Juneau assembly directs manager to extend HESCO flood barriers for Phase 1A after inundation maps released

Summary

The City and Borough of Juneau heard new two‑dimensional inundation maps May 12 showing HESCO barriers reduce flooding at modeled stages; the assembly gave the manager direction to proceed with Phase 1A barrier extension by unanimous consent and asked staff to pursue outreach, modeling and funding options for a Phase 1B extension.

The City and Borough of Juneau Assembly met May 12 in a special Committee of the Whole to review newly released inundation maps and to give immediate direction on continuing HESCO flood‑fighting barriers in the Mendenhall Valley. Assemblymembers voted, by unanimous consent, to direct the manager to move forward with a Phase 1A extension of the HESCO barriers and asked staff to return with outreach and modeling for a possible Phase 1B extension.

The maps presented to the assembly model two‑dimensional flood spread at multiple stage heights on the USGS Mendenhall Lake gauge and compare conditions with and without installed HESCO barriers. “PESCO barriers phase 1 works as intended,” the city manager said while introducing the maps. Garrett Yeager, surface water manager with Michael Baker International, the consulting firm that developed the modeling, told the assembly that the team used lidar, high‑water marks from recent events and National Weather Service hydrographs to calibrate a HEC‑RAS 2D model and that the model was validated against 2024 observations.

Why it matters: the maps are intended to inform short‑term flood‑fighting (barrier placement and emergency response) and long‑term mitigation planning. Staff said HESCO barriers substantially…

Juneau assembly directs manager to extend HESCO flood barriers for Phase 1A after inundation maps released

Summary

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