Data & Methodology — Oconto County

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

Contaminant Data — All Analytes

50 well testing events on record, covering 20 analytes. Data spans 1935 to 2020.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. WI Avg
Iron 45 1935–2014 93%
60% of limit ↓ 75% below
Arsenic 13 1976–2014 92%
12% of limit ↓ 26% below
Chloride 45 1935–2014 100%
2% of limit ↓ 53% below
Fluoride 42 1946–2014 90%
5% of limit ~ typical
HFPO-DA (GenX) municipal 12 2022–2025 0%
— —
Lead 13 1976–2014 46%
0% of limit ↓ 50% below
Manganese 45 1935–2014 91%
49% of limit ↓ 63% below
Nitrate 32 1935–2014 44%
2% of limit ↓ 91% below
Nitrite 28 1935–2014 64%
0% of limit ↓ 69% below
PFHxS municipal 12 2022–2025 25%
4% of limit ↓ 68% below
PFNA municipal 12 2022–2025 33%
5% of limit ↑ 44% above
PFOA municipal 12 2022–2025 75%
15% of limit ~ typical
PFOS municipal 12 2022–2025 42%
11% of limit ↓ 82% below
Radon 4 1995–2003 100%
8% of limit ↓ 51% below
Sulfate 45 1935–2014 100%
8% of limit ~ typical
Uranium 10 2002–2014 100%
2% of limit ~ typical
Hardness 45 1935–2014 100%
— ↓ 21% below
PFBS municipal 12 2022–2025 42%
— ↓ 67% below
pH 39 1946–2014 100%
— ~ typical
Sodium 28 1964–2014 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 WI.

Compare your result with Oconto County

Of the 45 chloride tests on record for Oconto County (1935–2014), 0% found none, and half were below 5.3 mg/L.

Of the 42 fluoride tests on record for Oconto County (1946–2014), 10% found none, and half were below 200 µg/L.

Of the 45 iron tests on record for Oconto County (1935–2014), 7% found none, and half were below 100 µg/L.

Of the 45 manganese tests on record for Oconto County (1935–2014), 9% found none, and half were below 20 µg/L.

Of the 32 nitrate tests on record for Oconto County (1935–2014), 56% found none.

Of the 45 sulfate tests on record for Oconto County (1935–2014), 0% found none, and half were below 20 mg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 45 samples
  • Chloride 45 samples
  • Fluoride 42 samples
  • Manganese 45 samples
  • Nitrate 32 samples
  • Nitrite 28 samples
  • Sulfate 45 samples
  • Hardness 45 samples
  • pH 39 samples
  • Sodium 28 samples

Limited data (<15 samples) — interpret with caution

  • Arsenic 13 samples
  • HFPO-DA (GenX) 12 samples
  • Lead 13 samples
  • PFHxS 12 samples
  • PFNA 12 samples
  • PFOA 12 samples
  • PFOS 12 samples
  • Radon 4 samples
  • Uranium 10 samples
  • PFBS 12 samples

CDC Health Outcome Correlations

Where contaminants detected in Oconto 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 Oconto County Prevalence WI Average Source Year
Lead Heart disease rate 5.5% 6.5% 2020
Radon Cancer prevalence 6.0% 7.0% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Oconto 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 WI with at least one sample for that analyte.

Last updated: 2026-07-15

Full methodology →