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BOGOTA (Reuters) - Colombia has ordered the evacuation of nearly 5,000 people living along the Cauca river in the northern part of the country after construction problems at a hydroelectric dam prompted fears of massive flooding.

Heavy rains have increased water levels in the Cauca, which feeds the Ituango Dam in Antioquia province, the country’s largest-ever hydroelectric project. Problems with filling mechanisms and tunnels at the dam have authorities on high alert.

“We are working jointly with all institutions on the worst-case scenario, which is the breaking of the dam, which would provoke a huge flood in down-river municipalities,” said Jorge Londono, the head of Empresas Publicas de Medellin, the public utility company that owns the dam.

“That’s a catastrophic scenario,” Londono added.

The dam, which has not yet begun power generation, has cost nearly $4 billion to build and is meant to generate 17 percent of Colombia’s electricity needs. A total of 4,985 people from down-river areas were moved to shelters away from the flood zone, the Andean country’s disaster agency said in a statement.

Some 200,000 people live in the 12 towns and populated areas in Antioquia, Bolivar, Cordoba and Sucre provinces that could eventually be affected by possible flooding, authorities said.