KOLONTAR, Hungary — Red sludge flowed into the Danube River on Thursday, threatening a half-dozen nations along one of Europe's key waterways. Monitors took samples every few hour to measure damage from the toxic spill and emergency officials declared one Hungarian tributary dead.
As cleanup crews gathered deer carcasses and other wildlife from the villages in southwestern Hungary flooded by the industrial waste, environmental groups warned of long-term damage to the farming region's topsoil.
Conflicting information swirled about the dangers posed by the ankle-deep muck coating the most seriously hit areas after the collapse of a waste-storage reservoir at a nearby alumina plant Monday.
The Hungarian Academy of Sciences maintained that while the material was a continued hazard, its heavy metal concentrations were not considered dangerous to the environment.
"The academy can say whatever it wants," fumed Barbara Szalai Szita, who lives in Devecser, one of the hardest-hit villages. "All I know is that if I spend 30 minutes outside I get a foul taste in my mouth and my tongue feels strange."
Hungary's environment minister, Zoltan Illes, said the henna-colored sludge covering a 16-square-mile swathe of countryside does have "a high content of heavy metals," some of which can cause cancer. He warned of possible environmental hazards, particularly if it were to enter the groundwater system.
With rain giving way to dry, warmer weather over the past two days, the caustic mud is increasingly turning to airborne dust, which can cause respiratory problems, Illes added.
"If that would dry out then ... wind can blow ... that heavy metal contamination through the respiratory system," he said.
Amid the conflicting reports, officials had one piece of encouraging news: The mighty Danube was apparently absorbing the slurry with little immediate harm beyond sporadic sightings of dead fish.
The red sludge, a waste product of aluminum production, reached the western branch of the Danube early Thursday and was flowing into its broad main stretch by noon. By evening, it was moving southward toward Serbia and Romania.
At monitoring stations in Croatia, Serbia and Romania, officials were taking river samples every few hours, though experts hoped the river's huge water volume would blunt the impact of the spill.
Hungarian rescue agency spokesman Tibor Dobson said the pH content of the sludge entering the Danube had been reduced to the point where it was unlikely to cause further environmental damage. The waste, which had tested at a highly alkaline pH level of 13 soon after the spill – similar to lye or bleach – was under 10 by Thursday.
A neutral pH level for water is 7, with normal readings ranging from 6.5 to 8.5. Each pH number is 10 times the previous level, so a pH of 13 is 1,000 times more alkaline than a pH of 10.
The tributaries feeding the Danube from the area around the spill were not so fortunate. The Marcal River, stained ochre and devoid of fish and other aquatic life, was declared a dead zone.
"Life in the Marcal River has been extinguished," Dobson said of the waterway, which is fed by streams around the accident site and carried the waste into the Raba River, which then flows into the Danube.
He said emergency crews were pouring plaster and acetic acid – vinegar – into the area where the Raba and Danube meet to lower the sludge's pH value.
"The main effort is now being concentrated on the Raba and the Danube," he said. "That's what has to be saved."
An AP television crew watching cleanup efforts at the confluence of the Raba and the Danube said neither river showed visible signs of pollution.
An environmental group that monitors threats to the Danube said the breached reservoir was on a 2006 watch list of some 100 industrial sites that were at risk for accidents that could contaminate the 1,775-mile-long river. The International Commission for the Protection of the Danube River coordinates conservation efforts in the nations bordering the waterway and its tributaries.
Prime Minister Viktor Orban, visiting the village of Kolontar, where homes and fields were coated with sludge, described the reservoir break as a disaster unprecedented in Hungary.
"If this had happened at night then everyone here would have died," he told the MTI news agency. "This is so irresponsible that it is impossible to find words."
Soldiers, emergency workers and volunteers dressed in mud-splattered protective gear kept shoveling out the muck Thursday, a process officials said could take months.
The long-term effects on the agricultural region were devastating, officials said. Some 2,000 acres of topsoil will have to be dug up and replaced because the highly alkaline sludge had killed off all the nutrients and organisms needed to keep the soil healthy, according to Illes, the environment minister.
It is still not known what caused a section of the reservoir to collapse, unleashing a torrent of some 35 million cubic feet (1 million cubic meters) of sludge that killed at least four people and left three missing. More than 150 people were treated for burns and other injuries, and 11 remained in serious condition Thursday.
However, meteorologists at AccuWeather.com suggested unusually high precipitation might have been a factor, saying spring and summer rainfall in areas of central Europe from Poland to southern Hungary was more than 200 percent above normal.
The walls holding back the sludge may have been weakened by the rain, contributing to the breach that released the spill, the agency said.
MAL Rt., the Hungarian Aluminum Production and Trade Company, which owns the Ajkai Timfoldgyar plant where the spill occurred, has rejected criticism it should have taken more precautions at the reservoir.
However, Hungary's National Investigation Office, which is investigating the spill, said it planned to look into whether on-the-job carelessness was a factor.
The huge reservoir, more than 1,000 feet (300 meters) long and 1,500 feet (450 meters) wide, was no longer leaking by Thursday and a triple-tiered protective wall was being built around its damaged section. Guards were posted to give an early warning in case of any new emergency.
That did not calm the fears of villagers who lived through the disaster, many of whom said they planned to leave.
Etel Stampf was in her backyard when the first waves of the flood hit her home in Kolontar. She climbed on the roof of her pigsty to survive, but the flooding was so high that one of her legs was badly burned as it dangled in the caustic water.
"If I don't die now, I never will," the 76-year-old woman recalled thinking as she clung to the fragile structure.
"We worked so hard for years to have something for ourselves and now it's all gone," Stampf said. "I don't want to stay here. Ten years from now there will be nothing left of this town."
Associated Press writers Pablo Gorondi in Budapest and Alison Mutler in Bucharest, Romania, contributed to this report.