United States

Department of

Agriculture

Natural

Resources

Conservation

Service

Agriculture

Handbook

Number 590

Ponds —

Planning, Design,

Construction
i

Agriculture Handbook 590 Ponds—Planning, Design, Construction Preface

This handbook describes the requirements for building a pond. It is useful

to the landowner for general information and serves as a reference for the

engineer, technician, and contractor.

In fulfilling their obligation to protect the lives and property of citizens,

most states and many other government entities have laws, rules, and

regulations governing the installation of ponds. Those responsible for

planning and designing ponds must comply with all such laws and regulations. The owner is responsible for obtaining permits, performing necessary

maintenance, and having the required safety inspections made.
ii

Agriculture Handbook 590 Ponds—Planning, Design, Construction Acknowledgments

The first version of this handbook was prepared under the guidance of

Ronald W. Tuttle, national landscape architect for the USDA, Natural

Resources Conservation Service (NRCS), and Gene Highfill, national

agricultural engineer (retired), NRCS, Washington, DC.

This version of the handbook was prepared by Clifton Deal, soil mechanic

engineer, NRCS Portland, Oregon; Jerry Edwards, hydraulic engineer

(retired), NRCS, Columbia, Missouri; Neil Pellmann, agricultural engineer,

NRCS, Columbia, Missouri; Ronald W. Tuttle; and under the guidance of

Donald Woodward, national hydrologist, NRCS, Washington, DC.

The appendixes material was originally prepared for Landscape Architecture Note 2—Landscape Design: Ponds by Gary Wells, landscape architect,

NRCS, Lincoln, Nebraska.

Mary R. Mattinson, editor; Lovell S. Glasscock, editor; John D.

Massey, visual information specialist; and Wendy R. Pierce, illustrator;

NRCS, Fort Worth, Texas, provided valuable assistance in preparing the

document for publishing.
iii

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Introduction 1

Water needs 2

Livestock ............................................................................................................ 2

Irrigation ............................................................................................................ 3

Fish production ................................................................................................. 3

Field and orchard spraying .............................................................................. 4

Fire protection .................................................................................................. 4

Recreation .......................................................................................................... 6

Waterfowl and other wildlife ........................................................................... 6

Landscape quality ............................................................................................. 6

Multiple purposes ............................................................................................. 8

Preliminary investigations 9

General considerations .................................................................................... 9

Area adequacy of the drainage ........................................................................ 9

Minimum pond depth ..................................................................................... 10

Drainage area protection ............................................................................... 11

Pond capacity .................................................................................................. 12

Landscape evaluation ..................................................................................... 12

Estimating storm runoff 13

Hydrologic groupings of soils........................................................................ 13

Runoff curve numbers .................................................................................... 13

Volume of storm runoff .................................................................................. 18

Rainfall amounts and expected frequency .................................................. 19

Rainfall distribution ........................................................................................ 19

Peak discharge rate ........................................................................................ 20

Time of concentration .................................................................................... 20

Average watershed slope ............................................................................... 21

Flow length ...................................................................................................... 21

Ia /P ratio .......................................................................................................... 21

Estimating peak discharge rates ................................................................... 22

Site surveys 24

Contents

Ponds — Planning, Design,

Construction

Agriculture Handbook 590
iv

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Embankment ponds 24

Detailed soils investigation ............................................................................ 24

Spillway requirements .................................................................................... 26

Pipes through the dam ................................................................................... 36

Planning an earthfill dam ............................................................................... 45

Staking for construction ................................................................................ 53

Building the pond ............................................................................................ 53

Excavated ponds 57

Soils .................................................................................................................. 57

Spillway and inlet requirements.................................................................... 58

Planning the pond ........................................................................................... 58

Building the pond ............................................................................................ 61

Sealing the pond 62

Compaction ..................................................................................................... 62

Clay blankets ................................................................................................... 63

Bentonite .......................................................................................................... 63

Chemical additives.......................................................................................... 64

Waterproof linings .......................................................................................... 65

Establishing vegetation 66

Protecting the pond ........................................................................................ 66

Wave action ..................................................................................................... 66

Livestock .......................................................................................................... 67

Operating and maintaining the pond 68

Pond safety 69

Before construction ........................................................................................ 69

During construction........................................................................................ 69

After completion ............................................................................................. 69

References 70

Glossary 71

Appendixes 75

Appendix A: Estimating the Volume of an Excavated Pond ..................... 75

Appendix B: Flood-Tolerant Native Trees and Shrubs .............................. 79
v

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Tables Table 1 Runoff curve numbers for urban areas 14

Table 2 Runoff curve numbers for agricultural lands 15

Table 3 Runoff curve numbers for other agricultural lands 16

Table 4 Runoff curve numbers for arid and semiarid rangelands 17

Table 5 Runoff depth, in inches 18

Table 6 Ia values for runoff curve numbers 21

Table 7 Minimum spillway design storm 27

Table 8 Permissible velocity for vegetated spillways 28

Table 9 Guide to selection of vegetal retardance 28

Table 10 Hp discharge and velocities for natural vegetated 30

spillways with 3:1 end slope (Z1

)

Table 11 Depth of flow (Hp) and slope range at retardance 34

values for various discharges, velocities, and crest lengths

Table 12 Discharge values for smooth pipe drop inlets 38

Table 13 Discharge values for corrugated metal pipe drop inlets 38

Table 14 Minimum head, h (ft), required above the invert of 41

hood inlets to provide full flow, Q (ft3

/s), for various sizes of

 smooth pipe and values of total head, H

Table 15 Minimum head, h (ft), required above the invert of 42

hood inlets to provide full flow, Q (ft3

/s), for various

 sizes of corrugated pipe and values of total head, H

Table 16 Recommended side slopes for earth dams 46

Table 17 End areas in square feet of embankment sections 48

for different side slopes and top widths

Table 18 Volume of material needed for the earthfill 51
vi

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Figures Figure 1 Typical embankment and reservoir 1

Figure 2 This pond supplies water to a stockwater trough used by 2

cattle in nearby grazing area

Figure 3 Water is pumped out of this pond for irrigation 3

Figure 4 A pond stocked with fish can provide recreation as 4

well as profit

Figure 5 A dry hydrant is needed when a pond is close enough 5

to a home or barn to furnish water for fire fighting

Figure 6 Details of a dry hydrant installation 5

Figure 7 Ponds are often used for private as well as 6

public recreation

Figure 8 Waterfowl use ponds as breeding, feeding, 7

watering places, and as resting places during migration

Figure 9 The shoreline of a well-designed pond is protected 7

from erosion by the addition of stone. Such a pond,

reflecting nearby trees, increases the value of

 the surrounding land

Figure 10 This pond, which served as a sediment basin while 8

 homes in the background were being constructed,

now adds variety and value to the community

Figure 11 A guide for estimating the approximate size of a 10

drainage area (in acres) required for each acre-foot

of storage in an embankment or excavated pond

Figure 12 Recommended minimum depth of water for ponds 11

in the United States

Figure 13 Land with permanent vegetation makes the 12

most desirable drainage area

Figure 14 A preliminary study of two alternative sites for a pond 12

 to be used for livestock water, irrigation, and recreation

Figure 15 Approximate geographic boundaries for NRCS 19

 rainfall distributions
vii

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Figure 16 Time of concentration (Tc) nomograph 20

Figure 17a Unit peak discharge (qu) for Type I storm distribution 23

Figure 17b Unit peak discharge (qu) for Type IA storm distribution 23

Figure 17c Unit peak discharge (qu) for Type II storm distribution 23

Figure 17d Unit peak discharge (qu) for Type III storm distribution 23

Figure 18 Borrow material taken from within the reservoir 25

area creates an irregular pond configuration

Figure 19 The apparent size of the pond is influenced by 26

surrounding vegetation

Figure 20 Plan, profile, and cross section of a natural spillway 29

with vegetation

Figure 21 Excavated earth spillway 33

Figure 22 Drop-inlet pipe spillway with antiseep collar 36

Figure 23 Drop-inlet pipe spillways 37

Figure 24 Dam with hooded inlet pipe spillway 39

Figure 25 Pipe inlet spillways that have trash rack and 40

 antivortex baffle

Figure 26 Water is piped through the dam’s drainpipe to 44

a stockwater trough

Figure 27 A core trench is cut on the centerline of a dam 45

Figure 28 Dam side slopes are curved and shaped to blend 46

with surounding topography

Figure 29 Finished grading techniques 47

Figure 30 A tree well preserves vegetation 53

Figure 31 Irregular clearing around the pond helps create 54

 a natural appearing edge

Figure 32 Feathering vegetation at the pond's edge makes 54

a natural transition with existing vegetation
viii

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Figure 33 The sod and topsoil in a pond construction area 56

can be stockpiled for later use

Figure 34 Geometric excavation graded to create more 58

natural configuration

Figure 35 Typical sections of an excavated pond 59

Figure 36 Correct disposal of waste material 60

Figure 37 Waste material and plantings separate the pond 61

from a major highway

Figure 38 Disking in chemical additive to seal a pond 62
ix

Agriculture Handbook 590 Ponds—Planning, Design, Construction
x

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Issued June 1982

Revised November 1997

The United States Department of Agriculture (USDA) prohibits discrimination in its programs on the basis of race, color, national origin, sex, religion,

age, disability, political beliefs, and marital or familial status. (Not all

prohibited bases apply to all programs.) Persons with disabilities who

require alternate means for communication of program information

(Braille, large print, audiotape, etc.) should contact the USDA’s TARGET

Center at (202) 720-2600 (voice and TDD).

To file a complaint, write the Secretary of Agriculture, U.S. Department of

Agriculture, Washington, DC, 20250, or call 1-800-245-6340 or (202) 720-1127

(TDD). USDA is an equal opportunity employer.
1

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Figure 1 Typical embankment and reservoir

An embankment pond (fig. 1) is made by building an

embankment or dam across a stream or watercourse

where the stream valley is depressed enough to permit

storing 5 feet or more of water. The land slope may

range from gentle to steep.

An excavated pond is made by digging a pit or dugout

in a nearly level area. Because the water capacity is

obtained almost entirely by digging, excavated ponds

are used where only a small supply of water is needed.

Some ponds are built in gently to moderately sloping

areas and the capacity is obtained both by excavating

and by building a dam.

The criteria and recommendations are for dams that

are less than 35 feet high and located where failure of

the structure will not result in loss of life; in damage to

homes, commercial or industrial buildings, main

highways, or railroads; or in interrupted use of public

utilities.

Local information is essential, and land users are

encouraged to consult with specialists experienced in

planning and building ponds.

Introduction

For many years farmers and ranchers have been

building ponds for livestock water and for irrigation.

By 1980 more than 2.1 million ponds had been built in

the United States by land users on privately owned

land. More will be needed in the future.

The demand for water has increased tremendously in

recent years, and ponds are one of the most reliable

and economical sources of water. Ponds are now

serving a variety of purposes, including water for

livestock and for irrigation, fish production, field and

orchard spraying, fire protection, energy conservation,

wildlife habitat, recreation, erosion control, and landscape improvement.

This handbook describes embankment and excavated

ponds and outlines the requirements for building each.

The information comes from the field experience and

observation of land users, engineers, conservationists,

and other specialists.

Ponds — Planning, Design,

Construction

Agriculture Handbook 590

Temporary pool Stage

P.S. inlet

crest

Top of

constructed fill

Outlet

channel

Barrel

Core trench

Frontslope

Normal pool

Top of 

settled fill

Auxiliary

spillway

Backslope

Outlet

section

Inlet

section

Cross section

(not to scale)
Ponds—Planning, Design, Construction

2

Agriculture Handbook 590

Water needs

Livestock

Clean water and ample forage are equally essential for

livestock to be finished out in a marketable condition.

If stockwater provisions in pasture and range areas are

inadequate, grazing will be concentrated near the

water and other areas will be undergrazed. This can

contribute to serious livestock losses and instability in

the livestock industry.

Watering places must also be properly distributed in

relation to the available forage. Areas of abundant

forage may be underused if water is not accessible to

livestock grazing on any part of that area (fig. 2).

Providing enough watering places in pastures encourages more uniform grazing, facilitates pasture improvement practices, retards erosion, and enables

farmers to make profitable use of soil-conserving

crops and erodible, steep areas unfit for cultivation.

An understanding of stockwater requirements helps in

planning a pond large enough to meet the needs of the

stock using the surrounding grazing area. The average

daily consumption of water by different kinds of

livestock shown here is a guide for estimating water

needs.

Kind of livestock Gallons per head per day

Beef cattle and horses 12 to 15

Dairy cows (drinking only) 15

Dairy cows (drinking and

 barn needs) 35

Hogs 4

Sheep 2

The amount of water consumed at one pond depends

on the average daily consumption per animal, number

of livestock served, and period over which they are

served.

Figure 2 This pond supplies water to a stockwater trough used by cattle in nearby grazing area
3

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Irrigation

Farm ponds are now an important source of irrigation

water (fig. 3), particularly in the East, which does not

have the organized irrigation enterprises of the West.

Before World War II irrigation was not considered

necessary in the humid East. Now many farmers in the

East are irrigating their crops.

Water requirements for irrigation are greater than

those for any other purpose discussed in this handbook. The area irrigated from a farm pond is limited by

the amount of water available throughout the growing

season. Pond capacity must be adequate to meet crop

requirements and to overcome unavoidable water

losses. For example, a 3-inch application of water on

l acre requires 81,462 gallons. Consequently, irrigation

from farm ponds generally is limited to high-value

crops on small acreages, usually less than 50 acres.

The required storage capacity of a pond used for

irrigation depends on these interrelated factors: water

requirements of the crops to be irrigated, effective

rainfall expected during the growing season, application efficiency of the irrigation method, losses due to

evaporation and seepage, and the expected inflow to

the pond. Your local NRCS conservationist can help

you estimate the required capacity of your irrigation pond.

Fish production

Many land users are finding that fish production is

profitable. A properly built and managed pond can

yield from l00 to 300 pounds of fish annually for each

acre of water surface. A good fish pond can also

provide recreation (fig. 4) and can be an added source

of income should you wish to open it to people in the

community for a fee.

Ponds that have a surface area of a quarter acre to

several acres can be managed for good fish production. Ponds of less than 2 acres are popular because

they are less difficult to manage than larger ones. A

minimum depth of 8 feet over an area of approximately

1,000 square feet is needed for best management.

Figure 3 Water is pumped out of this pond for irrigation
Ponds—Planning, Design, Construction

4

Agriculture Handbook 590

Field and orchard spraying

You may wish to provide water for applying pesticides

to your field and orchard crops. Generally, the amount

of water needed for spraying is small, but it must be

available when needed. About l00 gallons per acre for

each application is enough for most field crops. Orchards, however, may require 1,000 gallons or more

per acre for each spraying.

Provide a means of conveying water from the pond to

the spray tank. In an embankment pond, place a pipe

through the dam and a flexible hose at the downstream end to fill the spray tank by gravity. In an

excavated pond, a small pump is needed to fill the

tank.

Fire protection

A dependable water supply is needed for fighting fire.

If your pond is located close to your house, barn, or

other buildings, provide a centrifugal pump with a

power unit and a hose long enough to reach all sides

of all the buildings. Also provide for one or more dry

hydrants (figs. 5 and 6).

Although water-storage requirements for fire protection are not large, the withdrawal rate for fire fighting

is high. A satisfactory fire stream should be at least

250 gallons per minute with pressure at the nozzle of

at least 50 pounds per square inch. Fire nozzles generally are l inch to 1-1/2 inches in diameter. Use good

quality rubber-lined firehoses, 2-1/2 to 3 inches in

diameter. Preferably, the hose should be no more than

600 feet long.

A typical firehose line consists of 500 feet of 3-inch

hose and a 1-1/8 inch smooth nozzle. A centrifugal

pump operating at 63 pounds per square inch provides

a stream of 265 gallons per minute with a nozzle pressure of 50 pounds per square inch. Such a stream

running for 5 hours requires 1/4 acre-foot of water. If

you live in an area protected by a rural fire fighting

organization, provide enough storage to operate several such streams. One acre-foot of storage is enough

for four streams.

Your local dealer in pumps, engines, and similar equipment can furnish the information you need about

pump size, capacity, and engine horsepower.

Figure 4 A pond stocked with fish can provide recreation as well as profit
5

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Figure 5 A dry hydrant is needed when a pond is close enough to a home or barn to furnish water for fire fighting

Figure 6 Details of a dry hydrant installation

  



















24 in

4.5-in bronze

cap-steamer

hose

connection

Bronze nipple 4.5-in in steamer

to 4 or 6 in pipe

4- or 6-in pipe elbow

4- or 6-in pipe riser

Frost-free Ground line

depth

Cast iron elbow

Gravel covering

depth of 12 in

Well screen

Farm pond water level

Suction pipe 4- or 6-in galvanized steel or

other equally durable pipe

Not to scale

Pumping lift not over 18 ft
Ponds—Planning, Design, Construction

6

Agriculture Handbook 590

Recreation

A pond can provide many pleasant hours of swimming,

boating, and fishing. The surrounding area can be

made into an attractive place for picnics and games

(fig. 7).

Many land users realize additional income by providing water for public recreation. If the public is invited

to use a pond for a fee, the area must be large enough

to accommodate several parties engaged in whatever

recreation activities are provided.

If a pond is to be used for public recreation, supply

enough water to overcome evaporation and seepage

losses and to maintain a desirable water level. A pond

used for swimming must be free of pollution and have

an adequate depth of water near a gently sloping

shore. Minimum facilities for public use and safety are

also needed. These facilities include access roads,

parking areas, boat ramps or docks, fireplaces, picnic

tables, drinking water, and sanitary facilities.

To protect public health, most states have laws and

regulations that require water supplies to meet certain

prescribed standards if they are to be used for swimming and human consumption. Generally, water must

be tested and approved before public use is permitted.

There are also rules and regulations for building and

maintaining public sanitary facilities. The state board

of health or a similar agency administers such laws

and regulations. Contact your local health agency to

become familiar with those regulations before making

extensive plans to provide water for public recreation.

Waterfowl and other wildlife

Ponds attract many kinds of wildlife. Migratory waterfowl often use ponds as resting places in their flights

to and from the North. Ducks often use northern

ponds as breeding places, particularly where the food

supply is ample (fig. 8). Upland game birds use ponds

as watering places.

Landscape quality

Water adds variety to a landscape and further enhances its quality. Reflections in water attract the eye

and help to create a contrast or focal point in the

landscape (fig. 9). A pond visible from a home, patio,

or entrance road increases the attractiveness of the

landscape and often increases land value. Ponds in

rural, suburban, and urban areas help to conserve or

improve landscape quality.

Figure 7 Ponds are often used for private as well as public recreation
7

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Figure 8 Waterfowl use ponds as breeding, feeding, watering places, and as resting places during migration

Figure 9 The shoreline of a well-designed pond is protected from erosion by the addition of stone.

Such a pond, reflecting nearby trees, increases the value of the surrounding land
Ponds—Planning, Design, Construction

8

Agriculture Handbook 590

Regardless of its purpose, a pond’s appearance can be

improved by using appropriate principles and techniques of design. Good design includes consideration

of size, site visibility, relationship to the surrounding

landscape and use patterns, and shoreline configuration.

Your local NRCS conservationist can help you apply

the basic principles and design techniques. Consult a

landscape architect for additional information and

special designs.

Multiple purposes

You may wish to use the water in your pond for more

than one purpose; for example, to provide water for

livestock, fish production, and spraying field crops. If

so, two additional factors must be considered.

First, in estimating your water requirements you must

total the amounts needed for each purpose and be

sure that you provide a supply adequate for all the

intended uses.

Second, make sure that the purposes for which the

water is to be used are compatible. Some combinations, such as irrigation and recreation, generally are

not compatible. You would probably use most of the

water during the irrigation season, making boating and

swimming impractical.

Ponds used temporarily for grade control or as sediment basins associated with construction sites can be

converted later into permanent ponds by cleaning out

the sediment, treating the shoreline, and adding landscape measures (fig. 10). If a sediment basin is to be

cleaned and reconstructed as a water element, the

standards for dam design should be used.

Figure 10 This pond, which served as a sediment basin while homes in the background were being constructed, now adds

variety and value to the community
9

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Preliminary investigations

General considerations

Selecting a suitable site for your pond is important,

and preliminary studies are needed before final design

and construction. Analysis and selection of pond sites

should be based on landscape structure and associated ecological functions and values. Relationship of

the site to other ecological features within the landscape is critical to achieving planned objectives. If

possible, consider more than one location and study

each one to select the most ecologically appropriate,

esthetic, and practical site. Weighing both onsite and

offsite effects of constructing a pond is essential in

site selection. Refer to figure 1 and the glossary to

become familiar with the components of a pond and

associated dam.

For economy, locate the pond where the largest storage volume can be obtained with the least amount of

earthfill. A good site generally is one where a dam can

be built across a narrow section of a valley, the side

slopes are steep, and the slope of the valley floor

permits a large area to be flooded. Such sites also

minimize the area of shallow water. Avoid large areas

of shallow water because of excessive evaporation

and the growth of noxious aquatic plants.

If farm ponds are used for watering livestock, make a

pond available in or near each pasture or grazing unit.

Forcing livestock to travel long distances to water is

detrimental to both the livestock and the grazing area.

Space watering places so that livestock does not travel

more than a quarter mile to reach a pond in rough,

broken country or more than a mile in smooth, nearly

level areas. Well-spaced watering places encourage

uniform grazing and facilitate grassland management.

If pond water must be conveyed for use elsewhere,

such as for irrigation or fire protection, locate the

pond as close to the major water use as practicable.

Conveying water is expensive and, if distance is excessive, the intended use of the water may not be practical.

Ponds for fishing, boating, swimming, or other forms

of recreation must be reached easily by automobile,

especially if the general public is charged a fee to use

the pond. The success of an income-producing recreation enterprise often depends on accessibility.

Avoid pollution of pond water by selecting a location

where drainage from farmsteads, feedlots, corrals,

sewage lines, mine dumps, and similar areas does not

reach the pond. Use permanent or temporary measures, such as diversions, to redirect runoff from these

sources to an appropriate outlet until the areas can be

treated.

Do not overlook the possibility of failure of the dam

and the resulting damage from sudden release of

water. Do not locate your pond where failure of the

dam could cause loss of life; injury to persons or

livestock; damage to homes, industrial buildings,

railroads, or highways; or interrupted use of public

utilities. If the only suitable pond site presents one or

more of these hazards, hire a qualified person to

investigate other potential sites to reduce the possibility of failure from improper design or construction.

Be sure that no buried pipelines or cables cross a

proposed pond site. They could be broken or punctured by the excavating equipment, which can result

not only in damage to the utility, but also in injury to

the operator of the equipment. If a site crossed by

pipelines or cable must be used, you must notify the

utility company before starting construction and

obtain permission to excavate.

