Where do Contaminants Come From?
Contaminants enter the environment in many different ways; disposal of municipal wastes, factory discharges, and oil or chemical spills are a few examples. These examples are considered forms of “point source” (or “end of the pipe”) pollution because their origin is easily recognized. In many cases, the origin of pollution may not be as clear. For example, agricultural pesticides can be carried by runoff, or enter an aquifer, and end up contaminating a stream dozens of miles away. Pollutants can also be carried for long distances through the air and deposited on land and in water by rain. Such examples are called “non-point source” pollution. Pollution from non-point sources can contaminate areas that may appear to be relatively untouched. For example, 41 of our nation’s Fish and Wildlife Service management units (national wildlife refuges, waterfowl production areas, etc.) have advisories against consumption of fish, shellfish, or other wildlife, and a number of our national wildlife
