Stormwater run-off, anything that goes onto the ground (and especially paved surfaces) eventually ends up into the water cycle. Let's say 10 cars are leaking oi

Stormwater run-off, anything that goes onto the ground (and especially paved surfaces) eventually ends up into the water cycle. Let's say 10 cars are leaking oil in their parking spot. That oil gets washed away by the rain and ends up in the local waterways.