SANTA FE, N.M. -- Stewart Udall, who sowed the seeds of the modern environmental movement as secretary of the interior during the 1960s and later became a crusader for victims of radiation exposure from the government's Cold War nuclear programs, died Saturday. He was 90.
A statement from Udall's family, released through the office of his son, Sen. Tom Udall, D-N.M., said he died of natural causes at his home in Santa Fe, surrounded by his children and their families.
Udall, brother of the late 15-term congressman Morris Udall, served six years in Congress as a Democrat from Arizona, and then headed the Interior Department for eight years under Presidents Kennedy and Johnson. His son Tom and nephew Mark also became congressmen, then both were elected to the Senate in 2008.
Under Stewart Udall's leadership from 1961 through 1968, the Interior Department aggressively promoted an expansion of public lands and helped win enactment of major environmental laws, including ones to protect endangered species.
President Obama praised Udall's service.
"Whether in the skies above Italy in World War II, in Congress or as secretary of the Interior, Stewart Udall left an indelible mark on this nation and inspired countless Americans who will continue his fight for clean air, clean water and to maintain our many natural treasures," he said.
The current Interior secretary, Ken Salazar, called Udall "one of the greatest secretaries of the Interior in my lifetime."
He "was a pioneer and a visionary in protecting America's natural resources and cultural heritage who exemplified his family's commitment to public service," Salazar said. "Stewart Udall will be greatly missed."
Udall helped write several of the most far-reaching pieces of legislation, including the Wilderness Act of 1964, which protects millions of acres from logging, mining and other development.
"I never lost an argument with the budget people under either Kennedy or Johnson. If you had a new national park or a new policy on wilderness or something on wild rivers ... they'd say, 'Go ahead. It's a good idea,'" Udall once said in an interview.
More than 60 additions were made to the National Park system during the Udall years, including Canyonlands National Park in Utah, North Cascades National Park in Washington, Redwood National Park in California and the Appalachian National Scenic Trail stretching from Georgia to Maine.
In a 1963 book, Udall warned of a "quiet conservation crisis" from pollution, overuse of natural resources and dwindling open spaces. He appealed for a new "land conscience" to preserve the environment.
"If in our haste to 'progress,' the economics of ecology are disregarded by citizens and policy makers alike, the result will be an ugly America," Udall wrote. "We cannot afford an America where expedience tramples upon esthetics and development decisions are made with an eye only on the present."
After leaving government service, Udall taught, practiced law and wrote books. In 1979, he left Washington to return home to Arizona. In doing so, Udall began another career - leading a legal battle against the government he had once served as an influential insider.
Udall helped bring a lawsuit against the government on behalf of the families of Navajo men who suffered lung cancer in mining uranium for the government. Another lawsuit sought compensation for people who lived downwind from aboveground nuclear tests in Nevada during the 1950s and early 1960s.