Avoid sites under powerlines. The wires may be within

reach of a fishing rod held by someone fishing from

the top of the dam.

Area adequacy of the drainage

For ponds where surface runoff is the main source of

water, the contributing drainage area must be large

enough to maintain water in the pond during droughts.

However, the drainage area should not be so large that

expensive overflow structures are needed to bypass

excess runoff during large storms.

The amount of runoff that can be expected annually

from a given watershed depends on so many interrelated factors that no set rule can be given for its determination. The physical characteristics that directly

affect the yield of water are relief, soil infiltration,

plant cover, and surface storage. Storm characteris-
Ponds—Planning, Design, Construction

10

Agriculture Handbook 590

tics, such as amount, intensity, and duration of rainfall,

also affect water yield. These characteristics vary

widely throughout the United States. Each must be

considered when evaluating the watershed area conditions for a particular pond site.

Figure 11 is a general guide for estimating the approximate size of drainage area needed for a desired waterstorage capacity. For example, a pond located in westcentral Kansas with a capacity of 5 acre-feet requires a

drainage area of at least 175 acres under normal conditions. If reliable local runoff information is available,

use it in preference to the guide.

Average physical conditions in the area are assumed to

be the normal runoff-producing characteristics for a

drainage area, such as moderate slopes, normal soil

infiltration, fair to good plant cover, and normal surface storage.

To apply the information given in figure 11, some

adjustments may be necessary to meet local conditions. Modify the values in the figure for drainage

areas having characteristics other than normal. Reduce the values by as much as 25 percent for drainage

areas having extreme runoff-producing characteristics.

Increase them by 50 percent or more for low runoffproducing characteristics.

Minimum pond depth

To ensure a permanent water supply, the water must

be deep enough to meet the intended use requirements

and to offset probable seepage and evaporation losses.

These vary in different sections of the country and

from year to year in any one section. Figure 12 shows

the recommended minimum depth of water for ponds

if seepage and evaporation losses are normal. Deeper

ponds are needed where a permanent or year-round

water supply is essential or where seepage losses

exceed 3 inches per month.

Figure 11 A guide for estimating the approximate size of a drainage area (in acres) required for each acre-foot of storage in

an embankment or excavated pond

12033

12087

25001

26083

CT

DE

FL

Note: The numbers in Mountainous areas

(green) may not apply because rainfall

in them is spotty and varies sharply. 0 200 400 600 Mi

50 35 60 8 30 8

30 60 12850

1

2

8

50

35

60

60

6030

100

140

140100

60 60 100 120

100

60

6050

3520 12

8 12

20

35

35

20 12 8

5 3 2

1.5

2 3

2

3

2

2

1.5

2

3

3

3

5

5

3 2

2

3

5 

3 

2

2 1.5 2

1.5

2 1

3

5

3

5

3

5

3

3 5

8 12 20

60

50

35

20

12

8

5

3

5

35

80

30

35

60

35 

12

80

80

60

35

100

80 120

120

120

100

80 80

8

60

30

60

120

140

100

30

60 35

100 35

2

1.5 1

1

5 3

3

3 3
11

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Drainage area protection

To maintain the required depth and capacity of a pond,

the inflow must be reasonably free of silt from an

eroding watershed. The best protection is adequate

application and maintenance of erosion control practices on the contributing drainage area. Land under

permanent cover of trees, grass, or forbs is the most

desirable drainage area (fig. 13). Cultivated areas

protected by conservation practices, such as terraces,

conservation tillage, stripcropping, or conservation

cropping systems, are the next best watershed conditions.

If an eroding or inadequately protected watershed

must be used to supply pond water, delay pond construction until conservation practices are established.

In any event, protection of the drainage area should be

started as soon as you decide to build a pond.

Figure 12 Recommended minimum depth of water for ponds in the United States

Figure 13 Land with permanent vegetation makes the

most desirable drainage area

Wet

Humid

Moist subhumid

Dry Subhumid

Semiarid

Arid

5 foot pond depth

6–7 foot pond depth

7–8 foot pond depth

8–10 foot pond depth

10–12 foot pond depth

12–14 foot pond depth

Legend

0 200 400 600 Mi
Ponds—Planning, Design, Construction

12

Agriculture Handbook 590

Landscape evaluation

Alternative pond sites should be evaluated for potential visibility and compatibility with surrounding

landscape characteristics and use patterns (fig. 14).

Identify major viewpoints (points from which the site

is viewed) and draw the important sight lines with

cross sections, where needed, to determine visibility.

If feasible, locate the pond so that the major sight line

crosses the longest dimension of water surface. The

pond should be placed so that a viewer will see the

water first before noticing the dam, pipe inlet, or

spillway. Often, minor changes in the dam alignment

and spillway location can shift these elements out of

view and reduce their prominence.

If possible, locate your pond so that some existing

trees and shrubs remain along part of the shoreline.

Vegetation adds aesthetic value by casting reflections

on the water, provides shade on summer days, and

helps blend the pond into the surrounding landscape.

A pond can often be located and designed so that an

island is created for recreation, wildlife habitat, or

visual interest.

In addition to the more typical farm and residential

sites, ponds can be located on poor quality landscapes

to rehabilitate abandoned road borrow areas, dumping

sites, abandoned rural mines, and other low production areas.

Figure 14 A preliminary study of two alternative sites for a pond to be used for livestock water, irrigation, and recreation

Pond capacity

Estimate pond capacity to be sure that enough water

is stored in the pond to satisfy the intended use requirements. A simple method follows:

• Establish the normal pond-full water elevation

and stake the waterline at this elevation.

• Measure the width of the valley at this elevation

at regular intervals and use these measurements

to compute the pond-full surface area in acres.

• Multiply the surface area by 0.4 times the maximum water depth in feet measured at the dam.

For example, a pond with a surface area of 3.2 acres

and a depth of 12.5 feet at the dam has an approximate

capacity of 16 acre-feet (0.4 x 3.2 x 12.5 = 16 acre-feet)

[1 acre-foot = 325,651 gallons].

Barn

Stockwater trough

House

Vegetable garden

Pond A

Pond B

Viewpoints

Sight lines

*

*

*

x

x

x

x

xxxxxxxx
13

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Estimating storm runoff

The amount of precipitation, whether it occurs as rain

or snow, is the potential source of water that may run

off small watersheds. The kind of soil and the type of

vegetation affect the amount of water that runs off.

Terraces and diversions, along with steepness and

shape of a watershed, affect the rate at which water

runs off.

A spillway is provided to bypass surface runoff after

the pond is filled. The tables and charts in the following sections should be used to estimate the peak

discharge rates for the spillway. They provide a quick

and reliable estimate of runoff rates and associated

volumes for a range of storm rainfall amounts, soil

groups, land use, cover conditions, and watershed

slopes.

Hydrologic groupings of soils

Soils are classified in four hydrologic groups according to infiltration and transmission rates:

A—These soils have a high infiltration rate. They are

chiefly deep, well-drained sand or gravel. The runoff

potential is low.

B—These soils have a moderate infiltration rate when

thoroughly wet. They are chiefly moderately deep,

well-drained soils of moderately fine to moderately

coarse texture.

C—These soils have a slow infiltration rate when wet.

These moderately fine to fine texture soils have a layer

that impedes downward movement of water.

D—These soils have a very slow infiltration rate. They

are chiefly clay soils that have a high swelling potential, soils with a permanent high water table, soils with

a claypan at or near the surface, and shallow soils over

nearly impervious material. The runoff potential is high.

The NRCS district conservationist or your county

extension agent can help you classify the soils for a

given pond site in one of the four hydrologic groups.

Runoff curve numbers

Tables 1 through 4 show numerical runoff ratings for a

range of soil-use-cover complexes. Because these

numbers relate to a set of curves developed from the

NRCS runoff equation, they are referred to as curve

numbers (CN) in these tables.

The watershed upstream from a farm pond often

contains areas represented by different curve numbers. A weighted curve number can be obtained based

on the percentage of area for each curve number. For

example, assume that the watershed above a pond is

mainly (three-fourths) in good pasture and a soil in

hydrologic group B. The remainder is cultivated with

conservation treatment on a soil in hydrologic group C.

A weighted curve number for the total watershed

would be:

3/4 x 61 = 46 (approximately)

1/4 x 76 = 20 (approximately)

Weighted = 66
Ponds—Planning, Design, Construction

14

Agriculture Handbook 590

Table 1 Runoff curve numbers for urban areas 1/

Cover description Average percent Curve numbers for hydrologic soil group

impervious area 2/ ABCD

Fully developed urban areas

 (vegetation established)

Open space (lawns, parks, golf courses, cemeteries, etc.) 3/

 Poor condition (grass cover < 50%) 68 79 86 89

 Fair condition (grass cover 50 to 75%) 49 69 79 84

 Good condition (grass cover > 75%) 39 61 74 80

Impervious areas:

 Paved parking lots, roofs, driveways, etc. 98 98 98 98

 (excluding right-of-way)

 Streets and roads:

 Paved; curbs and storm sewers (excluding right-of-way) 98 98 98 98

 Paved; open ditches (including right-of-way) 83 89 92 93

 Gravel (including right-of-way) 76 85 89 91

 Dirt (including right-of-way) 72 82 87 89

Western desert urban areas:

 Natural desert landscaping (pervious areas only) 4/ 63 77 85 88

 Artificial desert landscaping (impervious weed barrier,

 desert shrub with 1- to 2-inch sand or gravel mulch and 96 96 96 96

 basin borders)

Urban districts:

 Commercial and business 85 89 92 94 95

 Industrial 72 81 88 91 93

 Residential districts by average lot size:

1/8 acre or less (town houses) 65 77 85 90 92

1/4 acre 38 61 75 83 87

1/3 acre 30 57 72 81 86

1/2 acre 25 54 70 80 85

1 acre 20 51 68 79 84

2 acres 12 46 65 77 82

Developing urban areas

Newly graded areas (pervious areas only, no vegetation) 5/ 77 86 91 94

Idle lands (CN’s are determined using cover types similar to those in table 3)

1/ Average runoff condition, and Ia = 0.2S.

2/ The average percent impervious area shown was used to develop the composite CN’s. Other assumptions are as follows: impervious areas

are directly connected to the drainage system, impervious areas have a CN of 98, and pervious areas are considered equivalent to open

space in good hydrologic condition. CN’s for other combinations of conditions may be computed using figure 2-3 or 2-4 in NRCS Technical

Release 55, Urban Hydrology for Small Watersheds.

3/ CN’s shown are equivalent to those of pasture. Composite CN’s may be computed for other combinations of open space cover type.

4/ Composite CN’s for natural desert landscaping should be computed using figure 2-3 or 2-4 in Technical Release 55, based on the impervious area

percentage (CN = 98) and the pervious area CN. The pervious area CN’s are assumed equivalent to desert shrub in poor hydrologic condition.

5/ Composite CN’s to use for the design of temporary measures during grading and construction should be computed using figure 2-3 or 2-4 in

Technical Release 55, based on the degree of development (impervious area percentage) and the CN’s for the newly graded pervious areas.
15

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Table 2 Runoff curve numbers for agricultural lands 1/

 Cover description Curve numbers for hydrologic soil group

Cover type Treatment 2/ Hydrologic condition 3/ AB C D

Fallow Bare soil — 77 86 91 94

Crop residue cover (CR) Poor 76 85 90 93

Good 74 83 88 90

Row crops Straight row (SR) Poor 72 81 88 91

Good 67 78 85 89

SR + CR Poor 71 80 87 90

Good 64 75 82 85

Contoured (C) Poor 70 79 84 88

Good 65 75 82 86

C + CR Poor 69 78 83 87

Good 64 74 81 85

Contoured & terraced (C&T) Poor 66 74 80 82

Good 62 71 78 81

C&T + CR Poor 65 73 79 81

Good 61 70 77 80

Small grain SR Poor 65 76 84 88

Good 63 75 83 87

SR + CR Poor 64 75 83 86

Good 60 72 80 84

C Poor 63 74 82 85

Good 61 73 81 84

C + CR Poor 62 73 81 84

Good 60 72 80 83

C&T Poor 61 72 79 82

Good 59 70 78 81

C&T + CR Poor 60 71 78 81

Good 58 69 77 80

Closed-seeded SR Poor 66 77 85 89

 or broadcast Good 58 72 81 85

 legumes or C Poor 64 75 83 85

 rotation Good 55 69 78 83

 meadow C&T Poor 63 73 80 83

Good 51 67 76 80

1/ Average runoff condition, and Ia = 0.2S.

2/ Crop residue cover applies only if residue is on at least 5 percent of the surface throughout the year.

3/ Hydrologic condition is based on combination of factors that affect infiltration and runoff, including (a) density and canopy of vegetative

areas, (b) amount of year-round cover, (c) amount of grass or close-seeded legumes in rotations, (d) percentage of residue cover on the land

surface (good > 20%), and (e) degree of surface roughness.

 Poor: Factors impair infiltration and tend to increase runoff.

 Good: Factors encourage average and better than average infiltration and tend to decrease runoff.
Ponds—Planning, Design, Construction

16

Agriculture Handbook 590

Table 3 Runoff curve numbers for other agricultural lands 1/

 Cover description Curve numbers for hydrologic soil group

Cover type Hydrologic condition 3/ AB C D

Pasture, grassland, or range—continuous grazing 2/ Poor 68 79 86 89

Fair 49 69 79 84

Good 39 61 74 80

Meadow—continuous grass, protected from — 30 58 71 78

grazing and generally mowed for hay

Brush—brush-weed-grass mixture with brush Poor 48 67 77 83

the major element 3/ Fair 35 56 70 77

Good 30 4/ 48 65 73

Woods—grass combination (orchard Poor 57 73 82 86

or tree farm) 5/ Fair 43 65 76 82

Good 32 58 72 79

Woods 6/ Poor 45 66 77 83

Fair 36 60 73 79

Good 30 4/ 55 70 77

Farmsteads—buildings, lanes, driveways, — 59 74 82 86

 and surrounding lots.

1/ Average runoff condition, and Ia = 0.2S.

2/ Poor: <50% ground cover or heavily grazed with no mulch.

Fair: 50 to 75% ground cover and not heavily grazed.

Good: >75% ground cover and lightly or only occasionally grazed.

3/ Poor: <50% ground cover.

Fair: 50 to 75% ground cover.

Good: >75% ground cover.

4/ Actual curve number is less than 30; use CN = 30 for runoff computations.

5/ CN’s shown were computed for areas with 50% woods and 505 grass (pasture) cover. Other combinations of conditions may be computed

from the CN’s for woods and pasture.

6/ Poor: Forest litter, small trees, and brush are destroyed by heavy grazing or regular burning.

Fair: Woods are grazed but not burned, and some forest litter covers the soil.

Good: Woods are protected from grazing, and litter and brush adequately cover the soil.
17

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Table 4 Runoff curve numbers for arid and semiarid rangelands 1/

 Cover description Curve numbers for hydrologic soil group

Cover type Hydrologic condition 2/ A 3/ B CD

Herbaceous—mixture of grass, forbs, and Poor — 80 87 93

 low-growing brush, with brush the minor element Fair — 71 81 89

Good — 62 74 85

Oak-aspen—mountain brush mixture of oak brush, Poor — 66 74 79

 aspen, mountain mahogany, bitter brush, maple, Fair — 48 57 63

 and other brush. Good — 30 41 48

Pinyon-juniper—pinyon, juniper, or both Poor — 75 85 89

 grass understory Fair — 58 73 80

Good — 41 61 71

Sagebrush with grass understory Poor — 67 80 85

Fair — 51 63 70

Good — 35 47 55

Desert shrub—major plants include saltbush, Poor 63 77 85 88

 greasewood, creosotebush, blackbrush, bursage, Fair 55 72 81 86

palo verde, mesquite, and cactus Good 49 68 79 84

1/ Average runoff condition, and Ia = 0.2S. For range in humid regions, use table 3.

2/ Poor: <30% ground cover (litter, grass, and brush overstory).

Fair: 30 to 70% ground cover.

Good: >70% ground cover.

3/ Curve numbers for group A have been developed only for desert shrub.
Ponds—Planning, Design, Construction

18

Agriculture Handbook 590

Volume of storm runoff

Often knowing how much water runs off from a big

storm as well as the rate at which it flows is good. The

volume is needed to compute needed storage as well

as the peak discharge rate.

The figures in table 5 are the depth (in inches) at

which the storm runoff, if spread evenly, would cover

the entire watershed. For example, the volume of

runoff from a 3-inch rainfall on a 100-acre watershed

with the weighted curve number of 66 would be:

0.55 inch (interpolated between 0.51 and 0.72 inches)

100 acres x 0.55 inch = 55 acre-inches

55 acre-inches ÷12 = 4.55 acre-feet

55 acre-inches x 27,152 gallons per acre-inch = 1.5

million gallons (approximately)

Table 5 Runoff depth, in inches

Rainfall Curve number

(inches) 60 65 70 75 80 85 90

1.0 0 0 0 0.03 0.08 0.17 0.32

1.2 0 0 0.03 0.07 0.15 0.28 0.46

1.4 0 0.02 0.06 0.13 0.24 0.39 0.61

1.6 0.01 0.05 0.11 0.20 0.34 0.52 0.76

1.8 0.03 0.09 0.17 0.29 0.44 0.65 0.93

2.0 0.06 0.14 0.24 0.38 0.56 0.80 1.09

2.5 0.17 0.30 0.46 0.65 0.89 1.18 1.53

3.0 0.33 0.51 0.72 0.96 1.25 1.59 1.98

4.0 0.76 1.03 1.33 1.67 2.04 2.46 2.92

5.0 1.30 1.65 2.04 2.45 2.89 3.37 3.88

6.0 1.92 2.35 2.87 3.28 3.78 4.31 4.85

7.0 2.60 3.10 3.62 4.15 4.69 5.26 5.82

8.0 3.33 3.90 4.47 5.04 5.62 6.22 6.81

9.0 4.10 4.72 5.34 5.95 6.57 7.19 7.79

10.0 4.90 5.57 6.23 6.88 7.52 8.16 8.78

11.0 5.72 6.44 7.13 7.82 8.48 9.14 9.77

12.0 6.56 7.32 8.05 8.76 9.45 10.12 10.76
19

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Rainfall amounts and expected

frequency

Maps in U.S. Weather Bureau Technical Paper 40

(USWP-TP-40), Rainfall Frequency Atlas of the United

States, show the amount of rainfall expected in a 24-

hour period. These maps have also been reprinted in

Hydrology for Small Urban Watershed, Technical

Release 55. Contact your local NRCS field office for

rainfall amounts on maps.

Designing an ordinary pond spillway to accommodate

the peak rate of runoff from the most intense rainstorm ever known or anticipated is not practical. The

spillway for an ordinary farm pond generally is designed to pass the runoff from a 25-year frequency

storm. This means a storm with only a 4 percent

chance of occurring in any year or the size beyond

which larger storms would not occur more often than

an average of once in 25 years. Designing for a 50-year

storm frequency is recommended for spillways for

larger dams. A 10-year storm frequency may be adequate for sizing the spillway in small ponds.

Rainfall distribution

The highest peak discharges from small watersheds

are usually caused by intense, brief rainfalls that may

occur as part of a longer duration storm. Different

rainfall distributions with respect to time have been

developed for four geographic areas of the United

States. For each of these areas, a set of synthetic

rainfall distributions having nested rainfall intensities

were developed. These distributions maximize the

rainfall intensities by incorporating selected storm

duration intensities within those needed for longer

durations at the same probability level.

In figure 15, type I and IA represent the Pacific maritime climate with wet winters and dry summers. Type

III represents Gulf of Mexico and Atlantic coastal

areas where tropical storms bring large rainfall

amounts. Type II represents the rest of the country.

Figure 15 Approximate geographic boundaries for NRCS rainfall distributions

Type I

Type IA

Type II

Type III

Legend

0 200 400 600 Mi
Ponds—Planning, Design, Construction

20

Agriculture Handbook 590

Peak discharge rate

The slope of the land above the pond affects the peak

discharge rate significantly. The time of concentration

along with the runoff curve number, storm rainfall,

and rainfall distribution are used to estimate the peak

discharge rate. This rate is used to design the auxiliary

spillway width and depth of flow.

Time of concentration

Time of concentration (Tc) is the time it takes for

runoff to travel from the hydraulically most distant

point of the watershed to the outlet. Tc influences the

peak discharge and is a measure of how fast the water

runs off the land. For the same size watershed, the

shorter the Tc, the larger the peak discharge. This

means that the peak discharge has an inverse relationship with Tc. Tc can be estimated for small rural watersheds using equation 1. Figure 16 is a nomograph for

solving this equation.

T

l

CN

Y c =

 ( ) −















0 8

0 7

0 5

1000 9

1140

.

.

.

[Eq. 1]

where:

Tc = time of concentration, hr

l = flow length, ft

CN = runoff curve number

Y = average watershed slope, %

Figure 16 Time of concentration (Tc) nomograph

0.1 .3 .5

100 1,000 10,000

Flow length (l), feet

Time of concentration (Tc), hrs

1.0 2 3 4 5 6 8 10

Watershed slope T=

0.5

1

4

8

16

32

64

80

70

60

50

2

40

95

90
21

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Average watershed slope

The average watershed slope (Y) is the slope of the

land and not the watercourse. It can be determined

from soil survey data or topographic maps. Hillside

slopes can be measured with a hand level, lock level,

or clinometer in the direction of overland flow. Average watershed slope is an average of individual land

slope measurements. The average watershed slope can

be determined using equation 2:

Y CI

A = 100 [Eq. 2]

where:

Y = average slope, %

C = total contour length, ft

I = contour interval, ft

A = drainage area, ft2

Flow length

Flow length (l) is the longest flow path in the watershed from the watershed divide to the outlet. It is the

total path water travels overland and in small channels

on the way to the outlet. The flow length can be determined using a map wheel, or it can be marked along

the edge of a paper and converted to feet.

Ia /P ratio

The watershed CN is used to determine the initial

abstraction (Ia) from table 6. Ia/P ratio is a parameter

that indicates how much of the total rainfall is needed

to satisfy the initial abstraction. The larger the Ia/P ratio,

the lower the unit peak discharge (qu) for a given Tc.

