Introduction to the Flooding Incident
New sandbag-style barriers installed along a river in Alaska’s capital city held back record levels of flooding and prevented widespread damage after an ice dam at the nearby Mendenhall Glacier released a massive amount of rainwater and snowmelt downstream, officials said Wednesday.
Water pooled on several streets and in some yards in Juneau after the Mendenhall River crested earlier in the day, and high water was expected to persist for hours. But many residents in the flood zone evacuated ahead of peak water levels, and there were no damage reports similar to the last two years, when flooding was rampant and some homes washed away.
The Mendenhall Glacier and Its Impact
The Mendenhall Glacier is about 12 miles (19 kilometers) from Juneau, home to 30,000 people in southeast Alaska, and is a popular tourist attraction due to its proximity and easy access on walking trails. Homes on the city’s outskirts are within miles of Mendenhall Lake, which sits below the glacier, and many front the Mendenhall River, into which the glacial outburst flowed.
Juneau, which is accessible only by boat and plane, is 570 miles (917 kilometers) southeast of Anchorage, Alaska’s largest city. The flooding won’t impact Friday’s summit in Anchorage between President Donald Trump and Russian President Vladimir Putin.
Basin Flooding: A Yearly Concern
Flooding from the basin has become an annual concern since 2011 and has gotten worse in recent years. It happens because a smaller glacier near Mendenhall Glacier retreated — a casualty of the warming climate — and left a basin that fills with rainwater and snowmelt each spring and summer, dammed by the glacier.
When the water builds up enough pressure, it forces its way under or around the ice dam, enters Mendenhall Lake, and flows down the Mendenhall River.
The city saw successive years of record flooding in 2023 and 2024, with flooding extending farther into the Mendenhall Valley.
Last year, nearly 300 residences were damaged.
The Barriers: A Temporary Solution
City officials responded to concerns from property owners this year by working with state, federal and tribal entities to install a temporary levee along roughly 2.5 miles (4 kilometers) of riverbank in an attempt to guard against widespread flooding. The 10,000 “Hesco” barriers are essentially giant, reinforced sandbags intended to protect more than 460 properties, said emergency manager Ryan O’Shaughnessy.
The barriers "really have protected our community,” Juneau City Manager Katie Koester told a news conference. “If it weren’t for them, we would have hundreds and hundreds of flooded homes.”
A large outburst can release some 15 billion gallons of water, according to the University of Alaska Southeast and Alaska Climate Adaptation Science Center. That’s the equivalent of nearly 23,000 Olympic-size swimming pools. During last year’s flood, the flow rate in the rushing Mendenhall River was about half that of Niagara Falls, the researchers say.
Challenges and Future Plans
But the measure was not without critics. Two homeowners have sued, complaining that the government was taking their property to erect the barriers without compensating them.
On Tuesday and Wednesday, some water seeped into yards through drains that had been installed under the barriers. In other spots, trees floating down the river struck and damaged the barriers, officials said.
The U.S. Army Corps of Engineers is at the start of what’s expected to be a yearslong process of studying conditions in the region and examining options for a more permanent solution, such as a levee. The timeline has angered some residents, who say it’s unreasonable.
Outburst floods are expected to continue as long as the Mendenhall Glacier acts as an ice dam to seal off the basin, which could span another 25 to 60 years, according to the university and science center researchers.
Conclusion
In conclusion, the new river barriers in Juneau, Alaska, have successfully prevented severe damage from a glacial outburst, protecting hundreds of homes and properties. While the barriers are a temporary solution, they have proven effective in mitigating the impact of flooding in the area. Further studies and plans are underway to find a more permanent solution to the flooding problem, which is expected to continue for decades to come.
FAQs
- Q: What caused the flooding in Juneau, Alaska?
A: The flooding was caused by a glacial outburst from the Mendenhall Glacier, which released a massive amount of rainwater and snowmelt downstream. - Q: What measures were taken to prevent flooding?
A: The city installed temporary levees along the riverbank, using 10,000 “Hesco” barriers to protect over 460 properties. - Q: How long is the flooding expected to continue?
A: Outburst floods are expected to continue for another 25 to 60 years, as long as the Mendenhall Glacier acts as an ice dam to seal off the basin. - Q: What is being done to find a more permanent solution?
A: The U.S. Army Corps of Engineers is studying conditions in the region and examining options for a more permanent solution, such as a levee.
