This bill amends the National Environmental Policy Act of 1969 (NEPA) to streamline the environmental review process for federal agencies. Its primary purpose is to allow agencies to leverage existing environmental documentation, such as environmental assessments and environmental impact statements, for new major federal actions. Specifically, a lead agency may satisfy NEPA requirements by relying on a previously completed environmental assessment or impact statement if the new major federal action is substantially the same as the prior action or an analyzed alternative, and its effects are also substantially the same. If the new action is not substantially the same, the lead agency is authorized to modify any such previously completed document as necessary to meet NEPA requirements, making the modified document publicly available.