11.—(1) At the end of every bathing season, for every bathing water, the Department shall—
(a)prepare a set of bathing water quality data for that season; and
(b)carry out a bathing water quality assessment using the set of bathing water quality data compiled in relation to that season and the relevant assessment period.
(2) In this regulation, the “relevant assessment period” is—
(a)the immediately preceding three bathing seasons;
(b)the immediately preceding two bathing seasons, where the Department so decides in accordance with paragraph (3); or
(c)the number of immediately preceding bathing seasons, being less than three, that the Department so decides in accordance with paragraph (4).
(3) The Department may make a decision under paragraph (2)(b) where—
(a)it is at least five years since the last change in the relevant assessment period; and
(b)the set of bathing water quality data is based on at least 16 samples.
(4) The Department may make a decision under paragraph 2(c) where—
(a)it considers that any factors identified in the bathing water profile as likely to affect the classification of the bathing water under regulation 12 have changed, and the set of bathing water quality data used is based only on samples taken since those factors have changed; and
(b)the set of bathing water quality data is based on at least 16 samples.
(5) The Department may—
(a)subdivide existing bathing waters in the light of the bathing water quality assessments carried out under this regulation; or
(b)group together existing bathing waters in light of those assessments where those bathing waters—
(i)are contiguous;
(ii)have received similar assessments for the preceding four years; and
(iii)have bathing water profiles which identify common pollution risk factors or the absence thereof.