The U.S. Coast Guard is warning mariners in Cook Inlet to take caution while passing the area of a reported gas leak after a federal agency determined the risk of an explosion or fire from the leaking gas to be low.
The leak was discovered after a Hilcorp helicopter spotted what the company described as "bubbling" water over the pipe route.
The head of a watchdog group said on Tuesday he believes the size of the leak is larger than Hilcorp Alaska has suggested by its "bubbling" reference.
"It's not some tiny bubbles percolating to the surface," said Bob Shavelson, executive director of Cook Inletkeeper. "If you ran a vessel over that, you'd think it was a roiling cauldron."
The production platform, named "Platform A," is located about 5 miles offshore, northwest of Kenai. A Coast Guard official said the leak is about 3½ miles off shore.
The National Oceanic and Atmospheric Administration is worried about the risk to wildlife, an official said Tuesday.
"We are concerned this incident could have adverse impacts to marine life, particularly marine mammals," said Julie Speegle, a communications officer with NOAA's National Marine Fisheries Service in Alaska. "Our greatest concern is for endangered Cook Inlet beluga whales and impacts to their critical habitat."
Speegle said NOAA Fisheries is working with state and federal agencies to provide input on the leak.
The risk that the gas will ignite is "small," said Catherine Berg, with the Emergency Response Division for NOAA.
She did a flammability assessment on Thursday at the Coast Guard's request, she said.
She said such information would help determine the danger to a boat, say, if divers were sent to the area to respond to the leak. That is in fact something Hilcorp plans to do.
The Coast Guard had requested an analysis of a leak between 300,000 and 400,000 cubic feet of gas per day. Berg said she ran the highest amount through a model to come up with her assessment.
The size of the leak is estimated to be smaller. A spokesperson with the Alaska Department of Environmental Conservation said in an email Tuesday afternoon the leak rate is estimated at between 225,000 to 325,000 cubic feet of gas per day.
The leak falls into something of a regulatory gray area as far as pollution is concerned.
The DEC does not regulate natural gas, only liquid products. The U.S. Coast Guard also does not regulate natural gas for pollution purposes, unless it leaves a sheen on the water, said Lt. Brent Mellen, head of the Coast Guard detachment in Homer.
The Hilcorp gas leak is not accompanied by a sheen, he said.
The Coast Guard is responsible for making sure the water is safe for vessel traffic, Mellen said, leading to the reports warning mariners to be cautious in the area of the leak. The reports are repeated regularly on marine band radio.
Because of pans of ice and winter conditions, boats near the area are limited to ice-management and tanker vessels.
"We keep in contact with pilots and we are tracking those very closely," he said.
Shavelson, with Cook Inletkeeper, asked state regulators in a letter sent Friday to shut down the leaking pipeline until repairs are made.
Lori Nelson, external affairs manager at Hilcorp Alaska, said the company is monitoring ice conditions and will dispatch divers when it can be done safely.
"The safety of our people and the environment remains our priority as we work with the proper authorities on how to best manage this situation," she said in an emailed statement on Tuesday.
A story about the leak published last week in Alaska Dispatch News said the pipeline carried gas to shore. But on Tuesday, Nelson described the pipeline as a fuel line that carried natural gas from shore to Platform A and nearby Platform C.
It "provides for the safe operation of both platforms and shutting in the line would put it at risk of taking in water, freezing and potentially rupturing," she said.
DEC said there are "significant issues" with shutting down the pipe, including safety issues for platform crews.
Correction: This story originally said the Alaska Department of Environmental Conservation had not provided information about the size of the spill or issues that could be associated with shutting down the pipeline. In fact, DEC had sent an email Tuesday afternoon addressing those questions.