(1)The Development Corporation shall operate the barrage in accordance with any reasonable direction given by the National Rivers Authority in order—
(a)to protect the quality of water in the inland bay by ensuring that it meets or continues to meet the relevant standard,
(b)to prevent or alleviate flooding, or
(c)to protect fish in the inland bay, allow the passage of migratory fish to or from the inland bay or enable trials to be carried out in the inland bay in connection with fishery management.
(2)For the purposes of this section the quality of water meets the relevant standard—
(a)if it meets such standard, whether fixed by reference to dissolved oxygen content or any other determinant of water quality, as may reasonably be specified by the National Rivers Authority as the standard to be achieved in order to comply with the current water quality objectives for the water, or
(b)where no standard is specified under paragraph (a) above, if it contains not less than five milligrams dissolved oxygen per litre at all times.
(3)For the purposes of subsection (2)(a) above the water quality objectives for any water are—
(a)if water quality objectives have been established for the water under section 83 of the [1991 c. 57.] Water Resources Act 1991, those objectives, and
(b)if they have not, such reasonable objectives as may be set by the National Rivers Authority for the water having regard to—
(i)the recreational or other purposes for which use of the water is permitted, or proposed to be permitted, by the Development Corporation, and
(ii)the needs of the fish in the water and of migratory fish passing to or from it.
(4)Subject to subsection (5) below, notice of a direction under subsection (1) above—
(a)shall be given in writing by a duly authorised officer of the National Rivers Authority, and
(b)shall be given as long as possible, but in any case not less than twenty-four hours, before the direction is to be complied with.
(5)In case of emergency notice of such a direction—
(a)may be given orally to be complied with as soon as it is practicable to do so, but
(b)shall be confirmed as soon as may be by notice given as required by subsection (4)(a) above.
(6)Where there arises any dispute as to the reasonableness of—
(a)any direction given under subsection (1) above, or
(b)any standard specified under subsection (2)(a) above or objectives set under subsection (3)(b) above,
the matter shall be referred to the Secretary of State for determination by him.