Roseau County, Minnesota

Arsenic: 6 of 15 sampled wells (40%) above the EPA limit of 10 µg/L. Nitrate: 4 of 55 sampled wells (7%) above the EPA limit of 10 mg/L as N. Samples 1954-04-08 to 1995-08-09; updated 2026-10-18. Source: Water Quality Portal (USGS, EPA, NWQMC), siteType=Well.

What wells in this county have measured for arsenic and nitrate. A local picture only: test your own well to know your water.

Arsenic

6 of 15 sampled wells (40%) had a latest result above the EPA limit of 10 µg/L.

Median (latest per well): 3.21 µg/L
90th percentile: 18.5 µg/L
Highest: 24.9 µg/L
Non-detects: 3 wells' latest result was "not detected" with no detection limit reported; they are counted as below the limit.
Samples: 15, 1995-08-08 to 1995-08-09
Source: Water Quality Portal (USGS, EPA, NWQMC), siteType=Well, downloaded 2026-10-18

Nitrate

4 of 55 sampled wells (7%) had a latest result above the EPA limit of 10 mg/L as N.

Median (latest per well): 0.09 mg/L as N
90th percentile: 2.6 mg/L as N
Highest: 22 mg/L as N
Non-detects: 12 wells' latest result was "not detected" with no detection limit reported; they are counted as below the limit.
Samples: 55, 1954-04-08 to 1995-08-09
Source: Water Quality Portal (USGS, EPA, NWQMC), siteType=Well, downloaded 2026-10-18

Includes monitoring, research and private wells reported to the Water Quality Portal. Non-detects count only when the lab's detection limit is at or below the EPA limit. Method: data rules.

What to do next

Test your own well. County numbers cannot tell you what is in your water. See which tests fit your well.
Use a lab certified by Minnesota. Certified labs in Minnesota.
Compare your results with the EPA limits (arsenic 10 µg/L, nitrate 10 mg/L as N). If a result is above a limit, contact your county or state health department.
If a result is high: arsenic guide · nitrate guide · bacteria guide · salesperson checklist.
Test again every year for bacteria and nitrate. Get a yearly reminder.