What is a negative consequence of stormwater runoff on surface water quality?

Stormwater runoff significantly impacts surface water quality, and one of the most pressing negative consequences is the introduction of pollutants like oil and heavy metals into water bodies. When rainwater flows over urban surfaces such as roads, parking lots, and industrial sites, it picks up various contaminants. For instance, oil spills from vehicles and runoff from industrial activities can lead to elevated levels of hydrocarbons in nearby streams, lakes, or rivers.

Similarly, heavy metals such as lead, cadmium, and zinc can wash off from building materials, vehicle emissions, and road surfaces. Once these pollutants enter the aquatic environment, they can cause a range of ecological problems, including toxicity to aquatic organisms, bioaccumulation in food webs, and impairment of water quality for drinking and recreational use.

Unlike the other options, which either do not accurately represent the impacts of stormwater runoff or imply positive outcomes, the introduction of pollutants illustrates a clear and well-documented consequence of this phenomenon.