Water Quality
Water
Quality Criteria for Nitrogen (Nitrate, Nitrite, and Ammonia)
Overview
Report
Prepared
pursuant to Section 2(e) of the
Environment Management Act, 1981
R.
N. Nordin Ph.D.
L. W. Pommen M.Sc. P.Eng.
Resource Quality Section
Water Management Branch
Ministry of Environment and Parks (now called
Ministry of Water, Land and Air Protection)
Original
signed by Ben Marr
Deputy Minister
November 12, 1986
Updated:
August 7, 2001
Table
of Contents
Tables
Preface
Recommended
Guidelines
Application
of the Guidelines
NOTE:
The marine ammonia criteria found in this document have been
replaced by newer values found in the document Ambient
Water Quality Guidelines for Ammonia to Protect Marine Aquatic
Life.
Tables
Table
1. Summary of Water Quality Criteria for Nitrogen
Water
Use
|
Nitrate
mg/L as Nitrogen
|
Nitrite
mg/L as Nitrogen
|
Ammonia
(total)
mg/L as Nitrogen
|
Drinking
Water
|
10
mg/L (maximum)
|
1
mg/L (maximum)
|
None proposed
|
Fresh
Water Aquatic Life - maximum
|
200
mg/L (maximum)
|
0.06
mg/L (maximum)
|
|
Fresh
Water Aquatic Life - average
|
less
than or equal to 40 mg/L (average)
|
0.02
mg/L (average) when the chloride is less than or equal
to 2 mg/L - also see
Table 2
|
|
Marine
Aquatic Life - maximum
|
None
proposed
|
None
proposed
|
2.5 mg/L (maximum)
|
Marine
Aquatic Life - average
|
None
proposed
|
None
proposed
|
less than or
equal to 1.0 mg/L (average)
|
Livestock
Watering
|
100
mg/L (maximum)
|
10
mg/L (maximum)
|
None proposed
|
Wildlife
|
100
mg/L (maximum)
|
10
mg/L (maximum)
|
None proposed
|
Recreation
and Aesthetics
|
10
mg/L (maximum)
|
1
mg/L (maximum)
|
None proposed
|
1.
The average value is calculated from at least 5 weekly
samples taken in a period of 30 days.
2.
Where nitrate and nitrite are present, the total
nitrate-nitrite nitrogen should not exceed these
values.
|
Return
to the Table of Contents
Table
2. Criteria for Nitrite for Protection of Freshwater Aquatic
Life
Chloride
in mg/L
|
Nitrite
(maximum) mg/L as Nitrogen
|
Nitrite
(average)
mg/L as Nitrogen
|
less
than 2 mg/L
|
0.06
mg/L
|
0.02
mg/L
|
2
to 4 mg/L
|
0.12
mg/L
|
0.04
mg/L
|
4
to 6 mg/L
|
0.18
mg/L
|
0.06
mg/L
|
6
to 8 mg/L
|
0.24
mg/L
|
0.08
mg/L
|
8
to 10 mg/L
|
0.30
mg/L
|
0.10
mg/L
|
greater
than 10 mg/L
|
0.60
mg/L
|
0.20
mg/L
|
The
30-day average chloride concentration should be used
to determine the appropriate 30-day average nitrite
criterion.
