Fort Bragg’s old Mill Pond dam heads into a possibly record El Niño

FORT BRAGG, CA., 11/3/26 — Mendocino Railway owes the state its answers on how to clean up Fort Bragg’s Mill Pond by Tuesday, Nov. 17. One week later, the first of this winter’s king tides reaches Soldier Bay, at the foot of the pond’s old dam.

Forecasters expect a strong El Niño. The ocean off the coast is already running high. And the state Department of Toxic Substances Control has sent the railway’s cleanup study back, asking, among other things, how the dam and the beach in front of it will hold up.

What’s behind the dam

On the map, it’s called Pond 8. In town it’s the Mill Pond. It covers about 7.3 acres and holds about 106,000 cubic yards of sediment contaminated with dioxins, according to a 2019 cleanup study. The highest reading was 243 parts per trillion, measured as toxic equivalents. The state’s draft cleanup goal is 53 parts per trillion.

Holding it back is a dam with a crib wall of old redwood timbers facing the sea. After an earthquake in 1898, the town’s newspaper reported that “the dam at the mill pond cracked in the middle.”

The pond still takes the city’s storm water. Two city pipes empty into its east side, carrying about 40% of the city’s storm water, the state’s 2007 cleanup order says. When the pond is full, water spills over the dam onto the beach. Between 2006 and 2010, dioxin in the outflow topped the state’s water quality objective in nine of 13 samples.

Mendocino Railway, which runs the Skunk Train, took most of the mill site from Georgia-Pacific in a 2021 eminent domain settlement and “expressly assumes any and all liability” for contamination on the land, the court judgment says. The state’s cleanup order also names Georgia-Pacific and a railway affiliate, Sierra Northern Railway.

The land has also changed hands. In January, Sierra Northern deeded mill-site parcels to Sierra Railroad Holdings LLC, a company formed seven weeks earlier, county and state records show. The toxics department’s Aug. 19 letter went to Mendocino Railway and Sierra Northern, not Sierra Railroad Holdings.

A deadline already passed

The state Division of Safety of Dams has limited how high the pond can be filled since 2010. That year, it told Georgia-Pacific that sand in the dam “has the potential to liquefy” in a major earthquake, and it agreed with the company’s plan “to remove the dam from service as soon as possible,” by 2015.

The dam is still there. The division extended the deadline to 2020, then gave the owner until Dec. 31, 2025, to fix the dam’s safety problems. A Dec. 19, 2025, memo in the division’s file showed the 2010 fill-limit still in place. The division’s file from October 2025 through April 2026 holds no letter extending the deadline.

The division’s June inspection report says, “The dam is seismically deficient,” and rates it “safe for interim use” while a repair application filed in April 2022 is under review.

The question the state keeps asking

The toxics department raised the danger with Georgia-Pacific in 2018. “A release of contaminated sediment to the ocean because of containment failure could result in considerable public health and environmental impacts,” it wrote. On Aug. 19 of this year, it asked the railway again how each cleanup option would hold up against climate change and rising seas.

Nov. 17 falls five years to the day after the eminent domain settlement was filed. Mendocino Railway asked the department for more time on an earlier step of this same study in April 2024. The state expects a draft cleanup plan for the ponds in 2028.

What stands between the pond and the sea

Between the dam and the surf is a beach berm. Mendocino Railway’s 2025 update to its cleanup study counts the dam and the berm as containment and says the berm would keep protecting the dam from the ocean.

In its Aug. 19 letter, the toxics department asked the railway to show “that the existing berm is currently keeping sediment in place.”

A high sea and a strong El Niño

At Arena Cove, the nearest federal tide gauge, mean sea level in September was the highest for any September in records back to 1978, about 8 inches above the gauge’s long-term average.

The federal Climate Prediction Center, in its Oct. 8 update, put the chance at 83% that this El Niño will be stronger from October through December than any on record since 1950.

Fraser Shilling, director of the Road Ecology Center at UC Davis, said in an Oct. 23 interview that sea level on the California coast is up about a foot higher than in recorded history, and a Kelvin wave from this El Niño adds about another foot. The rest, he said, comes from warm water expanding and back-to-back storms pushing water against the coast. “So it’s not just one foot of sea level rise, it’s three feet of all of the above,” he said.

John Largier, a UC Davis oceanographer, counted five things that can raise the water at once: king tides, the long-term rise in sea level, El Niño, river water and the weather. “If you get the perfect storm, it will be really bad,” he said in a Sept. 30 interview. “If they don’t all align, then it might be okay.”

Peter McNamee, a member of the Noyo Headlands Working Group, a citizen group that has pushed the state for a fuller cleanup, said in an Oct. 27 interview that higher water sends waves into the bluff and the dam instead of the sand, and washes out the sand at the base. “And so the base of the dam then becomes more susceptible to erosion,” he said.

The California Coastal Commission lists this winter’s king tides for Nov. 24-26, Dec. 23-25 and Jan. 21-22. NOAA predicts the highest tide of the year at Arena Cove at 10:02 a.m. on Christmas Eve, 7.62 feet, assuming a normal ocean. Its threshold for minor flooding there is 7.75 feet. If the ocean is still running about 8 inches high then, that tide could reach about 8.3 feet.

Shilling said Christmas worries him more than Thanksgiving, because more storms will have soaked the ground by then. “The timing is everything,” he said.

Robert Pinoli, president and CEO of Mendocino Railway, hasn’t answered written questions sent Sept. 24 about the mill site and the dam. Georgia-Pacific declined to comment in September.

This is the first of a series of stories about the past, present and future of the Fort Bragg mill site.