800R77102
SD388
.54
NONPOINT SOURCE CONTROL GUIDANCE
SILVICULTURE
MARCH 1977
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Water Planning & Standards
WASHINGTON, D.C. 20460
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or _ *s>
~ " UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
APR 2 8 1977
SUBJECT: Transmittal of Document Entitled "Nonpoint Source Control
Guidance, Silviculture"
FROM : E. M. Notzon, Acting Director ,|
Water Planning Division £, fi\*
TO : All Regional Water Division Directors
ATTN: All 208 Coordinators
All Nonpoint Source Coordinators
TECHNICAL GUIDANCE MEMORANDUM: TECH 3 "/
Purpose
Attached is a recently prepared nonpoint source control document that
identifies, defines, and structures the form and sequence of the water
quality management process in relation to silviculture. It presents a
methodology for the water quality management planner and persons
knowledgeable in silvicultural practices at the State and local level
to work closely and in a complementary manner for the development
of silvicultural Best Management Practices (BMP).
Guidance
The document is part of a series. Additional issues include construction,
mining, agriculture, and hydrologic modification. The series is designed
to provide State and 208 areawide agencies, Federal agencies and various
publics with information to assist them in carrying out their water
quality planning and implementation responsibilities.
These documents are provided in accordance with policies and procedures
of 40 CFR, Part 131 -- "EPA will prepare guidelines concerning the
development of water quality management plans to assist State and areawide
planning agencies in carrying out the provisions of these regulations."
This silviculture document is not designed to present the answers --
"the BMP" -- for application on a given tract of land. The diversity of
our forested land is much too broad for such an approach. The document
is designed to present an approach for carrying out the BMP concept as
it relates to silvicultural activities. This approach may then be
refined and added to with local knowledge by local people.
The described method inquires into the technical aspects of identifying
and assessing existing and future silvicultural nonpoint source problems,
analyzing the problems, and developing procedures needed for designing
localized BMP. This method recognizes the need for flexibility in water
quality management agencies. Following this, descriptions and examples
of BMP are presented for the defined conditions.
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NONPOINT SOURCE CONTROL GUIDANCE
FOR
SILVICULTURE
J. ROBERT SINGER RALPH C. MALONEY
U. S ENVIRONMENTAL PROTECTION AGENCY
WATER PLANNING DIVISION
NONPOINT SOURCES BRANCH
WASHINGTON, D. C. 20460
MARCH 1977
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ACKNOWLEDGEMENT
We appreciate the cooperation of the many people in various professional
fields within the U. S. Environmental Protection Agency (EPA) and other
Federal government agencies, environmental organizations, universities,
the forest industry, and private forest consulting work in providing con-
structive observations and much of the information used in preparing this
document.
All photographs courtesy of U. S. Forest Service.
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PREFACE
Section 208 of Public Law 92-500 requires that water quality management
planning include a process that identifies nonpoint sources of pollution,
including those associated with silviculture and related runoff, and establishes
procedures and methods to control these sources, to the extent feasible in
a given locale. This document is EPA guidance on Best Management
Practices for Silviculture developed pursuant to Section 208.
For purposes of this guidance, silviculture is defined as that part of
forest management which deals with the husbandry of forest crops. The
term includes all activities related to this purpose from the preparation
of an area for restoration of forest vegetation, through the establishment,
culture and protection of the growing crop, to that crop's harvest and
transport from the production area.
Every State has areas where silvicultural activities such as tree planting,
tree cutting, tree stand improvement or similar cultural practices take
place. Commercial timberlands on which silviculture may be a major activity
comprise a significant part of the forest land of the Nation, except in the
Great Plains region, parts of Alaska, and some of the Southwest. Twenty-
seven percent of the commercial timberlands are publicly owned. Seventy-three
percent are privately owned -- of these 59 percent are in small private
holdings and farm woodlots and 14 percent are held by private industry.
Significant differences in timberland ownership patterns and forestry
programs in various parts of the Nation will influence not only the water
quality program but also the regulatory, institutional, and public participation
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arrangements. For example, in the East only one-fourth of the commercial
timberlands are Federally owned, with the remainder being in small private
timber holdings, farm woodlots, and industrial timberlands. In the Northwest
a major portion of the commercial timberlands are Federally owned.
This guidance will identify, define, and structure the form and sequence
of the water quality management planning process in relation to silviculture.
It msiy be used to:
1., Guide development of more focused, refined and detailed
procedures by local experts -- procedures that reflect local
practicality, site-specific information, and implementation of the
Best Management Practices (BMP) concept;
2. Guide the identification and application of relevant, technical forestry
knowledge of nonpoint source pollution control practices appropriate
to solve local water quality problems caused by silvicultural activities;
and
3. Guide the design of program management to attain optimum
silvicultural contribution to the water quality management program.
While this guidance does not specifically address aspects of forest
management other than silviculture, it does establish a process that can
be applied in controlling other nonpoint source water pollution problems
associated with forest recreation use and with activities involving the
deliberate modification or change in vegetative cover. These may include
changes made to meet other forest land management objectives, such as
wildlife habitat improvement, water yield improvement, and fire hazard
reduction.
Interactions are extremely complex between the many variables which
affect both the natural pollutant loads of streams and water bodies and the
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degree to which silvicultural activities modify these loads. Therefore, the
interactions among the physiographic, biologic, and climatic characteristics
that created the inherent water pollution hazard of an area are carefully
examined and related to the characteristics and sensitivity of receiving waters.
Existing or potential impacts of silvicultural activities and practices on water
quality are analyzed in the context of these interactions.
Using this procedure, very complex problems can be systematically
reduced to a series of interrelated, but relatively simple, problems that can
be resolved with technical knowledge. A first step towards BMP develop-
ment is the definition of BMP design criteria. This is followed by identification
of alternative, technical solutions to meet these criteria by persons knowledge-
able on silvicultural operations and their relation to water quality.
Following these steps, the technically practical silvicultural BMP
can be made consistent with legal, institutional, economic and social consider-
ations to yield an implementable BMP. The purpose of the silvicultural
BMP is to prevent and/or reduce the pollution of waters from silvicultural
activities.
The silvicultural BMP, together with BMP of other nonpoint categories
which contribute to the water pollution problem in the drainage area,
can be analyzed to determine their respective contribution to the protection
and propagation of fish, shellfish and wildlife, and in providing for water-
oriented recreation. The BMP that achieves national goals and supports
program emphasis required to meet other local water quality goals can
then be identified for each category.
Implementation schedules of selected BMP for each category must be
established. The manpower, funding, technical knowledge, and legal basis
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needed to obtain the first round of pollution control should be identified.
Then, the institutional mechanisms and the responsibility for implementation
of a successful water quality management program can be defined and
scheduled. At that time, the machinery will be in place for successful
definition of information needed to monitor and enforce silvicultural BMP.
The methodology presented in this guidance is structured to allow different
levels and intensities of planning and implementation. It concentrates on
leading the planner to identify actual problem areas and on procedures to
help the planner establish an appropriate technical framework fo>r effective,
practical corrective action. It fosters the interchange of ideas and information
between the water quality management planner and professionals in the
field of forestry, forest hydrology, aquatic biology, and allied disciplines.
The expertise for application of available technology is presently
centered in Federal and State forestry agencies, in the more progressive
companies within the forest industry, in the academic community, and in a
few consultant firms. EPA has been using this expertise in developing
both program and technical guidance and in promoting technical assistance
to and through the State forestry organizations.
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TABLE OF CONTENTS Chapter
and
Page
PROGRAM INFORMATION NEEDS AND CHECKLIST 1-1
Program Information Needs 1-2
Program Checklist 1-3
SILVICULTURE IN RELATION TO WATER QUALITY MANAGEMENT II-l
Description of Activities II-l
Disturbances Associated with Silvicultural Activities II-6
Soil and Vegetation Disturbance II-7
Natural Drainageway and Stream Channel Disturbance 11-10
Potential Pollutants from Activities 11-11
Best Management Practices 11-12
ASSESSMENT, ANALYSIS, AND BMP DESIGN FOR SILVICULTURAL
PRACTICES III-l
Assessment III-4
Determination of Inherent Pollution Hazards III-4
Interpretation and Analysis III-7
Interactions III-9
Activity Identification and Evaluation III-11
Establishing Appropriate BMP Design Criteria 111-12
POLLUTION CONTROL PRACTICES IV-1
Prevention Practices IV-3
Reduction Practices IV-11
Considerations for Specific Land Areas IV-27
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LIST OF FIGURES Chapter
and
page
1 - NONPOINT POLLUTION CONTROL PROCESS FOR SILVICULTURE III-3
2 - IMPROPER DATA INTERPRETATION III-6
3 - EXTREMELY HIGH INHERENT POLLUTION HAZARD III-10
4 - TRACTOR HARVESTING OPERATION IV-6
5 - CABLE HARVESTING OPERATION IV-7
6 - PREPLANNED STREAMSIDE MANAGEMENT AREA IV-8
7 - WELL LOCATED MAIN ROAD IV-8
8 - ROAD CROSSING A MEADOW IV-9
9 - LOW USE ROAD IV-9
10- TRA.CTOR ROAD IV-10
11- MULCH ON ROAD FILL IV-15
12- LOG BRIDGE IV-16
13- ABANDONED LOGGING ROAD IV-16
14- LOG-HAUL ROAD IV-17
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LIST OF TABLES
Chapter
and
Page
1 - FRAMEWORK FOR PREVENTION AND REDUCTION
WATER POLLUTION CONTROL PRACTICES IV-2
2 - PRINCIPAL TYPES OF REDUCTION PRACTICES
FOR EROSION CONTROL APPLICABLE TO
SILVICULTURAL ACTIVITIES IV-12
3 - PRINCIPAL TYPES OF PESTICIDES PRACTICES
APPLICABLE TO SILVICULTURAL ACTIVITIES IV-25
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CHAPTER 1
PROGRAM INFORMATION NEEDS, AND CHECKLIST
Program Information Needs
During the planning process, the nonpoint source categories (i. e.,
silviculture, agriculture, construction, etc. ) which contribute to the
pollution problem, as well as the extent to which they contribute, should
be identified. Appropriate BMP for the situation should be selected and
decisions should be made as to how and where these BMP can most
effectively be scheduled and implemented to resolve each respective problem.
