Juneau leaders ask Army Corps why it reversed on long-term glacial outburst flood solution

Since the U.S. Army Corps of Engineers pulled back its decision to design a lake tap that would put a stop to annual glacial outburst flooding in Juneau’s Mendenhall Valley, local and congressional leaders have pressed the agency to explain why. 

Until recently, the Army Corps was pursuing the lake tap solution, which would involve digging a tunnel through Bullard Mountain to continuously drain the glacial basin that fills with rain and meltwater, so the water can’t rush out all at once each year. It would work like a bathtub drain. The idea drew broad local support. 

Juneau’s city leaders say they’re concerned this change will delay a long-term solution. U.S. Sen. Dan Sullivan asked the Army Corps for transparency at a U.S. Senate Committee on Environment and Public Works hearing on Wednesday. 

“There is this perception that things are going dark, people are nervous again that the Corps is not engaged,” Sullivan said. 

Adam Telle, Assistant Secretary of the Army for Civil Works, said this change of course is not a pull-back on the agency’s commitment to protecting the Valley from flooding.

“We’re committed to a short, medium and long-term solution for the challenge that faces Juneau,” he said at the hearing. 

Lt. Gen. William Graham, chief of engineers and commanding general at the Army Corps, told Sullivan that the agency will take more time to evaluate all of the options for a long-term solution. Besides a lake tap, those options are a dam at the outlet of Mendenhall Lake, a permanent levee along Mendenhall River, a bypass channel through the floodplain or relocating impacted residents.

“It’s too soon to take any options off the table, because what we’re wrestling with most here is time,” Graham said. 

He said if the agency moves ahead with the lake tap, the temporary levee could fail before a tunnel is completed — meaning the Valley could get hit by catastrophic flooding again. The temporary levee protected most Valley homes from a record-breaking flood last summer, but water rose within inches of the top and seeped through some areas. Graham said the Army Corps wants to look for an intermediate solution. 

Juneau City Manager Katie Koester posted an update on Friday saying she is “deeply concerned” about the uncertainty around a long-term solution. Last week, the city submitted an $8 million congressionally directed spending request to fund a plan for a lake tap. She wrote that the city will “keep the pressure on” and invited residents to continue advocating for a solution that will protect the Valley in the long run.