EPA-440/3-78-001
U.S. ENVIRONMENTAL PROTECTION AGENCY
Water Planning Division February, 1978
SALINITY DAMAGE
I
NONPOINT SOURCE CONTROL GUIDANCE,
AGRICULTURAL ACTIVITIES
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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20460
February 3, 1978
SUBJECT: Transmittal of Document Entitled "Nonpoint Source Control
Guidance, Agricultural Activities"
FROM : Merna Hurd, Director
Water Planning Divisio
TO : Regional Water Division Directors
208 Coordinators
NPS Coordinators
State and Areawide Water Quality Management Agencies
TECHNICAL GUIDANCE MEMORANDUM - TECH - 44
Purpose
This "Nonpoint Source Control Guidance, Agricultural Activities,"
has been prepared to provide State and areawide WQM agencies and other
concerned groups with assistance in the development and implementation
of programs to control nonpoint sources of pollution resulting from
such activities. It has been deliberately written in a form that is
easy to follow so that the reader does not have to be an expert in the
field to understand what the problems are and some of the solutions
that are available.
Guidance
The agricultural nonpoint source guidance document is the last of an
initial series of documents prepared 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 (WQM) planning agencies in carrying out the provisions of these
regulations." The others involved construction (December, 1976), hydro-
modification (February, 1977), silviculture (March, 1977), and mining
(December, 1977). Prepared in accordance with 40 CFR, Part 131, it
presents technical and management guidance information regarding problem
identification and assessment, information needs and analyses, and Best
Management Practices. Activities discussed include irrigated and non-
irrigated crop production and confined and pastured/grazing animal
production.
Enclosure
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EPA 440/3-78-001
NONPOINT SOURCE CONTROL GUIDANCE
AGRICULTURAL ACTIVITIES
Robert E. Thronson
Environmental Engineer, Nonpoint Sources Branch
U. S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF WATER PLANNING AND STANDARDS
WATER PLANNING DIVISION
WASHINGTON, D. C. 20460
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11
ACKNOWLEDGEMENTS
Draft copies of this document were provided to the organizations
listed below for their review. The Environmental Protection Agency
acknowledges the efforts the group extended in analyzing the material
presented in the document and in submitting constructive comments
and suggestions and expresses its appreciation to them. EPA also
acknowledges the interest shown by other groups that requested and
received copies of the guidance document during its preparation.
U.S. DEPARTMENT OF AGRICULTURE
Soil Conservation Service Agricultural Research Service
Agricultural Stabilization Economic Research Service
and Conservation Service
Extension Service Forest Service
U.S. DEPARTMENT OF THE INTERIOR
Bureau of Indian Affairs Bureau of Land Management
Bureau of Reclamation
ENVIRONMENTAL PROTECTION AGENCY
Planning and Evaluation Water Enforcement
Pesticide Programs Water Program Operations
Solid Waste Monitoring and Technical Support
Air, Land and Water Use Water Supply
Water Planning and Standards Deputy General Counsel
Regional Nonpoint Source Environmental Research Lab
Coordinators (10) Athens, Georgia
Robert S. Kerr - Environmental Research Laboratory
Ada, Oklahoma
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iii
COUNCIL ON ENVIRONMENTAL QUALITY
STATES
California Department of
Food and Agriculture
Iowa State Department of
Agriculture
Kansas State Board of Agriculture
Florida State Department of
Agriculture and Consumer Services
OTHER ORGANIZATIONS
Council for Agricultural
Science and Technology
American Farm Bureau Federation
The Fertilizer Institute
National Association of State
Departments of Agriculture
National Grange
Pesticides Monitor
Environmental Defense Fund, Inc.
American Society of Agronomy
American National Cattleman's Association
National Association of Conservation Districts
National Agricultural Chemicals Association
The Conservation Foundation
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IV
TABLE OF CONTENTS
NONPOINT SOURCE CONTROL GUIDANCE, AGRICULTURAL
ACTIVITIES
ACKNOWLEDGEMENT 11
INTRODUCTION 0-1
CHAPTER 1 - EXISTING PROBLEM IDENTIFICATION AND ASSESSMENT 1-1
Identification of Agriculture Activities and Their Related Pollutants.. .1-1
Crop Production 1-2
Irrigated Crop Production 1-4
Confined Animal Production 1-5
Pastured/Grazing Animal Production 1-7
Assessment of Existing Nonpoint Sources of Pollution from
Agricultural Activities 1-9
Cited References 1-14
Additional References Used 1-15
CHAPTER 2 - INFORMATION NEEDS AND ANALYSES FOR SELECTION
OF BEST MANAGEMENT PRACTICES 2-1
Introduction 2-1
Basic Information Needs 2-2
Precipitation 2-3
Wind Data. 2-4
Characteristics of Soils and Underlying Geologic Materials 2-4
Ground Water Conditions 2-5
Topographic Conditions 2-6
Pesticide Usage 2-6
Fertilizers Usage 2-7
Agricultural Practices 2-8
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Analysis of Data 2-14
Runoff Determination 2-14
Estimating Water-caused Sediment Losses * 2-15
Estimating Wind-caused Sediment Losses 2-16
Ci ted References 2-18
Additional References Used 2-20
CHAPTER 3 - SELECTED BEST MANAGEMENT PRACTICES 3-1
Introduction 3-1
Crop Production 3-2
Erosion and Sediment Control 3-3
Control of Nutrients 3-19
Control of Pesticides 3-22
Irrigated Crop Production 3-25
Sal i ni ty Control 3-26
Controlling Sediment and Other Pollutants 3-39
Excess Ground Water Extractions 3-44
Confined Animal Production 3-45
Control of Outside Runoff 3-48
Onsi te Runoff Control 3-49
Disposal of Wastes In Runoff Water 3-51
Disposal of Liquid, Slurry, or Solid Wastes on Land 3-54
Pastured and Grazing Animal Production 3-55
Ci ted References 3-64
Additional References Used 3-66
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CHAPTER 4 - METHODOLOGY FOR ASSESSMENT OF POTENTIAL AGRICULTURAL
NONPOINT SOURCE POLLUTION PROBLEMS 4-1
Pollutants To Be Considered 4-3
Assessing Potential Sediment Problems 4-4
Runoff Determinations 4-5
Sediment Losses 4-6
Cited References : 4-12
APPENDIX A - ABSTRACTS OF BMP HANDBOOKS A-l
Abstracts A-2
Handbook Sources A-6
APPENDIX B - FEDERAL REGISTER, March 18, 1976 B-l
APPENDIX C - BEST MANAGEMENT PRACTICES
STATEMENT C-l
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0-1
NONPOINT SOURCE CONTROL GUIDANCE
AGRICULTURAL ACTIVITIES
INTRODUCTION
The impact of agriculture on the nation's waters is significant as over
506 million hectares (1,250 million acres) of land are used for agricultural,
grazing and closely related purposes. About 157 million hectares (388 million
acres) are used for crop production. In 1975, 1. 6 billion cubic meters (420
billion gallons) of water per day were withdrawn from surface and ground
sources for use in the United States. Although irrigation uses only 35% of
this total quantity, it consumes over 82% of the total amount of fresh water
consumed in the U. S. (360 million cubic meters, or 96 billion gallons per
day). Consumed water represents that water used and no longer available
because it has been evaporated, transpired, incorporated into crops or
products, consumed by animals or people, and otherwise extracted from
the environment.
The present trends in agriculture involve employing modern techniques
at ever increasing levels of complexity for the use of fertilizers, pesticides,
irrigation systems and confined animal feeding facilities. A natural result of
these trends could be an increased potential for pollution of both ground and
surface waters if control of the nonpoint soures of pollution does not receive
equal emphasis.
Preventing water quality degradation must become a major concern of
the 208 planning agency and the agricultural community. Agricultural activities
discussed in the nonpoint source control guidance document are subdivided
into two main categories: (1) crop production, (2) animal production. Each
activity can be separated further into subcategories if local conditions dictate
the need.
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To a large extent, local climatic events such as precipitation, wind,
and the overland flow of water govern the generation and runoff of pollutants
resulting from agricultural activities. Other natural or other conditions
which have a strong influence include soil and vegetative characteristics,
geologic conditions, and topography. Even in irrigated areas, where supple-
mental water is applied to the ground at a controlled rate, the land is
subject to the same powerful influences of highly variable natural forces.
As a result, the runoff of pollutants from lands affected by agricultural
activities is subject to drastic and often unpredictable variations.
Nonpoint source pollutants resulting from agricultural activities include
sediments, nutrients, pesticides, salts, organic materials, and pathogens.
Sediment resulting from soil erosion is regarded as the greatest pollutant,
by volume, that affects water quality. Agricultural lands, particularly crop-
land, are large contributors of excess sediment in the United States. The
national conservation needs inventory of the Department of Agriculture's
Soil Conservation Service estimated in 1971 that the total sediment yield
from cropland per year was more than 0. 9 billion metric tons (1 billion
tons). Cropland is responsible for over 50% of the total national sediment
yield to inland waterways. Finer-grained portions of this sediment often
carry with them significant quantities of plant nutrients, pesticides, organic
and inorganic matter, pathogens, and other water pollutants.
About 1. 8 billion metric tons (2 billion tons) of livestock wastes are
produced annually. As much as 50% of these wastes may be produced in
confined facilities. While most of these waste materials are confined and
eventually spread on farm acreage, runoff and seepage from these sources
pose a potentially significant pollution hazard.
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Commercial fertilizers consumed during 1976 amount to about 44 million
metric tons (49 million tons) in the United States. About 75% of this quantity
is used by farmers. Some of the nutrients from the fertilizers are transported,
together with naturally occurring nutrient elements, to surface and groundwaters.
Pesticides are designed to be lethal to target organisms, but many are toxic
to nontarget organisms. Four major categories of importance to agriculture
are insecticides, fungicides, herbicides, and rodenticides. Of nearly 454
million kilograms (1 billion pounds) of pesticides applied in the United States
during 1970, about 70% was for farm use. It is anticipated that the use of
of pesticides will greatly increase during the next 20 years.
The threat from pesticides results from their persistence in the aquatic
environment. Fish and other food chain organisms accumulate pesticides and
their metabolites or degradation products. Adverse effects often result in high
biological organisms which have consumed contaminated organisms lower in the
food chain. This phenomenon is termed biological magnification. It appears to
be especially significant with pesticides that have a very low solubility in waters.
Irrigated agricultural activites involve the application of supplemental
water supplies to the land. Salts are introduced by the water and concentrated
by evaportation and transpiration processes. The applied water also leaches
additional salts from the soils in the area and transports them, in return flows,
to downstream areas. About 60% of irrigation waters are lost by evapotrans-
piration. The remainder is returned by surface runoff and by subsurface flow to
surface and groundwaters. These return flows can carry large quantities of
minerals and degrade the water quality of the receiving streams.
Organic nonpoint pollutants from agricultural activites result from animal
wastes, crop residues, and other sources. When these substances reach
a water body, they often exert a high biochemical oxygen demand (BOD).
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Agricultural wastes may be a source of pathogens. When these wastes
come in contact with water, plants, and animals they may transmit disease-
carrying organisms. Losses caused by infectious agents of livestock and
poultry have been substantial.
The disposal of solid wastes is addressed by the Resource Conservation
and Recovery Act (RCRA) of 1976. With the exception of animal wastes
applied to the land as soil conditioners and solid or dissolved materials in
irrigation return flows, any discarded material, including solid, liquid,
semi-solid, or contained gaseous material resulting from agricultural
operations will ultimately be subjected to the authority of RCRA. This
authority has been established to insure proper handling of hazardous wastes
and environmentally sound disposal of all solid wastes.
Important factors to consider in preventing, or minimizing, the generation
or runoff of nonpoint source pollution in the agricultural areas include:
controlling erosion caused by water or wind; optimizing use of the proper
pesticides and fertilizers; effective containment and disposal of animal wastes
on land; and increasing the efficiency of the irrigation delivery systems
and water management methods for pollution control purposes. Measures
for controlling the agricultural nonpoint sources of pollution from agricultural
activities will be discussed in detail in Chapter 3, "Selected Best Management
Practices".
Other sections of this document include:
Chapter 1 - "Existing Problem Identification and Assessment".
Chapter 2 - "Information Needs and Analyses for The Selection
of Best Management Practices".
Chapter 4 - "Methodololgy for Assessment of Potential Agricultural
Nonpoint Source Pollution Problems"
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CHAPTER 1
EXISTING PROBLEM IDENTIFICATION AND ASSESSMENT
Identification of Agricultural Activities
and Their Related Pollutants
Agricultural activities responsible for the production of food and
fiber are viewed as two major categories, (1) crop production and
(2) animal production (Table 1-1). These have been further clarified
as non-irrigated crop production, irrigated crop production, confined
animal production, and pastured/grazing animal production. The water
pollution potential of these activities has increased considerably due
to intensified production requirements.
TABLE 1-1
Agricultural Production Activities and Related Pollutants
Crop Production Animal Production
Pollutants
sediments
nutrients
salts
organics
pesticides
pathogens
Irrigated
o
o
X
o
0
--
Non -irrigated
X
0
--
o
o
--
Pastured/
Confined Grazing
o x
X 0
o
X 0
--
o o
x - Principal problem resulting from activity
o - Secondary problem
-- - Minor problem, if any
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Crop Production:
The pollutants which generally result from non-irrigated crop production
are sediments, nutrients, and pesticides. Organics, such as crop residues
also may cause water quality problems.
Sediments: These materials are defined as mineral or organic matter
in fragment form. Deposited into water bodies, they can cover fish
spawning areas, clog the channels of rivers and coat the bottoms of lakes,
reduce light transmission in water, and increase pesticide and nutrient
loadings through the chemicals and other pollutants they have adsorbed.
As a result, water quality is impaired, navigation hampered, and aquatic
life threatened. The fine-grained fractions of sediment are especially
threatening because of their affinity for association with available pesticides
and nutrients, susceptibility to erosion and transport processes, and
inherent ability to pass through many of the applied erosion and sediment
control measures.
A major factor causing accelerated erosion and the production of
sedimentary materials is the practice of leaving the ground surface devoid
of vegetative cover and exposed to the erosive effects of rain, wind, and
runoff water during a large portion of the year. Such barren, exposed ground
may be the result of a faU plowing operation. A third to one-half of the year
is recognized as the growing season across the major agricultural areas
of this country. In many instances, the ground is left bare the remaining
one-half to two-thirds of the year. Where residue has been left on the
surface it often is inadequate to protect the soils from erosion forces.
Although the emphasis on erosion and sediment problems thus far has
been with respect to water, wind erosion is an increasing threat to arid
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or semi-arid western agricultural lands. Wind-borne sediments are
likely to be deposited in low-lying areas where they can be transported
to nearby water bodies.
Nutrients; Nitrogen, phosphorous, and potassium (N, P, and K) are
the three major plant nutrients. Commercial fertilizers make up the
major portion of the N, P, and K used in crop production. The rest is
supplied through the recycling of animal manures and from natural back-
ground sources (soils^legumes, atmospheric conditions, etc. ). Nutrients
utilized by vegetation are soluble in a soil solution with solubilities
varying with the composition of the materials. As a result, nutrients
may become a threat to water quality if they are applied in excess and
transported, by runoff, from the area of application into water bodies.
High concentrations of some nutrients in water may be toxic to humans or
animals; however, the principal problem caused by nutrients is accelerated
eutrophication in water bodies.
Pesticides: Many pesticides are highly toxic to fish and other aquatic
life and can persist in aquatic environments for long periods of time. They
can be applied from the air, from the surface, or injected into the soils.
Wherever crop management is conducted to maximize production,
there may be a subsequent increase in pest and plant diseases associated
with the crop. Where certain crops are grown year after year in an area
(monoculture), a population of pests and/or plant diseases specific to these
crops may develop resistance to a consistently used pesticide. In these
cases, effective control may be achieved by using heavier doses or more
frequent use of the same pesticide, by alternating pesticides or combinations
of pesticides, rotating crops, or by pesticide-crop rotation combinations.
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Organics: Organic pollutants result from crop residue and other
materials that have been transmitted from the agricultural areas into water
bodies. They can exert a high biochemical oxygen demand (BOD) and
may even deplete the supply of oxygen to kill certain forms of aquatic life.
Irrigated Crop Production
Many of the nonpoint source problems associated with irrigated
crop production are similar to those associated with non-irrigated crop
production discussed previously. The addition of irrigation water increase
the pollution potential of croplands with respect to salts, sediments,
and other pollutants associated with sediments. Special problems related
to salts and sediments are discussed below.
Salts: Excess quantities of mineral salts from irrigation return flows
comprise the principal pollution problem in many of the irrigated river
basins of the West. Irrigation waters applied to croplands must provide
for the evapotranspiration needs of the crop as well as a leaching
fraction to wash salts from the plant root zone. Evapotranspiration
processes result in a net increase in the salt content of the water not
used by the crops. When this water moves into surface or ground waters
it degrades their quality and causes pollution. In time, salts also will
accumulate in the soils and, unless removed by leaching with excess
quantities of applied water, will cause crop reductions or failure. Water
quality and crop production thus are closely interrelated.
Sediments: Sediment losses associated with irrigated crop production
are related to the type of irrigation system used, and the character of
the land under cultivation. Approximately 80% of the irrigated land
in the U. S. , 19 million hectares (48 million acres) receives water by surface
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application methods. Flooding and furrow irrigation involve 30% and
50% of the acreage respectively (Reference No. 1-1).
In furrow irrigation, the crops are planted along the slope of the
land in order to facilitate the movement of water to all parts of the field
under gravity flow. This practice increases the sediment yield from
fields as the flowing water can erode and transport sediment particles.
Sprinkler irrigation systems are used extensively in the mid-western
and western states. Many new areas, not readily amenable to surface
systems, are being developed under sprinkler irrigation methods.
Generally, these lands are more susceptible to erosion, especially
when the vegetative cover is removed. Fortunately, sprinkler systems,
can be designed to apply the rate and quantity of water in accordance with
soils and topographic conditions and to include vegetative and structural
erosion control management practices. This will act to prevent runoff
and the resultant erosion and transport of sediments.
Confined Animal Production
The pollutants most closely associated with confined animal production
facilities are nutrients, organics, sediments, salts, pesticides and
pathogens. They have been the cause of considerable water degradation
in the past and, unless controlled, will continue to cause water quality
problems in the future.
Nutrients: The quantity and type of nutrients found in animal manures
vary significantly with the type of animals confined and the feeding ration
used. Nitrogen and phosphorus are two nutrients readily found in them.
The nitrogen content of manures will vary from . 2% to 1. 8% by weight
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depending upon many variables, including time (Reference No. 1-3). The
phosphorus content, however, does not change appreciably with time.
+
Various forms of the nutrients (NO , NH , PO ) are soluble in
34 4
water and readily move with the flow of water. Nutrients in these
forms represent an immediate pollution potential whereas those tied
to more complex compounds may not. They become available more slowly
and over a longer period of time.
Organics: Organic materials in animal manures vary from rapidly
biodegradable cell masses to slowly biodegradable lignins. During bio-
degradation, nutrients for plants become available, depending upon
the type of organic material and the type of microorganisms assimilating
it. If they reach water bodies, organics can impose an immediate and/or
a long term threat to water quality. The severity of pollution resulting
will depend upon their concentration and the relationship between the organic
materials and the physical character of the receiving waters.
Sediments: Both mineral and organic sedimentary matter are potential
pollutants from confined animal production facilities. Mineral sediments
generally result from the soils within unpaved feedlots whereas animal
manures are the source of the organic materials. Sediments often are
associated with a variety of other pollutants such as nutrients and
pesticides which may cause additional water degradation.
Salts: Saline materials associated with animal manures result from
animal rations used for increasing weight production. Excess salts in
feed rations pass through the animals and remain in the manures.
Where concentrations of manures occur on the land, saline conditions
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can result in the soils. Rainfall or runoff water can leach salts from
both the soils and the manures and cause ground and surface water
degradation.
Pesticides: In confined animal feeding, pesticides are used for control
of insects and other pests. When reaching the soil/manure surface,
pesticide particles associate themselves with the solids and solution
portions of the manure pack to increase their pollution potential.
Pathogens: Pathogens are the cause of many bacterial, mycoplasmal,
spiroplasmal, rickettsial, viral, fungal, and other diseases in animals
and man. These microorganisms can be transported in water and may
or may not persist in the environment depending upon many factors.
In 1967 the World Health Organization estimated that more than 150
diseases were transferable between animal and man. The potential
exists for pathogen contamination of swimming and drinking waters when
animals or their wastes can reach them (Reference No. 1-3).
Pastured/Grazing Animal Production
Animals on pasture or range may pose a threat to water quality
when the land is overstocked or where high concentrations of animals
congregate, such as sources of water, salt, and shade. The full effect
of overgrazing on water quality in nearby water bodies is not definitely
known; however, since it removes protective vegetation from the
ground surface, compacts and damages the soil structure by trampling,
and leaves organic and other potential pollutants as litter on the ground
surface, the potential for water pollution is real. Grazing activities,
particularly overgrazing, must be considered potential generators of
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excess sediments, nutrients, organic materials, and pathogens. When
excess quantities of these materials are transported into water bodies
they will cause pollution.
Sediments: Pasture and range lands generally become a nonpoint
source of pollution when overstocking or continued grazing removes
a high percentage of the vegetative cover and leaves soil surfaces
exposed to the elements. The subsequent erosion and loss of sediments
create the potential for water degradation.
Nutrients: Nutrients from manures and decaying vegetation may
become pollutants, particularly near streams or in low-land lake regions
used for winter pasture where snow melt or runoff can quickly carry
them to the water. The initial buildup of droppings during the spring
of the year have been a suspected cause of water degradation in several
low-land lakes (Reference No. 1-4). Nutrient problems are usually most
critical where animals congregate at water, salt, and shade sources
in the pasture or at the farmstead. Excess nitrates from animal manures
could become a ground water quality problem in localized areas where
animals congregate.
Pathogens: It has been recognized that fecal coliform organisms can
occur immediately downstream from areas where animals tend to concentrate.
Localized contamination of surface water, groundwater, and the soil itself could
result from animals in pastures and perhaps ranges. Although fecal coliform
themselves are not pathogenic they indicate that a pathogen could exist and
possibly flourish. Fecal streptococci may also be a reliable and definitive
measure of human or animal pollution (Reference No. 1-3). Maintaining the
health of the animals is critical and proper management of the herd, its by-
products, and exposed land areas, is essential.
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Assessment of Existing Nonpoint Sources
of Pollution from Agricultural Activities
Each of the agricultural activities discussed in this document are
somewhat similar in that they all can generate many of the same types of
major pollutants sediments, nutrients, pesticides and salts. The magnitude
and extent of each type of pollution from crop production activites and from
animal production facilities, however, are different. They are uniquely
characteristic of the type of activity involved and so may require different
assessment techniques for determining problems and problem areas.
