Army Corps completes Phase 2 of short-term flood mitigation in Mendenhall Valley

Jasz Garrett
6 hours ago
3 min read

Construction completes as bill to expedite long-term glacial outburst flood solution heads to U.S. Senate

By Jasz Garrett

Juneau Independent

The U.S. Army Corps of Engineers announced Friday it completed the second phase of temporary flood mitigation measures in the Mendenhall Valley ahead of this year’s outburst.

“Our community is heading into a 2026 glacial lake outburst flood with a much higher level of protection than we have ever had,” said Deputy City Manager Robert Barr in a prepared statement.

The HESCO barriers are designed to increase protection from annual glacial lake outburst floods.

The Army Corps installed 2.72 miles of gabion baskets along the Mendenhall River and armored 1.85 miles of riverbank to prevent erosion. The federal agency also constructed a 1,100-foot-long earthen berm to protect Back Loop Road and downstream areas, according to the release.

“To address overtopping risks near neighborhoods and the Mendenhall River Community School, USACE, CBJ, and the U.S. Forest Service opted to build an efficient low-maintenance earthen berm along the lake side of Back Loop Road,” the release states. “Located on two acres of Forest Service land between Back Loop Bridge and Chelsea Court, the berm stands 10-12 feet high and 50-60 feet wide.”

The earthen berm near Back Loop Road is seen during its construction on July 11, 2026. (Jasz Garrett / Juneau Independent)

Last October, the agency signed an agreement with the City and Borough of Juneau to federally fund the Phase 2 barrier installation.

To date, Phase 2 has cost approximately $35 million, involving over 30,000 contractor labor hours and 7,000 Army Corps project delivery team hours, according to the release.

Last year was the first time the HESCO barriers were utilized, and while the city estimated they offered protection to 90% of homes, water seeped underneath and a tree struck one basket near Dimond Park.

Ahead of this year’s glacial outburst, the Army Corps shipped 41 pumps to Juneau and cut roughly 200 downed trees to reduce debris strikes on the HESCO barriers.

“This builds on the highly effective Phase 1 barriers installed in spring 2025, which covered 2.5 miles between Marion Drive and Rivercourt Way, incorporating important lessons learned from the 2025 GLOF,” the Army Corps news release states.

A pump staging map is available on the city's guide to flood preparedness website.

Barr said the Army Corps’ Advanced Measures program and its teams are helping to protect thousands of homes, businesses and properties, including schools and critical infrastructure.

“We are incredibly grateful, not just for their work on Phase 2, but for their collaboration across all aspects of this ongoing disaster,” he said.

Adam Telle, assistant secretary of the Army for Civil Works, thanked President Donald Trump, Sen. Dan Sullivan and the Army’s commitment to “Building Infrastructure, Not Paperwork” for the additional protection this year.

“We cannot have the capital of one of our most important states, Juneau, Alaska, endure this flooding every summer. It’s unacceptable,” Sullivan, R-Alaska, said in a prepared statement.

The Water Resources Development Act passed out of the U.S. Senate Environment and Public Works Committee on July 15. The legislation is a key step toward accelerating the Army Corps’ long-term response to flooding in Juneau, according to the press release.

“The HESCO barriers are now complete as a short-term solution,” Sullivan said. “The WRDA bill we passed out of committee last week empowers the Army Corps to rapidly solve this crisis for Juneau while we continue working on medium- and long-term solutions.”

At the hearing, he said the bill aims to fast-track a permanent engineering solution by speeding up Army Corps paperwork.

City Manager Katie Koester said the bill's language could help authorize a project for a long-term solution.

“It doesn't fund the project, but it authorizes it as an Army Corps project, which paves the way then for future funding,” she said in an interview. “We've been working this whole time towards this WRDA authorization.”

Congress would still need to appropriate funding. Additionally, the bill still must pass the U.S. Senate and House.

“Secretary Telle has really been trying to make sure that we're covered in the short term with the HESCO barriers — in the mid-term while we wait for a longer-term solution,” Koester added. “We're really working and the Corps is really working all angles trying to keep all those doors open and doing their due diligence.”

• Contact Jasz Garrett at jasz@juneauindependent.com or (907) 723-9356.