What is least likely to be an issue in contaminating a well?

The option referring to distance from nearby lakes and streams is least likely to be an issue in contaminating a well because, generally, the risk of contamination from lakes and streams declines with increased distance. Water bodies can indeed introduce contaminants, but if a well is situated a significant distance away from these natural sources, the likelihood of contaminants reaching the well decreases.

In contrast, proximity to industrial sites, agricultural runoff, and the presence of septic systems are directly associated with potential contaminants. Industrial sites may release chemicals, agricultural activities can introduce fertilizers and pesticides, and septic systems can lead to the introduction of pathogens and nutrients into groundwater if they are not properly managed or located. Thus, being close to these sources presents a greater risk of well contamination compared to the relatively neutral impact of distance from lakes and streams.