The initial phases of any assessment program to determine existing
nonpoint sources of pollution must involve compilation and evaluation of
all available information that is pertinent to the problem. This type
of information should include water quality analyses; stream-flow records;
pollution reports; sediment-loss studies; and reports or recorded data
on fish kills, eutrophication of lakes, increased ground or surface water
salinities; and reservoir sedimentation surveys. Much of the needed
information can be obtained from local, State, and Federal agencies
such as the Soil Conservation Districts; State Conservation, Fish and
Game, Resource, and Water Quality Control organizations; U. S. Geological
Survey, Bureau of Reclamation, Soil Conservation Service, Agricultural
Stabilization and Conservation Service, Corps of Engineers, Bureau of
Land Management; and others. Many times newspaper articles, reports
in local periodicals, or complaints made by individuals or environmental
groups can be valuable sources of information regarding existing problems.
They may involve both surface or ground water pollution.
Sediment can probably be considered the major pollutant caused by
agricultural activities as it results from both crop and animal production
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activities. As nutrients, pesticides, and other pollutants can become
fixed to the fine-grained sediment particles, in areas where they have
been used, these pollutants should be suspected as problems when excess
sediment losses are occurring.
If excess sediment losses are occurring from a nonpoint source area,
even one where no visible signs of erosion are apparent, sedimentary
deposits should be observable immediately downstream where gradients
are reduced. Sediment in ditches, culverts, or drainageways or on
vegetated waterways indicate excess losses are occurring. Records
or reports by County, State, or Federal road or highway departments
regarding maintenance costs for removing sediment deposits from ditches,
culverts or roadways are important sources of data for assessing nonpoint
source of pollution resulting from agricultural areas. Additional data can
be reports and recorded information on turbidity removal within drinking
water plants required to obtain and maintain water supplies for industries
and municipalities, quantities of sediment dredged from rivers to maintain
their conveyance capacity, and progressively larger deposits of sediments
on land and in water bodies downstream from an area of intensive agriculture.
Sheet erosion by water cannot be readily detected by visual observation.
A loss of 5 tons per acre per year would be only several thousandths of an
inch thick. Where erosion becomes severe, rills and gullies may become
visual on slopes and deposited sediments even more extensive in areas
where water gradients decrease.
In semi-arid areas, sediments eroded by prevailing winds may be
observed as deposits where wind velocities have decreased. Their sources
will be located farther in an upwind direction where visual observations of
erosion may indicate there whereabouts. Excess wind erosion is also
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apparent by blowing dust which reduces visibility and makes highway
driving dangerous. Unless stabilized quickly by some type of vegetation
or other control measure, this windblown sediment will be transported
by runoff into drainageways and create pollution problems.
Excess sediment deposits can be detected in small ponds or lakes
downstream from agricultural source areas where sediment losses are
high. Deltas form at the upstream end of these water bodies as a result
of excess sediment loads carried by streams. Deposits of sediment
also form where a stream that is heavily laden with sediment enters a
larger and slower moving stream.
Many reservoirs are surveyed periodically by Federal or State
agencies to determine sediment deposits accumulating in them. These
reservoir sediment deposition surveys present a particularly important
reservoir of data to determine where soil losses from agricultural
activities are extensive. A report entitled "Summary of Reservoir
Sediment Deposition Surveys Made in the United States" provides infor-
mation on these surveys (Reference No. 1-5). It presents reservoir in-
formation obtained by many agencies and is periodically updated. More
detailed data on each reservoir can be obtained by request from the
supplying agency. The average annual sediment accumulation per square
mile of drainage can be obtained from this document.
Where erosion on agricultural lands becomes severe and runoff water
concentrates, rills and gullies form. When this kind of erosion is noted,
it can be quickly identified as a nonpoint source of pollution. Even if
the locality is a considerable distance from a stream and much of the
sediment is deposited, it is merely a question of time before another
runoff event carries it into a water body. The quantity of sediment
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being eroded from the area can be estimated by determining the length,
width, and depth of the rills or gullies and computing their total volumes.
An estimated "bulking factor" can be assigned to determine the volume
of sediment to be derived from a given volume of in-place soil. This
factor indicates that the material occupies a greater volume after it is
eroded than it does before.
Another method of assessing or estimating pollution sources in an
area where sediment problems seem apparent is to evaluate the soil
conservation program to determine if soil losses affected by agricultural
activities exceed the annual limits of from 2 to 5 tons per acre. These
are the figures set by soil scientists to maintain fertility and productivity
for soils over a period of time and can be considered compatible with
pollution control goals unless proven otherwise. For shallow, or thin
soils, these loss figures have been reduced to as low as one ton per
acre per year. If conservation factors in the soil loss equation such
as the cover and management factor (C) and supporting practices factor
(P) have been improperly installed or maintained, or even not installed
at all, soil losses for the area will exceed the limit and potential pollution
sources and problems are indicated (Reference Nos. 1-6 through 1-8).
If no conservation program exists in an area of high stream sediment
loads, the soil losses, and pollution sources, also can be evaluated
through the use of the USDA's Universal Soil Loss Equation (Reference Nos.
1-7 and 1-8). This equation estimates annual sediment, or soil losses
through the use of rainfall and runoff erosivity indices, soil credibility
factors, slope factors, and cover and management and supporting practice
factors. Since the latter two factors have not been implemented for erosion
control purposes they must be estimated from the percent of ground
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cover or, assumed that they provide no control, and are thus valued at 1.
Values for all of the various factors involved in the soil loss equation
can be obtained from Reference Nos. 1-8 through 1-10; U. S. G. S. topo-
graphic maps, U.S. Weather Bureau, Technical Papers; U. S. D. A. soils
bulletins; and other sources provided at the end of Chapter 2.
The nonpoint sources of pollutants other than sediment are even
more difficult to assess than readily visible sediment. Wastes from
organic materials can show up as debris. Soluble pollutants and materials
which adsorb to fine-grained sediment particles can be identified by
leaching and analyzing samples of fine-grained sediments deposited
in nearby water bodies for suspected materials. Analyzing sediment
samples obtained during reservoir sediment deposition surveys can
be an extremely useful tool for indicating pesticide, nutrient, and other
pollutant losses from an agricultural source areas. Toxic materials
in runoff may be apparent downstream from source areas by fishkills
and evidence of excess nutrients by algal blooms in water bodies.
Salts on lands resulting from irrigation return waters often are
visually apparent, particularly in topographically depressed areas,
as light-colored dessicated deposits of salts. Saline surface water
return flows are concentrated in these areas where the water stands
until evaporated by the sun. If the subsurface water table is close
enough to the ground surface, saline water also may be drawn to the
surface by capillary action in the soils and evaporated to leave salts
on the surface as residue. Sampling and testing of this water
from various depths beneath the ground surface should substantiate
conclusions regarding ground or surface sources of the pollutants.
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1-14
CITED REFERENCES
1-1. U.S. Department of Commerce, Bureau of The Census "1969 Census
of Agriculture, Vol. IV. Irrigation". 1971.
1-2. Loehr, R. C. "Agricultural Waste Management - Problems,
Processes, Approaches" Academic Press. 1974.
1-3. U.S. Environmental Protection Agency, Office of Research and
Monitoring "Pollution Implications of Animal Wastes --A Forward
Oriented Review," 3040 07/68. Reprinted June 1973.
1-4. U.S. Environmental Protection Agency, Office of Research and
Development. R. S. Kerr Environmental Research Laboratory,
Ada, Oklahoma - Personal Communication With R. Douglas Kreis,
Animal Production Research Section.
1-5. U.S. Department of Agriculture, Agricultural Research Service, in
cooperation with Committee on Sedimentation, Water Resources Council
"Summary of Reservoir Sediment Deposition Surveys Made In The
United States Through 1970" Miscellaneous Publication 1266. July, 1973.
1-6. Comptroller General of The United States "To Protect Tomorrow's
Food, Supply, Soil Conservation Needs Priority Attention" Report
to Congress, February 14, 1977.
1-7. U.S. Department of Agriculture, Soil Conservation Service "National
Engineering Handbook, Section 3, Sedimentation, " April 1971.
1-8. "Procedure For Computing Sheet and Rill Erosion on Project
Areas, " Technical Release No. Jl, September 1972.
1-9. "Predicting Rainfall-Erosion Losses From Cropland East
of The Rocky Mountains, Guide for Selection of Practices for Soil
and Water Conservation, " Agricultural Handbook 282, May 1965.
1-10. Wlschmeier, W.H. "Storms and Soil Conservation" Journal of Soil
and Water Conservation, Vol. 17, No. 3, 1962.
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1-15
ADDITIONAL REFERENCES USED
1. U.S Environmental Protection Agency, "Methods and Practices
for Controlling Water Pollution from Agricultural Nonpoint Sources, "
EPA 430/9-73-015, October 1973.
2. - , "Characteristics of Wastes From Southwestern Cattle
Feedlots, " Report on Project #13040 Dem. Jan., 1971.
3. - - - -, "Pollution Implications of Animal Wastes -- A Forward
Oriented Review, " Report on Project #13040, July, 1973.
4. U.S. Environmental Protection Agency and U.S. Department of
Agriculture, "Control of Water Pollution from Cropland. Volume I
A manual for guideline development, " November- 1975.
5. — - -, "Control of Water Pollution from Cropland, Volume II.
An overview, June 1976.
6. U.S. Environmental Protection Agency, "Methods For Identifying
and Evaluating The Nature and Extent of Non-Point Sources of
Pollutants, " EPA 430/9-73-014, October 1973.
7. — - - , "Loading Functions for Assessment of Water Pollution
From Nonpoint Sources, " EPA-600/2-76-151, May 1976.
8. , "Herbicide Runoff From Four Coastal Plain Soil Types, "
EPA-R2-73-266, June, 1973.
9. -, "Herbicide Contamination of Surface Runoff Waters, "
EPA-R2-73-266, June, 1973.
10. American Society of Agricultural Engineers "Reservoir Sedimentation, "
Paper No. 71-726 by McHenry, J. Roger. December, 1971.
11. U.S. Environmental Protection Agency, "Water Quality Management
Problems In Arid Regions, " Report on Programs #13030 DYY,
October 1970.
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1-16
12. -, "Quantification of Pollutants In Agricultural Runoff,
EPA-660/2-74-005. February, 1974.
13. , "Pollution Implications of Animal Wastes -- A Forward
Oriented Review, " 13D40-07/68. June, 1973.
14. Western Farm Life "Eight Good Reasons For Range Rotation"
Reprint, September, 1963.
15. Journal of Forestry, "Effect of Livestock Concentration on
Surface - Soil Porosity Within Shelterbelts. " Reprinted from
Volume 55, No. 7, July, 1957.
16. U.S. Department of Agriculture, Forest Service "Effects of
Cattle Grazing Methods On Ponderosa Pine-Burchgrass Range In
The Pacific Northwest, " Technical Bulletin No. 1531, May, 1976.
17. Virginia Polytechnic Institute and State University "Non-Point
Sources of Water Pollution, " Proceedings of a Southeastern Regional
Conference Conducted May 1 and 2, 1975 at Blacksburg, Virginia.
September, 1975.
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2-1
CHAPTER 2
INFORMATION NEEDS AND ANALYSES FOR THE SELECTION
OF BEST MANAGEMENT PRACTICES
INTRODUCTION
Pollutants resulting from agricultural nonpoint sources of pollution
have been a cause of water quality problems for some time. The
Environmental Protection Agency and the U. S. Departments of Agriculture
and Interior, as well as other Federal organizations and State agencies,
have been concerned for the past several years about the effects of
sediments, nutrients, salts, pesticides, organics, and pathogens within
the rural community. Therefore, much information is available which
can be used for problem analysis and control solutions (See References
and Appendix A).
Information needs relative to nonpoint source control vary with respect
to the state-of-the-art of, (1) the control techniques and methodologies
developed thus far and, (2) the data base upon which these techniques and
methodologies depend. Extension of the state-of-the-art of methodologies
and the associated information is not the primary objective of water quality
management. Rather, implementable water quality management programs
which are always based upon the most current state-of-the-art are the goal.
Since much of the information required in water quality management
planning has already been generated, it needs only to be collected and
evaluated in order to design effective control systems of Best Management
Practices.
Precipitation and runoff water are the principal agents responsible
for the generation and transportation of pollutants from the agricultural
areas of any watershed. During dry seasons in the west, supplemental
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2-2
water applied for irrigation purposes can perform these functions.
Precipitation, whether it falls as rain or snow, is the main source of
all water moving through a drainage basin. The natural topographic
conditions, characteristics of the soils and vegetative coverings occurring
in the basin, and the results of man's changing of these natural characteristics
during his agricultural activities govern how much runoff water results
from a given quantity of precipitation.
Since local climatic events such as rainfall, snowmelt, surface
runoff, and wind, to a large extent, control the loss of pollutants from
an agricultural area, these factors must be considered when developing
effective Best Management Practices. Data are needed regarding the
velocity, rate, and quantity of runoff water, or other waters applied
to the ground surface; physical and chemical characteristics of soils
and underlying geologic materials; length, steepness, and roughness
of slopes; effectiveness of the vegetative crop cover in the area; and
effects of alteration of these factors by the agricultural activities being
conducted. Alterations of the natural drainage system is extremely
important and the drainage area above as well as below the agricultural
area should be evaluated.
Basic Information Needs
In order to select the most appropriate and economical selection of
Best Management Practices, basic information must be gathered which
will outline the physical, climatological, and managerial conditions under
which nonpoint source pollution occurs. Once this information is gathered,
its evaluation should reveal these management practices which have the
greatest potential to reduce or prevent water degradation. A water quality
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2-3
management plan should recognize the agricultural activities being
conducted in an area and the management programs needed at the local
level and recommend management alternatives which will reduce the
pollution potentials.
Precipitation
Data on precipitation can be obtained from several sources. Published
data on daily rainfall measured at standard gages are available principally
from the National Weather Service, Department of Commerce (formerly
the U. S. Weather Bureau) in monthly issues of "Climatological Data".
Other Federal and State agencies or universities publish rainfall data on
an irregular basis, often in special storm reports or research papers.
Unpublished data are available from various Federal and State agencies
as a result of field surveys following unusually large storms. These surveys
some times have obtained, from local people, measurements of rainfall
caught in buckets, bottles, and similar containers. They provide added
detail to rainfall maps developed from standard rain gage data.
To make the information more useful for hydrologic work, the National
Weather Service published analyses of rainfall data in the fifty States,
Puerto Rico, and the Virgin Islands (Reference Nos. 2-1 through 2-4). The
western States also are covered by the National Oceanic and Atmospheric
Administration's Precipitation Atlas 2 (Reference No. 2-5). Methods for
making a more precise analysis of the data is presented in publications
such as the Soil Conservation Service's "National Engineering Handbook,
Section 4 Hydrology", the Bureau of Reclamation's "Design of Small
Dams" and others (Reference Nos. 2-6 and 2-7). They provide essential
information for determining, or estimating, the amount of rainfall to be
be expected in the area; the intensity, duration and seasonal distribution
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2-4
of storms with associated probabilities of occurrence; the antecedent
conditions in the drainage, and other factors.
Wind Data
Sediments blowing off cultivated areas may be a serious problem
in areas where noncohesive soils occur, particularly in arid or semiarid
regions. Data regarding the capacity of the wind to cause erosion, the
prevailing wind directions, and the preponderance of wind erosion forces
in the prevailing directions are presented in U. S. Department of Agriculture
Handbook No. 346 "Wind Erosion Forces in the United States and Their
Use in Predicting Soil Loss", (Reference No. 2-8).
Characteristics of Soils and Underlying Geologic Materials
Evaluation of available soils information is of particular importance
for development of Best Management Practices. It will include such
factors as the texture, structure, permeability, chemical characteristics,
etc. Many of these characteristics are interrelated and all may have an
effect on the generation and movement of pollutants from agricultural
lands. Data on possible groundwater bodies underlying the site are also
essential. The depth to the ground water and its quality and direction
of movement should be determined. It could possibly introduce waters
into the site area to carry pollutants into or from the area to degrade
adjacent supplies.
Information regarding the physical characteristics of soils and/or
underlying geologic materials in site areas can be obtained from soil
survey reports published by the U. S. D. A. , Soil Conservation Service,
in cooperation with other Federal or with State agencies; geologic reports
provided by Federal, State, and local agencies; from documents available
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2-5
from universities or other institutions of higher learning; and from
conservation district offices in counties. This information often
is generalized as it is done on an areawide basis and usually for a
different purpose than pollution control. The level of detail of the
information in such documents varies according to the objectives of
the work but they can be valuable for conducting an analysis of hazards
and potentials and for the development of Best Management Practices.
Specific soils data and other information regarding in-place
characteristics of geologic materials beneath the ground surface can
be obtained from agricultural soils bulletins, prior studies or case
histories of problem areas. Additional, more detailed information
can be derived by sampling the materials at the sites and evaluating
the properties of the materials sampled.
Ground Water Conditions
Subsurface water conditions are of critical importance as the inflow
of poor quality ground water into an area can be the cause of pollution
problems. Movement of surface runoff waters containing pollutants into
an underlying ground water body can also cause pollution. Data needed
for pollution prevention with regard to ground water includes depth to
the water body, direction of movement, whether it occurs under confined
(artesian) or unconfined (water table) conditions, and its natural quality.
Ground water information may be obtained from U. S. Geological Survey
Water-Supply Papers and other technical reports, State water development
agency reports, from local data obtained regarding studies of wells and
the quality of water produced by them in the site area, and other sources.
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2-6
Topographic Conditions
An evaluation of topographic conditions in an area, can be made
from information on existing maps such as the Geological Survey's
topographic maps, the Department of Agriculture's soil maps, and
other maps of this type. More detailed data on topography and conditions
will usually be available from the conservation plans prepared by the
Soil Conservation Service.
The length, steepness, and roughness of slopes are important and
may be determined through actually surveying the site or from interpre-
tation of the published reports discussed above, as well as from the
topographic maps developed by the U. S. Geologic Survey, Army Map
Service, and other sources.
Pesticides Usage
Use of pesticides is restricted by Federal law; and State and local
restrictions also may apply. In order to limit the possibility of pesticides
creating detrimental environmental effects as a result of agricultural
activities, strict adherence to label directions is required. In the past,
aU pesticides were listed in issues of the "EPA Compendium of Registered
"Pesticides", which could be obtained from the Super intend ant of Documents,
U.S. Government Printing Office. This document provided information
on dosages and application rates, tolerances, formulations, use limitations,
and pests controlled. It is now outdated and being replaced by "EPA Index
of Registered Pesticides: Their Limitations and Restrictions, " which is
under preparation by the Office of Pesticides Programs. Pesticide appli-
cation rates should conform to registered label directions and application
equipment cleaned or disposed of properly (Reference Nos. 2-9 through
2-11). Data on pesticide uses also can be obtained from each State's
Cooperative Extension Service.
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2-7
Fertilizers Usage
Plant nutrients such as nitrogen, phosphorus, and potassium, which
are present in fertilizers, often create pollution problems. Many other
chemicals are present in minor quantities in the fertilizers (See Table
2-1). They may have been added to make up for soil nutritional deficiencies
or merely occur as impurities. These minor chemicals are not considered
to represent potential pollution problems.
Nutrient Content
Nitrogen
Anhydrous Ammonia 82% N
Urea 45% N
Ammonium Nitrate 33.5% N
Liquid Nitrogen Solution 28-38% N
Ammonium Sulfate 21% N
Calcium Cyanamide 21% N
Calcium Nitrate 16% N
Sodium Nitrate 16% N
Urea-Formaldehyde 38% N
Phosphorus
Rock Phosphate * 2% P
Normal Superphosphate 9% P
Concentrated Superphosphate 21% P
Phosphoric Acid 23% P
Potassium
Muriate of Potash (KC1) 51% K
Potassium Sulfate (K2SC>4) 43% K
Sulfate of Potash-Magnesia 19% K
Multinutrient
Monoammonium Phosphates 11-16% N, 8-20% P
Diaminunium Phosphates 16-18% N, 20% P
Ammonium Pol>phosuhates 10-15% N, 14-30% P
Potassium Nitrate 13% N. 37% K
^Contains 12 to 14% total phosphorus
Table 2-1 Plant-available Nutrients In Common Fertilizers.
(Reference No. 2-12)
The pollution potential from fertilizers will generally be highest where
greater quantities of materials are applied. The Following Table 2 -2
provides data on the percentage of the acreage of different crops that
are fertilized in the U. S. and the national average quantity applied.
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2-8
Crop
Corn
Cotton
Soybean
Wheat
Acres harvested Percent fertilized
(million) N P
63
13,
52
64
.7
.1
.5
.1
(25.
(5.3
(21.
(25.
8 hectares)
hectares )
2 hectares)
9 hectares)
94
79
22
66
87
58
28
46
103
78
15
46
N
as.
(14.
(2.E
(8.
Pounds /acre
9 Kg /hectares)
3 Kg/hectares)
! Kg /hectares)
4 Kg /hectares)
27
23
18
17
P
(5.0)
(4.2)
(3.3)
(3.1)
Table 2-2 Acres Receiving Fertilizer and Average Fertilizer Quantities
Used For Four Crops in The United States in 1974. (After
Reference No. 2-12)
Fertilizers can be mixed and blended to provide the desired nutrient
content. They may be prepared and applied as solids (granules), powders,
liquids, suspensions, or slurries. If free ammonia is available in a fluid,
it must be injected into soils under pressure.
Many states require that fertilizers sold shall meet specific requirements,
be properly labeled, and be registered with the State. Some permit licensing
of the firm. Information must be provided in the label concerning the
fertilizer net weight, guaranteed analysis, and grade, and the name and
address of registrant. The grade gives the percent of elemental nitrogen
(N), available phosphorus (P O ), and soluble potash (K O).
25 2
Agricultural practices
Information is needed regarding existing agricultural management
practices, and their relation to pollution control, in order to adequately
define and develop Best Management Practices for nonpoint source pollution
control. It should include, where appropriate, such things as the:
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2-9
(1) timing and type of tillage operations conducted and soil and
conservation measures used;
(2) crop rotations;
(3) timing and amount of irrigation water applied;
(4) control runoff from farm areas, feedlots, etc.;
(5) timing, type, and quantity of pesticides and fertilizers used; and
(6) disposal areas for pesticides, petroleum products, toxics, etc.
Management practices information for all phases of agricultural activity
are available from the U. S. Department of Agriculture, particularly it's
local offices and many other State and local agricultural and conservation
organizations. A change in management practices can result in widespread
beneficial effects on water quality (Reference No. 2-13).
