Coast Guard launches final cleanup operation in Delta’s ‘graveyard of ships’

Nearly four years after a Cold War-era warship slipped beneath the surface of Little Potato Slough, federal crews are cutting it apart piece by piece, a complex demolition effort aimed at removing the last in a trio of sunken vessels contaminating one of California’s most fragile waterways.

Divers worked below the surface this week, carving into the corroded hull of the HMCS Chaleur, a 152-foot decommissioned former WWII Canadian Navy patrol vessel and a later minesweeper following the war that has been partially submerged in the Sacramento-San Joaquin Delta near Stockton since 2021. 

From shore, the vessel looked skeletal,  its midsection collapsed, aluminum frame warped, and bow just cresting the tide.

“It’s leaking oil near municipal and agricultural water intakes,” said Lt. Cmdr. Mark Leahey, the U.S. Coast Guard’s incident commander overseeing the operation. “The discharge is in the vicinity of incredibly sensitive habitat, including breeding grounds for dozens of endangered species.”

A dismantling chosen by necessity 

The Chaleur is the final chapter in a hazardous trilogy. Nearby, the 293-foot cruise ship Aurora sank last year and was later refloated and removed. The 100-foot tug Mazapeta was hauled out in January after leaking 1,600 gallons of diesel into the channel. Both were salvaged intact.

But the Chaleur, built in 1957, cannot be removed the same way.

Its wooden planks, saturated with fuel and exposed to three years of sun and water, began weeping oil each summer, according to Leahey. The heat expanded the timbers, releasing a constant oily sheen into waters that feed Stockton’s drinking supply and irrigate surrounding farmland. The Coast Guard has already removed approximately 2000 gallons of leaked oil. 

“With heat, the wood expands and oil is released,” Leahey said. “Containment booms work in the short term, but they’re not sustainable. This had to go.”

Delay, then demolition

Originally slated for earlier in the summer, the operation was delayed by permitting hurdles and snags in the supply chain. According to an internal update shared with contractors, the delivery of a plastic barrier, critical for containing debris, was pushed to July 7. 

Crews began mobilizing the following week, with full demolition expected to continue through August.

This week marked the first visible phase of the clean-up operation. Divers in full gear worked blind beneath the wreck, slicing it into sections with the goal of not agitating onboard toxins. The vessel, Leahey confirmed, still contains residual oil, asbestos and lead compounds.

The strategy

The Coast Guard contracted with Power Engineering Construction of Alameda to lead the dismantling. Using a floating crane, excavator and two material barges, the crew will cut the Chaleur into sections underwater and lift each piece for transportation to a licensed disposal facility.

“We’re going to be cutting the vessel into four pieces and craning out each piece onto the barges,” Leahey explained. “The largest piece weighs about 300,000 pounds and it’ll be craned onto the materials barge.”

A turbidity curtain will surround the site, trapping sediment and debris. The work is pad for by the federal Oil Spill Liability Trust Fund, administered by the U.S. Coast Guard’s National Pollution Funds Center (NPFC) and used when no viable party can be held accountable for pollution. 

Created under the 1990 Oil Pollution Act, the Trust Fund maintains a $1 billion principal reserve, sourced mainly from a per-barrel oil tax and other fees, and a separate Emergency Fund that disburses up to $50 million annually, with an additional $100  million available if needed, for rapid removal responses. 

“We spent about a year working on the funding proposal to get authorization and funding to destroy the Chaleur,” Leahey said. 

According to the Coast Guard, NPFC manages this fund around the clock to ensure federal on-scene coordinators can immediately respond to threats, cover containment and cleanup costs, seek natural resource damage assessments, and recover expenses from responsible parties when possible

In 2019, the Coast Guard utilized the fund in the salvage of the MV Golden Ray, a car carrier that capsized off the coast of Georgia. The response included cutting the 656-foot vessel into sections and removing over 400,000 gallons of fuel. 

An anchor of neglect

Decommissioned in the 1990s and sold for scrap, the Chaleur somehow ended up beached at Herman and Helen’s Marina off Eight Mile Road. It sank entirely by 2021, becoming one of the many abandoned vessels littering the Delta’s arterial sloughs.

“This is just one hotspot,” Leahey said. “There are dozens more wrecks throughout the Sacramento–San Joaquin Delta. This one just happened to threaten water, wildlife and people all at once.”

The region’s labyrinth of waterways has become a graveyard for derelict boats, many of them forgotten until they sink or spill. Environmental advocates say enforcement remains weak and accountability is rare.

Once the Chaleur is gone, the slough will be clear of major wrecks for the first time in years. But the larger Delta remains vulnerable, with no centralized agency assigned to monitor or prevent vessel abandonment.

When pollution meets collapse 

The environmental stakes surrounding the Chaleur’s removal are heightened by the broader vulnerability of the San Joaquin River, where water quality has declined sharply in recent decades. In a report by Restore the Delta, the organization says that “the water quality of the lower San Joaquin River has decreased markedly… coinciding with flow reductions, population growth, and expanded agricultural production.” 

The report cites pollutants including “dissolved oxygen, salinity and boron, nutrients, trace metals, and pesticides” as key threats to fish and wildlife. The presence of sunken, oil-leaking vessels like the Chaleur, located in close proximity to drinking water and irrigation intakes, compounds the risk in an already impaired system.

As demolition crews continue their work beneath the surface of Little Potato Slough, the Chaleur’s removal signals a rare victory in the uphill battle against derelict vessels across California’s Delta. But for the Coast Guard and local officials, it’s also a reminder of how easily one abandoned ship can spiral into a regional threat.

“We hope people see what it takes to clean these up, because once they sink, it’s not just a boat problem anymore,” Leahey said. “It’s a public health and environmental crisis.”

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