|
Return
to the Table of Contents
Table
3. Maximum Concentration of Total Ammonia Nitrogen for Protection
of
Aquatic Life (mg/L of Nitrogen)
Temperature
(T) in degrees Celcius
pH
|
T
= 0.0
|
T
= 1.0
|
T
= 2.0
|
T
= 3.0
|
T
= 4.0
|
T
= 5.0
|
T
= 6.0
|
6.5
|
27.7
|
28.3
|
27.9
|
27.5
|
27.2
|
26.8
|
26.5
|
6.6
|
27.9
|
27.5
|
27.2
|
26.8
|
26.4
|
26.1
|
25.8
|
6.7
|
26.9
|
26.5
|
26.2
|
25.9
|
25.5
|
25.2
|
24.9
|
6.8
|
25.8
|
25.5
|
25.1
|
24.8
|
24.5
|
24.2
|
23.9
|
6.9
|
24.6
|
24.2
|
23.9
|
23.6
|
23.3
|
23.0
|
22.7
|
7.0
|
23.2
|
22.8
|
22.5
|
22.2
|
21.9
|
21.6
|
21.4
|
7.1
|
21.6
|
21.3
|
20.9
|
20.7
|
20.4
|
20.2
|
19.9
|
7.2
|
19.9
|
19.6
|
19.3
|
19.0
|
18.8
|
18.6
|
18.3
|
7.3
|
18.1
|
17.8
|
17.5
|
17.3
|
17.1
|
16.9
|
16.7
|
7.4
|
16.2
|
16.0
|
15.7
|
15.5
|
15.3
|
15.2
|
15.0
|
7.5
|
14.4
|
14.1
|
14.0
|
13.8
|
13.6
|
13.4
|
13.3
|
7.6
|
12.6
|
12.4
|
12.0
|
11.9
|
11.9
|
11.7
|
11.6
|
7.7
|
10.8
|
10.7
|
10.5
|
10.4
|
10.3
|
10.1
|
10.0
|
7.8
|
9.26
|
9.12
|
8.98
|
8.88
|
8.77
|
8.67
|
8.57
|
7.9
|
7.82
|
7.71
|
7.60
|
7.51
|
7.42
|
7.33
|
7.25
|
8.0
|
6.55
|
6.46
|
6.37
|
6.29
|
6.22
|
6.14
|
6.08
|
8.1
|
5.21
|
5.14
|
5.07
|
5.01
|
4.95
|
4.90
|
4.84
|
8.2
|
4.15
|
4.09
|
4.04
|
3.99
|
3.95
|
3.90
|
3.86
|
8.3
|
3.31
|
3.27
|
3.22
|
3.19
|
3.15
|
3.12
|
3.09
|
8.4
|
2.64
|
2.61
|
2.57
|
2.54
|
2.52
|
2.49
|
2.47
|
8.5
|
2.11
|
2.08
|
2.06
|
2.03
|
2.01
|
1.99
|
1.98
|
8.6
|
1.69
|
1.67
|
1.65
|
1.63
|
1.61
|
1.60
|
1.59
|
8.7
|
1.35
|
1.33
|
1.32
|
1.31
|
1.30
|
1.29
|
1.28
|
8.8
|
1.08
|
1.07
|
1.06
|
1.05
|
1.04
|
1.04
|
1.03
|
8.9
|
0.871
|
0.863
|
0.856
|
0.849
|
0.844
|
0.839
|
0.836
|
9.0
|
0.703
|
0.697
|
0.692
|
0.688
|
0.685
|
0.682
|
0.681
|
Temperature
(T) in degrees Celcius
pH
|
T
= 7.0
|
T
= 8.0
|
T
= 9.0
|
T
= 10.0
|
T
= 11.0
|
T
= 12.0
|
T
= 13.0
|
6.5
|
26.2
|
26.0
|
25.7
|
25.5
|
25.2
|
25.0
|
24.8
|
6.6
|
25.5
|
25.2
|
25.0
|
24.7
|
24.5
|
24.3
|
24.1
|
6.7
|
24.6
|
24.4
|
24.1
|
23.9
|
23.7
|
23.5
|
23.3
|
6.8
|
23.6
|
23.4
|
23.1
|
22.9
|
22.7
|
22.5
|
22.3
|
6.9
|
22.5
|
22.2
|
22.0
|
21.8
|
21.6
|
21.4
|
21.3
|
7.0
|
21.1
|
20.9
|
20.7
|
20.5
|
20.3
|
20.2
|
20.0
|
7.1
|
19.7
|
19.5
|
19.3
|
19.1
|
18.9
|
18.8
|
18.7
|
7.2
|
18.1
|
17.9
|
17.8
|
17.6
|
17.4
|
17.3
|
17.2
|
7.3
|
16.5
|
16.3
|
16.2
|
16.0
|
15.9
|
15.7
|
15.6
|
7.4
|
14.8
|
14.7
|
14.5
|
14.4
|
14.2
|
14.1
|
14.0
|
7.5
|
13.1
|
13.0
|
12.9
|
12.7
|
12.6
|
12.5
|
12.4
|
7.6
|
11.5
|
11.4
|
11.3
|
11.2
|
11.1
|
11.0
|
10.9
|
7.7
|
9.92
|
9.83
|
9.73
|
9.65
|
9.57
|
9.50
|
9.43
|
7.8
|
8.48
|
8.40
|
8.32
|
8.25
|
8.18
|
8.12
|
8.07
|
7.9
|
7.17
|
7.10
|
7.04
|
6.98
|
6.92
|
6.88
|
6.83
|
8.0
|