Crop production: Tillage operations which involve the turning, or
disturbance of soils for agricultural purposes generate the greatest
potential for erosion by both wind and water. The tillage system that best
fits a farm operation depends on the crops to be grown, soil character-
istics, and local climatic conditions. Tilling on the contour (in a direction
perpendicular to the slope of the land) provides for more water conservation
and erosion protection than tilling parallel to the slope (up and down hill).
It reduces the velocity of runoff flow and increases infiltration.
Stripcropping is used to break the length of the slope into segments
by creating vegetated strips across the natural slope of the land. Grasses
and other close -growing cover crops are used to provide more soil protection
than row crops such as corn and grain sorghum. Crops that leave large
quantities of residue after harvest offer more soil protection than crops
which only have small quantities of residue. Continuous row cropping may
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2-10
deplete the organic matter (the decaying plant and animal residue) in
some soils and thereby decrease water infiltration and increase credibility.
Runoff water control structures and other facilities are important
for proper agricultural management. Diversions are constructed across
the slope to intercept excess runoff and divert it to a stable outlet.
They are generally constructed above cropland fields, gully headcuts,
or other critical areas to reduce the volume of runoff water entering
the problem area. Grassed waterways are natural or constructed outlets
used to safely dispose of runoff from fields, diversions, terraces,
and other conservation measures. Terraces are generally applied to
fields where contouring, stripcropping, and tillage operations do not
offer adequate soil protection. They break the length of the slope into
shorter segments and reduce volume and velocity of runoff water.
Many modern diversion and terrace systems utilize buried pipe rather
than grassed waterways for outlets.
Irrigated Crop Production: The type of irrigation method used
is an important factor when considering development of Best Management
Practices for an area. Surface irrigation methods require uniform slopes
without obstructions, while sprinkler systems are generally free from
land form limitations. Many of the presently-used structural sediment
control measures would disrupt the flow of water in surface applied
systems where their use under sprinkler system management would not.
In the initial design of an irrigation system, the flow of water selected
is to provide the quantity of water required to meet agronomic and
leaching demands. The management of the system, whether surface
or sprinkler type, should result in just meeting these demands as
closely as possible with no excess water applied.
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2-11
The soils and vegetative cover characteristics in each area also play
an important role in determining the design of the irrigation system. The
quantity of water applied to erosive soils or to crops providing little cover
(vegetables, etc. ) will be different than that applied to soils which are not
erosive and to cover crops which provide a maximum of cover and root
stability. The information needs for design include a variety of parameters
which describe the soil water plant relationship under consideration.
These parameters include:
1. Soil characteristics such as moisture holding capacity, cation
exchange capacity, pH, permeability, etc.
2. Crop root zone depth.
3. Plant moisture requirements.
4. Irrigation system efficiencies.
5. Daily evapotranspiration from the crop area.
6. Quality of irrigation water.
The topographic conditions must be known in order to design for
water flows which are relatively non-erosive, based upon crop needs
and soils conditions. Data needed involve principally length and steepness
of slopes and the credibility of the soils.
More detailed descriptions of the information needs and the use of
that information may be obtained from the U. S. Department of Interior,
Bureau of Reclamation (Reference No. 2-14) or the U. S. Department of
Agriculture, Soil Conservation Service (Reference No. 2-15). The methods
described in these references are available in computerized form as
well as chart/curve form. Both of these methods organize the data in
a systematic fashion and estimate the water use requirement on a weekly,
monthly, or seasonal basis.
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2-12
Confined Animal Production: The information needs in planning for
the control of this source include (1) that required for on-lot control
and (2) that required for manure disposal/utilization areas. Information
needed with respect to the location and hydrologic design of confined
animal production facilities must involve a consideration of the following
factors:
Climatic parameters (wind, rainfall)
Characteristics of animal wastes
Soil conditions (for unpaved lots)
Topography
Management scheduling of operations
Location relative to water bodies, both surface and ground waters.
Number of animals involved.
The initial facility design needs hydrologic information to provide for
runoff controls which will prevent water from invading confinement areas
as well as controlling that water which results from precipitation within
these areas. Animal manures removed from the facilities and utilized
in crop production to provide crop nutrients and improve soil tilth may
be a source of pollution if no control measures are provided. Information
needs with respect to this source have been outlined under "fertilizers" in
crop production. Applying manures in amounts consistent with crop
demands is suggested in order to minimize losses of nutrients and the
nonpoint source pollution potential.
The application of animal wastes to the land in an environmentally
sound manner, and to coincide with the agronomic demand, is the thrust
of a recent handbook sponsored by EPA "A Manual For -- Evaluating Land
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2-13
Applications of Livestock and Poultry Residue" (See abstract in Appendix
A). This document presents a method and outlines the information
required to determine manure application rates to agricultural lands.
Salts found in animal manures have been a cause of crop production
losses and increased salinities in soils. In the western States, particularly
semi-arid areas, a consideration of the salt content as well as the
nutritional value of animal wastes must be made prior to applying them
to the land. Information needed with respect to the salts include the
relationship between salinity of the manure and the soil solution as
well as the ability of the crops to tolerate salts.
Pesticides used in confined animal production include those for control
of insects and other pests. They generally become associated with the
manure pack although they may be used in areas adjacent to the feedlot.
Information required for preventing runoff of pesticides will involve
which management and application practices are available for effective
control. Since pesticides often are transported on sediments, information
discussed previously regarding sediment control is also needed.
Pathogen control in feedlot and associated facilities involves runoff
control, dust control, and especially animal hygiene enhancement. Infor-
mation is needed concerning the type of animal and pathogen under con-
sideration, disposition of the wastes, areas being contacted by the
pathogen and their sensitivity, and the pre-treatment conducted.
Pastured and Grazing Animal Production; Sediment and nutrient
problems resulting from pastured animals usually are connected with
overgrazing and concentrating animals around salt, water, and shade
sources. Data needed for control includes the types and characteristics
of the pathogens; their avenues of movement to water bodies or other
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2-14
animals; and topographic, soils, vegetation, and climatic conditions.
Much of the information needed is centered around the habits of various
animals and the growth potential of various pasture and range plants.
Analysis of Data
Erosion by water and the resulting soil losses from an agricultural
area is negligible until runoff actually occurs. The quantity and frequency
of precipitation needed to initiate runoff is a function of the interrelation-
ship of many variables such as the rainfall intensity, temporary surface
storage in the area, physical character of soils or underlying geologic
materials, time since prior precipitation has occurred, location and
percentage of the area protected by vegetation, and steepness and length
of slopes at the site.
Runoff Determination
The combined effect of soils, vegetative cover, man's earth-changing
activities on the amount of rainfall that actually becomes runoff from
an area can be estimated in several ways. Probably the most applicable
is presented in the Soil Conservation Service's "National Engineering
Handbook, Section 4, Hydrology" (Reference No. 2-6). It provides infor-
mation on estimating runoff through the use of Watershed Curve Numbers.
Similar information is presented in this same Agency's "Engineering
Field Manual" (Reference No. 2-15). The curve numbers (CN's) are
hydrologic "soil-cover" complex numbers which indicate their relative
value as direct runoff producers. The higher the number, the greater
the amount of direct runoff to be expected from a storm. Existing
hydrologic data which has already been developed for agricultural con-
servation projects, or for other purposes, in the area can also be used.
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Estimating Water-caused Sediment losses
Losses from specified agricultural land uses may be estimated through
the use of the Universal Soil Loss Equation (USLE). It will provide a long
term average annual soil loss from a land area, only a portion of which
may reach a stream within a specific time period. Nutrients and pesticides
can be associated with these sediments, however, the quantity in association
at any one time varies tremendously with the timing, type, and amount
of nutrients and pesticides applied.
The following brief discussion presents the soil loss equation and
an explanation of the various factors that are involved in a soil loss
determination. More detailed descriptions of the methodology can be
found in Reference Nos. 2-12, 13, 16, and 17.
A = RKLSCP
where A - the estimated average annual soil loss in tons per acre
R = the rainfall and runoff erosivity index (a measure of
the erosive force of specified rainfall)
K = the soil-credibility factor (average soil loss per
acre per unit of R above.
L - the length of land slope (ratio of soil loss of the field
to that from a specific test plot of length 72. 6 feet)
S = the land slope, in percent (ratio of soil loss of the field
to that from a specific test plot with a gradient of 9%)
C = the ground cover and management factor (ratio of soil
loss from the field to that of a field under fallow conditions)
P = the supporting practice factor (ratio of soil loss from the
field with support practices such as contouring, strip-
cropping, or terracing to that with straight-row, up
and down slope farming)
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2-16
Notice that factors R, K, L, and S pertain to the climate, soil, and
topography, and therefore are site-specific. The management factors,
L, C, and P, may be changed by man's activities to reduce sediment
losses. In this manner erosion control management schemes may
be selected based upon a given sediment loss, A. These three factors,
L, C, and P, are man's tools for obtaining an "economically achievable"
sediment control plan.
Sediment losses resulting from the more severe gully erosion result
from changes on the ground which have influenced the characteristics
of surface flow or the forces which resist these flows. Once a gully
channel is established, the concentrated flow will sustain constant erosion.
The channel will widen and headward (upslope) erosion will continue until
manmade changes are initiated to restore the original hydraulic stability.
Detailed information to determine rates of erosion are presented in
Reference No. 2-18.
Estimating Wind-caused Sediment Losses
Wind-blown soils lost from agricultural lands poses serious problems
in the arid or semi-arid areas of sandy soils of the western United
States. These types of soil losses from a field disturbed by agricutural
activities of one kind or another depend upon the surface roughness,
moisture content, and cohesiveness of the soils; quantity, type and
arrangement of the vegetation or crops grown; velocity of the wind;
and on the wind "fetch", or distance across the field that the wind
can move without an obstruction changing its velocity.
Information on effects of soils and residues on wind erosion are
available. Published information on wind forces, however, is limited
and data for design of control practices generally meager. Probably
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the most useful document available for determining wind forces applicable
to the assessment of erosion of field soils and for design of wind-erosion
control practices is the Agricultural Handbook No. 346 (Reference No. 2-8).
Data presented in it include prevailing wind erosion directions, relative
magnitude of erosion forces and their capacity to cause erosion, and
the preponderance of erosion forces in the prevailing directions.
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2-18
CITED REFERENCES
2-1. U.S. Department of Commerce, Environmental Science Services
Administration, U. S. Weather Bureau. "Rainfall Frequency Atlas
of the United States for Durations from 30 minutes to 24 Hours and
Return Periods from 1 to 100 Years". Technical Paper No. 40, 1963.
2-2. "Generalized Estimates of Probable Maximum Precipitation
and Rainfall - Frequency Data for Puerto Rico and Virgin Islands"
Technical Paper No. 42, 1961.
2-3. "Rainfall-Frequency Atlas of the Hawaiian Islands for Areas
to 200 Square Miles, Durations to 24 Hours, and Return Periods
from 1 to 100 Years" Technical Paper No. 43, 1962.
2-4. "Probable Maximum Precipitation and Rainfall - Frequency
Data for Alaska and Areas to 400 Square Miles, Durations to 24 Hours,
and Return Periods from 1 to 100 Years". Technical Paper No. 47, 1963,
2-5. National Oceanic and Atmospheric Administration, National Weather
Service. "Precipitation - Frequency Atlas of Western United States",
Atlas No. 2, V. 1-11, 1973.
2-6. U.S. Department of Agriculture, Soil Conservation Service, "National
Engineering Handbook, Section 4, Hydrology", August 1972.
2-7. U.S. Department of the Interior, Bureau of Reclamation, "Design
of Small Dams", 1974.
2-8. U.S. Department of Agriculture, Agricultural Research Service,
in cooperation with Kansas Agricultural Experiment Station "Wind
Erosion Forces In The United States and Their Use on Predicting
Soil Loss" Agricultural Handbook No. 346, April, 1968.
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2-19
2-9. U.S. Environmental Protection Agency, "Regulations for the Acceptance
of Certain Pesticides and Recommended Procedures for the Disposal
and Storage of Pesticides and Pesticide Containers" Federal Register
Vol. 39, 15236. May 1 , 1974.
2-10. "Certification of Pesticide Applicators" Federal Register,
Vol. 39, No. 197, Part III, October 9, 1974.
2-11. "Pesticide Programs "Registration, Reregistration, and
Classification Procedures" Federal Register Vol. 40, No. 129, Part II,
July 3, 1975.
2-12. U.S. Environmental Protection Agency and Department of Agriculture
"Control of Water Pollution From Cropland - Vol. I, A manual for
guideline development" EPA-600/2-75-026(a), November, 1975.
2-13. "Control of Water Pollution From Cropland - Volume II -
An overview" EPA-600/2-75-026(b), June, 1976.
2-14. U.S. Department of The Interior, Bureau of Reclamation, Engineering
Research Center "The Objective Policy, and Implementation of
Irrigation Management Services" Draft copy - August, 1976i
2-15. U.S. Department of Agriculture, Soil Conservation Service. "Engineering
Field Manual for Conservation Practices - Chapter 15 - Irrigation" 1969.
2-16. U.S. Environmental Protection Agency, "Methods For Identifying and
Evaluating The Nature and Extent of Nonpoint Sources of Pollutants"
EPA-430/9-73-014, October 1973.
2-17. U.S. Department of Agriculture, Agricultural Research Service
"Predicting Rainfall - Erosion Losses From Cropland East of The
Rocky Mountains" Agriculture Handbook No. 282, May, 1965.
2-18. "Soil Conservation Service. "Procedures for Determining
Rates of Land Damage, Land Depreciation and Volume of Sediment
Produced By Gully Erosion" Technical Release No. 32, July 1966.
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2-20
ADDITIONAL REFERENCES USED
1. U.S. Department of Agriculture, Soil Conservation Service.
"Sedimentation" National Engineering Handbook - Section 3,
April, 1977.
2. Comptroller General of The United States "To Protect Tomorrow's
Food Supply, Soil Conservation Needs Priority Attention. Report
To The Congress, February 14, 1977.
3. U.S. Environmental Protection Agency, "Management of Nutrients
on Agricultural Land For Improved Water Quality" Report on Project
No. 13020 DPB, August 1971.
4. — - -. "Cation Transport In Soils and Factors Affecting Soil
Carbonate Solubility. " EPA-R2-73-235. May 1973
5. . "Development of Field Applied DDT" - EPA-660/2-740036,
May, 1974.
6. — - -. "Pesticide Movement From Cropland Into Lake Erie".
EPA-660/2-74-032, April, 1974.
7. — - -. "Use of Soil Parameters For Describing Pesticide Movement
Through Soils, EPA-660/2-75-009, May, 1975.
8. — - -. "Volitilization Losses of Pesticides From Soils".
EPA-660/2-74-054, August, 1974.
9. - . "Losses of Fertilizers and Pesticides from Claypen Soils".
EPA-660/2-74-068, July, 1974.
10. - - - -. "Nitrogen and Phosphorus Losses From Agronomy Plots
In North Alabama", EPA-660/2-74-033, April, 1974.
11. American Society of Agricultural Engineers "Movement of Pesticides
By Runoff and Erosion" Paper No. 70-706. By Harm, C. T. ,
December 8-11, 1970.
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2-21
12. U.S. Department of Agriculture, Forest Service. "Forest-Range
Environmental Study, " Current Information Report No. 10, May 1973.
13. . "Range Ecosystem Research, The Challenge of Change, "
Agriculture Information Bulletin No. 346, September 1970.
14. U.S Environmental Protection Agency. "A Study of the Efficiency
of the Use of Pesticides in Agriculture. " EPA-540/9-75-025, July 1975.
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3-1
CHAPTER 3
SELECTED BEST MANAGEMENT PRACTICES
Introduction
Implementation of Best Management Practices to reduce or prevent
the generation and runoff of nonpoint source pollution caused by farm or
ranch agricultural activities should receive a major emphasis from all
people and organizations involved. Because these management practices
are key factors in reducing the pollution potential of our farms and
ranches, it is necessary to evaluate existing agricultural practices
which have known or suspected potential to pollute and replace them
with BMP's which reduce or eliminate pollution. A preventive approach
to pollution control is emphasized in this guidance document, as a result,
proper planning prior to conducting the activities involved is essential.
To conduct operations and then attempt to control nonpoint source pollution
with a "crises-oriented" approach deserves nothing but skepticism.
Best Management Practices for control of nonpoint source pollution
also have secondary benefits which should be recognized. Many of them
are very closely associated with conservation and the long-term productivity
of the natural resources being utilized soils, nutrients, etc.
Pollution prevention through the use of Best Management Practices
is the main theme presented in this chapter. Some of these practices have
been used extensively for many years by some farmers and ranchers in the
operation of their agricultural programs. The examples illustrated in
this chapter represent a few of the many management practices available,
which will result in control of nonpoint source pollution and provide water
quality benefits.
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3-2
Crop Production
Best Management Practices for the control of sediment from crop
land also include those agricultural practices from which the C (ground
cover and field management) and P (supporting practice) factors were
developed for the Universal Soil Loss Equation. They involve measures
ranging from management of surface and vegetative coverings and tillage
to supporting soil and water conservation practices (See Figure 3-1). As
water and wind action both cause erosion and transport of sediments,
these processes must be considered in the design of control practices.
Figure 3-1 -Contour Farming And Strip Cropping For Controlling
Sediment Loss
Techniques developed and used for preventing the runoff of nutrients,
pesticides, and other substances from an agricultural area generally
involve management to ensure that the materials are applied properly,
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3-3
only optimum dosage is used for target pests, timing of application is
considered in accordance with use and runoff conditions, and disposal
of unused pesticides and containers conducted in an approved manner.
Best Management Practices for agricultural activities must be
developed, designed, and constructed, or provided, in accordance with
local climatic, soils, vegetative, topographic, and other conditions to
be fully effective for nonpoint source pollution control purposes. They
should function independently and cooperatively to protect disturbed soils
or other potential nonpoint sources of pollution from rainfall and runoff
water, reduce the velocity and quantity of runoff, filter out sediments
and other materials being transported, and detain runoff to cause
deposition of sediment particles being transported by water or wind.
Erosion and Sediment Control
The major quantity of sediment results from erosion by water, a
complex process. It is dependent upon natural factors such as climate,
topography, and soil characteristics which, in general, are uncontrollable
by man, as well as the production, tillage practices, and structural con-
servation measures which are subject to management decisions and control.
Many control measures and techniques have been developed for preventing,
or reducingjboth the erosion and transport of sediments from an agricultural
area. They vary from management of surface vegetative coverings and
tillage to "structural" practices, or systems of practices.
Many practices useful for controlling, or preventing,the runoff of nonpoint
sources of pollution from an agricultural site also function to reduce the peak
flows and velocities of the runoff waters. Since stream channel erosion in
downstream areas generally results from increased runoff flows caused
by man's activities, this problem can be alleviated by the application of
Best Management Practices.
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3-4
Surface Protecting Vegetation: Cover crops are grown for soil
conservation purposes, when otherwise
there would be no growing plants or
residues to protect the soil surfaces
from erosion, and to filter out
moving sediments. One example is
winter rye which is seeded shortly
after a corn crop is harvested. Even
though residue left from harvesting the
corn provides some surface protection.
the rye more adequately protects the soil
during the fall, winter, and early spring when
the field would otherwise be subject to erosion
Many cover crops can be left on the soil to
serve as a protective mulch, or
Figure 3-2 - Trees Planted on
Gullied Area
Figure 3-3 - The Same Scene Two
Years Later AfterTrees
and Grass Have Become
Successfully Established
be plowed under for soil improve-
ment. They may be special crops
planted specifically to provide pro-
tection or they may be crops typically
found in the rotation but planted at a
different time. In all cases, use of
cover crops provides better protection
from the erosion effects of rainfall and
runoff than the continuous tilling crops.
Trees, shrubs and grasses may be needej
to handle severe erosion problems; and
in critical areas, conditions may require
conversion of cropland to grass or trees
(See Figure 3-2 and 3-3).
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3-5
Strip cropping can effectively reduce the velocity of runoff water
and provide surface soil protection against water or wind erosion.
It involves the alternate arrangement of strips of close-growing crops
or grasses between strips of tilled row crops (See Figure 3-4). The
grasses and close-growing crops function as sediment filters, buffer
strips, and other water control measures.
Figure 3-4 - Stripcrops Planted At Right Angles To Direction of Prevailing
Winds to Stop Wind Erosion
The rotation of sod-forming grasses and legume crops with row
crops which cause conditions that make the ground highly susceptible
to erosion can be effective for reducing soil and nutrient losses in
farmlands and in maintaining soil structure and tilth. Crop rotation
also provides for both deep and shallow rooted plants which bind soil
masses together to prevent erosion and improves its physical condition.
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3-6
Tillage practices: Tillage which involves the turning, or disturbance
of the soil for agricultural purposes
probably generates the greatest
potential for erosion of soils by both
water and wind (Figures 3-5 and 3-6),
A number of alternative tillage systems,1
developed during the last few years to
reduce e/rosion, are identified under the
following names--minimum tillage,
mulch tillage, and conservation tillage.
Figure 3-5 - Furrows Across The
Slope Still Hold Water
a Day After A 4-inch
Rainfall.
Under some systems, a surface
'•' " ' '-I"1'
configuration is obtained that retains
water to increase infiltration of runoff
Others result in residue being left on
the ground surface from a previous
crop to protect it from wind and
water erosion. (Reference No. 3-1).
Figure 3-6 - Furrows Protecting Field
From Wind Erosion and Collecting
Sediment From Field in Background.
The conservation tillage system that best fits a farm operation must
be developed in accordance with the crop types grown, soil characteristics,
topography, and climate of the area. The following systems, if properly
carried out in accordance with site conditions, can be effective in reducing
erosion and the transport of sediments from a farm area:
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3-7
1. No-tillage (Figure 3-7)-- This system uses a disk, or other
device, to cut through the residue of the previous crop, ahead
of the planter shoe. It leaves a maximum of residue cover to
protect the soil and requires no seedbed preparation prior to
tilling. Increased use of herbicides may be needed, however.
2. Ridge plant -- Planting is done on ridges of plowed soil year after
year, with no seedbed preparation prior to planting. It is a good
practice for reducing erosion in straight-row farming as runoff
from rain must run down the ridge into residue collected in the
furrow. Here, the soil is protected and the sediment entrapped.
3. Till-plant -- A narrow planter shoe opens a seed furrow into
which seed is dropped as equipment clears a strip over an old
row, places loose soil over the seed. Furrows must be oriented
along the contour to reduce erosion.
4. Strip tillage -- A narrow strip is tilled and seed planted in
the same operation. Soil between rows is undisturbed. This is
an applicable technique when minor tillage in row zone is needed.
