EPA 910/9-77-036
JUNE 1977
SILVICULTURAL CHEMICALS
AND
PROTECTION OF
WATER QUALITY
U.S. ENVIRONMENTAL PROTECTION AGENCY
REGION X
1200 SIXTH AVENUE
SEATTLE, WASHINGTON 98101
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EPA 910/9-77-036
JUNE 1977
SILVICULTURAL CHEMICALS AND
PROTECTION OF WATER
QUALITY
Prepared Under Contract by:
Oregon State University
School of Forestry
Corvallis, Oregon 97331
The Project Director Was Michael Newton
Assisted by Joel A. Norgren
for
EPA Region X
This document is available to the public through the
National Technical Information Service, Springfield,
Virginia 22161.
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The Environmental Protection Agency,
Region X, has reviewed this report
and approved it for publication.
Mention of trade names or commercial
products does not constitute an en-
dorsement or recommendation for use.
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ACKVOWU3XJEMENTS
The authors of this- report received data, advice and physical assistance
from numerous individuals and agencies, without which, the document would have
"been substantially less complete. In particular, Logan Norris, U.S. Forest
Service, Pacific Northwest Forest and Range Experiment Station, George Brown
and Robert Beschta, Oregon State University, provided much assistance in re-
viewing the approach and early drafts of this study. Members of the National
Forest Products Association Forest Chemicals Action Committee, chaired by
William Lawrence, reviewed the approach and early drafts, Samuel Krammes,
U.S. Forest Service, Washington, D.C. provided consultation and large numbers
of references used as resource material. George Dissmeyer, Dan Bacon, and
Bill Stevenson, U.S. Forest Service, Atlanta, contributed time for consultation
and furnished considerable published and unpublished data.
Numerous persons from various offices of the Environmental Protection
Agency contributed in various ways. From the Washington office, Tom
Burkhalter and Bernard Smale provided consultation, office space and secre-
tarial assistance. Sam Fluker and James Crooks, in Atlanta, furnished data
and reports from the Southeast Region. Bill Clothier, Region X, assisted by
Duane Tucker and Elbert Moore, coordinated the project throughout and pro-
vided assistance, editorial guidance and general support throughout the pro-
ject.
Special acknowledgement is given to the many reviewers whose painstaking
efforts contributed substantially to accuracy and completeness of this docu-
ment.
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TABLE OF CONTENTS
Page
List of Figures vii
List of Tables viii
CHAPTER 1
WATER QUALITY GOALS AND SILVICULTURAL CHEMICALS 1
Purpose 1
Scope of Chemicals in Forestry 2
Approach 4
The Nature of This Report 5
CHAPTER 2
PRIORITIES IN POLLUTION CONTROL, BASED ON HAZARDS AND THEIR CAUSES 6
CHAPTER 3
GENERAL SCOPE OF CHEMICAL USAGE IN THE PRACTICE OF SILVICULTURE ... 11
Categories of Use and Objectives of Their Use 12
Fertilizers - Chemicals Used to Increase Productivity 12
Herbicides - Chemicals Used to Improve Plant Species 12
Composition
Insecticides and Rodenticides - Chemicals Used on 15
Animal Pests
Quantities of Chemicals Used in the Practice of Silviculture ... 16
Effects of Forest Chemicals on Water Quality 18
Relation Between Forests and Other Watersheds 26
Chemicals and Multiple Use Resource Values 27
Resiliency of Forest Ecosystems 30
Problems and Practices Entailing Aerial Applications of 36
Chemicals, and Alternatives
Nitrogen Deficiency 36
Phosphorus Deficiency 39
Moisture Deficiency Attributable to Herbaceous Weeds 39
Shade and Litter Problems—Brush and Hardwood Competition ... 43
Defoliation by Insects 47
Damage by Rodents to Desirable Tree Species 49
CHAPTER 4
CRITERIA FOR LIMITING CONCENTRATIONS OF CHEMICALS IN WATER 52
Relation Between Dosage and Response 54
The "No-Effect" Level of Toxic Chemicals 55
The Roles of Concentration and Exposure in Estimating Toxic • • • • 63
Hazard
Application Factors Used in Setting Water Quality Targets 67
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CONTENTS
Page
Proposed Criteria for Water Concentrations in Forest 70
Watersheds
Nitrate 72
Phosphate 73
Amitrole 73
Ammonium Ethyl Carbamoyl Phosphonate 75
Arsenicals 76
Dalapon 79
Di camba 80
Dinoseb 81
Pieloram 81
Silvex 83
S-Triazines 85
2,4-D 86
2,4,5-T 88
TCDD 91
Carbaryl 93
Diazinon 95
Disulfoton 96
Endosulfan 97
Endrin 98
Fenitrothion 99
Guthion 101
Lindane 102
Malathion 103
Phosphamidon 105
Trichlorfon 106
CHAPTER 5
BEHAVIOR OF CHEMICALS USED IN SILVICULTURAL OPERATIONS 107
Physical Properties of Silvicultural Chemicals in Relation 108
to Mobility in Soil
Fertilizer 108
Pesticides 110
Routes of Chemical Movement in Water 110
Influence of Application Method on Stream Contamination 114
Environmental Factors Affecting Appearance of 120
Silvicultural Chemicals in Water
Patterns of Appearance of Silvicultural Chemicals in Water 122
Relation Between Concentration of Chemical in Water and 126
Biological Activity
Fertilizers 127
Pesticides 131
Interaction Between Chemicals and Stream Environment 134
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CONTENTS
Page
Effects of Operational Measures to Reduce Pollution 139
Role of Buffer Strips in Reducing Pollution 139
Effect of Application Method 142
Sources of Trouble 144
Resource Costs in Pollution Control 146
CHAPTER 6
POLLUTION CONTROL GUIDELINES 157
Priorities for Pollution Control 158
Rules for Application of Chemicals in Silviculture 160
Monitoring 161
REFERENCES 168
APPENDICES
I. Toxicity Data for Silvicultural Chemicals to 178
Non-Target Organisms
II. References for Appendix Table 1 206
III. Checklist of Species for Which Toxicity Data is Given 212
IV. Glossary 215
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LIST OF FIGURES
Figure Page
1 Typical dose-response curve for an animal population 57
fed a toxic substance.
2 Normal distribution of sample responses to incremental 58
levels of exposure to toxic substances.
3 Typical dose-response relationships for an insecticide 60
and a herbicide to various groups of organisms.
4 Comparison between a typical chemical concentration 65
pattern in streamwater resulting from aerial ap-
plication and a static concentration, representing
equal total exposure during a 24 hour period.
5 Schematic diagram showing the distribution of a rep- 112
resentative silvicultural chemical.
6 Graph showing representative fluctuation of urea-N 115
and nitrate-N concentrations in streamwater
following fertilization of a coniferous
watershed.
7 Percentage of nominal dosage reaching the ground, and 120
mass median diameter of an herbicide deposit out-
side of, and downwind from, a 200 acre project.
8 Graph showing representative pattern of pesticide 123
concentration in streamwater after spraying 10$
of the watershed.
9 Postulated effect of fertilization on stream biomass 129
and productivity.
10 Comparison between chemical (dye) concentrations in 134
streamwater at the area of application and a
point downstream.
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LIST OF TABLES
Table Page
1 Major pesticides used for silviculture in the United ........ 19
States, 1972.
2 Features of forest watersheds that increase or .............. 26
decrease the expectation of stream pollution
in relation to agricultural or other non-
forest watersheds.
Recommended concentration maxima for silvicultural .......... 11
chemicals by stream class and user group.
Stream factors affecting the duration and intensity ......... 140
of toxic hazard resulting from a pesticide
contamination .
Summary of effects of current silvicultural practices ....... 152
on water quality, aerial applications of chemicals
and alternative practices.
Guidelines for applying chemicals by aircraft, and .......... 165
water monitoring in silvicultural practices.
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CHAPTERl
WATER QUALITY GOALS
AND SILVICULTURAL CHEMICALS
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WATER QUALITY GOALS AND SILVICULTURAL CHEMICALS
Purpose
SILVICULTURAL CHEMICALS AND PROTECTION OF WATER QUALITY completes a
three-part documentation on state-of-the-art technology to minimize or
prevent nonpoint source pollution resulting from activities included in the
Environmental Protection Agency's Silviculture Project. The Silviculture
Project was organized under the provisions of Sec. 208, 1972 Amendments to
the Federal Water Pollution Control Act (FWPCA). The preceding two docu-
ments are:
1. Logging Roads and Protection of Water Quality, U.S. Environ-
mental Protection Agency, Region X, Water Div. 1200 6th Ave.,
Seattle, WA 98101. EPA 910/9-75-007. March 1975.
2. Forest Harvest, Residue Treatment, Reforestation and Protec-
tion of Water Quality. EPA 910/9/76-020. April 1976.
Provisions of the FWPCA amendments require that measures be taken to
control all types of man-caused water pollution. The procedures for the
implementation of this requirement are outlined in Guidelines for Areawide
Waste Treatment Management Planning (U.S. E.P.A., 1975). The stated ob-
jective of the 208 Program, overall is to "restore and maintain the chemi-
cal, physical, and biological integrity of the Nation's waters." To ach-
ieve this objective, "it is the national goal that, wherever attainable,
an interim goal of water quality which provides for the protection and
propagation of fish, shellfish, and wildlife, and for associated recreation
in and on the water, be achieved by July 1, 1983."
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The format for this report was "based on the above Guidelines (U.S.
E.P.A., 1975), which identified two focal points as steps in the elimina-
tion of non-point water pollution. These are: l) Identification of
"Best Management Practices" for new and existing pollution problems, and
2) Development of a non-point source management program to prevent pollu-
tion and promote use of the "Best Management Practices" earlier identified.
This document provides a comprehensive review of management practices in-
volving silvicultural chemicals and evaluates these in relation to both
water quality and silvicultural objectives. It then develops an array of
procedures among the best practices that permit the reaching of management
goals with negligible impact on water quality.
Scope of Chemicals in Forestry
Chemicals are used in forests for the protection and maintenance of a
resource that takes many years to mature. This production cycle may last
through several generations of humans, and many administrations. Applica-
tions of chemicals are prescribed for benefits that often accrue to future
generations without immediate financial rewards for the landowner. Under
the circumstances, the indiscriminate use of chemicals in forestry is ex-
tremely rare. When there is a use of chemicals that results in temporary
adverse effects on water quality it is generally done with the understand-
ing that there is some risk. Approval of such practices is usually given
only when a) damage to the overall forest resource will be reduced by
treatment, and b) when no alternative is available for use that is known
to be adequate in effectiveness.
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Corresponding to the EPA's mandate to control water pollution, the
public forest land managing agencies also have mandates to manage the
public forest lands for the sustained yield of forest products, wildlife,
forage, water and recreational opportunity in perpetuity. Much industrial
and private land is managed toward the same goals. The Forest Service has
developed management guidelines (Pierovich et_ al_., 1975) in which Best
Management Practices are prescribed in a wide variety of management situa-
tions. Among these practices, chemicals figure prominently as tools that
may be used so as to be consistent with all resource values. The environ-
mental context in which these tools are used deserves some attention.
There are about five hundred million acres of forest, about one fourth
of the contiguous states, considered as the forest resource base of the
United States. These are exclusive of the areas set aside for other pur-
poses, or too low in productivity to produce lumber and fiber economically.
About one-fourth is in federal ownership, and somewhat less is in industrial
forestry holdings. Of this resource base less than two million acres, or
0.4 percent, is likely to receive any chemical treatment in a given year.
The commercial forest lands are located in watersheds that supply much
of the water used for municipal and irrigation sources. The water is
usually of high quality, but natural events cause very large variations in
quality from standpoints of both users and aquatic life. The naturally
occurring biota in streams have evolved in a history of trauma, and their
survival has depended on enormous resiliency and adaptability.
Maintenance of the forest resource has a significant positive effect on
water quality. Forest resource management implies a very long-term horizon,
and resource management activities affecting water quality have a very brief
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effect in relation to the effect of the resulting forest during the 20-100
years following treatment. The infrequency of treatment, and the small
proportion of land area treated in any given year are important factors to
be considered in respect to pollution potential. Many forests that receive
treatment to place them under management will not return to derelict status
under continuous management, and may never be retreated in the same manner.
It is likely, however, that the intensively managed forests of the future
will receive chemical treatments of some kind for protection and mainten-
ance, and that adverse effects of such applications can be minimized.
Approach
Meeting the mandates for both environmental protection and commodity
production is clearly possible. To this end, guidelines developed in
Chapter 6 have assumed that the ultimate goal of resource management is
maximum sustainable renewable resource use with minimum total environmental
impact.
In the development of these guidelines, the following approach is taken.
Chemical use patterns are identified, together with the nature and basis of
the problems for which they are prescribed. In order to be sure to include
all the major problems, only those practices with significant chance of con-
taminating water are considered. The toxicological properties of silvicul-
tural chemicals are examined in detail, and water quality criteria are pro-
posed that observe a substantial margin of safety in keeping with the nature
of forest watershed biota. Principles of water quality are examined to fur-
nish the basis of use prescriptions so as to avoid contamination levels that
exceed the proposed criteria. Finally, a guide has been developed from the
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above principles that gives the land manager an array of practices permitting
the production and protection of forest crops on virtually every acre with-
out causing infringement on water quality as judged by the above criteria.
Within these guidelines, the manager may elect among practices in support of
a variety of land uses almost to the water's edge.
The Nature of This Report
This document can be used either as a state-of-the-art description of
present practices or as a guide for development of management practices. It
can also be used as a technical review of the toxicological properties of
the important pesticides used in forest management. Chapters 2, 3, and 5,
describe the scope of chemical usage and the effects of these practices and
their alternatives on water quality and other resource values. Chapter 6
offers a summary of guidelines for use of chemicals in forests so as to main-
tain water quality without compromising other resource values. Chapter 4
offers a summary review of toxicological properties of major forestry chemi-
cals, supported in the Appendix by a review of specific data on a wide var-
iety of organisms. Water quality criteria are proposed in Chapter L, so as
to provide enforceable standards toward which operators can gear their field
operations. The guidelines offered in Chapter 6 are designed so that op-
erators anywhere in the United States will meet the water quality criteria
through the use of any of several described management options, at their
discretion and as befits the set of problems on the site. A glossary of
technical terminology is provided in the Appendix to assist in the inter-
pretation of certain technical details in this document and the supportive
literature.
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CHAPTER2
PRIORITIES IN POLLUTION CONTROL
BASED ON HAZARDS AND THEIR CAUSES
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PRIORITIES IN POLLUTION CONTROL,
BASED ON HAZARDS AND THEIR CAUSES
The over all goal of water pollution control is to prevent, abate or
minimize identifiable adverse effects on all biological and social systems
arising from changes in water quality resulting from human activities. Devel-
opment of control guidelines relating to application of silvicultural chemicals
requires an evaluation of the harm resulting from their use and determination
of its various causes. An understanding of the causes and effects of pollu-
tion can lead to a rational selection of alternatives that prevent or mini-
mize adverse impact, thus facilitating achievement of water quality goals.
Chemicals are used for many purposes in forests. These include herbi-
cides used for vegetation management in reforestation, stand improvement,
wildlife habitat and watershed management; insecticides used for protection
against insect outbreaks and chemical fertilization to enhance productivity.
Most of the chemicals applied on a large scale are applied by aircraft.
They may find their way into water either by direct application to water or
by migration to streams by surface or subsurface flow.
Hazard occurs when chemicals enter ecosystems in such a way that non-
target organisms are exposed to harmful quantities. Reasonable pollution
control strategy depends on identifying the routes of entry and applying
materials in ways that minimize their ultimate deposition in waterways.
The scale of human activities in our half-billion acres of commercial
forests is large. The legacy of 300 million underproductive acres provides
evidence that certain widespread exploitive activities require additional
management inputs to avoid loss of productivity. Timber harvest dominates
these activities, and compensatory reforestation and other cultural practices
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are increasing rapidly. The latter are the foci of chemical usage, and the
need for such use is often a direct result of earlier harvesting and the
growing social importance of timber. The expectation of greater reliance on
timber as a renewable resource suggests that increased emphasis on chemicals
in the practice of silviculture is inevitable.
Application of chemicals by spraying precludes the absolute freedom from
chemical pollution. It is therefore likely that a small quantity of pollu-
tion can be anticipated in every major forest region. Intensity of chemi-
cal use within regions will vary according to the level of timber production.
Chapter 3 outlines in detail the scope of chemical usage in the practice of
silviculture, and water quality effects resulting therefrom. Chapters 4 and
5 later consider the consequences of use in detail.
Guidelines are needed for controlling pollutants resulting from use of
chemicals for several important reasons: The first is that it is virtually
impossible to remove pollutants by other than natural degradation means once
they are introduced. The second is that if chemicals are not present in
(adversely) significant quantities, no constraints are imposed by pollution
that limit the uses to which water can be put. Third, the possibilities of
unanticipated side effects from pollution are minimized by preventing pollu-
tants from entering the aquatic systems. Finally, a standard reference for
pollution control can be expected to upgrade the general quality of applica-
tion. It is important, however, that efforts to minimize chemical pollu-
tants do not have the undesirable result of stimulating activities that in-
crease non-chemical pollution. The guidelines suggested in Chapter 6 pro-
vide a choice of procedures for managers so that the least disruptive can be
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selected for any given management system. Thus, relative hazard supercedes
absolute toxicity in the ordering of control priorities.
There is a very large body of scientific literature describing behavior
of chemicals in forests, toxicity, and effects of economic use on resource
management. These data are valuable for developing insight into consequences
of regulating practices in various ways, from standpoints both of economics
and toxic hazard. But there are no precedents for the implementation of pol-
lution control guidelines in forest management, hence little opportunity to
evaluate results. Pollution control guidelines that require substantial
changes in operating procedure could be very costly. These costs must be
measured both in immediate economic terms and in the long-term social cost,
if any, of a change in resource management. These costs must be balanced
against known and postulated costs to human and biological resources impacted
by such pollution.
Comparisons of tangible costs of hazard and of hazard reduction is one
method of ranking priorities in pollution control. Value judgements must
also be made regarding intangible assets and unknown effects. These judge-
ments must be interpreted on the basis of current toxicologieal and monitor-
ing data, of which the latter may dwell within the range of concentrations
that produce no observable harmful responses. Clearly, the tangible cost
method does not apply exclusively in this instance, yet substantial justifi-
cation must be given for any proposal to regulate silvicultural activities
where there is a chance of adverse economic impact.
At some point, the question ultimately arises whether to tolerate cer-
tain levels of known harm to one group of organisms in order to promote or
restore the development of others. There are also the unknown potential
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injuries or gains about which some speculation may have to enter the decision
process. In nature, populations of virtually all organisms fluctuate under
the influence of others without influence on over-all resource values. Land
use patterns in forests have a prolonged effect on stream environment, re-
sulting from establishment, maintenance and harvest of the dominant forest
species. The short term effects of the practices used to achieve any given
specific objective are often lost in the many years of influence of the re-
sulting forest. Because fluctuations in watershed ecosystems already result
from both natural and management-oriented causes, consideration of water
quality for a particular few days during the life of a forest deserves spe-
cial attention. This topic is discussed in detail in Chapters 3 and 4.
The best management strategy is regarded here as the set of tactics
which produces the least total adverse effects on water quality. Water
quality must be measured in terms of the welfare of aquatic ecosystems and
potential water users. Reduction in chemical usage leads to impacts asso-
ciated with non-chemical alternatives. Therefore pollution control strate-
gies cannot be limited only to those practices dealing specifically with
chemicals because non-chemical alternatives may be more harmful. Considera-
tion of water quality criteria must therefore include the over-all balance
of chemical and physical pollutants and fluctuations therein.
Management priorities for pollution control strategy in this document
have as their targets the following factors, in order of importance:
l) Toxic hazard, with significance measured by degree
and duration of harmful effects and their attenuation by re-
commended procedures or their alternatives (Chapters 3, 4, 5
and 6).
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2) Resource tradeoff between aquatic and terrestrial resources,
where there is conflict (Chapter 3).
3) Cost of implementation (alternatives listed Chapter 6).
These will be used with the rationale that severe or prolonged toxic ha-
zard or sediment impact are unacceptable. Among the procedures which have
low impact, the guidelines will favor those that produce the least possi-
ble physical disturbance to the dominant forest or soils, within accepta-
ble economic limitations, while accomplishing the silvicultural objective
of maximizing timber or other commodity production. Among the choices
that meet water quality and silvicultural objectives, there may be several
procedures possible from which operators can be free to choose according to
specific objectives, cost and available equipment. These procedures are
listed in the guidelines for water pollution control, Chapter 6.
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CHAPTERS
GENERAL SCOPE OF CHEMICAL USAGE
IN THE PRACTICE OF SILVICULTURE
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GENERAL SCOPE OF CHEMICAL USAGE
INTHEPRACTICEOFSn,\lClJLTURE
Silvicultural chemicals may be categorized in three general groups ac-
cording to the broad objective of use. In the first group, which includes
only fertilizers, the general intent is to increase the over-all productivity
of forest ecosystems. The specific intent is to thereby increase producti-
vity of commercial tree species. Similar materials are used as fire retard-
ants; because of their low potential hazard and infrequent use near streams,
these materials will not be discussed separately. The second group includes
herbicides, and has as its general forestry objective the focusing of forest
productivity on selected species. This group ordinarily does not influence
innate productivity of ecosystems, but rather channels such productivity into
species of some special social value. The last group is devoted to the re-
duction of losses among commercially important tree species that are already
established. These chemicals are the insecticides and rodenticides, whose
specific targets are insect and animal pests to protect commercially desir-
able tree species from being damaged or destroyed. Many other chemicals are
used by the forest industries for nurseries, road surfacing and various other
purposes beyond the scope of silvicultural operations. This report is
limited in scope to those chemicals used in silviculture.
Chemicals are used as a very small but important part of a complex
technology that makes up the framework of forest management. Because the use
of chemicals in forests is unlike the uses of similar materials in agricul-
tural or industrial applications, it is germane to describe their use in
terms of the general system of operation peculiar to silviculture.
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Categories of Use and Objectives of Their Use
FERTILIZERS-CHEMICALS USED TO INCREASE PRODUCTIVITY
Fertilizers are receiving limited general use in forests today. There
are certain major exceptions, however, which make this group of chemicals
the one with the largest total poundage of silvicultural chemicals in use.
These exceptions are confined to several major forest industrial corpora-
tions and public agencies; the industrial applications comprise most of the
tonnage.
The primary objectives of fertilization are to overcome specific defi-
ciencies in essential nutrients for tree growth. These operations are fo-
cused in the Pacific Northwest, where nitrogen deficiencies are often en-
countered, and in the Southeast, where the lack of phosphorus often limits
tree growth directly and perhaps indirectly by limiting nitrogen fixation.
Fertilizers are usually applied to large areas by aircraft. Fertili-
zers, like most other silvicultural chemicals, are applied to a very small
proportion of the total commercial forest acreage each year, and applica-
tions to a given site occur infrequently. Levels of management on most for-
est lands have not yet reached the stage at which fertility is severely lim-
iting to economic yield. Thus, silvicultural use of chemical fertilizers is
in a very different category from the intensive and general use of the same
chemicals on agricultural lands.
HERBICIDES-CHEMICALS USED TO IMPROVE PLANT SPECIES COMPOSITION
This group of chemicals includes a diverse set of herbicidal materials,
and a wide range of silvicultural objectives involving control of a wide
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variety of undesirable herbs, shrubs, woody vines, and trees; the forest
"weeds." The nature and extent of problems in forests of the United States
will undoubtedly lead to wider usage of herbicides than of any other group
of chemicals.
Use of herbicides to enhance forest productivity rests on the general
principle that the productivity of a forest ecosystem is normally fixed.
Economic and social potentials of the ecosystem are based on the abundance,
growth rate and desirability of the dominant species. Where adequate stock-
ing of desirable species is maintained by judicious management, there is lit-
tle need for herbicides. Target species for herbicides are restricted to
those plants that use resources otherwise available to desirable species,
without providing tangible benefits. The same principle is used in weed con-
trol that is observed in harvest-caused deterioration of species composition:
i.e. the removal of dominant species promotes development of those that are
subdominant. The forests of the United States have been subjected to re-
moval of desirable species for up to 300 years. Unnaturally large components
of undesirable species are widespread. Where weed trees and shrubs are now
dominant, the composition of such deteriorated stands will remain relatively
poor until selective removal of weeds again favors desirable species. It is
to this end that herbicides are used. The variety of herbicide uses ranges
across the diversity of composition classes in the commercial forests of the
entire nation.
It is important in describing herbicide usage to identify a unique as-
pect of their use in the forest: herbicides affect only primary producers
(green plants) when applied at registered use rates. Despite a lack of di-
rect effects on other organisms, they influence all organisms that depend on
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any or all of the affected primary producers for food, cover or energy
sources. For this reason, herbicides are the most powerful management tools
at the forester's disposal. They may be used for controlling not only spe-
cies composition and stand structure, but also have the potential for reduc-
ing damage from wildlife, diseases, and insects. Because of their wide spec-
trum of effects, use of herbicides may be anticipated anywhere, and for al-
most any purpose.
Most of the herbicides used in forests are applied by aircraft. Rates
of application are within the ranges used in agriculture, and application is
usually limited to one or two treatments early in the life of a stand. Most
of the herbicides used in forestry are registered also for agricultural uses,
and have established residue tolerances in foodstuffs.
Few forest stands require general treatment after desirable species be-
come dominant. Stands placed under management may not require treatment in
the present sense after future harvests, because the weed problems of the
past will not normally recur. Herbicides are now usually used to correct
historical problems of fire, non-reforestation or cull hardwoods, and their
use is presently generally limited to one short period in the life of a for-
est when a forest is placed under management. As intensity of management in-
creases, future uses will undoubtedly occur in other patterns, however.
Application of herbicides in or near streams raises questions related
to water quality. Timber growing sites adjacent to streams often are among
the most productive, and the application of herbicides near creeks, partic-
ularly by aircraft, invariably results in some quantity being deposited in
the water. Buffer strips along watercourses are often left unsprayed in or-
der to reduce deposits in streams. This is the principal pollution control
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technique for aerially applied herbicides. Drift control nozzles and
spray adjuvants have also been used to reduce herbicide deposits outside the
target zones.
In contrast to the case with fertilizers, there is widespread use of
herbicides with ground application methods, including mist blowers, conven-
tional power sprayers and tree injectors. The latter method will account for
an increase in usage of herbicide in the decades to come as hardwood forests
of eastern United States are placed under managements but quantities applied
by these methods are presently small. In terms of future impact on water,
injected herbicides are of academic interest in relation to water quality.
This topic has received considerable attention in relation to the organic
arsenicals, but measurable contamination has not been found (Norris, 1974).
Further discussion of movement of herbicides not applied to open water will
be developed in Chapter 5.
INSECTICIDES AND RODENTICIDES-CHEMICALS USED ON ANIMAL PESTS
These chemicals are of particular concern in relation to aquatic systems
on account of their status as animal toxins. The insecticides, in particu-
lar, are targeted mainly on widespread epidemics of defoliating insects af-
fecting large continuous areas of commercially valuable timber. Regional
projects often include entire river drainage basins in general aerial appli-
cations .
Values of insect-vulnerable timber are often high; where treatment is
warranted, there is economic incentive for treating all infested stands. Un-
sprayed areas risk direct economic loss; they also can lead to residual
breeding populations of insects capable of reinfesting sprayed stands.
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The materials registered as insecticides for aerial application, with
the exception of endosulfan, are short-lived organophosphorus and carbamate
insecticides. Endosulfan is used principally on local insect outbreaks in
Christmas trees and ornamentals.
Non-residual biological agents are also used for controlling insects.
These suspensions of insect disease cultures are quite specific for insects.
Their effectiveness on insects and lack of known impact on non-target species
are encouraging. Nuclear polyhedrosis virus cultures have been used effect-
ively in several projects with considerable success and demonstrably low im-
pact on non-target terrestrial and aquatic species. This approach is now
registered for use on the Douglas-fir tussock moth. Even the most selective
of the chemical insecticides, however, are harmful to certain aquatic insects
and food chain species at concentrations below 0.1 mg/1 (see Appendix for
specific data).
Ground applied insecticides and rodenticides are used in such small
quantities in forests that their total effects on water quality are not
likely to be detectable. Areas tend to be small and isolated by untreated
strips from open water. Application rates of insecticides are typically low
in relation to agricultural uses.
Quantities of Chemicals Used in the Practice of Sflviculture
The quantity of a chemical used is important in two major respects.
The rate per acre influences the intensity of direct immediate contamination.
The total amount of chemical used in a zone or region and its distribution
in time and place determine the potential for long-term and large-scale con-
tamination of large water-courses. The former generally affects the
16
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likelihood of acute toxic hazard; the latter determines the potential for
chronic damage to aquatic systems and to large scale users of irrigation
water.
Chemicals applied to forests from aircraft are often used at dosage
rates similar to those used in agricultural operations. Movement into water
supplies is much less, per pound applied, however, because of low soil move-
ment. Their infrequency of use, and the intact status of most forest soils
and vegetation at the time of application minimizes movement. Fertilizers
and herbicides, in particular, are usually also applied in a patchwork fash-
ion some distance from users of potable or irrigation water. A given rate
of application therefore tends to have much less impact on water quality than
would a comparable dosage applied to farmland. A proportion of forested
streams in treated areas normally contains detectable amounts of chemical
immediately after application. Over all, however, forest uses of herbicides
and fertilizers have low impact per unit of use because the observed concen-
trations are considerably below those known to affect aquatic organisms ad-
versely (Frederiksen et_ al_., 1973), and applications are diffused in time and
place.
Insecticides are usually applied in very large regional projects in
which every watershed may be treated. Even though the same considerations
hold as for herbicides in regard to intact forest floors and vegetation,
there is more likelihood that large insecticide operations leading to a low
level of contamination in small streams will affect major river systems.
Total amounts of chemicals used in forests are difficult to estimate.
Sales are not segregated according to use, but major industrial and public
user groups maintain records for a large part of the intensively managed
17
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forest areas. Programs, especially of insecticides, vary considerably from
year to year. Table 1 lists a summary of Forest Service and industrial uses
of pesticides for one year to illustrate scope of forest usage.
Effects of Forest Chemicals on Water Quality
Chemicals presently used in forests enjoy a remarkable safety record in
many respects, including maintenance of stream productivity. This generali-
zation and the exceptions to it are fundamental to the development of a set
of pollution control guidelines. The basis for the generalization will be
considered first, followed by a technical review of pertinent data.
A large body of data has been gathered relating to concentrations of
herbicides and fertilizers in water. Relatively few data are available re-
garding concentrations of organophosphates and carbamates in water; much of
the insecticide research was focussed on the now-defunct DDT. In short, no
recognized reports of injury to stream life have come to the attention of
the writers relative to properly applied herbicides or fertilizers in for-
estry. Reports of general injury to fish have been confined to applications
of insecticides, principally chlorinated hydrocarbons, in large projects.
Most were prior to isolation of major streams from application patterns.
Fish kills have been restricted generally to localized stretches of water
and have been followed by recovery over periods of a few months to 3 years.
At least one incident, however, was reported in which substantial fish kill
was associated with an organophosphate (Hatfield, 1969). Unfortunately, the
expertise needed to evaluate impacts on inconspicuous food chain species has
been lacking for most projects. Evidence for low impact has often been re-
stricted to a small number of operations. Observations that have been made
are consistent, however, and are not in major conflict with laboratory data.
18
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Table 1. Reported pesticides used for silviculture in the United States,
1972. Compiled from U.S. Forest Service Pesticide Use Reports
and a National Forest Products Assoc. Survey representing ap-
proximately 32 million acres. Actual amounts are considerably
greater. Herbicide use does not fluctuate greatly, but insect-
icide listing for the one year is not representative.
Herbicides
2,4-D
2,4,5-T
Paraquat
Pi dor am
2,4-D & 2,4,5-T
2,4-D & Picloram
Amitrol
Dinoseb
MSMA
2,4-D & 2,4-DP
Stoddards Solvent
Atrazine
Cacodylic Acid
Simazine
2,4-D & Dicamba
2,4,5-TP (silvex)
Dichlorprop
Dicamba
Dalapon
2,4-D & Amitrole
2,4-D & Silvex
Diphenamid
2,4,5-T & Dicamba
2,4-D & Atrazine
Amitrole & Simazine
Amitrole, Bromacil & 2,4-D
Amitrole , Atrazine &
Simazine
Amitrole & Bromacil
Acres Treated
278,905*
189,517*
31,076
18,735*
14,907*
13,343*
6,979*
5,082
3,671*
3,405*
3,196*
2,664*
1,920*
1,773*
1,305*
1,073*
882*
857*
800*
580*
400*
329*
276*
252*
242*
Insecticides
Zectran
Carbaryl
Mirex
Malathion
Lindane
Chlordane
Benzene
hexa chloride
Thimet
Guthion
Phorate
Gar dona
Dime tho ate
Di-Syston
Rodenticides
Endrin
Chlorophacinone
Strychnine
Zinc Phosphide
Fungicides
Ziram
Thiram
Methyl bromide
Acres Treated
650, 4501
111,691*
6,320*
5,186*
4,154*
693
569
355
347*
150
115
90
73
Acres Treated
44,081*
10,110*
632
97
Acres Treated
9,107*
8,427*
4 , 320*
57
2Q# * Registered for use in forest.
or ornamentals, 1976.
26
Zectran is no longer being man-
ufactured.
19
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Concern with the possibility for harm to aquatic ecosystems from herbi-
cides and fertilizers prompted inquiry of water quality specialists from
several state and federal agencies in the Pacific Northwest, southwest and
Washington, D.C. In the absence of a pattern of harmful effects in the lit-
erature, these specialists were polled to determine if there were "worst
cases" on which to draw some inferences of value in silviculture.
The Nonpoint Sources Section of the Environmental Protection Agency,
Washington, D.C., reported no knowledge of any instances of aquatic ecosys-
tem damage directly attributable to presently registered uses of herbicides
and fertilizers in the practice of silviculture (Drs. Bernard Smale, Thomas
Burkhalter, personal communication). Similarly, the U.S. Forest Service
Division of Environment Research, Washington, D.C., reported no instances of
damage, although there are many records of detectable concentrations of chem-
icals (Dr. Samuel Krammes, personal communication). The U.S. Forest Service,
Southeastern Region, has made observations relating to water quality after
fertilization and herbicide applications. Forest fertilization with phos-
phate in the South has not measurably influenced water quality (Dr. George
Dissmeyer and Mr. Dan Bacon, personal communication). Objections to herbi-
cide applications have been filed in various national forests in the South
and Pacific Northwest, but there is no record of injury to persons, wildlife
or aquatic systems when these chemicals have been used in accordance with
registered use rates (U.S.D.A., 1975a, 1975b, 1975c). These observations
alone are inadequate evidence for a conclusion that harmful effects do not
occur. They are consistent, however, with the recorded contamination levels
and toxicity data discussed in detail in Chapters 4 and 5, and in the Appen-
dix. One recorded incident in Oregon involved the accidental placement at
20
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an unknown point of a large quantity of 2,4,5-T upstream from a salmon hatch-
ery. In an unpublished report to the Oregon Fish Commission, Newton and
Norris (Oregon State University, 1965) reported sustained levels in hatchery
ponds of more than 0.1 mg/1 for more than one day. Although there was no
obvious mortality pattern , possible effects of the herbicide may have been
obscured by heavy silt loads from an earlier storm.
The Southeastern Region of the Environmental Protection Agency similarly
had not observed aquatic system damage from silvicultural use of chemicals.
Dr. Sam Fluker, Chief of the Pesticides Branch, Southeastern Region, indi-
cated in an interview that the water quality problems related to pesticides
in the South were tied to direct application to open water or to bare soil.
Soil movement with heavy rains was described as leading to deposit of the
chemicals in water as they move with silt. Silt-associated pesticide move-
ment was not thought to be a problem in silviculture. Dissmeyer, (1973)
however, reported that major deposits of silt had an adverse impact on water
quality when non-chemical methods were used in the South for site preparation.
If used in combination with application of persistent pesticides, such meth-
ods would deposit pesticides as well as silt in the water.
In the Pacific Northwest, no damage reports were found relating aquatic
ecosystem damage to toxic action of herbicides. There apparently have been
instances in which oil carrier used for herbicides may have produced slicks
which caused localized fish kills in standing water (Dr. James Harper,
Oregon Department of Fish and Wildlife, Portland, Oregon, personal communica-
tion ).
Fertilizers have been studied in relation to the contamination of streams
with urea, nitrate, ammonia and nitrite. The review by Moore (l975b) of
21
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stream contamination resulting from fertilization observed that a very small
proportion of urea applied to a forest watershed finds its way to the
streams. At the time of application, some chemical falls directly into the
stream, and a pulse of elevated concentration moves downstream. Levels of
nitrogen fertilizers or their metabolites in streamwater do not apparently
approach maximum safe levels for streamwater as recommended for potable water
(U.S.D.I., 1968).
Indices of quality in relation to nitrate depend on the uses to which
the water will be put, and the type of drainageway the water must follow.
