The drill ship Kulluk is towed by the tugs Aiviq and Nanuq. Photograph: AP

Fulfilling dire predictions by environmentalists and conservationists that oil exploration and extraction in the Arctic was fought with peril, a Royal Dutch Shell offshore drilling rig carrying roughly 150,000 gallons of oil ran aground on an island in the Gulf of Alaska on Monday night threatening the pristine waters with a potential spill.

The rig, the Kulluk—one of two rigs that Shell used to drill test wells off the North Slope of Alaska as part of the company’s dangerous and costly effort to open Arctic waters to oil production—wrenched free from tow ships by fierce arctic swells and gale force winds.

The incident is the latest and most striking example yet proving concerns over the ill-preparedness of oil companies and the incredible risks of Arctic drilling are well-founded.

The ship is carrying about 139,000 gallons of diesel fuel and 12,000 gallons of lubricating oil and hydraulic fluid, officials said.

The New York Times reports:

A Coast Guard helicopter flew over the rig after the grounding at 8:48 p.m. and “detected no visible sheen,” said Darci Sinclair, a spokeswoman for a unified command of officials from Shell, Alaskan state agencies and other groups that has been directing the response since the troubles with the rig began last Thursday.

Ms. Sinclair said that more overflights were planned after daybreak on Tuesday, and that the unified command would be monitoring the fuel situation as it planned further actions.

“We are now entering into the salvage and possible spill-response phase of this event,” coastguard commander Shane Montoya said in a news conference late on Monday night in Anchorage.

The grounding of the Kulluk is the latest in a series of blunders by Shell, who has spent six years and over $4 billion in its effort to convert the the region into a major new oil frontier.

Critics and environmental groups have long warned that drilling in Arctic waters is a “dangerous, high-risk enterprise” with a potentially “catastrophic impact on one of the most pristine, unique and beautiful landscapes on earth.”

Greenpeace specifically cautioned, “The risks of such an accident are ever present and the oil industry’s response plans remain wholly inadequate.”

“Shell and its contractors are no match for Alaska’s weather and sea conditions either during drilling operations or during transit,” Lois Epstein, Alaska program director for the Wilderness Society, wrote in an email.

“Shell’s costly drilling experiment in the Arctic Ocean needs to be stopped by the federal government or by Shell itself given the unacceptably high risks it poses to both humans and the environment.”

Earlier Monday, a Shell spokesman had claimed that the rig had been brought under control after towlines were reconnected to two ships during a temporary lull in what had been several days of 30 foot swells and 65 mile an hour winds.

The final towline failure was the fifth time the lines had been resecured and lost since the incident began on Thursday.

The Anchorage Daily News reports:

[The Kulluk] broke loose from a Shell-contracted ship, the Aiviq, around 4:40 p.m. Monday. Then around 8:15 p.m., with the grounding imminent, the second tow boat, a borrowed tug named the Alert, was directed to lose its tow line to avoid danger to the nine crew members aboard, according to the command team managing the crisis, which also includes the Coast Guard, the state of Alaska and contractors.

In September, Shell Oil had to prematurely halt its drilling operation in the Arctic waters off the coast of Alaska after the failure of an oil spill containment dome on one of its ships.

At the time, Greenpeace made a statement that continues to ring true after Monday’s accident:

We can now see what a monumentally reckless gamble this was. The company has nothing to show for it except a series of almost farcical safety mishaps that has left its reputation in tatters. Investors must now be asking whether investing such vast sums of money trying to exploit the fragile Arctic is really worth it.