Polluted stormwater runoff generally happens anywhere people use or alter the land. People going about their daily lives are the number one source of stormwater pollutants. Most people are unaware of how they impact water quality. Some common examples include:
- Excessive pesticide use
- Letting oil drip out of their vehicles and littering
- Not picking up pet waste
- Over fertilizing lawns
- Using salt or fertilizer to de-ice driveways
Developed areas in general, with their increased runoff, concentrated numbers of people and animals, construction and other activities, are a major contributor to nonpoint source pollution, as are agricultural activities. Other contributors include forest harvesting activities, roadways, and malfunctioning septic systems.