Plenty, especially if the word is "navigable," and it is used in legislation to state what waters the EPA can regulate.
A narrow definition of navigable by the Supreme Court (in two cases: Solid Waste Agency of Northern Cook County v. United States Army Corps of Engineers in 2001 and Rapanos v. United States in 2006) has, according to the New York Times, led to increased levels of water pollution in the country. The majority stuck to what it considered to be the plain meaning of the text, despite arguments by others that that negated the intent of the act itself.
Congress is currently determining whether to revise the Clean Water Act to restore the intended broad intent of the law.
