We found our 22-acre farm in Missouri through an auction notice—1883 Victorian farmhouse, barn, stocked pond and all. We were thrilled with the purchase, but when it came to the pond, the only things it was stocked with were cattails and bullfrogs. Created pre-1980, 20-plus years of silt build-up, burgeoning vegetation, and cattle wading into it to cool their hooves had rendered it little more than a shallow swamp that visiting ducks could scarcely navigate without tangling a foot in the weeds: a classic case of what Langston University Research and Extension in Oklahoma, calls “successional changes.”
Langston states that without human intervention, your pond will begin to shrink as years pass. The pond will become bog-like near the shore, as willows and other trees begin to line banks, their young seedlings and shoots advancing. Eventually, the pond will dry up, and you’ll be left with a cattail-filled swamp.
To Dredge or Not To Dredge?
Depending on water clarity, sunlight does not typically penetrate beyond 3 to 4 feet of water depth, which helps keep plant growth at bay. But as a pond undergoes succession, it becomes shallower, allowing all manner of vegetation to flourish and further contributing to silting and shallowness. Excessive muck on the bottom, caused by nutrients from runoff and decaying plants, can really only be dealt with through removal. If this describes your pond like it did ours, it may be time to dredge.
Dredging generally removes 2 to 5 feet of muck, reducing the nutrient base for excess vegetation and creating deeper water where sunlight cannot penetrate. If you’re wanting to stock a pond with fish, Michigan State Extension Service recommends dredging it to 15 feet or more to improve fish habitat. The possibility of recreational use, such as swimming or boating, is restored by dredging, as well, though it has to be done in a particular way to help an algae problem.
“If your pond has a firm bottom of sand, gravel, clay or bedrock, dredging the soft muck on top may provide you with greater depth, reduced nutrients for algae, and more oxygen,” according to the Wisconsin Department of Natural Resources. “However, if the pond is without a firm bottom, dredging will only deepen the pond and may even increase algae or aquatic plant problems by exposing bottom sediments that contain more available nutrients.”
Dredging also does not address excessive nutrient loading that often occurs from runoff. If you go to the expense of cleaning out your pond, it’s wise to investigate long-term pond management, including barriers for nutrient loading and wading cattle. In many cases, your local extension office can help you assess your pond and design a maintenance plan.
Choose Your Method
If you do the work yourself or can hire a neighbor with a bulldozer, as we did, you may be able to clean out your pond without exorbitant cost. However, depending on where you live, the size of your pond and where the sludge will be transferred, dredging can cost tens of thousands of dollars. Hiring a company with a floating rig that digs and pumps the debris into geo-bags for removal will, of course, be more expensive than a partial dredging, which only deepens shallow shoreline areas.
For DIYers, the cooperative extension at Virginia Tech/Virginia State University assures landowners that dredging a pond by hand is simple, economical and efficient compared to using a machine, though be forewarned: It’s no easy task. Some pond owners keep cattails and vegetation at bay by dragging a rake, cutter bar or line along the pond bottom, then disposing of all vegetation and debris they dislodge. (Neglecting this last step may lead to spreading rather than reducing the problem.)
Many farmers—us included—opt to drain the filled-in pond before dredging. Here’s the dredging method we used:
- Cut a channel to allow drainage. Doing this before the winter/spring rains arrive will give the pond all summer to dry out. Some ponds need a full year or more to become solid enough to support heavy equipment. Consult your local extension office for the norm for your area.
- Dredge the pond. Once the pond is dry, bulldoze down through sediment layers, removing dried muck and improving pond depth and contours, but take care not to disturb the base layer that enables the pond to hold water. Farmers use the removed dirt to reinforce and/or augment the current dam/dike, enrich gardens or other areas of the farm that can use the nutrient-rich soil, or spread it in an area that needs filling/leveling.
- Refill the pond. Once the pond is dredged to the desired depth, fill in drainage channel, and while you wait for the rainy season to fill it in, line out your long-term maintenance plan to keep your pond looking good!
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