The types of information needs which relate to technical considerations
are:
1. Identification and assessment of existing and potential silvicultural
pollution problems
-- Location of planned, ongoing and completed silvicultural
operations which could or are creating pollution problems in
forested and associated watered areas
-- Location and type of silvicultural activities within watersheds
above the polluted stream or stream segments
-- Silvicultural practices and methods of operation that could be or
are contributors to the pollution problem in streams or other
water areas
-- Site factors, such as steepness of slope and erodiblity soils,
associated with these problems and sources
-- Areas and types of ownership on which the practices and
methods of operation take place
-- Variations, if any, in pollution problems associated with the
weather extremes or seasonal scheduling in which the practices
and methods of operation take place
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-- Variations, if any, in pollution problems in relation to the
proximity of activities to receiving waters
-- Sensitivity of the receiving waters and their associated
aquatic environment to changes in pollution loads
2. Identification of feasible means to control pollution
-- Alternative practices which are applicable to the activity and
to the situation in which it occurs, and which promote harmony
between BMP for pollution control and for other appropriate uses
of the land
-- Optimum mix of feasible prevention and reduction or mitigation
practices and operative methods needed to achieve cost-effective
pollution control
-- Appropriate scheduling for BMP implementation
3. Identification and participation of public groups in BMP development
and implementation
-- Interested general public
-- Professional societies, and associations
-- Forest industry and timber and woods operators
-- Other agencies engaged in water quality management planning
-- Federal agencies
-- State forestry agencies
-- State water quality agencies
-- Teaching and /or research institutions
-- Appropriate local governmental units
-- Professionals of related specialties
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The information needs for elements dealing with arrangements required
for effective program implementation will be more clearly defined in other
documents. However, that information might logically include:
-- Adequacy of present programs in preventing pollution from
silvicultural operations
-- Program modifications needed to prevent pollution problems
from arising and maintain production of forest benefits
-- Criteria for utilizing manpower and programs across agency
lines.
Program Checklist
Much of the data needed for water quality management planning already
exist but are scattered through various Federal, State, and local agencies;
professional organizations; research institutions; and private enterprise.
These data must be brought together, interpreted in the proper context,
and synthesized into a system. Following is a checklist to aid in proper
selection, interpretation, and synthesis of these data. This checklist
may be refined at the local level, if necessary.
1. Identification and assessment of pollution problems
Does the planning process include:
-- Use of all logical sources of information? For example, have
federal agencies such as the Forest Service and Bureau of
Land Management; the State Forestry agencies; the forest
industry; the academic community; private land-owners;
State fish and wildlife agencies; and others been contacted
and given an adequate opportunity to provide their own input
into this effort ?
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-- Use of a screening process that identifies forest land in terms of
location, extent, types and spatial distribution?
-- Use of a screening process that identifies and defines existing
or potential pollutant sources on forest land with particialar
attention to the relationship of these pollutant sources
to a water quality segment? This includes
the identification and definition of associated types of forest
uses, conditions in the area which are hazardous to water
quality if care is not taken in silvicultural operations, any
polluted conditions in waters in the area in which these uses
occur, and the related site conditions which may be contri-
buting to these pollution conditions ? Is the information being
interpreted and used at the appropriate degree of detail
for problem assessment and analysis and BMP design?
-- Use of a technique that allows separation of man-caused
sources of pollution from natural causes?
-- Use of an analytical method that recognizes and adequately
considers different time frames and operational methods
associated with the various silvicultural activities?
-- Consider and include procedures that reflect the complexity of
geomorphic processes, natural ecosystems, and wildland
hydrology ?
2. Identification of feasible means to control pollution
Does the planning process
-- Include both pollution prevention and pollution reduction viewpoints
in BMP design ?
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-- Look past the first use of the land, e.g., look at superimposed
or subsequent uses that may occur at the same site?
-- Identify and define the land ownership range by type and size ?
-- Identify and define the economic feasibility of a specific practice,
a range of practices ?
-- Use professional forestry expertise in designing BMP for
each kind of inherent hazard to water quality in relation
to existing and anticipated forest uses ?
-- Consider, in BMP design and location: the variations in land
capability; the size and shape of the area on which the activity
takes place; the type, timing, and intensity of the activity;
the owner characteristics and objectives; and the silvical
characteristics and regeneration requirements ?
-- Utilize information on location of sensitive areas, access
location, anticipated harvest sites, and past abused areas in
developing BMP design criteria?
-- Allow for increased water quality improvement (while
maintaining production) as experience is gained and new
knowledge is applied through refinement of BMP?
-- Allow for sufficient flexibility for professional forestry
judgement in BMP design and implementation?
3. Identification and participation of public groups in BMP development and
implementation
Does the planning process
-- Recognize and establish procedures for continued active
participation of the forestry community?
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-- Coordinate silviculture with other nonpoint pollution control
priorities and with other land, air, and water programs ?
-- Utilize local mechanisms for public participation and public
education ?
While this document is not intended as a guide to the development of
appropriate implementation arrangements, the planning process might
logically include:
-- An analysis of existing institutional capabilities of Federal, State,
or local agencies as they may apply to control pollution generated
by man's activities on forested land
-- Identification and definition of a system to implement BMP, as
quickly and completely as possible, under a combination of
existing regulatory, nonregulatory, and institutional arrangements
-- A strategy for incorporating state-of-the-art advances in knowledge,
to the extent feasible, into institutional arrangements and more
effective BMP mixes
-- Identification of governmental and private sector programs and
institutional arrangements that can address the defined pollution
problem
-- Identification of a specific target date for creation of an effective
program package to solve the pollution problem.
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CHAPTER 2
SILVICULTURE IN RELATION TO WATER QUALITY MANAGEMENT
Silvicultural activities, potential pollutants, and practices to prevent
and reduce pollution are interrelated. This chapter presents and briefly
discusses the types of activities, the types of potential pollutants, and
the types of water pollution control practices (BMP) in silviculture. The
interrelationship and flexibility between these three factors allow forest
managers to successfully integrate water quality goals with their other
management objectives, and therefore contribute substantially to a water
quality management system on the landscape.
Although most silvicultural activities affect only a portion of a general
forest area at any given time, they are usually a part of a cyclical process
designed to yield a continuous supply of wood fiber and wood products.
Certain activities, such as those associated with establishment and removal
of the crop, occur only once during the crop cycle. Depending on the tree
species and the area of the country, a crop cycle may span 10 to 100 years
or more. However, the impact of certain silvicultural activities on the
pollution potential may be heavy during operations and may linger until
the forest has sufficiently regenerated to restore the water-handling capability
of the area to pre-activity levels. Other activities, such as those associated
with protection from fire, disease, and insect, and those associated with
crop improvement, may occur several times within the crop cycle. Thus,
the span of silvicultural activities can increase both the short-term and
long-term pollution potential.
Description of Activities
While all silvicultural activities are interrelated, activities producing
pollutants are associated with (1) access and transport systems (log roads,
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etc.), (2) harvesting, (3) crop regeneration, and (4) intermediate practices
and activities (thinning or fire, insect, and disease control). The amount
and type of pollutants generated by these activities are strongly influenced
by the magnitude and characteristics of climatic events, the physical
characteristics of the area (soils, topography, etc. ), and the characteristics
of the individual operations as they are practiced in a specific area.
The four classes of activities associated with silviculture which
may produce pollutants are:
1. Access Systems
Access to, from, and within forested areas for the purpose of
carrying out silvicultural activities usually is provided through a combi-
nation of resource management roads and trails. In some areas, waterways,
airstrips, and railroads may also be important. The roads, which generally
make up a part of a broader interconnected transportation system serving
many forest uses, including recreation and forest protection, range from
very narrow trails through unsurfaced roads to high-speed paved roads.
How often these access systems are used for silvicultural purposes varies
from intensive to only occasional use over a number of years.
The forest access-road system is often a major contributor of
sediment to the streams in forested areas. These sediment loads may
originate as a result of road construction (including stream crossings),
associated mass soil movement due to slides and slips when built on
unstable terrain, direct erosion from the roads, and indirect erosion
caused by changes in drainage patterns and systems. In addition to sedi-
mentation problems, other pollution problems may be created due to debris
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(organic pollution) resulting from construction and log transport, and from
herbicides used to control the growth of undesirable vegetation on the
right-of-way.
2. Harvesting
Harvesting includes the process of felling the tree, preparing it
by limbing, cutting it into desired lengths, and moving it to a central,
accessible location for transport out of the forested area. The useable
material is moved (skidded or yarded) to a temporary storage site or
"landing" by one of three basic methods: animal or tractor (on skid trails),
groundlead or highlead cable, or various skyline cable methods. Balloons
and helicopters are also being used to a limited extent in some areas.
The animal or tractor and the groundlead or highlead cable methods usually
involve the dragging of at least a part of the material over the ground
surface, whereas the skyline cable, balloon, and helicopter methods generally
lift the material clear of the ground.
The harvesting of wood materials results in partial to complete
removal of forest cover and may compact the soil and remove, add to,
or redistribute the protective cover on the soil surface. Thus, harvesting
methods may affect the erosion process and consequently, the potential
for sediment pollution. In addition to sediment production, harvesting
can create an accumulation of organic debris and slash which may be
washed from the forest floor or otherwise reach the stream, especially
when intense harvest operations are carried out in close proximity to the
water area. Harvesting can also result in thermal pollution due to removal
of the canopy over streams.
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There are three basic systems of harvesting used in the United
States. These are single tree (selection), partial removal, and clearcutting.
Each of these systems results in a different type and degree of pollution -
generating potential because of the differences in associated site disturbance.
The single tree, or selection system, involves annual or periodic removal
of certain trees either singly or in small groups. It is generally adapted
to those species that will reproduce satisfactorily under severe competition
for soil moisture, soil nutrients, and light.
Partial removal is normally seed-tree or shelterwood cutting to c eate
small openings which are seeded naturally and protected by surrounding
trees. In the shelterwood system, the old c op is removed in a series
of partial cuttings, each of which is spaced and timed to provide a natural
source of seed, shade, and shelter for the new crop. The seed-tree cutting
system involves the removal, in one cut, of the mature timber from an
area, except for those trees left as a seed source for natural regeneration.
