Mass. Gen. Laws ch. 21, § 65
(a) As used in this section and section 66, the following words shall, unless the context clearly require otherwise, have the following meanings:—
''High hazard dam'', a dam located where structural failure will likely cause loss of life and serious damage to homes, industrial or commercial facilities, essential public utilities, main highways or railroads.
''Low hazard dam'', a dam located where structural failure may cause minimal property damage and loss of life is not expected.
''Significant hazard dam'', a dam located where structural failure may cause loss of life and damage to homes, industrial and commercial facilities, secondary highways or railroads or interruption of use of service of relatively important facilities.