A mountain lake draining months later than it typically does is causing ice dams and flooding along the lower Kenai River this weekend.
Flooding became a concern Thursday as water draining from Skilak Glacier Dammed Lake made its way into the lower Kenai River. The lake is behind Skilak Glacier at the head of Skilak Lake, and usually drains every two or so years in late fall once it’s had its fill of meltwater and runoff.
This year it began to drain around Feb. 16.
“These things are finicky,” said Ben Balk, a hydrologist with the National Weather Service in Anchorage. “It delayed and went now.”
The lake’s release typically causes the Kenai River’s water level to rise about 4 feet, which isn’t a problem unless the river is already high from heavy rain or if it’s covered in ice.
“It happened so late that we’ve developed winter ice cover on the lower river,” Balk said. “... (The excess water) started to lift the intact ice and shift it around. As it starts to move downstream it gets jumbled up and dams up on harder intact ice and starts to pinch off the river and causes an ice dam.”
As water rises above the dam, pressure increases on the ice until it finally breaks up and moves downriver at least until it jams up again.
Bill Popp, spokesman with the Kenai Peninsula Borough, said a series of ice jams could form all along the lower river over the weekend as the ice and excess water flush out to Cook Inlet. With the dams could come more localized flooding.
“We’re urging people with property in the area to pay very close attention until we get past this flooding issue,” Popp said. “In the event the water level does start to rise suddenly (property owners should) make plans for how they’re going to evacuate and alternative places to stay.”
The breakup of the larger ice jams at Swiftwater and near Soldotna Creek above the Soldotna bridge could intensify flooding in the Big Eddy area and cause new flooding in other low-lying areas along the rest of the lower Kenai River. Particularly at risk are the Judy Lane and Knight Court areas, and farther downstream at the end of Ciechanski Road.
The National Weather Service reported Saturday evening that the Kenai River water level crested at Kenai Keys during Friday night, which suggests the Skilak Glacier Dammed Lake is done draining. River water levels are expected to drop over the next few days, but a flood watch remains in effect through 5 p.m. Sunday since ice dams still could cause flooding.
The borough, Department of Transportation and Public Facilities, city of Soldotna, Central Emergency Services and Alaska State Troopers are monitoring the situation. The city of Soldotna has 1,000 sandbags available behind City Hall for residents to use. Popp urged residents in low-lying areas along the lower river to remove vehicles, boats and any portable property that may be damaged by floodwater. Anyone with docks or platforms in the river are advised to remove those, as well.
For more information, contact the borough Office of Emergency Management at 262-4910 or online at www.borough.kenai.ak.us/emergency; or the National Weather Service at www.arh.noaa.gov.
Jenny Neyman can be reached at jennifer.neyman@ peninsulaclarion.com.
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