6.02
|
5.96
|
5.91
|
5.86
|
5.81
|
5.78
|
5.74
|
8.1
|
4.80
|
4.75
|
4.71
|
4.67
|
4.64
|
4.61
|
4.59
|
8.2
|
3.83
|
3.80
|
3.76
|
3.74
|
3.71
|
3.69
|
3.67
|
8.3
|
3.06
|
3.03
|
3.01
|
2.99
|
2.97
|
2.96
|
2.94
|
8.4
|
2.45
|
2.43
|
2.41
|
2.40
|
2.38
|
2.37
|
2.36
|
8.5
|
1.96
|
1.95
|
1.94
|
1.93
|
1.92
|
1.91
|
1.91
|
8.6
|
1.58
|
1.57
|
1.56
|
1.55
|
1.55
|
1.54
|
1.54
|
8.7
|
1.27
|
1.26
|
1.26
|
1.25
|
1.25
|
1.25
|
1.25
|
8.8
|
1.03
|
1.02
|
1.02
|
1.02
|
1.02
|
1.02
|
1.02
|
8.9
|
0.833
|
0.832
|
0.831
|
0.831
|
0.832
|
0.834
|
0.838
|
9.0
|
0.681
|
0.681
|
0.681
|
0.682
|
0.684
|
0.688
|
0.692
|
Temperature
(T) in degrees Celcius
pH
|
T
= 14.0
|
T
= 15.0
|
T
= 16.0
|
T
= 17.0
|
T
= 18.0
|
T
= 19.0
|
T
= 20.0
|
6.5
|
24.6
|
24.5
|
24.3
|
24.2
|
24.0
|
23.9
|
23.8
|
6.6
|
23.9
|
23.8
|
23.6
|
23.5
|
23.3
|
23.3
|
23.2
|
6.7
|
23.1
|
23.0
|
22.8
|
22.7
|
22.6
|
22.5
|
22.4
|
6.8
|
22.2
|
22.0
|
21.9
|
21.8
|
21.7
|
21.6
|
21.5
|
6.9
|
21.1
|
21.0
|
20.8
|
20.7
|
20.6
|
20.5
|
20.4
|
7.0
|
19.9
|
19.7
|
19.6
|
19.5
|
19.4
|
19.3
|
19.2
|
7.1
|
18.5
|
18.4
|
18.3
|
18.2
|
18.1
|
18.0
|
17.9
|
7.2
|
17.1
|
16.9
|
16.8
|
16.8
|
16.7
|
16.6
|
16.5
|
7.3
|
15.5
|
15.4
|
15.3
|
15.2
|
15.2
|
15.1
|
15.1
|
7.4
|
13.9
|
13.9
|
13.8
|
13.7
|
13.6
|
13.6
|
13.5
|
7.5
|
12.4
|
12.3
|
12.2
|
12.2
|
12.1
|
12.1
|
12.0
|
7.6
|
10.8
|
10.8
|
10.7
|
10.7
|
10.6
|
10.6
|
10.5
|
7.7
|
9.37
|
9.31
|
9.26
|
9.22
|
9.18
|
9.15
|
9.12
|
7.8
|
8.02
|
7.97
|
7.93
|
7.90
|
7.87
|
7.84
|
7.82
|
7.9
|
6.79
|
6.75
|
6.72
|
6.69
|
6.67
|
6.65
|
6.64
|
8.0
|
5.71
|
5.68
|
5.66
|
5.62
|
5.61
|
5.60
|
5.74
|
8.1
|
4.56
|
4.54
|
4.53
|
4.51
|
4.50
|
4.49
|
4.49
|
8.2
|
3.65
|
3.64
|
3.63
|
3.62
|
3.61
|
3.61
|
3.61
|
8.3
|
2.93
|
2.92
|
2.92
|
2.91
|
2.91
|
2.91
|
2.91
|
8.4
|
2.36
|
2.35
|
2.35
|
2.35
|
2.35
|
2.35
|
2.36
|
8.5
|
1.90
|
1.90
|
1.90
|
1.90
|
1.90
|
1.91
|
1.92
|
8.6
|
1.54
|
1.54
|
1.54
|
1.55
|
1.56
|
1.56
|
1.57
|
8.7
|
1.25
|
1.25
|
1.26
|
1.26
|
1.27
|
1.28
|
1.29
|
8.8
|
1.02
|
1.03
|
1.03
|
1.04
|
1.05
|
1.06
|
1.07
|
8.9
|
0.842
|
0.847
|
0.853
|
0.861
|
0.870
|
0.880
|
0.891
|
9.0
|
0.698
|
0.704
|
0.711
|
0.720
|
0.729
|
0.740
|
0.752
|
Return
to the Table of Contents
Table
4. Average 30-Day Concentration of Total Ammonia Nitrogen
for Protection of Aquatic Life (mg/L of Nitrogen)
Temperature
(T) in degrees Celcius
pH
|
T
= 0.0
|
T
= 1.0
|
T
= 2.0
|
T
= 3.0
|
T
= 4.0
|
T
= 5.0
|
T
= 6.0
|
6.5
|
2.08
|
2.05
|
2.02
|
1.99
|
1.97
|
1.94
|
1.92
|
6.6
|
2.08
|
2.05
|
2.02
|
1.99
|
1.97
|
1.94
|
1.92
|
6.7
|
2.08
|
2.05
|
2.02
|
1.99
|
1.97
|
1.94
|
1.92
|
6.8
|
2.08
|
2.05
|
2.02
|
1.99
|
1.97
|
1.94
|
