?/EPA
United States
Environmental Protection
Agency
Office of Water
Washington DC 20460
July 1987
Guide to
Nonppint Source
Pollution Control
ji f\n.i
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Controlling
Nonpoint Source
Pollution
a guide
U. S. Environmental Protection Agency
Criteria and Standards Division
Washington, DC
1987
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Prepared under contract 68-01-6986 for the U.S. Environmental Protection
Agency. Research and technical information by Battelle Columbus Divi-
sion; reviewed by Criteria and Standards Division, U.S. Environmental
Protection Agency. Manuscript and design by JT&A, Inc. Approval for
publication does not signify that the contents necessarily reflect the views
and policies of the Environmental Protection Agency, nor does mention
of trade names or commercial products constitute endorsement or recom-
mendation for use.
PHOTOGRAPHS: The Federal Highway Administration, the National Ag-
ricultural Library, and the Soil Conservation Service and Forest Service
of the U.S. Department of Agriculture.
COVER ART: David Stolar.
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Contents
Foreword v
Introduction 1
Evaluation of Modeling and Other Assessment Techniques . . 5
Nonpoint Source Pollution Models 9
Best Management Practices 33
Sources 111
Glossary 117
Index: Models and Best Management Practices 121
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Foreword
This document is designed as a user's guide to the techniques
now available for controlling nonpoint source pollution. The reader
will find first a general evaluation of nonpoint source modeling and
other techniques, followed by a chapter assessing models now
in use, and a third chapter summarizing best management prac-
tices.
Sources of information used are listed at the conclusion of the
text. In the third chapter, end notes are used to substantiate
studies referred to in the discussion of best management prac-
tices.
This is not, however, a literature search or a summary of re-
search; rather, it has been developed by intensive research and
distilled into a practical guide for the decisionmaker who must
choose from among many techniques for approaching nonpoint
source pollution control.
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Introduction
Under the Clean Water Act of 1972 this Nation
has steadily progressed toward attaining its na-
tional water quality goals—but now that we have
regulated the disposal of municipal and in-
dustrial waste, we find that our waters still suffer
from pollutants. It has been easy to understand
how waste flushed into a city's sewers—or dis-
charged directly by a manufacturer—pollutes
the water it enters. So, using the provisions of the
Clean Water Act, we have cleaned up the waste
that continuously pours from pipes.
Unfortunately, only half of our pollutants come
from pipes—the rest come from nonpoint sour-
ces: our land, our fields, our streets. One might
explain the difference between point and non-
point as "pipe" and "non-pipe," but the real dif-
ference lies in the word "continuous." Nonpoint
source pollution is extremely variable—because
nonpoint source pollution occurs only when it
rains.
Rain washes pollutants from our land into
our water. Moving water is the driving force;
however, the pollutants that enter the water
result directly from man's activities on the land,
and therefore, vary greatly both by time and
space. For example, manure deposited and
frozen on an open field during the winter proba-
bly won't release its nutrients into a nearby lake
until spring, when the thaw is followed by rain.
Understanding this relationship between
hydrology and the variability of the specific cir-
cumstances is the key to understanding non-
point source pollution. This relationship dispels
the mystery of nonpoint source pollution. While
it may not lend itself to traditional collection and
discharge control methods, nonpoint source pol-
lution can be analyzed statistically. And that
analysis can point the way to the solutions—
which can be as diverse as the problems.
Diverse, nonpoint point sources may be, but
complex they are not. They must be approached
on a logical basis, and they must be solved by
us all. Obviously, we cannot maneuver all the
nitrogen and phosphorus running off a 40-acre
(or even 1-acre) field into a sewage treatment
plant that removes these nutrients before they
enter the water. Absurd as that task may be, so is
placing the sole responsibility for water pollution
control on county and State employees hired to
do the job.
The water professional's first task is to edu-
cate his public. The terms "runoff" and "nonpoint
source pollution" must become as familiar to the
citizen as "sewers" and "pipes." Citizens must un-
derstand that runoff originates in their yards, on
their farms, and in their streets, and that when
they change some of the ways they do things,
they prevent this pollution. The widespread insis-
tence on nonphosphate detergents is an ex-
ample of public acceptance of such a challenge.
Backed by a knowledgeable public, State and
local governments can develop management
strategies to control nonpoint source pollution.
Although nonpoint sources vary by area, agricul-
tural pollutants are the most pervasive, with
urban sources next in importance. In addition,
runoff from highways and waste disposal sites,
failed septic systems, mining and logging activi-
ties, and construction sites all contribute to the
problem.
Pollutants carried by these nonpoint sources
can be grouped by source and effects:
• Sediments resulting from erosion (of both
cropland and streambanks), livestock ac-
tivities, and construction site runoff com-
prise the greatest volume by weight of
materials transported. Sediments—and the
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pollutants they carry—eventually affect
recreational, industrial, and municipal
water uses as well as aquatic habitats.
Sediments can also fill reservoirs, harbors,
and navigable waterways, often necessitat-
ing dredging.
Fertilizers, phosphorous and nitrogen, are
found in both point and nonpoint dischar-
ges, and are largely responsible for ac-
celerating the aging and decay (eutrophica-
tion) of lakes and streams. Often, large
quantities of organic matter such as
manure carry these nutrients into the
water. The nutrients in themselves are not
pollutants: their effects depend on the
chemical form of the material, the con-
centrations, and the physical properties of
the receiving water.
Pathogenic (disease-bearing) microorgan-
isms are introduced from agricultural sour-
ces such as livestock feedlots and from
leaky septic tank systems and leach bed
systems. Although urban stormwater runoff
also contributes measurable bacteria,
most bacteria originate from animals rather
than humans. These microorganisms may
encourage the spread of infectious dis-
eases, eventually creating a major public
health problem.
• Pesticides, herbicides, metals, and other
toxics, particularly from agriculture, silvicul-
ture, mining, and lawn and landscape care
not only threaten surface water, but are
also being found with increasing frequency
in ground water. Where the surface is per-
meable, the water percolates downward,
carrying materials in solution with it. Harm-
ful pollutants carried down into the soil can
become fixed to clay or soil particles, per-
haps eventually entering a groundwater
aquifer. Mining may expose toxic metals
that can then be mobilized, usually through
the high acidities associated with mine
drainage. In northern climates, trace con-
taminants in road salts also contribute to
the release of some metals. Since ground
water is used more and more for irrigation,
livestock, and human consumption, the ef-
fects of these toxic substances must be
controlled.
In the 15 years that have passed since the
Clean Water Act took the first concrete step
toward coping with the pollution of our Nation's
POLLUTANT PATHWAYS
RUNOFF (SURFACE WATER)
Figure 1.—
2
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waters, we have largely controlled point sour-
ces, and learned a great deal about nonpoint
sources.
Nonpoint source pollution affects far more
than the water clarity: studies demonstrate that
controlling nonpoint source pollution produces
economic benefits even beyond the obvious
relationship between apparent lake water
quality and its use by swimmers and boaters. For
example, farmers can reduce cultivation costs
by using conservation tillage; communities can
cut dredging costs and improve recreation by
controlling runoff to decrease siltation.
Now, we find we must also be aware of the ef-
fects of nonpoint source pollution on human
health—not swimmer's itch that one can avoid by
staying out of the lake, but disease that comes
almost invisibly through our drinking water that
is drawn from ground water. Ultimately, a team
must be formed to solve this problem: an in-
formed public backing alert State and local
professionals who are using the most effective
technical solutions to reduce nonpoint source
pollution of our surface and ground waters.
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Evaluation of Modeling
and Other Assessment
Techniques
Numerous mathematical models and other as-
sessment techniques have been developed to
help make reliable and cost-effective decisions
about nonpoint source control methods and
their costs, and to relate land use to pollutant
transport and effects on water bodies. This sec-
tion identifies criteria for selecting and evaluat-
ing these decisionmaking tools, and describes
the most useful categories for managing non-
point source pollution. Particularly emphasized
are those techniques that exhibit three key at-
tributes:
• Account for the role hydrology plays in in-
fluencing pollutant behavior.
• Address spatial and temporal variability in
pollutant generation, transport, and
delivery.
• Relate contaminant concentrations to best
mangement practices (BMPs).
The nonpoint source assessment techniques
either employ statistics or simulate the transport
• PHYSICAL MODELS
Nonpoint source models are divided into two
categories—physical and decision-oriented (see
Figure 2). Physical models address the causes
and effects in terms of physical variables of a
process. They use hydrologic characteristics to
estimate pollutant delivery to receiving waters
from land use in agricultural, silvicultural, con-
struction, and urban areas.
The information developed from these techni-
ques can be used to identify the environmental
effects of nonpoint source pollution. For ex-
ample, by applying a probabilistic analytical tech-
nique to determine the effect of urban water-
shed runoff on instream water quality, the mean
recurrence intervals for a specific pollutant's con-
centrations during storm events can be com-
puted from representative values for the stream
and runoff conditions. This information helps
identify how often pollutant concentrations occur
that could be a problem, for example, to the
aquatic organisms in receiving waters. Decision-
makers may use such information to evaluate the
effects of alternative urban runoff management
practices on water quality.
process, and generally estimate either water
quality characteristics or mass transport in non-
point source pollution. Physical models are
based on deterministic or stochastic simulation of
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relevant physical, chemical, and biological
processes. The methods can range from simple
techniques that estimate average annual pol-
lutant loadings to ones that predict detailed tem-
poral and spatial distribution of pollutants.
Physical models predict runoff and mass
transport. They may calculate annual sum-
maries or time-varying pollutant loadings, and
may estimate pollutant concentrations in various
environmental media. Physical models do not
necessarily address every parameter that af-
fects water quality. Users may modify and adapt
them on a case-by-case basis. Many physical
models also have been extended to link a non-
point source pollutant loading rate to different
receiving water bodies.
DECISION-ORIENTED MODELS
Decision-oriented models go beyond the physical
models to calculate cause and effect relation-
ships in terms of decision variables. They may
evaluate the effects of a control practice on water
quality and mass transport, and also may
analyze its environmental impacts based on dif-
ferent criteria for decisionmaking. A control prac-
tice such as urban runoff treatment can be
evaluated based on an analysis of its effects (for
example, protection of aquatic life).
In listing the attributes of both types of models,
Figure 2 shows that decision-oriented techniques
may go beyond physical models to also
• stress understanding of relationships be-
tween management activities and water
quality.
• focus on ecosystems and watersheds
rather than on individual environmental
components.
• permit the evaluation of options and trade-
offs of combinations of BMPs from both ef-
fects and cost standpoints.
Assessment tools such as the fish habitat
models (for example, COWFISH used by the
Forest Service) are decision-oriented. They are
designed to evaluate the effect of changes in
the riparian environment (such as might be
caused by sediment or grazing) on the aquatic
resources.
Another example of a decision-oriented tech-
nique is an agricultural nonpoint source model
that incorporates BMPs such as sedimentation
and erosion control systems, plant nutrient loss
control, and agricultural waste management.
Some of these models can predict a BMP's ef-
fects on the ecology and water quality of receiv-
ing water bodies. Other models may include an
economic analysis component that permits a
decisionmaker to compare capital investment
and operation and management costs for various
BMPs or combinations of them.
SELECTING THE RIGHT MODEL
The user's specific requirements determine how
any model is to be applied. It is important to un-
derstand that the two categories may be used
together. That is, one may employ a decision-
oriented technique to screen a number of dif-
ferent management practices based on a cost-
benefit analysis or an environmental impact
analysis. Subsequently, physical models can be
used to comprehensively analyze the selected
processes.
Figure 3 illustrates how to evaluate and sel-
ect a technique. In this approach, one must first
identify those environmental processes and
management techniques that may prevent or
mitigate the nonpoint source pollution problem.
The available models are then characterized as
shown in Figure 2. Next, it is important to estab-
lish whether the model is operational and has
been used successfully. Nonvalidated models
should be used only with extreme caution, if at
all, because of potential inaccuracies and unac-
ceptability of results.
Validated models should then be evaluated by
comparing the information desired with the
costs of using the model. Using a pollutant
runoff model is worthwhile if the value of the in-
formation obtained (ultimately expressed as im-
proved decisionmaking) exceeds the cost of its
use. Examples of such values include the
model's ability to simulate the parameters (pol-
lutant loadings, runoff, etc.) and the processes
(snowmelt, chemical adsorption, biodegrada-
tion, etc.) and to assess the effect of BMPs on
aquatic environment. An additional value would
be an improved data base for future use.
The costs include acquiring the model, collect-
ing data, modifying and calibrating the model,
and using it for various scenarios. These values
and costs should be carefully studied to deter-
mine whether a particular model can achieve
the expected goals within resources available.
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NONPOINT SOURCE POLLUTION ASSESSMENT TECHNIQUES
(AGRICULTURE, SILVICULTURE, URBAN RUNOFF, CONSTRUCTION)
STATISTICAL
SIMULATION
PHYSICAL MODELS
DECISION-ORIENTED
TECHNIQUES
ATTRIBUTES*:
• Predict mass transport and loading
• Calculate average annual or time varying
pollutant loads
• Estimate pollutant concentrations in various
environmental compartments
• May simulate chemical/physical/biological
processes
• May predict water quality changes in receiving
bodies
ATTRIBUTES:
• Include BMPs
• Link capital, operation and management cost
of BMPs to water quality benefits
• Permit risk/benefit analysis of different BMPs
on beneficial receiving water uses
• Address impacts on the environments
'These attributes also may be relevant to Decision-Oriented Techniques.
Figure 2. —
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TECHNIQUE CHARACTERIZATION (PHYSICAL VERSUS DECISION)
DEVELOPMENT OF INFORMATION FOR THE STUDY
Are the Study Objectives,
Information Development
and Scope of the
Technique Compatible?
YES
Has the Technique
Been Validated?
YES
VALUE
Model Parameters of Interest
•
Model Processes of Interest
•
Results/Output Options
•
Documentation and Availability
of User Assistance
•
Incorporates BMPs, Policy Choices*
NO
NO
1
Risk/Benefit
Analysis
1
Capital Investment
O&M Cost
Choose
Another
Technique
Validate After
Studying Values
and Cost
COST
Model Acquisition
•
Data Gathering/Generation
•
Model Calibration/Trial Runs
•
Model Execution for
Different Scenarios
Cost to Validate the Model
'For Decision Models
Figure 3. — Selection of NPS pollution assessment techniques.
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Nonppint Source
Pollution Models
The models discussed in this section esti-
mate one or more of the following parameters:
(1) runoff, (2) sediment concentrations, and (3)
nonpoint source pollutant loads. Although
Tables 1 and 2 list both physical and decision-
oriented models, only the latter are described
here because they focus on implementation.
These models are operational, having been
used successfully at least once.
A third category, receiving water models, is
listed in Table 3. Although they are not dev-
eloped specifically for nonpoint source pollu-
tion, these models can simulate effects on the
receiving water—an ability some of the physical
and decision-oriented models lack. Decision-
makers can use receiving water models to
select appropriate implementation models.
The decision-oriented techniques establish
relationships between BMPs and water quality,
approach ecosystems and watersheds as an in-
tegrated whole, and, in a few instances, permit
both a cost and benefit evaluation of BMPs.
Many of them are modifications of physical
models, which are process-oriented, simulating
hydrologic, transport, and other physical, chemi-
cal, and biological processes.
This assessment of decision-oriented techni-
ques is based on a number of different criteria.
Of course, the model should be operational and
validated by successful use. Techniques under
development or that need further refinement
should be assessed after the models are
validated.
The capability of the model to simulate the fol-
lowing parameters also needs to be considered:
• Meteorology (rainfall, temperature,
snowfall), hydrology (subsurface flow,
surface runoff, stream flow), and water
body (lakes, estuaries, oceans).
• Spatial (single catchment, multiple
catchments) and temporal (annual,
event-based, continuous) simulations.
• Land use (agricultural, silvicultural, con-
struction, urban).
• Policy choices, BMPs, and associated
costs of implementation.
• Environmental effects on beneficial use
of receiving waters.
• Ability to simulate on a field or land
management unit basis.
• Extent of input data requirement
(detailed, moderate, minimal), type of
data, and relative availability.
• Need to modify or calibrate model for
specific applications.
• User-friendliness of the model.
• Availability of user's manuals, reports,
and support to facilitate implementation
of the program.
• Hardware and software required.
• Costs associated with purchasing neces-
sary items, services, and implementa-
tion.
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Table 1.-NPS pollution assessment techniques/models: physical models.
TITLE
ACIMO
DR3M
EPA Screening Procedures
ILLUDAS
MUNP
PRMS
PRS
STORM
UTM-TOX
WLFNPS
OBJECTIVE
To simulate runoff and transport from agricultural lands
To simulate urban watershed runoff, sediment yield and water quality
To estimate nonpoint source loads
To estimate urban runoff using an event-based analysis
To estimate the accumulation of pollutants on urban streets
To evaluate the effects of precipitation, climate and land use or
general basin hydrology
To simulate runoff; and other hydrologic quantities
To estimate the runoff, sediment and pollutant delivery of
urban watersheds
To estimate the concentrations of pollutants and theirfate and transport
in the environment
To estimate runoff, sediment and pollutant concentrations in runoff in large
agricultural watersheds
Table 2.-NPS pollution assessment techniques/models: decision models.
