Data & Methodology — Genesee County

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

Contaminant Data — All Analytes

109 well testing events on record, covering 19 analytes. Data spans 1953 to 2023.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. MI Avg
Iron 54 1953–1997 98%
133% of limit ↓ 33% below
Arsenic 26 1975–1997 92%
115% of limit ↑ 259% above
Chloride 61 1953–1997 100%
26% of limit ↑ 109% above
Manganese 49 1953–1997 98%
39% of limit ↓ 72% below
Sulfate 59 1953–1997 98%
10% of limit ↓ 37% below
Fluoride 43 1953–1997 100%
22% of limit ↑ 183% above
HFPO-DA (GenX) municipal 58 2023–2025 0%
— —
Lead 3 1975–1984 0%
— —
Nitrate 29 1953–1997 66%
0% of limit ↓ 95% below
Nitrite 10 1975–1997 10%
1% of limit ↑ 129% above
PFHxS municipal 58 2023–2025 0%
— —
PFNA municipal 58 2023–2025 0%
— —
PFOA municipal 58 2023–2025 0%
— —
PFOS municipal 58 2023–2025 0%
— —
Uranium 6 1976–1988 83%
1% of limit ↑ 47% above
Sodium 54 1953–1997 100%
— ↑ 351% above
pH 57 1953–1997 100%
— ~ typical
PFBS municipal 58 2023–2025 0%
— —
Hardness 61 1953–1997 100%
— ↑ 97% 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 MI.

Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 54 samples
  • Arsenic 26 samples
  • Chloride 61 samples
  • Manganese 49 samples
  • Sulfate 59 samples
  • Fluoride 43 samples
  • Nitrate 29 samples
  • Sodium 54 samples
  • pH 57 samples
  • Hardness 61 samples

Limited data (<15 samples) — interpret with caution

  • Lead 3 samples
  • Nitrite 10 samples
  • Uranium 6 samples

No private-well PFAS data for Genesee County

We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Genesee County. PFAS testing for private wells requires a dedicated lab panel (~$300–$500). If you are near a military base, airport, or industrial site, consider testing proactively. Learn more about PFAS →

Public vs. Private Water in Genesee County

396 Active public water systems
335,173 Residents on public water
17% Households on private wells

Public water systems in Genesee 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 Genesee 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 Genesee County Prevalence MI Average Source Year
Arsenic Kidney disease rate 3.6% 3.2% 2020
Arsenic Cancer prevalence 9.1% 7.2% 2023
Arsenic Cancer prevalence 7.3% 7.2% 2020

Source: CDC PLACES county-level estimates. Raw data: Download Genesee 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: 2026-07-15

Full methodology →