Lake and Pond Dredging in Tennessee: Hydraulic versus Excavation

If you own a lake or pond, dredging is in your future. Dredging is not an optional action when it comes to lake and pond management: if you own the water body long enough, you’re going to need to dredge it. Some lake management companies operating in Tennessee advertise hydraulic dredging services; our company does dredging the old-fashioned way, with conventional excavation equipment. Let’s dive into the differences between the two methods.

Dredging is necessary because all lakes and ponds accumulate silt and muck over time. This layer of sludge will increase in depth year by year, and as it increases, it wields an ever-larger impact on every facet of your lake or pond, from aesthetics to weed control to the fishery. Organic muck is rich in phosphorus, which means that as that layer of sludge at the bottom of your prized water feature takes up an ever-larger slice of your pond or lake’s depth pie, issues with excess weedgrowth become more pronounced. Phosphorus is a primary food of all plants, so more muck equals more plants. Aquatic plants in moderation are great habitat for fish; in excess, they can make it difficult to fish, cause oxygen depletion problems, and compromise the aesthetics of the lake or pond. Die-hard fishermen may love seeing bank-to-bank weedgrowth; most lake and pond owners will not.

Muck not only leads to excess weedgrowth; it also compromises water quality by releasing noxious gases into the water and lowering dissolved oxygen content. A heavy accumulation of muck can lead to overly robust phytoplankton blooms, which in turn can lead to fish kills via oxygen depletion. A normal phytoplankton bloom is desirable in a lake or pond where the fish are a priority; when the bloom reaches a visibility level of less than fifteen inches, there is a constant threat of a fish kill. Phytoplankton emit oxygen during daylight hours in the process of photosynthesis; at nighttime phytoplankton, like all other plants, go into respiration, whereby they remove oxygen from the water. More phytoplankton means more oxygen being removed at once, which is why a very dense bloom can cause a fish kill. Cyanobacteria, also known as blue-green algae, occurs more commonly in older lakes and ponds with advanced sludge accumulation, and cyanobacteria can cause a fish kill at any time, in addition to being harmful to humans and pets.

Another way sludge accumulation harms a pond over time is even more basic: a pond that had adequate depth for a quality fishery when it was first built, can dip below the threshold of what it takes to sustain healthy fish as the sludge cuts more and more into the average and deepest depths. Muck, because it is not completely solid, will always concentrate in the deepest areas of the lake or pond,

so whereever your best depth in the lake is, you can count on losing that valuable depth first. Very shallow lakes and ponds never produce quality fisheries. We have developed world-class fisheries in more than a couple ponds that were shallower than what is ideal; but there is a minimum depth that is necessary for fish to avoid thermal stress in the coldest periods of winter and hottest periods of summer, and once a lake fills in past that point, no amount of management will produce quality fishing until the depth is addressed.

Now to the two types of dredging available to lake and pond owners. Hydraulic dredging companies tout the fact that the lake or pond does not have to be drained to perform the service; this is the chief advantage of this style of dredging. If you have a relatively new pond and your fish are thriving, and you just want to knock back the muck slightly without overly impacting your fish, a hydraulic dredge may be a good option for you.

If, conversely, your lake or pond needs the real thing, exhaustive dredging that removes a significant portion of the total muck and silt accumulated at the bottom of your lake, hydraulic only makes sense if you enjoy paying ten times as much for a service as what another provider can offer. Hydraulic dredges pump sludge from your lake bottom into sediment de-watering bags; a typical bag size used for lake and pond dredging is 15’ X 15’; this size bag will hold 9.6 cubic yards of material. A typical hydraulic dredge of the size commonly used for private lakes and ponds will fill two to five of these bags per day, meaning in an eight-hour workday, one of these dredges can remove up to 48 cubic yards of sludge from your lake or pond.

Trophy Pond has dredged dozens of lakes and ponds. We use conventional excavation equipment, which means the lake or pond often needs to be at least partly drained. It isn’t necessary to completely drain the lake if, for example, the purpose of the dredging is to reduce muck in shallow areas so as to reduce concomitant weedgrowth. We also have done multiple dredging jobs where no draining whatsoever was done; these were ponds that had gone decades without dredging, and the landowner simply wanted to reduce the shallowest water around the edges of the pond as much as possible without draining so as to lessen weedgrowth, or to help the overall depth profile for the fish.

But if the goal is removal of most or all of the muck and sediment, that entails draining. If you have never owned a lake or pond that needed this level of dredging, you might object about losing the fish population; but lakes with this level of muck and sediment almost never have quality fisheries. We have never drained such a lake or pond and found trophy fish in it.

Now to the meat and potatoes of this comparison: good old-fashioned value, i.e. what you’re getting for your money.

Remember that average amount of sludge that a hydraulic dredge can remove in a day, up to 48 cubic yards? Conventional excavation equipment can remove that much in fifteen minutes.

One over-the-road triaxle dump truck holds 16 cubic yards of material. A good excavator operator can load such a dump truck in five minutes. When we do a dredging job where the landowner wants the material hauled offsite, we will have a few or several dump trucks on the job: the excavator operator loads one truck, that truck drives away from the pond edge, and another truck pulls into the spot it was just parked in and gets loaded; five minutes later that truck is pulling away to let another one get loaded. When we do a job where the landowner wants the material dumped somewhere on his property - muck makes the best crop fertilizer you’ll ever find - we use a 40-ton offroad dump truck that we own; that truck will hold 30 to 32 cubic yards per load. As in, if the site where we’re dumping the material is 300 yards away from the pond, in fifteen minutes we can remove 125% as much material from the pond as what a hydraulic dredge can do in eight hours. Several times, both with over-the-road trucks hauling to an offsite dump location and with an articulated dump truck hauling elsewhere on the landowner’s property, we have removed over 50 dump truck loads of material from a pond in one day. We dredged a four-acre pond in Franklin, Tennessee three years ago dumping the material 400 yards from the pond, and we had multiple days on that job where we removed over 50 truckloads in one day. That’s over 1,500 cubic yards in one day.

The last factor to consider is cost. We bid on a dredging job for a three-acre pond in Brentwood a couple years ago where the HOA had already received a bid for hydraulic dredging; the hydraulic bid came in at over a million dollars. We bid a fourth of that.