TITLE
AGNPS
ARM
ANSWERS
CREAMS/CREAMS 2
COWFISH
ESRFPP (Feedlot model)
GAWS
GLEAMS
NFS
NURP
SWAM
SWMM:Levell
SWMM
WRENS
OBJECTIVE
To simulate sediment, nutrient and pollutant transport in an
agricultural watershed
To simulate runoff and other contributions in streams
To predict hydrologic and erosion response of agricultural watersheds
To simulate hydrologic quantities, erosion and chemical transport
To assess the effect of current and past livestock grazing on associated
aquatic resources
To evaluate and rate the pollution potential of feedlot operations
To assess the effect of sediment yields on stream habitat and fish
populations for planning purposes
To simulate pesticides and nutrients leaching from agricultural watersheds
To continuously simulate hydrologic processes
To evaluate the effect of urban location, management practices, etc.
on urban runoff and receiving water bodies
To evaluate the effects of different land use and management practices
on a small watershed
To estimate runoff and water quality in an urban watershed
To simulate runoff, sediment and nutrient transport in an urban watershed
To evaluate the alternative management decisions used in silviculture
10
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Table 3.-Receiving water models.
TITLE
CHNTRN
CTAP
DEM
EXAMS
FETRA
LAKECO
MEXAMS
MichRIV
Ms. CLEANER
QUAL-II
RECEIV-IT
SERATRA
SLSA
TOOAM
TOXIC
TOXIWASP
WASP/AESOP
WASTOX
OBJECTIVE
To simulate time varying distributions of sediments and chemicals
in receiving waters
To account for dissolved and steady-state concentrations of pollutants
in the water column and bed sediment
To simulate the unsteady tidal flow and dispersion characteristics
of an estuary
Rapid screening and evaluation of the behavior of synthetic organic
chemicals in freshwater ecosystems
To simulate the transport of sediments and contaminants in rivers
and estuaries
To evaluate the consequences of remedial measures for lakes
To estimate the quantities of metals likely to be in solution
To simulate the advective transport of dissolved and adsorbed pollutants
To evaluate nonlinear, nutrient-algae cycles, multi species
andphytoplankton
To simulate the dispersion and flow characteristics of stream systems
and rivers
To evaluate receiving water by representing physical properties
To predict distributions of sediments and toxic contaminants in rivers
To analyze chemicals in simplified lake and stream settings
To simulate sediment transport, dissolved contaminant transport,
and sorted contaminant transport
To simulate the behavior of pesticides in a reservoir and bkxoncentration
of pesticides in aquatic life
To simulate the transport and transformation of organic toxic chemicals
in the water column and the sediment of stratified lakes, reservoirs, rivers,
estuaries and coastal waters
To allow the specification of time-variable exchange coefficients,
advective flows, wastetoads, and water quality boundary conditions
To simulate the transport and transformation of organic chemicals in the
water column and the sediment of streams and estuaries
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Description
AGNPS is a single-event based model intended to simulate sediment and nutrient
transport from agricultural watersheds in Minnesota. It is also being used and
tested in neighboring States (principally Nebraska and Iowa), with the intention
of adding pesticide simulation. The model works on a cell basis, and the water-
shed (ranging from 2.5 to 23,000 acres) can be divided into 1-acre elements.
The model predicts runoff volume and peak rate, eroded and delivered sediment,
nutrient (nitrogen and phosphorous) concentration, and chemical oxygen demand
in the runoff, and the sediment for single storm events for all the cells in the water-
shed.
Capabilities
• Compares the effects of various BMPs.
• Analyzes pollutant loads from feedlots.
• Estimates water quality parameters at intermediate points throughout the
watershed network.
• Estimates erosion for five different particle sizes (clay, silt, small aggregates,
large aggregates, and sand).
• Subdivides transport portion into soluble pollutants and sediment-attached pol-
lutants.
Limitations
• Used only for single events.
• Has undergone only limited testing for pollutant transport.
• Not adequately tested for particle size distribution during transport.
• Does not simulate receiving waters.
Input Data
Classified into two categories: watershed data that includes information that ap-
plies to the entire watershed and to the storm event to be simulated, and cell
data that includes physical information and parameters based on the land conser-
vationpractice. Data required may be obtained through Minnesota Land Manage-
ment information Service (LL45 Metro Square, 7th and Robert, St. Paul, Min-
nesota 55101), visual analysis, maps, topographic and soils data, technical publi-
cations, or the AGNPS manual.
Output Description
The basic output from AGNPS includes hydrology; runoff; and sediment,
nutrient, and chemical oxygen demand. The output can be examined for a single
cell or for the entire watershed. Detailed sediment and nutrient analyses
(weighted and mean) are also available.
Availability
AGNPS is a fairly new model. The manual written by Robert A. Young and
others in 1986 provides a list of references for additional data and a number of in-
dividuals to contact for further information. The Guide to Model Users is in press.
For further information, contact Robert A. Young, Agricultural Research Service,
USDA, North Central Soil Conservation Research Lab, Morris, Minn. 56267;
phone 612/589-3411.
Resource Requirements
AGNPS is written in FORTRAN IV computer and developed on a Hewlett-Packard
1000 computer. A IBM-PC compatible version requiring 256K memory is available
for monochrome screen (version 1.0) or graphics (version 1.1).
Agricultural
Nonpoint
Source
Pollution
Model
AGNPS
13
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Aerial
Nonpoint
Source
Watershed
Environment
Response
Simulation
ANSWERS
Description
ANSWERS is an event-based surface hydrology model that estimates hydrologic
and erosion response of agricultural watersheds. The area to be studied must be
subdivided into a finite number of square grids, with parameter values specified
for each grid. The model simulates interception, infiltration, surface storage, sur-
face and subsurface flow, and sediment detachment, transport, and deposition.
Has been extensively validated in the Midwest.
Capabilities
• Can evaluate different erosion control management practices for agricultural
lands and construction sites.
• BMPs can be evaluated by modifying soil infiltration values and surface condi-
tions.
• Modular program structure permits modification of existing program code and
the addition of user-supplied algorithms.
• Grid analysis allows for consideration of spatial variation of hydrologic and sedi-
ment processes.
Limitations
• Simulates only single events.
• Pesticide fate/transport and snowmelt processes cannot be simulated.
• Watershed site is small.
• Does not process on a land management unit basis.
Input Data
Input information for the ANSWERS model contains simulation requirements,
rainfall information, soils data, land use and surface information, channel descrip-
tions, and individual element information that includes BMPs.
Output Description
The output listing consists of input data, watershed characteristics, flow and sedi-
ment information at the watershed outlet, effectiveness of structural BMPs, net
transported sediment yield or deposition for each element, and channel deposi-
tion.
Availability
Documentation and user support, including a User's Manual, are available free
from U.S. EPA Region V. The ANSWERS program was developed by D. B. Beas-
ley and L F. Muggins at Purdue University under EPA sponsorship. For further in-
formation, contact Professor Beasley, Department of Agricultural Engineering,
Purdue University, West Lafayette, Ind. 47907; phone 317/494-1198.
Resource Requirements
Written in Fortran, the program will run either on a PC or a mainframe. Requires a
large memory, especially to simulate large watersheds. The data files have been
designed to use Soil Conservation Service soil surveys, U.S. Geological Survey
topographic maps, and crop and management surveys.
14
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Description
The ARM model simulates the hydrologic, sediment production, pesticide, and
nutrient processes on the land surface and in the soil profile that determine the
quantity and quality of runoff in small agricultural watersheds. The major com-
ponents of the model individually simulate the hydrologic response of the water-
shed, sediment production, pesticide adsorption/desorption, pesticide degrada-
tion, and nutrient transformations.
Capabilities
• Can simulate surface runoff, subsurface flow, and snowmett.
• Both event-based and continuous simulations are available options.
• Includes different management practices.
Limitations
• Application is limited to agricultural watersheds less than 5 km2 (1.9 sq. miles).
• No channel routing procedures are included.
• Model does not link the cost associated with different BMPs to pollutant load-
ings.
Input Data
Detailed input data are required for simulating hydrology, snowmelt, sediment,
pesticides, and nutrients. Some data must be generated from physical water-
shed and pollutant characteristics, land surface conditions, agricultural cropping,
and management practices. Calibration and verification data are also required.
Output Description
The printout provides summaries of runoff, sediment, pesticides, and nutrient
loss in addition to nutrients remaining in the various soil zones. Generally, the out-
put summaries are printed daily or monthly, but can be obtained hourly.
Availability
The model was developed by Hydrocomp, Inc., Palo Alto, Calif., and is available
through Tom Bamwell at the Water Quality Modeling Center, Environmental
Research Laboratory, U.S. EPA, College Station Rd., Athens, Ga. 30613; phone
404/546-3175. The model is adequately documented.
Resource Requirements
The model has been tested on the IBM 370/168 using the FORTRAN H com-
piler. The program requires approximately 360K bytes of storage for compilation
of the largest subroutine, whereas program execution requires up to 230K bytes
of storage, depending on the model options selected. However, Version II of the
ARM model has been adapted to run on a Hewlett-Packard 3000 Series II com-
puter, which is substantially smaller than the IBM machines on which the model
was developed and tested.
Agricultural
Runoff
Management
Model
ARM
15
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Chemicals,
Runoff, and
Erosion from
Agricultural
Systems
CREAMS
Description
CREAMS and CREAMS 2 are field-scale models that simulate surface and sub-
surface runoff, evapotranspiration, erosion, sediment yield, and plant nutrient
and pesticide delivery. One purpose of these models is to evaluate BMPs. User-
defined management activities simulated by CREAMS 2 include aerial spraying or
soil incorporation of pesticides, animal waste management, and alternative
agricultural practices such as minimum tillage and terracing. USDA is modifying
CREAMS 2 to make the model more user friendly. The model does not need to be
specifically calibrated for a given watershed. Most of the required parameter
values are physically measurable.
Capabilities
• Represents soil processes with reasonable accuracy.
• Simulates continuously; considers event loads.
• Can simulate up to 20 pesticides at one time.
• Includes BMPs.
Limitations
• Subsurface drainage is not simulated.
• Data management/handling capabilities are limited.
• Maximum size of simulation area is limited to field plots.
• Receiving waters are not simulated.
Input Data
CREAMS and CREAMS 2 require extensive data on meteorology, hydrology,
erosion, and chemistry of the pollutants.
Output Description
Output can be very detailed. Erosion data are available for each element con-
sidered.
Availability
Program manuals, tapes, and floppy disks can be obtained from the USDA-ARS
Southeast Watershed Research Laboratory, P.O. Box 946, Tifton, Ga. 31793;
phone 912/386-3462.
Resource Requirements
The model can be run on mainframe computers (IBM) or on personal computers
(IBM-PC, AT&T).
16
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Description
The COWFISH model is designed to assist resource specialists analyze the con-
dition of the riparian environment in relation to past and current livestock grazing
management and to estimate the compatibility of grazing with associated aquatic
resources. It is not intended to replace presently used stream surveys or fish
population analyses. Rather, it uses existing information to derive an initial indica-
tion of how livestock grazing may be affecting trout populations.
The model considers six variables in determining a stream's suitability to support
trout: (1) the extent of the streambank which is undercut, (2) the extent of the
stream edge with vegetational overhang, (3) the extent of the streambank show-
ing bare soil or trampling, (4) stream embeddedness, (5) stream width, and (6)
stream depth. Two additional variables, stream gradient and the drainage soil
type, are used to calculate fish production and recreational and economic value.
The field value obtained for each variable is converted to a parameter suitability
index (PSI) based on principles similar to those developed by the U.S. Fish and
Wildlife Service in its habitat suitability index models. The PSI values are then
averaged to compare the stream's existing habitat conditions with its potential
habitat suitability index.
Capabilities
• Although originally developed for the mountainous regions of central Montana,
after some adjustments this model can be used throughout the western United
States.
• Can be used to determine stream habitat productivity any time during the
season prior to snow cover.
• Can accurately assess current habitat conditions, provided the sampling area is
at least 100 feet long.
• Can be used to evaluate larger sections of uniform streams. Data from five sites
per stream mile would be needed to provide a 10 percent sampling of the
study area.
• Can analyze a wide variety of riparian and stream types (the variation being in
dimensions, flow conditions, streambank conditions, and surrounding environ-
ment).
Limitations
• Accuracy diminishes when the estimated analysis of grazing effects on fish
production does not immediately follow the modeled livestock use.
• Less accurate for use along streams with rocky streambanks that do not follow
the natural development of undercut banks.
• When sample areas smaller than 100 feet are used, the results will reflect
population numbers only for the immediate area.
Input Data
Requires field data that include descriptive information about the stream, allot-
ment, and sample size being evaluated. Specifically, information is needed on
sample size, vegetative type, side valley slope gradient, percentage of undercut
banks and banks supporting vegetative overhang, embeddedness, streambank
alteration, width/depth ratio, and stream gradient.
Cows
and
Fish
COWFISH
17
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Cows and
Fish
COWFISH
Output Description
The printout is in tabular form and contains information on the optimum number of
catchabie trout per 300 m of stream for {1) optional conditions for this stream and
(2) existing conditions. The losses from optional conditions are also displayed,
that is, the number of trout per 300 m of stream per year, recreation loss in
wildlife and fish user days, and economic loss in dollars per 300 m of stream per
year.
Availability
The model was developed by the U.S. Forest Service's Northern Region Wildlife
and Fish Habitat Relationships Program. Copies are available from USDA Forest
Services, Federal BkJg., P.O. Box 7669, Missoula, Mont. 59807; phone 406/329-
3101.
Resource Requirements
The user may obtain the results either manually by following the Guide to the
Field Form or through a computer by recording the variables in the field and
using the Data General software program developed for this model. The manual
procedure provides the flexibility of obtaining the results while still on the site.
No programing knowledge is required.
18
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Description
The animal lot evaluation system, developed to evaluate and rate the pollution
potential of feedlot operations, consists of two parts: (1) a simple screening proce-
dure that evaluates the potential pollution hazard associated with the feedlot,
and (2) a more detailed analysis that is better able to identify feedkrts that are not
potential pollution hazards. The Soil Conservation Service's curve number
method is used to estimate the runoff. Chemical oxygen demand and phos-
phorous are the two parameters used as the pollutant indicators. The ESRFPP
model has been tested in several States. Currently, the Minnesota Pollution Con-
trol Agency requires that all animal lots in the State be rated by employing this
model.
Capabilities
• Estimates pollutant discharge using simple techniques.
• Can be used as a screening procedure.
• Considers both surface and groundwater pollution potential.
• Evaluates the effects of different land management practices.
Limitations
• Runoff calculations may not be valid for large tributary areas (more than 100
acres).
• Model does not deal with receiving water bodies.
• The discharge point defined in the model may be difficult to apply in the field.
• Potential pollution threats to ground water are treated lightly.
Input Data
Data requirement is minimal. Most of the required data are presented in the
ESRFPP manual.
Output Description
The model estimates the concentration of pollutant indicators at the discharge
point.
Availability
The method is well documented in the ESRFPP manual. Further assistance is
available from Robert A. Young, North Central Soil Conservation Research Lab,
Agricultural Research Service, USDA, Morris, Minn. 56267; phone 612/589-3411.
Resource Requirements
All the calculations can be performed using a small desktop calculator. Programs
have been developed to use with Hewlett-Packard 67/97/41C, Monroe 325, and
Compucorp 327 calculators.
Evaluation
System
To Rate
Feedlot
Pollution
Potential
ESRFPP
19
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Groundwater
Leaching
Effects on
Agricultural
Management
Systems
GLEAMS
Description
GLEAMS is an extension of USDA's CREAMS models. GLEAMS simulates
leaching of pesticides and nutrients from agricultural watersheds. The leaching
behavior of pesticides in root zones has been tested and validated. The model is
being modified to incorporate subsurface nutrient transport and the effects of
variability in soil porosity at different depths. The GLEAMS model is in develop-
ment/testing stage. For more information, contact Walter G. Knisel, Jr., USDA-
ARS, Southeast Watershed Research Laboratory, P. O. Box 946, Tifton, Ga.
31793; phone 912/386-3462.
20
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Description
Sometimes referred to as GAWS, this guide is not a computer program. It
provides a standard method for predicting the effect of sediment on stream habitat
and fish populations for planning purposes. GAWS estimates sediment yields
resulting from past activities such as fire, road construction, and logging. On-site
erosion is modified according to general characteristics and delivered to a
stream channel where it is routed to a critical stream reach—a segment of the
stream that biologists select to predict changes in fish habitat, fish embryo sur-
vival, summer rearing capacity, and winter carrying capacity. Model outputs are
reasonable estimates that are intended to be used with sound biological judg-
ment. The model will help land managers quantify existing and potential impacts
and evaluate trade-offs to fish resources from forest management.
Capabilities
• Can determine sediment yields.
• Can predict habitat changes resulting from sediment yields.
• Can predict fish population changes caused by habitat changes.
Limitations
• Average sediment deposition in high gradient streams may not realistically rep-
resent deposition in fish habitat.
• The efficiency of high gradient channels for sediment transport may lead to
sediment concentration in downstream channels with lower gradient.
• Increased sediment production from land types drained by high gradient chan-
nels may have a greater impact downstream than analysis of only high
gradient channel drainage would indicate.
• The laboratory-determined response of salmonid fish populations to increased
sediment levels that the model uses may not approximate the response in the
field.