Table 6 Ia values for runoff curve numbers

Curve Ia Curve Ia

number (in) number (in)

40 3.000 70 0.857

41 2.878 71 0.817

42 2.762 72 0.778

43 2.651 73 0.740

44 2.545 74 0.703

45 2.444 75 0.667

46 2.348 76 0.632

47 2.255 77 0.597

48 2.167 78 0.564

49 2.082 79 0.532

50 2.000 80 0.500

51 1.922 81 0.469

52 1.846 82 0.439

53 1.774 83 0.410

54 1.704 84 0.381

55 1.636 85 0.353

56 1.571 86 0.326

57 1.509 87 0.299

58 1.448 88 0.273

59 1.390 89 0.247

60 1.333 90 0.222

61 1.279 91 0.198

62 1.226 92 0.174

63 1.175 93 0.151

64 1.125 94 0.128

65 1.077 95 0.105

66 1.030 96 0.083

67 0.985 97 0.062

68 0.941 98 0.041

69 0.899
Ponds—Planning, Design, Construction

22

Agriculture Handbook 590

Estimating peak discharge rates

The unit peak discharge (qu) is obtained from figure 17

depending on the rainfall type. Figure 15 shows the

approximate geographic boundaries for the four

rainfall distributions. Tc and Ia/P values are needed to

obtain a value for qu from the exhibit. The peak discharge (qp in ft3/s) is computed as the product of the

unit peak discharge (qu in ft3/s/ac-in), the drainage

area (A in acres), and the runoff (Q in inches).

q q AQ p u = ×× [Eq. 3]

Example 1 Estimating peak discharge rates

Known:

Drainage area = 50 acres

Cole County, Missouri

Flow Path ‘l’ = 1,600 feet

Watershed Slope ‘Y’ = 4 percent

25-year, 24-hour rainfall = 6 inches

Type II rainfall distribution

Runoff Curve Number = 66

(from example in runoff curve number section)

Solution:

Find Tc

Enter figure 16, Tc = 0.60 hours

Find Ia /P

Enter table 6, use CN = 66, Ia = 1.030

Ia /P = 1.030/6.0 inches = 0.172

Find runoff

Enter table 5, at rainfall = 6.0 inches

 and runoff curve number = 66,

Read runoff = 2.44 inches. (Note: It was neces-

 sary to interpolate between RCN 65 and 70.)

Find the peak discharge for spillway design.

Enter figure 17(c):

qu = 0.7

qp = qu x A x Q

qp = 0.7 x 50 x 2.44 = 85 ft3/s
23

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Figure 17a Unit peak discharge (qu) for Type I storm

distribution

Figure 17b Unit peak discharge (qu) for Type IA storm

distribution

Figure 17c Unit peak discharge (qu) for Type II storm

distribution

Figure 17d Unit peak discharge (qu) for Type III storm

distribution

1.0

Time of concentration (Tc), hours

Unit peak discharge (qu) ft3/s ac-in 

.8

.7

.6

.5

.4

.3

.2

.1

.08

.07

.06

.1 .2 .3 .4 .5 .6 .8 10 5

Ia/P=.1

.2

.30

.35

.40

.45

.50

.25

1.6

.7

.6

.5

1.0

.4

.3

.2

.1

.07

.1 1.0 10

Time of concentration (Tc), hours

Unit peak discharge (qu) ft3/s ac-in 

Ia/P=.1

.3

.35

.40

.45

.50

1.6

.7

.6

.5

1.0

.4

.3

.2

.1

.07

.1 1.0 10

Time of concentration (Tc), hours

Unit peak discharge (qu) ft3/s ac-in 

Ia/P=.1

.3

.35

.40

.45

.50

.3

.2

.1

.09

.08

.07

.06

.05

.1 1 10

Time of concentration (Tc), hours

Unit peak discharge (qu) ft3/s ac-in 

Ia/P=.1

.2

.25

.30

.50
Ponds—Planning, Design, Construction

24

Agriculture Handbook 590

Embankment ponds

Detailed soils investigation

Soils in the ponded area—Suitability of a pond site

depends on the ability of the soils in the reservoir area

to hold water. The soil should contain a layer of material that is impervious and thick enough to prevent

excessive seepage. Clays and silty clays are excellent

for this purpose; sandy and gravelly clays are usually

satisfactory. Generally, soils with at least 20 percent

passing the No. 200 sieve, a Plasticity Index of more

than 10 percent, and an undisturbed thickness of at

least 3 feet do not have excessive seepage when the

water depth is less than 10 feet. Coarse-textured sands

and sand-gravel mixtures are highly pervious and

therefore usually unsuitable. The absence of a layer of

impervious material over part of the ponded area does

not necessarily mean that you must abandon the

proposed site. You can treat these parts of the area by

one of several methods described later in this handbook. Any of these methods can be expensive.

Some limestone areas are especially hazardous as

pond sites. Crevices, sinks, or channels that are not

visible from the surface may be in the limestone below

the soil mantle. They may empty the pond in a short

time. In addition, many soils in these areas are granular. Because the granules do not break down readily in

water, the soils remain highly permeable. All the

factors that may make a limestone site undesirable are

not easily recognized without extensive investigations

and laboratory tests. The best clue to the suitability of

a site in one of these areas is the degree of success

others have had with farm ponds in the immediate

vicinity.

Unless you know that the soils are sufficiently impervious and that leakage will not be a problem, you should

make soil borings at intervals over the area to be

covered with water. Three or four borings per acre

may be enough if the soils are uniform. More may be

required if there are significant differences.

Foundation conditions—The foundation under a

dam must ensure stable support for the structure and

provide the necessary resistance to the passage of

water.

Site surveys

Once you determine the probable location of the pond,

conduct a site survey to plan and design the dam,

spillways, and other features. Those unfamiliar with

the use of surveying instruments should employ a

licensed surveyor or other qualified professional.

Pond surveys generally consist of a profile of the

centerline of the dam, a profile of the centerline of the

earth spillway, and enough measurements to estimate

pond capacity. A simple method of estimating pond

capacity is described on page 12. For larger and more

complex ponds, particularly those used for water

supply or irrigation, you may need a complete topographic survey of the entire pond site.

Run a line of profile level surveys along the centerline

of the proposed dam and up both sides of the valley

well above the expected elevation of the top of the

dam and well beyond the probable location of the

auxiliary spillway. The profile should show the surface

elevation at all significant changes in slope and at

intervals of no more than 100 feet. This line of levels

establishes the height of the dam and the location and

elevation of the earth spillway and the principal spillway. It is also used to compute the volume of earthfill

needed to build the dam.

Run a similar line of profile levels along the centerline

of the auxiliary spillway. Start from a point on the

upstream end that is well below the selected normal

water surface elevation and continue to a point on the

downstream end where water can be safely discharged

without damage to the dam. This line serves as a basis

for determining the slope and dimensions of the spillway.

All surveys made at a pond site should be tied to a

reference called a bench mark. This may be a large

spike driven into a tree, an iron rod driven flush with

the ground, a point on the concrete headwall of a

culvert, or any object that will remain undisturbed

during and after construction of the dam.
25

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Soil borings help to investigate thoroughly the foundation conditions under the proposed dam site. The

depth of the holes should be at least 1-1/2 times the

height of the proposed dam. Ensure there are not any

steep dropoffs in the rock surface of the foundation

under the dam. Steep dropoffs in the rock surface can

result in cracking of the embankment. Study the

natural banks (abutments) at the ends of the dam as

well as the supporting materials under the dam. If the

dam is to be placed on rock, the rock must be examined for thickness and for fissures and seams through

which water might pass.

Coarse-textured materials, such as gravel, sand, and

gravel-sand mixtures, provide good support for a dam,

but are highly pervious and do not hold water. Such

materials can be used only if they are sealed to prevent

seepage under the dam. You can install a cutoff core

trench of impervious material under the dam or blanket the upstream face of the dam and the pond area

with a leak-resistant material.

Fine-textured materials, such as silts and clays, are

relatively impervious, but have a low degree of stability. They are not good foundation materials, but generally are satisfactory for the size of dams discussed in

this handbook. Flattening the side slopes of some

dams may be necessary to reduce the unit load on the

foundation. Remove peat, muck, and any soil that has

a high organic-matter content from the foundation.

Good foundation materials, those that provide both

stability and imperviousness, are a mixture of coarseand fine-textured soils. Some examples are gravelsand-clay mixtures, gravel-sand-silt mixtures, sandclay mixtures, and sand-silt mixtures.

Less desirable but still acceptable foundation materials for ordinary pond dams are gravelly clays, sandy

clays, silty clays, silty and clayey fine sands, and

clayey silts that have slight plasticity.

Fill material—The availability of suitable material for

building a dam is a determining factor in selecting a

pond site. Enough suitable material should be located

close to the site so that placement costs are not excessive. If fill material can be taken from the reservoir

area, the surrounding landscape will be left undisturbed and borrow areas will not be visible after the

pond has been filled (fig. 18).

Materials selected must have enough strength for the

dam to remain stable and be tight enough, when properly compacted, to prevent excessive or harmful

percolation of water through the dam. Soils described

as acceptable for foundation material generally are

acceptable for fill material. The exceptions are organic

silts and clays.

The best material for an earthfill contains particles

ranging from small gravel or coarse sand to fine sand

and clay in the desired proportions. This material

should contain about 20 percent, by weight, clay

particles. Though satisfactory earthfills can be built

from soils that vary from the ideal, the greater the

variance, the more precautions needed.

Soils containing a high percentage of gravel or coarse

sand are pervious and can allow rapid seepage

through the dam. When using these soils, place a core

of clay material in the center of the fill and flatten the

side slopes to keep the line of seepage from emerging

on the downstream slope.

Fill material that has a high clay content swells when

wet and shrinks when dry. The shrinkage may open

dangerous cracks. If these soils are dispersive, they

represent a serious hazard to the safety of the embankment and should be avoided. Dispersive soils can be

identified by how easily they go into suspension in

water, by the presence of a gelatinous cloud around a

clod of soil in distilled water, and by the indefinite

Figure 18 Borrow material taken from within the

reservoir area creates an irregular pond

configuration


Ponds—Planning, Design, Construction

26

Agriculture Handbook 590

length of time they stay in suspension in still water.

High sodium soils identified in the soil survey for the

planned area of the embankment also indicate dispersive soils. If any of these indicators are found at the

proposed site, an engineer should be hired to provide

the necessary guidance for sampling, testing, and

using these soils for fill. For soils consisting mostly of

silt, such as the loess areas of western Iowa and along

the Mississippi River in Arkansas, Mississippi, and

Tennessee, the right degree of moisture must be maintained during construction for thorough compaction.

To estimate the proportion of sand, silt, and clay in a

sample of fill material, first obtain a large bottle with

straight sides. Take a representative sample of the fill

material and remove any gravel by passing the material through a 1/4-inch sieve or screen. Fill the bottle to

about one-third with the sample material and finish

filling with water. Shake the bottle vigorously for

several minutes and then allow the soil material to

settle for about 24 hours. The coarse material (sand)

settles to the bottom first, and finer material (clay)

settles last. Estimate the proportion of sand, silt, and

clay by measuring the thickness of the different layers

with a ruler.

Landscape planning—The pond should be located

and designed to blend with the existing landform,

vegetation, water, and structures with minimum disturbance. Landforms can often form the impoundment

with minimum excavation. Openings in the vegetation

can be used to avoid costly clearing and grubbing.

Existing structures, such as stone walls and trails, can

be retained to control pedestrian and vehicular traffic

and minimize disruption of existing use. In the area

where land and water meet, vegetation and landform

can provide interesting reflections on the water’s

surface, guide attention to or from the water, frame

the water to emphasize it, and direct passage around

the pond.

A pond’s apparent size is not always the same as its

actual size. For example, the more sky reflected on the

water surface, the larger a pond appears. A pond

surrounded by trees will appear smaller than a pond

the same size without trees or with some shoreline

trees (fig. 19). The shape of a pond should complement its surroundings. Irregular shapes with smooth,

flowing shorelines generally are more compatible with

the patterns and functions found in most landscapes.

Peninsulas, inlets, or islands can be constructed to

create diversity in the water’s edge.

Spillway requirements

A pipe spillway often is used as well as an earth auxiliary spillway to control runoff from the watershed.

The principal spillway is designed to reduce the frequency of operation of the auxiliary spillway. Commonly the principal spillway may be a hooded or

canopy inlet with a straight pipe or may be a drop inlet

(vertical section) that has a pipe barrel through the

dam. The pipe shall be capable of withstanding external loading with yielding, buckling, or cracking. The

pipe joints and all appurtenances need to be watertight. Pipe materials may be smooth metal, corrugated

metal, or plastic. Design limitations exist with all

materials.

A small principal spillway pipe, formerly called a

trickle tube, only handles a small amount of flow. Its

purpose is to aid in keeping the auxiliary spillway dry

during the passage of small storm events.

Hooded or canopy inlets are common. A disadvantage

of this type inlet is the larger amount of stage (head

over the inlet crest) needed to make the pipe flow at

full capacity. Conversely, a drop inlet spillway requires

less stage because the size of the inlet may be enlarged

to make the barrel flow full.

Figure 19 The apparent size of the pond is influenced

by surrounding vegetation
27

Agriculture Handbook 590 Ponds—Planning, Design, Construction

The principal spillway normally is sized to control the

runoff from a storm ranging from a 1-year to a 10-year

frequency event. This depends on the size of the drainage area. For pond sites where the drainage area is

small (less than 20 acres) and the condition of the

vegetated spillway is good, no principal spillway is

required except where the pond is spring fed or there

are other sources of steady baseflow. In this case, a

trickle tube shall be installed.

Earth spillways have limitations. Use them only where

the soils and topography allow the peak flow to discharge safely at a point well downstream and at a

velocity that does not cause appreciable erosion either

within the spillway or beyond its outlet.

Soil borings generally are required for auxiliary spillways if a natural site with good plant cover is available. If spillway excavation is required, the investigations should be thorough enough to determine

whether the soils can withstand reasonable velocities

without serious erosion. Avoid loose sands and other

highly erodible soils.

No matter how well a dam has been built, it will probably be destroyed during the first severe storm if the

capacity of the spillway is inadequate. The function of

an auxiliary spillway is to pass excess storm runoff

around the dam so that water in the pond does not rise

high enough to damage the dam by overtopping. The

spillways must also convey the water safely to the

outlet channel below without damaging the downstream slope of the dam. The proper functioning of a

pond depends on a correctly designed and installed

spillway system.

Auxiliary spillways should have the minimum capacity

to discharge the peak flow expected from a storm of

the frequency and duration shown in table 7 less any

reduction creditable to conduit discharge and detention storage. After the spillway capacity requirements

are calculated, the permissible velocity must be determined. Table 8 shows the recommended allowable

velocity for various cover, degree of erosion resistance, and slope of the channel. Table 9 gives the

retardance factors for the expected height of the

vegetation.

Both natural and excavated auxiliary spillways are

used. A natural spillway does not require excavation to

provide enough capacity to conduct the pond outflow

to a safe point of release (fig. 20). The requirements

discussed later for excavated spillways do not apply to

natural spillways, but the capacity must be adequate.

With the required discharge capacity (Q), the end

slope of the embankment (Z1), and the slope of the

natural ground (Z2) known, the maximum depth of

water above the level portion (Hp) can be obtained

from table 10. The depth is added to the elevation of

the spillway crest to determine the maximum elevation to which water will rise in the reservoir.

Table 7 Minimum spillway design storm

Drainage Effective Storage Minimum design storm

area height Frequency Minimum

of dam 1/ duration

(acre) (ft) (acre-ft) (yr) (hr)

20 or less 20 or less Less than 50 10 24

20 or less More than 20 Less than 50 25 24

More than 20 20 or less Less than 50 25 24

All others 50 24

1/ The effective height of the dam is the difference in elevation between the auxiliary spillway crest and the lowest point in the cross section

taken along the centerline of the dam.
Ponds—Planning, Design, Construction

28

Agriculture Handbook 590

Table 8 Permissible velocity for vegetated spillways 1/

Vegetation - - - - - - - - - - - - - - - - - - - - - - - -Permissible velocity 2/ - - - - - - - - - - - - - - - - - - - - - -

Erosion-resistant soils 3/ Easily eroded soils 4/

- - - - - - - - - - - - - - - - - - - - - - - Slope of exit channel (%) - - - - - - - - - - - - - - - - - - - -

0-5 5-10 0-5 5-10

(ft/s) (ft/s) (ft/s) (ft/s)

Bermudagrass 8765

Bahiagrass 8765

Buffalograss 7654

Kentucky bluegrass 7654

Smooth brome 7654

Tall fescue 7654

Reed canarygrass 7654

Sod-forming grass-legume mixtures 5443

Lespedeza sericea 3.5 3.5 2.5 2.5

Weeping lovegrass 3.5 3.5 2.5 2.5

Yellow bluestem 3.5 3.5 2.5 2.5

Native grass mixtures 3.5 3.5 2.5 2.5

1/ SCS TP-61

2/ Increase values 10 percent when the anticipated average use of the spillway is not more frequent than once in 5 years, or 25 percent when

the anticipated average use is not more frequent than once in 10 years.

3/ Those with a higher clay content and higher plasticity. Typical soil textures are silty clay, sandy clay, and clay.

4/ Those with a high content of fine sand or silt and lower plasticity, or nonplastic. Typical soil textures are fine sand, silt, sandy loam, and silty

loam.

Table 9 Guide to selection of vegetal retardance

Stand Average height Degree of

of vegetation (in) retardance

Good Higher than 30 A

11 to 24 B

6 to 10 C

2 to 6 D

Less than 2 E

Fair Higher than 30 B

11 to 24 C

6 to 10 D

2 to 6 D

Less than 2 E
29

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Figure 20 Plan, profile, and cross section of a natural spillway with vegetation

















  









 



 Maximum water elevation

End slope protected with rock riprap

Natural ground

Top of dam

Z Hp 2

Z1

Typical control section

Profile Plan view

L

Wing dike

used to protect

embankment

Toe of dam

Centerline of dam

Embankment to be

perpendicular to slope

   

Spillway crest

L

Hp

Level part
Ponds—Planning, Design, Construction

30

Agriculture Handbook 590

Table 10 Hp discharge and velocities for natural vegetated spillways with 3:1 end slope (Z1)

Natural Retardance

ground - - - - - A - - - - - - - - - - B - - - - - - - - - - C - - - - - - - - - - D - - - - - - - - - - E - - - - - - - - - Slope - - - -

slope Z2 Hp Q V QV QV QV QV Min. Max.

(%) (ft) (ft3/s) (ft/s) (ft3/s) (ft/s) (ft3/s) (ft/s) (ft3/s) (ft/s) (ft3/s) (ft/s) (%) (%)

0.5 1.0 19 0.3 28 0.5 47 1.3 68 1.8 130 2.8 0.5 3

1.1 21 .3 35 .5 76 1.5 108 2.1 154 3.0

1.2 29 .4 39 .6 97 1.6 122 2.3 204 3.2

1.3 36 .4 53 .6 125 2.0 189 2.5 250 3.4

1.5 61 .4 87 1.1 210 2.2 291 2.9 393 3.8

1.8 81 .5 187 1.8 384 2.9 454 3.5 651 4.5

2.0 110 .5 286 2.1 524 3.3 749 3.8 860 4.8

1 1.0 10 0.4 16 0.5 31 2.0 45 2.6 64 3.4 1 3

1.1 13 .4 18 .6 50 2.3 63 2.8 90 3.7

1.2 15 .5 21 .8 62 2.5 78 3.1 99 4.0

1.3 22 .6 39 1.0 86 2.7 144 3.4 139 4.3

1.5 40 .7 75 1.8 133 3.1 186 4.0 218 5.1

1.8 56 .8 126 2.3 280 3.8 296 4.5

2.0 98 1.1 184 2.8 328 4.3 389 5.0

2.5 171 2.5 472 4.1 680 5.4

2 1.0 6 0.5 9 0.8 18 2.5 27 3.3 36 4.2 1 3

1.1 7 .7 14 1.0 29 2.8 39 3.6 50 4.5

1.2 9 .8 19 1.1 40 3.1 51 3.9 64 4.9

1.3 13 .9 26 1.6 50 3.4 70 4.3 85 5.3

1.5 21 1.0 39 2.0 70 3.9 109 5.1 127 6.3

1.8 26 1.1 74 2.5 126 4.8 194 5.9

2.0 52 1.3 111 3.2 190 5.4 229 6.4

2.5 88 2.8 238 5.2 339 6.8

3 1.0 4 0.7 7 0.8 15 2.8 21 3.7 28 4.8 1 3

1.1 5 .8 10 .9 24 3.2 31 4.0 38 5.2

1.2 7 .9 14 1.1 33 3.6 41 4.4 49 5.6

1.3 10 1.0 20 1.5 42 3.8 57 4.8 67 6.1

1.5 16 1.2 34 2.8 62 4.4 89 5.7 104 7.2

1.8 23 1.3 57 3.0 112 5.5 143 6.7

2.0 39 1.5 81 3.7 163 6.2 194 7.2

2.5 85 3.1 212 6.0 300 7.8

4 1.2 6 1.0 11 1.4 25 3.9 31 4.8 38 6.1 1 4

1.5 15 1.3 29 3.1 49 4.8 69 5.5 81 7.9

1.8 20 1.4 47 4.1 98 6.1 116 7.3

2.0 30 1.6 65 4.7 139 6.7 161 7.8

2.5 72 3.3 167 6.6 238 8.5

5 1.5 13 1.4 23 3.3 38 5.2 55 6.7 63 8.4 1 5

1.8 17 1.5 37 4.4 76 6.5 95 7.9

2.0 23 1.7 48 5.1 112 7.1 130 8.1

2.5 64 3.7 149 7.1 191 9.2
31

Agriculture Handbook 590 Ponds—Planning, Design, Construction

The following example shows how to use table 10:

Given:

Vegetation: good stand of bermudagrass

Height: 6 to 10 inches

Slope of natural ground: 1.0 percent

Solution:

From table 9, determine a retardance of C.

From table 10, under natural ground slope

1 percent and retardance C column,

find Q = 88

ft3/s at Hp = 1.3 ft, and

V = 2.7 ft/s.

If the freeboard is 1.0 foot, the top of the dam should

be constructed 2.3 feet higher than the spillway crest.

The velocity is well below the maximum permissible

velocity of 6 feet per second given in table 8. Hp can be

determined by interpolation when necessary. For a Q

greater than that listed in table 10, the spillway should

be excavated according to the information in the next

section, Excavated auxiliary spillways.

Excavated auxiliary spillways—Excavated spillways consist of the three elements shown in figure 21.

The flow enters the spillway through the inlet channel.

The maximum depth of flow (Hp) located upstream

from the level part is controlled by the inlet channel,

level part, and exit channel.

Excavation of the inlet channel or the exit channel, or

both, can be omitted where the natural slopes meet

the minimum slope requirements. The direction of

slope of the exit channel must be such that discharge

does not flow against any part of the dam. Wing dikes,

sometimes called kicker levees or training levees, can

be used to direct the outflow to a safe point of release

downstream.