Clearcutting is a silvicultural system in which the old crop is cleared
over a, considerable area at one time. Reproduction is secured either
artificially by seeding or planting, or naturally by seed distributed from
trees standing outside the area cleared or from trees felled in the cutting
operation.
3. Crop Regeneration
Crop regeneration refers to the re-establishment of a forest cover
on areas from which trees have been removed by some past occurrence,
such as wildfire, timber harvesting, or temporary conversion to some
use other than the growing of trees. When trees have been absent from
the site for a number of years, regeneration must generally be achieved
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through seeding and planting. Regeneration of a harvested area includes
both the natural regenerative process and man's activities in preparing
the site and subsequent planting or seeding. The method of regeneration
is determined largely by environmental and silvical requirements of the
tree species involved, limitations imposed by characteristics of the land,
economic considerations, and the land manager's desire for forest composition.
In some plant communities, natural regeneration under any of the harvesting
systems may also occur by regrowth from roots or stumps.
Preparation, as well as protection, of an area is sometimes needed
for regrowth of a stand. Where site preparation for regrowth is needed,
the major activities may include:
-- Debris removal to reduce fire hazard and allow use of
equipment for subsequent operations;
-- Reduction or removal of brush or shrub cover and
undesirable species of trees; and
-- Cultivation of the soils.
When used indiscriminately for site preparation, fire, chemicals,
and soil-disturbing machinery increase the potential for sediment and other
pollution to occur. The timespan for such pollution to occur is variable
depending upon the climatic factors, the soil productivity and its influence
on rate of plant growth, the species of vegetation planted or seeded, and
the operational schedule. In some areas the timespan may be a single
growing season, while in other areas it may cover several years.
4. Intermediate Practices
Other silvicultural practices relating to thinning of an immature
forest, fertilizer application, and pesticide treatments may be undertaken
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during the crop cycle. The thinning process involves the removal of selected
trees from an immature forest. In essence, this is a type of harvesting which
would tend to create potential sediment-generating conditions if carelessly
carried out. Chemical application of fertilizers and pesticides during
intermediate practices can result in water pollution, if improperly carried
out or adversely affected by an extreme and unexpected natural event.
Disturbances Associated with Silvicultural Activities
Nonchemical forms of pollution that result from silvicultural activities
generally relate to disturbances of the soil and vegetation. The kind and
amount of disturbance is largely dependent on five main factors:
1. Characteristics of the area on which the silvicultural activities are
carried out, i.e., nature of the soils, vegetation, climate, and
topography;
2. The type and character of the activity, e.g., the specific regeneration
system used in carrying out timber harvesting -- selection, shelterwood,
seed-tree, or clearcutting;
3. The method used in carrying out the activity, e. g., for timber har-
vesting -- animal, tractor, high-lead cable, skyline cable, balloon, or
helicopter;
4. The specific features of the activity, e.g., intensity, and size and
shape of the area on which it is applied; and
5. The location of the activity, i. e., its proximity to stream channels
and lake shores.
Timing of the activity is a sixth factor which may be important in some
situations. Where applicable and feasible, the amount of soil disturbance
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may be reduced by logging when the ground is frozen; when it is covered
with snow; or when the ground's soil moisture is relatively low.
Although generalities can be misleading and must be carefully examined
by appropriate professionals for application to local situations, these
generalities are useful in establishing a common framework for examining
alternative solutions to water pollution problems. To illustrate, the relative
impacts of the different categories of harvesting systems based on the
disturbances which can create water pollution problems are generalized
in the following discussion.
Soil and Vegetation Disturbance
It may be necessary to construct additional roads and trails where an
access system is inadequate to serve the particular harvesting system. This
construction activity can result in severe to complete disturbance of soil
and vegetation. The extent of such disturbance can be minimized by fitting
the access routes to the terrain, by minimizing stream crossings, by
using appropriate design criteria, and by using the least soil-disturbing
and soil-impacting equipment and techniques.
1. Selection Cutting Systems
Due to the scattered nature of cutting, the selection systems are
generally not adapted to use of high-lead, skyline, balloon, or helicopter
logging methods. Thus, they usually require an extensive system of roads
and skid trails. Disturbances of the general forest area are usually limited
to soil and undergrowth in the area immediately around the individual trees
or groups of trees harvested, with little deterioration of the soil-holding
network of plant roots. Since selection cutting generally involves the removal
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of only the mature, over-mature, or dead trees; maintenance of a healthy
stand of trees often requires more frequent entry to the harvest area
than other regeneration methods. Further disturbance of the soil, although
relatively small, can occur at fairly short re-entry intervals.
2. Shelterwood Cutting Systems
Several ways in which the shelterwood systems may be applied
include general progressive cutting of trees over the entire harvest area,
and cutting in strips or in groups. Tractor logging is generally adapted
to the system, but where strip or group shelterwood modifications are
used, and wood volumes and terrain are favorable, other logging methods,
such as high-lead cable or skyline cable, may be employed. An extensive
system of roads and skid trials is generally needed where tractor logging
is used. Fewer, more widely spaced roads, may be adequate with the
cable systems.
Since the most important function of the series of partial cutting
is to create ideal site conditions for the germination of natural seed fall,
a certain degree of disturbance to soil and ground cover throughout the
cut area is necessary. Where initial cutting fails to create the proper
seedbed conditions, artificial methods to prepare small seed spots at close
intervals are often used. A minimum of two cuttings is required in the
simplest application of shelterwood cutting. Under intensive management,
more than ten cuttings often are made in the gradual process of simultaneously
freeing the reproduction and removing the mature stand. Often the regeneration
period ranges from 10 to 20 years, but may extend to 60 years. Therefore,
some degree of redisturbance to soil and vegetation can occur at rather
frequent intervals.
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3. Seed -tree Systems
In some classifications, the seed-tree system has been included
under clearcutting systems, since the area is clearcut except for certain
seed trees which ordinarily make up less than 10 percent of the total
volume of wood on the area. Like clearcutting, any one or a combination
of the logging methods may be appropriate, depending upon site conditions,
economics, volume of timber, and many other factors, including proximity
of the activity to the receiving waters. In comparison to selection cutting,
fewer roads and skid trails are needed in seed-tree systems. Severe
disturbance of soil and vegetation may occur over most of the cut-over
area, unless skyline, balloon, or helicopter methods are used.
The amount and degree of disturbance are usually less with high-lead
systems which raise at least a part of the log off the ground than with
tractor logging where all of the material is dragged over the ground.
After the new crop is established, the seed trees usually are removed
in a second cutting. Some redisturbance of soil and vegetation occurs
as these trees are harvested. Both the seed-tree and clearcutting systems
can result in at least a temporary deterioration of the soil-holding network
of tree roots over a relatively large area. This can be a particularly
important consideration in steep terrain and in areas immediately adjacent
to stream channels.
4. Clearcutting Systems
The disturbance of soil and vegetation by clearcutting systems
is similar to that of seed-tree systems. The most important difference is
that all material is cut so that the area is laid bare of trees. In many
of the larger clearcut areas, reforestation involves site preparation for
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artificial reproduction. This involves removing much of the remaining
ground cover and adding further to the disturbance of soil and vegetation.
On those clear cuts where logging is done by methods which lift the harvested
material clear of the ground, and where revegetation occurs naturally without
further site preparation, the overall amount of soil and vegetation disturbance
between ccop removal operations can be less than with systems that require
more frequent entry. Redisturbance does not occur until the reproduction
is ready for thinning.
Natural Drainageway and Stream Channel Disturbance
1. Selection Cutting -
Except for disturbances associated with roads and other means
of access, natural drainageways and stream channels are normally not
affected by selection cutting unless the logs are dragged across the drainage -
way or channel, or unless limbs and other unmerchantable portions of
the tree are allowed to accumulate in the channels.
2., Shelterwood Cutting
The degree of disturbance to natural drainageways by shelterwood1
cutting depends on how the system is applied. Where the system involves
general progressive cutting, the impact is similar to that of selection
cutting. Strip or group shelterwood cutting methods, which involve con-
centrated cutting in small areas, may also result in disturbance by logging
equipment of minor tributary drainageways.
3. Seed-tree cutting
In addition to disturbances associated with road and trail crossings,
disturbance of natural drainageways and stream channels may occur whenever
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II-11
logs are dragged across the land surface. Such disturbance is minimal
where skyline, balloon, or helicopter methods are used. In seed-tree cutting
the danger of woody debris entering drainageways and stream channels
within the cut area is relatively high.
4. Cle arcutting
Disturbances of natural drainageways and stream channels are similar
to those associated with seed-tree cutting. As with the seed-tree system,
the degree of disturbance is inversely proportionate to the amount of
material that is dragged across or through the drainageways and channels.
Potential Pollutants From Activities
The most important pollutants which may be generated by silvicultural
activities are sediments and debris, chemicals, including those in the
form of nutrients and pesticides; and thermal effects. The origin of the
pollutants is generally related to more than one of the activities of the
total silvicultural operation.
1. Sediment
An increase in sediment is the most common form of pollution
resulting from silvicultural activities. The additional sediments usually
result from the accelerated erosion of soils, but may also result from
debris and other organic and inorganic waste. Excessive amounts of sediment
affect stream ecology by smothering bottom organisms through the formation
of bottom blankets. They carry nutrients and pesticides, clog streams
and downstream reservoirs, inhibit reproduction of many important fish
species, and alter stream flow and speed. Suspended sediments interfere
with the photosynthesis process by reducing light penetration.
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11-12
2. Nutrients
Nutrient loss, above the natural level, may occur where fertilizers
are carelessly applied during the course of silvicultural operations. Soluble
nutrients may reach surface or ground water through runoff, seepage,
and/or percolation. Insoluble forms may be absorbed on soil particles
and reach surface water through erosion processes. Nutrients may also
reach surface water by direct washoff of slash, debris, and recently
applied fertilizer. Excessive nutrients can lead to imbalance in the natural
life cycles of water bodies.
