Section 34. The department of environmental protection may, after hearing the parties interested, prescribe lines in any harbor of the commonwealth and make report thereof to the general court, not later than the next session, for its action, thereon. If such lines are established by the general court as the harbor lines of said harbor, no wharf, pier or other structure shall thereafter be extended into said harbor beyond such lines, except as provided by section fourteen. Notice of the hearing shall be published three weeks successively in a newspaper published in Boston and in one or more published in the county or counties where such harbor lies, the first publication to be at least thirty days before the hearing.