Kenai River reaches flood crest, begins dropping

After reaching 15.06 feet, nearly a foot above the minimum for flood-stage designation, the water level had declined to 14.15 feet -- just below flood stage -- Tuesday afternoon and was expected to continue dropping. The National Weather Service officials said several garages -- but no dwellings -- had been flooded in the Kenai Keys and Big Eddy areas.

An ice-dammed body of water above Skilak Glacier in the headwaters of Skilak Lake released 10 days ago for the first time since January 2007, prompting the high water. National Weather Service hydrologist James Montesi estimated 120,000 acre feet of water was released into the Kenai River.

"Usually, it's not a problem," Montesi said. "Usually it releases later in the fall when the Kenai's water levels are lower."

This time, recent rainfall had swollen the Kenai, and the release boosted a water-level gauge below Skilak Lake 2 1/2 feet, "which is a lot," Montesi said.

At the time of the release, forecasters were monitoring a storm that brought some 8 inches of rain to the Cordova area.

"We saw it come, but it just slid east of the Kenai Peninsula," Montesi said. "We were thankful -- it could have been a lot worse. It could have been as bad as '95."

In September of that year, heavy rain saw the Kenai River crest 3 1/2 feet above the flood stage while the heavy rainfall throughout Southcentral brought a federal disaster declaration. A month later, the glacial lake above Skilak Lake broke, too, and the river shot up several feet again.

The Skilak Glacier lake fills with rainwater and snowmelt, and drains suddenly every two to five years, the National Weather Service said.

The lake drains through the ice into Skilak River and Skilak Lake, which spreads the water and reduces the rise of the Kenai River at the lake's outlet.

Hydrologists anticipate a glacially dammed lake above Snow Glacier that hasn't released since November 2007 could give way later this year.

"It's similar," Montesi said. The Snow Glacier lake would dump into Kenai Lake, which flows into the Kenai River before reaching Skilak Lake.

"How bad that is will be depend on the Kenai (River) levels at the time it releases. Glacier melt will have stopped by then.

"The mechanism for the trigger isn't totally understood."

Similar glacial lakes that periodically release are near Knik Glacier, on the Tazlina River and near McCarthy, he said.

"They're identified so there's no surprises," Montesi said. "But they're a surprise exactly when they go. We have a range of time but can't forecast it to the day."

Reporter Mike Campbell can be reached at mcampbell@adn.com or 257-4329.