Managing Ponds and Lakes for Aquaculture and Fisheries in Missouri: Pond Construction and Management Considerations
Charles E. Hicks
Robert A. Pierce II
Fisheries and Wildlife State Specialist
School of Natural Resources
A properly planned and constructed pond or lake can be a great asset on your property (Figure 1).
Private ponds and lakes can be used for recreation, fishing, hunting, boating, swimming and other activities. They can also be used as a water source for livestock, fire protection, irrigation and production of fish for food or sale. A pond that provides these benefits and consistently produces good catches of fish is a result of proper planning, construction and management.
Properly constructed ponds benefit from even a minimal level of management. The fundamental considerations for managing a pond for fishing include:
- Proper pond construction and watershed management,
- Fish species selection and stocking,
- Determining fertility needs,
- Managing for a balanced fishery,
- Proper harvesting and record-keeping,
- Managing water quality and understanding pond dynamics, and
- Aquatic plant management.
Two pond construction styles are used in Missouri, depending on a pond’s intended purpose and the availability of water. The first is the watershed pond, which takes advantage of the topography of the surrounding land to collect and store water. In some cases, a single dam may be all that is necessary to construct such a pond. Using runoff water will typically reduce the need for digging a well for water supply. The second common style of pond in Missouri is referred to as a levee pond. Levee ponds are commonly used for commercial aquaculture production in locations where well water is economically feasible, and these ponds tend to be more expensive to build and maintain.
Because watershed ponds are generally cheaper to build and maintain, they account for most of the farm ponds in Missouri. Therefore, this publication focuses on construction and management of watershed ponds.
Private ponds can have many uses and provide a wealth of recreational opportunities, though a pond's primary purpose should be determined before construction..
Clearly define your objectives for the pond well before construction begins. Site selection, design and construction require a management plan that outlines the activities necessary for maintaining a pond.
For example, management and day-to-day maintenance will often differ depending on your primary goal for the pond. Sport fishing and aquaculture production will require different activities, such as:
- Producing a balanced fishery to catch good numbers and sizes of bass and bluegill,
- Producing trophy bass or trophy bluegill,
- Fishing for channel catfish,
- Fishing for hybrid sunfish,
- Producing a balanced fishery for sport fishing but also allowing for cage culture, and
- Commercial aquaculture production.
Consider the topography
Site selection will determine the size and function of a pond. The topography of your property will directly affect building costs and can dictate potential uses and management objectives. Ponds need a source of high-quality water, so the best sites tend to be higher up within a watershed. Choose a site that requires the least amount of soil to construct the dam and provides enough depth; at least 6 to 7 feet at the deepest area. Under the best of conditions, more than half of the pond should be at least 5 feet deep. The best site is an area that will hold the most water relative to the dam height.
Construct a dam across a narrow section of a steep valley in a location where the slope allows you to flood a large area. Avoid locations with flowing creeks or streams, as they flush the pond and make managing water chemistry difficult.
Most streams and springs are regulated by the Missouri Department of Natural Resources and may not be obstructed for the formation of a private lake or pond. Contact the Soil and Water Conservation District, Missouri Department of Natural Resources or the Missouri Department of Conservation (MDC) for information on regulations affecting pond construction.
Consider the surrounding watershed
Pond size and amount of water storage are determined by the overall acreage of the surrounding land that provides runoff to the pond, commonly known as the watershed. In Missouri, especially in dry years, try to maintain a watershed ratio of 10 to 20 acres of land to 1 surface acre of water. Although many ponds have been constructed in areas with smaller watershed ratios, most will dry up during periods of extended drought. Some sites may be unsuitable simply because of topography, geology or soil conditions. Many areas in Missouri are too rocky because of exposed bedrock, which poses many problems for pond construction and maintenance.
Other factors to consider include the soil type, vegetation and ongoing land-use activities that occur within the watershed of a pond or lake. For example, a pond should not be constructed below an intensive animal production area, especially if runoff from the area will drain directly into the pond or lake. Animal wastes will overload the pond with increased nutrients — primarily nitrogen and phosphorus — that will cause an overabundance of aquatic plants. The added nutrient load will lower oxygen levels, which is the primary cause of fish kills.
The quality of the watershed is vital to the health of the pond and affects what management activities will be necessary. Watersheds consisting of high-quality grasslands or pastures provide high-quality runoff water. Grasslands and pastures tend to trap sediments and reduce the influx of nutrient overload, and are often consistently limed. Water flowing into the pond should ideally have a pH between 7.0 and 8.0, which is slightly alkaline. Water with a higher alkalinity tends to be more conducive to a robust fish population. Runoff from watersheds with woodlands and forests tends to be more acidic and, therefore, not as good a source of quality runoff water. Deciduous trees, such as oak and hickory, lose their leaves annually and tend to build up acidic conditions in the soil.
Missouri has two common types of sedimentary rock formations: sandstone and limestone. Runoff from limestone is best for a pond because the calcium and magnesium carbonate produce higher alkalinity levels in the water.
