The danger at Oroville Dam, America's tallest dam, has not passed yet.

Last week, the heavy rain has caused the level of Oroville Lake to rise, prompting officials to use an emergency spillway for the first time in almost 50 years on Saturday.

Instead of solving the dilemma however, it became worst as the engineers found an eroded section of the spillway. The 200-foot long, 30-foot deep hole prompted the forced evacuation of hundreds of thousands county residents that might be affected if the structure of the emergency spillway collapses.

It is estimated that if it collapses, repairs could take as long as 90 days, and cost upwards of $200 million, Science Alert reported.

"It's complex and rapidly changing, so we are doing everything we can to support Butte County and the local authorities to be able to addrrss most folks who have been displaced" said Mark Ghilarducci, director of the state Office of Emergency Services, in an interview with Sacramento Bee."

The erosion could result into an uncontrolled flood that could wash down to Oroville and other towns in Yuba, Sutter and Butte counties. Yuba City is the biggest city evacuated.

To prevent the havoc, the officials used bags of rocks to cover the hole of the auxiliary spillway and continued to release waters at a rate of 100,000 cubic feet per second to lower the water level, LA Times reported. And while authorities have already announced that the situation steadied for a bit and the hole is starting to dry up, the danger is not over yet.

A new storm is expected to land on the area this week and officials concluded that the repairs might not be able to withstand it. As such, the evacuees are still not allowed to go back to their homes.

Meanwhile, as of Feb. 14, the Flood Warning continues for Sacramento Rivers at Vina Woodson Bridge, Tehama Bridge and Ord Ferry.