River pollution is a major global environmental problem that has significant consequences for both human health and the natural world. Rivers are essential for life, providing vital resources such as freshwater for drinking, for irrigation, or hydropower for electricity; and are a home for a wide range of unique plant and animal species that are contributing to creating a healthy well-functioning ecosystems.
When rivers, as large bodies of fresh moving water, are polluted, these benefits are lost, and the negative impacts have adverse effects on both terrestrial and aquatic life. Severely polluted rivers can be found in many different countries. Water pollution is often the result of a variety of factors including especially the large scale industrialization, modern agriculture, energy production, and urbanization.
The question of how to compare levels of pollution is a tricky one. Although it’s easy to talk of sheer amounts of chemicals pumped into waterways, there are other factors to consider as well. These factors include, for example, number of people or species affected by water contamination, while it is also difficult to quantify precisely the effects of pollutants, and over what scale they happen. Regardless of definitions of the term ‘most polluted’, there’s no doubt that the rivers on the following list are in need of a serious clean-up.
Why do rivers get polluted?
There are many sources of river pollution worldwide, and the specific sources that are the biggest contributors to pollution can vary from one river to another. Some common sources of river and/or freshwater pollutants, that occur pretty much in every country at differing scale, include:
- Agricultural runoff: This occurs when chemicals used in agriculture, such as fertilizers, pesticides, herbicides or other synthetic substances, wash into rivers and streams from farmed lands with rain or irrigation water.
- Industrial discharges: Many industries release chemicals and other pollutants into rivers as part of their operations. This includes even power plants that burn fossil fuels and transport industry.
- Sewage: Both untreated and partially treated sewage is a major source of river pollution.
- Stormwater runoff: When it rains, water can wash pollutants from streets and other urban areas into rivers and streams.
- Leaking underground storage tanks: These can leak chemicals, such as gasoline and oil, into the ground, where they can then make their way into rivers and streams.
- Solid waste: Improperly disposed solid waste from households, or industries easily ends up floating in rivers. The problem usually arises from insufficient waste management within municipalities, illegal landfills or absent waste removal facilities in an area.
In general, we can say that the biggest sources of river pollution are likely to be those that are most common and widespread in a given region and the river catchment area.
So, naturally, a problem that is causing the most trouble in one area may not be the worst pollution contributor in another region. For example, in an area with heavy industrial agriculture, we may expect high levels of pesticide and fertilizer runoff, as opposed to industrial discharge.
What is the biggest source of river pollution worldwide?
It is estimated that globally 80 percent of domestic wastewater and raw sewage is dumped back into the water supply untreated.
Sewage water pollution is harmful because it contains a mixture of various contaminants that can be harmful to human health and the environment. Sewage can contain bacteria, viruses, parasites, and other microorganisms that can cause illness and disease, especially to children and elderly if ingested or if they come into contact with the skin.
It can also contain nutrients like nitrogen and phosphorus that can lead to the overgrowth of algae in bodies of water, disrupting the balance of the ecosystem.
In addition, sewage can contain chemicals and other toxic substances widely used in households, like bleach. In developed countries, pharmaceuticals and birth control pills are often flushed down the toilet and sink.
These substances can accumulate in water and significantly change its properties, creating a toxic cocktail for organisms dependent upon this water source.
What are the top 10 most polluted rivers in the world?
It is difficult to accurately rank the most polluted rivers in the world, as pollution levels can vary significantly over time, and are dependent upon a variety of factors. However, some of the rivers that are frequently cited as being among the most polluted include infamous river:
The River Ganges in India
The Ganges is one of the most sacred rivers in Hinduism and is also a major source of water for millions of people in the region. Widely considered one of the filthiest rivers, the Ganges in India is undeniably unpleasant, unhealthy and a disgrace to its revered stature.
Over 400 million people rely on it, using it for drinking water, agriculture and bathing, with millions more pilgrims also coming to bathe and worship . However, because of an ever expanding population, it is so full of toxins that levels are over 3,000 times what the World Health Organization considers safe.
