WWF Names World's Top 10 Rivers at Greatest Risk

GLAND, Switzerland, March 21, 2007 (ENS) – Ten of world's largest rivers are drying up due to "the wanton waste of freshwater resources, poor governance, and a disregard for the needs of local people that frequently exacerbates poverty," finds a new report by the global conservation organization WWF.

The report, "World's Top Rivers at Risk," released ahead of World Water Day on March 22, lists the top 10 rivers that are dying as a result of climate change, pollution and dams.

Five of the 10 rivers listed in the report are in Asia. They are the Yangtze, Mekong, Salween, Ganges and Indus.

Europe’s Danube, the Americas’ La Plata and Rio Grande-Rio Bravo, Africa’s Nile-Lake Victoria and Australia’s Murray-Darling also make the list.

Rio Grande

The Rio Grande as seen from Matamoros, Tamaulipas, Mexico. Texas is visible in background. (Photo courtesy Wikipedia)
"All the rivers in the report symbolize the current freshwater crisis, which we have been signalling for years," says WWF Global Freshwater Programme Director Jamie Pittock.

"Poor planning and inadequate protection of natural areas mean we can no longer assume that water will flow forever," Pittock said. "Like the climate change crisis, which now has the attention of business and government, we want leaders to take notice of the emergency facing freshwater now not later."

The report summarizes the findings of eight wide-ranging and authoritative global assessments and identifies the threats mentioned with the greatest frequency - water infrastructure such as dams, over-extraction of water, climate change,invasive species, over-fishing, and pollution.

The 10 rivers highlighted are either those that already suffer most under the weight of these threats or are bracing for the heaviest impacts.

There are some rivers on the list that are so damaged that without serious restoration efforts they could be lost, and others that are relatively intact, but face massive degradation unless action is taken now to conserve them.

Yangtze: Pollution. The Yangtze River rises in the mountains of Qinghai Province on the Tibetan plateau, and fl ows 6,300 kilometers to the East China Sea, opening at Shanghai. Its catchment covers one-fifth of the land area in China.


The city of Chongqing on the Yangtze River. The whole of the lower section will be flooded by the Three Gorges reservoir. (Photo courtesy Three Gorges Probe)
The Yangtze river basin accounts for 40 percent of China’s freshwater resources, more than 70 percent of the country’s rice production, 50 percent of its grain, more than 70 percent of fishery production, and 40 percent of the China’s GDP.

The river is inhabited by 350 fish species, including the giant Yangtze sturgeon, of which 112 are found nowhere else. This basin is the sole habitat of the critically endangered Chinese Paddlefish, the endangered Finless Porpoise, and the now believed to be extinct Chinese River Dolphin, the most critically endangered cetacean in the world. The most threatened crocodilian species in the world, the Chinese Alligator, is only found in the lower reaches of the Yangtze.

This basin is inhabited by the giant panda, the largest salamander in the world, Audrias davidianus, the critically endangered Siberian crane, and the once-extirpated Pere David’s deer now re-introduced from captive stock.

Over the last 50 years, there has been a 73 percent increase in pollution levels from hundreds of cities, in the main stem of the Yangtze River, WWF reports. The annual discharge of sewage and industrial waste in the river has reached about 25 billion tons, which is 42 percent of the country’s total sewage discharge, and 45 percent of its total industrial discharge.

The major pollutants in the Yangtze mainstem are suspended substances, oxidizing organic and inorganic compounds, and ammonia nitrogen. This has reduced drinking water quality and contributed to eutrophication, the process by which the excess nutrients stimulate excessive plant growth and decay.

After 13 years of construction, the Three Gorges Dam is now built and will be fully operational in 2008. The Three Gorges Dam exacerbates water pollution by impounding waters, trapping sediment and increasing eutrophication.

Efforts to reduce pollution in the Yangtze River have been slow but promising, WWF says. Community pressure has successfully increased local enforcement activities such as fi eld inspections and increased pollution fees.

