Columbia could be left underwater if the Lake Murray dam breaks

Water flows from a Lake Murray dam gate in Columbia, South Carolina, Tuesday, Oct. 6, 2015. Despite improved forecasts, it will still take weeks for the state to return to normal after being hit by historic rainstorm.  (AP Photo/Chuck Burton)

Water flows from a Lake Murray dam gate in Columbia, South Carolina, Tuesday, Oct. 6, 2015. Despite improved forecasts, it will still take weeks for the state to return to normal after being hit by historic rainstorm. (AP Photo/Chuck Burton)

Photo of the AP file

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Lake Murray

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Experts say it’s unlikely, but a powerful earthquake in the Midlands could threaten the Lake Murray Dam and release up to 650 billion gallons of water.

If the two 213-foot-tall dams comprising the Dreher Shoals Dam facility – known locally as the Lake Murray Dam – were to fracture after a powerful earthquake, the resulting rupture would release an enormous amount of water. According to Kim Stenson, director of the South Carolina Emergency Division of Management and Dominion Energy.

The nearly 8,000-foot-long main dam, owned by Dominion Energy, provides hydroelectric power generated from Lake Murray’s 50,000 acres of water.

The Gervais Street Bridge could be under water, with places like the Vulcan Quarry or the Riverbanks Zoo being flooded.

John Davis, director of animal care and welfare at Riverbanks Zoo, told The State that there’s essentially nothing the zoo isn’t prepared for. The facilities and crew are well equipped and trained for any disaster, and Davis has ties to facilities in the Southeast should animals need to be evacuated.

Jimmy Fleming, vice president of permits and external affairs at Vulcan Materials, said the quarry had experienced flooding and natural disasters before and saw nothing to worry about.

“Nothing would happen on our end that we would consider catastrophic for anything else. In other words, if something went down on our site, it wouldn’t endanger anyone outside of our site,” Fleming said.

The dam has never suffered any damage or ruptures. But in the early 2000s, local officials were ordered to devise a strategy in the event of a dam failure..

The decision came after federal officials concluded the original dam would not survive the region’s potentially strongest earthquake. In their planning, they considered the worst case scenario: a flood would kick in, covering an area of ​​210 square miles up to 35 miles in half a day and raising the river level to 125 feet above normal. .

To address the potential calamity, a 213-foot-tall relief dam that could withstand a 7.3 magnitude earthquake was constructed.

“The relief dam was completed in 2005 at the Saluda Hydro facility as an additional security measure to withstand an unlikely event of major seismic activity,” Dominion spokesman Matthew Long said in a statement. an email. “The Saluda Hydro facility meets the Federal Energy Regulatory Commission’s stringent safety criteria, and both dams undergo frequent and thorough inspections to ensure they are ready to operate as designed.”

The largest recorded earthquake in South Carolina history – and one of the largest in eastern US history – hit Charleston in 1886 and is believed to have a magnitude of around 7 ,3 or more.

Experts say an earthquake of this magnitude in the Lake Murray region is unlikely, even after a recent string of quakes in South Carolina.

“The problem is there hasn’t been enough for us to really see any patterns at this point,” said Tom Pratt, research geologist for the US Geological Survey. “But we have no idea if it’s going to lead to something bigger or not, it’s unlikely.”

There are a number of fault lines that run beneath Lake Murray and South Carolina, but a fault line must be proven active before it is considered dangerous. The faults under Lake Murray have had no history of activity.

Several minor to moderate earthquakes have rocked South Carolina in recent months, with the largest reaching a magnitude of 3.5. Since December, at least 64 earthquakes have struck the Columbia area, usually between Elgin and Lugoff. Pratt said significant damage only occurs after a magnitude 6 earthquake.

Lake Murray Dam
Lake Murray Flach Dam, Tim

Instead of worrying about the disaster, Pratt urged residents to take the recent activity as a wake-up call to prepare.

“It’s always a reminder to keep emergency plans up to date,” Pratt said. “They (recent earthquakes) could die and do nothing. They could do something bigger. They could just go on as they are. We just don’t know.

South Carolina has a state emergency operations plan used for all disasters as well as plans for specific types of disasters. They include a dam-focused plan that interprets Dominion Energy’s disaster modeling. The South Carolina Division of Emergency Management used this data to create a plan that includes evacuation routes, evacuation zones and shelter locations.

According to a baseline of the model, more than 150,000 people would be affected, Stenson said.

“Now the likelihood of something happening affecting Lake Murray Dam is probably pretty low,” Stenson said.

Stenson said the Federal Energy Regulatory Commission orders periodic drills to test emergency plans. The last exercise took place in March 2021.

Emergency preparedness has changed a lot since the 2000s, Stenson said, with smart phones and alert systems. He said the main concern in South Carolina is hurricanes. Lake Murray and the likelihood of a breach are less of a concern, but still considered.

“SCE&G put a lot of time and effort into building this other relief dam. We’re pretty confident it’ll do the trick if we have a problem,” Stenson said.

South Carolina Electric & Gas Co. and its parent company, SCANA, were purchased by Dominion Energy in early 2018.

Brandon LaVorgna, the Division’s public information officer, said an update to the emergency plan will most likely be concluded next year and hasn’t been updated since about 2010. He was planned for an update but stopped when COVID became an obstacle. Stenson said it is now “in the limelight”, although not much has changed since its inception nearly 20 years ago.

He said the agency has tested flood plans and consistently executed them well, and he said the 2015 response to the historic Columbia flood showed that.

2015 brought a number of flooding issues after nearly 17 inches of rain fell on the Columbia area in just a few hours in October. Dozens of small dams failed in the 2015 rain bomb, with the failures showing how even small dam breaches can flood areas below.

To stay safe in an emergency, Stenson said to listen to local and state officials and devise a personal emergency preparedness plan of resources, education and evacuation.

“It’s very unlikely, I think, we think, but there’s always the potential to be flooded because of some sort of dam failure. They should have a plan,” Stenson said.

Stephen Pastis is a reporting intern for the state’s political and government team. He graduated from the University of South Carolina, where he served as the arts and culture editor of its college newspaper, The Daily Gamecock, and was a contributing editor to the Free Times Columbia.

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