Section 70. No person shall deface or injure any part of the Charles river dam, or any wharf, wall or other structure or any mechanism connected therewith, or unnecessarily open any drawbridge connected therewith or obstruct the passage thereof; nor shall any person, without the consent of the person in charge of the drawbridge, make fast to the dam, bridge, draw, guard, pier or any appurtenance thereof any vessel, scow, raft or float, or remain inside of the draw gates or on any pier, wharf, fender or appurtenance of the draw while the gates are closed; nor shall any person having charge of a vessel passing through the draw of such bridge refuse or neglect to comply with the directions of the person in charge relating to such passing. Whoever violates any provision of this section shall be punished by a fine of not more than twenty dollars.