privatewelldata / States / Minnesota / Nitrate
Nitrate in well water in Minnesota
6% of 7,259 sampled wells in Minnesota had nitrate above the EPA limit of 10 mg/L (as nitrogen) (latest result per well, 87 counties, samples 1932–2018). The highest county share was Isanti County: 30% of 50 wells. Data updated 2026-10-18.
of sampled wells above 10 mg/L (as nitrogen)
wells with a result
counties with data
counties where 1 in 4+ wells were above
Nitrate in wells most often comes from fertilizer, manure and septic systems, so shallow wells near fields or septic fields are more exposed, and levels can change with the seasons. Only a lab test shows it. Federal limits apply to public water systems; a private well is the owner's responsibility to test (EPA).
% of sampled wells above the EPA limit (latest result per well; counties with 10+ wells). Source: USGS/EPA Water Quality Portal, 2026-10-18 · privatewelldata.com
Nitrate by county in Minnesota
| County | Above 10 mg/L (as nitrogen) | Median | 90th pct. | Years |
|---|---|---|---|---|
| Isanti County | 30% of 50 | 1.15 mg/L as N | 35.014 | 1968–2010 |
| Pipestone County | 22% of 18 | 2.566 mg/L as N | 17 | 1962–2007 |
| Stearns County | 20% of 327 | 1 mg/L as N | 20 | 1964–2007 |
| Rock County | 17% of 41 | 0.63 mg/L as N | 14 | 1958–1997 |
| Sherburne County | 15% of 228 | 0.119 mg/L as N | 15 | 1963–2018 |
| Kandiyohi County | 15% of 41 | 0.01 mg/L as N | 11.747 | 1964–1994 |
| Otter Tail County | 14% of 263 | 0.13 mg/L as N | 13 | 1964–2013 |
| Wadena County | 14% of 92 | 0.372 mg/L as N | 13 | 1964–2007 |
| Hubbard County | 13% of 115 | 0.994 mg/L as N | 11.001 | 1964–2017 |
| Kittson County | 13% of 47 | 0.59 mg/L as N | 10.391 | 1932–1995 |
| Lincoln County | 13% of 32 | 0.994 mg/L as N | 9.6 | 1966–1998 |
| Morrison County | 12% of 85 | 0.9 mg/L as N | 10.098 | 1966–2013 |
| Murray County | 12% of 34 | 0.55 mg/L as N | 10 | 1958–2007 |
| Norman County | 12% of 17 | 0.068 mg/L as N | 1.27 | 1964–1995 |
| Dodge County | 11% of 18 | 0.015 mg/L as N | 6.9 | 1971–2017 |
| Polk County | 11% of 82 | 0.102 mg/L as N | 6.67 | 1964–2015 |
| Benton County | 11% of 114 | 0.054 mg/L as N | 9.3 | 1969–2011 |
| Dakota County | 10% of 207 | 0.26 mg/L as N | 10 | 1960–2018 |
| Douglas County | 10% of 80 | 0.006 mg/L as N | 10 | 1964–2007 |
| Nobles County | 10% of 62 | 0.23 mg/L as N | 1.74 | 1955–2007 |
| Fillmore County | 9% of 107 | 1.5 mg/L as N | 9.5 | 1963–2006 |
| Cottonwood County | 9% of 46 | 0.104 mg/L as N | 5.71 | 1972–2013 |
| Marshall County | 9% of 58 | 0.361 mg/L as N | 8.4 | 1953–1995 |
| Pope County | 8% of 167 | 0.003 mg/L as N | 9.2 | 1964–2006 |
| Blue Earth County | 8% of 222 | 0.027 mg/L as N | 6.9 | 1974–2014 |
| Roseau County | 7% of 55 | 0.09 mg/L as N | 2.6 | 1954–1995 |
| Redwood County | 7% of 101 | 0.42 mg/L as N | 7.5 | 1953–2012 |
| Becker County | 7% of 88 | 0.011 mg/L as N | 5.4 | 1964–2007 |
| Pennington County | 7% of 15 | 0 mg/L as N | 2.3 | 1964–1995 |
| Todd County | 6% of 150 | 0.022 mg/L as N | 4 | 1964–2008 |
| Meeker County | 6% of 17 | 0 mg/L as N | 0.14 | 1955–2016 |
| Yellow Medicine County | 6% of 70 | 0.035 mg/L as N | 3.2 | 1964–2011 |
