A severe drought has dropped water levels on a major Amazon tributary to their lowest point since officials began keeping records more than a century ago, the government reported Monday, cutting off dozens of communities who depend on the river for work and transportation.
Floating homes along the Rio Negro now rest on muddy flats, and locals have had to modify boats to run in shallower waters in a region without roads. Some riverbanks have caved in, although no injuries have been reported. Enormous fields of trash and other debris have been revealed by the disappearing waters.
The drought is hurting fishing, cattle, agriculture and other businesses, prompting authorities to declare a state of emergency in nearly 40 municipalities. Amazonas state officials said more than 60,000 families have been affected by the drought.
The government has distributed about 600 tons of food, water and medicine, much of it by helicopter to isolated villages.
"It is a difficult situation for the community," resident Josimar Peixoto told Globo TV. "The families are struggling here."
The government's geological service said Monday that the Rio Negro was measured at a depth of 13.63 meters (44.72 feet) the previous day near the jungle city of Manaus, the lowest since a measuring system was implemented in 1902.
Manaus, in northern Brazil, is where the Rio Negro is at its deepest and where it merges with the Amazon River _ meaning some places upstream are nearly completely dry.
The previous low was 13.64 meters (44.75 feet), recorded in 1963.
An engineer and hydrology expert with the geological service said rains in remote parts of the Amazon will begin raising river levels, but it will take time for that water to reach Manaus.
"The water is expected to start rising again in about three to four weeks," Daniel Oliveira told The Associated Press.
In June 2009, the Rio Negro hit a record high of 29.71 meters (97.5 feet) near Manaus following months of heavy rains.
At that time, flooding across the Amazon basin left more than 400,000 homeless and killed more than 50 people. Those high waters caused the people now experiencing drought to build new, higher floors onto their stilt houses in an effort to escape the rising river.
Cycles of flooding and drought have been common in the world's largest remaining tropical wilderness, but they have been more extreme recently, shifting from record floods to record drought in relatively short periods of time, experts say. Many suspect global warming could be driving the whipsaw changes.
A report last year from Brazil's National Institute for Space Research, which tracks weather patterns, stated that its weather models forecast "rising global temperatures because of ongoing greenhouse gas emissions" and "project a decrease in rainfall across much of Brazil due to warmer waters in the Atlantic and Pacific oceans causing changes in wind patterns across South America."
The document says the changes could affect Brazil's energy sector: More than 70 percent of the nation's energy comes from hydroelectric sources, which would be hurt by reduced rainfall.
Associated Press writer Bradley Brooks contributed to this report from Rio de Janeiro.