Is pond dredging the best way to clean and restore your pond?
It’s a simple and natural fact. Large ponds and lakes will fill in over time and in time, that grand old pond that once stayed clean and clear, now has algae or other problems. This process is known as eutrophication. One of the main causes of pond algae blooms is the build up of organic material, muck, and sludge at the bottom. Things like leaves and other stuff fall or get blown into the water and sink and erosion might also play a part.
Being made up of organic elements, most of this sediment is a lot like compost in a garden. We all know that you can get any plant to grow better with good nutrients and anything organic that’s breaking down, in soil or water, will improve the vitality of a plant. Good for vegetables, bad for algae unless you’re using it for bio-fuels.
This fact makes it pretty obvious why a pond owner would want to clean up the bottom of their water-filled basin.
There’s really two ways to do it. The first process would be to use beneficial bacteria, or microbes and enzymes, to help break this sludge down and in effect, eat it away. This is nature’s method of cleaning and it works very well, and quite safely, but it does take a fair amount of time. On average with proper aeration running to help these aerobic bugs do their work, one could reasonably expect 3 to 6 inches, and possibly more muck reduction in a six to eight month season.
The second option, and one that is much quicker although usually more expensive, is to dredge out the pond bottom. Dredging equipment can help make pond restoration a relatively quick task where a great deal of build up can be removed in one to several days of work.
Planning and using the best tools for the job is important, and it could be said that there is not a single solution for every pond. Let’s look at the most common approaches to pond dredging.
Mechanical Dredging Equipment
The mechanical approach to dredging will involve some form of equipment such as a clamshell bucket and crane, a dragline, which uses a bucket with holes in it which is dragged across the bottom, or excavator dredging that uses something like a backhoe device. Because fairly heavy equipment is used in all of these operations, rainy weather can affect work times.
Hydraulic Dredging Pumps
A hydraulic dredge will actually float on the surface of the water and uses a pipe to suck stuff off the pond bottom. It’s similar to a very big muck vac that will remove sediment with great precision. The waste material is routed far away from the pond and released through a discharge pipe.
Of the methods of hydraulic dredging used, the most common are the auger dredge, or some type of cutterhead dredge. These tend to be very efficient in terms of how much sediment they remove and how much manpower is needed to do the work.
Once the muck is removed all the wet sediment should be dewatered or dried out to allow for easier removal from the pond site or it can be used in the area for structuring the landscape surrounding the pond.
So What’s The Benefits And Risks?
The benefits of dredging a pond, as noted above, include a very rapid and efficient reduction of sedimentation build up which can lead to many water quality problems. It’s a very direct way to increase the depth of a pond and a necessary step in most large pond restorations.
Dredging is not without it’s risks however. In many cases the water in the pond will need to be drawndown, or lowered to allow easier access to the bottom. As digging begins there is a good chance that bottom sediment may be disturbed enough to affect the ecology of the pond. Fish breeding and feeding habitat can be altered enough to affect populations negatively. And finally, additional nutrient rich sludge can be released and circulated, which can rapidly lower oxygen levels in the water. To guard against this it’s advised to use a quality aeration system in the pond during excavation as well as after the restoration is complete.
All in all, pond dredging may be the best solution for restoration of a natural setting. It’s not without it’s risks or costs, but it has proven to be the most efficient way to return a pond to a more youthful condition.