C). The rate of temperature
change does not appear to alter this equation, as long as the
change occurs more rapidly than over several days (Brett
1941 ;251  Lemke  1970).30°  Thermal  resistance  may  be
diminished by the  simultaneous presence of toxicants or
other debilitating factors (Ebel et al. 1970,273 and summary
by Coutant 1970c).269 The most accurate predictability can
be derived from data collected using water from the site
under evaluation.
  Because  the  equations based on  research on  thermal
tolerance predict 50 per cent mortality, a  safety  factor  is
needed  to assure no mortality. Several studies have indi-
cated that a 2 C reduction of an upper stress temperature
results in no  mortalities within  an equivalent exposure
duration (Fry et al. 1942;280 Black 1953).248  The validity
of a two degree safety factor was strengthened by the results
of Coutant  (1970a).267  He  showed that about 15 to  20
per cent of the exposure time, for median mortality at a given
high temperature, induced selective predation on thermally
shocked salmon and trout. (This also amounted to reduction
of the effective  stress temperature  by about 2 C.) Un-
published data  from subsequent  predation  experiments
showed that this reduction of about 2 C also applied to the
incipient lethal temperature. The level at which there is no
increased vulnerability to predation is the best estimate of a
no-stress exposure  that  is currently available. No similar
safety factor has been explored for tolerance of low tem-
peratures.  Further  research may determine  that safety
factors,  as  well  as  tolerance limits, have  to  be  decided
independently for each species, life stage, and water quality
  Information needed for predicting survival  of a number
of species of fish  and invertebrates under short-term condi-
tions of heat extremes is presented in Appendix II-C. This
information includes  (for each acclimation temperature)
upper and lower incipient lethal temperatures: coefficients
a and b for the thermal resistance equation; and information
on size,  life stage,  and  geographic source  of the  species.
It is clear that adequate data are available for only a  small
percentage of aquatic species, and additional research  is
necessary.  Thermal  resistance  information  should  be
obtained locally for critical areas to account for simul-

 \&l/Section III—Freshwater Aquatic Life and Wildlife
taneous presence of toxicants or other debilitating factors,
a consideration not reflected in Appendix II-C data. More
data are available for upper lethal temperatures than for
  The resistance  time  equation,  Equation  2,  can  be
rearranged to incorporate the 2 C margin of safety and also
to define conditions for survival (right side of the equation
less than or equal to 1) as follows:
                   1 > —
(Equation 3)
  Low levels of mortality of some aquatic organisms are not
necessarily detrimental to ecosystems, because permissible
mortality  levels can be established. This is how fishing or
shellfishing activities are managed. Many states and inter-
national  agencies  have  established  elaborate  systems for
setting an allowable rate of mortality (for sport and com-
mercial fish) in order to assure  needed reproduction and
survival.  (This should not imply, however, that a form of
pollution should be allowed to take the entire harvestable
yield.) Warm discharge  water  from a power plant may
sufficiently stimulate reproduction of some organisms (e.g.,
zooplankton), such that those killed during passage through
the maximally heated areas are replaced within a few hours,
and no impact of the mortalities can be found  in the open
water (Churchill and Wojtalik  1969;262 Heinle  1969).288
On the other hand, Jensen (1971)293 calculated that even
five percent additional  mortality of  0-age  brook trout
(Salvelinus Jontinalis) decreased the yield of the trout fishery,
and 50 per cent additional mortality would, theoretically.
cause extinction of the population. Obviously, there can be
no adequate generalization concerning the impact  of short-
term  effects on  entire ecosystems, for each case will  be
somewhat  different. Future  research  must  be  directed
toward determining the effects of local temperature stresses
on population dynamics. A complete discussion will not be
attempted here. Criteria for complete short-term protection
may not always be necessary and  should be applied with an
adequate understanding of local conditions.

  Unless  there  is justifiable reason  to  believe it
unnecessary for maintenance of populations of a
species,  the right  side of  Equation 3   for  that
species should  not be allowed  to increase above
unity when the temperature exceeds the incipient
lethal temperature minus 2  C:
                  1 >
Values for a and b at the appropriate acclimation
temperature for some species can be obtained from
Appendix II-C or through additional research if
necessary data are not available. This recommen-
dation applies to all locations where organisms •
be  protected  are exposed, including areas withi
mixing zones and water diversions such  as pow
station cooling water.


  The sequence of events relating  to gonad growth  ai
gamete maturation, spawning migration, release of garnet<
development of the egg and embryo, and commenceme
of independent feeding represents one of the  most compl
phenomena in  nature, both for  fish  (Brett  1970)256  ai
invertebrates (Kinne  1970).2'6 These events  are genera
the most thermally sensitive of all life stages. Other envirc
mental factors, such as light and salinity, often seasonal
nature, can also profoundly affect the response to ternpei
ture (Wiebe 1968).323 The general physiological state oft
organisms (e.g., energy reserves), which is an integration
previous history, has a strong effect on reproductive pott
tial (Kinne 1970).296 The erratic sequence of failures  a
successes of different year classes  of lake fish  attests to  t
unreliability of natural conditions for providing optirm.
  Abnormal, short-term temperature fluctuations appear
be of greatest significance in reduced production of juven
fish  and  invertebrates  (Kinne,  1963).295  Such  them
fluctuations can  be a  prominent consequence of water  i
as in hydroelectric power (rapid changes in river flow rate
thermal electric power (thermal  discharges  at fluctuati
power levels),  navigation  (irregular  lock releases),  a
irrigation   (irregular water  diversions  and  wasteway  '
leases). Jaske and Synoground  (1970)292 have document
such temperature changes due  to interacting thermal  a
hydroelectric discharges on the Columbia River.
  Tolerable limits  or variations of temperature  char
throughout development, and particularly  at  the  m
sensitive life stages,  differ  among species.   There is
adequate summary of data on  such thermal  requireme
for successful reproduction. The data are scattered throu
many  years of  natural history  observations  (however, :
Breder and Rosen 1966250 foi a recent compilation of so)
data; also see Table 111-13). High priority must be assign
to summarizing existing information  and obtaining  tt
which is lacking.
  Uniform elevations  of  temperature  by a few  degr<
during the spawning period, while maintaining short-te.
temperature cycles  and seasonal thermal patterns, app{
to have little overall  effect on the reproductive cycle
resident aquatic species, other than to advance  the timi
for spring spawners or delay it for fall spawners.  Such sh:
are often seen in nature, although no quantitative measu
ments  of  reproductive success have  been  made  in  t
connection. For  example,  thriving populations of ma
fishes occur in diverse streams of the Tennessee Valley
which the date of the spawning temperature may vary  ir

                                                                                Heat and Temperature/163

TABLE 111-13—Spawning Requirements of Some Fish, Arranged in Ascending Order of Spawning Temperatures
                       (Adapted from Wojtalik, T. A., unpublished manuscript)*
Stizostedioncanadense. ...
S. vitreum vitreum 	
Longnose gar
Lepisosteus osseus ..
White bass
Morone chrysops 	
Least darter
Etheostoma microperca .
Spotted sucker
Minytrema melanops
White sucker
Catostomus commersom ...
Silvery minnow
Hybognathus nuchalls. .
Banded pygmoiimfisli
Elassoma zonatum
White crappie
Pomoxis annuiaris ...
Fathead minnow
Bigmouth buffalo
Largemouth bass
Micropterus salmoides
Common shiner
Notropis cornutus 	
Golden shiner
Notemigonus crysoktucas 	
Green sunflsh
Lepomis cyanellus ...
Pofyodon spathufa
Blackside darter
Percina maculata
Gizzard shad
Dorosoma cepedianum .
Smallmouth bass
Micropterus dotomieui.
Spotted bass
Micropterus punctubtus .
Johnny darter
Etheostoma nigrum ....
Orange spotted sunflsh
Lepomis humilii . .
Smallmouth buflalo
Icb'obus hubalus
Black buffalo
1. niger . ...
Cyprinus carpio ....
Lepomis macrochirus 	
Redbreast sunflsh
Channel calf sh
Ictalurus punctatus 	
White catfish
1 catus
Lepomis gibbosus . . .
Black crappie
Pomoxis nigromaculatus
Brook silverside
Labidesthes sicculus 	
Brown bullhead 	
Ictalurus nebulosus ....
Threadfin shad
Dorosoma petenense 	
Lepomis gulosus 	
River redhorse

.. . 10.8
. 14.0-16.0
.. . . 26.7
20 0
20 0
20 0

21 1

Spawning site
Shallow gravel ban
Gravel, rubble, boulders on bar
Flooded shallows
Sand & rock shores

Streams or bars

Submerged materials in shallows
Shallows near bank
Small gravel streams
Bays I shoals, weeds
Bank, shalows
Over gravel bars

Gravel rock shore
Small streams, bar

Flooded shallows
Weeds, shallows

Bank cavity
Sand gravel bar
Bank shallows

Over gravel

Shallows, weeds
Shallow and open water
Bank shallows

Range in spawning depth
2-4 feet
3-10 feet
Flooded shallows
2-12 feet

Nr. surface
30 inches
Inches to \yt feet
Nr. surface

3-20 feet

Nr. surface
2-6 feet

< 10 feet


Inchest) 6 feet

Daily spawning time
Day, right
Day, tang but esp. night

. . Day, night
. Day

Night day

.. Day

Day night

Day, night





Underside floating objects




Weeds, bottom

. Weeds, bottom

Incubation period
(ays (Temp. C)
25 (5.0)
6 (20.0)
2 (15.6)

1 (21.1-23.2)
9-10 (18.7)
5 (18.9)
4 (15.6+)

7 (15.0)
4-5 (20.0)

4-8 (16.7)
1J4-3 (22.2)

9-10 (15.0)
6-7 (23.9-29.4)
3 (27.8)

5 (25.0)
1H (25.0-26)7)

 164:/Section III—Freshwater Aquatic Life and Wildlife

 TABLE 111-13—Spawning Requirements of Some Fish, Arranged in Ascending Order of Spawning Temperatures—Contin
Blue catfish
Ictalurus furcatus 	
Flathead catfish
Redear sunfish
Upturns microlophus . .
Ungear sunfish
L. megalotis
Freshwater drum
Apiodinotus grunniens 	
River carpsucker
Spotted bullhead
Ictalurus serracanthus
Yellow bullhead
1. natalis
Temp. (C) Spawning site Range in spawning depth



23.0 Quiet, various Inches to 10 feet

. 23.3


. .. 23.9

. 26.7

Quiet, shallows 1' ,-4 feet
Daily spawning time Egg site Incubation pe
days (Temp.

Bottom 5-10 (18.9)
 * T. A. Wojtalik, Tennessee Valley Authority, Muscle Shoals, Alabama.---"'
given year by 22 to 65 days. Examination of the literature
shows that shifts in spawning dates by nearly one month
are common in natural waters throughout the U.S.  Popula-
tions of some species at the southern limits  of their dis-
tribution are exceptions, e.g., the lake whitefish (Coregonus
clupeaformis)  in  Lake Erie that  require a prolonged, cold
incubation period (Lawler  1965)299  and species  such  as
yellow perch (Perca flavescens) that require a long chill period
for egg maturation prior to spawning  (Jones,  unpublished
   This biological plasticity suggests that the annual spring
rise, or fall drop, in temperature might safely be advanced
(or delayed) by nearly one month in many regions, as long
as the thermal requirements that are necessary for migra-
tion, spawning,  and other activities are not eliminated and
the necessary chill periods, maturation times, or incubation
periods are preserved for important species. Production of
food organisms  may  advance in a similar way, with little
disruption of food chains, although there is little evidence to
support this  assumption (but see Coutant 1968;266  Coutant
and Steele 1968;271  and Nebeker 1971).307 The process is
similar to the latitudinal differences within the range of a
given species.
  Highly  mobile  species that  depend  upon  temperature
synchrony among widely different regions or  environments
for various phases of the reproductive or rearing cycle (e.g.,
anadromous salmonids or aquatic insects)  could be faced
with dangers of dis-synchrony if one area is  warmed, but
another is not. Poor  long-term success of one year class of
Fraser River (British Columbia)  sockeye salmon (Oncorhyn-
chus nerka) was attributed to early (and highly successful)
fry production and emigration during an abnormally warm
summer  followed  by  unsuccessful,  premature  feeding
activity in the cold and still unproductive estuary  (Vernon
1958).322 Anadromous species are able, in some cases, (see
studies of eulachon  (Thaleichthys pacificus)  by Smith and
Saalfeld 1955)317 to modify their migrations and spawn
to coincide  with  the proper temperatures whenever ;
wherever they occur.
  Rates of embryonic development that could lead to p
mature hatching  are determined by  temperatures  of
microhabitat of the  embryo. Temperatures of  the  mk
habitat may be quite different from those of the remain
of the  waterbody.  For example, a thermal effluent at
temperature  of maximum water density (approximat
4 C) can sink in a lake whose surface water temperat
is  colder (Hoglund  and  Spigarelli,   1972).290  Incubat
eggs of such species as lake (.rout (Salvelinus namqycush) i
various coregonids on the lake bottom may be intermitter
exposed to temperatures warmer than  normal.  Hatch
may be advanced to dates that are too early for surviva
the fry in their  nursery  areas. Hoglund arid  Spigai
1972,290 using temperature data from a sinking plume
Lake Michigan, theorized that if lake  herring  (Coregc
artedii)  eggs  had been incubated at the  location of one
their temperature sensors, the fry would have hatcl
seven days early. Thermal limitations must, therefore, ap
at the proper location for the particular species or life st;
to be protected.
  After their specific  limiting temperatures  a
exposure times  have been determined  by stud
tailored to local conditions,  the reproductive j
tivity  of selected species will be protected in ar<
• periods required for gonad  growth and gam<
  maturation are preserved;
• no  temperature differentials  are created  tli
  block spawning migrations, although some del
  or advancement of timing based  upon local co
  ditions may be tolerated;

                                                                                    Heat and Temperature /165
• temperatures are not raised to a level at which
  necessary spawning or incubation temperatures
  of winter-spawning species cannot occur;
• sharp temperature changes are  not induced  in
  spawning areas, either  in mixing  zones  or  in
  mixed water bodies (the  thermal and geographic
  limits to such changes will be dependent upon
  local  requirements  of  species,  including the
  spawning microhabitat, e.g.,  bottom gravels,
  littoral zone,  and  surface strata);
• timing of reproductive events is not  altered  to
  the extent that synchrony is broken where repro-
  duction or rearing of certain life stages is shown
  to be dependent upon cyclic food sources or other
  factors at remote locations.
• normal patterns of gradual temperature changes
  throughout the year are maintained.

These requirements should supersede  all  others
during times when they apply.


  Significant change in  temperature or in thermal patterns
over a  period of time may cause some change in the com-
position of aquatic communities (i.e., the species represented
and the numbers of individuals in each species). This has
been documented by field studies at power plants (Trembley
1956-I960)321 and by laboratory investigations (Mclntyre
19h8).3ra Allowing temperature changes to alter significantly
the community  structure in natural waters  may be detri-
mental, even  though species of direct importance  to man
arc not eliminated.
  The  limits of allowable change in species diversity due to
temperature changes should not differ from those applicable
to any  other pollutant. This  general topic is treated in
detail  in reviews  by others  (Brookhaven  National Lab.
1969)25S and is  discussed in Appendix  II-B,  Community
Structure and Diversity  Indices, p. 408.


  Alteration of aquatic communities by the addition of heat
may occasionally result in  growths of nuisance organisms
provided that other environmental conditions essential to
such growths (e.g.,  nutrients)  exist.  Poltoracka  (1968)311
documented the growth  stimulation of plankton in  an
artificially  heated small   lake; Trembley  (19653-1) re-
ported dense growths  of attached algae in the discharge
canal and shallow discharge plume of a power station (where
the algae  broke loose periodically releasing decomposing
organic matter to the receiving water).  Other instances of
algal growths in effluent channels of power stations were
reviewed by Coutant (1970c).269
  Changed thermal patterns (e.g., in stratified lakes) may
greatly  alter  the  seasonal  appearances of nuisance algal
growths even though the temperature changes are induced
by altered circulation patterns (e.g., artificial destratifica-
tion). Dense growths of plankton have  been retarded in
some instances and stimulated in others (Fast 1968;275 and
unpublished data 1971).325
  Data  on temperature limits or thermal distributions in
which nuisance growths will be produced are not presently
available due in part to the complex interactions with other
growth  stimulants.  There is not  sufficient evidence to say
that  any  temperature increase  will  necessarily result in
increased nuisance organisms. Careful evaluation of local
conditions is  required  for any  reasonable prediction of

  Nuisance  growths  of  organisms may develop
where there are increases in temperature or alter-
ations  of the temporal or spatial  distribution of
heat in water. There should be careful evaluation
of all factors contributing to nuisance growths at
any site before  establishment of  thermal  limits
based  upon  this response, and temperature limits
should be set in conjunction with restrictions on
other factors (see the discussion of  Eutrophication
and Nutrients in Section I).

  Recommendations  for  temperature  limits to  protect
aquatic life consist of the following two upper limits for any
time of the year (Figure 111-6).

  1.   One limit consists  of a maximum weekly average
temperature that:
     (a)  in the warmer months  (e.g., April  through
        October  in  the  North,  and  March  through
        November in the South) is one third of the range
        between  the   optimum  temperature  and  the
        ultimate upper incipient  lethal temperature for the
        most  sensitive important species (or appropriate
        life stage)  that is normally found  at that location at
        that time;  or
     (b) in the cooler months (e.g.,  mid-October to mid-
        April in the North, and December to February in
        the South) is that elevated temperature from which
        important species die when that  elevated  tem-
        perature  is suddenly  dropped  to the normal
        ambient temperature, with  the limit  being the
        acclimation temperature  (minus  a  2 C  safety
        factor), when the lower  incipient lethal tempera-
        ture equals the normal ambient water temperature
        (in some regions this limit may also be applicable
        in summer); or
     (c)  during reproduction  seasons (generally April-June
        and September-October in the North, and March-
        May  and  October-November in  the South) is that

     lection HI—Freshwater Aquatic Life and Wildlife
        temperature that meets specific site requirements
        for successful migration, spawning, egg incubation,
        fry rearing, .and other reproductive functions of
        important species; or
    (d)  at -a  specific  site is found necessary to preserve
        normal species diversity or prevent undesirable
        growths of nuisance organisms.
  2.   The second limit is the time-dependent maximum
temperature for short exposures as given by the species-
specific equation:
                  1 >
  Local requirements for reproduction should supersede
all other requirements when they are applicable. Detailed
ecological  analysis  of both  natural and  man-modified
aquatic environments is necessary to ascertain when these
requirements should apply.

     A hypothetical electric power station using lake water i
   cooling is illustrated as a typical example in Figure III
   This discussion concerns the application of thermal critei
   to this typical situation.
     The size of the power station is 1,000 megawatts elect.
   (MWe) if nuclear, or  1,700 MWe if fossil-fueled (oil, co
   gas); and it  releases 6.8  billion  British  Thermal Un
   (BTU) per hour to the aquatic environment. This size
   representative of power stations currently being instalk
   Temperature  rise  at the  condensers would be  20 F wi
   cooling water flowing at the rate of 1,520 cubic feet/secoi
   (ft3/sec) or 682,000 gallons/minute. Flow could  be  i
   creased to reduce temperature rise.
     The schematic Figure III-7 is drawn with two alternati
   discharge arrangements to illustrate the extent to whii
   design features affect thermal impacts upon aquatic li
    30 -- 86
                                                                                 Heat and Temperature/\ 67
       Canal (2 mi.)






               "~  Temperature
                                       Historic             \ \
                                       Average Temp, at D	  \ \
                  JFMAMJJ   ASOND

                                                                              Plume Scale
                                                                         I   i    i
FIGURE IH-7—Hypothetical Power Plant Site For Application of Water Temperature Criteria

 168/Section HI—Freshwater Aquatic Life and Wildlife
Warm condenser water can be carried from the station to
the lake by (a) a pipe carrying water at a high flow velocity
or (b) a canal in which the warm water flows slowly. There
is  little cooling in a canal, as measurements at several
existing power stations have shown. Water can be released
to the lake by using any of several combinations of water
velocity and volume (i.e.,  number of outlets)  or outlet
dimensions and locations. These  design features largely
determine the configuration  of the thermal plumes illus-
trated in Figure III-7 resulting from  either rapid dilution
with lake water or from slow release as a surface layer. The
isotherms  were placed  according  to computer simulation
of thermal discharges (Pritchard 1971)312 and represent a
condition without  lake currents to aid mixing.
  Exact configuration of  an actual plume depends upon
many factors (some of which  change seasonally  or even
hourly) such as local patterns of currents, wind, and bottom
and shore topography.

