What is identified as the target pollutant in water quality criteria?

The target pollutant in water quality criteria is phosphorus. Phosphorus is a key nutrient that can lead to significant water quality issues, particularly in freshwater ecosystems where its excess can cause eutrophication. Eutrophication is a process that results in excessive growth of algae due to high nutrient levels, primarily phosphorus, which can deplete oxygen in the water, harm aquatic life, and affect water quality.

Phosphorus is often prioritized in water quality management because it is frequently the limiting nutrient in freshwater systems, meaning that its availability directly influences the growth of algae and aquatic plants. Efforts to manage phosphorus levels are integral to maintaining healthy water bodies, as excessive levels can lead to long-term ecological impacts.

While nitrogen, suspended solids, and heavy metals are also important pollutants in their own right and can contribute to water quality degradation, phosphorus specifically is often singled out due to its critical role in promoting the growth of harmful algal blooms and its significant impact on freshwater ecosystems. In many regulatory frameworks and water quality criteria, phosphorus is carefully monitored and regulated to protect aquatic environments.