Why are environmental impact assessments required before some major projects?

Environmental impact assessments are required for major projects to ensure that the potential environmental consequences of a proposed action are thoroughly analyzed before a decision is made. These mandates serve several critical functions:12

• Informed Decision-Making: They increase the quantity and quality of publicly available information regarding environmental impacts, which improves the decision-making process for government officials.1
• Alternative Consideration: They require agencies to evaluate a range of alternatives, including a "no-action alternative," ensuring that less harmful options are considered before proceeding.12
• Public Participation: They provide opportunities for the public and interested organizations to review and comment on proposed projects, fostering greater transparency and involvement in environmental policy.12
• Comprehensive Analysis: Assessments describe and evaluate direct and indirect effects on humans, soil, water, air, climate, and landscape.1

While these assessments do not inherently prohibit actions that may harm the environment, they serve as a vital mechanism to ensure that environmental consequences are explicitly considered as a factor in the planning and execution of significant projects.2