National Invasive Species Act of 1996 : hearing before the Subcommittee on Drinking Water, Fisheries, and Wildlife of the Committee on Environment and Public Works, United States Senate, One Hundred Fourth Congress, second session, on S. 1660 to Provide for Ballast Water Management to Prevent the Introduction and Spread of Nonindigenous Species into the Waters of the United States, and for Other Purposes, September 19, 1996.