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Army Command Sgt. Maj. Zachary Plummer, senior enlisted advisor of the U.S. Army Corps of Engineers – Pacific Ocean Division, assists a street team in Juneau, Alaska, Aug. 13, 2025, to repair a temporary flood protection barrier along the Mendenhall River, after a tree strike at Diamond Park. © Nahaku McFadden, U.S. Army Corps of Engineers

Mendenhall Glacier’s Seasonal Flood Mitigation Efforts Yield Positive Results


Temporary barriers prove effective during glacial flooding in Alaska

Published on August 19, 2025

Last week, Juneau faced the annual challenge of the Mendenhall Glacier’s lake outburst flood as glacial waters streamed towards the city. Thankfully, extensive preparations made by the U.S. Army Corps of Engineers (USACE) helped mitigate the potential threats to local infrastructure and public safety.

In an effort to protect the community from the risks posed by the flood, the USACE provided temporary flood barriers last winter. According to Army Brig. Gen. Joseph “Clete” Goetz, commanding general of the USACE – Pacific Ocean Division, these barriers played a crucial role in safeguarding property, significantly reducing damage compared to previous years.

“As we continue to evaluate the performance of the barriers, I’m confident they prevented a lot of property damage compared to 2024,” Goetz stated.

During the winter and spring of 2025, an extensive shipment from the USACE National Flood Fight Materiel Center in Illinois brought in approximately 37,800 linear feet of barrier wall, alongside 400 supersacks, 112,000 sandbags, and 25,000 linear feet of polyethylene sheeting. The installation of these materials, completed in two phases, was strategically designed to protect the areas most at risk.

Army Brig. Gen. Joseph C. "Clete" Goetz, commanding general of the U.S. Army Corps of Engineers – Pacific Ocean Division, and Command Sgt. Maj. Zachary Plummer, senior enlisted advisor of the U.S. Army Corps of Engineers – Pacific Ocean Division, discuss street flood mitigation and response efforts with a city employee in Juneau, Alaska, Aug. 13, 2025. Goetz and Plummer traveled from a command center in Hawaii to Juneau to engage with the community and closely monitor the effectiveness of temporary flood protection barriers. © Nahaku McFadden, U.S. Army Corps of Engineers

Army Brig. Gen. Joseph C. “Clete” Goetz, commanding general of the U.S. Army Corps of Engineers – Pacific Ocean Division, and Command Sgt. Maj. Zachary Plummer, senior enlisted advisor of the U.S. Army Corps of Engineers – Pacific Ocean Division, discuss street flood mitigation and response efforts with a city employee in Juneau, Alaska, Aug. 13, 2025. Goetz and Plummer traveled from a command center in Hawaii to Juneau to engage with the community and closely monitor the effectiveness of temporary flood protection barriers. © Nahaku McFadden, U.S. Army Corps of Engineers

Phase one, covering around 2.5 miles between Marion Drive and Rivercourt Way, was finalized in the spring. Phase two will incorporate lessons learned from the current flood event to ensure comprehensive protection throughout the rest of the area.

The USACE, recognized as the leading federal agency for flood management, provided valuable technical assistance to the local community during this process. The decision-making involved careful analysis of prior flood data including high-water marks and local topography. The barriers were built up to the elevation of the recorded high-water marks, with an additional 4 feet for added security, leading to some barriers reaching 8 feet high.

Originating from the U.S. Army Corps of Engineers National Flood Fight Materiel Center in Ill., about 37,800 linear feet of barrier wall, 400 supersacks, 112,000 sandbags and 25,000 linear feet of polyethylene sheeting were shipped to Juneau, Alaska, during the winter and spring of 2025 and strategically installed along the Mendenhall River by the city in two phases. As the lead federal agency for floods, the U.S. Army Corps of Engineers provided technical assistance and advisement to the community throughout the process. © U.S. Army Corps of Engineers National Flood Fight Materiel Center

Originating from the U.S. Army Corps of Engineers National Flood Fight Materiel Center in Ill., about 37,800 linear feet of barrier wall, 400 supersacks, 112,000 sandbags and 25,000 linear feet of polyethylene sheeting were shipped to Juneau, Alaska, during the winter and spring of 2025 and strategically installed along the Mendenhall River by the city in two phases. As the lead federal agency for floods, the U.S. Army Corps of Engineers provided technical assistance and advisement to the community throughout the process. © U.S. Army Corps of Engineers National Flood Fight Materiel Center

“The successful deployment of these temporary flood protection barriers is reflective of a total team effort,” said Army Col. Jeffrey Palazzini, commander of the USACE – Alaska District. “The preparation and partnership were on full display during the flood event of the past 24-48 hours.”

As of August 14, the barriers have proven effective against what has become a record flood season for the Mendenhall River Valley, with water levels peaking at alarming heights. The U.S. Geological Survey recorded a high of 16.6 feet this week, surpassing the previous years’ peaks of 14.97 feet in 2023 and 15.99 feet in 2024.

USACE leadership actively monitored the situation on-site and engaged with local stakeholders, emphasizing the importance of ongoing short-term flood mitigation efforts in Juneau. While a long-term solution will require extensive planning and time, immediate safety remains a top priority for the organization moving forward.

Environmental Reporter