Monitoring and maintaining alkalinity levels in your pond serves several purposes. It stabilizes the water’s pH and prevents large swings from low pH (acidic) to higher pH (alkaline) naturally caused by ongoing biological processes within the pond. An adequate alkalinity level will act as a buffer against changes in pH level due to naturally occurring processes.
Consider the soil characteristics
Soil should be one of the main considerations when selecting your pond site. Soil consistency is extremely important, and soil with suitable amounts of clay is necessary for sealing a dam. Clay may also be necessary for sealing the basin of the pond; soil that is at least 20 percent clay is necessary to hold water.
The cost of building a pond is often determined by how much soil must be moved to construct the dam. Costs can escalate rapidly if your site lacks enough soil for construction. The U.S. Department of Agriculture’s (USDA) Natural Resources Conservation Service office provides expertise in evaluating soils capable of holding water for a pond. They provide technical assistance with design and construction, and may also provide cost-share assistance (see Additional resources for more details).
When to build
Ponds can be constructed at any time of year, but summer is best because weather and soil conditions usually allow the use of heavy equipment (Figure 2). Fall and winter rainfall will fill the pond, which allows you to stock fish in the spring, the ideal time for stocking fingerlings.
Take special care during the design and construction phases to ensure that the amount of watershed matches the desired pond size. .
The size of your pond will directly affect your management goals and objectives. Small ponds (1 to 5 acres) provide excellent fishing opportunities. Larger ponds and lakes can also provide excellent fishing but have other potential uses, such as irrigation, swimming, boating and hunting. Plus, they are less susceptible to changes in water level. For surface runoff ponds and lakes, the area of land that flows into the pond will determine its size. For each surface acre of pond water, 10 to 20 acres of drainage area is usually required.
Pond size will dictate how many fish to stock if sport fishing is your primary goal. Many people have difficulty estimating the surface area of their ponds. Overestimating the surface area can lead to overstocking and other management issues. If your pond’s surface area fluctuates considerably, it should be stocked based on the average annual low-water surface area. Use the formulas for calculating the surface area (in acres) of common pond shapes provided in Figure 3 to determine the size of your pond.
The Missouri Department of Conservation has a pond area estimator available at http://mdc.mo.gov/node/5990. Also, recent advances in global positioning system (GPS) technology allow you to easily calculate pond surface acreage using a handheld GPS unit with area calculation programming.
Obtain a rough estimate of your pond's surface area using these formulas for common pond shapes.
Ponds should have an average depth of 5 to 6 feet but not exceed 10 to 12 feet at any point. At least half of the pond should be 4 to 5 feet deep so fish can forage on the pond bottom even during the summer months when low oxygen concentrations are common in deeper water. This depth also sustains fish populations during times of drought. During the summer, water evaporation can reduce water levels by up to a half-inch per day, and ponds can potentially lose 2 to 3 feet of water depth.
The bank surrounding a pond should drop quickly to at least 3 feet deep to minimize the risk of aquatic plants taking root.
Pond dam and water control structures
Dams should be at least 8 to 12 feet wide at the top, depending on the height of the dam. If a dam is less than 12 feet tall, it will require an 8-foot top width. A dam taller than 15 feet will require a 12-foot top width. If you use the top of the dam as a road, it should be at least 16 feet wide across the top.
Figure 4 illustrates a recommended pond dam (levee) and an appropriate water control structure. The combination of drain and overflow pipes and an emergency spillway makes pond management an easier task. Placing the drainpipe on the pond bottom allows you to completely drain the pond and efficiently manage the water level.
Many areas of Missouri have soil that requires dams be cored with clay to prevent seepage. The slope of the dam should not be steeper than 1-to-3 on the waterside (a 1-foot rise for every 3 horizontal feet). On the backside, a 1-to-4 slope will allow you to safely maintain the vegetation on the dam.
Moving material will comprise a significant portion of the cost of dam and pond construction. Use this simplified method of estimating the volume of material necessary to construct a dam on your site:
Although the result is an approximation, it can be useful in determining construction costs. A more precise estimate will require that you properly survey and calculate the expected dam height, width and slope.
Figure 5 shows another recommended water control structure, the bottom draw-off device. This design is less costly to implement and uses a trickle tube to remove excess water from the pond during periods of normal runoff, which preserves the emergency spillway. The emergency spillway is vital to maintaining the structural integrity of your dam, so keeping it dry under normal circumstances should be a priority.
Having an adequate amount of freeboard, which is the distance from the water’s surface to the top of the dam, not only makes the dam safer but also ensures that it will not be topped by the water. One foot of freeboard is necessary at the standpipe, or overflow pipe, which drains normal runoff when the pond is full. The drain pipe, or outlet pipe, should be large enough to drain normal runoff before it reaches the spillway (usually about 3 to 6 inches in diameter). This pipe usually has a hood or canopy inlet. You may want to install a pipe on the bottom of the structure to serve as a supply for livestock water or to draw down water levels for controlling aquatic vegetation or conducting pond basin maintenance. All pipes in the dam structure should have antiseep collars on the upper and lower sides of the dam to prevent water from seeping out along the pipe and eroding the dam structure. Pipes can be made of corrugated metal, aluminum, steel or polyvinyl chloride (PVC); consult an expert to determine which pipe material is best suited to your dam.
