Which of the following is NOT typically a source of impairment in water?

A well-maintained wetland is considered a beneficial ecosystem that contributes positively to water quality rather than impairing it. Wetlands serve numerous critical functions, including natural filtration of pollutants, absorption of excess nutrients, and habitat provision for wildlife. They help regulate water flow, reduce flooding, and maintain biodiversity, making them essential for healthy aquatic environments.

In contrast, nutrients, acids, and pathogens can all contribute to water impairment. Excess nutrients from sources like agricultural runoff can lead to algal blooms, which deplete oxygen in water and harm aquatic life. Acids can lower pH levels in water bodies, affecting the survival of many species. Pathogens, often stemming from contaminated runoff, pose health risks to humans and wildlife. Hence, while the other choices represent various forms of contaminants or environmental stressors, a well-maintained wetland plays a protective and restorative role for surface water quality.