Mekong-Lancang: Over-fishing. The Mekong river basin is the largest in Southeast Asia. Rising in the mountains of China’s Qinghai province near Tibet, it flows south. It forms the border between Laos and Myanmar, most of the border between Laos and Thailand, and moves across Cambodia and southern Vietnam into the South China Sea.


The Mekong River widens out into the delta once it crosses the border into southern Vietnam. (Photo by Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC)
Unlike many major rivers in Asia, this river and its flood regime are relatively intact, and the lower Mekong basin is the most productive river fishery in the world.

The basin is home to at least 1,200 fish species, the highest fish diversity in any basin after the Amazon and Congo. Sixty-two fish species are found nowhere else in the world. This river harbors more species of giant fish than any other as well as the largest freshwater fish known to science, the Mekong giant catfish. The basin is inhabited by the Irrawaddy Dolphin, the Mekong population of which is critically endangered.

The Mekong River fishery is based on the annual wet season flood of its extensive floodplain, particularly the back flow of the river into the Tonle Sap Lake in Cambodia.

The scale of this beneficial flooding is threatened by the present and potential impoundment of floodwaters behind 58 existing and 149 proposed large dams, and by roads in the floodplains.

Despite the productivity of the Mekong, WWF reports, the threat of over-fishing is high because of the huge scale of subsistence fishing, the majority of which goes unrecorded, as well as poor fishing practices.

People illegally use small-meshed mosquito nets, which catch juveniles as well as adult fish, electro-shock fish with car batteries, and increasingly over-harvest fish with poison, WWF reports.

Salween, Nujiang or Nu River: Infrastructure, dams. The Salween flows from the Tibetan Plateau adjacent to the Mekong and the Yangtze rivers, in the "Three Parallel Rivers” World Heritage area, at the epicentre of biodiversity in China.

Dam construction poses the single greatest threat to the Salween River. China plans up to 13 large hydropower projects in a cascade that would transform the free-flowing river in upper basin into a series of channels and reservoirs.

Shared by China, Thailand, and Myanmar, formerly Burma, six million people live in the Salween watershed. They share the watershed with 92 amphibian species, and 143 fish species of which 47 are found nowhere else in the world, and the world’s greatest diversity of turtles.

The Salween delta and associated wetlands support populations of the unique fishing cat, the Asian small-clawed otter and the Siamese crocodile. The golden eye monkey, small panda, wild donkey of Dulong and wild ox still flourish in this basin.

Ganges: Water Over-extraction. The Ganges river basin runs from the central Himalayas to the Bay of Bengal, and covers parts of Nepal, India, China and Bangladesh.

The Ganges basin occupies 30 percent of the land area of India and is heavily populated, increasing in population density downstream to Bangladesh, the most densely populated country in the world. Approximately one in 12 people in the world live in the Ganges catchment area.


Worshippers take a dip in the Ganges River on a holy day that takes place once every 12 years. (Photo courtesy Kriyayoga Research Institute)
There are over 140 fish species in the Ganges basin, 90 amphibian species, and five areas supporting birds found nowhere else in the world. The basin is inhabited by five species of freshwater cetaceans including the endangered Ganges River Dolphin and the rare freshwater shark, Glyphis gangeticus.

Unique Sundarbans delta mangroves are found where the Brahmaputra River and Meghna River converge in the Bengal basin and support an enormous number of species, including the world’s last population of the mangrove-inhabiting tigers.

Water withdrawal poses a serious threat to the Ganges. In India, barrages control all of the tributaries to the Ganges and divert roughly 60 percent of river flow to irrigation.

The world's fifth largest dam, the Tehri Dam, completed in 2005, is part of the "garland of rivers" project in which the Indian government plans to link 37 major rivers, including all the major rivers flowing from the Himalayas, through a series of dams and canals to provide drinking water and generate electricity. In this US$125 billion "interlinking of rivers" scheme, India proposes to divert vast quantities of water from the Ganges to support drought-prone states in the south and east. This would further aggravate water poverty in Bangladesh.

