(CNN) -- Residents who were evacuated from a Hungarian village because of last week's toxic sludge were allowed back home Friday, a government spokeswoman said.
The 500 inhabitants of Kolontar were able to move back home if they wanted, though the village remained closed to the media, said the spokeswoman, who asked not to be named because she was not authorized to speak to the media.
Construction crews finished work this week on an emergency dam meant to protect against a second possible toxic spill from the MAL aluminum plant, located about 100 miles west of Budapest, the government announced.
Officials had earlier said they were certain the plant's reservoir wall would break again, inundating communities with deadly red sludge for a second time, but the government said so far, there has been no structural movement on the endangered section of the wall.
Around 1 million cubic meters of sludge spilled October 4 from the plant's reservoir, according to the country's president. It covered Kolontar and two other towns, killing nine people and injuring more than 100.
The sludge reached the Danube, Europe's second-largest river, raising concerns about contamination for countries downstream -- but officials say constant water monitoring has found no significant difference in pH value so far.
Environmental authorities are also continually monitoring the level of air pollution at 11 spots, the government said.
The chief executive of MAL, Zoltan Bakonyi, was briefly jailed this week, accused of public endangerment and harming the environment because of the spill. He was released Wednesday pending trial.
Bakonyi told CNN the company was in compliance with all Hungarian safety regulations. He said many of the problems with the reservoir and the toxins in it stretched back a quarter of a century, and he doesn't feel responsible because he has only been chief executive for two years.
He did say, however, he has a "moral duty" to help in the disaster's wake.