This story was updated at 11:20 a.m. on Tuesday, April 7, 2020.
The first three months of this year were the wettest start to any year in history across the Tennessee Valley, surpassing the previous record set in 1891.
A record 24.61 inches of rain drenched the region in the first quarter, raising river and lake levels, flooding some low-lying areas and shutting down some riverfront parks and river shipments through Chattanooga.
But for the most part, Chattanooga has avoided much flooding so far this year even with nearly half of a normal year's total rainfall coming in just three months.
That's because through the wet winter, TVA's network of 49 dams held back 2.2 trillion gallons of water in storage reservoirs upstream of Chattanooga, which is the drainage point in the Tennessee River basin for more than 20,000 square miles of East Tennessee, western Virginia, western North Carolina and North Georgia.
TVA estimates it averted nearly $1 billion of flood damage, including $772 million in damage in Chattanooga, that would have otherwise been caused by the heavy rains if the agency's dams and water management programs were not in place. Without those dams, TVA engineers estimate the Tennessee River would have risen 15.8 feet above what it reached on Feb. 11, leaving many riverfront, downtown and North Shore properties under water.
"The last three months have been an ongoing cycle of holding back water to avert flood damage, releasing a large amount to recover storage and balancing Tennessee River flows through a sustained above-normal rain event," said James Everett, senior manager of TVA's River Forecast Center.
Prior to TVA erecting its dams on the Tennessee River and its tributaries upstream of Chattanooga, heavy rains in 1917, 1867 and 1891 left much of Chattanooga underwater.
In Chattanooga, rainfall totaled nearly 26 inches during January, February and March, or nearly double the normal 14.9 inches of rain for the quarter, according to the National Weather Service. This year's rainfall in the first quarter was slightly below the record level set in 1990 when 26.67 inches fell in Chattanooga in the first three months of the year.
According to the National Weather Service's outlook for this spring, there is a higher probability of above-normal precipitation in the next three months, said Lyle Wilson, meteorologist in charge at the National Weather Service office in Morristown, Tenn.
During much of February and part of March, heavy flows on the Tennessee River forced the closure of the Nickajack gorge for commercial navigation. Downstream at Savannah, Clifton, Perryville and Johnsonville in Tennessee, thousands of acres of low-lying farmland were flooded this winter. River levels have crested or are expected to crest this week in those areas, but all will remain above flood stage for the next few days.
TVA spokesman Travis Brickey said additional spilling at TVA dams is still possible in coming weeks, depending on rainfall. TVA typically raises the lake levels in its storage reservoirs to summer pool levels by June 1, but lower main river reservoirs fill before the upper main river.
Fort Loudoun, Watts Bar, and Chickamauga have already begun transitioning from winter to summer pool with a target of May 16 to be at higher summertime levels.
"We are currently recovering flood storage on many of the tributaries that are well above their normal elevation for this time of year and will transition to a filling operation over the next few weeks," Brickey said.
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