Indus: Climate Change. The Indus river basin spans parts of four countries - Afghanistan, Pakistan, India and China - in an area that is more than 30 percent arid, much drier than the nearby Ganges river basin.

The Indus faces threat from climate change because of its high dependency on glacier water. The Himalayan glaciers provide the Indus with 70 to 80 percent of its water, the highest proportion of any river in Asia.

Even without warmer temperatures threatening to melt Himalayan glaciers, the Indus River faces scarcity due to over-extraction of water for agriculture. Fish populations, the main source of protein and overall life support systems for many communities, are also being threatened.

The Indus is inhabited by 25 amphibian species and 147 fish species of which 22 are found nowhere else in the world. It harbors the endangered Indus River dolphin, one of the world’s rarest mammals.

One of the many dams on the Danube River. (Photo by Anton Vorauer © WWF-Canon)
Danube: Infrastructure - Navigation. The most multinational river basin in the world, the Danube basin is roughly twice the size of California and its basin covers part or all of 19 riparian countries: Albania, Austria, Bosnia and Herzegovina, Bulgaria, Croatia, Czech Republic, Germany, Hungary, Italy, Macedonia, Moldova, Poland, Romania, Serbia, Montenegro, Slovakia, Slovenia, Switzerland and Ukraine.

Drastic changes to the Danube’s natural flow and surrounding lands to control floods, generate power, facilitate agriculture and waterway transport have already destroyed over 80 percent of the watershed’s valuable wetlands, floodplains and forests. What remains of the basin’s integrity is under intense threat from shipping infrastructure developments.

The Danube-Oder-Elbe-Canal Plan is proposed to enable ship passage from the Baltic to the North Sea, then southward to the Black Sea. This will indirectly or directly affect 46,000 hectares of 38 protected areas containing two national parks, six Ramsar wetland sites, and two biosphere reserves in five countries.

La Plata: Infrastructure - Dams and Navigation. The La Plata basin is the second largest river basin in South America, crossing five countries: Paraguay, Brazil, Argentina, Uruguay, and Bolivia. It has main tributaries, the Paraná, the Paraguay and the Uruguay Rivers.

The Paraná tributary river basin supplies Brazil's largest city Sao Paolo and its capital Brasilia, as well as 17 other cities of more than 100,000 people.

La Plata’s Pantanal wetlands, located mostly in southwest Brazil but also extending to southeast Bolivia and northern Paraguay, are the largest freshwater wetlands in the world, inhabited by a vast array of wildlife.


Scientist Pablo Bordino with a La Plata River dolphin (Photo courtesy Pablo Bordino)
The elusive Plata River dolphin, Pontoporia blainvillei, lives off the coasts of Brazil, Uruguay, and Argentina.

The basin faces the second greatest number of planned dams in the world: 27 large dams, of which six currently are under construction.

New impoundments and water diversions threaten the Paraguay River’s relatively pristine headwaters, which comprise the central artery of the Pantanal wetlands, and Uruguay River.

WWF says the Brazilian, Bolivian and Paraguayan governments’ plan for the massive navigation and hydroelectric dam project, "hidrovia," is proceeding without an adequate Environment Impact Assessment. The hidrovia would dredge and redirect the Paraguay and Paraná Rivers to create a 3,442 kilomteter long navigation channel at least three meters (10 feet) deep between Caceres, Brazil and the harbor of Nueva Palmira in Uruguay. This would provide cargo ships with access to the interior of Argentina, Bolivia, Brazil, Paraguay and Uruguay during the dry season.

Rio Grande - Rio Bravo: Water Over-extraction. The second longest river in the United States, the Rio Grande flows from the San Juan Mountains of Colorado, south through New Mexico. It forms the border between the United States and Mexico for two thirds of its course, opening into a small sandy delta at the Gulf of Mexico.

