Sitka’s Green Lake Dam back in service

After 84 days out of commission, the Green Lake Dam is up and running again. The dam works in tandem with the Blue Lake Dam to provide hydropower to Sitka. (Photo by Rebecca Danon/KCAW)

On Jan. 7, the Green Lake dam was fully restored to service. The city is no longer using diesel fuel.

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The dam was shut down in October when part of the intake gate, which controls water into the powerhouse, failed during a routine inspection. The part – a hydraulic cylinder that raises and lowers the gate – was housed in carbon steel. After 35 years underwater, it corroded and began leaking fluid. The replacement hydraulic cylinder should last longer, because it’s housed in stainless steel.

It arrived in Sitka by barge on Jan. 3 and was installed at 11:30 a.m on Jan. 7. The Green Lake Powerhouse is up and running with one turbine, while the city is making a small repair on the second turbine.

Utility Director Bryan Bertacchi said that making this fix was a group effort, from the mechanics descending 165 feet to the bottom of the dam to city crews keeping road clear to emergency responders standing by, in case there was an accident.

The hydraulic cylinder sits at the bottom of this 160 foot shaft. Mechanics with the Electric Department access it by climbing down a steel ladder, using a harness and safety clips. (Photo by Rebecca Danon/KCAW)

“It was a real incredible team effort in a small community with a small number of people to get that done in the time that it got done,” Bertacchi said.

The city of Sitka owns its electric utility, which is normally 100% hydropower – combining both the Blue Lake and Green Lake Dams. While the Green Lake Dam was out of commission, the city ran diesel generators during cold snaps. All told, the city burned through about 80% of its diesel budget for the year.

“It depended on the weather right? On some warm days, we didn’t run diesel at all and then on real cold days, we ran up to like 18 hours days diesel. We burned through $270,000 of those $337,000 dollars, so we’re still under the budget. So we don’t anticipate at this time any additional diesel surcharge at this time in our electric rates,” Bertacchi said.

The Green Lake Power plant is in serious need of an overhaul. In 2019, Bertacchi said the city plans to shut the plant down for a major repair. And that’s not the only thing that needs to be fixed in the next decade.

“We really need to do a major overhaul of the Marine Street Substation,” Bertacchi said. “That’s really important. That substation serves 80% of the entire community. We want to make sure that’s working well during our high peak tourism season and for fish processing.”

To pay for this and other aging infrastructure, the city will also use leftover bond money from the Blue Lake Dam expansion project – which totals about $22 million within the next 10 years.