Section 50B. As used in sections 50C to 50E, inclusive, the following words shall, unless the context clearly requires otherwise, have the following meaning:—

''Area of special interest'' any water of the commonwealth that is found by the secretary of environmental affairs to contain 1 or more immobile obstacles to navigation, abut or include areas of critical environmental concern, are designated as an estuary of national significance, abut or include habitat for endangered species, abut or include public recreation areas, support shell fishing, fin fishing or tourist industries or abut or include sensitive public safety areas. Such waters shall include, but not be limited to, Buzzards bay, Vineyard sound and Mount Hope bay.

''Department'', the department of environmental protection.

''Discharge'', any spilling, leaking, pumping, pouring, emitting, emptying, discharging, injecting, escaping, leaching, releasing, dumping or disposing into the environment.

''Hazardous material'', material including, but not limited to, material, in whatever form, which, because of its quantity, concentration, chemical, corrosive, flammable, reactive, toxic, infectious or radioactive characteristics, either separately or in combination with any other substance, constitutes a present or potential threat to human health, safety or welfare or to the environment. The term shall also include all those substances which are included under 42 USC Sec. 9601(14), but shall not be limited to those substances.

''Hazardous waste'', a waste, or combination of wastes, which because of its quantity, concentration or physical, chemical or infectious characteristics may cause, or significantly contribute to an increase in mortality or an increase in serious irreversible, or incapacitating reversible illness or pose a substantial present or potential hazard to human health, safety or welfare or to the environment.

''Oil'', insoluble or partially soluble oil of any kind or origin or in any form including, but not limited to, crude or fuel oil, lube oil or sludge, asphalt and soluble or partially soluble derivatives of mineral, animal or vegetable oil.

''Vessel'', every description of watercraft or other artificial contrivance used, or capable of being used, as a means of transportation on water.