PSI: Dam failure feared during Catawba floods
Floods earlier this month stemming from heavy rains in the North Carolina mountains were the worst we've seen since 2004. WBTV has learned there was a risk of a much bigger problem. A possible failure of the Oxford Dam holding back the waters of Lake Hickory.
Over a 72 hour period starting May 3rd the headwaters of the Catawba River were hit with up to 11 inches of rain. It was much more than forecasters expected. The runoff down the mountains was pushed Lakes James and Rhodhiss higher. Duke Energy, which controls the water levels through a series of dams, made the decision to raise a gate on the next lake in the chain, Lake Hickory.
The gate was raised 3 feet around 6:30 p.m. on Sunday May 5th. Property owners downstream on Lookout Shoals Lake were notified by Duke Energy their lake would rise to just over full pond. It was expected to reach 101.5 feet of elevation.
As the evening moved along, it was clear one gate at 3 feet, wasn't enough. Oxford Dam was going to have to opened wider to handle the water still coming downstream.
It is when the problem hit. The gate wouldn't budge. Duke Energy couldn't open it anymore.
"The hoist that is used to move that gate didn't function the way it should have," said Duke Energy Spokesperson Paige Sheehan. "They quickly brought in troubleshooters."
It was 7 a.m., Monday May 6th, and Lake Hickory was nearing full pond. Just an hour later at 8 a.m. it reached it. Water began spilling over the dam and down the auxiliary spillway.
How serious was the problem?
"The operation of the system was all perfectly safe," said Sheehan.
But three years ago, when WBTV investigated high water on Lookout Shoals, Duke Engineer George Galleher told us water topping at Oxford was not an option.
"We won't allow Lake Hickory, or Oxford Hydro to go over a hundred (feet)," said Galleher. "We raise the gates."
It was a safety issue. A person has to get on the dam to hook the gate. They can't do it if water is going over top. Thankfully, Duke had hooks on the one gate partially open.
The Federal Energy Regulatory Commission (FERC) said in a letter explaining the 2010 flooding on Lookout Shoals that if the lake tops 100 feet "before the spillway gates were opened, the inability to lift spillway gates...could potentially result in a dam safety emergency."
But even knowing that, Wayne King, regional engineer for FERC tells WBTV the condition at Oxford was "serious."
"(Duke) had one gate partially open with no control," said King.
WBTV asked Duke's Sheehan why there appears to be a disconnect between what Duke was saying about the problem and what King had said.
"What I said was we had an operational challenge for a period of time that we were able to effectively address," said Sheehan.
It was serious enough that Duke contacted FERC right away Monday morning. Twenty minutes later the company called again. Duke told King it may have to go to "Condition B" at the dam. A rare declaration that would signal a higher level of alert to local emergency managers.
According to Duke's Emergency Action Plan the condition meant a "potentially hazardous situation is developing - there is no failure."
FERC says it is a situation "where a failure may eventually occur." It "should convey the impression that some amount of time is available...before failure of the dam is considered a foregone conclusion."
The issue facing Duke was the water upstream was still rising and the gate was still stuck. Lake James which dwarfs Lake Hickory was still at least 12 hours away from cresting.
It raised another question, did the problem at Oxford affect Duke's ability to minimize the impact downstream?
"Absolutely not," said Sheehan. "Downstream impact was minimal."
The gate was finally fixed around 10 a.m. Three hours after the problem was identified, but Lake Hickory continued to rise. The lake would eventually hit 101.7 feet. The highest the lake had been in more than 70 years. The decision was made to fully open two more gates. The water rush was on.
Sheehan maintains the data shows there was minimal impact downstream. The fact is Lookout Shoals lake went from full pond to seven feet over in just six hours. Homes were flooded, docks were submerged, boats and furniture were swept away.
And the crisis wasn't over. The water still needed to get through Lakes Norman and Mountain Island. Duke put out a notice on its website Monday afternoon at 2:30 p.m. Mountain Island was expected to remain "at or below 102.5." It also proved to be wishful thinking.
"They (Duke Energy) were terrible 9 years ago," said property owner Barry Stubbs. "And they were terrible this time letting us know how high the water was going to go."
Overnight, at 1:20 a.m. new messages went out. The lake was now expected to "remain below 105 feet." A level of moderate flooding, but not everyone got the message.
Flood waters arrived by dawn. Cathy LaRoche is the Mountain Island Lake Commissioner. She strapped on a life jacket to save what she could from her dock.
"It came up a lot faster than I expected it really did," said LaRoche.
At 6:55 a.m. the Charlotte Fire Department sent out a Tweet saying voluntary evacuations were underway. Yet, a flood warning from the National Weather Service wouldn't come for three more hours. It was finally issued at 9:59 a.m.
"You're right that came late. I don't know quite why that was," said LaRoche.
The National Weather Service doesn't forecast for the Catawba River, because it says Duke controls the variables like how much water is being released down river.
The Weather Service, however, will issue warnings based on data Duke provides. In this case, forecasters told WBTV the information was slow in coming.
"I am very confident that Duke Energy provided information to the National Weather Service that they needed to put out appropriate information to the public," said Sheehan.
After our interview with Duke Energy, the company called the National Weather Service. One of the forecasters we talked to earlier, who said information was slow in coming in, then called us. Now, we were told the NWS has a great relationship with Duke and forecasters can get all the information it needs.
If so, why was the flood warning so late in coming out? We were told river statements had been issued for the expected high water along the middle Catawba River. The problem with those, they don't set off weather alarms and don't get crawled on the bottom to TV screens.
FERC has already been in contact with Duke Energy. Regulator want a full "after action report." It must be filed by Duke by mid-June.
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