Floodwaters in Juneau, Alaska, have receded after a record flood event stemming from a glacial outburst threatened the city this past Wednesday.
An ice dam from the Mendenhall Glacier released a significant amount of water, causing water levels in the Mendenhall River to rise dangerously high.
City Manager Katie Koester expressed relief at the effectiveness of the Hesko barriers that were put in place, stating, “We can all breathe a sigh of relief. For the most part we had very minimal flooding and avoided a really catastrophic event.”
The National Weather Service reported that the flooding peaked around 7:15 a.m. local time, with levels reaching an unprecedented 16.65 feet in the river.
This surpassed the previous record of 15.99 feet set just last year.
Koester highlighted that without intervention, nearly 1,000 structures, primarily residences, could have faced flooding for the second consecutive year, warning of the damage cold, icy waters could inflict.
The Mendenhall Glacier, located approximately 12 miles from downtown Juneau, is a major attraction for tourists and locals alike.
Homes near the glacier and along the Mendenhall River are at risk, particularly when outburst floods occur from the glacial basin.
On Tuesday, anticipating the danger, city officials urged residents in the flood-prone areas to evacuate immediately.
Authorities allowed evacuees back to their homes only in the afternoon of Wednesday.
City crews are now assessing flooding damage, advising residents against driving through any standing water due to potential hazards.
Driving could generate waves that further damage nearby structures, according to city guidelines.
Michael Downs, a U.S. Forest Service ranger, shared updates at a news conference on Wednesday morning, stating that parts of the recreation area near the glacier remain underwater.
Several trails in the surrounding national forest are also closed until further notice, with full assessments expected to take five to six days.
The visitor’s center within the recreational area, however, is set to reopen Thursday.
Due to the flooding, public schools in Juneau will delay their return for the upcoming academic year, resuming classes on Friday instead of Thursday, as confirmed by school district superintendent Frank Hauser.
Flooding from the glacial basin has posed a recurring threat since 2011, leading to significant damages to homes in recent years.
In an effort to mitigate this year’s risks, temporary barriers were installed to protect hundreds of homes in the inundation zone.
The flooding is exacerbated by the retreat of a smaller glacier near Mendenhall, creating a basin known as Suicide Basin, which fills with rainwater and snowmelt each spring and summer.
As pressure in the basin builds, water forces its way beneath or around the ice dam formed by the Mendenhall Glacier, eventually flowing into Mendenhall Lake and down the river.
The National Weather Service reported that the water level was rising by as much as four feet daily before the outburst began.
Juneau has faced successive years of record flooding, with this year’s levels anticipated to rise as high as 16.8 feet.
Last year’s flood resulted in nearly 300 residences suffering damage.
Visual reports from previous flood events captured the dramatic impact on the landscape, with trees falling and even homes collapsing into the river.
Estimates suggest a large outburst flood can release as much as 15 billion gallons of water, equivalent to nearly 23,000 Olympic-sized swimming pools.
During last year’s flooding, flows in the Mendenhall River reached rates comparable to half that of Niagara Falls.
To mitigate future flooding risks, city officials collaborated with state, federal, and tribal agencies to install a 2.5-mile temporary levee along the riverbank.
This effort utilized 10,000 Hesco barriers, designed to protect over 460 properties in the event of an 18-foot flood.
The U.S. Army Corps of Engineers has initiated a long-term study of the region’s conditions and is exploring options for a more permanent solution, such as a levee system.
However, the timeline for these solutions has faced criticism from local residents who argue that it is too lengthy.
Experts predict that outburst floods will continue as long as the Mendenhall Glacier acts as an ice dam to the basin.
This scenario could persist for another 25 to 60 years, leaving the community to cope with the ongoing risks associated with climate change impacts on glacial stability.
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