Which of the following is more closely related to water quality rather than water quantity?

The choice of sewage treatment facilities as more closely related to water quality is based on their purpose and function in relation to water systems. Sewage treatment facilities are designed to process wastewater and remove pollutants before the water is released back into the environment or reused. This treatment ensures that harmful substances, pathogens, and nutrients that could contaminate water bodies are significantly reduced, thereby improving the overall quality of water.

In contrast, the other options primarily focus on the amount of water rather than its quality. For instance, depletion of aquifers relates to the reduction of groundwater levels, which is a matter of quantity. Similarly, the construction of dams largely concerns the management and storage of water, affecting how much water is available in a given area. Crop irrigation is also focused on providing sufficient water for agricultural needs, which is again a matter of quantity rather than quality. Thus, sewage treatment facilities stand out as directly tied to enhancing water quality through the reduction of contaminants and the treatment of wastewater.