Juneau leaders say Army Corps pulled earlier direction on lake‑tap tunnel after charrette; staff urge stronger advocacy

Mayor Weldon convened the Committee of the Whole on Feb. 23 for a technical briefing on glacial outburst flood (GLOF) risk and long‑term mitigation options following a December Army Corps of Engineers charrette.

Director Koch said the Army Corps and its consultants — including AECOM and University of Alaska Southeast scientists — modeled a worst‑case peak flow that could reach about 118,000 cubic feet per second (CFS), a “scary” peak value that combines potential GLOF contributions with extreme precipitation and atmospheric‑river influences. Koch noted prior events the city has experienced: an approximately 34,000 CFS event in August 2023 that affected about 30 homes and an approximately 42,000 CFS event in August 2024 that inundated roughly 300 homes. She said HESCO Phase 1 barriers deployed in 2025 protected many locations but were not designed to stop the largest modeled events.

Koch described the charrette’s technical comparison of options and said a lake‑tap tunnel — a gravity‑fed intake in Suicide Basin with a roughly 2.3‑mile tunnel and 10‑foot internal diameter — was the preferred alternative among many agencies because it would reduce risk without requiring mass relocation of properties. She summarized the charrette’s numeric assessment that a relocation alternative could affect as many as 2,855 properties, and said the lake tap’s preliminary designs suggested it would be the least operationally complex option.

But Manager Kester told the Assembly that, in a meeting last week with Army Corps headquarters, the Corps rescinded the earlier direction that had been steering the project toward a lake‑tap as the selected alternative and instead instructed its team to wrap up lake‑tap‑specific engineering and to prepare a report describing all five alternatives. “They directed staff to wrap up all efforts on the Lake Tap as the selected alternative,” Kester said, adding that the Corps emphasized a shift toward “expanded flood fighting, flood walls, reinforcing those Hesco barriers” as a near‑term or midterm focus.

Kester and other staff said the pivot left CBJ staff and many Assembly members frustrated and seeking clarity. Kester said she had already arranged a meeting with Senator Sullivan’s office and the Army Corps’ assistant secretary’s office and that the city had engaged Senators Murkowski and the district’s congressman as allies. “We will be pushing very hard to pivot to get this train back on tracks to a lake tap,” she said.

Deputy Director Nate Ramsey detailed near‑term flood‑fighting work: he said Sea Alaska Construction Solutions is the Army Corps’ general contractor and that Sea Alaska and the Corps anticipated project managers stationed in Juneau for Phase 2, with installations scheduled to begin by mid‑March, weather permitting. Ramsey also said reinforcing and raising Phase 1 alignments will be required and that maintenance and repair needs appear substantially greater than first estimated.

Staff repeatedly cautioned that the 118,000‑CFS estimate is a peak, worst‑case value based on Corps modeling and multiple inputs (USGS, NWS, hydrologic subcontractors) and that geotechnical and design work remain preliminary. The manager noted a congressionally directed $6 million request to fund geotechnical investigation for a lake‑tap option; staff said geotech is expensive and critical to narrowing feasibility and cost estimates.

Assembly members asked how the new worst‑case numbers changed emergency planning, whether HESCO barriers could be scaled for View Drive, and whether CBJ could begin local geotechnical work to accelerate design. Staff replied that emergency response would be informed with more lead time when a GLOF is detected, that View Drive is a poor fit for HESCO barriers at reasonable heights, and that local geotech could help but may not match federal teams’ specifications. Deputy Director Ramsey said Phase 2 flood‑fighting work and near‑term HESCO raising remain essential regardless of the Corps’ longer‑term planning timeline.

Kester closed by asking the public to rally support for an enduring solution and for a united message to the delegation as the city seeks answers at a scheduled meeting with the Corps on Wednesday.

Next steps: CBJ staff said they will continue to press the Corps for clarification, pursue geotechnical funding, coordinate with the delegation, and proceed with reinforcing Phase 1 as Phase 2 work advances.