1.92
|
6.9
|
2.08
|
2.05
|
2.02
|
1.99
|
1.97
|
1.94
|
1.92
|
7.0
|
2.08
|
2.05
|
2.02
|
1.99
|
1.97
|
1.94
|
1.92
|
7.1
|
2.08
|
2.05
|
2.02
|
1.99
|
1.97
|
1.94
|
1.92
|
7.2
|
2.08
|
2.05
|
2.02
|
1.99
|
1.97
|
1.94
|
1.92
|
7.3
|
2.08
|
2.05
|
2.02
|
1.99
|
1.97
|
1.94
|
1.92
|
7.4
|
2.08
|
2.05
|
2.02
|
2.00
|
1.97
|
1.95
|
1.92
|
7.5
|
2.08
|
2.05
|
2.02
|
2.00
|
1.97
|
1.95
|
1.92
|
7.6
|
2.09
|
2.05
|
2.03
|
2.00
|
1.97
|
1.95
|
1.93
|
7.7
|
2.09
|
2.05
|
2.03
|
2.00
|
1.98
|
1.95
|
1.93
|
7.8
|
1.78
|
1.75
|
1.73
|
1.71
|
1.69
|
1.67
|
1.65
|
7.9
|
1.50
|
1.48
|
1.46
|
1.44
|
1.43
|
1.41
|
1.39
|
8.0
|
1.26
|
1.24
|
1.23
|
1.21
|
1.20
|
1.18
|
1.17
|
8.1
|
1.00
|
0.989
|
0.976
|
0.963
|
0.952
|
0.942
|
0.932
|
8.2
|
0.799
|
0.788
|
0.777
|
0.768
|
0.759
|
0.751
|
0.743
|
8.3
|
0.636
|
0.628
|
0.620
|
0.613
|
0.606
|
0.599
|
0.594
|
8.4
|
0.508
|
0.501
|
0.495
|
0.489
|
0.484
|
0.479
|
0.475
|
8.5
|
0.405
|
0.400
|
0.396
|
0.381
|
0.387
|
0.384
|
0.380
|
8.6
|
0.324
|
0.320
|
0.317
|
0.313
|
0.310
|
0.308
|
0.305
|
8.7
|
0.260
|
0.257
|
0.254
|
0.251
|
0.249
|
0.247
|
0.246
|
8.8
|
0.208
|
0.206
|
0.204
|
0.202
|
0.201
|
0.200
|
0.198
|
8.9
|
0.168
|
0.166
|
0.165
|
0.163
|
0.162
|
0.161
|
0.161
|
9.0
|
0.135
|
0.134
|
0.133
|
0.132
|
0.132
|
0.131
|
0.131
|
Temperature
(T) in degrees Celcius
pH
|
T
= 7.0
|
T
= 8.0
|
T
= 9.0
|
T
= 10.0
|
T
= 11.0
|
T
= 12.0
|
T
= 13.0
|
6.5
|
1.90
|
1.88
|
1.86
|
1.84
|
1.82
|
1.81
|
1.80
|
6.6
|
1.90
|
1.88
|
1.86
|
1.84
|
1.82
|
1.81
|
1.80
|
6.7
|
1.90
|
1.88
|
1.86
|
1.84
|
1.83
|
1.81
|
1.80
|
6.8
|
1.90
|
1.88
|
1.86
|
1.84
|
1.83
|
1.81
|
1.80
|
6.9
|
1.90
|
1.88
|
1.86
|
1.84
|
1.83
|
1.81
|
1.80
|
7.0
|
1.90
|
1.88
|
1.86
|
1.84
|
1.83
|
1.81
|
1.80
|
7.1
|
1.90
|
1.88
|
1.86
|
1.84
|
1.83
|
1.81
|
1.80
|
7.2
|
1.90
|
1.88
|
1.86
|
1.85
|
1.83
|
1.81
|
1.80
|
7.3
|
1.90
|
1.88
|
1.86
|
1.85
|
1.83
|
1.82
|
1.80
|
7.4
|
1.90
|
1.88
|
1.87
|
1.85
|
1.83
|
1.82
|
1.80
|
7.5
|
1.91
|
1.88
|
1.87
|
1.85
|
1.83
|
1.82
|
1.81
|
7.6
|
1.91
|
1.89
|
1.87
|
1.85
|
1.84
|
1.82
|
1.81
|
7.7
|
1.91
|
1.89
|
1.87
|
1.86
|
1.84
|
1.83
|
1.81
|
7.8
|
1.63
|
1.62
|
1.60
|
1.59
|
1.57
|
1.56
|
1.55
|
7.9
|
1.38
|
1.36
|
1.35
|
1.34
|
1.33
|
1.32
|
1.31
|
8.0
|
1.16
|
1.15
|
1.14
|
1.13
|
1.12
|
1.11
|
1.10
|
8.1
|
0.922
|
0.914
|
0.906
|
0.899
|
0.893
|
0.887
|
0.882
|
8.2
|
0.736
|
0.730
|
0.724
|
0.718
|
0.714
|
0.709
|
0.706
|
8.3
|
0.588
|
0.583
|
0.579
|
0.575
|
0.571
|
0.568
|
0.566
|
8.4
|
0.471
|
0.467
|
0.464
|
0.461
|
0.458
|
0.456
|
0.455
|
8.5
|
0.377
|
0.375
|
0.372
|
0.370
|
0.369
|
0.367
|
0.366
|
8.6
|
0.303
|
0.301
|
0.300
|
0.298
|
0.297
|
0.297
