Manganese Contamination

Manganese in Louisiana Drinking Water

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

Cities Tested

Over SMCL

31%

% Over SMCL

70.9 µg/L

State Avg

▲ 13% vs national

vs National

303

Health Violations

Analysis

Manganese in Louisiana: what the data shows

Louisiana has 59 cities with manganese data from the EPA's UCMR 4 program (2018–2020). Manganese exceeded the 50 µg/L EPA secondary MCL in 18 of those cities. The state average max detected level is 70.9 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

Louisiana

31%

18 of 59 cities

→ ▲ 13% above national rate (worse)

National avg

18%

729 of 4068 cities

City Map

Manganese data across Louisiana

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 Louisiana

Highest Manganese levels (µg/L)

All Cities

All Louisiana cities ranked by manganese level

#	City	Level	Over SMCL?	Violations	Grade
1	Bastrop	1170.0 µg/L	Over SMCL	46	F
2	Plaquemine	386.0 µg/L	Over SMCL	26	C-
3	Logansport	280.0 µg/L	Over SMCL	28	C-
4	Arnaudville	220.0 µg/L	Over SMCL	44	C
5	Denham Springs	210.0 µg/L	Over SMCL	6	B
6	Bogalusa	178.0 µg/L	Over SMCL	24	D
7	Benton	136.5 µg/L	Over SMCL	43	F
8	Gonzales	122.0 µg/L	Over SMCL	16	A-
9	Hammond	110.0 µg/L	Over SMCL	96	F
10	Baton Rouge	106.0 µg/L	Over SMCL	30	F
11	Walker	96.7 µg/L	Over SMCL	7	A-
12	Sulphur	93.8 µg/L	Over SMCL	24	B+
13	Cecilia	86.9 µg/L	Over SMCL	11	B-
14	Lafayette	75.7 µg/L	Over SMCL	42	F
15	Lawtell	75.6 µg/L	Over SMCL	11	A-
16	Baker	72.9 µg/L	Over SMCL	2	A-
17	Monroe	67.4 µg/L	Over SMCL	64	F
18	Opelousas	64.6 µg/L	Over SMCL	28	C-
19	Mandeville	46.0 µg/L	No	170	F
20	Parks	42.9 µg/L	No	15	C
21	Minden	42.8 µg/L	No	40	F
22	Alexandria	41.1 µg/L	No	113	F
23	Blanchard	39.9 µg/L	No	26	B+
24	Stonewall	38.0 µg/L	No	1	A-
25	Lake Charles	33.3 µg/L	No	63	F
26	Covington	33.3 µg/L	No	93	F
27	Tioga	31.8 µg/L	No	7	A-
28	Longville	25.7 µg/L	No	5	A-
29	Lockport	24.8 µg/L	No	4	A+
30	Zachary	23.3 µg/L	No	8	B-
31	Natchitoches	21.8 µg/L	No	20	A
32	Deville	20.3 µg/L	No	1	A
33	Sunset	20.0 µg/L	No	21	C+
34	Ruston	15.6 µg/L	No	20	B
35	Shreveport	15.3 µg/L	No	69	F
36	Slidell	14.8 µg/L	No	73	F
37	Pineville	14.3 µg/L	No	15	F
38	St. Francisville	12.0 µg/L	No	9	B+
39	Oakdale	8.1 µg/L	No	29	D
40	Barksdale Afb	6.1 µg/L	No	16	A
41	Fordoche	5.7 µg/L	No	2	B-
42	Gretna	5.5 µg/L	No	19	A-
43	Clarks	5.4 µg/L	No	6	C
44	Jennings	4.3 µg/L	No	10	B+
45	Thibodaux	4.2 µg/L	No	27	A-
46	Bossier City	4.1 µg/L	No	109	F
47	Deridder	4.0 µg/L	No	4	B+
48	Houma	3.8 µg/L	No	6	B+
49	Morgan City	3.6 µg/L	No	20	B
50	Abbeville	3.5 µg/L	No	10	B+
51	West Monroe	3.1 µg/L	No	443	D+
52	Jefferson	3.0 µg/L	No	2	A-
53	Maurice	2.5 µg/L	No	15	C+
54	Duson	1.8 µg/L	No	12	C-
55	New Orleans	1.6 µg/L	No	27	F
56	Ferriday	1.6 µg/L	No	259	F
57	Laplace	1.1 µg/L	No	89	D+
58	Belle Chasse	0.6 µg/L	No	112	F
59	Welsh	0.5 µg/L	No	5	A-

FAQ

Frequently asked questions about manganese in Louisiana

Is manganese in Louisiana tap water harmful?

The EPA secondary MCL for manganese is 50 µg/L, set primarily for aesthetic reasons (taste, color, staining). 18 cities in Louisiana 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 Louisiana 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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