What is the impact of high BOD levels on a water body?

High levels of Biochemical Oxygen Demand (BOD) in a water body indicate a significant amount of organic matter present that bacteria can decompose. The decomposition process consumes dissolved oxygen in the water, which is essential for the survival of aquatic organisms such as fish and invertebrates. When the oxygen levels are depleted due to high BOD, it can lead to a condition known as hypoxia, where there is insufficient oxygen to support aquatic life. This can result in stress or even mortality of these organisms, impacting the overall health and biodiversity of the aquatic ecosystem. Therefore, the correct answer highlights the negative consequence of high BOD levels, which is a critical concern in wastewater management and environmental protection efforts.