If you've ever enjoyed a national park, hiked down a trail, backpacked into wilderness, or paddled a wild and scenic stream, pause and give a minute of thanks for Stewart L. Udall.

One of the most aggressive Interior secretaries of recent decades when it came to conserving landscapes as parks, monuments, wildlife refuges, national seashores, and wild and scenic rivers, Mr. Udall presided over a vibrant chapter of U.S. conservation during the 1960s. Along with seeing the establishment of Canyonlands, North Cascades, Redwood, and Guadalupe national parks, the Democrat whose roots ran deep in the Southwest helped shepherd The Wilderness Act, the National Wild and Scenic Rivers Act, the National Trails System Act, and the Endangered Species Act into the country's environmental consciousness.

When he passed away at his Santa Fe, New Mexico, home on March 20 at the age of 90, Mr. Udall's conservation ethics were once again thrust into the forefront of environmental activism as a symbol of what can be done with enough determination and desire. Though the late David Brower was unsuccessful in pleading with Secretary Udall not to plug the Colorado River with the Glen Canyon Dam, the secretary had so many achievements in land and water conservation that it's perhaps reasonable to forgive this failing.

As Thomas G. Smith noted in 1995 in John Kennedy, Stewart Udall, and New Frontier Conservation, the president and his Interior secretary approached the management of federal lands with a goal to provide "efficient resource use, public recreation, and the expansion of national parks," goals which the author noted Presidents Truman and Eisenhower had neglected.

"At the same time, they confronted an emerging ecological outlook that stressed wilderness preservation, environmental protection, and the interdependence of all parts of the natural world," Mr. Smith pointed out.

In approaching that mission, Secretary Udall corralled bipartisan support in Washington, something unheard of today.

"Stewart Udall’s adherence to bipartisanship to protect the environment serves as a dramatic contrast to the venomous partisanship that today characterizes the House and Senate Republican leaders," Brent Blackwelder, president emeritus of the Friends of the Earth, noted in applauding his legacy. "Stewart and his brother Rep. Morris Udall (1922-1998) worked with the Republican leaders of their day to solve problems and together, the bipartisan combination set milestones in conserving land, water, and wildlife."

One of the West's foremost political dynasties, the Udalls -- patriarch Levi, who served as chief justice of the Arizona Supreme Court; younger brother Morris, who also served in Congress and ran unsuccessfully for president and; son Tom, a U.S. senator from New Mexico -- grew up on the landscape that through the decades has been the focal point of opposing factions who thought they knew best how those lands should be stewarded. No doubt that familial history helped guide Stewart Udall's hand, both during his congressional tenure and his years as Interior secretary for Presidents Kennedy and Johnson. Though he was a champion of water projects, he also knew when land should be preserved just as it is.

"I had no idea anything like that existed there," he was said to remark in the early 1960s when he was flown over a southeastern Utah landscape that was being eyed for a dam along the Colorado River. "God almighty, that's a national park."

And under Secretary Udall it became one -- Canyonlands National Park.

Canyonlands was just one part of Secretary Udall's legacy. During his time in Washington he:

* Oversaw the addition of four parks, six national monuments, eight seashores and lakeshores, nine recreation areas, 20 historic sites and 56 wildlife refuges....

* Saw President Johnson sign into law the Wilderness Act, the Water Quality Act, the Wild and Scenic Rivers Act and National Trails Bill.

* Helped spark a cultural renaissance in America by setting in motion initiatives that led to the Kennedy Center, Wolf Trap Farm Park, the National Endowments for Arts and the Humanities, and the revived Ford’s Theatre.

* And was a recipient of the Ansel Adams Award, the Wilderness Society’s highest conservation award, and the United Nations Gold Medal for Lifetime Achievement.

Among the units of the National Park System he helped create, in addition to those mentioned above, were Assateague Island National Seashore, Cape Lookout National Seashore, Indiana Dunes and Pictured Rocks national lakeshores, the Hubbell Trading Post National Historic Site, and Padre Island National Seashore.

At the Coalition of National Park Service Retirees, Rick Smith, who chairs the group's executive council, worked for three "distinguished (Interior) secretaries--Udall, (Rogers) Morton, and (Cecil) Andrus."

"His book, The Quiet Crisis, shaped a lot of my thinking about the environmental issues of the time," Mr. Smith said.

"The members of the Coalition of National Park Service Retirees mourn the death of Stewart Udall," he added. "Many of us worked during the time that he was secretary of the Interior. We remember him not only for being the champion of the establishment of many additions to the National Park System, but also as the energy behind the enactment of many of our nation's most important environmental laws, including the Wilderness Act, the Endangered Species Act, the National Trails Act, the Wild and Scenic Rivers Act, and the Land and Water Conservation Act.

"We also appreciated the fact that he was not a secretary isolated in his D.C. office. He got out and did things. His raft trips on the Colorado through Grand Canyon helped save the canyon from dams," continued Mr. Smith. "He was not a stranger in parks. Many of us remember seeing him in the parks in which we worked. In later life, he became a conservation guru, often writing and speaking on behalf of the environment and historic preservation. His contributions were enormous, and like many Americans, we will miss his wise counsel."