|
0.296
|
8.7
|
0.244
|
0.243
|
0.242
|
0.241
|
0.241
|
0.240
|
0.240
|
8.8
|
0.197
|
0.197
|
0.196
|
0.196
|
0.196
|
0.196
|
0.196
|
8.9
|
0.160
|
0.160
|
0.160
|
0.160
|
0.160
|
0.161
|
0.161
|
9.0
|
0.131
|
0.131
|
0.131
|
0.131
|
0.132
|
0.132
|
0.133
|
Temperature
(T) in degrees Celcius
pH
|
T
= 14.0
|
T
= 15.0
|
T
= 16.0
|
T
= 17.0
|
T
= 18.0
|
T
= 19.0
|
T
= 20.0
|
6.5
|
1.78
|
1.77
|
1.64
|
1.52
|
1.41
|
1.31
|
1.22
|
6.6
|
1.78
|
1.77
|
1.64
|
1.52
|
1.41
|
1.31
|
1.22
|
6.7
|
1.78
|
1.77
|
1.64
|
1.52
|
1.41
|
1.31
|
1.22
|
6.8
|
1.78
|
1.77
|
1.64
|
1.52
|
1.42
|
1.32
|
1.22
|
6.9
|
1.78
|
1.77
|
1.64
|
1.53
|
1.42
|
1.32
|
1.22
|
7.0
|
1.79
|
1.77
|
1.64
|
1.53
|
1.42
|
1.32
|
1.22
|
7.1
|
1.79
|
1.77
|
1.65
|
1.53
|
1.42
|
1.32
|
1.23
|
7.2
|
1.79
|
1.78
|
1.65
|
1.53
|
1.42
|
1.32
|
1.23
|
7.3
|
1.79
|
1.78
|
1.65
|
1.53
|
1.42
|
1.32
|
1.23
|
7.4
|
1.79
|
1.78
|
1.65
|
1.53
|
1.42
|
1.32
|
1.23
|
7.5
|
1.80
|
1.78
|
1.66
|
1.54
|
1.43
|
1.33
|
1.23
|
7.6
|
1.80
|
1.79
|
1.66
|
1.54
|
1.43
|
1.33
|
1.24
|
7.7
|
1.80
|
1.79
|
1.66
|
1.54
|
1.44
|
1.34
|
1.24
|
7.8
|
1.54
|
1.53
|
1.42
|
1.32
|
1.23
|
1.14
|
1.07
|
7.9
|
1.31
|
1.30
|
1.21
|
1.12
|
1.04
|
0.970
|
0.904
|
8.0
|
1.10
|
1.09
|
1.02
|
0.944
|
0.878
|
0.818
|
0.762
|
8.1
|
0.878
|
0.874
|
0.812
|
0.756
|
0.704
|
0.655
|
0.611
|
8.2
|
0.703
|
0.700
|
0.651
|
0.606
|
0.565
|
0.527
|
0.491
|
8.3
|
0.564
|
0.562
|
0.523
|
0.487
|
0.455
|
0.424
|
0.396
|
8.4
|
0.453
|
0.452
|
0.421
|
0.393
|
0.367
|
0.343
|
0.321
|
8.5
|
0.366
|
0.365
|
0.341
|
0.318
|
0.298
|
0.278
|
0.261
|
8.6
|
0.296
|
0.296
|
0.277
|
0.259
|
0.242
|
0.227
|
0.213
|
8.7
|
0.241
|
0.241
|
0.226
|
0.212
|
0.198
|
0.186
|
0.175
|
8.8
|
0.197
|
0.198
|
0.185
|
0.174
|
0.164
|
0.154
|
0.145
|
8.9
|
0.162
|
0.163
|
0.153
|
0.144
|
0.136
|
0.128
|
0.121
|
9.0
|
0.134
|
0.135
|
0.128
|
0.121
|
0.114
|
0.108
|
0.102
|
1.
The average of the measured values must be less than
the average of the corresponding individual values.
2.
Each measured value is compared to the corresponding
individual values. No more than one in five of
the measured values can be greater than 1.5 x the
corresponding criteria values.
|
Return to the Table of Contents
Preface
The
MINISTRY OF ENVIRONMENT, LANDS AND PARKS (now called Ministry
of Water, Land and Air Protection) develops province-wide ambient
water quality guidelines for variables that are important in
the surface waters of British Columbia. This work has the following
goals:
- to
provide guidelines for the evaluation of data on water, sediment
and biota
- to provide
guidelines for the establishment of site-specific ambient