Potable water containing high nitrate concentrations is regarded as hazard-
ous to babies, and is limited to 10 mg/1 of nitrogen as nitrate for this
reason. Streams containing high nitrate levels are also implicated in eutro-
phication of ponds and lakes; a similar problem exists where phosphate con-
centrations are sufficiently great to stimulate development of the nitrogen-
fixing blue-green algae. The levels of fertility necessary to cause eutro-
phication are not fixed, however, and are dependent on the rate of turnover
in lakes, temperature and other factors. Variations in native nutrient
levels appear to equal or exceed the range associated with fertilizer use in
forests (Brown et_ al_., 1973; Moore, 1975). Thus, nutrient levels found in
forest watersheds are probably of minor significance in eutrophication of
rivers having few impoundments or lakes. This topic will be discussed in
detail in Chapter 5.
Herbicides have received considerable attention in relation to effects
of aerial sprays on water quality. Norris and coworkers (Morris and Moore,
1970; Norris et_ al_., 1965, 1966a, 1966b) have systematically monitored for-
est watersheds treated with phenoxy herbicides, amitrole, picloram and
22
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atrazine. This work has been undertaken under conditions of operational use
where buffer strips have been both present and absent. In terms of toxic
hazard to wildlife, herbicide concentrations seldom occur at a peak level
equal to those known to cause harm to fish or other wildlife. Furthermore,
the observed peaks of concentration have generally persisted for a matter of
minutes or hours, dropping to the detection limits within two days after ap-
plication. An important exception to this pattern was observed in a range-
land treatment of a marshy area with shallow, slow-moving water (Norris,
1967).
Herbicides are specific in their activity on plants. Concentrations of
herbicides in water are generally lower than those known to cause injury to
crops through irrigation water (Bruns et_ al^., 1972, 1973, 1974). The one
important exception to this is that picloram will cause injury to potatoes
at concentrations of 0.001 mg/1 or lower (Ogg and Wapensky, 1969), and is
thought to be equally injurious to tobacco. Picloram is also among the more
mobile herbicides in soil water. There is therefore some risk to these
highly sensitive crops any time irrigation water is used from creeks down-
stream from areas in which brush control has been accomplished with picloram.
Other crops are not known to be sensitive at these rates, and levels of pic-
loram found in streams are probably a hazard only in connection with irriga-
tion of potatoes, because tobacco is seldom irrigated.
A discussion of effects of forest herbicides on water quality is not
complete without mentioning 2,4,5-T. This compound is probably more widely
used for conifer release and site preparation by aerial spray than all other
herbicides combined (much of the 2,4-D is applied by ground methods). This
herbicide has been in use for this purpose for more than 20 years, without
-------
recorded mishaps involving humans or wildlife from operational use. Since
1969, when 2,4,5-T and its contaminant 2,4,7,8 tetrachlorodibenzo-para-
dioxin (TCDD) were publicised as teratogenic, this herbicide has been very
closely scrutinized for harmful effects, with thus far negative findings
even though formal experimentation to this effect has been limited (Day et
al., 1975). There are very few pesticides whose record has undergone such
close investigation without some evidence of untoward environmental damage.
Ross has indicated that more is probably known about toxicological proper-
ties of 2,4,5-T than is known about any other pesticide. Despite this,
2,4,5-T ison EPA's list of pesticides considered to have rebuttable presump-
tion against reregistration. Silvex, another phenoxy herbicide containing
TCDD and which is also used as an aquatic herbicide, has toxicological pro-
perties almost identical to those of 2,4,5-T. It is used for aquatic weed
control in lakes and ponds at registered rates 20-2000 times as high as the
maxima observed after application in forests, with no buffer strips. Re-
ports of harmful effects to fish or wildlife from proper operational use of
this herbicide have not been found in this review, despite the confining
nature of such bodies of water.
Insecticides and rodenticides are animal toxicants of concern for their
direct effects on fauna in streams. Insecticides may cause injury to fish
at concentrations usually much lower than are required for damage from her-
bicides. There has been much evidence of fish kills with aerial application
of insecticides, DDT in particular, in forested watersheds (Kerswill, 1967).
There is also evidence that such applications need not cause injurious levels
Ross, Ralph. Director, Dioxin Implementation Program, EPA, Washington, D.C,
Address presented to the Western Society of Weed Science, Portland, Oregon.
March, 1976.
-------
of contamination if the material is applied under strict supervision so as
to keep it from falling directly into the creeks (Kerswill and Edwards,
1967; Tracy and McGaughy, 1975). Chlorinated hydrocarbons can produce ef-
fects through biological magnification. In this process, microscopic organ-
isms collect fat soluble compounds to higher concentrations than are present
in the water. As these organisms are used for food by larger organisms, the
consumers accumulate an increasing body load until the rate of intake drops
or until the rate of degradation equals intake at equilibrium. This mechan-
ism gives rise to considerably elevated concentrations of certain pesticides
in predatory fish and birds. Barring mortality, these high pesticide con-
centrations are reversible. At the worst, impacts of chlorinated hydrocar-
bons can have an effect on anadromous fish runs extending up to three years
(Kerswill, 1967). The worst offenders in this respect, DDT, aldrin,
dieldrin and heptachlor are not registered for use in forests. At best,
pesticides presumably have no effect whatever when concentrations remain be-
low the threshold of toxicity to the most sensitive organisms.
It is noteworthy that chlorinated hydrocarbons have been replaced for
forest insect control almost entirely by chemicals of the carbamate group,
(carbaryl) and of the organophosphate class, (malathion, fenitrothion and
trichlorfos). These compounds have very short biologically active lives,
and are remarkable for their broad spectrum effects on insects, with low
toxicity to mammals and sometimes to fish. Aquatic insects are very sensi-
tive to these materials, as are terrestrial target species. There can be a
substantial problem with aquatic insects and crustaceans when insecticides,
even of the selective group, are applied to open watercourses. With care in
application, however, Kerswill and Edwards (1967) and Shea (Dr. Patrick Shea,
25
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U.S. Forest Service, Pacific Southwest Forest and Range Experiment Station,
Berkeley, personal communication, 1976) have reported no adverse effect on
fish with the use of malathion and phosphamidon.
Ground applications of all classes of forest chemicals have tradition-
ally involved such small amounts of chemical at such great distances from
open water that their impacts on streams are of academic interest.
Relation Between Forests and Other Watersheds
The potential for water pollution from silvicultural use of chemicals
is very much influenced by the nature of the forest systems from which
water flows. Certain features of forest watersheds tend to increase the
likelihood of pollution from application of chemicals, and others clearly
decrease the risk of pollution. The typical features of forests that are
important in this respect are listed in Table 2.
Table 2. Features of forest watersheds that increase or decrease
the impact of stream contamination from silvicultural
activities compared to agricultural or other non-forest
watersheds.
Features That Can Increase Impact
1. Disturbed soils
2. Steep slopes
3. Upstream from most users
4. Frozen soil during spring
runoff
5. Skeletal soils
Features That Can Decrease Impact
1. Infrequent application
2. Continuous ground cover
3. Minimum surface runoff or
sheet erosion
4. High rates of dilution
5. Low proportion of area treated
6. High aeration
7. Active soil matrix
The general lack of mobility of the chemicals used in forests reduces
the significance of the physical features of forest watersheds that tend to
increase contamination; the difference between movement of a few inches
26
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or a few feet has little bearing on water quality in the absence of surface
runoff. Details of chemical behavior in the forest environment are dis-
cussed in Chapter 5 of this report.
In the Western states, forests are principally restricted to head-
waters. Water is essentially free of synthetic pollutants in the absence of
chemical applications. Elsewhere in the United States forests are inter-
mingled with farms and population centers. There is therefore more oppor-
tunity to pinpoint a source of pollutant in the West than in the East, but a
given input in the settled portions of the East is more likely to push an
existing pollution level above a hazard threshold.
Chemicals and Multiple Use Resource Values
Commercial forests produce a variety of products and benefits among
their many resource values. Wood products, water, wildlife, livestock graz-
ing and personal pleasure are the principal benefits to society.
Chemicals are used in forests principally for the management of commer-
cial timber, on which society has placed a premium value. Nearly all the
revenues accruing from the management of forested lands come from the sale
of wood products. The relation between timber and other resources is some-
what different on public and private timberlands, but commercial timber
growth is the dominant use on most commercial forest lands under deliberate
management. Under the circumstances, it is germane to consider the question
of whether the use of chemicals for the specific promotion of the timber re-
source compromises other values.
The resource value most likely to be influenced by the use of chemicals
appears to be that associated with recreational use. The specific feature
27
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of recreational use that may be jeopardized is the potential aesthetic or
psychological impact of damaged flora or fauna. Recreational users of for-
ests are often unaware that the intermediate objective of using the chemi-
cals is, in fact, to favor the growing of certain trees or that the long-
term outcome is often to restore and maintain species composition and stand
structure to forms more amenable to multiple use than exist at present. It
is not widely understood that the species appearing as targets are normally
those whose abundance have been inflated by human activity, and whose control
will restore or protect a prevalence of aesthetically desirable stands. Ad-
verse aesthetic effect is normally of brief duration, and bears no direct re-
lation to water quality unless managers are moved by public pressure to use
non-chemical methods of greater impact. Other resource values, including
wildlife and water, are affected by management goals but are not obviously
influenced adversely by the use of chemical tools for implementation.
The nature of the practices is basic to a discussion of resource val-
ues relative to a group of practices. As summarized earlier in this chap-
ter, fertilizers increase productivity of the whole forest ecosystem, her-
bicides modify the composition and structure of the plant communities and
animal toxins influence composition through management of consumption se-
lectivity and rate. Of these, herbicides have the least potential for caus-
ing direct harmful effects to aquatic fauna (see Chapter 5). Yet herbicides
initiate the restructuring of entire terrestrial ecosystems from which
waters flow. These changes are permanent as long as they are maintained by
a management system oriented toward timber production. They are not asso-
ciated with any particular impacts on water quality, although there are
28
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slight short-term increases in water yield attributable to decreased trans-
piration (Newton and Norris, 1976).
The long-term nature of forest responses to herbicides is of fundamental
importance in relation to other resource values. Changes in stand composi-
tion and structure influence every terrestrial organism that depends on
primary production. These, in turn, must therefore have some effects on the
aquatic community in relation to leaf and litterfall, insect populations and
other factors. Newton and Norris (1976) have outlined some of the principles
involved in evaluating the long-term ecological significance of using herbi-
cides .
The impact of insecticides on streams has resulted both from direct ef-
fects on fish, and from indirect effects through ingestion of contaminated
insects and other fish. In the case of chlorinated hydrocarbons, which tend
to accumulate in fat, there has been biological retention and magnification,
especially in lake populations (Muirhead-Thomson, 1971). In freshwater
flowing systems, the productive capacity of streams is affected only briefly
or not at all by low level contaminations by the transient insecticides
(Elson and Kerswill, 1966). There is evidence also that fish, as well as
insects, can develop resistance to toxic levels of pesticides through multi-
plication of resistant individuals. The observed recovery of stream product-
ivity after various kinds of disturbances suggests that there are several
mechanisms, including avoidance and resistant life stages, through which the
resiliency of the aquatic system prevents the prolonged depression of biomass
after pulse-type inputs. Observational data indicate that long-term losses
do not occur with non-persistent pesticides (Grant, 1967; Symons and Harding,
1974). A presumed exception would occur where decimation of smolts would
29
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reduce returns of anadromous fish in subsequent years. A serious resource
loss can occur, if streams produce contaminated fish, or valuable runs of
anadromous fish are reduced. In this sense, insecticides, especially chlor-
inated hydrocarbons, have the maximum potential for causing harm to aquatic
resources.
Trade-offs between resource values must necessarily enter into pre-
scriptions for water pollution control. It is beyond the scope of this re-
port to make specific value judgments regarding the relative importance of
each "commodity" produced by a forest. When recommendations are made re-
garding treatment alternatives, however, an attempt will be made to acknow-
ledge the consequences both in terms of aquatic and terrestrial resources.
ResQiency of Forest Ecosystems
Forested watersheds consist of stream systems influenced principally
by geology and the microenvironment conditioned by the forest cover. In
evaluating priorities for preserving one resource at the expense of another,
should such a question arise, it is appropriate to evaluate the duration of
response when both forest and aquatic systems are responding to chemical in-
puts.
Ecosystems are resilient. In the classical sense, succession of some
sort follows any disturbance to a forest or stream. The ultimate stage of
succession, the climax, prevails when each part of the ecosystem is replac-
ing itself in perpetuity. A very long time is required for climax forests
to develop, and it can be regarded as unlikely that extensive climax forests
have ever existed for long without disturbance by fire or some other agent.
Prevalence of subclimax or earlier serai communities is a natural phenomenon,
-------
and human activity has increased the percentage of forest areas in the ear-
lier serai stages. This relationship is similarly true of streams, but the
shorter successional period is reflected in the shorter life span of aquatic
organisms.
During the recovery of a forest from disturbance, changes are likely to
occur in forest streams. Total deforestation tends to increase streamflow
for several years, after which transpirational losses return to their former
levels. Continuous devegetation of a forest results in mineralization of
soil nutrients, for which the retention system has been impaired because of
reduced demands by growing plants, especially trees. Such effects presumably
can result from repeated application of non-selective herbicides or tradi-
tional farming practices. Regardless of the method, loss of the retention
system appears to be the key to nutrient loss, and the result is an effect
on water quality through nutrient enrichment (Likens et_ al_., 1970), or sil-
tation (Dissmeyer, 1973, 1974). Disturbances of this kind have not been a
part of practices developed for sustained yield of forest products. Because
the general intent of silvicultural use of chemicals is to enhance forest
productivity, primary producers are typically abundant enough to utilize
nutrients and water without serious losses of nutrients as the ecosystems
respond (Miller, 197-4). There is some evidence that immature second-growth
forest cover releases less nutrients than very young or mature stands (Leak
and Martin, 1975).
Resiliency of forest stands also has an influence on forest stream
temperatures. Water quality is a function of temperature as well as chemi-
cal composition, and streamside vegetation has a substantial effect on water
temperature (Brown and Krygier, 1970). Choice of methods for vegetation
31
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control influences streamside cover. Aerial application of selective herbi-
cides leaves some streamside vegetation even when buffer strips are not
specified. Riparian species typically have rapid growth rates in early
years and shade reestablishes itself quickly over small streams. Both me-
chanical and chemical control of forest vegetation can be effected with min-
imal effects on such vegetation. If either has an effect on streamside vege-
tation, however, the recovery of vegetation after application of herbicides
tends to be more rapid than after the more complete suppression which results
from scarification. Scarification (and its effects) are easier to monitor,
however, and accidental treatment of streamsides is more likely with aerial
applications of herbicides than with scarification. Whether chemical brush
control immediately adjacent to streams has a measurable effect on water
temperature has not been studied, although change in shade has predictable
effects. With either method, it would appear that the effect of partial con-
trol of streamside brush would have a substantially lower long-term effect
than would the permanent removal or reestablishment of coniferous cover.
That is, the management goal itself likely exerts an influence greater than
that of the practice of implementation.
Effects of insecticides on insects and crustaceans can have subsequent
effects on fish under some circumstances. Aquatic insects make up a sig-
nificant proportion of fish diets at certain times of the year. Eradica-
tion or reduction of such species has the potential for a sharp reduction in
certain fish foods. This may lower carrying capacity in the absence of al-
ternative food supplies, and persistent insecticides may biomagnify so as to
cause injury to fish (Sprague et al., 1971). Because of the widespread na-
ture of some insecticide operations, there is some possibility that a pulse
-------
contamination of chlorinated hydrocarbons, will be followed by relatively
slow re-invasion (Muirhead-Thomson, 1971). There is also minimum opportunity
for fish to escape to other stream branches or main channels of lower con-
tamination levels. Thus, moderate contamination with a persistent insecti-
cide, on a widespread basis, can reduce carrying capacity for a season or
more, although Tracy and McGaughy (1975) observed no reductions after use of
DDT. Severe contamination by many insecticides will cause fish mortality
directly, but concentrations of short-residual insecticides high enough to
cause heavy insect mortality on a widespread basis are unlikely to harm fish
even with narrow or negligible buffer strips when there is close surveillance
of operations (Tracy and McGaughy, 1975; Kerswill, 1967).
In summary, insecticides of both organophosphate and carbamate groups
tend to have pulse effects on streams, with principal impacts focusing on
aquatic insects and crustaceans. The long-term effect of a contamination
level that might be associated with a non-buffered application by aircraft,
i.e., up to .1 mg/1 for one day, would be limited to a brief decrease in
fish production, lasting less than one year. Because of the lack of bio-
magnification, it is unlikely that higher trophic levels or organisms would
eventually carry potentially harmful residues of insecticide. Organochlo-
rine insecticides, however, have the potential for appearing in streams over
an extended interval after application, leading to a more or less chronic
exposure. Although it appears unlikely that the long term productivity of
any given stream will be seriously reduced by a single application at forest
use rates, harmful concentrations could remain in fish and consumers of fish
beyond the year of application.
33
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Herbicides are generally low in toxicity to insects, crustaceans and
fish relative to insecticides. There is no evidence that measurable ad-
verse effects to fish occur with broadcast applications of presently regis-
tered herbicides, nor that other wildlife using the water is likely to be
affected. Because of the lack of initial observable effect on the aquatic
ecosystem, the principal resource value potentially jeopardized by herbi-
cides relates to irrigation; the aquatic ecosystem itself is resilient enough
to accommodate a substantial contamination without major harm being done.
To summarize the comparative generalized effects of insecticides and
herbicides on forest resources, the following statements appear to be con-
sistent:
1. Aerially applied insecticides of short residual life may reduce the
impact of defoliating insects on forest trees for 2 years or more, and per-
haps several decades, if applied to forests not yet severely defoliated, and
if the insect epidemic is not on the verge of collapse. Impact on streams
without buffer strips, but where application to open water is avoided, risks
a reduction in carrying capacity of streams for part of one year, but ap-
pears to have no other adverse effects on the aquatic system; the degree of
impact varies among insecticides. Treatment with buffer strips reduces the
contamination levels in streams, hence minimizes degree and duration of
lost productivity of aquatic ecosystems.
2. Aerially applied organochlorine insecticides have short-term effects
on terrestrial insect communities similar to that of the short-lived insect-
icides. They have a longer effect on both terrestrial and aquatic species,
which, however, can be expected to recover. Ordinarily, the effects on
primary producers is similar - negligible - to those of carbamates and
-------
organophosphates. Effects on stream biota are more persistent when major
contamination occurs. Reduction in stream productivity in such instances
may last a year or more, depending on the nature of the stream system and
the proportion of watershed treated.
3. Surveillance of application will minimize insecticide deposit in
streams, hence toxic hazard, regardless of chemical used.
4. Application of herbicides for conifer release, or to prepare for
establishment of conifers, causes a change of forest type that persists un-
til the stand is removed. In the Pacific Northwest, this usually means re-
storation of the species that was prevalent before development of the plant
community being treated. Because the conifers becoming dominant as the re-
sult of treatment tend to remain dominant, ecosystem resiliency does not re-
store the system to its pre-treatment status. Since an increase in conifer
production is the objective of treatment, this particular ecosystem re-
sponse precludes the requirement for additional major disturbances until the
next cycle of harvesting. With the exception of apparently minor changes in
stream habitat due to increased short-term radiation resulting from hardwood
defoliation, aquatic ecosystems do not appear to be influenced either in
composition or productivity, regardless of whether buffer strips are used.
Long-term shading will increase as conifers become dominant, and changes in
litterfall into streams will occur.
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Problems and Practices Entailing Aerial Applications
of Chemicals, and Alternatives
Forest managers confronted with pest or fertility problems often can
choose among several alternatives that will support long-term objectives.
Most forested areas have never received the direct application of any sil-
vicultural chemical, and many areas in all likelihood will not be treated
in the forseeable future. The following summary will outline the most
common problems for which chemicals are generally used. Based on data avail-
able in 1976, the various solutions to the problems will be listed with
their relative costs per unit of effectiveness and relative impacts on water
quality.
NITROGEN DEFICIENCY
There are basically two approaches for improving nitrogen nutrition on
forest lands. One of these, widely tested and utilized, is the aerial appli-
cation of nitrogen fertilizer. Urea is the form of nitrogen generally used
because of the relatively low cost of chemical and application. A potential
alternative is the use of nitrogen-fixing plants as a cover crop. The latter
method has not been utilized in any major industrial applications, but de-
serves more attention in view of low cost and prolonged increment of nitro-
gen in large quantities.
As of 1976, prices for urea nitrogen are in the range of $20-30 per hun-
dred pounds elemental nitrogen, including application and overhead. Responses
can be expected on N-deficient sites for five or more years after applications
of 200 pounds N per acre (220 kg/ha). The decrease in response with time
is apparently attributable to ecosystem utilization of the added nitrogen;
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the findings of Moore (1975) and others (Klock, 1971; Maleug et_ al., 1972)
demonstrate that very little of the nitrogen leaves the site in leaching
and streamflow. Thus, addition of nitrogen fertilizer appears to add to
ecosystem nutrient capital without having appreciable effects on long-term
stream quality.
The use of nitrogen-fixing plants involves a complex technology. In
the Pacific Northwest, Newton et_ al_., (1968) found that red alder could fix
approximately 300 pounds of nitrogen per acre per year (330 kg/ha). In
order to capitalize on the added fertility, however, Douglas-fir must be
free of overhead competition, and the simultaneous establishment of alder
and Douglas-fir is seldom attainable. Some nitrogen can be realized without
serious suppression of conifers if the dominant alder is sprayed with 2,4,5-T
as a release treatment between the fourth and sixth year after establishment
(Newton, M., Oregon State University, unpublished data), or if the fir is
planted substantially before alder (Newton et_ al^., 1968). Release is less
essential if very large western hemlock seedlings are planted. The presence
of heavy alder competition during the establishment years of either species
causes a long-term loss of growth, however.
There is fragmentary evidence that Scotch broom, a leguminous shrub, is
a vigorous nitrogen fixer that can be managed so as to fix nitrogen while
not suppressing conifers (Newton, M., unpublished data). Broom is regarded
generally as a noxious weed, but has a growth habit that does not threaten
established Douglas-fir plantations if established two or more years after
planting of conifers. Being intolerant of shade, it has the potential for
fixing nitrogen before being suppressed out by conifers, without herbicide
release. Should broom overtop a slow-growing plantation, it is very
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sensitive to dormant applications of 2,4-D ester in oil. Other legumes,
black locust and lespedeza, in particular, have been used for nitrogen fix-
ation in the rehabilitation of coal spoils in eastern United States. These
legumes also must be planted long enough after the crop species so that they
do not suppress the species forming the forest crop.
In any program involving nitrogen fixation, certain requirements must
be met for the fixer to do its work effectively. Nitrogen fixation re-
quires an abundance of phosphorus, and adequate quantities of cobalt, zinc,
manganese, nickel and iron. Soil acidity must be in suitable range for
nitrogen fixing species being used, and adequate infection rates of symbiont
must be on hand prior to nodulation. The growth habit of the fixer must be
matched to the crop species to prevent suppression, and the sensitivity of
the nitrogen fixer to herbicides must be understood before it is introduced
into a plantation. Many of the nitrogen fixers have the potential of becom-
ing serious weeds as well as making valuable and energy-saving contributions.
Nitrogen fixation is an energy consuming process. Fixation is not an
automatic phenomenon in the presence of nodulated plants. Newton et al.,
(1968) observed that fixation tends to decrease in the presence of adequate
levels of nitrogen. Red alder fixes nitrogen to a considerably higher
equilibrium level than snowbrush ceanothus, but both appear to fix at some
rate in proportion to the degree of nitrogen deficiency.
In summary, nitrogen can be applied either by chemical fertilizers or
by biological fixation. Nitrogen fixation does not necessarily minimize the
use of chemicals; it does entail different chemicals. Fixation often re-
quires phosphorus, minor elements and herbicides. It also demands an exact-
ing comprehension of ecological programming so as to gain nitrogen without
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losing the crop species. Under ideal circumstances, biological fixation can
provide more nitrogen per dollar than can nitrogen fertilizer. It will un-
doubtedly be many years before the technology of cover crops for conifers
becomes operationally feasible on large acreages. Choice of procedure is
not likely to have a major impact on water quality. The higher soil nitro-
gen levels associated with biological fixation will probably be offset by
lack of direct application of chemicals to water.
PHOSPHORUS DEFICIENCY
Until recently, there was no commonly used remedy for phosphorus de-
ficiency other than addition of phosphorus fertilizer or soil drainage in
certain wet lands. There is now some evidence that certain mycorrhizal fun-
gi may enhance availability of phosphorus (Marks and Kozlowski, 19?3).
Liming of acid soils and application of sulfur to alkaline soils can also
increase availability of the existing phosphorus supply (Buckman and Brady,
1960).
MOISTURE
Plantation establishment on droughty sites is often restricted by her-
baceous vegetation. Newton (1964) reported that herbaceous cover accounted
for 85 percent of the total spring and summer losses of moisture in a clay
loam soil in western Oregon. Although evaporative losses are relatively
greater on coarse textured soils, drought stress can be reduced to tolerable
levels on a wide variety of forest sites by controlling herb cover (Newton,
1970).
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Control of herbaceous weeds can be accomplished either by chemicals or
mechanical equipment. Grazing has been attempted, but stocking levels com-
patible with seedling survival do not provide for adequate removal of trans-
pirational surface (Black and Vladimiroff, 1963). Chemicals include those of
the s-triazine group and dalapon for grass control, and 2,4-D for broadleaf
weeds. Application rates for the triazines range from two to four pounds
of active ingredient per acre; dalapon is applied at 3.4 to 8.5 Ibs/acre (3-8
to 9.4 kg/ha) of active ingredient as the sodium salt; 2,4-D is applied at up
to 4 Ibs/acre (4.4 kg/ha), usually as the low-volatile ester. These herbicides
are generally not applied to disturbed soil except in Christmas tree plan-
tations. They may be applied either by ground or aerial equipment. Preven-
tion of water pollution may be achieved by reducing application to open
water and by eliminating tillage. Precision of application by aircraft can
be improved by addition of drift-reducing adjuvants, but any procedure that
increases droplet size may reduce the effectiveness of herbicides that act
through foliar activity.
The effectiveness of chemical weed control is attested by its wide ac-
ceptance in the Pacific Northwest, especially in Christmas tree operations.
The cost of chemical weed control in that region ranges in the vicinity of
$15-30 per acre, ($37-75/ha) in return for which plantation survival increases
from a range of nil to 50 percent to a range of 50 percent to nearly perfect.
That is, weed control has made possible the establishment of plantations in
one operation on sites that have heretofore been left nonstocked.
Mechanical weed control entails the use of a variety of devices calcu-
lated to suppress vegetation long enough to permit seedling establishment
prior to recovery of weed cover. Conventional ploughing and disking prior
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to summer fallow and fall disking is one common method. This procedure will
provide reasonable survival of planted seedlings; success is enhanced by
the use of residual herbicides to prolong the weed-free period. Operational
costs are similar to those of chemical weed control when chemicals are not
used, and survival tends to be somewhat lower (Newton, 1970). This proce-
dure is limited to sites that have been previously cleared of stumps and
rocks.
Other methods have been used in forest situations. Bulldozing to
scarify sod is one method used occasionally in the Pacific Northwest; roller
choppers and shearing blades have been used in southeastern United States for
a variety of weed situations. Mechanical weed control methods do not bury
all seeds deeply, and annual weed communities are reestablished with great
rapidity unless surface soil is removed. Thus, mechanical methods are not
generally recommended for herbaceous weed control because of the short term
of their beneficial effect on the plantation. Surface soil disturbance also
increases movement of silt into streams. Costs of scarification in grassy
areas range somewhat higher than chemical control; roller choppers are ap-
proximately comparable to chemical control in cost, but are not generally
used in herbaceous weed problem areas. Cost per unit of survival is least
for chemicals by a substantial margin in severely droughty areas, with ad-
vantages decreasing as summer moisture becomes less critical.
Hand scalping, the process of removing a circle of weeds from a plant-
ing spot during the process of planting, has been used extensively. This
practice is of marginal value on severely droughty sites, and is labor
intensive, hence costly. The use of spot applications of herbicide toward
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the same end is more effective and less costly; spot spraying leaves a
mulch of dead material to protect soil from evaporative stress.
Water quality can be affected by mechanical herbaceous weed control.
The combination of tillage and chemical weed control for several years, as
practiced in some northwestern Christmas tree plantations, leaves opportun-
ity for development of erosion pavements, with attendant siltation. When
done without cultivation, soil structure remains intact, and erosion is much
diminished. An analogy to no-till farming is appropriate.
On flat ground, the use of heavy equipment for forest weed control with-
out concurrent use of chemicals probably has very little effect on water
quality as long as soil is only lightly disturbed. Machine operation can
compact soil and lead to decreased infiltration (Froelich, 1974). But un-
disturbed forest soils usually demonstrate excess ability to absorb rain-
fall, and small, temporary decreases in infiltration capacity are apparently
possible without causing surface runoff under Pacific Northwest conditions.
The short period of weed control by light scarification leads to rapid
stabilization of soil surfaces soon after the onset of rains. Herb cover
protects against the formation of an erosion pavement. Siltation can oc-
cur if heavy equipment operates on steep slopes, in creeks, or pushes de-
bris into channels. Various states already have prohibitions against these
practices. The chief shortcomings of the method where it is legal, are its
lack of effectiveness when applied with minimum impact on soil, and its
destructiveness on soils and watersheds when applied for maximum clearing.
In summary of herbaceous weed problems, chemical weed control is the
most cost-effective method in areas of seasonal drought. When used alone,
there is negligible deposit of herbicide in water, and siltation is not
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increased. When used in combination with tillage, siltation can occur if
weed control is maintained for a period of several years. In view of the
tendency for most herbicides to adhere strongly to soils of high organic
content, (Moore and Norris, 1974) a substantial movement of surface parti-
cles in forest soils would likely cause the movement of a certain amount of
adsorbed herbicide into the stream. The effect of such pollution is un-
known, but appears to be slight. Mechanical methods are of some utility,
especially in areas where droughtiness is of marginal intensity. Mechanical
methods have a maximum impact on soils, perpetuate the herbaceous weed com-
munity and risk the direct deposit of sediment and debris in stream channels.
Hand scalping is not a satisfactory substitute for chemical or mechanical
weed control except in very favorable site conditions. All methods, applied
effectively, lead to development of a forest cover, with its attendant long
term implications for high water quality.
SHADE AND LITTER PROBLEMS-BRUSH AND HARDWOOD COMPETITION
Undesirable woody plants constitute the largest group of pests affect-
ing timber values in the United States. Walker (1973) reported that some 300
million acres of forest land (60 percent of the commercial forest resource
area) were supporting less than 70 percent stocking in desirable species be-
cause of weed problems; over 100 million acres are either poorly stocked or
nonstocked. Weed trees and shrubs occupy many of these sites in a semi-
permanent fashion (Newton, 1973) and restoration of productivity will neces-
sarily entail the removal or control of large areas of brush and weed trees.
Specific operations involving woody plant control are stand improvement, re-
lease and site preparation.
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There are several widely used methods for treating brush and weed tree
problems, including chemical, non-chemical approaches, and combinations of
chemicals with mechanical procedures and fire. These methods produce dif-
ferent effects, depending on the situations in which they are used, and
differ in cost. The selection among alternative practices is dependent on
the specific nature of the problem. Water quality has not been an impor-
tant factor in selection, and there have been few, if any, reports showing
negative impacts on aquatic systems associated with chemical or mechanical
weed control. In recent years, there has been an increase in the use of
fire in forest rehabilitation. Fire has been identified with increases in
surface soil movement, in some instances associated with development of a
hydrophobia layer at the surface.
Fires used in rehabilitation are planned for high intensity and short
duration. High soil surface temperatures for long periods are avoided de-
liberately. Chemical treatment for pre-burn desiccation is a part of fuel
preparation that permits burning when large fuel is still moist and adjacent
ownerships are low in flammability. Roberts (1975) has reported that reve-
getation occurs very rapidly after brushfield fires in the Oregon Coast
Range. Her work suggests that light burns in nitrogen-rich sites are un-
likely to leave soil surfaces vulnerable to excessive acceleration of soil
movement. Herbicides, such as phenoxy herbicides at rates up to four
pounds per acre, picloram at one pound per acre, and the toxic product
dinoseb at up to five pounds per acre, are essential to allow burning when
adjacent areas are low in flammability.
Chemical site preparation entails the use of herbicides alone for pre-
planting treatment of brush. Phenoxy herbicides, picloram, amitrole and
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ammonium ethyl carbamoyl phosphonate are used for this purpose. Of these,
the latter two are remarkable for their low impact on aquatic systems, but
their activity on woody plants is somewhat restricted. Glyphosate, at pre-
sent unregistered, shows substantial promise for this use.
Felling of weed trees is an approach to control that has received wide-
spread use. Felling alone provides adequate composition control and release
where existing stands have a sufficiently large component of desirable stems.
Sprouting stumps tend to compromise plantations established at the time of
felling, however. Chemicals such as phenoxy herbicides and picloram are
used to treat stumps to prevent sprouting. The felling of large cull trees
also has a severely injurious effect on residual desirable trees. Eastern
hardwoods, in particular, are easily scarred. Disease control considera-
tions in stand improvement operations favor chemical treatment of standing
trees because the procedure avoids such damage in felling. Girdling can be
substituted for chemical treatment in species with low sprouting potential,
at considerable extra expense over that of injection (Beavers, 1957). In
the only major study of water pollution associated with tree injection,
Norris (1974) reported no increase in streamwater content of arsenic when
entire watersheds were treated with organic arsenicals by injection for pre-
commercial thinning. The same pattern can be expected with phenoxys and
picloram. Even though very large areas of commercial forest land are in
need of stand improvement, a choice between injection and felling or gird-
ling is unlikely to have a measurable effect on water quality.
Aerial application of phenoxy herbicides, 2,4,5-T in particular, is a
prevalent method of providing release. Applications are scheduled from
early spring through fall in the Pacific Northwest, in summer in the
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Southeast, and in early August in New England (Fitzgerald et_ al_., 1973;
Gratkowski et_ al_., 1973; Newton and Smith, 1976). Chemical release is usu-
ally done by helicopter, and the herbicide may be applied either in water
or diesel fuel. An increasing acreage is being treated in the South by air
blast equipment.
Felling has been used for forest release operations. Costs for re-
lease by aerial application of 2,4,5-T are approximately one third of those
of hand felling. Damage to suppressed trees by falling hardwoods is a major
problem and individual removal of hardwood crowns from bent-over conifers is
a major contributing cost in hand release work.
Water quality has been monitored extensively in the Pacific Northwest
to determine amounts of herbicides reaching water supplies during aerial
application of herbicides. The use of buffer strips and close surveillance
of applicators are the principal methods of pollution control. Patterns of
herbicide deposit observed in streams and their behavior are discussed in
detail in Chapter 5 of this report.
Treatment of brush in buffer strips by non-chemical means is presently
not generally feasible in the steep forested topography characteristic of
western United States. The use of mechanical equipment on the occasional
gentle topography increases both cost and risk of siltation. Hand felling
is possible, but costly and ineffective in reducing sprouting. The stabi-
lity of untreated brushfield communities is well documented (Newton, 1973;
Newton et_ al., 1968; Gratkowski et_ al_., 1973) and leaving non-stocked brush
untreated essentially deletes those areas from the timber resource base.
The consequences of various streamside management schemes are important con-
siderations in the choice of practice in management of buffer strips.
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DEFOLIATION BY INSECTS
Insect outbreaks occur in patterns that differ substantially from vege-
tation problems. Epidemics often cover large contiguous areas or a high
concentration of foci within an outbreak area.
Aerial application of insecticides is a standard procedure for minimiz-
ing insect damage. The prescription of aerial broadcast application of
insecticides therefore entails the risk of pollution on major stream sys-
tems. Nearly all insecticides currently used for aerial application of
forest insects in the United States are of the organophosphate or carbamate
groups. Applications are sometimes repeated over extensive areas to con-
trol spruce budworm in Maine and eastern Canada, but seldom elsewhere in
the United States. In all areas, use of buffer strips is the prevalent
method of pollution control.
Alternatives to chemicals include biological insect control agents,
predatory insects, attractants and silvicultural control of insect habitat.
The sterile male technique has not been adapted operationally to forest
insects. Integrated control systems entail combinations of chemical,
biological and silvicultural control techniques.
Biological insecticides include Bacillus thuringiensis and nuclear poly-
hedrosis virus suspensions. These are applied in the same manner as insect-
icides, with substantial effectiveness on several insect species. Both are
in the emerging stages of technology, and a virus has been registered for
use on the Douglas-fir tussock moth. Their advantages include high speci-
ficity for target insects and lack of residue; their disadvantages include
high cost, occasional failures in maintaining culture viability, and amount
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of lead time needed to have adequate fresh, culture on hand for operational
treatment of large epidemics. The potential effects of biological agents on
water quality have not been investigated at the same level of intensity as
chemical pesticides, and consequences to aquatic systems are unknown, but
apparently minimal.
The use of predatory insects in the classical biological control sense
can be shown to be effective on a local basis. Logistical problems and ex-
pense are likely to limit operational use of this technique on large scale
outbreaks.