• The model was developed and tested only for salmonid species associated
with the Idaho Batholith. Application in other systems would require testing.
Input Data
The following types of data are needed to operate this model: (1) estimates of
sediment yield, (2) substrate core samples to determine existing conditions and
natural conditions, (3) measurements of substrate embeddedness in critical
reaches, (4) stratification of stream by channel type, and (5) sufficient informa-
tion on the fish populations.
The following additional types of data would assist in interpreting the results: (1)
substrate coring data from several surrounding streams over time, (2) substrate
embeddedness for most of the fish production areas, (3) redd count or adult es-
capement data, (4) fish density/standing crop data, (5) classification of the
stream by geomorphic and channel type, (6) stock-recruitment data over time,
(7) empirical relationships between sediment yields and fish habitat, and (8) a
calibrated watershed model.
Output Description
No special output as such. The step-by-step procedure described in the manual
can be used to calculate changes in the fish populations.
Guide for
Predicting
Salmonid
Response
to Sediment
Yields in
Idaho
Batholith
Watersheds
GAWS
21
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Guide for
Predicting
Salmonid
Response
to Sediment
Yields in
Idaho
Batholith
Watersheds
GAM'S
Availability
This guide was developed by and may be obtained from the U.S. Forest Service's
Northern Region and Intermountain Region, Federal BkJg., P.O. Box 7669, Mis-
soula, Mont. 59807; phone 406/329-3101.
Resource Requirements
Since a computer is not required for using this guide, minimal resources are
needed.
22
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Description
The HSPF is a series of fully integrated computer codes that simulate watershed
hydrology and the behavior of conventional and organic pollutants in surface
runoff and receiving waters. The processes that affect the fate and transport of
pesticides and nutrients from agricultural land are derived from the Agricultural
Runoff Management (ARM) model, whereas the sediment delivery algorithms
are from the Nonpoint Source (NFS) model. The HSPF contains three application
modules: the PERLND (pervious land) and IMPLND (impervious land) modules
perform the land and soil simulation for those land surfaces; the RCHRES
(reach/reservoir) module simulates the processes that occur in a single reach and
the bed sediments of a receiving water body (a stream or well-mixed reservoir).
Extensive and flexible data management and statistical routines are available for
analyzing simulated or observed time series data.
Capabilities
• Consists of systematic modular framework that allows a variety of operating
modes, including continuous hydrdogic simulation.
• Nonpoint source loading (including alternative control practices) and receiving
water quality simulation are integrated into a single package.
• HSPF can analyze relative contributions and impacts of both point and non-
point source loadings; offers options to use either simplified or detailed repre-
sentations of nonpoint source runoff processes.
• Models risk assessment of the exposure of aquatic organisms to toxic chemi-
cals delivered to receiving waters.
• By adjusting parameters, can include different agricultural management prac-
tices.
Limitations
• Calibration is usually needed for site-specific applications.
• A long time period (2-3 months) may be required to learn the operational details
of applying HSPF if the user has no prior experience.
• Model does not link the cost associated with different BMPs to pollutant
delivery.
• Depending on the extent of model use, computer costs for model operation
and data storage can be a significant fraction (10-15 percent) of total applica-
tion costs.
Input Data
ff all modules are selected for model implementation, the HSPF requires an ex-
tensive amount of data. The meteorological and some hydrologic data are time
series inputs.
Output Description
The HSPF output includes system state variables, temporal variation of pollutant
concentrations at a given spatial distribution, and annual summaries describing
pollutant duration and flux. A summary of time-varying contaminant concentra-
tions is provided along with the link between simulated receiving water pollutant
concentration and risk assessment.
Availability
HSPF is in the public domain and can be obtained from the Center for Water
Quality Modeling, Environmental Research Laboratory, U.S. EPA, College Station
Road, Athens, Ga. 30613; phone 404/546-3175. The EPA Water Quality Model-
ing Center provides user assistance on an ongoing basis, periodically scheduling
free training sessions.
Hydrological
Simulation
Program —
Fortran
HSPF
23
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Hydrological
Simulation
Program-
Fortran
HSPF
Resource Requirements
HSPF requires a FORTRAN compiler that supports direct access I/O. Twelve ex-
ternal files are required. The system requires 128K bytes of instruction and data
storage on virtual memory machines or about 250K bytes with extensive overlay-
ing on overlay-type machines. It has been installed on several systems, including
IBM, DEC, VAX, System 10/20, Data General, MV4000, CDC Cyber, HP3000,
HP1000, and Burroughs and Harris.
24
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Description
The NPS model continuously simulates hydrologic processes, including snow ac-
cumulation and melt, and pollutant accumulation, generation, and washoff from
the land surface. Sediment and other suspended material are used as basic in-
dicators of nonpoint pollutants. Simulates erosion on both pervious and imper-
vious areas.
Capabilities
• Can simulate urban, agricultural, and silvicultural nonpoint source pollution.
• Both event-based and continuous simulations are available options.
• Can simulate nonpoint pollution from a maximum of five different land use prac-
tices in a single simulation run.
• Different agricultural and construction management practices can be simulated.
Limitations
• Does not consider subsurface flow, groundwater pollution, or channel proces-
ses.
• Simulates only sediment and nutrient transport processes; does not estimate
pesticide delivery.
• Does not simulate the relationship between cost of BMPs and runoff as pol-
lutant loadings.
Input Data
Requires extensive input data, including those related to model operation,
parameter evaluation, and calibration.
Output Description
The output from the NPS model includes (1) output heading (summary of the
watershed characteristics, simulation run characteristics, and input data), (2)
time interval output (can be for 15-minute intervals) and storm summaries, (3)
monthly and yearly summaries, and (4) output to interface with other models (op-
tional).
Availability
This model, developed by A. S. Donigian and N. H. Crawford of Hydrocomp, Inc.,
Mountain View, Calif., under U.S. EPA sponsorship, is available through EPA's
Water Quality Modeling Center, Environmental Research Laboratory, College
Station Rd., Athens, Ga. 30613; phone 404/546-3175. The model is well docu-
mented and has been tested for the simulation of nutrient loadings in surface
runoff.
Resource Requirements
The NPS model was developed on IBM 360/67 and 370/168 computers. Later,
it was adopted to UNIVAC 1108, CDC 6000, and Honeywell Series 32. The com-
puter core requirements for compilation and execution can be as high as 194K
and 144K bytes, respectively. With a reasonable level of technical support, it is
expected that 2 to 3 man-months will be required to use and apply the NPS
model.
Nonpoint
Source
Loading
Model
A/PS
25
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Nationwide
Urban
Runoff
Program
NURP
Technique Description
The NURP is not a computer model: rather, it may be considered to be a statisti-
cal-based technique that addresses the effects of urban locations, management
practices, etc., on urban runoff and receiving waters.
EPA used the NURP to build on prior work on urban stormwater pollution and to
provide practical information and insights to guide policy and planning. The NURP
program included 28 projects, all of which were involved in one or more of the fol-
lowing activities:
• Characterizing pollutant types and their effects on receiving water quality.
• Determining the need for controlling stormwater pollution.
• Evaluating alternatives for controlling stormwater pollution.
Capabilities
• Includes methodologies and information on unban runoff characteristics and
controls, stormwater management, data analysis, results interpretation, and
receiving water quality effects of urban runoff.
• Facilitates decisionmaking by using qualitative statements, quantitative es-
timates, and graphic llustrations.
Availability
A large number of reports (about 77) resulted from this program. The program
report, Results of the Nationwide Urban Runoff Program, Complete Set,
published by EPA in 1984, consists of the executive summary, final report, appen-
dices, and data appendix. Other reports include case studies. The reports are
available from the National Technical Information Service, U. S. Department of
Commerce, 5285 Port Royal Road, Springfield, Virginia 22161; phone 703/487-
4650. For additional information, write to the EPA Headquarters Nonpoint Sour-
ces Branch, WH-585,401 M St. SW, Washington, DC 20460. A floppy disk con-
taining the program also is available from that office.
26
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U.S. EPA's SWMM package has several versions whose use depends on the
level of effort available and the amount of information required to estimate runoff
and water quality in an urban watershed. These versions include:
• SWMM—Level I
• Simplified SWMM
• SWMM
Description
SWMM—Level I is designed as a screening tool to provide a rough estimate of
quantity and quality during a precipitation event that lasts a few hours in an
urban watershed. The calculations can be performed with a hand calculator.
Runoff and water quality parameters are determined on the basis of land use
characteristics, precipitation, population density, sewerage system, and street
sweeping operations. A graphic procedure permits the analyst to examine a wide
variety of control options operating either parallel or in series with one another.
Capabilities
• No computer expenses.
• Includes economic analysis of sewerage management practices.
Limitations
• Relatively crude model.
• Does not consider the water quality changes in storage.
Input Data
Does not need a great deal of input data.
Output Description
Minimal output: the calculations are performed with a hand calculator.
Availability
The technical manual for this preliminary screening procedure is available from
EPA. Write to the Nonpoint Source Branch, WH-585, 401 M St. SW,
Washington, DC 20460.
Resource Requirements
Requires few resources because the data need is minimal and computers are
not used.
Stormwater
Managemen
Model
SWMM
Level I
27
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Stormwater
Management
Model
SWMM
Simplified
Description
The simplified SWMM simulates runoff and nutrient transport in an urban water-
shed. The five tasks performed in this model include data preparation, rainfall
characterization, storage-treatment balance, overflow-quality assessment, and
receiving water response. Each task generally combines small computer
programs with hand calculations.
Capabilities
• Can be linked to simplified, single-event receiving water model.
• Available options include continuous and event-based simulations.
• Models effect of pollutant delivery on receiving waters.
Limitations
• Does not consider water quality change or treatment during storage.
• Does not simulate snowmelt and sediment transport.
• Overflow quantities and qualities must be measured to calibrate model.
Input Data
Input data include hourly precipitation, runoff coefficient, treatment rate, storage
volume, and receiving water characteristics.
Output Description
Output contains time-varying overflows and runoff and summation of these data.
Pollutant loadings and receiving water response also are included.
Availability
The various SWMM models are available from EPA's Nonpoint Source Branch,
401 M St. SW, Washington, DC 20460. However, incomplete documentation and
inadequate user support are problems with using the model.
Resource Requirements
The computer programs for simplified SWMM have been developed on an IBM
360/67 digital computer. The storage-treatment program has been used success-
fully on Xerox 560 and IBM 1130 computers.
28
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Description
SWMM is a comprehensive, mathematical model capable of representing urban
stormwater runoff and combined sewer overflow phenomena. Level surface runoff
generated by precipitation is routed through channels and pipe networks. The
analysis uses finite difference approaches. The water quality parameters simu-
lated in SWMM include sediment and nutrients.
SWMM contains its own receiving water model, RECEIV. It also can be linked to
STORM, QUAL-II, and other simplified receiving water models.
Capabilities
• Both combined and separate sewerage systems may be evaluated.
• Considers treatment in five different storage systems.
• Includes several physical and chemical treatment options to evaluate water
quality changes.
• Includes capital and operating and management costs for treatment options.
• Can simulate the effects of pollutant delivery on the quality of receiving waters.
• Different storage and treatment techniques may be considered as options for
controlling nonpoint source pollution.
Limitations
• Is a large model with complex and detailed input requirements.
• Statistical summaries are limited.
• Uses a monthly flow routing method that can be costly because it requires short
time steps.
• It is comprehensive, but data management capabilities are not advanced.
Input Data
Detailed input data sets are required. Some of the input information typically re-
quired includes precipitation, air temperature, wind speed, channel, pipe net-
works, land use patterns, and storage and treatment facilities.
Output Description
Output consists of summaries of treatment options and costs, variation of water
quality with time, and hydrographs and pollutographs with daily and hourly varia-
tions.
Availability
The model is well documented and available from EPA in four versions: Final
Report, Verification and Testing, User's Manual, and Program Listing. The exist-
ence of established user groups that meet semiannually is considered an impor-
tant factor that promotes its use. For a copy, write to EPA's Nonpoint Source
Branch, 401 M St. SW, Washington, DC 20460.
Resource Requirements
The computer hardware system should be the equivalent of the IBM 360/65 with
peripheral storage devices and a usable core capacity of no less than 360K bytes.
Data requirements are common to engineering design and analysis, and are
mainly descriptive of the real system.
Stormwater
Management
Model
SWMM
29
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Small
Watershed
Model
SWAM
Description
SWAM is a continuous simulation model that estimates change in hydrologic,
sediment, and chemical characteristics of a small agricultural watershed in
response to different land use and management practices. The overland flow
and pollutant transport are estimated by CREAMS 2. The movement and interac-
tions of sediments, pesticides, and nutrients in the surface drainage (channel net-
work), and surface retention basins (reservoirs) are simulated. The model also
can simulate surface/groundwater interactions.
Capabilities
• Is an integrated watershed model that uses a dynamic version of CREAMS 2
together with channel, reservoir, and groundwater routing of water, sediment,
nutrients, and pesticides.
• Incorporates backwater effects in channel routing.
• Provides a detailed representation of soil and watershed processes.
Limitations
• A complex model to use.
• Watershed area is less than 10 km2.
• Not practical for long-term (20 years or more) simulations.
Input Data
Input data include rainfall, soil characteristics, topography, land use, and manage-
ment practices.
Output Description
The model developers are still working on output structure.
Availability
Model is still being tested and has not been released yet. Intended as a re-
search model that can later be upgraded to basin scale. The model will be avail-
able from Dr. Donald DeCoursey, USDA-ARS, P.O. Box E, Fort Collins, Colo.
80522;phone 303/221-0578.
Resource Requirements
Initially written in FORTRAN for mainframe computers.
30
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Description
WRENS is a procedural handbook for evaluating the effects of forest-related ac-
tivities on water quality and making management decisions.
WRENS describes procedures that can be used for quantitatively estimating
changes in the stream flow, surface erosion, soil movement, sediment discharge,
and temperature. In addition, WRENS includes qualitative assessment of
forestry activities on pesticide concentration, nutrients, organic matter, and dis-
solved oxygen. WRENS also lists criteria for selecting appropriate control
measures to minimize adverse effects of forestry activities on water resources.
Runoff volumes necessary for water quality analyses can be estimated from
precipitation and daily minimum-maximum air temperature data. One procedure
(WATBAL) is used to calculate runoff calculation in areas where snowmelt is the
major source of energy. The other procedure (PROSPER) is used for nonhuman
areas. WRENS uses the modified soil loss equation (MSLE) to calculate sediment
erosion in forests.
Capabilities
• No computer required.
• WRENS handbook is self-contained and includes examples.
• Handbook identifies BMPs.
Limitations
• Designed only for small site-specific areas.
• Nutrients, pesticides, dissolved oxygen, and organic mater are evaluated only
qualitatively.
Input Data
Input information includes watershed hydrology and daily meteorological data.
Output Description
No special output as such. Procedures described in the handbook can be used
to estimate some physical and chemical characteristics.
Availability
Handbook available from the National Technical Information Service, U.S.
Department of Commerce, 5825 Port Royal Rd., Springfield, Va. 22161; phone
703/487-4650. Specify No. EPA 600/8-80-012. Cost: $58.95.
Resource Requirements
Resource requirements for this analysis are minimal.
Water
Resources
Evaluation
of Nonpoint
Silvicultural
Sources
WRENS
31
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Suggestions to Improve Models
Models can be important tools for assessing
nonpoint source pollution as well as projecting
the effects of BMPs. However, most of the exist-
ing decision-oriented models have distinct limita-
tions and require further refinement. The follow-
ing improvements could be most useful:
• Develop the ability to simulate proces-
ses in grids or cells so that one com-
puter run could evaluate different BMPs
for different spatial distributions of a
given watershed.
• Improve the capability for analyzing the
cost/benefit relationship.
• Improve the ability to simulate environ-
mental impact and risk analysis: for ex-
ample, pesticide levels toxic to various
organisms in receiving waters, eutrophi-
cation of receiving water bodies by
nutrient loadings, and effects of bio-
chemical oxygen demand on dissolved
oxygen level in streams and consequent
strain on aquatic organisms.
• Develop the ability to evaluate total im-
pact resulting from redispersion of the
bottom sediments and sorbed or settled
pesticides and nutrients.
• Improve the models' capabilities for han-
dling data and results for statistical
analyses and interpretations.
• Incorporate graphic illustrations in the
outputs.
• Simulate nonpoint source pollution of
ground water from subsurface runoff.
This problem, that is, separation of inter-
flow from surface hydrograph, is not ade-
quately addressed in most of the exist-
ing models. More fundamental work
should be done on hydrograph separa-
tion.
32
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Best Management
Practices
Since nonpoint source pollution can be at-
tributed to various land disturbances, specific
methods have been developed to minimize both
these disturbances and the runoff they generate.
These methods are known as BMPs, for .best
management practices.
Synonymous with prevention, BMPs use the
land in fhe wisest possible ways—whether it be
for growing crops or grazing cattle, building high-
ways or cutting trees. BMPs are exactly what
the phrase implies: coordinated, judicious timing
of activities and use of vegetation and materials
(including some structures), as components
within a total land management system.
Rarely viewed as remedies to past problems,
BMPs function as ingredients in a so-called
"prescription" to control a specific nonpoint
source effect. Perhaps the best example of this
approach can be seen in farming, where a
management scenario might combine half a
dozen practices and structures—from contour
terraces and no-till planting to buffer strips and
dikes. Each specific practice would be selected
and applied according to the overall use of the
land.
