Wyoming Administrative Code › Agency 020 - Environmental Quality, Dept. of › Sub-Agency 0011 - Water Quality › Chapter 1 - WYOMING SURFACE WATER QUALITY STANDARDS › Appendix C - Ammonia Toxicity Criteria

Current through July 13, 2024
(a) The ammonia values in the tables below are expressed in
				  milligrams ammonia nitrogen per liter (mg N/L) and vary with temperature and/or
				  pH, fish species or fish life stage. The ammonia criteria for pH values not
				  represented in the tables can be calculated using the formulas in section (b)
				  of Appendix C.
(i) pH-Dependent Values of the Acute Criterion
				  (CMC)(1) for Ammonia
Acute Values, (mg N/L)
pH
Salmonids
						  Present
Salmonids Absent
6.5
32.6
48.8
6.6
31.3
46.8
6.7
29.8
44.6
6.8
28.1
42.0
6.9
26.2
39.1
7.0
24.1
36.1
7.1
22.0
32.8
7.2
19.7
29.5
7.3
17.5
26.2
7.4
15.4
23.0
7.5
13.3
19.9
7.6
11.4
17.0
7.7
9.65
14.4
7.8
8.11
12.1
7.9
6.77
10.1
8.0
5.62
8.40
8.1
4.64
6.95
8.2
3.83
5.72
8.3
3.15
4.71
8.4
2.59
3.88
8.5
2.14
3.20
8.6
1.77
2.65
8.7
1.47
2.20
8.8
1.23
1.84
8.9
1.04
1.56
9.0
0.885
1.32
(ii) Temperature and pH Dependent Values of the Chronic
				  Criterion (CCC)(2) for Ammonia, Fish Early Life
				  Stages
Present
Temperature
						  (oC)
pH
0
14
16
18
20
22
24
26
28
30
6.5
6.67
6.67
6.06
5.33
4.68
4.12
3.62
3.18
2.80
2.46
6.6
6.57
6.57
5.97
5.25
4.61
4.05
3.56
3.13
2.75
2.42
6.7
6.44
6.44
5.86
5.15
4.52
3.98
3.50
3.07
2.70
2.37
6.8
6.29
6.29
5.72
5.03
4.42
3.89
3.42
3.00
2.64
2.32
6.9
6.12
6.12
5.56
4.89
4.30
3.78
3.32
2.92
2.57
2.25
7.0
5.91
5.91
5.37
4.72
4.15
3.65
3.21
2.82
2.48
2.18
7.1
5.67
5.67
5.15
4.53
3.98
3.50
3.08
2.70
2.38
2.09
7.2
5.39
5.39
4.90
4.31
3.78
3.33
2.92
2.57
2.26
1.99
7.3
5.08
5.08
4.61
4.06
3.57
3.13
2.76
2.42
2.13
1.87
7.4
4.73
4.73
4.30
3.78
3.32
2.92
2.57
2.26
1.98
1.74
7.5
4.36
4.36
3.97
3.49
3.06
2.69
2.37
2.08
1.83
1.61
7.6
3.98
3.98
3.61
3.18
2.79
2.45
2.16
1.90
1.67
1.47
7.7
3.58
3.58
3.25
2.86
2.51
2.21
1.94
1.71
1.50
1.32
7.8
3.18
3.18
2.89
2.54
2.23
1.96
1.73
1.52
1.33
1.17
7.9
2.80
2.80
2.54
2.24
1.96
1.73
1.52
1.33
1.17
1.03
8.0
2.43
2.43
2.21
1.94
1.71
1.50
1.32
1.16
1.02
0.897
8.1
2.10
2.10
1.91
1.68
1.47
1.29
1.14
1.00
0.879
0.773
8.2
1.79
1.79
1.63
1.43
1.26
1.11
0.973
0.855
0.752
0.661
8.3
1.52
1.52
1.39
1.22
1.07
0.941
0.827
0.727
0.639
0.562
8.4
1.29
1.29
1.17
1.03
0.906
0.796
0.700
0.615
0.541
0.475
8.5
1.09
1.09
0.990
0.870
0.765
0.672
0.591
0.520
0.457
0.401
8.6
0.920
0.920
0.836
0.735
0.646
0.568
0.499
0.439
0.386
0.339
8.7
0.778
0.778
0.707
0.622
0.547
0.480
0.422
0.371
0.326
0.287
8.8
0.661
0.661
0.601
0.528
0.464
0.408
0.359
0.315
0.277
0.244
8.9
0.565
0.565
0.513
0.451
0.397
0.349
0.306
0.269
0.237
0.208
9.0
0.486
0.486
0.442
0.389
0.342
0.300
0.264
0.232
0.204
0.179
(iii) Temperature and pH Dependent Values of the Chronic
				  Criterion (CCC)(2) for Ammonia, Fish Early Life
				  Stages
Absent
Temperature
						  (oC)
pH
0-7
8
9
10
11
12
13
14
15*
16*
6.5
10.8
10.1
9.51
8.92
8.36
7.84
7.35
6.89
6.46
6.06
6.6
10.7
9.99
9.37
8.79
8.24
7.72
7.24
6.79
6.36
5.97
6.7
10.5
9.81
9.20
8.62
8.08
7.58
7.11
