7(1)Except so far as may be necessary or unavoidable in the construction of the bridge, the Secretary of State shall not, without the consent of the Port Authority (which shall not be unreasonably withheld), deposit in, or allow to fall or be washed into, the river any gravel, soil or other material.
(2)Nothing in this Act shall authorise the Secretary of State to discharge or allow to escape either directly or indirectly into the river any offensive or injurious matter in suspension.