Which of the following is NOT a source of groundwater contamination?

Natural springs are indeed not a source of groundwater contamination. Instead, they are typically sites where groundwater naturally seeps to the surface, often providing clean and filtered water due to the natural geological and biological processes that take place underground.

Groundwater can become contaminated from various human activities and certain materials or structures, such as pesticides and herbicides used in agriculture, sewers and septic tanks that can leak pollutants, and gasoline tanks which can corrode and release harmful substances into the groundwater. These options represent significant risks to groundwater quality due to their potential to introduce hazardous materials into the aquifer systems. In contrast, natural springs function as sources of relatively pure groundwater, highlighting the importance of protecting watersheds and the natural hydrologic cycle from pollution.