A deluge of rain in the past two weeks has swollen the Tennessee River, shutting down barge traffic in Chattanooga for nearly two weeks and flooding low-lying areas in West Tennessee late this week after flooding last week in Nashville.
Rainfall in March across the Tennessee Valley was nearly double the normal levels for the month, with most of the precipitation coming in the past week from storms that dumped more than 7 inches of rain on Nashville last week and nearly as much on Tuesday in parts of West Tennessee.
"The month of March was extremely wet," said Darrell Guinn, operations support manager with the Tennessee Valley Authority River Forecast Center in Knoxville. "We had almost three weeks in a row where we saw significant rain events come through the valley, and [those] boosted our overall rainfall totals so far this year."
TVA is spilling water through all nine of its main river dams to help bring down rain-swollen reservoirs, which rose in some instances above normal summertime pools. TVA typically doesn't raise its storage lakes above Chattanooga in the Tennessee River basin until June 1.
TVA is now pouring about 787,000 gallons of water a second through its Chickamauga Dam in Chattanooga, raising the level and flow of the Tennessee River so river barges are not allowed to navigate now through the Tennessee River gorge west of Chattanooga or through the Scenic City.
Across the Tennessee Valley, river navigation has been challenged this spring by heavy rains.
"Barges are still passing through Wilson, Pickwick and Guntersville, but it's tricky with TVA pushing so much water through these dams," said Clive Jones, executive director of the Tennessee River Valley Association, which represents the barge industry that uses the Tennessee River to ship more than 50 million tons of cargo a year. "But with all this rain, we're not moving now in Chattanooga or on the Cumberland River at the Cheatham Dam. Everything is getting backed up now."
The main locks at the Cheatham and Wilson dams are also scheduled to be shut down for more than two weeks for maintenance work in late April and May.
* 12.06 inches of rain fell last month in Chattanooga, 7.08 inches above normal
* 9.86 inches of rain fell across the entire Tennessee Valley last month, 4.83 inches above normal
* 787,000 gallons a second are flowing through the Chickamauga Dam, raising the Tennessee River levels and flow to limit barge and boating activity on the river. The spilling at Chickamauga is projected to continue through next week.
Source: Tennessee Valley Authority
Guinn said Whitesburg and Florence in Northern Alabama and Savannah in West Tennessee are already at flood stage with river levels expected to crest on Friday.
"We are in flood control operations with the Corps of Engineers, and we are coordinating our releases from the Kentucky Dam to help control floodwaters downstream on the Ohio River," Quinn said.
TVA reservoirs such as Fontana, Norris and Cherokee help store water during major rain events and prevent flooding in riverfront cities such as Chattanooga. Parts of Chattanooga along the river would now be underwater without the 49 dams erected along the Tennessee River and its tributaries by TVA and the U.S. Army Corps of Engineers over the past century.
Last year when the Tennessee Valley received a record 70.33 inches of rainfall, TVA estimates it averted nearly $800 million in flood damage that would have otherwise hit Chattanooga as the drainage point for much of East Tennessee, North Georgia and parts of Virginia, Kentucky and North Carolina.
The region should get a reprieve from the rain for the next week, although the dry weather is bringing a cold start to the month of April. The National Weather Service predicts temperatures will be at or below freezing both Friday and Saturday mornings, only slightly above Chattanooga's record low for April 2 of 25 degrees Fahrenheit.
"We're not expecting any significant precipitation anytime for at least the next seven days," said Sam Roberts, a meteorologist for the National Weather Service in Morristown. "It's going to be much cooler than normal Friday with a high of only about 50 degrees, but it should warm up this weekend and into early next week when we could see highs again in the 70s."
Despite a drier than normal January and a more typical February for rainfall, the heavy March rains boosted rainfall so far in 2021 to 17.99 inches across the Tennessee Valley, or 4.22 inches above normal. This is the fourth consecutive year of above-average rainfall.
Last year was a record high year for precipitation in the Tennessee Valley, with rainfall averaging more than 21 inches above normal.
Contact Dave Flessner at firstname.lastname@example.org or 423-757-6340.