You may be surprised to know that animals pollute also. Dog waste in the street can be carried by runoff water. Usually bacteria are removed as water passes through soil because it acts as a filter. Some parking spaces have oily stains from cars. Most of the water that falls on this parking lot ends up in a catch basin.
Motor oil leaking from a car is a mixture of many different organic compounds and heavy metals.
Many are toxic or can cause cancer. Storm water drain from parking lot opening into stream valley shown on right. This parking lot is slightly lower in elevation than the surrounding area. In the woods, you can see a storm water drain which feeds the beginning of this stream. The engineers who designed the storm sewer system used the abandoned stream valley as part of the runoff system for storm water.