# The Surface Waters (Fishlife) (Classification) Regulations (Northern Ireland) 1997, Part II: Copper concentrations (mg/1 Cu) for different water hardness values between 10 and 500 mg/l CaCO3

Extent: N.I.
Status: prospective

Water hardness (mg/1 CaCO3)
(1)The presence of fish in waters containing higher concentrations of copper may indicate a predominance of dissolved organo-cupric complexes.
10
50
100
500
mg/1 Cu
0.005
0.02
0.04
0.112

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Source: https://www.legislation.gov.uk/nisr/1997/488/schedule/2/part/II (the official version)
Page: https://openlegislation.uk/surface-waters-fishlife-classification-regulations-northern-ireland-1997/schedule-2/part-II
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.