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What happens when a pond get’s “old and is dying”? What can be done to save it or restore it back to what it once was?
Todays Q & A comes to us from Janet that sent us a link to an interesting article from Sag Harbor News. It seems that Mill Pond, an old and well established lake in the NE United States is in very bad shape. You can read more about this unfortunate situation through this news report.
Answer: Thank you for the link and for your question Janet. It’s inevitable that every pond will age and unfortunately part of that process is a natural “filling in” of the pond basin with all kinds of things. Sediment, blown in debris, shore erosion, the growth and die-off of plants like algae and aquatic weeds, organic material like leaves…they all add up to a pond that is in a state of degradation.
As I’ve often told many large pond owners, the number one goal that you have is to slow this filling in down as much as possible. Some of this may come from proper design considerations but even with this, nature will run it’s course.
Organic build up at the bottom will eventually lead to very high nutrient loading in the water, and like any decaying material, it will serve to create a nutrient density (high phosphates are one component) that is sure to help other aquatic plants grow prolifically. Nutrient spikes can also come from run off from highly fertilized ground around the pond. Algae blooms are fed by these things, and as algae is killed or dies off, it too will add to the organic build up. Nature has a way of dealing this mucky build up, namely naturally occurring beneficial bacteria. But if conditions don’t exist for this to be optimized, then the biological activity simply can’t keep up and the pond keeps filling in at an accelerated rate.
I personally don’t know the history, or the size of Mill Pond but in most cases, you would want to optimize the restoration capabilities of the pond itself. Dissolved oxygen levels should be checked at various points in the pond to make sure they are adequate to support aerobic bacteria. This is particularly important near the bottom where oxygen levels are normally lower. If the readings show a deficiency then some form of bottom based aeration should be installed to improve the condition if it’s feasible to do so.
Along with that, you’ll find that mineral supplementation was mentioned. Interestingly, if a pond has very soft water with low mineral content, and in particular low calcium levels, the natural bacteria will not have the raw material needed to bind to the phosphates and neutralize them.
If algae is a continual problem, chemicals should not be used to control it. Most algaecides contain some level of copper which although it’s toxic to algae, it’s also detrimental to good bacteria, and this is essential to maintain as it’s really the most powerful pond restoration device that’s available. For immediate, non-chemical algae control, it might be possible to limit it’s growth with the bacteria and aeration alone, however if more help is needed, new technology like ultrasound may also be useful to test out.
As the article states, this approach has never been a quick fix to a problem that has developed over many years, however it is the best hope for the pond to be restored to a healthier condition. The good news is that if the proper resources are available and some consistency is applied in the management of the pond, there is ample evidence that the pond can be afforded a new life as a cleaner and clearer body of water.
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