3. Pesticides
Pesticides, when applied during forest management activities, may
be insoluble or soluble. Pesticides entering surface or ground Abaters
follow approximately the same pattern as nutrients. Pesticides, carelessly
applied, may result in acute toxicity problems in the water bodies or
insidious toxicity problems throughout the entire food chain, from the
lowest to the highest forms of life.
4. Organic Pollutants
Debris, i. e., slash and other nonmerchantable materials generated
by sLlvicultural activities, may result in organic pollution if an inordinate
amount is placed or washed into streams. This organic material may
reach surface waters through direct dumping, washoff, and leachate from
log storage. The organic material places an oxygen demand on the receiving
waters during decomposition. In addition, these materials may lead
to other problems such as changes in tastes, odors, colors, and excessive
nutrients.
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11-13
5. Thermal Pollutants
Thermal pollution may result from silvicultural activities where
the removal of the canopy cover from stream bodies causes the water
temperature to rise. Temperature is a significant aspect of water quality.
In some cases, it may strongly influence dissolved oxygen concentrations
and bacteria populations in streams. The saturated dissolved oxygen
concentrations in streams is inversely related to temperature.
Best Management Practices
"The term 'Best Management Practices (BMP)' means a practice, or
combination of practices, that is determined by a State (or designated
areawide planning agency) after problem assessment, examination of
alternative practices, and appropriate public participation to be the most
effective, practicable (including technological, economic, and institutional
considerations) means of preventing or reducing the amount of pollution
II
generated by nonpoint sources to a level compatible with water quality goals""
Among the various technical aspects to be considered in BMP design
and selection are:
1. The variability of characteristics on individual source areas in terms
of topography, soils, geology, etc. , and their effect on natural
pollution hazards of the area;
2. The variability in climatic factors which influence both the detachment
and transport processes;
3. The variability in the recovery time of the site as it is influenced by
factors, such as climate, soil productivity and plant species; and
4. The variability in the transport behavior of different pollutants and
in the reaction of the receiving waters to these pollutants.
II [Ref 40 CFR, 130.2(q)].
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11-14
in most cases, this variability will prevent a single BMP from covering
all activities and situations. BMP must be structured with these variations
clearly in mind and with full consideration of the particular water quality
problem to be solved. Further considerations include the practicality of
securing early implementation of appropriate Best Management Practices,
the social and economic costs of implementation, and the benefits (water
quality or otherwise ) to society that will result.
The control measure must be fully integrated into the total management
system for the particular forest area and be feasible not only from a
technical standpoint but also from the financial, legal, and institutional
standpoint. To the extent feasible, soils, nutrients, pesticides, and other
chemicals must be kept on the land area where they perform their intended
function of assisting tree growth and health.
Best Management Practices which can be applied to a silvicultural
operation to prevent or reduce pollution of surface and/or ground waters
can be classified as two general types. These are (1) prevention measures
as part of planning, policy and management, and (2) reduction measures
applied on the land as an integral part of the silvicultural activity. Reduction
and prevention measures are generally described in "Processes, Procedures
and Methods to Control Pollution Resulting from Silvicultural Activities",
EPA 420/9-73-010. More specific information on logging roads for the
Pacific Northwest is contained in "Logging Roads and Protection of Water
Quality", EPA 910/9-75-008, Region X, Environmental Protection Agency.
1. Prevention
Prevention through management decision involves the incorporation
of water quality protection in organizational policy and in the planning, design,
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11-15
and scheduling of silvicultural activities. At this stage, location and design
of logging access roads, intermediate activities, harvesting methods, and
reforestation decisions must be made to prevent or minimize the aggravation
of inherent pollution hazards, for example:
a. Pollution potentials associated with access systems may be greatly
decreased by careful location, design, construction and maintenance of the
roads. Waterways should not be used as roadways or skid trails. Except
in lowlands or swampy areas where their use is unavoidable, wet areas
should be used minimally.
b. Pollution potential generated by harvesting and cultural operations
can usually be minimized by selecting methods and operating schedules
which result in the least disturbance or compaction of the soil, both
initially and over the full span of operation. Careful location and use of
tractor roads and skid trails, particularly when the ground is wet, will
reduce sediment generation. As in the case of roads, skid trails should
not be located in normally wet areas, nor should they utilize stream channels
as part of the route, if a feasible alternative exists. Tractor roads and
skid trails should be carefully located to avoid the concentration of water
on long, steep grades. Careful handling of debris will prevent accumu-
lation which tends to act as dams in streams, and results on breakup,
in high stream velocities causing channel erosion. Early revegetation of
disturbed areas will provide stabilization of the soil, thus minimizing
erosion. Additional techniques, such as provisions for special streamside
management areas, may be useful.
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11-16
2. Reduction
Reduction measures to control erosion and sediment runoff generally
utilize some physical, biological or chemical method or technique. They
modify and reduce the unavoidable disturbances caused by an activity, for
example:
a. Revegetation of cleared areas, mulching of road cuts and fills,
and removal of debris from water courses.
b. Structural measures such as culverts, ditches, berms, rip-rapping,
baffles, drop structures, catch basins and slope stabilization on road sites.
c. Removal of temporary bridges and culverts, removal of temporary
road fills across water courses, and closing and revegetation of temporary roads
and skid trails after completion of harvest and reforestation activities.
Because of the widespread nature of sediment runoff, erosion control
measures must be a principal thrust of the water quality management program
of each management unit. In the areas where nutrients, pesticides, and
other chemicals cause particular problems in surface or ground waters,
further control measures may be necessary. These measures would relate
to the application (timing, method, and amount), utilization, and management of
the fertilizers, pesticides, and fire retardant chemicals. Particular attention
should be taken to keep chemicals away from streams. Care must be exercised
to insure that thermal problems are not created in streams by excessive removal
of shade canopy. Attention to proper forest management, engineering, and
harvesting principles can substantially reduce pollution attributed to silviculture.
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CHAPTER 3
ASSESSMENT, ANALYSIS, & BMP DESIGN
FOR SILVICULTURAL PRACTICES
The methodology described in this guidance is based upon the concept
that:
Nature, in all her diversity, interacts to create different types and
degrees of inherent water pollution hazards. A silvicultural activity
affecting the soil's protective cover or physical conditions, or the
natural drainage pattern, can amplify the inherent hazard and add
pollutants to streams and other watered areas. Pollution control
can be achieved most effectively when the silvicultural activities and
their accompanying specific water pollution control measures are
designed within the constraints and opportunities associated with
the inherent water pollution hazards.
This chapter describes a nonpoint pollution control process consistent with
the BMP approach and the above concept. This process consists of ten
milestones. Milestones 1 through 4 are major components of problem
assessment and analysis. Milestones 5 through 10 list the steps involved
in the development of BMP design criteria as well as the steps leading
to BMP implementation and evaluation. The process is outlined in Figure 1.
The milestones are:
1. Identification and evaluation of interactions among climatic,
physiographic, and biologic characteristics of various landscape
areas within the drainage, and determination of the inherent
pollution hazards (hazard indices) of these areas;
2. Description and evaluation of each silvicultural activity -- where,
when, and how each will be or has been carried out; the conditions
each has or may create(d) on the various landscape areas; the degree
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Ill-2
to which the affected area has recovered since the activity
took place; and the change in hazard index of the affected area;
3. Description of the hydrologic, physical, chemical, and biologic
characteristics of the receiving waters, both past and present;
4. Identification of the degree to which the changes in inherent
pollution hazards, due to conditions created by silvicultural
activities, might contribute or are contributing potential pollutants
to the stream or other watered area;
5. Comparison of past trends and present character of water quality
to water quality goals, and identification and definition of
problems;
6. Development of the BMP design criteria needed to meet water
quality goals, considering the differences in conditions created by
silvicultural activities in relation to the inherent pollution hazard
index of the area;
7. Identification of a range of technically feasible, alternative
silvicultural practices or a mix of practices which meet these
criteria;
8. Screening of the technical alternatives to identify those that
are feasible considering factors such as economics, social
attitudes, and needs;
9. Development of implementation schedules for the selected BMP,
followed by actual implementation under appropriate regulatory or
nonregulatory, and institutional arrangements;
10. Development of a feedback system to ensure the use of the most
effective practical means for pollution control consistent with
water quality goals.
-------
NATURAL CONDITIONS
BIOLOGIC
PHYSIOGRAPHIC
CLIMATIC
PAST & CURRENT
SILVICULTURAL
ACTIVITIES
CONDITION OF
RECEIVING WATERS,
PAST & PRESENT
WATER QUALITY GOALS
ECONOMIC
SOCIAL
INSTITUTIONAL
CONSIDERATIONS
NATURAL POLLUTION
HAZARD INDEX OF
LANDSCAPE UNITS
WITHIN THE TOTAL
PLANNING AREA
UNITS OR PORTION OF
UNITS DRAINING TO
EACH STREAM OR
STREAM SEGMENT
SILVICULTURAL BMP
CONTRIBUTION TO
WATER QUALITY
MANAGEMENT
PROGRAM
i
LANDSCAPE UNITS
AFFECTED AND CONDITIONS
"CREATED BY PAST AND
PRESENT ACTIVITIES
CHANGE IN HAZARD INDEX
DUE TO SILVICULTURAL
ACTIVITIES AS MODIFIED
BY RECOVERY
CORRELATION
NO PROBLEM
YES
IDENTIFICATION AND
ASSESSMENT OF
SUSPECTED PROBLEMS
ACTIVITIES DESIGNED
-WITHIN CONDITIONS
AND HAZARDS
I
NO
DEFINITION AND --*-
ANALYSIS OF PROBLEMS
WITH DEFINITION OF "*
BMP DESIGN CRITERIA
TECHNICAL ALTERNATIVES
WHICH MEET CRITERIA
YES
FEASIBLE BMP
IMPLEMENTATION
NO
ATTAINMENT OF
DESIRED CONDITION I
IN RECEIVING WATERS
FIGURE 1. NONPOINT POLLUTION CONTROL PROCESS FOR SILVICULTURE
SINGER/MALONEY
3-77
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Ill-4
Assessment
An assessment should be made to determine existing and potential
water quality problems. This assessment must include an indemnification
of the types and degree of problems and the sources of pollutants
(both point and nonpoint) contributing to the problem. The assessment
of nonpoint sources of pollutants should include a description of the type
of problem, an identification of the waters affected (by segment or other
appropriate planning area), an evaluation of the seriousness of the effects
on those waters, and an identification of nonpoint sources (by category)
contributing to the problem.
