What is a common characteristic of surface water sources?

Surface water sources, such as rivers, lakes, and streams, are characterized by their direct exposure to environmental elements and human activities. This exposure means that surface water can be influenced by pollutants, sediments, and other contaminants introduced by natural processes or human actions, such as agriculture, industrial discharge, and urban development. This susceptibility to a wide range of environmental factors highlights the need for careful monitoring and management to ensure water quality and safety.

In contrast, being covered or shielded from environmental impacts—like option A—does not apply to surface water sources, as they are inherently exposed to the elements. Furthermore, surface water is not found underground, which makes option B inaccurate because underground water sources are classified as groundwater. Lastly, it is essential to treat surface water before consumption due to the potential contaminants it may contain, so option D is incorrect as well. Therefore, the characteristic of being directly impacted by environmental and human activities distinctly defines surface water sources.