Analytical Steps
  Perspective of the organisms in the water body and of the
pertinent  non-biological  considerations  (chemical,   hv-
drological,  hydraulic)  is  an  essential   beginning.  This
perspective requires a certain amount of literature survey-
or on site study if  the information  is not  well known. T\vo
steps are particularly important:

  1.  identification of  the  important species  and  com-
munity (primary production, species diversity, etc.) that are
relevant to this site; and
  2.  determination of life patterns of the important species
(seasonal distribution, migrations,  spawning areas, nursery
and rearing areas, sites of commercial or sport fisheries).
This information should include as much specific informa-
tion on thermal requirements as  it is possible  to obtain
from the literature.

  Other steps relate the life  patterns and environmental
requirements of the biota to the sources of potential thermal
damage from the power plant. These steps can be identified
with specific  areas in Figure  III-7.

Aquatic Areas Sensitive to Temperature Change

  Five principal areas offer potential for biological damage
from thermal changes, labeled A-E on  Figure III-7. (There
are other areas associated with mechanical or  chemical
effects that cannot be treated here; see the index.)

  Area A  The cooling water as it passes through the intake,
          intake piping (Ai), condensers, discharge piping
          (A2)  or  canal (A'2), and thermal plume (A3 or
          A'3), carrying with it small organisms (such as
          phytoplankton, zooplankton, invertebrate larvae,
          and  fish eggs or larvae). Organisms receive a
          thermal shock  to  the full  20 F above  ambient
          temperature wilh a duration that depends uf
          the rate of water flow and the  temperature di
          in the plume.
  Area B  Water  of the  plume alone that entrains  b
          small and larger organisms (including small fi
          as it is diluted (B  or  B'). Organisms  rece
          thermal shocks from temperatures ranging fr
          the discharge  to the  ambient temperature,
          pending upon where they  are entrained.
  Area C  Benthic environment where bottom organi;
          (including fish eggs) can be heated chronically
          periodically  by the thermal plume (C or C')
  Area D  The slightly  warmed mixed water body (or la
          segment of it)  where all organisms experienc
          slightly warmer average temperature (D).
  Area E  The discharge canal in which resident or seaso
          populations  reside  at abnormally high tempe
          tures (E).

Cooling Water Entrainment
  It is not adequate to  consider only thermal criteria
water bodies alone when large numbers of aquatic organis
may be pumped  through a power plant. The probabil
of an organism being  pumped through  will depend up
the ratio of the volume of cooling water in the plant to 1
volume in the lake (or  to the volume  passing the plant ii
river  or tidal  fresh water}.  Tidal  environments  (be
freshwater and saline)  offer  greater potential for entra
ment than  is apparent,  s\nce the same water mass  v
move back and forth past the plant many times during 1
lifetime  of  pelagic  residence time  of  most organisi
Thermal shocks that could  be  experienced  by organis
entrained  at the  hypothetical power  station are shown
Figure III-8.
  Detrimental effects of thermal exposures received duri
entrainment can be judged by using the following equati
for short-term exposures  to extreme temperatures:
           General criterion. 1>
Values for a and b in the equation for the species of aqua
organisms that are likely to be pumped with cooling wa
may be obtained from Appendix II, or the data may
obtained using the methods of Brett (1952).262 The prevaili
intake  temperature  would  determine  the  acclimati
temperature to be selected from the table.
  For example, juvenile largemouth bass may frequent t
near-shore waters of this lake and be drawn into the intal
To determine whether the hypothetical thermal dischart
(Figure III-7) would be detrimental for juvenile bass,  t
following analysis can  be made (assuming, for examp
that the lake is in Wisconsin where these basic data for b;
are available):
       Criterion for juvenile  bass (Wisconsin) when inta


               Piping •
           Intake Piping

                        Can a
Dilution Plume
                                                      Canal Plume
                                                12       16        20        24

                                                lime \fu-r Initial Heating (his )
      Modified aflcr Coutant I970c269
                                                                                            //ifat and Temperature/\ 69
                                                                                                     36       40
FIGURE IH-8—Time Course of Temperature Change in Cooling Water Passing Through the Example Power Station with
                   Two Alternate Discharges. The Canal Is Assumed to Flow at a Rate of 3 Ft. Per Sec.
    temperature (acclimation) is  70 F  (21.11  C).  (Data
    from Appendix II-C).
                                      ploying rapid dilution.
                    10134- 3649-0. 97 8 9 (temp.+2) J
       Criterion applied to entrainment to end of discharge
    canal (discharge temperature is 70 F plus the 20 degree
    rise in the condensers or 90 F (32.22 C). The thermal
    plume would provide additional  exposure  above the
    lethal threshold, minus 2 C (29.5 C or 85.1 F) of more
    than four hours.
                    1Q [34. 364 9- 0.9 7 89(32. 22+2)]

       Juvenile bass  would not survive to the end of the
    discharge canal.


       Criterion applied to entrainment in the system em-
                                                                           1  >
                                                                               }Q[34. 3649-0. 9789(32. 22+2.0)]
                                      Travel time in piping to discharge is  assumed to be
                                      1  min., and temperature drop to below the lethal
                                      threshold minus 2 C (29.5 C or 85.1 F)  is about 10 sec.
                                      (Pritchard, 197 1).312


                                        Juvenile bass would survive this  thermal exposure:


                                        By using the  equation  in the following form,

                                                log (time)=a+6 (temp. + 2)

                                      the  length  of time that bass could barely survive the
                                      expected temperature rise could  be calculated, thus
                                      allowing selection of an appropriate discharge system.
                                      For example:

                                           log (time) =34.3649- 0.9789 (34.22)
                                           log (time) =0.8669
                                                time =7.36

 170/Section HI—Freshwater Aquatic Life and Wildlife
       This would be about 1,325 feet of canal flowing at
     3 ft/sec.
  It is apparent that a long discharge canal, a nonrecircu-
lating cooling pond, a very long offshore oioe, or delayed
dilution in a mixing zone (such as the one promoting surface
cooling) could prolong the duration of exposure of pumped
organisms and thereby increase the likelihood of damage to
them. Precise information on the travel times of the cooling
water in the discharge system is needed to conduct this
  The calculations have ignored changing temperatures in
the thermal plume,  because the canal alone was lethal, and
cooling in the plume with rapid dilution  was so rapid that
the additional exposure was only for 10 seconds (assumed to
be  at the discharge temperature the whole time). There
may  be  other  circumstances  under which the  effect  of
decreasing exposure temperature  in  the plume may  be
of interest.
  Effects of changing  temperatures in the plume can  be
estimated by summing the effects of incremental exposures
for  short time periods (Fry et al. 1946281). For example, the
surface cooling plume of Figures III-7  and III-8 could  be
considered to be composed of several short time spans, each
with  an average temperature,  until the  temperature had
dropped  to  the upper lethal  threshold minus  2 C for the
juvenile bass. Each  time period would be calculated as if
it were a single exposure, and the calculated values for  all
time periods would be summed and compared with unity,
as follows:
.1+2)] ~T JQ[a+b(temp.2+2)]
  The surface cooling plume of Figure III-6 (exclusive of
the canal) could  be considered to  consist of  15 min at
89.7 F (32.06 C),  15 min at 89.2 F  (31.78C),  15 min at
88.7 F (31.4 C), 15  min at 88.2 F (31.22 C),  15  min at
87.8 F (31.00 C), until the lethal threshold for 70 F acclima-
tion minus 2 C (85.1  F) was reached. The calculation would
proceed as follows:
1 >
     JQ [34.3649—0.9789(32.06+2)]

  In this case, the bass would not survive through the first
15-minute period. In other such calculations, several steps
would have to be summed before unity was reached (if not
reached, the plume would not be detrimental).

Entrainment in the Plume
  Organisms mixed with the thermal plume during dilution
will also receive thermal  shocks, although the maximum
temperatures  will generally be  less than  the  discharge
temperature. The number of organisms affected to son
degree  may be  significantly  greater than  the  numbe
actually pumped through the plant. The route of maximu
thermal  exposure for each  plume is indicated in  Figu
III-7 by a dashed line. This route should be analyzed
determine the maximum reproducible effect.
  Detrimental effects of these exposures can also be judgi
by using the criterion for short-term  exposures to extren
temperatures. The analytical steps were outlined above f
estimating the effects on organisms that pass through tl
thermal plume portions of the entrainment thermal patter
There would have been no mortalities of the largemou
bass from entrainment in the plume with rapid d ilution, di
to the short duration of exposure (about 10 seconds). Ai
bass that were entrained in  the near-shore portions of tl
larger plume, and remained in it, would have died in k
than 15 minutes.

Bottom  Organisms Impacted by the Plume
  Bottom  communities  of invertebrates,  algae,  root<
aquatic  plants, and many  incubating fish  eggs  can  1
exposed  to  warm plume water,  particularly in  shallo
environments. In some circumstances the warming can I
continuous,  in others it can be intermittent due to chang
in plume configuration with changes in currents, winds, i
other factors. Clearly a thermal plume that stratifies  ar
occupies only the upper part of the water column will ha1
least effect on bottom biota.
  Several approaches are useful in evaluating effects on tl
community. Some have predictive capability, while othe
are suitable largely  for identifying effects  after they  ha'
occurred. The criterion for short-term exposures identifie
relatively brief periods  of detrimental high temperature
Instead  of the organism passing through zones of elevate
temperatures, as in the previous examples, the organism
sedentary, and the thermal pulse passes over it. Developii
fish eggs may be very sensitive to such changes. A bri
pulse of high temperature that kills large numbers of org
nisms may affect  a bottom area for time periods far long
than the immediate  exposure time. Repeated sublethal e
posures  may also be detrimental, although the process
more complex than  straight-forward  summation. Analy;
of single exposures proceeds exactly as described for plun
  The criterion for prolonged exposures is more general
applicable. The maximum tolerable  weekly  average  ten
perature may be  determined by the organisms present an
the phase of their life  cycle.  In  May, for  example, tit
maximum heat tolerance temperature for the communii
may be  determined by incubating fish eggs or fish fry on tl
bottom.  In July  it may be determined by the importai
resident invertebrate species. A well-designed thermal di
charge should not require an extensive mixing zone whei
these criteria are exempted. Special criteria for reproducth
processes may have  to be applied, although  thermal di

                                                                                          Heat and Temperature/171
charges  should  be located  so  that  zones important  for
reproduction—migration, spawning,  incubation—are not
  Criteria  for species diversity provide a useful tool  for
identifying  effects  of thermal  changes  after  they  have
occurred, particularly the effects of subtle changes that are
a result of community interactions rather than physiological
responses by one or more major species.  Further research
may identify  critical temperatures or sequences of tem-
perature changes that cannot be exceeded  and may thereby
provide  a  predictive capability as well.  (See Appendix
II B.)

Mixed  Water Body (or major region thereof)
  This  is the region most  commonly considered  in  es-
tablishing water quality standards, for it generally includes
the major area of the water body. Here the results of thermal
additions are observed as small temperature increases over a
large area (instead of high temperatures locally at the dis-
charge point), and all heat sources become integrated into
the normal  annual temperature cycle (Figure III-6 and
Figure III-7 insert).
  Detrimental high temperatures in this  area  (or parts of
it) are defined by the criteria for maximum temperatures
for prolonged exposure  (warm  and cool months) for the
most sensitive species or  life stage occurring there, at each
time of year, and by the  criteria for reproduction.
  For  example,  in the lake  with the hypothetical  power
station, there may be  40 principal fish species, of which half
are considered  important. These species have spawning
temperatures ranging from 5 to 6 C for the  sauger (Stizo-
stedion canadense)  to 26.7 C for the spotted bullhead (Ictalurus
sen acanthus). They also have a similar range of temperatures
required for egg  incubation, and  a  range  of maximum
temperatures  for  prolonged exposures of juveniles and
adults. The requirements, however, may  be met any time
within normal time spans, such as January 1 to 24 for sauger
spawning, and March 25 to  April 29  for smallmouth bass
spawning. Maximum temperatures for prolonged exposures
may  increase steadily  throughout  a spring  period.  To
predict effects of thermal discharges the pertinent tempera-
tures for reproductive activities and maximum temperatures
for each  life stage can be plotted over a  12-month period
such as shown in Fig. Ill—6. A maximum annual tempera-
ture curve can become apparent when sufficient biological
data are available. Mount  (1970)308 gives an  example of
this type of analysis.

Discharge Canal
   Canals  or  embayments  that carry  nearly undiluted
condenser cooling water can develop biological communities
that are atypical of normal seasonal communities. Interest
in these areas does  not generally derive from concern for a
balanced ecosystem, but rather from effects that the altered
communities can have on the entire aquatic ecosystem.
   The general  criteria for  nuisance organisms  may  be
applicable. In the discharge canals of some existing power
stations, extensive mats of temperature-tolerant blue-green
algae grow and  periodically break away, adding a decom-
posing organic matter to the nearby shorelines.
   The winter criterion  for maximum  temperatures  for
prolonged exposures identifies the potential for fish kills due
to rapid decreases in temperature.  During cold seasons
particularly,  fish are  attracted  to  warmer water  of  an
enclosed  area, such as a  discharge canal.  Large numbers
may reside  there for sufficiently long periods to become
metabolically  acclimated to  the warm  water.  For any
acclimation  temperature there  is a minimum temperature
to which the species can be cooled rapidly and still survive
(lower incipient lethal  temperature).  These  numerical
combinations, where  data are  available,  are found  in
Appendix II-C. There would be 50 per cent mortality,  for
example,  if largemouth bass  acclimated  in a discharge
canal to  20 C, were cooled to 5.5 C or below. If normal
winter ambient  temperature is less than 5.5 C,  then the
winter maximum should  be below  20 C,  perhaps nearer
15 C. If it is difficult to maintain the lower temperatures,
fish should be excluded from the area.

                                           TOXIC  SUBSTANCES

   Until  recently,  mercury  most  commonly  entered  the
aquatic environment by leaching from geological formations
and by water  transport to  streams and lakes.  Since  the
industrial revolution, however, increasing amounts of mer-
cury have been added to the  aquatic environment with
waste products from manufacturing processes or through
improper disposal  of industrial and consumer products. In
addition, large quantities of mercury enter the environment
when ores are  smelted to recover such metals as copper,
lead, and zinc  (Klein  1971),343  and when fossil fuels  are
burned. Whereas the maximum amount of mercury released
by weathering  processes is approximately 230 metric tons
per year worldwide, the amount released by  the burning
of coal is on the order of 3000 tons per year; and a further
quantity,  probably comparable  to 3000 tons, is emitted
from industrial  processes (Joensuu 1971).341
   In urban and industrial areas consumer  products con-
taining  mercury are often disposed of in  sewer systems.
These mercury discharges, though individually small, can-
not be considered  insignificant, because cumulatively they
add large quantities of mercury to the water  courses that
receive these effluents. On  the average, the mercury concen-
tration in sewage effluent is one order of magnitude greater
than its concentration  in  the water course  that receives it
(D'ltri unpublished data  1971).359 Based on Klein and Gold-
berg's 1970344 report of mercury concentrations in samples
of ocean sediments near municipal sewer out-falls, it  can
be calculated that in an urban area from 400 to 500 pounds
of mercury per million population are discharged to  re-
ceiving waters every year. The uses of mercury are varied,
and its consumption is fairly large. The National Academy
of Sciences (1969)347 reported the consumption of mercury
by user category.
   World attention focused on the environmental mercury
problem  when human beings  were poisoned by  eating
contaminated fish and shell fish during the middle and late
1950's in  Minamata, Japan. Since the first occurrence of
"Minamata disease"  in  1953,  121  cases resulting in 46
deaths have been confirmed  in the Minamata area with an
additional  47 confirmed  cases  and  6  deaths in  near!
Niigata (Takeuchi 1970).362
  In Sweden  in the 1950's, conservationists charged th
the abundance of methylmercury in the environment w
causing severe poisoning in seed-eating  birds  and  the
predators  (Johnels et al. 1967).342 These poisonings cou
be related  to  the use of methylmercury in  seed dressing
When these seed dressings wen? prohibited, levels of mercu
declined substantially in seed-eating animals. At about tl
same  time, investigators found high  levels  of mercury
fish in waters  off Sweden, practically all of it in the  for
of methylmercury.

Biological Methylation

  Some microbes are capable  of biologically synthesizir
methylmercury from mercury  ions (Jensen  and Jcrneli
1969;339 Wood et al. 1969;368 Dunlap 1971 ;333 Fagerstro
and Jernelov 1971).334 At low concentrations, the forma tic
of dimethylmercury is favored in the methyl transfer reactic
but at higher concentrations of mercury, the major produ
appears to be  monomethylmercury. In any  particular eci
system,  the amounts of mono- and  dimethylmercury  con
pounds are determined by the presence of microbial specie
the amount of organic  pollution loading, the mercury coi
centration, temperature, and pH (Wood et al. 1969).3:>s

Biological Magnification

  Aquatic  organisms concentrate methylmercury in  the
bodies either directly from the water or through the foe
chain (Johnels et al. 1967;:!42 Hannerz 1968,-356  Hasseln
1968,338 Miettinen  et  al.  1970346). Northern  pike  (Est
lucius) and rainbow  trout (Salmo gairdneri) are able to  a
similate and concentrate methylmercury directly into  the
muscle tissues  from ingested food (Miettinen et al. 1970).3
In general, mercury in organisms eaten  by fish increases ;
each trophic level of the food chain (Hamilton 1971).3
The magnitude of the bioaccumulation of mercury is d<
termined  by  the species,  its exposure, feeding  habit
metabolic rate, age and size, quality of the water, and th
degree of mercury  pollution  in  the  water. Rucker  an

                                                                                                Toxic Substances/] 73
Amend (1969)349 established that rainbow trout contained
mercury levels of 4.0  and 17.3 Mg/g  in their muscle and
kidney tissue after being exposed to 60 ng/l of ethylmercury
for one hour a day over 10 days. Fresh water phytoplankton,
macrophytes, and fish are capable of biologically magnifying
mercury concentrations from water 1000 times (Chapman
et al. 1968).33° Johnels et al. (1967)342 reported a mercury
concentration factor from water to pike of 5000 or more.
Johnels et al.  (1967)34'2 had previously shown that  when
mercury levels in pike muscle  were below  0.2  ^g, g, the
level  was relatively constant irrespective of  weight,  but
above 0.2 Mg/g,  the  concentration of mercury  tended to
increase with increasing age and weight.
   Experiments in progress at the National Water Quality
Laboratory  in  Duluth,  Minnesota,  (Mount unpublished
data  1971)361  indicate  that  when brook  trout  (Salvelinus
fontinahf) are held in water containing 0.05 pg/\ of methyl-
mercury for 2 months they  can  accumulate more  than
0.5 /ig'g  of mercury. This  is  a  magnification  of 10,000
times. In the  same experiments, exposure to 0.03  Mg/1 for
5 months resulted in continuing accumulation in fish tissue
with no indication of a plateau.  In a group  of fish held at
one /xg, 1, some organs  contained 30 Mg'g- Some fresh water
invertebrates  have also been reported  to  have a 10,000
magnification (Hannerz 1968).331'
   Although the mechanisms by which mercury accumulates
and  concentrates  have not been fully explained,  at  least
three factors are involved: the metabolic rate of individual
fish;  differences  in the selection of food  as fish  mature;
and the epithelial surface of the fish (Wobeser et al. 1970 ;357
Hannerz  1968).336 The rate at  which fish lose  methyl-
mercury also  has considerable  effect on magnification of
mercury in  the tissues. Miettinen et al. have shown in  a
series of papers (1970)34C that the loss of methylmercury  is
both fast and slow in fishes. The fast loss occurs early, while
mercury is being redistributed through the body, and lasts
only  a  few weeks. The subsequent loss from established
binding sites follows slowly; a  half-life is estimated  to be
on the order of 2 years. These rates mean that fishes, and
perhaps  other lower vertebrates, reduce  their content of
methylmercury many times more slowly than do the higher
terrestrial vertebrates. Man, for  example,  is  usually con-
sidered to excrete half of any given mercury residue in
about 80 days. Extremely low rates of loss have also  been
shown in different species of aquatic mollusks  and crayfish
(Cambarus) (Nelson 1971).348
   Excessive mercury residues in  the sediments are dissipated
only slowly. Lofroth (1970)345 estimated that aquatic habi-
tats polluted with mercury continue to contaminate fish for
as long as 10  to 100 years after pollution has stopped.

