ROSARIO -- Grassland fires near a key South American river delta pose grave dangers to nearby wetland ecosystems and human health, according to environmental leaders, just a year after the water level of the once mighty Parana River dropped to a decades low.

The wildfires around the major riverside port of Rosario, crucial to transporting Argentina's massive grains harvest, have triggered alarm bells among ordinary residents as well as activists already concerned with prolonged drought worsened by this year's scarce rainfall and underscoring the consequences of a warmer, drier climate.

"The combined effect just makes it worse," said Enrique Viale, one of Argentina's leading environmental lawyers.

Smoke rises from the fire that continues to consume trees and pastures in a wetland near the city of Victoria, Entre Rios, Argentina August 18, 2022. Photo: Reuters

The Parana River, South America's second-longest waterway after the Amazon, saw its water level last year shrivel to its shallowest since 1944, according to official data, due to several drought cycles plus less rainfall in upstream Brazil. Its level remains very low.

A billowing haze caused by the wildfires, many set by farmers prepping the land for new crops, reached Buenos Aires, about 190 miles (300 km) south of Rosario, earlier in the week. The soot in the air provoked the ire of residents, with popular weather apps issuing forecasts that simply called for "smoke."

Earlier this month, thousands took to the streets of Rosario to protest the fires, demanding enforcement of laws that forbid them.

Fire burns in a wetland near the city of Victoria, Entre Rios, Argentina August 18, 2022. Photo: Reuters

"Plant life around the river delta is terribly damaged," said Roberto Rojas, the local director of emergency services.

He noted that some 28,000 hectares had already been torched prior the most recent fires, while total land lost to the flames has reached as high as 500,000 hectares in recent years.

"With the climate like it is, so much wind and no rain, we can only wait to see how this story ends," added Rojas.