Army Corps completes second phase of temporary Mendenhall Valley flood barriers

The U.S. Army Corps of Engineers completed Phase 2 of temporary flood-mitigation measures in Juneau’s Mendenhall River Valley on July 24, the agency announced.

The work is intended to increase protection for Juneau from glacial lake outburst floods. It follows earlier Phase 1 mitigation work and is part of a broader effort involving near-, mid- and long-term flood-protection planning.

Temporary measures ahead of recurring threat

Juneau has faced repeated flood threats associated with releases from Suicide Basin above the Mendenhall Glacier. The Army Corps described the completed work as temporary mitigation for the Mendenhall River Valley, where those releases can produce glacial lake outburst flooding.

The announcement does not say how many barriers were installed, how many people or properties are protected, or how much the work cost. It also does not provide a quantified estimate of how much flood levels may be reduced.

The measures are intended to increase protection, not eliminate flood risk. The available information does not establish whether a flood will occur in 2026 or what level any future flooding could reach.

City work accompanied federal project

The City and Borough of Juneau has been carrying out related short-term barrier work. The city said Phase 1 reconstruction and repairs were complete July 10.

On its flood short-term-solutions page, the city also listed final flood-barrier openings as being closed during the week of July 21. That work includes Phase 1 and Phase 2 HESCO barrier construction and related flood-modeling work.

The Army Corps’ July 24 announcement marks completion of its second phase of temporary measures. The city’s listed closure work was the next identified short-term action in the available public updates.

What remains unresolved

The completed work is one part of a larger protection effort rather than a permanent flood-control solution. Publicly available information in the Army Corps announcement does not set out a final cost, a protected-population total or a final measure of expected flood reduction.

For residents of the Mendenhall River Valley, the significance is immediate: federal and city agencies have advanced temporary barriers and related work intended to improve protection from a recurring flood hazard tied to the glacier system above Juneau.