Applications for best management practices
overlap: fertilizer and pest management techni-
ques, for example, can be applied to both agricul-
ture and forestry. BMPs also vary with specific
application, with standard practices taking on dif-
ferent forms when used, for example, in a mining
situation as opposed to highway construction.
In an attempt to describe the most commonly-
used BMPs, this Guide classifies them into
broad categories defined by land use:
• agriculture
• construction/urban runoff
• silviculture
• mining
A last classification—multicategory—includes
BMPs that are used in all the others.
Agriculture: Agricultural BMPs are particular-
ly well-known (and numerous) because agricul-
ture is regarded as the primary source of pollution
to rivers and lakes, contributing at least half of the
sediment deposited in streams and lakes. The
American Water Works Association has named
agricultural runoff as the largest contributor of
nitrogen and phosphorus to water.
More detailed information about agricultural
BMPs is available from the National Water
Quality Evaluation Project (NWQEP), a USDA-
EPA cooperative venture to determine the most
effective ways for controlling agricultural non-
point source pollution at the watershed level.
NWQEP's 1985 Annual Report describes 20
projects that studied watershed controls inten-
sively. The report is available from North
Carolina State University at Raleigh.
Mining: Commercially-mined and processed
minerals range from fuels such as coal and oil to
metals to nonmetallic minerals like sand and
gravel, stone, phosphate, and clays. Mining
operations include deep mining, strip mining,
auger mining, open pit mining, placer mining and
dredging, well extraction, solution mining, and
other types.
In addition to the extraction of minerals, mini-
ng involves transport, exploration, processing,
storage, and waste disposal. Each phase has
its own activities—and its own potential for pollut-
ing water, either during operation or following
shutdown.
Specific preventive measures must be
designed for each operation on the basis of an
examination of the site and the consequences
33
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expected from its use for mining. EPA has
developed a list of 17 general control principles
that should be applied to selecting and
designed BMPs for mining:
1. Choose least hazardous methods.
2. Manage water.
3. Control erosion and trap sediment.
4. Segregate water from toxics.
5. Collect and treat runoff when other ap-
proaches fail.
6. Quickly stabilize disturbed area.
7. Properly store minerals and dispose of
mineral wastes.
8. Correct pollution-causing hydrologic distur-
bances.
9. Prevent and control pollution from roads.
10. Avoid disturbing streambeds, stream-
banks, and natural drainageways.
11. Use stringent controls in high risk areas.
12. Apply sound engineering.
13. Properly locate and seal shafts and bore-
holes.
14. Control fugitive dust.
15. Maintain control measures.
16. Use temporary stabilization and control
when needed.
17. Prevent and control pollution after close-
down.
The mining section describes several specific
BMPs used in mining that are based on the
cited control principles.
The matrix in Table 4 relates the individual
BMPs in all categories to one another, and to
the total management plan.
By combining Table 4 with the text, which in-
cludes cost information for each BMP, the reader
will have the tools to weigh alternative solutions
to specific nonpoint source pollution problems.
Table 4. — Best management practice activity matrix.
AGRICULTURE
Conservation tillage
Contouring
Contour strip cropping
Cover crops
Integrated pest management
Range and pasture management
Sod-based rotations
Terraces
Waste management practices
CONSTRUCTION & URBAN RUNOFF
Structural control practices
Nonvegetative soil stablization
Porous pavements
Runoff detention/retention
Street cleaning
Surface roughening
SILVICULTURE
Limiting disturbed areas
Log removal techniques
Ground cover
Removal of debris
Proper handling of haul roads
MINING
Water diversion
Underdrains
Block-cut or haul-back
MULTICATEGORY
Buffer Strips
Grassed waterway
Devices to encourage infiltration
Interception/diversion
Material ground cover
Sediment traps
Vegetative stabilization/mulching
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
34
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Agriculture
-------
Conservation tillage refers to any planting sys-
tem that reduces soil disturbance and water loss
by retaining crop residues on the land (covering at
least 30 percent) and leaving the surface rough,
porous, cloddy, or ridged. Identified under sev-
eral different names—minimum tillage, reduced
tillage, stubble mulching—conservation tillage in-
cludes no-till, ridge-till, strip-till, mulch-till, and
reduced-till. Conservation tillage reduces runoff
and directly benefits farmers, but may require
special equipment and additional costs.
Experience and Application
The conservation tillage system that best fits a
farm operation depends on the climate, soil
characteristics, and the crops grown. While
lower yields have been experienced on some
soils, research has generally found no sig-
nificant yield differences between conventional
and conservation tillage practices.1 Conservation
tillage also reduces labor, time, fuel usage, and
machinery wear. The preferred conservation til-
lage method depends on the soil. Although ap-
plicable to a wide range of soils, reduced til-
lage is considered more suitable to cold and
wet soils than no-till, with soil drainage largely
determining its economic success. Reduced til-
lage maintains productivity because it reduces
erosion and soil compaction and conserves
moisture, improving soil structure and optimiz-
ing land resources. Reduced tillage is more
widely adaptable than no-till planting but is
somewhat less effective in controlling water pol-
lution. No-tillage is most applicable on highly
erodible, well-drained, coarse to medium-tex-
tured soils planted in dormant grass or small
grain crops. Farm use of conservation tillage is
increasing rapidly, from about 27 million acres in
1972 to 74 million acres in 1979, and 99.6 mil-
V'^'V...;,
-. \yv:5^
Conservation
Tillage
agriculture
37
-------
Conservation
Tillage
agriculture
lion acres in 1985. The Conservation Tillage
Information Center in 1986 estimated a 2.8 mil-
lion-acre increase in conservation tillage prac-
tices from 1984 to 1985. The Center also com-
pared 1984 and 1985 according to conservation
tillage type: no-till increased by 700,000 acres;
ridge-till by 45 percent; strip-till declined by
50,000 acres; and mulch-till, accounting for 64
percent of all conservation tillage, grew by 6.7
million acres'3
Capital and Operating Costs
An important reason for the increasing use of
conservation tillage is the decreased overall
capital expense and increased net return. One
study found the average diesel fuel consump-
tion for reduced-till was 1.4 gallons/acre and 1.0
gallon/acre for no-till, compared to 4.2 gal-
lons/acre for conventional tilling.4 An analysis of
crop production costs indicated that reduced til-
lage decreased equipment and labor costs by
• Effectiveness
All conservation tillage practices reduce erosion
potential below that of conventional tillage, in
some estimates by 30 percent, with runoff declin-
ing by about 61 percent. Leaving crop residue
in the field protects the soil surface from the
erosive forces of rain water and snowmelt by
preventing surface sealing, which increases in-
filtration and decreases the volume and velocity
of runoff. Conservation tillage is particularly ef-
fective in controlling sediment loss and phos-
phorus and pesticide transport, although
declines in transport vary with the type of soil
and reductions in sediment. On-site effective-
ness of preventing these pollutants from enter-
ing surface waters ranges from 40 to 90 percent
reduction for conservation tillage to 50 to 95 per-
cent reduction for no-tillage.7 In South Dakota,
researchers found that as much as 7.5 cm rain-
fall produced no surface runoff with conservation
tillage, while only 2.0 cm rainfall produced run-
about 8 percent and no-tillage by about 10 per-
cent.5 Another researcher concluded that in-
creased material costs for conservation tillage
practices were more than offset by reduced
costs for machinery and items.6 To encourage
conservation tillage, Virginia and North and
South Carolina offer farmers a state income tax
credit of 25 percent (to a maximum $2,500 per
year) for purchasing no-till farm equipment.
off with conventional tillage.8 Another study
found that surface runoff averaged 1 mm per
season for no-till plots and 11 mm per season on
conventionally tilled plots.9 Conservation tillage
may increase groundwater contamination if it
relies more on more pesticide usage than con-
ventional tillage. Research has shown,
however, that conservation tillage does
necessarily require more pesticide
The Integrated Pest Management BMP discus-
ses this issue in more detail.
not
usage.10
38
-------
Contouring
agriculture
Plowing follows the contours of the field (perpen-
dicular to the slope of the land). Crops are then
planted along these tilled contours.
Experience and Application
Especially applicable on cropland with 2 to 8 per-
cent slope, contouring provides more protection
from erosion than tilling parallel to the slope.
Contouring is limited by soil, climate, and topog-
raphy, and may not be usable with large farming
equipment under some topographic conditions.
Capital and Operating Costs
Contouring costs are slight because it does not
require any specialized farming equipment, nor
does it affect fertilizer and pesticide application
rates. However, a proper plowing design must
be established.
39
-------
Contouring
agriculture
• Effectiveness
Contour plowing can reduce average soil loss
(and therefore phosphorus and pesticide runoff)
by 50 percent on moderate slopes, less on
steep slopes. Contouring loses its effectiveness
if the rows break down, so for long slopes ter-
races may be needed. The contours provide ex-
cellent erosion control during moderate rains-
torms, collecting water and thereby reducing
runoff velocity and increasing the infiltration
time. However, contouring loses its effective-
ness during extreme storms when rainfall ex-
ceeds the surface storage capacity. When prac-
ticed alone on gentle slopes, or in combination
with strip cropping or terracing on moderate
slopes, contouring reduces erosion.
40
-------
Strip-
cropping
agriculture
Stripcropping alternates plowed strips of row
crops and close- grown crops such as pasture,
hay, or grasses to reduce erosion on tilled soils.
Strips of close-growing crops are planted between
tilled row crops to serve as sediment filters or
buffer strips in controlling erosion. The system of
cropping where the strips are laid out nearly per-
pendicular to the direction of the slope is referred
to as contour Stripcropping.
Experience and Application
Stripcropping is particularly applicable on
cropland with 8 to 15 percent slope, its primary
advantage being that it permits row crops on
slopes. Contour Stripcropping is nearly twice as
effective in controlling erosion as seeding grain
in the fall to replace pasture. However, for con-
tour Stripcropping, the farming area must be
suited for across-slope farming and for using
pasture as part of a crop rotation. Alternating
corn with spring grain is not effective for
Stripcropping.
41
-------
Strip-
cropping
agriculture
Capital and Operating Costs
Costs are slight because contour stripcropping
does not require the purchase of specialized
farming equipment, nor does it affect fertilizer
and pesticide application rates. However, a
farmer must have a use for both crops, and may
• Effectiveness
The practice reduces the velocity of the water
as it leaves the tilled areas, because the buffer
strip absorbs runoff and retains soil particles,
thus minimizing nutrient and pesticide entry into
suffer some production loss because of the al-
ternating system of planting. On some
topographies, contouring may not be compati-
ble with the use of large farming equipment.
surface water bodies. Planting row crop and
hay in alternate 50- to 100-foot strips reduces
soil loss by about 50 percent compared to the
same rotation contoured only.
42
-------
Cover crops are grown when the ground is nor-
mally bare, to protect the soil from leaching and
erosion. Grasses and other crops offer better
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 with small quantities of residue.
Experience and Applications
The cover crop technique is applicable to all
cropland. In appropriate climates winter cover
crops provide a good base for slot-planting the
next crop. For example, winter rye can be
seeded immediately after a corn crop is har-
vested for silage. The growing rye protects the
soil during the fall, winter, and early spring when
the field would otherwise be bare and subject to
erosion. Many cover crops are left on the soil
as a protective mulch or are plowed under to im-
prove the soil. Cover crops also may reduce
input costs and increase soil productivity. Heavy
soil cover, such as chopped corn or sorghum
stalks or straw, usually provides as much soil
protection as winter cover crops.
Capital and Operating Costs
The cost of using cover crops is moderate. No
special equipment is needed to incorporate
winter cover crops into a farming operation;
however, planting the cover crop will involve ad-
ditional man hours, machine use and main-
tenance, fuel, and seed. Research also has sug-
gested that water use by winter cover may
reduce the following year's cash crop yield.11
Cover
Crops
agriculture
43
-------
Cover
Crops
agriculture
• Effectiveness
Cover crops reduce soil and water loss, thus
minimizing loss of nutrients (and pesticides, if
present). Winter cover crops reduce erosion
where corn stubble has been removed and low-
residue crops harvested. They may reduce
leaching of nitrate. If the cover crop is chemical-
ly killed and left in place for no- till planting of a
row crop, it provides excellent control during the
crucial erosion period. One study reported that a
winter cover crop significantly reduced both soil
and water loss for no- till corn harvested for
silage, compared to growing the corn without
using winter cover.12 In general, cover crops
provide better protection from the erosive ef-
fects of precipitation than continuous intertilling
of crops. Cover crops reduce pollutant transport
to adjacent surface water bodies by 40 to 60 per-
cent.
44
-------
Fertilizers are used to increase the productivity of
the land. However, the very act of adding them to
the land increases the potential amount of pol-
lutants that can be carried away by rainfall. Judi-
cious use of fertilizers is therefore advisable to
achieve both increased productivity and minimal
effect on water.
Experience and Application
If the quantity and composition of fertilizers ap-
plied are based on crop needs and soil fertility,
plants will use the nutrients, thereby reducing the
amount of nutrients lost in runoff. Fertilizers also
may increase root density, which will make the
soil more permeable. On the other hand, if too
much fertilizer is used a nutrient imbalance may
result; followed closely by heavy rainfall, the
potential for polluting water bodies may be
great. Fertilizer transport to water varies with
crop absorption rates, rainfall, slope, soil type,
the closeness to a waterway, and the fertilizer's
propensity for movement by water or sediment.
When more than an inch of rainfall occurs within
a week of application, the delivery rate may in-
crease substantially. The consensus reached at
an EPA workshop in June 1986 was that to mini-
mize groundwater pollution, both fertilizers and
pesticides must be better managed. The follow-
ing summary is based on the conclusions of
EPA's Great Lakes National Program Office
Special Workshop:
Conservation tillage does not differ radically from
conventional tillage, and therefore, fertilizer
management is similar. The types of chemicals
may differ, but not the total quantity used: for ex-
ample, nitrogen fertilizer rates are similar with both.
However, nitrogen leaching is a problem for all til-
lage systems, although potentially greater for no-
till. Good fertilizer management can include
• optimizing crop planting time
• optimizing fertilizerformulation
• optimizing time of day for application
• optimizing date of application
• using lower application rates
Capital and Operating Cost
Improved fertilizer management is extremely
cost effective; in fact, the NWQEP 1985 Annual
Report found this to be the most cost-effective
BMP for reducing nutrient losses in most of the
• Effectiveness
Fertilizer (and pesticide) management is em-
phasized in all Rural Clean Water Program
(RCWP) projects as part of an EPA-USDA effort
to limit contamination of ground water. Using
studies described. Wise management of fer-
tilizer application can actually reduce the capital
invested in fertilizer, and may reduce the man-
hours and equipment and fuel cost of applying it.
conservation tillage without appropriate fer-
tilizer/pesticide management is not considered
an acceptable BMP.
Fertilizer
Management
agriculture
45
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Integrated pest management combines tradition-
al pest control methods (such as crop rotation
and pesticides) with sophisticated measures
such as trapping insects and analyzing their life
cycles to determine how best to destroy them,
and monitoring pests to improve the efficiency of
pesticides and other controls. Pesticides are ap-
plied at a minimal rate, the method and timing
carefully selected according to the targeted pest,
and using pesticides with the least persistence
and volatility.
Experience and Application
To reduce environmental impacts, agricultural
pesticides have changed in recent years, with
EPA also mandating application requirements to
minimize problems. The newer pesticides are
less persistent in the environment and, therefore,
have fewer long- term impacts, but they are also
more likely to be water soluble. This means that
water (instead of sediment) may carry them to
the water bodies. Because their water-soluble
forms may be more biologically available when
freely waterborne than sediment-bound forms,
these toxic chemicals may cause serious short-
term surface water problems and eventually
degrade groundwater resources.
Pesticide transport to water bodies varies
with crop adsorption rates, rainfall, slope, soil
type, the proximity of the land to a waterway, and
the pesticide's propensity for movement by water
or sediment. Normally, only about 5 percent of
total pesticides applied enter water bodies;
however, when more than an inch of rainfall oc-
curs within a week of pesticide application, the
delivery rate increases substantially and fish may
be killed. With this in mind, it is obvious that pes-
ticides must be managed better for all types of til-
lage, including more care with application rates,
timing, and methods.
Conservation tillage may increase ground-
water contamination. The consensus reached
at an EPA workshop on this subject in June 1986
was that to minimize groundwater pollution, pes-
ticides and fertilizers must be better managed
for all types of tillage. The following summary is
based on the conclusions of the EPA's Great
Lakes National Program Office Special Work-
shop.
Conservation tillage does not differ radically from con-
ventional tillage, and, therefore, pesticide/fertilizer
management is similar. The types of pesticides may
Integrated
Pest
Management
agriculture
47
-------
Integrated
Pest
Management
agriculture
differ, but not the total quantity used: for ex-
ample, nitrogen fertilizer rates are similar with
both. However, nitrogen leaching is a problem
for all tillage systems, but is potentially greater
for no-till. Farmers may use more insecticides
and herbicides as they begin to practice conser-
vation tillage, but often decrease these inputs
as they become more experienced with the sys-
tem.
