Nitrate Contamination

Nitrate in Colorado Drinking Water

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

161

Cities Tested

161

Has Violations

100%

% Has Violations

6.8 violations

State Avg

▼ 0% vs national

vs National

206

Health Violations

Analysis

Nitrate in Colorado: what the data shows

Colorado has 161 cities with nitrate-related violations. The EPA MCL for nitrate is 10 mg/L (measured as nitrogen). The state has 161 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

Colorado

100%

161 of 161 cities

← = Exactly at national rate

National avg

100%

8001 of 8001 cities

City Map

Nitrate data across Colorado

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 Colorado

Highest Nitrate levels (violations)

All Cities

All Colorado cities ranked by nitrate level

#	City	Level	Violations?	Violations	Grade
1	Burlington	89 violations	Yes	84	C-
2	Colorado Springs	49 violations	Yes	117	F
3	Durango	42 violations	Yes	112	F
4	Windsor	35 violations	Yes	51	D
5	Divide	32 violations	Yes	49	F
6	Denver	31 violations	Yes	104	F
7	Carbondale	31 violations	Yes	77	F
8	Falcon	28 violations	Yes	1	D
9	Towoac	26 violations	Yes	5	D
10	Aurora	22 violations	Yes	22	F
11	South Fork	18 violations	Yes	8	D
12	Steamboat Springs	17 violations	Yes	57	F
13	Silt	17 violations	Yes	28	F
14	Woodland Park	16 violations	Yes	55	D
15	Glenwood Springs	14 violations	Yes	17	F
16	Fort Lupton	14 violations	Yes	35	D
17	Calhan	14 violations	Yes	3	D+
18	Perth (T)	14 violations	Yes	2	D+
19	Granby	13 violations	Yes	9	C-
20	Pueblo	12 violations	Yes	15	F
21	Frisco	12 violations	Yes	7	F
22	Englewood	11 violations	Yes	33	D
23	Crested Butte	11 violations	Yes	12	C-
24	Lakewood	10 violations	Yes	28	F
25	Castle Rock	10 violations	Yes	20	F
26	La Junta	10 violations	Yes	245	F
27	Bayfield	10 violations	Yes	25	D
28	Wiggins	10 violations	Yes	16	D+
29	Crawford	10 violations	Yes	31	F
30	Brighton	9 violations	Yes	18	F
31	Silverthorne	9 violations	Yes	3	D+
32	Basalt	9 violations	Yes	6	D
33	Buena Vista	9 violations	Yes	13	F
34	Walsenburg	9 violations	Yes	47	D
35	Monument	8 violations	Yes	23	F
36	Fraser	8 violations	Yes	0	C-
37	Monte Vista	8 violations	Yes	10	D+
38	Meeker	8 violations	Yes	6	C+
39	Strasburg	8 violations	Yes	19	D
40	Haxtun	8 violations	Yes	13	C
41	Walsh	8 violations	Yes	18	D+
42	Littleton	7 violations	Yes	16	F
43	Aspen	7 violations	Yes	2	D
44	Lafayette	7 violations	Yes	19	F
45	Rifle	7 violations	Yes	64	D
46	Hotchkiss	7 violations	Yes	145	F
47	Antonito	7 violations	Yes	17	F
48	Cheyenne Wells	7 violations	Yes	11	B
49	Evergreen	6 violations	Yes	57	F
50	Cedaredge	6 violations	Yes	67	D
51	Telluride	6 violations	Yes	21	D
52	Leadville	6 violations	Yes	3	D
53	Salida	6 violations	Yes	2	D
54	Fairplay	6 violations	Yes	2	C
55	Ft Morgan	6 violations	Yes	61	F
56	Parker	5 violations	Yes	4	F
57	Sterling	5 violations	Yes	29	C-
58	Peyton	5 violations	Yes	2	B-
59	Alamosa	5 violations	Yes	44	D
60	Rocky Ford	5 violations	Yes	325	F
61	Bennett	5 violations	Yes	5	A-
62	Administrative Contact	5 violations	Yes	9	F
63	Paonia	5 violations	Yes	29	D
64	Grand Lake	5 violations	Yes	3	B+
65	Palmer Lake	5 violations	Yes	15	D
66	San Luis	5 violations	Yes	9	D
67	Gainesville	5 violations	Yes	2	A-
68	Manassa	5 violations	Yes	3	B
69	Manzanola	5 violations	Yes	340	D+
70	Stratton	5 violations	Yes	8	C-
71	Otis	5 violations	Yes	2	C+
72	Woody Creek	5 violations	Yes	2	D+