Since the assessment is intended to lead to the implementation of a
practical, effective water quality management program, it must examine
the effects on water quality of past, current, and potential activities.
Determination of Inherent Water Pollution Hazards
The inherent water pollution hazard of an area is most directly associated
with the combined erosion and transport processes -- primarily those
involving water erosion, dry soil creep, mass soil movement, and deposition
of particles. The hazard occurs as a result of the interaction between
many factors, such as geologic materials, soil properties, climatic factors,
shape and slope of the land surface, type and amount of protective cover,
and proximity of the area to receiving waters.
Hazards are generally described in qualitative classes, such as low,
moderate, high, and severe. These classes are expressed as the inherent
water pollution hazard index.
Inherent water pollution hazards play an important role in establishing the
natural hydrologic, physical, chemical, and biological characteristics of
surface waters.
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Ill-5
They also play an important role in determining the degree to which the
different kinds and combinations of silvicultural activities, carried out by man,
affect characteristics of surface water, and result or do not result in pollution.
1. Climate
Climatic variables make up the most important driving force for
generation of nonpoint source pollution since they provide the energy for
both detachment and transport of potential pollutants. However, climatic
variables are the most difficult to assess because they are not fixed in
either time or space. Averages, particularly those based upon short records,
can be very misleading.
Figure 2 illustrates a situation in which the use of average monthly
amount of rainfall alone would have led to erroneous conclusions regarding
the timing of climatic conditions associated with pollution generation. The
figure, based on 30 years of data for the area, shows the greatest amount
of rainfall was in February and March j however, the most intense rains
occurred during June and July which actually was the time that climatic
conditions were most influential in pollution generation. The 30-year average
information only helps us to look for the important data.
The evaluation of climatic variables for pollution control planning and
BMP design should focus on those features which are the most significant
to the pollution-generating process during the time required for the site
to recover to its pre-activity pollution-potential level. For example, in
some cases the significant climatic factor may be the amount, duration,
and intensity of rainfall associated with summer thunder storms or with
general frontal storms which can be expected with a certain frequency.
In other cases, it may be spring snowmelt or spring rains on frozen ground.
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24
22
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S 18
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B 10
u
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TIME OF SIGNIFICANT
CLIMATIC CONDITION
RAINFALL
AMOUNT *
J I
I
J I
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N
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EXAMPLE OF A SITUATION WHERE FAILURE TO EVALUATE RAINFALL INTENSITY
AS WELL AS RAINFALL AMOUNT COULD LEAD TO IMPROPER BMP DESIGN
NOTE: THESE DATA WERE BASED UPON MONTHLY AVERAGES,
1930 - 1960 FOR THE EXAMPLE AREA.
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III-7
2. Physiography
Physiographic features of an area affect the way in which water is
distributed once it falls upon the land. Included among these features are
characteristics of landform, geology, soils, and topography. Some of
these characteristics, particularly those of the geologic materials and soils,
are also key to the surface flow potential of the area. This is true not only
for the natural state but also when the area is impacted by silvicultural
activity. Effective pollution control planning and implementation depends to
a large extent upon proper interpretation of the processes such as detach-
ment, transport, and nutrient cycling.
3. Biology
Biological features, particularly those associated with plant
communities on the land, are important considerations in pollution control
planning, because of their interaction with climatic and physiographic
features in the detachment, transport, and nutrient-eye ling processes.
The specific combinations of plant species within biological communities
are reflected in such features as the form and density of the forest vegetation,
the type and amount of associated ground cover, and the soil-holding
ability of root systems. Many of these features can be modified by silvi-
cultural activities. Therefore, proper interpretation of how and to what
extent biological communities and their modification by man affect the
pollution-gene rating process, is important for development of appropriate
water pollution prevention and reduction practices.
Interpretation and Analysis
Without proper interpretation, raw data make little, if any, positive
contribution to the decision-making process. However, when placed in a
water quality perspective by trained and experienced professionals of the
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Ill-8
appropriate disciplines, these data begin to take on meaning. The relative
hazards to various areas as expressed by different combinations of climatic,
physiographic, and biologic features can be expressed on hazard index maps.
These maps are valuable in determining the most probable source of existing
sediment pollution and evaluating the potential amplifying effect of present
and proposed activities on sediment production.
Timing factors are important considerations in water pollution control.
For example, heavy runoff storms, occurring when streamflows or lake
levels are low, often result in degradation of water quality. The potential
for degradation should influence the timing of scheduled silvicultural activities.
Receiving Waters
The present hydrologic and quality characteristics of receiving waters and
their associated aquatic environment reflect not only the long-term interaction
between the climatic and the variety of natural features of the drainage area,
but also the short-term and long-term effects of man's past and current use of
the watershed and its waters. The relative contribution of nonpoint source
pollutant loads in the water, both natural and man-caused, needs to be placed
in perspective since water quality management planning in silviculture focuses
on the control of man-caused aggravated conditions and their expedient recovery.
The inherent hazard index scheme provides a logical approach for a pre-
liminary assessment of man-caused sources of pollution. More important,
preliminary assessment can be verified or adjusted through field checking,
if deemed necessary. Sensitivity of receiving waters and their associated
aquatic envirionment to changes in pollution loads also needs to be determined
or monitored so that appropriate modification of BMP can be developed
and applied. Of particular importance are those waters that are close to
exceeding water quality requirements. For example, a slight increase in
-------
Ill-9
pollution that only changes the habitat of a stream organism for a short
time may still be sufficient to cause eradication of that organism. A
particular silvicultural practice may contribute only a minute portion to
the total pollution load of a large drainage area, but still cause a devastat-
ingly adverse effect on a headwaters' tributary within that drainage.
Interactions
A wide range of inherent water pollution hazards exists due to the
many combinations of conditions that are associated with climatic, physio-
graphic, and biologic factors and their influence on the receiving waters.
The inherent hazard can be very low or perhaps even nonexistent in areas
of flat terrain, highly stable soils, low-intensity precipitation, and
abundant, rapid-recovering ground cover. At the other extreme are the
high hazard areas which are characterized by steep slopes, highly erodible
soils, high-intensity rainfall, sparse ground cover with slow recovery
time, and drainage into highly sensitive streams.
In some cases, the hazard may be associated with only one critical
condition such as sensitivity of the receiving waters or intensity of rainfall.
More often, the pollution hazard is generated by the simultaneous occurrence
of critical conditions in two or more interacting factors. Many combinations
are possible. An extreme combination, illustrated in Figure 3, shows percent
of total annual rain intensity and duration (energy) and percent of total
annual streamflow in relation to their simultaneous occurrence on an area
with highly erodible soils and steep slopes. This information is presented
in a schematic illustration to the right of the figure.
The planner and the forester must work closely together to define the hazard
index and to assess and analyze the effects of silvicultural activities in relation
to those hazards so that BMP design will be effective and implementable.
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Pollution control management must recognize the presence or absence
of pollution-causing interactions on an area-specific basis as well as
on a time-specific basis. Then, each of man's silvicultural activities
can be designed in the context of the inherent water pollution hazard.
Activity Identification and Evaluation
SLlvicultural activities are often carried out in conjunction with or
in the same general area as activities such as construction, mining, waste
disposal, and agriculture. Therefore, a screening process is necessary to
identify and assess water pollution problems related specifically to silvi-
cultural activities in order to design and monitor silvicultural BMP.
The initial screening should identify drainage areas that have (1) receiving
water segments with nonpoint source related water quality problems
and (2) silvicultural activities. This should be followed by further screening
to identify the type of silvicultural activity(s), the inherent water pollution
hazard (s ) on which the activity occur (s), the condition (s) the silvicultural
activity has created, and the relation of these conditions to the identified
water quality problem. The BMP should be designed to prevent or reduce
potential pollution from silvicultural activities regardless of any other
activities in the area.
To serve as a basis for BMP development, additional technical
information is needed. This may include information about the area and
the silvicultural activities such as an assessment of the methods and equip-
ment used, the specific techniques applied, the timing of the operations,
the characteristics of the area, the time required for an adequate protective
cover to develop naturally, and the proximity of the activity to receiving
waters. Where applicable, subsequent use(s) of the area, such as hunter
-------
Ill-12
use of stabilized skid trails, should also be examined. Since these
subsequent uses may cause more damage than the original use of the
area, they must be considered in BMP development.
Establishing Appropriate BMP Design Criteria
The procedure outlined in the preceding sections provides a context for
(1) objectively evaluating each existing water pollution problem that is
associated with silvicultural activities, and (2) identifying the differences
in pollution-generating conditions created by various silvicultural activities
based upon the inherent pollution hazard of the area and the operational
techniques employed. Planners, foresters and persons from allied disciplines
can use this information and establish jointly appropriate BMP design criteria
for current and future activities.
BMP design criteria should recognize how natural pollution hazards vary
on different areas of land and how the factors which create the hazards interact.
Local persons of appropriate scientific disciplines may be needed to adequately
appraise and interpret this information.
BMP design criteria can be divided into two categories: those that can be
followed in most communities and those that can be carried out only to the
extent feasible in some areas. The kinds of criteria selected should
minimize or prevent potential pollutants generated on the land from reaching
the waters at a critical time, and in amounts which are inconsistent with
water quality goals.
