Nitrate Contamination

Nitrate in Washington Drinking Water

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

243

Cities Tested

243

Has Violations

100%

% Has Violations

17.4 violations

State Avg

▼ 0% vs national

vs National

261

Health Violations

Analysis

Nitrate in Washington: what the data shows

Washington has 243 cities with nitrate-related violations. The EPA MCL for nitrate is 10 mg/L (measured as nitrogen). The state has 243 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

Washington

100%

243 of 243 cities

← = Exactly at national rate

National avg

100%

8001 of 8001 cities

City Map

Nitrate data across Washington

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 Washington

Highest Nitrate levels (violations)

All Cities

All Washington cities ranked by nitrate level

#	City	Level	Violations?	Violations	Grade
1	Port Orchard	362 violations	Yes	753	F
2	Coupeville	196 violations	Yes	448	F
3	Yakima	187 violations	Yes	162	F
4	Moses Lake	158 violations	Yes	132	F
5	Lynden	156 violations	Yes	235	F
6	Pasco	114 violations	Yes	137	D
7	Ferndale	108 violations	Yes	110	F
8	Shelton	91 violations	Yes	158	F
9	West Richland	90 violations	Yes	99	F
10	Seattle	83 violations	Yes	138	F
11	Mount Vernon	75 violations	Yes	191	F
12	Nespelem	69 violations	Yes	40	D+
13	Tacoma	64 violations	Yes	232	F
14	Olympia	60 violations	Yes	66	F
15	Arlington	60 violations	Yes	83	F
16	Othello	56 violations	Yes	102	D
17	Tonasket	56 violations	Yes	134	D
18	Kennewick	55 violations	Yes	78	F
19	Poulsbo	54 violations	Yes	95	F
20	Wellpinit	53 violations	Yes	103	D+
21	Bridgeport	49 violations	Yes	47	C
22	Napavine	47 violations	Yes	104	D
23	Vancouver	45 violations	Yes	36	F
24	Lacey	44 violations	Yes	125	F
25	Prosser	44 violations	Yes	42	C+
26	Freeland	43 violations	Yes	129	D
27	Toppenish	43 violations	Yes	12	F
28	Spokane	38 violations	Yes	56	F
29	Deming	37 violations	Yes	23	D
30	Sequim	36 violations	Yes	64	F
31	Quincy	36 violations	Yes	52	D+
32	Burbank	36 violations	Yes	47	D
33	Bellingham	33 violations	Yes	54	F
34	Stanwood	33 violations	Yes	31	D
35	Marysville	32 violations	Yes	12	D
36	Gig Harbor	32 violations	Yes	62	F
37	Cle Elum	32 violations	Yes	105	D
38	Forks	32 violations	Yes	8	D
39	Woodland	30 violations	Yes	16	F
40	Colville	28 violations	Yes	44	D
41	Loon Lake	27 violations	Yes	14	F
42	Wapato	27 violations	Yes	11	F
43	Mattawa	25 violations	Yes	33	C
44	Waverly	23 violations	Yes	25	D
45	Silverdale	22 violations	Yes	17	F
46	Ellensburg	22 violations	Yes	19	D
47	Raymond	22 violations	Yes	76	F
48	Marshall	22 violations	Yes	22	D
49	Oak Harbor	21 violations	Yes	105	F
50	Friday Harbor	21 violations	Yes	153	F
51	Greenacres	18 violations	Yes	12	B+
52	College Place	18 violations	Yes	23	D
53	Union	18 violations	Yes	52	D
54	Republic	18 violations	Yes	181	D
55	Oakville	18 violations	Yes	4	F
56	Cashmere	17 violations	Yes	21	F
57	Auburn	16 violations	Yes	18	D+
58	Walla Walla	16 violations	Yes	84	D
59	Port Angeles	16 violations	Yes	19	F
60	Hoodsport	16 violations	Yes	5	C+
61	Custer	16 violations	Yes	12	C+
62	Snohomish	15 violations	Yes	11	D
63	Monroe	14 violations	Yes	4	C
64	Connell	14 violations	Yes	22	C+
65	Maple Falls	14 violations	Yes	35	D+
66	Puyallup	13 violations	Yes	124	F
