While it is hard to rank rivers and lakes around the world in terms of who is THE worst, there are a few that stand out in the crowd. Pollutants like industrial waste, sewage runoff, overpopulation and agriculture discharges all make for quite a toxic brew. When you count in the fact that many of these major rivers and lakes supply food to nearby major population centers then they are having an even greater effect than as simply some polluted body of water in the middle of nowhere. Below are a few of the worst offenders that you should watch out for.
Lake Victoria borders three countries in East Africa - Kenya, Tanzania and Uganda - making it extra difficult to negotiate cleanup and pollution prevention. As there are few enforced regulations, residents wash cars in the same lake water that sewage water is regularly released in and that they also end up bathing in. Even worse, people who come in contact with the water are susceptible to coming away with several diseases including, schistosomiasis, bilharzia, cholera, pneumonia, diarrhea, and several skin diseases.
The 200-mile long Citarum River in Indonesia hosts more than 500 factories along its banks and is quite possibly the most polluted river in the world. There is so much garbage coating the surface that in many places you can't see the water, and it is more profitable to forage for garbage than making a living fishing the river, though you do risk catching a nasty disease by spending any time in it.
The Great Lakes (US/Canada) have taken a beating over the years thanks to pollution from the auto industry, oil refineries, steel plants, agricultural runoff and pollution, chemical plants and transportation runoff. While not the worst on this list, the lakes have accumulated a toxic soup that we have yet to deal with.
This 3,400 mile-long Yellow River in China is frequently contaminated by chemical spills, and frequent diversions and damming, which causes the Yellow to often run dry and sometimes even turn red. 1/3 of the river is unusable, but this doesn't seem to be slowing things down as the river is used to provide water for millions of people in China, whose expanding cities are another reason the river is contaminated.
While small compared to the others on this list (only 65 miles), the Riachuela River, running through the heart of Buenos Aires, is referred to as the largest open pit toilet in the world, absorbing over 325,000 tons of sewage each day. Lead, mercury, cadmium, nitrates and copper all pollute this river and affect drinking water supplies for the over 5 million people living in the area.
Lake Onondaga (US) is so polluted it was designated a hazardous waste site by the US Environmental Protection Agency. Phosphorous, ammonia, nitrite, mercury, bacterial contaminants, from a long history of industrial activity in the area, along with non-point source pollutants, combine to make this lake one toxic soup.
The Sarno River is regarded as the most polluted river in Italy and possibly all of Europe. Agricultural and sewage runoff frequently contaminates the river and treatment methods are inadequate to handle the pollution. The Sarno River frequently overflows its banks and therefore puts the local population at repeated risk for exposure.
Believe it or not, Lake Karachay (Russia) is completely contaminated with radioactive (and other types of) waste, that was dumped into the lake from the Mayak Nuclear Waste Storage Facility, starting in the 1950's. The waste is currently seeping out into area soils and rockbeds, threatening other rivers and even the Arctic. Scientists predict that if it makes it to the Arctic, it could spread around the world.
The Yumana River may be the site of historic and holy rituals, but it's also got its share of crap - literally. Over 3.5 billion litres of sewage pass through the river daily (making it over 100,000 times higher than limits safe for bathing), and the city removes another 1.1 billion litres of river water each day. No fish or plants can live in the river and holy leaders have threatened to boycott annual pilgrimages to the area due to the high contamination levels.
More than 2,800 factories line the shores of Lake Tai, the 3rd largest lake in China, contributing to its title as one of the largest and most polluted in the country. Officials have estimated a hefty $14.4 billion price tag to clean up all of the industrial dumping and sewage that contaminates these waters. Currently the waters have a green tint from all of the algae flourishing thanks to their ample source of industrial pollution in the lake.
The damage done to the Yangtze River due to pollution is so bad its been described as irreversible. Over 360 miles of the 3,860-mile long Yangtze River are polluted due to damming, inadequate sewage, industrial pollution and rapid population growth. Currently the river is responsible for 35% of the country's fresh water fish supply, while construction of the Three Gorges Dam along the river displaced over 1 million people.
The King River (Australia) is the most polluted river in all of Australia, principally due to mining activities along the river dating back to the 1880's. 1.5 million tons of mining tailings entered the river every year until 1995, while the fumes from the smelter created acid rain in the area. Today the mining operations continue to make the river highly toxic to marine life thanks to the leftover dissolved metals and tailings still in the river.
The Mississippi River (US). How could we forget this mammoth river that crosses 10 states and carries millions of metric tons of pollutants with it to its mouth in the Gulf of Mexico each year, creating a the notorious "deadzone." During the 1990s, this river discharged over 100 million pounds of toxics downriver each year. The Dead Zone is aptly named due to the low levels of oxygen, causing no aquatic life to survive in this area.