Environmental Impact Statement. The U.S. National Park Service (NPS) manages the Grand Canyon National Park in Arizona under a management plan that is subject to periodic review. In 2006, after nine years of background work and the completion of a comprehensive environmental impact statement, the NPS issued a new management plan for the park.

One part of the plan allowed for the continued use of rafts on the Colorado River, which runs through the Grand Canyon.

The number of the rafts was limited, however. Several environmental groups criticized the plan because they felt that it still allowed too many rafts on the river. The groups asked a federal appellate court to overturn the plan, claiming that it violated the wilderness status of the national park. When can a federal court overturn a determination by an agency such as the NPS? Explain. [River Runners for Wilderness v. Martin, 593 F.3d 1064 (9th Cir. 2010)] (See page 869.)