67	Kirkland	13 violations	Yes	4	D+
68	Leavenworth	13 violations	Yes	20	C
69	Newport	13 violations	Yes	14	D+
70	Eastsound	13 violations	Yes	29	F
71	Mesa	13 violations	Yes	15	C+
72	Tahola	13 violations	Yes	15	D
73	Dallesport	13 violations	Yes	2	C+
74	Greenbank	13 violations	Yes	9	B-
75	Wenatchee	12 violations	Yes	41	D
76	Yelm	12 violations	Yes	12	D+
77	Montesano	12 violations	Yes	17	F
78	Tekoa	12 violations	Yes	5	C
79	Waterville	12 violations	Yes	10	B
80	Bothell	11 violations	Yes	7	F
81	Port Townsend	11 violations	Yes	15	F
82	Ephrata	11 violations	Yes	13	D
83	Joint Base Lewis-Mcchord	10 violations	Yes	3	B+
84	Issaquah	10 violations	Yes	10	C-
85	Belfair	10 violations	Yes	36	C-
86	Warden	10 violations	Yes	9	D+
87	Onalaska	10 violations	Yes	2	C+
88	Lopez Island	10 violations	Yes	28	F
89	Sammamish	9 violations	Yes	6	C-
90	Buckley	9 violations	Yes	5	D+
91	Spokane Valley	9 violations	Yes	10	C-
92	Cheney	9 violations	Yes	5	A-
93	Chehalis	9 violations	Yes	12	F
94	Vashon	9 violations	Yes	24	F
95	Kalama	9 violations	Yes	0	C+
96	Westport	9 violations	Yes	4	D+
97	Omak	9 violations	Yes	5	D
98	Stevenson	9 violations	Yes	1	C+
99	Black Diamond	9 violations	Yes	13	C-
100	Mossyrock	9 violations	Yes	14	C-
101	Darrington	9 violations	Yes	4	D
102	Lake Tapps	9 violations	Yes	6	B-
103	Maple Valley	8 violations	Yes	7	C+
104	Hoquiam	8 violations	Yes	6	B-
105	Aberdeen	8 violations	Yes	10	D
106	Grandview	8 violations	Yes	5	D+
107	Goldendale	8 violations	Yes	15	B-
108	Washtucna	8 violations	Yes	6	C+
109	Ravensdale	8 violations	Yes	22	B-
110	Kent	7 violations	Yes	31	F
111	Renton	7 violations	Yes	11	D+
112	Port Ludlow	7 violations	Yes	27	C+
113	Zillah	7 violations	Yes	11	D+
114	Quinault	7 violations	Yes	3	D
115	Twisp	7 violations	Yes	6	A
116	Bremerton	6 violations	Yes	13	C
117	Spanaway	6 violations	Yes	9	C+
118	Mead	6 violations	Yes	3	B-
119	Selah	6 violations	Yes	4	B
120	Ocean Park	6 violations	Yes	6	B+
121	Elma	6 violations	Yes	5	B-
122	Medical Lake	6 violations	Yes	9	B-
123	Benton City	6 violations	Yes	17	F
124	Deer Park	6 violations	Yes	2	D
125	White Salmon	6 violations	Yes	9	C+
126	Sumas	6 violations	Yes	17	A-
127	Mabton	6 violations	Yes	1	A-
128	Rosalia	6 violations	Yes	7	A-
129	George	6 violations	Yes	3	A-
130	Pe Ell	6 violations	Yes	16	B-
131	Vashion Island	6 violations	Yes	2	B+
132	Suquamish	6 violations	Yes	4	B+
133	Lake Stevens	6 violations	Yes	7	C
134	Everett	5 violations	Yes	16	D
135	Richland	5 violations	Yes	7	C+
136	Tumwater	5 violations	Yes	24	D+
137	Carlsborg	5 violations	Yes	2	B-
138	Carson	5 violations	Yes	0	C-
139	Winlock	5 violations	Yes	4	B+
140	Fall City	5 violations	Yes	18	B-
141	Ritzville	5 violations	Yes	6	A-
142	Neah Bay	5 violations	Yes	22	D
143	Skokomish Nation	5 violations	Yes	2	B-
144	Ronald	5 violations	Yes	5	C+
145	Woodinville	4 violations	Yes	1	A-
146	Kelso	4 violations	Yes	15	F
147	East Wenatchee	4 violations	Yes	19	B
148	North Bend	4 violations	Yes	7	B+
149	Orting	4 violations	Yes	1	B+
150	Blaine	4 violations	Yes	8	A
151	Brewster	4 violations	Yes	7	D
152	Everson	4 violations	Yes	8	B+
153	Okanogan	4 violations	Yes	11	B+
154	Cathlamet	4 violations	Yes	66	C
155	Royal City	4 violations	Yes	1	A-
156	Lapush	4 violations	Yes	2	B+
157	Lummi Island	4 violations	Yes	32	D+
