There are two basic types of ponds: embankment and excavation.

Embankment ponds are built by placing 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.

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

After you've decided the why of the pond, you need to consider the where. Selection of the pond site is one of the most important steps in construction. If possible, consider more than one location and then evaluate each one's economic, accessibility, and safety factors.

For economy, locate the pond where the largest storage volume can be obtained with the least amount of earthfill. Say, in a valley where a dam can be built across a narrow section where slopes are steep, and the slope of the valley floor permits a large area to be flooded.

	If the pond is to be used to water livestock, locate it 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.
If the pond water will have to be conveyed for use elsewhere, such as for irrigation or fire protection, locate the pond close to the major water use. Conveying water is expensive, so the shorter the distance, the better. Otherwise it may not be practical.

Ponds intended for recreational purposes, such as fishing, boating, and swimming, should be accessible. Income-producing ponds, used by the general public, must be easily reached by automobile.

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.

Consider the possibility of failure of the pond's dam and the damage that could result from the sudden release of water, such as loss of life, injury to persons or livestock, and damage to homes.

Be sure that no buried pipelines or cables cross the proposed pond site. If they do, you must notify the utility company before starting construction and obtain permission to excavate.

Other factors to consider:

Adequacy of the drainage area - For ponds where surface runoff is the main source of the water, the contributing drainage area must be large enough to maintain water in the pond during droughts. The physical characteristics that affect the amount of runoff are relief, soil infiltration, plant cover, and surface storage. Storm characteristics, such as amount, intensity, and duration of rainfall, obviously will also affect runoff.

Minimum pond depth - To avoid shortages of water, the water must be deep enough to meet the requirements of its intended use, and to offset probable seepage and evaporation losses. To estimate pond capacity, use this simple method:

Drainage area protection - To maintain the required depth and capacity of a pond, the inflow of water must be reasonably free of silt. Land under permanent cover of trees or vegetation provides the most desirable drainage area. For cultivated drainage areas, application and maintenance of erosion control practices is essential to their protection.

Landscape - To maximize visibility of the pond, locate it so that the major sight line crosses the longest dimension of water surface. This way the viewer will see the water before noticing the dam, pipe inlet, or spillway. Ponds designed around existing vegetation will help blend the pond into the surroundings. The vegetation will provide shade on hot days as well as habitat for wildlife.

You've got your location, and you're ready to build. What's next? It depends on the type of pond you are building.

Embankment Ponds

Before beginning construction of this type of pond, a site survey is needed to plan and design the dam, spillways, and other features. If you are not familiar with the use of surveying equipment, consult a licensed surveyor for this step.

Pond surveys usually 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 (see the simple method above). Larger and more complex ponds may need a complete topographic survey of the entire pond site.

All surveys made at the pond site should be tied to a reference called a bench mark. A bench mark could be a large spike driven into a tree, an iron rod driven flush with the ground, or any object that will be undisturbed during and after construction of the dam.

A detailed investigation of the soils in the pond area is also necessary. Identifying the soil type(s) in the pond area, will help determine the soil's ability to hold water and, therefore the suitability of the pond site. The soil should contain a layer of material the is impervious and thick enough to prevent excessive seepage. Clays and silty clays are excellent; coarse-textured sands and sand-gravel mixes are not. Limestone or shale areas should be avoided because of possible fractures which create leaks. Swampy areas are poor sites because they are difficult to drain and costly to maintain.

If there is a question as to whether the soils in the area are sufficiently impervious, soil borings should be done over the area to be covered by water. Three or four borings per acre may be enough if the soils are uniform. If they prove significantly different, more borings would be recommended.

The ability to hold water isn't the only reason to determine the soil type. The soil will also be providing the foundation for the dam, ensuring stable support of the structure. Good foundation materials are a mixture of coarse- and fine-textured soils, such as gravel-sand-clay mixtures, gravel-sand-silt mixtures, sand-clay mixtures, and sand-silt mixtures.

As for fill material for the dam, preferably, enough suitable material can be found close to the site so that it's not necessary to bring material in that adds to expenses. Fill material can be taken from the reservoir area, leaving the surrounding landscape undisturbed and borrow areas will not be visible. Generally, soils that are acceptable as foundation material also make good fill material.

Spillways are a necessary part of embankment pond construction in order to avoid a breach in the dam. In ponds of 10 acres or less, a vegetated spillway is sufficient to control runoff during rainstorms. Ponds larger in size should have a principal spillway in addition to a vegetated spillway. The principal spillway should be designed with a pipe inlet that controls the pond level, provides drainage for pond repairs, and allows water to escape without erosion.

Building an earthfill dam

Unless you have all the necessary equipment, you will probably want to employ a contractor to build your pond. Have a set of drawings and specifications ready to show the contractor what is to be done.

Drawings should show all elevations and dimensions of the dam, the dimensions and extent of the cutoff trench and other areas requiring backfill, the location and dimensions of the spillways, and any other pertinent information.

Specifications should give all the information not shown on the drawing 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.

Excavated Ponds

Excavated ponds are the simplest to build in relatively flat terrain. They are practical where the demand for water is small since their size is obtained by excavation. They are popular due to the ease with which they can be constructed, their compactness, their relative safety from flood-flow damage, and their low maintenance requirements.

There are two types of excavated ponds. One is fed by surface runoff and the other is fed by ground water aquifers. Excavated ponds fed by runoff can be used in areas of comparatively flat, but well-drained terrain, in a broad natural drainageway, or in the low point of a natural depression. Those fed by ground water aquifers should be located only in areas of flat or nearly flat topography where the permanent water table is within a few feet of the surface.

Determining the soil type at the location of an excavated pond is an important part of the planning and design process. Soil borings, like I mentioned for the embankment ponds, can be done for this step. If the pond will be fed by surface runoff, enough impervious soil at the site is essential to avoid excess seepage. Fine-textured clay and silty clay that extend well below the proposed pond depth make the most desirable sites. Avoid soils underlain by limestone, which can contain crevices, sinks, and channels. Observe other ponds in the area of your proposed site. If they're not holding water like they should, well...

For ponds fed by water-bearing sand or sand-gravel layer, the 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. This layer should also be at a depth that can be reached practically and economically - not more than 20 feet. Test holes drilled at intervals over the site will help indicate the normal water level in the completed pond (Check these holes during drier seasons too, to avoid being misled by temporarily high water tables).

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. An auxiliary spillway will be necessary to pass excess storm runoff around the dam. Ponds excavated in areas of flat terrain generally require constructed spillways.

Excavated ponds can be built in almost any shape, but rectangular is most common in areas of flat terrain. It is simple to build and can be adapted to all kinds of excavating equipment. The rectangular form can be edge shaped with a blade scraper to create an irregular shape that blends in with the surrounding landscape.

Plan the placement or disposal of waste material excavated from the pond in advance of construction operations. Waste material can be stacked, spread or removed from the site, depending on the situation. If not removed from the site, it can prove very functional by screening undesirable views, buffering noise and wind, filling in low areas in nearby fields, or improving the site's suitability for recreation.

Steps to building an excavated 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.

Excavate and place the waste material as close as possible to the lines and grades staked on the site.

Seal the pond to prevent excessive seepage. There are several methods of doing this:

Establish vegetation soon after construction, preferably native varieties. Trees, shrubs, grasses, and forbs provide erosion control, screening, space definition, climate control, and wildlife habitat.