Data & Sources — Jefferson County

How we built the Jefferson County well water report: sample counts, data sources, and confidence tiers.

Sample Summary

36638 total samples analyzed for Jefferson County. Data spans 1929 to 2022.

Confidence Tiers

Data Sources

This report aggregates data from the following public databases:

Methodology

Raw records are normalized to µg/L, deduplicated by sample ID, and filtered to remove certified outliers. Analyte names are mapped to EPA canonical forms. See the full methodology page for details.

Last updated: 2026-05-08