Flood advisory issued in Primrose, Cooper Landing following glacial dam release
The National Weather Service has issued a flood advisory for the areas around the Snow River, Kenai Lake and the Kenai River to Skilak Lake on the central Kenai Peninsula.
This will primarily impact the Primrose area, north of Seward, and Cooper Landing.
The advisory went into effect Saturday, Sept. 3, and is scheduled to be in place until Thursday, Sept. 8 at 2:30 p.m.
The National Weather Service alert warns of water flows over the Primrose Campground on the southeast shore of Kenai Lake that will make the area impassable to small vehicles. And flooding could occur at residences on the Sterling Highway between Mileposts 48 and 50 in Cooper Landing, at the Cooper Landing boat launch and at the Quartz Creek boat ramp and campsites.
Marian Baker, senior service hydrologist at the National Weather Service Anchorage Forecast Office, said the flooding is a result of a glacial dam release, which occurred at Snow Glacier, about 25 miles northeast of Seward.
“All that is, is the glacier melts, and it melts to a certain point and then it reaches a point where it releases off into the Snow River, and that is what the advisory is about," Baker said.
The Snow Glacier Dammed Lake is at the headwaters of the Snow River, and blocked by the Snow Glacier. However, when the glacier melts a certain amount, water is released from the lake before flowing down the Snow River, into Kenai Lake, through the upper Kenai River and into Skilak Lake.
“By the time it reaches Skilak Lake, the landscape gets much more flat and it has a lot more capacity to hold the flows in the basin itself," she said.
The threat, Baker said, is primarily to low-lying, flat and swampy areas, which will receive more water than normal.
The Snow Glacier Dammed Lake releases roughly every two years. The last time it broke was in October 2020. Baker explains that this is because in order for the glacier to melt enough to release, it needs about two years of melting time. This phenomenon is known by the Icelandic word jökulhlaups, which means a flood that bursts suddenly from a glacier.
Baker says the river’s heights are falling at a fast rate, such that the National Weather Service may consider canceling the flood advisory early. For now, she says, this situation poses a low risk to life and property and is more of a nuisance. She recommends people stay out of flooded areas.
Baker also warns that motorists should not drive through flooded roadways, and any property owners along waterways should be careful about storing items too close to the water.