Introduction to Point Source Pollution

Under the Clean Water Act, all point source discharges of pollution require a permit. This basic principle is the foundation of water pollution prevention and control in the United States. Generally, anyone who discharges pollutants [of significant volume or taxicity] from a point source without a Clean Water Act permit breaks the law. There is, of course, a corollary: It is perfectly legal to discharge pollutants, if you have a valid permit and comply with its terms. Understanding how the permitting system works is critical for anyone wanting to use the Clean Water Act. Citizen involvement is important in all phases of the permit process.You don’t have to be a lawyer to make a difference, but you do need to understand the system’s basics. By developing a solid grasp of the following terms and concepts, you will be much better able to help prevent and control water pollution in your watershed.

What is a "point source?"

The Clean Water Act’s primary point source control program is the National Pollutant Discharge Elimination System (NPDES). This system rests on the definition of point source: “any discernible, confined, and discrete conveyance” of pollutants to a water body. The definition of discrete conveyance includes, but is not limited to, “any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, landfill leachate collection system, vessel or other floating craft from which pollutants are or may be discharged.”

As we will see, the definition of point source covers a wide and expanding variety of activities, beginning with direct discharges from factories and sewage treatment plants, and extending to a multitude of other sources. (The Act provides one major exception to the point source definition: it specifically excludes “return flows from irrigated agriculture or agricultural storm water runoff.” (40CFR122.3) This exempts many but by no means all agricultural activities from the NPDES program.)

Over the years, the EPA has included more sources under its definition of point source pollution. These sources are now regulated under the NPDES program.

For example, in the early years of the Act, most agencies considered municipal stormwater pollution, or “urban runoff,” as an unregulated, nonpoint source, even though it is responsible for many of our nation’s most severe water quality problems.Much of it is collected in and discharged through stormwater pipes — clearly, in Clean Water Act parlance, “discrete conveyances.” The recognition of this fact has led to programs to control many forms of urban runoff by bringing them under the NPDES umbrella. 

What is a "nonpoint source" of pollution?

The term “nonpoint source pollution” has been used in many different ways in many different contexts over the past twenty-five years. Some define it as “polluted runoff from rain or snow,” others as pollution from “diffuse sources,” and still others, colorfully, as “poison runoff.”

When all is said and done, the most accurate, complete, and enduring definition of the term is the very simplest. A “nonpoint source” is exactly what the words say: Any source of pollution that is not a point source.

How has NPDES worked so far? Is it actually eliminating pollution?

The NPDES has greatly reduced the impact of many existing discharges, but it certainly has not eliminated pointsource water pollution in the United States. In fact, while most pre-existing pollution discharges have come under greater control since the Act was passed, with some now approaching “zero impact” quality, few have actually been phased out. Moreover, thousands upon thousands of new discharges — including many with significant impact — have been permitted.

The NPDES performs admirably in those places where a well-informed public keeps an eye on Clean Water Act goals, monitors watershed activities, understands how the NPDES and other CWA tools are supposed to work together, and plays an active role in their ongoing implementation. In the absence of an ever-vigilant public, however, the NPDES can produce results that are quite the opposite of those intended.

Does the NPDES program address nonpoint source pollution?

Yes, it can. As described above, nonpoint source pollution is used to describe many non-discrete methods of conveyance of pollution into a waterway, such as the water that flows over our city streets and agricultural fields. The Clean Water Act allowed for regulation of that type of pollution when it ends up in a ditch or a pipe. That is why we discuss stormwater pollution as a point source, because most of it is collected by the stormdrains, gutters or ditches and sent either through the treatment plants (if the system is combined with the sanitary system) or out to the waters directly.

There are ways that nonpoint source pollution, which is otherwise unregulated, can be addressed by NPDES permit conditions. For example, certain management practices (revegetation) can be required onsite that improve receiving water health.

We are also seeing another strategy, pollution trading, occasionally built into NPDES permits in order to address nonpoint source pollution. Trading is usually associated with watershed restoration plans or TMDLs.

				Next: What do permits contain?