Fox News Weather Center

Multiple Dam Failures Aggravate Dangerous Conditions in Flood-Ravaged South Carolina

After historic rainfall across South Carolina, dam breaches and failures have aggravated already dangerous flooding problems.

Nine dams have breached or failed completely as of 11 a.m. EDT Tuesday, according to South Carolina Emergency Management. Another was intentionally breached to alleviate pressure.

Aerial Footage Shows South Carolina Neighborhood Cut off by Flooding

Mandatory evacuations were executed in areas of major concern. Residents near the Overcreek Dam in Richland County were evacuated on Monday.

Still, many residents sit in areas susceptible to additional flooding.

"Don't let the sunshine fool you," South Carolina Gov. Nikki Haley said on Tuesday, stressing that the next 36 to 48 hours still pose threats to public safety.

Haley said officials are on the ground assessing vulnerable dams in various areas. Evacuation orders may continue to be put into place in order to provide safety for residents in those vulnerable areas.

"The combination of multiple days of torrential rainfall alone may have contributed to softening up earthen dams," AccuWeather Senior Meteorologist Alex Sosnowski said. "The long duration of the high water is putting pressure on the earthen dams to the point of failure."

The risk for failures may continue even where water levels have already peaked in central South Carolina due to weakening of earthen dams, Sosnowski said.

Prior episodes of rain in September saturated the ground, enhancing the risk for flooding.

Officials in the hardest-hit areas have gone door-to-door, ready to evacuate those in need.

The multiple breaches and failures contributed to severe flooding and dangerous conditions.

"This will not be a short or easy recovery, but we will get through it and get through it together," Haley said in a statement Monday.

After a verbal request, President Barack Obama signed a disaster declaration for South Carolina to expedite federal assistance to the flood-ravaged state.

"Sporadic localized areas actually had significant rain during September, moistening the ground and causing some water levels to begin to rise," Sosnowski said.

Before the rounds of rain in September and October, 65 percent of South Carolina was experiencing moderate drought conditions.

In some cases, dams in South Carolina had not been tested since Hurricane Hugo in 1989.

A citywide boil water advisory is still in effect in Columbia with many safe drinking water distribution sites throughout the area.

Creek Rushes Over Road in Columbia, South Carolina