A flood advisory is in effect for the Kenai Peninsula until midweek.
The Kenai River at Cooper Landing hit flood stage, 13 feet, Monday morning National Weather Service meteorologist Eric Halloway said, and by 1 p.m. the river was at 13.3 feet.
The increase in water is due to the Snow Glacier dammed lake releasing and emptying water into Snow River. The river, which has risen more than 6 feet, flows into Kenai Lake. The heavy weekend rain throughout the Peninsula extended the flood advisory to 3 p.m. Wednesday.
The weather service expects the Lower Kenai River to rise steadily and potentially reach minor flood stage later this week.
“It’s going to take quite a while for this water to make it through the entire Kenai River,” Halloway said.
Scott Walden, Kenai Peninsula Borough emergency management director, said residents in affected areas should move items back or secure things that could be washed away in the rising river.
Two to three inches of rain is expected Tuesday with an additional two to three inches on Wednesday and rain will likely continue into Thursday and Friday, Halloway said.
The additional rainfall could increase water levels late in the week, according to the weather service.
“It’s going to be really wet,” Halloway said.
The glacial release on Snow River usually happens every two years in the fall. Water builds up behind the glacier, and then the water’s pressure behind the glacial dam pushes the glacier up and re-establishes waterways under the ice. The rise takes two to three days, Halloway said, and the water increases its flow rate from about 2,800 cubic feet per second to about 18,500 cubic feet per second during the release.
The water behind the glacier usually completes releasing in six to seven days. He said the weather service thinks the release began early Oct. 9. However, the weather service is unable to determine the volume of water behind the glacier because the Civil Air Patrol, which assists the weather service in monitoring glacial dammed lakes, most recently flew to the glacier nearly a month ago.
“We have no regulation on what is released behind the glacier, so it’s basically an uncontrolled spill,” Halloway said.
The weather service is able to base the timing and regularity of the phenomena on previous releases, he said, but the heavy rain and not knowing exactly how much water is behind the glacier complicates predicting the effects of the glacier release.
The changing climate could additionally complicate meteorologist’s abilities to predict glacial releases and their effects.
“With climate change, glaciers are receding,” Halloway said. “All of these glacial dammed lakes could change in the future as far as timing (and) how often they occur.”
He said there are “quite a few” glacier dammed lakes on the Peninsula, but Snow River and Skilak Lake are the only two that cause Kenai River flooding concerns.
Walden said the “fairly regular” event still carries concerns of people’s belongings being washed into the river and roads being affected.
“We want to make sure people are preparing their homes,” he said.
Kaylee Osowski can be reached at firstname.lastname@example.org.