A short walk down the trail from the end of St. Anns Avenue on Douglas Island, a bright orange plastic fence circles the site of an old oil tank in the Treadwell Mine complex.
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Juneau’s historic Treadwell Gold Mine is a beloved city park with trails and a nine-hole frisbee golf course weaving through the ruins. Hole two was placed between the graffiti-covered concrete remains of the Central Power Plant and the ragged metal rim of an old oil tank where crude oil burbled up. This summer, the state plans to investigate how far the pollution has spread so it can get cleaned up.
Marc Wheeler, the director of parks and recreation for the City and Borough of Juneau, says a resident first reported an oil sheen at the site in August 2025.
“It seemed to have made its way to the surface last summer,” Wheeler said.
He said this oil is thick.
“They used bunker fuel, so it’s similar to what the cruise ships use,” he said. “It’s a very dense kind of tar-like fuel source.”
But miners must have put it there more than a century ago. So, why has it only recently risen up? Since oil floats on water, it’s possible that rainfall saturating the soil in the area buoyed blobs of oil to the surface over time.
Paulette Simpson, president of the Treadwell Historical Society, says this oil tank was one of several. They were part of the mine’s wintertime energy transition from coal to oil.
“The first oil tanks went in in 1907 and they were there for 10 years until the mine collapsed in ’17, and then they were drained and — my understanding — cut off,” Simpson said.
This one is called day oil tank number 8. Simpson says it could hold 10,000 gallons of crude oil — enough to run the Central Power Plant next to it for 24 hours.
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The Alaska Treadwell Mining Company, responsible for leaving the oil behind, collapsed after a massive cave-in flooded most of the tunnels in 1917. At the time, there were no laws requiring mining companies to clean up their messes or to set aside funds for reclamation if the companies dissolved.
Any remaining contamination at Treadwell falls under the purview of the Alaska Department of Environmental Conservation. DEC’s brownfields program adopts abandoned industrial sites to clean them up.
Flannery Ballard is an environmental program specialist with the brownfields program. She says the first step is to study the problem. The state got a to do that this summer.
“One of the things we’re going to investigate with our initial sampling is just, has contamination made out of the ring?” she said. “If it has, how far widespread is it? How deep does it go?”
She said sampling will be limited to the oil tank site and the area immediately surrounding it. After the initial assessment, Ballard said DEC will decide whether to apply for more federal funds to clean it up.
Ballard says she doesn’t know how long it will take to clean up the pollution since DEC hasn’t yet studied how far it’s extended.
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