# The Surface Waters (Fishlife) (Classification) Regulations (Northern Ireland) 1997, Part I: Criteria for classification of water as salmonid and cyprinid waters

Extent: N.I.
Status: prospective

No in Annex 1 to 78/659/EEC
Parameter
Requirements to be satisfied for salmonid waters
Requirements to be satisfied for cyprinid waters
Methods of analysis or inspection
Minimum sampling and measuring frequency
Observations
1.
Temperature (°C)
1 Temperature measured downstream of a point of thermal discharge (at the edge of the mixing zone) must not exceed the unaffected temperature by more than 1.5°C for salmonid waters and 3°C for cyprinid waters.Derogations limited in geographical scope may be decided by the Department in particular conditions if it can prove that there are no harmful consequences for the balanced development of the fish population.
2 Thermal discharges must not cause the temperature downstream of the point of thermal discharge (at the edge of the mixing zone) to exceed—
(a) 10°C(O) during the breeding season in the case of waters which contain species which need cold water for reproduction;
(b) at other times or in the case of waters which do not contain such species, 21.5°C(O) for salmonid waters and 28°C(O) for cyprinid waters.
Temperature limits may, however, be exceeded for 2% of the time.
Thermometry
Weekly, both upstream and downstream of the point of thermal discharge.
Over-sudden variations of temperature shall be avoided.
2.
Dissolved oxygen (mg/1O2)
50%≥9
When the oxygen con- centration falls below 6 mg/1, the Department shall comply with regulation 7(6). The Department must prove that this situation will have no harmful con- sequences for the balanced development of the fish population
50%≥7
When the oxygen con- centration falls below 4 mg/1, the Department shall comply with regulation 7(6). The Department must prove that this situation will have no harmful con- sequences for the balanced development of the fish population
Winkler’s method or specific electrodes (electro- chemical method)
Monthly, minimum 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
3.
pH
6 to 9(O)
Artificial pH variations with respect to the unaffected values shall not exceed ±0.5 of a pH unit within the limits falling between 6.0 and 9.0 provided that these variations do not increase the harmfulness of other substances present in the water.
Electrometry calibration by means of 2 solutions with known pH values, preferably on either side of, and close to, the pH being measured
Monthly
8.
Phenolic compounds (mg/1 C6H5OH)
Phenolic compounds must not be present in such concentrations that they adversely affect fish flavour.
By taste
An examination by taste shall be made only where the presence of phenolic com- pounds is presumed
9.
Petroleum hydro- carbons
Petroleum products must not be present in water in such quantities that they—
(a) form a visible film on the surface of the water or form coatings on the beds of watercourses and lakes,
(b) impart a detectable ‘hydrocarbon' taste to fish,
(c) produce harmful effects in fish.
Visual By taste
Monthly
A visual examination shall be made regularly once a month, with an examination by taste only where the presence of hydrocarbons is presumed
10.
Non-ionized ammonia (mg/1 NH3)
≤0.025
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 exceeded in the form of minor peaks in the day- time.
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 1mg/1 In particular geographical or climatic conditions and particularly in cases of low water temperature and of reduced nitrification or where the Department can show that there are no harmful consequences for the balanced development of fish population, the Department may fix a value higher than 1mg/1.
12.
Total residual chlorine (mg/1 HOC1)
≤0.005
≤.005
DPD- method diethyl-p- phenylen- ediamene)
Monthly
The values correspond to pH = 6 Higher concentrations of total chlorine can be accepted if the pH is higher
13.
Total zinc (mg/1 Zn)
≤0.3
≤1.0
Atomic absorption spectro- metry
Monthly
The values correspond to a water hardness of 100 mg/1 CaCO3 For hardness levels between 10 and 500 mg/1 corres- ponding limit values can be found in Part II

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