Nitrate Contamination

Nitrate in Idaho Drinking Water

Ranked by nitrate violation count · Data from EPA SDWIS & UCMR

124

Cities Tested

124

Has Violations

100%

% Has Violations

13.6 violations

State Avg

▼ 0% vs national

vs National

134

Health Violations

Analysis

Nitrate in Idaho: what the data shows

Idaho has 124 cities with nitrate-related violations. The EPA MCL for nitrate is 10 mg/L (measured as nitrogen). The state has 124 cities with at least one nitrate violation. Nitrate is the most common groundwater contaminant in the United States. It enters water supplies primarily through agricultural fertilizer runoff, septic system leaching, and animal feedlot operations. Rural and agricultural communities face the highest risk. The primary acute health concern is methemoglobinemia ("blue baby syndrome") in infants under six months. Emerging research also links chronic nitrate exposure to thyroid disease, certain cancers, and adverse birth outcomes. Reverse osmosis, ion exchange, and distillation can remove nitrate from drinking water — standard carbon filters do not.

Comparison

Cities exceeding 10 mg/L EPA MCL

Idaho

100%

124 of 124 cities

← = Exactly at national rate

National avg

100%

8001 of 8001 cities

City Map

Nitrate data across Idaho

Each dot is a city with nitrate violation data. Cities with at least one nitrate-related violation are highlighted. Size reflects population served.

Worst Offenders

Top 10 cities by nitrate level in Idaho

Highest Nitrate levels (violations)