The spillway should be excavated into the earth for its

full depth. If this is not practical, the end of the dam

and any earthfill constructed to confine the flow

should be protected by vegetation or riprap. The

entrance to the inlet channel should be widened so it

is at least 50 percent greater than the bottom width of

the level part. The inlet channel should be reasonably

short and should be planned with smooth, easy curves

for alignment. It should have a slope toward the reservoir of not less than 2.0 percent to ensure drainage and

low water loss at the inlet.

With the required discharge capacity, the degree of

retardance, permissible velocity, and the natural slope

of the exit channel known, the bottom width of the

level and exit sections and the depth of the flow (Hp)

can be computed using the figures in table 11. This

table shows discharge per foot of width. The natural

slope of the exit channel should be altered as little as

possible.

The selection of the degree of retardance for a given

auxiliary spillway depends mainly on the height and

density of the cover chosen (table 9). Generally, the

retardance for uncut grass or vegetation is the one to

use for capacity determination. Because protection

and retardance are lower during establishment and

after mowing, to use a lower degree of retardance

when designing for stability may be advisable.

The following examples show the use of the information in table 11:

Example 1 where only one retardance is used for

capacity and stability:

Given:

Q = 87 ft3/s (total design capacity)

So = 4 percent (slope of exit channel determined

from profile, or to be excavated)

L = 50 ft

Earth spillway is to be excavated in an erosion-resistant soil and planted with a sod-forming grass-legume

mixture. After establishment, a good stand averaging

from 6 to 10 inches in height is expected.

Required:

Permissible velocity (V)

Width of spillway (b)

Depth of water in the reservoir above the crest (Hp).

Solution:

From table 8 for sod-forming grass-legume

mixtures, read permissible velocity V = 5 ft/s.

From table 9 for average height of vegetation of 6 to

10 inches, determine retardance C.
Ponds—Planning, Design, Construction

32

Agriculture Handbook 590

For retardance C, enter table 11 from left at 

maximum velocity V = 5 ft/s. A 4 percent slope is in

the slope range of 1–6 with Q of 3 ft3/s/ft.

Hp for L of 50 ft = 1.4 ft.

If the freeboard is 1 foot, the spillway should be constructed 29 feet wide and 2.4 feet deep.

For retardance C, enter table 11 from left at 

maximum velocity V = 5 ft/s. A 4 percent slope is in

the slope range of 1–6 with Q of 3 ft3/s/ft.

Hp for L of 50 ft = 1.4 ft.

If the freeboard is 1 foot, the spillway should be constructed 29 feet wide and 2.4 feet deep.

Example 2 where one retardance is used for stability

and another is used for capacity:

Given:

So = 4 percent (slope of exit channel determined

from profile or to be excavated)

L = 50 ft

Earth spillway is to be excavated in a highly erodible

soil and planted with bahiagrass. After establishment a

good stand of 11 to 24 inches is expected.

Required:

Permissible velocity (V)

Width of spillway (b)

Depth of water in reservoir above the crest (Hp).

Solution:

From table 8 determine permissible velocity for

bahiagrass in a highly erodible soil that has 8 percent slope V = 5 ft/s.

From table 9, select retardants to be used for stability during an establishment period that has a good

stand of vegetation of 2 to 6 inches (retardance D).

Select retardance to be used for capacity for good

stand of vegetation that has a length of

11 to 24 inches (retardance B).

From table 11, enter from left at maximum velocity

V = 5 ft/s. A slope of 6 percent is in the range

for Q = 2 ft3/s/ft.

Then

From table 11, enter q = 2 ft3/s/ft under retardance

B and find Hp for L of 25 ft = 1.4 ft.

If the freeboard is 1 foot, the spillway should be

constructed 50 feet wide and 2.4 feet deep.

Protection against erosion—Protect auxiliary

spillways against erosion by establishing good plant

cover if the soil and climate permit. As soon after

construction as practicable, prepare the auxiliary

spillway area for seeding or sodding by applying

fertilizer or manure. Sow adapted perennial grasses

and protect the seedlings to establish a good stand.

Mulching is necessary on the slopes. Irrigation is often

needed to ensure good germination and growth, particularly if seeding must be done during dry periods. If

the added cost is justified, sprigging or sodding suitable

grasses, such as bermudagrass, gives quick protection.
33

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Figure 21 Excavated earth spillway

  





Exit channel CL CL

CL

CL

Exit channel

Embankment

Inlet channel

Wing dike

Level portion

(Note: Use care to keep all

machinery and traffic out of 

the spillway discharge area 

to protect sod.)

(Note: Neither the location nor

the alignment of the level

portion has to coincide with the

center line of the dam.)

Embankment

Berm

Excavated earth spillway Optional with sod

or riprap on wing dike

Plan view of earth spillways

Profile along centerline

Cross section of level portion

Level portion

Inlet

channel







 

Exit channel

Level portion

Water surface

Inlet channel

Se

Hp

So

Definition of terms:

Hp = depth of water in reservoir above crest

L = length of level portion min. 25 ft

b = bottom width of spillway

So = slope for exit channel

Se = slope of inlet channel

L

b

1

3
Ponds—Planning, Design, Construction

34

Agriculture Handbook 590

Table 11 Depth of flow (Hp) and slope range at retardance values for various discharges, velocities, and crest lengths

Maximum Discharge - - - - - - - - - - - - - - - - - - - - - - - - Hp - - - - - - - - - - - - - - - -- - - - - - - - Slope- - - - -

velocity - - - - - - - - - - - - - - - - - - - - - - - - L - - - - - - - - - - - - - - - -- - - - Min. Max.

25 50 100 200

(ft/s) (ft3/s/ft) (ft) (ft) (ft) (ft) (%) (%)

Retardance A 3 3 2.3 2.5 2.7 3.1 1 11

4 4 2.3 2.5 2.8 3.1 1 12

4 5 2.5 2.6 2.9 3.2 1 7

5 6 2.6 2.7 3.0 3.3 1 9

6 7 2.7 2.8 3.1 3.5 1 12

7 10 3.0 3.2 3.4 3.8 1 9

8 12.5 3.3 3.5 3.7 4.1 1 10

Retardance B 2 1 1.2 1.4 1.5 1.8 1 12

2 1.25 1.3 1.4 1.6 1.9 1 7

3 1.5 1.3 1.5 1.7 1.9 1 12

3 2 1.4 1.5 1.7 1.9 1 8

4 3 1.6 1.7 1.9 2.2 1 9

5 4 1.8 1.9 2.1 2.4 1 8

6 5 1.9 2.1 2.3 2.5 1 10

7 6 2.1 2.2 2.4 2.7 1 11

8 7 2.2 2.4 2.6 2.9 1 12

Retardance C 2 0.5 0.7 0.8 0.9 1.1 1 6

2 1 0.9 1.0 1.2 1.3 1 3

3 1.25 0.9 1.0 1.2 1.3 1 6

4 1.5 1.0 1.1 1.2 1.4 1 12

4 2 1.1 1.2 1.4 1.6 1 7

5 3 1.3 1.4 1.6 1.8 1 6

6 4 1.5 1.6 1.8 2.0 1 12

8 5 1.7 1.8 2.0 2.2 1 12

9 6 1.8 2.0 2.1 2.4 1 12

9 7 2.0 2.1 2.3 2.5 1 10

10 7.5 2.1 2.2 2.4 2.6 1 12

Retardance D 2 0.5 0.6 0.7 0.8 0.9 1 6

3 1 0.8 0.9 1.0 1.1 1 6

3 1.25 0.8 0.9 1.0 1.2 1 4

4 1.25 0.8 0.9 1.0 1.2 1 10

4 2 1.0 1.1 1.3 1.4 1 4

5 1.5 0.9 1.0 1.2 1.3 1 12

5 2 1.0 1.2 1.3 1.4 1 9

5 3 1.2 1.3 1.5 1.7 1 4

6 2.5 1.1 1.2 1.4 1.5 1 11

6 3 1.2 1.3 1.5 1.7 1 7

7 3 1.2 1.3 1.5 1.7 1 12

7 4 1.4 1.5 1.7 1.9 1 7

8 4 1.4 1.5 1.7 1.9 1 12

8 5 1.6 1.7 1.9 2.0 1 8

10 6 1.8 1.9 2.0 2.2 1 12
35

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Table 11 Depth of flow (Hp) and slope range at retardance values for various discharges, velocities, and crest lengths—

Continued.

Maximum Discharge - - - - - - - - - - - - - - - - - - - - - - - - Hp - - - - - - - - - - - - - - - -- - - - - - - - Slope- - - - -

velocity - - - - - - - - - - - - - - - - - - - - - - - - L - - - - - - - - - - - - - - - -- - - - Min. Max.

25 50 100 200

(ft/s) (ft3/s/ft) (ft) (ft) (ft) (ft) (%) (%)

Retardance E 2 0.5 0.5 0.5 0.6 0.7 1 2

3 0.5 0.5 0.5 0.6 0.7 1 9

3 1 0.7 0.7 0.8 0.9 1 3

4 1 0.7 0.7 0.8 0.9 1 6

4 1.25 0.7 0.8 0.9 1.0 1 5

5 1 0.7 0.7 0.8 0.9 1 12

5 2 0.9 1.0 1.1 1.2 1 4

6 1.5 0.8 0.9 1.0 1.1 1 12

6 2 0.9 1.0 1.1 1.2 1 7

6 3 1.2 1.2 1.3 1.5 1 4

7 2 0.9 1.0 1.1 1.2 1 12

7 3 1.2 1.2 1.3 1.5 1 7

8 3 1.2 1.2 1.3 1.5 1 10

8 4 1.4 1.4 1.5 1.7 1 6

10 4 1.4 1.4 1.5 1.7 1 12
Ponds—Planning, Design, Construction

36

Agriculture Handbook 590

Pipes through the dam

Pipe spillways—Protect the vegetation in earth

spillway channels against saturation from spring flow

or low flows that may continue for several days after a

storm. A pipe placed under or through the dam provides this protection. The crest elevation of the entrance should be 12 inches or more below the top of

the control section of the auxiliary spillway.

The pipe should be large enough to discharge flow

from springs, snowmelt, or seepage. It should also

have enough capacity to discharge prolonged surface

flow following an intense storm. This rate of flow

generally is estimated. If both spring flow and prolonged surface flow can be expected, the pipe should

be large enough to discharge both.

Drop inlet and hood inlet pipe spillways are commonly

used for ponds.

Figure 22 Drop-inlet pipe spillway with antiseep collar

Drop-inlet pipe spillway—A drop-inlet consists of a

pipe barrel (fig. 22) located under the dam and a riser

connected to the upstream end of the barrel. This riser

can also be used to drain the pond if a suitable valve or

gate is attached at its upstream end (fig. 23).

With the required discharge capacity determined, use

table 12 or 13 to select an adequate pipe size for the

barrel and riser. Table 12 is for barrels of smooth

pipe, and table 13 is for barrels of corrugated metal

pipe. The diameter of the riser must be somewhat

larger than the diameter of the barrel if the tube is to

flow full. Recommended combinations of barrel and

riser diameters are shown in the tables. In these tables

the total head is the vertical distance between a point

1 foot above the riser crest and the centerline of the

barrel at its outlet end. Because pipes of small diameter are easily clogged by trash and rodents, no pipe

smaller than 6 inches in diameter should be used for

the barrel.
37

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Figure 23 Drop-inlet pipe spillways

(a) With sand-gravel filter

(b) With antiseep collar









































 



 













Trash rack

Coupling Concrete base Filter diaphragm

Sand-gravel filter

Rock cover

Core fill

Berm

Pipe

Ground

surface

Valve well

Pond

Trash

guard Ground

surface















Trash rack

Coupling

Concrete base

Antiseep

collar

Core fill

Pipe

Berm

Valve well

Pond

Trash

guard
Ponds—Planning, Design, Construction

38

Agriculture Handbook 590

Table 12 Discharge values for smooth pipe drop inlets 1/

Total head Ratio of barrel diameter to riser diameter (in)

6:8 8:10 10:12 12:15 15:24 18:36

(ft) (ft3/s) (ft3/s) (ft3/s) (ft3/s) (ft3/s) (ft3/s)

6 1.54 3.1 5.3 8.1 13.6 20.6

8 1.66 3.3 5.7 8.9 14.8 22.5

10 1.76 3.5 6.1 9.6 15.8 24.3

12 1.86 3.7 6.5 10.2 16.8 26.1

14 1.94 3.9 6.8 10.7 17.8 27.8

16 2.00 4.0 7.0 11.1 18.6 29.2

18 2.06 4.1 7.2 11.5 19.3 30.4

20 2.10 4.2 7.4 11.8 19.9 31.3

22 2.14 4.3 7.6 12.1 20.5 32.2

24 2.18 4.4 7.8 12.4 21.0 33.0

26 2.21 4.5 8.0 12.6 21.5 33.8

1/ Length of pipe barrel used in calculations is based on a dam with a 12-foot top width and 2.5:1 side slopes. Discharge values are based on a

minimum head on the riser crest of 12 inches. Pipe flow based on Manning’s n = 0.012.

Table 13 Discharge values for corrugated metal pipe drop inlets 1/

Total head Ratio of barrel diameter to riser diameter (in)

6:8 8:10 10:12 12:15 15:21 18:24

(ft) (ft3/s) (ft3/s) (ft3/s) (ft3/s) (ft3/s) (ft3/s)

6 0.85 1.73 3.1 5.1 8.8 14.1

8 0.90 1.85 3.3 5.4 9.4 15.0

10 0.94 1.96 3.5 5.7 9.9 15.9

12 0.98 2.07 3.7 6.0 10.4 16.7

14 1.02 2.15 3.8 6.2 10.8 17.5

16 1.05 2.21 3.9 6.4 11.1 18.1

18 1.07 2.26 4.0 6.6 11.4 18.6

20 1.09 2.30 4.1 6.7 11.7 18.9

22 1.11 2.34 4.2 6.8 11.9 19.3

24 1.12 2.37 4.2 6.9 12.1 19.6

26 1.13 2.40 4.3 7.0 12.3 19.9

1/ Length of pipe barrel used in calculations is based on a dam with a 12-foot top width and 2.5:1 side slopes. Discharge values are based on a

minimum head on the riser crest of 12 inches. Pipe flow based on Manning’s n = 0.012.
39

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Hood-inlet pipe spillway—A hood-inlet consists of a

pipe laid in the earthfill (fig. 24). The inlet end of the

pipe is cut at an angle to form a hood. An antivortex

device, usually metal, is attached to the entrance of

the pipe to increase the hydraulic efficiency of the

tube. Typical installations of hood inlets and details of

the antivortex device are shown in figure 25. Often a

hood-inlet can be built at less cost than a drop-inlet

because no riser is needed. The major disadvantage of

this kind of pipe spillway is that it cannot be used as a

drain.

Figure 24 Dam with hooded inlet pipe spillway

(b) With antiseep collar

(a) With sand-gravel filter      Dam     

Hooded

inlet

Pond Pipe

Support for cantilever

outlet (optional)

Core

fill

Antiseep

collar

              







Dam

Hooded

inlet

Core

fill

Pond Pipe

Support for cantilever

outlet (optional)

Rock

cover

Filter diaphragm

Sand-gravel

filter
Ponds—Planning, Design, Construction

40

Agriculture Handbook 590

Figure 25 Pipe inlet spillways that have trash rack and antivortex baffle

C.M. pipe

riser with

tee section

welded to it

Reinforced

concrete base

Steel rod

trash rack

Antivortex

baffle plate





C.M. pipe

riser

1-in diameter

pipe

Locknut and washer

on each side

4-in by 4-in

post

2-in by 12-in

plank



Steel rods













Pipe

Angle iron

Antivortex baffle

Reinforced

concrete apron

Flat iron

Steel rod

Brace

Flat iron
41

Agriculture Handbook 590 Ponds—Planning, Design, Construction

The required diameter for a hood-inlet pipe can be

selected from table 14 or 15 after estimating the discharge capacity, Q, and determining the total head, H.

The tables also show the minimum head, h, required

above the invert or crest elevation of the pipe entrance. Unless you provide this minimum head, the

pipe will not flow full.

Pipe made of cast iron, smooth steel, concrete, plastic,

or corrugated metal is suitable for either kind of pipe

spillway. All joints must be watertight. A concrete

cradle or bedding is needed for concrete pipe to ensure a firm foundation and good alignment of the

conduit. Seal the joints of concrete pipe with an approved type of rubber gasket to give them the desired

amount of flexibility. For all pipe spillways, use new

pipe or pipe so slightly used that it may be considered

equivalent to new pipe.

To retard seepage through the embankment along the

outside surface of the pipe, compact the fill around the

pipe and use a filter and drainage diaphragm around

the pipe like that shown in figure 24.

One filter and drainage diaphragm should be used

around any structure that extends through the embankment to the downstream slope. The diaphragm

should be located downstream of the centerline of a

homogeneous embankment or downstream of the

cutoff trench. The diaphragm should be a minimum of

3 feet thick and extend around the pipe surface a

minimum of 2 times the outside diameter of the pipe

(2Do). When a cradle or bedding is used under the

pipe, the vertical downward 2Do is measured from the

bottom of the cradle or bedding. If bedrock is encountered within the 2Do measurement, the diaphragm

should terminate at the bedrock surface. The location

Table 14 Minimum head, h (ft), required above the invert of hood inlets to provide full flow, Q (ft3/s), for various sizes of

smooth pipe and values of total head, H 1/

Total head Diameter of pipe in inches

(ft) 6 8 10 12 15 18

6 h = 0.63 h = 0.85 h = 1.04 h = 1.23 h = 1.54 h = 1.82

Q = 1.63 Q = 3.0 Q = 5.3 Q = 8.5 Q = 14.0 Q = 21.2

8 h = 0.65 h = 0.86 h = 1.06 h = 1.27 h = 1.57 h = 1.87

Q = 1.78 Q = 3.5 Q = 6.0 Q = 9.3 Q = 15.5 Q = 23.3

10 h = 0.66 h = 0.87 h = 1.08 h = 1.30 h = 1.60 h = 1.91

Q = 1.93 Q = 3.8 Q = 6.6 Q = 10.2 Q = 17.0 Q = 25.4

12 h = 0.67 h = 0.88 h = 1.09 h = 1.32 h = 1.63 h = 1.94

Q = 2.06 Q = 4.1 Q = 7.1 Q = 10.9 Q = 18.3 Q = 27.5

14 h = 0.67 h = 0.89 h = 1.11 h = 1.33 h = 1.65 h = 1.96

Q = 2.18 Q = 4.3 Q = 7.5 Q = 11.6 Q = 19.5 Q = 29.4

16 h = 0.68 h = 0.90 h = 1.13 h = 1.35 h = 1.67 h = 1.98

Q = 2.28 Q = 4.5 Q = 7.8 Q = 12.2 Q = 20.5 Q = 31.0

18 h = 0.69 h = 0.91 h = 1.14 h = 1.36 h = 1.69 h = 2.00

Q = 2.36 Q = 4.7 Q = 8.1 Q = 12.7 Q = 21.4 Q = 32.5

20 h = 0.69 h = 0.92 h = 1.15 h = 1.37 h = 1.70 h = 2.02

Q = 2.43 Q = 4.9 Q = 8.4 Q = 13.2 Q = 22.2 Q = 33.9

22 h = 0.70 h = 0.93 h = 1.16 h = 1.38 h = 1.71 h = 2.04

Q = 2.50 Q = 5.0 Q = 8.7 Q = 13.6 Q = 23.0 Q = 35.1

24 h = 0.70 h = 0.93 h = 1.16 h = 1.39 h = 1.72 h = 2.05

Q = 2.56 Q = 5.1 Q = 9.0 Q = 14.0 Q = 23.7 Q = 36.3

26 h = 0.71 h = 0.94 h = 1.17 h = 1.40 h = 1.73 h = 2.07

Q = 2.60 Q = 5.2 Q = 9.3 Q = 14.4 Q = 24.4 Q = 37.5

1/ Length of pipe used in calculations is based on a dam with a 12-foot top width and 2.5:1 side slopes. Pipe flow based on Manning’s n = 0.012.
Ponds—Planning, Design, Construction

42

Agriculture Handbook 590

Table 15 Minimum head, h (ft), required above the invert of hood inlets to provide full flow, Q (ft3/s), for various sizes of

corrugated pipe and values of total head, H 1/

Total head Diameter of pipe in inches

(ft) 6 8 10 12 15 18

6 h = 0.59 h = 0.78 h = 0.97 h = 1.17 h = 1.46 h = 1.75

Q = 0.92 Q = 1.9 Q = 3.3 Q = 5.3 Q = 9.1 Q = 14.5

8 h = 0.59 h = 0.79 h = 0.98 h = 1.18 h = 1.48 h = 1.77

Q = 1.00 Q = 2.1 Q = 3.6 Q = 5.8 Q = 10.0 Q = 16.0

10 h = 0.60 h = 0.79 h = 0.99 h = 1.19 h = 1.49 h = 1.79

Q = 1.06 Q = 2.2 Q = 3.9 Q = 6.3 Q = 10.9 Q = 17.3

12 h = 0.60 h = 0.80 h = 1.00 h = 1.20 h = 1.50 h = 1.80

Q = 1.12 Q = 2.3 Q = 4.2 Q = 6.7 Q = 11.6 Q = 18.5

14 h = 0.61 h = 0.81 h = 1.01 h = 1.21 h = 1.51 h = 1.82

Q = 1.18 Q = 2.4 Q = 4.4 Q = 7.1 Q = 12.2 Q = 19.6

16 h = 0.61 h = 0.81 h = 1.01 h = 1.21 h = 1.52 h = 1.82

Q = 1.22 Q = 2.5 Q = 4.6 Q = 7.4 Q = 12.7 Q = 20.5

18 h = 0.61 h = 0.81 h = 1.02 h = 1.22 h = 1.53 h = 1.83

Q = 1.26 Q = 2.6 Q = 4.8 Q = 7.6 Q = 13.2 Q = 21.3

20 h = 0.62 h = 0.82 h = 1.03 h = 1.23 h = 1.54 h = 1.85

Q = 1.30 Q = 2.7 Q = 4.9 Q = 7.8 Q = 13.7 Q = 21.9

22 h = 0.62 h = 0.83 h = 1.03 h = 1.24 h = 1.55 h = 1.86

Q = 1.33 Q = 2.8 Q = 5.0 Q = 8.0 Q = 14.1 Q = 22.5

24 h = 0.63 h = 0.83 h = 1.04 h = 1.25 h = 1.56 h = 1.88

Q = 1.35 Q = 2.8 Q = 5.1 Q = 8.2 Q = 14.5 Q = 23.0

26 h = 0.63 h = 0.84 h = 1.05 h = 1.26 h = 1.58 h = 1.89

Q = 1.37 Q = 2.9 Q = 5.2 Q = 8.3 Q = 14.7 Q = 23.4

1/ Length of pipe used in calculations is based on a dam with a 12-foot top width and 2.5:1 side slopes. Pipe flow based on Manning’s n = 0.025.

of the diaphragm should never result in a minimum

soil cover over a portion of the diaphragm measured

normal to the nearest embankment surface of less

than 2 feet. If this requirement is exceeded, the filter

and drainage diaphragm should be moved upstream

until the 2-foot minimum is reached. The outlet for the

filter and drainage diaphragm should extend around

the pipe surface a minimum of 1.5 times the outside

diameter of the pipe (1.5Do) that has 1 foot around the

pipe being a minimum.

