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Rare dam water release in North Carolina triggers rainbows, winter ice show

A dam release in western North Carolina triggered a rare sight Tuesday as the spewing water produced rainbows and an icy show in the middle of winter.

After days of heavy rain saturated the area last week, river managers sought to create more storage room in Fontana Lake to prevent further flooding in the face of more rain in the long-range forecast, NBC station WBIR in Knoxville reported.  

"This event was so big, we got very high in the reservoir and we've got to move that water out," Tennessee Valley Authority General Manger of River Scheduling Chuck Bach told the Knoxville News Sentinel. "Sometimes we can't get enough water out fast enough through turbines, so we run the turbines first to generate hydroelectricity, and we augment it with either sluicing or spilling."

So for the first time in 13 years, the TVA began using a sluice tube behind the dam to lower water levels about one foot per day in the reservoir.  

That works out to about 128,000 gallons of water released per second, Bach said.

And to keep the force of the water from scouring out the bed of the Little Tennessee River, a ramp at the bottom of the sluice tube diverted the water, TVA spokesman Travis Brickey said.

In doing so, a sort of rooster tail of gushing water was created that gave off an enormous amount of spray that turned to snow and freezing droplets in the bitter air, which encased nearby trees and grass in a layer of ice.  

“It was its own winter weather maker,” Brickey said. “It was like a big, giant ice machine. It being so cold overnight and today, it froze to a lot of stuff.”

In the sunlight, the blowing mist also created a vivid rainbow effect.

“It made it more spectacular because of the way that it looked,” Brickey said. “Word got out, because we do it so rarely, people were out taking pictures of it.” 

After being emptied, the water moves through the river system past Knoxville and into the Ohio River.