The toxic sludge that burst out of a Hungarian factory's reservoir continued to stain the river Danube a rusty red on Thursday after wreaking havoc on smaller rivers and streams.
The reservoir rupture on Monday disgorged a toxic torrent through three villages and streams that flow into waterways connected to the Danube.
Streams in the village of Kolontar, 45 miles south of the Danube and closest to the spill site, were still running red and local villagers claimed that they were totally devoid of fish.
Officials confirmed that 34 homes in Kolontar were completely uninhabitable because of the disaster.
But furious residents said the disaster had destroyed the whole village of 800 residents and made their land worthless.
It is still not known why part of the reservoir collapsed But the resulting breach allowed the toxic torrent - estimated at 35 million cubic feet of waste - to sweep through the villages, killing at least four people.
Three people were still reported missing.
Over 150 affected by the toxic flood were treated in hospitals and 11 remained in a serious condition on Thursday.
The European Union and environmental officials fear an environmental catastrophe.
Their concern is that a number of states could be affected if the red sludge, a by-product of aluminium smelting, contaminates the Danube, which is Europe's second-longest river.
Officials from several countries downstream - Croatia, Serbia and Romania - tested the river every few hours on Thursday, hoping that the Danube's huge water volume would blunt the impact of the spill.
Greenpeace International spokesman Herwit Schuster described the spill as "one of the top three environmental disasters in Europe in the last 20 or 30 years."