Walking in the pond will relate pretty quickly the depth of the layer of organic material on the pond bottom. Your feet will sink into a layer of black ooze. I'm guessing your pond likely has 12"+ layer. I have used both excavator and dozer on ponds at my place, depending on the nature of the pond bottom. Too much material and a dozer will get stuck, need long reach boom on excavator to remove in that case. I think it's a good idea to excavate if you are draining, get a new lease on life of the pond. If you do so, I would bet the duckweed would not find establishment easy with removal of nutrients. Clean slate for you, blank canvas.

Many men go fishing all of their lives without knowing that it is not fish they are after. ~ Henry David Thoreau

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