Farmers can help control pesticide losses in a
number of ways, including
• combining mechanical cultivation with dis-
ease-resistant crop varieties,
• trying other pesticides,
• optimizing pesticide placement with
respect to loss,
• rotating crops,
• using resistant crop varieties,
• optimizing crop planting time,
• optimizing pesticide formulation,
• using mechanical control methods,
• reducing excessive treatment, and
• optimizing time of day for pesticide applica-
tion.
Other practices that have limited applicability
include optimizing date of pesticide application,
• using integrated control programs,
• using biological control methods,
• using lower pesticide application rates,
• managing aerial applications, and
• planting between rows in minimum tillage.
Capital and Operating Costs
The costs of an integrated pest management
program can vary widely according to practices
chosen. However, pesticide management is
• Effectiveness
An effective integrated pesticide management
program can reduce pollutant loadings by 20 to
40 percent, depending on the practices used.
A 1983 Report to the Great Lakes Water
Quality Board claims a 50 to 90 percent reduc-
tion in pollutant loading, as well as a direct im-
pact on instream water quality. Pesticide and
highly cost-effective and maximizes profits and
input costs.
14
fertilizer management is being emphasized in
all Rural Clean Water Program (RCWP)
projects, as part of an EPA/USDA effort to limit
contamination of ground water. Using conserva-
tion tillage without appropriate pesticide/fer-
tilizer management is not considered an accept-
able BMP.
48
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Rangeland and pastureland can be managed to
reduce erosion. Lands used for grazing vary in
climate, topography, soils, and vegetative type
and condition, a diversity that creates the poten-
tial for varying degrees of erosion. Erosion from
grazing land can be prevented and controlled by
minimizing the intensity of livestock use, and/or
increasing the productivity of the vegetation.
Grazing management practices should restrict
livestock use to the carrying capacity of the land,
thus minimizing erosion.
• Experience and Application
Overgrazing changes the soil structure because
the soil compacts, therefore becoming less per-
meable. Overgrazing also can change the den-
sity, vigor, and species composition of vegeta-
tion, thus exposing the soil to the erosive forces
of wind and water.
An adequate grazing regime should use
recommended stocking rates, discourage
animal congregation in critical areas, break up
animal distribution, and incorporate or remove
manure accumulations. Following are some
practices recommended for rangeland and pas-
tureland management:
• Rotation grazing permits intensive use of
fields or portions of fields on an alternating
basis. The nonuse period allows vegeta-
tion to recover before the livestock return.
• Water supply dispersal distributes the live-
stock better, thus reducing overuse or over-
grazing near water supplies, and sub-
sequent erosion hazards.
• Ponds in pastures conserve water while
providing water for livestock.
Seasonal grazing that is compatible with
the specific vegetation's most productive
period permits recovery and reseeding.
The dispersal and occasional relocation of
salt, mineral, and feed supplement sites
avoids concentrated overuse of these
areas.
Range
and
Pasture
Management
agriculture
49
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Range
and
Pasture
Management
agriculture
Capital and Operating Costs
Most of these management practices involve ap-
plying common sense and thoughtful manage-
ment to range and pasture use; they should not
require significant investments by farmers or
• Effectiveness
Restricting animal access to highly erodible
areas such as bare slopes will reduce erosion
ranchers. However, to use the various practices
most effectively, a farmer or rancher must know
such factors as stocking rates and vegetation
types and conditions.
and improve surface water quality.
50
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Sod-based crop rotation involves planting a
planned sequence of crops in regular succession
on the same land, rather than cultivating one
crop continuously. Sod-forming grasses and
legumes are used, with hay a part of the cycle.
Meadowless rotation (using crops that do not form
sod) employed by farmers to restore fertility to
their soils is far less successful than sod-based
rotation in combatting erosion. However, mead-
owless rotations do help control disease and
pests and may provide more continuous soil
protection than one-crop systems.
Experience and Application
Sod-based rotations1 may be used on all
cropland, particularly those farm operations with
livestock that can eat the hay grown as part of
the cycle. This system has been used for many
years to reduce erosion from the conventional
plow-based systems in regions adapted to rotat-
ing pasture for one or more years. Soil and
water loss from a good quality grass and
legume meadow is negligible, and plowing the
sod improves infiltration and reduces erosion.
Sod is most frequently used in two- to four-year
rotations. Legumes in the meadow mixture can
help restore the soil's nitrogen balance through
fixation of atmospheric nitrogen. Sod- based
rotations help control some diseases and pests
and also give the farmer more fertilizer place-
ment options. Along with increased labor re-
quirements, some climatic restrictions are as-
sociated with sod-based rotation farming.
Capital and Operating Costs
Sod-based rotations can be costly since the
farm's income is reduced by substituting hay for
as feed. Other than that, no additional equip-
ment or accessories need be purchased;
Sod-
Based
Crop
Rotation
agriculture
51
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Sod-
Based
Crop
Rotation
agriculture
major crops for one year during the rotation
cycle. This is less of a problem where livestock
are part of the operation, since hay can be used
• Effectiveness
Sod-forming grasses and legume crops used in
rotation with row crops are highly effective in
maintaining the soil structure and tilth. In addi-
tion, this type of rotation cycle can reduce soil
and nutrient losses by 20 to 50 percent. The
rotation of crops often provides for planting both
shallow- and deep-rooted plants; this pattern im-
proves the physical condition and the internal
drainage of both the soil and the subsoil.
however, labor hours may increase and cash
sales decline.
Hay fields lose virtually no soil and reduce
erosion from succeeding crops. Total soil loss
is greatly reduced; however, losses are unequal-
ly distributed over the rotation cycle. The poten-
tial for transport of water-soluble phosphorus in-
creases. Sod-based rotations improve weed
and insect control, thus reducing pesticide ap-
plications and the possibility of groundwater con-
tamination.
52
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A terrace is a ridge or embankment constructed
across a slope to control erosion. Terraces
reduce the slope and divert or store surface
runoff instead of permitting it to flow uninter-
rupted down the slope. Terraces break the
length of the slope into shorter segments, reduc-
ing the slope effect on erosion rates by dividing
the field into segments with lesser or even near-
horizontal slopes. The excess water either is
conveyed from the terraces to grassed outlets or
removed by subsurface drains. Some terraces
on permeable soils are designed to stop runoff
and hold the water until it is absorbed.
Terracing
agriculture
Experience and Applications
Terracing is generally applied to fields where
contouring, strip- cropping, and tillage opera-
tions do not protect the soil adequately. Par-
ticularly applicable on land with up to 12 percent
slope, terraces fill a niche in cropland conserva-
tion systems that no other practice can by con-
trolling sheet, rill, and gully erosion on steeper,
longer slopes. In 1977, terraces were used on
53
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Terracing 31.3 million acres in the United States.15 Ter-
race design requires detailed knowledge of prob-
able rainfall totals and intensity, soil characteris-
agriculture tics, and cropping systems. Terraces often re-
quire new management practices to maintain
their desired effects. They should be planned to
permit farming with large, modern equipment. If
terraces are improperly designed or used with
poor cultural and management practices, they
may increase rather than reduce soil losses.
Terracing can facilitate more intense cropping
and reduce downstream flood peaks.
Capital and Operating Costs
Terraces involve substantial initial cost, along
with some periodic maintenance costs;
however, in the long term, income usually in-
creases. Conventional gradient terraces have
been incompatible with use of large equipment,
but new designs have alleviated this problem.
Terraces can be constructed with a moldboard
or disk plow, whirlwind terracer, bulldozer,
motor grader, scraper, or similar equipment.
Many computer programs are available to
select the best terracing design.
• Effectiveness
By shortening long sloping areas, terracing
slows runoff and prevents the formation of gul-
lies, reduces soil loss, and conserves soil mois-
ture. Terraces have proven to be more effective
in reducing erosion than in reducing total runoff
volume per se. Farmers report better water
management, higher yields, and fewer wet
spots on terraced fields. One study reported
that a terrace with a vegetative outlet traps 60 to
80 percent of the sediment moving into the ter-
race channel.16 A terrace with a closed outlet
traps 92 to 98 percent of the sediment moving
into the channel. The Conestoga Rural Clean
Water Project in Lancaster County, Pennsyl-
vania, is trying to assess the impact of terraces
on groundwater quality by monitoring ground
water before and after terraces are built. The
monitoring has not yet continued long enough for
any conclusions to be made.
54
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Waste storage structures temporarily store animal
waste until they can be safely used. Although
usually constructed of reinforced concrete or
coated steel, earthen berms may also be used to
build ponds that can handle liquid and solid
animal wastes and runoff containing various pol-
lutants. However, earthen waste storage ponds
may leak, thus increasing the potential for
groundwater pollution. Diversions and dikes can
be used to direct contaminated runoff into the
storage pond or to route uncontaminated runoff
away from a confined animal facility. Waste
storage ponds must be designed to handle ex-
pected precipitation and runoff as well as the es-
timated volume of waste.
Experience and Application
Animal waste management practices must be
designed to meet the site conditions, type of
animal wastes, and farm management prac-
tices. In addition to storage facilities for animal
waste, runoff diversion structures are often
needed in barnyard areas to reduce waste
transport. Given the variability of site topog-
raphy and layout of barns, each farm requires
an individually-designed waste management
system. Proper design factors also must incor-
porate estimates of land application frequency
and duration. If convenient to operate, these sys-
tems can directly control the animal waste as
well as concentrate the manpower work load.
Piling or spreading animal wastes on frozen
ground (commonly done in northern states) or
during periods of high rainfall can increase
nutrient and organic loadings to water bodies. An
interesting example of the effectiveness of
manure storage has been demonstrated in an
EPA Clean Lakes project on the Cobbossee
watershed near August, Maine. Applying
manure to the fields during the winter months
was identified as the major source of pollution to
the lakes in the watershed. A cost-sharing
program with USDA along with some pressure
applied by the Cobbossee Watershed District
convinced most of the farmers in the watershed
Waste
Management
agriculture
55
-------
Waste
Management
agriculture
to construct manure hold facilities: in 1980, some
30 separate agricultural waste management
facilities were built at a total estimated cost of
$662,000. These facilities store manure for ap-
proximaley 80 percent of the animal units in the
watersheds of the three lakes. Ongoing monitor-
ing of water quality in the watershed's lakes is
proving the effectiveness of this management
system. Lake Parker, located in northeastern
Vermont, suffered from weeds, algae, and bac-
teria growths over the past decade. The Vermont
Department of Water Resources determined
that the lake's problems were caused by exces-
sive phosphorus and bacteria loads from 8 of
the 11 dairy farms located in the watershed. The
Soil Conservation Service, of the town of
Glover, and other sponsors joined together to im-
plement a Resource Conservation and Develop-
ment Project. All eight farms participated in the
pollution control project, which included proper
use and disposal of wastes through manure
storage, barnyard runoff control, and milkhouse
waste management. The project began in
January 1981 and ended in June 1982. The Lake
Parker Association claims that the project has
been highly successful; however, like the Cob-
bossee watershed, a longer period of evaluation
will be needed to establish trends in the lake's
response.
Capital and Operating Costs
Waste management practices are generally
costly, requiring farmers to make significant per-
sonal investments in agricultural pollution con-
trol (see Table 5). In considering the high cost of
building a waste storage structure, farmers must
be assured that manure storage systems not
only control pollution but benefit farm manage-
• Effectiveness
Effective containment of animal waste can
reduce phosphorus runoff by as much as 50 to
70 percent, thereby minimizing water quality im-
pacts and consverving fertilizer for food produc-
ment and farm productivity. Often the motivation
for implementing these practices is not better
water quality but convenience to the farmer.
Runoff controls are the cheapest waste manage-
ment practice to implement and have been found
to be very cost effective.
tion during the summer months. Waste storage
structures have advantages over less expensive
waste storage ponds such as less potential for
groundwater pollution and fewer odor problems.
Table 5. — Typical manure storage facilities and costs.
MANURE SYSTEM
TYPE FARM COMPONENTS
*TOTAL
COST
Dairy
90 milkers
20youngstock
freestall
Dairy
28 milkers
20youngstock
stanchion
Dairy Replacement
20 animals
stanchion
Poultry Litter
Stacking Site
20,000 Broilers
50'x 80'x 10'
Concrete storage
with push off ramps
and roof
Equipment
40' x 40'
Asphalt Pad with
8' Concrete headwall
and earth sides
Equipment
37' x 37' x 4'
Concrete storage
Asphalted barnyard
Runoff controls:
holding basin
450' diversion
40' x 40 '
Concrete Pad
with earth berms
39,578
3,080
14,168
4,774
$61,600
1,848
9,856
2,772
6,776
$21,252
7,469
3,234
693
2,310
$13,706
4,466
4,774
$ 9,240
* Costs have been updated to 1985 dollars Source US EPA, 1980C
56
-------
Urban and
Construction
-------
Structural controls are used when vegetation
alone will not provide the desired degree of
protection, or when flow concentrates in a
specific area, as it does in drainage courses.
Structural measures include drop spillways, box
inlet spillways, chute spillways, pipe drop inlets,
sod flumes, debris basins, and other grade con-
trols. These structures supplement sound conser-
vation measures, trap sediment, and reduce the
grade in water courses, the velocity of flowing
water, and peak water flows. Common structural
controls for construction sites include filters (prin-
cipally the gravel inlet and the filter berm), traps,
basins, and diversion structures. Diversion struc-
tures, basins, and similar practices also are used
in other urban environments.
Experience and Application
Standard designs may be available for sedi-
ment control structures such as inlet filters and
other small structures. Structures should be
built to provide maximum site protection. On
urban construction sites and major highway
projects where storm drains are used, preventing
sediment damage to the drainage system be-
comes especially important. Failure to trap
much of the sediment before it reaches an inlet
may result in costly damage to the storm
drainage system. It is also important to routinely
remove sediment from settling ponds and sedi-
ment basins, and to dispose of it in a manner
that will preclude its return to downstream areas
during storms. Usually a sediment pond is
cleaned out when it has reached 50 percent of
its sediment storage capacity.
In drainageways, bank protection and grade
stabilization structures help control channel
erosion. Bank protection structures involve either
Structural
Controls
urban and
construction
59
-------
Structural
Controls
urban and
construction
protective riprap placed directly on the bank or
in-channel structures that deflect or dissipate
the velocity of the flow impinging on the bank.
Grade stabilization structures consist of a series
of check dams (energy dissipators) that both dis-
sipate the energy of the flowing water and physi-
cally restrict downcutting of the channel.
Capital and Operating Costs
Costs vary widely according to the complexity of
the structure and its maintenance requirements.
Some sediment control structures such as
sandbag and straw bale sediment barriers may
require daily inspection because they are sub-
ject to vandalism. Diversion dikes, filter berms,
flexible downdrains, interceptordikes, level
• Effectiveness
Based on the present state of the art, it is dif-
ficult to assign an accurate universal effective-
ness value to a sediment control practice or com-
bination of practices. Many complex factors in-
fluence effectiveness, including soil erodibility,
climate, types of control practices being used,
physical characteristics of the sediment, and flow
characteristics. Also, adequate standard design
spreaders, sediment retention basins or ponds,
and other structures require inspection after
each rainstorm. Actually, the best time to inspect
most structural controls is during a major storm.
Corrective decisions made on-site at that time
can reduce sediment damages and operating
costs in the long run.
and construction criteria are not available for
many sediment control practices for different
slope conditions. Techniques are available,
however, for determining trapping efficiency in
large reservoirs. Sediment basins are generally
designed to have a minimum of 70 percent effec-
tiveness.
60
-------
Nonvegetative soil stabilization can be either tem-
porary or permanent. Temporary stabilization
uses covers and binders to shield the soil sur-
face from rainfall and runoff or to bind the soil par-
ticles into a more resistant mass. Permanent non-
vegetative soil stabilization usually consists of a
protective blanket of coarse crushed stone,
gravel, or other durable materials. On very steep
slopes, more rigid materials are required, such
as concrete, wooden or metal retaining struc-
tures, or concrete or asphalt pavements.
Experience and Application
Temporary stabilization protects the land during
grading and construction, while permanent
vegetation is developing or until another BMP is
completed. Nonvegetative stabilization can be
used anywhere erosive gradients exist, par-
ticularly at gully headlands. Various chemical
emulsions recommended for erosion control in-
clude polyvinyl acetate, vinyl acrylic copolymer,
and copolymer emulsions of methacrylates and
acrylates. Hydrated lime and cement can be
used for stabilizing clayey soils. Other tem-
porary stabilizers include mulches, nettings, and
textile blankets and mats.
Permanent stabilization becomes necessary
where vegetation cannot be used, such as ex-
cessively steep slopes, graded areas with
groundwater seepage, draughty or toxic soil,
and soil surfaces in waterways exposed to high
velocity concentrated flow.
Where both bank and channel erosion are
problems, complete channel linings can be
used; however, they should incorporate a
means for dissipating flow energy to prevent
serious erosion at the downstream terminus.
Various materials used for grade stabilization
in waterways include stone (used both as riprap
or in wire gabion baskets), concrete (used as
riprap, interlocking blocks, paving, or in con-
crete filled mattresses), and wood.
Although effective, this technique does not ad-
dress the cause of the suspended solids
problem, has no effect on soluble pollutants and
requires technical assistance.
