When any such corporation shall have purchased any canal or other improvements, lands, or other property of any such other corporation under the provisions of section 24 of this act, the rate of tolls shall not thereafter be increased, but the corporation purchasing shall be entitled to collect the tolls established and existing at the time of such purchase, and no other additional charges shall be imposed. And when any corporation formed under the provisions of this act shall have made improvements on or at the mouth of any navigable stream, said corporation is hereby required to furnish reasonable facilities in said harbor, in, at, or near the mouth of said stream for the making up of rafts at such place and in such manner that it will be practicable to float such rafts to the lake. They shall also be required to furnish reasonable facilities for operating, tying up, or anchoring, as the case may be, such rafts, or any tugs or boats necessary to be used in making up or removing such rafts: Provided, That nothing in this act shall be construed as conferring upon the log interest any paramount rights, nor as authorizing any unnecessary interference with the rights of the public in any navigable waters, nor any unnecessary interference with the rights or privilege of the owners of the adjacent banks or shore, except as hereinbefore provided.