What is the purpose of preventing runoff from septic tanks and leach fields?

The primary purpose of preventing runoff from septic tanks and leach fields is to ensure that contaminants do not enter the environment, which is crucial for maintaining the health of surrounding water bodies, including lakes, streams, and groundwater. This goal aligns closely with the intention behind option A, which emphasizes the importance of clean bathing water. Runoff from septic systems can carry pathogens and nutrients that deteriorate water quality, thus potentially posing health risks to humans engaging in recreational activities in water.

Controlling runoff also serves to protect groundwater by preventing the introduction of pollutants that could compromise drinking water supplies. This relates to option C, as proper management of septic systems can also support sustainable groundwater recharge processes by ensuring that treated effluent percolates effectively into the ground.

Furthermore, preventing nutrient-rich runoff directly contributes to mitigating algal blooms, which is the focus of option D. Algal blooms can result from excess nitrogen and phosphorus entering water bodies—nutrients that can escape from improperly managed septic systems.

In summary, while option B discusses fertilizer runoff, the more comprehensive understanding of the question's context reflects that preventing runoff from septic systems is vital for health, groundwater safety, and environmental balance, which encompasses the broader implications of options A, C, and D.