In a proceeding brought by the United States to restrain the construction of a dam in a stream alleged to be a "navigable river, or other navigable water of the United States," Economy Light & Power Co. v. United States2 held that "a river having actual navigable capacity in its natural state and capable of carrying commerce among the states is within the power of Congress to preserve for future transportation, even though it be not at present used for such commerce, and be incapable of such use according to present methods, either by reason of changed conditions or because of artificial obstructions." Mr. Justice Pitney declared also that "the authority of Congress to prohibit added obstructions is not taken away by the fact that it has omitted to take action in previous cases." The river in question had once been used for navigation and was a continuous stretch of water from the Chicago Divide to its mouth. Such rapids and boulders as prevented navigation at the present time did not affect navigable capacity. Therefore, the construction of a dam was enjoined.'
Thomas R. Powell,
Supreme Court's Construction of the Federal Constitution in 1920-1921,
Mich. L. Rev.
Available at: https://repository.law.umich.edu/mlr/vol20/iss2/1