Data & Methodology — Essex County

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

Contaminant Data — All Analytes

4 well testing events on record, covering 14 analytes. Data spans 1957 to 2024.

Contaminant Samples Years Detection Rate Distribution LowModHigh vs. Limit vs. VT Avg
Manganese 53 1967–1995 100%
12% of limit ↓ 98% below
Iron 26 1967–1995 100%
17% of limit ↓ 92% below
Lead 239 — 100%
7% of limit ↓ 91% below
Chloride 124 1967–1995 100%
1% of limit ↓ 88% below
Arsenic 122 1995 0%
— —
Fluoride 138 1967–1995 99%
3% of limit ~ typical
Nitrate 172 1967–1995 100%
2% of limit ↓ 24% below
Nitrite 151 1995 99%
2% of limit ~ typical
Radon 2 1995 100%
11% of limit ↓ 98% below
Sulfate 3 1967–1995 100%
3% of limit ↓ 41% below
Uranium 95 1995 69%
3% of limit ↓ 59% below
Sodium 26 1967–1995 100%
— ↑ 84% above
pH 23 1967–1995 100%
— ~ typical
Hardness 27 1967–1995 100%
— ↓ 45% 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 VT.

Compare your result with Essex County

Of the 122 arsenic tests on record for Essex County (1995), 100% found none.

Of the 124 chloride tests on record for Essex County (1967–1995), 0% found none, and half were below 2.5 mg/L.

Of the 138 fluoride tests on record for Essex County (1967–1995), 1% found none, and half were below 125 µg/L.

Of the 26 iron tests on record for Essex County (1967–1995), 0% found none, and half were below 50 µg/L.

Of the 239 lead tests on record for Essex County, 0% found none, and half were below 1 µg/L.

Of the 53 manganese tests on record for Essex County (1967–1995), 0% found none, and half were below 6 µg/L.

Of the 172 nitrate tests on record for Essex County (1967–1995), 0% found none, and half were below 250 µg/L.

Of the 95 uranium tests on record for Essex County (1995), 31% found none, and half were below 1 µg/L.

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Data Coverage & Gaps

Well-sampled analytes (15+ samples)

  • Manganese 53 samples
  • Iron 26 samples
  • Lead 239 samples
  • Chloride 124 samples
  • Arsenic 122 samples
  • Fluoride 138 samples
  • Nitrate 172 samples
  • Nitrite 151 samples
  • Uranium 95 samples
  • Sodium 26 samples
  • pH 23 samples
  • Hardness 27 samples

Limited data (<15 samples) — interpret with caution

  • Radon 2 samples
  • Sulfate 3 samples

No private-well PFAS data for Essex County

We have no private well sampling data for PFAS compounds (PFOA, PFOS, PFNA, and related chemicals) in Essex 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 Essex County

18 Active public water systems
5,070 Residents on public water
49% Households on private wells

Public water systems in Essex 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 Essex 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 Essex County Prevalence VT Average Source Year
Lead Heart disease rate 6.1% 6.3% 2020

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

Last updated: 2026-07-31

Full methodology →