Thomas, J., concurring
channels of interstate commerce over which Congress traditionally exercised authority.
3
This understanding of the term “navigable waters”—i.e., as shorthand for waters subject to Congress’ authority under the Daniel Ball test—persisted up to the enactment of the CWA. See, e.g., Stoeco Homes, Inc., 498 F. 2d, at 608–609; United States v. Joseph G. Moretti, Inc., 478 F. 2d 418, 428–429 (CA5 1973); see also D. Guinn, An Analysis of Navigable Waters of the United States, 18 Baylor L. Rev. 559, 579 (1966) (“[T]he test of The Daniel Ball and Appalachian Power Co. are religiously cited as being the basis for the holding on the issue of navigability”). As a court observed near the time of the CWA’s enactment, “[a]lthough the definition of ‘navigability’ laid down in The Daniel Ball has subsequently been modified and clarified, its definition of ‘navigable water of the United States,’ insofar as it requires a navigable interstate linkage by water, appears to remain unchanged.” Hardy Salt Co. v. Southern Pacific Transp. Co., 501 F. 2d 1156, 1167 (CA10 1974) (citations omitted). This Court’s cases, too, continued to apply traditional navigability concepts in cases under the River and Harbor Acts right up to the CWA’s enactment. See United States v. Standard Oil Co., 384 U. S. 224, 226 (1966) (holding that spilling oil in a navigable water was prohibited by the Refuse Act (§13 of the 1899 Act) because “its presence in our rivers and harbors is both a menace to navigation and a pollutant”); United States v. Republic Steel Corp., 362 U. S. 482, 487–491 (1960) (“diminution of the navigable capacity of a waterway” required for violation of the Refuse Act). Thus, on the eve of the CWA’s enactment, the term “navigable waters” meant those waters that are, were, or could be used as highways of interstate or foreign commerce.
