Nitrate in Minnesota well water, by county

Name: Nitrate in private wells by county, Minnesota
Creator: Tested Water
License: https://creativecommons.org/licenses/by/4.0/

By the Tested Water teamLab data from the USGS and EPA Water Quality Portal, 2000 to 2025Updated November 8, 2026

Nitrate is widespread, over the limit in 15% or more of tested wells, in 9 of the 54 Minnesota counties with 10 or more tested wells. A county's share tells you how likely a problem is nearby. Only a test of your own well tells you what's in it.

Find a nitrate test See every county

How Minnesota compares with the rest of the country

Across Minnesota, about 1 in 14 tested wells had nitrate over the EPA limit of 10 mg/L (375 of 5,138). Across all tested wells in the US it's about 1 in 12. Minnesota is about average, so the county you live in tells you more than the state does.

Why it matters: It's dangerous for babies under 6 months, because it keeps their blood from carrying enough oxygen.

Nitrate soaks down into groundwater from fertilizer, manure and septic systems.

Nitrate in tested wells, county by county

Share of each county's tested wells with at least one result over the EPA limit of 10 mg/L. Counties need 10 or more tested wells to be listed. Widespread means 15% or more, worth checking 5 to 15%, rare under 5%.

County	Wells tested	Wells over the limit	Level
Stearns County	56	61% 34 of 56	Widespread
Rock County	62	35% 22 of 62	Widespread
Pope County	93	26% 24 of 93	Widespread
Polk County	46	22% 10 of 46	Widespread
Dakota County	154	21% 32 of 154	Widespread
Otter Tail County	239	20% 48 of 239	Widespread
Wadena County	113	18% 20 of 113	Widespread
Benton County	100	16% 16 of 100	Widespread
Cottonwood County	20	15% 3 of 20	Widespread
Sherburne County	129	15% 19 of 129	Worth checking
Kandiyohi County	99	11% 11 of 99	Worth checking
Hubbard County	112	11% 12 of 112	Worth checking
Winona County	88	10% 9 of 88	Worth checking
Morrison County	113	10% 11 of 113	Worth checking
Nobles County	68	9% 6 of 68	Worth checking
Watonwan County	12	8% 1 of 12	Worth checking
Nicollet County	101	8% 8 of 101	Worth checking
Kanabec County	91	8% 7 of 91	Worth checking
Beltrami County	15	7% 1 of 15	Worth checking
Becker County	98	6% 6 of 98	Worth checking
Washington County	205	6% 12 of 205	Worth checking
Goodhue County	86	5% 4 of 86	Rare
Olmsted County	118	4% 5 of 118	Rare
Hennepin County	155	4% 6 of 155	Rare
Todd County	78	4% 3 of 78	Rare
Anoka County	196	3% 6 of 196	Rare
Douglas County	35	3% 1 of 35	Rare
Wabasha County	76	3% 2 of 76	Rare
Brown County	92	2% 2 of 92	Rare
Dodge County	93	2% 2 of 93	Rare
Isanti County	94	2% 2 of 94	Rare
Renville County	98	2% 2 of 98	Rare
Redwood County	111	2% 2 of 111	Rare
Chisago County	83	1% 1 of 83	Rare
Lac qui Parle County	90	1% 1 of 90	Rare
Sibley County	91	1% 1 of 91	Rare
Clay County	93	1% 1 of 93	Rare
Cass County	99	1% 1 of 99	Rare
Crow Wing County	110	1% 1 of 110	Rare
St. Louis County	194	0% 0 of 194	Rare
Carlton County	109	0% 0 of 109	Rare
Blue Earth County	100	0% 0 of 100	Rare
Meeker County	95	0% 0 of 95	Rare
Wright County	93	0% 0 of 93	Rare
Aitkin County	91	0% 0 of 91	Rare
Lake County	91	0% 0 of 91	Rare
Steele County	90	0% 0 of 90	Rare
Houston County	86	0% 0 of 86	Rare
McLeod County	75	0% 0 of 75	Rare
Pine County	75	0% 0 of 75	Rare
Carver County	66	0% 0 of 66	Rare
Scott County	20	0% 0 of 20	Rare
Itasca County	13	0% 0 of 13	Rare
Stevens County	13	0% 0 of 13	Rare

27 more Minnesota counties have 1 to 9 tested wells for nitrate, too few to rate.

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Where to get your well tested for nitrate in Minnesota

Your county health department

Minnesota doesn't run a statewide free testing program that we know of. Some county health departments test wells or sell kits, so call yours first.

Minnesota's private well page

A lab Minnesota certifies

Ask for nitrate by name. Results from a certified lab count for a home sale or a loan.

Labs certified by Minnesota

A mail-in kit

Fill the bottles at your kitchen tap and mail them back. We mark the kits that include nitrate.

Compare kits

Keep reading about wells in Minnesota

Well water testing in Minnesota: how to get tested and what turns up statewide
Nitrate in well water: where it comes from, what it does and how to remove it
Arsenic in Minnesota wells, by county
Manganese in Minnesota wells, by county
Lead in Minnesota wells, by county

Questions people ask about nitrate in Minnesota

Is there nitrate in Minnesota well water?

Nitrate is widespread, over the limit in 15% or more of tested wells, in 9 of the 54 Minnesota counties with 10 or more tested wells. Across Minnesota, about 1 in 14 tested wells had nitrate over the EPA limit of 10 mg/L (375 of 5,138). Across all tested wells in the US it's about 1 in 12. Minnesota is about average, so the county you live in tells you more than the state does.

Where can I get my well tested for nitrate in Minnesota?

Use a lab certified by Minnesota for drinking water, or a mail-in kit that includes nitrate from a certified lab. Some county health departments test wells too, so call yours first.

See Minnesota's list of certified labs, or compare mail-in kits.

Where these numbers come from

Lab tests: Water Quality Portal (USGS and EPA), well samples since 2000. A well counts as over if any of its tests was over the EPA limit of 10 mg/L. Wells tested for studies and monitoring, not a random sample of homes.
Likely overstated: our own check of who tested the wells, when and where. How we check.
State programs and links: Minnesota Department of Health.