Data & Methodology — Fillmore County

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

Contaminant Data — All Analytes

339 well testing events on record, covering 18 analytes. Data spans 1961 to 2024.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. MN Avg
PFOA municipal 13 2007–2023 46%
388% of limit ~ typical
Iron 116 1963–2024 91%
63% of limit ↓ 91% below
PFOS municipal 6 2023 33%
350% of limit ↑ 74% above
Nitrate 140 1963–2025 97%
47% of limit ↑ 93% above
Arsenic 24 1977–2024 62%
7% of limit ↓ 92% below
Lead 24 1977–2024 42%
16% of limit ↓ 65% below
Manganese 106 1963–2024 89%
22% of limit ↓ 96% below
Chloride 324 1963–2025 99%
5% of limit ↓ 36% below
Fluoride 112 1963–2025 53%
5% of limit ↓ 28% below
HFPO-DA (GenX) municipal 4 2023 0%
— —
Nitrite 119 1992–2025 43%
0% of limit ↓ 75% below
PFHxS municipal 6 2023 33%
65% of limit ~ typical
PFNA municipal 7 2007–2023 0%
— —
Sulfate 169 1963–2025 100%
7% of limit ↓ 62% below
Sodium 113 1963–2024 100%
— ↓ 91% below
pH 22 1963–2021 100%
— ~ typical
PFBS municipal 4 2023 0%
— —
Hardness 21 1963–1981 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 Fillmore County

Of the 24 arsenic tests on record for Fillmore County (1977–2024), 38% found none, and half were below 0.25 µg/L.

Of the 324 chloride tests on record for Fillmore County (1963–2025), 1% found none, and half were below 12.3 mg/L.

Of the 112 fluoride tests on record for Fillmore County (1963–2025), 47% found none, and half were below 100 µg/L.

Of the 116 iron tests on record for Fillmore County (1963–2024), 9% found none, and half were below 120 µg/L.

Of the 24 lead tests on record for Fillmore County (1977–2024), 58% found none.

Of the 106 manganese tests on record for Fillmore County (1963–2024), 11% found none, and half were below 9.3 µg/L.

Of the 140 nitrate tests on record for Fillmore County (1963–2025), 3% found none, and half were below 4.6 mg/L.

Of the 169 sulfate tests on record for Fillmore County (1963–2025), 0% found none, and half were below 18.2 mg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 116 samples
  • Nitrate 140 samples
  • Arsenic 24 samples
  • Lead 24 samples
  • Manganese 106 samples
  • Chloride 324 samples
  • Fluoride 112 samples
  • Nitrite 119 samples
  • Sulfate 169 samples
  • Sodium 113 samples
  • pH 22 samples
  • Hardness 21 samples

Limited data (<15 samples) — interpret with caution

  • PFOA 13 samples
  • PFOS 6 samples
  • PFHxS 6 samples
  • PFNA 7 samples

Public vs. Private Water in Fillmore County

58 Active public water systems
17,313 Residents on public water
43% Households on private wells

Public water systems in Fillmore 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 Fillmore 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 Fillmore County Prevalence MN Average Source Year
Arsenic Cancer prevalence 6.1% 7.0% 2020
Arsenic Kidney disease rate 3.3% 2.9% 2020
Lead Heart disease rate 8.0% 6.6% 2020

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