# The Surface Waters (Shellfish) (Classification) Regulations (Northern Ireland) 1997, Schedule 2: Guideline values in relation to the quality of shellfish waters

Extent: N.I.
Status: prospective

No in Annex 1 to 79/923/EEC
Parameter
Units
Guideline values and comments
Reference methods of analysis
Minimum sampling and measuring frequency
2.
Temperature
°C
A discharge affecting shellfish waters must not cause the temperature of the water to exceed by more than 2°C the temperature of waters not so affected
— Thermometry Measured in situ at the time of sampling
Quarterly
5.
Salinity
‰
12 to 38‰
Conductivity
Monthly
6.
Dissolved oxygen
saturation %
≥80%
Winkler’s method
Electrochemical method
Monthly, with a minimum of 1 sample representative 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
8.
Organohalo- genated substances
The concentration of each substance in shellfish flesh must be so limited that in contributes, in accordance with Article 1 of Directive 79/923/EEC, to the high quality of shellfish products
Gas chromatography after extraction with suitable solvents and purification
Half-yearly
9.
Metals
Silver Ag
Arsenic As
Cadmium Cd
Chromium Cr
Copper Cu
Mercury Hg
Nickel Ni
Lead Pb
Zinc Zn
mg/1
The concentration of each substance in shellfish flesh must be so limited that it contributes in accordance with Article 1 of Directive 79/923/EEC, to the high quality of shellfish products
Spectrometry of atomic absorption preceded, where appropriate, by concentration and/or extraction
Half-yearly
10.
Faecal coliforms
≤300 in the shellfish flesh and intervalvular liquid
Method of dilution with fermentation in liquid substrates in at least 3 tubes in 3 dilutions.
Subculturing of the positive tubes on a confirmation medium. Count according to MPN (most probable number).
Incubation temperature 44° ± 0.5°C
Quarterly

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Source: https://www.legislation.gov.uk/nisr/1997/489/schedule/2 (the official version)
Page: https://openlegislation.uk/surface-waters-shellfish-classification-regulations-northern-ireland-1997/schedule-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.