The navigation lock at The Dalles Dam on the Columbia River will be closed for repairs for five weeks early next year.

That’s three weeks longer than the usual two-week closure for repairs each year.

The U.S. Army Corps of Engineers anticipates the closure will be from mid-February to mid-March.

Inspections of the navigation lock downstream miter gate revealed a crack in the skinplate, said David Tucker, Portland District project manager for the Corps.

Technicians took temporary measures to strengthen the gate near the crack and shimmed sealing surfaces to reduce the leakage.

“We anticipate that those measures will stop crack growth and improve sealing and load distribution on the gate until we can make permanent repairs,” Tucker said.

The temporary repairs have minimized additional damage to the gate and the Corps is confident it will perform adequately until it is permanently repaired.

The Corps is visually monitoring the temporary repairs with a submersible vehicle in addition to what technicians observe, including climbing inspections, Tucker said.

They also installed additional sensors on the gate.

“We do have some additional concerns about some filling and draining valves at the bottom of the lock,” Tucker said. Issues with the valves have been addressed with temporary measures while the Corps finalizes designs for long-term repairs.

“The temporary repairs are performing well and with two sets each of fill and drain valves there is redundancy in those systems,” Tucker said. “Everything considered, we have a good level of confidence that we will be able to address those issues with proper planning.”

The Corps estimates the repairs will cost between $1 million and $5 million. Cost of other activities to support the effort, such as project management, design, contract administration and emergency repairs already completed are $3 million.

Funding for the project to date has come from reprogramming, reallocations, and funding from Corps headquarters, Tucker said.

“We’re very glad the Corps is getting after this issue in a planned fashion, and have already started outreach to folks regarding the additional weeks that will be required early next spring,” said Kristin Meira, Pacific Northwest Waterways Association’s executive director. “This is definitely a good news story, overall, when we think about the right way to make repairs to infrastructure such that commerce is minimally disrupted.”

Glen Squires, CEO of the Washington Grain Commission, doesn’t anticipate any inability to meet customer demands.

“That’s a point where a lot of wheat goes through upriver,” Squires said. “Knowing in advance certainly helps. It’s always better than just to shut down when it’s not planned.”

The Columbia-Snake river system was previously closed for extended periods of time, for 15 weeks in December 2010 to March 2011 and 14 weeks in December 2016 to March 2017.