Dam Failure

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South Carolina has relatively few natural ponds and lakes. Virtually all ponds and lakes in the state were created by the construction of a dam. There are estimates of over 10,000 man-made dams in South Carolina, but the actual number may be as high as 50,000. The vast majority of dams are below the size threshold for state regulation, which is discussed at the South Carolina Department of Environmental Services (SCDES) Dam Safety Program’s website at: https://des.sc.gov/dams.

 

The U.S. Army Corps of Engineers (USACE) has a dedicated program to maintain an inventory of all state-regulated and federally-owned or federally-regulated dams in the United States. This inventory contains over 90,000 dams and can be viewed at the USACE’s National Inventory of Dams (NID) website at: https://nid.sec.usace.army.mil/

Before a Dam Failure
  • Know your risk. Do you live downstream from a dam? Is the dam a high-hazard or significant-hazard potential dam?
  • Significant Hazard Dams are inspected on a 3-year cycle and High Hazard Dams on a 2-year cycle. The Emergency Action Plans (EAPs) are developed and maintained by the dam owners, identify potential emergency conditions at a dam, and specify pre-planned actions to be followed to reduce property damage and loss of life. Contact the dam owner if you have any questions concerning the EAP for a specific dam.
  • Know your evacuation route should you be told to evacuate. To find out if your property is located in a dam breach inundation zone or to find out the location and classification of all state-regulated dams, visit https://gis.dhec.sc.gov/scdams
  • Review your insurance policy. Flood coverage is not part of most homeowner, mobile home or renter’s insurance policies. There is a 30-day waiting period for coverage to take effect.
During a Dam Failure
  • If told to evacuate, secure your home. If you have time, bring in outdoor furniture and move essential items to an upper floor. Turn off utilities at the main switches or valves, if instructed to do so. Disconnect electrical appliances. Do not touch electrical equipment if you are wet or standing in water.
  • Do not walk through moving water. Six inches of moving water can make you fall. If you must walk in water, walk where the water is not moving. Use a stick to check the firmness of the ground in front of you.
  • Do not drive into flooded areas. If floodwaters rise around your car, abandon the vehicle, and move to higher ground if you can do so safely. You and the vehicle can be quickly swept away.
After a Dam Failure
  • After a flood, listen for official sources to learn whether the community’s water supply is safe to drink.
  • Avoid floodwaters; water may be contaminated by oil, gasoline, or raw sewage.
  • Be aware of areas where floodwaters have receded. Even if the roadway of a bridge or elevated highway looks normal, the support structures below may be damaged.
  • Stay clear of downed power lines and report them to your power company.
  • Use extreme caution when entering buildings; there may be hidden damage, particularly to foundations. Stay out of any building that is surrounded by floodwaters.
  • Clean and disinfect everything that got wet. Mud left from floodwater can contain sewage and other harmful chemicals.
  • If injured, seek medical attention when safe to do so.
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