Manganese Contamination

Manganese in Oklahoma Drinking Water

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

Cities Tested

Over SMCL

13%

% Over SMCL

17.2 µg/L

State Avg

▼ 5% vs national

vs National

351

Health Violations

Analysis

Manganese in Oklahoma: what the data shows

Oklahoma has 48 cities with manganese data from the EPA's UCMR 4 program (2018–2020). Manganese exceeded the 50 µg/L EPA secondary MCL in 6 of those cities. The state average max detected level is 17.2 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

Oklahoma

13%

6 of 48 cities

← ▼ 5% below national rate (better)

National avg

18%

729 of 4068 cities

City Map

Manganese data across Oklahoma

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 Oklahoma

Highest Manganese levels (µg/L)

All Cities

All Oklahoma cities ranked by manganese level

#	City	Level	Over SMCL?	Violations	Grade
1	Atoka	190.0 µg/L	Over SMCL	269	D+
2	Oklahoma City	94.8 µg/L	Over SMCL	56	F
3	Calumet	90.6 µg/L	Over SMCL	117	D
4	Fort Sill	56.0 µg/L	Over SMCL	4	A
5	Madill	54.0 µg/L	Over SMCL	178	F
6	Ardmore	53.5 µg/L	Over SMCL	188	F
7	Moore	39.8 µg/L	No	53	F
8	Harrah	24.0 µg/L	No	61	D
9	Miami	20.9 µg/L	No	11	D
10	Chickasha	19.5 µg/L	No	79	F
11	Claremore	14.2 µg/L	No	153	F
12	Stillwater	13.0 µg/L	No	72	F
13	Lawton	11.5 µg/L	No	23	F
14	Skiatook	11.0 µg/L	No	72	B-
15	Tahlequah	10.9 µg/L	No	56	F
16	Okmulgee	10.8 µg/L	No	262	D
17	Bartlesville	9.5 µg/L	No	217	F
18	Norman	8.5 µg/L	No	52	F
19	Broken Arrow	7.9 µg/L	No	113	F
20	Durant	7.4 µg/L	No	104	D
21	Grove	7.3 µg/L	No	20	D
22	Crowder	6.4 µg/L	No	91	C+
23	Elk City	6.1 µg/L	No	5	D
24	Edmond	6.1 µg/L	No	86	F
25	Wewoka	4.6 µg/L	No	340	D+
26	Bixby	4.5 µg/L	No	1	B
27	Duncan	4.4 µg/L	No	150	D+
28	Sand Springs	3.7 µg/L	No	20	B
29	Mcalester	3.4 µg/L	No	670	F
30	Guymon	3.0 µg/L	No	10	A-
31	Spiro	2.9 µg/L	No	166	D+
32	El Reno	2.8 µg/L	No	49	D
33	Bethany	2.6 µg/L	No	14	B+
34	Midwest City	2.5 µg/L	No	11	B+
35	Jenks	2.0 µg/L	No	31	B-
36	Sallisaw	1.9 µg/L	No	29	D+
37	Woodward	1.8 µg/L	No	55	D
38	Sapulpa	1.6 µg/L	No	85	D
39	Enid	1.3 µg/L	No	33	F
40	Idabel	1.2 µg/L	No	123	D
41	Del City	1.1 µg/L	No	12	F
42	Shawnee	1.0 µg/L	No	124	D
43	Stuart	0.7 µg/L	No	96	C-
44	Allen	0.7 µg/L	No	5	A-
45	Council Hill	0.6 µg/L	No	177	D+
46	Muskogee	0.6 µg/L	No	246	D
47	Owasso	0.5 µg/L	No	8	C+
48	Tulsa	0.4 µg/L	No	6	D

FAQ

Frequently asked questions about manganese in Oklahoma

Is manganese in Oklahoma tap water harmful?

The EPA secondary MCL for manganese is 50 µg/L, set primarily for aesthetic reasons (taste, color, staining). 6 cities in Oklahoma 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 Oklahoma 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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