# The Surface Waters (Fishlife) (Classification) Regulations (Northern Ireland) 1997, Part I: Guideline values in relation to the quality of salmonid and cyprinid waters

Extent: N.I.
Status: prospective

No in Annex 1 to 78/659/EEC
Parameter
Salmonid waters (guideline values and comments)
Cyprinid waters (guideline values and comments)
Methods of analysis or inspection
Minimum sampling and measuring frequency
Observations
2.
Dissolved oxygen (mg/1O2)
50%≥9
100%≥7
50%≥8
100%≥5
Winkler’s method or specific electrodes (electro- chemical method)
Monthly, minimum sample represent- ative of low oxygen conditions on the day of sampling. However, where major daily variations are suspected, a minimum of 2 samples in 1 day shall be taken
4.
Suspended solids (mg/1)
≤25(O)
Filtration through a 0.45μm filtering membrane, or centrifugation (5 minutes minimum, average acceleration of 2,800 to 3,200g) drying at 105°C and weighing
The values shown are average concentrations and do not apply to suspended solids with harmful chemical properties Floods are liable to cause particularly high concentrations
5.
BOD5 (mg/1O2)
≤3
≤6
Determination of O2 by the Winkler method before and after 5 days incubation in complete darkness at 20°C ±1°C (nitrification should not be inhibited)
7.
Nitrites (mg/1 NO2)
≤0.01
≤0.03
Molecular absorption spectro- photometry
10.
Non-ionized ammonia (mg/1 NH3)
≤0.005
≤0.005
Molecular absorption spectro- photometry using indophenol blue or Nessler’s method associated with pH and temperature determ-ination
Monthly
Values for non-ionized ammonia may be exceed in the form of minor peaks in the daytime.
11.
Total ammonium (mg/1 NH4)
In order to diminish the risk of toxicity due to non-ionised ammonia, of oxygen consumption due to nitrification and of eutrophication, the concentrations of total ammonium should not exceed 0.04 mg/1 for salmonid waters and 0.2 mg/1 for cyprinid waters
14.
Dissolved copper (mg/1 Cu)
≤0.04
≤0.04
Atomic absorption spectrometry
The values correspond to a water hardness of 100 mg/1 CaCO3 For hardness levels between 10 and 300 mg/1 corresponding limit values can be found in Part II of this Schedule

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