MEXICO CITY, March 12 (UPI) -- The United Nations is expected issue a report this week that most of the 500 largest rivers in the world are drying up or polluted.
The World Water Development Report will condemn the trend as a "disaster in the making" and urge changes in how the waterways are utilized and cared for, the Independent reported.
The London newspaper says dams are preventing the water flow from the 20 longest rivers into the ocean and sea.
The water shortage, and at some points the rising temperature of the water attributed to global warming, is having a negative affect on fish species.
The Nile, Colorado, Jordan, Rio Grande, Pakistan's Indus and China's Yellow River are all much weaker as they flow into the ocean, if water reaches that far at all.
Industrial pollution is also harming the waterways and the remaining clean water of the world's rivers is being used by residential, industrial and agricultural expansion.
The report is to be officially unveiled Thursday during a conference in Mexico City.