Mercury in  Fresh Waters
   Mercury measured  in the water of selected rivers of the
United States ranged from less than 0.1  jtg/1 to  17  ng/L
Two-thirds of the rivers contained 0.1 Mg/1 or less (Wallace
et al. 1971).355 The value of 0.1 /ig/1 is also reported as the
earliest reliable  estimate  of mercury levels in uncontami-
nated  fresh water  (Swedish National  Institute of Public
Health 1971).351 Some rivers tested by the Swedish Institute
were as low as 0.05 Mg/1, which was also the average mercury
level in some salt waters.

Toxicity of Organic Mercury in Water
  The  chemical form of methylmercury administered to
fish  makes little difference in its toxic effect (Miettinen et
al. 1970).346 The methylmercury bound to sulfhydryl groups
of proteins, as it would be in nature, is just as toxic as the
free  unbound ionic form.
  Fish are able  to survive relatively high concentrations of
organomercurials for a short  time with  few ill  effects.  For
example,  fry of steel  head  trout  (Salmo gairdrieri)   and
finger-lings of sockeye salmon (Oncorhynchus nerka) are able
to survive in  10 mg/'l of pyridyl mercuric  acetate for  one
hour with no toxic effects (Rucker and Whipple 1951).350
The LC50 of pyridyl mercuric acetate for some freshwater
fish  ranges from 390 jug/1 to 26,000 /xg/1 for exposures be-
tween  24  and 72 hours  (\Villford 1966;3"6  Clemmens  and
Snced  1958,331 1959).332
  As the exposure times lengthen, lower concentrations of
mercury are  lethal. On the basis of 120-hour bioassay tests
of three species of minnows, Van Horn and Balch (1955)354
determined that the  minimum lethal  concentrations of
pyridyl mercuric acetate,  pyridyl mercuric chloride, phenyl
mercuric acetate,  and ethyl  mercuric phosphate averaged
250  /ig/1.
  Recent experiments at the National Water Quality Lab-
oratory (Mount, personal communication  1971)360 indicated
that 0.2 /ug/1 of methylmercury killed  fathead  minnows
(Ptmephalespromelas) within 6 to 8 weeks.  Toxicity data from
this  same  laboratory on several other  species including
Gammarus,  Daphnia,  top  minnow (Fundulus sp.) and brook
trout (Salvelinus fontmahs) indicated  that none was more
sensitive than the fathead minnow.
  Northern pike seem to be  more sensitive.  When  they
were reared in water containing 0.1 /ig/1 of methylmercury
for a season and then placed in clean water,  they underwent
continuing mortality. Scattered mortality from this source
could  ordinarily not be  detected in nature,  because  the
affected fish became uncoordinated and probably would
have been eaten by predators (Hannerz  1968,33G quoted by
Nelson 1971348).
   Some species of  plankton  are  particularly sensitive.
Studies of the effect of mercury on phytoplankton species
confirmed that concentrations as low as 0.1 /zg/1 of selected
organomercurial fungicides decreased both the photosynthe-
sis  and the  growth of laboratory cultures of the marine
alga Nitzschia delicatissum, as well as of some fresh water
phytoplankton  species (Harriss et  al.  1970).337  Ethyl-
mercury phosphate is lethal  to marine  phytoplankton at
60 Mg/1, and levels as low as 0.5 jig/1 drastically limit their

114/Section III—Freshwater Aquatic Life and Wildlife
growth  (Ukeles  1962).363 There is insufficient information
about the thresholds for chronic toxicity.

Tissue Levels and Toxicity
  There is almost no information on the  concentrations of
mercury in the tissues of aquatic organisms that are likely
to cause mortality of the organisms themselves. Fish  and
shellfish found dead in Minamata contained 9 to 24 /ug/g
of mercury on the usual wet-weight basis;  presumably some
of these  levels were lethal (Nelson  1971).348 Miettinen et al.
(1970)346 showed that pike which  had been experimentally
killed by methylmercury contained from 5 to 9.1 ng/g and
averaged  6.4 and 7.4 micrograms  of methylmercury per
gram of muscle tissue.

Discussion of Proposed Recommendations
  At the present time there are not sufficient data available
to determine the levels  of mercury in water that are safe
for aquatic organisms under chronic exposure. There have
not been, for example,  any experiments  on the effects of
chronic  exposure to  mercury on reproduction and growth
of fish in the laboratory.  Since experiments on sublethal
effects are lacking, the next most useful information is on
lethal effects following moderately long exposures of weeks
or months. The lowest concentration shown to be lethal to
fish is 0.2 /ig/1 of methylmercury which is lethal to fathead
minnows (Pimephalespromelas) in six weeks. Because 0.2  Mg/1
of methylmercury has been shown to be lethal, it is suggested
that this concentration of mercury not be exceeded at any
time or  place in natural waters.  Since phytoplankton are
more sensitive, the average concentration of methylmercury
in water  probably  should  not exceed 0.05 /ug/1  for their
protection. This recommended average  is approximately
equal to the supposed natural  concentrations of mercury
in water; hence little mercury can be added to the aquatic
environment.  The  National Water  Quality  Laboratory
(Mount, unpublished  data 1971)361  found  that exposure of
trout to 0.05 Mg/1 of methylmercury for 3 months resulted
in concentrations of 0.5 ng/g, the Food and Drug Adminis-
tration guideline for the maximum level for edible portions
of fish flesh.
  These concentrations of mercury or methylmercury in
water are very low and difficult to measure or differentiate
without  special  equipment and  preparation.  These low
concentrations can also only be measured as total  mercury.
Since sediments may contain 10,000  times the  amount of
mercury in water, suspended solids in water can seriously
affect the values found  in analyses of water for mercury
(Jernelov 1972).340 Because of these difficulties and because
the real danger of mercury pollution results from a biological
magnification, recommendations  for  mercury residues in
tissues  of aquatic  organisms should be developed.  This
would make monitoring and control not only more effective
and certain  but also more feasible technically.  Unfortu-
nately,  data are not yet available on the residue levels that
are safe  for  the aquatic organisms  themselves  and  fc
organisms higher in the food chain, such as predatory fis
or fish-eating birds. It is known that concentrations of 5 t
10 ng/g are found in some fish that died of methylmercur
poisoning, and that 0.01  to 0.2 ng/g is apparently a usu;
background level in freshwater fish. Because data are lackin
for safe residue levels in aquatic food chains, it is suggeste
that the  Food & Drug Administration guideline level c
0.5 Mg/g of total mercury in edible portions of freshwatc
fish used as human food be the guideline to protect predatoj
in aquatic food chains.
  Hence, mercury residues should not exceed 0.5 ng/g i
any aquatic organisms. If levels approaching this are founc
there should  be  total  elimination of all possible sources c
mercury pollution.
  No distinction has been drawn between organic and ir
organic forms of mercury in these discussions because of th
possibility of  biological transformation to the organic phas
in aquatic habitats. Since  the form of mercury in  watc
cannot be  readily determined,  the recommendations  ar
primarily based upon  methylmercury but expressed as tote

   Selected  species  of fish and  predatory aquati
organisms should be protected when  the followin
conditions  are fulfilled:  (1)  the  concentration  o
total mercury does not exceed a total body burdei
of 0.5 M£/£ wet  weight in any aquatic  organism
(2) the total mercury concentrations in unfilterei
water do  not exceed 0.2  fig/1 at any time or place
and (3) the average total mercury concentration ii
unfiltered water does not exceed 0.05 jug/1-

   The occurrence of dialkyl  phthalate residues has bee
established in various segments of the aquatic environmer
of North America.  Phthalate ester residues occur principall
in samples of water,  sediment,  and aquatic organisms i
industrial and heavily populated areas (Stalling 1972).3'
In fish di-n-butyl phthalate  residues ranged from 0 to 50
fig/kg, and di-2-ethylhexyl phi:halate residues were as hig
as 3,200 Mg/kg.  No well-documented information exists o
the fate of phthalate  compounds in aquatic environment!
   Phthalate  esters are widely used as  plasticizers, particu
larly in  polyvinyl chloride  (PVC)  plastics.  The  mos
common phthalate ester plasticizer is di-2-ethylhexyl phthal
ate. Di-7z-butyl phthalate has been used as an insect repellen
(Frear 1969)362  and  in pesticide formulations to  retari
volatilization (Schoof et al.  1963).365 Production of diocty
phthalate ester placticizers was estimated to  be 4.10Xl08lb
in  1970 (Neelyl 970).363 Total phthalate ester productioi
was reported to be 8.40 X 108 Ibs in 1968, of which 4.40 X 10
Ibs were dioctyl phthalate esters (Nematollahi et al. 1967).36
Production of  phthalic  anhydride was estimated   to  bi

                                                                                                   Toxic Substances/175
7.60X 108 Ibs in 1970 (Ncely 1970).363 PVC plastic formula-
tions may contain 30 to 60  parts per hundred of phthalate
ester plasticizer (Nematollahi et al.  1967).364

  Studies to determine the acute or chronic toxicity effects
of phthalate esters or other plasticizers on aquatic organisms
have only recently been undertaken (Stalling 1972).366 For
example, the acute toxicity of di-«-butyl  phthalate  to fish
is extremely low compared  to pesticides (Table  111-14).
  Daphnia magna were exposed to 0.1 fie;/I of 14C di-rc-butyl
phthalate and the organisms accumulated chemical residues
of 600 /^g/kg within 10 days, or a 6,000-fold magnification
(Saundcrs, unpublished data 1971).367 However, after transfer
of the  Daphnia to uncontaminated  water,  approximately
50 per cent  of the di-rz-butyl phthalate was excreted in three
days. It was recently found that a concentration of 3 jug/1
of di-2-ethylhexyl phthalate significantly reduced  the growth
and  reproduction of Daphnia magna (Sanders  unpublished
data 1971).367
  The acute toxicity of phthalate esters appears  to be rela-
tively insignificant, but  these compounds  may be  detri-
mental to aquatic organisms at low chronic concentrations.

  Until a more detailed  evaluation is made of toxi-
cological effects of phthalate esters on aquatic eco-
systems, a safety factor of 0.1 has been applied to
data for Daphnia magna toxicity, and a  level not
to  exceed   0.3  /*£/! should protect   fish and  their
food supply.


  Polychlorinated biphenyls (PCB) have been found in fish
and wildlife in many parts  of the world and at  levels that
may adversely affect  aquatic  organisms  (Jensen  et  al.
1969;376  Holmes  et  al.  1967;375  Koeman  et al. 1969;378
                                    TABLE 111-14—Acute Toxicity of Di-n-butyl  Phthalate to
                                            Four Species of Fish and Daphnia Magna.
LC50 in jug/I
Species Temperature 24 hr
Fathead minnow (Pimephales promelas)
Bluegill (Lepomis macrechinis) 1230
Channel catfish (Ictalurus punctatus) . 3720
Rainbow trout (Salmo gairdnen)
Daphnia magna
48 hr

96 hr
1300 (Stalling)'"
731 (Stalling)**
2910 (Stalling)'"
6470 (Sanders)1"
>5000 (Sanders)3"
                                    Risebrough et al. 1968).386 The environmental occurrence,
                                    uses, and present toxicological aspects of PCB were recently
                                    reviewed  by  Peakall  and   Lincer  (1970),384  Gustafson
                                    (1970),372 Risebrough  (1970),387 and Reynolds (1971).385
                                      Biphenyls may have  1 to  10 attached  chlorine  atoms,
                                    making  possible over 200 compounds  (Gustafson 1970).372
                                    PCB occur  as residues in fish, and presumably also in water,
                                    as  mixtures of chlorinated  biphenyl  isomers  as shown in
                                    Table 111-15 (Stalling and Johnson, unpublished data 1970,3%
                                    Stalling mpress™2).
                                      Analysis of PCB has been accomplished by gas chromatog-
                                    raphy after separation of PCB from pesticides. A separation
                                    method  has been described by Armour and Burke (1970)369
                                    and modified by Stalling and Huckins (1971).391 A method
                                    using separation on a charcoal column  has shown  good
                                    reproducibility (Frank and Rees, personal communication) .396
                                    No  standardized gas-liquid  chromatography method has
                                    been proposed for the  analysis of mixtures of PCB in en-
                                    vironmental samples.  The solubility of these formulations
                                    in water has not been  precisely determined, but it is in the
                                    range of 100  to 1,000  /ig/1  (Papageorge 1970).383 Since
                                    PCB have  gas chromatographic characteristics similar to
                                    many organochlorine  pesticides,  they can  cause  serious
                                    interference in the  gas chromatographic  determination of
                                    chlorinated insecticides  (Risebrough et al. 1968).386
                                      The Monsanto Company, the sole manufacturer of PCB
      TABLE 111-15—Composition of PCB Residues in Selected Fish Samples from the 1970 National Pesticide Residue
                                                  Monitoring Program
Cape Fear
Lake Ontario
Mernmac  .
Cincinnati, 0.
Cincinnati, 0.
Marietta, 0.
Marietta, 0.
Redwood, Miss.
PoughKeepsie, N.Y.
Natrona, Pa.
Camden, N.J.
Elizabeth Town, N.C.
Port Ontario, N.Y.
Memphis, Tenn.
Lowell, Mass.
Carp Cyprinus carpio
White crappie Poximus annularus
Channel catfish Ictalurus punctatus
Channel catfish
Smallmouth buffalo Ictiobus bubalus
Goldfish Carassius auratus
Walleye Stezostedion vitreum v.
White perch Roccus americanus
Gizzard shad Porosoma cepedianum
White perch
Drum Aplodmotus grunniens
                                                                                  PCB Residue as Aroclor ® type(,*g/g whole body)
lularus 16
unctatus 38
s bubalus 72
im v.
ledianum 19
IS 11




\7(j/Section III—Freshwater Aquatic Life and Wildlife
in the United States (Gustafson 1970),372 markets eight
formulations of chlorinated biphenyls under the trademarks
Aroclor® 1221, 1232, 1242, 1248, 1254, 1260, 1262, and
1268. The last two digits of each formulation designate the
percent chlorine. Aroclor® 1248 and 1254 are produced in
greatest  quantities. They are  used  as dielectric  fluids  in
capacitors  and  in closed-system  heat  exchangers  (Papa-
george 1970).383 Aroclor® 1242 is used as a hydraulic fluid,
and Aroclor ® 1260 as a plasticizer. Chlorinated terphenyls
are marketed under the trademark Aroclor ® 5442 and 5460,
and a mixture of bi-  and terphenyls is designated Aroclor ®
4465. The isomer composition  and chromatographic char-
acteristics of  each formulation  have   been described by
Stalling and Huckins (1971)391  and Bagley et al. (1970)."°
A contaminant of some PCB. especially those manufactured
in Europe, are chlorinated  dibenzofurans (Brungs personal
communication  1972).393 Although  these  byproducts would
appear to be extremely toxic, no data are available on their
toxicity to aquatic life.

Direct Lethal Toxicity
  Studies of toxicity of PCB to aquatic organisms arc limited.
They show  considerable variation of  toxicity  to  different
species, as well as variation with the chlorine content of the
PCB. Nevertheless, some trends in the  toxic characteristics
have become apparent, principally from the work of Mayer
as described below:

    • The higher the per cent chlorine, the lower the ap-
      parent toxicity of PCB  to fish  (Mayer,  in press).3™
      This was found in 15-day intermittent-flow bioassays
      using bluegills (Lepomis macrochmis) and channel cat-
      fish  (Ictalurus  punctatus)  with  Aroclor®  1242, 1248,
       1254. All LC50 values were in  the  range 10 to 300
    • The bluegill/channel catfish  experiments also illus-
      trated  that all LC50 values decreased significantly
      when exposures continued from 15 to 20 days. The
      96-hour LC50 of a  PCB to fish cannot adequately
      measure its lethal toxicity.
    • The same tests showed that the toxicity of Aroclor ®
       1248 doubled when the temperature was raised from
      20 C to 27 C.
  To invertebrates,  Aroclor®  1242 has about  the same
acute toxicity that it has  to fish. In  4-  and 7-day tests
(Saunders,  in press),3*9 it killed Gammarus at 42 /jg/'l and
crayfish (Cambarus) at 30 /ug/1, with values that were similar
to the 15-day LC50  reported for bluegills. However, there
is an extreme  range in the reported short-term lethal levels
of Aroclor®  1254 for invertebrates. Saunders (in press)3*9
reported  a 96-hour LC50 as 80 jig/1 for crayfish and only
3 ng/l for  glass shrimp  (Paleomonetes)   in 7-day tests; and
Duke et  al. (1970)371 reported that as little as 0.94 /ig/1
killed immature pink shrimp (Panaeus duorarum). Part of this
variation is related to exposure  periods in the tests; part
is  no doubt  the variation in species response.  Again thi
emphasizes the point that short-term tests of acute toxicitie
of PCB have serious limitations.
  Marine animals may be more easily killed by PCB thai
freshwater ones (see Section IV). When two cstuarine fishe
(Lagodon rhomboides and Leiostomits xanthurus) were exposei
for 14 to  45 days to  Aroclor ®  1254, mortalities were ob
served at  5 /ug/1 (Hansen, el al. 1971).373 This indicated ,
toxicity about  five times greater  than  summarized abov
for freshwater fish  but about the same as the toxicity for th
marine crustaceans mentioned above.

