Monday, October 8, 2012

Renovating Ponds

Some say, “When life gives you lemons, make lemonade,” and this drought has certainly given us a lot of lemons. One way to turn around a negative effect of the drought is to renovate a dry older pond.

A problem with many older, small farm ponds is their low to almost no water holding capacity due to filling with silt. These old, shallow ponds are often ignored because of the cost and trouble associated with a renovation. 

Typically, pond renovation begins with the dam being opened to release the water. The use of drag lines or back hoes to renovate a “wet” or full pond is not nearly as efficient and is usually more expensive than a dry pond renovation. The drought provides an opportunity to renovate without damaging the dam and having to wait for the pond to drain. 

Minimum depth should be 8 feet. The dam and sides of the pond should be rather steep (not to exceed a 3:1 slope) to aid in reducing marginal aquatic weed establishment and growth. Typically, the water entrance end is a shallower slope. The 8 foot depth and steep sides should give sufficient water to leave some reserve capacity even during the next drought increasing the likelihood of fish survival. 

Silt cleaned from the pond should be placed where it will not wash back into the pond. If there is a clay layer spread over the bottom of the original construction to aid in sealing, this should be preserved in place or saved nearby to be reapplied. 

If the dam has trees or shrubs, they should be removed with the roots to guard against future leaking or weakening. Dams typically have been eroded and should be rebuilt. At the same time, damage from tree or shrub removal can be repaired. 

Disturbed soil around the pond above the intended water line should also be prepared for mulching and seeding. Wheat can be used hold soil until perennial grasses can be sown. 

Once the pond refills, the back side of the dam should be checked for wet spots indicating seepage or leaks. Deep cracks left from the drought, root tunnels or pond seal damage from the renovation can be sources of pond leakage. There is an MU guidesheet, G1555 on reducing pond seepage.

Additional information on ponds can be found from the Missouri Department of Conservation and from the “Pond Management Resources on the Internet” web page.

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