Some examples of BMP design criteria are:
1. Minimize, to the degree feasible through proper scheduling
of operations, the extent of unprotected soil surfaces on
high-hazard areas during periods when heavy rain and/or
heavy surface water runoff is most likely to occur;
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111-13
2. Ensure that the maintenance schedule for the access system
includes emphasis on high-hazard areas and provisions for
adequate water-runoff control, cleaning of culverts, and needed
reinforcement of erosion control measures, immediately
prior to and during periods when heavy rain and/or heavy surface
water runoff normally can be expected;
3. Ensure the establishment of appropriate operational controls
to prevent the creation of pollution-generating conditions, such as
deep wheel tracks in roads, during wet weather when immediate
corrective action is not practical;
4. Ensure that appropriate water pollution control practices for the
optimum dissipation of rainfall and runoff-energy are completed
prior to times of the year when heavy rain and/or heavy surface
water runoff normally can be expected in road or access areas as
well as in harvest areas;
5. Allocate, to the extent feasible, the access elements creating greatest
disturbance to those land areas with the lowest inherent pollution
hazard;
6. Minimize disturbance of vegetation on areas outside the actual area
of access-road construction;
7. Adopt road design standards that minimize the creation of large
road-cut and fill sections;
8. Apply stringent design and construction standards at points where
the access element crosses receiving waters or crosses high-hazard
areas close to receiving waters;
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Ill-14
9. Ensure that heavy equipment is operated only in preplanned locations,
which are carefully selected to minimize the equipment's use on
high-hazard areas;
10. Schedule activities and adopt methods of operation which result in
the least amount of active site disturbance during wet weather;
11. Identify, before field operations begin, streamside management areas
a.nd the specific operating techniques and equipment constraints applicable
to these areas;
12. Ensure that temporary culverts, bridges, or other protective measures
are used where stream bottoms or banks would be otherwise damaged,
and that these protective devices are removed after use;
13. Design the access system to minimize, to the extent feasible, the
number of stream c ossings. Carefully choose the place of crossing to
minimize stream damage, rip-rap and buttress fills for bridge approaches
and assure adequate culverting to accommodate high flows;
14. Explore all possible alternatives before logging across streams, and
where no other feasible alternative exists, find crossing sites that
have low, stable banks; firm stream bottoms; and gentle slopes along
the approaches; and
15. Ensure that all forest chemicals and pesticides are used in accordance
with regulations and manufacturer's direction and that care is taken
to prevent their accidental discharge into stream and other watered
areas.
-------
CHAPTER 4
POLLUTION CONTROL PRACTICES
As previously stated, water pollution control BMP generally involve
a combination of prevention and reduction practices which are built into
the interrelated activities of the access system, harvest system, crop
regeneration methods and other intermediate practices. These prevention
and reduction practices modify some aspect of the interactions among land
capability, each silvicultural activity, the conditions created, the natural
mechanisms affected (e.g., erosion, runoff, etc. ), and the associated
pollutants.
The examples in this chapter will illustrate a few of the many
practices which in various combinations may (1) limit the generation of
conditions that could add materially to the pollution potential, (2) reduce
the unavoidable pollution potential created by man's activities and/or (3)
prevent the transport of unnatural and undesirable material from a disturbed
area to receiving waters. These practices generally fit within the broad
framework shown in Table 1. The reader will undoubtedly be aware of
many more that are applicable to his or her local situation. Due to the
complexity of the interaction among all the variables and among the various
practices themselves, the planner should seek competent advice and
recommendations from appropriate professionals, experienced forest owners,
and forest managers to develop a feasible BMP for the solution of a particular
water quality problem and for the prevention and/or reduction of pollution.
A practice or mix of practices that could be a feasible solution to a potential
pollution problem in one situation, may not be feasible in another, or may
even aggravate the problem. Thus, the feasible, implementable BMP,
must be determined on a site-by-site basis with full consideration of overall
management objectives.
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IV-2
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IV-3
Prevention Practices
Pollution prevention practices should be carefully thought out during the
planning stage rather than relying only on adaptive techniques developed
during the actual silvicultural operation. Thus, these practices can be
applied under a wide variety of management alternatives to meet a number
of objectives.
Most of the activities associated with the harvest system, crop
regeneration, and intermediate practices are areal in nature. For example,
the area affected may vary widely in both size and shape and may occur
almost anywhere on the forested landscape. Generally, these activities
reflect different time frames and operational methods and result in
relatively short periods of actual on-the-ground disturbance followed by
recovery of the site to the previous condition. During the operation and
recovery period there may exist great potential for water quality degradation.
Other types of silvicultural activities create a more permanent type of
disturbance. This is particularly true of those activities associated with
the access system when it requires repeated treatment, such as maintenance
of the road bed, drainage features, and proper sight distance.
Following is a list of the general types of prevention practices. Particular
attention is paid to how these practices relate to water pollution control.
They are:
1. Correlate road and harvest plans to obtain the combination that
will minimize the potential for nonpoint source pollution;
2. Locate access routes to avoid, to the extent possible, high-hazard
areas, such as those known to contain a potential for landslides,
highly erodible soils, and unstable stream channels. This is the
most effective of all practices since the effects of poor location often
-------
IV-4
cannot be overcome through project design or use of reduction
practices;
3. Time construction at stream crossings to minimize direct impact
on the stream;
4. Design roads to minimize large cuts and fills immediately adjacent
to stream channels, i. e., make the road fit the topography;
5. Provide for adequate surface and subsurface water control;
6. Provide for adequate reduction measures where high-hazard areas
cannot be avoided;
7. Surface roads where this practice is consistent with other land-
management objectives and where the natural roadbed is composed
of highly credible material, particularly on those sections of road
immediately adjacent to or crossing stream channels;
8. Schedule clearing, preliminary excavation, and erosion control
work to minimize, to the extent feasible, the area of bare soil
that at any one time is subject to uncontrolled runoff during protracted
periods of normally heavy intense rain and/or intense runoff;
9. Schedule herbicide applications at other than periods of normally
heavy rain or runoff;
10. Locate and lay out timber harvest areas to minimize the intensity
of activities and use on high-hazard areas, particularly those
immediately adjacent to stream channels;
11. Select the proper operational methods and equipment for the specific
site conditions;
12. Schedule activities in both time and space to control the amount of
disturbance in any given watershed at any one time;
-------
IV-5
13. Minimizing use of pesticides and other chemicals and carefully
analyze their need before application;
14. Minimize the use of practices which increase infiltration or
concentration of water in areas where mass soil movement
(landslides) is a hazard; and
15. Preplan operational controls for sensitive areas such as streamside,
including management direction and operational stipulations regarding
the type and method of operation within these areas. Stipulate
operational procedures which could be appropriate within the
streamside management area, such as:
-- Maintain sufficient amount of natural ground cover and density
of trees or other vegetation along streams to protect against
thermal pollution, streambank erosion, and the direct movement
of potential pollutants into the stream channel;
-- Locate landings, skid trails, and tractor roads to avoid paralleling
stream channels for long distances; to minimize the number of
channel crossings; and to avoid dragging logs down existing
drainage channels or creating artificial drainage patterns;
-- Use culverts of sufficient size to accommodate high-flow conditions;
-- Fell trees away from the drainage along perennial and intermittent
water courses; and
-- Inspect periodically stream crossings and drainage systems to
insure the clearing of channels and culverts for maximum discharge
capacity.
The photographs in Figures 4 through 10 show examples where advance
planning has been utilized for pollution prevention.
-------
IV-6
FIGURE 4 - TRACTOR HARVESTING OPERATION
This is a cut-over area on very steep ground with slopes up
to 70 percent, but with inherently stable soils, in an area
of low intensity and well distributed precipitation As a
result of careful planning and advance location and construc-
tion of the road^and tractor trails, logging has been done without
significant erosion or other damage to the watershed
-------
IV-7
FIGURE 5 - CABLE HARVESTING OPERATION
A timber-harvesting operation where terrain features, relative
costs of alternatives and management objectives have made the
use of high-lead cable system advisable and feasible. Note
the fan-shaped pattern created by drawing the logs uphill to
a central point. This pattern disperses runoff over the
slope and reduces potential for erosion. Cable systems are
expensive to implement and are most commonly used where forest
regeneration objectives require clearcutting and when large
volumes of timber are to be harvested on steep terrain where
road building is to be minimized.
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IV-8
FIGURE 7 - PREPLANNED STREAMSIDE MANAGEMENT AREA
The slope at left was heavily cut. Streamside management areas
like the one illustrated, within which only carefully selected
activities may be carried out, help maintain water quality and
preserve favorable conditions for fish, wildlife, and recreation
where these values are important.
FIGURE 7 - WELL LOCATED MAIN ROAD
Well-located main road that is constructed around edge of meadow,
avoids damage to water quality.
-------
IV-9
FIGURE 8 - ROAD CROSSING A MEADOW
Good example of road crossing a meadow with minimum disturbance.
Crossing is located at a narrow point of the meadow and has a metal
culvert (hidden by log at far side) large enough to carry runoff
from local watershed. Note that fill is raised above meadow level,
the fill material having been hauled in, and that no excavation has
been made in the meadow.
FIGURE 9 - LOW USE ROAD
A low use road located and built to conform to the landscape with
minimum scil disturbance. The location and design evidence consid-
eration for the erosion values of the soil types, in this case a
sandy soil, as well as other management objectives.
-------
IV-10
FIGURE 10 - TRACTOR ROAD
Tractor road adjacent to creek. Good location, well above high water
level, with a fringe of streamside vegetation, rolling road surface
to minimize water concentration, and no unnecessary soil disturbance.
All logs from a large area were arch-skidded over this road to a
single prepared crossing just below this spot.
-------
IV-U
Reduction Practices
1. Practices to Reduce the Erosion Potential
Sediment produced by erosion is generally recognized as the greatest
pollutant from nonpoint sources. Erosion of soil by water can take a
variety of forms. On the land surface, erosion may consist of sheet
erosion, rill erosion, and/or gully erosion. In the stream channel, erosion
may consist of streambank erosion and/or channel downcutting. Mass
soil movements may also occur in various forms such as landslides,
mudflows, or downward creep of entire hillsides.
Man alters natural surface erosion primarily by removing, changing, or
adding to the vegetative cover; by physically disturbing the soil; and/or by
changing the way water moves over the land surface. Stream channel erosion
is altered by activities which produce changes in the volume, timing, duration,
and/or velocity of water flowing in the channel, or by activities which disturb the
channel bank or bed. Natural mass soil movements can also be accelerated or
impeded, to some extent, by man's activities, particularly those which affect
debris in stream channels; subsurface water movement; weight on the land
surface; and root systems of trees and other vegetation which help to bind
the mass together. In many forest situations adequate ground cover regenerates
naturally within the first year after disturbance, thus providing surface erosion
control. However, if road cuts are too large, slopes too steep, and soils
highly erodible, even this short time span may be sufficient to create
pollution. Generally, vegetation must be developed as quickly as possible
to prevent erosion. Table 2 lists the principal types of erosion control
practices applicable to silvicultural activities, their general types of application,
and some of their favorable and unfavorable features. The photographs in
Figures 11 through 14 illustrate a few of these reduction practices as they have
been applied to meet specific local conditions and management objectives.
