He backed up his words with deeds, gathering a bewildered constituency among the conservationists who had opposed him.

Soon after Mr. Hickel’s arrival in Washington, a Union Oil Company well blew out near Santa Barbara, Calif., spilling nearly 100,000 barrels of crude along the coast. He responded by issuing stricter offshore drilling regulations.

When a Chevron platform in the Gulf of Mexico caught fire in March 1970 and spewed more than 40,000 barrels, Mr. Hickel authorized an investigation. It found that Chevron had failed to install required safety devices on 90 wells. He pressed the Justice Department to file a suit charging 900 violations of the Outer Continental Shelf Lands Act of 1953.

At Mr. Hickel’s urging, suits were also filed against 10 companies accused of discharging mercury into interstate waters. And he led a successful campaign to halt construction of a mammoth jetport in the Everglades.

“Nobody in Washington,” Life magazine wrote of Mr. Hickel in August 1970, “seems to have come to so instant a realization that the environment is now as sacred as motherhood, and that the aspiring politico can belabor its violators not only without fear but with every expectation of deafening applause.”

Perhaps most surprising were Mr. Hickel’s efforts to delay approval of the trans-Alaska pipeline. As an Alaska “boomer” — a common term for the state’s pro-development forces — Mr. Hickel, in his first term as governor, had pushed for the construction of an 800-mile north-to-south oil pipeline from Prudhoe Bay on the Arctic coast to the ice-free port of Valdez on Prince William Sound near Anchorage.

He took over as interior secretary convinced that it was safe to build the pipeline. But soon afterward he listened to the concerns of geologists that it could despoil millions of acres of tundra unless the oil companies were required to make major safety alterations to their plans. With many of those changes in place, the pipeline was completed in 1977 and has since delivered more than 15 billion barrels of oil to the lower 48 states.