Nonvegetativi
Soil
Stabilization
urban and
construction
61
-------
Nonvegetative
Soil
Stabilization
urban and
construction
• Capital and Operating Costs
The cost of nonvegetative soil stabilization can
vary greatly because there are many available
techniques.
• Effectiveness
Straw mulch (small grain) has proven effective
on 12 percent slopes at application rates of 5
ton/ha and on a 15 percent slopes at an applica-
tion rate of 10 ton/ha. On-site nonvegetative soil
stabilization reduces erosion by 75 to 90per-
cent.17 Straw mulching loses its effectiveness
on steep slopes because of rill formation and its
tendency to be washed away by overland flow.
-.- '•'. ."-j»v
^*S&-^ ***•" • «.
-------
Most porous pavements are made from asphalt
in which the fine filling particles are missing. The
porous asphalt mixture is installed on a gravel
base. If the pavements are designed properly,
most of the runoff can be stored and allowed to in-
filtrate into the ground. Where permeability of un-
derlying natural soil is not adequate or porous
pavement is installed over an impervious base, a
drainage system can be installed. If the drains
are not installed, the subgrade may soften.
Experience and Application
First used in Philadelphia, porous pavements
have been used in a number of States as well
as Denmark and Germany. Porous pavements
can be installed over existing impervious pave-
ments, an advantage in cities with combined
sewers (because it reduces the frequency of
overflow) or in areas with inadequate storm
drainage. The primary benefit of porous pave-
ments is that they significantly reduce runoff from
otherwise impervious areas. Other benefits in-
clude dissipation of runoff energy and associated
suspended sediment loss, infiltration of soluble
pollutants and some fine materials, and elimina-
tion of most hydraulic collection systems. Care
should be taken to prevent porous pavements
from polluting ground water.
r^lb*3S&P^ '.;
„**•%*
i*"\Si£n ."-
**"'* ' * CfiA^Cvuii
f 18r *
Porous
Pavements
urban and
construction
63
-------
Porous
Pavements
urban and
construction
Capital and Operating Costs
Porous pavements may sometimes cost slightly
more than conventional surfaces for parking
lots, roads, and other urban surfaces; however,
their benefits and savings on sewer and
drainage capacities, as well as on treatment, will
offset any the additional cost of the pavement.
• Effectiveness
Pollution loading by surface runoff from a
porous pavement should be zero if all water in-
filtrates. However, this may not happen, espe-
cially if the porous pavement is installed on an
impervious surface. In this case, the porous
pavement and the base act as a filter. Even
Dust and dirt that accumulate on top of the pave-
ment must be periodically removed or clogging
may occur. Therefore, porous pavements rely
on proper maintenance to achieve maximum
benefit.
when the ground is impervious, the porous base
and pavement are beneficial. The gravel base
serves as a storage area, and if the storm water
requires treatment, it may be stored in the
porous media until treatment capacity becomes
available.
64
-------
Runoff
Detention/
Retention
urban and
construction
Runoff storage facilities can prevent or reduce
storm water runoff, keeping associated pollutants
from entering combined sewers and surface
water bodies, and, if properly designed, ground
water. Detention facilities treat or filter out pol-
lutants, or hold the water for treatment prior to
release. A retention facility controls surge flows
such as runoff from storm events, but provides
no treatment. The water in a retention facility
either evaporates or infiltrates into the ground.
Experience and Application
Many variations of runoff storage facilities are
used on construction sites and in different types
of urban settings. A storage basin or a sewer's
storage can be used to contain storm discharge
or combined sewer overflow before releasing it
gradually—either after treatment into receiving
waters, or after a storm into a centralized treat-
ment facility. Storage facilities used for this pur-
pose can be either in-line or off- line and include
ponds or surface basins, underground tunnels,
excess sewer storage, and underwater flexible
(collapsible) holding tanks. A relatively new ap-
proach used in northern Europe and now being
considered by several U.S. cities, is the use of
floating detention basins in lakes or harbors to
hold runoff for treatment.
Retention facilities can be important sources
of groundwater recharge in highly impervious
urban areas; however, groundwater pollution
from these facilities must be considered.
Detention facilities can reduce the peak
runoff flow volumes from storms to trap sedi-
ment. Detention basins can be either dry (con-
ventional storm water management basins) or
wet (designs that maintain a permanent water
pool). Dry basins are designed to attenuate
peak runoff rates and, therefore, only briefly
detain portions of flow from larger storms. Over-
all, detention basins can very effectively remove
some pollutants in urban runoff; however, the
design and the size of the basin in relation to
the urban area served have a critical influence
on this capability.
Retention basins are increasingly being incor-
porated in highway designs to contain runoff.
One variation is to construct and contour high-
way interchanges so that open grassed areas
can be used as runoff storage. However, as with
all simple retention systems, this design can ad-
versely affect ground water. Water quality can be
protected by designing runoff control structures
to prevent infiltration of pollutants into ground
water, and to provide for settling, filtration, or
more substantial treatment prior to discharge to
surface water or ground water.
Runoff storage devices include small check
dams and earthen berms that increase the
storage capacity in existing streams and wet-
land areas; natural or excavated depressions
that store stormwater flows and slowly dis-
charge into the drainage system; grassed water-
ways (swales) that moderately improve urban
runoff quality; roof tops and parking lots
designed to serve as short-term detention
facilities in highly developed areas; and
depressed local recreational areas used for tem-
porary storage of runoff from adjacent areas.
Designs and general specifications for reten-
tion basins can be found in a manual developed
by the Nationwide Urban Runoff Program
(NURP): Retention/Detention and Infiltration
Devices for the Control of Urban Runoff. For a
copy, write to EPA's Nonpoint Source Branch,
401 M St. SW, Washington, DC 20460.
65
-------
Runoff
Detention/
Retention
urban and
construction
Capital and Operating Costs
Capital and operating costs largely depend
upon the type and size of the runoff storage
facility. Check dams and earthen berms may be
built inexpensively, but more expensive storage
systems (concrete vault storage structure) may
require significant excavation and construction.
According to NURP, on-site wet ponds serving
relatively small urban areas range from $500 to
$1,500 per acre of urban area served; approxi-
• Effectiveness
Storage and gradual release of storm water les-
sens the downstream impacts caused by flood-
ing, stream bank erosion, resuspension of bot-
tom deposits, and disruption of aquatic habitats.
Detention basins designed to control a peak
flow rate from a two-year storm can reduce peak
flows over 90 percent on the average flow of
that storm. Depending on the storage volume
and settling characteristics of suspended pol-
lutants, detention basins can reduce pollutant
loadings to downstream water bodies. NURP
found wet basins provide more water quality
benefits than dry basins. According to NURP,
wet basins have the greatest performance
capabilities, with pollutant reductions varying
mately $100 to $250 per acre for relatively large
urban areas. The costs include both capital and
initial operating costs; the range reflects differen-
ces in size needed to remove 50 to 90 percent
of particulates. Annual operating costs per acre
of urban area served are estimated at $60 to
$175 for on-site applications, and $10 to $25 for
off-site applications.18
from excellent to very poor in the basins that
were monitored. This variability in effectiveness
demonstrates that the design and the size of the
basin in relation to the urban area served are
critically important. As indicated by NURP data,
dry basins are essentially ineffective for reduc-
ing pollutant loads.
Wetlands and marshes have proven to act as
giant sponges in removing phosphorous and
suspended solids from runoff. It has been
demonstrated that a 7.5-acre wetland retained
77 percent ofall phosphorus and 94 percent of
total suspended solids draining from a 65-acre
sub-watershed of Lake Minnetonka, Minn.19
66
-------
Street cleaning practices include sweeping streets
and parking lots using mechanical vehicles or
flushing from tanker trucks. Sweeping handles
coarser dust and litter particles, whereas flushing
carries away the finer fractions.
Experience and Application
Sweeping is more common in the United States,
whereas street flushing is practiced mainly in
Europe. Street cleaning or sweeping actually
removes solids from the street, and therefore
reduces the volume, weight, and concentrations
of pollutants that can reach receiving waters.
Flushing does not remove the particles from the
street; it only moves the street refuse toward the
drainage system. For this reason, flushing has a
negligible effect on reducing pollution. However,
street flushing may be advantageous in areas
with combined sewer systems.
Capital and Operating Costs
Two types of sweepers are presently used to
remove solids from impervious urban surfaces.
The most common design is a mechanical
street cleaner that combines a rotating gutter
broom with a large cylindrical broom to carry the
material onto a conveyor belt and into the hop-
per. A vacuum-assisted street cleaner uses gut-
• Effectiveness
Studies indicate that street cleaning is most ef-
fective in controlling heavy metals, and
moderately effective in controlling oil and grease,
floating matter, and salts. Street sweeping has
not proven to be effective in controlling sediment,
nutrients, and oxygen-demanding materials.
The performance of a street cleaning program
depends on the condition of the street surface,
the particle size distribution of pollutants, the
amount of pollutants present initially, the num-
ber of passes per treatment, and the interval be-
tween treatments. Cars parked on congested
urban streets can reduce the effectiveness of
street sweeping to zero. Street flushing is not af-
fected by parked cars. In spite of relatively low
sweeper efficiencies, one study reported water
quality improved significantly in areas with
ter and main pickup brooms to loosen and move
street refuse into the path of a vacuum intake.
At present, a new mechanical street cleaner can
cost approximately $62,000, whereas a vacuum-
assisted street cleaner is slightly more ($68,000 -
$72,000). The average operator receives $9/hr.
regular sweeping practices. Water flushed from
unswept streets contained on the average 2.3
times more suspended solids and heavy metals
than that from swept and cleaned streets.20 Cur-
rent street sweeping is mostly for aesthetic pur-
poses, with sweepers removing little of the finer
dust and dirt fractions.
Based on five projects that evaluated street
sweeping as a management practice to control
pollutants in urban runoff, the Nationwide Urban
Runoff Program (NURP) found street sweeping
generally ineffective. Four of these projects con-
cluded that street sweeping was not effective for
this purpose and the fifth, which had a defined
wet and dry season, believed that sweeping just
prior to the rainy season could reduce some pol-
lution in urban runoff.
Street
Cleaning
urban and
construction
67
-------
Surface roughening is designed to decrease the
rate of water runoff by slowing the downhill
movement of water. It is routinely used at con-
struction sites. One type of surface roughening,
scarification, roughens the soil along the contour
of a graded slope. Grooves retain runoff and in-
crease the rate of water infiltration. Horizontal
grooves also retain soil additives, seeds, and
mulch that may be washed down the slope. Sof-
tening the soil also permits plant roots to
develop more readily. Other variations of soil
roughening include tracking and serrating slopes.
Experience and Application
This practice may be used where the physical
site requires some means of runoff control.
Scarification and serrating slopes are used
more commonly on gradual slopes, whereas
tracking is more adaptable on steep slopes.
Compacted surfaces from tracking may be
more beneficial on long, steep slopes exposed
to high rainfall. The construction sites should be
roughly graded as soon as possible after ex-
cavation to avoid the formation of soil mounds
that easily erode.
V'W^Svff
;-i/*ittM
Surface
Roughening
urban and
construction
69
-------
Surface
Roughening
urban and
construction
Capital and Operating Costs
Surface roughening is inexpensive to perform but
requires timing and coordination of construction
activities. Since these practices are carried out
with typical construction equipment (i.e., bulldoz-
ers), no additional equipment need be pur-
• Effectiveness
Construction typically disturbs areas by removing
vegetation and moving earth from one place to
another. Unprotected soils will be subject to
erosion unless pollution reduction controls are
chased. Areas disturbed during construction
can be roughened while the construction is
taking place, thus minimizing the cost of addition-
al labor to perform the erosion control practice.
practiced. Surface roughening is a very effec-
tive, cost-efficient method for preventing soil
erosion.
70
-------
Silviculture
-------
Limited disturbance restricts the areas where
work takes place to the most effective use of
space, personnel, and equipment at any given
time. An operational area may be defined by the
maximum number of active cut blocks, maximum
number of acres without seeding, or maximum
miles of roads without permanent erosion con-
trols.
Experience and Application
In large logging areas, it is especially useful to
limit the amount of space in which work is being
done. Exposing large areas of soil to direct rain-
fall may alter the soil's structure, reducing infiltra-
tion rates so that more rain becomes runoff and
overland flow. The use of large equipment also
compacts the soil, resulting in the same effects.
Capital and Operating Costs
This practice will generally not increase costs if it
is fully integrated into operations to make the
most effective use of equipment, labor, and
management. Operating costs may decline be-
cause management is concentrated on a
smaller area of operation.
Limiting
Disturbed
Areas
silviculture
73
-------
Limiting
Disturbed
Areas
silviculture
• Effectiveness
By limiting the logging operation to a clearly
defined area, greater control can be exercised
over the potential causes of nonpoint source pol-
lution, significantly reducing negative effects. The
clear area should be cleaned up as much as pos-
sible as the logging operation moves to the next
defined area. Restoration can begin as soon as
leftover material is disposed of, with reforesta-
tion proceeding even as the logging continues in
another area.
74
-------
Log transport (yarding) methods that move logs
from the felling location to a landing or transfer
point can vary drastically in their effect on the
environment. Yarding methods and the access
roads associated with them are primary causes
of erosion and sedimentation. Various log trans-
port methods include tractor, high lead, skyline
cable, balloon, and helicopter.
Experience and Application
Research has shown that silvicultural opera-
tions can temporarily change water quality
characteristics in streams draining forest land, in-
creasing sediment concentrations if erosion ac-
celerates, and stream temperatures if shade is
removed. Accumulations of slash (logging
debris) in a stream can deplete its dissolved
oxygen. Harvesting or application of pesticides
and fertilizers can increase organic and inorganic
chemical concentrations.21
Tractor skidding is the most common transport
method employed in the Northeast and South,
and on lands with less than 30 percent slope in
the Intermountain, Northwestern, and California
regions. To minimize scarification, a skid pan
and a high-wheeled arch yarder are commonly
used, sometimes with a winch to snake logs to
the tractor before skidding them to the yarding
area.
A high lead log transport system uses a
metal tower about 23 meters (75 feet) high
mounted on a mobile frame. Guy lines hold the
tower in place, from which a winch and set of
cables drag the logs along the ground to a yard-
ing area, where they are loaded into a truck.
Log
Removal
Techniques
silviculture
75
-------
Log
Removal
Techniques
silviculture
Skyline cable and balloons are recom-
mended for clearout logging operations. A
skyline cable system employs a cable to carry
the full weight of the logs as they are
transported. Aerial cables attached to the
towers at opposite ends of the logging site
mechanically lift the logs off the ground and
move them along the cable to the landing area,
which is usually near one of the towers. Skyline
cable systems are typically used for a large vol-
ume of timber and the system can operate at dis-
tances of more than 900 m (3,000 ft.). Cables
should be installed at a height that will ensure
that logs are lifted off of the ground during most
of the transport opertion.
The balloon method uses a large balloon
usually filled with helium and capable of static
lifts of 5 to 10 tons (4.5-9 metric). A cable system
similar to high lead is used to control the horizon-
tal movement of the balloon over the logging
site. A snubbing line may be required to winch
the unloaded balloon close to the ground. Bal-
loon logging is adapted to steep slopes (45 to
90 percent) with unstable soils. A minimum log-
ging yield of 70 m3 per hectare (12,000 board-
feet per acre) is necessary to justify this type of
log transport.
Helicopter log transport is recommended for
transporting valuable timber in inaccessible
areas where aesthetic values command high
priority. With this system, the helicopter lifts the
logs from the ground at the point of felling and
transports them to the loading area.
Capital and Operating Costs
Balloons and helicopters transport timber without
causing extensive soil erosion and sedi-
mentation, but they are more expensive than
the other techniques. Actual cost is difficult to
determine because balloons or blimp-like lifting
• Effectiveness
Tractor skidding is the worst technique in terms
of erosion control, and even on level to rolling
land tractors will expose more bare soil than
other methods. The pollution potential for high
lead log transport systems is generally less than
that for tractor skidding, although when logs are
repeatedly yarded over a high spot on the
ground, deep profile cuts into the soil may occur.
A skyline cable system has less potential for
pollution than the other two systems because it
requires only one-tenth as much road construc-
vehicles are only in the experimental stage in the
United States. Heavy lift helicopters are very ex-
pensive to purchase and maintain, and their use
has generally been restricted to more inacces-
sible terrain.
tion as more conventional methods. Lifting logs
off the ground, it thereby avoids cutting the
forest floor and confines soil disturbance to yard-
ing and loading areas.
Balloon and helicopter logging causes mini-
mal soil disturbance and erosion. Helicopter log-
ging requires fewer access roads and is a very
versatile system for moving logs from felling sites
to loading areas.
76
-------
Log Removal
Techniques
silviculture
77
-------
Maintaining ground cover in a disturbed area will
help prevent erosion while the vegetation even-
tually reestablishes. Grass, shrubs, small trees,
and sod provide good ground cover for forest
areas disturbed by logging.
Ground
Cover
silviculture
Experience and Application
In most situations, ground cover can be intro-
duced successfully to areas disturbed by log-
ging operations, usually after logging debris has
been removed from the ground. Grass cover
can be difficult to establish on arid or sterile
soils or on all slopes over 1:1. Jute mats or ex-
celsior pads may be required to hold seeds in
these critical areas.
Capital and Operating Costs
The costs incurred for this pollution manage-
ment practice include the purchase of plant
materials and fertilizer, and the labor for plant-
ing and applying the fertilizer.