5. Sweep tillage -- Used to kill early fall or spring weeds in small
grain stubble. The soil is shattered and lifted and the residue is
left on the surface for protection. The shattered soil enhances
infiltration of runoff.
6. Chisel planting -- A seed row is prepared by a narrow-blade chisel,
with a planter immediately behind. Water and wind erosion is
reduced as the surface roughness is increased and crop residue
remains to protect the surface.
7. Listing -- Tillage equipment pushes soils into ridges between rows; and
the seeds are planted into furrows in one total operation.
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3-8
This must be done on the contour to conserve water and prevent
soil losses.
8. Plow plant (Figure 3-8) -- Planting is done directly into plowed
ground without secondary or following tillage. The large clods
that develop restrict surface sealing and provide for increased
infiltration of rainfall and runoff.
9. Wheel-track plant -- Planting is done in the wheel tracks of
tractor or planter. Advantages are similar to that of plow-plant
but not restricted to plowed ground.
10. Subsoiling -- This practice breaks up impervious subsurface "pans"
in soils containing such layers. It increases the infiltration capacity
to reduce runoff.
Figure 3-7 - No Till - Corn Plants Coming Through Wheat Stubble.
-------
-
V
Figure 3-8 • -Plow-planting
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3-10
Timing field operations properly can greatly influence erosion and
sediment losses from farm lands. Plowing or other soil disturbing
activity should be minimized during times of great rainfall erosivity.
This requires an understanding of times of the year when the erosion
potential is greatest, types of crops useful during this time, and
characteristics of soil materials subject to erosion.
Performing tillage operations on the contour, normal to the slope
of the land, provides much more protection from water erosion than
tilling parallel to the slope. Furrows can collect and hold large quantities
of water during rainstorms and reduce the runoff velocity, thereby
increasing infiltration and reducing erosion. Contour tilling practiced
on gentle slopes, or in combination with stripcropping or terracing
on moderate slopes, can effectively reduce erosion.
Structural Conservation Measures: Eliminating surface runoff will
largely prevent sediment losses. Sediment will be generated by rainfall,
and other activities but transportation of particles will not occur. Use
of vegetative coverings and tillage practices will do much to control
the runoff but additional measures are required in many cases to reduce
its quantity and velocity. They are termed structural support practices
and are classified as P factors in the soil loss equation. Included under
the structural classification are terraces, grassed waterways and outlets,
diversions, grade stabilization facilities, and water retention structures.
They function to reduce the gradient of slopes or water courses through
which runoff flows, decrease the velocity of running water, trap sediment,
and reduce the peak runoff flow.
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3-11
Additional guidance on the design, construction, and maintenance
of structural conservation measures can be obtained from the Engineering
Field Manual of the Soil Conservation Service (Reference No. 3-2) and
from State Conservation agencies, as well as, from Local Soil Conser-
vation Districts. Consulting agricultural engineering firms can also
provide guidance on control measures.
1. Terraces - Terraces consist of earth embankments, or ridges
and channels which are constructed across the slope of the land
for the purpose of reducing the slope length and intercepting the
flow of surface runoff (See Figures 3-9 and 3-10). They are con-
structed with a level channel and ridge in areas of low rainfall and
pervious soils, to store water and provide infiltration. On less
pervious soils, and where rainfall is greater, they may be graded
to an outlet area and function as a diversion structure. For design,
detailed consideration must be made of the rainfall and runoff
quantities to be expected within particular time periods, soil
characteristics, slope steepness, and type of cropping system used.
Figure 9 - Sketch of gradient terraces with grassed waterway outlet
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3-12
Terraces are designed to reduce erosion by reducing slope
lengths and promoting infiltration of runoff water. Discharge
'of surface water from a terrace must be conducted to a stable
area or to a grassed waterway which will transmit it to a
stable area at nonerosive velocities. Subsurface drains often are
used to release outflow from terraces.
Terrace Ridge
(of fill)
2nd Contributing Area
Figure 3-10 - Sketch of Level Terraces, With Cross Section
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3-13
2. Grassed Waterways - These waterways are basic conservation
measures and are being used for reducing erosion in farmlands.
Consisting of natural, or constructed channels, protected with
erosion-resistant grasses or other vegetation, they provide for
the safe disposal of runoff water from terraces, diversions,
and other structural measures (See Figure No. 3-11). Waterways
subject to prolonged water flows may require additional structural
controls such as grade control structures, provision of non-
erosive center sections, and the like.
Figure 3-11 - Grassed Waterway With Grass Flattened After A
Very Heavy Runoff Period
They must be constructed in advance of any structures that
discharge into them and must be fully vegetated before receiving
runoff flows. If possible, a natural channel should be used for
a waterway, if vegetated sufficiently.
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3-14
3. Diversions - Diversions are channels which are constructed,
with a ridge formed of earth embankment on their lower sides,
across a slope (See Figure 3-12). They are graded to discharge
into grassed waterways or other erosion resistant outlets and
discharge areas. Their principal uses for erosion and sediment
control include protecting farmlands from excess runoff and
sediment deposition, 'reducing the effective length of slopes to
decrease runoff velocities, diverting water away from eroding
areas where it is concentrating or into sediment detention structures,
and providing support to other structural conservation practices
in runoff control.
Figure 3-12 - Diversions Spreading Water to Reduce Gullying
In the location and design of a diversion, consideration should be
made regarding expected quantities and peaks of runoff, the slope
steepness and length, soil characteristics, and the uses of the land
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3-15
above the structure. Areas upslope from diversions should have
erosion and sediment control practices applied to prevent excess
sediment from accumulating in diversion channels and restricting
their capacity to transmit water.
4. Grade control structures - These structures prevent erosion
and grade changes in drainage channels and control the upslope
migration of gullys. They are usually installed after a problem
has been initiated and so must be considered remedial rather
than preventive measures.
Grade stabilization structures are located in areas where runoff has
been concentrated and is erosive, so any portion subject to the runoff
must be made of highly resistant materials such as wood, rock,
concrete, wire mesh, brush, steel, etc. (See Figure 3-13). They
reduce the velocity of flow in erodible channels to reduce erosion
and they provide materials or structures that can withstand the
higher erosive velocities.
Figure 3-13 - Gully Controlled by Small Dams Until Vegetation Can Be
Established.
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3-16
5. Water and sediment detention facilities - In addition to trapping
and detaining sediment eroded from the drainage area above,
these multipurpose facilities can store water for support of fish
production, animal watering, and recreational purposes. They
can be created by the construction of an embankment across
a water course or by excavating a required storage volume (See
Figure 3-14). The latter type generally has limited storage capacity.
Figure 3-14 - Water Retention Structure Traps Sediment Eroded From
Drainage Area Where Terraces, Contour Farming, and
Grade Stabilization Structures Have Been Applied.
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3-17
For effective sediment detention, the detention time must be long
enough for sediment particles to settle to the bottom and be trapped.
If material is fine-grained, such as clay, few farm reservoirs
will be large enough to provide sufficient detention time. Reservoirs
should also be designed to prevent the direct movement of sediment-
laden currents from the head of reservoir to outlet.
Wind erosion occurs mainly in arid to semi-arid areas where
temperatures, and thus evaporation rates, are high; distances are great
enough, without obstructions, for winds to reach erosive velocities; and
soils are loose with individual grains easily separable.
Good farming practices, such as maintaining an adequate vegetative
covering, are important for preventing wind erosion. Minimizing tillage
so that soils consist of stable and cohesive clods rather than small granular
masses also is a useful technique. Clods, or soil aggregates, are broken
down by tillage, weathering, abrasion, and animal or implement traffic. In
areas where crops such as cotton or peanuts are grown on sandy soils, the
seeding of rye in the growing crop a few weeks prior to the harvest, or just
following the harvest, will protect the soil during the winter and early spring.
Any operation or activity which increases the roughness of the ground
surface is a wind-control measure. It can consist of leaving vegetative
matter on the surface, mixing residue in the soil, or by providing ridges
and furrows through tilling operations (See Figure 3-6 and 3-15). Deep tillage
of sandy soils to bring to the surface underlying more clayey soils which form
clods also help reduce wind erosion. Stabilizing the soil surface is critical.
Surface residues are highly effective in reducing both wind and water erosion.
Reducing the effective width or length of fields in the direction of prevailing
winds is another very important wind erosion and sediment transport control
-------
3-18
practice. This can be done by strip cropping, alternating strips of
crops that are highly resistant to wind erosion with strips of crops
that are more susceptible. Strips must be oriented perpendicular to
the wind direction to be effective. Installation of wind barriers consisting
of trees, bushes, fences, rock walls, etc., can also be used to reduce
the length of the field and so reduce the distance over which wind
can blow to increase its velocity. Barriers act to cause deposition
of sediment as well as reduce erosion. The effectiveness of wind
barriers depends on the geometric configuration and porosity of the
barrier, as well as, the wind direction and velocity.
Figure 3-15 - Tillage Operation to Cut Roots of Weeds, Loosen The Soil,
and Mix Organic Residues Into the Surface Soils to
Control Wind Erosion
'
Information regarding wind erosion forces for use in developing
BMP's for wind erosion control is available in the U. S. D. A., Agricultural
Handbook No. 346 entitled "Wind Erosion Forces In The United States and
Their Use In Predicting Soil Loss" (Reference No. 3-3), Th*e information
presented can be used for design and orientation of control measures.
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3-19
Control of Nutrients
Best Management Practices with respect to nutrients applied for
agricultural purposes must reflect the timing, type, and optimal quantity
of nutrients applied, based upon soil tests and the agronomic demand
(See Figure 3-16). The Cooperative Extension Service provides information
and instructions for sampling fields for chemical soil testing. In most
states, the Cooperative Extension Service and commercial (private)
laboratories will conduct soil tests and recommend nutrient additions
needed. In some states (two at present), all public soil testing is performed
by commercial laboratories. Public testing laboratories are operated by
universities, experiment stations, Cooperative Extension Services, and
State Departments of Agriculture.
FIELD INFORMATION
ACIES PLOW LAST VIMS CHOP
(Inch..) YIELD
LAST LIMID
VIS. AGO
I/A
HOCK PMOS.
Y«S.
AGO
IMIGATID
NIWLV
UNO
FUmiZER APHICO LAST YEA*
(LU./A)
N
P,05
K,0
SOIL TEST INFORMATION
LABORATORY ANALYSIS
PholeMi. Organic NaunoliiaMo IXCHANGlA.Li (LbVAl
LB*. At ",. IMC/100 CMS) Calcium Maanviiwrn
Polonium
CSC
MI/100 CMS} 4
P.r C.nt BOM Solurc
h Colcium
% Mogn.iium
lion
% Polonium
DESIRED SOIL TEST LEVELS
Mtoiphou
(LbVAl
151-
E«chono»obl« ILbvA)
Calcium
Mogn.iiui
* Polonium
SUGGESTED SOIL TREATMENTS-POUNDS PER ACRE
BASIC 1
LIME!
•Hl.criv.
N«bnaliiin0
Matei Jal
IENM)
TONE
"fff.t.lv.
Mogr»lium
IEM)
REATMENTS
PHOSPHORUS • POTASSIUM
INITIAL HJILO-UP
(Follow wild Annual Plan A)
Phaipharin
.0=1, |OR
P]0j
Proc.lMd
Pj05
Potoitium
HjO
ANNUAL TREATMENTS
CROPPING PUN
YIA«
1
2
3
4
CHOP
CODE
CHOP
YIELD
MESSXOI
COO!
PUNA
Uii wfrh Bolic Trtainwnrt
( Initial bwllrf-up) or high
P-K toll r*il l*v*li
PjOS
K20
PUN 1
Ult (or gradual lulld-up
whtn latic P-K ticaiHwnii
«. r-ol o^liMt
N
l-l"i
KiU
Figure 3-16 - Field Soil Test Information and Report and Interpretation Forms
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3-20
Many nutrients can be controlled, or prevented from leaving a farm,
through control of fine-grained sediments upon which they are adsorbed.
Soluble nutrients such as nitrates, however, are not trapped with the
sediment. They move with runoff or ground water (Reference No. 3-1).
It is fallacious to assume that all N applied will be utilized by a
crop. Being soluble, considerable portions of it will escape the root
zone of the plant. This especially depends upon the type, time and
weather conditions during application.
The method of applying nutrients is an important control measure
for there is a much greater pollution potential from surface applied
nutrients than from nutrients incorporated into the soil during appli-
cation (Figures 3-17 and 3-18). The methods of application, available
must play a role in developing management practices.
Figure 3-17 Poor Application of Anhydrous Ammonia, Shown By Escaping
Gas. Proper Application, At A Depth of From 6 to 8 Inches
Will Prevent Its Volatilization and Loss Into The Atmosphere
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3-21
Figure 3-18 - Farmer Following Manure Spreader With Plow To
Incorporate Manure Into The Soils
Alternating, or rotating crops which require little or no nitrogen
from fertilizer, such as legumes, with crops which have large fertilizer
requirements can substantially reduce the long-term average quantity
of nitrogen which can be leached from the soils. Use of alfalfa, or other
deep-rooted crops, such as winter wheat, to utilize the nitrates from
deep zones can reduce the possibility of nitrates being leached and
moving into ground or surface waters. Winter cover crops also can
function to extract soil moisture, which contains nitrates, during the
fall and spring seasons. This makes less quantities of the nitrates
available to cause pollution (Reference No. 3-4).
Fertilizers should be applied to the land when the potential for
intense precipitation and excess surface runoff is minimal. Slow release
fertilizers can be used on very sandy soils. Application of manures or
fertilizers to snow covered or frozen ground can be an extremely poor
practice. When a thaw occurs, potential pollution problems may be created
by nutrients and organic matter included in runoff.
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3-22
Control of Pesticides
As with nutrients, best management practices for the control of
pesticides must include a consideration of the timing, type, amount,
and method of application. These practices can be used in conjunction
with an integrated pest management (IPM) network which provides for
the best combination of all available methods to manage and control
all pests such as insects, weeds, diseases, nematodes, and rodents.
At least 30 States have programs covering a variety of crops. The
Cooperative Extension Service in corporation with EPA and the State
is responsible for the IPM network.
Integrated pest management combines traditional methods such as
crop rotation with measures using sophisticated insect traps and computer
analyses of the life cycle of insects that show best how to interrupt it.
The use of chemical poisons occurs only as a last resort. By keeping
a tally of the numbers and types of pests present and matching that against
computer analyses of their movement and mortality patterns, one can
determine the balance of pests and their predators and which of the pests
are likely to cause problems and when. In extreme cases the solution
may be application of pesticides but more often there is an organic or
other remedy.
As with nutrients, some pesticides adsorb to sediment particles and
will be prevented from leaving the area of application through the use
of effective sediment control measures. Additional control for these
pesticides, and the soluble portions which move with the surface runoff
and ground water must be achieved by requiring proper application pro-
cedures, reduction in the opportunity for accidental spillage, and proper
disposal of containers as well as waste materials (Reference Nos. 3-1 and 3-4).
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3-23
The use of pesticides for control of insects, fungi, weeds, rodents,
and similar pests is restricted by Federal law; and State and local
restrictions also may apply. Strict adherence to recommended practices
is necessary to limit the possibility of these materials creating nonpoint
source pollution problems. Application procedures should comply with
registered label directions and the equipment cleaned in a proper manner
after use, or disposed of properly (Reference Nos. 3-5 through 3-8,
and Page 2-6 of this Guidance).
Pesticide volatilization can occur after pesticides have been applied
or during application to possibly introduce pollutants into the environment
(See Figure 3-17). Evaporation of the water portion of droplets can reduce
their size and cause drift. Improper, inadequate, or careless disposal
of used pesticide containers, equipment, or excess materials can result
in pollution of surface or ground waters or can possibly kill nontarget
terrestrial or aquatic life.
Application of pesticides immediately prior to periods of intense
rainfall should be avoided as the runoff will transport the materials off
the area of application. Aerial or other types of spray application should
be restricted to periods of time and to areas where wind velocities are
inadequate to cause drift of the materials. Periods of temperature
inversion should also be avoided. Inversions result where air tempera-
tures increase with altitude. A well developed inversion acts as a lid
suppressing the vertical movement of air through it. Drift of the pesti-
cides is related to pesticide particle or droplet, sizes, wind speeds,
height of application, the existence of a temperature inversion, etc.
Often, oils or emulsifiers are added to pesticides sprayed to increase
-------
a-24
the size of droplets and so reduce the drift hazard. The relationship
between pesticide droplet and particle size and drift distance is indicated
in Table 3-1.
Particle Type
Aircraft spray:
Coarse
Medium
Fine
Air carrier sprays
Fine sprays and dusts
Usual dusts and aerosols
Aerosols
Drop Diameter
Microns
400
150
100
50
20
10
2
. ': Drift!/
Meters Feet
2.6 8.5
6.7 22
15 48
54 178
338 1,109
1,352 4,436
33,795 110,880
\J Distance a particle would be carried by a 4.8 kro/h (3 aph) wind while
falling 3 meters (10 feet).
Table 3-1 - Drift Pattern in Relation to Spray Particle Size
Pesticide volatilization can occur, after pesticides have been applied or
during application to possibly introduce pollutants into the environment
(See Figure 3-17). Evaporation of the water portion of droplets can
reduce their size and cause drift. Improper, inadequate, or careless
disposal of used pesticide containers, equipment, or excess materials
can result in pollution of surface or ground waters or can possibly
kill nontarget terrestrial or aquatic life.
Depth to ground water^ direction of its movement, and subsurface
hydrologic conditions must always be considered in underground disposal
-------
3-25
to prevent movement of waste materials into ground water. If pesticide -
containing materials are burned, pollution may result through washout
or fallout. Section 19 of the Federal Insecticide, Fungicide, and Rodenticide
Act as amended in 1972 (Public Law 92-516) directs the Administrator of
the Environmental Protection Agency to issue procedures and regulations
governing the disposal of pesticide containers. Implementing regulations
were published on May 23, 1978 (40 CRF, Part 165). Further dissemination
of these regulations,, and continuing education on the problems of incorrect
disposal and on the dangers of accidental poisoning, can lead to a reduction
in pollution from these sources.
Short lived or nonpersistent pesticides are environmentally preferable
[
and should be used where ever possible. Alternatives to pesticides
should always receive strong consideration. They can involve mechanical
measures (tillage practices to remove materials available to nourish
pests), biological controls (fungus coated seeds or predator insects),
insect sterilization (releasing large numbers of sterilized male insects
to fertilize females), insect toxins (use of naturally-occurring substances
to poison pests), insect attractants (such as concentrated insect sexual
attractant hormones), and development of disease-resistant crops.
Irrigated Crop Production
Erosion and sediment control practices for use in nonirrigated crop
production are also applicable to irrigated agricultural areas during
periods when irrigation water is not being applied and sediment losses
are due to rainfall and surface runoff and possibly wind erosion. Some
modification of these measures, particularly structural ones, may be
-------
3-26
required to comply with changes in topography or in differences in
operation activities. Nutrients and pesticide control practices also are
applicable to irrigated crop production.
The principal difference between irrigated and nonirrigated crop
production nonpoint source pollution control involve the excess salinities
and erosion and sediment runoff caused by the application of supplemental
water. The natural salt content of applied water increases due to evaporation
and transpiration processes (use by plants). Leaching of soluble salts from
soils and underlying geologic materials results in the introduction of
additional salts. Nonpoint source pollution control BMP's must consider
these processes to prevent or reduce nonpoint source pollution from salts.
During periods of low rainfall, when natural erosion and other processes
are almost inoperative, application of supplemental water for irrigation
purposes can cause erosion and runoff of sediments. Control of sediments
during this time must be designed in accordance with hydraulic conditions
caused by the flow of applied water.
Salinity Control
It is almost impossible to prevent some degradation of water quality
when irrigation of cropland continues for periods of time (Reference
No, 3-9). Even if salt loading (the addition of dissolved salts to water from
both natural and manmade sources) is prevented, the evapotranspiration
process, which extract nearly pure water from the soil solutions, would
cause salt concentrations. Control of irrigation return flow, however,
is essential and so measures must be developed to minimize both the
addition of salts and the concentrating effects of evapotranspiration.
-------
3-27
Research is being conducted which indicate that salinity control
may be accomplished partly by improving the presently-used irrigation
and drainage practices (Reference No. 3-10). The basic philosophy behind
the work is that the soil profile above the ground water body can be
used as a salt storage reservoir. By proper irrigation management,
the salt may be held indefinitely until released by leaching with excess
water. Some studies indicate that very small leaching fractions (as
small as 1-3%) can be used over long periods of time without the accumu-
lated salts affecting crop yields. Under certain conditions, these studies
suggest that salt may be precipitated out and stored within the soil layers
without significantly creating adverse effects on farming operations.
Research studies involve small areas under controlled conditions however.
Extreme caution must be used before concluding that the necessary
small leaching fractions can be feasibly achieved on a commercial scale.
Reducing Seepage Losses, Delivery Systems: Water conveyance
channels, beginning with major canals which convey water from diversion
facilities, or wells, to irrigation districts and farm systems and terminat-
ing in lateral distribution networks, in many areas are inefficient and
so have excess water loss from seepage. This water loss from main
delivery systems can be as high as 70% in some areas. After delivery
of the water to a farm, 30-40% of the water can be lost from on-farm
ditches and from inefficient crop production activities. The water lost
may either be consumed by non-agricultural vegetation, evaporate into
the atmosphere, or move into ground or surface water bodies. In all
cases, its salinity increases due to the concentrating effects of evapo-
transpiration and the leaching of minerals from soils and other materials.
-------
3-28
If these unnecessary losses of water can be prevented, or reduced,
water pollution by salinity can be reduced.
Reduction in water losses from conveyance facilities can be accomplished
by providing impervious linings to canals or by using pipelines for conveyance,
Relatively impervious canal linings may be formed of compacted clayey
soils, some type of asphalt or concrete, or plastic membranes. (Figures
3-19 and 3-20). Lining should be incorporated into all irrigation project
~ :-1
^
Figure 3-19 - Water Conveyance Ditch Being Lined with Air-blown Concrete.
distribution systems unless natural soils are so impervious that water losses
are insignificant. It is a proven, effective deterrent to irrigation water
quality deterioration (Reference No. 3-11).
-------
3-29
Figure 3-20 - Large Conveyance Channel Being Lined with Plastic.
A problem inherent in an open ditch, or canal, involves evaporation
from the free water surface. This can be resolved by using pipe convey-
ances composed of steel, concrete or plastics. Pipelines not only eliminate
evaporation and seepage losses, they provide better flow control regulation
and usually occupy less surface area (Reference No. 3-11). Figure 3-21
shows a pipeline under construction.
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3-30
Figure 2-21 - Installation of 30-inch Diameter Pipe for Irrigation
Distribution System.
