Shell’s plan to take up oil drilling again this summer in remote Arctic waters of the Chukchi Sea cleared a key hurdle on Monday, winning approval from the U.S. Bureau of Ocean Energy Management.

“As we move forward, any offshore exploratory activities will continue to be subject to rigorous safety standards,” the bureau’s director, Abigail Ross Harper, said in a statement.

“We have taken a thoughtful approach to carefully considering potential exploration in the Chukchi Sea, recognizing the significant environmental, social and ecological resources in the region and establishing high standards for the protection of this critical ecosystem, our Arctic communities and the subsistence needs and cultural traditions of Alaska natives,” she added.

Shell is returning to the scene of multiple mishaps three years ago.

The oil giant’s plans to have two rigs working in the Chukchi, at a site about 70 miles northwest of the Inupiat village of Wainwright. Shell’s two rigs will be drilling in about 140 feet of water, in an ocean that is covered with ice for much of the year. It will be drilling in what is known as the Burger Prospect.

Shell must still win approval from another U.S. Interior Department agency, the Bureau of Safety and Environmental Enforcement. It must also obtain permits under the Marine Mammal Protection Act.

The Chukchi Sea is a summer feeding ground for gray whales, which migrate up the Pacific Coast each spring. It is a major habitat for bowhead whales.

An estimated 2,000 polar bears — 10 percent of the world’s population — make their home on ice floes in the Chukchi, feeding off seals. The bears have been listed under the Endangered Species Act due to the threat that global warming poses to their habitat.

The federal decision set off a blizzard of newss release denunciations from environmental groups that oppose oil exploration in the Arctic.

“Ultimately, Arctic Ocean drilling is far too risk and undermines the administration’s efforts to address climate change and transition to a clean energy future: These fossil fuels need to remain in the ground,” said Erik Grafe, staff attorney with Earthjustice.

Earthjustice, representing four environmental groups, has mounted a legal challenge to Shell’s Arctic drilling fillet using the Port of Seattle’s Terminal 5 as home port for its exploration bid.

David Yarnold, CEO of the National Audubon Society, added: “Spills under ice sheets can’t be controlled, and America doesn’t need the oil in order to maintain its energy independence. So this is just cynical partisan politics, a public relations bone that the Obama administration is throwing to Shell.”

Shell is hungry. The oil giant has invested an estimate $5.8 billion on leases and equipment to explore in the Arctic. It has put off other projects this year, but is going ahead with drilling in the Chukchi Sea.

Shell plans to have two drilling rigs, the Polar Pioneer and the Noble Discoverer, at work this summer. The goal is to drill as many as six exploratory wells.

The Nobel Discoverer was driven off by pack ice in 2012. The ship also broke loose from its anchor and nearly ran aground in Unalaska Sound. A Coast Guard inspection of the ship, late in the year, resulted in eight felony convictions against Shell’s subcontractor and $12.2 million in fines.

The Polar Pioneer is taking the place of the Kulluk. The conical drilling ship broke its tug lines while crossing the Gulf of Alaska in a winter storm. It ran aground and was wrecked.

The Shell plan for 2015 will have each of the two ships, Polar Pioneer and Noble Discoverer, serve as the other’s backup. Each will be able to drill a blowout well if it is needed.

Under BOEM rules, Shell must have a contingency plan in place to drill a relief well prior to the return of winter pack ice. Shell will be required to stop the 2015 drilling on Sept. 28 if the two rigs are working together. If one rig has returned to Dutch Harbor, drilling must cease on Sept. 24.

Curtis Smith, a spokesman for Shell, said the BOEM approval “signals the confidence regulators have in our plans.” But, he added, “It’s imperative that the remainder of our permits be practical, and delivered in a timely manner.”

“In the meantime,” said Smith, “we will continue to test and prepare our contractors, assets and contingency plans against the high bar stakeholders and regulators expect of an Arctic operator.”

On Saturday, hundreds of Seattle-area kayakers are expected to take to the waters of Elliott Bay for a sea-and-land protest against Shell’s Arctic drilling plans.

Alex Taurel of the League of Conservation Voters summed up the essence of opposition to Shell: “Drilling in undeveloped areas like the Arctic Ocean will mean locking in decades of new carbon pollution at a time when climate science tells us we need to move rapidly to clean energy sources.”