(1)Where by reason of an exceptional shortage of rain or of any unforeseen event having a substantial effect on the availability of water it appears to a river purification authority that it is necessary to do so, they may limit or suspend the operation of any licence under this Part of this Act relating to affected waters.
(2)A limitation or suspension imposed under subsection (1) above shall apply equitably to all licences relating to the affected waters and it shall have effect until the river purification authority decide that it is no longer necessary.
(3)Where by reason of an abundance of water it appears to a river purification authority that restrictions on the abstraction of water in a control area may be temporarily relaxed or lifted, the authority may so declare and shall relax the operation of licences under this Part relating to the affected waters to the extent authorised by the declaration (which shall apply equitably to all such licences).
(4)A relaxation or lifting of restrictions on the abstraction of water, whether under licence or not, shall have effect until the river purification authority declare that these restrictions are again to apply.
(5)A river purification authority shall communicate any decision taken by them under this section to the holder of any licence affected by such decision.