Lining Terminal Storage Facilities: Irrigation storage reservoirs often
are used to "firm up" water supplies. They provide adequate quantities
of water during periods when irrigation demands exceed the rates of
water being supplied. For example, low productivity wells can supply
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3-31
water continuously to a reservoir while the latter is used intermittently
to irrigate at a rate greater than the wells can supply. These reservoirs
may be excavated, partially excavated and formed of embankment materials,
or constructed by placing an embankment across a watercourse. (See
Figure 3-22).
Figure 3-22 - Irrigation Storage Reservoir Being Lined With Air-blown
Concrete. Sealing The Walls and Floor of The Structure
Virtually Eliminates Seepage Losses.
Unless the storage facilities are situated in or on impervious ground,
they will be sources of seepage. This loss of water, and subsequent
leaching problems, can be prevented by lining the reservoir with a
blanket, or layer, of impervious materials. As in the delivery systems
these impervious materials can consist of compacted earth fill, concrete,
-------
3-32
asphalt, or plastic. Detailed suggested lining materials and methods of
application are provided by the U. S. Agricultural Research Service,
Soil Conservation Service and the Bureau of Reclamation. (Reference
Nos. 3-12 through 3-14).
Increasing the irrigator's awareness of the quantities of water being
lost from delivery systems and storage reservoirs may initiate his action
to increase the efficiencies of his systems. Correct measurements of
quantities of water being supplied to a system and the quantities leaving
the system are required for sound water management. They will indicate
where losses are occurring, their magnitude, and possibly what problems
result. At present, few systems contain provision for metering or
regulating the amounts of water at principal delivery points.
Proper Irrigation Water Management: Optimizing the quantity of
irrigation water applied and the frequency of application will do much
to reduce the salt concentrations and loadings in irrigation return flows.
Presently used irrigation methods and State water rights, particularly
in the semi-arid West, promote the widespread use of excess quantities
of water which, in some cases, are detrimental to optimum crop yields.
If only the quantity of water required to meet leaching needs and to
satisfy plant intakes were applied, less additional leaching and movement
of salts from soils would occur and more good quality water would
remain in receiving streams or ground water reservoirs to dilute salt
loads resulting from the water use by the plant species (Reference No. 3-15).
Controlled application of irrigation water through proper scheduling
will result in reduction of excess seepage losses and surface runoff while
still maintaining the correct moisture content in the soil root zone area.
-------
3-33
Proper irrigation scheduling involves a process for applying only the
optimum quantity of water to a particular crop when it is needed. In
many areas a field is irrigated when it is dry rather than attempting
to maintain an optimum level of moisture in the soil. Over application
of water on an intermittent basis is done frequently. It may cause
possible crop damage, excess surface runoff, or the deep percolation
of water. Some studies in the western States indicate that irrigation
efficiencies are less than 50%. Over application of water is occurring
due to poor irrigation management and because the water may not be
available in the future. As a result, water is not being applied when
plants require it. Essentially, the reservoirs of soil moisture are
not being fully utilized.
On-farm irrigation water management practices can be so
sophisticated as to require computers for scheduling the application
of water. Less sophisticated practices can be applied by the irrigator
to reduce water losses and the quantities of irrigation return flows.
They include determining the available soil moisture and related
organic demands as a guide for water application, preventing overflow
from ditches and laterals, improving the distribution of water over a
field by eliminating irregular elevation differences, providing contoured
terraces to prevent runoff; and selecting prudent irrigation methods
(Figure 3-23 and 3-24). Substantial reductions can be achieved in
the quantity of water applied by leveling, or releveling the land to
obtain a more favorable configuration. As much as 40 to 50% reduction
may result after leveling and the installation of a simple water measuring
device (Reference No. 3-11).
-------
3-34
Figure 3-23 - Field Moisture Check Sheet and Soil Auger for Obtaining Samples.
The U.S. Bureau of Reclamation,Cooperative Extension Service, and
Soil Conservation Service, as well as private consulting firms, have
available irrigation water management services and useful information
for increasing the efficiencies of irrigation practices.
Surface irrigation and sprinkler systems comprise the two principal
basic methods of applying water to croplands. Selection of the method to
be used depends upon the topographic conditions, soils characteristics,
quality of water available, plant tolerance and water requirements, climatic
conditions, and similar local variables. Surface irrigation involves the
direct application of water to the topographically higher area of a field
from which it moves by gravity flow, to lower areas. Distribution of
the water is dependent upon natural flow. It can involve flooding of an
entire field or just directing the flow of water down furrows between rows
-------
---
' * - • -" - -
« - -— ™-^" •"*
.-- .•-.-
%» ' Z- • -* *_
T - —>-;*;^
CO
I
oo
tn
Figure 3-24 - Surface Irrigation of An Orchard
-------
3-36
of crops (Figure 3-24). Excessive or rapid application of water should be
prevented as it may result in excessive water losses and the resultant
leaching of salts from the soils or cause severe erosion problems.
A fairly new modification of the surface application method is termed
trickle or drip irrigation (Figure 3-25). This type of irrigation, as the name
Figure 3-25 - Young Almond Orchard Being Irrigated by Drip Irrigation System
-------
3-37
implies, results in the application of minor flows of water closely
adjacent to the root zone of the crops. Application of water can be done
from surface pipe systems or from pipes buried at shallow depths in
the root zone. Compared with most other irrigation systems, drip and
trickle irrigation wastes much less water and so evaporation is reduced,
leaching minimized, and return flows of applied water decreased. Since
there can be problems resulting from this type of irrigation method
as well as benefits; proper management will involve a consideration
of all alternatives prior to its use. Information on some advantages and
disadvantages of drip and trickle irrigation are presented in Reference
No. 3-16).
v
The sprinkler method can be used on lands of irregular topography
and on many types of soils (Figure 3-26). Application of water is similar
to the way it is naturally applied in that a uniform distribution can be
made over the entire field. In contrast to nature's rainfall, however,
sprinkler irrigation can be controlled so that only an optimum amount
of water is applied at a selected rate. Excess runoff can be prevented
and so salt loading, leaching and possibly erosion are reduced. The
sprinkler method of irrigation is extremely flexible in operation and
can even be used to apply selected quantities of fertilizers or pesticides
to crops.
-------
00
CO
Figure 3-26 - Sprinkler System Supplied By Well Yielding 800 Gallons Per Minute
-------
3-39
Controlling Sediment and Other Pollutants
The principles for controlling sediments, pesticides, nutrients and
other pollutants resulting from non-irrigated crop production activities
also apply to irrigated agriculture. For erosion and sediment control
they involve vegetative coverings for soils subject to erosion, reducing
the velocities of flowing water so that erosion and sediment transport
is prevented, and trapping sediments that have been eroded and are being
transported from the agricultural area in detention ponds or pits.
Providing non-erodible impervious linings for open water distribution
channels and storage or detention facilities; locating grade-control, check
dam structures where possible erosion may occur; and limiting the quantity
and rate of surface water application to reduce runoff and prevent erosion
are Best Management Practices for reducing and preventing erosion and
sediment losses from irrigation. Lining provides structural stability
to irrigation channels; prevents failure of side slopes, and eliminates
erosion by high-velocity flows. Grade control and other erosion prevention
structures maintain the hydraulic gradient of the channel section and
prevent headward (up-slope) erosion and subsequent sediment losses
(Figure 3-27). Judicious management of applied water reduces unnecessary
runoff and possible erosion (Figure 3-28, 29, and 30).
-------
. ..; . .; ' - '• ••
CO
I
Figure 3-27 - Poorly-installed Water Control Structure
Allowed Erosion to Occur
-------
oo
i
Figure 3-28 -
Concrete-lined Irrigation Ditch Prevents Erosion
and Prevents Seepage Losses
-------
r-
,_.''_
1
:i;T
• . T
.-
- - , -
i~* • ». '
Figure 3-29 -
Concrete Stilling Basin At Discharge End of
Deep Well Pump Prevents Erosion of Sediments
Which Can Be Transported Into Lateral System
-------
-
.-.
Figure 3-30 -
Erosion In An Irrigated Field. Caused By Applying
Too Much Water To Rows That Are Too Long (2000 feet)
-------
3-44
As in non-irrigated crop production, effective sediment control
measures will prevent the runoff of many of the fertilizers and nutrients
which are adsorbed to soil particles. Using only optimum quantities of
either pesticides or fertilizers and applying them at the most effective
times are best management practices to minimize possible runoff of
pollutants. In irrigated areas, effective management of applied water
can be used to prevent movement of excess water containing nutrients, or
other materials, below the root zone of crops into ground water reservoirs.
Excess Ground Water Extractions
The extraction of excess quantities of water from ground water
aquifers, in excess of their long-term safe yields, can result in
depletion of supplies. Ground water levels will decline and possible
sea water intrusion, intrusion or interaquifer transfer of salt water
from marine deposits, or subsidence of the land surface may result.
Control measures should involve the development of proper well
construction procedures, effective distribution of wells, ground water
recharge facilities, and possible conjuntive use of both surface and
ground water supplies. Adequate well construction will prevent the
movement of poor quality waters from one aquifer into another through
the well bore itself. Wells distributed in patterns that prevent local
concentration of pumpage, reduce the possibility of localized water
table or pressure level depressions. Provision for ground water recharge,
possibly in areas of excessive withdrawals and the application of con-
junctive use methods will function to provide additional water supplies
directly to aquifers to offset the quantities withdrawn.
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3-45
Confined Animal Production
This guidance document involves control of pollution from confined
animal production facilities that are not covered under the National
Pollution Discharge Elimination System. Feeding operations covered
by the NPDES program involve point sources and should not be considered
in this guidance for nonpoint sources. The following Tables 3-2, 3-3, and
3-4 define those facilities that are controlled by the NPDES program.
For more information on program elements necessary for participation
in this system see the attached copy of the Federal Register, Dated
March 18, 1976. (Appendix B).
Confined animal facilities vary in design from open lots where there
is little cover or protection for the animals to those that are totally
confined in buildings. In confined facilities, animals are completely
housed to protect them from severe winter conditions and muddy ground.
Feedlots with partial confinement also exist. In these latter facilities,
animals are free to move about in the lot but also are provided with
protective shelters or buildings (See Figure 3-31). Variations in surface
configuration and characteristics of each facility can occur and lot
surfaces may be unpaved, partially paved, or completely covered with
an impervious material.
Best Management Practices for controlling, or preventing, the generation
and runoff of nonpoint source pollution from confined animal production
facilities include principally control of runoff water and the adequate storage,
treatment, and disposal of waste materials (Reference No. 3-18). Runoff
control involves preventing outside runoff from entering the feedlot.
-------
3-46
Operations with 1000
or more animal units
Operations with less than
1000 but with 300 or
more animal units
Operations with less than
300 animal units
:'ermi-t
required
for all
operations
Lth
discharges
of pollutants
Permit required if operation
1) Discharges pollutants
through a man-made convey-
ance, 0£
2) Discharges pollutants
into waters passing through
or coming into direct con-
tact with animals in the con-
fined area.
No permit required
(unless case-by-caae
designation as provided
below)
Operations subject to case-
by-case designation requiring
an individual permit only
after onsite inspection
and notice to the owner or
operator.
Case-by-case designation only it
operation
1) Discharges pollutants through
a man-made conveyance, or
2) Discharges pollutants into
waters passing through or
coming into direct contact with
the animals in the confined
area ;
AND
After on-site inspection,
written notice is transmitted
to the owner or operator.
Table 3-2 Concentrated Animal Feeding Operations
where it can contact waste materials. It also includes containing runoff
that has been generated within the facilities and is contaminated by
manure and other wastes. Waste storage, treatment, and disposal
techniques will depend upon the volume and moisture characteristics of the
wastes generated, amount of acreage involved, and the type of animal
production facility and wastes management system used.
-------
3-47
Types of animals
Slaughter and feeder cattle
Mature dairy cattle— milker and dry....
Ml swine over 55 pounds
Sht-p
Laying hens and broilers:
Facilities with continuous overflow
waterers
Facilities with liquid manure
handling systems
1,000 animal unit
equivalent
1,000
700
2,500
10,000
55 000
5 000
. .100 000
. . 30,000
300 animal unit
equivalent
300
200
750
3 000
16 500
1 500
30 000
9,000
Table 3-3 - Animal Unit Equivalents
Slaughter and feeder cattle
Nature dairy cattle
Swine over 55 pounds
Sheep
Example :
Number of animals
Slaughter and feeder cattle . ...
Swine over 55 pounds
Total
1.0
1.4
0.4
0.1
600 X 1.0=600
200 X 1.4-280
500 X 0.4=200
1080
Exemption. No animal feeding operation requires a NPDES permit if it
discharges only in the event of a 25 year, 24 hour storm event.
Table 3-4 - Animal Equivalent Multiples
[Operations with 1, 000 animal units are those which have the number
of animals listed in Table 3-3 under the 1, 000 animal unit equivalent
column. Operations with 300 animal units are those which have the
number of animals listed under the 300 animal unit equivalent column.
Table 3-4 lists the multiples to be used when figuring the number of
animal units at an operation if a combination of types of animals is involved.
-------
3-48
Studies have been conducted regarding recycling of feedlot wastes as
livestock feed (Reference No. 3-17). Partial or continuous recycling of
these wastes as feed materials could reduce the total amount of wastes
required to be disposed and also the biological oxygen demand associated
with its decomposition through the loss of organic matter. Animal wastes
may provide such useful nutrients as fiber, nitrogen, energy and minerals
in the diet of livestock.
Control of Outside Runoff
Runoff water from outside of confined animal production facilities must
be prevented from entering unless it is an integral part of the designed
disposal system Figure 3-31). It prevents uncontaminated runoff from
contacting manure and other wastes and transporting them from the site
area. It also reduces the volume of water which must be collected
and disposed of or treated.
Diversion To Divert
Unpolluted Water
HOLDING
POND
Mt-
E"
i
_,'• bimii
J
I ./.#
••••.-.-/.•;.•« .y.-v-v
••'•;/.'•;••;/.
•pron'
v'-vv'-'-
oll«y
*$£
>H /
I *V:;:-'
bunk
|| CROSS SECTION
Arrows show the direction of drainage.
Figure 3-31 - Sketch and Cross-section of Confined Animal Production Facility
Showing Diversions Which Prevent Runoff From Entering The Si'
and Directing Contaminated Runoff Into a Holding Pond. Note
Cross-section Showing Topography of Facility.
-------
3-49
Proper location of the facilities with regard to topography, soils
and geologic conditions, ground water and surface water proximity will
help minimize the possibility of outside surface water entering the
facility. Perimeter diversion ditches and/or berms are the principal
structures to divert surface runoff from upslope areas and by-pass it
into adjacent well protected areas. Ground water or springs that could
discharge into the feedlot may be cut off above their source areas by
drain wells, "french drains", or other measures and diverted to a pro-
tected area. Capacity for the selected design storm, with an added
factor for safety, must be provided for these structures to ensure control
of the runoff. Design storms must be selected in accordance with local
precipitation, soils, vegetative, and other conditions.
If a stream extends into the confined animal facility, relocation should
be considered, or the stream diverted away from, or around, the area.
This may involve the use of diversion structures, lined channel sections,
or perhaps pipelines.
Onsite Runoff Control
Runoff water that has come into contact with manures and other wastes
must be prevented from leaving the animal production facility to degrade
quality of water further downstream. The slope of the animal production
facility must be adequate to remove runoff quickly and drainage channels,
or other structural measures such as diversions, must be provided to
ensure transmittal of fluids to collection or retention structures. Since
some solid materials are usually carried in the runoff, some consideration
within the design of the system must provide for their removal. Porous
dams or some other structural measures in drainage channels can be
-------
3-50
•i
used to decrease the velocity of runoff flow and allow settlement of
solids. Removal of the settled solids can be done during dry periods
with mechanized equipment. If needed, draglines, can be used during
wet conditions to remove the solids. Disposal of these materials should
be where they are not apt to be transported into water bodies by runoff
(See Page 3-51).
Settling basins at the end of conveyance channels can efficiently
remove much of the solids contained in the runoff. Since they may be
relatively deep in order to provide sufficient storage space, removal
of solids from them may be difficult without special types of equipment.
Many different types of ponds with varied outlet elevations can be
designed for the most efficient solids removal. During design, con-
sideration should be made with regard to how the solids are to be
removed from each structure in order to ensure that retention capacities
are maintained (Figure 3-32). Outlet pipes or some other types of structures
or pumps, must be used to dewater the basins for removal of the solids.
CRUSHED
./,
•^-?— — 0-^""L_d '
___ 100 '
SIOCK ?
~~~-' ~ "~~r~7T~' n— -*S''
" PLANKING
n „ WOOD POST
1 . n fn fc^ ,vi
'" " l"^"' ^^"~~^^ ~^—r^ i
100'
" 1
100' i
LIQUID
HOLDING
POND
Figure 3-32 - Sketch of A Series of Porous Dams Forming Settling Basins
For Removing Solids From Runoff Prior to Entering
Holding Pond. Crushed Rock Will Require Periodic
Cleaning or Replacement to Retain Filtering Capacity
-------
3-51
Settling basins can be constructed in the form of terraces or
multiple terraces. They provide large areas for storage over
periods of time to allow for efficient solids removal.
Collection or holding ponds, are used to provide storage of fluids until
disposal can be accomplished (See Figure 3-32 and 3-33). They should
be designed to store the volume needed for disposal management with
an additional storage capacity to accommodate runoff from the estimated
design storm. Some sources estimate that the management volume should
be at least 50% of the volume expected from the design storm (Reference
No. 3-18).
Any fluid detention facility must be designed with subsurface conditions
in mind so that infiltration of pollutants does not create a ground water problem.
Particularly in areas of shallow water table conditions, ground water
pollution is always a potential unless the bottoms of ponds containing
pollutants are sealed with impervious "blankets" of clay or other materials.
Disposal of Wastes In Runoff Water
Disposing of wastes carried by runoff from animal production facilities
on the land probably is the most economical and practical means of getting
rid of potential pollutant materials. It involves waste disposal by evaporation
and/or irrigation practices.
Disposal By Evaporation: Evaporation of liquid wastes may be the most
economical method in areas of the U. S. where the annual evaporation
exceeds precipitation by 762 millimeters (30 inches) (Reference No. 3-18).
Lagoons for evaporation purposes must provide a surface area sufficient
to result in evaporation of one year's waste fluid plus the quantity of rain
that falls within the structure. Open areas with fairly continuous winds
-------
3-52
blowing across them will be favorable for high/evaporation rates.
An additional "safety factor" should be provided to make up for additional
capacity required during exceedingly wet years. Figure 3-33 presents
a map of the U. S. showing contours of the moisture deficit (annual evaporation
minus rainfall). The 762 millimeter contour line extends through the
extremely southwestern portion of the U. S.
Design of the evaporation disposal facility should consider the monthly
rainfall, evaporation, and runoff quantities to be involved in the area in
order to determine the size of the facility needed for evaporation disposal.
Rainfall and evaporation data can be obtained from the U. S. National
Weather Service, Department of Commerce. The amount of rainfall that
actually becomes runoff from an area can be estimated in several ways.
Probably the most applicable provides information on estimating runoff
through the use of "Watershed Curve Numbers". It is presented in the
Soil Conservation Service "National Engineering Handbook, Section 4,
Hydrology" and "Engineering Field Manual" (Reference No. 3-2). The
curve numbers are "soil-cover" complex numbers which indicate their
relative value as direct runoff produces. The higher the number, the
greater the runoff to be expected from a storm.
Large areas of land are usually required for evaporation processes
and the design of ponds should provide for the largest surface area possible.
Reshaping of the land or grade separation structures may be required to
do this.
Disposal by Irrigation: Disposing of feedlot wastes by irrigation
is probably the most practical disposal method. It can be used to
provide nutrients needed for crop production or just used to get rid
-------
50
10
50 \ 30 (762 Millimeters)
10" (Excess
Moisture)
co
en
u>
40"
Figure 3-33 - LINES OF MOISTURE DEFICIT FOR THE UNITED STATES
-------
3-54
of waste materials. Excess application of wastes may cause crop yields
to diminish and/or runoff of pollutants to occur.
The design of the irrigation system will depend on the purpose for
irrigating, as well as, the topographic conditions, the type of vegetation
or crop being irrigated, and the equipment.
Disposal of Liquid, Slurry, or Solid Wastes on Land
Placing animal wastes on agricultural lands probably is one of the
oldest of man's fertilization programs. Now mechanized or hydraulic
equipment is used to remove the large quantities of manures from
confined animal production facilities and either place it directly on or
in the soil or place it in an adequate storage facility prior to application.
If stored, the storage facilities must be designed to prevent pollution
from occurring as a result. Application of animal wastes on the land,
similar to other disposal methods, must be done on the basis of type
of crop expected to be produced, the topographic and soils conditions,
the characteristics of the wastes, and the climatic conditions in the
disposal area. A consideration of the possibility of movement of fluids
into underlying ground water supplies must always receive emphasis.
Excess quantities applied may reduce crop yields due to increased
in salt contents in the soils. They can also alter the physical properties
of the soils and influence the microflora within these soils.
The following site conditions should be met when disposing manures
on land:
1. Surface runoff must be controlled.
2. Soils and vegetation present act as a "sink" to retain all
of the nutrients in the manures. (Reference No. 3-19).
-------
3-55
Wastes should be spread as uniformly as possible and incorporated
into the soils. Incorporation into soil layers greatly reduces the chance
of them being transported from the site by runoff waters. Scheduling
of manure application should be done so that the chances of the materials
remaining in place are optimal. This involves times when vegetation
or crop residues are at their maximum and runoff at a minimum. Any
practices or activities that can minimize or prevent the contact between
runoff water and applied manures, which promote the infiltration of
rainfall, or reduce the quantity of runoff also act to prevent or reduce
the' pollution potential of animal wastes applied to the land. They can
involve application just prior to plowing, or on plowed fields; before
the snow season begins so the snow cover provides some protection
from runoff; or early enough for growing crops to utilize many of the
nutrients available (Figures 3-34 and 3-35).
Application rates depend on the ability of the soils and crops, or other
vegetation, to utilize or otherwise fix the nutrients in place. Since the
animal manures must remain where applied for these processes to take
place, the soil characteristics such'as permeability, depth, and chemical
quality must be considered. Additional factors of importance are the
slope of the land, type of vegetative cover, and the climate and length
of growing season (Reference No. 3-19).
Pastured and Grazing Animal Production
Pastured and grazing animals are essentially living under unconfined
conditions. If properly done, this is probably the most environmentally
sound method of containing animals for man's use with regard to pollution
prevention. Concentrations of the animals, and the most severe nonpoint
-------
3-56
. \.TO.«'': i . ¥5ssk*«!t'>fv-'*S*yiBa,w*tii
^.WlStfeJ
Figure 3-34 - Liquid, or Slurry, Wastes From Confined Animal Production
Facilities Being Applied to Alfalfa After First Cutting
-------
jy. ~ ...
