Lakes and Watercourses

TABLE 48.
DEVIATION from reference value, watercourses, used only for watercourses that can be
assumed to contain, or have contained, fish.
Number of species 1
Class Description Recorded value/reference value
1 No or insignificant deviation ≥ 0.85
2 Slight deviation 0.70 – 0.85
3 Significant deviation 0.50 – 0.70
4 Large deviation 0.50 – 0.35
5 Very large deviation < 0.35
Weight 2 /100 m 2
Class Description 0 – 99 m ab. 100 – 299 m ab. 300 – 700 m ab. > 700 m ab.
1 No or insign. deviat. ≥ 525 ≥ 250 ≥ 105 ≥ 65
2 Slight deviation 350 – 525 175 – 250 75 – 105 45 – 65
3 Significant deviation 225 – 350 100 – 175 45 – 75 25 – 45
4 Large deviation 80 – 225 35 – 100 15 – 45 10 – 25
5 Very large deviation < 80 < 35 < 15 < 10
Number 2 /100m 2
Class Description 0 – 99 m ab. 100 – 299 m ab. 300 – 700 m ab. > 700 m ab.
1 No or insign. deviat. ≥ 1.70 ≥ 1.34 ≥ 0.98 ≥ 0.84
2 Slight deviation 1.50 – 1.70 1.05 – 1.34 0.80 – 0.98 0.60 – 0.84
3 Significant deviation 1.24 – 1.50 0.85 – 1.05 0.53 – 0.80 0.40 – 0.60
4 Large deviation 0.67 – 1.24 0.34 – 0.85 0.30 – 0.53 0.30 – 0.40
5 Very large deviation < 0.67 < 0.34 < 0.30 < 0.30
Proportion of salmonids (flow = < 0.2 m/s – Calm)
Class Description 0 – 99 m ab. 100 – 299 m ab. 300 – 700 m ab. > 700 m ab.
1 No or insign. deviat. ≥ 0.77 ≥ 0.31 ≥ 0.86 ≥ 0.95
2 Slight deviation 0.53 – 0.77 0.15 – 0.31 0.54 – 0.86 0.80 – 0.95
3 Significant deviation 0.23 – 0.53 0.10 – 0.15 0.16 – 0.54 0.61 – 0.80
4 Large deviation 0.05 – 0.23 0.05 – 0.10 0.05 – 0.16 0.40 – 0.61
5 Very large deviation < 0.05 < 0.05 < 0.05 < 0.40
Contd. ➤
78