


There are an estimated 340 beluga whales in the Cook Inlet of Alaska, where scientists worry an underwater leak of natural gas may be threatening their habitat. The whales were listed as endangered in 2008. Credit: Barry Williams/Getty Images






Cook Inlet, Alaska habitat for beluga whales

The company that owns the 52-year-old pipeline, Hilcorp Alaska, says the pipeline can't be shut down without risking further environmental damage, and it won't be able to begin to fix it until the ice melts in late March or April. Ice in the inlet isn't a solid sheet, but is in large, floating chunks that are constantly moving and changing, in part due to the tides in Cook Inlet, which are among the highest in the world. The tides can be as high as 35 feet, making it too risky to send divers into the water. The delay raises concerns about long-term repercussions.  

"There are three potential impacts that we worry about," said Sabine, who directs NOAA's Pacific Marine Environmental Laboratory in Seattle.

The first is what happens to fish when they are exposed to methane, he said.

The gas is bubbling out of the pipeline 80 feet below the surface and making its way up, but not all of it makes it to the top. In any underwater pipeline leak, some of the gas will disperse along the way, Sabine said. In this case, the gas contained in the plume happens to be particularly potent. "Those high concentrations of methane can have direct impacts on any organisms that might come in contact with water that's supersaturated with methane," he said.

How fish react to methane exposure is not well studied, but the research that does exist points to potentially dire impacts. Russian toxicologist Stanislav Patin studied fish and methane in his 1999 book, "Environmental Impact of the Offshore Oil and Gas Industry," which took an in-depth look at the issue. In one section that has been translated, he cites studies of two gas blowouts in the Sea of Azov in the 1980s, lab experiments in Russia and work in the North Sea, Black Sea and Sea of Okhotsk to show that the impacts can be nearly immediate.

"Gas rapidly penetrates into the organism (especially through the gills) and disturbs the main functional systems (respiration, nervous system, blood formation, enzyme activity, and others)," Patin wrote.

Two other potential problems loom, Sabine said. As methane diffuses in water, bacteria metabolize it, using oxygen from the water and producing additional carbon dioxide in the process. This can deplete the oxygen levels in the water, creating a hypoxic zone, which Patin also addressed in his paper. "Numerous studies show that the oxygen deficit directly controls the rate of fish metabolism and decreases their resistance to many organic and inorganic poisons," Patin wrote.

At the same time, the extra CO2 created by the bacteria can cause the the water to become more acidic, which can have impacts like weakening the shells of some species.

What it Means for the Belugas

Sadie Wright, a NOAA marine mammals specialist who is leading the agency's response to the leak, said the creation of a hypoxic zone is the biggest concern.

There are an estimated 340 belugas in Cook Inlet. In 2008, they were listed as endangered under the Endangered Species Act and three years later, the National Marine Fisheries Service designated some areas of the inlet, including the location of the gas leak, as critical habitat. That designation is based on the presence of what NOAA calls "PBFs"—or physical and biological features essential for conservation of the species. Some of those characteristics could be at risk now.

"We think multiple PBFs could potentially be impacted," Wright said, in particular the belugas' prey, their ability to travel undisturbed within its critical habitat, and quiet waters.

"We don't have any idea how loud the leak might be," said Wright. "That's a potential stressor." According to a letter sent from NOAA to Chris Hoidal of the Pipeline and Hazardous Materials Safety Administration, excessive noise can cause belugas to abandon their critical habitat.

They also don't know how the beluga's prey might be impacted, because no measurements have been taken of oxygen or methane levels in the water.

Wright said NOAA has information about how much oxygen must be present in water to support the beluga's prey. But without monitoring the water, there's no way to know whether those thresholds are being reached.

Since the leak was first reported on Feb. 7, it has been nearly impossible to assess what's going on, according to the company and the state and federal agencies working on the response. Many days, even a helicopter flight over the leak is out of the question due to inclement weather.

"It's just a very difficult environment, particularly in the winter," said Barbara Mahoney, a NOAA biologist who specializes in the Cook Inlet beluga whales. "When there's ice, there's no room for mistakes."

Ice also could be exacerbating the methane problem.

When underwater natural gas pipelines leak, the gas can typically bubble up in a plume to the water's surface and then escape into the atmosphere (which comes with its own problems, because methane is 20 times as potent as carbon dioxide as a greenhouse gas). But in this case, the gas cannot escape freely.

The impact of ice cover on a natural gas leak hasn't been well researched. But those who study natural gas leaks say the ice would certainly change the flow of methane.

"That might actually prevent the methane from going into the atmosphere," said Jan Erik Olsen, a petroleum engineer who has studied bubble plumes at Sintef, an independent Norwegian research organization. "That would cause a buildup of methane concentration in the water."

Why Cook Inlet Is a Perfect Storm

Cook Inlet splinters off from the Gulf of Alaska, spanning 180 miles to Anchorage in southwestern Alaska. The inlet becomes increasingly narrow at its northern end. Near the town of Nikiski, about halfway up, land juts out into the inlet from both sides, making it even narrower. That is where the leak is located.

"This break unfortunately is about halfway up the estuary in a pinched zone," said Sabine. "All the water has to flow right past that, so it's conceivable that you're contaminating a significant fraction of the water in the whole estuary."

Between the high tides and the strong currents, there is a large amount of water moving quickly past the leak. In theory, the large flow of water could help minimize the impacts of the gas by diluting it. But it also means more water ultimately gets exposed to the methane.

"It's a question of how quickly the concentrations are being diluted, and at what levels will they still impact the marine ecosystems," said Sabine. "That's where we don't know enough yet."

Last week, Hilcorp submitted a draft plan to the state Department of Environmental Conservation for monitoring the leak and its environmental impacts, which is currently being reviewed. Until it is accepted and implemented, the impacts of the leak will continue to go unmonitored.

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