- '
•"- -' ~x^ •
-' - - •" V.-r_ V?
» ''» "• v" - - •"-,:"' • » -
-*"." - -''*''
» ' ^ * - - . -
: - ~- '*•>'
OJ
i
en
Figure 3-35 - Applying Solid Animal Wastes (Manures) To Freshly-
Plowed Ground
-------
3-58
source pollution problems, occur in the vicinity of watering, feeding,
milking, and probably "loafing" areas. Overgrazing, or the use of
the land by too many animals for too long a period of time, creates a
most severe problem, particularly with regard to erosion and sediment
losses.
Control through Best Management Practices, as with other agricultural
activities, involves first developing and then implementing one or more
of many animal management systems to minimize or prevent the generation
of a pollution problem. This will involve an evaluation of the forage
capacity of the land, grazing habits and schedules of the animals, physical
and chemical characteristics of the soils, the slope and other topographical
conditions of the area, and the climatic conditions. Uniform distribution
of livestock grazing will help prevent localized problems while other
areas are in good condition. Use of proper grazing practices will prevent
detrimental plant composition changes that could ultimately result in
conditions favorable for extensive erosion and sediment losses.
Animals graze their pastures and rangelands selectively by both plant
species and areas (Reference No. 3-20). The more palatable plants and
easily accessible areas will be used more consistently than other sources.
Continuous grazing by the same type of animal, and in the same season
at normal stocking rate, tends to result in the most palatable and accessible
vegetation being depleted. The remaining plants will successively be
eradicated to ruin the pasture and deplete its protective vegetative cover.
Proper management can prevent this by periodically resting the pasture
or rangeland or possibly alternating, different types of grazing animals
on the land. The purpose of resting western rangelands is to:
-------
3-59
1. Permit plants the opportunity to renew their vigor.
2. Allow seeds.to ripen and seedlings to be established.
3. Allow plant residue to accumulate on the ground surface.
The amount of rest required for a range or pasture is determined
by the condition of the plant species that have been severely overused
during the critical green period. In semiarid western grazing, a period
of 1 to 2 years is adequate; however, other grazing - resting treatments-
can be used. A five-cycle treatment formula developed for the western
area is illustrated in Figure 3-36 below.
One
Cycle
YEAR
I st.
2 nd.
3rd.
4+h.
5th.
TREATMENT
A
8
C
D
E
MAIN TREATMENT EFFECT
Livestock production
Vigor, litter
Seed, seed trampling, vigor,
livestock production
Seedlings, vigor, litter
Seedlings, livestock production
Season
LEGEND
Y//A Grazing
Seed-ripe time (j)
Resting
Flowering "Hme or equivalent
Figure 3-36 - A 5-Treatment Grazing Formula (From Reference No. 3-20).
-------
3-60
The end results to be achieved by such a cycle of treatments include
increased plant vigor, more plants produced, and increased litter on the
ground to protect the soil. Grazing after the seed ripe time of Cycle 3
is important for getting seedlings established as the seeds are trampled
into the soil. If trampled into the soil at only a shallow depth, they have
an increased chance for germination and the establishment of seedlings.
Seeds should be trampled as soon as possible after falling to minimize
losses to birds, animals, and insects. These treatments keep the pasture
or range in adequate condition for grazing.
There are many alternative systems of sound grazing practices which
can be used to minimize or prevent pollution. It will necessarily be based
on a knowledge of the local conditions. By ensuring a vigorous and
extensive vegetative ground cover and protected and productive soil,
the potential for pollution by nonpoint source pollutants will be minimized
and the production of livestock maximized.
Each year, approximately 30% of the root system of rangeland grasses
must be replaced (Reference 3-21). This is necessary for healthy reproduc-
tion. A test has indicated that the amount of leaf volume removed directly
affect the growth of new roots. All root growth stopped when 80% of the
leaves were cut. When 90% of the leaves were removed, all root growth
ceased and did not resume until leaves grew back. Repeated removal
of leaves resulted in more severe root growth stoppage. This indicates
again that pasture and grazing lands must be rested from grazing activities.
A knowledge of the grazing habits of animals is important in developing
grazing management plans. Cattle usually graze from sunrise to ,mid -morning
and from late afternoon to sunset. Grazing also may occur during short
periods at night. For example, cattle graze for 6 to 10 hours and travel
-------
3-61
from 3 to 8 kilometers (about 2 to 5 miles) during the day. During the
remainder of the time travel is done for the purpose of using sources
\,N
of water, salts, and other minerals and to loaf in shaded areas while
ruminating.
Since cattle, and other animals, use some portions of pastures more
heavily than others, due to grazing preferences, vegetation will be depleted
principally in these areas unless suitable management is practiced. If
the depletion is-too severe, erosion and sediment losses may become
extensive. The grazing distribution problem may be resolved and
sediment pollution prevented by locating water, salt and mineral, and
other sources in accordance with range conditions. Since cattle travel
to their water supplies and salt and mineral sources periodically each
day, they tend to overgraze their routes to them. Providing additional
water sources and locating salt and mineral facilities in undergrazed
areas away from water supplies will give cattle the incentive to graze
more uniformly over an area. (See Figures 3-37 and 3-38).
Figure 3-37 - Temporary Salt Lick Can Be Easily Relocated. (Reference No. 3-2?
-------
3-62
Figure 3-38 - Small Water Pond Helps Relieve Grazing Pressure In Other
Areas Where Use May Be Excessive. (Reference No. 22)
A simple technique for determining where and how much grazing
is going on is to fence in a small square of vegetation and leave it for
the rest of the season (Figure 3-39). It will quickly be apparent how much
of the vegetation has been removed.
Figure 3-39 - Fenced Plot Indicating The Amount of Grazing Which Has
Occurred Outside Its Boundaries. (Reference No. 21).
-------
3-63
Streams and other water bodies in pastures or grazing land can
be to a great extent protected from pollution by nonpoint sources
activities if heavily grassed buffer strips are maintained adjacent to
them. These strips serve to decrease the velocity of sheet flow and
to filter out sediment and other pollutants being transported in runoff.
If fencing or some other techniques are used to keep animals out of
these buffers to prevent overgrazing, they will maintain their effective-
ness and the pollution potential will be minimized. In critical areas,
measures to prevent the physical contact between the animals and the
water may be necessary.
-------
3-64
CITED REFERENCES
3-1. U.S. Environmental Protection Agency "Methods and Practices
for Controlling Water Pollution from Agricultural Nonpoint Sources"
EPA-430/9-73-015, October, 1973.
3-2. U.S. Department of Agriculture, Soil Conservation Service
"Engineering Field Manual For Conservation Practices", 1969.
3-3. U.S. Department of Agriculture, Agricultural Research Service,
in cooperation with Kansas Agricultural Experiment Station "Wind
Erosion Forces in The United States and Their Use in Predicting
Soil Loss", Agricultural Handbook No. 346, April, 1968.
3-4. U.S. Environmental Protection Agency and Department of Agriculture
"Control of Water Pollution from Cropland, Volume I-A manual for
guideline development", November, 1975.
3-5. — - - --, "Control of Water Pollution from Cropland, Volume II-
An overview", June, 1976.
3-6. U.S. Environmental Protection Agency, "Regulations for the Acceptance
of Certain Pesticides and Recommended Procedures for the Disposal
and Storage of Pesticides and Pesticide Containers" Federal Register
Vol. 39, No. 85, Part IV. May 1, 1974.
3_7^ — — "Certification of Pesticide Applicators" Federal Register,
Vol. 39, No. 197, Part III, October 9, 1974.
3-8, _ _ _ _ pesticide Programs "Registration, Reregistration, and
Classification Procedures "Federal Register, Vol. 40, No. 129,
Part II, July 3, 1975.
3-9. U.S. Environmental Protection Agency "irrigation Management For
Control of Quality of Irrigation Return Flow", EPA-R2-73-265,
June, 1973.
-------
3-65
3-10. "Irrigation Management Affecting Quality and Quantity
of Return Flow", EPA-600/2-76-226, September, 1976.
3-11. "Evaluation of Salinity Created By Irrigation Return
Flows", EPA-430/9-74-006, January, 1974.
3-12. U.S. Department of Agriculture "Agricultural Research Service
Lining Irrigation Laterals and Farm Ditches", Information Bulletin
No. 242, November, 1961.
3-13. Soil Conservation Service, "Sealing Leaking Ponds and Reservoirs",
SCS-TP-150, February, 1968.
3-14. U.S. Department of The Interior Bureau of Reclamation, "Water
Systems Management Workshop Lecture Notes, 1971", November 1971.
3-15. Blackman, W. C., Jr; Willis, C. G. ; and Celnicker, A. C.,
"P. L. 92-500 V. Pollution By Irrigation Return Flow", American
Society of Civil Engineers Journal of The Irrigation and Drainage
Diversion, June, 1977.
3-16. Cole, Thomas E., "Subsurface and Trickle Irrigation. A Survey
of Potentials and Problems", Nuclear Desalinization Information
Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee,
November, 1971.
3-17. U.S. Environmental Protection Agency, Office of Research and
Development, "Influence of Recycling Beef Cattle Wastes On In-
digestible Residue Accumulation, " EPA-600/2-77-175. August, 1977.
3_18. , "Environment Protecting Concepts of Beef Cattle Feedlot
Wastes Management", Report on Project No. 21 AOY-05, July, 1973.
3-19. , "Design Parameters For The Land Application of Dairy
Manure", EPA-600/2-76-187, October, 1976.
3-20. U. S. Departments of Agriculture and Interior, "Principles of Rest -
Rotation Grazing and Multiple-Use Land Management, " Sept., 1970.
-------
3-66
3-21. U.S. Department of Agriculture, Soil Conservation Service.
"Grass: The Stockman's Crop, How to Harvest More of It",
Special Report, February, 1975.
3-22. , Forest Service, "Managing Public Rangelands",
AIB-315. October, 1967.
ADDITIONAL REFERENCES USED
1. U.S. Environmental Protection Agency, "Conservation Districts
and 208 Water Quality Management", Prepared by the National
Association of Conservation Districts under EPA Grant No.
T90057401-0, June, 1977.
2. U.S. Environmental Protection Agency, "Control of Sediments,
Nutrients, and Adsorbed Biocides In Surface Irrigation Return
Flows", Report on Interagency Project No. EPA-IAG-D5-F648,
April, 1976.
3. — - —, "Evaluation of Irrigation Scheduling For Salinitry Control
In Grand Valley", EPA-660/2-74-052, June, 1974.
4. — - - -, "Nitrogen and Irrigation Management To Reduce Return-
Flow Pollution In The Columbia Basin", EPA-600/2-76-158,
September, 1976.
5. - , "Prediction Modeling For Salinity Control In Irrigation
Return Flows", EPA-R2-73-168, March, 1973.
6. — - - -, "Evaluation of Drainage for Salinity Control In Grand
Valley", EPA-660/2-74-084, August, 1974.
7. -, "Management Practices Affecting Quality and Quantity
of Irrigation Return Flow", EPA-660/2-75-005, April, 1975.
8. The ComptroUer General of The United States, "Better Federal
Coordination Needed To Promote More Efficient Farm Irrigation",
Report To Congress, June 22, 1976.
-------
3-67
9. American Society of Civil Engineers, "Sediment Routing In
Irrigation Canal Systems", Preprint from Meeting of January 29 -
February 2, 1973.
10. U. S. Environmental Protection Agency, "Treatment and Ultimate
Disposal of Cattle Feedlot Wastes", EPA-660/2-75-013, June, 1975.
11. , "Design Criteria For Swine Waste Treatment Systems",
EPA-600/2-76-233, October, 1976.
12. — - -, "Demonstration of a Waste Disposal System for Livestock
Wastes", EPA-R2-73-245, May, 1973.
13. — - -, "Soil Modification for Denitrification and Phosphate
Reduction of Feedlot Waste", EPA-660/2-74-057, June, 1974.
14. — - -, "Liquid Aerobic Composting of Cattle Wastes and
Evaluation of By-Products", EPA-660/2-74-034, May, 1974.
15. , "Feasibility of Overland Flow Treatment of Feedlot
Runoff.
16. — - -, "Design Parameters For Animal Waste Treatment Systems-
Nitrogen Control", EPA-600/2-76-190, September, 1976.
17. -, "Design Parameters For Animal Waste Treatment Systems",
EPA-660/2-74-063, July, 1974.
18. U. S. Department of Agriculture, Soil Conservation Service, "A
Better Brand of Range Management", Soil Conservation. Volume 42,
No. 10, May, 1977.
19, > "What Is a Ranch Conservation Plan?", PA-637,
December, 1964.
20. U. S. Environmental Protection Agency, "A Study of the Efficiency
of the Use of Pesticides In Agriculture, " EPA-540/9-75-025, July
1975.
-------
4-1
CHAPTER 4
METHODOLOGY FOR ASSESSMENT OF POTENTIAL
AGRICULTURAL NONPOINT SOURCE POLLUTION PROBLEMS
The worldwide demand for agricultural products has caused an
intensification of crop and animal production in the U. S. The trend is
to employ modern technology to increase production on existing farm lands
and to place additional, and often marginal, lands into production. This
generally increases the quantities of fertilizers, pesticides, irrigation
waters, and other materials used. As a result, the potential for pollution
increases.
To some extent, nonpoint source pollution will result when any lands
are subjected to man's agricultural activities. If soil surfaces are dis-
turbed; surface runoff increased or concentrated; vegetation removed;
pesticides, nutrients, or other materials applied to the ground in greater
quantities than can be consumed by crops or organisms; or salts are con-
centrated and removed from irrigated lands by applied water, pollution can
result. Only the magnitude and extent of this pollution needs to be estimated.
This chapter provides information which can be used to predict and
approximate the magnitude of nonpoint source pollution which could result
from new lands being subjected to agricultural production activities or
existing farm lands where production is intensified or changed. The
methods discussed provide approximations only and should be used with
care by personnel that are competent in their use. Further and more
detailed information on methods will be presented in the Handbooks discussed
in Appendix A.
The assessment studies may indicate that certain areas are so sensitive
to changes caused by man's activities that they should be left in their natural
-------
4-2
grassland or woodland state and not placed into production. This may
be due to the possible magnitude of the potential pollution problems to
be created or to the costs required to prevent, or mitigate, environmental
damages. Highly-erodible soils on steep slopes, proximity to high-quality
surface or ground waters, occurrence of excess-natural salts or other
materials, and similar factors may initiate problems that are extremely
difficult to prevent or correct.
To assess the potential for proposed agricultural activities to generate
nonpoint source pollutants in an area and release them into waterways,
all available pertinent information must be obtained regarding the type
of activities to be conducted and the local climatic, soils, topographic,
and other conditions. The information on activities needed should include
the types of products to be produced (crops or animals) and their arrange-
ment, density, or pattern; kinds of tillage practices or other soil-disturbing
activities to be conducted; what pesticides, fertilizers, crop residueus, or
other additives are to be applied or disposed of; if irrigation water is to be
applied and what type of system is to be used, kinds of nonpoint source
pollution control measures proposed, and other data. Data on area conditions
necessary for assessment of the nonpoint source pollution potential should
include the quantity, frequency, and intensity of precipitation expected;
prevailing wind directions and velocities; composition, permeability, thick-
ness, and other physical characteristics of soils; proximity of the area
to surface water bodies, depth to ground water, and the quality of each
water source that could be affected by the activities; possible occurrence
of saline materials in or below soil horizons; and other factors.
Chapter 2 provides sources for obtaining some of this information
and emphasizes that the generation and runoff of pollution from agricultural
-------
4-3
areas are strongly dependent on climatic and other conditions that often
are highly variable. Many times, information needed to assess potential
pollution from nonpoint sources in areas that have never been subjected
to agricultural activities is lacking, particularly from readily available
agricultural sources. In this case, information sources may exist
as research reports or project reports done for other than agricultural
purposes. If not, it will have to be obtained by sampling or testing
or even estimated. Many times data can be obtained from a similar
area and interpolated for use.
Pollutants To Be Considered
Possible nonpoint source pollutants to consider for an area to be
subjected to agricultural activities for the first time or where activities
are being changed or intensified are discussed in some detail in Chapter 1
"Existing Problem Identification and Assessment". As a result, only a
summary will be provided here.
Nonpoint source pollutants generated by agricultural activities include
sediments nutrients, pesticides, salts, organic materials, and pathogens.
Many of the activities generate the same type of pollutants; however, the
magnitude and extent of the pollution resulting differs. They are uniquely
characteristic of the type of activity involved and so may require different
assessment techniques for determining the potential for pollution. Sediments
are generally considered the major pollutants from agriculture. They are
generated by any activity that disturbs the ground surface and leaves it
exposed to rainfall, wind, and runoff. Pollution from pesticides and
nutrients generally result from applied materials placed on croplands;
however, nutrients can be major problems as a result of wastes from
-------
4-4
feedlots and the animal production facilities. Salts generally become
nonpoint source pollutants as a result of irrigation of croplands. Salts
fed to animals in confined feeding facilities, however, can also become
potential pollutants. Organics and pathogens result from animal production
facilities. Probably confined facilities are the greatest potential sources
but pasture and rangelands can be water quality problems if the animals
can come into contact with water sources.
Probably, the only useful prediction methods that are available to
assess potential nonpoint source pollution problems involve sediment
losses. Methods to assess the potential for pollution from other materials
consist of comparing activities conducted in other similar areas and in
past times and the pollution resulting from these activities with pollution
to be expected from new areas of production. They will include evaluation
and comparison of management activities; application of pesticides,
nutrients and other materials; soils, geologic, topographic, ground
and surface water, and climatic conditions; and control measures applied.
If nonpoint pollution has occurred in the past from certain agricultural
activities, it is reasonable to assume that it will occur in new areas if
the same conditions exist and the activities are similar. Only the
application of Best Management Practices will reduce or prevent the
generation and runoff of the pollutants.
Assessing Potential Sediment Problems
Any agricultural activities which remove the vegetative cover from
the ground surface or disturb the soils and leave them exposed to the
energy of rainfall, wind, or runoff water create the potential for non-
point source pollution. Erosion will occur and transporting agents will
-------
4-5
carry sediment, perhaps with other pollutants, downstream toward
water bodies. If no pollution control measures are provided to prevent
or control this type of pollution, it will not be necessary to determine
if soil losses will occur, but only to determine their magnitude and
extent.
If new lands to be placed into production or agricultural practices
are to be changed on lands previously under production, the potential for
nonpoint source pollution exists. One way of estimating this potential
is to compare soils, topographic, cover, and climatic factors in the
new area with adjacent areas which are under production. If conditions
are similar, the same potential for sediment losses will exist for the
new lands as for the ones under production. Losses from sheet and
rill erosion processes on the new lands can be estimated by using the
Universal Soil Loss Equation A=RKLSCP. This equation, and the factors
in it, are briefly discussed in Chapter 2, Pages 2-18 and 2-19.
Runoff Determinations
Since erosion by water and the resulting soil losses from an
agricultural area is minor until runoff actually occurs, an estimation
of the amount of runoff to be expected in an area to be placed into
production should be conducted. This involves an evaluation of the
combined effect of soils, vegetative cover, topography, and other factors
on the amount of precipitation that actually becomes runoff in an area.
Probably the most applicable method for estimating runoff in this manner
is presented in the SCS "National Engineering Handbook, Section 4,
Hydrology" (Reference No. 4-1).
-------
4-6
A graph for the rapid determination of the quantity of runoff from
an area is presented in Figure 4-1. It is based upon a rainfall-runoff
relation formula and "soil-cover" complex curve numbers (CN's).
The curve numbers indicate the potential for runoff to occur when the
ground is not frozen. They are dependent upon the physical characteristics
of the soils in the basin and land use and treatment effects. Land use
includes the types of vegetative cover- litter or mulch, water surfaces,
or impervious surfaces existing in the area. Land treatment involves
any practice which may have been conducted or applied to revise the
flow of water.
The curve numbers indicate their relative value as direct runoff
producers. The higher the number, the greater amount of direct runoff
to be expected from a storm. Table 4-1 illustrates the types of curve
numbers obtained. Most areas, prior to being placed into agricultural
production, probably will approximate meadow and woods CN's.
Soil groups are characterized according to ability to absorb and transmit
water, with Group A being permeable and having a high infiltration rate.
Group D is the most impermeable and so has the highest runoff potential.
Sediment Losses
Sediment losses from an area can result from sheet and rill, gully,
or streambank erosion processes. Information for assessing these losses
can be found in Reference Nos. 4-2 through 4-7. A brief discussion on sheet
and rill erosion losses, along with an explanation of the Universal Soil
Loss Equation is presented on Pages 2-15 and 2-16 of Chapter 2. In some
areas, detailed or up-to-date soils and other information may be lacking
because no agricultural activities have been in operation. Numerical
-------
HYDROLOGY: SOLUTION OF RUNOFF EQUATION
P» 0 to 12 inches
0=0 to 8 inches
4567
RAINFALL (P) IN INCHES
10
FIGURE 4-1 - Estimating Direct Runoff Amounts From Storm Rainfall (From Reference No.-4-1)
-------
4-8 '
Land use
Fallow
Row crops
Small
grain
Cover
Treatment
or practice
Straight row
ii
it
Contoured
it
"and terraced
it it ii
Straight row
Contoured
"and terraced
Close -seeded Straight row
legumes I/
or
rotation
meadow
Pasture
or range
Meadow
Woods
Farmsteads
Roads (dirt)
(hard
ti ii
Contoured
it
"and terraced
"and terraced
Contoured
ti
ii
2/
surface) 2/
Hydrologic
condition
Poor
Good
Poor
Good
Poor
Good
Poor
Good
Poor
Good
Poor
Good
Poor
Good
Poor
Good
Poor
Good
Poor
Fair
Good
Poor
Fair
Good
Good
Poor
Fair
Good
Hydrologic soil group
A
77
72
67
70
65
66
62
65
63
63
61
61
59
66
58
64
55
63
51
68
49
39
47
25
6
30
45
36
25
59
72
74
B
86
81
78
79
75
74
71
76
75
74
73
72
70
77
72
75
69
73
67
79
69
61
67
59
35
58
66
60
55
74
82
84
C
91
88
85
84
82
80
78
84
83
82
81
79
78
85
81
83
78
80
76
86
79
7^
81
75
70
71
77
73
70
82
87
90
D
<*
91
89
88
86
82
81
88
87
85
84
82
81
89
85
85
83
83
80
89
84
80
88
83
79
78
83
79
77
86
89
92
I/ Close-drilled or broadcast.
2/ Including right-of-way.
TABLE 4-1 - Example of Curve Numbers For Soil and Treatment
Conditions (Reference No. 4-1).
