Which type of pollution is associated with agricultural runoff and urban stormwater?

• A. Point source pollution
• B. Groundwater contamination
• C. Nonpoint source pollution
• D. Atmospheric deposition

Answer: (C)

Nonpoint source pollution arises from many diffuse sources rather than a single outflow. When rain falls or irrigation water runs over agricultural fields, lawns, streets, and other surfaces, it picks up nutrients like nitrogen and phosphorus, pesticides, sediments, oils, and metals. This polluted water then drains into streams and lakes, carrying contaminants from numerous locations across the landscape. That makes agricultural runoff and urban stormwater classic examples, because there isn’t one identifiable discharge point—the pollution comes from across a watershed. By contrast, point source pollution comes from a discrete outlet such as a pipe or plant, groundwater contamination involves pollutants moving through the subsurface, and atmospheric deposition involves pollutants delivered from the air.