http://www.waterconserve.info/articles/reader.asp?linkid=53729

Death of the world's rivers

This week an influential UN report will officially warn the world's governments of an "alarming deterioration" in the planet's rivers, lakes and other freshwater systems. Klaus Toepfer, the executive director of the United Nations Environment Programme, told the IoS yesterday that the state of the world's rivers is "a disaster in the making".
The UN's triennial World Water Development Report, compiled for an international conference in Mexico City which opens on Thursday, warns that "we have hugely changed the natural order of rivers worldwide", mainly through giant dams and global warming. Some 45,000 big dams now block the world's rivers, trapping 15 per cent of all the water that used to flow from the land to the sea. Reservoirs now cover almost 1 per cent of land surface.

Global warming is endangering even the rivers that have largely escaped damming.

The relatively untamed Amazon was hit by its most serious drought on record last autumn. And salmon are dying in Alaska's Yukon River - the world's longest undammed watercourse - because its waters are getting too hot.