Pollution of navigable waters resulting from operation of watercraft, currently not considered serious in comparison with other known pollutants, is expected to become more serious with the steady increase in recreational watercraft. Main causes of pollution are discharge of sewage, dunnage, and other wastes; occasional spills of oil, chemicals, grains, etc., resulting from accidents; and related activities such as servicing and cleaning equipment. Main problem areas are docks and marinas where boats are serviced and large numbers of watercraft congregate. Pollution problems can be improved by requiring installation of sewage treatment devices on all boats having toilet facilities and installation of onshore facilities for handling waste stored on watercraft.