Data & Methodology — Grand Traverse County

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

Contaminant Data — All Analytes

232 well testing events on record, covering 20 analytes. Data spans 1967 to 2023.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. MI Avg
Iron 39 1976–1987 95%
47% of limit ↓ 87% below
Lead 39 1976–1987 18%
667% of limit ↑ 3183% above
Manganese 39 1976–1987 87%
40% of limit ↓ 55% below
Arsenic 38 1977–1987 16%
15% of limit ↓ 50% below
Nitrate 219 1977–1987 57%
11% of limit ↑ 266% above
Chloride 218 1977–1987 100%
1% of limit ↓ 94% below
Fluoride 38 1977–1987 39%
5% of limit ↓ 40% below
HFPO-DA (GenX) municipal 14 2023–2025 0%
— —
Nitrite 219 1977–1987 15%
1% of limit ~ typical
PFHxS municipal 14 2023–2025 0%
— —
PFNA municipal 15 2010–2025 0%
— —
PFOA municipal 15 2010–2025 0%
— —
PFOS municipal 14 2023–2025 0%
— —
Radon 1 1991 100%
2% of limit ↓ 65% below
Sulfate 38 1977–1987 100%
5% of limit ↓ 76% below
Uranium 4 1976–1987 100%
0% of limit ↓ 47% below
Sodium 38 1977–1987 100%
— ↓ 93% below
pH 219 1976–1987 100%
— ~ typical
PFBS municipal 14 2023–2025 14%
— ~ typical
Hardness 38 1977–1987 100%
— ↓ 34% 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 Grand Traverse County

Of the 38 arsenic tests on record for Grand Traverse County (1977–1987), 84% found none.

Of the 218 chloride tests on record for Grand Traverse County (1977–1987), 0% found none, and half were below 3.05 mg/L.

Of the 38 fluoride tests on record for Grand Traverse County (1977–1987), 61% found none.

Of the 39 iron tests on record for Grand Traverse County (1976–1987), 5% found none, and half were below 130 µg/L.

Of the 39 lead tests on record for Grand Traverse County (1976–1987), 82% found none.

Of the 39 manganese tests on record for Grand Traverse County (1976–1987), 13% found none, and half were below 20 µg/L.

Of the 219 nitrate tests on record for Grand Traverse County (1977–1987), 43% found none, and half were below 300 µg/L.

Of the 38 sulfate tests on record for Grand Traverse County (1977–1987), 0% found none, and half were below 12.5 mg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Iron 39 samples
  • Lead 39 samples
  • Manganese 39 samples
  • Arsenic 38 samples
  • Nitrate 219 samples
  • Chloride 218 samples
  • Fluoride 38 samples
  • Nitrite 219 samples
  • PFNA 15 samples
  • PFOA 15 samples
  • Sulfate 38 samples
  • Sodium 38 samples
  • pH 219 samples
  • Hardness 38 samples

Limited data (<15 samples) — interpret with caution

  • Radon 1 sample
  • Uranium 4 samples

Public vs. Private Water in Grand Traverse County

180 Active public water systems
57,994 Residents on public water
55% Households on private wells

Public water systems in Grand Traverse 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 Grand Traverse 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 Grand Traverse County Prevalence MI Average Source Year
Lead Heart disease rate 7.2% 7.4% 2020
Arsenic Cancer prevalence 8.0% 7.2% 2023
Lead Heart disease rate 5.1% 7.4% 2023
Arsenic Cancer prevalence 8.1% 7.2% 2020
Arsenic Kidney disease rate 3.1% 3.2% 2020

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