What type of pond or lagoon should be used only as a last resort when disposing of wastewater?

The type of pond or lagoon that should be used only as a last resort for disposing of wastewater is the evaporation lagoon. Evaporation lagoons operate by using heat from the sun to facilitate the evaporation of water, which concentrates the pollutants in the remaining sludge. This method is often employed in areas with low rainfall and high temperatures, making evaporation a feasible option. However, it has significant limitations, including the risk of contaminating the surrounding environment if not managed properly.

Using evaporation lagoons should be approached with caution because they do not treat wastewater in the conventional sense, as they primarily remove water while leaving contaminants behind. Therefore, they might not meet regulatory standards or public health requirements if alternatives are available. Other methods of wastewater treatment such as aerated, oxidation, or non-aerated ponds usually provide better and more effective means of managing wastewater. Because of these factors, evaporation lagoons are typically considered a last resort option.