Attractants have the potential of improving detection of major out-
breaks and of creating a sink for breeding insects during incipient stages
of epidemic development (Radinsky, 1963). The attractants are chemical
pheromones that are set out in stations distributed throughout potential
epidemic areas. Amounts of chemical are small, and the chemicals used are
not regarded as pesticides. Operational utility of this concept is regarded
as promising but no major outbreaks have been controlled at this time on the
basis of its use exclusively.
Silvicultural control of insects is a time-honored system that has sev-
eral major shortcomings in the treatment of present-day epidemics. This
method involves the maintenance of stands in a state of composition, stock-
ing and vigor so that insect populations remain within endemic levels. The
same procedures that are used for management, i.e., thinning, composition
control and high vigor management, are also normally effective means of im-
proving the economic outlook for the stands themselves.
Limitations of the silvicultural methods are inherent in the nature of
the resource to which they need to be applied. This approach requires the
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intensive management of extensive contiguous areas of forest. Epidemics of
the major defoliating insects are often focussed in areas that are largely
inaccessible, or at least impossible to place under management quickly.
Outbreaks of the Douglas-fir tussock moth and spruce budworm have a tendency
to occur in extensively managed stands, or those in which no management has
been initiated. In the former, particularly, the silvicultural requirements
for avoiding outbreaks are only now under investigation. In the latter,
there is evidence that composition favoring spruce as a greater component
than true firs, and maintenance of all stands in a vigorous growing condition
minimizes budworm damage. In much of the spruce-fir forest region, reserves
of overmature stands (in reference to budworm activity) are great enough so
that many years will elapse before young, managed stands dominate the re-
gion. The scale of operation needed to implement silvicultural control on
the eve of an impending epidemic reduces its value for short-term use. In
the long run outlook, however, silvicultural management of stands vulnerable
to defoliators can be expected to reduce outbreak scale and intensity.
DAMAGE BY RODENTS TO DESIRABLE TREE SPECIES
Rodents and other wildlife cause major damage to forest regeneration.
Methods used to minimize losses include direct control of animals with ro-
denticides, protection of seedlings with physical barriers, use of repel-
lants, vegetation management to control animal habitat and the planting of
species of low vulnerability to animal damage.
Rodenticides include strychnine alkaloid, endrin and zinc phosphide.
Of these, only endrin is applied by aircraft, and only as a seed treatment.
Sodium fluoroacetate (compound 1080) was used for this purpose, but is no
longer registered.
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Rodenticides are prepared in baits. They are distributed so that tar-
get animals will be attracted without causing major harm to nontarget spe-
cies. Quantities of toxicants are extremely small. The most widespread of
these is endrin, used for treating conifer seed in aerial seeding opera-
tions in the Pacific Northwest. Endrin is applied to seeds in a concentra-
tion of .5 percent of seed weight. Treated seeds are distributed at the
rate of one-half to one pound per acre, with attendant distribution of
endrin at the rate of .0025 to .005 pound per acre, (3 to 6 grams per hec-
tare). Endrin has been recovered from streams after such applications at a
maximum concentration of 0.00006 mg/1, decreasing to the detection limit of
0.000001 mg/1 in 10 days (Moore et_ al_., 1974). Because of high risk of
failure, aerial seeding is losing popularity, and the use of endrin has de-
creased. Other rodenticides are not applied broadcast, and have no direct
access to water supplies. In general, aerially applied rodenticides do not
constitute an appreciable toxic hazard to aquatic systems or water supplies.
Their future use will likely be restricted to reforestation of burns for
which planting stock is not available, and inaccessible steep slopes.
Physical barriers to protect seedlings have come into large scale use
in the Pacific Northwest. Plastic tubing and stakes are placed on each
seedling after planting. Large rodents, deer and elk are prevented from
causing mortal injury to seedlings. Costs per acre for establishment and
protection are very high, but this method has gained acceptance because of
its dependability, and the wide range of animals from which it offers pro-
tection.
Chemical repellants include a zinc complex (ZIP), tetramethylthiuram-
disulfide (TMTD) and a recent development of a sulphurous compound made from
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eggs (BGR). These materials may be applied to seedlings in the field or
nursery by locally applied ground sprays, and do not represent a hazard to
water quality. TMTD and BGR have been applied from aircraft in research
studies, but with varying effectiveness in preventing animal damage.
Control of animal damage has been demonstrated in several studies of
habitat control. Borrecco, 1973; and Borrecco et_ al_., 1974; have shown
that vegetation management with herbicides can have a marked temporary in-
fluence on the use of a regeneration area by certain wildlife. Herbicides
specific for grasses and broadleaf weeds each had a role in the modification
of habitat, and the effect on animal use was related to duration of pre-
ferred species control. This approach is clearly not a non-chemical method,
but substitutes chemicals with tolerances established in human food in place
of highly toxic rodenticides. The method is ecologically logical because
of its reduction of carrying capacity for offending animals. The herbicides
involved, atrazine, simazine, dalapon and 2,4-D relate to water quality as
outlined under the discussion of moisture dificiencies attributable to her-
baceous weeds. Treatments for animal damage control also provide seedling
growth response, reducing vulnerability to future injury.
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CHAPTER4
CRITERIA FOR UMTIING CONCENTRATIONS
OF CHEMICALS IN WATER
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CRITERIA FOE LIMITING CONCENTRATIONS
OF CHEMICALS IN WATER
According to the Title I amendments to the Federal Water Pollution
Control Act, Sec. 101, the national goals relating to pollution sources are
repeated:
1) that the discharge of pollutants in the navigable waters be elimi-
nated by 1985.
2) that, wherever attainable by July 1, 1983, an interim goal of water
quality be achieved so as to provide for the protection and propagation of
fish, shellfish and wildlife, and provide for recreation in and on the water.
3) a national policy was also established that the discharge of toxic
pollutants in toxic amounts be prohibited.
The purpose of this particular set of guidelines for pollution control
is to enable conformance with these goals and this policy by eliminating
harmful effluent arising from non-point sources related to use of silvicul-
tural chemicals. Of critical importance in the achievement of this objective
is the identification of those harmful effects to be avoided. Once harmful
effects are perceived, target levels of water quality can be established
below which social and biological systems are undamaged.
Because the non-use of all silvicultural chemicals is not in the best
interests of the nation's forest resources, maximum concentration limits
must be set for chemicals in water that insure both safety and conformance
with the national goals and policy. And they must not force land managers
to resort to demonstrably harmful substitute practices. That is, the
cleanest possible water and good forest management are both desirable. The
purpose of this section is to propose l) a system of classifying streams and
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use patterns in relation to water quality objectives, and 2) within this
approach, express concentrations and conditions representing upper limits
of allowable concentrations while defining where they are tolerable and
under what circumstances stricter standards are necessary. These levels
are not intended as guides for irrigation systems and impoundments in which
higher levels of herbicide may be required for aquatic weed control.
Maximum concentrations for some of the silvicultural chemicals are
listed in the 1975 draft edition of Quality Criteria for Water (QCW), pro-
posed by the Environmental Protection Agency. Several of the most important
chemicals used in silviculture, including the most controversial, 2,4,5-T,
are not discussed, however. The chemicals that are mentioned are assigned
single numbers reflecting an upper limit of concentration, regardless of the
system in which the pollution is occurring.
This document proposes an expanded treatment for certain chemical cri-
teria in relation to forested watersheds, and offers criteria for all silvi-
cultural chemicals, including some covered by QCW. The group of criteria
proposed here contains allowances for variation in stream size and use. The
approach combines biological and statistical concepts to estimate thresholds
of harm to ecosystems. These estimates are based on the nature of the eco-
system, the substances to which organisms in the system are exposed, and the
form, magnitude, and duration of exposure. The assumptions and value judge-
ments are given.
A listing of recommended tolerance levels, and conditions under which
tolerances vary, is given for all registered pesticides and fertilizers
likely to be applied so as to reach forested waters as the result of silvi-
cultural use. Potential synergism among chemicals is not considered.
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SiIvicultural chemicals are found at very low levels in streamwater, and
two or more chemicals are seldom used simultaneously. A revision of this
approach may "become necessary as intensity of forest management increases.
A brief explanation of toxicological principles and of the data on each
chemical will follow.
Relation Between Dosage and Response
Exposure of organisms to toxic substances results in the uptake of some
of the substance. The amount taken up in relation to body weight determines
the degree of effect in a quantitative relationship. This relation may be
linear or non-linear, depending on mode of action.
Acutely toxic substances have more of an effect when a given amount is
administered as a single dose than when divided into numerous small doses
over a period of time. Mortality is a standard index of response. Chron-
ically toxic materials act in the reverse manner, and cumulative effects on
behavior, reproduction or oncogenesis are some indicators of exposure.
Sublethal effects of chronic exposure may be investigated in terms of re-
actions of eggs or atypical reactions of fish to their physical environments
(Muirhead-Thomson, 1971).
The relation between dosage and response is expressed differently in
the above two classes of chemical. Acutely toxic chemicals characteristically
produce a log-linear dosage response within a finite range. Below this
range, the organisms deactivate the chemical without permanent injury; above
this range, all individuals are dead and no further response can be tested.
Chronically toxic materials do not follow the same pattern. Low levels of
continuous exposure result in cumulative deposits in vital processes,
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leading to manifestation of long-term difficulties in general metabolism,
reproduction, or tumor initiation. Chronic exposure to acute toxicants at
subacute levels can elicit a chronic reaction, usually reversible when
exposure ceases. Thus, both exposure rate and duration of exposure are
important in evaluation of toxic hazard. The former tends to be of para-
mount importance with acutely toxic chemicals, the latter with chronically
toxic substances.
The term "acutely toxic" should be distinguished from "highly toxic".
The former refers to a type of toxic action, while the latter refers to de-
gree of toxicity. Most herbicides used in forestry are of low to medium
toxicity, and are of the acutely toxic group. The insecticides other than
chloroniated hydrocarbons are more variable in mammalian toxicity, but
are still in the acutely toxic category. The chlorinated hydrocarbons may
be either of the acutely toxic or chronically toxic class, and also have a
wide range of mammalian toxicity.
The "No-Effect" Level of Toxic Chemicals
Direct harm to organisms results from exposure to toxic chemicals only
when sufficient toxin enters biochemical systems to interfere with critical
functions, i.e., the "threshold" dosage is exceeded. Despite the extreme
toxicities of some chemicals, harm is not likely to occur when the first
molecule of toxin enters the organism. The reason for this is that cells
are equipped with many functional molecules at each link within each meta-
bolic pathway. For many metabolic functions, there are several pathways
and many sites within each pathway that can keep the organism functioning
when one biochemical system or site is temporarily blocked (Loomis, 197/4).
55
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Furthermore, all toxicants are sorted, inactivated or detoxified to some
extent by metabolic action, and surviving organisms usually emerge from
sublethal exposure to acutely toxic substances without permanent injury or
harmful residue. This expectation is valid for most chemicals used in forest
operations, because of their low toxicity to animals and moderate to rapid
decomposition. This generalization does not hold for chronically toxic
materials, of which none except rodenticides are registered for aerial ap-
plication in forests.
Demonstration of precise "no-effect" levels of toxic exposure poses
social, biological and statistical difficulties. It can always be argued
that humans remain untested, hence are subject to uncertainties resulting
from testing with other mammals. This uncertainty will remain a social
problem in administration of any allowable-level guidelines, and is the
basis for using wide safety margins when extrapolating from tests to regula-
tions. Resolution of this problem is beyond the scope of these guidelines,
but some guides for safety factors are presented below for inspection.
In the biological estimation of "no-effect" levels, it is necessary to
use measures other than traditional acute toxicity tests to determine expo-
sure rates leading to weight loss and other symptoms. In standard tests,
mammalian toxicity is determined according to a median lethal dose (LD_Q);
fish sensitivity is gauged by a median lethal concentration in water (LC,-n).
The variation among species, and among individuals within species, are
often examined for acute toxicity with traditional statistical methods for
predictive purposes. Typically, symptoms within a test population of org-
anisms show up according to a cumulative frequency distribution as in Figure
1. The distribution of responses illustrated in Figure 1 is a translation
56
-------
LU
O
I-
2
100
a:
01
UJ
LU U.
> U.
0
i i
MEASURABLE
RESPONSE
THRESHOLD
DOSE
MORTALITY
LD 50
ID
a
O.I 10 1,000 100,000
ABSORBED DOSAGE,
MG/KG BODY WEIGHT
Figure 1. Typical dosage - response curve for an animal population fed a
toxic substance. Note that dosage is "based on units of toxi-
cant per unit of body weight. Threshold (no effect level) is
the dosage below which organisms detoxify chemical as fast as
it is absorbed. These curves are transformed normal distribu-
tions. In laboratory tests, slopes of curves vary among
species (Muirhead-Thomson, 1971).
of a normal distribution of incremental responses to incremental dosages of
toxic substances, (Figure 2). In conducting tests for population responses,
samples of variable individuals are used, leading to an assumed bell-shaped
normal distribution. Increasing the number of samples can increase the
precision of estimate of median response point, but cannot identify either
"no-effect" or "100-percent effect" levels exactly, regardless of sample size
(Figure 2).
The traditional use of the normal distribution in tests of acute toxi-
cants has been unsatisfactory. Because a normal distribution cannot concept-
ually show a zero expectation of responses, an infinite number of samples
57
-------
still cannot predict a zero response level even when one is known to exist.
The best it can do is to predict a very low probability of observing a re-
sponse, even at a zero dosage. But zero or undetectable responses appart-
ently do occur, as attested by frequent references to good health of humans
UJ
II •
UJ w
^
^~ 1—
>s
— 2
<Ł
-Jo
rt** i_io_
Q- —
U.
O
*
i | i j i j I
oAMPLE INITIAL MORTALITY
%j rn 1 Ti r L. u, 1 i H 1 I I *H U. r* n *.* T~M r~ n*r~AMr*
RESPONSE SAMPLE MEANS
A/
' SAMPLE
-r,10rroU^, r. „ MORTALITY
THRESHOLD J > /INDIVIDUALS
DOSE ' \ f\ /
\\ 1 1 / lĄ I
^ / I / if |
II
| / 1 / l\ 1
I » MM N-ERADICATION
/ \/ \ I
1 / X/ »A
• \' Ti 1 i
O.I
10
1,000 100,000
ABSORBED DOSAGE,
MG/KG BODY WEIGHT
Figure 2. Normal distribution of sample responses to incremental levels of
exposure to toxic substances, and distribution of estimated
sample means based on the sample.
and animals exposed to low levels of an imposing array of natural and syn-
thetic toxic materials.
Experience has shown that biological systems are remarkably well buf-
fered against toxic agents. Many natural foods contain toxins that are
-------
tolerated daily at low dosages, but without observable adverse effects; in-
deed, some natural materials that are toxic at high dosages are required for
adequate nutrition at some lower dose. Examples include copper, various
vitamines, sodium chloride and many others. The synthetic toxicants similar-
ly appear to have "no-effect" levels, even though the assumption of a normal
distribution of responses would preclude this conclusion.
The normal distribution similarly fails to predict threshold responses
of numbers of species within mixed species communities. Forest species may
be classified into several broad groups for convenient discussion of gen-
eralized community responses. Higher plants, fungi, fish, birds and mammals,
and insects differ substantially in their absolute sensitivity to pesti-
cides and in their exposure to aerially applied sprays. In general, plants
and insects receive a heavy exposure in relation to total metabolic tissue
because of high surface-to-volume ratios, surface orientation or both. Con-
versely, mammals have low surface-to-volume ratios and absorb poorly through
skin, while fish having similar surface area are further exposed through gill
action. Absorptive surfaces of fungi are usually protected from direct ex-
posure. There is therefore a generalized physical selectivity among organ-
isms based on variable likelihood of exposure to, and uptake of, a given
absolute dose. Superimposed on this exposure variable is a wide range in
sensitivity. If the absolute toxicity of a pesticide, eg. PGBE ester of
2,4-D, were considered in relation to these groups of organisms, it is
likely that responses would appear as in Figure 3a. The observed responses
to variable rates of application, however, suggest that specific toxicity
is a poor estimator of hazard in broadcast applications (Figure 3b).
59
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0
LU
*:
LU
UJ
o
cc
LJ
o.
100
50
O.I I 10 100 1,000
ABSORBED DOSE, MG/KG ORGANISM WT.
100
Q
LU
LU
CD
LU
O
cr
LU
Q.
50
T~
B
RATES«
FOR ,
1 WEED '
CONTROL
I
O.I I 10 100 1,000
APPLICATION RATE, KG/HA
Figure3. Responses of several groups of forest organisms to 2,4-D PGBE
ester in toxicity tests and in projected field applications,
without stream protection.
*NOTE: Insufficient data are available to illustrate responses of insects.
Fish data assume 100:1 concentration factor from water concentrations in
LC5Q studies, and 0.01 mg/1 in streamwater per kilogram-hectare application
rate. Mammal data assume consumption of five percent of body weight in
forage. Field data from birds inadequate for generalized response. Dotted
line assumes seed and insect foods contain 50 percent of that found in her-
baceous forage, 20 percent of body weight consumed per day. Mammalian
responses in field assume contamination of forage of 5 mg/kg for each
kilogram-hectare application rate and consumption of five percent of body
weight per day.
60
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Adequate data are not available to plot responses of forest fungi. The
fungi are important in water quality as the result of their roles in reten-
tion of nutrients and other solutes. In several reviews of impacts of ag-
ricultural pesticides on soil microflora, adverse effects were not reported
at field use rates (Audus, 1970; Bollen, 1961, 1962).
The expense of conducting "zero-response" tests on many species would
preclude precise identification of zero asymptotes even if such were possi-
ble. Safety factors are used to allow for variation in both sensitivity
among individuals and in the rate of exposure. Extra allowances are made
for safety as insurance against spills and species of unknown sensitivity.
The knowledge that species vary in response to toxins leads to the assump-
tion that there is always a more sensitive test species on which effects
haven't been evaluated, perhaps man. But groups of species tend to run in
patterns. Barring allergenic reactions, classical screening will identify
the groups illustrating extreme sensitivity. When these groups or members
thereof are identified as pests, the chemical is registered as a pesticide
for their control. Typically, registered herbicides are poor insecticides,
fungicides or rodenticides; insecticides are ineffective on plants but may
be highly toxic to other animal life. Traditionally, it has been uneconomi-
cal to use chemicals for controlling species other than the most sensitive.
The pesticides registered for use in forestry mostly have undergone exten-
sive use and testing in agricultural crops. The likelihood of major unex-
pected sensitivity appears remote.
Statistical problems are nearly insurmountable when extrapolating toxi-
city data from limited test populations to a virtually unlimited human pop-
ulation. Scientists traditionally ignore probabilities of 1:1,000,000 in
61
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test animals; they are untestable for practical purposes. Yet the expecta-
tion of harm to one human in a million is unacceptable. Mantel and asso-
ciates (1975) have developed probit-based testing procedures leading to
extrapolation for populations. These procedures have been used and stand-
ardized for chronic carcinogenic and teratogenic compounds, largely pharma-
ceuticals. They have not been associated with toxicity data regarding sil-
vicultural chemicals, and are probably inappropriate for most acute toxicants
because of their dependence on continuous normal distributions of responses.
For the present, the assumption must be made that there is indeed a
"no effect" level of every toxic chemical that does not produce an allergenic
reaction. Support for this assumption is widespread (CAST, 1974) but there
are many who object. The assumption is accepted here because the objections
have been identified principally with respect to chemicals other than those
used in forestry, with emphasis on chronic toxicants, carcinogens and tera-
togens. It must remain an assumption, however, because of the conceptual
impossibility of extending the normal curve to zero response. The chemicals
other than chlorinated hydrocarbons registered for use in forestry are not
chronically toxic except as noted hereafter, nor are they carcinogenic or
teratogenic at field use exposure rates. Several of these chemicals have
produced terata and tumors at extreme exposure rates, and such occurrences
enter into the establishment of safety factors.
The no-effect level is not the same for all organisms. It is neces-
sary to understand which organisms are likely to be exposed and how they are
exposed in setting concentration standards, and to make value judgements as
to which organisms or groups of organisms may be treated with some risk.
62
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Fish, aquatic plants, benthic organisms and water users are considered
in this analysis to be the most vulnerable to toxic hazard. Unfortunately,
the same sets of test data are not available for each group of organisms
exposed to each chemical. It is therefore necessary to establish patterns
of activity within chemical and test animal groups. While extrapolating
from groups to individual species increases the uncertainty factor, a sys-
tematic examination of patterns of activity of the chemicals, and of the
place in the food chain of the most sensitive organisms, helps to develop a
perspective of the responses of individuals within groups. These will be
described later in the rationale for setting concentration criteria.
The Roles of Concentration and Exposure in Estimating Toxic Hazard
Concentration of a toxicant is only one index of potential harm to an
exposed organism. Toxic hazard is related to level of exposure, duration of
exposure, route of contact with the organism, and absolute toxicity and
chronicity of the compound. A single statement of concentration setting
upper limits on contamination is not adequate as a measure of harm preven-
tion.
Concentration of a toxicant directly affects aquatic organisms only in
relation to the amount absorbed and period of retention. The presence of a
chemical is of no direct consequence unless the chemical enters sensitive
metabolic systems. This can occur through skin absorption, ingestion or
respiration; ingested material can enter either as a water solution or as
contaminated food or particulates. The likelihood of a given chemical con-
centration in water or food producing a specific body burden depends on its
ability to penetrate, persistence, (duration of exposure) retention in the
63
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organism and partitioning of the toxicant "between water and food or suspen-
ded solids. Also important is the ability of the chemical to be absorbed
through skin and intestinal membranes. Chemicals with a strong affinity for
surfaces may adhere to outer surfaces of food sources for other organisms.
Virtually all literature reporting responses of fish to toxic chemicals
expresses concentrations in terms of lethal concentrations to 50 percent of
a population (LC ) in 24, 48 or 96 hours. Some experiments have been run
to determine weight gain or loss and other subacute effects, but very few
studies are conducted in streamlike environments. Aquarium tank studies do
not give an accurate indication of lethality in streams. The nature of
their bias tends to overestimate expected toxicity in wild systems
(Muirhead-Thomson, 1971), thereby providing some safety factor at the outset.
They also protect fish from predation and certain diseases, however, so that
there is some compensation of bias.
Aquarium studies lead to overestimates of toxic hazard in several im-
portant respects. The first is that they test the effects of a known con-
centration that is not diluted over a period of time as a stream would be;
the second is that a glass system does not have substantial adsorptive ca-
pacity to tie up solutes. A third problem is that streams tend to offer
some escape opportunities downstream for mobile organisms. Steady states of
elevated toxicant concentrations do not occur in forest streams as a result
of the use of siIvicultural chemicals. Forest watersheds are characteris-
tically treated with chemicals that are immobile in soil. Chemicals gener-
ally enter water as droplets that drift onto open water surfaces, generating
contamination pulses or "spikes" that begin to dissipate immediately
(Norris, 1967). The integral of concentration during 24 hours is less for a
64
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variable concentration with a given peak than for a steady state at the same
maximum concentration (Figure 4). Assuming that such an integral is a rea-
sonable index of exposure in water, the spike concentration pattern consti-
tutes a lesser hazard to aquatics than a steady state of comparable maximum.
The tightly adsorbed character of most of the pesticidal chemicals, together
with the presence of suspended soils and rough bottom surfaces, removes the
chemicals even more rapidly than would be expected because of downstream
movement alone (Morris and Montgomery, 1975). Retention of chemicals by ad-
sorption raises several questions, however. Adsorption retains the chemicals
so as to extend the potential exposure period, albeit at low levels. For
<0
LJ
O
o
8°
.TYPICAL OBSERVED
1 CONCENTRATION
PATTERN
STEADY
STATE
24
TIME, HOURS
Figure 4. Comparison between typical pattern of concentration of chemical
in water from aerial application compared to static concentra-
tion (such as in aquarium test) leading to same total exposure
during 2L, hr. period. Note that the maximum concentration is
higher in the field, but that the subsequent exposure is lower.
65
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chronically toxic materials, this phenomenon could increase toxic hazard.
Degradation occurs in the adsorbed state, and the possibility exists that
toxic metabolites could be released within the aquatic community. Although
this may occur, the small amounts of chemical retained and lower level of
total metabolite than parent compound reduces the expectation of toxic ha-
zard to considerably lower than that of the original contamination. Reten-
tion could conceivably lead to reaction with stream nitrate, leading to
formation of N-nitroso derivatives of oncogenic potential. This process is
concentration dependent, however, and the concentrations of both pesticides
and nitrate are extremely low for such to occur. Rapid dilution of chemi-
cals occurs as water moves downstream from forest operations, reducing peak
concentration and perhaps providing escape opportunity for larger fish that
would not be predicted from aquarium tests. It therefore appears reasonable
that the estimates of "no-effect" levels from aquarium tests would hold for
wild aquatic systems, but that the reverse would not necessarily be true.
The presence of synergists can modify pesticide behavior in relation to
a particular organism. Muirhead-Thomson (1971) observed that detergents and
herbicides can influence sensitivity of fish to insecticides. This can occur
either through a slight change in the health of the organism that increases
vulnerability to other toxins or disease, or it can change the organism's
health or habitat so that it is subject to other harmful influences. Estima-
tion of direct effects in the presence of such confounding factors decreases
feasibility of field studies to support extrapolation from aquarium tests.
The tank tests are therefore necessary, but require a judgement-based safety
factor for field use in the absence of validation.
66
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The final point in estimating toxic hazard is the identification of
chronic effects from long term exposure. "Chronicity" is defined as the
ratio of dosage necessary to produce some level of response when adminis-
tered to laboratory animals as one dose, as opposed to many daily doses,
typically over a 90-day period. The number identifying chronicity is a
measure of the importance of minimizing any long-term exposure to a com-
pound; the lower the chronicity index, the greater the assurance that harm
can be avoided by avoiding peaks in the demonstrably toxic range of concen-
tration. Hayes (1967) derived chronicity indices for an anticoagulant ro-
denticide (Warfarin), a chlorinated hydrocarbon (DDT) and several organo-
phosphates (dichlorous, parathion and guthion). He observed very high
chronicity values (20.8) for the warfarin, intermediate for DDT (5.6) and
low for the organophosphates (0.8-1.16). He defined as those with a chron-
icity <_2.0 to be acutely toxic.
Fortunately, nearly all pesticides registered for use in forestry are
of the acutely toxic group. Their rapid disappearance in aquatic systems
permits dependence on regulation of peak concentrations for insurance of
fish safety. Endosulfan and lindane, seldom used near water, are the only
persistent and potentially chronically toxic compounds in use; reports re-
garding their theoretical chronicity were not found in this review. They
have not been reported as major water contaminants after forest insect con-
trol operations.
Application Factors Used in Setting Water Quality Targets
A "safety factor" is a ratio used to extrapolate from the lowest ob-
served toxic doses to estimated "safe" levels. It is not necessary or
67
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economically attractive to use chemicals at rates that cause serious prob-
lems in the usual course of operations; there is no justification for con-
taminating at lethal levels. However, it is necessary to use some chemicals,
and some quantity may inevitably reach some body of water. Below a certain
level of use, the consequences of reduced usage inevitably lead to an in-
crease in some other adverse consequences, such as lowered forest product-
ivity or an increase in use of a more damaging practice. Thus, in the
attempt to minimize total harm to ecosystems, it is necessary to allow the
temporary existence of low levels of contamination, with tolerable levels
established at some percentage of those estimated to cause "negligible" ef-
fects. Concentrations producing negligible effects cannot be determined
readily in the field, and "application" factors are used in estimating them
from laboratory data regarding lethal dosage. These are needed to compen-
sate for the admittedly imprecise lab data in setting water quality criteria
that provide safety over a range of conditions and species.
Forest watersheds have some features in common that influence the ex-
pectation of major harm from delivery of a toxic chemical into a stream.
Application factors can vary in different situations without compromising
safety. If a forest stream is small, it is likely that it will sustain ele-
vated concentrations for a matter of hours, and will join a larger stream
shortly. If fish are present, the population may be exposed without injury
to concentrations of chemicals that would cause injury over a prolonged ex-
posure period. The short term of exposure and escape opportunity offer more
safety than an aquarium test, and application factors can be relatively
small. If the stream is of large size, a given input of chemical will be
substantially diluted at the time of infall, and the expectation of local
68
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harm will be less than for the smaller stream although the ability to re-
cover may differ up or downstream. Contamination of the larger stream at a
harmful concentration poses a much greater chance of causing harm downstream,
however, because of the greater duration of exposure. Therefore a larger
factor is needed when larger streams are involved. Even in an aquarium, a
factor of 5:1 from LC^n levels reduces mortality to low levels with some
acutely toxic materials (Muirhead-Thomson, 1971). Larger factors are needed
in progressively larger aquatic systems to provide increased insurance.
Nevertheless, feeder streams are extremely important habitat for certain or-
ganisms, and contamination of large numbers of feeder streams increases the
contamination of large streams. Because of the greater likelihood of mas-
sive applications, and of direct injury to aquatic organisms, insecticides
require larger factors than herbicides as a general principle.
The above has outlined some generalizations that can be summarized as
follows:
a) For acutely toxic materials, limiting peak concentrations in
streams on the basis of aquarium tests of 24 hours or more offers more mar-
gin of safety than is suggested by aquarium data.
b) For chronically toxic materials, large safety or application fac-
tors are needed to insure against long-term effects. The basis should be a
longer-term exposure test, in the absence of which a 10-fold increase in
application factor is a minimum.
c) For any toxic material, small forest streams cleanse more rapidly,
hence will tolerate a given peak level of contamination more readily with-
out major harm than will larger streams. There is therefore justification
in using smaller safety factors on small streams than on large ones, except
69
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where spawning streams are treated at critical seasons. At such times,
factors for the next larger order of stream should be used.
d) Lower maxima are appropriate for extended exposure than for short-
term peaks with the same application factors in use. Since large streams
cleanse more slowly than small streams, and more diverse communities are
exposed, the larger the stream, the larger the needed application factor
from aquarium tests.
Proposed Criteria for Water Concentrations in Forest Watersheds
Criteria are given in Table 3 as targets toward which management prac-
tices can be directed. Rationale for each proposed concentration have been
developed from a review of literature on a variety of test organisms. Each
chemical for which an allowable concentration has been set has been evalua-
ted either as a natural component of aquatic systems and human diet, (e.g.
arsenic) or as a synthetic toxicant administered to a variety of test ani-
mals including fish. Many were tested on aquatic insects and crustaceans.
All proposed target maxima in feeder streams are substantially below
the concentrations causing significant mortality in the most sensitive known
test organisms. When the most sensitive test organisms were either resilient
species of insects or of crustacean species seldom inhabiting headwaters of
the forest streams, and data reflected 48-hour or more exposures to acutely
toxic chemicals, application factors of 20:1 below LC concentrations were
used because of the pulse nature of contamination. Greater application
factors were used where fish were the most sensitive group of organisms
(100:l), and for chemicals of suspected chronicity or known to accumulate
70
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in biological systems (200:1) unless otherwise noted. These factors are
increased for larger streams.
Concentration limits reflect the use to which water will be put.
Among the group of chemicals under consideration, e.g., some nitrates, are
of principal concern to the health of humans. Some are of concern because
of their immediate effect on fish; some of the insecticides are in this
class, especially chlorinated hydrocarbons. The herbicides, in particular,
are of concern more in potential irrigation water quality than in relation
to effects on fauna. Where water is not used for irrigation, criteria may
be based largely on hazard to aquatic species and humans.
The final point in qualifying target concentrations was stream magni-
tude. Small streams, i.e., those with flow rates less than 10 cubic feet
per second (ofs) elute quickly and are rapidly self cleansed after a pulse-
type contamination. There is no opportunity for sustained exposure, and
organisms not acutely influenced by the short term peak of chemical concen-
tration can be expected to recover rapidly and normally after exposure to
the chemicals listed. Larger streams and rivers, even of fast-moving water,
elute more slowly because of integrating much larger potential treatment
areas. Other important reasons for decreasing the concentrations allowable
in intermediate and larger streams are:
l) Concentrations change slowly in large or slow-moving streams, and a
greater chance for chronic exposure occurs from a given concentration.
2) Large streams at elevated concentrations elute larger amounts of
chemical into the next larger stream than feeder streams of the same con-
centration, thus creating more general pollution problems for a given level
of contamination.
71
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3) Large streams contaminated at high levels offer little escape op-
portunity for organisms.
4) Sustained high levels of contamination, as might be associated with
pollution of larger rivers, offer maximum opportunity for biomagnification
of compounds having this tendency.
5) Large streams have a high probability of being used for domestic
or irrigation use close to the point of contamination.
Accordingly, the following rationale are offered in support of concen-
trations suggested as targets in streams of the various magnitudes. Speci-
fic references and data citations are summarized in Appendix Table 1.
NITRATE
Nitrate is a highly soluble oxidation product of nitrogen that may be
an end product of any nitrogen fertilizer. Its natural occurrence in soil
and water is ubiquitous. The criterion of 10 mg/1 (as nitrogen) for all
streams is the same as recommended by the QCW. The rationale is that the
principal recipient of harmful effects from a short term elevated level
could be human infants. No distinction is made between stream size or dur-
ation of exposure, because nitrate is a chemical found naturally, and peak
concentrations can be superimposed on high natural levels so as to cause
difficulties. The same guide is used for irrigation water because of its
effect on ground water. Because of the pulse nature of potential contamina-
tion, potential effects on eutrophication are not considered here.
The point at which nitrate should be monitored should be at the source
of potable water, or at the irrigation pump.
72
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PHOSPHATE
Phosphate is an oxidation product of phosphorus, and is the form found
in rock phosphate fertilizer. Phosphoric acid is also used because of
greater solubility. Due to the wide range in phosphate concentrations re-
ported from natural forest waters, no criterion is suggested here. This
principle is in agreement with that followed by the Quality Criteria for
Water.
Data currently available from the Atlantic and Gulf coastal plain area,
do not indicate significant water quality effects from phosphate fertiliza-
tion at present. However, preliminary results (Avers and Scott, 1976) sug-
gest that if large portions (greater than 25$) of watersheds with very shal-
low water tables receive heavy applications of phosphate, slightly increased
phosphate concentrations in drainage water can be expected. The effect of
these levels on potential eutrophication is dependent on several factors
including temperature and turnover rate of impounded water. Economics of the
timber industry in the Southern U.S. indicates that management will become
more intensive and acreage under intensive management will continue to in-
crease. Periodic investigation of water quality effects from forest fer-
tilization in this area are thus advised, and future guidelines on water
concentration may prove feasible. These criteria should be established to
reflect the properties of the watershed in the maximum permissible levels.
AMTTROLE (3-amino-l,2,4-triazole; amino triazole)
Amitrole is a water-soluble compound used in the Pacific Northwest for
control of salmonberry in reforestation. Concentrations of this herbicide
are not considered in the QCW. Amitrole is a low-toxicity compound, with
-------
acute oral LD^0 in rats of 1100 mg/kg, and LC (48 hrs.) for coho salmon
of 325 mg/1. The two principal reasons for establishing a large safety
factor are that amitrole has been identified as a weak carcinogen (Jukes and
Schaffer, I960), and its application in irrigation water could conceivably
cause crop injury. Because of amitrole's status as a carcinogen, an extremely
large safety factor is needed to insure minimal risk.
The data for estimation of carcinogenicity of amitrole is not available,
and it is not possible here to estimate dose-response slope. Mantel's pro-
cedure (Mantel et_ al_., 1975) is useful in identifying the need for large
safety factors when dealing with any carcinogens. Amitrole's status as a
carcinogen is open to doubt because of reportedly reversible effects at 500
ppm in rat feed for 17 weeks (Jukes and Sehaffer, I960). Because concen-
trations are removed rapidly from water by stream bottom complexing and other
causes, (Marston et_ aJU, 1966; Norris et^ al_., 1966) the concern with extended
persistence at elevated concentrations is moderated. Under the circumstances,
application factors for potable water are based on Daphnia response, at 200:1
for extended exposure periods and larger streams, 100:1 for those streams of
medium size and 20:1 for small feeder streams. This provides for maxima of
.015 - .15 mg/1 in potable water. For irrigation water, an upper limit
of 0.1 mg/1 is proposed to minimize potential damage to crops. The pot-
able water criteria are established on the basis of known responses by
crustaceans, rather than mammals which are generally substantially less af-
fected by amitrole. Mammalian safety should therefore be well protected by
the given application factors, with margins of greater than 500:1 for short
term exposure (Jukes and Sehaffer, I960) and 5,000:1 in the longer term.
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AMMONIUM ETHYL CARBAMOYL PHOSPHONATE (Krenite)
This herbicide is used to control several deciduous brush species dur-
ing reforestation. The water-soluble material has unique properties rela-
tive to both brush killing mode of action and activity in water. The mater-
ial is a growth regulator related to both the carbamates and phosphates
while exhibiting the properties of neither. Mode of action is apparently
specific to inhibition of elongating cell walls, although there is limited
data on this subject. Among the few organisms tested, toxicity is neglibi-
ble to all fauna. Because there is little published data, Dr. James Harrod,
Biologist, DuPont Co., Wilmington, Del., was consulted for unpublished find-
ings. He indicated that Krenite has been applied to boll weevils, aphids,
roaches with no effect at any dosage including 0.5$ active drenching sprays.