In most cases where the embankment core consists of

fine-grained materials, such as sandy or gravely silts

and sandy or gravely clay (15 to 85 percent passing the

No. 200 sieve), an aggregate conforming to ASTM C-33

fine concrete aggregate is suitable for the filter and

drainage diaphragm material. A fat clay or elastic silt

(more than 85 percent passing No. 200 sieve) core

requires special design considerations, and an engineer experienced in filter design should be consulted.

Using a filter and drainage diaphragm has many advantages. Some are as follows:

• They provide positive seepage control along

structures that extend through the fill.

• Unlike concrete antiseep collars, they do not

require curing time.

• Installation is easy with little opportunity for

constructed failure. The construction can consist

mostly of excavation and backfilling with the

filter material at appropriate locations.

Antiseep collars can be used instead of the filter and

drainage diaphragm. Antiseep collars have been used
43

Agriculture Handbook 590 Ponds—Planning, Design, Construction

with pipe spillways for many years. More fabricated

materials are required for this type of installation.

Both types of seepage control are acceptable; in either

case, proper installation is imperative.

If an antiseep collar is used, it should extend into the

fill a minimum of 24 inches perpendicular to the pipe.

If the dam is less than 15 feet high, one antiseep collar

at the centerline of the fill is enough. For higher dams,

use two or more collars equally spaced between the

fill centerline and the upstream end of the conduit

when a hood-inlet pipe is used. If a drop-inlet pipe is

used, the antiseep collars should be equally spaced

between the riser and centerline of the fill.

Use trash racks to keep pipes from clogging with trash

and debris. Of the many kinds of racks that have been

used, the three shown in figure 25 have proved the

most successful.

Extend the pipe 6 to 10 feet beyond the downstream

toe of the dam to prevent damage by the flow of water

from the pipe. For larger pipes, support the extension

with a timber brace.

Drainpipes—Some state regulatory agencies require

that provision be made for draining ponds completely

or for fluctuating the water level to eliminate breeding

places for mosquitoes. Whether compulsory or not,

provision for draining a pond is desirable and recommended. It permits good pond management for fish

production and allows maintenance and repair without cutting the fill or using siphons, pumps, or other

devices to remove the water. Install a suitable gate or

other control device and extend the drainpipe to the

upstream toe of the dam to drain the pond.

Water-supply pipes—Provide a water-supply pipe

that runs through the dam if water is to be used at

some point below the dam for supplying a stockwater

trough, for irrigation, or for filling an orchard spray

tank (fig. 26). This pipe is in addition to the principal

spillway. A water-supply pipe should be rigid and have

watertight joints, a strainer at its upper end, and a

valve at its outlet end. For a small rate of flow, such as

that needed to fill stockwater troughs, use steel or

plastic pipe that is l-l/2 inches in diameter. For a larger

rate of flow, such as that needed for irrigation, use

steel, plastic, or concrete pipe of larger diameter.

Water-supply pipes also should have watertight joints

and antiseep collars or a filter and drainage diaphragm.
Ponds—Planning, Design, Construction

44

Agriculture Handbook 590

Figure 26 Water is piped through the dam’s drainpipe to a stockwater trough

(a) Pipe with sand-gravel filter

 









Pond

6-inch concrete base

Extended pipe above water level

to show location of intake

Riser with

1/4-inch holes

Corrugated metal

pipe with 1-inch holes.

Pipe filled with coarse

gravel

Valve

Trough

Bell tile around valve and

pipe for suitable housing

Union

Core

fill

Ground surface

Filter diaphragm Sand-gravel filter

Rock

cover

Cap connection

may be used

for other purposes

Control

valve

(b) Pipe with antiseep collars



Pond

Extended pipe above water level

to show location of intake

Riser with

1/4-inch holes

Corrugated metal

pipe with 1-inch holes.

Pipe filled with coarse

gravel Valve Trough

Bell tile around valve and

pipe for suitable housing

Union

Control valve

Core fill

Antiseep collar

6-inch concrete base Cap connection

may be used

for other purposes
45

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Planning an earthfill dam

Foundations—You can build a safe earthfill dam on

almost any foundation if you thoroughly investigate

the foundation and adapt the design and construction

to the conditions. Some foundation conditions require

expensive construction measures that cannot be

justified for small ponds.

The most satisfactory foundation consists of soil

underlain at a shallow depth by a thick layer of relatively impervious consolidated clay or sandy clay. If a

suitable layer is at or near the surface, no special

measures are needed except removing the topsoil and

scarifying or disking to provide a bond with the material in the dam.

If the foundation is sand or a sand-gravel mixture and

there is no impervious clay layer at a depth that can be

reached economically with available excavating equipment, an engineer should design the dam. Although

such foundations may be stable, corrective measures

are needed to prevent excessive seepage and possible

failure. A foundation, consisting of or underlain by a

highly plastic clay or unconsolidated material requires

careful investigation and design to obtain stability. If

the foundation consists of such materials, consult an

engineer.

Water impounded on a bedrock foundation seldom

gives cause for concern unless the rock contains

seams, fissures, or crevices through which water may

escape at an excessive rate. Where rock is in the

foundation, investigate the nature of the rock carefully.

Cutoffs—If the dam’s foundation is overlain by alluvial deposits of pervious sands and gravels at or near

the surface and rock or clay at a greater depth, seepage in the pervious stratum must be reduced to prevent possible failure of the dam by piping. To prevent

excessive seepage, you need a cutoff to join the impervious stratum in the foundation with the base of the dam.

The most common kind of cutoff is made of compacted clayey material. A trench is excavated along

the centerline of the dam deep enough to extend well

into the impervious layer (fig. 27). This trench extends

into and up the abutments of the dam as far as there is

any pervious material that might allow seepage. The

bottom of the trench should be no less than 8 feet

wide (or the bulldozer blade width, whichever is

greater), and the sides no steeper than 1.5:1. Fill the

trench with successive thin layers (9-inch maximum)

of clay or sandy clay material. Compact each layer

thoroughly at near-optimum moisture conditions

before placing the next layer. The moisture content is

adequate for compaction when the material can be

formed into a firm ball that sticks together and remains intact when the hand is vibrated violently and

no free water appears.

Top width and alignment—For dams less than 10

feet high, a conservative minimum top width is 6 feet.

As the height of the dam increases, increase the top

width. The recommended minimum top width for

earth embankments of various heights is:

Height of dam Minimum top width

 (ft) (ft)

Under 10 6

11 to 14 8

15 to 19 10

20 to 24 12

25 to 34 14

If the top of the embankment is to be used for a roadway, provide for a shoulder on each side of the roadway to prevent raveling. The top width should be at

least 16 feet. In some situations a curved dam alignFigure 27 A core trench is cut on the centerline of a dam
Ponds—Planning, Design, Construction

46

Agriculture Handbook 590

ment is more desirable than a straight alignment.

Curvature can be used to retain existing landscape

elements, reduce the apparent size of the dam, blend

the dam into surrounding natural landforms, and

provide a natural-appearing shoreline.

Side slopes—The side slopes of a dam depend primarily on the stability of the fill and on the strength and

stability of the foundation material. The more stable

the fill material, the steeper the side slopes. Unstable

materials require flatter side slopes. Recommended

slopes for the upstream and downstream faces of

dams built of various materials are shown in table 16.

For stability, the slopes should not be steeper than

those shown in table 16, but they can be flatter as long

as they provide surface drainage. The side slopes need

not be uniform, but can be shaped to blend with the

surrounding landforms (fig. 28).

Finish-grading techniques used to achieve a smooth

landform transition include slope rounding and slope

warping. Slope rounding is used at the top and bottom

of cuts or fills and on side slope intersections. Slope

warping is used to create variety in the horizontal and

vertical pitch of finished slopes (fig. 29). Additional fill

can be placed on the backslope and abutments of the

dam, if needed, to achieve this landform transition.

Freeboard—Freeboard is the additional height of the

dam provided as a safety factor to prevent overtopping

by wave action or other causes. It is the vertical distance between the elevation of the water surface in the

pond when the spillway is discharging at designed

depth and the elevation of the top of the dam after all

Table 16 Recommended side slopes for earth dams

 Slope

Fill material Upstream Downstream

Clayey sand, clayey gravel, sandy 3:1 2:1

clay, silty sand, silty gravel

Silty clay, clayey silt 3:1 3:1

settlement. If your pond is less than 660 feet long,

provide a freeboard of no less than l foot. The minimum freeboard is 1.5 feet for ponds between 660 and

1,320 feet long, and is 2 feet for ponds up to a half mile

long. For longer ponds an engineer should determine

the freeboard.

Settlement allowance—Settlement or consolidation

depends on the character of the materials in both the

dam and the foundation and on the construction

method. To allow for settlement, build earth dams

somewhat higher than the design dimensions. If your

dam is adequately compacted in thin layers under

good moisture conditions, there is no reason to expect

any appreciable settlement in the dam itself, but the

foundation may settle. For a compacted fill dam on

unyielding foundation, settlement is negligible.

Most foundations are yielding, and settlement may

range from l to 6 percent of the height of the dam,

mainly during construction. The settlement allowance

for a rolled-fill dam should be about 5 percent of the

designed dam height. In other words, the dam is built

5 percent higher than the designed height. After settlement, the height of the dam will be adequate. Most

pond dams less than 20 feet high, however, are not

rolled fill. For these dams the total settlement allowance should be about 10 percent.

Estimating the volume of the earthfiIl—After

planning is completed, estimate the number of cubic

yards of earthfill required to build the dam. Also estimate excavation yardage in foundation stripping, core

trench excavation, and any other significant excavations. This helps predict the cost of the dam

Figure 28 Dam side slopes are curved and shaped to

blend with surrounding topography
47

Agriculture Handbook 590 Ponds—Planning, Design, Construction

and serves as a basis for inviting bids and for awarding

a construction contract. The estimate of the volume of

earthfill should include

 • volume in the dam itself including the allowance

for settlement,

• volume required to backfill the cutoff trench,

• volume required to backfill stream channels or

holes in the foundation area, and

 • any other volume of earthfill the contractor is

required to move.

Volume estimates for dams generally are made of the

required number of cubic yards of earthfill in place.

Probably the most efficient method of estimating the

volume of earthfill is the sum-of-end-area method. The

ground surface elevations at all points along the

centerline of the dam where the slope changes significantly are established by the centerline profile. With

the settled top elevation of the dam established, you

Figure 29 Finished grading techniques

can obtain the settle fill height at each of these points

by subtracting the ground surface elevation from the

settle top elevation. With the fill heights, side slopes,

and top width established, find the end areas at each

of these stations along the centerline in table 17.

For example, assume that a dam has slopes of 3:1 on

both upstream and downstream sides and a top width

of 12 feet. For a point along the centerline where the

fill is 15 feet high, the table shows that the end area at

that point is 675 plus 180, or 855 square feet. The

number of cubic yards of fill between two points on

the centerline of the dam is equal to the sum of the end

areas at those two points multiplied by the distance

between these points and divided by 54. The total

volume of earthfill in the dam is the sum of all such

segments. A sample volume estimate illustrating the

use of the sum-of-end-areas method is shown in table 18.





Not this

This

Not this

This

(a) Slope rounding (b) Slope warping
Ponds—Planning, Design, Construction

48

Agriculture Handbook 590

Table 17 End areas in square feet of embankment sections for different side slopes and top widths 1/

 - - - - - - - - - - - - - Side slopes - - - - - - - - - - - - - - - - - - - - - - - - - - Top width (ft) - - - - - - - - - - - -

2.5:1 2.5:1 3:1 3.5:1 4:1

 Fill height 2.5:1 3:1 3:1 3.5:1 4:1 8 10 12 14 16

(ft) 2:1 2:1 2.5:1 3:1 3:1

 3:1 3.5:1 3.5:1 4:1 5:1

1.0 3 3 3 4 4 8 10 12 14 16

1.2 4 4 4 5 6 10 12 14 17 19

1.4 5 5 6 7 8 11 14 17 20 22

1.6 6 7 8 9 10 13 16 19 22 26

1.8 8 9 10 11 13 14 18 22 25 29

2.0 10 11 12 14 16 16 20 24 28 32

2.2 12 13 15 17 19 18 22 27 31 35

2.4 14 16 17 20 23 19 24 29 34 39

2.6 17 19 20 24 27 21 26 31 36 42

2.8 20 22 23 27 31 22 28 34 39 45

3.0 22 25 27 32 36 24 30 36 42 48

3.2 26 28 31 36 41 26 32 38 45 51

3.4 29 32 35 40 46 27 34 41 47 55

3.6 32 36 39 45 52 29 36 43 50 58

3.8 36 40 43 50 58 30 38 46 53 61

4.0 40 44 48 56 64 32 40 48 56 64

4.2 44 49 53 62 71 34 42 50 59 67

4.4 48 53 58 68 77 35 44 53 61 71

4.6 53 58 63 74 85 37 46 55 64 74

4.8 57 63 69 81 92 38 48 57 67 77

5.0 62 69 75 87 100 40 50 60 70 80

5.2 67 74 81 94 108 42 52 62 73 83

5.4 73 80 87 102 117 43 54 65 75 87

5.6 78 86 94 110 125 45 56 67 78 90

5.8 84 93 101 118 135 46 58 69 81 93

6.0 90 99 108 126 144 48 60 72 84 96

6.2 96 106 115 135 154 50 62 74 87 99

6.4 102 113 123 143 164 51 64 77 89 103

6.6 109 120 131 152 174 53 66 79 92 106

6.8 116 128 139 162 185 54 68 81 95 109

7.0 123 135 147 172 196 56 70 84 98 112

7.2 130 143 156 182 207 58 72 86 101 115

7.4 138 152 165 193 219 59 74 89 103 119

7.6 145 159 174 203 231 61 76 91 106 122

7.8 153 168 183 214 243 62 78 93 109 125

8.0 160 176 192 224 256 64 80 96 112 128

8.2 169 185 202 235 269 66 82 98 115 131

8.4 177 194 212 247 282 67 84 101 117 135

8.6 186 204 222 259 296 69 86 103 120 138

8.8 194 213 232 271 310 70 88 105 123 141

See footnote at end of table.
49

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Table 17 End areas in square feet of embankment sections for different side slopes and top widths 1/—Continued.

 - - - - - - - - - - - - - Side slopes - - - - - - - - - - - - - - - - - - - - - - - - - - Top width (ft) - - - - - - - - - - - -

2.5:1 2.5:1 3:1 3.5:1 4:1

 Fill height 2.5:1 3:1 3:1 3.5:1 4:1 8 10 12 14 16

(ft) 2:1 2:1 2.5:1 3:1 3:1

 3:1 3.5:1 3.5:1 4:1 5:1

9.0 203 223 243 283 324 72 90 108 126 144

9.2 212 233 254 296 339 74 92 110 129 147

9.4 222 244 266 310 353 75 94 113 131 151

9.6 231 254 277 323 369 77 96 115 134 154

9.8 241 265 289 337 384 78 98 117 137 157

10.0 250 275 300 350 400 80 100 120 140 160

10.2 260 286 313 364 416 102 122 143 163

10.4 271 298 325 379 433 104 125 145 167

10.6 281 309 338 394 449 106 127 148 170

10.8 292 321 350 409 467 108 129 151 173

11.0 302 333 363 424 484 110 132 154 176

11.2 313 344 376 440 502 112 134 157 179

11.4 325 357 390 456 520 114 137 159 183

11.6 336 370 404 472 538 116 139 162 186

11.8 348 383 418 488 557 118 141 165 189

12.0 360 396 432 504 576 120 144 168 192

12.2 372 409 447 522 595 122 146 171 195

12.4 385 424 462 539 615 124 149 173 199

12.6 397 437 477 557 635 126 151 176 202

12.8 410 451 492 574 655 128 153 179 205

13.0 422 465 507 592 676 130 156 182 208

13.2 436 479 523 610 697 132 158 185 211

13.4 449 494 539 629 718 134 161 187 215

13.6 463 509 555 648 740 136 163 190 218

13.8 476 523 571 667 762 138 166 193 221

14.0 490 539 588 686 784 140 168 196 224

14.2 505 555 605 706 807 142 170 199 227

14.4 519 570 622 726 829 144 173 202 230

14.6 534 586 639 746 853 146 175 204 234

14.8 548 602 657 767 876 148 178 207 237

15.0 563 619 675 788 900 150 180 210 240

15.2 578 635 693 809 924 152 182 213 243

15.4 594 653 711 830 949 154 185 216 246

15.6 609 669 730 852 973 156 187 218 250

15.8 625 687 749 874 999 158 190 221 253

16.0 640 704 768 896 1,024 160 192 224 256

16.2 656 722 787 919 1,050 194 227 259

16.4 673 740 807 942 1,076 197 230 262

16.6 689 758 827 965 1,102 199 232 266

16.8 706 776 847 988 1,129 202 235 269

17.0 723 795 867 1,012 1,156 204 238 272

 See footnote at end of table.
Ponds—Planning, Design, Construction

50

Agriculture Handbook 590

Table 17 End areas in square feet of embankment sections for different side slopes and top widths 1/—Continued.

 - - - - - - - - - - - - - Side slopes - - - - - - - - - - - - - - - - - - - - - - - - - - Top width (ft) - - - - - - - - - - - -

2.5:1 2.5:1 3:1 3.5:1 4:1

 Fill height 2.5:1 3:1 3:1 3.5:1 4:1 8 10 12 14 16

(ft) 2:1 2:1 2.5:1 3:1 3:1

 3:1 3.5:1 3.5:1 4:1 5:1

17.2 740 814 888 1,036 1,183 206 241 275

17.4 757 833 909 1,060 1,211 209 244 278

17.6 774 852 930 1,084 1,239 211 246 282

17.8 792 871 951 1,109 1,267 214 249 285

18.0 810 891 972 1,134 1,296 216 252 288

18.2 828 911 994 1,160 1,325 218 255 291

18.4 846 931 1,016 1,186 1,354 221 258 294

18.6 865 951 1,038 1,212 1,384 223 260 298

18.8 884 972 1,060 1,238 1,414 226 263 301

19.0 903 993 1,083 1,264 1,444 228 266 304

19.2 922 1,014 1,106 1,291 1,475 230 269 307

19.4 941 1,035 1,129 1,318 1,505 233 272 310

19.6 960 1,056 1,152 1,345 1,537 235 274 314

19.8 980 1,078 1,176 1,372 1,568 238 277 317

20.0 1,000 1,100 1,200 1,400 1,600 240 280 320

20.2 1,020 1,122 1,224 1,428 1,632 242 283 323

20.4 1,040 1,144 1,248 1,457 1,665 245 286 326

20.6 1,061 1,167 1,273 1,486 1,697 247 288 330

20.8 1,082 1,190 1,298 1,515 1,731 250 291 333

21.0 1,103 1,213 1,323 1,544 1,764 252 294 336

21.2 1,124 1,236 1,348 1,574 1,798 254 297 339

21.4 1,145 1,254 1,374 1,604 1,832 257 300 342

21.6 1,166 1,283 1,400 1,634 1,866 259 302 346

21.8 1,188 1,307 1,426 1,664 1,901 262 305 349

22.0 1,210 1,331 1,452 1,694 1,936 264 308 352

22.2 1,232 1,356 1,479 1,725 1,971 266 311 355

22.4 1,254 1,380 1,506 1,756 2,007 269 314 358

22.6 1,277 1,405 1,533 1,788 2,043 271 316 362

22.8 1,300 1,430 1,560 1,820 2,079 274 319 365

23.0 1,323 1,455 1,587 1,852 2,116 276 322 368

1/ To find the end area for any fill height, add square feet given under staked side slopes to that under the top width for total section. Example:

6.4-foot 3:1 front and back slopes, 14-foot top width —123 plus 89, or 212 square feet for the section. Any combination of slopes that adds to

5, 6, or 7 may be used. A combination of 3.5:1 front and 2.5:1 back gives the same results as 3:1 front and back.
51

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Table 18 Volume of material needed for the earthfill

Station Ground elevation Fill height 1/ End area 2/ Sum of end areas Distance Double volume

(ft) (ft) (ft) (ft2) (ft2) (ft) (ft3)

0 + 50 35.0 0 0

 44 18 792

+ 68 32.7 2.3 44

401 32 12,832

1 + 00 25.9 9.1 357

1,066 37 39,442

+ 37 21.5 13.5 709

1,564 16 25,024

+ 53 20.0 15.0 855

1,730 22 38,060

+ 75 19.8 15.2 875

1,781 25 44,525

2 + 00 19.5 15.5 906

1,730 19 32,870

+ 19 20.3 14.7 824

1,648 13 21,424

+ 32 20.3 14.7 824

1,805 4 7,220

+ 36 18.8 16.2 981

2,030 4 8,120

+ 40 18.2 16.8 1,049

2,064 3 6,192

+ 43 18.5 16.5 1,015

1,911 3 5,733

+ 46 19.6 15.4 896

1,771 13 23,023

+ 59 19.8 15.2 875

1,650 41 67,650

3 + 00 20.8 14.2 775

1,023 35 35,805

+ 35 27.7 7.3 248

324 25 8,100

+ 60 31.6 3.4 76

76 36 2,736

3 + 96 35.0 .0 0

Total 379,548 3/

1/ Elevation of top of dam without allowance for settlement.

2/ End areas based on 12-foot top width and 3:1 slopes on both sides.

3/ Divide double volume in cubic feet by 54 to obtain volume in cubic yards; for example,

379 548

54

7 029

703

7 732

3

3

3

, ,

.

=

=

=

yd

yd

yd

Allowance for settlement (10%)

Total volume

}

}

}

}

}

}

}

}

}

}

}

}

}

}

}

}

}

.
Ponds—Planning, Design, Construction

52

Agriculture Handbook 590

The sample volume estimate of 7,732 cubic yards

includes only the volume of earth required to complete

the dam itself. Estimate the volume of earth required

to backfill the core trench, old stream channels, and

other required excavation and add it to the estimate

for the dam. Also include an estimate of additional fill

to be placed on the backslope and abutments. For

example, assume that, in addition to the volume

shown in table 18, there is a cutoff trench to be backfilled. The dimensions of the trench are:

Average depth = 4.0 ft

Bottom width = 8.0 ft

Side slopes = 1.5:1

Length = 177 ft

Compute the volume of backfill as follows:

End Area = +× [ ] w z dd ( ) [Eq. 4]

Volume

End area = ( ) × 1

27 [Eq. 5]

where:

d = average depth

w = bottom width

l = length

z = side slopes

End area = [8 + (1.5 x 4)]4 = 56 ft2

Volume yd = × = 56 177

27

367 2

Add this to the volume required for the dam and the

total volume is 7,732 plus 367, or 8,099 cubic yards.

