Hesco Barrier Phase 1 + 1A

Latest Updates

3/11/2026: CBJ, with technical assistance from USACE, is finalizing plans to raise, repair and reinforce the existing Phase 1 HESCO barriers before the next GLOF event. Implementation and construction will begin in mid-to-late March 2026. Impacted property owners and residents have been notified.

10/30/2025: The USACE accepted CBJ’s request for USACE Public Law 84-99 Advance Measures Assistance to protect against the increasing future glacial lake outburst floods. USACE will provide installation for a Phase 2 of temporary flood barriers and technical assistance for Phase 1 repairs and reinforcement.

7/30/2025: The Phase 1 and 1A HESCO barrier installations are complete. CBJ is confident that the barriers will provide protection as designed, however, the City plans to issue an evacuation alert for the prospective inundation area during a 2025 Basin release and strongly encourages residents in the area to evacuate until the water recedes.

6/2/2025: The CBJ Assembly decided not to move forward with the proposed Phase 1B HESCO barrier installation until the appropriate funding discussions, community conversations and bank armoring could be completed. See the Assembly COW meeting recording and materials here.

See “Timeline & Status” below for additional updates.

Project Background

The Mendenhall River Valley in Juneau, Alaska is under imminent threat of unusual flooding from what scientific experts expect will be recurring and likely record-breaking glacier lake outburst flood (GLOF) events. The impact and inundation area of these events have increased each of the last three years; a pattern that puts hundreds of homes and thousands of vulnerable residents, as well as critical infrastructure, public facilities, and community and medical services at risk.

CBJ is working tirelessly with Federal, Tribal, State and local partners to gather the additional information and resources needed to identify and implement a long-term solution. However, a long-term solution will take years before it can be implemented due to the unusual source and nature of the flooding and the complex hydraulics and engineering required.

Therefore, emergency mitigation and immediate flood resilience action was needed to provide practical protection of the most vulnerable in our community before the 2025 GLOF season, and until a long-term solution is in place.

With extensive consultation and involvement from United States Army Corps of Engineers (USACE) flood fighting experts, CBJ installed USACE provided HESCO barriers as a near-term solution to mitigate potential widespread damage from future releases. Based upon factors such as the high-water marks obtained after the 2024 and 2025 GLOF events and the resources available to implement a solution before July 2025, an approximately 2 mile stretch of riverbank was identified which would provide the most protection to the highest number of flood-vulnerable residents and homeowners. This is considered Phase 1 of CBJ’s formal flood mitigation efforts.

After the completion of Phase 1, CBJ moved forward with Phase 1A of the project which included the installation of an additional 3,000ft of HESCO barriers south of Phase 1. Phase 1A was constructed on CBJ property and protects community assets such as two schools, a pool, library, and field house.  

CBJ, with technical assistance from the USACE, is now moving forward with repairs, raising and reinforcement of the Phase 1 and 1A HESCO barrier after learning from the 2025 GLOF. This significant repair and reconstruction work will begin in March 2026 for completion in July 2026. Initial funding is provided by an Assembly transfer of funds from the Capital Civic Center project.

The USACE is providing Advance Measures flood fighting support with riverbank armoring and installation of temporary (HESCO) flood barriers along the remaining unprotected, populated riverbank areas of the Mendenhall River – referred to as Phase 2 – to construct a fortified, complete temporary flood barrier prior to July 15, 2026.

This interim flood fighting solution is intended to provide practicable protect against GLOFs that are up to 18ft high and was guided by the work of a comprehensive hydrological and hydraulic analysis and mapping. The inundation modeling shows that Phase 1 did not cause negative upstream or downstream consequences.  More information on the inundation modeling and interactive mapping tools are available at JuneauFlood.com.

Project Summary

HESCO Barrier Phase 1 includes additional bank armoring, site preparation (obstruction relocation/removal, soil improvement), barrier placement, drainage installation, and barrier filling along the two-mile stretch of riverbank that would provide the most protection to the highest number of flood-vulnerable residents and properties.  Additional project and associated information can be found in the Relevant Resources tab.

Phase 1 was funded through a Local Improvement District (LID) process.  Due to the urgent nature of the HESCO barrier project, Phase 1 was field constructed using best professional judgment and technical guidance from the U.S. Army Corps of Engineers while inundation modeling was in development.  The final inundation modeling shows that Phase 1 did not cause negative upstream or downstream consequences.

Based on the flood inundation maps released in May of 2025, the CBJ Assembly approved extending the HESCO barrier installation to Phase 1A, which included the installation of an additional 3,000ft of HESCO barriers south of Phase 1 as described in this memo (View the Special Assembly COW meeting materials and meeting recording.). Phase 1A was constructed on CBJ property and protects community assets such as two schools, a pool, library, and field house.  Work on Phase 1A began on May 13, 2025 and was completed in early June.

Future Phases

On May 19, 2025, the Assembly directed staff to develop a local improvement district (LID) that includes the cost of the installation and associated armoring for Phase 1B, which extends from the end of Phase 1A to Brotherhood Bridge, with a goal of construction before the 2026 GLOF. Based on preliminary estimates, Phase 1B could be accomplished for $2.2M. 

Phase 2 of the HESCO Barrier project would protect the remainder of the homes and developed properties along the Mendenhall River that would be impacted by flooding greater than 16’ flood stage.  The solutions and costs for Phase 2 are potentially both more varied and more costly. Based on preliminary estimates, CBJ anticipates that the future cost of a Phase 2 HESCO Barrier project could exceed $17M. 