Feeding Studies
  Dietary exposure to PCB seems  to  be less of a  direc
hazard to  fish than  exposure  in  water.  Coho salmoi
(Oncorhynchus kisutch) fed Aroclor® 1254 in varying amount
up to 14,500 jiig/kg body weight per day accumulated whol
body residues which were  only 0.9 to 0.5 of the level ii
the food after 240 days of dietary exposure. Growth  rate
were not affected. However, all fish exposed to the highes
treatment died after 240 days exposure; and thyroid activit-
was stimulated in all except the  group treated at the lowes
concentration (Mehrle and Grant unpublished data 1971).39
  At  present, evaluation of data from  laboratory expert
ments  indicates that exposures to PCB  in water represent
a greater  hazard to fish than dietary exposures. However
in the  environment, residue accumulation from dietan
sources could  be  more  important,  because PCB have ;
high affinity for sediments, and therefore, they readily ente
food chains  (Duke ct al.  1970;m Nimmo, et  al. 1971).382

Residues  in Tissue
   It is clear that widespread pollution of major waterway
has occurred, and that appreciable PCB residues exist ii
fish. \Vhen  analyses  of 40  fish from  the  1970 Nationa
Pesticide Monitoring Program were made, only one of thi
fish was found to contain less than 1 /ig/g  PCB (Stalling
and  Mayer  1972).39° The 10 highest residue levels in thi
40 selected  fish ranged from 19 pig/g  to 213  jug/g wholi
body weight.
  By contrast,  residues measiured in ocean fish  have beer
generally  below 1  yug/g (Risebrough 1970;387 Jensen, et al
1969).376  Between the ranges  in freshwater fish and thosi
in marine fish are the levels of PCB found in seals (Jenser
et al.  1969;376 Holden 1970),m  and in the eggs of fish
eating birds in North America  (Anderson et al. 1969;36
Mulhern et  al. 1971 ;380 Reynolds 1971).385
   In laboratory experiments. Crustacea exposed  to varyiru
levels of Aroclor® 1254 in the water concentrated the PCI
within  their bodies more  than  20,000 times.  The tissut
residues may  sometimes  reach an  equilibrium, and  ir
Gammarus fasciatus PCB did nol  concentrate beyond 27,00(
times despite an  additional 3-week  exposure  to 1.6 ng/
Aroclor®  (Saunders 1972).38S In contrast, PCB residues ir
crayfish did not reach equilibrium after a 28-day exposure

                                                                                               Toxic Substances/111
PCB concentration factors by two estuarine fishes, Lagondon
rhomboides and Leiostomus xanthurus, were  similar  to  that
described above for crustaceans, i.e., about  10,000 to 50,000
times the exposure levels  in water (Hansen et al.  1971).373
It is important to note that these accumulations  occurred
at water concentrations of  PCB  that killed the fish in 15
to 45 days.
  Also similar were the accumulation  ratios  of  26,000 to
56,000 for bluegills (Lepomis  macrochirus) chronically exposed
to 2 to 15 jug/1 of Aroclor ® 1248 and 1254. Fathead minnows
(Pimeplmles promelas) chronically exposed to Aroclor® 1242
and  1254 for 8  weeks concentrated   PCB  100,000  and
200,000 times the exposure  levels, respectively. Residues of
50 jig/1 (whole body)  resulted from exposure for 8 weeks
to 0.3  Mg'l Aroclor® 1254  (Nebcker et al. 1972).3S1 These
experiments with bluegills also indicated that the maximum
levels of PCB were generally related to the concentration
of PCB in the water (50,000-200,000 times higher) to which
they were exposed (Stalling and Huckins unpublished data

Effects on Reproduction
  PCB residues in salmon  eggs are apparently related to
mortality of eggs. In preliminary investigations in Sweden,
Jensen  and  his associates  (1970)377 reported that when
residues in groups of eggs ranged from 0.4 to 1.9 /ug/g °n
a whole-weight basis (7.7  to 34 jig,'g on a fat basis), related
mortalities ranged from 16 per cent up to 100 per cent.
  PCB concentrations  in the range of  0.5 to 10 /ig/1 in
water interfered with reproduction of several aquatic ani-
mals according to recent work of Nebeker  et al.  (1971).381
About 5 yug  I of Aroclor®  1248 was  the  highest concen-
tration  that did not affect  reproduction of Daphma magna
and  Gammarus pmidohmnaeus. In tests of reproduction by
fathead minnows (Pimephalespromelas) all died when exposed
chronically to greater than 8.3 jig/l  of either Aroclor® 1242
or Aroclor®  1254. Reproduction occurred at and below
5.4 /ng.l Aroclor®  1242, and at and below  1.8 /ig 1 of
Aroclor® 1254.
  The  association  between residue levels  and  biological
effects in  aquatic animals is scarcely known, but the work
of Jensen et  al. (1970)377  suggested that about 0.5 /ig/g of
PCB in whole salmon eggs  might be the threshold for egg
mortality. Such a  level in  eggs would be associated with
levels in general body tissue  (e.g., muscle) of 2.5 to 5.0 jig/g.
The residue in muscle corresponded to the present Food and
Drug Administration level  for allowable levels of PCB in
fish used as human food.  Residues  measured in the survey
by the  1970  National  Pesticide Monitoring Program were
generally above 5 Mg/g-
  Applying a minimal safety factor of  10 for protection of
the affected population, and for protection of other species
higher in the food  chain,  would yield a maximum permis-
sible tissue concentration of 0.5 Mg/g in any aquatic organism
in any habitat affected by PCB.
General Considerations and Further Needs

  Another means of control would be justified  in view of
the toxicity of PCB, the lack of knowledge about how it
first  enters natural  ecosystems as a pollutant, and its ap-
parent distribution in high concentrations  in  freshwater
fish in the United States.  This method would be  to regulate
the manufacture of PCB and maintain close control  of its
uses  to avoid situations where PCB is lost to the  environ-
ment. The Monsanto Company recently restricted the sale
of PCB for uses in which  disposal of the end products could
not be controlled, as with plasticizcrs (Gustafson 1970).372

Basis for Recommendations

  For PCB levels in water, the most sensitive reaction shown
by aquatic organisms is to  the lethal effects of low concen-
trations continually present in water for long periods (weeks
or months). Concentrations in  the range of 1  to 8 /ig/1
have been shown to be lethal to several animals.
  The work of Hansen,  et al. (1971)373  and Stallings and
Huckins  (unpublished dala 1971)391  indicates  that  concen-
trations of 0.01 fig, 1 of PCB in water over periods of up to
36 weeks  could lead to dangerous  levels of PCB in the
tissues of  aquatic  organisms. Accumulation by factors of
75,000 to  200,000 times  is  indicated by  their work. If the
higher ratio is taken, 0.01 /ig/1 in water might result in 2.0
jig, g in flesh on whole fish  basis. This is comparable to the
residue  level  in  salmon eggs  associated with complete
mortality of embryos. Therefore, a concentration is recom-
mended that is reduced by a factor of 5, or 0.002  /ig/1. In
addition, a control based on  residue  levels is required, as
well  as one based on PCB in the water.

  Aquatic life should  be protected where the maxi-
mum concentration  of  total PCB  in unfiltered
water does not exceed 0.002 /tg/1 at  any time or
place, and the residues in the general body tissues
of any aquatic organism do not exceed 0.5 /zg/g.


General Data
  Several reviews of the toxicity of metals are available
(e.g.,  Skidmore   1964;428  McKee   and   Wolf  1963;415
Doudoroff and Katz 1953).406 Some  of  the  most  relevant
research is currently in progress or only recently completed.
Some deals with  chronic effects of metals  on survival,
growth, and reproduction of fish and other organisms. The
completed studies have estimated safe concentrations, and
from these application factors have been  derived as defined
in the discussion of bioassays (pp. 118-123).
  The important relation  between  water  hardness  and
lethal toxicity  is well documented  for  some metals  (see
Figure III-9).  For  copper, the  difference  in toxicity may

178/'Section HI—Freshwater Aquatic Life and Wildlife
                  S   0.5



                                                      50           100          200

                                                           Total Hardness, mg/1 as CaCo^j
                          Brown 1968,401 Lloyd and Herbert I960'
 FIGURE IH-9—The 48-Hour Lethal Concentrations of Three Heavy Metals for Rainbow Trout (Salmo gairdneri). (Simile
                                       Relationships Exist for Other Species of Fish.)

                                                                                           Toxic Substances/179
not be related to the difference in hardness per se, but to
the difference in alkalinity of the water that accompanies
change  in  hardness (Stiff  1971).434 Nevertheless, the re-
lation to hardness is a  convenient and  accepted one. The
hardness classification  developed by the U.S. Geological
Survey  is the following:
  Moderately hard
 0- 60 mg/1 (hardness as CaCO3)
61-120 mg/1
in excess of 120 mg/1
  There  are  many chemical species of metals  in water;
some are toxic to aquatic life, others are not. Hydrogen ion
concentration in water is extremely important in governing
the species and solubility of metals and therefore the lethal
toxicity. At high pH, many heavy metals form hydroxides
or basic carbonates that are relatively insoluble and  tend
to precipitate. They may, however, remain suspended in
the water as fine  particles (O'Connor et al.  1964;421  Stiff
  The  toxicity  of suspended hydroxides of metal depends
on the  particular situation. For example, suspended zinc has
been found to be nontoxic (Sprague 1964a&b),429'430 equally
as toxic as dissolved zinc  (Lloyd I960)412 and more toxic
than dissolved  zinc (Mount 1966).417  This  indicates  that
suspended zinc is at least potentially poisonous, and there-
fore the total metal measured in the water should be  con-
sidered toxic. It is difficult to predict the effect of pH on
toxicity. For example, low pH (about 5) as well as high pH
(about 9) reduced toxicity of copper and zinc compared to
that at neutral pH (Fisheries Research  Board  of Canada
unpublished data  1971).444 Therefore pH should be regulated
in bioassays with metals in order to simulate local conditions
and to explore any effect of local variation of pH.
   In addition to hardness,  numerous other factors influence
the lethal toxicity  of copper  to fish.  McKee and  Wolf
(1963)415 and Doudoroff and Katz (1953)406 included dis-
solved  oxygen, temperature,  turbidity,  carbon dioxide,
magnesium salts, and phosphates as factors affecting copper
toxicity.  Artificial  chelating compounds such as nitrilo-
triacetic acid can  reduce or  eliminate toxic  effects of zinc
and other  metals  (Sprague 1968b)432 and  there may be
natural chelating  agents that  would do the same thing.
Certain organic ligands  (Bender et al.  1970)399 and amino
acids from sewage  treatment plant  effluent (United King-
dom Ministry  of  Technology  1969)435 also  reduce  the
toxicity of copper by forming  copper-organic complexes
that do not contribute to lethal toxicity. It is safe to assume
that some of these factors will influence the toxicity of other
metals. In addition, the amount of metals found (at  least
temporarily) in living biological matter is included in most
routine water analyses. At the  present time, however, it is
not possible to predict accurately the amount of total metal
in any environment that may be lethal,  biologically active,
or  contributory to toxicity. Consequently,  the following
recommendations  are made.
  Since forms or species of metals in water may
change with shifts in the water quality, and since
the  toxicity  to  aquatic  life  may  concurrently
change in as yet unpredictable ways, it is recom-
mended  that water quality criteria for a  given
metal  be based on the  total amount of it in the
water, regardless of the chemical state or form of
the metal, except that settleable solids should be
excluded  from the  analysis (Standard Methods
1971).433 Additionally, hardness affects the toxicity
of many metals (see  Figure III-9).
  Metals  which have collected in  the  sediments
can redissolve into  the water, and such redissolved
metals should meet  the criteria for heavy metals.
To protect aquatic life, amounts likely to be harm-
ful should not occur in the sediments.
  It  is recommended that  any metal species not
specifically mentioned in this report but suspected
of  causing detrimental  effects  on  aquatic life be
examined as outlined in the section on  Bioassays.

  Current  research by  Freeman and Everhart (1971)407
indicated  that  aluminum  salts  were  slightly  soluble at
neutral pH;  0.05  mg/1  dissolved and  had no sublethal
effects on  fish. At pH 9, at  least 5 mg/1  of aluminum dis-
solved and this killed fingerling rainbow trout within 48
hours. However, the suspended precipitate of ionized alumi-
num  is toxic. In most natural waters, the ionized or po-
tentially ionizable aluminum would be in the form of anionic
or neutral precipitates, and anything greater than 0.1 mg/1
of this would be deleterious to growth and survival of fish.

  Careful examination of toxicity problems should
be made to protect  aquatic life in situations where
the  presence  of ionic  aluminum  is  suspected.
Aluminum may have considerably greater toxicity
than has been assumed.

  This metal is  an extremely dangerous cumulative poison.
In mammals (Nilsson  1970),420 fish (Eaton unpublished data
1971),442 and probably  other animals, there is insidious,
progressive, chronic poisoning because there is almost no
excretion of the metal. In its acute lethal action on rainbow
trout (Salmo gairdnen), Ball  (1967)398 found cadmium un-
usually slow. A lethal  threshold of 0.01 mg/1 was not dis-
cernible until  seven  days'  exposure. Other  investigators
(Pickering  and Gast,  in press,'12'1 Eaton unpublished  data
1971)442 have determined lethal threshold concentrations in
fathead minnows in 2 to 6 days and in bluegill in 96 hours.
The  chronically safe  levels  for both fathead minnows

180/Section III—Freshwater Aquatic Life and Wildlife
(Pimephales promelas)  (Pickering and  Gast, in press)**'1 and
bluegill sunfish (Lepomis macrochirus) (Eaton unpublished data
1971)442 in hard water (200 mg/1 as CaCO3) are between
0.06  and 0.03 mg/1. In these exposures, death of eggs or
early larvae was one of the effects observed at the  lowest
unsafe concentrations tested. Recent exposures of eggs and
larvae at the National Water Quality Laboratory (Duluth)
in soft water (45 mg/1 as CaCOs) demonstrated that 0.01
mg/1 was unsafe; 0.004 mg/1 was safe for several warm- and
coldwater fishes, including some  salmonids;  and the safe
level for coho salmon fry  (Oncorhynchus kisutch) was  lower,
i.e.,  between 0.004 mg/1 and 0.001  mg/1  (McKim and
Eaton unpublished data 1971).'145
  Daphnia magna appeared to be very sensitive to cadmium.
Concentrations of 0.0005 mg/1 were found to reduce repro-
duction in  one-generation exposures lasting three  weeks
(Biesinger and Christensen  unpublished data  1971).440 This
sensitivity is probably  representative  of other crustaceans
as well.

  Aquatic life should be protected where  levels of
cadmium do not exceed 0.03  mg/1 in water having
total hardness above 100  mg/1 as CaCO3, or  0.004
mg/1 in waters with  a hardness of 100  mg/1 or
below at any time or  place. Habitats should be
safe for crustaceans or  the eggs and larvae of
salmon  if the levels of cadmium do  not exceed
0.003 mg/1 in hard water or 0.0004 mg/1 in  soft
water at any time or place.

   The chronic toxicity of hexavalent chromium  to fish has
been studied  by Olson  (1958),422 and Olson and  Foster
(1956,423 1957).424  Their data demonstrated  a pronounced
cumulative  toxicity  of chromium  to  rainbow  trout and
chinook salmon (Oncorhynchus tshawy(scha). Duodoroff and
Katz  (1953)406 found  that bluegills  (Lepomis macrochirus)
tolerated a 45 mg/1 level for 20 days in hard water.  Cairns
(1956),403 using chromic oxide  (CrO3), found that a concen-
tration of 104 mg/1 was toxic  to bluegills in  6 to 84 hours.
Bioassays  conducted with four species of fish gave 96-hour
LC50's of hexavalent  chromium thai ranged from  17 to
118  mg/1, indicating  little effect of hardness on toxicity
(Pickering and Henderson  1966).426
   Recently some tests  of chronic effects on reproduction of
fish  have been carried out.  The 96-hour LC50 and safe
concentrations for hexavalent chromium were 33 and 1.0
mg/1  for fathead  minnows  (Pimephales promelas) in  hard
water (Pickering unpublished data 1971),446 50 and 0.6 mg/1
for brook trout (Salvelinus fontinahs) in soft  water, and 69
and  0.3 mg/1 for rainbow trout (Salmo  gairdneri)  in soft
water (Benoit  unpublished data 1971).438 Equivalent values
for  trivalent chromium were little different: 27 mg/1 for
the  96-hour LC50, and  1.0 mg/1 for a safe  concentration
for fathead minnows in hard  water (Pickering unpublishd
data 1971).446
  For Daphnia the LC50 of hexavalent chromium was re
ported as 0.05 mg/1,  and the chronic no-effect  level o
trivalent chromium on reproduction was 0.33  rag/1 (Bie
singer and Christensen unpublished data  1971).44° Some dat;
are available concerning the toxicity of chromium to algae
The  concentrations of chromium that inhibited growth fo
the test organisms are  as follows  (Hervey 1949):410 Chlor
ococcales, 3.2 to  6.4 mg/1;  Euglenoids, 0.32 to 1.6 mg/l
and  diatoms, 0.032 to  0.32  mg/1.  Patrick (unpublished dat
1971)447 found that 50 per cent growth reduction for  twi
diatoms in hard and soft water occurred at 0.2 to 0.4 mg/
  Thus it is  apparent  that there  is a great range  of sensi
tivity to chromium among different  species of organism
and  in different waters. Those lethal levels reported abovi
are 17 to 118 mg/1 for fish, 0.05 mg/1 for invertebrates,  an<
0.032 to 6.4  mg/1 for algae, the highest value being 3,701
times the lowest  one.  The apparent "safe" concentratioi
for fish is moderately high, but the recommended maximun
concentration of  0.05  mg/1 has been  selected in  order ti
protect  other organisms, in particular  Daphnia and certaii
diatoms which are affected at slightly below this concert

   Mixed aquatic populations should be protecte<
where  the concentration of  total  chromium  it
water  does not exceed 0.05  mg/1 at any  time o

   Copper  is known to be particularly toxic to algae  ant
mollusks, and the implications of this should be eonsideree
for any given body of  water. Based on studies of effects o:
these organisms, it is known that the criteria for fish protec
these other forms as well.  Recent work (Biesinger et al
unpublished data 1971)439 indicated that the sale level  o
copper  for reproduction and  growth  of Daphnia  magna  ii
soft  water (45 mg/1  as CaGOs)  is 0.006 mg/1,  which i
similar  to the concentrations described  below as safe fo
fish. The relationship of LC50 to water hardness was showi
in Figure III-7 for rainbow trout (Salmo gairdneri).
   The safe concentration of copper for reproduction by fat
head minnows (Pimephales promelas)  in hard  water  (20(
mg/1 as  CaCOa)  was between  0.015  and 0.033 mg/
(Mount 1968),418 and in  soft  water  (30 mg/1 as CaCO;i
was between 0.011 and 0.018 mg/1 (Mount and Stephat
 1969).419 More recent  work with fathead minnows in hare
water indicated that a concentration of 0.033 mg/1 wouk
probably  be safe  (Brungs unpublished data  1971).441  Ac
ceptable reproduction by brook  trout (Salvelinus fontinalis
in soft water (45 mg/1 as CaCOg) occurred between 0.01(
and 0.018 mg/1 (McKim and Benoit 1971).416 The safe-to

                                                                                            Toxic Substances /181
lethal ratios determined in these studies varied somewhat;
but that for hard water is close to 0.1 and that for soft water
is approximately 0.1 to 0.2. In very soft water, typical of
some northern and mountainous regions, 0.1 of the 96-hour
LC50 for  sensitive species would be  close to what is con-
sidered  a natural concentration in these waters.
  Recent  work indicated that avoidance reactions by fish
may be as restrictive as reproductive requirements or even
more so (Sprague 1964b).430 It has been demonstrated that
Atlantic salmon (Salmo salar) avoid a concentration of 0.004
mg/1 in the laboratory.


  Once a 96-hour LC50 has been determined using
the receiving water in question and the most sensi-
tive important  species in the locality as the test
organism, a concentration of copper safe to aquatic
life in that water can be estimated by multiplying
the  96-hour LC50 by an application factor of 0.1.


  Lead  has a low solubility of 0.5 mg/1 in soft water and
only 0.003 mg/1 in hard water, although higher concen-
trations  of suspended and colloidal lead may  remain in the
water. The extreme effects of water hardness on lead toxicity
are  demonstrated by  the LG50 values in hard and soft
waters.  The 96-hour LC50 values in soft water (20 to 45
mg/1 as CaCO3) were 5 to 7 mg/1 and  4 to 5 mg/1 for the
fathead  minnow (Pimephales promelai) and the brook  trout
(Salvelinusfontinahs) respectively (Pickering and Henderson
1966,426  Benoit  unpublished data 1971).438 Brown  (1968)401
reported a 96-hour LC50 of 1 mg/1  for rainbow  trout
(Salmo  gairdneri) in soft water  (50 mg/1  as CaCOs). (See
Figure III-9 for other values for this species.) The 96-hour
LC50 values  of lead  in  hard water were 482 mg/1 and
442 mg/1  for fathead  minnow and brook trout (Pickering
and Henderson 1966).426
  There is not sufficient information on  chronic toxicity
of lead to fish to justify recommending values as application
factors.  However,  preliminary information  on  long ex-
posures  (2 to 3 months) on rainbow trout and brook  trout
(Everhart  unpublished  data 1971,443 Benoit unpublished data
1971)438 indicated detrimental effects at 0.10 mg/1  of lead
in soft  water (20  to  45 mg/1 as CaCO3), a safe-to-lethal
ratio of less than 0.02.
  Growth of guppies  (Lebistes) was affected  by  1.24  mg/1
of lead  (Crandall  and Goodnight 1962).405 Jones (1939)411
and  Hawksley (1967)408 found chronic  or  sublethal effects
on sticklebacks from  lead  concentrations of 0.1 and 0.3
mg/1. The  conditioned behavior  of  goldfish  (Carassius
auratus)  in a light-dark shuttlebox was adversely affected
by 0.07  mg/1 of lead in soft water (Weir and Hine 1970).437
  Chronic lead toxicity was recently investigated  with
Daphnia magna (Biesinger and Christensen unpublished data
1971)440 and the effect on reproduction was observed at a
level of 0.03 mg/1 of lead. This concentration of 0.03 mg/1,
the safe level for Daphnia, is recommended as the criterion
for protection of aquatic life. It is probably also close to
the safe level  for fish, because  the  tests  described above,
although  somewhat preliminary, indicated that concen-
trations about 2 or  3 times higher had detrimental effects.


   The concentration of lead in water should not
be higher than 0.03 mg/1 at any time or place in
order to  protect aquatic life.


