Sampling Ballast Water in Baltimore Harbor, by Reid, Don, 1994, Smithsonian Archives - History Div, Linda McCann (left) of the Smithsonian Environmental Research Center (SERC), and David Smith and Marjorie Wonham of Williams College in Massachusetts sample ballast water in Baltimore Harbor. Foreign and domestic cargo ships jettison millions of gallons of ballast water into North American ports and waterways. Drawn aboard in foreign countries to stabilize large ships during ocean crossings, this water can contain hundreds of species of marine or freshwater organisms. Biologists call the discharge of these organisms "ecological roulette" on a global scale, and the result may cause irreversible changes in marine estuaries and freshwater ecosystems. This discharge of ballast water from foreign ports makes the Chesapeake Bay a hotspot for the release of alien species and their potential invasion..