Environmental Impact Review (NEPA)

Environmental impact review is the process the federal government follows before it builds, funds, or approves major projects—highways, pipelines, power plants, mines, and more. The core law behind it is the National Environmental Policy Act, which requires agencies to study how a proposed project might affect the land, air, water, and communities around it before construction begins. That requirement gives ordinary residents a formal way to learn about, comment on, and sometimes challenge federal decisions that touch their own backyards.

How the review works. Agencies must weigh a project’s likely environmental effects, consider alternatives, and explain their reasoning in a public document. The depth of that review depends on how significant the effects are expected to be, and the process built for it shapes projects long before any shovel hits the ground, as explained in How NEPA Environmental Reviews Shape Federal Projects in Your Community.

Where it applies. Environmental review touches an enormous range of federal activity, from decisions about offshore energy leasing to permits for new infrastructure tied to emerging industries like large-scale computing. The rules that govern offshore drilling rights show how multiple agencies and legal processes intersect on a single kind of project, detailed in How Offshore Oil Drilling Rights Are Decided in the United States. Newer, fast-growing sectors face the same scrutiny, as seen in The Environmental Reviews Required Before Building a Massive Data Center.

Why it matters. Supporters see environmental review as a safeguard against unchecked development; critics argue it can slow projects that communities and the economy need. Both views turn on the same question: how much study is enough before the government commits public land, money, or approval to a project that will outlast the debate over it.