1. The disgusting water that flows into the ocean after a rain storm. Urban runoff is nasty and polluted water that gains momentum in urban cities then makes its way to the ocean. It will most likely get you sick if swallowed, and should be avoided at all costs. Surfing or other ocean sports are usually avoided after urban runoff for fear of getting some kind of disease, infection or other illness.
Surfer Bro: Dude, I can't bro-out with you tonight, I got sick from surfing yesterday; there was too much urban runoff.
by CreepingDragon October 20, 2009