CORVALLIS, Ore. – Of all the habitat features that can attract wildlife to your yard, a pond can be one of the most rewarding. Planning a garden pond to build in the spring can be an interesting winter project.
"Besides drinking, animals use water for feeding, bathing, regulating body heat, resting and cover,” said Nancy Allen, a faculty member in the Oregon State University fisheries and wildlife department. "In the Pacific Northwest, some of the species most attracted to ponds are raccoons, deer, dragonflies, songbirds and waterfowl."
A pond creates natural beauty, and the more natural features it has, the more attractive it is to wildlife. Ponds can be any shape or size. They can be still or have running water or fountains. Many species are attracted to moving water, which also discourages mosquitoes.
Adding fish to the pond to help control mosquitoes, however, can be a problem when the pond overflows. Allen suggests placing bird and bat boxes near the pond instead.
An Oregon State University publication (EC 1548) Create a Garden Pond for Wildlife describes how to build a simple pond to attract wildlife and how to keep it safe and healthy and is available online.
The first step is to check with local zoning or planning offices to be sure that the pond is safe and legal. Also, check with your insurance company for safety requirements.
"The pond should fit in with the natural landscape of the land and have a curved, irregular shape. For smaller yards, a pond that is three-by-five feet is a good size," Allen said. "A larger yard could hold a pond five-by-eight feet or larger."
The pond should be at least 20 inches deep at the deepest part. Shallow water around the edge or at one end should include plant shelves as habitat for wildlife. One side of your pond should have a gradual slope. A good slope is a drop of six inches for every three horizontal feet.
Consider all underground utilities, tree roots and other potential obstacles, Allen advises.
"Keep your pond above the water table to prevent damage to your liner,” she said. “You can check the high water line in winter. Dig a small hole the same depth as your proposed pond and observe it for 24 hours. If the hole fills with water on a day with no rain, your water table is high in this spot. Be sure your pond depth is above this level."
Plan where your pond will drain when it overflows from rain or when you clean it. You can channel water to your yard or down a hill, or you can create a small wetland to collect the excess water.
To see how your pond will look in different locations, use a garden hose or string to make an outline. Make sure you can see it from the house or from wherever you want to view it.
"Most ponds, unless they are very shallow, should get at least five to six hours of sunlight per day," Allen said. "This allows enough sunlight for plants to grow but enough shade to prevent excess growth of algae." Don’t place your pond directly under trees or over-hanging shrubs. Leaves can make the water too acidic for aquatic life and, when decomposing, use the oxygen and cause odors.
Also, when considering location of the pond, remember that wildlife need a "travel corridor" of tall grass to move safely to your pond. If you need to fill and change the water, place your pond near a water supply. If you plan to have running water and/or a pump and filter, you need to place your pond close to a supply of electricity.
The Extension publication gives directions on buying pumps and filters and choosing and installing a liner. Other details include how to excavate the hole, fill the pond and add edging, sand or small rocks.
You'll find information on what types of native plants to put in – submerged, floating and marginal – and how to care for them. You'll also learn issues about native wildlife species and coexistence with humans.