runoff

ot noun

1. Dissolved chemicals, etc, included in such water. The runoff of nitrates is poisoning the lake.
2. A second or further round of an indecisive election, after other candidates (often all but the last two) have been eliminated. There will now be a runoff as neither front runner received more than 50% of the vote.
3. That portion of precipitation or irrigation on an area which does not infiltrate or evaporate, but instead is discharged from the area.