In a May 1962 photo, Stewart Udall, right, strolls a path with legendary American poet Robert Frost. The two were brought together during a 100th anniversary gathering marking the death of Henry David Thoreau. STEWART UDALL PHOTO COLLECTION

Stewart L. Udall, the first Arizonan appointed to the Cabinet and a towering figure in environmentalism for more than 50 years, died of natural causes Saturday.

The former Democratic congressman was 90.

Said President Obama: "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."

Udall died at his home in Santa Fe, N.M., surrounded by family, according to a statement from his family, released through the office of his son, Sen. Tom Udall.

He had been in bed since a fall last week.

Udall served as interior secretary under Presidents Kennedy and Johnson during the 1960s. He was the last surviving member of Kennedy's original Cabinet.

He also represented Southern Arizona in the House of Representatives in the 1950s.

Udall worked with his late brother, former Rep. Morris K. Udall, on countless environmental and Native American initiatives.

Some of the accomplishments from Udall's Cabinet career included the creation of the Wilderness Act of 1964, The Wild and Scenic Rivers Act and the expansion of the National Park system. He also helped create The Land and Conservation Fund.

Udall oversaw the formal creation of four parks, six national monuments, eight seashores and lakeshores, nine recreation areas, 20 historic sites and 56 wildlife refuges, according to Star archives.

Udall was born in St. Johns, a town founded by his grandfather, a Mormon missionary. Udall's father, Levi S. Udall, served as an Arizona Supreme Court justice.

Stewart Udall served as an Army Air Forces gunner in World War II, flying 50 missions over Western Europe and receiving the Air Medal with three Oak Leaf Clusters.

He graduated from the University of Arizona, where he earned undergraduate and law degrees. He took a break from his studies to do missionary work for the Mormon church on the East Coast.

"Stewart Udall was one of our most distinguished and accomplished alumni," said Lawrence Ponoroff, dean of the UA's James E. Rogers College of Law in a prepared statement. "He served as a source of inspiration for countless lawyers and law students, and he will be greatly missed."

Udall started as a Tucson attorney who fought to desegregate the city's schools, open UA eating facilities to blacks and help pass a law banning discrimination against minorities in hiring.

In 1968, he and his brother pushed through a bill creating the Central Arizona Project, which was signed by President Johnson.

As a private attorney in the 1970s and '80s, he won a 30-year battle to get Navajo uranium miners compensated for lung cancer incurred on the job.

He also wrote "The Quiet Crisis" in 1963, a landmark book offering an early warning on threats to the environment.

"Stewart Udall was, plainly and simply, the most consistent, most respected and most effective American environmental voice of the past 50 years," said Rep. Gabrielle Giffords, D-Ariz. "What he did beginning five decades ago as secretary of the interior shaped the nation we are today."

In October, President Obama signed a bill renaming a Tucson-based organization that once only carried his brother's name. The group is now known as the Morris K. Udall and Stewart L. Udall Foundation.

Established by Congress in 1992, the foundation provides scholarships to college students who intend to pursue environmental careers and Native American students pursuing tribal policy or health care careers.

Udall is survived by his son Tom and five other children.

He's also survived by his nephew, Sen. Mark Udall of Colorado.

A memorial will be held later this year in Santa Fe, according to the family's statement.

Contributions in Udall's memory can be made to the following organizations: Santa Fe Pro Musica, Santa Fe Conservation Trust and Think New Mexico.

Udall remembered

Reactions to the death of former Interior Secretary Stewart Udall

"As a member of President Kennedy's Cabinet, he set the standard for commitment to conservation and stewardship of public lands."

- Sen. Jeff Bingaman, D-N.M.

"Stewart Udall was a giant in conservation and the father of America's wilderness and national park system. The Udall family, led by Stewart, symbolized a new environmentally conscious West."

- New Mexico Gov. Bill Richardson

"He was a true statesman, a role model for anyone who believes in the honor and privilege of public service and for those who champion our environment." - Rep. Harry Mitchell, D-Ariz.

The Associated Press contributed to this story. Contact reporter Jamar Younger at 573-4115 or