Which of the following is NOT considered a point source of water pollution?

Which of the following is NOT considered a point source of water pollution?

• A. Industrial discharge pipe
• B. Urban stormwater runoff
• C. Agricultural runoff from a field
• D. Underground storage tank leakage

Answer: (B)

Distinguishing point sources from nonpoint sources is the key idea. A point source is a single, identifiable discharge that enters a water body from a definite outlet, like a pipe or a specific leak. An industrial discharge pipe is a classic point source because pollutants come from one clearly traceable outlet. An underground storage tank leakage is also a point source since the leak originates from a specific tank. Urban stormwater runoff, on the other hand, is not tied to one discharge point. Rainwater flows over many streets, parking lots, and lawns, picking up pollutants from numerous places and then entering waterways. That diffuse, landscape-wide origin makes it a nonpoint source of pollution. Agricultural runoff from a field is likewise nonpoint: it comes from widespread areas across the field and surrounding land rather than a single outlet.

Distinguishing point sources from nonpoint sources is the key idea. A point source is a single, identifiable discharge that enters a water body from a definite outlet, like a pipe or a specific leak. An industrial discharge pipe is a classic point source because pollutants come from one clearly traceable outlet. An underground storage tank leakage is also a point source since the leak originates from a specific tank.

Urban stormwater runoff, on the other hand, is not tied to one discharge point. Rainwater flows over many streets, parking lots, and lawns, picking up pollutants from numerous places and then entering waterways. That diffuse, landscape-wide origin makes it a nonpoint source of pollution.

Agricultural runoff from a field is likewise nonpoint: it comes from widespread areas across the field and surrounding land rather than a single outlet.