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The un-mysterious “Mystery Sheen”: Tikahtnu is NOT Hilcorp’s honey bucket

by | Sep 16, 2026 | Clean Water, Energy & Alaska, Oil & Gas

The recent Trading Bay “mystery” sheens are just the latest warning sign of industry neglect. Every leak and spill puts our waters, workers, and communities at risk, and these infrastructure failures will only get worse.

Much of Cook Inlet | Tikahtnu’s offshore oil and gas infrastructure is decades old and increasingly susceptible to leaks and failures. One of the hazards is “produced water,” a toxic, chemical-laden fluid that comes up with oil and gas. As pipelines and platforms rust and weaken, the risk of spills rises, threatening the health of our waters, ecosystems, fisheries, and communities. Comprehensive measures are necessary to prevent further harm and to hold operators accountable for proper maintenance and cleanup.

Two oil sheens recently appeared near Hilcorp’s inactive Spark platform in Trading Bay. The first, five-mile-long slick disappeared before anyone could pin down the source. State agencies, the Coast Guard, and Hilcorp scrambled to investigate, but even after testing pipelines from the Granite Point Tank Farm, the leak and substance remain a mystery.

Last Wednesday’s test by Hilcorp to find the leak produced an oily sheen after engineers with the company, the Department of Environmental Conservation, and the Coast Guard restarted an outfall pipeline from the Granite Point Tank Farm near Tyonek on the western shores of Tikahtnu. This second sheen was blamed on produced water. All signs point to the Granite Point and Spark platform network, but no one has admitted exactly where the failure is located.

Hilcorp claims it shut down the test after 15 minutes and sent a boat to contain the spill. But it’s still unclear if anyone bothered to collect a proper water sample, even though responders were right there. This dearth of transparency leaves us in the dark about what actually ended up in Tikahtnu and shows just how little accountability, if any, there is when spills continue to happen.

DEC said the outfall line carrying produced water from the Granite Point Tank Farm ends at the Spark Platform, and the line will remain shut in while Hilcorp continues to “investigate” the source of the sheen and plans are developed and reviewed by the Unified Command.​

Produced water is a toxic mixture of salty waste, oil, grease, toxic hydrocarbons, and heavy metals, including mercury, lead, cadmium, and arsenic. Pipelines carry this cocktail from wells to separation facilities, where it’s supposed to be handled safely, but as we’ve seen, leaks still happen. That is when they don’t just dump it straight into the Inlet under the guise of mixing zones. 

The Spark platform has been inactive since 1992, meaning it has been 34 years since it was last operational. Marathon plugged and cemented its individual wells in 2009. Even if the wells are plugged, leaving giant, unmaintained legacy steel structures standing for decades in a harsh marine ecosystem introduces unnecessary environmental risks. The Alaska Department of Natural Resources (DNR) Division of Oil & Gas has deferred the dismantling and removal of the physical steel platform structure above the water and has allowed the structural cleanup timeline to stretch significantly. As these structures age, the likelihood of leaks and spills increases, compounding the risk to our environment.

​Dismantlement, Removal, and Restoration (DR&R) is the legal and financial obligation of oil and gas operators to plug wells, remove offshore platforms or pipelines, and restore the site once a facility reaches the end of its working life. It prevents the State of Alaska or taxpayers from inheriting multi-million-dollar abandonment liabilities if an energy company goes bankrupt or abandons aging infrastructure. DNR oversees negotiations of DR&R agreements, bonding requirements, and unit operations in the basin while giving Hilcorp a free pass to pollute the Inlet.

Hilcorp’s track record raises legitimate concerns for Alaskans. The company has repeatedly delayed cleanup obligations, kept key financial information secret, and posted minimal bonds that fall far short of what’s needed for full decommissioning. This pattern of avoidance shifts financial risk onto the public: if Hilcorp walks away or postpones action, taxpayers could be left to foot the bill for dismantling aging oil and gas infrastructure. Without immediate and adequate bonding requirements, Alaskans face the real possibility of inheriting decades-old pollution and costly environmental hazards.

Requiring oil and gas companies to clean up promptly has clear benefits: it saves taxpayers money, protects our coastal communities and fisheries, creates local jobs, and allows valuable materials to be recycled instead of left to decay underwater. Proper decommissioning is not just good for the environment; it’s a smart economic choice for Alaska’s future.

While Hilcorp may argue that its phased approach to cleanup reflects the technical and financial challenges of decommissioning aging infrastructure, this strategy delays substantive removal efforts. As the operator of nearly every platform in the region, Hilcorp continues to defer the critical work of dismantling non-operational infrastructure, opting instead to squeeze out dwindling profits rather than address the menaces threatening the waters that sustain us.

​At the federal level, the House Natural Resources Committee held a full Committee Markup on Tuesday, including a bill that puts ocean life at risk while doing little to tackle the underlying threats facing our marine ecosystems.

Lawmakers are now considering Rep. Ezell’s H.R. 5745, a bill that would let oil and gas companies walk away from old platforms by pretending they’re creating habitat. This so-called Rigs-to-Reefs plan is more about saving corporate profits than protecting the environment. In reality, leaving decaying platforms in place exposes the public to long-term liability, increases risks of pollution, and can introduce invasive species that threaten native marine life. Scientific studies show that these artificial reefs can do more harm than good—Alaska deserves better than becoming a dumping ground for obsolete oil rigs.

Rigs-to-reefs isn’t about conservation; it’s about letting oil companies off the hook. These schemes leave decaying structures in the water, push the costs and risks onto local communities, and create new problems by hosting invasive species.

Sure, some marine life uses underwater structures, but offshore platforms mostly attract invasive species and were never meant to support healthy ecosystems. These platforms can actually help harmful species spread into vulnerable areas. Removing old oil and gas structures lets us restore the seafloor, make room for real conservation and renewable energy projects, and deliver lasting benefits for both the environment and our economy.

​Sens. Schiff and Padilla recently introduced a viable alternative: the “Offshore Leasing Standards and Accountability Act.” Representative Min (D-CA) is leading the House companion, H.R. 9034, along with 17 cosponsors. This legislation would amend the Outer Continental Shelf Lands Act by increasing regulatory oversight of offshore oil and gas operators through the implementation of fitness-to-operate standards, routine compliance reviews, and stricter limitations on temporary well abandonment. By mandating decommissioning escrow accounts and formalizing financial assurance requirements, the act ensures that oil and gas companies, rather than taxpayers, are financially responsible for site cleanup. Overall, these measures are intended to reduce the risk of abandoned infrastructure and shift the financial burden of decommissioning from the public to private operators.

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