Pond Construction Considerations
Things to Consider When Constructing a Pond
Creating ponds as aesthetic and recreational amenities or as water sources for agricultural have requirements that must be considered. One must consider various site conditions when planning for a pond to ensure a suitable location. Be sure to check on federal, state and local requirements before you start to dig.
Most pond projects will benefit from technical and regulatory expertise.
What is your water source?
An adequate water source is needed to maintain water levels. Supply is available from four types of sources.
- Overland drainage
Surface runoff from precipitation or a flowing spring traveling overland as sheet flow or concentrated in a drainage way can be collected in a pond basin. Ponds with this type of water source are located on or below sloping lands. Annual precipitation rates and drainage area characteristics determine the adequacy of the water supply for each potential pond site.
In areas where groundwater is near the surface, excavating into and below it will create a pond. Groundwater-fed ponds are generally located in flat low lying areas and do not require a surrounding embankment.
- Flowing waters by an in-stream impoundment
This method will require professional consulting and is often not as easily managed as the above two methods. Constructing a dam across a water course will capture water and create a water body. Careful consideration should be undertaken before pursuing a pond of this nature. Environmental concerns such as blockage of fish passage or warming of down stream waters can cause adverse impacts. Also, sediment from upstream areas will become trapped behind the structure requiring periodic removal to prevent loss of water depth in the pond basin.
- Flowing waters through diversion
A water source can be provided by diverting a portion of a stream's flow to the pond area or excavated basin. The diversion may use a weir or similar structure to direct water through a pipe or ditch to the pond site.
- Drainage Area
Drainage area is a measure of the amount of land surface contributing water by runoff to a pond site and is presented in square miles or acres. Runoff volumes are determined by precipitation, soil type, vegetative cover, and topography. For ponds relying on surface runoff, the drainage area must provide an adequate supply of water to maintain pond water levels. Too large a drainage area should be avoided as excess runoff during storms can damage embankments and spillways or result in pond washout.
Ponds fed by surface runoff must have impermeable soils beneath the pond basin or be lined with clay to prevent excess downward seepage, otherwise, the pond will not maintain water. The excavating of test pits at the proposed pond site allows for an evaluation of soil type and suitability. If suitable clay is not available on site, appropriate soils or soil amending products may be obtained from off-site.
Pond Design Options
Materials and structure choices vary depending on your needs and site conditions. The basic design options are as follows:
- Dugout Pond - A basin for holding water is created by excavating soils in an area which is generally flat or in a depression or low point within a broad drainage way. This type of pond obtains its source of water from overland runoff, a diversion of flowing water or from groundwater.
- Vegetated Earthen Impoundment Structure - The pond is created by erecting an earthen embankment across a water course or overland drainage way. These structures are placed on sloping lands to accommodate the incorporation of the embankment with the natural ground on the upslope side of the pond. Often, the soils for the embankment are obtained from within the pond site during the shaping and deepening of the pond basin. Establishment of a hardy vegetative cover of grasses and legumes (not trees or large shrubs) provides an erosion resistant slope.
- Impounding Structures Made of Other Materials - Rock, wood, concrete, and steel or a combination of these materials can also be used to construct dams. The design and construction of structures of this nature are often complex and more costly than a totally earthen structure but may be necessary to ensure long term structural integrity.
Some important pond design basics are:
- Pond Size, Depth, and Configuration - Determining adequate pond surface area and depth are often a function of volumes of water necessary to meet usage needs such as livestock watering, irrigation, or fire protection. Pond depth may also be predicated on recreational uses such as swimming, fish rearing, or wetland creation. The configuration or shape of the pond is often a matter of aesthetic consideration. An irregular shoreline that blends in with the surrounding terrain is generally most pleasing to the eye. Physical conditions may also dictate pond dimensions, such as depth of impermeable soils or slope of lands adjoining the pond site. Site conditions that result in back-flooding of neighboring properties must be avoided.
- Spillway Capacity - The spillway, such as a vegetated earthen channel around the dam, provides an outlet for excess water. It is critical that the spillway is sized to pass flood waters and be stabilized to prevent erosion or washout of the structure.
- Structural Integrity - Foundation preparation, construction specifications, and spillway design, are the most important components of a pond created by an impounding structure. These factors determine the structural strength, water retaining capability and safe function of the structure.
Other Design Considerations - The steepness of pond basin side slopes affects light penetration to the pond bottom. If you wish to minimize areas supporting rooted aquatic vegetation, pond side slopes should be steep to maximize the area of deep water. On the other hand, a pond with steep banks will be subject to muskrat problems. Shallow tapering side slopes create broader areas for the establishment of rooted aquatic vegetation. A common rule of thumb is 10% of the pond deeper than 8 feet and a 3:1 bank slope.
You may wish to provide a structure that allows draining of the pond or provide for a constant release of water from the pond bottom. This can be accommodated through the installation of a pipe under a dam or embankment with a valve for controlling water flow. A drop inlet trickle tube can be installed to release normal overflow waters through the pipe, rather than regularly utilizing an over the top of structure spillway.
Fish Stocking and Rearing
Most ponds can serve as a recreational fisheries resource in addition to serving other primary functions. Fish stocking in private ponds may require a permit.
Advice on fish species and management choices can be obtained from the pond managers at Smith Creek Fish Farm and your local fisheries/environmental office.
Pesticides may be applied to ponds to control weed growth, algae blooms or to remove undesirable fish. Chemical may need to be applied by a registered pesticide applicator. Smith Creek Fish Farm recommends that aquatic pesticides be used by a certified aquatic applicator. Wetlands permit is also required for the use of pesticides, if the pond is contained within a regulated wetland. NY Department of Environmental Conservation.
Smith Creek Fish Farm Lake and Pond Management