This 8,099 cubic yards represents the required compacted volume. To account for shrinkage resulting

from compaction, a minimum of 1.5 times this amount

is generally necessary to have available in the borrow

areas and required excavations. In this example you

need a minimum of 12,148 cubic yards available to

construct the dam.

Drawings and specifications—Record on the engineering drawings all planning information that would

affect the construction of the dam. These drawings

should show all elevations and dimensions of the dam,

the dimensions and extent of the cutoff trench and

3

×

other areas requiring backfill, the location and dimensions of the principal spillway and other planned

appurtenances, and any other pertinent information.

The drawings should also include a list of the estimated quantity and kind of building materials required.

The construction and material specifications state the

extent and type of work, site specific details, material

quality, and requirements for prefabricated materials.

Observe all land disturbance laws by including temporary protective measures during construction to minimize soil erosion and sedimentation.

Unless you have all the necessary equipment, you will

need to employ a contractor to build the pond. You

may wish to receive bids from several contractors to

be sure that you are getting the job done at the lowest

possible cost. A set of drawings and specifications

shows what is to be done. This provides a basis for

contractors to bid on the proposed work, allows fair

competition among bidders, and states the conditions

under which the work is to be done. The specifications

should

• give all the information not shown on the drawings that is necessary to define what is to be done,

• prescribe how the work is to be done if such

direction is required,

• specify the quality of material and workmanship

required, and

• define the method of measurement and the unit

of payment for the various items of work that

constitute the whole job.

Construction work of the quality and standards desired will not result unless there is a clear understanding of these requirements between the owner and the

contractor. For these reasons specifications should be

prepared for all ponds for which the owners award the

construction contracts.

Assistance in preparing drawings and specifications is

available from your local soil conservation district,

NRCS specialists, or private consultants.

a

l
53

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Staking for construction

Each job must be adequately and clearly staked before

construction is started. Staking transmits the information on the drawings to the job site. This information

locates the work and provides the lines, grade, and

elevations required for construction in accordance

with the drawings. Consider the contractor’s wishes in

staking so that he can make the most effective use of

the stakes. The quality and appearance of the completed job reflect the care used in staking. The staking

should be done by an engineer or other qualified person.

The areas to be cleared generally consist of the dam

site, the auxiliary spillway site, the borrow area, and

the area over which water is to be impounded. Mark

each area clearly with an adequate number of stakes.

In the pond area, locate the proposed water line with a

level and surveying rod. This provides a base line from

which clearing limits can be established.

To locate the dam, set stakes along its centerline at

intervals of 100 feet or less. (Generally this has been

done during the initial planning survey.) Then set the

fill and slope stakes upstream and downstream from

the centerline stakes to mark the points of intersection

of the side slopes with the ground surface and to mark

the work area limits of construction. These stakes also

establish the height of the dam.

To locate the earth auxiliary spillway, first stake the

centerline and then set cut and slope stakes along the

lines of intersection of the spillway side slopes with

the natural ground surface.

If fill material must be obtained from a borrow area,

this area must be clearly marked. Set cut stakes to

indicate the depth to which the contractor can excavate to stay within the limits of suitable material, as

indicated by soil borings. This allows the borrow area

to drain readily and marks the limits of construction.

Set stakes to show the centerline location of the

principal spillway after foundation preparation has

reached the point at which the stakes will not be

disturbed. Locate the pipe where it will rest on a firm

foundation. Mark the stakes to show cuts from the top

of the stakes to the grade elevation of the pipe. With

additional stakes, mark the location of the riser, drainage gate, filter and drainage diaphragm or antiseep

collars, outlet structures, and other appurtenances.

Building the pond

Attention to the details of construction and adherence

to the drawings and specifications are as important as

adequate investigation and design. Careless and

shoddy construction can make an entirely safe and

adequate design worthless and cause failure of the

dam. Adherence to specifications and prescribed

construction methods becomes increasingly important

as the size of the structure and the failure hazards

increase. Good construction is important regardless of

size, and the cost is generally less in the long run than

it is for dams built carelessly.

Clearing and grubbing—Clear the foundation area

and excavated earth spillway site of trees and brush.

In some states this is required by statute. Cut trees and

brush as nearly flush with the ground as practicable

and remove them and any other debris from the dam

site. Should you or your contractor elect to uproot the

trees with a bulldozer, you must determine if the tree

roots extend into pervious material and if the resultant

holes will cause excessive seepage. If so, fill the holes

by placing suitable material in layers and compact

each layer by compacting or tamping.

All material cleared and grubbed from the pond site,

from the earth spillway and borrow areas, and from

the site of the dam itself should be disposed of. This

can be done by burning, burying under 2 feet of soil, or

burying in a disposal area, such as a sanitary landfill.

Minimal clearing conserves site character and minimizes the difficulty and expense of reestablishing

vegetation. Confine clearing limits to the immediate

construction areas to avoid unnecessary disturbance.

Figure 30 A tree well preserves vegetation
Ponds—Planning, Design, Construction

54

Agriculture Handbook 590

After filling the holes, thoroughly break the ground

surface and turn it to a depth of 6 inches. Roughly

level the surface with a disk harrow and then compact

it so that the surface materials of the foundation are

as well compacted as the subsequent layers of the fill. Dig

the cutoff trench to the depth, bottom width, and side

slopes shown on the drawings. Often the depths

shown on the drawings are only approximate; you

Removing all vegetation within the construction limits

is not always necessary. Selected groupings of desirable plants can be kept. Trees and shrubs can often

survive a 1- to 2-foot layer of graded fill over their root

systems or they can be root-pruned in excavated

areas. Tree wells and raised beds can also be used to

retain vegetation (fig. 30).

Clearing limits should be irregular to create a naturalappearing edge and open area (fig. 31). Further transition with vegetated surroundings can be accomplished

by feathering clearing edges. Density and height of

vegetation can be increased progressively from the

water’s edge to the undisturbed vegetation (fig. 32).

Feathering can be accomplished by selective clearing,

installation of new plants, or both.

Preparing the foundation—Preparing the foundation includes treating the surface, excavating and

backfilling the cutoff trench, and excavating and

backfilling existing stream channels. If the foundation

has an adequate layer of impervious material at the

surface or if it must be blanketed by such a layer, you

can eliminate the cutoff trench. Remove sod, boulders,

and topsoil from the entire area over which the embankment is to be placed. This operation is best performed by using a tractor-pulled or self-propelled

wheeled scraper. The topsoil should be stockpiled

temporarily for later use on the site.

Fill all holes in the foundation area, both natural and

those resulting from grubbing operations, with suitable fill material from borrow areas. Use the same

method of placement and compaction as used to build

the dam. Where necessary use hand or power tampers

in areas not readily accessible to other compacting

equipment.

Figure 31 Irregular clearing around the pond helps

create a natural appearing edge

Figure 32 Feathering vegetation at the pond's edge makes a natural transition with existing vegetation







    



  





This

Irregular clearing

edge

Straight clearing edge

Pond

Existing trees

Not this

Existing trees

Pond

Selective clearing

and/or plantings

Selective clearing and/or planting

creates a natural appearance

Not this

Minimum

clearing

limits

Clearing

limits

Existing trees Existing trees

Pond

Lack of transition treatment

creates an unnatural edge

This
55

Agriculture Handbook 590 Ponds—Planning, Design, Construction

need to inspect the completed trench before backfilling to be sure that it is excavated at least 12 inches

into impervious material throughout its entire length.

Material removed from the trench can be placed in the

downstream third of the dam and compacted in the

same manner as the earthfill if the material is free of

boulders, roots, organic matter, and other objectionable material.

A dragline excavator and a tractor-pulled or selfpropelled wheeled scraper are the most satisfactory

equipment for excavating cutoff trenches. Before

backfilling operations are attempted, pump all free

water from the cutoff trench. Some material high in

clay content takes up more than twice its own weight

of water and becomes a soggy mass. Such clay puddled in the cutoff of a dam may require many years to

become stable. Also, in drying it contracts and may

leave cracks that can produce a roof of the overlying

impervious earthfill section and provide passageways

for seepage through the dam.

Backfill the cutoff trench to the natural ground surface

with suitable fill material from designated borrow

areas. Place the backfill material in thin layers and

compact it by the same methods used to build the dam.

Deepen, slope back, and widen stream channels that

cross the embankment foundation. This is often necessary to remove all stones, gravel, sand, sediment,

stumps, roots, organic matter, and any other objectionable material that could interfere with proper bonding

of the earthfill with the foundation. Leave side slopes

of the excavated channels no steeper than 3:1 when

the channels cross the embankment centerline. If the

channels are parallel to the centerline, leave the side

slopes no steeper than 1:1. Backfill these channels as

recommended for the cutoff trench.

Installing the pipe spillway—Install the pipe, riser

(if applicable), filter and drainage diaphragm or antiseep collars, trash rack, and other mechanical components of the dam to the lines and grades shown on the

drawings and staked at the site. To minimize the

danger of cracks or openings at the joints caused by

unequal settlement of the foundation, place all pipes

and other conduits on a firm foundation.

Install pipes and filter and drainage diaphragm or

antiseep collars and tamp the selected backfill material around the entire structure before placing the

earthfill for the dam. The same procedure applies to

all other pipes or conduits.

Excavating the earth spillway—The completed

spillway excavation should conform as closely as

possible to the lines, grades, bottom width, and side

slopes shown on the drawings and staked at the site.

Leave the channel bottom transversely level to prevent meandering and the resultant scour within the

channel during periods of low flow. If it becomes

necessary to fill low places or depressions in the

channel bottom caused by undercutting the established grade, fill them to the established grade by

placing suitable material in 8-inch layers and compacting each layer under the same moisture conditions

regardless of the placement in or under the embankment.
Ponds—Planning, Design, Construction

56

Agriculture Handbook 590

Building the dam—Clear the dam and spillway area

of trees, brush, stumps, boulders, sod, and rubbish.

The sod and topsoil can be stockpiled and used later

to cover the dam and spillway (fig. 33). This will help

when vegetation is established. Get suitable fill material from previously selected borrow areas and from

sites of planned excavation. The material should be

free of sod, roots, stones more than 6 inches in diameter, and any material that could prevent the desired

degree of compaction. Do not use frozen material or

place fill material on frozen foundations.

Selected backfill material should be placed in the core

trench and around pipes and antiseep collars, when

used. The material should be compacted by hand

tamping or manually directed power tampers around

pipes. Begin placing fill material at the lowest point

and bring it up in horizontal layers, longitudinal to the

centerline of dam, approximately 6 inches thick. For

fill placement around risers, pipes and filter, and

drainage diaphragms, the horizontal layers should be

Figure 33 The sod and topsoil in a pond construction area can be stockpiled for later use

approximately 4 inches thick. Do not place fill in

standing water. The moisture content is adequate for

compaction when the material can be formed into a

firm ball that sticks together and remains intact when

the hand is vibrated violently and no free water appears. If the material can be formed into a firm ball

that sticks together, the moisture content is adequate

for compaction. Laboratory tests of the fill material

and field testing of the soil for moisture and compaction may be necessary for large ponds or special

conditions.

If the material varies in texture and gradation, use the

more impervious (clay) material in the core trench,

center, and upstream parts of the dam. Construction

equipment can be used to compact earthfill in an

ordinary pond dam. Equipment that has rubber tires

can be routed so each layer is sufficiently covered by

tire tracks. For dams over 20 feet high, special equipment, such as sheepsfoot rollers, should be used.
57

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Excavated ponds

Excavated ponds are the simplest to build in relatively

flat terrain. Because their capacity is obtained almost

solely by excavation, their practical size is limited.

They are best suited to locations where the demand

for water is small. Because excavated ponds can be

built to expose a minimum water surface area in

proportion to their volume, they are advantageous in

places where evaporation losses are high and water is

scarce. The ease with which they can be constructed,

their compactness, their relative safety from floodflow damage, and their low maintenance requirements

make them popular in many sections of the country.

Two kinds of excavated ponds are possible. One is fed

by surface runoff and the other is fed by ground water

aquifers, usually layers of sand and gravel. Some

ponds may be fed from both of these sources.

The general location of an excavated pond depends

largely on the purpose or purposes for which the

water is to be used and on other factors discussed

previously in this handbook. The specific location is

often influenced by topography. Excavated ponds fed

by surface runoff can be located in almost any kind of

topography. They are, however, most satisfactory and

most commonly used in areas of comparatively flat,

but well-drained terrain. A pond can be located in a

broad natural drainageway or to one side of a

drainageway if the runoff can be diverted into the

pond. The low point of a natural depression is often a

good location. After the pond is filled, excess runoff

escapes through regular drainageways.

Excavated ponds fed by ground water aquifers can be

located only in areas of flat or nearly flat topography.

If possible, they should be located where the permanent water table is within a few feet of the surface.

Soils

If an excavated pond is to be fed by surface runoff,

enough impervious soil at the site is essential to avoid

excess seepage losses. The most desirable sites are

where fine-textured clay and silty clay extend well

below the proposed pond depth. Sites where sandy

clay extends to adequate depths generally are satisfactory. Avoid sites where the soil is porous or is underlain by strata of coarse-textured sand or sand-gravel

mixtures unless you are prepared to bear the expense

of an artificial lining. Avoid soil underlain by limestone

containing crevices, sinks, or channels.

The performance of nearby ponds that are fed by

runoff and in a similar soil is a good indicator of the

suitability of a proposed site. Supplement such observations of existing ponds by boring enough test holes

at intervals over the proposed pond site to determine

accurately the kind of material there. You can get

some indication of permeability by filling the test holes

with water. The seepage indicates what to expect of a

pond excavated in the same kind of material.

If an excavated pond is to be fed from a water-bearing

sand or a sand-gravel layer, the layer must be at a

depth that can be reached practically and economically by the excavating equipment. This depth seldom

exceeds 20 feet. The water-bearing layer must be thick

enough and permeable enough to yield water at a rate

that satisfies the maximum expected demand for

water and overcomes evaporation losses.

Thoroughly investigate sites proposed for aquifer-fed

excavated ponds. Bore test holes at intervals over the

site to determine the existence and physical characteristics of the water-bearing material. The water level in

the test holes indicates the normal water level in the

completed pond. The vertical distance between this

level and the ground surface determines the volume of

overburden or excavation needed that does not contribute to the usable pond capacity, but may increase

the construction cost considerably. From an economic

standpoint, this vertical distance between water level

and ground surface generally should not exceed 6 feet.

Check the rate at which the water rises in the test

holes. A rapid rate of rise indicates a high-yielding

aquifer. If water is removed from the pond at a rapid

rate, as for irrigation, the water can be expected to

return to its normal level within a short time after

removal has ceased. A slow rate of rise in the test

holes indicates a low-yielding aquifer and a slow rate

of recovery in the pond. Check the test hole during

drier seasons to avoid being misled by a high water

table that is only temporary.
Ponds—Planning, Design, Construction

58

Agriculture Handbook 590

Spillway and inlet requirements

If you locate an excavated pond fed by surface runoff

on sloping terrain, you can use a part of the excavated

material for a small low dam around the lower end and

sides of the pond to increase its capacity. You need an

auxiliary spillway to pass excess storm runoff around

the small dam. Follow the procedures for planning the

spillway and provide protection against erosion as

discussed in the Excavating the earth spillway section.

Ponds excavated in areas of flat terrain generally

require constructed spillways. If surface runoff must

enter an excavated pond through a channel or ditch

rather than through a broad shallow drainageway, the

overfall from the ditch bottom to the bottom of the

pond can create a serious erosion problem unless the

ditch is protected. Scouring can occur in the side slope

of the pond and for a considerable distance upstream

in the ditch. The resulting sediment tends to reduce

the depth and capacity of the pond. Protect the slope

by placing one or more lengths of rigid pipe in the

ditch and extending them over the side slope of the

excavation. The extended part of the pipe or pipes can

be cantilevered or supported with timbers. The diameter of the pipes depends on the peak rate of runoff

that can be expected from a 10-year frequency storm.

If you need more than one pipe inlet, the combined

capacity should equal or exceed the estimated peak

rate of runoff.

Pipe diameter 1/ Pond inflow Q

(in) (ft3/s)

15 0 to 6

18 6 to 9

21 9 to 13

24 13 to 18

30 18 to 30

36 30 to 46

42 46 to 67

48 67 to 92

54 92 to 122

60 122 to 157

1/ Based on a free outlet and a minimum pipe slope of 1 percent

with the water level 0.5 foot above the top of the pipe at the

upstream end.

In areas where a considerable amount of silt is carried

by the inflowing water, you should provide a desilting

area or filterstrip in the drainageway immediately

above the pond to remove the silt before it enters the

pond. This area or strip should be as wide as or somewhat wider than the pond and 100 feet or more long.

After you prepare a seedbed, fertilize, and seed the

area to an appropriate mix of grasses and forbs. As the

water flows through the vegetation, the silt settles out

and the water entering the pond is relatively silt free.

Planning the pond

Although excavated ponds can be built to almost any

shape desired, a rectangle is commonly used in relatively flat terrain. The rectangular shape is popular

because it is simple to build and can be adapted to all

kinds of excavating equipment.

Rectangular ponds should not be constructed, however, where the resulting shape would be in sharp

contrast to surrounding topography and landscape

patterns. A pond can be excavated in a rectangular

form and the edge shaped later with a blade scraper to

create an irregular configuration (fig. 34).

The capacity of an excavated pond fed by surface

runoff is determined largely by the purpose or purposes for which water is needed and by the amount of

inflow that can be expected in a given period. The

required capacity of an excavated pond fed by an

underground waterbearing layer is difficult to determine because the rate of inflow into the pond can

seldom be estimated accurately. For this reason, the

pond should be built so that it can be enlarged if the

original capacity proves inadequate.

Figure 34 Geometric excavation graded to create more

natural configuration

Excavated area Final edge
59

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Selecting the dimensions—The dimensions selected

for an excavated pond depend on the required capacity. Of the three dimensions of a pond, the most important is depth. All excavated ponds should have a depth

equal to or greater than the minimum required for the

specific location. If an excavated pond is fed from

ground water, it should be deep enough to reach well

into the waterbearing material. The maximum depth is

generally determined by the kind of material excavated and the type of equipment used.

The type and size of the excavating equipment can

limit the width of an excavated pond. For example, if a

dragline excavator is used, the length of the boom

usually determines the maximum width of excavation

that can be made with proper placement of the waste

material.

The minimum length of the pond is determined by the

required pond capacity.

To prevent sloughing, the side slopes of the pond are

generally no steeper than the natural angle of repose

of the material being excavated. This angle varies with

different soils, but for most ponds the side slopes are

1:1 or flatter (fig. 35).

If the pond is to be used for watering livestock, provide a ramp with a flat slope (4:1 or flatter) for access.

Regardless of the intended use of the water, these flat

slopes are necessary if certain types of excavating

equipment are used. Tractor-pulled wheeled scrapers

and bulldozers require a flat slope to move material

from the bottom of the excavation.

Estimating the volume—After you have selected the

dimensions and side slopes of the pond, estimate the

volume of excavation required. This estimate determines the cost of the pond and is a basis for inviting

bids and for making payment if the work is to be done

by a contractor.

The volume of excavation required can be estimated

with enough accuracy by using the prismoidal formula:

V

A BC D = ( ) + +

×

4

6 27 [Eq. 6]

where:

V = volume of excavation (yd3)

A = area of the excavation at the ground

surface (ft2)

B = area of the excavation at the mid-depth

(1/2 D) point (ft2)

C = area of the excavation at the bottom of the

pond (ft2)

D = average depth of the pond (ft2)

27 = factor converting cubic feet to cubic yards

Depth

12 ft Depth

12 ft

24 ft 24 ft Width 40 ft

Total width 88 ft

Total length 172 ft

64 ft

6 ft

6 ft

6 ft

6 ft 2:1

2:1

4:1

2:1

136 ft

A

B

C

A

B

C

24 ft 48 ft Length 100 ft

Longitudinal section

(not to scale)

Cross section

(not to scale)

Figure 35 Typical sections of an excavated pond
Ponds—Planning, Design, Construction

60

Agriculture Handbook 590

As an example, assume a pond with a depth, D, of 12

feet, a bottom width, W, of 40 feet, and a bottom

length, L, of 100 feet as shown in figure 35. The side

slope at the ramp end is 4:1, and the remaining slopes

are 2:1. The volume of excavation, V, is computed as

follows:

  ̃

A

B

C

A BC

=× =

= × ( ) =

=× =

( ) + + =

88 172 15 136

4 4 64 136 34 816

40 100 4 000

4 53 952

,

,

,

,

 V yd = ×=

53 952

6

12

27

3 996 3 , ,

If the normal water level in the pond is at the ground

surface, the volume of water that can be stored in the

pond is 3,996 cubic yards times 0.00061963, or 2.48

acre-feet. To convert to gallons, 3,996 cubic yards

multiplied by 201.97 equals 807,072 gallons. The

sample procedure is used to compute the volume of

water that can be stored in the pond if the normal

water level is below the ground surface. The value

assigned to the depth D is the actual depth of the

water in the pond rather than depth of excavation.

A summary of methods for estimating the volume of

an excavated pond is provided in appendix A. This

summary information is reprinted from NRCS (formerly SCS) Landscape Architecture Note No. 2, Landscape Design: Ponds, September 2, 1988.

Waste material—Plan the placement or disposal of

the material excavated from the pond in advance of

construction operations. Adequate placement prolongs

the useful life of the pond, improves its appearance,

and facilitates maintenance and establishment of

vegetation. The waste material can be stacked, spread,

or removed from the site as conditions, nature of the

material, and other circumstances warrant.

If you do not remove the waste material from the site,

place it so that its weight does not endanger the stability of the side slopes and rainfall does not wash the

material back into the pond. If you stack the material,

place it with side slopes no steeper than the natural

angle of repose of the soil. Do not stack waste material

in a geometric mound, but shape and spread it to

blend with natural landforms in the area. Because

many excavated ponds are in flat terrain, the waste

material may be the most conspicuous feature in the

landscape. Avoid interrupting the existing horizon line

with the top of the waste mound (fig. 36).

Figure 36 Correct disposal of waste material

Then

A =× = 88 172 15 136 ,

C =× = 40 100 4 000 ,

( ) A BC + + 4 53 952 =

,

,

 

 





Not this

This

Waste material properly shaped,

graded, and vegetated blends

into surrounding landscape.

