USACE rescinds promise to pursue lake tap as long-term flood solution
- Jasz Garrett
- 19 hours ago
- 4 min read
'Disheartening pivot' leaves CBJ leaders 'a little bit speechless' as assessment of worst-case flood-level scenario rises significantly
By Jasz Garrett and Mark Sabbatini
Juneau Independent
Correction: The U.S. Geological Survey was previously reported to be at the three-day charrette, according to information from USACE and CBJ. USGS told the Juneau Independent that the agency was not present.
The U.S. Army Corps of Engineers has pulled back from studying a preferred long-term solution for glacial lake outburst floods, according to the City and Borough of Juneau.
City Manager Katie Koester announced what she called disappointing news during a Committee of the Whole work session on Monday. She said the federal agency still promised to consider the outlined five long-term alternatives, but would no longer be primarily focusing on the lake tap. She said the city was notified of the change on Thursday.
Koester said she did not understand why the agency's direction changed and hoped to learn more in a meeting scheduled with Sen. Dan Sullivan's office this week.
“They used words like, 'If there's ever an enduring solution,' and put it on a time frame of decades and not years,” Koester said. “I can assure you that our immediate next outreach was to our Sen. Sullivan, who remains committed to an enduring solution for the City and Borough of Juneau.”
The lake tap solution was not authorized to move forward on construction or funding, but its selection was meant to move the publication date of a technical report for public review to May.
That report is still expected to be submitted by USACE this spring, but it will now survey the five long-term solution options. This could significantly lengthen the timeline to implementing a long-term solution, according to CBJ.
The announcement, called shocking by some Assembly members, came immediately after city engineers said floods in future years may far exceed previous worst-case scenarios. Record floods have crested at about 15, 16 and 16.65 feet during the past three years, and a top-end scenario presented Monday could result in a crest of 22.5 feet. Flood inundation maps for a worst-case scenario last year showed a Mendenhall River crest of 20 feet.
A lake tap was deemed the best option for USACE to study by the city, the Central Council of Tlingit and Haida Indian Tribes of Alaska, and the U.S. Forest Service during a three-day USACE charrette in December.
The 2023 flood saw a flow of 34,000 cubic feet per second, the 2024 flood 42,000 cfs, and a preliminary estimate of the 2025 flood is more than 51,000 cfs.
In her presentation to the Juneau Assembly, CBJ Engineering Director Denise Koch explained why the lake tap is a desirable solution and called the worst-case flood scenario “sobering.”
Koch’s presentation included a “design peak flow” of 118,000 cfs, with inundation maps at that level showing most of the Mendenhall Valley submerged without protective measures.
The worst-case flood scenario of 118,000 cfs was determined at the December charette by USACE, in conjunction with subject matter experts from AECON, University of Alaska Southeast and the National Weather Service.
Koch and Koester both remained adamant the lake tap is the best solution for long-term flood mitigation and said they would continue their advocacy with Alaska’s federal delegation.
“The call to action that I would ask is to advocate for a lake tap,” Koester said. “This community needs to be very singularly focused and together on what we need and demand for the survival of our community.”
Residents living in the flood zone who attended Monday's meeting expressed shock and declined comment as they processed the information.
The Trump administration has frozen other funding from the Army Corps of Engineers, most notably $11 billion in projects last fall in a dozen states mostly led by Democratic governors. Also, CBJ, as of earlier this month, had not received any of its expected Federal Emergency Management Agency funds for public assistance projects after the 2024 glacial flood.
The Corps of Engineers is still expected to honor a short-term agreement with CBJ to pay for and install a second phase of HESCO barriers before this year’s flood season, extending the current levee in both directions, according to city administrators. Officials said when the agreement was signed last October it would save the city about $17.5 million for the work, based on the nearly $8 million local cost for the first phase of barriers.
Nate Rumsey, CBJ’s deputy director of public works, said Monday those general parameters are still accurate, but the scope of the work is changing. One part will include repairing and reinforcing the first stage of barriers, including making some higher due to potentially higher levels of flooding than previously expected. Also, some of the areas included in the second phrase of barriers — extending as far as the perimeter of Juneau International Airport, well away from the major damage zones — “didn't see a lot of direct flooding from the river at all.”
More specifics about the second phase of the project are scheduled to be discussed with USACE engineer officials Tuesday, Rumsey said.
He said the city already has the barriers in its possession, so there isn’t a concern about the federal agency revoking that agreement. The city is responsible for the ongoing maintenance of the barriers once they are installed.
However, Rumsey said, those barriers “are likely not the answer to our problems” if a worst-case flood under the new projections occurs. He said an enduring solution is needed.
• Contact Jasz Garrett at jasz@juneauindependent.com or (907) 723-9356. Contact Mark Sabbatini at editor@juneauindependent.com or (907) 957-2306.
