(Source : Ap) The wall of a reservoir filled with caustic red sludge will inevitably collapse and unleash a new deluge of red sludge that could flow about a half-mile (1 kilometer) to the north, a Hungarian official said Sunday. That would flood parts of the town already hit by the industrial waste on Monday but stop short of the next town to the north. Environmental State Secretary Zoltan Illes said recently discovered cracks on the northern wall of the reservoir at the alumina plant have temporarily stopped widening because of favorable weather conditions but will continue to expand, especially at night. Disaster agency spokesman Tibor Dobson said engineers didn't detect any new cracks overnight, and the older cracks were being repaired, but that it was too soon to consider lowering the current state of alert. Protective walls were being built around the reservoir's damaged area to hold back any further spills and a 2,000-foot (620-meter) long dam was under construction to save the areas of the town of Kolontar not directly hit by Monday's disaster. "I would describe the situation as hopeful, but nothing has really changed," Dobson told The Associated Press. "The wall to protect Kolontar is planned to be finished by tonight, but it will likely be several days before residents may be able to move back." Nearly all of Kolontar's 800 residents were evacuated Saturday, when Prime Minister Viktor Orban said the north wall of the massive storage pool — which is 24.7 acres (10 hectares) in size — was expected to "very likely" collapse after cracks were detected at several points along the dam. The roughly 6,000 residents of neighboring Devecser, just north of Kolontar, were told by police Saturday to pack a single bag and get ready to leave at a moment's notice.