water quality objectives
Ambient
water quality objectives for specific waterbodies will be based
on the guidelines and also consider present and future uses,
waste discharges, hydrology/limnology/oceanography, and existing
background water quality. The process for establishing water
quality objectives is more fully outlined in Principles
for Preparing Water Quality Objectives in British Columbia, copies
of which are available from the Water Quality Section of the
Environmental Quality Branch.
Neither
guidelines nor objectives which are derived from them, have
any legal standing. The objectives, however, can be used to
calculate allowable limits or levels for contaminants in waste
discharges. These limits are set out in waste management permits
and thus have legal standing. The objectives are not usually
incorporated as conditions of the permit.
The definition
adopted for a guideline is:
A
maximum and/or a minimum value for a physical, chemical
or biological characteristic of water, sediment or
biota, which should not be exceeded to prevent specified
detrimental effects from occurring to a water use,
including aquatic life, under specified environmental
conditions.
|
The guidelines
are province-wide in application, are use-specific, and are
developed for some or all of the following specific water uses:
- raw drinking,
public water supply and food processing
- aquatic
life and wildlife
- agriculture
(livestock watering and irrigation)
- recreation
and aesthetics
- industrial
(water supplies)
The guidelines are set after considering the scientific literature, guidelines
from other jurisdictions, and general conditions in British Columbia. The
scientific literature gives information on the effects of toxicants on
various life forms. This information is not always conclusive because it
is usually based on laboratory work which, at best, only approximates actual
field conditions. To compensate for this uncertainty, guidelines have built-in
safety factors which are conservative but reflect natural background conditions
in the province.
The site-specific
water quality objectives are, in most cases, the same as guidelines.
However, in some cases, such as when natural background levels
exceed the guidelines, the objectives could be less stringent
than the guidelines. In relatively rare instances, for example
if the resource is unusually valuable or of special provincial
significance, the safety factor could be increased by using
objectives which are more stringent than the guidelines. Another
approach in such special cases is to develop site-specific
guidelines by carrying out toxicity experiments in the field.