At the highest dosage, carpet beetles and flies demonstrated some injury but
low mortality.
Bioaccumulation has not been observed in aquarium tests; residues in
fish were comparable to concentration in water. Teratological tests were
negative; carcinogenesis tests have not been done. Soil residue is short,
with half of the herbicide converting to carbamoyl phosphonic acid in two
weeks, which is oxidized to C0? and humic acid fractions within 8 weeks.
The highly soluble material adsorbs rapidly onto soil particles, and is not
taken up by roots or fungi. Disappearance from bottom sediments occurs
over a period of three months or less.
Ammonium ethyl carbamoyl phosphonate is evidently a very low hazard
herbicide. The rationale for setting maximum levels in rivers of 0.5 mg/1 is
that the 1,000:1 application factor, based on bluegills, allows use for all
75
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riparian brush control, and still provides for a large margin of safety in
consideration of the largely unknown properties of toxicology. Smaller
streams permit higher levels, as shown in Table 3, on the basis that more
is known about acute toxicity, and a wide safety margin is perceived even
when allowing concentrations consistent with aerial application to open
water.
ARSENICALS( organic)
Cacodylic acid and MSMA. are naturally occurring pentavalent intermed-
iates in the natural global arsenic cycle. They are used largely for tree
injection for control of unwanted trees, and also for control of bark beetles,
They are not considered in the QCW, which addresses arsenic as an elemental
pollutant. Because the pentavalent arsenicals are metabolized to form low
level equilibrium concentrations of trivalent compounds of greater toxicity,
it is appropriate to consider toxicological data from the trivalent mater-
ials in relation to prolonged exposures. It is also germane that a natural
background of elemental arsenic is ever present, and forest ecosystems have
equilibrated harmoniously in the presence of natural concentrations of ar-
senic as ASpOc ranging up to 6 ppm in soil (Greaves, 197<4; Norris, 197/4) and
that benthic organisms maintain populations at bottom mud concentrations of
1,920 ug/g arsenic (Leuschow, 1964).
The levels of arsenic concentration suggested by the QCW were based
entirely on inorganic trivalent arsenic, and were set at 0.05 mg/1 for pota-
ble water and 0.10 mg/1 for irrigation water. It is recommended that these
be accepted for a silvicultural target, with the exception that an increase
to 0.10 mg/1 is recommended for smsiller feeder streams as well, provided
76
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3. Recommended concentration maxima for silvicultural chemicals by stream class and user
group. Potable waters include safety factors for wildlife and aquatic organisms as
well as humans.
Criteria, PPM 24 hr. Mean
Stream Class & User
Class Chemical
Fertilizer Nitrate
Phosphate
Herbicide Amitrole
Ammonium ethyl
carbamoyl
phosphonate
Arsenicals
(organic)
Dalapon
Dicamba
Dinoseb
Picloram
Silvex1
Triazines
2,4-D1
2,4,5-T1
Most Sensitive Test Test Basis &
Species Affected Concentration
Man
Algae
Daphnia
Bluegill
Man
Daphnia
Bluegill
Bass
Chinook salmon
Daphnia
Bluegill
Bluegill
No effect, 10 mgA N
Growth response var.
LC5Q 48 hr, 3 mg/1
LC50 48 hr,
No effect,
LC5Q 48 hr,
LC5Q 96 hr,
LC5Q 48 hr,
LC5Q 48 hr,
LC5Q 48 hr,
LC5Q 48 hr,
LC 48 hr,
670 mg/1
0.12 mg/1
11.0 mg/1
<_ 10 cf s
Potable Irrig .
10* 10*
.15 0.1
5 5
.1 .1*
.5 .1
23. mg/1 .2 .004
19.7 mg/1 .5 .001
1.2 mg/1 .06 .02
1.0 mg/1
1.0 mg/1
1.4 mg/1
.05 .05
.05 .05
.06 .02
10 cfs-Navigable Navigable
Potable Irrig. Potable Irrig.
10*
.te basis
.03
1
.05*
.1
.05
.05
.03
.03
.05
.03
10* 10*
for recommendatioi
.01 .015
1
.1*
.02
.002
.0005
.02
.03
.02
.02
0.5
.05*
.10
.01
.005
.01*
.01
.01
.01
10*
.01
0.5
.1*
.02
.001
.0001
.01*
.01
.005
.01
-------
Table 3. (continued)
Criteria, PPm 24 hr. Mean
Stream Class & User
(X).
Class Chemical
Herbicide TCDD
Insecticide Carbaryl
Diazinon
Disulfoton
Endosulfan
Endrin
Fenitrothion
Guthion
Lindane
Malathion
Phosphamidon
Trichlorfon
Most Sensitive Test Test Basis &
Species Affected Concentration
Coho salmon
Stonefly
Daphnia
Stonefly
Rainbow trout
Coho salmon
Atlantic salmon
Stonefly
Brown trout
Daphnia
Daphnia
Stonefly
No effect 96 hr,
.000000056 mg/1
^50
LC50
^50
^50
^50
48
49
48
96
96
hr,
hr,
hr,
hr,
hr,
.0048 mg/1
.0009 mg/l
.005 mg/1
.0003 mg/1
.0005 mg/1
Behavior test 1 mg/1
LC50
M50
^50
^50
K,n
96
48
96
48
96
hr,
hr,
hr,
hr,
hr,
.0015 mg/1
.002 rag A
.0018 mg/1
.0088 mg/1
.016 mg/1
<_ 10 cfs
Potable Irrig .
.001
.0001
.001
.00003
.00005
.025
.0003
.0001
.0005
.0005
.002
QQ
.001
.0001
.001
.00003
.00005
.025
.0003
.0001
.0005
.0005
.002
10 cfs -Navigable
Potable Irrig.
0000006 for all wa
.0005
.00005
.00025
.00001
.00001*
.01
.0002
.00005
.0002*
.0005
.0005
.0005
.00005
.00025
.00001
.00001*
.01
.0002
.00005
.0002*
.0005
.0005
Navigable
Potable Irrig .
.0002
.00001
.00024
.000003
.000005
.005
.00007
.00001*
.0001
.0002
.00005
.0002
.00001
.00025
.000003
.000005
.005
.00007
.00001*
.0001
.0002
.00005
* As listed in QCW.
The phenoxy herbicides may occur in water as esters or other forms. The given criteria for potable water may be increased by
a factor of 10 for forms other than esters. Criteria for irrigation use are for total phenoxy herbicide.
-------
the source is a pentavalent compound. Where natural levels exceed these
amounts, recommended maxima are 10 percent increases over background levels
for a period not to exceed one year.
DALAPON (2,2-dichloropropionic acid)
Dalapon is a moderately specific grass herbicide used in reforestation
weed control. It is water soluble but not notably mobile. Daphnia are the
most sensitive group of aquatic test organisms showing a response to dala-
pon (48-hr. LC^ 11.0 mg/l). This herbicide is of low general toxicity to
mammals, with acute oral LD on rats estimated at 3860 rag/kg, and LC_n 48-
hour exposures to fathead minnow, bluegills and coho salmon ranging from
290 mg/l to 340 mg/l. Because of the relative sensitivity of Daphnia, the
application factor is based on potential damage to aquatic food insects
rather than toxicity to potable water users. For maintenance of stream
bottom populations, an application factor of 100:1 is used in all but the
smallest streams, in which a factor of 20:1 is used in relation to a short
term maximum. A margin of safety above that needed for aquatic fauna is re-
quired for irrigation water, because dalapon is more harmful to plants, es-
pecially grasses, than to animals. This margin may be estimated from re-
cords of plant injury and data on plant control.
Dalapon is used as a selective herbicide in crops at rates usually in
the vicinity of 51 Ibs/acre (55 kg/ha) as the 85 percent active product;
in sugar cane, one registered use extends down to 1 Ib/acre (l.l kg/ha)
which it is stipulated by the label that only small sensitive weed grasses
are affected. A no-effect level to plants cannot be calculated precisely
from these data, but it is estimated that a level amounting to one percent
79
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of the median of registered use rates, i.e., 0.05 Ibs/acre (44 kg/ha), would
have a level of activity well below the amounts causing depression of yield.
An acre foot of water carrying 0.018 mg/1 of dalapon would apply 0.05 pounds
per acre (0.055 kg/ha). Dalapon has a biological life expectancy in soil
of three weeks, or less, which is shorter than the period over which 12" of
irrigation water would normally be applied. Accordingly, the application
factor of 100:1 for crop tolerance leads to an allowable level of 0.02 mg/1
in sources of irrigation water. Because of the brief nature of concentra-
tions in small streams, higher maxima would not lead to a harmful accumula-
tion on the crop, and a maximum of 0.1 mg/1 is recommended.
DICAMBA(3,6-dichloro-o-anisic acid; Banvel)
This chemical is a herbicide of the benzoic acid family. It is of the
growth regulator group, and is effective as a brushkiller in some circum-
stances in which phenoxy herbicides are inadequate. Formulated as amine
salts, it is water soluble and somewhat mobile in soil. Dicamba has consid-
erable soil activity, and the compound is relatively persistent. Soil
activity can persist for six months at the rate of one pound active per acre
(Newton, M., Oregon State University, unpublished observations).
Dicamba is of low acute toxicity to mammals, with acute oral LD val-
50
ues of over 1000 mg/kg f°r several species. Effects on fish have not been
widely investigated, but the bluegill demonstrates LC levels of 23 mg/1
for 96 hours. Crayfish all tolerate much higher considerations.
Dicamba is used only infrequently for general forestry site preparation.
For this reason, it is unlikely to appear in large amounts or in a chronic
80
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pattern necessitating a large application factor. Based on bluegills, a 100:1
factor can be used for small streams, permitting a 24-hour mean maximum of 0.2
mg/1. Much less of this persistent growth regulator is tolerable for irrigation.
DINOSEB (4,6-dinitro-o-sec-butylphenol, DNBP, Dinitro)
This compound is a herbicide of the substituted phenol class. It is a
desiccant having the effect of contact action on all green vegetation. Its
only registered use in forestry is in accordance with state labels permitting
its use prior to burning for forest site preparation.
Dinoseb is the most toxic of the herbicides used in forestry. Acute
toxicity to mammals is in the very toxic range, of 20-25 mg/kg in mice, rats
and guinea pigs and 4-0 mg/kg for chickens. No data were found in the liter-
ature on fish and aquatic insects, but LC values for 96 hours on scud in-
dicated much lower toxicity to this life form than would be anticipated for
an insecticide of comparable toxicity to mammals.
Dinoseb has only recently been registered for use in forestry (Oregon
State Label). Despite its long history as an agricultural chemical, data
pertaining to aquatic organisms has been difficult to obtain. For the pre-
sent, the data base is too fragmentary to recommend a specific water toler-
ance.
PICLORAM(4-amino-3,5,6-trichloropicoliiiicacid; Tordon)
Picloram is a herbicide of the pyridine family used for controlling
brush prior to tree planting. Like dalapon, picloram is a low-toxicity
brushkiller in relation to mammals and stream fauna. The most sensitive
species reported, largemouth bass, shows an LCc for 4-8 hours of 19.7 mg/1;
81
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rats, guinea pigs and birds all demonstrate acute oral LDcn levels of 3,000
to 10,000 ing/kg. It is relatively persistent and mobile, and a larger-
than-average application factor for mammals of 500:1 is proposed. Thus,
pin
the criteria for potable water would permit ingestion of .-jr. g = .42
grams in two liters water, or 210 mg/1. This concentration is known to be
severely phytotoxic to trees and broadleaf plants, however, and the allowa-
ble concentration suggested reflects a concern for irrigation water rather
than a problem with acute toxicity to animals. Quality criteria will there-
fore be based entirely on likelihood of injuring aquatic and crop plants.
Picloram is among the most active of the herbicides. Dosages of one-
half gallon per acre (4.7 1/ha) of Tordon 101 herbicide (containing .263
kg/ha picloram) are recommended as a minimum for certain weed problems. One
pound picloram per acre (1.15 kg/ha) is approximately the median dose, and
it is usually mixed with four pounds 2,4-D. Applying an application factor
of 100:1, or 0.01 pounds per acre (0.011 kg/ha), would permit a concentration
of 0.004 mg/1 for one foot of irrigation water. Bruns e_t al_. (1972) ob-
served that 0.040 mg/1 in irrigation water caused slight injury to cotton in
three subsequent irrigations, but did not cause a reduction in yield. Le-
gumes, tobacco and potatoes are more sensitive than cotton. The latter,
especially, are extremely sensitive. Dr. Alex Ogg, U.S.D.A., Prosser, Wash-
ington, (personal communication, 1976) has observed damage typified by mal-
formed stalks and stunting, as well as malformed growth from tubers thus
treated, when potatoes were irrigated for an extended period with water
containing picloram at .0005 mg/1. It appears that for picloram and other
growth regulating herbicides, an application factor of 100:1 below median
dosage is inadequate. The adoption of .0001 mg/1 as a criterion for
82
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irrigation water over long periods poses analytical difficulties in monitor-
ing. It is necessary, however, to insure some measure of safety for any
irrigator. The level of .0001 mg/1 is tentatively proposed for irrigation
water over extended periods. Concentration maxima of .001 mg/1 proposed for
short term peaks in feeder streams would be unlikely to provide a quantity
of contaminated irrigation water that would be likely to cause injury, al-
though some malformation could occur without loss of yield. Potato bioassay
may be the most sensitive analytical technique for monitoring.
SILVEX( 2-(2,4,5-trichlorophenoxy)propionic acid)
Silvex is a phenoxy herbicide used for several specific brush control
jobs in forest site preparation and release. Like the other phenoxys, it is
neither persistent nor mobile. This material has been registered for many
years as an aquatic herbicide. Its effects have been tested on a wide range
of aquatic and warm blooded species. Silvex is of medium to low toxicity
among mammals and birds, with acute oral LD5r) values in the range of 600 to
2,000 mg/kg. The range of concentrations at which fish have demonstrated
LC,-~ concentrations for 48 hours extends from 1.23 mg/1 for the chinook sal-
mon to 83 mg/1 for bluegills. Formulation is important, with esters tending
to be more toxic to fish than salts. Because esters are more widely used in
forestry than are other formulations, and fish appear to be among the more
sensitive organisms, the safety factor is based on salmon responses to es-
ters, rather than on the expectation of mammals being affected by drinking
water. Of the esters, those containing butyl groups in the alcohol chains
appear to be most toxic to fish. These include the butyl, butoxy ethanol,
propylene glycol butyl ether esters and perhaps others.
-------
A long-term application factor of 100:1 is proposed to allow for the
most sensitive fish being exposed to a butyl-containing ester; i.e., 0.01
mg/1 is proposed for the maximum concentration in large streams; this cor-
responds to the levels recommended by the QCW, and is one-third of that sug-
gested by Rohlich (1972) for potable water. Higher maxima are recommended
for smaller streams on the principal that exposures are of very short term.
Moreover, the extensive experience with silvex as an aquatic herbicide has
not led to obvious problems, suggesting that short term exposure to one-
hundredth the registered aquatic weed control dosage will not lead to long
term injury.
Silvex in irrigation water has been studied by Bruns et_ al_. (1973), who
reported that concentrations in the range suggested for potable water do not
cause yield reductions for sugarbeets, soybeans, or corn. Soybeans, the
most sensitive crop studied, were adversely affected at 0.02 mg/1 in irriga-
tion water, in which the principal effect was a slight reduction of seed
quality, without reduction in yield. No effects were observed below this
level. Growth regulator activity is apparently present to a lesser degree
than in 2,4-D and picloram.
Silvex is one of the several products made from intermediates contain-
ing TCDD. This compound will be considered separately in relation to its
own toxicity and criteria. Its concentration in silvex is regulated by
mutual consent among manufacturers at 0.1 mg/kg of silvex acid, at which
concentration its contribution to toxic hazard is well below that of silvex,
despite its extreme absolute toxicity. It will therefore not be considered
in the determination of silvex criteria.
-------
S-TRIAZ1NES (atrazine; simazine)
Atrazine and simazine are low-solubility, low mobility herbicides whose
biological effects are generally expressed in the inhibition of photosyn-
thesis. They are widely used for herbaceous weed control in plantations.
They are of generally low toxicity to warm blooded animals and fish, with
warm blooded animal acute oral LD50's in the range of 1,750 mg/kg for atra-
zine fed to rats and mice, to 5,000 mg/kg, also for rats, exposed to sima-
zine. Long-term cattle-feeding studies with 750 mg/kg/day of simazine caused
weight loss with no mortality. Simazine is registered as an aquatic herbi-
cide.
Fish are quite tolerant of the triazines. Tests with various game-fish
have placed 48-hour LC 's in the range of 4.5 mg/1 for rainbow trout to
118 mg/1 for bluegills. Daphnia, however, were affected by lower concentra-
tions of simazine, with 1 mg/1 for 48 hours an estimated LC5f) (Sanders,
1970). In terms of potential harm to fauna, then, it is most probable that
the triazines will exert their effects primarily at the lower trophic levels.
Because of the resiliency of this group of organisms and the general toler-
ance of most of the vertebrates, the application factor of 100:1 could be
based on the Daphnia, allowing large river concentrations of 0.01 mg/1.
Much higher concentrations (5.0 mg/1) are used in aquatic weed control, and
the above criteria should not be construed as limiting use of the triazines
for that purpose.
The generally specific nature of triazines as herbicides suggests that
they may require more stringent limitations in irrigation water than in
water used for other purposes. The triazines are not considered growth reg-
ulator herbicides, and a safety factor can logically be derived from
85
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recommended use rates. Simazine and atrazine are generally recommended for
use between 2 and 4 Ibs/acre (2.2 to 4-4 kg/ha), with a median dosage of
about 2 1/2 pounds, active, (3 kg/ha). Using the same factors and calcula-
tions as for dalapon, a safe concentration level is calculated at 0.01 mg/1,
the same as for potable use, and equal to the level recommended for aquatic
systems by Rohlich (1972).
Triazines are more persistent than dalapon, and the use of calculations
based on the shorter residual compound should be examined in terms of avail-
able data on crop sensitivity. Ries et_ al_. (1967) studied the responses of
several crop species to triazines at application rates in the range of grams
per acre. He observed that crop yields were not substantially affected by
these low rates, but that the protein contents were increased. His studies
were conducted on several species of grains as well as on peas, all of which
appeared to tolerate the proposed concentration without harm. The calcu-
lated long-term maximum of 0.01 mg/1 is therefore recommended for irrigation
water. The higher levels proposed for smaller streams reflect the likeli-
hood of transience of contamination. The upper limit of 0.05 mg/1 in
feeder streams is substantially below the LC5Q for the most sensitive aqua-
tic species known, and provides an application factor of 10,000:1 or more
for potable water users.
2,4-D (2,4-dichlorophenoxyacetic acid)
This phenoxy herbicide is one of the most commonly used herbicides in
forest weed and brush control, aquatic weed control and in the growing of
grain crops, and has been extensively tested for toxicity on many organisms.
It is immobile in soil, and is degraded rapidly in plants and soil. It is
86
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in the medium toxicity range, with acute oral LD^- ' s for warm blooded
animals in the range of 368 mg/kg for mice to 2,000 mg/kg for mallards.
Toxicity to fish is moderate to low, depending on formulation. The acid
of 2,4-D is very low in toxicity, with LC6f) values ranging from 375 mg/1
for bass to 390 mg/1 for bluegill in 48-hour tests. Formulation as esters,
however, decreased the LC values for bluegills to a range of less than
1.0 to 9.0 mg/1, depending on which ester was used; the low volatile esters
most commonly used in forestry ranged from 3 KigA "to 9 nig/1. As with sil-
vex, esters containing the butyl group appear to be the most toxic. Stone-
flies, with LC5Q values for the butoxyethanol ester of 1.6 mg/1, were com-
parable in sensitivity to bluegills; crayfish were very low in sensitivity,
with 48-hour exposure to 100 mg/1 producing no visible effects. Meehan
et al. (1974) reported extreme sensitivity of Alaska salmon species to the
butyl ester, which is not registered for forestry use.
Fish are apparently the most sensitive group of animals in response to
direct exposure. This, plus the extensive use of 2,4-D, suggest the use of
a moderately large safety factor when using ester formulations. Based on
LC,-n value of 1 mg/1 and a 100:1 application factor a sustained river con-
centration of .01 mg/1 would be "safe" for fish and furnish a very large
margin of safety for potable use. For 2,4-D amine, .1 mg/1 would be per-
missible with a larger safety factor, and it is recommended that tolerance
levels of 2,4-D acid or amine be higher than for the esters by a factor of
ten except for irrigation uses. Because hydrolysis of the esters to acids
begins to occur immediately, it is recommended that the efforts to monitor
make the distinction between forms in each analysis. The stated criteria
for potable use apply only to the ester fraction.
87
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Irrigation water must consider the growth regulating properties of
2,4-D. Beans, potatoes, grapes and cotton are severely affected by very
low rates of 2,4-D. Unlike picloram, however, 2,4-D is rapidly destroyed
by metabolic activity in the plants, and it is not as damaging to sensitive
crops at extremely low concentrations as is picloram. Studies of 2,4-D in
irrigation water have been conducted with sensitive crops. Concentrations
of 0.22 mg/1 caused visible symptoms but no yield reductions in soybeans
and sugar beets. Concentrations of 0.022 mg/1 did not injure any crop
visibly. Crops did not carry detectable residues (Bruns et_ al_., 1973).
Because of the growth regulator properties of 2,4-D, concentrations in
irrigation water have to be maintained at lower levels than would be dic-
tated for drinking water or fish habitat. The proposed level of 0.005 mg/1
provides for a margin of safety of 5:1 below the apparent minimum limits of
crop sensitivity; the increased concentrations permitted in feeder streams
will apparently not exceed levels at which aquatic communities will be dam-
aged, and they are lower than the suggested maxima listed in the QCW, or
recommended by Rohlich (1972).
2,4,5-T (2,4,5-trichlorophenoxy acetic acid)
2,4,5-T is the phenoxy most widely applied by aircraft for brush con-
trol in the reforestation of forest lands. The toxic hazards associated
with 2,4,5-T have recently received intensive study. Because of its wide
use in forest management, it is among the most likely to find its way into
forest waters through direct application to water surfaces.
This compound is very closely related to silvex, both chemically and
toxicologically. It is non-persistent in soil (14-30-day half life) and low
-------
in mobility (Norris, 1970; Blackman et_ aiU, 1973). It is used at similar
rates of application, has a similar spectrum of biological activity and is
also applied in identical formulations.
Teratological studies have dominated the adverse findings regarding
2,4,5-T. Courtney et_ al. (1969) reported that 2,4,5-T caused birth defects
in mice receiving dosages of 46-113 mg/kg/day for 9-10 days during early
pregnancy. Their findings were tempered by the discovery that their 2,4,5-T
contained 27 parts per million TCDD (Leng, 1974), "but later reports have
confirmed that levels of 2,4,5-T high enough to cause distress to the dams
can cause some anomalies in the litters even with TCDD levels at 0.1 mg per
kg 2,4,5-T acid or less, the prevailing purity standard (Courtney et al.,
1970). Goldberg (1970) does not regard their data as evidence that low-TCDD
2,4,5-T is a teratogen. Because of the high levels used in these toxicity
tests, and the evidence of toxic effect at these dosages on the mothers, the
question has not been resolved as to whether 2,4,5-T is a teratogen, or
whether fetal distress was the result of maternal stress. In any event,
embryotoxic effects have not been demonstrated with single dosage or at
chronic dosages substantially below those producing direct toxicity symptoms.
The dosages at which harmful effects have been reported place 2,4,5-T
in the medium-toxicity class. Rowe and Hymas (1954) reported acute oral
LD levels for rats at 495-750 mg/kg, similar to silvex. Guinea pigs are
apparently more sensitive to 2,4,5-T than to silvex, with acute LD^ levels
of 380 mg/kg for 2,4,5-T as compared to 1,250 mg/kg for guinea pigs. Dogs
are reportedly among the most sensitive animals in acute oral dosage tests,
with LD _ levels in the vicinity of 100 mg/kg.
89
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Feeding studies have shown mammals to pass 2,4,5-T through their diges-
tive systems without substantial uptake or modification. Cattle and sheep
were fed at the rate of 100 mg/kg/day for cattle and 50 mg/kg/day for sheep
for ten days without observable effects. Chronic levels needed to cause
minor weight loss in dogs was 10 mg/kg/day. Because much of toxicity data
for 2,4,5-T were reported before the discovery of the counfounding from TCDD
and the reduction of the concentration of TCDD in production grades of her-
bicide, it is likely that the values reported provide some additional margin
of safety.
The effects of 2,4,5-T formulations on fish are very similar to those
of silvex. LC, ' s of 1.4 mg/1 are reported for the most toxic esters on
bluegills. Again, there appears to be a wide range of toxicity among the
esters, and amine formulations are substantially less toxic than any ester;
standards for the forms other than esters are suggested at ten times those
of the esters. For this reason, monitoring of 2,4,5-T should identify esters
distinct from other forms. Because the patterns of 2,4,5-T
effects on various species are similar to silvex, the same rationale is used
for recommending water quality criteria, and the same levels are proposed.
These range from .01 mg/1 in large streams to .06 mg/1 in feeder streams.
These concentrations are higher than those listed by Rohlich (1972) on the
basis that concentrations of TCDD in production grade 2,4,5-T are considerably
less than one tenth of those assumed to be present in his calculations.
Moreover, the question of TCDD is handled separately here, and either 2,4,5-T
or TCDD criteria may be used to determine the need for pollution control.
90
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TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin)
TCDD is an unavoidable contaminant in all pesticide products in which
2,4,5-triehlorophenol is used as a manufacturing intermediate. It is a
highly insoluble and immobile material that is persistent in soil but rapidly
degraded in vegetation (Crosby and Wong, 1976). This material is among
the most toxic synthetic substances known to man. The amounts which are
present in 2,4,5-T and silvex sold as commercial products is controlled by
the manufacturers to have concentrations of 0.1 mg of TCDD per kilogram of
phenoxy acid equivalent, or less. Unpublished data from the EPA Dioxin Im-
plementation Program indicated that current 2,4,5-T production samples were
in the vicinity of .01 mg TCDD per kg 2,4,5-T, or less.
TCDD apparently does not figure substantially in the acute oral mam-
malian toxicity of phenoxy herbicides meeting the 0.1 ppm TCDD concentration
standard. Rats, mice and rabbits demonstrate acute oral LD^Q'S of 0.022
mg/kg, 0.114 mg/kg and 0.115 mg/kg respectively. Guinea pigs are extremely
sensitive, with an acute oral LD_0 of 0.0006 mg/kg. The ratio of toxicity
of TCDD to 2,4,5-T is greater for guinea pigs than for other mammals studied.
at 1:750,000; for many species the ratio is about 1:100,000. Since the
ratio of occurrence of 2,4,5-T to TCDD is 10,000,000:1 or greater, there is
little likelihood of being able to observe TCDD effects when administered in
a phenoxy vehicle.
Fish are apparently the most sensitive organisms among those studied
for the effects of TCDD. Miller (1974) did, however, discover an apparent
level at which coho salmon in glass environments tolerated TCDD without
measurable effects on weight gain or other vital functions. This dosage was
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.000056 mg/kg, based on mg TCDD in an aquarium per kilogram live weight of
fish. Over a 60 day period, however, Miller et_ al. (1973) had observed
an LC5n for rainbow trout of 0.056 ug/1 in solution, and an absence of
chronic effects in fish diets. Miller's work was remarkable in demonstrat-
ing that a 4-day exposure at these low levels produced mortality that con-
tinued for 60 days. These data suggest that fish can accumulate amounts of
TCDD that produce symptoms after withdrawl but before they can be eliminated.
Isensee and Jones (1975) investigated the tendency for this chlorinated
hydrocarbon to be magnified by biological systems. Their data led to the
conclusion that organisms exposed to an environment containing a given con-
centration of TCDD would develop concentrations of TCDD substantially higher
than that of the water. Miller's findings (1974) indicate that fish in a
glass-enclosed system may function as a sink for TCDD, but consumers at
higher trophic levels were not found by Isensee to accumulate substantially
increased levels as the result of ingesting prey with elevated TCDD levels
in or on their bodies. The tendency for TCDD to accumulate in mammals is
similar to that of other chlorinated hydrocarbons. Rose et al. (1976) de-
monstrated that chronic feeding of rats with .00001 to .001 mg/kg/day led to
equilibrium concentrations in 13 weeks. After withdrawal, residues in the
rats declined with half lives of 23.7 days, regardless of dosage. This
strong evidence of accumulation is thus coupled with a tendency for elimina-
tion or detoxication systems to continue functioning despite prolonged ex-
posure. Following the study by Norris and Miller (1973) indicating lethality
to guppies of .0001 mg/1 in water, Norris1 has indicated in personal
Norris, L. A. U.S. Forest Service, Forestry Sciences Laboratory,
Corvallis, Oregon.
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communication that an estimated no-effect concentration of TCDD in water in-
habited by guppies or coho salmon is between 0.05 and 0.005 parts per tril-
lion, (.00000005-.000000005 mg/l).
The toxicity of TCDD in aquatic systems is very difficult to evaluate,
and safety estimates must remain at least partly conjectural. This sub-
stance is extremely insoluble in water, at 0.0002 mg/l solubility. It has
a very strong affinity for some surfaces (Miller, 1974). Stream-bottom
rocks, plants and organic debris probably bind TCDD so extensively that it
is difficult to maintain a solution of TCDD at a steady state for investiga-
tion. For the very same reason that such investigations are nearly impossi-
ble in other than clean aquarium systems, the material appears unlikely to
remain in stream water in detectable concentrations. The rationale in pro-
posing a maximum concentration of .006 part per trillion (.000000006 mg/l)
for all water is based on the existence of data suggesting that this level
is unlikely to cause effects, and the evidence that a concentration of this
order would be unlikely to persist more than briefly. It is also far below
the limit of detection. Quality control can, however, be achieved by ob-
serving contamination limits for 2,4,5-T and silvex containing 0.01 mg TCDD/
kg acid equivalent or lower levels accordingly for more contaminated herbi-
cide, provided the calculated amount is not exceeded.
CARBARYL (1-naphthyl N-methylcarbamate; Sevin)
This insecticide is of the carbamate group, and has found wide usage
for control of forest defoliators because of safety, short residue, and re-
strictions on use of chlorinated hydrocarbons. It is of medium mammalian
toxicity, with acute oral LD 's ranging from 280 mg/kg in the guinea pig to
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710 mg/kg in the rabbit. Carbaryl is lower in toxicity to fish than are
many of the insecticides used in forestry. Macek and McAllister (1970) re-
port 96-hour LC 's for eight species of fish ranging from 0.764 to 20.0
mg/1; coho salmon were the most sensitive while catfish were the most re-
sistant.
Arthropods are quite sensitive to carbaryl. Stonefly LC is 0.0048
mg/1 and crayfish only slightly less sensitive at 0.0086 mg/1. Dungeness
crabs are less sensitive, having an LC,-n for 96 hours of 0.180 mg/1. Other
estuarine organisms, including two species of oyster and bay mussel toler-
ate carbaryl at much higher concentrations, with LC-'s of 2.2 and 3.0 mg/1.
The sensitivity of species on which fish depend for food suggests that
criteria be directed toward the protection of this portion of the aquatic
system. Because carbaryl is a non-accumulating insecticide of short re-
sidual life, the criteria can be set so as to prevent a pulse concentration
from causing short term damage to food arthropods. An application factor
of 20:1 will prevent mortality of food insects. If the application factor
of 20:1 is to be used in large rivers, the resulting maximum concentration
of .0002 mg/1 would give a factor of 900:1 for Dungeness crab and more than
2,500:1 for other members of the aquatic ecosystem covered in this review.
Somewhat higher concentrations could be tolerated in feeder streams with
minimal effect on benthic organisms. Concentrations of carbaryl at these
levels would not influence irrigation water quality. These concentrations
are higher than those recommended by Rohlich (1972) on the basis that
chronic exposure is unlikely.
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DIAZINON (0,0-diethyl 0-(2-i8Opropyl-6-methyl-4-pyrimidinyl)pho8phorothioate)
This insecticide is of the organophosphate class. It is used very lit-
tle in forest crops, and does not have general registration for aerial ap-
plication. It is considered here because of its occasional use on ornamen-
tals, especially Christmas trees, near inhabited areas.
Diazinon is regarded as moderately toxic to laboratory animals via oral,
dermal and inhalation routes. Chronic effects were not observed in rats fed
diets containing 100 ppm for two years, nor in dogs fed 5.2 mg/kg/day for
43 weeks. Monkeys fed at rates of 5.0 mg/kg/day for 106 weeks showed cho-
linesterase inhibition but no other symptoms. Tolerances in food have been
set in most food and vegetables at 0.75 ppm (Von Rumker et_ a^., 1974). There
appears little likelihood that harm to humans will result from registered
usage.
Certain aquatic organisms and birds appear to be more sensitive to dia-
zinon than are mammals. Rainbow trout and bluegills apparently can tolerate
high levels, with LC^Q levels ranging from 30 to 170. mg/1 for 48 hours.
Stoneflies are slightly more sensitive, with LC^n values of 25 mg/1 for 96
hours. The oral acute LD^Q to birds, including the mallard, ranged from
2-4.3 mg/kg. Sanders and Cope also reported that Daphnia LC5n was 0.9 mg/1
for 48 hours.
Von Rumker et_ al_. (1974) observed that diazinon is moderately persis-
tent in the environment. Because of the tendency to stay in place, they
concluded that this material is unlikely to cause harmful effects in aquatic
systems away from the target area. The finding that the most sensitive
group of species, Daphnia, shows no effect from exposure to 0.26 mg/1 lends
credence to this general conclusion.
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Using an application factor of 100:1, (because of persistence) from
the concentration causing 50 percent mortality in the most sensitive spe-
cies with a two-day exposure, a large-river concentration of .00001 mg/1
would appear to provide a substantial margin of safety for fish and food
species. Because irrigation water containing diazinon is unlikely to cause
damage or illegal residues in crops, the same standard can be used for pot-
able and irrigation uses. This concentration is close to that suggested by
Rohlich (1972), but higher maxima are proposed for smaller streams with less
likelihood of chronic exposure.
DISULFOTON(0,0-diethyl-5-(2-(ethylthio)ethyl)phosphorodithioate)
This insecticide is of the organophosphate group, and is considered in
the very toxic to extremely toxic range. The material is registered only
for use on ornamentals, including some forest species, and has not been used
on a massive scale.
Disulfoton has been studied for its toxicity to rats, birds, fish and
aquatic insects, among other organisms. There is a large amount of varia-
tion in sensitivity among groups of animals. Acute oral LD5n for rats is
12.5 mg/kg. Bobwhite quail are far less sensitive, with LD-,-, at 800 mg/kg,
but fish can be quite sensitive. Pickering (1962) reported that fathead
minnows are very sensitive to disulfoton, with 96-hour LC_n levels at 0.063
mg/1. He observed, however, that bluegills were considerably more resis-
tant, with the LC50 level at 3.7 mg/1. Stoneflies are highly sensitive;
the LC.Q level for 48 hours is 0.005 mg/1 and the LC5Q for 30 days is ap-
parently about one third the level expected for 24 hours.
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Recommended criteria for disulfoton are based on the rationale that
this compound is neither persistent nor mobile, and its use pattern vir-
tually prevents the occurrence of any chronic exposure. The maximum con-
centration in large rivers is suggested at .00025 mg/1, which is one-
twentieth the concentration known to cause mortality in a two-day exposure
to the most sensitive group of organisms. Because of the non-accumulation
characteristics of this compound, and because this concentration allows for
a 250:1 application factor for a sensitive fish species, a short term ex-
posure at this concentration should be completely compatible with freshwater
fisheries and ecosystem productivity. The only departure from this level
is suggested for feeder streams, in which an allowable short-term maximum of
0.001 mg/1 is proposed. The upward deviation from Rohlich's (1972) pro-
posed maxima is based on the exclusively pulse-type concentrations likely
to occur.
ENDOSULFAN(6,7,8,9,10,10-hexachloro-l,5,5a,6,9,9a-hydro-6-methano-2,4,3-
benzo(e)-dioxathiepin-3-oxide; Thiodan)
This organochlorine insecticide is only used on ornamentals and on
specialty forest crops, such as Christmas trees. It is moderately persis-
tent, and is used for control of needle miner insects and others for which
extended effectiveness is needed. Its use is so limited that its consid-
eration here is a reflection of the concentration of those uses near human
habitation, and its potential for harm to fish if deposited in water.
Of all the insecticides registered for use on forest species, endosul-
fan may have the greatest potential for causing injury to fish from any
given application. Its use in Christmas tree plantations is superimposed
on a weed control system in which there is maximum opportunity for surface
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runoff, which is not normally an important route of stream contamination in
forests. It is moderately persistent, but has very low solubility. There-
fore, the principal route of entry into streams is likely to be through
sediment transport, in which form most of the material is not in solution.