| Aitkin County | 6% of 35 | 0 mg/L as N | 0.7 | 1965–2013 |
| Crow Wing County | 6% of 179 | 0.003 mg/L as N | 3.5 | 1965–2013 |
| Lake of the Woods County | 6% of 18 | 0.05 mg/L as N | 0.59 | 1968–1972 |
| Goodhue County | 5% of 174 | 0.085 mg/L as N | 6.71 | 1963–2018 |
| Chippewa County | 5% of 22 | 0.008 mg/L as N | 1.2 | 1965–1998 |
| Renville County | 4% of 135 | 0.011 mg/L as N | 1.943 | 1964–2017 |
| Kanabec County | 4% of 23 | 0.03 mg/L as N | 4 | 1968–1995 |
| Winona County | 4% of 23 | 0.1 mg/L as N | 2.5 | 1963–2013 |
| Olmsted County | 4% of 101 | 0.994 mg/L as N | 7.003 | 1954–2014 |
| Faribault County | 4% of 26 | 0.04 mg/L as N | 0.61 | 1960–2014 |
| Traverse County | 4% of 28 | 0.049 mg/L as N | 2.3 | 1963–2013 |
| Lyon County | 3% of 58 | 0.023 mg/L as N | 1.65 | 1955–2006 |
| Lac qui Parle County | 3% of 29 | 0.005 mg/L as N | 0.181 | 1963–1998 |
| Grant County | 3% of 30 | 0.005 mg/L as N | 1.017 | 1964–2007 |
| Big Stone County | 3% of 31 | 0.115 mg/L as N | 3.84 | 1963–2007 |
| Watonwan County | 3% of 32 | 0.045 mg/L as N | 1.446 | 1964–2009 |
| Wabasha County | 3% of 109 | 0.442 mg/L as N | 5.422 | 1960–2007 |
| Nicollet County | 3% of 115 | 0 mg/L as N | 0.333 | 1968–2013 |
| Jackson County | 2% of 41 | 0.1 mg/L as N | 0.994 | 1969–2000 |
| Stevens County | 2% of 45 | 0.011 mg/L as N | 5 | 1964–2007 |
| Mille Lacs County | 2% of 47 | 0 mg/L as N | 0.994 | 1965–2006 |
| Swift County | 2% of 58 | 0.01 mg/L as N | 1.22 | 1963–2006 |
| Scott County | 2% of 59 | 0.07 mg/L as N | 5.33 | 1960–2018 |
| Hennepin County | 2% of 303 | 0 mg/L as N | 2.46 | 1960–2016 |
| Clay County | 2% of 125 | 0.007 mg/L as N | 0.271 | 1965–2015 |
| Anoka County | 1% of 305 | 0 mg/L as N | 3.5 | 1960–2016 |
| St. Louis County | 1% of 165 | 0.01 mg/L as N | 0.82 | 1956–2009 |
| Washington County | 1% of 190 | 1 mg/L as N | 4.2 | 1961–2018 |
| Itasca County | 1% of 98 | 0 mg/L as N | 0.35 | 1956–2012 |
| Chisago County | 1% of 105 | 0.007 mg/L as N | 4 | 1967–2011 |
| Sibley County | 1% of 106 | 0 mg/L as N | 0.054 | 1964–2014 |
| Mower County | 1% of 113 | 0 mg/L as N | 2.62 | 1960–2017 |
| Pine County | 1% of 137 | 0.012 mg/L as N | 1.333 | 1961–2014 |
| Carlton County | 0% of 157 | 0.012 mg/L as N | 0.574 | 1965–2016 |
| Wright County | 0% of 128 | 0.002 mg/L as N | 0.994 | 1961–2018 |
| Rice County | 0% of 96 | 0 mg/L as N | 0.25 | 1963–2018 |
| Carver County | 0% of 90 | 0.008 mg/L as N | 0.05 | 1961–2013 |
| Ramsey County | 0% of 87 | 0 mg/L as N | 2 | 1960–2007 |
| McLeod County | 0% of 86 | 0.005 mg/L as N | 0.021 | 1971–2011 |
| Beltrami County | 0% of 81 | 0 mg/L as N | 2.711 | 1965–2011 |
| Cass County | 0% of 61 | 0 mg/L as N | 2.9 | 1965–2011 |
| Houston County | 0% of 58 | 0.054 mg/L as N | 3.705 | 1963–2015 |
| Lake County | 0% of 47 | 0.31 mg/L as N | 3.41 | 1972–2017 |
| Wilkin County | 0% of 38 | 0.055 mg/L as N | 1.2 | 1964–1995 |
| Koochiching County | 0% of 31 | 0.01 mg/L as N | 1.9 | 1961–1995 |
| Clearwater County | 0% of 27 | 0 mg/L as N | 1.401 | 1966–2011 |
| Freeborn County | 0% of 24 | 0.02 mg/L as N | 0.49 | 1966–2007 |
