Salazar also approved the nation's first offshore wind farm, Cape Wind, off the Massachusetts coast.
On land, Salazar has promoted solar power in the West and Southwest, approving an unprecedented number of projects, even as oil and gas projects continued to be approved on federal land.
Salazar also oversaw a $3.4 billion settlement resolving a dispute with Native American tribes that had lingered for more than a decade.
Salazar was the fourth Interior secretary to consider a 1996 lawsuit by Elouise Cobell accusing the government of mismanaging land trust royalties for more than a century. But Salazar was the one who finally settled the case, said Jacqueline Pata, executive director of the National Congress of American Indians.
Salazar and Obama "made it very clear that one of the presidential campaign promises they were going to resolve was the Cobell lawsuit, and Salazar made it happen," Pata said.
Throughout his tenure, Salazar tangled with oil companies. He criticized the George W. Bush administration for what he called a "headlong rush" to lease public lands, saying officials treated oil and gas executives as if they were "the kings of the world." Soon after taking office, Salazar suspended 60 of 77 leases in Utah that had been approved under Bush, setting a confrontational tone that would continue the next four years.
Jim Noe, an oil executive and head of a shallow-water drilling coalition, said Wednesday that Salazar's actions "hurt the industry, thousands of workers and the small businesses and communities that depend upon them. We hope that future leadership at the Interior Department will be able to take a more balanced approach to natural resource development."
Frances Beinecke, president of the Natural Resources Defense Council, an environmental group, said Salazar worked to strike a balance between responsible energy development and vital environmental protection.
Salazar set a sound foundation for solar and wind power on federal lands, while protecting areas where development does not make sense, Beinecke said.
Sierra Club executive director Michael Brune hailed Salazar for opening seven new national parks and 10 wildlife refuges while protecting Arctic areas from offshore drilling.
Salazar's leadership "has helped put our nation on a path where protecting our natural legacy and wild lands is a priority, not an afterthought," Brune said.
Salazar is the second of Obama's two Hispanic Cabinet members to depart. Labor Secretary Hilda Solis said last week she is leaving.
Associated Press writers Julie Pace and Ken Thomas contributed to this report.
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