Section 137. Whoever, by erecting or maintaining a dam, either within or without the commonwealth, knowingly causes the water of a river or stream so to be raised as to flow upon or injure a mill lawfully existing in the commonwealth and belonging to a citizen thereof, without right as against the owner of such mill, shall be punished by a fine of not more than one thousand dollars or by imprisonment for not more than six months; but this section shall not apply to cases in which the courts of the commonwealth have jurisdiction to abate a dam so raised or maintained.