An environmental impact statement is a written statement drawing conclusions on how a course of action is likely to affect the environment. In the US, the National Environmental Policy Act (NEPA) enacted in 1970 provides that the federal government and individuals or businesses must give advance notice to the public when taking any action that might have impact on the environment. The environment considered is not only the ecological, biological, and geological environment, but also the social structure of a country.
An environmental impact statement (EIS) is prepared for the government and should include the following:
1. Environmental impact that is unavoidable through the action.
2. All alternatives to the action.
3. The impact of short-term use of the environment on the long term production capacities of the environment.
4. Statements regarding the use of resources that cannot be replaced as part of the action.
5. The total effect to the environment related to the action, and other possible effects on the environment, termed secondary effects.
The environmental impact statement is then subject to review. Once reviewed, the government or private business is either given permission to proceed with an action, or to not proceed. Sometimes NEPA will approve one of the proposed alternate actions instead of the proposed action.
The environmental impact statement does not need to be prepared for all actions. Some actions are excluded from requiring an environmental impact statement. For example the Forest Service can usually take actions like controlled burning or removal of trees in small amounts without filing an environmental impact statement.
Recently, NEPA overhauled their definitions of categorical exclusions and implemented new definitions for what constitutes environmental impact. Some actions taken by a federal agency or company are now excluded. In other cases, a company or government agency need now only file an environmental assessment (EA), instead of the longer environmental impact statement form.
Environmentalists, who believed that the previous policies worked well, contested the changes. Small businesses and large corporations, conversely, supported the changes, as certain actions taken by companies can be costly when an environmental impact statement must be published. Some, however, feel that softening the rules is inappropriate when the environment is already at risk from many behaviors practiced by companies and individuals.