The Danube - stretching through 18 European countries, including ten EU member states - has been labelled as one of ten of the world's most threatened rivers which are fast dying as a result of dams, pollution and climate change.
More than 80 percent of the original floodplain area along the Danube and its main tributaries have been lost since the beginning of the 19th century, according to the report published by the World Wildlife Fund.
Adding to these alarming findings, further human activities, such as inappropriate river management and new constructions, continue to aggravate the problem.
According to the WWF, infrastructures planned as part of the EU Trans-European Network for Transport put at risk the most valuable natural stretches of the Danube, such as the Bavarian stretch in Germany, the Wachau valley in Austria and the middle and lower Danube in Hungary, Serbia, Romania and Bulgaria.
"Further canalising the river results not only in loss of biodiversity and wetlands - thereby increasing problems with flood management - but can also draw down water tables, risking access to drinking water for 20 million people in the region," the WWF said on Tuesday (20 March).
The Danube has repeatedly been hit by disastrous spring floods. The last time, in 2006, record high levels caused significant damage in Hungary, Serbia, Romania and Bulgaria.
Due to a repeated scenario, in 2004, all countries in the Danube river basin stepped up their cooperation and adopted an action programme aimed at better flood protection. This has led to mapping high risk areas, giving rivers more space by creating new water retention zones and ending new building in natural floodplain areas.
However, it is still expected that over 85 percent of the Danube could fail to meet the objectives of the EU Water Framework Directive, which aims to achieve the level of "good status" for all European waters by 2015.
"The freshwater crisis...mirrors the extent to which unabated development is jeopardising nature's ability to meet our growing demands," a freshwater policy officer at the WWF Sergey Moroz said.
"We must change our mindset now or pay the price in the not so distant future," he said, while calling on EU states to speed up the implementation of "the ground breaking EU law."
The directive foresees a situation where we are less wasteful of our water, the water we use is priced fairly, those who pollute it are made to pay and waste is properly treated rather than washed straight into waterways.
The Danube is the only European river listed among the world's ten most endangered. Five of them are in Asia alone - the Yangtze, Mekong, Salween, Ganges and Indus. The list also includes Latin America's La Plata and Rio Grande, the Nile in Africa and Australia's Murray-Darling.