KENAI - Scientists are trying to figure out what caused Torpedo Lake to dump 10 percent of its water - or about 65 million gallons - into the Kenai River.
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"It's a very impressive geological event," said Robert Ruffner, executive director of the Kenai Watershed Forum. "(And) it's certainly somewhat of a mystery still as to what happened."
The lake is about four miles downstream of Skilak Lake, and drains into the river through a channel. As it leaves the lake, the approximately 200-yard channel drops into a ravine.
Subdivision resident Dave Bunnell said one could step over the channel until Oct. 16, when a 2- to 3-foot-tall wall of peat holding the 60-acre Torpedo Lake back gave way.
"It had to have drained in a pretty catastrophic failure, to widen the channel and deepen it as much as it did," Ruffner said. "It shot a large volume of water through that old ravine and cleared it out. It took birch trees and spruce trees and a tremendous amount of peat with it."
Ruffner estimated the event dropped the lake's surface by 31/2 feet.
However, it's not known what caused the peak to give way.
"We went out there to see if it was associated with ATV trails and we didn't find any evidence that it was anything other than natural," Ruffner said.
He said a Kenai Keys subdivision resident said the ravine had been gradually eroding its way back toward the lake before the peat gave way.
The stream once trickled down from the lake. Now, a 5- to 6-foot waterfall falls into the ravine.
Ruffner said trying to figure out what happened in an erosion event is challenging because evidence has been washed away.
"It's a little bit of a detective story to try to go back and piece together (what happened) without having all the evidence available," he said. "When the lake blew, all of what was there, it took with it."