KOLONTAR, Hungary (AP) -- The toxic red sludge that burst out of a metals plant reservoir and inundated three villages reached the mighty Danube on Thursday, but an Hungarian emergency official said no immediate damage was evident on Europe's second-longest river.
The European Union and environmental officials had feared an environmental catastrophe affecting half a dozen nations if the red sludge, a waste product of making aluminum, contaminated the 1,775-mile (2,850-kilometer) long Danube.
The reservoir break Monday disgorged a toxic torrent into local creeks that flow into waterways connected to the Danube. Creeks in Kolontar, the closest town to the spill site, were swollen ochre red Wednesday and villagers said they were devoid of fish. Kolontar is 45 miles (70 kilometers) south of the Danube.
The red sludge reached the western branch of the Danube early Thursday, Hungarian rescue agency spokesman Tibor Dobson told the state MTI news agency. He did not address concerns that the caustic slurry might contain toxic metals but said its pH content had been reduced to the point where it was unlikely to cause further damage to the environment.
Dobson said the pH content, which officials earlier said was at 13, was now under 10 and no dead fish had been spotted where the slurry was entering the Danube. The National Disaster Management Directorate, in a separate statement, said the pH value was at 9.3 and constantly decreasing. Normal ph levels for surface water range from 6.5 to 8.5.
South of Hungary, the Danube flows through Croatia, Serbia, Romania, Bulgaria, Ukraine and Moldova before emptying into the Black Sea.
At the Croatian village of Batina, the first site after the Danube leaves Hungary, experts were taking water samples Thursday which they will repeat daily for the next week, the state-run news agency HINAS reported.
In Romania, water levels were reported safe Thursday, with testing being carried out every three hours, said Romanian Waters spokeswoman Ana Maria Tanase. She said the Danube water had a pH of 8.5, which was within normal levels, but tests were being done to check for heavy metals.
Hungarian Prime Minister Viktor Orban visited the three villages coated by the red sludge Thursday and declared the worst-hit area a write-off, saying he sees "no sense" in rebuilding in the same location.
Local officials said 34 homes in Kolontar were unlivable. However, furious residents said the disaster had destroyed the whole community of 800 by making their land valueless.
Angry villagers gathered outside the mayor's office late Wednesday and berated a senior official of MAL Rt., the Hungarian Aluminum Production and Trade Company that owns the Ajkai Timfoldgyar plant, demanding compensation.
"The whole settlement should be bulldozed into the ground," bellowed Janos Potza. "There's no point for anyone to go back home."
"Those who can, will move out of Kolontar. From now on, this is a dead town," fumed Beata Gasko Monek.
It is still not known why part of the reservoir collapsed. Authorities have ordered a criminal inquiry into the accident, which killed at least four people, injured 120 and left three people missing amid an estimated torrent of 35 million cubic feet (1 million cubic meters) of toxic waste.
A spokeswoman for the National Police said investigators would 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 and a triple-tiered protective wall was being built around its damaged section. Guards have been posted at the breach to give an early warning in case of any new emergency.
The sludge spill is "one of the top three environmental disasters in Europe in the last 20 or 30 years," said Herwit Schuster, a spokesman for Greenpeace International.
The International Commission for the Protection of the Danube, which manages the river and its tributaries, said the sludge spill could trigger long-term damaging effects for both wildlife and humans.
"It is a very serious accident and has potential implications for other countries," Philip Weller, the group's executive secretary, said from Brussels.
Weller said factories and towns along the Danube may have to shut down their water intake systems. He said large fish in the Danube could ingest any heavy metals carried downstream, potentially endangering people who eat them.
Red sludge is a byproduct of the refining of bauxite into alumina, the basic material for manufacturing aluminum. Treated sludge is often stored in ponds where the water eventually evaporates, leaving behind a dried red clay-like soil.
Hungarian company officials have insisted the sludge is not considered hazardous waste according to EU standards. The company has also rejected criticism that it should have taken more precautions at the reservoir.
Alumina plants are scattered around the world, with the 12 largest concentrated in Australia, Brazil and China. The plant in Hungary ranks 53rd in the world in production, according to industry statistics.
Associated Press writers George Jahn, Greg Katz in London, Alison Mutler in Bucharest, Ramit Plushnick-Masti in Houston contributed to this report.