The high-alert warning level for the area surrounding Oktibbeha County Lake will continue through the weekend while six diesel-fueled pumps lower the lake to a safer water level, Emergency Management Agency Director Kristen Campanella said Saturday.
Meanwhile the dam holding the lake’s water from flooding more than 100 homes is still intact, five days after authorities deemed a breach “imminent.”
“We don’t know how much rainfall we’re getting (this weekend), and every half-inch of rainfall is four feet of water in the lake,” she said. “We can get a better sense of it on Monday, because everything that flows through here takes 24 to 36 hours to get through this watershed, so with the rain we’re getting (Saturday), we may start seeing it on Monday.”
The water level in the lake has dropped about 18 inches since Thursday, thanks to pipes the county has been using to pump off water into a nearby spillway and the fact the area has seen very little rain in the last few days, Oktibbeha Sheriff’s Office Capt. Brett Watson said. Relieving the water pressure on the dam could prevent a breach that could flood 17,500 acres of nearby land and force about 250 people to evacuate at least 130 households.
On Friday night, Birmingham, Alabama-based Herc Rentals delivered additional pumps now being used to lower the water level even faster.
The portion of County Lake Road between Riviera Road and Walter Bell Road closed indefinitely when crews began installing the pumps. They worked from almost 9 p.m. Friday to almost 5 a.m. Saturday, Campanella said. The pumps use between 15 and 22 gallons of diesel per hour, and Rackley Oil Company of Starkville provided the fuel, she said.
County Engineer Clyde Pritchard and the U.S. Army Corps of Engineers have been monitoring the levee since Tuesday. Water was seeping between the dam and the bedrock underneath it, pushing sand boils to the surface and forming a crack on the slope. The county issued a warning and a recommendation that area residents evacuate. The warning would upgrade to an emergency and spark a mandatory evacuation if water starts streaming out of the levee or if the mudslide in the seeping area of the levee reaches the pavement on County Lake Road.
Pritchard initially estimated it would take 22 to 24 days to lower the water level of the lake by five feet, possibly eliminating the danger of imminent dam failure, if the area receives no additional rainfall and if the pumps can drain the lake at a rate of 25,000 gallons per hour. By Saturday, he changed his estimate to 14 days.
The pumps can work at 30,000 gallons per hour, and the three 8-inch pipes and one 10-inch pipe that had already been siphoning water off the lake since Tuesday can remove an additional 20,000 gallons per hour.
After the water level recedes, engineers will cut off the dam’s primary outlet valve in order to keep the water level low. The valve was completely underwater Thursday afternoon but was visible Friday.
Authorities also found a new sinkhole in the levee at the Oktibbeha County Lake late Thursday afternoon and another one Saturday morning, but neither had water in it, Campanella said.
District 1 Supervisor and board president John Montgomery praised county officials and employees for being “proactive, not reactive” in working to reduce the water level. For the past several months, the county has been seeking federal and state funds to replace the levee, emergency spillway and floodgate valve, a roughly $8 million project.
“We’ve been seeking it just as hard then as we are now, and I hope that the people who have the ability to help us out do realize what we’re dealing with,” Montgomery said.