Waste material poorly shaped,

unvegetated, and interrupting the

horizon line appears unnatural.

yd3
61

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Waste material can also be located and designed to be

functional. It can screen undesirable views, buffer

noise and wind, or improve the site’s suitability for

recreation (fig. 37). In shaping the material, the toe of

the fill must be at least 12 feet from the edge of the

pond. In the Great Plains you can place the waste

material on the windward side of the pond to serve as

a snow fence for collecting drifts in the pond. These

banks can also reduce evaporation losses by breaking

the force of prevailing winds across the pond.

Perhaps the most satisfactory method of handling

waste material is to remove it from the site. Complete

removal, however, is expensive and can seldom be

justified unless the material is needed nearby. Waste

material can sometimes be used advantageously for

filling nearby low areas in a field or in building farm

roads. If state or county highway maintenance crews

need such material, you may be able to have them

remove it.

Building the pond

Clear the pond area of all undesired vegetation. Mark

the outside limits of the proposed excavation with

stakes. On the stakes indicate the depth of cut from

the ground surface to the pond bottom.

Excavation and placement of the waste material are

the principal items of work in building this type pond.

The kind of excavating equipment used depends on

the climatic and physical conditions at the site and on

what equipment is available.

In low-rainfall areas where water is unlikely to accumulate in the excavation, you can use almost any kind

of available equipment. Tractor-pulled wheeled scrapers, dragline excavators, and track-type tractors

equipped with a bulldozer blade are generally used.

Bulldozers can only push the excavated material, not

carry it; if the length of push is long, using these machines is expensive.

In high-rainfall areas and in areas where the water

table is within the limits of excavation, a dragline

excavator is commonly used because it is the only

kind of equipment that operates satisfactorily in any

appreciable depth of water. For ponds fed by ground

water aquifers, a dragline is normally used to excavate

the basic pond.

Excavate and place the waste material as close as

possible to the lines and grades staked on the site. If

you use a dragline excavator, you generally need other

kinds of equipment to stack or spread the waste material and shape the edge to an irregular configuration.

Bulldozers are most commonly used. Graders, either

tractor-pulled or self-propelled, can be used to good

advantage, particularly if the waste material is to be

shaped.

Figure 37 Waste material and plantings separate the pond from a major highway













New plantings

Waste material
Ponds—Planning, Design, Construction

62

Agriculture Handbook 590

Sealing the pond

Excessive seepage in ponds is generally because the

site is poor; that is, one where the soils in the impounding area are too permeable to hold water. Selecting a poor site is often the result of inadequate site

investigations and could have been avoided. In some

places no satisfactory site is available, but the need for

water is great enough to justify using a site that is

somewhat less than satisfactory. In this case the

original pond design must include plans for reducing

seepage by sealing (fig. 38). In some places excessive

removal of the soil mantle during construction, usually

to provide material for the embankment, exposes

highly pervious material, such as sand, gravel, or rock

containing cracks, crevices, or channels. This can be

avoided by carefully selecting the source of embankment material.

To prevent excessive seepage, reduce the permeability

of the soils to a point at which losses are insignificant

or at least tolerable. The method depends largely on

the proportions of coarse-grained sand and gravel and

of fine-grained clay and silt in the soil.

Compaction

Some pond areas can be made relatively impervious by

compaction alone if the material contains a wide range

of particle sizes (small gravel or coarse sand to fine

sand) and enough clay (10 percent or more) and silt to

effect a seal. This is the least expensive method of

those presented in this handbook. Its use, however, is

limited to these soil conditions as well as by the depth

of water to be impounded.

The procedure is simple. Clear the pond area of all

trees and other vegetation. Fill all stump holes, crevices, and similar areas with impervious material.

Scarify the soil to a depth of 16 to 18 inches with a

disk, rototiller, pulverizer, or similar equipment. Remove all rocks and tree roots. Roll the loosened soil

under optimum moisture conditions in a dense, tight

layer with four to six passes of a sheepsfoot roller in

the same manner as for compacting earth embankments.

Make the compacted seal no less than 12 inches thick

where less than 10 feet of water is to be impounded.

Because seepage losses vary directly with the depth of

water impounded over an area, increase the thickness

of the compacted seal proportionately if the depth of

Figure 38 Disking in chemical additive to seal a pond
63

Agriculture Handbook 590 Ponds—Planning, Design, Construction

water impounded exceeds 10 feet or more. The thickness of the compacted seal can be determined using

equation 7.

d k H

v k = ×

( ) − [Eq. 7]

where:

d = thickness of compacted seal

k = coefficient of permeability of compacted

seal, which is assumed to be 0.003 fpd

unless testing is done

H = water depth

v = allowable specific discharge which is

assumed to be 0.028 fpd unless otherwise

specified

As an example, assume a pond with a depth, H, of 12

feet. No soil samples were taken for laboratory testing.

Therefore, use the assumed values for k and v. Calculate the required minimum thickness of the compacted

seal. Using the preceding equation:

 d fpd ft

fpd fpd = ×−

0 003 12

0 028 0 003

.

. .

= 1.4 ft

If soil samples were taken and permeability tests were

performed on the material of the compacted seal at

the density it is to be placed, a thickness less than

what was calculated may be possible. Without knowing whether the soil underlying the compacted layer

will act as a filter for the compacted layer, the minimum thickness should never be less than 12 inches.

Compact the soils in two or more layers not exceeding

9 inches uncompacted over the area. Remove and

stockpile the top layer or layers while the bottom layer

is being compacted.

Clay blankets

Pond areas containing high percentages of coarsegrained soils, but lacking enough clay to prevent

excessive seepage, can be sealed by blanketing. Blanket the entire area over which water is to be impounded as well as the upstream slope of the embankment. The blanket should consist of a well-graded

material containing at least 20 percent clay. The requirements for good blanket material are about the

same as those described for earth embankments. You

can usually obtain material for the blanket from a

borrow area close enough to the pond to permit hauling at a reasonable cost.

Thickness of the blanket depends on the depth of

water to be impounded. The minimum compacted

thickness is 12 inches for all depths of water under 10

feet. Increase this thickness by 2 inches for each foot

of water over 10 feet and above.

Construction is similar to that for earth embankments.

Remove all trees and other vegetation and fill all holes

and crevices before hauling earth material from the

borrow area to the pond site in tractor-pulled wheeled

scrapers or similar equipment. Spread the material

uniformly over the area in layers 6 to 8 inches thick.

Compact each layer thoroughly, under optimum moisture conditions, by four to six passes of a sheepsfoot

roller before placing the next layer.

Protect clay blankets against cracking that results

from drying and against rupture caused by freezing

and thawing. Spread a cover of gravel 12 to 16 inches

thick over the blanket below the anticipated high

water level. Use rock riprap or other suitable material

to protect areas where the waterflow into the pond is

concentrated.

Bentonite

Adding bentonite is another method of reducing excessive seepage in soils containing high percentages of

coarse-grained particles and not enough clay. Bentonite is a fine-textured colloidal clay. When wet it

absorbs several times its own weight of water and, at

complete saturation, swells as much as 8 to 20 times

its original volume. Mixed in the correct proportions

with well-graded coarse-grained material, thoroughly

compacted and then saturated, the particles of bentonite swell until they fill the pores to the point that the

mixture is nearly impervious to water. On drying,

however, bentonite returns to its original volume

leaving cracks. For this reason, sealing with bentonite

usually is not recommended for ponds in which the

water level is expected to fluctuate widely. A laboratory analysis of the pond area material to determine

the rate of application is essential.
Ponds—Planning, Design, Construction

64

Agriculture Handbook 590

Before selecting this method of sealing a pond, locate

the nearest satisfactory source of bentonite and investigate the freight rates. If the source is far from the

pond site, the cost may prohibit the use of bentonite.

As with other methods, clear the pond area of all

vegetation. Fill all holes or crevices, and cover and

compact areas of exposed gravel with suitable fill

material.

The soil moisture level in the area to be treated is

important. Investigate it before applying bentonite.

The moisture level should be optimum for good compaction. If the area is too wet, postpone sealing until

moisture conditions are satisfactory. If it is too dry,

add water by sprinkling.

Spread the bentonite carefully and uniformly over the

area to be treated at the rate determined by the laboratory analysis. This rate usually is 1 to 3 pounds per

square foot of area. Thoroughly mix the bentonite with

the surface soil to a depth that will result in a 6-inch

compacted layer. This generally is an uncompacted

thickness of approximately 8 to 9 inches. A rototiller is

best for this operation, but a disk or similar equipment

can be used. Then compact the area with four to six

passes of a sheepsfoot roller.

If considerable time elapses between applying the

bentonite and filling the pond, protecting the treated

area against drying and cracking may be necessary. A

mulch of straw or hay pinned to the surface by the

final passes of the sheepsfoot roller gives this protection. Use rock riprap or other suitable material to

protect areas where water inflow into the treated area

is concentrated.

Chemical additives

Because of the structure or arrangement of the clay

particles, seepage is often excessive in fine-grained

clay soils. If these particles are arranged at random

with end-to-plate or end-to-end contacts, they form an

open, porous, or honeycomb structure; the soil is said

to be aggregated. Applying small amounts of certain

chemicals to these porous aggregates may result in

collapse of the open structure and rearrangement of

the clay particles. This dispersed structure reduces

soil permeability. The chemicals used are called dispersing agents.

The soils in the pond area should contain more than 50

percent fine-grained material (silt and clay) and at

least 15 percent clay for chemical treatment to be

effective. Chemical treatment is not effective in

coarse-grained soils.

Although many soluble salts are dispersing agents,

sodium polyphosphates and sodium chloride (common salt) are most commonly used. Of the sodium

polyphosphates, tetrasodium pyrophosphate and

sodium tripolyphosphate are most effective. Soda ash,

technical grade 99 to 100 percent sodium carbonate,

can also be used. Sodium polyphosphates generally

are applied at a rate of 0.05 to 0.10 pound per square

foot, and sodium chloride at a rate of 0.20 to 0.33 pound

per square foot. Soda ash is applied at a rate of 0.10 to

0.20 pound per square foot. A laboratory analysis of

the soil in the pond area is essential to determine

which dispersing agent will be most effective and to

determine the rate at which it should be applied.

Mix the dispersing agent with the surface soil and then

compact it to form a blanket. Thickness of the blanket

depends on the depth of water to be impounded. For

water less than 10 feet deep, the compacted blanket

should be at least 12 inches thick. For greater depths,

the thickness should be increased at the rate of 2 inches

per foot of water depth from 10 feet and above.

The soil moisture level in the area to be treated should

be near the optimum level for good compaction. If the

soil is too wet, postpone treatment. Polyphosphates release water from soil, and the material may become too

wet to handle. If the soil is too dry, add water by sprinkling.

Clear the area to be treated of all vegetation and trash.

Cover rock outcrops and other exposed areas of

highly permeable material with 2 to 3 feet of finegrained material. Thoroughly compact this material. In

cavernous limestone areas, the success or failure of

the seal may depend on the thickness and compaction

of this initial blanket.

Apply the dispersing agent uniformly over the pond

area at a rate determined by laboratory analysis. It can

be applied with a seeder, drill, fertilizer spreader, or by

hand broadcasting. The dispersant should be finely

granular, with at least 95 percent passing a No. 30

sieve and less than 5 percent passing a No. 100 sieve.
65

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Thoroughly mix the dispersing agent into each 6-inch

layer to be treated. You can use a disk, rototiller,

pulverizer, or similar equipment. Operating the mixing

equipment in two directions produces best results.

Thoroughly compact each chemically treated layer

with four to six passes of a sheepsfoot roller.

Protect the treated blanket against puncturing by

livestock. Cover the area near the high-water line with

a 12- to 18-inch blanket of gravel or other suitable

material to protect it against erosion. Use riprap or

other suitable material in areas where inflow into the

pond is concentrated.

Waterproof linings

Using waterproof linings is another method of reducing excessive seepage in both coarse-grained and finegrained soils. Polyethylene, vinyl, butyl-rubber membranes, and asphalt-sealed fabric liners are gaining

wide acceptance as linings for ponds because they

virtually eliminate seepage if properly installed.

Thin films of these materials are structurally weak, but

if not broken or punctured they are almost completely

watertight. Black polyethylene films are less expensive

and have better aging properties than vinyl. Vinyl, on

the other hand, is more resistant to impact damage

and is readily seamed and patched with a solvent

cement. Polyethylene can be joined or patched with a

special cement.

All plastic membranes should have a cover of earth or

earth and gravel not less than 6 inches thick to protect

against punctures. Butyl-rubber membranes need not

be covered except in areas traveled by livestock. In

these areas a minimum 9-inch cover should be used on

all types of flexible membranes. The bottom 3 inches

of cover should be no coarser than silty sand.

Clear the pond area of all undesired vegetation. Fill all

holes and remove roots, sharp stones, or other objects

that might puncture the film. If the material is stony or

of very coarse texture, cover it with a cushion layer of

fine-textured material before placing the lining.

Some plants may penetrate both vinyl and polyethylene film. If nutgrass, johnsongrass, quackgrass, and

other plants having high penetration are present, the

subgrade, especially the side slopes, should be sterilized. Several good chemical sterilizers are available

commercially. Sterilization is not required for covered

butyl-rubber linings 20 to 30 mils thick.

Lay the linings in sections or strips, allowing a 6-inch

overlap for seaming. Vinyl and butyl-rubber linings

should be smooth, but slack. Polyethylene should have

up to 10 percent slack. Be extremely careful to avoid

punctures. Anchor the top of the lining by burying it in

a trench dug completely around the pond at or above

the normal water level. The anchor trench should be 8

to 10 inches deep and about 12 inches wide.
Ponds—Planning, Design, Construction

66

Agriculture Handbook 590

Establishing vegetation

Trees, shrubs, grasses, and forbs should be planted

during or soon after construction. Their functions

include erosion control, screening, space definition,

climate control, and wildlife habitat. The vegetation

should be able to survive under prevailing conditions

with minimum maintenance. Native varieties are

preferred for new plantings.

In many areas the exposed surface of the dam, the

auxiliary spillway, and the borrow areas as well as

other disturbed surfaces can be protected from erosion by establishing a vegetative community of appropriate species. Prepare a seedbed as soon after construction as practicable. This is generally done by

disking or harrowing. Fertilize and seed with mixtures

of perennial grasses and forbs appropriate for local

soil and climatic conditions. If construction is completed when the soils are too dry for the seeds to

germinate, irrigate the soils to ensure prompt germination and continued growth. Mulching with a thin layer

of straw, fodder, old hay, asphalt, or one of several

commercially manufactured materials may be desirable. Mulching not only protects the newly prepared

seedbed, seeds, or small plants from rainfall damage,

but also conserves moisture and provides conditions

favorable for germination and growth.

Soil bioengineering systems should be employed to

establish woody vegetation where appropriate on the

shorelines of ponds. The systems best suited to these

conditions include live stakes, live fascines,

brushmattresses, live siltation, and reed clumps.

Additional information about these and other soil

bioengineering systems is in Part 650, Engineering

Field Handbook, chapters 16 and 18.

Trees and shrubs that remain or those planted along

the shoreline will be subject to flooding, wave action,

or a high water table. The ability to tolerate such

drastic changes varies greatly among species. Flood

tolerance and resistance to wave action depend on

root density and the ability to regenerate from exposed roots.

A planting plan indicating the species and rate of

application of the vegetation can be helpful in achieving the desired results. For information on recommended plants and grass mixtures, rates of fertilization, and mulching procedures, contact the local

representatives of the Natural Resources Conservation

Service or the county agent.

Protecting the pond

Construction of the pond is not complete until you

have provided protection against erosion, wave action,

trampling by livestock, and any other source of damage. Ponds without this protection may be short lived,

and the cost of maintenance is usually high.

Leave borrow pits in condition to be planted so that

the land can be used for grazing or some other purpose. Grade and shape the banks or side slopes of

borrow pits to a slope that permits easy mowing,

preferably no steeper than 4:1, and allows the graded

area to blend with the landscape. It is often desirable

to establish vegetation to make the borrow area compatible with undisturbed surroundings.

Grade all areas or pits from which borrow material has

been obtained so they are well drained and do not

permit stagnant water to accumulate as breeding

places for mosquitoes.

Wave action

Several methods are available to protect the upstream

face of a dam against wave action. The choice of

method depends on whether the normal pool level

remains fairly constant or fluctuates. An irrigation

pond is an example of the latter. In these ponds, water

is withdrawn periodically during the growing season

and the water level may fluctuate from normal pool

level to near pond bottom one or more times each

year. The degree of protection required also influences

the choice of method.

Berms—If the water level in the pond is expected to

remain fairly constant, a berm 6 to 10 feet wide located at normal pool level generally provides adequate

protection against wave action. The berm should have

a downward slope of about 6 to 12 inches toward the

pond. The slope above the berm should be protected

by vegetation.
67

Agriculture Handbook 590 Ponds—Planning, Design, Construction

Booms—Log booms also break up wave action. A

boom consists of a single or double line of logs

chained or cabled together and anchored to each end

of the dam. Tie the logs end to end as close together as

practicable. Leave enough slack in the line to allow the

boom to adjust to fluctuating water levels. If you use

double rows of logs, frame them together to act as a

unit. For best results place the boom so that it floats

about 6 feet upstream from the face of the dam. If the

dam is built on a curve, you may need anchor posts on

the face of the dam as well as at the ends to keep the

boom from riding on the slope. Booms do not give as

much protection as some other methods described,

but they are inexpensive if timber is readily available.

They generally are satisfactory for small structures.

Riprap—Rock riprap is an effective method of control

if a high degree of protection is required or if the water

level fluctuates widely. Riprap should extend from the

top of the dam down the upstream face to a level at

least 3 feet below the lowest anticipated water level.

Riprap is dumped directly from trucks or other vehicles or is placed by hand. Hand placing gives more

effective protection and requires less stone. Dumping

requires more stone, but less labor. The layer of stones

should be at least 12 inches thick and must be placed

on a bed of gravel or crushed stone at least 10 inches

thick. This bed keeps the waves from washing out the

underlying embankment material that supports the riprap.

If riprap is not continuous to the upstream toe, provide

a berm on the upstream face to support the layer of

riprap and to keep it from sliding downslope. If possible, use stones whose color is similar to that in the

immediate area. Allow grass and herbs to grow

through the riprap to blend with surrounding vegetation, but control woody vegetation.

Livestock

Complete fencing of areas on which embankment

ponds are built is recommended if livestock are grazed

or fed in adjacent fields. Fencing provides the protection needed to develop and maintain a good plant

cover on the dam, the auxiliary spillway, and in other

areas. It enhances clean drinking water and eliminates

damage or pollution by livestock. If you fence the

entire area around the pond and use the pond for

watering livestock, install a gravity-fed watering

trough just downstream from the dam and outside the

fenced area.

Fencing also enables you to establish an environment

beneficial to wildlife. The marshy vegetation needed

around ponds for satisfactory wildlife food and cover

does not tolerate much trampling or grazing.

Not all ponds used for watering livestock need to be

fenced. On some western and midwestern ranges, the

advantages derived from fencing are more than offset

by the increased cost and maintenance and the fact

that fewer animals can water at one time. A rancher

with many widely scattered ponds and extensive

holdings must have simple installations that require

minimum upkeep and inspection. Fencing critical

parts of livestock watering ponds, particularly the

earthfill and the auxiliary spillway, is usually advantageous even if complete fencing is impractical.
Ponds—Planning, Design, Construction

68

Agriculture Handbook 590

Operating and maintaining

the pond

A pond, no matter how well planned and built, must be

adequately maintained if its intended purposes are to

be realized throughout its expected life. Lack of operation and maintenance has caused severe damage to

many dams and spillways. Some structures have failed

completely. For these reasons you must be fully aware

of the need for adequate operation and maintenance,

and you should carry out all measures required.

Inspect your pond periodically. Be sure to examine it

after heavy rains to determine whether it is functioning properly or needs minor repairs. Repairing damage

immediately generally eliminates the need for more

costly repairs later. Damage may be small, but if neglected it may increase until repair becomes impractical and the entire structure must be replaced.

Fill any rills on the side slopes of the dam and any

washes in the auxiliary spillway immediately with

suitable material and compact it thoroughly. Fertilize

as needed and reseed or resod these areas. If the

upstream face of the earthfill shows signs of serious

washing or sloughing because of wave action, install

protective devices, such as booms or riprap. If seepage

through or under the dam is evident, consult an engineer at once so that you can take proper corrective

measures before serious damage occurs.

To maintain the protective plant cover on the dam and

on the auxiliary spillway, mow it frequently and fertilize when needed. Mowing prevents the growth of

woody plants where undesirable and helps develop a

cover and root system more resistant to runoff. If the

plant cover is protected by fencing, keep the fences in

good repair.

Keep pipes, trash racks, outlet structures, valves, and

watering troughs free of trash at all times.

In some localities burrowing animals such as badgers,

gophers, beaver, and prairie dogs cause severe damage

to dams or spillways. If this damage is not repaired, it

may lead to failure of the dam. Using a submerged

inlet or locating the inlet in deeper water discourages

beavers from the pipe inlets. A heavy layer of sand or

gravel on the fill discourages burrowing to some

extent. Poultry netting can be used, but in time it rusts

out and needs to be replaced.

Keep the water in your pond as clean and unpolluted

as possible. Do not permit unnecessary trampling by

livestock, particularly hogs. If fencing is not practical,

pave the approaches to the pond with small rocks or

gravel. Divert drainage from barn lots, feeding yards,

bedding grounds, or any other source of contamination away from the pond. Clean water is especially

important in ponds used for wildlife, recreation, and

water supply.

In areas where surface water encourages mosquito

breeding, stock the pond with topfeeding fish. Gambusia minnows are particularly effective in controlling

mosquitoes. In malaria areas, do not keep any aquatic

growth or shoreline vegetation and take special precautions in planning, building, and operating and

maintaining the pond. Most states in malaria areas

have health regulations covering these precautions.

These regulations should be followed.

In some areas, algae and other forms of plant life may

become objectionable. They can cause disagreeable

tastes or odors, encourage bacterial development, and

produce an unsightly appearance.
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Agriculture Handbook 590 Ponds—Planning, Design, Construction

Pond safety

Ponds, like any body of water, attract people so that

there is always a chance of injury or drowning. You

may be planning to build a pond for watering livestock, irrigation, or any of the other purposes discussed in this handbook. However, your family and

friends may picnic beside the pond or use it for fishing, swimming, boating, or ice skating, and you can

never tell what a small child passing by may do.

Your pond can become a source of pleasure as well as

profit, but only if it is safe. You can take some of the

following steps to prevent injuries or drownings and to

protect yourself financially.