   Most data about mercury involve the organic compounds
(see the discussion  of Organic Mercury, p. 172.)  Infor-
mation is  available,  however, for inorganic mercury in the
form of mercuric ions. Short-term 96-hour bioassay studies
indicated  that  concentrations of 1 mg/1 are fatal to  fish
(Boetius I960,400 Jones  1939,411 Weir and  Hine 1970).«7
For long-term exposures of  10 days or more, mercury levels
as low as  10 to 20 mg/1 have been shown to be fatal to fish
(Uspenskaya  1946).436

   In protecting aquatic life, the recommendations
for organic mercury (p, 174) also pertain here.

   The 96-hour LC50  of  nickel  for fathead  minnows
(Pimephales promelas) ranges from 5 mg/1  in soft water (20
mg/1 as CaCOa) to 43 mg/1 in  hard  water (360  mg/1 as
CaCO3) under static test conditions (Pickering and Hender-
son 1966).426 In water of 200 mg/1 hardness (as GaCO3),
the 96-hour LC50 for fathead minnows was 26 to 31 mg/1
with a chronically safe concentration between 0.8 and 0.4
mg/1  (Pickering unpublished data  1971).446 On the basis of
this work, an application  factor of 0.02 appeared to  be
appropriate for the protection of fish. If this factor is used,
the estimated  safe  concentration  of nickel for  fathead
minnows  in  soft water would  be about  0.1 mg/1.  Using
static test conditions  and  Daphnia  magna,  Biesinger and
Christensen  (unpublished data 1971)440 determined  that  a
nickel concentration of 0.095 mg/1 reduced reproduction
during a 3-week exposure in soft water (45 mg/1 as CaCOs),
and  a nickel concentration of 0.030 mg/1  had no effect.
This result indicated that  the sensitivity of Daphnia magna
is comparable  to that of fish.

   Once a 96-hour LC50 has been determined using
the receiving water in question and the most sensi-
tive important species  in the  locality as the test
organism, a concentration of nickel safe to aquatic

 182/Section HI—Freshwater Aquatic Life and Wildlife
life in that water can be estimated by multiplying
the 96-hour LC50 by an application factor of 0.02.


  The acute lethal toxicity of zinc is greatly affected by
water hardness (see Figure III-7). Pickering and Henderson
(1966)426 determined the  96-hour LC50 of zinc  for fathead
minnows (Pimephales promelas) and bluegills (Lepomis macro-
chirus) using static test conditions. For fathead minnows in
soft water (20 mg/1 as CaCO3) the LC50  was  0.87 mg/1,
and in hard  water  (360 mg/1 as CaCO3) it was 33 mg/1.
Bluegills  were more resistant in both waters. Similarly the
lethal threshold concentration was 3 or 4 times as high for
coarse fish as for trout (Salvelinusfontinalis) (Ball 1967).398
  The 24-hour  LC50 of zinc for rainbow trout  (Salmo
gairdnen) was reduced only 20 per cent when the fish were
forced to swim at 85 per cent of their maximum sustained
swimming speed (Herbert and Shurben 1964).409 The maxi-
mum effect of a reduction in dissolved oxygen from 6 to 7
mg/1 to 2 mg/1 on the acute toxicity of zinc was a 50 per cent
increase (Lloyd 1961,413 Cairns and Scheier 1958,404 Picker-
ing 1968).42S The effects  are  small in comparison to the
difference between  acutely  toxic and  safe concentrations.
The  recommended application  factor  recognizes  these
  A chronic test in  hard water  (200 mg/1 as  CaCOa),
involving fathead minnow  reproduction,  determined the
safe concentration of zinc to be between 0.03 mg/1, which
had no effect, and 0.18 mg/1, which caused 83 per cent
reduction in  fecundity (Brungs 1969).402 Using the 96-hour
LC50 of 9.2  mg/1, the ratio of the above no-effect concen-
tration to the LC50 is 0.0034. Interpolation suggests that
about 0.005 of the LC50 would cause 20 per cent reduction
of fecundity,  making the best estimate  of a valid application
factor close to 0.005.
  There was a reduction in reproduction of Daphma magna
at a zinc concentration of 0.10 mg/1 using soft water (45
mg/1 as CaCOs)  (Biesinger and Christensen unpublished data
1971).440 No  effect was observed at 0.07 mg/1,  which indi-
cated that Daphma magna was  more resistant to zinc  than
the fathead minnow.
  Avoidance reactions by rainbow trout in the laboratory
have  been caused  by 0.01 of the LC50 of zinc  (Sprague


  Once a 96-hour LC50 has been determined using
the receiving water in question and the most sensi-
tive  important species in  the locality as the test
organism,  a concentration of zinc safe to aquatic
life in that water can be estimated by multiplying
the 96-hour LC50 by an application factor of 0.005.

  Pesticides are chemicals, natural and synthetic, used tc
control or destroy plant and animal life considered adverse
to human society.  Since the  1940's a  large number o
synthetic  organic  compounds  have  been developed foi
pesticide purposes. Presently there are thousands of regis
tered formulations incorporating nearly 900 different chemi
cals. Trends in  production and use of pesticides indicate ar
annual increase of about 15 per cent, and there are pre-
dictions of increased demand during the next decade (Mral
1969).477 The subject of pesticides and their environmenta
significance has been  carefully  evaluated  in the Report o
the  Secretary's  Commission on Pesticides and  their  Re-
lationship to Environmental Health (Mrak 1969).477

Methods, Rale, and Frequency of Application
  Pesticides are used for a wide variety  of purposes in i
multitude  of  environmental  situations.  Often  they arc
categorized according to their use or intended target  (e.g.
insecticide,  herbicide,  fungicide),  but their release in the
environment presents  an inherent hazard to many  non-
target organisms. Some  degree of contamination and risk
is assumed with nearly all pesticide use. The risk to aquatic
ecosystems depends upon the chemical and  physical prop-
erties of the pesticide,  type of formulation, frequency, rate
and methods of application, and the nature of the receiving
  The pesticides of greatest concern are those that are
persistent for long periods and  accumulate in the environ-
ment ; those that are highly toxic to man, fish, and wildlife;
and those that are used in large" volumes over broad areas.
A list of such chemicals recommended for monitoring in the
environment appears in Appendix II-F. The majority of
ihese compounds are  either insecticides or herbicides used
extensively in  agriculture, public health,  and for household
or garden purposes. In  the absence of definitive data on
their individual behavior and their individual effect on the
environment,  some generalization about pesticides is re-
quired to serve as a guideline for establishing water quality
criteria to protect aquatic life. In specific instances,  how-
ever, each compound  must be considered individually on
the  basis of information about its reaction in the environ-
ment and its effect on aquatic organisms.

Sources  and Distribution

  The major sources of pesticides in water are runoff from
treated  lands,  industrial discharges, and  domestic sewage.
Significant  contributions may also  occur in fallout from
atmospheric drift and in precipitation (Tarrant and Tatton
1968).485 Applications  to water  surfaces,  intentional or
otherwise, will result in rapid and extensive contamination.
The persistent organochlorine pesticides have received the
greatest  attention in  monitoring programs (Lichtenberg
et al.  1970,471  Henderson et al. 1969).461 Their extensive

                                                                                                Toxic Substances/ \ 83
distribution in  aquatic  systems  is  indicative of environ-
mental loading from both point and nonpoint sources.
  Many pesticides have a low water solubility that favors
their rapid sorption on suspended or sedimented materials
and  their affinity to  plant and  animal lipids. Soluble or
dispersed fractions of pesticides in the water rapidly decline
after initial contamination, resulting in increased concen-
trations  in the  sediments  (Yule  and Tomlin 1971).489 In
streams,  much of the residue is in continuous transport on
suspended  paniculate  material  or  in  sediments  (Zabik
1969).4W The  distribution within the stream flow is  non-
uniform  because of unequal velocity and  unequal distri-
bution of suspended materials within the stream bed (Feltz
ct al.  1971).454  Seasonal  fluctuations  in  runoff and use
pattern cause  major changes in  concentration during the
year,  but the continuous  downstream transport tends to
reduce levels in  the upper reaches of streams while increas-
ing them in the  downstream areas and eventually in major
receiving basins (i.e.,  lakes, reservoirs,  or  estuaries). If
applications in a watershed cease entirely, residues in the
stream will gradually  and  continuously decline (Sprague
et al.  1971).484 A similar decline would be expected in the
receiving basins  but at a slower rate.
  In lakes the sediments apparently act as a reservoir  from
which  the  pesticide is partitioned  into  the water phase
according to the solubility of the compound, the concen-
tration in the sediment, and the type of sediment (Hamelink
et ;iJ. 1971).158 Dissolved natural organic  materials in the
water may  greatly enhance the water solubility of some
pesticides (Wershaw  et  al.  1969).ls7 Some  investigations
indicated pesticides may  be less  available to the water in
eutrophic systems where the higher organic content in the
sediments has  a  greater capacity to hold pesticide residues
(Lotse et al.  1968,172  Hartung 1970"'°). This in part ex-
plained the difference  in  time required for some waters to
"detoxify,"  as observed in lakes treated with toxaphene to
eradicate undesirable fish species (Terriere et al. 1966).486
  Herbicides  applied  to aquatic systems to  control plant
growths  are removed from  the water by absorption in the
plants or sorption to the hydrosoil. The rate of disappearance
from the water may be dependent upon the availability of
suitable  sorption sites. Frank and  Comes (1967)155 found
residues of dichlobenil  in soil and water up  to  160 clays after
application. They  also found  that cliquat  and paraquat
residues  were  persistent  in  hydrosoils for approximately 3
to 6 months  after application. Granular  herbicide  treat-
ments made on a volume basis deposit greater quantities on
the hydrosoil in deep water areas than in water of less depth.
The granules  may supply  herbicide to the  water  over a
period of time depending upon solubility of the herbicide,
concentrations in the granule, and other conditions.
  Because  the  distribution of pesticides   is nonuniform,
sampling methods and frequency, as well as selection of
sampling sites,  must  be  scientifically determined (Feltz
et al. 1971).454 Pesticides found in the water in suspended
particulate material  and  in  sediments may  be toxic  to
aquatic organisms or contribute to residue accumulation
in them.

Persistence and Biological Accumulation
  All organic pesticides are subject to metabolic and non-
metabolic degradation in  the environment. Specific com-
pounds vary  widely in their rate of degradation, and some
form degradation products that may be both persistent and
toxic. Most pesticides are readily degraded to nontoxic or
elementary materials within a few days to a few months;
these  compounds may be absorbed by aquatic organisms,
but the residues do not necessarily accumulate or persist
for long periods. Concentrations in the organism  may  be
higher than ambient  water levels, but they rapidly decline
as water concentrations are diminished. Examples of such
dynamic exchange have been demonstrated with malathion
(Bender 1969),448 methoxychlor (Burdick  et  al. 1968),449
and various  herbicides (Mullison 1970).478 If degradation
in water is completed within sufficient time to prevent toxic
or adverse physiological effects, these  nonpersistcnt com-
pounds do not  pose  a long-term hazard to aquatic life.
However, degradation rates of specific pesticides are often
dependent upon environmental conditions.  Considerable
variation in persistence may be observed in waters of differ-
ent types.  Gakstatter and Weiss (1965),456  for example,
have shown that wide variations in the stability of organic
phosphorous  insecticides  in  water solutions  is dependent
upon  the  pH of the water. The  half-life of malathion was
reduced from about six months at pH 6 to only one to two
weeks at pH 8. Repeated applications and slow degradation
rates may maintain elevated environmental concentrations,
but there is  no indication that  these  compounds can  be
accumulated  through the food chain.
   Some  pesticides,   primarily  the  organochlorine  com-
pounds,  are  extremely stable,  degrading  only slowly  or
forming persistent degradation products. Aquatic organisms
may accumulate these compounds directly by absorption
from  water and by  eating contaminated  food organisms.
In waters containing  very  low concentrations of pesticides,
fish probably obtain  the greatest amount of residue from
contaminated foods;  but the amount retained in the tissue
appears to be a function  of the  pesticide concentration in
the water and its rate of elimination  from the organism
(Hamelink et al.  1971).4"'8 The  transfer  of residues from
prey to predator in  the food  chain ultimately results  in
residues in the higher trophic levels many  thousand times
higher  than  ambient water levels. Examples of trophic
accumulation have been described in  several locations in-
cluding Clear Lake, California (Hunt and Bischoff I960),463
and Lake Poinsett, South Dakota (Hannon et al. 1970).459

   Samples of wild fish have often contained pesticide resi-
dues in greater concentrations  than  are  tolerated in any

184/Section III—Freshwater Aquatic Life and Wildlife
commercially produced agricultural products.  The highest
concentrations are  often found in the  most highly prized
fish. Coho salmon (Oncorhyncus kisulcK) from Lake Michigan
are not considered acceptable for sale in interstate commerce
on  the  basis  of an interim guideline  for DDT  and  its
metabolites set for fish by the U.S. Food and Drug Adminis-
tration  (Mount 1968).476 Lake  trout (Salvelinus namaycush)
and some catches of chubs (Coregonus kiyi and Coregonus hoyi)
and lake herring (Coregonus artedt) from Lake Michigan also
exceed  the guideline limits and  are thus not considered
acceptable for interstate commerce (Reinert 1970;481 Michi-
gan Department of Agriculture  personal  communication).^
Pesticide residues in  fish or fish products may enter the
human  food  chain  indirectly in other  ways, as in fish  oil
and meal used in domestic animal feeds.
  Fish may survive relatively  high residue concentrations
in their body fats, but residues concentrated in the eggs of
mature  fish may be  lethal to the developing fry.  Up to
100 per cent loss  of lake  trout  (Salvelinus namaycush) fry
occurred when residues of DDT-DDD in the eggs exceeded
4.75 mg/kg  (Burdick  et al. 1964).46° A similar mortality
was reported in coho salmon fry from  Lake Michigan
where eggs  contained significant quantities of DDT, di-
eldrin, and polychlorinated biphenyls (Johnson and  Pecor
1969 ;468 Johnson 1968).«6 Johnson (1967)467 reported that
adult fish not harmed by low concentrations  of endrin in
water accumulated levels in the eggs that were  lethal  to the
developing fry.  Residues in fish may be  directly harmful
under stress conditions or at different temperature regimes.
Brook trout  (Salvelinus fontmalis)  fed DDT at 3.0  mg/kg
body weight per week for  26 weeks suffered 96.2 per cent
mortality during a  period of reduced feeding and declining
water  temperature. Mortality of untreated  control fish
during  the same period was 1.2  per cent (Macek 1968).473
Declining water temperature during the fall was believed
to cause delayed mortality  of salmon parr in  streams con-
taminated with DDT (Elson 1967).453
  In addition to the problem of pesticide residues in aquatic
systems, other problems suggest themselves and remain to
be  investigated, including  the potential  of  resistant fish
species  to  accumulate levels  hazardous  to other  species
(Rosato and Ferguson 1968) ;482 the potential for enhanced
residue  storage when  fish are exposed to more than one
compound (Mayer et al. 1970) ;474 and the potential effect
of metabolites not  presently identified. The adverse  effects
of  DDT on  the reproductive  performance of fish-eating
birds has been well  documented.  (See the  discussion of
Wildlife, pp. 194-198.)
  Levels of persistent pesticides in water that will not result
in undesirable effects cannot be determined on the basis of
present knowledge. Water concentrations below the practical
limits of detection have resulted in unacceptable residues in
fish for  human consumption and have affected  reproduction
and survival  of aquatic life. Criteria  based upon residue
concentrations in  the  tissues of selected species may offe
some  guidance. Tolerance levels for pesticides in wild fisl
have not been established, but action levels have been sug
gested by the  U.S. Food and Drug Administration (Mouri
1968).476 However, acceptable concentrations of persisten
pesticides that offer protection to aquatic life and humai
health are unknown.
  It should also  be  recognized that residue criteria an
probably  unacceptable except on a total ecosystem  basis
Residues  in stream fish  may meet  some  guidelines, bu
pesticides from that stream may eventually create excessiv<
residues in fish  in the downstream receiving basins.  LInti
more is known of the effects of persistent pesticide  residues
any accumulation must be considered undesirable.

  Concentrations of pesticides I hat are lethal to aquatic lif(
have often occurred in local areas where applications overlap
streams or lakes, in streams receiving runoff from recentl)
treated areas, and where  misuse or spillage has occurred
Applications  of pesticides to  water to  control   noxiou;
alants, fish, or insects have  also killed  desirable  species
Fish populations,  however, usually recovered within  a few
months to a year  (Elson  1967).453 The recovery of aquatic
invertebrates  in areas  that have been heavily contaminated
may require a longer period,  with some species requiring
several years  to regain precontamination numbers (Cope
1961,451 Ide 1967).465 Undesirable species of insects may be
ihe first to repopulate the area  (Hynes  1961),464 and  in
some instances the species composition has been completely
changed (Hopkins et  al.  1966).462 Areas that are contami-
nated by pesticide application are subject to loss of fish
populations and reduced food for fish growth  (Schoenthal
]  964,483 Kerswill and Edwards 1967).469 Where  residues are
persistent in  bottom  sediments  for long  periods,  benthic
organisms may be damaged even  though  water  concen-
trations remain low (Wilson and Bond 1969).488
  Pesticides  are toxic to aquatic life over wide ranges.
Great differences  in  susceptibility to  different compounds
exist  between species and  within  species.  For example,
96-hour LC50 values of 5 to  610,000 /ig/1 were  reported
for various fish species exposed to organophosphate  pesti-
cides  (Pickering et al.  1962).*79  In  addition  to species'
cifferences, the toxicity may be modified by differences in
formulation, environmental conditions, animal size and age,
and physiological condition. The effect of combinations of
pesticides on  aquatic  organisms has not received  sufficient
attention.  Macek (unpublished data 1971)491 reported that
combinations of various common pesticides were synergistic
in their action on  bluegill  (Lepomis macrochirus) and rainbow
trout  (Salmo  gairdnen), while  others  had additive effects.
Several of the combinations that were found to be syner-
gistic  are recommended  for  insect  pest  control (Table

                                                                                                Toxic Substances/185
    TABLE 111-16—Acute Toxic Interaction of Pesticide
      Combinations to Rainbow Trout and Bluegills.
Pesticide combination
Compound A
". .
Methyl parathion
Bidrm .
Compound B
Copper sulfate
Copper sultate
Copper sullate
Toxic interaction
 " This combination recommended lor control of insect pests by the U.S. Department of Agriculture.
 Note: mention of trade names does not constitute endorsement.
  Most data on pesticide effects on aquatic life are limited
to a  few species  and  concentrations  that are lethal  in
short-term tests. The few  chronic tests  conducted  with
aquatic species indicated that toxic effects occurred at much
lower concentrations. Mount and Stephan  (1967)475 found
the 96-hour LC50 for fathead minnows (Pimephales promelas)
in malathion was 9,000 jug/1, but spinal deformities in adult
fish occurred during a  10-month exposure  to  580 /ig/1.
Eaton  (1970)452 found  that  bluegill  suffered  the same
crippling effects after chronic exposure to 7.4 /ug/1 malathion
and the 96-hour LC50 was  108 yug/1.
  Where chronic toxicity data are available, they may  be
used to develop application factors to estimate safe levels.
Mount and  Stephan  (1967)475 have  suggested using  an
application  factor consisting of the laboratory-determined
maximum  concentration that  has  no  effect on chronic
exposure divided by the  96-hour LC50. Using this method,
Eaton (1970)452 showed that application factors for bluegill
and  fathead minnow exposed to malathion were  similar
despite a greater than  50-fold  difference  in species sensi-
tivity.  Application factors derived for one compound may
be appropriate  for  closely related compounds that  have a
similar mode of action,  but  additional research is necessary
to verify this concept.  In the absence of chronic toxicity
data, the application factors for many compounds must be
arbitrary values set with the  intention of providing some
margin of safety for sensitive  species,  prolonged exposure,
and potential effects of interaction with other compounds.

