The correct answer is based on the regulations set forth to protect public health and groundwater quality. The minimum distance of 500 feet between feedlots, sewage treatment plants, and landfills from a public well is established to reduce the risk of contamination from these facilities.
These types of facilities can potentially release pollutants such as pathogens, nutrients, and chemicals into the environment, which can then migrate into the groundwater. By maintaining a buffer zone of 500 feet, the likelihood of contaminants reaching the well water supply is minimized, thus safeguarding the water that communities rely on for drinking and other uses.
This distance is a crucial aspect of water quality management and signifies a careful consideration of public health in the regulation of facilities that could adversely impact water resources. The other distance options do not reflect the level of protection deemed necessary to ensure that well water remains uncontaminated by potential pollutants associated with these types of operations.