Section 2. The department shall, except as otherwise provided, have charge of the lands, rights in lands, flats, shores and rights in tide waters belonging to the commonwealth, and shall, as far as practicable, ascertain the location, extent and description of such lands; investigate the title of the commonwealth thereto; ascertain what parts thereof have been granted by the commonwealth; the conditions, if any, on which such grants were made, and whether said conditions have been complied with; what portions have been encroached or trespassed on, and the rights and remedies of the commonwealth relative thereto; prevent further encroachments and trespasses; ascertain what portions of such lands may be leased, sold or improved with benefit to the commonwealth and without injury to navigation or to the rights of riparian owners; and may lease the same. It may sell and convey, or lease, any of the islands owned by the commonwealth in the great ponds. It may make contracts for the improvement, filling, sale, use or other disposition of the lands at and near South Boston known as the Commonwealth flats, may lease any portion thereof with or without improvements thereon, may regulate the taking of material from the harbor and fix the lines thereon for filling said lands. All conveyances and contracts, and all leases for more than five years, made under this section shall be subject to the approval of the governor and council.

In carrying out its duties under the provisions of this chapter, the department shall act to preserve and protect the rights in tidelands of the inhabitants of the commonwealth by ensuring that the tidelands are utilized only for water-dependent uses or otherwise serve a proper public purpose.

The department of environmental protection shall protect the interests of the commonwealth in areas described herein in issuing any license or permit authorized pursuant to this chapter. The activities of the department of environmental management pursuant to this chapter shall be subject to the licensing and permitting authority of the department of environmental protection.