World Water Day 2021: Most polluted waterways worldwide

About 4 billion people experience severe water shortages for at least one month a year and around 1.6 billion people - almost a quarter of the world's population - have problems accessing a clean, safe water supply, according to the United Nations.

While the UN's Sustainable Development Goals call for water and sanitation for all by 2030, the world body says water scarcity is increasing and more than half the world's population will be living in water-stressed regions by 2050.

On UN's World Water Day, let take a look at the most polluted waterways around the world.

An aerial view shows workers collecting plastic trash that litters the polluted Potpecko Lake near a dam's hydroelectric plant near the town of Priboj, Serbia.

The river Lim which fills the lake is swollen by melting snows, and according to activists, it has carried in more than 20,000 cubic meters of plastics from unregulated dumps along its banks in Serbia, Montenegro and Bosnia.

As the garbage also threatened the functioning of a hydroelectric plant, authorities in Belgrade ordered an immediate clean-up. The operators collect up to 100 cubic meters of plastic and other trash daily and take it to a landfill about 80 km (50 miles) away. 

An aerial view shows hoverboats on the ice of lake Baikal near the village of Bolshoye Goloustnoye in Irkutsk region, Russia.

Lake Baikal remains one of the world's cleanest fresh water reservoirs. But pollution and the growth of weeds are harming microorganisms, sponges and some molluscs that filter its waters.

The Baikal pulp and paper mill and its sewage treatment facilities were closed seven years ago, but pollution has spread significantly since then, according to local media. That, some experts say, is because pollution left behind at the industrial site is draining into the lake. 

An aerial view shows domestic waste floating on the stream of the Citarum river in Bandung, Indonesia.

The government has pledged to clean the Citarum river, considered among the world's most polluted, and make the water there drinkable by 2025, but household and industrial waste have continued to flow in its stream. 

An aerial view shows people fishing from a wooden bridge at the Pisang Batu river, which flows through a densely populated area and is polluted by domestic waste, in Bekasi, on the outskirts of Jakarta, Indonesia.

Pisang Batu river, on the outskirts of Jakarta, made national headlines in 2019 after plastic garbage and organic waste from nearby households completely covered its surface stretching 1.5 kilometres. The river has fewer waste after several cleanup operations, but the water is black, emitting a strong odour. 

An aerial view shows water contaminated with raw sewage flowing via open channels into the ocean at Hann Bay on the eastern edge of Dakar's peninsula, whose sandy shorefront is discoloured by stagnant algae, in Dakar, Senegal.

Inadequate sewer infrastructure in the adjacent neighbourhoods of Hann-Bel-air and Mbao means large amounts of solid and liquid waste is released into the bay untreated year-round.

On Hann beach, an artisanal fishing hub, old tyres lie around a canal filed with putrid water and trash. "We live in sickness here, because our families are in direct contact with this water and this waste," said fisherman and local resident Pape Malick Ba.

Last September, the water and sanitation ministry launched a long-promised project to clean up Hann bay at a cost of 93 billion CFA francs ($168 million). As residents wait for it to yield results, they struggle to keep their beaches clean through citizen initiatives. 

An aerial view shows rotten trees in a toxic lake near southwestern town of Yatagan in Mugla province, Turkey.

The toxic lake, known as an ash dam, is created by a mix of waste water and polluted ash which are both produced at the nearby Yatagan power station, according to environmental activist Deniz Gumusel.

The lake contains heavy metals such as selenium, cadmium, boron, nickel, copper and zinc that are leaking into the earth and groundwater of the Yatagan Plain, an agricultural plain that feeds both Yatagan and Mugla towns.

It is one of 15 ash dams in Turkey, which environmental organizations are trying to tackle, to stop them from causing further damage to nature.