In addition to the discharge of untreated sewage and industrial chemicals into the river, the Ganges is also used as a dumping ground for a wide range of solid waste, including plastic and medical waste.
Industries such as leather production pump chromium and other chemicals into the water but even more disturbing, particularly to Western eyes, is the wholesale dumping of human and animal corpses, including babies, some cremated, others merely abandoned and left to rot .
The Citarum River in Indonesia
One of the most polluted rivers in the world is the Citarum River in Indonesia. This river, which is the main source of water for millions of people in the country, is heavily contaminated with industrial, agricultural waste and biological waste from households. Some portions of the river are inundated by plastic items and other debris from human activities. According to statistics, up to 200,000 households along the river still spill their wastewater directly into the river.
Citarum River in Indonesia supplies 30 million people with water but to rely on it is to put your life at risk. The Citarum River is home to more than 2,000 factories, which discharge their waste directly into the river, and the agricultural practices of local farmers also contribute to the pollution. The result is a river that is severely polluted with a wide range of toxic chemicals, including heavy metals and pesticides.
More than 200 textile factories are found along its 190 miles (300 kilometers) but thanks to demand for growth and consumer goods, little regulation has been applied to industry, leading to the river becoming choked with lead, arsenic, and mercury, creating a deadly cocktail of contaminants .
Detritus floats along in a tide of waste, with plastic, packaging and other unsavoury items clogging up waterways and devastating ecosystems. Fishermen have given up catching fish, as they are all dead, instead turning to recycling plastic, but while this entrepreneurial spirit is admirable, the reason behind it is heartbreaking.
Things are about to change, as there is a strong initiative to revert the pollution problem. Many programs have been set in motion that are trying to improve the management of local resources, improve sanitation, waste management and address runoff escaping from livestock and crop farming.
The situation is complex and meanwhile the pollution of the Citarum River has had serious consequences for both human health and the environment, with many people in the region suffering from waterborne illnesses and the river’s ecosystems being severely damaged.
The Yellow River in China
The Yellow River, also known as the Huang He, is a major river in northern China that has a long history of pollution. China’s environmental problems are well known, but the state of the Yellow River stands as one of the most damning examples of human short-sightedness.
The Yellow River is an important water source for millions of people in China, but it has been heavily polluted over the years due to industrialization, agricultural runoff, and the dumping of domestic waste into the river. In the past, the river has been prone to serious water pollution incidents, and it has been declared “dead” on several occasions due to the high levels of pollution and the lack of oxygen in the water.
Economic expansion is again responsible for much of the problem. For example, the city of Shizuishan, one of the world’s most polluted cities, boasts a veritable forest of chemical and pharmaceutical factories, and which are responsible for the surreal and terrifying sight of blood red waste pumping into the water and turning it a hideous purple .
In recent years, the Chinese government has taken steps to address the pollution in the Yellow River, including increasing regulation of industrial discharges, promoting the use of environmentally-friendly farming practices, and improving the treatment of sewage. However, the river still faces significant pollution challenges, and it is important for the government and other stakeholders to continue working to address these issues.
The Yamuna River in Northern India
The Yamuna River, which is a major tributary of the Ganges River in northern India, is heavily polluted. In recent years, the quality of the water in the Yamuna River has become a major environmental and public health concern, as it is no longer safe for drinking, bathing, or even for agriculture.
The severity of pollution in the Yamuna River has caused the Times of India to call it ‘beyond redemption’, with the Central Water Commission stating boldly that the water is safe for neither drinking nor agriculture .
Biochemical Oxygen Demand (BOD) refers to the amount of oxygen required by living organisms to break down organic material, and once it reaches certain levels, it becomes a pollutant, giving rise to harmful bacteria . In the Yamuna, BOD levels can be as high as 50 times the permissible level, putting millions of lives at risk.
The Indian government and various NGOs have been working to address the pollution in the Yamuna River, but progress has been slow due to the complexity of the problem and the lack of sufficient resources.
