Fort Mill Times

Experts say Lake Wylie flooding unlikely

Mill Creek shows water high levels last week as land normally visible is covered. About a month ago, the creek was dry with grass growing due to the drought.
Mill Creek shows water high levels last week as land normally visible is covered. About a month ago, the creek was dry with grass growing due to the drought.

What a difference a month makes. Well, a month and a hurricane.

On Sept. 30, Lake Wylie sat almost 6 feet below full pond, much closer to its critical low water mark than high. Drought signs covered the area. The Catawba-Wateree River Basin Advisory Group planned a drought update. Then came Hurricane Joaquin and weeks of clouds behind it.

When the advisory group met Oct. 30, the lake sat more than a foot above target level and rising. Talk turned from drought to flooding.

On Nov. 4, the lake level is 3 inches away from full pond.

Jeff Lineberger, licensing director with Duke Energy, said storms that caused widespread flooding in Columbia and other parts of the state could’ve barreled down on the Catawba system.

“On this Catawba-Wateree system,” he told the advisory group, “we were profoundly fortunate.”

Which raised the question, how susceptible to flooding are areas like Lake Wylie?

“The drought has really been more of a problem in our area than flooding,” said S.C. Sen. Wes Hayes. “It’s probably a good thing we had capacity in our lakes that we could release it downstream.”

During the summer drought, Duke fielded questions about why it released so water when lakes levels were low. There isn’t a single answer. Water flows are needed for downstream users, aquatic habitat and to comply with federal regulations. The extra capacity from lower lakes helped during heavy rains.

The company has a well-outlined protocol for handling drought. Methods were developed as part of a 2006 federal hydroelectric relicensing process, and implemented despite the company still waiting for license approval. Flood prevention isn’t as detailed.

“None of its individual projects are what you’d call flood control projects,” Lineberger said of the pending license. “But this little bit of storage left over that we don’t intend to use, really can be beneficial.”

Target levels never rise more than 2 or 3 feet from full pond on Catawba lakes. When heavy rain falls, the company can move water ahead of the forecast to create more capacity.

It’s not an easy task. If Duke runs more water than rain replenishes, it could create new problems.

“If we would have started running that water a week before the rain got here,” Lineberger said of Joaquin preparation, “we could have put ourselves immediately into Stage 3 drought conditions. And then if that rain didn’t come, oh man.”

The drought status remained at Stage 1 of the 0-4 low inflow protocol rating Duke uses. Stage 1 is voluntary water-use restrictions. Stage 3 is mandatory, one step away from the worst including federal intervention.

Barry Gullet, director of Charlotte-Mecklenburg Utilities, said a missed forecast could have extreme consequences if Duke pumps out water the clouds never replace.

“It’s affecting industry and housing and landscape companies, all those folks,” he said.

Water takes 48 hours to get from Lake James to Lake Wateree when the company is moving it steadily. An advantage the company has, and one they say keeps the area safe from flooding, is the 11-lake system. Lakes Wylie and Norman, in particular, can hold massive amounts of water in those few feet between target elevations and full pond. Wylie is more likely to help upstream and downstream lakes from flooding than it is to flood itself.

“If we had Wylie at 100 (full pond), that would mean everything upstream would be at 100, and probably everything downstream would be at 100,” Lineberger said. “We operate this whole thing as a system.”

The new license sets up rules that should improve flows for aquatic habitat, increase the amount of available water in the system and make the Catawba more drought resilient, said Mark Oakley, relicensing project manager. Duke will “release more water, and on a continuous basis,” compared to the way it operated before relicensing.

“The good news is, we’ve been doing that voluntarily since 2006,” Oakley said.

John Marks: 803-831-8166