Wildlife Dying En Masse as South American River Runs Dry

The Pilcomayo River in Paraguay is littered with dead caiman and fish carcasses as the government scrambles to find a solution.

Vultures rest in the tree’s upper branches, their black bodies in stark contrast to the blanched wood beneath their feet. Below them, caimans and capybaras crawl in sucking mud through the Agropil lagoon, seeking water that is unlikely to arrive for many months. The river has dried up, and there is nowhere for them to go.

The lagoon, located in the western Paraguayan province of Boquerón, is just one of many stretches of the Pilcomayo River suffering an extensive die-off of caiman, fish, and other river creatures. There have not been any official estimates from the Ministry of the Environment, but Roque González Vera, a journalist for ABC Color in Paraguay, reports utter devastation in some places: Up to 98 percent of caimans (Caiman yacare) are suspected dead, and 80 percent of the capybara (Hydrochoerus hydrochaeris) population has died.

Paraguay is in the midst of an ecological crisis.

Caimans (Caiman yacare) and capybaras (Hydrochoerus hydrochaeris) are stuck in the mud of the dry Pilcomayo River, which forms the border between Paraguay and Argentina. [PHOTOGRAPH BY JORGE ADORNO, REUTERS]         

The crisis stems from a combination of drought and mismanagement that has left the Pilcomayo River dry for nearly 435 miles (700 kilometers), according to Vera. On June 24, Paraguay declared an environmental emergency, but little has been done, or can be done, to provide relief for the imperiled animals until the wet season returns. The dry season typically lasts through October, and the annual recharge does not generally occur until January.

So, what went wrong?

A Perfect Storm of Drought and Mismanagement

The Pilcomayo River originates in the Bolivian Highlands, which form the upper basin of the river. The lower reaches run through the Gran Chaco—a hot, semiarid lowland also known as the Chaco Plain—and form a 518-mile (834-kilometer) international border between Argentina and Paraguay. This stretch of the river relies on an annual, three-month pulse of water from the upper basin during its rainy season (roughly January to March). Quite simply, this past year did not deliver. 

According to the Ministry of Public Works and Communication (MOPC), the drought is the second worst in the past 30 years, and the paucity of rain has not been seen since 1996-97.

Alone, the drought posed a threat to wildlife and agriculture, but the crisis has been exacerbated by the mismanagement of water resources and infrastructure by the Paraguayan government, according to Vera.

In a recent article, the reporter argues that the government is complicit in the wildlife die-off, alleging laziness, inefficiency, and irresponsibility in the rehabilitation of the Paraguayan channel.

To some extent, the government agrees. The MOPC concluded that the National Commission of the Pilcomayo did an insufficient job of maintaining the river’s channels and canals and recently fired the head of the commission, Daniel Garay. Garay was also charged for the alleged irregularities.

"In some places, up to 98 percent of caimans are suspected dead, and 80 percent of the capybara population has died.
However, the mismanagement also extends across the border to Paraguay’s neighbor, Argentina".

In 1991, the two countries signed a water distribution agreement for the Pilcomayo, but they have struggled to maintain a fair distribution of water. In any given year, the river largely flows in one country and not the other. A recent review of the river proposed that the country that gets the water is either lucky the river shifted to them, and/or they were more diligent in canal work.

Both countries have built up artificial canals outside the agreement—ample mistrust between the nations fuels the construction—but Argentina appears to have done a better job managing theirs, while also adding some reservoirs to hold water surpluses. In recent years, they were luckier and more diligent: Argentina has the water now.

How long Argentina keeps the water is largely dependent on a third factor: the natural characteristics of the Pilcomayo River.

Natural Phenomenon?

Oscar Orfeo, an Argentinean geologist at the Center for Applied Coastal Ecology, believes the lack of water is simply a natural result of the river’s morphology; the river simply does what it wants. The artificial canals cannot control the slope of the plain or the river’s shaping capacity, he says.

Orfeo also believes that the current environmental emergency cannot be attributed to a period of extreme drought but is really due to the “wandering” behavior of the river.

This wandering is largely related to the significant amounts of sediment the Pilcomayo transports downstream—some 140 million tons of sediment every year, one of the highest amounts in the world. The sediment, in combination with wood debris carried downstream, has created a blockage that disperses the river outside the channel into the surrounding land.

As the blockage moves farther upstream every year, the dry river channel grows. It has now been nearly a hundred years since the Pilcomayo’s main channel connected with the Paraguay River in Asunción.

Caimans have been hit particularly hard as the Pilcomayo River disappears. In some places along the river, they have lost 98 percent of their population. [PHOTOGRAPH BY JORGE ADORNO, REUTERS]

With both human and natural forces at play, scientists in Paraguay worry the current crisis could easily become an annual occurrence.

Seeking a Solution

In the face of public pressure, the Minister of Public Works and Communication, Ramón Jiménez Gaona, announced that the government is working with local authorities, indigenous groups, and residents to remedy the situation.

Yet, despite the claims of the government, so far there has been little action to address the situation, says Vera.

At the time of this publishing, National Geographic had not received a response from the Ministry of the Environment or the National Commission of the Pilcomayo, which is housed in the MOPC.

In reality, it is hard to see a clear solution right now; there is no water to release or divert. Existing options to rehabilitate the Pilcomayo mostly center on cleaning and updating the canals that are filled with sediment, but it is neither quick nor easy to do so. To restore a consistent flow on both sides of the border, Paraguay and Argentina must commit to sharing water, but cooperation has been hard to come by.

Until the infrastructure is developed and maintained, observers can only watch and wait, hoping that it rains enough next year to save the animals, or that the river shifts back into its Paraguayan channel.

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