The Department of Natural Resources and the Department of Health share responsibility of state environmental programs. The first efforts to protect Colorado's natural resources were the result of federal initiatives. On 16 October 1891, US president Benjamin Harrison set aside the White River Plateau as the first forest reserve in the state. Eleven years later, President Theodore Roosevelt incorporated six areas in the Rockies as national forests. By 1906, 11 national forests covering about one-fourth of the state had been created. Mesa Verde National Park, founded in 1906, and Rocky Mountain National Park (1915) were placed under the direct control of the National Park Service. In 1978, Colorado became the first state in the US to encourage taxpayers to allocate part of their state income tax refunds to wildlife conservation. In addition, a state lottery was approved in the late 1980s, with proceeds approved for Great Outdoors Colorado (GOCO) to be used for parks improvement and wildlife and resource management.
Air pollution, water supply problems, and hazardous wastes head the list of Colorado's current environmental concerns. The Air Quality Control Commission, within the Department of Health, has primary responsibility for air pollution control. Because of high levels of carbon monoxide, nitrogen dioxide, and particulates in metropolitan Denver, Colorado Springs, Pueblo, and other cities, a motor vehicle emissions inspection system was inaugurated in January 1982 for gasoline-powered vehicles and in January 1985 for diesel-powered vehicles. The high altitudes of Colorado almost double auto emissions compared to auto emissions at sea level. The high level of particulates in the air is because of frequent temperature inversions along Colorado's Front Range. The state has launched an aggressive campaign to improve air quality. Cars must use oxygenated fuels, and pass tough vehicle emissions controls, and driving is discouraged on high pollution days.
Formal efforts to ensure the state's water supply date from the Newlands Reclamation Act of 1902, a federal program designed to promote irrigation projects in the semiarid plains areas; its first effort, the Uncompahgre Valley Project, reclaimed 146,000 acres (59,000 hectares) in Montrose and Delta counties. One of the largest undertakings, the Colorado–Big Thompson Project, started in the 1930s, diverts a huge amount of water from the Western to the Eastern Slope. Colorado's efforts to obtain water rights to the Vermejo River in the Rockies were halted in 1984 by the US Supreme Court, which ruled that New Mexico would retain these rights. Some 98% of Colorado's drinking water complies with federal and state standards. The Colorado Department of Health works with local officials to ensure federal standards for drinking water are met. Isolated aquifers are generally in good condition in Colorado, though a few are contaminated. Colorado's groundwater quality is generally high.
Colorado's rapid population growth during the 1970s and early 1980s taxed an already low water table, especially in the Denver metropolitan area. The Department of Natural Resources' Water Conservation Board and Division of Water Resources are responsible for addressing this and other water-related problems.
The Department of Health has primary responsibility for hazardous waste management. From 1984 until the mid-1990s, the department, along with federal agencies, undertook the cleanup of nearly 7,000 contaminated sites in Grand Junction and other parts of Mesa County; these sites—homes and properties—were contaminated during the 1950s and 1960s by radioactive mill tailings that had been used as building material and that were not considered hazardous at the time. (It is now known that the low-level radiation emitted by the mill tailings can cause cancer and genetic damage.) In the fall of 1984, Aspen was placed on the federal Environmental Protection Agency's (EPA) list of dangerous waste sites because potentially hazardous levels of cadmium, lead, and zinc were found in Aspen's streets, buildings, and water. Cadmium, lead, and zinc mill tailings had been used as filling material during the construction of the popular resort. Also in the mid-1980s, Rocky Flats, a former plutonium production site near Golden, was closed and a major cleanup was begun; by 2003 all plutonium and uranium had been removed. During 2004 and 2005 the buildings at Rocky Flats were scheduled to be demolished. Rocky Flats National Wildlife Refuge was planned for the site when the demolition was complete. (The site had been the focus of many protests during the 1970s, and has been a major newsmaker since the start of the cleanup. In 2003, the Environmental Protection Agency's database listed 202 hazardous waste sites in Colorado, 15 of which were on the National Priorities List. Some 1.5% of the state's land is covered with wetlands, a 50% decrease over the last two centuries. In 2001, Colorado received $49,955,000 in federal grants from the EPA; EPA expenditures for procurement contracts in Colorado that year amounted to $25,479,000.