Beginning in the late 1960s, the US Congress passed an unprecedented suite of laws to protect the environment. The laws described here particularly influence the management of our national parks.
The Wilderness Act of 1964 particularly influences the management of national parks.
The National Environmental Policy Act (NEPA), passed in 1970, establishes a national policy “to promote efforts which will prevent or eliminate damage to the environment … stimulate the health and welfare of man … and enrich the understanding of ecological systems …” It requires detailed analysis of environmental impacts of any major federal action that significantly affects the quality of the environment. Environmental assessments (EAs) and environmental impact statements (EISs) are written to detail these analyses and to provide forums for public involvement in management decisions.
The Clean Air Act (1970) mandates protection of air quality in all units of the National Park System; Yellowstone is classified as Class 1, the highest level of clean air protection.
The Clean Water Act (1972) is enacted to “restore and maintain the chemical, physical, and biological integrity of the Nation’s waters” by prohibiting the discharge of pollutants.
The Endangered Species Act (1973) requires federal agencies to protect species that are (or are likely to become) at risk of extinction throughout all or a significant part of their range. It prohibits any action that would jeopardize their continued existence or result in the destruction or modification of their habitat.