Basis for Criteria

  The reported acute toxicity values  and subacute effects
of pesticides for aquatic life are listed in Appendix  II-D.
The acute  toxicity values  multiplied by  the appropriate
application  factor provided the recommended criteria. The
96-hour LC50 should be multiplied by an application factor
of 0.01 in most cases. The value derived from multiplying
the 96-hour LC50  by a factor of 0.01 can be used as the
24-hour average concentration.
  Recommended concentrations of pesticides may be below
those presently detectable without additional extraction and
concentration techniques.  However,  concentrations  below
those detectable by routine techniques are known to cause
detrimental  effects  to aquatic  organisms  and to  man.
Therefore,   recommendations  are based on bioassay pro-
cedures and the use of an appropriate application factor.
  The recommendations are based upon the most sensitive
species. Permissible concentrations in water have been sug-
gested only  where several animal species have been tested.
Where toxicity data arc not available, acute toxicity bio-
assays should be conducted with locally important sensitive
aquatic species, and safe levels should be estimated by using
an application factor of 0.01.
  Some  organochlorine pesticides  (i.e., DDT  including
DDD and DDE, aldrin, dieldrin, endrin, chlordane, hepta-
chlor, toxaphene, lindane, endosulfan, and benzene hexa-
chloride) are considered especially hazardous because of
their persistence and accumulation in aquatic organisms.
These compounds,  including some of their metabolites, are
directly toxic to various aquatic species at concentrations
of less than one /xg/1. Their accumulation in aquatic systems
presents a hazard,  both real  and potential, to animals in
the higher trophic levels, including man (Pimentel  1971,480
Mrak 1969,477 Kraybill 1969,470 Gillett  1969).457  Present
knowledge  is not yet sufficient to predict or estimate safe
concentrations of these compounds in aquatic systems. How-
ever, residue concentrations in aquatic organisms provide a
measure of  environmental contamination. Therefore, spe-
cific  maximum tissue  concentrations have  been  recom-
mended as a guideline for  water quality control.


  Organochlorine Insecticides  The recommenda-
tions for  selected organochlorine insecticides are
based upon levels in water and residue concentra-
tions in whole fish on a wet weight basis. Aquatic
life should be protected where the maximum con-

 186/Section HI—Freshwater Aquatic Life and Wildlife
centration of  the  organochlorine pesticide in the
water  does not exceed  the  values listed in Table
   For  the  protection of  predators,  the  following
values are suggested for residues in whole fish (wet
weight): DDT  (including  DDD  and  DDE)—1.0
mg/kg;  aldrin, dieldrin, endrin, heptachlor  (in-
cluding  heptachlor  epoxide), chlordane,  lindane,
benzene   hexachloride,   toxaphene,   and   endo-
sulfan—0.1 mg/kg, either singly or in combination.
For further discussion, see the section on Wildlife
(P. 197).
   If fish and wildlife are to be protected, and where
residues exceed the recommended concentrations,
pesticide use should be restricted  until the  recom-
mended concentrations are reached  (except where
a  substitute  pesticide will not  protect  human
   Other pesticides  The recommended maximum
concentrations of pesticides in freshwater are listed
in Table 111-18  except that where  pesticides  are
applied  to water to  kill  undesirable aquatic life,
the values will be higher. In the latter instances,
care should  be taken to  avoid  indiscriminate  use
and  to  insure that application  of  the pesticide
follows the prescribed methods.


   Ammonia is discharged  from a wide  variety of industrial
processes and cleaning operations that use ammonia  or
ammonia salts.  Ammonia also results  from the decompo-
sition of organic  matter.
   Ammonia  gas is  soluble  in  water  in the form of  am-
monium hydroxide to the extent of 100,000 mg/'l  at 20  C.
Ammonium hydroxide dissociates readily  into  ammonium
TABLE HI-17—Recommended Maximum Concentrations of
  Organochlorine Pesticides in Whole (Unfiltered)  Water,
           Sampled at Any Time and Any Place.*
TABLE 111-18—Recommended Maximum Concentrations of
Other  Pesticides in Whole (Vnfiltered)  Water, Sampled at
                Any Time and Any Place.*
Organochlorine pesticides
Methoxychlor .
Recommended maximum concentration (ug 1)
0 006
0 005
0 04
        Organophosphate insecticides
E till on
Methyl Parathioit
Cxydemeton methyl
          Carbamate insecticides
      Herbicides, fungicides and defoliants
  • Concentrations were determined by multiplying the acute toxicity values lor the more sensitive species (Appendix
 II-D) by an application factor of 0.01 except where an experimentally derived application factor is indicated.
Dmitrobutyl phenol
2 4-D (PBBE)
2 4-D (BEE)
2 4-D (IDE)
2 4-D (Diethylamine salts)
Eidothal (Disodium salt)
Eidottiat (Oiootassium salt)
Fimac (Sodium salt)
Hidrothal plus
Recommended maximum concentration (Mg/l)

           0 001
           0 02
           0 006
           0 008
           0 004
           0 03
           0 002

Recommended maximum concentrations (jug/l)


Recommended maximum concentrations (ug/l)
           0 2

                                                                                               Toxic Sub stances/187
                TABLE 111-18—Continued
TABLE III-19—Sublethat and Acutely Toxic Concentrations
     of Vn-Ionized Ammonia for Various Fish Species'
nciuiRUtiS, limgluuB aim umuiidiua

Silvex (PGBE)
Silvex (IOE)
Silvex (Potassium salt)

Allethrin .

imbunmiGiiuvii maximum vuiiiiGiiuauiiii w \j


Recommended maximum concentrations (Mg/l)

« Concentrations were determined by multiplying the acute toxicity values for the more sensitive species (Ap-


Striped bass (Marone saxatalis)
Rainbow trout
Perch (Perca)
Roach (Hesperoleucus)
Rudd (Scardinius)
Bream (Lepomis)
Rainbow trout
Rainbow trout
Atlantic salmon (Salmo salar)
Rainbow trout
Chinook salmon (Oncorhynchus

IC50 (rag/I)


No sublethal
effect (mj/l) Author

Hazel etal. (1971)™
0.046 Lloyd and Orr (1969)™
. Ball(1967)«M
" .
Lloyd and Herbert (1960)™
Herbert and Shurben (1965)™
<0.27 Reichenbach-Klinke (1967)*w
<0.006 Burrows (1964)<»s

pendix II-D) by an application factor of 0.01 except where an experimentally derived application factor is indicated.
6 Insufficient data to determine safe concentrations.

n Tn Inrltra * hiah laual nf nrnfaAtlnl
1 fha mnan nt tha C
IR.hnnr 1 pitf'e mac ncpri AC a ha» and an annliralinn far
and hydroxyl ions as follows:


The equilibrium  of the  reaction is dependent  upon  pH,
and within the pH range of most natural waters ammonium
ions predominate (Figure 111-10).  Since the toxic com-
ponent  of ammonia solutions is the un-ionized  ammonia,
toxicity of ammonia solutions increases with increased pH
(Ellis 1937,497 Wuhrmann et  al. 1947,608 Wuhrmann  and
Woker 1948,609 Downing and Merkens 1955496).
  Wuhrmann (1952),607  Downing and Merkens (1955),496
and Merkens and Downing (1957)605 found that  a decrease
in dissolved oxygen concentration increased the  toxicity of
un-ionized ammonia to several species of freshwater fishes.
Lloyd  (1961)502 showed that the increase in  toxicity of
un-ionized ammonia to rainbow trout (Salmo gairdneri) with
decreased oxygen was considerably more severe than for
zinc, copper, lead, or phenol.
  Much of the data  on ammonia  toxicity is not useable,
because reporting of chemical conditions or experimental
control  was  unsatisfactory. Ellis  (1937)497 reported  that
total ammonia nitrogen  concentrations of 2.5 mg/1 in the
pH range of 7.4 to 8.5 were harmful to several fish  species,
but  concentrations of 1.5 mg/1 were  not. Most  streams
without a source of pollution contained  considerably less
than  1  mg/1 total ammonia. The sublethal and  acutely
toxic concentrations of un-ionized ammonia for various fish
species are given  in Table 111-19.
  Brockway (1950)494 found impairment of oxygen-carrying
capacity of the blood of trout at a total ammonia nitrogen
concentration of  0.3 mg/1. Fromm  (1970)499 found that at
total ammonia nitrogen concentrations of 5 mg/1, ammonia
excretion by rainbow trout (Salmo gairdneri) was inhibited;
at 3 mg/1 the trout became hyperexcitable; and at 8 mg/1
(approximately 1 mg/1 un-ionized  ammonia) 50 per cent
                                                          tor ol 0.05 applied to arrive at an acceptable level for most species in fresh water. Two apparently resistant species
                                                          were omitted because they were far out of line with the others. After application of the factor, the resultant level is
                                                          approximately half that projected from the data of Lloyd and Orr (1969).r"!3
were dead in 24 hours (Fromm 1970).4" Goldfish (Carassius
auratus) were more tolerant; at 40 mg/1  of total ammonia
nitrogen, 10 per cent were dead in 24 hours.
  Burrows (1964)495 found progressive gill hyperplasia in
fingerling chinook salmon (Oncorhynchus tshawytscha) during
a six-week exposure to the lowest  concentration applied,
0.006  mg/1  un-ionized  ammonia.  Reichenbach-Klinke
(1967)506 also noted gill hyperplasia, as well as pathology of
the liver and blood, of various species at un-ionized  am-
monia  concentrations  of  0.27  mg/1. Exposure  of carp
(Cyprinus carpio) to sublethal un-ionized ammonia concen-
trations in the range of 0.11 to 0.34 mg/1 resulted  in ex-
tensive necrotic changes and tissue disintegration in various
organs (Flis 1968).498
  Lloyd and Orr (1969)503 found that volume of urine pro-
duction increased with exposure to increasing  ammonia
concentrations, but that an ammonia  concentration of 12
per cent of the lethal  threshold  concentration resulted in
no  increased production  of urine.  This  concentration of
un-ionized ammonia was 0.046 mg/1 for the rainbow trout
used in the experiments.

Recommendation -
  Once a 96-hour LC50 has been determined using
the receiving water in question and the most sensi-
tive important  species in the  locality as the test
organism, a concentration of un-ionized ammonia
(NH3) safe to aquatic life in that water can be esti-
mated by multiplying the 96-hr LC50 by an appli-
cation factor of 0.05; but no  concentration greater
than  0.02  mg/1 is recommended at any  time  or

188/Section III—Freshwater Aquatic Life and Wildlife
                         50 0
                             7 0

  FIGURE 111-10—Percentage of Vn-ionized Ammonia in Ammonium Hydroxide Solutions at 20 C and Various Levels of pi

                                                                                              Toxic Substances/189

   Chlorine and chloramines are widely used in treatment of
 potable water supplies and sewage-treatment-plant effluents,
 and in  power plants, textile and paper  mills,  and certain
 other industries.  Field tests conducted  on caged fish in
 streams below a sewage outfall where chlorinated and non-
 chlorinated effluents were  discharged showed that  toxic
 conditions occurred for rainbow trout (Salmo gandnert) 0.8
 miles below  the  plant  discharge point  when  chlorinated
 effluents were discharged (Basch et al. 1971).M1 It has also
 been shown  that total numbers of fish and  numbers of
 species  were drastically reduced  below industrial  plants
 discharging  chlorinated  sewage effluents  (Tsai  1968,617
   The  toxicity to  aquatic  life of  chlorine in water  will
 depend upon the  concentration of residual  chlorine re-
 maining and  the relative amounts of free chlorine and chlor-
 amines. Since addition of chlorine or hypochlorites to water
 containing nitrogenous materials rapidly forms chloramines,
 problems of toxicity in most receiving waters are related to
 chloramine concentrations.  Merkens (1958)615 stated that
 toxicities  of free  chlorine and  chloramines were best esti-
 mated from  total chlorine  residuals. In monitoring pro-
 grams,  evaluation of chlorine  content of water is usually
 stated in terms  of  total chlorine  residuals.  Because the
 chlorine concentrations of concern  are below  the level of
 detection  by the orthotolidine method,  a  more  sensitive
 analytical technique is recommended.
   The literature summarized by McKcc and Wolf (1963)514
 showed  a wide range of acute chlorine toxicity to various
 aquatic organisms,  but the conditions of  the tests varied so
 widely  that  estimation of generally applicable  acute or
 safe  levels cannot be derived from  the combined  data. It
 has also been demonstrated  that small amounts of chlorine
 can  greatly  increase  the toxicity  of various industrial
   Merkens (1958)615 found  that at pH  7.0,   0.008 mg/1
 residual chlorine  killed half the test  fish in seven days. The
 test results were obtained using the  ainperometric  titration
 and  the diethyl-jft-phenylene  diamine methods  of  chlorine
 analysis. Zillich (1972),519 working with chlorinated sewage
 effluent, determined that  threshold  toxicity  for  fathead
 minnows  (Pimephales promelai) was 0.04-0.05 mg/1 residual
 chlorine. In two series of 96-hour LC50 tests an average of
 0.05-0.19 mg/1 residual chlorine was noted. Basch  et al.
 (1971)511  found 96-hour LC50 for  rainbow trout (Salmo
gaudneri}  to  be 0.23 mg/1.  Arthur and Eaton (1971),610
 working with fathead minnows and Gammarus pseudohmnaeus,
 found  that  the  96-hour LG50  total   residual   chlorine
 (as chloramine)  for Gammarus was 0.22 mg/1, and that
 all minnows were  dead  after 72  hours  at   0.15  mg/1.
 After seven days  exposure to 0.09 mg/1,  the first fish died.
 The LC50 for minnows was therefore between these levels.
 In chronic tests extending for 15 weeks, survival of Gammarus
was reduced at 0.04 mg/1, and reproduction was reduced at
0.0034 mg/1. Growth and survival of fathead minnows after
21 weeks was not affected by continuous exposure to 0.043
mg/1 total  chloramines, but fecundity  of  females was re-
duced. The highest level showing no  significant effect was
0.016 mg/1. Merkens (1958)515 postulated by extrapolation
that a concentration of 0.004 mg/1 residual chlorine would
permit one  half the  test fish to survive  one year.  Sprague
and Drury  (1969)616 have shown an avoidance response of
rainbow trout to free chlorine at 0.001 mg/1.
  Aquatic organisms  will tolerate longer short-term ex-
posures to much higher levels of chlorine than  the concen-
trations which have adverse chronic effects.  Brungs (1972)512
in a review  has noted that 1-hour LCSO's of fish vary from
0.74 to 0.88 mg/1, and that longer  short-term exposures
have LCSO's lower but still substantially  higher than ac-
ceptable for long-term exposure. Available information,
however, does  not show what effect  repeated  exposure to
these, or lower levels, will have on aquatic life.
  Because Gammarus, an essential food  for  fish, is affected
at 0.0034 mg/1, and a safe level is judged to  be one that
will not  permit adverse effect on  any  element of the biota,
the following recommendation has been made.

  Aquatic  life should be protected where the con-
centration of residual  chlorine in  the receiving
system  does  not exceed  0.003 mg/1 at any time  or
place. Aquatic organisms will  tolerate short-term
exposure to  high  levels  of chlorine. Until more is
known  about the short-term effects, it  is  recom-
mended that total  residual chlorine  should not
exceed 0.05 mg/1 for a period up to 30-minutes  in
any 24-hour period.

  The cyanide radical is a constituent of many  compounds
or complex  ions that may be present in industrial wastes.
Cyanide-bearing wastes may derive from gas works, coke
ovens,  scrubbing of gases in steel plants, metal plating
operations, and chemical industries. The  toxicity of cyanides
varies widely with pH, temperature, and dissolved oxygen
concentration.  The pH is especially  important, since the
toxicity of some cyanide complexes changes manyfold over
the range commonly found in receiving  waters.
  "Free  cyanide"  (CN~ ion and HCN) occurs mostly  as
molecular hydrogen cyanide, the more  toxic  form, at pH lev-
els of natural waters as well as in unusually acid waters. Fifty
per cent  ionization of the acid occurs  at  pH near 9.3.  Free
cyanide concentrations from 0.05  to 0.01 mg/1 as CN have
proved fatal to many  sensitive fishes  (Jones  1964),527 and
levels much above 0.2 mg/1 are rapidly  fatal  for most
species of fish. A level as low as 0.01 mg/1 is known to have
a pronounced,  rapid, and lasting effect  on the swimming
ability of salmonid fishes.

 190/Section HI—Freshwater Aquatic Life and Wildlife
  The work of Doudoroff et al. (1966)624 has demonstrated
that the effective toxicant to fish in nearly all solutions of
complex metallocyanides tested was molecular HGN,  the
complex ions being relatively  harmless. The total cyanide
content of such solutions is not a reliable index of their
toxicity. The HCN derives from dissociation of the complex
ions,  which can be greatly influenced  by pH  changes.
Doudoroff (1956)523 demonstrated a more than thousand-
fold increase of the toxicity of the nickelocyanide complex
associated with a decrease of pH from 8.0 to 6.5. A change
in pH from 7.8 to 7.5 increased the toxicity more than
  Burdick  and Lipschuetz (1948)521 have shown that so-
lutions  containing the  ferro and ferricyanide complexes
become highly toxic to fish through photodecomposition
upon  exposure to sunlight.  Numerous investigations have
shown that toxicity of free  cyanide increased at reduced
oxygen  concentrations  (Downing 1954,625 Wuhrmann and
Woker  1955,528  Burdick et al. 1958,520 Cairns and Scheier
1963).622 The  toxic  action  is known to  be  accelerated
markedly by increased temperature (Wuhrmann and Woker
1955,528 Cairns and Scheier 1963),622  but the influence of
temperature during long  exposure has not >been  demon-
strated. The toxicity of the nitriles (organic cyanides) to fish
varied greatly. Henderson et  al. (I960)526 found marked
cumulative  toxicity of  acrylonitrile.  Lactonitrile  decom-
posed rapidly  in water yielding free cyanide, and its high
toxicity evidently was due to the HCN formed.
  The  toxicity of cyanide  to  diatoms varied  little with
change of temperature and was a little greater in soft water
than  in hard  water (Patrick unpublished data  1971).529  For
Nitzchia linearis, concentrations found to cause a 50 per cent
reduction in growth of the population in  soft water  (44
mg/1  Ca-Mg as CaCO3) were 0.92 mg/1 (CN) at 72 F, 0.30
mg/1  at 82 F, and 0.28 mg/1 at 86 F. For Navicula seminulum
var. Hustedtil,  the concentrations reducing  growth of  the
population by 50 per cent in hard water (170 mg/1 Ca-Mg
as CaCO3) were found to be 0.36 mg/1 at 72 F, 0.49 mg/1
at 82 F, and 0.42  mg/1 at 86 F.  Cyanide appeared to be
more  toxic to  animals than to algae.
  Recommended maximum concentrations of cyanide-bear-
ing wastes of unknown  composition and properties should
be  determined by static and flow-through  bioassays.  The
bioassays should be performed with dissolved oxygen, tem-
perature, and pH held at the local water quality conditions
under which cyanides  are most toxic. Because  the partial
dissociation of some complex metallocyanide ions may be
slow,  static bioassays  may  reveal  much  greater  toxicity
than  that demonstrable by the flow-through methods.  On
the other hand, standing test solutions of simple and some
complex cyanides exposed to the atmosphere gradually  lose
their  toxicity,  because the volatile HCN escapes.
  Chemical determination of the concentration of undis-
sociated, molecular HCN alone  may be the best way to
evaluate the danger of free cyanide to fish in waters receiving
cyanide bearing wastes. Such tests may reveal the occi
rence of harmful concentrations of HCN not predictal
through  bioassay  of  the  wastes. Because an  acceptal:
concentration  of HCN or fraction of a LC50 of cyanic
and  cyanide-bearing effluents has not yet been positive
determined, a conservative  estimate must be made; ai
because levels as low as 0.01 mg/1 have  proved harmi
under some conditions, a factor of 0.05 should be applii
to LC50 levels.

