Natural Sources: Understanding What Doesn't Pollute Our Water

Water pollution is caused by many different sources, including bacteria, viruses, fertilisers, pesticides, phosphates, plastics, faecal waste, nitrates, radioactive substances, oil spills, and agricultural or stormwater runoff. However, water and oil do not mix, and oil does not dissolve in water. Therefore, large oil spills and oil leaks, while often accidental, are not a source of water pollution.

Agricultural storm water discharges

Nonpoint source pollution is contamination derived from diffuse sources, such as agricultural or stormwater runoff or debris blown into waterways from land. It is the leading cause of water pollution in U.S. waters, but it’s difficult to regulate, since there’s no single, identifiable culprit.

Agricultural activities can contribute to water pollution through the use of chemicals and pesticides, which can seep into the groundwater and harm animals, plants, and humans. However, agricultural storm water discharges themselves are not considered a point source of pollution and are therefore excluded from certain regulations.

It's important to note that while agricultural storm water discharges are not considered a point source of pollution, they can still have harmful effects on drinking water supplies, recreation, fisheries, and wildlife. Therefore, it's crucial to manage and regulate agricultural practices to minimize their impact on water quality.

In summary, agricultural storm water discharges are not a point source of water pollution, but they can still contribute to nonpoint source pollution and have negative impacts on water quality. By understanding the differences between point and nonpoint sources of pollution, we can better target our efforts to protect and preserve our water resources.

Return flows from irrigated agriculture

Nonpoint source pollution, which includes return flows from irrigated agriculture, is contamination derived from diffuse sources such as agricultural or stormwater runoff or debris blown into waterways from land. It is the leading cause of water pollution in U.S. waters, but it’s difficult to regulate, since there’s no single, identifiable culprit.

The EPA regulates point source pollution by establishing limits on what can be discharged by a facility directly into a body of water. While point source pollution originates from a specific place, it can affect miles of waterways and ocean. Nonpoint source pollution, on the other hand, is contamination derived from diffuse sources and is the leading remaining cause of water quality problems.

Debris blown into waterways from land

Nonpoint source pollution is a leading cause of water pollution in the U.S. It is contamination derived from diffuse sources and includes agricultural or stormwater runoff or debris blown into waterways from land.

Nonpoint source pollution is difficult to regulate because there is no single, identifiable culprit. It is often caused by human activity and its consequences, such as rising global temperatures caused by CO2 emissions that heat the water and reduce its oxygen content.

The term "nonpoint source" is defined to mean any source of water pollution that does not meet the legal definition of "point source" in section 502(14) of the Clean Water Act. The term "point source" means any discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, or vessel or other floating craft, from which pollutants are or may be discharged.

Nonpoint source pollution is the leading remaining cause of water quality problems. The effects of nonpoint source pollutants on specific waters vary and may not always be fully assessed. However, we know that these pollutants have harmful effects on drinking water supplies, recreation, fisheries and wildlife.

The EPA regulates point source pollution by establishing limits on what can be discharged by a facility directly into a body of water. While point source pollution originates from a specific place, it can affect miles of waterways and ocean.

Oil spills and leaks

Oil does not dissolve in water, and large oil spills and oil leaks can have harmful effects on drinking water supplies, recreation, fisheries and wildlife.

Mercury from the Earth's crust

Mercury is a pollutant that can be found in oceans, rivers, lakes, canals, and reservoirs. It is sometimes caused by nature, such as when mercury filters from the Earth's crust.

Mercury is a heavy metal that can be toxic to humans and animals. It can accumulate in the food chain and cause serious health problems.

The main water pollutants include bacteria, viruses, parasites, fertilisers, pesticides, pharmaceutical products, nitrates, phosphates, plastics, faecal waste and even radioactive substances. These substances do not always change the colour of the water, meaning that they are often invisible pollutants.

Nonpoint source pollution is the leading cause of water pollution in U.S. waters, but it’s difficult to regulate, since there’s no single, identifiable culprit.

Oil spills and oil leaks are a major cause of water pollution. Leaks and spills often are caused by oil drilling operations in the ocean or ships that transport oil.

Frequently asked questions