Build a pond

Ponds add scenic beauty to a property and provide opportunities for boating, swimming and fishing. There also are many practical uses for a pond — livestock watering, crop irrigation, fish production, wildlife habitat and as an emergency source of water for fighting fires.

Siting and Planning a Pond

Topography

Locate your pond where the largest storage volume can be obtained with the least amount of earth moving. There are two basic ways to create a pond — digging a hole or building a dam. Usually, the form is implicit in the site. On flat terrain, where the water table is close to the surface, or where a nearby stream or well can be directed to fill it, a dugout pond works best,” he says. Deeply excavated ponds with a smaller surface area (8-14ft deep) are recommended in arid areas where evaporation losses are high and rain is scarce (5-7ft in temperate climates).
But often the answer is a combination of methods, a dug-and-dammed pond.

Soil Types

Deep, well-drained soil with lots of sand and gravel may be great for farming, but it is lousy for ponds because it doesn’t hold water well. Heavier clay soil, on the other hand, holds water much better and is perfect for ponds. The water-holding capacity of less-than-perfect soil can easily be increased by compacting the soil with heavy equipment, adding clay blankets, using sealers such as bentonite (a fine-textured colloidal clay). Some small ponds can be lined with heavy plastic or rubber sheets.

Water Sources

Your geographic location, the source of your water (surface runoff, a spring, a stream or a well and pump) and its reliability will largely determine the size and depth of your pond. For ponds that depend solely on surface runoff, the size of the watershed drainage area surrounding the pond is a critical factor. To fill a one-acre pond in Ohio to a depth of 5 feet, you may only need a watershed of 15 acres; in western Kansas, though, it may take 175 acres to provide enough water; in arid Western states it may take 300 to 500 acres.

Costs

Unless you pull a Nearing and dig your pond by hand, hiring a bulldozer to build even a modest pond will cost $3,000 to $5,000. Sometimes government agencies will share the cost through watershed restoration and conservation projects.

Maintenance

Keep your pond surrounded by large grassy areas to prevent soil from washing into the pond from nearby fields. Also keep in mind that the ponds own water can cause soil erosion. Wind-whipped waves can eat away at a ponds banks, dam and spillway. Common solutions include breaking up waves with an obstacle such as a floating log boom, or building rock-lined banks — called riprap — which work well where the water level fluctuates widely. Keep livestock out of your pond as much as possible, both to prevent erosion and to maintain water quality.

Build a Pond: Safety and Self-Reliance

Many pond owners install a dry hydrant, a 4- to 6-inch-diameter plastic sewer pipe, to provide a quick and reliable hose connection.

Overflow

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To create a dug-and-dammed pond, like the one in the illustration, first remove the topsoil covering the foundation area, and dig a core trench (shown as a dark gray triangle) that extends to clay or bedrock. Then fill the trench with well-compacted dense material. To prevent the dam from washing out during heavy rains, install a vertical overflow pipe and horizontal spillway pipe with anti-seep collars (to prevent leaks from developing along the pipes) at the base of the dam. The top of the overflow pipe should be about 2 1/2 feet below the top of the dam. After the pipes are installed, dig soil from the pond area and construct the dam over the core trench, with the front (water) side of the dam at a 3:1 slope and the back of the dam at a 2:1 slope.
To create a dug-and-dammed pond, like the one in the illustration, first remove the topsoil covering the foundation area, and dig a core trench (shown as a dark gray triangle) that extends to clay or bedrock. Then fill the trench with well-compacted dense material. To prevent the dam from washing out during heavy rains, install a vertical overflow pipe and horizontal spillway pipe with anti-seep collars (to prevent leaks from developing along the pipes) at the base of the dam. The top of the overflow pipe should be about 2 1/2 feet below the top of the dam. After the pipes are installed, dig soil from the pond area and construct the dam over the core trench, with the front (water) side of the dam at a 3:1 slope and the back of the dam at a 2:1 slope.

Books

  • Earth Ponds: The Country Pond Maker’s Guide to Building, Maintenance and Restoration by Tim Matson
  • Earth Ponds Sourcebook: The Pond Owner’s Manual and Resource Guide by Tim Matson
  • Earthponds.comTim Matson’s Web site.

