29.—(1) The appropriate authority may, by regulations, make provision—
(a)about the procedure for establishing threshold values, under retained EU law which implemented the Groundwater Directive, for pollutants and indicators of pollutants which indicate that a body of groundwater is at risk of failing to achieve good groundwater chemical status;
(b)specifying the information relating to threshold values which is to be included in river basin management plans, which may include—
(i)information about bodies of groundwater or groups of such bodies characterised as being at risk;
(ii)the threshold values that have been set and the area to which they apply;
(iii)the methodology for determining background levels;
(iv)information about the groundwater chemical status assessment.
(2) The provision which may be made under paragraph (1) includes—
(a)requiring a reference to Part A or Part C of Annex 2 to the Groundwater Directive (or a reference which encompasses that provision) to be read as a reference to that provision with modifications;
(b)amending provision corresponding to provision made by Part A or Part C of Annex 2 to the Groundwater Directive.
(3) Regulations under paragraph (1) may amend the WEWS Act or subordinate legislation.
(4) The appropriate authority may only exercise the power in paragraph (1) to the extent that the authority considers it is appropriate to do so as a result of scientific and technical progress.
(5) In this regulation, “background levels” means the concentration of a substance or the value of an indicator in a body of groundwater corresponding to no, or only very minor, anthropogenic alterations to undisturbed conditions.