Data & Methodology — Alger County

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

Contaminant Data — All Analytes

57 well testing events on record, covering 16 analytes. Data spans 1960 to 2021.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. MI Avg
Radon 2 2014 100%
106% of limit ↑ 1410% above
Iron 28 1960–2014 93%
20% of limit ↓ 94% below
Manganese 27 1960–2014 96%
49% of limit ↓ 44% below
Arsenic 26 1974–2014 85%
10% of limit ↓ 67% below
Chloride 34 1960–2014 100%
0% of limit ↓ 97% below
Fluoride 28 1960–2014 89%
5% of limit ↓ 40% below
Lead 26 1974–2014 42%
0% of limit ↓ 100% below
Nitrate 30 1960–2014 90%
0% of limit ↓ 92% below
Nitrite 23 1977–2014 52%
0% of limit ↓ 100% below
PFNA 18 2018 0%
— —
PFOA 22 2010–2018 0%
— —
Sulfate 34 1960–2014 100%
4% of limit ↓ 82% below
Uranium 4 1980–2014 100%
2% of limit ↑ 106% above
Sodium 30 1960–2014 100%
— ↓ 94% below
pH 35 1960–2014 100%
— ~ typical
Hardness 34 1960–2014 100%
— ↓ 58% below

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 MI.

Compare your result with Alger County

Of the 26 arsenic tests on record for Alger County (1974–2014), 15% found none, and half were below 1 µg/L.

Of the 34 chloride tests on record for Alger County (1960–2014), 0% found none, and half were below 1.2 mg/L.

Of the 28 fluoride tests on record for Alger County (1960–2014), 11% found none, and half were below 100 µg/L.

Of the 28 iron tests on record for Alger County (1960–2014), 7% found none, and half were below 60 µg/L.

Of the 26 lead tests on record for Alger County (1974–2014), 58% found none.

Of the 27 manganese tests on record for Alger County (1960–2014), 4% found none, and half were below 20 µg/L.

Of the 30 nitrate tests on record for Alger County (1960–2014), 10% found none, and half were below 15 µg/L.

Of the 22 pfoa tests on record for Alger County (2010–2018), 100% found none.

Of the 34 sulfate tests on record for Alger County (1960–2014), 0% found none, and half were below 9.7 mg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 28 samples
  • Manganese 27 samples
  • Arsenic 26 samples
  • Chloride 34 samples
  • Fluoride 28 samples
  • Lead 26 samples
  • Nitrate 30 samples
  • Nitrite 23 samples
  • PFNA 18 samples
  • PFOA 22 samples
  • Sulfate 34 samples
  • Sodium 30 samples
  • pH 35 samples
  • Hardness 34 samples

Limited data (<15 samples) — interpret with caution

  • Radon 2 samples
  • Uranium 4 samples

Public vs. Private Water in Alger County

87 Active public water systems
9,847 Residents on public water
53% Households on private wells

Public water systems in Alger 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 Alger 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 Alger County Prevalence MI Average Source Year
Radon Cancer prevalence 6.0% 7.2% 2020

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

Last updated: 2026-08-04

Full methodology →