Rainbow trout are extremely sensitive to endosulfan. The LC of
0.0003 mg/1 for rainbows indicates that the freshwater fishery is very vul-
nerable to contamination by this substance. Because of the potential per-
sistence of the chemical, low chronic levels are a possibility. In order
to minimize the likelihood of chronic exposure, the maximum concentration
of dissolved endosulfan in rivers is suggested at .000003 mg/1, the same as
proposed by Rohlich (1972), providing a concentration maximum with a 100:1
application factor. Because of the low solubility of endosulfan and its
infrequent use, it is unlikely that concentrations would build up in food
organisms if no pulse concentrations exceed this level.
Maximum concentrations in feeder streams are suggested at 0.00003 mg/1.
This maximum allows for short term peaks that are considerably below the
lethal level for fish. No greater allowance is suggested for safety be-
cause the other aquatic organisms are largely more tolerant of the insecti-
cide than are the fish that feed on them.
Monitoring of solution levels will require filtration or centrifugation
to remove adsorbed material prior to extraction.
ENDRIN (Hexachloroepoxyoctahydro-endo, endodimethanonaphthalene)
This chlorinated hydrocarbon insecticide has been used in forestry pri-
marily to protect directly sown conifer seeds from seed-eating rodents.
Endrin is low in water solubility and mobility. Quantities of endrin
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applied in this manner range from 2.5 to 10 gins per hectare, much less than
for most forest insecticides.
Endrin is extremely toxic to fish and fish food organisms, with 96 hr
LCLn's reported in the .0001 mg/1 to .003 mg/1 range. Mammals are somewhat
less sensitive (1-16 mgAg). Criteria will therefore be recommended to
protect aquatic communities.
Maximum concentration recommended for the smallest stream category is
.00005 mg/1. For intermediate streams, a much lower concentration of .00001
mg/1 is recommended due to endrin's potential for bioconcentration (Mount
and Putnicki, 1966). In large rivers, a .00005 mg/1 limit is proposed, for
the same reason, providing a 100:1 application factor for coho salmon. Be-
cause endrin is eliminated from fish soon after exposure ceases (Argyle et_
al., 1973) these limits should protect against disruption of aquatic communi-
ties. The large river criteria suggested here is slightly higher than that
recommended by Rohlich (1972). Centrifugation or filtration should be a
part of the procedure for water monitoring.
FENITROTfflON(0,0-dimethyl O(4-nitro-m-tolyl)phosphorothioate; Smnithion)
This insecticide is of the organophosphate group, closely related to
parathion in structure. In contrast to parathion, fenitrothion is only
moderately toxic to mammals, and the compound has been extensively used as
a substitute for DDT and parathion for this reason. Fenitrothion has been
applied to several hundred thousand acres under temporary registration to
control spruce budworm (Gooley, 1973) and is now fully registered. Many
million acres in eastern Canada have been treated with fenitrothion for the
same purpose.
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Feintrothion selectivity in forests is based on the generally low toxi-
city to mammals, with acute oral LDcn i-n rats being 250-670 mg/kg. Also,
fenitrothion was not generally found to be metabolized to fenitroxon, al-
though it depends for its insecticidal effects on the ability of insects to
make such a transformation (Miyamoto et al., as cited by Matsumura, 1975).
Toxicity to salmonid fish is sufficiently low that research has been
concerned with behavioral manifestations. Symons (1973) reported that 50%
of the young salmon exposed to 1 mg/1 for 16 hours ceased to maintain ter-
ritories. Wildish and Lister (1973) found a loss of hierarchical order
among brook trout which were fed a diet containing 10 mg/g of fenitrothion
for 4 weeks. When treatment ceased, fish behavior returned to normal in
both cases.
Since toxicity to fish is relatively low, the most likely effect of
this material would be to aquatic insect populations, for which toxicity
data are scant. Tracy and Purvis (1976) monitored the effects on aquatic
insects of applying 2 to 4- oz./acre ( .14 to .28 kg/ha) of fenitrothion to
portions of six forested watersheds in north central Washington. Buffer
strips along streams were not excluded. Peak fenitrothion concentrations
ranged from 1 to 30 ug/liter. At the highest measured concentration, 20%
mortality of mayflies occurred, but the only change noted at most sampling
sites was a temporary increase in the proportion of mayflies among drifting
live insects. An application factor of 200:1 is therefore recommended be-
low the lowest response level by fish. The recommended maximum in large
streams is therefore .005 mg/1.
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GUTHION (0,0-dimethyl S-(4-oxo-l,2,3-benzotriazin-3(4H)-ylmethyl)phosphoro-
dithioate); (azinphosmethyl)
This insecticide is of the organophosphate group with some residual
action and ability to penetrate skin. It is very toxic to rats and aquatic
organisms. Its limited use in forestry prevents substantial exposure of
any forest wildlife, but it may be used on Christmas trees and other orna-
mentals where opportunity for human exposure is greater. Considerable dif-
ficulty will be encountered in identifying pollution specifically related to
silvicultural uses, because it is widely used on orchard crops and seldom on
forest species.
Guthion limitations in water can be based on expectation of harm to
fish and aquatic insects. Among the most sensitive fish are salmon. -48-
hour LC 's for coho and chinook salmon are 0.005 and 0.0062 mg/1. Stone-
flies are more sensitive, with 96-hour LC5Q of 0.0015 mg/1. Differences in
exposure time have little effect on response to a given concentration sug-
gesting that the critical exposure period is brief. Criteria for small
streams should therefore be close to those of rivers. Numerous fish species,
especially those native to warm water, are apparently less sensitive than
salmon, and the rationale for setting criteria is based on food organisms.
On this basis, a maximum concentration in large rivers of 0.0007 mg/1 is
proposed. This concentration provides a 20:1 application factor for the
most sensitive known fish. Slightly higher limits are proposed for large
streams capable of supporting a freshwater fishery, and for feeder streams.
The character of this insecticide suggests that these concentrations would
cause little insect mortality, and would be of short duration. Rohlich
(19V2) recommended maxima of .000001 mg/1, much lower than is proposed here.
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His rationale is not clear for the extremely low level unless there should
be evidence that groups of aquatic insects are substantially more sensitive
than the stonefly. In this event, the above recommendation should be al-
tered accordingly.
LINDANE (Gamma isomer of 1,2,3,4,5,6-hexachlorocychohexane)
This organochlorine insecticide is one of the few in its group that has
appreciable solubility in water (10 mg/l). Its use in forests is limited to
application as a bark spray for control of bark beetles. The absence of
aerial applications virtually precludes its appearance in streams despite
its widespread use for control of the southern pine beetle.
Lindane is moderately toxic to mammals, with acute oral UX^'s in the
range of 60-127 mg/kg. Due to rapid metabolic breakdown, it has low poten-
tial for bioaccumulation (Koerber, 1976). The toxicity of lindane has been
investigated on a large number of fish and aquatic organisms. LC^'s range
from 0.002 to 0.083 mg/l for nine species of fish, with brown trout being
the most sensitive by a substantial margin. Stoneflies are also sensitive,
with LCLn of 0.0045 mg/l, 100 times more sensitive than Daphnia.' On the
basis that a prime freshwater fish is the most sensitive known non-target
species, it will be used to determine the criterion for limiting concentra-
tion.
In proposing 0.00001 mg/l as the maximum concentration in rivers, a
direct application factor of 200:1 is used. The very large factor is based
on the potential for chronic exposure at extremely low levels resulting from
the persistence of this compound and solubility properties that render it
capable of moving slowly into streams. Higher concentrations are proposed
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for large streams and feeder streams on the basis that they still provide
a margin of 20:1 or more, and their rates of flushing do not permit a sus-
tained elevated level. This level is the same as proposed in the QCW.
Although the use of lindane as a general insecticide is decreasing,
its use in other than forest operations far outshadows the very small amount
used for beetle control. Under the circumstances, the total contribution
from forest operations is subject to masking by other much larger sources.
There is therefore concern in setting criteria for forest use that monitor-
ing and enforcement pose serious practical problems in relation to the mag-
nitude of the potential danger from contamination by other uses. Therefore,
water sampling should be done both above and below projects along a stream,
if possible. Samples should be filtered or centrifuged to remove particles.
MALATHION (0,0-dimethyl phosphorodithioate of diethylmercaptosuctinate)
This insecticide of the organophosphate group is well known for its
safety and selectivity among terrestrial species. Because of its record of
safety, lack of persistence and utility as a general insecticide, malathion
may eventually find more general usage in forests, where it is used little
at present.
Matsumura (1975) describes malathion selectivity for mammals in terms
of the ability of the mammalian liver to break down the compound by removal
of its carboxyl group. Because of this ability, the acute oral LD-n in rats
has been reported at the high levels of 597 mg/kg to 5,800 mg/kg. Fish are
less sensitive to malathion than to many other insecticides, but are never-
theless quite sensitive. Ninety-six hour LC 's for fish among the salmonids
range from 0.1 mg/1 to 0.2 mg/1. Other fish in the same range include
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bluegill, redear sunfish, largemouth bass, and perch, while fathead minnow
and channel catfish show the surprisingly high 48-hour !Ł„ levels of 8.97
and 9.0 mg/1 respectively.
Long-term effects of malathion on fish have been studied "both in terms
of chronic toxicity and determination of no-effect levels. Some chronic
(10 month) effects were observed in fathead minnows and bluegills at con-
centrations approximately 1/15 of the 96-hour LC 's. Concentrations of 1/30
to 1/45 of the 96-hour LC5n produced no responses during exposures of 10-11
months. No-effect levels for the most sensitive fish have been identified
at 0.0036 mg/1.
The stonefly is apparently more sensitive than is any fish. The LC^Q
level (96-hour) for stoneflies is 0.01 mg/1. Daphnia is more sensitive,
with a 96-hour IS of 0.0018 mg/1.
The rationale for establishing a maximum concentration of malathion in
water is based on potential injury to aquatic food organisms. Because
malathion is non-persistent and non-accumulating, and because aquatic insects
have substantial ability to recover after some damage to their populations,
a smaller safety factor can be used than would be needed for a more persis-
tent compound. Moreover, the potential harm from a brief spike in a feeder
stream is small enough to permit the occurrence of such events at levels
approaching one fourth of the 96-hour LC levels without causing harm to
the freshwater fishery. Under the circumstances, application factors of
20:1 for Daphnia and 100:1 for stoneflies are proposed for establishing
maximum levels in rivers, leading to a recommended maximum of 0.0001 mg/1,
which is below the maximum suggested in the QCW. This maximum could be
raised in streams of feeder classes to 0.0005 mg/1 without increasing the
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likelihood of injury to the fishery, provided these exposures are limited
to 24 hours, and without risking dangerous levels in major rivers.
PHOSPHAMDON (2-chioro-2-diethylcarbamoyl-l-methyl vinyl dimethylphosphate;
Dimecron)
This systemic insecticide is one of the organophosphates used for
aerial control of forest defoliators. It is water soluble and non-persistent.
Although very toxic to mammals it is even less toxic to some fish than car-
baryl. Sensitivity of insects and crustaceans is variable, but some species
are much more sensitive than fish. Daphnia (water fleas) were the most
sensitive organisms tested (96 hr LC^ of .0088 mg/l) while crayfish were
more resistant than some fish species (96 hr LC_n of 7.5 mg/l).
Phosphamidon is not widely used in forestry at present but is being in-
vestigated as a substitute for DDT against defoliating insects. It may
eventually be applied over large areas, if found to be effective.
Criteria will be set to protect food species, since some of them are
orders of magnitude more sensitive than fish. A concentration of .0005 mg/l
in feeder streams would provide a 96 hr application factor of about 20:1
for the most sensitive species tested and 4-0:1 for the second most sensi-
tive species. Since this chemical is neither persistent nor cumulative,
limits for larger streams do not need to be much more stringent. A concen-
tration of .0002 mg/l provides nearly a 50:1 application factor for the
most sensitive species tested. This level is somewhat higher than that
suggested by Rohlich (1972) and is given on the basis of the excellent
safety record of this insecticide.
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TRICHLORFON (Dimethyl(2,2,3-trichloro-l-hydroxyethyl)phosphonate; Dipterex)
This insecticide is one of the organophosphate group used for aerial
control of defoliators, and is used agriculturally in animal feed (as a
bloodstream systemic) as well as to protect plants. It is effective against
insects because it converts to dichlorvos within the insect's digestive
tract. It is moderately toxic to mammals (LD^, 400 and 600 mg/kg for rat
and mouse, respectively) and is rapidly excreted in urine. Toxicity to in-
sects and crustaceans is 10-1000 times greater than for fish, therefore
criteria will be recommended so as to protect fish food organisms rather
than the fish. Toxicology of trichlorphon itself is similar to phosphamidon
and the same concentration for feeder streams is recommended. Because
trichlorphon is converted to dichlorvos (which is much more toxic to crus-
taceans and somewhat more so to fish) under mildly alkaline conditions
(pH 7 and above) much more stringent limits have been set for larger streams.
A maximum concentration of .00005 mg/1 for large streams provides a small
safety margin for the most sensitive crustacean tested and a 5 to 10 fold
margin for the majority, assuming complete conversion to dichlorvos. Since
most forest streams are acid, this margin is considered conservative.
Trichlorphon has been tested against gypsy moth and spruce budworm on
an operational scale. A possibility therefore exists that it may be applied
to very large areas if these test results favor it over other insecticides.
The recommended concentration limits by Rohlich (1972) proposed a maximum
of .000002 mg/1. The presumption is made that such stringent limits are
proposed to protect against alkaline conversion. On this basis, the .000002
mg/1 limit is supported for streams having pH of 7.0 or greater.
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CHAPTERS
BEHAVIOR OF CHEMICALS
USED IN SILVICULTURAL OPERATIONS
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BEHAVIOROF CHEMICALS USEDEVSILVICULTURALOPERATIONS
Toxic hazard and other adverse effects of chemical pollution have been
described principally in terms of concentration in water, and duration of
elevated levels. Maintenance of water quality will depend on use patterns
which result in minimum entry of chemical into streamflow, and minimum
harmful effects from any chemical that inadvertently reaches the water.
Operational guidelines for chemicals have several important points at
which control is exerted over the probability that harmful effects to aqua-
tic systems and users will occur. These are l) control over the proximity
of application to streams, 2) control of dispersion from application equip-
ment, and 3) control over choice of chemical, hence mobility and ability
for a given application rate to cause damage. The effectiveness with which
these controls are prescribed depends on characteristics of the equipment,
chemical, and the environment into which it is introduced. Specific control
guidelines must be grounded on scientific evaluation of interaction among
physical, chemical and biological systems combined with observational exper-
ience gained from monitoring chemicals and affected biota. The purpose of
this chapter is to review the behavior of the applied chemicals, and to pro-
vide guides as to where and how the chemicals can be applied without affect-
ing water quality.
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Physical Properties of Silviculture! Chemicals
in Relation to Mobility in Soil
FERTILIZER
The elements added to forests as fertilizers occur there naturally in
living and dead vegetation and in the soil. Fertilization attempts to in-
crease plant production by providing essential elements such as nitrogen,
phosphorus and potassium in forms more available to rapidly growing trees
than those already present. There are many forms in which the various
fertilizer components are partitioned within the forest ecosystem.
Urea is the most common nitrogen fertilizer applied in the Pacific
Northwest. A coarse, granular "prill" form is used to minimize drift and
maximize crown penetration during aerial application. Although urea is very
soluble, it is rapidly hydrolyzed to ammonia, which is adsorbed by soil
particles or taken up by living plants as ammonium ion. Urea is thus an im-
portant form of nitrogen in stream water for only a few days immediately
after it has been applied. Under abnormally dry conditions Watkins and
Strand (1970) reported that as much as 46$ of the added urea may be lost
directly to the atmosphere as ammonia, and it is therefore usually applied
when temperatures are low and rain will carry it into the soil.
Under conditions of normal aeration and moisture, much of the urea is
gradually converted to nitrate by soil baceteria. In this form, nitrogen
is rapidly taken up by growing vegetation. Nitrate not taken up by plants
remains in equilibrium with ammonium and organic nitrogen which can also
be utilized by plants. Toxic amounts of nitrate in soil are unknown in
forests (Miller, 1974). Any excess of nitrate not assimilated
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by plants may be leached into streams, however, due to its high solubility.
Free-to-grow ecosystems are effective sinks for nitrate, however, and
leakage is minor. Under poorly drained circumstances, especially where a
high water table prevails, denitrifying bacteria may result in significant
production of nitrite, which is a form much more toxic to fish.
Ammonia is added directly in some fertilizer forms or can occur as a
breakdown product of urea. Ammonia is a form of nitrogen with substantial
toxicity to fish under certain circumstances. Only unionized ammonia is
toxic to fish and QCW describes this form as important only in warm, alka-
line waters. Forest streams are usually neutral or acid (strongly acid in
southeastern and north central U.S.) and are relatively cool. The range of
total ammonia concentrations resulting from forest fertilization in the
Pacific Northwest does not approach the critical level set by EPA.
Phosphates are rapidly adsorbed by several common soil colloids, such
as clays and oxides of iron and aluminum. In this state they are only very
slightly soluble, and leaching through soil becomes insignificant. Most
soils have the capacity to tie up in this manner many times the quantity of
phosphate which foresters are likely to apply (Powers et al. 1975). Growing
vegetation is normally able to take up phosphate as fast as it becomes avail-
able . There are some soils of low surface adsorption capacity in which
phosphate can remain in solution subsequently subject to removal by
leaching. Phosphorus fertilization is now widely practiced on soils with
low phosphate retention capacity and on those with very high phosphate fix-
ing potential in the southeastern United States (Pritchett and Gooding, 1975),
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PESTICIDES
Mobility of pesticides in soil depends on solubility, adsorption and
persistence. Water movement is the driving force. In order for a silvicul-
tural chemical to reach surface or ground waters by passing through soils
it must be relatively soluble in water, resistant to adsorption by soil and
organic matter particles, and sufficiently persistent to endure until it
enters the water. Currently registered silvicultural pesticides do not com-
bine these necessary characteristics.
A few examples may illustrate how this chain of requirements works in
practice. DDT, although one of the most persistent pesticides, was detected
only in the upper few inches of soil in Canadian forests which had received
aerial applications for many years (Yule, 1970), because of its very low
solubility. Cacodylic acid, on the other hand, is very soluble, but is ad-
sorbed so tightly to mineral soil that it fails to penetrate more than a
few inches (Norris, 1974). The organo-phosphate insecticides and carbaryl
do not persist long enough to be leached through soil in significant con-
centrations. Phenoxy herbicides are degraded as well as adsorbed by soil
particles. Picloram is the only herbicide which is both sufficiently solu-
ble and persistent to allow measured concentrations to reach stream water in
subsurface flow, and these concentrations are very low.
Routes of Chemical Movement Into Water
Aerially applied forest chemicals are initially distributed among the
four sectors of the forest shown in Figure 5 : air, vegetation, forest
floor, and water. The proportion entering each compartment depends on the
nature of the chemical and carriers applied, method of application and
110
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environmental factors during and immediately following application. Ground
application is unlikely to cause direct contamination except through washing
of equipment or spillage.
In order to influence water quality directly, silvicultural chemicals
or their end products must reach a lake, stream or swamp (Figure 5). This
occurs principally "by direct application to the water while applying the
chemicals, inadvertantly or otherwise. Surface movement of recently applied
chemicals into the nearest stream by overland flow is another potential
route for contamination. Leaching of dissolved chemicals through the soil
to a water table and from there to the nearest surface water, is both a less
direct and less likely path to pollution. Erosion of soil which has pre-
viously been treated with pesticide can also carry chemical constituents to
water.
Distribution of pelleted fertilizer will result in maximum placement
on the forest floor, with little if any in the other three sectors. Spray-
ing of liquids from aircraft, on the other hand, may result in significant
atmospheric losses, possible drifting, potential water contamination and
reduced quantities reaching the forest floor. As little as 25 to 40% of a
low-volatile ester herbicide has reached its immediate target area when
applied from a fixed-wing aircraft. Similar percent recoveries have been
reported for aerially-applied insecticides (Argauer et_ al_., 1968; Tarrant
et al., 1969). Recent developments in drift control technology have de-
creased losses substantially.
Pesticides reaching the litter layer, or forest floor, are subject to
degradation at varying rates. Norris (1970) has investigated degradation
of four herbicides widely used in the Pacific Northwest. In red alder
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INITIAL RATE
DOES NOT
REACH
TARGET
( AT 10-200 FT 5_75o/
ABOVE CANOPY) 3 /0
CANOPY ON HILLY FOREST-
VEGETATION
\VIA L
ITTER
GROUND
METABOLIZED
STORED
DECOMPOSED < 25-95%
OPEN WATER
MAMMALIAN CONSUMERS
DECOMPOSED
DILUTED
DECOMPOSED
PASSED
.l %
.l %
GROUND WATER
FiglireS. Schematic diagram showing the distribution of aerially applied
chemicals in forests.
112
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forest floor material he found that 94 percent of the 2,4-D and 80 percent
of amitrole added were degraded in 35 days, while breakdown of 87 percent
of the 2,4,5-T required 120 days. Only 35 percent of the picloram was de-
graded in 180 days.
Comparison of recovery rates among various formulations of 2,/4-D in
red alder forest floor material revealed that approximately 25% of the
triethanolamine, isooctylester and solubilized acid forms were degraded in
15 days (Norris, 1970). More than 50% of the pure acid form was broken
down in the same time.
Degradation of 2,4,5-T from red alder forest floor material was approx-
imately 85% in 120 days, regardless of application rate. Breakdown of the
phenoxy herbicides is largely due to micro-organisms. Amitrole is decomposed
by chemical means as well.
That portion of an herbicide which is not decomposed on the forest
floor and washes into the soil is quickly adsorbed on to soil organic mater-
ial in the surface layer of forest soil. Herbicides held by organic matter
in this way are very resistant to leaching and continue to be decomposed by
micro-organisms.
Reported instances of significant stream contamination by forest insect-
icides have been the result of direct application to streams or atmospheric
drift. Low rates of application and low soil mobility make it very unlikely
that forest insecticides would pass through forest soils in amounts sufficient
to result in damage to aquatic biota.
Much of the forest fertilizer lost in drainage water has resulted from
chemicals falling directly into stream channels within the treated area.
Numerous studies have shown that concentration of dissolved fertilizer (urea)
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in streams within the treated area is highest immediately after application
(Moore, 1975). The size of this application-related peak concentration in
drainage water is reduced when care is taken to avoid dropping fertilizer
directly into stream channels. Due to the short-lived nature of these peak
concentrations and the small percentage of any potential treatment area oc-
cupied "by flowing water, a very small fraction of the total fertilizer
applied is lost in this manner; nearly all is in the form of urea at the time
of application.
Urea fertilizer is converted to nitrate, ammonium ion and organic ni-
trogen soon after application. That some nitrate constituent can eventually
pass through soil into surface waters is shown by a secondary peak concen-
tration (nitrate), which usually occurs when soils become saturated for the
first time after fertilizer has been applied (Figure 6). Most of the fer-
tilizer loss in the Pacific Northwest occurs in this form because slightly
elevated nitrate levels in solutions may last for several weeks or months.
Leaching and stream discharge rates associated with warm fall rains are apt
to be higher than when fertilizer was applied (Moore, 1971).
Influence of Application Method on Stream Contamination
Direct contamination of streams occurs through various routes, the im-
portance of which differs with method of application. In general, aerial
application has the greatest potential for uncontrolled movement of falling
droplets into open water. This is the logical result of widespread use, and
a substantial component of fine droplets usually resulting from conventional
nozzles operated 50 or more feet aboveground. This diffuse movement of small
quantities of material usually results in some deposit in water near the
114
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1.5
2
O
cc
l-
5 0.5
o
z:
o
o
0
1 I I
1 I
I I
UREA-N
NITRATE-N
J J A S 0 N D
TIME, MONTHS
J F M
6. Graph showing representative fluctuations of urea-N and
nitrate-N concentrations in streamwater following fertiliza-
tion of a coniferous watershed in western Oregon with 200
Ibs/acre (224- kg/ha) of urea (Fredriksen, Moore and Morris,
1975).
115
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operation, whether detectable or not. These low-level contaminations may
be decreased by modifying both equipment and the manner of use. Aerially
applied pesticides are usually loaded either at an airport or on an ele-
vated heliport some distance from open water. There is therefore little
chance for contamination through mishap while loading. Leaving streamsides
untreated prevents large droplets from contaminating. Contamination from
this source is of low level in most instances.
Ground application embodies a different set of problems, leading pre-
sumably to different patterns of contamination. Ground applicators are more
likely to be mixing and handling technical concentrates near water supplies
where spillage poses a contamination hazard. Users of injectors carry the
concentrate on their persons, and pose the possibility of contamination if
they fall while crossing streams. In general, however, most of these post-
ulated problems are subject to control through training and supervision.
The control of aerial contamination may entail technical modifications
according to the nature of the application job. Aircraft normally apply re-
latively low volumes of spray per unit area. Volumes range from about one
pint per acre (one liter per hectare) to 20 gallons per acre (187 1/ha).
The volumes greater than 3 gallons per acre (27 1/ha) are generally used for
herbicides requiring volume for penetration or suspension of wettable pow-
ders. Insecticides usually use low-volume applications.
As volume per acre decreases, the droplets must decrease in size if
coverage is not to be diminished. Because small droplets remain suspended
in air longer than large ones, they are more subject to drift, turbulence
and movement away from the swath centerline. This is an advantage for
116
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uniform coverage between streams, but it poses a contamination problem in
proximity to open water.
Fine droplets occur in almost any spray pattern. It is therefore dif-
ficult to eliminate them altogether. The proportion of volume in small
droplets is substantially controlled by spray boom pressure, nozzle tech-
nology and the use of various thickeners. The degree to which fine droplets
are minimized determines the proportional decrease in contamination with
increasing width of streamside buffer strips. Fines are kept to a minimum
by: l) reducing boom pressure, 2) increasing orifice size, 3) orienting
nozzles into the air stream, 4) using specialized boom and nozzle designs,
5) minimizing use of straight oil in spray mixtures, and 6) thickening the
spray mixture by addition of various foaming agents, thickening polymers or
inversion of emulsions.
The proportion of fine droplets determines certain features of the
application deposit rates across a swath. In general, a given aircraft
will produce a wider effective swath with fine sprays than with coarse
atomization, and there will be fewer gaps or peaks within the swath. The
outer edges of the swath that overlap with the next swath or extend into
an untreated zone also carry a higher deposit, whereas a coarse spray has a
sharper edge to its pattern. Even apart from drift, a pattern with fine
droplets must therefore be farther away from open water than a coarse spray
to achieve a given level of pollution control.
For a given volume of spray an increase in droplet size is accompanied
by a decrease in coverage. If this is to be done without a decrease in ef-
fectiveness, higher application rates of pesticide may have to be used.
There are therefore incentives for optimizing droplet size to meet control
117
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requirements and reduce risk of contamination. Ideally, this should be
done by creating uniform droplets of the smallest size compatible with
expected air movement and flying height.
The above brief review of application technology is not intended to be
an in-depth review of the technical literature. Readers interested in
technological aspects of controlling droplet distribution are referred to a
substantial body of literature in the agricultural engineering area of ap-
plication systems. This literature will be sampled below to review the use
of application technology for determining swath widths and influence of buf-
fer strips on deposits of chemicals.
Total swath width in an aerial spray is considerably wider than effect-
ive swath width (ESW). The latter is defined as the maximum width covered by
contiguous successive swaths spaced so that deposit deficiencies are not ob-
served at the points of overlap. Actually, most points within a sprayed area
are covered by a swath of nominal application rate plus the "tails" of sev-
eral other swaths (Isler and Maksymiuk, 1961; Isler and Yuill, 1963). These
tails help to minimize skips in application pattern, but are the principal
source of stream contamination apart from direct flyover. The amount of
such deposits can be estimated from research on swath cross-sections, and
from the limited field measurements of cumulative deposits.
The deposits outside the effective swath width have been described for
Stearman aircraft flying 50 feet above a target (Isler and Yuill, 1963).
Using an aircraft calibrated to deliver one gallon per acre in a 100-foot
ESW with 150 microns mass median diameter (MMD), they observed that the
deposit 100 ft. (30 M) from the centerline were one-fifth those at 50
feet (.15 M), and one tenth the nominal application rate. This relation
118
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was nearly constant for several arrangements of booms, and nozzles within
booms. Recovery rate of total spray ranged from 60 to 90 percent within
a double swath width. Extrapolation of these data suggests that a buffer
strip of one full swath'width would expose a stream to a range of deposit
varying about five percent of the nominal rate. Isler and Maksymiuk (1963)
observed a similar distribution of droplets of unspecified size applied
at the same rate by helicopter. The fixed-wing tests were with water; heli-
copter tests were done with oil.
Some of the most definitive data from operational high-volume herbicide,
sprays (10 gallons per acre) were obtained from unpublished results in an
Idaho aerial brush control operation. Mr. Paul Gravelle, Potlatch Corpora-
tion monitored herbicide deposits downwind of a helicopter application of
phenoxy herbicides in a water-oil invert emulsion. His findings are shown
in Figure 7, in which the deposits are plotted as the function of distance
from the edge of a major (200-acre) spray project. Deposits were recorded
downwind when wind velocity during the project varied between 1-10 mph. Two
major patterns emerged from his data: l) deposits were less than five per-
cent fifty feet downwind of the project edge, and 2) virtually all deposits
outside the project were of droplets <_ 250 microns mass median diameter.
Gravelle's data indicate that important gains to be made from buffer
strips are limited to the first 50 feet, beyond which there is a very low
incidence of deposit, varying little with additional distance. The low
level deposits observed could probably have been largely eliminated with a
nozzle system that minimized droplets below 250 microns. In view of the
dependence of insecticide applications on low volumes and small droplet
sizes, the need for wider buffer strips can be visualized.
119
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80
• 1
' 1 1
DIAMETER
o r
DOSAGE
o_
o
I
800 en
z:
o
cc
600 r
400
200
0
CŁ
LU
h-
o
CO
o
o.
UJ
Q
200 400
DISTANCE FROM TARGET AREA, FEET
Figure 7. Percentage of nominal dosage reaching the ground, and mass
median diameter of an herbicide deposit outside of and downwind
from a 200 acre spray project, applied by helicopter at 10 gal-
lons per acre water-oil emulsion in 1-10 mph crosswind. (From
Gravelle, 1976, unpublished data, Potlatch Corporation,
Lewi s ton, Idaho.)
Environmental Factors Affecting Appearance
of Sflvicultural Chemicals in Water
Nature and distribution of precipitation is perhaps the most widely
recognized environmental influence on non-point water pollution. Stewart
et_ al_. (1975) have emphasized the primary role of rainfall in their compre-
hensive summary of factors affecting potential non-point water pollution
from agricultural sources. Although the amount of erosion from forest land
120
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is much less than that due to agriculture, precipitation is still a dominant
influence. Torrential rainfall soon after application of chemicals to
forest lands is obviously more apt to result in polluted runoff that! low
intensity, intermittent rains which begin several weeks after a similar ap-
plication.
Length and steepness of slope has less influence on pollution from
forested watersheds than from agricultural lands because little or no surface
runoff takes place in forests, except where soils have been severely dis-
turbed (Dyrness, 1969).
Perhaps a more important environmental factor than slope is the nature
and distribution of ground and surface water. Forest waters are most
likely to show elevated levels of silvicultural chemicals in nearly level
areas where a water table approaches the surface and small streams or swamps
are numerous. Such contamination can occur either because of difficulty in
avoiding direct application to surface water or because chemicals reach
ground water as soon as they penetrate the soil.
Forest soils provide a large safety factor with respect to water pollu-
tion by silvicultural chemicals. Those pesticides which persist long enough
to be washed from vegetation and through the forest floor material are
quickly adsorbed onto the surface of minute soil particles, where a large
variety of micro-organisms are capable of decomposing most of them. Organic
debris in streams has a similar tendency to remove solutes from water.
The surface area on which chemicals may be adsorbed in soils is indeed
large and occurs on both organic matter and clay particles. The organic
matter content of forest soils commonly ranges between 50,000 and 500,000
pounds per acre (56,000 and 560,000 kg/ha), which provides a surface area of
121
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4,000 to 40,000 sq. mi./acre of soil (25,000-250,000 Km /ha), if one assumes
2
an average of 500 m per gram of soil organic matter (Bailey and White,
1964).
The specific surface of clay is somewhat more variable, but may range
higher, and the clay content of forest soils is commonly several times that
of organic matter. It would not be at all unusual then, for a forest soil
to contain internal surface area more than double the values cited above.
In addition to surface area, clay and organic matter has a negative electric
charge which enables it to attract those chemicals which are positively
charged, e.g. ammonium ions and cacodylic acid. Values at the lower end of
the range given above are to be expected in the sandy soils of the south-
eastern U.S., while those at the higher end would be most common in coastal
areas of the Pacific Northwest.
Exceptions to the general effectiveness of soil adsorption for immo-
bilizing forest chemicals are of two kinds. Very soluble materials such as
nitrate can be leached from soils if there is abundant rainfall when both
vegetation and soil organisms are inactive or have been disturbed. Repeated
use of persistent chemicals such as DDT, will allow them to accumulate to
some degree in soils where application inputs occur faster than micro-
organisms can destroy them. These chemicals are prevented from leaching out
of soil, but are still subject to water transport by erosion, if soil is dis-
turbed.
Patterns of Appearance of Sflvicultural Chemicals in Water
Figures 6 and 8 illustrate the essential similarity among concentra-
tion curves reported for silvicultural chemicals in waters draining treated
122
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0
20 40
TIME, HOURS
60
Figure 8. Graph showing a representative pattern of pesticide concentration
in streamwater after spraying 10 percent of a forest watershed in
4 separate portions (Norris, 1967).
areas. Levels tend to be highest immediately following application of the
chemicals (several hours to several days), then quickly drop to much lower
concentrations, from which there is a gradual decline over a period of days
(herbicides) or months (fertilizer). The amount of time involved is influ-
enced by velocity of the streams concerned and regularity of the curve is
influenced by precipitation. Alternation of wet and dry periods, for in-
stance, may cause significant concentration fluctuations in chemicals of
some degree of mobility.
123
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Maximum reported concentrations following forest fertilization are 27
and 44 mg/1 of nitrogen as urea (Cline, 1973; Burroughs and Froehlich,
1972). In both instances, small streams were not protected by untreated
buffer strips. In the latter case, all of the watershed was treated.
These values are close to theoretical expectations for a stream one foot
deep receiving the rate applied (200#/acre of N) (224 kg/ha). An average
peak value for watersheds receiving corresponding treatment is approximately
1/10 of those given above. Where only a fraction of a watershed was
fertilized, and buffer strips were excluded, the maximum urea-N value was
commonly less than 1 mg/1 (Moore, 1975).
Peak ammonia-N concentrations for unbuffered streams ranged between
.35 and 1.4 mg/1, while buffered and partially treated watersheds gave
corresponding values between .01-.16 mg/1. The highest of these values is
well below those cited as harmful to freshwater aquatic species in QCW, at
expected conditions of temperature and pH. Peak values for nitrate-N in
streams lacking buffer strips was 1.8-2.1 mg/1 as opposed to 0.4-.17 mg/1
in partially treated watersheds with buffer strips.
Nitrate concentrations vary widely in natural streamflow. Brown et_ al.
(1973) and Miller (1974) have examined the variation in nitrate levels in
streams subjected to various perturbations in the nitrogen-rich forest
soil systems of the Oregon Coast Range. Fredriksen (1970) has reported
similar data from a less rich group of watersheds in the Oregon Cascades.
All these reports identify considerable variability in native nitrate con-
centrations unrelated to application of fertilizers. With rare exceptions, native
124
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water fertility exhibits greater variability than was reported by Moore in
his review of existing water impact data relating to fertilization (1975).
Data on water quality changes from forest fertilization with phosphates
is limited. Those studies which have been completed indicate little or no
direct effects. Sanderford (1975) reported a slight decrease in actual
phosphate concentrations after fertilizing a loblolly pine plantation in
the North Carolina piedmont. Compensating increases in stream flow resul-
ted in slightly higher loss of phosphorus per unit area. Since only one-
eighth of the watershed was fertilized, the increased phosphorus loss could
not be positively attributed to the fertilized area.
Data from the Carolina Coastal Plain and from northern Florida indi-
cate that phosphate levels in water draining those forested areas are very
low, and are not measurably influenced by fertilization in "bedding" oper-
ations. This monitoring was done after applications of 0-<49-0 fertilizer,
ranging from 50 to 200 pounds per acre (56 to 22<4 kg/ha) applied as part
of large industrial rehabilitation projects, all by ground equipment
(personal communication, Mr. George Dissmeyer, U.S. Forest Service, Atlanta,
Georgia).
Application of approximately 100 pounds per acre (112 kg/ha)-of phos-
phate to coastal pine forests in western Florida resulted in small and ir-
regular changes in phosphate concentration of local streams. Post-treat-
ment ranges did not exceed the previously established normal range (Avers
and Scott, 1976). One of the nine watersheds monitored showed a significant
increase in phosphate concentration (from .03 to .06 ppm) for about one month
after fertilization. The authors indicate a high probability that this in-
creased concentration resulted from fertilizer being spread on open waters
125
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due to their intricate pattern in this drainage. Approximately one half of
one percent of the applied phosphate was accounted for in stream flow.
