“ When the United States appropriates the flow either of a navigable or a nonnavigable stream pursuant to its superior power under the Commerce Clause, it is exercising established prerogatives and is beholden to no one. Plainly under our decisions it could license another to build the project and operate it. If respondent sued for damages for failure of the Federal Government to grant it a license to build the Ft. Gibson project, it could not claim that something of right had been withheld from it. So it is when the United States exercises its prerogative by building the project itself. ”

“ The Court of Claims erred in failing to distinguish between an appropriation of property and the frustration of an enterprise by reason of the exercise of a superior governmental power. Here respondent has done no more than prove that a prospective business opportunity was lost. More than that is necessary as Omnia Commercial Co. v. United States, 261 U.S. 502, 43 S.Ct. 437, 67 L.Ed. 773, holds. In that case the claimant stood to make large profits from a contract it had with a steel company. But the United States, pursuant to the War Power, requisitioned the company's entire steel production. ”

“ Suit was brought in the Court of Claims for just compensation. The Court, after pointing out that many laws and rulings of Government reduce the value of property held by individuals, noted that there the Government did not appropriate what the claimant owned but only ended his opportunity to exploit a contract. ”