With 2020 on pace to set an all-time rainfall record, the Tennessee Valley Authority is balancing flood-control concerns with other demands on its lakes and rivers, a TVA official said Tuesday.
Rainfall totals through the first nine months of this year are well above average across TVA’s 41,000-square-mile service area and rapidly approaching the record established in 2018, according to James Everett, senior manager of the TVA River Forecast Center in Knoxville. His comments came during a virtual media briefing.
“We’ve already seen 58 inches of rain; that’s 7 inches more than we see during a normal 12-month period. We are trending well above normal,” Everett said. “If we continue with the current trajectory of this record-setting pace, we will eclipse the 2018 rainfall record, which was 67 inches across the valley. If we get normal rainfall in October, November and December, we will definitely eclipse that 67-inch mark of 2018.”
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Those figures are averages for the TVA service area. The National Weather Service office in Morristown, Tennessee, reported 47.1 inches of rain since Jan. 1 for the Tri-Cities area, which is nearly 15 inches above normal for the end of September. That is more than 5 inches above what the NWS reported on this date in 2019.
Last year was the region’s second wettest on record, with an average of 66.5 inches of rainfall across the TVA service area, Everett said.
South Holston Lake’s reservoir level was above normal Tuesday, at 1,722 feet above sea level. Boone Lake was at 1,354 feet, while Watauga Lake was at 1,956 feet and Fort Patrick Henry stood at 1,260 feet, according to the TVA website.
While reservoir lakes like South Holston and Watauga are being drawn down, electricity generation is being limited, he said.
“We are scheduling just a few hours of generation a day,” Everett said. “This time of year, there are a lot of folks doing some trout fishing below South Holston, so a lot of times we’re trying to dial back those releases on the weekends and during the week when we can.
“We’ve had such active rains, we want folks to be aware and understanding that we are higher than normal at South Holston and we will look for opportunities to dial back the generation flow, but we also have to be mindful that — with lake levels high and more rain coming — we need to run at least some generation to get us going in the right trajectory for the drawdown.”
Demand for water is typically highest in August, Everett said, but much less in January to April, when the region typically receives 60% of its annual rainfall and runoff.
“We need to start now releasing water from some of these reservoirs to build flood storage capacity. We release water at a controlled rate in October and November to get those lake levels down by December so our tributary reservoirs like South Holston and Watauga are ready to store water,” he said.
Three years of record rainfall hasn’t prompted TVA to make any operational changes.
“It has meant a lot higher than normal lake levels. We saw that this year at South Holston and Watauga and that’s by design,” Everett said. “Those reservoirs were designed and built to accommodate very large, dense rainfall events that we’ve seen — both this past year and the previous two years. We’ve seen higher flows below the dams, but our overall operating policy has not changed.”