-------
4-9
values for factors in the equation may not be available for these lands
and must be obtained by sampling and testing or estimated. They could
include the soil credibility factor (K). the length and slope factors
(L and S), and possibly the ground cover factor (C). The rainfall and
runoff erosivity index (R) will probably be similar to that in adjacent
lands that are under production. The supporting practice factor (P)
will be 1 as no support factor will have been applied to the lands where
no production has been carried out or that has not been in production
for a period of time.
Through the use of the USLE, with the estimated numerical values
for each factor, an approximate evaluation of potential soil losses can
be obtained. If more precise data on the values of the factors become
available from prior studies or other sources, the soil loss estimates
will become more accurate.
Gully erosion is a more advanced type of erosion than the sheet
and rill process and results from conditions which concentrate the flow
of runoff. The characteristics of soils, geologic, topographic, and
volume of runoff control the rate of a gully development and advance.
Probably the only way to predict potential sediment problems from
gully erosion is to compare the area that is planned to be placed into
production, or where agricultural practices are to be changed, with
a similar area where production is presently taking place. If the area
in production is affected by gullying and has similar soils, slopes, ground
cover, and other conditions, gully erosion can also be expected in the
planned new area when production takes place.
Measurement of the volume of sedimentary materials removed from
the gullys with a time period will indicate the quantity of sediments
-------
4-10
to be lost from the area. If different soils, geologic, topographic, or
other conditions are known to exist in the new area, an estimate may
be made as to how they could affect the soil losses from gully erosion.
Erosion from wind forces may be predicted through the use of data,
maps, and guidance presented in "Wind Erosion Forces In The United
States and Their Use In Predicting Soil Loss". The information pre-
sented includes the capacity of the wind to cause erosion of unprotected
soils, the preponderance of wind erosion forces in the prevailing direction
of the winds, and the prevailing wind direction throughout the United States.
Generally, wind erosion forces are highest in the spring of the year
and lowest during the summer. Some areas, however, might have their
highest erosion forces during the summer. Table 4-2 provides information
on wind forces and direction in several areas of Arizona and California.
As discussed in Chapter 2, determination of wind forces presents
only a part of the picture regarding wind erosion. The physical character-
istics of the ground cover which the wind travels must also be considered
in evaluating the potential for erosion. The surface roughness, moisture
content and cohesiveness of the soils; quantity, type and arrangement of
the vegetation or crops grown; and the "fetch", or distance across the
field that the wind can move without an obstruction changing its velocity.
-------
4-11
Item
Jan.
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Kingman, Ariz.
(Mar. 1943 - June 1945)
Magnitude
Direction
Preponderance
150
45
2.9
244
67
1.7
337
67
2.6
256
45
2.8
280
45
2.7
329
45
3.6
225
45
2.4
181
45
2.9
162
45
1.9
98
45
1.5
83
45
2.0
66
90
1.6
Phoenix, Ariz.
(May 1950 - Apr. 1955)
MT&gTiitud*?
Direction
Preponderance
45
180
1. 5
101
157
1.4
74
158
1. 6
93
180
1. 7
89
113
1.4
62
135
1.5
131
90
1. 5
97
135
1.7
76
112
1.7
34
90
1.6
29
90
1.0
38
113
1. 4
Prescott, Ariz.
(Jan. 1953 - Jan. 1963)
Magnitude
Direction
Preponderance - - - -
69
68
1.7
128
68
1. 4
194
45
1.7
236
67
2.0
242
67
2.7
204
45
2.3
103
45
1.9
75
67
1.6
88
67
2.0
85
68
2. 1
76
68
2. 2
57
68
1. 5
Tucson, Ariz.
(Sept. 1952 - Jan. 1963)
Magnitude - *
Direction
Preponderance -_ - -
93
157
2.6
82
158
1.7
101
158
1.6
121
180
1. 4
132
22
1.7
91
158
1. 2
96
157
1. 5
63
157
1.6
70
157
2. 1
107
157
2.3
106
157
3.4
87
157
2.6
Yuma, Ariz.
(Sept. 1952 - Jan. 1963)
Magnitude
Direction -
Preponderance -
62
90
2.6
90
90
2. 1
89
113
1.5
111
157
1. 5
108
135
1.7
107
113
2.2
139
113
3.0
114
113
2. 5
43
112
1.9
45
113
1. 4
62
90
2.4
59
90
2.7
Arcata, Calif.
(Dec. 1949 - Nov. 1958)
Magnitude -
Direction -
Preponderance
159
135
2.3
154
135
2.8
183
135
3.3
172
135
3.9
192
135
4. 4
140
135
6. 6
80
135
6. 9
54 53
135 135
5. 0 3. 6
81
114
2. 1
93
135
3. 1
126
135
2.5
Bishop, Calif.
(Jan. 1948 - Jan. 1957)
\Iagnitude
Direction
Preponderance
170
90
4, 1
234
90
4.0
409
90
3.2
299
90
2.6
305
90
2.0
256
90
2. 4
170
112
2. 1
176
90
2.3
175
90
2. 5
242
90
3. 6
222
90
5. 7
161
90
3. 9
Blythe, Calif.
(Aug. 1942 - May 1944)
Magnitude
Direction
Preponderance
110
90
2.3
108
90
2. 4
172
90
2.2
132
45
2.3
226
90
1. 4
216
45
2. 1
136
90
1.9
166
90
3.9
59
90
1.8
103
67
1.9
127
90
4.2
90
113
1.9
Direction given in degrees measured counterclockwise with East 0°
North 90°, West 180°, and South 270°
TABLE 4-2 - Relative Magnitude, Prevailing Wind Erosion Direction, and
Preponderence of Wind Erosion Forces In Selected Areas.
(From Reference No. 4-7).
-------
4-12
CITED REFERENCES
4-1. U. S. Department of Agriculture, Soil Conservation Service
"National Engineering Handboook, Section, Hydrology". 1972
4-2. U. S. Environmental Protection Agency and Department of
Agriculture "Control of Water Pollution From Cropland - Vol. I,
A manual for guideline development, " EPA-600/2-75-026(a),
November, 1976.
4-3. "Control of Water Pollution From Cropland - Volume
II - An Overview, " EPA-600/2-75-026(b), June 1976.
4-4. U.'S. Environmental Protection Agency, "Methods For Identifying
and Evaluating The Nature and Extent of Nonpoint Sources of
Pollutants, " EPA-430/9-73-014, October 1973.
4-5. U.S. Department of Agriculture, Agricultural Research Service
"Predicting Rainfall - Erosion Losses From Cropland East of
The Rocky Mountains, " Agriculture Handbook No. 282, May, 1965.
4-6. -, Soil Conservation Service "Procedure for Determining
Rates of Land Damage, Land Depreciation and Volume of Sediment
Produced By Gully Erosion, " Technical Release No. 32. July, 1966.
4-7. - , Agricultural Research Service, in cooperation with the
Kansas Agricultural Experiment Station, "Wind Erosion Forces In
The United States and Their Use in Predicting Soil Loss, " Agricultural
Handbook No. 346. April, 1968.
-------
A-l
APPENDIX A
ABSTRACTS OF BMP HANDBOOKS
The documents described in this Appendix represent the most current
efforts by EPA to establish the State-of-the-Art of various agricultural
activities and to discuss management practices pertinent to water quality
management planning. A few of these handbooks have been printed and are
available from the sources indicated. The others will be available as listed.
To obtain single copies, write to the address indicated on the last page
of the Appendix.
-------
A-2
ABSTRACTS
a) ''Control of Water Pollution from Cropland", Volume I.
A manual for guideline development, November. 1975.
EPA-600/2-75-026a":
The purpose of the manual is to provide information to
individuals or agencies charged with developing plans for the
control of reduction of pollution from nonpoint agricultural
sources. Information on the sources, causes, and potentials
of sediment, nutrient, and pesticide losses from cCopland is
dealt with in depth, as is information on selecting cropping
systems, tillage practices, and other measures that may be
necessary to control pollutants. The information presented
should be useful in selecting the control measures that are
appropriate for the special conditions imposed by the climate,
soils, topography, and farming practices of a particular land
area. The manual also presents procedures for estimating the
cost of various control practices at the farm level. The
regional and national economic impacts of certain nonpoint
pollution control methods are also discussed. Handbook Source 1,
2, 3, 4.
(2) "Control of Water Pollution froni Cropland", Volume II,
An Overview, February, 1977. EPA-6UU/2-75-026b.
The ultimate decision as to whether agriculture s
contributing to pollution of particular water bodies to su h
an extent that active control measures are required rests with
State or local authorities. To assist these officials in
reaching this decision and in choosing appropriate controls,
the Federal Water Pollution Control Act Amendments of 1972,
Public Law No. 92-500, specify that the Administrator of the
Environmental Protection Agency shall, in cooperation with
other agencies, provide guidelines for identifying and
evaluating the nature and extent of nonpoint sources of
Pollutants. This two-volume document on control of potential
water pollutants from cropland was written by scientists of
the U. S. Department of Agriculture in response to this pro-
vision of the Act and at the request of the Environmental
Protection Agency. Volume I is a User's Manual for guideline
development. Here in Volume II we will review some of the
basic principles on which control of specific pollutants is
founded, provide supplementary information, and present some
of the documentation used in Volume I. Handbook Source 1, 2,
3, 4.
(3) "A Manual for Control of Pollutants Generated by Irrigated
Agriculture", May, 1971T'
The manual will provide guidance in the evaluation of
(1) water quality problems resulting from irrigation return
flow, and (2) solution to those problems. It will provide the
-------
A-3
necessary background for evaluation of the applicability of
"best management practices" (BMP's) at the local and regional
level. The manual presents: (I) background information on
the technology involved; (2) methods of evaluation of water
quality problems; (3) methods of evaluating alternative
management practices; (4) review of problems and solutions
being developed in selected areas of the western United States.
The presentation will be directed towards regional water
quality planning agencies, soil and water conservation
agencies, local and regional government officials, irrigation
districts, and individual irrigators. Handbook Sources 3 and 5.
(4) "Salinity Management in Irrigated Agriculture". June, 1978.
This project is designed to produce a manual of best management
practice for the control of salinity from irrigated agriculture in
the western U. S. It is to be based upon structural and non-
structural technology which has been demonstrated effective in
reducing salt loading to river systems. Educational materials will
also be developed to assist in the dissemination of this information
to the areawide planners and other user groups. Handbook Source
3 and 5.
(5) "A Manual for -- Evaluating Land Applications of Livestock and
Poultry Residue", December 1977.
The objectives of this manual are to:
1. Provide basic information to enable planners to reduce or
control nonpoint pollution from livestock and poultry
residue land application systems.
2. Provide systematic procedures for evaluating current and
future livestock and poultry residue land application systems
in terms of agronomic benefit and/or pollution potential.
3. Provide sufficient information to enable planners to
integrate the numerous variables into a land application
system which makes beneficial use of livestock and poultry
residues.
The objectives of this manual will be achieved when the evaluation
procedures are used by groups of specialists charged with developing
specific practices for state and local areas. Specialists include farmers,
engineers, agronomists, hydrologists, soil scientists and economists com-
bining to integrate the numerous variables into the best management system.
This manual provides information to individuals or agencies charged
with developing plans for controlling or reducing pollution caused by
disposal of livestock and poultry residues on land if that is_ a problem
-------
A-4
in a particular instance. Included are guidelines for choosing the most
appropriate methods for particular residues, and individual fields, and
cropping practices. Handbook Source 2, 3, and 5.
(6) "Environment Protecting Concepts of Beef Cattle Feedlot Wastes
Management", July 19757
The function of this manual is to serve as a guide to insure
consideration and incorporation of pertinent environmental
pollution controls in the design and operation of beef cattle
feedlots. It has been designed to serve as a reference source
for the more detailed information contained in published literature
on feedlot design and operation. In addition, the precepts
presented in this manual are applicable to other segments of the
animal industry. Handbook Source 3 and 5.
(7) "A Manual On: Evaluation and Economic Analysis of Livestock
Waste Management Systems", January 1978
The waste management systems suitable for dairy, beef,
swine, sheep, and poultry facilities differ from region to
region in the United States. This manual identifies the
principal regional, environmental, engineering, and economic
constraints on alternative waste systems. The objective is,
(1) to provide a manual on cost/effective livestock manage-
ment systems to control pollution from non-NPDES facilities,
excluding cattle on range, and (2) to identify and evaluate
"no-discharge" management systems.
The scope of the manual will include management of
runoff, solid and airborne wastes from non-NPDES animal pro-
duction facilities, the Manual is prepared for use by farmers,
farm planners, Extension personnel, 208 planners, and other
planners and decision makers. Handbook Source 2, 3, and 5.
(8) "Environmental Impact Resulting From Unconfined Animal Production'
January. 1978.
This report presents an evaluation of the environmental
effects arising from production of farm animals in unconfined
systems. The differentiation between confined and unconfined
production systems is that the wastes generated in a confined
system is subject to handling while that in an unconfined
system is not. In this report the differentiation between
unconfined and confined systems is the same as that for point
and nonpoint sources. And, an unconfined system is the same
-------
A-5
as a grazing system (one in which livestock have access to
pasture, range or woodland and utilize the associated forage
as a principal source of feed).
Farm animals that are produced in unconfinement are
cattle (both dairy and beef), sheep, hogs (primarily sow
operations) and goats. Commercial or farm production of
poultry (chickens, turkeys, duck) utilize confinement
systems exclusively (and, poultry wastes require management
as point sources). While horses are sometimes kept in un-
confined systems, they pleasure animals rather than farm
animals and, thus, are not a direct subject of this report.
Handbook Source 2, 3, and 5.
(9) "Nitrogen Management In Irrigated Agriculure" - A State-
of-the-Art Review - May, 1978.
A state-of-the-art review of what is now known with
respect to nitrogen management in irrigated agriculture.
Handboo Source 3, 4, and 5.
-------
A-6
HANDBOOK SOURCES
(1) U. S. Environmental Protection Agency
Agriculture and Nonpoint Source Management Division (RD-682)
Washington, D. C 20460
(2) U. S. Department of Agriculture
ARS Information - Room 343A
Federal Center Building - No. 1
Hyattsville, Maryland 20782
(3) National Technical Information Service
5285 Port Royal Road
Springfield, Virginia 22151
(4) Superintendent of Documents
U. S. Government Printing Office
Washington, D. C 20402
(5) Robert S. Kerr
Environmental Research Laboratory
Ada, Oklahoma 74820
-------
B-l
APPENDIX B
FEDERAL REGISTER,
March 18, 1976
-------
B-2
THURSDAY, MARCH 18, 1976
PART III:
ENVIRONMENTAL
PROTECTION
AGENCY
STATE PROGRAM
ELEMENTS NECESSARY
FOR PARTICIPATION IN
THE NATIONAL
POLLUTANT DISCHARGE
ELIMINATION SYSTEM
Concentrated Animal Feeding Operations
-------
B-3
11458
RULES AND REGULATIONS
Title 40—Protection of Environment
CHAPTER I—ENVIRONMENTAL
PROTECTION AGENCY
[PRL 503-2]
NRDC v. Train [396 P. Supp. 1393, 7
ERG 1881 (DD.C. 1975) ]. Although EPA
Is proceeding with the appeal of this
case, the Agency Is required to proceed
with the promulgation of thes» regula-
PART 124—STATE PROGRAM ELEMENTS tions. For a detailed history of the de-
NECESSARY FOR PARTICIPATION iN velopment of the proposed regulations
THE NATIONAL POLLUTANT
CHARGE ELIMINATION SYSTEM
DIS-
see the preamble to the November 20,
1975, publication.
At the time of the November 20, 1975,
publication of the proposed regulations
EPA solicited comments on all aspects
of the regulations and received more than
On November 20, 1975, the Environ- 50 comments in response from industry
mental Protection Agency (EPA) pro- groups, educational Institutions, environ-
posed regulations for applying the Na- mental organizations, federal state and
tional Pollutant Discharge Elimination local agencies and interested persons.
PART 125—NATIONAL POLLUTANT
DISCHARGE ELIMINATION SYSTEM
Concentrated Animal Feeding Operations
«— «*- »-e been carefully con-
(40 FR 54182). These regulations were sidered and several changes have been
proposed in accordance with the June 10, made to the proposed regulations in re-
1975. court order issued following the sponse to the suggestions made. The most
decision of the Federal District Court for important of these changes are dla-
the District of Columbia in the case of grammed as follows and discussed below.
BASIC STRUCTURE OF PEEDLOT PROGRAM
PROGRAM PROPOSED IN NOV. S REGULATIONS
Feedlots with 1,000 or more
animal units Feedlots with, less than 1,000 animal units
Permit required for all feed- Permits required lor f eedlots. with :
lota with discharges1 of (1) Discharges1 of pollutants through a manmade con-
pollutants. veyance, or
(2) Discharges1 of pollutants Into waters traversing the
confined area.
'Feedlot not subject to requirement to obtain permit If discharge occurs only in the
event of a 25-yr., 24-b., storm event.
NOTE. — All feedlota subject to a case-by-case designation requiring an Individual permit.
Basic ttr-icture of feedlot program — program promulgated today
Feedlots with 1,000 Fetdlots with less than 1,000 but with 300 or Feedlots wit i less than 300 animal units
or more animal units more animal units
Permit required for all
feedtots with dis-
charges ' of pollut-
ants.
1'crmlt. required if feedlot—
1. Discharge' pollutants through a
manmade conveyance, or
2. Discharges > pollutants Into waters
passing through or coming Into di-
rect contact with animals In the
confined area.
rerdlots subject to case-by-case designation
requiring an individual permit only after
oislte Inspection and notice to the owner
or opvratoi.
No permit required (unless ease-by-caj
designation as provided below).
Case-by-case designation only if feed lot—
1. Discharges pollutants through a man-
made conveyance, or
2. Discharges pollutants into waters pass-
Ing through or coming into direct
contact with the animals in the con-
fined area: and
After onsite inspection, written notice Is
transmitted to the owner or operator.
' Firdlol not subject to requir"menl to olilain nwniit if discharge occurs only in the event of a 25-yr. i l-li storm
event. •
(1) As seen in the diagram above, a
lower level cutoff number has been added.
Under the program established today,
permits are required from feeding opera-
tions with less than 1,000 but with 300
or more animals only for those operations
which have discharges of pollutants (a)
through a man-made conveyance or (b)
directly into navigable waters which pass
through the confined area. For opera-
tions with less than 300 head, no per-
mit application is required unless there
Is an onsite inspection of the operation
and the owner or operator is notified in
writing that such application is required.
(2) As was pointed out by numerous
commenters, the statement by Senator
Edmund Muskie regarding feedlota
covered by the permit program provided
general guidance rather than a definitive
statement of criteria. Although the
Agency proposed to adopt the numbers
suggested by Senator Muskie, the upper
level cutoff numbers established in the
July 5,1973, promulgation (3d FR 18000)
of feedlot permit requirements are the
basis for the upper levels established
today. The numbers published in July
1973 and hereby affirmed require permits
for operation with more than 1000 beef
cattle; 700 dairy cattle, 2,500 swine;
10,000 sheep; 55,000 turkeys; 100,000
chickens (if the operation has continu-
ous overflow watering); 30,000 chickens
(if the operation has a liquid manure
handling system); 5,000 ducks; and 500
horses. (See 40 CPR 55124.11 (h)(l),
125.4(j) (1), 412.10 and 40 FR 54182.) As
pointed out by the commenters the
earlier numbers were much better justi-
fied by studies and data than were the
numbers set forth in Senator Muskie's
guidance. Also, maintaining the same
upper level numbers will minimize dis-
ruption and confusion among those feed-
lot operators currently subject to the
permit program.
(3) For feeding operations with less
than 300 animal units, only those oper-
ations which (a) have streams passing
through the confined area, or (b) have
direct discharges to navigable waters
will be subject to the possibility of being
designated as a concentrated animal
feeding operation on a case-by-case basis
by a State pollution control Director or
the EPA Regional Administrator. No
feeding operation with less than 300 ani-
mal units will be required to apply for
or obtain a permit unless it meets one
of the above criteria, and, following an
onsite inspection, the owner or operator
has been individually notified in writing
that a permit application is required.
RESPONSE TO COMMENTS ON THE PROPOSED
PROGRAM
Comments received in response to the
proposed November 20, 1975, regulations
have been entered into the record of the
development of these regulations and are
available for public inspection at EPA.
All comments received have been care-
fully considered and many have been
adopted or substantially satisfied by edi-
torial changes, deletions or additions to
the regulations. Several of the major
comments and their disposition are dis-
cussed below.
1. The definition of "animal feeding
operation" [
-------
there must be a "discharge of a pollutant"
from the point Bouro* Into "navigable
waters." If there 1» no discharge from a par-
ticular operation which lg a point source,
there la no need for a permit. • • • [Tine
proposed regulations provide that no permit
Is required for any concentrated animal
feeding operation which discharges pollut-
ants only In the event of a 26 year, 24 hour
rainfall event. In addition, nlthough there
may be a discharge of a pollutant from a
point source, no permit Is required If such
a discharge does not reach navigable waters.
2. The definition of "concentrated ani-
mal feeding operation"'[(a) (2) ]. Many
comments were received suggesting that
this critical term be clarified in several
ways.
'a) One commenter pointed out that
the word "concentrated" connotes a
large number of animals confined in a
relatively small area, and Indicated that
part of the regulations were inconsistent
with this plain meaning of the term. The
parts of the definition of "concentrated
animal feeding operation" beginning
with the words "[without regard to the
numbers * * * of animals confined"
present a meaning contrary to the ordin-
ary use of the word "concentrated." In
order to eliminate this contradiction, ad-
ditional cutoff numbers have been added
to the definition. These numbers would
indicate the size of the animal feeding
operations which are not, as a general
matter, "concentrated" and, therefore,
for which, lacking a specific written de-
termination (following a field Inspection;
see further below) to the contrary, no
permit would be required. This de mini-
mis lower level general cutoff is consist-
ent with the decision in NRDC v. Train
which states that not everv "ditch, water
bar or culvert" is "meant to be a point
source under the Act [Federal Water
Pollution Control Act]" (7 ERC 1881 at
1887).
In addition, in response to comments
concerning combinations of animals for
confined operations, the term "animal
unit" Is re-established consistent with
the term as used in the July 1973 pub-
lication. This term is defined and added
to the list of definitions for this section.
(b) Many commenters asked for a
definition of "measurable wastes." Be-
cause it implied the Imposition of costly
and time-consuming monitoring require-
ments, the term "measurable wastes" has
been deleted. The more consistent term
"pollutants," which is defined in sertion
502(6) of the Federal Water Pollution
Control Act (Public Law 92-500; 33
U.S.C. 1251 et seq; the Act), has been
inserted instead.
