Ninth Circuit holds in San Francisco Baykeeper v. Cargill Salt Division (Nos. 04-17554, 05-15-51, Mar. 8, 2007):
We conclude that the district court improperly expanded the regulatory definition of "waters of the United States" when it held that bodies of water that are adjacent to navigable waters are subject to the CWA [federal Clean Water Act] by reason of that adjacency. Our conclusion is based on the CWA, the regulations promulagated by the agencies responsible for administering it, and the decisions of the Supreme Court addressing the reach of the Act and its regulations.
More on the CWA here.