The Mississippi River in the United States
The Mississippi River is the largest river system in the United States, and it is a vital resource for the people and the environment of the region. The Mississippi, one of the world’s mightiest rivers, is also one of its dirtiest .
Like many rivers around the world, the Mississippi River has been subject to pollution from a variety of sources. The most significant sources of pollution in the Mississippi River are agricultural runoff and untreated sewage. Agricultural runoff can contain fertilizers and other chemicals that can contaminate the water, while untreated sewage contains bacteria, viruses, and other harmful contaminants.
Vast stretches exceed recommended levels for mercury, PCBs, sediment, and other contaminants, making it hazardous to swim, fish or use its waters for drinking. Worse still is the vast dead zone in the Gulf of Mexico which has been created by the sheer volumes of fertilizer and raw sewage pollution which flow from the river and which stands as a desolate reminder of our actions .
Industrial discharges and the dumping of waste from urban areas are also sources of pollution in the Mississippi River. In recent years, there have been efforts to reduce the pollution in the Mississippi River, including the implementation of stricter regulations on discharges and the treatment of sewage. But these steps take long time to bear visible effects and the efforts need to be continuous.
The Sarno River in Italy
The Sarno River is a river in Italy that flows through the Campania region in the south of the country. It is a tributary of the Sele River, which is itself a tributary of the Tyrrhenian Sea. The Sarno River has a long history of pollution, and it is considered one of the most polluted rivers in Europe . Although its upper reaches are virtually pristine, travelling its length reveals waters covered with oily scum and chemical foam.
One of the main causes of pollution in the Sarno River is industrial discharges. The river flows through a region of Italy that is heavily industrialized, and many of the factories and other industrial facilities in the area release their waste into the river. The waste from these facilities contains a variety of contaminants, including chemicals and heavy metals.
Agricultural runoff is another major source of pollution in the Sarno River. The river flows through an area that is home to many farms, and the chemicals and fertilizers used on these farms leach into the river and contaminate the water.
Untreated sewage is also a significant contributor to the pollution in the Sarno River. Many of the communities along the river do not have adequate sewage treatment facilities, and their waste is often released directly into the river.
Mass dumping of untreated agricultural and industrial waste but research also points to illicit drugs such as cocaine and morphine in the water and which pose an entirely new, but as yet undetermined, threat to humans and wildlife .
The Marilao River in the Philippines
The Marilao River runs through the Philippines and suffers greatly from increased pollution loads, causing environmental degradation and numerous human health issues .
This contamination comes from a variety of sources, notably precious metal refining, lead acid battery recycling, jewelry making and open dumpsites.
Problems stem from the fact that the river is used for aquaculture, with the fish bioaccumulating the toxins and passing them up the food chain, with significant risks of heavy metal poisoning.
The Pasig River in the Philippines
The Philippines is also home to the Pasig River. The river is cutting through the heart of Manila and is subject to a variety of sources of pollution and problems connected with it. The contaminants range from untreated sewage, industrial waste, to household solid waste of biological and non-biological origin.
Problems started after WWII, when thousands flooded into Manila looking for work. Slums and industries sprang up, with untreated sewage released wholesale into the water, along with unregulated discharges from factories, tanneries, textile producing factories and chemical plants. The accumulation of toxin has led to the river being biologically dead.
The high levels of pollution in the Pasig River have led to environmental degradation and health problems for people living in the region. The river bed is filled with siltation and sediments from pollution sources and often floods low lying settlements, spreading contaminated water to unfortunate households. Efforts have been made in recent years to clean up the river and improve its water quality, but the task is ongoing and much more work needs to be done.
Why are rivers in the Philippines polluted so much that they make our list twice?
There are several reasons why rivers are contaminated with toxins and other dangerous pollutants in this country of islands. One major reason is the lack of proper sewage treatment facilities around the country. Many people in the Philippines do not have access to proper sanitation, and their sewage is often released directly into rivers and other bodies of water.
