Shoaling Halts Navigation On Tenn-Tom, BWT
High water on the Tennessee-Tombigbee Waterway has led to shoaling in amounts never before seen on the 34-year-old waterway. Bars near Mile 410, about two miles below Jamie L. Whitten Lock, and at Mile 357.5, just below Aberdeen Lock and Dam, have rendered the channel totally impassable in those areas.
The surge of high water on the Tenn-Tom followed record rainfall across the Tennessee River valley in February, and that’s after the region recorded its wettest year ever in 2018. As that water made its way down the Tenn-Tom, the waterway saw a rapid rise and fall.
A gauge on the Tombigbee River at Bigbee, Miss., saw a rise from about 6 feet on February 16 to 26 feet a week later. During that same time span, flow rates at the gage jumped from 2,000 cubic feet per second (cfs.) up to more than 60,000 cfs. By March 2, the river at Bigbee had fallen back to about 10 feet.
Likewise, at Aberdeen Lock and Dam, the river jumped from about 15 feet on February 18 to about 37 feet on February 24. On March 2, the river at Aberdeen was back around 16 feet, but the damage was done.
The Mobile Engineer District has dispatched its floating plant to the bar at Mile 410. Crews began working there on March 3. The Corps expected to open a 200-foot-wide pilot channel there by Saturday, March 9.
Unfortunately for businesses and operators on the waterway, it’s a different story downriver at Aberdeen. The bar at Aberdeen is huge and will take weeks to clear.
“It is a tremendous amount of material there—approximately 400,000 cubic yards,” said Justin Murphree, the Corps’ operations project manager for the Tennessee-Tombigbee Waterway.
According to the Corps, the shoal at Aberdeen extends a mile and a half below the lock and covers the entire channel with a depth of 6 feet or less. To put the size of the bar at Mile 357.5 into perspective, Murphree said it’s almost as much as the Corps dredges on the entire system in an average year (500,000 cubic yards).
“It is likely that we will still need to dredge that, or more, in other locations this year as well,” Murphree said.
Carl Dyess, chief of the technical support branch for the Mobile District, said the Corps spends about $3 million on dredging the Tenn-Tom in an average year, with an additional $2 million every four or five years on the divide cut between the Tennessee and Tombigbee rivers. He said the Corps’ current estimated need to address shoaling on the system is around $10 million.
“Funding is a major issue,” Dyess said. “We are reprogramming our entire budget.”
Dyess said the district has identified about $5 million so far, primarily by canceling a planned closure at Whitten Lock. Still, that’s only halfway there.
“Total need right now is approximately $10 million, so if we don’t get supplemental funds, then we will only be able to clear the most critical shoals, leaving lots of width restrictions,” Dyess said.
Mitch Mays, administrator for the Tennessee-Tombigbee Waterway Development Authority, along with Larry Merrihew, president of the Warrior-Tombigbee Waterway Association, were both in Washington, D.C., earlier this week, meeting with legislators and calling for a supplemental bill.
“The Corps is going to need emergency funding,” Mays said. “We’re going to beat the drum with our senators and congressmen.”
In the meantime, the Corps is securing a 24-inch cutterhead dredge to clear a pilot channel through the bar at Mile 357.5. The best-case scenario, though, is six weeks until that can be accomplished. The Corps estimates three weeks to get the dredge to Aberdeen and an additional three weeks to clear a pilot channel—and that’s assuming no further rain and no more issues in the system.
As of March 7, the Corps still had not been able to survey below the Tom Bevill Lock and Dam at the lower end of the Tenn-Tom, nor had surveys been done on the Black Warrior-Tombigbee Waterway. In addition, Coffeeville Lock, the southernmost lock on the Tombigbee, was still closed to navigation due to flooding. Anthony Perkins, operations project manager for the Black Warrior-Tombigbee and Alabama River Waterways Project, said at one time both Coffeeville and Demopolis Locks were closed to navigation.
“On our system, the Black Warrior-Tombigbee, we had to close Demopolis and then Coffeeville due to flood waters inundating the lock miter gate machinery,” Perkins said. “The water levels got high enough at both locks to go over the lock walls.”
Demopolis Lock reopened for daylight hours on March 4, then for normal 24-hour operation as water levels continued to drop. Perkins said the fall at Coffeeville would take several more days because of its location on the system.
Moving a dredge to the Tenn-Tom will hinge on Coffeeville reopening and completion of surveys on the waterway.