Poorly constructed lakes and ponds make proper lake management difficult. Water levels may fluctuate radically because of pond seepage, or the lake may have an inadequate watershed to keep the water body at or near capacity. Or worse yet, a poorly constructed pond could suffer from both of these conditions. Improper pond construction will also allow aquatic weeds to grow rapidly in shallow areas.
In addition, erosion and contamination from the watershed may make good lake management nearly impossible. For assistance in lake construction or renovation, contact an engineer trained in pond and lake construction or the USDA Natural Resources Conservation Service (NRCS). They can provide assistance in proper design, layout, and monitoring construction of ponds.
All lakes and ponds should be designed and maintained with the following guidelines:
- The dam should have a compacted clay core.
- Soil lining the pond should be a minimum of 30 percent clay.
- Lake size should be matched to watershed area.
- Banks should slope rapidly to a depth of at least 2.5 feet.
- Drains and overflow pipes should be built through the dam.
- An emergency spillway should be constructed for periods of heavy runoff.
Unfortunately, lake and pond leaks caused by poor construction are common. Dams must be constructed with a compacted clay core that is trenched into an impervious soil or rock layer below the pond bottom. Trees or other woody vegetation should never be allowed to grow on the dam, because roots will eventually penetrate the core and cause the lake or pond to leak.
And although lake managers will want to ensure that no water is lost, there will be times when excess water is available. Drains allow water levels to be regulated for better control of aquatic weeds and fish populations, and for easy access to repair or renovate the lake or pond.
Most ponds and lakes will generally require 4 to 100 acres of watershed per acre-foot of pond storage. More watershed is required in dry climates and less in less in areas that receive higher amounts of precipitation. Soil types, slope and vegetation covering the watershed will affect run-off. Generally, more area is needed if the watershed is wooded than if it is open, since woody plants will intercept rainfall and groundwater. If the watershed is too large, a diversion ditch around the lake or pond may be needed to keep the water body from flushing too rapidly.
Lake or pond banks should slope rapidly, such as a 2:1 or 3:1 ratio, to a depth of 2 1/2 feet or more because aquatic weed growth occurs most easily is shallow water. Aquatic plants do not easily establish themselves at this depth or deeper, especially if a lake fertilizer program is in place and a good algae bloom is maintained.
Lastly, with regard to the lake’s watershed, several aspects outside the water body itself will impact the internal dynamics of the lake. Fields adjacent to ponds should have grassy borders. Grassy buffers ranging from 50 to 100 feet wide between the field and the lake reduce both soil erosion and pesticide contamination that can kill largemouth bass, catfish, and any other fish stocked in your lake.
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