The Obama administration, citing rigorous safety standards and a long review process, has granted conditional approval to energy giant Shell to begin oil drilling in the Arctic waters off the coast of Alaska.

The Interior Department wrote in a statement Monday that Shell could begin drilling in the Chukchi Sea once several environmental conditions are met, including a sign-off from agencies assessing the impact on endangered species.

The Bureau of Ocean Energy Management's director, Abigail Ross Hopper, said in a statement that officials recognize "the significant environmental, social and ecological resources in the region" and have established "high standards for the protection of this critical ecosystem, our Arctic communities, and the subsistence needs and cultural traditions of Alaska Natives."

"As we move forward, any offshore exploratory activities will continue to be subject to rigorous safety standards," she said.

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The Port of Seattle would need to get another permit to base the Arctic drilling fleet in Seattle for about six months of the year.

Activists plan to protest. A so-called "festival of resistance" starts Saturday and will include protesters on land and in kayaks, trying to block the ship's movements.

Environmental groups on Monday blasted the Bureau of Ocean Energy Management for providing the permit to Shell.

"This decision places big oil before people, putting the Arctic's iconic wildlife and the health of our planet on the line," Erik Grafe, an attorney for Earthjustice, said in a statement. "The agency should not be approving such threatening plans based on a rushed and incomplete environmental and safety review. Ultimately, Arctic Ocean drilling is far too risky and undermines the administration's efforts to address climate change and transition to a clean energy future."

Shell's drilling plan proposes to drill up to six wells within the Burger Prospect, located about 70 miles northwest of the village of Wainwright, Alaska. The wells would be drilled in about 140 feet of water by the Polar Pioneer and the Noble Discoverer. Both vessels would provide relief-well capability for the other.

Shell has said the two ships will leave the Chukchi Sea at the end of each drilling season.

Arctic offshore reserves are estimated at 26 billion barrels of recoverable oil and 130 trillion cubic feet of natural gas, according to U.S. Geological Survey estimates.

MORE ON WEATHER.COM: Alaskan Glaciers

Muir Glacier and Inlet (1895)

In the photo above, the west shoreline of Muir Inlet in Alaska's Glacier Bay National Park & Preserve is shown as it appeared in 1895. Notice the lack of vegetation on the slopes of the mountains, and the glacier that stands more than 300 feet high. See the glacier as it looked in 2005 on the next page. (USGS/Bruce Molnia)