Clean-outs: Is 2020 Pond Start-over Time?

The start of a new decade suggests renewals in all things, including ponds. And with ponds, renewal often means clean-outs. 

Perhaps you’re been thinking your pond might need a clean-out due to a number of factors: loss of depth, overgrowth of unwanted rooted vegetation, algae problems, nuisance fish or other aquatic critters, low oxygen, overgrowth in feeder and spillway streams, etc.

It’s not unusual for a pond to require a clean-out for those issues, especially after decades of use. Perhaps the pond has benefitted from clean-outs in the past, and might be due again; perhaps it’s due one for the first time. 

How do you know your pond might need a clean-out? And what are the best clean-out options?

Knowing When It’s Time 

Serious submerged and emergent aquatic weed and plant trouble suggests possible need for  clean-out. Aquatic weeds in deep water can interfere with swimming and fishing. Shoreline weeds can also interfere with swimming and boating and fishing, as well as encourage algae; create mosquito breeding areas. Supply muskrat food. Edge plants that often cause problems are cattails and rushes.

Types of Clean-outs - Weeds

Weeds in deep water may be removed by cutting. This can be done in a variety of ways: using long handle cutting rakes, from shore or boat; hand pulling or cutting by snorkle or scuba divers; vacuum suction pumping often operated by a diver; special weed cutting boats; and finally pinpoint or full pond clean-out by excavator and/or dozer, maybe a dragline.

Many clean-out tactics will be aided by a partial drop of the pond water level, improving access to troubled areas like the shoreline; or complete dewatering for access to the entire pond bed, as well as reduction of water content in material to be removed.

Depth Restoration

Loss of depth is often encountered in older ponds, or ponds that weren’t dug properly deep to begin with. The remedy is a clean-out, often by excavation. Or possibly suction dredging or aeration.

How do you know your pond may be too shallow? A healthy pond will be about six feet or deeper, depending on your region and fish you raise. In Vermont, eight feet or more is considered good, 10 ft plus even better. Over the years even a well-made pond can lose depth to sediment build up from eroding supply inflows and general runoff; and buildup of organic matter (plants, algae, fish food and waste, etc.). If shallowness is a concern, measure pond depths throughout the pond, and sample sediment to see if it’s organic matter vs. minerals like sand and gravel. This will help determine best clean-out strategy.

Regaining depth by some type of clean-out will help the pond in several ways. Deeper water tends to stay cooler, which is good for fish; better oxygen content, which is good for fish and decomposition of organic matter; less nutrients for unwanted plant and algae growth; less sunlight penetration to the pond bed and thus less photosynthesis of unwanted plant growth.

Again, clean-out and depth improvement can be done with physical removal by machines like excavators and suction pumps; and sometimes by aeration, enhancing decomposition of organic sediments. 

Critters

Because the most efficient clean-outs by excavator usually work best in a dewatered pond, there may be loss of aquatic critters: fish especially. Owners may fish or net out fish before dewatering. As for frogs, salamanders, and other pond dwellers, many will leave pond during a slow drawdown. But if you have unwanted fish a drawdown can help gather them for removal, or cut down the population. Many aquatic critters will survive by burrowing in the mud. 

(If you are trying to reduce crayfish, another removal method is to add bass to the full pond to hoover them up. As for leeches, a clean-out may help reduce the population, but a replacement community often remains, and removal requires other methods.)

If you hire people or machines to do a clean-out, make sure equipment and swimmer gear is free of plants from their previous visits. I’ve seen pond clean-outs produce subsequent invasive growth due to imported seeds and plant fragments.

If done properly, a pond clean-out is like getting a new pond. Great start for the new decade!