The environmental protection movement in Idaho dates from 1897, when President Grover Cleveland established the Bitterroot Forest Preserve, encompassing much of the northern region. In the early 1930s, the US Forest Service set aside some 3 million acres (1.2 million hectares) of Idaho's roadless forestland as primitive areas. The Taylor Grazing Act of 1934 regulated grazing on public lands, providing for the first time some relief from the overgrazing that had transformed much of Idaho's grassland into sagebrush desert. Thirty years later, Idaho Senator Frank Church was floor sponsor for the bill creating the National Wilderness System, which now contains most of the primitive areas set aside earlier. Many miles of Idaho streams are now in the Wild and Scenic Rivers System, another congressional accomplishment in which Senator Church played a leading role. In 1970, Governor Cecil Andrus (later, US secretary of the interior) was elected partly on a platform of environmental protection. On 17 January 2001 the site near Jerome of a World War II camp where Japanese Americans were interned became Minidoka Internment National Monument; the National Park Service began planning for visitor facilities there in 2002.
The Department of Health and Welfare's Division of Environment is responsible for enforcing environmental standards. Air quality improved greatly between 1978 and 1997, following the passage of federal regulations strengthening the Clean Air Act. Vehicle emissions were responsible for high carbon monoxide levels in the Boise area in the late 1970s and 1980s. Emissions have dropped to the point that no carbon monoxide violations have occurred for several years.
Water quality is generally good. Most of the existing problems stem from runoff from agricultural lands. Water quality is rated as only fair in the Upper Snake River Basin and in the Southwest Basin around Boise, and as poor in the Bear River Basin, partly because of municipal effluents from Soda Springs and Preston. The state has 386,000 acres of wetlands. The Idaho Department of Fish and Game has implemented plans to acquire privately owned wetlands deemed to be in danger. The plan runs from 1991 to 2005.
Since 1953, nuclear waste has been buried at the Idaho National Engineering Laboratory west of Idaho Falls or discharged in liquid form into the underground aquifer; some isotopes are migrating toward the boundaries of the site. Tailings from a former uranium-ore milling operation near Lowman are a potential health hazard. A top-priority site for hazardous-waste cleanup is Bunker Hill Mining at Smelterville; two sites in Pocatello are also considered candidates for cleanup. In 2003, the Environmental Protection Agency's database listed 87 hazardous waste sites, 6 of which were on the National Priorities List, in Idaho. In 2001, Idaho received $32,577,000 in federal grants from the EPA; EPA expenditures for procurement contracts in Idaho that year amounted to $100,000.