# The Surface Waters (Dangerous Substances) (Classification) Regulations 1997, Paragraph 3


In relation to dichlorvos used as a treatment for sea-lice infestation, compliance with the relevant limit in column (2) of Table 4 shall be determined by reference only to samples taken as nearly as maybe after 24 hours have elapsed since it was so used.
TABLE 3
(1)
(2)
Dangerous substance
Limit (in microgrammes per litre) (annual mean)
Arsenic
25
Atrazine and Simazine
2 (for the two substances in total)
Azinphos-methyl
0.01
Dichlorvos
0.04
Endosulphan
0.003
Fenitrothion
0.01
Malathion
0.02
Trifluralin
0.1
TABLE 4
(1)
(2)
Dangerous substance
Limit (in microgrammes per litre)
Dichlorvos
0.6
Tributyltin
0.002
Triphenyltin and its derivatives
0.008

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Source: https://www.legislation.gov.uk/uksi/1997/2560/schedule/2/paragraph/3 (the official version)
Page: https://openlegislation.uk/surface-waters-dangerous-substances-classification-regulations-1997/schedule-2/paragraph-3
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.