Section 12 Dams and reservoirsI1

the construction of a dam or reservoir in Wales if the volume of water to be held back by the dam or stored in the reservoir is expected to exceed 10 million cubic metres;

the alteration of a dam or reservoir in Wales if the additional volume of water to be held back by the dam or stored in the reservoir as a result of the alteration is expected to exceed 10 million cubic metres.