Dr. William Pritchett, of the University of Florida, Gainsville,
(personal communication, April 30, 1976) described phosphates, applied in
the soluble form, as increasing the concentration of soil solution phos-
phorus to levels above 1 ppm for several months in flatwood soils (low in
phosphorus retention capacity). However, most of these soils have spodic
horizons, which are capable of fixing high levels of phosphorus, and there
appears to be little danger of loss of phosphorus through the ground water.
In order to minimize this possibility, less soluble forms of phosphate
(ground rock phosphate) are recommended in the flatwoods. In his opinion,
applied phosphate does not appear to be a significant pollutant when used
in the flatwoods at ordinary rates of application.
Season of application influences the potential for toxic hazard of
pesticides. Water velocity varies from season to season, and spawning of
sensitive species is seasonal. The broad array of herbicides and seasons
of plant sensitivity as well as low toxicity permit a broad range of low-
hazard vegetation control. The limited season of target insect sensitivity,
however, is a strong constraing on flexibility of insecticide use.
Relation Between Concentration of Chemical
in Water and Biological Activity
The general relations between chemicals and aquatic organisms are de-
pendent on concentration and duration of exposure. Other factors in the
aquatic environment can interact to influence the exposure/response rela-
tionship. Fertilizers and pesticides react in different ways, and have different
126
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effects on ecosystem structure and function. These groups of chemicals will
therefore be discussed separately in this section.
FERTILIZERS
To review the pattern of entry, aerially applied fertilizers usually
appear in water as urea, nitrate or phosphate. Of the various forms of
nitrogen, nitrate is the principal mobile form, and is the form most often
encountered in forest watersheds other than the urea which happens to fall
in open water. For practical purposes the other forms of nitrogen can be
ignored.
Concentrations of nutrients in water influence stream productivity.
The time interval over which concentration is expressed translates into a
total quantity of nutrient passing a given point in the stream. In the
absence of toxic quantities, the effect of increasing fertility over a per-
iod of time is to increase productivity of both resident and drifting plants
during the period of elevated concentration. Aquatic plants are good
scavengers of nutrients, and the elevated nutrient concentration cannot be
expected to last as water moves downstream. The nutrients can move down-
stream, principally as increased biomass of algae, if not harvested by
fish. In cases of long residence in impoundments or ponds, this can give
rise to an algal bloom, with possible subsequent harmful effects on dissolved
oxygen concentrations as plants die.
Major increases in aquatic plant biomass require sustained increases in
nutrient levels. The finding that nutrient input from forest fertilization
occurs as pulse contaminations (Moore, 1975) is basic to an evaluation of
the likelihood of adverse effect on aquatic life. It may be postulated that
127
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a graphic representation of such chemical fertilization on biomass and
productivity of aquatic systems would take the form illustrated in Figure
9.
In Figure 9, it will be observed that a brief change in productivity
does not have a prolonged effect on ecosystem dynamics. A pulse of ferti-
lizer passing a point in a stream contributes to a brief increase in pro-
ductivity, which leads to the accumulation of an increment of biomass. As
soon as the pulse passes, excess accumulation ceases, and the only result
is a somewhat higher standing crop. Because of the general nutrient
economy of free-respending ecosystems, it may be anticipated that the added
increment of nutrient in the local pool will equilibrate back to its original
level very slowly. The brief nature of the increased period of productivity
suggests that there is not likely to be a substantial change in ecosystem
structure associated with the occurrence of a pulse of fertility. In the
event of a low-level, but prolonged increase, e.g. the nitrate in Figure 6,
the pattern of impact on productivity would presumably follow the dashed
line in Figure 9.
The effect of a pulse of fertility in a forest stream system will
likely decrease with increasing distance below the fertilization project.
Pulses of contamination in water change with downstream movement. Studies
with various chemicals, including dyes and herbicides, suggest that down-
stream movement decreases concentration, and increases duration of detect-
able concentration (Norris, 1971; Muirhead-Thpmson, 1971). This pattern
presumably would occur with nutrient contamination, but the effect of con-
tamination with nutrients would be lost even more quickly than with pesti-
cides. The rapid loss in effect would result from scavenging of nutrients
128
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CO
CO
<
2
O
CD
FERTILIZED
o
ID
Q
O
o:
CL
FERTILIZED
TIME
TIME
Figure 9. The postulated effect of fertilization on stream biomass and pro-
ductivity.
from the water by roots and aquatic plants, by dilution and by attenuation
from the native nutrient pool to which ecosystems have already adjusted
themselves.
Water quality effects of forest fertilization on streams within the
area treated depend largely on concentration of fertilizer components in
the water. Lakes or estuaries which receive these stream, ^..^ve
capable of biologically accumulating substances in solution - c ..ub
Consequently, the total amount of fertilizer which is lost from a
over a period of time may have as much significance for eutrophication in
impoundments and estuaries as the concentration in drainage water at any
given time does within the forest being fertilized.
Forest ecosystems are noted for the efficiency with which they retain
nutrients. Several authors (Fredriksen, 1972; Bormann et al., 1969; and
are
129
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Schrieber et^ al_., 1974) have reported that forest watersheds retain much of
the nutrients added in rainfall. The net result is that levels of N and P
tend to build up in forests and forest soils with the passage of time. The
forms in which these elements occur in soils and vegetation are not readily
soluble, and they therefore pose no direct threat of increased water pollu-
tion.
It is not surprising then, that very little of the fertilizer applied
to forests is lost in drainage water. Moore (1971, 1975) reported losses
ranging from .17 to .25$ of that applied, during one year and seven months,
respectively, for coniferous watersheds in western Oregon and Washington.
Those values are equivalent to approximately .5 pounds/acre/year (.55 kg/ha/
yr) and are only one quarter the increased nitrogen losses reported by
Fredriksen (1970) following normal logging practices in the Northwest.
Maximum frequency of nitrogen fertilization in the Northwest is pre-
sently once in five years. In the southeastern states the interval between
phosphorus fertilizations is several times longer. As currently practiced
only a small fraction of a forested watershed is fertilized in a given year.
Presently available evidence does not implicate forest fertilization in
significant eutrophication. Data are lacking, however, to determine the
long term effects of wide scale fertilizer application on stream water
quality.
The area loading concept of Vollenweider (1975) implies that eutrophi-
cation potential is always relative to the hydrodynamic characteristics of
the water body being studied. That is, not only concentration and total
amount of nutrient added, but those factors in relation to size and
130
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flushing rate of the pond or lake being considered, determine whether
detrimental accumulations of nutrients occur.
As long as even small amounts of forest fertilizers find their way to
water, the possibility of causing eutrophication somewhere downstream can-
not be entirely dismissed. Small lakes with large watersheds,and which
receive a small annual flow of water, would be the most likely to experience
eutrophication if a major part of that watershed were fertilized.
PESTICIDES
Pesticides display early patterns of concentration similar to those of
fertilizers. They differ in the important respect that they do not appear
in subsequent runoff, however. Pulse-like patterns are similar to those of
fertilizer after aerial application, but amounts involved are very much
smaller. They are not likely to be superimposed on aquatic systems in
which baseline concentrations may be much higher than the amount added, and
they represent a new effect on ecosystems. The potential for changing eco-
system structure therefore needs to be examined. Basic to an evaluation of
potential impact is a picture of the relation between observed concentrations
and estimates of "no effect" levels for each major group of species exposed.
Concepts of toxicity and toxicology are discussed in Chapter 4 of this
report in the development of water quality criteria. It is germane to con-
sider here the spectrum of toxicity, however, so that a perspective can be
maintained regarding impact on a complex ecosystem when one group of spe-
cies is affected more than another.
A peak of pesticide contamination entering a stream can place a selec-
tive pressure on entities within ecosystems, resulting in a change in
131
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structure. If the concentration^' re suiting from a spray operation is far
enough above the no-effect level for the most sensitive group of organisms
so that it causes mortality or seriously abnormal function, the effect on
the structure of an aquatic ecosystem is through temporary removal of part
of a stratum. The duration of this hiatus, as well as degree, influences
the likelihood of an important general ecosystem response. Insecticides
tend to directly affect the animal community only, especially the insects
and fish; a change in aquatic plant consumers could have an effect on the
aquatic plant community. Herbicides, on the other hand, have the potential
for influencing plants with no direct effect on insects or fish, but major
changes in plant community structure can have severe and prolonged effects
on consumers. Any prediction of effect on aquatic ecosystems must there-
fore consider total exposure of each major component of ecosystems sub-
jected to pesticide. An estimation of the effects on susceptible species
can then be made in relation to their influence on the rest of the eco-
system. A graphical portrayal of sensitivity of groups, and the distribu-
tion of species sensitivities within groups as in Figure 3, Chapter 4 is
helpful in analyzing potential impact on community structure.
The low chronicity of pesticides applied by aircraft in silvicultural
practices is significant in searching for harmful effects. Organisms of
various groups can be expected to respond shortly after exposure, if symp-
toms are to be expressed at all. If effects are sublethal, recovery can be
expected without long-term impairment of function in the way of a person
recovering from toxic drugs. Even if some organisms are killed, populations
of survivors can be expected to recover in accordance with the carrying
capacity of their ecosystem, provided the exposure is transient. If
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exposure were prolonged, effects of chronic exposure would express them-
selves in a prolonged restructuring of the system, with dominance ex-
pressed by resistant or tolerant groups, including impacted species
becoming genetically adapted to the particular adversity (Muirhead-
Thomson, 1971).
The characteristic decrease in peak concentrations of pesticide pollu-
tants with downstream movement reduces the likelihood of ecosystem impact
with increasing distance below the project. The probability of direct harm
is therefore greatest within the operating unit, and close to the downstream
edge. This probability can be expressed in terms of the degree and duration
of a concentration curve that lies above the threshold of effect (Figure 10).
Figure 10 illustrates a pattern common to all classes of chemical ap-
plied directly to open streams. The difference in effect is determined by
the amplitude of the harmful effect level, and by the spectrum of species
affected. Recalling the 24-hour maxima recommended for 2,4,5-T (< .06 mg/l),
if the threshold of effect for a 24-hour exposure were one fifth the 24-hour
LCcn of 1.4 mg/l for the most sensitive species, or 0.28 mg/l, then the
herbicide would have no effect either in the area treated or downstream.
If the material were an insecticide with a threshold of .01 mg/l, for
aquatic insects, but 0.1 mg/l or higher for all other groups of organisms,
contamination at 0.02 mg/l would produce a short term of injurious effects
to insects and their predators within the treated area. These effects would
largely be confined to reaches within and close to the area treated. An
insecticide with a threshold of 0.0003 mg/l for rainbow trout would clearly
cause serious mortality among trout and related organisms substantially
below the lower monitoring point, if introduced at similar concentrations.
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O
h-
oc
LU
O
2
O
O
100
TIME, MINUTES
200
Figure 10. Comparison between chemical (dye) concentrations in stream
water at the area of application (station l) and a point
downstream (station 2). Adapted from Muirhead-Thomson, 1971.
If threshold of effect on the most sensitive organisms were
1 mg/1, there would be no effect discernible at Station 2.
Interaction Between Chemicab and Stream Environment
The aquatic environment exerts a substantial influence on the potential
for harmful effects from chemical pollution. Among the more important
factors are streamside cover, water depth at the point of contamination,
stream bottom characteristics, stream velocity, degree of aeration, suspended
sediment, temperature, chemical composition and acidity, dilution from
seepage and tributaries and sensitivity of the aquatic community.
Stream depth within a project determines the concentration in water of
any broadcast application that falls into the water directly. One pound of
chemical per acre produces a maximum concentration of 0.367 mg/1 in water
one foot deep. The same rate of application places a maximum concentration
of 0.183 mg/1 in water two feet deep, but 1.468 mg/1 in water three inches
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deep. Interception by plant cover can prevent much of this material from
reaching the water surface.
Stream bottom character plays a role in two important and unrelated
ways. The bottom is an important site for adsorption of chemicals; bottom
configuration also affects turbulence and velocity. Stream bottoms vary
considerably in roughness and surface area per unit of volume flow. If
principles developed for soil are valid for stream bottoms (Bailey and White,
1964-), streams with rough bottom areas have a greater potential for tying up
pesticides in solution than do those with smooth bottoms. In particular,
surfaces coated with organic matter have very great adsorptive capacity.
Streams with very rough bottoms, high turbulence and large amounts of organ-
ic surface have the maximum capacity for reducing concentrations of chemi-
cals in water passing through. This condition is commonplace in streams
draining western and northern forests, in particular.
The process of adsorption has the important function of reducing total
chemical in solution, hence peak concentrations, as a load of contaminant
moves downstream. This process shortens the interval during which concen-
trations are likely to remain within a harmful range. The process of ad-
sorption is reversible, however, and adsorbed materials remain in an equil-
ibrium concentration between surface and solvent. During periods of high
concentration, material is taken out of solution, but during periods of low
concentration, it is slowly released. Some chemicals, such as amitrole,
are complexed irreversibly, and do not reappear (Bailey and White, 1964;
Norris et_ al., 1966).
Stream velocity influences both the opportunity for adsorption of a
chemical within a given reach of stream and the duration of exposure of
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organisms within that reach to potential harmful levels of pollution. Ad-
sorption is a time-dependent process. Equilibration between a solution
and a surface occurs over an extended period, during which a change in the
concentration of chemical in water can result in a change in rate of
adsorption. A decrease in solution strength to very low levels may result
in desorption. The rate of desorption has not been reported as sufficient
to maintain a detectable quantity of several pesticides during the period
after the initial contamination peak has passed (Norris, 1968).
Flow velocity plays a major role in the rate and manner in which a
pulse of contamination passes through an aquatic system. Fast-moving
streams with smooth bottoms move a concentration peak downstream rapidly
without rapid mixing of contaminated and uncontaminated water. Concentra-
tion peaks can remain near maximum for some distance downstream. The effect
of this pattern is to sustain the levels at which harm can occur, but to
confine exposures to short intervals. Fast-moving streams with substantial
roughness and high ratio of volume in pools to volume in riffles, however,
attenuate peaks rapidly. This type of stream prolongs the period during
which chemical can be detected, but reduces the period during which harmful
concentrations are present in any part of the stream system except in the
zone of entry. Spreading out the concentration peak gives a maximum oppor-
tunity for degradation mechamisms to function at subthreshold contamination
levels. Ponded water, however, may show elevated concentrations for extended
periods even with chemicals that are normally degraded rapidly. Malathion
has been found to persist at toxic levels in a pond for 1-4 days (Mount and
Stephan, 1967), and Norris (1967 ) observed phenoxy herbicides to be unusually
persistent in slow or stagnant water. Mount and Stephan, however, observed
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that the relatively more toxic butoxy ethanol ester of 2,4-D was quickly
hydrolyzed to the acid under these conditions, and hazard was considerably
reduced even though the acid remained detectable. It appears that toxic
hazard is usually inversely affected by stream velocity, but that chemical
transformation can decrease hazard even in slow water.
Biodegradation of pesticidal chemicals generally entails metabolism
by many classes of organisms. Metabolism is influenced by both temperature,
chemistry and aeration of water. The literature is weak regarding "the
principles of pesticide degradation in fresh water, and some of these ef-
fects will have to be postulated from voluminous data gathered in other
systems.
Bailey and White (1964) reviewed a substantial body of soils data which
indicated that adsorption is favored by low temperatures and by oil soluble
formulations. These conditions also suggest low rates of metabolic activity
and inaccessibility of pesticide to micro-organisms. These combinations of
conditions favoring adsorption do not appear to stimulate rapid degradation,
but do decrease the availability of chemical for producing harmful effects
in water. Muirhead-Thomson1s summary (l97l) indicates that pesticides other
than chlorinated hydrocarbons are least likely to produce toxic effects on
fish at low temperature. Increasing temperature would tend to desorb the
chemical and increase microbial activity in the presence of adequate oxy-
gen and an energy source. Throughout the normal range of temperature,
mechanisms of either physical or biological nature remove chemicals from
solutions, but toxic hazard would appear to be least in cold-water streams.
The general importance of temperature in degradation of chemicals is a
rate-related function. Those pesticides degraded slowly may be influenced
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proportionately by temperature as much as those broken down more rapidly,
but the net effect in the stream system differs. Fast-degrading chemicals,
such as the organophosphates, may degrade to an important degree during the
short interval that an elevated concentration peak passes a given point. In
slow-moving water, particularly, such degradation can make an important
difference in the distance the peak moves before its amplitude is reduced
below threshold levels of harmful effect; temperature effects may affect lo-
cal hazard. A slowly degraded chemical, conversely, such as picloram, will
not be degraded appreciably in the hours or perhaps days needed to move the
chemical out of the stream system unless it is photodegraded.
Acidity has been known to affect transformation of pesticides to more
toxic metabolites. For a classic example, the reader is referred to the
transformation of trichlorfon to dichlorvos in alkaline (pH > 7.0) water in
Chapter 4.
Availability of oxygen is generally regarded as an important prerequi-
site for energy-demanding microbial degradation of organic compounds. Aero-
bic conditions are not necessarily a requirement for breakdown, however.
Blackman et_ajU (1974) reported that phenoxy herbicides and picloram ap-
plied to flooded rice paddies at 26 pounds and 1 1/2 pounds per acre (29 kg
and 1.7 kg/ha) respectively were sufficiently degraded in six weeks to grow
an excellent crop of rice. Similar rates of degradation were observed on
upland tropical soils, as measured by several crop species, and in forest
soils. Apparently these pesticides can be broken down independently of level
of aeration, but their report indicates general rates of breakdown under warm
tropical conditions four to 12 times as rapid as reported by Norris (1970, 1971)
under temperate conditions, again emphasizing the importance of temperature.
138
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Suspended sediment provides an adsorption surface that is dispersed
through the contaminated water. Although generally regarded as undesirable
in over-all terms of water quality, the presence of an adsorption sink can
reduce the availability of a pesticide in water or in soil. Peterson's
studies with atrazine (1976) indicated that a bioassay indicator of the
chemical in nutrient solution would produce a response at one-sixteenth the
concentration of atrazine needed to produce the same response in the pre-
sence of soil. According to Bailey and White, (1964) the adsorptive capa-
cities of various materials rank organic material as having very high capa-
city, followed in decreasing order by particles with decreasing surface
charge properties, i.e., vermiculite, montromillonite, illite, chlorite,
kaolinite and oxides and hydroxides.
In summary, environmental conditions within streams can have a major
effect on duration and intensity of toxic hazard from a given contamination
of water by a chemical. These may be summarized as in Table 4.
Effects of Operational Measures to Reduce Pollution
ROLE OF BUFFER STRIPS IN REDUCING POLLUTION
Earlier in this chapter we discussed several methods of reducing pollu-
tion during application of silvicultural chemicals. As of 1976, the only
procedure required by law involves the physical isolation of treatments from
open water, i.e., the use of streamside buffer strips. Forest Practices
Acts in the states of Oregon, Washington and California contain rules relat-
ing to the application of chemicals by aircraft. The rules are the same
for all chemicals. Specifically, the Oregon rules require that a buffer
strip of one swath width be left untreated adjacent to Class I streams, i.e.,
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Table 4. Stream factors affecting the duration and intensity
of toxic hazard resulting from a pesticide contami-
nation.
Factors Affecting
Duration Maximum Intensity
Ratio of pool to riffle volume Stream velocity in the area
(rapid flow decreases concentration
Stream bottom roughness (rough if application period is prolonged)
decreases)
Depth of input water where applied
Temperature (high decreases) (deep decreases)
Adsorptive capacity of "bottom Riparian cover in project
(high exchange capacity decreases) (interception decreases)
Stream velocity (high decreases)
Organic matter in stream (high
decreases)
Riparian cover below project
(open, shallow streams subject to
photodegradation)
those large enough to support runs of anadromous fish or valuable for
domestic use (Oregon, State of, 1972). Enforcement of this rule went into
effect after considerable experience had been gained in water quality moni-
toring without regulation.
There are some data that bear on the effectiveness of buffer strips.
Comparative research results relating to buffered versus unbuffered stream-
side applications are lacking, and direct comparisons have not been pub-
lished elsewhere. The data base is far from precise, but there has been
considerable opportunity to observe relative concentrations of herbicides
in water in analogous spray operations before and after the Oregon Forest
Practices Act was implemented.
Herbicide applications in western Oregon prior to 1972 resulted in
highly variable concentrations in water. As a rough rule of thumb, maximum
concentrations of phenoxy herbicides observed in stream water were somewhat
140
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below 0.001 mg/1 per kilogram of herbicide applied per hectare for each
percentage of watershed treated. Watersheds treated entirely with two
pounds per acre of 2,4,5-T, (2.2 kg/ha) active ingredient basis, would be
expected to show less than 0.2 mg/1 2,4,5-T in water at the point of maxi-
mum contamination by this formula. This rule of thumb may not apply di-
rectly in flat forested areas with low stream velocity. Such areas tend to
have deeper streams, hence higher dilution rate. There may be a higher
ratio of open water surface to land area, however, leading to greater total
pesticide input. Data are not available for validation. Concentrations of
phenoxys as high as this were never observed with the treatment of entire
watersheds, however. The single instance of substantial underestimate by
this rule of thumb was associated with a "worst case" example. Treatment of
a narrow riparian salmonberry brush problem utilized amitrole on a long
straight segment of stream in the Oregon Coast Range. The aircraft made
repeated passes along the stream in the bottom of a deep canyon, the stream
was at low flow stage in July, and the water was only a few inches deep and
moving slowly. The resulting maximum concentration of amitrole after a
nominal rate of application of 2 pounds active ingredient per acre was 0.8
mg/1; one mile downstream it was briefly detectable at 0.008 mg/1 (Norris
et_ al_., 1965). Obviously, the concentration of spray in the immediate vici-
nity of the creek had the effect of focusing the contamination. Norris and
Moore, (1970) reported concentrations of picloram and 2,4-D in a puddle
under a power line. They found concentrations of 0.8 mg/1 2,4-D and over
0.1 mg/1 picloram more than a month after application. The chemicals had
been applied as water-soluble amine salts, six and one and one-half pounds
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active ingredient per acre (6.6 and 1.7 kg/ha), respectively. Obviously, a
crude rule of thumb as given must be qualified by the layout of the project.
Monitoring results after applications reported since implementation
of buffer strip rules have shown a reduction of herbicide peak concentra-
tions. The degree of reduction from the one-swath rule is difficult to as-
certain because of variation in rules among land managing agencies. The
Siuslaw National Forest, U.S. Forest Service, observes a swath width of 100
feet along each side of Class I streams to comply with the Oregon Forest
Practices Act. Using data from Gravelle (Figure 6) a deposit of less than
2 percent of that of a direct overflight would be expected with a high
volume helicopter application of herbicide. Data from stream monitoring
prior to initiation of this procedure can be compared to those gathered
later in a more or less direct comparison. In general, the range of con-
centrations since implementation of buffer strips has been reduced to peak
levels between one-third and one-half the former concentrations. Feeder
stream concentrations pre-1972 seldom exceeded 0.05 mg/lj post-1972 concen-
trations have seldom exceeded .02 mg/1 (L. A. Norris, 1976, personal com-
munication). In view of Gravelle's findings, it is likely that the lower-
than-expected control of pollution is attributable to the difficulty of
maintaining an even 100 foot strip along an irregular creek.
EFFECT OF APPLICATION METHOD
The effectiveness of buffer strips in minimizing pollution is dependent
on the droplet sizes being applied adjacent to the strip, basic swath width
and degree of precision in control of the aircraft. As discussed earlier,
movement of the spray across the buffer strip is inversely related to
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droplet size. Measures to eliminate fine droplets increase the effective-
ness of a given isolation. Several of these are capable of minimizing
droplets less than the 250 microns identified by Gravelle's data as the
maximimi size capable of major movement in a 1-10 mph wind. This approach
is probably restricted to herbicides because of the low feasibility of re-
ducing coverage of insecticides.
Aircraft guidance along irregular waterways renders difficult the ob-
servance of precise buffers. Fixed-wing aircraft are less able to maneuver
than helicopters and larger aircraft are less maneuverable than small craft.
Larger aircraft also apply wider swaths, presumably with proportionally
wide deposits of droplets beyond the effective swath margins. There is
therefore incentive for avoiding large fixed-wing aircraft applications near
waterways, and for using helicopters where possible adjacent to any buffer
zone. Even with helicopters, maneuvering along a crooked watercourse can
increase contamination. Turns away from a creek cause helicopter rotor
wash to direct an air blast containing spray toward the creek. Buffer
strips along a meandering stream thus need to be wide enough to preserve
the nominal protection distance with a minimum of sharp turning.
Guidance of the aircraft in relation to buffer strips has traditionally
been up to the pilot. It is not practically possible to mark edges of buf-
fer zones on the ground continuously except in certain circumstances. The
one instance in which this is feasible is that of foliage herbicide applica-
tion to a hardwood forest or brushfield. The boundary can be marked by
injecting trees along the edge of the buffer zone with herbicide so as to
create a line of defoliating trees visible from the air. Various devices
have been described for intermittent marking of spray unit boundaries under
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more general circumstances (Maksymiuk, 1975). At least one electronics man-
ufacturer (Motorola) has designed a precision guidance system for aircraft
that permits adherance to a ground-controlled vector within one meter.
Although this is interesting for maintaining accurate swath placement in
the general application, it is probably not adapted to irregular edges.
SOURCES OF TROUBLE
Examination of the "worst cases" relating to the above amitrole inci-
dent, and application to slow-moving or still water with no cover, permits
some tentative conclusions about procedures associated with potentially
serious contamination. Every instance of concentration that exceeded the
general rule of thumb was observed where shallow, slow-moving water was
treated directly, and perhaps repeatedly, within an extended stretch of
stream or pond. Even these instances have produced contamination levels be-
low concentrations shown to have caused mortality among the most sensitive
aquatic fauna (see Appendix, Table l). Under unusual circumstances, Picloram
concentrations in irrigation water could be harmful to certain crops regard-
less of a one-swath buffer, depending on crop and distance downstream to
irrigation intake. Comparable contamination by numerous of the insecticides
would cause severe damage (see Appendix).
Insecticides have not been studied in relation to specific effects of
buffer strips. Kerswill's report of New Brunswick operations (1967) in-
dicated that the size of aircraft used for application influenced the degree
to which open water could be avoided. He reported substantial fish kills in
the Miramichi River when open water was included in DDT spray patterns.
Mortality of fish began when large aircraft replaced smaller Stearman craft
1-44
-------
that had been spraying smaller blocks laid out in irregular patterns to
conform with landform. This report did not specify the width of buffer
that was used with the Stearman aircraft, but did substantiate the impor-
tance of not applying DDT to open water. He also reported that damage to
the fishery ceased altogether when phosphamidon was substituted for DDT,
again without specifying the pattern in which the phosphamidon was applied.
Reported levels of 0.1 rng/1 phosphamidon in water suggests that no buffer
strips were used, and indeed that water could not have been excluded from
direct application.
The general substitution of selective, non-persistent and non-accumulat-
ing insecticides for chlorinated hydrocarbons has reduced fish mortality.
Muirhead-Thornson (1971) indicated that mexacarbate, fenitrothion, malathion
and phosphamidon all were much less toxic to fish than DDT, and were short-
lived. Kerswill (1966, as reviewed by Muirhead-Thomson, 1971) observed that
Atlantic salmon demonstrated a one-hour lethal threshold concentration of
220 mg/1, phosphamidon, more than 2,000 times as high as the 0.1 mg/1 nor-
mally observed as maximum in aerial spray operations, with complete recovery.
Kerswill (1967) also reported that the application of two half-rate treat-
ments of DDT produced the same degree of injury to fish as a single full
dosage. Elson and Kerswill, (1966) reported little effect on fish when a
combination of DDT and phosphamidon was used, with phosphamidon being used
at one-half pound per acre within buffer strips along streams. Thus, there
is evidence that buffer strips can be treated without injury to sensitive
fisheries, but they should not be treated with chlorinated hydrocarbons.
The role of biological insect control agents for this purpose has not been
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elucidated with respect to water quality, "but should be safe in the conven-
tional sense.
RESOURCE COSTS IN POLLUTION CONTROL
Even if using buffer strips illustrates a clear and reasonable pattern
in modifying concentrations of toxic substances in streamflow, buffer strips
also may have an effect, sometimes adverse, on the non-aquatic resources.
The acreage included in buffer zones tends to be lower slopes, with deep
soils having favorable water regimes. Buffer zones 100 feet wide require
25 acres per mile of stream. The typically favorable site quality of these
acres for timber suggests that timber resource productivity within these
zones is proportionately higher than the relative area of land surface in-
cluded in the buffer strips.
Productivity within buffer strips may or may not be compromised by lack
of treatment, depending on the nature of the problem and proposed treatment.
Buffer strips left in areas treated for site preparation with herbicides
remain largely out of timber production if they are in a non-productive
state initially. They remain productive as big game habitat, possibly at a.
level inferior to the areas sprayed with phenoxy herbicides, if cover is
above browse height. In a recent report, Newton (1976) has described re-
search with the shade tolerant western hemlock indicating that successful
reforestation with such species is possible with minimum site preparation.
This report does conclude, however, that heavy overhead competition limits
success, and this method is principally a means for reducing intensity of
herbicide use, rather than eliminating all use. Areas excluded from release
herbicide sprays are likely to sustain heavy losses of growth from rapidly
146 '
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encroaching alder and salmonberry in coastal areas of the Pacific Northwest.
Losses can be measured in terms of lost investment in plantations or in
unrealized stumpage revenue in the future. The extent of losses has not
been calculated precisely. Release sprays are not normally scheduled un-
less suppression is imminent or already present. On such areas, it is es-
timated that loss can amount to 25-100 percent of a plantation with 1976
potential value of $200-1,000 per acre. The total value and proportion of
value lost are generally lower elsewhere in the United States. Crude esti-
mates can be made on the basis of potential productivity. Where there is
clear evidence of adverse effects of buffer strips and no observable gains
in condition of aquatic systems resulting from their use, the merits of buf-
fers are open to question.
Effects of buffer strips on insect populations remain conjectural.
Observations made during the 197-4 outbreak of Douglas-fir tussock moth in-
dicated that populations were commonly decreasing at the time DDT was applied,
and the 200-foot-wide buffer strips did not carry high surviving populations.
Moreover, streamside habitats do not normally carry the heaviest populations.
An insect species with less dramatic population fluctuations and with females
which travel considerable distances, e.g. the eastern spruce budworm, could
reinfest sprayed areas from buffer strips. There are thus apparently areas
where buffers are useful and consistent with insect management regimes, but
there may be exceptions. In view of the potential risk of injury to aquatic
systems from insecticides, however, any decision to abandon buffers carries
considerable risk of contamination by these materials.
Non-herbicidal programs in vegetation management are in widespread use.
They are sometimes recommended as means of reducing environmental impact.
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Hand felling of brush and hardwoods, and mechanical scarification are the
most common. Of these, hand felling presumably has no direct effect on
water quality, but scarification can have serious repercussions. Froehlich
(197/4) observed that there are only limited periods when machine use does
not result in serious compaction and loss of infiltration capacity on some
forest soils. Steep topography aggravates the runoff problem, and many
agencies do not scarify on slopes greater than 30 percent. Resulting run-
off after devegetation causes soil losses and siltation problems even on
gentle topography. Reports of soil loss and siltation are legion in rela-
tion to agricultural operations. Dissmeyer (1973) reported that soil
losses in the southeastern forest region were severe following site prepa-
ration methods that expose and disturb soil in areas of high-intensity
precipitation. Methods that do not disturb the soil apparently are asso-
ciated with water quality similar to that from undisturbed forests. Thus,
it is clear that the substitution of mechanical methods for herbicides re-
duces the concentration of herbicide in water, but tends to increase the
silt load and turbidity substantially. Successful hand-cutting methods
prevent both siltation and herbicide contamination. Subsequent herbicide
treatment is often required to achieve adequate control of sprouting spe-
cies, however.
Aerial application of endrin-treated conifer seed invariably deposits
some endrin in creeks. Amounts are extremely small, and endrin is not
known to have had measurable impact on stream biota, despite the occasional
occurrence of detectable quantities in water (Moore et_ a^., 1974). The
effect of endrin in forest streams has not been investigated in detail,
however, and the assumption of negligible effect is an extrapolation of
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laboratory data. Substitute practices include the choices of applying un-
treated seed or hand planting. Both choices eliminate the addition of
endrin to water. The use of untreated seed generally results in seeding
failure (Bever, 1953), whereas hand planting increases success in reforesta-
tion considerably. The latter pattern is so well established that hand
planting has supplanted aerial seeding for most reforestation efforts, des-
pite its higher cost.
Indirect methods of wildlife damage control include the use of herbi-
cides in habitat management. Borrecco (1973) reported successful management
of small mammal populations on an experimental basis by controlling certain
species of plants with herbicides. Vegetation control had the simultaneous
effects of reducing animal predation on seedlings and reducing vegetative
competition to seedlings. Cost of such use of herb control is greater than
for endrin treatment, and the practice is normally used in conjunction with
planting rather than seeding. The benefits of such weed control in planta-
tion establishment are substantial (Newton, 1970). The herbicides used to
this end are used at application rates roughly 500 times as great as those
of endrin, but with less toxic hazard.
Proposals have been made for the development of management systems in-
volving generally low impact, but preserving the advantages of chemicals.
Newton has proposed (1975 letter to Oregon State Forestry Department) that
Oregon Forest Practice rules permit the application of herbicides within
buffer zones when forestry-registered materials are available that control
streamside species, and are also registered for stream and ditclibank con-
trol. The herbicide ammonium ethyl carbamoyl phosphonate has such registra-
tion status, and is particularly effective on salmonberry and vine maple in
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the Pacific Northwest. This practice could likely have an impact on stream-
side vegetation and its ability to shade the stream channel. The applica-
tion of this approach can properly be decided on the basis of debris and
temperature criteria in the absence of toxic hazard. Ammonium ethyl car-
bamoyl phosphonate is not applied in oil.
Siltation resulting from chronic suppression of vegetation in Christmas
tree plantations can be slowed by vegetation management programs involving
herbicides. Newton proposed to the Northwest Christmas Tree Growers Associa-
tion (197/4 letter) that a program be developed in which short residue her-
bicides be used in conjunction with the use of grass or nitrogen-fixing
legume cover crops. There is ample research and operational data suggesting
that such practices are highly effective, but the appropriate herbicides
have not been registered for this purpose.
Soil fertilization practices, except for those involving Christmas
tree production, have traditionally relied on aerial application. Urea
nitrogen fertilizers are applied as prilled products that distribute uniform-
ly. Buffer zones along creeks can be narrow without substantial application
to open water. Phosphate applications have utilized a considerable amount
of rock phosphate, applied as a dust. This material can move in atmospheric
drift in patterns less controllable than those obtained with prills. Dr.
Pritchett, of the University of Florida at Gainsville (personal communication,
1976) has indicated that rock phosphate dust undoubtedly can settle in open
water during aerial fertilization operations. He has observed, however,
that phosphate concentrations are characteristically low in the southern
Coastal Plain and Flatwoods area. It is likely that application with ground
equipment at the time of planting would reduce losses to even lower levels,
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while enhancing availability to planted seedlings. Partly acidulated and
prilled ground rock phosphate has "been developed by TVA. When available,
its use will reduce drift during application.
A relatively recent development in forest fertilization experimenta-
tion has been spraying liquid urea-ammonium nitrate solution directly on
foliage. Since this approach does not attempt to add chemicals to forest
soils, the probability of loss to streams should be minimal. Preliminary
results indicate that stream contamination due to foliar fertilization is
less than from conventional urea application, as pellets. Since foliar
rates of application have been somewhat lighter (150#/acre of N), smaller
fertilizer losses may be attributable to that factor (unpublished BIM
report, Roseburg, OR, 1975, R. Miller and S. Wert). Increased wood pro-
duction per unit of nitrogen added presently favors the foliar procedure.
If fertilizer costs continue to rise, this method may be more commonly
used in the future, especially when means are developed to avoid the foliar
damage which can occur at present rates of application.
The general impacts of the silvicultural chemical practices as cur-
rently applied without buffer zones are summarized in Table 5. Several
non-chemical practices are listed for purposes of comparison.
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Tabl6 5. Summary of effects of aerial application of chemicals and alternative silvicultural
practices on water quality.
Practice
Fertilization
Forest Site Preparation
Chemical
ro
Chemical Used
Urea
Phosphorus
Amitrole
Ammonium ethyl
carbamoyl
phosphonate
Atrazine/Simazine
Dalapon
Picloram
Pollutant Pattern
Brief elevation of urea and
low-level ammonium concen-
trations. Slight later ele-
vation of nitrate.
Brief elevation of phosphate
concentration.
Spike concentration*.
Spike concentration*, followed
by very slight contamination
in runoff or seepage.
Duration of
Measurable Pollution
Urea limited to immed-
iately after applica-
tion. Some elevation
of nitrate from first
fall rains after dry
summer.
Limited to flooding
runoff period.
1-7 days.
Spike is brief. Seep-
age may continue sev-
eral months in range
< 5 ppb.
Group Most Likely
to be Affected by
Pollution if Any
None known. Low
possibility of
injury to fish
from NHj in warm
water of high pH.
None known.
None known.
Irrigation water
users (potatoes,
tobacco, legumes).
