Which of the following is NOT considered a point source discharge?

A point source discharge is defined as a single, identifiable source of pollution that discharges pollutants directly into a water body. Wastewater treatment plants and combined sewer overflows are typically classified as point sources because they have specific outfalls where wastewater is released. They are regulated under the National Pollutant Discharge Elimination System (NPDES) and have identifiable discharge points.

In contrast, septic tanks are typically considered non-point sources of pollution since they are distributed over a wide area rather than concentrated at a single discharge point. The effluent from septic tanks can seep into the ground or surface waters more diffusely rather than through a discrete, defined outlet. This distinction makes septic tanks less easily regulated than point sources, as they can contribute to water quality issues without a specific point of discharge.

Thus, the classification of septic tanks as non-point sources supports the assertion that they do not fit the definition of point source discharges, affirming their status as the correct answer in this case.