5. For the priority substances numbered 2, 5, 15, 20, 22, 23 and 28 in Table 47 of Part 2 of Schedule 1, with the aim of achieving good surface water chemical status in relation to those substances by 22 December 2021 by means of the programme of measures included in the river basin management plans (or an update of them), the environmental quality standards that apply are those applicable on the dates set out in column 4 of that Table. For all other priority substances numbered 1-33, the environmental quality standard set out in Table 47 of Part 2 of Schedule 1 applies from the date these Regulations come into force.