79
-------
Ground
Cover
silviculture
• Effectiveness
Vegetation retains moisture, thus preventing dry
soil masses and saturation of the subsoils.
Vegetative ground cover also protects the soil
from heavy rainfall that may carry soil particles
downhill. This practice enhances infiltration and
reduces overland water flow, as it encourages
growth of vegetation required to return the site
to prelogging conditions.
80
-------
Debris such as tree tops and slash must be
properly disposed of away from waterways.
Streams near logging operations must be properly
and regularly checked for buildup of such debris,
to prevent it from damming the waterway and
scouring sediment from stream banks.
Experience and Application
In any work near waterways it is very important
to prevent build up of woody debris. 'Logging
operations may increase the amount of woody
debris in waterways, and it must be cleaned up
during and after timber harvesting. Although all
slash should be removed, the old debris
anchored in the streambed and around which the
channel has formed should be left in place.
Capital and Operating Costs
Ultimately, this management practice should cost
nothing. The only requirement is enough super-
vision over logging operations to ensure the
proper removal and disposal of debris.
When cleanup has been necessary, hand
• Effectiveness
Maintaining stream channels by preventing the
buildup of debris from logging activities will sig-
nificantly reduce the impact on the water
cleaning costs were estimated at $160 to $800
(updated to 1985 dollars) per 100 foot of
stream, averaging about $500 per station when
about 5 tons of material were removed.22
course. Debris that deflects or constricts
waterflow accelerates bank and channel
erosion.
Removal
of Debris
silviculture
81
-------
Construction, use, and maintenance of access
roads and skid trails expose the ground surface to
rainfall and can alter drainage patterns to intensify
erosive forces. Appropriate location and design
of haul roads will help prevent erosion in disturbed
areas.
Experience and Application
Logging roads must be constructed properly to
prevent nonpoint source pollution. Roadways
should be built away from water courses and ac-
cording to recommended guidelines for
gradient, drainage, soil stabilization, and filter
strips in the area. Where possible, roads should
be routed across, rather than up and down
slopes, with artificial drainage where normal pat-
terns are disrupted seriously. Use should be
restricted during wet weather. Skid trails should
be limited in number and avoided when logging
on very steep grades.
Capital and Operating Costs
Although road construction may cost the logging
company a great deal before operations begin,
it is very important to provide a roadway that
functions as a route for tree removal and also
causes the least environmental impact. Road
surfacing will affect operating cost. In one study,
grass (plus fertilizer) cost $5.37/30 m roadbed;
crushed rock (15 cm), $179.01/30 m roadbed;
and 20 cm rock, $265.67/30 m roadbed.23 Gras-
ses may be cheaper but may require more main-
tenance and periodic replanting.
Proper
Roads
and Trails
silviculture
83
-------
Proper
Roads
and Trails
silviculture
• Effectiveness
Properly designed and constructed road and skid
trails help pre- vent erosion in forest areas.
Roadways must be designed to consider
erosion potentials from various cross sections of
the road, choosing a crown-with-ditch-and-cul-
vert design that has the least impact on the
area. Roads must be graded and aligned to mini-
mize mileage on steep slopes.
Road coverings such as grass or gravel also
reduce sediment loss. A study discovered that
losses of sediment from roadbeds without sur-
face covering were eight times the losses from
roadbeds covered by 15-20 cm gravel.24 In a
study of types of coverings, the mean soil loss
rates on five mountainous roadways were es-
timated as follows:
• bare soils, 1.2 ton/ha roadbed/cm rain
• grass, 0.65 ton/ha roadbed/cm rain
• crushed rock (15 cm), 0.1 ton/ha road-
bed/cm rain.25
Adequate gravel cover will last for several
years whereas grasses must be replenished
routinely and may not be effective on highly
traveled roads.
Good practices include closing temporary tim-
ber access roads when not in use, closing roads
during wet periods of the year to prevent sedi-
ment from being produced, and—when logging
operations cease—restoring the main haul
roads to conditions that will prevent erosion.
84
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Mining
-------
Water diversion involves collecting the water
before it enters the mine, then conveying it
around the mine site. Ditches, flumes, pipes,
trench drains, and dikes are commonly used for
water diversion. Riprap and dumped rock are
sometimes used to reduce water velocity in the
conveyance system. Ground water can be
diverted by using a well to intercept it and then
pump it away from its normal flow path before it
enters the mine, or by using drainways to carry
the ground water out of the mine before it con-
tacts pollution-forming materials.
Experience and Application
A water diversion system should be properly
designed to accommodate expected volumes
and water velocities. If the capacity of a ditch is
exceeded, water can erode the sides and
render the diversion structure useless for any
amount of rainfall. Ditches are usually ex-
cavated upslope of the surface mine. Flumes
and pipes are used to carry water down steep
slopes or across regraded areas. Surface water
diversion can be applied to many waste piles,
diverting water around or conveying it via closed
channels through the waste material.
Capital and Operating Costs
Costs vary according to the site, the type of
mine and operation, and the design and
materials used. However, water diversion
reduces water treatment costs by reducing the
• Effectiveness
Surface water diversion is an effective techni-
que for preventing water pollution: it can be ap-
plied to almost any surface mine orwaste pile.
volume of water that needs to be treated. Where
ground water is concerned, it may be cheaper to
drill holes and pump ground water away than to
treat the water after it passes through the mine.
This procedure decreases erosion and reduces
pollution.
Water
Diversion
mining
87
-------
Underdrains of tile, rock, or perforated pipe can
be placed below pollution-forming materials to
quickly discharge infiltrating water. These
devices shorten the flow path and residence time
of water in the waste materials.
Experience and Application
Underdrains are designed to provide zones of
high permeability to collect and transport water
from the bottom of the piles. A common construc-
tion method is to use trenches filled with rock.
Underdrains can be used with large tailings ac-
• Capital and Operating Costs
Construction should be relatively inexpensive,
higher if the underdrains must be installed in ex-
isting waste piles.
• Effectiveness
Underdrains are recommended for use with
head-of-hollow mining technique, but should not
be used where the pile has been inundated, be-
cause the underdrains will drain the pile and
cumulations, but should be installed before the
pile is created. Care must be taken during design
to preclude the possibility of fines clogging the
underdrain. Filter fabric is used for this purpose.
cause adverse effects. Underdrains should be
used only in piles where the water table fluc-
tuates and flow is in direct response to rainfall.
Underdrains
mining
89
-------
The block-cut method is a simple innovation of the
conventional contour strip mining method for
steep terrain. Instead of casting the overburden
from above the coal seam down the hillside, it is
hauled back and placed in the pit of the previous
cut. No spoil is deposited on the downslope below
the coal seam, topsoil is saved, overburden is
removed in blocks and deposited in prior cuts,
the outcrop barrier is left intact, and reclamation is
integrated with mining.
Experience and Application
Once the original cut has been made, mining can
be continuous,working in either one or both
directions around the hill. The cuts are mined as
units, thereby making it easier to retain the
original slope and shape of the mountain after
mining. In all cuts, an unmined outcrop barrier
is left to serve as a notch to support the toe of the
backfilled overburden.
Capital and Operating Costs
The block-cut method is no more expensive and
may be less than conventional dragline pull-
back mining—an estimated 33 cents per ton
• Effectiveness
Block-cut mining makes it possible to mine on
steeper slopes without the danger of slides and
with minimal disturbance: approximately 60 per-
cent less total acreage is disturbed than by
other mining techniques. There is significant
visual evidence that the block-cut method is less
damaging than the old practice of shoving over-
burden down the side of the mountain. The
less in Pennsylvania. Reclamation costs are
lower, as the overburden is handled only once in-
stead of two or three times.
treeline below the mined area and above the
highwall is preserved, with results of the opera-
tion generally hidden from view. Landslides
caused by spoil on the downslopes have been
totally eliminated. Erosion is significantly reduced
and more easily controlled because of concur-
rent reclamation with mining.
Block
Cutting
mining
91
-------
Multicategory
-------
Buffer zones are strips of grass or other erosion-
resistant vegetation planted between a waterway
and intensively-used land. Buffer strips can be lo-
cated on the edges of fields or along stream-
banks. Grass buffer strips reduce the velocity of
runoff and cause suspended sediments to settle
out of storm flows. Buffer strips reduce nonpoint
pollution from agricultural, construction, and sil-
vicultural activities.
Experience and Application
Vegetative strips trap sediment and pollutants in
surface runoff because they retard water flow,
thereby increasing infiltration and detention of
paniculate matter. This technique is applicable
to all areas where streams, lakes, and open
channels exist.
Grass filter strips provide excellent trapping ef-
ficiency for suspended solids, especially for con-
• Capital and Operating Costs
Buffer strips require moderate expenditures to
implement and should be incorporated as
needed along natural waterways.
struction sites and farms. Grass strips can also
be used to control barnyard and feedlot runoff
and to reduce soil and pollutant loss from agricul-
tural fields. This BMP does not address the
source of pollutants, and may remove agricul-
tural land from production and valuable land from
development.
• Effectiveness
A 2.5 m grass strip can remove a minimum of 85
percent sediment during shallow overland flow.
Although effective in controlling erosion, most
grassed areas do not reduce pollution. Grass
buffer strips have been used only recently to
control agricultural pollution, and, like grassed
waterways, more research is needed to quantify
their effectiveness. Cropped buffer strips on a 4
percent slope have reduced feedlot runoff by 67
percent and runoff of total solids by 79 percent.
In the same study, movement of nitrogen and
phosphorus in the runoff decreased by an
average of 84 and 83 percent, respectively.
Buffer
Strips
multicategory
95
-------
Grassed waterways are natural or constructed
drainage channels used to conduct surface
runoff. The waterways are usually broad and shal-
low, covered with erosion-resistant grasses.
Agricultural grassed waterways are used for safe
disposal of runoff from fields, diversions, and ter-
races, and for other conservation measures. Also,
grassed waterways serve as nonpoint pollution
control in residential and construction areas.
Experience and Application
Grassed waterways are a basic conservation
practice commonly used by farmers. The ideal
location for a waterway is a well-vegetated
natural draw; however, this technique can be
used only on up to 80 percent of all cropland. A
pasture or meadow strip lying in a drainageway
may be used instead of a constructed or natural
waterway. The waterway design should ensure
that the strip is wide enough to carry the volume
of flow, and that the type and density of vegeta-
tion are adequate to withstand expected flow
velocities. Vegetative cover such as reed canary
grass and Kentucky 31 tall fescue (unmowed)
provide excellent cover.
Grassed
Waterways
multicategory
97
-------
Grassed
Waterways
multicategory
Capital and Operating Costs
Although the cost to implement grassed water-
ways is moderate, this technique is probably the
most effective and economic means of convey-
ing water. If waterways are designed properly, in-
channel erosion should be minimal, and the
grass lining may even serve as a sediment trap.
• Effectiveness
Agricultural grassed outlets facilitate drainage of
graded rows and terrace channels with minimal
erosion. By encouraging drainage, this practice
increases runoff volume and decreases soil in-
filtration. Grassed waterways also allow for dis-
Agricultural grassed outlets involve costs to es-
tablish and maintain and may interfere with the
use of large equipment. Some shaping or enlarg-
ing may be required to handle the increased
flow; if this is the case, the design and construc-
tion should provide a stable channel.
posing of excess surface water from construction
sites and urban areas without causing erosion.
Grassed waterways can prevent 60 to 80 percent
of suspended particles from moving to adjacent
surface waters.
98
-------
The most popular method of increasing infiltra-
tion—the gradual downward movement of water
from the surface into the subsoil—is through
trenches or ponds. Trenches usually are shallow
excavations with a permeable bottom material
such as gravel or sand laid over a permeable sub-
strate, thereby allowing runoff water to percolate
freely into the ground water. Other ways to in-
duce infiltration include dry wells, wet and dry
ponds, evaporation ponds, and special impound-
ments. Infiltration systems are used to control
runoff along highways and manage storm water in
urban developments. (See Runoff Detention/Re-
tention).
Experience and Application
Infiltration devices can be an acceptable ap-
proach to managing stormwater runoff, but they
must be limited to good quality storm water so
as to prevent contamination of the ground water.
In addition, adequate clearance must be main-
tained between the bottom of the structure and
the groundwater table. Some type of sediment
trap should be provided to remove sediment and
other debris from the runoff before it enters the
infiltration area.
Infiltration systems can replenish ground
water and increase stream flows during low flow
periods. Their use depends on soil permeability,
aquifer conditions, and the topography as well
as the depth of the groundwater table. A pervious
subsoil is necessary to dispose of water at an
adequate rate.
Infiltration
Devices
multicategory
99
-------
Infiltration
Devices
multicategory
Capital and Operating Costs
These systems may require a high degree of main-
tenance because of the tendency of the coarse bot-
tom material to clog with fine particles. This can be
• Effectiveness
Increased infiltration improves recharge into
groundwater aquifers. In addition, infiltration may
corrected by routing the water over grass, vegeti
tive Alters, or sediment traps before it enters the ii
filtration area.
totally remove fine soil particles and other partici
lates as well as dissolved solids.
100
-------
Diversion structures are conveyances designed to
change the direction of water flow. They represent
any modification of the surface that intercepts and
diverts runoff while increasing the distance of
flow to a larger channel system. Basically, diver-
sion structures are designed to intercept runoff
before it has a chance to come in contact with an
erodible soil surface. Diversion structures include
soil or stone dikes, ditches (or swales), terraces,
and benches. These structures can be tem-
porary or permanent and should not cause in-
channel erosion. They often are constructed to
divert up-slope runoff from a source of nonpoint
pollution (disturbed area), and can be used on
construction sites, urban areas, or agricultural
lands.
Interception/
Diversion
Practices
multicategory
101
-------
Interception
Diversion
Practices
multicategory
Experience and Application
Diversion structures may be used to protect bot-
tom land from hillside runoff, divert water from
areal sources of pollution, or protect structures
from runoff. This technique is particularly ap-
plicable on slopes up to 12 percent and above
feed lots on any slope. The diversion structure
should allow a shallow, random flow. It can also
be used at the top of graded slopes to divert of-
fsite runoff away from an erodible surface. For
example, this technique has been used to a
great extent to divert runoff along highways.
Diversion structures can be used in urban
developments, but require an adequate
analysis of the hydrology, geology, and soils in
the area. On agricultural lands, they are general-
ly built above cropland fields, gully headcuts, or
other critical erosion areas. Other BMPs should
be used in areas subject to slumping and
landsliding.
Diversion structures should have adequate
outlets that will convey runoff without causing
erosion, such as natural or constructed
vegetated outlets capable of safely carrying the
discharge, properly designed and constructed
grade stabilization structures, or storm sewers.
If the diversion structure is used to collect runoff
from a disturbed area, its outlet should open
into a sediment trap or basin. Disadvantages of
using this technique: it may interfere with cultiva-
tion, maintenance may be required, and it is
relatively costly.
Capital and Operating Costs
Diversions require some engineering design
and structure, and could be more expensive
than source controls. The cost of a diversion
• Effectiveness
This technique can be a very effective way of
preventing excessive erosion, but only if it is
designed, installed, and maintained correctly.
Diversion structures can reduce pollutants (par-
ticularly total phosphorus, suspended solids,
structure could vary greatly from an inexpensive
earth channel to a large concrete diversion.
pesticides and total nitrogen) entering adjacent
water bodies from 30 to 60 percent. The struc-
ture's effectiveness depends on the physical
characteristics of the development site as well
as climatic factors.
102
-------
Loose rock, aggregate, mulches, or fabric can be
layered over an erodible soil surface, providing
an excellent erosion control for all nonpoint sour-
ces.
Experience and Application
Riprap, the common term for loose rock or ag-
gregate, is used where soil conditions, water tur-
bulence and velocity, expected vegetative
cover, and groundwater conditions are such that
soil may erode under certain flow conditions.
Riprap may be used at such places as storm
drain outlets, channel banks and bottoms, road-
side ditches, lake shores, and drop structures.
The area to be riprapped can be shaped with
heavy equipment or the rock can be placed along
the bank without any bank modification. Vinyl or
geo-fabric materials, often of fine mesh construc-
tion, should be placed beneath riprap to prevent
flowing water from pulling sediments through
voids in the riprap.
Deflectors constructed of large rocks, logs, or
wire mesh (gabions) also can be put in place to
control water flow.
Capital and Operating Costs
The cost of using one of these materials to
prevent erosion could vary tremendously,
depending on the type and availability of the
material, whether or not the site must be
modified by heavy equipment, and how large an
area needs to be covered. The initial cost of
Material
Ground
Cover
multicategory
103
-------
Material
Ground
Cover
multicategory
material varies from State to State and from com-
munity to community. A good example of the
variability in the cost of riprapping was
demonstrated in 1982 on three South Dakota
Lakes (Lake Kampeska, Oakwood, and Swan)
under EPA's Clean Lakes Program. In summary,
Lake Kampeska cost $39 per foot of shoreline,
• Effectiveness
The materials described can be very effective in
reducing erosion on unstable banks. A good ex-
ample of the effectiveness of riprap was dem-
onstrated on the South Dakota Lakes where, in
Oakwood Lake cost $38.50 per foot of shore-
line, and Swan Lake cost $5.22 per foot of
shoreline. The low cost of riprapping Swan Lake
can be attributed to the extensive local donations
and the fact that little or no reshaping was done
to the shoreline prior to riprapping.27
all three cases, visual inspections have con-
cluded that the riprap has protected severely
eroded shorelines and is expected to dis-
courage further erosion.