  Once a 96-hour LC50 has been determined usit
the receiving water in question and the most sens
tive important species in the locality as the te
organism, a concentration of  free cyanide  (CN
safe to aquatic life in that water can be estimate
by multiplying the 96-hour LC50 by an applicatic
factor  of  0.05; but no  concentration greater tha
0.005 mg/1 is recommended at any time or place

  Detergents are a common component of sewage and i
dustrial effluents derived in Largest amounts from househo
cleaning agents. In  1965 a shift from tetrapropylene-deriv<
alkylbenzene sulfonates (ABS)  to the more biodegradab
linear alkylate sulfonates (LAS) was made by the deterge
industry. In current detergent formulas. LAS is the primal
toxic active compound, two to four times more  toxic th;
ABS (Pickering 1966).534 However, toxicity of LAS di
appears along with the metbylene  blue  active  substanc
(MBAS) response  upon biodegradation (Swisher 1967).5
Retrieval  of MBAS data  from the National Surveillam
Stations  throughout the U.S.  from  1966 to the  presei
showed  that the mean of 3,608 samples was less than 0
mg/1. There has been a downward trend in MBAS concei
trations. Only four stations  reported  mean concentratioi
greater  than 0.2 mg/1.
  The MBAS determination has been the routine analytic,
method for measurement of surfactant concentrations. Pos
tive  errors are more  common than negative ones in tk
determination of anionic  surfactants in water  (Standar
Methods 1971).536 An  infrared determination or a carbc
absorption cleanup procedure is recommended when hit>
MBAS concentrations are found.
  Marchetti (1965)533 critically reviewed  the effects of d<
tergents  on aquatic life.  Most available  information o
LAS toxicity relates to fish. Short term studies by a numlx
of investigators have  shown  (hat lethal concentrations t
selected fish species vary from 0.2 to 10.0  mg/1 (Hokanso
and  Smith 1971).632 Bardach et al.  (1965)631 reported tliE
10 mg/1 is lethal to bullheads (Ictalurus sp.), arid  that 0.
mg/1 eroded 50 per cent of their taste buds within 24 day:
Thatcher and  Santner (1966)5;i8 found 96-hour LC50 value
from 3.3 to 6.4 mg/1 for five species of fish.
   Pickering and Thatcher (1 970)536 found in their study c

                                                                                           7 oxic Substances /191
 chronic toxicity that a concentration of 0.63 mg/1 had no
 measurable effect, on the life cycle of the fathead minnow
 (Pimephalespromelas), while a concentration of 1.2 mg/1 was
 lethal  to  the newly hatched  fry. A safe level should be
 between 14 and 28 per cent of the 96-hour LC50. Hokanson
 and Smith (1971)532 reported that a concentration of 1 mg/1
 was an approximate safe  concentration for bluegills  in
 Mississippi River water of good quality.  Arthur  (1970)630
 found  that the  no-effect level of LAS on  Gammanis pseudo-
 limnaeus was 0.2 to 0.4 mg/1. This investigator also subjected
 opculate and  pulmonate  snails  to  60-week exposures  of
 LAS and  showed the  toxicity levels to  be 0.4 to  1.0 mg/1
 and greater than 4.4 mg/1, respectively.

 Detergent Builders

  Phosphates have been included in household detergents
 to increase their effectiveness, although this use has been
 seriously questioned recently. Nitrilotriacctate (NTA) and
 other builders have been tried, but most  are either less
effective or have been barred for reasons of potential health
 hazard. Available builders do not have serious direct effects
 on fish or  aquatic organisms at  concentrations likely to be
encountered in  receiving waters. In view of the uncertain
legal  status  of  present commercial detergents  and the
extensive search for adequate substitutes  now in  progress,
recommendations for builders arc not practical at this time.
 However,  it can  be stated that a satisfactory builder should
 be  biologically  degradable  and  nontoxic  to   aquatic
 organisms and humans, and that it should  not cause aes-
 thetic problems in the receiving  water.


  Once a 96-hour LC50 has been determined using
 the receiving water in question and the most sensi-
tive important species in the locality as the test
organism, a concentration of LAS safe to aquatic
life in that water can be estimated by multiplying
 the 96-hour LC50 by an application factor of 0.05;
but no concentration greater than  0.2  mg/1 is
recommended at  any time or place.


  Phenols and phenolic wastes are derived from petroleum,
coke,  and chemical  industries; wood distillation; and do-
mestic and animal wastes. Many phenolic compounds are
more toxic than  pure phenol: their toxicity varies with the
combinations and general nature of total  wastes.  Acute
toxicity of pure  phenol varies  between 0.079 mg/1 in 30
minutes to minnows, and 56.0 mg/1 in 96 hours to mosquito
fish (Gambusia affims).  Mitrovic et  al.  (1968)641  found  a
48-hour LC50 of 7.5 mg/1 to trout; they noted that exposure
to 6.5  mg/1 caused  damage to epithelial  cells in  2 hours,
and extensive damage  to reproductive  systems in  7 days.
 Ellis (1937)539  reported  1.0 mg/1 safe to trout; and 0.10
mg/1 was found nonlethal to bluegill (Lepomis  macrochirus)
in 48 hours (Turnbull et al. 1954).542 These studies illustrated
the wide range of phenol toxicity. There is not yet adequate
documentation  about chronic effects and toxicity of mixed
wastes on which to base recommendations of safe levels for
  Phenolics affect the  taste of fish  at  levels  that do not
appear to  affect fish physiology adversely. Mixed wastes
often have more objectionable effects than pure materials.
For example, 2,4-dicholorphenol affects taste  at 0.001  to
0.005  mg/1:  />-chlorophenol  at  0.01 to  0.06  mg/1; and
2-methyl, 6-chlorophcnol at 0.003 mg/1. (See the discussion
of Tainting Substances, p. 147.) Pure phenol did not affect
taste until levels of 1 to  10 mg/1 were reached (Fetterolf
1964).S4° The  taste of  fish in  most polluted  situations is
adversely affected  by phenolics  before  acute  toxic effects
are observed.

  In view of  the wide range of  concentrations of
phenolics which produce toxic  effects in fish and
the generally lower levels which taint fish flesh,  it
is recommended that taste and odor criteria  be
used  to determine  suitability  of  waste receiving
waters to support usable fish populations.  Where
problems of fish kills occur or fish  are subjected to
occasional short-term exposure  to phenolic com-
pounds, a 96-hour  LC50  should  be determined
using the receiving water in question and the most
sensitive important  fish in the locality as the test
animal.  Concentrations of  phenolic compounds
safe to fish in that water can then  be estimated by
multiplying  the 96-hour  LC50  by an application
factor of  0.05; but no concentration greater than
0.1   mg/1  is recommended at any time  or place.
Tests of other species will be necessary  to protect
other trophic levels.

  Sulfides are constituents of many industrial wastes, such
as those from tanneries,  paper  mills, chemical plants, and
gas  works. Hydrogen sulfide  may be  generated  by the
anaerobic  decomposition  of  sewage and  other   organic
matter in the water, and in sludge beds. Natural production
of HoS may also result from deposits of organic material.
  When soluble sulfidcs  are added  to  water,  they  react
with hydrogen ions to form HS~ or H2S, the proportion of
each depending on the  pH values. The  toxicity of sulfides
derives primarily from H2S rather than the sulfide ion. The
rapid combination of HoS with other materials, including
oxygen, has frequently caused investigators to overlook the
importance of HoS as it  affects aquatic life, especially when
it originates from sludge beds. Because  water  samples
usually are not  taken at the mud/water interface, the im-
portance of H2S in this habitat for fish  eggs, fish fry, and

192/Section III—Freshwater Aquatic Life and Wildlife

                90 0

                80 0











                                                             7 2
                                                                                         8 0
                                                                                                       8 4
FIGURE III-ll—Percentage of Hydrogen Sulfide in the Form of Vndissociated H2S at Various pH Levels (Temperature
                                               20 C; ionic strength n = 0.01)

                                                                                              Toxic Substances/193
fish food organisms is often overlooked (Colby and  Smith
   Hydrogen sulfide is a poisonous gas, soluble in water to
the extent of about 4,000 mg/1 at 20 C and one atmosphere
of pressure  (Figure III-ll). Upon solution, it dissociates
according  to the reaction H2S—>HS~+H+  and  HS~—>
S—+H+. At pH 9, about 99 per cent of the sulfide is in
the form of HS~; at pH 7 it is about equally divided between
HS~ and  H2S; and at pH 5 about 99 per cent is present
as H2S.
   Consequently,  the toxicity of sulfides increases at lower
pH because a greater proportion is in the form of undissoci-
ated H2S.  Only  at pH  10 and above is the sulfide ion
present in  appreciable amounts.  In  polluted  situations,
where the pH may be  neutral or below 7.0, or where oxygen
levels are low but not lethal, problems arising from sulfides
or from hydrogen sulfide  generated in sludge deposits will
be increased.
   Much available data on the toxicity of hydrogen sulfide
to fish and aquatic life have been based on extremely short
exposure periods  and  have failed  to  give  adequate infor-
mation  on water  quality,  oxygen, and pH. Consequently,
early data have suggested that concentrations between 0.3
and  4.0 mg/1 permit fish to  survive  (Schaut  1939,r'46
VanHorn 1958,550 Bonn and Follis 1967,544 Theedc et al.
1969).54<) Recent  data both in  field situations and  under
controlled  laboratory  conditions demonstrated hydrogen
sulfide toxicity at lower concentrations.  Colby and  Smith
(1967)015 found that  concentrations as high as 0.7 mg/1
were found  within 20 mm of the  bottom  on sludge beds,
and that levels of  0.1 to 0.02 mg/1 were common within the
first 20  mm of water above this  layer. Walleye (Stizostedion
mtreum r.) eggs held in trays in this  zone did not hatch.
Adelman  and Smith  (1970)543  reported that hatching of
northern pike (Esox luaus) eggs was substantially reduced
at 0.025 mg/1  of H2S, and at  0.047 mg/1 mortality  was
almost  complete.  Northern pike fry had 96-hour  LC50
values that varied  from  0.017  to 0.032  mg/1 at normal
oxygen  levels (6.0 mg/1). The highest concentration of
hydrogen  sulfide  at which no short-term effects on eggs or
fry were observed was 0.814 mg/1.  Smith and Oseid  (in
press 1971),548 working on eggs, fry, and juveniles of walleyes
and white  suckers  (Catostomus commersonni),  and   Smith
(1971),547  working  on walleyes  and  fathead  minnows
(Pimephales  promelas),  found that  safe levels varied  from
0.0029 to 0.012 ing /I with eggs being the least sensitive and
TABLE 111-20—96-Hour LC50 and Safe Levels Based on No
       Adverse Effect on Critical Life History Stages
                               96-Hr. LC (mg/1)
                                            Safe levels" (mc/l)
Northern Pike


White Sucker

Fathead minnows


Gamnurus pseudolimnaeus
Heragema limbata

0 007

0.032 (at 20C)
0.042 (10-day)

 " Safe levels are construed to mean no demonstrable deleterious effect on survival or growth after long-term
chronic exposure.
juveniles being the most sensitive in short-term tests (Table
111-20). In 96-hour bioassays fathead minnows and goldfish
(Carasstus auralus) varied greatly in tolerance to hydrogen
sulfide with  changes  in  temperature.  They were more
tolerant at low temperatures (6 to  10 C).
  On  the  basis of chronic tests  evaluating  growth and
survival,  the  safe level  for bluegill  (Lepomis macrochirus)
juveniles and adults was 0.002 mg/1. White sucker eggs  all
hatched at 0.015 mg/1, but juveniles showed a  negligible
growth reduction  at  0.002 mg/1.  Safe levels for fathead
minnows were between 0.002  and 0.003 mg/1. Studies  on
various arthropods  (Gammarus pseudolimnaeus and Hexagenia
limbata),  useful as fish food, indicated that safe levels were
between 0.002 and 0.003 mg/1 (Smith 1971).647 Some species
typical of normally stressed habitats were much more  re-
sistant (Asellus sp.).

  On  the basis of available data, a level of undis-
sociated hydrogen sulfide assumed  to  be safe for
all  aquatic  organisms including  fish is  0.002 mg/1.
At a pH of 6.0 and a temperature of 13.0 C, approxi-
mately 99 per cent of the total sulfide is present  as
undissociated  hydrogen sulfide. Therefore, to pro-
tect aquatic organisms within the acceptable limits
of  pH and  temperature, it is recommended that
the concentration of total sulfides not exceed 0.002
mg/1 at any time or place.

  In this report, wildlife is defined as all species of verte-
brates other than fish and man.  To assure  the short-term
and long-term survival of wildlife, the water of the aquatic
ecosystem must  be  of the quality and quantity to  furnish
the necessary life support throughout the life-cycle of the
species involved. In addition to the quantity, the quality of
food substances produced by the aquatic environment must
be adequate to support  the long-term survival of the wild-
life species.
  Many species  of wildlife require the existence of specific,
complex, and relatively undisturbed ecosystems for their
continued  existence.  Aquatic  ecosystems,  such  as bogs,
muskegs,  seepages,  swamps,  and  marshes,  can  exhibit
marked fragility under the influence of changing  water
levels, various pollutants, fire,  or  human activity. Changes
in the abundance  of animal  populations living in  such
aquatic communities can result  in  reactions  and  altered
abundance of plant life, which in turn will have repercus-
sions of other species of animal life. In general, these transi-
tional ecosystems between land and water are characterized
by very high productivity and importance for wildlife,  and
they should thus be maintained in that state to the greatest
possible extent.
  In many instances, criteria  to  protect fish and inverte-
brates or to provide water suitable for consumption by man
or domestic animals will also provide the minimal requisites
for some species of wildlife. This  would be true  for species
that use water only for direct consumption or that feed on
aquatic organisms to only a minor extent. For many species
of wildlife, however, the setting of water quality  criteria is
complicated by their ecological position at the apex of com-
plex food  webs,  and also by the  extreme mobility of some
wildlife, especially birds.
  Those substances which are concentrated via food chains,
such as many chlorinated hydrocarbons, present  special
problems for those species that occupy the apex of long food
chains.  In those instances, environmental levels which are
safe for fish, do not necessarily convey safety to predators or
even to scavengers that consume fish.
  A number of factors can be identified that can affe
specific components of the ecosystem and cause reduo
food and shelter  for wildlife. These factors also affect fi
and other squatic life and therefore are discussed in great
detail in appropriate related subtopics.

  In bioassays with aquatic plants, Sincock (1968)893foui
that when the pH of the water in test vessels dropped to 4,
reedhead-grass (Potamogeton perfoliatus),  a valuable wate
fowl food plant, died within a few days.  Similarly, in Ba
Bay, Virginia,  between August and November,  1963, t
aquatic plant production declined  from 164 to 13 poun
per acre. This  atypical decline  was immediately preced>
by a decline in pH to 6.5 compared to previous midsumm
readings of 7.7 to 9.2.  (U.S. Bureau of Sport Fisheries ai

  Aquatic plants of greatest value as food for wate
fowl thrive best in waters with a summer pH rani
of 7.0 to 9.2.


  Generally, waters with reasonably high bicarbonate alk
Unity are more productive of valuable waterfowl food plar
than are waters with low bic arbonate alkalinity. Few wate
with less than 25 mg/1 bicarbonate alkalinity can be classi
among the better waterfowl habitats. Many waterfowl hat
tats productive of valuable foods,  such  as sago pondwei
(Potamogeton pectinatus), widgeongrass (Rappia maritima at
R. occidentalis), banana waterlily (Castalia flava), wild celer
(Vallisneria americana),  and others have a bicarbonate alk
Unity range of 35 to 200 mg/1.
   Definitive submerged aquatic plant communities devek
in  waters  with  different  concentrations of bicarbona

 alkalinity.  It is logical to assume that excessive and pro-
 longed fluctuation in alkalinity would not be conducive to
 stabilization of any one plant community type.  Sufficient
 experimental evidence is not available to define the effects
 of various  degrees and rates  of change in alkalinity on
 aquatic plant communities. Fluctuations of 50 mg/1 prob-
 ably  would contribute to  unstable  plant communities.
 Fluctuations of this magnitude may be due to canals con-
 necting watersheds, diversion of irrigation water, or flood
 diversion canals (Federal Water Pollution Control Adminis-
 tration 1968, hereafter referred to as FWPCA 1968).562

  Waterfowl habitats  should  have a bicarbonate
 alkalinity between  30 and 130 mg/1 to  be pro-
 ductive. Fluctuations should be less than 50 mg/1
 from natural conditions.


  Salinity  can  also affect plant communities.  All saline
 water communities, from slightly brackish to marine, pro-
 duce  valuable waterfowl  foods, and the most  important
 consideration is the degree of fluctuation of salinity. The
 germination of seeds and the growth of seedlings are critical
 stages in the plant-salinity relationship; plants become more
 tolerant to  salinity with age.
  Salinities from  0.35 to  0.9  per cent NaCl in drinking
water have been shown to be toxic to many members of the
order Galliformes (chickens, pheasant, quail) (Krista et al.
 1961,585 Scrivner  1946,592 Field  and  Evans 1946661).
  Young ducklings were killed or retarded in growth as  a
result of salt poisoning by solutions equal to those found on
the Suisun  Marsh, California, during the summer months.
Salinity maxima varied from 0.55 to 1.74 per cent, and the
means varied from 0.07  to 1.26 per cent during July from
 1956  to 1960 (Griffith 1962-63).565

  Salinity should be kept as close to natural con-
ditions as possible. Rapid  fluctuations should be


  Criteria  for  light penetration  established in  the discus-
sions  of Color (p.  130) and Settleable Solids (p. 129) should
also be adequate  to provide  for the production of aquatic
plants for freshwater wildlife.


  Accumulation of silt deposits are  destructive to aquatic
plants due  especially to  the creation of a soft,  semi-liquid
substratum inadequate for the  anchoring of roots. Back
Bay, Virginia, and Currituck Sound, North Carolina, serve
 as examples of the  destructive  nature  of  silt deposition.
 Approximately 40 square miles of bottom are covered with
 soft, semi-liquid silts up to 5 inches deep; these areas, con-
 stituting one-fifth of the total area, produce  only 1 per cent
 of the total aquatic plant production (FWPCA 1968).662

   Setteable substances  can destroy the usefulness
 of  aquatic bottoms to waterfowl, and  for that
 reason, settleable substances should be minimized
 in areas expected to support waterfowl.


  The production of protozoans, crustaceans,  aquatic  in-
 sects, other  invertebrates, and fish is  dependent on water
 quality. The water quality requirements for the production
 of fish are dealt with elsewhere in this Section, and a normal
 level of productivity of invertebrates is also required for the
 normal production of fish that feed upon them.
  While it is well known that many species of invertebrates
 are easily affected by low concentrations of pollutants, such
 as insecticides, in water (Gaufin etal. 1965,863 Burdicket al.
 1968,555 Kennedy et al. 1970584), most of the field studies do
 not supply  reliable  exposure  data, and most laboratory
 studies are of too short a duration or are performed under
 static conditions,  allowing  no reliable extrapolations to
 natural conditions. The general impression to  be gained
 from these studies is that insects and crustaceans tend to be
 as sensitive as or more sensitive than fish to  various insecti-
 cides, and that many molluscs and oligochetes tend to be
 less sensitive.


  The increasing discharge of warmed industrial  and do-
 mestic effluents into northern streams and lakes has changed
 the duration and extent of normal ice cover  in these north-
 ern regions. This  has prompted changes  in the  normal
 overwintering pattern of some species  of waterfowl. Thus,
 Hunt (1957)576 details the increasing use since 1930 of the
 Detroit  River  as a wintering area for  black duck (Anas
 rubripes), canvasback (Aythya valisneria), lesser scaup (Aythya
 qffines),  and redhead (Athya americana).  In this  process,
waterfowl may  become crowded  into areas  near industrial
complexes with  a  shrinking supply of winter food. The
 proximity of sources of pollutants, food shortages, and low
 air temperatures often interact to produce unusually high
waterfowl mortalities.