The Rio Grande basin is a globally important region for freshwater biodiversity with 121 fish species, 69 of which are found nowhere else. There are three areas supporting endemic bird species as well as a high level of mollusk diversity.

A high level of water extraction for agriculture and increasing domestic use threatens the Rio Grande. Most of the major tributaries and many of the lesser ones support substantial agricultural production. Irrigation accounts for more than 80 percent of all water taken from the river, but municipal needs are competing more and more as urban areas grow.

Currently, there are six very large dams and 100 large dams, eight of which are on the main stem of the river.

The area is experiencing persistent drought and the basin is facing per capita water scarcity. By 2025, it is expected to dry up still further.

Nile-Lake Victoria: Climate Change. The Nile River-Lake Victoria basin falls within 10 countries - Sudan, Ethiopia, Egypt, Uganda, Tanzania, Kenya, Rwanda, Burundi, Democratic Republic of Congo, and Eritrea - and is roughly the size of India. Originating at Lake Victoria, the Nile is the longest river on Earth, and meanders through a watershed that is more than 30 percent arid.

The Nile delta is home to virtually all of Egypt’s 78 million people, and the Nile basin supports 25 cities with more than 100,000 people.

The Nile river basin is home to 137 amphibian species, 69 wetlands that are important bird areas, and five areas supporting birds found nowhere else in the world. The Nile delta is one of the world’s most important bird migration routes and is a breeding ground for two endangered marine turtles, the loggerhead and the green turtle.

Lake Victoria sustains 343 fish species,including 309 endemic fish species, which makes it the highest globally in both categories.

Due to heavy human extraction and high evaporation, the Nile river basin and its inhabitants are especially sensitive to climate change. Current water withdrawal for irrigation is so high, that despite its size, in dry periods the river does not reach the sea.

Murray-Darling: Invasive Species. The Murray and Darling Rivers cross four Australian states and one territory, draining roughly 14 percent of Australia’s land mass.


The Murray-Darling River is large in terms of its length and catchment area, but small and erratic in terms of discharge, and surface runoff. (Photo courtesy River Murray Urban Users LAP Committee)
The Murray-Darling river basin is a vital source of water for the major cities of Adelaide and Canberra, but it is more than 30 percent arid.

Emus, koala bears, Western grey kangaroos, bearded dragon lizards, red-rumped parrots, black swans, pelicans, and dolphins are among the species that live in the Murray-Darling basin.

There are around 30,000 wetlands, 12 of which are internationally recognized Ramsar sites. The basin is known for its diversity of crayfish and freshwater snails and is inhabited by 16 mammal and 35 bird species that are nationally endangered the WWF report states.

Nine of the 35 native fish species are nationally threatened, two are critically endangered, and 16 are threatened under state jurisdictions.

By contrast, both the invasive European Carp and Plague Minnow are now abundant. This is likely a result of significant changes in water flow, thermal pollution, instream habitat degradation, and barriers to fish passage which have fostered conditions favorable to invasive species over native fish populations, says the report.

Aquarium fish and plants released into the Murray-Darling and crowding native species out. Compounding the damage are riparian trees introduced for aesthetic purposes, and a variety of plants introduced for agricultural and ornamental purposes that are invading floodplains and other wetlands.

The WWF report calls on governments to better protect river flows and water allocations in order to safeguard habitats and people’s livelihoods.

"Conservation of rivers and wetlands must be seen as part and parcel of national security, health and economic success,” says Pittock. "Emphasis must be given to exploring ways of using water for crops and products that do not use more water than necessary.”

In addition, WWF urges, cooperative agreements for managing shared resources, such as the UN Watercourses Convention, must be ratified and given the resources to make them work.

To access the report, "World's Top Rivers at Risk," click here.