(c) Many oommenters also noted the
need to clarify the term "navigable wa-
ters." This term is fully explained and
interpreted in detail at 40 CFR 125.1 (p).
(d) Several commenters suggested
that the criterion related to waters which
"traverse" the operation be clarified. Ac-
cordingly, this criterion has been rewrit-
ten without the word "traverse" In order
to make clear that this criterion relates
to waters which come Into contact with
',he animals confined In the operation.
B-4
RULES AND REGULATIONS
(e> Three commenters pointed out
that the words concerning direct dis-
charge were ambiguous in that wastes
may be discharged from an animal feed-
ing operation but may not reach navi-
gable waters. These" regulations concern
only those discharges of animal wastes
that enter navigable waters. Thus for
example, if discharges leave the feeding
operation but do not reach navigable wa-
ters because of filter strips or other waste
management techniques, no permit is
required.
(f) Some comments were received con-
cerning the cutoff numbers used in the
definition. The majority of these com-
ments accepted the numbers and urged
that they be adopted. One comment sug-
gested higher numbers and a few com-
ments suggested lower numbers. As dis-
cussed in more detail above, however, the
numbers established In the previous
feedlot regulations, published In July
1973, have been reinstated.
(g) Several comments were received In
reference to the provision concerning the
25 year, 24 hour storm event. Half of
these comments suggested that a 10 year,
24 hour storm event be substituted for
the criterion in the proposed regulations.
However, consistent with data used In
the development of the July 1973 pro-
mulgation indicating that such criterion
was rational and feasible for all feedlots
with 300 or more animal units, the 25
year, 24 hour storm criterion has been
retained.;
3. The definition of "man-made" [(a)
(3) ]. This definition has been amended
to reflect four comments recommending
a slight expansion of the term.
4. Application for a permit f(b)(l) and
(2) 1. Comments were received indicating
that the time period between the appli-
cation date of March 10, 1977, and the
implementation deadline In the Act of
July 1, 1977, was Inadequate to enable
owners and operators to construct pollu-
tion control devices. In order to alleviate
this problem, the deadline for permit ap-
plications has been changed to Septem-
ber 1, 1976. This shortened deadline will
not be unduly burdensome because the
Short Form B on which the permit ap-
plications are to be filed is very brief.
(The application fee for the Short Form
B is *10). The earlier deadline also pro-
vides for more time to comply with the
procedural elements of permit issuance,
including notice and opportunity for a
hearing.
5. Case-by-case designation [(c)].
Several commenters pointed out a need
to specify the criteria listed In this sec-
tion and to narrow the discretion of the
Director or Regional Administrator to
designate an animal feeding operation as
concentrated and therefore requiring a
permit. This section was included in the
regulations to provide for flexibility in
State pollution control programs which
was urged by scores of participants In
the public meetings held on this subject.
To further define the criteria would de-
feat the purpose of this provision to pro-
vide for site-specific determinations.
11459
However, it Is Intended that the Di-
rector or Regional Administrator should
exercise their discretion with respect to
facilities having pollution potential.
Thus, for operations smaller than 300
animal units only those which (a) have
streams passing through the confined
area or (b) have direct discharges to
navigable waters are subject to this case-
by-case designation.
In exercising his discretion, the Di-
rector or Regional Administrator will
designate a concentrated animal feeding
operation only after an onsite Inspection
and determination that the operation
should and could be regulated under the
permit program. In addition, before an
application is required, the owner or
operator of the feedlot will be notified
of the application requirement. As with
past experience, it Is anticipated that the
Director or Regional Administrator
would exercise this discretion only in ex-
ceptional cases.
It bears repeating that owners or oper-
ators of point sources are not required to
apply for and obtain pollution discharge
permits if there is no discharge of pol-
lutants from such point sources into
navigable waters. Thus, totally enclosed
systems, such as many poultry opera-
tions, without discharges Into navigable
waters are not subject to the permit re-
quirements regardless of their size. Also,
no permits would be required from
owners or operators of operations which
recycle all pollutants to the land, or
which absorb all animal wastes In filter
strips or otherwise prevent such wastes
from reaching navigable waters. Thus,
any feedlot owner or operator who uses
alternate management techniques and
prevents all discharges from reaching
navigable waters would not have to
obtain a permit
Because of the importance of promptly
making known to other Federal Agencies,
States, dischargers, environmentalists
and other interested persons the content
of these regulations and because of the
need to implement this program
promptly, the Administrator finds good
cause to declare these regulations effec-
tive immediately upon publication.
No Inflationary Impact Statement is
required by Executive Order 11821 for
these regulations since the economic ef-
fects will not exceed the criteria estab-
lished by EPA and approved by the Office
of Management and Budget for the
preparation of such statements.
Dated: March 10, 1976.
RUSSELL E. TRAIN,
Administrator.
Part 124 of Title 40 of the Code of
Federal Regulations, setting forth State
program elements necessary for partici-
pation in the National Pollutant Dis-
charge Elimination System, is amended
as follows:
§ 124.1
Subpart A—General
[Amended]
1. Section 124.1 is amended by deleting
subsection (u) and by reletterlng subsec-
tion (v) to (u).
FEDERAL UCISTEI, VOL. 41, NO. 34—THURSDAY, MARCH 18; 1976
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11460
Subpart B—Prohibition of Discharges of
Pollutants
§ 124.11 [Amended]
2. Paragraph (h) of 5 124.11 Is
amended by deleting paragraphs (h)
(1) and (2i; by renumbering para-
graphs (h) (3), (41, and <5) to ih) (2),
(3), and (4) respectively; and by adding
a new paragraph (h> U> as follows: "(1)
Discharges from concentrated animal
feeding operations as defined in § 124.-
82(a)i2K"
Subpart I—Disposal of Pollutants Into
Weils
§ 124.80 Redesicnaled 124.81.
3. Subpart I of Part 124 is amended
by deleting the title "Disposal of Pol-
lutants into Wells" and by adding a new
title "Special Programs," and by re-
numbering 5 124.80 to 124.81.
4. Subpart I of Part 124 is amended
by adding a new § 124.82, Concentrated
Animal Feeding Operations, as follows:
§ 124.82 Concentrated Animal Feeding
Operations.
(a) Definitions.
For the purpose of this section:
(1) The term "anima! feeding opera-
tion" means a lot or facility (other than
an aquatic animal production facility)
where the following conditions are met:
(i) Animals have been, are or will be
stabled or confined and fed or main-
tained for a total of 45 days or more in
any 12 month period, and
(ii) Crops, vegetation, forage growth
or post-harvest residues are not sus-
tained in the normal growing season
over any portion of tne lot or facility.
Two or more animal feeding opera-
tions under common ownership are
deemed to be a single animal feeding op-
eration If they are adjacent to each other
or If they utilize a common area or sys-
tem for the disposal of wastes.
(2) The term "concentrated animal
feeding operation" means an animal
feeding operation which meets the cri-
teria set forth in either (a) (2) (i) or (ii)
below:
(i) More than the numbers of animals
specified in any of the following cate-
gories are confined:
(a) 1,000 slaughter and feeder cattle,
(b) 700 mature dairy cattle (whether
milked or dry cows),
(c) 2,500 swine weighing over 55
pounds,
(d) 500 horses,
(e) 10,000 sheep or lambs,
(/) 55,000 turkeys,
<<7) 100,000 laying hens or broilers (if
the facility has continuous overflow
watering),
(h) 30,000 laying hens or broilers (if
the facility has a liquid manure handling
system),
~ (i) 5,000 ducks, or
(?) 1,000 animal units: or
(ii) More than the following numbers
and types of animals are confined:
(a) 300 slaughter or feeder cattle,
B-5
RULES AND REGULATIONS
(b) 200 mature dairy cattle (whether
milked or dry cows),
(c) 750 swine weighing over 55 pounds,
(d) 150 horses,
above shail be designated as a concen-
trated animal feeding operation unless
such animal feeding operation meets
either of the following conditions:
(6) Pollutants are discharged into
navigable waters through a man-made
ditch, flushing system or other similar
man-made device; or
(7) Pollutants are discharged directly
into navigable waters which originate
outside of and pass over, across, through
or otherwise come into direct contact
with the animals confined in the opera-
tion.
In no case shall a permit application be
required from a concentrated animal
feeding operation designated pursuant
to this section until there has been an
onsite inspection of the operation and a
determination that the operation should
and could be regulated under the permit
program. In addition, no application
shall be required from an owner or op-
erator of a concentrated animal feeding
operation designated pursuant to this
section unless such owner or operator is
notified in writing of the requirement to
apply for a permit.
Part 125 of Title 40 of the Code of
Federal Regulations, setting forth poli-
cies and procedures for the Environ-
mental Protectinn Agency's administra-
tion of its role in the National Pollutant
Discharge Elimination System, is
amended as fellows:
Subpart A—General
§ 125.1 [Amended]
1. Section 125.1 is amended by delet-
ing paragraph (ii) and by relettering
paragraph (jj) to (ii).
§ 125.4 [Amended]
2. Paragraph
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§ 125.51 Concentrated Animal Feeding
Operations.
(a) Definitions.
For the purpose of this subpart:
(1) The term "animal feeding opera-
tion" means a lot or facility (other than
an aquatic animal production facility)
where the following conditions are met:
or (ii)
below:
(i) More than the numbers of animals
specified in any of the following catego-
ries are confined:
(a) 1,000 slaughter and feeder cattle,
(b) 700 mature dairy cattle (whether
milked or dry cows).
(c) 2,500 swine weighing over 55
pounds,
(d) 500 horser,,
(e) 10.000 sheep or lambs,
(/) 55,000 turkeys,
(g) 100,000 laying hens or broilers (if
the facility has continuous overflow
watering),
Pollutants are discharged directly
into navigable waters which originate
outside of and pass over, across, through
or otherwise come into direct contact
with the animals confined in the opera-
tion.
Provided, however^ that no animal feed-
ing operation is a concentrated animal
feeding operation as denned above if such
animal feeding operation discharges only
in the event of a 25 year, 24 hour storm
event.
(3) The term "animal unit" means a
unit of measurement for any animal
feeding operation calculated by adding
the following numbers: the number of
slaughter and feeder cattle multiplied
by 1.0, plus the number of mature dairy
cattle multiplied by 1.4,'plus the number
of swine weighing over 55 pounds multi-
plied by 0.4, plus the number of sheep
multiplied by 0.1, plus the number of
horses multiplied by 2.0.
(4) The term "man-made" means con-
structed by man and used for the pur-
pose of transporting wastes.
(b) Application for Permit. (1) Any
person discharging or proposing to dis-
charge pollutants from a concentrated
animal feeding operation, who has not
already done so, shall file an application
with the Regional Administrator by Sep-
tember 1, 1976.
(2) fii Each application must be filed
on a Short Form B and completed in
accordance with the instructions pro-
vided with such form.
(ii) In addition to the information re-
quired in the Short Form B the Regional
Administrator may require any applicant
to submit such other appropriate infor-
mation as the Regional Administrator
deems necess'ary to proceed with the is-
suance of the permit.
(c) Case-by-case Designation of Con-
centrated Animal Feeding Operations.
Notwithstanding any other provision of
11461
this section, the Director or the Regional
Administrator may designate as a con-
centrated animal feeding operation any
animal feeding operation not otherwise
falling within the definition provided in
5 125.51 (a) (2) above. In making such
designation the Director or Regional Ad-
ministrator shall consider the following
factors:
(1) The size of the animal feeding op-
eration and the amount of wastes reach-
ing navigable waters;
(2) The location of the animal feed-
ing operation relative to navigable
waters;
<3) The means of conveyance of
animal wastes and process waste waters
into navigable waters;
(4) The slope, vegetation, rainfall, and
other factors relative to the likelihood or
frequency of discharge of animal wastes
and process waste waters into navigable
waters; and
(5) Other such factors relative to the
significance of the pollution problem
sought to be regulated.
Provided, however, that no animal feed-
ing operation with less than the numbers
of animals set forth in (a) (2) (ii> above
shall be designated as a concentrated
animal feeding operation unless such
animal feeding operation meets either of
the following conditions:
(6) Pollutants are discharged into
navigable waters through a man-made
ditch, flushing system or other similar
man-made device; or
(1) Pollutants are discharged directly
into navigable waters which originate
outside of and pass over, across, through
or otherwise come into direct contact
with the animals confined in the
operation.
In no case shall a permit application
be required from a concentrated animal
feeding operation designated pursuant to
this section until there has been an on-
site inspection of the operation and a
determination that the operation should
and could be regulated under the per-
mit program. In addition, no application
shall be required from an owner or oper-
ator of a concentrated animal feeding
operation designated pursuant to this
section unless such owner or operator te
notified in writing of the requirement to
apply for a permit.
[FB Doc.76-7664 Filed 3-17-76;8:45 am|
FEDERAL REGISTER, VOL. 41, NO. 54—THURSDAY, MARCH IS, 1976
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APPENDIX C
BEST MANAGEMENT PRACTICES
STATEMENT
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BEST MANAGEMENT PRACTICES
AGRICULTURAL NONPOINT SOURCES
WATER POLLUTION
Agricultural nonpoint sources are a broad category covering all crop
and animal production activities. Crop production includes both
irrigated and non-irrigated production, such as row crops, close
grown crops, orchards and vineyards, and fallow land temporarily
out of production. Animal production includes such systems as pasture
and rangeland grazing, semiconfined feeding and grazing, and con-
centrated animal feeding operations.
Introduction
This guidance is intended to provide information regarding the
control of pollution from a agricultural nonpoint sources, and to
supplement information regarding the control of agricultural discharges
regulated under the requirements of NPDES. Agricultural production
activities provides, on a national scale, significant sources of pollutants
which reach both surface and ground waters. These may be either
point sources or nonpoint sources, or combinations of the two.
Description of Agricultural Activities
Agricultural nonpoint sources are the crop and animal production
systems that result in diffuse runoff, seepage, or percolation of
pollutants to the surface and ground waters. There are a number of
different activities within each of the systems that may cause water
pollution. The runoff, seepage or percolation of pollutants generated
by the activities are strongly dependent on climatic events such as rain-
fall and snowmelt. In general, they are intermittent and do not represent
a continuous discharge. The nature of the pollutants depends on the
particular activities underway at the time of the climatic events. Both
the nature and amount of pollutants are also dependent on other factors
such as soil types, topography, crop and animal types, and crop and
animal production methods.
Crop Production
There are five general categories of activities associated with crop
production which can produce the potential for nonpoint source pollution:
1. The disturbance of the soil by tillage or compaction by
machinery.
2. The alteration of natural vegetative patterns by substituting
crop plants for natural vegetation or leaving the soil without vegetative
cover.
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3. The increase in available nutrients, over the quantity available
through natural cycles, by the application of fertilizers.
4. The introduction of chemical compounds not found in significant
quantities under natural conditions such as by the application of
pesticides.
5. The application of surface or ground waters for the purpose of
irrigating crops.
Animal Production
There are three general categories of activities associated with
animal production which can produce the potential for nonpoint source
pollution:
1. Concentration of animals (and their wastes) in a particular
location for an extended period of time such as at feeding areas.
2. Overgrazing of range and pasture lands that removes vegetative
cover from the land.
3. Concentration of animals instreams or along stream banks
in such numbers as to cause disturbance of the stream bottoms or banks,
or result in direct deposit of manure into streams.
Identification of Pollutants
Six general types of nonpoint source pollutants that may result from
activities associated with agricultural production systems are:
1. Sediment: Sediments, by volume, are the most serious
pollutants resulting from agricultural production. They include prin-
cipally mineral fragments resulting from the erosion of soils but may
also include crop debris and animal wastes. Sediments can smother
organisms in water bodies by forming bottom blankets, interfere with
the photosynthetic processes by reducing light penetration, and act as
carriers of nutrients and pesticides. Deposits also may fill reservoirs
and hinder navigation.
2. Nutrients: Nutrients, above the natural background levels of an
area may result from fertilizer applications and animal wastes. Soluble
nutrients may reach surface and ground water through runoff, seepage,
and percolation. Ions may be adsorbed on soil particles and reach surface
water through sedimentation processes. Nutrients may also reach surface
water by direct washoff of animal wastes and recently applied fertilizer.
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Excessive nutrients can lead to imbalance in the natural nutrient cycles
and cause eutrophication. In some cases, excessive nutrients can be
a health hazard.
3. Pesticides: Pesticides which are applied in the agricultural
production unit may be insoluble or soluble. The entrance of
pesticides into the surface or ground waters follows approximately
the same patterns as nutrients. Pesticides may cause acute
toxicity problems in the water bodies or insidious toxicity problems
through the entire food chain.
4. Organic Materials: Animal wastes and crop debris are the
principal organic pollutants that result from agricultural production.
They may reach surface waters through direct washoff,
or, in their soluble form, reach both surface and ground waters
through runoff, seepage or percolation. The organic materials place
an oxygen demand on the receiving waters during their decomposition.
In addition, they may lead to other problems such as tastes, odors,
color, and nutrient enrichment.
5. Salinity (TDS): The necessity of leaching to remove, or prevent
the damaging accumulation of salts in the root zone of plants has the
potential of inducing subsequent quality problems in both surface and
ground waters if agricultural waters are not properly managed. Percol-
ating water may reach ground water through further deep percolation,
or move laterally into surface water bodies. The problem becomes
more pronounced v/hen the applied irrigation water initially contains
dissolved solids which will become more concentrated as the
plants remove water for their use. Severity of pollution depends not
only on the nature of the receiving waters but also on the nature of
the uses of the receiving waters.
6. Microorganisms: Any potential disease-causing micro-
organisms (pathogens) in water are a matter of concern to the health
and safety of the water users. Animal wastes are the principal source
of pathogenic microorganisms resulting from agricultural production.
Pathogens reach the water bodies through the same routings as
the animal wastes.
Basis For Best Management Practices Development
Best Management Practices for agricultural production are the
most practical and effective measure or combination of measures, which
when applied to the agricultural management unit, will prevent or reduce
the generation of pollutants to a level compatible with water quality goals.
They often enhance the productivity of the soil as well as control pollution.
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Because of the variability in production methods, crops and
animals, soil types, topography, climate, etc., the BMP for any specific
agricultural management unit or area will vary. The selection of Best
Management Practices for a particular agricultural management unit or
area is a complex process. Any measure or combination of measures
applied to an agricultural management unit or area which will achieve
water quality goals is a potential BMP. However, the measures are
generally the type that are incorporated into a soil and water con-
servation plan as developed by a landowner or land user, with the
assistance of a conservation district and/or the Soil Conservation Service,
Extension Service, Forest Service, and others.
The principal emphasis should be placed on measures that will
prevent or control the runoff, seepage or percolation of pollutants
from crop or animal production management units. Preventive measures
must be fully integrated into the total production management
system of the agricultural management units. In essence, the soils,
nutrients and pesticides should be kept on the land where they perform
their intended agricultural function.
Because of the widespread nature of sediment runoff, erosion control
measures should be a principal means of controlling pollution from
each agricultural management unit. Control of erosion not only will prevent
soils from leaving the land, but also will materially reduce the nutrients
and pesticides that reach the nation's waters adsorbed to soil particles.
Where necessary, to further prevent or reduce the entrance of sediments
into water bodies, supplemental measures such as debris and sediment
retention basins should be utilized.
In cases where excess amounts of nutrients, pesticides and animal wastes
cause particular problems in surface or ground waters, additional control
measures may be necessary. These measures might relate, for example,
to the application (timing and amount) of fertilizers and pesticides, the
prevention of the concentration of animals, and the collection and adequate
disposal of the animal wastes. Salinity buildup resulting from irrigation
must be analyzed in terms of the particular problem with subsequent develop-
ment of appropriate measures.
Description of Prevention and Reduction Measures
Measures which can be applied to an agricultural management unit
to prevent or reduce pollutants from reaching surface or ground waters
can be generally classified into four categories. They are: (1) structural
measures, (2) conservation cropping systems and animal management
systems, (3) quantitative and qualitative management of cropping system
inputs, (4) vegetative measures.
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Structural measures generally involve some physical method designed
to reduce erosion or prevent sediment runoff. They include such things
as barriers applied at the source such as terraces, conveyance systems
to enhance non-erodable flows such as waterways and drop structures,
and catchment systems for the final clarification such as debris basins.
Off-stream watering points, controlled access watering points at water
bodies, diversions around feeding areas, and manure trapping basins
are considered to be structural measures.
Cropping systems and animal management systems involve the spacial
and sequential arrangement of crop plant and animal pop-
ulations. The arrangement of crops on a field such as strip cropping,
crop rotation such as sod-forming grass rotation systems, and tillage
methods such as minimum tillage can significantly reduce pollutant trans-
port. Control of animal populations so as to prevent overgrazing or the
concentration of animals in particular locations 'can reduce erosion,
sediment runoff, and the runoff of concentrated animal wastes.
Inputs into cropping systems which are not efficiently utilized can
become potential pollutants. Nutrient and pesticide applications should
be matched to the immediate needs of the agricultural production
systems. The timing of the applications should take into consideration
external hydrologic forces. The efficient use of irrigation water can
materially reduce the salinity buildup problems associated with runoff,
seepage, and percolation of the water not utilized by the plants.
Vegetative covering on bare, or exposed soils is any crop planted
solely to prevent, or control erosion and sediment runoff. It can be
used during the winter months, between regular crops during the growing
season, or where denuded areas have resulted from overgrazing or
some other activity. The vegetative cover protects the bare ground
from the erosive energy of falling rain and flowing runoff water and filters
out sediment actually being transported in the runoff water leaving the site.
Information Sources
The prevention and reduction measures outlined in the foregoing are
generally described in "Methods and Practices for Controlling Water
Pollution from Agricultural Nonpoint Sources, " EPA-430/9-73-015. Oct 1973.
Data on control of dust is presented in "Investigation of Fugitive Dust,
Volume 1: Sources, Emissions, and Control" EPA-450/3-74-036a
June, 1974, Specific information on the application of the measures for
agricultural nonpoint sources and water quality management is contained in
"Control of Water PoUution from Cropland, Volume I " USDA, ARS
and EPA, ORD. November 1975. "interim Report on Loading Functions
For Assessment of Water Pollution from Nonpoint Sources" EPA; ORD.
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November, 1975 provides data for assessing the problem. Information
on specific aspects of agricultural nonpoint source pollutants and their
control can be found in research reports of EPA, USDA, and other Federal
agencies. State and local agencies, colleges and universities, and agricultural
trade associations and in grazing and range management documents by these
groups.
Design information on various conservation methods can be
obtained from Soil Conservation Service handbooks. Specific infor-
mation on particular locations can be obtained from SCS Field Offices,
the Extension Service, soil and water conservation district offices, and
other informed agencies and groups.
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