Before construction

Almost all states have laws on impounding water and

on the design, construction, and operation and maintenance of ponds. In many states small farm ponds are

exempt from any such laws. You should become

familiar with those that apply in your state and be sure

that you and your engineer comply with them.

Find out what your community or state laws are

regarding your liability in case of injury or death

resulting from use of your pond, whether you authorize such use or not. This is particularly important if

you intend to open your pond to the public and charge

a fee for its use. You may find that you need to protect

yourself with insurance.

You should decide how the water is going to be used

so that you can plan the needed safety measures

before construction starts. For example, if the water is

to be used for swimming, guards over conduits are

required. You may wish to provide for beaches and

diving facilities; the latter require a minimum depth of

about 10 feet of water.

During construction

Your contractor should take other safety measures

during pond construction. Remove all undesirable

trees, stumps, and brush and all rubbish, wire, junk

machinery, and fences that might be hazardous to

boating and swimming. Eliminate sudden dropoffs and

deep holes.

After completion

Mark safe swimming areas and place warning signs at

all danger points. Place lifesaving devices, such as ring

buoys, ropes, planks, or long poles, at swimming areas

to facilitate rescue operations should the need arise.

Place long planks or ladders at ice skating areas for

the same reason.
Ponds—Planning, Design, Construction

70

Agriculture Handbook 590

References

U.S. Department of Agriculture, Soil Conservation

Service. 1984. Engineering Field Manual.

Washington, DC.

U.S. Department of the Army, Corps of Engineers.

Technical Report E-79-2, Root tolerance of

plants: A state-of-the-art review.

U.S. Department of Agriculture, Soil Conservation

Service. 1988. Landscape Design: Ponds, Landscape Architecture Note 2. Washington, DC.

Van Dersal, William R. 1938. Native Woody Plants of

the United States. Miscellaneous Publication 303.

U.S. Department of Agriculture. Washington, DC.
71

Agriculture Handbook 590 Ponds—Planning, Design, Construction Glossary

abutment A portion of a valley cross section higher in elevation than the valley floor.

The slope above the valley floor.

antiseep collar A constructed barrier installed perpendicular to a pipe or conduit and

usually made of the same material as the pipe or conduit. Its purpose is to

intercept the flow of seepage along the pipe or conduit and to make the

seepage path longer.

appurtenance Interrelated elements or components of a designed system, or structure.

auxiliary spillway The spillway designed to convey excess water through, over, or around a

dam.

backslope The downstream slope of an embankment.

bench mark Point of known elevation for a survey. May be in relation to National Geodetic Vertical Datum (NGVD) or assumed for a given project.

berm A strip of earth, usually level, in a dam cross section. It may be located in

either the upstream side slope, downstream side slope, or both.

boom A floating barrier extending across a reservoir area, just upstream from the

dam, to protect the side slope from erosion.

borrow area An area from which earthfill materials can be taken to construct the dam.

bottom width A flat, level cross section element normally in an open channel, spillway, or

trench.

coefficient The rate of flow of a fluid through a unit cross section of a porous mass

of permeability under a unit hydraulic gradient.

compaction The process by which the soil grains are rearranged to decrease void space

and bring them into closer contact with one another, thereby increasing the

weight of solid material per cubic foot.

conduit (pipe) Any channel intended for the conveyance of water, whether open or closed.

control section A part of an open channel spillway where accelerated flow passes through

critical depth.

core trench The trench in the foundation material under an earth embankment or dam

(excavation) in which special material is placed to reduce seepage.

of a trench)

critical depth Depth of flow in a channel at which specific energy is a minimum for a

given discharge.

cross section A section formed by a plane cutting an area, usually at right angles to an axis.
Ponds—Planning, Design, Construction

72

Agriculture Handbook 590

dam (earth dam) A constructed barrier, together with any associated spillways and appurtenant works, across a watercourse or natural drainage area, which permanently impounds and stores water, traps sediment, and/or controls flood

water.

design elevation The height above a defined datum describing the required elevation of pool

that will provide the required temporary storage.

diaphragm See Antiseep collar.

drain An appurtenance installed in the dam and/or its foundation to safely collect

and discharge seepage water.

drawings A graphical representation of the planned details of the work of improvements.

drop inlet A vertical entrance joined to a barrel section of a principal spillway system.

earthfill Soil, sand, gravel, or rock construction materials used to build a dam and its

components.

effective The difference in elevation in feet between the lowest auxiliary spillway

 fill height crest and the lowest point in the original cross section on the centerline of

the dam. If there is no auxiliary spillway, the top of the dam becomes the

upper limit.

embankment A structure of earth, gravel, or similar material raised to form a dam.

excavated pond A reservoir constructed mainly by excavation in flat terrain. A relatively

short embankment section on the downstream watercourse side may be

necessary for desired storage amount.

exit channel The portion downstream from the control section that conducts the flow to

 (of an open a point where it may be released without jeopardizing the dam.

 channel spillway)

fill height The difference in elevation between the existing ground line and the proposed top of dam elevation, including allowance for settlement.

filter and drainage A soil piping and water seepage control device installed perpendicular to a

 diaphragm pipe or conduit, consisting of a single, or multizones of, aggregate. Its

purpose is to intercept the water flow along pipes or conduits and prevent

the movement of soil particles that makeup the embankment.

flow depth The depth of water in the auxiliary spillway or any other channel.

foundation The surface upon which a dam is constructed.

freeboard The difference in elevation between the minimum settled elevation of the

top of dam and the highest elevation of expected depth of flow through the

auxiliary spillway.
73

Agriculture Handbook 590 Ponds—Planning, Design, Construction

hooded or A fabricated assembly attached to the principal spillway pipe to improve

 canopy inlet the hydraulic efficiency of the overall pipe system.

inlet section The portion upstream from the control section.

 (of an open

 channel spillway)

mulch A natural or artificial layer of plant residue or other material, such as grain

straw or paper, on the soil surface.

outlet channel A section of open channel downstream from all works of improvement.

outlet section The downstream portion of an open channel or of a principal spillway.

peak discharge The maximum flow rate at which runoff from a drainage area discharges

past a specific point.

pond A still body of water of limited size either naturally or artificially confined

and usually smaller than a lake.

pool area The location for storing water upstream from the dam.

principal spillway The lowest ungated spillway designed to convey water from the reservoir at

predetermined release rates.

profile A representation of an object or structure seen from the side along its

length.

propped outlet A structural support to protect the outlet section of a pipe principal spillway.

riprap A loose assemblage of broken stones commonly placed on the earth surface

to protect it from the erosive forces of moving water or wave action.

riser The vertical portion of a drop inlet.

sealing The process used to close openings in soil materials and prevent seepage of

water.

sediment Solid material, both mineral and organic, that is being transported in suspension, or has been moved from its site of origin by water, air, gravity, or

ice and has come to rest on the Earth’s surface either above or below the

principal spillway crest.

settlement Movement of an embankment or structure during the application of loads.

side slope (ratio) The ratio of horizontal to vertical distance measured along the slope, either

on an open channel bank or on the face of an embankment, usually expressed in “n”:1; e.g., 2:1 (meaning two units horizontal to one unit vertical).

site investigation Site visit to evaluate physical features of a proposed project or watershed

including soils data and characteristics of the watershed.
Ponds—Planning, Design, Construction

74

Agriculture Handbook 590

specifications Detailed statements prescribing standards, materials, dimensions, and

workmanship for works of improvement.

specific discharge The theorical flow rate through the full flow cross sectional area of a porous media.

spillway An open or closed channel, conduit or drop structure used to convey water

from a reservoir. It may contain gates, either manually or automatically

controlled, to regulate the discharge of water.

stage The elevation of a water surface above its minimum plane or datum of

reference.

storage volume The total volume available from the bottom of the reservoir to the top of

dam.

temporary storage The volume from the crest of the principal spillway to the top of dam.

top width The horizontal dimension (planned or existing) across the top of dam,

perpendicular to the centerline.

valley floor Part of a valley cross section that is level or gently sloping.

vegetative The amount of hindrance to flow caused by the type, density, and height

 retardance of vegetation.

visual focus An element in the landscape upon which the eyes automatically focus

because of the element’s size, form, color, or texture contrast with its

surroundings.
75

Agriculture Handbook 590 Ponds — Planning, Design, Construction

The volume of a pond can be estimated by using the

prismoidal formula:

V

A BC D = ( ) + +

×

4

6 27

A

A

B

C

D

B

C

V = volume of excavation (yd3)

A = area of excavation at ground level (ft2)

B = area of excavation at the middle depth of

the pond (ft2)

C = area of excavation at the bottom of the

pond (ft2)

D = average depth of the pond in (ft)

27 = factor converting cubic feet to cubic yards

Note: When using meters for area and depth, 27 is not

needed. The formula would then be:

V

A BC = D ( ) + +

×

4

6

where:

V = volume of excavation (m3)

This formula can be used for ponds of any shape. The

area of excavation can be determined either by

planimetering the shape on the plans or by using

geometric formulas for areas. The following formulas

give the area of some common shapes.

Rectangle:

l

w Rectangle A = wl

Circle:

r

Circle A or = πr r 2 2 3 14 .

Quadrant:

r

Quadrant A or = ( ) π

4

0 7854 2 2 rr r .

Parabola:

h

s

Parabola A = 0 67 . sh

Ellipse:

w

l

Ellipse A or = π

4

wl wl 0 7854 .

Appendix A Estimating the Volume of an

Excavated Pond
Ponds — Planning, Design, Construction

76

Agriculture Handbook 590

Example A–1 Determing the volume of an elliptical pond

As an example, determine the volume of an elliptical

pond with a major axis (l) of 160 ft, a minor axis (w)

of 90 ft at the surface, a depth (D) of 8 ft, and 2:1 side

slopes. Use the prismoidal formula:

V

A BC D = ( ) + +

×

4

6 27

160 in.

90 in. D

A

A

B

C

B

C

Step 1: Calculate the area of the surface (A) using the

formula,

Area for an ellipse = ( )

= × ( )

=

π

4

3 14

4

90 160

11 304 2

wl

A

A ft

.

,

Step 2: Determine the dimensions of the bottom (C).

Since the side slopes are 2:1 and depth is 8 feet, the

bottom will be 16 feet narrower than the surface. The

bottom dimensions would then be 58 feet (w) by 128

feet (I).

Step 3: Calculate the area of the bottom (C) using

C

C ft

= × ( )

=

3 14

4

58 128

5 828 2

.

,

Step 4: Determine the dimensions of the middle

depth (B). Since the middle depth lies equally between the surface and the bottom, the dimensions can

be determined by adding the surface and bottom

dimensions together and dividing by 2.

160 128

2

144

90 58

2

74

+ =

+ =

 (major axis)

 (minor axis)

Step 5: Calculate the area of the middle depth (B)

using Area = (pi) wl.

B

B ft

= × ( )

=

3 14

4

74 144

8 365 2

.

,

160 ft

1

2

8 ft

144 ft

128 ft

90 ft

1

2

8 ft

74 ft

58 ft

Step 6: Determine the volume in cubic yards.

V

V

V

= [ ] + × ( ) +×

= ×

=

11 304 4 8 365 5 828

6

8

27

50 592

6

8

27

2 498

, ,,

,

, or approx. 2,500 yd3 yd3
77

Agriculture Handbook 590 Ponds — Planning, Design, Construction

The area of the surface, the middle depth, and bottom

can also be determined by using a planimeter. In this

example, the pond was drawn at a 1 inch = 40 feet

scale and has a depth of 8 feet.

Step 1: Measure the surface area (A) using a planimeter. Convert the measurement from square inches into

square feet. (A factor of 1,600 is used to convert square

inches into square feet for a scale of 1 inch = 40 feet.)

A in ft = ×= 10 0 1 600 16 000 2 2 .,,

Step 2: Measure the middle depth (B) area and convert to square feet.

B in ft = ×= 7 7 1 600 12 320 2 2 . ,,

Step 3: Measure the bottom (C) and convert to square

feet.

C in ft = ×= 5 5 1 600 8 800 2 2 . ,,

Step 4: Use the prismoidal formula to estimate volume of excavation in cubic yards.

V

A BC

V

V

V yd

= ( ) + +×

= [ ] + × ( ) +

×

= ×

=

4

6

8

27

16 000 4 12 320 8 800

6

8

27

74 080

6

8

27

3 658 3

, ,,

,

,

Example A–2 Determining area of the surface, the middle depth, and bottom

ABC

Scale: 1 inch = 40 feet
Ponds — Planning, Design, Construction

78

Agriculture Handbook 590
79

Agriculture Handbook 590 Ponds — Planning, Design, Construction

The plant lists in tables B–1 through B–4 were taken

from the Corps of Engineers Technical Report E-79-2,

Flood Tolerance of Plants: A State-of-the-Art Review.

The ratings used are intended only to be a relative

classification. Tolerance will vary with local conditions. The plants are divided into four groups: very

tolerant, tolerant, somewhat tolerant, and intolerant.

Each plant was also given a range coinciding with the

plant growth regions, figure B–1, developed from

USDA Miscellaneous Publication 303, Native Woody

Plants of the United States, by William R. Van Dersal.

Flooding creates several conditions that are unfavorable to most woody species. The most critical condition appears to be the depletion of soil oxygen that is

critical to plants. The lack of oxygen favors anaerobic

bacteria, which can lead to the development of toxic

organic and inorganic byproducts. A plant’s ability to

survive flooding is dependent on many factors; among

them are flood depth, flood duration, flood timing, plant

age and size, wave action, and substrata composition.

Appendix B Flood-Tolerant Native Trees and

Shrubs
Ponds — Planning, Design, Construction

80

Agriculture Handbook 590

Figure B–1 Plant growth regions

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

North Pacific Coast

Willamette Valley–Puget Sound

Central California Valleys

Cascade–Sierra Nevada

Southern California

Columbia River Valley

Palouse–Bitterroot Valley

Snake River Plain–Utah Valley

Great Basin–Intermontane

Southwestern Desert

Southern Plateau

Northern Rocky Mountains

Central Rocky Mountains

Southern Rocky Mountains

Northern Great Plains

Central Great Plains

Southern Plains

18.

19.

20.

21.

22.

23.

24.

25.

26.

27.

28.

Northern Black Soils

Central Black Soils

Southern Black Soils

Northern Prairies

Central Prairies

Western Great Lakes

Central Great Lakes

Ozark–Ohio–Tennessee River Valley

Northern Great Lakes–St. Lawrence

Appalachian

Piedmont

29.

30.

31.

32.

Upper Coastal Plain

Swampy Coastal Plain

South–Central Florida

Subtropical Florida

12

9

8

13

13

12

7 7

2

2

4 1

6

8

9

13 

4

3

5

10

11 

14 

13

16

17

20

30

29

30

31

32

29

28

27

25

22

26

24

26

23

21

19

18

25

15

14 
81

Agriculture Handbook 590 Ponds — Planning, Design, Construction

Table B–1 Flood tolerance of very tolerant native plants

[These plants are able to survive deep, prolonged flooding for more than 1 year.]

Scientific name Common name Range

Carya aquatica Water hickory 20, 25, 28, 29, 30

C. illinoensis Pecan 16, 20, 22, 25, 29, 30

Cephalanthus occidentalis Buttonbush 3-5, 11, 16, 17, 19-30

Cornus stolonifera Redosier dogwood 4, 7-9, 11-15, 18, 21 -28

Forestiera acuminata Swamp privet 20, 22, 25, 29, 30

Fraxinus pennsylvanica Green ash 15, 18, 20-30

Gleditsia aquatica Waterlocust 20, 25, 28-30

Illex decidua Deciduous holly 16, 17, 20, 25, 28-30

Nyssa aquatica Water tupelo 25, 29, 30

Planera aquatica Water elm 20, 25, 29, 30

Quercus lyrata Overcup oak 20, 22, 25, 28-30

Salix exigua Narrow leaf willow 4-16

S. hookeriana Hooker willow 1

S. lasiandra Pacific willow 1-5, 11, 13, 14

S. nigra Black willow 16, 17, 19-30

Taxodium distichum Baldcypress 17, 20, 25, 28-32
Ponds — Planning, Design, Construction

82

Agriculture Handbook 590

Table B–2 Flood tolerance of tolerant native plants

[These plants are able to survive deep flooding for one growing season, with significant

mortality occurring if flooding is repeated the following year.]

Scientific name Common name Range

Acer negundo Boxelder 17-30

A. rubrum Red maple 19-30

A. saccharinum Silver maple 18-30

Alnus glutinosa Black alder 26-27

Amorpha fruticosa False indigo 5, 10, 11, 15-29

Betula nigra River birch 20, 22, 23, 25-29

Celtis occidentalis Hackberry 15, 16, 18, 20-30

Diospyros virginiana Persimmon 20, 22, 25, 27-31

Kalmia polifolia Bog laurel 4, 12, 23, 24, 26, 27

Ledum groenlandicum Labrador tea 4, 12, 23, 24, 26, 27

Liquidambar styraciflua Sweetgum 20, 22, 25, 27-30

Nyssa sylvatica Blackgum 20, 22, 24-30

Pinus contorta Lodgepole pine 2, 4, 10, 12-15

Platanus occidentalis Sycamore 16, 20-22, 24-30

Populus trichocarpa Black cottonwood 1-8, 12, 13

Quercus lyrata Overcup oak 20, 22, 25, 28-30

Q. palustris Pin oak 21-25, 27, 29

Sambucus callicarpa Pacific red elder 1,2,4

Spirea douglasii Hardhack 1-4

Tamarix gallica French tamarisk 3, 4, 9-11, 13, 16, 19, 22, 25, 29, 30

Thuja plicata Western redcedar 1, 2, 4, 6, 7, 12

Ulmus americana American elm 15, 16, 18-23, 25-30

Vaccinium uliginosum Blueberry 1, 4, 12-14, 23, 24, 26, 27
83

Agriculture Handbook 590 Ponds — Planning, Design, Construction

Table B–3 Flood tolerance of somewhat tolerant native plants

[These plants are able to survive flooding or saturated soils for 30 consecutive days during the growing season.]

Scientific name Common name Range

Alnus rugosa Hazel alder 20, 22-29

Carpinus caroliniana Ironwood 20-30

Celtis laevigata Sugarberry 11, 16, 17, 20, 22, 25, 29, 30

Cornus nuttallii Pacific dogwood 1-5

Crataegus mollis Downy hawthorn

Fraxinum americana White ash 20, 22-25, 27-30

Gleditsia triacanthos Honeylocust 16, 20, 22-27, 29, 30

Ilex opaca American holly 20, 25, 27-30

Juglans nigra Black walnut 18-30

Juniperus virginiana Eastern redcedar 18, 20-29

Malus spp. Apple

Morus rubra Red mulberry 16-25, 27-30

Ostrya virginiana Eastern hophornbeam 15, 18, 20-25, 27-30

Picea stichensis Sitka spruce 1

Pinus echinata Shortleaf pine 20, 25, 27-30

P. ponderosa Ponderosa pine 4

Populus grandidentata Bigtooth aspen 21-23, 25-28

Quercus alba White oak 20, 22-30

Q. bicolor Swamp white oak 21-28

Q. imbricaria Shingle oak 22-25, 27, 28

Q. macrocarpa Bur oak 15, 16, 18-30

Q. nigra Water oak 17, 20, 25, 28-30

Q. phellos Willow oak 20, 25, 27-30

Q. rubra Northern red oak 21 -27

Rhus glabra Smooth sumac 6-9, 11, 14, 15, 17-31

Tilia americana American basswood 20-27

Tsuga heterophylla Western hemlock 1 , 2, 4, 6, 12

Ulmus alata Winged elm 17, 20, 25, 28-30

U. rubra Red elm 25, 27, 29

Viburnum prunifolium Blackhaw 20, 22-25, 27-30
Ponds — Planning, Design, Construction

84

Agriculture Handbook 590

Table B–4 Flood tolerance of intolerant native plants

[These plants are unable to survive more than a few days of flooding during the growing

season without significant mortality.]

Scientific name Common name Range

Acer macrophyllum Bigleaf maple 1-5

A. saccharum Sugar maple 15, 18, 21-29

Alnus rubra Red alder 1 , 2, 5, 6

A. sinuata Sitka alder 2, 4, 6, 7, 12

Betula lutea Yellow birch 21-28

B. papyrifera Paper birch 12, 13, 15, 18, 21-24, 26, 27

B. populifolia White birch 24, 26-28

Buxus sempervirens Boxwood

Carya cordiformis Bitternut hickory 20, 22-30

C. laciniosa Shellbark hickory 22, 24, 25, 27, 28, 29

C. ovata Shagbark hickory 21-30

C. tomentosa Mockernut hickory 20, 22, 24, 25, 27-30

Cercis canadensis Eastern redbud 22-25, 27-30

Cornus florida Flowering dogwood 20, 22-25, 27-30

Corylus avellana Filbert

C. rostrata Hazel 15, 18, 21-29

Cotoneaster spp. Cotoneaster

Fagus grandifolia American beech 20, 22-30

Gymnocladus dioica Kentucky coffeetree 19, 21-25, 27

Ilex aquifolium Holly

Philadelphus gordonianus Mock orange 4, 6-8, 12

Picea abies Norway spruce

P. pungens Colorado spruce 9, 12, 13, 14

P. rubens Red spruce 27

Pinus strobus Eastern white pine 21-24, 27

P. taeda Loblolly pine 19, 20, 22, 25, 28-30

Populus tremuloides Quaking aspen 1, 2, 4, 6-9, 11, 15, 18, 21-27

Prunus americana Wild plum 12-25, 27-30

P. emarginata Bitter cherry 1, 2, 4, 6, 8-14

P. laurocerasus Cherry-laurel

P. serotina Black cherry 11, 18-30

Psuedotsuga menziesii Douglas fir

Pyrus rivularis Wild apple 1, 2, 4

Q. marilandica Blackjack oak 16,19, 20, 22, 24, 25, 27-30

Q. muehlenbergii Chinquapin oak 11, 16, 20-30

Q. shumardii Texas oak 16, 20, 22, 24, 25, 27-29

Q. stellata Post oak 19, 20, 22, 25, 27-30

Q. velutina Black oak 20, 22-30

Rhamnus purshinana Cascara 1-4, 6, 7, 9, 11, 12

Rubus procerus Blackberry
85

Agriculture Handbook 590 Ponds — Planning, Design, Construction

Table B–4 Flood tolerance of intolerant native plants—Continued.

[These plants are unable to survive more than a few days of flooding during the growing

season without significant mortality.]

Scientific name Common name Range

Sassafras albidum Sassafras 20, 22-30

Sorbus aucuparia Rowan tree 21, 22, 27

Symphoricarpos occidentalis Snowberry 15, 18, 21-24

Syringa vulgans Lilac

Thuja occidentalis American arborvitae 22-24, 26, 27

Tsuga canadensis Eastern hemlock 22-25, 27, 28