Data & Methodology — Sibley County

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

Contaminant Data — All Analytes

131 well testing events on record, covering 20 analytes. Data spans 1964 to 2019.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. MN Avg
Iron 124 1964–2014 99%
699% of limit ~ typical
Manganese 24 1964–2014 100%
117% of limit ↓ 76% below
Arsenic 108 1993–2014 91%
86% of limit ~ typical
PFOS municipal 3 2025 33%
300% of limit ↑ 49% above
PFHxS municipal 3 2025 33%
260% of limit ↑ 225% above
PFOA municipal 3 2025 33%
2325% of limit ↑ 441% above
Sulfate 124 1964–2014 99%
38% of limit ↑ 99% above
Lead 108 1993–2014 85%
1% of limit ↓ 98% below
Nitrate 123 1964–2014 36%
0% of limit ↓ 99% below
Chloride 124 1964–2014 100%
1% of limit ↓ 93% below
Fluoride 124 1964–2014 99%
6% of limit ~ typical
HFPO-DA (GenX) municipal 2 2025 0%
— —
Nitrite 104 1989–2014 5%
0% of limit ↓ 67% below
PFNA municipal 2 2025 0%
— —
Radon 3 2013–2014 100%
86% of limit ↑ 65% above
Uranium 90 1980–2014 92%
2% of limit ↓ 52% below
Hardness 9 1964–2014 100%
— ↑ 38% above
PFBS municipal 3 2025 33%
— ↑ 87% above
pH 13 1964–2014 100%
— ~ typical
Sodium 124 1964–2014 100%
— ↑ 100% above

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 Sibley County

Of the 108 arsenic tests on record for Sibley County (1993–2014), 9% found none, and half were below 7.3 µg/L.

Of the 124 chloride tests on record for Sibley County (1964–2014), 0% found none, and half were below 1.34 mg/L.

Of the 124 fluoride tests on record for Sibley County (1964–2014), 1% found none, and half were below 230 µg/L.

Of the 124 iron tests on record for Sibley County (1964–2014), 1% found none, and half were below 2.08 mg/L.

Of the 108 lead tests on record for Sibley County (1993–2014), 15% found none, and half were below 0.111 µg/L.

Of the 24 manganese tests on record for Sibley County (1964–2014), 0% found none, and half were below 58.5 µg/L.

Of the 123 nitrate tests on record for Sibley County (1964–2014), 64% found none.

Of the 124 sulfate tests on record for Sibley County (1964–2014), 1% found none, and half were below 93.8 mg/L.

Of the 90 uranium tests on record for Sibley County (1980–2014), 8% found none, and half were below 0.487 µg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 124 samples
  • Manganese 24 samples
  • Arsenic 108 samples
  • Sulfate 124 samples
  • Lead 108 samples
  • Nitrate 123 samples
  • Chloride 124 samples
  • Fluoride 124 samples
  • Nitrite 104 samples
  • Uranium 90 samples
  • Sodium 124 samples

Limited data (<15 samples) — interpret with caution

  • PFOS 3 samples
  • PFHxS 3 samples
  • PFOA 3 samples
  • Radon 3 samples
  • Hardness 9 samples
  • PFBS 3 samples
  • pH 13 samples

Public vs. Private Water in Sibley County

20 Active public water systems
9,745 Residents on public water
39% Households on private wells

Public water systems in Sibley 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 Sibley 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 Sibley County Prevalence MN Average Source Year
Arsenic Cancer prevalence 6.0% 7.0% 2020
Arsenic Kidney disease rate 2.5% 2.9% 2020
Lead Heart disease rate 5.5% 6.6% 2020

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