Manganese Contamination

Manganese in Wisconsin Drinking Water

Ranked by max manganese detected (µg/L) · UCMR 4 data (2018–2020) · Data from EPA SDWIS & UCMR

Cities Tested

Over SMCL

25%

% Over SMCL

46.9 µg/L

State Avg

▲ 7% vs national

vs National

388

Health Violations

Analysis

Manganese in Wisconsin: what the data shows

Wisconsin has 80 cities with manganese data from the EPA's UCMR 4 program (2018–2020). Manganese exceeded the 50 µg/L EPA secondary MCL in 20 of those cities. The state average max detected level is 46.9 µg/L. Manganese occurs naturally in groundwater and surface water. Elevated levels are common in areas with iron-rich geology and in systems that draw from reservoirs with low dissolved oxygen. The secondary MCL of 50 µg/L is based on aesthetic concerns (taste, staining), but health-based guidelines suggest neurological effects at higher concentrations. Emerging research links chronic manganese exposure in drinking water to neurodevelopmental effects in children, including reduced IQ and behavioral issues. Oxidation filtration and water softeners are effective at removing manganese from household water.

Comparison

Cities exceeding 50 µg/L EPA Secondary MCL

Wisconsin

25%

20 of 80 cities

→ ▲ 7% above national rate (worse)

National avg

18%

729 of 4068 cities

City Map

Manganese data across Wisconsin

Each dot is a city with UCMR 4 manganese testing data. Cities where manganese exceeds the 50 µg/L EPA secondary MCL are highlighted. Size reflects population served.

Worst Offenders

Top 10 cities by manganese level in Wisconsin

Highest Manganese levels (µg/L)

