(1)A person shall not be guilty of an offence under section 85 above in respect of the entry of any matter into any waters or any discharge if—
(a)the entry is caused or permitted, or the discharge is made, in an emergency in order to avoid danger to life or health;
(b)that person takes all such steps as are reasonably practicable in the circumstances for minimising the extent of the entry or discharge and of its polluting effects; and
(c)particulars of the entry or discharge are furnished to the Authority as soon as reasonably practicable after the entry occurs.
(2)A person shall not be guilty of an offence under section 85 above by reason of his causing or permitting any discharge of trade or sewage effluent from a vessel.
(3)A person shall not be guilty of an offence under section 85 above by reason only of his permitting water from an abandoned mine to enter controlled waters.
(4)A person shall not, otherwise than in respect of the entry of any poisonous, noxious or polluting matter into any controlled waters, be guilty of an offence under section 85 above by reason of his depositing the solid refuse of a mine or quarry on any land so that it falls or is carried into inland freshwaters if—
(a)he deposits the refuse on the land with the consent of the Authority;
(b)no other site for the deposit is reasonably practicable; and
(c)he takes all reasonably practicable steps to prevent the refuse from entering those inland freshwaters.
(5)A highway authority or other person entitled to keep open a drain by virtue of section 100 of the [1980 c. 66.] Highways Act 1980 shall not be guilty of an offence under section 85 above by reason of his causing or permitting any discharge to be made from a drain kept open by virtue of that section unless the discharge is made in contravention of a prohibition imposed under section 86 above.
(6)In this section “mine” and “quarry” have the same meanings as in the [1954 c. 70.] Mines and Quarries Act 1954.