Data & Methodology — Bay County

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

Contaminant Data — All Analytes

79 well testing events on record, covering 19 analytes. Data spans 1967 to 2024.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. MI Avg
Chloride 44 1975–1992 98%
352% of limit ↑ 1761% above
Iron 32 1975–1988 100%
207% of limit ↓ 42% below
Sulfate 30 1975–1988 100%
120% of limit ↑ 469% above
Manganese 32 1975–1988 100%
107% of limit ↑ 21% above
Lead 26 1975–1984 23%
2000% of limit ↑ 9748% above
Arsenic 31 1975–1988 81%
20% of limit ↓ 33% below
Fluoride 31 1975–1988 90%
10% of limit ~ typical
HFPO-DA (GenX) municipal 31 2023–2025 0%
— —
Nitrate 23 1975–1984 22%
0% of limit ↓ 100% below
Nitrite 23 1975–1984 35%
7% of limit ↑ 490% above
PFHxS municipal 31 2023–2025 0%
— —
PFNA municipal 31 2023–2025 0%
— —
PFOA municipal 33 2010–2025 0%
— —
PFOS municipal 31 2023–2025 0%
— —
Uranium 22 1978–1984 23%
2% of limit ↑ 91% above
Hardness 31 1975–1988 100%
— ↑ 125% above
Sodium 31 1975–1988 100%
— ↑ 3085% above
pH 37 1975–1991 100%
— ~ typical
PFBS municipal 31 2023–2025 0%
— —

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 Bay County

Of the 31 arsenic tests on record for Bay County (1975–1988), 19% found none, and half were below 2 µg/L.

Of the 44 chloride tests on record for Bay County (1975–1992), 2% found none, and half were below 825 mg/L.

Of the 31 fluoride tests on record for Bay County (1975–1988), 10% found none, and half were below 300 µg/L.

Of the 32 iron tests on record for Bay County (1975–1988), 0% found none, and half were below 620 µg/L.

Of the 26 lead tests on record for Bay County (1975–1984), 77% found none.

Of the 32 manganese tests on record for Bay County (1975–1988), 0% found none, and half were below 53.5 µg/L.

Of the 23 nitrate tests on record for Bay County (1975–1984), 78% found none.

Of the 30 sulfate tests on record for Bay County (1975–1988), 0% found none, and half were below 300 mg/L.

Of the 22 uranium tests on record for Bay County (1978–1984), 77% found none.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Chloride 44 samples
  • Iron 32 samples
  • Sulfate 30 samples
  • Manganese 32 samples
  • Lead 26 samples
  • Arsenic 31 samples
  • Fluoride 31 samples
  • Nitrate 23 samples
  • Nitrite 23 samples
  • PFOA 33 samples
  • Uranium 22 samples
  • Hardness 31 samples
  • Sodium 31 samples
  • pH 37 samples

Public vs. Private Water in Bay County

29 Active public water systems
99,076 Residents on public water
5% Households on private wells

Public water systems in Bay 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 Bay 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 Bay County Prevalence MI Average Source Year
Lead Heart disease rate 5.8% 7.4% 2023
Lead Heart disease rate 6.3% 7.4% 2020
Arsenic Cancer prevalence 8.1% 7.2% 2020
Arsenic Kidney disease rate 3.5% 3.2% 2020

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