Brazilians cross the muddy bottom of the Rio Negro, a major tributary to the Amazon river, in the city of Manaus, Oct 26, 2010. A severe drought has pushed river levels in Brazil's Amazon region to record lows, leaving isolated communities dependent on emergency aid and thousands of boats stranded on parched riverbeds. [Photo/Agencies]

Brazilians cross the muddy bottom of the Rio Negro, a major tributary to the Amazon river, in the city of Manaus, October 26, 2010.