What term describes water flowing over land that carries pollutants into waterways?

• A. Groundwater
• B. Leachate
• C. Watershed
• D. Runoff

Answer: (D)

This item tests the concept of surface water movement and how pollutants are transported to waterways. Runoff is water from precipitation that flows over the land surface instead of soaking into the ground. As it moves, it picks up pollutants such as oil, pesticides, fertilizers, and litter, and carries them into streams, rivers, and lakes.

Groundwater refers to water stored and moving through the soil below the surface, not the overland flow that carries pollutants. Leachate is the liquid that percolates through waste in landfills and can contaminate groundwater, but it isn’t the general overland flow that transports pollutants to surface waters. A watershed (drainage basin) is the land area where all the water drains to a common outlet, not the process of water movement itself.