73	Clark	5 violations	Yes	6	C-
74	Centennial	4 violations	Yes	18	F
75	Wheat Ridge	4 violations	Yes	56	D
76	Winter Park	4 violations	Yes	7	D
77	Morrison	4 violations	Yes	12	C+
78	Milliken	4 violations	Yes	0	B
79	Center	4 violations	Yes	0	A-
80	Edwards	4 violations	Yes	43	C
81	Deer Trail	4 violations	Yes	7	A-
82	Ridgway	4 violations	Yes	11	D+
83	Indian Hills	4 violations	Yes	8	B
84	Fowler	4 violations	Yes	25	B
85	Hugo	4 violations	Yes	2	B-
86	Nathrop	4 violations	Yes	14	B+
87	Granada	4 violations	Yes	11	D
88	Westminster	3 violations	Yes	1	D
89	Montrose	3 violations	Yes	7	F
90	Johnstown	3 violations	Yes	6	B
91	Estes Park	3 violations	Yes	49	D
92	Greenwood Village	3 violations	Yes	24	F
93	Eagle	3 violations	Yes	4	C+
94	Elizabeth	3 violations	Yes	5	B
95	Watkins	3 violations	Yes	3	D
96	Hudson	3 violations	Yes	12	D
97	Ignacio	3 violations	Yes	6	F
98	Mancos	3 violations	Yes	3	C
99	Crestone	3 violations	Yes	2	B-
100	Flagler	3 violations	Yes	2	A-
101	Del Norte	3 violations	Yes	4	B
102	Holly	3 violations	Yes	60	D+
103	Pine Bluffs	3 violations	Yes	17	D+
104	Pine Bluffs	3 violations	Yes	17	D+
105	Eads	3 violations	Yes	1	A
106	Saguache	3 violations	Yes	1	D+
107	Loveland	2 violations	Yes	50	F
108	Trinidad	2 violations	Yes	12	D
109	Pagosa Springs	2 violations	Yes	25	F
110	Gunnison	2 violations	Yes	14	C
111	Glendale	2 violations	Yes	3	D
112	Keenesburg	2 violations	Yes	5	A-
113	Hayden	2 violations	Yes	6	D
114	Lyons	2 violations	Yes	61	D
115	Mount Crested Butte	2 violations	Yes	0	A-
116	Cripple Creek	2 violations	Yes	1	B
117	Wiley	2 violations	Yes	376	D+
118	La Veta	2 violations	Yes	26	F
119	Julesburg	2 violations	Yes	4	B-
120	Pierce	2 violations	Yes	1	A
121	Beulah	2 violations	Yes	66	D
122	Debeque	2 violations	Yes	3	C+
123	Nucla	2 violations	Yes	9	D
124	Dove Creek	2 violations	Yes	8	C-
125	Rye	2 violations	Yes	69	D
126	Moffat	2 violations	Yes	1	B-
127	Thornton	1 violations	Yes	3	F
128	Golden	1 violations	Yes	18	B-
129	Vail	1 violations	Yes	0	A
130	Erie	1 violations	Yes	1	A
131	Canon City	1 violations	Yes	4	B+
132	Evans	1 violations	Yes	0	B+
133	Niwot	1 violations	Yes	1	A
134	Wellington	1 violations	Yes	4	B-
135	Black Hawk	1 violations	Yes	0	A-
136	Keystone	1 violations	Yes	1	C
137	Redvale	1 violations	Yes	0	D
138	Craig	1 violations	Yes	0	B
139	Florence	1 violations	Yes	2	C+
140	Georgetown	1 violations	Yes	2	A-
141	Larkspur	1 violations	Yes	11	D+
142	Palisade	1 violations	Yes	2	C-
143	Holyoke	1 violations	Yes	8	C+
144	Rangely	1 violations	Yes	3	C+
145	Las Animas	1 violations	Yes	6	B+
146	Kremmling	1 violations	Yes	3	C
147	Akron	1 violations	Yes	4	B
148	Ordway	1 violations	Yes	4	C+
149	Lasalle	1 violations	Yes	1	C+
150	Creede	1 violations	Yes	0	B
151	Parachute	1 violations	Yes	1	A-
152	Ouray	1 violations	Yes	1	C-
153	Springfield	1 violations	Yes	4	B+
154	Gilcrest	1 violations	Yes	2	B+
155	Log Lane Village	1 violations	Yes	2	B+
156	Bailey	1 violations	Yes	1	C
157	Mulberry	1 violations	Yes	1	B-
158	Des Plaines	1 violations	Yes	0	A
159	Lake City	1 violations	Yes	1	A-
160	Tabernash	1 violations	Yes	0	A
161	Sedalia	1 violations	Yes	9	C+

FAQ

Frequently asked questions about nitrate in Colorado

Is nitrate in Colorado tap water dangerous?

Yes — 161 cities in Colorado 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 Colorado 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.

More contaminants