Arsenic Contamination

Arsenic in Wisconsin Drinking Water

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

Cities Tested

Has Violations

100%

% Has Violations

3.0 violations

State Avg

▼ 0% vs national

vs National

388

Health Violations

Analysis

Arsenic in Wisconsin: what the data shows

Wisconsin has 70 cities with arsenic-related violations on record. Arsenic contamination is a federal MCL violation at levels above 10 µg/L (10 ppb). The state has 70 cities with at least one arsenic violation. Arsenic enters drinking water primarily through erosion of natural deposits, particularly in western states with arsenite-bearing geology. Industrial sources include mining runoff, glass manufacturing, and semiconductor production. Groundwater systems are significantly more likely to have arsenic issues than surface water systems. Long-term arsenic exposure above the MCL increases the risk of bladder, lung, and skin cancer, as well as cardiovascular disease and diabetes. Reverse osmosis and specialized arsenic-removal media are the most effective point-of-use treatment options.

Comparison

Cities exceeding 10 µg/L EPA MCL

Wisconsin

100%

70 of 70 cities

← = Exactly at national rate

National avg

100%

5489 of 5489 cities

City Map

Arsenic data across Wisconsin

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

Worst Offenders

Top 10 cities by arsenic level in Wisconsin

Highest Arsenic levels (violations)

All Cities

All Wisconsin cities ranked by arsenic level

#	City	Level	Violations?	Violations	Grade
1	Thiensville	20 violations	Yes	30	D
2	Lodi	16 violations	Yes	20	B-
3	Clintonville	14 violations	Yes	15	B
4	West Bend	7 violations	Yes	11	F
5	Grafton	7 violations	Yes	12	C+
6	Twin Lakes	7 violations	Yes	29	F
7	Keshena	6 violations	Yes	6	C+
8	Crandon	6 violations	Yes	8	D+
9	Wales	6 violations	Yes	7	C+
10	Oconomowoc	5 violations	Yes	13	B
11	Lake Geneva	5 violations	Yes	24	C
12	Muskego	5 violations	Yes	36	D
13	Hayward	5 violations	Yes	19	F
14	Suring	5 violations	Yes	5	B-
15	Whitewater	4 violations	Yes	22	C+
16	Algoma	4 violations	Yes	2	A-
17	Dousman	4 violations	Yes	12	C
18	Kenosha	3 violations	Yes	11	D
19	Fond Du Lac	3 violations	Yes	51	F
20	Pewaukee	3 violations	Yes	71	F
21	River Falls	3 violations	Yes	14	C+
22	Ladysmith	3 violations	Yes	18	D
23	Bayfield	3 violations	Yes	7	C
24	Odanah	3 violations	Yes	2	D+
25	La Crosse	2 violations	Yes	34	F
26	Menomonie	2 violations	Yes	30	F
27	Mequon	2 violations	Yes	21	F
28	Waunakee	2 violations	Yes	11	B-
29	Burlington	2 violations	Yes	27	B-
30	Elkhorn	2 violations	Yes	19	F
31	Holmen	2 violations	Yes	5	B-
32	Delavan	2 violations	Yes	6	F
33	Mauston	2 violations	Yes	17	F
34	Walworth	2 violations	Yes	8	B-
35	Wautoma	2 violations	Yes	0	A
36	Webster	2 violations	Yes	13	B+
37	Chetek	2 violations	Yes	6	C+
38	Elm Grove	2 violations	Yes	28	F
39	Turtle Lake	2 violations	Yes	2	A+
40	Iron River	2 violations	Yes	11	C+
41	Green Bay	1 violations	Yes	74	D+
42	Eau Claire	1 violations	Yes	18	D+
43	Brookfield	1 violations	Yes	32	C-
44	Oak Creek	1 violations	Yes	5	B
45	Stevens Point	1 violations	Yes	14	C+
46	New Berlin	1 violations	Yes	14	B
47	Chippewa Falls	1 violations	Yes	12	D+
48	Plover	1 violations	Yes	9	B+
49	Platteville	1 violations	Yes	11	D+
50	Black River Falls	1 violations	Yes	11	D+
51	Two Rivers	1 violations	Yes	5	C-
52	Union Grove	1 violations	Yes	26	D
53	Edgerton	1 violations	Yes	17	D
54	Evansville	1 violations	Yes	25	C-
55	West Salem	1 violations	Yes	3	B+
56	Oneida	1 violations	Yes	3	D
57	Mosinee	1 violations	Yes	15	F
58	Medford	1 violations	Yes	9	C+
59	Fox Lake	1 violations	Yes	6	B
60	Osceola	1 violations	Yes	8	B
61	Delafield	1 violations	Yes	22	D
62	Bristol	1 violations	Yes	10	B
63	Campbellsport	1 violations	Yes	5	C+
64	Fontana	1 violations	Yes	8	B-
65	Randolph	1 violations	Yes	7	B
66	Galesville	1 violations	Yes	3	C
67	Bonduel	1 violations	Yes	0	A-
68	Augusta	1 violations	Yes	2	D+
69	Eleva	1 violations	Yes	5	D
70	South Wayne	1 violations	Yes	13	A-

FAQ

Frequently asked questions about arsenic in Wisconsin

Is arsenic in Wisconsin tap water a concern?

Yes — 70 cities in Wisconsin have arsenic-related violations on record. The EPA MCL for arsenic is 10 µg/L. Even at levels below the MCL, long-term arsenic exposure has been linked to cancer and cardiovascular disease.

How can I remove arsenic from my drinking water in Wisconsin?

Reverse osmosis (RO) systems are the most effective at removing arsenic, typically reducing it by 90% or more. Specialized arsenic-removal media (such as iron-based adsorption filters) are also highly effective. Standard carbon filters and pitcher filters do NOT effectively remove arsenic. If your water comes from a private well, have it tested for arsenic.

Where does arsenic in Wisconsin water come from?

Arsenic enters drinking water primarily through natural erosion of arsenic-bearing rock formations. It is most common in groundwater systems in the western United States, parts of the Midwest, and New England. Industrial sources include mining, smelting, and agricultural pesticide residues. Groundwater sources are far more likely to contain arsenic than surface water.

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