The Northern Virginia Soil & Water Conservation District provides advice on planning and constructing ponds or maintaining your existing pond.
General pond maintenance includes aquatic weed and algae control, dam inspection, fish stocking, shoreline erosion control and water quality management.
Aquatic weed and algae control
A pond may be filled with a nuisance aquatic weed or algae. How can the owner get rid of it? Solutions may include biological, physical, or chemical methods.
As an example, to rid a pond of the aquatic weed hydrilla, a pond owner might try the following:
- Biological—Introduce triploid grass carp (a sterile fish) that will feed on the hydrilla.
- Physical—Remove the hydrilla by gently uprooting the whole plant. A boat may be needed to do this.
- Chemical—Use an appropriate EPA approved herbicide.
Often a combination of two or all three of these approaches is most effective.
Establishment of deep-rooted vegetation on the dam of a pond is discouraged because the root system may compromise the stability of the dam. For example, when a tree dies, the root system may rot. The decaying root system may provide a conduit for water and the dam may start to seep. Mature trees on dams also pose a risk during severe storms. Storm winds and saturated soil conditions may cause a tree to topple or uproot taking a portion of the dam with it. However, if mature trees are already established on a dam, it is not advisable to cut them down. Instead, thin the branches to make the trees less "top-heavy."
Seepage around a dam most commonly occurs around the barrel (the horizontal pipe that takes water out of the pond) or along the toe of the dam.
To prevent this:
- Seal the pond side of the dam with bentonite; or
- Install a perforated pipe to intercept seepage.
In most cases, it is advisable to seek professional help with these tasks.
To ensure a healthy fish population, a proper ratio needs to be maintained among or between the species. Overabundance of one species compared to another creates an imbalance which affects fish growth and productivity.
The most common fish combination in Northern Virginia is largemouth bass and blue gill. Largemouth bass prey on blue gill fingerlings. If the blue gill population is low, the largemouth bass will not have enough to eat, they will become stunted and their reproduction rates will drop. Blue gill are highly prolific. If the largemouth bass population is too low, the blue gill population may grow quickly. Over-population of blue gill creates severe competition for food within the pond. Lack of food slows and/or stunts the fishes' growth. The blue gill, although plentiful, stay very small in size.
To enhance fishing opportunities in a pond, you may add catfish to the bass/blue gill mix. As bottom feeders, catfish do not affect the balance of the other fish.
Wave action, surface runoff entering the pond and wildlife activities can all cause shoreline erosion.
If shoreline erosion becomes a concern, allow a buffer of natural vegetation to grow or plant native vegetation at the edge of the water and on the shore. The root systems and stems of the vegetation will reduce erosion due to wave action and surface runoff. Shoreline vegetation also provides hiding places for predators and may discourage Canada geese and other wildlife whose activities can cause erosion.
In some cases, reinforcement of the shore using stones or timber may be necessary.
Poor water quality in a pond often is a result of poor use and/or management of land that drains to the pond. Examples include over-application of chemical fertilizers or location of animal waste piles upslope of a pond.
Unfortunately, a pond may receive surface runoff from land that is not maintained by the pond owner. In such cases, educating neighboring land owners or users can help.
The smaller the pond, the greater the potential for poor water quality. If adjusting land use in the pond's drainage area is not possible or sufficient to improve water quality, simply aerating a pond to increase dissolved oxygen in the water can greatly improve water quality.
Building a Farm or Amenity Pond in Fairfax County from the Northern Virginia Soil & Water Conservation District.
Private Pond Management from the Virginia Department of Game and Inland Fisheries.
Native Plants for Conservation, Restoration and Landscaping
from the Virginia Department of Conservation and Recreation.
The riparian buffer plant table includes species appropriate for pond shoreline projects.
Dealing with Excess Aquatic Vegetation in Your Pond from the Northern Virginia Soil & Water Conservation District.
Backyard Pond: Backyard Conservation Tip Sheet from the Natural Resources Conservation Service of the U.S. Department of Agriculture.
Ponds—Planning, Design, Construction from the Natural Resources Conservation Service of the U.S. Department of Agriculture.