All Cities

All Idaho cities ranked by nitrate level

#	City	Level	Violations?	Violations	Grade
1	Nampa	128 violations	Yes	255	F
2	Caldwell	107 violations	Yes	226	F
3	Boise	101 violations	Yes	218	F
4	Ammon	67 violations	Yes	52	D+
5	Idaho Falls	55 violations	Yes	101	D
6	Rathdrum	51 violations	Yes	79	D
7	Preston	41 violations	Yes	82	F
8	Pocatello	38 violations	Yes	117	F
9	Sandpoint	38 violations	Yes	328	F
10	Coeur D'Alene	36 violations	Yes	87	D
11	Mountain Home	33 violations	Yes	55	D
12	Coeur D Alene	31 violations	Yes	125	F
13	Eagle	31 violations	Yes	52	F
14	Garden Valley	30 violations	Yes	109	D
15	Lewiston	28 violations	Yes	91	F
16	Bonners Ferry	28 violations	Yes	516	D
17	Sagle	27 violations	Yes	39	D
18	Ketchum	26 violations	Yes	34	D
19	Plummer	26 violations	Yes	24	F
20	Twin Falls	25 violations	Yes	71	D+
21	Lapwai	24 violations	Yes	48	D+
22	Ashton	24 violations	Yes	29	A-
23	Notus	24 violations	Yes	37	C
24	Athol	23 violations	Yes	67	D+
25	Blackfoot	22 violations	Yes	85	F
26	Mountain Home Afb	22 violations	Yes	17	D
27	New Plymouth	20 violations	Yes	64	D+
28	Hayden	18 violations	Yes	56	D
29	Kamiah	18 violations	Yes	127	D
30	Middleton	17 violations	Yes	64	D+
31	Kuna	15 violations	Yes	98	D
32	Rigby	15 violations	Yes	28	D
33	Challis	14 violations	Yes	8	B
34	Shelley	13 violations	Yes	44	D
35	Troy	13 violations	Yes	19	C+
36	Post Falls	12 violations	Yes	56	D
37	Rexburg	12 violations	Yes	83	F
38	Payette	12 violations	Yes	8	B
39	Mccall	12 violations	Yes	19	F
40	Burley	11 violations	Yes	29	F
41	Emmett	11 violations	Yes	31	D
42	Sun Valley	11 violations	Yes	13	D
43	Coolin	11 violations	Yes	2	B+
44	Rupert	10 violations	Yes	5	D+
45	Grace	10 violations	Yes	14	B-
46	Buhl	9 violations	Yes	65	D
47	Heyburn	9 violations	Yes	28	D
48	Victor	9 violations	Yes	6	B-
49	Worley	9 violations	Yes	24	F
50	Greenleaf	9 violations	Yes	4	A
51	Meridian	8 violations	Yes	34	F
52	St Maries	8 violations	Yes	17	B-
53	Driggs	8 violations	Yes	12	D+
54	Fernwood	8 violations	Yes	103	B
55	Idaho City	8 violations	Yes	20	B-
56	Juliaetta	8 violations	Yes	22	D
57	Chubbuck	7 violations	Yes	16	C+
58	Jerome	7 violations	Yes	22	D
59	Franklin	7 violations	Yes	13	C+
60	Kellogg	7 violations	Yes	90	C+
61	Spirit Lake	7 violations	Yes	26	D+
62	Salmon	7 violations	Yes	43	D
63	Marsing	7 violations	Yes	29	D+
64	Garden City	6 violations	Yes	12	C-
65	Kimberly	6 violations	Yes	10	B+
66	Gooding	6 violations	Yes	13	B+
67	Sugar City	6 violations	Yes	16	A
68	Ovid	6 violations	Yes	2	B+
69	Hope	6 violations	Yes	1	A-
70	Moscow	5 violations	Yes	20	C-
71	Fruitland	5 violations	Yes	120	D
72	Orofino	5 violations	Yes	107	D
73	St Anthony	5 violations	Yes	25	D
74	Homedale	5 violations	Yes	21	B+
75	Iona	5 violations	Yes	23	A-
76	Ucon	5 violations	Yes	7	D+
77	Blanchard	5 violations	Yes	3	A-
78	Carey	5 violations	Yes	5	A-
79	Hazelton	5 violations	Yes	8	B
80	Donnelly	5 violations	Yes	6	B
81	Hailey	4 violations	Yes	7	C
82	American Falls	4 violations	Yes	36	F
83	Wilder	4 violations	Yes	3	A
84	Soda Springs	4 violations	Yes	20	C+
85	Grangeville	4 violations	Yes	27	B-
86	Wendell	4 violations	Yes	6	A
87	Priest River	4 violations	Yes	76	B
88	Cottonwood	4 violations	Yes	26	B+
89	Moyie Springs	4 violations	Yes	18	B
90	Roberts	4 violations	Yes	7	A-
91	Star	3 violations	Yes	0	A
92	Wallace	3 violations	Yes	6	A-
93	Malad	3 violations	Yes	5	A
94	Oakley	3 violations	Yes	37	D
95	Kingston	3 violations	Yes	16	A-
96	Genesee	3 violations	Yes	8	A-
97	Horseshoe Bend	3 violations	Yes	77	C-
98	Clark Fork	3 violations	Yes	3	A-
99	Ririe	3 violations	Yes	8	A-
100	Melba	3 violations	Yes	16	B+
101	Old Town	3 violations	Yes	0	B+
102	Filer	2 violations	Yes	34	B-
103	Fort Hall	2 violations	Yes	5	D
104	Pinehurst	2 violations	Yes	0	A-
105	Hauser	2 violations	Yes	12	A
106	Paul	2 violations	Yes	4	A
107	Arco	2 violations	Yes	12	A-
108	Cascade	2 violations	Yes	5	B+
109	Inkom	2 violations	Yes	13	B+
110	Mccammon	2 violations	Yes	8	A-
111	Downey	2 violations	Yes	2	A
112	Riggins	2 violations	Yes	8	A-
113	Craigmont	2 violations	Yes	12	A
114	Weiser	1 violations	Yes	0	A-
115	Montpelier	1 violations	Yes	6	A-
116	Bellevue	1 violations	Yes	28	D
117	Dalton Gardens	1 violations	Yes	6	A
118	Glenns Ferry	1 violations	Yes	3	A-
119	Hagerman	1 violations	Yes	3	A
120	Teton	1 violations	Yes	5	A
121	Mackay	1 violations	Yes	7	A
122	Dayton	1 violations	Yes	20	B
123	Paris	1 violations	Yes	3	B+
124	Dubois	1 violations	Yes	3	A

FAQ

Frequently asked questions about nitrate in Idaho

Is nitrate in Idaho tap water dangerous?

Yes — 124 cities in Idaho have nitrate-related violations. The EPA MCL is 10 mg/L. Nitrate is especially dangerous for infants under six months, where it can cause methemoglobinemia ("blue baby syndrome"). Adults face lower acute risk, but chronic exposure is linked to thyroid disease and certain cancers.

How can I remove nitrate from my drinking water?

Reverse osmosis, ion exchange, and distillation are effective at removing nitrate. Standard carbon filters (including most pitcher and faucet-mount filters) do NOT remove nitrate. If you rely on a private well in an agricultural area, have your water tested annually for nitrate.

What causes high nitrate levels in Idaho water?

Nitrate contamination comes primarily from agricultural fertilizer runoff, septic system leaching, and animal feedlot operations. Rural communities near intensive farming are most at risk. Shallow wells are particularly vulnerable. Heavy rainfall can spike nitrate levels as it washes fertilizer into groundwater and surface water supplies.

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