158	Redmond	3 violations	Yes	4	B-
159	Sumner	3 violations	Yes	0	A-
160	Chelan	3 violations	Yes	18	D
161	Long Beach	3 violations	Yes	15	B
162	Colfax	3 violations	Yes	4	B
163	Rock Island	3 violations	Yes	5	A-
164	South Bend	3 violations	Yes	83	D+
165	Clinton	3 violations	Yes	8	C
166	Allyn	3 violations	Yes	4	A-
167	Snoqualmie	3 violations	Yes	10	A-
168	Graham	3 violations	Yes	5	A
169	Bingen	3 violations	Yes	0	A-
170	Camano Island	3 violations	Yes	9	C
171	Rockford	3 violations	Yes	0	B
172	Sprague	3 violations	Yes	2	B+
173	Pullman	2 violations	Yes	0	B+
174	Camas	2 violations	Yes	2	C
175	Battle Ground	2 violations	Yes	12	B-
176	Enumclaw	2 violations	Yes	1	B+
177	Fircrest	2 violations	Yes	4	A-
178	Snoqualmie Pass	2 violations	Yes	4	B+
179	Moxee	2 violations	Yes	2	B
180	Lake Forest Park	2 violations	Yes	15	D+
181	Tenino	2 violations	Yes	2	B+
182	Bow	2 violations	Yes	7	A-
183	Adna	2 violations	Yes	9	A
184	Joyce	2 violations	Yes	10	A-
185	Kittitas	2 violations	Yes	1	A
186	Morton	2 violations	Yes	3	B-
187	Rochester	2 violations	Yes	5	A-
188	Davenport	2 violations	Yes	14	A-
189	Sedro Woolley	2 violations	Yes	1	A
190	Entiat	2 violations	Yes	0	A-
191	Port Gamble	2 violations	Yes	9	A-
192	Winthrop	2 violations	Yes	57	B
193	Pomeroy	2 violations	Yes	1	B+
194	Roy	2 violations	Yes	0	B+
195	Pateros	2 violations	Yes	2	B+
196	Wilkeson	2 violations	Yes	0	A
197	North Bonneville	2 violations	Yes	0	A-
198	Spangle	2 violations	Yes	3	B+
199	Albion	2 violations	Yes	7	A
200	Edmonds	1 violations	Yes	0	A-
201	Longview	1 violations	Yes	0	B+
202	Fife	1 violations	Yes	4	A
203	Centralia	1 violations	Yes	5	B-
204	Clarkston	1 violations	Yes	16	B+
205	Washougal	1 violations	Yes	2	B+
206	Ridgefield	1 violations	Yes	0	D
207	Liberty Lake	1 violations	Yes	2	A
208	Manchester	1 violations	Yes	7	A
209	Airway	1 violations	Yes	2	B
210	Sultan	1 violations	Yes	33	B
211	Union Gap	1 violations	Yes	5	A
212	Fairchild Afb	1 violations	Yes	0	B+
213	Granger	1 violations	Yes	3	A
214	Eatonville	1 violations	Yes	2	A-
215	Dayton	1 violations	Yes	4	A-
216	Oroville	1 violations	Yes	7	A-
217	Malaga	1 violations	Yes	6	A
218	Chewelah	1 violations	Yes	7	B+
219	Mccleary	1 violations	Yes	0	A
220	Rainier	1 violations	Yes	1	A-
221	Ilwaco	1 violations	Yes	4	A
222	Nooksack	1 violations	Yes	5	A
223	Glacier	1 violations	Yes	3	A-
224	Falls City	1 violations	Yes	2	B+
225	Toledo	1 violations	Yes	2	A-
226	Waitsburg	1 violations	Yes	1	A
227	Newman Lake	1 violations	Yes	6	A+
228	Langley	1 violations	Yes	2	D
229	Ashford	1 violations	Yes	3	A-
230	Packwood	1 violations	Yes	2	A-
231	Pouslbo	1 violations	Yes	4	A
232	Lind	1 violations	Yes	7	B+
233	Carbonado	1 violations	Yes	41	B
234	Cusick	1 violations	Yes	7	B+
235	Acme	1 violations	Yes	4	A-
236	Chinook	1 violations	Yes	23	A-
237	Startup	1 violations	Yes	4	A
238	Littlerock	1 violations	Yes	3	A
239	Malott	1 violations	Yes	3	A-
240	Randle	1 violations	Yes	0	A
241	Mckenna	1 violations	Yes	0	A-
242	Bucoda	1 violations	Yes	5	B+
243	South Cle Elum	1 violations	Yes	0	A-

FAQ

Frequently asked questions about nitrate in Washington

Is nitrate in Washington tap water dangerous?

Yes — 243 cities in Washington 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 Washington 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