The rapid release of water from a glacier-dammed lake has prompted a flood advisory for Kenai Lake and the Kenai River near Cooper Landing, according to the National Weather Service.
Water levels are expected to rise significantly this week at Kenai Lake and the Kenai River from Cooper Landing to Skilak Lake.
“The Snow glacier dammed lake is releasing at this time,” the weather service said in its advisory. “Water levels on the Snow River are steadily rising and are reflective of previous outburst events.”
Water levels may continue to rise through early next week, and according to the weather service, the “Kenai River below Skilak Lake will likely see a more moderate increase to bankfull conditions by early next week."
“There is considerable uncertainty of water volumes released and drain rates during glacial dammed lake outbursts,” the weather service said, urging people to check the Alaska-Pacific River Forecast Center website for updates.
The flood advisory remains in effect until 12:15 p.m. Friday. It comes at a time when the Kenai Peninsula is also experiencing degraded air quality due to smoke from multiple wildfires, the largest of which is burning over 140,000 acres between Cooper Landing and Sterling.
According to the Alaska-Pacific River Forecast Center, the Snow Glacier Dammed Lake, which is "located in the headwaters of the Snow River east of Moose Pass and is blocked by the Snow Glacier ... releases every two to three years in the fall.”
The last release, according to the center, was in September 2017, when 105,000 acre-feet of water was released. That event caused minor flooding in Cooper Landing, left 2 to 3 feet of water over the road leading to the Primrose Campground and sent water “approaching the foundations of houses along Primrose Road,” the center says on its website.
“Glacier dammed lakes are formed when a glacier blocks the flow of water out of a tributary valley," according to the center. "Throughout the seasons rainfall, rainfall runoff, snowfall, snow melt and glacier melt all accumulate in the lake. At a semi-regular interval, which differs for each lake, the lake begins a self-dumping process.”