Dam and lake owners should begin preparing for Hurricane Matthew’s arrival by lowering water levels over the next several days, the S.C. Department of Health and Environmental Control urges.
Dam failures were caused by — and exacerbated — flooding that racked the Midlands in October 2015, almost exactly a year ago.
That disaster was caused by a pressure system that dumped more than 20 inches over parts of South Carolina in a 24-hour period. A hurricane can also threaten dam safety, according to DHEC, which regulates most of the state’s larger dams.
Hurricane force winds can topple trees causing large voids where trees are uprooted, the agency said in a news release Wednesday. Loss of soil from a dam can impact its structural integrity and can provide a path for water from the pond to exit in an uncontrolled manner. That can cause a dam to fail.
“Owners of reservoirs with functional gates or flashboards should considering operating them to provide additional storage for the anticipated rainfall,” said Jill Stewart with DHEC’s dam safety program. “If there is a dam downstream of your dam and you are lowering your water level, please call the owner of that dam and advise him or her about what you are doing. Before and after the storm has passed, any accumulated trash and debris should be cleared from spillways.”
DHEC has a system to automatically notify dam owners via voice call, text messages and email to take steps in preparation for the potential significant rainfall.
“Dam owners should be aware of the conditions at their dams during such events,” Stewart said. “If problems develop and failure of the dam might be imminent, the owner or operator of the dam should contact local public safety officials and downstream property owners.”