This approach is costly and time-consuming and therefore seldom
used.
Guidelines
are subject to review and revision as new information becomes
available, or as other circumstances dictate.
The
guidelines apply to the ambient raw water source
before it is diverted or treated for domestic use.
The
Ministry of Health regulates the quality of water
for domestic use after it is treated and delivered
by a water purveyor.
Guidelines
relating to public health at bathing beaches are
the same as those used by the Ministry of Health
which regulates the recreation and aesthetic use.
|
Return to the Table of Contents
Recommended
Guidelines
These criteria are
based on a detailed analysis given in a technical document and
are summarized in the Tables. The criteria are consistent with
the Canadian Water Quality Guidelines (CCREM Guidelines) issued
by the Canadian Council of Resource and Environment Ministers
(1986), except as noted.
Nitrate,
nitrite, and ammonia are the major inorganic nitrogen compounds
occurring in surface waters. There is little environmental
information on other compounds, both inorganic and organic,
which are minor constituents or do not appear to affect water
uses. These are therefore not included in the report at this
time.
Drinking Water (Includes Food Processing Water)
For drinking
water, high nitrate concentrations have been identified as
a problem for infants. Nitrate can be converted to nitrite
which combines with hemoglobin in the blood to form methemoglobin
which does not absorb oxygen. With reduced capacity of the
blood to absorb oxygen, death from lack of oxygen can result.
Many agencies have specified maximum acceptable concentrations
for nitrate or nitrate plus nitrite in drinking water and there
is a general consensus that 10 mg/L (as N) represents a level
of adequate protection. This well established level is proposed
as the criterion for nitrate in drinking water for British
Columbia.
The
criterion for British Columbia which is proposed
is a maximum of 10 mg/L nitrate + nitrite (as N).
|
There is also a general consensus with regard to nitrite among other agencies,
and no recent scientific evidence to the contrary, that less than 1 mg/L
nitrite (as N) represents a concentration which will provide protection
against adverse effects in humans in drinking water supplies.
The
criterion for British Columbia which is proposed
is a maximum of 1 mg/L nitrate + nitrite (as N).
|
Establishing a criterion for ammonia in drinking water is more difficult. Although
a number of other agencies have specified ammonia concentrations intended
to provide acceptable drinking water, there now seems to be a very poor basis
for the concentrations proposed. There does not seem to be sufficient data
to define an ammonia concentration at which problems such as taste and odour,
interference with chlorine disinfection, or any health effects occur. Consequently,
no criterion for ammonia in drinking water supplies is proposed.
Aquatic Life (Freshwater, Marine and Estuarine)
In the literature,
there has been a much more detailed examination of the response
to nitrate, nitrite, and ammonia by freshwater biota, particularly
fish, than by marine biota. Studies concerning estuarine biota
are almost totally absent. As a consequence, the data on which
to base criteria are much better for freshwater than marine
water. Since virtually no data exist for nitrogen toxicity
in estuarine environments, no specific criteria are suggested.
It is proposed that the more stringent of freshwater and marine
criteria should be used for estuaries. For these criteria the
maximum concentration is designed to protect aquatic life against
acutely toxic effects and the 30-day average against chronic
effects. The 30-day average should be calculated from at least
five weekly samples.
For freshwater
studies there has been different amounts of research into the
aquatic toxicology of the three forms of nitrogen. Nitrate
has been the subject of few investigations due to its relatively
low toxicity.
Return to the Table of Contents
Based
on the information available, a criterion of 200
mg/L nitrate (as N) is recommended as a maximum concentration
and 40 mg/L nitrate (as N) as a 30-day average.
|
There are no CCREM Guidelines for nitrate for freshwater aquatic life.
Nitrite
has been shown to be quite toxic to some groups of fish, particularly
salmonids, and consequently more investigations have been done.
On
the basis of literature reports, a criterion of 0.020
mg/L (as N) is recommended as a mean concentration
over a 30-day period for low chloride water, and
a maximum concentration of 0.060 mg/L (as N) is recommended.
|
Allowable concentrations increase with ambient concentrations of chloride,
as shown in the Tables. The CCREM Guidelines specify
a maximum of 0.06 mg/L for all chloride concentrations. The recommended
criteria vary with chloride concentration to reflect the marked influence
of chloride on nitrite toxicity, and average criteria have also been recommended
to provide adequate protection to the salmonids prevalent in British Columbia,
particularly at low chloride concentrations.