  Changes in natural freezing patterns and dates
 should  be  avoided as far  as possible in order to
 minimize  abnormal  concentrations of wintering

 196/Section HI—Freshwater Aquatic Life and Wildlife
Direct Acting Substances
  Oils  Waterbirds and aquatic mammals, such  as musk-
rat and otter, require water that is free from surface oil.
Catastrophic losses of waterbirds have resulted from the
contamination of plumages by oils. Diving  birds appear  to
be more susceptible to oiling than other species  (Hawkes
1961).671 Heavy contamination of the plumage results  in
loss of buoyancy and drowning. Lower levels of contamina-
tion cause excessive heat loss resulting in an energy deficit
which expresses itself in an accelerated starvation (Hartung
1967a).667 Less than 5 mg of oil per bird can produce sig-
nificant increases in heat loss. The ingestion  of  oils may
contribute to mortalities, and this is especially true for some
manufactured  oils  (Hartung  and Hunt  1966).569  When
small quantities of oil are coated  onto eggs by incubating
mallards (Anas platyrhynchos), the likelihood  of those eggs  to
hatch is greatly  reduced  (Hartung  1965).566  Rittinghaus
(1956)591 reported an incident in which numerous Cabot's
Terns (Tkalasseus sandvicensis) and other shorebirds became
contaminated with oil that had been washed on shore. Eggs
which were subsequently oiled by the plumage of oiled fe-
male terns did not hatch even after 50 days of incubation.
The absence of visible surface oils should  protect wildlife
from direct effect.
  Oils can  be sedimented  by coating particulates on the
surface  and then sinking to the bottom.  Sedimented oils
have been associated with changes in  benthic communities
(Hunt 1957)576 and have been shown to act as concentrators
for chlorinated  hydrocarbon  pesticides   (Hartung  and
Klingler 1970570).
  To protect waterfowl,  there should be no visible
floating oil (see p. 146 of this Section and pp. 263-264
of Section IV).
   Lead  Waterfowl often mistake spent lead shot for seed
or grit and ingest it. See Section  IV, pp.  227-228,  for  a
discussion of this problem.
  The recommendation of the Marine Aquatic Life
and Wildlife  Panel, Section IV,  (p. 228) to protect
waterfowl also applies to the freshwater environ-
   Botulism Poisoning   Botulism   is a  food  poisoning
caused by the ingestion of the toxin of Clostridium botulinum
of  any six  immunologically distinct  types, designated  A
through F. The disease, as it occurs in epizootic proportions
in wild birds, is most commonly of the C  type,  although
outbreaks of type E  botulism have been  observed on the
Great Lakes (Kaufman and Fay 1964582, Fay 1966660).
   Cl. botulinum,  a widely distributed  anaerobic bacterium,
is capable of existing for many years in its dormant spore
form, even under chemically and physically  adverse  e
vironmental conditions.  Its  toxins are  produced in  t
course of its metabolic activity as the vegetative form gro'
and  reproduces in suitable media. Outbreaks  occur wh
aquatic birds consume this preformed toxin.
  The highest morbidity and mortality rates from botulis
in aquatic birds have  been recorded in shallow,  alkali
lakes or marshes in the western United States, and outbrea
have most commonly occurred from July through  Septei
ber and, in some years,  October.  The optimum tempei
tures for growth of the bacterium or the toxin productic
or both, have  been reported as low as  25 C (Hunter et
1970)5" and as  high as 37 C (Quortrup and Sudheirr
1942588). The discrepancies are probably the result of diffi
ences in the experimental conditions under which the me;
urements were made and the strains of CL botulinum type
  The popular belief that avian botulism epizootics are ;
sociated with low water levels and consequent stagnation
not necessarily supported by facts. In three of the years
heaviest bird losses in the history of the Bear River Migi
tory Bird  Refuge (1965,  1967, and 1971), the water sup[
was  considerably  more  abundant than normal  (Hunt
California Department of P'ish and Game, personal  commu
cation; unpublished Bureau of Sport Fisheries and  Wildl
reports600). The  high water  levels  caused flooding of mi
flats not normally under water in the summer months. Sir
lar inundations of soil  that had been dry for several ye;
have been associated previously with outbreaks on  the Be
River Refuge  and in other epizootic areas. A partial  e
planation for these associations may be that flooding of d
ground is commonly followed by  a proliferation  of ma
species  of aquatic invertebrates  (McKnight 1970687),  t
carcasses of which may be utilized by Cl. botulinum.
  Bell et al. (1955)562 provided experimental support for
idea expressed earlier by Kalmbach (1934).681 According
their "rnicroenvirontnent concept," the bodies of inver
brate animals provide  the nutrients and the anaerobic t
vironment required by C. botulinum type C  for growth  a
toxin production. These bodies would presumably also of,
some protection to the bacterium and its toxin from a chen
cally unfavorable ambient  medium. Jensen and  All
(I960)578  presented evidence of a  possible relationship  t
tween die-offs  of certain invertebrate species and subseque
botulism outbreaks.
  The  relationship  between  alkalinity or salinity of  t
marsh and the occurrence of botulism outbreaks is not cle;
Invertebrate carcasses  suspended  in distilled water suppc
high levels of  toxin (Bell et  al. 1955).552 Laboratory mec
are  commonly composed of ingredients such  as peptoni
yeast extract, and glucose, without added salts. The mediu
used routinely at the Bear River Research Station for  t
culture of Cl.  botulinum type C has a pH of 6.8 to  7.0 aft
heat sterilization. McKee el al. (1958)686 showed that win
pH  was automatically maintained at a particular level

 laboratory cultures of Cl. botulinum type C throughout the
 growth period, the largest amount of toxin was produced at
 pH 5.7, the lowest level tested. Decomposing carcasses of
 birds dead of botulism commonly contain very high concen-
 trations of type C toxin, and in these cases production is
 ordinarily independent of the chemical composition of the
   Kalmbach (1934)581 tabulated the  salt  concentrations of
 water samples collected from 10 known botulism epizootic
 areas. The values ranged from 261 to 102,658 ppm  (omit-
 ting the highest, which was taken from a lake where the bird
 losses were possibly from a cause other than botulism).
   Christiansen and Low (1970)s:>6 recorded  conductance
 measurements on water in  the management units  of the
 Bear River Migratory Bird Refuge and the Farmington Bay
 Waterfowl Management Area, both  sites of botulism out-
 breaks varying in severity from year  to year.  The average
 conductance of water flowing into the five units of the Bear
 River Refuge in five summers (1959-1963) ranged from 3.7
 to 4.9 millimhos per centimeter at 25 C.  The readings on
 outflowing water from the five units ranged from 4.4 to 8.3
 mmhos.  Comparable figures for the three Farmington Bay
 units were 1.8 to 3.2  (inflow) and 3.2 to  4.8 mmhos (out-
 flow). Thus the salinity range of the inflowing water at Bear
 River  was comparable to that of the outflowing water at
   These data suggest that salt concentration of the water in
 an epizootic area is not one of the critical factors influencing
 the occurrence of outbreaks.  If high salinity does favor their
 occurrence,  it is probably not  because of its  effect on Cl.
 botulinum itself.  Other possible explanations for  the higher
 incidence of botulism in shallow, alkaline marshes are:
    •  Saline waters may support higher invertebrate popu-
       lation levels than do relatively fresh waters. (Com-
       parisons,  as they relate to avian botulism, have not
       been made.)
    •  High salinity may inhibit some of the microorganisms
       that compete with Cl. botulinum for nutrients or those
       that cause deterioration of the toxin.
    •  Salinity may have no significant effect on the  in-
       vertebrates or the bacteria, but it increases the sus-
       ceptibility of the birds. Cooch (1964)557 has shown
       that type  C botulinum toxin decreases the activity of
       the salt  gland in ducks, reducing its capacity to
       eliminate salt. Birds so affected succumb  to smaller
       doses  of toxin  than  do  those  provided with fresh
    •  Outbreaks of botulism poisoning tend to be associ-
       ated with or affected by insect die-offs, water tem-
       peratures above 70 F,  fluctuations in water levels and
       elevated concentrations of dissolved  solids.
   Outbreaks of botulism poisoning tend to be  as-
sociated with, or affected by  insect die-offs, water
 temperature  above  70 F, fluctuating water levels,
 and elevated  concentrations of  dissolved  solids.
 Management of these factors may reduce outbreaks
 of botulism poisoning.

 Substances  Acting  After Magnification in Food Chains

   Chlorinated Hydrocarbon Pesticides

   DDT and Derivatives   DDT  and  its abundant  de-
 rivatives DDE and TDE have high lipid solubility and low
 water solubility, and thus tend to concentrate in the lipid,
 i.e., living fraction  of  the aquatic environment (Hartung
 1967b).568 DDE is the most stable of the DDT compounds
 and has been especially implicated in producing thinning of
 egg shells, increased breakage of eggs, reproductive failure
 in species occupying the apex of aquatic food chains in areas
 with long histories of DDT usage.
   Reproductive failures  and local  extirpation associated
 with egg shell thinning have been reported for several North
 American bird species. The phenomenon was first described
 and is  most wide-spread for the peregrine falcon (Falco
 pertgrinus) (Hickey and  Anderson 1968).374 Since then simi-
 lar  phenomena have been  described  in  Brown  Pelicans
 (Pelecanus ocadetitalis) (Anderson  and Hickey  1970)551 and
 species  of several other  families of predatory birds. Further
 increases of DDE in large receiving basins, such as the Great
 Lakes,  would be expected to increase the extent of repro-
 ductive failure among predatory  aquatic bird populations.
 Concentrations  as low  as 2.8  ppm p ,//DDE on  a wet-
 weight  basis produced experimental thinning of egg shells in
 the  American   Kestrel  (Falco  spmvanus)  (\Viemeyer  and
 Porter  1970).5" Heath  et al. (1969)572  induced significant
 levels of eggshell thinning in mallards  after  feeding  them
 similarly low levels of DDE. Concentrations of DDT com-
 pounds in the water  of Lake Michigan have been estimated
 to be  1 to 3 parts  per trillion  (Reinert  1970)589 (Table
 111-21). Concentrations that would permit the assured sur-
 vival of sensitive predatory bird species are evidently much
 lower than that. Because such low concentrations cannot be
 reliably measured by present technologies and because the
 concentrating factor  for the food chains appears to be vari-
 able or is not known, or both, a biological monitoring sys-
 tem should be chosen. If it is desired to protect a number of
 fish-eating and raptorial birds,  it is essential to reduce the
 levels of DDE contamination, especially in large receiving
 basins  (see Section IV).
  The available data indicate that there should not be con-
centrations greater than  1  mg/kg of total DDT in any
aquatic plants or animals in order to protect most species of
aquatic wildlife. Present unpublished data indicate effects
for even lower levels of  DDE to some species of predatory
birds (Stickel unpublished data).m
  Present environmental levels vastly exceed the recom-
mended levels in many  locations, and continued direct or

 198/Section HI—Freshwater Aquatic Life and Wildlife
  TABLE 111-21—Relationship of DDT and Metabolites to
                  Eggshell Thinning

Prairie falcon (Falco

Japanese quail

Herring gull (Larus
American kestrel
(Falco sparvariiis)

Dosage* wet-
weight basis
. lOOOmg/kg
single dose


ca. 3.3ppm
total DDT
2.8 ppmp.p'DDE

"2.8 ppm DDE
"11. 2 ppm DDE
Pesticide level
in eggs

0-10 ppm DDE
1 0-20 ppm DDE
20-30 ppm DDE
30 ppm DDE
23.6 ppm o.pDDT
0.52 ppm DDE
48.0 ppm p.p'DDE
227 ppm total DDT

32 4 ppm DDE


ca. 5
ca. 13
ca. 18
ca. 25



Tucker & Haegele, 1970s'5

Enderson & Berger, 1970s5'

Bitmanetal., 1969«3

Keith, 1966*"

Wiemeyer & Porter, 1970s"

Heath et al., 1969S1!

 * All tests except the first one are chronic, spanning at least several months.
 " Converted from dry-basis.
 t Not determined.
indirect inputs of DDT would make these recommendations


  In order to protect most species of aquatic wild-
life, the total DDT concentration on a wet-weight
basis should be less than  1  mg/kg in any aquatic
plants or animals. (Also see Recommendations for
Pesticides, p. 185-186.)

  Polychlorinated Biphenyls (PCB)  Polychlorinated
biphenyls are chlorinated hydrocarbons which are  highly
resistant to chemical or biological degradation. They have
been widespread environmental contaminants (Jensen et al.
1969,580 Risebrough et al. 1968590). Their biological effects
at present  environmental concentrations are  not  known.
PCB's can elevate microsomal  enzyme activity (Risebrough
et al.  1968,590 Street et  al. 1968594), but the environmental
significance  of that finding is not clear.  The toxicity of
PCB is influenced by the presence of small amounts of con-
taminated chlorinated  dibenzofurans  (Vos  and Koeman
1970,596 Vos et al. 1970597)  which are highly toxic to d
veloping embryos.

  Because  of  the persistence of  PCB  and the
susceptibility  to  biological magnification, it :
recommended that  the body  burdens of  PCB i
birds and mammals not be permitted to increas
and that monitoring programs be instituted (se
Section IV).

  Westoo (1966)598 reported that almost all of the mercui
found  in  fish is methyl mercury. Jensen and  Jernelc
(1969)679 showed that natural sediments can methyla
ionic  mercury. Mercury  levels in  fish in Lake  St. Cla
ranged  between 0.4 and 3  ppm, averaging near 1.5 ppi
(Greig and Seagram 1970).£64 Residues in fish-eating bin
from Lake St.  Clair ranged up to 7.5 ppm in a tern, and u
to 23  ppm in a great blue heron (Dustman et al. 1970).5
These residues are comparable to those found  in  Swedis
birds  that  died after  experimental dosing with  methy
mercury, and  in birds that died with signs of mercury po
soning  under  field conditions  in  Scandinavian  countn
(Henriksson et al. 1966,5" Bor; etal. 1969,564 Holt 1969s".
To date, no bird mortalities due to mercury contaminatio
have  been  demonstrated  in the Lake St. Clair area, bt
body  burdens of fish-eating birds are obviously  close  t
demonstrated toxic levels. It is therefore concluded that th
mercury levels in fish flesh should be kept below 0.5 ppm I.
assure the long-term survival of fish-eating birds. Since thi
level incorporates little or no safety margin for fish-eatin
wildlife, it is suggested that the safety of a 0.5 ppm level b
reevaluated as soon as possible.

   Fish-eating birds should be protected if mercurj
levels in fish do not exceed 0.5 ^6/6-
   Since the  recommendation  of 0.5 /ug/g mercuri
in  fish provides little or no safety margin for fish'
eating wildlife, it is recommended that the safetj
of  the 0.5  Mg/g  level be reevaluated  as soon as

                                                      LITERATURE  CITED

1 Cairns, J., Jr. (1967), Suspended solids standards for the protection
     of aquatic organisms. Proc. Ind.  Waste Conf. Purdue Unw. 129(1):
2 Cairns, J.,  Jr., D. W.  Albaugh,  F. Busey,  and  M. D.  Chanay
     (1968), The sequential  comparison  index:  a simplified method
     for non-biologists to estimate relative  differences in biological
     diversity in stream pollution studies. J.  Water Pollut. Cantr. Fed.
3 Cairns, J., Jr. and K. L. Dickson (1971), A simple method for the
     biological  assessment of the effects of waste discharges on aquatic
     bottom-dwelling organisms. J.  Water  Pollut.  Contr. Fed. 43(5):
4 Galtsoff, P. S., W. A. Chipman, Jr., J. B.  Engle, and II. N. Calder-
     wood (1947), Ecological and physiological studies of the effect of
     sulfite pulpmill wastes on oysters in the York  River,  Virginia.
     Fish and Wildlife Service Fisheries Bulletin 43(51):59-186.
6 Hayclu,  E.  P. (1968), Biological concepts  in pollution control. In-
     diut. Water Eng. 5(7): 18-21.
6 Patrick, R., H. II. Holm, and J. H. Wallace (1954), A new method
     for determining  the  pattern  of the  diatom flora. Notulae Natur.
     (Philadelphia)  no. 259:1-12.
'Sparks, R. E., A.  G. Heath,  and J. Cairns, Jr. (1969), Changes in
     bluegill EKG and respiratory signal caused by exposure to con-
     centrations of zinc. Ass.  Southeast. Rial.  Butt. 16(2).-69.
8 Waller, W. T. and J. Cairns, Jr. (1969), Changes in movement pat-
     terns of fish exposed to  sublcthal  concentrations of zinc. Ass.
     Southeast. Bwl. Bull. 16(2):70.
9 Warren, C. E. and G. E. Davis (1971),  Laboratory  stream research:
     objectives, possibilities, and constraints. Annu. Rev. F.col. Systema-
     tic^ 2:111-144.


10 Alderdice, D. F.  (1967), The detection and measurement of water
     pollution:  biological  assays.  Can. Fish. Rep. no. 9:33-39.
11 American Public Health Association,  American  Water Works As-
     sociation,  and  Water  Pollution Control  Federation (1971),
     Standard methods for examination oj water and wastewater,  13th ed.
     (American Public Health Association, Washington, D. C.), 874p.
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                                     TABLE  OF CONTENTS
        Development of Recommendations	   217
  TECTED	   219
        Effects of Water Quality Change on Eco
          systems	   219
    FISHERIES	   221
        Application  of Water  Quality to  Aqua-
          culture 	   224
        Bases for Recommendations	   225
        Radionuclides	   226
          Recommendation	   226
        Heavy Metals	   226
          Recommendation	   226
        Polych orinated Biphenyls (PCB)	   226
          Recommendation	   226
        DDT Compounds	   226
          Recommendation	   227
        Aldrin, Dieldrin, Endrin, and Heptachlor. .   227
          Recommendation	   227
        Other  Chlorinated  Hydrocarbon  Pesti-
           cides	   227
          Recommendation	   227
        Lead	   227
          Recommendation	   228
        Mixing Zones	   231
    BIOANALYSIS	   233
    BIORESPONSE	   234
        Migrations	   236
        Behavior 	   236
        Incidence of Disease	   236
        Life Cycle	   236
        Physiological Processes	   237
        Genetic Effects	   237
        Nutrition and Food Chains	   237
        Effects on the Ecosystem	   237
        Food Value for Human Use	   237
      PH	   238
        Forms of Chemical  and  Environmental
          Interactions	   239
        Biological Effects	   239
        Metals	   240
        Alkalinity or Buffer Capacity, Carbon Di-
            oxide, and pH	   241
          Recommendation	   241
        Aluminum	   242
          Recommendation	   242
        Ammonia 	   242
          Recommendation	   242
        Antimony	   242
          Recommendation	   243
        Arsenic	   243
          Recommendation	   243
        Barium	   243
          Recommendation	   244
        Beryllium	   244
          Recommendation	   244
        Bismuth	   244
        Boron	   244
          Recommendation	   245
        Bromine   	   245
          Recommendation	   245
        Cadmium	   245
          Recommendation	   246
        Chlorine	   246
          Recommendation	   247
        Chromium	   247
          Recommendation	   247
        Copper	   247
          Recommendation	   248
        Cyanides	   248
          Recommendation	   248
        Fluorides	   248

    Sources of Oil Pollution	
    Biological  Effects of Petroleum  Hydrocar-
    Corrective Measures	

    Toxic ORGANICS	   264
        Bases for Recommendations	   269
          Recommendations	   269
    OXYGEN	   269
          Recommendation	   270
      VIRONMENT 	   270
        Characteristics  and  Sources  of  Radio-
          activity 	   271
        Exposure Pathways	   272
        Biological Effects of Ionizing Radiation. .   272
        Restrictions on Radioactive Materials. ...   273
        Conclusions	   273
          Recommendat'on	   274
        Magnitude of the Problem	   274
        Oxygen Depletion	   274
        Excessive Nutrient Enrichment	   275
        Pathogenic Microorganisms	   276
        Sludge Disposal into Marine Waters	   277
        Deep Sea Dumping	   277
        Potential Beneficial Uses of Sewage	   277
        Rationale for Establishing Recommenda-
            tions	   277
          Recommendations  	   277
      OCEAN DUMPING	   278
        Dredge Spoils 	   278
        Sewage Sludges	   279
        Solid Wastes	   280
        Industrial Wastes	   280
        Other Solid Wastes	   280
        Suspended Particulate Materials	   281
          Recommendations	   282

   The Panel on Marine Aquatic Life and Wildlife took as
its prime responsibility the development of recommenda-
tions that would reasonably assure protection of the marine
ecosystem. The recommendations have been discussed  at
various meetings of the members of the Panel and represent
a consensus on the best statement that can be made in the
light of present knowledge. The recommendations are not
inflexible and may be modified as our understanding of the
marine ecosystem improves.
   Many parts of  the marine ecosystem  do not meet the
quality requirements recommended here. As  a result  of
man's  activities,  the marine  ecosystem has been greatly
modified; many species are excluded from areas where they
were once abundant, and many areas have been closed for
the harvesting of marine products as human food because
of pollution.  The decision as to what part, and how much,
of the marine ecosystem should be protected for normal
aquatic life and wildlife has political, social, and economic
aspects, and such decisions cannot be based upon scientific
evidence alone. Although some marine pollution problems
are local in character, many are global and only the broad-
est possible approach can solve these problems.  Food from
the sea is already an important source of animal protein for
human nutrition,  and this continuing supply must not be
diminished b