Nev. Admin. Code § 445A.118 - Water quality criteria for total ammonia

1. The acute criteria of water quality with regard to the concentration of total ammonia are subject to the following:

(a) The 1-hour average concentration of total ammonia, in milligrams of nitrogen per liter, for the protection of freshwater aquatic life is shown in Table 1.

(b) For cold-water fisheries, the concentration of total ammonia, in milligrams of nitrogen per liter, must not exceed the applicable acute criterion listed under "Cold-Water Fisheries" set forth in Table 1, more than once every 3 years on average.

(c) For warm-water fisheries, the concentration of total ammonia, in milligrams of nitrogen per liter, must not exceed the applicable acute criterion listed under "Warm-Water Fisheries" set forth in Table 1, more than once every 3 years on average.

2. The chronic criteria of water quality with regard to the concentration of total ammonia are subject to the following:

(a) The 30-day average concentration of total ammonia, in milligrams of nitrogen per liter, for the protection of freshwater aquatic life is shown in Tables 2 and 3.

(b) The concentration of total ammonia, in milligrams of nitrogen per liter, expressed as a 30-day average must not exceed the applicable chronic criterion listed in Tables 2 and 3 more than once every 3 years on average, and the highest 4-day average within the 30-day period must not exceed 2.5 times the applicable chronic criterion.

(c) Table 3 must not be used unless the Division receives acceptable documentation of the absence of freshwater fish in early life stages.

TABLE 1: ACUTE WATER QUALITY CRITERIA FOR TOTAL AMMONIA FOR FRESHWATER AQUATIC LIFE (mg nitrogen/l)
pH	Cold-Water Fisheries1	Warm-Water Fisheries2
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

¹ The acute water quality criteria for total ammonia for cold-water fisheries were calculated using the following equation, which may also be used to calculate unlisted values:

Acute water quality criteria for ammonia (cold-water fisheries) =

Click here to view image.

² The acute water quality criteria for total ammonia for warm-water fisheries were calculated using the following equation, which may also be used to calculate unlisted values:

Acute water quality criteria for ammonia (warm-water fisheries) =

Click here to view image.

TABLE 2: CHRONIC WATER QUALITY CRITERIA FOR TOTAL AMMONIA FOR WATERS WHERE FRESHWATER FISH IN EARLY LIFE STAGES MAY BE PRESENT (mg nitrogen/l)1
pH	Temperature (°C)
	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

¹ The chronic water quality criteria for total ammonia for waters where freshwater fish in early life stages may be present were calculated using the following equation, which may also be used to calculate unlisted values:

Chronic water quality criteria for ammonia (fish in early life stages present) =

Click here to view image.

where:

T=°C

x means multiplication

MIN means the lesser of the two values separated by the comma

TABLE 3: CHRONIC WATER QUALITY CRITERIA FOR TOTAL AMMONIA FOR WATERS WHERE FRESHWATER FISH IN EARLY LIFE STAGES ARE ABSENT (mg nitrogen/l)1
pH	Temperature (°C)
	0-7	8	9	10	11	12	13	14	152		162
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

¹ The chronic water quality criteria for total ammonia for waters where freshwater fish in early life stages are absent were calculated using the following equation, which may also be used to calculate unlisted values:

Chronic water quality criteria for ammonia (fish in early life stages absent) =

Click here to view image.

where:

T=°C

x means multiplication

MAX means the greater of the two values separated by the comma

² At 15°C and above, the criteria for waters where freshwater fish in early life stages are absent is the same as the criteria for waters where freshwater fish in early life stages may be present.

NOTES FOR TABLES 1, 2 AND 3:

- pH and temperature are field measurements that must be taken at the same time and location as the water sample destined for the laboratory analysis of ammonia.

- If the field-measured pH or the temperature values, or both, fall between the tabular values set forth in this section, the field-measured values or temperature values, as appropriate, must be rounded according to standard rounding procedures to the nearest tabular value to determine the applicable ammonia standard, or the equations provided in this section may be used to calculate unlisted values.

Notes

Nev. Admin. Code § 445A.118

Added to NAC by Environmental Comm'n by R099-02, eff. 12-17-2002

NRS 445A.425, 445A.520