Melting of Water from the Ice Dam of Mendenhall in Alaska

• The ice dam in Alaska has started to release water, posing a threat of flooding.
• A temporary dam has been established to protect against flooding.
• Record flood levels began in 2023 and 2024.

The ice dam, formed by melting water and the accumulation of snow under the Mendenhall Glacier in Alaska, has started to release water. Officials on August 12, 2025, urged residents in some areas of Juneau to evacuate due to the potential record surge of floodwaters.

In recent days, authorities have warned people in the flooded zone about the need to be prepared for evacuation. In the afternoon, officials confirmed that water began to leak from the ice dam and the flow is expected to continue from late afternoon to mid-evening.

This flooding has become a recurring problem that in recent years has led to the destruction of buildings and flooding of residential areas. Government agencies this year established a temporary dam to prevent large-scale flooding.

The glacial glacier, which is also an important tourist attraction in southeastern Alaska, plays a role in the dam for the Suice basin, which is filled with meltwater and glacial runoff. When the water level in the basin becomes sufficient, water breaks through the ice dam, entering Mendenhall Lake and further into the Mendenhall River.

With the threat of so-called "ice floods" affecting Juneau since 2011. In some years, limited flooding of streets and properties around the lake and river has been observed. However, 2023 and 2024 have become record years for floods, with water levels in the river reaching 15.99 feet (4.9 meters), surpassing the previous record.

Last year, nearly 300 residential buildings were flooded. A significant flood could release nearly 15 billion gallons of water, equivalent to approximately 23,000 Olympic swimming pools. During last year's flooding, the flow in the Mendenhall River was approximately twice as low as in the Niagaras Falls.

Local officials reacted to the flooding by working with state, federal, and local organizations to establish a temporary dam extending approximately 2.5 miles along the riverbank to protect over 460 properties. The establishment of nearly 10,000 four-foot (1.2 meter) barriers aims to protect against similar flooding levels compared to last year's.

The U.S. Army Corps of Engineers began assessing conditions in the region and exploring options for more permanent solutions. It is expected that ice floods will continue as long as the Mendenhall Glacier remains, which could last another 25-60 years.

Tags: USA/Weather