Fit a larger pipe over the standpipe to draw water from deeper areas of the pond, where oxygen levels may be low. The base of the pipe should be 18 inches off the pond floor and extended 12 inches above the water’s surface (Figure 6). This draw-off pipe will circulate water from the deeper areas of the pond to improve water quality, increase available fish habitat and reduce the risk of a fish kill by removing low-oxygen water.
The overflow pipe is used as the outlet for normal water flow through the pond. The emergency spillway is an area lower than the top of the dam that runs on one side to safely release excessive runoff resulting from heavy rainfall. Seeding and establishing a stand of grass stabilizes the soil within the spillway and minimizes the risk of erosion. Flow through the spillway should be slow and shallow to prevent erosion near the dam structure, and it should not meander near the dam base but end in an area where the water can spread out. The spillway should be large enough to handle a historic downpour and should be protected with vegetation or riprap.
Seepage below the dam is a common problem if the site is incorrectly prepared, but a dug-out cutoff or core trench addresses this problem. The trench should be at least 12 inches deep and dug to impermeable materials (materials that fluids cannot pass through, such as clay) below the natural soil level. The trench should be dug along the center of the dam and as far up the sides as there is permeable material. If the trench breaches an existing channel or old streambed, it must be dug past any rock or gravel to impermeable material.
Soil type and compaction are principle factors that affect dam safety and permanence. Only about 6 to 8 inches of soil should be added before compaction with heavy equipment such as a sheepsfoot roller. A bulldozer alone will not provide adequate compaction. The soil around the spillway and water supply pipes must be compacted separately using power or hand compactors. Compaction is a slow process usually done as new levels of material are added during construction.
You can find helpful illustrations of a properly constructed pond dam, spillway and water control structures in the MDC’s Missouri Pond Handbook (see Additional resources).
Diagram of a pond dam with drainage and water control structures. This design is common among irrigation lakes and levee ponds.
The hooded trickle tube drains and removes excess water from a pond during periods of normal runoff.
An example of a bottom draw-off device that can be used to remove deep, low-oxygen water to improve the water quality and enhance available habitat within the pond.
Establish perennial vegetation on the dam as soon as possible to prevent erosion, muddy water and maintenance problems. Tall fescue, a nonnative perennial cool-season grass, is a common choice because it is a quick-establishing turfgrass that tolerates frequent mowing. Native warm-season grasses, such as switchgrass or big bluestem, are also excellent choices as they have deep root systems and provide higher quality wildlife habitat. Native warm-season grasses also require less frequent mowing and tolerate drought conditions better than nonnative grasses. Do not mow these grasses shorter than 6 inches.
If dam construction is completed before or after planting dates for these grasses, establish a temporary cover to limit soil erosion until more permanent grass cover is established. Winter wheat, oats and rye are good choices. Lime, fertilize and seed at recommended rates as soon as construction is completed.
Trees and shrubs should not be allowed to grow on the pond dam. They will weaken the dam and increase the likelihood of a leak or failure. However, leave in place any large trees already growing on an existing pond dam, as decaying root systems from a felled tree may weaken the dam.
The best time to decide how you will manage the pond basin is during construction. Inspect the pond basin and take soil samples after all other digging and dirt work is complete. The University of Missouri Soil and Plant Testing Laboratory (http://soilplantlab.missouri.edu/soil) can test the sample to determine whether the soil pH needs to be adjusted. In many cases, the pH may be low and you will need to add lime to help ensure the productivity of your pond. Before filling the pond, you can also establish winter wheat, rye, millet or other suitable grasses on the pond bottom to reduce erosion and siltation and to enhance the production of a variety of aquatic species that will be important food sources for fish once the pond is stocked.
If fishing is your goal, leave some trees, bushes and brush piles to serve as fish attractors. These structures provide habitats for largemouth bass, bluegill and many species that are important food sources for fish.
As much as 10 to 25 percent of the pond basin should provide some type of cover. Trees and brush should not be left in shallow areas, in narrow coves or along the pond bank, as these areas will be more difficult to fish and aquatic plant problems will eventually develop.
Fish attractors can be established in ponds that have no trees or brush available for cover. Refer to the Missouri Pond Handbook for more detailed information.
With proper planning and design, watershed ponds can offer many opportunities for sport fishing, recreation and fish production. Decide before construction how the pond will be used so an appropriate management plan can be implemented. Keep in mind that compromises may be necessary when determining the objectives for your pond.
Once a pond is completed, its success will depend on a variety of management practices that include establishing and maintaining good fish populations. Stocking the correct species and numbers of fish at the appropriate time of year, achieving a balanced harvest, water quality management and aquatic vegetation management are a few of the basics that will need to be considered and will be discussed in subsequent MU Extension publications.
In addition, seek advice from the Missouri Department of Conservation and the USDA Natural Resources Conservation Service. These organizations provide useful management resources and information on pond construction.
Charles Hicks and Robert A. Pierce II