Lake George Breakout

Whatever happened to the Lake George Breakout? The resulting flooding of the Knik River near Palmer, Alaska, used to be a fairly regular, if not welcome, event. But, fourteen years now have passed since the last breakout in June 1966.

This famous phenomenon results from glacier and snow meltwater being trapped in the valley of Lake George by the Knik Glacier pressing its face against Mount Palmer. After the glacier closes off the valley, spring waters can enlarge Lake George until it covers as much as 25 square miles (65 sq. km) and is up to 160 feet (50 meters) deeper than minimum level.

The rising lake water eats away at the face of the glacier where it touches Mount Palmer until a channel is cut through. Once it starts to flow, the water cuts the channel into a gorge 5 miles long, 100 to 400 feet wide and 300 feet deep. Through the gorge the water flow can be as great as 150 million gallons per minute. That is comparable to the flow in the Columbia River at flood stage.

Flooding from the Lake George Breakout is not known to have occurred until it wiped out three Indian villages on the Knik River just before 1900, although people living in the region said it emptied itself every 15 to 20 years before that. Irregular flooding from the Breakout occurred until 1914. Thereafter until 1966, during almost every June or July, Lake George floodwaters threatened structures on the Knik River flood plain.

Since 1966, the gorge has remained open and therefore Lake George has not formed. There seems to be no question about whether or not the Lake George Breakout will again occur; it is just a question of when.