An estimated 290 residences damaged by flooding from lake dammed by Alaska glacier, officials say

JUNEAU, Alaska — About 290 homes in Alaska’s capital were damaged last week Officials say the cause is the flooding of a lake dammed by the Mendenhall Glacier.

In addition to the homes, apartments and condominiums, at least two businesses were damaged, Deputy City Manager Robert Barr said in an email Monday.

The threat of this type of flooding has become an annual concern in parts of Juneau, though the extent of last week’s flooding, which extended further into the Mendenhall Valley, was unprecedented, officials said.

The flooding occurs because a smaller glacier near the Mendenhall Glacier retreated, creating a basin that filled with rainwater and snowmelt each spring and summer. When the water creates enough pressure, it pushes under or around the ice dam created by the Mendenhall Glacier, into Mendenhall Lake and eventually the Mendenhall River.

Since 2011the phenomenon has sporadically flooded streets or homes near the lake and river, but the impact of flooding this year and last year has been significant. The river crested at 15.99 feet (4.9 meters) last Tuesday, the National Weather Service said, breaking the previous record set a year earlier by approximately 0.3 meters.

The state has an assistance program that can help with the cost of repairing damaged homes, with a maximum of $21,250 for an individual or family. Other programs include help to replace essential items such as clothing and temporary housing assistance for residents displaced by the flooding. Barr did not estimate how many people will need such help.