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

Extent: N.I.
Status: prospective

Water hardness (mg/1 CaCO3)
10
50
100
500
Salmonid waters (mg/1 Zn)
0.03
0.2
0.3
0.5
Cyprinid waters (mg/1 Zn)
0.3
0.7
1.0
2.0

---
Source: https://www.legislation.gov.uk/nisr/1997/488/schedule/1/part/II (the official version)
Page: https://openlegislation.uk/surface-waters-fishlife-classification-regulations-northern-ireland-1997/schedule-1/part-II
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.