-------
Table 5. ( continued)
Practice
Non-Chemical
Scarification:
Steep > 30% slope
Flat < 5?5 slope
Scarification &
Chemical
Fire
Chemical Used
Phenoxys
None
Gentle 5-30$ slope None
None
2,4,5-T
Atrazine
None
Pollutant Pattern
Spike concentration*.
Turbidity with storms; mass
soil failures.
Turbidity with storms. Most
serious in areas with wet
summers.
Turbidity with storms in
wet summer areas only.
Turbidity plus chemical
associated with silt.
Turbidity with storms, mild
to severe, depending on
steepness, intensity of
fire and rains.
Duration of
Measurable Pollution
1-7 days
During storm flow, as
long as soil is devege-
tated.
Storm flow only, as
long as soil is deve-
getated. Atrazine
prolongs period of
exposed soil.
Storm flow, only while
devegetated.
Group Most Likely
to be Affected by
Pollution if Any
None known.
All, some severely.
Aquatic systems,
especially spawn-
ing fish, potable
users.
Potable users.
Aquatic systems,
potable users.
None to severe on
fish spawning
beds.
-------
Table 5. (continued)
Practice
Fire Plus Chemical
Chemical Used
2,4,5-T and/or
Dinoseb
Pollutant Pattern
Mild turbidity. Spike* of
herbicide.
Duration of
Measurable Pollution
Storm flow only until
site revegetates.
Group Most Likely
to be Affected by
Pollution if Any
None to severe on
fish spawning
beds.
Insect Control
Biological
Chemical
-F-
None
Carbaryl
Diazinon
Disulfoton
Endosulfan
Fenitrothion
Not known.
Spikes* in many streams
coalesce into prolonged
river pattern of low con-
centration.
Spikes* in many streams
coalesce into prolonged
pattern of low concentra-
tion in rivers; persistent
chlorinated hydrocarbon
may appear in very low
concentrations later.
Spike* in many streams
coalesce into prolonged
river pattern of low con-
centration .
Not known.
1-7 days in feeder
streams; 1-3 days
longer in river.
Persistent. May be
problem with food
chain species for
extended period.
1-7 days in feeder
streams; 1-3 days
longer in river.
None observed.
Aquatic insects;
effects no more
than 2 weeks.
Non-cumulative.
None known.
Aquatic insects;
effects no more
than 2 weeks,
non-cumulative.
Fish extremely
sensitive. Also
aquatic insects.
Impact likely
even with buffer
strips.
Possibly aquatic
insects, low
impact unless
applied directly
to water.
-------
Table 5. (continued)
Practice
Insect Control (cont.)
Chemical Used
Guthlon
Lindane
Malathlon
Ul
vn
Rodent Control
Seed Coat
Pho sphami don
Trichlorfon
Endrin
Pollutant Pattern
Spike* in many streams
coalesce into prolonged
river pattern of low con-
centration .
Not used aerially; not
found in water.
Spikes* in many streams
coalesce into prolonged
pattern of low concentra-
tion in rivers.
Spikes* of low concentra-
tion in many streams
coalesce into prolonged
pattern of low concentra-
tion in rivers.
Brief spike*, very low
maximum.
Duration of
Measurable Pollution
1-7 days in feeder
streams; 1-3 days
longer in river.
None
1-7 days in feeder
streams; 1-3 days
longer in rivers.
Persistent, but
levels too low for
toxic hazard.
Group Most Likely
to be Affected by '
Pollution if Any
Aquatic insects
very sensitive -
impact likely,
but brief even
with narrow buffer
strips.
None
Aquatic insects
very sensitive,
some impact
likely, but brief,
without buffer
strips.
Aquatic insects if
water sprayed
directly.
None known.
-------
T&ble 5. (continued)
Practice
Chemical Used
Pollutant Pattern
Herbicide
Triazines, 2,4-D Brief spike*.
Dalapon
Duration of
Measurable Pollution
1-7 days.
Group Most Likely
to be Affected by
Pollution if Any
None known.
* "Spike" concentrations are defined as those which diminish to less than ten percent of maximum within 48 hours.
-------
CHAPTER6
POLLUTION CONTROL
GUIDEU
-------
-------
POLLUTION CONTROL GUIDELINES
The pollution control strategy outlined in this document is directed
primarily toward maintenance of forest water quality. A secondary goal is
preservation of flexibility in achieving silyicultural objectives within
those goals. Development of pollution control strategy has thus far empha-
sized determination of practices having the most potential for harming
water quality and review of procedures minimizing adverse effects. This
analysis has included a broad array of silvicultural practices, many of
which are applied throughout the United States.
Silvicultural practices have been analyzed for their impacts on water
quality from the standpoints of chemical entry into aquatic ecosystems or
water used for drmking or irrigation. Chemical concentrations in water
have been proposed at which significant harm is not likely to befall either
aquatic ecosystem structure or productivity. Especially stringent criteria
have been developed where unusually sensitive aquatic species or user groups
have been identified. Larger margins of safety have been developed for major
river systems than for smaller streams. Alternative practices have been
evaluated both from the standpoint of water quality and effectiveness in
reaching silvicultural objectives. Non-chemical water quality impacts have
been included in a comparison of alternatives.
Water pollution from use of chemicals in forestry is not a widespread
problem. Levels of pollution that cause measurable harm to water users or
aquatic ecosystems occur infrequently. Problems that do exist are restricted
to the persistent herbicide, picloram, and to the use of insecticides on large
areas. At present, virtually all aerially applied herbicides and fertilizers
are used under the supervision of professional foresters and technical
157
-------
specialists who are aware of the chief potential hazards of misuse. Quality
control is generally good in field operations, and water monitoring has re-
flected a lack of accidents involving spills in watercourses. The poten-
tially more hazardous insecticide applications are usually coordinated
public-private operations with considerable prior organization and review.
These use patterns are apparently consistent with maintenance of forest
watershed quality goals. The exceptions are the principal targets for ad-
ditional controls.
Priorities for Pollution Control
The goal of eliminating serious water quality impacts from the use of
forest chemicals has largely been achieved by restricting the general use of
organochlorine insecticides, and by avoiding direct application of insect-
icides to open water. There is some remaining hazard to aquatic insects
and other food species from the more toxic of the organophosphate insect-
icides, and from the remaining occasional use of endosulfan. Even though
their use has not had major obvious effects on fish, the scale of operations
suggests that reduction of their potential for injuring aquatic systems
with insecticides should receive the highest priority. Principal needs are
adequate buffer strips and special application techniques near the water.
Second priority is given to the maintenance of productivity in stream-
side buffer strips, and in many other areas, by means other than
mechanical vegetation control. Herbicides are available that are effective
and safe in these areas. Their use can maintain productivity without caus-
ing siltation or other problems relating to soil damage. Presently regis-
tered materials can be used effectively to the water's edge, and others in
158
-------
developmental stages can be used with negligible impact on water quality
with comparable or greater effectiveness in competition control. Procedures
for establishing stands of conifers in residual brush cover need to be
developed so that less intensive vegetation control is needed. Part of
this task is the development of improved application precision. The re-
moval of buffer strips from the productive forest land base is a land use
question that can be considered independently of pollution only in the
presence of non-polluting technology.
Third priority is given to the training and licensing of applicators
so as to minimize direct contamination from ground equipment and aerial
applicator ground crews. Particular attention is needed for avoidance of
spills, dumping of wash water and back siphoning from spray tanks.
Fourth priority is given to the problem of picloram and dicamba residues
in water used for irrigation. This is principally a physical placement
problem in relation to both proximity to water, and stream distance between
herbicide projects and irrigation users with sensitive crops. This priority
is given in anticipation of future problems.
As a general silvicultural goal, there needs to be development of
management systems that prevent the occurrence of the problems on which
pesticidal chemicals are normally used. Progress toward that end could
reduce future need to rely on chemical expedients. Epidemic levels of
pests, both animal and plant, are often outgrowths of management that
failed to include adequate consideration for pest prevention. Little can
be done about past errors, but future silvicultural operations can prevent
development of many problems on the scale at which they now occur. This
goal is inextricably intertwined with the direct pollution control priorities.
159
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RulesforApplicatk»ofa»eiBicaIsinSflviculture
Table 6 provides a list of forest management practices involving the
application of chemicals, and outlines the rules for buffer strip treatment
and monitoring so as to meet the goals of this program. Methods used to
reduce impact of chemicals (Priority I) include designation of buffer zones
of widths in accordance with the potential hazard posed by the chemical.
The rationale behind recommendations for buffer strip widths is based on
the earlier described 20-fold decrease of contamination with each herbicide
swath width away from the stream and a five-fold decrease per swath of low-
volume insecticides with winds less than 5 mph. Based on experience with
various pesticides, the proposed criteria for water concentrations (Chapter
4, Table 3) will be met with a margin of safety when registered rates of
application are applied as recommended. In those exceptions where buffer
strips are defined in terms of absolute width, the problem is the physical
movement overland or through the soil in subsurface flow, a group of pro-
cesses not affected by application technology.
To achieve the second priority, meeting forest production goals without
compromising water quality, emphasis is given to the identification of prac-
tices that have adverse impacts near water, and substituting less harmful
practices. Exceptional conditions under which untreated buffer zones are
recommended are identified so that unnecessary loss of productivity can be
avoided.
160
-------
Monitoring
Monitoring will be needed to insure that the recommendations are a)
being observed, and b) effective in maintaining water quality. Monitoring
responsibility for validation of practices will be the responsibility of
state and federal water resources agencies, and operational quality
control will be the responsibility of the operator. Monitoring by users
will be necessary on a limited scale to provide a record of the consequence
of the chemical activity at the point of maximum potential trouble. The
intensity of monitoring is specified in Table 6. Specific treatment of
samples is outlined in procedures compiled by Freed et al. (1971), of which
a portion germane to water is reproduced below:
Sampling Points
Selection of an appropriate sampling station is important
since the value of the information obtained is only as good as
the sample collected. The sample should be representative of
the volume of water passing the sampling point, and it should
be possible to collect a sample without stirring up bottom
sediments or kicking surface debris into the stream. When
the treatment unit lies adjacent to the stream to be sampled,
the sampling point must be downstream of all small side chan-
nels flowing from the treated area. At the same time, however,
we want to sample the stream as close to the lower boundary as
possible so that the samples will represent the maximum con-
centration of chemicals to which aquatic organisms may have
been exposed.
Control samples are normally collected at the same samp-
ling station prior to spraying, but in some situations it will
be possible to obtain these samples upstream from the spray
unit. In either case, the sampling point should not be subject
to contamination by aerial drift during the sampling period.
In critical situations such as spraying brush above a water
intake for a fish hatchery or water supply, sampling stations
should be established near the intake.
Collection of Samples
Before the project is begun, appropriate sample containers
must be obtained. The type and size of sample, the container
161
-------
and conditions for storage and transport should be verified with
the analytical laboratory. If herbicides like 2,4-D, 2,4,5-T or
picloram, are used, samples should be taken in glass containers
and treated with sodium hydroxide (NaOH) to prevent loss of any
herbicide residue that may be present. Amitrole is highly sol-
uble in water and stable so treatment with sodium hydroxide is
not needed. It should be collected in glass containers. For
fertilizer, more intensive background sampling is required and
the sample containers and mode of preservation differ. It is
essential to check with an analytical laboratory or the chemist
who will do the analysis to determine container and preservation
requirements. Samples should be representative of the total
volume of water flowing past the collection point. For small
streams, collect a grab sample at the lower end of a straight,
narrow length of channel carrying a steady flow of water. On
larger streams, the samples should be taken near the center of
the channel at a depth of 2-4 inches. The individual collecting
the samples must not have any herbicides or other contaminants on
his hands or clothing and the sample containers must also be free
of contamination. These precautions are extremely critical be-
cause of the sensitivity of analytical methods. As a general pre-
caution the person collecting the samples should not have any
other contact with an active spray project.
Each sample must be clearly identified and all pertinent
information correctly and completely recorded on a tag or label
securely attached to the container. In addition to assigning an
identifying number, the attached tag or label should show the
date and time collected, location, weather conditions since time
of application, and name of collector. Other information that
may be recorded is the rate of application, chemical formulation
used and size of area treated.
Timing of Collection
The number of samples collected and the timing, or sampling
interval, will depend in part on the particular project being
monitored. Following is an example of the sampling sequence
that might be used for a chemical brush control project which is
not near a highly sensitive area.
Hours after spraying is begun:
1. Control (prespray)
2. 15 minutes to 1 hour
3. 3 hours
4. 24 hours
5. 48 hours
6. 72 hours
162
-------
Timing of the collection of sample number 2 depends on the
distance between the lower unit boundary and the sampling point.
If this point is immediately below the unit, sample 2 should be
taken within 15 minutes after spraying is started. If the
sampling point is downstream some distance below the unit, col-
lection of sample 2 can be delayed. This timing also applies
when the unit is sprayed in late evening to take advantage of
good weather conditions. Sample 2 should be taken at the time
interval indicated and sample 3 can be delayed until the next
morning. In this case, samples 4, 5, and 6 would still be
taken at 24-hour intervals from the time spraying started. The
guiding principle is to collect samples when you expect resi-
dues to pass the sampling point.
Due to poor weather, equipment failure, or the size of the
area, it is often necessary to spray a unit over a period of
several days. Should this occur during a monitoring program,
samples 2 and 3 should be taken each day that spray is applied.
Samples 4, 5, and 6 then would be taken at 24-hour intervals
after the last application on the unit. When the treatment
unit lies within a municipal watershed or in a watershed that
supplies a fish hatchery, additional samples should be taken 5
to 10 days after application. Following rain and wind, any
time within the first 3 to 4 weeks after application may require
the collection of additional water samples. Many chemicals
tend to be tightly held in the forest floor and soil, but it is
possible that residues along the stream may move into the stream
channel by subsurface or overland flow. At least one sample
should be taken during and after the period of peak flow.
Transport and Storage
Sample containers, whether empty or full, should not be
transported or stored with chemicals. As soon as sampling
has been completed, the accumulated samples should be shipped
to the laboratory for chemical analysis. If for some reason
the samples are not analyzed immediately, storage conditions
should be verified with the analytical laboratory.
Chemical analysis for pesticide residues is an expensive
proposition because of the time and equipment required. It
may be desirable to reduce the cost of monitoring on some
projects by compositing some of the samples and thereby re-
ducing the number of analyses required. This can be done by
combining equal parts of each of several samples taken at a
monitoring point, excluding the control sample. No more than
4 or 5 samples should be included in a composite and the re-
mainder of each individual sample should be saved in case the
analytical results on the composite show that more detailed
information is needed. The composite sample must be so marked
and a complete identification included with it when submitted
for analysis.
163
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Safety
All pesticides and samples that may contain their residues,
are potentially poisonous and should be handled accordingly.
They are selected for their toxic properties toward a specific
target and every effort must be made to insure that nontarget
components of the environment are not adversely affected as the
result of misuse or carlessness. In the case of an accidental
spill or drop of herbicide into open streams, lakes, or other
bodies of water, all interested persons should be notified and
monitoring procedures should be started immediately.
Monitoring is an inexact procedure, and some weaknesses in present pro-
cedure need to be resolved. In particular, methods need to be developed
that distinguish between dissolved and adsorbed chemicals. Monitoring re-
commendations include filtration for some of the more strongly adsorbed
chemicals so as to determine solution levels. There is no feasible method
at present for monitoring concentrations in small aquatic organisms. Moni-
toring procedural amendments to the above general guide are given in Table 6.
Noteworthy among the deviations from Freed et al. (1971) are the frequency
of samples. Frequent samples are necessary for research toward determination
,of patterns of fluctuation of chemical concentration. Operational samples
are,feasible at lower frequency because they may be interpreted in terms of
existing research data on concentration fluctuation.
Pesticide analyses are exacting and costly. It may not be necessary to
have samples analyzed if there is no evidence of contamination. The samples
should be taken and stored under refrigeration for at least 3 months, however.
If a problem arises, samples should be analyzed by competent commercial or
government laboratories equipped for the chemicals and precision needed.
16/4
-------
Tabl6 6. Guidelines for Applying chemicals by aircraft, and water monitoring in silvicultural practices.
Practice
Chemical Used
Minimum Distance Between Nearest
Water and Center Line of
Nearest Swath
Treatment of Buffer
Fertilization Urea
Phosphorus
Forest Site Amitrole
Preparation
Ammonium ethyl
Carbomyl phosphonate
Atrazine
Dalapon
Phenoxys
3A of an effective
swath width (ESW).
3/4 ESW* Exceptions:
upstream from lake or
impoundment.
1/2 ESW* Exceptions:
within a mile of pot-
able users, 50-foot
buffer.
1/2 ESW*
1/2 ESW* Exceptions:
scarified areas, 50
feet.
1/2 ESW
1/2 ESW
Apply by ground rig.
Apply by ground rig.
a) Apply by ground rig.
b) Apply substitute chemical.
c) Plant buffer zone with
tolerant tree species.
Can be treated.
Do not disturb soil within
buffer zone.
Do not disturb soil within
50 feet of creek.
Can be treated.
Suggested
Location and Frequency
of Water Sampling
Composite, Day 1, at
potable user site, if
within 1 mile down-
stream from project.
None
Composite, Days 1 & 2,
at potable user site
if within 1 mile down-
stream.
Composite, Day 1 at
potable user site if
within 1 mile of pro-
ject downstream.
None
None
Composite, Day 1, at
intake if potable user
within 1 mile of pro-
ject downstream.
-------
Table 6. (continued)
Practice
Chemical Used
Picloram
Jfininnan Distance Between Nearest
Water and Center Line of
Nearest Swath
Forest Insect
Control
Biological
Chemical
Diazinon
Disulfoton
Treatment of Buffer
100 feet (200 feet when
applied during period of
rainfall surplus).
Can be treated with substitute
chemical within prescribed
limits.
Bacillus thuringiensis None*
Nuclear polyhedrosis None*
Carbaryl
1 ESW* or 100 feet,
whichever is greater.
Can be treated.
Can be treated.
May treat with biological
agent.
1 ESW* or 100 feet,
whichever is greater.
1 ESW* or 100 feet,
whichever is greater.
Suggested
Location and Frequency
of Water Sampling
Composite, weekly at
irrigation user if
within 5 miles of
project, and crops in-
clude potatoes, tobacco
or legumes. Sample
after spraying, again
in sequence after ef-
fective rainfall.
None
None
Composite each day of
spraying immediately
downstream from project
and above potable user,
and 2 days after. Sam-
ple at water intake, if
within 2 miles of pro-
ject. Filter samples.
-------
Table 6. (continued)
Practice
Chemical Used
Forest Insect Endosulfan
Control (cont. )
Fenitrothion
Guthion
Malathion
Phosphamidon
Rodent Control
(Seeding)
Chemical
Trichlorfon
Endrin
Minimum Distance Between Nearest
Water and Center Line of
Nearest Swath
Treatment of Buffer
4 ESW* or 300 feet,
whichever is greater.
1 ESW*
3 ESW* or 200 feet,
whichever is greater.
1 ESW* or 100 feet,
whichever is greater.
May treat with carbaryl diazi-
non, fenitrothion or phospha-
midon to 1 ESW from water.
May use biological agent.
Suggested
Location and Frequency
of Water Sampling
Sample as with organo-
phosphorus insecti-
cides, but sample also
after each heavy rain
for next month.
Same as carbaryl.
3/4 ESW
Can be treated by hand.
None
*For definition and discussion of ESW see pages 118 and 119.
Designation of "None" or 1/2 ESW under Buffer Strip Width implies only that buffer strip width is at the
discretion of the operator, and that direct impact on water quality is not at issue. Even without a buffer
strip, the aircraft should never be operated within a half-ESW of streams that are likely to have fish in them.'
at time of chemical application. For those insecticides requiring one or more effective swath widths, the pro-
posed buffers are for helicopters with droplet size of 200 u MUD. If droplets are smaller or large fixed-wing
aircraft are used, buffers should be 200 feet plus the given swath numbers. Helicopters may be used in conjunc-
tion with large aircraft.
-------
-------
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-------
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APPENDIX
-------
-------
Appendix Table I. Toxkaty Data For Sflvicuftural Chemicals
03
Mammals and Birds
Acute Oral LD$Q
ing/kg of Body Weight
Aquatic Organisms
Acute LC5n
Chemical
Fertilizer
Nitrate
Nitrite
Organism
Fish
Bluegill
Bluegill
Chinook salmon
Rainbow trout
Largemouth bass
Channel catfish
Fish
Chinook salmon
Rainbow trout
Rainbow trout,
flow thru.
NaNO- 200 96 hr
KN03-*420 96 hr
1360 96 hr
1310 96 hr
.900 mgA 96 hr
.550 mgA 2A hr
.190 mgA 96 hr
.390 mgA 96 hr
Chronic Effects No Effect Level Reference
Trama 1954
Trama 1954
West in 1974
We s tin 1974
400 Khepp & Arkin 1973
400 Knepp & Arkin 1973
Westin 1974
.150 mgA Smith & Williams 1974
48 hrs
60 mgA 10 days Russo et al. 1974
-------
Appendix Table I. (continued)
Chemical
Organism
Mammals and Birds
Acute Oral LDj,.
mg/kg of Body Weight
Aquatic Organisms
Acute
Chronic Effects No Effect Level
Reference
Herbicides
Amitrole
aminotriazole
Mammal
H1
Ammonium ethyl
carbamoyl
phosphonate
Rat
Fish
Largemouth bass
Bluegill
Coho salmon
Crustacean
Crayfish
Daphnia magna
Mammal
Rat
Guinea pig
Birds
Mallards
Bobwhite quail
1100.
100 mg/1 48 hr
32.5 mg/1 24 hr
.003 mg/1 48 hr
24,000 mg/kg
7,380 mg/kg
> 10,000 mg/kg
> 10,000 mg/kg
62.5 mg/1 14 day
Cont. flow, all survived
100. mg/1 48 hr
2,200 mg/kg/day
2 weeks
Bailey & White 1965
Bond 1960
Sanders 197C
Bond et al. 1960
Sanders 1970
Sanders 1970
Dupont Corp.
Tech. Inf.
-------
Appendix Table I. (continued)
Manuals and Birds
Acute Oral LDjo
mg/kg of Body Weight
Chemical
Organism
Aquatic Organisms
Acute LC
50-
Mg/1
Chronic Effects No Effect Level Reference
c»
o
Herbicides (cont.)
Ammonium ethyl
carbamoyl
phosphonate (cont.)
Arsenicals
Cacodylic acid
(dimethylarsinic
acid)
Fish
Fathead minnow
Bluegill
Rainbow trout
Rat (male)
Birds
Chicken
Mallard duck
Chukar
Fish
> 1,000 mg/1
670 mg/1
> 1,000 mg/1
1,400
>2,000
>2,000
100 mg/kg,
feed/d, 90d
10O mg/kg,
feed/d,lOd
us EPA 540-1-75-021
Bluegill
16. mg/1 96 hr
-------
Appendix Table I. (continued)
Chemical
Mammals and Birds
Acute Oral ID*..
mg/kg of Body Weight
Aquatic Organisms
Acute
Organism
Chronic Effects No Effect Level
Reference
CO
Herbicides (cont.)
Arsenical
Cacodylic acid
(dimethylarsinic
acid)
Monosodium
Methane
Arsonate
(MSMA.)
Marine & Estuarine
Pink shrimp
Eastern oyster
Daphnia magna
Mammals
Rat
Dog
Cow
Birds
Bobwhite quail
Fish
Fathead minnow
Bluegill
Goldfish
Channel catfish
Rainbow trout
1800.
1700.
3,300
13.3 rag/1 96 hr
49. mg/1 96 hr
31. mg/1 96 hr
27. mg/1 96 hr
96. mg/1 96 hr
40. mg/1 48 hr
1. mg/1 96 hr
.001 mg/1 32 d
100 mg/kg of
feed, 90 d.
30 mg/kg of
feed, 90 d.
US EPA-540-1-75-020
-------
Appendix Table I. (continued)
Chemical
Mammals and Birds
Acute Oral ID™
mg/kg of Body Weight
Aquatic Organisms
Acute LCc.. Mg/1
Organism
Chronic Effects Mo Effect Level Reference
CO
Herbicides (cont.)
Arsenical
Monosodium
Methane
Arsonate
Dalapon
Sodium salt
Marine & Estuarine
Scud
Pink shrimp
Eastern oyster
Mammals
Rat
Fish
Fathead minnow
Bluegill
Coho salmon
100. mg/1 96 hr
1. mg/1 48 hr
1. mg/1 48 hr
3860.
290. 96 hr
290. 96 hr
340. 96 hr
Ben-Dyke et al. 1970
Surber & Pickering 1962
Surber & Pickering 1962
Bond et al. I960
Crustaceans
Daphnia
Insects
Stonefly
11. 48 hr
100 mg/1
96 hr
Sanders & Cope 1966
Sanders & Cope 1968
-------
Appendix Table I. (continued)
Chemical
Organism
Mammals and Birds
Acute Oral LDj0
mgAg of Body Weight
Aquatic Organisms
Acute LC5n
Chronic Effects No Effect Level Reference
Herbicides (cont.)
Dicamba
(Banvel)
co.
Mammals
Rat
Mouse
Rabbit
Guinea pig
Birds
Chicken
Pheasant
Fish
Bluegill
Rainbow trout
Coho salmon juv.
Carp
Crustaceans
Scud
Daphnia
Crayfish
1040 mgAg
1190 mgAg
2000 mgAg
3000 mgAg
673 mgAg
800 mgAg
23 mg/1 96 hr
28 mg/1 96 hr
121 mg/1 48 hr
465 mg/1 48 hr
3.9 mg/1 96 hr
Bailey & White 1965
Velsicol Chem. Corp.
Bui. 521-2
Velsicol Chem. Corp.
Bui. 521-2
Sanders 1969
100. 48 hr
100. 48 hr
-------
Appendix Table I. (continued)
Chemical
Mammals and Birds
Acute Oral LDjg
of Body Weight
Aquatic Organisms
Acute LC
Organism
50-
Hg/1
Chronic Effects No Effect Level
Reference
Herbicides (cont.)
Picloram
(Tordon)
CO
Mammals
Rat
Guinea pig
Birds
Chicken
Bobwhite
Fish
Rainbow trout
Coho salmon
Bluegill
Largemouth bass
Fathead minnow
8200.
3000.
> 500 mgAg
rat, oral
50 mgAg rat (90 d)
180 mgAg sheep (90 d)
130 mgAg calf (90 d)
150 mgAg dog (2 yr)
Nat. Res.
Council
Canada
Picloram, NRCC
13684
6,000
10,000
34. mg/1
29. mg/1
26.5 mg/1
19.7 mgA
52. mg/1
V
-------
Appendix Table I. (continued)
Chemical
Herbicides (eont.)
S-Triazines
Atrazine
00
VJl
Simazine
Mammals and Birds
Acute Oral LD5o
mg/kg of Body Weight
Aquatic Organisms
Acute
Organism
Chronic Effects
No Effect Level
Reference
Mammals
Rat
Mouse
Sheep
Fish
Rainbow trout
Bluegill
Goldfish
Channel catfish
Crustacean
Daphnia magna
Mammals
Rat
Cow
Fish
Fathead minnow
Coho salmon
1750. rag/kg
1750. mg/kg
4.5 mg/1 96 hr
24. mg/1 96 hr
60. mg/1 96 hr
3.6 mg/1 48 hr
5000.
6. mgA 96 hr
6.6 mg/1 48 hr
500 mg/kg
reduce wt. gain
Bailey i White 1965
Dalgaard-Mikkelsen & Paulsen 1962
10 mg/1 96 hr
Anon. 1971
Anon. 1971
Anon. 1971
Jones 1962
750 mg/kg wt. loss
Water Quality Criteria 1968
Bailey & White 1965
Palmer & Radeleff 1969
.003 mg/1
Bond et al. I960
-------
Appendix Table I. (continued)
Mammals and Birds
Acute Oral LD5Q
ing/kg of Body Weight
Aquatic Organisms
Acute LC.;,, Mg/1
CO
Chemical
Herbicides (cont.)
S-Triazines ( cont . )
Simazine ( cont . )
Phenoxy
2,4,5-TP (Silvex)
acid
butylester
PGBE ester
PGBE ester
PGBE ester
PGBE ester
acid
Organism
Fish ( cont . )
Bluegill
Rainbow trout
Crustacean
Crayfish
Daphnia magna
Mammals
Rat
Rat
Rat
Guinea pig
Rabbit
Birds
Chick
Mallard
j" ^ —
118. mgA 48 hr
60. mg/1 43 hr
1. mg/1 48 hr
650.
600.
620.
1250.
819.
1190.
2000.
Chronic Effects No Effect Level
100. mg/1 48 hr
PGBE 30 mgAg
'90 days
PGBE cow 25 mgAg 20 doses
PGBE sheep 25 mgAg 10 doses
33,700 mgAg 500 mgAg
Ukn, 13 day dose minor effects
Reference
Cope 1964
Cope 1964
Sanders 1970
Sanders 1970
Rowe & Hymas 1954
Rowe & Hymas 1954
Rowe & Hymas 1954
Rowe & Hymas 1954
Rowe & Hymas 1954
Tucker & Crabtree
1970
-------
Appendix Table I. (continued)
Chemical
Organism
Mammals and Birds
Acute Oral LDc-
mg/kg of Body Iffeight
Aquatic Organisms
Acute
Chronic Effects
No Effect Level
Reference
Herbicides (cont.)
Phenoxy
2,4,5-TP (Silvex)
PGBE ester
OJ
Birds (cont.)
Chicken
Fish
2000.
PGBE ester
isooctyl ester
potassium salt
BE ester
TE amine
acid
acid
PGBE ester
PGBE ester
BE ester
PGBE ester
Bluegill
Bluegill
Bluegill
Bluegill
Bluegill
Bluegill
Fathead minnow
Chinook
Largemouth bass
Crustaceans
Crayfish
Crayfish
Marine & Estuarine
25. mg/1 48 hr
5. mg/1 48 hr
83. mg/1 48 hr
2. mg/1 48 hr
20. mg/1 48 hr
2. mg/1 % hr
7.5 mg/1 96 hr
1.230 mg/1 48 hr
3.500 mg/1 24 hr
60. mg/1 48 hr
Eastern oyster, egg .0059 mg/1 48 hr
Eastern oyster, .710 mg/1 14 day
larvae
25,000 mg/kg 10 doses
wt. loss Palmer & Radeleff 1969
Mullison 1966
100. mg/1
Hughes & Davis 1966
Hughes & Davis 1966
Hughes & Davis 196c
Hughes & Davis 1966
Hughes & Davis 1966
Surber & Pickering 1961
Surber & Pickering 1961
Bond 19 59*
Bond 1959
Sanders 19"?:
Sanders 197C
Davis & Hidu 1969
Davis & Hidu 1969
-------
Appendix Table I. (continued)
Mamma la and Birds
Acute Oral LDjg
mg/kg of Body Weight
Aquatic Organisms
Acute LC^n Mg/1
Chemical
Herbicides (cont.)
Phenoxy ( cont . )
2,4-D acid
03.
(»
2,4-D ester
BE ester
2,4-D salt
DE amine
Urganlsm
Mannnals
Rat 375
Mouse 368
Birds
Chicken 540
Mallard 2000
Insect
Stonefly 1.6 mg/1 96 hr
Crustacean
Crayfish 60. mg/1 48 hr
Crayfish
Chronic Effects
TEA 1000 mg/1 in
water (120 days)
slower growth
Bjorklund & Erne
TEA 1000 mg/1 in
eggs. Bjorklund
i No Effect Level Reference
30 mg/kg Rowe & Hymas 1954
(4 weeks)
1966
water, fewer Tucker & Crabtree 1970
& Erne 1966
Sanders & Cope 1968
Sanders 1970
100. mgA 48 hr Sanders 1970
-------
Appendix Table I. (continued)
Mammals and Birds
Acute Oral LDj-
mg/kg of Body Weight
Aquatic Organisms
Chemical
Herbicides (cont.)
Phenoxy ( oont . )
2,4-D acid
2,4-D
DE amine
alkaloatm'ne
2,4-D ester
BE ester
PGBE ester
isooctyl ester
butyl ester
isopropyl ester
Organism
Fish
Bluegill
Bass
Bluegill
Bluegill
Fathead minnow
Bluegill
Bluegill
Bluegill
Bluegill
390. mg/1
375. mg/1
166. mg/1 48 hr
435. mg/1 48 hr
5.6 mg/1 96 hr
3. mg/1 48 hr
9. mg/1 48 hr
1. mg/1 48 hr
1. mg/1 48 hr
Chronic Effects No Effect Level Reference
5. mg/1 temporary 1. mg/1 Davis & Hardcastle 1959
liver changes. Cope et al. 1970
Davis & Hardcastle 1959
Lawrence 1964
Lawrence 1964
.3 mg/1 10 mos. Mount & Stephan 1967
Lawrence 1964
Lawrence 1964
Lawrence 1964
-------
Appendix Table I. (continued)
Uamnals and Birds
Acute Oral LDjg
mg/kg of Body Weight
Aquatic Organisms
Acute LC
Mg/1
O
nViptrn' cfll
Herbicides (cont.)
Phenoxy
2,4,5-T
acid
amyl ester
isopropyl ester
acid
isopropyl ester
butyl ester
acid
acid
acid
BE ester
isooctyl ester
PGBE ester
BE ester
dimethyl amine
Organism
Mammals
Rat 500. PGBE ca
Rat 750. PGBE sh
Rat 495. TEA she
Mouse 389.
Mouse 550.
Mouse 940 .
Guinea pig 380.
Dog 100.
Birds
Chicken 310.
Fish
Bluegill 1.4 mg/1 48 hr
Bluegill 10. -31. mg/1 48 hr
Bluegill 17. mg/1 48 hr
Bluegill 1.4 mg/1 48 hr
Bluegill 144. mg/1 48 hr
Chronic Effects No Effect Level Reference
No Effect Level
ttle 100 mgAg/d, 10 d^i Palmer & Howe & Hymas 1954
eep 50 mgAg/d, 10 d >Radeleff Rowe & Hymas 1954
ep 100 mgAg/d, 481 d J 1969 Rowe & Hymas 1954
Rowe & Hymas 1954
Rowe & Hymas 1954
Rowe & Hymas 1954
Chronic Effects R^we & H,TO= 1Q^|
10 mgAg/d, 90 d, Dalgaard-Mikkelsen & Paulsen
minor wt. loss 1962
Drill & Hiratzka 1953
PGEE 10 mg/kg/d Rowe & Hymas 1954
10 days
Palmer 8c Radeleff 1969
Hughes & Davis 1963
Hughes & Davis 1963
Hughes & Davis 1963
Bond et al. 1959
Bond et al. 1959
-------
Appendix Table I. (continued)
Mammals and Birds
Acute Oral LDjg
fflg/kg of Body Weight
Aquatic Organisms
Acute LC;a Mg/1
Chemical Organism Chronic Effects No Effect Level Reference
Herbicides (cont.)
Phenoxy (contaminant)
2,3,7,8-tetrachlorodibenzoidioxin (impurity in silvex and 2,4,5-T)
(TCDD)
l_j Mammals
M Rat -022 Schwetz et_ a^. 1973
Mouse .1H Vos e^ a^. 1973
K&bbit .115 Rosen & Kraybill 1966
Dog 3. Rosen & Kraybill 1966
Guinea pig .0006 Rosen & Kraybill 1966
Fish
Rainbow trout .0000054 mgA 120 hrs Miller et al. 1973
Coho salmon < .000023 mgA 120 hrs Miller it" IT. 1973
Gu-ppy < -0001 mgA Norris & Jfiller 1974
-------
Appendix Table I. (continued)
ro
Mammals and Birds
Acute Oral LDjg
mg/kg of Body Weight
Aquatic Organisms
Acute LCcn Mg/1
Chemical
Insecticides
Carbamates
Carbaryl
(Sevin)
Organism
Mammals
Rat
Guinea pig
Rabbit
Birds
Chicken
Fish
Fathead minnow
Bluegill
Largemouth bass
Rainbow trout
Brown trout
Coho salmon
Channel catfish
Black bullhead
Carp
Gold fish
Perch
Insects
Stonefly
500.
280.
710.
197.
9.000 mg/1 96 hr
6.760 mgA 96 hr
6.400 mg/1 96 hr
1.950 mg/1 96 hr
1.950 mg/1 96 hr
.764 mg/1 % hr
15.800 mg/1 96 hr
20.000 mg/1 96 hr
5.280 mg/1 96 hr
13-200 mg/1 96 hr
.745 mg/1 96 hr
.0048
Chronic Effects No Effect Level Reference
Matsumura 1975
Pest. Chem. Of. Comp. p. 192, 1966
Pest. Chem. Of. Comp. p. 192, 1966
Sherman & Ross 1961
Fathead minnow .0002 Carlson NWQL
Macek & McAllister 1970
Macek & McAllister 1970
Macek & McAllister 1970
Macek & McAllister 1970
Macek & McAllister 1970
Macek & McAllister 1970
Macek & McAllister 1970
Macek & McAllister 1970
Macek & McAllister 1970
Macek & McAllister 1970
Sanders & Cope 1968
-------
Appendix Table I. (continued)
Chemical
Organism
Mammals and Birds
Acute Oral U^Q
mg/kg of Body Weight
Aquatic Organisms
Acute LC5Q
Chronic Effects
No Effect Level
Reference
Insecticides (cont.)
