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How Aeration Improves Water Quality

Aeration helps prevent taste and odour problems by ensuring that oxygen concentrations remain high enough throughout the entire water column to prevent conditions of little or no oxygen (anaerobic). Aeration also helps prevent the release of phosphorus from sediments. This limits algae growth and reduces the amount of plant material present to ultimately die and decompose.

Aeration prevents the release of iron from the sediments and the problems associated with high iron concentrations such as damage to water treatment systems, water distribution systems and drip irrigation systems.

Artificial aeration augments the natural process of oxygen replacement. This is accomplished by injecting air into the deepest part of the dugout producing a non-turbulent mixing action; lifting the oxygen-depleted water from the bottom to the top to circulate with the oxygenated water.

In the summer, warm temperatures produce very high levels of biological activity, resulting in increased oxygen demands. The rate of oxygen diffusion cannot keep up with the rate of oxygen consumption. This results in the quick depletion of oxygen levels in the water. This occurs most frequently when warm temperatures produce very high levels of biological activity which can very rapidly consume the oxygen.

This is the most common cause of summer fish kills in dugouts and lakes.

In the winter, once ice forms on a dugout it seals the surface and prevents very little new oxygen from diffusing into the water. Under these sealed conditions, algae decay quickly consuming any available oxygen.

Once oxygen levels become low, anaerobic organisms take over the decomposition process resulting in the release of unpleasant smelling gases such as methane and hydrogen sulfide.

The absence of oxygen in the water also allows plant nutrients (nitrogen, phosphorus) and metals (iron, manganese) trapped in the dugout sediment to dissolve into the water. A layer of poor quality water that is high in nutrients and metals begins to form at the bottom of dugout. As long as anaerobic conditions exist, the amount of poor quality water grows quickly and moves upward.

In the summer, anaerobic conditions may go undetected if water intake is near the surface of the water. However water conditions near the bottom of the dugout may be anaerobic. In the winter, anaerobic conditions are present when the water turns black (may be caused by dissolved iron, manganese and other dissolved or decomposed material) and has a rotten egg smell (caused by hydrogen sulfide gas).

Typical Winter Dugout Water Quality
Parameter (mg/L) Aerated Non-Aerated
Dissolved Oxygen 14.3 0.4
Iron 0.04 1.5
Phosphorus 0.05 0.15

Continuous year round aeration produces the best water quality. In fact, data indicates that water quality continues to improve for up to five years after a continually operating aeration system is installed in a dugout.

Watch the dugout animation to better understand the annual cycling of oxygen and nutrients and learn how dugout aeration improves quality in reservoirs.

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