Data & Methodology — Nicollet County

Full contaminant data, sample history, and sourcing for Nicollet County. For readers who want to go beyond the summary.

Contaminant Data — All Analytes

165 well testing events on record, covering 21 analytes. Data spans 1958 to 2024.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. MN Avg
Radon 1 2014 100%
103% of limit ↑ 99% above
Iron 136 1968–2014 97%
610% of limit ~ typical
Manganese 33 1968–2014 100%
224% of limit ↓ 54% below
Sulfate 150 1968–2023 100%
54% of limit ↑ 183% above
PFOS municipal 7 2023–2025 29%
1150% of limit ↑ 472% above
PFOA municipal 7 2023–2025 29%
755% of limit ↑ 76% above
Arsenic 116 1993–2014 84%
43% of limit ↓ 50% below
Lead 116 1993–2014 83%
1% of limit ↓ 98% below
Nitrate 137 1968–2013 41%
0% of limit ↓ 98% below
Uranium 89 2012–2014 94%
4% of limit ~ typical
Chloride 150 1968–2023 100%
1% of limit ↓ 84% below
Fluoride 150 1968–2023 93%
5% of limit ↓ 34% below
HFPO-DA (GenX) municipal 5 2023–2025 0%
— —
Nitrite 109 1989–2013 4%
0% of limit ↓ 65% below
PFHxS municipal 5 2023–2025 0%
— —
PFNA municipal 5 2023–2025 0%
— —
Sodium 149 1968–2023 100%
— ↑ 53% above
pH 23 1968–2014 100%
— ~ typical
PFBS municipal 5 2023–2025 0%
— —
Hardness 12 1968–2014 100%
— ↑ 37% above
E. coli 1 2020 100%
— ~ typical

Distribution shows the share of samples in each concentration band relative to the EPA Maximum Contaminant Level (MCL): Low = below half the MCL, Moderate = between half and the MCL, High = above the MCL. Analytes without an MCL (e.g. sodium, pH) show — in the limit columns. State average is based on county median values across MN.

Compare your result with Nicollet County

Of the 116 arsenic tests on record for Nicollet County (1993–2014), 16% found none, and half were below 3.05 µg/L.

Of the 150 chloride tests on record for Nicollet County (1968–2023), 0% found none, and half were below 3 mg/L.

Of the 150 fluoride tests on record for Nicollet County (1968–2023), 7% found none, and half were below 172 µg/L.

Of the 136 iron tests on record for Nicollet County (1968–2014), 3% found none, and half were below 1.79 mg/L.

Of the 116 lead tests on record for Nicollet County (1993–2014), 17% found none, and half were below 0.11 µg/L.

Of the 33 manganese tests on record for Nicollet County (1968–2014), 0% found none, and half were below 112 µg/L.

Of the 137 nitrate tests on record for Nicollet County (1968–2013), 59% found none.

Of the 150 sulfate tests on record for Nicollet County (1968–2023), 0% found none, and half were below 134 mg/L.

Of the 89 uranium tests on record for Nicollet County (2012–2014), 6% found none, and half were below 1.17 µg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 136 samples
  • Manganese 33 samples
  • Sulfate 150 samples
  • Arsenic 116 samples
  • Lead 116 samples
  • Nitrate 137 samples
  • Uranium 89 samples
  • Chloride 150 samples
  • Fluoride 150 samples
  • Nitrite 109 samples
  • Sodium 149 samples
  • pH 23 samples

Limited data (<15 samples) — interpret with caution

  • Radon 1 sample
  • PFOS 7 samples
  • PFOA 7 samples
  • Hardness 12 samples
  • E. coli 1 sample

Public vs. Private Water in Nicollet County

26 Active public water systems
30,952 Residents on public water
18% Households on private wells

Public water systems in Nicollet County are regulated by the EPA and must test and report contaminant levels. Private well owners are responsible for their own testing — there is no routine monitoring of private wells by any government agency.

CDC Health Outcome Correlations

Where contaminants detected in Nicollet County have established associations with specific health outcomes, we cross-reference CDC PLACES county-level prevalence data. This is a contextual signal, not a causal claim.

Contaminant Associated Condition Nicollet County Prevalence MN Average Source Year
Arsenic Cancer prevalence 6.8% 7.0% 2020
Arsenic Kidney disease rate 2.7% 2.9% 2020
Lead Heart disease rate 5.9% 6.6% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Nicollet County CDC PLACES data →

Data Sources

This report aggregates data from the following public databases:

Methodology

Raw records are downloaded from the Water Quality Portal and normalized to µg/L (ppb). Records are deduplicated by sample ID and date, and certified outliers are excluded. Analyte names are mapped to EPA canonical forms. Detection rates, distribution bands, and MCL comparisons are computed from the normalized dataset.

Distribution bands use the EPA Maximum Contaminant Level as the threshold: concentrations below 50% of the MCL are classed as Low, between 50% and 100% as Moderate, and above 100% as High. For analytes without an MCL (sodium, hardness, pH), distribution is not computed.

State comparison uses the median of county median values across all counties in MN with at least one sample for that analyte.

Last updated: 2026-08-04

Full methodology →