Carbamates (cont.)
Carbaryl
(Sevin) (cont.)
Organochlorine
Endosulfan
(Thiodan)
Crustaceans
Crayfish
Red crayfish
Daphnia pulex
Marine & Estuarine
Dungeness crab
Am. oyster larv.
Pac. oyster larv.
Bay mussel larv.
Mud shrimp
Ghost shrimp larv.
Bent-nosed clam
Cockle clam
Mammals
Rat
Birds
Duck
Cowbird
Bobwhite, young
Pheasant
.0086 mg/1 96 hr
2.000 mg/1 72 hr
.0064 mg/1 48 hr
.180 mg/1 96 hr
3.000 mg/1 14 day
2.200 mg/1 96 hr
2.300 mg/1 % hr
.090 mg/i 48 hr
,080 mg/1 48 hr
1.700 mg/1 96 hr
3.750 mg/1 96 hr
100.
30.-79.
1200.
380.
850.
Sanders & Cope 1968
Muncy & Oliver 1963
Sanders & Cope 1966
Buchanan et_ al. 1967
Davis & Hldu 1969
Stewart et_ al. 1967
Stewart et_ al_. 1967
Stewart et_ al_. 1967
Stewart e_t al. 1967
Armstrong & Millemann 1974
Butler et al. 1968
Schafer 1972
Matsumura 1975
Matsumura 1972
DeWitt et_ a^. 1962
DeWitt et_ al_. 1962
DeWitt et al. 1962
-------
Appendix Table I. (continued)
Mammals and Birds
Acute Oral LDjg
mg/kg of Body Weight
Aquatic Organisms
Acute LC
Chemical
Organism
SO.
Mg/1
Chronic EffectsNo Effect Level
Reference
vD
Insecticides (cont.)
Organochlorine (cont.) Fish
Endosulfan
(Thiodan) (cont.)
Rainbow trout
White sucker
Insects
Stonefly
Damselfly naiads
Crustaceans
Daphnia magna
Scud
Marine & Estuarine
Bay mussel
.0003 mg/1 96 hr
.003 fflg/1 96 hr
.0023 mg/1 96 hr
.072 mg/1 96 hr
.052 mg/1 96 hr
.006 mg/1 96 hr
1000 mg/1, delayed spavining
Schoettger 1970
Schoettger 1970
Sanders & Cope 1968
Schoettger 1970
Schoettger 1970
Sanders 1972
Lin & Lee 1975
Endrin
Mouse
Rat
Rabbit
Guinea pig
Birds
Pigeon
1.37
3.
7.
16.
5.6
Dog .02 mgAg/day Treon et al. 1955
-------
Appendix Table I. (continued)
Chemical
Organism
Mammals and Birds
Acute Oral LDjQ
mg/kg of Body Weight
Aquatic Organisms
Acute LC5Q Mg/1
Chronic Effects
No Effect Level
Reference
Insecticides (cent. )
Organochlorine (cont.) Fish
Endrin (cont.)
H
Fathead minnow
Bluegill
Rainbow trout
Coho salmon
Chinook salmon
Cutthroat trout
.0005 mg/1 96 hr
.0006 mg/1 % hr
.0006 mg/1 96 hr
.0005 mg/1 96 hr
.0012 mg/1 96 hr
.00011 mg/1 96 hr
Striped bass (Juv. ) .00009-; mg/1 96 hr
Insects
Stonefly
Stonefly
Crustaceans^
Scud
Crayfish
Daphnia
Marine & Estuarine
Sand shrimp
Hermit crab
.0024 mg/1 96 hr
.00032 mg/1 96 hr
.0009 mg/1 120 hr
.0032 mg/1 96 hr
.020 mg/1 48 hr
.0017 mg/1 96 hr
.012 mg/1 96 hr
Henderson et al. 1959
Henderson et^ al. 1959
Katz 1961
Katz 1961
Katz 1961
Post & Schroeder 1971
Korn & Earnest 197^
Jensen & Gaufin 1966
Jensen & Gaufin 1966
Sanders 1972
Sanders 1972
Sanders & Cope 1966
Eisler 1969
Eisler 1969
-------
Appendix Table I. (continued)
Chemical
Organism
Mammals and Birds
Acute Oral LDjn
ng/ig of Body Weight
Aquatic Organisms
Acute LC5n Mg/1
Chronic Ki'i'ects No Effect Level
Reference
Insecticides ( cont. ]
Organochlorine
Lindane
Mammals
Rat
Rabbit
Guinea pig
Birds
Chicken
Pheasant
Chukar
Bobwhite
Morning dove
Fish
Fathead minnow
Bluegill
Redear sunfish
Largemouth bass
Rainbow trout
Brown trout
Coho salmon
Perch .
88.
60.
127.
250.
75.-100.
35.-185.
120.-130.
350,-400.
.087 mg/1 96 hr
.068 mg/1 96 hr
.083 mg/l 96 hr
.032 mg/i 96 hr
.027 mg/i % hr
.002 mg/1 96 hr
.0^1 mg/1 96 hr
.068 mgA 96 hr
Gaines 1960
Woodard & Hagan 1947
Woodard & Hagan 1947
Grolleau 1965
Grolleau 1965
Grolleau 1965
Dahlen & Gaugen 1954
Dahlen & Gaugen 1954
Macek
Macek
Macek
Macek
Macek
Macek
Macek
Macek
& McAllister
& McAllister
& McAllister
& McAllister
& McAllister
& McAllister
& McAllister
& McAllister
1970
1970
1970
1970
197C
1970
1970
1970
-------
Appendix Table I. (continued)
Chemical
Organism
Mammals and Birds
Acute Oral LDj..
mg/kg of Body Weight
Aquatic Organisms
Acute LC5Q
Chronic EffectsNo Effect Level
Reference
Insecticides (cont.)
Organochlorine (cont. )
Lindane
Organophosphorus
Diazinon
Fish (cont.)
Channel catfish
Guppies
Gold fish
Carp
Black bullhead
Insects
Stonefly
Crustaceans^
Daphnia pulex
Marine & Estuarine
.044 mg/1 96 hr
.138 mg/1 96 hr
.152 mg/1 % hr
.090 mg/1 96 hr
.064 mg/1 96 hr
.0045 mg/1 96 hr
.460 mg/1 96 hr
Eastern oyster - 9.100 mg/1 48 hr
egg
Hard clam - larvae > 10.000 mg/1 12 day
Hermit crab .005 mg/1 96 hr
Mammals
Rat
Mouse
76.
85.
Macek & McAllister 1970
Tarzwell 1958
Tarzwell 1958
Macek & McAllister 1970
Macek & McAllister 1970
Sanders 4 Cope 1968
Sanders & Cope 1966
Davis & Hidu 1969
Davis & Hidu 1969
Eisler 1969
Schafer 1972
Guide to Chem. Used in Crop Prot. 6:171, 1973
-------
Appendix Table I. (continued)
CO
Mammals and Birds
Acute Oral LDjQ
mg/kg of Body Weight
Aquatic Organisms
Acute LC
Chemical
Organism
5n
Chronic EffectsNo Effect Level
Reference
Insecticides (cont.)
Organophosphorus (cont.)Birds
Diazinon (cont.)
Disulfoton
Bird
Mallard
Pheasant
Fish
Rainbow trout
Bluegill
Insects
Stonefly
Crustaceans
Daphnia pulex
Daphnia magna
Mammals
Rat
Rat - skin
Birds
Bobwhite, young
3.5
4.3
170. mg/1 48 hr
30. mg/1 48 hr
25. mg/1 96 hr
.9 mg/1 48 hr
12.5
6.
.26 mg/1
Schafer 1972
Tucker & Crabtree 1970
Tucker & Crabtree 1970
Cope 1964
Cope 1964
Sanders & Cope 1968
Sanders & Cope 1966
Biesinger NWQL
Frawley et_ al. 1963
Gaines 1969
DeWitt et al. 1962
-------
Appendix Table I. (continued)
Chemical
Organism
Mammals and Birds
Acute Oral LDc_
mg/kg of Body Weight
Aquatic Organisms
Acute LCgp Mg/1
Chronlc Effects
No Effect Level
Reference
Insecticides ( cont. )
Organophosphorus (cont. ) Fish
DLsulfoton (cont.)
sD
Fenitrothion
(Sumithion)
Fathead minnow
Bluegill
Insects
Stone fly
Crustaceans
Scud
Glass shrimp
Mammals
Rat
Ifouse
Birds
Chicken
Wild bird
Fish
Brook trout
.063 mg/1 96 hr
3.700 mg/1 96 hr
.005
.027
.038
250.
715.
280.
25.
.0017 mg/1 (30 day LC )
Jensen & Gaufin 1964
Pickering et al. 1962
Pickering et al. 1962
Sanders & Cope 1968
Sanders 1972
Sanders 1972
Schafer 1972
Cherkinskii et al. 1966
Sherman et al. 1967
Schafer 1972
Loss of established hierar-
chical order. 4 weeks of 10 mg/g
dosage in food.
Wildlsh & Lister 1973
-------
Appendix Table I. (continued)
Chemical
Organism
Mammals and Birds
Acute Oral LDjn
mg/kg of Body Weight
Aquatic Organisms
Acute LC5n Mg/1
Chronic EffectsNo Effect Level
Reference
Insecticides (cont.)
Organophosphorus (cont.) Fish ( cont. )
Fenitrothion (cont.) Atlantic salmon
(Sumithion)
O
O
Guthion
azlnphosmethyl
Mammals
Rat
Guinea pig
Birds
Chicken
Fish
Rainbow trout
Brown trout
Coho salmon
Chinook' salmon
Redear sunfish
Bluegill
Fathead minnow
1.000 mg/1 96 hr
15.
80.
277.
.014 mg/1 % hr
.017 mg/i 96 hr
.005 mg/1 48 hr
.0062 mg/1 48 hr
.052 mg/1 96 hr
.022 mg/1 96 hr
.093 mg/l 96 hr
1. mg/1, 16 hrs loss of
territorrial behavior.
24 hrs loss of learning ability
(Symons 1973), and increasing
predation by brook trout
(Hatfield et al. 1972).
Hatfield & Johansen 1972
Chem. of Pest. 1971
Pest. Chem. Office Corp., p. 570, 1966
Sherman et al. 1967
Macek & McAllister 1970
Macek & McAllister 1970
Katz 1961
Katz 1961
Macek & McAllister 1970
Macek & McAllister 1970
Henderson 1959
-------
Appendix Table I. (continued)
Chemical
Organism
Mammals and Birds
Acute Oral LD5Q
mg/kg of Body Weight
Aquatic Organisms
Acute LC50
Chronic Effects
No Effect Level
Reference
o
Insecticides (cont.)
Organophosphorus (cont.) Fish (cont.)
Guthion Channel catfish
azinphosmethyl (cont.) Black bullhead
Goldfish
3.290 mg/1 96 hr
3.500 mg/1 % hr
4.270 mg/1 96 hr
Insects
Stonefly
Marine & Estuarine
Eastern oyster,
egg
Hard clam, larvae
Malathion
Mammals
Rat
Fish
Fathead minnow
Bluegill
Redear sunfish
.0015 mg/1 96 hr
.620 mg/1 48 hr
.860 mg/1 12 day
599.
9.000 mg/1 96 hr
.110 mg/1 96 hr
.170 mg/1 96 hr
Macek & McAllister 1970
Macek & McAllister 1970
Macek & McAllister 1970
Sanders & Cope 1963
Davis & Kidu 1969
Davis & Hidu 1969
Boyd & Taylor 1971
.580 10 mo., spinal defects Mount & Stephan 1967
.0074 .200 1C mo. Eaton 1971
spinal defects
.0036 Macek & McAllister 1970
11 mo.
-------
Appendix Table I. (continued)
Mammals and Birds
Acute Oral LDjg
mg/kg of Body Weight
Aquatic Organisms
Acute LC«n Mg/1
Chemical
Organism
Uhronlc El'i'ects No Effect Level
Reference
Insecticides ( cont.)
Organophosphorus (cont.) Fish (cont.)
Malathion (cont. )
IV)
o
FO
Largemouth bass
Rainbow trout
Brown trout
Coho salmon
Perch
Channel catfish
Carp
Goldfish
Black bullhead
Insects
Stonefly
Crustaceans
Red crayfish
Crayfish
Daphnia pulex
.285 mgA 96 hr
.170 mg/1 96 hr
.200 mg/1 96 hr
.100 mg/1 96 hr
.263 mgA 96 hr
8.970 mg/1 96 hr
6.590 mg/1 96 hr
10.700 mg/1 96 hr
12.900 mg/1 96 hr
.010 mg/1 96 hr
.180 mgA 96 hr
.0018 mg/1 96 hr
.112 10 days
Post et_ al. 1974
45$ reduction in AChE
20 mg/1
Macek & McAllister 1970
Macek & McAllister 1970
Macek
Macek
Macek
Macek
Macek
Macek
Macek
& McAllister
& McAllister
& McAllister
& McAllister
& McAllister
& McAllister
& McAllister
1970
1970
1970
1970
1970
1970
1970
Sanders & Cope 1968
Muncy & Oliver 1964
Sanders 1970
Sanders & Cope 1966
-------
Appendix Table I. (continued)
o
Mammals and Birds
Acute Oral LDjQ
mg/ig of Body Weight
Aquatic Organisms
Acute LC5Q
Chemical
Insecticides ( cont. )
Organophosphorus ( cont .
Malathion ( cont . )
Phosphamidon
(Dimecron)
*
Organism
) Marine & Estuarine
Eastern oyster
egg
Eastern oyster
larvae
Bay mussel
embryo
Hermit crab
Mammals
Rat
Mouse
Rabbit
Dog
Birds
Mallard
Pigeon
Chukar
Fish
Fathead minnow
Bluegill
Channel catfish
Chronic Effects No Effect Level Reference
9.
2.
13-
•
17.
10.
70.
50.
3.
3.
9.
100
4.5
70.
070 mgA 48 hr
660-mg/l 12 day
400 mg/1 12 day
083 mg/1 96 hr
. mg/1 96 hr
mg/1 96 hr
mg/1 96 hr
Davis & Hidu 1969
Davis & Hidu 1969
.
Liu & Lee 1975
Eisler 1969
Schafer 1972
Sachsse & Voss 1971
Sachsse & Voss 1971
Sachsse & Voss 1971
Sachsse & Voss 1971
Sachsse & Voss 1971
FPRL
FPRL
FPRL
-------
Appendix Table I. (continued)
Chemical
Organism
Mammals and Birds
Acute Oral LDjn
nig/kg of Body Weight
Aquatic Organisms
Acute LC5n
Chronic ElTectsNo Effect Level Reference
Insecticides (cont.)
Organophosphorus (cont.) Insects
Stonefly
Phosphamidon
(Dimecron)
o
-JS-
Trichlorfon
(Dipterex)
Crustaceans
Scud
Crayfish
Daphnia
Mammals
Mouse
Rat
Fish
Fathead minnow
Bluegill
Insects
Stonefly
Stonefly
Crustaceans
Scud
Daphnia
.15 mg/1 96 hr
.016 mg/1 96 hr
7.5 mg/1 96 hr
.0088 mg/1 96 hr
600.
400.
109. mg/1 96 hr
3.8 mg/1 96 hr
.069 mg/1 96 hr
.0165 mg/1 % hr
.040 mg/1 96 hr
.00018 mg/1 96 hr
Sanders & Cope 1968
Sanders 1972
Sanders 1972
Sanders & Cope 1968
Schafer 1972
Pickering et al. 1962
Pickering et al. 1962
Jensen & Gauffin 1966
Jensen & Gauffin 1966
Sanders & Cope 1966
Sanders & Cope 1966
-------
Appendix Table I. (continued)
Chemical
Organism
Mammals and Birds
Acute Oral LDj-.
mg/kg of Body Weight
Aquatic Organisms
Acute LC5Q Mg/1
Chronic Effects
No Effect Level
Reference
Abreviations: AChE - acetylchollnesterase
BE - butoxy ethyl
PGBE - propyleneglyco butylether
TE - triethyl
TEA - triethylamine
EE - diethyl
d - day or days
O
VJl
-------
Appendix n
REFERENCES FOR APPENDIX TABLE 1
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with the insecticide Sevin in the bent-nosed clam, Macoma nasuta. J.
Invert. Path. 24:201-212.
Bailey, George W., and Joe L. White. 1965. Herbicides: a compilation of
their physical, chemical, and biological properties. Res. Rev. 10:97-
122.
Ben-Dyke, R., D. M. Sanderson, and Diana N. Noakes. 1970. Acute toxicity
data for pesticides. World Review of Pest Control 9:119-127.
Biesinger, K. E. 1971. Unpublished data, Env. Prot. Agency, Nat. Water
Quality Lab., Duluth, Minnesota 55804.
Bond, C. E., R. H. Lewis, and J. L. Fryer. I960. Toxicity of various her-
bicidal materials to fishes. Robert A. Taft Sanit. Eng. Center
Tech. Rept. W60-3:96-101.
Bough, R. G., E. E. Cliffe, and B. Lessel. 1965. Comparative toxicity and
blood level studies on Binapacryl and DNBP. Toxicology and Applied
Pharmacology 7:353-360.
Boyd, EldonM., and Frances I. Taylor. 1971. Toxaphene toxicity in protein-
deficient rats. Toxicology and Applied Pharmacology 18:158-167.
Buchanan, D. V., R. E. Millemann, and N. E. Stewart. 1970. Effects of the
insecticide Sevin on various stages of the Dungeness crab, Cancer
magister. J. Fish. Res. Bd. Can. 27:93-104-
Butler, J. A., R. E. Millemann, and N. E. Stewart. 1968. Effects of the
insecticide Sevin OR survival and growth of the cockle clam
Clinocardium nuttallii. J. Fish Res. Bd. Can. 25:1621-1635.
Cherkinskii, S. N., K. I. Akulov, and G. N. Krasovskii. 1966. Relative
toxicity of various pesticides which may pollute water sources.
Hygiene and Sanitation 31:18-22.
Cope, Oliver B. 1964. Sport fishery investigations. In: The effects of
pesticides on fish and wildlife. USDI FW Service Circ. 226. p. 51-63.
Dalgaard-Mikkelsen, S. and E. Poulsen. 1962. Toxicology of herbicides.
Pharmacological Revues 14:225.
206
-------
Davis, H. C., and H. Hidu. 1969. Effects of pesticides on embryonic devel-
opment of clams and oysters and on survival and growth of the larvae.
U.S. Fish and Wildl. Serv., Fish. Bull. 67:393-404.
DeWitt, J. B., W. H. Stickel, and P. F. Springer. 1963. Wildlife studies.
Patuxent Wildl. Res. Cntr. U.S. Dept. Int. Fish and Wildl. Serv.
Circ. 167:74-96.
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208
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209
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210
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211
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Appendix
CHECKLIST OF SPECIES FOR WHICH TOXICTTY DATA IS GIVEN
Fish
Common Name
Atlantic salmon
Brook trout
Brown trout
Brown bullhead
Black bullhead
Bluegill sunfish
Channel catfish
Carp
Chinook salmon
Coho salmon
Cutthroat trout
Fathead minnow
Green sunfish
Goldfish
Guppy
Largemouth bass
Perch
Rainbow trout
Redear sunfish
Striped bass
White sucker
Scientific Name
Salmo salar
Salvelinus fontinalis
Salmo trutta
Ictalurus nebulosus
Ictalurus melas
Lepomis machrochirus
Ictalurus punctatus
Cyprinus carpio
Oncorhynchus tschawytscha
Oncorhynchus kisutch
Salmo clarki
Pimephales promelas
Lepomis cyanellus
Carassius auratus
Lebistes reticulatus
Mcropterus salmoides
Perca flavescens
Salmo gairdnerii
Lepomis microlophus
Morone saxatilis
Catostomus commersoni
212
-------
Crustaceans
Common Name
Crayfish
Crayfish, red
Dungeness crab
Hermit crab
Ghost shrimp
Glass shrimp
Mud shrimp
Sand shrimp
Scud
Water flea
Water flea
Bay mussel
Bent-nosed clam
Cockle clam
Eastern oyster
Hard clam
Bobwhite quail
Chuckar partridge
Cowbird
Mallard duck
Molluscs
Birds
Scientific Name
Oronectes nais
Procambarus clarki
Cancer magister
Pagurus longicarpus
Callianassa californiensis
Palaemonetes kadiakensis
Upogebia pugettensis
Crangon septemspinosa
Gammarus fasciatus
Daphnia magna
Daphnia pulex
Mytillus edulis
Macoma nasuta
Clinocardium nuttallii
Crassostrea virginica
Mercenaria mercenaria
Colinus virginianus
Alectoris graeca
Melothris ater
Anas platyrhynchos
213
-------
Birds (cont.)
Common Name Scientific Name
Mourning dove Zenaidura macruora
Pigeon Co rumba livia
Insects
Damselfly Ischnura sp.
Stonefly Pteronarcys californica
214
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Appendix IV
GLOSSARY
Absorption:
Acclimatization:
Acute toxicity:
Adaptation:
Adsorption:
Aerobi c:
Algae:
Algicide:
Anadromous fish:
Anaerobic:
Anoxic:
Antagonistic:
Application factor:
Assimilation:
The incorporation of one substance within
another.
Adjustment of an organism to changes in its
environment.
A single dose has more effect than the same
quantity administered in several applications.
An anatomical, behavioural or physiological
change in an organism which better enables it
to survive in its environment.
The adhesion of one substance to the surface of
another.
Associated with the presence of free oxygen.
A group of simple chlorophyll-containing plants,
mostly aquatic; although most are microscopic,
some forms reach extremely large sizes.
A chemical specifically toxic to algae, often
used to control algal blooms.
Fish spending most of their lives in the sea,
but ascending freshwater rivers to spawn.
Occurring in the absence of free oxygen.
Depleted of free oxygen; anaerobic.
Causing reduction of toxicity of another chemi-
cal.
A factor applied to the results of a short-term
toxicity test to estimate the safe concentration
of a substance or mixture of substances in water,
The transformation of absorbed nutrients into
body substances or the process whereby a body
of water purifies~~itself of organic pollution.
215
-------
Bacteria:
Benthic region:
Benthos:
Bioaccumulation:
Bioassay:
Biochemical oxygen
demand (BOD):
Biodegradable:
Biological monitoring:
Biomass:
Biota:
Bloom:
Blue-green algae:
Body burden:
Brackish water:
Microscopic organisms lacking chlorophyll and
a definite nucleus, living either as single
cells or in filaments.
The bottom of a body of water; the organisms
inhabiting the benthic region are referred to
as the benthos; they contribute to the charac-
ter of the bottom.
The organisms living at the bottom of a sea,
lake, river or estuary; they may be attached
to the bottom, creep along its surface of
burrow into it.
Uptake and retention of environmental substances
by an organism from its environment.
The laboratory determination of the effects of
substances or conditions upon specific living
organisms.
A measure of the amount of oxygen consumed
(mg/l) in the biological processes that break
down organic matter in water.
Able to be decomposed readily by the action of
micro-organisms.
The use of living organisms to test the quality
of waters.
The weight of all life or of a given population
in a specified area.
All the living organisms within a certain area.
A readily visible proliferation of phyto-
plankton, macrophytes or zooplankton in a body
of water.
A group with a blue pigment in addition to the
green chlorophyll, often associated with blooms
and capable of fixing atmospheric nitrogen.
The total amount of a substance present in the
body tissues and fluids of an organism.
Water with salinity less than that of sea
water, but greater than that of fresh water.
216
-------
Buffer strip:
Carcinogenic:
Carnivore:
Catadromous fish:
Chemical oxygen demand
(COD)
Chlorophyll:
Chronic toxicity:
Coarse fish:
Cold-blooded animals
(poikilothermic animals):
Colloid:
Consumer:
Cultural eutrophication:
Cumulative:
Daphnia:
Detritus feeder:
Dispersant:
A zone left untreated; usually at the outer
margin of the treated area or adjacent to
streams.
Producing cancer.
An animal which eats other animals.
Fish spending most of their lives in fresh
water but spawning at sea.
A measure of the amount of oxygen required
(mg/l) to chemically oxidize organic matter
in the water.
The green pigments of plants which enable them
to use the energy of the sun for photosynthesis.
A single dose has less effect than the same
quantity of toxin applied in several smaller
doses.
Those fish species not desirable as game fish or
food fish.
Animals lacking a temperature-regulating
mechanism, whose temperature fluctuates with
that of their environment.
Very small particles (< 2 microns) which tend to
remain suspended and dispersed in liquids.
An organism that consumes either other organisms
or organic food material.
The acceleration by man of the build-up of nut-
rients in a body of water; this build-up is part
of the natural aging process of lakes, etc.,
but normally occurs quite slowly.
Brought about or increased in strength by suc-
cessive additions.
Water fleas, minute crustaceans which are valu-
able fish food.
An animal which feeds upon organic detritus.
A chemical agent, often a detergent, used to
break up concentrations of organic material,
e.g. oil spills.
217
-------
Diversity:
Ecology:
Ecosystem:
Effluent:
Emergent aquatic plants:
Enrichment:
Enteric:
Environment:
Epiphytic:
Estuary:
Eutrophication:
Eutrophic waters:
Evapotranspiration:
Exchange capacity:
Fauna:
Floating aquatic plants:
The abundance of numbers of species in a speci-
fied location.
The relationships of living things to one
another and to their environment.
A biological community together with the physi-
cal and chemical resources of its location.
Waste water, treated or not, discharged into
bodies of water.
Plants rooted at the bottom and projecting above
the surface of the water.
The addition of nutrients to a body of water.
Of or originating in the intestinal tract.v
The sum of all external influences and condi-
tions .
Living on the surface of a plant.
A partially enclosed coastal water body where
tidal effects are evident and fresh water
mixes with sea water.
The natural process of aging of lakes and other
water bodies, involving nutrient enrichment and
eventually leading to the drying up of the body
of water (see cultural eutrophication).
Waters with a rich supply of nutrients typic-
ally characterized by blooms of aquatic plants,
low water transparency and a low dissolved
oxygen content.
The combined loss of water from a given area
during a specified period of time by evapora-
tion from soil or water surface and transpira-
tion from plants.
The total ionic charge of the adsorption complex
active in the adsorption of ions.
Animal life.
Macrophytes that wholly or in part float on the
surface of the water (water lilies, etc.).
218
-------
Flocculation:
Flora:
Food chain:
Food web:
Fry:
Fungi:
Game fish:
Green algae:
Habitat:
Herbicide:
Herbivore:
Heterotrophic organism:
Homothermic animals:
Hypolimnion:
Impoundment:
Insecticide:
Intertidal:
Invertebrates:
The treatment process by which suspended colloi-
dal or very fine particles are assembled into
larger masses or floccules which eventually
settle out of suspension.
Plant life.
The transfer of food energy from producers
through a series of consumers, usually four or
five.
A series of interconnecting food chains.
Newly hatched fish; sac fry until the yolk sac
is absorbed; then advanced fry until 2.5 cm in
length.
Plants without chlorophyll which rely on organ-
ic nutrients.
Fish sought by sports fisherman.
Algae with pigments similar in color to those
of the higher plants.
The place where the organism lives.
A pesticide chemical used to destroy or control
the growth of undesirable plants.
An animal which feeds on plants.
See consumer.
See warm-blooded animals.
That region of a stratified lake extending below
the thermocline to the bottom of the lake.
A body of water confined by a dam, dike, flood-
gate or other barrier.
Pesticide substance intended to repel or destroy
insects.
The area along the shore of a sea or estuary be-
tweed the levels of high and low water.
Animals without backbones.
219
-------
Lethal:
Life cycle:
Limnology:
Littoral zone:
Load:
Lysimeter:
Macro-organisms:
Macrophytes:
Make-up water:
Mass median diameter:
Median lethal
concentration:
Median lethal dose:
Meromictic lake:
Me sotrophic:
Metabolites:
That concentration of a particular substance
in a suitable diluent (experimental water) at
which just 50$ of the test organisms are able
to survive for a specified period of exposure.
That dose of a substance lethal to just 50% of
the test organisms within a specified time
period.
Involving a stimulus or effect causing death
directly.
The series of stages an organism passes through
during its life time.
The study of the physical, chemical and biolo-
gical aspects of inland waters.
The region along the shore of a body of water.
The amount of a nutrient or other substance
discharged into a body of water.
A device to measure the quantity or rate of
water movement through or from a block of soil,
usually undisturbed and in situ or to collect
such percolated water for quality analysis.
Organisms visible to the unaided eye.
Plants visible to the unaided eye.
Water added to boiler, cooling tower, or other
system to maintain the volume of water.
Droplet diameter such that half the weight of a
spray deposit is in larger and smaller droplets.
See LC
50'
See
A lake in which complete vertical mixing does
not occur.
Having a moderate nutrient load resulting in
moderate productivity.
Products of metabolic processes.
220
-------
Methaemoglobin:
Micronutrient:
Micro-organisms:
Motile:
Necrosis:
Nutrients:
Oncogenesis:
Open water:
Organic detritus:
Overturn:
Parasite:
Parr:
Pathogenic:
Periphyton:
Pesticide:
Photosynthesis:
A non-functional haemoglobin produced by the
reaction of oxyhaemoglobin with nitrite.
Chemical element necessary in only small amounts
for growth and development, a trace element.
Minute organisms invisible or barely visible to
the unaided eye.
Capable of spontaneous movement.
The death of cellular material within the body
of an organism.
Substances essential as raw materials for the
growth of organisms.
Development of cancerous tissue.
Water areas unprotected by overhanging vegetation.
The particulate remains of disintegrated plants
and animals.
The physical phenomenon of vertical mixing
which occurs in a body of water following the
breakdown of stratification.
An organism living on or in the host organism
and obtaining nourishment at the expense of its
host for all or part of its life cycle.
A young fish, usually a salmonid, between the
larval stage and the time it begins migration
to the sea.
Causing or capable of causing disease.
Aquatic organisms attached or clinging to plants
or other surfaces projecting above the bottom
of a lake or stream.
Any substance used to kill organisms; includes
herbicides, insecticides, algicides, fungicides
and others.
The process by which simple carbohydrates are
produced from carbon dioxide and water by
living plant cells, with the aid of chlorophyll
and in the presence of light.
221
-------
Phytobenthos:
Phytoplankton:
Phytotoxic:
Piscicide:
Plankton:
Poikilothermic animals:
Producers:
Productivity:
Pulse contamination:
Recharge:
Reducers:
Release:
Reservoir:
River basin:
Runoff:
Safety factor:
Saprophytic:
Secondary treatment:
The plant life of the benthos.
The plant life of the plankton.
Poisonous to plants.
A substance used to destroy or control fish
populations.
Organisms of relatively small size that swim
weakly or drift with the water masses.
See cold-blooded animals.
Organisms which synthesize organic substances
from inorganic substances.
The rate of production of organic material.
A short-lived higher concentration of pollutant
followed by a rapid decline to a much lower
concentration or complete absence thereof.
To add water to the zone of saturation, as in
recharge of an aquifer.
Organisms which digest food outside the cell by
means of enzymes and then absorb the food into
the cell and reduce it to inorganic matter.
To eliminate competition of undesirable vegeta-
tion from established trees.
A pond, lake, tank or basin, natural or man-
made, used for the storage or control of water.
The total area drained by a river and its trib-
utaries.
That portion of precipitation or irrigation
water which flows across the ground surface,
eventually returning to the streams.
A numerical value applied to short-term data
from other organisms in order to approximate
the concentration of a substance that will not
harm or impair the organism being considered.
Living on decayed organic matter.
See biological (secondary) treatment.
222
-------
Sessile organisms:
Seston:
Sorption:
Species (singular and
plural):
Spodic horizon:
Standing crop:
Stratification:
Sublethal:
Submerged aquatic plant:
Substrate:
Subtidal:
Succession:
Surfactant:
Symbiosis:
Synergism:
Teratogen:
Thermocline:
Organisms which rest on or are attached to a
substance, without a supporting stalk.
All the particulate matter suspended in water.
Absorption or adsorption.
A natural, reproductively isolated, population
or group of populations which transmit specific
characteristics from parent to off-spring.
A layer in some acid soils in which colloidal
oxides of iron and aluminum have accumulated.
These oxides can tie up large amounts of phos-
phorus .
See biomass.
Separation into layers.
Involving a stimulus below the level that causes
death.
A macrophyte which is continuously submerged
beneath the surface of the water.
The underlying material on which an organism
moves or to which it is attached.
Below the level of low water in a sea or estuary.
The sequence of communities which replace one
another in a given area until a relatively
stable community becomes established.
A surface active agent; a component of deter-
gents.
Two organisms of different species living to-
gether, with benefit to one or both and harm to
neither.
The combination of the effects of separate sub-
stances such that the total effect is greater
than the sum of the individual effects.
A substance causing birth defects.
The layer in a body of water where the tempera-
ture difference is greatest per unit depth.
223
-------
Threshold dose:
Tolerance:
Toxicity:
Trophic level:
Turbidity:
Vertebrates:
Warm and cold-water
fish:
Warm-blooded animals
(homothermic animals);
The minimum dose of a substance necessary to
produce a measurable effect in the test organ-
ism.
Capacity to endure an environmental factor.
Potency of a toxic or poisonous substance or
combination of substances.
Position in the food chain (i.e. producer, con-
sumer, etc.).
Cloudiness of the water.
Animals with backbones.
Groups of fish distinguished by the adaptation
of the eggs to development in warm or cold water.
Animals with a temperature regulating mechanism
capable of maintaining a nearly constant body
temperature, independent of environmental tem-
perature fluctuation.
Adapted from "A compilation of Australian water quality criteria" Technical
Paper No. 7. Australian Water Resources Council, 1974. Barry T. Hart.
224
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-------
BIBLIOGRAPHIC DATA
SHEET
I. Report No.
Report o.
EPA - 910/9-77-036
3. Recipient's Accession No.
4. Title and Subtitle
SILVICULTURAL CHEMICALS AND PROTECTION OF WATER QUALITY
5. Report Date
JUNE 1977
6.
7. Author(s)
OREGON STATE UNIVERSITY
8. Performing Organization Kept.
V'J' N/A
9. Performing Organization Name and Address
OREGON STATE UNIVERSITY
SCHOOL OF FORESTRY
CORVALLIS, OREGON 97331
10. Project/Task/Work Unit No.
11. Contract/Grant No.
12. Sponsoring Organization Name and Address
U.S. ENVIRONMENTAL PROTECTION AGENCY
WATER DIVISION
1200 SIXTH AVENUE
SEATTLE. WA 98101
13. Type of Report & Period
Covered
FINAL
14.
is. supplementary NotesTHIS REPORT WAS PREPARED UNDER EPA CONTRACT #68-01-3553
BY OREGON STATE UNIVERSITY, CORVALLIS, OREGON.
u. Abstracts THIS REPORT IS A COMPREHENSIVE REVIEW OF MANAGEMENT PRACTICES INVOLVING
SILVICULTURAL CHEMICALS AND EVALUATES THESE IN RELATION TO BOTH WATER QUALITY AND
SILVICULTURAL OBJECTIVES. IT PRESENTS AN ARRAY OF PROCEDURES AND BEST PRACTICES
THAT PERMIT REACHING MANAGEMENT GOALS WITH NEGLIGIBLE IMPACT ON WATER QUALITY.
THE REPORT DISCUSSES THE GENERAL SCOPE OF CHEMICAL USAGE IN THE PRACTICE OF SILVI-
CULTURE, PRESENTS CRITERIA FOR LIMITING CONCENTRATIONS OF CHEMICALS IN WATER, COVERS
BEHAVIOR OF CHEMICALS USED IN SILVICULTURE OPERATIONS AND PRESENTS POLLUTION CONTROL
GUIDELINES.
17. Key Words and Document Analysis. !7o. Descriptors
SILVICULTURAL CHEMICALS FERTILIZER
HERBICIDES
PESTICIDES
WATER QUALITY PROTECTION
TOXICOLOGY
WATER MONITORING
CHEMICAL APPLICATION
CHEMICAL CONCENTRATION MAXIMA
SILVICULTURAL PRACTICES
17b. Identifiers/Open-Ended Terms
METHODS, PROCEDURES, PRACTICES FOR REDUCING WATER QUALITY DEGRADATION FROM THE
APPLICATION OF SILVICULTURAL CHEMICALS.
WATER QUALITY MONITORING IN SILVICULTURAL CHEMICAL APPLICATION.
EFFECTS OF AERIAL APPLICATION OF CHEMICALS AND ALTERNATIVE SILVICULTURAL
PRACTICES ON WATER QUALITY.
TOXICITY DATA FOR SILVICULTURAL CHEMICALS.
I7e. COSATI Field/Group
18. Availability Statement
RELEASE UNLIMITED
19.. Security Class (This
Report)
UNCLASSIFIED
20. Security Class (This
Page
UNCLASSIFIED
21. No. of Pages
232
22. Price
FORM NTis-38 (REV. io-7») ENDORSED BY ANSI AND UNESCO. THIS FORM MAY BE REPRODUCED
4 U S GOVERNMENT PRINTING OFFICE 1977-798-041/155 REGION 10
USCOMM-DC 8265-P74
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