Underwater pipeline has been leaking gas into a beluga whale habitat for 3 months

An underwater natural gas pipeline has been leaking for three months into an endangered beluga whale habitat.

The mud flats of Cook Inlet, just off the shore of Anchorage, Alaska. CREDIT: AP Photo/Mark Thiessen, File
The mud flats of Cook Inlet, just off the shore of Anchorage, Alaska. CREDIT: AP Photo/Mark Thiessen, File

Alaska’s Cook Inlet has long been known for its stunning mountain views and the endangered beluga whales that inhabit the watershed. But a series of oil and gas leaks from underwater pipelines, one of which is still ongoing, has residents and environmentalists concerned both about the short-term impacts on sensitive wildlife and the long-term risks of the region’s aging pipeline infrastructure.

“It’s a radical physical environment for steel infrastructure,” Bob Shavelson, advocacy director at the Cook Inlet-based Inletkeeper, told ThinkProgress. The southern Alaska inlet contains more than 1,000 miles of pipelines and 16 offshore oil and gas platforms, frequently operating in harsh conditions, including earthquakes and three feet of ice.

In early February, officials with pipeline company Hilcorp Alaska reported that natural gas was leaking into Cook Inlet from an eight-inch pipeline used to transport gas to offshore oil drilling platforms. Later, it was determined that the leak started months earlier, in December, and was sending 210,000 to 310,000 cubic feet of natural gas into the watershed every day.

The ongoing leak — from a pipeline that, according to Inletkeeper, leaked twice in 2014 — highlights the need for increased attention to the region’s pipelines. Shavelson said his group wants a “comprehensive risk assessment” of the energy infrastructure of Cook Inlet and a review of the financial risks associated with pipelines in the inlet, about 275 miles of which are 40 to 50 years old.


In 2002, Inletkeeper published a report on the incidence of spills from the watershed’s oil and gas pipelines. It found that, in the five-year period between 1997 and 2001, pipeline spills were reported in Cook Inlet once a month on average, and that onshore pipelines leaked more frequently than offshore. In order to bring down the number of spills, Inletkeeper says, the region needs an “independent audit” of pipeline infrastructure.

The Center for Biological Diversity agrees. The environmental group announced a legal petition last week asking federal and Alaska regulators to perform an inspection on all offshore pipelines in Cook Inlet. The pipelines in the inlet, CBD claims, are “some of the oldest in the country,” and since risk for failure goes up once pipelines hit the age of 30, the region’s pipelines are overdue for an assessment. Hilcorp inspects the pipelines annually, but these sort of inspections don’t determine whether the pipelines have become eroded or dented, according to InsideClimate News.

“It’s scary to think about how decayed some of the offshore pipelines littering Cook Inlet may be,” Kristen Monsell, an attorney for CBD, said in a statement. “These old, vulnerable pipelines pose a toxic threat to the people and wildlife of Cook Inlet.”

“These old, vulnerable pipelines pose a toxic threat to the people and wildlife of Cook Inlet.”

The pipelines in Cook Inlet are subject to “unforgiving natural forces” of the inlet, including extremely high tides, Shavelson said. But underwater pipelines aren’t inherently more prone to leaking than above-ground pipelines, according to Rebecca Craven, program director at Pipeline Safety Trust. The risks are different between a leak in Cook Inlet and a leak in downtown Anchorage, she said, and the consequences of a failure are also different.


Across the country, offshore natural gas transmission pipelines leaked — or experienced another sort of “incident” — an average of 16 times a year between 2007 and 2016, according to data from the Pipeline and Hazardous Materials Safety Administration (PHMSA). The number for onshore natural gas transmission pipelines is higher: these lines had an average of 98 incidents per year between 2007 and 2016. There’s also a lot more onshore natural gas pipeline in the U.S. than offshore — 297,343 miles of onshore pipeline in 2015, compared to 3,833 miles of offshore.

“One of the triggers for us is the causes of incidents over time,” Craven said. Two of the largest causes of incidents, according to PHMSA, are corrosion and equipment failure. “Those are incidents that have occurred that are within the control of the operator. This is not third-party people digging into a pipeline and causing incidents.”

So the total number of incidents needs to decrease, and the number of incidents caused by these avoidable problems also needs to go down, she said. That requires more attention to detail on the part of pipeline operators — both before the pipeline goes into service, and after.

The ongoing leak is just one of Hilcorp’s recent troubles in Cook Inlet, however. Earlier this month, the company discovered an oil leak in one of its underwater pipelines in the region. The leak, which is not related to the ongoing natural gas leak, was stopped soon after “six sheens” were discovered by the state Department of Environmental Conservation (DEC). Then, over the weekend, another release of natural gas was reported in the inlet from another Hilcorp pipeline.


Hilcorp maintains that the incident was a “metering anomaly,” not a leak, but Alaska’s DEC told InsideClimate News that, to the best of their knowledge, the incident can be characterized as a leak. It’s unclear so far how much gas may have escaped from the third pipeline incident, but Hilcorp removed all natural gas from the line in order to prevent further leakage and says it will investigate the incident.


These incidents have drawn the ire of environmental groups, but how severely the leaks will impact the environment — and the inlet’s approximately 340 endangered beluga whales — remains to be seen.

Natural gas consists primarily of methane. The DEC considers methane a “hazardous substance,” and there is concern that the methane leaking into the inlet could create low-oxygen areas in the inlet, which could negatively impact the belugas, fish and other wildlife that lives there. The National Oceanic and Atmospheric Administration (NOAA) has also raised noise levels and harm to the belugas’ prey as potential cause for concern. The DEC, meanwhile, sent a letter to Hilcorp on February 27, saying it was crucial that the company set up an acoustic monitoring system and a wildlife monitoring system in the area affected by the leak.

The first water tests taken by the company in late March showed dangerously high methane levels in the inlet. Shavelson said he wishes he knew more about the risks the ongoing leak poses to fish, migratory birds, and the inlet’s population of beluga whales.

“There hasn’t been a lot of peer-reviewed scientific literature on the impacts of methane, particularly in the water,” Shavelson told ThinkProgress. But, he said, “it’s a hydrocarbon. We know it’s going to have some adverse effect, but it’s just another example of our inability to understand the impact humans have on our natural systems.”

“It’s just another example of our inability to understand the impact humans have on our natural systems.”

The cause of the initial, ongoing natural gas pipeline leak remains unclear. Until now, icy conditions have prevented Hilcorp from stopping the leak, but the company has reduced the pressure in the pipeline and shut down the oil platforms that are fed by the line. Over the weekend, as weather conditions began to warm in the inlet, Hilcorp sent divers down to inspect and begin work on repairing the pipeline, which they discovered had a leak point about 2 inches long. PHMSA has ordered Hilcorp to fix the leak or shut down the leaking pipeline by May 1, and also to inspect a “substantially similar” underwater oil pipeline in the region.

If Shavelson has his way, however, these won’t be the last actions taken on this pipeline infrastructure. He sent a letter to Alaska’s governor last week, urging him to order the comprehensive assessment of the region’s infrastructure that Inletkeeper believes is crucial to the future safety of the inlet.

Katie Valentine, a former ThinkProgress climate editor, is now a freelance contributor based in Toronto.