104
-------
Sediment traps are small, temporary structures
used at various points within or near disturbed
areas to detain runoff for a short period and trap
coarser sediment particles. They are generally
thought of as smaller detention structures used
to trap the coarser sediment. Various types of
sediment traps include sandbags, straw bales,
stone or prefabricated check dams, log and pole
structures, excavated ditches, and small pits. A
structure called a stone trap can be placed
across stream channels to temporarily detain
flow and trap sediment. This type of trap consists
of a dike of randomly placed stone, sized accord-
ing to expected flow rates.
Experience and Application
Sediment traps are considered on-site prac-
tices. Traps may be placed around storm drain
inlets and in ditches and other small drainage
ways. Sediment should be removed and the
trap restored to its original dimensions when the
accumulated sediment reaches 50 percent of
the trap's depth.
Sediment
Traps
multicategory
105
-------
Sediment
Traps
multicategory
Capital and Operating Costs
Sediment traps are usually inexpensive to build
and can be incorporated into any construction
project. Although sediment traps must be in-
• Effectiveness
When these structures are positioned at regular
intervals along a drainage way or at storm drain
inlets, a high degree of trapping efficiency for
spected occasionally, cleaned periodically, and
promptly maintained if they are to function ade-
quately, such costs are minimal.
coarser particles can be achieved. They have lit-
tle effect on retaining fine soil particles and their
associated pollutants.
106
-------
Vegetation can be established to stabilize the
soil either temporarily or permanently. Tem-
porary stabilization uses fast-growing annual
and perennial plants that provide interim protec-
tion for less than a year. Permanent stabilization
uses long-lived perennial plants. Selected accord-
ing to specific site conditions, these plants in-
clude grasses, legumes, ground cover, vines,
shrubs, and native herbaceous plants and trees.
Areas around vegetative cover can be mulched
(with plant residues) or geo-fabrics can be in-
stalled to further reduce erosion and protect the
ground. Vegetative stabilization and mulching
are applicable to agricultural, construction,
urban, mining, and silvicultural areas.
Vegetative
Stabilization
multicategory
107
-------
Vegetative
Stabilization
multicategory
Experience and Application
Vegetation is a very desirable material for con-
trolling soil erosion. Vegetative cover performs a
number of important functions, including shield-
ing the soil from the impact of the raindrops,
retarding surface flow of water and thereby per-
mitting greater infiltration, maintaining a per-
vious soil surface capable of absorbing water,
and removing water from the soil between storm
events by transpiration. The installation of plant
material requires good soil preparation and
proper planting techniques. Site factors that may
prevent plants from becoming established on ex-
posed materials typical of construction sites in-
clude the chemical and physical properties,
steepness of slopes, and the site's biological fea-
tures.
Grasses and legumes are considered superior
to trees, shrubs, and ground covers for initial
soil stabilization because their fibrous root sys-
tems characteristically bind soil particles, en-
courage the formation of water-stable soil ag-
gregates, protect the soil surface from erosion by
water and wind, and grow quickly. Vegetative
cover not only reduces pollution to lakes and
streams but improves the aesthetics of the en-
vironment and, where desirable, provides
wildlife habitat.
Capital and Operating Costs
The cost of vegetative stabilization varies greatly,
depending on the size of the area to be stabilized
and the difficulty of surface preparation as well as
the type of vegetation used. Ground cover
along highways can be much less costly than
elaborate landscape design incorporated into
urban developments. After the vegetative cover
• Effectiveness
Vegetation in any form is a very effective means
of controlling soil erosion. However, the condition
of the installed vegetation will determine its effec-
tiveness. For example, a cover of vegetation
that is not properly established or maintained
will not be fully effective in controlling erosion.
becomes established, regular maintenance is re-
quired to achieve a long-term cover that ade-
quately controls soil erosion. However, plant
materials vary in the amount of maintenance re-
quired to sustain them. For example, on inacces-
sible slopes, a low maintenance cover would be
desirable.
Various grass species reduce soil loss by 95 to
99 percent compared to bare surfaces. Overall,
research must continue into determining the ef-
fectiveness of vegetative stabilization as an
erosion control practice.
108
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109
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End Notes
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2Novotny, V., and G. Chesters. 1981. Handbook of
Nonpoint Pollution Sources and Management. Van
Nostrand Reinhold Environmental Engineering
Series, New York.
2'3Conservation Tillage Information Center. 1986.1985
National Survey Conservation Tillage Practices Ohio
County Summary. Natl. Ass. Conserv. Distr.
"Mueller, D, T. Daniel, and R. C. Wendt. 1981. Con-
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5Loehr, R. C. 1984. Pollution Control for Agriculture.
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6Yaksich, S. M. 1983. Summary report of the Lake
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tional Joint Commission. Windsor, Ontario.
"Onstad, C. A. and T. C. Olson. 1970. Water budget
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11Novotny, V., and G. Chesters. 1981. Handbook of
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12Wendt, R. C., and R. E. Burwell. 1985. Runoff and
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J. Soil Water Conserv. Sept.-Oct. 450-4.
13Report to the Great Lakes Water Quality Board.
1983. Nonpoint source abatement in the Great Lakes
basin. An overview of post— PLUARG development.
International Joint Commission. Windsor, Ontario.
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18U.S. Environmental Protection Agency. 1983.
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ecutive summary. Water Planning Division, U.S. En-
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19Hickock, E. A., M. C. Hannaman, and N. C. Wenck.
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20Malmquist, Per-Arne. 1978. Atmospheric fallout and
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21 Brown, G. W. 1985. Controlling nonpoint source pol-
lution from silvicultural operations: What we know and
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22Dykstrat, DP., and H.A. Forehlich. 1976. Cost
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Forestry October: 684-7.
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30(3):657-70.
26Young, R., T. Huntrods, and W. Anderson. 1980. Ef-
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27 Final Report: Swan lake restoration project. 1982.
110
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Glossary
Aeration of lawns - Periodic perforation of lawns to
increase infiltration. Usually performed by punching
holes into the lawn by mechanical means. Urban
lawns have very low infiltration rates in comparison to
woods and grasslands.
Best management practices (BMPs) - Measures,
sometimes structural, that are determined to be the
most effective, practical means of preventing or reduc-
ing pollution inputs from nonpoint sources to water
bodies.
Buffer strip or zone - Strips of grass or other erosion-
resistant vegetation between a waterway and an area
of more intensive land use.
Calibration (Model) - Determination of some model
parameters that depend on the application (site,
process, etc.).
Chisel plowing - Seedbed preparation by plowing
(with a chisel cultivator or chisel plow) without com-
plete inversion of the soil, leaving a protective cover
of crop residues on the surface for erosion control.
Combined sewer - A sewer receiving both inter-
cepted surface runoff and municipal sewage.
Conservation tillage - Any tillage and planting sys-
tem that maintains at least 30 percent of the soil sur-
face covered by residue after planting to reduce soil
erosion by water; where soil erosion by wind is the
primary concern, maintains at least 1,000 pounds of
flat, small grain residue equivalent on the surface
during the critical erosion period.
Contour farming - Conducting field operations, such
as plowing, planting, cultivating, and harvesting on
the contour (across the slope).
Contour stripcropping - Farming operations per-
formed on the contour with crops planted in narrow
strips.
Conventional tillage - Standard method of preparing
a seedbed by completely inverting the soil and incor-
porating all residues with a moldboard plow. The
field is gone over more than once in order to prepare a
smooth, fine surface.
Cover crop - A close-growing crop grown primarily
for the purpose of protecting and improving soil be-
tween periods of regular crop production or between
trees and vines in orchards and vineyards.
Crop residue - The portion of a plant or crop left in the
field after harvest.
Crop rotation - The growing of different crops in
recurring succession on the same land, as opposed
to continuous culture of one crop.
Detention - The slowing of flows-either entering the
sewer system or draining over the surface-by tem-
porarily holding the water on a surface area in a
storage basin or within the sewer.
Detention dam - A dam constructed for temporary
storage of stream flow or surface runoff and for releas-
ing the stored water at controlled rates.
Diversion- Individually designed conveyances across
a hillside. They may be used to protect bottom land
from hillside runoff, divert water from areal sources of
pollution or protect structures from runoff.
Ecology - Interrelationship between organisms and
the environment.
Ecosystem (ecological system) - a functional sys-
tem that includes the organisms of a natural com-
munity together with their environment.
Erosion - The wearing away of the land surface by
running water, wind, ice, or other geological agents.
Eutrophication - The process of enrichment of water
bodies by nutrients. Eutrophication of a lake normally
contributes to its slow evolution into a bog or marsh
and ultimately to dry land. Eutrophication may be ac-
celerated by human activities.
Filter berm - A large stone or gravel dike placed
across graded areas where runoff concentrates or at
the disposal points along diversion dikes.
First flush - The condition, often occurring in storm
sewer discharges and combined sewer overflows, in
which a disproportionately high pollutional load is car-
ried in the first portion of the discharge or overflow.
117
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Gravel inlet filter - A pile of stone or gravel placed
around or in front of an inlet to a culvert or other type
of drainage device.
Grassed waterway - A natural or constructed water-
way (usually broad and shallow covered with erosion-
resistant grasses) used to conduct surface runoff.
Ground cover - Any vegetation producing a protect-
ing mat on or just above the soil surface. In forestry,
low-growing shrubs, vines, and herbaceous plants
under the trees.
Ground water - Subsurface water in the zone of
saturation.
Herbicide - A chemical substance used for killing
plants, especially weeds.
Impoundment - Generally an artificial collection or
storage of water, as a reservoir, pit, dug out, sump,
etc.
Infiltration - The gradual downward movement of
water from the surface into the subsoil.
Intensive cropping - Maximum use of the land by
means of frequent succession of harvested crops.
Leaching - The removal of materials in solution from
the soil.
Minimum tillage - See reduced tillage.
Model - A set of algorithms organized in a logical
structure that represents a process.
Mulch - Any material such as straw, sawdust, leaves,
plastic film, etc., that is spread on the surface of the
soil to protect the soil and plant roots from the effects
of raindrops, freezing, evaporation, etc.
Mulch-till - The total soil surface is disturbed by tillage
prior to planting. Tillage tools such as chisels, field
cultivators, discs, sweeps, or blades are used. Weed
control is accomplished with a combination of her-
bicides and cultivation.
Nonpoint source (NPS) pollution - Pollution caused
by sediment, nutrients, and organic and toxic substan-
ces originating from land-use activities and/or from
the atmosphere, which are carried to lakes and
streams by runoff. Nonpoint source pollution occurs
when the rate at which these materials entering water
bodies exceeds natural levels.
No-tillage - A method of planting crops that involves
no seedbed preparation other than opening the soil
for the purpose of placing the seed at an intended
depth. This usually involves opening a small slit or
punching a hole into the soil. Planting is completed in
a narrow seedbed approximately 1-3 inches wide.
Chemical weed control is normally used. Also referred
to as "zero tillage" or "no-till."
Nutrients - Elements or substances, such as nitrogen
or phosphorus, that are necessary for plant growth.
Large amounts of these substances reaching water
bodies can become a nuisance by promoting exces-
sive aquatic algae growth.
Pesticide - Any chemical agent used for control of
specific organisms; such as insecticides, herbicides,
fungicides, etc.
Plow-plant - Plowing and planting a crop in one
operation, with no additional seedbed preparation.
Point source pollution - This type of water pollution
results from the discharges into receiving waters from
sewers and other identifiable "points." Common point
sources of pollution are discharges from industries and
municipal sewage treatment plants.
Porous pavement - A surface that will allow water to
penetrate through and percolate into soil (porous as-
phalt pavement). Pavement is comprised of irregular
shaped crush rock precoated with asphalt binder.
Water seeps through into lower layers of gravel for
temporary storage, then filters naturally into the soil.
Reduced tillage - Any tillage system that involves
less soil disturbance and retains more plant residue on
the surface than conventional tillage. Any tillage and
planting system that meets the 30 percent residue re-
quirement. Sometimes called "conservation" or "mini-
mum" tillage. Common practices include plow-plant-
ing, double-disking, chisel plowing, and strip tillage.
Retention - The prevention of runoff from entering
the drainage system by storing it on a surface area or
in a storage basin.
Ridge till - The soil is left undisturbed prior to planting.
Approximately 1/3 of the soil surface is tilled at plant-
ing with sweeps or row cleaners. Planting is com-
pleted on ridges usually 4-6 inches higher than the row
middles. Weed control is accomplished with a com-
bination of herbicides and cultivation. Cultivation is
used to rebuild ridges.
Riprap - A facing layer or protective mound of stones
placed to prevent erosion or sloughing of a stream-
bank or embankment.
Row crop - A crop planted in rows, normally to allow
cultivation between rows during the growing season.
Runoff - The portion of rainfall, melted snow, or irriga-
tion water that flows across the surface or through un-
derground zones and eventually runs into streams.
The runoff has three components: surface runoff, in-
terflow, and groundwater flow. Runoff may pick up pol-
lutants from the air or the land and carry them to
receivingwaters.
Sediment - Transported and deposited particles
derived from rocks, soil, or biological materials.
Sedimentation - Erosion, transport, and deposition
of detached sediment particles by flowing water or
wind.
Serrating - Serrations made on the contour on cut
slopes by conventional bulldozers at varying intervals.
Simulation - The process that mimics some or all of
the behavior of one system with a different, dissimilar
system, particularly with computers or models.
118
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Slash - Debris from logging activities littering a clear-
ing in a forest.
Slumping - To sink down suddenly or collapse.
Skid trails - Ruts caused by dragging logs from stump
area to loading station.
Stochastic - Pertaining to random variables (statisti-
cal).
Storm sewer - A sewer that carries only surface
runoff, street wash, and snow melt from the land.
Storm sewers are completely separated from those
that carry domestic and industrial and commercial
wastewater.
Stripcropping - The crop growing practice that re-
quires different types of tillage, such as corn and alfal-
fa, in alternate strips.
Strip-till - The soil is left undisturbed prior to planting.
Approximately 1/3 of the soil surface is tilled at plant-
ing time. Tillage in the row may consist of a rototiller,
in-row chisel, row cleaners, etc. Weed control is ac-
complished with a combination of herbicides and cul-
tivation.
Stubble mulch - The stubble of crops or crop
residues left essentially in place on the land as a sur-
face cover during fallow and the growing of a succeed-
ing crop.
Surface roughening - Any practice that provides for
rougher, more permeable surfaces that will slow
runoff velocity and reduce erosion potential. Porous
pavements, grassed, and gravel driveways are ex-
amples.
Surface runoff - Precipitation excess that is not
retained on the vegetation or surface depressions
and is not lost by infiltration, and thereby is collected
on the surface and runs off.
Terraces- An embankment, or combination of an em-
bankment and channel, constructed across a slope to
control erosion by reducing the slope and by diverting
or storing surface runoff instead of permitting it to flow
uninterrupted down the slope.
Tillage - The operation of implements through the
soil to prepare seedbeds and rootbeds.
Tilth - The state or degree of being tilled.
Time Series - A series of chronologically ordered
values giving a discrete representation of the varia-
tion in time of a given entity.
Tracking - Moving a cleated dozer up and down a
graded slope to provide a roughened, serrated slope.
More adaptable to steep slopes than scarification and
serrating.
Urban runoff - Surface runoff from an urban
drainage area that reaches a stream or other body of
water or a sewer.
Validation (Models) - The testing of a model for com-
pliance with existing data or information.
Watershed - The total land area drained by a stream,
lake, or river system. Also, the area of land that con-
tributes runoff of a given point in a drainage system.
Wheel-track planting - Plowing and planting in
separate operations with the seed planted in the wheel
tracks.
Windbreak - A living barrier of trees or combination
of trees and shrubs located adjacent to farm or ranch
headquarters and designed to protect the area from
erosion, winds and drifting snow. Windbreaks also
may be used in urban and recreational settings, and
to protect livestock.
Wind erosion - The detachment and transportation
of soil by wind.
119
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Index
AGNPS 13
ANSWERS 14
ARM 15
Block Cutting 91
Buffer Strips 95
Conservation Tillage 37
Contouring 39
Cover Crops 43
COWFISH 17
CREAMS 16
ESRFPP 19
Fertilizer Management 45
GAWS 21
GLEAMS 20
Grassed Waterways 97
Ground Cover 79
HSPF 23
Infiltration Devices 99
Integrated Pest Management 47
Interception/Diversion Practices 101
Limiting Disturbed Areas 73
Log Removal Techniques 75
Material Ground Cover 103
Nonvegetative Soil Stabilization 61
NPS 25
NURP 26
Porous Pavement 63
Proper Roads and Trails 83
Range and Pasture Management 49
Removal of Debris 81
Runoff Detention/Retention 65
Sediment Traps 105
Sod-Based Crop Rotation 51
Street Cleaning 67
Stripcropping 41
Structural Controls 59
Surface Roughening 69
SWAM 30
SWMM-Level 1 27
SWMM-Simplified 28
SWMM 29
Terracing 53
Underdrains 89
Vegetative Stabilization 107
Waste Management 55
Water Diversion 87
WRENS 31
121
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