BRASILIA, Brazil — The Amazon holds one-fifth of the world’s fresh water and is beginning the dry season with many of its rivers already at critically low levels, prompting governments to anticipate contingency measures to address issues ranging from disrupted navigation to increasing forest fires.

“The Amazon Basin is facing one of the most severe droughts in recent years in 2024, with significant impacts on several member countries,” stated a technical note issued last week by the Amazon Cooperation Treaty Organization, made up of Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, Suriname and Venezuela.

In several rivers in the southwestern Amazon, water levels are the lowest on record for this time of year. Historically, the driest months are August and September, when fire and deforestation peak. So far, ACTO says the most affected countries are Bolivia, Peru and Brazil.

On July 29, Brazil’s federal water agency decreed a water shortage in two major basins, Madeira and Purus, which cover an area nearly the size of Mexico. The next day, Acre state declared an emergency amid an impending water shortage in its main city. In June, neighboring Amazonas state adopted the same measure in 20 of its 62 municipalities that are mostly only accessed by water or air.

These steps were taken more than two months earlier than in 2023, when most of the Amazon basin suffered its worst drought on record, killing dozens of river dolphins, choking cities with smoke for months and isolating thousands of people who depended on water transportation. The measures are used to increase monitoring, mobilize resources and personnel, and request federal aid.

The depth of Madeira River, one of the largest Amazon tributaries and an important waterway for soybeans and fuel, went below 10 feet near Porto Velho on July 20. In 2023, that occurred Aug. 15. Navigation has been limited during nighttime, and two of Brazil’s largest hydroelectric plants may halt production, as happened last year.

In the Amazonas town of Envira, nearby rivers have become too shallow to navigate. Local officials have asked elders and pregnant women to move from riverine communities to the city center because otherwise medical help may not be able to reach them. Farmers who produce cassava flour can’t get it to market. As a result, this Amazon food staple has more than doubled in price, according to the local administration.

Another concern is fire. There were around 25,000 fires from January until late July — the highest number for this period in almost two decades. In the Amazon, fires are mostly human-made and used to manage pastures and clear deforested areas.

“It’s been two years in a row of extreme events,” said Julie Messias, Acre’s secretary of environment. “The result is that we are facing a threat of food shortage. First the crops were flooded, and now the planting period is very dry.”