BAKER CITY — Idaho Power Co. will replace one of the three generators at its Hells Canyon Dam on the Snake River, about one-third of the 53-year-old dam’s 391,500-kilowatt generating capacity.

“The work beginning this week is part of Idaho Power’s long-term maintenance plan for the Hells Canyon Power Plant,” company spokesman Brad Bowlin said. It’s expected to conclude in spring.

Boise-based Idaho Power is developing a staging area at the Eagle Bar recreation site outside Oxbow to support various maintenance and construction projects over the next 10-plus years, he said. Some public access will be limited.

“The first step is replacing one of the three generators,” he said. “A second generator is scheduled to be replaced next year.”

The utility also plans to modernize control systems and other equipment.

“One of the things we have to do more is to ramp more facilities up and down” as the company integrates renewables, such as wind and solar, Bowlin said. “That is a benefit of hydro, but it does cause additional wear and tear on the unit. If we have better controls, it’s in a way more efficient and helps extend the life of the equipment.”

Idaho Power plans to eventually replace the power plant’s third generator and turbines, expand the fish trap, perform maintenance on the spillway, and build flow deflectors to address water-quality requirements, he said.

“Some of this work is contingent on receiving a new federal license for the Hells Canyon Complex,” Bowlin said. “Currently, we expect that to happen no sooner than the beginning of 2022.”

Current and planned work aims to extend the power plant’s useful life and increase its efficiency.

Upstream water users aren’t expected to see impacts, Bowlin said. Downstream, “we should see improved water-quality conditions downstream and improved fish collection, sorting and monitoring abilities.”

The combined projects are expected to cost around $120 million.

The work is part of the company’s effort to provide reliable electricity at the lowest-possible cost to irrigators and other customers, Bowlin said. Idaho Power’s lowest-cost generation comes from its 17 hydroelectric facilities, and “we’re constantly trying to make sure everything is in good repair.”

For example, the company has been working on generators at Brownlee Dam, the uppermost of the three dams in the Hells Canyon complex.

Oxbow Dam, in the middle of the complex and the smallest, is not ramped up and down as often as the others, Bowlin said. Its generators are scheduled to be overhauled in the 2023-28 period.