6.66
6.25
5.86
6.8
10.2
9.58
8.98
8.42
7.90
7.40
6.94
6.51
6.10
5.72
6.9
9.93
9.31
8.73
8.19
7.68
7.20
6.75
6.33
5.93
5.56
7.0
9.60
9.00
8.43
7.91
7.41
6.95
6.52
6.11
5.73
5.37
7.1
9.20
8.63
8.09
7.58
7.11
6.67
6.25
5.86
5.49
5.15
7.2
8.75
8.20
7.69
7.21
6.76
6.34
5.94
5.57
5.22
4.90
7.3
8.24
7.73
7.25
6.79
6.37
5.97
5.60
5.25
4.92
4.61
7.4
7.69
7.21
6.76
6.33
5.94
5.57
5.22
4.89
4.59
4.30
7.5
7.09
6.64
6.23
5.84
5.48
5.13
4.81
4.51
4.23
3.97
7.6
6.46
6.05
5.67
5.32
4.99
4.68
4.38
4.11
3.85
3.61
7.7
5.81
5.45
5.11
4.79
4.49
4.21
3.95
3.70
3.47
3.25
7.8
5.17
4.84
4.54
4.26
3.99
3.74
3.51
3.29
3.09
2.89
7.9
4.54
4.26
3.99
3.74
3.51
3.29
3.09
2.89
2.71
2.54
8.0
3.95
3.70
3.47
3.26
3.05
2.86
2.68
2.52
2.36
2.21
8.1
3.41
3.19
2.99
2.81
2.63
2.47
2.31
2.17
2.03
1.91
8.2
2.91
2.73
2.56
2.40
2.25
2.11
1.98
1.85
1.74
1.63
8.3
2.47
2.32
2.18
2.04
1.91
1.79
1.68
1.58
1.48
1.39
8.4
2.09
1.96
1.84
1.73
1.62
1.52
1.42
1.33
1.25
1.17
8.5
1.77
1.66
1.55
1.46
1.37
1.28
1.20
1.13
1.06
0.990
8.6
1.49
1.40
1.31
1.23
1.15
1.08
1.01
0.951
0.892
0.836
8.7
1.26
1.18
1.11
1.04
0.976
0.915
0.858
0.805
0.754
0.707
8.8
1.07
1.01
0.944
0.885
0.829
0.778
0.729
0.684
0.641
0.601
8.9
0.917
0.860
0.806
0.756
0.709
0.664
0.623
0.584
0.548
0.513
9.0
0.790
0.740
0.694
0.651
0.610
0.572
0.536
0.503
0.471
0.442
*At 15 
				  oC and above, the criterion for fish
				  early life stages absent is the same as the criterion for fish early life
				  stages present.
(b) For pH values not expressed in the tables above, ammonia
				  toxicity criteria can be calculated as follows:
(i) Criterion maximum concentration (CMC) when salmonids or
				  other sensitive cold water species are present:
Click here to view
				  image
(ii) Criterion maximum concentration (CMC) when salmonids or
				  other sensitive cold water species are absent:
Click here to view
				  image
(iii) Criterion continuous concentration (CCC) when fish
				  early life stages are present:
Click here to view
				  image
(iv) Criterion continuous concentration (CCC) when fish early
				  life stages are absent:
Click here to view
				  image
(1)Criterion maximum concentration
				  (CMC) refers to the one-hour average concentration of total ammonia nitrogen
				  (mg N/L) not to be exceeded more than once every three (3) years. The CMC can
				  also be referred to as the acute value.
(2)Criterion continuous concentration
				  (CCC) refers to the 30-day average concentration of total ammonia nitrogen (mg
				  N/L) not to be exceeded more than once every three (3) years. In addition, the
				  highest 4-day average within the 30-day period should not exceed 2.5 times the
				  CCC. The CCC can also be referred to as the chronic value. The CCC values are
				  implemented on Class 2 waters with an assumption that early life stages of fish
				  are present. This assumption can be rebutted, but only where a permittee,
				  discharge permit applicant or affected party provides sufficient site-specific
				  information to support a conclusion that the assumption is not appropriate for
				  that water body.