Build an ecopool DIY

The cheapest and most ecologically sound way to build a swimming pool is simply to hollow a hole in the ground. You can make your pool as shallow or as deep as you want, but the key is to make sure the sides slope: Otherwise the soil will cave in. The ratio should be a 1-foot vertical drop for every 3 horizontal feet.

Once you’ve dug the hole for the swimming pool and the plant zone, you have a couple of options, depending on your soil conditions, to make sure the pool holds water: You can apply a layer of bentonite clay to seal the soil or lay a synthetic liner. Bentonite is usually the cheaper option, averaging 35 cents per square foot. Liners can cost 25 cents to $1 per square foot, depending on their composition and weight.

Particularly sandy soil can require up to 12 pounds of bentonite per square foot, as opposed to 6 pounds in clay-rich soil. Bentonite also can be troublesome when the surrounding soil is very dry. In arid climates, Zingaro recommends bentonite be applied beneath a plastic liner that is woven or textured on the bottom. This liner keeps the bentonite from shifting. In more humid climates, bentonite can be applied directly to the soil. Before treating your pool with bentonite or any other clay powder, thoroughly compact the soil. You can do this with a lawn roller or a plate compactor. Then, while wearing a mask, spread a 2- to 3-inch layer of bentonite powder along the pool sides and bottom. Pack it down with a tractor or plate compactor. Then apply another foot of quality topsoil and compact again.

After the bentonite clay or a liner is installed, cover the bottom of the pool with 4 to 5 inches of gravel. The gravel provides a habitat for beneficial bacteria, which help biodegrade leaves or other natural materials that sink to the bottom of your pool. Make sure you use clean gravel

Reserving at least 50 percent of your pool’s surface area for shallow plants, either at one end or in a ring around the sides, eliminates the need for chlorine and expensive filters and pumps. You’ll want to separate the swimming area of your pool and the filtration area, or plant zone (see the illustration in the image gallery). A rim within an inch of the water’s surface keeps plants in their place but allows water from the swimming area to move to the plant zone for filtering, As water passes through the fibrous root structure of the plants, bacteria concentrated on the plants’ roots act as a biological filter, removing contaminants and excess nutrients in the water. Decomposer organisms, also found in the plants’ root zones, consume the bacteria, effectively eliminating underwater waste buildup.

Inside the plant zone, the water should get steadily deeper, reaching a maximum depth of 18 inches near the swimming zone. The outermost 6 inches of the plant zone will be 2 to 3 inches deep, providing a home for taller aquatic plants. Submergent and floating vegetation occupy the deeper area.

Once your pool is constructed, you’ll need to prepare the plant zone with 3 to 6 inches of soil.

Sedges (Carex) and rushes (Scirpus), both aquatic plants, make great emergent vegetation for your pool’s perimeter. You can also consider lesser cattails (Typha angustifolia) and aquatic irises, though be sure to ask which varieties won’t overcrowd other plants. Pickerel weed (Pontederia cordata), arrowhead (Sagittaria) and water primroses (Ludwigia) are all contenders for the shallowest areas of your pool. Be sure to include submergent plants such as common waterweed (Elodea) and hornwort (Ceratophyllum) for their high oxygen output.

In water 6 to 18 inches deep, plant a mix of floating, submergent and emergent plants. Water lilies (Nymphaea) adapt to any depth, so use them liberally. Floaters, such as pondweeds (Potamogeton) and common duckweed (Lemna minor), drift freely on the surface and quickly cover the surface of the plant zone.

Promote plant growth and deter algae by adding plants and eliminating phosphorous to maintain a lower pH (5.5 to 6.5).

The water needs to circulate continuously for the plants’ roots to cleanse the pool. You also may need to aerate the water so the water organisms’ oxygen needs are met. (Without adequate oxygen, your pool could become stagnant, harboring odoriferous anaerobic bacteria.)

Underwater aeration, which uses less energy than constructed waterfalls and circulates water more effectively, involves diffusing air at the pool’s bottom. You can build your own aerator, using an air compressor (1/4-horsepower for a pool smaller than an acre) and high-strength tubing that connects to a diffuser. The diffuser (see “Pool Equipment Sources” at the end of this article), which bubbles air through the water, rests in the deepest part of the pool, where swimmers are not likely to damage it.