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IV-12
TABLE 2
PRINCIPAL TYPES OF REDUCTION PRACTICES FOR EROSION CONTROL APPLICABLE TO
SILVICULTURAL ACTIVITIES WITH SOME FAVORABLE AND UNFAVORABLE FEATURES
IN TERMS OF WATER POLLUTION CONTROL
Erosion Control
Practice
Seeding or planting
of grasses or other
herbacious vegetation
Seeding or planting
of trees or other
woody vegetation
Dispersal of runoff
concentrated by man's
activities
General Types
of Application
Bare soils or
soils with inade-
quate cover where
tree reproduction
is not desired
(short-lived
forbs, grasses, or
legumes where
tree establishment
is desired).
Not an effective
technique for
controlling pollu-
tion caused by
landslides or other
forms of mass soil
movement.
Bare soil or soils
with inadequate
cover
Tractor roads,
skid trails, and
logging roads
Some Favorable and
Unfavorable Features
Provides a relatively quick
cover which decreases soil
erosion, improves infiltra-
tion capacity of the soil,
and may reduce overland
flow of water. Relatively
inexpensive. Kay require
fertilization for establishment
and growth. Grasses and
other long-lived vegetation
usually add to reforestation
difficulty.
Improves infiltration capacity
of the soil and aids in
reducing overland flow of
water after litter layer of
natural materials develops.
Often takes 5 years or more to
become effective. Can result
in decrease of water yields
under some circumstances.
Moderate initial cost. May
require fertilization for
proper growth and vigor.
Retards surface runoff by
reducing slope length and
area of concentration. Permits
infiltration of water as it is
spread onto stable surfaces.
Can increase soil erosion if
water is directed to unstable
areas where it cannot spread
and infiltrate. May require
installation of energy
dissipators. Moderate initial
cost and some maintenance costs.
-------
TABLE 2-Continued.
IV-13
Erosion Control
Practice
Physical treatment of
the land or soil to
improve infiltration or
detain runoff (contour
trenching, furrowing, etc.)
Debris Removal or
Dispersal
Mulching
General Types
of Application
Areas where soil
moisture or rapid
surface runoff
inhibit adequate
plant establish-
ment and growth
Stream channels
Bare soils or
soils with in-
adequate cover
where steepness
of slope or soil
moisture condi-
tions are critical
Some Favorable and
Unfavorable Features
Retards surface runoff
by reducing slope length
and area of concentration.
Increases infiltration and
improves soil moisture on
treated areas thereby aiding
plant establishment and
growth. Loses effectiveness
and can result in greater
soil loss if these practices
fail. Substantial initial cost
and some maintenance costs.
Reduces concentration of
organic materials. Removal
from stream channels lessens
chance of debris dams and
sediment deposits forming and
subsequent streambank erosion.
May result in damage to stream
banks and stream bottoms if not
carefully done. Must be coordi-
nated with fisheries habitat and
other land management objectives.
Moderate to substantial cost.
Aids in maintaining soil
moisture and reduces the rate
of overland flow, thereby
allowing more water to infiltrate
within the soil capacity. May
have a positive or negative
influence on nutrient addition
depending on physio-chemical
environment. May also result
in a higher BOD load if washed
into receiving waters. On Some
soils, increases need for
nitrogen fertilizers. Moderate
cost.
-------
IV-14
TABLE 2 - Continued.
Erosion Control
Practice
Structural measures
such as debris basins,
sediment ponds, re-
taining walls, water
flow retarding
structures, etc.
General Types
of Application
Stream channels,
areas of mass
earth movement
Chemical treatment of
soil (flocculants or
surficants)
Certain fine tex-
tured soils and/or
soils which are
difficult to wet
Some Favorable and
Unfavorable Features
Retards the movement of
water and associated
pollutants from the land
to receiving waters and/or
within stream channels.
Possibility of some additional
pollution during construction.
Moderate to substantial
installation and maintenance
cost.
Application of flocculants on
certain fine textured soils
causes aggregation of soil
particles which improves
infiltration capacity and aids
in reducing overland flow of
water. Pollution potential of
chemicals vary and in many cases
are unknown. The effectiveness
of some flocculants is inversely
related to clay content.
Application of surficants which
reduce the surface tension at
the water/soil interface have
been used with varying degrees
of effectiveness for improving
initial infiltration rates of
some soils. The pollution
potential of many surficants
is unknown.
-------
IV-15
FIGURE 11 - MULCH ON ROAD FILL
A mulch of forest litter, in this case mostly pine needles,
applied to a depth of two inches to this road fill slope has
provided immediate protection against erosion. The seeds of
trees and shrubs which such litter usually contains will pro-
vide permanent cover. This type of inexpensive treatment is
often appropriate on logging roads where erosion proofing is
required.
-------
IV-16
FIGURE 12 - LOG BRIDGE
All stream crossings should include culverts, bridges or other
measures to allow proper passage of water. This log bridge on
temporary logging road will accommodate high-water flows without
damaging the road or stream channel. Because green, unpeeled logs
were used, this bridge will have a short life. At the end of thf
period of log hauling this structure can be removed without damage
to the channel banks.
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FIGURE 13 - ABANDONED LOGGING ROAD
An abandoned logging road which was planted with clover seed
after water control measures were installed to prevent
accelerated water runoff. Clover was used in this case to
meet multiple management objectives, including improved game
habitat as well as erosion control.
-------
IV-17
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IV-18
2. Nutrient Management Practices
Nitrogen and phosphorus are the primary nutrients that may be affected
by silvicultural activities. If not carefully controlled, additions of plant
residues and fertilizers by man may increase the level of these constituents
above their natural levels in streams within and below forested areas.
Nutrient cycling is an important component of the complex and interrelated
processes which are going on continuously within forest ecosystems. Nutrients
are directly related to the soil-formation process and to soil productivity.
During the cycling process, excess amounts of organics and inorganics may be
moved from the land by direct runoff; by leaching and discharge via ground
water/subsurface systems; and by association with sediment from erosion.
Depending on the site, pollution problems resulting from the use of nitrogen
are significantly different than those resulting from the use of phosphorus.
Practices which reduce direct runoff and/or erosion also are effective in
reducing the transport of excessive amounts of nutrients to receiving waters.
However, in cases where the most important transport mechanism is
leaching and discharge via ground water/subsurface systems, such as
highly porous geologic materials or areas with high water tables, additional
and/or alternative practices will have to be used to achieve the desired level
of control. These alternative practices involve modified use of fertilizers
and methods to dispose of forest residue.
3. Control of Nutrient Pollution from Forest Fertilization
Application of chemical fertilizers to sizeable areas of commercial
forests as a means of stimulating growth of new plantations or established
stands of trees, while still a relatively minor operation, has, in some
areas, expanded rapidly over the past few years. Fertilizers are also
applied to forest lands for a number of other silvicultural purposes such as:
-------
IV-19
-- To increase the production of seed from selected trees within a
forest stand or from genetically selected groups of plants within
a tree seed orchard;
-- To improve color, needle retention, and growth within Christmas
tree plantation;
-- To improve vigor and survival of seedlings;
-- To aid survival and initial growth of individual tree plantings; and
-- To aid establishment and growth of vegetation and road cuts and
fills.
Forest lands differ from agricultural lands in their relative susceptibility
to loss of fertilizer nutrients to surface and ground waters. In most, but
not all cases, nutrients on forest sites are less of a potential pollutant.
This is usually attributed to: (a) the difference in frequence and amount of
application, (b) the difference in soil and site characteristics, (c)the
longevity and growth habits of the plants and the degree and continuity
to which they occupy the site, and (d) the retention, utilization and cycling
of nutrients by the biomass of the forest vegetation.
Nutrient pollution from fertilization on forest lands is controlled by
using techniques which avoid direct application to the surface waters and
immediate riparian zone. Also involved are the elimination of excessive
applications, the selection of proper fertilizer formulation, and the proper
timing and method of application.
The key factors in the selection of the type of fertilizer and the method
of application which are most appropriate for pollution control are local soil
nutrient deficiencies, physical condition of the soil, plant species requirements,
cost factors, weather conditions, access, and topography.
-------
IV-20
4. Control of Nutrient Pollution Through Treatment of Forest Residues
Forest residues accumulate as a result of natural mortality of forest
vegetation and of land-management activities, including silviculture. These
residues represent both negative and positive environmental values and,
to the land-owner or manager, they may be both an impediment arid an
environmental variable that can be manipulated to advantage. Forest residues
play c. complex role in the forest system, acting as a source of soil nutrients,
a fire hazard, an eyesore, a protective cover to the soil, an obstruction
to the movements of man and animals, and a source of food, shade and
shelter for some wildlife species. Forest residues may also be potential
sources of insects, pests, disease, air and water pollution. They also
provide additional fiber and habitats not only for game animals and fish
but also for the microflora and microfauna essential to the forest ecosystem.
Both the geomorphology and the vegetative association of any given location
influence the creation and treatment of forest residues.
Many methods of treating forest residues, particularly residues resulting
from timber harvesting, have been used in various parts of the country.
Generally these methods are designed to increase utilization, lessen fire
hazard, prepare seedbeds, remove obstacles to planting, improve scenic
quality of the area, and rehabilitate stream channels. The chief
treatment has been burning either over an entire cutting area or in selected
locations with or without some effort at concentration of the residue.
Large residue material, such as stumps and portions of cut trees which are
unsuitable for timber, may be turned into other marketable products such
as wood chips. Residue may also be disposed of or changed in physical
form by mechanical means, or it may be left without treatment, subject
only to the natural decomposition processes.
-------
IV-21
Varying environmental conditions and management objectives indicate
different treatments for forest residues. Selection of practices for
treatment of residues resulting from silvicultural activities, in terms
of the prevention and reduction of water pollution, should include the
following considerations.
