Final answer:
An Environmental Impact Statement is required under NEPA when a federal project, like pipeline construction, could significantly affect the environment. It discusses potential impacts, unavoidable adverse effects, alternatives, and resource commitments.
Step-by-step explanation:
An Environmental Impact Statement (EIS) must be prepared when a federal action is anticipated to significantly affect the quality of the human environment. The National Environmental Policy Act (NEPA) mandates this requirement. The purpose of an EIS is to ensure that environmental factors are weighed equally when considering proposed projects and that the public is informed about potential environmental impacts.
The EIS must discuss several critical aspects, including the positive and negative environmental impacts of the proposal, any adverse effects that cannot be avoided, alternatives to the proposed action, the relationship between local short-term uses of the environment and the maintenance of long-term productivity, and any irreversible commitments of resources involved.
An example of when an EIS might be necessary is in the case of pipeline construction. For instance, an impact statement might consider alternative routes that avoid environmentally sensitive areas or analyze if construction would harm vital resources, such as an aquifer system. As part of the EIS, environmental impact assessments help determine the extent of the effects of the project on the environment and are crucial in the decision-making process.