| Cook County | 0% of 23 | 0 mg/L as N | 0 | 1995–2004 |
| Steele County | 0% of 22 | 0 mg/L as N | 0.06 | 1969–2007 |
| Le Sueur County | 0% of 19 | 0.03 mg/L as N | 0.994 | 1960–2005 |
| Mahnomen County | 0% of 19 | 0 mg/L as N | 0.587 | 1964–1995 |
| Martin County | 0% of 16 | 0.04 mg/L as N | 0.26 | 1964–2009 |
| Brown County | 0% of 12 | 0.04 mg/L as N | 0.2 | 1968–2009 |
| Waseca County | 0% of 12 | 0.055 mg/L as N | 0.18 | 1963–1993 |
| Red Lake County | 0% of 11 | 0.055 mg/L as N | 4.721 | 1966–2014 |
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Download this table (CSV) · public-domain source data: Water Quality Portal (USGS, EPA, NWQMC). How we calculate these numbers.
How Minnesota compares
Share of sampled wells above the EPA nitrate limit in each state we cover (states with 100+ wells).
| # | State | Above 10 mg/L (as nitrogen) |
|---|---|---|
| 1 | California | 10% of 16,344 |
| 2 | Pennsylvania | 8% of 6,478 |
| 3 | Minnesota | 6% of 7,259 |
| 4 | North Carolina | 5% of 1,964 |
| 5 | New York | 5% of 6,236 |
| 6 | Massachusetts | 4% of 2,556 |
| 7 | New Jersey | 4% of 3,915 |
| 8 | Wisconsin | 4% of 3,666 |
| 9 | Virginia | 3% of 1,394 |
| 10 | Maine | 2% of 726 |
| 11 | Michigan | 2% of 1,970 |
| 12 | Ohio | 1% of 1,239 |
| 13 | New Hampshire | 0% of 1,685 |
Where to test: official lab list for Minnesota
About this data
- Each well counts once, using its latest nitrate result in the Water Quality Portal (siteType = Well), downloaded 2026-10-18.
- Results reported as "not detected" count as below the limit. Results far outside the plausible range are withheld for review, not shown.
- Sampled wells include monitoring and research wells, not only household wells, and are not a random sample, so the share is a guide to local risk, not a rate for all homes.
- The limit is the EPA maximum contaminant level for public water systems (EPA).
Questions
Is nitrate common in Minnesota well water?
In our data, 434 of 7,259 sampled wells in Minnesota (6%) had a latest nitrate result above the EPA limit of 10 mg/L (as nitrogen), across 87 counties. That ranks Minnesota 3 of 13 states we cover for this share.
Which Minnesota counties have the most wells above the nitrate limit?
Among counties with at least 10 sampled wells: Isanti County (30%, 15 of 50 wells); Pipestone County (22%, 4 of 18 wells); Stearns County (20%, 64 of 327 wells).
Does this tell me whether my well is safe?
No. These are past results from wells sampled by USGS, EPA and state programs, including monitoring wells, and levels differ from well to well. The only way to know your water is to test your own well at a certified lab.
How do I test my well for nitrate in Minnesota?
Order a nitrate test from a lab on Minnesota's official certified-lab list (linked on this page) and ask for its bottles and sampling instructions. Our test helper suggests what else to test for at the same time.
What should I do if my nitrate result is above 10 mg/L (as nitrogen)?
Retest to confirm, use another water source for drinking and cooking while you sort it out, and look at certified treatment options. Our guide walks through each step with sources.