Estimated Project Timeline

  • January 2025: 95% HESCO alignment published.
  • Jan/Feb 2025: CBJ to refine alignment with riverfront property owners.
  • Feb/Mar 2025: CBJ/Property owner MOU negotiation.
  • Mar/Jul 2025: Bank armoring and barrier installation.

Project Status Updates:

7/30/2025: The Phase 1 and 1A HESCO barrier installations are complete. CBJ is confident that the barriers will provide protection as designed, however, the City plans to issue an evacuation alert for the prospective inundation area during a 2025 Basin release and strongly encourages residents in the area to evacuate until the water recedes.

6/2/2025: The CBJ Assembly decided not to move forward with the proposed Phase 1B HESCO barrier installation until the appropriate funding discussions, community conversations and bank armoring could be completed. See the Assembly COW meeting recording and materials here.

5/12/2025: The CBJ Assembly approved extending the HESCO barrier installation to Phase 1A, as described in this memo. View the Special Assembly COW meeting materials and meeting recording. Work to begin on May 13, 2025.

05/08/2025: New Flood Inundation Maps are now available here. The maps demonstrate the effectiveness of the HESCO barriers for floods similar to those experienced in 2024.

04/30/2025: During the first three weeks of April, technical consultants from USACE inspected and approved the work performed thus far for compliance with USACE and manufacturer standards . The project reached approximately 70% completion as of April 28.

04/09/2025: CBJ contractors have installed over 2500 linear feet of HESCO barriers along the project route. Bank armoring and the installation of new one-way storm drain check valves continues. We greatly appreciate the continued cooperation and communication with riverfront homeowners and the wider community.

03/24/2025: CBJ contractors began installing the first HESCO barriers the project route, beginning along Killewich Drive.

03/21/2025: CBJ encourages riverfront property owners in the HESCO barrier project area to research their property’s drainage system to identify the inlet and outlet to all drainpipes. CBJ released an FAQ document with guidance on this topic.

03/19/2025: Contractors began site and access preparation for the HESCO barriers. Please watch for construction equipment and personnel, obey construction traffic control signage.

Four contractors have been selected to perform construction and installation work for Phase 1: Admiralty Construction, Coogan Construction Company, G. R. Cheeseman Construction, North40 Construction Corporation.

Please watch for construction equipment and personnel, obey construction traffic control signage, and stay alert while in and around the work areas to ensure the safety of yourself and others.  We appreciate your understanding and patience.

03/03/2025: The LID ordinance (link) is now in effect. CBJ project managers and contractors are conducting site visits at homes where barriers will be installed. HESCO barriers and flood fighting materials are in transit to Juneau. The Assembly approved the “Notice to Property Owners and MOU” (View Memo and meeting materials).

02/03/2025: The proposed LID passed by at the February 3, 2025 Assembly meeting. View the public hearing meeting materials and objections submitted here.

01/27/2025: CBJ staff presented an a status update and overview of the variety of grants, funding partnerships, funding agencies, and activities being pursued (as of 1/22/25) to support the Phase 1 HESCO and other efforts to meet Juneau’s flood preparedness, response, and/or mitigation needs at the January 27 Assembly PWFC meeting. (Link to memo, funding overview)

01/03/2025: CBJ hosted a public meeting on Friday, January 3 to discuss the proposed LID and Phase 1 of the HESCO barrier flood mitigation project which included a presentation (Link to presentation). The recording of this meeting can be found on CBJ’s YouTube page (Link to recording)

12/16/2024: The CBJ Assembly amended and approved for distribution a proposed Local Improvement District (LID) which would distribute the anticipated $7.8 million project cost across the 466 property owners in the project area that would be impacted by a 16-foot flood event (40% of cost), with the rest borne by CBJ (60% of cost).

11/14/2024: CBJ and the U.S. Army Corps of Engineers hosted public events on November 12 and 14 to share knowledge and answer questions about flood preparations for homeowners. An electronic copy of the presentation is available HERE and a recording of the presentation and Q&A is available at https://youtu.be/Ohy0oD4uAU0 .

HESCO Barrier Project LID

A Local Improvement District, or LID, is a mechanism in CBJ code for a benefited property to pay for an infrastructure improvement (in this case, the installation of the infrastructure to protect properties and homes from flooding). LIDs are governed under CBJ Code.  The Mendenhall GLOF LID has been proposed by the Assembly in Ordinance 2024-40(am).  A copy of the Mendenhall GLOF LID frequently asked questions can be found here.

HESCO Barrier FAQs

Please Note: The Phase 1 and 1A HESCO barrier installations are now complete. CBJ is confident that the barriers will provide protection as designed, however, the City plans to issue an evacuation alert for the prospective inundation area during a 2025 Basin release and strongly encourages residents in the area to evacuate until the water recedes.

Riverfront Property Memorandum of Understanding (MOU)

At the March 3. 2025 Assembly meeting, the Assembly and the public were provided with a copy of the Notice to Property Owners and Memorandum of Understanding (MOU) being sent to riverfront property owners who will have HESCO barriers installed on their property.

CBJ distributed copies of the Notice to Property Owners and the Memorandum of Understanding to all affected property owners. Project managers in the field will have copies of the MOU and will work with property owners to document their unique circumstances and conditions.

Community Outreach

Engagement with the community regarding the authorization, funding, and execution of this project is critical to successful implementation.  Formal outreach and engagement opportunities will continue to be scheduled (Assembly meetings, Neighborhood meetings, public presentations, and more).  Links to all the public meetings and associated meeting packets and recordings can be found under the “Public Meetings” section of the CBJ Flood Response webpage. Additionally, questions, concerns, and comments can be directed to [email protected].

Relevant Resources

Links to all of the public meetings and associated meeting packets and recordings can be found under the “Public Meetings” section of the CBJ Flood Response webpage.

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