What is the primary environmental concern with nonpoint source pollution?

Nonpoint source pollution is primarily concerning because it originates from many diffuse sources rather than a single, identifiable point. This type of pollution is often the result of runoff from rainfall or snowmelt that carries pollutants such as fertilizers, pesticides, sediment, and oil from multiple locations across landscapes like agricultural fields, urban areas, and rural lands.

Because these pollutants accumulate from various sources and are transported over broad areas, it becomes challenging to pinpoint an exact source of contamination. This complexity makes regulation and management of nonpoint source pollution difficult compared to point source pollution, which can be directly controlled and managed at a singular location. Additionally, this type of pollution often impacts both surface and groundwater, adding to its widespread environmental implications.

The other options do not accurately capture the essence of nonpoint source pollution. It is not easily identifiable or regulated, as stated in the first choice, nor is it limited to urban areas. Furthermore, while it can affect surface water, it can also impact groundwater, which makes the fourth choice incorrect as well.