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2 Tutorials that teach Water Pollution: Point vs. Non-Point Source
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Water Pollution: Point vs. Non-Point Source

Water Pollution: Point vs. Non-Point Source

Author: Sophia Tutorial

Differentiate between point and non-point source water pollution.

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what's covered
This tutorial will cover the topic of water pollution. We will discuss the impacts and sources of water pollution, focusing on the two types of water pollution: point and non-point source. We will also cover several historical examples of water pollution.

Our discussion breaks down as follows:

  1. Impacts of Water Pollution
  2. Types of Water Pollution
    1. Point Source Water Pollution
    2. Non-Point Source Water Pollution
  3. Historical Examples of Water Pollution
    1. Camelford
    2. Jalisco
    3. Gulf of Mexico
    4. Chinese River Dolphin

1. Impacts of Water Pollution

Negative impacts of water pollution include:

  • Decreasing the amount of safe drinking water for human use
  • Increasing risk to human health, whether it be from consumption or recreation
  • Making organisms sick or killing them
  • Interfering with organisms, life cycles, or reproductive cycles
  • Altering species and disrupting the balance in an ecosystem

2. Types of Source Water Pollution

There are two main types of water pollution: point source water pollution and non-point source water pollution.

2a. Point Source Water Pollution
Point source pollution is more easily trackable and accountable because it is affixed. Examples of point source pollution would be:

  • Landfills
  • Polluted waste storage lagoons
  • Underground storage tanks
  • Septic tank systems
  • Municipal and industrial wastewater treatment plants
  • Ocean-linked dumping of waste is yet another point source pollutant.

Wastewater Treatment Plant
Wastewater Treatment Plant

2b. Non-Point Source Water Pollution
Non-point source is often difficult to identify because it is caused by a wide variety of distributed sources. Examples of non-point source pollution would be:

  • Runoff of heavy metals, chemicals, and other pollutants from mining operations
  • Runoff of soil, as well as other pollutants, from forestry operations
  • Runoff of oil, grease, and other such contaminants from roads and paved surfaces, like concrete and asphalt
  • Runoff of pollutants and even simple soil erosion from construction sites
  • Runoff from oil, gasoline, pet feces, litter, and even salt to melt the ice and snow in urban and suburban settings,
  • Runoff of pesticides and fertilizers from agriculture, such as farms and even just domestic lawns.

Copper Mine
Copper Mine
Agriculture Runoff
Agriculture Runoff
Road Construction
Road Construction


Ocean pollution is another large problem that is caused by both point and non-point sources.

The majority of pollution in oceanic and marine locations is the result of point sources of industrial wastewater, sewage, and offshore oil operations, while non-point sources are primarily agricultural runoff, air pollution, and maritime transportation.

Oil Rig

3. Historical Examples of Water Pollution

Let's discuss some real world examples of water pollution and its far reaching effects.

3a. Camelford
In 1988, in Camelford, Cornwall, England, 20 tons of aluminum sulfate were accidentally introduced to the public drinking water system, an amount which is 3,000 times higher than legally permitted. It is considered to be one of England's worst large scale poisonings and has had a multitude of short and long term effects on human health, such as memory loss and dementia. Victims of the incident who died many years later were discovered to have dangerously high levels of aluminum in their brains.

Map of Cornwall, England

3b. Jalisco
In 2014, in the Mexico state of Jalisco, 200 tons of fish were killed by high levels of sewage dumped into the lake. The sewage lowered oxygen levels and effectively suffocated the species of chub living in the lake. While the lake has been reopened for boating, it is still in an altered state with higher temperatures and algal blooms.

Lake in Jalisco, Mexico

3c. Gulf of Mexico
The Deepwater Horizon oil spill in the Gulf of Mexico is one of the most infamous water pollution catastrophes. The oil rig faulted and allowed 210 million gallons of oil to gush into the Gulf. It affected 8,322 different species, including aquatic life and birds. Many fish were found with increased levels of lesions. The number of dead baby dolphins washing up on shore increased as well and many other negative environmental impacts have been recorded and studied. 143 cases of human exposure and health impacts were also reported as a result of the spill.

Deepwater Horizon Oil Spill, Gulf of Mexico

3d. Chinese River Dolphin
The last example to discuss is the Chinese River Dolphin, which is believed to have gone extinct after an expedition in 2006 failed to find any. Its extinction is believed to have been caused by a variety of human causes, including pollution and overexploitation.

Chinese River Dolphin

Today we learned about water pollution and its negative impacts. We discussed the two categories of water pollution: point and non-point source. Within each type, we explored the different kinds of point and non-point source polluters. Finally, we discussed some historical examples of water pollution and its effects on humans and ecosystem health.