Ammonia
has been the subject of intensive investigation and there is
thus an excellent background on which to base a criterion.
Because ammonia has been investigated for a long period, increasingly
sophisticated and accurate criteria are being derived. Ammonia
criteria have evolved from a single value to tabular criteria
relating toxicity to important physical or other interactive
factors which affect toxicity. Two factors which are important
to the toxicity of ammonia to aquatic organisms are the pH
and temperature of the water environment. The pH and temperature
affect the amount of un-ionized ammonia which is the form most
toxic to aquatic life.
Return to the Table of Contents
The Tables give
the criteria recommended for maximum allowable concentrations
of ammonia and for longer-term (30 day) allowable
concentrations.
|
These criteria are similar to those developed by the US Environmental Protection
Agency (EPA). The CCREM Guidelines adopted the EPA average criteria as
maximum values, which in British Columbia's opinion is unnecessarily restrictive.
For marine
studies, less information is available on which to base criteria.
For nitrate and nitrite, insufficient data are available to
propose any criteria.
NOTE: The marine ammonia criteria found in this document have been replaced
by newer values found in the document Ambient
Water Quality Guidelines for Ammonia to Protect Marine Aquatic Life.
For
ammonia, a maximum concentration of 2.5 mg/L (as
N) and a 30 day average concentration of 1.0 mg/L
(as N) are recommended.
|
There are no CCREM Guidelines for marine aquatic life. For estuarine conditions,
the freshwater criteria apply. Increasing salinity decreases ammonia toxicity
to a slight degree so some marginal additional protection is afforded.
Irrigation and Livestock Watering
Water with
excessive amounts of ammonia may affect agricultural uses such
as irrigation or water supplied to livestock. Insufficient
information is available to establish a criterion for nitrogen
in irrigation water since an allowable concentration would
be dependent on soil type, irrigation rate, and other factors.
The proposed criteria for livestock watering exclude ammonia
since few data exist.
For
nitrate or nitrate plus nitrite, a maximum concentration
of 100 mg/L (as N) is recommended and for nitrite
alone a maximum of
10 mg/L (as N). The same concentrations are recommended for waters which
might be used by wildlife as a drinking water supply.
|
There are no CCREM Guidelines for wildlife.
Recreation and Aesthetics
This is
a water use for which high concentrations of nitrate, nitrite
or ammonia are not likely to cause any direct problems in terms
of body contact or visual deterioration. The more likely problem
would be eutrophication-related problems when high concentrations
of nitrogen (and accompanying phosphorus) cause heavy accumulations
of algae. However, to protect recreational users who may ingest
water, it is recommended that the drinking water criteria should
apply to waters used for recreation.
The
criteria for British Columbia which is proposed is
a maximum of 10 mg/L nitrate + nitrite (as N). The
criterion for British Columbia which is proposed
is a maximum of 1 mg/L nitrite (as N).
|
There are no CCREM Guidelines for nitrogen for recreation.
Return to the Table of Contents
Application
of Guidelines
Most of
the criteria proposed require no additional explanation for
their use. However, the table of ammonia criteria values for
evaluation of chronic toxicity does require additional explanation
for its application. The designated sampling period is 30 days
and it is intended that at least five samples would be obtained.
In addition to ammonia, each sample must be measured for pH
and temperature. The temperature is that of the water in the
field, and the pH is the laboratory pH at the time of analysis,
although field pH is also acceptable if truly accurate measurements
can be obtained.
The average
measured concentration is calculated as an arithmetic mean.
Using the individual temperature and pH values, the corresponding
criteria values are obtained from the table. A mean of these
criteria values is compared to the mean of the measured ammonia
values. If the mean value for measured total ammonia exceeds
the mean criteria value, the criteria would then be considered
to be exceeded. If the mean value does not exceed the mean
criteria value, it is still necessary to compare individual
criteria to corresponding analytical results to ascertain whether
or not more than 20% of the measured values exceed the mean
criteria value by more than 150%. If more than 20% of the measured
values do exceed the mean criteria by 150%, the criteria is
exceeded even if the measured mean is less than the mean criteria
value. This provision restricts the occurrence of fluctuating
concentrations which can be more detrimental to aquatic life
than a steady concentration.
Return to the Table of Contents