Industrial waste is also a major contributor to river pollution in the Philippines. Due to the lacking enforcement and regulations, many industries release their waste into rivers without proper treatment, contaminating the water with industrial by-products.
In addition, household garbage and solid waste can also end up in rivers. Poor solid waste management is a significant problem in the Philippines, with much of the garbage not being properly collected or disposed of.
The Tiete River in Brazil
The Tietê River is a major river in Brazil that flows through the state of São Paulo. It is the longest river in the state and is an important source of water for the region. The Tietê River has a long history of pollution dating back to the early 20th century. As the city of São Paulo grew and industrialized, the river became increasingly polluted due to raw sewage, industrial waste from the city, and domestic wastewater and solid waste released into its waters.
The high levels of pollution in the Tietê River led to environmental degradation and health problems for people living in the region.
In fact, the river received so much sewage and factory discharges that by the 1990s it was declared dead. Toxic foam formed on the surface during dry months, giving rise to massive public outcry to improve treatment infrastructure, but even so, several million citizens still lack basic sewage .
In the following years, there were several efforts to clean up the Tietê River, including the construction of sewage treatment plants and the implementation of stricter regulations on industrial waste.
The Yangtze River in China
The Yangtze River is the longest river in China and the third longest river in the world. The Yangtze River Basin is home to a large portion of China’s population and is an important economic and agricultural region. This important river supplies 40% of China’s freshwater and contributes 40% to the country’s GDP .
These facts make it even more alarming that it is so polluted to be on our list of the top 10 most polluted rivers in the world. Being so big and covering such a big part of the country already somehow predisposes the river to pick up pollutants along the way.
One major factor is the high levels of untreated sewage that are released into the river. The Yangtze River Basin is home to a large portion of China’s population, and the lack of proper sewage treatment facilities has led to untreated sewage being released into the river. Poor solid waste management is a significant problem in China, with much of the garbage not being properly collected or disposed of.
Almost half of the country’s waste ends up in its waters, amounting to 25 billion tons, causing fisheries to go extinct, severe health problems such as intestinal diseases and thousands of dead pigs to end up its tributaries .
The river flows through many heavily industrialized areas, and many industries release their waste into the river without proper treatment, contaminating the water with toxic chemicals. So is true even with the agricultural runoff and synthetic chemicals from agricultural lands ending up in the river.
How to clean polluted river water? Is there a solution to the problem?
As with any extensive pollution situation, it is not easy to fix the problem due to the complexities of the situation and diverse sources of contamination. Most rivers listed above are severely polluted due to numerous factors that mainly involve faulty management of industrial development of an area and a lack of infrastructure in places that have become heavily urbanized over the course of years. However, if we look at the water pollution problem from the general perspective, there are a few steps to follow.
One approach is to start by treating the sources of pollution at their point of origin. This means building sewage treatment plants to treat sewage before it is released into the river, implementing stricter regulations on industrial waste to prevent it from being released into the river, and switching to sustainable agricultural practices that reduce the runoff of synthetic chemicals and excess nutrients used in farming into the river.
Another approach is to use physical, chemical, and biological methods to remove pollutants from the river water. This involves the use of physical barriers to block and remove debris from the water, using chemicals to break down or neutralize pollutants, and using plants and bacteria to naturally break down pollutants.
Finally, it is also important to educate the public about the importance of protecting rivers and preventing pollution. This represents awareness campaigns, as well as effective implementing of water protection policies to encourage environmentally friendly behavior within a river catchment area.
The whole approach of addressing the pollution of a whole river ecosystem is a complex and ongoing process that requires the cooperation and joint efforts of government agencies, community organizations, and individual households.
It is worth noting that these are just a few examples, and there are many other rivers around the world that are also heavily polluted. In general, rivers that are heavily industrialized or located in areas with poor environmental regulations are more likely to be polluted. Pollution can have serious consequences for both human health and the environment, and it is important that efforts are made to address the problem and protect these vital resources.