(1)Each instrument signifying the consent of a water authority in pursuance of section 34 of this Act shall specify a period during which no notice in pursuance of subsection (1) of the preceding section is to be served in respect of the consent without the written agreement of a person making a discharge in pursuance of the consent; and the said period shall be a reasonable period of not less than two years beginning with the day on which the consent takes effect.
(2)Each notice served by a water authority in pursuance of subsection (1) of the preceding section (except a notice which only revokes a consent or conditions) shall specify a period during which a subsequent notice in pursuance of that subsection which alters the effect of the first-mentioned notice is not to be served without the written agreement of a person making a discharge in pursuance of the consent to which the first-mentioned notice relates; and the said period shall be a reasonable period of not less than two years beginning with the day on which the first-mentioned notice is served.
(3)Nothing in the preceding provisions of this section shall prohibit a notice in pursuance of subsection (1) of the preceding section from being served by a water authority, without such written agreement as is mentioned in those provisions and during the period specified in any relevant instrument or notice by virtue of those provisions, if the authority (or, in the case of a notice served by virtue of subsection (2) of that section, the Secretary of State) considers—
(a)that it is necessary to serve the notice in order to provide proper protection for persons likely to be affected by discharges which could lawfully be made apart from the notice; or
(b)in the case of a notice relating to a consent given by an instrument served in pursuance of subsection (3) of section 34 of this Act, that it is appropriate to serve the notice in consequence of representations received in pursuance of section 36(1) of this Act with respect to the instrument.
(4)Where a notice is served by an authority by virtue of the preceding subsection, the authority shall be liable to pay compensation to the recipient of the notice unless it is served in pursuance of the said subsection (1) and not by virtue of the said subsection (2) and either—
(a)it states that in the opinion of the authority the notice is required—
(i)in consequence of a change of circumstances (which may include a change in the information available as to the discharges to which the notice relates or as to the interaction of those discharges with other discharges or matter) which has occurred since the day mentioned in subsection (1) or, as the case may be, subsection (2) of this section and could not reasonably have been foreseen on that day, and
(ii)otherwise than in consequence of consents given in pursuance of the said section 34 after that day, and states the reasons for the opinion; or
(b)the relevant consent was given by an instrument served in pursuance of subsection (3) of the said section 34 and the notice is served during the period of three months beginning with the date on which notice of the instrument was published in the London Gazette in pursuance of section 36(1) of this Act.
(5)Provision may be made by regulations as to the manner of determining the amount of any compensation payable in pursuance of this section including the factors to be taken into account in determining that amount.