
CBJ- As the snow melts, City and Borough of Juneau (CBJ) crews and contractors are now moving quickly to repair, raise and reconstruct the Phase 1 HESCO barrier project ahead of a 2026 glacial lake outburst flood (GLOF) event.
CBJ’s Engineering and Public Works department has spent months documenting damage, analyzing impacts and vulnerabilities, and utilizing the latest available hydrologic and hydraulic modeling to develop plans for the reconstruction of existing Phase 1 HESCO barriers. The CBJ Assembly has identified GLOF response, mitigation & preparedness as a top priority. The goal of this ongoing work, done in coordination with the U.S. Army Corps of Engineers (USACE), is to ensure that these flood fighting projects provide as much protection as practicable until a longer-term solution is in place.
The project includes additional bank armoring and raising HESCO barriers to protect Mendenhall Valley residents from future floods up to 90,000 cubic feet per second or approximately a 20-foot lake stage flood. A map showing planned reinforcements and raising of Phase 1 is available at juneau.org.
“The HESCO barriers proved their value in 2025, but we had some close calls, we’ve learned a lot, and we aren’t taking any chances in 2026,” explains CBJ City Manager, Katie Koester. “By doing this major reconstruction work in 2026, we can have confidence in the protection of the HESCO barriers against larger flood events, with less future disruption to residents and lower annual maintenance costs to the community.”
The 90,000 CFS flow rate represents a 50-year GLOF event and is the number the USACE is using in their evaluation of mid-term flood fighting solutions for Juneau. Constructing to the 50-year event now, instead of annual incremental increases, will reduce future annual costs and minimize annual disruption to property owners. The “50-year event” is a probability-based number that represents the comparatively higher likelihood that a flood of 90,000 CFS may occur. Based on projections, it is possible that the Mendenhall River could experience a 90,000 CFS (20 ft) event within the operational life of the HESCO barriers.
The 2026 Phase 1 reconstruction and fortification will not impact the Local Improvement District (LID) assessments for the original Phase 1 construction. This year’s project is a separate scope that is fully funded by CBJ funding and Alaska Department of Conservation State Revolving Loan funds. CBJ and agency partners are also actively seeking grant funding to support this project.
CBJ project managers have and will continue to coordinate directly with property owners and impacted residents along the Phase 1 and Phase 2 project areas. More information about flood fighting, flood emergency preparedness and the pursuit of an enduring solution is available at bit.ly/CBJGLOF.
In addition to barrier reinforcement and fortification, CBJ is making improvements to drainage and stormwater management in the area. CBJ is coordinating with USACE to acquire over 40 industrial-grade pumps to deploy to strategic staging locations based on anticipated water intrusion risks. These pumps will be deployed to serve the community as a whole rather than individual properties. Importantly, they can operate for up to 24 hours do not require refueling during an event, allowing both staff and residents to safely evacuate inundation areas.
Phase 2 HESCO Barriers
USACE – Alaska District, in partnership with CBJ, began the first phases of the Phase 2 HESCO barrier project installation along the Mendenhall River last month. USACE contractor Sealaska Constructors is leading the work. The Advance Measures scope includes riverbank armoring and installation of temporary (HESCO) flood barriers to construct a fortified, complete temporary flood barrier along the unprotected, populated riverbank areas of the Mendenhall River – referred to as Phase 2 – prior to July 15, 2026. For questions about the Phase 2 HESCO Barrier Project, please contact public.affairs3@usace.army.mil.
Safety
CBJ and USACE are on a tight timeline to complete construction before the next GLOF. We ask that the public avoid the construction area for your safety and the safety of workers, residents and property owners, and to allow for efficient and expedient operations.









