Water levels at Lake Johnson in Raleigh are being lowered in advance of a tropical system and what's expected to be a wet weekend.
The decision comes as several inches of rain are likely throughout North Carolina over the next five days. The lake has been lowered by about 2.5 feet as of midday Friday. City stormwater officials have decided to keep lowering Lake Johnson through noon on Saturday, when levels are expected to have dropped by 3.75 feet. Crews will then reassess if efforts need to continue.
Other WRAL Top Stories
"What we can do by lowering the lake is to capture that runoff and keep it from going downstream and try to prevent as much flooding as possible downstream," said Kelly Daniel, who works as Raleigh's flood early warning system manager."
Rose Lane in southeast Raleigh is a downstream community that is no stranger to what can happen when Walnut Creek floods.
"It probably has more of a tendency to flood than any other road along Walnut Creek, and if that road does flood, that community to the south of the creek, it will cut that community off," Daniel said.
Raleigh leaders rely on the Flood Early Warning System to decide when water levels should come down. The system uses gauges and modeling to predict flooding conditions before and during a storm.
"We can run those rainfall models through a 'what if' scenario that has...hydraulic modeling built into it. It'll show us what potential rise we could see on the creek levels in Raleigh," Daniel said. "Because it takes so long to lower it, we decided let's go ahead and start lowering it. It takes a foot a day, and that means every day, we'll be able to evaluate and see if we need to continue lowering it or not."
Wake County tracks water levels through a US Geological Survey monitoring system. The county manages ten flood control reservoirs within the Crabtree Creek watershed.
"Staff has not preemptively lowered water levels in the reservoirs, but two sites were already lowered due to scheduled maintenance projects," said a county spokesperson in an email to WRAL.
WRAL has asked the US Army Corps of Engineers if similar water lowering efforts are underway at Jordan or Falls lakes and has not yet received a response. The agency partially oversees operations at the two sites.
The WRAL weather team said tropical impacts are increasingly likely in the Triangle next week. On Monday and Tuesday, we could see another system (which would be Imelda) making landfall in South Carolina that would bring us rainbands.
Anywhere from 3 to 5 inches of rain is expected in central and eastern North Carolina over a five-day period.