Burning -The prescribed use of fire to modify a forest stand or to
reduce the volume of forest residue to some desirable level, involves
careful planning and determination of specific weather and fuel conditions to
achieve the desired environmental and management objectives. Thus,
prescribed burning is specifically located, confined in area, carefully
timed, and regulated in intensity. In addition to the water pollution control
measures discussed in this chapter, the air pollution aspects of burning
must also be considered.
Fireline construction and snag felling around the perimeter is a common
practice to confine burning to the prescribed area. On flatter terrain the
fireline is usually built by a bulldozer or a tractor equipped with a blade.
On areas too steep for a tractor, the line may be built by hand. Roads,
interconnected skid trails, and chemical fire retardants may also offer
good means of controlling or marking the desired bounds of fires.
Practices to control water pollution potentials generated by prescribed
burning include:
-- Construction of water diversions on firelines in hilly or steep terrain
to drain the water into areas outside the burn;
-- Removal of residue from natural water-concentration areas prior to
burning (dips in the terrain not normally considered water courses);
-- Provision for an adequate strip of undisturbed surface between the
prescribed burn area and water courses;
-------
IV-22
-- Avoidance, to the extent possible, of intense fires on soils that are
immature, highly erodible, and/or subject to the development of
a "nonwettable" condition; and
-- Avoidance of the use of chemicals over or immediately adjacent
to stream courses.
Piling residues for burning by hand or machine has long been the practice
in some areas. In some cases the residue is bunched in piles; Ln others
it is wlndrowed by a bulldozer into more or less regularly arranged rows.
Many mechanical methods have been used, and some are still being developed,
for example, the use of pits or bins for the burning of forest residue.
Pollution control practices where residue is piled and burned include:
-- Avoiding use of equipment exerting heavy ground pressure when the
soils are wet and subject to compaction;
-- Avoiding location of piles within the normal high-water flowage areas
of natural drainageways and water courses;
-- Placing piled material in rows as nearly as possible on the contour;
-- Keeping the rows fairly short and staggering them so that there
is no continuous opening up and down the slope;
-- Minimizing the amount of soil in the rows or piles by using tractors
that have special "brush" blades with teeth;
-- Avoiding the filling of water concentration areas; and
-- Back-blading on the contour in hilly or steep terrain to remove all
uphill and downhill tractor ruts developed during the piling or
windrowing activity.
Residue Removal and Disposal - This practice is used predominantly
to remove large pieces of residue from cut-over areas. Most residue
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IV-2 3
removal and disposal operations follow regular yarding of merchantable
forest products.
Pollution reduction practices in terms of water quality management would
restrict to the extent feasible under local conditions, the use of equipment
that exerts heavy ground pressure during periods when soils are wet or
when soil compaction potential is great.
Rearranging Residue - If land management objectives can be met, and
if the volume and size are suitable, residue may be rearranged or
mechanically treated and left. Such procedures might be appropriate
when fire is a problem and when the maximum amount of organic material
for soil protection and nutrient source outweighs other considerations.
Rearranging residue includes treatments such as chipping, crushing, lopping
and scattering.
Pollution control practices include:
-- Disposal of material well away from stream courses;
-- Restriction of use, to the extent feasible, of equipment exerting
heavy ground pressure on wet or very moist soils;
-- Dispersion of the material over as wide an area as practical; and
-- Removal of undesirable material from stream channels and dispersion
of that material over the area.
5. Pesticide Practices
Aerial and ground applications of pesticides are used in forest
management to control insects, rodents, diseases, weeds, and undesirable
vegetation of many types. Pesticides are usually applied on a periodic basis,
generally at intervals of several years. In most instances these pesticides
are used only when they are cost-effective, and their benefits often outweigh
environmental impacts.
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IV-24
The most important redistribution mechanism associated with
pesticide pollution is direct transport by runoff. However, the mechanisms
of leaching or subsurface flows may be important in areas of highly porous
geologic materials, permeable soils, or high water tables.
Practices that control erosion and runoff also reduce loss of applied
pesticides. In addition to these practices, a number of other often-used
options exist. These options involve manipulation of the pesticide itself
such as form, timing of application, etc. . These can be used alone or
in conjunction with the erosion and runoff control measures. Table 3
lists the principal types of pesticide-management practices applicable to
silvicultural activities and some of their favorable and unfavorable features.
Practices to control water pollution potentials from pesticide use
include:
-- Strict compliance with sound management of the chemicals
whenever pesticides are used, even if runoff control
measures are not necessary;
-- Use of pesticides in strict accordance with the instructions on their
labels;
-- Storage of the chemicals to minimize the hazard of possible leakage;
-- Prevention of direct application on water surfaces; and
-- Disposal of containers after use in accordance with procedures
approved under the provisions of the Federal Environmental
Pesticide Control Act of 1972, as amended.
6. Control of Thermal Pollution
The most important factor influencing changes in water temperature,
over which the forest manager has some control, is streamside shade.
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IV-25
TABLE 3
PRINCIPAL TYPES OF PESTICIDE PRACTICES APPLICABLE TO
SILVICULTURAL ACTIVITIES AND SOME OF THEIR FAVOR-"
ABLE AND UNFAVORABLE FEATURES IN TERMS OF
WATER POLLUTION CONTROL
Pesticide
Practice
Use of alternative control
measures:
biological controls
using insect and disease-
resistant plant varieties
using mechanical control
methods
Reducing excessive treatment
Managing aerial applications
Optimizing time of day for
pesticide application
Removing and treating infected
plants at a preselected location
Some Favorable and Unfavorable Features
Very successful in a few test cases, can
reduce insecticide and herbicide use
appreciably. Further research and
development needed before widespread
applications are practical.
Can sometimes eliminate need for
insecticide and fungicide. Additional
research and development needed.
Applicable to weed control and brush
control along roads, will reduce need
for chemicals substantially, not
economically feasible for large areas.
Increases possibility of sediment
pollution. Requires adequate access.
Reduces pesticide loss; refined pre-
dictive techniques required.
Can reduce contamination of nontarget
areas and direct application over
streams and water bodies. Requires con-
siderable skill in pesticide formulation,
spray equipment, and aircraft capabilities.
Universally applicable, can reduce
necessary rates of pesticide application.
Minimizes area affected by application.
Usually applicable only when the problem
is extremely localized. Requires adequate
access. High costs.
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IV-2 6
In addition to shade provided by vegetation, water temperatures are also
influenced by topography, surface area and volume of the stream., altitude,
stream gradient, groundwater inflow, and type of stream or channel.
However, by maintaining adequate vegetative cover of such height and
density to adequately shade the stream during periods of maximum
solar radiation, water temperature increases can often be prevented and/or
minimized in order to meet management goals. Intentional reduction
of shade, provided by vegetation, can also be used to increase water
temperature to favor certain aquatic species, where desirable.
If vegetation is not spaced close enough, the stream may not be
effectively shaded even though the vegetation is of sufficient height.
In general, the most efficient shade producers are young, bushy, wide -
crown trees. However, understory vegetation, including many species
of brush (shrubs), generally provide very adequate shade for small streams.
The "state-of-the-art" has not advanced to the point where the amount,
type, location, and width of vegetation that must be left to prevent and/or
minimize increases in water temperature in any particular stream can be
prescribed with certainty. This will vary from site to site depending upon
the many factors previously described. Stream characteristics such as
width, volume of flow, gradient, and stream bed collectively influence the
effect on water temperatures of any given amount of exposure to solar
radiation.
Although there has been significant progress in the development of
techniques for predicting water temperature increases, these techniques
have not been tested sufficiently for general application. Except for those
areas where fully tested prediction techniques are available, local experience
and professional judgement must be applied on a case-by-case basis.
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IV-27
Considerations for Specific Land Areas
For any given location, it is usually necessary to apply various
combinations of practices or to modify specific practices due to specific
site conditions, effectiveness of each of the various practices, overall
management goals, or economic reasons. ,
Specific natural conditions that may be considered on a site-by-site
basis are:
1. Physical and chemical characteristics of soils and geologic
i
materials;
2. Landform and topography;
3. Intensity, duration, form, and frequency of precipitation;
4. Prevailing wind direction and velocity;
5. Current and anticipated runoff quantities, duration, timing,
and velocities;
6. Occurrence and depth of groundwater .
7. Density, gradient, orientation, and characteristics of
drainage ways; and
8. Type and character of vegetation and plant associations.
Characteristics of these variable conditions, singularly and in
combination, influence the mechanisms which control pollutant production and
transport to receiving waters. These characteristics also influence potentials,
hazards, limitations, and suitabilities of various silvicultural activities.
The determination of Best Management Practices in each case must also
consider the extent and scheduling of activities planned, the methods
and kinds of equipment suitable for carrying out the activity, the time and
duration of each activity, the time required for natural recovery of the
area from any adverse impacts of the activity, such as soil compaction and
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IV-2 8
removal of vegetative cover from the ground surface; the specific ecological
or silvicultural requirements of the plant species involved; the economic
practicality and technical feasibility of management alternatives; and the
other management objectives for the area.
Pollution potentials often differ widely within a relatively small
geographic area. Therefore, control practices can be most accurately
prescribed on a site-by-site basis. However, plans can be developed for
a larger area if they allow flexibility in practice selection. Such BMP
selection must correspond to detailed differences in soil types, slope
characteristics, and other natural conditions.
There are a number of equations and formulas which can be used to
assess the relative surface soil-erosion (sheet erosion) potential of an
area, based upon an evaluation of the characteristics of factors such as
rainfall, topography, soil, and vegetation. The potential effects of
alternative management practices on water quality are generally reflected
by changes in the factors which might be modified by the practices. These
could include infiltration capacity of the soil, effective slope length, and
amount of ground cover. Generalized predictive tools for determining
sediment loadings from other sources of sediment, such as gullies, stream
banks, and mass soil movement as well as loadings from other types of
of pollutants, are described in EPA-660/2-76-151, May 1976, "Loading
Functions For Assessment of Water Pollution From Nonpoint Sources. "
Due to the general nature of these estimating procedures, extreme care
must be exercised in applying them to small, site-specific areas. In many
parts of the Nation, local values have been developed through research
and verified in connection with the use of these or similar predictive tools.
Where available, these values usually provide more realistic estimates
than those of the general equations or formulas.
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