The storage and release of water from a large glacier-dammed lake; Russell Lake near Yakutat, Alaska, 1986

In May 1986, the entrance to Russell Fiord, Alaska, was blocked by the advancing Hubbard Glacier, forming a 34-mile long ice-dammed lake. Runoff to the lake, mainly runoff from melting snow and glacier ice, filled the lake to an elevation of 83 feet above sea level by October 8, when the ice dam failed. The lake level rose at an average rate of 0.6 ft/day, and average daily inflow to the lake was calculated to be 16,500 cu ft/sec. After failure of the ice dam, the water level fell to the former high tide level of Russell Fiord within 24 hours. Average discharge through the breach in the ice dam during a 4-hr period of maximum water level decline is estimated to have been 3.8 million cu ft/sec. The formation and breakout of the lake is expected to be repeated as the Hubbard Glacier continues to advance, though the timing of the phenomenon cannot be predicted with certainty. (USGS)