Build up of organic sediment or muck is common in many aquatic bodies. This is mostly due to water runoff containing fertilizers, grass clippings, leaves, animal waste, septic waste, etc. Aquatic weeds, dead algae, dust, pollen, and fish and waterfowl droppings are also contributors. Muck removal is the foremost and necessary step towards a clean lake bottom or pond bottom. When oxygen is depleted in a water body, anaerobic bacteria partially break down organic matter in the sediment. In the process, they produce hydrogen sulfide. Hydrogen sulfide is the “rotten egg” smell present when you stir up the muck in most lakes or ponds. The cause of the odor is a lack of oxygen. Hydrogen sulfide is not only highly toxic to aerobic bacteria; hydrogen sulfide is also toxic to insects, and is toxic to fish. Anaerobic bacteria also release ammonia into the water column. Ammonia has an unpleasant smell and is toxic to fish. So the causes of organic sediment (muck) accumulation, unpleasant odor and fish kills in lakes are a lack of oxygen and high levels of toxic gases. The presence of muck or a rotten egg smell is a sign that the bottom is lacking in oxygen and the lake bottom needs Aquakler.