All Cities

All Wisconsin cities ranked by manganese level

#	City	Level	Over SMCL?	Violations	Grade
1	La Crosse	482.0 µg/L	Over SMCL	34	F
2	Germantown	406.0 µg/L	Over SMCL	8	B-
3	Weston	266.6 µg/L	Over SMCL	0	B+
4	West Bend	199.7 µg/L	Over SMCL	11	F
5	Sussex	160.5 µg/L	Over SMCL	70	D+
6	Whitewater	154.1 µg/L	Over SMCL	22	C+
7	Omro	153.2 µg/L	Over SMCL	1	A-
8	Cedarburg	137.5 µg/L	Over SMCL	1	B+
9	Fort Atkinson	137.4 µg/L	Over SMCL	14	A-
10	Baraboo	122.8 µg/L	Over SMCL	0	B
11	Beloit	112.0 µg/L	Over SMCL	2	B+
12	New Lisbon	100.1 µg/L	Over SMCL	3	B+
13	Onalaska	96.5 µg/L	Over SMCL	2	A-
14	Stevens Point	87.9 µg/L	Over SMCL	14	C+
15	Saukville	79.1 µg/L	Over SMCL	0	B
16	Amherst	71.4 µg/L	Over SMCL	1	B
17	Waukesha	62.9 µg/L	Over SMCL	320	D
18	Marshfield	57.6 µg/L	Over SMCL	9	C-
19	Hartford	55.8 µg/L	Over SMCL	2	B+
20	Madison	50.2 µg/L	Over SMCL	14	F
21	River Falls	47.2 µg/L	No	14	C+
22	Cottage Grove	44.5 µg/L	No	2	A-
23	Middleton	43.6 µg/L	No	3	C+
24	Waunakee	40.3 µg/L	No	11	B-
25	Brookfield	37.1 µg/L	No	32	C-
26	Wausau	35.7 µg/L	No	24	C
27	Waterloo	35.5 µg/L	No	5	A-
28	Coon Valley	33.4 µg/L	No	2	B+
29	Grafton	30.7 µg/L	No	12	C+
30	Kaukauna	29.3 µg/L	No	9	B+
31	Mount Horeb	28.7 µg/L	No	1	A
32	Menomonie	27.9 µg/L	No	30	F
33	Fitchburg	27.3 µg/L	No	0	A
34	Fall River	26.0 µg/L	No	3	B+
35	Two Rivers	25.8 µg/L	No	5	C-
36	Viroqua	24.5 µg/L	No	2	A-
37	Marinette	24.0 µg/L	No	0	A-
38	North Fond Du Lac	20.9 µg/L	No	6	B
39	Portage	18.0 µg/L	No	9	B
40	Stoughton	16.9 µg/L	No	4	B+
41	Hudson	16.6 µg/L	No	4	B
42	Waterford	16.2 µg/L	No	13	B
43	Platteville	15.9 µg/L	No	11	D+
44	Oconomowoc	15.1 µg/L	No	13	B
45	Caledonia	14.0 µg/L	No	1	B
46	Eau Claire	5.4 µg/L	No	18	D+
47	Appleton	4.7 µg/L	No	4	B+
48	Janesville	4.3 µg/L	No	12	B
49	Little Chute	3.9 µg/L	No	1	B+
50	Superior	3.9 µg/L	No	17	F
51	Monroe	3.7 µg/L	No	9	A-
52	Sun Prairie	3.2 µg/L	No	4	A
53	Shorewood	2.8 µg/L	No	1	A-
54	Racine	2.4 µg/L	No	4	C+
55	Green Bay	2.3 µg/L	No	74	D+
56	Franklin	2.3 µg/L	No	10	B
57	Whitefish Bay	2.2 µg/L	No	0	B+
58	Menasha	2.1 µg/L	No	1	B+
59	Pleasant Prairie	2.0 µg/L	No	7	B+
60	Glendale	2.0 µg/L	No	1	A-
61	Wisconsin Rapids	2.0 µg/L	No	6	B-
62	Watertown	1.6 µg/L	No	10	D
63	Oshkosh	1.3 µg/L	No	0	A
64	Grand Chute	1.2 µg/L	No	2	A
65	Brown Deer	1.2 µg/L	No	5	A
66	West Allis	1.2 µg/L	No	0	A-
67	Fond Du Lac	1.2 µg/L	No	51	F
68	Chippewa Falls	1.1 µg/L	No	12	D+
69	Menomonee Falls	0.8 µg/L	No	6	B+
70	Manitowoc	0.7 µg/L	No	0	B+
71	Cornell	0.7 µg/L	No	6	A
72	Sheboygan	0.7 µg/L	No	1	A-
73	Greendale	0.7 µg/L	No	1	A-
74	Kenosha	0.7 µg/L	No	11	D
75	Sheboygan Falls	0.6 µg/L	No	5	B-
76	South Milwaukee	0.6 µg/L	No	0	A-
77	New Berlin	0.6 µg/L	No	14	B
78	Milwaukee	0.5 µg/L	No	2	A
79	Wauwatosa	0.5 µg/L	No	1	B+
80	Beaver Dam	0.4 µg/L	No	11	A-

FAQ

Frequently asked questions about manganese in Wisconsin

Is manganese in Wisconsin tap water harmful?

The EPA secondary MCL for manganese is 50 µg/L, set primarily for aesthetic reasons (taste, color, staining). 20 cities in Wisconsin exceed the secondary MCL. However, emerging research links chronic manganese exposure above 50–100 µg/L to neurodevelopmental effects in children, including reduced IQ.

How can I remove manganese from my drinking water?

Oxidation filtration (such as greensand or birm filters) is the most common and effective method for removing manganese from well water. Water softeners using ion exchange also work well. Standard carbon filters provide limited manganese removal. If your water has a metallic taste or brown/black discoloration, manganese may be the cause.

What causes high manganese in Wisconsin water?

Manganese occurs naturally in groundwater and surface water, particularly in areas with iron-rich geology. Low dissolved oxygen conditions (common in deep wells and reservoir bottom waters) increase manganese solubility. Industrial sources include mining, steel production, and battery manufacturing. Seasonal changes in reservoir water chemistry can cause manganese spikes.

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