In this post I will review the issue of Dredging. This will be a high-level overview of the topic. If you desire more depth (pun intended) a Google search will open your eyes and mind to plenty of additional material.
If you have lived on the pond for any length of time you have propbably heard local “legends” of the US Army Corps of Engineers being contacted to drain the pond, remove all the rich topsoil (muck) from the bottom to a) restore the depth of the water, 2) establish a sandy bottom and, 3) sell off this loam for millions upon millions of dollars. For what it is worth, I have never met anyone who has been able to substantiate this proposal as fact.
At it’s core, dredging is an excavation and removal process. Imagine site prep being done for a house lot. The land is scraped clean with all the loam being piled in a corner of the lot. Much will be saved to recover the lot after the house is built, and some may be sold off.
This is much more complex when the land is under several feet of water. The most effective dredging operation requires the body of water to be drained before the bottom can be scraped. You can imagine with a pond of about 80 acres this would be expensive. It would also have a potentially devastating short-term impact upon fish and wildlife.
Even if these were not obstacles, such an operation requires approval and cooperation of local, state and federal agencies. However, it is worth noting that other Massachusetts communities have successfully done this in recent years.
Another method involves suction. A high-powered vacuum-styled device draws out the muck as a slurry and the water is drained off, reserving the soil. The drawback with this method is that the fine sediment is whipped up and is suspended in the water, again with a severe impact upon fish and game.
When Domenic Meringolo met with us he admitted that dredging is the only method available to us with long-term impact. The lasting benefits are likley another century and a half of improved water depths, reduced muck and the pleasure of a sandy bottom to many areas of the pond.
However, high costs, extensive permitting at all levels of government and a dramatic short-term environmental impact certainly limit this as a viable option for cleaning up Flannagan Pond.
Before I sign off for this post, I want to show a video example of suction dredging.
In my next installment I will discuss various Vegetation Management Alternatives.