The Izaak Walton League of America (IWLA), nicknamed the "Waltonians," was named for a seventeenth-century English writer and angler. Fifty-four men formed the League in Chicago in January 1922, and by 1928 the organization had 175,000 members in 3,000 chapters in 40 states.

Local civic leaders, conservationists, and other men formed the Portland Chapter of the IWLA on December 15, 1922. The first elected officers included Noyes E. Tyrrell, a 1903 charter member of the Multnomah Anglers' Club, and state Senator John Gill. The executive committee included naturalist William L. Finley, Mazamas mountaineering club president John A. Lee, and noted conservationist and newspaper editor Marshall N. Dana.

IWLA members combined practical conservation goals with spiritual reverence to sustain outdoor recreational opportunities threatened by industrialization and urbanization. National and state IWLA leaders translated these motivations to lobby policy makers and educate the public.

Sportsmen's groups had been a feature of American society since the mid-nineteenth century, but membership in organized hunting and fishing clubs increased markedly by the first decades of the twentieth century. This growing interest reflected a more democratic access to outdoor recreational opportunities as well as increased leisure time, which fostered a shift in the relationship between Americans and their environment. Rather than conceiving of the environment solely in terms of resource extraction, the experience of the environment in itself became important.

In Oregon, both the Portland Chapter and the Oregon Division of the IWLA continued to grow throughout the 1920s and 1930s. By 1943, there were chapters throughout the state, including those in Portland, Tillamook, Marshfield, Silverton, Klamath Falls, and Astoria. The Portland Chapter had grown to "an all-time high" of 419 members by October 1959, and the state division membership numbered 1,761 that year.

Oregon IWLA members represented a broad spectrum of professions. In 1959, Portland Chapter members included municipal, state, and federal officials; professionals in the fields of medicine, law, finance, sales, education, food service, publishing, insurance, manufacturing, and the media; and representatives from timber and pulp and paper companies. Though membership in sportsmen's organizations was still largely male, women were members of the IWLA.

Interests of Oregon IWLA members illustrate the diversity of its membership and the organization's natural resources conservation approach. From the Portland Chapter's founding, members were at the forefront of water pollution abatement efforts. While many members welcomed the construction of irrigation and hydroelectric dams in the region, some also strongly opposed certain water impoundment proposals on the Columbia, Willamette, McKenzie, Deschutes, Rogue, and other rivers, particularly after World War II. Oregon IWLA committees were involved with conservation education, fishery and forestry practices, soil conservation, and public relations.

The Oregon IWLA followed the general Waltonian focus on pursuing achievable goals to balance natural resource preservation and development. David B. Charlton, an independent bacteriologist in Portland and a state and national IWLA leader, applied this perspective in his advocacy for Willamette River water pollution abatement from the 1930s to the early 1980s. Like other Waltonians, Charlton worked within the political, social, economic, and ideological realities of his time. Writing in November 1959, he asserted that he was "not one that believes that the Willamette River will ever be entirely ‘cleaned up.'" A "certain amount of industrial wastes" was unavoidable, he concluded, but he was confident that the river could be cleaned up enough that it would no longer pose health risks to people or fish.

IWLA members in Oregon and throughout the United States were at the forefront of environmental advocacy from the 1920s into the 1960s. By the early 1970s, however, leadership in citizen environmental activism had shifted to the Sierra Club, the National Resources Defense Council, the Audubon Society, and other groups. Nevertheless, the Oregon IWLA has continued to be involved in a wide array of conservation and education efforts. As of 2009, there were approximately 400 Oregon IWLA members in seven chapters.