In 2005, the U.S. Environmental Protection Agency (EPA) issued regulations pursuant to the Clean Air Act requiring states to submit plans to address visibility impairment due to air pollution. The regulations directed states to consider installing emissions controls at certain stationary sources according to five factors, including the cost of compliance. In Oklahoma v. U.S. Environmental Protection Agency, the U.S. Court of Appeals for the Tenth Circuit held that EPA lawfully rejected Oklahoma’s plan because the state plan failed to follow EPA-promulgated guidelines when determining the cost of compliance factor. This Comment argues that the outcome in Oklahoma was correct, however, the court did not apply the appropriate standard of review. The appropriate standard of review was to determine whether the state plan was reasonable and in compliance with the statute and EPA guidelines. EPA rightly rejected Oklahoma’s plan because the plan failed to comply with the EPA regulations on cost of compliance calculations.