Section 20. Whoever is authorized by the general court to build over tide waters a bridge, wharf, pier or dam, to fill flats or drive piles below high water mark, or to build any structures in the Connecticut river, or in the non-tidal part of the Merrimack river, or to build or extend any structure or to do any other work mentioned in the preceding section in, over or upon the waters of any great pond, shall not commence such work until he has given written notice thereof to the department and submitted plans of any proposed structure, the flats to be filled, and the manner in which the work is to be performed, and the same has been approved in writing by the department, which may alter such plans and prescribe any direction, limits and manner of doing the work consistent with the legislative grant. Such works shall be supervised by the department.